linux/include/linux/backlight.h
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   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
  30enum backlight_update_reason {
  31        BACKLIGHT_UPDATE_HOTKEY,
  32        BACKLIGHT_UPDATE_SYSFS,
  33};
  34
  35enum backlight_type {
  36        BACKLIGHT_RAW = 1,
  37        BACKLIGHT_PLATFORM,
  38        BACKLIGHT_FIRMWARE,
  39        BACKLIGHT_TYPE_MAX,
  40};
  41
  42struct backlight_device;
  43struct fb_info;
  44
  45struct 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 */
  61struct 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
  87struct 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
 106static 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
 114extern 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);
 117extern void backlight_device_unregister(struct backlight_device *bd);
 118extern 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
 123static inline void * bl_get_data(struct backlight_device *bl_dev)
 124{
 125        return dev_get_drvdata(&bl_dev->dev);
 126}
 127
 128struct 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
 138struct backlight_device *of_find_backlight_by_node(struct device_node *node);
 139#else
 140static inline struct backlight_device *
 141of_find_backlight_by_node(struct device_node *node)
 142{
 143        return NULL;
 144}
 145#endif
 146
 147#endif
 148
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