[PATCH v6 06/15] of: add helper for getting endpoint node of specific identifiers

[Hyungwon Hwang]

When there are multiple ports or multiple endpoints in a port, they have to be
distinguished by the value of reg property. It is common. The drivers can get
the specific endpoint in the specific port via this function. Now the drivers
have to implement this code in themselves or have to force the order of dt nodes
to get the right node.

Signed-off-by: Hyungwon Hwang <human.hwang at samsung.com>
Acked-by: Rob Herring <robh+dt at kernel.org>
---
Changes before:
- Refer https://patchwork.kernel.org/patch/6191751/
Changes for v6:
- None
 drivers/of/base.c        | 33 +++++++++++++++++++++++++++++++++
 include/linux/of_graph.h |  8 ++++++++
 2 files changed, 41 insertions(+)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index 99764db..f3b583b 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -2233,6 +2233,39 @@ struct device_node *of_graph_get_next_endpoint(const struct device_node *parent,
 EXPORT_SYMBOL(of_graph_get_next_endpoint);

 /**
+ * of_graph_get_endpoint_by_regs() - get endpoint node of specific identifiers
+ * @parent: pointer to the parent device node
+ * @port_reg: identifier (value of reg property) of the parent port node
+ * @reg: identifier (value of reg property) of the endpoint node
+ *
+ * Return: An 'endpoint' node pointer which is identified by reg and at the same
+ * is the child of a port node identified by port_reg. reg and port_reg are
+ * ignored when they are -1.
+ */
+struct device_node *of_graph_get_endpoint_by_regs(
+	const struct device_node *parent, int port_reg, int reg)
+{
+	struct of_endpoint endpoint;
+	struct device_node *node, *prev_node = NULL;
+
+	while (1) {
+		node = of_graph_get_next_endpoint(parent, prev_node);
+		of_node_put(prev_node);
+		if (!node)
+			break;
+
+		of_graph_parse_endpoint(node, &endpoint);
+		if (((port_reg == -1) || (endpoint.port == port_reg)) &&
+			((reg == -1) || (endpoint.id == reg)))
+			return node;
+
+		prev_node = node;
+	}
+
+	return NULL;
+}
+
+/**
  * of_graph_get_remote_port_parent() - get remote port's parent node
  * @node: pointer to a local endpoint device_node
  *
diff --git a/include/linux/of_graph.h b/include/linux/of_graph.h
index 7bc92e0..1c1d5b9 100644
--- a/include/linux/of_graph.h
+++ b/include/linux/of_graph.h
@@ -45,6 +45,8 @@ int of_graph_parse_endpoint(const struct device_node *node,
 struct device_node *of_graph_get_port_by_id(struct device_node *node, u32 id);
 struct device_node *of_graph_get_next_endpoint(const struct device_node *parent,
 					struct device_node *previous);
+struct device_node *of_graph_get_endpoint_by_regs(
+		const struct device_node *parent, int port_reg, int reg);
 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);
@@ -69,6 +71,12 @@ static inline struct device_node *of_graph_get_next_endpoint(
 	return NULL;
 }

+struct device_node *of_graph_get_endpoint_by_regs(
+		const struct device_node *parent, int port_reg, int reg)
+{
+	return NULL;
+}
+
 static inline struct device_node *of_graph_get_remote_port_parent(
 					const struct device_node *node)
 {
--
1.9.1