ports/core/libusb

To access raw USB devices (those not treated as a disk by the mass-storage driver),
appropriate support must be available in the kernel. Check your kernel configuration:

Device Drivers --->
  [*] USB support --->                   [CONFIG_USB_SUPPORT]
    <*/M> Support for Host-side USB      [CONFIG_USB]
    (Select any USB hardware device drivers you may need on the same page)