diff options
Diffstat (limited to 'linux-2.4.x/drivers/mtd/nand/nand_ecc.c')
| -rw-r--r-- | linux-2.4.x/drivers/mtd/nand/nand_ecc.c | 101 |
1 files changed, 69 insertions, 32 deletions
diff --git a/linux-2.4.x/drivers/mtd/nand/nand_ecc.c b/linux-2.4.x/drivers/mtd/nand/nand_ecc.c index 8149559..40ac909 100644 --- a/linux-2.4.x/drivers/mtd/nand/nand_ecc.c +++ b/linux-2.4.x/drivers/mtd/nand/nand_ecc.c @@ -1,22 +1,44 @@ /* - * drivers/mtd/nand_ecc.c + * This file contains an ECC algorithm from Toshiba that detects and + * corrects 1 bit errors in a 256 byte block of data. * - * Copyright (C) 2000 Steven J. Hill (sjhill@cotw.com) - * Toshiba America Electronics Components, Inc. + * drivers/mtd/nand/nand_ecc.c * - * $Id: nand_ecc.c,v 1.7 2002/03/21 14:13:50 dwmw2 Exp $ + * Copyright (C) 2000-2004 Steven J. Hill (sjhill@realitydiluted.com) + * Toshiba America Electronics Components, Inc. * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License version 2 as - * published by the Free Software Foundation. + * $Id: nand_ecc.c,v 1.15 2005/11/07 11:14:30 gleixner Exp $ * - * This file contains an ECC algorithm from Toshiba that detects and - * corrects 1 bit errors in a 256 byte block of data. + * 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 <linux/kernel.h> #include <linux/module.h> +#include <linux/mtd/nand_ecc.h> /* * Pre-calculated 256-way 1 byte column parity @@ -41,18 +63,23 @@ static const u_char nand_ecc_precalc_table[] = { }; -/* +/** + * nand_trans_result - [GENERIC] create non-inverted ECC + * @reg2: line parity reg 2 + * @reg3: line parity reg 3 + * @ecc_code: ecc + * * Creates non-inverted ECC code from line parity */ static void nand_trans_result(u_char reg2, u_char reg3, u_char *ecc_code) { u_char a, b, i, tmp1, tmp2; - + /* Initialize variables */ a = b = 0x80; tmp1 = tmp2 = 0; - + /* Calculate first ECC byte */ for (i = 0; i < 4; i++) { if (reg3 & a) /* LP15,13,11,9 --> ecc_code[0] */ @@ -63,7 +90,7 @@ static void nand_trans_result(u_char reg2, u_char reg3, b >>= 1; a >>= 1; } - + /* Calculate second ECC byte */ b = 0x80; for (i = 0; i < 4; i++) { @@ -75,59 +102,69 @@ static void nand_trans_result(u_char reg2, u_char reg3, b >>= 1; a >>= 1; } - + /* Store two of the ECC bytes */ ecc_code[0] = tmp1; ecc_code[1] = tmp2; } -/* - * Calculate 3 byte ECC code for 256 byte block +/** + * nand_calculate_ecc - [NAND Interface] Calculate 3 byte ECC code for 256 byte block + * @mtd: MTD block structure + * @dat: raw data + * @ecc_code: buffer for ECC */ -void nand_calculate_ecc (const u_char *dat, u_char *ecc_code) +int nand_calculate_ecc(struct mtd_info *mtd, const u_char *dat, u_char *ecc_code) { u_char idx, reg1, reg2, reg3; int j; - + /* Initialize variables */ reg1 = reg2 = reg3 = 0; ecc_code[0] = ecc_code[1] = ecc_code[2] = 0; - - /* Build up column parity */ + + /* Build up column parity */ for(j = 0; j < 256; j++) { - + /* Get CP0 - CP5 from table */ idx = nand_ecc_precalc_table[dat[j]]; reg1 ^= (idx & 0x3f); - + /* All bit XOR = 1 ? */ if (idx & 0x40) { reg3 ^= (u_char) j; reg2 ^= ~((u_char) j); } } - + /* Create non-inverted ECC code from line parity */ nand_trans_result(reg2, reg3, ecc_code); - + /* Calculate final ECC code */ ecc_code[0] = ~ecc_code[0]; ecc_code[1] = ~ecc_code[1]; ecc_code[2] = ((~reg1) << 2) | 0x03; + return 0; } -/* +/** + * 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 (u_char *dat, u_char *read_ecc, u_char *calc_ecc) +int nand_correct_data(struct mtd_info *mtd, u_char *dat, u_char *read_ecc, u_char *calc_ecc) { u_char a, b, c, d1, d2, d3, add, bit, i; - - /* Do error detection */ + + /* Do error detection */ d1 = calc_ecc[0] ^ read_ecc[0]; d2 = calc_ecc[1] ^ read_ecc[1]; d3 = calc_ecc[2] ^ read_ecc[2]; - + if ((d1 | d2 | d3) == 0) { /* No errors */ return 0; @@ -136,7 +173,7 @@ int nand_correct_data (u_char *dat, u_char *read_ecc, u_char *calc_ecc) a = (d1 ^ (d1 >> 1)) & 0x55; b = (d2 ^ (d2 >> 1)) & 0x55; c = (d3 ^ (d3 >> 1)) & 0x54; - + /* Found and will correct single bit error in the data */ if ((a == 0x55) && (b == 0x55) && (c == 0x54)) { c = 0x80; @@ -200,7 +237,7 @@ int nand_correct_data (u_char *dat, u_char *read_ecc, u_char *calc_ecc) } } } - + /* Should never happen */ return -1; } @@ -209,5 +246,5 @@ EXPORT_SYMBOL(nand_calculate_ecc); EXPORT_SYMBOL(nand_correct_data); MODULE_LICENSE("GPL"); -MODULE_AUTHOR("Steven J. Hill <sjhill@cotw.com>"); +MODULE_AUTHOR("Steven J. Hill <sjhill@realitydiluted.com>"); MODULE_DESCRIPTION("Generic NAND ECC support"); |