/*
   * v4l2-fh.h
   *
   * V4L2 file handle. Store per file handle data for the V4L2
   * framework. Using file handles is optional for the drivers.
   *
   * Copyright (C) 2009--2010 Nokia Corporation.
   *
   * Contact: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License
   * version 2 as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
   * 02110-1301 USA
   */
  
  #ifndef V4L2_FH_H
  #define V4L2_FH_H
  
  #include <linux/list.h>
  
  struct video_device;

  struct v4l2_ctrl_handler;

  
  struct v4l2_fh {
  	struct list_head	list;
  	struct video_device	*vdev;

  	struct v4l2_ctrl_handler *ctrl_handler;

  	enum v4l2_priority	prio;

  
  	/* Events */
  	wait_queue_head_t	wait;
  	struct list_head	subscribed; /* Subscribed events */

  	struct list_head	available; /* Dequeueable event */
  	unsigned int		navailable;

  	u32			sequence;

  };
  
  /*
   * Initialise the file handle. Parts of the V4L2 framework using the
   * file handles should be initialised in this function. Must be called
   * from driver's v4l2_file_operations->open() handler if the driver
   * uses v4l2_fh.
   */

  void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev);

  /*
   * Add the fh to the list of file handles on a video_device. The file
   * handle must be initialised first.
   */
  void v4l2_fh_add(struct v4l2_fh *fh);
  /*

   * Can be used as the open() op of v4l2_file_operations.
   * It allocates a v4l2_fh and inits and adds it to the video_device associated
   * with the file pointer.
   */
  int v4l2_fh_open(struct file *filp);
  /*

   * Remove file handle from the list of file handles. Must be called in
   * v4l2_file_operations->release() handler if the driver uses v4l2_fh.

   * On error filp->private_data will be NULL, otherwise it will point to
   * the v4l2_fh struct.

   */
  void v4l2_fh_del(struct v4l2_fh *fh);
  /*
   * Release resources related to a file handle. Parts of the V4L2
   * framework using the v4l2_fh must release their resources here, too.
   * Must be called in v4l2_file_operations->release() handler if the
   * driver uses v4l2_fh.
   */
  void v4l2_fh_exit(struct v4l2_fh *fh);

  /*
   * Can be used as the release() op of v4l2_file_operations.
   * It deletes and exits the v4l2_fh associated with the file pointer and
   * frees it. It will do nothing if filp->private_data (the pointer to the
   * v4l2_fh struct) is NULL. This function always returns 0.
   */
  int v4l2_fh_release(struct file *filp);

  /*
   * Returns 1 if this filehandle is the only filehandle opened for the
   * associated video_device. If fh is NULL, then it returns 0.
   */
  int v4l2_fh_is_singular(struct v4l2_fh *fh);
  /*
   * Helper function with struct file as argument. If filp->private_data is
   * NULL, then it will return 0.
   */
  static inline int v4l2_fh_is_singular_file(struct file *filp)
  {
  	return v4l2_fh_is_singular(filp->private_data);
  }

  
  #endif /* V4L2_EVENT_H */