drivers/hwmon/lm75.c

/*
 * lm75.c - Part of lm_sensors, Linux kernel modules for hardware
 *	 monitoring
 * Copyright (c) 1998, 1999  Frodo Looijaard <frodol@dds.nl>
 *
 * 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/jiffies.h>
#include <linux/i2c.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/err.h>
#include <linux/mutex.h>
#include "lm75.h"


/*
 * This driver handles the LM75 and compatible digital temperature sensors.
 */

enum lm75_type {		/* keep sorted in alphabetical order */
	ds1775,
	ds75,
	lm75,
	lm75a,
	max6625,
	max6626,
	mcp980x,
	stds75,
	tcn75,
	tmp100,
	tmp101,
	tmp105,
	tmp175,
	tmp275,
	tmp75,
};

/* Addresses scanned */
static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 0x4c,
					0x4d, 0x4e, 0x4f, I2C_CLIENT_END };


/* The LM75 registers */
#define LM75_REG_CONF		0x01
static const u8 LM75_REG_TEMP[3] = {
	0x00,		/* input */
	0x03,		/* max */
	0x02,		/* hyst */
};

/* Each client has this additional data */
struct lm75_data {
	struct device		*hwmon_dev;
	struct mutex		update_lock;
	u8			orig_conf;
	char			valid;		/* !=0 if registers are valid */
	unsigned long		last_updated;	/* In jiffies */
	u16			temp[3];	/* Register values,
						   0 = input
						   1 = max
						   2 = hyst */
};

static int lm75_read_value(struct i2c_client *client, u8 reg);
static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value);
static struct lm75_data *lm75_update_device(struct device *dev);


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

/* sysfs attributes for hwmon */

static ssize_t show_temp(struct device *dev, struct device_attribute *da,
			 char *buf)
{
	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
	struct lm75_data *data = lm75_update_device(dev);
	return sprintf(buf, "%d\n",
		       LM75_TEMP_FROM_REG(data->temp[attr->index]));
}

static ssize_t set_temp(struct device *dev, struct device_attribute *da,
			const char *buf, size_t count)
{
	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
	struct i2c_client *client = to_i2c_client(dev);
	struct lm75_data *data = i2c_get_clientdata(client);
	int nr = attr->index;
	long temp;
	int error;

	error = strict_strtol(buf, 10, &temp);
	if (error)
		return error;

	mutex_lock(&data->update_lock);
	data->temp[nr] = LM75_TEMP_TO_REG(temp);
	lm75_write_value(client, LM75_REG_TEMP[nr], data->temp[nr]);
	mutex_unlock(&data->update_lock);
	return count;
}

static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO,
			show_temp, set_temp, 1);
static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IWUSR | S_IRUGO,
			show_temp, set_temp, 2);
static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, 0);

static struct attribute *lm75_attributes[] = {
	&sensor_dev_attr_temp1_input.dev_attr.attr,
	&sensor_dev_attr_temp1_max.dev_attr.attr,
	&sensor_dev_attr_temp1_max_hyst.dev_attr.attr,

	NULL
};

static const struct attribute_group lm75_group = {
	.attrs = lm75_attributes,
};

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

/* device probe and removal */

static int
lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
	struct lm75_data *data;
	int status;
	u8 set_mask, clr_mask;
	int new;

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

	data = kzalloc(sizeof(struct lm75_data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;

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

	/* Set to LM75 resolution (9 bits, 1/2 degree C) and range.
	 * Then tweak to be more precise when appropriate.
	 */
	set_mask = 0;
	clr_mask = (1 << 0)			/* continuous conversions */
		| (1 << 6) | (1 << 5);		/* 9-bit mode */

	/* configure as specified */
	status = lm75_read_value(client, LM75_REG_CONF);
	if (status < 0) {
		dev_dbg(&client->dev, "Can't read config? %d\n", status);
		goto exit_free;
	}
	data->orig_conf = status;
	new = status & ~clr_mask;
	new |= set_mask;
	if (status != new)
		lm75_write_value(client, LM75_REG_CONF, new);
	dev_dbg(&client->dev, "Config %02x\n", new);

	/* Register sysfs hooks */
	status = sysfs_create_group(&client->dev.kobj, &lm75_group);
	if (status)
		goto exit_free;

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

	dev_info(&client->dev, "%s: sensor '%s'\n",
		 dev_name(data->hwmon_dev), client->name);

	return 0;

exit_remove:
	sysfs_remove_group(&client->dev.kobj, &lm75_group);
exit_free:
	kfree(data);
	return status;
}

static int lm75_remove(struct i2c_client *client)
{
	struct lm75_data *data = i2c_get_clientdata(client);

	hwmon_device_unregister(data->hwmon_dev);
	sysfs_remove_group(&client->dev.kobj, &lm75_group);
	lm75_write_value(client, LM75_REG_CONF, data->orig_conf);
	kfree(data);
	return 0;
}

static const struct i2c_device_id lm75_ids[] = {
	{ "ds1775", ds1775, },
	{ "ds75", ds75, },
	{ "lm75", lm75, },
	{ "lm75a", lm75a, },
	{ "max6625", max6625, },
	{ "max6626", max6626, },
	{ "mcp980x", mcp980x, },
	{ "stds75", stds75, },
	{ "tcn75", tcn75, },
	{ "tmp100", tmp100, },
	{ "tmp101", tmp101, },
	{ "tmp105", tmp105, },
	{ "tmp175", tmp175, },
	{ "tmp275", tmp275, },
	{ "tmp75", tmp75, },
	{ /* LIST END */ }
};
MODULE_DEVICE_TABLE(i2c, lm75_ids);

#define LM75A_ID 0xA1

/* Return 0 if detection is successful, -ENODEV otherwise */
static int lm75_detect(struct i2c_client *new_client,
		       struct i2c_board_info *info)
{
	struct i2c_adapter *adapter = new_client->adapter;
	int i;
	int conf, hyst, os;
	bool is_lm75a = 0;

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

	/* Now, we do the remaining detection. There is no identification-
	   dedicated register so we have to rely on several tricks:
	   unused bits, registers cycling over 8-address boundaries,
	   addresses 0x04-0x07 returning the last read value.
	   The cycling+unused addresses combination is not tested,
	   since it would significantly slow the detection down and would
	   hardly add any value.

	   The National Semiconductor LM75A is different than earlier
	   LM75s.  It has an ID byte of 0xaX (where X is the chip
	   revision, with 1 being the only revision in existence) in
	   register 7, and unused registers return 0xff rather than the
	   last read value. */

	/* Unused bits */
	conf = i2c_smbus_read_byte_data(new_client, 1);
	if (conf & 0xe0)
		return -ENODEV;

	/* First check for LM75A */
	if (i2c_smbus_read_byte_data(new_client, 7) == LM75A_ID) {
		/* LM75A returns 0xff on unused registers so
		   just to be sure we check for that too. */
		if (i2c_smbus_read_byte_data(new_client, 4) != 0xff
		 || i2c_smbus_read_byte_data(new_client, 5) != 0xff
		 || i2c_smbus_read_byte_data(new_client, 6) != 0xff)
			return -ENODEV;
		is_lm75a = 1;
		hyst = i2c_smbus_read_byte_data(new_client, 2);
		os = i2c_smbus_read_byte_data(new_client, 3);
	} else { /* Traditional style LM75 detection */
		/* Unused addresses */
		hyst = i2c_smbus_read_byte_data(new_client, 2);
		if (i2c_smbus_read_byte_data(new_client, 4) != hyst
		 || i2c_smbus_read_byte_data(new_client, 5) != hyst
		 || i2c_smbus_read_byte_data(new_client, 6) != hyst
		 || i2c_smbus_read_byte_data(new_client, 7) != hyst)
			return -ENODEV;
		os = i2c_smbus_read_byte_data(new_client, 3);
		if (i2c_smbus_read_byte_data(new_client, 4) != os
		 || i2c_smbus_read_byte_data(new_client, 5) != os
		 || i2c_smbus_read_byte_data(new_client, 6) != os
		 || i2c_smbus_read_byte_data(new_client, 7) != os)
			return -ENODEV;
	}

	/* Addresses cycling */
	for (i = 8; i <= 248; i += 40) {
		if (i2c_smbus_read_byte_data(new_client, i + 1) != conf
		 || i2c_smbus_read_byte_data(new_client, i + 2) != hyst
		 || i2c_smbus_read_byte_data(new_client, i + 3) != os)
			return -ENODEV;
		if (is_lm75a && i2c_smbus_read_byte_data(new_client, i + 7)
				!= LM75A_ID)
			return -ENODEV;
	}

	strlcpy(info->type, is_lm75a ? "lm75a" : "lm75", I2C_NAME_SIZE);

	return 0;
}

#ifdef CONFIG_PM
static int lm75_suspend(struct device *dev)
{
	int status;
	struct i2c_client *client = to_i2c_client(dev);
	status = lm75_read_value(client, LM75_REG_CONF);
	if (status < 0) {
		dev_dbg(&client->dev, "Can't read config? %d\n", status);
		return status;
	}
	status = status | LM75_SHUTDOWN;
	lm75_write_value(client, LM75_REG_CONF, status);
	return 0;
}

static int lm75_resume(struct device *dev)
{
	int status;
	struct i2c_client *client = to_i2c_client(dev);
	status = lm75_read_value(client, LM75_REG_CONF);
	if (status < 0) {
		dev_dbg(&client->dev, "Can't read config? %d\n", status);
		return status;
	}
	status = status & ~LM75_SHUTDOWN;
	lm75_write_value(client, LM75_REG_CONF, status);
	return 0;
}

static const struct dev_pm_ops lm75_dev_pm_ops = {
	.suspend	= lm75_suspend,
	.resume		= lm75_resume,
};
#define LM75_DEV_PM_OPS (&lm75_dev_pm_ops)
#else
#define LM75_DEV_PM_OPS NULL
#endif /* CONFIG_PM */

static struct i2c_driver lm75_driver = {
	.class		= I2C_CLASS_HWMON,
	.driver = {
		.name	= "lm75",
		.pm	= LM75_DEV_PM_OPS,
	},
	.probe		= lm75_probe,
	.remove		= lm75_remove,
	.id_table	= lm75_ids,
	.detect		= lm75_detect,
	.address_list	= normal_i2c,
};

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

/* register access */

/*
 * All registers are word-sized, except for the configuration register.
 * LM75 uses a high-byte first convention, which is exactly opposite to
 * the SMBus standard.
 */
static int lm75_read_value(struct i2c_client *client, u8 reg)
{
	int value;

	if (reg == LM75_REG_CONF)
		return i2c_smbus_read_byte_data(client, reg);

	value = i2c_smbus_read_word_data(client, reg);
	return (value < 0) ? value : swab16(value);
}

static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value)
{
	if (reg == LM75_REG_CONF)
		return i2c_smbus_write_byte_data(client, reg, value);
	else
		return i2c_smbus_write_word_data(client, reg, swab16(value));
}

static struct lm75_data *lm75_update_device(struct device *dev)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct lm75_data *data = i2c_get_clientdata(client);

	mutex_lock(&data->update_lock);

	if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
	    || !data->valid) {
		int i;
		dev_dbg(&client->dev, "Starting lm75 update\n");

		for (i = 0; i < ARRAY_SIZE(data->temp); i++) {
			int status;

			status = lm75_read_value(client, LM75_REG_TEMP[i]);
			if (status < 0)
				dev_dbg(&client->dev, "reg %d, err %d\n",
						LM75_REG_TEMP[i], status);
			else
				data->temp[i] = status;
		}
		data->last_updated = jiffies;
		data->valid = 1;
	}

	mutex_unlock(&data->update_lock);

	return data;
}

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

/* module glue */

static int __init sensors_lm75_init(void)
{
	return i2c_add_driver(&lm75_driver);
}

static void __exit sensors_lm75_exit(void)
{
	i2c_del_driver(&lm75_driver);
}

MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>");
MODULE_DESCRIPTION("LM75 driver");
MODULE_LICENSE("GPL");

module_init(sensors_lm75_init);
module_exit(sensors_lm75_exit);