[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>

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);