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
  49enum backlight_scale {
  50        BACKLIGHT_SCALE_UNKNOWN = 0,
  51        BACKLIGHT_SCALE_LINEAR,
  52        BACKLIGHT_SCALE_NON_LINEAR,
  53};
  54
  55struct backlight_device;
  56struct fb_info;
  57
  58struct backlight_ops {
  59        unsigned int options;
  60
  61#define BL_CORE_SUSPENDRESUME   (1 << 0)
  62
  63        /* Notify the backlight driver some property has changed */
  64        int (*update_status)(struct backlight_device *);
  65        /* Return the current backlight brightness (accounting for power,
  66           fb_blank etc.) */
  67        int (*get_brightness)(struct backlight_device *);
  68        /* Check if given framebuffer device is the one bound to this backlight;
  69           return 0 if not, !=0 if it is. If NULL, backlight always matches the fb. */
  70        int (*check_fb)(struct backlight_device *, struct fb_info *);
  71};
  72
  73/* This structure defines all the properties of a backlight */
  74struct backlight_properties {
  75        /* Current User requested brightness (0 - max_brightness) */
  76        int brightness;
  77        /* Maximal value for brightness (read-only) */
  78        int max_brightness;
  79        /* Current FB Power mode (0: full on, 1..3: power saving
  80           modes; 4: full off), see FB_BLANK_XXX */
  81        int power;
  82        /* FB Blanking active? (values as for power) */
  83        /* Due to be removed, please use (state & BL_CORE_FBBLANK) */
  84        int fb_blank;
  85        /* Backlight type */
  86        enum backlight_type type;
  87        /* Flags used to signal drivers of state changes */
  88        unsigned int state;
  89        /* Type of the brightness scale (linear, non-linear, ...) */
  90        enum backlight_scale scale;
  91
  92#define BL_CORE_SUSPENDED       (1 << 0)        /* backlight is suspended */
  93#define BL_CORE_FBBLANK         (1 << 1)        /* backlight is under an fb blank event */
  94
  95};
  96
  97struct backlight_device {
  98        /* Backlight properties */
  99        struct backlight_properties props;
 100
 101        /* Serialise access to update_status method */
 102        struct mutex update_lock;
 103
 104        /* This protects the 'ops' field. If 'ops' is NULL, the driver that
 105           registered this device has been unloaded, and if class_get_devdata()
 106           points to something in the body of that driver, it is also invalid. */
 107        struct mutex ops_lock;
 108        const struct backlight_ops *ops;
 109
 110        /* The framebuffer notifier block */
 111        struct notifier_block fb_notif;
 112
 113        /* list entry of all registered backlight devices */
 114        struct list_head entry;
 115
 116        struct device dev;
 117
 118        /* Multiple framebuffers may share one backlight device */
 119        bool fb_bl_on[FB_MAX];
 120
 121        int use_count;
 122};
 123
 124static inline int backlight_update_status(struct backlight_device *bd)
 125{
 126        int ret = -ENOENT;
 127
 128        mutex_lock(&bd->update_lock);
 129        if (bd->ops && bd->ops->update_status)
 130                ret = bd->ops->update_status(bd);
 131        mutex_unlock(&bd->update_lock);
 132
 133        return ret;
 134}
 135
 136/**
 137 * backlight_enable - Enable backlight
 138 * @bd: the backlight device to enable
 139 */
 140static inline int backlight_enable(struct backlight_device *bd)
 141{
 142        if (!bd)
 143                return 0;
 144
 145        bd->props.power = FB_BLANK_UNBLANK;
 146        bd->props.fb_blank = FB_BLANK_UNBLANK;
 147        bd->props.state &= ~BL_CORE_FBBLANK;
 148
 149        return backlight_update_status(bd);
 150}
 151
 152/**
 153 * backlight_disable - Disable backlight
 154 * @bd: the backlight device to disable
 155 */
 156static inline int backlight_disable(struct backlight_device *bd)
 157{
 158        if (!bd)
 159                return 0;
 160
 161        bd->props.power = FB_BLANK_POWERDOWN;
 162        bd->props.fb_blank = FB_BLANK_POWERDOWN;
 163        bd->props.state |= BL_CORE_FBBLANK;
 164
 165        return backlight_update_status(bd);
 166}
 167
 168/**
 169 * backlight_put - Drop backlight reference
 170 * @bd: the backlight device to put
 171 */
 172static inline void backlight_put(struct backlight_device *bd)
 173{
 174        if (bd)
 175                put_device(&bd->dev);
 176}
 177
 178extern struct backlight_device *backlight_device_register(const char *name,
 179        struct device *dev, void *devdata, const struct backlight_ops *ops,
 180        const struct backlight_properties *props);
 181extern struct backlight_device *devm_backlight_device_register(
 182        struct device *dev, const char *name, struct device *parent,
 183        void *devdata, const struct backlight_ops *ops,
 184        const struct backlight_properties *props);
 185extern void backlight_device_unregister(struct backlight_device *bd);
 186extern void devm_backlight_device_unregister(struct device *dev,
 187                                        struct backlight_device *bd);
 188extern void backlight_force_update(struct backlight_device *bd,
 189                                   enum backlight_update_reason reason);
 190extern int backlight_register_notifier(struct notifier_block *nb);
 191extern int backlight_unregister_notifier(struct notifier_block *nb);
 192extern struct backlight_device *backlight_device_get_by_type(enum backlight_type type);
 193struct backlight_device *backlight_device_get_by_name(const char *name);
 194extern int backlight_device_set_brightness(struct backlight_device *bd, unsigned long brightness);
 195
 196#define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)
 197
 198static inline void * bl_get_data(struct backlight_device *bl_dev)
 199{
 200        return dev_get_drvdata(&bl_dev->dev);
 201}
 202
 203struct generic_bl_info {
 204        const char *name;
 205        int max_intensity;
 206        int default_intensity;
 207        int limit_mask;
 208        void (*set_bl_intensity)(int intensity);
 209        void (*kick_battery)(void);
 210};
 211
 212#ifdef CONFIG_OF
 213struct backlight_device *of_find_backlight_by_node(struct device_node *node);
 214#else
 215static inline struct backlight_device *
 216of_find_backlight_by_node(struct device_node *node)
 217{
 218        return NULL;
 219}
 220#endif
 221
 222#if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
 223struct backlight_device *of_find_backlight(struct device *dev);
 224struct backlight_device *devm_of_find_backlight(struct device *dev);
 225#else
 226static inline struct backlight_device *of_find_backlight(struct device *dev)
 227{
 228        return NULL;
 229}
 230
 231static inline struct backlight_device *
 232devm_of_find_backlight(struct device *dev)
 233{
 234        return NULL;
 235}
 236#endif
 237
 238#endif
 239