usb: Link the ports to the connectors they are attached to

Creating link to the USB Type-C connector for every new port
that is added when possible.
Reviewed-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: NHeikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20211223082349.45616-1-heikki.krogerus@linux.intel.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/ABI/testing/sysfs-bus-usb

@@ -244,6 +244,15 @@ Description:
 		is permitted, "u2" if only u2 is permitted, "u1_u2" if both u1 and
 		u2 are permitted.
 
+What:		/sys/bus/usb/devices/.../<hub_interface>/port<X>/connector
+Date:		December 2021
+Contact:	Heikki Krogerus <heikki.krogerus@linux.intel.com>
+Description:
+		Link to the USB Type-C connector when available. This link is
+		only created when USB Type-C Connector Class is enabled, and
+		only if the system firmware is capable of describing the
+		connection between a port and its connector.
+
 What:		/sys/bus/usb/devices/.../power/usb2_lpm_l1_timeout
 Date:		May 2013
 Contact:	Mathias Nyman <mathias.nyman@linux.intel.com>

drivers/usb/core/port.c

@@ -9,6 +9,7 @@
 
 #include <linux/slab.h>
 #include <linux/pm_qos.h>
+#include <linux/component.h>
 
 #include "hub.h"
 
@@ -528,6 +529,32 @@ static void find_and_link_peer(struct usb_hub *hub, int port1)
 		link_peers_report(port_dev, peer);
 }
 
+static int connector_bind(struct device *dev, struct device *connector, void *data)
+{
+	int ret;
+
+	ret = sysfs_create_link(&dev->kobj, &connector->kobj, "connector");
+	if (ret)
+		return ret;
+
+	ret = sysfs_create_link(&connector->kobj, &dev->kobj, dev_name(dev));
+	if (ret)
+		sysfs_remove_link(&dev->kobj, "connector");
+
+	return ret;
+}
+
+static void connector_unbind(struct device *dev, struct device *connector, void *data)
+{
+	sysfs_remove_link(&connector->kobj, dev_name(dev));
+	sysfs_remove_link(&dev->kobj, "connector");
+}
+
+static const struct component_ops connector_ops = {
+	.bind = connector_bind,
+	.unbind = connector_unbind,
+};
+
 int usb_hub_create_port_device(struct usb_hub *hub, int port1)
 {
 	struct usb_port *port_dev;
@@ -577,6 +604,10 @@ int usb_hub_create_port_device(struct usb_hub *hub, int port1)
 
 	find_and_link_peer(hub, port1);
 
+	retval = component_add(&port_dev->dev, &connector_ops);
+	if (retval)
+		dev_warn(&port_dev->dev, "failed to add component\n");
+
 	/*
 	 * Enable runtime pm and hold a refernce that hub_configure()
 	 * will drop once the PM_QOS_NO_POWER_OFF flag state has been set
@@ -619,5 +650,6 @@ void usb_hub_remove_port_device(struct usb_hub *hub, int port1)
 	peer = port_dev->peer;
 	if (peer)
 		unlink_peers(port_dev, peer);
+	component_del(&port_dev->dev, &connector_ops);
 	device_unregister(&port_dev->dev);
 }