[PATCH v4 01/14] device property: Add fwnode_graph_get_port_by_id()

[Chen-Yu Tsai <wenst@chromium.org>]

In some cases the driver needs a reference to the port firmware node.
Once such case is the upcoming USB power sequencing integration. The
USB hub port is tied to the corresponding port firmware node if it
exists.

Provide a helper for this.

Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
---
Changes since v2:
- Moved "Return:" kernel-doc section to the end. (Andy)

Changes since v1:
- New patch
---
 drivers/base/property.c  | 22 ++++++++++++++++++++++
 include/linux/property.h |  1 +
 2 files changed, 23 insertions(+)

diff --git a/drivers/base/property.c b/drivers/base/property.c
index 9387bb83eb54..3e3e19ef66a9 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -1346,6 +1346,28 @@ int fwnode_graph_parse_endpoint(const struct fwnode_handle *fwnode,
 }
 EXPORT_SYMBOL(fwnode_graph_parse_endpoint);
 
+/**
+ * fwnode_graph_get_port_by_id - get the port matching a given id
+ * @fwnode: parent fwnode_handle containing the graph
+ * @id: id of the port
+ *
+ * The caller is responsible for calling fwnode_handle_put() on the returned
+ * fwnode pointer.
+ *
+ * Return: A 'port' firmware node pointer with refcount incremented.
+ */
+struct fwnode_handle *fwnode_graph_get_port_by_id(struct fwnode_handle *fwnode, u32 id)
+{
+	struct fwnode_handle *ep;
+
+	ep = fwnode_graph_get_endpoint_by_id(fwnode, id, 0, FWNODE_GRAPH_ENDPOINT_NEXT);
+	if (!ep)
+		return NULL;
+
+	return fwnode_get_next_parent(ep);
+}
+EXPORT_SYMBOL_GPL(fwnode_graph_get_port_by_id);
+
 const void *device_get_match_data(const struct device *dev)
 {
 	return fwnode_call_ptr_op(dev_fwnode(dev), device_get_match_data, dev);
diff --git a/include/linux/property.h b/include/linux/property.h
index 14c304db4664..e04901c0bd8f 100644
--- a/include/linux/property.h
+++ b/include/linux/property.h
@@ -505,6 +505,7 @@ int fwnode_get_phy_mode(const struct fwnode_handle *fwnode);
 
 void __iomem *fwnode_iomap(struct fwnode_handle *fwnode, int index);
 
+struct fwnode_handle *fwnode_graph_get_port_by_id(struct fwnode_handle *fwnode, u32 id);
 struct fwnode_handle *fwnode_graph_get_next_endpoint(
 	const struct fwnode_handle *fwnode, struct fwnode_handle *prev);
 struct fwnode_handle *
-- 
2.55.0.795.g602f6c329a-goog