/**
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* @file UsbDescriptors.c
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* @brief Functions to read USB Interface and Capabilities descriptors
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*
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* Copyright (c) 2018-2019, DisplayLink (UK) Ltd. All rights reserved.
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*
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* SPDX-License-Identifier: BSD-2-Clause-Patent
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*
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**/
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#include "UsbDisplayLink.h"
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#include "UsbDescriptors.h"
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/**
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*
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* @param UsbIo
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* @param descriptorType
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* @param index
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* @param Buffer
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* @param Length
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* @param UsbStatus
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* @return
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*/
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STATIC EFI_STATUS
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ReadDescriptor (
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IN EFI_USB_IO_PROTOCOL *UsbIo,
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UINT8 DescriptorType,
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UINT8 Index,
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VOID* Buffer,
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UINT16 Length,
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UINT32* UsbStatus)
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{
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EFI_STATUS Status;
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UINT8 Header[2];
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ZeroMem (Header, sizeof (Header));
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EFI_USB_DEVICE_REQUEST Request;
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ZeroMem (&Request, sizeof (Request));
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Request.RequestType = USB_ENDPOINT_DIR_IN | USB_REQ_TYPE_STANDARD | USB_TARGET_DEVICE;
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Request.Request = USB_REQ_GET_DESCRIPTOR;
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Request.Index = 0;
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Request.Value = DescriptorType << 8 | Index;
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Request.Length = sizeof (Header);
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// Read the descriptor header to see how many bytes it contains
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Status = UsbIo->UsbControlTransfer (
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UsbIo,
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&Request,
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EfiUsbDataIn,
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DISPLAYLINK_USB_CTRL_TIMEOUT,
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Header,
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sizeof (Header),
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UsbStatus);
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if (EFI_ERROR (Status)) {
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DEBUG ((DEBUG_ERROR, "Failed to read length of descriptor type x%x, index %u (code %r, USB status x%x)\n",
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DescriptorType, Index, Status, *UsbStatus));
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return Status;
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}
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CONST UINT16 TotalLength = Header[0];
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// Now we know the size of it, we can read the entire descriptor
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Request.Length = TotalLength;
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Status = UsbIo->UsbControlTransfer (
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UsbIo,
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&Request,
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EfiUsbDataIn,
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DISPLAYLINK_USB_CTRL_TIMEOUT,
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Buffer,
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TotalLength,
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UsbStatus);
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return Status;
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}
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/**
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Perform a USB control transfer to read the DisplayLink vendor descriptor.
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@param UsbIo Pointer to the instance of the USBIO protocol
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@param Buffer Pointer to the buffer where descriptor should be written
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@param Length Length of buffer (and the maximum amount of descriptor data that shall be read)
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@retval EFI_SUCCESS The descriptor has been copied into Buffer
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@retval Other The descriptor could not be read
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**/
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EFI_STATUS
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ReadCapabilitiesDescriptor (
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IN EFI_USB_IO_PROTOCOL *UsbIo,
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OUT VOID* Buffer,
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IN UINT16 Length)
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{
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UINT32 UsbStatus;
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EFI_STATUS Status;
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Status = ReadDescriptor (
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UsbIo,
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DESCRIPTOR_TYPE_DIRECTFB_CAPABILITY,
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0,
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Buffer,
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Length,
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&UsbStatus);
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if (EFI_ERROR (Status)) {
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DEBUG ((DEBUG_ERROR, "Could not read capabilities descriptor from DL device (code %r, USB status x%x). Unrecognised firmware version?\n", Status, UsbStatus));
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}
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return Status;
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}
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/**
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An alternative to the UBSIO protocol function EFI_USB_IO_GET_INTERFACE_DESCRIPTOR.
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This version allows you to specify an index.
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* @param UsbIo Pointer to the instance of the USBIO protocol
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* @param interfaceDescriptor Where the descriptor should be written
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* @param index The index of the descriptor required (the standard USBIO function doesn't let you do this)
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* @return
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*/
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EFI_STATUS
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UsbDisplayLinkGetInterfaceDescriptor (
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IN EFI_USB_IO_PROTOCOL *UsbIo,
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OUT EFI_USB_INTERFACE_DESCRIPTOR* InterfaceDescriptor,
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UINT8 Index
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)
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{
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UINT32 UsbStatus;
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EFI_STATUS Status;
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Status = ReadDescriptor (
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UsbIo,
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USB_DESC_TYPE_INTERFACE,
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Index,
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InterfaceDescriptor,
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sizeof (EFI_USB_INTERFACE_DESCRIPTOR),
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&UsbStatus);
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if (EFI_ERROR (Status)) {
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DEBUG ((DEBUG_ERROR, "USB control transfer failed while reading interface descriptor (code %r, USB status x%x)\n", Status, UsbStatus));
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}
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return Status;
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}
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