blob: c058e4f18a314c9fbc1890591d38bcb53ef0d803 [file] [log] [blame]
James Yang0f2cbe32008-08-26 15:01:27 -05001/*
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 */
13static int
14spd_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
47unsigned int
48ddr1_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
55unsigned int
56ddr2_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}
Dave Liuc360cea2009-03-14 12:48:30 +080062
63/*
64 * CRC16 compute for DDR3 SPD
65 * Copied from DDR3 SPD spec.
66 */
67static int
68crc16(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
84unsigned int
85ddr3_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}