1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * v4l2-fh.h
4 *
5 * V4L2 file handle. Store per file handle data for the V4L2
6 * framework. Using file handles is optional for the drivers.
7 *
8 * Copyright (C) 2009--2010 Nokia Corporation.
9 *
10 * Contact: Sakari Ailus <sakari.ailus@iki.fi>
11 */
12
13 #ifndef V4L2_FH_H
14 #define V4L2_FH_H
15
16 #include <linux/fs.h>
17 #include <linux/kconfig.h>
18 #include <linux/list.h>
19 #include <linux/videodev2.h>
20
21 struct video_device;
22 struct v4l2_ctrl_handler;
23
24 /**
25 * struct v4l2_fh - Describes a V4L2 file handler
26 *
27 * @list: list of file handlers
28 * @vdev: pointer to &struct video_device
29 * @ctrl_handler: pointer to &struct v4l2_ctrl_handler
30 * @prio: priority of the file handler, as defined by &enum v4l2_priority
31 *
32 * @wait: event' s wait queue
33 * @subscribe_lock: serialise changes to the subscribed list; guarantee that
34 * the add and del event callbacks are orderly called
35 * @subscribed: list of subscribed events
36 * @available: list of events waiting to be dequeued
37 * @navailable: number of available events at @available list
38 * @sequence: event sequence number
39 *
40 * @m2m_ctx: pointer to &struct v4l2_m2m_ctx
41 */
42 struct v4l2_fh {
43 struct list_head list;
44 struct video_device *vdev;
45 struct v4l2_ctrl_handler *ctrl_handler;
46 enum v4l2_priority prio;
47
48 /* Events */
49 wait_queue_head_t wait;
50 struct mutex subscribe_lock;
51 struct list_head subscribed;
52 struct list_head available;
53 unsigned int navailable;
54 u32 sequence;
55
56 #if IS_ENABLED(CONFIG_V4L2_MEM2MEM_DEV)
57 struct v4l2_m2m_ctx *m2m_ctx;
58 #endif
59 };
60
61 /**
62 * v4l2_fh_init - Initialise the file handle.
63 *
64 * @fh: pointer to &struct v4l2_fh
65 * @vdev: pointer to &struct video_device
66 *
67 * Parts of the V4L2 framework using the
68 * file handles should be initialised in this function. Must be called
69 * from driver's v4l2_file_operations->open\(\) handler if the driver
70 * uses &struct v4l2_fh.
71 */
72 void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev);
73
74 /**
75 * v4l2_fh_add - Add the fh to the list of file handles on a video_device.
76 *
77 * @fh: pointer to &struct v4l2_fh
78 *
79 * .. note::
80 * The @fh file handle must be initialised first.
81 */
82 void v4l2_fh_add(struct v4l2_fh *fh);
83
84 /**
85 * v4l2_fh_open - Ancillary routine that can be used as the open\(\) op
86 * of v4l2_file_operations.
87 *
88 * @filp: pointer to struct file
89 *
90 * It allocates a v4l2_fh and inits and adds it to the &struct video_device
91 * associated with the file pointer.
92 */
93 int v4l2_fh_open(struct file *filp);
94
95 /**
96 * v4l2_fh_del - Remove file handle from the list of file handles.
97 *
98 * @fh: pointer to &struct v4l2_fh
99 *
100 * On error filp->private_data will be %NULL, otherwise it will point to
101 * the &struct v4l2_fh.
102 *
103 * .. note::
104 * Must be called in v4l2_file_operations->release\(\) handler if the driver
105 * uses &struct v4l2_fh.
106 */
107 void v4l2_fh_del(struct v4l2_fh *fh);
108
109 /**
110 * v4l2_fh_exit - Release resources related to a file handle.
111 *
112 * @fh: pointer to &struct v4l2_fh
113 *
114 * Parts of the V4L2 framework using the v4l2_fh must release their
115 * resources here, too.
116 *
117 * .. note::
118 * Must be called in v4l2_file_operations->release\(\) handler if the
119 * driver uses &struct v4l2_fh.
120 */
121 void v4l2_fh_exit(struct v4l2_fh *fh);
122
123 /**
124 * v4l2_fh_release - Ancillary routine that can be used as the release\(\) op
125 * of v4l2_file_operations.
126 *
127 * @filp: pointer to struct file
128 *
129 * It deletes and exits the v4l2_fh associated with the file pointer and
130 * frees it. It will do nothing if filp->private_data (the pointer to the
131 * v4l2_fh struct) is %NULL.
132 *
133 * This function always returns 0.
134 */
135 int v4l2_fh_release(struct file *filp);
136
137 /**
138 * v4l2_fh_is_singular - Returns 1 if this filehandle is the only filehandle
139 * opened for the associated video_device.
140 *
141 * @fh: pointer to &struct v4l2_fh
142 *
143 * If @fh is NULL, then it returns 0.
144 */
145 int v4l2_fh_is_singular(struct v4l2_fh *fh);
146
147 /**
148 * v4l2_fh_is_singular_file - Returns 1 if this filehandle is the only
149 * filehandle opened for the associated video_device.
150 *
151 * @filp: pointer to struct file
152 *
153 * This is a helper function variant of v4l2_fh_is_singular() with uses
154 * struct file as argument.
155 *
156 * If filp->private_data is %NULL, then it will return 0.
157 */
158 static inline int v4l2_fh_is_singular_file(struct file *filp)
159 {
160 return v4l2_fh_is_singular(filp->private_data);
161 }
162
163 #endif /* V4L2_EVENT_H */