of: property: add of_graph_get_next_port()

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 each endpoints

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

In above case, it finds endpoint as (1) -> (2) -> ...

Basically, user/driver knows which port is used for what, but not in
all cases. For example on flexible/generic driver case, how many ports
are used is not fixed.

For example Sound Generic Card driver which is very flexible/generic and
used from many venders can't know how many ports are used, and used for
what, because it depends on each vender SoC and/or its used board.

And more, the port can have multi endpoints. For example Generic Sound
Card case, it supports many type of connection between CPU / Codec, and
some of them uses multi endpoint in one port. see below.

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

Generic Sound Card want to handle each connection via "port" base instead
of "endpoint" base. But, it is very difficult to handle each "port" via
existing for_each_endpoint_of_node(). Because getting each "port" via
of_get_parent() from each "endpoint" doesn't work. For example in above
case, both (1) (2) endpoint has same "port" (= A).

Add "port" base functions.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/87ldyeb5t9.wl-kuninori.morimoto.gx@renesas.com
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>

1 files changed, 54 insertions, 0 deletions

diff --git a/drivers/of/property.c b/drivers/of/property.c
index 33dd72cad4ab..6dd5461ea359 100644
--- a/drivers/of/property.c
+++ b/drivers/of/property.c
@@ -631,6 +631,43 @@ struct device_node *of_graph_get_port_by_id(struct device_node *parent, u32 id)
 EXPORT_SYMBOL(of_graph_get_port_by_id);
 
 /**
+ * of_graph_get_next_port() - get next port node.
+ * @parent: pointer to the parent device node, or parent ports node
+ * @prev: previous port node, or NULL to get first
+ *
+ * Parent device node can be used as @parent whether device node has ports node
+ * or not. It will work same as ports@0 node.
+ *
+ * Return: A '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)
+{
+	if (!parent)
+		return NULL;
+
+	if (!prev) {
+		struct device_node *node __free(device_node) =
+			of_get_child_by_name(parent, "ports");
+
+		if (node)
+			parent = node;
+
+		return of_get_child_by_name(parent, "port");
+	}
+
+	do {
+		prev = of_get_next_child(parent, prev);
+		if (!prev)
+			break;
+	} while (!of_node_name_eq(prev, "port"));
+
+	return prev;
+}
+EXPORT_SYMBOL(of_graph_get_next_port);
+
+/**
  * of_graph_get_next_endpoint() - get next endpoint node
  * @parent: pointer to the parent device node
  * @prev: previous endpoint node, or NULL to get first
@@ -824,6 +861,23 @@ unsigned int of_graph_get_endpoint_count(const struct device_node *np)
 EXPORT_SYMBOL(of_graph_get_endpoint_count);
 
 /**
+ * of_graph_get_port_count() - get the number of port in a device or ports node
+ * @np: pointer to the device or ports node
+ *
+ * Return: count of port of this device or ports node
+ */
+unsigned int of_graph_get_port_count(struct device_node *np)
+{
+	unsigned int num = 0;
+
+	for_each_of_graph_port(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
  * @port: identifier (value of reg property) of the parent port node