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/*
* 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->sem is an internal backlight lock protecting the props
* field 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;
/* This structure defines all the properties of a backlight
(usually attached to a LCD). */
struct backlight_properties {
/* 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 *);
/* 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 {
/* This protects the 'props' field. If 'props' 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 semaphore sem;
/* If this is NULL, the backing module is unloaded */
struct backlight_properties *props;
/* Serialise access to update_status method */
struct mutex update_lock;
/* 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->props && bd->props->update_status)
bd->props->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_properties *bp);
extern void backlight_device_unregister(struct backlight_device *bd);
#define to_backlight_device(obj) container_of(obj, struct backlight_device, class_dev)
#endif
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