It seems FreeBSD is receiving support for USB 3.0. From the commit bit:

Commit initial version of new XHCI driver which was written from scratch. This driver adds support for USB3.0 devices. The XHCI interface is also backwards compatible to USB2.0 and USB1.0 and will eventually replace the OHCI/UHCI and EHCI drivers.

There will be follow-up commits during the coming week to link the driver into the default kernel build and add missing USB3.0 functionality in the USB core. Currently only the driver files are committed.