From: oharboe Date: Thu, 2 Apr 2009 21:23:16 +0000 (+0000) Subject: Nicolas Pitre nico at cam.org software ECC computation for NAND flash X-Git-Tag: v0.2.0~1058 X-Git-Url: https://review.openocd.org/gitweb?p=openocd.git;a=commitdiff_plain;h=c3d96a3a6e483f02ab3d57dfd4ead92e54caf1b0 Nicolas Pitre nico at cam.org software ECC computation for NAND flash git-svn-id: svn://svn.berlios.de/openocd/trunk@1445 b42882b7-edfa-0310-969c-e2dbd0fdcd60 --- diff --git a/src/flash/nand_ecc.c b/src/flash/nand_ecc.c new file mode 100644 index 0000000000..27777c362c --- /dev/null +++ b/src/flash/nand_ecc.c @@ -0,0 +1,126 @@ +/* + * This file contains an ECC algorithm from Toshiba that allows for detection + * and correction of 1-bit errors in a 256 byte block of data. + * + * [ Extracted from the initial code found in some early Linux versions. + * The current Linux code is bigger while being faster, but this is of + * no real benefit when the bottleneck largely remains the JTAG link. ] + * + * Copyright (C) 2000-2004 Steven J. Hill (sjhill at realitydiluted.com) + * Toshiba America Electronics Components, Inc. + * + * Copyright (C) 2006 Thomas Gleixner + * + * 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. + */ + +#ifdef HAVE_CONFIG_H +#include "config.h" +#endif + +#include "replacements.h" + +#include + +#include "nand.h" + +/* + * Pre-calculated 256-way 1 byte column parity + */ +static const u8 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 - Calculate 3-byte ECC for 256-byte block + */ +int nand_calculate_ecc(struct nand_device_s *device, const u8 *dat, u8 *ecc_code) +{ + u8 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 ^= (u8) i; + reg2 ^= ~((u8) 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 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; +}