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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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