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/fb.h>
  13 #include <linux/mutex.h>
  14 #include <linux/notifier.h>
  15
  16 /* Notes on locking:
  17  *
  18  * backlight_device->ops_lock is an internal backlight lock protecting the
  19  * ops pointer and no code outside the core should need to touch it.
  20  *
  21  * Access to update_status() is serialised by the update_lock mutex since
  22  * most drivers seem to need this and historically get it wrong.
  23  *
  24  * Most drivers don't need locking on their get_brightness() method.
  25  * If yours does, you need to implement it in the driver. You can use the
  26  * update_lock mutex if appropriate.
  27  *
  28  * Any other use of the locks below is probably wrong.
  29  */
  30
  31 enum backlight_update_reason {
  32         BACKLIGHT_UPDATE_HOTKEY,
  33         BACKLIGHT_UPDATE_SYSFS,
  34 };
  35
  36 enum backlight_type {
  37         BACKLIGHT_RAW = 1,
  38         BACKLIGHT_PLATFORM,
  39         BACKLIGHT_FIRMWARE,
  40         BACKLIGHT_TYPE_MAX,
  41 };
  42
  43 enum backlight_notification {
  44         BACKLIGHT_REGISTERED,
  45         BACKLIGHT_UNREGISTERED,
  46 };
  47
  48 struct backlight_device;
  49 struct fb_info;
  50
  51 struct backlight_ops {
  52         unsigned int options;
  53
  54 #define BL_CORE_SUSPENDRESUME   (1 << 0)
  55
  56         /* Notify the backlight driver some property has changed */
  57         int (*update_status)(struct backlight_device *);
  58         /* Return the current backlight brightness (accounting for power,
  59            fb_blank etc.) */
  60         int (*get_brightness)(struct backlight_device *);
  61         /* Check if given framebuffer device is the one bound to this backlight;
  62            return 0 if not, !=0 if it is. If NULL, backlight always matches the fb. */
  63         int (*check_fb)(struct backlight_device *, struct fb_info *);
  64 };
  65
  66 /* This structure defines all the properties of a backlight */
  67 struct backlight_properties {
  68         /* Current User requested brightness (0 - max_brightness) */
  69         int brightness;
  70         /* Maximal value for brightness (read-only) */
  71         int max_brightness;
  72         /* Current FB Power mode (0: full on, 1..3: power saving
  73            modes; 4: full off), see FB_BLANK_XXX */
  74         int power;
  75         /* FB Blanking active? (values as for power) */
  76         /* Due to be removed, please use (state & BL_CORE_FBBLANK) */
  77         int fb_blank;
  78         /* Backlight type */
  79         enum backlight_type type;
  80         /* Flags used to signal drivers of state changes */
  81         /* Upper 4 bits are reserved for driver internal use */
  82         unsigned int state;
  83
  84 #define BL_CORE_SUSPENDED       (1 << 0)        /* backlight is suspended */
  85 #define BL_CORE_FBBLANK         (1 << 1)        /* backlight is under an fb blank event */
  86 #define BL_CORE_DRIVER4         (1 << 28)       /* reserved for driver specific use */
  87 #define BL_CORE_DRIVER3         (1 << 29)       /* reserved for driver specific use */
  88 #define BL_CORE_DRIVER2         (1 << 30)       /* reserved for driver specific use */
  89 #define BL_CORE_DRIVER1         (1 << 31)       /* reserved for driver specific use */
  90
  91 };
  92
  93 struct backlight_device {
  94         /* Backlight properties */
  95         struct backlight_properties props;
  96
  97         /* Serialise access to update_status method */
  98         struct mutex update_lock;
  99
 100         /* This protects the 'ops' field. If 'ops' is NULL, the driver that
 101            registered this device has been unloaded, and if class_get_devdata()
 102            points to something in the body of that driver, it is also invalid. */
 103         struct mutex ops_lock;
 104         const struct backlight_ops *ops;
 105
 106         /* The framebuffer notifier block */
 107         struct notifier_block fb_notif;
 108
 109         /* list entry of all registered backlight devices */
 110         struct list_head entry;
 111
 112         struct device dev;
 113
 114         /* Multiple framebuffers may share one backlight device */
 115         bool fb_bl_on[FB_MAX];
 116
 117         int use_count;
 118 };
 119
 120 static inline int backlight_update_status(struct backlight_device *bd)
 121 {
 122         int ret = -ENOENT;
 123
 124         mutex_lock(&bd->update_lock);
 125         if (bd->ops && bd->ops->update_status)
 126                 ret = bd->ops->update_status(bd);
 127         mutex_unlock(&bd->update_lock);
 128
 129         return ret;
 130 }
 131
 132 extern struct backlight_device *backlight_device_register(const char *name,
 133         struct device *dev, void *devdata, const struct backlight_ops *ops,
 134         const struct backlight_properties *props);
 135 extern struct backlight_device *devm_backlight_device_register(
 136         struct device *dev, const char *name, struct device *parent,
 137         void *devdata, const struct backlight_ops *ops,
 138         const struct backlight_properties *props);
 139 extern void backlight_device_unregister(struct backlight_device *bd);
 140 extern void devm_backlight_device_unregister(struct device *dev,
 141                                         struct backlight_device *bd);
 142 extern void backlight_force_update(struct backlight_device *bd,
 143                                    enum backlight_update_reason reason);
 144 extern bool backlight_device_registered(enum backlight_type type);
 145 extern int backlight_register_notifier(struct notifier_block *nb);
 146 extern int backlight_unregister_notifier(struct notifier_block *nb);
 147
 148 #define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)
 149
 150 static inline void * bl_get_data(struct backlight_device *bl_dev)
 151 {
 152         return dev_get_drvdata(&bl_dev->dev);
 153 }
 154
 155 struct generic_bl_info {
 156         const char *name;
 157         int max_intensity;
 158         int default_intensity;
 159         int limit_mask;
 160         void (*set_bl_intensity)(int intensity);
 161         void (*kick_battery)(void);
 162 };
 163
 164 #ifdef CONFIG_OF
 165 struct backlight_device *of_find_backlight_by_node(struct device_node *node);
 166 #else
 167 static inline struct backlight_device *
 168 of_find_backlight_by_node(struct device_node *node)
 169 {
 170         return NULL;
 171 }
 172 #endif
 173
 174 #endif