[mirror_edk2.git] / SourceLevelDebugPkg / Library / DebugAgent / DxeDebugAgent / SerialIo.c

/** @file\r
  Install Serial IO Protocol that layers on top of a Debug Communication Library instance.\r
\r
  Copyright (c) 2012 - 2018, Intel Corporation. All rights reserved.<BR>\r
  SPDX-License-Identifier: BSD-2-Clause-Patent\r
\r
**/\r
\r
#include "DxeDebugAgentLib.h"\r
\r
//\r
// Serial I/O Protocol Interface definitions.\r
//\r
\r
/**\r
  Reset serial device.\r
\r
  @param[in] This           Pointer to EFI_SERIAL_IO_PROTOCOL.\r
\r
  @retval EFI_SUCCESS       Reset successfully.\r
\r
**/\r
EFI_STATUS\r
EFIAPI\r
SerialReset (\r
  IN EFI_SERIAL_IO_PROTOCOL  *This\r
  );\r
\r
/**\r
  Set new attributes to a serial device.\r
\r
  @param[in]  This                Pointer to EFI_SERIAL_IO_PROTOCOL.\r
  @param[in]  BaudRate            The baudrate of the serial device.\r
  @param[in]  ReceiveFifoDepth    The depth of receive FIFO buffer.\r
  @param[in]  Timeout             The request timeout for a single char.\r
  @param[in]  Parity              The type of parity used in serial device.\r
  @param[in]  DataBits            Number of databits used in serial device.\r
  @param[in]  StopBits            Number of stopbits used in serial device.\r
\r
  @retval EFI_SUCCESS             The new attributes were set.\r
  @retval EFI_INVALID_PARAMETER   One or more attributes have an unsupported value.\r
  @retval EFI_DEVICE_ERROR        The serial device is not functioning correctly (no return).\r
\r
**/\r
EFI_STATUS\r
EFIAPI\r
SerialSetAttributes (\r
  IN EFI_SERIAL_IO_PROTOCOL  *This,\r
  IN UINT64                  BaudRate,\r
  IN UINT32                  ReceiveFifoDepth,\r
  IN UINT32                  Timeout,\r
  IN EFI_PARITY_TYPE         Parity,\r
  IN UINT8                   DataBits,\r
  IN EFI_STOP_BITS_TYPE      StopBits\r
  );\r
\r
/**\r
  Set Control Bits.\r
\r
  @param[in] This            Pointer to EFI_SERIAL_IO_PROTOCOL.\r
  @param[in] Control         Control bits that can be settable.\r
\r
  @retval EFI_SUCCESS        New Control bits were set successfully.\r
  @retval EFI_UNSUPPORTED    The Control bits wanted to set are not supported.\r
\r
**/\r
EFI_STATUS\r
EFIAPI\r
SerialSetControl (\r
  IN EFI_SERIAL_IO_PROTOCOL  *This,\r
  IN UINT32                  Control\r
  );\r
\r
/**\r
  Get ControlBits.\r
\r
  @param[in]  This         Pointer to EFI_SERIAL_IO_PROTOCOL.\r
  @param[out] Control      Control signals of the serial device.\r
\r
  @retval EFI_SUCCESS  Get Control signals successfully.\r
\r
**/\r
EFI_STATUS\r
EFIAPI\r
SerialGetControl (\r
  IN EFI_SERIAL_IO_PROTOCOL  *This,\r
  OUT UINT32                 *Control\r
  );\r
\r
/**\r
  Write the specified number of bytes to serial device.\r
\r
  @param[in]      This       Pointer to EFI_SERIAL_IO_PROTOCOL.\r
  @param[in, out] BufferSize On input the size of Buffer, on output the amount of\r
                             data actually written.\r
  @param[in]      Buffer     The buffer of data to write.\r
\r
  @retval EFI_SUCCESS        The data were written successfully.\r
  @retval EFI_DEVICE_ERROR   The device reported an error.\r
  @retval EFI_TIMEOUT        The write operation was stopped due to timeout.\r
\r
**/\r
EFI_STATUS\r
EFIAPI\r
SerialWrite (\r
  IN EFI_SERIAL_IO_PROTOCOL  *This,\r
  IN OUT UINTN               *BufferSize,\r
  IN VOID                    *Buffer\r
  );\r
\r
/**\r
  Read the specified number of bytes from serial device.\r
\r
  @param[in] This            Pointer to EFI_SERIAL_IO_PROTOCOL.\r
  @param[in, out] BufferSize On input the size of Buffer, on output the amount of\r
                             data returned in buffer.\r
  @param[out] Buffer         The buffer to return the data into.\r
\r
  @retval EFI_SUCCESS        The data were read successfully.\r
  @retval EFI_DEVICE_ERROR   The device reported an error.\r
  @retval EFI_TIMEOUT        The read operation was stopped due to timeout.\r
\r
**/\r
EFI_STATUS\r
EFIAPI\r
SerialRead (\r
  IN EFI_SERIAL_IO_PROTOCOL  *This,\r
  IN OUT UINTN               *BufferSize,\r
  OUT VOID                   *Buffer\r
  );\r
\r
//\r
// Serial Driver Defaults\r
//\r
#define SERIAL_PORT_DEFAULT_RECEIVE_FIFO_DEPTH  1\r
#define SERIAL_PORT_DEFAULT_TIMEOUT             1000000\r
#define SERIAL_PORT_DEFAULT_CONTROL_MASK        0\r
#define SERIAL_PORT_LOOPBACK_BUFFER_FULL        BIT8\r
\r
//\r
// EFI_SERIAL_IO_MODE instance\r
//\r
EFI_SERIAL_IO_MODE  mSerialIoMode = {\r
  SERIAL_PORT_DEFAULT_CONTROL_MASK,\r
  SERIAL_PORT_DEFAULT_TIMEOUT,\r
  0,  // default BaudRate\r
  SERIAL_PORT_DEFAULT_RECEIVE_FIFO_DEPTH,\r
  0,  // default DataBits\r
  0,  // default Parity\r
  0   // default StopBits\r
};\r
\r
//\r
// EFI_SERIAL_IO_PROTOCOL instance\r
//\r
EFI_SERIAL_IO_PROTOCOL  mSerialIo = {\r
  SERIAL_IO_INTERFACE_REVISION,\r
  SerialReset,\r
  SerialSetAttributes,\r
  SerialSetControl,\r
  SerialGetControl,\r
  SerialWrite,\r
  SerialRead,\r
  &mSerialIoMode\r
};\r
\r
//\r
// Serial IO Device Path definition\r
//\r
typedef struct {\r
  VENDOR_DEVICE_PATH          VendorDevicePath;\r
  UART_DEVICE_PATH            UartDevicePath;\r
  EFI_DEVICE_PATH_PROTOCOL    EndDevicePath;\r
} SERIAL_IO_DEVICE_PATH;\r
\r
//\r
// Serial IO Device Patch instance\r
//\r
SERIAL_IO_DEVICE_PATH  mSerialIoDevicePath = {\r
  {\r
    {\r
      HARDWARE_DEVICE_PATH,\r
      HW_VENDOR_DP,\r
      {\r
        (UINT8)(sizeof (VENDOR_DEVICE_PATH)),\r
        (UINT8)((sizeof (VENDOR_DEVICE_PATH)) >> 8)\r
      }\r
    },\r
    EFI_DEBUG_AGENT_GUID,\r
  },\r
  {\r
    {\r
      MESSAGING_DEVICE_PATH,\r
      MSG_UART_DP,\r
      {\r
        (UINT8)(sizeof (UART_DEVICE_PATH)),\r
        (UINT8)((sizeof (UART_DEVICE_PATH)) >> 8)\r
      }\r
    },\r
    0,\r
    0,  // default BaudRate\r
    0,  // default DataBits\r
    0,  // default Parity\r
    0,  // default StopBits\r
  },\r
  {\r
    END_DEVICE_PATH_TYPE,\r
    END_ENTIRE_DEVICE_PATH_SUBTYPE,\r
    {\r
      END_DEVICE_PATH_LENGTH,\r
      0\r
    }\r
  }\r
};\r
\r
#define DEBGU_SERIAL_IO_FIFO_DEPTH  10\r
//\r
//  Data buffer for Terminal input character and Debug Symbols.\r
//  The depth is DEBGU_SERIAL_IO_FIFO_DEPTH.\r
//  Fields:\r
//      First   UINT8: The index of the first data in array Data[].\r
//      Last    UINT8: The index, which you can put a new data into array Data[].\r
//      Surplus UINT8: Identify how many data you can put into array Data[].\r
//      Data[]  UINT8: An array, which used to store data.\r
//\r
typedef struct {\r
  UINT8    First;\r
  UINT8    Last;\r
  UINT8    Surplus;\r
  UINT8    Data[DEBGU_SERIAL_IO_FIFO_DEPTH];\r
} DEBUG_SERIAL_FIFO;\r
\r
//\r
// Global Variables\r
//\r
EFI_HANDLE         mSerialIoHandle        = NULL;\r
UINTN              mLoopbackBuffer        = 0;\r
DEBUG_SERIAL_FIFO  mSerialFifoForTerminal = {\r
  0, 0, DEBGU_SERIAL_IO_FIFO_DEPTH, { 0 }\r
};\r
DEBUG_SERIAL_FIFO  mSerialFifoForDebug = {\r
  0, 0, DEBGU_SERIAL_IO_FIFO_DEPTH, { 0 }\r
};\r
\r
/**\r
  Detect whether specific FIFO is empty or not.\r
\r
  @param[in]  Fifo    A pointer to the Data Structure DEBUG_SERIAL_FIFO.\r
\r
  @return whether specific FIFO is empty or not.\r
\r
**/\r
BOOLEAN\r
IsDebugTermianlFifoEmpty (\r
  IN DEBUG_SERIAL_FIFO  *Fifo\r
  )\r
{\r
  if (Fifo->Surplus == DEBGU_SERIAL_IO_FIFO_DEPTH) {\r
    return TRUE;\r
  }\r
\r
  return FALSE;\r
}\r
\r
/**\r
  Detect whether specific FIFO is full or not.\r
\r
  @param[in] Fifo    A pointer to the Data Structure DEBUG_SERIAL_FIFO.\r
\r
  @return whether specific FIFO is full or not.\r
\r
**/\r
BOOLEAN\r
IsDebugTerminalFifoFull (\r
  IN DEBUG_SERIAL_FIFO  *Fifo\r
  )\r
\r
{\r
  if (Fifo->Surplus == 0) {\r
    return TRUE;\r
  }\r
\r
  return FALSE;\r
}\r
\r
/**\r
  Add data to specific FIFO.\r
\r
  @param[in] Fifo               A pointer to the Data Structure DEBUG_SERIAL_FIFO.\r
  @param[in] Data               The data added to FIFO.\r
\r
  @retval EFI_SUCCESS           Add data to specific FIFO successfully.\r
  @retval EFI_OUT_OF_RESOURCE   Failed to add data because FIFO is already full.\r
\r
**/\r
EFI_STATUS\r
DebugTerminalFifoAdd (\r
  IN DEBUG_SERIAL_FIFO  *Fifo,\r
  IN UINT8              Data\r
  )\r
\r
{\r
  //\r
  // if FIFO full can not add data\r
  //\r
  if (IsDebugTerminalFifoFull (Fifo)) {\r
    return EFI_OUT_OF_RESOURCES;\r
  }\r
\r
  //\r
  // FIFO is not full can add data\r
  //\r
  Fifo->Data[Fifo->Last] = Data;\r
  Fifo->Surplus--;\r
  Fifo->Last++;\r
  if (Fifo->Last == DEBGU_SERIAL_IO_FIFO_DEPTH) {\r
    Fifo->Last = 0;\r
  }\r
\r
  return EFI_SUCCESS;\r
}\r
\r
/**\r
  Remove data from specific FIFO.\r
\r
  @param[in]  Fifo              A pointer to the Data Structure DEBUG_SERIAL_FIFO.\r
  @param[out] Data              The data removed from FIFO.\r
\r
  @retval EFI_SUCCESS           Remove data from specific FIFO successfully.\r
  @retval EFI_OUT_OF_RESOURCE   Failed to remove data because FIFO is empty.\r
\r
**/\r
EFI_STATUS\r
DebugTerminalFifoRemove (\r
  IN  DEBUG_SERIAL_FIFO  *Fifo,\r
  OUT UINT8              *Data\r
  )\r
{\r
  //\r
  // if FIFO is empty, no data can remove\r
  //\r
  if (IsDebugTermianlFifoEmpty (Fifo)) {\r
    return EFI_OUT_OF_RESOURCES;\r
  }\r
\r
  //\r
  // FIFO is not empty, can remove data\r
  //\r
  *Data = Fifo->Data[Fifo->First];\r
  Fifo->Surplus++;\r
  Fifo->First++;\r
  if (Fifo->First == DEBGU_SERIAL_IO_FIFO_DEPTH) {\r
    Fifo->First = 0;\r
  }\r
\r
  return EFI_SUCCESS;\r
}\r
\r
/**\r
  Install EFI Serial IO protocol based on Debug Communication Library.\r
\r
**/\r
VOID\r
InstallSerialIo (\r
  VOID\r
  )\r
{\r
  EFI_STATUS  Status;\r
\r
  Status = gBS->InstallMultipleProtocolInterfaces (\r
                  &mSerialIoHandle,\r
                  &gEfiDevicePathProtocolGuid,\r
                  &mSerialIoDevicePath,\r
                  &gEfiSerialIoProtocolGuid,\r
                  &mSerialIo,\r
                  NULL\r
                  );\r
  if (EFI_ERROR (Status)) {\r
    DEBUG ((DEBUG_ERROR, "Debug Agent: Failed to install EFI Serial IO Protocol on Debug Port!\n"));\r
  }\r
}\r
\r
/**\r
  Reset serial device.\r
\r
  @param[in] This           Pointer to EFI_SERIAL_IO_PROTOCOL.\r
\r
  @retval EFI_SUCCESS       Reset successfully.\r
\r
**/\r
EFI_STATUS\r
EFIAPI\r
SerialReset (\r
  IN EFI_SERIAL_IO_PROTOCOL  *This\r
  )\r
{\r
  mSerialIoMode.ControlMask = SERIAL_PORT_DEFAULT_CONTROL_MASK;\r
  mLoopbackBuffer           = 0;\r
  //\r
  // Not reset serial device hardware indeed.\r
  //\r
  return EFI_SUCCESS;\r
}\r
\r
/**\r
  Set new attributes to a serial device.\r
\r
  @param[in]  This                Pointer to EFI_SERIAL_IO_PROTOCOL.\r
  @param[in]  BaudRate            The baudrate of the serial device.\r
  @param[in]  ReceiveFifoDepth    The depth of receive FIFO buffer.\r
  @param[in]  Timeout             The request timeout for a single char.\r
  @param[in]  Parity              The type of parity used in serial device.\r
  @param[in]  DataBits            Number of databits used in serial device.\r
  @param[in]  StopBits            Number of stopbits used in serial device.\r
\r
  @retval EFI_SUCCESS             The new attributes were set.\r
  @retval EFI_INVALID_PARAMETER   One or more attributes have an unsupported value.\r
  @retval EFI_DEVICE_ERROR        The serial device is not functioning correctly (no return).\r
\r
**/\r
EFI_STATUS\r
EFIAPI\r
SerialSetAttributes (\r
  IN EFI_SERIAL_IO_PROTOCOL  *This,\r
  IN UINT64                  BaudRate,\r
  IN UINT32                  ReceiveFifoDepth,\r
  IN UINT32                  Timeout,\r
  IN EFI_PARITY_TYPE         Parity,\r
  IN UINT8                   DataBits,\r
  IN EFI_STOP_BITS_TYPE      StopBits\r
  )\r
{\r
  //\r
  // The Debug Communication Library CAN NOT change communications parameters (if it has)\r
  // actually. Because it also has no any idea on what parameters are based on, we cannot\r
  // check the input parameters (like BaudRate, Parity, DataBits and StopBits).\r
  //\r
\r
  //\r
  // Update the Timeout value in the mode structure based on the request.\r
  // The Debug Communication Library can not support a timeout on writes, but the timeout on\r
  // reads can be provided by this module.\r
  //\r
  if (Timeout == 0) {\r
    mSerialIoMode.Timeout = SERIAL_PORT_DEFAULT_TIMEOUT;\r
  } else {\r
    mSerialIoMode.Timeout = Timeout;\r
  }\r
\r
  //\r
  // Update the ReceiveFifoDepth value in the mode structure based on the request.\r
  // This module assumes that the Debug Communication Library uses a FIFO depth of\r
  // SERIAL_PORT_DEFAULT_RECEIVE_FIFO_DEPTH.  The Debug Communication Library may actually be\r
  // using a larger FIFO, but there is no way to tell.\r
  //\r
  if ((ReceiveFifoDepth == 0) || (ReceiveFifoDepth >= SERIAL_PORT_DEFAULT_RECEIVE_FIFO_DEPTH)) {\r
    mSerialIoMode.ReceiveFifoDepth = SERIAL_PORT_DEFAULT_RECEIVE_FIFO_DEPTH;\r
  } else {\r
    return EFI_INVALID_PARAMETER;\r
  }\r
\r
  return EFI_SUCCESS;\r
}\r
\r
/**\r
  Set Control Bits.\r
\r
  @param[in] This            Pointer to EFI_SERIAL_IO_PROTOCOL.\r
  @param[in] Control         Control bits that can be settable.\r
\r
  @retval EFI_SUCCESS        New Control bits were set successfully.\r
  @retval EFI_UNSUPPORTED    The Control bits wanted to set are not supported.\r
\r
**/\r
EFI_STATUS\r
EFIAPI\r
SerialSetControl (\r
  IN EFI_SERIAL_IO_PROTOCOL  *This,\r
  IN UINT32                  Control\r
  )\r
{\r
  //\r
  // The only control bit supported by this module is software loopback.\r
  // If any other bit is set, then return an error\r
  //\r
  if ((Control & (~EFI_SERIAL_SOFTWARE_LOOPBACK_ENABLE)) != 0) {\r
    return EFI_UNSUPPORTED;\r
  }\r
\r
  mSerialIoMode.ControlMask = Control;\r
  return EFI_SUCCESS;\r
}\r
\r
/**\r
  Get ControlBits.\r
\r
  @param[in]  This         Pointer to EFI_SERIAL_IO_PROTOCOL.\r
  @param[out] Control      Control signals of the serial device.\r
\r
  @retval EFI_SUCCESS  Get Control signals successfully.\r
\r
**/\r
EFI_STATUS\r
EFIAPI\r
SerialGetControl (\r
  IN EFI_SERIAL_IO_PROTOCOL  *This,\r
  OUT UINT32                 *Control\r
  )\r
{\r
  DEBUG_PORT_HANDLE  Handle;\r
  BOOLEAN            DebugTimerInterruptState;\r
  EFI_TPL            Tpl;\r
\r
  //\r
  // Raise TPL to prevent recursion from EFI timer interrupts\r
  //\r
  Tpl = gBS->RaiseTPL (TPL_NOTIFY);\r
\r
  //\r
  // Save and disable Debug Timer interrupt to avoid it to access Debug Port\r
  //\r
  DebugTimerInterruptState = SaveAndSetDebugTimerInterrupt (FALSE);\r
  Handle                   = GetDebugPortHandle ();\r
\r
  //\r
  // Always assume the output buffer is empty and the Debug Communication Library can process\r
  // more write requests.\r
  //\r
  *Control = mSerialIoMode.ControlMask | EFI_SERIAL_OUTPUT_BUFFER_EMPTY;\r
\r
  //\r
  // Check to see if the Terminal FIFO is empty and\r
  // check to see if the input buffer in the Debug Communication Library is empty\r
  //\r
  if (!IsDebugTermianlFifoEmpty (&mSerialFifoForTerminal) || DebugPortPollBuffer (Handle)) {\r
    *Control &= ~EFI_SERIAL_INPUT_BUFFER_EMPTY;\r
  }\r
\r
  //\r
  // Restore Debug Timer interrupt\r
  //\r
  SaveAndSetDebugTimerInterrupt (DebugTimerInterruptState);\r
\r
  //\r
  // Restore to original TPL\r
  //\r
  gBS->RestoreTPL (Tpl);\r
\r
  return EFI_SUCCESS;\r
}\r
\r
/**\r
  Write the specified number of bytes to serial device.\r
\r
  @param[in]      This       Pointer to EFI_SERIAL_IO_PROTOCOL.\r
  @param[in, out] BufferSize On input the size of Buffer, on output the amount of\r
                             data actually written.\r
  @param[in]      Buffer     The buffer of data to write.\r
\r
  @retval EFI_SUCCESS        The data were written successfully.\r
  @retval EFI_DEVICE_ERROR   The device reported an error.\r
  @retval EFI_TIMEOUT        The write operation was stopped due to timeout.\r
\r
**/\r
EFI_STATUS\r
EFIAPI\r
SerialWrite (\r
  IN EFI_SERIAL_IO_PROTOCOL  *This,\r
  IN OUT UINTN               *BufferSize,\r
  IN VOID                    *Buffer\r
  )\r
{\r
  DEBUG_PORT_HANDLE  Handle;\r
  BOOLEAN            DebugTimerInterruptState;\r
  EFI_TPL            Tpl;\r
\r
  //\r
  // Raise TPL to prevent recursion from EFI timer interrupts\r
  //\r
  Tpl = gBS->RaiseTPL (TPL_NOTIFY);\r
\r
  //\r
  // Save and disable Debug Timer interrupt to avoid it to access Debug Port\r
  //\r
  DebugTimerInterruptState = SaveAndSetDebugTimerInterrupt (FALSE);\r
  Handle                   = GetDebugPortHandle ();\r
\r
  if ((mSerialIoMode.ControlMask & EFI_SERIAL_SOFTWARE_LOOPBACK_ENABLE) != 0) {\r
    if (*BufferSize == 0) {\r
      return EFI_SUCCESS;\r
    }\r
\r
    if ((mLoopbackBuffer & SERIAL_PORT_LOOPBACK_BUFFER_FULL) != 0) {\r
      *BufferSize = 0;\r
      return EFI_TIMEOUT;\r
    }\r
\r
    mLoopbackBuffer = SERIAL_PORT_LOOPBACK_BUFFER_FULL | *(UINT8 *)Buffer;\r
    *BufferSize     = 1;\r
  } else {\r
    *BufferSize = DebugPortWriteBuffer (Handle, Buffer, *BufferSize);\r
  }\r
\r
  //\r
  // Restore Debug Timer interrupt\r
  //\r
  SaveAndSetDebugTimerInterrupt (DebugTimerInterruptState);\r
\r
  //\r
  // Restore to original TPL\r
  //\r
  gBS->RestoreTPL (Tpl);\r
\r
  return EFI_SUCCESS;\r
}\r
\r
/**\r
  Read the specified number of bytes from serial device.\r
\r
  @param[in] This            Pointer to EFI_SERIAL_IO_PROTOCOL.\r
  @param[in, out] BufferSize On input the size of Buffer, on output the amount of\r
                             data returned in buffer.\r
  @param[out] Buffer         The buffer to return the data into.\r
\r
  @retval EFI_SUCCESS        The data were read successfully.\r
  @retval EFI_DEVICE_ERROR   The device reported an error.\r
  @retval EFI_TIMEOUT        The read operation was stopped due to timeout.\r
\r
**/\r
EFI_STATUS\r
EFIAPI\r
SerialRead (\r
  IN EFI_SERIAL_IO_PROTOCOL  *This,\r
  IN OUT UINTN               *BufferSize,\r
  OUT VOID                   *Buffer\r
  )\r
{\r
  EFI_STATUS           Status;\r
  UINTN                Index;\r
  UINT8                *Uint8Buffer;\r
  BOOLEAN              DebugTimerInterruptState;\r
  EFI_TPL              Tpl;\r
  DEBUG_PORT_HANDLE    Handle;\r
  DEBUG_PACKET_HEADER  DebugHeader;\r
  UINT8                *Data8;\r
\r
  //\r
  // Raise TPL to prevent recursion from EFI timer interrupts\r
  //\r
  Tpl = gBS->RaiseTPL (TPL_NOTIFY);\r
\r
  //\r
  // Save and disable Debug Timer interrupt to avoid it to access Debug Port\r
  //\r
  DebugTimerInterruptState = SaveAndSetDebugTimerInterrupt (FALSE);\r
  Handle                   = GetDebugPortHandle ();\r
\r
  Data8       = (UINT8 *)&DebugHeader;\r
  Uint8Buffer = (UINT8 *)Buffer;\r
  if ((mSerialIoMode.ControlMask & EFI_SERIAL_SOFTWARE_LOOPBACK_ENABLE) != 0) {\r
    if ((mLoopbackBuffer & SERIAL_PORT_LOOPBACK_BUFFER_FULL) == 0) {\r
      return EFI_TIMEOUT;\r
    }\r
\r
    *Uint8Buffer    = (UINT8)(mLoopbackBuffer & 0xff);\r
    mLoopbackBuffer = 0;\r
    *BufferSize     = 1;\r
  } else {\r
    for (Index = 0; Index < *BufferSize; Index++) {\r
      //\r
      // Read input character from terminal FIFO firstly\r
      //\r
      Status = DebugTerminalFifoRemove (&mSerialFifoForTerminal, Data8);\r
      if (Status == EFI_SUCCESS) {\r
        *Uint8Buffer = *Data8;\r
        Uint8Buffer++;\r
        continue;\r
      }\r
\r
      //\r
      // Read the input character from Debug Port\r
      //\r
      if (!DebugPortPollBuffer (Handle)) {\r
        break;\r
      }\r
\r
      DebugAgentReadBuffer (Handle, Data8, 1, 0);\r
\r
      if (*Data8 == DEBUG_STARTING_SYMBOL_ATTACH) {\r
        //\r
        // Add the debug symbol into Debug FIFO\r
        //\r
        DebugAgentMsgPrint (DEBUG_AGENT_INFO, "Terminal Timer attach symbol received %x", *Data8);\r
        DebugTerminalFifoAdd (&mSerialFifoForDebug, *Data8);\r
      } else if (*Data8 == DEBUG_STARTING_SYMBOL_NORMAL) {\r
        Status = ReadRemainingBreakPacket (Handle, &DebugHeader);\r
        if (Status == EFI_SUCCESS) {\r
          DebugAgentMsgPrint (DEBUG_AGENT_INFO, "Terminal Timer break symbol received %x", DebugHeader.Command);\r
          DebugTerminalFifoAdd (&mSerialFifoForDebug, DebugHeader.Command);\r
        }\r
\r
        if (Status == EFI_TIMEOUT) {\r
          continue;\r
        }\r
      } else {\r
        *Uint8Buffer = *Data8;\r
        Uint8Buffer++;\r
      }\r
    }\r
\r
    *BufferSize = (UINTN)Uint8Buffer - (UINTN)Buffer;\r
  }\r
\r
  //\r
  // Restore Debug Timer interrupt\r
  //\r
  SaveAndSetDebugTimerInterrupt (DebugTimerInterruptState);\r
\r
  //\r
  // Restore to original TPL\r
  //\r
  gBS->RestoreTPL (Tpl);\r
\r
  return EFI_SUCCESS;\r
}\r
\r
/**\r
  Read the Attach/Break-in symbols from the debug port.\r
\r
  @param[in]  Handle         Pointer to Debug Port handle.\r
  @param[out] BreakSymbol    Returned break symbol.\r
\r
  @retval EFI_SUCCESS        Read the symbol in BreakSymbol.\r
  @retval EFI_NOT_FOUND      No read the break symbol.\r
\r
**/\r
EFI_STATUS\r
DebugReadBreakFromDebugPort (\r
  IN  DEBUG_PORT_HANDLE  Handle,\r
  OUT UINT8              *BreakSymbol\r
  )\r
{\r
  EFI_STATUS           Status;\r
  DEBUG_PACKET_HEADER  DebugHeader;\r
  UINT8                *Data8;\r
\r
  *BreakSymbol = 0;\r
  //\r
  // If Debug Port buffer has data, read it till it was break symbol or Debug Port buffer empty.\r
  //\r
  Data8 = (UINT8 *)&DebugHeader;\r
  while (TRUE) {\r
    //\r
    // If start symbol is not received\r
    //\r
    if (!DebugPortPollBuffer (Handle)) {\r
      //\r
      // If no data in Debug Port, exit\r
      //\r
      break;\r
    }\r
\r
    //\r
    // Try to read the start symbol\r
    //\r
    DebugAgentReadBuffer (Handle, Data8, 1, 0);\r
    if (*Data8 == DEBUG_STARTING_SYMBOL_ATTACH) {\r
      DebugAgentMsgPrint (DEBUG_AGENT_INFO, "Debug Timer attach symbol received %x", *Data8);\r
      *BreakSymbol = *Data8;\r
      return EFI_SUCCESS;\r
    }\r
\r
    if (*Data8 == DEBUG_STARTING_SYMBOL_NORMAL) {\r
      Status = ReadRemainingBreakPacket (Handle, &DebugHeader);\r
      if (Status == EFI_SUCCESS) {\r
        DebugAgentMsgPrint (DEBUG_AGENT_INFO, "Debug Timer break symbol received %x", DebugHeader.Command);\r
        *BreakSymbol = DebugHeader.Command;\r
        return EFI_SUCCESS;\r
      }\r
\r
      if (Status == EFI_TIMEOUT) {\r
        break;\r
      }\r
    } else {\r
      //\r
      // Add to Terminal FIFO\r
      //\r
      DebugTerminalFifoAdd (&mSerialFifoForTerminal, *Data8);\r
    }\r
  }\r
\r
  return EFI_NOT_FOUND;\r
}\r
\r
/**\r
  Read the Attach/Break-in symbols.\r
\r
  @param[in]  Handle         Pointer to Debug Port handle.\r
  @param[out] BreakSymbol    Returned break symbol.\r
\r
  @retval EFI_SUCCESS        Read the symbol in BreakSymbol.\r
  @retval EFI_NOT_FOUND      No read the break symbol.\r
\r
**/\r
EFI_STATUS\r
DebugReadBreakSymbol (\r
  IN  DEBUG_PORT_HANDLE  Handle,\r
  OUT UINT8              *BreakSymbol\r
  )\r
{\r
  EFI_STATUS  Status;\r
  UINT8       Data8;\r
\r
  //\r
  // Read break symbol from debug FIFO firstly\r
  //\r
  Status = DebugTerminalFifoRemove (&mSerialFifoForDebug, &Data8);\r
  if (Status == EFI_SUCCESS) {\r
    *BreakSymbol = Data8;\r
    return EFI_SUCCESS;\r
  } else {\r
    //\r
    // Read Break symbol from debug port\r
    //\r
    return DebugReadBreakFromDebugPort (Handle, BreakSymbol);\r
  }\r
}\r