EmbeddedPkg/GdbStub/SerialIo.c - edk2 - Git at Google

 /** @file
   Serial IO Abstraction for GDB stub. This allows an EFI consoles that shows up on the system
   running GDB. One consle for error information and another console for user input/output.

   Basic packet format is $packet-data#checksum. So every comand has 4 bytes of overhead: $,
   #, 0, 0. The 0 and 0 are the ascii characters for the checksum.


   Copyright (c) 2008 - 2009, Apple Inc. 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 <GdbStubInternal.h>

 //
 // Set TRUE if F Reply package signals a ctrl-c. We can not process the Ctrl-c
 // here we need to wait for the periodic callback to do this.
 //
 BOOLEAN gCtrlCBreakFlag = FALSE;

 //
 // If the periodic callback is called while we are processing an F packet we need
 // to let the callback know to not read from the serail stream as it could steal
 // characters from the F reponse packet
 //
 BOOLEAN gProcessingFPacket = FALSE;

 /**
   Process a control-C break message.

   Currently a place holder, remove the ASSERT when it gets implemented.

   @param  ErrNo   Error infomration from the F reply packet or other source

 **/

 VOID
 GdbCtrlCBreakMessage (
   IN  UINTN ErrNo
   )
 {
   // See D.10.5 of gdb.pdf
   // This should look like a break message. Should look like SIGINT

   /* TODO: Make sure if we should do anything with ErrNo */
   //Turn on the global Ctrl-C flag.
   gCtrlCBreakFlag = TRUE;
 }


 /**
   Parse the F reply packet and extract the return value and an ErrNo if it exists.

   @param  Packet  Packet to parse like an F reply packet
   @param  ErrNo   Buffer to hold Count bytes that were read

   @retval -1      Error, not a valid F reply packet
   @retval other   Return the return code from the F reply packet

 **/
 INTN
 GdbParseFReplyPacket (
   IN  CHAR8   *Packet,
   OUT UINTN   *ErrNo
   )
 {
   INTN   RetCode;

   if (Packet[0] != 'F') {
     // A valid responce would be an F packet
     return -1;
   }

   RetCode = AsciiStrHexToUintn (&Packet[1]);

   // Find 1st comma
   for (;*Packet != '\0' && *Packet != ',';  Packet++);
   if (*Packet == '\0') {
     *ErrNo = 0;
     return RetCode;
   }

   *ErrNo = AsciiStrHexToUintn (++Packet);

   // Find 2nd comma
   for (;*Packet != '\0' && *Packet != ',';  Packet++);
   if (*Packet == '\0') {
     return RetCode;
   }

   if (*(++Packet) == 'C') {
     GdbCtrlCBreakMessage (*ErrNo);
   }

   return RetCode;
 }


 /**
   Read data from a FileDescriptor. On success number of bytes read is returned. Zero indicates
   the end of a file. On error -1 is returned. If count is zero, GdbRead returns zero.

   @param  FileDescriptor   Device to talk to.
   @param  Buffer           Buffer to hold Count bytes that were read
   @param  Count            Number of bytes to transfer.

   @retval -1               Error
   @retval {other}          Number of bytes read.

 **/
 INTN
 GdbRead (
   IN  INTN    FileDescriptor,
   OUT VOID    *Buffer,
   IN  UINTN   Count
   )
 {
   CHAR8   Packet[128];
   UINTN   Size;
   INTN    RetCode;
   UINTN   ErrNo;
   BOOLEAN ReceiveDone = FALSE;

   // Send:
   // "Fread,XX,YYYYYYYY,XX
   //
   // XX - FileDescriptor in ASCII
   // YYYYYYYY - Buffer address in ASCII
   // XX - Count in ASCII
   // SS - check sum
   //
   Size = AsciiSPrint (Packet, sizeof (Packet), "Fread,%x,%x,%x", FileDescriptor, Buffer, Count);
   // Packet array is too small if you got this ASSERT
   ASSERT (Size < sizeof (Packet));

   gProcessingFPacket = TRUE;
   SendPacket (Packet);
   Print ((CHAR16 *)L"Packet sent..\n");

   do {
     // Reply:
     ReceivePacket (Packet, sizeof (Packet));
     Print ((CHAR16 *)L"Command received..%c\n", Packet[0]);

     // Process GDB commands
     switch (Packet[0]) {
       //Write memory command.
       //M addr,length:XX...
       case    'M':
         WriteToMemory (Packet);
         break;

       //Fretcode, errno, Ctrl-C flag
       //retcode - Count read
       case    'F':
         //Once target receives F reply packet that means the previous
         //transactions are finished.
         ReceiveDone = TRUE;
         break;

       //Send empty buffer
       default    :
         SendNotSupported();
         break;
     }
   } while (ReceiveDone == FALSE);

   RetCode = GdbParseFReplyPacket (Packet, &ErrNo);
   Print ((CHAR16 *)L"RetCode: %x..ErrNo: %x..\n", RetCode, ErrNo);

   if (ErrNo > 0) {
     //Send error to the host if there is any.
     SendError ((UINT8)ErrNo);
   }

   gProcessingFPacket = FALSE;

   return RetCode;
 }


 /**
   Write data to a FileDescriptor. On success number of bytes written is returned. Zero indicates
   nothing was written. On error -1 is returned.

   @param  FileDescriptor   Device to talk to.
   @param  Buffer           Buffer to hold Count bytes that are to be written
   @param  Count            Number of bytes to transfer.

   @retval -1               Error
   @retval {other}          Number of bytes written.

 **/
 INTN
 GdbWrite (
   IN  INTN          FileDescriptor,
   OUT CONST VOID    *Buffer,
   IN  UINTN         Count
   )
 {
   CHAR8   Packet[128];
   UINTN   Size;
   INTN    RetCode;
   UINTN   ErrNo;
   BOOLEAN ReceiveDone = FALSE;

   // Send:
   // #Fwrite,XX,YYYYYYYY,XX$SS
   //
   // XX - FileDescriptor in ASCII
   // YYYYYYYY - Buffer address in ASCII
   // XX - Count in ASCII
   // SS - check sum
   //
   Size = AsciiSPrint (Packet, sizeof (Packet), "Fwrite,%x,%x,%x", FileDescriptor, Buffer, Count);
   // Packet array is too small if you got this ASSERT
   ASSERT (Size < sizeof (Packet));

   SendPacket (Packet);
   Print ((CHAR16 *)L"Packet sent..\n");

   do {
     // Reply:
     ReceivePacket (Packet, sizeof (Packet));
     Print ((CHAR16 *)L"Command received..%c\n", Packet[0]);

     // Process GDB commands
     switch (Packet[0]) {
       //Read memory command.
       //m addr,length.
       case    'm':
         ReadFromMemory (Packet);
         break;

       //Fretcode, errno, Ctrl-C flag
       //retcode - Count read
       case    'F':
         //Once target receives F reply packet that means the previous
         //transactions are finished.
         ReceiveDone = TRUE;
         break;

       //Send empty buffer
       default    :
         SendNotSupported();
         break;
     }
   } while (ReceiveDone == FALSE);

   RetCode = GdbParseFReplyPacket (Packet, &ErrNo);
   Print ((CHAR16 *)L"RetCode: %x..ErrNo: %x..\n", RetCode, ErrNo);

   //Send error to the host if there is any.
   if (ErrNo > 0) {
     SendError((UINT8)ErrNo);
   }

   return RetCode;
 }


 /**
   Reset the serial device.

   @param  This              Protocol instance pointer.

   @retval EFI_SUCCESS       The device was reset.
   @retval EFI_DEVICE_ERROR  The serial device could not be reset.

 **/
 EFI_STATUS
 EFIAPI
 GdbSerialReset (
   IN EFI_SERIAL_IO_PROTOCOL  *This
   )
 {
   return EFI_SUCCESS;
 }


 /**
   Sets the baud rate, receive FIFO depth, transmit/receice time out, parity,
   data buts, and stop bits on a serial device.

   @param  This             Protocol instance pointer.
   @param  BaudRate         The requested baud rate. A BaudRate value of 0 will use the the
                            device's default interface speed.
   @param  ReveiveFifoDepth The requested depth of the FIFO on the receive side of the
                            serial interface. A ReceiveFifoDepth value of 0 will use
                            the device's dfault FIFO depth.
   @param  Timeout          The requested time out for a single character in microseconds.
                            This timeout applies to both the transmit and receive side of the
                            interface. A Timeout value of 0 will use the device's default time
                            out value.
   @param  Parity           The type of parity to use on this serial device. A Parity value of
                            DefaultParity will use the device's default parity value.
   @param  DataBits         The number of data bits to use on the serial device. A DataBits
                            vaule of 0 will use the device's default data bit setting.
   @param  StopBits         The number of stop bits to use on this serial device. A StopBits
                            value of DefaultStopBits will use the device's default number of
                            stop bits.

   @retval EFI_SUCCESS      The device was reset.
   @retval EFI_DEVICE_ERROR The serial device could not be reset.

 **/
 EFI_STATUS
 EFIAPI
 GdbSerialSetAttributes (
   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
   )
 {
   return EFI_UNSUPPORTED;
 }


 /**
   Set the control bits on a serial device

   @param  This             Protocol instance pointer.
   @param  Control          Set the bits of Control that are settable.

   @retval EFI_SUCCESS      The new control bits were set on the serial device.
   @retval EFI_UNSUPPORTED  The serial device does not support this operation.
   @retval EFI_DEVICE_ERROR The serial device is not functioning correctly.

 **/
 EFI_STATUS
 EFIAPI
 GdbSerialSetControl (
   IN EFI_SERIAL_IO_PROTOCOL  *This,
   IN UINT32                  Control
   )
 {
   return EFI_UNSUPPORTED;
 }


 /**
   Retrieves the status of thecontrol bits on a serial device

   @param  This              Protocol instance pointer.
   @param  Control           A pointer to return the current Control signals from the serial device.

   @retval EFI_SUCCESS       The control bits were read from the serial device.
   @retval EFI_DEVICE_ERROR  The serial device is not functioning correctly.

 **/
 EFI_STATUS
 EFIAPI
 GdbSerialGetControl (
   IN EFI_SERIAL_IO_PROTOCOL  *This,
   OUT UINT32                 *Control
   )
 {
   return EFI_UNSUPPORTED;
 }


 /**
   Writes data to a serial device.

   @param  This              Protocol instance pointer.
   @param  BufferSize        On input, the size of the Buffer. On output, the amount of
                             data actually written.
   @param  Buffer            The buffer of data to write

   @retval EFI_SUCCESS       The data was written.
   @retval EFI_DEVICE_ERROR  The device reported an error.
   @retval EFI_TIMEOUT       The data write was stopped due to a timeout.

 **/
 EFI_STATUS
 EFIAPI
 GdbSerialWrite (
   IN EFI_SERIAL_IO_PROTOCOL  *This,
   IN OUT UINTN               *BufferSize,
   IN VOID                    *Buffer
   )
 {
   GDB_SERIAL_DEV  *SerialDev;
   UINTN            Return;

   SerialDev = GDB_SERIAL_DEV_FROM_THIS (This);

   Return = GdbWrite (SerialDev->OutFileDescriptor, Buffer, *BufferSize);
   if (Return == (UINTN)-1) {
     return EFI_DEVICE_ERROR;
   }

   if (Return != *BufferSize) {
     *BufferSize = Return;
   }

   return EFI_SUCCESS;
 }

 /**
   Writes data to a serial device.

   @param  This              Protocol instance pointer.
   @param  BufferSize        On input, the size of the Buffer. On output, the amount of
                             data returned in Buffer.
   @param  Buffer            The buffer to return the data into.

   @retval EFI_SUCCESS       The data was read.
   @retval EFI_DEVICE_ERROR  The device reported an error.
   @retval EFI_TIMEOUT       The data write was stopped due to a timeout.

 **/

 EFI_STATUS
 EFIAPI
 GdbSerialRead (
   IN EFI_SERIAL_IO_PROTOCOL  *This,
   IN OUT UINTN               *BufferSize,
   OUT VOID                   *Buffer
   )
 {
   GDB_SERIAL_DEV  *SerialDev;
   UINTN            Return;

   SerialDev = GDB_SERIAL_DEV_FROM_THIS (This);

   Return = GdbRead (SerialDev->InFileDescriptor, Buffer, *BufferSize);
   if (Return == (UINTN)-1) {
     return EFI_DEVICE_ERROR;
   }

   if (Return != *BufferSize) {
     *BufferSize = Return;
   }

   return EFI_SUCCESS;
 }


 //
 // Template used to initailize the GDB Serial IO protocols
 //
 GDB_SERIAL_DEV gdbSerialDevTemplate = {
   GDB_SERIAL_DEV_SIGNATURE,
   NULL,

   { // SerialIo
     SERIAL_IO_INTERFACE_REVISION,
     GdbSerialReset,
     GdbSerialSetAttributes,
     GdbSerialSetControl,
     GdbSerialGetControl,
     GdbSerialWrite,
     GdbSerialRead,
     NULL
   },
   { // SerialMode
     0,      // ControlMask
     0,      // Timeout
     0,      // BaudRate
     1,      // RceiveFifoDepth
     0,      // DataBits
     0,      // Parity
     0       // StopBits
   },
   {
     {
       {
         HARDWARE_DEVICE_PATH,
         HW_VENDOR_DP,
         {
           (UINT8) (sizeof (VENDOR_DEVICE_PATH) + sizeof (UINT32)),
           (UINT8) ((sizeof (VENDOR_DEVICE_PATH) + sizeof (UINT32)) >> 8)
         },
       },
       EFI_SERIAL_IO_PROTOCOL_GUID
     },
     0,
     {
       END_DEVICE_PATH_TYPE,
       END_ENTIRE_DEVICE_PATH_SUBTYPE,
       {
         (UINT8) (sizeof (EFI_DEVICE_PATH_PROTOCOL)),
         (UINT8) (sizeof (EFI_DEVICE_PATH_PROTOCOL) >> 8)
       }
     },
   },
   GDB_STDIN,
   GDB_STDOUT
 };


 /**
   Make two serial consoles: 1) StdIn and StdOut via GDB. 2) StdErr via GDB.

   These console show up on the remote system running GDB

 **/
 VOID
 GdbInitializeSerialConsole (
   VOID
   )
 {
   EFI_STATUS      Status;
   GDB_SERIAL_DEV  *StdOutSerialDev;
   GDB_SERIAL_DEV  *StdErrSerialDev;

   // Use the template to make a copy of the Serial Console private data structure.
   StdOutSerialDev = AllocateCopyPool (sizeof (GDB_SERIAL_DEV),  &gdbSerialDevTemplate);
   ASSERT (StdOutSerialDev != NULL);

   // Fixup pointer after the copy
   StdOutSerialDev->SerialIo.Mode = &StdOutSerialDev->SerialMode;

   StdErrSerialDev = AllocateCopyPool (sizeof (GDB_SERIAL_DEV),  &gdbSerialDevTemplate);
   ASSERT (StdErrSerialDev != NULL);

   // Fixup pointer and modify stuff that is different for StdError
   StdErrSerialDev->SerialIo.Mode = &StdErrSerialDev->SerialMode;
   StdErrSerialDev->DevicePath.Index = 1;
   StdErrSerialDev->OutFileDescriptor = GDB_STDERR;

   // Make a new handle with Serial IO protocol and its device path on it.
   Status = gBS->InstallMultipleProtocolInterfaces (
                   &StdOutSerialDev->Handle,
                   &gEfiSerialIoProtocolGuid,   &StdOutSerialDev->SerialIo,
                   &gEfiDevicePathProtocolGuid, &StdOutSerialDev->DevicePath,
                   NULL
                   );
   ASSERT_EFI_ERROR (Status);

   // Make a new handle with Serial IO protocol and its device path on it.
   Status = gBS->InstallMultipleProtocolInterfaces (
                   &StdErrSerialDev->Handle,
                   &gEfiSerialIoProtocolGuid,   &StdErrSerialDev->SerialIo,
                   &gEfiDevicePathProtocolGuid, &StdErrSerialDev->DevicePath,
                   NULL
                   );
   ASSERT_EFI_ERROR (Status);
 }
	/** @file
	Serial IO Abstraction for GDB stub. This allows an EFI consoles that shows up on the system
	running GDB. One consle for error information and another console for user input/output.

	Basic packet format is $packet-data#checksum. So every comand has 4 bytes of overhead: $,
	#, 0, 0. The 0 and 0 are the ascii characters for the checksum.


	Copyright (c) 2008 - 2009, Apple Inc. 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 <GdbStubInternal.h>

	//
	// Set TRUE if F Reply package signals a ctrl-c. We can not process the Ctrl-c
	// here we need to wait for the periodic callback to do this.
	//
	BOOLEAN gCtrlCBreakFlag = FALSE;

	//
	// If the periodic callback is called while we are processing an F packet we need
	// to let the callback know to not read from the serail stream as it could steal
	// characters from the F reponse packet
	//
	BOOLEAN gProcessingFPacket = FALSE;

	/**
	Process a control-C break message.

	Currently a place holder, remove the ASSERT when it gets implemented.

	@param ErrNo Error infomration from the F reply packet or other source

	**/

	VOID
	GdbCtrlCBreakMessage (
	IN UINTN ErrNo
	)
	{
	// See D.10.5 of gdb.pdf
	// This should look like a break message. Should look like SIGINT

	/* TODO: Make sure if we should do anything with ErrNo */
	//Turn on the global Ctrl-C flag.
	gCtrlCBreakFlag = TRUE;
	}


	/**
	Parse the F reply packet and extract the return value and an ErrNo if it exists.

	@param Packet Packet to parse like an F reply packet
	@param ErrNo Buffer to hold Count bytes that were read

	@retval -1 Error, not a valid F reply packet
	@retval other Return the return code from the F reply packet

	**/
	INTN
	GdbParseFReplyPacket (
	IN CHAR8 *Packet,
	OUT UINTN *ErrNo
	)
	{
	INTN RetCode;

	if (Packet[0] != 'F') {
	// A valid responce would be an F packet
	return -1;
	}

	RetCode = AsciiStrHexToUintn (&Packet[1]);

	// Find 1st comma
	for (;Packet != '\0' && Packet != ','; Packet++);
	if (*Packet == '\0') {
	*ErrNo = 0;
	return RetCode;
	}

	*ErrNo = AsciiStrHexToUintn (++Packet);

	// Find 2nd comma
	for (;Packet != '\0' && Packet != ','; Packet++);
	if (*Packet == '\0') {
	return RetCode;
	}

	if (*(++Packet) == 'C') {
	GdbCtrlCBreakMessage (*ErrNo);
	}

	return RetCode;
	}


	/**
	Read data from a FileDescriptor. On success number of bytes read is returned. Zero indicates
	the end of a file. On error -1 is returned. If count is zero, GdbRead returns zero.

	@param FileDescriptor Device to talk to.
	@param Buffer Buffer to hold Count bytes that were read
	@param Count Number of bytes to transfer.

	@retval -1 Error
	@retval {other} Number of bytes read.

	**/
	INTN
	GdbRead (
	IN INTN FileDescriptor,
	OUT VOID *Buffer,
	IN UINTN Count
	)
	{
	CHAR8 Packet[128];
	UINTN Size;
	INTN RetCode;
	UINTN ErrNo;
	BOOLEAN ReceiveDone = FALSE;

	// Send:
	// "Fread,XX,YYYYYYYY,XX
	//
	// XX - FileDescriptor in ASCII
	// YYYYYYYY - Buffer address in ASCII
	// XX - Count in ASCII
	// SS - check sum
	//
	Size = AsciiSPrint (Packet, sizeof (Packet), "Fread,%x,%x,%x", FileDescriptor, Buffer, Count);
	// Packet array is too small if you got this ASSERT
	ASSERT (Size < sizeof (Packet));

	gProcessingFPacket = TRUE;
	SendPacket (Packet);
	Print ((CHAR16 *)L"Packet sent..\n");

	do {
	// Reply:
	ReceivePacket (Packet, sizeof (Packet));
	Print ((CHAR16 *)L"Command received..%c\n", Packet[0]);

	// Process GDB commands
	switch (Packet[0]) {
	//Write memory command.
	//M addr,length:XX...
	case 'M':
	WriteToMemory (Packet);
	break;

	//Fretcode, errno, Ctrl-C flag
	//retcode - Count read
	case 'F':
	//Once target receives F reply packet that means the previous
	//transactions are finished.
	ReceiveDone = TRUE;
	break;

	//Send empty buffer
	default :
	SendNotSupported();
	break;
	}
	} while (ReceiveDone == FALSE);

	RetCode = GdbParseFReplyPacket (Packet, &ErrNo);
	Print ((CHAR16 *)L"RetCode: %x..ErrNo: %x..\n", RetCode, ErrNo);

	if (ErrNo > 0) {
	//Send error to the host if there is any.
	SendError ((UINT8)ErrNo);
	}

	gProcessingFPacket = FALSE;

	return RetCode;
	}


	/**
	Write data to a FileDescriptor. On success number of bytes written is returned. Zero indicates
	nothing was written. On error -1 is returned.

	@param FileDescriptor Device to talk to.
	@param Buffer Buffer to hold Count bytes that are to be written
	@param Count Number of bytes to transfer.

	@retval -1 Error
	@retval {other} Number of bytes written.

	**/
	INTN
	GdbWrite (
	IN INTN FileDescriptor,
	OUT CONST VOID *Buffer,
	IN UINTN Count
	)
	{
	CHAR8 Packet[128];
	UINTN Size;
	INTN RetCode;
	UINTN ErrNo;
	BOOLEAN ReceiveDone = FALSE;

	// Send:
	// #Fwrite,XX,YYYYYYYY,XX$SS
	//
	// XX - FileDescriptor in ASCII
	// YYYYYYYY - Buffer address in ASCII
	// XX - Count in ASCII
	// SS - check sum
	//
	Size = AsciiSPrint (Packet, sizeof (Packet), "Fwrite,%x,%x,%x", FileDescriptor, Buffer, Count);
	// Packet array is too small if you got this ASSERT
	ASSERT (Size < sizeof (Packet));

	SendPacket (Packet);
	Print ((CHAR16 *)L"Packet sent..\n");

	do {
	// Reply:
	ReceivePacket (Packet, sizeof (Packet));
	Print ((CHAR16 *)L"Command received..%c\n", Packet[0]);

	// Process GDB commands
	switch (Packet[0]) {
	//Read memory command.
	//m addr,length.
	case 'm':
	ReadFromMemory (Packet);
	break;

	//Fretcode, errno, Ctrl-C flag
	//retcode - Count read
	case 'F':
	//Once target receives F reply packet that means the previous
	//transactions are finished.
	ReceiveDone = TRUE;
	break;

	//Send empty buffer
	default :
	SendNotSupported();
	break;
	}
	} while (ReceiveDone == FALSE);

	RetCode = GdbParseFReplyPacket (Packet, &ErrNo);
	Print ((CHAR16 *)L"RetCode: %x..ErrNo: %x..\n", RetCode, ErrNo);

	//Send error to the host if there is any.
	if (ErrNo > 0) {
	SendError((UINT8)ErrNo);
	}

	return RetCode;
	}


	/**
	Reset the serial device.

	@param This Protocol instance pointer.

	@retval EFI_SUCCESS The device was reset.
	@retval EFI_DEVICE_ERROR The serial device could not be reset.

	**/
	EFI_STATUS
	EFIAPI
	GdbSerialReset (
	IN EFI_SERIAL_IO_PROTOCOL *This
	)
	{
	return EFI_SUCCESS;
	}


	/**
	Sets the baud rate, receive FIFO depth, transmit/receice time out, parity,
	data buts, and stop bits on a serial device.

	@param This Protocol instance pointer.
	@param BaudRate The requested baud rate. A BaudRate value of 0 will use the the
	device's default interface speed.
	@param ReveiveFifoDepth The requested depth of the FIFO on the receive side of the
	serial interface. A ReceiveFifoDepth value of 0 will use
	the device's dfault FIFO depth.
	@param Timeout The requested time out for a single character in microseconds.
	This timeout applies to both the transmit and receive side of the
	interface. A Timeout value of 0 will use the device's default time
	out value.
	@param Parity The type of parity to use on this serial device. A Parity value of
	DefaultParity will use the device's default parity value.
	@param DataBits The number of data bits to use on the serial device. A DataBits
	vaule of 0 will use the device's default data bit setting.
	@param StopBits The number of stop bits to use on this serial device. A StopBits
	value of DefaultStopBits will use the device's default number of
	stop bits.

	@retval EFI_SUCCESS The device was reset.
	@retval EFI_DEVICE_ERROR The serial device could not be reset.

	**/
	EFI_STATUS
	EFIAPI
	GdbSerialSetAttributes (
	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
	)
	{
	return EFI_UNSUPPORTED;
	}


	/**
	Set the control bits on a serial device

	@param This Protocol instance pointer.
	@param Control Set the bits of Control that are settable.

	@retval EFI_SUCCESS The new control bits were set on the serial device.
	@retval EFI_UNSUPPORTED The serial device does not support this operation.
	@retval EFI_DEVICE_ERROR The serial device is not functioning correctly.

	**/
	EFI_STATUS
	EFIAPI
	GdbSerialSetControl (
	IN EFI_SERIAL_IO_PROTOCOL *This,
	IN UINT32 Control
	)
	{
	return EFI_UNSUPPORTED;
	}


	/**
	Retrieves the status of thecontrol bits on a serial device

	@param This Protocol instance pointer.
	@param Control A pointer to return the current Control signals from the serial device.

	@retval EFI_SUCCESS The control bits were read from the serial device.
	@retval EFI_DEVICE_ERROR The serial device is not functioning correctly.

	**/
	EFI_STATUS
	EFIAPI
	GdbSerialGetControl (
	IN EFI_SERIAL_IO_PROTOCOL *This,
	OUT UINT32 *Control
	)
	{
	return EFI_UNSUPPORTED;
	}


	/**
	Writes data to a serial device.

	@param This Protocol instance pointer.
	@param BufferSize On input, the size of the Buffer. On output, the amount of
	data actually written.
	@param Buffer The buffer of data to write

	@retval EFI_SUCCESS The data was written.
	@retval EFI_DEVICE_ERROR The device reported an error.
	@retval EFI_TIMEOUT The data write was stopped due to a timeout.

	**/
	EFI_STATUS
	EFIAPI
	GdbSerialWrite (
	IN EFI_SERIAL_IO_PROTOCOL *This,
	IN OUT UINTN *BufferSize,
	IN VOID *Buffer
	)
	{
	GDB_SERIAL_DEV *SerialDev;
	UINTN Return;

	SerialDev = GDB_SERIAL_DEV_FROM_THIS (This);

	Return = GdbWrite (SerialDev->OutFileDescriptor, Buffer, *BufferSize);
	if (Return == (UINTN)-1) {
	return EFI_DEVICE_ERROR;
	}

	if (Return != *BufferSize) {
	*BufferSize = Return;
	}

	return EFI_SUCCESS;
	}

	/**
	Writes data to a serial device.

	@param This Protocol instance pointer.
	@param BufferSize On input, the size of the Buffer. On output, the amount of
	data returned in Buffer.
	@param Buffer The buffer to return the data into.

	@retval EFI_SUCCESS The data was read.
	@retval EFI_DEVICE_ERROR The device reported an error.
	@retval EFI_TIMEOUT The data write was stopped due to a timeout.

	**/

	EFI_STATUS
	EFIAPI
	GdbSerialRead (
	IN EFI_SERIAL_IO_PROTOCOL *This,
	IN OUT UINTN *BufferSize,
	OUT VOID *Buffer
	)
	{
	GDB_SERIAL_DEV *SerialDev;
	UINTN Return;

	SerialDev = GDB_SERIAL_DEV_FROM_THIS (This);

	Return = GdbRead (SerialDev->InFileDescriptor, Buffer, *BufferSize);
	if (Return == (UINTN)-1) {
	return EFI_DEVICE_ERROR;
	}

	if (Return != *BufferSize) {
	*BufferSize = Return;
	}

	return EFI_SUCCESS;
	}


	//
	// Template used to initailize the GDB Serial IO protocols
	//
	GDB_SERIAL_DEV gdbSerialDevTemplate = {
	GDB_SERIAL_DEV_SIGNATURE,
	NULL,

	{ // SerialIo
	SERIAL_IO_INTERFACE_REVISION,
	GdbSerialReset,
	GdbSerialSetAttributes,
	GdbSerialSetControl,
	GdbSerialGetControl,
	GdbSerialWrite,
	GdbSerialRead,
	NULL
	},
	{ // SerialMode
	0, // ControlMask
	0, // Timeout
	0, // BaudRate
	1, // RceiveFifoDepth
	0, // DataBits
	0, // Parity
	0 // StopBits
	},
	{
	{
	{
	HARDWARE_DEVICE_PATH,
	HW_VENDOR_DP,
	{
	(UINT8) (sizeof (VENDOR_DEVICE_PATH) + sizeof (UINT32)),
	(UINT8) ((sizeof (VENDOR_DEVICE_PATH) + sizeof (UINT32)) >> 8)
	},
	},
	EFI_SERIAL_IO_PROTOCOL_GUID
	},
	0,
	{
	END_DEVICE_PATH_TYPE,
	END_ENTIRE_DEVICE_PATH_SUBTYPE,
	{
	(UINT8) (sizeof (EFI_DEVICE_PATH_PROTOCOL)),
	(UINT8) (sizeof (EFI_DEVICE_PATH_PROTOCOL) >> 8)
	}
	},
	},
	GDB_STDIN,
	GDB_STDOUT
	};


	/**
	Make two serial consoles: 1) StdIn and StdOut via GDB. 2) StdErr via GDB.

	These console show up on the remote system running GDB

	**/
	VOID
	GdbInitializeSerialConsole (
	VOID
	)
	{
	EFI_STATUS Status;
	GDB_SERIAL_DEV *StdOutSerialDev;
	GDB_SERIAL_DEV *StdErrSerialDev;

	// Use the template to make a copy of the Serial Console private data structure.
	StdOutSerialDev = AllocateCopyPool (sizeof (GDB_SERIAL_DEV), &gdbSerialDevTemplate);
	ASSERT (StdOutSerialDev != NULL);

	// Fixup pointer after the copy
	StdOutSerialDev->SerialIo.Mode = &StdOutSerialDev->SerialMode;

	StdErrSerialDev = AllocateCopyPool (sizeof (GDB_SERIAL_DEV), &gdbSerialDevTemplate);
	ASSERT (StdErrSerialDev != NULL);

	// Fixup pointer and modify stuff that is different for StdError
	StdErrSerialDev->SerialIo.Mode = &StdErrSerialDev->SerialMode;
	StdErrSerialDev->DevicePath.Index = 1;
	StdErrSerialDev->OutFileDescriptor = GDB_STDERR;

	// Make a new handle with Serial IO protocol and its device path on it.
	Status = gBS->InstallMultipleProtocolInterfaces (
	&StdOutSerialDev->Handle,
	&gEfiSerialIoProtocolGuid, &StdOutSerialDev->SerialIo,
	&gEfiDevicePathProtocolGuid, &StdOutSerialDev->DevicePath,
	NULL
	);
	ASSERT_EFI_ERROR (Status);

	// Make a new handle with Serial IO protocol and its device path on it.
	Status = gBS->InstallMultipleProtocolInterfaces (
	&StdErrSerialDev->Handle,
	&gEfiSerialIoProtocolGuid, &StdErrSerialDev->SerialIo,
	&gEfiDevicePathProtocolGuid, &StdErrSerialDev->DevicePath,
	NULL
	);
	ASSERT_EFI_ERROR (Status);
	}