tmp421.c

Go to the documentation of this file.

/* tmp421.c
 *
 * Copyright (C) 2009 Andre Prendel <[email protected]>
 * Preliminary support by:
 * Melvin Rook, Raymond Ng
 *
 * 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.
 */

/*
 * Driver for the Texas Instruments TMP421 SMBus temperature sensor IC.
 * Supported models: TMP421, TMP422, TMP423
 */

#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 <linux/sysfs.h>

/* Addresses to scan */
static const unsigned short normal_i2c[] = { 0x2a, 0x4c, 0x4d, 0x4e, 0x4f,
                         I2C_CLIENT_END };

enum chips { tmp421, tmp422, tmp423 };

/* The TMP421 registers */
#define TMP421_CONFIG_REG_1         0x09
#define TMP421_CONVERSION_RATE_REG      0x0B
#define TMP421_MANUFACTURER_ID_REG      0xFE
#define TMP421_DEVICE_ID_REG            0xFF

static const u8 TMP421_TEMP_MSB[4]      = { 0x00, 0x01, 0x02, 0x03 };
static const u8 TMP421_TEMP_LSB[4]      = { 0x10, 0x11, 0x12, 0x13 };

/* Flags */
#define TMP421_CONFIG_SHUTDOWN          0x40
#define TMP421_CONFIG_RANGE         0x04

/* Manufacturer / Device ID's */
#define TMP421_MANUFACTURER_ID          0x55
#define TMP421_DEVICE_ID            0x21
#define TMP422_DEVICE_ID            0x22
#define TMP423_DEVICE_ID            0x23

static const struct i2c_device_id tmp421_id[] = {
    { "tmp421", 2 },
    { "tmp422", 3 },
    { "tmp423", 4 },
    { }
};
MODULE_DEVICE_TABLE(i2c, tmp421_id);

struct tmp421_data {
    struct device *hwmon_dev;
    struct mutex update_lock;
    char valid;
    unsigned long last_updated;
    int channels;
    u8 config;
    s16 temp[4];
};

static int temp_from_s16(s16 reg)
{
    /* Mask out status bits */
    int temp = reg & ~0xf;

    return (temp * 1000 + 128) / 256;
}

static int temp_from_u16(u16 reg)
{
    /* Mask out status bits */
    int temp = reg & ~0xf;

    /* Add offset for extended temperature range. */
    temp -= 64 * 256;

    return (temp * 1000 + 128) / 256;
}

static struct tmp421_data *tmp421_update_device(struct device *dev)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct tmp421_data *data = i2c_get_clientdata(client);
    int i;

    mutex_lock(&data->update_lock);

    if (time_after(jiffies, data->last_updated + 2 * HZ) || !data->valid) {
        data->config = i2c_smbus_read_byte_data(client,
            TMP421_CONFIG_REG_1);

        for (i = 0; i < data->channels; i++) {
            data->temp[i] = i2c_smbus_read_byte_data(client,
                TMP421_TEMP_MSB[i]) << 8;
            data->temp[i] |= i2c_smbus_read_byte_data(client,
                TMP421_TEMP_LSB[i]);
        }
        data->last_updated = jiffies;
        data->valid = 1;
    }

    mutex_unlock(&data->update_lock);

    return data;
}

static ssize_t show_temp_value(struct device *dev,
                   struct device_attribute *devattr, char *buf)
{
    int index = to_sensor_dev_attr(devattr)->index;
    struct tmp421_data *data = tmp421_update_device(dev);
    int temp;

    mutex_lock(&data->update_lock);
    if (data->config & TMP421_CONFIG_RANGE)
        temp = temp_from_u16(data->temp[index]);
    else
        temp = temp_from_s16(data->temp[index]);
    mutex_unlock(&data->update_lock);

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

static ssize_t show_fault(struct device *dev,
              struct device_attribute *devattr, char *buf)
{
    int index = to_sensor_dev_attr(devattr)->index;
    struct tmp421_data *data = tmp421_update_device(dev);

    /*
     * The OPEN bit signals a fault. This is bit 0 of the temperature
     * register (low byte).
     */
    if (data->temp[index] & 0x01)
        return sprintf(buf, "1\n");
    else
        return sprintf(buf, "0\n");
}

static umode_t tmp421_is_visible(struct kobject *kobj, struct attribute *a,
                int n)
{
    struct device *dev = container_of(kobj, struct device, kobj);
    struct tmp421_data *data = dev_get_drvdata(dev);
    struct device_attribute *devattr;
    unsigned int index;

    devattr = container_of(a, struct device_attribute, attr);
    index = to_sensor_dev_attr(devattr)->index;

    if (index < data->channels)
        return a->mode;

    return 0;
}

static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp_value, NULL, 0);
static SENSOR_DEVICE_ATTR(temp2_input, S_IRUGO, show_temp_value, NULL, 1);
static SENSOR_DEVICE_ATTR(temp2_fault, S_IRUGO, show_fault, NULL, 1);
static SENSOR_DEVICE_ATTR(temp3_input, S_IRUGO, show_temp_value, NULL, 2);
static SENSOR_DEVICE_ATTR(temp3_fault, S_IRUGO, show_fault, NULL, 2);
static SENSOR_DEVICE_ATTR(temp4_input, S_IRUGO, show_temp_value, NULL, 3);
static SENSOR_DEVICE_ATTR(temp4_fault, S_IRUGO, show_fault, NULL, 3);

static struct attribute *tmp421_attr[] = {
    &sensor_dev_attr_temp1_input.dev_attr.attr,
    &sensor_dev_attr_temp2_input.dev_attr.attr,
    &sensor_dev_attr_temp2_fault.dev_attr.attr,
    &sensor_dev_attr_temp3_input.dev_attr.attr,
    &sensor_dev_attr_temp3_fault.dev_attr.attr,
    &sensor_dev_attr_temp4_input.dev_attr.attr,
    &sensor_dev_attr_temp4_fault.dev_attr.attr,
    NULL
};

static const struct attribute_group tmp421_group = {
    .attrs = tmp421_attr,
    .is_visible = tmp421_is_visible,
};

static int tmp421_init_client(struct i2c_client *client)
{
    int config, config_orig;

    /* Set the conversion rate to 2 Hz */
    i2c_smbus_write_byte_data(client, TMP421_CONVERSION_RATE_REG, 0x05);

    /* Start conversions (disable shutdown if necessary) */
    config = i2c_smbus_read_byte_data(client, TMP421_CONFIG_REG_1);
    if (config < 0) {
        dev_err(&client->dev, "Could not read configuration"
             " register (%d)\n", config);
        return -ENODEV;
    }

    config_orig = config;
    config &= ~TMP421_CONFIG_SHUTDOWN;

    if (config != config_orig) {
        dev_info(&client->dev, "Enable monitoring chip\n");
        i2c_smbus_write_byte_data(client, TMP421_CONFIG_REG_1, config);
    }

    return 0;
}

static int tmp421_detect(struct i2c_client *client,
             struct i2c_board_info *info)
{
    enum chips kind;
    struct i2c_adapter *adapter = client->adapter;
    const char *names[] = { "TMP421", "TMP422", "TMP423" };
    u8 reg;

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

    reg = i2c_smbus_read_byte_data(client, TMP421_MANUFACTURER_ID_REG);
    if (reg != TMP421_MANUFACTURER_ID)
        return -ENODEV;

    reg = i2c_smbus_read_byte_data(client, TMP421_DEVICE_ID_REG);
    switch (reg) {
    case TMP421_DEVICE_ID:
        kind = tmp421;
        break;
    case TMP422_DEVICE_ID:
        kind = tmp422;
        break;
    case TMP423_DEVICE_ID:
        kind = tmp423;
        break;
    default:
        return -ENODEV;
    }

    strlcpy(info->type, tmp421_id[kind].name, I2C_NAME_SIZE);
    dev_info(&adapter->dev, "Detected TI %s chip at 0x%02x\n",
         names[kind], client->addr);

    return 0;
}

static int tmp421_probe(struct i2c_client *client,
            const struct i2c_device_id *id)
{
    struct tmp421_data *data;
    int err;

    data = devm_kzalloc(&client->dev, sizeof(struct tmp421_data),
                GFP_KERNEL);
    if (!data)
        return -ENOMEM;

    i2c_set_clientdata(client, data);
    mutex_init(&data->update_lock);
    data->channels = id->driver_data;

    err = tmp421_init_client(client);
    if (err)
        return err;

    err = sysfs_create_group(&client->dev.kobj, &tmp421_group);
    if (err)
        return err;

    data->hwmon_dev = hwmon_device_register(&client->dev);
    if (IS_ERR(data->hwmon_dev)) {
        err = PTR_ERR(data->hwmon_dev);
        data->hwmon_dev = NULL;
        goto exit_remove;
    }
    return 0;

exit_remove:
    sysfs_remove_group(&client->dev.kobj, &tmp421_group);
    return err;
}

static int tmp421_remove(struct i2c_client *client)
{
    struct tmp421_data *data = i2c_get_clientdata(client);

    hwmon_device_unregister(data->hwmon_dev);
    sysfs_remove_group(&client->dev.kobj, &tmp421_group);

    return 0;
}

static struct i2c_driver tmp421_driver = {
    .class = I2C_CLASS_HWMON,
    .driver = {
        .name   = "tmp421",
    },
    .probe = tmp421_probe,
    .remove = tmp421_remove,
    .id_table = tmp421_id,
    .detect = tmp421_detect,
    .address_list = normal_i2c,
};

module_i2c_driver(tmp421_driver);

MODULE_AUTHOR("Andre Prendel <[email protected]>");
MODULE_DESCRIPTION("Texas Instruments TMP421/422/423 temperature sensor"
           " driver");
MODULE_LICENSE("GPL");