[PATCH] usb: typec: ucsi: Get the connector fwnode based on reg value

[Prashanth K]

ucsi_find_fwnode() currently maps UCSI connectors to Device tree
connector nodes based on the order in which connector child nodes
are described in DT.

This can fail because the ordering of child nodes isn't guaranteed
in Device-tree. For example, DTB may contain connector@1 before
connector@0, causing connector numbers to be associated with the wrong
fwnode. As a result, role switch and Type-C notifications can be
delivered to the wrong remote endpoints.

Fix this by using the "reg" property of each connector to match
its corresponding fwnode. While at it, if the reg property isn't
present, then fall back to the old method.

Fixes: c1b0bc2dabfa ("usb: typec: Add support for UCSI interface")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Prashanth K <prashanth.k@xxxxxxxxxxxxxxxx>
---
 drivers/usb/typec/ucsi/ucsi.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
index bef3f9b71d71..c1450639c795 100644
--- a/drivers/usb/typec/ucsi/ucsi.c
+++ b/drivers/usb/typec/ucsi/ucsi.c
@@ -1801,10 +1801,21 @@ static struct fwnode_handle *ucsi_find_fwnode(struct ucsi_connector *con)
 {
 	struct fwnode_handle *fwnode;
 	int i = 1;
+	int ret;
+	u32 port;
 
-	device_for_each_child_node(con->ucsi->dev, fwnode)
-		if (i++ == con->num)
-			return fwnode;
+	device_for_each_child_node(con->ucsi->dev, fwnode) {
+		ret = fwnode_property_read_u32(fwnode, "reg", &port);
+		if (ret < 0) {
+			if (i == con->num)
+				return fwnode;
+		} else {
+			if (port == con->num - 1)
+				return fwnode;
+		}
+
+		i++;
+	}
 	return NULL;
 }
 
-- 
2.34.1