audk/SourceLevelDebugPkg/Library/DebugCommunicationLibUsb/DebugCommunicationLibUsb.c

/** @file
  Debug Port Library implementation based on usb debug port.

  Copyright (c) 2010 - 2011, Intel Corporation. All rights reserved.<BR>
  This program and the accompanying materials
  are licensed and made available under the terms and conditions of the BSD License
  which accompanies this distribution.  The full text of the license may be found at
  http://opensource.org/licenses/bsd-license.php.

  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

**/

#include <Base.h>
#include <IndustryStandard/Pci.h>
#include <IndustryStandard/Usb.h>
#include <Library/IoLib.h>
#include <Library/PciLib.h>
#include <Library/PcdLib.h>
#include <Library/TimerLib.h>
#include <Library/DebugCommunicationLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/BaseLib.h>
#include <Library/DebugLib.h>

#define SETUP_PID            0x2D
#define INPUT_PID            0x69
#define OUTPUT_PID           0xE1
#define ERROR_PID            0x55
#define DATA0_PID            0xC3
#define DATA1_PID            0x4B
#define DATA2_PID            0x87
#define MDATA_PID            0x0F
#define ACK_PID              0xD2
#define NAK_PID              0x5A
#define STALL_PID            0x1E
#define NYET_PID             0x96

#define PCI_CAPABILITY_ID_DEBUG_PORT   0x0A
#define USB_DEBUG_PORT_MAX_PACKET_SIZE 0x08

#define USB_DEBUG_PORT_IN_USE     BIT10
#define USB_DEBUG_PORT_ENABLE     BIT28
#define USB_DEBUG_PORT_OWNER      BIT30

#define USB_PORT_LINE_STATUS_LS   0x400
#define USB_PORT_LINE_STATUS_MASK 0xC00

//
// Usb debug device descriptor, which is defined at
// USB2 Debug Device Specification.
//
typedef struct _USB_DEBUG_PORT_DESCRIPTOR {
  UINT8          Length;
  UINT8          DescriptorType;
  UINT8          DebugInEndpoint;
  UINT8          DebugOutEndpoint;
}USB_DEBUG_PORT_DESCRIPTOR;

USB_DEVICE_REQUEST mGetDebugDescriptor = {
  0x80,
  USB_REQ_GET_DESCRIPTOR,
  (UINT16)(0x0A << 8),
  0x0000,
  sizeof(USB_DEBUG_PORT_DESCRIPTOR)
  };

USB_DEVICE_REQUEST mSetDebugFeature = {
  0x0,
  USB_REQ_SET_FEATURE,
  (UINT16)(0x06),
  0x0000,
  0x0
  };

USB_DEVICE_REQUEST mSetDebugAddress = {
  0x0,
  USB_REQ_SET_ADDRESS,
  (UINT16)(0x7F),
  0x0000,
  0x0
  };

//
// Usb debug port register file, which is defined at
// EHCI Specification.
//
typedef struct _USB_DEBUG_PORT_REGISTER {
  UINT32         ControlStatus;
  UINT8          TokenPid;
  UINT8          SendPid;
  UINT8          ReceivedPid;
  UINT8          Reserved1;
  UINT8          DataBuffer[8];
  UINT8          UsbEndPoint;
  UINT8          UsbAddress;
  UINT8          Reserved2;
  UINT8          Reserved3;
}USB_DEBUG_PORT_REGISTER;

#pragma pack(1)
//
// The internal data structure of DEBUG_PORT_HANDLE, which stores some
// important datum which are used across various phases.
//
typedef struct _USB_DEBUG_PORT_HANDLE{
  //
  // The usb debug port memory BAR number in EHCI configuration space.
  //
  UINT8        DebugPortBarNumber;
  BOOLEAN      Initialized;
  //
  // The offset of usb debug port registers in EHCI memory range.
  //
  UINT16       DebugPortOffset;
  //
  // The usb debug port memory BAR address.
  //
  UINTN        UsbDebugPortMemoryBase;
  //
  // The EHCI memory BAR address.
  //
  UINTN        EhciMemoryBase;
  //
  // The Bulk In endpoint toggle bit.
  //
  UINT8        BulkInToggle;
  //
  // The Bulk Out endpoint toggle bit.
  //
  UINT8        BulkOutToggle;
  //
  // The available data length in the following data buffer.
  //
  UINT8        DataCount;
  //
  // The data buffer. Maximum length is 8 bytes.
  //
  UINT8        Data[8];
} USB_DEBUG_PORT_HANDLE;
#pragma pack()

//
// The global variable which can be used after memory is ready.
//
USB_DEBUG_PORT_HANDLE     mUsbDebugPortHandle;

/**
  Calculate the usb debug port bar address.

  @param  DebugPortOffset    Get usb debug port offset in the usb debug port memory space.
  @param  DebugPortBarNumbar Get the bar number at which usb debug port is located.

  @retval RETURN_UNSUPPORTED The usb host controller does not supported usb debug port capability.
  @retval RETURN_SUCCESS     Get bar and offset successfully.

**/
RETURN_STATUS
EFIAPI
CalculateUsbDebugPortBar (
  OUT UINT16     *DebugPortOffset,
  OUT UINT8      *DebugPortBarNumbar
 )
{
  UINT16     PciStatus;
  UINT16     VendorId;
  UINT16     DeviceId;
  UINT8      ProgInterface;
  UINT8      SubClassCode;
  UINT8      BaseCode;
  UINT8      CapabilityPtr;
  UINT8      CapabilityId;

  VendorId = PciRead16 (PcdGet32(PcdUsbEhciPciAddress) + PCI_VENDOR_ID_OFFSET);
  DeviceId = PciRead16 (PcdGet32(PcdUsbEhciPciAddress) + PCI_DEVICE_ID_OFFSET);
  
  if ((VendorId == 0xFFFF) || (DeviceId == 0xFFFF)) {
    return RETURN_UNSUPPORTED;
  }

  ProgInterface = PciRead8 (PcdGet32(PcdUsbEhciPciAddress) + PCI_CLASSCODE_OFFSET);
  SubClassCode  = PciRead8 (PcdGet32(PcdUsbEhciPciAddress) + PCI_CLASSCODE_OFFSET + 1);
  BaseCode      = PciRead8 (PcdGet32(PcdUsbEhciPciAddress) + PCI_CLASSCODE_OFFSET + 2);
  
  if ((ProgInterface != PCI_IF_EHCI) || (SubClassCode != PCI_CLASS_SERIAL_USB) || (BaseCode != PCI_CLASS_SERIAL)) {
    return RETURN_UNSUPPORTED;
  }

  //
  // Enable Ehci Host Controller MMIO Space.
  //
  PciStatus = PciRead16 (PcdGet32(PcdUsbEhciPciAddress) + PCI_PRIMARY_STATUS_OFFSET);

  if ((PciStatus & EFI_PCI_STATUS_CAPABILITY) == 0) {
    //
    // The Pci Device Doesn't Support Capability Pointer.
    //
    return RETURN_UNSUPPORTED;
  }

  //
  // Get Pointer To Capability List
  //
  CapabilityPtr = PciRead8(PcdGet32(PcdUsbEhciPciAddress) + PCI_CAPBILITY_POINTER_OFFSET);

  //
  // Find Capability ID 0xA, Which Is For Debug Port
  //
  while (CapabilityPtr != 0) {
    CapabilityId = PciRead8(PcdGet32(PcdUsbEhciPciAddress) + CapabilityPtr);
    if (CapabilityId == PCI_CAPABILITY_ID_DEBUG_PORT) {
      break;
    }
    CapabilityPtr = PciRead8(PcdGet32(PcdUsbEhciPciAddress) + CapabilityPtr + 1);
  }

  //
  // No Debug Port Capability Found
  //
  if (CapabilityPtr == 0) {
    return RETURN_UNSUPPORTED;
  }

  //
  // Get The Base Address Of Debug Port Register In Debug Port Capability Register
  //
  *DebugPortOffset    = (UINT16)(PciRead16(PcdGet32(PcdUsbEhciPciAddress) + CapabilityPtr + 2) & 0x1FFF);
  *DebugPortBarNumbar = (UINT8)((PciRead16(PcdGet32(PcdUsbEhciPciAddress) + CapabilityPtr + 2) >> 13) - 1);

  return RETURN_SUCCESS;
}

/**
  Do a usb IN transaction by usb debug port.

  @param  DebugPortRegister        Pointer to the base address of usb debug port register interface.
  @param  Buffer                   Pointer to the buffer receiving data.
  @param  Length                   Number of bytes of the received data.
  @param  Token                    The token PID for each USB transaction.
  @param  Addr                     The usb device address for usb transaction.
  @param  Ep                       The endpoint for usb transaction.
  @param  DataToggle               The toggle bit used at usb transaction.

  @retval RETURN_SUCCESS           The IN transaction is executed successfully.
  @retval RETURN_INVALID_PARAMETER The parameters passed in are invalid.
  @retval RETURN_DEVICE_ERROR      The IN transaction comes across error.

**/
RETURN_STATUS
EFIAPI
UsbDebugPortIn (
  IN      USB_DEBUG_PORT_REGISTER         *DebugPortRegister,
  IN  OUT UINT8                           *Buffer,
      OUT UINT8                           *Length,
  IN      UINT8                           Token,
  IN      UINT8                           Addr,
  IN      UINT8                           Ep,
  IN      UINT8                           DataToggle
  )
{
  UINTN                   Index;

  if (Length == NULL) {
    return RETURN_INVALID_PARAMETER;
  }
  *Length = 0;

  DebugPortRegister->TokenPid = Token;
  if (DataToggle != 0) {
    DebugPortRegister->SendPid = DATA1_PID;
  } else {
    DebugPortRegister->SendPid = DATA0_PID;
  }

  DebugPortRegister->UsbAddress  = (UINT8)(Addr & 0x7F);
  DebugPortRegister->UsbEndPoint = (UINT8)(Ep & 0xF);

  //
  // Clearing W/R bit to indicate it's a READ operation
  //
  MmioAnd32((UINTN)&DebugPortRegister->ControlStatus, (UINT32)~BIT4);

  //
  // Setting GO bit as well as clearing DONE bit
  //
  MmioOr32((UINTN)&DebugPortRegister->ControlStatus, (UINT32)BIT5);

  //
  // Wait for completing the request
  //
  while ((MmioRead32((UINTN)&DebugPortRegister->ControlStatus) & (UINT32)BIT16) == 0);

  //
  // Check if the request is executed successfully or not.
  //
  if ((MmioRead32((UINTN)&DebugPortRegister->ControlStatus)) & BIT6) {
    return RETURN_DEVICE_ERROR;
  }

  //
  // Make sure the received data are not beyond the allowable maximum length - 8 byte
  //
  if (((MmioRead32((UINTN)&DebugPortRegister->ControlStatus)) & 0xF) > USB_DEBUG_PORT_MAX_PACKET_SIZE) {
    return RETURN_DEVICE_ERROR;
  }

  *Length = (UINT8)(MmioRead32((UINTN)&DebugPortRegister->ControlStatus) & 0xF);
  if (*Length > 8) {
    return RETURN_DEVICE_ERROR;
  }

  for (Index = 0; Index < *Length; Index++) {
    Buffer[Index] = DebugPortRegister->DataBuffer[Index];
  }
  return RETURN_SUCCESS;
}

/**
  Do a usb SETUP/OUT transaction by usb debug port.

  @param  DebugPortRegister        Pointer to the base address of usb debug port register interface.
  @param  Buffer                   Pointer to the buffer receiving data.
  @param  Length                   Number of bytes of the received data.
  @param  Token                    The token PID for each USB transaction.
  @param  Addr                     The usb device address for usb transaction.
  @param  Ep                       The endpoint for usb transaction.
  @param  DataToggle               The toggle bit used at usb transaction.

  @retval RETURN_SUCCESS           The IN transaction is executed successfully.
  @retval RETURN_INVALID_PARAMETER The parameters passed in are invalid.
  @retval RETURN_DEVICE_ERROR      The IN transaction comes across error.

**/
RETURN_STATUS
EFIAPI
UsbDebugPortOut (
  IN  USB_DEBUG_PORT_REGISTER         *DebugPortRegister,
  IN  UINT8                           *Buffer,
  IN  UINT8                           Length,
  IN  UINT8                           Token,
  IN  UINT8                           Addr,
  IN  UINT8                           Ep,
  IN  UINT8                           DataToggle
  )
{
  UINT8             Index;

  if (Length > 8) {
    return RETURN_INVALID_PARAMETER;
  }

  DebugPortRegister->TokenPid = Token;
  if (DataToggle != 0) {
    DebugPortRegister->SendPid = DATA1_PID;
  } else {
    DebugPortRegister->SendPid = DATA0_PID;
  }
  DebugPortRegister->UsbAddress  = (UINT8)(Addr & 0x7F);
  DebugPortRegister->UsbEndPoint = (UINT8)(Ep & 0xF);

  //
  // Fill in the data length and corresponding data.
  //
  MmioAnd32((UINTN)&DebugPortRegister->ControlStatus, (UINT32)~0xF);
  MmioOr32((UINTN)&DebugPortRegister->ControlStatus, Length & 0xF);
  for (Index = 0; Index < Length; Index++) {
    DebugPortRegister->DataBuffer[Index] = Buffer[Index];
  }

  //
  // Setting W/R bit to indicate it's a WRITE operation
  //
  MmioOr32((UINTN)&DebugPortRegister->ControlStatus, BIT4);
  //
  // Setting GO bit as well as clearing DONE bit
  //
  MmioOr32((UINTN)&DebugPortRegister->ControlStatus, BIT5);

  //
  // Wait for completing the request
  //
  while ((MmioRead32((UINTN)&DebugPortRegister->ControlStatus) & BIT16) == 0);

  //
  // Check if the request is executed successfully or not.
  //
  if ((MmioRead32((UINTN)&DebugPortRegister->ControlStatus)) & BIT6) {
    return RETURN_DEVICE_ERROR;
  }

  //
  // Make sure the sent data are not beyond the allowable maximum length - 8 byte
  //
  if (((MmioRead32((UINTN)&DebugPortRegister->ControlStatus)) & 0xF) > USB_DEBUG_PORT_MAX_PACKET_SIZE) {
    return RETURN_DEVICE_ERROR;
  }

  return RETURN_SUCCESS;
}

/**
  Do a usb control transfer by usb debug port.

  @param  DebugPortRegister        Pointer to the base address of usb debug port register interface.
  @param  SetupPacket              The token PID for each USB transaction.
  @param  Addr                     The usb device address for usb transaction.
  @param  Ep                       The endpoint for usb transaction.
  @param  Data                     Pointer to the buffer receiving data.
  @param  DataLength               Number of bytes of the received data.

  @retval RETURN_SUCCESS           The IN transaction is executed successfully.
  @retval RETURN_INVALID_PARAMETER The parameters passed in are invalid.
  @retval RETURN_DEVICE_ERROR      The IN transaction comes across error.

**/
RETURN_STATUS
EFIAPI
UsbDebugPortControlTransfer (
  IN      USB_DEBUG_PORT_REGISTER         *DebugPortRegister,
  IN      USB_DEVICE_REQUEST              *SetupPacket,
  IN      UINT8                           Addr,
  IN      UINT8                           Ep,
      OUT UINT8                           *Data,
  IN  OUT UINT8                           *DataLength
  )
{
  RETURN_STATUS          Status;
  UINT8                  Temp;
  UINT8                  ReturnStatus[8];

  //
  // Setup Phase
  //
  Status = UsbDebugPortOut(DebugPortRegister, (UINT8 *)SetupPacket, (UINT8)sizeof(USB_DEVICE_REQUEST), SETUP_PID, Addr, Ep, 0);
  if (RETURN_ERROR(Status)) {
    return Status;
  }

  //
  // Data Phase
  //
  if (DataLength != 0) {
    if ((SetupPacket->RequestType & BIT7) != 0) {
      //
      // Get Data From Device
      //
      Status = UsbDebugPortIn(DebugPortRegister, Data, DataLength, INPUT_PID, Addr, Ep, 1);
      if (RETURN_ERROR(Status)) {
        return Status;
      }
    } else {
      //
      // Send Data To Device
      //
      Status = UsbDebugPortOut(DebugPortRegister, Data, *DataLength, OUTPUT_PID, Addr, Ep, 1);
      if (RETURN_ERROR(Status)) {
        return Status;
      }
    }
  }

  //
  // Status Phase
  //
  if ((SetupPacket->RequestType & BIT7) != 0) {
    //
    // For READ operation, Data Toggle in Status Phase Should be 1.
    //
    Status = UsbDebugPortOut(DebugPortRegister, NULL, 0, OUTPUT_PID, Addr, Ep, 1);
  } else {
    //
    // For WRITE operation, Data Toggle in Status Phase Should be 1.
    //
    Status = UsbDebugPortIn(DebugPortRegister, ReturnStatus, &Temp, INPUT_PID, Addr, Ep, 1);
  }

  return Status;
}

/**
  Check if it needs to re-initialize usb debug port hardware.

  During different phases switch, such as SEC to PEI or PEI to DXE or DXE to SMM, we should check
  whether the usb debug port hardware configuration is changed. Such case can be triggerred by
  Pci bus resource allocation and so on.

  @param  Handle           Debug port handle.

  @retval TRUE             The usb debug port hardware configuration is changed.
  @retval FALSE            The usb debug port hardware configuration is not changed.

**/
BOOLEAN
EFIAPI
NeedReinitializeHardware(
  IN USB_DEBUG_PORT_HANDLE *Handle
  )
{
  UINT16                  PciCmd;
  UINTN                   UsbDebugPortMemoryBase;
  UINTN                   EhciMemoryBase;
  BOOLEAN                 Status;
  USB_DEBUG_PORT_REGISTER *UsbDebugPortRegister;

  Status = FALSE;

  EhciMemoryBase = 0xFFFFFC00 & PciRead32(PcdGet32(PcdUsbEhciPciAddress) + PCI_BASE_ADDRESSREG_OFFSET);
  if (EhciMemoryBase != Handle->EhciMemoryBase) {
    Handle->EhciMemoryBase = EhciMemoryBase;
    Status = TRUE;
  }

  UsbDebugPortMemoryBase = 0xFFFFFC00 & PciRead32(PcdGet32(PcdUsbEhciPciAddress) + PCI_BASE_ADDRESSREG_OFFSET + Handle->DebugPortBarNumber * 4);
  if (UsbDebugPortMemoryBase != Handle->UsbDebugPortMemoryBase) {
    Handle->UsbDebugPortMemoryBase = UsbDebugPortMemoryBase;
    Status = TRUE;
  }

  //
  // Enable Ehci Memory Space Access
  //
  PciCmd    = PciRead16 (PcdGet32(PcdUsbEhciPciAddress) + PCI_COMMAND_OFFSET);
  if (((PciCmd & EFI_PCI_COMMAND_MEMORY_SPACE) == 0) || ((PciCmd & EFI_PCI_COMMAND_BUS_MASTER) == 0)) {
    Status = TRUE;
  }

  //
  // Check if the debug port is enabled and owned by myself.
  //
  UsbDebugPortRegister = (USB_DEBUG_PORT_REGISTER *)(Handle->UsbDebugPortMemoryBase + Handle->DebugPortOffset);
  if ((MmioRead32((UINTN)&UsbDebugPortRegister->ControlStatus) &
       (USB_DEBUG_PORT_OWNER | USB_DEBUG_PORT_ENABLE | USB_DEBUG_PORT_IN_USE)) == 0) {
    Status = TRUE;
  }
  return Status;
}

/**
  Initialize usb debug port hardware.

  1. reset ehci host controller.
  2. set right port to debug port.
  3. find a usb debug device is attached by getting debug device descriptor.
  4. set address for the usb debug device.
  5. configure the usb debug device to debug mode.

  @param  Handle           Debug port handle.

  @retval TRUE             The usb debug port hardware configuration is changed.
  @retval FALSE            The usb debug port hardware configuration is not changed.

**/
RETURN_STATUS
EFIAPI
InitializeUsbDebugHardware (
  IN USB_DEBUG_PORT_HANDLE *Handle
)
{
  RETURN_STATUS             Status;
  USB_DEBUG_PORT_REGISTER   *UsbDebugPortRegister;
  USB_DEBUG_PORT_DESCRIPTOR UsbDebugPortDescriptor;
  UINT16                    PciCmd;
  UINT32                    *PortStatus;
  UINT32                    *UsbCmd;
  UINT32                    *UsbStatus;
  UINT32                    *UsbHCSParam;
  UINT8                     DebugPortNumber;
  UINT8                     Length;

  UsbDebugPortRegister = (USB_DEBUG_PORT_REGISTER *)(Handle->UsbDebugPortMemoryBase + Handle->DebugPortOffset);
  PciCmd      = PciRead16 (PcdGet32(PcdUsbEhciPciAddress) + PCI_COMMAND_OFFSET);
  UsbHCSParam = (UINT32 *)(Handle->EhciMemoryBase + 0x04);
  UsbCmd      = (UINT32 *)(Handle->EhciMemoryBase + 0x20);
  UsbStatus   = (UINT32 *)(Handle->EhciMemoryBase + 0x24);

  //
  // initialize the data toggle used by bulk in/out endpoint.
  //
  Handle->BulkInToggle  = 0;
  Handle->BulkOutToggle = 0;

  //
  // Enable Ehci Memory Space Access
  //
  if (((PciCmd & EFI_PCI_COMMAND_MEMORY_SPACE) == 0) || ((PciCmd & EFI_PCI_COMMAND_BUS_MASTER) == 0)) {
    PciCmd |= EFI_PCI_COMMAND_MEMORY_SPACE | EFI_PCI_COMMAND_BUS_MASTER;
    PciWrite16(PcdGet32(PcdUsbEhciPciAddress) + PCI_COMMAND_OFFSET, PciCmd);
  }

  //
  // If the host controller is not halted, then halt it.
  //
  if ((MmioRead32((UINTN)UsbStatus) & BIT12) == 0) {
    MmioAnd32((UINTN)UsbCmd, (UINT32)~BIT0);
    while ((MmioRead32((UINTN)UsbStatus) & BIT12) == 0);
  }
  //
  // reset the host controller.
  //
  MmioOr32((UINTN)UsbCmd, BIT1);
  //
  // ensure that the host controller is reset.
  //
  while (MmioRead32((UINTN)UsbCmd) & BIT1);

  //
  // Start the host controller if it's not running
  //
  if (MmioRead32((UINTN)UsbStatus) & BIT12) {
    MmioOr32((UINTN)UsbCmd, BIT0);
    // ensure that the host controller is started (HALTED bit must be cleared)
    while (MmioRead32((UINTN)UsbStatus) & BIT12);
  }

  //
  // First get the ownership of port 0.
  //
  MmioOr32((UINTN)&UsbDebugPortRegister->ControlStatus, USB_DEBUG_PORT_OWNER);

  MicroSecondDelay (200000);

  //
  // Find out which port is used as debug port.
  //
  DebugPortNumber = (UINT8)((MmioRead32((UINTN)UsbHCSParam) & 0x00F00000) >> 20);
  //
  // Should find a non low-speed device is connected
  //
  PortStatus = (UINT32 *)(Handle->EhciMemoryBase + 0x64 + (DebugPortNumber - 1) * 4);
  if (!(MmioRead32((UINTN)PortStatus) & BIT0) || ((MmioRead32((UINTN)PortStatus) & USB_PORT_LINE_STATUS_MASK) == USB_PORT_LINE_STATUS_LS)) {
    return RETURN_NOT_FOUND;
  }

  //
  // Reset the debug port
  //
  MmioOr32((UINTN)PortStatus, BIT8);
  MicroSecondDelay (200000);
  MmioAnd32((UINTN)PortStatus, (UINT32)~BIT8);
  while (MmioRead32((UINTN)PortStatus) & BIT8);

  //
  // The port enabled bit should be set by HW.
  //
  if ((MmioRead32((UINTN)PortStatus) & BIT2) == 0) {
    return RETURN_DEVICE_ERROR;
  }

  //
  // Enable Usb Debug Port Capability
  //
  MmioOr32((UINTN)&UsbDebugPortRegister->ControlStatus, USB_DEBUG_PORT_ENABLE | USB_DEBUG_PORT_IN_USE);

  //
  // Start to communicate with Usb Debug Device to see if the attached device is usb debug device or not.
  //
  Length = (UINT8)sizeof (USB_DEBUG_PORT_DESCRIPTOR);

  //
  // It's not a dedicated usb debug device, should use address 0 to get debug descriptor.
  //
  Status = UsbDebugPortControlTransfer (UsbDebugPortRegister, &mGetDebugDescriptor, 0x0, 0x0, (UINT8*)&UsbDebugPortDescriptor, &Length);
  if (RETURN_ERROR(Status)) {
    //
    // The device is not a usb debug device.
    //
    return Status;
  }

  if (Length != sizeof(USB_DEBUG_PORT_DESCRIPTOR)) {
    return RETURN_DEVICE_ERROR;
  }

  //
  // set usb debug device address as 0x7F.
  //
  Status = UsbDebugPortControlTransfer (UsbDebugPortRegister, &mSetDebugAddress, 0x0, 0x0, NULL, NULL);
  if (RETURN_ERROR(Status)) {
    //
    // The device can not work well.
    //
    return Status;
  }

  //
  // enable the usb debug feature.
  //
  Status = UsbDebugPortControlTransfer (UsbDebugPortRegister, &mSetDebugFeature, 0x7F, 0x0, NULL, NULL);

  return Status;
}

/**
  Read data from debug device and save the datas in buffer.

  Reads NumberOfBytes data bytes from a debug device into the buffer
  specified by Buffer. The number of bytes actually read is returned.
  If the return value is less than NumberOfBytes, then the rest operation failed.
  If NumberOfBytes is zero, then return 0.

  @param  Handle           Debug port handle.
  @param  Buffer           Pointer to the data buffer to store the data read from the debug device.
  @param  NumberOfBytes    Number of bytes which will be read.
  @param  Timeout          Timeout value for reading from debug device. It unit is Microsecond.

  @retval 0                Read data failed, no data is to be read.
  @retval >0               Actual number of bytes read from debug device.

**/
UINTN
EFIAPI
DebugPortReadBuffer (
  IN   DEBUG_PORT_HANDLE    Handle,
  IN   UINT8                *Buffer,
  IN   UINTN                NumberOfBytes,
  IN   UINTN                Timeout
  )
{
  USB_DEBUG_PORT_HANDLE     *UsbDebugPortHandle;
  USB_DEBUG_PORT_REGISTER   *UsbDebugPortRegister;
  RETURN_STATUS             Status;
  UINT8                     Received;
  UINTN                     Total;
  UINTN                     Remaining;
  UINT8                     Index;
  UINT8                     Length;

  if (NumberOfBytes == 0 || Buffer == NULL) {
    return 0;
  }

  Received  = 0;
  Total     = 0;
  Remaining = 0;

  //
  // If Handle is NULL, it means memory is ready for use.
  // Use global variable to store handle value.
  //
  if (Handle == NULL) {
    UsbDebugPortHandle = &mUsbDebugPortHandle;
  } else {
    UsbDebugPortHandle = (USB_DEBUG_PORT_HANDLE *)Handle;
  }

  //
  // Check if debug port is ready
  //
  if (!UsbDebugPortHandle->Initialized) {
    return 0;
  }

  if (NeedReinitializeHardware(UsbDebugPortHandle)) {
    Status = InitializeUsbDebugHardware (UsbDebugPortHandle);
    if (RETURN_ERROR(Status)) {
      return 0;
    }
  }

  UsbDebugPortRegister = (USB_DEBUG_PORT_REGISTER *)(UsbDebugPortHandle->UsbDebugPortMemoryBase + UsbDebugPortHandle->DebugPortOffset);

  //
  // First read data from buffer, then read debug port hw to get received data.
  //
  if (UsbDebugPortHandle->DataCount > 0) {
    if (NumberOfBytes <= UsbDebugPortHandle->DataCount) {
      Total = NumberOfBytes;
    } else {
      Total = UsbDebugPortHandle->DataCount;
    }

    for (Index = 0; Index < Total; Index++) {
      Buffer[Index] = UsbDebugPortHandle->Data[Index];
    }

    for (Index = 0; Index < UsbDebugPortHandle->DataCount - Total; Index++) {
      if (Total + Index >= 8) {
        return 0;
      }
      UsbDebugPortHandle->Data[Index] = UsbDebugPortHandle->Data[Total + Index];
    }
    UsbDebugPortHandle->DataCount = (UINT8)(UsbDebugPortHandle->DataCount - (UINT8)Total);
  }

  //
  // If Timeout is equal to 0, then it means it should always wait until all datum required are received.
  //
  if (Timeout == 0) {
    Timeout = 0xFFFFFFFF;
  }

  //
  // Read remaining data by executing one or more usb debug transfer transactions at usb debug port hw.
  //
  while ((Total < NumberOfBytes) && (Timeout != 0)) {
    Remaining = NumberOfBytes - Total;
    if (Remaining >= USB_DEBUG_PORT_MAX_PACKET_SIZE) {
      Status = UsbDebugPortIn(UsbDebugPortRegister, Buffer + Total, &Received, INPUT_PID, 0x7f, 0x82, UsbDebugPortHandle->BulkInToggle);

      if (RETURN_ERROR(Status)) {
        return Total;
      }
    } else {
        Status = UsbDebugPortIn(UsbDebugPortRegister, &UsbDebugPortHandle->Data[0], &Received, INPUT_PID, 0x7f, 0x82, UsbDebugPortHandle->BulkInToggle);

        if (RETURN_ERROR(Status)) {
          return Total;
        }

        UsbDebugPortHandle->DataCount = Received;

        if (Remaining <= Received) {
          Length = (UINT8)Remaining;
        } else {
          Length = (UINT8)Received;
        }

        //
        // Copy required data from the data buffer to user buffer.
        //
        for (Index = 0; Index < Length; Index++) {
          (Buffer + Total)[Index] = UsbDebugPortHandle->Data[Index];
          UsbDebugPortHandle->DataCount--;
        }

        //
        // reorder the data buffer to make available data arranged from the beginning of the data buffer.
        //
        for (Index = 0; Index < Received - Length; Index++) {
          if (Length + Index >= 8) {
            return 0;
          }
          UsbDebugPortHandle->Data[Index] = UsbDebugPortHandle->Data[Length + Index];
        }
        //
        // fixup the real received length in Buffer.
        //
        Received = Length;
      }
      UsbDebugPortHandle->BulkInToggle ^= 1;

      Total += Received;
      Timeout -= 100;
  }

  return Total;
}

/**
  Write data from buffer to debug device.

  Writes NumberOfBytes data bytes from Buffer to the debug device.
  The number of bytes actually written to the debug device is returned.
  If the return value is less than NumberOfBytes, then the write operation failed.
  If NumberOfBytes is zero, then return 0.

  @param  Handle           Debug port handle.
  @param  Buffer           Pointer to the data buffer to be written.
  @param  NumberOfBytes    Number of bytes to written to the debug device.

  @retval 0                NumberOfBytes is 0.
  @retval >0               The number of bytes written to the debug device.
                           If this value is less than NumberOfBytes, then the read operation failed.

**/
UINTN
EFIAPI
DebugPortWriteBuffer (
  IN   DEBUG_PORT_HANDLE    Handle,
  IN   UINT8                *Buffer,
  IN   UINTN                NumberOfBytes
  )
{
  USB_DEBUG_PORT_HANDLE     *UsbDebugPortHandle;
  USB_DEBUG_PORT_REGISTER   *UsbDebugPortRegister;
  RETURN_STATUS             Status;
  UINT8                     Sent;
  UINTN                     Total;
  UINT8                     ReceivedPid;

  if (NumberOfBytes == 0 || Buffer == NULL) {
    return 0;
  }

  Sent  = 0;
  Total = 0;

  //
  // If Handle is NULL, it means memory is ready for use.
  // Use global variable to store handle value.
  //
  if (Handle == NULL) {
    UsbDebugPortHandle = &mUsbDebugPortHandle;
  } else {
    UsbDebugPortHandle = (USB_DEBUG_PORT_HANDLE *)Handle;
  }

  //
  // Check if debug port is ready
  //
  if (!UsbDebugPortHandle->Initialized) {
    return 0;
  }

  if (NeedReinitializeHardware(UsbDebugPortHandle)) {
    Status = InitializeUsbDebugHardware (UsbDebugPortHandle);
    if (RETURN_ERROR(Status)) {
      return 0;
    }
  }

  UsbDebugPortRegister = (USB_DEBUG_PORT_REGISTER *)(UsbDebugPortHandle->UsbDebugPortMemoryBase + UsbDebugPortHandle->DebugPortOffset);

  while ((Total < NumberOfBytes)) {
    if (NumberOfBytes - Total > USB_DEBUG_PORT_MAX_PACKET_SIZE) {
      Sent = USB_DEBUG_PORT_MAX_PACKET_SIZE;
    } else {
      Sent = (UINT8)(NumberOfBytes - Total);
    }

    Status = UsbDebugPortOut(UsbDebugPortRegister, Buffer + Total, Sent, OUTPUT_PID, 0x7F, 0x01, UsbDebugPortHandle->BulkOutToggle);

    if (RETURN_ERROR(Status)) {
      return Total;
    }

    ReceivedPid = (MmioRead8((UINTN)&UsbDebugPortRegister->ReceivedPid));
    //
    // If received a NAK_PID on write transaction, it means the usb debug device is busy and can not handle this transaction.
    // should send the packet again.
    //
    if (ReceivedPid == NAK_PID) {
      Sent = 0;
    } else {
      UsbDebugPortHandle->BulkOutToggle ^= 1;
    }
    Total += Sent;
  }
  return Total;
}

/**
  Polls a debug device to see if there is any data waiting to be read.

  Polls a debug device to see if there is any data waiting to be read.
  If there is data waiting to be read from the debug device, then TRUE is returned.
  If there is no data waiting to be read from the debug device, then FALSE is returned.

  @param  Handle           Debug port handle.

  @retval TRUE             Data is waiting to be read from the debug device.
  @retval FALSE            There is no data waiting to be read from the serial device.

**/
BOOLEAN
EFIAPI
DebugPortPollBuffer (
  IN DEBUG_PORT_HANDLE      Handle
  )
{
  USB_DEBUG_PORT_HANDLE     *UsbDebugPortHandle;
  USB_DEBUG_PORT_REGISTER   *UsbDebugPortRegister;
  UINT8                     Length;
  UINT8                     Index;
  RETURN_STATUS             Status;

  //
  // If Handle is NULL, it means memory is ready for use.
  // Use global variable to store handle value.
  //
  if (Handle == NULL) {
    UsbDebugPortHandle = &mUsbDebugPortHandle;
  } else {
    UsbDebugPortHandle = (USB_DEBUG_PORT_HANDLE *)Handle;
  }

  //
  // Check if debug port is ready
  //
  if (!UsbDebugPortHandle->Initialized) {
    return 0;
  }

  if (NeedReinitializeHardware(UsbDebugPortHandle)) {
    Status = InitializeUsbDebugHardware(UsbDebugPortHandle);
    if (RETURN_ERROR(Status)) {
      return FALSE;
    }
  }

  //
  // If the data buffer is not empty, then return TRUE directly.
  // else initialize a usb read transaction and read data to the data buffer.
  //
  if (UsbDebugPortHandle->DataCount != 0) {
    return TRUE;
  }

  UsbDebugPortRegister = (USB_DEBUG_PORT_REGISTER *)(UsbDebugPortHandle->UsbDebugPortMemoryBase + UsbDebugPortHandle->DebugPortOffset);

  UsbDebugPortRegister->TokenPid = INPUT_PID;
  if (UsbDebugPortHandle->BulkInToggle == 0) {
    UsbDebugPortRegister->SendPid  = DATA0_PID;
  } else {
    UsbDebugPortRegister->SendPid  = DATA1_PID;
  }
  UsbDebugPortRegister->UsbAddress  = 0x7F;
  UsbDebugPortRegister->UsbEndPoint = 0x82 & 0x0F;

  //
  // Clearing W/R bit to indicate it's a READ operation
  //
  MmioAnd32((UINTN)&UsbDebugPortRegister->ControlStatus, (UINT32)~BIT4);
  //
  // Setting GO bit as well as clearing DONE bit
  //
  MmioOr32((UINTN)&UsbDebugPortRegister->ControlStatus, (UINT32)BIT5);

  //
  // Wait for completing the request
  //
  while ((MmioRead32((UINTN)&UsbDebugPortRegister->ControlStatus) & (UINT32)BIT16) == 0);

  if ((MmioRead32((UINTN)&UsbDebugPortRegister->ControlStatus)) & BIT6) {
    return FALSE;
  }

  Length = (UINT8)(MmioRead32((UINTN)&UsbDebugPortRegister->ControlStatus) & 0xF);

  if (Length > 8) {
    return FALSE;
  }

  UsbDebugPortHandle->BulkInToggle ^= 1;

  if (Length == 0) {
    return FALSE;
  }

  for (Index = 0; Index < Length; Index++) {
    UsbDebugPortHandle->Data[Index] = UsbDebugPortRegister->DataBuffer[Index];
  }
  UsbDebugPortHandle->DataCount = Length;

  return TRUE;
}

/**
  Initialize the debug port.

  If Function is not NULL, Debug Communication Libary will call this function
  by passing in the Context to be the first parameter. If needed, Debug Communication
  Library will create one debug port handle to be the second argument passing in
  calling the Function, otherwise it will pass NULL to be the second argument of
  Function.

  If Function is NULL, and Context is not NULL, the Debug Communication Library could
    a) Return the same handle as passed in (as Context parameter).
    b) Ignore the input Context parameter and create new hanlde to be returned.

  If parameter Function is NULL and Context is NULL, Debug Communication Library could
  created a new handle if needed and return it, otherwise it will return NULL.

  @param[in] Context      Context needed by callback function; it was optional.
  @param[in] Function     Continue function called by Debug Communication library;
                          it was optional.

  @return  The debug port handle created by Debug Communication Library if Function
           is not NULL.

**/
DEBUG_PORT_HANDLE
EFIAPI
DebugPortInitialize (
  IN VOID                 *Context,
  IN DEBUG_PORT_CONTINUE  Function
  )
{
  RETURN_STATUS             Status;
  USB_DEBUG_PORT_HANDLE     Handle;

  if (Function == NULL && Context != NULL) {
    return (DEBUG_PORT_HANDLE *) Context;
  }

  ZeroMem(&Handle, sizeof (USB_DEBUG_PORT_HANDLE));

  Status = CalculateUsbDebugPortBar(&Handle.DebugPortOffset, &Handle.DebugPortBarNumber);
  if (RETURN_ERROR (Status)) {
    DEBUG ((EFI_D_ERROR, "USB Debug Port: the pci device pointed by PcdUsbEhciPciAddress is not EHCI host controller or does not support debug port capability!\n"));
    goto Exit;
  }

  Handle.EhciMemoryBase = 0xFFFFFC00 & PciRead32(PcdGet32(PcdUsbEhciPciAddress) + PCI_BASE_ADDRESSREG_OFFSET);

  if (Handle.EhciMemoryBase == 0) {
    //
    // Usb Debug Port MMIO Space Is Not Enabled. Assumption here that DebugPortBase is zero
    //
    PciWrite32(PcdGet32(PcdUsbEhciPciAddress) + PCI_BASE_ADDRESSREG_OFFSET, PcdGet32(PcdUsbEhciMemorySpaceBase));
    Handle.EhciMemoryBase = 0xFFFFFC00 & PciRead32(PcdGet32(PcdUsbEhciPciAddress) + PCI_BASE_ADDRESSREG_OFFSET);
  }

  Handle.UsbDebugPortMemoryBase = 0xFFFFFC00 & PciRead32(PcdGet32(PcdUsbEhciPciAddress) + PCI_BASE_ADDRESSREG_OFFSET + Handle.DebugPortBarNumber * 4);

  if (Handle.UsbDebugPortMemoryBase == 0) {
    //
    // Usb Debug Port MMIO Space Is Not Enabled. Assumption here that DebugPortBase is zero
    //
    PciWrite32(PcdGet32(PcdUsbEhciPciAddress) + PCI_BASE_ADDRESSREG_OFFSET + Handle.DebugPortBarNumber * 4, PcdGet32(PcdUsbDebugPortMemorySpaceBase));
    Handle.UsbDebugPortMemoryBase = 0xFFFFFC00 & PciRead32(PcdGet32(PcdUsbEhciPciAddress) + PCI_BASE_ADDRESSREG_OFFSET + Handle.DebugPortBarNumber * 4);
  }

  Status = InitializeUsbDebugHardware (&Handle);
  if (RETURN_ERROR(Status)) {
    DEBUG ((EFI_D_ERROR, "USB Debug Port: Initialization failed, please check if USB debug cable is plugged into EHCI debug port correctly!\n"));
    goto Exit;
  }

  //
  // Set debug port initialized successfully flag
  //
  Handle.Initialized = TRUE;

Exit:

  if (Function != NULL) {
    Function (Context, &Handle);
  } else {
    CopyMem(&mUsbDebugPortHandle, &Handle, sizeof (USB_DEBUG_PORT_HANDLE));
  }

  return (DEBUG_PORT_HANDLE)(UINTN)&mUsbDebugPortHandle;
}