[v6,1/7] slimbus: Device management on SLIMbus

From: Sagar Dharia <sdharia@codeaurora.org>

SLIMbus (Serial Low Power Interchip Media Bus) is a specification
developed by MIPI (Mobile Industry Processor Interface) alliance.
SLIMbus is a 2-wire implementation, which is used to communicate with
peripheral components like audio-codec.
SLIMbus uses Time-Division-Multiplexing to accommodate multiple data
channels, and control channel. Control channel has messages to do
device-enumeration, messages to send/receive control-data to/from
slimbus devices, messages for port/channel management, and messages to
do bandwidth allocation.
The framework supports multiple instances of the bus (1 controller per
bus), and multiple slave devices per controller.

This patch does device enumeration, logical address assignment,
informing device when the device reports present/absent etc.
Reporting present may need the driver to do the needful (e.g. turning
on voltage regulators powering the device). Additionally device is
probed when it reports present if that device doesn't need any such
steps mentioned above.

Signed-off-by: Sagar Dharia <sdharia@codeaurora.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
---
 Documentation/devicetree/bindings/slimbus/bus.txt |  57 ++
 Documentation/slimbus/summary                     | 109 ++++
 drivers/Kconfig                                   |   2 +
 drivers/Makefile                                  |   1 +
 drivers/slimbus/Kconfig                           |  11 +
 drivers/slimbus/Makefile                          |   5 +
 drivers/slimbus/slim-core.c                       | 695 ++++++++++++++++++++++
 include/linux/mod_devicetable.h                   |  13 +
 include/linux/slimbus.h                           | 299 ++++++++++
 9 files changed, 1192 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/slimbus/bus.txt
 create mode 100644 Documentation/slimbus/summary
 create mode 100644 drivers/slimbus/Kconfig
 create mode 100644 drivers/slimbus/Makefile
 create mode 100644 drivers/slimbus/slim-core.c
 create mode 100644 include/linux/slimbus.h

Hi, I have some more or less trivial comments below.

On Fri, Oct 06, 2017 at 05:51:30PM +0200, srinivas.kandagatla@linaro.org wrote:
> From: Sagar Dharia <sdharia@codeaurora.org>
> 
> SLIMbus (Serial Low Power Interchip Media Bus) is a specification
> developed by MIPI (Mobile Industry Processor Interface) alliance.
> SLIMbus is a 2-wire implementation, which is used to communicate with
> peripheral components like audio-codec.
> SLIMbus uses Time-Division-Multiplexing to accommodate multiple data
> channels, and control channel. Control channel has messages to do
> device-enumeration, messages to send/receive control-data to/from
> slimbus devices, messages for port/channel management, and messages to
> do bandwidth allocation.
> The framework supports multiple instances of the bus (1 controller per
> bus), and multiple slave devices per controller.
> 
> This patch does device enumeration, logical address assignment,
> informing device when the device reports present/absent etc.
> Reporting present may need the driver to do the needful (e.g. turning
> on voltage regulators powering the device). Additionally device is
> probed when it reports present if that device doesn't need any such
> steps mentioned above.
> 
> Signed-off-by: Sagar Dharia <sdharia@codeaurora.org>
> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
> ---
[...]
> +SLIMbus example for Qualcomm's slimbus manager component:
> +
> +	slim@28080000 {
> +		compatible = "qcom,slim-msm";
> +		reg = <0x28080000 0x2000>,
> +		interrupts = <0 33 0>;
> +		clocks = <&lcc SLIMBUS_SRC>, <&lcc AUDIO_SLIMBUS_CLK>;
> +		clock-names = "iface_clk", "core_clk";
> +		#address-cells = <2>;
> +		#size-cells = <0>;
> +
> +		codec: wcd9310@1{
> +			compatible = "slim217,60"";
			                        ^ spurious quote?

> +			reg = <1 0>;
> +		};
> +	};
> diff --git a/Documentation/slimbus/summary b/Documentation/slimbus/summary
> new file mode 100644
> index 0000000..e7f90bb
> --- /dev/null
> +++ b/Documentation/slimbus/summary

Should this file have a .rst extension, like other Restructured Text
files?

> @@ -0,0 +1,109 @@
> +Overview of Linux kernel SLIMbus support
> +========================================
[...]
> +Device notifications to the driver:
> +-----------------------------------
> +Since SLIMbus devices have mechanisms for reporting their presence, the
> +framework allows drivers to bind when corresponding devices report their
> +presence on the bus.
> +However, it is possible that the driver needs to be probed
> +first so that it can enable corresponding SLIMbus devie (e.g. power it up and/or

s/devie/device/ I guess

> +take it out of reset). To support that behavior, the framework allows drivers
> +to probe first as well  (e.g. using standard DeviceTree compatbility field).
> +This creates the necessity for the driver to know when the device is functional
> +(i.e. reported present). device_up callback is used for that reason when the
> +device reports present and is assigned a logical address by the controller.
[...]
> +/**
> + * struct slim_addrt: slimbus address used internally by the slimbus framework.
> + * @valid: If the device is present. Valid is set to false when device reports
> + *	absent.
> + * @eaddr: Enumeration address
> + * @laddr: It is possible that controller will set a predefined logical address
> + *	rather than the one assigned by framework. (i.e. logical address may
> + *	not be same as index into this table). This entry will store the
> + *	logical address value for this enumeration address.
> + */
> +struct slim_addrt {
> +	bool			valid;
> +	struct slim_eaddr	eaddr;
> +	u8			laddr;
> +};

I wonder if valid should be moved after eaddr, to reduce the need for
padding. AFAICS, struct slim_eaddr is 6 bytes long and requires 2-byte
alignment, so if valid is one byte long, there would be one byte of
padding after it, slightly bloating struct slim_addrt, unnecessarily.

> +/**
> + * struct slim_controller: Controls every instance of SLIMbus
> + *				(similar to 'master' on SPI)
> + *	'Manager device' is responsible for  device management, bandwidth
> + *	allocation, channel setup, and port associations per channel.
> + *	Device management means Logical address assignment/removal based on
> + *	enumeration (report-present, report-absent) if a device.

s/if a device/of a device/ ?

> + *	Bandwidth allocation is done dynamically by the manager based on active
> + *	channels on the bus, message-bandwidth requests made by slimbus devices.
> + *	Based on current bandwidth usage, manager chooses a frequency to run
> + *	the bus at (in steps of 'clock-gear', 1 through 10, each clock gear
> + *	representing twice the frequency than the previous gear).
> + *	Manager is also responsible for entering (and exiting) low-power-mode
> + *	(known as 'clock pause').
> + *	Manager can do handover of framer if there are multiple framers on the
> + *	bus and a certain usecase warrants using certain framer to avoid keeping
> + *	previous framer being powered-on.
> + *
> + *	Controller here performs duties of the manager device, and 'interface
> + *	device'. Interface device is responsible for monitoring the bus and
> + *	reporting information such as loss-of-synchronization, data
> + *	slot-collision.
> + * @dev: Device interface to this driver
> + * @nr: Board-specific number identifier for this controller/bus
> + * @list: Link with other slimbus controllers

I don't see list in the struct.

> + * @name: Name for this controller
> + * @min_cg: Minimum clock gear supported by this controller (default value: 1)
> + * @max_cg: Maximum clock gear supported by this controller (default value: 10)
> + * @clkgear: Current clock gear in which this bus is running
> + * @a_framer: Active framer which is clocking the bus managed by this controller
> + * @m_ctrl: Mutex protecting controller data structures
> + * @addrt: Logical address table
> + * @num_dev: Number of active slimbus slaves on this bus
> + * @wq: Workqueue per controller used to notify devices when they report present
> + * @xfer_msg: Transfer a message on this controller (this can be a broadcast
> + *	control/status message like data channel setup, or a unicast message
> + *	like value element read/write.

I don't see xfer_msg in the struct.

> + * @set_laddr: Setup logical address at laddr for the slave with elemental
> + *	address e_addr. Drivers implementing controller will be expected to
> + *	send unicast message to this device with its logical address.
> + * @get_laddr: It is possible that controller needs to set fixed logical
> + *	address table and get_laddr can be used in that case so that controller
> + *	can do this assignment.
> + */
> +struct slim_controller {
> +	struct device		dev;
> +	unsigned int		nr;
> +	char			name[SLIMBUS_NAME_SIZE];
> +	int			min_cg;
> +	int			max_cg;
> +	int			clkgear;
> +	struct slim_framer	*a_framer;
> +	struct mutex		m_ctrl;
> +	struct slim_addrt	*addrt;
> +	u8			num_dev;
> +	struct workqueue_struct *wq;
> +	int			(*set_laddr)(struct slim_controller *ctrl,
> +					     struct slim_eaddr *ea, u8 laddr);
> +	int			(*get_laddr)(struct slim_controller *ctrl,
> +					     struct slim_eaddr *ea, u8 *laddr);
> +};


Thanks,
Jonathan Neuschäfer

Thanks for the comments.

On 07/10/17 05:14, Jonathan Neuschäfer wrote:
> Hi, I have some more or less trivial comments below.
> 
> On Fri, Oct 06, 2017 at 05:51:30PM +0200, srinivas.kandagatla@linaro.org wrote:
>> From: Sagar Dharia <sdharia@codeaurora.org>
>>
>> SLIMbus (Serial Low Power Interchip Media Bus) is a specification
>> developed by MIPI (Mobile Industry Processor Interface) alliance.
>> SLIMbus is a 2-wire implementation, which is used to communicate with
>> peripheral components like audio-codec.
>> SLIMbus uses Time-Division-Multiplexing to accommodate multiple data
>> channels, and control channel. Control channel has messages to do
>> device-enumeration, messages to send/receive control-data to/from
>> slimbus devices, messages for port/channel management, and messages to
>> do bandwidth allocation.
>> The framework supports multiple instances of the bus (1 controller per
>> bus), and multiple slave devices per controller.
>>
>> This patch does device enumeration, logical address assignment,
>> informing device when the device reports present/absent etc.
>> Reporting present may need the driver to do the needful (e.g. turning
>> on voltage regulators powering the device). Additionally device is
>> probed when it reports present if that device doesn't need any such
>> steps mentioned above.
>>
>> Signed-off-by: Sagar Dharia <sdharia@codeaurora.org>
>> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
>> ---
> [...]
>> +SLIMbus example for Qualcomm's slimbus manager component:
>> +
>> +	slim@28080000 {
>> +		compatible = "qcom,slim-msm";
>> +		reg = <0x28080000 0x2000>,
>> +		interrupts = <0 33 0>;
>> +		clocks = <&lcc SLIMBUS_SRC>, <&lcc AUDIO_SLIMBUS_CLK>;
>> +		clock-names = "iface_clk", "core_clk";
>> +		#address-cells = <2>;
>> +		#size-cells = <0>;
>> +
>> +		codec: wcd9310@1{
>> +			compatible = "slim217,60"";
> 			                        ^ spurious quote?
> 
>> +			reg = <1 0>;
>> +		};
>> +	};
>> diff --git a/Documentation/slimbus/summary b/Documentation/slimbus/summary
>> new file mode 100644
>> index 0000000..e7f90bb
>> --- /dev/null
>> +++ b/Documentation/slimbus/summary
> 
> Should this file have a .rst extension, like other Restructured Text
> files?

Will try to sort this out in next version.

> 
>> @@ -0,0 +1,109 @@
>> +Overview of Linux kernel SLIMbus support
>> +========================================
> [...]
>> +Device notifications to the driver:
>> +-----------------------------------
>> +Since SLIMbus devices have mechanisms for reporting their presence, the
>> +framework allows drivers to bind when corresponding devices report their
>> +presence on the bus.
>> +However, it is possible that the driver needs to be probed
>> +first so that it can enable corresponding SLIMbus devie (e.g. power it up and/or
> 
> s/devie/device/ I guess
> 
>> +take it out of reset). To support that behavior, the framework allows drivers
>> +to probe first as well  (e.g. using standard DeviceTree compatbility field).
>> +This creates the necessity for the driver to know when the device is functional
>> +(i.e. reported present). device_up callback is used for that reason when the
>> +device reports present and is assigned a logical address by the controller.
> [...]
>> +/**
>> + * struct slim_addrt: slimbus address used internally by the slimbus framework.
>> + * @valid: If the device is present. Valid is set to false when device reports
>> + *	absent.
>> + * @eaddr: Enumeration address
>> + * @laddr: It is possible that controller will set a predefined logical address
>> + *	rather than the one assigned by framework. (i.e. logical address may
>> + *	not be same as index into this table). This entry will store the
>> + *	logical address value for this enumeration address.
>> + */
>> +struct slim_addrt {
>> +	bool			valid;
>> +	struct slim_eaddr	eaddr;
>> +	u8			laddr;
>> +};
> 
> I wonder if valid should be moved after eaddr, to reduce the need for
> padding. AFAICS, struct slim_eaddr is 6 bytes long and requires 2-byte
> alignment, so if valid is one byte long, there would be one byte of
> padding after it, slightly bloating struct slim_addrt, unnecessarily.
Makes sense!!

> 
>> +/**
>> + * struct slim_controller: Controls every instance of SLIMbus
>> + *				(similar to 'master' on SPI)
>> + *	'Manager device' is responsible for  device management, bandwidth
>> + *	allocation, channel setup, and port associations per channel.
>> + *	Device management means Logical address assignment/removal based on
>> + *	enumeration (report-present, report-absent) if a device.
> 

> s/if a device/of a device/ ?

Yep, will fix this in next version.
> 
>> + *	Bandwidth allocation is done dynamically by the manager based on active
>> + *	channels on the bus, message-bandwidth requests made by slimbus devices.
>> + *	Based on current bandwidth usage, manager chooses a frequency to run
>> + *	the bus at (in steps of 'clock-gear', 1 through 10, each clock gear
>> + *	representing twice the frequency than the previous gear).
>> + *	Manager is also responsible for entering (and exiting) low-power-mode
>> + *	(known as 'clock pause').
>> + *	Manager can do handover of framer if there are multiple framers on the
>> + *	bus and a certain usecase warrants using certain framer to avoid keeping
>> + *	previous framer being powered-on.
>> + *
>> + *	Controller here performs duties of the manager device, and 'interface
>> + *	device'. Interface device is responsible for monitoring the bus and
>> + *	reporting information such as loss-of-synchronization, data
>> + *	slot-collision.
>> + * @dev: Device interface to this driver
>> + * @nr: Board-specific number identifier for this controller/bus
>> + * @list: Link with other slimbus controllers
> 
> I don't see list in the struct.
I think its a left over of the cleanup.. will fix this in next version.
> 
>> + * @name: Name for this controller
>> + * @min_cg: Minimum clock gear supported by this controller (default value: 1)
>> + * @max_cg: Maximum clock gear supported by this controller (default value: 10)
>> + * @clkgear: Current clock gear in which this bus is running
>> + * @a_framer: Active framer which is clocking the bus managed by this controller
>> + * @m_ctrl: Mutex protecting controller data structures
>> + * @addrt: Logical address table
>> + * @num_dev: Number of active slimbus slaves on this bus
>> + * @wq: Workqueue per controller used to notify devices when they report present
>> + * @xfer_msg: Transfer a message on this controller (this can be a broadcast
>> + *	control/status message like data channel setup, or a unicast message
>> + *	like value element read/write.
> 
> I don't see xfer_msg in the struct.
Will add in next version.

> 
>> + * @set_laddr: Setup logical address at laddr for the slave with elemental
>> + *	address e_addr. Drivers implementing controller will be expected to
>> + *	send unicast message to this device with its logical address.
>> + * @get_laddr: It is possible that controller needs to set fixed logical
>> + *	address table and get_laddr can be used in that case so that controller
>> + *	can do this assignment.
>> + */
>> +struct slim_controller {
>> +	struct device		dev;
>> +	unsigned int		nr;
>> +	char			name[SLIMBUS_NAME_SIZE];
>> +	int			min_cg;
>> +	int			max_cg;
>> +	int			clkgear;
>> +	struct slim_framer	*a_framer;
>> +	struct mutex		m_ctrl;
>> +	struct slim_addrt	*addrt;
>> +	u8			num_dev;
>> +	struct workqueue_struct *wq;
>> +	int			(*set_laddr)(struct slim_controller *ctrl,
>> +					     struct slim_eaddr *ea, u8 laddr);
>> +	int			(*get_laddr)(struct slim_controller *ctrl,
>> +					     struct slim_eaddr *ea, u8 *laddr);
>> +};
> 
> 
> Thanks,
> Jonathan Neuschäfer
> 
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On Fri, Oct 06, 2017 at 05:51:30PM +0200, srinivas.kandagatla@linaro.org wrote:
> From: Sagar Dharia <sdharia@codeaurora.org>
> 
> SLIMbus (Serial Low Power Interchip Media Bus) is a specification
> developed by MIPI (Mobile Industry Processor Interface) alliance.
> SLIMbus is a 2-wire implementation, which is used to communicate with
> peripheral components like audio-codec.
> SLIMbus uses Time-Division-Multiplexing to accommodate multiple data
> channels, and control channel. Control channel has messages to do
> device-enumeration, messages to send/receive control-data to/from
> slimbus devices, messages for port/channel management, and messages to
> do bandwidth allocation.
> The framework supports multiple instances of the bus (1 controller per
> bus), and multiple slave devices per controller.
> 
> This patch does device enumeration, logical address assignment,
> informing device when the device reports present/absent etc.
> Reporting present may need the driver to do the needful (e.g. turning
> on voltage regulators powering the device). Additionally device is
> probed when it reports present if that device doesn't need any such
> steps mentioned above.
> 
> Signed-off-by: Sagar Dharia <sdharia@codeaurora.org>
> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
> ---
>  Documentation/devicetree/bindings/slimbus/bus.txt |  57 ++
>  Documentation/slimbus/summary                     | 109 ++++
>  drivers/Kconfig                                   |   2 +
>  drivers/Makefile                                  |   1 +
>  drivers/slimbus/Kconfig                           |  11 +
>  drivers/slimbus/Makefile                          |   5 +
>  drivers/slimbus/slim-core.c                       | 695 ++++++++++++++++++++++
>  include/linux/mod_devicetable.h                   |  13 +
>  include/linux/slimbus.h                           | 299 ++++++++++
>  9 files changed, 1192 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/slimbus/bus.txt
>  create mode 100644 Documentation/slimbus/summary
>  create mode 100644 drivers/slimbus/Kconfig
>  create mode 100644 drivers/slimbus/Makefile
>  create mode 100644 drivers/slimbus/slim-core.c
>  create mode 100644 include/linux/slimbus.h
> 
> diff --git a/Documentation/devicetree/bindings/slimbus/bus.txt b/Documentation/devicetree/bindings/slimbus/bus.txt
> new file mode 100644
> index 0000000..cb658bb
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/slimbus/bus.txt
> @@ -0,0 +1,57 @@
> +SLIM(Serial Low Power Interchip Media Bus) bus
> +
> +SLIMbus is a 2-wire bus, and is used to communicate with peripheral
> +components like audio-codec.
> +
> +Controller is a normal device using binding for whatever bus it is
> +on (e.g. platform bus).
> +Required property for SLIMbus controller node:
> +- compatible	- name of SLIMbus controller following generic names
> +		recommended practice.
> +- #address-cells - should be 2
> +- #size-cells	- should be 0
> +
> +No other properties are required in the SLIMbus controller bus node.
> +
> +Child nodes:
> +Every SLIMbus controller node can contain zero or more child nodes
> +representing slave devices on the bus. Every SLIMbus slave device is
> +uniquely determined by the enumeration address containing 4 fields:
> +Manufacturer ID, Product code, Device index, and Instance value for
> +the device.
> +If child node is not present and it is instantiated after device
> +discovery (slave device reporting itself present).
> +
> +In some cases it may be necessary to describe non-probeable device
> +details such as non-standard ways of powering up a device. In
> +such cases, child nodes for those devices will be present as
> +slaves of the slimbus-controller, as detailed below.
> +
> +Required property for SLIMbus child node if it is present:
> +- reg		- Is Duplex (Device index, Instance ID) from Enumeration
> +		  Address.
> +		  Device Index Uniquely identifies multiple Devices within
> +		  a single Component.
> +		  Instance ID Is for the cases where multiple Devices of the
> +		  same type or Class are attached to the bus.
> +
> +- compatible	-"slimMID,PID". The textual representation of Manufacturer ID,
> +	 	  Product Code, shall be in lower case hexadecimal with leading
> +		  zeroes suppressed

This does sort of make sense but kinda makes the code a bit ugly
parsing the MID and PID. Some parts will support SLIMBus and also
other control interfaces, which means they would need to add an
additional compatible string just for SLIMBus. It also breaks
the normal conventions of vendor,part and finally it makes the
compatible strings really unreadable which will be a bit annoying
when looking at DTs.

I think the MID and PID should just be included in the reg field
and just leave this as a standard compatible.

> +/**

This doesn't appear to be a kernel doc comment, so only /*.

> + * Report callbacks(device_up, device_down) are implemented by slimbus-devices.
> + * The calls are scheduled into a workqueue to avoid holding up controller
> + * initialization/tear-down.
> + */
> +static void schedule_slim_report(struct slim_controller *ctrl,
> +				 struct slim_device *sb, bool report)
> +{
> +	struct sb_report_wd *sbw;
> +
> +	dev_dbg(&ctrl->dev, "report:%d for slave:%s\n", report, sb->name);
> +
> +	sbw = kmalloc(sizeof(*sbw), GFP_KERNEL);
> +	if (!sbw)
> +		return;
> +
> +	INIT_WORK(&sbw->wd, slim_report);
> +	sbw->sbdev = sb;
> +	sbw->report = report;
> +	if (!queue_work(ctrl->wq, &sbw->wd)) {
> +		dev_err(&ctrl->dev, "failed to queue report:%d slave:%s\n",
> +				    report, sb->name);
> +		kfree(sbw);
> +	}
> +}
> +
> +/**
> + * slim_driver_register: Client driver registration with slimbus

A - after the function name usually works better, I think
kernel-doc doesn't support a colon after the function name.

> + * @drv:Client driver to be associated with client-device.
> + * @owner: owning module/driver
> + * This API will register the client driver with the slimbus
> + * It is called from the driver's module-init function.

If you don't put a blank line after the arguments kernel doc will
treat this as a run on for the description of owner rather than
the long description for the function you intended it to be.

> +
> +/* Helper to get hex Manufacturer ID and Product id from compatible */
> +static unsigned long str2hex(unsigned char *str)
> +{
> +	int value = 0;
> +
> +	while (*str) {
> +		char c = *str++;
> +
> +		value = value << 4;
> +		if (c >= '0' && c <= '9')
> +			value |= (c - '0');
> +		if (c >= 'a' && c <= 'f')
> +			value |= (c - 'a' + 10);
> +
> +	}
> +
> +	return value;
> +}

Isn't this just reimplementing kstrtoul?

> +
> +/* OF helpers for SLIMbus */
> +static void of_register_slim_devices(struct slim_controller *ctrl)
> +{
> +	struct device *dev = &ctrl->dev;
> +	struct device_node *node;
> +
> +	if (!ctrl->dev.of_node)
> +		return;
> +
> +	for_each_child_of_node(ctrl->dev.of_node, node) {
> +		struct slim_device *slim;
> +		const char *compat = NULL;
> +		char *p, *tok;
> +		int reg[2], ret;
> +
> +		slim = kzalloc(sizeof(*slim), GFP_KERNEL);
> +		if (!slim)
> +			continue;
> +
> +		slim->dev.of_node = of_node_get(node);
> +
> +		compat = of_get_property(node, "compatible", NULL);
> +		if (!compat)
> +			continue;
> +
> +		p = kasprintf(GFP_KERNEL, "%s", compat + strlen("slim"));
> +
> +		tok = strsep(&p, ",");
> +		if (!tok) {
> +			dev_err(dev, "No valid Manufacturer ID found\n");
> +			kfree(p);
> +			continue;
> +		}
> +		slim->e_addr.manf_id = str2hex(tok);
> +
> +		tok = strsep(&p, ",");
> +		if (!tok) {
> +			dev_err(dev, "No valid Product ID found\n");
> +			kfree(p);
> +			continue;
> +		}
> +		slim->e_addr.prod_code = str2hex(tok);
> +		kfree(p);
> +
> +		ret = of_property_read_u32_array(node, "reg", reg, 2);
> +		if (ret) {
> +			dev_err(dev, "Device and Instance id not found:%d\n",
> +				ret);
> +			continue;
> +		}
> +		slim->e_addr.dev_index = reg[0];
> +		slim->e_addr.instance = reg[1];

As I said above, this feels a bit complex compared to just
reading the e_addr from reg.

> +
> +		ret = slim_add_device(ctrl, slim);
> +		if (ret)
> +			dev_err(dev, "of_slim device register err:%d\n", ret);
> +	}
> +}

> +
> +static int slim_boot_child(struct device *dev, void *unused)
> +{
> +	struct slim_driver *sbdrv;
> +	struct slim_device *sbdev = to_slim_device(dev);
> +
> +	if (sbdev && sbdev->dev.driver) {
> +		sbdrv = to_slim_driver(sbdev->dev.driver);
> +		if (sbdrv->boot_device)
> +			sbdrv->boot_device(sbdev);
> +	}
> +	return 0;
> +}
> +
> +static int slim_match_dev(struct device *dev, void *data)
> +{
> +	struct slim_eaddr *e_addr = data;
> +	struct slim_device *slim = to_slim_device(dev);
> +
> +	return slim_eaddr_equal(&slim->e_addr, e_addr);
> +}

Would it make sense to move this down to above slim_query_device,
that way all the related code is next to itself?
slim_boot_child/slim_framer_booted and
slim_match_dev/slim_query_device.

> +
> +/**
> + * slim_framer_booted: This function is called by controller after the active
> + * framer has booted (using Bus Reset sequence, or after it has shutdown and has
> + * come back up).
> + * @ctrl: Controller associated with this framer
> + * Components, devices on the bus may be in undefined state,
> + * and this function triggers their drivers to do the needful
> + * to bring them back in Reset state so that they can acquire sync, report
> + * present and be operational again.
> + */
> +void slim_framer_booted(struct slim_controller *ctrl)
> +{
> +	if (!ctrl)
> +		return;
> +
> +	device_for_each_child(&ctrl->dev, NULL, slim_boot_child);
> +}
> +EXPORT_SYMBOL_GPL(slim_framer_booted);
> +
> +/**
> + * slim_query_device: Query and get handle to a device.
> + * @ctrl: Controller on which this device will be added/queried
> + * @e_addr: Enumeration address of the device to be queried
> + * Returns pointer to a device if it has already reported. Creates a new
> + * device and returns pointer to it if the device has not yet enumerated.
> + */
> +struct slim_device *slim_query_device(struct slim_controller *ctrl,
> +				      struct slim_eaddr *e_addr)
> +{
> +	struct device *dev;
> +	struct slim_device *slim = NULL;
> +
> +	dev = device_find_child(&ctrl->dev, e_addr, slim_match_dev);
> +	if (dev) {
> +		slim = to_slim_device(dev);
> +		return slim;
> +	}
> +
> +	slim = kzalloc(sizeof(struct slim_device), GFP_KERNEL);
> +	if (IS_ERR(slim))
> +		return NULL;
> +
> +	slim->e_addr = *e_addr;
> +	if (slim_add_device(ctrl, slim) != 0) {
> +		kfree(slim);
> +		return NULL;
> +	}
> +	return slim;
> +}
> +EXPORT_SYMBOL_GPL(slim_query_device);
> +
> +static int ctrl_getaddr_entry(struct slim_controller *ctrl,
> +			      struct slim_eaddr *eaddr, u8 *entry)
> +{
> +	int i;
> +
> +	for (i = 0; i < ctrl->num_dev; i++) {
> +		if (ctrl->addrt[i].valid &&
> +		    slim_eaddr_equal(&ctrl->addrt[i].eaddr, eaddr)) {
> +			*entry = i;
> +			return 0;
> +		}
> +	}
> +	return -ENXIO;
> +}
> +
> +/**
> + * slim_assign_laddr: Assign logical address to a device enumerated.
> + * @ctrl: Controller with which device is enumerated.
> + * @e_addr: Enumeration address of the device.
> + * @laddr: Return logical address (if valid flag is false)
> + * @valid: true if laddr holds a valid address that controller wants to
> + *	set for this enumeration address. Otherwise framework sets index into
> + *	address table as logical address.
> + * Called by controller in response to REPORT_PRESENT. Framework will assign
> + * a logical address to this enumeration address.
> + * Function returns -EXFULL to indicate that all logical addresses are already
> + * taken.
> + */
> +int slim_assign_laddr(struct slim_controller *ctrl, struct slim_eaddr *e_addr,
> +		      u8 *laddr, bool valid)

I would be inclined to remove the valid parameter and just
use get_laddr in here.  Feels weird to have two mechanisms
for specify the laddr and presumably if the controller wants
to specify the laddr it will need to support get_laddr.
Additionally, I would make get_laddr optional which feels more
sensible, indeed the code appears otherwise implements with that
assumption.

> +{
> +	int ret;
> +	u8 i = 0;
> +	bool exists = false;
> +	struct slim_device *slim;
> +	struct slim_addrt *temp;
> +
> +	mutex_lock(&ctrl->m_ctrl);
> +	/* already assigned */
> +	if (ctrl_getaddr_entry(ctrl, e_addr, &i) == 0) {
> +		*laddr = ctrl->addrt[i].laddr;
> +		exists = true;
> +	} else {
> +		if (ctrl->num_dev >= (SLIM_LA_MANAGER - 1)) {
> +			ret = -EXFULL;
> +			goto ret_assigned_laddr;
> +		}
> +		for (i = 0; i < ctrl->num_dev; i++) {
> +			if (ctrl->addrt[i].valid == false)
> +				break;
> +		}
> +		if (i == ctrl->num_dev) {
> +			temp = krealloc(ctrl->addrt,
> +					(ctrl->num_dev + 1) *
> +					sizeof(struct slim_addrt),
> +					GFP_KERNEL);
> +			if (!temp) {
> +				ret = -ENOMEM;
> +				goto ret_assigned_laddr;
> +			}
> +			ctrl->addrt = temp;
> +			ctrl->num_dev++;
> +		}
> +		ctrl->addrt[i].eaddr = *e_addr;
> +		ctrl->addrt[i].valid = true;
> +
> +		/* Preferred address is index into table */
> +		if (!valid)
> +			*laddr = i;
> +	}
> +
> +	ret = ctrl->set_laddr(ctrl, &ctrl->addrt[i].eaddr, *laddr);
> +	if (ret) {
> +		ctrl->addrt[i].valid = false;
> +		goto ret_assigned_laddr;
> +	}
> +	ctrl->addrt[i].laddr = *laddr;
> +
> +ret_assigned_laddr:
> +	mutex_unlock(&ctrl->m_ctrl);
> +	if (exists || ret)
> +		return ret;
> +
> +	dev_info(&ctrl->dev, "setting slimbus l-addr:%x, ea:%x,%x,%x,%x\n",
> +		*laddr, e_addr->manf_id, e_addr->prod_code,
> +		e_addr->dev_index, e_addr->instance);
> +
> +	/**
> +	 * Add this device to list of devices on this controller if it's
> +	 * not already present
> +	 */
> +	slim = slim_query_device(ctrl, e_addr);
> +	if (!slim) {
> +		ret = -ENODEV;
> +	} else {
> +		struct slim_driver *sbdrv;
> +
> +		slim->laddr = *laddr;
> +		mutex_lock(&slim->report_lock);
> +		slim->reported = true;
> +		if (slim->dev.driver) {
> +			sbdrv = to_slim_driver(slim->dev.driver);
> +			if (sbdrv->device_up)
> +				schedule_slim_report(ctrl, slim, true);
> +		}
> +		mutex_unlock(&slim->report_lock);
> +	}
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(slim_assign_laddr);
> +
> +/**
> + * slim_get_logical_addr: Return the logical address of a slimbus device.
> + * @sb: client handle requesting the address.
> + * @e_addr: Enumeration address of the device.
> + * @laddr: output buffer to store the address
> + * context: can sleep
> + * -EINVAL is returned in case of invalid parameters, and -ENXIO is returned if
> + *  the device with this enumeration address is not found.
> + */
> +int slim_get_logical_addr(struct slim_device *sb, struct slim_eaddr *e_addr,
> +			  u8 *laddr)
> +{
> +	int ret;
> +	u8 entry;
> +	struct slim_controller *ctrl = sb->ctrl;
> +
> +	if (!ctrl || !laddr || !e_addr)
> +		return -EINVAL;
> +
> +	mutex_lock(&ctrl->m_ctrl);
> +	ret = ctrl_getaddr_entry(ctrl, e_addr, &entry);
> +	if (!ret)
> +		*laddr = ctrl->addrt[entry].laddr;
> +	mutex_unlock(&ctrl->m_ctrl);
> +
> +	if (ret == -ENXIO && ctrl->get_laddr) {
> +		ret = ctrl->get_laddr(ctrl, e_addr, laddr);
> +		if (!ret)
> +			ret = slim_assign_laddr(ctrl, e_addr, laddr, true);
> +	}
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(slim_get_logical_addr);

I find the interface across these two functions
(assign_laddr/get_logical_addr) a little odd. Since
get_logical_addr calls assign_laddr if it couldn't find the
laddr and then assign_laddr actually does another search for the
laddr. Would it perhaps make sense to combine these into one
function?

Thanks,
Charles
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On Fri, Oct 06, 2017 at 05:51:30PM +0200, srinivas.kandagatla@linaro.org wrote:
> From: Sagar Dharia <sdharia@codeaurora.org>
> 
> SLIMbus (Serial Low Power Interchip Media Bus) is a specification
> developed by MIPI (Mobile Industry Processor Interface) alliance.
> SLIMbus is a 2-wire implementation, which is used to communicate with
> peripheral components like audio-codec.
> SLIMbus uses Time-Division-Multiplexing to accommodate multiple data
> channels, and control channel. Control channel has messages to do
> device-enumeration, messages to send/receive control-data to/from
> slimbus devices, messages for port/channel management, and messages to
> do bandwidth allocation.
> The framework supports multiple instances of the bus (1 controller per
> bus), and multiple slave devices per controller.
> 
> This patch does device enumeration, logical address assignment,
> informing device when the device reports present/absent etc.
> Reporting present may need the driver to do the needful (e.g. turning
> on voltage regulators powering the device). Additionally device is
> probed when it reports present if that device doesn't need any such
> steps mentioned above.
> 
> Signed-off-by: Sagar Dharia <sdharia@codeaurora.org>
> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
> ---
>  Documentation/devicetree/bindings/slimbus/bus.txt |  57 ++
>  Documentation/slimbus/summary                     | 109 ++++
>  drivers/Kconfig                                   |   2 +
>  drivers/Makefile                                  |   1 +
>  drivers/slimbus/Kconfig                           |  11 +
>  drivers/slimbus/Makefile                          |   5 +
>  drivers/slimbus/slim-core.c                       | 695 ++++++++++++++++++++++
>  include/linux/mod_devicetable.h                   |  13 +
>  include/linux/slimbus.h                           | 299 ++++++++++
>  9 files changed, 1192 insertions(+)

thats a lot of code for review, consider splitting it up further for better
reviews

>  create mode 100644 Documentation/devicetree/bindings/slimbus/bus.txt
>  create mode 100644 Documentation/slimbus/summary
>  create mode 100644 drivers/slimbus/Kconfig
>  create mode 100644 drivers/slimbus/Makefile
>  create mode 100644 drivers/slimbus/slim-core.c

how about core.c (https://lkml.org/lkml/2017/7/12/430)

> +static const struct slim_device_id *slim_match(const struct slim_device_id *id,
> +					       const struct slim_device *sbdev)
> +{
> +	while (id->manf_id != 0 || id->prod_code != 0) {
> +		if (id->manf_id == sbdev->e_addr.manf_id &&
> +		    id->prod_code == sbdev->e_addr.prod_code &&
> +		    id->dev_index == sbdev->e_addr.dev_index)
> +			return id;
> +		id++;
> +	}
> +	return NULL;
> +}
> +
> +static int slim_device_match(struct device *dev, struct device_driver *drv)
> +{
> +	struct slim_device *sbdev = to_slim_device(dev);
> +	struct slim_driver *sbdrv = to_slim_driver(drv);
> +
> +	/* Attempt an OF style match first */
> +	if (of_driver_match_device(dev, drv))
> +		return 1;

is of_driver_match_device() a must have here? (I dont completely understand
DT so pardon my ignorance). Since we have devices with ids can we use that
alone for matching?

> +
> +	/* Then try to match against the id table */
> +	if (sbdrv->id_table)
> +		return slim_match(sbdrv->id_table, sbdev) != NULL;
> +
> +	return 0;
> +}
> +

rather than jumping now to reporting APIs, can we club all bus_type parts to
one place (patch) so that it is easier to review logically

> +struct sb_report_wd {
> +	struct work_struct wd;
> +	struct slim_device *sbdev;
> +	bool report;
> +};
> +
> +static void slim_report(struct work_struct *work)
> +{
> +	struct slim_driver *sbdrv;
> +	struct sb_report_wd *sbw = container_of(work, struct sb_report_wd, wd);
> +	struct slim_device *sbdev = sbw->sbdev;
> +
> +	mutex_lock(&sbdev->report_lock);
> +	if (!sbdev->dev.driver)
> +		goto report_exit;
> +
> +	/* check if device-up or down needs to be called */
> +	if ((!sbdev->reported && !sbdev->notified) ||
> +	    (sbdev->reported && sbdev->notified))
> +		goto report_exit;
> +
> +	sbdrv = to_slim_driver(sbdev->dev.driver);
> +
> +	/**
> +	 * address no longer valid, means device reported absent, whereas
> +	 * address valid, means device reported present
> +	 */

I think ppl commented about this style, so lets fix those issues

> +	if (sbdev->notified && !sbdev->reported) {
> +		sbdev->notified = false;
> +		if (sbdrv->device_down)
> +			sbdrv->device_down(sbdev);
> +	} else if (!sbdev->notified && sbdev->reported) {
> +		sbdev->notified = true;
> +		if (sbdrv->device_up)
> +			sbdrv->device_up(sbdev);

what do the device_up/down calls signify here?

> +static int slim_device_probe(struct device *dev)
> +{
> +	struct slim_device	*sbdev;
> +	struct slim_driver	*sbdrv;
> +	int status = 0;
> +
> +	sbdev = to_slim_device(dev);
> +	sbdrv = to_slim_driver(dev->driver);
> +
> +	sbdev->driver = sbdrv;
> +
> +	if (sbdrv->probe)
> +		status = sbdrv->probe(sbdev);
> +
> +	if (status)
> +		sbdev->driver = NULL;
> +	else if (sbdrv->device_up)
> +		schedule_slim_report(sbdev->ctrl, sbdev, true);

can you please explain what this is trying to do?

> +int __slim_driver_register(struct slim_driver *drv, struct module *owner)
> +{
> +	drv->driver.bus = &slimbus_type;
> +	drv->driver.owner = owner;
> +	return driver_register(&drv->driver);
> +}
> +EXPORT_SYMBOL_GPL(__slim_driver_register);

any reason to use __ for this API?

> +static int slim_add_device(struct slim_controller *ctrl,
> +			   struct slim_device *sbdev)
> +{
> +	sbdev->dev.bus = &slimbus_type;
> +	sbdev->dev.parent = &ctrl->dev;
> +	sbdev->dev.release = slim_dev_release;
> +	sbdev->dev.driver = NULL;
> +	sbdev->ctrl = ctrl;
> +
> +	slim_ctrl_get(ctrl);
> +	sbdev->name = kasprintf(GFP_KERNEL, "%x:%x:%x:%x",
> +					sbdev->e_addr.manf_id,
> +					sbdev->e_addr.prod_code,
> +					sbdev->e_addr.dev_index,
> +					sbdev->e_addr.instance);
> +	if (!sbdev->name)
> +		return -ENOMEM;
> +
> +	dev_set_name(&sbdev->dev, "%s", sbdev->name);
> +	mutex_init(&sbdev->report_lock);
> +
> +	/* probe slave on this controller */
> +	return device_register(&sbdev->dev);

I dont think the comment is quite correct, you register a device not probe!

> +/* OF helpers for SLIMbus */
> +static void of_register_slim_devices(struct slim_controller *ctrl)
> +{
> +	struct device *dev = &ctrl->dev;
> +	struct device_node *node;
> +
> +	if (!ctrl->dev.of_node)
> +		return;
> +
> +	for_each_child_of_node(ctrl->dev.of_node, node) {
> +		struct slim_device *slim;
> +		const char *compat = NULL;
> +		char *p, *tok;
> +		int reg[2], ret;
> +
> +		slim = kzalloc(sizeof(*slim), GFP_KERNEL);
> +		if (!slim)
> +			continue;
> +
> +		slim->dev.of_node = of_node_get(node);
> +
> +		compat = of_get_property(node, "compatible", NULL);
> +		if (!compat)
> +			continue;
> +
> +		p = kasprintf(GFP_KERNEL, "%s", compat + strlen("slim"));
> +
> +		tok = strsep(&p, ",");
> +		if (!tok) {
> +			dev_err(dev, "No valid Manufacturer ID found\n");
> +			kfree(p);
> +			continue;
> +		}
> +		slim->e_addr.manf_id = str2hex(tok);
> +
> +		tok = strsep(&p, ",");
> +		if (!tok) {
> +			dev_err(dev, "No valid Product ID found\n");
> +			kfree(p);
> +			continue;
> +		}
> +		slim->e_addr.prod_code = str2hex(tok);
> +		kfree(p);
> +
> +		ret = of_property_read_u32_array(node, "reg", reg, 2);
> +		if (ret) {
> +			dev_err(dev, "Device and Instance id not found:%d\n",
> +				ret);
> +			continue;
> +		}
> +		slim->e_addr.dev_index = reg[0];
> +		slim->e_addr.instance = reg[1];
> +
> +		ret = slim_add_device(ctrl, slim);

okay this is good stuff. So we scan the DT for slimbus devices and register
them here. Same stuff we can do with ACPI :)

then why do we need the of register stuff I commented earlier. A Slimbus
device can work irrespective of firmware type and registers using various
ids. The platform will scan firmware (dt/acpi) create devices and load
drivers against them generically.  Apart from this code we ideally should
not have any DT parts in the bus, do you agree?

> +		if (ret)
> +			dev_err(dev, "of_slim device register err:%d\n", ret);
> +	}
> +}
> +
> +/**
> + * slim_register_controller: Controller bring-up and registration.
> + * @ctrl: Controller to be registered.
> + * A controller is registered with the framework using this API.
> + * If devices on a controller were registered before controller,
> + * this will make sure that they get probed when controller is up
> + */
> +int slim_register_controller(struct slim_controller *ctrl)
> +{
> +	int id, ret = 0;
> +
> +	mutex_lock(&slim_lock);
> +	id = idr_alloc(&ctrl_idr, ctrl, ctrl->nr, -1, GFP_KERNEL);

what are these ids used for?

> +	mutex_unlock(&slim_lock);
> +
> +	if (id < 0)
> +		return id;
> +
> +	ctrl->nr = id;
> +
> +	dev_set_name(&ctrl->dev, "sb-%d", ctrl->nr);
> +	ctrl->num_dev = 0;
> +
> +	if (!ctrl->min_cg)
> +		ctrl->min_cg = SLIM_MIN_CLK_GEAR;
> +	if (!ctrl->max_cg)
> +		ctrl->max_cg = SLIM_MAX_CLK_GEAR;
> +
> +	mutex_init(&ctrl->m_ctrl);
> +	ret = device_register(&ctrl->dev);

one more device_register?? Can you explain why

> +/**
> + * struct slim_addrt: slimbus address used internally by the slimbus framework.
> + * @valid: If the device is present. Valid is set to false when device reports
> + *	absent.
> + * @eaddr: Enumeration address
> + * @laddr: It is possible that controller will set a predefined logical address
> + *	rather than the one assigned by framework. (i.e. logical address may
> + *	not be same as index into this table). This entry will store the
> + *	logical address value for this enumeration address.
> + */
> +struct slim_addrt {

addrt? why not just addr?

> +	bool			valid;
> +	struct slim_eaddr	eaddr;
> +	u8			laddr;
> +};
> +
> +/* SLIMbus message types. Related to interpretation of message code. */
> +#define SLIM_MSG_MT_CORE			0x0
> +#define SLIM_MSG_MT_DEST_REFERRED_CLASS		0x1
> +#define SLIM_MSG_MT_DEST_REFERRED_USER		0x2
> +#define SLIM_MSG_MT_SRC_REFERRED_CLASS		0x5
> +#define SLIM_MSG_MT_SRC_REFERRED_USER		0x6

BIT() GENMASK() please here and other places where they define bits in spec

> +/**
> + * struct slim_driver: Slimbus 'generic device' (slave) device driver
> + *				(similar to 'spi_device' on SPI)
> + * @probe: Binds this driver to a slimbus device.
> + * @remove: Unbinds this driver from the slimbus device.
> + * @shutdown: Standard shutdown callback used during powerdown/halt.
> + * @suspend: Standard suspend callback used during system suspend
> + * @resume: Standard resume callback used during system resume
> + * @device_up: This callback is called when the device reports present and
> + *		gets a logical address assigned to it
> + * @device_down: This callback is called when device reports absent, or the
> + *		bus goes down. Device will report present when bus is up and
> + *		device_up callback will be called again when that happens

do we need two callback, why not a status or notify callback with argument
for up/down?

Thanks for the review comments.

On 10/10/17 11:05, Charles Keepax wrote:
> On Fri, Oct 06, 2017 at 05:51:30PM +0200, srinivas.kandagatla@linaro.org wrote:
>> From: Sagar Dharia <sdharia@codeaurora.org>
>>
>> SLIMbus (Serial Low Power Interchip Media Bus) is a specification
>> developed by MIPI (Mobile Industry Processor Interface) alliance.
>> SLIMbus is a 2-wire implementation, which is used to communicate with
>> peripheral components like audio-codec.
>> SLIMbus uses Time-Division-Multiplexing to accommodate multiple data
>> channels, and control channel. Control channel has messages to do
>> device-enumeration, messages to send/receive control-data to/from
>> slimbus devices, messages for port/channel management, and messages to
>> do bandwidth allocation.
>> The framework supports multiple instances of the bus (1 controller per
>> bus), and multiple slave devices per controller.
>>
>> This patch does device enumeration, logical address assignment,
>> informing device when the device reports present/absent etc.
>> Reporting present may need the driver to do the needful (e.g. turning
>> on voltage regulators powering the device). Additionally device is
>> probed when it reports present if that device doesn't need any such
>> steps mentioned above.
>>
>> Signed-off-by: Sagar Dharia <sdharia@codeaurora.org>
>> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
>> ---
>>   Documentation/devicetree/bindings/slimbus/bus.txt |  57 ++
>>   Documentation/slimbus/summary                     | 109 ++++
>>   drivers/Kconfig                                   |   2 +
>>   drivers/Makefile                                  |   1 +
>>   drivers/slimbus/Kconfig                           |  11 +
>>   drivers/slimbus/Makefile                          |   5 +
>>   drivers/slimbus/slim-core.c                       | 695 ++++++++++++++++++++++
>>   include/linux/mod_devicetable.h                   |  13 +
>>   include/linux/slimbus.h                           | 299 ++++++++++
>>   9 files changed, 1192 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/slimbus/bus.txt
>>   create mode 100644 Documentation/slimbus/summary
>>   create mode 100644 drivers/slimbus/Kconfig
>>   create mode 100644 drivers/slimbus/Makefile
>>   create mode 100644 drivers/slimbus/slim-core.c
>>   create mode 100644 include/linux/slimbus.h
>>
>> diff --git a/Documentation/devicetree/bindings/slimbus/bus.txt b/Documentation/devicetree/bindings/slimbus/bus.txt
>> new file mode 100644
>> index 0000000..cb658bb
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/slimbus/bus.txt
>> @@ -0,0 +1,57 @@
>> +SLIM(Serial Low Power Interchip Media Bus) bus
>> +
>> +SLIMbus is a 2-wire bus, and is used to communicate with peripheral
>> +components like audio-codec.
>> +
>> +Controller is a normal device using binding for whatever bus it is
>> +on (e.g. platform bus).
>> +Required property for SLIMbus controller node:
>> +- compatible	- name of SLIMbus controller following generic names
>> +		recommended practice.
>> +- #address-cells - should be 2
>> +- #size-cells	- should be 0
>> +
>> +No other properties are required in the SLIMbus controller bus node.
>> +
>> +Child nodes:
>> +Every SLIMbus controller node can contain zero or more child nodes
>> +representing slave devices on the bus. Every SLIMbus slave device is
>> +uniquely determined by the enumeration address containing 4 fields:
>> +Manufacturer ID, Product code, Device index, and Instance value for
>> +the device.
>> +If child node is not present and it is instantiated after device
>> +discovery (slave device reporting itself present).
>> +
>> +In some cases it may be necessary to describe non-probeable device
>> +details such as non-standard ways of powering up a device. In
>> +such cases, child nodes for those devices will be present as
>> +slaves of the slimbus-controller, as detailed below.
>> +
>> +Required property for SLIMbus child node if it is present:
>> +- reg		- Is Duplex (Device index, Instance ID) from Enumeration
>> +		  Address.
>> +		  Device Index Uniquely identifies multiple Devices within
>> +		  a single Component.
>> +		  Instance ID Is for the cases where multiple Devices of the
>> +		  same type or Class are attached to the bus.
>> +
>> +- compatible	-"slimMID,PID". The textual representation of Manufacturer ID,
>> +	 	  Product Code, shall be in lower case hexadecimal with leading
>> +		  zeroes suppressed
> 
> This does sort of make sense but kinda makes the code a bit ugly
> parsing the MID and PID. Some parts will support SLIMBus and also
> other control interfaces, which means they would need to add an
> additional compatible string just for SLIMBus. It also breaks
> the normal conventions of vendor,part and finally it makes the
> compatible strings really unreadable which will be a bit annoying
> when looking at DTs.
> 
This change was made inline to the comments provided in previous version 
of the patch https://lkml.org/lkml/2016/5/3/576

> I think the MID and PID should just be included in the reg field
> and just leave this as a standard compatible.

AFAIK, reg field should only contain index and instance, which was also 
discussed  at https://lkml.org/lkml/2016/5/3/747

> 
>> +/**
> 
> This doesn't appear to be a kernel doc comment, so only /*.

Yep, I got similar comments from other reviewers too, so I will fix all 
such instances in next version.

> 
>> + * Report callbacks(device_up, device_down) are implemented by slimbus-devices.
>> + * The calls are scheduled into a workqueue to avoid holding up controller
>> + * initialization/tear-down.
>> + */
>> +static void schedule_slim_report(struct slim_controller *ctrl,
>> +				 struct slim_device *sb, bool report)
>> +{
>> +	struct sb_report_wd *sbw;
>> +
>> +	dev_dbg(&ctrl->dev, "report:%d for slave:%s\n", report, sb->name);
>> +
>> +	sbw = kmalloc(sizeof(*sbw), GFP_KERNEL);
>> +	if (!sbw)
>> +		return;
>> +
>> +	INIT_WORK(&sbw->wd, slim_report);
>> +	sbw->sbdev = sb;
>> +	sbw->report = report;
>> +	if (!queue_work(ctrl->wq, &sbw->wd)) {
>> +		dev_err(&ctrl->dev, "failed to queue report:%d slave:%s\n",
>> +				    report, sb->name);
>> +		kfree(sbw);
>> +	}
>> +}
>> +
>> +/**
>> + * slim_driver_register: Client driver registration with slimbus
> 
> A - after the function name usually works better, I think
> kernel-doc doesn't support a colon after the function name.

Will fix this in next version too.

> 
>> + * @drv:Client driver to be associated with client-device.
>> + * @owner: owning module/driver
>> + * This API will register the client driver with the slimbus
>> + * It is called from the driver's module-init function.
> 
> If you don't put a blank line after the arguments kernel doc will
> treat this as a run on for the description of owner rather than
> the long description for the function you intended it to be.

okay, I will fix such instances in the patchset in next version.

> 
>> +
>> +/* Helper to get hex Manufacturer ID and Product id from compatible */
>> +static unsigned long str2hex(unsigned char *str)
>> +{
>> +	int value = 0;
>> +
>> +	while (*str) {
>> +		char c = *str++;
>> +
>> +		value = value << 4;
>> +		if (c >= '0' && c <= '9')
>> +			value |= (c - '0');
>> +		if (c >= 'a' && c <= 'f')
>> +			value |= (c - 'a' + 10);
>> +
>> +	}
>> +
>> +	return value;
>> +}
> 
> Isn't this just reimplementing kstrtoul?
> 
I would say partly, I think kstrtoul will only parse string as hex if 
its prefixed with "0x" But the compatible does not have 0x prefix..
we could probably do some prefixing before passing to kstrtoul to remove 
above function.. I will try that and see!

>> +
>> +/* OF helpers for SLIMbus */
>> +static void of_register_slim_devices(struct slim_controller *ctrl)
>> +{
>> +	struct device *dev = &ctrl->dev;
>> +	struct device_node *node;
>> +
>> +	if (!ctrl->dev.of_node)
>> +		return;
>> +
>> +	for_each_child_of_node(ctrl->dev.of_node, node) {
>> +		struct slim_device *slim;
>> +		const char *compat = NULL;
>> +		char *p, *tok;
>> +		int reg[2], ret;
>> +
>> +		slim = kzalloc(sizeof(*slim), GFP_KERNEL);
>> +		if (!slim)
>> +			continue;
>> +
>> +		slim->dev.of_node = of_node_get(node);
>> +
>> +		compat = of_get_property(node, "compatible", NULL);
>> +		if (!compat)
>> +			continue;
>> +
>> +		p = kasprintf(GFP_KERNEL, "%s", compat + strlen("slim"));
>> +
>> +		tok = strsep(&p, ",");
>> +		if (!tok) {
>> +			dev_err(dev, "No valid Manufacturer ID found\n");
>> +			kfree(p);
>> +			continue;
>> +		}
>> +		slim->e_addr.manf_id = str2hex(tok);
>> +
>> +		tok = strsep(&p, ",");
>> +		if (!tok) {
>> +			dev_err(dev, "No valid Product ID found\n");
>> +			kfree(p);
>> +			continue;
>> +		}
>> +		slim->e_addr.prod_code = str2hex(tok);
>> +		kfree(p);
>> +
>> +		ret = of_property_read_u32_array(node, "reg", reg, 2);
>> +		if (ret) {
>> +			dev_err(dev, "Device and Instance id not found:%d\n",
>> +				ret);
>> +			continue;
>> +		}
>> +		slim->e_addr.dev_index = reg[0];
>> +		slim->e_addr.instance = reg[1];
> 
> As I said above, this feels a bit complex compared to just
> reading the e_addr from reg.

I agree, but as I said, its done as part of the review comments on v5 
patchset.
https://lkml.org/lkml/2016/5/3/747

> 
>> +
>> +		ret = slim_add_device(ctrl, slim);
>> +		if (ret)
>> +			dev_err(dev, "of_slim device register err:%d\n", ret);
>> +	}
>> +}
> 
>> +
>> +static int slim_boot_child(struct device *dev, void *unused)
>> +{
>> +	struct slim_driver *sbdrv;
>> +	struct slim_device *sbdev = to_slim_device(dev);
>> +
>> +	if (sbdev && sbdev->dev.driver) {
>> +		sbdrv = to_slim_driver(sbdev->dev.driver);
>> +		if (sbdrv->boot_device)
>> +			sbdrv->boot_device(sbdev);
>> +	}
>> +	return 0;
>> +}
>> +
>> +static int slim_match_dev(struct device *dev, void *data)
>> +{
>> +	struct slim_eaddr *e_addr = data;
>> +	struct slim_device *slim = to_slim_device(dev);
>> +
>> +	return slim_eaddr_equal(&slim->e_addr, e_addr);
>> +}
> 
> Would it make sense to move this down to above slim_query_device,
> that way all the related code is next to itself?
> slim_boot_child/slim_framer_booted and
> slim_match_dev/slim_query_device.
> 
Okay, Will give that a go.
>> +
>> +/**
>> + * slim_framer_booted: This function is called by controller after the active
>> + * framer has booted (using Bus Reset sequence, or after it has shutdown and has
>> + * come back up).
>> + * @ctrl: Controller associated with this framer
>> + * Components, devices on the bus may be in undefined state,
>> + * and this function triggers their drivers to do the needful
>> + * to bring them back in Reset state so that they can acquire sync, report
>> + * present and be operational again.
>> + */
>> +void slim_framer_booted(struct slim_controller *ctrl)
>> +{
>> +	if (!ctrl)
>> +		return;
>> +
>> +	device_for_each_child(&ctrl->dev, NULL, slim_boot_child);
>> +}
>> +EXPORT_SYMBOL_GPL(slim_framer_booted);
>> +
>> +/**
>> + * slim_query_device: Query and get handle to a device.
>> + * @ctrl: Controller on which this device will be added/queried
>> + * @e_addr: Enumeration address of the device to be queried
>> + * Returns pointer to a device if it has already reported. Creates a new
>> + * device and returns pointer to it if the device has not yet enumerated.
>> + */
>> +struct slim_device *slim_query_device(struct slim_controller *ctrl,
>> +				      struct slim_eaddr *e_addr)
>> +{
>> +	struct device *dev;
>> +	struct slim_device *slim = NULL;
>> +
>> +	dev = device_find_child(&ctrl->dev, e_addr, slim_match_dev);
>> +	if (dev) {
>> +		slim = to_slim_device(dev);
>> +		return slim;
>> +	}
>> +
>> +	slim = kzalloc(sizeof(struct slim_device), GFP_KERNEL);
>> +	if (IS_ERR(slim))
>> +		return NULL;
>> +
>> +	slim->e_addr = *e_addr;
>> +	if (slim_add_device(ctrl, slim) != 0) {
>> +		kfree(slim);
>> +		return NULL;
>> +	}
>> +	return slim;
>> +}
>> +EXPORT_SYMBOL_GPL(slim_query_device);
>> +
>> +static int ctrl_getaddr_entry(struct slim_controller *ctrl,
>> +			      struct slim_eaddr *eaddr, u8 *entry)
>> +{
>> +	int i;
>> +
>> +	for (i = 0; i < ctrl->num_dev; i++) {
>> +		if (ctrl->addrt[i].valid &&
>> +		    slim_eaddr_equal(&ctrl->addrt[i].eaddr, eaddr)) {
>> +			*entry = i;
>> +			return 0;
>> +		}
>> +	}
>> +	return -ENXIO;
>> +}
>> +
>> +/**
>> + * slim_assign_laddr: Assign logical address to a device enumerated.
>> + * @ctrl: Controller with which device is enumerated.
>> + * @e_addr: Enumeration address of the device.
>> + * @laddr: Return logical address (if valid flag is false)
>> + * @valid: true if laddr holds a valid address that controller wants to
>> + *	set for this enumeration address. Otherwise framework sets index into
>> + *	address table as logical address.
>> + * Called by controller in response to REPORT_PRESENT. Framework will assign
>> + * a logical address to this enumeration address.
>> + * Function returns -EXFULL to indicate that all logical addresses are already
>> + * taken.
>> + */
>> +int slim_assign_laddr(struct slim_controller *ctrl, struct slim_eaddr *e_addr,
>> +		      u8 *laddr, bool valid)
> 
> I would be inclined to remove the valid parameter and just
> use get_laddr in here.  Feels weird to have two mechanisms
> for specify the laddr and presumably if the controller wants
> to specify the laddr it will need to support get_laddr.
> Additionally, I would make get_laddr optional which feels more
> sensible, indeed the code appears otherwise implements with that
> assumption.
Yep makes sense, I will give it a go in next version.

> 
>> +{
>> +	int ret;
>> +	u8 i = 0;
>> +	bool exists = false;
>> +	struct slim_device *slim;
>> +	struct slim_addrt *temp;
>> +
>> +	mutex_lock(&ctrl->m_ctrl);
>> +	/* already assigned */
>> +	if (ctrl_getaddr_entry(ctrl, e_addr, &i) == 0) {
>> +		*laddr = ctrl->addrt[i].laddr;
>> +		exists = true;
>> +	} else {
>> +		if (ctrl->num_dev >= (SLIM_LA_MANAGER - 1)) {
>> +			ret = -EXFULL;
>> +			goto ret_assigned_laddr;
>> +		}
>> +		for (i = 0; i < ctrl->num_dev; i++) {
>> +			if (ctrl->addrt[i].valid == false)
>> +				break;
>> +		}
>> +		if (i == ctrl->num_dev) {
>> +			temp = krealloc(ctrl->addrt,
>> +					(ctrl->num_dev + 1) *
>> +					sizeof(struct slim_addrt),
>> +					GFP_KERNEL);
>> +			if (!temp) {
>> +				ret = -ENOMEM;
>> +				goto ret_assigned_laddr;
>> +			}
>> +			ctrl->addrt = temp;
>> +			ctrl->num_dev++;
>> +		}
>> +		ctrl->addrt[i].eaddr = *e_addr;
>> +		ctrl->addrt[i].valid = true;
>> +
>> +		/* Preferred address is index into table */
>> +		if (!valid)
>> +			*laddr = i;
>> +	}
>> +
>> +	ret = ctrl->set_laddr(ctrl, &ctrl->addrt[i].eaddr, *laddr);
>> +	if (ret) {
>> +		ctrl->addrt[i].valid = false;
>> +		goto ret_assigned_laddr;
>> +	}
>> +	ctrl->addrt[i].laddr = *laddr;
>> +
>> +ret_assigned_laddr:
>> +	mutex_unlock(&ctrl->m_ctrl);
>> +	if (exists || ret)
>> +		return ret;
>> +
>> +	dev_info(&ctrl->dev, "setting slimbus l-addr:%x, ea:%x,%x,%x,%x\n",
>> +		*laddr, e_addr->manf_id, e_addr->prod_code,
>> +		e_addr->dev_index, e_addr->instance);
>> +
>> +	/**
>> +	 * Add this device to list of devices on this controller if it's
>> +	 * not already present
>> +	 */
>> +	slim = slim_query_device(ctrl, e_addr);
>> +	if (!slim) {
>> +		ret = -ENODEV;
>> +	} else {
>> +		struct slim_driver *sbdrv;
>> +
>> +		slim->laddr = *laddr;
>> +		mutex_lock(&slim->report_lock);
>> +		slim->reported = true;
>> +		if (slim->dev.driver) {
>> +			sbdrv = to_slim_driver(slim->dev.driver);
>> +			if (sbdrv->device_up)
>> +				schedule_slim_report(ctrl, slim, true);
>> +		}
>> +		mutex_unlock(&slim->report_lock);
>> +	}
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(slim_assign_laddr);
>> +
>> +/**
>> + * slim_get_logical_addr: Return the logical address of a slimbus device.
>> + * @sb: client handle requesting the address.
>> + * @e_addr: Enumeration address of the device.
>> + * @laddr: output buffer to store the address
>> + * context: can sleep
>> + * -EINVAL is returned in case of invalid parameters, and -ENXIO is returned if
>> + *  the device with this enumeration address is not found.
>> + */
>> +int slim_get_logical_addr(struct slim_device *sb, struct slim_eaddr *e_addr,
>> +			  u8 *laddr)
>> +{
>> +	int ret;
>> +	u8 entry;
>> +	struct slim_controller *ctrl = sb->ctrl;
>> +
>> +	if (!ctrl || !laddr || !e_addr)
>> +		return -EINVAL;
>> +
>> +	mutex_lock(&ctrl->m_ctrl);
>> +	ret = ctrl_getaddr_entry(ctrl, e_addr, &entry);
>> +	if (!ret)
>> +		*laddr = ctrl->addrt[entry].laddr;
>> +	mutex_unlock(&ctrl->m_ctrl);
>> +
>> +	if (ret == -ENXIO && ctrl->get_laddr) {
>> +		ret = ctrl->get_laddr(ctrl, e_addr, laddr);
>> +		if (!ret)
>> +			ret = slim_assign_laddr(ctrl, e_addr, laddr, true);
>> +	}
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(slim_get_logical_addr);
> 
> I find the interface across these two functions
> (assign_laddr/get_logical_addr) a little odd. Since
> get_logical_addr calls assign_laddr if it couldn't find the
> laddr and then assign_laddr actually does another search for the
> laddr. Would it perhaps make sense to combine these into one
> function?
Yes these two functions can be combined, Will fix this in next version.
> 
> Thanks,
> Charles
> 
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Thanks for your review comments,

On 10/10/17 11:45, Vinod Koul wrote:
> On Fri, Oct 06, 2017 at 05:51:30PM +0200, srinivas.kandagatla@linaro.org wrote:
>> From: Sagar Dharia <sdharia@codeaurora.org>
>>
>> SLIMbus (Serial Low Power Interchip Media Bus) is a specification
>> developed by MIPI (Mobile Industry Processor Interface) alliance.
>> SLIMbus is a 2-wire implementation, which is used to communicate with
>> peripheral components like audio-codec.
>> SLIMbus uses Time-Division-Multiplexing to accommodate multiple data
>> channels, and control channel. Control channel has messages to do
>> device-enumeration, messages to send/receive control-data to/from
>> slimbus devices, messages for port/channel management, and messages to
>> do bandwidth allocation.
>> The framework supports multiple instances of the bus (1 controller per
>> bus), and multiple slave devices per controller.
>>
>> This patch does device enumeration, logical address assignment,
>> informing device when the device reports present/absent etc.
>> Reporting present may need the driver to do the needful (e.g. turning
>> on voltage regulators powering the device). Additionally device is
>> probed when it reports present if that device doesn't need any such
>> steps mentioned above.
>>
>> Signed-off-by: Sagar Dharia <sdharia@codeaurora.org>
>> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
>> ---
>>   Documentation/devicetree/bindings/slimbus/bus.txt |  57 ++
>>   Documentation/slimbus/summary                     | 109 ++++
>>   drivers/Kconfig                                   |   2 +
>>   drivers/Makefile                                  |   1 +
>>   drivers/slimbus/Kconfig                           |  11 +
>>   drivers/slimbus/Makefile                          |   5 +
>>   drivers/slimbus/slim-core.c                       | 695 ++++++++++++++++++++++
>>   include/linux/mod_devicetable.h                   |  13 +
>>   include/linux/slimbus.h                           | 299 ++++++++++
>>   9 files changed, 1192 insertions(+)
> 
> thats a lot of code for review, consider splitting it up further for better
> reviews

Its was suggested that parts of dtbindings and of_* wrapper merged into 
this patch.  In V5 review comments. https://lkml.org/lkml/2016/4/28/175


> 
>>   create mode 100644 Documentation/devicetree/bindings/slimbus/bus.txt
>>   create mode 100644 Documentation/slimbus/summary
>>   create mode 100644 drivers/slimbus/Kconfig
>>   create mode 100644 drivers/slimbus/Makefile
>>   create mode 100644 drivers/slimbus/slim-core.c
> 
> how about core.c (https://lkml.org/lkml/2017/7/12/430)
> 
Makes sense, will do that in next version.

>> +static const struct slim_device_id *slim_match(const struct slim_device_id *id,
>> +					       const struct slim_device *sbdev)
>> +{
>> +	while (id->manf_id != 0 || id->prod_code != 0) {
>> +		if (id->manf_id == sbdev->e_addr.manf_id &&
>> +		    id->prod_code == sbdev->e_addr.prod_code &&
>> +		    id->dev_index == sbdev->e_addr.dev_index)
>> +			return id;
>> +		id++;
>> +	}
>> +	return NULL;
>> +}
>> +
>> +static int slim_device_match(struct device *dev, struct device_driver *drv)
>> +{
>> +	struct slim_device *sbdev = to_slim_device(dev);
>> +	struct slim_driver *sbdrv = to_slim_driver(drv);
>> +
>> +	/* Attempt an OF style match first */
>> +	if (of_driver_match_device(dev, drv))
>> +		return 1;
> 
> is of_driver_match_device() a must have here? (I dont completely understand
Yes, we need this to match the compatible string from device tree vs 
driver itself, most of the bus driver do this in bus match functions.


> DT so pardon my ignorance). Since we have devices with ids can we use that
> alone for matching?

Two cases to consider here,
1> If the device is up and discoverable.
2> Device is not discoverable yet, as it needs some power up sequence.


In first case comparing with ID table makes sense.

But second case we would want to probe the device(for power sequencing) 
before we can discover the device on bus.


This code as it is supports both DT and id_table.

>> +
>> +	/* Then try to match against the id table */
>> +	if (sbdrv->id_table)
>> +		return slim_match(sbdrv->id_table, sbdev) != NULL;
>> +
>> +	return 0;
>> +}
>> +
> 
> rather than jumping now to reporting APIs, can we club all bus_type parts to
> one place (patch) so that it is easier to review logically
> 
Let me try that in next version.

>> +struct sb_report_wd {
>> +	struct work_struct wd;
>> +	struct slim_device *sbdev;
>> +	bool report;
>> +};
>> +
>> +static void slim_report(struct work_struct *work)
>> +{
>> +	struct slim_driver *sbdrv;
>> +	struct sb_report_wd *sbw = container_of(work, struct sb_report_wd, wd);
>> +	struct slim_device *sbdev = sbw->sbdev;
>> +
>> +	mutex_lock(&sbdev->report_lock);
>> +	if (!sbdev->dev.driver)
>> +		goto report_exit;
>> +
>> +	/* check if device-up or down needs to be called */
>> +	if ((!sbdev->reported && !sbdev->notified) ||
>> +	    (sbdev->reported && sbdev->notified))
>> +		goto report_exit;
>> +
>> +	sbdrv = to_slim_driver(sbdev->dev.driver);
>> +
>> +	/**
>> +	 * address no longer valid, means device reported absent, whereas
>> +	 * address valid, means device reported present
>> +	 */
> 
> I think ppl commented about this style, so lets fix those issues
> 

sure.

>> +	if (sbdev->notified && !sbdev->reported) {
>> +		sbdev->notified = false;
>> +		if (sbdrv->device_down)
>> +			sbdrv->device_down(sbdev);
>> +	} else if (!sbdev->notified && sbdev->reported) {
>> +		sbdev->notified = true;
>> +		if (sbdrv->device_up)
>> +			sbdrv->device_up(sbdev);
> 
> what do the device_up/down calls signify here?
> 
up would be called when a device is discovered on the bus, and down on 
when the device disappeared on slimbus.

>> +static int slim_device_probe(struct device *dev)
>> +{
>> +	struct slim_device	*sbdev;
>> +	struct slim_driver	*sbdrv;
>> +	int status = 0;
>> +
>> +	sbdev = to_slim_device(dev);
>> +	sbdrv = to_slim_driver(dev->driver);
>> +
>> +	sbdev->driver = sbdrv;
>> +
>> +	if (sbdrv->probe)
>> +		status = sbdrv->probe(sbdev);
>> +
>> +	if (status)
>> +		sbdev->driver = NULL;
>> +	else if (sbdrv->device_up)
>> +		schedule_slim_report(sbdev->ctrl, sbdev, true);
> 
> can you please explain what this is trying to do?

It is scheduling a device_up() callback in workqueue for reporting 
discovered device.


> 
>> +int __slim_driver_register(struct slim_driver *drv, struct module *owner)
>> +{
>> +	drv->driver.bus = &slimbus_type;
>> +	drv->driver.owner = owner;
>> +	return driver_register(&drv->driver);
>> +}
>> +EXPORT_SYMBOL_GPL(__slim_driver_register);
> 
> any reason to use __ for this API?

This is made inline with __platfrom_driver_register() suggested in v5 
review.

> 
>> +static int slim_add_device(struct slim_controller *ctrl,
>> +			   struct slim_device *sbdev)
>> +{
>> +	sbdev->dev.bus = &slimbus_type;
>> +	sbdev->dev.parent = &ctrl->dev;
>> +	sbdev->dev.release = slim_dev_release;
>> +	sbdev->dev.driver = NULL;
>> +	sbdev->ctrl = ctrl;
>> +
>> +	slim_ctrl_get(ctrl);
>> +	sbdev->name = kasprintf(GFP_KERNEL, "%x:%x:%x:%x",
>> +					sbdev->e_addr.manf_id,
>> +					sbdev->e_addr.prod_code,
>> +					sbdev->e_addr.dev_index,
>> +					sbdev->e_addr.instance);
>> +	if (!sbdev->name)
>> +		return -ENOMEM;
>> +
>> +	dev_set_name(&sbdev->dev, "%s", sbdev->name);
>> +	mutex_init(&sbdev->report_lock);
>> +
>> +	/* probe slave on this controller */
>> +	return device_register(&sbdev->dev);
> 
> I dont think the comment is quite correct, you register a device not probe!
> 
Will fix this in next version.

>> +/* OF helpers for SLIMbus */
>> +static void of_register_slim_devices(struct slim_controller *ctrl)
>> +{
>> +	struct device *dev = &ctrl->dev;
>> +	struct device_node *node;
>> +
>> +	if (!ctrl->dev.of_node)
>> +		return;
>> +
>> +	for_each_child_of_node(ctrl->dev.of_node, node) {
>> +		struct slim_device *slim;
>> +		const char *compat = NULL;
>> +		char *p, *tok;
>> +		int reg[2], ret;
>> +
>> +		slim = kzalloc(sizeof(*slim), GFP_KERNEL);
>> +		if (!slim)
>> +			continue;
>> +
>> +		slim->dev.of_node = of_node_get(node);
>> +
>> +		compat = of_get_property(node, "compatible", NULL);
>> +		if (!compat)
>> +			continue;
>> +
>> +		p = kasprintf(GFP_KERNEL, "%s", compat + strlen("slim"));
>> +
>> +		tok = strsep(&p, ",");
>> +		if (!tok) {
>> +			dev_err(dev, "No valid Manufacturer ID found\n");
>> +			kfree(p);
>> +			continue;
>> +		}
>> +		slim->e_addr.manf_id = str2hex(tok);
>> +
>> +		tok = strsep(&p, ",");
>> +		if (!tok) {
>> +			dev_err(dev, "No valid Product ID found\n");
>> +			kfree(p);
>> +			continue;
>> +		}
>> +		slim->e_addr.prod_code = str2hex(tok);
>> +		kfree(p);
>> +
>> +		ret = of_property_read_u32_array(node, "reg", reg, 2);
>> +		if (ret) {
>> +			dev_err(dev, "Device and Instance id not found:%d\n",
>> +				ret);
>> +			continue;
>> +		}
>> +		slim->e_addr.dev_index = reg[0];
>> +		slim->e_addr.instance = reg[1];
>> +
>> +		ret = slim_add_device(ctrl, slim);
> 
> okay this is good stuff. So we scan the DT for slimbus devices and register
> them here. Same stuff we can do with ACPI :)
> 
> then why do we need the of register stuff I commented earlier. A Slimbus
> device can work irrespective of firmware type and registers using various
> ids. The platform will scan firmware (dt/acpi) create devices and load
> drivers against them generically.  Apart from this code we ideally should
> not have any DT parts in the bus, do you agree?

I partly agree with you, as all the devices on slimbus might not be in a 
discoverable state. Such devices would need some sort of power up 
sequence which what the of_wrapper and the match function are trying to 
achieve. Driver probe will be called based on the compatible match which 
would then power up/reset the device so that it can announce itself and 
the device_up() would be called at that point.

Your comment is 100% true, If the devices are in discoverable state, in 
such case we would not need any DT entires as you said.

> 
>> +		if (ret)
>> +			dev_err(dev, "of_slim device register err:%d\n", ret);
>> +	}
>> +}
>> +
>> +/**
>> + * slim_register_controller: Controller bring-up and registration.
>> + * @ctrl: Controller to be registered.
>> + * A controller is registered with the framework using this API.
>> + * If devices on a controller were registered before controller,
>> + * this will make sure that they get probed when controller is up
>> + */
>> +int slim_register_controller(struct slim_controller *ctrl)
>> +{
>> +	int id, ret = 0;
>> +
>> +	mutex_lock(&slim_lock);
>> +	id = idr_alloc(&ctrl_idr, ctrl, ctrl->nr, -1, GFP_KERNEL);
> 
> what are these ids used for?

I think these are the controller ids, just to create a proper name space 
for each controller.

> 
>> +	mutex_unlock(&slim_lock);
>> +
>> +	if (id < 0)
>> +		return id;
>> +
>> +	ctrl->nr = id;
>> +
>> +	dev_set_name(&ctrl->dev, "sb-%d", ctrl->nr);
>> +	ctrl->num_dev = 0;
>> +
>> +	if (!ctrl->min_cg)
>> +		ctrl->min_cg = SLIM_MIN_CLK_GEAR;
>> +	if (!ctrl->max_cg)
>> +		ctrl->max_cg = SLIM_MAX_CLK_GEAR;
>> +
>> +	mutex_init(&ctrl->m_ctrl);
>> +	ret = device_register(&ctrl->dev);
> 
> one more device_register?? Can you explain why
> 

This is a device for each controller.

>> +/**
>> + * struct slim_addrt: slimbus address used internally by the slimbus framework.
>> + * @valid: If the device is present. Valid is set to false when device reports
>> + *	absent.
>> + * @eaddr: Enumeration address
>> + * @laddr: It is possible that controller will set a predefined logical address
>> + *	rather than the one assigned by framework. (i.e. logical address may
>> + *	not be same as index into this table). This entry will store the
>> + *	logical address value for this enumeration address.
>> + */
>> +struct slim_addrt {
> 
> addrt? why not just addr?
yes, it can be done! will fix this in next version.
> 
>> +	bool			valid;
>> +	struct slim_eaddr	eaddr;
>> +	u8			laddr;
>> +};
>> +
>> +/* SLIMbus message types. Related to interpretation of message code. */
>> +#define SLIM_MSG_MT_CORE			0x0
>> +#define SLIM_MSG_MT_DEST_REFERRED_CLASS		0x1
>> +#define SLIM_MSG_MT_DEST_REFERRED_USER		0x2
>> +#define SLIM_MSG_MT_SRC_REFERRED_CLASS		0x5
>> +#define SLIM_MSG_MT_SRC_REFERRED_USER		0x6
> 
> BIT() GENMASK() please here and other places where they define bits in spec
> 
>> +/**
>> + * struct slim_driver: Slimbus 'generic device' (slave) device driver
>> + *				(similar to 'spi_device' on SPI)
>> + * @probe: Binds this driver to a slimbus device.
>> + * @remove: Unbinds this driver from the slimbus device.
>> + * @shutdown: Standard shutdown callback used during powerdown/halt.
>> + * @suspend: Standard suspend callback used during system suspend
>> + * @resume: Standard resume callback used during system resume
>> + * @device_up: This callback is called when the device reports present and
>> + *		gets a logical address assigned to it
>> + * @device_down: This callback is called when device reports absent, or the
>> + *		bus goes down. Device will report present when bus is up and
>> + *		device_up callback will be called again when that happens
> 
> do we need two callback, why not a status or notify callback with argument
> for up/down?

I will give it a try and see how it looks!

> 
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On Tue, Oct 10, 2017 at 01:34:48PM +0100, Srinivas Kandagatla wrote:
> Thanks for the review comments.
> 
> On 10/10/17 11:05, Charles Keepax wrote:
> > On Fri, Oct 06, 2017 at 05:51:30PM +0200, srinivas.kandagatla@linaro.org wrote:
> > > +Required property for SLIMbus child node if it is present:
> > > +- reg		- Is Duplex (Device index, Instance ID) from Enumeration
> > > +		  Address.
> > > +		  Device Index Uniquely identifies multiple Devices within
> > > +		  a single Component.
> > > +		  Instance ID Is for the cases where multiple Devices of the
> > > +		  same type or Class are attached to the bus.
> > > +
> > > +- compatible	-"slimMID,PID". The textual representation of Manufacturer ID,
> > > +	 	  Product Code, shall be in lower case hexadecimal with leading
> > > +		  zeroes suppressed
> > 
> > This does sort of make sense but kinda makes the code a bit ugly
> > parsing the MID and PID. Some parts will support SLIMBus and also
> > other control interfaces, which means they would need to add an
> > additional compatible string just for SLIMBus. It also breaks
> > the normal conventions of vendor,part and finally it makes the
> > compatible strings really unreadable which will be a bit annoying
> > when looking at DTs.
> > 
> This change was made inline to the comments provided in previous version of
> the patch https://lkml.org/lkml/2016/5/3/576
> 
> > I think the MID and PID should just be included in the reg field
> > and just leave this as a standard compatible.
> 
> AFAIK, reg field should only contain index and instance, which was also
> discussed  at https://lkml.org/lkml/2016/5/3/747
> 

Thanks for the links, if people are determined this is the way
to go I can live with it. I guess my primary objection is the
fact my parts are going to have different compatibles depending
on if they are on I2C/SPI or on SLIMBus (we have many parts that
support all three on the same chip) which feels like it violates
the principle of least surprise. Will wait to see if Arnd or Rob
have anymore thoughts to offer.

> > > +/* Helper to get hex Manufacturer ID and Product id from compatible */
> > > +static unsigned long str2hex(unsigned char *str)
> > > +{
> > > +	int value = 0;
> > > +
> > > +	while (*str) {
> > > +		char c = *str++;
> > > +
> > > +		value = value << 4;
> > > +		if (c >= '0' && c <= '9')
> > > +			value |= (c - '0');
> > > +		if (c >= 'a' && c <= 'f')
> > > +			value |= (c - 'a' + 10);
> > > +
> > > +	}
> > > +
> > > +	return value;
> > > +}
> > 
> > Isn't this just reimplementing kstrtoul?
> > 
> I would say partly, I think kstrtoul will only parse string as hex if its
> prefixed with "0x" But the compatible does not have 0x prefix..
> we could probably do some prefixing before passing to kstrtoul to remove
> above function.. I will try that and see!
> 

I am pretty sure kstrtoul is happy without the 0x as long as you
specify the base as 16 which I guess you should be doing here.

Thanks,
Charles
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On Tue, Oct 10, 2017 at 01:34:55PM +0100, Srinivas Kandagatla wrote:
> >>  9 files changed, 1192 insertions(+)
> >
> >thats a lot of code for review, consider splitting it up further for better
> >reviews
> 
> Its was suggested that parts of dtbindings and of_* wrapper merged into this
> patch.  In V5 review comments. https://lkml.org/lkml/2016/4/28/175

yes but it can still be split :)


> >>+static const struct slim_device_id *slim_match(const struct slim_device_id *id,
> >>+					       const struct slim_device *sbdev)
> >>+{
> >>+	while (id->manf_id != 0 || id->prod_code != 0) {
> >>+		if (id->manf_id == sbdev->e_addr.manf_id &&
> >>+		    id->prod_code == sbdev->e_addr.prod_code &&
> >>+		    id->dev_index == sbdev->e_addr.dev_index)
> >>+			return id;
> >>+		id++;
> >>+	}
> >>+	return NULL;
> >>+}
> >>+
> >>+static int slim_device_match(struct device *dev, struct device_driver *drv)
> >>+{
> >>+	struct slim_device *sbdev = to_slim_device(dev);
> >>+	struct slim_driver *sbdrv = to_slim_driver(drv);
> >>+
> >>+	/* Attempt an OF style match first */
> >>+	if (of_driver_match_device(dev, drv))
> >>+		return 1;
> >
> >is of_driver_match_device() a must have here? (I dont completely understand
> Yes, we need this to match the compatible string from device tree vs driver
> itself, most of the bus driver do this in bus match functions.
> 
> 
> >DT so pardon my ignorance). Since we have devices with ids can we use that
> >alone for matching?
> 
> Two cases to consider here,
> 1> If the device is up and discoverable.
> 2> Device is not discoverable yet, as it needs some power up sequence.
> 
> 
> In first case comparing with ID table makes sense.
> 
> But second case we would want to probe the device(for power sequencing)
> before we can discover the device on bus.
> 
> 
> This code as it is supports both DT and id_table.

Why not only id_table, see below:

> >>+	if (sbdev->notified && !sbdev->reported) {
> >>+		sbdev->notified = false;
> >>+		if (sbdrv->device_down)
> >>+			sbdrv->device_down(sbdev);
> >>+	} else if (!sbdev->notified && sbdev->reported) {
> >>+		sbdev->notified = true;
> >>+		if (sbdrv->device_up)
> >>+			sbdrv->device_up(sbdev);
> >
> >what do the device_up/down calls signify here?
> >
> up would be called when a device is discovered on the bus, and down on when
> the device disappeared on slimbus.
> 
> >>+static int slim_device_probe(struct device *dev)
> >>+{
> >>+	struct slim_device	*sbdev;
> >>+	struct slim_driver	*sbdrv;
> >>+	int status = 0;
> >>+
> >>+	sbdev = to_slim_device(dev);
> >>+	sbdrv = to_slim_driver(dev->driver);
> >>+
> >>+	sbdev->driver = sbdrv;
> >>+
> >>+	if (sbdrv->probe)
> >>+		status = sbdrv->probe(sbdev);
> >>+
> >>+	if (status)
> >>+		sbdev->driver = NULL;
> >>+	else if (sbdrv->device_up)
> >>+		schedule_slim_report(sbdev->ctrl, sbdev, true);
> >
> >can you please explain what this is trying to do?
> 
> It is scheduling a device_up() callback in workqueue for reporting
> discovered device.

any reason for that? Would the device not announce itself on the bus and
then you can synchronously update the device.

> >>+int __slim_driver_register(struct slim_driver *drv, struct module *owner)
> >>+{
> >>+	drv->driver.bus = &slimbus_type;
> >>+	drv->driver.owner = owner;
> >>+	return driver_register(&drv->driver);
> >>+}
> >>+EXPORT_SYMBOL_GPL(__slim_driver_register);
> >
> >any reason to use __ for this API?
> 
> This is made inline with __platfrom_driver_register() suggested in v5
> review.

I guess Greg is best person to make this call :)

> >>+static void of_register_slim_devices(struct slim_controller *ctrl)
> >>+{
> >>+	struct device *dev = &ctrl->dev;
> >>+	struct device_node *node;
> >>+
> >>+	if (!ctrl->dev.of_node)
> >>+		return;
> >>+
> >>+	for_each_child_of_node(ctrl->dev.of_node, node) {
> >>+		struct slim_device *slim;
> >>+		const char *compat = NULL;
> >>+		char *p, *tok;
> >>+		int reg[2], ret;
> >>+
> >>+		slim = kzalloc(sizeof(*slim), GFP_KERNEL);
> >>+		if (!slim)
> >>+			continue;
> >>+
> >>+		slim->dev.of_node = of_node_get(node);
> >>+
> >>+		compat = of_get_property(node, "compatible", NULL);
> >>+		if (!compat)
> >>+			continue;
> >>+
> >>+		p = kasprintf(GFP_KERNEL, "%s", compat + strlen("slim"));
> >>+
> >>+		tok = strsep(&p, ",");
> >>+		if (!tok) {
> >>+			dev_err(dev, "No valid Manufacturer ID found\n");
> >>+			kfree(p);
> >>+			continue;
> >>+		}
> >>+		slim->e_addr.manf_id = str2hex(tok);
> >>+
> >>+		tok = strsep(&p, ",");
> >>+		if (!tok) {
> >>+			dev_err(dev, "No valid Product ID found\n");
> >>+			kfree(p);
> >>+			continue;
> >>+		}
> >>+		slim->e_addr.prod_code = str2hex(tok);
> >>+		kfree(p);
> >>+
> >>+		ret = of_property_read_u32_array(node, "reg", reg, 2);
> >>+		if (ret) {
> >>+			dev_err(dev, "Device and Instance id not found:%d\n",
> >>+				ret);
> >>+			continue;
> >>+		}
> >>+		slim->e_addr.dev_index = reg[0];
> >>+		slim->e_addr.instance = reg[1];
> >>+
> >>+		ret = slim_add_device(ctrl, slim);
> >
> >okay this is good stuff. So we scan the DT for slimbus devices and register
> >them here. Same stuff we can do with ACPI :)
> >
> >then why do we need the of register stuff I commented earlier. A Slimbus
> >device can work irrespective of firmware type and registers using various
> >ids. The platform will scan firmware (dt/acpi) create devices and load
> >drivers against them generically.  Apart from this code we ideally should
> >not have any DT parts in the bus, do you agree?
> 
> I partly agree with you, as all the devices on slimbus might not be in a
> discoverable state. Such devices would need some sort of power up sequence
> which what the of_wrapper and the match function are trying to achieve.
> Driver probe will be called based on the compatible match which would then
> power up/reset the device so that it can announce itself and the device_up()
> would be called at that point.
> 
> Your comment is 100% true, If the devices are in discoverable state, in such
> case we would not need any DT entires as you said.

Yes you are right. Since the device need to be powered up thru side band we
cannot live without using firmware (acpi/dt)

Now consider the below scheme:
 - The Bus scans device node of the controller (acpi/dt), as
   above and find the slim devices and adds them. The ID needs to be
   extracted from firmware (acpi/dt), we sure need to set the right firmware
   node for the device
 - Drivers register based on ID, no need to make it DT/ACPI aware
 - Match function is invoked and driver probed
 - Sideband mechanism kick in and power up device and it announces on the
   bus

In case it is already powered up, it can announce being up earlier.

FWIW i am using above method with ACPI on SoundWire.

> 
> >
> >>+		if (ret)
> >>+			dev_err(dev, "of_slim device register err:%d\n", ret);
> >>+	}
> >>+}
> >>+
> >>+/**
> >>+ * slim_register_controller: Controller bring-up and registration.
> >>+ * @ctrl: Controller to be registered.
> >>+ * A controller is registered with the framework using this API.
> >>+ * If devices on a controller were registered before controller,
> >>+ * this will make sure that they get probed when controller is up
> >>+ */
> >>+int slim_register_controller(struct slim_controller *ctrl)
> >>+{
> >>+	int id, ret = 0;
> >>+
> >>+	mutex_lock(&slim_lock);
> >>+	id = idr_alloc(&ctrl_idr, ctrl, ctrl->nr, -1, GFP_KERNEL);
> >
> >what are these ids used for?
> 
> I think these are the controller ids, just to create a proper name space for
> each controller.
> 
> >
> >>+	mutex_unlock(&slim_lock);
> >>+
> >>+	if (id < 0)
> >>+		return id;
> >>+
> >>+	ctrl->nr = id;
> >>+
> >>+	dev_set_name(&ctrl->dev, "sb-%d", ctrl->nr);
> >>+	ctrl->num_dev = 0;
> >>+
> >>+	if (!ctrl->min_cg)
> >>+		ctrl->min_cg = SLIM_MIN_CLK_GEAR;
> >>+	if (!ctrl->max_cg)
> >>+		ctrl->max_cg = SLIM_MAX_CLK_GEAR;
> >>+
> >>+	mutex_init(&ctrl->m_ctrl);
> >>+	ret = device_register(&ctrl->dev);
> >
> >one more device_register?? Can you explain why
> >
> 
> This is a device for each controller.

wont the controller have its own platform_device?

On 10/10/17 17:49, Vinod Koul wrote:
> On Tue, Oct 10, 2017 at 01:34:55PM +0100, Srinivas Kandagatla wrote:
>>>>   9 files changed, 1192 insertions(+)
>>>
>>> thats a lot of code for review, consider splitting it up further for better
>>> reviews
>>
>> Its was suggested that parts of dtbindings and of_* wrapper merged into this
>> patch.  In V5 review comments. https://lkml.org/lkml/2016/4/28/175
> 
> yes but it can still be split :)
> 
Will give it a go in next version!!
> 
>>>> +static const struct slim_device_id *slim_match(const struct slim_device_id *id,
>>>> +					       const struct slim_device *sbdev)
>>>> +{
>>>> +	while (id->manf_id != 0 || id->prod_code != 0) {
>>>> +		if (id->manf_id == sbdev->e_addr.manf_id &&
>>>> +		    id->prod_code == sbdev->e_addr.prod_code &&
>>>> +		    id->dev_index == sbdev->e_addr.dev_index)
>>>> +			return id;
>>>> +		id++;
>>>> +	}
>>>> +	return NULL;
>>>> +}
>>>> +
>>>> +static int slim_device_match(struct device *dev, struct device_driver *drv)
>>>> +{
>>>> +	struct slim_device *sbdev = to_slim_device(dev);
>>>> +	struct slim_driver *sbdrv = to_slim_driver(drv);
>>>> +
>>>> +	/* Attempt an OF style match first */
>>>> +	if (of_driver_match_device(dev, drv))
>>>> +		return 1;
>>>
>>> is of_driver_match_device() a must have here? (I dont completely understand
>> Yes, we need this to match the compatible string from device tree vs driver
>> itself, most of the bus driver do this in bus match functions.
>>
>>
>>> DT so pardon my ignorance). Since we have devices with ids can we use that
>>> alone for matching?
>>
>> Two cases to consider here,
>> 1> If the device is up and discoverable.
>> 2> Device is not discoverable yet, as it needs some power up sequence.
>>
>>
>> In first case comparing with ID table makes sense.
>>
>> But second case we would want to probe the device(for power sequencing)
>> before we can discover the device on bus.
>>
>>
>> This code as it is supports both DT and id_table.
> 
> Why not only id_table, see below:
> 


Yes, we make id_table as mandatory field for all slimbus drivers.


>>>> +	if (sbdev->notified && !sbdev->reported) {
>>>> +		sbdev->notified = false;
>>>> +		if (sbdrv->device_down)
>>>> +			sbdrv->device_down(sbdev);
>>>> +	} else if (!sbdev->notified && sbdev->reported) {
>>>> +		sbdev->notified = true;
>>>> +		if (sbdrv->device_up)
>>>> +			sbdrv->device_up(sbdev);
>>>
>>> what do the device_up/down calls signify here?
>>>
>> up would be called when a device is discovered on the bus, and down on when
>> the device disappeared on slimbus.
>>
>>>> +static int slim_device_probe(struct device *dev)
>>>> +{
>>>> +	struct slim_device	*sbdev;
>>>> +	struct slim_driver	*sbdrv;
>>>> +	int status = 0;
>>>> +
>>>> +	sbdev = to_slim_device(dev);
>>>> +	sbdrv = to_slim_driver(dev->driver);
>>>> +
>>>> +	sbdev->driver = sbdrv;
>>>> +
>>>> +	if (sbdrv->probe)
>>>> +		status = sbdrv->probe(sbdev);
>>>> +
>>>> +	if (status)
>>>> +		sbdev->driver = NULL;
>>>> +	else if (sbdrv->device_up)
>>>> +		schedule_slim_report(sbdev->ctrl, sbdev, true);
>>>
>>> can you please explain what this is trying to do?
>>
>> It is scheduling a device_up() callback in workqueue for reporting
>> discovered device.
> 
> any reason for that? Would the device not announce itself on the bus and
> then you can synchronously update the device.
You are correct,  Device should announce itself in all cases. core 
should only call this callback only when device is announced, it does 
not make sense for this call in slim_device_probe(). Will remove it from 
here in next version.


> 
>>>> +int __slim_driver_register(struct slim_driver *drv, struct module *owner)
>>>> +{
>>>> +	drv->driver.bus = &slimbus_type;
>>>> +	drv->driver.owner = owner;
>>>> +	return driver_register(&drv->driver);
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(__slim_driver_register);
>>>
>>> any reason to use __ for this API?
>>
>> This is made inline with __platfrom_driver_register() suggested in v5
>> review.
> 
> I guess Greg is best person to make this call :)
> 

Forgot to put original comment in v5 by Arnd: 
https://lkml.org/lkml/2016/4/28/179


>>>> +static void of_register_slim_devices(struct slim_controller *ctrl)
>>>> +{
>>>> +	struct device *dev = &ctrl->dev;
>>>> +	struct device_node *node;
>>>> +
>>>> +	if (!ctrl->dev.of_node)
>>>> +		return;
>>>> +
>>>> +	for_each_child_of_node(ctrl->dev.of_node, node) {
>>>> +		struct slim_device *slim;
>>>> +		const char *compat = NULL;
>>>> +		char *p, *tok;
>>>> +		int reg[2], ret;
>>>> +
>>>> +		slim = kzalloc(sizeof(*slim), GFP_KERNEL);
>>>> +		if (!slim)
>>>> +			continue;
>>>> +
>>>> +		slim->dev.of_node = of_node_get(node);
>>>> +
>>>> +		compat = of_get_property(node, "compatible", NULL);
>>>> +		if (!compat)
>>>> +			continue;
>>>> +
>>>> +		p = kasprintf(GFP_KERNEL, "%s", compat + strlen("slim"));
>>>> +
>>>> +		tok = strsep(&p, ",");
>>>> +		if (!tok) {
>>>> +			dev_err(dev, "No valid Manufacturer ID found\n");
>>>> +			kfree(p);
>>>> +			continue;
>>>> +		}
>>>> +		slim->e_addr.manf_id = str2hex(tok);
>>>> +
>>>> +		tok = strsep(&p, ",");
>>>> +		if (!tok) {
>>>> +			dev_err(dev, "No valid Product ID found\n");
>>>> +			kfree(p);
>>>> +			continue;
>>>> +		}
>>>> +		slim->e_addr.prod_code = str2hex(tok);
>>>> +		kfree(p);
>>>> +
>>>> +		ret = of_property_read_u32_array(node, "reg", reg, 2);
>>>> +		if (ret) {
>>>> +			dev_err(dev, "Device and Instance id not found:%d\n",
>>>> +				ret);
>>>> +			continue;
>>>> +		}
>>>> +		slim->e_addr.dev_index = reg[0];
>>>> +		slim->e_addr.instance = reg[1];
>>>> +
>>>> +		ret = slim_add_device(ctrl, slim);
>>>
>>> okay this is good stuff. So we scan the DT for slimbus devices and register
>>> them here. Same stuff we can do with ACPI :)
>>>
>>> then why do we need the of register stuff I commented earlier. A Slimbus
>>> device can work irrespective of firmware type and registers using various
>>> ids. The platform will scan firmware (dt/acpi) create devices and load
>>> drivers against them generically.  Apart from this code we ideally should
>>> not have any DT parts in the bus, do you agree?
>>
>> I partly agree with you, as all the devices on slimbus might not be in a
>> discoverable state. Such devices would need some sort of power up sequence
>> which what the of_wrapper and the match function are trying to achieve.
>> Driver probe will be called based on the compatible match which would then
>> power up/reset the device so that it can announce itself and the device_up()
>> would be called at that point.
>>
>> Your comment is 100% true, If the devices are in discoverable state, in such
>> case we would not need any DT entires as you said.
> 
> Yes you are right. Since the device need to be powered up thru side band we
> cannot live without using firmware (acpi/dt)
> 
> Now consider the below scheme:
>   - The Bus scans device node of the controller (acpi/dt), as
>     above and find the slim devices and adds them. The ID needs to be
>     extracted from firmware (acpi/dt), we sure need to set the right firmware
>     node for the device
>   - Drivers register based on ID, no need to make it DT/ACPI aware
>   - Match function is invoked and driver probed
>   - Sideband mechanism kick in and power up device and it announces on the
>     bus
> 

I will make id_table mandatory in next version, which should remove the 
of_matching function and code should look as you suggested.

> In case it is already powered up, it can announce being up earlier.
> 
> FWIW i am using above method with ACPI on SoundWire.
Ah..okay

> 
>>
>>>
>>>> +		if (ret)
>>>> +			dev_err(dev, "of_slim device register err:%d\n", ret);
>>>> +	}
>>>> +}
>>>> +
>>>> +/**
>>>> + * slim_register_controller: Controller bring-up and registration.
...
>>>> +
>>>> +	mutex_init(&ctrl->m_ctrl);
>>>> +	ret = device_register(&ctrl->dev);
>>>
>>> one more device_register?? Can you explain why
>>>
>>
>> This is a device for each controller.
> 
> wont the controller have its own platform_device?

Reason could be that slim_register controller can be called from any 
code not just platform devices..


> 
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On Tue, Oct 10, 2017 at 06:21:34PM +0100, Srinivas Kandagatla wrote:
> On 10/10/17 17:49, Vinod Koul wrote:

> >>>>+static int slim_device_probe(struct device *dev)
> >>>>+{
> >>>>+	struct slim_device	*sbdev;
> >>>>+	struct slim_driver	*sbdrv;
> >>>>+	int status = 0;
> >>>>+
> >>>>+	sbdev = to_slim_device(dev);
> >>>>+	sbdrv = to_slim_driver(dev->driver);
> >>>>+
> >>>>+	sbdev->driver = sbdrv;
> >>>>+
> >>>>+	if (sbdrv->probe)
> >>>>+		status = sbdrv->probe(sbdev);
> >>>>+
> >>>>+	if (status)
> >>>>+		sbdev->driver = NULL;
> >>>>+	else if (sbdrv->device_up)
> >>>>+		schedule_slim_report(sbdev->ctrl, sbdev, true);
> >>>
> >>>can you please explain what this is trying to do?
> >>
> >>It is scheduling a device_up() callback in workqueue for reporting
> >>discovered device.
> >
> >any reason for that? Would the device not announce itself on the bus and
> >then you can synchronously update the device.
> You are correct,  Device should announce itself in all cases. core should
> only call this callback only when device is announced, it does not make
> sense for this call in slim_device_probe(). Will remove it from here in next
> version.

Okay great. Btw do you need a notify being scheduled in those cases? I guess
your controller would get an interrupt and you will handle that in bottom
half and then cll this, so why not call in the bottom half?

> >>>>+/**
> >>>>+ * slim_register_controller: Controller bring-up and registration.
> ...
> >>>>+
> >>>>+	mutex_init(&ctrl->m_ctrl);
> >>>>+	ret = device_register(&ctrl->dev);
> >>>
> >>>one more device_register?? Can you explain why
> >>>
> >>
> >>This is a device for each controller.
> >
> >wont the controller have its own platform_device?
> 
> Reason could be that slim_register controller can be called from any code
> not just platform devices..

ah which cases would those be. I was expecting that you would have a
platform_device as a slimbus controller which would call slim_register?

On 11/10/17 05:07, Vinod Koul wrote:
> On Tue, Oct 10, 2017 at 06:21:34PM +0100, Srinivas Kandagatla wrote:
>> On 10/10/17 17:49, Vinod Koul wrote:
> 
>>>>>> +static int slim_device_probe(struct device *dev)
>>>>>> +{
>>>>>> +	struct slim_device	*sbdev;
>>>>>> +	struct slim_driver	*sbdrv;
>>>>>> +	int status = 0;
>>>>>> +
>>>>>> +	sbdev = to_slim_device(dev);
>>>>>> +	sbdrv = to_slim_driver(dev->driver);
>>>>>> +
>>>>>> +	sbdev->driver = sbdrv;
>>>>>> +
>>>>>> +	if (sbdrv->probe)
>>>>>> +		status = sbdrv->probe(sbdev);
>>>>>> +
>>>>>> +	if (status)
>>>>>> +		sbdev->driver = NULL;
>>>>>> +	else if (sbdrv->device_up)
>>>>>> +		schedule_slim_report(sbdev->ctrl, sbdev, true);
>>>>>
>>>>> can you please explain what this is trying to do?
>>>>
>>>> It is scheduling a device_up() callback in workqueue for reporting
>>>> discovered device.
>>>
>>> any reason for that? Would the device not announce itself on the bus and
>>> then you can synchronously update the device.
>> You are correct,  Device should announce itself in all cases. core should
>> only call this callback only when device is announced, it does not make
>> sense for this call in slim_device_probe(). Will remove it from here in next
>> version.
> 
> Okay great. Btw do you need a notify being scheduled in those cases? I guess
> your controller would get an interrupt and you will handle that in bottom
> half and then cll this, so why not call in the bottom half?
> 
That makes sense, I will optimize this path, It looks like there are 2 
workqueues in this path. We should be able to get rid of one work-queue.



>>>>>> +/**
>>>>>> + * slim_register_controller: Controller bring-up and registration.
>> ...
>>>>>> +
>>>>>> +	mutex_init(&ctrl->m_ctrl);
>>>>>> +	ret = device_register(&ctrl->dev);
>>>>>
>>>>> one more device_register?? Can you explain why
>>>>>
>>>>
>>>> This is a device for each controller.
>>>
>>> wont the controller have its own platform_device?
>>
>> Reason could be that slim_register controller can be called from any code
>> not just platform devices..
> 
> ah which cases would those be. I was expecting that you would have a
> platform_device as a slimbus controller which would call slim_register?
As of now there is only one controller which uses platform driver, but 
in future there might be more, but this is something which makes the 
slimbus core more flexible.


> 
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On Wed, Oct 11, 2017 at 10:42:23AM +0100, Srinivas Kandagatla wrote:
> On 11/10/17 05:07, Vinod Koul wrote:
> >On Tue, Oct 10, 2017 at 06:21:34PM +0100, Srinivas Kandagatla wrote:
> >>On 10/10/17 17:49, Vinod Koul wrote:

> >>>>>>+/**
> >>>>>>+ * slim_register_controller: Controller bring-up and registration.
> >>...
> >>>>>>+
> >>>>>>+	mutex_init(&ctrl->m_ctrl);
> >>>>>>+	ret = device_register(&ctrl->dev);
> >>>>>
> >>>>>one more device_register?? Can you explain why
> >>>>>
> >>>>
> >>>>This is a device for each controller.
> >>>
> >>>wont the controller have its own platform_device?
> >>
> >>Reason could be that slim_register controller can be called from any code
> >>not just platform devices..
> >
> >ah which cases would those be. I was expecting that you would have a
> >platform_device as a slimbus controller which would call slim_register?
> As of now there is only one controller which uses platform driver, but in
> future there might be more, but this is something which makes the slimbus
> core more flexible.

even if you have more controllers wouldn't we have similar number of platform
devices. Each instance of the link/controller would have its device node.

Thanks

On Tue, Oct 10, 2017 at 01:34:48PM +0100, Srinivas Kandagatla wrote:
> On 10/10/17 11:05, Charles Keepax wrote:

Please delete unneeded context from mails when replying.  Doing this
makes it much easier to find your reply in the message, helping ensure
it won't be missed by people scrolling through the irrelevant quoted
material.

> > This does sort of make sense but kinda makes the code a bit ugly
> > parsing the MID and PID. Some parts will support SLIMBus and also
> > other control interfaces, which means they would need to add an
> > additional compatible string just for SLIMBus. It also breaks
> > the normal conventions of vendor,part and finally it makes the
> > compatible strings really unreadable which will be a bit annoying
> > when looking at DTs.

> This change was made inline to the comments provided in previous version of
> the patch https://lkml.org/lkml/2016/5/3/576

I'm not sure I really agree with Rob here - while Slimbus is notionally
discoverable I don't think I ever saw a practical system which relied on
that for enumeration.  In real systems the discoverability is more of a
complexity to be worked around than anything else.

On 11/10/17 11:21, Vinod Koul wrote:
>>> ah which cases would those be. I was expecting that you would have a
>>> platform_device as a slimbus controller which would call slim_register?
>> As of now there is only one controller which uses platform driver, but in
>> future there might be more, but this is something which makes the slimbus
>> core more flexible.
> even if you have more controllers wouldn't we have similar number of platform
> devices. Each instance of the link/controller would have its device node.
>
Yep, I will give at try and see in next version!


thanks,
srini


> Thanks
> -- ~Vinod
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On Fri, Oct 06, 2017 at 05:51:30PM +0200, srinivas.kandagatla@linaro.org wrote:
> From: Sagar Dharia <sdharia@codeaurora.org>
> 
> SLIMbus (Serial Low Power Interchip Media Bus) is a specification
> developed by MIPI (Mobile Industry Processor Interface) alliance.
> SLIMbus is a 2-wire implementation, which is used to communicate with
> peripheral components like audio-codec.
> SLIMbus uses Time-Division-Multiplexing to accommodate multiple data
> channels, and control channel. Control channel has messages to do
> device-enumeration, messages to send/receive control-data to/from
> slimbus devices, messages for port/channel management, and messages to
> do bandwidth allocation.
> The framework supports multiple instances of the bus (1 controller per
> bus), and multiple slave devices per controller.
> 
> This patch does device enumeration, logical address assignment,
> informing device when the device reports present/absent etc.
> Reporting present may need the driver to do the needful (e.g. turning
> on voltage regulators powering the device). Additionally device is
> probed when it reports present if that device doesn't need any such
> steps mentioned above.
> 
> Signed-off-by: Sagar Dharia <sdharia@codeaurora.org>
> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
> ---
>  Documentation/devicetree/bindings/slimbus/bus.txt |  57 ++
>  Documentation/slimbus/summary                     | 109 ++++
>  drivers/Kconfig                                   |   2 +
>  drivers/Makefile                                  |   1 +
>  drivers/slimbus/Kconfig                           |  11 +
>  drivers/slimbus/Makefile                          |   5 +
>  drivers/slimbus/slim-core.c                       | 695 ++++++++++++++++++++++
>  include/linux/mod_devicetable.h                   |  13 +
>  include/linux/slimbus.h                           | 299 ++++++++++
>  9 files changed, 1192 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/slimbus/bus.txt
>  create mode 100644 Documentation/slimbus/summary
>  create mode 100644 drivers/slimbus/Kconfig
>  create mode 100644 drivers/slimbus/Makefile
>  create mode 100644 drivers/slimbus/slim-core.c
>  create mode 100644 include/linux/slimbus.h
> 
> diff --git a/Documentation/devicetree/bindings/slimbus/bus.txt b/Documentation/devicetree/bindings/slimbus/bus.txt
> new file mode 100644
> index 0000000..cb658bb
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/slimbus/bus.txt
> @@ -0,0 +1,57 @@
> +SLIM(Serial Low Power Interchip Media Bus) bus
> +
> +SLIMbus is a 2-wire bus, and is used to communicate with peripheral
> +components like audio-codec.
> +
> +Controller is a normal device using binding for whatever bus it is
> +on (e.g. platform bus).
> +Required property for SLIMbus controller node:
> +- compatible	- name of SLIMbus controller following generic names
> +		recommended practice.
> +- #address-cells - should be 2
> +- #size-cells	- should be 0
> +
> +No other properties are required in the SLIMbus controller bus node.
> +
> +Child nodes:
> +Every SLIMbus controller node can contain zero or more child nodes
> +representing slave devices on the bus. Every SLIMbus slave device is
> +uniquely determined by the enumeration address containing 4 fields:
> +Manufacturer ID, Product code, Device index, and Instance value for
> +the device.
> +If child node is not present and it is instantiated after device
> +discovery (slave device reporting itself present).
> +
> +In some cases it may be necessary to describe non-probeable device
> +details such as non-standard ways of powering up a device. In
> +such cases, child nodes for those devices will be present as
> +slaves of the slimbus-controller, as detailed below.
> +
> +Required property for SLIMbus child node if it is present:
> +- reg		- Is Duplex (Device index, Instance ID) from Enumeration
> +		  Address.
> +		  Device Index Uniquely identifies multiple Devices within
> +		  a single Component.
> +		  Instance ID Is for the cases where multiple Devices of the
> +		  same type or Class are attached to the bus.
> +
> +- compatible	-"slimMID,PID". The textual representation of Manufacturer ID,
> +	 	  Product Code, shall be in lower case hexadecimal with leading
> +		  zeroes suppressed
> +
> +SLIMbus example for Qualcomm's slimbus manager component:
> +
> +	slim@28080000 {
> +		compatible = "qcom,slim-msm";
> +		reg = <0x28080000 0x2000>,
> +		interrupts = <0 33 0>;
> +		clocks = <&lcc SLIMBUS_SRC>, <&lcc AUDIO_SLIMBUS_CLK>;
> +		clock-names = "iface_clk", "core_clk";
> +		#address-cells = <2>;
> +		#size-cells = <0>;
> +
> +		codec: wcd9310@1{
> +			compatible = "slim217,60"";
> +			reg = <1 0>;
> +		};
> +	};
> diff --git a/Documentation/slimbus/summary b/Documentation/slimbus/summary
> new file mode 100644
> index 0000000..e7f90bb
> --- /dev/null
> +++ b/Documentation/slimbus/summary
> @@ -0,0 +1,109 @@
> +Overview of Linux kernel SLIMbus support
> +========================================
> +
> +What is SLIMbus?
> +----------------
> +SLIMbus (Serial Low Power Interchip Media Bus) is a specification developed by
> +MIPI (Mobile Industry Processor Interface) alliance. The bus uses master/slave
> +configuration, and is a 2-wire multi-drop implementation (clock, and data).
> +
> +Currently, SLIMbus is used to interface between application processors of SoCs
> +(System-on-Chip) and peripheral components (typically codec).SLIMbus uses
> +Time-Division-Multiplexing to accommodate multiple data channels, and
> +a control channel.
> +
> +The control channel is used for various control functions such as bus
> +management, configuration and status updates.These messages can be unicast (e.g.
> +reading/writing device specific values), or multicast (e.g. data channel
> +reconfiguration sequence is a broadcast message announced to all devices)
> +
> +A data channel is used for data-transfer between 2 Slimbus devices. Data
> +channel uses dedicated ports on the device.
> +
> +Hardware description:
> +---------------------
> +Slimbus specification has different types of device classifications based on
> +their capabilities.
> +A manager device is responsible for enumeration, configuration, and dynamic
> +channel allocation. Every bus has 1 active manager.
> +
> +A generic device is a device providing application functionality (e.g. codec).
> +
> +Framer device is responsible for clocking the bus, and transmitting frame-sync
> +and framing information on the bus.
> +
> +Each SLIMbus component has an interface device for monitoring physical layer.
> +
> +Typically each SoC contains SLIMbus component having 1 manager, 1 framer device,
> +1 generic device (for data channel support), and 1 interface device.
> +External peripheral SLIMbus component usually has 1 generic device (for
> +functionality/data channel support), and an associated interface device.
> +The generic device's registers are mapped as 'value elements' so that they can
> +be written/read using Slimbus control channel exchanging control/status type of
> +information.
> +In case there are multiple framer devices on the same bus, manager device is
> +responsible to select the active-framer for clocking the bus.
> +
> +Per specification, Slimbus uses "clock gears" to do power management based on
> +current frequency and bandwidth requirements. There are 10 clock gears and each
> +gear changes the Slimbus frequency to be twice its previous gear.

Does the spec mandate 10 clock gears or its controller property?

> +
> +Each device has a 6-byte enumeration-address and the manager assigns every
> +device with a 1-byte logical address after the devices report presence on the
> +bus.
> +
> +Software description:
> +---------------------
> +There are 2 types of SLIMbus drivers:
> +
> +slim_controller represents a 'controller' for SLIMbus. This driver should
> +implement duties needed by the SoC (manager device, associated
> +interface device for monitoring the layers and reporting errors, default
> +framer device).
> +
> +slim_device represents the 'generic device/component' for SLIMbus, and a
> +slim_driver should implement driver for that slim_device.
> +
> +Device notifications to the driver:
> +-----------------------------------
> +Since SLIMbus devices have mechanisms for reporting their presence, the
> +framework allows drivers to bind when corresponding devices report their
> +presence on the bus.
> +However, it is possible that the driver needs to be probed
> +first so that it can enable corresponding SLIMbus devie (e.g. power it up and/or
> +take it out of reset). To support that behavior, the framework allows drivers
> +to probe first as well  (e.g. using standard DeviceTree compatbility field).
> +This creates the necessity for the driver to know when the device is functional
> +(i.e. reported present). device_up callback is used for that reason when the
> +device reports present and is assigned a logical address by the controller.
> +
> +Similarly, SLIMbus devices 'report absent' when they go down. A 'device_down'
> +callback notifies the driver when the device reports absent and its logical
> +address assignment is invalidated by the controller.

Is the same logical address assign when it reports present again?

> +
> +Another notification "boot_device" is used to notify the slim_driver when
> +controller resets the bus. This notification allows the driver to take necessary
> +steps to boot the device so that it's functional after the bus has been reset.
> +
> +Clock-pause:
> +------------
> +SLIMbus mandates that a reconfiguration sequence (known as clock-pause) be
> +broadcast to all active devices on the bus before the bus can enter low-power
> +mode. Controller uses this sequence when it decides to enter low-power mode so
> +that corresponding clocks and/or power-rails can be turned off to save power.
> +Clock-pause is exited by waking up framer device (if controller driver initiates
> +exiting low power mode), or by toggling the data line (if a slave device wants
> +to initiate it).
> +
> +Messaging APIs:
> +---------------
> +The framework supports APIs to exchange control-information with a SLIMbus
> +device. APIs can be synchronous or asynchronous.
> +From controller's perspective, multiple buffers can be queued to/from
> +hardware for sending/receiving data using slim_ctrl_buf circular buffer.
> +The header file <linux/slimbus.h> has more documentation about messaging APIs.
> +
> +-----------------------------------------------------------------
> +<Sections will be added to this document when port/channel bandwidth management
> +support, multi-xfer APIs are added to the framework>
> +------------------------------------------------------------------
> diff --git a/drivers/Kconfig b/drivers/Kconfig
> index 505c676..8010c67 100644
> --- a/drivers/Kconfig
> +++ b/drivers/Kconfig
> @@ -208,4 +208,6 @@ source "drivers/tee/Kconfig"
>  
>  source "drivers/mux/Kconfig"
>  
> +source "drivers/slimbus/Kconfig"
> +
>  endmenu
> diff --git a/drivers/Makefile b/drivers/Makefile
> index d90fdc4..0449c7c 100644
> --- a/drivers/Makefile
> +++ b/drivers/Makefile
> @@ -86,6 +86,7 @@ obj-$(CONFIG_MTD)		+= mtd/
>  obj-$(CONFIG_SPI)		+= spi/
>  obj-$(CONFIG_SPMI)		+= spmi/
>  obj-$(CONFIG_HSI)		+= hsi/
> +obj-$(CONFIG_SLIMBUS)		+= slimbus/
>  obj-y				+= net/
>  obj-$(CONFIG_ATM)		+= atm/
>  obj-$(CONFIG_FUSION)		+= message/
> diff --git a/drivers/slimbus/Kconfig b/drivers/slimbus/Kconfig
> new file mode 100644
> index 0000000..f0b118a
> --- /dev/null
> +++ b/drivers/slimbus/Kconfig
> @@ -0,0 +1,11 @@
> +#
> +# SLIMBUS driver configuration
> +#
> +menuconfig SLIMBUS
> +	tristate "Slimbus support"
> +	help
> +	  Slimbus is standard interface between System-on-Chip and audio codec,
> +	  and other peripheral components in typical embedded systems.
> +
> +	  If unsure, choose N.
> +
> diff --git a/drivers/slimbus/Makefile b/drivers/slimbus/Makefile
> new file mode 100644
> index 0000000..f580704
> --- /dev/null
> +++ b/drivers/slimbus/Makefile
> @@ -0,0 +1,5 @@
> +#
> +# Makefile for kernel slimbus framework.
> +#
> +obj-$(CONFIG_SLIMBUS)			+= slimbus.o
> +slimbus-y				:= slim-core.o
> diff --git a/drivers/slimbus/slim-core.c b/drivers/slimbus/slim-core.c
> new file mode 100644
> index 0000000..de3ef79
> --- /dev/null
> +++ b/drivers/slimbus/slim-core.c
> @@ -0,0 +1,695 @@
> +/* Copyright (c) 2011-2017, The Linux Foundation. All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 and
> + * only version 2 as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/errno.h>
> +#include <linux/slab.h>
> +#include <linux/init.h>
> +#include <linux/completion.h>
> +#include <linux/idr.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/slimbus.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +
> +static DEFINE_MUTEX(slim_lock);
> +static DEFINE_IDR(ctrl_idr);
> +
> +static bool slim_eaddr_equal(struct slim_eaddr *a, struct slim_eaddr *b)
> +{
> +
> +	return (a->manf_id == b->manf_id &&
> +		a->prod_code == b->prod_code &&
> +		a->dev_index == b->dev_index &&
> +		a->instance == b->instance);
> +}
> +
> +static const struct slim_device_id *slim_match(const struct slim_device_id *id,
> +					       const struct slim_device *sbdev)
> +{
> +	while (id->manf_id != 0 || id->prod_code != 0) {
> +		if (id->manf_id == sbdev->e_addr.manf_id &&
> +		    id->prod_code == sbdev->e_addr.prod_code &&
> +		    id->dev_index == sbdev->e_addr.dev_index)
> +			return id;
> +		id++;
> +	}
> +	return NULL;
> +}
> +
> +static int slim_device_match(struct device *dev, struct device_driver *drv)
> +{
> +	struct slim_device *sbdev = to_slim_device(dev);
> +	struct slim_driver *sbdrv = to_slim_driver(drv);
> +
> +	/* Attempt an OF style match first */
> +	if (of_driver_match_device(dev, drv))
> +		return 1;
> +
> +	/* Then try to match against the id table */
> +	if (sbdrv->id_table)
> +		return slim_match(sbdrv->id_table, sbdev) != NULL;
> +
> +	return 0;
> +}
> +
> +struct sb_report_wd {
> +	struct work_struct wd;
> +	struct slim_device *sbdev;
> +	bool report;
> +};
> +
> +static void slim_report(struct work_struct *work)
> +{
> +	struct slim_driver *sbdrv;
> +	struct sb_report_wd *sbw = container_of(work, struct sb_report_wd, wd);
> +	struct slim_device *sbdev = sbw->sbdev;
> +
> +	mutex_lock(&sbdev->report_lock);
> +	if (!sbdev->dev.driver)
> +		goto report_exit;
> +
> +	/* check if device-up or down needs to be called */
> +	if ((!sbdev->reported && !sbdev->notified) ||
> +	    (sbdev->reported && sbdev->notified))
> +		goto report_exit;
> +
> +	sbdrv = to_slim_driver(sbdev->dev.driver);
> +
> +	/**
> +	 * address no longer valid, means device reported absent, whereas
> +	 * address valid, means device reported present
> +	 */
> +	if (sbdev->notified && !sbdev->reported) {
> +		sbdev->notified = false;
> +		if (sbdrv->device_down)
> +			sbdrv->device_down(sbdev);
> +	} else if (!sbdev->notified && sbdev->reported) {
> +		sbdev->notified = true;
> +		if (sbdrv->device_up)
> +			sbdrv->device_up(sbdev);
> +	}
> +report_exit:
> +	mutex_unlock(&sbdev->report_lock);
> +	kfree(sbw);
> +}
> +
> +/**
> + * Report callbacks(device_up, device_down) are implemented by slimbus-devices.
> + * The calls are scheduled into a workqueue to avoid holding up controller
> + * initialization/tear-down.
> + */
> +static void schedule_slim_report(struct slim_controller *ctrl,
> +				 struct slim_device *sb, bool report)
> +{
> +	struct sb_report_wd *sbw;
> +
> +	dev_dbg(&ctrl->dev, "report:%d for slave:%s\n", report, sb->name);
> +
> +	sbw = kmalloc(sizeof(*sbw), GFP_KERNEL);
> +	if (!sbw)
> +		return;
> +
> +	INIT_WORK(&sbw->wd, slim_report);
> +	sbw->sbdev = sb;
> +	sbw->report = report;
> +	if (!queue_work(ctrl->wq, &sbw->wd)) {
> +		dev_err(&ctrl->dev, "failed to queue report:%d slave:%s\n",
> +				    report, sb->name);
> +		kfree(sbw);
> +	}
> +}
> +
> +static int slim_device_probe(struct device *dev)
> +{
> +	struct slim_device	*sbdev;
> +	struct slim_driver	*sbdrv;
> +	int status = 0;
> +
> +	sbdev = to_slim_device(dev);
> +	sbdrv = to_slim_driver(dev->driver);
> +
> +	sbdev->driver = sbdrv;
> +
> +	if (sbdrv->probe)
> +		status = sbdrv->probe(sbdev);
> +
> +	if (status)
> +		sbdev->driver = NULL;
> +	else if (sbdrv->device_up)
> +		schedule_slim_report(sbdev->ctrl, sbdev, true);
> +
> +	return status;
> +}
> +
> +static int slim_device_remove(struct device *dev)
> +{
> +	struct slim_device *sbdev;
> +	struct slim_driver *sbdrv;
> +	int status = 0;
> +
> +	sbdev = to_slim_device(dev);
> +	if (!dev->driver)
> +		return 0;
> +
> +	sbdrv = to_slim_driver(dev->driver);
> +	if (sbdrv->remove)
> +		status = sbdrv->remove(sbdev);
> +
> +	mutex_lock(&sbdev->report_lock);
> +	sbdev->notified = false;
> +	if (status == 0)
> +		sbdev->driver = NULL;
> +	mutex_unlock(&sbdev->report_lock);
> +	return status;
> +}
> +
> +struct bus_type slimbus_type = {
> +	.name		= "slimbus",
> +	.match		= slim_device_match,
> +	.probe		= slim_device_probe,
> +	.remove		= slim_device_remove,
> +};
> +EXPORT_SYMBOL_GPL(slimbus_type);
> +
> +/**
> + * slim_driver_register: Client driver registration with slimbus
> + * @drv:Client driver to be associated with client-device.
> + * @owner: owning module/driver
> + * This API will register the client driver with the slimbus
> + * It is called from the driver's module-init function.
> + */
> +int __slim_driver_register(struct slim_driver *drv, struct module *owner)
> +{
> +	drv->driver.bus = &slimbus_type;
> +	drv->driver.owner = owner;
> +	return driver_register(&drv->driver);
> +}
> +EXPORT_SYMBOL_GPL(__slim_driver_register);
> +
> +/**
> + * slim_driver_unregister: Undo effect of slim_driver_register
> + * @drv: Client driver to be unregistered
> + */
> +void slim_driver_unregister(struct slim_driver *drv)
> +{
> +	if (drv)
> +		driver_unregister(&drv->driver);
> +}
> +EXPORT_SYMBOL_GPL(slim_driver_unregister);
> +
> +static struct slim_controller *slim_ctrl_get(struct slim_controller *ctrl)
> +{
> +	if (!ctrl || !get_device(&ctrl->dev))
> +		return NULL;
> +
> +	return ctrl;
> +}
> +
> +static void slim_ctrl_put(struct slim_controller *ctrl)
> +{
> +	if (ctrl)
> +		put_device(&ctrl->dev);
> +}
> +
> +static void slim_dev_release(struct device *dev)
> +{
> +	struct slim_device *sbdev = to_slim_device(dev);
> +
> +	slim_ctrl_put(sbdev->ctrl);
> +	kfree(sbdev->name);
> +	kfree(sbdev);
> +}
> +
> +static int slim_add_device(struct slim_controller *ctrl,
> +			   struct slim_device *sbdev)
> +{
> +	sbdev->dev.bus = &slimbus_type;
> +	sbdev->dev.parent = &ctrl->dev;
> +	sbdev->dev.release = slim_dev_release;
> +	sbdev->dev.driver = NULL;
> +	sbdev->ctrl = ctrl;
> +
> +	slim_ctrl_get(ctrl);
> +	sbdev->name = kasprintf(GFP_KERNEL, "%x:%x:%x:%x",
> +					sbdev->e_addr.manf_id,
> +					sbdev->e_addr.prod_code,
> +					sbdev->e_addr.dev_index,
> +					sbdev->e_addr.instance);
> +	if (!sbdev->name)
> +		return -ENOMEM;
> +
> +	dev_set_name(&sbdev->dev, "%s", sbdev->name);
> +	mutex_init(&sbdev->report_lock);
> +
> +	/* probe slave on this controller */
> +	return device_register(&sbdev->dev);
> +}
> +
> +/* Helper to get hex Manufacturer ID and Product id from compatible */
> +static unsigned long str2hex(unsigned char *str)
> +{
> +	int value = 0;
> +
> +	while (*str) {
> +		char c = *str++;
> +
> +		value = value << 4;
> +		if (c >= '0' && c <= '9')
> +			value |= (c - '0');
> +		if (c >= 'a' && c <= 'f')
> +			value |= (c - 'a' + 10);
> +
> +	}
> +
> +	return value;
> +}
> +
> +/* OF helpers for SLIMbus */
> +static void of_register_slim_devices(struct slim_controller *ctrl)
> +{
> +	struct device *dev = &ctrl->dev;
> +	struct device_node *node;
> +
> +	if (!ctrl->dev.of_node)
> +		return;
> +
> +	for_each_child_of_node(ctrl->dev.of_node, node) {
> +		struct slim_device *slim;
> +		const char *compat = NULL;
> +		char *p, *tok;
> +		int reg[2], ret;
> +
> +		slim = kzalloc(sizeof(*slim), GFP_KERNEL);
> +		if (!slim)
> +			continue;
> +
> +		slim->dev.of_node = of_node_get(node);
> +
> +		compat = of_get_property(node, "compatible", NULL);
> +		if (!compat)
> +			continue;
> +
> +		p = kasprintf(GFP_KERNEL, "%s", compat + strlen("slim"));
> +
> +		tok = strsep(&p, ",");
> +		if (!tok) {
> +			dev_err(dev, "No valid Manufacturer ID found\n");
> +			kfree(p);
> +			continue;
> +		}
> +		slim->e_addr.manf_id = str2hex(tok);
> +
> +		tok = strsep(&p, ",");
> +		if (!tok) {
> +			dev_err(dev, "No valid Product ID found\n");
> +			kfree(p);
> +			continue;
> +		}
> +		slim->e_addr.prod_code = str2hex(tok);
> +		kfree(p);
> +
> +		ret = of_property_read_u32_array(node, "reg", reg, 2);
> +		if (ret) {
> +			dev_err(dev, "Device and Instance id not found:%d\n",
> +				ret);
> +			continue;
> +		}
> +		slim->e_addr.dev_index = reg[0];
> +		slim->e_addr.instance = reg[1];
> +
> +		ret = slim_add_device(ctrl, slim);
> +		if (ret)
> +			dev_err(dev, "of_slim device register err:%d\n", ret);
> +	}
> +}
> +
> +/**
> + * slim_register_controller: Controller bring-up and registration.
> + * @ctrl: Controller to be registered.
> + * A controller is registered with the framework using this API.
> + * If devices on a controller were registered before controller,
> + * this will make sure that they get probed when controller is up
> + */
> +int slim_register_controller(struct slim_controller *ctrl)
> +{
> +	int id, ret = 0;
> +
> +	mutex_lock(&slim_lock);
> +	id = idr_alloc(&ctrl_idr, ctrl, ctrl->nr, -1, GFP_KERNEL);
> +	mutex_unlock(&slim_lock);
> +
> +	if (id < 0)
> +		return id;
> +
> +	ctrl->nr = id;
> +
> +	dev_set_name(&ctrl->dev, "sb-%d", ctrl->nr);
> +	ctrl->num_dev = 0;
> +
> +	if (!ctrl->min_cg)
> +		ctrl->min_cg = SLIM_MIN_CLK_GEAR;
> +	if (!ctrl->max_cg)
> +		ctrl->max_cg = SLIM_MAX_CLK_GEAR;
> +
> +	mutex_init(&ctrl->m_ctrl);
> +	ret = device_register(&ctrl->dev);
> +	if (ret)
> +		goto dev_reg_failed;
> +
> +	dev_dbg(&ctrl->dev, "Bus [%s] registered:dev:%p\n",
> +		ctrl->name, &ctrl->dev);
> +
> +	ctrl->wq = create_singlethread_workqueue(dev_name(&ctrl->dev));
> +	if (!ctrl->wq)
> +		goto err_workq_failed;
> +
> +	of_register_slim_devices(ctrl);
> +
> +	return 0;
> +
> +err_workq_failed:
> +	device_unregister(&ctrl->dev);
> +dev_reg_failed:
> +	mutex_lock(&slim_lock);
> +	idr_remove(&ctrl_idr, ctrl->nr);
> +	mutex_unlock(&slim_lock);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(slim_register_controller);
> +
> +/* slim_remove_device: Remove the effect of slim_add_device() */
> +static void slim_remove_device(struct slim_device *sbdev)
> +{
> +	device_unregister(&sbdev->dev);
> +}
> +
> +static int slim_ctrl_remove_device(struct device *dev, void *null)
> +{
> +	slim_remove_device(to_slim_device(dev));
> +	return 0;
> +}
> +
> +/**
> + * slim_del_controller: Controller tear-down.
> + * @ctrl: Controller to tear-down.
> + */
> +int slim_del_controller(struct slim_controller *ctrl)
> +{
> +	struct slim_controller *found;
> +
> +	/* First make sure that this bus was added */
> +	mutex_lock(&slim_lock);
> +	found = idr_find(&ctrl_idr, ctrl->nr);
> +	mutex_unlock(&slim_lock);
> +	if (found != ctrl)
> +		return -EINVAL;
> +
> +	/* Remove all clients */
> +	device_for_each_child(&ctrl->dev, NULL, slim_ctrl_remove_device);
> +
> +
> +	destroy_workqueue(ctrl->wq);
> +
> +	/* free bus id */
> +	mutex_lock(&slim_lock);
> +	idr_remove(&ctrl_idr, ctrl->nr);
> +	mutex_unlock(&slim_lock);
> +
> +	device_unregister(&ctrl->dev);
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(slim_del_controller);
> +
> +/**
> + * slim_report_absent: Controller calls this function when a device
> + *	reports absent, OR when the device cannot be communicated with
> + * @sbdev: Device that cannot be reached, or sent report absent
> + */
> +void slim_report_absent(struct slim_device *sbdev)
> +{
> +	struct slim_controller *ctrl;
> +	int i;
> +
> +	if (!sbdev)
> +		return;
> +	ctrl = sbdev->ctrl;
> +	if (!ctrl)
> +		return;
> +
> +	/* invalidate logical addresses */
> +	mutex_lock(&ctrl->m_ctrl);
> +	for (i = 0; i < ctrl->num_dev; i++) {
> +		if (sbdev->laddr == ctrl->addrt[i].laddr)
> +			ctrl->addrt[i].valid = false;
> +	}
> +	mutex_unlock(&ctrl->m_ctrl);
> +
> +	mutex_lock(&sbdev->report_lock);
> +	sbdev->reported = false;
> +	schedule_slim_report(ctrl, sbdev, false);
> +	mutex_unlock(&sbdev->report_lock);
> +}
> +EXPORT_SYMBOL_GPL(slim_report_absent);
> +
> +static int slim_boot_child(struct device *dev, void *unused)
> +{
> +	struct slim_driver *sbdrv;
> +	struct slim_device *sbdev = to_slim_device(dev);
> +
> +	if (sbdev && sbdev->dev.driver) {
> +		sbdrv = to_slim_driver(sbdev->dev.driver);
> +		if (sbdrv->boot_device)
> +			sbdrv->boot_device(sbdev);
> +	}
> +	return 0;
> +}
> +
> +static int slim_match_dev(struct device *dev, void *data)
> +{
> +	struct slim_eaddr *e_addr = data;
> +	struct slim_device *slim = to_slim_device(dev);
> +
> +	return slim_eaddr_equal(&slim->e_addr, e_addr);
> +}
> +
> +/**
> + * slim_framer_booted: This function is called by controller after the active
> + * framer has booted (using Bus Reset sequence, or after it has shutdown and has
> + * come back up).
> + * @ctrl: Controller associated with this framer
> + * Components, devices on the bus may be in undefined state,
> + * and this function triggers their drivers to do the needful
> + * to bring them back in Reset state so that they can acquire sync, report
> + * present and be operational again.
> + */
> +void slim_framer_booted(struct slim_controller *ctrl)
> +{
> +	if (!ctrl)
> +		return;
> +
> +	device_for_each_child(&ctrl->dev, NULL, slim_boot_child);
> +}
> +EXPORT_SYMBOL_GPL(slim_framer_booted);
> +
> +/**
> + * slim_query_device: Query and get handle to a device.
> + * @ctrl: Controller on which this device will be added/queried
> + * @e_addr: Enumeration address of the device to be queried
> + * Returns pointer to a device if it has already reported. Creates a new
> + * device and returns pointer to it if the device has not yet enumerated.
> + */
> +struct slim_device *slim_query_device(struct slim_controller *ctrl,
> +				      struct slim_eaddr *e_addr)
> +{
> +	struct device *dev;
> +	struct slim_device *slim = NULL;
> +
> +	dev = device_find_child(&ctrl->dev, e_addr, slim_match_dev);
> +	if (dev) {
> +		slim = to_slim_device(dev);
> +		return slim;
> +	}
> +
> +	slim = kzalloc(sizeof(struct slim_device), GFP_KERNEL);
> +	if (IS_ERR(slim))
> +		return NULL;
> +
> +	slim->e_addr = *e_addr;
> +	if (slim_add_device(ctrl, slim) != 0) {
> +		kfree(slim);
> +		return NULL;
> +	}
> +	return slim;
> +}
> +EXPORT_SYMBOL_GPL(slim_query_device);
> +
> +static int ctrl_getaddr_entry(struct slim_controller *ctrl,
> +			      struct slim_eaddr *eaddr, u8 *entry)
> +{
> +	int i;
> +
> +	for (i = 0; i < ctrl->num_dev; i++) {
> +		if (ctrl->addrt[i].valid &&
> +		    slim_eaddr_equal(&ctrl->addrt[i].eaddr, eaddr)) {
> +			*entry = i;
> +			return 0;
> +		}
> +	}
> +	return -ENXIO;
> +}
> +
> +/**
> + * slim_assign_laddr: Assign logical address to a device enumerated.
> + * @ctrl: Controller with which device is enumerated.
> + * @e_addr: Enumeration address of the device.
> + * @laddr: Return logical address (if valid flag is false)
> + * @valid: true if laddr holds a valid address that controller wants to
> + *	set for this enumeration address. Otherwise framework sets index into
> + *	address table as logical address.
> + * Called by controller in response to REPORT_PRESENT. Framework will assign
> + * a logical address to this enumeration address.
> + * Function returns -EXFULL to indicate that all logical addresses are already
> + * taken.
> + */
> +int slim_assign_laddr(struct slim_controller *ctrl, struct slim_eaddr *e_addr,
> +		      u8 *laddr, bool valid)
> +{
> +	int ret;
> +	u8 i = 0;
> +	bool exists = false;
> +	struct slim_device *slim;
> +	struct slim_addrt *temp;
> +
> +	mutex_lock(&ctrl->m_ctrl);
> +	/* already assigned */
> +	if (ctrl_getaddr_entry(ctrl, e_addr, &i) == 0) {
> +		*laddr = ctrl->addrt[i].laddr;
> +		exists = true;
> +	} else {
> +		if (ctrl->num_dev >= (SLIM_LA_MANAGER - 1)) {
> +			ret = -EXFULL;
> +			goto ret_assigned_laddr;
> +		}
> +		for (i = 0; i < ctrl->num_dev; i++) {
> +			if (ctrl->addrt[i].valid == false)
> +				break;
> +		}
> +		if (i == ctrl->num_dev) {
> +			temp = krealloc(ctrl->addrt,
> +					(ctrl->num_dev + 1) *
> +					sizeof(struct slim_addrt),
> +					GFP_KERNEL);
> +			if (!temp) {
> +				ret = -ENOMEM;
> +				goto ret_assigned_laddr;
> +			}
> +			ctrl->addrt = temp;
> +			ctrl->num_dev++;
> +		}
> +		ctrl->addrt[i].eaddr = *e_addr;
> +		ctrl->addrt[i].valid = true;
> +
> +		/* Preferred address is index into table */
> +		if (!valid)
> +			*laddr = i;
> +	}
> +
> +	ret = ctrl->set_laddr(ctrl, &ctrl->addrt[i].eaddr, *laddr);
> +	if (ret) {
> +		ctrl->addrt[i].valid = false;
> +		goto ret_assigned_laddr;
> +	}
> +	ctrl->addrt[i].laddr = *laddr;
> +
> +ret_assigned_laddr:
> +	mutex_unlock(&ctrl->m_ctrl);
> +	if (exists || ret)
> +		return ret;
> +
> +	dev_info(&ctrl->dev, "setting slimbus l-addr:%x, ea:%x,%x,%x,%x\n",
> +		*laddr, e_addr->manf_id, e_addr->prod_code,
> +		e_addr->dev_index, e_addr->instance);
> +
> +	/**
> +	 * Add this device to list of devices on this controller if it's
> +	 * not already present
> +	 */
> +	slim = slim_query_device(ctrl, e_addr);
> +	if (!slim) {
> +		ret = -ENODEV;
> +	} else {
> +		struct slim_driver *sbdrv;
> +
> +		slim->laddr = *laddr;
> +		mutex_lock(&slim->report_lock);
> +		slim->reported = true;
> +		if (slim->dev.driver) {
> +			sbdrv = to_slim_driver(slim->dev.driver);
> +			if (sbdrv->device_up)
> +				schedule_slim_report(ctrl, slim, true);
> +		}
> +		mutex_unlock(&slim->report_lock);
> +	}
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(slim_assign_laddr);
> +
> +/**
> + * slim_get_logical_addr: Return the logical address of a slimbus device.
> + * @sb: client handle requesting the address.
> + * @e_addr: Enumeration address of the device.
> + * @laddr: output buffer to store the address
> + * context: can sleep
> + * -EINVAL is returned in case of invalid parameters, and -ENXIO is returned if
> + *  the device with this enumeration address is not found.
> + */
> +int slim_get_logical_addr(struct slim_device *sb, struct slim_eaddr *e_addr,
> +			  u8 *laddr)
> +{
> +	int ret;
> +	u8 entry;
> +	struct slim_controller *ctrl = sb->ctrl;
> +
> +	if (!ctrl || !laddr || !e_addr)
> +		return -EINVAL;
> +
> +	mutex_lock(&ctrl->m_ctrl);
> +	ret = ctrl_getaddr_entry(ctrl, e_addr, &entry);
> +	if (!ret)
> +		*laddr = ctrl->addrt[entry].laddr;
> +	mutex_unlock(&ctrl->m_ctrl);
> +
> +	if (ret == -ENXIO && ctrl->get_laddr) {
> +		ret = ctrl->get_laddr(ctrl, e_addr, laddr);
> +		if (!ret)
> +			ret = slim_assign_laddr(ctrl, e_addr, laddr, true);
> +	}
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(slim_get_logical_addr);
> +
> +static void __exit slimbus_exit(void)
> +{
> +	bus_unregister(&slimbus_type);
> +}
> +module_exit(slimbus_exit);
> +
> +static int __init slimbus_init(void)
> +{
> +	return bus_register(&slimbus_type);
> +}
> +postcore_initcall(slimbus_init);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_VERSION("0.1");
> +MODULE_DESCRIPTION("Slimbus module");
> diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
> index 694cebb..015e5f6 100644
> --- a/include/linux/mod_devicetable.h
> +++ b/include/linux/mod_devicetable.h
> @@ -448,6 +448,19 @@ struct spi_device_id {
>  	kernel_ulong_t driver_data;	/* Data private to the driver */
>  };
>  
> +/* SLIMbus */
> +
> +#define SLIMBUS_NAME_SIZE	32
> +#define SLIMBUS_MODULE_PREFIX	"slim:"
> +
> +struct slim_device_id {
> +	__u16 manf_id, prod_code;
> +	__u8 dev_index, instance;
> +
> +	/* Data private to the driver */
> +	kernel_ulong_t driver_data;
> +};
> +
>  #define SPMI_NAME_SIZE	32
>  #define SPMI_MODULE_PREFIX "spmi:"
>  
> diff --git a/include/linux/slimbus.h b/include/linux/slimbus.h
> new file mode 100644
> index 0000000..b5064b6
> --- /dev/null
> +++ b/include/linux/slimbus.h
> @@ -0,0 +1,299 @@
> +/* Copyright (c) 2011-2017, The Linux Foundation. All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 and
> + * only version 2 as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#ifndef _LINUX_SLIMBUS_H
> +#define _LINUX_SLIMBUS_H
> +#include <linux/module.h>
> +#include <linux/device.h>
> +#include <linux/mutex.h>
> +#include <linux/mod_devicetable.h>
> +
> +/**
> + * Interfaces between SLIMbus manager drivers, SLIMbus client drivers, and
> + * SLIMbus infrastructure.
> + */
> +
> +extern struct bus_type slimbus_type;
> +
> +/* Standard values per SLIMbus spec needed by controllers and devices */
> +#define SLIM_CL_PER_SUPERFRAME		6144
> +#define SLIM_CL_PER_SUPERFRAME_DIV8	(SLIM_CL_PER_SUPERFRAME >> 3)
> +#define SLIM_MAX_CLK_GEAR		10
> +#define SLIM_MIN_CLK_GEAR		1
> +#define SLIM_CL_PER_SL			4
> +#define SLIM_SL_PER_SUPERFRAME		(SLIM_CL_PER_SUPERFRAME >> 2)
> +#define SLIM_FRM_SLOTS_PER_SUPERFRAME	16
> +#define SLIM_GDE_SLOTS_PER_SUPERFRAME	2
> +
> +struct slim_controller;
> +struct slim_device;
> +
> +/**
> + * struct slim_eaddr: Enumeration address for a slimbus device
> + * @manf_id: Manufacturer Id for the device
> + * @prod_code: Product code
> + * @dev_index: Device index
> + * @instance: Instance value
> + */
> +struct slim_eaddr {
> +	u16 manf_id;
> +	u16 prod_code;
> +	u8 dev_index;
> +	u8 instance;
> +};
> +
> +/**
> + * struct slim_framer - Represents Slimbus framer.
> + * Every controller may have multiple framers. There is 1 active framer device
> + * responsible for clocking the bus.
> + * Manager is responsible for framer hand-over.
> + * @dev: Driver model representation of the device.
> + * @e_addr: Enumeration address of the framer.
> + * @rootfreq: Root Frequency at which the framer can run. This is maximum
> + *	frequency ('clock gear 10') at which the bus can operate.
> + * @superfreq: Superframes per root frequency. Every frame is 6144 bits.
> + */
> +struct slim_framer {
> +	struct device		dev;
> +	struct slim_eaddr	e_addr;
> +	int			rootfreq;
> +	int			superfreq;
> +};
> +
> +#define to_slim_framer(d) container_of(d, struct slim_framer, dev)
> +
> +/**
> + * struct slim_addrt: slimbus address used internally by the slimbus framework.
> + * @valid: If the device is present. Valid is set to false when device reports
> + *	absent.
> + * @eaddr: Enumeration address
> + * @laddr: It is possible that controller will set a predefined logical address
> + *	rather than the one assigned by framework. (i.e. logical address may
> + *	not be same as index into this table). This entry will store the
> + *	logical address value for this enumeration address.
> + */
> +struct slim_addrt {
> +	bool			valid;
> +	struct slim_eaddr	eaddr;
> +	u8			laddr;
> +};
> +
> +/* SLIMbus message types. Related to interpretation of message code. */
> +#define SLIM_MSG_MT_CORE			0x0
> +#define SLIM_MSG_MT_DEST_REFERRED_CLASS		0x1
> +#define SLIM_MSG_MT_DEST_REFERRED_USER		0x2
> +#define SLIM_MSG_MT_SRC_REFERRED_CLASS		0x5
> +#define SLIM_MSG_MT_SRC_REFERRED_USER		0x6
> +
> +/* SLIMbus core type Message Codes. */
> +/* Device management messages used by this framework */
> +#define SLIM_MSG_MC_REPORT_PRESENT               0x1
> +#define SLIM_MSG_MC_ASSIGN_LOGICAL_ADDRESS       0x2
> +#define SLIM_MSG_MC_REPORT_ABSENT                0xF
> +
> +/* Destination type Values */
> +#define SLIM_MSG_DEST_LOGICALADDR	0
> +#define SLIM_MSG_DEST_ENUMADDR		1
> +#define	SLIM_MSG_DEST_BROADCAST		3
> +
> +/**
> + * struct slim_controller: Controls every instance of SLIMbus
> + *				(similar to 'master' on SPI)
> + *	'Manager device' is responsible for  device management, bandwidth
> + *	allocation, channel setup, and port associations per channel.
> + *	Device management means Logical address assignment/removal based on
> + *	enumeration (report-present, report-absent) if a device.
> + *	Bandwidth allocation is done dynamically by the manager based on active
> + *	channels on the bus, message-bandwidth requests made by slimbus devices.
> + *	Based on current bandwidth usage, manager chooses a frequency to run
> + *	the bus at (in steps of 'clock-gear', 1 through 10, each clock gear
> + *	representing twice the frequency than the previous gear).
> + *	Manager is also responsible for entering (and exiting) low-power-mode
> + *	(known as 'clock pause').
> + *	Manager can do handover of framer if there are multiple framers on the
> + *	bus and a certain usecase warrants using certain framer to avoid keeping
> + *	previous framer being powered-on.
> + *
> + *	Controller here performs duties of the manager device, and 'interface
> + *	device'. Interface device is responsible for monitoring the bus and
> + *	reporting information such as loss-of-synchronization, data
> + *	slot-collision.
> + * @dev: Device interface to this driver
> + * @nr: Board-specific number identifier for this controller/bus
> + * @list: Link with other slimbus controllers
> + * @name: Name for this controller
> + * @min_cg: Minimum clock gear supported by this controller (default value: 1)
> + * @max_cg: Maximum clock gear supported by this controller (default value: 10)
> + * @clkgear: Current clock gear in which this bus is running
> + * @a_framer: Active framer which is clocking the bus managed by this controller
> + * @m_ctrl: Mutex protecting controller data structures
> + * @addrt: Logical address table
> + * @num_dev: Number of active slimbus slaves on this bus
> + * @wq: Workqueue per controller used to notify devices when they report present
> + * @xfer_msg: Transfer a message on this controller (this can be a broadcast
> + *	control/status message like data channel setup, or a unicast message
> + *	like value element read/write.

xfer_msg element is not present in structure.

> + * @set_laddr: Setup logical address at laddr for the slave with elemental
> + *	address e_addr. Drivers implementing controller will be expected to
> + *	send unicast message to this device with its logical address.
> + * @get_laddr: It is possible that controller needs to set fixed logical
> + *	address table and get_laddr can be used in that case so that controller
> + *	can do this assignment.
> + */
> +struct slim_controller {
> +	struct device		dev;
> +	unsigned int		nr;
> +	char			name[SLIMBUS_NAME_SIZE];
> +	int			min_cg;
> +	int			max_cg;
> +	int			clkgear;
> +	struct slim_framer	*a_framer;
> +	struct mutex		m_ctrl;
> +	struct slim_addrt	*addrt;
> +	u8			num_dev;
> +	struct workqueue_struct *wq;
> +	int			(*set_laddr)(struct slim_controller *ctrl,
> +					     struct slim_eaddr *ea, u8 laddr);
> +	int			(*get_laddr)(struct slim_controller *ctrl,
> +					     struct slim_eaddr *ea, u8 *laddr);
> +};
> +
> +#define to_slim_controller(d) container_of(d, struct slim_controller, dev)
> +
> +/**
> + * struct slim_driver: Slimbus 'generic device' (slave) device driver
> + *				(similar to 'spi_device' on SPI)
> + * @probe: Binds this driver to a slimbus device.
> + * @remove: Unbinds this driver from the slimbus device.
> + * @shutdown: Standard shutdown callback used during powerdown/halt.
> + * @suspend: Standard suspend callback used during system suspend
> + * @resume: Standard resume callback used during system resume
> + * @device_up: This callback is called when the device reports present and
> + *		gets a logical address assigned to it
> + * @device_down: This callback is called when device reports absent, or the
> + *		bus goes down. Device will report present when bus is up and
> + *		device_up callback will be called again when that happens
> + * @boot_device: This callback is called after framer is booted.
> + *		Driver should do the needful to boot the device,
> + *		so that device acquires sync and be operational.
> + * @driver: Slimbus device drivers should initialize name and owner field of
> + *	this structure
> + * @id_table: List of slimbus devices supported by this driver
> + */
> +struct slim_driver {
> +	int				(*probe)(struct slim_device *sl);
> +	int				(*remove)(struct slim_device *sl);
> +	void				(*shutdown)(struct slim_device *sl);
> +	int				(*suspend)(struct slim_device *sl,
> +						   pm_message_t pmesg);
> +	int				(*resume)(struct slim_device *sl);
> +	int				(*device_up)(struct slim_device *sl);
> +	int				(*device_down)(struct slim_device *sl);
> +	int				(*boot_device)(struct slim_device *sl);
> +
> +	struct device_driver		driver;
> +	const struct slim_device_id	*id_table;
> +};
> +
> +#define to_slim_driver(d) container_of(d, struct slim_driver, driver)
> +
> +/**
> + * Client/device handle (struct slim_device):
> + * ------------------------------------------
> + *  This is the client/device handle returned when a slimbus
> + *  device is registered with a controller.
> + *  Pointer to this structure is used by client-driver as a handle.
> + *  @dev: Driver model representation of the device.
> + *  @name: Name of driver to use with this device.
> + *  @e_addr: Enumeration address of this device.
> + *  @driver: Device's driver. Pointer to access routines.
> + *  @ctrl: Slimbus controller managing the bus hosting this device.
> + *  @laddr: 1-byte Logical address of this device.
> + *  @reported: Flag to indicate whether this device reported present. The flag
> + *	is set when device reports present, and is reset when it reports
> + *	absent. This flag alongwith notified flag below is used to call
> + *	device_up, or device_down callbacks for driver of this device.
> + *  @notified: Flag to indicate whether this device has been notified. The
> + *	device may report present multiple times, but should be notified only
> + *	first time it has reported present.
> + *  @report_lock: Lock to protect reporting and notification for this device
> + */
> +struct slim_device {
> +	struct device		dev;
> +	char		*name;
> +	struct slim_eaddr	e_addr;
> +	struct slim_driver	*driver;
> +	struct slim_controller	*ctrl;
> +	u8			laddr;
> +	bool			reported;
> +	bool			notified;
> +	struct mutex		report_lock;
> +};
> +
> +#define to_slim_device(d) container_of(d, struct slim_device, dev)
> +
> +/* Manager's logical address is set to 0xFF per spec */
> +#define SLIM_LA_MANAGER 0xFF
> +
> +int slim_get_logical_addr(struct slim_device *sb,
> +				 struct slim_eaddr *e_addr, u8 *laddr);
> +
> +/*
> + * use a macro to avoid include chaining to get THIS_MODULE
> + */
> +#define slim_driver_register(drv) \
> +	__slim_driver_register(drv, THIS_MODULE)
> +
> +int __slim_driver_register(struct slim_driver *drv, struct module *owner);
> +
> +void slim_driver_unregister(struct slim_driver *drv);
> +
> +/**
> + * module_slim_driver() - Helper macro for registering a slimbus driver
> + * @__slimbus_driver: slimbus_driver struct
> + *
> + * Helper macro for slimbus drivers which do not do anything special in module
> + * init/exit. This eliminates a lot of boilerplate. Each module may only
> + * use this macro once, and calling it replaces module_init() and module_exit()
> + */
> +#define module_slim_driver(__slim_driver) \
> +	module_driver(__slim_driver, slim_driver_register, \
> +			slim_driver_unregister)
> +
> +int slim_del_controller(struct slim_controller *ctrl);
> +int slim_assign_laddr(struct slim_controller *ctrl,
> +		      struct slim_eaddr *e_addr, u8 *laddr, bool valid);
> +void slim_report_absent(struct slim_device *sbdev);
> +void slim_framer_booted(struct slim_controller *ctrl);
> +int slim_register_controller(struct slim_controller *ctrl);
> +
> +static inline void *slim_get_ctrldata(const struct slim_controller *dev)
> +{
> +	return dev_get_drvdata(&dev->dev);
> +}
> +
> +static inline void slim_set_ctrldata(struct slim_controller *dev, void *data)
> +{
> +	dev_set_drvdata(&dev->dev, data);
> +}
> +
> +static inline void *slim_get_devicedata(const struct slim_device *dev)
> +{
> +	return dev_get_drvdata(&dev->dev);
> +}
> +
> +static inline void slim_set_devicedata(struct slim_device *dev, void *data)
> +{
> +	dev_set_drvdata(&dev->dev, data);
> +}
> +
> +#endif /* _LINUX_SLIMBUS_H */
> -- 
> 2.9.3
> 
> _______________________________________________
> Alsa-devel mailing list
> Alsa-devel@alsa-project.org
> http://mailman.alsa-project.org/mailman/listinfo/alsa-devel

On 12/10/17 12:01, Sanyog Kale wrote:
> On Fri, Oct 06, 2017 at 05:51:30PM +0200, srinivas.kandagatla@linaro.org wrote:
>> From: Sagar Dharia <sdharia@codeaurora.org>
>>
>> +Per specification, Slimbus uses "clock gears" to do power management based on
>> +current frequency and bandwidth requirements. There are 10 clock gears and each
>> +gear changes the Slimbus frequency to be twice its previous gear.
> 
> Does the spec mandate 10 clock gears or its controller property?

Clock Gear Construct is part of SLIMbus Specs to alter clk frequency.


>> +Device notifications to the driver:
>> +-----------------------------------
>> +Since SLIMbus devices have mechanisms for reporting their presence, the
>> +framework allows drivers to bind when corresponding devices report their
>> +presence on the bus.
>> +However, it is possible that the driver needs to be probed
>> +first so that it can enable corresponding SLIMbus devie (e.g. power it up and/or
>> +take it out of reset). To support that behavior, the framework allows drivers
>> +to probe first as well  (e.g. using standard DeviceTree compatbility field).
>> +This creates the necessity for the driver to know when the device is functional
>> +(i.e. reported present). device_up callback is used for that reason when the
>> +device reports present and is assigned a logical address by the controller.
>> +
>> +Similarly, SLIMbus devices 'report absent' when they go down. A 'device_down'
>> +callback notifies the driver when the device reports absent and its logical
>> +address assignment is invalidated by the controller.
> 
> Is the same logical address assign when it reports present again?

Currently, Code as it is will pick the first available logical address. 
If required we can add logic in future to assign same logical address.
For now the code is simple.



>> + *
>> + *	Controller here performs duties of the manager device, and 'interface
>> + *	device'. Interface device is responsible for monitoring the bus and
>> + *	reporting information such as loss-of-synchronization, data
>> + *	slot-collision.
>> + * @dev: Device interface to this driver
>> + * @nr: Board-specific number identifier for this controller/bus
>> + * @list: Link with other slimbus controllers
>> + * @name: Name for this controller
>> + * @min_cg: Minimum clock gear supported by this controller (default value: 1)
>> + * @max_cg: Maximum clock gear supported by this controller (default value: 10)
>> + * @clkgear: Current clock gear in which this bus is running
>> + * @a_framer: Active framer which is clocking the bus managed by this controller
>> + * @m_ctrl: Mutex protecting controller data structures
>> + * @addrt: Logical address table
>> + * @num_dev: Number of active slimbus slaves on this bus
>> + * @wq: Workqueue per controller used to notify devices when they report present
>> + * @xfer_msg: Transfer a message on this controller (this can be a broadcast
>> + *	control/status message like data channel setup, or a unicast message
>> + *	like value element read/write.
> 
> xfer_msg element is not present in structure.
> 

Thanks, it will be fixed in next version.

thanks,
Srini


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On Fri, Oct 06, 2017 at 05:51:30PM +0200, srinivas.kandagatla@linaro.org wrote:
> From: Sagar Dharia <sdharia@codeaurora.org>
> 
> SLIMbus (Serial Low Power Interchip Media Bus) is a specification
> developed by MIPI (Mobile Industry Processor Interface) alliance.
> SLIMbus is a 2-wire implementation, which is used to communicate with
> peripheral components like audio-codec.
> SLIMbus uses Time-Division-Multiplexing to accommodate multiple data
> channels, and control channel. Control channel has messages to do
> device-enumeration, messages to send/receive control-data to/from
> slimbus devices, messages for port/channel management, and messages to
> do bandwidth allocation.
> The framework supports multiple instances of the bus (1 controller per
> bus), and multiple slave devices per controller.
> 
> This patch does device enumeration, logical address assignment,
> informing device when the device reports present/absent etc.
> Reporting present may need the driver to do the needful (e.g. turning
> on voltage regulators powering the device). Additionally device is
> probed when it reports present if that device doesn't need any such
> steps mentioned above.
> 
> Signed-off-by: Sagar Dharia <sdharia@codeaurora.org>
> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
> ---
>  Documentation/devicetree/bindings/slimbus/bus.txt |  57 ++

Split to separate patch.

>  Documentation/slimbus/summary                     | 109 ++++
>  drivers/Kconfig                                   |   2 +
>  drivers/Makefile                                  |   1 +
>  drivers/slimbus/Kconfig                           |  11 +
>  drivers/slimbus/Makefile                          |   5 +
>  drivers/slimbus/slim-core.c                       | 695 ++++++++++++++++++++++
>  include/linux/mod_devicetable.h                   |  13 +
>  include/linux/slimbus.h                           | 299 ++++++++++
>  9 files changed, 1192 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/slimbus/bus.txt
>  create mode 100644 Documentation/slimbus/summary
>  create mode 100644 drivers/slimbus/Kconfig
>  create mode 100644 drivers/slimbus/Makefile
>  create mode 100644 drivers/slimbus/slim-core.c
>  create mode 100644 include/linux/slimbus.h
> 
> diff --git a/Documentation/devicetree/bindings/slimbus/bus.txt b/Documentation/devicetree/bindings/slimbus/bus.txt
> new file mode 100644
> index 0000000..cb658bb
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/slimbus/bus.txt
> @@ -0,0 +1,57 @@
> +SLIM(Serial Low Power Interchip Media Bus) bus
> +
> +SLIMbus is a 2-wire bus, and is used to communicate with peripheral
> +components like audio-codec.
> +
> +Controller is a normal device using binding for whatever bus it is
> +on (e.g. platform bus).

I can't have a PCI based slimbus controller? "platform bus" is a 
Linuxism.

> +Required property for SLIMbus controller node:
> +- compatible	- name of SLIMbus controller following generic names
> +		recommended practice.

generic names aren't recommended. Allowed with some conditons, yes.

> +- #address-cells - should be 2

You used 4 for your controller.

> +- #size-cells	- should be 0
> +
> +No other properties are required in the SLIMbus controller bus node.

That's not a useful statement. Almost every controller probably has 
other required properties.

> +
> +Child nodes:
> +Every SLIMbus controller node can contain zero or more child nodes
> +representing slave devices on the bus. Every SLIMbus slave device is
> +uniquely determined by the enumeration address containing 4 fields:
> +Manufacturer ID, Product code, Device index, and Instance value for
> +the device.
> +If child node is not present and it is instantiated after device
> +discovery (slave device reporting itself present).
> +
> +In some cases it may be necessary to describe non-probeable device
> +details such as non-standard ways of powering up a device. In
> +such cases, child nodes for those devices will be present as
> +slaves of the slimbus-controller, as detailed below.
> +
> +Required property for SLIMbus child node if it is present:
> +- reg		- Is Duplex (Device index, Instance ID) from Enumeration
> +		  Address.
> +		  Device Index Uniquely identifies multiple Devices within
> +		  a single Component.
> +		  Instance ID Is for the cases where multiple Devices of the
> +		  same type or Class are attached to the bus.
> +
> +- compatible	-"slimMID,PID". The textual representation of Manufacturer ID,
> +	 	  Product Code, shall be in lower case hexadecimal with leading
> +		  zeroes suppressed
> +
> +SLIMbus example for Qualcomm's slimbus manager component:
> +
> +	slim@28080000 {
> +		compatible = "qcom,slim-msm";
> +		reg = <0x28080000 0x2000>,
> +		interrupts = <0 33 0>;
> +		clocks = <&lcc SLIMBUS_SRC>, <&lcc AUDIO_SLIMBUS_CLK>;
> +		clock-names = "iface_clk", "core_clk";
> +		#address-cells = <2>;
> +		#size-cells = <0>;
> +
> +		codec: wcd9310@1{

Is '1' by itself unique enough because you have 2 address cells. The 
unit-address is typically split up into fields with commas unless it's 
just a memory address. Anyway, you need to define the unit address 
format in this doc.

> +			compatible = "slim217,60"";
> +			reg = <1 0>;
> +		};
> +	};
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On 13/10/17 20:26, Rob Herring wrote:
> On Fri, Oct 06, 2017 at 05:51:30PM +0200, srinivas.kandagatla@linaro.org wrote:
>> From: Sagar Dharia <sdharia@codeaurora.org>
>>
>> SLIMbus (Serial Low Power Interchip Media Bus) is a specification
>> developed by MIPI (Mobile Industry Processor Interface) alliance.
>> SLIMbus is a 2-wire implementation, which is used to communicate with
>> peripheral components like audio-codec.
>> SLIMbus uses Time-Division-Multiplexing to accommodate multiple data
>> channels, and control channel. Control channel has messages to do
>> device-enumeration, messages to send/receive control-data to/from
>> slimbus devices, messages for port/channel management, and messages to
>> do bandwidth allocation.
>> The framework supports multiple instances of the bus (1 controller per
>> bus), and multiple slave devices per controller.
>>
>> This patch does device enumeration, logical address assignment,
>> informing device when the device reports present/absent etc.
>> Reporting present may need the driver to do the needful (e.g. turning
>> on voltage regulators powering the device). Additionally device is
>> probed when it reports present if that device doesn't need any such
>> steps mentioned above.
>>
>> Signed-off-by: Sagar Dharia <sdharia@codeaurora.org>
>> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
>> ---
>>   Documentation/devicetree/bindings/slimbus/bus.txt |  57 ++
> 
> Split to separate patch.

Will do this in next patch.
It was suggested by Arnd in v5, may be just of_parse code can be merged 
in this patch and the bindings made as separate patch.


> 
>>   Documentation/slimbus/summary                     | 109 ++++
>>   drivers/Kconfig                                   |   2 +
>>   drivers/Makefile                                  |   1 +
>>   drivers/slimbus/Kconfig                           |  11 +
>>   drivers/slimbus/Makefile                          |   5 +
>>   drivers/slimbus/slim-core.c                       | 695 ++++++++++++++++++++++
>>   include/linux/mod_devicetable.h                   |  13 +
>>   include/linux/slimbus.h                           | 299 ++++++++++
>>   9 files changed, 1192 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/slimbus/bus.txt
>>   create mode 100644 Documentation/slimbus/summary
>>   create mode 100644 drivers/slimbus/Kconfig
>>   create mode 100644 drivers/slimbus/Makefile
>>   create mode 100644 drivers/slimbus/slim-core.c
>>   create mode 100644 include/linux/slimbus.h
>>
>> diff --git a/Documentation/devicetree/bindings/slimbus/bus.txt b/Documentation/devicetree/bindings/slimbus/bus.txt
>> new file mode 100644
>> index 0000000..cb658bb
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/slimbus/bus.txt
>> @@ -0,0 +1,57 @@
>> +SLIM(Serial Low Power Interchip Media Bus) bus
>> +
>> +SLIMbus is a 2-wire bus, and is used to communicate with peripheral
>> +components like audio-codec.
>> +
>> +Controller is a normal device using binding for whatever bus it is
>> +on (e.g. platform bus).
> 
> I can't have a PCI based slimbus controller? "platform bus" is a
> Linuxism.
I agree, Will remove this Linuxism from the bindings.

> 
>> +Required property for SLIMbus controller node:
>> +- compatible	- name of SLIMbus controller following generic names
>> +		recommended practice.
> 
> generic names aren't recommended. Allowed with some conditons, yes.
> 
>> +- #address-cells - should be 2
> 
> You used 4 for your controller.

It should be actually 2. I will fix such mismatches in the other patches.

> 
>> +- #size-cells	- should be 0
>> +
>> +No other properties are required in the SLIMbus controller bus node.
> 
> That's not a useful statement. Almost every controller probably has
> other required properties.
Yep, will get rid of this in next patch.
> 
>> +
>> +Child nodes:
>> +Every SLIMbus controller node can contain zero or more child nodes
>> +representing slave devices on the bus. Every SLIMbus slave device is
>> +uniquely determined by the enumeration address containing 4 fields:
>> +Manufacturer ID, Product code, Device index, and Instance value for
>> +the device.
>> +If child node is not present and it is instantiated after device
>> +discovery (slave device reporting itself present).
>> +
>> +In some cases it may be necessary to describe non-probeable device
>> +details such as non-standard ways of powering up a device. In
>> +such cases, child nodes for those devices will be present as
>> +slaves of the slimbus-controller, as detailed below.
>> +
>> +Required property for SLIMbus child node if it is present:
>> +- reg		- Is Duplex (Device index, Instance ID) from Enumeration
>> +		  Address.
>> +		  Device Index Uniquely identifies multiple Devices within
>> +		  a single Component.
>> +		  Instance ID Is for the cases where multiple Devices of the
>> +		  same type or Class are attached to the bus.
>> +
>> +- compatible	-"slimMID,PID". The textual representation of Manufacturer ID,
>> +	 	  Product Code, shall be in lower case hexadecimal with leading
>> +		  zeroes suppressed
>> +
>> +SLIMbus example for Qualcomm's slimbus manager component:
>> +
>> +	slim@28080000 {
>> +		compatible = "qcom,slim-msm";
>> +		reg = <0x28080000 0x2000>,
>> +		interrupts = <0 33 0>;
>> +		clocks = <&lcc SLIMBUS_SRC>, <&lcc AUDIO_SLIMBUS_CLK>;
>> +		clock-names = "iface_clk", "core_clk";
>> +		#address-cells = <2>;
>> +		#size-cells = <0>;
>> +
>> +		codec: wcd9310@1{
> 
> Is '1' by itself unique enough because you have 2 address cells. The
> unit-address is typically split up into fields with commas unless it's
> just a memory address. Anyway, you need to define the unit address
> format in this doc.
> 
Yep, this examples should be fixed with proper unit address which is 
formed by "device-id,instance-id"

device id + Instance ID makes it unique, I though I already added 
details the reg property.




>> +			compatible = "slim217,60"";
>> +			reg = <1 0>;
>> +		};
>> +	};
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On Fri 06 Oct 08:51 PDT 2017, srinivas.kandagatla@linaro.org wrote:
[..]
> diff --git a/drivers/slimbus/slim-core.c b/drivers/slimbus/slim-core.c
[..]
> +/**
> + * Report callbacks(device_up, device_down) are implemented by slimbus-devices.
> + * The calls are scheduled into a workqueue to avoid holding up controller
> + * initialization/tear-down.
> + */
> +static void schedule_slim_report(struct slim_controller *ctrl,
> +				 struct slim_device *sb, bool report)
> +{
> +	struct sb_report_wd *sbw;
> +
> +	dev_dbg(&ctrl->dev, "report:%d for slave:%s\n", report, sb->name);

This is the only place where sb->name is used in this driver. If you
instead invoke dev_*() on &sb->dev you should get prettier output and
can drop the double storage of the device name.

> +
> +	sbw = kmalloc(sizeof(*sbw), GFP_KERNEL);
> +	if (!sbw)
> +		return;
> +
> +	INIT_WORK(&sbw->wd, slim_report);
> +	sbw->sbdev = sb;
> +	sbw->report = report;
> +	if (!queue_work(ctrl->wq, &sbw->wd)) {

When a controller is torn down destroy_workqueue() is called after all
child devices has been unregistered, so this work might be scheduled
after "sb" is gone, if I get this properly.

> +		dev_err(&ctrl->dev, "failed to queue report:%d slave:%s\n",
> +				    report, sb->name);
> +		kfree(sbw);
> +	}
> +}
> +
> +static int slim_device_probe(struct device *dev)
> +{
> +	struct slim_device	*sbdev;
> +	struct slim_driver	*sbdrv;
> +	int status = 0;
> +
> +	sbdev = to_slim_device(dev);
> +	sbdrv = to_slim_driver(dev->driver);
> +
> +	sbdev->driver = sbdrv;
> +
> +	if (sbdrv->probe)
> +		status = sbdrv->probe(sbdev);

So a driver can have a probe() and device_up() or just any one of them?

And probe() is called when the controller enumerates all devices
mentioned in DT and then device_up() is called at that point in time and
when it's advertised on the bus?

Is there a reason for this split model?

> +
> +	if (status)
> +		sbdev->driver = NULL;
> +	else if (sbdrv->device_up)
> +		schedule_slim_report(sbdev->ctrl, sbdev, true);
> +
> +	return status;
> +}
> +
> +static int slim_device_remove(struct device *dev)
> +{
> +	struct slim_device *sbdev;
> +	struct slim_driver *sbdrv;
> +	int status = 0;
> +
> +	sbdev = to_slim_device(dev);
> +	if (!dev->driver)
> +		return 0;
> +
> +	sbdrv = to_slim_driver(dev->driver);
> +	if (sbdrv->remove)
> +		status = sbdrv->remove(sbdev);
> +
> +	mutex_lock(&sbdev->report_lock);
> +	sbdev->notified = false;
> +	if (status == 0)
> +		sbdev->driver = NULL;
> +	mutex_unlock(&sbdev->report_lock);
> +	return status;

device_unregister() will call device_del() which will end up in
__device_release_driver() which will call this function. Upon returning
from this function the core expect the bus to have cleaned up after the
dev (normally by calling drv->remove(dev)).

It will completely ignore the return value and continue tearing down the
rest of the core resources, e.g. three lines down it will
devres_release_all().


So you have the option of sleeping, while waiting for stuff to be
aborted/finished and then you need to clean things up.

The slim_device object itself will stick around until all references are
dropped though.

> +}
> +
> +struct bus_type slimbus_type = {
> +	.name		= "slimbus",
> +	.match		= slim_device_match,
> +	.probe		= slim_device_probe,
> +	.remove		= slim_device_remove,
> +};
> +EXPORT_SYMBOL_GPL(slimbus_type);
> +
> +/**
> + * slim_driver_register: Client driver registration with slimbus
> + * @drv:Client driver to be associated with client-device.
> + * @owner: owning module/driver
> + * This API will register the client driver with the slimbus
> + * It is called from the driver's module-init function.
> + */
> +int __slim_driver_register(struct slim_driver *drv, struct module *owner)
> +{
> +	drv->driver.bus = &slimbus_type;
> +	drv->driver.owner = owner;
> +	return driver_register(&drv->driver);
> +}
> +EXPORT_SYMBOL_GPL(__slim_driver_register);
> +
> +/**
> + * slim_driver_unregister: Undo effect of slim_driver_register
> + * @drv: Client driver to be unregistered
> + */
> +void slim_driver_unregister(struct slim_driver *drv)
> +{
> +	if (drv)

A driver invoking slim_driver_unregister(NULL) is broken, drop this
check and let it oops on the dereference instead.

> +		driver_unregister(&drv->driver);
> +}
> +EXPORT_SYMBOL_GPL(slim_driver_unregister);
> +
> +static struct slim_controller *slim_ctrl_get(struct slim_controller *ctrl)
> +{
> +	if (!ctrl || !get_device(&ctrl->dev))

ctrl can't be NULL here. In all code paths leading here it's
dereferenced multiple times already.

> +		return NULL;
> +
> +	return ctrl;
> +}
> +
> +static void slim_ctrl_put(struct slim_controller *ctrl)
> +{
> +	if (ctrl)
> +		put_device(&ctrl->dev);
> +}
> +
> +static void slim_dev_release(struct device *dev)
> +{
> +	struct slim_device *sbdev = to_slim_device(dev);
> +
> +	slim_ctrl_put(sbdev->ctrl);

As far as I can see there's no case where sbdev->ctrl will ever be NULL,
so yo can just replace this with
	put_device(&ctrl->dev);

And drop slim_ctrl_put().

> +	kfree(sbdev->name);
> +	kfree(sbdev);
> +}
> +
> +static int slim_add_device(struct slim_controller *ctrl,
> +			   struct slim_device *sbdev)
> +{
> +	sbdev->dev.bus = &slimbus_type;
> +	sbdev->dev.parent = &ctrl->dev;
> +	sbdev->dev.release = slim_dev_release;
> +	sbdev->dev.driver = NULL;
> +	sbdev->ctrl = ctrl;
> +
> +	slim_ctrl_get(ctrl);

Unfolding slim_ctrl_get(), with ctrl != NULL, gives us a container_of(),
so this can't fail. Which is good because then an error check would have
been nice.

But it also means that you can replace this with just:
	get_device(&ctrl->dev);

And drop slim_ctrl_get()

> +	sbdev->name = kasprintf(GFP_KERNEL, "%x:%x:%x:%x",
> +					sbdev->e_addr.manf_id,
> +					sbdev->e_addr.prod_code,
> +					sbdev->e_addr.dev_index,
> +					sbdev->e_addr.instance);
> +	if (!sbdev->name)
> +		return -ENOMEM;
> +
> +	dev_set_name(&sbdev->dev, "%s", sbdev->name);

This will create another copy of the same string and as noted above
there seems to be only one consumer, which could be switched over. So
you can drop above kasprintf() and just use dev_set_name to format the
name.

An added benefit is that you're not leaking the device reference from
slim_ctrl_get() on the line before.

> +	mutex_init(&sbdev->report_lock);
> +
> +	/* probe slave on this controller */
> +	return device_register(&sbdev->dev);
> +}
> +
> +/* Helper to get hex Manufacturer ID and Product id from compatible */
> +static unsigned long str2hex(unsigned char *str)

The caller of this passes char *, so you can drop the unsigned. And add
"const" while you're at it.

> +{
> +	int value = 0;
> +
> +	while (*str) {
> +		char c = *str++;
> +
> +		value = value << 4;
> +		if (c >= '0' && c <= '9')
> +			value |= (c - '0');
> +		if (c >= 'a' && c <= 'f')
> +			value |= (c - 'a' + 10);

At the cost of one more check here you can drop the line in the
documentation about this only working for lower-case hex digits.

> +
> +	}
> +
> +	return value;
> +}
> +
> +/* OF helpers for SLIMbus */
> +static void of_register_slim_devices(struct slim_controller *ctrl)
> +{
> +	struct device *dev = &ctrl->dev;
> +	struct device_node *node;
> +
> +	if (!ctrl->dev.of_node)
> +		return;
> +
> +	for_each_child_of_node(ctrl->dev.of_node, node) {
> +		struct slim_device *slim;
> +		const char *compat = NULL;
> +		char *p, *tok;
> +		int reg[2], ret;
> +
> +		slim = kzalloc(sizeof(*slim), GFP_KERNEL);

This is leaked in several places below.

> +		if (!slim)
> +			continue;
> +
> +		slim->dev.of_node = of_node_get(node);

Dito.

> +
> +		compat = of_get_property(node, "compatible", NULL);
> +		if (!compat)
> +			continue;
> +
> +		p = kasprintf(GFP_KERNEL, "%s", compat + strlen("slim"));

Allocating a new string using string formatting based on an offset from
a string we don't know the size of, just to tokenize it does not seem
like the most efficient (nor safe) way of doing this.


How about:
		ret = sscanf(compat, "slim%x,%x", &manf_id, &prod_code);
		if (ret != 2)
			error();

> +
> +		tok = strsep(&p, ",");
> +		if (!tok) {
> +			dev_err(dev, "No valid Manufacturer ID found\n");
> +			kfree(p);
> +			continue;
> +		}
> +		slim->e_addr.manf_id = str2hex(tok);
> +
> +		tok = strsep(&p, ",");
> +		if (!tok) {
> +			dev_err(dev, "No valid Product ID found\n");
> +			kfree(p);
> +			continue;
> +		}
> +		slim->e_addr.prod_code = str2hex(tok);
> +		kfree(p);
> +
> +		ret = of_property_read_u32_array(node, "reg", reg, 2);
> +		if (ret) {
> +			dev_err(dev, "Device and Instance id not found:%d\n",
> +				ret);
> +			continue;
> +		}
> +		slim->e_addr.dev_index = reg[0];
> +		slim->e_addr.instance = reg[1];
> +
> +		ret = slim_add_device(ctrl, slim);
> +		if (ret)
> +			dev_err(dev, "of_slim device register err:%d\n", ret);

Cleanup if this fails.

> +	}
> +}
> +
> +/**
> + * slim_register_controller: Controller bring-up and registration.
> + * @ctrl: Controller to be registered.
> + * A controller is registered with the framework using this API.
> + * If devices on a controller were registered before controller,
> + * this will make sure that they get probed when controller is up
> + */
> +int slim_register_controller(struct slim_controller *ctrl)
> +{
> +	int id, ret = 0;
> +
> +	mutex_lock(&slim_lock);
> +	id = idr_alloc(&ctrl_idr, ctrl, ctrl->nr, -1, GFP_KERNEL);

The purpose of ctrl_idr is to generate unique ids for the name and to
check that slim_del_controller() is only called on valid
slim_controllers.

The latter is okay to just expect the controller drivers to do right and
the prior is better done with an ida.


Also, the lower boundary should be 0, not ctrl->nr.

> +	mutex_unlock(&slim_lock);
> +
> +	if (id < 0)
> +		return id;
> +
> +	ctrl->nr = id;
> +
> +	dev_set_name(&ctrl->dev, "sb-%d", ctrl->nr);

This name is used in a lot of debug prints, can we do better?

> +	ctrl->num_dev = 0;
> +
> +	if (!ctrl->min_cg)
> +		ctrl->min_cg = SLIM_MIN_CLK_GEAR;
> +	if (!ctrl->max_cg)
> +		ctrl->max_cg = SLIM_MAX_CLK_GEAR;
> +
> +	mutex_init(&ctrl->m_ctrl);
> +	ret = device_register(&ctrl->dev);
> +	if (ret)
> +		goto dev_reg_failed;
> +
> +	dev_dbg(&ctrl->dev, "Bus [%s] registered:dev:%p\n",
> +		ctrl->name, &ctrl->dev);

This is the only place ctrl->name is used. Perhaps it would make more
sense to base the dev_name off this string, to make all these dev_*()
more useful.

> +
> +	ctrl->wq = create_singlethread_workqueue(dev_name(&ctrl->dev));
> +	if (!ctrl->wq)
> +		goto err_workq_failed;
> +
> +	of_register_slim_devices(ctrl);
> +
> +	return 0;
> +
> +err_workq_failed:
> +	device_unregister(&ctrl->dev);
> +dev_reg_failed:
> +	mutex_lock(&slim_lock);
> +	idr_remove(&ctrl_idr, ctrl->nr);
> +	mutex_unlock(&slim_lock);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(slim_register_controller);
> +
> +/* slim_remove_device: Remove the effect of slim_add_device() */
> +static void slim_remove_device(struct slim_device *sbdev)
> +{
> +	device_unregister(&sbdev->dev);
> +}
> +
> +static int slim_ctrl_remove_device(struct device *dev, void *null)
> +{
> +	slim_remove_device(to_slim_device(dev));
> +	return 0;
> +}
> +
> +/**
> + * slim_del_controller: Controller tear-down.
> + * @ctrl: Controller to tear-down.
> + */
> +int slim_del_controller(struct slim_controller *ctrl)

This is the opposite of slim_register_controller() so should it perhaps
be called slim_unregister_controller() ?

> +{
> +	struct slim_controller *found;
> +
> +	/* First make sure that this bus was added */
> +	mutex_lock(&slim_lock);
> +	found = idr_find(&ctrl_idr, ctrl->nr);
> +	mutex_unlock(&slim_lock);
> +	if (found != ctrl)
> +		return -EINVAL;

Just rely on the caller doing the right thing and just
	ida_remove(&ctrl_ida, ctrl->nr);

> +
> +	/* Remove all clients */
> +	device_for_each_child(&ctrl->dev, NULL, slim_ctrl_remove_device);
> +

As stated above there might be work items left in flight here, after the
slim_devices are released.

> +
> +	destroy_workqueue(ctrl->wq);
> +
> +	/* free bus id */
> +	mutex_lock(&slim_lock);
> +	idr_remove(&ctrl_idr, ctrl->nr);
> +	mutex_unlock(&slim_lock);
> +
> +	device_unregister(&ctrl->dev);
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(slim_del_controller);
[..]
> +/**
> + * slim_query_device: Query and get handle to a device.
> + * @ctrl: Controller on which this device will be added/queried
> + * @e_addr: Enumeration address of the device to be queried
> + * Returns pointer to a device if it has already reported. Creates a new
> + * device and returns pointer to it if the device has not yet enumerated.
> + */
> +struct slim_device *slim_query_device(struct slim_controller *ctrl,
> +				      struct slim_eaddr *e_addr)
> +{
> +	struct device *dev;
> +	struct slim_device *slim = NULL;

This will be written before read, so please don't initialize.

> +
> +	dev = device_find_child(&ctrl->dev, e_addr, slim_match_dev);
> +	if (dev) {
> +		slim = to_slim_device(dev);
> +		return slim;
> +	}
> +
> +	slim = kzalloc(sizeof(struct slim_device), GFP_KERNEL);
> +	if (IS_ERR(slim))

!slim

> +		return NULL;
> +
> +	slim->e_addr = *e_addr;
> +	if (slim_add_device(ctrl, slim) != 0) {

The idiomatic way is:

ret = fn();
if (ret) {
	failure...
}

> +		kfree(slim);
> +		return NULL;
> +	}
> +	return slim;
> +}
> +EXPORT_SYMBOL_GPL(slim_query_device);
> +
> +static int ctrl_getaddr_entry(struct slim_controller *ctrl,
> +			      struct slim_eaddr *eaddr, u8 *entry)
> +{
> +	int i;
> +
> +	for (i = 0; i < ctrl->num_dev; i++) {
> +		if (ctrl->addrt[i].valid &&
> +		    slim_eaddr_equal(&ctrl->addrt[i].eaddr, eaddr)) {
> +			*entry = i;

i will be >= 0, so it can easily be distinguished from -ENXIO. So you
could return that directly instead of passing "i" as a reference and to
get the value.

On the other hand the return value is only used as an offset in addrt[]
to read out addrt[i].laddr, so perhaps you should just return that
instead (as an int).

> +			return 0;
> +		}
> +	}
> +	return -ENXIO;
> +}
> +
> +/**
> + * slim_assign_laddr: Assign logical address to a device enumerated.

So I presume this will either report a new (not seen before) e_addr
which should cause a new device to be spawned (although it might be
already mentioned in DT) or it might be called for an existing device to
update the logical address.

Can you describe when the latter is the case? Or is this a side effect
of the code, rather than slimbus?

> + * @ctrl: Controller with which device is enumerated.
> + * @e_addr: Enumeration address of the device.
> + * @laddr: Return logical address (if valid flag is false)
> + * @valid: true if laddr holds a valid address that controller wants to
> + *	set for this enumeration address. Otherwise framework sets index into
> + *	address table as logical address.

How do you ensure this laddr is unique?

> + * Called by controller in response to REPORT_PRESENT. Framework will assign
> + * a logical address to this enumeration address.
> + * Function returns -EXFULL to indicate that all logical addresses are already
> + * taken.
> + */
> +int slim_assign_laddr(struct slim_controller *ctrl, struct slim_eaddr *e_addr,
> +		      u8 *laddr, bool valid)
> +{
> +	int ret;
> +	u8 i = 0;
> +	bool exists = false;
> +	struct slim_device *slim;
> +	struct slim_addrt *temp;
> +
> +	mutex_lock(&ctrl->m_ctrl);
> +	/* already assigned */
> +	if (ctrl_getaddr_entry(ctrl, e_addr, &i) == 0) {

So I presume this updates an existing e_addr -> laddr mapping. But this
should imply that there is an associated slim_device with this e_addr
and laddr. Shouldn't said slim_device have its laddr updated then?

> +		*laddr = ctrl->addrt[i].laddr;
> +		exists = true;
> +	} else {
> +		if (ctrl->num_dev >= (SLIM_LA_MANAGER - 1)) {
> +			ret = -EXFULL;
> +			goto ret_assigned_laddr;
> +		}
> +		for (i = 0; i < ctrl->num_dev; i++) {
> +			if (ctrl->addrt[i].valid == false)
> +				break;
> +		}
> +		if (i == ctrl->num_dev) {
> +			temp = krealloc(ctrl->addrt,
> +					(ctrl->num_dev + 1) *
> +					sizeof(struct slim_addrt),
> +					GFP_KERNEL);
> +			if (!temp) {
> +				ret = -ENOMEM;
> +				goto ret_assigned_laddr;
> +			}
> +			ctrl->addrt = temp;
> +			ctrl->num_dev++;
> +		}

This seems better handled by a list than an array that we realloc. But
better yet, this array seems to mirror the list of registered devices.

So why doesn't this function just try to resolve the slim_device with
e_addr and if not allocate a new slim_device with a free laddr. Using an
ida to keep track of used logical addresses would make this much
cleaner.

Or a idr keyed by the laddr, it would still be O(n) to scan based on
e_addr, but this logic as well as lookups by laddr would be cleaner.

> +		ctrl->addrt[i].eaddr = *e_addr;
> +		ctrl->addrt[i].valid = true;
> +
> +		/* Preferred address is index into table */
> +		if (!valid)
> +			*laddr = i;

Is this laddr available?

> +	}
> +
> +	ret = ctrl->set_laddr(ctrl, &ctrl->addrt[i].eaddr, *laddr);
> +	if (ret) {
> +		ctrl->addrt[i].valid = false;
> +		goto ret_assigned_laddr;
> +	}
> +	ctrl->addrt[i].laddr = *laddr;
> +
> +ret_assigned_laddr:
> +	mutex_unlock(&ctrl->m_ctrl);
> +	if (exists || ret)
> +		return ret;
> +
> +	dev_info(&ctrl->dev, "setting slimbus l-addr:%x, ea:%x,%x,%x,%x\n",
> +		*laddr, e_addr->manf_id, e_addr->prod_code,
> +		e_addr->dev_index, e_addr->instance);
> +
> +	/**
> +	 * Add this device to list of devices on this controller if it's
> +	 * not already present
> +	 */
> +	slim = slim_query_device(ctrl, e_addr);
> +	if (!slim) {
> +		ret = -ENODEV;
> +	} else {
> +		struct slim_driver *sbdrv;
> +
> +		slim->laddr = *laddr;
> +		mutex_lock(&slim->report_lock);
> +		slim->reported = true;
> +		if (slim->dev.driver) {
> +			sbdrv = to_slim_driver(slim->dev.driver);
> +			if (sbdrv->device_up)
> +				schedule_slim_report(ctrl, slim, true);
> +		}
> +		mutex_unlock(&slim->report_lock);

I can't help feeling that this is the one and only point where you
should call probe() on the slim_device. Are there some funky
dependencies or protocol issues that makes this infeasible?

> +	}
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(slim_assign_laddr);
> +
> +/**
> + * slim_get_logical_addr: Return the logical address of a slimbus device.
> + * @sb: client handle requesting the address.
> + * @e_addr: Enumeration address of the device.
> + * @laddr: output buffer to store the address
> + * context: can sleep
> + * -EINVAL is returned in case of invalid parameters, and -ENXIO is returned if
> + *  the device with this enumeration address is not found.
> + */
> +int slim_get_logical_addr(struct slim_device *sb, struct slim_eaddr *e_addr,
> +			  u8 *laddr)

In what case would e_addr != sb->e_addr and why can't this function just
be return sb->laddr?

> +{
> +	int ret;
> +	u8 entry;
> +	struct slim_controller *ctrl = sb->ctrl;
> +
> +	if (!ctrl || !laddr || !e_addr)
> +		return -EINVAL;
> +
> +	mutex_lock(&ctrl->m_ctrl);
> +	ret = ctrl_getaddr_entry(ctrl, e_addr, &entry);
> +	if (!ret)
> +		*laddr = ctrl->addrt[entry].laddr;
> +	mutex_unlock(&ctrl->m_ctrl);
> +
> +	if (ret == -ENXIO && ctrl->get_laddr) {
> +		ret = ctrl->get_laddr(ctrl, e_addr, laddr);
> +		if (!ret)
> +			ret = slim_assign_laddr(ctrl, e_addr, laddr, true);
> +	}
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(slim_get_logical_addr);
[..]
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_VERSION("0.1");

Who will ever update this version number? It's probably better to just
omit it.

> +MODULE_DESCRIPTION("Slimbus module");

Rather than "Slimbus module", this is actually the "Slimbus core".

> diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
[..]
> +extern struct bus_type slimbus_type;

The device struct has a "struct device_type *type", which causes this
name to be confusing. Please rename it slimbus_bus instead.

Why does this bus_type have to be known to the world?

> +
> +/* Standard values per SLIMbus spec needed by controllers and devices */
> +#define SLIM_CL_PER_SUPERFRAME		6144
> +#define SLIM_CL_PER_SUPERFRAME_DIV8	(SLIM_CL_PER_SUPERFRAME >> 3)
> +#define SLIM_MAX_CLK_GEAR		10
> +#define SLIM_MIN_CLK_GEAR		1
> +#define SLIM_CL_PER_SL			4
> +#define SLIM_SL_PER_SUPERFRAME		(SLIM_CL_PER_SUPERFRAME >> 2)
> +#define SLIM_FRM_SLOTS_PER_SUPERFRAME	16
> +#define SLIM_GDE_SLOTS_PER_SUPERFRAME	2

Keep the min/max here and move the rest to the patches that introduce
consumers of them.

[..]
> +/* SLIMbus message types. Related to interpretation of message code. */
> +#define SLIM_MSG_MT_CORE			0x0
> +#define SLIM_MSG_MT_DEST_REFERRED_CLASS		0x1
> +#define SLIM_MSG_MT_DEST_REFERRED_USER		0x2
> +#define SLIM_MSG_MT_SRC_REFERRED_CLASS		0x5
> +#define SLIM_MSG_MT_SRC_REFERRED_USER		0x6

These are not currently used, move them to the patch that actually use
them.

> +
> +/* SLIMbus core type Message Codes. */
> +/* Device management messages used by this framework */
> +#define SLIM_MSG_MC_REPORT_PRESENT               0x1
> +#define SLIM_MSG_MC_ASSIGN_LOGICAL_ADDRESS       0x2
> +#define SLIM_MSG_MC_REPORT_ABSENT                0xF

Dito

> +
> +/* Destination type Values */
> +#define SLIM_MSG_DEST_LOGICALADDR	0
> +#define SLIM_MSG_DEST_ENUMADDR		1
> +#define	SLIM_MSG_DEST_BROADCAST		3

Dito

> +
> +/**
> + * struct slim_controller: Controls every instance of SLIMbus
> + *				(similar to 'master' on SPI)
> + *	'Manager device' is responsible for  device management, bandwidth
> + *	allocation, channel setup, and port associations per channel.
> + *	Device management means Logical address assignment/removal based on
> + *	enumeration (report-present, report-absent) if a device.
> + *	Bandwidth allocation is done dynamically by the manager based on active
> + *	channels on the bus, message-bandwidth requests made by slimbus devices.
> + *	Based on current bandwidth usage, manager chooses a frequency to run
> + *	the bus at (in steps of 'clock-gear', 1 through 10, each clock gear
> + *	representing twice the frequency than the previous gear).
> + *	Manager is also responsible for entering (and exiting) low-power-mode
> + *	(known as 'clock pause').
> + *	Manager can do handover of framer if there are multiple framers on the
> + *	bus and a certain usecase warrants using certain framer to avoid keeping
> + *	previous framer being powered-on.
> + *
> + *	Controller here performs duties of the manager device, and 'interface
> + *	device'. Interface device is responsible for monitoring the bus and
> + *	reporting information such as loss-of-synchronization, data
> + *	slot-collision.
> + * @dev: Device interface to this driver
> + * @nr: Board-specific number identifier for this controller/bus
> + * @list: Link with other slimbus controllers
> + * @name: Name for this controller
> + * @min_cg: Minimum clock gear supported by this controller (default value: 1)
> + * @max_cg: Maximum clock gear supported by this controller (default value: 10)
> + * @clkgear: Current clock gear in which this bus is running
> + * @a_framer: Active framer which is clocking the bus managed by this controller
> + * @m_ctrl: Mutex protecting controller data structures

This mutex protects operations on the addrt array, so both name and
documentation can be improved.

> + * @addrt: Logical address table

Consider replacing with a idr, keyed by laddr. If there's actually a
point in having this list...

> + * @num_dev: Number of active slimbus slaves on this bus

This is not so much "number of devices", but rather the length of @addrt.

> + * @wq: Workqueue per controller used to notify devices when they report present
> + * @xfer_msg: Transfer a message on this controller (this can be a broadcast
> + *	control/status message like data channel setup, or a unicast message
> + *	like value element read/write.
> + * @set_laddr: Setup logical address at laddr for the slave with elemental
> + *	address e_addr. Drivers implementing controller will be expected to
> + *	send unicast message to this device with its logical address.
> + * @get_laddr: It is possible that controller needs to set fixed logical
> + *	address table and get_laddr can be used in that case so that controller
> + *	can do this assignment.

Can you describe the use case for get_laddr() a little bit more?

> + */
> +struct slim_controller {
> +	struct device		dev;
> +	unsigned int		nr;
> +	char			name[SLIMBUS_NAME_SIZE];
> +	int			min_cg;
> +	int			max_cg;
> +	int			clkgear;
> +	struct slim_framer	*a_framer;
> +	struct mutex		m_ctrl;
> +	struct slim_addrt	*addrt;
> +	u8			num_dev;
> +	struct workqueue_struct *wq;
> +	int			(*set_laddr)(struct slim_controller *ctrl,
> +					     struct slim_eaddr *ea, u8 laddr);
> +	int			(*get_laddr)(struct slim_controller *ctrl,
> +					     struct slim_eaddr *ea, u8 *laddr);

If nothing else I think this should return the laddr, rather than pass
it back into the referenced u8.

> +};
> +

Regards,
Bjorn
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Thanks for the Review Bjorn,

On 17/10/17 07:23, Bjorn Andersson wrote:
> On Fri 06 Oct 08:51 PDT 2017, srinivas.kandagatla@linaro.org wrote:
> [..]
>> diff --git a/drivers/slimbus/slim-core.c b/drivers/slimbus/slim-core.c
> [..]
>> +/**
>> + * Report callbacks(device_up, device_down) are implemented by slimbus-devices.
>> + * The calls are scheduled into a workqueue to avoid holding up controller
>> + * initialization/tear-down.
>> + */
>> +static void schedule_slim_report(struct slim_controller *ctrl,
>> +				 struct slim_device *sb, bool report)
>> +{
>> +	struct sb_report_wd *sbw;
>> +
>> +	dev_dbg(&ctrl->dev, "report:%d for slave:%s\n", report, sb->name);
> 
> This is the only place where sb->name is used in this driver. If you
> instead invoke dev_*() on &sb->dev you should get prettier output and
> can drop the double storage of the device name.

Makes sense, we could get rid of sb->name storage too.

> 
>> +
>> +	sbw = kmalloc(sizeof(*sbw), GFP_KERNEL);
>> +	if (!sbw)
>> +		return;
>> +
>> +	INIT_WORK(&sbw->wd, slim_report);
>> +	sbw->sbdev = sb;
>> +	sbw->report = report;
>> +	if (!queue_work(ctrl->wq, &sbw->wd)) {
> 
> When a controller is torn down destroy_workqueue() is called after all
> child devices has been unregistered, so this work might be scheduled
> after "sb" is gone, if I get this properly.

I agree, That is possible!
We should probably flush the workqueue before we start removing the clients.

> 
>> +		dev_err(&ctrl->dev, "failed to queue report:%d slave:%s\n",
>> +				    report, sb->name);
>> +		kfree(sbw);
>> +	}
>> +}
>> +
>> +static int slim_device_probe(struct device *dev)
>> +{
>> +	struct slim_device	*sbdev;
>> +	struct slim_driver	*sbdrv;
>> +	int status = 0;
>> +
>> +	sbdev = to_slim_device(dev);
>> +	sbdrv = to_slim_driver(dev->driver);
>> +
>> +	sbdev->driver = sbdrv;
>> +
>> +	if (sbdrv->probe)
>> +		status = sbdrv->probe(sbdev);
> 
> So a driver can have a probe() and device_up() or just any one of them?
> 
> And probe() is called when the controller enumerates all devices
> mentioned in DT and then device_up() is called at that point in time and
> when it's advertised on the bus?
> 
> Is there a reason for this split model?
> 
yes, Some of the devices need to be powered up before they become 
usable, so probe is used to do the initial power up of the device.


>> +
>> +	if (status)
>> +		sbdev->driver = NULL;
>> +	else if (sbdrv->device_up)
>> +		schedule_slim_report(sbdev->ctrl, sbdev, true);
>> +
>> +	return status;
>> +}
>> +
>> +static int slim_device_remove(struct device *dev)
>> +{
>> +	struct slim_device *sbdev;
>> +	struct slim_driver *sbdrv;
>> +	int status = 0;
>> +
>> +	sbdev = to_slim_device(dev);
>> +	if (!dev->driver)
>> +		return 0;
>> +
>> +	sbdrv = to_slim_driver(dev->driver);
>> +	if (sbdrv->remove)
>> +		status = sbdrv->remove(sbdev);
>> +
>> +	mutex_lock(&sbdev->report_lock);
>> +	sbdev->notified = false;
>> +	if (status == 0)
>> +		sbdev->driver = NULL;
>> +	mutex_unlock(&sbdev->report_lock);
>> +	return status;
> 
> device_unregister() will call device_del() which will end up in
> __device_release_driver() which will call this function. Upon returning
> from this function the core expect the bus to have cleaned up after the
> dev (normally by calling drv->remove(dev)).
> 
> It will completely ignore the return value and continue tearing down the
> rest of the core resources, e.g. three lines down it will
> devres_release_all().
> 
> 
> So you have the option of sleeping, while waiting for stuff to be
> aborted/finished and then you need to clean things up.
> 
> The slim_device object itself will stick around until all references are
> dropped though.

So you are suggesting that we make slim_driver remove not return anything?

> 
>> +}
>> +
>> +struct bus_type slimbus_type = {
>> +	.name		= "slimbus",
>> +	.match		= slim_device_match,
>> +	.probe		= slim_device_probe,
>> +	.remove		= slim_device_remove,
>> +};
>> +EXPORT_SYMBOL_GPL(slimbus_type);
>> +
>> +/**
>> + * slim_driver_register: Client driver registration with slimbus
>> + * @drv:Client driver to be associated with client-device.
>> + * @owner: owning module/driver
>> + * This API will register the client driver with the slimbus
>> + * It is called from the driver's module-init function.
>> + */
>> +int __slim_driver_register(struct slim_driver *drv, struct module *owner)
>> +{
>> +	drv->driver.bus = &slimbus_type;
>> +	drv->driver.owner = owner;
>> +	return driver_register(&drv->driver);
>> +}
>> +EXPORT_SYMBOL_GPL(__slim_driver_register);
>> +
>> +/**
>> + * slim_driver_unregister: Undo effect of slim_driver_register
>> + * @drv: Client driver to be unregistered
>> + */
>> +void slim_driver_unregister(struct slim_driver *drv)
>> +{
>> +	if (drv)
> 
> A driver invoking slim_driver_unregister(NULL) is broken, drop this
> check and let it oops on the dereference instead.

Yep.

> 
>> +		driver_unregister(&drv->driver);
>> +}
>> +EXPORT_SYMBOL_GPL(slim_driver_unregister);
>> +
>> +static struct slim_controller *slim_ctrl_get(struct slim_controller *ctrl)
>> +{
>> +	if (!ctrl || !get_device(&ctrl->dev))
> 
> ctrl can't be NULL here. In all code paths leading here it's
> dereferenced multiple times already.

I agree.

> 
>> +		return NULL;
>> +
>> +	return ctrl;
>> +}
>> +
>> +static void slim_ctrl_put(struct slim_controller *ctrl)
>> +{
>> +	if (ctrl)
>> +		put_device(&ctrl->dev);
>> +}
>> +
>> +static void slim_dev_release(struct device *dev)
>> +{
>> +	struct slim_device *sbdev = to_slim_device(dev);
>> +
>> +	slim_ctrl_put(sbdev->ctrl);
> 
> As far as I can see there's no case where sbdev->ctrl will ever be NULL,
> so yo can just replace this with
> 	put_device(&ctrl->dev);
> 
> And drop slim_ctrl_put().


Yes..

> 
>> +	kfree(sbdev->name);
>> +	kfree(sbdev);
>> +}
>> +
>> +static int slim_add_device(struct slim_controller *ctrl,
>> +			   struct slim_device *sbdev)
>> +{
>> +	sbdev->dev.bus = &slimbus_type;
>> +	sbdev->dev.parent = &ctrl->dev;
>> +	sbdev->dev.release = slim_dev_release;
>> +	sbdev->dev.driver = NULL;
>> +	sbdev->ctrl = ctrl;
>> +
>> +	slim_ctrl_get(ctrl);
> 
> Unfolding slim_ctrl_get(), with ctrl != NULL, gives us a container_of(),
> so this can't fail. Which is good because then an error check would have
> been nice.
> 
> But it also means that you can replace this with just:
> 	get_device(&ctrl->dev);
> 
> And drop slim_ctrl_get()
> 

ya.

>> +	sbdev->name = kasprintf(GFP_KERNEL, "%x:%x:%x:%x",
>> +					sbdev->e_addr.manf_id,
>> +					sbdev->e_addr.prod_code,
>> +					sbdev->e_addr.dev_index,
>> +					sbdev->e_addr.instance);
>> +	if (!sbdev->name)
>> +		return -ENOMEM;
>> +
>> +	dev_set_name(&sbdev->dev, "%s", sbdev->name);
> 
> This will create another copy of the same string and as noted above
> there seems to be only one consumer, which could be switched over. So
> you can drop above kasprintf() and just use dev_set_name to format the
> name.
> 
> An added benefit is that you're not leaking the device reference from
> slim_ctrl_get() on the line before.

I agree, will fix this in next version.

> 
>> +	mutex_init(&sbdev->report_lock);
>> +
>> +	/* probe slave on this controller */
>> +	return device_register(&sbdev->dev);
>> +}
>> +
>> +/* Helper to get hex Manufacturer ID and Product id from compatible */
>> +static unsigned long str2hex(unsigned char *str)
> 
> The caller of this passes char *, so you can drop the unsigned. And add
> "const" while you're at it.

I will be removing this function in next version, replacing it with 
kstrtoul()

> 
>> +{
>> +	int value = 0;
>> +
>> +	while (*str) {
>> +		char c = *str++;
>> +
>> +		value = value << 4;
>> +		if (c >= '0' && c <= '9')
>> +			value |= (c - '0');
>> +		if (c >= 'a' && c <= 'f')
>> +			value |= (c - 'a' + 10);
> 
> At the cost of one more check here you can drop the line in the
> documentation about this only working for lower-case hex digits.
> 
>> +
>> +	}
>> +
>> +	return value;
>> +}
>> +
>> +/* OF helpers for SLIMbus */
>> +static void of_register_slim_devices(struct slim_controller *ctrl)
>> +{
>> +	struct device *dev = &ctrl->dev;
>> +	struct device_node *node;
>> +
>> +	if (!ctrl->dev.of_node)
>> +		return;
>> +
>> +	for_each_child_of_node(ctrl->dev.of_node, node) {
>> +		struct slim_device *slim;
>> +		const char *compat = NULL;
>> +		char *p, *tok;
>> +		int reg[2], ret;
>> +
>> +		slim = kzalloc(sizeof(*slim), GFP_KERNEL);
> 
> This is leaked in several places below.
> 
>> +		if (!slim)
>> +			continue;
>> +
>> +		slim->dev.of_node = of_node_get(node);
> 
> Dito.
> 
>> +
>> +		compat = of_get_property(node, "compatible", NULL);
>> +		if (!compat)
>> +			continue;
>> +
>> +		p = kasprintf(GFP_KERNEL, "%s", compat + strlen("slim"));
> 
> Allocating a new string using string formatting based on an offset from
> a string we don't know the size of, just to tokenize it does not seem
> like the most efficient (nor safe) way of doing this.
> 
> 
> How about:
> 		ret = sscanf(compat, "slim%x,%x", &manf_id, &prod_code);
> 		if (ret != 2)
> 			error();
> 
Looks much better!


>> +
>> +		tok = strsep(&p, ",");
>> +		if (!tok) {
>> +			dev_err(dev, "No valid Manufacturer ID found\n");
>> +			kfree(p);
>> +			continue;
>> +		}
>> +		slim->e_addr.manf_id = str2hex(tok);
>> +
>> +		tok = strsep(&p, ",");
>> +		if (!tok) {
>> +			dev_err(dev, "No valid Product ID found\n");
>> +			kfree(p);
>> +			continue;
>> +		}
>> +		slim->e_addr.prod_code = str2hex(tok);
>> +		kfree(p);
>> +
>> +		ret = of_property_read_u32_array(node, "reg", reg, 2);
>> +		if (ret) {
>> +			dev_err(dev, "Device and Instance id not found:%d\n",
>> +				ret);
>> +			continue;
>> +		}
>> +		slim->e_addr.dev_index = reg[0];
>> +		slim->e_addr.instance = reg[1];
>> +
>> +		ret = slim_add_device(ctrl, slim);
>> +		if (ret)
>> +			dev_err(dev, "of_slim device register err:%d\n", ret);
> 
> Cleanup if this fails.
Yes, we are leaking memory here, will fix this in next version.
> 
>> +	}
>> +}
>> +
>> +/**
>> + * slim_register_controller: Controller bring-up and registration.
>> + * @ctrl: Controller to be registered.
>> + * A controller is registered with the framework using this API.
>> + * If devices on a controller were registered before controller,
>> + * this will make sure that they get probed when controller is up
>> + */
>> +int slim_register_controller(struct slim_controller *ctrl)
>> +{
>> +	int id, ret = 0;
>> +
>> +	mutex_lock(&slim_lock);
>> +	id = idr_alloc(&ctrl_idr, ctrl, ctrl->nr, -1, GFP_KERNEL);
> 
> The purpose of ctrl_idr is to generate unique ids for the name and to
> check that slim_del_controller() is only called on valid
> slim_controllers.
> 
> The latter is okay to just expect the controller drivers to do right and
> the prior is better done with an ida.
> 

I agree, IDA seems to be better fit here.

> 
> Also, the lower boundary should be 0, not ctrl->nr.
> 
>> +	mutex_unlock(&slim_lock);
>> +
>> +	if (id < 0)
>> +		return id;
>> +
>> +	ctrl->nr = id;
>> +
>> +	dev_set_name(&ctrl->dev, "sb-%d", ctrl->nr);
> 
> This name is used in a lot of debug prints, can we do better?
> 
In some of the previous discussions with Vinod, it was suggested that 
slim_register_controller should not create an additional device here, 
which is redundant to the actual controller device itself.

So this name would actually come from the controller driver in next 
version of patches.

>> +	ctrl->num_dev = 0;
>> +
>> +	if (!ctrl->min_cg)
>> +		ctrl->min_cg = SLIM_MIN_CLK_GEAR;
>> +	if (!ctrl->max_cg)
>> +		ctrl->max_cg = SLIM_MAX_CLK_GEAR;
>> +
>> +	mutex_init(&ctrl->m_ctrl);
>> +	ret = device_register(&ctrl->dev);
>> +	if (ret)
>> +		goto dev_reg_failed;
>> +
>> +	dev_dbg(&ctrl->dev, "Bus [%s] registered:dev:%p\n",
>> +		ctrl->name, &ctrl->dev);
> 
> This is the only place ctrl->name is used. Perhaps it would make more
> sense to base the dev_name off this string, to make all these dev_*()
> more useful.

Agreed.
> 
>> +
>> +	ctrl->wq = create_singlethread_workqueue(dev_name(&ctrl->dev));
>> +	if (!ctrl->wq)
>> +		goto err_workq_failed;
>> +
>> +	of_register_slim_devices(ctrl);
>> +
>> +	return 0;
>> +
>> +err_workq_failed:
>> +	device_unregister(&ctrl->dev);
>> +dev_reg_failed:
>> +	mutex_lock(&slim_lock);
>> +	idr_remove(&ctrl_idr, ctrl->nr);
>> +	mutex_unlock(&slim_lock);
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(slim_register_controller);
>> +
>> +/* slim_remove_device: Remove the effect of slim_add_device() */
>> +static void slim_remove_device(struct slim_device *sbdev)
>> +{
>> +	device_unregister(&sbdev->dev);
>> +}
>> +
>> +static int slim_ctrl_remove_device(struct device *dev, void *null)
>> +{
>> +	slim_remove_device(to_slim_device(dev));
>> +	return 0;
>> +}
>> +
>> +/**
>> + * slim_del_controller: Controller tear-down.
>> + * @ctrl: Controller to tear-down.
>> + */
>> +int slim_del_controller(struct slim_controller *ctrl)
> 
> This is the opposite of slim_register_controller() so should it perhaps
> be called slim_unregister_controller() ?

makes sense..
> 
>> +{
>> +	struct slim_controller *found;
>> +
>> +	/* First make sure that this bus was added */
>> +	mutex_lock(&slim_lock);
>> +	found = idr_find(&ctrl_idr, ctrl->nr);
>> +	mutex_unlock(&slim_lock);
>> +	if (found != ctrl)
>> +		return -EINVAL;
> 
> Just rely on the caller doing the right thing and just
> 	ida_remove(&ctrl_ida, ctrl->nr);

Moving to ida is best

> 
>> +
>> +	/* Remove all clients */
>> +	device_for_each_child(&ctrl->dev, NULL, slim_ctrl_remove_device);
>> +
> 
> As stated above there might be work items left in flight here, after the
> slim_devices are released.
> 
We should flush the workqueue before we remove the devices.

>> 
>> +	destroy_workqueue(ctrl->wq);
>> +
>> +	/* free bus id */
>> +	mutex_lock(&slim_lock);
>> +	idr_remove(&ctrl_idr, ctrl->nr);
>> +	mutex_unlock(&slim_lock);
>> +
>> +	device_unregister(&ctrl->dev);
>> +	return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(slim_del_controller);
> [..]
>> +/**
>> + * slim_query_device: Query and get handle to a device.
>> + * @ctrl: Controller on which this device will be added/queried
>> + * @e_addr: Enumeration address of the device to be queried
>> + * Returns pointer to a device if it has already reported. Creates a new
>> + * device and returns pointer to it if the device has not yet enumerated.
>> + */
>> +struct slim_device *slim_query_device(struct slim_controller *ctrl,
>> +				      struct slim_eaddr *e_addr)
>> +{
>> +	struct device *dev;
>> +	struct slim_device *slim = NULL;
> 
> This will be written before read, so please don't initialize.
> 
yep.

>> +
>> +	dev = device_find_child(&ctrl->dev, e_addr, slim_match_dev);
>> +	if (dev) {
>> +		slim = to_slim_device(dev);
>> +		return slim;
>> +	}
>> +
>> +	slim = kzalloc(sizeof(struct slim_device), GFP_KERNEL);
>> +	if (IS_ERR(slim))
> 
> !slim
yep.

> 
>> +		return NULL;
>> +
>> +	slim->e_addr = *e_addr;
>> +	if (slim_add_device(ctrl, slim) != 0) {
> 
> The idiomatic way is:
> 
> ret = fn();
> if (ret) {
> 	failure...
> }
> 
okay
>> +		kfree(slim);
>> +		return NULL;
>> +	}
>> +	return slim;
>> +}
>> +EXPORT_SYMBOL_GPL(slim_query_device);
>> +
>> +static int ctrl_getaddr_entry(struct slim_controller *ctrl,
>> +			      struct slim_eaddr *eaddr, u8 *entry)
>> +{
>> +	int i;
>> +
>> +	for (i = 0; i < ctrl->num_dev; i++) {
>> +		if (ctrl->addrt[i].valid &&
>> +		    slim_eaddr_equal(&ctrl->addrt[i].eaddr, eaddr)) {
>> +			*entry = i;
> 
> i will be >= 0, so it can easily be distinguished from -ENXIO. So you
> could return that directly instead of passing "i" as a reference and to
> get the value.
> 
> On the other hand the return value is only used as an offset in addrt[]
> to read out addrt[i].laddr, so perhaps you should just return that
> instead (as an int).
> 
sounds sensible!

>> +			return 0;
>> +		}
>> +	}
>> +	return -ENXIO;
>> +}
>> +
>> +/**
>> + * slim_assign_laddr: Assign logical address to a device enumerated.
> 
> So I presume this will either report a new (not seen before) e_addr
> which should cause a new device to be spawned (although it might be
> already mentioned in DT) or it might be called for an existing device to
> update the logical address.
> 
> Can you describe when the latter is the case? Or is this a side effect
> of the code, rather than slimbus?

If this function is called for an existing device with logical address, 
it would give the same logical address, if it finds a vaild one in the 
table.
Other case is when it does not find a valid on then a new address is 
assigned depending on the valid flag passed to the function.
This case is more to do with the Qualcomm B family Slim controller, 
where linux side can not assign logical address, As DSP would only be 
able to assign this address.

>> + * @ctrl: Controller with which device is enumerated.
>> + * @e_addr: Enumeration address of the device.
>> + * @laddr: Return logical address (if valid flag is false)
>> + * @valid: true if laddr holds a valid address that controller wants to
>> + *	set for this enumeration address. Otherwise framework sets index into
>> + *	address table as logical address.
> 
> How do you ensure this laddr is unique?
Its index into a table which is based on unique enumeration address.

> 
>> + * Called by controller in response to REPORT_PRESENT. Framework will assign
>> + * a logical address to this enumeration address.
>> + * Function returns -EXFULL to indicate that all logical addresses are already
>> + * taken.
>> + */
>> +int slim_assign_laddr(struct slim_controller *ctrl, struct slim_eaddr *e_addr,
>> +		      u8 *laddr, bool valid)
>> +{
>> +	int ret;
>> +	u8 i = 0;
>> +	bool exists = false;
>> +	struct slim_device *slim;
>> +	struct slim_addrt *temp;
>> +
>> +	mutex_lock(&ctrl->m_ctrl);
>> +	/* already assigned */
>> +	if (ctrl_getaddr_entry(ctrl, e_addr, &i) == 0) {
> 
> So I presume this updates an existing e_addr -> laddr mapping. But this
> should imply that there is an associated slim_device with this e_addr
> and laddr. Shouldn't said slim_device have its laddr updated then?

If we find a vaild an matching entry in the list, we assume that the 
slim device is already aware of this laddr.


> 
>> +		*laddr = ctrl->addrt[i].laddr;
>> +		exists = true;
>> +	} else {
>> +		if (ctrl->num_dev >= (SLIM_LA_MANAGER - 1)) {
>> +			ret = -EXFULL;
>> +			goto ret_assigned_laddr;
>> +		}
>> +		for (i = 0; i < ctrl->num_dev; i++) {
>> +			if (ctrl->addrt[i].valid == false)
>> +				break;
>> +		}
>> +		if (i == ctrl->num_dev) {
>> +			temp = krealloc(ctrl->addrt,
>> +					(ctrl->num_dev + 1) *
>> +					sizeof(struct slim_addrt),
>> +					GFP_KERNEL);
>> +			if (!temp) {
>> +				ret = -ENOMEM;
>> +				goto ret_assigned_laddr;
>> +			}
>> +			ctrl->addrt = temp;
>> +			ctrl->num_dev++;
>> +		}
> 
> This seems better handled by a list than an array that we realloc. But
> better yet, this array seems to mirror the list of registered devices.
> 
> So why doesn't this function just try to resolve the slim_device with
> e_addr and if not allocate a new slim_device with a free laddr. Using an
> ida to keep track of used logical addresses would make this much
> cleaner.
> 
> Or a idr keyed by the laddr, it would still be O(n) to scan based on
> e_addr, but this logic as well as lookups by laddr would be cleaner.
> 
I will give this a try before sending next version and see how it looks!

>> +		ctrl->addrt[i].eaddr = *e_addr;
>> +		ctrl->addrt[i].valid = true;
>> +
>> +		/* Preferred address is index into table */
>> +		if (!valid)
>> +			*laddr = i;
> 
> Is this laddr available?
this is the new index or first instance of invalid entry in the table, 
so it should be available.
> 
>> +	}
>> +
>> +	ret = ctrl->set_laddr(ctrl, &ctrl->addrt[i].eaddr, *laddr);
>> +	if (ret) {
>> +		ctrl->addrt[i].valid = false;
>> +		goto ret_assigned_laddr;
>> +	}
>> +	ctrl->addrt[i].laddr = *laddr;
>> +
>> +ret_assigned_laddr:
>> +	mutex_unlock(&ctrl->m_ctrl);
>> +	if (exists || ret)
>> +		return ret;
>> +
>> +	dev_info(&ctrl->dev, "setting slimbus l-addr:%x, ea:%x,%x,%x,%x\n",
>> +		*laddr, e_addr->manf_id, e_addr->prod_code,
>> +		e_addr->dev_index, e_addr->instance);
>> +
>> +	/**
>> +	 * Add this device to list of devices on this controller if it's
>> +	 * not already present
>> +	 */
>> +	slim = slim_query_device(ctrl, e_addr);
>> +	if (!slim) {
>> +		ret = -ENODEV;
>> +	} else {
>> +		struct slim_driver *sbdrv;
>> +
>> +		slim->laddr = *laddr;
>> +		mutex_lock(&slim->report_lock);
>> +		slim->reported = true;
>> +		if (slim->dev.driver) {
>> +			sbdrv = to_slim_driver(slim->dev.driver);
>> +			if (sbdrv->device_up)
>> +				schedule_slim_report(ctrl, slim, true);
>> +		}
>> +		mutex_unlock(&slim->report_lock);
> 
> I can't help feeling that this is the one and only point where you
> should call probe() on the slim_device. Are there some funky
> dependencies or protocol issues that makes this infeasible?

The reason probe is called earlier because the slim device needs 
power-up or reset sequence to make it discoverable on the bus.

> 
>> +	}
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(slim_assign_laddr);
>> +
>> +/**
>> + * slim_get_logical_addr: Return the logical address of a slimbus device.
>> + * @sb: client handle requesting the address.
>> + * @e_addr: Enumeration address of the device.
>> + * @laddr: output buffer to store the address
>> + * context: can sleep
>> + * -EINVAL is returned in case of invalid parameters, and -ENXIO is returned if
>> + *  the device with this enumeration address is not found.
>> + */
>> +int slim_get_logical_addr(struct slim_device *sb, struct slim_eaddr *e_addr,
>> +			  u8 *laddr)
> 
> In what case would e_addr != sb->e_addr and why can't this function just
> be return sb->laddr?
> 
I don't think e_addr and sb->eaddr should be different in this case.

In usecase like B family Qualcomm SOCs, where linux cannot assign 
logical address, It needs to get logical address from ADSP and then use 
that. Current model of get_logical_addr provides abstraction so that 
this ADSP communication to get logical addr is hidden from client.


>> +{
>> +	int ret;
>> +	u8 entry;
>> +	struct slim_controller *ctrl = sb->ctrl;
>> +
>> +	if (!ctrl || !laddr || !e_addr)
>> +		return -EINVAL;
>> +
>> +	mutex_lock(&ctrl->m_ctrl);
>> +	ret = ctrl_getaddr_entry(ctrl, e_addr, &entry);
>> +	if (!ret)
>> +		*laddr = ctrl->addrt[entry].laddr;
>> +	mutex_unlock(&ctrl->m_ctrl);
>> +
>> +	if (ret == -ENXIO && ctrl->get_laddr) {
>> +		ret = ctrl->get_laddr(ctrl, e_addr, laddr);
>> +		if (!ret)
>> +			ret = slim_assign_laddr(ctrl, e_addr, laddr, true);
>> +	}
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(slim_get_logical_addr);
> [..]
>> +
>> +MODULE_LICENSE("GPL v2");
>> +MODULE_VERSION("0.1");
> 
> Who will ever update this version number? It's probably better to just
> omit it.
>
Yep.

>> +MODULE_DESCRIPTION("Slimbus module");
> 
> Rather than "Slimbus module", this is actually the "Slimbus core".
> 
Yep.
>> diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
> [..]
>> +extern struct bus_type slimbus_type;
> 
> The device struct has a "struct device_type *type", which causes this
> name to be confusing. Please rename it slimbus_bus instead.
> 
> Why does this bus_type have to be known to the world?
May be not. can be removed.
> 
>> +
>> +/* Standard values per SLIMbus spec needed by controllers and devices */
>> +#define SLIM_CL_PER_SUPERFRAME		6144
>> +#define SLIM_CL_PER_SUPERFRAME_DIV8	(SLIM_CL_PER_SUPERFRAME >> 3)
>> +#define SLIM_MAX_CLK_GEAR		10
>> +#define SLIM_MIN_CLK_GEAR		1
>> +#define SLIM_CL_PER_SL			4
>> +#define SLIM_SL_PER_SUPERFRAME		(SLIM_CL_PER_SUPERFRAME >> 2)
>> +#define SLIM_FRM_SLOTS_PER_SUPERFRAME	16
>> +#define SLIM_GDE_SLOTS_PER_SUPERFRAME	2
> 
> Keep the min/max here and move the rest to the patches that introduce
> consumers of them.

makes sense!

> 
> [..]
>> +/* SLIMbus message types. Related to interpretation of message code. */
>> +#define SLIM_MSG_MT_CORE			0x0
>> +#define SLIM_MSG_MT_DEST_REFERRED_CLASS		0x1
>> +#define SLIM_MSG_MT_DEST_REFERRED_USER		0x2
>> +#define SLIM_MSG_MT_SRC_REFERRED_CLASS		0x5
>> +#define SLIM_MSG_MT_SRC_REFERRED_USER		0x6
> 
> These are not currently used, move them to the patch that actually use
> them.
> 
>> +
>> +/* SLIMbus core type Message Codes. */
>> +/* Device management messages used by this framework */
>> +#define SLIM_MSG_MC_REPORT_PRESENT               0x1
>> +#define SLIM_MSG_MC_ASSIGN_LOGICAL_ADDRESS       0x2
>> +#define SLIM_MSG_MC_REPORT_ABSENT                0xF
> 
> Dito
> 
>> +
>> +/* Destination type Values */
>> +#define SLIM_MSG_DEST_LOGICALADDR	0
>> +#define SLIM_MSG_DEST_ENUMADDR		1
>> +#define	SLIM_MSG_DEST_BROADCAST		3
> 
> Dito

will do it in next version.


> 
>> +
>> +/**
>> + * struct slim_controller: Controls every instance of SLIMbus
>> + *				(similar to 'master' on SPI)
>> + *	'Manager device' is responsible for  device management, bandwidth
>> + *	allocation, channel setup, and port associations per channel.
>> + *	Device management means Logical address assignment/removal based on
>> + *	enumeration (report-present, report-absent) if a device.
>> + *	Bandwidth allocation is done dynamically by the manager based on active
>> + *	channels on the bus, message-bandwidth requests made by slimbus devices.
>> + *	Based on current bandwidth usage, manager chooses a frequency to run
>> + *	the bus at (in steps of 'clock-gear', 1 through 10, each clock gear
>> + *	representing twice the frequency than the previous gear).
>> + *	Manager is also responsible for entering (and exiting) low-power-mode
>> + *	(known as 'clock pause').
>> + *	Manager can do handover of framer if there are multiple framers on the
>> + *	bus and a certain usecase warrants using certain framer to avoid keeping
>> + *	previous framer being powered-on.
>> + *
>> + *	Controller here performs duties of the manager device, and 'interface
>> + *	device'. Interface device is responsible for monitoring the bus and
>> + *	reporting information such as loss-of-synchronization, data
>> + *	slot-collision.
>> + * @dev: Device interface to this driver
>> + * @nr: Board-specific number identifier for this controller/bus
>> + * @list: Link with other slimbus controllers
>> + * @name: Name for this controller
>> + * @min_cg: Minimum clock gear supported by this controller (default value: 1)
>> + * @max_cg: Maximum clock gear supported by this controller (default value: 10)
>> + * @clkgear: Current clock gear in which this bus is running
>> + * @a_framer: Active framer which is clocking the bus managed by this controller
>> + * @m_ctrl: Mutex protecting controller data structures
> 
> This mutex protects operations on the addrt array, so both name and
> documentation can be improved.
Agreed, will address this in next version.

> 
>> + * @addrt: Logical address table
> 
> Consider replacing with a idr, keyed by laddr. If there's actually a
> point in having this list...
> 
>> + * @num_dev: Number of active slimbus slaves on this bus
> 
> This is not so much "number of devices", but rather the length of @addrt.

lenght of addrt might be more than active devices as some of the entries 
in addrt are not valid after the device goes down.


> 
>> + * @wq: Workqueue per controller used to notify devices when they report present
>> + * @xfer_msg: Transfer a message on this controller (this can be a broadcast
>> + *	control/status message like data channel setup, or a unicast message
>> + *	like value element read/write.
>> + * @set_laddr: Setup logical address at laddr for the slave with elemental
>> + *	address e_addr. Drivers implementing controller will be expected to
>> + *	send unicast message to this device with its logical address.
>> + * @get_laddr: It is possible that controller needs to set fixed logical
>> + *	address table and get_laddr can be used in that case so that controller
>> + *	can do this assignment.
> 
> Can you describe the use case for get_laddr() a little bit more?

Usecase is  for  B family Qualcomm SOCs, where linux cannot assign 
logical address, It needs to get logical address from ADSP and then use 
that. Current model of get_logical_addr provides abstraction so that 
this ADSP communication to get logical addr is hidden from client.

> 
>> + */
>> +struct slim_controller {
>> +	struct device		dev;
>> +	unsigned int		nr;
>> +	char			name[SLIMBUS_NAME_SIZE];
>> +	int			min_cg;
>> +	int			max_cg;
>> +	int			clkgear;
>> +	struct slim_framer	*a_framer;
>> +	struct mutex		m_ctrl;
>> +	struct slim_addrt	*addrt;
>> +	u8			num_dev;
>> +	struct workqueue_struct *wq;
>> +	int			(*set_laddr)(struct slim_controller *ctrl,
>> +					     struct slim_eaddr *ea, u8 laddr);
>> +	int			(*get_laddr)(struct slim_controller *ctrl,
>> +					     struct slim_eaddr *ea, u8 *laddr);
> 
> If nothing else I think this should return the laddr, rather than pass
> it back into the referenced u8.

I will give it a go and see how it fits with every thing around it.

> 
>> +};
>> +
> 
> Regards,
> Bjorn
> 
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On Fri, Oct 06, 2017 at 05:51:30PM +0200, srinivas.kandagatla@linaro.org wrote:

> ---
>  Documentation/devicetree/bindings/slimbus/bus.txt |  57 ++
>  Documentation/slimbus/summary                     | 109 ++++

This is a 40k patch which is a bit offputting for review.  Splitting the
docs out would help this a bit.

> +static int slim_boot_child(struct device *dev, void *unused)
> +{
> +	struct slim_driver *sbdrv;
> +	struct slim_device *sbdev = to_slim_device(dev);
> +
> +	if (sbdev && sbdev->dev.driver) {
> +		sbdrv = to_slim_driver(sbdev->dev.driver);
> +		if (sbdrv->boot_device)
> +			sbdrv->boot_device(sbdev);
> +	}
> +	return 0;
> +}

We silently don't boot a device if it hasn't got a driver - is that the
right thing?  It feels like the silencing should be in the calling
function.

> +ret_assigned_laddr:
> +	mutex_unlock(&ctrl->m_ctrl);
> +	if (exists || ret)
> +		return ret;
> +
> +	dev_info(&ctrl->dev, "setting slimbus l-addr:%x, ea:%x,%x,%x,%x\n",
> +		*laddr, e_addr->manf_id, e_addr->prod_code,
> +		e_addr->dev_index, e_addr->instance);

dev_dbg()?

On 10/06, srinivas.kandagatla@linaro.org wrote:
> +
> +SLIMbus example for Qualcomm's slimbus manager component:
> +
> +	slim@28080000 {
> +		compatible = "qcom,slim-msm";
> +		reg = <0x28080000 0x2000>,
> +		interrupts = <0 33 0>;
> +		clocks = <&lcc SLIMBUS_SRC>, <&lcc AUDIO_SLIMBUS_CLK>;
> +		clock-names = "iface_clk", "core_clk";

Please remove "_clk" from here.

> +		#address-cells = <2>;
> +		#size-cells = <0>;
> +
> +		codec: wcd9310@1{
> +			compatible = "slim217,60"";
> +			reg = <1 0>;
> +		};
> +	};

On Wed 18 Oct 09:38 PDT 2017, Srinivas Kandagatla wrote:
> On 17/10/17 07:23, Bjorn Andersson wrote:
> > On Fri 06 Oct 08:51 PDT 2017, srinivas.kandagatla@linaro.org wrote:
[..]
> > > +static int slim_device_remove(struct device *dev)
> > > +{
> > > +	struct slim_device *sbdev;
> > > +	struct slim_driver *sbdrv;
> > > +	int status = 0;
> > > +
> > > +	sbdev = to_slim_device(dev);
> > > +	if (!dev->driver)
> > > +		return 0;
> > > +
> > > +	sbdrv = to_slim_driver(dev->driver);
> > > +	if (sbdrv->remove)
> > > +		status = sbdrv->remove(sbdev);
> > > +
> > > +	mutex_lock(&sbdev->report_lock);
> > > +	sbdev->notified = false;
> > > +	if (status == 0)
> > > +		sbdev->driver = NULL;
> > > +	mutex_unlock(&sbdev->report_lock);
> > > +	return status;
> > 
> > device_unregister() will call device_del() which will end up in
> > __device_release_driver() which will call this function. Upon returning
> > from this function the core expect the bus to have cleaned up after the
> > dev (normally by calling drv->remove(dev)).
> > 
> > It will completely ignore the return value and continue tearing down the
> > rest of the core resources, e.g. three lines down it will
> > devres_release_all().
> > 
> > 
> > So you have the option of sleeping, while waiting for stuff to be
> > aborted/finished and then you need to clean things up.
> > 
> > The slim_device object itself will stick around until all references are
> > dropped though.
> 
> So you are suggesting that we make slim_driver remove not return anything?
> 

Yes.

Having the opportunity of failing remove() causes driver writers to
expect that they can fail, with the result of things not being torn
down properly.

Note that right after remove() returns devm_* resources will be
released, so anything that is not torn down and for some reason later
access allocated resources would cause issues.

Regards,
Bjorn
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