int usb_new_device (struct usb_device * udev);
This is called with devices which have been enumerated, but not yet configured. The device descriptor is available, but not descriptors for any device configuration. The caller must have locked udev and either the parent hub (if udev is a normal device) or else the usb_bus_list_lock (if udev is a root hub). The parent's pointer to udev has already been installed, but udev is not yet visible through sysfs or other filesystem code.
Returns 0 for success (device is configured and listed, with its interfaces, in sysfs); else a negative errno value.
This call is synchronous, and may not be used in an interrupt context.
Only the hub driver should ever call this; root hub registration uses it indirectly.