drivers/hwmon/lm92.c - kernel/msm-4.9 - Gitiles

 /*
  * lm92 - Hardware monitoring driver
  * Copyright (C) 2005-2008  Jean Delvare <jdelvare@suse.de>
  *
  * Based on the lm90 driver, with some ideas taken from the lm_sensors
  * lm92 driver as well.
  *
  * The LM92 is a sensor chip made by National Semiconductor. It reports
  * its own temperature with a 0.0625 deg resolution and a 0.33 deg
  * accuracy. Complete datasheet can be obtained from National's website
  * at:
  *   http://www.national.com/pf/LM/LM92.html
  *
  * This driver also supports the MAX6635 sensor chip made by Maxim.
  * This chip is compatible with the LM92, but has a lesser accuracy
  * (1.0 deg). Complete datasheet can be obtained from Maxim's website
  * at:
  *   http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3074
  *
  * Since the LM92 was the first chipset supported by this driver, most
  * comments will refer to this chipset, but are actually general and
  * concern all supported chipsets, unless mentioned otherwise.
  *
  * Support could easily be added for the National Semiconductor LM76
  * and Maxim MAX6633 and MAX6634 chips, which are mostly compatible
  * with the LM92.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */

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

 /*
  * The LM92 and MAX6635 have 2 two-state pins for address selection,
  * resulting in 4 possible addresses.
  */
 static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
 						I2C_CLIENT_END };

 /* The LM92 registers */
 #define LM92_REG_CONFIG			0x01 /* 8-bit, RW */
 #define LM92_REG_TEMP			0x00 /* 16-bit, RO */
 #define LM92_REG_TEMP_HYST		0x02 /* 16-bit, RW */
 #define LM92_REG_TEMP_CRIT		0x03 /* 16-bit, RW */
 #define LM92_REG_TEMP_LOW		0x04 /* 16-bit, RW */
 #define LM92_REG_TEMP_HIGH		0x05 /* 16-bit, RW */
 #define LM92_REG_MAN_ID			0x07 /* 16-bit, RO, LM92 only */

 /*
  * The LM92 uses signed 13-bit values with LSB = 0.0625 degree Celsius,
  * left-justified in 16-bit registers. No rounding is done, with such
  * a resolution it's just not worth it. Note that the MAX6635 doesn't
  * make use of the 4 lower bits for limits (i.e. effective resolution
  * for limits is 1 degree Celsius).
  */
 static inline int TEMP_FROM_REG(s16 reg)
 {
 	return reg / 8 * 625 / 10;
 }

 static inline s16 TEMP_TO_REG(int val)
 {
 	if (val <= -60000)
 		return -60000 * 10 / 625 * 8;
 	if (val >= 160000)
 		return 160000 * 10 / 625 * 8;
 	return val * 10 / 625 * 8;
 }

 /* Alarm flags are stored in the 3 LSB of the temperature register */
 static inline u8 ALARMS_FROM_REG(s16 reg)
 {
 	return reg & 0x0007;
 }

 /* Driver data (common to all clients) */
 static struct i2c_driver lm92_driver;

 /* Client data (each client gets its own) */
 struct lm92_data {
 	struct device *hwmon_dev;
 	struct mutex update_lock;
 	char valid; /* zero until following fields are valid */
 	unsigned long last_updated; /* in jiffies */

 	/* registers values */
 	s16 temp1_input, temp1_crit, temp1_min, temp1_max, temp1_hyst;
 };


 /*
  * Sysfs attributes and callback functions
  */

 static struct lm92_data *lm92_update_device(struct device *dev)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct lm92_data *data = i2c_get_clientdata(client);

 	mutex_lock(&data->update_lock);

 	if (time_after(jiffies, data->last_updated + HZ)
 	 || !data->valid) {
 		dev_dbg(&client->dev, "Updating lm92 data\n");
 		data->temp1_input = i2c_smbus_read_word_swapped(client,
 				    LM92_REG_TEMP);
 		data->temp1_hyst = i2c_smbus_read_word_swapped(client,
 				    LM92_REG_TEMP_HYST);
 		data->temp1_crit = i2c_smbus_read_word_swapped(client,
 				    LM92_REG_TEMP_CRIT);
 		data->temp1_min = i2c_smbus_read_word_swapped(client,
 				    LM92_REG_TEMP_LOW);
 		data->temp1_max = i2c_smbus_read_word_swapped(client,
 				    LM92_REG_TEMP_HIGH);

 		data->last_updated = jiffies;
 		data->valid = 1;
 	}

 	mutex_unlock(&data->update_lock);

 	return data;
 }

 #define show_temp(value) \
 static ssize_t show_##value(struct device *dev, struct device_attribute *attr, \
 			    char *buf) \
 { \
 	struct lm92_data *data = lm92_update_device(dev); \
 	return sprintf(buf, "%d\n", TEMP_FROM_REG(data->value)); \
 }
 show_temp(temp1_input);
 show_temp(temp1_crit);
 show_temp(temp1_min);
 show_temp(temp1_max);

 #define set_temp(value, reg) \
 static ssize_t set_##value(struct device *dev, struct device_attribute *attr, \
 			   const char *buf, \
 	size_t count) \
 { \
 	struct i2c_client *client = to_i2c_client(dev); \
 	struct lm92_data *data = i2c_get_clientdata(client); \
 	long val; \
 	int err = kstrtol(buf, 10, &val); \
 	if (err) \
 		return err; \
 \
 	mutex_lock(&data->update_lock); \
 	data->value = TEMP_TO_REG(val); \
 	i2c_smbus_write_word_swapped(client, reg, data->value); \
 	mutex_unlock(&data->update_lock); \
 	return count; \
 }
 set_temp(temp1_crit, LM92_REG_TEMP_CRIT);
 set_temp(temp1_min, LM92_REG_TEMP_LOW);
 set_temp(temp1_max, LM92_REG_TEMP_HIGH);

 static ssize_t show_temp1_crit_hyst(struct device *dev,
 				    struct device_attribute *attr, char *buf)
 {
 	struct lm92_data *data = lm92_update_device(dev);
 	return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp1_crit)
 		       - TEMP_FROM_REG(data->temp1_hyst));
 }
 static ssize_t show_temp1_max_hyst(struct device *dev,
 				   struct device_attribute *attr, char *buf)
 {
 	struct lm92_data *data = lm92_update_device(dev);
 	return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp1_max)
 		       - TEMP_FROM_REG(data->temp1_hyst));
 }
 static ssize_t show_temp1_min_hyst(struct device *dev,
 				   struct device_attribute *attr, char *buf)
 {
 	struct lm92_data *data = lm92_update_device(dev);
 	return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp1_min)
 		       + TEMP_FROM_REG(data->temp1_hyst));
 }

 static ssize_t set_temp1_crit_hyst(struct device *dev,
 				   struct device_attribute *attr,
 				   const char *buf, size_t count)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct lm92_data *data = i2c_get_clientdata(client);
 	long val;
 	int err;

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

 	mutex_lock(&data->update_lock);
 	data->temp1_hyst = TEMP_FROM_REG(data->temp1_crit) - val;
 	i2c_smbus_write_word_swapped(client, LM92_REG_TEMP_HYST,
 				     TEMP_TO_REG(data->temp1_hyst));
 	mutex_unlock(&data->update_lock);
 	return count;
 }

 static ssize_t show_alarms(struct device *dev, struct device_attribute *attr,
 			   char *buf)
 {
 	struct lm92_data *data = lm92_update_device(dev);
 	return sprintf(buf, "%d\n", ALARMS_FROM_REG(data->temp1_input));
 }

 static ssize_t show_alarm(struct device *dev, struct device_attribute *attr,
 			  char *buf)
 {
 	int bitnr = to_sensor_dev_attr(attr)->index;
 	struct lm92_data *data = lm92_update_device(dev);
 	return sprintf(buf, "%d\n", (data->temp1_input >> bitnr) & 1);
 }

 static DEVICE_ATTR(temp1_input, S_IRUGO, show_temp1_input, NULL);
 static DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO, show_temp1_crit,
 	set_temp1_crit);
 static DEVICE_ATTR(temp1_crit_hyst, S_IWUSR | S_IRUGO, show_temp1_crit_hyst,
 	set_temp1_crit_hyst);
 static DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO, show_temp1_min,
 	set_temp1_min);
 static DEVICE_ATTR(temp1_min_hyst, S_IRUGO, show_temp1_min_hyst, NULL);
 static DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp1_max,
 	set_temp1_max);
 static DEVICE_ATTR(temp1_max_hyst, S_IRUGO, show_temp1_max_hyst, NULL);
 static DEVICE_ATTR(alarms, S_IRUGO, show_alarms, NULL);
 static SENSOR_DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL, 2);
 static SENSOR_DEVICE_ATTR(temp1_min_alarm, S_IRUGO, show_alarm, NULL, 0);
 static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL, 1);


 /*
  * Detection and registration
  */

 static void lm92_init_client(struct i2c_client *client)
 {
 	u8 config;

 	/* Start the conversions if needed */
 	config = i2c_smbus_read_byte_data(client, LM92_REG_CONFIG);
 	if (config & 0x01)
 		i2c_smbus_write_byte_data(client, LM92_REG_CONFIG,
 					  config & 0xFE);
 }

 /*
  * The MAX6635 has no identification register, so we have to use tricks
  * to identify it reliably. This is somewhat slow.
  * Note that we do NOT rely on the 2 MSB of the configuration register
  * always reading 0, as suggested by the datasheet, because it was once
  * reported not to be true.
  */
 static int max6635_check(struct i2c_client *client)
 {
 	u16 temp_low, temp_high, temp_hyst, temp_crit;
 	u8 conf;
 	int i;

 	/*
 	 * No manufacturer ID register, so a read from this address will
 	 * always return the last read value.
 	 */
 	temp_low = i2c_smbus_read_word_data(client, LM92_REG_TEMP_LOW);
 	if (i2c_smbus_read_word_data(client, LM92_REG_MAN_ID) != temp_low)
 		return 0;
 	temp_high = i2c_smbus_read_word_data(client, LM92_REG_TEMP_HIGH);
 	if (i2c_smbus_read_word_data(client, LM92_REG_MAN_ID) != temp_high)
 		return 0;

 	/* Limits are stored as integer values (signed, 9-bit). */
 	if ((temp_low & 0x7f00) || (temp_high & 0x7f00))
 		return 0;
 	temp_hyst = i2c_smbus_read_word_data(client, LM92_REG_TEMP_HYST);
 	temp_crit = i2c_smbus_read_word_data(client, LM92_REG_TEMP_CRIT);
 	if ((temp_hyst & 0x7f00) || (temp_crit & 0x7f00))
 		return 0;

 	/*
 	 * Registers addresses were found to cycle over 16-byte boundaries.
 	 * We don't test all registers with all offsets so as to save some
 	 * reads and time, but this should still be sufficient to dismiss
 	 * non-MAX6635 chips.
 	 */
 	conf = i2c_smbus_read_byte_data(client, LM92_REG_CONFIG);
 	for (i = 16; i < 96; i *= 2) {
 		if (temp_hyst != i2c_smbus_read_word_data(client,
 				 LM92_REG_TEMP_HYST + i - 16)
 		 || temp_crit != i2c_smbus_read_word_data(client,
 				 LM92_REG_TEMP_CRIT + i)
 		 || temp_low != i2c_smbus_read_word_data(client,
 				LM92_REG_TEMP_LOW + i + 16)
 		 || temp_high != i2c_smbus_read_word_data(client,
 				 LM92_REG_TEMP_HIGH + i + 32)
 		 || conf != i2c_smbus_read_byte_data(client,
 			    LM92_REG_CONFIG + i))
 			return 0;
 	}

 	return 1;
 }

 static struct attribute *lm92_attributes[] = {
 	&dev_attr_temp1_input.attr,
 	&dev_attr_temp1_crit.attr,
 	&dev_attr_temp1_crit_hyst.attr,
 	&dev_attr_temp1_min.attr,
 	&dev_attr_temp1_min_hyst.attr,
 	&dev_attr_temp1_max.attr,
 	&dev_attr_temp1_max_hyst.attr,
 	&dev_attr_alarms.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
 };

 static const struct attribute_group lm92_group = {
 	.attrs = lm92_attributes,
 };

 /* Return 0 if detection is successful, -ENODEV otherwise */
 static int lm92_detect(struct i2c_client *new_client,
 		       struct i2c_board_info *info)
 {
 	struct i2c_adapter *adapter = new_client->adapter;
 	u8 config;
 	u16 man_id;

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

 	config = i2c_smbus_read_byte_data(new_client, LM92_REG_CONFIG);
 	man_id = i2c_smbus_read_word_data(new_client, LM92_REG_MAN_ID);

 	if ((config & 0xe0) == 0x00 && man_id == 0x0180)
 		pr_info("lm92: Found National Semiconductor LM92 chip\n");
 	else if (max6635_check(new_client))
 		pr_info("lm92: Found Maxim MAX6635 chip\n");
 	else
 		return -ENODEV;

 	strlcpy(info->type, "lm92", I2C_NAME_SIZE);

 	return 0;
 }

 static int lm92_probe(struct i2c_client *new_client,
 		      const struct i2c_device_id *id)
 {
 	struct lm92_data *data;
 	int err;

 	data = devm_kzalloc(&new_client->dev, sizeof(struct lm92_data),
 			    GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;

 	i2c_set_clientdata(new_client, data);
 	mutex_init(&data->update_lock);

 	/* Initialize the chipset */
 	lm92_init_client(new_client);

 	/* Register sysfs hooks */
 	err = sysfs_create_group(&new_client->dev.kobj, &lm92_group);
 	if (err)
 		return err;

 	data->hwmon_dev = hwmon_device_register(&new_client->dev);
 	if (IS_ERR(data->hwmon_dev)) {
 		err = PTR_ERR(data->hwmon_dev);
 		goto exit_remove;
 	}

 	return 0;

 exit_remove:
 	sysfs_remove_group(&new_client->dev.kobj, &lm92_group);
 	return err;
 }

 static int lm92_remove(struct i2c_client *client)
 {
 	struct lm92_data *data = i2c_get_clientdata(client);

 	hwmon_device_unregister(data->hwmon_dev);
 	sysfs_remove_group(&client->dev.kobj, &lm92_group);

 	return 0;
 }


 /*
  * Module and driver stuff
  */

 static const struct i2c_device_id lm92_id[] = {
 	{ "lm92", 0 },
 	/* max6635 could be added here */
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, lm92_id);

 static struct i2c_driver lm92_driver = {
 	.class		= I2C_CLASS_HWMON,
 	.driver = {
 		.name	= "lm92",
 	},
 	.probe		= lm92_probe,
 	.remove		= lm92_remove,
 	.id_table	= lm92_id,
 	.detect		= lm92_detect,
 	.address_list	= normal_i2c,
 };

 module_i2c_driver(lm92_driver);

 MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
 MODULE_DESCRIPTION("LM92/MAX6635 driver");
 MODULE_LICENSE("GPL");
	/*
	* lm92 - Hardware monitoring driver
	* Copyright (C) 2005-2008 Jean Delvare <jdelvare@suse.de>
	*
	* Based on the lm90 driver, with some ideas taken from the lm_sensors
	* lm92 driver as well.
	*
	* The LM92 is a sensor chip made by National Semiconductor. It reports
	* its own temperature with a 0.0625 deg resolution and a 0.33 deg
	* accuracy. Complete datasheet can be obtained from National's website
	* at:
	* http://www.national.com/pf/LM/LM92.html
	*
	* This driver also supports the MAX6635 sensor chip made by Maxim.
	* This chip is compatible with the LM92, but has a lesser accuracy
	* (1.0 deg). Complete datasheet can be obtained from Maxim's website
	* at:
	* http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3074
	*
	* Since the LM92 was the first chipset supported by this driver, most
	* comments will refer to this chipset, but are actually general and
	* concern all supported chipsets, unless mentioned otherwise.
	*
	* Support could easily be added for the National Semiconductor LM76
	* and Maxim MAX6633 and MAX6634 chips, which are mostly compatible
	* with the LM92.
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
	*/

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

	/*
	* The LM92 and MAX6635 have 2 two-state pins for address selection,
	* resulting in 4 possible addresses.
	*/
	static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
	I2C_CLIENT_END };

	/* The LM92 registers */
	#define LM92_REG_CONFIG 0x01 /* 8-bit, RW */
	#define LM92_REG_TEMP 0x00 /* 16-bit, RO */
	#define LM92_REG_TEMP_HYST 0x02 /* 16-bit, RW */
	#define LM92_REG_TEMP_CRIT 0x03 /* 16-bit, RW */
	#define LM92_REG_TEMP_LOW 0x04 /* 16-bit, RW */
	#define LM92_REG_TEMP_HIGH 0x05 /* 16-bit, RW */
	#define LM92_REG_MAN_ID 0x07 /* 16-bit, RO, LM92 only */

	/*
	* The LM92 uses signed 13-bit values with LSB = 0.0625 degree Celsius,
	* left-justified in 16-bit registers. No rounding is done, with such
	* a resolution it's just not worth it. Note that the MAX6635 doesn't
	* make use of the 4 lower bits for limits (i.e. effective resolution
	* for limits is 1 degree Celsius).
	*/
	static inline int TEMP_FROM_REG(s16 reg)
	{
	return reg / 8 * 625 / 10;
	}

	static inline s16 TEMP_TO_REG(int val)
	{
	if (val <= -60000)
	return -60000 * 10 / 625 * 8;
	if (val >= 160000)
	return 160000 * 10 / 625 * 8;
	return val * 10 / 625 * 8;
	}

	/* Alarm flags are stored in the 3 LSB of the temperature register */
	static inline u8 ALARMS_FROM_REG(s16 reg)
	{
	return reg & 0x0007;
	}

	/* Driver data (common to all clients) */
	static struct i2c_driver lm92_driver;

	/* Client data (each client gets its own) */
	struct lm92_data {
	struct device *hwmon_dev;
	struct mutex update_lock;
	char valid; /* zero until following fields are valid */
	unsigned long last_updated; /* in jiffies */

	/* registers values */
	s16 temp1_input, temp1_crit, temp1_min, temp1_max, temp1_hyst;
	};


	/*
	* Sysfs attributes and callback functions
	*/

	static struct lm92_data lm92_update_device(struct device dev)
	{
	struct i2c_client *client = to_i2c_client(dev);
	struct lm92_data *data = i2c_get_clientdata(client);

	mutex_lock(&data->update_lock);

	if (time_after(jiffies, data->last_updated + HZ)
	\|\| !data->valid) {
	dev_dbg(&client->dev, "Updating lm92 data\n");
	data->temp1_input = i2c_smbus_read_word_swapped(client,
	LM92_REG_TEMP);
	data->temp1_hyst = i2c_smbus_read_word_swapped(client,
	LM92_REG_TEMP_HYST);
	data->temp1_crit = i2c_smbus_read_word_swapped(client,
	LM92_REG_TEMP_CRIT);
	data->temp1_min = i2c_smbus_read_word_swapped(client,
	LM92_REG_TEMP_LOW);
	data->temp1_max = i2c_smbus_read_word_swapped(client,
	LM92_REG_TEMP_HIGH);

	data->last_updated = jiffies;
	data->valid = 1;
	}

	mutex_unlock(&data->update_lock);

	return data;
	}

	#define show_temp(value) \
	static ssize_t show_##value(struct device dev, struct device_attribute attr, \
	char *buf) \
	{ \
	struct lm92_data *data = lm92_update_device(dev); \
	return sprintf(buf, "%d\n", TEMP_FROM_REG(data->value)); \
	}
	show_temp(temp1_input);
	show_temp(temp1_crit);
	show_temp(temp1_min);
	show_temp(temp1_max);

	#define set_temp(value, reg) \
	static ssize_t set_##value(struct device dev, struct device_attribute attr, \
	const char *buf, \
	size_t count) \
	{ \
	struct i2c_client *client = to_i2c_client(dev); \
	struct lm92_data *data = i2c_get_clientdata(client); \
	long val; \
	int err = kstrtol(buf, 10, &val); \
	if (err) \
	return err; \
	\
	mutex_lock(&data->update_lock); \
	data->value = TEMP_TO_REG(val); \
	i2c_smbus_write_word_swapped(client, reg, data->value); \
	mutex_unlock(&data->update_lock); \
	return count; \
	}
	set_temp(temp1_crit, LM92_REG_TEMP_CRIT);
	set_temp(temp1_min, LM92_REG_TEMP_LOW);
	set_temp(temp1_max, LM92_REG_TEMP_HIGH);

	static ssize_t show_temp1_crit_hyst(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct lm92_data *data = lm92_update_device(dev);
	return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp1_crit)
	- TEMP_FROM_REG(data->temp1_hyst));
	}
	static ssize_t show_temp1_max_hyst(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct lm92_data *data = lm92_update_device(dev);
	return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp1_max)
	- TEMP_FROM_REG(data->temp1_hyst));
	}
	static ssize_t show_temp1_min_hyst(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct lm92_data *data = lm92_update_device(dev);
	return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp1_min)
	+ TEMP_FROM_REG(data->temp1_hyst));
	}

	static ssize_t set_temp1_crit_hyst(struct device *dev,
	struct device_attribute *attr,
	const char *buf, size_t count)
	{
	struct i2c_client *client = to_i2c_client(dev);
	struct lm92_data *data = i2c_get_clientdata(client);
	long val;
	int err;

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

	mutex_lock(&data->update_lock);
	data->temp1_hyst = TEMP_FROM_REG(data->temp1_crit) - val;
	i2c_smbus_write_word_swapped(client, LM92_REG_TEMP_HYST,
	TEMP_TO_REG(data->temp1_hyst));
	mutex_unlock(&data->update_lock);
	return count;
	}

	static ssize_t show_alarms(struct device dev, struct device_attribute attr,
	char *buf)
	{
	struct lm92_data *data = lm92_update_device(dev);
	return sprintf(buf, "%d\n", ALARMS_FROM_REG(data->temp1_input));
	}

	static ssize_t show_alarm(struct device dev, struct device_attribute attr,
	char *buf)
	{
	int bitnr = to_sensor_dev_attr(attr)->index;
	struct lm92_data *data = lm92_update_device(dev);
	return sprintf(buf, "%d\n", (data->temp1_input >> bitnr) & 1);
	}

	static DEVICE_ATTR(temp1_input, S_IRUGO, show_temp1_input, NULL);
	static DEVICE_ATTR(temp1_crit, S_IWUSR \| S_IRUGO, show_temp1_crit,
	set_temp1_crit);
	static DEVICE_ATTR(temp1_crit_hyst, S_IWUSR \| S_IRUGO, show_temp1_crit_hyst,
	set_temp1_crit_hyst);
	static DEVICE_ATTR(temp1_min, S_IWUSR \| S_IRUGO, show_temp1_min,
	set_temp1_min);
	static DEVICE_ATTR(temp1_min_hyst, S_IRUGO, show_temp1_min_hyst, NULL);
	static DEVICE_ATTR(temp1_max, S_IWUSR \| S_IRUGO, show_temp1_max,
	set_temp1_max);
	static DEVICE_ATTR(temp1_max_hyst, S_IRUGO, show_temp1_max_hyst, NULL);
	static DEVICE_ATTR(alarms, S_IRUGO, show_alarms, NULL);
	static SENSOR_DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL, 2);
	static SENSOR_DEVICE_ATTR(temp1_min_alarm, S_IRUGO, show_alarm, NULL, 0);
	static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL, 1);


	/*
	* Detection and registration
	*/

	static void lm92_init_client(struct i2c_client *client)
	{
	u8 config;

	/* Start the conversions if needed */
	config = i2c_smbus_read_byte_data(client, LM92_REG_CONFIG);
	if (config & 0x01)
	i2c_smbus_write_byte_data(client, LM92_REG_CONFIG,
	config & 0xFE);
	}

	/*
	* The MAX6635 has no identification register, so we have to use tricks
	* to identify it reliably. This is somewhat slow.
	* Note that we do NOT rely on the 2 MSB of the configuration register
	* always reading 0, as suggested by the datasheet, because it was once
	* reported not to be true.
	*/
	static int max6635_check(struct i2c_client *client)
	{
	u16 temp_low, temp_high, temp_hyst, temp_crit;
	u8 conf;
	int i;

	/*
	* No manufacturer ID register, so a read from this address will
	* always return the last read value.
	*/
	temp_low = i2c_smbus_read_word_data(client, LM92_REG_TEMP_LOW);
	if (i2c_smbus_read_word_data(client, LM92_REG_MAN_ID) != temp_low)
	return 0;
	temp_high = i2c_smbus_read_word_data(client, LM92_REG_TEMP_HIGH);
	if (i2c_smbus_read_word_data(client, LM92_REG_MAN_ID) != temp_high)
	return 0;

	/* Limits are stored as integer values (signed, 9-bit). */
	if ((temp_low & 0x7f00) \|\| (temp_high & 0x7f00))
	return 0;
	temp_hyst = i2c_smbus_read_word_data(client, LM92_REG_TEMP_HYST);
	temp_crit = i2c_smbus_read_word_data(client, LM92_REG_TEMP_CRIT);
	if ((temp_hyst & 0x7f00) \|\| (temp_crit & 0x7f00))
	return 0;

	/*
	* Registers addresses were found to cycle over 16-byte boundaries.
	* We don't test all registers with all offsets so as to save some
	* reads and time, but this should still be sufficient to dismiss
	* non-MAX6635 chips.
	*/
	conf = i2c_smbus_read_byte_data(client, LM92_REG_CONFIG);
	for (i = 16; i < 96; i *= 2) {
	if (temp_hyst != i2c_smbus_read_word_data(client,
	LM92_REG_TEMP_HYST + i - 16)
	\|\| temp_crit != i2c_smbus_read_word_data(client,
	LM92_REG_TEMP_CRIT + i)
	\|\| temp_low != i2c_smbus_read_word_data(client,
	LM92_REG_TEMP_LOW + i + 16)
	\|\| temp_high != i2c_smbus_read_word_data(client,
	LM92_REG_TEMP_HIGH + i + 32)
	\|\| conf != i2c_smbus_read_byte_data(client,
	LM92_REG_CONFIG + i))
	return 0;
	}

	return 1;
	}

	static struct attribute *lm92_attributes[] = {
	&dev_attr_temp1_input.attr,
	&dev_attr_temp1_crit.attr,
	&dev_attr_temp1_crit_hyst.attr,
	&dev_attr_temp1_min.attr,
	&dev_attr_temp1_min_hyst.attr,
	&dev_attr_temp1_max.attr,
	&dev_attr_temp1_max_hyst.attr,
	&dev_attr_alarms.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
	};

	static const struct attribute_group lm92_group = {
	.attrs = lm92_attributes,
	};

	/* Return 0 if detection is successful, -ENODEV otherwise */
	static int lm92_detect(struct i2c_client *new_client,
	struct i2c_board_info *info)
	{
	struct i2c_adapter *adapter = new_client->adapter;
	u8 config;
	u16 man_id;

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

	config = i2c_smbus_read_byte_data(new_client, LM92_REG_CONFIG);
	man_id = i2c_smbus_read_word_data(new_client, LM92_REG_MAN_ID);

	if ((config & 0xe0) == 0x00 && man_id == 0x0180)
	pr_info("lm92: Found National Semiconductor LM92 chip\n");
	else if (max6635_check(new_client))
	pr_info("lm92: Found Maxim MAX6635 chip\n");
	else
	return -ENODEV;

	strlcpy(info->type, "lm92", I2C_NAME_SIZE);

	return 0;
	}

	static int lm92_probe(struct i2c_client *new_client,
	const struct i2c_device_id *id)
	{
	struct lm92_data *data;
	int err;

	data = devm_kzalloc(&new_client->dev, sizeof(struct lm92_data),
	GFP_KERNEL);
	if (!data)
	return -ENOMEM;

	i2c_set_clientdata(new_client, data);
	mutex_init(&data->update_lock);

	/* Initialize the chipset */
	lm92_init_client(new_client);

	/* Register sysfs hooks */
	err = sysfs_create_group(&new_client->dev.kobj, &lm92_group);
	if (err)
	return err;

	data->hwmon_dev = hwmon_device_register(&new_client->dev);
	if (IS_ERR(data->hwmon_dev)) {
	err = PTR_ERR(data->hwmon_dev);
	goto exit_remove;
	}

	return 0;

	exit_remove:
	sysfs_remove_group(&new_client->dev.kobj, &lm92_group);
	return err;
	}

	static int lm92_remove(struct i2c_client *client)
	{
	struct lm92_data *data = i2c_get_clientdata(client);

	hwmon_device_unregister(data->hwmon_dev);
	sysfs_remove_group(&client->dev.kobj, &lm92_group);

	return 0;
	}


	/*
	* Module and driver stuff
	*/

	static const struct i2c_device_id lm92_id[] = {
	{ "lm92", 0 },
	/* max6635 could be added here */
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, lm92_id);

	static struct i2c_driver lm92_driver = {
	.class = I2C_CLASS_HWMON,
	.driver = {
	.name = "lm92",
	},
	.probe = lm92_probe,
	.remove = lm92_remove,
	.id_table = lm92_id,
	.detect = lm92_detect,
	.address_list = normal_i2c,
	};

	module_i2c_driver(lm92_driver);

	MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
	MODULE_DESCRIPTION("LM92/MAX6635 driver");
	MODULE_LICENSE("GPL");