Rewrite of NAND code based on what is in 2.6.12 Linux kernel

Patch by Ladislav Michl, 29 Jun 2005

1 files changed, 244 insertions, 0 deletions

diff --git a/drivers/nand/nand_ecc.c b/drivers/nand/nand_ecc.c
new file mode 100644
index 0000000..dc9db4b
--- /dev/null
+++ b/drivers/nand/nand_ecc.c
@@ -0,0 +1,244 @@
+/*
+ * 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 (CONFIG_COMMANDS & CFG_CMD_NAND)
+
+/*
+ * 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_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] */
+			tmp1 |= b;
+		b >>= 1;
+		if (reg2 & a)		/* LP14,12,10,8 --> ecc_code[0] */
+			tmp1 |= b;
+		b >>= 1;
+		a >>= 1;
+	}
+	
+	/* Calculate second ECC byte */
+	b = 0x80;
+	for (i = 0; i < 4; i++) {
+		if (reg3 & a)		/* LP7,5,3,1 --> ecc_code[1] */
+			tmp2 |= b;
+		b >>= 1;
+		if (reg2 & a)		/* LP6,4,2,0 --> ecc_code[1] */
+			tmp2 |= b;
+		b >>= 1;
+		a >>= 1;
+	}
+	
+	/* Store two of the ECC bytes */
+	ecc_code[0] = tmp1;
+	ecc_code[1] = tmp2;
+}
+
+/**
+ * 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
+ */
+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 */ 
+	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(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 */ 
+	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;
+	}
+	else {
+		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;
+			add = 0;
+			a = 0x80;
+			for (i=0; i<4; i++) {
+				if (d1 & c)
+					add |= a;
+				c >>= 2;
+				a >>= 1;
+			}
+			c = 0x80;
+			for (i=0; i<4; i++) {
+				if (d2 & c)
+					add |= a;
+				c >>= 2;
+				a >>= 1;
+			}
+			bit = 0;
+			b = 0x04;
+			c = 0x80;
+			for (i=0; i<3; i++) {
+				if (d3 & c)
+					bit |= b;
+				c >>= 2;
+				b >>= 1;
+			}
+			b = 0x01;
+			a = dat[add];
+			a ^= (b << bit);
+			dat[add] = a;
+			return 1;
+		}
+		else {
+			i = 0;
+			while (d1) {
+				if (d1 & 0x01)
+					++i;
+				d1 >>= 1;
+			}
+			while (d2) {
+				if (d2 & 0x01)
+					++i;
+				d2 >>= 1;
+			}
+			while (d3) {
+				if (d3 & 0x01)
+					++i;
+				d3 >>= 1;
+			}
+			if (i == 1) {
+				/* ECC Code Error Correction */
+				read_ecc[0] = calc_ecc[0];
+				read_ecc[1] = calc_ecc[1];
+				read_ecc[2] = calc_ecc[2];
+				return 2;
+			}
+			else {
+				/* Uncorrectable Error */
+				return -1;
+			}
+		}
+	}
+	
+	/* Should never happen */
+	return -1;
+}
+
+#endif	/* CONFIG_COMMANDS & CFG_CMD_NAND */