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, 28 insertions, 0 deletions

diff --git a/include/linux/of_graph.h b/include/linux/of_graph.h
index a4bea62bfa29..44518f3583a4 100644
--- a/include/linux/of_graph.h
+++ b/include/linux/of_graph.h
@@ -11,6 +11,7 @@
 #ifndef __LINUX_OF_GRAPH_H
 #define __LINUX_OF_GRAPH_H
 
+#include <linux/cleanup.h>
 #include <linux/types.h>
 #include <linux/errno.h>
 
@@ -37,14 +38,29 @@ struct of_endpoint {
 	for (child = of_graph_get_next_endpoint(parent, NULL); child != NULL; \
 	     child = of_graph_get_next_endpoint(parent, child))
 
+/**
+ * for_each_of_graph_port - iterate over every port in a device or ports node
+ * @parent: parent device or ports node containing port
+ * @child: loop variable pointing to the current port node
+ *
+ * When breaking out of the loop, and continue to use the @child, you need to
+ * use return_ptr(@child) or no_free_ptr(@child) not to call __free() for it.
+ */
+#define for_each_of_graph_port(parent, child)			\
+	for (struct device_node *child __free(device_node) = of_graph_get_next_port(parent, NULL);\
+	     child != NULL; child = of_graph_get_next_port(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);
 unsigned int of_graph_get_endpoint_count(const struct device_node *np);
+unsigned int of_graph_get_port_count(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_endpoint(const struct device_node *parent,
 					struct device_node *previous);
+struct device_node *of_graph_get_next_port(const struct device_node *parent,
+					   struct device_node *port);
 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_endpoint(
@@ -73,6 +89,11 @@ static inline unsigned int of_graph_get_endpoint_count(const struct device_node
 	return 0;
 }
 
+static inline unsigned int of_graph_get_port_count(struct device_node *np)
+{
+	return 0;
+}
+
 static inline struct device_node *of_graph_get_port_by_id(
 					struct device_node *node, u32 id)
 {
@@ -86,6 +107,13 @@ static inline struct device_node *of_graph_get_next_endpoint(
 	return NULL;
 }
 
+static inline struct device_node *of_graph_get_next_port(
+					const struct device_node *parent,
+					struct device_node *previous)
+{
+	return NULL;
+}
+
 static inline struct device_node *of_graph_get_endpoint_by_regs(
 		const struct device_node *parent, int port_reg, int reg)
 {