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
  31 struct lcd_device;
  32 struct fb_info;
  33
  34 struct lcd_properties {
  35         /* The maximum value for contrast (read-only) */
  36         int max_contrast;
  37 };
  38
  39 struct 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
  56 struct 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
  72 static 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
  80 extern struct lcd_device *lcd_device_register(const char *name,
  81         struct device *parent, void *devdata, struct lcd_ops *ops);
  82 extern void lcd_device_unregister(struct lcd_device *ld);
  83
  84 #define to_lcd_device(obj) container_of(obj, struct lcd_device, dev)
  85
  86 static inline void * lcd_get_data(struct lcd_device *ld_dev)
  87 {
  88         return dev_get_drvdata(&ld_dev->dev);
  89 }
  90
  91
  92 #endif