LXR uboot/common/ddr

   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 */
  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 >= 0x20) {
  24                printf("SPD revision %02X not supported by this code\n",
  25                       spd_rev);
  26                return 1;
  27        }
  28        if (spd_rev > 0x13) {
  29                printf("SPD revision %02X not verified by this code\n",
  30                       spd_rev);
  31        }
  32
  33        /*
  34         * Calculate checksum
  35         */
  36        for (i = 0; i < 63; i++) {
  37                cksum += *buf++;
  38        }
  39        cksum &= 0xFF;
  40
  41        if (cksum != spd_cksum) {
  42                printf("SPD checksum unexpected. "
  43                        "Checksum in SPD = %02X, computed SPD = %02X\n",
  44                        spd_cksum, cksum);
  45                return 1;
  46        }
  47
  48        return 0;
  49}
  50
  51unsigned int
  52ddr1_spd_check(const ddr1_spd_eeprom_t *spd)
  53{
  54        const u8 *p = (const u8 *)spd;
  55
  56        return spd_check(p, spd->spd_rev, spd->cksum);
  57}
  58
  59unsigned int
  60ddr2_spd_check(const ddr2_spd_eeprom_t *spd)
  61{
  62        const u8 *p = (const u8 *)spd;
  63
  64        return spd_check(p, spd->spd_rev, spd->cksum);
  65}
  66
  67/*
  68 * CRC16 compute for DDR3 SPD
  69 * Copied from DDR3 SPD spec.
  70 */
  71static int
  72crc16(char *ptr, int count)
  73{
  74        int crc, i;
  75
  76        crc = 0;
  77        while (--count >= 0) {
  78                crc = crc ^ (int)*ptr++ << 8;
  79                for (i = 0; i < 8; ++i)
  80                        if (crc & 0x8000)
  81                                crc = crc << 1 ^ 0x1021;
  82                        else
  83                                crc = crc << 1;
  84        }
  85        return crc & 0xffff;
  86}
  87
  88unsigned int
  89ddr3_spd_check(const ddr3_spd_eeprom_t *spd)
  90{
  91        char *p = (char *)spd;
  92        int csum16;
  93        int len;
  94        char crc_lsb;   /* byte 126 */
  95        char crc_msb;   /* byte 127 */
  96
  97        /*
  98         * SPD byte0[7] - CRC coverage
  99         * 0 = CRC covers bytes 0~125
 100         * 1 = CRC covers bytes 0~116
 101         */
 102
 103        len = !(spd->info_size_crc & 0x80) ? 126 : 117;
 104        csum16 = crc16(p, len);
 105
 106        crc_lsb = (char) (csum16 & 0xff);
 107        crc_msb = (char) (csum16 >> 8);
 108
 109        if (spd->crc[0] == crc_lsb && spd->crc[1] == crc_msb) {
 110                return 0;
 111        } else {
 112                printf("SPD checksum unexpected.\n"
 113                        "Checksum lsb in SPD = %02X, computed SPD = %02X\n"
 114                        "Checksum msb in SPD = %02X, computed SPD = %02X\n",
 115                        spd->crc[0], crc_lsb, spd->crc[1], crc_msb);
 116                return 1;
 117        }
 118}
 119