audk/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c

/** @file

  Copyright (c) 2011 - 2012, Intel Corporation. All rights reserved.<BR>

  This program and the accompanying materials
  are licensed and made available under the terms and conditions of the BSD License
  which accompanies this distribution.  The full text of the license may be found at
  http://opensource.org/licenses/bsd-license.php

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

**/

#include "Uefi.h"
#include <Library/BaseLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/DebugLib.h>
#include <Library/IoLib.h>
#include <Library/QemuFwCfgLib.h>
#include <Library/MemoryAllocationLib.h>
#include <Library/UefiBootServicesTableLib.h>

STATIC BOOLEAN mQemuFwCfgSupported = FALSE;


/**
  Reads an 8-bit I/O port fifo into a block of memory.

  Reads the 8-bit I/O fifo port specified by Port.

  The port is read Count times, and the read data is
  stored in the provided Buffer.

  This function must guarantee that all I/O read and write operations are
  serialized.

  If 8-bit I/O port operations are not supported, then ASSERT().

  @param  Port    The I/O port to read.
  @param  Count   The number of times to read I/O port.
  @param  Buffer  The buffer to store the read data into.

**/
VOID
EFIAPI
IoReadFifo8 (
  IN      UINTN                     Port,
  IN      UINTN                     Count,
  OUT     VOID                      *Buffer
  );


/**
  Returns a boolean indicating if the firmware configuration interface
  is available or not.

  @retval    TRUE   The interface is available
  @retval    FALSE  The interface is not available

**/
BOOLEAN
EFIAPI
QemuFwCfgIsAvailable (
  VOID
  )
{
  return mQemuFwCfgSupported;
}


/**
  Selects a firmware configuration item for reading.
  
  Following this call, any data read from this item will start from
  the beginning of the configuration item's data.

  @param[in] QemuFwCfgItem - Firmware Configuration item to read

**/
VOID
EFIAPI
QemuFwCfgSelectItem (
  IN FIRMWARE_CONFIG_ITEM   QemuFwCfgItem
  )
{
  DEBUG ((EFI_D_INFO, "Select Item: 0x%x\n", (UINT16)(UINTN) QemuFwCfgItem));
  IoWrite16 (0x510, (UINT16)(UINTN) QemuFwCfgItem);
}


/**
  Reads firmware configuration bytes into a buffer

  @param[in] Size - Size in bytes to read
  @param[in] Buffer - Buffer to store data into  (OPTIONAL if Size is 0)

**/
VOID
EFIAPI
InternalQemuFwCfgReadBytes (
  IN UINTN                  Size,
  IN VOID                   *Buffer  OPTIONAL
  )
{
  IoReadFifo8 (0x511, Size, Buffer);
}


/**
  Reads firmware configuration bytes into a buffer

  If called multiple times, then the data read will
  continue at the offset of the firmware configuration
  item where the previous read ended.

  @param[in] Size - Size in bytes to read
  @param[in] Buffer - Buffer to store data into

**/
VOID
EFIAPI
QemuFwCfgReadBytes (
  IN UINTN                  Size,
  IN VOID                   *Buffer
  )
{
  if (mQemuFwCfgSupported) {
    InternalQemuFwCfgReadBytes (Size, Buffer);
  } else {
    ZeroMem (Buffer, Size);
  }
}


/**
  Reads a UINT8 firmware configuration value

  @return    Value of Firmware Configuration item read

**/
UINT8
EFIAPI
QemuFwCfgRead8 (
  VOID
  )
{
  UINT8 Result;

  QemuFwCfgReadBytes (sizeof (Result), &Result);

  return Result;
}


/**
  Reads a UINT16 firmware configuration value

  @return    Value of Firmware Configuration item read

**/
UINT16
EFIAPI
QemuFwCfgRead16 (
  VOID
  )
{
  UINT16 Result;

  QemuFwCfgReadBytes (sizeof (Result), &Result);

  return Result;
}


/**
  Reads a UINT32 firmware configuration value

  @return    Value of Firmware Configuration item read

**/
UINT32
EFIAPI
QemuFwCfgRead32 (
  VOID
  )
{
  UINT32 Result;

  QemuFwCfgReadBytes (sizeof (Result), &Result);

  return Result;
}


/**
  Reads a UINT64 firmware configuration value

  @return    Value of Firmware Configuration item read

**/
UINT64
EFIAPI
QemuFwCfgRead64 (
  VOID
  )
{
  UINT64 Result;

  QemuFwCfgReadBytes (sizeof (Result), &Result);

  return Result;
}


RETURN_STATUS
EFIAPI
QemuFwCfgInitialize (
  VOID
  )
{
  UINT32 Signature;
  UINT32 Revision;

  //
  // Enable the access routines while probing to see if it is supported.
  //
  mQemuFwCfgSupported = TRUE;

  QemuFwCfgSelectItem (QemuFwCfgItemSignature);
  Signature = QemuFwCfgRead32 ();
  DEBUG ((EFI_D_INFO, "FW CFG Signature: 0x%x\n", Signature));
  QemuFwCfgSelectItem (QemuFwCfgItemInterfaceVersion);
  Revision = QemuFwCfgRead32 ();
  DEBUG ((EFI_D_INFO, "FW CFG Revision: 0x%x\n", Revision));
  if ((Signature != SIGNATURE_32 ('Q', 'E', 'M', 'U')) ||
      (Revision < 1)
     ) {
    DEBUG ((EFI_D_INFO, "QemuFwCfg interface not supported.\n"));
    mQemuFwCfgSupported = FALSE;
    return RETURN_SUCCESS;
  }

  DEBUG ((EFI_D_INFO, "QemuFwCfg interface is supported.\n"));
  return RETURN_SUCCESS;
}