[PATCH v6 0/3] Add of-graph helpers to loop over endpoints and find ports by id

@@ -52,15 +52,6 @@ of_coresight_get_endpoint_device(struct device_node *endpoint)
 			       endpoint, of_dev_node_match);
 }
 
-static struct device_node *of_get_coresight_endpoint(
-		const struct device_node *parent, struct device_node *prev)
-{
-	struct device_node *node = of_graph_get_next_endpoint(parent, prev);
-
-	of_node_put(prev);
-	return node;
-}
-
 static void of_coresight_get_ports(struct device_node *node,
 				   int *nr_inport, int *nr_outport)
 {

@@ -68,7 +59,7 @@ static void of_coresight_get_ports(struct device_node *node,
 	int in = 0, out = 0;
 
 	do {
-		ep = of_get_coresight_endpoint(node, ep);
+		ep = of_graph_get_next_endpoint(node, ep);
 		if (!ep)
 			break;
 

@@ -140,7 +131,7 @@ struct coresight_platform_data *of_get_coresight_platform_data(
 		/* Iterate through each port to discover topology */
 		do {
 			/* Get a handle on a port */
-			ep = of_get_coresight_endpoint(node, ep);
+			ep = of_graph_get_next_endpoint(node, ep);
 			if (!ep)
 				break;
 

@@ -436,15 +436,6 @@ static uint32_t imx_drm_find_crtc_mask(struct imx_drm_device *imxdrm,
 	return 0;
 }
 
-static struct device_node *imx_drm_of_get_next_endpoint(
-		const struct device_node *parent, struct device_node *prev)
-{
-	struct device_node *node = of_graph_get_next_endpoint(parent, prev);
-
-	of_node_put(prev);
-	return node;
-}
-
 int imx_drm_encoder_parse_of(struct drm_device *drm,
 	struct drm_encoder *encoder, struct device_node *np)
 {

@@ -456,7 +447,7 @@ int imx_drm_encoder_parse_of(struct drm_device *drm,
 	for (i = 0; ; i++) {
 		u32 mask;
 
-		ep = imx_drm_of_get_next_endpoint(np, ep);
+		ep = of_graph_get_next_endpoint(np, ep);
 		if (!ep)
 			break;
 

@@ -504,7 +495,7 @@ int imx_drm_encoder_get_mux_id(struct device_node *node,
 		return -EINVAL;
 
 	do {
-		ep = imx_drm_of_get_next_endpoint(node, ep);
+		ep = of_graph_get_next_endpoint(node, ep);
 		if (!ep)
 			break;
 

@@ -206,7 +206,7 @@ static int rcar_du_encoders_init_one(struct rcar_du_device *rcdu,
 	enum rcar_du_encoder_type enc_type = RCAR_DU_ENCODER_NONE;
 	struct device_node *connector = NULL;
 	struct device_node *encoder = NULL;
-	struct device_node *prev = NULL;
+	struct device_node *ep_node = NULL;
 	struct device_node *entity_ep_node;
 	struct device_node *entity;
 	int ret;

@@ -225,11 +225,7 @@ static int rcar_du_encoders_init_one(struct rcar_du_device *rcdu,
 	entity_ep_node = of_parse_phandle(ep->local_node, "remote-endpoint", 0);
 
 	while (1) {
-		struct device_node *ep_node;
-
-		ep_node = of_graph_get_next_endpoint(entity, prev);
-		of_node_put(prev);
-		prev = ep_node;
+		ep_node = of_graph_get_next_endpoint(entity, ep_node);
 
 		if (!ep_node)
 			break;

@@ -300,7 +296,7 @@ static int rcar_du_encoders_init_one(struct rcar_du_device *rcdu,
 static int rcar_du_encoders_init(struct rcar_du_device *rcdu)
 {
 	struct device_node *np = rcdu->dev->of_node;
-	struct device_node *prev = NULL;
+	struct device_node *ep_node = NULL;
 	unsigned int num_encoders = 0;
 
 	/*

@@ -308,15 +304,12 @@ static int rcar_du_encoders_init(struct rcar_du_device *rcdu)
 	 * pipeline.
 	 */
 	while (1) {
-		struct device_node *ep_node;
 		enum rcar_du_output output;
 		struct of_endpoint ep;
 		unsigned int i;
 		int ret;
 
-		ep_node = of_graph_get_next_endpoint(np, prev);
-		of_node_put(prev);
-		prev = ep_node;
+		ep_node = of_graph_get_next_endpoint(np, ep_node);
 
 		if (ep_node == NULL)
 			break;

@@ -1710,7 +1710,6 @@ static void scan_of_host(struct soc_camera_host *ici)
 		if (!i)
 			soc_of_bind(ici, epn, ren->parent);
 
-		of_node_put(epn);
 		of_node_put(ren);
 
 		if (i) {

@@ -1718,6 +1717,8 @@ static void scan_of_host(struct soc_camera_host *ici)
 			break;
 		}
 	}
+
+	of_node_put(epn);
 }
 
 #else

@@ -2085,8 +2085,7 @@ EXPORT_SYMBOL(of_graph_parse_endpoint);
  * @prev: previous endpoint node, or NULL to get first
  *
  * Return: An 'endpoint' node pointer with refcount incremented. Refcount
- * of the passed @prev node is not decremented, the caller have to use
- * of_node_put() on it when done.
+ * of the passed @prev node is decremented.
  */
 struct device_node *of_graph_get_next_endpoint(const struct device_node *parent,
 					struct device_node *prev)

@@ -2122,12 +2121,6 @@ struct device_node *of_graph_get_next_endpoint(const struct device_node *parent,
 		if (WARN_ONCE(!port, "%s(): endpoint %s has no parent node\n",
 			      __func__, prev->full_name))
 			return NULL;
-
-		/*
-		 * Avoid dropping prev node refcount to 0 when getting the next
-		 * child below.
-		 */
-		of_node_get(prev);
 	}
 
 	while (1) {

@@ -2080,6 +2080,32 @@ int of_graph_parse_endpoint(const struct device_node *node,
 EXPORT_SYMBOL(of_graph_parse_endpoint);
 
 /**
+ * of_graph_get_port_by_id() - get the port matching a given id
+ * @parent: pointer to the parent device node
+ * @id: id of the port
+ *
+ * Return: A 'port' node pointer with refcount incremented. The caller
+ * has to use of_node_put() on it when done.
+ */
+struct device_node *of_graph_get_port_by_id(struct device_node *node, u32 id)
+{
+	struct device_node *port;
+
+	for_each_child_of_node(node, port) {
+		u32 port_id = 0;
+
+		if (of_node_cmp(port->name, "port") != 0)
+			continue;
+		of_property_read_u32(port, "reg", &port_id);
+		if (id == port_id)
+			return port;
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL(of_graph_get_port_by_id);
+
+/**
  * 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

@@ -40,6 +40,7 @@ struct of_endpoint {
 #ifdef CONFIG_OF
 int of_graph_parse_endpoint(const struct device_node *node,
 				struct of_endpoint *endpoint);
+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_remote_port_parent(

@@ -53,6 +54,12 @@ static inline int of_graph_parse_endpoint(const struct device_node *node,
 	return -ENOSYS;
 }
 
+static inline struct device_node *of_graph_get_port_by_id(
+					struct device_node *node, u32 id)
+{
+	return NULL;
+}
+
 static inline struct device_node *of_graph_get_next_endpoint(
 					const struct device_node *parent,
 					struct device_node *previous)

@@ -26,6 +26,17 @@ struct of_endpoint {
 	const struct device_node *local_node;
 };
 
+/**
+ * for_each_endpoint_of_node - iterate over every endpoint in a device node
+ * @parent: parent device node containing ports and endpoints
+ * @child: loop variable pointing to the current endpoint node
+ *
+ * When breaking out of the loop, of_node_put(child) has to be called manually.
+ */
+#define for_each_endpoint_of_node(parent, child) \
+	for (child = of_graph_get_next_endpoint(parent, NULL); child != NULL; \
+	     child = of_graph_get_next_endpoint(parent, child))
+
 #ifdef CONFIG_OF
 int of_graph_parse_endpoint(const struct device_node *node,
 				struct of_endpoint *endpoint);