hwmon: (f75375s) Fix writes to the pwm* attribute for the F75387

For the F75387, the register holding the current PWM duty cycle value is
r/o; changing it requires writing to the fan expect register instead.

Signed-off-by: Nikolaus Schulz <mail@microschulz.de>
[guenter.roeck@ericsson.com: Simplified function parameters]
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>

drivers/hwmon/f75375s.c

@@ -178,6 +178,16 @@ static inline void f75375_write16(struct i2c_client *client, u8 reg,
 	i2c_smbus_write_byte_data(client, reg + 1, (value & 0xFF));
 }
 
+static void f75375_write_pwm(struct i2c_client *client, int nr)
+{
+	struct f75375_data *data = i2c_get_clientdata(client);
+	if (data->kind == f75387)
+		f75375_write16(client, F75375_REG_FAN_EXP(nr), data->pwm[nr]);
+	else
+		f75375_write8(client, F75375_REG_FAN_PWM_DUTY(nr),
+			      data->pwm[nr]);
+}
+
 static struct f75375_data *f75375_update_device(struct device *dev)
 {
 	struct i2c_client *client = to_i2c_client(dev);
@@ -309,7 +319,7 @@ static ssize_t set_pwm(struct device *dev, struct device_attribute *attr,
 
 	mutex_lock(&data->update_lock);
 	data->pwm[nr] = SENSORS_LIMIT(val, 0, 255);
-	f75375_write8(client, F75375_REG_FAN_PWM_DUTY(nr), data->pwm[nr]);
+	f75375_write_pwm(client, nr);
 	mutex_unlock(&data->update_lock);
 	return count;
 }
@@ -374,8 +384,7 @@ static int set_pwm_enable_direct(struct i2c_client *client, int nr, int val)
 	f75375_write8(client, F75375_REG_FAN_TIMER, fanmode);
 	data->pwm_enable[nr] = val;
 	if (val == 0)
-		f75375_write8(client, F75375_REG_FAN_PWM_DUTY(nr),
-				data->pwm[nr]);
+		f75375_write_pwm(client, nr);
 	return 0;
 }
 
@@ -759,8 +768,7 @@ static void f75375_init(struct i2c_client *client, struct f75375_data *data,
 	set_pwm_enable_direct(client, 1, f75375s_pdata->pwm_enable[1]);
 	for (nr = 0; nr < 2; nr++) {
 		data->pwm[nr] = SENSORS_LIMIT(f75375s_pdata->pwm[nr], 0, 255);
-		f75375_write8(client, F75375_REG_FAN_PWM_DUTY(nr),
-			data->pwm[nr]);
+		f75375_write_pwm(client, nr);
 	}
 
 }