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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
32enum backlight_update_reason {
33 BACKLIGHT_UPDATE_HOTKEY,
34 BACKLIGHT_UPDATE_SYSFS,
35};
36
37enum backlight_type {
38 BACKLIGHT_RAW = 1,
39 BACKLIGHT_PLATFORM,
40 BACKLIGHT_FIRMWARE,
41 BACKLIGHT_TYPE_MAX,
42};
43
44enum backlight_notification {
45 BACKLIGHT_REGISTERED,
46 BACKLIGHT_UNREGISTERED,
47};
48
49struct backlight_device;
50struct fb_info;
51
52struct 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 */
68struct 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
94struct 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
121static 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
133extern struct backlight_device *backlight_device_register(const char *name,
134 struct device *dev, void *devdata, const struct backlight_ops *ops,
135 const struct backlight_properties *props);
136extern struct backlight_device *devm_backlight_device_register(
137 struct device *dev, const char *name, struct device *parent,
138 void *devdata, const struct backlight_ops *ops,
139 const struct backlight_properties *props);
140extern void backlight_device_unregister(struct backlight_device *bd);
141extern void devm_backlight_device_unregister(struct device *dev,
142 struct backlight_device *bd);
143extern void backlight_force_update(struct backlight_device *bd,
144 enum backlight_update_reason reason);
145extern int backlight_register_notifier(struct notifier_block *nb);
146extern int backlight_unregister_notifier(struct notifier_block *nb);
147extern struct backlight_device *backlight_device_get_by_type(enum backlight_type type);
148extern int backlight_device_set_brightness(struct backlight_device *bd, unsigned long brightness);
149
150#define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)
151
152static inline void * bl_get_data(struct backlight_device *bl_dev)
153{
154 return dev_get_drvdata(&bl_dev->dev);
155}
156
157struct generic_bl_info {
158 const char *name;
159 int max_intensity;
160 int default_intensity;
161 int limit_mask;
162 void (*set_bl_intensity)(int intensity);
163 void (*kick_battery)(void);
164};
165
166#ifdef CONFIG_OF
167struct backlight_device *of_find_backlight_by_node(struct device_node *node);
168#else
169static inline struct backlight_device *
170of_find_backlight_by_node(struct device_node *node)
171{
172 return NULL;
173}
174#endif
175
176#endif