[linux-2.6-block.git] / include / media / v4l2-event.h

/*
 * v4l2-event.h
 *
 * V4L2 events.
 *
 * Copyright (C) 2009--2010 Nokia Corporation.
 *
 * Contact: Sakari Ailus <sakari.ailus@iki.fi>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 */

#ifndef V4L2_EVENT_H
#define V4L2_EVENT_H

#include <linux/types.h>
#include <linux/videodev2.h>
#include <linux/wait.h>

/*
 * Overview:
 *
 * Events are subscribed per-filehandle. An event specification consists of a
 * type and is optionally associated with an object identified through the
 * 'id' field. So an event is uniquely identified by the (type, id) tuple.
 *
 * The v4l2-fh struct has a list of subscribed events. The v4l2_subscribed_event
 * struct is added to that list, one for every subscribed event.
 *
 * Each v4l2_subscribed_event struct ends with an array of v4l2_kevent structs.
 * This array (ringbuffer, really) is used to store any events raised by the
 * driver. The v4l2_kevent struct links into the 'available' list of the
 * v4l2_fh struct so VIDIOC_DQEVENT will know which event to dequeue first.
 *
 * Finally, if the event subscription is associated with a particular object
 * such as a V4L2 control, then that object needs to know about that as well
 * so that an event can be raised by that object. So the 'node' field can
 * be used to link the v4l2_subscribed_event struct into a list of that
 * object.
 *
 * So to summarize:
 *
 * struct v4l2_fh has two lists: one of the subscribed events, and one of the
 * pending events.
 *
 * struct v4l2_subscribed_event has a ringbuffer of raised (pending) events of
 * that particular type.
 *
 * If struct v4l2_subscribed_event is associated with a specific object, then
 * that object will have an internal list of struct v4l2_subscribed_event so
 * it knows who subscribed an event to that object.
 */

struct v4l2_fh;
struct v4l2_subdev;
struct v4l2_subscribed_event;
struct video_device;

/**
 * struct v4l2_kevent - Internal kernel event struct.
 * @list:	List node for the v4l2_fh->available list.
 * @sev:	Pointer to parent v4l2_subscribed_event.
 * @event:	The event itself.
  */
struct v4l2_kevent {
	struct list_head	list;
	struct v4l2_subscribed_event *sev;
	struct v4l2_event	event;
};

/** struct v4l2_subscribed_event_ops - Subscribed event operations.
 *
 * @add:	Optional callback, called when a new listener is added
 * @del:	Optional callback, called when a listener stops listening
 * @replace:	Optional callback that can replace event 'old' with event 'new'.
 * @merge:	Optional callback that can merge event 'old' into event 'new'.
 */
struct v4l2_subscribed_event_ops {
	int  (*add)(struct v4l2_subscribed_event *sev, unsigned elems);
	void (*del)(struct v4l2_subscribed_event *sev);
	void (*replace)(struct v4l2_event *old, const struct v4l2_event *new);
	void (*merge)(const struct v4l2_event *old, struct v4l2_event *new);
};

/**
 * struct v4l2_subscribed_event - Internal struct representing a subscribed event.
 * @list:	List node for the v4l2_fh->subscribed list.
 * @type:	Event type.
 * @id:	Associated object ID (e.g. control ID). 0 if there isn't any.
 * @flags:	Copy of v4l2_event_subscription->flags.
 * @fh:	Filehandle that subscribed to this event.
 * @node:	List node that hooks into the object's event list (if there is one).
 * @ops:	v4l2_subscribed_event_ops
 * @elems:	The number of elements in the events array.
 * @first:	The index of the events containing the oldest available event.
 * @in_use:	The number of queued events.
 * @events:	An array of @elems events.
 */
struct v4l2_subscribed_event {
	struct list_head	list;
	u32			type;
	u32			id;
	u32			flags;
	struct v4l2_fh		*fh;
	struct list_head	node;
	const struct v4l2_subscribed_event_ops *ops;
	unsigned		elems;
	unsigned		first;
	unsigned		in_use;
	struct v4l2_kevent	events[];
};

int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
		       int nonblocking);
void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev);
void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev);
int v4l2_event_pending(struct v4l2_fh *fh);
int v4l2_event_subscribe(struct v4l2_fh *fh,
			 const struct v4l2_event_subscription *sub, unsigned elems,
			 const struct v4l2_subscribed_event_ops *ops);
int v4l2_event_unsubscribe(struct v4l2_fh *fh,
			   const struct v4l2_event_subscription *sub);
void v4l2_event_unsubscribe_all(struct v4l2_fh *fh);
int v4l2_event_subdev_unsubscribe(struct v4l2_subdev *sd, struct v4l2_fh *fh,
				  struct v4l2_event_subscription *sub);
int v4l2_src_change_event_subscribe(struct v4l2_fh *fh,
				const struct v4l2_event_subscription *sub);
int v4l2_src_change_event_subdev_subscribe(struct v4l2_subdev *sd,
		struct v4l2_fh *fh, struct v4l2_event_subscription *sub);
#endif /* V4L2_EVENT_H */
Commit	Line	Data
c3b5b024 SA	1	/*
	2	* v4l2-event.h
	3	*
	4	* V4L2 events.
	5	*
	6	* Copyright (C) 2009--2010 Nokia Corporation.
	7	*
8c5dff90	8	* Contact: Sakari Ailus <sakari.ailus@iki.fi>
c3b5b024 SA	9	*
	10	* This program is free software; you can redistribute it and/or
	11	* modify it under the terms of the GNU General Public License
	12	* version 2 as published by the Free Software Foundation.
	13	*
	14	* This program is distributed in the hope that it will be useful, but
	15	* WITHOUT ANY WARRANTY; without even the implied warranty of
	16	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	17	* General Public License for more details.
	18	*
	19	* You should have received a copy of the GNU General Public License
	20	* along with this program; if not, write to the Free Software
	21	* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
	22	* 02110-1301 USA
	23	*/
	24
	25	#ifndef V4L2_EVENT_H
	26	#define V4L2_EVENT_H
	27
	28	#include <linux/types.h>
	29	#include <linux/videodev2.h>
	30	#include <linux/wait.h>
	31
3ad57c33 HV	32	/*
	33	* Overview:
	34	*
	35	* Events are subscribed per-filehandle. An event specification consists of a
	36	* type and is optionally associated with an object identified through the
	37	* 'id' field. So an event is uniquely identified by the (type, id) tuple.
	38	*
	39	* The v4l2-fh struct has a list of subscribed events. The v4l2_subscribed_event
	40	* struct is added to that list, one for every subscribed event.
	41	*
	42	* Each v4l2_subscribed_event struct ends with an array of v4l2_kevent structs.
	43	* This array (ringbuffer, really) is used to store any events raised by the
	44	* driver. The v4l2_kevent struct links into the 'available' list of the
	45	* v4l2_fh struct so VIDIOC_DQEVENT will know which event to dequeue first.
	46	*
	47	* Finally, if the event subscription is associated with a particular object
	48	* such as a V4L2 control, then that object needs to know about that as well
	49	* so that an event can be raised by that object. So the 'node' field can
	50	* be used to link the v4l2_subscribed_event struct into a list of that
	51	* object.
	52	*
	53	* So to summarize:
	54	*
	55	* struct v4l2_fh has two lists: one of the subscribed events, and one of the
	56	* pending events.
	57	*
	58	* struct v4l2_subscribed_event has a ringbuffer of raised (pending) events of
	59	* that particular type.
	60	*
	61	* If struct v4l2_subscribed_event is associated with a specific object, then
	62	* that object will have an internal list of struct v4l2_subscribed_event so
	63	* it knows who subscribed an event to that object.
	64	*/
	65
c3b5b024	66	struct v4l2_fh;
4f4d14b7	67	struct v4l2_subdev;
f1e393de	68	struct v4l2_subscribed_event;
c3b5b024 SA	69	struct video_device;
c3b5b024 SA	70
b6fce850 MCC	71	/**
	72	* struct v4l2_kevent - Internal kernel event struct.
	73	* @list: List node for the v4l2_fh->available list.
	74	* @sev: Pointer to parent v4l2_subscribed_event.
	75	* @event: The event itself.
3f66f0ed	76	*/
c3b5b024 SA	77	struct v4l2_kevent {
c3b5b024 SA	78	struct list_head list;
f1e393de	79	struct v4l2_subscribed_event *sev;
c3b5b024 SA	80	struct v4l2_event event;
	81	};
	82
c53c2549	83	/** struct v4l2_subscribed_event_ops - Subscribed event operations.
b6fce850 MCC	84	*
	85	* @add: Optional callback, called when a new listener is added
	86	* @del: Optional callback, called when a listener stops listening
	87	* @replace: Optional callback that can replace event 'old' with event 'new'.
	88	* @merge: Optional callback that can merge event 'old' into event 'new'.
	89	*/
c53c2549	90	struct v4l2_subscribed_event_ops {
6e6d76cd	91	int (add)(struct v4l2_subscribed_event sev, unsigned elems);
c53c2549 HG	92	void (del)(struct v4l2_subscribed_event sev);
	93	void (replace)(struct v4l2_event old, const struct v4l2_event *new);
	94	void (merge)(const struct v4l2_event old, struct v4l2_event *new);
	95	};
	96
b6fce850 MCC	97	/**
	98	* struct v4l2_subscribed_event - Internal struct representing a subscribed event.
	99	* @list: List node for the v4l2_fh->subscribed list.
	100	* @type: Event type.
	101	* @id: Associated object ID (e.g. control ID). 0 if there isn't any.
	102	* @flags: Copy of v4l2_event_subscription->flags.
	103	* @fh: Filehandle that subscribed to this event.
	104	* @node: List node that hooks into the object's event list (if there is one).
	105	* @ops: v4l2_subscribed_event_ops
	106	* @elems: The number of elements in the events array.
	107	* @first: The index of the events containing the oldest available event.
	108	* @in_use: The number of queued events.
	109	* @events: An array of @elems events.
	110	*/
c3b5b024 SA	111	struct v4l2_subscribed_event {
	112	struct list_head list;
	113	u32 type;
6e239399	114	u32 id;
77068d36	115	u32 flags;
77068d36	116	struct v4l2_fh *fh;
77068d36	117	struct list_head node;
c53c2549	118	const struct v4l2_subscribed_event_ops *ops;
f1e393de	119	unsigned elems;
f1e393de	120	unsigned first;
f1e393de	121	unsigned in_use;
f1e393de	122	struct v4l2_kevent events[];
c3b5b024 SA	123	};
c3b5b024 SA	124
c3b5b024 SA	125	int v4l2_event_dequeue(struct v4l2_fh fh, struct v4l2_event event,
	126	int nonblocking);
	127	void v4l2_event_queue(struct video_device vdev, const struct v4l2_event ev);
6e239399	128	void v4l2_event_queue_fh(struct v4l2_fh fh, const struct v4l2_event ev);
c3b5b024 SA	129	int v4l2_event_pending(struct v4l2_fh *fh);
c3b5b024 SA	130	int v4l2_event_subscribe(struct v4l2_fh *fh,
85f5fe39	131	const struct v4l2_event_subscription *sub, unsigned elems,
c53c2549	132	const struct v4l2_subscribed_event_ops *ops);
c3b5b024	133	int v4l2_event_unsubscribe(struct v4l2_fh *fh,
85f5fe39	134	const struct v4l2_event_subscription *sub);
f1e393de	135	void v4l2_event_unsubscribe_all(struct v4l2_fh *fh);
4f4d14b7 SN	136	int v4l2_event_subdev_unsubscribe(struct v4l2_subdev sd, struct v4l2_fh fh,
4f4d14b7 SN	137	struct v4l2_event_subscription *sub);
3cbe6e5b AK	138	int v4l2_src_change_event_subscribe(struct v4l2_fh *fh,
	139	const struct v4l2_event_subscription *sub);
	140	int v4l2_src_change_event_subdev_subscribe(struct v4l2_subdev *sd,
	141	struct v4l2_fh fh, struct v4l2_event_subscription sub);
c3b5b024	142	#endif /* V4L2_EVENT_H */