[PATCH v8 0/6] V4L2 file handles and event interface

[PATCH v8 0/6] V4L2 file handles and event interface

[Sakari Ailus]

Hi,

Here's the tenth version of the V4L2 file handle and event interface
patchset.

The patchset has been tested with the OMAP 3 ISP driver. Patches for
OMAP 3 ISP are not part of this patchset but are available in Gitorious
(branch is called event):

	git://gitorious.org/omap3camera/mainline.git event

The patchset I'm posting now is against the v4l-dvb tree instead of
linux-omap. The omap3camera tree thus has a slightly different
version of these patches (just Makefiles) due to different baselines.

Some more comments from Hans and Randy. There are only improvements in
documentation this time.

Comments are welcome as always.

Cheers,

-- 
Sakari Ailus
sakari.ailus@maxwell.research.nokia.com

[PATCH v8 1/6] V4L: File handles

[Sakari Ailus]

This patch adds a list of v4l2_fh structures to every video_device.
It allows using file handle related information in V4L2. The event interface
is one example of such use.

Video device drivers should use the v4l2_fh pointer as their
file->private_data.

Signed-off-by: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
---
 drivers/media/video/Makefile   |    2 +-
 drivers/media/video/v4l2-dev.c |    4 ++
 drivers/media/video/v4l2-fh.c  |   66 ++++++++++++++++++++++++++++++++++++++++
 include/media/v4l2-dev.h       |    5 +++
 include/media/v4l2-fh.h        |   42 +++++++++++++++++++++++++
 5 files changed, 118 insertions(+), 1 deletions(-)
 create mode 100644 drivers/media/video/v4l2-fh.c
 create mode 100644 include/media/v4l2-fh.h

diff --git a/drivers/media/video/Makefile b/drivers/media/video/Makefile
index 5163289..14bf69a 100644
--- a/drivers/media/video/Makefile
+++ b/drivers/media/video/Makefile
@@ -10,7 +10,7 @@ stkwebcam-objs	:=	stk-webcam.o stk-sensor.o
 
 omap2cam-objs	:=	omap24xxcam.o omap24xxcam-dma.o
 
-videodev-objs	:=	v4l2-dev.o v4l2-ioctl.o v4l2-device.o
+videodev-objs	:=	v4l2-dev.o v4l2-ioctl.o v4l2-device.o v4l2-fh.o
 
 # V4L2 core modules
 
diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c
index 7090699..65a7b30 100644
--- a/drivers/media/video/v4l2-dev.c
+++ b/drivers/media/video/v4l2-dev.c
@@ -421,6 +421,10 @@ static int __video_register_device(struct video_device *vdev, int type, int nr,
 	if (!vdev->release)
 		return -EINVAL;
 
+	/* v4l2_fh support */
+	spin_lock_init(&vdev->fh_lock);
+	INIT_LIST_HEAD(&vdev->fh_list);
+
 	/* Part 1: check device type */
 	switch (type) {
 	case VFL_TYPE_GRABBER:
diff --git a/drivers/media/video/v4l2-fh.c b/drivers/media/video/v4l2-fh.c
new file mode 100644
index 0000000..93ea0af
--- /dev/null
+++ b/drivers/media/video/v4l2-fh.c
@@ -0,0 +1,66 @@
+/*
+ * v4l2-fh.c
+ *
+ * V4L2 file handles.
+ *
+ * Copyright (C) 2009--2010 Nokia Corporation.
+ *
+ * Contact: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
+ *
+ * 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
+ */
+
+#include <linux/bitops.h>
+#include <media/v4l2-dev.h>
+#include <media/v4l2-fh.h>
+
+int v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev)
+{
+	fh->vdev = vdev;
+	INIT_LIST_HEAD(&fh->list);
+	set_bit(V4L2_FL_USES_V4L2_FH, &fh->vdev->flags);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(v4l2_fh_init);
+
+void v4l2_fh_add(struct v4l2_fh *fh)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
+	list_add(&fh->list, &fh->vdev->fh_list);
+	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
+}
+EXPORT_SYMBOL_GPL(v4l2_fh_add);
+
+void v4l2_fh_del(struct v4l2_fh *fh)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
+	list_del_init(&fh->list);
+	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
+}
+EXPORT_SYMBOL_GPL(v4l2_fh_del);
+
+void v4l2_fh_exit(struct v4l2_fh *fh)
+{
+	if (fh->vdev == NULL)
+		return;
+
+	fh->vdev = NULL;
+}
+EXPORT_SYMBOL_GPL(v4l2_fh_exit);
diff --git a/include/media/v4l2-dev.h b/include/media/v4l2-dev.h
index 2dee938..bebe44b 100644
--- a/include/media/v4l2-dev.h
+++ b/include/media/v4l2-dev.h
@@ -32,6 +32,7 @@ struct v4l2_device;
    Drivers can clear this flag if they want to block all future
    device access. It is cleared by video_unregister_device. */
 #define V4L2_FL_REGISTERED	(0)
+#define V4L2_FL_USES_V4L2_FH	(1)
 
 struct v4l2_file_operations {
 	struct module *owner;
@@ -77,6 +78,10 @@ struct video_device
 	/* attribute to differentiate multiple indices on one physical device */
 	int index;
 
+	/* V4L2 file handles */
+	spinlock_t		fh_lock; /* Lock for all v4l2_fhs */
+	struct list_head	fh_list; /* List of struct v4l2_fh */
+
 	int debug;			/* Activates debug level*/
 
 	/* Video standard vars */
diff --git a/include/media/v4l2-fh.h b/include/media/v4l2-fh.h
new file mode 100644
index 0000000..410e86c
--- /dev/null
+++ b/include/media/v4l2-fh.h
@@ -0,0 +1,42 @@
+/*
+ * v4l2-fh.h
+ *
+ * V4L2 file handle.
+ *
+ * Copyright (C) 2009--2010 Nokia Corporation.
+ *
+ * Contact: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
+ *
+ * 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_FH_H
+#define V4L2_FH_H
+
+#include <linux/list.h>
+
+struct video_device;
+
+struct v4l2_fh {
+	struct list_head	list;
+	struct video_device	*vdev;
+};
+
+int v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev);
+void v4l2_fh_add(struct v4l2_fh *fh);
+void v4l2_fh_del(struct v4l2_fh *fh);
+void v4l2_fh_exit(struct v4l2_fh *fh);
+
+#endif /* V4L2_EVENT_H */
-- 
1.5.6.5

[PATCH v8 2/6] V4L: File handles: Add documentation

[Sakari Ailus]

Add documentation on using V4L2 file handles (v4l2_fh) in V4L2 drivers.

Signed-off-by: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
---
 Documentation/video4linux/v4l2-framework.txt |   37 ++++++++++++++++++++++++++
 1 files changed, 37 insertions(+), 0 deletions(-)

diff --git a/Documentation/video4linux/v4l2-framework.txt b/Documentation/video4linux/v4l2-framework.txt
index 74d677c..bfaf0c5 100644
--- a/Documentation/video4linux/v4l2-framework.txt
+++ b/Documentation/video4linux/v4l2-framework.txt
@@ -695,3 +695,40 @@ The better way to understand it is to take a look at vivi driver. One
 of the main reasons for vivi is to be a videobuf usage example. the
 vivi_thread_tick() does the task that the IRQ callback would do on PCI
 drivers (or the irq callback on USB).
+
+struct v4l2_fh
+--------------
+
+struct v4l2_fh provides a way to easily keep file handle specific data
+that is used by the V4L2 framework.
+
+struct v4l2_fh is allocated as a part of the driver's own file handle
+structure and is set to file->private_data in the driver's open
+function by the driver. Drivers can extract their own file handle
+structure by using the container_of macro.
+
+Useful functions:
+
+- v4l2_fh_init()
+
+  Initialise the file handle. This *MUST* be performed in the driver's
+  v4l2_file_operations->open() handler.
+
+- v4l2_fh_add()
+
+  Add a v4l2_fh to video_device file handle list. May be called after
+  initialising the file handle.
+
+- v4l2_fh_del()
+
+  Unassociate the file handle from video_device(). The file handle
+  exit function may now be called.
+
+- v4l2_fh_exit()
+
+  Uninitialise the file handle. After uninitialisation the v4l2_fh
+  memory can be freed.
+
+The users of v4l2_fh know whether a driver uses v4l2_fh as its
+file->private_data pointer by testing the V4L2_FL_USES_V4L2_FH bit in
+video_device->flags.
-- 
1.5.6.5

[PATCH v8 3/6] V4L: Events: Add new ioctls for events

[Sakari Ailus]

This patch adds a set of new ioctls to the V4L2 API. The ioctls conform to
V4L2 Events RFC version 2.3:

<URL:http://www.spinics.net/lists/linux-media/msg12033.html>

Signed-off-by: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
---
 drivers/media/video/v4l2-compat-ioctl32.c |    3 +++
 drivers/media/video/v4l2-ioctl.c          |    3 +++
 include/linux/videodev2.h                 |   26 ++++++++++++++++++++++++++
 3 files changed, 32 insertions(+), 0 deletions(-)

diff --git a/drivers/media/video/v4l2-compat-ioctl32.c b/drivers/media/video/v4l2-compat-ioctl32.c
index f77f84b..9004a5f 100644
--- a/drivers/media/video/v4l2-compat-ioctl32.c
+++ b/drivers/media/video/v4l2-compat-ioctl32.c
@@ -1086,6 +1086,9 @@ long v4l2_compat_ioctl32(struct file *file, unsigned int cmd, unsigned long arg)
 	case VIDIOC_QUERY_DV_PRESET:
 	case VIDIOC_S_DV_TIMINGS:
 	case VIDIOC_G_DV_TIMINGS:
+	case VIDIOC_DQEVENT:
+	case VIDIOC_SUBSCRIBE_EVENT:
+	case VIDIOC_UNSUBSCRIBE_EVENT:
 		ret = do_video_ioctl(file, cmd, arg);
 		break;
 
diff --git a/drivers/media/video/v4l2-ioctl.c b/drivers/media/video/v4l2-ioctl.c
index 4b11257..34c7d6e 100644
--- a/drivers/media/video/v4l2-ioctl.c
+++ b/drivers/media/video/v4l2-ioctl.c
@@ -290,6 +290,9 @@ static const char *v4l2_ioctls[] = {
 	[_IOC_NR(VIDIOC_QUERY_DV_PRESET)]  = "VIDIOC_QUERY_DV_PRESET",
 	[_IOC_NR(VIDIOC_S_DV_TIMINGS)]     = "VIDIOC_S_DV_TIMINGS",
 	[_IOC_NR(VIDIOC_G_DV_TIMINGS)]     = "VIDIOC_G_DV_TIMINGS",
+	[_IOC_NR(VIDIOC_DQEVENT)]	   = "VIDIOC_DQEVENT",
+	[_IOC_NR(VIDIOC_SUBSCRIBE_EVENT)]  = "VIDIOC_SUBSCRIBE_EVENT",
+	[_IOC_NR(VIDIOC_UNSUBSCRIBE_EVENT)] = "VIDIOC_UNSUBSCRIBE_EVENT",
 };
 #define V4L2_IOCTLS ARRAY_SIZE(v4l2_ioctls)
 
diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
index 3c26560..d3b1446 100644
--- a/include/linux/videodev2.h
+++ b/include/linux/videodev2.h
@@ -1622,6 +1622,29 @@ struct v4l2_streamparm {
 };
 
 /*
+ *	E V E N T S
+ */
+
+struct v4l2_event {
+	__u32				type;
+	union {
+		__u8			data[64];
+	} u;
+	__u32				pending;
+	__u32				sequence;
+	struct timespec			timestamp;
+	__u32				reserved[9];
+};
+
+struct v4l2_event_subscription {
+	__u32				type;
+	__u32				reserved[7];
+};
+
+#define V4L2_EVENT_ALL				0
+#define V4L2_EVENT_PRIVATE_START		0x08000000
+
+/*
  *	A D V A N C E D   D E B U G G I N G
  *
  *	NOTE: EXPERIMENTAL API, NEVER RELY ON THIS IN APPLICATIONS!
@@ -1743,6 +1766,9 @@ struct v4l2_dbg_chip_ident {
 #define	VIDIOC_QUERY_DV_PRESET	_IOR('V',  86, struct v4l2_dv_preset)
 #define	VIDIOC_S_DV_TIMINGS	_IOWR('V', 87, struct v4l2_dv_timings)
 #define	VIDIOC_G_DV_TIMINGS	_IOWR('V', 88, struct v4l2_dv_timings)
+#define	VIDIOC_DQEVENT		 _IOR('V', 89, struct v4l2_event)
+#define	VIDIOC_SUBSCRIBE_EVENT	 _IOW('V', 90, struct v4l2_event_subscription)
+#define	VIDIOC_UNSUBSCRIBE_EVENT _IOW('V', 91, struct v4l2_event_subscription)
 
 /* Reminder: when adding new ioctls please add support for them to
    drivers/media/video/v4l2-compat-ioctl32.c as well! */
-- 
1.5.6.5

[PATCH v8 4/6] V4L: Events: Add backend

[Sakari Ailus]

Add event handling backend to V4L2. The backend handles event subscription
and delivery to file handles. Event subscriptions are based on file handle.
Events may be delivered to all subscribed file handles on a device
independent of where they originate from.

Signed-off-by: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
---
 drivers/media/video/Makefile     |    3 +-
 drivers/media/video/v4l2-event.c |  289 ++++++++++++++++++++++++++++++++++++++
 drivers/media/video/v4l2-fh.c    |    6 +-
 include/media/v4l2-event.h       |   67 +++++++++
 include/media/v4l2-fh.h          |    2 +
 5 files changed, 365 insertions(+), 2 deletions(-)
 create mode 100644 drivers/media/video/v4l2-event.c
 create mode 100644 include/media/v4l2-event.h

diff --git a/drivers/media/video/Makefile b/drivers/media/video/Makefile
index 14bf69a..b84abfe 100644
--- a/drivers/media/video/Makefile
+++ b/drivers/media/video/Makefile
@@ -10,7 +10,8 @@ stkwebcam-objs	:=	stk-webcam.o stk-sensor.o
 
 omap2cam-objs	:=	omap24xxcam.o omap24xxcam-dma.o
 
-videodev-objs	:=	v4l2-dev.o v4l2-ioctl.o v4l2-device.o v4l2-fh.o
+videodev-objs	:=	v4l2-dev.o v4l2-ioctl.o v4l2-device.o v4l2-fh.o \
+			v4l2-event.o
 
 # V4L2 core modules
 
diff --git a/drivers/media/video/v4l2-event.c b/drivers/media/video/v4l2-event.c
new file mode 100644
index 0000000..aea4332
--- /dev/null
+++ b/drivers/media/video/v4l2-event.c
@@ -0,0 +1,289 @@
+/*
+ * v4l2-event.c
+ *
+ * V4L2 events.
+ *
+ * Copyright (C) 2009--2010 Nokia Corporation.
+ *
+ * Contact: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
+ *
+ * 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
+ */
+
+#include <media/v4l2-dev.h>
+#include <media/v4l2-fh.h>
+#include <media/v4l2-event.h>
+
+#include <linux/sched.h>
+
+int v4l2_event_init(struct v4l2_fh *fh)
+{
+	fh->events = kzalloc(sizeof(*fh->events), GFP_KERNEL);
+	if (fh->events == NULL)
+		return -ENOMEM;
+
+	init_waitqueue_head(&fh->events->wait);
+
+	INIT_LIST_HEAD(&fh->events->free);
+	INIT_LIST_HEAD(&fh->events->available);
+	INIT_LIST_HEAD(&fh->events->subscribed);
+
+	fh->events->sequence = -1;
+
+	return 0;
+}
+
+int v4l2_event_alloc(struct v4l2_fh *fh, unsigned int n)
+{
+	struct v4l2_events *events = fh->events;
+	unsigned long flags;
+
+	if (!events) {
+		WARN_ON(1);
+		return -ENOMEM;
+	}
+
+	while (events->nallocated < n) {
+		struct v4l2_kevent *kev;
+
+		kev = kzalloc(sizeof(*kev), GFP_KERNEL);
+		if (kev == NULL)
+			return -ENOMEM;
+
+		spin_lock_irqsave(&fh->vdev->fh_lock, flags);
+		list_add_tail(&kev->list, &events->free);
+		events->nallocated++;
+		spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(v4l2_event_alloc);
+
+#define list_kfree(list, type, member)				\
+	while (!list_empty(list)) {				\
+		type *hi;					\
+		hi = list_first_entry(list, type, member);	\
+		list_del(&hi->member);				\
+		kfree(hi);					\
+	}
+
+void v4l2_event_free(struct v4l2_fh *fh)
+{
+	struct v4l2_events *events = fh->events;
+
+	if (!events)
+		return;
+
+	list_kfree(&events->free, struct v4l2_kevent, list);
+	list_kfree(&events->available, struct v4l2_kevent, list);
+	list_kfree(&events->subscribed, struct v4l2_subscribed_event, list);
+
+	kfree(events);
+	fh->events = NULL;
+}
+EXPORT_SYMBOL_GPL(v4l2_event_free);
+
+static int __v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event)
+{
+	struct v4l2_events *events = fh->events;
+	struct v4l2_kevent *kev;
+	unsigned long flags;
+
+	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
+
+	if (list_empty(&events->available)) {
+		spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
+		return -ENOENT;
+	}
+
+	WARN_ON(events->navailable == 0);
+
+	kev = list_first_entry(&events->available, struct v4l2_kevent, list);
+	list_move(&kev->list, &events->free);
+	events->navailable--;
+
+	kev->event.pending = events->navailable;
+	*event = kev->event;
+
+	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
+
+	return 0;
+}
+
+int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
+                      int nonblocking)
+{
+       struct v4l2_events *events = fh->events;
+       int ret;
+
+       if (nonblocking)
+               return __v4l2_event_dequeue(fh, event);
+
+       do {
+               ret = wait_event_interruptible(events->wait,
+                                              events->navailable != 0);
+               if (ret < 0)
+                       return ret;
+
+               ret = __v4l2_event_dequeue(fh, event);
+       } while (ret == -ENOENT);
+
+       return ret;
+}
+
+/* Caller must hold fh->event->lock! */
+static struct v4l2_subscribed_event *v4l2_event_subscribed(
+	struct v4l2_fh *fh, u32 type)
+{
+	struct v4l2_events *events = fh->events;
+	struct v4l2_subscribed_event *sev;
+
+	WARN_ON(!spin_is_locked(&fh->vdev->fh_lock));
+
+	list_for_each_entry(sev, &events->subscribed, list) {
+		if (sev->type == type)
+			return sev;
+	}
+
+	return NULL;
+}
+
+void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev)
+{
+	struct v4l2_fh *fh;
+	unsigned long flags;
+	struct timespec timestamp;
+
+	ktime_get_ts(&timestamp);
+
+	spin_lock_irqsave(&vdev->fh_lock, flags);
+
+	list_for_each_entry(fh, &vdev->fh_list, list) {
+		struct v4l2_events *events = fh->events;
+		struct v4l2_kevent *kev;
+
+		/* Are we subscribed? */
+		if (!v4l2_event_subscribed(fh, ev->type))
+			continue;
+
+		/* Increase event sequence number on fh. */
+		events->sequence++;
+
+		/* Do we have any free events? */
+		if (list_empty(&events->free))
+			continue;
+
+		/* Take one and fill it. */
+		kev = list_first_entry(&events->free, struct v4l2_kevent, list);
+		kev->event.type = ev->type;
+		kev->event.u = ev->u;
+		kev->event.timestamp = timestamp;
+		kev->event.sequence = events->sequence;
+		list_move_tail(&kev->list, &events->available);
+
+		events->navailable++;
+
+		wake_up_all(&events->wait);
+	}
+
+	spin_unlock_irqrestore(&vdev->fh_lock, flags);
+}
+EXPORT_SYMBOL_GPL(v4l2_event_queue);
+
+int v4l2_event_pending(struct v4l2_fh *fh)
+{
+	return fh->events->navailable;
+}
+EXPORT_SYMBOL_GPL(v4l2_event_pending);
+
+int v4l2_event_subscribe(struct v4l2_fh *fh,
+			 struct v4l2_event_subscription *sub)
+{
+	struct v4l2_events *events = fh->events;
+	struct v4l2_subscribed_event *sev;
+	unsigned long flags;
+
+	if (fh->events == NULL) {
+		WARN_ON(1);
+		return -ENOMEM;
+	}
+
+	sev = kmalloc(sizeof(*sev), GFP_KERNEL);
+	if (!sev)
+		return -ENOMEM;
+
+	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
+
+	if (v4l2_event_subscribed(fh, sub->type) == NULL) {
+		INIT_LIST_HEAD(&sev->list);
+		sev->type = sub->type;
+
+		list_add(&sev->list, &events->subscribed);
+		sev = NULL;
+	}
+
+	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
+
+	kfree(sev);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
+
+static void v4l2_event_unsubscribe_all(struct v4l2_fh *fh)
+{
+	struct v4l2_events *events = fh->events;
+	struct v4l2_subscribed_event *sev;
+	unsigned long flags;
+
+	do {
+		sev = NULL;
+
+		spin_lock_irqsave(&fh->vdev->fh_lock, flags);
+		if (!list_empty(&events->subscribed)) {
+			sev = list_first_entry(&events->subscribed,
+				       struct v4l2_subscribed_event, list);
+			list_del(&sev->list);
+		}
+		spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
+		kfree(sev);
+	} while (sev);
+}
+
+int v4l2_event_unsubscribe(struct v4l2_fh *fh,
+			   struct v4l2_event_subscription *sub)
+{
+	struct v4l2_subscribed_event *sev;
+	unsigned long flags;
+
+	if (sub->type == V4L2_EVENT_ALL) {
+		v4l2_event_unsubscribe_all(fh);
+		return 0;
+	}
+
+	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
+
+	sev = v4l2_event_subscribed(fh, sub->type);
+	if (sev != NULL)
+		list_del(&sev->list);
+
+	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
+
+	kfree(sev);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe);
diff --git a/drivers/media/video/v4l2-fh.c b/drivers/media/video/v4l2-fh.c
index 93ea0af..aab2fb6 100644
--- a/drivers/media/video/v4l2-fh.c
+++ b/drivers/media/video/v4l2-fh.c
@@ -25,6 +25,8 @@
 #include <linux/bitops.h>
 #include <media/v4l2-dev.h>
 #include <media/v4l2-fh.h>
+#include <media/v4l2-event.h>
+#include <media/v4l2-ioctl.h>
 
 int v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev)
 {
@@ -32,7 +34,7 @@ int v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev)
 	INIT_LIST_HEAD(&fh->list);
 	set_bit(V4L2_FL_USES_V4L2_FH, &fh->vdev->flags);
 
-	return 0;
+	return v4l2_event_init(fh);
 }
 EXPORT_SYMBOL_GPL(v4l2_fh_init);
 
@@ -62,5 +64,7 @@ void v4l2_fh_exit(struct v4l2_fh *fh)
 		return;
 
 	fh->vdev = NULL;
+
+	v4l2_event_free(fh);
 }
 EXPORT_SYMBOL_GPL(v4l2_fh_exit);
diff --git a/include/media/v4l2-event.h b/include/media/v4l2-event.h
new file mode 100644
index 0000000..3b86177
--- /dev/null
+++ b/include/media/v4l2-event.h
@@ -0,0 +1,67 @@
+/*
+ * v4l2-event.h
+ *
+ * V4L2 events.
+ *
+ * Copyright (C) 2009--2010 Nokia Corporation.
+ *
+ * Contact: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
+ *
+ * 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>
+
+struct v4l2_fh;
+struct video_device;
+
+struct v4l2_kevent {
+	struct list_head	list;
+	struct v4l2_event	event;
+};
+
+struct v4l2_subscribed_event {
+	struct list_head	list;
+	u32			type;
+};
+
+struct v4l2_events {
+	wait_queue_head_t	wait;
+	struct list_head	subscribed; /* Subscribed events */
+	struct list_head	free; /* Events ready for use */
+	struct list_head	available; /* Dequeueable event */
+	unsigned int		navailable;
+	unsigned int		nallocated; /* Number of allocated events */
+	u32			sequence;
+};
+
+int v4l2_event_init(struct v4l2_fh *fh);
+int v4l2_event_alloc(struct v4l2_fh *fh, unsigned int n);
+void v4l2_event_free(struct v4l2_fh *fh);
+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);
+int v4l2_event_pending(struct v4l2_fh *fh);
+int v4l2_event_subscribe(struct v4l2_fh *fh,
+			 struct v4l2_event_subscription *sub);
+int v4l2_event_unsubscribe(struct v4l2_fh *fh,
+			   struct v4l2_event_subscription *sub);
+
+#endif /* V4L2_EVENT_H */
diff --git a/include/media/v4l2-fh.h b/include/media/v4l2-fh.h
index 410e86c..1d48c15 100644
--- a/include/media/v4l2-fh.h
+++ b/include/media/v4l2-fh.h
@@ -28,10 +28,12 @@
 #include <linux/list.h>
 
 struct video_device;
+struct v4l2_events;
 
 struct v4l2_fh {
 	struct list_head	list;
 	struct video_device	*vdev;
+	struct v4l2_events      *events; /* events, pending and subscribed */
 };
 
 int v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev);
-- 
1.5.6.5

[PATCH v8 5/6] V4L: Events: Support event handling in do_ioctl

[Sakari Ailus]

Add support for event handling to do_ioctl.

Signed-off-by: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
---
 drivers/media/video/v4l2-fh.c    |   11 +++++++-
 drivers/media/video/v4l2-ioctl.c |   50 ++++++++++++++++++++++++++++++++++++++
 include/media/v4l2-ioctl.h       |    7 +++++
 3 files changed, 67 insertions(+), 1 deletions(-)

diff --git a/drivers/media/video/v4l2-fh.c b/drivers/media/video/v4l2-fh.c
index aab2fb6..1423c44 100644
--- a/drivers/media/video/v4l2-fh.c
+++ b/drivers/media/video/v4l2-fh.c
@@ -34,7 +34,16 @@ int v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev)
 	INIT_LIST_HEAD(&fh->list);
 	set_bit(V4L2_FL_USES_V4L2_FH, &fh->vdev->flags);
 
-	return v4l2_event_init(fh);
+	/*
+	 * fh->events only needs to be initialized if the driver
+	 * supports the VIDIOC_SUBSCRIBE_EVENT ioctl.
+	 */
+	if (vdev->ioctl_ops && vdev->ioctl_ops->vidioc_subscribe_event)
+		return v4l2_event_init(fh);
+	else
+		fh->events = NULL;
+
+	return 0;
 }
 EXPORT_SYMBOL_GPL(v4l2_fh_init);
 
diff --git a/drivers/media/video/v4l2-ioctl.c b/drivers/media/video/v4l2-ioctl.c
index 34c7d6e..4ba22da 100644
--- a/drivers/media/video/v4l2-ioctl.c
+++ b/drivers/media/video/v4l2-ioctl.c
@@ -25,6 +25,8 @@
 #endif
 #include <media/v4l2-common.h>
 #include <media/v4l2-ioctl.h>
+#include <media/v4l2-fh.h>
+#include <media/v4l2-event.h>
 #include <media/v4l2-chip-ident.h>
 
 #define dbgarg(cmd, fmt, arg...) \
@@ -1944,7 +1946,55 @@ static long __video_do_ioctl(struct file *file,
 		}
 		break;
 	}
+	case VIDIOC_DQEVENT:
+	{
+		struct v4l2_event *ev = arg;
+
+		if (!ops->vidioc_subscribe_event)
+			break;
+
+		ret = v4l2_event_dequeue(fh, ev, file->f_flags & O_NONBLOCK);
+		if (ret < 0) {
+			dbgarg(cmd, "no pending events?");
+			break;
+		}
+		dbgarg(cmd,
+		       "pending=%d, type=0x%8.8x, sequence=%d, "
+		       "timestamp=%lu.%9.9lu ",
+		       ev->pending, ev->type, ev->sequence,
+		       ev->timestamp.tv_sec, ev->timestamp.tv_nsec);
+		break;
+	}
+	case VIDIOC_SUBSCRIBE_EVENT:
+	{
+		struct v4l2_event_subscription *sub = arg;
 
+		if (!ops->vidioc_subscribe_event)
+			break;
+
+		ret = ops->vidioc_subscribe_event(fh, sub);
+		if (ret < 0) {
+			dbgarg(cmd, "failed, ret=%ld", ret);
+			break;
+		}
+		dbgarg(cmd, "type=0x%8.8x", sub->type);
+		break;
+	}
+	case VIDIOC_UNSUBSCRIBE_EVENT:
+	{
+		struct v4l2_event_subscription *sub = arg;
+
+		if (!ops->vidioc_unsubscribe_event)
+			break;
+
+		ret = ops->vidioc_unsubscribe_event(fh, sub);
+		if (ret < 0) {
+			dbgarg(cmd, "failed, ret=%ld", ret);
+			break;
+		}
+		dbgarg(cmd, "type=0x%8.8x", sub->type);
+		break;
+	}
 	default:
 	{
 		if (!ops->vidioc_default)
diff --git a/include/media/v4l2-ioctl.h b/include/media/v4l2-ioctl.h
index e8ba0f2..06daa6e 100644
--- a/include/media/v4l2-ioctl.h
+++ b/include/media/v4l2-ioctl.h
@@ -21,6 +21,8 @@
 #include <linux/videodev2.h>
 #endif
 
+struct v4l2_fh;
+
 struct v4l2_ioctl_ops {
 	/* ioctl callbacks */
 
@@ -254,6 +256,11 @@ struct v4l2_ioctl_ops {
 	int (*vidioc_g_dv_timings) (struct file *file, void *fh,
 				    struct v4l2_dv_timings *timings);
 
+	int (*vidioc_subscribe_event)  (struct v4l2_fh *fh,
+					struct v4l2_event_subscription *sub);
+	int (*vidioc_unsubscribe_event)(struct v4l2_fh *fh,
+					struct v4l2_event_subscription *sub);
+
 	/* For other private ioctls */
 	long (*vidioc_default)	       (struct file *file, void *fh,
 					int cmd, void *arg);
-- 
1.5.6.5

[PATCH v8 6/6] V4L: Events: Add documentation

[Sakari Ailus]

Add documentation on how to use V4L2 events, both for V4L2 drivers and for
V4L2 applications.

Signed-off-by: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
---
 Documentation/DocBook/media-entities.tmpl          |    9 ++
 Documentation/DocBook/v4l/dev-event.xml            |   31 +++++
 Documentation/DocBook/v4l/v4l2.xml                 |    3 +
 Documentation/DocBook/v4l/vidioc-dqevent.xml       |  124 ++++++++++++++++++++
 .../DocBook/v4l/vidioc-subscribe-event.xml         |  104 ++++++++++++++++
 Documentation/video4linux/v4l2-framework.txt       |   60 ++++++++++
 6 files changed, 331 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/DocBook/v4l/dev-event.xml
 create mode 100644 Documentation/DocBook/v4l/vidioc-dqevent.xml
 create mode 100644 Documentation/DocBook/v4l/vidioc-subscribe-event.xml

diff --git a/Documentation/DocBook/media-entities.tmpl b/Documentation/DocBook/media-entities.tmpl
index c725cb8..770be3c 100644
--- a/Documentation/DocBook/media-entities.tmpl
+++ b/Documentation/DocBook/media-entities.tmpl
@@ -17,6 +17,7 @@
 <!ENTITY VIDIOC-DBG-G-REGISTER "<link linkend='vidioc-dbg-g-register'><constant>VIDIOC_DBG_G_REGISTER</constant></link>">
 <!ENTITY VIDIOC-DBG-S-REGISTER "<link linkend='vidioc-dbg-g-register'><constant>VIDIOC_DBG_S_REGISTER</constant></link>">
 <!ENTITY VIDIOC-DQBUF "<link linkend='vidioc-qbuf'><constant>VIDIOC_DQBUF</constant></link>">
+<!ENTITY VIDIOC-DQEVENT "<link linkend='vidioc-dqevent'><constant>VIDIOC_DQEVENT</constant></link>">
 <!ENTITY VIDIOC-ENCODER-CMD "<link linkend='vidioc-encoder-cmd'><constant>VIDIOC_ENCODER_CMD</constant></link>">
 <!ENTITY VIDIOC-ENUMAUDIO "<link linkend='vidioc-enumaudio'><constant>VIDIOC_ENUMAUDIO</constant></link>">
 <!ENTITY VIDIOC-ENUMAUDOUT "<link linkend='vidioc-enumaudioout'><constant>VIDIOC_ENUMAUDOUT</constant></link>">
@@ -60,6 +61,7 @@
 <!ENTITY VIDIOC-REQBUFS "<link linkend='vidioc-reqbufs'><constant>VIDIOC_REQBUFS</constant></link>">
 <!ENTITY VIDIOC-STREAMOFF "<link linkend='vidioc-streamon'><constant>VIDIOC_STREAMOFF</constant></link>">
 <!ENTITY VIDIOC-STREAMON "<link linkend='vidioc-streamon'><constant>VIDIOC_STREAMON</constant></link>">
+<!ENTITY VIDIOC-SUBSCRIBE-EVENT "<link linkend='vidioc-subscribe-event'><constant>VIDIOC_SUBSCRIBE_EVENT</constant></link>">
 <!ENTITY VIDIOC-S-AUDIO "<link linkend='vidioc-g-audio'><constant>VIDIOC_S_AUDIO</constant></link>">
 <!ENTITY VIDIOC-S-AUDOUT "<link linkend='vidioc-g-audioout'><constant>VIDIOC_S_AUDOUT</constant></link>">
 <!ENTITY VIDIOC-S-CROP "<link linkend='vidioc-g-crop'><constant>VIDIOC_S_CROP</constant></link>">
@@ -141,6 +143,8 @@
 <!ENTITY v4l2-enc-idx "struct&nbsp;<link linkend='v4l2-enc-idx'>v4l2_enc_idx</link>">
 <!ENTITY v4l2-enc-idx-entry "struct&nbsp;<link linkend='v4l2-enc-idx-entry'>v4l2_enc_idx_entry</link>">
 <!ENTITY v4l2-encoder-cmd "struct&nbsp;<link linkend='v4l2-encoder-cmd'>v4l2_encoder_cmd</link>">
+<!ENTITY v4l2-event "struct&nbsp;<link linkend='v4l2-event'>v4l2_event</link>">
+<!ENTITY v4l2-event-subscription "struct&nbsp;<link linkend='v4l2-event-subscription'>v4l2_event_subscription</link>">
 <!ENTITY v4l2-ext-control "struct&nbsp;<link linkend='v4l2-ext-control'>v4l2_ext_control</link>">
 <!ENTITY v4l2-ext-controls "struct&nbsp;<link linkend='v4l2-ext-controls'>v4l2_ext_controls</link>">
 <!ENTITY v4l2-fmtdesc "struct&nbsp;<link linkend='v4l2-fmtdesc'>v4l2_fmtdesc</link>">
@@ -200,6 +204,7 @@
 <!ENTITY sub-controls SYSTEM "v4l/controls.xml">
 <!ENTITY sub-dev-capture SYSTEM "v4l/dev-capture.xml">
 <!ENTITY sub-dev-codec SYSTEM "v4l/dev-codec.xml">
+<!ENTITY sub-dev-event SYSTEM "v4l/dev-event.xml">
 <!ENTITY sub-dev-effect SYSTEM "v4l/dev-effect.xml">
 <!ENTITY sub-dev-osd SYSTEM "v4l/dev-osd.xml">
 <!ENTITY sub-dev-output SYSTEM "v4l/dev-output.xml">
@@ -292,6 +297,8 @@
 <!ENTITY sub-v4l2grab-c SYSTEM "v4l/v4l2grab.c.xml">
 <!ENTITY sub-videodev2-h SYSTEM "v4l/videodev2.h.xml">
 <!ENTITY sub-v4l2 SYSTEM "v4l/v4l2.xml">
+<!ENTITY sub-dqevent SYSTEM "v4l/vidioc-dqevent.xml">
+<!ENTITY sub-subscribe-event SYSTEM "v4l/vidioc-subscribe-event.xml">
 <!ENTITY sub-intro SYSTEM "dvb/intro.xml">
 <!ENTITY sub-frontend SYSTEM "dvb/frontend.xml">
 <!ENTITY sub-dvbproperty SYSTEM "dvb/dvbproperty.xml">
@@ -381,3 +388,5 @@
 <!ENTITY reqbufs SYSTEM "v4l/vidioc-reqbufs.xml">
 <!ENTITY s-hw-freq-seek SYSTEM "v4l/vidioc-s-hw-freq-seek.xml">
 <!ENTITY streamon SYSTEM "v4l/vidioc-streamon.xml">
+<!ENTITY dqevent SYSTEM "v4l/vidioc-dqevent.xml">
+<!ENTITY subscribe_event SYSTEM "v4l/vidioc-subscribe-event.xml">
diff --git a/Documentation/DocBook/v4l/dev-event.xml b/Documentation/DocBook/v4l/dev-event.xml
new file mode 100644
index 0000000..be5a98f
--- /dev/null
+++ b/Documentation/DocBook/v4l/dev-event.xml
@@ -0,0 +1,31 @@
+  <title>Event Interface</title>
+
+  <para>The V4L2 event interface provides means for user to get
+  immediately notified on certain conditions taking place on a device.
+  This might include start of frame or loss of signal events, for
+  example.
+  </para>
+
+  <para>To receive events, the events the user is interested in first must
+  be subscribed using the &VIDIOC-SUBSCRIBE-EVENT; ioctl. Once an event is
+  subscribed, the events of subscribed types are dequeueable using the
+  &VIDIOC-DQEVENT; ioctl. Events may be unsubscribed using
+  VIDIOC_UNSUBSCRIBE_EVENT ioctl. The special event type V4L2_EVENT_ALL may
+  be used to unsubscribe all the events the driver supports.</para>
+
+  <para>The event subscriptions and event queues are specific to file
+  handles. Subscribing an event on one file handle does not affect
+  other file handles.
+  </para>
+
+  <para>The information on dequeueable events is obtained by using select or
+  poll system calls on video devices. The V4L2 events use POLLPRI events on
+  poll system call and exceptions on select system call.  </para>
+
+  <!--
+Local Variables:
+mode: sgml
+sgml-parent-document: "v4l2.sgml"
+indent-tabs-mode: nil
+End:
+  -->
diff --git a/Documentation/DocBook/v4l/v4l2.xml b/Documentation/DocBook/v4l/v4l2.xml
index 060105a..9737243 100644
--- a/Documentation/DocBook/v4l/v4l2.xml
+++ b/Documentation/DocBook/v4l/v4l2.xml
@@ -401,6 +401,7 @@ and discussions on the V4L mailing list.</revremark>
     <section id="ttx"> &sub-dev-teletext; </section>
     <section id="radio"> &sub-dev-radio; </section>
     <section id="rds"> &sub-dev-rds; </section>
+    <section id="event"> &sub-dev-event; </section>
   </chapter>
 
   <chapter id="driver">
@@ -426,6 +427,7 @@ and discussions on the V4L mailing list.</revremark>
     &sub-cropcap;
     &sub-dbg-g-chip-ident;
     &sub-dbg-g-register;
+    &sub-dqevent;
     &sub-encoder-cmd;
     &sub-enumaudio;
     &sub-enumaudioout;
@@ -467,6 +469,7 @@ and discussions on the V4L mailing list.</revremark>
     &sub-reqbufs;
     &sub-s-hw-freq-seek;
     &sub-streamon;
+    &sub-subscribe-event;
     <!-- End of ioctls. -->
     &sub-mmap;
     &sub-munmap;
diff --git a/Documentation/DocBook/v4l/vidioc-dqevent.xml b/Documentation/DocBook/v4l/vidioc-dqevent.xml
new file mode 100644
index 0000000..eb45c16
--- /dev/null
+++ b/Documentation/DocBook/v4l/vidioc-dqevent.xml
@@ -0,0 +1,124 @@
+<refentry id="vidioc-dqevent">
+  <refmeta>
+    <refentrytitle>ioctl VIDIOC_DQEVENT</refentrytitle>
+    &manvol;
+  </refmeta>
+
+  <refnamediv>
+    <refname>VIDIOC_DQEVENT</refname>
+    <refpurpose>Dequeue event</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <funcsynopsis>
+      <funcprototype>
+	<funcdef>int <function>ioctl</function></funcdef>
+	<paramdef>int <parameter>fd</parameter></paramdef>
+	<paramdef>int <parameter>request</parameter></paramdef>
+	<paramdef>struct v4l2_event
+*<parameter>argp</parameter></paramdef>
+      </funcprototype>
+    </funcsynopsis>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Arguments</title>
+
+    <variablelist>
+      <varlistentry>
+	<term><parameter>fd</parameter></term>
+	<listitem>
+	  <para>&fd;</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><parameter>request</parameter></term>
+	<listitem>
+	  <para>VIDIOC_DQEVENT</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><parameter>argp</parameter></term>
+	<listitem>
+	  <para></para>
+	</listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+
+  <refsect1>
+    <title>Description</title>
+
+    <para>Dequeue an event from a video device. No input is required
+    for this ioctl. All the fields of the &v4l2-event; structure are
+    filled by the driver. The file handle will also receive exceptions
+    which the application may get by e.g. using the select system
+    call.</para>
+
+    <table frame="none" pgwide="1" id="v4l2-event">
+      <title>struct <structname>v4l2_event</structname></title>
+      <tgroup cols="4">
+	&cs-str;
+	<tbody valign="top">
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>type</structfield></entry>
+            <entry></entry>
+	    <entry>Type of the event.</entry>
+	  </row>
+	  <row>
+	    <entry>union</entry>
+	    <entry><structfield>u</structfield></entry>
+            <entry></entry>
+	    <entry></entry>
+	  </row>
+	  <row>
+	    <entry></entry>
+	    <entry>__u8</entry>
+            <entry><structfield>data</structfield>[64]</entry>
+	    <entry>Event data. Defined by the event type. The union
+            should be used to define easily accessible type for
+            events.</entry>
+	  </row>
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>pending</structfield></entry>
+            <entry></entry>
+	    <entry>Number of pending events excluding this one.</entry>
+	  </row>
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>sequence</structfield></entry>
+            <entry></entry>
+	    <entry>Event sequence number. The sequence number is
+	    incremented for every subscribed event that takes place.
+	    If sequence numbers are not contiguous it means that
+	    events have been lost.
+	    </entry>
+	  </row>
+	  <row>
+	    <entry>struct timeval</entry>
+	    <entry><structfield>timestamp</structfield></entry>
+            <entry></entry>
+	    <entry>Event timestamp.</entry>
+	  </row>
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>reserved</structfield>[9]</entry>
+            <entry></entry>
+	    <entry>Reserved for future extensions. Drivers must set
+	    the array to zero.</entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+
+  </refsect1>
+</refentry>
+<!--
+Local Variables:
+mode: sgml
+sgml-parent-document: "v4l2.sgml"
+indent-tabs-mode: nil
+End:
+-->
diff --git a/Documentation/DocBook/v4l/vidioc-subscribe-event.xml b/Documentation/DocBook/v4l/vidioc-subscribe-event.xml
new file mode 100644
index 0000000..71ab88c
--- /dev/null
+++ b/Documentation/DocBook/v4l/vidioc-subscribe-event.xml
@@ -0,0 +1,104 @@
+<refentry id="vidioc-subscribe-event">
+  <refmeta>
+    <refentrytitle>ioctl VIDIOC_SUBSCRIBE_EVENT, VIDIOC_UNSUBSCRIBE_EVENT</refentrytitle>
+    &manvol;
+  </refmeta>
+
+  <refnamediv>
+    <refname>VIDIOC_SUBSCRIBE_EVENT, VIDIOC_UNSUBSCRIBE_EVENT</refname>
+    <refpurpose>Subscribe or unsubscribe event</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <funcsynopsis>
+      <funcprototype>
+	<funcdef>int <function>ioctl</function></funcdef>
+	<paramdef>int <parameter>fd</parameter></paramdef>
+	<paramdef>int <parameter>request</parameter></paramdef>
+	<paramdef>struct v4l2_event_subscription
+*<parameter>argp</parameter></paramdef>
+      </funcprototype>
+    </funcsynopsis>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Arguments</title>
+
+    <variablelist>
+      <varlistentry>
+	<term><parameter>fd</parameter></term>
+	<listitem>
+	  <para>&fd;</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><parameter>request</parameter></term>
+	<listitem>
+	  <para>VIDIOC_SUBSCRIBE_EVENT, VIDIOC_UNSUBSCRIBE_EVENT</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><parameter>argp</parameter></term>
+	<listitem>
+	  <para></para>
+	</listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+
+  <refsect1>
+    <title>Description</title>
+
+    <para>Subscribe or unsubscribe V4L2 event. Subscribed events are
+    dequeued by using the &VIDIOC-DQEVENT; ioctl.</para>
+
+    <table frame="none" pgwide="1" id="v4l2-event-subscription">
+      <title>struct <structname>v4l2_event_subscription</structname></title>
+      <tgroup cols="3">
+	&cs-str;
+	<tbody valign="top">
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>type</structfield></entry>
+	    <entry>Type of the event.</entry>
+	  </row>
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>reserved</structfield>[7]</entry>
+	    <entry>Reserved for future extensions. Drivers and applications
+	    must set the array to zero.</entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+
+    <table frame="none" pgwide="1" id="event-type">
+      <title>Event Types</title>
+      <tgroup cols="3">
+	&cs-def;
+	<tbody valign="top">
+	  <row>
+	    <entry><constant>V4L2_EVENT_ALL</constant></entry>
+	    <entry>0</entry>
+	    <entry>All events. V4L2_EVENT_ALL is valid only for
+	    VIDIOC_UNSUBSCRIBE_EVENT for unsubscribing all events at once.
+	    </entry>
+	  </row>
+	  <row>
+	    <entry><constant>V4L2_EVENT_PRIVATE_START</constant></entry>
+	    <entry>0x08000000</entry>
+	    <entry>Base event number for driver-private events.</entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+
+  </refsect1>
+</refentry>
+<!--
+Local Variables:
+mode: sgml
+sgml-parent-document: "v4l2.sgml"
+indent-tabs-mode: nil
+End:
+-->
diff --git a/Documentation/video4linux/v4l2-framework.txt b/Documentation/video4linux/v4l2-framework.txt
index bfaf0c5..0a22969 100644
--- a/Documentation/video4linux/v4l2-framework.txt
+++ b/Documentation/video4linux/v4l2-framework.txt
@@ -732,3 +732,63 @@ Useful functions:
 The users of v4l2_fh know whether a driver uses v4l2_fh as its
 file->private_data pointer by testing the V4L2_FL_USES_V4L2_FH bit in
 video_device->flags.
+
+V4L2 events
+-----------
+
+The V4L2 events provide a generic way to pass events to user space.
+The driver must use v4l2_fh to be able to support V4L2 events.
+
+Useful functions:
+
+- v4l2_event_alloc()
+
+  To use events, the driver must allocate events for the file handle. By
+  calling the function more than once, the driver may assure that at least n
+  events in total have been allocated. The function may not be called in
+  atomic context.
+
+- v4l2_event_queue()
+
+  Queue events to video device. The driver's only responsibility is to fill
+  in the type and the data fields. The other fields will be filled in by
+  V4L2.
+
+- v4l2_event_subscribe()
+
+  The video_device->ioctl_ops->vidioc_subscribe_event must check the driver
+  is able to produce events with specified event id. Then it calls
+  v4l2_event_subscribe() to subscribe the event.
+
+- v4l2_event_unsubscribe()
+
+  vidioc_unsubscribe_event in struct v4l2_ioctl_ops. A driver may use
+  v4l2_event_unsubscribe() directly unless it wants to be involved in
+  unsubscription process.
+
+  The special type V4L2_EVENT_ALL may be used to unsubscribe all events. The
+  drivers may want to handle this in a special way.
+
+- v4l2_event_pending()
+
+  Returns the number of pending events. Useful when implementing poll.
+
+Drivers do not initialise events directly. The events are initialised
+through v4l2_fh_init() if video_device->ioctl_ops->vidioc_subscribe_event is
+non-NULL. This *MUST* be performed in the driver's
+v4l2_file_operations->open() handler.
+
+Events are delivered to user space through the poll system call. The driver
+can use v4l2_fh->events->wait wait_queue_head_t as the argument for
+poll_wait().
+
+There are standard and private events. New standard events must use the
+smallest available event type. The drivers must allocate their events from
+their own class starting from class base. Class base is
+V4L2_EVENT_PRIVATE_START + n * 1000 where n is the lowest available number.
+The first event type in the class is reserved for future use, so the first
+available event type is 'class base + 1'.
+
+An example on how the V4L2 events may be used can be found in the OMAP
+3 ISP driver available at <URL:http://gitorious.org/omap3camera> as of
+writing this.
-- 
1.5.6.5

V4L2 file handle and event patches

[Sakari Ailus]

Sakari Ailus wrote:
> Hi,
> 
> Here's the tenth version of the V4L2 file handle and event interface
> patchset.
> 
> The patchset has been tested with the OMAP 3 ISP driver. Patches for
> OMAP 3 ISP are not part of this patchset but are available in Gitorious
> (branch is called event):
> 
> 	git://gitorious.org/omap3camera/mainline.git event
> 
> The patchset I'm posting now is against the v4l-dvb tree instead of
> linux-omap. The omap3camera tree thus has a slightly different
> version of these patches (just Makefiles) due to different baselines.

Hi Mauro,

What is your opinion on the file handle and event patchset? Could we get
them integrated for 2.6.34? Hans Verkuil as well as many others have no
more comments on them.

The patchset in question is v8.

Sincerely,

-- 
Sakari Ailus
sakari.ailus@maxwell.research.nokia.com

Re: [PATCH v8 4/6] V4L: Events: Add backend

[Sakari Ailus]

Sakari Ailus wrote:
> Add event handling backend to V4L2. The backend handles event subscription
> and delivery to file handles. Event subscriptions are based on file handle.
> Events may be delivered to all subscribed file handles on a device
> independent of where they originate from.

Hi,

Some style problems accidentally slipped into this one. I'm not
resending the whole set, just the broken patch, now v8.1.

-- 
Sakari Ailus
sakari.ailus@maxwell.research.nokia.com

[PATCH v8.1 4/6] V4L: Events: Add backend

[Sakari Ailus]

Add event handling backend to V4L2. The backend handles event subscription
and delivery to file handles. Event subscriptions are based on file handle.
Events may be delivered to all subscribed file handles on a device
independent of where they originate from.

Signed-off-by: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
---
 drivers/media/video/Makefile     |    3 +-
 drivers/media/video/v4l2-event.c |  289 ++++++++++++++++++++++++++++++++++++++
 drivers/media/video/v4l2-fh.c    |    6 +-
 include/media/v4l2-event.h       |   67 +++++++++
 include/media/v4l2-fh.h          |    2 +
 5 files changed, 365 insertions(+), 2 deletions(-)
 create mode 100644 drivers/media/video/v4l2-event.c
 create mode 100644 include/media/v4l2-event.h

diff --git a/drivers/media/video/Makefile b/drivers/media/video/Makefile
index 14bf69a..b84abfe 100644
--- a/drivers/media/video/Makefile
+++ b/drivers/media/video/Makefile
@@ -10,7 +10,8 @@ stkwebcam-objs	:=	stk-webcam.o stk-sensor.o
 
 omap2cam-objs	:=	omap24xxcam.o omap24xxcam-dma.o
 
-videodev-objs	:=	v4l2-dev.o v4l2-ioctl.o v4l2-device.o v4l2-fh.o
+videodev-objs	:=	v4l2-dev.o v4l2-ioctl.o v4l2-device.o v4l2-fh.o \
+			v4l2-event.o
 
 # V4L2 core modules
 
diff --git a/drivers/media/video/v4l2-event.c b/drivers/media/video/v4l2-event.c
new file mode 100644
index 0000000..a0cadeb
--- /dev/null
+++ b/drivers/media/video/v4l2-event.c
@@ -0,0 +1,289 @@
+/*
+ * v4l2-event.c
+ *
+ * V4L2 events.
+ *
+ * Copyright (C) 2009--2010 Nokia Corporation.
+ *
+ * Contact: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
+ *
+ * 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
+ */
+
+#include <media/v4l2-dev.h>
+#include <media/v4l2-fh.h>
+#include <media/v4l2-event.h>
+
+#include <linux/sched.h>
+
+int v4l2_event_init(struct v4l2_fh *fh)
+{
+	fh->events = kzalloc(sizeof(*fh->events), GFP_KERNEL);
+	if (fh->events == NULL)
+		return -ENOMEM;
+
+	init_waitqueue_head(&fh->events->wait);
+
+	INIT_LIST_HEAD(&fh->events->free);
+	INIT_LIST_HEAD(&fh->events->available);
+	INIT_LIST_HEAD(&fh->events->subscribed);
+
+	fh->events->sequence = -1;
+
+	return 0;
+}
+
+int v4l2_event_alloc(struct v4l2_fh *fh, unsigned int n)
+{
+	struct v4l2_events *events = fh->events;
+	unsigned long flags;
+
+	if (!events) {
+		WARN_ON(1);
+		return -ENOMEM;
+	}
+
+	while (events->nallocated < n) {
+		struct v4l2_kevent *kev;
+
+		kev = kzalloc(sizeof(*kev), GFP_KERNEL);
+		if (kev == NULL)
+			return -ENOMEM;
+
+		spin_lock_irqsave(&fh->vdev->fh_lock, flags);
+		list_add_tail(&kev->list, &events->free);
+		events->nallocated++;
+		spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(v4l2_event_alloc);
+
+#define list_kfree(list, type, member)				\
+	while (!list_empty(list)) {				\
+		type *hi;					\
+		hi = list_first_entry(list, type, member);	\
+		list_del(&hi->member);				\
+		kfree(hi);					\
+	}
+
+void v4l2_event_free(struct v4l2_fh *fh)
+{
+	struct v4l2_events *events = fh->events;
+
+	if (!events)
+		return;
+
+	list_kfree(&events->free, struct v4l2_kevent, list);
+	list_kfree(&events->available, struct v4l2_kevent, list);
+	list_kfree(&events->subscribed, struct v4l2_subscribed_event, list);
+
+	kfree(events);
+	fh->events = NULL;
+}
+EXPORT_SYMBOL_GPL(v4l2_event_free);
+
+static int __v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event)
+{
+	struct v4l2_events *events = fh->events;
+	struct v4l2_kevent *kev;
+	unsigned long flags;
+
+	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
+
+	if (list_empty(&events->available)) {
+		spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
+		return -ENOENT;
+	}
+
+	WARN_ON(events->navailable == 0);
+
+	kev = list_first_entry(&events->available, struct v4l2_kevent, list);
+	list_move(&kev->list, &events->free);
+	events->navailable--;
+
+	kev->event.pending = events->navailable;
+	*event = kev->event;
+
+	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
+
+	return 0;
+}
+
+int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
+		       int nonblocking)
+{
+	struct v4l2_events *events = fh->events;
+	int ret;
+
+	if (nonblocking)
+		return __v4l2_event_dequeue(fh, event);
+
+	do {
+		ret = wait_event_interruptible(events->wait,
+					       events->navailable != 0);
+		if (ret < 0)
+			return ret;
+
+		ret = __v4l2_event_dequeue(fh, event);
+	} while (ret == -ENOENT);
+
+	return ret;
+}
+
+/* Caller must hold fh->event->lock! */
+static struct v4l2_subscribed_event *v4l2_event_subscribed(
+	struct v4l2_fh *fh, u32 type)
+{
+	struct v4l2_events *events = fh->events;
+	struct v4l2_subscribed_event *sev;
+
+	WARN_ON(!spin_is_locked(&fh->vdev->fh_lock));
+
+	list_for_each_entry(sev, &events->subscribed, list) {
+		if (sev->type == type)
+			return sev;
+	}
+
+	return NULL;
+}
+
+void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev)
+{
+	struct v4l2_fh *fh;
+	unsigned long flags;
+	struct timespec timestamp;
+
+	ktime_get_ts(&timestamp);
+
+	spin_lock_irqsave(&vdev->fh_lock, flags);
+
+	list_for_each_entry(fh, &vdev->fh_list, list) {
+		struct v4l2_events *events = fh->events;
+		struct v4l2_kevent *kev;
+
+		/* Are we subscribed? */
+		if (!v4l2_event_subscribed(fh, ev->type))
+			continue;
+
+		/* Increase event sequence number on fh. */
+		events->sequence++;
+
+		/* Do we have any free events? */
+		if (list_empty(&events->free))
+			continue;
+
+		/* Take one and fill it. */
+		kev = list_first_entry(&events->free, struct v4l2_kevent, list);
+		kev->event.type = ev->type;
+		kev->event.u = ev->u;
+		kev->event.timestamp = timestamp;
+		kev->event.sequence = events->sequence;
+		list_move_tail(&kev->list, &events->available);
+
+		events->navailable++;
+
+		wake_up_all(&events->wait);
+	}
+
+	spin_unlock_irqrestore(&vdev->fh_lock, flags);
+}
+EXPORT_SYMBOL_GPL(v4l2_event_queue);
+
+int v4l2_event_pending(struct v4l2_fh *fh)
+{
+	return fh->events->navailable;
+}
+EXPORT_SYMBOL_GPL(v4l2_event_pending);
+
+int v4l2_event_subscribe(struct v4l2_fh *fh,
+			 struct v4l2_event_subscription *sub)
+{
+	struct v4l2_events *events = fh->events;
+	struct v4l2_subscribed_event *sev;
+	unsigned long flags;
+
+	if (fh->events == NULL) {
+		WARN_ON(1);
+		return -ENOMEM;
+	}
+
+	sev = kmalloc(sizeof(*sev), GFP_KERNEL);
+	if (!sev)
+		return -ENOMEM;
+
+	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
+
+	if (v4l2_event_subscribed(fh, sub->type) == NULL) {
+		INIT_LIST_HEAD(&sev->list);
+		sev->type = sub->type;
+
+		list_add(&sev->list, &events->subscribed);
+		sev = NULL;
+	}
+
+	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
+
+	kfree(sev);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
+
+static void v4l2_event_unsubscribe_all(struct v4l2_fh *fh)
+{
+	struct v4l2_events *events = fh->events;
+	struct v4l2_subscribed_event *sev;
+	unsigned long flags;
+
+	do {
+		sev = NULL;
+
+		spin_lock_irqsave(&fh->vdev->fh_lock, flags);
+		if (!list_empty(&events->subscribed)) {
+			sev = list_first_entry(&events->subscribed,
+				       struct v4l2_subscribed_event, list);
+			list_del(&sev->list);
+		}
+		spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
+		kfree(sev);
+	} while (sev);
+}
+
+int v4l2_event_unsubscribe(struct v4l2_fh *fh,
+			   struct v4l2_event_subscription *sub)
+{
+	struct v4l2_subscribed_event *sev;
+	unsigned long flags;
+
+	if (sub->type == V4L2_EVENT_ALL) {
+		v4l2_event_unsubscribe_all(fh);
+		return 0;
+	}
+
+	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
+
+	sev = v4l2_event_subscribed(fh, sub->type);
+	if (sev != NULL)
+		list_del(&sev->list);
+
+	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
+
+	kfree(sev);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe);
diff --git a/drivers/media/video/v4l2-fh.c b/drivers/media/video/v4l2-fh.c
index 93ea0af..aab2fb6 100644
--- a/drivers/media/video/v4l2-fh.c
+++ b/drivers/media/video/v4l2-fh.c
@@ -25,6 +25,8 @@
 #include <linux/bitops.h>
 #include <media/v4l2-dev.h>
 #include <media/v4l2-fh.h>
+#include <media/v4l2-event.h>
+#include <media/v4l2-ioctl.h>
 
 int v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev)
 {
@@ -32,7 +34,7 @@ int v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev)
 	INIT_LIST_HEAD(&fh->list);
 	set_bit(V4L2_FL_USES_V4L2_FH, &fh->vdev->flags);
 
-	return 0;
+	return v4l2_event_init(fh);
 }
 EXPORT_SYMBOL_GPL(v4l2_fh_init);
 
@@ -62,5 +64,7 @@ void v4l2_fh_exit(struct v4l2_fh *fh)
 		return;
 
 	fh->vdev = NULL;
+
+	v4l2_event_free(fh);
 }
 EXPORT_SYMBOL_GPL(v4l2_fh_exit);
diff --git a/include/media/v4l2-event.h b/include/media/v4l2-event.h
new file mode 100644
index 0000000..3b86177
--- /dev/null
+++ b/include/media/v4l2-event.h
@@ -0,0 +1,67 @@
+/*
+ * v4l2-event.h
+ *
+ * V4L2 events.
+ *
+ * Copyright (C) 2009--2010 Nokia Corporation.
+ *
+ * Contact: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
+ *
+ * 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>
+
+struct v4l2_fh;
+struct video_device;
+
+struct v4l2_kevent {
+	struct list_head	list;
+	struct v4l2_event	event;
+};
+
+struct v4l2_subscribed_event {
+	struct list_head	list;
+	u32			type;
+};
+
+struct v4l2_events {
+	wait_queue_head_t	wait;
+	struct list_head	subscribed; /* Subscribed events */
+	struct list_head	free; /* Events ready for use */
+	struct list_head	available; /* Dequeueable event */
+	unsigned int		navailable;
+	unsigned int		nallocated; /* Number of allocated events */
+	u32			sequence;
+};
+
+int v4l2_event_init(struct v4l2_fh *fh);
+int v4l2_event_alloc(struct v4l2_fh *fh, unsigned int n);
+void v4l2_event_free(struct v4l2_fh *fh);
+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);
+int v4l2_event_pending(struct v4l2_fh *fh);
+int v4l2_event_subscribe(struct v4l2_fh *fh,
+			 struct v4l2_event_subscription *sub);
+int v4l2_event_unsubscribe(struct v4l2_fh *fh,
+			   struct v4l2_event_subscription *sub);
+
+#endif /* V4L2_EVENT_H */
diff --git a/include/media/v4l2-fh.h b/include/media/v4l2-fh.h
index 410e86c..1d48c15 100644
--- a/include/media/v4l2-fh.h
+++ b/include/media/v4l2-fh.h
@@ -28,10 +28,12 @@
 #include <linux/list.h>
 
 struct video_device;
+struct v4l2_events;
 
 struct v4l2_fh {
 	struct list_head	list;
 	struct video_device	*vdev;
+	struct v4l2_events      *events; /* events, pending and subscribed */
 };
 
 int v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev);
-- 
1.5.6.5

Re: [PATCH v8 0/6] V4L2 file handles and event interface

[Mauro Carvalho Chehab]

Sakari,

As usual, I'm marking those patches as RFC. Please add them on some tree
and ask me to pull from it, when you think that event interface is ready 
for upstream merge.

Cheers,
Mauro.

Sakari Ailus wrote:
> Hi,
> 
> Here's the tenth version of the V4L2 file handle and event interface
> patchset.
> 
> The patchset has been tested with the OMAP 3 ISP driver. Patches for
> OMAP 3 ISP are not part of this patchset but are available in Gitorious
> (branch is called event):
> 
> 	git://gitorious.org/omap3camera/mainline.git event
> 
> The patchset I'm posting now is against the v4l-dvb tree instead of
> linux-omap. The omap3camera tree thus has a slightly different
> version of these patches (just Makefiles) due to different baselines.
> 
> Some more comments from Hans and Randy. There are only improvements in
> documentation this time.
> 
> Comments are welcome as always.
> 
> Cheers,
> 


-- 

Cheers,
Mauro