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 29 struct video_device; 30 struct 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 */ 50 struct 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 */ 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