+static struct device_driver usb_port_driver = {
+ .name = "usb",
+ .owner = THIS_MODULE,
+};
+
+static int link_peers(struct usb_port *left, struct usb_port *right)
+{
+ struct usb_port *ss_port, *hs_port;
+ int rc;
+
+ if (left->peer == right && right->peer == left)
+ return 0;
+
+ if (left->peer || right->peer) {
+ struct usb_port *lpeer = left->peer;
+ struct usb_port *rpeer = right->peer;
+ char *method;
+
+ if (left->location && left->location == right->location)
+ method = "location";
+ else
+ method = "default";
+
+ pr_debug("usb: failed to peer %s and %s by %s (%s:%s) (%s:%s)\n",
+ dev_name(&left->dev), dev_name(&right->dev), method,
+ dev_name(&left->dev),
+ lpeer ? dev_name(&lpeer->dev) : "none",
+ dev_name(&right->dev),
+ rpeer ? dev_name(&rpeer->dev) : "none");
+ return -EBUSY;
+ }
+
+ rc = sysfs_create_link(&left->dev.kobj, &right->dev.kobj, "peer");
+ if (rc)
+ return rc;
+ rc = sysfs_create_link(&right->dev.kobj, &left->dev.kobj, "peer");
+ if (rc) {
+ sysfs_remove_link(&left->dev.kobj, "peer");
+ return rc;
+ }
+
+ /*
+ * We need to wake the HiSpeed port to make sure we don't race
+ * setting ->peer with usb_port_runtime_suspend(). Otherwise we
+ * may miss a suspend event for the SuperSpeed port.
+ */
+ if (left->is_superspeed) {
+ ss_port = left;
+ WARN_ON(right->is_superspeed);
+ hs_port = right;
+ } else {
+ ss_port = right;
+ WARN_ON(!right->is_superspeed);
+ hs_port = left;
+ }
+ pm_runtime_get_sync(&hs_port->dev);
+
+ left->peer = right;
+ right->peer = left;
+
+ /*
+ * The SuperSpeed reference is dropped when the HiSpeed port in
+ * this relationship suspends, i.e. when it is safe to allow a
+ * SuperSpeed connection to drop since there is no risk of a
+ * device degrading to its powered-off HiSpeed connection.
+ *
+ * Also, drop the HiSpeed ref taken above.
+ */
+ pm_runtime_get_sync(&ss_port->dev);
+ pm_runtime_put(&hs_port->dev);
+
+ return 0;
+}
+
+static void link_peers_report(struct usb_port *left, struct usb_port *right)
+{
+ int rc;
+
+ rc = link_peers(left, right);
+ if (rc == 0) {
+ dev_dbg(&left->dev, "peered to %s\n", dev_name(&right->dev));
+ } else {
+ dev_dbg(&left->dev, "failed to peer to %s (%d)\n",
+ dev_name(&right->dev), rc);
+ pr_warn_once("usb: port power management may be unreliable\n");
+ usb_port_block_power_off = 1;
+ }
+}
+
+static void unlink_peers(struct usb_port *left, struct usb_port *right)
+{
+ struct usb_port *ss_port, *hs_port;
+
+ WARN(right->peer != left || left->peer != right,
+ "%s and %s are not peers?\n",
+ dev_name(&left->dev), dev_name(&right->dev));
+
+ /*
+ * We wake the HiSpeed port to make sure we don't race its
+ * usb_port_runtime_resume() event which takes a SuperSpeed ref
+ * when ->peer is !NULL.
+ */
+ if (left->is_superspeed) {
+ ss_port = left;
+ hs_port = right;
+ } else {
+ ss_port = right;
+ hs_port = left;
+ }
+
+ pm_runtime_get_sync(&hs_port->dev);
+
+ sysfs_remove_link(&left->dev.kobj, "peer");
+ right->peer = NULL;
+ sysfs_remove_link(&right->dev.kobj, "peer");
+ left->peer = NULL;
+
+ /* Drop the SuperSpeed ref held on behalf of the active HiSpeed port */
+ pm_runtime_put(&ss_port->dev);
+
+ /* Drop the ref taken above */
+ pm_runtime_put(&hs_port->dev);
+}
+
+/*
+ * For each usb hub device in the system check to see if it is in the
+ * peer domain of the given port_dev, and if it is check to see if it
+ * has a port that matches the given port by location
+ */
+static int match_location(struct usb_device *peer_hdev, void *p)
+{
+ int port1;
+ struct usb_hcd *hcd, *peer_hcd;
+ struct usb_port *port_dev = p, *peer;
+ struct usb_hub *peer_hub = usb_hub_to_struct_hub(peer_hdev);
+ struct usb_device *hdev = to_usb_device(port_dev->dev.parent->parent);
+
+ if (!peer_hub)
+ return 0;
+
+ hcd = bus_to_hcd(hdev->bus);
+ peer_hcd = bus_to_hcd(peer_hdev->bus);
+ /* peer_hcd is provisional until we verify it against the known peer */
+ if (peer_hcd != hcd->shared_hcd)
+ return 0;
+
+ for (port1 = 1; port1 <= peer_hdev->maxchild; port1++) {
+ peer = peer_hub->ports[port1 - 1];
+ if (peer && peer->location == port_dev->location) {
+ link_peers_report(port_dev, peer);
+ return 1; /* done */
+ }
+ }
+
+ return 0;
+}
+
+/*
+ * Find the peer port either via explicit platform firmware "location"
+ * data, the peer hcd for root hubs, or the upstream peer relationship
+ * for all other hubs.
+ */
+static void find_and_link_peer(struct usb_hub *hub, int port1)
+{
+ struct usb_port *port_dev = hub->ports[port1 - 1], *peer;
+ struct usb_device *hdev = hub->hdev;
+ struct usb_device *peer_hdev;
+ struct usb_hub *peer_hub;
+
+ /*
+ * If location data is available then we can only peer this port
+ * by a location match, not the default peer (lest we create a
+ * situation where we need to go back and undo a default peering
+ * when the port is later peered by location data)
+ */
+ if (port_dev->location) {
+ /* we link the peer in match_location() if found */
+ usb_for_each_dev(port_dev, match_location);
+ return;
+ } else if (!hdev->parent) {
+ struct usb_hcd *hcd = bus_to_hcd(hdev->bus);
+ struct usb_hcd *peer_hcd = hcd->shared_hcd;
+
+ if (!peer_hcd)
+ return;
+
+ peer_hdev = peer_hcd->self.root_hub;
+ } else {
+ struct usb_port *upstream;
+ struct usb_device *parent = hdev->parent;
+ struct usb_hub *parent_hub = usb_hub_to_struct_hub(parent);
+
+ if (!parent_hub)
+ return;
+
+ upstream = parent_hub->ports[hdev->portnum - 1];
+ if (!upstream || !upstream->peer)
+ return;
+
+ peer_hdev = upstream->peer->child;
+ }
+
+ peer_hub = usb_hub_to_struct_hub(peer_hdev);
+ if (!peer_hub || port1 > peer_hdev->maxchild)
+ return;
+
+ /*
+ * we found a valid default peer, last check is to make sure it
+ * does not have location data
+ */
+ peer = peer_hub->ports[port1 - 1];
+ if (peer && peer->location == 0)
+ link_peers_report(port_dev, peer);
+}
+