[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>

3 files changed, 206 insertions, 43 deletions

diff --git a/drivers/media/video/v4l2-ctrls.c b/drivers/media/video/v4l2-ctrls.c
index 70dbeeef6a2..5f316667c14 100644
--- a/drivers/media/video/v4l2-ctrls.c
+++ b/drivers/media/video/v4l2-ctrls.c
@@ -23,6 +23,7 @@
 #include <media/v4l2-ioctl.h>
 #include <media/v4l2-device.h>
 #include <media/v4l2-ctrls.h>
+#include <media/v4l2-event.h>
 #include <media/v4l2-dev.h>
 
 #define has_op(master, op) \
@@ -556,6 +557,41 @@ static bool type_is_int(const struct v4l2_ctrl *ctrl)
 	}
 }
 
+static void fill_event(struct v4l2_event *ev, struct v4l2_ctrl *ctrl, u32 changes)
+{
+	memset(ev->reserved, 0, sizeof(ev->reserved));
+	ev->type = V4L2_EVENT_CTRL;
+	ev->id = ctrl->id;
+	ev->u.ctrl.changes = changes;
+	ev->u.ctrl.type = ctrl->type;
+	ev->u.ctrl.flags = ctrl->flags;
+	if (ctrl->type == V4L2_CTRL_TYPE_STRING)
+		ev->u.ctrl.value64 = 0;
+	else
+		ev->u.ctrl.value64 = ctrl->cur.val64;
+	ev->u.ctrl.minimum = ctrl->minimum;
+	ev->u.ctrl.maximum = ctrl->maximum;
+	if (ctrl->type == V4L2_CTRL_TYPE_MENU)
+		ev->u.ctrl.step = 1;
+	else
+		ev->u.ctrl.step = ctrl->step;
+	ev->u.ctrl.default_value = ctrl->default_value;
+}
+
+static void send_event(struct v4l2_fh *fh, struct v4l2_ctrl *ctrl, u32 changes)
+{
+	struct v4l2_event ev;
+	struct v4l2_ctrl_fh *pos;
+
+	if (list_empty(&ctrl->fhs))
+			return;
+	fill_event(&ev, ctrl, changes);
+
+	list_for_each_entry(pos, &ctrl->fhs, node)
+		if (pos->fh != fh)
+			v4l2_event_queue_fh(pos->fh, &ev);
+}
+
 /* Helper function: copy the current control value back to the caller */
 static int cur_to_user(struct v4l2_ext_control *c,
 		       struct v4l2_ctrl *ctrl)
@@ -660,17 +696,25 @@ static int ctrl_is_volatile(struct v4l2_ext_control *c,
 static void new_to_cur(struct v4l2_fh *fh, struct v4l2_ctrl *ctrl,
 						bool update_inactive)
 {
+	bool changed = false;
+
 	if (ctrl == NULL)
 		return;
 	switch (ctrl->type) {
+	case V4L2_CTRL_TYPE_BUTTON:
+		changed = true;
+		break;
 	case V4L2_CTRL_TYPE_STRING:
 		/* strings are always 0-terminated */
+		changed = strcmp(ctrl->string, ctrl->cur.string);
 		strcpy(ctrl->cur.string, ctrl->string);
 		break;
 	case V4L2_CTRL_TYPE_INTEGER64:
+		changed = ctrl->val64 != ctrl->cur.val64;
 		ctrl->cur.val64 = ctrl->val64;
 		break;
 	default:
+		changed = ctrl->val != ctrl->cur.val;
 		ctrl->cur.val = ctrl->val;
 		break;
 	}
@@ -679,6 +723,10 @@ static void new_to_cur(struct v4l2_fh *fh, struct v4l2_ctrl *ctrl,
 		if (!is_cur_manual(ctrl->cluster[0]))
 			ctrl->flags |= V4L2_CTRL_FLAG_INACTIVE;
 	}
+	if (changed || update_inactive)
+		send_event(fh, ctrl,
+			(changed ? V4L2_EVENT_CTRL_CH_VALUE : 0) |
+			(update_inactive ? V4L2_EVENT_CTRL_CH_FLAGS : 0));
 }
 
 /* Copy the current value to the new value */
@@ -819,6 +867,7 @@ void v4l2_ctrl_handler_free(struct v4l2_ctrl_handler *hdl)
 {
 	struct v4l2_ctrl_ref *ref, *next_ref;
 	struct v4l2_ctrl *ctrl, *next_ctrl;
+	struct v4l2_ctrl_fh *ctrl_fh, *next_ctrl_fh;
 
 	if (hdl == NULL || hdl->buckets == NULL)
 		return;
@@ -832,6 +881,10 @@ void v4l2_ctrl_handler_free(struct v4l2_ctrl_handler *hdl)
 	/* Free all controls owned by the handler */
 	list_for_each_entry_safe(ctrl, next_ctrl, &hdl->ctrls, node) {
 		list_del(&ctrl->node);
+		list_for_each_entry_safe(ctrl_fh, next_ctrl_fh, &ctrl->fhs, node) {
+			list_del(&ctrl_fh->node);
+			kfree(ctrl_fh);
+		}
 		kfree(ctrl);
 	}
 	kfree(hdl->buckets);
@@ -1030,6 +1083,7 @@ static struct v4l2_ctrl *v4l2_ctrl_new(struct v4l2_ctrl_handler *hdl,
 	}
 
 	INIT_LIST_HEAD(&ctrl->node);
+	INIT_LIST_HEAD(&ctrl->fhs);
 	ctrl->handler = hdl;
 	ctrl->ops = ops;
 	ctrl->id = id;
@@ -1171,6 +1225,9 @@ int v4l2_ctrl_add_handler(struct v4l2_ctrl_handler *hdl,
 		/* Skip handler-private controls. */
 		if (ctrl->is_private)
 			continue;
+		/* And control classes */
+		if (ctrl->type == V4L2_CTRL_TYPE_CTRL_CLASS)
+			continue;
 		ret = handler_new_ref(hdl, ctrl);
 		if (ret)
 			break;
@@ -1222,15 +1279,21 @@ EXPORT_SYMBOL(v4l2_ctrl_auto_cluster);
 /* Activate/deactivate a control. */
 void v4l2_ctrl_activate(struct v4l2_ctrl *ctrl, bool active)
 {
+	/* invert since the actual flag is called 'inactive' */
+	bool inactive = !active;
+	bool old;
+
 	if (ctrl == NULL)
 		return;
 
-	if (!active)
+	if (inactive)
 		/* set V4L2_CTRL_FLAG_INACTIVE */
-		set_bit(4, &ctrl->flags);
+		old = test_and_set_bit(4, &ctrl->flags);
 	else
 		/* clear V4L2_CTRL_FLAG_INACTIVE */
-		clear_bit(4, &ctrl->flags);
+		old = test_and_clear_bit(4, &ctrl->flags);
+	if (old != inactive)
+		send_event(NULL, ctrl, V4L2_EVENT_CTRL_CH_FLAGS);
 }
 EXPORT_SYMBOL(v4l2_ctrl_activate);
 
@@ -1242,15 +1305,21 @@ EXPORT_SYMBOL(v4l2_ctrl_activate);
    these controls. */
 void v4l2_ctrl_grab(struct v4l2_ctrl *ctrl, bool grabbed)
 {
+	bool old;
+
 	if (ctrl == NULL)
 		return;
 
+	v4l2_ctrl_lock(ctrl);
 	if (grabbed)
 		/* set V4L2_CTRL_FLAG_GRABBED */
-		set_bit(1, &ctrl->flags);
+		old = test_and_set_bit(1, &ctrl->flags);
 	else
 		/* clear V4L2_CTRL_FLAG_GRABBED */
-		clear_bit(1, &ctrl->flags);
+		old = test_and_clear_bit(1, &ctrl->flags);
+	if (old != grabbed)
+		send_event(NULL, ctrl, V4L2_EVENT_CTRL_CH_FLAGS);
+	v4l2_ctrl_unlock(ctrl);
 }
 EXPORT_SYMBOL(v4l2_ctrl_grab);
 
@@ -1956,3 +2025,39 @@ int v4l2_ctrl_s_ctrl(struct v4l2_ctrl *ctrl, s32 val)
 	return set_ctrl(NULL, ctrl, &val);
 }
 EXPORT_SYMBOL(v4l2_ctrl_s_ctrl);
+
+void v4l2_ctrl_add_fh(struct v4l2_ctrl_handler *hdl,
+		struct v4l2_ctrl_fh *ctrl_fh,
+		struct v4l2_event_subscription *sub)
+{
+	struct v4l2_ctrl *ctrl = v4l2_ctrl_find(hdl, sub->id);
+
+	v4l2_ctrl_lock(ctrl);
+	list_add_tail(&ctrl_fh->node, &ctrl->fhs);
+	if (ctrl->type != V4L2_CTRL_TYPE_CTRL_CLASS &&
+	    (sub->flags & V4L2_EVENT_SUB_FL_SEND_INITIAL)) {
+		struct v4l2_event ev;
+
+		fill_event(&ev, ctrl, V4L2_EVENT_CTRL_CH_VALUE |
+			V4L2_EVENT_CTRL_CH_FLAGS);
+		v4l2_event_queue_fh(ctrl_fh->fh, &ev);
+	}
+	v4l2_ctrl_unlock(ctrl);
+}
+EXPORT_SYMBOL(v4l2_ctrl_add_fh);
+
+void v4l2_ctrl_del_fh(struct v4l2_ctrl *ctrl, struct v4l2_fh *fh)
+{
+	struct v4l2_ctrl_fh *pos;
+
+	v4l2_ctrl_lock(ctrl);
+	list_for_each_entry(pos, &ctrl->fhs, node) {
+		if (pos->fh == fh) {
+			list_del(&pos->node);
+			kfree(pos);
+			break;
+		}
+	}
+	v4l2_ctrl_unlock(ctrl);
+}
+EXPORT_SYMBOL(v4l2_ctrl_del_fh);
diff --git a/drivers/media/video/v4l2-event.c b/drivers/media/video/v4l2-event.c
index 69fd343d477..670f2f834e6 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);
 
diff --git a/drivers/media/video/v4l2-fh.c b/drivers/media/video/v4l2-fh.c
index 863501194d0..c6aef84099a 100644
--- a/drivers/media/video/v4l2-fh.c
+++ b/drivers/media/video/v4l2-fh.c
@@ -93,10 +93,8 @@ void v4l2_fh_exit(struct v4l2_fh *fh)
 {
 	if (fh->vdev == NULL)
 		return;
-
-	fh->vdev = NULL;
-
 	v4l2_event_free(fh);
+	fh->vdev = NULL;
 }
 EXPORT_SYMBOL_GPL(v4l2_fh_exit);