[PATCH] hwmon: Fix negative temperature readings in lm77 driver

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / hwmon / lm77.c

/*
    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

    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/err.h>

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

/* Insmod parameters */
I2C_CLIENT_INSMOD_1(lm77);

/* 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

/* Each client has this additional data */
struct lm77_data {
        struct i2c_client       client;
        struct class_device *class_dev;
        struct semaphore        update_lock;
        char                    valid;
        unsigned long           last_updated;   /* In jiffies */
        int                     temp_input;     /* Temperatures */
        int                     temp_crit;
        int                     temp_min;
        int                     temp_max;
        int                     temp_hyst;
        u8                      alarms;
};

static int lm77_attach_adapter(struct i2c_adapter *adapter);
static int lm77_detect(struct i2c_adapter *adapter, int address, int kind);
static void lm77_init_client(struct i2c_client *client);
static int lm77_detach_client(struct i2c_client *client);
static u16 lm77_read_value(struct i2c_client *client, u8 reg);
static int lm77_write_value(struct i2c_client *client, u8 reg, u16 value);

static struct lm77_data *lm77_update_device(struct device *dev);


/* This is the driver that will be inserted */
static struct i2c_driver lm77_driver = {
        .driver = {
                .name   = "lm77",
        },
        .attach_adapter = lm77_attach_adapter,
        .detach_client  = lm77_detach_client,
};

/* 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)
{
        int ntemp = SENSORS_LIMIT(temp, LM77_TEMP_MIN, LM77_TEMP_MAX);
        return (ntemp / 500) * 8;
}

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

/* sysfs stuff */

/* read routines for temperature limits */
#define show(value)     \
static ssize_t show_##value(struct device *dev, struct device_attribute *attr, char *buf)       \
{                                                               \
        struct lm77_data *data = lm77_update_device(dev);       \
        return sprintf(buf, "%d\n", data->value);               \
}

show(temp_input);
show(temp_crit);
show(temp_min);
show(temp_max);
show(alarms);

/* read routines for hysteresis values */
static ssize_t show_temp_crit_hyst(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct lm77_data *data = lm77_update_device(dev);
        return sprintf(buf, "%d\n", data->temp_crit - data->temp_hyst);
}
static ssize_t show_temp_min_hyst(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct lm77_data *data = lm77_update_device(dev);
        return sprintf(buf, "%d\n", data->temp_min + data->temp_hyst);
}
static ssize_t show_temp_max_hyst(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct lm77_data *data = lm77_update_device(dev);
        return sprintf(buf, "%d\n", data->temp_max - data->temp_hyst);
}

/* write routines */
#define set(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 lm77_data *data = i2c_get_clientdata(client);                    \
        long val = simple_strtoul(buf, NULL, 10);                               \
                                                                                \
        down(&data->update_lock);                                               \
        data->value = val;                              \
        lm77_write_value(client, reg, LM77_TEMP_TO_REG(data->value));           \
        up(&data->update_lock);                                                 \
        return count;                                                           \
}

set(temp_min, LM77_REG_TEMP_MIN);
set(temp_max, LM77_REG_TEMP_MAX);

/* hysteresis is stored as a relative value on the chip, so it has to be
   converted first */
static ssize_t set_temp_crit_hyst(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct lm77_data *data = i2c_get_clientdata(client);
        unsigned long val = simple_strtoul(buf, NULL, 10);

        down(&data->update_lock);
        data->temp_hyst = data->temp_crit - val;
        lm77_write_value(client, LM77_REG_TEMP_HYST,
                         LM77_TEMP_TO_REG(data->temp_hyst));
        up(&data->update_lock);
        return count;
}

/* preserve hysteresis when setting T_crit */
static ssize_t set_temp_crit(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct lm77_data *data = i2c_get_clientdata(client);
        long val = simple_strtoul(buf, NULL, 10);
        int oldcrithyst;
        
        down(&data->update_lock);
        oldcrithyst = data->temp_crit - data->temp_hyst;
        data->temp_crit = val;
        data->temp_hyst = data->temp_crit - oldcrithyst;
        lm77_write_value(client, LM77_REG_TEMP_CRIT,
                         LM77_TEMP_TO_REG(data->temp_crit));
        lm77_write_value(client, LM77_REG_TEMP_HYST,
                         LM77_TEMP_TO_REG(data->temp_hyst));
        up(&data->update_lock);
        return count;
}

static DEVICE_ATTR(temp1_input, S_IRUGO,
                   show_temp_input, NULL);
static DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO,
                   show_temp_crit, set_temp_crit);
static DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO,
                   show_temp_min, set_temp_min);
static DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO,
                   show_temp_max, set_temp_max);

static DEVICE_ATTR(temp1_crit_hyst, S_IWUSR | S_IRUGO,
                   show_temp_crit_hyst, set_temp_crit_hyst);
static DEVICE_ATTR(temp1_min_hyst, S_IRUGO,
                   show_temp_min_hyst, NULL);
static DEVICE_ATTR(temp1_max_hyst, S_IRUGO,
                   show_temp_max_hyst, NULL);

static DEVICE_ATTR(alarms, S_IRUGO,
                   show_alarms, NULL);

static int lm77_attach_adapter(struct i2c_adapter *adapter)
{
        if (!(adapter->class & I2C_CLASS_HWMON))
                return 0;
        return i2c_probe(adapter, &addr_data, lm77_detect);
}

/* This function is called by i2c_probe */
static int lm77_detect(struct i2c_adapter *adapter, int address, int kind)
{
        struct i2c_client *new_client;
        struct lm77_data *data;
        int err = 0;
        const char *name = "";

        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
                                     I2C_FUNC_SMBUS_WORD_DATA))
                goto exit;

        /* OK. For now, we presume we have a valid client. We now create the
           client structure, even though we cannot fill it completely yet.
           But it allows us to access lm77_{read,write}_value. */
        if (!(data = kzalloc(sizeof(struct lm77_data), GFP_KERNEL))) {
                err = -ENOMEM;
                goto exit;
        }

        new_client = &data->client;
        i2c_set_clientdata(new_client, data);
        new_client->addr = address;
        new_client->adapter = adapter;
        new_client->driver = &lm77_driver;
        new_client->flags = 0;

        /* 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. */
        if (kind < 0) {
                int i, cur, conf, hyst, crit, min, max;

                /* addresses cycling */
                cur = i2c_smbus_read_word_data(new_client, 0);
                conf = i2c_smbus_read_byte_data(new_client, 1);
                hyst = i2c_smbus_read_word_data(new_client, 2);
                crit = i2c_smbus_read_word_data(new_client, 3);
                min = i2c_smbus_read_word_data(new_client, 4);
                max = i2c_smbus_read_word_data(new_client, 5);
                for (i = 8; i <= 0xff; i += 8)
                        if (i2c_smbus_read_byte_data(new_client, i + 1) != conf
                            || i2c_smbus_read_word_data(new_client, i + 2) != hyst
                            || i2c_smbus_read_word_data(new_client, i + 3) != crit
                            || i2c_smbus_read_word_data(new_client, i + 4) != min
                            || i2c_smbus_read_word_data(new_client, i + 5) != max)
                                goto exit_free;

                /* 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))
                        goto exit_free;

                /* unused bits */
                if (conf & 0xe0)
                        goto exit_free;

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

        }

        /* Determine the chip type - only one kind supported! */
        if (kind <= 0)
                kind = lm77;

        if (kind == lm77) {
                name = "lm77";
        }

        /* Fill in the remaining client fields and put it into the global list */
        strlcpy(new_client->name, name, I2C_NAME_SIZE);
        data->valid = 0;
        init_MUTEX(&data->update_lock);

        /* Tell the I2C layer a new client has arrived */
        if ((err = i2c_attach_client(new_client)))
                goto exit_free;

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

        /* Register sysfs hooks */
        data->class_dev = hwmon_device_register(&new_client->dev);
        if (IS_ERR(data->class_dev)) {
                err = PTR_ERR(data->class_dev);
                goto exit_detach;
        }

        device_create_file(&new_client->dev, &dev_attr_temp1_input);
        device_create_file(&new_client->dev, &dev_attr_temp1_crit);
        device_create_file(&new_client->dev, &dev_attr_temp1_min);
        device_create_file(&new_client->dev, &dev_attr_temp1_max);
        device_create_file(&new_client->dev, &dev_attr_temp1_crit_hyst);
        device_create_file(&new_client->dev, &dev_attr_temp1_min_hyst);
        device_create_file(&new_client->dev, &dev_attr_temp1_max_hyst);
        device_create_file(&new_client->dev, &dev_attr_alarms);
        return 0;

exit_detach:
        i2c_detach_client(new_client);
exit_free:
        kfree(data);
exit:
        return err;
}

static int lm77_detach_client(struct i2c_client *client)
{
        struct lm77_data *data = i2c_get_clientdata(client);
        hwmon_device_unregister(data->class_dev);
        i2c_detach_client(client);
        kfree(data);
        return 0;
}

/* 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 swab16(i2c_smbus_read_word_data(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_data(client, reg, swab16(value));
}

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 struct lm77_data *lm77_update_device(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct lm77_data *data = i2c_get_clientdata(client);

        down(&data->update_lock);

        if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
            || !data->valid) {
                dev_dbg(&client->dev, "Starting lm77 update\n");
                data->temp_input =
                        LM77_TEMP_FROM_REG(lm77_read_value(client,
                                                           LM77_REG_TEMP));
                data->temp_hyst =
                        LM77_TEMP_FROM_REG(lm77_read_value(client,
                                                           LM77_REG_TEMP_HYST));
                data->temp_crit =
                        LM77_TEMP_FROM_REG(lm77_read_value(client,
                                                           LM77_REG_TEMP_CRIT));
                data->temp_min =
                        LM77_TEMP_FROM_REG(lm77_read_value(client,
                                                           LM77_REG_TEMP_MIN));
                data->temp_max =
                        LM77_TEMP_FROM_REG(lm77_read_value(client,
                                                           LM77_REG_TEMP_MAX));
                data->alarms =
                        lm77_read_value(client, LM77_REG_TEMP) & 0x0007;
                data->last_updated = jiffies;
                data->valid = 1;
        }

        up(&data->update_lock);

        return data;
}

static int __init sensors_lm77_init(void)
{
        return i2c_add_driver(&lm77_driver);
}

static void __exit sensors_lm77_exit(void)
{
        i2c_del_driver(&lm77_driver);
}

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

module_init(sensors_lm77_init);
module_exit(sensors_lm77_exit);