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Several drivers need to do something when the first filehandle is opened or the last filehandle is closed. Most implement some use count mechanism, but if they use v4l2_fh, then you can also just check if this is the only filehandle for the device node. A simple helper function can do this. Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
95 lines
3.1 KiB
C
95 lines
3.1 KiB
C
/*
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* v4l2-fh.h
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*
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* V4L2 file handle. Store per file handle data for the V4L2
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* framework. Using file handles is optional for the drivers.
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*
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* Copyright (C) 2009--2010 Nokia Corporation.
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*
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* Contact: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* version 2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
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* 02110-1301 USA
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*/
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#ifndef V4L2_FH_H
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#define V4L2_FH_H
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#include <linux/list.h>
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struct video_device;
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struct v4l2_events;
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struct v4l2_fh {
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struct list_head list;
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struct video_device *vdev;
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struct v4l2_events *events; /* events, pending and subscribed */
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enum v4l2_priority prio;
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};
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/*
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* Initialise the file handle. Parts of the V4L2 framework using the
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* file handles should be initialised in this function. Must be called
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* from driver's v4l2_file_operations->open() handler if the driver
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* uses v4l2_fh.
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*/
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int v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev);
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/*
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* Add the fh to the list of file handles on a video_device. The file
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* handle must be initialised first.
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*/
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void v4l2_fh_add(struct v4l2_fh *fh);
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/*
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* Can be used as the open() op of v4l2_file_operations.
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* It allocates a v4l2_fh and inits and adds it to the video_device associated
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* with the file pointer.
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*/
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int v4l2_fh_open(struct file *filp);
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/*
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* Remove file handle from the list of file handles. Must be called in
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* v4l2_file_operations->release() handler if the driver uses v4l2_fh.
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* On error filp->private_data will be NULL, otherwise it will point to
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* the v4l2_fh struct.
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*/
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void v4l2_fh_del(struct v4l2_fh *fh);
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/*
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* Release resources related to a file handle. Parts of the V4L2
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* framework using the v4l2_fh must release their resources here, too.
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* Must be called in v4l2_file_operations->release() handler if the
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* driver uses v4l2_fh.
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*/
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void v4l2_fh_exit(struct v4l2_fh *fh);
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/*
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* Can be used as the release() op of v4l2_file_operations.
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* It deletes and exits the v4l2_fh associated with the file pointer and
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* frees it. It will do nothing if filp->private_data (the pointer to the
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* v4l2_fh struct) is NULL. This function always returns 0.
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*/
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int v4l2_fh_release(struct file *filp);
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/*
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* Returns 1 if this filehandle is the only filehandle opened for the
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* associated video_device. If fh is NULL, then it returns 0.
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*/
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int v4l2_fh_is_singular(struct v4l2_fh *fh);
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/*
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* Helper function with struct file as argument. If filp->private_data is
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* NULL, then it will return 0.
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*/
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static inline int v4l2_fh_is_singular_file(struct file *filp)
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{
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return v4l2_fh_is_singular(filp->private_data);
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}
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#endif /* V4L2_EVENT_H */
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