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 /* Upper 4 bits are reserved for driver internal use */ 83 unsigned int state; 84 85 #define BL_CORE_SUSPENDED (1 << 0) /* backlight is suspended */ 86 #define BL_CORE_FBBLANK (1 << 1) /* backlight is under an fb blank event */ 87 #define BL_CORE_DRIVER4 (1 << 28) /* reserved for driver specific use */ 88 #define BL_CORE_DRIVER3 (1 << 29) /* reserved for driver specific use */ 89 #define BL_CORE_DRIVER2 (1 << 30) /* reserved for driver specific use */ 90 #define BL_CORE_DRIVER1 (1 << 31) /* reserved for driver specific use */ 91 92 }; 93 94 struct backlight_device { 95 /* Backlight properties */ 96 struct backlight_properties props; 97 98 /* Serialise access to update_status method */ 99 struct mutex update_lock; 100 101 /* This protects the 'ops' field. If 'ops' is NULL, the driver that 102 registered this device has been unloaded, and if class_get_devdata() 103 points to something in the body of that driver, it is also invalid. */ 104 struct mutex ops_lock; 105 const struct backlight_ops *ops; 106 107 /* The framebuffer notifier block */ 108 struct notifier_block fb_notif; 109 110 /* list entry of all registered backlight devices */ 111 struct list_head entry; 112 113 struct device dev; 114 115 /* Multiple framebuffers may share one backlight device */ 116 bool fb_bl_on[FB_MAX]; 117 118 int use_count; 119 }; 120 121 static inline int backlight_update_status(struct backlight_device *bd) 122 { 123 int ret = -ENOENT; 124 125 mutex_lock(&bd->update_lock); 126 if (bd->ops && bd->ops->update_status) 127 ret = bd->ops->update_status(bd); 128 mutex_unlock(&bd->update_lock); 129 130 return ret; 131 } 132 133 /** 134 * backlight_enable - Enable backlight 135 * @bd: the backlight device to enable 136 */ 137 static inline int backlight_enable(struct backlight_device *bd) 138 { 139 if (!bd) 140 return 0; 141 142 bd->props.power = FB_BLANK_UNBLANK; 143 bd->props.fb_blank = FB_BLANK_UNBLANK; 144 bd->props.state &= ~BL_CORE_FBBLANK; 145 146 return backlight_update_status(bd); 147 } 148 149 /** 150 * backlight_disable - Disable backlight 151 * @bd: the backlight device to disable 152 */ 153 static inline int backlight_disable(struct backlight_device *bd) 154 { 155 if (!bd) 156 return 0; 157 158 bd->props.power = FB_BLANK_POWERDOWN; 159 bd->props.fb_blank = FB_BLANK_POWERDOWN; 160 bd->props.state |= BL_CORE_FBBLANK; 161 162 return backlight_update_status(bd); 163 } 164 165 /** 166 * backlight_put - Drop backlight reference 167 * @bd: the backlight device to put 168 */ 169 static inline void backlight_put(struct backlight_device *bd) 170 { 171 if (bd) 172 put_device(&bd->dev); 173 } 174 175 extern struct backlight_device *backlight_device_register(const char *name, 176 struct device *dev, void *devdata, const struct backlight_ops *ops, 177 const struct backlight_properties *props); 178 extern struct backlight_device *devm_backlight_device_register( 179 struct device *dev, const char *name, struct device *parent, 180 void *devdata, const struct backlight_ops *ops, 181 const struct backlight_properties *props); 182 extern void backlight_device_unregister(struct backlight_device *bd); 183 extern void devm_backlight_device_unregister(struct device *dev, 184 struct backlight_device *bd); 185 extern void backlight_force_update(struct backlight_device *bd, 186 enum backlight_update_reason reason); 187 extern int backlight_register_notifier(struct notifier_block *nb); 188 extern int backlight_unregister_notifier(struct notifier_block *nb); 189 extern struct backlight_device *backlight_device_get_by_type(enum backlight_type type); 190 extern int backlight_device_set_brightness(struct backlight_device *bd, unsigned long brightness); 191 192 #define to_backlight_device(obj) container_of(obj, struct backlight_device, dev) 193 194 static inline void * bl_get_data(struct backlight_device *bl_dev) 195 { 196 return dev_get_drvdata(&bl_dev->dev); 197 } 198 199 struct generic_bl_info { 200 const char *name; 201 int max_intensity; 202 int default_intensity; 203 int limit_mask; 204 void (*set_bl_intensity)(int intensity); 205 void (*kick_battery)(void); 206 }; 207 208 #ifdef CONFIG_OF 209 struct backlight_device *of_find_backlight_by_node(struct device_node *node); 210 #else 211 static inline struct backlight_device * 212 of_find_backlight_by_node(struct device_node *node) 213 { 214 return NULL; 215 } 216 #endif 217 218 #if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE) 219 struct backlight_device *of_find_backlight(struct device *dev); 220 struct backlight_device *devm_of_find_backlight(struct device *dev); 221 #else 222 static inline struct backlight_device *of_find_backlight(struct device *dev) 223 { 224 return NULL; 225 } 226 227 static inline struct backlight_device * 228 devm_of_find_backlight(struct device *dev) 229 { 230 return NULL; 231 } 232 #endif 233 234 #endif 235