2 files changed, 10 insertions, 2 deletions

diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index 020b58528d90..f026991d0bdf 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -375,18 +375,24 @@ struct usb_device *usb_alloc_dev(struct usb_device *parent,
          */
         if (unlikely(!parent)) {
                 dev->devpath[0] = '0';
+                dev->route = 0;
 
                 dev->dev.parent = bus->controller;
                 dev_set_name(&dev->dev, "usb%d", bus->busnum);
                 root_hub = 1;
         } else {
                 /* match any labeling on the hubs; it's one-based */
-                if (parent->devpath[0] == '0')
+                if (parent->devpath[0] == '0') {
                         snprintf(dev->devpath, sizeof dev->devpath,
                                 "%d", port1);
-                else
+                        /* Root ports are not counted in route string */
+                        dev->route = 0;
+                } else {
                         snprintf(dev->devpath, sizeof dev->devpath,
                                 "%s.%d", parent->devpath, port1);
+                        dev->route = parent->route +
+                                (port1 << ((parent->level - 1)*4));
+                }
 
                 dev->dev.parent = &parent->dev;
                 dev_set_name(&dev->dev, "%d-%s", bus->busnum, dev->devpath);
diff --git a/include/linux/usb.h b/include/linux/usb.h
index fb1f2a32ae05..2b380a16c62f 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -362,6 +362,7 @@ struct usb_tt;
  * struct usb_device - kernel's representation of a USB device
  * @devnum: device number; address on a USB bus
  * @devpath: device ID string for use in messages (e.g., /port/...)
+ * @route: tree topology hex string for use with xHCI
  * @state: device state: configured, not attached, etc.
  * @speed: device speed: high/full/low (or error)
  * @tt: Transaction Translator info; used with low/full speed dev, highspeed hub
@@ -427,6 +428,7 @@ struct usb_tt;
 struct usb_device {
         int             devnum;
         char            devpath [16];
+        u32             route;
         enum usb_device_state   state;
         enum usb_device_speed   speed;