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 struct backlight_device;
50 struct fb_info;
51 
52 struct 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 */
68 struct 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 	unsigned int state;
83 
84 #define BL_CORE_SUSPENDED	(1 << 0)	/* backlight is suspended */
85 #define BL_CORE_FBBLANK		(1 << 1)	/* backlight is under an fb blank event */
86 
87 };
88 
89 struct backlight_device {
90 	/* Backlight properties */
91 	struct backlight_properties props;
92 
93 	/* Serialise access to update_status method */
94 	struct mutex update_lock;
95 
96 	/* This protects the 'ops' field. If 'ops' is NULL, the driver that
97 	   registered this device has been unloaded, and if class_get_devdata()
98 	   points to something in the body of that driver, it is also invalid. */
99 	struct mutex ops_lock;
100 	const struct backlight_ops *ops;
101 
102 	/* The framebuffer notifier block */
103 	struct notifier_block fb_notif;
104 
105 	/* list entry of all registered backlight devices */
106 	struct list_head entry;
107 
108 	struct device dev;
109 
110 	/* Multiple framebuffers may share one backlight device */
111 	bool fb_bl_on[FB_MAX];
112 
113 	int use_count;
114 };
115 
backlight_update_status(struct backlight_device * bd)116 static inline int backlight_update_status(struct backlight_device *bd)
117 {
118 	int ret = -ENOENT;
119 
120 	mutex_lock(&bd->update_lock);
121 	if (bd->ops && bd->ops->update_status)
122 		ret = bd->ops->update_status(bd);
123 	mutex_unlock(&bd->update_lock);
124 
125 	return ret;
126 }
127 
128 /**
129  * backlight_enable - Enable backlight
130  * @bd: the backlight device to enable
131  */
backlight_enable(struct backlight_device * bd)132 static inline int backlight_enable(struct backlight_device *bd)
133 {
134 	if (!bd)
135 		return 0;
136 
137 	bd->props.power = FB_BLANK_UNBLANK;
138 	bd->props.fb_blank = FB_BLANK_UNBLANK;
139 	bd->props.state &= ~BL_CORE_FBBLANK;
140 
141 	return backlight_update_status(bd);
142 }
143 
144 /**
145  * backlight_disable - Disable backlight
146  * @bd: the backlight device to disable
147  */
backlight_disable(struct backlight_device * bd)148 static inline int backlight_disable(struct backlight_device *bd)
149 {
150 	if (!bd)
151 		return 0;
152 
153 	bd->props.power = FB_BLANK_POWERDOWN;
154 	bd->props.fb_blank = FB_BLANK_POWERDOWN;
155 	bd->props.state |= BL_CORE_FBBLANK;
156 
157 	return backlight_update_status(bd);
158 }
159 
160 /**
161  * backlight_put - Drop backlight reference
162  * @bd: the backlight device to put
163  */
backlight_put(struct backlight_device * bd)164 static inline void backlight_put(struct backlight_device *bd)
165 {
166 	if (bd)
167 		put_device(&bd->dev);
168 }
169 
170 extern struct backlight_device *backlight_device_register(const char *name,
171 	struct device *dev, void *devdata, const struct backlight_ops *ops,
172 	const struct backlight_properties *props);
173 extern struct backlight_device *devm_backlight_device_register(
174 	struct device *dev, const char *name, struct device *parent,
175 	void *devdata, const struct backlight_ops *ops,
176 	const struct backlight_properties *props);
177 extern void backlight_device_unregister(struct backlight_device *bd);
178 extern void devm_backlight_device_unregister(struct device *dev,
179 					struct backlight_device *bd);
180 extern void backlight_force_update(struct backlight_device *bd,
181 				   enum backlight_update_reason reason);
182 extern int backlight_register_notifier(struct notifier_block *nb);
183 extern int backlight_unregister_notifier(struct notifier_block *nb);
184 extern struct backlight_device *backlight_device_get_by_type(enum backlight_type type);
185 extern int backlight_device_set_brightness(struct backlight_device *bd, unsigned long brightness);
186 
187 #define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)
188 
bl_get_data(struct backlight_device * bl_dev)189 static inline void * bl_get_data(struct backlight_device *bl_dev)
190 {
191 	return dev_get_drvdata(&bl_dev->dev);
192 }
193 
194 struct generic_bl_info {
195 	const char *name;
196 	int max_intensity;
197 	int default_intensity;
198 	int limit_mask;
199 	void (*set_bl_intensity)(int intensity);
200 	void (*kick_battery)(void);
201 };
202 
203 #ifdef CONFIG_OF
204 struct backlight_device *of_find_backlight_by_node(struct device_node *node);
205 #else
206 static inline struct backlight_device *
of_find_backlight_by_node(struct device_node * node)207 of_find_backlight_by_node(struct device_node *node)
208 {
209 	return NULL;
210 }
211 #endif
212 
213 #if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
214 struct backlight_device *of_find_backlight(struct device *dev);
215 struct backlight_device *devm_of_find_backlight(struct device *dev);
216 #else
of_find_backlight(struct device * dev)217 static inline struct backlight_device *of_find_backlight(struct device *dev)
218 {
219 	return NULL;
220 }
221 
222 static inline struct backlight_device *
devm_of_find_backlight(struct device * dev)223 devm_of_find_backlight(struct device *dev)
224 {
225 	return NULL;
226 }
227 #endif
228 
229 #endif
230