1/*
2 * LCD Lowlevel Control Abstraction
3 *
4 * Copyright (C) 2003,2004 Hewlett-Packard Company
5 *
6 */
7
8#ifndef _LINUX_LCD_H
9#define _LINUX_LCD_H
10
11#include <linux/device.h>
12#include <linux/mutex.h>
13#include <linux/notifier.h>
14
15/* Notes on locking:
16 *
17 * lcd_device->ops_lock is an internal backlight lock protecting the ops
18 * field and no code outside the core should need to touch it.
19 *
20 * Access to set_power() is serialised by the update_lock mutex since
21 * most drivers seem to need this and historically get it wrong.
22 *
23 * Most drivers don't need locking on their get_power() method.
24 * If yours does, you need to implement it in the driver. You can use the
25 * update_lock mutex if appropriate.
26 *
27 * Any other use of the locks below is probably wrong.
28 */
29
30struct lcd_device;
31struct fb_info;
32
33struct lcd_properties {
34	/* The maximum value for contrast (read-only) */
35	int max_contrast;
36};
37
38struct lcd_ops {
39	/* Get the LCD panel power status (0: full on, 1..3: controller
40	   power on, flat panel power off, 4: full off), see FB_BLANK_XXX */
41	int (*get_power)(struct lcd_device *);
42	/* Enable or disable power to the LCD (0: on; 4: off, see FB_BLANK_XXX) */
43	int (*set_power)(struct lcd_device *, int power);
44	/* Get the current contrast setting (0-max_contrast) */
45	int (*get_contrast)(struct lcd_device *);
46	/* Set LCD panel contrast */
47        int (*set_contrast)(struct lcd_device *, int contrast);
48	/* Check if given framebuffer device is the one LCD is bound to;
49	   return 0 if not, !=0 if it is. If NULL, lcd always matches the fb. */
50	int (*check_fb)(struct fb_info *);
51};
52
53struct lcd_device {
54	struct lcd_properties props;
55	/* This protects the 'ops' field. If 'ops' is NULL, the driver that
56	   registered this device has been unloaded, and if class_get_devdata()
57	   points to something in the body of that driver, it is also invalid. */
58	struct mutex ops_lock;
59	/* If this is NULL, the backing module is unloaded */
60	struct lcd_ops *ops;
61	/* Serialise access to set_power method */
62	struct mutex update_lock;
63	/* The framebuffer notifier block */
64	struct notifier_block fb_notif;
65	/* The class device structure */
66	struct class_device class_dev;
67};
68
69static inline void lcd_set_power(struct lcd_device *ld, int power)
70{
71	mutex_lock(&ld->update_lock);
72	if (ld->ops && ld->ops->set_power)
73		ld->ops->set_power(ld, power);
74	mutex_unlock(&ld->update_lock);
75}
76
77extern struct lcd_device *lcd_device_register(const char *name,
78	void *devdata, struct lcd_ops *ops);
79extern void lcd_device_unregister(struct lcd_device *ld);
80
81#define to_lcd_device(obj) container_of(obj, struct lcd_device, class_dev)
82
83#endif
84