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 optional 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 * v4l2_fh_init - Initialise the file handle. 61 * 62 * @fh: pointer to &struct v4l2_fh 63 * @vdev: pointer to &struct video_device 64 * 65 * Parts of the V4L2 framework using the 66 * file handles should be initialised in this function. Must be called 67 * from driver's v4l2_file_operations->open\(\) handler if the driver 68 * uses &struct v4l2_fh. 69 */ 70 void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev); 71 72 /** 73 * v4l2_fh_add - Add the fh to the list of file handles on a video_device. 74 * 75 * @fh: pointer to &struct v4l2_fh 76 * 77 * .. note:: 78 * The @fh file handle must be initialised first. 79 */ 80 void v4l2_fh_add(struct v4l2_fh *fh); 81 82 /** 83 * v4l2_fh_open - Ancillary routine that can be used as the open\(\) op 84 * of v4l2_file_operations. 85 * 86 * @filp: pointer to struct file 87 * 88 * It allocates a v4l2_fh and inits and adds it to the &struct video_device 89 * associated with the file pointer. 90 */ 91 int v4l2_fh_open(struct file *filp); 92 93 /** 94 * v4l2_fh_del - Remove file handle from the list of file handles. 95 * 96 * @fh: pointer to &struct v4l2_fh 97 * 98 * On error filp->private_data will be %NULL, otherwise it will point to 99 * the &struct v4l2_fh. 100 * 101 * .. note:: 102 * Must be called in v4l2_file_operations->release\(\) handler if the driver 103 * uses &struct v4l2_fh. 104 */ 105 void v4l2_fh_del(struct v4l2_fh *fh); 106 107 /** 108 * v4l2_fh_exit - Release resources related to a file handle. 109 * 110 * @fh: pointer to &struct v4l2_fh 111 * 112 * Parts of the V4L2 framework using the v4l2_fh must release their 113 * resources here, too. 114 * 115 * .. note:: 116 * Must be called in v4l2_file_operations->release\(\) handler if the 117 * driver uses &struct v4l2_fh. 118 */ 119 void v4l2_fh_exit(struct v4l2_fh *fh); 120 121 /** 122 * v4l2_fh_release - Ancillary routine that can be used as the release\(\) op 123 * of v4l2_file_operations. 124 * 125 * @filp: pointer to struct file 126 * 127 * It deletes and exits the v4l2_fh associated with the file pointer and 128 * frees it. It will do nothing if filp->private_data (the pointer to the 129 * v4l2_fh struct) is %NULL. 130 * 131 * This function always returns 0. 132 */ 133 int v4l2_fh_release(struct file *filp); 134 135 /** 136 * v4l2_fh_is_singular - Returns 1 if this filehandle is the only filehandle 137 * opened for the associated video_device. 138 * 139 * @fh: pointer to &struct v4l2_fh 140 * 141 * If @fh is NULL, then it returns 0. 142 */ 143 int v4l2_fh_is_singular(struct v4l2_fh *fh); 144 145 /** 146 * v4l2_fh_is_singular_file - Returns 1 if this filehandle is the only 147 * filehandle opened for the associated video_device. 148 * 149 * @filp: pointer to struct file 150 * 151 * This is a helper function variant of v4l2_fh_is_singular() with uses 152 * struct file as argument. 153 * 154 * If filp->private_data is %NULL, then it will return 0. 155 */ 156 static inline int v4l2_fh_is_singular_file(struct file *filp) 157 { 158 return v4l2_fh_is_singular(filp->private_data); 159 } 160 161 #endif /* V4L2_EVENT_H */ 162