drivers/hwmon/lochnagar-hwmon.c - linux - Git at Google

 // 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");
	// 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");