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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
88};
89
90struct 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
117static 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 */
133static 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 */
149static 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 */
165static inline void backlight_put(struct backlight_device *bd)
166{
167 if (bd)
168 put_device(&bd->dev);
169}
170
171extern 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);
174extern 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);
178extern void backlight_device_unregister(struct backlight_device *bd);
179extern void devm_backlight_device_unregister(struct device *dev,
180 struct backlight_device *bd);
181extern void backlight_force_update(struct backlight_device *bd,
182 enum backlight_update_reason reason);
183extern int backlight_register_notifier(struct notifier_block *nb);
184extern int backlight_unregister_notifier(struct notifier_block *nb);
185extern struct backlight_device *backlight_device_get_by_type(enum backlight_type type);
186extern 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
190static inline void * bl_get_data(struct backlight_device *bl_dev)
191{
192 return dev_get_drvdata(&bl_dev->dev);
193}
194
195struct 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
205struct backlight_device *of_find_backlight_by_node(struct device_node *node);
206#else
207static inline struct backlight_device *
208of_find_backlight_by_node(struct device_node *node)
209{
210 return NULL;
211}
212#endif
213
214#if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
215struct backlight_device *of_find_backlight(struct device *dev);
216struct backlight_device *devm_of_find_backlight(struct device *dev);
217#else
218static inline struct backlight_device *of_find_backlight(struct device *dev)
219{
220 return NULL;
221}
222
223static inline struct backlight_device *
224devm_of_find_backlight(struct device *dev)
225{
226 return NULL;
227}
228#endif
229
230#endif