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