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  * 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
  23  * 02110-1301 USA
  24  */
  25
  26 #ifndef V4L2_FH_H
  27 #define V4L2_FH_H
  28
  29 #include <linux/fs.h>
  30 #include <linux/list.h>
  31 #include <linux/videodev2.h>
  32
  33 struct video_device;
  34 struct v4l2_ctrl_handler;
  35
  36 struct v4l2_fh {
  37         struct list_head        list;
  38         struct video_device     *vdev;
  39         struct v4l2_ctrl_handler *ctrl_handler;
  40         enum v4l2_priority      prio;
  41
  42         /* Events */
  43         wait_queue_head_t       wait;
  44         struct list_head        subscribed; /* Subscribed events */
  45         struct list_head        available; /* Dequeueable event */
  46         unsigned int            navailable;
  47         u32                     sequence;
  48
  49 #if IS_ENABLED(CONFIG_V4L2_MEM2MEM_DEV)
  50         struct v4l2_m2m_ctx     *m2m_ctx;
  51 #endif
  52 };
  53
  54 /*
  55  * Initialise the file handle. Parts of the V4L2 framework using the
  56  * file handles should be initialised in this function. Must be called
  57  * from driver's v4l2_file_operations->open() handler if the driver
  58  * uses v4l2_fh.
  59  */
  60 void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev);
  61 /*
  62  * Add the fh to the list of file handles on a video_device. The file
  63  * handle must be initialised first.
  64  */
  65 void v4l2_fh_add(struct v4l2_fh *fh);
  66 /*
  67  * Can be used as the open() op of v4l2_file_operations.
  68  * It allocates a v4l2_fh and inits and adds it to the video_device associated
  69  * with the file pointer.
  70  */
  71 int v4l2_fh_open(struct file *filp);
  72 /*
  73  * Remove file handle from the list of file handles. Must be called in
  74  * v4l2_file_operations->release() handler if the driver uses v4l2_fh.
  75  * On error filp->private_data will be NULL, otherwise it will point to
  76  * the v4l2_fh struct.
  77  */
  78 void v4l2_fh_del(struct v4l2_fh *fh);
  79 /*
  80  * Release resources related to a file handle. Parts of the V4L2
  81  * framework using the v4l2_fh must release their resources here, too.
  82  * Must be called in v4l2_file_operations->release() handler if the
  83  * driver uses v4l2_fh.
  84  */
  85 void v4l2_fh_exit(struct v4l2_fh *fh);
  86 /*
  87  * Can be used as the release() op of v4l2_file_operations.
  88  * It deletes and exits the v4l2_fh associated with the file pointer and
  89  * frees it. It will do nothing if filp->private_data (the pointer to the
  90  * v4l2_fh struct) is NULL. This function always returns 0.
  91  */
  92 int v4l2_fh_release(struct file *filp);
  93 /*
  94  * Returns 1 if this filehandle is the only filehandle opened for the
  95  * associated video_device. If fh is NULL, then it returns 0.
  96  */
  97 int v4l2_fh_is_singular(struct v4l2_fh *fh);
  98 /*
  99  * Helper function with struct file as argument. If filp->private_data is
 100  * NULL, then it will return 0.
 101  */
 102 static inline int v4l2_fh_is_singular_file(struct file *filp)
 103 {
 104         return v4l2_fh_is_singular(filp->private_data);
 105 }
 106
 107 #endif /* V4L2_EVENT_H */