1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * This file contains an ECC algorithm from Toshiba that detects and 4 * corrects 1 bit errors in a 256 byte block of data. 5 * 6 * drivers/mtd/nand/raw/nand_ecc.c 7 * 8 * Copyright (C) 2000-2004 Steven J. Hill (sjhill@realitydiluted.com) 9 * Toshiba America Electronics Components, Inc. 10 * 11 * Copyright (C) 2006 Thomas Gleixner <tglx@linutronix.de> 12 * 13 * As a special exception, if other files instantiate templates or use 14 * macros or inline functions from these files, or you compile these 15 * files and link them with other works to produce a work based on these 16 * files, these files do not by themselves cause the resulting work to be 17 * covered by the GNU General Public License. However the source code for 18 * these files must still be made available in accordance with section (3) 19 * of the GNU General Public License. 20 * 21 * This exception does not invalidate any other reasons why a work based on 22 * this file might be covered by the GNU General Public License. 23 */ 24 25 #include <common.h> 26 27 #include <linux/errno.h> 28 #include <linux/mtd/mtd.h> 29 #include <linux/mtd/nand_ecc.h> 30 31 /* 32 * NAND-SPL has no sofware ECC for now, so don't include nand_calculate_ecc(), 33 * only nand_correct_data() is needed 34 */ 35 36 #if !defined(CONFIG_NAND_SPL) || defined(CONFIG_SPL_NAND_SOFTECC) 37 /* 38 * Pre-calculated 256-way 1 byte column parity 39 */ 40 static const u_char nand_ecc_precalc_table[] = { 41 0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a, 0x5a, 0x0f, 0x0c, 0x59, 0x03, 0x56, 0x55, 0x00, 42 0x65, 0x30, 0x33, 0x66, 0x3c, 0x69, 0x6a, 0x3f, 0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65, 43 0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c, 0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66, 44 0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59, 0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03, 45 0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65, 0x66, 0x33, 0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69, 46 0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56, 0x56, 0x03, 0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c, 47 0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03, 0x00, 0x55, 0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f, 48 0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30, 0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a, 49 0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30, 0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a, 50 0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03, 0x00, 0x55, 0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f, 51 0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56, 0x56, 0x03, 0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c, 52 0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65, 0x66, 0x33, 0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69, 53 0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59, 0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03, 54 0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c, 0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66, 55 0x65, 0x30, 0x33, 0x66, 0x3c, 0x69, 0x6a, 0x3f, 0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65, 56 0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a, 0x5a, 0x0f, 0x0c, 0x59, 0x03, 0x56, 0x55, 0x00 57 }; 58 59 /** 60 * nand_calculate_ecc - [NAND Interface] Calculate 3-byte ECC for 256-byte block 61 * @mtd: MTD block structure 62 * @dat: raw data 63 * @ecc_code: buffer for ECC 64 */ 65 int nand_calculate_ecc(struct mtd_info *mtd, const u_char *dat, 66 u_char *ecc_code) 67 { 68 uint8_t idx, reg1, reg2, reg3, tmp1, tmp2; 69 int i; 70 71 /* Initialize variables */ 72 reg1 = reg2 = reg3 = 0; 73 74 /* Build up column parity */ 75 for(i = 0; i < 256; i++) { 76 /* Get CP0 - CP5 from table */ 77 idx = nand_ecc_precalc_table[*dat++]; 78 reg1 ^= (idx & 0x3f); 79 80 /* All bit XOR = 1 ? */ 81 if (idx & 0x40) { 82 reg3 ^= (uint8_t) i; 83 reg2 ^= ~((uint8_t) i); 84 } 85 } 86 87 /* Create non-inverted ECC code from line parity */ 88 tmp1 = (reg3 & 0x80) >> 0; /* B7 -> B7 */ 89 tmp1 |= (reg2 & 0x80) >> 1; /* B7 -> B6 */ 90 tmp1 |= (reg3 & 0x40) >> 1; /* B6 -> B5 */ 91 tmp1 |= (reg2 & 0x40) >> 2; /* B6 -> B4 */ 92 tmp1 |= (reg3 & 0x20) >> 2; /* B5 -> B3 */ 93 tmp1 |= (reg2 & 0x20) >> 3; /* B5 -> B2 */ 94 tmp1 |= (reg3 & 0x10) >> 3; /* B4 -> B1 */ 95 tmp1 |= (reg2 & 0x10) >> 4; /* B4 -> B0 */ 96 97 tmp2 = (reg3 & 0x08) << 4; /* B3 -> B7 */ 98 tmp2 |= (reg2 & 0x08) << 3; /* B3 -> B6 */ 99 tmp2 |= (reg3 & 0x04) << 3; /* B2 -> B5 */ 100 tmp2 |= (reg2 & 0x04) << 2; /* B2 -> B4 */ 101 tmp2 |= (reg3 & 0x02) << 2; /* B1 -> B3 */ 102 tmp2 |= (reg2 & 0x02) << 1; /* B1 -> B2 */ 103 tmp2 |= (reg3 & 0x01) << 1; /* B0 -> B1 */ 104 tmp2 |= (reg2 & 0x01) << 0; /* B7 -> B0 */ 105 106 /* Calculate final ECC code */ 107 ecc_code[0] = ~tmp1; 108 ecc_code[1] = ~tmp2; 109 ecc_code[2] = ((~reg1) << 2) | 0x03; 110 111 return 0; 112 } 113 #endif /* CONFIG_NAND_SPL */ 114 115 static inline int countbits(uint32_t byte) 116 { 117 int res = 0; 118 119 for (;byte; byte >>= 1) 120 res += byte & 0x01; 121 return res; 122 } 123 124 /** 125 * nand_correct_data - [NAND Interface] Detect and correct bit error(s) 126 * @mtd: MTD block structure 127 * @dat: raw data read from the chip 128 * @read_ecc: ECC from the chip 129 * @calc_ecc: the ECC calculated from raw data 130 * 131 * Detect and correct a 1 bit error for 256 byte block 132 */ 133 int nand_correct_data(struct mtd_info *mtd, u_char *dat, 134 u_char *read_ecc, u_char *calc_ecc) 135 { 136 uint8_t s0, s1, s2; 137 138 s1 = calc_ecc[0] ^ read_ecc[0]; 139 s0 = calc_ecc[1] ^ read_ecc[1]; 140 s2 = calc_ecc[2] ^ read_ecc[2]; 141 if ((s0 | s1 | s2) == 0) 142 return 0; 143 144 /* Check for a single bit error */ 145 if( ((s0 ^ (s0 >> 1)) & 0x55) == 0x55 && 146 ((s1 ^ (s1 >> 1)) & 0x55) == 0x55 && 147 ((s2 ^ (s2 >> 1)) & 0x54) == 0x54) { 148 149 uint32_t byteoffs, bitnum; 150 151 byteoffs = (s1 << 0) & 0x80; 152 byteoffs |= (s1 << 1) & 0x40; 153 byteoffs |= (s1 << 2) & 0x20; 154 byteoffs |= (s1 << 3) & 0x10; 155 156 byteoffs |= (s0 >> 4) & 0x08; 157 byteoffs |= (s0 >> 3) & 0x04; 158 byteoffs |= (s0 >> 2) & 0x02; 159 byteoffs |= (s0 >> 1) & 0x01; 160 161 bitnum = (s2 >> 5) & 0x04; 162 bitnum |= (s2 >> 4) & 0x02; 163 bitnum |= (s2 >> 3) & 0x01; 164 165 dat[byteoffs] ^= (1 << bitnum); 166 167 return 1; 168 } 169 170 if(countbits(s0 | ((uint32_t)s1 << 8) | ((uint32_t)s2 <<16)) == 1) 171 return 1; 172 173 return -EBADMSG; 174 } 175