max6639.c

/*
 * max6639.c - Support for Maxim MAX6639
 *
 * 2-Channel Temperature Monitor with Dual PWM Fan-Speed Controller
 *
 * Copyright (C) 2010, 2011 Roland Stigge <[email protected]>
 *
 * based on the initial MAX6639 support from semptian.net
 * by He Changqing <[email protected]>
 *
 * 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 <linux/i2c/max6639.h>

/* Addresses to scan */
static unsigned short normal_i2c[] = { 0x2c, 0x2e, 0x2f, I2C_CLIENT_END };

/* The MAX6639 registers, valid channel numbers: 0, 1 */
#define MAX6639_REG_TEMP(ch)            (0x00 + (ch))
#define MAX6639_REG_STATUS            0x02
#define MAX6639_REG_OUTPUT_MASK            0x03
#define MAX6639_REG_GCONFIG            0x04
#define MAX6639_REG_TEMP_EXT(ch)        (0x05 + (ch))
#define MAX6639_REG_ALERT_LIMIT(ch)        (0x08 + (ch))
#define MAX6639_REG_OT_LIMIT(ch)        (0x0A + (ch))
#define MAX6639_REG_THERM_LIMIT(ch)        (0x0C + (ch))
#define MAX6639_REG_FAN_CONFIG1(ch)        (0x10 + (ch) * 4)
#define MAX6639_REG_FAN_CONFIG2a(ch)        (0x11 + (ch) * 4)
#define MAX6639_REG_FAN_CONFIG2b(ch)        (0x12 + (ch) * 4)
#define MAX6639_REG_FAN_CONFIG3(ch)        (0x13 + (ch) * 4)
#define MAX6639_REG_FAN_CNT(ch)            (0x20 + (ch))
#define MAX6639_REG_TARGET_CNT(ch)        (0x22 + (ch))
#define MAX6639_REG_FAN_PPR(ch)            (0x24 + (ch))
#define MAX6639_REG_TARGTDUTY(ch)        (0x26 + (ch))
#define MAX6639_REG_FAN_START_TEMP(ch)        (0x28 + (ch))
#define MAX6639_REG_DEVID            0x3D
#define MAX6639_REG_MANUID            0x3E
#define MAX6639_REG_DEVREV            0x3F

/* Register bits */
#define MAX6639_GCONFIG_STANDBY            0x80
#define MAX6639_GCONFIG_POR            0x40
#define MAX6639_GCONFIG_DISABLE_TIMEOUT        0x20
#define MAX6639_GCONFIG_CH2_LOCAL        0x10
#define MAX6639_GCONFIG_PWM_FREQ_HI        0x08

#define MAX6639_FAN_CONFIG1_PWM            0x80

#define MAX6639_FAN_CONFIG3_THERM_FULL_SPEED    0x40

static const int rpm_ranges[] = { 2000, 4000, 8000, 16000 };

#define FAN_FROM_REG(val, div, rpm_range)    ((val) == 0 ? -1 : \
    (val) == 255 ? 0 : (rpm_ranges[rpm_range] * 30) / ((div + 1) * (val)))
#define TEMP_LIMIT_TO_REG(val)    SENSORS_LIMIT((val) / 1000, 0, 255)

/*
 * Client data (each client gets its own)
 */
struct max6639_data {
    struct device *hwmon_dev;
    struct mutex update_lock;
    char valid;        /* !=0 if following fields are valid */
    unsigned long last_updated;    /* In jiffies */

    /* Register values sampled regularly */
    u16 temp[2];        /* Temperature, in 1/8 C, 0..255 C */
    bool temp_fault[2];    /* Detected temperature diode failure */
    u8 fan[2];        /* Register value: TACH count for fans >=30 */
    u8 status;        /* Detected channel alarms and fan failures */

    /* Register values only written to */
    u8 pwm[2];        /* Register value: Duty cycle 0..120 */
    u8 temp_therm[2];    /* THERM Temperature, 0..255 C (->_max) */
    u8 temp_alert[2];    /* ALERT Temperature, 0..255 C (->_crit) */
    u8 temp_ot[2];        /* OT Temperature, 0..255 C (->_emergency) */

    /* Register values initialized only once */
    u8 ppr;            /* Pulses per rotation 0..3 for 1..4 ppr */
    u8 rpm_range;        /* Index in above rpm_ranges table */
};

static struct max6639_data *max6639_update_device(struct device *dev)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct max6639_data *data = i2c_get_clientdata(client);
    struct max6639_data *ret = data;
    int i;
    int status_reg;

    mutex_lock(&data->update_lock);

    if (time_after(jiffies, data->last_updated + 2 * HZ) || !data->valid) {
        int res;

        dev_dbg(&client->dev, "Starting max6639 update\n");

        status_reg = i2c_smbus_read_byte_data(client,
                              MAX6639_REG_STATUS);
        if (status_reg < 0) {
            ret = ERR_PTR(status_reg);
            goto abort;
        }

        data->status = status_reg;

        for (i = 0; i < 2; i++) {
            res = i2c_smbus_read_byte_data(client,
                    MAX6639_REG_FAN_CNT(i));
            if (res < 0) {
                ret = ERR_PTR(res);
                goto abort;
            }
            data->fan[i] = res;

            res = i2c_smbus_read_byte_data(client,
                    MAX6639_REG_TEMP_EXT(i));
            if (res < 0) {
                ret = ERR_PTR(res);
                goto abort;
            }
            data->temp[i] = res >> 5;
            data->temp_fault[i] = res & 0x01;

            res = i2c_smbus_read_byte_data(client,
                    MAX6639_REG_TEMP(i));
            if (res < 0) {
                ret = ERR_PTR(res);
                goto abort;
            }
            data->temp[i] |= res << 3;
        }

        data->last_updated = jiffies;
        data->valid = 1;
    }
abort:
    mutex_unlock(&data->update_lock);

    return ret;
}

static ssize_t show_temp_input(struct device *dev,
                   struct device_attribute *dev_attr, char *buf)
{
    long temp;
    struct max6639_data *data = max6639_update_device(dev);
    struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);

    if (IS_ERR(data))
        return PTR_ERR(data);

    temp = data->temp[attr->index] * 125;
    return sprintf(buf, "%ld\n", temp);
}

static ssize_t show_temp_fault(struct device *dev,
                   struct device_attribute *dev_attr, char *buf)
{
    struct max6639_data *data = max6639_update_device(dev);
    struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);

    if (IS_ERR(data))
        return PTR_ERR(data);

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

static ssize_t show_temp_max(struct device *dev,
                 struct device_attribute *dev_attr, char *buf)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct max6639_data *data = i2c_get_clientdata(client);
    struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);

    return sprintf(buf, "%d\n", (data->temp_therm[attr->index] * 1000));
}

static ssize_t set_temp_max(struct device *dev,
                struct device_attribute *dev_attr,
                const char *buf, size_t count)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct max6639_data *data = i2c_get_clientdata(client);
    struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
    unsigned long val;
    int res;

    res = strict_strtoul(buf, 10, &val);
    if (res)
        return res;

    mutex_lock(&data->update_lock);
    data->temp_therm[attr->index] = TEMP_LIMIT_TO_REG(val);
    i2c_smbus_write_byte_data(client,
                  MAX6639_REG_THERM_LIMIT(attr->index),
                  data->temp_therm[attr->index]);
    mutex_unlock(&data->update_lock);
    return count;
}

static ssize_t show_temp_crit(struct device *dev,
                  struct device_attribute *dev_attr, char *buf)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct max6639_data *data = i2c_get_clientdata(client);
    struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);

    return sprintf(buf, "%d\n", (data->temp_alert[attr->index] * 1000));
}

static ssize_t set_temp_crit(struct device *dev,
                 struct device_attribute *dev_attr,
                 const char *buf, size_t count)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct max6639_data *data = i2c_get_clientdata(client);
    struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
    unsigned long val;
    int res;

    res = strict_strtoul(buf, 10, &val);
    if (res)
        return res;

    mutex_lock(&data->update_lock);
    data->temp_alert[attr->index] = TEMP_LIMIT_TO_REG(val);
    i2c_smbus_write_byte_data(client,
                  MAX6639_REG_ALERT_LIMIT(attr->index),
                  data->temp_alert[attr->index]);
    mutex_unlock(&data->update_lock);
    return count;
}

static ssize_t show_temp_emergency(struct device *dev,
                   struct device_attribute *dev_attr,
                   char *buf)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct max6639_data *data = i2c_get_clientdata(client);
    struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);

    return sprintf(buf, "%d\n", (data->temp_ot[attr->index] * 1000));
}

static ssize_t set_temp_emergency(struct device *dev,
                  struct device_attribute *dev_attr,
                  const char *buf, size_t count)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct max6639_data *data = i2c_get_clientdata(client);
    struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
    unsigned long val;
    int res;

    res = strict_strtoul(buf, 10, &val);
    if (res)
        return res;

    mutex_lock(&data->update_lock);
    data->temp_ot[attr->index] = TEMP_LIMIT_TO_REG(val);
    i2c_smbus_write_byte_data(client,
                  MAX6639_REG_OT_LIMIT(attr->index),
                  data->temp_ot[attr->index]);
    mutex_unlock(&data->update_lock);
    return count;
}

static ssize_t show_pwm(struct device *dev,
            struct device_attribute *dev_attr, char *buf)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct max6639_data *data = i2c_get_clientdata(client);
    struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);

    return sprintf(buf, "%d\n", data->pwm[attr->index] * 255 / 120);
}

static ssize_t set_pwm(struct device *dev,
               struct device_attribute *dev_attr,
               const char *buf, size_t count)
{
    struct i2c_client *client = to_i2c_client(dev);
    struct max6639_data *data = i2c_get_clientdata(client);
    struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
    unsigned long val;
    int res;

    res = strict_strtoul(buf, 10, &val);
    if (res)
        return res;

    val = SENSORS_LIMIT(val, 0, 255);

    mutex_lock(&data->update_lock);
    data->pwm[attr->index] = (u8)(val * 120 / 255);
    i2c_smbus_write_byte_data(client,
                  MAX6639_REG_TARGTDUTY(attr->index),
                  data->pwm[attr->index]);
    mutex_unlock(&data->update_lock);
    return count;
}

static ssize_t show_fan_input(struct device *dev,
                  struct device_attribute *dev_attr, char *buf)
{
    struct max6639_data *data = max6639_update_device(dev);
    struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);

    if (IS_ERR(data))
        return PTR_ERR(data);

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

static ssize_t show_alarm(struct device *dev,
              struct device_attribute *dev_attr, char *buf)
{
    struct max6639_data *data = max6639_update_device(dev);
    struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);

    if (IS_ERR(data))
        return PTR_ERR(data);

    return sprintf(buf, "%d\n", !!(data->status & (1 << attr->index)));
}

static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp_input, NULL, 0);
static SENSOR_DEVICE_ATTR(temp2_input, S_IRUGO, show_temp_input, NULL, 1);
static SENSOR_DEVICE_ATTR(temp1_fault, S_IRUGO, show_temp_fault, NULL, 0);
static SENSOR_DEVICE_ATTR(temp2_fault, S_IRUGO, show_temp_fault, NULL, 1);
static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, show_temp_max,
        set_temp_max, 0);
static SENSOR_DEVICE_ATTR(temp2_max, S_IWUSR | S_IRUGO, show_temp_max,
        set_temp_max, 1);
static SENSOR_DEVICE_ATTR(temp1_crit, S_IWUSR | S_IRUGO, show_temp_crit,
        set_temp_crit, 0);
static SENSOR_DEVICE_ATTR(temp2_crit, S_IWUSR | S_IRUGO, show_temp_crit,
        set_temp_crit, 1);
static SENSOR_DEVICE_ATTR(temp1_emergency, S_IWUSR | S_IRUGO,
        show_temp_emergency, set_temp_emergency, 0);
static SENSOR_DEVICE_ATTR(temp2_emergency, S_IWUSR | S_IRUGO,
        show_temp_emergency, set_temp_emergency, 1);
static SENSOR_DEVICE_ATTR(pwm1, S_IWUSR | S_IRUGO, show_pwm, set_pwm, 0);
static SENSOR_DEVICE_ATTR(pwm2, S_IWUSR | S_IRUGO, show_pwm, set_pwm, 1);
static SENSOR_DEVICE_ATTR(fan1_input, S_IRUGO, show_fan_input, NULL, 0);
static SENSOR_DEVICE_ATTR(fan2_input, S_IRUGO, show_fan_input, NULL, 1);
static SENSOR_DEVICE_ATTR(fan1_fault, S_IRUGO, show_alarm, NULL, 1);
static SENSOR_DEVICE_ATTR(fan2_fault, S_IRUGO, show_alarm, NULL, 0);
static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL, 3);
static SENSOR_DEVICE_ATTR(temp2_max_alarm, S_IRUGO, show_alarm, NULL, 2);
static SENSOR_DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL, 7);
static SENSOR_DEVICE_ATTR(temp2_crit_alarm, S_IRUGO, show_alarm, NULL, 6);
static SENSOR_DEVICE_ATTR(temp1_emergency_alarm, S_IRUGO, show_alarm, NULL, 5);
static SENSOR_DEVICE_ATTR(temp2_emergency_alarm, S_IRUGO, show_alarm, NULL, 4);


static struct attribute *max6639_attributes[] = {
    &sensor_dev_attr_temp1_input.dev_attr.attr,
    &sensor_dev_attr_temp2_input.dev_attr.attr,
    &sensor_dev_attr_temp1_fault.dev_attr.attr,
    &sensor_dev_attr_temp2_fault.dev_attr.attr,
    &sensor_dev_attr_temp1_max.dev_attr.attr,
    &sensor_dev_attr_temp2_max.dev_attr.attr,
    &sensor_dev_attr_temp1_crit.dev_attr.attr,
    &sensor_dev_attr_temp2_crit.dev_attr.attr,
    &sensor_dev_attr_temp1_emergency.dev_attr.attr,
    &sensor_dev_attr_temp2_emergency.dev_attr.attr,
    &sensor_dev_attr_pwm1.dev_attr.attr,
    &sensor_dev_attr_pwm2.dev_attr.attr,
    &sensor_dev_attr_fan1_input.dev_attr.attr,
    &sensor_dev_attr_fan2_input.dev_attr.attr,
    &sensor_dev_attr_fan1_fault.dev_attr.attr,
    &sensor_dev_attr_fan2_fault.dev_attr.attr,
    &sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
    &sensor_dev_attr_temp2_max_alarm.dev_attr.attr,
    &sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
    &sensor_dev_attr_temp2_crit_alarm.dev_attr.attr,
    &sensor_dev_attr_temp1_emergency_alarm.dev_attr.attr,
    &sensor_dev_attr_temp2_emergency_alarm.dev_attr.attr,
    NULL
};

static const struct attribute_group max6639_group = {
    .attrs = max6639_attributes,
};

/*
 *  returns respective index in rpm_ranges table
 *  1 by default on invalid range
 */
static int rpm_range_to_reg(int range)
{
    int i;

    for (i = 0; i < ARRAY_SIZE(rpm_ranges); i++) {
        if (rpm_ranges[i] == range)
            return i;
    }

    return 1; /* default: 4000 RPM */
}

static int max6639_init_client(struct i2c_client *client)
{
    struct max6639_data *data = i2c_get_clientdata(client);
    struct max6639_platform_data *max6639_info =
        client->dev.platform_data;
    int i = 0;
    int rpm_range = 1; /* default: 4000 RPM */
    int err = 0;

    /* Reset chip to default values, see below for GCONFIG setup */
    err = i2c_smbus_write_byte_data(client, MAX6639_REG_GCONFIG,
                  MAX6639_GCONFIG_POR);
    if (err)
        goto exit;

    /* Fans pulse per revolution is 2 by default */
    if (max6639_info && max6639_info->ppr > 0 &&
            max6639_info->ppr < 5)
        data->ppr = max6639_info->ppr;
    else
        data->ppr = 2;
    data->ppr -= 1;
    err = i2c_smbus_write_byte_data(client,
            MAX6639_REG_FAN_PPR(i),
            data->ppr << 5);
    if (err)
        goto exit;

    if (max6639_info)
        rpm_range = rpm_range_to_reg(max6639_info->rpm_range);
    data->rpm_range = rpm_range;

    for (i = 0; i < 2; i++) {

        /* Fans config PWM, RPM */
        err = i2c_smbus_write_byte_data(client,
            MAX6639_REG_FAN_CONFIG1(i),
            MAX6639_FAN_CONFIG1_PWM | rpm_range);
        if (err)
            goto exit;

        /* Fans PWM polarity high by default */
        if (max6639_info && max6639_info->pwm_polarity == 0)
            err = i2c_smbus_write_byte_data(client,
                MAX6639_REG_FAN_CONFIG2a(i), 0x00);
        else
            err = i2c_smbus_write_byte_data(client,
                MAX6639_REG_FAN_CONFIG2a(i), 0x02);
        if (err)
            goto exit;

        /*
         * /THERM full speed enable,
         * PWM frequency 25kHz, see also GCONFIG below
         */
        err = i2c_smbus_write_byte_data(client,
            MAX6639_REG_FAN_CONFIG3(i),
            MAX6639_FAN_CONFIG3_THERM_FULL_SPEED | 0x03);
        if (err)
            goto exit;

        /* Max. temp. 80C/90C/100C */
        data->temp_therm[i] = 80;
        data->temp_alert[i] = 90;
        data->temp_ot[i] = 100;
        err = i2c_smbus_write_byte_data(client,
                MAX6639_REG_THERM_LIMIT(i),
                data->temp_therm[i]);
        if (err)
            goto exit;
        err = i2c_smbus_write_byte_data(client,
                MAX6639_REG_ALERT_LIMIT(i),
                data->temp_alert[i]);
        if (err)
            goto exit;
        err = i2c_smbus_write_byte_data(client,
                MAX6639_REG_OT_LIMIT(i), data->temp_ot[i]);
        if (err)
            goto exit;

        /* PWM 120/120 (i.e. 100%) */
        data->pwm[i] = 120;
        err = i2c_smbus_write_byte_data(client,
                MAX6639_REG_TARGTDUTY(i), data->pwm[i]);
        if (err)
            goto exit;
    }
    /* Start monitoring */
    err = i2c_smbus_write_byte_data(client, MAX6639_REG_GCONFIG,
        MAX6639_GCONFIG_DISABLE_TIMEOUT | MAX6639_GCONFIG_CH2_LOCAL |
        MAX6639_GCONFIG_PWM_FREQ_HI);
exit:
    return err;
}

/* Return 0 if detection is successful, -ENODEV otherwise */
static int max6639_detect(struct i2c_client *client,
              struct i2c_board_info *info)
{
    struct i2c_adapter *adapter = client->adapter;
    int dev_id, manu_id;

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

    /* Actual detection via device and manufacturer ID */
    dev_id = i2c_smbus_read_byte_data(client, MAX6639_REG_DEVID);
    manu_id = i2c_smbus_read_byte_data(client, MAX6639_REG_MANUID);
    if (dev_id != 0x58 || manu_id != 0x4D)
        return -ENODEV;

    strlcpy(info->type, "max6639", I2C_NAME_SIZE);

    return 0;
}

static int max6639_probe(struct i2c_client *client,
             const struct i2c_device_id *id)
{
    struct max6639_data *data;
    int err;

    data = kzalloc(sizeof(struct max6639_data), GFP_KERNEL);
    if (!data) {
        err = -ENOMEM;
        goto exit;
    }

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

    /* Initialize the max6639 chip */
    err = max6639_init_client(client);
    if (err < 0)
        goto error_free;

    /* Register sysfs hooks */
    err = sysfs_create_group(&client->dev.kobj, &max6639_group);
    if (err)
        goto error_free;

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

    dev_info(&client->dev, "temperature sensor and fan control found\n");

    return 0;

error_remove:
    sysfs_remove_group(&client->dev.kobj, &max6639_group);
error_free:
    kfree(data);
exit:
    return err;
}

static int max6639_remove(struct i2c_client *client)
{
    struct max6639_data *data = i2c_get_clientdata(client);

    hwmon_device_unregister(data->hwmon_dev);
    sysfs_remove_group(&client->dev.kobj, &max6639_group);

    kfree(data);
    return 0;
}

static int max6639_suspend(struct i2c_client *client, pm_message_t mesg)
{
    int data = i2c_smbus_read_byte_data(client, MAX6639_REG_GCONFIG);
    if (data < 0)
        return data;

    return i2c_smbus_write_byte_data(client,
            MAX6639_REG_GCONFIG, data | MAX6639_GCONFIG_STANDBY);
}

static int max6639_resume(struct i2c_client *client)
{
    int data = i2c_smbus_read_byte_data(client, MAX6639_REG_GCONFIG);
    if (data < 0)
        return data;

    return i2c_smbus_write_byte_data(client,
            MAX6639_REG_GCONFIG, data & ~MAX6639_GCONFIG_STANDBY);
}

static const struct i2c_device_id max6639_id[] = {
    {"max6639", 0},
    { }
};

MODULE_DEVICE_TABLE(i2c, max6639_id);

static struct i2c_driver max6639_driver = {
    .class = I2C_CLASS_HWMON,
    .driver = {
           .name = "max6639",
           },
    .probe = max6639_probe,
    .remove = max6639_remove,
    .suspend = max6639_suspend,
    .resume = max6639_resume,
    .id_table = max6639_id,
    .detect = max6639_detect,
    .address_list = normal_i2c,
};

static int __init max6639_module_init(void)
{
    return i2c_add_driver(&max6639_driver);
}

static void __exit max6639_module_exit(void)
{
    i2c_del_driver(&max6639_driver);
}

MODULE_AUTHOR("Roland Stigge <[email protected]>");
MODULE_DESCRIPTION("max6639 driver");
MODULE_LICENSE("GPL");

module_init(max6639_module_init);
module_exit(max6639_module_exit);