source: vbox/trunk/src/VBox/Devices/EFI/Firmware/OvmfPkg/XenPlatformPei/Cmos.c

/** @file
  PC/AT CMOS access routines

  Copyright (c) 2006 - 2009, Intel Corporation. All rights reserved.<BR>
  Copyright (c) 2019, Citrix Systems, Inc.

  SPDX-License-Identifier: BSD-2-Clause-Patent

**/

#include "Cmos.h"
#include "Library/IoLib.h"

/**
  Reads 8-bits of CMOS data.

  Reads the 8-bits of CMOS data at the location specified by Index.
  The 8-bit read value is returned.

  @param  Index  The CMOS location to read.

  @return The value read.

**/
UINT8
EFIAPI
CmosRead8 (
  IN      UINTN  Index
  )
{
  IoWrite8 (0x70, (UINT8)Index);
  return IoRead8 (0x71);
}

/**
  Writes 8-bits of CMOS data.

  Writes 8-bits of CMOS data to the location specified by Index
  with the value specified by Value and returns Value.

  @param  Index  The CMOS location to write.
  @param  Value  The value to write to CMOS.

  @return The value written to CMOS.

**/
UINT8
EFIAPI
CmosWrite8 (
  IN      UINTN  Index,
  IN      UINT8  Value
  )
{
  IoWrite8 (0x70, (UINT8)Index);
  IoWrite8 (0x71, Value);
  return Value;
}