core: ofnode: add ofnode_get_parent function

The Rockchip video drivers need to walk the ofnode-parrents to find
an enclosing device that has a UCLASS_DISPLAY driver bound.  This
adds a ofnode_get_parent()-function that returns the parent-node.

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Tested-by: Klaus Goger <klaus.goger@theobroma-systems.com>
Reviewed-by: Anatolij Gustschin <agust@denx.de>

drivers/core/ofnode.c

@@ -165,6 +165,20 @@ ofnode ofnode_next_subnode(ofnode node)
 		fdt_next_subnode(gd->fdt_blob, ofnode_to_offset(node)));
 }
 
+ofnode ofnode_get_parent(ofnode node)
+{
+	ofnode parent;
+
+	assert(ofnode_valid(node));
+	if (ofnode_is_np(node))
+		parent = np_to_ofnode(of_get_parent(ofnode_to_np(node)));
+	else
+		parent.of_offset = fdt_parent_offset(gd->fdt_blob,
+						     ofnode_to_offset(node));
+
+	return parent;
+}
+
 const char *ofnode_get_name(ofnode node)
 {
 	assert(ofnode_valid(node));

include/dm/ofnode.h

@@ -301,6 +301,14 @@ ofnode ofnode_first_subnode(ofnode node);
  */
 ofnode ofnode_next_subnode(ofnode node);
 
+/**
+ * ofnode_get_parent() - get the ofnode's parent (enclosing ofnode)
+ *
+ * @node: valid node to look up
+ * @return ofnode reference of the parent node
+ */
+ofnode ofnode_get_parent(ofnode node);
+
 /**
  * ofnode_get_name() - get the name of a node
  *