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@maxwell.research.nokia.com> 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/list.h> 30 31 struct video_device; 32 struct v4l2_events; 33 34 struct v4l2_fh { 35 struct list_head list; 36 struct video_device *vdev; 37 struct v4l2_events *events; /* events, pending and subscribed */ 38 enum v4l2_priority prio; 39 }; 40 41 /* 42 * Initialise the file handle. Parts of the V4L2 framework using the 43 * file handles should be initialised in this function. Must be called 44 * from driver's v4l2_file_operations->open() handler if the driver 45 * uses v4l2_fh. 46 */ 47 int v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev); 48 /* 49 * Add the fh to the list of file handles on a video_device. The file 50 * handle must be initialised first. 51 */ 52 void v4l2_fh_add(struct v4l2_fh *fh); 53 /* 54 * Can be used as the open() op of v4l2_file_operations. 55 * It allocates a v4l2_fh and inits and adds it to the video_device associated 56 * with the file pointer. 57 */ 58 int v4l2_fh_open(struct file *filp); 59 /* 60 * Remove file handle from the list of file handles. Must be called in 61 * v4l2_file_operations->release() handler if the driver uses v4l2_fh. 62 * On error filp->private_data will be NULL, otherwise it will point to 63 * the v4l2_fh struct. 64 */ 65 void v4l2_fh_del(struct v4l2_fh *fh); 66 /* 67 * Release resources related to a file handle. Parts of the V4L2 68 * framework using the v4l2_fh must release their resources here, too. 69 * Must be called in v4l2_file_operations->release() handler if the 70 * driver uses v4l2_fh. 71 */ 72 void v4l2_fh_exit(struct v4l2_fh *fh); 73 /* 74 * Can be used as the release() op of v4l2_file_operations. 75 * It deletes and exits the v4l2_fh associated with the file pointer and 76 * frees it. It will do nothing if filp->private_data (the pointer to the 77 * v4l2_fh struct) is NULL. This function always returns 0. 78 */ 79 int v4l2_fh_release(struct file *filp); 80 /* 81 * Returns 1 if this filehandle is the only filehandle opened for the 82 * associated video_device. If fh is NULL, then it returns 0. 83 */ 84 int v4l2_fh_is_singular(struct v4l2_fh *fh); 85 /* 86 * Helper function with struct file as argument. If filp->private_data is 87 * NULL, then it will return 0. 88 */ 89 static inline int v4l2_fh_is_singular_file(struct file *filp) 90 { 91 return v4l2_fh_is_singular(filp->private_data); 92 } 93 94 #endif /* V4L2_EVENT_H */ 95