LXR linux/include/media/v4l2-fh.h

   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