drivers/hwmon/ina2xx.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Driver for Texas Instruments INA219, INA226 power monitor chips
  *
  * INA219:
  * Zero Drift Bi-Directional Current/Power Monitor with I2C Interface
  * Datasheet: http://www.ti.com/product/ina219
  *
  * INA220:
  * Bi-Directional Current/Power Monitor with I2C Interface
  * Datasheet: http://www.ti.com/product/ina220
  *
  * INA226:
  * Bi-Directional Current/Power Monitor with I2C Interface
  * Datasheet: http://www.ti.com/product/ina226
  *
  * INA230:
  * Bi-directional Current/Power Monitor with I2C Interface
  * Datasheet: http://www.ti.com/product/ina230
  *
  * Copyright (C) 2012 Lothar Felten <lothar.felten@gmail.com>
  * Thanks to Jan Volkering
  */

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/err.h>
 #include <linux/slab.h>
 #include <linux/i2c.h>
 #include <linux/hwmon.h>
 #include <linux/hwmon-sysfs.h>
 #include <linux/jiffies.h>
 #include <linux/of_device.h>
 #include <linux/of.h>
 #include <linux/delay.h>
 #include <linux/util_macros.h>
 #include <linux/regmap.h>

 #include <linux/platform_data/ina2xx.h>

 /* common register definitions */
 #define INA2XX_CONFIG			0x00
 #define INA2XX_SHUNT_VOLTAGE		0x01 /* readonly */
 #define INA2XX_BUS_VOLTAGE		0x02 /* readonly */
 #define INA2XX_POWER			0x03 /* readonly */
 #define INA2XX_CURRENT			0x04 /* readonly */
 #define INA2XX_CALIBRATION		0x05

 /* INA226 register definitions */
 #define INA226_MASK_ENABLE		0x06
 #define INA226_ALERT_LIMIT		0x07
 #define INA226_DIE_ID			0xFF

 /* register count */
 #define INA219_REGISTERS		6
 #define INA226_REGISTERS		8

 #define INA2XX_MAX_REGISTERS		8

 /* settings - depend on use case */
 #define INA219_CONFIG_DEFAULT		0x399F	/* PGA=8 */
 #define INA226_CONFIG_DEFAULT		0x4527	/* averages=16 */

 /* worst case is 68.10 ms (~14.6Hz, ina219) */
 #define INA2XX_CONVERSION_RATE		15
 #define INA2XX_MAX_DELAY		69 /* worst case delay in ms */

 #define INA2XX_RSHUNT_DEFAULT		10000

 /* bit mask for reading the averaging setting in the configuration register */
 #define INA226_AVG_RD_MASK		0x0E00

 #define INA226_READ_AVG(reg)		(((reg) & INA226_AVG_RD_MASK) >> 9)
 #define INA226_SHIFT_AVG(val)		((val) << 9)

 /* common attrs, ina226 attrs and NULL */
 #define INA2XX_MAX_ATTRIBUTE_GROUPS	3

 /*
  * Both bus voltage and shunt voltage conversion times for ina226 are set
  * to 0b0100 on POR, which translates to 2200 microseconds in total.
  */
 #define INA226_TOTAL_CONV_TIME_DEFAULT	2200

 static struct regmap_config ina2xx_regmap_config = {
 	.reg_bits = 8,
 	.val_bits = 16,
 };

 enum ina2xx_ids { ina219, ina226 };

 struct ina2xx_config {
 	u16 config_default;
 	int calibration_value;
 	int registers;
 	int shunt_div;
 	int bus_voltage_shift;
 	int bus_voltage_lsb;	/* uV */
 	int power_lsb_factor;
 };

 struct ina2xx_data {
 	const struct ina2xx_config *config;

 	long rshunt;
 	long current_lsb_uA;
 	long power_lsb_uW;
 	struct mutex config_lock;
 	struct regmap *regmap;

 	const struct attribute_group *groups[INA2XX_MAX_ATTRIBUTE_GROUPS];
 };

 static const struct ina2xx_config ina2xx_config[] = {
 	[ina219] = {
 		.config_default = INA219_CONFIG_DEFAULT,
 		.calibration_value = 4096,
 		.registers = INA219_REGISTERS,
 		.shunt_div = 100,
 		.bus_voltage_shift = 3,
 		.bus_voltage_lsb = 4000,
 		.power_lsb_factor = 20,
 	},
 	[ina226] = {
 		.config_default = INA226_CONFIG_DEFAULT,
 		.calibration_value = 2048,
 		.registers = INA226_REGISTERS,
 		.shunt_div = 400,
 		.bus_voltage_shift = 0,
 		.bus_voltage_lsb = 1250,
 		.power_lsb_factor = 25,
 	},
 };

 /*
  * Available averaging rates for ina226. The indices correspond with
  * the bit values expected by the chip (according to the ina226 datasheet,
  * table 3 AVG bit settings, found at
  * http://www.ti.com/lit/ds/symlink/ina226.pdf.
  */
 static const int ina226_avg_tab[] = { 1, 4, 16, 64, 128, 256, 512, 1024 };

 static int ina226_reg_to_interval(u16 config)
 {
 	int avg = ina226_avg_tab[INA226_READ_AVG(config)];

 	/*
 	 * Multiply the total conversion time by the number of averages.
 	 * Return the result in milliseconds.
 	 */
 	return DIV_ROUND_CLOSEST(avg * INA226_TOTAL_CONV_TIME_DEFAULT, 1000);
 }

 /*
  * Return the new, shifted AVG field value of CONFIG register,
  * to use with regmap_update_bits
  */
 static u16 ina226_interval_to_reg(int interval)
 {
 	int avg, avg_bits;

 	avg = DIV_ROUND_CLOSEST(interval * 1000,
 				INA226_TOTAL_CONV_TIME_DEFAULT);
 	avg_bits = find_closest(avg, ina226_avg_tab,
 				ARRAY_SIZE(ina226_avg_tab));

 	return INA226_SHIFT_AVG(avg_bits);
 }

 /*
  * Calibration register is set to the best value, which eliminates
  * truncation errors on calculating current register in hardware.
  * According to datasheet (eq. 3) the best values are 2048 for
  * ina226 and 4096 for ina219. They are hardcoded as calibration_value.
  */
 static int ina2xx_calibrate(struct ina2xx_data *data)
 {
 	return regmap_write(data->regmap, INA2XX_CALIBRATION,
 			    data->config->calibration_value);
 }

 /*
  * Initialize the configuration and calibration registers.
  */
 static int ina2xx_init(struct ina2xx_data *data)
 {
 	int ret = regmap_write(data->regmap, INA2XX_CONFIG,
 			       data->config->config_default);
 	if (ret < 0)
 		return ret;

 	return ina2xx_calibrate(data);
 }

 static int ina2xx_read_reg(struct device *dev, int reg, unsigned int *regval)
 {
 	struct ina2xx_data *data = dev_get_drvdata(dev);
 	int ret, retry;

 	dev_dbg(dev, "Starting register %d read\n", reg);

 	for (retry = 5; retry; retry--) {

 		ret = regmap_read(data->regmap, reg, regval);
 		if (ret < 0)
 			return ret;

 		dev_dbg(dev, "read %d, val = 0x%04x\n", reg, *regval);

 		/*
 		 * If the current value in the calibration register is 0, the
 		 * power and current registers will also remain at 0. In case
 		 * the chip has been reset let's check the calibration
 		 * register and reinitialize if needed.
 		 * We do that extra read of the calibration register if there
 		 * is some hint of a chip reset.
 		 */
 		if (*regval == 0) {
 			unsigned int cal;

 			ret = regmap_read(data->regmap, INA2XX_CALIBRATION,
 					  &cal);
 			if (ret < 0)
 				return ret;

 			if (cal == 0) {
 				dev_warn(dev, "chip not calibrated, reinitializing\n");

 				ret = ina2xx_init(data);
 				if (ret < 0)
 					return ret;
 				/*
 				 * Let's make sure the power and current
 				 * registers have been updated before trying
 				 * again.
 				 */
 				msleep(INA2XX_MAX_DELAY);
 				continue;
 			}
 		}
 		return 0;
 	}

 	/*
 	 * If we're here then although all write operations succeeded, the
 	 * chip still returns 0 in the calibration register. Nothing more we
 	 * can do here.
 	 */
 	dev_err(dev, "unable to reinitialize the chip\n");
 	return -ENODEV;
 }

 static int ina2xx_get_value(struct ina2xx_data *data, u8 reg,
 			    unsigned int regval)
 {
 	int val;

 	switch (reg) {
 	case INA2XX_SHUNT_VOLTAGE:
 		/* signed register */
 		val = DIV_ROUND_CLOSEST((s16)regval, data->config->shunt_div);
 		break;
 	case INA2XX_BUS_VOLTAGE:
 		val = (regval >> data->config->bus_voltage_shift)
 		  * data->config->bus_voltage_lsb;
 		val = DIV_ROUND_CLOSEST(val, 1000);
 		break;
 	case INA2XX_POWER:
 		val = regval * data->power_lsb_uW;
 		break;
 	case INA2XX_CURRENT:
 		/* signed register, result in mA */
 		val = (s16)regval * data->current_lsb_uA;
 		val = DIV_ROUND_CLOSEST(val, 1000);
 		break;
 	case INA2XX_CALIBRATION:
 		val = regval;
 		break;
 	default:
 		/* programmer goofed */
 		WARN_ON_ONCE(1);
 		val = 0;
 		break;
 	}

 	return val;
 }

 static ssize_t ina2xx_value_show(struct device *dev,
 				 struct device_attribute *da, char *buf)
 {
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 	struct ina2xx_data *data = dev_get_drvdata(dev);
 	unsigned int regval;

 	int err = ina2xx_read_reg(dev, attr->index, &regval);

 	if (err < 0)
 		return err;

 	return snprintf(buf, PAGE_SIZE, "%d\n",
 			ina2xx_get_value(data, attr->index, regval));
 }

 /*
  * In order to keep calibration register value fixed, the product
  * of current_lsb and shunt_resistor should also be fixed and equal
  * to shunt_voltage_lsb = 1 / shunt_div multiplied by 10^9 in order
  * to keep the scale.
  */
 static int ina2xx_set_shunt(struct ina2xx_data *data, long val)
 {
 	unsigned int dividend = DIV_ROUND_CLOSEST(1000000000,
 						  data->config->shunt_div);
 	if (val <= 0 || val > dividend)
 		return -EINVAL;

 	mutex_lock(&data->config_lock);
 	data->rshunt = val;
 	data->current_lsb_uA = DIV_ROUND_CLOSEST(dividend, val);
 	data->power_lsb_uW = data->config->power_lsb_factor *
 			     data->current_lsb_uA;
 	mutex_unlock(&data->config_lock);

 	return 0;
 }

 static ssize_t ina2xx_shunt_show(struct device *dev,
 				 struct device_attribute *da, char *buf)
 {
 	struct ina2xx_data *data = dev_get_drvdata(dev);

 	return snprintf(buf, PAGE_SIZE, "%li\n", data->rshunt);
 }

 static ssize_t ina2xx_shunt_store(struct device *dev,
 				  struct device_attribute *da,
 				  const char *buf, size_t count)
 {
 	unsigned long val;
 	int status;
 	struct ina2xx_data *data = dev_get_drvdata(dev);

 	status = kstrtoul(buf, 10, &val);
 	if (status < 0)
 		return status;

 	status = ina2xx_set_shunt(data, val);
 	if (status < 0)
 		return status;
 	return count;
 }

 static ssize_t ina226_interval_store(struct device *dev,
 				     struct device_attribute *da,
 				     const char *buf, size_t count)
 {
 	struct ina2xx_data *data = dev_get_drvdata(dev);
 	unsigned long val;
 	int status;

 	status = kstrtoul(buf, 10, &val);
 	if (status < 0)
 		return status;

 	if (val > INT_MAX || val == 0)
 		return -EINVAL;

 	status = regmap_update_bits(data->regmap, INA2XX_CONFIG,
 				    INA226_AVG_RD_MASK,
 				    ina226_interval_to_reg(val));
 	if (status < 0)
 		return status;

 	return count;
 }

 static ssize_t ina226_interval_show(struct device *dev,
 				    struct device_attribute *da, char *buf)
 {
 	struct ina2xx_data *data = dev_get_drvdata(dev);
 	int status;
 	unsigned int regval;

 	status = regmap_read(data->regmap, INA2XX_CONFIG, &regval);
 	if (status)
 		return status;

 	return snprintf(buf, PAGE_SIZE, "%d\n", ina226_reg_to_interval(regval));
 }

 /* shunt voltage */
 static SENSOR_DEVICE_ATTR_RO(in0_input, ina2xx_value, INA2XX_SHUNT_VOLTAGE);

 /* bus voltage */
 static SENSOR_DEVICE_ATTR_RO(in1_input, ina2xx_value, INA2XX_BUS_VOLTAGE);

 /* calculated current */
 static SENSOR_DEVICE_ATTR_RO(curr1_input, ina2xx_value, INA2XX_CURRENT);

 /* calculated power */
 static SENSOR_DEVICE_ATTR_RO(power1_input, ina2xx_value, INA2XX_POWER);

 /* shunt resistance */
 static SENSOR_DEVICE_ATTR_RW(shunt_resistor, ina2xx_shunt, INA2XX_CALIBRATION);

 /* update interval (ina226 only) */
 static SENSOR_DEVICE_ATTR_RW(update_interval, ina226_interval, 0);

 /* pointers to created device attributes */
 static struct attribute *ina2xx_attrs[] = {
 	&sensor_dev_attr_in0_input.dev_attr.attr,
 	&sensor_dev_attr_in1_input.dev_attr.attr,
 	&sensor_dev_attr_curr1_input.dev_attr.attr,
 	&sensor_dev_attr_power1_input.dev_attr.attr,
 	&sensor_dev_attr_shunt_resistor.dev_attr.attr,
 	NULL,
 };

 static const struct attribute_group ina2xx_group = {
 	.attrs = ina2xx_attrs,
 };

 static struct attribute *ina226_attrs[] = {
 	&sensor_dev_attr_update_interval.dev_attr.attr,
 	NULL,
 };

 static const struct attribute_group ina226_group = {
 	.attrs = ina226_attrs,
 };

 static int ina2xx_probe(struct i2c_client *client,
 			const struct i2c_device_id *id)
 {
 	struct device *dev = &client->dev;
 	struct ina2xx_data *data;
 	struct device *hwmon_dev;
 	u32 val;
 	int ret, group = 0;
 	enum ina2xx_ids chip;

 	if (client->dev.of_node)
 		chip = (enum ina2xx_ids)of_device_get_match_data(&client->dev);
 	else
 		chip = id->driver_data;

 	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;

 	/* set the device type */
 	data->config = &ina2xx_config[chip];
 	mutex_init(&data->config_lock);

 	if (of_property_read_u32(dev->of_node, "shunt-resistor", &val) < 0) {
 		struct ina2xx_platform_data *pdata = dev_get_platdata(dev);

 		if (pdata)
 			val = pdata->shunt_uohms;
 		else
 			val = INA2XX_RSHUNT_DEFAULT;
 	}

 	ina2xx_set_shunt(data, val);

 	ina2xx_regmap_config.max_register = data->config->registers;

 	data->regmap = devm_regmap_init_i2c(client, &ina2xx_regmap_config);
 	if (IS_ERR(data->regmap)) {
 		dev_err(dev, "failed to allocate register map\n");
 		return PTR_ERR(data->regmap);
 	}

 	ret = ina2xx_init(data);
 	if (ret < 0) {
 		dev_err(dev, "error configuring the device: %d\n", ret);
 		return -ENODEV;
 	}

 	data->groups[group++] = &ina2xx_group;
 	if (chip == ina226)
 		data->groups[group++] = &ina226_group;

 	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
 							   data, data->groups);
 	if (IS_ERR(hwmon_dev))
 		return PTR_ERR(hwmon_dev);

 	dev_info(dev, "power monitor %s (Rshunt = %li uOhm)\n",
 		 client->name, data->rshunt);

 	return 0;
 }

 static const struct i2c_device_id ina2xx_id[] = {
 	{ "ina219", ina219 },
 	{ "ina220", ina219 },
 	{ "ina226", ina226 },
 	{ "ina230", ina226 },
 	{ "ina231", ina226 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, ina2xx_id);

 static const struct of_device_id __maybe_unused ina2xx_of_match[] = {
 	{
 		.compatible = "ti,ina219",
 		.data = (void *)ina219
 	},
 	{
 		.compatible = "ti,ina220",
 		.data = (void *)ina219
 	},
 	{
 		.compatible = "ti,ina226",
 		.data = (void *)ina226
 	},
 	{
 		.compatible = "ti,ina230",
 		.data = (void *)ina226
 	},
 	{
 		.compatible = "ti,ina231",
 		.data = (void *)ina226
 	},
 	{ },
 };
 MODULE_DEVICE_TABLE(of, ina2xx_of_match);

 static struct i2c_driver ina2xx_driver = {
 	.driver = {
 		.name	= "ina2xx",
 		.of_match_table = of_match_ptr(ina2xx_of_match),
 	},
 	.probe		= ina2xx_probe,
 	.id_table	= ina2xx_id,
 };

 module_i2c_driver(ina2xx_driver);

 MODULE_AUTHOR("Lothar Felten <l-felten@ti.com>");
 MODULE_DESCRIPTION("ina2xx driver");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Driver for Texas Instruments INA219, INA226 power monitor chips
	*
	* INA219:
	* Zero Drift Bi-Directional Current/Power Monitor with I2C Interface
	* Datasheet: http://www.ti.com/product/ina219
	*
	* INA220:
	* Bi-Directional Current/Power Monitor with I2C Interface
	* Datasheet: http://www.ti.com/product/ina220
	*
	* INA226:
	* Bi-Directional Current/Power Monitor with I2C Interface
	* Datasheet: http://www.ti.com/product/ina226
	*
	* INA230:
	* Bi-directional Current/Power Monitor with I2C Interface
	* Datasheet: http://www.ti.com/product/ina230
	*
	* Copyright (C) 2012 Lothar Felten <lothar.felten@gmail.com>
	* Thanks to Jan Volkering
	*/

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/err.h>
	#include <linux/slab.h>
	#include <linux/i2c.h>
	#include <linux/hwmon.h>
	#include <linux/hwmon-sysfs.h>
	#include <linux/jiffies.h>
	#include <linux/of_device.h>
	#include <linux/of.h>
	#include <linux/delay.h>
	#include <linux/util_macros.h>
	#include <linux/regmap.h>

	#include <linux/platform_data/ina2xx.h>

	/* common register definitions */
	#define INA2XX_CONFIG 0x00
	#define INA2XX_SHUNT_VOLTAGE 0x01 /* readonly */
	#define INA2XX_BUS_VOLTAGE 0x02 /* readonly */
	#define INA2XX_POWER 0x03 /* readonly */
	#define INA2XX_CURRENT 0x04 /* readonly */
	#define INA2XX_CALIBRATION 0x05

	/* INA226 register definitions */
	#define INA226_MASK_ENABLE 0x06
	#define INA226_ALERT_LIMIT 0x07
	#define INA226_DIE_ID 0xFF

	/* register count */
	#define INA219_REGISTERS 6
	#define INA226_REGISTERS 8

	#define INA2XX_MAX_REGISTERS 8

	/* settings - depend on use case */
	#define INA219_CONFIG_DEFAULT 0x399F /* PGA=8 */
	#define INA226_CONFIG_DEFAULT 0x4527 /* averages=16 */

	/* worst case is 68.10 ms (~14.6Hz, ina219) */
	#define INA2XX_CONVERSION_RATE 15
	#define INA2XX_MAX_DELAY 69 /* worst case delay in ms */

	#define INA2XX_RSHUNT_DEFAULT 10000

	/* bit mask for reading the averaging setting in the configuration register */
	#define INA226_AVG_RD_MASK 0x0E00

	#define INA226_READ_AVG(reg) (((reg) & INA226_AVG_RD_MASK) >> 9)
	#define INA226_SHIFT_AVG(val) ((val) << 9)

	/* common attrs, ina226 attrs and NULL */
	#define INA2XX_MAX_ATTRIBUTE_GROUPS 3

	/*
	* Both bus voltage and shunt voltage conversion times for ina226 are set
	* to 0b0100 on POR, which translates to 2200 microseconds in total.
	*/
	#define INA226_TOTAL_CONV_TIME_DEFAULT 2200

	static struct regmap_config ina2xx_regmap_config = {
	.reg_bits = 8,
	.val_bits = 16,
	};

	enum ina2xx_ids { ina219, ina226 };

	struct ina2xx_config {
	u16 config_default;
	int calibration_value;
	int registers;
	int shunt_div;
	int bus_voltage_shift;
	int bus_voltage_lsb; /* uV */
	int power_lsb_factor;
	};

	struct ina2xx_data {
	const struct ina2xx_config *config;

	long rshunt;
	long current_lsb_uA;
	long power_lsb_uW;
	struct mutex config_lock;
	struct regmap *regmap;

	const struct attribute_group *groups[INA2XX_MAX_ATTRIBUTE_GROUPS];
	};

	static const struct ina2xx_config ina2xx_config[] = {
	[ina219] = {
	.config_default = INA219_CONFIG_DEFAULT,
	.calibration_value = 4096,
	.registers = INA219_REGISTERS,
	.shunt_div = 100,
	.bus_voltage_shift = 3,
	.bus_voltage_lsb = 4000,
	.power_lsb_factor = 20,
	},
	[ina226] = {
	.config_default = INA226_CONFIG_DEFAULT,
	.calibration_value = 2048,
	.registers = INA226_REGISTERS,
	.shunt_div = 400,
	.bus_voltage_shift = 0,
	.bus_voltage_lsb = 1250,
	.power_lsb_factor = 25,
	},
	};

	/*
	* Available averaging rates for ina226. The indices correspond with
	* the bit values expected by the chip (according to the ina226 datasheet,
	* table 3 AVG bit settings, found at
	* http://www.ti.com/lit/ds/symlink/ina226.pdf.
	*/
	static const int ina226_avg_tab[] = { 1, 4, 16, 64, 128, 256, 512, 1024 };

	static int ina226_reg_to_interval(u16 config)
	{
	int avg = ina226_avg_tab[INA226_READ_AVG(config)];

	/*
	* Multiply the total conversion time by the number of averages.
	* Return the result in milliseconds.
	*/
	return DIV_ROUND_CLOSEST(avg * INA226_TOTAL_CONV_TIME_DEFAULT, 1000);
	}

	/*
	* Return the new, shifted AVG field value of CONFIG register,
	* to use with regmap_update_bits
	*/
	static u16 ina226_interval_to_reg(int interval)
	{
	int avg, avg_bits;

	avg = DIV_ROUND_CLOSEST(interval * 1000,
	INA226_TOTAL_CONV_TIME_DEFAULT);
	avg_bits = find_closest(avg, ina226_avg_tab,
	ARRAY_SIZE(ina226_avg_tab));

	return INA226_SHIFT_AVG(avg_bits);
	}

	/*
	* Calibration register is set to the best value, which eliminates
	* truncation errors on calculating current register in hardware.
	* According to datasheet (eq. 3) the best values are 2048 for
	* ina226 and 4096 for ina219. They are hardcoded as calibration_value.
	*/
	static int ina2xx_calibrate(struct ina2xx_data *data)
	{
	return regmap_write(data->regmap, INA2XX_CALIBRATION,
	data->config->calibration_value);
	}

	/*
	* Initialize the configuration and calibration registers.
	*/
	static int ina2xx_init(struct ina2xx_data *data)
	{
	int ret = regmap_write(data->regmap, INA2XX_CONFIG,
	data->config->config_default);
	if (ret < 0)
	return ret;

	return ina2xx_calibrate(data);
	}

	static int ina2xx_read_reg(struct device dev, int reg, unsigned int regval)
	{
	struct ina2xx_data *data = dev_get_drvdata(dev);
	int ret, retry;

	dev_dbg(dev, "Starting register %d read\n", reg);

	for (retry = 5; retry; retry--) {

	ret = regmap_read(data->regmap, reg, regval);
	if (ret < 0)
	return ret;

	dev_dbg(dev, "read %d, val = 0x%04x\n", reg, *regval);

	/*
	* If the current value in the calibration register is 0, the
	* power and current registers will also remain at 0. In case
	* the chip has been reset let's check the calibration
	* register and reinitialize if needed.
	* We do that extra read of the calibration register if there
	* is some hint of a chip reset.
	*/
	if (*regval == 0) {
	unsigned int cal;

	ret = regmap_read(data->regmap, INA2XX_CALIBRATION,
	&cal);
	if (ret < 0)
	return ret;

	if (cal == 0) {
	dev_warn(dev, "chip not calibrated, reinitializing\n");

	ret = ina2xx_init(data);
	if (ret < 0)
	return ret;
	/*
	* Let's make sure the power and current
	* registers have been updated before trying
	* again.
	*/
	msleep(INA2XX_MAX_DELAY);
	continue;
	}
	}
	return 0;
	}

	/*
	* If we're here then although all write operations succeeded, the
	* chip still returns 0 in the calibration register. Nothing more we
	* can do here.
	*/
	dev_err(dev, "unable to reinitialize the chip\n");
	return -ENODEV;
	}

	static int ina2xx_get_value(struct ina2xx_data *data, u8 reg,
	unsigned int regval)
	{
	int val;

	switch (reg) {
	case INA2XX_SHUNT_VOLTAGE:
	/* signed register */
	val = DIV_ROUND_CLOSEST((s16)regval, data->config->shunt_div);
	break;
	case INA2XX_BUS_VOLTAGE:
	val = (regval >> data->config->bus_voltage_shift)
	* data->config->bus_voltage_lsb;
	val = DIV_ROUND_CLOSEST(val, 1000);
	break;
	case INA2XX_POWER:
	val = regval * data->power_lsb_uW;
	break;
	case INA2XX_CURRENT:
	/* signed register, result in mA */
	val = (s16)regval * data->current_lsb_uA;
	val = DIV_ROUND_CLOSEST(val, 1000);
	break;
	case INA2XX_CALIBRATION:
	val = regval;
	break;
	default:
	/* programmer goofed */
	WARN_ON_ONCE(1);
	val = 0;
	break;
	}

	return val;
	}

	static ssize_t ina2xx_value_show(struct device *dev,
	struct device_attribute da, char buf)
	{
	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
	struct ina2xx_data *data = dev_get_drvdata(dev);
	unsigned int regval;

	int err = ina2xx_read_reg(dev, attr->index, &regval);

	if (err < 0)
	return err;

	return snprintf(buf, PAGE_SIZE, "%d\n",
	ina2xx_get_value(data, attr->index, regval));
	}

	/*
	* In order to keep calibration register value fixed, the product
	* of current_lsb and shunt_resistor should also be fixed and equal
	* to shunt_voltage_lsb = 1 / shunt_div multiplied by 10^9 in order
	* to keep the scale.
	*/
	static int ina2xx_set_shunt(struct ina2xx_data *data, long val)
	{
	unsigned int dividend = DIV_ROUND_CLOSEST(1000000000,
	data->config->shunt_div);
	if (val <= 0 \|\| val > dividend)
	return -EINVAL;

	mutex_lock(&data->config_lock);
	data->rshunt = val;
	data->current_lsb_uA = DIV_ROUND_CLOSEST(dividend, val);
	data->power_lsb_uW = data->config->power_lsb_factor *
	data->current_lsb_uA;
	mutex_unlock(&data->config_lock);

	return 0;
	}

	static ssize_t ina2xx_shunt_show(struct device *dev,
	struct device_attribute da, char buf)
	{
	struct ina2xx_data *data = dev_get_drvdata(dev);

	return snprintf(buf, PAGE_SIZE, "%li\n", data->rshunt);
	}

	static ssize_t ina2xx_shunt_store(struct device *dev,
	struct device_attribute *da,
	const char *buf, size_t count)
	{
	unsigned long val;
	int status;
	struct ina2xx_data *data = dev_get_drvdata(dev);

	status = kstrtoul(buf, 10, &val);
	if (status < 0)
	return status;

	status = ina2xx_set_shunt(data, val);
	if (status < 0)
	return status;
	return count;
	}

	static ssize_t ina226_interval_store(struct device *dev,
	struct device_attribute *da,
	const char *buf, size_t count)
	{
	struct ina2xx_data *data = dev_get_drvdata(dev);
	unsigned long val;
	int status;

	status = kstrtoul(buf, 10, &val);
	if (status < 0)
	return status;

	if (val > INT_MAX \|\| val == 0)
	return -EINVAL;

	status = regmap_update_bits(data->regmap, INA2XX_CONFIG,
	INA226_AVG_RD_MASK,
	ina226_interval_to_reg(val));
	if (status < 0)
	return status;

	return count;
	}

	static ssize_t ina226_interval_show(struct device *dev,
	struct device_attribute da, char buf)
	{
	struct ina2xx_data *data = dev_get_drvdata(dev);
	int status;
	unsigned int regval;

	status = regmap_read(data->regmap, INA2XX_CONFIG, &regval);
	if (status)
	return status;

	return snprintf(buf, PAGE_SIZE, "%d\n", ina226_reg_to_interval(regval));
	}

	/* shunt voltage */
	static SENSOR_DEVICE_ATTR_RO(in0_input, ina2xx_value, INA2XX_SHUNT_VOLTAGE);

	/* bus voltage */
	static SENSOR_DEVICE_ATTR_RO(in1_input, ina2xx_value, INA2XX_BUS_VOLTAGE);

	/* calculated current */
	static SENSOR_DEVICE_ATTR_RO(curr1_input, ina2xx_value, INA2XX_CURRENT);

	/* calculated power */
	static SENSOR_DEVICE_ATTR_RO(power1_input, ina2xx_value, INA2XX_POWER);

	/* shunt resistance */
	static SENSOR_DEVICE_ATTR_RW(shunt_resistor, ina2xx_shunt, INA2XX_CALIBRATION);

	/* update interval (ina226 only) */
	static SENSOR_DEVICE_ATTR_RW(update_interval, ina226_interval, 0);

	/* pointers to created device attributes */
	static struct attribute *ina2xx_attrs[] = {
	&sensor_dev_attr_in0_input.dev_attr.attr,
	&sensor_dev_attr_in1_input.dev_attr.attr,
	&sensor_dev_attr_curr1_input.dev_attr.attr,
	&sensor_dev_attr_power1_input.dev_attr.attr,
	&sensor_dev_attr_shunt_resistor.dev_attr.attr,
	NULL,
	};

	static const struct attribute_group ina2xx_group = {
	.attrs = ina2xx_attrs,
	};

	static struct attribute *ina226_attrs[] = {
	&sensor_dev_attr_update_interval.dev_attr.attr,
	NULL,
	};

	static const struct attribute_group ina226_group = {
	.attrs = ina226_attrs,
	};

	static int ina2xx_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct device *dev = &client->dev;
	struct ina2xx_data *data;
	struct device *hwmon_dev;
	u32 val;
	int ret, group = 0;
	enum ina2xx_ids chip;

	if (client->dev.of_node)
	chip = (enum ina2xx_ids)of_device_get_match_data(&client->dev);
	else
	chip = id->driver_data;

	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
	if (!data)
	return -ENOMEM;

	/* set the device type */
	data->config = &ina2xx_config[chip];
	mutex_init(&data->config_lock);

	if (of_property_read_u32(dev->of_node, "shunt-resistor", &val) < 0) {
	struct ina2xx_platform_data *pdata = dev_get_platdata(dev);

	if (pdata)
	val = pdata->shunt_uohms;
	else
	val = INA2XX_RSHUNT_DEFAULT;
	}

	ina2xx_set_shunt(data, val);

	ina2xx_regmap_config.max_register = data->config->registers;

	data->regmap = devm_regmap_init_i2c(client, &ina2xx_regmap_config);
	if (IS_ERR(data->regmap)) {
	dev_err(dev, "failed to allocate register map\n");
	return PTR_ERR(data->regmap);
	}

	ret = ina2xx_init(data);
	if (ret < 0) {
	dev_err(dev, "error configuring the device: %d\n", ret);
	return -ENODEV;
	}

	data->groups[group++] = &ina2xx_group;
	if (chip == ina226)
	data->groups[group++] = &ina226_group;

	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
	data, data->groups);
	if (IS_ERR(hwmon_dev))
	return PTR_ERR(hwmon_dev);

	dev_info(dev, "power monitor %s (Rshunt = %li uOhm)\n",
	client->name, data->rshunt);

	return 0;
	}

	static const struct i2c_device_id ina2xx_id[] = {
	{ "ina219", ina219 },
	{ "ina220", ina219 },
	{ "ina226", ina226 },
	{ "ina230", ina226 },
	{ "ina231", ina226 },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, ina2xx_id);

	static const struct of_device_id __maybe_unused ina2xx_of_match[] = {
	{
	.compatible = "ti,ina219",
	.data = (void *)ina219
	},
	{
	.compatible = "ti,ina220",
	.data = (void *)ina219
	},
	{
	.compatible = "ti,ina226",
	.data = (void *)ina226
	},
	{
	.compatible = "ti,ina230",
	.data = (void *)ina226
	},
	{
	.compatible = "ti,ina231",
	.data = (void *)ina226
	},
	{ },
	};
	MODULE_DEVICE_TABLE(of, ina2xx_of_match);

	static struct i2c_driver ina2xx_driver = {
	.driver = {
	.name = "ina2xx",
	.of_match_table = of_match_ptr(ina2xx_of_match),
	},
	.probe = ina2xx_probe,
	.id_table = ina2xx_id,
	};

	module_i2c_driver(ina2xx_driver);

	MODULE_AUTHOR("Lothar Felten <l-felten@ti.com>");
	MODULE_DESCRIPTION("ina2xx driver");
	MODULE_LICENSE("GPL");