hw/block/ecc.c

   1 /*
   2  * Calculate Error-correcting Codes. Used by NAND Flash controllers
   3  * (not by NAND chips).
   4  *
   5  * Copyright (c) 2006 Openedhand Ltd.
   6  * Written by Andrzej Zaborowski <balrog@zabor.org>
   7  *
   8  * This code is licensed under the GNU GPL v2.
   9  *
  10  * Contributions after 2012-01-13 are licensed under the terms of the
  11  * GNU GPL, version 2 or (at your option) any later version.
  12  */
  13
  14 #include "qemu/osdep.h"
  15 #include "hw/hw.h"
  16 #include "hw/block/flash.h"
  17
  18 /*
  19  * Pre-calculated 256-way 1 byte column parity.  Table borrowed from Linux.
  20  */
  21 static const uint8_t nand_ecc_precalc_table[] = {
  22     0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a,
  23     0x5a, 0x0f, 0x0c, 0x59, 0x03, 0x56, 0x55, 0x00,
  24     0x65, 0x30, 0x33, 0x66, 0x3c, 0x69, 0x6a, 0x3f,
  25     0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65,
  26     0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c,
  27     0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66,
  28     0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59,
  29     0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03,
  30     0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65, 0x66, 0x33,
  31     0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69,
  32     0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56,
  33     0x56, 0x03, 0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c,
  34     0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03, 0x00, 0x55,
  35     0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f,
  36     0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30,
  37     0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a,
  38     0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30,
  39     0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a,
  40     0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03, 0x00, 0x55,
  41     0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f,
  42     0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56,
  43     0x56, 0x03, 0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c,
  44     0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65, 0x66, 0x33,
  45     0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69,
  46     0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59,
  47     0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03,
  48     0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c,
  49     0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66,
  50     0x65, 0x30, 0x33, 0x66, 0x3c, 0x69, 0x6a, 0x3f,
  51     0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65,
  52     0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a,
  53     0x5a, 0x0f, 0x0c, 0x59, 0x03, 0x56, 0x55, 0x00,
  54 };
  55
  56 /* Update ECC parity count.  */
  57 uint8_t ecc_digest(ECCState *s, uint8_t sample)
  58 {
  59     uint8_t idx = nand_ecc_precalc_table[sample];
  60
  61     s->cp ^= idx & 0x3f;
  62     if (idx & 0x40) {
  63         s->lp[0] ^= ~s->count;
  64         s->lp[1] ^= s->count;
  65     }
  66     s->count ++;
  67
  68     return sample;
  69 }
  70
  71 /* Reinitialise the counters.  */
  72 void ecc_reset(ECCState *s)
  73 {
  74     s->lp[0] = 0x0000;
  75     s->lp[1] = 0x0000;
  76     s->cp = 0x00;
  77     s->count = 0;
  78 }
  79
  80 /* Save/restore */
  81 VMStateDescription vmstate_ecc_state = {
  82     .name = "ecc-state",
  83     .version_id = 0,
  84     .minimum_version_id = 0,
  85     .fields = (VMStateField[]) {
  86         VMSTATE_UINT8(cp, ECCState),
  87         VMSTATE_UINT16_ARRAY(lp, ECCState, 2),
  88         VMSTATE_UINT16(count, ECCState),
  89         VMSTATE_END_OF_LIST(),
  90     },
  91 };