4 * V4L2 file handle. Store per file handle data for the V4L2
5 * framework. Using file handles is optional for the drivers.
7 * Copyright (C) 2009--2010 Nokia Corporation.
9 * Contact: Sakari Ailus <sakari.ailus@iki.fi>
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.
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.
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
30 #include <linux/list.h>
31 #include <linux/videodev2.h>
34 struct v4l2_ctrl_handler;
37 * struct v4l2_fh - Describes a V4L2 file handler
39 * @list: list of file handlers
40 * @vdev: pointer to &struct video_device
41 * @ctrl_handler: pointer to &struct v4l2_ctrl_handler
42 * @prio: priority of the file handler, as defined by &enum v4l2_priority
44 * @wait: event' s wait queue
45 * @subscribe_lock: serialise changes to the subscribed list; guarantee that
46 * the add and del event callbacks are orderly called
47 * @subscribed: list of subscribed events
48 * @available: list of events waiting to be dequeued
49 * @navailable: number of available events at @available list
50 * @sequence: event sequence number
52 * @m2m_ctx: pointer to &struct v4l2_m2m_ctx
55 struct list_head list;
56 struct video_device *vdev;
57 struct v4l2_ctrl_handler *ctrl_handler;
58 enum v4l2_priority prio;
61 wait_queue_head_t wait;
62 struct mutex subscribe_lock;
63 struct list_head subscribed;
64 struct list_head available;
65 unsigned int navailable;
68 #if IS_ENABLED(CONFIG_V4L2_MEM2MEM_DEV)
69 struct v4l2_m2m_ctx *m2m_ctx;
74 * v4l2_fh_init - Initialise the file handle.
76 * @fh: pointer to &struct v4l2_fh
77 * @vdev: pointer to &struct video_device
79 * Parts of the V4L2 framework using the
80 * file handles should be initialised in this function. Must be called
81 * from driver's v4l2_file_operations->open\(\) handler if the driver
82 * uses &struct v4l2_fh.
84 void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev);
87 * v4l2_fh_add - Add the fh to the list of file handles on a video_device.
89 * @fh: pointer to &struct v4l2_fh
92 * The @fh file handle must be initialised first.
94 void v4l2_fh_add(struct v4l2_fh *fh);
97 * v4l2_fh_open - Ancillary routine that can be used as the open\(\) op
98 * of v4l2_file_operations.
100 * @filp: pointer to struct file
102 * It allocates a v4l2_fh and inits and adds it to the &struct video_device
103 * associated with the file pointer.
105 int v4l2_fh_open(struct file *filp);
108 * v4l2_fh_del - Remove file handle from the list of file handles.
110 * @fh: pointer to &struct v4l2_fh
112 * On error filp->private_data will be %NULL, otherwise it will point to
113 * the &struct v4l2_fh.
116 * Must be called in v4l2_file_operations->release\(\) handler if the driver
117 * uses &struct v4l2_fh.
119 void v4l2_fh_del(struct v4l2_fh *fh);
122 * v4l2_fh_exit - Release resources related to a file handle.
124 * @fh: pointer to &struct v4l2_fh
126 * Parts of the V4L2 framework using the v4l2_fh must release their
127 * resources here, too.
130 * Must be called in v4l2_file_operations->release\(\) handler if the
131 * driver uses &struct v4l2_fh.
133 void v4l2_fh_exit(struct v4l2_fh *fh);
136 * v4l2_fh_release - Ancillary routine that can be used as the release\(\) op
137 * of v4l2_file_operations.
139 * @filp: pointer to struct file
141 * It deletes and exits the v4l2_fh associated with the file pointer and
142 * frees it. It will do nothing if filp->private_data (the pointer to the
143 * v4l2_fh struct) is %NULL.
145 * This function always returns 0.
147 int v4l2_fh_release(struct file *filp);
150 * v4l2_fh_is_singular - Returns 1 if this filehandle is the only filehandle
151 * opened for the associated video_device.
153 * @fh: pointer to &struct v4l2_fh
155 * If @fh is NULL, then it returns 0.
157 int v4l2_fh_is_singular(struct v4l2_fh *fh);
160 * v4l2_fh_is_singular_file - Returns 1 if this filehandle is the only
161 * filehandle opened for the associated video_device.
163 * @filp: pointer to struct file
165 * This is a helper function variant of v4l2_fh_is_singular() with uses
166 * struct file as argument.
168 * If filp->private_data is %NULL, then it will return 0.
170 static inline int v4l2_fh_is_singular_file(struct file *filp)
172 return v4l2_fh_is_singular(filp->private_data);
175 #endif /* V4L2_EVENT_H */