audk/Vlv2TbltDevicePkg/Library/SerialPortLib/SerialPortLib.c

/** @file
  Serial I/O Port library functions with no library constructor/destructor

  Copyright (c) 2006 - 2017, Intel Corporation. All rights reserved.<BR>
                                                                                   
  SPDX-License-Identifier: BSD-2-Clause-Patent

**/

#include "PlatformSerialPortLib.h"

UINT16 gComBase  = 0x3f8;
UINTN  gBps      = 115200;
UINT8  gData     = 8;
UINT8  gStop     = 1;
UINT8  gParity   = 0;
UINT8  gBreakSet = 0;

/**
  Initialize Serial Port

  The Baud Rate Divisor registers are programmed and the LCR
  is used to configure the communications format. Hard coded
  UART config comes from globals in DebugSerialPlatform lib.

  @param None

  @retval None

**/
RETURN_STATUS
EFIAPI
UARTInitialize (
  VOID
  )
{
  UINTN Divisor;
  UINT8 OutputData;
  UINT8 Data;

  //
  // Map 5..8 to 0..3
  //
  Data = (UINT8) (gData - (UINT8) 5);

  //
  // Calculate divisor for baud generator
  //
  Divisor = 115200 / gBps;

  //
  // Set communications format
  //
  OutputData = (UINT8) ((DLAB << 7) | ((gBreakSet << 6) | ((gParity << 3) | ((gStop << 2) | Data))));
  IoWrite8 (gComBase + LCR_OFFSET, OutputData);

  //
  // Configure baud rate
  //
  IoWrite8 (gComBase + BAUD_HIGH_OFFSET, (UINT8) (Divisor >> 8));
  IoWrite8 (gComBase + BAUD_LOW_OFFSET, (UINT8) (Divisor & 0xff));

  //
  // Switch back to bank 0
  //
  OutputData = (UINT8) ((~DLAB << 7) | ((gBreakSet << 6) | ((gParity << 3) | ((gStop << 2) | Data))));
  IoWrite8 (gComBase + LCR_OFFSET, OutputData);

  return RETURN_SUCCESS;
}

/**
  Common function to initialize UART Serial device and USB Serial device.

  @param None

  @retval None

**/
RETURN_STATUS
EFIAPI
SerialPortInitialize (
  VOID
  )
{

  UARTInitialize ();


  return RETURN_SUCCESS;
}

/**
  Write data to serial device.

  If the buffer is NULL, then return 0;
  if NumberOfBytes is zero, then return 0.

  @param  Buffer           Point of data buffer which need to be writed.
  @param  NumberOfBytes    Number of output bytes which are cached in Buffer.

  @retval 0                Write data failed.
  @retval !0               Actual number of bytes writed to serial device.

**/
UINTN
EFIAPI
UARTDbgOut (
  IN UINT8     *Buffer,
  IN UINTN     NumberOfBytes
)
{
  UINTN Result;
  UINT8 Data;

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

  Result = NumberOfBytes;

  while (NumberOfBytes--) {
    //
    // Wait for the serial port to be ready.
    //
    do {
      Data = IoRead8 ((UINT16) PcdGet64 (PcdSerialRegisterBase) + LSR_OFFSET);
    } while ((Data & LSR_TXRDY) == 0);
    IoWrite8 ((UINT16) PcdGet64 (PcdSerialRegisterBase), *Buffer++);
  }

  return Result;
}

/**
  Common function to write data to UART Serial device and USB Serial device.

  @param  Buffer           Point of data buffer which need to be writed.
  @param  NumberOfBytes    Number of output bytes which are cached in Buffer.

**/
UINTN
EFIAPI
SerialPortWrite (
  IN UINT8     *Buffer,
  IN UINTN     NumberOfBytes
)
{
  if (FeaturePcdGet (PcdStatusCodeUseIsaSerial)) {
    UARTDbgOut (Buffer, NumberOfBytes);
  }

  return RETURN_SUCCESS;
}

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

  If the buffer is NULL, then return 0;
  if NumberOfBytes is zero, then return 0.

  @param  Buffer           Point of data buffer which need to be writed.
  @param  NumberOfBytes    Number of output bytes which are cached in Buffer.

  @retval 0                Read data failed.
  @retval !0               Actual number of bytes raed to serial device.

**/
UINTN
EFIAPI
UARTDbgIn (
  OUT UINT8     *Buffer,
  IN  UINTN     NumberOfBytes
)
{
  UINTN Result;
  UINT8 Data;

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

  Result = NumberOfBytes;

  while (NumberOfBytes--) {
    //
    // Wait for the serial port to be ready.
    //
    do {
      Data = IoRead8 ((UINT16) PcdGet64 (PcdSerialRegisterBase) + LSR_OFFSET);
    } while ((Data & LSR_RXDA) == 0);

    *Buffer++ = IoRead8 ((UINT16) PcdGet64 (PcdSerialRegisterBase));
  }

  return Result;
}

/**
  Common function to Read data from UART serial device, USB serial device and save the datas in buffer.

  @param  Buffer           Point of data buffer which need to be writed.
  @param  NumberOfBytes    Number of output bytes which are cached in Buffer.

**/
UINTN
EFIAPI
SerialPortRead (
  OUT UINT8     *Buffer,
  IN  UINTN     NumberOfBytes
)
{
  if (FeaturePcdGet (PcdStatusCodeUseIsaSerial)) {
    UARTDbgIn (Buffer, NumberOfBytes);
  }

  return RETURN_SUCCESS;
}


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

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

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

**/
BOOLEAN
EFIAPI
SerialPortPoll (
  VOID
  )
{
  UINT8  Data;

  //
  // Read the serial port status.
  //
  Data = IoRead8 ((UINT16) PcdGet64 (PcdSerialRegisterBase) + LSR_OFFSET);

  return (BOOLEAN) ((Data & LSR_RXDA) != 0);
}