drivers/hwmon/tmp421.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /* tmp421.c
  *
  * Copyright (C) 2009 Andre Prendel <andre.prendel@gmx.de>
  * Preliminary support by:
  * Melvin Rook, Raymond Ng
  */

 /*
  * Driver for the Texas Instruments TMP421 SMBus temperature sensor IC.
  * Supported models: TMP421, TMP422, TMP423, TMP441, TMP442
  */

 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/jiffies.h>
 #include <linux/i2c.h>
 #include <linux/hwmon.h>
 #include <linux/hwmon-sysfs.h>
 #include <linux/err.h>
 #include <linux/mutex.h>
 #include <linux/of.h>
 #include <linux/sysfs.h>

 /* Addresses to scan */
 static const unsigned short normal_i2c[] = { 0x2a, 0x4c, 0x4d, 0x4e, 0x4f,
 					     I2C_CLIENT_END };

 enum chips { tmp421, tmp422, tmp423, tmp441, tmp442 };

 #define MAX_CHANNELS				4
 /* The TMP421 registers */
 #define TMP421_STATUS_REG			0x08
 #define TMP421_CONFIG_REG_1			0x09
 #define TMP421_CONFIG_REG_2			0x0A
 #define TMP421_CONFIG_REG_REN(x)		(BIT(3 + (x)))
 #define TMP421_CONFIG_REG_REN_MASK		GENMASK(6, 3)
 #define TMP421_CONVERSION_RATE_REG		0x0B
 #define TMP421_N_FACTOR_REG_1			0x21
 #define TMP421_MANUFACTURER_ID_REG		0xFE
 #define TMP421_DEVICE_ID_REG			0xFF

 static const u8 TMP421_TEMP_MSB[MAX_CHANNELS]	= { 0x00, 0x01, 0x02, 0x03 };
 static const u8 TMP421_TEMP_LSB[MAX_CHANNELS]	= { 0x10, 0x11, 0x12, 0x13 };

 /* Flags */
 #define TMP421_CONFIG_SHUTDOWN			0x40
 #define TMP421_CONFIG_RANGE			0x04

 /* Manufacturer / Device ID's */
 #define TMP421_MANUFACTURER_ID			0x55
 #define TMP421_DEVICE_ID			0x21
 #define TMP422_DEVICE_ID			0x22
 #define TMP423_DEVICE_ID			0x23
 #define TMP441_DEVICE_ID			0x41
 #define TMP442_DEVICE_ID			0x42

 static const struct i2c_device_id tmp421_id[] = {
 	{ "tmp421", 2 },
 	{ "tmp422", 3 },
 	{ "tmp423", 4 },
 	{ "tmp441", 2 },
 	{ "tmp442", 3 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, tmp421_id);

 static const struct of_device_id __maybe_unused tmp421_of_match[] = {
 	{
 		.compatible = "ti,tmp421",
 		.data = (void *)2
 	},
 	{
 		.compatible = "ti,tmp422",
 		.data = (void *)3
 	},
 	{
 		.compatible = "ti,tmp423",
 		.data = (void *)4
 	},
 	{
 		.compatible = "ti,tmp441",
 		.data = (void *)2
 	},
 	{
 		.compatible = "ti,tmp442",
 		.data = (void *)3
 	},
 	{ },
 };
 MODULE_DEVICE_TABLE(of, tmp421_of_match);

 struct tmp421_channel {
 	const char *label;
 	bool enabled;
 	s16 temp;
 };

 struct tmp421_data {
 	struct i2c_client *client;
 	struct mutex update_lock;
 	u32 temp_config[MAX_CHANNELS + 1];
 	struct hwmon_channel_info temp_info;
 	const struct hwmon_channel_info *info[2];
 	struct hwmon_chip_info chip;
 	bool valid;
 	unsigned long last_updated;
 	unsigned long channels;
 	u8 config;
 	struct tmp421_channel channel[MAX_CHANNELS];
 };

 static int temp_from_raw(u16 reg, bool extended)
 {
 	/* Mask out status bits */
 	int temp = reg & ~0xf;

 	if (extended)
 		temp = temp - 64 * 256;
 	else
 		temp = (s16)temp;

 	return DIV_ROUND_CLOSEST(temp * 1000, 256);
 }

 static int tmp421_update_device(struct tmp421_data *data)
 {
 	struct i2c_client *client = data->client;
 	int ret = 0;
 	int i;

 	mutex_lock(&data->update_lock);

 	if (time_after(jiffies, data->last_updated + (HZ / 2)) ||
 	    !data->valid) {
 		ret = i2c_smbus_read_byte_data(client, TMP421_CONFIG_REG_1);
 		if (ret < 0)
 			goto exit;
 		data->config = ret;

 		for (i = 0; i < data->channels; i++) {
 			ret = i2c_smbus_read_byte_data(client, TMP421_TEMP_MSB[i]);
 			if (ret < 0)
 				goto exit;
 			data->channel[i].temp = ret << 8;

 			ret = i2c_smbus_read_byte_data(client, TMP421_TEMP_LSB[i]);
 			if (ret < 0)
 				goto exit;
 			data->channel[i].temp |= ret;
 		}
 		data->last_updated = jiffies;
 		data->valid = true;
 	}

 exit:
 	mutex_unlock(&data->update_lock);

 	if (ret < 0) {
 		data->valid = false;
 		return ret;
 	}

 	return 0;
 }

 static int tmp421_enable_channels(struct tmp421_data *data)
 {
 	int err;
 	struct i2c_client *client = data->client;
 	struct device *dev = &client->dev;
 	int old = i2c_smbus_read_byte_data(client, TMP421_CONFIG_REG_2);
 	int new, i;

 	if (old < 0) {
 		dev_err(dev, "error reading register, can't disable channels\n");
 		return old;
 	}

 	new = old & ~TMP421_CONFIG_REG_REN_MASK;
 	for (i = 0; i < data->channels; i++)
 		if (data->channel[i].enabled)
 			new |= TMP421_CONFIG_REG_REN(i);

 	if (new == old)
 		return 0;

 	err = i2c_smbus_write_byte_data(client, TMP421_CONFIG_REG_2, new);
 	if (err < 0)
 		dev_err(dev, "error writing register, can't disable channels\n");

 	return err;
 }

 static int tmp421_read(struct device *dev, enum hwmon_sensor_types type,
 		       u32 attr, int channel, long *val)
 {
 	struct tmp421_data *tmp421 = dev_get_drvdata(dev);
 	int ret = 0;

 	ret = tmp421_update_device(tmp421);
 	if (ret)
 		return ret;

 	switch (attr) {
 	case hwmon_temp_input:
 		if (!tmp421->channel[channel].enabled)
 			return -ENODATA;
 		*val = temp_from_raw(tmp421->channel[channel].temp,
 				     tmp421->config & TMP421_CONFIG_RANGE);
 		return 0;
 	case hwmon_temp_fault:
 		if (!tmp421->channel[channel].enabled)
 			return -ENODATA;
 		/*
 		 * Any of OPEN or /PVLD bits indicate a hardware mulfunction
 		 * and the conversion result may be incorrect
 		 */
 		*val = !!(tmp421->channel[channel].temp & 0x03);
 		return 0;
 	case hwmon_temp_enable:
 		*val = tmp421->channel[channel].enabled;
 		return 0;
 	default:
 		return -EOPNOTSUPP;
 	}

 }

 static int tmp421_read_string(struct device *dev, enum hwmon_sensor_types type,
 			     u32 attr, int channel, const char **str)
 {
 	struct tmp421_data *data = dev_get_drvdata(dev);

 	*str = data->channel[channel].label;

 	return 0;
 }

 static int tmp421_write(struct device *dev, enum hwmon_sensor_types type,
 			u32 attr, int channel, long val)
 {
 	struct tmp421_data *data = dev_get_drvdata(dev);
 	int ret;

 	switch (attr) {
 	case hwmon_temp_enable:
 		data->channel[channel].enabled = val;
 		ret = tmp421_enable_channels(data);
 		break;
 	default:
 	    ret = -EOPNOTSUPP;
 	}

 	return ret;
 }

 static umode_t tmp421_is_visible(const void *data, enum hwmon_sensor_types type,
 				 u32 attr, int channel)
 {
 	switch (attr) {
 	case hwmon_temp_fault:
 	case hwmon_temp_input:
 		return 0444;
 	case hwmon_temp_label:
 		return 0444;
 	case hwmon_temp_enable:
 		return 0644;
 	default:
 		return 0;
 	}
 }

 static int tmp421_init_client(struct tmp421_data *data)
 {
 	int config, config_orig;
 	struct i2c_client *client = data->client;

 	/* Set the conversion rate to 2 Hz */
 	i2c_smbus_write_byte_data(client, TMP421_CONVERSION_RATE_REG, 0x05);

 	/* Start conversions (disable shutdown if necessary) */
 	config = i2c_smbus_read_byte_data(client, TMP421_CONFIG_REG_1);
 	if (config < 0) {
 		dev_err(&client->dev,
 			"Could not read configuration register (%d)\n", config);
 		return config;
 	}

 	config_orig = config;
 	config &= ~TMP421_CONFIG_SHUTDOWN;

 	if (config != config_orig) {
 		dev_info(&client->dev, "Enable monitoring chip\n");
 		i2c_smbus_write_byte_data(client, TMP421_CONFIG_REG_1, config);
 	}

 	return tmp421_enable_channels(data);
 }

 static int tmp421_detect(struct i2c_client *client,
 			 struct i2c_board_info *info)
 {
 	enum chips kind;
 	struct i2c_adapter *adapter = client->adapter;
 	static const char * const names[] = {
 		"TMP421", "TMP422", "TMP423",
 		"TMP441", "TMP442"
 	};
 	int addr = client->addr;
 	u8 reg;

 	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
 		return -ENODEV;

 	reg = i2c_smbus_read_byte_data(client, TMP421_MANUFACTURER_ID_REG);
 	if (reg != TMP421_MANUFACTURER_ID)
 		return -ENODEV;

 	reg = i2c_smbus_read_byte_data(client, TMP421_CONVERSION_RATE_REG);
 	if (reg & 0xf8)
 		return -ENODEV;

 	reg = i2c_smbus_read_byte_data(client, TMP421_STATUS_REG);
 	if (reg & 0x7f)
 		return -ENODEV;

 	reg = i2c_smbus_read_byte_data(client, TMP421_DEVICE_ID_REG);
 	switch (reg) {
 	case TMP421_DEVICE_ID:
 		kind = tmp421;
 		break;
 	case TMP422_DEVICE_ID:
 		if (addr == 0x2a)
 			return -ENODEV;
 		kind = tmp422;
 		break;
 	case TMP423_DEVICE_ID:
 		if (addr != 0x4c && addr != 0x4d)
 			return -ENODEV;
 		kind = tmp423;
 		break;
 	case TMP441_DEVICE_ID:
 		kind = tmp441;
 		break;
 	case TMP442_DEVICE_ID:
 		if (addr != 0x4c && addr != 0x4d)
 			return -ENODEV;
 		kind = tmp442;
 		break;
 	default:
 		return -ENODEV;
 	}

 	strscpy(info->type, tmp421_id[kind].name, I2C_NAME_SIZE);
 	dev_info(&adapter->dev, "Detected TI %s chip at 0x%02x\n",
 		 names[kind], client->addr);

 	return 0;
 }

 static int tmp421_probe_child_from_dt(struct i2c_client *client,
 				      struct device_node *child,
 				      struct tmp421_data *data)

 {
 	struct device *dev = &client->dev;
 	u32 i;
 	s32 val;
 	int err;

 	err = of_property_read_u32(child, "reg", &i);
 	if (err) {
 		dev_err(dev, "missing reg property of %pOFn\n", child);
 		return err;
 	}

 	if (i >= data->channels) {
 		dev_err(dev, "invalid reg %d of %pOFn\n", i, child);
 		return -EINVAL;
 	}

 	of_property_read_string(child, "label", &data->channel[i].label);
 	if (data->channel[i].label)
 		data->temp_config[i] |= HWMON_T_LABEL;

 	data->channel[i].enabled = of_device_is_available(child);

 	err = of_property_read_s32(child, "ti,n-factor", &val);
 	if (!err) {
 		if (i == 0) {
 			dev_err(dev, "n-factor can't be set for internal channel\n");
 			return -EINVAL;
 		}

 		if (val > 127 || val < -128) {
 			dev_err(dev, "n-factor for channel %d invalid (%d)\n",
 				i, val);
 			return -EINVAL;
 		}
 		i2c_smbus_write_byte_data(client, TMP421_N_FACTOR_REG_1 + i - 1,
 					  val);
 	}

 	return 0;
 }

 static int tmp421_probe_from_dt(struct i2c_client *client, struct tmp421_data *data)
 {
 	struct device *dev = &client->dev;
 	const struct device_node *np = dev->of_node;
 	struct device_node *child;
 	int err;

 	for_each_child_of_node(np, child) {
 		if (strcmp(child->name, "channel"))
 			continue;

 		err = tmp421_probe_child_from_dt(client, child, data);
 		if (err) {
 			of_node_put(child);
 			return err;
 		}
 	}

 	return 0;
 }

 static const struct hwmon_ops tmp421_ops = {
 	.is_visible = tmp421_is_visible,
 	.read = tmp421_read,
 	.read_string = tmp421_read_string,
 	.write = tmp421_write,
 };

 static int tmp421_probe(struct i2c_client *client)
 {
 	struct device *dev = &client->dev;
 	struct device *hwmon_dev;
 	struct tmp421_data *data;
 	int i, err;

 	data = devm_kzalloc(dev, sizeof(struct tmp421_data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;

 	mutex_init(&data->update_lock);
 	data->channels = (unsigned long)i2c_get_match_data(client);
 	data->client = client;

 	for (i = 0; i < data->channels; i++) {
 		data->temp_config[i] = HWMON_T_INPUT | HWMON_T_FAULT | HWMON_T_ENABLE;
 		data->channel[i].enabled = true;
 	}

 	err = tmp421_probe_from_dt(client, data);
 	if (err)
 		return err;

 	err = tmp421_init_client(data);
 	if (err)
 		return err;

 	data->chip.ops = &tmp421_ops;
 	data->chip.info = data->info;

 	data->info[0] = &data->temp_info;

 	data->temp_info.type = hwmon_temp;
 	data->temp_info.config = data->temp_config;

 	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
 							 data,
 							 &data->chip,
 							 NULL);
 	return PTR_ERR_OR_ZERO(hwmon_dev);
 }

 static struct i2c_driver tmp421_driver = {
 	.class = I2C_CLASS_HWMON,
 	.driver = {
 		.name	= "tmp421",
 		.of_match_table = of_match_ptr(tmp421_of_match),
 	},
 	.probe = tmp421_probe,
 	.id_table = tmp421_id,
 	.detect = tmp421_detect,
 	.address_list = normal_i2c,
 };

 module_i2c_driver(tmp421_driver);

 MODULE_AUTHOR("Andre Prendel <andre.prendel@gmx.de>");
 MODULE_DESCRIPTION("Texas Instruments TMP421/422/423/441/442 temperature sensor driver");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/* tmp421.c
	*
	* Copyright (C) 2009 Andre Prendel <andre.prendel@gmx.de>
	* Preliminary support by:
	* Melvin Rook, Raymond Ng
	*/

	/*
	* Driver for the Texas Instruments TMP421 SMBus temperature sensor IC.
	* Supported models: TMP421, TMP422, TMP423, TMP441, TMP442
	*/

	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/slab.h>
	#include <linux/jiffies.h>
	#include <linux/i2c.h>
	#include <linux/hwmon.h>
	#include <linux/hwmon-sysfs.h>
	#include <linux/err.h>
	#include <linux/mutex.h>
	#include <linux/of.h>
	#include <linux/sysfs.h>

	/* Addresses to scan */
	static const unsigned short normal_i2c[] = { 0x2a, 0x4c, 0x4d, 0x4e, 0x4f,
	I2C_CLIENT_END };

	enum chips { tmp421, tmp422, tmp423, tmp441, tmp442 };

	#define MAX_CHANNELS 4
	/* The TMP421 registers */
	#define TMP421_STATUS_REG 0x08
	#define TMP421_CONFIG_REG_1 0x09
	#define TMP421_CONFIG_REG_2 0x0A
	#define TMP421_CONFIG_REG_REN(x) (BIT(3 + (x)))
	#define TMP421_CONFIG_REG_REN_MASK GENMASK(6, 3)
	#define TMP421_CONVERSION_RATE_REG 0x0B
	#define TMP421_N_FACTOR_REG_1 0x21
	#define TMP421_MANUFACTURER_ID_REG 0xFE
	#define TMP421_DEVICE_ID_REG 0xFF

	static const u8 TMP421_TEMP_MSB[MAX_CHANNELS] = { 0x00, 0x01, 0x02, 0x03 };
	static const u8 TMP421_TEMP_LSB[MAX_CHANNELS] = { 0x10, 0x11, 0x12, 0x13 };

	/* Flags */
	#define TMP421_CONFIG_SHUTDOWN 0x40
	#define TMP421_CONFIG_RANGE 0x04

	/* Manufacturer / Device ID's */
	#define TMP421_MANUFACTURER_ID 0x55
	#define TMP421_DEVICE_ID 0x21
	#define TMP422_DEVICE_ID 0x22
	#define TMP423_DEVICE_ID 0x23
	#define TMP441_DEVICE_ID 0x41
	#define TMP442_DEVICE_ID 0x42

	static const struct i2c_device_id tmp421_id[] = {
	{ "tmp421", 2 },
	{ "tmp422", 3 },
	{ "tmp423", 4 },
	{ "tmp441", 2 },
	{ "tmp442", 3 },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, tmp421_id);

	static const struct of_device_id __maybe_unused tmp421_of_match[] = {
	{
	.compatible = "ti,tmp421",
	.data = (void *)2
	},
	{
	.compatible = "ti,tmp422",
	.data = (void *)3
	},
	{
	.compatible = "ti,tmp423",
	.data = (void *)4
	},
	{
	.compatible = "ti,tmp441",
	.data = (void *)2
	},
	{
	.compatible = "ti,tmp442",
	.data = (void *)3
	},
	{ },
	};
	MODULE_DEVICE_TABLE(of, tmp421_of_match);

	struct tmp421_channel {
	const char *label;
	bool enabled;
	s16 temp;
	};

	struct tmp421_data {
	struct i2c_client *client;
	struct mutex update_lock;
	u32 temp_config[MAX_CHANNELS + 1];
	struct hwmon_channel_info temp_info;
	const struct hwmon_channel_info *info[2];
	struct hwmon_chip_info chip;
	bool valid;
	unsigned long last_updated;
	unsigned long channels;
	u8 config;
	struct tmp421_channel channel[MAX_CHANNELS];
	};

	static int temp_from_raw(u16 reg, bool extended)
	{
	/* Mask out status bits */
	int temp = reg & ~0xf;

	if (extended)
	temp = temp - 64 * 256;
	else
	temp = (s16)temp;

	return DIV_ROUND_CLOSEST(temp * 1000, 256);
	}

	static int tmp421_update_device(struct tmp421_data *data)
	{
	struct i2c_client *client = data->client;
	int ret = 0;
	int i;

	mutex_lock(&data->update_lock);

	if (time_after(jiffies, data->last_updated + (HZ / 2)) \|\|
	!data->valid) {
	ret = i2c_smbus_read_byte_data(client, TMP421_CONFIG_REG_1);
	if (ret < 0)
	goto exit;
	data->config = ret;

	for (i = 0; i < data->channels; i++) {
	ret = i2c_smbus_read_byte_data(client, TMP421_TEMP_MSB[i]);
	if (ret < 0)
	goto exit;
	data->channel[i].temp = ret << 8;

	ret = i2c_smbus_read_byte_data(client, TMP421_TEMP_LSB[i]);
	if (ret < 0)
	goto exit;
	data->channel[i].temp \|= ret;
	}
	data->last_updated = jiffies;
	data->valid = true;
	}

	exit:
	mutex_unlock(&data->update_lock);

	if (ret < 0) {
	data->valid = false;
	return ret;
	}

	return 0;
	}

	static int tmp421_enable_channels(struct tmp421_data *data)
	{
	int err;
	struct i2c_client *client = data->client;
	struct device *dev = &client->dev;
	int old = i2c_smbus_read_byte_data(client, TMP421_CONFIG_REG_2);
	int new, i;

	if (old < 0) {
	dev_err(dev, "error reading register, can't disable channels\n");
	return old;
	}

	new = old & ~TMP421_CONFIG_REG_REN_MASK;
	for (i = 0; i < data->channels; i++)
	if (data->channel[i].enabled)
	new \|= TMP421_CONFIG_REG_REN(i);

	if (new == old)
	return 0;

	err = i2c_smbus_write_byte_data(client, TMP421_CONFIG_REG_2, new);
	if (err < 0)
	dev_err(dev, "error writing register, can't disable channels\n");

	return err;
	}

	static int tmp421_read(struct device *dev, enum hwmon_sensor_types type,
	u32 attr, int channel, long *val)
	{
	struct tmp421_data *tmp421 = dev_get_drvdata(dev);
	int ret = 0;

	ret = tmp421_update_device(tmp421);
	if (ret)
	return ret;

	switch (attr) {
	case hwmon_temp_input:
	if (!tmp421->channel[channel].enabled)
	return -ENODATA;
	*val = temp_from_raw(tmp421->channel[channel].temp,
	tmp421->config & TMP421_CONFIG_RANGE);
	return 0;
	case hwmon_temp_fault:
	if (!tmp421->channel[channel].enabled)
	return -ENODATA;
	/*
	* Any of OPEN or /PVLD bits indicate a hardware mulfunction
	* and the conversion result may be incorrect
	*/
	*val = !!(tmp421->channel[channel].temp & 0x03);
	return 0;
	case hwmon_temp_enable:
	*val = tmp421->channel[channel].enabled;
	return 0;
	default:
	return -EOPNOTSUPP;
	}

	}

	static int tmp421_read_string(struct device *dev, enum hwmon_sensor_types type,
	u32 attr, int channel, const char **str)
	{
	struct tmp421_data *data = dev_get_drvdata(dev);

	*str = data->channel[channel].label;

	return 0;
	}

	static int tmp421_write(struct device *dev, enum hwmon_sensor_types type,
	u32 attr, int channel, long val)
	{
	struct tmp421_data *data = dev_get_drvdata(dev);
	int ret;

	switch (attr) {
	case hwmon_temp_enable:
	data->channel[channel].enabled = val;
	ret = tmp421_enable_channels(data);
	break;
	default:
	ret = -EOPNOTSUPP;
	}

	return ret;
	}

	static umode_t tmp421_is_visible(const void *data, enum hwmon_sensor_types type,
	u32 attr, int channel)
	{
	switch (attr) {
	case hwmon_temp_fault:
	case hwmon_temp_input:
	return 0444;
	case hwmon_temp_label:
	return 0444;
	case hwmon_temp_enable:
	return 0644;
	default:
	return 0;
	}
	}

	static int tmp421_init_client(struct tmp421_data *data)
	{
	int config, config_orig;
	struct i2c_client *client = data->client;

	/* Set the conversion rate to 2 Hz */
	i2c_smbus_write_byte_data(client, TMP421_CONVERSION_RATE_REG, 0x05);

	/* Start conversions (disable shutdown if necessary) */
	config = i2c_smbus_read_byte_data(client, TMP421_CONFIG_REG_1);
	if (config < 0) {
	dev_err(&client->dev,
	"Could not read configuration register (%d)\n", config);
	return config;
	}

	config_orig = config;
	config &= ~TMP421_CONFIG_SHUTDOWN;

	if (config != config_orig) {
	dev_info(&client->dev, "Enable monitoring chip\n");
	i2c_smbus_write_byte_data(client, TMP421_CONFIG_REG_1, config);
	}

	return tmp421_enable_channels(data);
	}

	static int tmp421_detect(struct i2c_client *client,
	struct i2c_board_info *info)
	{
	enum chips kind;
	struct i2c_adapter *adapter = client->adapter;
	static const char * const names[] = {
	"TMP421", "TMP422", "TMP423",
	"TMP441", "TMP442"
	};
	int addr = client->addr;
	u8 reg;

	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
	return -ENODEV;

	reg = i2c_smbus_read_byte_data(client, TMP421_MANUFACTURER_ID_REG);
	if (reg != TMP421_MANUFACTURER_ID)
	return -ENODEV;

	reg = i2c_smbus_read_byte_data(client, TMP421_CONVERSION_RATE_REG);
	if (reg & 0xf8)
	return -ENODEV;

	reg = i2c_smbus_read_byte_data(client, TMP421_STATUS_REG);
	if (reg & 0x7f)
	return -ENODEV;

	reg = i2c_smbus_read_byte_data(client, TMP421_DEVICE_ID_REG);
	switch (reg) {
	case TMP421_DEVICE_ID:
	kind = tmp421;
	break;
	case TMP422_DEVICE_ID:
	if (addr == 0x2a)
	return -ENODEV;
	kind = tmp422;
	break;
	case TMP423_DEVICE_ID:
	if (addr != 0x4c && addr != 0x4d)
	return -ENODEV;
	kind = tmp423;
	break;
	case TMP441_DEVICE_ID:
	kind = tmp441;
	break;
	case TMP442_DEVICE_ID:
	if (addr != 0x4c && addr != 0x4d)
	return -ENODEV;
	kind = tmp442;
	break;
	default:
	return -ENODEV;
	}

	strscpy(info->type, tmp421_id[kind].name, I2C_NAME_SIZE);
	dev_info(&adapter->dev, "Detected TI %s chip at 0x%02x\n",
	names[kind], client->addr);

	return 0;
	}

	static int tmp421_probe_child_from_dt(struct i2c_client *client,
	struct device_node *child,
	struct tmp421_data *data)

	{
	struct device *dev = &client->dev;
	u32 i;
	s32 val;
	int err;

	err = of_property_read_u32(child, "reg", &i);
	if (err) {
	dev_err(dev, "missing reg property of %pOFn\n", child);
	return err;
	}

	if (i >= data->channels) {
	dev_err(dev, "invalid reg %d of %pOFn\n", i, child);
	return -EINVAL;
	}

	of_property_read_string(child, "label", &data->channel[i].label);
	if (data->channel[i].label)
	data->temp_config[i] \|= HWMON_T_LABEL;

	data->channel[i].enabled = of_device_is_available(child);

	err = of_property_read_s32(child, "ti,n-factor", &val);
	if (!err) {
	if (i == 0) {
	dev_err(dev, "n-factor can't be set for internal channel\n");
	return -EINVAL;
	}

	if (val > 127 \|\| val < -128) {
	dev_err(dev, "n-factor for channel %d invalid (%d)\n",
	i, val);
	return -EINVAL;
	}
	i2c_smbus_write_byte_data(client, TMP421_N_FACTOR_REG_1 + i - 1,
	val);
	}

	return 0;
	}

	static int tmp421_probe_from_dt(struct i2c_client client, struct tmp421_data data)
	{
	struct device *dev = &client->dev;
	const struct device_node *np = dev->of_node;
	struct device_node *child;
	int err;

	for_each_child_of_node(np, child) {
	if (strcmp(child->name, "channel"))
	continue;

	err = tmp421_probe_child_from_dt(client, child, data);
	if (err) {
	of_node_put(child);
	return err;
	}
	}

	return 0;
	}

	static const struct hwmon_ops tmp421_ops = {
	.is_visible = tmp421_is_visible,
	.read = tmp421_read,
	.read_string = tmp421_read_string,
	.write = tmp421_write,
	};

	static int tmp421_probe(struct i2c_client *client)
	{
	struct device *dev = &client->dev;
	struct device *hwmon_dev;
	struct tmp421_data *data;
	int i, err;

	data = devm_kzalloc(dev, sizeof(struct tmp421_data), GFP_KERNEL);
	if (!data)
	return -ENOMEM;

	mutex_init(&data->update_lock);
	data->channels = (unsigned long)i2c_get_match_data(client);
	data->client = client;

	for (i = 0; i < data->channels; i++) {
	data->temp_config[i] = HWMON_T_INPUT \| HWMON_T_FAULT \| HWMON_T_ENABLE;
	data->channel[i].enabled = true;
	}

	err = tmp421_probe_from_dt(client, data);
	if (err)
	return err;

	err = tmp421_init_client(data);
	if (err)
	return err;

	data->chip.ops = &tmp421_ops;
	data->chip.info = data->info;

	data->info[0] = &data->temp_info;

	data->temp_info.type = hwmon_temp;
	data->temp_info.config = data->temp_config;

	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
	data,
	&data->chip,
	NULL);
	return PTR_ERR_OR_ZERO(hwmon_dev);
	}

	static struct i2c_driver tmp421_driver = {
	.class = I2C_CLASS_HWMON,
	.driver = {
	.name = "tmp421",
	.of_match_table = of_match_ptr(tmp421_of_match),
	},
	.probe = tmp421_probe,
	.id_table = tmp421_id,
	.detect = tmp421_detect,
	.address_list = normal_i2c,
	};

	module_i2c_driver(tmp421_driver);

	MODULE_AUTHOR("Andre Prendel <andre.prendel@gmx.de>");
	MODULE_DESCRIPTION("Texas Instruments TMP421/422/423/441/442 temperature sensor driver");
	MODULE_LICENSE("GPL");