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/** @file
This code fills in standard CMOS values and updates the standard CMOS
checksum. The Legacy16 code or LegacyBiosPlatform.c is responsible for
non-standard CMOS locations and non-standard checksums.
Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include "LegacyBiosInterface.h"
/**
Read CMOS register through index/data port.
@param[in] Index The index of the CMOS register to read.
@return The data value from the CMOS register specified by Index.
**/
UINT8
LegacyReadStandardCmos (
IN UINT8 Index
)
{
IoWrite8 (PORT_70, Index);
return IoRead8 (PORT_71);
}
/**
Write CMOS register through index/data port.
@param[in] Index The index of the CMOS register to write.
@param[in] Value The value of CMOS register to write.
@return The value written to the CMOS register specified by Index.
**/
UINT8
LegacyWriteStandardCmos (
IN UINT8 Index,
IN UINT8 Value
)
{
IoWrite8 (PORT_70, Index);
return IoWrite8 (PORT_71, Value);
}
/**
Calculate the new standard CMOS checksum and write it.
@param Private Legacy BIOS Instance data
@retval EFI_SUCCESS Calculate 16-bit checksum successfully
**/
EFI_STATUS
LegacyCalculateWriteStandardCmosChecksum (
VOID
)
{
UINT8 Register;
UINT16 Checksum;
for (Checksum = 0, Register = 0x10; Register < 0x2e; Register++) {
Checksum = (UINT16)(Checksum + LegacyReadStandardCmos (Register));
}
LegacyWriteStandardCmos (CMOS_2E, (UINT8)(Checksum >> 8));
LegacyWriteStandardCmos (CMOS_2F, (UINT8)(Checksum & 0xff));
return EFI_SUCCESS;
}
/**
Fill in the standard CMOS stuff before Legacy16 load
@param Private Legacy BIOS Instance data
@retval EFI_SUCCESS It should always work.
**/
EFI_STATUS
LegacyBiosInitCmos (
IN LEGACY_BIOS_INSTANCE *Private
)
{
UINT32 Size;
//
// Clear all errors except RTC lost power
//
LegacyWriteStandardCmos (CMOS_0E, (UINT8)(LegacyReadStandardCmos (CMOS_0E) & BIT7));
//
// Update CMOS locations 15,16,17,18,30,31 and 32
// CMOS 16,15 = 640Kb = 0x280
// CMOS 18,17 = 31,30 = 15Mb max in 1Kb increments =0x3C00 max
// CMOS 32 = 0x20
//
LegacyWriteStandardCmos (CMOS_15, 0x80);
LegacyWriteStandardCmos (CMOS_16, 0x02);
Size = 15 * SIZE_1MB;
if (Private->IntThunk->EfiToLegacy16InitTable.OsMemoryAbove1Mb < (15 * SIZE_1MB)) {
Size = Private->IntThunk->EfiToLegacy16InitTable.OsMemoryAbove1Mb >> 10;
}
LegacyWriteStandardCmos (CMOS_17, (UINT8)(Size & 0xFF));
LegacyWriteStandardCmos (CMOS_30, (UINT8)(Size & 0xFF));
LegacyWriteStandardCmos (CMOS_18, (UINT8)(Size >> 8));
LegacyWriteStandardCmos (CMOS_31, (UINT8)(Size >> 8));
LegacyCalculateWriteStandardCmosChecksum ();
return EFI_SUCCESS;
}
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