LXR linux/include/linux/lcd.h

   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#include <linux/fb.h>
  15
  16/* Notes on locking:
  17 *
  18 * lcd_device->ops_lock is an internal backlight lock protecting the ops
  19 * field and no code outside the core should need to touch it.
  20 *
  21 * Access to set_power() is serialised by the update_lock mutex since
  22 * most drivers seem to need this and historically get it wrong.
  23 *
  24 * Most drivers don't need locking on their get_power() method.
  25 * If yours does, you need to implement it in the driver. You can use the
  26 * update_lock mutex if appropriate.
  27 *
  28 * Any other use of the locks below is probably wrong.
  29 */
  30
  31struct lcd_device;
  32struct fb_info;
  33
  34struct lcd_properties {
  35        /* The maximum value for contrast (read-only) */
  36        int max_contrast;
  37};
  38
  39struct lcd_ops {
  40        /* Get the LCD panel power status (0: full on, 1..3: controller
  41           power on, flat panel power off, 4: full off), see FB_BLANK_XXX */
  42        int (*get_power)(struct lcd_device *);
  43        /* Enable or disable power to the LCD (0: on; 4: off, see FB_BLANK_XXX) */
  44        int (*set_power)(struct lcd_device *, int power);
  45        /* Get the current contrast setting (0-max_contrast) */
  46        int (*get_contrast)(struct lcd_device *);
  47        /* Set LCD panel contrast */
  48        int (*set_contrast)(struct lcd_device *, int contrast);
  49        /* Set LCD panel mode (resolutions ...) */
  50        int (*set_mode)(struct lcd_device *, struct fb_videomode *);
  51        /* Check if given framebuffer device is the one LCD is bound to;
  52           return 0 if not, !=0 if it is. If NULL, lcd always matches the fb. */
  53        int (*check_fb)(struct lcd_device *, struct fb_info *);
  54};
  55
  56struct lcd_device {
  57        struct lcd_properties props;
  58        /* This protects the 'ops' field. If 'ops' is NULL, the driver that
  59           registered this device has been unloaded, and if class_get_devdata()
  60           points to something in the body of that driver, it is also invalid. */
  61        struct mutex ops_lock;
  62        /* If this is NULL, the backing module is unloaded */
  63        struct lcd_ops *ops;
  64        /* Serialise access to set_power method */
  65        struct mutex update_lock;
  66        /* The framebuffer notifier block */
  67        struct notifier_block fb_notif;
  68
  69        struct device dev;
  70};
  71
  72static inline void lcd_set_power(struct lcd_device *ld, int power)
  73{
  74        mutex_lock(&ld->update_lock);
  75        if (ld->ops && ld->ops->set_power)
  76                ld->ops->set_power(ld, power);
  77        mutex_unlock(&ld->update_lock);
  78}
  79
  80extern struct lcd_device *lcd_device_register(const char *name,
  81        struct device *parent, void *devdata, struct lcd_ops *ops);
  82extern void lcd_device_unregister(struct lcd_device *ld);
  83
  84#define to_lcd_device(obj) container_of(obj, struct lcd_device, dev)
  85
  86static inline void * lcd_get_data(struct lcd_device *ld_dev)
  87{
  88        return dev_get_drvdata(&ld_dev->dev);
  89}
  90
  91
  92#endif
  93