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Linux/include/media/v4l2-fh.h

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  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 /**
 37  * struct v4l2_fh - Describes a V4L2 file handler
 38  *
 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
 43  *
 44  * @wait: event' s wait queue
 45  * @subscribed: list of subscribed events
 46  * @available: list of events waiting to be dequeued
 47  * @navailable: number of available events at @available list
 48  * @sequence: event sequence number
 49  * @m2m_ctx: pointer to &struct v4l2_m2m_ctx
 50  */
 51 struct v4l2_fh {
 52         struct list_head        list;
 53         struct video_device     *vdev;
 54         struct v4l2_ctrl_handler *ctrl_handler;
 55         enum v4l2_priority      prio;
 56 
 57         /* Events */
 58         wait_queue_head_t       wait;
 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  */
 80 void 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  */
 90 void 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  */
101 int 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  */
115 void 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  */
129 void 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  */
143 int 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  */
153 int 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  */
166 static 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 

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