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
32 enum backlight_update_reason {
33 BACKLIGHT_UPDATE_HOTKEY,
34 BACKLIGHT_UPDATE_SYSFS,
35 };
36
37 enum backlight_type {
38 BACKLIGHT_RAW = 1,
39 BACKLIGHT_PLATFORM,
40 BACKLIGHT_FIRMWARE,
41 BACKLIGHT_TYPE_MAX,
42 };
43
44 enum backlight_notification {
45 BACKLIGHT_REGISTERED,
46 BACKLIGHT_UNREGISTERED,
47 };
48
49 enum backlight_scale {
50 BACKLIGHT_SCALE_UNKNOWN = 0,
51 BACKLIGHT_SCALE_LINEAR,
52 BACKLIGHT_SCALE_NON_LINEAR,
53 };
54
55 struct backlight_device;
56 struct fb_info;
57
58 struct backlight_ops {
59 unsigned int options;
60
61 #define BL_CORE_SUSPENDRESUME (1 << 0)
62
63 /* Notify the backlight driver some property has changed */
64 int (*update_status)(struct backlight_device *);
65 /* Return the current backlight brightness (accounting for power,
66 fb_blank etc.) */
67 int (*get_brightness)(struct backlight_device *);
68 /* Check if given framebuffer device is the one bound to this backlight;
69 return 0 if not, !=0 if it is. If NULL, backlight always matches the fb. */
70 int (*check_fb)(struct backlight_device *, struct fb_info *);
71 };
72
73 /* This structure defines all the properties of a backlight */
74 struct backlight_properties {
75 /* Current User requested brightness (0 - max_brightness) */
76 int brightness;
77 /* Maximal value for brightness (read-only) */
78 int max_brightness;
79 /* Current FB Power mode (0: full on, 1..3: power saving
80 modes; 4: full off), see FB_BLANK_XXX */
81 int power;
82 /* FB Blanking active? (values as for power) */
83 /* Due to be removed, please use (state & BL_CORE_FBBLANK) */
84 int fb_blank;
85 /* Backlight type */
86 enum backlight_type type;
87 /* Flags used to signal drivers of state changes */
88 unsigned int state;
89 /* Type of the brightness scale (linear, non-linear, ...) */
90 enum backlight_scale scale;
91
92 #define BL_CORE_SUSPENDED (1 << 0) /* backlight is suspended */
93 #define BL_CORE_FBBLANK (1 << 1) /* backlight is under an fb blank event */
94
95 };
96
97 struct backlight_device {
98 /* Backlight properties */
99 struct backlight_properties props;
100
101 /* Serialise access to update_status method */
102 struct mutex update_lock;
103
104 /* This protects the 'ops' field. If 'ops' is NULL, the driver that
105 registered this device has been unloaded, and if class_get_devdata()
106 points to something in the body of that driver, it is also invalid. */
107 struct mutex ops_lock;
108 const struct backlight_ops *ops;
109
110 /* The framebuffer notifier block */
111 struct notifier_block fb_notif;
112
113 /* list entry of all registered backlight devices */
114 struct list_head entry;
115
116 struct device dev;
117
118 /* Multiple framebuffers may share one backlight device */
119 bool fb_bl_on[FB_MAX];
120
121 int use_count;
122 };
123
backlight_update_status(struct backlight_device * bd)124 static inline int backlight_update_status(struct backlight_device *bd)
125 {
126 int ret = -ENOENT;
127
128 mutex_lock(&bd->update_lock);
129 if (bd->ops && bd->ops->update_status)
130 ret = bd->ops->update_status(bd);
131 mutex_unlock(&bd->update_lock);
132
133 return ret;
134 }
135
136 /**
137 * backlight_enable - Enable backlight
138 * @bd: the backlight device to enable
139 */
backlight_enable(struct backlight_device * bd)140 static inline int backlight_enable(struct backlight_device *bd)
141 {
142 if (!bd)
143 return 0;
144
145 bd->props.power = FB_BLANK_UNBLANK;
146 bd->props.fb_blank = FB_BLANK_UNBLANK;
147 bd->props.state &= ~BL_CORE_FBBLANK;
148
149 return backlight_update_status(bd);
150 }
151
152 /**
153 * backlight_disable - Disable backlight
154 * @bd: the backlight device to disable
155 */
backlight_disable(struct backlight_device * bd)156 static inline int backlight_disable(struct backlight_device *bd)
157 {
158 if (!bd)
159 return 0;
160
161 bd->props.power = FB_BLANK_POWERDOWN;
162 bd->props.fb_blank = FB_BLANK_POWERDOWN;
163 bd->props.state |= BL_CORE_FBBLANK;
164
165 return backlight_update_status(bd);
166 }
167
168 /**
169 * backlight_put - Drop backlight reference
170 * @bd: the backlight device to put
171 */
backlight_put(struct backlight_device * bd)172 static inline void backlight_put(struct backlight_device *bd)
173 {
174 if (bd)
175 put_device(&bd->dev);
176 }
177
178 extern struct backlight_device *backlight_device_register(const char *name,
179 struct device *dev, void *devdata, const struct backlight_ops *ops,
180 const struct backlight_properties *props);
181 extern struct backlight_device *devm_backlight_device_register(
182 struct device *dev, const char *name, struct device *parent,
183 void *devdata, const struct backlight_ops *ops,
184 const struct backlight_properties *props);
185 extern void backlight_device_unregister(struct backlight_device *bd);
186 extern void devm_backlight_device_unregister(struct device *dev,
187 struct backlight_device *bd);
188 extern void backlight_force_update(struct backlight_device *bd,
189 enum backlight_update_reason reason);
190 extern int backlight_register_notifier(struct notifier_block *nb);
191 extern int backlight_unregister_notifier(struct notifier_block *nb);
192 extern struct backlight_device *backlight_device_get_by_type(enum backlight_type type);
193 extern int backlight_device_set_brightness(struct backlight_device *bd, unsigned long brightness);
194
195 #define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)
196
bl_get_data(struct backlight_device * bl_dev)197 static inline void * bl_get_data(struct backlight_device *bl_dev)
198 {
199 return dev_get_drvdata(&bl_dev->dev);
200 }
201
202 struct generic_bl_info {
203 const char *name;
204 int max_intensity;
205 int default_intensity;
206 int limit_mask;
207 void (*set_bl_intensity)(int intensity);
208 void (*kick_battery)(void);
209 };
210
211 #ifdef CONFIG_OF
212 struct backlight_device *of_find_backlight_by_node(struct device_node *node);
213 #else
214 static inline struct backlight_device *
of_find_backlight_by_node(struct device_node * node)215 of_find_backlight_by_node(struct device_node *node)
216 {
217 return NULL;
218 }
219 #endif
220
221 #if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
222 struct backlight_device *of_find_backlight(struct device *dev);
223 struct backlight_device *devm_of_find_backlight(struct device *dev);
224 #else
of_find_backlight(struct device * dev)225 static inline struct backlight_device *of_find_backlight(struct device *dev)
226 {
227 return NULL;
228 }
229
230 static inline struct backlight_device *
devm_of_find_backlight(struct device * dev)231 devm_of_find_backlight(struct device *dev)
232 {
233 return NULL;
234 }
235 #endif
236
237 #endif
238
