[v4,1/2] hwmon: lochnagar: Add device tree binding document

Lochnagar is an evaluation and development board for Cirrus
Logic Smart CODEC and Amp devices. It allows the connection of
most Cirrus Logic devices on mini-cards, as well as allowing
connection of various application processor systems to provide a
full evaluation platform. This driver supports the board
controller chip on the Lochnagar board.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
---

No changes since v3.

Thanks,
Charles

 .../devicetree/bindings/hwmon/cirrus,lochnagar.txt | 26 ++++++++++++++++++++++
 1 file changed, 26 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/cirrus,lochnagar.txt

On Thu, Mar 28, 2019 at 01:09:36PM +0000, Charles Keepax wrote:
> Lochnagar is an evaluation and development board for Cirrus
> Logic Smart CODEC and Amp devices. It allows the connection of
> most Cirrus Logic devices on mini-cards, as well as allowing
> connection of various application processor systems to provide a
> full evaluation platform. This driver supports the board
> controller chip on the Lochnagar board.
> 
> Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
> ---
> 
> No changes since v3.
> 
> Thanks,
> Charles
> 
>  .../devicetree/bindings/hwmon/cirrus,lochnagar.txt | 26 ++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/hwmon/cirrus,lochnagar.txt
> 
> diff --git a/Documentation/devicetree/bindings/hwmon/cirrus,lochnagar.txt b/Documentation/devicetree/bindings/hwmon/cirrus,lochnagar.txt
> new file mode 100644
> index 0000000000000..ffb79ccf51ee3
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwmon/cirrus,lochnagar.txt
> @@ -0,0 +1,26 @@
> +Cirrus Logic Lochnagar Audio Development Board
> +
> +Lochnagar is an evaluation and development board for Cirrus Logic
> +Smart CODEC and Amp devices. It allows the connection of most Cirrus
> +Logic devices on mini-cards, as well as allowing connection of
> +various application processor systems to provide a full evaluation
> +platform.  Audio system topology, clocking and power can all be
> +controlled through the Lochnagar, allowing the device under test
> +to be used in a variety of possible use cases.
> +
> +This binding document describes the binding for the hardware monitor
> +portion of the driver.
> +
> +This binding must be part of the Lochnagar MFD binding:
> +  [4] ../mfd/cirrus,lochnagar.txt
> +
> +Required properties:
> +
> +  - compatible : One of the following strings:
> +                 "cirrus,lochnagar2-hwmon"
> +
> +Example:
> +
> +lochnagar-hwmon {
> +	compatible = "cirrus,lochnagar2-hwmon";

You don't have any resources in DT, the parent MFD driver can just 
instantiate this child device.

Rob

On Thu, Mar 28, 2019 at 12:46:15PM -0500, Rob Herring wrote:
> On Thu, Mar 28, 2019 at 01:09:36PM +0000, Charles Keepax wrote:
> > Lochnagar is an evaluation and development board for Cirrus
> > Logic Smart CODEC and Amp devices. It allows the connection of
> > most Cirrus Logic devices on mini-cards, as well as allowing
> > connection of various application processor systems to provide a
> > full evaluation platform. This driver supports the board
> > controller chip on the Lochnagar board.
> > 
> > Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
> > ---
> > +Required properties:
> > +
> > +  - compatible : One of the following strings:
> > +                 "cirrus,lochnagar2-hwmon"
> > +
> > +Example:
> > +
> > +lochnagar-hwmon {
> > +	compatible = "cirrus,lochnagar2-hwmon";
> 
> You don't have any resources in DT, the parent MFD driver can just 
> instantiate this child device.
> 

+ Lee Jones

Lee, was very very keen for me to not mix mfd_add_devices and
of_platform_populate in the MFD driver. As such we moved all the
sub-drivers into DT. I agree it is a little odd that this exists
only to bind in this driver but I think it is probably a bit late
to change that. If we were going to have the MFD instantiating
children directly a lot of the rest of the binding would have
been done very differently.

Thanks,
Charles

On Fri, Mar 29, 2019 at 4:22 AM Charles Keepax
<ckeepax@opensource.cirrus.com> wrote:
>
> On Thu, Mar 28, 2019 at 12:46:15PM -0500, Rob Herring wrote:
> > On Thu, Mar 28, 2019 at 01:09:36PM +0000, Charles Keepax wrote:
> > > Lochnagar is an evaluation and development board for Cirrus
> > > Logic Smart CODEC and Amp devices. It allows the connection of
> > > most Cirrus Logic devices on mini-cards, as well as allowing
> > > connection of various application processor systems to provide a
> > > full evaluation platform. This driver supports the board
> > > controller chip on the Lochnagar board.
> > >
> > > Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
> > > ---
> > > +Required properties:
> > > +
> > > +  - compatible : One of the following strings:
> > > +                 "cirrus,lochnagar2-hwmon"
> > > +
> > > +Example:
> > > +
> > > +lochnagar-hwmon {
> > > +   compatible = "cirrus,lochnagar2-hwmon";
> >
> > You don't have any resources in DT, the parent MFD driver can just
> > instantiate this child device.
> >
>
> + Lee Jones
>
> Lee, was very very keen for me to not mix mfd_add_devices and
> of_platform_populate in the MFD driver. As such we moved all the
> sub-drivers into DT. I agree it is a little odd that this exists
> only to bind in this driver but I think it is probably a bit late
> to change that. If we were going to have the MFD instantiating
> children directly a lot of the rest of the binding would have
> been done very differently.

Okay. This is why I don't like incomplete examples...

Reviewed-by: Rob Herring <robh@kernel.org>

On Fri, Mar 29, 2019 at 08:28:35AM -0500, Rob Herring wrote:
> On Fri, Mar 29, 2019 at 4:22 AM Charles Keepax
> <ckeepax@opensource.cirrus.com> wrote:
> > On Thu, Mar 28, 2019 at 12:46:15PM -0500, Rob Herring wrote:
> > > On Thu, Mar 28, 2019 at 01:09:36PM +0000, Charles Keepax wrote:
> > > > Lochnagar is an evaluation and development board for Cirrus
> > > > Logic Smart CODEC and Amp devices. It allows the connection of
> > > > most Cirrus Logic devices on mini-cards, as well as allowing
> > > > connection of various application processor systems to provide a
> > > > full evaluation platform. This driver supports the board
> > > > controller chip on the Lochnagar board.
> > > >
> > > > Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
> > > > ---
> > > > +Example:
> > > > +
> > > > +lochnagar-hwmon {
> > > > +   compatible = "cirrus,lochnagar2-hwmon";
> > >
> > > You don't have any resources in DT, the parent MFD driver can just
> > > instantiate this child device.
> > >
> >
> > + Lee Jones
> >
> > Lee, was very very keen for me to not mix mfd_add_devices and
> > of_platform_populate in the MFD driver. As such we moved all the
> > sub-drivers into DT. I agree it is a little odd that this exists
> > only to bind in this driver but I think it is probably a bit late
> > to change that. If we were going to have the MFD instantiating
> > children directly a lot of the rest of the binding would have
> > been done very differently.
> 
> Okay. This is why I don't like incomplete examples...
> 
> Reviewed-by: Rob Herring <robh@kernel.org>

Thank you, and apologies for that. I do not think it will
always be possible to include all the functionality in the
first sending, certainly from a code perspective. But we could
look at least to include some stubs/as much as we can foresee in
the binding document. Would that be the sort of direction you
had in mind?

Thanks,
Charles

On Thu, Mar 28, 2019 at 01:09:36PM +0000, Charles Keepax wrote:
> Lochnagar is an evaluation and development board for Cirrus
> Logic Smart CODEC and Amp devices. It allows the connection of
> most Cirrus Logic devices on mini-cards, as well as allowing
> connection of various application processor systems to provide a
> full evaluation platform. This driver supports the board
> controller chip on the Lochnagar board.
> 
> Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
> Reviewed-by: Rob Herring <robh@kernel.org>

Applied to hwmon-next.

Thanks,
Guenter

> ---
> 
> No changes since v3.
> 
> Thanks,
> Charles
> 
>  .../devicetree/bindings/hwmon/cirrus,lochnagar.txt | 26 ++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/hwmon/cirrus,lochnagar.txt
> 
> diff --git a/Documentation/devicetree/bindings/hwmon/cirrus,lochnagar.txt b/Documentation/devicetree/bindings/hwmon/cirrus,lochnagar.txt
> new file mode 100644
> index 0000000000000..ffb79ccf51ee3
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwmon/cirrus,lochnagar.txt
> @@ -0,0 +1,26 @@
> +Cirrus Logic Lochnagar Audio Development Board
> +
> +Lochnagar is an evaluation and development board for Cirrus Logic
> +Smart CODEC and Amp devices. It allows the connection of most Cirrus
> +Logic devices on mini-cards, as well as allowing connection of
> +various application processor systems to provide a full evaluation
> +platform.  Audio system topology, clocking and power can all be
> +controlled through the Lochnagar, allowing the device under test
> +to be used in a variety of possible use cases.
> +
> +This binding document describes the binding for the hardware monitor
> +portion of the driver.
> +
> +This binding must be part of the Lochnagar MFD binding:
> +  [4] ../mfd/cirrus,lochnagar.txt
> +
> +Required properties:
> +
> +  - compatible : One of the following strings:
> +                 "cirrus,lochnagar2-hwmon"
> +
> +Example:
> +
> +lochnagar-hwmon {
> +	compatible = "cirrus,lochnagar2-hwmon";
> +};

On Thu, Mar 28, 2019 at 01:09:37PM +0000, Charles Keepax wrote:
> From: Lucas Tanure <tanureal@opensource.cirrus.com>
> 
> Lochnagar is an evaluation and development board for Cirrus
> Logic Smart CODEC and Amp devices. It allows the connection of
> most Cirrus Logic devices on mini-cards, as well as allowing
> connection of various application processor systems to provide a
> full evaluation platform.
> 
> This driver adds support for the hardware monitoring features of
> the Lochnagar 2 to the hwmon API. Monitoring is provided for
> the board voltages, currents and temperature supported by the
> board controller chip.
> 
> Signed-off-by: Lucas Tanure <tanureal@opensource.cirrus.com>
> Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>

Applied to hwmon-next.

Thanks,
Guenter

> ---
> 
> Changes since v3:
>  - Add defines for the precision of each measurement
>  - Change to storing number of samples for averaging not time
>  - Use DIV_ROUND_CLOSEST_ULL
> 
> Thanks,
> Charles
> 
>  Documentation/hwmon/lochnagar   |  80 ++++++++
>  MAINTAINERS                     |   3 +
>  drivers/hwmon/Kconfig           |  10 +
>  drivers/hwmon/Makefile          |   1 +
>  drivers/hwmon/lochnagar-hwmon.c | 412 ++++++++++++++++++++++++++++++++++++++++
>  5 files changed, 506 insertions(+)
>  create mode 100644 Documentation/hwmon/lochnagar
>  create mode 100644 drivers/hwmon/lochnagar-hwmon.c
> 
> diff --git a/Documentation/hwmon/lochnagar b/Documentation/hwmon/lochnagar
> new file mode 100644
> index 0000000000000..e9686fb3eb405
> --- /dev/null
> +++ b/Documentation/hwmon/lochnagar
> @@ -0,0 +1,80 @@
> +Kernel Driver Lochnagar
> +========================
> +
> +Supported systems:
> +  * Cirrus Logic : Lochnagar 2
> +
> +Author: Lucas A. Tanure Alves
> +
> +Description
> +-----------
> +
> +Lochnagar 2 features built-in Current Monitor circuitry that allows for the
> +measurement of both voltage and current on up to eight of the supply voltage
> +rails provided to the minicards. The Current Monitor does not require any
> +hardware modifications or external circuitry to operate.
> +
> +The current and voltage measurements are obtained through the standard register
> +map interface to the Lochnagar board controller, and can therefore be monitored
> +by software.
> +
> +Sysfs attributes
> +----------------
> +
> +temp1_input             The Lochnagar board temperature (milliCelsius)
> +in0_input               Measured voltage for DBVDD1 (milliVolts)
> +in0_label               "DBVDD1"
> +curr1_input             Measured current for DBVDD1 (milliAmps)
> +curr1_label             "DBVDD1"
> +power1_average          Measured average power for DBVDD1 (microWatts)
> +power1_average_interval Power averaging time input valid from 1 to 1708mS
> +power1_label            "DBVDD1"
> +in1_input               Measured voltage for 1V8 DSP (milliVolts)
> +in1_label               "1V8 DSP"
> +curr2_input             Measured current for 1V8 DSP (milliAmps)
> +curr2_label             "1V8 DSP"
> +power2_average          Measured average power for 1V8 DSP (microWatts)
> +power2_average_interval Power averaging time input valid from 1 to 1708mS
> +power2_label            "1V8 DSP"
> +in2_input               Measured voltage for 1V8 CDC (milliVolts)
> +in2_label               "1V8 CDC"
> +curr3_input             Measured current for 1V8 CDC (milliAmps)
> +curr3_label             "1V8 CDC"
> +power3_average          Measured average power for 1V8 CDC (microWatts)
> +power3_average_interval Power averaging time input valid from 1 to 1708mS
> +power3_label            "1V8 CDC"
> +in3_input               Measured voltage for VDDCORE DSP (milliVolts)
> +in3_label               "VDDCORE DSP"
> +curr4_input             Measured current for VDDCORE DSP (milliAmps)
> +curr4_label             "VDDCORE DSP"
> +power4_average          Measured average power for VDDCORE DSP (microWatts)
> +power4_average_interval Power averaging time input valid from 1 to 1708mS
> +power4_label            "VDDCORE DSP"
> +in4_input               Measured voltage for AVDD 1V8 (milliVolts)
> +in4_label               "AVDD 1V8"
> +curr5_input             Measured current for AVDD 1V8 (milliAmps)
> +curr5_label             "AVDD 1V8"
> +power5_average          Measured average power for AVDD 1V8 (microWatts)
> +power5_average_interval Power averaging time input valid from 1 to 1708mS
> +power5_label            "AVDD 1V8"
> +curr6_input             Measured current for SYSVDD (milliAmps)
> +curr6_label             "SYSVDD"
> +power6_average          Measured average power for SYSVDD (microWatts)
> +power6_average_interval Power averaging time input valid from 1 to 1708mS
> +power6_label            "SYSVDD"
> +in6_input               Measured voltage for VDDCORE CDC (milliVolts)
> +in6_label               "VDDCORE CDC"
> +curr7_input             Measured current for VDDCORE CDC (milliAmps)
> +curr7_label             "VDDCORE CDC"
> +power7_average          Measured average power for VDDCORE CDC (microWatts)
> +power7_average_interval Power averaging time input valid from 1 to 1708mS
> +power7_label            "VDDCORE CDC"
> +in7_input               Measured voltage for MICVDD (milliVolts)
> +in7_label               "MICVDD"
> +curr8_input             Measured current for MICVDD (milliAmps)
> +curr8_label             "MICVDD"
> +power8_average          Measured average power for MICVDD (microWatts)
> +power8_average_interval Power averaging time input valid from 1 to 1708mS
> +power8_label            "MICVDD"
> +
> +Note: It is not possible to measure voltage on the SYSVDD rail.
> diff --git a/MAINTAINERS b/MAINTAINERS
> index e17ebf70b5480..4cd3c281d8b56 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -3796,6 +3796,7 @@ M:	Richard Fitzgerald <rf@opensource.cirrus.com>
>  L:	patches@opensource.cirrus.com
>  S:	Supported
>  F:	drivers/clk/clk-lochnagar.c
> +F:	drivers/hwmon/lochnagar-hwmon.c
>  F:	drivers/mfd/lochnagar-i2c.c
>  F:	drivers/pinctrl/cirrus/pinctrl-lochnagar.c
>  F:	drivers/regulator/lochnagar-regulator.c
> @@ -3804,8 +3805,10 @@ F:	include/dt-bindings/pinctrl/lochnagar.h
>  F:	include/linux/mfd/lochnagar*
>  F:	Documentation/devicetree/bindings/mfd/cirrus,lochnagar.txt
>  F:	Documentation/devicetree/bindings/clock/cirrus,lochnagar.txt
> +F:	Documentation/devicetree/bindings/hwmon/cirrus,lochnagar.txt
>  F:	Documentation/devicetree/bindings/pinctrl/cirrus,lochnagar.txt
>  F:	Documentation/devicetree/bindings/regulator/cirrus,lochnagar.txt
> +F:	Documentation/hwmon/lochnagar
>  
>  CISCO FCOE HBA DRIVER
>  M:	Satish Kharat <satishkh@cisco.com>
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index d0f1dfe2bcbbd..dedd5febd3aa6 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -705,6 +705,16 @@ config SENSORS_LINEAGE
>  	  This driver can also be built as a module. If so, the module
>  	  will be called lineage-pem.
>  
> +config SENSORS_LOCHNAGAR
> +	tristate "Lochnagar Hardware Monitor"
> +	depends on MFD_LOCHNAGAR
> +	help
> +	  If you say yes here you get support for Lochnagar 2 temperature,
> +	  voltage and current sensors abilities.
> +
> +	  This driver can also be built as a module.  If so, the module
> +	  will be called lochnagar-hwmon.
> +
>  config SENSORS_LTC2945
>  	tristate "Linear Technology LTC2945"
>  	depends on I2C
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index f5c7b442e69e5..8db472ea04f00 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -89,6 +89,7 @@ obj-$(CONFIG_SENSORS_JZ4740)	+= jz4740-hwmon.o
>  obj-$(CONFIG_SENSORS_K8TEMP)	+= k8temp.o
>  obj-$(CONFIG_SENSORS_K10TEMP)	+= k10temp.o
>  obj-$(CONFIG_SENSORS_LINEAGE)	+= lineage-pem.o
> +obj-$(CONFIG_SENSORS_LOCHNAGAR)	+= lochnagar-hwmon.o
>  obj-$(CONFIG_SENSORS_LM63)	+= lm63.o
>  obj-$(CONFIG_SENSORS_LM70)	+= lm70.o
>  obj-$(CONFIG_SENSORS_LM73)	+= lm73.o
> diff --git a/drivers/hwmon/lochnagar-hwmon.c b/drivers/hwmon/lochnagar-hwmon.c
> new file mode 100644
> index 0000000000000..8b19adf2eeb07
> --- /dev/null
> +++ b/drivers/hwmon/lochnagar-hwmon.c
> @@ -0,0 +1,412 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Lochnagar hardware monitoring features
> + *
> + * Copyright (c) 2016-2019 Cirrus Logic, Inc. and
> + *                         Cirrus Logic International Semiconductor Ltd.
> + *
> + * Author: Lucas Tanure <tanureal@opensource.cirrus.com>
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/hwmon.h>
> +#include <linux/hwmon-sysfs.h>
> +#include <linux/i2c.h>
> +#include <linux/math64.h>
> +#include <linux/mfd/lochnagar.h>
> +#include <linux/mfd/lochnagar2_regs.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +
> +#define LN2_MAX_NSAMPLE 1023
> +#define LN2_SAMPLE_US   1670
> +
> +#define LN2_CURR_UNITS  1000
> +#define LN2_VOLT_UNITS  1000
> +#define LN2_TEMP_UNITS  1000
> +#define LN2_PWR_UNITS   1000000
> +
> +static const char * const lochnagar_chan_names[] = {
> +	"DBVDD1",
> +	"1V8 DSP",
> +	"1V8 CDC",
> +	"VDDCORE DSP",
> +	"AVDD 1V8",
> +	"SYSVDD",
> +	"VDDCORE CDC",
> +	"MICVDD",
> +};
> +
> +struct lochnagar_hwmon {
> +	struct regmap *regmap;
> +
> +	long power_nsamples[ARRAY_SIZE(lochnagar_chan_names)];
> +
> +	/* Lock to ensure only a single sensor is read at a time */
> +	struct mutex sensor_lock;
> +};
> +
> +enum lochnagar_measure_mode {
> +	LN2_CURR = 0,
> +	LN2_VOLT,
> +	LN2_TEMP,
> +};
> +
> +/**
> + * float_to_long - Convert ieee754 reading from hardware to an integer
> + *
> + * @data: Value read from the hardware
> + * @precision: Units to multiply up to eg. 1000 = milli, 1000000 = micro
> + *
> + * Return: Converted integer reading
> + *
> + * Depending on the measurement type the hardware returns an ieee754
> + * floating point value in either volts, amps or celsius. This function
> + * will convert that into an integer in a smaller unit such as micro-amps
> + * or milli-celsius. The hardware does not return NaN, so consideration of
> + * that is not required.
> + */
> +static long float_to_long(u32 data, u32 precision)
> +{
> +	u64 man = data & 0x007FFFFF;
> +	int exp = ((data & 0x7F800000) >> 23) - 127 - 23;
> +	bool negative = data & 0x80000000;
> +	long result;
> +
> +	man = (man + (1 << 23)) * precision;
> +
> +	if (fls64(man) + exp > (int)sizeof(long) * 8 - 1)
> +		result = LONG_MAX;
> +	else if (exp < 0)
> +		result = (man + (1ull << (-exp - 1))) >> -exp;
> +	else
> +		result = man << exp;
> +
> +	return negative ? -result : result;
> +}
> +
> +static int do_measurement(struct regmap *regmap, int chan,
> +			  enum lochnagar_measure_mode mode, int nsamples)
> +{
> +	unsigned int val;
> +	int ret;
> +
> +	chan = 1 << (chan + LOCHNAGAR2_IMON_MEASURED_CHANNELS_SHIFT);
> +
> +	ret = regmap_write(regmap, LOCHNAGAR2_IMON_CTRL1,
> +			   LOCHNAGAR2_IMON_ENA_MASK | chan | mode);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_write(regmap, LOCHNAGAR2_IMON_CTRL2, nsamples);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_write(regmap, LOCHNAGAR2_IMON_CTRL3,
> +			   LOCHNAGAR2_IMON_CONFIGURE_MASK);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret =  regmap_read_poll_timeout(regmap, LOCHNAGAR2_IMON_CTRL3, val,
> +					val & LOCHNAGAR2_IMON_DONE_MASK,
> +					1000, 10000);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_write(regmap, LOCHNAGAR2_IMON_CTRL3,
> +			   LOCHNAGAR2_IMON_MEASURE_MASK);
> +	if (ret < 0)
> +		return ret;
> +
> +	/*
> +	 * Actual measurement time is ~1.67mS per sample, approximate this
> +	 * with a 1.5mS per sample msleep and then poll for success up to
> +	 * ~0.17mS * 1023 (LN2_MAX_NSAMPLES). Normally for smaller values
> +	 * of nsamples the poll will complete on the first loop due to
> +	 * other latency in the system.
> +	 */
> +	msleep((nsamples * 3) / 2);
> +
> +	ret =  regmap_read_poll_timeout(regmap, LOCHNAGAR2_IMON_CTRL3, val,
> +					val & LOCHNAGAR2_IMON_DONE_MASK,
> +					5000, 200000);
> +	if (ret < 0)
> +		return ret;
> +
> +	return regmap_write(regmap, LOCHNAGAR2_IMON_CTRL3, 0);
> +}
> +
> +static int request_data(struct regmap *regmap, int chan, u32 *data)
> +{
> +	unsigned int val;
> +	int ret;
> +
> +	ret = regmap_write(regmap, LOCHNAGAR2_IMON_CTRL4,
> +			   LOCHNAGAR2_IMON_DATA_REQ_MASK |
> +			   chan << LOCHNAGAR2_IMON_CH_SEL_SHIFT);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret =  regmap_read_poll_timeout(regmap, LOCHNAGAR2_IMON_CTRL4, val,
> +					val & LOCHNAGAR2_IMON_DATA_RDY_MASK,
> +					1000, 10000);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_read(regmap, LOCHNAGAR2_IMON_DATA1, &val);
> +	if (ret < 0)
> +		return ret;
> +
> +	*data = val << 16;
> +
> +	ret = regmap_read(regmap, LOCHNAGAR2_IMON_DATA2, &val);
> +	if (ret < 0)
> +		return ret;
> +
> +	*data |= val;
> +
> +	return regmap_write(regmap, LOCHNAGAR2_IMON_CTRL4, 0);
> +}
> +
> +static int read_sensor(struct device *dev, int chan,
> +		       enum lochnagar_measure_mode mode, int nsamples,
> +		       unsigned int precision, long *val)
> +{
> +	struct lochnagar_hwmon *priv = dev_get_drvdata(dev);
> +	struct regmap *regmap = priv->regmap;
> +	u32 data;
> +	int ret;
> +
> +	mutex_lock(&priv->sensor_lock);
> +
> +	ret = do_measurement(regmap, chan, mode, nsamples);
> +	if (ret < 0) {
> +		dev_err(dev, "Failed to perform measurement: %d\n", ret);
> +		goto error;
> +	}
> +
> +	ret = request_data(regmap, chan, &data);
> +	if (ret < 0) {
> +		dev_err(dev, "Failed to read measurement: %d\n", ret);
> +		goto error;
> +	}
> +
> +	*val = float_to_long(data, precision);
> +
> +error:
> +	mutex_unlock(&priv->sensor_lock);
> +
> +	return ret;
> +}
> +
> +static int read_power(struct device *dev, int chan, long *val)
> +{
> +	struct lochnagar_hwmon *priv = dev_get_drvdata(dev);
> +	int nsamples = priv->power_nsamples[chan];
> +	u64 power;
> +	int ret;
> +
> +	if (!strcmp("SYSVDD", lochnagar_chan_names[chan])) {
> +		power = 5 * LN2_PWR_UNITS;
> +	} else {
> +		ret = read_sensor(dev, chan, LN2_VOLT, 1, LN2_PWR_UNITS, val);
> +		if (ret < 0)
> +			return ret;
> +
> +		power = abs(*val);
> +	}
> +
> +	ret = read_sensor(dev, chan, LN2_CURR, nsamples, LN2_PWR_UNITS, val);
> +	if (ret < 0)
> +		return ret;
> +
> +	power *= abs(*val);
> +	power = DIV_ROUND_CLOSEST_ULL(power, LN2_PWR_UNITS);
> +
> +	if (power > LONG_MAX)
> +		*val = LONG_MAX;
> +	else
> +		*val = power;
> +
> +	return 0;
> +}
> +
> +static umode_t lochnagar_is_visible(const void *drvdata,
> +				    enum hwmon_sensor_types type,
> +				    u32 attr, int chan)
> +{
> +	switch (type) {
> +	case hwmon_in:
> +		if (!strcmp("SYSVDD", lochnagar_chan_names[chan]))
> +			return 0;
> +		break;
> +	case hwmon_power:
> +		if (attr == hwmon_power_average_interval)
> +			return 0644;
> +		break;
> +	default:
> +		break;
> +	}
> +
> +	return 0444;
> +}
> +
> +static int lochnagar_read(struct device *dev, enum hwmon_sensor_types type,
> +			  u32 attr, int chan, long *val)
> +{
> +	struct lochnagar_hwmon *priv = dev_get_drvdata(dev);
> +	int interval;
> +
> +	switch (type) {
> +	case hwmon_in:
> +		return read_sensor(dev, chan, LN2_VOLT, 1, LN2_VOLT_UNITS, val);
> +	case hwmon_curr:
> +		return read_sensor(dev, chan, LN2_CURR, 1, LN2_CURR_UNITS, val);
> +	case hwmon_temp:
> +		return read_sensor(dev, chan, LN2_TEMP, 1, LN2_TEMP_UNITS, val);
> +	case hwmon_power:
> +		switch (attr) {
> +		case hwmon_power_average:
> +			return read_power(dev, chan, val);
> +		case hwmon_power_average_interval:
> +			interval = priv->power_nsamples[chan] * LN2_SAMPLE_US;
> +			*val = DIV_ROUND_CLOSEST(interval, 1000);
> +			return 0;
> +		default:
> +			return -EOPNOTSUPP;
> +		}
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static int lochnagar_read_string(struct device *dev,
> +				 enum hwmon_sensor_types type, u32 attr,
> +				 int chan, const char **str)
> +{
> +	switch (type) {
> +	case hwmon_in:
> +	case hwmon_curr:
> +	case hwmon_power:
> +		*str = lochnagar_chan_names[chan];
> +		return 0;
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static int lochnagar_write(struct device *dev, enum hwmon_sensor_types type,
> +			   u32 attr, int chan, long val)
> +{
> +	struct lochnagar_hwmon *priv = dev_get_drvdata(dev);
> +
> +	if (type != hwmon_power || attr != hwmon_power_average_interval)
> +		return -EOPNOTSUPP;
> +
> +	val = clamp_t(long, val, 1, (LN2_MAX_NSAMPLE * LN2_SAMPLE_US) / 1000);
> +	val = DIV_ROUND_CLOSEST(val * 1000, LN2_SAMPLE_US);
> +
> +	priv->power_nsamples[chan] = val;
> +
> +	return 0;
> +}
> +
> +static const struct hwmon_ops lochnagar_ops = {
> +	.is_visible = lochnagar_is_visible,
> +	.read = lochnagar_read,
> +	.read_string = lochnagar_read_string,
> +	.write = lochnagar_write,
> +};
> +
> +static const struct hwmon_channel_info *lochnagar_info[] = {
> +	HWMON_CHANNEL_INFO(temp,  HWMON_T_INPUT),
> +	HWMON_CHANNEL_INFO(in,    HWMON_I_INPUT | HWMON_I_LABEL,
> +				  HWMON_I_INPUT | HWMON_I_LABEL,
> +				  HWMON_I_INPUT | HWMON_I_LABEL,
> +				  HWMON_I_INPUT | HWMON_I_LABEL,
> +				  HWMON_I_INPUT | HWMON_I_LABEL,
> +				  HWMON_I_INPUT | HWMON_I_LABEL,
> +				  HWMON_I_INPUT | HWMON_I_LABEL,
> +				  HWMON_I_INPUT | HWMON_I_LABEL),
> +	HWMON_CHANNEL_INFO(curr,  HWMON_C_INPUT | HWMON_C_LABEL,
> +				  HWMON_C_INPUT | HWMON_C_LABEL,
> +				  HWMON_C_INPUT | HWMON_C_LABEL,
> +				  HWMON_C_INPUT | HWMON_C_LABEL,
> +				  HWMON_C_INPUT | HWMON_C_LABEL,
> +				  HWMON_C_INPUT | HWMON_C_LABEL,
> +				  HWMON_C_INPUT | HWMON_C_LABEL,
> +				  HWMON_C_INPUT | HWMON_C_LABEL),
> +	HWMON_CHANNEL_INFO(power, HWMON_P_AVERAGE | HWMON_P_AVERAGE_INTERVAL |
> +				  HWMON_P_LABEL,
> +				  HWMON_P_AVERAGE | HWMON_P_AVERAGE_INTERVAL |
> +				  HWMON_P_LABEL,
> +				  HWMON_P_AVERAGE | HWMON_P_AVERAGE_INTERVAL |
> +				  HWMON_P_LABEL,
> +				  HWMON_P_AVERAGE | HWMON_P_AVERAGE_INTERVAL |
> +				  HWMON_P_LABEL,
> +				  HWMON_P_AVERAGE | HWMON_P_AVERAGE_INTERVAL |
> +				  HWMON_P_LABEL,
> +				  HWMON_P_AVERAGE | HWMON_P_AVERAGE_INTERVAL |
> +				  HWMON_P_LABEL,
> +				  HWMON_P_AVERAGE | HWMON_P_AVERAGE_INTERVAL |
> +				  HWMON_P_LABEL,
> +				  HWMON_P_AVERAGE | HWMON_P_AVERAGE_INTERVAL |
> +				  HWMON_P_LABEL),
> +	NULL
> +};
> +
> +static const struct hwmon_chip_info lochnagar_chip_info = {
> +	.ops = &lochnagar_ops,
> +	.info = lochnagar_info,
> +};
> +
> +static const struct of_device_id lochnagar_of_match[] = {
> +	{ .compatible = "cirrus,lochnagar2-hwmon" },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, lochnagar_of_match);
> +
> +static int lochnagar_hwmon_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct device *hwmon_dev;
> +	struct lochnagar_hwmon *priv;
> +	int i;
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	mutex_init(&priv->sensor_lock);
> +
> +	priv->regmap = dev_get_regmap(dev->parent, NULL);
> +	if (!priv->regmap) {
> +		dev_err(dev, "No register map found\n");
> +		return -EINVAL;
> +	}
> +
> +	for (i = 0; i < ARRAY_SIZE(priv->power_nsamples); i++)
> +		priv->power_nsamples[i] = 96;
> +
> +	hwmon_dev = devm_hwmon_device_register_with_info(dev, "Lochnagar", priv,
> +							 &lochnagar_chip_info,
> +							 NULL);
> +
> +	return PTR_ERR_OR_ZERO(hwmon_dev);
> +}
> +
> +static struct platform_driver lochnagar_hwmon_driver = {
> +	.driver = {
> +		.name = "lochnagar-hwmon",
> +		.of_match_table = lochnagar_of_match,
> +	},
> +	.probe = lochnagar_hwmon_probe,
> +};
> +module_platform_driver(lochnagar_hwmon_driver);
> +
> +MODULE_AUTHOR("Lucas Tanure <tanureal@opensource.cirrus.com>");
> +MODULE_DESCRIPTION("Lochnagar hardware monitoring features");
> +MODULE_LICENSE("GPL");