[PATCH 1/2] of: Add helper to lookup non port child node

[Jagan Teki <jagan@amarulasolutions.com>]

Add of_get_non_port_child() helper that can be used to lookup
non port child nodes.

Some OF graphs don't require 'ports' to represent the next output
instead, it simply adds a child node on a given parent node. This
helper lookup that child node, however that child node is not a
'port' on given parent as 'port' based nodes are looked up via
of_graph_get_remote_node().

Example OF graph representation of DSI host, which doesn't
have 'ports'.

dsi {
	#address-cells = <1>;
	#size-cells = <0>;

	port {
		dsi_in_tcon0: endpoint {
			remote-endpoint = <tcon0_out_dsi>;
	};

	panel@0 {
		reg = <0>;
	};
};

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
---
 drivers/of/base.c  | 29 +++++++++++++++++++++++++++++
 include/linux/of.h |  6 ++++++
 2 files changed, 35 insertions(+)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index 61de453b885c..31bbf885b0f8 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -854,6 +854,35 @@ struct device_node *of_get_compatible_child(const struct device_node *parent,
 }
 EXPORT_SYMBOL(of_get_compatible_child);
 
+/**
+ * of_get_non_port_child - Find the non port child node for a given parent
+ * @node:	parent node
+ *
+ * This function looks for child node which is not port child for given parent.
+ *
+ * Return: A node pointer if found, with refcount incremented, use
+ * of_node_put() on it when done.
+ * Returns NULL if node is not found.
+ */
+struct device_node *of_get_non_port_child(const struct device_node *parent)
+{
+	struct device_node *child;
+
+	for_each_child_of_node(parent, child) {
+		if (of_node_name_eq(child, "port"))
+			continue;
+
+		if (!of_device_is_available(child)) {
+			of_node_put(child);
+			continue;
+		}
+		break;
+	}
+
+	return child;
+}
+EXPORT_SYMBOL(of_get_non_port_child);
+
 /**
  * of_get_child_by_name - Find the child node by name for a given parent
  * @node:	parent node
diff --git a/include/linux/of.h b/include/linux/of.h
index ff143a027abc..3e699becef82 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -290,6 +290,7 @@ extern struct device_node *of_get_next_child(const struct device_node *node,
 extern struct device_node *of_get_next_available_child(
 	const struct device_node *node, struct device_node *prev);
 
+extern struct device_node *of_get_non_port_child(const struct device_node *parent);
 extern struct device_node *of_get_compatible_child(const struct device_node *parent,
 					const char *compatible);
 extern struct device_node *of_get_child_by_name(const struct device_node *node,
@@ -678,6 +679,11 @@ static inline bool of_have_populated_dt(void)
 	return false;
 }
 
+static inline struct device_node *of_get_non_port_child(const struct device_node *parent)
+{
+	return NULL;
+}
+
 static inline struct device_node *of_get_compatible_child(const struct device_node *parent,
 					const char *compatible)
 {
-- 
2.25.1