[v4,1/3] mfd: add support for Diolan DLN-2 devices
diff mbox

Message ID 1410290686-6680-2-git-send-email-octavian.purdila@intel.com
State Not Applicable
Headers show

Commit Message

Octavian Purdila Sept. 9, 2014, 7:24 p.m. UTC
This patch implements the USB part of the Diolan USB-I2C/SPI/GPIO
Master Adapter DLN-2. Details about the device can be found here:

https://www.diolan.com/i2c/i2c_interface.html.

Information about the USB protocol can be found in the Programmer's
Reference Manual [1], see section 1.7.

Because the hardware has a single transmit endpoint and a single
receive endpoint the communication between the various DLN2 drivers
and the hardware will be muxed/demuxed by this driver.

Each DLN2 module will be identified by the handle field within the DLN2
message header. If a DLN2 module issues multiple commands in parallel
they will be identified by the echo counter field in the message header.

The DLN2 modules can use the dln2_transfer() function to issue a
command and wait for its response. They can also register a callback
that is going to be called when a specific event id is generated by
the device (e.g. GPIO interrupts). The device uses handle 0 for
sending events.

[1] https://www.diolan.com/downloads/dln-api-manual.pdf

Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
---
 drivers/mfd/Kconfig      |   9 +
 drivers/mfd/Makefile     |   1 +
 drivers/mfd/dln2.c       | 681 +++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/mfd/dln2.h |  71 +++++
 4 files changed, 762 insertions(+)
 create mode 100644 drivers/mfd/dln2.c
 create mode 100644 include/linux/mfd/dln2.h

Comments

Lee Jones Sept. 16, 2014, 11:21 p.m. UTC | #1
On Tue, 09 Sep 2014, Octavian Purdila wrote:

> This patch implements the USB part of the Diolan USB-I2C/SPI/GPIO
> Master Adapter DLN-2. Details about the device can be found here:
> 
> https://www.diolan.com/i2c/i2c_interface.html.
> 
> Information about the USB protocol can be found in the Programmer's
> Reference Manual [1], see section 1.7.

This driver really needs a USB Ack before I can accept it.

> Because the hardware has a single transmit endpoint and a single
> receive endpoint the communication between the various DLN2 drivers
> and the hardware will be muxed/demuxed by this driver.
> 
> Each DLN2 module will be identified by the handle field within the DLN2
> message header. If a DLN2 module issues multiple commands in parallel
> they will be identified by the echo counter field in the message header.
> 
> The DLN2 modules can use the dln2_transfer() function to issue a
> command and wait for its response. They can also register a callback
> that is going to be called when a specific event id is generated by
> the device (e.g. GPIO interrupts). The device uses handle 0 for
> sending events.
> 
> [1] https://www.diolan.com/downloads/dln-api-manual.pdf
> 
> Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
> ---
>  drivers/mfd/Kconfig      |   9 +
>  drivers/mfd/Makefile     |   1 +
>  drivers/mfd/dln2.c       | 681 +++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/mfd/dln2.h |  71 +++++
>  4 files changed, 762 insertions(+)
>  create mode 100644 drivers/mfd/dln2.c
>  create mode 100644 include/linux/mfd/dln2.h

[...]

> diff --git a/drivers/mfd/dln2.c b/drivers/mfd/dln2.c
> new file mode 100644
> index 0000000..b551b5e
> --- /dev/null
> +++ b/drivers/mfd/dln2.c
> @@ -0,0 +1,681 @@
> +/*
> + * Driver for the Diolan DLN-2 USB adapter
> + *
> + * Copyright (c) 2014 Intel Corporation
> + *
> + * Derived from:
> + *  i2c-diolan-u2c.c
> + *  Copyright (c) 2010-2011 Ericsson AB
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation, version 2.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/errno.h>

What are you using this for?

> +#include <linux/module.h>
> +#include <linux/types.h>
> +#include <linux/slab.h>
> +#include <linux/usb.h>
> +#include <linux/i2c.h>
> +#include <linux/mutex.h>
> +#include <linux/platform_device.h>
> +#include <linux/mfd/core.h>
> +#include <linux/mfd/dln2.h>
> +
> +#define DRIVER_NAME			"usb-dln2"

Don't do this, just use "usb-dln2" where it needs to be used.

[...]

> +static struct usb_driver dln2_driver = {
> +	.name = DRIVER_NAME,
> +	.probe = dln2_probe,
> +	.disconnect = dln2_disconnect,
> +	.id_table = dln2_table,
> +};
> +
> +module_usb_driver(dln2_driver);
> +
> +MODULE_AUTHOR("Octavian Purdila <octavian.purdila@intel.com>");
> +MODULE_DESCRIPTION(DRIVER_NAME " driver");

This is not a description.

> +MODULE_LICENSE("GPL");

Header says v2.

> diff --git a/include/linux/mfd/dln2.h b/include/linux/mfd/dln2.h
> new file mode 100644
> index 0000000..197565d
> --- /dev/null
> +++ b/include/linux/mfd/dln2.h
> @@ -0,0 +1,71 @@
> +#ifndef __LINUX_USB_DLN2_H
> +#define __LINUX_USB_DLN2_H
> +
> +#define DLN2_CMD(cmd, id)		((cmd) | ((id) << 8))
> +
> +struct dln2_platform_data {
> +	u16 handle;
> +	union {
> +		struct {
> +			u8 port;
> +		} i2c;
> +	};
> +};

Why this complexity?
Octavian Purdila Sept. 17, 2014, 7:25 a.m. UTC | #2
On Wed, Sep 17, 2014 at 2:21 AM, Lee Jones <lee.jones@linaro.org> wrote:
>
> On Tue, 09 Sep 2014, Octavian Purdila wrote:
>
> > This patch implements the USB part of the Diolan USB-I2C/SPI/GPIO
> > Master Adapter DLN-2. Details about the device can be found here:
> >
> > https://www.diolan.com/i2c/i2c_interface.html.
> >
> > Information about the USB protocol can be found in the Programmer's
> > Reference Manual [1], see section 1.7.
>
> This driver really needs a USB Ack before I can accept it.
>

Greg, Johan, is the driver acceptable now?

> > Because the hardware has a single transmit endpoint and a single
> > receive endpoint the communication between the various DLN2 drivers
> > and the hardware will be muxed/demuxed by this driver.
> >
> > Each DLN2 module will be identified by the handle field within the DLN2
> > message header. If a DLN2 module issues multiple commands in parallel
> > they will be identified by the echo counter field in the message header.
> >
> > The DLN2 modules can use the dln2_transfer() function to issue a
> > command and wait for its response. They can also register a callback
> > that is going to be called when a specific event id is generated by
> > the device (e.g. GPIO interrupts). The device uses handle 0 for
> > sending events.
> >
> > [1] https://www.diolan.com/downloads/dln-api-manual.pdf
> >
> > Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
> > ---
> >  drivers/mfd/Kconfig      |   9 +
> >  drivers/mfd/Makefile     |   1 +
> >  drivers/mfd/dln2.c       | 681 +++++++++++++++++++++++++++++++++++++++++++++++
> >  include/linux/mfd/dln2.h |  71 +++++
> >  4 files changed, 762 insertions(+)
> >  create mode 100644 drivers/mfd/dln2.c
> >  create mode 100644 include/linux/mfd/dln2.h
>
> [...]
>
> > diff --git a/drivers/mfd/dln2.c b/drivers/mfd/dln2.c
> > new file mode 100644
> > index 0000000..b551b5e
> > --- /dev/null
> > +++ b/drivers/mfd/dln2.c
> > @@ -0,0 +1,681 @@
> > +/*
> > + * Driver for the Diolan DLN-2 USB adapter
> > + *
> > + * Copyright (c) 2014 Intel Corporation
> > + *
> > + * Derived from:
> > + *  i2c-diolan-u2c.c
> > + *  Copyright (c) 2010-2011 Ericsson AB
> > + *
> > + * This program is free software; you can redistribute it and/or
> > + * modify it under the terms of the GNU General Public License as
> > + * published by the Free Software Foundation, version 2.
> > + */
> > +
> > +#include <linux/kernel.h>
> > +#include <linux/errno.h>
>
> What are you using this for?
>

Not needed, I will remove it.

> > +#include <linux/module.h>
> > +#include <linux/types.h>
> > +#include <linux/slab.h>
> > +#include <linux/usb.h>
> > +#include <linux/i2c.h>
> > +#include <linux/mutex.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/mfd/core.h>
> > +#include <linux/mfd/dln2.h>
> > +
> > +#define DRIVER_NAME                  "usb-dln2"
>
> Don't do this, just use "usb-dln2" where it needs to be used.
>

Will do.

> [...]
>
> > +static struct usb_driver dln2_driver = {
> > +     .name = DRIVER_NAME,
> > +     .probe = dln2_probe,
> > +     .disconnect = dln2_disconnect,
> > +     .id_table = dln2_table,
> > +};
> > +
> > +module_usb_driver(dln2_driver);
> > +
> > +MODULE_AUTHOR("Octavian Purdila <octavian.purdila@intel.com>");
> > +MODULE_DESCRIPTION(DRIVER_NAME " driver");
>
> This is not a description.
>
> > +MODULE_LICENSE("GPL");
>
> Header says v2.
>

I will change it to GPL v2.

> > diff --git a/include/linux/mfd/dln2.h b/include/linux/mfd/dln2.h
> > new file mode 100644
> > index 0000000..197565d
> > --- /dev/null
> > +++ b/include/linux/mfd/dln2.h
> > @@ -0,0 +1,71 @@
> > +#ifndef __LINUX_USB_DLN2_H
> > +#define __LINUX_USB_DLN2_H
> > +
> > +#define DLN2_CMD(cmd, id)            ((cmd) | ((id) << 8))
> > +
> > +struct dln2_platform_data {
> > +     u16 handle;
> > +     union {
> > +             struct {
> > +                     u8 port;
> > +             } i2c;
> > +     };
> > +};
>
> Why this complexity?
>

There is also an SPI interface on this adapter which will probably the
port information and maybe some additional information. Would you
prefer to add the union later, when we add the SPI driver?
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Johan Hovold Sept. 17, 2014, 7:38 a.m. UTC | #3
On Wed, Sep 17, 2014 at 10:25:18AM +0300, Octavian Purdila wrote:
> On Wed, Sep 17, 2014 at 2:21 AM, Lee Jones <lee.jones@linaro.org> wrote:
> >
> > On Tue, 09 Sep 2014, Octavian Purdila wrote:
> >
> > > This patch implements the USB part of the Diolan USB-I2C/SPI/GPIO
> > > Master Adapter DLN-2. Details about the device can be found here:
> > >
> > > https://www.diolan.com/i2c/i2c_interface.html.
> > >
> > > Information about the USB protocol can be found in the Programmer's
> > > Reference Manual [1], see section 1.7.
> >
> > This driver really needs a USB Ack before I can accept it.
> >
> 
> Greg, Johan, is the driver acceptable now?

I started looking through v4 yesterday and found a few more things. Will
send you some you comments shortly.

Johan
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Johan Hovold Sept. 17, 2014, 9:10 a.m. UTC | #4
On Tue, Sep 09, 2014 at 10:24:44PM +0300, Octavian Purdila wrote:
> This patch implements the USB part of the Diolan USB-I2C/SPI/GPIO
> Master Adapter DLN-2. Details about the device can be found here:
> 
> https://www.diolan.com/i2c/i2c_interface.html.
> 
> Information about the USB protocol can be found in the Programmer's
> Reference Manual [1], see section 1.7.
> 
> Because the hardware has a single transmit endpoint and a single
> receive endpoint the communication between the various DLN2 drivers
> and the hardware will be muxed/demuxed by this driver.
> 
> Each DLN2 module will be identified by the handle field within the DLN2
> message header. If a DLN2 module issues multiple commands in parallel
> they will be identified by the echo counter field in the message header.
> 
> The DLN2 modules can use the dln2_transfer() function to issue a
> command and wait for its response. They can also register a callback
> that is going to be called when a specific event id is generated by
> the device (e.g. GPIO interrupts). The device uses handle 0 for
> sending events.
> 
> [1] https://www.diolan.com/downloads/dln-api-manual.pdf
> 
> Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
> ---
>  drivers/mfd/Kconfig      |   9 +
>  drivers/mfd/Makefile     |   1 +
>  drivers/mfd/dln2.c       | 681 +++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/mfd/dln2.h |  71 +++++
>  4 files changed, 762 insertions(+)
>  create mode 100644 drivers/mfd/dln2.c
>  create mode 100644 include/linux/mfd/dln2.h
> 
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index de5abf2..7bcf895 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -183,6 +183,15 @@ config MFD_DA9063
>  	  Additional drivers must be enabled in order to use the functionality
>  	  of the device.
>  
> +config MFD_DLN2
> +	tristate "Diolan DLN2 support"
> +	select MFD_CORE
> +	depends on USB
> +	help
> +	  This adds support for Diolan USB-I2C/SPI/GPIO Master Adapter DLN-2.
> +	  Additional drivers must be enabled in order to use the functionality
> +	  of the device.
> +
>  config MFD_MC13XXX
>  	tristate
>  	depends on (SPI_MASTER || I2C)
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index f001487..591988d 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -169,6 +169,7 @@ obj-$(CONFIG_MFD_AS3711)	+= as3711.o
>  obj-$(CONFIG_MFD_AS3722)	+= as3722.o
>  obj-$(CONFIG_MFD_STW481X)	+= stw481x.o
>  obj-$(CONFIG_MFD_IPAQ_MICRO)	+= ipaq-micro.o
> +obj-$(CONFIG_MFD_DLN2)		+= dln2.o
>  
>  intel-soc-pmic-objs		:= intel_soc_pmic_core.o intel_soc_pmic_crc.o
>  obj-$(CONFIG_INTEL_SOC_PMIC)	+= intel-soc-pmic.o
> diff --git a/drivers/mfd/dln2.c b/drivers/mfd/dln2.c
> new file mode 100644
> index 0000000..b551b5e
> --- /dev/null
> +++ b/drivers/mfd/dln2.c
> @@ -0,0 +1,681 @@
> +/*
> + * Driver for the Diolan DLN-2 USB adapter
> + *
> + * Copyright (c) 2014 Intel Corporation
> + *
> + * Derived from:
> + *  i2c-diolan-u2c.c
> + *  Copyright (c) 2010-2011 Ericsson AB
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation, version 2.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/errno.h>
> +#include <linux/module.h>
> +#include <linux/types.h>
> +#include <linux/slab.h>
> +#include <linux/usb.h>
> +#include <linux/i2c.h>
> +#include <linux/mutex.h>
> +#include <linux/platform_device.h>
> +#include <linux/mfd/core.h>
> +#include <linux/mfd/dln2.h>
> +
> +#define DRIVER_NAME			"usb-dln2"
> +
> +struct dln2_header {
> +	__le16 size;
> +	__le16 id;
> +	__le16 echo;
> +	__le16 handle;
> +} __packed;
> +
> +struct dln2_response {
> +	struct dln2_header hdr;
> +	__le16 result;
> +} __packed;
> +
> +#define DLN2_GENERIC_MODULE_ID		0x00
> +#define DLN2_GENERIC_CMD(cmd)		DLN2_CMD(cmd, DLN2_GENERIC_MODULE_ID)
> +#define CMD_GET_DEVICE_VER		DLN2_GENERIC_CMD(0x30)
> +#define CMD_GET_DEVICE_SN		DLN2_GENERIC_CMD(0x31)
> +
> +#define DLN2_HW_ID			0x200
> +#define DLN2_USB_TIMEOUT		200	/* in ms */
> +#define DLN2_MAX_RX_SLOTS		16
> +#define DLN2_MAX_MODULES		5

Reduce to 4 until you implement support for more modules and save some
memory meanwhile? (Or is id 4 already used?)

> +#define DLN2_MAX_URBS			16
> +#define DLN2_RX_BUF_SIZE		512
> +
> +#define DLN2_HANDLE_EVENT		0
> +#define DLN2_HANDLE_CTRL		1
> +#define DLN2_HANDLE_GPIO		2
> +#define DLN2_HANDLE_I2C			3
> +
> +/*
> + * Receive context used between the receive demultiplexer and the
> + * transfer routine. While sending a request the transfer routine
> + * will look for a free receive context and use it to wait for a
> + * response and to receive the URB and thus the response data.
> + */
> +struct dln2_rx_context {
> +	struct completion done;
> +	struct urb *urb;
> +	bool connected;
> +};
> +
> +/*
> + * Receive contexts for a particular DLN2 module (i2c, gpio, etc.). We
> + * use the handle header field to indentify the module in
> + * dln2_dev.mod_rx_slots and then the echo header field to index the
> + * slots field and find the receive context for a particular
> + * request.
> + */
> +struct dln2_mod_rx_slots {
> +	/* RX slots bitmap */
> +	unsigned long bmap;
> +
> +	/* used to wait for a free RX slot */
> +	wait_queue_head_t wq;
> +
> +	/* used to wait for an RX operation to complete */
> +	struct dln2_rx_context slots[DLN2_MAX_RX_SLOTS];
> +
> +	/* avoid races between free_rx_slot and dln2_rx_transfer */
> +	spinlock_t lock;
> +};
> +
> +struct dln2_dev {
> +	struct usb_device *usb_dev;
> +	struct usb_interface *interface;
> +	u8 ep_in;
> +	u8 ep_out;
> +
> +	struct urb *rx_urb[DLN2_MAX_URBS];
> +	void *rx_buf[DLN2_MAX_URBS];
> +
> +	struct dln2_mod_rx_slots mod_rx_slots[DLN2_MAX_MODULES];
> +
> +	struct list_head rx_cb_list;
> +	spinlock_t rx_cb_lock;
> +};
> +
> +static bool find_free_slot(struct dln2_mod_rx_slots *rxs, int *slot)
> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&rxs->lock, flags);
> +
> +	*slot = find_first_zero_bit(&rxs->bmap, DLN2_MAX_RX_SLOTS);
> +
> +	if (*slot < DLN2_MAX_RX_SLOTS) {
> +		struct dln2_rx_context *rxc = &rxs->slots[*slot];
> +
> +		set_bit(*slot, &rxs->bmap);
> +		rxc->connected = true;
> +	}
> +
> +	spin_unlock_irqrestore(&rxs->lock, flags);
> +
> +	return *slot < DLN2_MAX_RX_SLOTS;
> +}
> +
> +static int alloc_rx_slot(struct dln2_mod_rx_slots *rxs)
> +{
> +	int ret;
> +	int slot;
> +
> +	/* No need to timeout here, the wait is bounded by the timeout
> +	 * in _dln2_transfer
> +	 */

Multi-comment style, again.

> +	ret = wait_event_interruptible(rxs->wq, find_free_slot(rxs, &slot));
> +	if (ret < 0)
> +		return ret;
> +
> +	return slot;
> +}

<snip>

> +static struct dln2_platform_data dln2_pdata_gpio = {
> +	.handle = DLN2_HANDLE_GPIO,
> +};
> +
> +/* Right now only one I2C port seems to be supported */
> +static struct dln2_platform_data dln2_pdata_i2c = {
> +	.handle = DLN2_HANDLE_I2C,
> +	.i2c = {
> +		.port = 0,
> +	},
> +};
> +
> +static const struct mfd_cell dln2_devs[] = {
> +	{
> +		.name	= "dln2-gpio",

Drop indentation     ^

> +		.platform_data = &dln2_pdata_gpio,
> +		.pdata_size = sizeof(struct dln2_platform_data),
> +	},
> +	{
> +		.name	= "dln2-i2c",

Ditto

> +		.platform_data = &dln2_pdata_i2c,
> +		.pdata_size = sizeof(struct dln2_platform_data),
> +	},
> +};
> +
> +static void dln2_disconnect(struct usb_interface *interface)
> +{
> +	struct dln2_dev *dln2 = usb_get_intfdata(interface);
> +
> +	mfd_remove_devices(&interface->dev);
> +	dln2_free(dln2);
> +}
> +
> +static int dln2_probe(struct usb_interface *interface,
> +		      const struct usb_device_id *id)
> +{
> +	struct usb_host_interface *hostif = interface->cur_altsetting;
> +	struct device *dev = &interface->dev;
> +	struct dln2_dev *dln2;
> +	int ret;
> +	int i, j;
> +
> +	if (hostif->desc.bInterfaceNumber != 0 ||
> +	    hostif->desc.bNumEndpoints < 2)
> +		return -ENODEV;
> +
> +	dln2 = kzalloc(sizeof(*dln2), GFP_KERNEL);
> +	if (!dln2)
> +		return -ENOMEM;
> +
> +	dln2->ep_out = hostif->endpoint[0].desc.bEndpointAddress;
> +	dln2->ep_in = hostif->endpoint[1].desc.bEndpointAddress;
> +	dln2->usb_dev = usb_get_dev(interface_to_usbdev(interface));
> +	dln2->interface = interface;
> +	usb_set_intfdata(interface, dln2);
> +
> +	for (i = 0; i < DLN2_MAX_MODULES; i++) {
> +		init_waitqueue_head(&dln2->mod_rx_slots[i].wq);
> +		spin_lock_init(&dln2->mod_rx_slots[i].lock);
> +		for (j = 0; j < DLN2_MAX_RX_SLOTS; j++)
> +			init_completion(&dln2->mod_rx_slots[i].slots[j].done);
> +	}
> +
> +	spin_lock_init(&dln2->rx_cb_lock);
> +	INIT_LIST_HEAD(&dln2->rx_cb_list);
> +
> +	ret = dln2_setup_rx_urbs(dln2, hostif);
> +	if (ret) {
> +		dln2_free(dln2);
> +		return ret;
> +	}
> +
> +	ret = dln2_hw_init(dln2);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to initialize hardware\n");
> +		goto out_cleanup;
> +	}
> +
> +	ret = mfd_add_devices(dev, -1, dln2_devs, ARRAY_SIZE(dln2_devs),
> +			      NULL, 0, NULL);
> +	if (ret != 0) {
> +		dev_err(dev, "Failed to add mfd devices to core.\n");
> +		goto out_cleanup;
> +	}

You cannot use id -1 (PLATFORM_DEVID_NONE) here. You either need to use
a unique id base or use -2 (PLATFORM_DEVID_AUTO) so that a platform
device id is assigned automatically.

Currently, the platform devices end up being named

	dln2-gpio
	dln2-i2c

without unique ids in sysfs. When you connect a second DLN2 device your
driver will try to register the same names and fail:

[ 2146.320648] ------------[ cut here ]------------
[ 2146.320831] WARNING: CPU: 0 PID: 178 at /home/johan/work/omicron/src/linux/fs/sysfs/dir.c:31 sysfs_warn_dup+0x74/0x84()
[ 2146.320922] sysfs: cannot create duplicate filename '/bus/platform/devices/dln2-gpio'
[ 2146.321014] Modules linked in: i2c_dln2 gpio_dln2 dln2 netconsole [last unloaded: dln2]
[ 2146.323974] CPU: 0 PID: 178 Comm: bash Tainted: G        W      3.17.0-rc3 #9
[ 2146.324737] [<c0016bec>] (unwind_backtrace) from [<c0013850>] (show_stack+0x20/0x24)
[ 2146.324890] [<c0013850>] (show_stack) from [<c042cb74>] (dump_stack+0x24/0x28)
[ 2146.326538] [<c042cb74>] (dump_stack) from [<c0040ff4>] (warn_slowpath_common+0x80/0x98)
[ 2146.326721] [<c0040ff4>] (warn_slowpath_common) from [<c004104c>] (warn_slowpath_fmt+0x40/0x48)
[ 2146.326812] [<c004104c>] (warn_slowpath_fmt) from [<c016ee54>] (sysfs_warn_dup+0x74/0x84)
[ 2146.326904] [<c016ee54>] (sysfs_warn_dup) from [<c016f1e0>] (sysfs_do_create_link_sd.isra.2+0xcc/0xd0)
[ 2146.327026] [<c016f1e0>] (sysfs_do_create_link_sd.isra.2) from [<c016f220>] (sysfs_create_link+0x3c/0x48)
[ 2146.328338] [<c016f220>] (sysfs_create_link) from [<c0286474>] (bus_add_device+0x12c/0x1e0)
[ 2146.328460] [<c0286474>] (bus_add_device) from [<c02844a8>] (device_add+0x410/0x584)
[ 2146.328552] [<c02844a8>] (device_add) from [<c02890c8>] (platform_device_add+0xd8/0x26c)
[ 2146.328643] [<c02890c8>] (platform_device_add) from [<c02a571c>] (mfd_add_device+0x23c/0x3a0)
[ 2146.328735] [<c02a571c>] (mfd_add_device) from [<c02a5978>] (mfd_add_devices+0xb8/0x110)
[ 2146.328857] [<c02a5978>] (mfd_add_devices) from [<bf0ac800>] (dln2_probe+0x1f4/0x250 [dln2])
[ 2146.328948] [<bf0ac800>] (dln2_probe [dln2]) from [<c030bc98>] (usb_probe_interface+0x1bc/0x2a8)
[ 2146.329071] [<c030bc98>] (usb_probe_interface) from [<c0287314>] (driver_probe_device+0x14c/0x3ac)
[ 2146.330718] [<c0287314>] (driver_probe_device) from [<c028766c>] (__driver_attach+0xa4/0xa8)
[ 2146.330810] [<c028766c>] (__driver_attach) from [<c0285320>] (bus_for_each_dev+0x70/0xa4)
[ 2146.330902] [<c0285320>] (bus_for_each_dev) from [<c0286cb8>] (driver_attach+0x2c/0x30)
[ 2146.330993] [<c0286cb8>] (driver_attach) from [<c0309f20>] (usb_store_new_id+0x170/0x1ac)
[ 2146.331909] [<c0309f20>] (usb_store_new_id) from [<c0309f90>] (new_id_store+0x34/0x3c)
[ 2146.332000] [<c0309f90>] (new_id_store) from [<c0285074>] (drv_attr_store+0x30/0x3c)
[ 2146.332611] [<c0285074>] (drv_attr_store) from [<c016e740>] (sysfs_kf_write+0x5c/0x60)
[ 2146.332702] [<c016e740>] (sysfs_kf_write) from [<c016d900>] (kernfs_fop_write+0xd4/0x194)
[ 2146.332794] [<c016d900>] (kernfs_fop_write) from [<c010fde8>] (vfs_write+0xb4/0x1c0)
[ 2146.332916] [<c010fde8>] (vfs_write) from [<c0110450>] (SyS_write+0x4c/0xa0)
[ 2146.333007] [<c0110450>] (SyS_write) from [<c000f900>] (ret_fast_syscall+0x0/0x48)
[ 2146.333984] ---[ end trace ad1c64348c92978a ]---
[ 2146.334625] usb-dln2 1-2.1:1.0: Failed to add mfd devices to core.
[ 2146.334930] usb-dln2: probe of 1-2.1:1.0 failed with error -17


I noticed that the other two USB MFD drivers suffer from similar
problems. The rtsx_usb driver almost gets it right by using the usb
device number (address) but that is only unique per bus. I suggest using

	bus_num << 8 | devnum

as a base for USB MFD device ids instead. Note however that this might
still not be sufficient if there are ever USB-MFD drivers with multiple
cells of the same type (with increasing cell ids). (That could of course
then be solved by further shifting.)

Unless anyone suggests otherwise (e.g. to stick with auto id), I'll add
a helper function for this and fix up those two drivers.

Johan
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Lee Jones Sept. 17, 2014, 3:46 p.m. UTC | #5
On Wed, 17 Sep 2014, Johan Hovold wrote:
> On Tue, Sep 09, 2014 at 10:24:44PM +0300, Octavian Purdila wrote:
> > This patch implements the USB part of the Diolan USB-I2C/SPI/GPIO
> > Master Adapter DLN-2. Details about the device can be found here:
> > 
> > https://www.diolan.com/i2c/i2c_interface.html.
> > 
> > Information about the USB protocol can be found in the Programmer's
> > Reference Manual [1], see section 1.7.
> > 
> > Because the hardware has a single transmit endpoint and a single
> > receive endpoint the communication between the various DLN2 drivers
> > and the hardware will be muxed/demuxed by this driver.
> > 
> > Each DLN2 module will be identified by the handle field within the DLN2
> > message header. If a DLN2 module issues multiple commands in parallel
> > they will be identified by the echo counter field in the message header.
> > 
> > The DLN2 modules can use the dln2_transfer() function to issue a
> > command and wait for its response. They can also register a callback
> > that is going to be called when a specific event id is generated by
> > the device (e.g. GPIO interrupts). The device uses handle 0 for
> > sending events.
> > 
> > [1] https://www.diolan.com/downloads/dln-api-manual.pdf
> > 
> > Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
> > ---
> >  drivers/mfd/Kconfig      |   9 +
> >  drivers/mfd/Makefile     |   1 +
> >  drivers/mfd/dln2.c       | 681 +++++++++++++++++++++++++++++++++++++++++++++++
> >  include/linux/mfd/dln2.h |  71 +++++
> >  4 files changed, 762 insertions(+)
> >  create mode 100644 drivers/mfd/dln2.c
> >  create mode 100644 include/linux/mfd/dln2.h

[...]

> Unless anyone suggests otherwise (e.g. to stick with auto id), I'll add
> a helper function for this and fix up those two drivers.

Appreciated.
Lee Jones Sept. 17, 2014, 3:56 p.m. UTC | #6
On Wed, 17 Sep 2014, Octavian Purdila wrote:
> On Wed, Sep 17, 2014 at 2:21 AM, Lee Jones <lee.jones@linaro.org> wrote:
> >
> > On Tue, 09 Sep 2014, Octavian Purdila wrote:
> >
> > > This patch implements the USB part of the Diolan USB-I2C/SPI/GPIO
> > > Master Adapter DLN-2. Details about the device can be found here:
> > >
> > > https://www.diolan.com/i2c/i2c_interface.html.
> > >
> > > Information about the USB protocol can be found in the Programmer's
> > > Reference Manual [1], see section 1.7.
> > >
> > > Because the hardware has a single transmit endpoint and a single
> > > receive endpoint the communication between the various DLN2 drivers
> > > and the hardware will be muxed/demuxed by this driver.
> > >
> > > Each DLN2 module will be identified by the handle field within the DLN2
> > > message header. If a DLN2 module issues multiple commands in parallel
> > > they will be identified by the echo counter field in the message header.
> > >
> > > The DLN2 modules can use the dln2_transfer() function to issue a
> > > command and wait for its response. They can also register a callback
> > > that is going to be called when a specific event id is generated by
> > > the device (e.g. GPIO interrupts). The device uses handle 0 for
> > > sending events.
> > >
> > > [1] https://www.diolan.com/downloads/dln-api-manual.pdf
> > >
> > > Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
> > > ---
> > >  drivers/mfd/Kconfig      |   9 +
> > >  drivers/mfd/Makefile     |   1 +
> > >  drivers/mfd/dln2.c       | 681 +++++++++++++++++++++++++++++++++++++++++++++++
> > >  include/linux/mfd/dln2.h |  71 +++++
> > >  4 files changed, 762 insertions(+)
> > >  create mode 100644 drivers/mfd/dln2.c
> > >  create mode 100644 include/linux/mfd/dln2.h

[...]

> > > diff --git a/include/linux/mfd/dln2.h b/include/linux/mfd/dln2.h
> > > new file mode 100644
> > > index 0000000..197565d
> > > --- /dev/null
> > > +++ b/include/linux/mfd/dln2.h
> > > @@ -0,0 +1,71 @@
> > > +#ifndef __LINUX_USB_DLN2_H
> > > +#define __LINUX_USB_DLN2_H
> > > +
> > > +#define DLN2_CMD(cmd, id)            ((cmd) | ((id) << 8))
> > > +
> > > +struct dln2_platform_data {
> > > +     u16 handle;
> > > +     union {
> > > +             struct {
> > > +                     u8 port;
> > > +             } i2c;
> > > +     };
> > > +};
> >
> > Why this complexity?
> 
> There is also an SPI interface on this adapter which will probably the
> port information and maybe some additional information. Would you
> prefer to add the union later, when we add the SPI driver?

Yes please.
Johan Hovold Sept. 18, 2014, 11:31 a.m. UTC | #7
On Tue, Sep 09, 2014 at 10:24:44PM +0300, Octavian Purdila wrote:

> +static int alloc_rx_slot(struct dln2_mod_rx_slots *rxs)
> +{
> +	int ret;
> +	int slot;
> +
> +	/* No need to timeout here, the wait is bounded by the timeout
> +	 * in _dln2_transfer
> +	 */
> +	ret = wait_event_interruptible(rxs->wq, find_free_slot(rxs, &slot));
> +	if (ret < 0)
> +		return ret;
> +
> +	return slot;
> +}
> +
> +static void free_rx_slot(struct dln2_dev *dln2, struct dln2_mod_rx_slots *rxs,
> +			 int slot)
> +{
> +	struct urb *urb = NULL;
> +	unsigned long flags;
> +	struct dln2_rx_context *rxc;
> +	struct device *dev = &dln2->interface->dev;
> +	int ret;
> +
> +	spin_lock_irqsave(&rxs->lock, flags);
> +
> +	clear_bit(slot, &rxs->bmap);
> +
> +	rxc = &rxs->slots[slot];
> +	rxc->connected = false;
> +	urb = rxc->urb;
> +	rxc->urb = NULL;
> +	reinit_completion(&rxc->done);
> +
> +	spin_unlock_irqrestore(&rxs->lock, flags);
> +
> +	if (urb)  {
> +		ret = usb_submit_urb(urb, GFP_KERNEL);
> +		if (ret < 0)
> +			dev_err(dev, "failed to re-submit RX URB: %d\n", ret);
> +	}
> +
> +	wake_up_interruptible(&rxs->wq);
> +}

> +static void dln2_rx_transfer(struct dln2_dev *dln2, struct urb *urb,
> +			     u16 handle, u16 rx_slot)
> +{
> +	struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[handle];
> +	struct dln2_rx_context *rxc;
> +	struct device *dev = &dln2->interface->dev;
> +	int err;
> +
> +	spin_lock(&rxs->lock);
> +	rxc = &rxs->slots[rx_slot];
> +	if (rxc->connected) {
> +		rxc->urb = urb;
> +		complete(&rxc->done);
> +	} else {
> +		dev_warn(dev, "dropping response %d/%d", handle, rx_slot);
> +		err = usb_submit_urb(urb, GFP_ATOMIC);
> +		if (err < 0)
> +			dev_err(dev, "failed to re-submit RX URB: %d\n", err);
> +	}
> +	spin_unlock(&rxs->lock);
> +}

> +static void dln2_rx(struct urb *urb)
> +{
> +	int err;
> +	struct dln2_dev *dln2 = urb->context;
> +	struct dln2_header *hdr = urb->transfer_buffer;
> +	struct device *dev = &dln2->interface->dev;
> +	u16 id, echo, handle, size;
> +	u8 *data;
> +	int len;
> +
> +	switch (urb->status) {
> +	case 0:
> +		/* success */
> +		break;
> +	case -ECONNRESET:
> +	case -ENOENT:
> +	case -ESHUTDOWN:
> +	case -EPIPE:
> +		/* this urb is terminated, clean up */
> +		dev_dbg(dev, "urb shutting down with status %d\n", urb->status);
> +		return;
> +	default:
> +		dev_dbg(dev, "nonzero urb status received %d\n", urb->status);
> +		goto out;
> +	}
> +
> +	if (urb->actual_length < sizeof(struct dln2_header)) {
> +		dev_err(dev, "short response: %d\n", urb->actual_length);
> +		goto out;
> +	}
> +
> +	handle = le16_to_cpu(hdr->handle);
> +	id = le16_to_cpu(hdr->id);
> +	echo = le16_to_cpu(hdr->echo);
> +	size = le16_to_cpu(hdr->size);
> +
> +	if (size != urb->actual_length) {
> +		dev_err(dev, "size mismatch: handle %x cmd %x echo %x size %d actual %d\n",
> +			handle, id, echo, size, urb->actual_length);
> +		goto out;
> +	}
> +
> +	if (handle >= DLN2_MAX_MODULES) {
> +		dev_warn(dev, "RX: invalid handle %d\n", handle);
> +		goto out;
> +	}
> +
> +	data = urb->transfer_buffer + sizeof(struct dln2_header);
> +	len = urb->actual_length - sizeof(struct dln2_header);
> +
> +	if (handle == DLN2_HANDLE_EVENT) {
> +		dln2_run_rx_callbacks(dln2, id, echo, data, len);
> +		err = usb_submit_urb(urb, GFP_ATOMIC);
> +		if (err < 0)
> +			goto out_submit_failed;
> +	} else {
> +		dln2_rx_transfer(dln2, urb, handle, echo);
> +	}
> +
> +	return;
> +
> +out:
> +	err = usb_submit_urb(urb, GFP_ATOMIC);
> +out_submit_failed:
> +	if (err < 0)
> +		dev_err(dev, "failed to re-submit RX URB: %d\n", err);
> +}

> +static int _dln2_transfer(struct dln2_dev *dln2, u16 handle, u16 cmd,
> +			  const void *obuf, unsigned obuf_len,
> +			  void *ibuf, unsigned *ibuf_len)
> +{
> +	int ret = 0;
> +	u16 result;
> +	int rx_slot;
> +	struct dln2_response *rsp;
> +	struct dln2_rx_context *rxc;
> +	struct device *dev = &dln2->interface->dev;
> +	const int timeout = DLN2_USB_TIMEOUT * HZ / 1000;
> +	struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[handle];
> +
> +	rx_slot = alloc_rx_slot(rxs);
> +	if (rx_slot < 0)
> +		return rx_slot;
> +
> +	ret = dln2_send_wait(dln2, handle, cmd, rx_slot, obuf, obuf_len);
> +	if (ret < 0) {
> +		free_rx_slot(dln2, rxs, rx_slot);
> +		dev_err(dev, "USB write failed: %d", ret);
> +		return ret;
> +	}
> +
> +	rxc = &rxs->slots[rx_slot];
> +
> +	ret = wait_for_completion_interruptible_timeout(&rxc->done, timeout);
> +	if (ret <= 0) {
> +		if (!ret)
> +			ret = -ETIMEDOUT;
> +		goto out_free_rx_slot;
> +	}
> +
> +	/* if we got here we know that the response header has been checked */
> +	rsp = rxc->urb->transfer_buffer;
> +	if (rsp->hdr.size < sizeof(*rsp)) {
> +		ret = -EPROTO;
> +		goto out_free_rx_slot;
> +	}
> +
> +	result = le16_to_cpu(rsp->result);
> +	if (result) {
> +		dev_dbg(dev, "%d received response with error %d\n",
> +			handle, result);
> +		ret = -EREMOTEIO;
> +		goto out_free_rx_slot;
> +	}
> +
> +	if (!ibuf) {
> +		ret = 0;
> +		goto out_free_rx_slot;
> +	}
> +
> +	if (*ibuf_len > rsp->hdr.size - sizeof(*rsp))
> +		*ibuf_len = rsp->hdr.size - sizeof(*rsp);
> +
> +	memcpy(ibuf, rsp + 1, *ibuf_len);
> +
> +out_free_rx_slot:
> +	free_rx_slot(dln2, rxs, rx_slot);
> +
> +	return ret;
> +}
> +
> +int dln2_transfer(struct platform_device *pdev, u16 cmd,
> +		  const void *obuf, unsigned obuf_len,
> +		  void *ibuf, unsigned *ibuf_len)
> +{
> +	struct dln2_platform_data *dln2_pdata;
> +	struct dln2_dev *dln2;
> +	u16 h;
> +
> +	/* USB device has been disconnected, bail out */
> +	if (!pdev)
> +		return -ENODEV;

This isn't sufficient to prevent I/O after disconnect, or worse.

You set pdev to NULL in the platform device's remove callbacks, but you
have no synchronisation.

To take one example: in _dln2_transfer above you wait for completion,
but you never wake the process up in case the urb is killed due to a
disconnect. Hence you get a timeout much later, call free_rx_slot which
tries to send of another urb using potentially already freed data.

> +
> +	dln2 = dev_get_drvdata(pdev->dev.parent);
> +	dln2_pdata = dev_get_platdata(&pdev->dev);
> +	h = dln2_pdata->handle;
> +
> +	return _dln2_transfer(dln2, h, cmd, obuf, obuf_len, ibuf, ibuf_len);
> +}
> +EXPORT_SYMBOL(dln2_transfer);

> +static void dln2_free_rx_urbs(struct dln2_dev *dln2)
> +{
> +	int i;
> +
> +	for (i = 0; i < DLN2_MAX_URBS; i++) {
> +		usb_kill_urb(dln2->rx_urb[i]);
> +		usb_free_urb(dln2->rx_urb[i]);
> +		kfree(dln2->rx_buf[i]);
> +	}
> +}
> +
> +static void dln2_free(struct dln2_dev *dln2)
> +{
> +	dln2_free_rx_urbs(dln2);
> +	usb_put_dev(dln2->usb_dev);
> +	kfree(dln2);
> +}

> +static void dln2_disconnect(struct usb_interface *interface)
> +{
> +	struct dln2_dev *dln2 = usb_get_intfdata(interface);
> +
> +	mfd_remove_devices(&interface->dev);

You need to make sure all I/O has stopped here.

> +	dln2_free(dln2);
> +}

Johan
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Johan Hovold Sept. 18, 2014, 2:21 p.m. UTC | #8
On Tue, Sep 09, 2014 at 10:24:44PM +0300, Octavian Purdila wrote:

> +MODULE_AUTHOR("Octavian Purdila <octavian.purdila@intel.com>");
> +MODULE_DESCRIPTION(DRIVER_NAME " driver");
> +MODULE_LICENSE("GPL");

Just noticed both the i2c and gpio driver is lacking a MODULE_ALIAS to
enable module auto-loading.

Johan
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Patch
diff mbox

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index de5abf2..7bcf895 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -183,6 +183,15 @@  config MFD_DA9063
 	  Additional drivers must be enabled in order to use the functionality
 	  of the device.
 
+config MFD_DLN2
+	tristate "Diolan DLN2 support"
+	select MFD_CORE
+	depends on USB
+	help
+	  This adds support for Diolan USB-I2C/SPI/GPIO Master Adapter DLN-2.
+	  Additional drivers must be enabled in order to use the functionality
+	  of the device.
+
 config MFD_MC13XXX
 	tristate
 	depends on (SPI_MASTER || I2C)
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index f001487..591988d 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -169,6 +169,7 @@  obj-$(CONFIG_MFD_AS3711)	+= as3711.o
 obj-$(CONFIG_MFD_AS3722)	+= as3722.o
 obj-$(CONFIG_MFD_STW481X)	+= stw481x.o
 obj-$(CONFIG_MFD_IPAQ_MICRO)	+= ipaq-micro.o
+obj-$(CONFIG_MFD_DLN2)		+= dln2.o
 
 intel-soc-pmic-objs		:= intel_soc_pmic_core.o intel_soc_pmic_crc.o
 obj-$(CONFIG_INTEL_SOC_PMIC)	+= intel-soc-pmic.o
diff --git a/drivers/mfd/dln2.c b/drivers/mfd/dln2.c
new file mode 100644
index 0000000..b551b5e
--- /dev/null
+++ b/drivers/mfd/dln2.c
@@ -0,0 +1,681 @@ 
+/*
+ * Driver for the Diolan DLN-2 USB adapter
+ *
+ * Copyright (c) 2014 Intel Corporation
+ *
+ * Derived from:
+ *  i2c-diolan-u2c.c
+ *  Copyright (c) 2010-2011 Ericsson AB
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, version 2.
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/usb.h>
+#include <linux/i2c.h>
+#include <linux/mutex.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/dln2.h>
+
+#define DRIVER_NAME			"usb-dln2"
+
+struct dln2_header {
+	__le16 size;
+	__le16 id;
+	__le16 echo;
+	__le16 handle;
+} __packed;
+
+struct dln2_response {
+	struct dln2_header hdr;
+	__le16 result;
+} __packed;
+
+#define DLN2_GENERIC_MODULE_ID		0x00
+#define DLN2_GENERIC_CMD(cmd)		DLN2_CMD(cmd, DLN2_GENERIC_MODULE_ID)
+#define CMD_GET_DEVICE_VER		DLN2_GENERIC_CMD(0x30)
+#define CMD_GET_DEVICE_SN		DLN2_GENERIC_CMD(0x31)
+
+#define DLN2_HW_ID			0x200
+#define DLN2_USB_TIMEOUT		200	/* in ms */
+#define DLN2_MAX_RX_SLOTS		16
+#define DLN2_MAX_MODULES		5
+#define DLN2_MAX_URBS			16
+#define DLN2_RX_BUF_SIZE		512
+
+#define DLN2_HANDLE_EVENT		0
+#define DLN2_HANDLE_CTRL		1
+#define DLN2_HANDLE_GPIO		2
+#define DLN2_HANDLE_I2C			3
+
+/*
+ * Receive context used between the receive demultiplexer and the
+ * transfer routine. While sending a request the transfer routine
+ * will look for a free receive context and use it to wait for a
+ * response and to receive the URB and thus the response data.
+ */
+struct dln2_rx_context {
+	struct completion done;
+	struct urb *urb;
+	bool connected;
+};
+
+/*
+ * Receive contexts for a particular DLN2 module (i2c, gpio, etc.). We
+ * use the handle header field to indentify the module in
+ * dln2_dev.mod_rx_slots and then the echo header field to index the
+ * slots field and find the receive context for a particular
+ * request.
+ */
+struct dln2_mod_rx_slots {
+	/* RX slots bitmap */
+	unsigned long bmap;
+
+	/* used to wait for a free RX slot */
+	wait_queue_head_t wq;
+
+	/* used to wait for an RX operation to complete */
+	struct dln2_rx_context slots[DLN2_MAX_RX_SLOTS];
+
+	/* avoid races between free_rx_slot and dln2_rx_transfer */
+	spinlock_t lock;
+};
+
+struct dln2_dev {
+	struct usb_device *usb_dev;
+	struct usb_interface *interface;
+	u8 ep_in;
+	u8 ep_out;
+
+	struct urb *rx_urb[DLN2_MAX_URBS];
+	void *rx_buf[DLN2_MAX_URBS];
+
+	struct dln2_mod_rx_slots mod_rx_slots[DLN2_MAX_MODULES];
+
+	struct list_head rx_cb_list;
+	spinlock_t rx_cb_lock;
+};
+
+static bool find_free_slot(struct dln2_mod_rx_slots *rxs, int *slot)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&rxs->lock, flags);
+
+	*slot = find_first_zero_bit(&rxs->bmap, DLN2_MAX_RX_SLOTS);
+
+	if (*slot < DLN2_MAX_RX_SLOTS) {
+		struct dln2_rx_context *rxc = &rxs->slots[*slot];
+
+		set_bit(*slot, &rxs->bmap);
+		rxc->connected = true;
+	}
+
+	spin_unlock_irqrestore(&rxs->lock, flags);
+
+	return *slot < DLN2_MAX_RX_SLOTS;
+}
+
+static int alloc_rx_slot(struct dln2_mod_rx_slots *rxs)
+{
+	int ret;
+	int slot;
+
+	/* No need to timeout here, the wait is bounded by the timeout
+	 * in _dln2_transfer
+	 */
+	ret = wait_event_interruptible(rxs->wq, find_free_slot(rxs, &slot));
+	if (ret < 0)
+		return ret;
+
+	return slot;
+}
+
+static void free_rx_slot(struct dln2_dev *dln2, struct dln2_mod_rx_slots *rxs,
+			 int slot)
+{
+	struct urb *urb = NULL;
+	unsigned long flags;
+	struct dln2_rx_context *rxc;
+	struct device *dev = &dln2->interface->dev;
+	int ret;
+
+	spin_lock_irqsave(&rxs->lock, flags);
+
+	clear_bit(slot, &rxs->bmap);
+
+	rxc = &rxs->slots[slot];
+	rxc->connected = false;
+	urb = rxc->urb;
+	rxc->urb = NULL;
+	reinit_completion(&rxc->done);
+
+	spin_unlock_irqrestore(&rxs->lock, flags);
+
+	if (urb)  {
+		ret = usb_submit_urb(urb, GFP_KERNEL);
+		if (ret < 0)
+			dev_err(dev, "failed to re-submit RX URB: %d\n", ret);
+	}
+
+	wake_up_interruptible(&rxs->wq);
+}
+
+struct dln2_rx_cb_entry {
+	struct list_head list;
+	u16 id;
+	struct platform_device *pdev;
+	dln2_rx_cb_t callback;
+};
+
+int dln2_register_event_cb(struct platform_device *pdev, u16 id,
+			   dln2_rx_cb_t rx_cb)
+{
+	struct dln2_dev *dln2 = dev_get_drvdata(pdev->dev.parent);
+	struct dln2_rx_cb_entry *i, *new;
+	unsigned long flags;
+	int ret = 0;
+
+	new = kmalloc(sizeof(*new), GFP_KERNEL);
+	if (!new)
+		return -ENOMEM;
+
+	new->id = id;
+	new->callback = rx_cb;
+	new->pdev = pdev;
+
+	spin_lock_irqsave(&dln2->rx_cb_lock, flags);
+
+	list_for_each_entry(i, &dln2->rx_cb_list, list) {
+		if (i->id == id) {
+			ret = -EBUSY;
+			break;
+		}
+	}
+
+	if (!ret)
+		list_add(&new->list, &dln2->rx_cb_list);
+
+	spin_unlock_irqrestore(&dln2->rx_cb_lock, flags);
+
+	if (ret)
+		kfree(new);
+
+	return ret;
+}
+EXPORT_SYMBOL(dln2_register_event_cb);
+
+void dln2_unregister_event_cb(struct platform_device *pdev, u16 id)
+{
+	struct dln2_dev *dln2 = dev_get_drvdata(pdev->dev.parent);
+	struct dln2_rx_cb_entry *i, *tmp;
+	unsigned long flags;
+
+	spin_lock_irqsave(&dln2->rx_cb_lock, flags);
+
+	list_for_each_entry_safe(i, tmp, &dln2->rx_cb_list, list) {
+		if (i->id == id) {
+			list_del(&i->list);
+			kfree(i);
+		}
+	}
+
+	spin_unlock_irqrestore(&dln2->rx_cb_lock, flags);
+}
+EXPORT_SYMBOL(dln2_unregister_event_cb);
+
+static void dln2_rx_transfer(struct dln2_dev *dln2, struct urb *urb,
+			     u16 handle, u16 rx_slot)
+{
+	struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[handle];
+	struct dln2_rx_context *rxc;
+	struct device *dev = &dln2->interface->dev;
+	int err;
+
+	spin_lock(&rxs->lock);
+	rxc = &rxs->slots[rx_slot];
+	if (rxc->connected) {
+		rxc->urb = urb;
+		complete(&rxc->done);
+	} else {
+		dev_warn(dev, "dropping response %d/%d", handle, rx_slot);
+		err = usb_submit_urb(urb, GFP_ATOMIC);
+		if (err < 0)
+			dev_err(dev, "failed to re-submit RX URB: %d\n", err);
+	}
+	spin_unlock(&rxs->lock);
+}
+
+static void dln2_run_rx_callbacks(struct dln2_dev *dln2, u16 id, u16 echo,
+				  void *data, int len)
+{
+	struct dln2_rx_cb_entry *i;
+
+	spin_lock(&dln2->rx_cb_lock);
+
+	list_for_each_entry(i, &dln2->rx_cb_list, list)
+		if (i->id == id)
+			i->callback(i->pdev, echo, data, len);
+
+	spin_unlock(&dln2->rx_cb_lock);
+}
+
+static void dln2_rx(struct urb *urb)
+{
+	int err;
+	struct dln2_dev *dln2 = urb->context;
+	struct dln2_header *hdr = urb->transfer_buffer;
+	struct device *dev = &dln2->interface->dev;
+	u16 id, echo, handle, size;
+	u8 *data;
+	int len;
+
+	switch (urb->status) {
+	case 0:
+		/* success */
+		break;
+	case -ECONNRESET:
+	case -ENOENT:
+	case -ESHUTDOWN:
+	case -EPIPE:
+		/* this urb is terminated, clean up */
+		dev_dbg(dev, "urb shutting down with status %d\n", urb->status);
+		return;
+	default:
+		dev_dbg(dev, "nonzero urb status received %d\n", urb->status);
+		goto out;
+	}
+
+	if (urb->actual_length < sizeof(struct dln2_header)) {
+		dev_err(dev, "short response: %d\n", urb->actual_length);
+		goto out;
+	}
+
+	handle = le16_to_cpu(hdr->handle);
+	id = le16_to_cpu(hdr->id);
+	echo = le16_to_cpu(hdr->echo);
+	size = le16_to_cpu(hdr->size);
+
+	if (size != urb->actual_length) {
+		dev_err(dev, "size mismatch: handle %x cmd %x echo %x size %d actual %d\n",
+			handle, id, echo, size, urb->actual_length);
+		goto out;
+	}
+
+	if (handle >= DLN2_MAX_MODULES) {
+		dev_warn(dev, "RX: invalid handle %d\n", handle);
+		goto out;
+	}
+
+	data = urb->transfer_buffer + sizeof(struct dln2_header);
+	len = urb->actual_length - sizeof(struct dln2_header);
+
+	if (handle == DLN2_HANDLE_EVENT) {
+		dln2_run_rx_callbacks(dln2, id, echo, data, len);
+		err = usb_submit_urb(urb, GFP_ATOMIC);
+		if (err < 0)
+			goto out_submit_failed;
+	} else {
+		dln2_rx_transfer(dln2, urb, handle, echo);
+	}
+
+	return;
+
+out:
+	err = usb_submit_urb(urb, GFP_ATOMIC);
+out_submit_failed:
+	if (err < 0)
+		dev_err(dev, "failed to re-submit RX URB: %d\n", err);
+}
+
+static void *dln2_prep_buf(u16 handle, u16 cmd, u16 echo, const void *obuf,
+			   int *obuf_len, gfp_t gfp)
+{
+	int len;
+	void *buf;
+	struct dln2_header *hdr;
+
+	len = *obuf_len + sizeof(*hdr);
+	buf = kmalloc(len, gfp);
+	if (!buf)
+		return NULL;
+
+	hdr = (struct dln2_header *)buf;
+	hdr->id = cpu_to_le16(cmd);
+	hdr->size = cpu_to_le16(len);
+	hdr->echo = cpu_to_le16(echo);
+	hdr->handle = cpu_to_le16(handle);
+
+	memcpy(buf + sizeof(*hdr), obuf, *obuf_len);
+
+	*obuf_len = len;
+
+	return buf;
+}
+
+static int dln2_send_wait(struct dln2_dev *dln2, u16 handle, u16 cmd, u16 echo,
+			  const void *obuf, int obuf_len)
+{
+	int ret = 0;
+	int len = obuf_len;
+	void *buf;
+	int actual;
+
+	buf = dln2_prep_buf(handle, cmd, echo, obuf, &len, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = usb_bulk_msg(dln2->usb_dev,
+			   usb_sndbulkpipe(dln2->usb_dev, dln2->ep_out),
+			   buf, len, &actual, DLN2_USB_TIMEOUT);
+
+	kfree(buf);
+
+	return ret;
+}
+
+static int _dln2_transfer(struct dln2_dev *dln2, u16 handle, u16 cmd,
+			  const void *obuf, unsigned obuf_len,
+			  void *ibuf, unsigned *ibuf_len)
+{
+	int ret = 0;
+	u16 result;
+	int rx_slot;
+	struct dln2_response *rsp;
+	struct dln2_rx_context *rxc;
+	struct device *dev = &dln2->interface->dev;
+	const int timeout = DLN2_USB_TIMEOUT * HZ / 1000;
+	struct dln2_mod_rx_slots *rxs = &dln2->mod_rx_slots[handle];
+
+	rx_slot = alloc_rx_slot(rxs);
+	if (rx_slot < 0)
+		return rx_slot;
+
+	ret = dln2_send_wait(dln2, handle, cmd, rx_slot, obuf, obuf_len);
+	if (ret < 0) {
+		free_rx_slot(dln2, rxs, rx_slot);
+		dev_err(dev, "USB write failed: %d", ret);
+		return ret;
+	}
+
+	rxc = &rxs->slots[rx_slot];
+
+	ret = wait_for_completion_interruptible_timeout(&rxc->done, timeout);
+	if (ret <= 0) {
+		if (!ret)
+			ret = -ETIMEDOUT;
+		goto out_free_rx_slot;
+	}
+
+	/* if we got here we know that the response header has been checked */
+	rsp = rxc->urb->transfer_buffer;
+	if (rsp->hdr.size < sizeof(*rsp)) {
+		ret = -EPROTO;
+		goto out_free_rx_slot;
+	}
+
+	result = le16_to_cpu(rsp->result);
+	if (result) {
+		dev_dbg(dev, "%d received response with error %d\n",
+			handle, result);
+		ret = -EREMOTEIO;
+		goto out_free_rx_slot;
+	}
+
+	if (!ibuf) {
+		ret = 0;
+		goto out_free_rx_slot;
+	}
+
+	if (*ibuf_len > rsp->hdr.size - sizeof(*rsp))
+		*ibuf_len = rsp->hdr.size - sizeof(*rsp);
+
+	memcpy(ibuf, rsp + 1, *ibuf_len);
+
+out_free_rx_slot:
+	free_rx_slot(dln2, rxs, rx_slot);
+
+	return ret;
+}
+
+int dln2_transfer(struct platform_device *pdev, u16 cmd,
+		  const void *obuf, unsigned obuf_len,
+		  void *ibuf, unsigned *ibuf_len)
+{
+	struct dln2_platform_data *dln2_pdata;
+	struct dln2_dev *dln2;
+	u16 h;
+
+	/* USB device has been disconnected, bail out */
+	if (!pdev)
+		return -ENODEV;
+
+	dln2 = dev_get_drvdata(pdev->dev.parent);
+	dln2_pdata = dev_get_platdata(&pdev->dev);
+	h = dln2_pdata->handle;
+
+	return _dln2_transfer(dln2, h, cmd, obuf, obuf_len, ibuf, ibuf_len);
+}
+EXPORT_SYMBOL(dln2_transfer);
+
+static int dln2_check_hw(struct dln2_dev *dln2)
+{
+	int ret;
+	__le32 hw_type;
+	int len = sizeof(hw_type);
+
+	ret = _dln2_transfer(dln2, DLN2_HANDLE_CTRL, CMD_GET_DEVICE_VER,
+			     NULL, 0, &hw_type, &len);
+	if (ret < 0)
+		return ret;
+	if (len < sizeof(hw_type))
+		return -EREMOTEIO;
+
+	if (le32_to_cpu(hw_type) != DLN2_HW_ID) {
+		dev_err(&dln2->interface->dev, "Device ID 0x%x not supported",
+			le32_to_cpu(hw_type));
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+static int dln2_print_serialno(struct dln2_dev *dln2)
+{
+	int ret;
+	__le32 serial_no;
+	int len = sizeof(serial_no);
+	struct device *dev = &dln2->interface->dev;
+
+	ret = _dln2_transfer(dln2, DLN2_HANDLE_CTRL, CMD_GET_DEVICE_SN, NULL, 0,
+			     &serial_no, &len);
+	if (ret < 0)
+		return ret;
+	if (len < sizeof(serial_no))
+		return -EREMOTEIO;
+
+	dev_info(dev, "Diolan DLN2 serial 0x%x\n", le32_to_cpu(serial_no));
+
+	return 0;
+}
+
+static int dln2_hw_init(struct dln2_dev *dln2)
+{
+	int ret;
+
+	ret = dln2_check_hw(dln2);
+	if (ret < 0)
+		return ret;
+
+	return dln2_print_serialno(dln2);
+}
+
+static void dln2_free_rx_urbs(struct dln2_dev *dln2)
+{
+	int i;
+
+	for (i = 0; i < DLN2_MAX_URBS; i++) {
+		usb_kill_urb(dln2->rx_urb[i]);
+		usb_free_urb(dln2->rx_urb[i]);
+		kfree(dln2->rx_buf[i]);
+	}
+}
+
+static void dln2_free(struct dln2_dev *dln2)
+{
+	dln2_free_rx_urbs(dln2);
+	usb_put_dev(dln2->usb_dev);
+	kfree(dln2);
+}
+
+static int dln2_setup_rx_urbs(struct dln2_dev *dln2,
+			      struct usb_host_interface *hostif)
+{
+	int i;
+	const int rx_max_size = DLN2_RX_BUF_SIZE;
+	struct device *dev = &dln2->interface->dev;
+
+	for (i = 0; i < DLN2_MAX_URBS; i++) {
+		int ret;
+
+		dln2->rx_buf[i] = kmalloc(rx_max_size, GFP_KERNEL);
+		if (!dln2->rx_buf[i])
+			return -ENOMEM;
+
+		dln2->rx_urb[i] = usb_alloc_urb(0, GFP_KERNEL);
+		if (!dln2->rx_urb[i])
+			return -ENOMEM;
+
+		usb_fill_bulk_urb(dln2->rx_urb[i], dln2->usb_dev,
+				  usb_rcvbulkpipe(dln2->usb_dev, dln2->ep_in),
+				  dln2->rx_buf[i], rx_max_size, dln2_rx, dln2);
+
+		ret = usb_submit_urb(dln2->rx_urb[i], GFP_KERNEL);
+		if (ret < 0) {
+			dev_err(dev, "failed to submit RX URB: %d\n", ret);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+static struct dln2_platform_data dln2_pdata_gpio = {
+	.handle = DLN2_HANDLE_GPIO,
+};
+
+/* Right now only one I2C port seems to be supported */
+static struct dln2_platform_data dln2_pdata_i2c = {
+	.handle = DLN2_HANDLE_I2C,
+	.i2c = {
+		.port = 0,
+	},
+};
+
+static const struct mfd_cell dln2_devs[] = {
+	{
+		.name	= "dln2-gpio",
+		.platform_data = &dln2_pdata_gpio,
+		.pdata_size = sizeof(struct dln2_platform_data),
+	},
+	{
+		.name	= "dln2-i2c",
+		.platform_data = &dln2_pdata_i2c,
+		.pdata_size = sizeof(struct dln2_platform_data),
+	},
+};
+
+static void dln2_disconnect(struct usb_interface *interface)
+{
+	struct dln2_dev *dln2 = usb_get_intfdata(interface);
+
+	mfd_remove_devices(&interface->dev);
+	dln2_free(dln2);
+}
+
+static int dln2_probe(struct usb_interface *interface,
+		      const struct usb_device_id *id)
+{
+	struct usb_host_interface *hostif = interface->cur_altsetting;
+	struct device *dev = &interface->dev;
+	struct dln2_dev *dln2;
+	int ret;
+	int i, j;
+
+	if (hostif->desc.bInterfaceNumber != 0 ||
+	    hostif->desc.bNumEndpoints < 2)
+		return -ENODEV;
+
+	dln2 = kzalloc(sizeof(*dln2), GFP_KERNEL);
+	if (!dln2)
+		return -ENOMEM;
+
+	dln2->ep_out = hostif->endpoint[0].desc.bEndpointAddress;
+	dln2->ep_in = hostif->endpoint[1].desc.bEndpointAddress;
+	dln2->usb_dev = usb_get_dev(interface_to_usbdev(interface));
+	dln2->interface = interface;
+	usb_set_intfdata(interface, dln2);
+
+	for (i = 0; i < DLN2_MAX_MODULES; i++) {
+		init_waitqueue_head(&dln2->mod_rx_slots[i].wq);
+		spin_lock_init(&dln2->mod_rx_slots[i].lock);
+		for (j = 0; j < DLN2_MAX_RX_SLOTS; j++)
+			init_completion(&dln2->mod_rx_slots[i].slots[j].done);
+	}
+
+	spin_lock_init(&dln2->rx_cb_lock);
+	INIT_LIST_HEAD(&dln2->rx_cb_list);
+
+	ret = dln2_setup_rx_urbs(dln2, hostif);
+	if (ret) {
+		dln2_free(dln2);
+		return ret;
+	}
+
+	ret = dln2_hw_init(dln2);
+	if (ret < 0) {
+		dev_err(dev, "failed to initialize hardware\n");
+		goto out_cleanup;
+	}
+
+	ret = mfd_add_devices(dev, -1, dln2_devs, ARRAY_SIZE(dln2_devs),
+			      NULL, 0, NULL);
+	if (ret != 0) {
+		dev_err(dev, "Failed to add mfd devices to core.\n");
+		goto out_cleanup;
+	}
+
+	return 0;
+
+out_cleanup:
+	dln2_free(dln2);
+
+	return ret;
+}
+
+static const struct usb_device_id dln2_table[] = {
+	{ USB_DEVICE(0xa257, 0x2013) },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(usb, dln2_table);
+
+static struct usb_driver dln2_driver = {
+	.name = DRIVER_NAME,
+	.probe = dln2_probe,
+	.disconnect = dln2_disconnect,
+	.id_table = dln2_table,
+};
+
+module_usb_driver(dln2_driver);
+
+MODULE_AUTHOR("Octavian Purdila <octavian.purdila@intel.com>");
+MODULE_DESCRIPTION(DRIVER_NAME " driver");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/mfd/dln2.h b/include/linux/mfd/dln2.h
new file mode 100644
index 0000000..197565d
--- /dev/null
+++ b/include/linux/mfd/dln2.h
@@ -0,0 +1,71 @@ 
+#ifndef __LINUX_USB_DLN2_H
+#define __LINUX_USB_DLN2_H
+
+#define DLN2_CMD(cmd, id)		((cmd) | ((id) << 8))
+
+struct dln2_platform_data {
+	u16 handle;
+	union {
+		struct {
+			u8 port;
+		} i2c;
+	};
+};
+
+/**
+ * dln2_rx_cb - event callback function signature
+ *
+ * @pdev - the sub-device that registered this callback
+ * @echo - the echo header field received in the message
+ * @data - the data payload
+ * @len  - the data payload length
+ *
+ * The callback function is called in interrupt context and the data
+ * payload is only valid during the call. If the user needs later
+ * access of the data, it must copy it.
+ */
+
+typedef void (*dln2_rx_cb_t)(struct platform_device *pdev, u16 echo,
+			     const void *data, int len);
+
+/**
+ * dl2n_register_event_cb - register a callback function for an event
+ *
+ * @pdev - the sub-device that registers the callback
+ * @event - the event for which to register a callback
+ * @rx_cb - the callback function
+ *
+ * @return 0 in case of success, negative value in case of error
+ */
+int dln2_register_event_cb(struct platform_device *pdev, u16 event,
+			   dln2_rx_cb_t rx_cb);
+
+/**
+ * dln2_unregister_event_cb - unregister the callback function for an event
+ *
+ * @pdev - the sub-device that registered the callback
+ * @event - the event for which to register a callback
+ */
+void dln2_unregister_event_cb(struct platform_device *pdev, u16 event);
+
+/**
+ * dln2_transfer - issue a DLN2 command and wait for a response and
+ * the associated data
+ *
+ * @pdev - the sub-device which is issuing this transfer
+ * @cmd - the command to be sent to the device
+ * @obuf - the buffer to be sent to the device; can be NULL if the
+ * user doesn't need to transmit data with this command
+ * @obuf_len - the size of the buffer to be sent to the device
+ * @ibuf - any data associated with the response will be copied here;
+ * it can be NULL if the user doesn't need the response data
+ * @ibuf_len - must be initialized to the input buffer size; it will
+ * be modified to indicate the actual data transfered
+ *
+ * @returns 0 for success, negative value for errors
+ */
+int dln2_transfer(struct platform_device *pdev, u16 cmd,
+		  const void *obuf, unsigned obuf_len,
+		  void *ibuf, unsigned *ibuf_len);
+
+#endif