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
21#ifndef V4L2_FH_H
22#define V4L2_FH_H
23
24#include <linux/fs.h>
25#include <linux/kconfig.h>
26#include <linux/list.h>
27#include <linux/videodev2.h>
28
29struct video_device;
30struct v4l2_ctrl_handler;
31
32/**
33 * struct v4l2_fh - Describes a V4L2 file handler
34 *
35 * @list: list of file handlers
36 * @vdev: pointer to &struct video_device
37 * @ctrl_handler: pointer to &struct v4l2_ctrl_handler
38 * @prio: priority of the file handler, as defined by &enum v4l2_priority
39 *
40 * @wait: event' s wait queue
41 * @subscribe_lock: serialise changes to the subscribed list; guarantee that
42 * the add and del event callbacks are orderly called
43 * @subscribed: list of subscribed events
44 * @available: list of events waiting to be dequeued
45 * @navailable: number of available events at @available list
46 * @sequence: event sequence number
47 *
48 * @m2m_ctx: pointer to &struct v4l2_m2m_ctx
49 */
50struct v4l2_fh {
51 struct list_head list;
52 struct video_device *vdev;
53 struct v4l2_ctrl_handler *ctrl_handler;
54 enum v4l2_priority prio;
55
56 /* Events */
57 wait_queue_head_t wait;
58 struct mutex subscribe_lock;
59 struct list_head subscribed;
60 struct list_head available;
61 unsigned int navailable;
62 u32 sequence;
63
64#if IS_ENABLED(CONFIG_V4L2_MEM2MEM_DEV)
65 struct v4l2_m2m_ctx *m2m_ctx;
66#endif
67};
68
69/**
70 * v4l2_fh_init - Initialise the file handle.
71 *
72 * @fh: pointer to &struct v4l2_fh
73 * @vdev: pointer to &struct video_device
74 *
75 * Parts of the V4L2 framework using the
76 * file handles should be initialised in this function. Must be called
77 * from driver's v4l2_file_operations->open\(\) handler if the driver
78 * uses &struct v4l2_fh.
79 */
80void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev);
81
82/**
83 * v4l2_fh_add - Add the fh to the list of file handles on a video_device.
84 *
85 * @fh: pointer to &struct v4l2_fh
86 *
87 * .. note::
88 * The @fh file handle must be initialised first.
89 */
90void v4l2_fh_add(struct v4l2_fh *fh);
91
92/**
93 * v4l2_fh_open - Ancillary routine that can be used as the open\(\) op
94 * of v4l2_file_operations.
95 *
96 * @filp: pointer to struct file
97 *
98 * It allocates a v4l2_fh and inits and adds it to the &struct video_device
99 * associated with the file pointer.
100 */
101int v4l2_fh_open(struct file *filp);
102
103/**
104 * v4l2_fh_del - Remove file handle from the list of file handles.
105 *
106 * @fh: pointer to &struct v4l2_fh
107 *
108 * On error filp->private_data will be %NULL, otherwise it will point to
109 * the &struct v4l2_fh.
110 *
111 * .. note::
112 * Must be called in v4l2_file_operations->release\(\) handler if the driver
113 * uses &struct v4l2_fh.
114 */
115void v4l2_fh_del(struct v4l2_fh *fh);
116
117/**
118 * v4l2_fh_exit - Release resources related to a file handle.
119 *
120 * @fh: pointer to &struct v4l2_fh
121 *
122 * Parts of the V4L2 framework using the v4l2_fh must release their
123 * resources here, too.
124 *
125 * .. note::
126 * Must be called in v4l2_file_operations->release\(\) handler if the
127 * driver uses &struct v4l2_fh.
128 */
129void v4l2_fh_exit(struct v4l2_fh *fh);
130
131/**
132 * v4l2_fh_release - Ancillary routine that can be used as the release\(\) op
133 * of v4l2_file_operations.
134 *
135 * @filp: pointer to struct file
136 *
137 * It deletes and exits the v4l2_fh associated with the file pointer and
138 * frees it. It will do nothing if filp->private_data (the pointer to the
139 * v4l2_fh struct) is %NULL.
140 *
141 * This function always returns 0.
142 */
143int v4l2_fh_release(struct file *filp);
144
145/**
146 * v4l2_fh_is_singular - Returns 1 if this filehandle is the only filehandle
147 * opened for the associated video_device.
148 *
149 * @fh: pointer to &struct v4l2_fh
150 *
151 * If @fh is NULL, then it returns 0.
152 */
153int v4l2_fh_is_singular(struct v4l2_fh *fh);
154
155/**
156 * v4l2_fh_is_singular_file - Returns 1 if this filehandle is the only
157 * filehandle opened for the associated video_device.
158 *
159 * @filp: pointer to struct file
160 *
161 * This is a helper function variant of v4l2_fh_is_singular() with uses
162 * struct file as argument.
163 *
164 * If filp->private_data is %NULL, then it will return 0.
165 */
166static inline int v4l2_fh_is_singular_file(struct file *filp)
167{
168 return v4l2_fh_is_singular(filp->private_data);
169}
170
171#endif /* V4L2_EVENT_H */
172