/**@file

Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent

Module Name:

  WinNtSerialIo.c

Abstract:

  Our DriverBinding member functions operate on the handles
  created by the NT Bus driver.

  Handle(1) - WinNtIo - DevicePath(1)

  If a serial port is added to the system this driver creates a new handle.
  The new handle is required, since the serial device must add an UART device
  pathnode.

  Handle(2) - SerialIo - DevicePath(1)\UART

  The driver then adds a gEfiWinNtSerialPortGuid as a protocol to Handle(1).
  The instance data for this protocol is the private data used to create
  Handle(2).

  Handle(1) - WinNtIo - DevicePath(1) - WinNtSerialPort

  If the driver is unloaded Handle(2) is removed from the system and
  gEfiWinNtSerialPortGuid is removed from Handle(1).

  Note: Handle(1) is any handle created by the Win NT Bus driver that is passed
  into the DriverBinding member functions of this driver. This driver requires
  a Handle(1) to contain a WinNtIo protocol, a DevicePath protocol, and
  the TypeGuid in the WinNtIo must be gEfiWinNtSerialPortGuid.

  If Handle(1) contains a gEfiWinNtSerialPortGuid protocol then the driver is
  loaded on the device.

**/

#include "WinNtSerialIo.h"

EFI_DRIVER_BINDING_PROTOCOL gWinNtSerialIoDriverBinding = {
  WinNtSerialIoDriverBindingSupported,
  WinNtSerialIoDriverBindingStart,
  WinNtSerialIoDriverBindingStop,
  0xa,
  NULL,
  NULL
};

//
// List of supported baud rate
//
UINT64 mBaudRateCurrentSupport[] = {50, 75, 110, 134, 150, 300, 600, 1200, 1800, 2000, 2400, 3600, 4800, 7200, 9600, 19200, 38400, 57600, 115200, SERIAL_PORT_MAX_BAUD_RATE + 1};

/**
  Check the device path node whether it's the Flow Control node or not.

  @param[in] FlowControl    The device path node to be checked.
  
  @retval TRUE              It's the Flow Control node.
  @retval FALSE             It's not.

**/
BOOLEAN
IsUartFlowControlNode (
  IN UART_FLOW_CONTROL_DEVICE_PATH *FlowControl
  )
{
  return (BOOLEAN) (
           (DevicePathType (FlowControl) == MESSAGING_DEVICE_PATH) &&
           (DevicePathSubType (FlowControl) == MSG_VENDOR_DP) &&
           (CompareGuid (&FlowControl->Guid, &gEfiUartDevicePathGuid))
           );
}

/**
  Check the device path node whether it contains Flow Control node or not.

  @param[in] DevicePath     The device path to be checked.
  
  @retval TRUE              It contains the Flow Control node.
  @retval FALSE             It doesn't.

**/
BOOLEAN
ContainsFlowControl (
  IN EFI_DEVICE_PATH_PROTOCOL      *DevicePath
  )
{
  while (!IsDevicePathEnd (DevicePath)) {
    if (IsUartFlowControlNode ((UART_FLOW_CONTROL_DEVICE_PATH *) DevicePath)) {
      return TRUE;
    }
    DevicePath = NextDevicePathNode (DevicePath);
  }

  return FALSE;
}

/**
  The user Entry Point for module WinNtSerialIo. The user code starts with this function.

  @param[in] ImageHandle    The firmware allocated handle for the EFI image.  
  @param[in] SystemTable    A pointer to the EFI System Table.
  
  @retval EFI_SUCCESS       The entry point is executed successfully.
  @retval other             Some error occurs when executing this entry point.

**/
EFI_STATUS
EFIAPI
InitializeWinNtSerialIo(
  IN EFI_HANDLE           ImageHandle,
  IN EFI_SYSTEM_TABLE     *SystemTable
  )
{
  EFI_STATUS              Status;

  //
  // Install driver model protocol(s).
  //
  Status = EfiLibInstallDriverBindingComponentName2 (
             ImageHandle,
             SystemTable,
             &gWinNtSerialIoDriverBinding,
             ImageHandle,
             &gWinNtSerialIoComponentName,
             &gWinNtSerialIoComponentName2
             );
  ASSERT_EFI_ERROR (Status);


  return Status;
}

EFI_STATUS
EFIAPI
WinNtSerialIoDriverBindingSupported (
  IN  EFI_DRIVER_BINDING_PROTOCOL   *This,
  IN  EFI_HANDLE                    Handle,
  IN  EFI_DEVICE_PATH_PROTOCOL      *RemainingDevicePath
  )
/*++

Routine Description:

Arguments:

Returns:

  None

--*/
// TODO:    This - add argument and description to function comment
// TODO:    Handle - add argument and description to function comment
// TODO:    RemainingDevicePath - add argument and description to function comment
// TODO:    EFI_SUCCESS - add return value to function comment
// TODO:    EFI_SUCCESS - add return value to function comment
{
  EFI_STATUS                          Status;
  EFI_DEVICE_PATH_PROTOCOL            *ParentDevicePath;
  EFI_WIN_NT_IO_PROTOCOL              *WinNtIo;
  UART_DEVICE_PATH                    *UartNode;
  EFI_DEVICE_PATH_PROTOCOL            *DevicePath;
  UART_FLOW_CONTROL_DEVICE_PATH       *FlowControlNode;
  EFI_OPEN_PROTOCOL_INFORMATION_ENTRY *OpenInfoBuffer;
  UINTN                               EntryCount;
  UINTN                               Index;
  BOOLEAN                             RemainingDevicePathContainsFlowControl; 

  //
  // Check RemainingDevicePath validation
  //
  if (RemainingDevicePath != NULL) {
    //
    // Check if RemainingDevicePath is the End of Device Path Node, 
    // if yes, go on checking other conditions
    //
    if (!IsDevicePathEnd (RemainingDevicePath)) {
      //
      // If RemainingDevicePath isn't the End of Device Path Node,
      // check its validation
      //
      Status = EFI_UNSUPPORTED;

      UartNode  = (UART_DEVICE_PATH *) RemainingDevicePath;
      if (UartNode->Header.Type != MESSAGING_DEVICE_PATH ||
          UartNode->Header.SubType != MSG_UART_DP ||
          DevicePathNodeLength((EFI_DEVICE_PATH_PROTOCOL *)UartNode) != sizeof(UART_DEVICE_PATH)) {
        goto Error;
      }
      if ( UartNode->BaudRate > SERIAL_PORT_MAX_BAUD_RATE) {
        goto Error;
      }
      if (UartNode->Parity < NoParity || UartNode->Parity > SpaceParity) {
        goto Error;
      }
      if (UartNode->DataBits < 5 || UartNode->DataBits > 8) {
        goto Error;
      }
      if (UartNode->StopBits < OneStopBit || UartNode->StopBits > TwoStopBits) {
        goto Error;
      }
      if ((UartNode->DataBits == 5) && (UartNode->StopBits == TwoStopBits)) {
        goto Error;
      }
      if ((UartNode->DataBits >= 6) && (UartNode->DataBits <= 8) && (UartNode->StopBits == OneFiveStopBits)) {
        goto Error;
      }

      FlowControlNode = (UART_FLOW_CONTROL_DEVICE_PATH *) NextDevicePathNode (UartNode);
      if (IsUartFlowControlNode (FlowControlNode)) {
        //
        // If the second node is Flow Control Node,
        //   return error when it request other than hardware flow control.
        //
        if ((FlowControlNode->FlowControlMap & ~UART_FLOW_CONTROL_HARDWARE) != 0) {
          goto Error;
        }
      }
    }
  }

  //
  // Open the IO Abstraction(s) needed to perform the supported test
  //
  Status = gBS->OpenProtocol (
                  Handle,
                  &gEfiWinNtIoProtocolGuid,
                  (VOID **) &WinNtIo,
                  This->DriverBindingHandle,
                  Handle,
                  EFI_OPEN_PROTOCOL_BY_DRIVER
                  );
  if (Status == EFI_ALREADY_STARTED) {
    if (RemainingDevicePath == NULL || IsDevicePathEnd (RemainingDevicePath)) {
      //
      // If RemainingDevicePath is NULL or is the End of Device Path Node
      //
      return EFI_SUCCESS;
    }
    //
    // When the driver has produced device path with flow control node but RemainingDevicePath only contains UART node,
    //   return unsupported, and vice versa.
    //
    Status = gBS->OpenProtocolInformation (
                    Handle,
                    &gEfiWinNtIoProtocolGuid,
                    &OpenInfoBuffer,
                    &EntryCount
                    );
    if (EFI_ERROR (Status)) {
      return Status;
    }

    //
    // See if RemainingDevicePath has a Flow Control device path node
    //
    RemainingDevicePathContainsFlowControl = ContainsFlowControl (RemainingDevicePath);
    
    for (Index = 0; Index < EntryCount; Index++) {
      if ((OpenInfoBuffer[Index].Attributes & EFI_OPEN_PROTOCOL_BY_CHILD_CONTROLLER) != 0) {
        Status = gBS->OpenProtocol (
                        OpenInfoBuffer[Index].ControllerHandle,
                        &gEfiDevicePathProtocolGuid,
                        (VOID **) &DevicePath,
                        This->DriverBindingHandle,
                        Handle,
                        EFI_OPEN_PROTOCOL_GET_PROTOCOL
                        );
        if (!EFI_ERROR (Status)) {
          if (RemainingDevicePathContainsFlowControl ^ ContainsFlowControl (DevicePath)) {
            Status = EFI_UNSUPPORTED;
          }
        }
        break;
      }
    }
    FreePool (OpenInfoBuffer);
    return Status;
  }

  if (EFI_ERROR (Status)) {
    return Status;
  }

  //
  // Close the I/O Abstraction(s) used to perform the supported test
  //
  gBS->CloseProtocol (
        Handle,
        &gEfiWinNtIoProtocolGuid,
        This->DriverBindingHandle,
        Handle
        );

  //
  // Open the EFI Device Path protocol needed to perform the supported test
  //
  Status = gBS->OpenProtocol (
                  Handle,
                  &gEfiDevicePathProtocolGuid,
                  (VOID **) &ParentDevicePath,
                  This->DriverBindingHandle,
                  Handle,
                  EFI_OPEN_PROTOCOL_BY_DRIVER
                  );
  if (Status == EFI_ALREADY_STARTED) {
    return EFI_SUCCESS;
  }

  if (EFI_ERROR (Status)) {
    return Status;
  }

  //
  // Close protocol, don't use device path protocol in the Support() function
  //
  gBS->CloseProtocol (
        Handle,
        &gEfiDevicePathProtocolGuid,
        This->DriverBindingHandle,
        Handle
        );

  //
  // Make sure that the WinNt Thunk Protocol is valid
  //
  if (WinNtIo->WinNtThunk->Signature != EFI_WIN_NT_THUNK_PROTOCOL_SIGNATURE) {
    Status = EFI_UNSUPPORTED;
    goto Error;
  }

  //
  // Check the GUID to see if this is a handle type the driver supports
  //
  if (!CompareGuid (WinNtIo->TypeGuid, &gEfiWinNtSerialPortGuid)) {
    Status = EFI_UNSUPPORTED;
    goto Error;
  }

  return EFI_SUCCESS;

Error:
  return Status;
}

EFI_STATUS
EFIAPI
WinNtSerialIoDriverBindingStart (
  IN  EFI_DRIVER_BINDING_PROTOCOL   *This,
  IN  EFI_HANDLE                    Handle,
  IN  EFI_DEVICE_PATH_PROTOCOL      *RemainingDevicePath
  )
/*++

Routine Description:

Arguments:

Returns:

  None

--*/
// TODO:    This - add argument and description to function comment
// TODO:    Handle - add argument and description to function comment
// TODO:    RemainingDevicePath - add argument and description to function comment
// TODO:    EFI_SUCCESS - add return value to function comment
// TODO:    EFI_SUCCESS - add return value to function comment
{
  EFI_STATUS                          Status;
  EFI_WIN_NT_IO_PROTOCOL              *WinNtIo;
  WIN_NT_SERIAL_IO_PRIVATE_DATA       *Private;
  HANDLE                              NtHandle;
  UART_DEVICE_PATH                    UartNode;
  EFI_DEVICE_PATH_PROTOCOL            *ParentDevicePath;
  EFI_OPEN_PROTOCOL_INFORMATION_ENTRY *OpenInfoBuffer;
  UINTN                               EntryCount;
  UINTN                               Index;
  EFI_SERIAL_IO_PROTOCOL              *SerialIo;
  UART_DEVICE_PATH                    *Uart;
  UINT32                              FlowControlMap;
  UART_FLOW_CONTROL_DEVICE_PATH       *FlowControl;
  EFI_DEVICE_PATH_PROTOCOL            *TempDevicePath;
  UINT32                              Control;

  Private   = NULL;
  NtHandle  = INVALID_HANDLE_VALUE;

  //
  // Get the Parent Device Path
  //
  Status = gBS->OpenProtocol (
                  Handle,
                  &gEfiDevicePathProtocolGuid,
                  (VOID **) &ParentDevicePath,
                  This->DriverBindingHandle,
                  Handle,
                  EFI_OPEN_PROTOCOL_BY_DRIVER
                  );
  if (EFI_ERROR (Status) && Status != EFI_ALREADY_STARTED) {
    return Status;
  }

  //
  // Grab the IO abstraction we need to get any work done
  //
  Status = gBS->OpenProtocol (
                  Handle,
                  &gEfiWinNtIoProtocolGuid,
                  (VOID **) &WinNtIo,
                  This->DriverBindingHandle,
                  Handle,
                  EFI_OPEN_PROTOCOL_BY_DRIVER
                  );
  if (EFI_ERROR (Status) && Status != EFI_ALREADY_STARTED) {
    gBS->CloseProtocol (
          Handle,
          &gEfiDevicePathProtocolGuid,
          This->DriverBindingHandle,
          Handle
          );
    return Status;
  }

  if (Status == EFI_ALREADY_STARTED) {

    if (RemainingDevicePath == NULL || IsDevicePathEnd (RemainingDevicePath)) {
      //
      // If RemainingDevicePath is NULL or is the End of Device Path Node
      //
      return EFI_SUCCESS;
    }

    //
    // Make sure a child handle does not already exist.  This driver can only
    // produce one child per serial port.
    //
    Status = gBS->OpenProtocolInformation (
                    Handle,
                    &gEfiWinNtIoProtocolGuid,
                    &OpenInfoBuffer,
                    &EntryCount
                    );
    if (EFI_ERROR (Status)) {
      return Status;
    }

    Status = EFI_ALREADY_STARTED;
    for (Index = 0; Index < EntryCount; Index++) {
      if ((OpenInfoBuffer[Index].Attributes & EFI_OPEN_PROTOCOL_BY_CHILD_CONTROLLER) != 0) {
        Status = gBS->OpenProtocol (
                        OpenInfoBuffer[Index].ControllerHandle,
                        &gEfiSerialIoProtocolGuid,
                        (VOID **) &SerialIo,
                        This->DriverBindingHandle,
                        Handle,
                        EFI_OPEN_PROTOCOL_GET_PROTOCOL
                        );
        if (!EFI_ERROR (Status)) {
          Uart   = (UART_DEVICE_PATH *) RemainingDevicePath;
          Status = SerialIo->SetAttributes (
                               SerialIo,
                               Uart->BaudRate,
                               SerialIo->Mode->ReceiveFifoDepth,
                               SerialIo->Mode->Timeout,
                               (EFI_PARITY_TYPE) Uart->Parity,
                               Uart->DataBits,
                               (EFI_STOP_BITS_TYPE) Uart->StopBits
                               );
          FlowControl = (UART_FLOW_CONTROL_DEVICE_PATH *) NextDevicePathNode (Uart);
          if (!EFI_ERROR (Status) && IsUartFlowControlNode (FlowControl)) {
            Status = SerialIo->GetControl (SerialIo, &Control);
            if (!EFI_ERROR (Status)) {
              if (FlowControl->FlowControlMap == UART_FLOW_CONTROL_HARDWARE) {
                Control |= EFI_SERIAL_HARDWARE_FLOW_CONTROL_ENABLE;
              } else {
                Control &= ~EFI_SERIAL_HARDWARE_FLOW_CONTROL_ENABLE;
              }
              //
              // Clear the bits that are not allowed to pass to SetControl
              //
              Control &= (EFI_SERIAL_REQUEST_TO_SEND | EFI_SERIAL_DATA_TERMINAL_READY |
                          EFI_SERIAL_HARDWARE_LOOPBACK_ENABLE | EFI_SERIAL_SOFTWARE_LOOPBACK_ENABLE | 
                          EFI_SERIAL_HARDWARE_FLOW_CONTROL_ENABLE);
              Status = SerialIo->SetControl (SerialIo, Control);
            }
          }
        }
        break;
      }
    }

    FreePool (OpenInfoBuffer);
    return Status;
  }

  FlowControl    = NULL;
  FlowControlMap = 0;
  if (RemainingDevicePath == NULL) {
    //
    // Build the device path by appending the UART node to the ParentDevicePath
    // from the WinNtIo handle. The Uart setings are zero here, since
    // SetAttribute() will update them to match the default setings.
    //
    ZeroMem (&UartNode, sizeof (UART_DEVICE_PATH));
    UartNode.Header.Type     = MESSAGING_DEVICE_PATH;
    UartNode.Header.SubType  = MSG_UART_DP;
    SetDevicePathNodeLength ((EFI_DEVICE_PATH_PROTOCOL *) &UartNode, sizeof (UART_DEVICE_PATH));

  } else if (!IsDevicePathEnd (RemainingDevicePath)) {
    //
    // If RemainingDevicePath isn't the End of Device Path Node, 
    // only scan the specified device by RemainingDevicePath
    //
    //
    // Match the configuration of the RemainingDevicePath. IsHandleSupported()
    // already checked to make sure the RemainingDevicePath contains settings
    // that we can support.
    //
    CopyMem (&UartNode, RemainingDevicePath, sizeof (UART_DEVICE_PATH));
    FlowControl = (UART_FLOW_CONTROL_DEVICE_PATH *) NextDevicePathNode (RemainingDevicePath);
    if (IsUartFlowControlNode (FlowControl)) {
      FlowControlMap = FlowControl->FlowControlMap;
    } else {
      FlowControl    = NULL;
    }

  } else {
    //
    // If RemainingDevicePath is the End of Device Path Node,
    // skip enumerate any device and return EFI_SUCESSS
    // 
    return EFI_SUCCESS;
  }

  //
  // Check to see if we can access the hardware device. If it's Open in NT we
  // will not get access.
  //
  NtHandle = WinNtIo->WinNtThunk->CreateFile (
                                    WinNtIo->EnvString,
                                    GENERIC_READ | GENERIC_WRITE,
                                    0,
                                    NULL,
                                    OPEN_EXISTING,
                                    0,
                                    NULL
                                    );
  if (NtHandle == INVALID_HANDLE_VALUE) {
    Status = EFI_DEVICE_ERROR;
    goto Error;
  }

  //
  // Construct Private data
  //
  Private = AllocatePool (sizeof (WIN_NT_SERIAL_IO_PRIVATE_DATA));
  if (Private == NULL) {
    goto Error;
  }

  //
  // This signature must be valid before any member function is called
  //
  Private->Signature              = WIN_NT_SERIAL_IO_PRIVATE_DATA_SIGNATURE;
  Private->NtHandle               = NtHandle;
  Private->ControllerHandle       = Handle;
  Private->Handle                 = NULL;
  Private->WinNtThunk             = WinNtIo->WinNtThunk;
  Private->ParentDevicePath       = ParentDevicePath;
  Private->ControllerNameTable    = NULL;

  Private->SoftwareLoopbackEnable = FALSE;
  Private->HardwareLoopbackEnable = FALSE;
  Private->HardwareFlowControl    = (BOOLEAN) (FlowControlMap == UART_FLOW_CONTROL_HARDWARE);
  Private->Fifo.First             = 0;
  Private->Fifo.Last              = 0;
  Private->Fifo.Surplus           = SERIAL_MAX_BUFFER_SIZE;

  CopyMem (&Private->UartDevicePath, &UartNode, sizeof (UART_DEVICE_PATH));

  AddUnicodeString2 (
    "eng",
    gWinNtSerialIoComponentName.SupportedLanguages,
    &Private->ControllerNameTable,
    WinNtIo->EnvString,
    TRUE
    );
  AddUnicodeString2 (
    "en",
    gWinNtSerialIoComponentName2.SupportedLanguages,
    &Private->ControllerNameTable,
    WinNtIo->EnvString,
    FALSE
    );


  Private->SerialIo.Revision      = SERIAL_IO_INTERFACE_REVISION;
  Private->SerialIo.Reset         = WinNtSerialIoReset;
  Private->SerialIo.SetAttributes = WinNtSerialIoSetAttributes;
  Private->SerialIo.SetControl    = WinNtSerialIoSetControl;
  Private->SerialIo.GetControl    = WinNtSerialIoGetControl;
  Private->SerialIo.Write         = WinNtSerialIoWrite;
  Private->SerialIo.Read          = WinNtSerialIoRead;
  Private->SerialIo.Mode          = &Private->SerialIoMode;

  //
  // Build the device path by appending the UART node to the ParentDevicePath
  // from the WinNtIo handle. The Uart setings are zero here, since
  // SetAttribute() will update them to match the current setings.
  //
  Private->DevicePath = AppendDevicePathNode (
                          ParentDevicePath,
                          (EFI_DEVICE_PATH_PROTOCOL *) &Private->UartDevicePath
                          );
  //
  // Only produce the FlowControl node when remaining device path has it
  //
  if (FlowControl != NULL) {
    TempDevicePath = Private->DevicePath;
    if (TempDevicePath != NULL) {
      Private->DevicePath = AppendDevicePathNode (
                              TempDevicePath,
                              (EFI_DEVICE_PATH_PROTOCOL *) FlowControl
                              );
      FreePool (TempDevicePath);
    }
  }
  if (Private->DevicePath == NULL) {
    Status = EFI_OUT_OF_RESOURCES;
    goto Error;
  }

  //
  // Fill in Serial I/O Mode structure based on either the RemainingDevicePath or defaults.
  //
  Private->SerialIoMode.ControlMask       = SERIAL_CONTROL_MASK;
  Private->SerialIoMode.Timeout           = SERIAL_TIMEOUT_DEFAULT;
  Private->SerialIoMode.BaudRate          = Private->UartDevicePath.BaudRate;
  Private->SerialIoMode.ReceiveFifoDepth  = SERIAL_FIFO_DEFAULT;
  Private->SerialIoMode.DataBits          = Private->UartDevicePath.DataBits;
  Private->SerialIoMode.Parity            = Private->UartDevicePath.Parity;
  Private->SerialIoMode.StopBits          = Private->UartDevicePath.StopBits;

  //
  // Issue a reset to initialize the COM port
  //
  Status = Private->SerialIo.Reset (&Private->SerialIo);
  if (EFI_ERROR (Status)) {
    goto Error;
  }

  //
  // Create new child handle
  //
  Status = gBS->InstallMultipleProtocolInterfaces (
                  &Private->Handle,
                  &gEfiSerialIoProtocolGuid,
                  &Private->SerialIo,
                  &gEfiDevicePathProtocolGuid,
                  Private->DevicePath,
                  NULL
                  );
  if (EFI_ERROR (Status)) {
    goto Error;
  }

  //
  // Open For Child Device
  //
  Status = gBS->OpenProtocol (
                  Handle,
                  &gEfiWinNtIoProtocolGuid,
                  (VOID **) &WinNtIo,
                  This->DriverBindingHandle,
                  Private->Handle,
                  EFI_OPEN_PROTOCOL_BY_CHILD_CONTROLLER
                  );
  if (EFI_ERROR (Status)) {
    goto Error;
  }

  return EFI_SUCCESS;

Error:
  //
  // Use the Stop() function to free all resources allocated in Start()
  //
  if (Private != NULL) {
    if (Private->Handle != NULL) {
      This->Stop (This, Handle, 1, &Private->Handle);
    } else {
      if (NtHandle != INVALID_HANDLE_VALUE) {
        Private->WinNtThunk->CloseHandle (NtHandle);
      }

      if (Private->DevicePath != NULL) {
        FreePool (Private->DevicePath);
      }

      FreeUnicodeStringTable (Private->ControllerNameTable);

      FreePool (Private);
    }
  }

  This->Stop (This, Handle, 0, NULL);

  return Status;
}

EFI_STATUS
EFIAPI
WinNtSerialIoDriverBindingStop (
  IN  EFI_DRIVER_BINDING_PROTOCOL   *This,
  IN  EFI_HANDLE                    Handle,
  IN  UINTN                         NumberOfChildren,
  IN  EFI_HANDLE                    *ChildHandleBuffer
  )
/*++

Routine Description:

  TODO: Add function description

Arguments:

  This              - TODO: add argument description
  Handle            - TODO: add argument description
  NumberOfChildren  - TODO: add argument description
  ChildHandleBuffer - TODO: add argument description

Returns:

  EFI_DEVICE_ERROR - TODO: Add description for return value
  EFI_SUCCESS - TODO: Add description for return value

--*/
{
  EFI_STATUS                    Status;
  UINTN                         Index;
  BOOLEAN                       AllChildrenStopped;
  EFI_SERIAL_IO_PROTOCOL        *SerialIo;
  WIN_NT_SERIAL_IO_PRIVATE_DATA *Private;
  EFI_WIN_NT_IO_PROTOCOL        *WinNtIo;

  //
  // Complete all outstanding transactions to Controller.
  // Don't allow any new transaction to Controller to be started.
  //

  if (NumberOfChildren == 0) {
    //
    // Close the bus driver
    //
    Status = gBS->CloseProtocol (
                    Handle,
                    &gEfiWinNtIoProtocolGuid,
                    This->DriverBindingHandle,
                    Handle
                    );
    Status = gBS->CloseProtocol (
                    Handle,
                    &gEfiDevicePathProtocolGuid,
                    This->DriverBindingHandle,
                    Handle
                    );
    return Status;
  }

  AllChildrenStopped = TRUE;

  for (Index = 0; Index < NumberOfChildren; Index++) {
    Status = gBS->OpenProtocol (
                    ChildHandleBuffer[Index],
                    &gEfiSerialIoProtocolGuid,
                    (VOID **) &SerialIo,
                    This->DriverBindingHandle,
                    Handle,
                    EFI_OPEN_PROTOCOL_GET_PROTOCOL
                    );
    if (!EFI_ERROR (Status)) {
      Private = WIN_NT_SERIAL_IO_PRIVATE_DATA_FROM_THIS (SerialIo);

      ASSERT (Private->Handle == ChildHandleBuffer[Index]);

      Status = gBS->CloseProtocol (
                      Handle,
                      &gEfiWinNtIoProtocolGuid,
                      This->DriverBindingHandle,
                      ChildHandleBuffer[Index]
                      );

      Status = gBS->UninstallMultipleProtocolInterfaces (
                      ChildHandleBuffer[Index],
                      &gEfiSerialIoProtocolGuid,
                      &Private->SerialIo,
                      &gEfiDevicePathProtocolGuid,
                      Private->DevicePath,
                      NULL
                      );

      if (EFI_ERROR (Status)) {
        gBS->OpenProtocol (
              Handle,
              &gEfiWinNtIoProtocolGuid,
              (VOID **) &WinNtIo,
              This->DriverBindingHandle,
              ChildHandleBuffer[Index],
              EFI_OPEN_PROTOCOL_BY_CHILD_CONTROLLER
              );
      } else {
        Private->WinNtThunk->CloseHandle (Private->NtHandle);

        FreePool (Private->DevicePath);

        FreeUnicodeStringTable (Private->ControllerNameTable);

        FreePool (Private);
      }
    }

    if (EFI_ERROR (Status)) {
      AllChildrenStopped = FALSE;
    }
  }

  if (!AllChildrenStopped) {
    return EFI_DEVICE_ERROR;
  }

  return EFI_SUCCESS;
}

//
// Serial IO Protocol member functions
//

EFI_STATUS
EFIAPI
WinNtSerialIoReset (
  IN EFI_SERIAL_IO_PROTOCOL *This
  )
/*++

Routine Description:

  TODO: Add function description

Arguments:

  This  - TODO: add argument description

Returns:

  TODO: add return values

--*/
{
  WIN_NT_SERIAL_IO_PRIVATE_DATA *Private;
  EFI_TPL                       Tpl;

  Tpl     = gBS->RaiseTPL (TPL_NOTIFY);

  Private = WIN_NT_SERIAL_IO_PRIVATE_DATA_FROM_THIS (This);

  Private->WinNtThunk->PurgeComm (
                        Private->NtHandle,
                        PURGE_TXCLEAR | PURGE_RXCLEAR
                        );

  gBS->RestoreTPL (Tpl);

  return This->SetAttributes (
                This,
                This->Mode->BaudRate,
                This->Mode->ReceiveFifoDepth,
                This->Mode->Timeout,
                (EFI_PARITY_TYPE)This->Mode->Parity,
                (UINT8) This->Mode->DataBits,
                (EFI_STOP_BITS_TYPE)This->Mode->StopBits
                );
}

EFI_STATUS
EFIAPI
WinNtSerialIoSetAttributes (
  IN EFI_SERIAL_IO_PROTOCOL *This,
  IN UINT64                 BaudRate,
  IN UINT32                 ReceiveFifoDepth,
  IN UINT32                 Timeout,
  IN EFI_PARITY_TYPE        Parity,
  IN UINT8                  DataBits,
  IN EFI_STOP_BITS_TYPE     StopBits
  )
/*++

Routine Description:

  This function is used to set the attributes.

Arguments:

  This              - A pointer to the EFI_SERIAL_IO_PROTOCOL structrue.
  BaudRate          - The Baud rate of the serial device.
  ReceiveFifoDepth  - The request depth of fifo on receive side.
  Timeout           - the request timeout for a single charact.
  Parity            - The type of parity used in serial device.
  DataBits          - Number of deata bits used in serial device.
  StopBits          - Number of stop bits used in serial device.

Returns:
  Status code

  None

--*/
// TODO:    EFI_SUCCESS - add return value to function comment
// TODO:    EFI_DEVICE_ERROR - add return value to function comment
// TODO:    EFI_DEVICE_ERROR - add return value to function comment
// TODO:    EFI_DEVICE_ERROR - add return value to function comment
// TODO:    EFI_SUCCESS - add return value to function comment
// TODO:    EFI_DEVICE_ERROR - add return value to function comment
// TODO:    EFI_SUCCESS - add return value to function comment
{
  EFI_STATUS                    Status;
  UINTN                         Index;  
  WIN_NT_SERIAL_IO_PRIVATE_DATA *Private;
  COMMTIMEOUTS                  PortTimeOuts;
  DWORD                         ConvertedTime;
  BOOL                          Result;
  UART_DEVICE_PATH              *Uart;
  EFI_TPL                       Tpl;

  Private = WIN_NT_SERIAL_IO_PRIVATE_DATA_FROM_THIS (This);

  //
  //  Some of our arguments have defaults if a null value is passed in, and
  //   we must set the default values if a null argument is passed in.
  //
  if (BaudRate == 0) {
    BaudRate = PcdGet64 (PcdUartDefaultBaudRate);
  }

  if (ReceiveFifoDepth == 0) {
    ReceiveFifoDepth = SERIAL_FIFO_DEFAULT;
  }

  if (Timeout == 0) {
    Timeout = SERIAL_TIMEOUT_DEFAULT;
  }

  if (Parity == DefaultParity) {
    Parity = (EFI_PARITY_TYPE) (PcdGet8 (PcdUartDefaultParity));
  }

  if (DataBits == 0) {
    DataBits = PcdGet8 (PcdUartDefaultDataBits);
  }

  if (StopBits == DefaultStopBits) {
    StopBits = (EFI_STOP_BITS_TYPE) PcdGet8 (PcdUartDefaultStopBits);
  }

  //
  // Make sure all parameters are valid
  //
  if ((BaudRate > SERIAL_PORT_MAX_BAUD_RATE) || (BaudRate < SERIAL_PORT_MIN_BAUD_RATE)) {
    return EFI_INVALID_PARAMETER;
  }

  //
  //The lower baud rate supported by the serial device will be selected without exceeding the unsupported BaudRate parameter
  // 
  
  for (Index = 1; Index < (ARRAY_SIZE (mBaudRateCurrentSupport)); Index++) {
    if (BaudRate < mBaudRateCurrentSupport[Index]) {
      BaudRate = mBaudRateCurrentSupport[Index-1];
      break;
      }
  }

  if ((ReceiveFifoDepth < 1) || (ReceiveFifoDepth > SERIAL_PORT_MAX_RECEIVE_FIFO_DEPTH)) {
    return EFI_INVALID_PARAMETER;
  }

  if ((Timeout < SERIAL_PORT_MIN_TIMEOUT) || (Timeout > SERIAL_PORT_MAX_TIMEOUT)) {
    return EFI_INVALID_PARAMETER;
  }

  if ((Parity < NoParity) || (Parity > SpaceParity)) {
    return EFI_INVALID_PARAMETER;
  }

  if ((StopBits < OneStopBit) || (StopBits > TwoStopBits)) {
    return EFI_INVALID_PARAMETER;
  }

  //
  // Now we only support DataBits=7,8.
  //
  if ((DataBits < 7) || (DataBits > 8)) {
    return EFI_INVALID_PARAMETER;
  }
  
  //
  // Now we only support DataBits=7,8.
  // for DataBits = 6,7,8, StopBits can not set OneFiveStopBits.
  //
  if (StopBits == OneFiveStopBits) {
    return EFI_INVALID_PARAMETER;
  }  
  
  //
  // See if the new attributes already match the current attributes
  //
  if (Private->UartDevicePath.BaudRate       == BaudRate         &&
      Private->UartDevicePath.DataBits       == DataBits         &&
      Private->UartDevicePath.Parity         == Parity           &&
      Private->UartDevicePath.StopBits       == StopBits         &&
      Private->SerialIoMode.ReceiveFifoDepth == ReceiveFifoDepth &&
      Private->SerialIoMode.Timeout          == Timeout             ) {
    return EFI_SUCCESS;
  }

  Tpl     = gBS->RaiseTPL (TPL_NOTIFY);

  //
  //  Get current values from NT
  //
  ZeroMem (&Private->NtDCB, sizeof (DCB));
  Private->NtDCB.DCBlength = sizeof (DCB);

  if (!Private->WinNtThunk->GetCommState (Private->NtHandle, &Private->NtDCB)) {
    Private->NtError = Private->WinNtThunk->GetLastError ();
    DEBUG ((EFI_D_ERROR, "SerialSetAttributes: GetCommState %d\n", Private->NtError));
    gBS->RestoreTPL (Tpl);
    return EFI_DEVICE_ERROR;
  }

  //
  // Map EFI com setting to NT
  //
  Private->NtDCB.BaudRate         = ConvertBaud2Nt (BaudRate);
  Private->NtDCB.ByteSize         = ConvertData2Nt (DataBits);
  Private->NtDCB.Parity           = ConvertParity2Nt (Parity);
  Private->NtDCB.StopBits         = ConvertStop2Nt (StopBits);

  Private->NtDCB.fBinary          = TRUE;
  Private->NtDCB.fParity          = Private->NtDCB.Parity == NOPARITY ? FALSE : TRUE;
  Private->NtDCB.fOutxCtsFlow     = FALSE;
  Private->NtDCB.fOutxDsrFlow     = FALSE;
  Private->NtDCB.fDtrControl      = DTR_CONTROL_ENABLE;
  Private->NtDCB.fDsrSensitivity  = FALSE;
  Private->NtDCB.fOutX            = FALSE;
  Private->NtDCB.fInX             = FALSE;
  Private->NtDCB.fRtsControl      = RTS_CONTROL_ENABLE;
  Private->NtDCB.fNull            = FALSE;

  //
  //  Set new values
  //
  Result = Private->WinNtThunk->SetCommState (Private->NtHandle, &Private->NtDCB);
  if (!Result) {
    Private->NtError = Private->WinNtThunk->GetLastError ();
    DEBUG ((EFI_D_ERROR, "SerialSetAttributes: SetCommState %d\n", Private->NtError));
    gBS->RestoreTPL (Tpl);
    return EFI_DEVICE_ERROR;
  }

  //
  //  Set com port read/write timeout values
  //
  ConvertedTime = ConvertTime2Nt (Timeout);
  PortTimeOuts.ReadIntervalTimeout = MAXDWORD;
  PortTimeOuts.ReadTotalTimeoutMultiplier = 0;
  PortTimeOuts.ReadTotalTimeoutConstant = ConvertedTime;
  PortTimeOuts.WriteTotalTimeoutMultiplier = ConvertedTime == 0 ? 1 : ConvertedTime;
  PortTimeOuts.WriteTotalTimeoutConstant = 0;

  if (!Private->WinNtThunk->SetCommTimeouts (Private->NtHandle, &PortTimeOuts)) {
    Private->NtError = Private->WinNtThunk->GetLastError ();
    DEBUG ((EFI_D_ERROR, "SerialSetAttributes: SetCommTimeouts %d\n", Private->NtError));
    gBS->RestoreTPL (Tpl);
    return EFI_DEVICE_ERROR;
  }

  //
  //  Update mode
  //
  Private->SerialIoMode.BaudRate          = BaudRate;
  Private->SerialIoMode.ReceiveFifoDepth  = ReceiveFifoDepth;
  Private->SerialIoMode.Timeout           = Timeout;
  Private->SerialIoMode.Parity            = Parity;
  Private->SerialIoMode.DataBits          = DataBits;
  Private->SerialIoMode.StopBits          = StopBits;

  //
  // See if Device Path Node has actually changed
  //
  if (Private->UartDevicePath.BaudRate     == BaudRate &&
      Private->UartDevicePath.DataBits     == DataBits &&
      Private->UartDevicePath.Parity       == Parity   &&
      Private->UartDevicePath.StopBits     == StopBits    ) {
    gBS->RestoreTPL(Tpl);
    return EFI_SUCCESS;
  }

  //
  // Update the device path
  //
  Private->UartDevicePath.BaudRate  = BaudRate;
  Private->UartDevicePath.DataBits  = DataBits;
  Private->UartDevicePath.Parity    = (UINT8) Parity;
  Private->UartDevicePath.StopBits  = (UINT8) StopBits;

  Status = EFI_SUCCESS;
  if (Private->Handle != NULL) {
    Uart = (UART_DEVICE_PATH *) (
             (UINTN) Private->DevicePath
             + GetDevicePathSize (Private->ParentDevicePath)
             - END_DEVICE_PATH_LENGTH
             );
    CopyMem (Uart, &Private->UartDevicePath, sizeof (UART_DEVICE_PATH));
    Status = gBS->ReinstallProtocolInterface (
                    Private->Handle,
                    &gEfiDevicePathProtocolGuid,
                    Private->DevicePath,
                    Private->DevicePath
                    );
  }

  gBS->RestoreTPL (Tpl);

  return Status;
}

EFI_STATUS
EFIAPI
WinNtSerialIoSetControl (
  IN EFI_SERIAL_IO_PROTOCOL *This,
  IN UINT32                 Control
  )
/*++

Routine Description:

  TODO: Add function description

Arguments:

  This    - TODO: add argument description
  Control - TODO: add argument description

Returns:

  EFI_DEVICE_ERROR - TODO: Add description for return value
  EFI_DEVICE_ERROR - TODO: Add description for return value
  EFI_SUCCESS - TODO: Add description for return value

--*/
{
  WIN_NT_SERIAL_IO_PRIVATE_DATA *Private;
  BOOL                          Result;
  DCB                           Dcb;
  EFI_TPL                       Tpl;
  UART_FLOW_CONTROL_DEVICE_PATH *FlowControl;
  EFI_STATUS                    Status;

  //
  // first determine the parameter is invalid
  //
  if (Control & (~(EFI_SERIAL_REQUEST_TO_SEND | EFI_SERIAL_DATA_TERMINAL_READY |
                   EFI_SERIAL_HARDWARE_LOOPBACK_ENABLE | EFI_SERIAL_SOFTWARE_LOOPBACK_ENABLE | 
                   EFI_SERIAL_HARDWARE_FLOW_CONTROL_ENABLE))) {
    return EFI_UNSUPPORTED;
  }

  Tpl     = gBS->RaiseTPL (TPL_NOTIFY);

  Private = WIN_NT_SERIAL_IO_PRIVATE_DATA_FROM_THIS (This);

  Result  = Private->WinNtThunk->GetCommState (Private->NtHandle, &Dcb);

  if (!Result) {
    Private->NtError = Private->WinNtThunk->GetLastError ();
    DEBUG ((EFI_D_ERROR, "SerialSetControl: GetCommState %d\n", Private->NtError));
    gBS->RestoreTPL (Tpl);
    return EFI_DEVICE_ERROR;
  }

  Dcb.fRtsControl                 = RTS_CONTROL_DISABLE;
  Dcb.fDtrControl                 = DTR_CONTROL_DISABLE;
  Private->HardwareFlowControl    = FALSE;
  Private->SoftwareLoopbackEnable = FALSE;
  Private->HardwareLoopbackEnable = FALSE;

  if (Control & EFI_SERIAL_REQUEST_TO_SEND) {
    Dcb.fRtsControl = RTS_CONTROL_ENABLE;
  }

  if (Control & EFI_SERIAL_DATA_TERMINAL_READY) {
    Dcb.fDtrControl = DTR_CONTROL_ENABLE;
  }

  if (Control & EFI_SERIAL_HARDWARE_FLOW_CONTROL_ENABLE) {
    Private->HardwareFlowControl = TRUE;
  }

  if (Control & EFI_SERIAL_SOFTWARE_LOOPBACK_ENABLE) {
    Private->SoftwareLoopbackEnable = TRUE;
  }

  if (Control & EFI_SERIAL_HARDWARE_LOOPBACK_ENABLE) {
    Private->HardwareLoopbackEnable = TRUE;
  }

  Result = Private->WinNtThunk->SetCommState (
                                  Private->NtHandle,
                                  &Dcb
                                  );

  if (!Result) {
    Private->NtError = Private->WinNtThunk->GetLastError ();
    DEBUG ((EFI_D_ERROR, "SerialSetControl: SetCommState %d\n", Private->NtError));
    gBS->RestoreTPL (Tpl);
    return EFI_DEVICE_ERROR;
  }

  Status = EFI_SUCCESS;
  if (Private->Handle != NULL) {
    FlowControl = (UART_FLOW_CONTROL_DEVICE_PATH *) (
                    (UINTN) Private->DevicePath
                    + GetDevicePathSize (Private->ParentDevicePath)
                    - END_DEVICE_PATH_LENGTH
                    + sizeof (UART_DEVICE_PATH)
                    );
    if (IsUartFlowControlNode (FlowControl) &&
        ((FlowControl->FlowControlMap == UART_FLOW_CONTROL_HARDWARE) ^ Private->HardwareFlowControl)) {
      //
      // Flow Control setting is changed, need to reinstall device path protocol
      //
      FlowControl->FlowControlMap = Private->HardwareFlowControl ? UART_FLOW_CONTROL_HARDWARE : 0;
      Status = gBS->ReinstallProtocolInterface (
                      Private->Handle,
                      &gEfiDevicePathProtocolGuid,
                      Private->DevicePath,
                      Private->DevicePath
                      );
    }
  }

  gBS->RestoreTPL (Tpl);

  return Status;
}

EFI_STATUS
EFIAPI
WinNtSerialIoGetControl (
  IN  EFI_SERIAL_IO_PROTOCOL  *This,
  OUT UINT32                  *Control
  )
/*++

Routine Description:

  TODO: Add function description

Arguments:

  This    - TODO: add argument description
  Control - TODO: add argument description

Returns:

  EFI_DEVICE_ERROR - TODO: Add description for return value
  EFI_DEVICE_ERROR - TODO: Add description for return value
  EFI_DEVICE_ERROR - TODO: Add description for return value
  EFI_SUCCESS - TODO: Add description for return value

--*/
{
  WIN_NT_SERIAL_IO_PRIVATE_DATA *Private;
  DWORD                         ModemStatus;
  DWORD                         Errors;
  UINT32                        Bits;
  DCB                           Dcb;
  EFI_TPL                       Tpl;

  Tpl     = gBS->RaiseTPL (TPL_NOTIFY);

  Private = WIN_NT_SERIAL_IO_PRIVATE_DATA_FROM_THIS (This);

  //
  //  Get modem status
  //
  if (!Private->WinNtThunk->GetCommModemStatus (Private->NtHandle, &ModemStatus)) {
    Private->NtError = Private->WinNtThunk->GetLastError ();
    gBS->RestoreTPL (Tpl);
    return EFI_DEVICE_ERROR;
  }

  Bits = 0;
  if (ModemStatus & MS_CTS_ON) {
    Bits |= EFI_SERIAL_CLEAR_TO_SEND;
  }

  if (ModemStatus & MS_DSR_ON) {
    Bits |= EFI_SERIAL_DATA_SET_READY;
  }

  if (ModemStatus & MS_RING_ON) {
    Bits |= EFI_SERIAL_RING_INDICATE;
  }

  if (ModemStatus & MS_RLSD_ON) {
    Bits |= EFI_SERIAL_CARRIER_DETECT;
  }

  //
  // Get ctrl status
  //
  if (!Private->WinNtThunk->GetCommState (Private->NtHandle, &Dcb)) {
    Private->NtError = Private->WinNtThunk->GetLastError ();
    DEBUG ((EFI_D_ERROR, "SerialGetControl: GetCommState %d\n", Private->NtError));
    gBS->RestoreTPL (Tpl);
    return EFI_DEVICE_ERROR;
  }

  if (Dcb.fDtrControl == DTR_CONTROL_ENABLE) {
    Bits |= EFI_SERIAL_DATA_TERMINAL_READY;
  }

  if (Dcb.fRtsControl == RTS_CONTROL_ENABLE) {
    Bits |= EFI_SERIAL_REQUEST_TO_SEND;
  }

  if (Private->HardwareFlowControl) {
    Bits |= EFI_SERIAL_HARDWARE_FLOW_CONTROL_ENABLE;
  }

  if (Private->SoftwareLoopbackEnable) {
    Bits |= EFI_SERIAL_SOFTWARE_LOOPBACK_ENABLE;
  }

  if (Private->HardwareLoopbackEnable) {
    Bits |= EFI_SERIAL_HARDWARE_LOOPBACK_ENABLE;
  }

  //
  //  Get input buffer status
  //
  if (!Private->WinNtThunk->ClearCommError (Private->NtHandle, &Errors, &Private->NtComStatus)) {
    Private->NtError = Private->WinNtThunk->GetLastError ();
    DEBUG ((EFI_D_ERROR, "SerialGetControl: ClearCommError %d\n", Private->NtError));
    gBS->RestoreTPL (Tpl);
    return EFI_DEVICE_ERROR;
  }

  if (Private->NtComStatus.cbInQue == 0) {
    Bits |= EFI_SERIAL_INPUT_BUFFER_EMPTY;
  }

  *Control = Bits;

  gBS->RestoreTPL (Tpl);

  return EFI_SUCCESS;
}

EFI_STATUS
EFIAPI
WinNtSerialIoWrite (
  IN EFI_SERIAL_IO_PROTOCOL   *This,
  IN OUT UINTN                *BufferSize,
  IN VOID                     *Buffer
  )
/*++

Routine Description:

  TODO: Add function description

Arguments:

  This        - TODO: add argument description
  BufferSize  - TODO: add argument description
  Buffer      - TODO: add argument description

Returns:

  EFI_DEVICE_ERROR - TODO: Add description for return value
  EFI_SUCCESS - TODO: Add description for return value

--*/
{
  WIN_NT_SERIAL_IO_PRIVATE_DATA *Private;
  UINT8                         *ByteBuffer;
  UINTN                         TotalBytesWritten;
  DWORD                         BytesToGo;
  DWORD                         BytesWritten;
  BOOL                          Result;
  UINT32                        Index;
  UINT32                        Control;
  EFI_TPL                       Tpl;

  Tpl               = gBS->RaiseTPL (TPL_NOTIFY);

  Private           = WIN_NT_SERIAL_IO_PRIVATE_DATA_FROM_THIS (This);

  ByteBuffer        = (UINT8 *) Buffer;
  TotalBytesWritten = 0;

  if (Private->SoftwareLoopbackEnable || Private->HardwareLoopbackEnable) {
    for (Index = 0; Index < *BufferSize; Index++) {
      if (IsaSerialFifoAdd (&Private->Fifo, ByteBuffer[Index]) == EFI_SUCCESS) {
        TotalBytesWritten++;
      } else {
        break;
      }
    }
  } else {
    BytesToGo = (DWORD) (*BufferSize);

    do {
      if (Private->HardwareFlowControl) {
        //
        // Send RTS
        //
        WinNtSerialIoGetControl (&Private->SerialIo, &Control);
        Control |= EFI_SERIAL_REQUEST_TO_SEND;
        WinNtSerialIoSetControl (&Private->SerialIo, Control);
      }

      //
      //  Do the write
      //
      Result = Private->WinNtThunk->WriteFile (
                                      Private->NtHandle,
                                      &ByteBuffer[TotalBytesWritten],
                                      BytesToGo,
                                      &BytesWritten,
                                      NULL
                                      );

      if (Private->HardwareFlowControl) {
        //
        // Assert RTS
        //
        WinNtSerialIoGetControl (&Private->SerialIo, &Control);
        Control &= ~ (UINT32) EFI_SERIAL_REQUEST_TO_SEND;
        WinNtSerialIoSetControl (&Private->SerialIo, Control);
      }

      TotalBytesWritten += BytesWritten;
      BytesToGo -= BytesWritten;
      if (!Result) {
        Private->NtError = Private->WinNtThunk->GetLastError ();
        DEBUG ((EFI_D_ERROR, "SerialWrite: FileWrite %d\n", Private->NtError));
        *BufferSize = TotalBytesWritten;
        gBS->RestoreTPL (Tpl);
        return EFI_DEVICE_ERROR;
      }
    } while (BytesToGo > 0);
  }

  *BufferSize = TotalBytesWritten;

  gBS->RestoreTPL (Tpl);

  return EFI_SUCCESS;
}

EFI_STATUS
EFIAPI
WinNtSerialIoRead (
  IN  EFI_SERIAL_IO_PROTOCOL  *This,
  IN  OUT UINTN               *BufferSize,
  OUT VOID                    *Buffer
  )
/*++

Routine Description:

  TODO: Add function description

Arguments:

  This        - TODO: add argument description
  BufferSize  - TODO: add argument description
  Buffer      - TODO: add argument description

Returns:

  EFI_DEVICE_ERROR - TODO: Add description for return value

--*/
{
  WIN_NT_SERIAL_IO_PRIVATE_DATA *Private;
  BOOL                          Result;
  DWORD                         BytesRead;
  EFI_STATUS                    Status;
  UINT32                        Index;
  UINT8                         Data;
  UINT32                        Control;
  EFI_TPL                       Tpl;

  Tpl     = gBS->RaiseTPL (TPL_NOTIFY);

  Private = WIN_NT_SERIAL_IO_PRIVATE_DATA_FROM_THIS (This);

  //
  //  Do the read
  //
  if (Private->SoftwareLoopbackEnable || Private->HardwareLoopbackEnable) {
    for (Index = 0, BytesRead = 0; Index < *BufferSize; Index++) {
      if (IsaSerialFifoRemove (&Private->Fifo, &Data) == EFI_SUCCESS) {
        ((UINT8 *) Buffer)[Index] = Data;
        BytesRead++;
      } else {
        break;
      }
    }
  } else {
    if (Private->HardwareFlowControl) {
      WinNtSerialIoGetControl (&Private->SerialIo, &Control);
      Control |= EFI_SERIAL_DATA_TERMINAL_READY;
      WinNtSerialIoSetControl (&Private->SerialIo, Control);
    }

    Result = Private->WinNtThunk->ReadFile (
                                    Private->NtHandle,
                                    Buffer,
                                    (DWORD) *BufferSize,
                                    &BytesRead,
                                    NULL
                                    );

    if (Private->HardwareFlowControl) {
      WinNtSerialIoGetControl (&Private->SerialIo, &Control);
      Control &= ~ (UINT32) EFI_SERIAL_DATA_TERMINAL_READY;
      WinNtSerialIoSetControl (&Private->SerialIo, Control);
    }

    if (!Result) {
      Private->NtError = Private->WinNtThunk->GetLastError ();
      gBS->RestoreTPL (Tpl);
      return EFI_DEVICE_ERROR;
    }
  }

  if (BytesRead != *BufferSize) {
    Status = EFI_TIMEOUT;
  } else {
    Status = EFI_SUCCESS;
  }

  *BufferSize = (UINTN) BytesRead;

  gBS->RestoreTPL (Tpl);

  return Status;
}

BOOLEAN
IsaSerialFifoFull (
  IN SERIAL_DEV_FIFO *Fifo
  )
/*++

  Routine Description:
  Detect whether specific FIFO is full or not

  Arguments:
  Fifo  SERIAL_DEV_FIFO *: A pointer to the Data Structure SERIAL_DEV_FIFO

  Returns:
  TRUE:  the FIFO is full
  FALSE: the FIFO is not full

--*/
{
  if (Fifo->Surplus == 0) {
    return TRUE;
  }

  return FALSE;
}

BOOLEAN
IsaSerialFifoEmpty (
  IN SERIAL_DEV_FIFO *Fifo
  )
/*++

  Routine Description:
  Detect whether specific FIFO is empty or not

  Arguments:
    Fifo  SERIAL_DEV_FIFO *: A pointer to the Data Structure SERIAL_DEV_FIFO

  Returns:
    TRUE:  the FIFO is empty
    FALSE: the FIFO is not empty

--*/
{
  if (Fifo->Surplus == SERIAL_MAX_BUFFER_SIZE) {
    return TRUE;
  }

  return FALSE;
}

EFI_STATUS
IsaSerialFifoAdd (
  IN SERIAL_DEV_FIFO *Fifo,
  IN UINT8           Data
  )
/*++

  Routine Description:
  Add data to specific FIFO

  Arguments:
    Fifo  SERIAL_DEV_FIFO *: A pointer to the Data Structure SERIAL_DEV_FIFO
    Data  UINT8: the data added to FIFO

  Returns:
    EFI_SUCCESS:  Add data to specific FIFO successfully
    EFI_OUT_RESOURCE: Failed to add data because FIFO is already full

--*/
// TODO:    EFI_OUT_OF_RESOURCES - add return value to function comment
{
  //
  // if FIFO full can not add data
  //
  if (IsaSerialFifoFull (Fifo)) {
    return EFI_OUT_OF_RESOURCES;
  }

  //
  // FIFO is not full can add data
  //
  Fifo->Data[Fifo->Last] = Data;
  Fifo->Surplus--;
  Fifo->Last++;
  if (Fifo->Last >= SERIAL_MAX_BUFFER_SIZE) {
    Fifo->Last = 0;
  }

  return EFI_SUCCESS;
}

EFI_STATUS
IsaSerialFifoRemove (
  IN  SERIAL_DEV_FIFO *Fifo,
  OUT UINT8           *Data
  )
/*++

  Routine Description:
  Remove data from specific FIFO

  Arguments:
    Fifo  SERIAL_DEV_FIFO *: A pointer to the Data Structure SERIAL_DEV_FIFO
    Data  UINT8*: the data removed from FIFO

  Returns:
    EFI_SUCCESS:  Remove data from specific FIFO successfully
    EFI_OUT_RESOURCE: Failed to remove data because FIFO is empty

--*/
// TODO:    EFI_OUT_OF_RESOURCES - add return value to function comment
{
  //
  // if FIFO is empty, no data can remove
  //
  if (IsaSerialFifoEmpty (Fifo)) {
    return EFI_OUT_OF_RESOURCES;
  }

  //
  // FIFO is not empty, can remove data
  //
  *Data = Fifo->Data[Fifo->First];
  Fifo->Surplus++;
  Fifo->First++;
  if (Fifo->First >= SERIAL_MAX_BUFFER_SIZE) {
    Fifo->First = 0;
  }

  return EFI_SUCCESS;
}