[media] of: move graph helpers from drivers/media/v4l2-core to drivers/of

This patch moves the parsing helpers used to parse connected graphs
in the device tree, like the video interface bindings documented in
Documentation/devicetree/bindings/media/video-interfaces.txt, from
drivers/media/v4l2-core/v4l2-of.c into drivers/of/base.c.

This allows to reuse the same parser code from outside the V4L2
framework, most importantly from display drivers.
The functions v4l2_of_get_next_endpoint, v4l2_of_get_remote_port,
and v4l2_of_get_remote_port_parent are moved. They are renamed to
of_graph_get_next_endpoint, of_graph_get_remote_port, and
of_graph_get_remote_port_parent, respectively.
Since there are not that many current users yet, switch all of
them to the new functions right away.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Acked-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
Acked-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
diff --git a/include/linux/of_graph.h b/include/linux/of_graph.h
new file mode 100644
index 0000000..3bbeb60
--- /dev/null
+++ b/include/linux/of_graph.h
@@ -0,0 +1,46 @@
+/*
+ * OF graph binding parsing helpers
+ *
+ * Copyright (C) 2012 - 2013 Samsung Electronics Co., Ltd.
+ * Author: Sylwester Nawrocki <s.nawrocki@samsung.com>
+ *
+ * Copyright (C) 2012 Renesas Electronics Corp.
+ * Author: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ */
+#ifndef __LINUX_OF_GRAPH_H
+#define __LINUX_OF_GRAPH_H
+
+#ifdef CONFIG_OF
+struct device_node *of_graph_get_next_endpoint(const struct device_node *parent,
+					struct device_node *previous);
+struct device_node *of_graph_get_remote_port_parent(
+					const struct device_node *node);
+struct device_node *of_graph_get_remote_port(const struct device_node *node);
+#else
+
+static inline struct device_node *of_graph_get_next_endpoint(
+					const struct device_node *parent,
+					struct device_node *previous)
+{
+	return NULL;
+}
+
+static inline struct device_node *of_graph_get_remote_port_parent(
+					const struct device_node *node)
+{
+	return NULL;
+}
+
+static inline struct device_node *of_graph_get_remote_port(
+					const struct device_node *node)
+{
+	return NULL;
+}
+
+#endif /* CONFIG_OF */
+
+#endif /* __LINUX_OF_GRAPH_H */