/*
   * Backlight Lowlevel Control Abstraction
   *
   * Copyright (C) 2003,2004 Hewlett-Packard Company
   *
   */
  
  #ifndef _LINUX_BACKLIGHT_H
  #define _LINUX_BACKLIGHT_H
  
  #include <linux/device.h>

  #include <linux/fb.h>

  #include <linux/mutex.h>

  #include <linux/notifier.h>

  /* Notes on locking:
   *

   * backlight_device->ops_lock is an internal backlight lock protecting the
   * ops pointer and no code outside the core should need to touch it.

   *
   * Access to update_status() is serialised by the update_lock mutex since
   * most drivers seem to need this and historically get it wrong.
   *
   * Most drivers don't need locking on their get_brightness() method.
   * If yours does, you need to implement it in the driver. You can use the
   * update_lock mutex if appropriate.
   *
   * Any other use of the locks below is probably wrong.
   */

  enum backlight_update_reason {
  	BACKLIGHT_UPDATE_HOTKEY,
  	BACKLIGHT_UPDATE_SYSFS,
  };

  enum backlight_type {
  	BACKLIGHT_RAW = 1,
  	BACKLIGHT_PLATFORM,
  	BACKLIGHT_FIRMWARE,
  	BACKLIGHT_TYPE_MAX,
  };

  enum backlight_notification {
  	BACKLIGHT_REGISTERED,
  	BACKLIGHT_UNREGISTERED,
  };

  struct backlight_device;
  struct fb_info;

  struct backlight_ops {

  	unsigned int options;

  
  #define BL_CORE_SUSPENDRESUME	(1 << 0)

  	/* Notify the backlight driver some property has changed */

  	int (*update_status)(struct backlight_device *);

  	/* Return the current backlight brightness (accounting for power,
  	   fb_blank etc.) */

  	int (*get_brightness)(struct backlight_device *);

  	/* Check if given framebuffer device is the one bound to this backlight;
  	   return 0 if not, !=0 if it is. If NULL, backlight always matches the fb. */

  	int (*check_fb)(struct backlight_device *, struct fb_info *);

  };

  /* This structure defines all the properties of a backlight */
  struct backlight_properties {

  	/* Current User requested brightness (0 - max_brightness) */
  	int brightness;
  	/* Maximal value for brightness (read-only) */
  	int max_brightness;
  	/* Current FB Power mode (0: full on, 1..3: power saving
  	   modes; 4: full off), see FB_BLANK_XXX */
  	int power;
  	/* FB Blanking active? (values as for power) */

  	/* Due to be removed, please use (state & BL_CORE_FBBLANK) */

  	int fb_blank;

  	/* Backlight type */
  	enum backlight_type type;

  	/* Flags used to signal drivers of state changes */
  	/* Upper 4 bits are reserved for driver internal use */
  	unsigned int state;
  
  #define BL_CORE_SUSPENDED	(1 << 0)	/* backlight is suspended */
  #define BL_CORE_FBBLANK		(1 << 1)	/* backlight is under an fb blank event */
  #define BL_CORE_DRIVER4		(1 << 28)	/* reserved for driver specific use */
  #define BL_CORE_DRIVER3		(1 << 29)	/* reserved for driver specific use */
  #define BL_CORE_DRIVER2		(1 << 30)	/* reserved for driver specific use */
  #define BL_CORE_DRIVER1		(1 << 31)	/* reserved for driver specific use */

  };
  
  struct backlight_device {

  	/* Backlight properties */
  	struct backlight_properties props;

  	/* Serialise access to update_status method */
  	struct mutex update_lock;

  
  	/* This protects the 'ops' field. If 'ops' is NULL, the driver that
  	   registered this device has been unloaded, and if class_get_devdata()
  	   points to something in the body of that driver, it is also invalid. */
  	struct mutex ops_lock;

  	const struct backlight_ops *ops;

  	/* The framebuffer notifier block */
  	struct notifier_block fb_notif;

  	/* list entry of all registered backlight devices */
  	struct list_head entry;

  	struct device dev;

  
  	/* Multiple framebuffers may share one backlight device */
  	bool fb_bl_on[FB_MAX];
  
  	int use_count;

  };

  static inline int backlight_update_status(struct backlight_device *bd)

  {

  	int ret = -ENOENT;

  	mutex_lock(&bd->update_lock);

  	if (bd->ops && bd->ops->update_status)

  		ret = bd->ops->update_status(bd);

  	mutex_unlock(&bd->update_lock);

  
  	return ret;

  }

  extern struct backlight_device *backlight_device_register(const char *name,

  	struct device *dev, void *devdata, const struct backlight_ops *ops,
  	const struct backlight_properties *props);

  extern struct backlight_device *devm_backlight_device_register(
  	struct device *dev, const char *name, struct device *parent,
  	void *devdata, const struct backlight_ops *ops,
  	const struct backlight_properties *props);

  extern void backlight_device_unregister(struct backlight_device *bd);

  extern void devm_backlight_device_unregister(struct device *dev,
  					struct backlight_device *bd);

  extern void backlight_force_update(struct backlight_device *bd,
  				   enum backlight_update_reason reason);

  extern bool backlight_device_registered(enum backlight_type type);

  extern int backlight_register_notifier(struct notifier_block *nb);
  extern int backlight_unregister_notifier(struct notifier_block *nb);

  #define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)
  
  static inline void * bl_get_data(struct backlight_device *bl_dev)
  {
  	return dev_get_drvdata(&bl_dev->dev);
  }

  struct generic_bl_info {
  	const char *name;
  	int max_intensity;
  	int default_intensity;
  	int limit_mask;
  	void (*set_bl_intensity)(int intensity);
  	void (*kick_battery)(void);
  };

  #ifdef CONFIG_OF
  struct backlight_device *of_find_backlight_by_node(struct device_node *node);
  #else
  static inline struct backlight_device *
  of_find_backlight_by_node(struct device_node *node)
  {
  	return NULL;
  }
  #endif

  #endif