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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>
28ee086d 12#include <linux/mutex.h>
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13#include <linux/notifier.h>
14
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15/* Notes on locking:
16 *
599a52d1 17 * lcd_device->ops_lock is an internal backlight lock protecting the ops
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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
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30struct lcd_device;
31struct fb_info;
32
1da177e4 33struct lcd_properties {
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34 /* The maximum value for contrast (read-only) */
35 int max_contrast;
36};
37
38struct lcd_ops {
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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);
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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 {
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54 struct lcd_properties props;
55 /* This protects the 'ops' field. If 'ops' is NULL, the driver that
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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. */
599a52d1 58 struct mutex ops_lock;
1da177e4 59 /* If this is NULL, the backing module is unloaded */
599a52d1 60 struct lcd_ops *ops;
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61 /* Serialise access to set_power method */
62 struct mutex update_lock;
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63 /* The framebuffer notifier block */
64 struct notifier_block fb_notif;
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65
66 struct device dev;
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67};
68
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69static inline void lcd_set_power(struct lcd_device *ld, int power)
70{
71 mutex_lock(&ld->update_lock);
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72 if (ld->ops && ld->ops->set_power)
73 ld->ops->set_power(ld, power);
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74 mutex_unlock(&ld->update_lock);
75}
76
1da177e4 77extern struct lcd_device *lcd_device_register(const char *name,
655bfd7a 78 struct device *parent, void *devdata, struct lcd_ops *ops);
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79extern void lcd_device_unregister(struct lcd_device *ld);
80
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81#define to_lcd_device(obj) container_of(obj, struct lcd_device, dev)
82
83static inline void * lcd_get_data(struct lcd_device *ld_dev)
84{
85 return dev_get_drvdata(&ld_dev->dev);
86}
87
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88
89#endif