forked from Minki/linux
dfddb2441f
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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