Intel Extensible Firmware Interface - Manual (Page 547)

Protocols — USB Support
Version 1.10 12/01/02 14-7
Description
This function is used to retrieve the USB host controller’s current state. The USB Host Controller
Protocol publishes three states for USB host controller, as defined in “Related Definitions” below.
If
State is NULL , then EFI_INVALID_PARAMETER is returned. If a device error occurs while
attempting to retrieve the USB host controllers current state, then EFI_DEVICE_ERROR is
returned. Otherwise, the USB host controller’s current state is returned in State , and
EFI_SUCCESS is returned.
Status Codes Returned
EFI_SUCCESS The state information of the host controller was returned in State .
EFI_INVALID_PARAMETER State is NULL .
EFI_DEVICE_ERROR An error was encountered while attempting to retrieve the host controller’s
current state.