root/include/linux/backlight.h

INCLUDED FROM

DEFINITIONS

1. backlight_update_status
2. backlight_enable
3. backlight_disable
4. backlight_put
5. bl_get_data
6. of_find_backlight_by_node
7. of_find_backlight
8. devm_of_find_backlight

   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 enum backlight_scale {
  50         BACKLIGHT_SCALE_UNKNOWN = 0,
  51         BACKLIGHT_SCALE_LINEAR,
  52         BACKLIGHT_SCALE_NON_LINEAR,
  53 };
  54 
  55 struct backlight_device;
  56 struct fb_info;
  57 
  58 struct 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 */
  74 struct 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 
  97 struct 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 
 124 static 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  */
 140 static 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  */
 156 static 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  */
 172 static inline void backlight_put(struct backlight_device *bd)
 173 {
 174         if (bd)
 175                 put_device(&bd->dev);
 176 }
 177 
 178 extern 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);
 181 extern 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);
 185 extern void backlight_device_unregister(struct backlight_device *bd);
 186 extern void devm_backlight_device_unregister(struct device *dev,
 187                                         struct backlight_device *bd);
 188 extern void backlight_force_update(struct backlight_device *bd,
 189                                    enum backlight_update_reason reason);
 190 extern int backlight_register_notifier(struct notifier_block *nb);
 191 extern int backlight_unregister_notifier(struct notifier_block *nb);
 192 extern struct backlight_device *backlight_device_get_by_type(enum backlight_type type);
 193 extern int backlight_device_set_brightness(struct backlight_device *bd, unsigned long brightness);
 194 
 195 #define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)
 196 
 197 static inline void * bl_get_data(struct backlight_device *bl_dev)
 198 {
 199         return dev_get_drvdata(&bl_dev->dev);
 200 }
 201 
 202 struct generic_bl_info {
 203         const char *name;
 204         int max_intensity;
 205         int default_intensity;
 206         int limit_mask;
 207         void (*set_bl_intensity)(int intensity);
 208         void (*kick_battery)(void);
 209 };
 210 
 211 #ifdef CONFIG_OF
 212 struct backlight_device *of_find_backlight_by_node(struct device_node *node);
 213 #else
 214 static inline struct backlight_device *
 215 of_find_backlight_by_node(struct device_node *node)
 216 {
 217         return NULL;
 218 }
 219 #endif
 220 
 221 #if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
 222 struct backlight_device *of_find_backlight(struct device *dev);
 223 struct backlight_device *devm_of_find_backlight(struct device *dev);
 224 #else
 225 static inline struct backlight_device *of_find_backlight(struct device *dev)
 226 {
 227         return NULL;
 228 }
 229 
 230 static inline struct backlight_device *
 231 devm_of_find_backlight(struct device *dev)
 232 {
 233         return NULL;
 234 }
 235 #endif
 236 
 237 #endif