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 50 /* 51 * Initialise the file handle. Parts of the V4L2 framework using the 52 * file handles should be initialised in this function. Must be called 53 * from driver's v4l2_file_operations->open() handler if the driver 54 * uses v4l2_fh. 55 */ 56 void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev); 57 /* 58 * Add the fh to the list of file handles on a video_device. The file 59 * handle must be initialised first. 60 */ 61 void v4l2_fh_add(struct v4l2_fh *fh); 62 /* 63 * Can be used as the open() op of v4l2_file_operations. 64 * It allocates a v4l2_fh and inits and adds it to the video_device associated 65 * with the file pointer. 66 */ 67 int v4l2_fh_open(struct file *filp); 68 /* 69 * Remove file handle from the list of file handles. Must be called in 70 * v4l2_file_operations->release() handler if the driver uses v4l2_fh. 71 * On error filp->private_data will be NULL, otherwise it will point to 72 * the v4l2_fh struct. 73 */ 74 void v4l2_fh_del(struct v4l2_fh *fh); 75 /* 76 * Release resources related to a file handle. Parts of the V4L2 77 * framework using the v4l2_fh must release their resources here, too. 78 * Must be called in v4l2_file_operations->release() handler if the 79 * driver uses v4l2_fh. 80 */ 81 void v4l2_fh_exit(struct v4l2_fh *fh); 82 /* 83 * Can be used as the release() op of v4l2_file_operations. 84 * It deletes and exits the v4l2_fh associated with the file pointer and 85 * frees it. It will do nothing if filp->private_data (the pointer to the 86 * v4l2_fh struct) is NULL. This function always returns 0. 87 */ 88 int v4l2_fh_release(struct file *filp); 89 /* 90 * Returns 1 if this filehandle is the only filehandle opened for the 91 * associated video_device. If fh is NULL, then it returns 0. 92 */ 93 int v4l2_fh_is_singular(struct v4l2_fh *fh); 94 /* 95 * Helper function with struct file as argument. If filp->private_data is 96 * NULL, then it will return 0. 97 */ 98 static inline int v4l2_fh_is_singular_file(struct file *filp) 99 { 100 return v4l2_fh_is_singular(filp->private_data); 101 } 102 103 #endif /* V4L2_EVENT_H */ 104