[PATCH v7 06/16] usb: hub: Associate port@ fwnode with USB port device

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

When a USB hub port is connected to a connector in a firmware node
graph, the port itself has a node in the graph.

Associate the port's firmware node with the USB port's device,
usb_port::dev. This is used in later changes for the M.2 slot power
sequencing provider to match against the requesting port.

To avoid potential conflicts with ACPI firmware nodes and then causing
power management issues, only assign the firmware node if the hub's
firmware node is not an ACPI firmware node.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
---
Changes since v5:
- Added extra |struct fwnode_handle *| local variables to shorten lines
  (Andy)
- Added comment about passing fwnode_graph_get_port_by_id() return value
  directly to device_set_node() (Andy)

Changes since v4:
- Dropped unused |hdev| variable
- Added flags for fwnode_graph_get_port_by_id() with
  FWNODE_GRAPH_DEVICE_DISABLED so that even incomplete
  ports can be connected

Changes since v3:
- Added missing fwnode_handle_put()

Changes since v2:
- Skip assignment if hub firmware node is ACPI node
---
 drivers/usb/core/port.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/usb/core/port.c b/drivers/usb/core/port.c
index b4452b665f59..c0a51d9b06a6 100644
--- a/drivers/usb/core/port.c
+++ b/drivers/usb/core/port.c
@@ -7,6 +7,7 @@
  * Author: Lan Tianyu <tianyu.lan@intel.com>
  */
 
+#include <linux/acpi.h>
 #include <linux/kstrtox.h>
 #include <linux/slab.h>
 #include <linux/string_choices.h>
@@ -358,6 +359,11 @@ static void usb_port_device_release(struct device *dev)
 {
 	struct usb_port *port_dev = to_usb_port(dev);
 
+	/*
+	 * At this point ACPI nodes and swnodes have been removed by
+	 * device_platform_notify_remove() in device_del().
+	 */
+	fwnode_handle_put(dev_fwnode(dev));
 	kfree(port_dev->req);
 	kfree(port_dev);
 }
@@ -754,6 +760,7 @@ int usb_hub_create_port_device(struct usb_hub *hub, int port1)
 {
 	struct usb_port *port_dev;
 	struct usb_device *hdev = hub->hdev;
+	struct fwnode_handle *fwnode = dev_fwnode(&hdev->dev);
 	int retval;
 
 	port_dev = kzalloc_obj(*port_dev);
@@ -782,6 +789,24 @@ int usb_hub_create_port_device(struct usb_hub *hub, int port1)
 	port_dev->dev.driver = &usb_port_driver;
 	dev_set_name(&port_dev->dev, "%s-port%d", dev_name(&hub->hdev->dev),
 			port1);
+
+	/*
+	 * ACPI FW nodes are associated later when device_register() happens.
+	 * Skip assigning one here to avoid potential conflicts.
+	 */
+	if (!is_acpi_node(fwnode)) {
+		struct fwnode_handle *port;
+
+		/*
+		 * fwnode_graph_get_port_by_id() returns either a valid fwnode handle
+		 * or NULL. Passing NULL to device_set_node() clears any associated
+		 * fwnode. It is effectively a no-op here, since no fwnode has been
+		 * assigned to the newly created device yet.
+		 */
+		port = fwnode_graph_get_port_by_id(fwnode, port1, FWNODE_GRAPH_DEVICE_DISABLED);
+		device_set_node(&port_dev->dev, port);
+	}
+
 	mutex_init(&port_dev->status_lock);
 	retval = device_register(&port_dev->dev);
 	if (retval) {
-- 
2.55.0.229.g6434b31f56-goog