OvmfPkg/PlatformPei/Cmos.c

   1 /** @file
   2   PC/AT CMOS access routines
   3
   4   Copyright (c) 2006 - 2009, Intel Corporation. All rights reserved.<BR>
   5   This program and the accompanying materials
   6   are licensed and made available under the terms and conditions of the BSD License
   7   which accompanies this distribution.  The full text of the license may be found at
   8   http://opensource.org/licenses/bsd-license.php
   9
  10   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13 **/
  14
  15
  16 #include "Cmos.h"
  17 #include "Library/IoLib.h"
  18
  19 /**
  20   Reads 8-bits of CMOS data.
  21
  22   Reads the 8-bits of CMOS data at the location specified by Index.
  23   The 8-bit read value is returned.
  24
  25   @param  Index  The CMOS location to read.
  26
  27   @return The value read.
  28
  29 **/
  30 UINT8
  31 EFIAPI
  32 CmosRead8 (
  33   IN      UINTN                     Index
  34   )
  35 {
  36   IoWrite8 (0x70, (UINT8) Index);
  37   return IoRead8 (0x71);
  38 }
  39
  40
  41 /**
  42   Writes 8-bits of CMOS data.
  43
  44   Writes 8-bits of CMOS data to the location specified by Index
  45   with the value specified by Value and returns Value.
  46
  47   @param  Index  The CMOS location to write.
  48   @param  Value  The value to write to CMOS.
  49
  50   @return The value written to CMOS.
  51
  52 **/
  53 UINT8
  54 EFIAPI
  55 CmosWrite8 (
  56   IN      UINTN                     Index,
  57   IN      UINT8                     Value
  58   )
  59 {
  60   IoWrite8 (0x70, (UINT8) Index);
  61   IoWrite8 (0x71, Value);
  62   return Value;
  63 }
  64