drivers/hwmon/max31730.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Driver for MAX31730 3-Channel Remote Temperature Sensor
  *
  * Copyright (c) 2019 Guenter Roeck <linux@roeck-us.net>
  */

 #include <linux/bits.h>
 #include <linux/err.h>
 #include <linux/i2c.h>
 #include <linux/init.h>
 #include <linux/hwmon.h>
 #include <linux/module.h>
 #include <linux/of_device.h>
 #include <linux/of.h>
 #include <linux/slab.h>

 /* Addresses scanned */
 static const unsigned short normal_i2c[] = { 0x1c, 0x1d, 0x1e, 0x1f, 0x4c,
 					     0x4d, 0x4e, 0x4f, I2C_CLIENT_END };

 /* The MAX31730 registers */
 #define MAX31730_REG_TEMP		0x00
 #define MAX31730_REG_CONF		0x13
 #define  MAX31730_STOP			BIT(7)
 #define  MAX31730_EXTRANGE		BIT(1)
 #define MAX31730_REG_TEMP_OFFSET	0x16
 #define  MAX31730_TEMP_OFFSET_BASELINE	0x77
 #define MAX31730_REG_OFFSET_ENABLE	0x17
 #define MAX31730_REG_TEMP_MAX		0x20
 #define MAX31730_REG_TEMP_MIN		0x30
 #define MAX31730_REG_STATUS_HIGH	0x32
 #define MAX31730_REG_STATUS_LOW		0x33
 #define MAX31730_REG_CHANNEL_ENABLE	0x35
 #define MAX31730_REG_TEMP_FAULT		0x36

 #define MAX31730_REG_MFG_ID		0x50
 #define  MAX31730_MFG_ID		0x4d
 #define MAX31730_REG_MFG_REV		0x51
 #define  MAX31730_MFG_REV		0x01

 #define MAX31730_TEMP_MIN		(-128000)
 #define MAX31730_TEMP_MAX		127937

 /* Each client has this additional data */
 struct max31730_data {
 	struct i2c_client	*client;
 	u8			orig_conf;
 	u8			current_conf;
 	u8			offset_enable;
 	u8			channel_enable;
 };

 /*-----------------------------------------------------------------------*/

 static inline long max31730_reg_to_mc(s16 temp)
 {
 	return DIV_ROUND_CLOSEST((temp >> 4) * 1000, 16);
 }

 static int max31730_write_config(struct max31730_data *data, u8 set_mask,
 				 u8 clr_mask)
 {
 	u8 value;

 	clr_mask |= MAX31730_EXTRANGE;
 	value = data->current_conf & ~clr_mask;
 	value |= set_mask;

 	if (data->current_conf != value) {
 		s32 err;

 		err = i2c_smbus_write_byte_data(data->client, MAX31730_REG_CONF,
 						value);
 		if (err)
 			return err;
 		data->current_conf = value;
 	}
 	return 0;
 }

 static int max31730_set_enable(struct i2c_client *client, int reg,
 			       u8 *confdata, int channel, bool enable)
 {
 	u8 regval = *confdata;
 	int err;

 	if (enable)
 		regval |= BIT(channel);
 	else
 		regval &= ~BIT(channel);

 	if (regval != *confdata) {
 		err = i2c_smbus_write_byte_data(client, reg, regval);
 		if (err)
 			return err;
 		*confdata = regval;
 	}
 	return 0;
 }

 static int max31730_set_offset_enable(struct max31730_data *data, int channel,
 				      bool enable)
 {
 	return max31730_set_enable(data->client, MAX31730_REG_OFFSET_ENABLE,
 				   &data->offset_enable, channel, enable);
 }

 static int max31730_set_channel_enable(struct max31730_data *data, int channel,
 				       bool enable)
 {
 	return max31730_set_enable(data->client, MAX31730_REG_CHANNEL_ENABLE,
 				   &data->channel_enable, channel, enable);
 }

 static int max31730_read(struct device *dev, enum hwmon_sensor_types type,
 			 u32 attr, int channel, long *val)
 {
 	struct max31730_data *data = dev_get_drvdata(dev);
 	int regval, reg, offset;

 	if (type != hwmon_temp)
 		return -EINVAL;

 	switch (attr) {
 	case hwmon_temp_input:
 		if (!(data->channel_enable & BIT(channel)))
 			return -ENODATA;
 		reg = MAX31730_REG_TEMP + (channel * 2);
 		break;
 	case hwmon_temp_max:
 		reg = MAX31730_REG_TEMP_MAX + (channel * 2);
 		break;
 	case hwmon_temp_min:
 		reg = MAX31730_REG_TEMP_MIN;
 		break;
 	case hwmon_temp_enable:
 		*val = !!(data->channel_enable & BIT(channel));
 		return 0;
 	case hwmon_temp_offset:
 		if (!channel)
 			return -EINVAL;
 		if (!(data->offset_enable & BIT(channel))) {
 			*val = 0;
 			return 0;
 		}
 		offset = i2c_smbus_read_byte_data(data->client,
 						  MAX31730_REG_TEMP_OFFSET);
 		if (offset < 0)
 			return offset;
 		*val = (offset - MAX31730_TEMP_OFFSET_BASELINE) * 125;
 		return 0;
 	case hwmon_temp_fault:
 		regval = i2c_smbus_read_byte_data(data->client,
 						  MAX31730_REG_TEMP_FAULT);
 		if (regval < 0)
 			return regval;
 		*val = !!(regval & BIT(channel));
 		return 0;
 	case hwmon_temp_min_alarm:
 		regval = i2c_smbus_read_byte_data(data->client,
 						  MAX31730_REG_STATUS_LOW);
 		if (regval < 0)
 			return regval;
 		*val = !!(regval & BIT(channel));
 		return 0;
 	case hwmon_temp_max_alarm:
 		regval = i2c_smbus_read_byte_data(data->client,
 						  MAX31730_REG_STATUS_HIGH);
 		if (regval < 0)
 			return regval;
 		*val = !!(regval & BIT(channel));
 		return 0;
 	default:
 		return -EINVAL;
 	}
 	regval = i2c_smbus_read_word_swapped(data->client, reg);
 	if (regval < 0)
 		return regval;

 	*val = max31730_reg_to_mc(regval);

 	return 0;
 }

 static int max31730_write(struct device *dev, enum hwmon_sensor_types type,
 			  u32 attr, int channel, long val)
 {
 	struct max31730_data *data = dev_get_drvdata(dev);
 	int reg, err;

 	if (type != hwmon_temp)
 		return -EINVAL;

 	switch (attr) {
 	case hwmon_temp_max:
 		reg = MAX31730_REG_TEMP_MAX + channel * 2;
 		break;
 	case hwmon_temp_min:
 		reg = MAX31730_REG_TEMP_MIN;
 		break;
 	case hwmon_temp_enable:
 		if (val != 0 && val != 1)
 			return -EINVAL;
 		return max31730_set_channel_enable(data, channel, val);
 	case hwmon_temp_offset:
 		val = clamp_val(val, -14875, 17000) + 14875;
 		val = DIV_ROUND_CLOSEST(val, 125);
 		err = max31730_set_offset_enable(data, channel,
 					val != MAX31730_TEMP_OFFSET_BASELINE);
 		if (err)
 			return err;
 		return i2c_smbus_write_byte_data(data->client,
 						 MAX31730_REG_TEMP_OFFSET, val);
 	default:
 		return -EINVAL;
 	}

 	val = clamp_val(val, MAX31730_TEMP_MIN, MAX31730_TEMP_MAX);
 	val = DIV_ROUND_CLOSEST(val << 4, 1000) << 4;

 	return i2c_smbus_write_word_swapped(data->client, reg, (u16)val);
 }

 static umode_t max31730_is_visible(const void *data,
 				   enum hwmon_sensor_types type,
 				   u32 attr, int channel)
 {
 	switch (type) {
 	case hwmon_temp:
 		switch (attr) {
 		case hwmon_temp_input:
 		case hwmon_temp_min_alarm:
 		case hwmon_temp_max_alarm:
 		case hwmon_temp_fault:
 			return 0444;
 		case hwmon_temp_min:
 			return channel ? 0444 : 0644;
 		case hwmon_temp_offset:
 		case hwmon_temp_enable:
 		case hwmon_temp_max:
 			return 0644;
 		}
 		break;
 	default:
 		break;
 	}
 	return 0;
 }

 static const struct hwmon_channel_info *max31730_info[] = {
 	HWMON_CHANNEL_INFO(chip,
 			   HWMON_C_REGISTER_TZ),
 	HWMON_CHANNEL_INFO(temp,
 			   HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX |
 			   HWMON_T_ENABLE |
 			   HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM,
 			   HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX |
 			   HWMON_T_OFFSET | HWMON_T_ENABLE |
 			   HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM |
 			   HWMON_T_FAULT,
 			   HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX |
 			   HWMON_T_OFFSET | HWMON_T_ENABLE |
 			   HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM |
 			   HWMON_T_FAULT,
 			   HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX |
 			   HWMON_T_OFFSET | HWMON_T_ENABLE |
 			   HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM |
 			   HWMON_T_FAULT
 			   ),
 	NULL
 };

 static const struct hwmon_ops max31730_hwmon_ops = {
 	.is_visible = max31730_is_visible,
 	.read = max31730_read,
 	.write = max31730_write,
 };

 static const struct hwmon_chip_info max31730_chip_info = {
 	.ops = &max31730_hwmon_ops,
 	.info = max31730_info,
 };

 static void max31730_remove(void *data)
 {
 	struct max31730_data *max31730 = data;
 	struct i2c_client *client = max31730->client;

 	i2c_smbus_write_byte_data(client, MAX31730_REG_CONF,
 				  max31730->orig_conf);
 }

 static int
 max31730_probe(struct i2c_client *client, const struct i2c_device_id *id)
 {
 	struct device *dev = &client->dev;
 	struct device *hwmon_dev;
 	struct max31730_data *data;
 	int status, err;

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

 	data = devm_kzalloc(dev, sizeof(struct max31730_data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;

 	data->client = client;

 	/* Cache original configuration and enable status */
 	status = i2c_smbus_read_byte_data(client, MAX31730_REG_CHANNEL_ENABLE);
 	if (status < 0)
 		return status;
 	data->channel_enable = status;

 	status = i2c_smbus_read_byte_data(client, MAX31730_REG_OFFSET_ENABLE);
 	if (status < 0)
 		return status;
 	data->offset_enable = status;

 	status = i2c_smbus_read_byte_data(client, MAX31730_REG_CONF);
 	if (status < 0)
 		return status;
 	data->orig_conf = status;
 	data->current_conf = status;

 	err = max31730_write_config(data,
 				    data->channel_enable ? 0 : MAX31730_STOP,
 				    data->channel_enable ? MAX31730_STOP : 0);
 	if (err)
 		return err;

 	dev_set_drvdata(dev, data);

 	err = devm_add_action_or_reset(dev, max31730_remove, data);
 	if (err)
 		return err;

 	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
 							 data,
 							 &max31730_chip_info,
 							 NULL);
 	return PTR_ERR_OR_ZERO(hwmon_dev);
 }

 static const struct i2c_device_id max31730_ids[] = {
 	{ "max31730", 0, },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, max31730_ids);

 static const struct of_device_id __maybe_unused max31730_of_match[] = {
 	{
 		.compatible = "maxim,max31730",
 	},
 	{ },
 };
 MODULE_DEVICE_TABLE(of, max31730_of_match);

 static bool max31730_check_reg_temp(struct i2c_client *client,
 				    int reg)
 {
 	int regval;

 	regval = i2c_smbus_read_byte_data(client, reg + 1);
 	return regval < 0 || (regval & 0x0f);
 }

 /* Return 0 if detection is successful, -ENODEV otherwise */
 static int max31730_detect(struct i2c_client *client,
 			   struct i2c_board_info *info)
 {
 	struct i2c_adapter *adapter = client->adapter;
 	int regval;
 	int i;

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

 	regval = i2c_smbus_read_byte_data(client, MAX31730_REG_MFG_ID);
 	if (regval != MAX31730_MFG_ID)
 		return -ENODEV;
 	regval = i2c_smbus_read_byte_data(client, MAX31730_REG_MFG_REV);
 	if (regval != MAX31730_MFG_REV)
 		return -ENODEV;

 	/* lower 4 bit of temperature and limit registers must be 0 */
 	if (max31730_check_reg_temp(client, MAX31730_REG_TEMP_MIN))
 		return -ENODEV;

 	for (i = 0; i < 4; i++) {
 		if (max31730_check_reg_temp(client, MAX31730_REG_TEMP + i * 2))
 			return -ENODEV;
 		if (max31730_check_reg_temp(client,
 					    MAX31730_REG_TEMP_MAX + i * 2))
 			return -ENODEV;
 	}

 	strlcpy(info->type, "max31730", I2C_NAME_SIZE);

 	return 0;
 }

 static int __maybe_unused max31730_suspend(struct device *dev)
 {
 	struct max31730_data *data = dev_get_drvdata(dev);

 	return max31730_write_config(data, MAX31730_STOP, 0);
 }

 static int __maybe_unused max31730_resume(struct device *dev)
 {
 	struct max31730_data *data = dev_get_drvdata(dev);

 	return max31730_write_config(data, 0, MAX31730_STOP);
 }

 static SIMPLE_DEV_PM_OPS(max31730_pm_ops, max31730_suspend, max31730_resume);

 static struct i2c_driver max31730_driver = {
 	.class		= I2C_CLASS_HWMON,
 	.driver = {
 		.name	= "max31730",
 		.of_match_table = of_match_ptr(max31730_of_match),
 		.pm	= &max31730_pm_ops,
 	},
 	.probe		= max31730_probe,
 	.id_table	= max31730_ids,
 	.detect		= max31730_detect,
 	.address_list	= normal_i2c,
 };

 module_i2c_driver(max31730_driver);

 MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
 MODULE_DESCRIPTION("MAX31730 driver");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* Driver for MAX31730 3-Channel Remote Temperature Sensor
	*
	* Copyright (c) 2019 Guenter Roeck <linux@roeck-us.net>
	*/

	#include <linux/bits.h>
	#include <linux/err.h>
	#include <linux/i2c.h>
	#include <linux/init.h>
	#include <linux/hwmon.h>
	#include <linux/module.h>
	#include <linux/of_device.h>
	#include <linux/of.h>
	#include <linux/slab.h>

	/* Addresses scanned */
	static const unsigned short normal_i2c[] = { 0x1c, 0x1d, 0x1e, 0x1f, 0x4c,
	0x4d, 0x4e, 0x4f, I2C_CLIENT_END };

	/* The MAX31730 registers */
	#define MAX31730_REG_TEMP 0x00
	#define MAX31730_REG_CONF 0x13
	#define MAX31730_STOP BIT(7)
	#define MAX31730_EXTRANGE BIT(1)
	#define MAX31730_REG_TEMP_OFFSET 0x16
	#define MAX31730_TEMP_OFFSET_BASELINE 0x77
	#define MAX31730_REG_OFFSET_ENABLE 0x17
	#define MAX31730_REG_TEMP_MAX 0x20
	#define MAX31730_REG_TEMP_MIN 0x30
	#define MAX31730_REG_STATUS_HIGH 0x32
	#define MAX31730_REG_STATUS_LOW 0x33
	#define MAX31730_REG_CHANNEL_ENABLE 0x35
	#define MAX31730_REG_TEMP_FAULT 0x36

	#define MAX31730_REG_MFG_ID 0x50
	#define MAX31730_MFG_ID 0x4d
	#define MAX31730_REG_MFG_REV 0x51
	#define MAX31730_MFG_REV 0x01

	#define MAX31730_TEMP_MIN (-128000)
	#define MAX31730_TEMP_MAX 127937

	/* Each client has this additional data */
	struct max31730_data {
	struct i2c_client *client;
	u8 orig_conf;
	u8 current_conf;
	u8 offset_enable;
	u8 channel_enable;
	};

	/-----------------------------------------------------------------------/

	static inline long max31730_reg_to_mc(s16 temp)
	{
	return DIV_ROUND_CLOSEST((temp >> 4) * 1000, 16);
	}

	static int max31730_write_config(struct max31730_data *data, u8 set_mask,
	u8 clr_mask)
	{
	u8 value;

	clr_mask \|= MAX31730_EXTRANGE;
	value = data->current_conf & ~clr_mask;
	value \|= set_mask;

	if (data->current_conf != value) {
	s32 err;

	err = i2c_smbus_write_byte_data(data->client, MAX31730_REG_CONF,
	value);
	if (err)
	return err;
	data->current_conf = value;
	}
	return 0;
	}

	static int max31730_set_enable(struct i2c_client *client, int reg,
	u8 *confdata, int channel, bool enable)
	{
	u8 regval = *confdata;
	int err;

	if (enable)
	regval \|= BIT(channel);
	else
	regval &= ~BIT(channel);

	if (regval != *confdata) {
	err = i2c_smbus_write_byte_data(client, reg, regval);
	if (err)
	return err;
	*confdata = regval;
	}
	return 0;
	}

	static int max31730_set_offset_enable(struct max31730_data *data, int channel,
	bool enable)
	{
	return max31730_set_enable(data->client, MAX31730_REG_OFFSET_ENABLE,
	&data->offset_enable, channel, enable);
	}

	static int max31730_set_channel_enable(struct max31730_data *data, int channel,
	bool enable)
	{
	return max31730_set_enable(data->client, MAX31730_REG_CHANNEL_ENABLE,
	&data->channel_enable, channel, enable);
	}

	static int max31730_read(struct device *dev, enum hwmon_sensor_types type,
	u32 attr, int channel, long *val)
	{
	struct max31730_data *data = dev_get_drvdata(dev);
	int regval, reg, offset;

	if (type != hwmon_temp)
	return -EINVAL;

	switch (attr) {
	case hwmon_temp_input:
	if (!(data->channel_enable & BIT(channel)))
	return -ENODATA;
	reg = MAX31730_REG_TEMP + (channel * 2);
	break;
	case hwmon_temp_max:
	reg = MAX31730_REG_TEMP_MAX + (channel * 2);
	break;
	case hwmon_temp_min:
	reg = MAX31730_REG_TEMP_MIN;
	break;
	case hwmon_temp_enable:
	*val = !!(data->channel_enable & BIT(channel));
	return 0;
	case hwmon_temp_offset:
	if (!channel)
	return -EINVAL;
	if (!(data->offset_enable & BIT(channel))) {
	*val = 0;
	return 0;
	}
	offset = i2c_smbus_read_byte_data(data->client,
	MAX31730_REG_TEMP_OFFSET);
	if (offset < 0)
	return offset;
	val = (offset - MAX31730_TEMP_OFFSET_BASELINE) 125;
	return 0;
	case hwmon_temp_fault:
	regval = i2c_smbus_read_byte_data(data->client,
	MAX31730_REG_TEMP_FAULT);
	if (regval < 0)
	return regval;
	*val = !!(regval & BIT(channel));
	return 0;
	case hwmon_temp_min_alarm:
	regval = i2c_smbus_read_byte_data(data->client,
	MAX31730_REG_STATUS_LOW);
	if (regval < 0)
	return regval;
	*val = !!(regval & BIT(channel));
	return 0;
	case hwmon_temp_max_alarm:
	regval = i2c_smbus_read_byte_data(data->client,
	MAX31730_REG_STATUS_HIGH);
	if (regval < 0)
	return regval;
	*val = !!(regval & BIT(channel));
	return 0;
	default:
	return -EINVAL;
	}
	regval = i2c_smbus_read_word_swapped(data->client, reg);
	if (regval < 0)
	return regval;

	*val = max31730_reg_to_mc(regval);

	return 0;
	}

	static int max31730_write(struct device *dev, enum hwmon_sensor_types type,
	u32 attr, int channel, long val)
	{
	struct max31730_data *data = dev_get_drvdata(dev);
	int reg, err;

	if (type != hwmon_temp)
	return -EINVAL;

	switch (attr) {
	case hwmon_temp_max:
	reg = MAX31730_REG_TEMP_MAX + channel * 2;
	break;
	case hwmon_temp_min:
	reg = MAX31730_REG_TEMP_MIN;
	break;
	case hwmon_temp_enable:
	if (val != 0 && val != 1)
	return -EINVAL;
	return max31730_set_channel_enable(data, channel, val);
	case hwmon_temp_offset:
	val = clamp_val(val, -14875, 17000) + 14875;
	val = DIV_ROUND_CLOSEST(val, 125);
	err = max31730_set_offset_enable(data, channel,
	val != MAX31730_TEMP_OFFSET_BASELINE);
	if (err)
	return err;
	return i2c_smbus_write_byte_data(data->client,
	MAX31730_REG_TEMP_OFFSET, val);
	default:
	return -EINVAL;
	}

	val = clamp_val(val, MAX31730_TEMP_MIN, MAX31730_TEMP_MAX);
	val = DIV_ROUND_CLOSEST(val << 4, 1000) << 4;

	return i2c_smbus_write_word_swapped(data->client, reg, (u16)val);
	}

	static umode_t max31730_is_visible(const void *data,
	enum hwmon_sensor_types type,
	u32 attr, int channel)
	{
	switch (type) {
	case hwmon_temp:
	switch (attr) {
	case hwmon_temp_input:
	case hwmon_temp_min_alarm:
	case hwmon_temp_max_alarm:
	case hwmon_temp_fault:
	return 0444;
	case hwmon_temp_min:
	return channel ? 0444 : 0644;
	case hwmon_temp_offset:
	case hwmon_temp_enable:
	case hwmon_temp_max:
	return 0644;
	}
	break;
	default:
	break;
	}
	return 0;
	}

	static const struct hwmon_channel_info *max31730_info[] = {
	HWMON_CHANNEL_INFO(chip,
	HWMON_C_REGISTER_TZ),
	HWMON_CHANNEL_INFO(temp,
	HWMON_T_INPUT \| HWMON_T_MIN \| HWMON_T_MAX \|
	HWMON_T_ENABLE \|
	HWMON_T_MIN_ALARM \| HWMON_T_MAX_ALARM,
	HWMON_T_INPUT \| HWMON_T_MIN \| HWMON_T_MAX \|
	HWMON_T_OFFSET \| HWMON_T_ENABLE \|
	HWMON_T_MIN_ALARM \| HWMON_T_MAX_ALARM \|
	HWMON_T_FAULT,
	HWMON_T_INPUT \| HWMON_T_MIN \| HWMON_T_MAX \|
	HWMON_T_OFFSET \| HWMON_T_ENABLE \|
	HWMON_T_MIN_ALARM \| HWMON_T_MAX_ALARM \|
	HWMON_T_FAULT,
	HWMON_T_INPUT \| HWMON_T_MIN \| HWMON_T_MAX \|
	HWMON_T_OFFSET \| HWMON_T_ENABLE \|
	HWMON_T_MIN_ALARM \| HWMON_T_MAX_ALARM \|
	HWMON_T_FAULT
	),
	NULL
	};

	static const struct hwmon_ops max31730_hwmon_ops = {
	.is_visible = max31730_is_visible,
	.read = max31730_read,
	.write = max31730_write,
	};

	static const struct hwmon_chip_info max31730_chip_info = {
	.ops = &max31730_hwmon_ops,
	.info = max31730_info,
	};

	static void max31730_remove(void *data)
	{
	struct max31730_data *max31730 = data;
	struct i2c_client *client = max31730->client;

	i2c_smbus_write_byte_data(client, MAX31730_REG_CONF,
	max31730->orig_conf);
	}

	static int
	max31730_probe(struct i2c_client client, const struct i2c_device_id id)
	{
	struct device *dev = &client->dev;
	struct device *hwmon_dev;
	struct max31730_data *data;
	int status, err;

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

	data = devm_kzalloc(dev, sizeof(struct max31730_data), GFP_KERNEL);
	if (!data)
	return -ENOMEM;

	data->client = client;

	/* Cache original configuration and enable status */
	status = i2c_smbus_read_byte_data(client, MAX31730_REG_CHANNEL_ENABLE);
	if (status < 0)
	return status;
	data->channel_enable = status;

	status = i2c_smbus_read_byte_data(client, MAX31730_REG_OFFSET_ENABLE);
	if (status < 0)
	return status;
	data->offset_enable = status;

	status = i2c_smbus_read_byte_data(client, MAX31730_REG_CONF);
	if (status < 0)
	return status;
	data->orig_conf = status;
	data->current_conf = status;

	err = max31730_write_config(data,
	data->channel_enable ? 0 : MAX31730_STOP,
	data->channel_enable ? MAX31730_STOP : 0);
	if (err)
	return err;

	dev_set_drvdata(dev, data);

	err = devm_add_action_or_reset(dev, max31730_remove, data);
	if (err)
	return err;

	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
	data,
	&max31730_chip_info,
	NULL);
	return PTR_ERR_OR_ZERO(hwmon_dev);
	}

	static const struct i2c_device_id max31730_ids[] = {
	{ "max31730", 0, },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, max31730_ids);

	static const struct of_device_id __maybe_unused max31730_of_match[] = {
	{
	.compatible = "maxim,max31730",
	},
	{ },
	};
	MODULE_DEVICE_TABLE(of, max31730_of_match);

	static bool max31730_check_reg_temp(struct i2c_client *client,
	int reg)
	{
	int regval;

	regval = i2c_smbus_read_byte_data(client, reg + 1);
	return regval < 0 \|\| (regval & 0x0f);
	}

	/* Return 0 if detection is successful, -ENODEV otherwise */
	static int max31730_detect(struct i2c_client *client,
	struct i2c_board_info *info)
	{
	struct i2c_adapter *adapter = client->adapter;
	int regval;
	int i;

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

	regval = i2c_smbus_read_byte_data(client, MAX31730_REG_MFG_ID);
	if (regval != MAX31730_MFG_ID)
	return -ENODEV;
	regval = i2c_smbus_read_byte_data(client, MAX31730_REG_MFG_REV);
	if (regval != MAX31730_MFG_REV)
	return -ENODEV;

	/* lower 4 bit of temperature and limit registers must be 0 */
	if (max31730_check_reg_temp(client, MAX31730_REG_TEMP_MIN))
	return -ENODEV;

	for (i = 0; i < 4; i++) {
	if (max31730_check_reg_temp(client, MAX31730_REG_TEMP + i * 2))
	return -ENODEV;
	if (max31730_check_reg_temp(client,
	MAX31730_REG_TEMP_MAX + i * 2))
	return -ENODEV;
	}

	strlcpy(info->type, "max31730", I2C_NAME_SIZE);

	return 0;
	}

	static int __maybe_unused max31730_suspend(struct device *dev)
	{
	struct max31730_data *data = dev_get_drvdata(dev);

	return max31730_write_config(data, MAX31730_STOP, 0);
	}

	static int __maybe_unused max31730_resume(struct device *dev)
	{
	struct max31730_data *data = dev_get_drvdata(dev);

	return max31730_write_config(data, 0, MAX31730_STOP);
	}

	static SIMPLE_DEV_PM_OPS(max31730_pm_ops, max31730_suspend, max31730_resume);

	static struct i2c_driver max31730_driver = {
	.class = I2C_CLASS_HWMON,
	.driver = {
	.name = "max31730",
	.of_match_table = of_match_ptr(max31730_of_match),
	.pm = &max31730_pm_ops,
	},
	.probe = max31730_probe,
	.id_table = max31730_ids,
	.detect = max31730_detect,
	.address_list = normal_i2c,
	};

	module_i2c_driver(max31730_driver);

	MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
	MODULE_DESCRIPTION("MAX31730 driver");
	MODULE_LICENSE("GPL");