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0f2cbe3f JY |
1 | /* |
2 | * Copyright 2008 Freescale Semiconductor, Inc. | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or | |
5 | * modify it under the terms of the GNU General Public License | |
6 | * Version 2 as published by the Free Software Foundation. | |
7 | */ | |
8 | ||
9 | #include <common.h> | |
10 | #include <ddr_spd.h> | |
11 | ||
12 | /* used for ddr1 and ddr2 spd */ | |
13 | static int | |
14 | spd_check(const u8 *buf, u8 spd_rev, u8 spd_cksum) | |
15 | { | |
16 | unsigned int cksum = 0; | |
17 | unsigned int i; | |
18 | ||
19 | /* | |
20 | * Check SPD revision supported | |
21 | * Rev 1.2 or less supported by this code | |
22 | */ | |
23 | if (spd_rev > 0x12) { | |
24 | printf("SPD revision %02X not supported by this code\n", | |
25 | spd_rev); | |
26 | return 1; | |
27 | } | |
28 | ||
29 | /* | |
30 | * Calculate checksum | |
31 | */ | |
32 | for (i = 0; i < 63; i++) { | |
33 | cksum += *buf++; | |
34 | } | |
35 | cksum &= 0xFF; | |
36 | ||
37 | if (cksum != spd_cksum) { | |
38 | printf("SPD checksum unexpected. " | |
39 | "Checksum in SPD = %02X, computed SPD = %02X\n", | |
40 | spd_cksum, cksum); | |
41 | return 1; | |
42 | } | |
43 | ||
44 | return 0; | |
45 | } | |
46 | ||
47 | unsigned int | |
48 | ddr1_spd_check(const ddr1_spd_eeprom_t *spd) | |
49 | { | |
50 | const u8 *p = (const u8 *)spd; | |
51 | ||
52 | return spd_check(p, spd->spd_rev, spd->cksum); | |
53 | } | |
54 | ||
55 | unsigned int | |
56 | ddr2_spd_check(const ddr2_spd_eeprom_t *spd) | |
57 | { | |
58 | const u8 *p = (const u8 *)spd; | |
59 | ||
60 | return spd_check(p, spd->spd_rev, spd->cksum); | |
61 | } | |
c360ceac DL |
62 | |
63 | /* | |
64 | * CRC16 compute for DDR3 SPD | |
65 | * Copied from DDR3 SPD spec. | |
66 | */ | |
67 | static int | |
68 | crc16(char *ptr, int count) | |
69 | { | |
70 | int crc, i; | |
71 | ||
72 | crc = 0; | |
73 | while (--count >= 0) { | |
74 | crc = crc ^ (int)*ptr++ << 8; | |
75 | for (i = 0; i < 8; ++i) | |
76 | if (crc & 0x8000) | |
77 | crc = crc << 1 ^ 0x1021; | |
78 | else | |
79 | crc = crc << 1; | |
80 | } | |
81 | return crc & 0xffff; | |
82 | } | |
83 | ||
84 | unsigned int | |
85 | ddr3_spd_check(const ddr3_spd_eeprom_t *spd) | |
86 | { | |
87 | char *p = (char *)spd; | |
88 | int csum16; | |
89 | int len; | |
90 | char crc_lsb; /* byte 126 */ | |
91 | char crc_msb; /* byte 127 */ | |
92 | ||
93 | /* | |
94 | * SPD byte0[7] - CRC coverage | |
95 | * 0 = CRC covers bytes 0~125 | |
96 | * 1 = CRC covers bytes 0~116 | |
97 | */ | |
98 | ||
99 | len = !(spd->info_size_crc & 0x80) ? 126 : 117; | |
100 | csum16 = crc16(p, len); | |
101 | ||
102 | crc_lsb = (char) (csum16 & 0xff); | |
103 | crc_msb = (char) (csum16 >> 8); | |
104 | ||
105 | if (spd->crc[0] == crc_lsb && spd->crc[1] == crc_msb) { | |
106 | return 0; | |
107 | } else { | |
108 | printf("SPD checksum unexpected.\n" | |
109 | "Checksum lsb in SPD = %02X, computed SPD = %02X\n" | |
110 | "Checksum msb in SPD = %02X, computed SPD = %02X\n", | |
111 | spd->crc[0], crc_lsb, spd->crc[1], crc_msb); | |
112 | return 1; | |
113 | } | |
114 | } |