USB Host Controller Interface
USB 控制器的接口标准：
- OHCI: Open Host Controller Interface, USB 1.1
- UHCI: Universal Host Controller Interface by Intel, USB 1.1
- EHCI: Enhanced Host Controller Interface, USB 2.0
- xHCI: eXtensible Host Controller Interface, USB 1.1-3.0
- VHCI: Virtual Host Controller Interface for USB/IP