backlight: backlight: Document inline functions in backlight.h

Add documentation for the inline functions in backlight.h
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

include/linux/backlight.h

@@ -268,6 +268,10 @@ struct backlight_device {
 	int use_count;
 };
 
+/**
+ * backlight_update_status - force an update of the backlight device status
+ * @bd: the backlight device
+ */
 static inline int backlight_update_status(struct backlight_device *bd)
 {
 	int ret = -ENOENT;
@@ -361,6 +365,18 @@ extern int backlight_device_set_brightness(struct backlight_device *bd, unsigned
 
 #define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)
 
+/**
+ * bl_get_data - access devdata
+ * @bl_dev: pointer to backlight device
+ *
+ * When a backlight device is registered the driver has the possibility
+ * to supply a void * devdata. bl_get_data() return a pointer to the
+ * devdata.
+ *
+ * RETURNS:
+ *
+ * pointer to devdata stored while registering the backlight device.
+ */
 static inline void * bl_get_data(struct backlight_device *bl_dev)
 {
 	return dev_get_drvdata(&bl_dev->dev);