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