hwmon: (gpio-fan) Add a shutdown handler to poweroff the fans

Poweroff the fans when shutting down the system. Else,
echo '1' > /sys/class/hwmon/hwmon0/fan1_target; poweroff leaves the
fan running if the System power off does not drive the gpio expander
which might control the fan power supply.
Signed-off-by: NNishanth Menon <nm@ti.com>
Signed-off-by: NGuenter Roeck <linux@roeck-us.net>

drivers/hwmon/gpio-fan.c

@@ -550,6 +550,14 @@ static int gpio_fan_probe(struct platform_device *pdev)
 	return 0;
 }
 
+static void gpio_fan_shutdown(struct platform_device *pdev)
+{
+	struct gpio_fan_data *fan_data = dev_get_drvdata(&pdev->dev);
+
+	if (fan_data->ctrl)
+		set_fan_speed(fan_data, 0);
+}
+
 #ifdef CONFIG_PM_SLEEP
 static int gpio_fan_suspend(struct device *dev)
 {
@@ -581,6 +589,7 @@ static SIMPLE_DEV_PM_OPS(gpio_fan_pm, gpio_fan_suspend, gpio_fan_resume);
 
 static struct platform_driver gpio_fan_driver = {
 	.probe		= gpio_fan_probe,
+	.shutdown	= gpio_fan_shutdown,
 	.driver	= {
 		.name	= "gpio-fan",
 		.pm	= GPIO_FAN_PM,