Intel Extensible Firmware Interface - Manual (Page 595)

Protocols — USB Support
Version 1.10 12/01/02 14-55
Description
This function is used to retrieve information about USB devices. This information includes the
device class, subclass, and the number of configurations the USB device supports. If
DeviceDescriptor is NULL , then EFI_INVALID_PARAMETER is returned. If the USB
device descriptor is not found, then EFI_NOT_FOUND is returned. Otherwise, the device
descriptor is returned in DeviceDescriptor , and EFI_SUCCESS is returned.
Status Code Returned
EFI_SUCCESS The device descriptor was retrieved successfully.
EFI_INVALID_PARAMETER DeviceDescriptor is NULL.
EFI_NOT_FOUND The device descriptor was not found. The device may not be configured.