diff options
Diffstat (limited to 'drivers/mtd/nand/nand_ecc.c')
| -rw-r--r-- | drivers/mtd/nand/nand_ecc.c | 198 |
1 files changed, 198 insertions, 0 deletions
diff --git a/drivers/mtd/nand/nand_ecc.c b/drivers/mtd/nand/nand_ecc.c new file mode 100644 index 0000000000..266d57318b --- /dev/null +++ b/drivers/mtd/nand/nand_ecc.c @@ -0,0 +1,198 @@ +/* + * This file contains an ECC algorithm from Toshiba that detects and + * corrects 1 bit errors in a 256 byte block of data. + * + * drivers/mtd/nand/nand_ecc.c + * + * Copyright (C) 2000-2004 Steven J. Hill (sjhill@realitydiluted.com) + * Toshiba America Electronics Components, Inc. + * + * Copyright (C) 2006 Thomas Gleixner <tglx@linutronix.de> + * + * $Id: nand_ecc.c,v 1.15 2005/11/07 11:14:30 gleixner Exp $ + * + * This file is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2 or (at your option) any + * later version. + * + * This file is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * for more details. + * + * You should have received a copy of the GNU General Public License along + * with this file; if not, write to the Free Software Foundation, Inc., + * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. + * + * As a special exception, if other files instantiate templates or use + * macros or inline functions from these files, or you compile these + * files and link them with other works to produce a work based on these + * files, these files do not by themselves cause the resulting work to be + * covered by the GNU General Public License. However the source code for + * these files must still be made available in accordance with section (3) + * of the GNU General Public License. + * + * This exception does not invalidate any other reasons why a work based on + * this file might be covered by the GNU General Public License. + */ + +#include <linux/types.h> +#include <common.h> +#include <errno.h> +#include <linux/mtd/nand_ecc.h> + +/* + * Pre-calculated 256-way 1 byte column parity + */ +static const u_char nand_ecc_precalc_table[] = { + 0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a, 0x5a, 0x0f, 0x0c, 0x59, 0x03, 0x56, 0x55, 0x00, + 0x65, 0x30, 0x33, 0x66, 0x3c, 0x69, 0x6a, 0x3f, 0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65, + 0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c, 0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66, + 0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59, 0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03, + 0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65, 0x66, 0x33, 0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69, + 0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56, 0x56, 0x03, 0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c, + 0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03, 0x00, 0x55, 0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f, + 0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30, 0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a, + 0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30, 0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a, + 0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03, 0x00, 0x55, 0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f, + 0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56, 0x56, 0x03, 0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c, + 0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65, 0x66, 0x33, 0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69, + 0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59, 0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03, + 0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c, 0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66, + 0x65, 0x30, 0x33, 0x66, 0x3c, 0x69, 0x6a, 0x3f, 0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65, + 0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a, 0x5a, 0x0f, 0x0c, 0x59, 0x03, 0x56, 0x55, 0x00 +}; + +/** + * nand_calculate_ecc - [NAND Interface] Calculate 3-byte ECC for 256-byte block + * @mtd: MTD block structure + * @dat: raw data + * @ecc_code: buffer for ECC + */ +int nand_calculate_ecc(struct mtd_info *mtd, const u_char *dat, + u_char *ecc_code) +{ + uint8_t idx, reg1, reg2, reg3, tmp1, tmp2; + int i; + + /* Initialize variables */ + reg1 = reg2 = reg3 = 0; + + /* Build up column parity */ + for(i = 0; i < 256; i++) { + /* Get CP0 - CP5 from table */ + idx = nand_ecc_precalc_table[*dat++]; + reg1 ^= (idx & 0x3f); + + /* All bit XOR = 1 ? */ + if (idx & 0x40) { + reg3 ^= (uint8_t) i; + reg2 ^= ~((uint8_t) i); + } + } + + /* Create non-inverted ECC code from line parity */ + tmp1 = (reg3 & 0x80) >> 0; /* B7 -> B7 */ + tmp1 |= (reg2 & 0x80) >> 1; /* B7 -> B6 */ + tmp1 |= (reg3 & 0x40) >> 1; /* B6 -> B5 */ + tmp1 |= (reg2 & 0x40) >> 2; /* B6 -> B4 */ + tmp1 |= (reg3 & 0x20) >> 2; /* B5 -> B3 */ + tmp1 |= (reg2 & 0x20) >> 3; /* B5 -> B2 */ + tmp1 |= (reg3 & 0x10) >> 3; /* B4 -> B1 */ + tmp1 |= (reg2 & 0x10) >> 4; /* B4 -> B0 */ + + tmp2 = (reg3 & 0x08) << 4; /* B3 -> B7 */ + tmp2 |= (reg2 & 0x08) << 3; /* B3 -> B6 */ + tmp2 |= (reg3 & 0x04) << 3; /* B2 -> B5 */ + tmp2 |= (reg2 & 0x04) << 2; /* B2 -> B4 */ + tmp2 |= (reg3 & 0x02) << 2; /* B1 -> B3 */ + tmp2 |= (reg2 & 0x02) << 1; /* B1 -> B2 */ + tmp2 |= (reg3 & 0x01) << 1; /* B0 -> B1 */ + tmp2 |= (reg2 & 0x01) << 0; /* B7 -> B0 */ + + /* Calculate final ECC code */ +#ifdef CONFIG_MTD_NAND_ECC_SMC + ecc_code[0] = ~tmp2; + ecc_code[1] = ~tmp1; +#else + ecc_code[0] = ~tmp1; + ecc_code[1] = ~tmp2; +#endif + ecc_code[2] = ((~reg1) << 2) | 0x03; + + return 0; +} +EXPORT_SYMBOL(nand_calculate_ecc); + +static inline int countbits(uint32_t byte) +{ + int res = 0; + + for (;byte; byte >>= 1) + res += byte & 0x01; + return res; +} + +/** + * nand_correct_data - [NAND Interface] Detect and correct bit error(s) + * @mtd: MTD block structure + * @dat: raw data read from the chip + * @read_ecc: ECC from the chip + * @calc_ecc: the ECC calculated from raw data + * + * Detect and correct a 1 bit error for 256 byte block + */ +int nand_correct_data(struct mtd_info *mtd, u_char *dat, + u_char *read_ecc, u_char *calc_ecc) +{ + uint8_t s0, s1, s2; + +#ifdef CONFIG_MTD_NAND_ECC_SMC + s0 = calc_ecc[0] ^ read_ecc[0]; + s1 = calc_ecc[1] ^ read_ecc[1]; + s2 = calc_ecc[2] ^ read_ecc[2]; +#else + s1 = calc_ecc[0] ^ read_ecc[0]; + s0 = calc_ecc[1] ^ read_ecc[1]; + s2 = calc_ecc[2] ^ read_ecc[2]; +#endif + if ((s0 | s1 | s2) == 0) + return 0; + + /* Check for a single bit error */ + if( ((s0 ^ (s0 >> 1)) & 0x55) == 0x55 && + ((s1 ^ (s1 >> 1)) & 0x55) == 0x55 && + ((s2 ^ (s2 >> 1)) & 0x54) == 0x54) { + + uint32_t byteoffs, bitnum; + + byteoffs = (s1 << 0) & 0x80; + byteoffs |= (s1 << 1) & 0x40; + byteoffs |= (s1 << 2) & 0x20; + byteoffs |= (s1 << 3) & 0x10; + + byteoffs |= (s0 >> 4) & 0x08; + byteoffs |= (s0 >> 3) & 0x04; + byteoffs |= (s0 >> 2) & 0x02; + byteoffs |= (s0 >> 1) & 0x01; + + bitnum = (s2 >> 5) & 0x04; + bitnum |= (s2 >> 4) & 0x02; + bitnum |= (s2 >> 3) & 0x01; + + dat[byteoffs] ^= (1 << bitnum); + + return 1; + } + + if(countbits(s0 | ((uint32_t)s1 << 8) | ((uint32_t)s2 <<16)) == 1) + return 1; + + return -EBADMSG; +} +EXPORT_SYMBOL(nand_correct_data); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Steven J. Hill <sjhill@realitydiluted.com>"); +MODULE_DESCRIPTION("Generic NAND ECC support"); |