1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 /* 3 * v4l2-fh.h 4 * 5 * V4L2 file handle. Store per file handle data for the V4L2 6 * framework. Using file handles is mandatory for the drivers. 7 * 8 * Copyright (C) 2009--2010 Nokia Corporation. 9 * 10 * Contact: Sakari Ailus <sakari.ailus@iki.fi> 11 */ 12 13 #ifndef V4L2_FH_H 14 #define V4L2_FH_H 15 16 #include <linux/fs.h> 17 #include <linux/kconfig.h> 18 #include <linux/list.h> 19 #include <linux/videodev2.h> 20 21 struct video_device; 22 struct v4l2_ctrl_handler; 23 24 /** 25 * struct v4l2_fh - Describes a V4L2 file handler 26 * 27 * @list: list of file handlers 28 * @vdev: pointer to &struct video_device 29 * @ctrl_handler: pointer to &struct v4l2_ctrl_handler 30 * @prio: priority of the file handler, as defined by &enum v4l2_priority 31 * 32 * @wait: event' s wait queue 33 * @subscribe_lock: serialise changes to the subscribed list; guarantee that 34 * the add and del event callbacks are orderly called 35 * @subscribed: list of subscribed events 36 * @available: list of events waiting to be dequeued 37 * @navailable: number of available events at @available list 38 * @sequence: event sequence number 39 * 40 * @m2m_ctx: pointer to &struct v4l2_m2m_ctx 41 */ 42 struct v4l2_fh { 43 struct list_head list; 44 struct video_device *vdev; 45 struct v4l2_ctrl_handler *ctrl_handler; 46 enum v4l2_priority prio; 47 48 /* Events */ 49 wait_queue_head_t wait; 50 struct mutex subscribe_lock; 51 struct list_head subscribed; 52 struct list_head available; 53 unsigned int navailable; 54 u32 sequence; 55 56 struct v4l2_m2m_ctx *m2m_ctx; 57 }; 58 59 /** 60 * file_to_v4l2_fh - Return the v4l2_fh associated with a struct file 61 * 62 * @filp: pointer to &struct file 63 * 64 * This function should be used by drivers to retrieve the &struct v4l2_fh 65 * instance pointer stored in the file private_data instead of accessing the 66 * private_data field directly. 67 */ 68 static inline struct v4l2_fh *file_to_v4l2_fh(struct file *filp) 69 { 70 return filp->private_data; 71 } 72 73 /** 74 * v4l2_fh_init - Initialise the file handle. 75 * 76 * @fh: pointer to &struct v4l2_fh 77 * @vdev: pointer to &struct video_device 78 * 79 * Parts of the V4L2 framework using the 80 * file handles should be initialised in this function. Must be called 81 * from driver's v4l2_file_operations->open\(\) handler if the driver 82 * uses &struct v4l2_fh. 83 */ 84 void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev); 85 86 /** 87 * v4l2_fh_add - Add the fh to the list of file handles on a video_device. 88 * 89 * @fh: pointer to &struct v4l2_fh 90 * @filp: pointer to &struct file associated with @fh 91 * 92 * The function sets filp->private_data to point to @fh. 93 * 94 * .. note:: 95 * The @fh file handle must be initialised first. 96 */ 97 void v4l2_fh_add(struct v4l2_fh *fh, struct file *filp); 98 99 /** 100 * v4l2_fh_open - Ancillary routine that can be used as the open\(\) op 101 * of v4l2_file_operations. 102 * 103 * @filp: pointer to struct file 104 * 105 * It allocates a v4l2_fh and inits and adds it to the &struct video_device 106 * associated with the file pointer. 107 * 108 * On error filp->private_data will be %NULL, otherwise it will point to 109 * the &struct v4l2_fh. 110 */ 111 int v4l2_fh_open(struct file *filp); 112 113 /** 114 * v4l2_fh_del - Remove file handle from the list of file handles. 115 * 116 * @fh: pointer to &struct v4l2_fh 117 * @filp: pointer to &struct file associated with @fh 118 * 119 * The function resets filp->private_data to NULL. 120 * 121 * .. note:: 122 * Must be called in v4l2_file_operations->release\(\) handler if the driver 123 * uses &struct v4l2_fh. 124 */ 125 void v4l2_fh_del(struct v4l2_fh *fh, struct file *filp); 126 127 /** 128 * v4l2_fh_exit - Release resources related to a file handle. 129 * 130 * @fh: pointer to &struct v4l2_fh 131 * 132 * Parts of the V4L2 framework using the v4l2_fh must release their 133 * resources here, too. 134 * 135 * .. note:: 136 * Must be called in v4l2_file_operations->release\(\) handler if the 137 * driver uses &struct v4l2_fh. 138 */ 139 void v4l2_fh_exit(struct v4l2_fh *fh); 140 141 /** 142 * v4l2_fh_release - Ancillary routine that can be used as the release\(\) op 143 * of v4l2_file_operations. 144 * 145 * @filp: pointer to struct file 146 * 147 * It deletes and exits the v4l2_fh associated with the file pointer and 148 * frees it. It will do nothing if filp->private_data (the pointer to the 149 * v4l2_fh struct) is %NULL. 150 * 151 * This function always returns 0. 152 */ 153 int v4l2_fh_release(struct file *filp); 154 155 /** 156 * v4l2_fh_is_singular - Returns 1 if this filehandle is the only filehandle 157 * opened for the associated video_device. 158 * 159 * @fh: pointer to &struct v4l2_fh 160 * 161 * If @fh is NULL, then it returns 0. 162 */ 163 int v4l2_fh_is_singular(struct v4l2_fh *fh); 164 165 /** 166 * v4l2_fh_is_singular_file - Returns 1 if this filehandle is the only 167 * filehandle opened for the associated video_device. 168 * 169 * @filp: pointer to struct file 170 * 171 * This is a helper function variant of v4l2_fh_is_singular() with uses 172 * struct file as argument. 173 * 174 * If filp->private_data is %NULL, then it will return 0. 175 */ 176 static inline int v4l2_fh_is_singular_file(struct file *filp) 177 { 178 return v4l2_fh_is_singular(filp->private_data); 179 } 180 181 #endif /* V4L2_EVENT_H */ 182