[mirror_ubuntu-artful-kernel.git] / include / linux / backlight.h

/*
 * Backlight Lowlevel Control Abstraction
 *
 * Copyright (C) 2003,2004 Hewlett-Packard Company
 *
 */

#ifndef _LINUX_BACKLIGHT_H
#define _LINUX_BACKLIGHT_H

#include <linux/device.h>
#include <linux/mutex.h>
#include <linux/notifier.h>

/* Notes on locking:
 *
 * backlight_device->ops_lock is an internal backlight lock protecting the
 * ops pointer and no code outside the core should need to touch it.
 *
 * Access to update_status() is serialised by the update_lock mutex since
 * most drivers seem to need this and historically get it wrong.
 *
 * Most drivers don't need locking on their get_brightness() method.
 * If yours does, you need to implement it in the driver. You can use the
 * update_lock mutex if appropriate.
 *
 * Any other use of the locks below is probably wrong.
 */

struct backlight_device;
struct fb_info;

struct backlight_ops {
	/* Notify the backlight driver some property has changed */
	int (*update_status)(struct backlight_device *);
	/* Return the current backlight brightness (accounting for power,
	   fb_blank etc.) */
	int (*get_brightness)(struct backlight_device *);
	/* Check if given framebuffer device is the one bound to this backlight;
	   return 0 if not, !=0 if it is. If NULL, backlight always matches the fb. */
	int (*check_fb)(struct fb_info *);
};

/* This structure defines all the properties of a backlight */
struct backlight_properties {
	/* Current User requested brightness (0 - max_brightness) */
	int brightness;
	/* Maximal value for brightness (read-only) */
	int max_brightness;
	/* Current FB Power mode (0: full on, 1..3: power saving
	   modes; 4: full off), see FB_BLANK_XXX */
	int power;
	/* FB Blanking active? (values as for power) */
	int fb_blank;
};

struct backlight_device {
	/* Backlight properties */
	struct backlight_properties props;

	/* Serialise access to update_status method */
	struct mutex update_lock;

	/* This protects the 'ops' field. If 'ops' is NULL, the driver that
	   registered this device has been unloaded, and if class_get_devdata()
	   points to something in the body of that driver, it is also invalid. */
	struct mutex ops_lock;
	struct backlight_ops *ops;

	/* The framebuffer notifier block */
	struct notifier_block fb_notif;
	/* The class device structure */
	struct class_device class_dev;
};

static inline void backlight_update_status(struct backlight_device *bd)
{
	mutex_lock(&bd->update_lock);
	if (bd->ops && bd->ops->update_status)
		bd->ops->update_status(bd);
	mutex_unlock(&bd->update_lock);
}

extern struct backlight_device *backlight_device_register(const char *name,
	struct device *dev, void *devdata, struct backlight_ops *ops);
extern void backlight_device_unregister(struct backlight_device *bd);

#define to_backlight_device(obj) container_of(obj, struct backlight_device, class_dev)

#endif
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Backlight Lowlevel Control Abstraction
	3	*
	4	* Copyright (C) 2003,2004 Hewlett-Packard Company
	5	*
	6	*/
	7
	8	#ifndef _LINUX_BACKLIGHT_H
	9	#define _LINUX_BACKLIGHT_H
	10
	11	#include <linux/device.h>
28ee086d	12	#include <linux/mutex.h>
1da177e4 LT	13	#include <linux/notifier.h>
1da177e4 LT	14
28ee086d RP	15	/* Notes on locking:
28ee086d RP	16	*
599a52d1 RP	17	* backlight_device->ops_lock is an internal backlight lock protecting the
599a52d1 RP	18	* ops pointer and no code outside the core should need to touch it.
28ee086d RP	19	*
	20	* Access to update_status() is serialised by the update_lock mutex since
	21	* most drivers seem to need this and historically get it wrong.
	22	*
	23	* Most drivers don't need locking on their get_brightness() method.
	24	* If yours does, you need to implement it in the driver. You can use the
	25	* update_lock mutex if appropriate.
	26	*
	27	* Any other use of the locks below is probably wrong.
	28	*/
	29
1da177e4 LT	30	struct backlight_device;
	31	struct fb_info;
	32
599a52d1	33	struct backlight_ops {
6ca01765 RP	34	/* Notify the backlight driver some property has changed */
	35	int (update_status)(struct backlight_device );
	36	/* Return the current backlight brightness (accounting for power,
	37	fb_blank etc.) */
1da177e4	38	int (get_brightness)(struct backlight_device );
1da177e4 LT	39	/* Check if given framebuffer device is the one bound to this backlight;
	40	return 0 if not, !=0 if it is. If NULL, backlight always matches the fb. */
	41	int (check_fb)(struct fb_info );
599a52d1	42	};
6ca01765	43
599a52d1 RP	44	/* This structure defines all the properties of a backlight */
599a52d1 RP	45	struct backlight_properties {
6ca01765 RP	46	/* Current User requested brightness (0 - max_brightness) */
	47	int brightness;
	48	/* Maximal value for brightness (read-only) */
	49	int max_brightness;
	50	/* Current FB Power mode (0: full on, 1..3: power saving
	51	modes; 4: full off), see FB_BLANK_XXX */
	52	int power;
	53	/* FB Blanking active? (values as for power) */
	54	int fb_blank;
1da177e4 LT	55	};
	56
	57	struct backlight_device {
599a52d1 RP	58	/* Backlight properties */
	59	struct backlight_properties props;
	60
28ee086d RP	61	/* Serialise access to update_status method */
28ee086d RP	62	struct mutex update_lock;
599a52d1 RP	63
	64	/* This protects the 'ops' field. If 'ops' is NULL, the driver that
	65	registered this device has been unloaded, and if class_get_devdata()
	66	points to something in the body of that driver, it is also invalid. */
	67	struct mutex ops_lock;
	68	struct backlight_ops *ops;
	69
1da177e4 LT	70	/* The framebuffer notifier block */
	71	struct notifier_block fb_notif;
	72	/* The class device structure */
	73	struct class_device class_dev;
	74	};
	75
28ee086d RP	76	static inline void backlight_update_status(struct backlight_device *bd)
	77	{
	78	mutex_lock(&bd->update_lock);
599a52d1 RP	79	if (bd->ops && bd->ops->update_status)
599a52d1 RP	80	bd->ops->update_status(bd);
28ee086d RP	81	mutex_unlock(&bd->update_lock);
	82	}
	83
1da177e4	84	extern struct backlight_device backlight_device_register(const char name,
599a52d1	85	struct device dev, void devdata, struct backlight_ops *ops);
1da177e4 LT	86	extern void backlight_device_unregister(struct backlight_device *bd);
	87
	88	#define to_backlight_device(obj) container_of(obj, struct backlight_device, class_dev)
	89
	90	#endif