Date:   Wed, 13 Jan 2021 15:46:03 +0900
From:   Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
To:     Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>
Cc:     devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] of: property: add port base loop


From: Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>

We have endpoint base functions
	- of_graph_get_next_endpoint()
	- of_graph_get_endpoint_count()
	- for_each_endpoint_of_node()

Here, for_each_endpoint_of_node() loop finds endpoint

	ports {
		port@0 {
(1)			endpoint {...};
		};
		port@1 {
(2)			endpoint {...};
		};
		...
	};

In above case, for_each_endpoint_of_node() loop
finds endpoint as (1) -> (2) -> ...
We can check endpoint parent to get its port
if user want to do something to it.

But port can have multi endpoints.
In such case, it is difficult to find
port@0 -> port@1 -> ...

	ports {
		port@0 {
(1)			endpoint@0 {...};
(2)			endpoint@1 {...};
		};
		port@1 {
(3)			endpoint {...};
		};
		...
	};

In such case, people want to have port base loop
instead of endpoints base loop.
This patch adds such functions/macros.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
---
 drivers/of/property.c    | 69 ++++++++++++++++++++++++++++++++++------
 include/linux/of_graph.h | 14 ++++++++
 2 files changed, 73 insertions(+), 10 deletions(-)

diff --git a/drivers/of/property.c b/drivers/of/property.c
index 5f9eed79a8aa..9b511cfe97b3 100644
--- a/drivers/of/property.c
+++ b/drivers/of/property.c
@@ -631,15 +631,7 @@ struct device_node *of_graph_get_next_endpoint(const struct device_node *parent,
 	 * parent port node.
 	 */
 	if (!prev) {
-		struct device_node *node;
-
-		node = of_get_child_by_name(parent, "ports");
-		if (node)
-			parent = node;
-
-		port = of_get_child_by_name(parent, "port");
-		of_node_put(node);
-
+		port = of_graph_get_next_port(parent, NULL);
 		if (!port) {
 			pr_err("graph: no port node found in %pOF\n", parent);
 			return NULL;
@@ -666,14 +658,59 @@ struct device_node *of_graph_get_next_endpoint(const struct device_node *parent,
 		/* No more endpoints under this port, try the next one. */
 		prev = NULL;
 
+		port = of_graph_get_next_port(parent, port);
+		if (!port)
+			return NULL;
+	}
+}
+EXPORT_SYMBOL(of_graph_get_next_endpoint);
+
+/**
+ * of_graph_get_next_port() - get next port node
+ * @parent: pointer to the parent device node
+ * @prev: previous port node, or NULL to get first
+ *
+ * Return: An 'port' node pointer with refcount incremented. Refcount
+ * of the passed @prev node is decremented.
+ */
+struct device_node *of_graph_get_next_port(const struct device_node *parent,
+					   struct device_node *prev)
+{
+	struct device_node *port = prev;
+
+	if (!parent)
+		return NULL;
+
+	/*
+	 * Start by locating the port node. If no previous endpoint is specified
+	 * search for the first port node, otherwise get the previous endpoint
+	 * parent port node.
+	 */
+	if (!port) {
+		struct device_node *node;
+
+		node = of_get_child_by_name(parent, "ports");
+		if (node)
+			parent = node;
+
+		port = of_get_child_by_name(parent, "port");
+		of_node_put(node);
+
+		if (!port) {
+			pr_err("graph: no port node found in %pOF\n", parent);
+			return NULL;
+		}
+	} else {
 		do {
 			port = of_get_next_child(parent, port);
 			if (!port)
 				return NULL;
 		} while (!of_node_name_eq(port, "port"));
 	}
+
+	return port;
 }
-EXPORT_SYMBOL(of_graph_get_next_endpoint);
+EXPORT_SYMBOL(of_graph_get_next_port);
 
 /**
  * of_graph_get_endpoint_by_regs() - get endpoint node of specific identifiers
@@ -800,6 +837,18 @@ int of_graph_get_endpoint_count(const struct device_node *np)
 }
 EXPORT_SYMBOL(of_graph_get_endpoint_count);
 
+int of_graph_get_port_count(const struct device_node *np)
+{
+	struct device_node *port;
+	int num = 0;
+
+	for_each_port_of_node(np, port)
+		num++;
+
+	return num;
+}
+EXPORT_SYMBOL(of_graph_get_port_count);
+
 /**
  * of_graph_get_remote_node() - get remote parent device_node for given port/endpoint
  * @node: pointer to parent device_node containing graph port/endpoint
diff --git a/include/linux/of_graph.h b/include/linux/of_graph.h
index 4d7756087b6b..8cd3bd674ebd 100644
--- a/include/linux/of_graph.h
+++ b/include/linux/of_graph.h
@@ -26,6 +26,17 @@ struct of_endpoint {
 	const struct device_node *local_node;
 };
 
+/**
+ * for_each_port_of_node - iterate over every port in a device node
+ * @parent: parent device node containing ports and port
+ * @child: loop variable pointing to the current port node
+ *
+ * When breaking out of the loop, of_node_put(child) has to be called manually.
+ */
+#define for_each_port_of_node(parent, child)			\
+	for (child = of_graph_get_next_port(parent, NULL); child != NULL; \
+	     child = of_graph_get_next_port(parent, child))
+
 /**
  * for_each_endpoint_of_node - iterate over every endpoint in a device node
  * @parent: parent device node containing ports and endpoints
@@ -41,8 +52,11 @@ struct of_endpoint {
 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_port_count(const struct device_node *np);
 int of_graph_get_endpoint_count(const struct device_node *np);
 struct device_node *of_graph_get_port_by_id(struct device_node *node, u32 id);
+struct device_node *of_graph_get_next_port(const struct device_node *parent,
+					   struct device_node *previous);
 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(
-- 
2.25.1

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