v4l2-fh.h revision 8e6e8f93f7cb3452b1c00da8a30d01558628d913 
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@iki.fi>
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/fs.h>
30#include <linux/list.h>
31#include <linux/videodev2.h>
32
33struct video_device;
34struct v4l2_ctrl_handler;
35
36struct v4l2_fh {
37	struct list_head	list;
38	struct video_device	*vdev;
39	struct v4l2_ctrl_handler *ctrl_handler;
40	enum v4l2_priority	prio;
41
42	/* Events */
43	wait_queue_head_t	wait;
44	struct list_head	subscribed; /* Subscribed events */
45	struct list_head	available; /* Dequeueable event */
46	unsigned int		navailable;
47	u32			sequence;
48
49#if IS_ENABLED(CONFIG_V4L2_MEM2MEM_DEV)
50	struct v4l2_m2m_ctx	*m2m_ctx;
51#endif
52};
53
54/*
55 * Initialise the file handle. Parts of the V4L2 framework using the
56 * file handles should be initialised in this function. Must be called
57 * from driver's v4l2_file_operations->open() handler if the driver
58 * uses v4l2_fh.
59 */
60void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev);
61/*
62 * Add the fh to the list of file handles on a video_device. The file
63 * handle must be initialised first.
64 */
65void v4l2_fh_add(struct v4l2_fh *fh);
66/*
67 * Can be used as the open() op of v4l2_file_operations.
68 * It allocates a v4l2_fh and inits and adds it to the video_device associated
69 * with the file pointer.
70 */
71int v4l2_fh_open(struct file *filp);
72/*
73 * Remove file handle from the list of file handles. Must be called in
74 * v4l2_file_operations->release() handler if the driver uses v4l2_fh.
75 * On error filp->private_data will be NULL, otherwise it will point to
76 * the v4l2_fh struct.
77 */
78void v4l2_fh_del(struct v4l2_fh *fh);
79/*
80 * Release resources related to a file handle. Parts of the V4L2
81 * framework using the v4l2_fh must release their resources here, too.
82 * Must be called in v4l2_file_operations->release() handler if the
83 * driver uses v4l2_fh.
84 */
85void v4l2_fh_exit(struct v4l2_fh *fh);
86/*
87 * Can be used as the release() op of v4l2_file_operations.
88 * It deletes and exits the v4l2_fh associated with the file pointer and
89 * frees it. It will do nothing if filp->private_data (the pointer to the
90 * v4l2_fh struct) is NULL. This function always returns 0.
91 */
92int v4l2_fh_release(struct file *filp);
93/*
94 * Returns 1 if this filehandle is the only filehandle opened for the
95 * associated video_device. If fh is NULL, then it returns 0.
96 */
97int v4l2_fh_is_singular(struct v4l2_fh *fh);
98/*
99 * Helper function with struct file as argument. If filp->private_data is
100 * NULL, then it will return 0.
101 */
102static inline int v4l2_fh_is_singular_file(struct file *filp)
103{
104	return v4l2_fh_is_singular(filp->private_data);
105}
106
107#endif /* V4L2_EVENT_H */
108