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
  32 enum backlight_update_reason {
  33         BACKLIGHT_UPDATE_HOTKEY,
  34         BACKLIGHT_UPDATE_SYSFS,
  35 };
  36
  37 enum backlight_type {
  38         BACKLIGHT_RAW = 1,
  39         BACKLIGHT_PLATFORM,
  40         BACKLIGHT_FIRMWARE,
  41         BACKLIGHT_TYPE_MAX,
  42 };
  43
  44 enum backlight_notification {
  45         BACKLIGHT_REGISTERED,
  46         BACKLIGHT_UNREGISTERED,
  47 };
  48
  49 struct backlight_device;
  50 struct fb_info;
  51
  52 struct 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 */
  68 struct 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
  89 struct 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
 116 static 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  */
 132 static 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  */
 148 static 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  */
 164 static inline void backlight_put(struct backlight_device *bd)
 165 {
 166         if (bd)
 167                 put_device(&bd->dev);
 168 }
 169
 170 extern 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);
 173 extern 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);
 177 extern void backlight_device_unregister(struct backlight_device *bd);
 178 extern void devm_backlight_device_unregister(struct device *dev,
 179                                         struct backlight_device *bd);
 180 extern void backlight_force_update(struct backlight_device *bd,
 181                                    enum backlight_update_reason reason);
 182 extern int backlight_register_notifier(struct notifier_block *nb);
 183 extern int backlight_unregister_notifier(struct notifier_block *nb);
 184 extern struct backlight_device *backlight_device_get_by_type(enum backlight_type type);
 185 extern 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
 189 static inline void * bl_get_data(struct backlight_device *bl_dev)
 190 {
 191         return dev_get_drvdata(&bl_dev->dev);
 192 }
 193
 194 struct 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
 204 struct backlight_device *of_find_backlight_by_node(struct device_node *node);
 205 #else
 206 static inline struct backlight_device *
 207 of_find_backlight_by_node(struct device_node *node)
 208 {
 209         return NULL;
 210 }
 211 #endif
 212
 213 #if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
 214 struct backlight_device *of_find_backlight(struct device *dev);
 215 struct backlight_device *devm_of_find_backlight(struct device *dev);
 216 #else
 217 static inline struct backlight_device *of_find_backlight(struct device *dev)
 218 {
 219         return NULL;
 220 }
 221
 222 static inline struct backlight_device *
 223 devm_of_find_backlight(struct device *dev)
 224 {
 225         return NULL;
 226 }
 227 #endif
 228
 229 #endif