thunderbolt: Add Thunderbolt/USB4 <-> USB3 match function

This function checks whether given USB4 port device matches with USB3.x
port device, using ACPI _DSD property.

It is designed to be used by component framework to match
USB4 ports with Type-C ports they are connected to.

Also, added USB4 config stub in case mapping function is not reachable.

Signed-off-by: Alan Borzeszkowski <[e-mail]>
Reviewed-by: Heikki Krogerus <[e-mail]>
Signed-off-by: Mika Westerberg <[e-mail]>

drivers/thunderbolt/usb4_port.c

···
 	tb_acpi_power_off_retimers(port);
 }
 
+/**
+ * usb4_usb3_port_match() - Matches USB4 port device with USB 3.x port device
+ * @usb4_port_dev: USB4 port device
+ * @usb3_port_fwnode: USB 3.x port firmware node
+ *
+ * Checks if USB 3.x port @usb3_port_fwnode is tunneled through USB4 port @usb4_port_dev.
+ * Returns true if match is found, false otherwise.
+ *
+ * Function is designed to be used with component framework (component_match_add).
+ */
+bool usb4_usb3_port_match(struct device *usb4_port_dev,
+			  const struct fwnode_handle *usb3_port_fwnode)
+{
+	struct fwnode_handle *nhi_fwnode __free(fwnode_handle) = NULL;
+	struct usb4_port *usb4;
+	struct tb_switch *sw;
+	struct tb_nhi *nhi;
+	u8 usb4_port_num;
+	struct tb *tb;
+
+	usb4 = tb_to_usb4_port_device(usb4_port_dev);
+	if (!usb4)
+		return false;
+
+	sw = usb4->port->sw;
+	tb = sw->tb;
+	nhi = tb->nhi;
+
+	nhi_fwnode = fwnode_find_reference(usb3_port_fwnode, "usb4-host-interface", 0);
+	if (IS_ERR(nhi_fwnode))
+		return false;
+
+	/* Check if USB3 fwnode references same NHI where USB4 port resides */
+	if (!device_match_fwnode(&nhi->pdev->dev, nhi_fwnode))
+		return false;
+
+	if (fwnode_property_read_u8(usb3_port_fwnode, "usb4-port-number", &usb4_port_num))
+		return false;
+
+	return usb4_port_index(sw, usb4->port) == usb4_port_num;
+}
+EXPORT_SYMBOL_GPL(usb4_usb3_port_match);
+
 static ssize_t offline_show(struct device *dev,
 	struct device_attribute *attr, char *buf)
 {
···
 		return ERR_PTR(ret);
 	}
 
-	if (dev_fwnode(&usb4->dev)) {
-		ret = component_add(&usb4->dev, &connector_ops);
-		if (ret) {
-			dev_err(&usb4->dev, "failed to add component\n");
-			device_unregister(&usb4->dev);
-		}
+	ret = component_add(&usb4->dev, &connector_ops);
+	if (ret) {
+		dev_err(&usb4->dev, "failed to add component\n");
+		device_unregister(&usb4->dev);
 	}
 
 	if (!tb_is_upstream_port(port))
···
  */
 void usb4_port_device_remove(struct usb4_port *usb4)
 {
-	if (dev_fwnode(&usb4->dev))
-		component_del(&usb4->dev, &connector_ops);
+	component_del(&usb4->dev, &connector_ops);
 	device_unregister(&usb4->dev);
 }
 

include/linux/thunderbolt.h

···
 #ifndef THUNDERBOLT_H_
 #define THUNDERBOLT_H_
 
+#include <linux/types.h>
+
+struct fwnode_handle;
+struct device;
+
+#if IS_REACHABLE(CONFIG_USB4)
+
 #include <linux/device.h>
 #include <linux/idr.h>
 #include <linux/list.h>
···
 {
 	return &ring->nhi->pdev->dev;
 }
+
+bool usb4_usb3_port_match(struct device *usb4_port_dev,
+			  const struct fwnode_handle *usb3_port_fwnode);
+
+#else /* CONFIG_USB4 */
+static inline bool usb4_usb3_port_match(struct device *usb4_port_dev,
+					const struct fwnode_handle *usb3_port_fwnode)
+{
+	return false;
+}
+#endif /* CONFIG_USB4 */
 
 #endif /* THUNDERBOLT_H_ */