/* * 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. * * $Id: nand_ecc.c,v 1.14 2004/06/16 15:34:37 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 <common.h>#if defined(CONFIG_CMD_NAND) && !defined(CFG_NAND_LEGACY)#include<linux/mtd/mtd.h>/* * NAND-SPL has no sofware ECC for now, so don't include nand_calculate_ecc(), * only nand_correct_data() is needed */#ifndef CONFIG_NAND_SPL/* * 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;}#endif /* CONFIG_NAND_SPL */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 -1;}#endif