[mirror_ubuntu-jammy-kernel.git] / include / media / v4l2-fh.h

/* 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;

#if IS_ENABLED(CONFIG_V4L2_MEM2MEM_DEV)
	struct v4l2_m2m_ctx	*m2m_ctx;
#endif
};

/**
 * 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 */
Commit	Line	Data
1802d0be	1	/* SPDX-License-Identifier: GPL-2.0-only */
1babcb46 SA	2	/*
	3	* v4l2-fh.h
	4	*
	5	* V4L2 file handle. Store per file handle data for the V4L2
	6	* framework. Using file handles is optional for the drivers.
	7	*
	8	* Copyright (C) 2009--2010 Nokia Corporation.
	9	*
8c5dff90	10	* Contact: Sakari Ailus <sakari.ailus@iki.fi>
1babcb46 SA	11	*/
	12
	13	#ifndef V4L2_FH_H
	14	#define V4L2_FH_H
	15
4f1af2a3	16	#include <linux/fs.h>
14351d44	17	#include <linux/kconfig.h>
1babcb46	18	#include <linux/list.h>
c8d185ce	19	#include <linux/videodev2.h>
1babcb46 SA	20
1babcb46 SA	21	struct video_device;
2d28b686	22	struct v4l2_ctrl_handler;
1babcb46	23
4ada120e MCC	24	/**
	25	* struct v4l2_fh - Describes a V4L2 file handler
	26	*
	27	* @list: list of file handlers
	28	* @vdev: pointer to &struct video_device
	29	* @ctrl_handler: pointer to &struct v4l2_ctrl_handler
	30	* @prio: priority of the file handler, as defined by &enum v4l2_priority
	31	*
	32	* @wait: event' s wait queue
ad608fbc SA	33	* @subscribe_lock: serialise changes to the subscribed list; guarantee that
ad608fbc SA	34	* the add and del event callbacks are orderly called
4ada120e MCC	35	* @subscribed: list of subscribed events
	36	* @available: list of events waiting to be dequeued
	37	* @navailable: number of available events at @available list
	38	* @sequence: event sequence number
ad608fbc	39	*
4ada120e MCC	40	* @m2m_ctx: pointer to &struct v4l2_m2m_ctx
4ada120e MCC	41	*/
1babcb46 SA	42	struct v4l2_fh {
	43	struct list_head list;
	44	struct video_device *vdev;
2d28b686	45	struct v4l2_ctrl_handler *ctrl_handler;
fc5602be	46	enum v4l2_priority prio;
523f46d6 HV	47
	48	/* Events */
	49	wait_queue_head_t wait;
ad608fbc	50	struct mutex subscribe_lock;
4ada120e MCC	51	struct list_head subscribed;
4ada120e MCC	52	struct list_head available;
523f46d6	53	unsigned int navailable;
523f46d6	54	u32 sequence;
8e6e8f93 SN	55
	56	#if IS_ENABLED(CONFIG_V4L2_MEM2MEM_DEV)
	57	struct v4l2_m2m_ctx *m2m_ctx;
	58	#endif
1babcb46 SA	59	};
1babcb46 SA	60
4ada120e MCC	61	/**
	62	* v4l2_fh_init - Initialise the file handle.
	63	*
	64	* @fh: pointer to &struct v4l2_fh
	65	* @vdev: pointer to &struct video_device
	66	*
	67	* Parts of the V4L2 framework using the
1babcb46	68	* file handles should be initialised in this function. Must be called
4ada120e MCC	69	* from driver's v4l2_file_operations->open\(\) handler if the driver
4ada120e MCC	70	* uses &struct v4l2_fh.
1babcb46	71	*/
523f46d6	72	void v4l2_fh_init(struct v4l2_fh fh, struct video_device vdev);
4ada120e MCC	73
	74	/**
	75	* v4l2_fh_add - Add the fh to the list of file handles on a video_device.
	76	*
	77	* @fh: pointer to &struct v4l2_fh
	78	*
	79	* .. note::
	80	* The @fh file handle must be initialised first.
1babcb46 SA	81	*/
1babcb46 SA	82	void v4l2_fh_add(struct v4l2_fh *fh);
4ada120e MCC	83
	84	/**
	85	* v4l2_fh_open - Ancillary routine that can be used as the open\(\) op
	86	* of v4l2_file_operations.
	87	*
	88	* @filp: pointer to struct file
	89	*
	90	* It allocates a v4l2_fh and inits and adds it to the &struct video_device
	91	* associated with the file pointer.
73cb4206 HV	92	*/
73cb4206 HV	93	int v4l2_fh_open(struct file *filp);
4ada120e MCC	94
	95	/**
	96	* v4l2_fh_del - Remove file handle from the list of file handles.
	97	*
	98	* @fh: pointer to &struct v4l2_fh
	99	*
	100	* On error filp->private_data will be %NULL, otherwise it will point to
	101	* the &struct v4l2_fh.
	102	*
	103	* .. note::
	104	* Must be called in v4l2_file_operations->release\(\) handler if the driver
	105	* uses &struct v4l2_fh.
1babcb46 SA	106	*/
1babcb46 SA	107	void v4l2_fh_del(struct v4l2_fh *fh);
4ada120e MCC	108
	109	/**
	110	* v4l2_fh_exit - Release resources related to a file handle.
	111	*
	112	* @fh: pointer to &struct v4l2_fh
	113	*
	114	* Parts of the V4L2 framework using the v4l2_fh must release their
	115	* resources here, too.
	116	*
	117	* .. note::
	118	* Must be called in v4l2_file_operations->release\(\) handler if the
	119	* driver uses &struct v4l2_fh.
1babcb46 SA	120	*/
1babcb46 SA	121	void v4l2_fh_exit(struct v4l2_fh *fh);
4ada120e MCC	122
	123	/**
	124	* v4l2_fh_release - Ancillary routine that can be used as the release\(\) op
	125	* of v4l2_file_operations.
	126	*
	127	* @filp: pointer to struct file
	128	*
73cb4206 HV	129	* It deletes and exits the v4l2_fh associated with the file pointer and
73cb4206 HV	130	* frees it. It will do nothing if filp->private_data (the pointer to the
4ada120e MCC	131	* v4l2_fh struct) is %NULL.
	132	*
	133	* This function always returns 0.
73cb4206 HV	134	*/
73cb4206 HV	135	int v4l2_fh_release(struct file *filp);
4ada120e MCC	136
	137	/**
	138	* v4l2_fh_is_singular - Returns 1 if this filehandle is the only filehandle
	139	* opened for the associated video_device.
	140	*
	141	* @fh: pointer to &struct v4l2_fh
	142	*
	143	* If @fh is NULL, then it returns 0.
dfddb244 HV	144	*/
dfddb244 HV	145	int v4l2_fh_is_singular(struct v4l2_fh *fh);
4ada120e MCC	146
	147	/**
	148	* v4l2_fh_is_singular_file - Returns 1 if this filehandle is the only
	149	* filehandle opened for the associated video_device.
	150	*
	151	* @filp: pointer to struct file
	152	*
	153	* This is a helper function variant of v4l2_fh_is_singular() with uses
	154	* struct file as argument.
	155	*
	156	* If filp->private_data is %NULL, then it will return 0.
dfddb244 HV	157	*/
	158	static inline int v4l2_fh_is_singular_file(struct file *filp)
	159	{
	160	return v4l2_fh_is_singular(filp->private_data);
	161	}
1babcb46 SA	162
1babcb46 SA	163	#endif /* V4L2_EVENT_H */