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>

    12 #include <linux/mutex.h>

    13 #include <linux/notifier.h>

    14 

    15 /* Notes on locking:

    16  *

    17  * backlight_device->ops_lock is an internal backlight lock protecting the

    18  * ops pointer and no code outside the core should need to touch it.

    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 

    30 struct backlight_device;

    31 struct fb_info;

    32 

    33 struct backlight_ops {

    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.) */

    38 	int (*get_brightness)(struct backlight_device *);

    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 *);

    42 };

    43 

    44 /* This structure defines all the properties of a backlight */

    45 struct backlight_properties {

    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;

    55 };

    56 

    57 struct backlight_device {

    58 	/* Backlight properties */

    59 	struct backlight_properties props;

    60 

    61 	/* Serialise access to update_status method */

    62 	struct mutex update_lock;

    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 

    70 	/* The framebuffer notifier block */

    71 	struct notifier_block fb_notif;

    72 

    73 	struct device dev;

    74 };

    75 

    76 static inline void backlight_update_status(struct backlight_device *bd)

    77 {

    78 	mutex_lock(&bd->update_lock);

    79 	if (bd->ops && bd->ops->update_status)

    80 		bd->ops->update_status(bd);

    81 	mutex_unlock(&bd->update_lock);

    82 }

    83 

    84 extern struct backlight_device *backlight_device_register(const char *name,

    85 	struct device *dev, void *devdata, struct backlight_ops *ops);

    86 extern void backlight_device_unregister(struct backlight_device *bd);

    87 

    88 #define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)

    89 

    90 static inline void * bl_get_data(struct backlight_device *bl_dev)

    91 {

    92 	return dev_get_drvdata(&bl_dev->dev);

    93 }

    94 

    95 struct generic_bl_info {

    96 	const char *name;

    97 	int max_intensity;

    98 	int default_intensity;

    99 	int limit_mask;

   100 	void (*set_bl_intensity)(int intensity);

   101 	void (*kick_battery)(void);

   102 };

   103 

   104 #endif