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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* v4l2-fh.h
*
* V4L2 file handle. Store per file handle data for the V4L2
* framework. Using file handles is optional for the drivers.
*
* Copyright (C) 2009--2010 Nokia Corporation.
*
* Contact: Sakari Ailus <sakari.ailus@iki.fi>
*/
#ifndef V4L2_FH_H
#define V4L2_FH_H
#include <linux/fs.h>
#include <linux/kconfig.h>
#include <linux/list.h>
#include <linux/videodev2.h>
struct video_device;
struct v4l2_ctrl_handler;
/**
* struct v4l2_fh - Describes a V4L2 file handler
*
* @list: list of file handlers
* @vdev: pointer to &struct video_device
* @ctrl_handler: pointer to &struct v4l2_ctrl_handler
* @prio: priority of the file handler, as defined by &enum v4l2_priority
*
* @wait: event' s wait queue
* @subscribe_lock: serialise changes to the subscribed list; guarantee that
* the add and del event callbacks are orderly called
* @subscribed: list of subscribed events
* @available: list of events waiting to be dequeued
* @navailable: number of available events at @available list
* @sequence: event sequence number
*
* @m2m_ctx: pointer to &struct v4l2_m2m_ctx
*/
struct v4l2_fh {
struct list_head list;
struct video_device *vdev;
struct v4l2_ctrl_handler *ctrl_handler;
enum v4l2_priority prio;
/* Events */
wait_queue_head_t wait;
struct mutex subscribe_lock;
struct list_head subscribed;
struct list_head available;
unsigned int navailable;
u32 sequence;
struct v4l2_m2m_ctx *m2m_ctx;
};
/**
* v4l2_fh_init - Initialise the file handle.
*
* @fh: pointer to &struct v4l2_fh
* @vdev: pointer to &struct video_device
*
* Parts of the V4L2 framework using the
* file handles should be initialised in this function. Must be called
* from driver's v4l2_file_operations->open\(\) handler if the driver
* uses &struct v4l2_fh.
*/
void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev);
/**
* v4l2_fh_add - Add the fh to the list of file handles on a video_device.
*
* @fh: pointer to &struct v4l2_fh
*
* .. note::
* The @fh file handle must be initialised first.
*/
void v4l2_fh_add(struct v4l2_fh *fh);
/**
* v4l2_fh_open - Ancillary routine that can be used as the open\(\) op
* of v4l2_file_operations.
*
* @filp: pointer to struct file
*
* It allocates a v4l2_fh and inits and adds it to the &struct video_device
* associated with the file pointer.
*/
int v4l2_fh_open(struct file *filp);
/**
* v4l2_fh_del - Remove file handle from the list of file handles.
*
* @fh: pointer to &struct v4l2_fh
*
* On error filp->private_data will be %NULL, otherwise it will point to
* the &struct v4l2_fh.
*
* .. note::
* Must be called in v4l2_file_operations->release\(\) handler if the driver
* uses &struct v4l2_fh.
*/
void v4l2_fh_del(struct v4l2_fh *fh);
/**
* v4l2_fh_exit - Release resources related to a file handle.
*
* @fh: pointer to &struct v4l2_fh
*
* Parts of the V4L2 framework using the v4l2_fh must release their
* resources here, too.
*
* .. note::
* Must be called in v4l2_file_operations->release\(\) handler if the
* driver uses &struct v4l2_fh.
*/
void v4l2_fh_exit(struct v4l2_fh *fh);
/**
* v4l2_fh_release - Ancillary routine that can be used as the release\(\) op
* of v4l2_file_operations.
*
* @filp: pointer to struct file
*
* It deletes and exits the v4l2_fh associated with the file pointer and
* frees it. It will do nothing if filp->private_data (the pointer to the
* v4l2_fh struct) is %NULL.
*
* This function always returns 0.
*/
int v4l2_fh_release(struct file *filp);
/**
* v4l2_fh_is_singular - Returns 1 if this filehandle is the only filehandle
* opened for the associated video_device.
*
* @fh: pointer to &struct v4l2_fh
*
* If @fh is NULL, then it returns 0.
*/
int v4l2_fh_is_singular(struct v4l2_fh *fh);
/**
* v4l2_fh_is_singular_file - Returns 1 if this filehandle is the only
* filehandle opened for the associated video_device.
*
* @filp: pointer to struct file
*
* This is a helper function variant of v4l2_fh_is_singular() with uses
* struct file as argument.
*
* If filp->private_data is %NULL, then it will return 0.
*/
static inline int v4l2_fh_is_singular_file(struct file *filp)
{
return v4l2_fh_is_singular(filp->private_data);
}
#endif /* V4L2_EVENT_H */
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