[PATCH 1/5] of: introduce of_graph_get_remote_node

[Rob Herring <robh@kernel.org>]

The OF graph API leaves too much of the graph walking to clients when
in many cases the driver doesn't care about accessing the port or
endpoint nodes. The drivers typically just want the device connected via
a particular graph connection. of_graph_get_remote_node provides this
functionality.

Signed-off-by: Rob Herring <robh@kernel.org>
---
 drivers/of/base.c        | 28 ++++++++++++++++++++++++++++
 include/linux/of_graph.h |  8 ++++++++
 2 files changed, 36 insertions(+)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index d4bea3c797d6..ea18ab16b92c 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -2469,3 +2469,31 @@ struct device_node *of_graph_get_remote_port(const struct device_node *node)
 	return of_get_next_parent(np);
 }
 EXPORT_SYMBOL(of_graph_get_remote_port);
+
+struct device_node *of_graph_get_remote_node(const struct device_node *node,
+					     int port, int endpoint)
+{
+	struct device_node *endpoint_node, *remote;
+
+	endpoint_node = of_graph_get_endpoint_by_regs(node, port, endpoint);
+	if (!endpoint_node) {
+		pr_debug("no valid endpoint (%d, %d) for node %s\n",
+			 port, endpoint, node->full_name);
+		return NULL;
+	}
+
+	remote = of_graph_get_remote_port_parent(endpoint_node);
+	of_node_put(endpoint);
+	if (!remote) {
+		pr_debug("no valid remote node\n");
+		return NULL;
+	}
+
+	if (!of_device_is_available(remote)) {
+		pr_debug("not available for remote node\n");
+		return NULL;
+	}
+
+	return remote;
+}
+EXPORT_SYMBOL(of_graph_get_remote_node);
diff --git a/include/linux/of_graph.h b/include/linux/of_graph.h
index bb3a5a2cd570..7b71d3e09209 100644
--- a/include/linux/of_graph.h
+++ b/include/linux/of_graph.h
@@ -51,6 +51,8 @@ struct device_node *of_graph_get_endpoint_by_regs(
 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);
+struct device_node *of_graph_get_remote_node(const struct device_node *node,
+					     int port, int endpoint);
 #else
 
 static inline int of_graph_parse_endpoint(const struct device_node *node,
@@ -89,6 +91,12 @@ static inline struct device_node *of_graph_get_remote_port(
 {
 	return NULL;
 }
+static inline struct device_node *of_graph_get_remote_node(
+					const struct device_node *node,
+					int port, int endpoint)
+{
+	return NULL;
+}
 
 #endif /* CONFIG_OF */
 
-- 
2.10.1