/*
- * drivers/mtd/nand_ecc.c
+ * This file contains an ECC algorithm from Toshiba that detects and
+ * corrects 1 bit errors in a 256 byte block of data.
*
- * Copyright (C) 2000 Steven J. Hill (sjhill@realitydiluted.com)
- * Toshiba America Electronics Components, Inc.
+ * drivers/mtd/nand/nand_ecc.c
*
- * $Id: nand_ecc.c,v 1.9 2003/02/20 13:34:19 sjhill Exp $
+ * Copyright (C) 2000-2004 Steven J. Hill (sjhill@realitydiluted.com)
+ * Toshiba America Electronics Components, Inc.
*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public License
- * version 2.1 as published by the Free Software Foundation.
+ * $Id: nand_ecc.c,v 1.15 2005/11/07 11:14:30 gleixner Exp $
*
- * This file contains an ECC algorithm from Toshiba that detects and
- * corrects 1 bit errors in a 256 byte block of data.
+ * 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 <linux/types.h>
#include <linux/kernel.h>
#include <linux/module.h>
+#include <linux/mtd/nand_ecc.h>
/*
* Pre-calculated 256-way 1 byte column parity
};
-/*
+/**
+ * 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] */
b >>= 1;
a >>= 1;
}
-
+
/* Calculate second ECC byte */
b = 0x80;
for (i = 0; i < 4; i++) {
b >>= 1;
a >>= 1;
}
-
+
/* Store two of the ECC bytes */
ecc_code[0] = tmp1;
ecc_code[1] = tmp2;
}
-/*
- * Calculate 3 byte ECC code for 256 byte block
+/**
+ * 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
*/
-void nand_calculate_ecc (const u_char *dat, u_char *ecc_code)
+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 */
+
+ /* 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 (u_char *dat, u_char *read_ecc, u_char *calc_ecc)
+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 */
+
+ /* 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;
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;
}
}
}
-
+
/* Should never happen */
return -1;
}
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