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/raw/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 * SPDX-License-Identifier: GPL-2.0+ 13 * 14 * As a special exception, if other files instantiate templates or use 15 * macros or inline functions from these files, or you compile these 16 * files and link them with other works to produce a work based on these 17 * files, these files do not by themselves cause the resulting work to be 18 * covered by the GNU General Public License. However the source code for 19 * these files must still be made available in accordance with section (3) 20 * of the GNU General Public License. 21 * 22 * This exception does not invalidate any other reasons why a work based on 23 * this file might be covered by the GNU General Public License. 24 */ 25 26 #include <common.h> 27 28 #include <linux/errno.h> 29 #include <linux/mtd/mtd.h> 30 #include <linux/mtd/nand_ecc.h> 31 32 /* 33 * NAND-SPL has no sofware ECC for now, so don't include nand_calculate_ecc(), 34 * only nand_correct_data() is needed 35 */ 36 37 #if !defined(CONFIG_NAND_SPL) || defined(CONFIG_SPL_NAND_SOFTECC) 38 /* 39 * Pre-calculated 256-way 1 byte column parity 40 */ 41 static const u_char nand_ecc_precalc_table[] = { 42 0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a, 0x5a, 0x0f, 0x0c, 0x59, 0x03, 0x56, 0x55, 0x00, 43 0x65, 0x30, 0x33, 0x66, 0x3c, 0x69, 0x6a, 0x3f, 0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65, 44 0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c, 0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66, 45 0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59, 0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03, 46 0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65, 0x66, 0x33, 0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69, 47 0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56, 0x56, 0x03, 0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c, 48 0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03, 0x00, 0x55, 0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f, 49 0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30, 0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a, 50 0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30, 0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a, 51 0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03, 0x00, 0x55, 0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f, 52 0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56, 0x56, 0x03, 0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c, 53 0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65, 0x66, 0x33, 0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69, 54 0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59, 0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03, 55 0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c, 0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66, 56 0x65, 0x30, 0x33, 0x66, 0x3c, 0x69, 0x6a, 0x3f, 0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65, 57 0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a, 0x5a, 0x0f, 0x0c, 0x59, 0x03, 0x56, 0x55, 0x00 58 }; 59 60 /** 61 * nand_calculate_ecc - [NAND Interface] Calculate 3-byte ECC for 256-byte block 62 * @mtd: MTD block structure 63 * @dat: raw data 64 * @ecc_code: buffer for ECC 65 */ 66 int nand_calculate_ecc(struct mtd_info *mtd, const u_char *dat, 67 u_char *ecc_code) 68 { 69 uint8_t idx, reg1, reg2, reg3, tmp1, tmp2; 70 int i; 71 72 /* Initialize variables */ 73 reg1 = reg2 = reg3 = 0; 74 75 /* Build up column parity */ 76 for(i = 0; i < 256; i++) { 77 /* Get CP0 - CP5 from table */ 78 idx = nand_ecc_precalc_table[*dat++]; 79 reg1 ^= (idx & 0x3f); 80 81 /* All bit XOR = 1 ? */ 82 if (idx & 0x40) { 83 reg3 ^= (uint8_t) i; 84 reg2 ^= ~((uint8_t) i); 85 } 86 } 87 88 /* Create non-inverted ECC code from line parity */ 89 tmp1 = (reg3 & 0x80) >> 0; /* B7 -> B7 */ 90 tmp1 |= (reg2 & 0x80) >> 1; /* B7 -> B6 */ 91 tmp1 |= (reg3 & 0x40) >> 1; /* B6 -> B5 */ 92 tmp1 |= (reg2 & 0x40) >> 2; /* B6 -> B4 */ 93 tmp1 |= (reg3 & 0x20) >> 2; /* B5 -> B3 */ 94 tmp1 |= (reg2 & 0x20) >> 3; /* B5 -> B2 */ 95 tmp1 |= (reg3 & 0x10) >> 3; /* B4 -> B1 */ 96 tmp1 |= (reg2 & 0x10) >> 4; /* B4 -> B0 */ 97 98 tmp2 = (reg3 & 0x08) << 4; /* B3 -> B7 */ 99 tmp2 |= (reg2 & 0x08) << 3; /* B3 -> B6 */ 100 tmp2 |= (reg3 & 0x04) << 3; /* B2 -> B5 */ 101 tmp2 |= (reg2 & 0x04) << 2; /* B2 -> B4 */ 102 tmp2 |= (reg3 & 0x02) << 2; /* B1 -> B3 */ 103 tmp2 |= (reg2 & 0x02) << 1; /* B1 -> B2 */ 104 tmp2 |= (reg3 & 0x01) << 1; /* B0 -> B1 */ 105 tmp2 |= (reg2 & 0x01) << 0; /* B7 -> B0 */ 106 107 /* Calculate final ECC code */ 108 ecc_code[0] = ~tmp1; 109 ecc_code[1] = ~tmp2; 110 ecc_code[2] = ((~reg1) << 2) | 0x03; 111 112 return 0; 113 } 114 #endif /* CONFIG_NAND_SPL */ 115 116 static inline int countbits(uint32_t byte) 117 { 118 int res = 0; 119 120 for (;byte; byte >>= 1) 121 res += byte & 0x01; 122 return res; 123 } 124 125 /** 126 * nand_correct_data - [NAND Interface] Detect and correct bit error(s) 127 * @mtd: MTD block structure 128 * @dat: raw data read from the chip 129 * @read_ecc: ECC from the chip 130 * @calc_ecc: the ECC calculated from raw data 131 * 132 * Detect and correct a 1 bit error for 256 byte block 133 */ 134 int nand_correct_data(struct mtd_info *mtd, u_char *dat, 135 u_char *read_ecc, u_char *calc_ecc) 136 { 137 uint8_t s0, s1, s2; 138 139 s1 = calc_ecc[0] ^ read_ecc[0]; 140 s0 = calc_ecc[1] ^ read_ecc[1]; 141 s2 = calc_ecc[2] ^ read_ecc[2]; 142 if ((s0 | s1 | s2) == 0) 143 return 0; 144 145 /* Check for a single bit error */ 146 if( ((s0 ^ (s0 >> 1)) & 0x55) == 0x55 && 147 ((s1 ^ (s1 >> 1)) & 0x55) == 0x55 && 148 ((s2 ^ (s2 >> 1)) & 0x54) == 0x54) { 149 150 uint32_t byteoffs, bitnum; 151 152 byteoffs = (s1 << 0) & 0x80; 153 byteoffs |= (s1 << 1) & 0x40; 154 byteoffs |= (s1 << 2) & 0x20; 155 byteoffs |= (s1 << 3) & 0x10; 156 157 byteoffs |= (s0 >> 4) & 0x08; 158 byteoffs |= (s0 >> 3) & 0x04; 159 byteoffs |= (s0 >> 2) & 0x02; 160 byteoffs |= (s0 >> 1) & 0x01; 161 162 bitnum = (s2 >> 5) & 0x04; 163 bitnum |= (s2 >> 4) & 0x02; 164 bitnum |= (s2 >> 3) & 0x01; 165 166 dat[byteoffs] ^= (1 << bitnum); 167 168 return 1; 169 } 170 171 if(countbits(s0 | ((uint32_t)s1 << 8) | ((uint32_t)s2 <<16)) == 1) 172 return 1; 173 174 return -EBADMSG; 175 } 176