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/*
* Copyright 2008 Freescale Semiconductor, Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* Version 2 as published by the Free Software Foundation.
*/
#include <common.h>
#include <ddr_spd.h>
/* used for ddr1 and ddr2 spd */
static int
spd_check(const u8 *buf, u8 spd_rev, u8 spd_cksum)
{
unsigned int cksum = 0;
unsigned int i;
/*
* Check SPD revision supported
* Rev 1.2 or less supported by this code
*/
if (spd_rev > 0x12) {
printf("SPD revision %02X not supported by this code\n",
spd_rev);
return 1;
}
/*
* Calculate checksum
*/
for (i = 0; i < 63; i++) {
cksum += *buf++;
}
cksum &= 0xFF;
if (cksum != spd_cksum) {
printf("SPD checksum unexpected. "
"Checksum in SPD = %02X, computed SPD = %02X\n",
spd_cksum, cksum);
return 1;
}
return 0;
}
unsigned int
ddr1_spd_check(const ddr1_spd_eeprom_t *spd)
{
const u8 *p = (const u8 *)spd;
return spd_check(p, spd->spd_rev, spd->cksum);
}
unsigned int
ddr2_spd_check(const ddr2_spd_eeprom_t *spd)
{
const u8 *p = (const u8 *)spd;
return spd_check(p, spd->spd_rev, spd->cksum);
}
/*
* CRC16 compute for DDR3 SPD
* Copied from DDR3 SPD spec.
*/
static int
crc16(char *ptr, int count)
{
int crc, i;
crc = 0;
while (--count >= 0) {
crc = crc ^ (int)*ptr++ << 8;
for (i = 0; i < 8; ++i)
if (crc & 0x8000)
crc = crc << 1 ^ 0x1021;
else
crc = crc << 1;
}
return crc & 0xffff;
}
unsigned int
ddr3_spd_check(const ddr3_spd_eeprom_t *spd)
{
char *p = (char *)spd;
int csum16;
int len;
char crc_lsb; /* byte 126 */
char crc_msb; /* byte 127 */
/*
* SPD byte0[7] - CRC coverage
* 0 = CRC covers bytes 0~125
* 1 = CRC covers bytes 0~116
*/
len = !(spd->info_size_crc & 0x80) ? 126 : 117;
csum16 = crc16(p, len);
crc_lsb = (char) (csum16 & 0xff);
crc_msb = (char) (csum16 >> 8);
if (spd->crc[0] == crc_lsb && spd->crc[1] == crc_msb) {
return 0;
} else {
printf("SPD checksum unexpected.\n"
"Checksum lsb in SPD = %02X, computed SPD = %02X\n"
"Checksum msb in SPD = %02X, computed SPD = %02X\n",
spd->crc[0], crc_lsb, spd->crc[1], crc_msb);
return 1;
}
}
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