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 enum backlight_type {
  36         BACKLIGHT_RAW = 1,
  37         BACKLIGHT_PLATFORM,
  38         BACKLIGHT_FIRMWARE,
  39         BACKLIGHT_TYPE_MAX,
  40 };
  41
  42 struct backlight_device;
  43 struct fb_info;
  44
  45 struct backlight_ops {
  46         unsigned int options;
  47
  48 #define BL_CORE_SUSPENDRESUME   (1 << 0)
  49
  50         /* Notify the backlight driver some property has changed */
  51         int (*update_status)(struct backlight_device *);
  52         /* Return the current backlight brightness (accounting for power,
  53            fb_blank etc.) */
  54         int (*get_brightness)(struct backlight_device *);
  55         /* Check if given framebuffer device is the one bound to this backlight;
  56            return 0 if not, !=0 if it is. If NULL, backlight always matches the fb. */
  57         int (*check_fb)(struct backlight_device *, struct fb_info *);
  58 };
  59
  60 /* This structure defines all the properties of a backlight */
  61 struct backlight_properties {
  62         /* Current User requested brightness (0 - max_brightness) */
  63         int brightness;
  64         /* Maximal value for brightness (read-only) */
  65         int max_brightness;
  66         /* Current FB Power mode (0: full on, 1..3: power saving
  67            modes; 4: full off), see FB_BLANK_XXX */
  68         int power;
  69         /* FB Blanking active? (values as for power) */
  70         /* Due to be removed, please use (state & BL_CORE_FBBLANK) */
  71         int fb_blank;
  72         /* Backlight type */
  73         enum backlight_type type;
  74         /* Flags used to signal drivers of state changes */
  75         /* Upper 4 bits are reserved for driver internal use */
  76         unsigned int state;
  77
  78 #define BL_CORE_SUSPENDED       (1 << 0)        /* backlight is suspended */
  79 #define BL_CORE_FBBLANK         (1 << 1)        /* backlight is under an fb blank event */
  80 #define BL_CORE_DRIVER4         (1 << 28)       /* reserved for driver specific use */
  81 #define BL_CORE_DRIVER3         (1 << 29)       /* reserved for driver specific use */
  82 #define BL_CORE_DRIVER2         (1 << 30)       /* reserved for driver specific use */
  83 #define BL_CORE_DRIVER1         (1 << 31)       /* reserved for driver specific use */
  84
  85 };
  86
  87 struct backlight_device {
  88         /* Backlight properties */
  89         struct backlight_properties props;
  90
  91         /* Serialise access to update_status method */
  92         struct mutex update_lock;
  93
  94         /* This protects the 'ops' field. If 'ops' is NULL, the driver that
  95            registered this device has been unloaded, and if class_get_devdata()
  96            points to something in the body of that driver, it is also invalid. */
  97         struct mutex ops_lock;
  98         const struct backlight_ops *ops;
  99
 100         /* The framebuffer notifier block */
 101         struct notifier_block fb_notif;
 102
 103         struct device dev;
 104 };
 105
 106 static inline void backlight_update_status(struct backlight_device *bd)
 107 {
 108         mutex_lock(&bd->update_lock);
 109         if (bd->ops && bd->ops->update_status)
 110                 bd->ops->update_status(bd);
 111         mutex_unlock(&bd->update_lock);
 112 }
 113
 114 extern struct backlight_device *backlight_device_register(const char *name,
 115         struct device *dev, void *devdata, const struct backlight_ops *ops,
 116         const struct backlight_properties *props);
 117 extern void backlight_device_unregister(struct backlight_device *bd);
 118 extern void backlight_force_update(struct backlight_device *bd,
 119                                    enum backlight_update_reason reason);
 120
 121 #define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)
 122
 123 static inline void * bl_get_data(struct backlight_device *bl_dev)
 124 {
 125         return dev_get_drvdata(&bl_dev->dev);
 126 }
 127
 128 struct generic_bl_info {
 129         const char *name;
 130         int max_intensity;
 131         int default_intensity;
 132         int limit_mask;
 133         void (*set_bl_intensity)(int intensity);
 134         void (*kick_battery)(void);
 135 };
 136
 137 #ifdef CONFIG_OF
 138 struct backlight_device *of_find_backlight_by_node(struct device_node *node);
 139 #else
 140 static inline struct backlight_device *
 141 of_find_backlight_by_node(struct device_node *node)
 142 {
 143         return NULL;
 144 }
 145 #endif
 146
 147 #endif