V4L/DVB: V4L: Events: Add backend

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>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 290 insertions, 0 deletions

diff --git a/drivers/media/video/v4l2-event.c b/drivers/media/video/v4l2-event.c
new file mode 100644
index 0000000..170e40f
--- /dev/null
+++ b/drivers/media/video/v4l2-event.c
@@ -0,0 +1,290 @@
+/*
+ * 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>
+#include <linux/slab.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);