xref: /openbmc/linux/include/linux/lcd.h (revision e7642f35)
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 	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 
lcd_set_power(struct lcd_device * ld,int power)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, 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, 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 
lcd_get_data(struct lcd_device * ld_dev)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