1 /* 2 * Backlight Lowlevel Control Abstraction 3 * 4 * Copyright (C) 2003,2004 Hewlett-Packard Company 5 * 6 */ 7 8 #ifndef _LINUX_BACKLIGHT_H 9 #define _LINUX_BACKLIGHT_H 10 11 #include <linux/device.h> 12 #include <linux/mutex.h> 13 #include <linux/notifier.h> 14 15 /* Notes on locking: 16 * 17 * backlight_device->ops_lock is an internal backlight lock protecting the 18 * ops pointer and no code outside the core should need to touch it. 19 * 20 * Access to update_status() is serialised by the update_lock mutex since 21 * most drivers seem to need this and historically get it wrong. 22 * 23 * Most drivers don't need locking on their get_brightness() method. 24 * If yours does, you need to implement it in the driver. You can use the 25 * update_lock mutex if appropriate. 26 * 27 * Any other use of the locks below is probably wrong. 28 */ 29 30 struct backlight_device; 31 struct fb_info; 32 33 struct backlight_ops { 34 /* Notify the backlight driver some property has changed */ 35 int (*update_status)(struct backlight_device *); 36 /* Return the current backlight brightness (accounting for power, 37 fb_blank etc.) */ 38 int (*get_brightness)(struct backlight_device *); 39 /* Check if given framebuffer device is the one bound to this backlight; 40 return 0 if not, !=0 if it is. If NULL, backlight always matches the fb. */ 41 int (*check_fb)(struct fb_info *); 42 }; 43 44 /* This structure defines all the properties of a backlight */ 45 struct backlight_properties { 46 /* Current User requested brightness (0 - max_brightness) */ 47 int brightness; 48 /* Maximal value for brightness (read-only) */ 49 int max_brightness; 50 /* Current FB Power mode (0: full on, 1..3: power saving 51 modes; 4: full off), see FB_BLANK_XXX */ 52 int power; 53 /* FB Blanking active? (values as for power) */ 54 int fb_blank; 55 }; 56 57 struct backlight_device { 58 /* Backlight properties */ 59 struct backlight_properties props; 60 61 /* Serialise access to update_status method */ 62 struct mutex update_lock; 63 64 /* This protects the 'ops' field. If 'ops' is NULL, the driver that 65 registered this device has been unloaded, and if class_get_devdata() 66 points to something in the body of that driver, it is also invalid. */ 67 struct mutex ops_lock; 68 struct backlight_ops *ops; 69 70 /* The framebuffer notifier block */ 71 struct notifier_block fb_notif; 72 /* The class device structure */ 73 struct class_device class_dev; 74 }; 75 76 static inline void backlight_update_status(struct backlight_device *bd) 77 { 78 mutex_lock(&bd->update_lock); 79 if (bd->ops && bd->ops->update_status) 80 bd->ops->update_status(bd); 81 mutex_unlock(&bd->update_lock); 82 } 83 84 extern struct backlight_device *backlight_device_register(const char *name, 85 struct device *dev, void *devdata, struct backlight_ops *ops); 86 extern void backlight_device_unregister(struct backlight_device *bd); 87 88 #define to_backlight_device(obj) container_of(obj, struct backlight_device, class_dev) 89 90 #endif 91