[media] v4l2-ctrls: add control events

Whenever a control changes value or state an event is sent to anyone
that subscribed to it.

This functionality is useful for control panels but also for applications
that need to wait for (usually status) controls to change value.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 95 insertions, 35 deletions

diff --git a/drivers/media/video/v4l2-event.c b/drivers/media/video/v4l2-event.c
index 69fd343d4774..670f2f834e6a 100644
--- a/drivers/media/video/v4l2-event.c
+++ b/drivers/media/video/v4l2-event.c
@@ -25,10 +25,13 @@
 #include <media/v4l2-dev.h>
 #include <media/v4l2-fh.h>
 #include <media/v4l2-event.h>
+#include <media/v4l2-ctrls.h>
 
 #include <linux/sched.h>
 #include <linux/slab.h>
 
+static void v4l2_event_unsubscribe_all(struct v4l2_fh *fh);
+
 int v4l2_event_init(struct v4l2_fh *fh)
 {
 	fh->events = kzalloc(sizeof(*fh->events), GFP_KERNEL);
@@ -91,7 +94,7 @@ void v4l2_event_free(struct v4l2_fh *fh)
 
 	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);
+	v4l2_event_unsubscribe_all(fh);
 
 	kfree(events);
 	fh->events = NULL;
@@ -154,9 +157,9 @@ int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
 }
 EXPORT_SYMBOL_GPL(v4l2_event_dequeue);
 
-/* Caller must hold fh->event->lock! */
+/* Caller must hold fh->vdev->fh_lock! */
 static struct v4l2_subscribed_event *v4l2_event_subscribed(
-	struct v4l2_fh *fh, u32 type)
+		struct v4l2_fh *fh, u32 type, u32 id)
 {
 	struct v4l2_events *events = fh->events;
 	struct v4l2_subscribed_event *sev;
@@ -164,13 +167,46 @@ static struct v4l2_subscribed_event *v4l2_event_subscribed(
 	assert_spin_locked(&fh->vdev->fh_lock);
 
 	list_for_each_entry(sev, &events->subscribed, list) {
-		if (sev->type == type)
+		if (sev->type == type && sev->id == id)
 			return sev;
 	}
 
 	return NULL;
 }
 
+static void __v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev,
+		const struct timespec *ts)
+{
+	struct v4l2_events *events = fh->events;
+	struct v4l2_subscribed_event *sev;
+	struct v4l2_kevent *kev;
+
+	/* Are we subscribed? */
+	sev = v4l2_event_subscribed(fh, ev->type, ev->id);
+	if (sev == NULL)
+		return;
+
+	/* Increase event sequence number on fh. */
+	events->sequence++;
+
+	/* Do we have any free events? */
+	if (list_empty(&events->free))
+		return;
+
+	/* 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.id = ev->id;
+	kev->event.timestamp = *ts;
+	kev->event.sequence = events->sequence;
+	list_move_tail(&kev->list, &events->available);
+
+	events->navailable++;
+
+	wake_up_all(&events->wait);
+}
+
 void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev)
 {
 	struct v4l2_fh *fh;
@@ -182,37 +218,26 @@ void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev)
 	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);
+		__v4l2_event_queue_fh(fh, ev, &timestamp);
 	}
 
 	spin_unlock_irqrestore(&vdev->fh_lock, flags);
 }
 EXPORT_SYMBOL_GPL(v4l2_event_queue);
 
+void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev)
+{
+	unsigned long flags;
+	struct timespec timestamp;
+
+	ktime_get_ts(&timestamp);
+
+	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
+	__v4l2_event_queue_fh(fh, ev, &timestamp);
+	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
+}
+EXPORT_SYMBOL_GPL(v4l2_event_queue_fh);
+
 int v4l2_event_pending(struct v4l2_fh *fh)
 {
 	return fh->events->navailable;
@@ -223,7 +248,9 @@ int v4l2_event_subscribe(struct v4l2_fh *fh,
 			 struct v4l2_event_subscription *sub)
 {
 	struct v4l2_events *events = fh->events;
-	struct v4l2_subscribed_event *sev;
+	struct v4l2_subscribed_event *sev, *found_ev;
+	struct v4l2_ctrl *ctrl = NULL;
+	struct v4l2_ctrl_fh *ctrl_fh = NULL;
 	unsigned long flags;
 
 	if (fh->events == NULL) {
@@ -231,15 +258,31 @@ int v4l2_event_subscribe(struct v4l2_fh *fh,
 		return -ENOMEM;
 	}
 
+	if (sub->type == V4L2_EVENT_CTRL) {
+		ctrl = v4l2_ctrl_find(fh->ctrl_handler, sub->id);
+		if (ctrl == NULL)
+			return -EINVAL;
+	}
+
 	sev = kmalloc(sizeof(*sev), GFP_KERNEL);
 	if (!sev)
 		return -ENOMEM;
+	if (ctrl) {
+		ctrl_fh = kzalloc(sizeof(*ctrl_fh), GFP_KERNEL);
+		if (!ctrl_fh) {
+			kfree(sev);
+			return -ENOMEM;
+		}
+		ctrl_fh->fh = fh;
+	}
 
 	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 
-	if (v4l2_event_subscribed(fh, sub->type) == NULL) {
+	found_ev = v4l2_event_subscribed(fh, sub->type, sub->id);
+	if (!found_ev) {
 		INIT_LIST_HEAD(&sev->list);
 		sev->type = sub->type;
+		sev->id = sub->id;
 
 		list_add(&sev->list, &events->subscribed);
 		sev = NULL;
@@ -247,6 +290,14 @@ int v4l2_event_subscribe(struct v4l2_fh *fh,
 
 	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 
+	/* v4l2_ctrl_add_fh uses a mutex, so do this outside the spin lock */
+	if (ctrl) {
+		if (found_ev)
+			kfree(ctrl_fh);
+		else
+			v4l2_ctrl_add_fh(fh->ctrl_handler, ctrl_fh, sub);
+	}
+
 	kfree(sev);
 
 	return 0;
@@ -256,6 +307,7 @@ EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
 static void v4l2_event_unsubscribe_all(struct v4l2_fh *fh)
 {
 	struct v4l2_events *events = fh->events;
+	struct v4l2_event_subscription sub;
 	struct v4l2_subscribed_event *sev;
 	unsigned long flags;
 
@@ -265,11 +317,13 @@ static void v4l2_event_unsubscribe_all(struct v4l2_fh *fh)
 		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);
+					struct v4l2_subscribed_event, list);
+			sub.type = sev->type;
+			sub.id = sev->id;
 		}
 		spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
-		kfree(sev);
+		if (sev)
+			v4l2_event_unsubscribe(fh, &sub);
 	} while (sev);
 }
 
@@ -286,11 +340,17 @@ int v4l2_event_unsubscribe(struct v4l2_fh *fh,
 
 	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 
-	sev = v4l2_event_subscribed(fh, sub->type);
+	sev = v4l2_event_subscribed(fh, sub->type, sub->id);
 	if (sev != NULL)
 		list_del(&sev->list);
 
 	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
+	if (sev->type == V4L2_EVENT_CTRL) {
+		struct v4l2_ctrl *ctrl = v4l2_ctrl_find(fh->ctrl_handler, sev->id);
+
+		if (ctrl)
+			v4l2_ctrl_del_fh(ctrl, fh);
+	}
 
 	kfree(sev);