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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 enum backlight_update_reason {
31 	BACKLIGHT_UPDATE_HOTKEY,
32 	BACKLIGHT_UPDATE_SYSFS,
33 };
34 
35 enum backlight_type {
36 	BACKLIGHT_RAW = 1,
37 	BACKLIGHT_PLATFORM,
38 	BACKLIGHT_FIRMWARE,
39 	BACKLIGHT_TYPE_MAX,
40 };
41 
42 struct backlight_device;
43 struct fb_info;
44 
45 struct backlight_ops {
46 	unsigned int options;
47 
48 #define BL_CORE_SUSPENDRESUME	(1 << 0)
49 
50 	/* Notify the backlight driver some property has changed */
51 	int (*update_status)(struct backlight_device *);
52 	/* Return the current backlight brightness (accounting for power,
53 	   fb_blank etc.) */
54 	int (*get_brightness)(struct backlight_device *);
55 	/* Check if given framebuffer device is the one bound to this backlight;
56 	   return 0 if not, !=0 if it is. If NULL, backlight always matches the fb. */
57 	int (*check_fb)(struct backlight_device *, struct fb_info *);
58 };
59 
60 /* This structure defines all the properties of a backlight */
61 struct backlight_properties {
62 	/* Current User requested brightness (0 - max_brightness) */
63 	int brightness;
64 	/* Maximal value for brightness (read-only) */
65 	int max_brightness;
66 	/* Current FB Power mode (0: full on, 1..3: power saving
67 	   modes; 4: full off), see FB_BLANK_XXX */
68 	int power;
69 	/* FB Blanking active? (values as for power) */
70 	/* Due to be removed, please use (state & BL_CORE_FBBLANK) */
71 	int fb_blank;
72 	/* Backlight type */
73 	enum backlight_type type;
74 	/* Flags used to signal drivers of state changes */
75 	/* Upper 4 bits are reserved for driver internal use */
76 	unsigned int state;
77 
78 #define BL_CORE_SUSPENDED	(1 << 0)	/* backlight is suspended */
79 #define BL_CORE_FBBLANK		(1 << 1)	/* backlight is under an fb blank event */
80 #define BL_CORE_DRIVER4		(1 << 28)	/* reserved for driver specific use */
81 #define BL_CORE_DRIVER3		(1 << 29)	/* reserved for driver specific use */
82 #define BL_CORE_DRIVER2		(1 << 30)	/* reserved for driver specific use */
83 #define BL_CORE_DRIVER1		(1 << 31)	/* reserved for driver specific use */
84 
85 };
86 
87 struct backlight_device {
88 	/* Backlight properties */
89 	struct backlight_properties props;
90 
91 	/* Serialise access to update_status method */
92 	struct mutex update_lock;
93 
94 	/* This protects the 'ops' field. If 'ops' is NULL, the driver that
95 	   registered this device has been unloaded, and if class_get_devdata()
96 	   points to something in the body of that driver, it is also invalid. */
97 	struct mutex ops_lock;
98 	const struct backlight_ops *ops;
99 
100 	/* The framebuffer notifier block */
101 	struct notifier_block fb_notif;
102 
103 	struct device dev;
104 };
105 
backlight_update_status(struct backlight_device * bd)106 static inline void backlight_update_status(struct backlight_device *bd)
107 {
108 	mutex_lock(&bd->update_lock);
109 	if (bd->ops && bd->ops->update_status)
110 		bd->ops->update_status(bd);
111 	mutex_unlock(&bd->update_lock);
112 }
113 
114 extern struct backlight_device *backlight_device_register(const char *name,
115 	struct device *dev, void *devdata, const struct backlight_ops *ops,
116 	const struct backlight_properties *props);
117 extern void backlight_device_unregister(struct backlight_device *bd);
118 extern void backlight_force_update(struct backlight_device *bd,
119 				   enum backlight_update_reason reason);
120 
121 #define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)
122 
bl_get_data(struct backlight_device * bl_dev)123 static inline void * bl_get_data(struct backlight_device *bl_dev)
124 {
125 	return dev_get_drvdata(&bl_dev->dev);
126 }
127 
128 struct generic_bl_info {
129 	const char *name;
130 	int max_intensity;
131 	int default_intensity;
132 	int limit_mask;
133 	void (*set_bl_intensity)(int intensity);
134 	void (*kick_battery)(void);
135 };
136 
137 #ifdef CONFIG_OF
138 struct backlight_device *of_find_backlight_by_node(struct device_node *node);
139 #else
140 static inline struct backlight_device *
of_find_backlight_by_node(struct device_node * node)141 of_find_backlight_by_node(struct device_node *node)
142 {
143 	return NULL;
144 }
145 #endif
146 
147 #endif
148