IntelFrameworkModulePkg/Csm/LegacyBiosDxe/LegacyCmos.c

   1 /** @file
   2   This code fills in standard CMOS values and updates the standard CMOS
   3   checksum. The Legacy16 code or LegacyBiosPlatform.c is responsible for
   4   non-standard CMOS locations and non-standard checksums.
   5
   6 Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
   7
   8 This program and the accompanying materials
   9 are licensed and made available under the terms and conditions
  10 of the BSD License which accompanies this distribution.  The
  11 full text of the license may be found at
  12 http://opensource.org/licenses/bsd-license.php
  13
  14 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  15 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  16
  17 **/
  18
  19 #include "LegacyBiosInterface.h"
  20
  21 /**
  22   Read CMOS register through index/data port.
  23
  24   @param[in]  Index   The index of the CMOS register to read.
  25
  26   @return  The data value from the CMOS register specified by Index.
  27
  28 **/
  29 UINT8
  30 LegacyReadStandardCmos (
  31   IN UINT8  Index
  32   )
  33 {
  34   IoWrite8 (PORT_70, Index);
  35   return IoRead8 (PORT_71);
  36 }
  37
  38 /**
  39   Write CMOS register through index/data port.
  40
  41   @param[in]  Index  The index of the CMOS register to write.
  42   @param[in]  Value  The value of CMOS register to write.
  43
  44   @return  The value written to the CMOS register specified by Index.
  45
  46 **/
  47 UINT8
  48 LegacyWriteStandardCmos (
  49   IN UINT8  Index,
  50   IN UINT8  Value
  51   )
  52 {
  53   IoWrite8 (PORT_70, Index);
  54   return IoWrite8 (PORT_71, Value);
  55 }
  56
  57 /**
  58   Calculate the new standard CMOS checksum and write it.
  59
  60   @param  Private      Legacy BIOS Instance data
  61
  62   @retval EFI_SUCCESS  Calculate 16-bit checksum successfully
  63
  64 **/
  65 EFI_STATUS
  66 LegacyCalculateWriteStandardCmosChecksum (
  67   VOID
  68   )
  69 {
  70   UINT8   Register;
  71   UINT16  Checksum;
  72
  73   for (Checksum = 0, Register = 0x10; Register < 0x2e; Register++) {
  74     Checksum = (UINT16)(Checksum + LegacyReadStandardCmos (Register));
  75   }
  76   LegacyWriteStandardCmos (CMOS_2E, (UINT8)(Checksum >> 8));
  77   LegacyWriteStandardCmos (CMOS_2F, (UINT8)(Checksum & 0xff));
  78   return EFI_SUCCESS;
  79 }
  80
  81
  82 /**
  83   Fill in the standard CMOS stuff before Legacy16 load
  84
  85   @param  Private      Legacy BIOS Instance data
  86
  87   @retval EFI_SUCCESS  It should always work.
  88
  89 **/
  90 EFI_STATUS
  91 LegacyBiosInitCmos (
  92   IN  LEGACY_BIOS_INSTANCE    *Private
  93   )
  94 {
  95   UINT32  Size;
  96
  97   //
  98   //  Clear all errors except RTC lost power
  99   //
 100   LegacyWriteStandardCmos (CMOS_0E, (UINT8)(LegacyReadStandardCmos (CMOS_0E) & BIT7));
 101
 102   //
 103   // Update CMOS locations 15,16,17,18,30,31 and 32
 104   // CMOS 16,15 = 640Kb = 0x280
 105   // CMOS 18,17 = 31,30 = 15Mb max in 1Kb increments =0x3C00 max
 106   // CMOS 32 = 0x20
 107   //
 108   LegacyWriteStandardCmos (CMOS_15, 0x80);
 109   LegacyWriteStandardCmos (CMOS_16, 0x02);
 110
 111   Size = 15 * SIZE_1MB;
 112   if (Private->IntThunk->EfiToLegacy16InitTable.OsMemoryAbove1Mb < (15 * SIZE_1MB)) {
 113     Size  = Private->IntThunk->EfiToLegacy16InitTable.OsMemoryAbove1Mb >> 10;
 114   }
 115
 116   LegacyWriteStandardCmos (CMOS_17, (UINT8)(Size & 0xFF));
 117   LegacyWriteStandardCmos (CMOS_30, (UINT8)(Size & 0xFF));
 118   LegacyWriteStandardCmos (CMOS_18, (UINT8)(Size >> 8));
 119   LegacyWriteStandardCmos (CMOS_31, (UINT8)(Size >> 8));
 120
 121   LegacyCalculateWriteStandardCmosChecksum ();
 122
 123   return EFI_SUCCESS;
 124 }