media: subdev: Add for_each_active_route() macro

JIRA: https://issues.redhat.com/browse/RHEL-67885

commit 837f92f070f6b7e877143eb168025995688b9756
Author: Jacopo Mondi <jacopo+renesas@jmondi.org>
Date: Sun, 17 Oct 2021 20:24:42 +0200

  Add a for_each_active_route() macro to replace the repeated pattern
  of iterating on the active routes of a routing table.

  Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
  Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
  Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

Signed-off-by: Kate Hsuan <hpa@redhat.com>

.clang-format

@@ -140,6 +140,7 @@ ForEachMacros:
   - 'for_each_active_dev_scope'
   - 'for_each_active_drhd_unit'
   - 'for_each_active_iommu'
+  - 'for_each_active_route'
   - 'for_each_aggr_pgid'
   - 'for_each_available_child_of_node'
   - 'for_each_bio'

drivers/media/v4l2-core/v4l2-subdev.c

@@ -1239,6 +1239,26 @@ int v4l2_subdev_set_routing(struct v4l2_subdev *sd,
 }
 EXPORT_SYMBOL_GPL(v4l2_subdev_set_routing);
 
+struct v4l2_subdev_route *
+__v4l2_subdev_next_active_route(const struct v4l2_subdev_krouting *routing,
+				struct v4l2_subdev_route *route)
+{
+	if (route)
+		++route;
+	else
+		route = &routing->routes[0];
+
+	for (; route < routing->routes + routing->num_routes; ++route) {
+		if (!(route->flags & V4L2_SUBDEV_ROUTE_FL_ACTIVE))
+			continue;
+
+		return route;
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(__v4l2_subdev_next_active_route);
+
 #endif /* CONFIG_VIDEO_V4L2_SUBDEV_API */
 
 #endif /* CONFIG_MEDIA_CONTROLLER */

include/media/v4l2-subdev.h

@@ -1440,6 +1440,19 @@ int v4l2_subdev_set_routing(struct v4l2_subdev *sd,
 			    struct v4l2_subdev_state *state,
 			    const struct v4l2_subdev_krouting *routing);
 
+struct v4l2_subdev_route *
+__v4l2_subdev_next_active_route(const struct v4l2_subdev_krouting *routing,
+				struct v4l2_subdev_route *route);
+
+/**
+ * for_each_active_route - iterate on all active routes of a routing table
+ * @routing: The routing table
+ * @route: The route iterator
+ */
+#define for_each_active_route(routing, route) \
+	for ((route) = NULL;                  \
+	     ((route) = __v4l2_subdev_next_active_route((routing), (route)));)
+
 #endif /* CONFIG_VIDEO_V4L2_SUBDEV_API */
 
 #endif /* CONFIG_MEDIA_CONTROLLER */