drivers/hwmon/isl28022.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * isl28022.c - driver for Renesas ISL28022 power monitor chip monitoring
  *
  * Copyright (c) 2023 Carsten Spieß <mail@carsten-spiess.de>
  */

 #include <linux/debugfs.h>
 #include <linux/err.h>
 #include <linux/hwmon.h>
 #include <linux/i2c.h>
 #include <linux/module.h>
 #include <linux/regmap.h>

 /* ISL28022 registers */
 #define ISL28022_REG_CONFIG	0x00
 #define ISL28022_REG_SHUNT	0x01
 #define ISL28022_REG_BUS	0x02
 #define ISL28022_REG_POWER	0x03
 #define ISL28022_REG_CURRENT	0x04
 #define ISL28022_REG_CALIB	0x05
 #define ISL28022_REG_SHUNT_THR	0x06
 #define ISL28022_REG_BUS_THR	0x07
 #define ISL28022_REG_INT	0x08
 #define ISL28022_REG_AUX	0x09
 #define ISL28022_REG_MAX	ISL28022_REG_AUX

 /* ISL28022 config flags */
 /* mode flags */
 #define ISL28022_MODE_SHIFT	0
 #define ISL28022_MODE_MASK	0x0007

 #define ISL28022_MODE_PWR_DOWN	0x0
 #define ISL28022_MODE_TRG_S	0x1
 #define ISL28022_MODE_TRG_B	0x2
 #define ISL28022_MODE_TRG_SB	0x3
 #define ISL28022_MODE_ADC_OFF	0x4
 #define ISL28022_MODE_CONT_S	0x5
 #define ISL28022_MODE_CONT_B	0x6
 #define ISL28022_MODE_CONT_SB	0x7

 /* shunt ADC settings */
 #define ISL28022_SADC_SHIFT	3
 #define ISL28022_SADC_MASK	0x0078

 #define ISL28022_BADC_SHIFT	7
 #define ISL28022_BADC_MASK	0x0780

 #define ISL28022_ADC_12		0x0	/* 12 bit ADC */
 #define ISL28022_ADC_13		0x1	/* 13 bit ADC */
 #define ISL28022_ADC_14		0x2	/* 14 bit ADC */
 #define ISL28022_ADC_15		0x3	/* 15 bit ADC */
 #define ISL28022_ADC_15_1	0x8	/* 15 bit ADC, 1 sample */
 #define ISL28022_ADC_15_2	0x9	/* 15 bit ADC, 2 samples */
 #define ISL28022_ADC_15_4	0xA	/* 15 bit ADC, 4 samples */
 #define ISL28022_ADC_15_8	0xB	/* 15 bit ADC, 8 samples */
 #define ISL28022_ADC_15_16	0xC	/* 15 bit ADC, 16 samples */
 #define ISL28022_ADC_15_32	0xD	/* 15 bit ADC, 32 samples */
 #define ISL28022_ADC_15_64	0xE	/* 15 bit ADC, 64 samples */
 #define ISL28022_ADC_15_128	0xF	/* 15 bit ADC, 128 samples */

 /* shunt voltage range */
 #define ISL28022_PG_SHIFT	11
 #define ISL28022_PG_MASK	0x1800

 #define ISL28022_PG_40		0x0	/* +/-40 mV */
 #define ISL28022_PG_80		0x1	/* +/-80 mV */
 #define ISL28022_PG_160		0x2	/* +/-160 mV */
 #define ISL28022_PG_320		0x3	/* +/-3200 mV */

 /* bus voltage range */
 #define ISL28022_BRNG_SHIFT	13
 #define ISL28022_BRNG_MASK	0x6000

 #define ISL28022_BRNG_16	0x0	/* 16 V */
 #define ISL28022_BRNG_32	0x1	/* 32 V */
 #define ISL28022_BRNG_60	0x3	/* 60 V */

 /* reset */
 #define ISL28022_RESET		0x8000

 struct isl28022_data {
 	struct regmap		*regmap;
 	u32			shunt;
 	u32			gain;
 	u32			average;
 };

 static int isl28022_read_in(struct device *dev, u32 attr, int channel, long *val)
 {
 	struct isl28022_data *data = dev_get_drvdata(dev);
 	unsigned int regval;
 	int err;
 	u16 sign_bit;

 	switch (channel) {
 	case 0:
 		switch (attr) {
 		case hwmon_in_input:
 			err = regmap_read(data->regmap,
 					  ISL28022_REG_BUS, &regval);
 			if (err < 0)
 				return err;
 			/* driver supports only 60V mode (BRNG 11) */
 			*val = (long)(((u16)regval) & 0xFFFC);
 			break;
 		default:
 			return -EOPNOTSUPP;
 		}
 		break;
 	case 1:
 		switch (attr) {
 		case hwmon_in_input:
 			err = regmap_read(data->regmap,
 					  ISL28022_REG_SHUNT, &regval);
 			if (err < 0)
 				return err;
 			switch (data->gain) {
 			case 8:
 				sign_bit = (regval >> 15) & 0x01;
 				*val = (long)((((u16)regval) & 0x7FFF) -
 					(sign_bit * 32768)) / 100;
 				break;
 			case 4:
 				sign_bit = (regval >> 14) & 0x01;
 				*val = (long)((((u16)regval) & 0x3FFF) -
 					(sign_bit * 16384)) / 100;
 				break;
 			case 2:
 				sign_bit = (regval >> 13) & 0x01;
 				*val = (long)((((u16)regval) & 0x1FFF) -
 					(sign_bit * 8192)) / 100;
 				break;
 			case 1:
 				sign_bit = (regval >> 12) & 0x01;
 				*val = (long)((((u16)regval) & 0x0FFF) -
 					(sign_bit * 4096)) / 100;
 				break;
 			}
 			break;
 		default:
 			return -EOPNOTSUPP;
 		}
 		break;
 	default:
 		return -EOPNOTSUPP;
 	}

 	return 0;
 }

 static int isl28022_read_current(struct device *dev, u32 attr, long *val)
 {
 	struct isl28022_data *data = dev_get_drvdata(dev);
 	unsigned int regval;
 	int err;

 	switch (attr) {
 	case hwmon_curr_input:
 		err = regmap_read(data->regmap,
 				  ISL28022_REG_CURRENT, &regval);
 		if (err < 0)
 			return err;
 		*val = ((long)regval * 1250L * (long)data->gain) /
 			(long)data->shunt;
 		break;
 	default:
 		return -EOPNOTSUPP;
 	}

 	return 0;
 }

 static int isl28022_read_power(struct device *dev, u32 attr, long *val)
 {
 	struct isl28022_data *data = dev_get_drvdata(dev);
 	unsigned int regval;
 	int err;

 	switch (attr) {
 	case hwmon_power_input:
 		err = regmap_read(data->regmap,
 				  ISL28022_REG_POWER, &regval);
 		if (err < 0)
 			return err;
 		*val = ((51200000L * ((long)data->gain)) /
 			(long)data->shunt) * (long)regval;
 		break;
 	default:
 		return -EOPNOTSUPP;
 	}

 	return 0;
 }

 static int isl28022_read(struct device *dev, enum hwmon_sensor_types type,
 			 u32 attr, int channel, long *val)
 {
 	switch (type) {
 	case hwmon_in:
 		return isl28022_read_in(dev, attr, channel, val);
 	case hwmon_curr:
 		return isl28022_read_current(dev, attr, val);
 	case hwmon_power:
 		return isl28022_read_power(dev, attr, val);
 	default:
 		return -EOPNOTSUPP;
 	}
 	return 0;
 }

 static umode_t isl28022_is_visible(const void *data, enum hwmon_sensor_types type,
 				   u32 attr, int channel)
 {
 	switch (type) {
 	case hwmon_in:
 		switch (attr) {
 		case hwmon_in_input:
 			return 0444;
 		default:
 			break;
 		}
 		break;
 	case hwmon_curr:
 		switch (attr) {
 		case hwmon_curr_input:
 			return 0444;
 		default:
 			break;
 		}
 		break;
 	case hwmon_power:
 		switch (attr) {
 		case hwmon_power_input:
 			return 0444;
 		default:
 			break;
 		}
 		break;
 	default:
 		break;
 	}
 	return 0;
 }

 static const struct hwmon_channel_info *isl28022_info[] = {
 	HWMON_CHANNEL_INFO(in,
 			   HWMON_I_INPUT,	/* channel 0: bus voltage (mV) */
 			   HWMON_I_INPUT),	/* channel 1: shunt voltage (mV) */
 	HWMON_CHANNEL_INFO(curr,
 			   HWMON_C_INPUT),	/* channel 1: current (mA) */
 	HWMON_CHANNEL_INFO(power,
 			   HWMON_P_INPUT),	/* channel 1: power (µW) */
 	NULL
 };

 static const struct hwmon_ops isl28022_hwmon_ops = {
 	.is_visible = isl28022_is_visible,
 	.read = isl28022_read,
 };

 static const struct hwmon_chip_info isl28022_chip_info = {
 	.ops = &isl28022_hwmon_ops,
 	.info = isl28022_info,
 };

 static bool isl28022_is_writeable_reg(struct device *dev, unsigned int reg)
 {
 	switch (reg) {
 	case ISL28022_REG_CONFIG:
 	case ISL28022_REG_CALIB:
 	case ISL28022_REG_SHUNT_THR:
 	case ISL28022_REG_BUS_THR:
 	case ISL28022_REG_INT:
 	case ISL28022_REG_AUX:
 		return true;
 	}

 	return false;
 }

 static bool isl28022_is_volatile_reg(struct device *dev, unsigned int reg)
 {
 	switch (reg) {
 	case ISL28022_REG_CONFIG:
 	case ISL28022_REG_SHUNT:
 	case ISL28022_REG_BUS:
 	case ISL28022_REG_POWER:
 	case ISL28022_REG_CURRENT:
 	case ISL28022_REG_INT:
 	case ISL28022_REG_AUX:
 		return true;
 	}
 	return true;
 }

 static const struct regmap_config isl28022_regmap_config = {
 	.reg_bits = 8,
 	.val_bits = 16,
 	.max_register = ISL28022_REG_MAX,
 	.writeable_reg = isl28022_is_writeable_reg,
 	.volatile_reg = isl28022_is_volatile_reg,
 	.val_format_endian = REGMAP_ENDIAN_BIG,
 	.cache_type = REGCACHE_RBTREE,
 	.use_single_read = true,
 	.use_single_write = true,
 };

 static int shunt_voltage_show(struct seq_file *seqf, void *unused)
 {
 	struct isl28022_data *data = seqf->private;
 	unsigned int regval;
 	int err;

 	err = regmap_read(data->regmap,
 			  ISL28022_REG_SHUNT, &regval);
 	if (err)
 		return err;

 	/* print shunt voltage in micro volt  */
 	seq_printf(seqf, "%d\n", regval * 10);

 	return 0;
 }
 DEFINE_SHOW_ATTRIBUTE(shunt_voltage);

 static struct dentry *isl28022_debugfs_root;

 static void isl28022_debugfs_remove(void *res)
 {
 	debugfs_remove_recursive(res);
 }

 static void isl28022_debugfs_init(struct i2c_client *client, struct isl28022_data *data)
 {
 	char name[16];
 	struct dentry *debugfs;

 	scnprintf(name, sizeof(name), "%d-%04hx", client->adapter->nr, client->addr);

 	debugfs = debugfs_create_dir(name, isl28022_debugfs_root);
 	debugfs_create_file("shunt_voltage", 0444, debugfs, data, &shunt_voltage_fops);

 	devm_add_action_or_reset(&client->dev, isl28022_debugfs_remove, debugfs);
 }

 /*
  * read property values and make consistency checks.
  *
  * following values for shunt range and resistor are allowed:
  *   40 mV -> gain 1, shunt min.  800 micro ohms
  *   80 mV -> gain 2, shunt min. 1600 micro ohms
  *  160 mV -> gain 4, shunt min. 3200 micro ohms
  *  320 mV -> gain 8, shunt min. 6400 micro ohms
  */
 static int isl28022_read_properties(struct device *dev, struct isl28022_data *data)
 {
 	u32 val;
 	int err;

 	err = device_property_read_u32(dev, "shunt-resistor-micro-ohms", &val);
 	if (err == -EINVAL)
 		val = 10000;
 	else if (err < 0)
 		return err;
 	data->shunt = val;

 	err = device_property_read_u32(dev, "renesas,shunt-range-microvolt", &val);
 	if (err == -EINVAL)
 		val = 320000;
 	else if (err < 0)
 		return err;

 	switch (val) {
 	case 40000:
 		data->gain = 1;
 		if (data->shunt < 800)
 			goto shunt_invalid;
 		break;
 	case 80000:
 		data->gain = 2;
 		if (data->shunt < 1600)
 			goto shunt_invalid;
 		break;
 	case 160000:
 		data->gain = 4;
 		if (data->shunt < 3200)
 			goto shunt_invalid;
 		break;
 	case 320000:
 		data->gain = 8;
 		if (data->shunt < 6400)
 			goto shunt_invalid;
 		break;
 	default:
 		return dev_err_probe(dev, -EINVAL,
 				     "renesas,shunt-range-microvolt invalid value %d\n",
 				     val);
 	}

 	err = device_property_read_u32(dev, "renesas,average-samples", &val);
 	if (err == -EINVAL)
 		val = 1;
 	else if (err < 0)
 		return err;
 	if (val > 128 || hweight32(val) != 1)
 		return dev_err_probe(dev, -EINVAL,
 				     "renesas,average-samples invalid value %d\n",
 				     val);

 	data->average = val;

 	return 0;

 shunt_invalid:
 	return dev_err_probe(dev, -EINVAL,
 			     "renesas,shunt-resistor-microvolt invalid value %d\n",
 			     data->shunt);
 }

 /*
  * write configuration and calibration registers
  *
  * The driver supports only shunt and bus continuous ADC mode at 15bit resolution
  * with averaging from 1 to 128 samples (pow of 2) on both channels.
  * Shunt voltage gain 1,2,4 or 8 is allowed.
  * The bus voltage range is 60V fixed.
  */
 static int isl28022_config(struct isl28022_data *data)
 {
 	int err;
 	u16 config;
 	u16 calib;

 	config = (ISL28022_MODE_CONT_SB << ISL28022_MODE_SHIFT) |
 			(ISL28022_BRNG_60 << ISL28022_BRNG_SHIFT) |
 			(__ffs(data->gain) << ISL28022_PG_SHIFT) |
 			((ISL28022_ADC_15_1 + __ffs(data->average)) << ISL28022_SADC_SHIFT) |
 			((ISL28022_ADC_15_1 + __ffs(data->average)) << ISL28022_BADC_SHIFT);

 	calib = data->shunt ? 0x8000 / data->gain : 0;

 	err = regmap_write(data->regmap, ISL28022_REG_CONFIG, config);
 	if (err < 0)
 		return err;

 	return regmap_write(data->regmap, ISL28022_REG_CALIB, calib);
 }

 static int isl28022_probe(struct i2c_client *client)
 {
 	struct device *dev = &client->dev;
 	struct device *hwmon_dev;
 	struct isl28022_data *data;
 	int err;

 	if (!i2c_check_functionality(client->adapter,
 				     I2C_FUNC_SMBUS_BYTE_DATA |
 				     I2C_FUNC_SMBUS_WORD_DATA))
 		return -ENODEV;

 	data = devm_kzalloc(dev, sizeof(struct isl28022_data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;

 	err = isl28022_read_properties(dev, data);
 	if (err)
 		return err;

 	data->regmap = devm_regmap_init_i2c(client, &isl28022_regmap_config);
 	if (IS_ERR(data->regmap))
 		return PTR_ERR(data->regmap);

 	err = isl28022_config(data);
 	if (err)
 		return err;

 	isl28022_debugfs_init(client, data);

 	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
 							 data, &isl28022_chip_info, NULL);
 	if (IS_ERR(hwmon_dev))
 		return PTR_ERR(hwmon_dev);

 	return 0;
 }

 static const struct i2c_device_id isl28022_ids[] = {
 	{ "isl28022", 0},
 	{ /* LIST END */ }
 };
 MODULE_DEVICE_TABLE(i2c, isl28022_ids);

 static const struct of_device_id __maybe_unused isl28022_of_match[] = {
 	{ .compatible = "renesas,isl28022"},
 	{ /* LIST END */ }
 };
 MODULE_DEVICE_TABLE(of, isl28022_of_match);

 static struct i2c_driver isl28022_driver = {
 	.class		= I2C_CLASS_HWMON,
 	.driver = {
 		.name	= "isl28022",
 	},
 	.probe	= isl28022_probe,
 	.id_table	= isl28022_ids,
 };

 static int __init
 isl28022_init(void)
 {
 	int err;

 	isl28022_debugfs_root = debugfs_create_dir("isl28022", NULL);
 	err = i2c_add_driver(&isl28022_driver);
 	if (!err)
 		return 0;

 	debugfs_remove_recursive(isl28022_debugfs_root);
 	return err;
 }

 static void __exit
 isl28022_exit(void)
 {
 	i2c_del_driver(&isl28022_driver);
 	debugfs_remove_recursive(isl28022_debugfs_root);
 }

 module_init(isl28022_init);
 module_exit(isl28022_exit);

 MODULE_AUTHOR("Carsten Spieß <mail@carsten-spiess.de>");
 MODULE_DESCRIPTION("ISL28022 driver");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* isl28022.c - driver for Renesas ISL28022 power monitor chip monitoring
	*
	* Copyright (c) 2023 Carsten Spieß <mail@carsten-spiess.de>
	*/

	#include <linux/debugfs.h>
	#include <linux/err.h>
	#include <linux/hwmon.h>
	#include <linux/i2c.h>
	#include <linux/module.h>
	#include <linux/regmap.h>

	/* ISL28022 registers */
	#define ISL28022_REG_CONFIG 0x00
	#define ISL28022_REG_SHUNT 0x01
	#define ISL28022_REG_BUS 0x02
	#define ISL28022_REG_POWER 0x03
	#define ISL28022_REG_CURRENT 0x04
	#define ISL28022_REG_CALIB 0x05
	#define ISL28022_REG_SHUNT_THR 0x06
	#define ISL28022_REG_BUS_THR 0x07
	#define ISL28022_REG_INT 0x08
	#define ISL28022_REG_AUX 0x09
	#define ISL28022_REG_MAX ISL28022_REG_AUX

	/* ISL28022 config flags */
	/* mode flags */
	#define ISL28022_MODE_SHIFT 0
	#define ISL28022_MODE_MASK 0x0007

	#define ISL28022_MODE_PWR_DOWN 0x0
	#define ISL28022_MODE_TRG_S 0x1
	#define ISL28022_MODE_TRG_B 0x2
	#define ISL28022_MODE_TRG_SB 0x3
	#define ISL28022_MODE_ADC_OFF 0x4
	#define ISL28022_MODE_CONT_S 0x5
	#define ISL28022_MODE_CONT_B 0x6
	#define ISL28022_MODE_CONT_SB 0x7

	/* shunt ADC settings */
	#define ISL28022_SADC_SHIFT 3
	#define ISL28022_SADC_MASK 0x0078

	#define ISL28022_BADC_SHIFT 7
	#define ISL28022_BADC_MASK 0x0780

	#define ISL28022_ADC_12 0x0 /* 12 bit ADC */
	#define ISL28022_ADC_13 0x1 /* 13 bit ADC */
	#define ISL28022_ADC_14 0x2 /* 14 bit ADC */
	#define ISL28022_ADC_15 0x3 /* 15 bit ADC */
	#define ISL28022_ADC_15_1 0x8 /* 15 bit ADC, 1 sample */
	#define ISL28022_ADC_15_2 0x9 /* 15 bit ADC, 2 samples */
	#define ISL28022_ADC_15_4 0xA /* 15 bit ADC, 4 samples */
	#define ISL28022_ADC_15_8 0xB /* 15 bit ADC, 8 samples */
	#define ISL28022_ADC_15_16 0xC /* 15 bit ADC, 16 samples */
	#define ISL28022_ADC_15_32 0xD /* 15 bit ADC, 32 samples */
	#define ISL28022_ADC_15_64 0xE /* 15 bit ADC, 64 samples */
	#define ISL28022_ADC_15_128 0xF /* 15 bit ADC, 128 samples */

	/* shunt voltage range */
	#define ISL28022_PG_SHIFT 11
	#define ISL28022_PG_MASK 0x1800

	#define ISL28022_PG_40 0x0 /* +/-40 mV */
	#define ISL28022_PG_80 0x1 /* +/-80 mV */
	#define ISL28022_PG_160 0x2 /* +/-160 mV */
	#define ISL28022_PG_320 0x3 /* +/-3200 mV */

	/* bus voltage range */
	#define ISL28022_BRNG_SHIFT 13
	#define ISL28022_BRNG_MASK 0x6000

	#define ISL28022_BRNG_16 0x0 /* 16 V */
	#define ISL28022_BRNG_32 0x1 /* 32 V */
	#define ISL28022_BRNG_60 0x3 /* 60 V */

	/* reset */
	#define ISL28022_RESET 0x8000

	struct isl28022_data {
	struct regmap *regmap;
	u32 shunt;
	u32 gain;
	u32 average;
	};

	static int isl28022_read_in(struct device dev, u32 attr, int channel, long val)
	{
	struct isl28022_data *data = dev_get_drvdata(dev);
	unsigned int regval;
	int err;
	u16 sign_bit;

	switch (channel) {
	case 0:
	switch (attr) {
	case hwmon_in_input:
	err = regmap_read(data->regmap,
	ISL28022_REG_BUS, &regval);
	if (err < 0)
	return err;
	/* driver supports only 60V mode (BRNG 11) */
	*val = (long)(((u16)regval) & 0xFFFC);
	break;
	default:
	return -EOPNOTSUPP;
	}
	break;
	case 1:
	switch (attr) {
	case hwmon_in_input:
	err = regmap_read(data->regmap,
	ISL28022_REG_SHUNT, &regval);
	if (err < 0)
	return err;
	switch (data->gain) {
	case 8:
	sign_bit = (regval >> 15) & 0x01;
	*val = (long)((((u16)regval) & 0x7FFF) -
	(sign_bit * 32768)) / 100;
	break;
	case 4:
	sign_bit = (regval >> 14) & 0x01;
	*val = (long)((((u16)regval) & 0x3FFF) -
	(sign_bit * 16384)) / 100;
	break;
	case 2:
	sign_bit = (regval >> 13) & 0x01;
	*val = (long)((((u16)regval) & 0x1FFF) -
	(sign_bit * 8192)) / 100;
	break;
	case 1:
	sign_bit = (regval >> 12) & 0x01;
	*val = (long)((((u16)regval) & 0x0FFF) -
	(sign_bit * 4096)) / 100;
	break;
	}
	break;
	default:
	return -EOPNOTSUPP;
	}
	break;
	default:
	return -EOPNOTSUPP;
	}

	return 0;
	}

	static int isl28022_read_current(struct device dev, u32 attr, long val)
	{
	struct isl28022_data *data = dev_get_drvdata(dev);
	unsigned int regval;
	int err;

	switch (attr) {
	case hwmon_curr_input:
	err = regmap_read(data->regmap,
	ISL28022_REG_CURRENT, &regval);
	if (err < 0)
	return err;
	val = ((long)regval 1250L * (long)data->gain) /
	(long)data->shunt;
	break;
	default:
	return -EOPNOTSUPP;
	}

	return 0;
	}

	static int isl28022_read_power(struct device dev, u32 attr, long val)
	{
	struct isl28022_data *data = dev_get_drvdata(dev);
	unsigned int regval;
	int err;

	switch (attr) {
	case hwmon_power_input:
	err = regmap_read(data->regmap,
	ISL28022_REG_POWER, &regval);
	if (err < 0)
	return err;
	val = ((51200000L ((long)data->gain)) /
	(long)data->shunt) * (long)regval;
	break;
	default:
	return -EOPNOTSUPP;
	}

	return 0;
	}

	static int isl28022_read(struct device *dev, enum hwmon_sensor_types type,
	u32 attr, int channel, long *val)
	{
	switch (type) {
	case hwmon_in:
	return isl28022_read_in(dev, attr, channel, val);
	case hwmon_curr:
	return isl28022_read_current(dev, attr, val);
	case hwmon_power:
	return isl28022_read_power(dev, attr, val);
	default:
	return -EOPNOTSUPP;
	}
	return 0;
	}

	static umode_t isl28022_is_visible(const void *data, enum hwmon_sensor_types type,
	u32 attr, int channel)
	{
	switch (type) {
	case hwmon_in:
	switch (attr) {
	case hwmon_in_input:
	return 0444;
	default:
	break;
	}
	break;
	case hwmon_curr:
	switch (attr) {
	case hwmon_curr_input:
	return 0444;
	default:
	break;
	}
	break;
	case hwmon_power:
	switch (attr) {
	case hwmon_power_input:
	return 0444;
	default:
	break;
	}
	break;
	default:
	break;
	}
	return 0;
	}

	static const struct hwmon_channel_info *isl28022_info[] = {
	HWMON_CHANNEL_INFO(in,
	HWMON_I_INPUT, /* channel 0: bus voltage (mV) */
	HWMON_I_INPUT), /* channel 1: shunt voltage (mV) */
	HWMON_CHANNEL_INFO(curr,
	HWMON_C_INPUT), /* channel 1: current (mA) */
	HWMON_CHANNEL_INFO(power,
	HWMON_P_INPUT), /* channel 1: power (µW) */
	NULL
	};

	static const struct hwmon_ops isl28022_hwmon_ops = {
	.is_visible = isl28022_is_visible,
	.read = isl28022_read,
	};

	static const struct hwmon_chip_info isl28022_chip_info = {
	.ops = &isl28022_hwmon_ops,
	.info = isl28022_info,
	};

	static bool isl28022_is_writeable_reg(struct device *dev, unsigned int reg)
	{
	switch (reg) {
	case ISL28022_REG_CONFIG:
	case ISL28022_REG_CALIB:
	case ISL28022_REG_SHUNT_THR:
	case ISL28022_REG_BUS_THR:
	case ISL28022_REG_INT:
	case ISL28022_REG_AUX:
	return true;
	}

	return false;
	}

	static bool isl28022_is_volatile_reg(struct device *dev, unsigned int reg)
	{
	switch (reg) {
	case ISL28022_REG_CONFIG:
	case ISL28022_REG_SHUNT:
	case ISL28022_REG_BUS:
	case ISL28022_REG_POWER:
	case ISL28022_REG_CURRENT:
	case ISL28022_REG_INT:
	case ISL28022_REG_AUX:
	return true;
	}
	return true;
	}

	static const struct regmap_config isl28022_regmap_config = {
	.reg_bits = 8,
	.val_bits = 16,
	.max_register = ISL28022_REG_MAX,
	.writeable_reg = isl28022_is_writeable_reg,
	.volatile_reg = isl28022_is_volatile_reg,
	.val_format_endian = REGMAP_ENDIAN_BIG,
	.cache_type = REGCACHE_RBTREE,
	.use_single_read = true,
	.use_single_write = true,
	};

	static int shunt_voltage_show(struct seq_file seqf, void unused)
	{
	struct isl28022_data *data = seqf->private;
	unsigned int regval;
	int err;

	err = regmap_read(data->regmap,
	ISL28022_REG_SHUNT, &regval);
	if (err)
	return err;

	/* print shunt voltage in micro volt */
	seq_printf(seqf, "%d\n", regval * 10);

	return 0;
	}
	DEFINE_SHOW_ATTRIBUTE(shunt_voltage);

	static struct dentry *isl28022_debugfs_root;

	static void isl28022_debugfs_remove(void *res)
	{
	debugfs_remove_recursive(res);
	}

	static void isl28022_debugfs_init(struct i2c_client client, struct isl28022_data data)
	{
	char name[16];
	struct dentry *debugfs;

	scnprintf(name, sizeof(name), "%d-%04hx", client->adapter->nr, client->addr);

	debugfs = debugfs_create_dir(name, isl28022_debugfs_root);
	debugfs_create_file("shunt_voltage", 0444, debugfs, data, &shunt_voltage_fops);

	devm_add_action_or_reset(&client->dev, isl28022_debugfs_remove, debugfs);
	}

	/*
	* read property values and make consistency checks.
	*
	* following values for shunt range and resistor are allowed:
	* 40 mV -> gain 1, shunt min. 800 micro ohms
	* 80 mV -> gain 2, shunt min. 1600 micro ohms
	* 160 mV -> gain 4, shunt min. 3200 micro ohms
	* 320 mV -> gain 8, shunt min. 6400 micro ohms
	*/
	static int isl28022_read_properties(struct device dev, struct isl28022_data data)
	{
	u32 val;
	int err;

	err = device_property_read_u32(dev, "shunt-resistor-micro-ohms", &val);
	if (err == -EINVAL)
	val = 10000;
	else if (err < 0)
	return err;
	data->shunt = val;

	err = device_property_read_u32(dev, "renesas,shunt-range-microvolt", &val);
	if (err == -EINVAL)
	val = 320000;
	else if (err < 0)
	return err;

	switch (val) {
	case 40000:
	data->gain = 1;
	if (data->shunt < 800)
	goto shunt_invalid;
	break;
	case 80000:
	data->gain = 2;
	if (data->shunt < 1600)
	goto shunt_invalid;
	break;
	case 160000:
	data->gain = 4;
	if (data->shunt < 3200)
	goto shunt_invalid;
	break;
	case 320000:
	data->gain = 8;
	if (data->shunt < 6400)
	goto shunt_invalid;
	break;
	default:
	return dev_err_probe(dev, -EINVAL,
	"renesas,shunt-range-microvolt invalid value %d\n",
	val);
	}

	err = device_property_read_u32(dev, "renesas,average-samples", &val);
	if (err == -EINVAL)
	val = 1;
	else if (err < 0)
	return err;
	if (val > 128 \|\| hweight32(val) != 1)
	return dev_err_probe(dev, -EINVAL,
	"renesas,average-samples invalid value %d\n",
	val);

	data->average = val;

	return 0;

	shunt_invalid:
	return dev_err_probe(dev, -EINVAL,
	"renesas,shunt-resistor-microvolt invalid value %d\n",
	data->shunt);
	}

	/*
	* write configuration and calibration registers
	*
	* The driver supports only shunt and bus continuous ADC mode at 15bit resolution
	* with averaging from 1 to 128 samples (pow of 2) on both channels.
	* Shunt voltage gain 1,2,4 or 8 is allowed.
	* The bus voltage range is 60V fixed.
	*/
	static int isl28022_config(struct isl28022_data *data)
	{
	int err;
	u16 config;
	u16 calib;

	config = (ISL28022_MODE_CONT_SB << ISL28022_MODE_SHIFT) \|
	(ISL28022_BRNG_60 << ISL28022_BRNG_SHIFT) \|
	(__ffs(data->gain) << ISL28022_PG_SHIFT) \|
	((ISL28022_ADC_15_1 + __ffs(data->average)) << ISL28022_SADC_SHIFT) \|
	((ISL28022_ADC_15_1 + __ffs(data->average)) << ISL28022_BADC_SHIFT);

	calib = data->shunt ? 0x8000 / data->gain : 0;

	err = regmap_write(data->regmap, ISL28022_REG_CONFIG, config);
	if (err < 0)
	return err;

	return regmap_write(data->regmap, ISL28022_REG_CALIB, calib);
	}

	static int isl28022_probe(struct i2c_client *client)
	{
	struct device *dev = &client->dev;
	struct device *hwmon_dev;
	struct isl28022_data *data;
	int err;

	if (!i2c_check_functionality(client->adapter,
	I2C_FUNC_SMBUS_BYTE_DATA \|
	I2C_FUNC_SMBUS_WORD_DATA))
	return -ENODEV;

	data = devm_kzalloc(dev, sizeof(struct isl28022_data), GFP_KERNEL);
	if (!data)
	return -ENOMEM;

	err = isl28022_read_properties(dev, data);
	if (err)
	return err;

	data->regmap = devm_regmap_init_i2c(client, &isl28022_regmap_config);
	if (IS_ERR(data->regmap))
	return PTR_ERR(data->regmap);

	err = isl28022_config(data);
	if (err)
	return err;

	isl28022_debugfs_init(client, data);

	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
	data, &isl28022_chip_info, NULL);
	if (IS_ERR(hwmon_dev))
	return PTR_ERR(hwmon_dev);

	return 0;
	}

	static const struct i2c_device_id isl28022_ids[] = {
	{ "isl28022", 0},
	{ /* LIST END */ }
	};
	MODULE_DEVICE_TABLE(i2c, isl28022_ids);

	static const struct of_device_id __maybe_unused isl28022_of_match[] = {
	{ .compatible = "renesas,isl28022"},
	{ /* LIST END */ }
	};
	MODULE_DEVICE_TABLE(of, isl28022_of_match);

	static struct i2c_driver isl28022_driver = {
	.class = I2C_CLASS_HWMON,
	.driver = {
	.name = "isl28022",
	},
	.probe = isl28022_probe,
	.id_table = isl28022_ids,
	};

	static int __init
	isl28022_init(void)
	{
	int err;

	isl28022_debugfs_root = debugfs_create_dir("isl28022", NULL);
	err = i2c_add_driver(&isl28022_driver);
	if (!err)
	return 0;

	debugfs_remove_recursive(isl28022_debugfs_root);
	return err;
	}

	static void __exit
	isl28022_exit(void)
	{
	i2c_del_driver(&isl28022_driver);
	debugfs_remove_recursive(isl28022_debugfs_root);
	}

	module_init(isl28022_init);
	module_exit(isl28022_exit);

	MODULE_AUTHOR("Carsten Spieß <mail@carsten-spiess.de>");
	MODULE_DESCRIPTION("ISL28022 driver");
	MODULE_LICENSE("GPL");