drivers/mtd/nand/nand_ecc.c

   1 /*
   2  * This file contains an ECC algorithm from Toshiba that detects and
   3  * corrects 1 bit errors in a 256 byte block of data.
   4  *
   5  * drivers/mtd/nand/nand_ecc.c
   6  *
   7  * Copyright (C) 2000-2004 Steven J. Hill (sjhill@realitydiluted.com)
   8  *                         Toshiba America Electronics Components, Inc.
   9  *
  10  * Copyright (C) 2006 Thomas Gleixner <tglx@linutronix.de>
  11  *
  12  * $Id: nand_ecc.c,v 1.15 2005/11/07 11:14:30 gleixner Exp $
  13  *
  14  * This file is free software; you can redistribute it and/or modify it
  15  * under the terms of the GNU General Public License as published by the
  16  * Free Software Foundation; either version 2 or (at your option) any
  17  * later version.
  18  *
  19  * This file is distributed in the hope that it will be useful, but WITHOUT
  20  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  21  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  22  * for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License along
  25  * with this file; if not, write to the Free Software Foundation, Inc.,
  26  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  27  *
  28  * As a special exception, if other files instantiate templates or use
  29  * macros or inline functions from these files, or you compile these
  30  * files and link them with other works to produce a work based on these
  31  * files, these files do not by themselves cause the resulting work to be
  32  * covered by the GNU General Public License. However the source code for
  33  * these files must still be made available in accordance with section (3)
  34  * of the GNU General Public License.
  35  *
  36  * This exception does not invalidate any other reasons why a work based on
  37  * this file might be covered by the GNU General Public License.
  38  */
  39
  40 #include <common.h>
  41
  42 /* XXX U-BOOT XXX */
  43 #if 0
  44 #include <linux/types.h>
  45 #include <linux/kernel.h>
  46 #include <linux/module.h>
  47 #include <linux/mtd/nand_ecc.h>
  48 #endif
  49
  50 #include<linux/mtd/mtd.h>
  51
  52 /*
  53  * NAND-SPL has no sofware ECC for now, so don't include nand_calculate_ecc(),
  54  * only nand_correct_data() is needed
  55  */
  56
  57 #ifndef CONFIG_NAND_SPL
  58 /*
  59  * Pre-calculated 256-way 1 byte column parity
  60  */
  61 static const u_char nand_ecc_precalc_table[] = {
  62         0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a, 0x5a, 0x0f, 0x0c, 0x59, 0x03, 0x56, 0x55, 0x00,
  63         0x65, 0x30, 0x33, 0x66, 0x3c, 0x69, 0x6a, 0x3f, 0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65,
  64         0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c, 0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66,
  65         0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59, 0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03,
  66         0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65, 0x66, 0x33, 0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69,
  67         0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56, 0x56, 0x03, 0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c,
  68         0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03, 0x00, 0x55, 0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f,
  69         0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30, 0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a,
  70         0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30, 0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a,
  71         0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03, 0x00, 0x55, 0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f,
  72         0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56, 0x56, 0x03, 0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c,
  73         0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65, 0x66, 0x33, 0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69,
  74         0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59, 0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03,
  75         0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c, 0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66,
  76         0x65, 0x30, 0x33, 0x66, 0x3c, 0x69, 0x6a, 0x3f, 0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65,
  77         0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a, 0x5a, 0x0f, 0x0c, 0x59, 0x03, 0x56, 0x55, 0x00
  78 };
  79
  80 /**
  81  * nand_calculate_ecc - [NAND Interface] Calculate 3-byte ECC for 256-byte block
  82  * @mtd:        MTD block structure
  83  * @dat:        raw data
  84  * @ecc_code:   buffer for ECC
  85  */
  86 int nand_calculate_ecc(struct mtd_info *mtd, const u_char *dat,
  87                        u_char *ecc_code)
  88 {
  89         uint8_t idx, reg1, reg2, reg3, tmp1, tmp2;
  90         int i;
  91
  92         /* Initialize variables */
  93         reg1 = reg2 = reg3 = 0;
  94
  95         /* Build up column parity */
  96         for(i = 0; i < 256; i++) {
  97                 /* Get CP0 - CP5 from table */
  98                 idx = nand_ecc_precalc_table[*dat++];
  99                 reg1 ^= (idx & 0x3f);
 100
 101                 /* All bit XOR = 1 ? */
 102                 if (idx & 0x40) {
 103                         reg3 ^= (uint8_t) i;
 104                         reg2 ^= ~((uint8_t) i);
 105                 }
 106         }
 107
 108         /* Create non-inverted ECC code from line parity */
 109         tmp1  = (reg3 & 0x80) >> 0; /* B7 -> B7 */
 110         tmp1 |= (reg2 & 0x80) >> 1; /* B7 -> B6 */
 111         tmp1 |= (reg3 & 0x40) >> 1; /* B6 -> B5 */
 112         tmp1 |= (reg2 & 0x40) >> 2; /* B6 -> B4 */
 113         tmp1 |= (reg3 & 0x20) >> 2; /* B5 -> B3 */
 114         tmp1 |= (reg2 & 0x20) >> 3; /* B5 -> B2 */
 115         tmp1 |= (reg3 & 0x10) >> 3; /* B4 -> B1 */
 116         tmp1 |= (reg2 & 0x10) >> 4; /* B4 -> B0 */
 117
 118         tmp2  = (reg3 & 0x08) << 4; /* B3 -> B7 */
 119         tmp2 |= (reg2 & 0x08) << 3; /* B3 -> B6 */
 120         tmp2 |= (reg3 & 0x04) << 3; /* B2 -> B5 */
 121         tmp2 |= (reg2 & 0x04) << 2; /* B2 -> B4 */
 122         tmp2 |= (reg3 & 0x02) << 2; /* B1 -> B3 */
 123         tmp2 |= (reg2 & 0x02) << 1; /* B1 -> B2 */
 124         tmp2 |= (reg3 & 0x01) << 1; /* B0 -> B1 */
 125         tmp2 |= (reg2 & 0x01) << 0; /* B7 -> B0 */
 126
 127         /* Calculate final ECC code */
 128 #ifdef CONFIG_MTD_NAND_ECC_SMC
 129         ecc_code[0] = ~tmp2;
 130         ecc_code[1] = ~tmp1;
 131 #else
 132         ecc_code[0] = ~tmp1;
 133         ecc_code[1] = ~tmp2;
 134 #endif
 135         ecc_code[2] = ((~reg1) << 2) | 0x03;
 136
 137         return 0;
 138 }
 139 /* XXX U-BOOT XXX */
 140 #if 0
 141 EXPORT_SYMBOL(nand_calculate_ecc);
 142 #endif
 143 #endif /* CONFIG_NAND_SPL */
 144
 145 static inline int countbits(uint32_t byte)
 146 {
 147         int res = 0;
 148
 149         for (;byte; byte >>= 1)
 150                 res += byte & 0x01;
 151         return res;
 152 }
 153
 154 /**
 155  * nand_correct_data - [NAND Interface] Detect and correct bit error(s)
 156  * @mtd:        MTD block structure
 157  * @dat:        raw data read from the chip
 158  * @read_ecc:   ECC from the chip
 159  * @calc_ecc:   the ECC calculated from raw data
 160  *
 161  * Detect and correct a 1 bit error for 256 byte block
 162  */
 163 int nand_correct_data(struct mtd_info *mtd, u_char *dat,
 164                       u_char *read_ecc, u_char *calc_ecc)
 165 {
 166         uint8_t s0, s1, s2;
 167
 168 #ifdef CONFIG_MTD_NAND_ECC_SMC
 169         s0 = calc_ecc[0] ^ read_ecc[0];
 170         s1 = calc_ecc[1] ^ read_ecc[1];
 171         s2 = calc_ecc[2] ^ read_ecc[2];
 172 #else
 173         s1 = calc_ecc[0] ^ read_ecc[0];
 174         s0 = calc_ecc[1] ^ read_ecc[1];
 175         s2 = calc_ecc[2] ^ read_ecc[2];
 176 #endif
 177         if ((s0 | s1 | s2) == 0)
 178                 return 0;
 179
 180         /* Check for a single bit error */
 181         if( ((s0 ^ (s0 >> 1)) & 0x55) == 0x55 &&
 182             ((s1 ^ (s1 >> 1)) & 0x55) == 0x55 &&
 183             ((s2 ^ (s2 >> 1)) & 0x54) == 0x54) {
 184
 185                 uint32_t byteoffs, bitnum;
 186
 187                 byteoffs = (s1 << 0) & 0x80;
 188                 byteoffs |= (s1 << 1) & 0x40;
 189                 byteoffs |= (s1 << 2) & 0x20;
 190                 byteoffs |= (s1 << 3) & 0x10;
 191
 192                 byteoffs |= (s0 >> 4) & 0x08;
 193                 byteoffs |= (s0 >> 3) & 0x04;
 194                 byteoffs |= (s0 >> 2) & 0x02;
 195                 byteoffs |= (s0 >> 1) & 0x01;
 196
 197                 bitnum = (s2 >> 5) & 0x04;
 198                 bitnum |= (s2 >> 4) & 0x02;
 199                 bitnum |= (s2 >> 3) & 0x01;
 200
 201                 dat[byteoffs] ^= (1 << bitnum);
 202
 203                 return 1;
 204         }
 205
 206         if(countbits(s0 | ((uint32_t)s1 << 8) | ((uint32_t)s2 <<16)) == 1)
 207                 return 1;
 208
 209         return -1;
 210 }
 211
 212 /* XXX U-BOOT XXX */
 213 #if 0
 214 EXPORT_SYMBOL(nand_correct_data);
 215 #endif