backlight: backlight: Document enums in backlight.h

#include <linux/mutex.h>

#include <linux/notifier.h>

/**

 * enum backlight_update_reason - what method was used to update backlight

 *

 * A driver indicates the method (reason) used for updating the backlight

 * when calling backlight_force_update().

 */

enum backlight_update_reason {

	/**

	 * @BACKLIGHT_UPDATE_HOTKEY: The backlight was updated using a hot-key.

	 */

	BACKLIGHT_UPDATE_HOTKEY,

	/**

	 * @BACKLIGHT_UPDATE_SYSFS: The backlight was updated using sysfs.

	 */

	BACKLIGHT_UPDATE_SYSFS,

};

/**

 * enum backlight_type - the type of backlight control

 *

 * The type of interface used to control the backlight.

 */

enum backlight_type {

	/**

	 * @BACKLIGHT_RAW:

	 *

	 * The backlight is controlled using hardware registers.

	 */

	BACKLIGHT_RAW = 1,

	/**

	 * @BACKLIGHT_PLATFORM:

	 *

	 * The backlight is controlled using a platform-specific interface.

	 */

	BACKLIGHT_PLATFORM,

	/**

	 * @BACKLIGHT_FIRMWARE:

	 *

	 * The backlight is controlled using a standard firmware interface.

	 */

	BACKLIGHT_FIRMWARE,

	/**

	 * @BACKLIGHT_TYPE_MAX: Number of entries.

	 */

	BACKLIGHT_TYPE_MAX,

};

/**

 * enum backlight_notification - the type of notification

 *

 * The notifications that is used for notification sent to the receiver

 * that registered notifications using backlight_register_notifier().

 */

enum backlight_notification {

	/**

	 * @BACKLIGHT_REGISTERED: The backlight device is registered.

	 */

	BACKLIGHT_REGISTERED,

	/**

	 * @BACKLIGHT_UNREGISTERED: The backlight revice is unregistered.

	 */

	BACKLIGHT_UNREGISTERED,

};

/** enum backlight_scale - the type of scale used for brightness values

 *

 * The type of scale used for brightness values.

 */

enum backlight_scale {

	/**

	 * @BACKLIGHT_SCALE_UNKNOWN: The scale is unknown.

	 */

	BACKLIGHT_SCALE_UNKNOWN = 0,

	/**

	 * @BACKLIGHT_SCALE_LINEAR: The scale is linear.

	 *

	 * The linear scale will increase brightness the same for each step.

	 */

	BACKLIGHT_SCALE_LINEAR,

	/**

	 * @BACKLIGHT_SCALE_NON_LINEAR: The scale is not linear.

	 *

	 * This is often used when the brightness values tries to adjust to

	 * the relative perception of the eye demanding a non-linear scale.

	 */

	BACKLIGHT_SCALE_NON_LINEAR,

};