LXR linux/include/linux/backlight.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2/*
   3 * Backlight Lowlevel Control Abstraction
   4 *
   5 * Copyright (C) 2003,2004 Hewlett-Packard Company
   6 *
   7 */
   8
   9#ifndef _LINUX_BACKLIGHT_H
  10#define _LINUX_BACKLIGHT_H
  11
  12#include <linux/device.h>
  13#include <linux/fb.h>
  14#include <linux/mutex.h>
  15#include <linux/notifier.h>
  16
  17/* Notes on locking:
  18 *
  19 * backlight_device->ops_lock is an internal backlight lock protecting the
  20 * ops pointer and no code outside the core should need to touch it.
  21 *
  22 * Access to update_status() is serialised by the update_lock mutex since
  23 * most drivers seem to need this and historically get it wrong.
  24 *
  25 * Most drivers don't need locking on their get_brightness() method.
  26 * If yours does, you need to implement it in the driver. You can use the
  27 * update_lock mutex if appropriate.
  28 *
  29 * Any other use of the locks below is probably wrong.
  30 */
  31
  32enum backlight_update_reason {
  33        BACKLIGHT_UPDATE_HOTKEY,
  34        BACKLIGHT_UPDATE_SYSFS,
  35};
  36
  37enum backlight_type {
  38        BACKLIGHT_RAW = 1,
  39        BACKLIGHT_PLATFORM,
  40        BACKLIGHT_FIRMWARE,
  41        BACKLIGHT_TYPE_MAX,
  42};
  43
  44enum backlight_notification {
  45        BACKLIGHT_REGISTERED,
  46        BACKLIGHT_UNREGISTERED,
  47};
  48
  49struct backlight_device;
  50struct fb_info;
  51
  52struct backlight_ops {
  53        unsigned int options;
  54
  55#define BL_CORE_SUSPENDRESUME   (1 << 0)
  56
  57        /* Notify the backlight driver some property has changed */
  58        int (*update_status)(struct backlight_device *);
  59        /* Return the current backlight brightness (accounting for power,
  60           fb_blank etc.) */
  61        int (*get_brightness)(struct backlight_device *);
  62        /* Check if given framebuffer device is the one bound to this backlight;
  63           return 0 if not, !=0 if it is. If NULL, backlight always matches the fb. */
  64        int (*check_fb)(struct backlight_device *, struct fb_info *);
  65};
  66
  67/* This structure defines all the properties of a backlight */
  68struct backlight_properties {
  69        /* Current User requested brightness (0 - max_brightness) */
  70        int brightness;
  71        /* Maximal value for brightness (read-only) */
  72        int max_brightness;
  73        /* Current FB Power mode (0: full on, 1..3: power saving
  74           modes; 4: full off), see FB_BLANK_XXX */
  75        int power;
  76        /* FB Blanking active? (values as for power) */
  77        /* Due to be removed, please use (state & BL_CORE_FBBLANK) */
  78        int fb_blank;
  79        /* Backlight type */
  80        enum backlight_type type;
  81        /* Flags used to signal drivers of state changes */
  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
  87};
  88
  89struct backlight_device {
  90        /* Backlight properties */
  91        struct backlight_properties props;
  92
  93        /* Serialise access to update_status method */
  94        struct mutex update_lock;
  95
  96        /* This protects the 'ops' field. If 'ops' is NULL, the driver that
  97           registered this device has been unloaded, and if class_get_devdata()
  98           points to something in the body of that driver, it is also invalid. */
  99        struct mutex ops_lock;
 100        const struct backlight_ops *ops;
 101
 102        /* The framebuffer notifier block */
 103        struct notifier_block fb_notif;
 104
 105        /* list entry of all registered backlight devices */
 106        struct list_head entry;
 107
 108        struct device dev;
 109
 110        /* Multiple framebuffers may share one backlight device */
 111        bool fb_bl_on[FB_MAX];
 112
 113        int use_count;
 114};
 115
 116static inline int backlight_update_status(struct backlight_device *bd)
 117{
 118        int ret = -ENOENT;
 119
 120        mutex_lock(&bd->update_lock);
 121        if (bd->ops && bd->ops->update_status)
 122                ret = bd->ops->update_status(bd);
 123        mutex_unlock(&bd->update_lock);
 124
 125        return ret;
 126}
 127
 128/**
 129 * backlight_enable - Enable backlight
 130 * @bd: the backlight device to enable
 131 */
 132static inline int backlight_enable(struct backlight_device *bd)
 133{
 134        if (!bd)
 135                return 0;
 136
 137        bd->props.power = FB_BLANK_UNBLANK;
 138        bd->props.fb_blank = FB_BLANK_UNBLANK;
 139        bd->props.state &= ~BL_CORE_FBBLANK;
 140
 141        return backlight_update_status(bd);
 142}
 143
 144/**
 145 * backlight_disable - Disable backlight
 146 * @bd: the backlight device to disable
 147 */
 148static inline int backlight_disable(struct backlight_device *bd)
 149{
 150        if (!bd)
 151                return 0;
 152
 153        bd->props.power = FB_BLANK_POWERDOWN;
 154        bd->props.fb_blank = FB_BLANK_POWERDOWN;
 155        bd->props.state |= BL_CORE_FBBLANK;
 156
 157        return backlight_update_status(bd);
 158}
 159
 160/**
 161 * backlight_put - Drop backlight reference
 162 * @bd: the backlight device to put
 163 */
 164static inline void backlight_put(struct backlight_device *bd)
 165{
 166        if (bd)
 167                put_device(&bd->dev);
 168}
 169
 170extern struct backlight_device *backlight_device_register(const char *name,
 171        struct device *dev, void *devdata, const struct backlight_ops *ops,
 172        const struct backlight_properties *props);
 173extern struct backlight_device *devm_backlight_device_register(
 174        struct device *dev, const char *name, struct device *parent,
 175        void *devdata, const struct backlight_ops *ops,
 176        const struct backlight_properties *props);
 177extern void backlight_device_unregister(struct backlight_device *bd);
 178extern void devm_backlight_device_unregister(struct device *dev,
 179                                        struct backlight_device *bd);
 180extern void backlight_force_update(struct backlight_device *bd,
 181                                   enum backlight_update_reason reason);
 182extern int backlight_register_notifier(struct notifier_block *nb);
 183extern int backlight_unregister_notifier(struct notifier_block *nb);
 184extern struct backlight_device *backlight_device_get_by_type(enum backlight_type type);
 185extern int backlight_device_set_brightness(struct backlight_device *bd, unsigned long brightness);
 186
 187#define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)
 188
 189static inline void * bl_get_data(struct backlight_device *bl_dev)
 190{
 191        return dev_get_drvdata(&bl_dev->dev);
 192}
 193
 194struct generic_bl_info {
 195        const char *name;
 196        int max_intensity;
 197        int default_intensity;
 198        int limit_mask;
 199        void (*set_bl_intensity)(int intensity);
 200        void (*kick_battery)(void);
 201};
 202
 203#ifdef CONFIG_OF
 204struct backlight_device *of_find_backlight_by_node(struct device_node *node);
 205#else
 206static inline struct backlight_device *
 207of_find_backlight_by_node(struct device_node *node)
 208{
 209        return NULL;
 210}
 211#endif
 212
 213#if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
 214struct backlight_device *of_find_backlight(struct device *dev);
 215struct backlight_device *devm_of_find_backlight(struct device *dev);
 216#else
 217static inline struct backlight_device *of_find_backlight(struct device *dev)
 218{
 219        return NULL;
 220}
 221
 222static inline struct backlight_device *
 223devm_of_find_backlight(struct device *dev)
 224{
 225        return NULL;
 226}
 227#endif
 228
 229#endif
 230