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-rw-r--r--src/flash/nand_ecc.c126
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;
+}