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
  12 #include "Cmos.h"
  13 #include "Library/IoLib.h"
  14
  15 /**
  16   Reads 8-bits of CMOS data.
  17
  18   Reads the 8-bits of CMOS data at the location specified by Index.
  19   The 8-bit read value is returned.
  20
  21   @param  Index  The CMOS location to read.
  22
  23   @return The value read.
  24
  25 **/
  26 UINT8
  27 EFIAPI
  28 CmosRead8 (
  29   IN      UINTN                     Index
  30   )
  31 {
  32   IoWrite8 (0x70, (UINT8) Index);
  33   return IoRead8 (0x71);
  34 }
  35
  36
  37 /**
  38   Writes 8-bits of CMOS data.
  39
  40   Writes 8-bits of CMOS data to the location specified by Index
  41   with the value specified by Value and returns Value.
  42
  43   @param  Index  The CMOS location to write.
  44   @param  Value  The value to write to CMOS.
  45
  46   @return The value written to CMOS.
  47
  48 **/
  49 UINT8
  50 EFIAPI
  51 CmosWrite8 (
  52   IN      UINTN                     Index,
  53   IN      UINT8                     Value
  54   )
  55 {
  56   IoWrite8 (0x70, (UINT8) Index);
  57   IoWrite8 (0x71, Value);
  58   return Value;
  59 }
  60