drivers/hwmon/lm77.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * lm77.c - Part of lm_sensors, Linux kernel modules for hardware
  *	    monitoring
  *
  * Copyright (c) 2004  Andras BALI <drewie@freemail.hu>
  *
  * Heavily based on lm75.c by Frodo Looijaard <frodol@dds.nl>.  The LM77
  * is a temperature sensor and thermal window comparator with 0.5 deg
  * resolution made by National Semiconductor.  Complete datasheet can be
  * obtained at their site:
  *	http://www.national.com/pf/LM/LM77.html
  */

 #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>

 /* Addresses to scan */
 static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
 						I2C_CLIENT_END };

 /* The LM77 registers */
 #define LM77_REG_TEMP		0x00
 #define LM77_REG_CONF		0x01
 #define LM77_REG_TEMP_HYST	0x02
 #define LM77_REG_TEMP_CRIT	0x03
 #define LM77_REG_TEMP_MIN	0x04
 #define LM77_REG_TEMP_MAX	0x05

 enum temp_index {
 	t_input = 0,
 	t_crit,
 	t_min,
 	t_max,
 	t_hyst,
 	t_num_temp
 };

 static const u8 temp_regs[t_num_temp] = {
 	[t_input] = LM77_REG_TEMP,
 	[t_min] = LM77_REG_TEMP_MIN,
 	[t_max] = LM77_REG_TEMP_MAX,
 	[t_crit] = LM77_REG_TEMP_CRIT,
 	[t_hyst] = LM77_REG_TEMP_HYST,
 };

 /* Each client has this additional data */
 struct lm77_data {
 	struct i2c_client	*client;
 	struct mutex		update_lock;
 	bool			valid;
 	unsigned long		last_updated;	/* In jiffies */
 	int			temp[t_num_temp]; /* index using temp_index */
 	u8			alarms;
 };

 /* straight from the datasheet */
 #define LM77_TEMP_MIN (-55000)
 #define LM77_TEMP_MAX 125000

 /*
  * In the temperature registers, the low 3 bits are not part of the
  * temperature values; they are the status bits.
  */
 static inline s16 LM77_TEMP_TO_REG(int temp)
 {
 	return (temp / 500) * 8;
 }

 static inline int LM77_TEMP_FROM_REG(s16 reg)
 {
 	return (reg / 8) * 500;
 }

 /*
  * All registers are word-sized, except for the configuration register.
  * The LM77 uses the high-byte first convention.
  */
 static u16 lm77_read_value(struct i2c_client *client, u8 reg)
 {
 	if (reg == LM77_REG_CONF)
 		return i2c_smbus_read_byte_data(client, reg);
 	else
 		return i2c_smbus_read_word_swapped(client, reg);
 }

 static int lm77_write_value(struct i2c_client *client, u8 reg, u16 value)
 {
 	if (reg == LM77_REG_CONF)
 		return i2c_smbus_write_byte_data(client, reg, value);
 	else
 		return i2c_smbus_write_word_swapped(client, reg, value);
 }

 static struct lm77_data *lm77_update_device(struct device *dev)
 {
 	struct lm77_data *data = dev_get_drvdata(dev);
 	struct i2c_client *client = data->client;
 	int i;

 	mutex_lock(&data->update_lock);

 	if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
 	    || !data->valid) {
 		dev_dbg(&client->dev, "Starting lm77 update\n");
 		for (i = 0; i < t_num_temp; i++) {
 			data->temp[i] =
 			  LM77_TEMP_FROM_REG(lm77_read_value(client,
 							     temp_regs[i]));
 		}
 		data->alarms =
 			lm77_read_value(client, LM77_REG_TEMP) & 0x0007;
 		data->last_updated = jiffies;
 		data->valid = true;
 	}

 	mutex_unlock(&data->update_lock);

 	return data;
 }

 /* sysfs stuff */

 static ssize_t temp_show(struct device *dev, struct device_attribute *devattr,
 			 char *buf)
 {
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 	struct lm77_data *data = lm77_update_device(dev);

 	return sprintf(buf, "%d\n", data->temp[attr->index]);
 }

 static ssize_t temp_hyst_show(struct device *dev,
 			      struct device_attribute *devattr, char *buf)
 {
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 	struct lm77_data *data = lm77_update_device(dev);
 	int nr = attr->index;
 	int temp;

 	temp = nr == t_min ? data->temp[nr] + data->temp[t_hyst] :
 			     data->temp[nr] - data->temp[t_hyst];

 	return sprintf(buf, "%d\n", temp);
 }

 static ssize_t temp_store(struct device *dev,
 			  struct device_attribute *devattr, const char *buf,
 			  size_t count)
 {
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 	struct lm77_data *data = dev_get_drvdata(dev);
 	struct i2c_client *client = data->client;
 	int nr = attr->index;
 	long val;
 	int err;

 	err = kstrtol(buf, 10, &val);
 	if (err)
 		return err;

 	val = clamp_val(val, LM77_TEMP_MIN, LM77_TEMP_MAX);
 	mutex_lock(&data->update_lock);
 	data->temp[nr] = val;
 	lm77_write_value(client, temp_regs[nr], LM77_TEMP_TO_REG(val));
 	mutex_unlock(&data->update_lock);
 	return count;
 }

 /*
  * hysteresis is stored as a relative value on the chip, so it has to be
  * converted first.
  */
 static ssize_t temp_hyst_store(struct device *dev,
 			       struct device_attribute *devattr,
 			       const char *buf, size_t count)
 {
 	struct lm77_data *data = dev_get_drvdata(dev);
 	struct i2c_client *client = data->client;
 	long val;
 	int err;

 	err = kstrtol(buf, 10, &val);
 	if (err)
 		return err;

 	mutex_lock(&data->update_lock);
 	val = clamp_val(data->temp[t_crit] - val, LM77_TEMP_MIN, LM77_TEMP_MAX);
 	data->temp[t_hyst] = val;
 	lm77_write_value(client, LM77_REG_TEMP_HYST,
 			 LM77_TEMP_TO_REG(data->temp[t_hyst]));
 	mutex_unlock(&data->update_lock);
 	return count;
 }

 static ssize_t alarm_show(struct device *dev, struct device_attribute *attr,
 			  char *buf)
 {
 	int bitnr = to_sensor_dev_attr(attr)->index;
 	struct lm77_data *data = lm77_update_device(dev);
 	return sprintf(buf, "%u\n", (data->alarms >> bitnr) & 1);
 }

 static SENSOR_DEVICE_ATTR_RO(temp1_input, temp, t_input);
 static SENSOR_DEVICE_ATTR_RW(temp1_crit, temp, t_crit);
 static SENSOR_DEVICE_ATTR_RW(temp1_min, temp, t_min);
 static SENSOR_DEVICE_ATTR_RW(temp1_max, temp, t_max);

 static SENSOR_DEVICE_ATTR_RW(temp1_crit_hyst, temp_hyst, t_crit);
 static SENSOR_DEVICE_ATTR_RO(temp1_min_hyst, temp_hyst, t_min);
 static SENSOR_DEVICE_ATTR_RO(temp1_max_hyst, temp_hyst, t_max);

 static SENSOR_DEVICE_ATTR_RO(temp1_crit_alarm, alarm, 2);
 static SENSOR_DEVICE_ATTR_RO(temp1_min_alarm, alarm, 0);
 static SENSOR_DEVICE_ATTR_RO(temp1_max_alarm, alarm, 1);

 static struct attribute *lm77_attrs[] = {
 	&sensor_dev_attr_temp1_input.dev_attr.attr,
 	&sensor_dev_attr_temp1_crit.dev_attr.attr,
 	&sensor_dev_attr_temp1_min.dev_attr.attr,
 	&sensor_dev_attr_temp1_max.dev_attr.attr,
 	&sensor_dev_attr_temp1_crit_hyst.dev_attr.attr,
 	&sensor_dev_attr_temp1_min_hyst.dev_attr.attr,
 	&sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
 	&sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
 	&sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
 	&sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
 	NULL
 };
 ATTRIBUTE_GROUPS(lm77);

 /* Return 0 if detection is successful, -ENODEV otherwise */
 static int lm77_detect(struct i2c_client *client, struct i2c_board_info *info)
 {
 	struct i2c_adapter *adapter = client->adapter;
 	int i, cur, conf, hyst, crit, min, max;

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

 	/*
 	 * Here comes the remaining detection.  Since the LM77 has no
 	 * register dedicated to identification, we have to rely on the
 	 * following tricks:
 	 *
 	 * 1. the high 4 bits represent the sign and thus they should
 	 *    always be the same
 	 * 2. the high 3 bits are unused in the configuration register
 	 * 3. addresses 0x06 and 0x07 return the last read value
 	 * 4. registers cycling over 8-address boundaries
 	 *
 	 * Word-sized registers are high-byte first.
 	 */

 	/* addresses cycling */
 	cur = i2c_smbus_read_word_data(client, 0);
 	conf = i2c_smbus_read_byte_data(client, 1);
 	hyst = i2c_smbus_read_word_data(client, 2);
 	crit = i2c_smbus_read_word_data(client, 3);
 	min = i2c_smbus_read_word_data(client, 4);
 	max = i2c_smbus_read_word_data(client, 5);
 	for (i = 8; i <= 0xff; i += 8) {
 		if (i2c_smbus_read_byte_data(client, i + 1) != conf
 		 || i2c_smbus_read_word_data(client, i + 2) != hyst
 		 || i2c_smbus_read_word_data(client, i + 3) != crit
 		 || i2c_smbus_read_word_data(client, i + 4) != min
 		 || i2c_smbus_read_word_data(client, i + 5) != max)
 			return -ENODEV;
 	}

 	/* sign bits */
 	if (((cur & 0x00f0) != 0xf0 && (cur & 0x00f0) != 0x0)
 	 || ((hyst & 0x00f0) != 0xf0 && (hyst & 0x00f0) != 0x0)
 	 || ((crit & 0x00f0) != 0xf0 && (crit & 0x00f0) != 0x0)
 	 || ((min & 0x00f0) != 0xf0 && (min & 0x00f0) != 0x0)
 	 || ((max & 0x00f0) != 0xf0 && (max & 0x00f0) != 0x0))
 		return -ENODEV;

 	/* unused bits */
 	if (conf & 0xe0)
 		return -ENODEV;

 	/* 0x06 and 0x07 return the last read value */
 	cur = i2c_smbus_read_word_data(client, 0);
 	if (i2c_smbus_read_word_data(client, 6) != cur
 	 || i2c_smbus_read_word_data(client, 7) != cur)
 		return -ENODEV;
 	hyst = i2c_smbus_read_word_data(client, 2);
 	if (i2c_smbus_read_word_data(client, 6) != hyst
 	 || i2c_smbus_read_word_data(client, 7) != hyst)
 		return -ENODEV;
 	min = i2c_smbus_read_word_data(client, 4);
 	if (i2c_smbus_read_word_data(client, 6) != min
 	 || i2c_smbus_read_word_data(client, 7) != min)
 		return -ENODEV;

 	strscpy(info->type, "lm77", I2C_NAME_SIZE);

 	return 0;
 }

 static void lm77_init_client(struct i2c_client *client)
 {
 	/* Initialize the LM77 chip - turn off shutdown mode */
 	int conf = lm77_read_value(client, LM77_REG_CONF);
 	if (conf & 1)
 		lm77_write_value(client, LM77_REG_CONF, conf & 0xfe);
 }

 static int lm77_probe(struct i2c_client *client)
 {
 	struct device *dev = &client->dev;
 	struct device *hwmon_dev;
 	struct lm77_data *data;

 	data = devm_kzalloc(dev, sizeof(struct lm77_data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;

 	data->client = client;
 	mutex_init(&data->update_lock);

 	/* Initialize the LM77 chip */
 	lm77_init_client(client);

 	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
 							   data, lm77_groups);
 	return PTR_ERR_OR_ZERO(hwmon_dev);
 }

 static const struct i2c_device_id lm77_id[] = {
 	{ "lm77" },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, lm77_id);

 /* This is the driver that will be inserted */
 static struct i2c_driver lm77_driver = {
 	.class		= I2C_CLASS_HWMON,
 	.driver = {
 		.name	= "lm77",
 	},
 	.probe		= lm77_probe,
 	.id_table	= lm77_id,
 	.detect		= lm77_detect,
 	.address_list	= normal_i2c,
 };

 module_i2c_driver(lm77_driver);

 MODULE_AUTHOR("Andras BALI <drewie@freemail.hu>");
 MODULE_DESCRIPTION("LM77 driver");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* lm77.c - Part of lm_sensors, Linux kernel modules for hardware
	* monitoring
	*
	* Copyright (c) 2004 Andras BALI <drewie@freemail.hu>
	*
	* Heavily based on lm75.c by Frodo Looijaard <frodol@dds.nl>. The LM77
	* is a temperature sensor and thermal window comparator with 0.5 deg
	* resolution made by National Semiconductor. Complete datasheet can be
	* obtained at their site:
	* http://www.national.com/pf/LM/LM77.html
	*/

	#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>

	/* Addresses to scan */
	static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
	I2C_CLIENT_END };

	/* The LM77 registers */
	#define LM77_REG_TEMP 0x00
	#define LM77_REG_CONF 0x01
	#define LM77_REG_TEMP_HYST 0x02
	#define LM77_REG_TEMP_CRIT 0x03
	#define LM77_REG_TEMP_MIN 0x04
	#define LM77_REG_TEMP_MAX 0x05

	enum temp_index {
	t_input = 0,
	t_crit,
	t_min,
	t_max,
	t_hyst,
	t_num_temp
	};

	static const u8 temp_regs[t_num_temp] = {
	[t_input] = LM77_REG_TEMP,
	[t_min] = LM77_REG_TEMP_MIN,
	[t_max] = LM77_REG_TEMP_MAX,
	[t_crit] = LM77_REG_TEMP_CRIT,
	[t_hyst] = LM77_REG_TEMP_HYST,
	};

	/* Each client has this additional data */
	struct lm77_data {
	struct i2c_client *client;
	struct mutex update_lock;
	bool valid;
	unsigned long last_updated; /* In jiffies */
	int temp[t_num_temp]; /* index using temp_index */
	u8 alarms;
	};

	/* straight from the datasheet */
	#define LM77_TEMP_MIN (-55000)
	#define LM77_TEMP_MAX 125000

	/*
	* In the temperature registers, the low 3 bits are not part of the
	* temperature values; they are the status bits.
	*/
	static inline s16 LM77_TEMP_TO_REG(int temp)
	{
	return (temp / 500) * 8;
	}

	static inline int LM77_TEMP_FROM_REG(s16 reg)
	{
	return (reg / 8) * 500;
	}

	/*
	* All registers are word-sized, except for the configuration register.
	* The LM77 uses the high-byte first convention.
	*/
	static u16 lm77_read_value(struct i2c_client *client, u8 reg)
	{
	if (reg == LM77_REG_CONF)
	return i2c_smbus_read_byte_data(client, reg);
	else
	return i2c_smbus_read_word_swapped(client, reg);
	}

	static int lm77_write_value(struct i2c_client *client, u8 reg, u16 value)
	{
	if (reg == LM77_REG_CONF)
	return i2c_smbus_write_byte_data(client, reg, value);
	else
	return i2c_smbus_write_word_swapped(client, reg, value);
	}

	static struct lm77_data lm77_update_device(struct device dev)
	{
	struct lm77_data *data = dev_get_drvdata(dev);
	struct i2c_client *client = data->client;
	int i;

	mutex_lock(&data->update_lock);

	if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
	\|\| !data->valid) {
	dev_dbg(&client->dev, "Starting lm77 update\n");
	for (i = 0; i < t_num_temp; i++) {
	data->temp[i] =
	LM77_TEMP_FROM_REG(lm77_read_value(client,
	temp_regs[i]));
	}
	data->alarms =
	lm77_read_value(client, LM77_REG_TEMP) & 0x0007;
	data->last_updated = jiffies;
	data->valid = true;
	}

	mutex_unlock(&data->update_lock);

	return data;
	}

	/* sysfs stuff */

	static ssize_t temp_show(struct device dev, struct device_attribute devattr,
	char *buf)
	{
	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
	struct lm77_data *data = lm77_update_device(dev);

	return sprintf(buf, "%d\n", data->temp[attr->index]);
	}

	static ssize_t temp_hyst_show(struct device *dev,
	struct device_attribute devattr, char buf)
	{
	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
	struct lm77_data *data = lm77_update_device(dev);
	int nr = attr->index;
	int temp;

	temp = nr == t_min ? data->temp[nr] + data->temp[t_hyst] :
	data->temp[nr] - data->temp[t_hyst];

	return sprintf(buf, "%d\n", temp);
	}

	static ssize_t temp_store(struct device *dev,
	struct device_attribute devattr, const char buf,
	size_t count)
	{
	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
	struct lm77_data *data = dev_get_drvdata(dev);
	struct i2c_client *client = data->client;
	int nr = attr->index;
	long val;
	int err;

	err = kstrtol(buf, 10, &val);
	if (err)
	return err;

	val = clamp_val(val, LM77_TEMP_MIN, LM77_TEMP_MAX);
	mutex_lock(&data->update_lock);
	data->temp[nr] = val;
	lm77_write_value(client, temp_regs[nr], LM77_TEMP_TO_REG(val));
	mutex_unlock(&data->update_lock);
	return count;
	}

	/*
	* hysteresis is stored as a relative value on the chip, so it has to be
	* converted first.
	*/
	static ssize_t temp_hyst_store(struct device *dev,
	struct device_attribute *devattr,
	const char *buf, size_t count)
	{
	struct lm77_data *data = dev_get_drvdata(dev);
	struct i2c_client *client = data->client;
	long val;
	int err;

	err = kstrtol(buf, 10, &val);
	if (err)
	return err;

	mutex_lock(&data->update_lock);
	val = clamp_val(data->temp[t_crit] - val, LM77_TEMP_MIN, LM77_TEMP_MAX);
	data->temp[t_hyst] = val;
	lm77_write_value(client, LM77_REG_TEMP_HYST,
	LM77_TEMP_TO_REG(data->temp[t_hyst]));
	mutex_unlock(&data->update_lock);
	return count;
	}

	static ssize_t alarm_show(struct device dev, struct device_attribute attr,
	char *buf)
	{
	int bitnr = to_sensor_dev_attr(attr)->index;
	struct lm77_data *data = lm77_update_device(dev);
	return sprintf(buf, "%u\n", (data->alarms >> bitnr) & 1);
	}

	static SENSOR_DEVICE_ATTR_RO(temp1_input, temp, t_input);
	static SENSOR_DEVICE_ATTR_RW(temp1_crit, temp, t_crit);
	static SENSOR_DEVICE_ATTR_RW(temp1_min, temp, t_min);
	static SENSOR_DEVICE_ATTR_RW(temp1_max, temp, t_max);

	static SENSOR_DEVICE_ATTR_RW(temp1_crit_hyst, temp_hyst, t_crit);
	static SENSOR_DEVICE_ATTR_RO(temp1_min_hyst, temp_hyst, t_min);
	static SENSOR_DEVICE_ATTR_RO(temp1_max_hyst, temp_hyst, t_max);

	static SENSOR_DEVICE_ATTR_RO(temp1_crit_alarm, alarm, 2);
	static SENSOR_DEVICE_ATTR_RO(temp1_min_alarm, alarm, 0);
	static SENSOR_DEVICE_ATTR_RO(temp1_max_alarm, alarm, 1);

	static struct attribute *lm77_attrs[] = {
	&sensor_dev_attr_temp1_input.dev_attr.attr,
	&sensor_dev_attr_temp1_crit.dev_attr.attr,
	&sensor_dev_attr_temp1_min.dev_attr.attr,
	&sensor_dev_attr_temp1_max.dev_attr.attr,
	&sensor_dev_attr_temp1_crit_hyst.dev_attr.attr,
	&sensor_dev_attr_temp1_min_hyst.dev_attr.attr,
	&sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
	&sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
	&sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
	&sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
	NULL
	};
	ATTRIBUTE_GROUPS(lm77);

	/* Return 0 if detection is successful, -ENODEV otherwise */
	static int lm77_detect(struct i2c_client client, struct i2c_board_info info)
	{
	struct i2c_adapter *adapter = client->adapter;
	int i, cur, conf, hyst, crit, min, max;

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

	/*
	* Here comes the remaining detection. Since the LM77 has no
	* register dedicated to identification, we have to rely on the
	* following tricks:
	*
	* 1. the high 4 bits represent the sign and thus they should
	* always be the same
	* 2. the high 3 bits are unused in the configuration register
	* 3. addresses 0x06 and 0x07 return the last read value
	* 4. registers cycling over 8-address boundaries
	*
	* Word-sized registers are high-byte first.
	*/

	/* addresses cycling */
	cur = i2c_smbus_read_word_data(client, 0);
	conf = i2c_smbus_read_byte_data(client, 1);
	hyst = i2c_smbus_read_word_data(client, 2);
	crit = i2c_smbus_read_word_data(client, 3);
	min = i2c_smbus_read_word_data(client, 4);
	max = i2c_smbus_read_word_data(client, 5);
	for (i = 8; i <= 0xff; i += 8) {
	if (i2c_smbus_read_byte_data(client, i + 1) != conf
	\|\| i2c_smbus_read_word_data(client, i + 2) != hyst
	\|\| i2c_smbus_read_word_data(client, i + 3) != crit
	\|\| i2c_smbus_read_word_data(client, i + 4) != min
	\|\| i2c_smbus_read_word_data(client, i + 5) != max)
	return -ENODEV;
	}

	/* sign bits */
	if (((cur & 0x00f0) != 0xf0 && (cur & 0x00f0) != 0x0)
	\|\| ((hyst & 0x00f0) != 0xf0 && (hyst & 0x00f0) != 0x0)
	\|\| ((crit & 0x00f0) != 0xf0 && (crit & 0x00f0) != 0x0)
	\|\| ((min & 0x00f0) != 0xf0 && (min & 0x00f0) != 0x0)
	\|\| ((max & 0x00f0) != 0xf0 && (max & 0x00f0) != 0x0))
	return -ENODEV;

	/* unused bits */
	if (conf & 0xe0)
	return -ENODEV;

	/* 0x06 and 0x07 return the last read value */
	cur = i2c_smbus_read_word_data(client, 0);
	if (i2c_smbus_read_word_data(client, 6) != cur
	\|\| i2c_smbus_read_word_data(client, 7) != cur)
	return -ENODEV;
	hyst = i2c_smbus_read_word_data(client, 2);
	if (i2c_smbus_read_word_data(client, 6) != hyst
	\|\| i2c_smbus_read_word_data(client, 7) != hyst)
	return -ENODEV;
	min = i2c_smbus_read_word_data(client, 4);
	if (i2c_smbus_read_word_data(client, 6) != min
	\|\| i2c_smbus_read_word_data(client, 7) != min)
	return -ENODEV;

	strscpy(info->type, "lm77", I2C_NAME_SIZE);

	return 0;
	}

	static void lm77_init_client(struct i2c_client *client)
	{
	/* Initialize the LM77 chip - turn off shutdown mode */
	int conf = lm77_read_value(client, LM77_REG_CONF);
	if (conf & 1)
	lm77_write_value(client, LM77_REG_CONF, conf & 0xfe);
	}

	static int lm77_probe(struct i2c_client *client)
	{
	struct device *dev = &client->dev;
	struct device *hwmon_dev;
	struct lm77_data *data;

	data = devm_kzalloc(dev, sizeof(struct lm77_data), GFP_KERNEL);
	if (!data)
	return -ENOMEM;

	data->client = client;
	mutex_init(&data->update_lock);

	/* Initialize the LM77 chip */
	lm77_init_client(client);

	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
	data, lm77_groups);
	return PTR_ERR_OR_ZERO(hwmon_dev);
	}

	static const struct i2c_device_id lm77_id[] = {
	{ "lm77" },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, lm77_id);

	/* This is the driver that will be inserted */
	static struct i2c_driver lm77_driver = {
	.class = I2C_CLASS_HWMON,
	.driver = {
	.name = "lm77",
	},
	.probe = lm77_probe,
	.id_table = lm77_id,
	.detect = lm77_detect,
	.address_list = normal_i2c,
	};

	module_i2c_driver(lm77_driver);

	MODULE_AUTHOR("Andras BALI <drewie@freemail.hu>");
	MODULE_DESCRIPTION("LM77 driver");
	MODULE_LICENSE("GPL");