blob: fde593e5e634b7ecf564d2f3f04ba5d6c5294636 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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 *
Thomas Gleixner819d6a32006-05-23 11:32:45 +020010 * Copyright (C) 2006 Thomas Gleixner <tglx@linutronix.de>
11 *
Thomas Gleixner61b03bd2005-11-07 11:15:49 +000012 * $Id: nand_ecc.c,v 1.15 2005/11/07 11:14:30 gleixner Exp $
Linus Torvalds1da177e2005-04-16 15:20:36 -070013 *
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.
Thomas Gleixner61b03bd2005-11-07 11:15:49 +000018 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070019 * 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.
Thomas Gleixner61b03bd2005-11-07 11:15:49 +000023 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070024 * 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.
Thomas Gleixner61b03bd2005-11-07 11:15:49 +000027 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070028 * 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.
Thomas Gleixner61b03bd2005-11-07 11:15:49 +000035 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070036 * 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 <linux/types.h>
41#include <linux/kernel.h>
42#include <linux/module.h>
43#include <linux/mtd/nand_ecc.h>
44
45/*
46 * Pre-calculated 256-way 1 byte column parity
47 */
48static const u_char nand_ecc_precalc_table[] = {
49 0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a, 0x5a, 0x0f, 0x0c, 0x59, 0x03, 0x56, 0x55, 0x00,
50 0x65, 0x30, 0x33, 0x66, 0x3c, 0x69, 0x6a, 0x3f, 0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65,
51 0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c, 0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66,
52 0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59, 0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03,
53 0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65, 0x66, 0x33, 0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69,
54 0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56, 0x56, 0x03, 0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c,
55 0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03, 0x00, 0x55, 0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f,
56 0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30, 0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a,
57 0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30, 0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a,
58 0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03, 0x00, 0x55, 0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f,
59 0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56, 0x56, 0x03, 0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c,
60 0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65, 0x66, 0x33, 0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69,
61 0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59, 0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03,
62 0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c, 0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66,
63 0x65, 0x30, 0x33, 0x66, 0x3c, 0x69, 0x6a, 0x3f, 0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65,
64 0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a, 0x5a, 0x0f, 0x0c, 0x59, 0x03, 0x56, 0x55, 0x00
65};
66
Linus Torvalds1da177e2005-04-16 15:20:36 -070067/**
Randy Dunlap844d3b42006-06-28 21:48:27 -070068 * nand_calculate_ecc - [NAND Interface] Calculate 3-byte ECC for 256-byte block
Linus Torvalds1da177e2005-04-16 15:20:36 -070069 * @mtd: MTD block structure
70 * @dat: raw data
71 * @ecc_code: buffer for ECC
72 */
Thomas Gleixner819d6a32006-05-23 11:32:45 +020073int nand_calculate_ecc(struct mtd_info *mtd, const u_char *dat,
74 u_char *ecc_code)
Linus Torvalds1da177e2005-04-16 15:20:36 -070075{
Thomas Gleixner819d6a32006-05-23 11:32:45 +020076 uint8_t idx, reg1, reg2, reg3, tmp1, tmp2;
77 int i;
Thomas Gleixner61b03bd2005-11-07 11:15:49 +000078
Linus Torvalds1da177e2005-04-16 15:20:36 -070079 /* Initialize variables */
80 reg1 = reg2 = reg3 = 0;
Thomas Gleixner61b03bd2005-11-07 11:15:49 +000081
82 /* Build up column parity */
Thomas Gleixner819d6a32006-05-23 11:32:45 +020083 for(i = 0; i < 256; i++) {
Linus Torvalds1da177e2005-04-16 15:20:36 -070084 /* Get CP0 - CP5 from table */
Thomas Gleixner819d6a32006-05-23 11:32:45 +020085 idx = nand_ecc_precalc_table[*dat++];
Linus Torvalds1da177e2005-04-16 15:20:36 -070086 reg1 ^= (idx & 0x3f);
Thomas Gleixner61b03bd2005-11-07 11:15:49 +000087
Linus Torvalds1da177e2005-04-16 15:20:36 -070088 /* All bit XOR = 1 ? */
89 if (idx & 0x40) {
Thomas Gleixner819d6a32006-05-23 11:32:45 +020090 reg3 ^= (uint8_t) i;
91 reg2 ^= ~((uint8_t) i);
Linus Torvalds1da177e2005-04-16 15:20:36 -070092 }
93 }
Thomas Gleixner61b03bd2005-11-07 11:15:49 +000094
Linus Torvalds1da177e2005-04-16 15:20:36 -070095 /* Create non-inverted ECC code from line parity */
Thomas Gleixner819d6a32006-05-23 11:32:45 +020096 tmp1 = (reg3 & 0x80) >> 0; /* B7 -> B7 */
97 tmp1 |= (reg2 & 0x80) >> 1; /* B7 -> B6 */
98 tmp1 |= (reg3 & 0x40) >> 1; /* B6 -> B5 */
99 tmp1 |= (reg2 & 0x40) >> 2; /* B6 -> B4 */
100 tmp1 |= (reg3 & 0x20) >> 2; /* B5 -> B3 */
101 tmp1 |= (reg2 & 0x20) >> 3; /* B5 -> B2 */
102 tmp1 |= (reg3 & 0x10) >> 3; /* B4 -> B1 */
103 tmp1 |= (reg2 & 0x10) >> 4; /* B4 -> B0 */
104
105 tmp2 = (reg3 & 0x08) << 4; /* B3 -> B7 */
106 tmp2 |= (reg2 & 0x08) << 3; /* B3 -> B6 */
107 tmp2 |= (reg3 & 0x04) << 3; /* B2 -> B5 */
108 tmp2 |= (reg2 & 0x04) << 2; /* B2 -> B4 */
109 tmp2 |= (reg3 & 0x02) << 2; /* B1 -> B3 */
110 tmp2 |= (reg2 & 0x02) << 1; /* B1 -> B2 */
111 tmp2 |= (reg3 & 0x01) << 1; /* B0 -> B1 */
112 tmp2 |= (reg2 & 0x01) << 0; /* B7 -> B0 */
Thomas Gleixner61b03bd2005-11-07 11:15:49 +0000113
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114 /* Calculate final ECC code */
Timo Lindhorstfc029192006-11-27 13:35:49 +0100115#ifdef CONFIG_MTD_NAND_ECC_SMC
Thomas Gleixner819d6a32006-05-23 11:32:45 +0200116 ecc_code[0] = ~tmp2;
117 ecc_code[1] = ~tmp1;
118#else
119 ecc_code[0] = ~tmp1;
120 ecc_code[1] = ~tmp2;
121#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122 ecc_code[2] = ((~reg1) << 2) | 0x03;
Thomas Gleixner819d6a32006-05-23 11:32:45 +0200123
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124 return 0;
125}
Thomas Gleixner819d6a32006-05-23 11:32:45 +0200126EXPORT_SYMBOL(nand_calculate_ecc);
127
128static inline int countbits(uint32_t byte)
129{
130 int res = 0;
131
132 for (;byte; byte >>= 1)
133 res += byte & 0x01;
134 return res;
135}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136
137/**
138 * nand_correct_data - [NAND Interface] Detect and correct bit error(s)
139 * @mtd: MTD block structure
140 * @dat: raw data read from the chip
141 * @read_ecc: ECC from the chip
142 * @calc_ecc: the ECC calculated from raw data
143 *
144 * Detect and correct a 1 bit error for 256 byte block
145 */
Thomas Gleixner819d6a32006-05-23 11:32:45 +0200146int nand_correct_data(struct mtd_info *mtd, u_char *dat,
147 u_char *read_ecc, u_char *calc_ecc)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700148{
Thomas Gleixner819d6a32006-05-23 11:32:45 +0200149 uint8_t s0, s1, s2;
Thomas Gleixner61b03bd2005-11-07 11:15:49 +0000150
Timo Lindhorstfc029192006-11-27 13:35:49 +0100151#ifdef CONFIG_MTD_NAND_ECC_SMC
Thomas Gleixner819d6a32006-05-23 11:32:45 +0200152 s0 = calc_ecc[0] ^ read_ecc[0];
153 s1 = calc_ecc[1] ^ read_ecc[1];
154 s2 = calc_ecc[2] ^ read_ecc[2];
155#else
156 s1 = calc_ecc[0] ^ read_ecc[0];
157 s0 = calc_ecc[1] ^ read_ecc[1];
158 s2 = calc_ecc[2] ^ read_ecc[2];
159#endif
160 if ((s0 | s1 | s2) == 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161 return 0;
Thomas Gleixner61b03bd2005-11-07 11:15:49 +0000162
Thomas Gleixner819d6a32006-05-23 11:32:45 +0200163 /* Check for a single bit error */
164 if( ((s0 ^ (s0 >> 1)) & 0x55) == 0x55 &&
165 ((s1 ^ (s1 >> 1)) & 0x55) == 0x55 &&
166 ((s2 ^ (s2 >> 1)) & 0x54) == 0x54) {
167
168 uint32_t byteoffs, bitnum;
169
170 byteoffs = (s1 << 0) & 0x80;
171 byteoffs |= (s1 << 1) & 0x40;
172 byteoffs |= (s1 << 2) & 0x20;
173 byteoffs |= (s1 << 3) & 0x10;
174
175 byteoffs |= (s0 >> 4) & 0x08;
176 byteoffs |= (s0 >> 3) & 0x04;
177 byteoffs |= (s0 >> 2) & 0x02;
178 byteoffs |= (s0 >> 1) & 0x01;
179
180 bitnum = (s2 >> 5) & 0x04;
181 bitnum |= (s2 >> 4) & 0x02;
182 bitnum |= (s2 >> 3) & 0x01;
183
184 dat[byteoffs] ^= (1 << bitnum);
185
186 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187 }
Thomas Gleixner61b03bd2005-11-07 11:15:49 +0000188
Thomas Gleixner819d6a32006-05-23 11:32:45 +0200189 if(countbits(s0 | ((uint32_t)s1 << 8) | ((uint32_t)s2 <<16)) == 1)
190 return 1;
191
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192 return -1;
193}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194EXPORT_SYMBOL(nand_correct_data);
195
196MODULE_LICENSE("GPL");
197MODULE_AUTHOR("Steven J. Hill <sjhill@realitydiluted.com>");
198MODULE_DESCRIPTION("Generic NAND ECC support");