// SPDX-License-Identifier: GPL-2.0-only
/*
 * w83l786ng.c - Linux kernel driver for hardware monitoring
 * Copyright (c) 2007 Kevin Lo <kevlo@kevlo.org>
 */

/*
 * Supports following chips:
 *
 * Chip         #vin    #fanin  #pwm    #temp   wchipid vendid  i2c     ISA
 * w83l786ng    3       2       2       2       0x7b    0x5ca3  yes     no
 */

#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>

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

/* Insmod parameters */

static bool reset;
module_param(reset, bool, 0);
MODULE_PARM_DESC(reset, "Set to 1 to reset chip, not recommended");

#define W83L786NG_REG_IN_MIN(nr)        (0x2C + (nr) * 2)
#define W83L786NG_REG_IN_MAX(nr)        (0x2B + (nr) * 2)
#define W83L786NG_REG_IN(nr)            ((nr) + 0x20)

#define W83L786NG_REG_FAN(nr)           ((nr) + 0x28)
#define W83L786NG_REG_FAN_MIN(nr)       ((nr) + 0x3B)

#define W83L786NG_REG_CONFIG            0x40
#define W83L786NG_REG_ALARM1            0x41
#define W83L786NG_REG_ALARM2            0x42
#define W83L786NG_REG_GPIO_EN           0x47
#define W83L786NG_REG_MAN_ID2           0x4C
#define W83L786NG_REG_MAN_ID1           0x4D
#define W83L786NG_REG_CHIP_ID           0x4E

#define W83L786NG_REG_DIODE             0x53
#define W83L786NG_REG_FAN_DIV           0x54
#define W83L786NG_REG_FAN_CFG           0x80

#define W83L786NG_REG_TOLERANCE         0x8D

static const u8 W83L786NG_REG_TEMP[2][3] = {
        { 0x25,         /* TEMP 0 in DataSheet */
          0x35,         /* TEMP 0 Over in DataSheet */
          0x36 },       /* TEMP 0 Hyst in DataSheet */
        { 0x26,         /* TEMP 1 in DataSheet */
          0x37,         /* TEMP 1 Over in DataSheet */
          0x38 }        /* TEMP 1 Hyst in DataSheet */
};

static const u8 W83L786NG_PWM_MODE_SHIFT[] = {6, 7};
static const u8 W83L786NG_PWM_ENABLE_SHIFT[] = {2, 4};

/* FAN Duty Cycle, be used to control */
static const u8 W83L786NG_REG_PWM[] = {0x81, 0x87};


static inline u8
FAN_TO_REG(long rpm, int div)
{
        if (rpm == 0)
                return 255;
        rpm = clamp_val(rpm, 1, 1000000);
        return clamp_val((1350000 + rpm * div / 2) / (rpm * div), 1, 254);
}

static int fan_from_reg(int val, int div)
{
        if (val == 0)
                return -1;
        if (val == 255)
                return 0;
        return 1350000 / (val * div);
}

/* for temp */
#define TEMP_TO_REG(val)        (clamp_val(((val) < 0 ? (val) + 0x100 * 1000 \
                                                      : (val)) / 1000, 0, 0xff))

static int temp_from_reg(int val)
{
        if (val & 0x80)
                return (val - 0x100) * 1000;
        return val * 1000;
}

/*
 * The analog voltage inputs have 8mV LSB. Since the sysfs output is
 * in mV as would be measured on the chip input pin, need to just
 * multiply/divide by 8 to translate from/to register values.
 */
#define IN_TO_REG(val)          (clamp_val((((val) + 4) / 8), 0, 255))
#define IN_FROM_REG(val)        ((val) * 8)

#define DIV_FROM_REG(val)       (1 << (val))

static inline u8
DIV_TO_REG(long val)
{
        int i;
        val = clamp_val(val, 1, 128) >> 1;
        for (i = 0; i < 7; i++) {
                if (val == 0)
                        break;
                val >>= 1;
        }
        return (u8)i;
}

struct w83l786ng_data {
        struct i2c_client *client;
        struct mutex update_lock;
        bool valid;                     /* true if following fields are valid */
        unsigned long last_updated;     /* In jiffies */
        unsigned long last_nonvolatile; /* In jiffies, last time we update the
                                         * nonvolatile registers */

        u8 in[3];
        u8 in_max[3];
        u8 in_min[3];
        u8 fan[2];
        u8 fan_div[2];
        u8 fan_min[2];
        u8 temp_type[2];
        u8 temp[2][3];
        u8 pwm[2];
        u8 pwm_mode[2]; /* 0->DC variable voltage
                         * 1->PWM variable duty cycle */

        u8 pwm_enable[2]; /* 1->manual
                           * 2->thermal cruise (also called SmartFan I) */
        u8 tolerance[2];
};

static u8
w83l786ng_read_value(struct i2c_client *client, u8 reg)
{
        return i2c_smbus_read_byte_data(client, reg);
}

static int
w83l786ng_write_value(struct i2c_client *client, u8 reg, u8 value)
{
        return i2c_smbus_write_byte_data(client, reg, value);
}

static struct w83l786ng_data *w83l786ng_update_device(struct device *dev)
{
        struct w83l786ng_data *data = dev_get_drvdata(dev);
        struct i2c_client *client = data->client;
        int i, j;
        u8 reg_tmp, pwmcfg;

        mutex_lock(&data->update_lock);
        if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
            || !data->valid) {
                dev_dbg(&client->dev, "Updating w83l786ng data.\n");

                /* Update the voltages measured value and limits */
                for (i = 0; i < 3; i++) {
                        data->in[i] = w83l786ng_read_value(client,
                            W83L786NG_REG_IN(i));
                        data->in_min[i] = w83l786ng_read_value(client,
                            W83L786NG_REG_IN_MIN(i));
                        data->in_max[i] = w83l786ng_read_value(client,
                            W83L786NG_REG_IN_MAX(i));
                }

                /* Update the fan counts and limits */
                for (i = 0; i < 2; i++) {
                        data->fan[i] = w83l786ng_read_value(client,
                            W83L786NG_REG_FAN(i));
                        data->fan_min[i] = w83l786ng_read_value(client,
                            W83L786NG_REG_FAN_MIN(i));
                }

                /* Update the fan divisor */
                reg_tmp = w83l786ng_read_value(client, W83L786NG_REG_FAN_DIV);
                data->fan_div[0] = reg_tmp & 0x07;
                data->fan_div[1] = (reg_tmp >> 4) & 0x07;

                pwmcfg = w83l786ng_read_value(client, W83L786NG_REG_FAN_CFG);
                for (i = 0; i < 2; i++) {
                        data->pwm_mode[i] =
                            ((pwmcfg >> W83L786NG_PWM_MODE_SHIFT[i]) & 1)
                            ? 0 : 1;
                        data->pwm_enable[i] =
                            ((pwmcfg >> W83L786NG_PWM_ENABLE_SHIFT[i]) & 3) + 1;
                        data->pwm[i] =
                            (w83l786ng_read_value(client, W83L786NG_REG_PWM[i])
                             & 0x0f) * 0x11;
                }


                /* Update the temperature sensors */
                for (i = 0; i < 2; i++) {
                        for (j = 0; j < 3; j++) {
                                data->temp[i][j] = w83l786ng_read_value(client,
                                    W83L786NG_REG_TEMP[i][j]);
                        }
                }

                /* Update Smart Fan I/II tolerance */
                reg_tmp = w83l786ng_read_value(client, W83L786NG_REG_TOLERANCE);
                data->tolerance[0] = reg_tmp & 0x0f;
                data->tolerance[1] = (reg_tmp >> 4) & 0x0f;

                data->last_updated = jiffies;
                data->valid = true;

        }

        mutex_unlock(&data->update_lock);

        return data;
}

/* following are the sysfs callback functions */
#define show_in_reg(reg) \
static ssize_t \
show_##reg(struct device *dev, struct device_attribute *attr, \
           char *buf) \
{ \
        int nr = to_sensor_dev_attr(attr)->index; \
        struct w83l786ng_data *data = w83l786ng_update_device(dev); \
        return sprintf(buf, "%d\n", IN_FROM_REG(data->reg[nr])); \
}

show_in_reg(in)
show_in_reg(in_min)
show_in_reg(in_max)

#define store_in_reg(REG, reg) \
static ssize_t \
store_in_##reg(struct device *dev, struct device_attribute *attr, \
               const char *buf, size_t count) \
{ \
        int nr = to_sensor_dev_attr(attr)->index; \
        struct w83l786ng_data *data = dev_get_drvdata(dev); \
        struct i2c_client *client = data->client; \
        unsigned long val; \
        int err = kstrtoul(buf, 10, &val); \
        if (err) \
                return err; \
        mutex_lock(&data->update_lock); \
        data->in_##reg[nr] = IN_TO_REG(val); \
        w83l786ng_write_value(client, W83L786NG_REG_IN_##REG(nr), \
                              data->in_##reg[nr]); \
        mutex_unlock(&data->update_lock); \
        return count; \
}

store_in_reg(MIN, min)
store_in_reg(MAX, max)

static struct sensor_device_attribute sda_in_input[] = {
        SENSOR_ATTR(in0_input, S_IRUGO, show_in, NULL, 0),
        SENSOR_ATTR(in1_input, S_IRUGO, show_in, NULL, 1),
        SENSOR_ATTR(in2_input, S_IRUGO, show_in, NULL, 2),
};

static struct sensor_device_attribute sda_in_min[] = {
        SENSOR_ATTR(in0_min, S_IWUSR | S_IRUGO, show_in_min, store_in_min, 0),
        SENSOR_ATTR(in1_min, S_IWUSR | S_IRUGO, show_in_min, store_in_min, 1),
        SENSOR_ATTR(in2_min, S_IWUSR | S_IRUGO, show_in_min, store_in_min, 2),
};

static struct sensor_device_attribute sda_in_max[] = {
        SENSOR_ATTR(in0_max, S_IWUSR | S_IRUGO, show_in_max, store_in_max, 0),
        SENSOR_ATTR(in1_max, S_IWUSR | S_IRUGO, show_in_max, store_in_max, 1),
        SENSOR_ATTR(in2_max, S_IWUSR | S_IRUGO, show_in_max, store_in_max, 2),
};

#define show_fan_reg(reg) \
static ssize_t show_##reg(struct device *dev, struct device_attribute *attr, \
                          char *buf) \
{ \
        int nr = to_sensor_dev_attr(attr)->index; \
        struct w83l786ng_data *data = w83l786ng_update_device(dev); \
        return sprintf(buf, "%d\n", \
                fan_from_reg(data->reg[nr], DIV_FROM_REG(data->fan_div[nr]))); \
}

show_fan_reg(fan);
show_fan_reg(fan_min);

static ssize_t
store_fan_min(struct device *dev, struct device_attribute *attr,
              const char *buf, size_t count)
{
        int nr = to_sensor_dev_attr(attr)->index;
        struct w83l786ng_data *data = dev_get_drvdata(dev);
        struct i2c_client *client = data->client;
        unsigned long val;
        int err;

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

        mutex_lock(&data->update_lock);
        data->fan_min[nr] = FAN_TO_REG(val, DIV_FROM_REG(data->fan_div[nr]));
        w83l786ng_write_value(client, W83L786NG_REG_FAN_MIN(nr),
                              data->fan_min[nr]);
        mutex_unlock(&data->update_lock);

        return count;
}

static ssize_t
show_fan_div(struct device *dev, struct device_attribute *attr,
             char *buf)
{
        int nr = to_sensor_dev_attr(attr)->index;
        struct w83l786ng_data *data = w83l786ng_update_device(dev);
        return sprintf(buf, "%u\n", DIV_FROM_REG(data->fan_div[nr]));
}

/*
 * Note: we save and restore the fan minimum here, because its value is
 * determined in part by the fan divisor.  This follows the principle of
 * least surprise; the user doesn't expect the fan minimum to change just
 * because the divisor changed.
 */
static ssize_t
store_fan_div(struct device *dev, struct device_attribute *attr,
              const char *buf, size_t count)
{
        int nr = to_sensor_dev_attr(attr)->index;
        struct w83l786ng_data *data = dev_get_drvdata(dev);
        struct i2c_client *client = data->client;

        unsigned long min;
        u8 tmp_fan_div;
        u8 fan_div_reg;
        u8 keep_mask = 0;
        u8 new_shift = 0;

        unsigned long val;
        int err;

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

        /* Save fan_min */
        mutex_lock(&data->update_lock);
        min = fan_from_reg(data->fan_min[nr], DIV_FROM_REG(data->fan_div[nr]));

        data->fan_div[nr] = DIV_TO_REG(val);

        switch (nr) {
        case 0:
                keep_mask = 0xf8;
                new_shift = 0;
                break;
        case 1:
                keep_mask = 0x8f;
                new_shift = 4;
                break;
        }

        fan_div_reg = w83l786ng_read_value(client, W83L786NG_REG_FAN_DIV)
                                           & keep_mask;

        tmp_fan_div = (data->fan_div[nr] << new_shift) & ~keep_mask;

        w83l786ng_write_value(client, W83L786NG_REG_FAN_DIV,
                              fan_div_reg | tmp_fan_div);

        /* Restore fan_min */
        data->fan_min[nr] = FAN_TO_REG(min, DIV_FROM_REG(data->fan_div[nr]));
        w83l786ng_write_value(client, W83L786NG_REG_FAN_MIN(nr),
                              data->fan_min[nr]);
        mutex_unlock(&data->update_lock);

        return count;
}

static struct sensor_device_attribute sda_fan_input[] = {
        SENSOR_ATTR(fan1_input, S_IRUGO, show_fan, NULL, 0),
        SENSOR_ATTR(fan2_input, S_IRUGO, show_fan, NULL, 1),
};

static struct sensor_device_attribute sda_fan_min[] = {
        SENSOR_ATTR(fan1_min, S_IWUSR | S_IRUGO, show_fan_min,
                    store_fan_min, 0),
        SENSOR_ATTR(fan2_min, S_IWUSR | S_IRUGO, show_fan_min,
                    store_fan_min, 1),
};

static struct sensor_device_attribute sda_fan_div[] = {
        SENSOR_ATTR(fan1_div, S_IWUSR | S_IRUGO, show_fan_div,
                    store_fan_div, 0),
        SENSOR_ATTR(fan2_div, S_IWUSR | S_IRUGO, show_fan_div,
                    store_fan_div, 1),
};


/* read/write the temperature, includes measured value and limits */

static ssize_t
show_temp(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct sensor_device_attribute_2 *sensor_attr =
            to_sensor_dev_attr_2(attr);
        int nr = sensor_attr->nr;
        int index = sensor_attr->index;
        struct w83l786ng_data *data = w83l786ng_update_device(dev);
        return sprintf(buf, "%d\n", temp_from_reg(data->temp[nr][index]));
}

static ssize_t
store_temp(struct device *dev, struct device_attribute *attr,
           const char *buf, size_t count)
{
        struct sensor_device_attribute_2 *sensor_attr =
            to_sensor_dev_attr_2(attr);
        int nr = sensor_attr->nr;
        int index = sensor_attr->index;
        struct w83l786ng_data *data = dev_get_drvdata(dev);
        struct i2c_client *client = data->client;
        long val;
        int err;

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

        mutex_lock(&data->update_lock);
        data->temp[nr][index] = TEMP_TO_REG(val);
        w83l786ng_write_value(client, W83L786NG_REG_TEMP[nr][index],
                              data->temp[nr][index]);
        mutex_unlock(&data->update_lock);

        return count;
}

static struct sensor_device_attribute_2 sda_temp_input[] = {
        SENSOR_ATTR_2(temp1_input, S_IRUGO, show_temp, NULL, 0, 0),
        SENSOR_ATTR_2(temp2_input, S_IRUGO, show_temp, NULL, 1, 0),
};

static struct sensor_device_attribute_2 sda_temp_max[] = {
        SENSOR_ATTR_2(temp1_max, S_IRUGO | S_IWUSR,
                      show_temp, store_temp, 0, 1),
        SENSOR_ATTR_2(temp2_max, S_IRUGO | S_IWUSR,
                      show_temp, store_temp, 1, 1),
};

static struct sensor_device_attribute_2 sda_temp_max_hyst[] = {
        SENSOR_ATTR_2(temp1_max_hyst, S_IRUGO | S_IWUSR,
                      show_temp, store_temp, 0, 2),
        SENSOR_ATTR_2(temp2_max_hyst, S_IRUGO | S_IWUSR,
                      show_temp, store_temp, 1, 2),
};

#define show_pwm_reg(reg) \
static ssize_t show_##reg(struct device *dev, struct device_attribute *attr, \
                          char *buf) \
{ \
        struct w83l786ng_data *data = w83l786ng_update_device(dev); \
        int nr = to_sensor_dev_attr(attr)->index; \
        return sprintf(buf, "%d\n", data->reg[nr]); \
}

show_pwm_reg(pwm_mode)
show_pwm_reg(pwm_enable)
show_pwm_reg(pwm)

static ssize_t
store_pwm_mode(struct device *dev, struct device_attribute *attr,
               const char *buf, size_t count)
{
        int nr = to_sensor_dev_attr(attr)->index;
        struct w83l786ng_data *data = dev_get_drvdata(dev);
        struct i2c_client *client = data->client;
        u8 reg;
        unsigned long val;
        int err;

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

        if (val > 1)
                return -EINVAL;
        mutex_lock(&data->update_lock);
        data->pwm_mode[nr] = val;
        reg = w83l786ng_read_value(client, W83L786NG_REG_FAN_CFG);
        reg &= ~(1 << W83L786NG_PWM_MODE_SHIFT[nr]);
        if (!val)
                reg |= 1 << W83L786NG_PWM_MODE_SHIFT[nr];
        w83l786ng_write_value(client, W83L786NG_REG_FAN_CFG, reg);
        mutex_unlock(&data->update_lock);
        return count;
}

static ssize_t
store_pwm(struct device *dev, struct device_attribute *attr,
          const char *buf, size_t count)
{
        int nr = to_sensor_dev_attr(attr)->index;
        struct w83l786ng_data *data = dev_get_drvdata(dev);
        struct i2c_client *client = data->client;
        unsigned long val;
        int err;

        err = kstrtoul(buf, 10, &val);
        if (err)
                return err;
        val = clamp_val(val, 0, 255);
        val = DIV_ROUND_CLOSEST(val, 0x11);

        mutex_lock(&data->update_lock);
        data->pwm[nr] = val * 0x11;
        val |= w83l786ng_read_value(client, W83L786NG_REG_PWM[nr]) & 0xf0;
        w83l786ng_write_value(client, W83L786NG_REG_PWM[nr], val);
        mutex_unlock(&data->update_lock);
        return count;
}

static ssize_t
store_pwm_enable(struct device *dev, struct device_attribute *attr,
                 const char *buf, size_t count)
{
        int nr = to_sensor_dev_attr(attr)->index;
        struct w83l786ng_data *data = dev_get_drvdata(dev);
        struct i2c_client *client = data->client;
        u8 reg;
        unsigned long val;
        int err;

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

        if (!val || val > 2)  /* only modes 1 and 2 are supported */
                return -EINVAL;

        mutex_lock(&data->update_lock);
        reg = w83l786ng_read_value(client, W83L786NG_REG_FAN_CFG);
        data->pwm_enable[nr] = val;
        reg &= ~(0x03 << W83L786NG_PWM_ENABLE_SHIFT[nr]);
        reg |= (val - 1) << W83L786NG_PWM_ENABLE_SHIFT[nr];
        w83l786ng_write_value(client, W83L786NG_REG_FAN_CFG, reg);
        mutex_unlock(&data->update_lock);
        return count;
}

static struct sensor_device_attribute sda_pwm[] = {
        SENSOR_ATTR(pwm1, S_IWUSR | S_IRUGO, show_pwm, store_pwm, 0),
        SENSOR_ATTR(pwm2, S_IWUSR | S_IRUGO, show_pwm, store_pwm, 1),
};

static struct sensor_device_attribute sda_pwm_mode[] = {
        SENSOR_ATTR(pwm1_mode, S_IWUSR | S_IRUGO, show_pwm_mode,
                    store_pwm_mode, 0),
        SENSOR_ATTR(pwm2_mode, S_IWUSR | S_IRUGO, show_pwm_mode,
                    store_pwm_mode, 1),
};

static struct sensor_device_attribute sda_pwm_enable[] = {
        SENSOR_ATTR(pwm1_enable, S_IWUSR | S_IRUGO, show_pwm_enable,
                    store_pwm_enable, 0),
        SENSOR_ATTR(pwm2_enable, S_IWUSR | S_IRUGO, show_pwm_enable,
                    store_pwm_enable, 1),
};

/* For Smart Fan I/Thermal Cruise and Smart Fan II */
static ssize_t
show_tolerance(struct device *dev, struct device_attribute *attr, char *buf)
{
        int nr = to_sensor_dev_attr(attr)->index;
        struct w83l786ng_data *data = w83l786ng_update_device(dev);
        return sprintf(buf, "%ld\n", (long)data->tolerance[nr]);
}

static ssize_t
store_tolerance(struct device *dev, struct device_attribute *attr,
                const char *buf, size_t count)
{
        int nr = to_sensor_dev_attr(attr)->index;
        struct w83l786ng_data *data = dev_get_drvdata(dev);
        struct i2c_client *client = data->client;
        u8 tol_tmp, tol_mask;
        unsigned long val;
        int err;

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

        mutex_lock(&data->update_lock);
        tol_mask = w83l786ng_read_value(client,
            W83L786NG_REG_TOLERANCE) & ((nr == 1) ? 0x0f : 0xf0);
        tol_tmp = clamp_val(val, 0, 15);
        tol_tmp &= 0x0f;
        data->tolerance[nr] = tol_tmp;
        if (nr == 1)
                tol_tmp <<= 4;

        w83l786ng_write_value(client, W83L786NG_REG_TOLERANCE,
                              tol_mask | tol_tmp);
        mutex_unlock(&data->update_lock);
        return count;
}

static struct sensor_device_attribute sda_tolerance[] = {
        SENSOR_ATTR(pwm1_tolerance, S_IWUSR | S_IRUGO,
                    show_tolerance, store_tolerance, 0),
        SENSOR_ATTR(pwm2_tolerance, S_IWUSR | S_IRUGO,
                    show_tolerance, store_tolerance, 1),
};


#define IN_UNIT_ATTRS(X)        \
        &sda_in_input[X].dev_attr.attr,         \
        &sda_in_min[X].dev_attr.attr,           \
        &sda_in_max[X].dev_attr.attr

#define FAN_UNIT_ATTRS(X)       \
        &sda_fan_input[X].dev_attr.attr,        \
        &sda_fan_min[X].dev_attr.attr,          \
        &sda_fan_div[X].dev_attr.attr

#define TEMP_UNIT_ATTRS(X)      \
        &sda_temp_input[X].dev_attr.attr,       \
        &sda_temp_max[X].dev_attr.attr,         \
        &sda_temp_max_hyst[X].dev_attr.attr

#define PWM_UNIT_ATTRS(X)       \
        &sda_pwm[X].dev_attr.attr,              \
        &sda_pwm_mode[X].dev_attr.attr,         \
        &sda_pwm_enable[X].dev_attr.attr

#define TOLERANCE_UNIT_ATTRS(X) \
        &sda_tolerance[X].dev_attr.attr

static struct attribute *w83l786ng_attrs[] = {
        IN_UNIT_ATTRS(0),
        IN_UNIT_ATTRS(1),
        IN_UNIT_ATTRS(2),
        FAN_UNIT_ATTRS(0),
        FAN_UNIT_ATTRS(1),
        TEMP_UNIT_ATTRS(0),
        TEMP_UNIT_ATTRS(1),
        PWM_UNIT_ATTRS(0),
        PWM_UNIT_ATTRS(1),
        TOLERANCE_UNIT_ATTRS(0),
        TOLERANCE_UNIT_ATTRS(1),
        NULL
};

ATTRIBUTE_GROUPS(w83l786ng);

static int
w83l786ng_detect(struct i2c_client *client, struct i2c_board_info *info)
{
        struct i2c_adapter *adapter = client->adapter;
        u16 man_id;
        u8 chip_id;

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

        /* Detection */
        if ((w83l786ng_read_value(client, W83L786NG_REG_CONFIG) & 0x80)) {
                dev_dbg(&adapter->dev, "W83L786NG detection failed at 0x%02x\n",
                        client->addr);
                return -ENODEV;
        }

        /* Identification */
        man_id = (w83l786ng_read_value(client, W83L786NG_REG_MAN_ID1) << 8) +
                 w83l786ng_read_value(client, W83L786NG_REG_MAN_ID2);
        chip_id = w83l786ng_read_value(client, W83L786NG_REG_CHIP_ID);

        if (man_id != 0x5CA3 ||         /* Winbond */
            chip_id != 0x80) {          /* W83L786NG */
                dev_dbg(&adapter->dev,
                        "Unsupported chip (man_id=0x%04X, chip_id=0x%02X)\n",
                        man_id, chip_id);
                return -ENODEV;
        }

        strscpy(info->type, "w83l786ng", I2C_NAME_SIZE);

        return 0;
}

static void w83l786ng_init_client(struct i2c_client *client)
{
        u8 tmp;

        if (reset)
                w83l786ng_write_value(client, W83L786NG_REG_CONFIG, 0x80);

        /* Start monitoring */
        tmp = w83l786ng_read_value(client, W83L786NG_REG_CONFIG);
        if (!(tmp & 0x01))
                w83l786ng_write_value(client, W83L786NG_REG_CONFIG, tmp | 0x01);
}

static int
w83l786ng_probe(struct i2c_client *client)
{
        struct device *dev = &client->dev;
        struct w83l786ng_data *data;
        struct device *hwmon_dev;
        int i;
        u8 reg_tmp;

        data = devm_kzalloc(dev, sizeof(struct w83l786ng_data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        data->client = client;
        mutex_init(&data->update_lock);

        /* Initialize the chip */
        w83l786ng_init_client(client);

        /* A few vars need to be filled upon startup */
        for (i = 0; i < 2; i++) {
                data->fan_min[i] = w83l786ng_read_value(client,
                    W83L786NG_REG_FAN_MIN(i));
        }

        /* Update the fan divisor */
        reg_tmp = w83l786ng_read_value(client, W83L786NG_REG_FAN_DIV);
        data->fan_div[0] = reg_tmp & 0x07;
        data->fan_div[1] = (reg_tmp >> 4) & 0x07;

        hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
                                                           data,
                                                           w83l786ng_groups);
        return PTR_ERR_OR_ZERO(hwmon_dev);
}

static const struct i2c_device_id w83l786ng_id[] = {
        { "w83l786ng" },
        { }
};
MODULE_DEVICE_TABLE(i2c, w83l786ng_id);

static struct i2c_driver w83l786ng_driver = {
        .class          = I2C_CLASS_HWMON,
        .driver = {
                   .name = "w83l786ng",
        },
        .probe          = w83l786ng_probe,
        .id_table       = w83l786ng_id,
        .detect         = w83l786ng_detect,
        .address_list   = normal_i2c,
};

module_i2c_driver(w83l786ng_driver);

MODULE_AUTHOR("Kevin Lo");
MODULE_DESCRIPTION("w83l786ng driver");
MODULE_LICENSE("GPL");