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v4l2-fh.h
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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 <[email protected]>
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 
31 struct video_device;
32 struct v4l2_ctrl_handler;
33 
34 struct v4l2_fh {
35  struct list_head list;
36  struct video_device *vdev;
39 
40  /* Events */
42  struct list_head subscribed; /* Subscribed events */
43  struct list_head available; /* Dequeueable event */
44  unsigned int navailable;
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  */
54 void 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  */
59 void 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  */
65 int 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  */
72 void 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  */
79 void 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  */
86 int 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  */
91 int 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  */
96 static 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 */