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 230