In some cases it's very useful to silently check whether port node exists
at all in a device-tree before proceeding with parsing the graph. The DRM
bridges code is one example of such case where absence of a graph in a
device-tree is a legit condition.
This patch adds of_graph_is_present() which returns true if given
device-tree node contains OF graph port.
Reviewed-by: Rob Herring <robh@xxxxxxxxxx>
Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
---
drivers/of/property.c | 23 +++++++++++++++++++++++
include/linux/of_graph.h | 6 ++++++
2 files changed, 29 insertions(+)
diff --git a/drivers/of/property.c b/drivers/of/property.c
index 6a5760f0d6cd..fed7229d9d9f 100644
--- a/drivers/of/property.c
+++ b/drivers/of/property.c
@@ -29,6 +29,29 @@
#include "of_private.h"
+/**
+ * of_graph_is_present() - check graph's presence
+ * @node: pointer to device_node containing graph port
+ *
+ * Return: True if @node has a port or ports (with a port) sub-node,
+ * false otherwise.
+ */
+bool of_graph_is_present(const struct device_node *node)
+{
+ struct device_node *ports, *port;
+
+ ports = of_get_child_by_name(node, "ports");
+ if (ports)
+ node = ports;
+
+ port = of_get_child_by_name(node, "port");
+ of_node_put(ports);
+ of_node_put(port);
+
+ return !!port;
+}
+EXPORT_SYMBOL(of_graph_is_present);
+
/**
* of_property_count_elems_of_size - Count the number of elements in a property
*
diff --git a/include/linux/of_graph.h b/include/linux/of_graph.h
index 01038a6aade0..4d7756087b6b 100644
--- a/include/linux/of_graph.h
+++ b/include/linux/of_graph.h
@@ -38,6 +38,7 @@ struct of_endpoint {
child = of_graph_get_next_endpoint(parent, child))
#ifdef CONFIG_OF
+bool of_graph_is_present(const struct device_node *node);
int of_graph_parse_endpoint(const struct device_node *node,
struct of_endpoint *endpoint);
int of_graph_get_endpoint_count(const struct device_node *np);
@@ -56,6 +57,11 @@ struct device_node *of_graph_get_remote_node(const struct device_node *node,
u32 port, u32 endpoint);
#else
+static inline bool of_graph_is_present(const struct device_node *node)
+{
+ return false;
+}
+
static inline int of_graph_parse_endpoint(const struct device_node *node,
struct of_endpoint *endpoint)
{
--
2.26.0
