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

1 files changed, 126 insertions, 0 deletions

diff --git a/src/flash/nand_ecc.c b/src/flash/nand_ecc.c
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+/*

+ * 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 <tglx at linutronix.de>

+ *

+ * 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 <inttypes.h>

+

+#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;

+}