OvmfPkg/XenPlatformPei/Cmos.c

   1 /** @file
   2   PC/AT CMOS access routines
   3
   4   Copyright (c) 2006 - 2009, Intel Corporation. All rights reserved.<BR>
   5   Copyright (c) 2019, Citrix Systems, Inc.
   6
   7   SPDX-License-Identifier: BSD-2-Clause-Patent
   8
   9 **/
  10
  11 #include "Cmos.h"
  12 #include "Library/IoLib.h"
  13
  14 /**
  15   Reads 8-bits of CMOS data.
  16
  17   Reads the 8-bits of CMOS data at the location specified by Index.
  18   The 8-bit read value is returned.
  19
  20   @param  Index  The CMOS location to read.
  21
  22   @return The value read.
  23
  24 **/
  25 UINT8
  26 EFIAPI
  27 CmosRead8 (
  28   IN      UINTN  Index
  29   )
  30 {
  31   IoWrite8 (0x70, (UINT8)Index);
  32   return IoRead8 (0x71);
  33 }
  34
  35 /**
  36   Writes 8-bits of CMOS data.
  37
  38   Writes 8-bits of CMOS data to the location specified by Index
  39   with the value specified by Value and returns Value.
  40
  41   @param  Index  The CMOS location to write.
  42   @param  Value  The value to write to CMOS.
  43
  44   @return The value written to CMOS.
  45
  46 **/
  47 UINT8
  48 EFIAPI
  49 CmosWrite8 (
  50   IN      UINTN  Index,
  51   IN      UINT8  Value
  52   )
  53 {
  54   IoWrite8 (0x70, (UINT8)Index);
  55   IoWrite8 (0x71, Value);
  56   return Value;
  57 }