Intel Extensible Firmware Interface - Manual (Page 596)

Extensible Firmware Interface Specification
14-56 12/01/02 Version 1.10
EFI_USB_IO_PROTOCOL.UsbGetConfigDescriptor()
Summary
Retrieves the USB Device Configuration Descriptor.
Prototype
typedef
EFI_STATUS
(EFIAPI *EFI_USB_IO_GET_CONFIG_DESCRIPTOR) (
IN EFI_USB_IO_PROTOCOL
*This,
OUT EFI_USB_CONFIG_DESCRIPTOR *ConfigurationDescriptor
);
Parameters
This A pointer to the EFI_USB_IO_PROTOCOL instance. Type
EFI_USB_IO_PROTOCOL is defined in Section 14.2.5.
ConfigurationDescriptor A pointer to the caller allocated USB Active Configuration
Descriptor. See “Related Definitions” for a detailed
description.
Related Definitions
//
// See USB1.1 for detail descrption.
//
typedef struct {
UINT8
Length;
UINT8 DescriptorType;
UINT16 TotalLength;
UINT8 NumInterfaces;
UINT8 ConfigurationValue;
UINT8 Configuration;
UINT8 Attributes;
UINT8 MaxPower;
} EFI_USB_CONFIG_DESCRIPTOR;
Description
This function is used to retrieve the active configuration that the USB device is currently using. If
ConfigurationDescriptor is NULL , then EFI_INVALID_PARAMETER is returned. If the
USB controller does not contain an active configuration, then EFI_NOT_FOUND is returned.
Otherwise, the active configuration is returned in ConfigurationDescriptor , and
EFI_SUCCESS is returned.
Status Code Returned
EFI_SUCCESS The active configuration descriptor was retrieved successfully.
EFI_INVALID_PARAMETER ConfigurationDescriptor is NULL.
EFI_NOT_FOUND An active configuration descriptor cannot be found. The device may not
be configured.