1/*
  2 * v4l2-fh.h
  3 *
  4 * V4L2 file handle. Store per file handle data for the V4L2
  5 * framework. Using file handles is optional for the drivers.
  6 *
  7 * Copyright (C) 2009--2010 Nokia Corporation.
  8 *
  9 * Contact: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
 10 *
 11 * This program is free software; you can redistribute it and/or
 12 * modify it under the terms of the GNU General Public License
 13 * version 2 as published by the Free Software Foundation.
 14 *
 15 * This program is distributed in the hope that it will be useful, but
 16 * WITHOUT ANY WARRANTY; without even the implied warranty of
 17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 18 * General Public License for more details.
 19 *
 20 * You should have received a copy of the GNU General Public License
 21 * along with this program; if not, write to the Free Software
 22 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 23 * 02110-1301 USA
 24 */
 25
 26#ifndef V4L2_FH_H
 27#define V4L2_FH_H
 28
 29#include <linux/list.h>
 30
 31struct video_device;
 32struct v4l2_ctrl_handler;
 33
 34struct v4l2_fh {
 35	struct list_head	list;
 36	struct video_device	*vdev;
 37	struct v4l2_ctrl_handler *ctrl_handler;
 38	enum v4l2_priority	prio;
 39
 40	/* Events */
 41	wait_queue_head_t	wait;
 42	struct list_head	subscribed; /* Subscribed events */
 43	struct list_head	available; /* Dequeueable event */
 44	unsigned int		navailable;
 45	u32			sequence;
 46};
 47
 48/*
 49 * Initialise the file handle. Parts of the V4L2 framework using the
 50 * file handles should be initialised in this function. Must be called
 51 * from driver's v4l2_file_operations->open() handler if the driver
 52 * uses v4l2_fh.
 53 */
 54void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev);
 55/*
 56 * Add the fh to the list of file handles on a video_device. The file
 57 * handle must be initialised first.
 58 */
 59void v4l2_fh_add(struct v4l2_fh *fh);
 60/*
 61 * Can be used as the open() op of v4l2_file_operations.
 62 * It allocates a v4l2_fh and inits and adds it to the video_device associated
 63 * with the file pointer.
 64 */
 65int v4l2_fh_open(struct file *filp);
 66/*
 67 * Remove file handle from the list of file handles. Must be called in
 68 * v4l2_file_operations->release() handler if the driver uses v4l2_fh.
 69 * On error filp->private_data will be NULL, otherwise it will point to
 70 * the v4l2_fh struct.
 71 */
 72void v4l2_fh_del(struct v4l2_fh *fh);
 73/*
 74 * Release resources related to a file handle. Parts of the V4L2
 75 * framework using the v4l2_fh must release their resources here, too.
 76 * Must be called in v4l2_file_operations->release() handler if the
 77 * driver uses v4l2_fh.
 78 */
 79void v4l2_fh_exit(struct v4l2_fh *fh);
 80/*
 81 * Can be used as the release() op of v4l2_file_operations.
 82 * It deletes and exits the v4l2_fh associated with the file pointer and
 83 * frees it. It will do nothing if filp->private_data (the pointer to the
 84 * v4l2_fh struct) is NULL. This function always returns 0.
 85 */
 86int v4l2_fh_release(struct file *filp);
 87/*
 88 * Returns 1 if this filehandle is the only filehandle opened for the
 89 * associated video_device. If fh is NULL, then it returns 0.
 90 */
 91int v4l2_fh_is_singular(struct v4l2_fh *fh);
 92/*
 93 * Helper function with struct file as argument. If filp->private_data is
 94 * NULL, then it will return 0.
 95 */
 96static inline int v4l2_fh_is_singular_file(struct file *filp)
 97{
 98	return v4l2_fh_is_singular(filp->private_data);
 99}
100
101#endif /* V4L2_EVENT_H */