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
73 struct device 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, dev)
89
90 static inline void * bl_get_data(struct backlight_device *bl_dev)
91 {
92 return dev_get_drvdata(&bl_dev->dev);
93 }
94
95 struct generic_bl_info {
96 const char *name;
97 int max_intensity;
98 int default_intensity;
99 int limit_mask;
100 void (*set_bl_intensity)(int intensity);
101 void (*kick_battery)(void);
102 };
103
104 #endif
105
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