common/ddr_spd.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright 2008-2014 Freescale Semiconductor, Inc.
   4  */
   5
   6 #include <common.h>
   7 #include <ddr_spd.h>
   8
   9 /* used for ddr1 and ddr2 spd */
  10 static int
  11 spd_check(const u8 *buf, u8 spd_rev, u8 spd_cksum)
  12 {
  13         unsigned int cksum = 0;
  14         unsigned int i;
  15
  16         /*
  17          * Check SPD revision supported
  18          * Rev 1.X or less supported by this code
  19          */
  20         if (spd_rev >= 0x20) {
  21                 printf("SPD revision %02X not supported by this code\n",
  22                        spd_rev);
  23                 return 1;
  24         }
  25         if (spd_rev > 0x13) {
  26                 printf("SPD revision %02X not verified by this code\n",
  27                        spd_rev);
  28         }
  29
  30         /*
  31          * Calculate checksum
  32          */
  33         for (i = 0; i < 63; i++) {
  34                 cksum += *buf++;
  35         }
  36         cksum &= 0xFF;
  37
  38         if (cksum != spd_cksum) {
  39                 printf("SPD checksum unexpected. "
  40                         "Checksum in SPD = %02X, computed SPD = %02X\n",
  41                         spd_cksum, cksum);
  42                 return 1;
  43         }
  44
  45         return 0;
  46 }
  47
  48 unsigned int
  49 ddr1_spd_check(const ddr1_spd_eeprom_t *spd)
  50 {
  51         const u8 *p = (const u8 *)spd;
  52
  53         return spd_check(p, spd->spd_rev, spd->cksum);
  54 }
  55
  56 unsigned int
  57 ddr2_spd_check(const ddr2_spd_eeprom_t *spd)
  58 {
  59         const u8 *p = (const u8 *)spd;
  60
  61         return spd_check(p, spd->spd_rev, spd->cksum);
  62 }
  63
  64 /*
  65  * CRC16 compute for DDR3 SPD
  66  * Copied from DDR3 SPD spec.
  67  */
  68 static int
  69 crc16(char *ptr, int count)
  70 {
  71         int crc, i;
  72
  73         crc = 0;
  74         while (--count >= 0) {
  75                 crc = crc ^ (int)*ptr++ << 8;
  76                 for (i = 0; i < 8; ++i)
  77                         if (crc & 0x8000)
  78                                 crc = crc << 1 ^ 0x1021;
  79                         else
  80                                 crc = crc << 1;
  81         }
  82         return crc & 0xffff;
  83 }
  84
  85 unsigned int
  86 ddr3_spd_check(const ddr3_spd_eeprom_t *spd)
  87 {
  88         char *p = (char *)spd;
  89         int csum16;
  90         int len;
  91         char crc_lsb;   /* byte 126 */
  92         char crc_msb;   /* byte 127 */
  93
  94         /*
  95          * SPD byte0[7] - CRC coverage
  96          * 0 = CRC covers bytes 0~125
  97          * 1 = CRC covers bytes 0~116
  98          */
  99
 100         len = !(spd->info_size_crc & 0x80) ? 126 : 117;
 101         csum16 = crc16(p, len);
 102
 103         crc_lsb = (char) (csum16 & 0xff);
 104         crc_msb = (char) (csum16 >> 8);
 105
 106         if (spd->crc[0] == crc_lsb && spd->crc[1] == crc_msb) {
 107                 return 0;
 108         } else {
 109                 printf("SPD checksum unexpected.\n"
 110                         "Checksum lsb in SPD = %02X, computed SPD = %02X\n"
 111                         "Checksum msb in SPD = %02X, computed SPD = %02X\n",
 112                         spd->crc[0], crc_lsb, spd->crc[1], crc_msb);
 113                 return 1;
 114         }
 115 }
 116
 117 unsigned int ddr4_spd_check(const struct ddr4_spd_eeprom_s *spd)
 118 {
 119         char *p = (char *)spd;
 120         int csum16;
 121         int len;
 122         char crc_lsb;   /* byte 126 */
 123         char crc_msb;   /* byte 127 */
 124
 125         len = 126;
 126         csum16 = crc16(p, len);
 127
 128         crc_lsb = (char) (csum16 & 0xff);
 129         crc_msb = (char) (csum16 >> 8);
 130
 131         if (spd->crc[0] != crc_lsb || spd->crc[1] != crc_msb) {
 132                 printf("SPD checksum unexpected.\n"
 133                         "Checksum lsb in SPD = %02X, computed SPD = %02X\n"
 134                         "Checksum msb in SPD = %02X, computed SPD = %02X\n",
 135                         spd->crc[0], crc_lsb, spd->crc[1], crc_msb);
 136                 return 1;
 137         }
 138
 139         p = (char *)((ulong)spd + 128);
 140         len = 126;
 141         csum16 = crc16(p, len);
 142
 143         crc_lsb = (char) (csum16 & 0xff);
 144         crc_msb = (char) (csum16 >> 8);
 145
 146         if (spd->mod_section.uc[126] != crc_lsb ||
 147             spd->mod_section.uc[127] != crc_msb) {
 148                 printf("SPD checksum unexpected.\n"
 149                         "Checksum lsb in SPD = %02X, computed SPD = %02X\n"
 150                         "Checksum msb in SPD = %02X, computed SPD = %02X\n",
 151                         spd->mod_section.uc[126],
 152                         crc_lsb, spd->mod_section.uc[127],
 153                         crc_msb);
 154                 return 1;
 155         }
 156
 157         return 0;
 158 }