1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * LCD Lowlevel Control Abstraction
4 *
5 * Copyright (C) 2003,2004 Hewlett-Packard Company
6 *
7 */
8
9 #ifndef _LINUX_LCD_H
10 #define _LINUX_LCD_H
11
12 #include <linux/device.h>
13 #include <linux/mutex.h>
14 #include <linux/notifier.h>
15 #include <linux/fb.h>
16
17 /* Notes on locking:
18 *
19 * lcd_device->ops_lock is an internal backlight lock protecting the ops
20 * field and no code outside the core should need to touch it.
21 *
22 * Access to set_power() 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_power() 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 struct lcd_device;
33 struct fb_info;
34
35 struct lcd_properties {
36 /* The maximum value for contrast (read-only) */
37 int max_contrast;
38 };
39
40 struct lcd_ops {
41 /* Get the LCD panel power status (0: full on, 1..3: controller
42 power on, flat panel power off, 4: full off), see FB_BLANK_XXX */
43 int (*get_power)(struct lcd_device *);
44 /* Enable or disable power to the LCD (0: on; 4: off, see FB_BLANK_XXX) */
45 int (*set_power)(struct lcd_device *, int power);
46 /* Get the current contrast setting (0-max_contrast) */
47 int (*get_contrast)(struct lcd_device *);
48 /* Set LCD panel contrast */
49 int (*set_contrast)(struct lcd_device *, int contrast);
50 /* Set LCD panel mode (resolutions ...) */
51 int (*set_mode)(struct lcd_device *, struct fb_videomode *);
52 /* Check if given framebuffer device is the one LCD is bound to;
53 return 0 if not, !=0 if it is. If NULL, lcd always matches the fb. */
54 int (*check_fb)(struct lcd_device *, struct fb_info *);
55 };
56
57 struct lcd_device {
58 struct lcd_properties props;
59 /* This protects the 'ops' field. If 'ops' is NULL, the driver that
60 registered this device has been unloaded, and if class_get_devdata()
61 points to something in the body of that driver, it is also invalid. */
62 struct mutex ops_lock;
63 /* If this is NULL, the backing module is unloaded */
64 const struct lcd_ops *ops;
65 /* Serialise access to set_power method */
66 struct mutex update_lock;
67 /* The framebuffer notifier block */
68 struct notifier_block fb_notif;
69
70 struct device dev;
71 };
72
73 struct lcd_platform_data {
74 /* reset lcd panel device. */
75 int (*reset)(struct lcd_device *ld);
76 /* on or off to lcd panel. if 'enable' is 0 then
77 lcd power off and 1, lcd power on. */
78 int (*power_on)(struct lcd_device *ld, int enable);
79
80 /* it indicates whether lcd panel was enabled
81 from bootloader or not. */
82 int lcd_enabled;
83 /* it means delay for stable time when it becomes low to high
84 or high to low that is dependent on whether reset gpio is
85 low active or high active. */
86 unsigned int reset_delay;
87 /* stable time needing to become lcd power on. */
88 unsigned int power_on_delay;
89 /* stable time needing to become lcd power off. */
90 unsigned int power_off_delay;
91
92 /* it could be used for any purpose. */
93 void *pdata;
94 };
95
96 static inline void lcd_set_power(struct lcd_device *ld, int power)
97 {
98 mutex_lock(&ld->update_lock);
99 if (ld->ops && ld->ops->set_power)
100 ld->ops->set_power(ld, power);
101 mutex_unlock(&ld->update_lock);
102 }
103
104 extern struct lcd_device *lcd_device_register(const char *name,
105 struct device *parent, void *devdata, const struct lcd_ops *ops);
106 extern struct lcd_device *devm_lcd_device_register(struct device *dev,
107 const char *name, struct device *parent,
108 void *devdata, const struct lcd_ops *ops);
109 extern void lcd_device_unregister(struct lcd_device *ld);
110 extern void devm_lcd_device_unregister(struct device *dev,
111 struct lcd_device *ld);
112
113 #define to_lcd_device(obj) container_of(obj, struct lcd_device, dev)
114
115 static inline void * lcd_get_data(struct lcd_device *ld_dev)
116 {
117 return dev_get_drvdata(&ld_dev->dev);
118 }
119
120
121 #endif
122
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