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 SPDX-License-Identifier: BSD-2-Clause-Patent
9
10 **/
11
12 #include "LegacyBiosInterface.h"
13
14 /**
15 Read CMOS register through index/data port.
16
17 @param[in] Index The index of the CMOS register to read.
18
19 @return The data value from the CMOS register specified by Index.
20
21 **/
22 UINT8
LegacyReadStandardCmos(IN UINT8 Index)23 LegacyReadStandardCmos (
24 IN UINT8 Index
25 )
26 {
27 IoWrite8 (PORT_70, Index);
28 return IoRead8 (PORT_71);
29 }
30
31 /**
32 Write CMOS register through index/data port.
33
34 @param[in] Index The index of the CMOS register to write.
35 @param[in] Value The value of CMOS register to write.
36
37 @return The value written to the CMOS register specified by Index.
38
39 **/
40 UINT8
LegacyWriteStandardCmos(IN UINT8 Index,IN UINT8 Value)41 LegacyWriteStandardCmos (
42 IN UINT8 Index,
43 IN UINT8 Value
44 )
45 {
46 IoWrite8 (PORT_70, Index);
47 return IoWrite8 (PORT_71, Value);
48 }
49
50 /**
51 Calculate the new standard CMOS checksum and write it.
52
53 @param Private Legacy BIOS Instance data
54
55 @retval EFI_SUCCESS Calculate 16-bit checksum successfully
56
57 **/
58 EFI_STATUS
LegacyCalculateWriteStandardCmosChecksum(VOID)59 LegacyCalculateWriteStandardCmosChecksum (
60 VOID
61 )
62 {
63 UINT8 Register;
64 UINT16 Checksum;
65
66 for (Checksum = 0, Register = 0x10; Register < 0x2e; Register++) {
67 Checksum = (UINT16)(Checksum + LegacyReadStandardCmos (Register));
68 }
69 LegacyWriteStandardCmos (CMOS_2E, (UINT8)(Checksum >> 8));
70 LegacyWriteStandardCmos (CMOS_2F, (UINT8)(Checksum & 0xff));
71 return EFI_SUCCESS;
72 }
73
74
75 /**
76 Fill in the standard CMOS stuff before Legacy16 load
77
78 @param Private Legacy BIOS Instance data
79
80 @retval EFI_SUCCESS It should always work.
81
82 **/
83 EFI_STATUS
LegacyBiosInitCmos(IN LEGACY_BIOS_INSTANCE * Private)84 LegacyBiosInitCmos (
85 IN LEGACY_BIOS_INSTANCE *Private
86 )
87 {
88 UINT32 Size;
89
90 //
91 // Clear all errors except RTC lost power
92 //
93 LegacyWriteStandardCmos (CMOS_0E, (UINT8)(LegacyReadStandardCmos (CMOS_0E) & BIT7));
94
95 //
96 // Update CMOS locations 15,16,17,18,30,31 and 32
97 // CMOS 16,15 = 640Kb = 0x280
98 // CMOS 18,17 = 31,30 = 15Mb max in 1Kb increments =0x3C00 max
99 // CMOS 32 = 0x20
100 //
101 LegacyWriteStandardCmos (CMOS_15, 0x80);
102 LegacyWriteStandardCmos (CMOS_16, 0x02);
103
104 Size = 15 * SIZE_1MB;
105 if (Private->IntThunk->EfiToLegacy16InitTable.OsMemoryAbove1Mb < (15 * SIZE_1MB)) {
106 Size = Private->IntThunk->EfiToLegacy16InitTable.OsMemoryAbove1Mb >> 10;
107 }
108
109 LegacyWriteStandardCmos (CMOS_17, (UINT8)(Size & 0xFF));
110 LegacyWriteStandardCmos (CMOS_30, (UINT8)(Size & 0xFF));
111 LegacyWriteStandardCmos (CMOS_18, (UINT8)(Size >> 8));
112 LegacyWriteStandardCmos (CMOS_31, (UINT8)(Size >> 8));
113
114 LegacyCalculateWriteStandardCmosChecksum ();
115
116 return EFI_SUCCESS;
117 }
118