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Wolfgang Denk932394a2005-08-17 12:55:25 +02001/*
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 * $Id: nand_ecc.c,v 1.14 2004/06/16 15:34:37 gleixner Exp $
11 *
12 * This file is free software; you can redistribute it and/or modify it
13 * under the terms of the GNU General Public License as published by the
14 * Free Software Foundation; either version 2 or (at your option) any
15 * later version.
Wolfgang Denkac7eb8a32005-09-14 23:53:32 +020016 *
Wolfgang Denk932394a2005-08-17 12:55:25 +020017 * This file is distributed in the hope that it will be useful, but WITHOUT
18 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
19 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
20 * for more details.
Wolfgang Denkac7eb8a32005-09-14 23:53:32 +020021 *
Wolfgang Denk932394a2005-08-17 12:55:25 +020022 * You should have received a copy of the GNU General Public License along
23 * with this file; if not, write to the Free Software Foundation, Inc.,
24 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
Wolfgang Denkac7eb8a32005-09-14 23:53:32 +020025 *
Wolfgang Denk932394a2005-08-17 12:55:25 +020026 * As a special exception, if other files instantiate templates or use
27 * macros or inline functions from these files, or you compile these
28 * files and link them with other works to produce a work based on these
29 * files, these files do not by themselves cause the resulting work to be
30 * covered by the GNU General Public License. However the source code for
31 * these files must still be made available in accordance with section (3)
32 * of the GNU General Public License.
Wolfgang Denkac7eb8a32005-09-14 23:53:32 +020033 *
Wolfgang Denk932394a2005-08-17 12:55:25 +020034 * This exception does not invalidate any other reasons why a work based on
35 * this file might be covered by the GNU General Public License.
36 */
37
38#include <common.h>
39
Marian Balakowicz6db39702006-04-08 19:08:06 +020040#if (CONFIG_COMMANDS & CFG_CMD_NAND) && !defined(CFG_NAND_LEGACY)
Wolfgang Denk932394a2005-08-17 12:55:25 +020041
Bartlomiej Sieka038ccac2006-02-24 09:37:22 +010042#include<linux/mtd/mtd.h>
Wolfgang Denk932394a2005-08-17 12:55:25 +020043/*
44 * Pre-calculated 256-way 1 byte column parity
45 */
46static const u_char nand_ecc_precalc_table[] = {
47 0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a, 0x5a, 0x0f, 0x0c, 0x59, 0x03, 0x56, 0x55, 0x00,
48 0x65, 0x30, 0x33, 0x66, 0x3c, 0x69, 0x6a, 0x3f, 0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65,
49 0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c, 0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66,
50 0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59, 0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03,
51 0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65, 0x66, 0x33, 0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69,
52 0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56, 0x56, 0x03, 0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c,
53 0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03, 0x00, 0x55, 0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f,
54 0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30, 0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a,
55 0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30, 0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a,
56 0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03, 0x00, 0x55, 0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f,
57 0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56, 0x56, 0x03, 0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c,
58 0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65, 0x66, 0x33, 0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69,
59 0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59, 0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03,
60 0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c, 0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66,
61 0x65, 0x30, 0x33, 0x66, 0x3c, 0x69, 0x6a, 0x3f, 0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65,
62 0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a, 0x5a, 0x0f, 0x0c, 0x59, 0x03, 0x56, 0x55, 0x00
63};
64
65
66/**
67 * nand_trans_result - [GENERIC] create non-inverted ECC
68 * @reg2: line parity reg 2
69 * @reg3: line parity reg 3
Wolfgang Denkac7eb8a32005-09-14 23:53:32 +020070 * @ecc_code: ecc
Wolfgang Denk932394a2005-08-17 12:55:25 +020071 *
72 * Creates non-inverted ECC code from line parity
73 */
74static void nand_trans_result(u_char reg2, u_char reg3,
75 u_char *ecc_code)
76{
77 u_char a, b, i, tmp1, tmp2;
Wolfgang Denkac7eb8a32005-09-14 23:53:32 +020078
Wolfgang Denk932394a2005-08-17 12:55:25 +020079 /* Initialize variables */
80 a = b = 0x80;
81 tmp1 = tmp2 = 0;
Wolfgang Denkac7eb8a32005-09-14 23:53:32 +020082
Wolfgang Denk932394a2005-08-17 12:55:25 +020083 /* Calculate first ECC byte */
84 for (i = 0; i < 4; i++) {
85 if (reg3 & a) /* LP15,13,11,9 --> ecc_code[0] */
86 tmp1 |= b;
87 b >>= 1;
88 if (reg2 & a) /* LP14,12,10,8 --> ecc_code[0] */
89 tmp1 |= b;
90 b >>= 1;
91 a >>= 1;
92 }
Wolfgang Denkac7eb8a32005-09-14 23:53:32 +020093
Wolfgang Denk932394a2005-08-17 12:55:25 +020094 /* Calculate second ECC byte */
95 b = 0x80;
96 for (i = 0; i < 4; i++) {
97 if (reg3 & a) /* LP7,5,3,1 --> ecc_code[1] */
98 tmp2 |= b;
99 b >>= 1;
100 if (reg2 & a) /* LP6,4,2,0 --> ecc_code[1] */
101 tmp2 |= b;
102 b >>= 1;
103 a >>= 1;
104 }
Wolfgang Denkac7eb8a32005-09-14 23:53:32 +0200105
Wolfgang Denk932394a2005-08-17 12:55:25 +0200106 /* Store two of the ECC bytes */
107 ecc_code[0] = tmp1;
108 ecc_code[1] = tmp2;
109}
110
111/**
112 * nand_calculate_ecc - [NAND Interface] Calculate 3 byte ECC code for 256 byte block
113 * @mtd: MTD block structure
114 * @dat: raw data
115 * @ecc_code: buffer for ECC
116 */
117int nand_calculate_ecc(struct mtd_info *mtd, const u_char *dat, u_char *ecc_code)
118{
119 u_char idx, reg1, reg2, reg3;
120 int j;
Wolfgang Denkac7eb8a32005-09-14 23:53:32 +0200121
Wolfgang Denk932394a2005-08-17 12:55:25 +0200122 /* Initialize variables */
123 reg1 = reg2 = reg3 = 0;
124 ecc_code[0] = ecc_code[1] = ecc_code[2] = 0;
Wolfgang Denkac7eb8a32005-09-14 23:53:32 +0200125
126 /* Build up column parity */
Wolfgang Denk932394a2005-08-17 12:55:25 +0200127 for(j = 0; j < 256; j++) {
Wolfgang Denkac7eb8a32005-09-14 23:53:32 +0200128
Wolfgang Denk932394a2005-08-17 12:55:25 +0200129 /* Get CP0 - CP5 from table */
130 idx = nand_ecc_precalc_table[dat[j]];
131 reg1 ^= (idx & 0x3f);
Wolfgang Denkac7eb8a32005-09-14 23:53:32 +0200132
Wolfgang Denk932394a2005-08-17 12:55:25 +0200133 /* All bit XOR = 1 ? */
134 if (idx & 0x40) {
135 reg3 ^= (u_char) j;
136 reg2 ^= ~((u_char) j);
137 }
138 }
Wolfgang Denkac7eb8a32005-09-14 23:53:32 +0200139
Wolfgang Denk932394a2005-08-17 12:55:25 +0200140 /* Create non-inverted ECC code from line parity */
141 nand_trans_result(reg2, reg3, ecc_code);
Wolfgang Denkac7eb8a32005-09-14 23:53:32 +0200142
Wolfgang Denk932394a2005-08-17 12:55:25 +0200143 /* Calculate final ECC code */
144 ecc_code[0] = ~ecc_code[0];
145 ecc_code[1] = ~ecc_code[1];
146 ecc_code[2] = ((~reg1) << 2) | 0x03;
147 return 0;
148}
149
150/**
151 * nand_correct_data - [NAND Interface] Detect and correct bit error(s)
152 * @mtd: MTD block structure
153 * @dat: raw data read from the chip
154 * @read_ecc: ECC from the chip
155 * @calc_ecc: the ECC calculated from raw data
156 *
157 * Detect and correct a 1 bit error for 256 byte block
158 */
159int nand_correct_data(struct mtd_info *mtd, u_char *dat, u_char *read_ecc, u_char *calc_ecc)
160{
161 u_char a, b, c, d1, d2, d3, add, bit, i;
Wolfgang Denkac7eb8a32005-09-14 23:53:32 +0200162
163 /* Do error detection */
Wolfgang Denk932394a2005-08-17 12:55:25 +0200164 d1 = calc_ecc[0] ^ read_ecc[0];
165 d2 = calc_ecc[1] ^ read_ecc[1];
166 d3 = calc_ecc[2] ^ read_ecc[2];
Wolfgang Denkac7eb8a32005-09-14 23:53:32 +0200167
Wolfgang Denk932394a2005-08-17 12:55:25 +0200168 if ((d1 | d2 | d3) == 0) {
169 /* No errors */
170 return 0;
171 }
172 else {
173 a = (d1 ^ (d1 >> 1)) & 0x55;
174 b = (d2 ^ (d2 >> 1)) & 0x55;
175 c = (d3 ^ (d3 >> 1)) & 0x54;
Wolfgang Denkac7eb8a32005-09-14 23:53:32 +0200176
Wolfgang Denk932394a2005-08-17 12:55:25 +0200177 /* Found and will correct single bit error in the data */
178 if ((a == 0x55) && (b == 0x55) && (c == 0x54)) {
179 c = 0x80;
180 add = 0;
181 a = 0x80;
182 for (i=0; i<4; i++) {
183 if (d1 & c)
184 add |= a;
185 c >>= 2;
186 a >>= 1;
187 }
188 c = 0x80;
189 for (i=0; i<4; i++) {
190 if (d2 & c)
191 add |= a;
192 c >>= 2;
193 a >>= 1;
194 }
195 bit = 0;
196 b = 0x04;
197 c = 0x80;
198 for (i=0; i<3; i++) {
199 if (d3 & c)
200 bit |= b;
201 c >>= 2;
202 b >>= 1;
203 }
204 b = 0x01;
205 a = dat[add];
206 a ^= (b << bit);
207 dat[add] = a;
208 return 1;
Wolfgang Denkac7eb8a32005-09-14 23:53:32 +0200209 } else {
Wolfgang Denk932394a2005-08-17 12:55:25 +0200210 i = 0;
211 while (d1) {
212 if (d1 & 0x01)
213 ++i;
214 d1 >>= 1;
215 }
216 while (d2) {
217 if (d2 & 0x01)
218 ++i;
219 d2 >>= 1;
220 }
221 while (d3) {
222 if (d3 & 0x01)
223 ++i;
224 d3 >>= 1;
225 }
226 if (i == 1) {
227 /* ECC Code Error Correction */
228 read_ecc[0] = calc_ecc[0];
229 read_ecc[1] = calc_ecc[1];
230 read_ecc[2] = calc_ecc[2];
231 return 2;
232 }
233 else {
234 /* Uncorrectable Error */
235 return -1;
236 }
237 }
238 }
Wolfgang Denkac7eb8a32005-09-14 23:53:32 +0200239
Wolfgang Denk932394a2005-08-17 12:55:25 +0200240 /* Should never happen */
241 return -1;
242}
243
244#endif /* CONFIG_COMMANDS & CFG_CMD_NAND */