include/linux/backlight.h

   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 enum backlight_update_reason {
  31         BACKLIGHT_UPDATE_HOTKEY,
  32         BACKLIGHT_UPDATE_SYSFS,
  33 };
  34
  35 struct backlight_device;
  36 struct fb_info;
  37
  38 struct backlight_ops {
  39         const unsigned int options;
  40
  41 #define BL_CORE_SUSPENDRESUME   (1 << 0)
  42
  43         /* Notify the backlight driver some property has changed */
  44         int (* const update_status)(struct backlight_device *);
  45         /* Return the current backlight brightness (accounting for power,
  46            fb_blank etc.) */
  47         int (* const get_brightness)(struct backlight_device *);
  48         /* Check if given framebuffer device is the one bound to this backlight;
  49            return 0 if not, !=0 if it is. If NULL, backlight always matches the fb. */
  50         int (* const check_fb)(struct fb_info *);
  51 };
  52
  53 /* This structure defines all the properties of a backlight */
  54 struct backlight_properties {
  55         /* Current User requested brightness (0 - max_brightness) */
  56         int brightness;
  57         /* Maximal value for brightness (read-only) */
  58         int max_brightness;
  59         /* Current FB Power mode (0: full on, 1..3: power saving
  60            modes; 4: full off), see FB_BLANK_XXX */
  61         int power;
  62         /* FB Blanking active? (values as for power) */
  63         /* Due to be removed, please use (state & BL_CORE_FBBLANK) */
  64         int fb_blank;
  65         /* Flags used to signal drivers of state changes */
  66         /* Upper 4 bits are reserved for driver internal use */
  67         unsigned int state;
  68
  69 #define BL_CORE_SUSPENDED       (1 << 0)        /* backlight is suspended */
  70 #define BL_CORE_FBBLANK         (1 << 1)        /* backlight is under an fb blank event */
  71 #define BL_CORE_DRIVER4         (1 << 28)       /* reserved for driver specific use */
  72 #define BL_CORE_DRIVER3         (1 << 29)       /* reserved for driver specific use */
  73 #define BL_CORE_DRIVER2         (1 << 30)       /* reserved for driver specific use */
  74 #define BL_CORE_DRIVER1         (1 << 31)       /* reserved for driver specific use */
  75
  76 };
  77
  78 struct backlight_device {
  79         /* Backlight properties */
  80         struct backlight_properties props;
  81
  82         /* Serialise access to update_status method */
  83         struct mutex update_lock;
  84
  85         /* This protects the 'ops' field. If 'ops' is NULL, the driver that
  86            registered this device has been unloaded, and if class_get_devdata()
  87            points to something in the body of that driver, it is also invalid. */
  88         struct mutex ops_lock;
  89         const struct backlight_ops *ops;
  90
  91         /* The framebuffer notifier block */
  92         struct notifier_block fb_notif;
  93
  94         struct device dev;
  95 };
  96
  97 static inline void backlight_update_status(struct backlight_device *bd)
  98 {
  99         mutex_lock(&bd->update_lock);
 100         if (bd->ops && bd->ops->update_status)
 101                 bd->ops->update_status(bd);
 102         mutex_unlock(&bd->update_lock);
 103 }
 104
 105 extern struct backlight_device *backlight_device_register(const char *name,
 106         struct device *dev, void *devdata, const struct backlight_ops *ops);
 107 extern void backlight_device_unregister(struct backlight_device *bd);
 108 extern void backlight_force_update(struct backlight_device *bd,
 109                                    enum backlight_update_reason reason);
 110
 111 #define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)
 112
 113 static inline void * bl_get_data(struct backlight_device *bl_dev)
 114 {
 115         return dev_get_drvdata(&bl_dev->dev);
 116 }
 117
 118 struct generic_bl_info {
 119         const char *name;
 120         int max_intensity;
 121         int default_intensity;
 122         int limit_mask;
 123         void (*set_bl_intensity)(int intensity);
 124         void (*kick_battery)(void);
 125 };
 126
 127 #endif