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