/*
- * This file contains an ECC algorithm from Toshiba that detects and
- * corrects 1 bit errors in a 256 byte block of data.
+ * This file contains an ECC algorithm 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.
+ * Copyright © 2008 Koninklijke Philips Electronics NV.
+ * Author: Frans Meulenbroeks
*
- * $Id: nand_ecc.c,v 1.15 2005/11/07 11:14:30 gleixner Exp $
+ * Completely replaces the previous ECC implementation which was written by:
+ * Steven J. Hill (sjhill@realitydiluted.com)
+ * Thomas Gleixner (tglx@linutronix.de)
+ *
+ * Information on how this algorithm works and how it was developed
+ * can be found in Documentation/mtd/nand_ecc.txt
*
* 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
* 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.
*/
+/*
+ * The STANDALONE macro is useful when running the code outside the kernel
+ * e.g. when running the code in a testbed or a benchmark program.
+ * When STANDALONE is used, the module related macros are commented out
+ * as well as the linux include files.
+ * Instead a private definition of mtd_info is given to satisfy the compiler
+ * (the code does not use mtd_info, so the code does not care)
+ */
+#ifndef STANDALONE
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/module.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/nand.h>
#include <linux/mtd/nand_ecc.h>
+#include <asm/byteorder.h>
+#else
+#include <stdint.h>
+struct mtd_info;
+#define EXPORT_SYMBOL(x) /* x */
+
+#define MODULE_LICENSE(x) /* x */
+#define MODULE_AUTHOR(x) /* x */
+#define MODULE_DESCRIPTION(x) /* x */
+
+#define printk printf
+#define KERN_ERR ""
+#endif
/*
- * Pre-calculated 256-way 1 byte column parity
+ * invparity is a 256 byte table that contains the odd parity
+ * for each byte. So if the number of bits in a byte is even,
+ * the array element is 1, and when the number of bits is odd
+ * the array eleemnt is 0.
*/
-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
+static const char invparity[256] = {
+ 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
+ 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
+ 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
+ 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
+ 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
+ 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
+ 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
+ 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
+ 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
+ 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
+ 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
+ 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
+ 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
+ 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
+ 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
+ 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1
};
-
-/**
- * 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
+/*
+ * bitsperbyte contains the number of bits per byte
+ * this is only used for testing and repairing parity
+ * (a precalculated value slightly improves performance)
*/
-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;
- }
+static const char bitsperbyte[256] = {
+ 0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
+ 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
+ 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
+ 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
+ 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
+ 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
+ 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
+ 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
+ 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
+ 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
+ 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
+ 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
+ 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
+ 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
+ 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
+ 4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8,
+};
- /* Store two of the ECC bytes */
- ecc_code[0] = tmp1;
- ecc_code[1] = tmp2;
-}
+/*
+ * addressbits is a lookup table to filter out the bits from the xor-ed
+ * ecc data that identify the faulty location.
+ * this is only used for repairing parity
+ * see the comments in nand_correct_data for more details
+ */
+static const char addressbits[256] = {
+ 0x00, 0x00, 0x01, 0x01, 0x00, 0x00, 0x01, 0x01,
+ 0x02, 0x02, 0x03, 0x03, 0x02, 0x02, 0x03, 0x03,
+ 0x00, 0x00, 0x01, 0x01, 0x00, 0x00, 0x01, 0x01,
+ 0x02, 0x02, 0x03, 0x03, 0x02, 0x02, 0x03, 0x03,
+ 0x04, 0x04, 0x05, 0x05, 0x04, 0x04, 0x05, 0x05,
+ 0x06, 0x06, 0x07, 0x07, 0x06, 0x06, 0x07, 0x07,
+ 0x04, 0x04, 0x05, 0x05, 0x04, 0x04, 0x05, 0x05,
+ 0x06, 0x06, 0x07, 0x07, 0x06, 0x06, 0x07, 0x07,
+ 0x00, 0x00, 0x01, 0x01, 0x00, 0x00, 0x01, 0x01,
+ 0x02, 0x02, 0x03, 0x03, 0x02, 0x02, 0x03, 0x03,
+ 0x00, 0x00, 0x01, 0x01, 0x00, 0x00, 0x01, 0x01,
+ 0x02, 0x02, 0x03, 0x03, 0x02, 0x02, 0x03, 0x03,
+ 0x04, 0x04, 0x05, 0x05, 0x04, 0x04, 0x05, 0x05,
+ 0x06, 0x06, 0x07, 0x07, 0x06, 0x06, 0x07, 0x07,
+ 0x04, 0x04, 0x05, 0x05, 0x04, 0x04, 0x05, 0x05,
+ 0x06, 0x06, 0x07, 0x07, 0x06, 0x06, 0x07, 0x07,
+ 0x08, 0x08, 0x09, 0x09, 0x08, 0x08, 0x09, 0x09,
+ 0x0a, 0x0a, 0x0b, 0x0b, 0x0a, 0x0a, 0x0b, 0x0b,
+ 0x08, 0x08, 0x09, 0x09, 0x08, 0x08, 0x09, 0x09,
+ 0x0a, 0x0a, 0x0b, 0x0b, 0x0a, 0x0a, 0x0b, 0x0b,
+ 0x0c, 0x0c, 0x0d, 0x0d, 0x0c, 0x0c, 0x0d, 0x0d,
+ 0x0e, 0x0e, 0x0f, 0x0f, 0x0e, 0x0e, 0x0f, 0x0f,
+ 0x0c, 0x0c, 0x0d, 0x0d, 0x0c, 0x0c, 0x0d, 0x0d,
+ 0x0e, 0x0e, 0x0f, 0x0f, 0x0e, 0x0e, 0x0f, 0x0f,
+ 0x08, 0x08, 0x09, 0x09, 0x08, 0x08, 0x09, 0x09,
+ 0x0a, 0x0a, 0x0b, 0x0b, 0x0a, 0x0a, 0x0b, 0x0b,
+ 0x08, 0x08, 0x09, 0x09, 0x08, 0x08, 0x09, 0x09,
+ 0x0a, 0x0a, 0x0b, 0x0b, 0x0a, 0x0a, 0x0b, 0x0b,
+ 0x0c, 0x0c, 0x0d, 0x0d, 0x0c, 0x0c, 0x0d, 0x0d,
+ 0x0e, 0x0e, 0x0f, 0x0f, 0x0e, 0x0e, 0x0f, 0x0f,
+ 0x0c, 0x0c, 0x0d, 0x0d, 0x0c, 0x0c, 0x0d, 0x0d,
+ 0x0e, 0x0e, 0x0f, 0x0f, 0x0e, 0x0e, 0x0f, 0x0f
+};
/**
- * nand_calculate_ecc - [NAND Interface] Calculate 3 byte ECC code for 256 byte block
+ * nand_calculate_ecc - [NAND Interface] Calculate 3-byte ECC for 256/512-byte
+ * block
* @mtd: MTD block structure
- * @dat: raw data
- * @ecc_code: buffer for ECC
+ * @buf: input buffer with raw data
+ * @code: output buffer with ECC
*/
-int nand_calculate_ecc(struct mtd_info *mtd, const u_char *dat, u_char *ecc_code)
+int nand_calculate_ecc(struct mtd_info *mtd, const unsigned char *buf,
+ unsigned char *code)
{
- u_char idx, reg1, reg2, reg3;
- int j;
+ int i;
+ const uint32_t *bp = (uint32_t *)buf;
+ /* 256 or 512 bytes/ecc */
+ const uint32_t eccsize_mult =
+ (((struct nand_chip *)mtd->priv)->ecc.size) >> 8;
+ uint32_t cur; /* current value in buffer */
+ /* rp0..rp15..rp17 are the various accumulated parities (per byte) */
+ uint32_t rp0, rp1, rp2, rp3, rp4, rp5, rp6, rp7;
+ uint32_t rp8, rp9, rp10, rp11, rp12, rp13, rp14, rp15, rp16;
+ uint32_t uninitialized_var(rp17); /* to make compiler happy */
+ uint32_t par; /* the cumulative parity for all data */
+ uint32_t tmppar; /* the cumulative parity for this iteration;
+ for rp12, rp14 and rp16 at the end of the
+ loop */
+
+ par = 0;
+ rp4 = 0;
+ rp6 = 0;
+ rp8 = 0;
+ rp10 = 0;
+ rp12 = 0;
+ rp14 = 0;
+ rp16 = 0;
+
+ /*
+ * The loop is unrolled a number of times;
+ * This avoids if statements to decide on which rp value to update
+ * Also we process the data by longwords.
+ * Note: passing unaligned data might give a performance penalty.
+ * It is assumed that the buffers are aligned.
+ * tmppar is the cumulative sum of this iteration.
+ * needed for calculating rp12, rp14, rp16 and par
+ * also used as a performance improvement for rp6, rp8 and rp10
+ */
+ for (i = 0; i < eccsize_mult << 2; i++) {
+ cur = *bp++;
+ tmppar = cur;
+ rp4 ^= cur;
+ cur = *bp++;
+ tmppar ^= cur;
+ rp6 ^= tmppar;
+ cur = *bp++;
+ tmppar ^= cur;
+ rp4 ^= cur;
+ cur = *bp++;
+ tmppar ^= cur;
+ rp8 ^= tmppar;
+
+ cur = *bp++;
+ tmppar ^= cur;
+ rp4 ^= cur;
+ rp6 ^= cur;
+ cur = *bp++;
+ tmppar ^= cur;
+ rp6 ^= cur;
+ cur = *bp++;
+ tmppar ^= cur;
+ rp4 ^= cur;
+ cur = *bp++;
+ tmppar ^= cur;
+ rp10 ^= tmppar;
- /* Initialize variables */
- reg1 = reg2 = reg3 = 0;
- ecc_code[0] = ecc_code[1] = ecc_code[2] = 0;
+ cur = *bp++;
+ tmppar ^= cur;
+ rp4 ^= cur;
+ rp6 ^= cur;
+ rp8 ^= cur;
+ cur = *bp++;
+ tmppar ^= cur;
+ rp6 ^= cur;
+ rp8 ^= cur;
+ cur = *bp++;
+ tmppar ^= cur;
+ rp4 ^= cur;
+ rp8 ^= cur;
+ cur = *bp++;
+ tmppar ^= cur;
+ rp8 ^= cur;
- /* Build up column parity */
- for(j = 0; j < 256; j++) {
+ cur = *bp++;
+ tmppar ^= cur;
+ rp4 ^= cur;
+ rp6 ^= cur;
+ cur = *bp++;
+ tmppar ^= cur;
+ rp6 ^= cur;
+ cur = *bp++;
+ tmppar ^= cur;
+ rp4 ^= cur;
+ cur = *bp++;
+ tmppar ^= cur;
- /* Get CP0 - CP5 from table */
- idx = nand_ecc_precalc_table[dat[j]];
- reg1 ^= (idx & 0x3f);
+ par ^= tmppar;
+ if ((i & 0x1) == 0)
+ rp12 ^= tmppar;
+ if ((i & 0x2) == 0)
+ rp14 ^= tmppar;
+ if (eccsize_mult == 2 && (i & 0x4) == 0)
+ rp16 ^= tmppar;
+ }
- /* All bit XOR = 1 ? */
- if (idx & 0x40) {
- reg3 ^= (u_char) j;
- reg2 ^= ~((u_char) j);
- }
+ /*
+ * handle the fact that we use longword operations
+ * we'll bring rp4..rp14..rp16 back to single byte entities by
+ * shifting and xoring first fold the upper and lower 16 bits,
+ * then the upper and lower 8 bits.
+ */
+ rp4 ^= (rp4 >> 16);
+ rp4 ^= (rp4 >> 8);
+ rp4 &= 0xff;
+ rp6 ^= (rp6 >> 16);
+ rp6 ^= (rp6 >> 8);
+ rp6 &= 0xff;
+ rp8 ^= (rp8 >> 16);
+ rp8 ^= (rp8 >> 8);
+ rp8 &= 0xff;
+ rp10 ^= (rp10 >> 16);
+ rp10 ^= (rp10 >> 8);
+ rp10 &= 0xff;
+ rp12 ^= (rp12 >> 16);
+ rp12 ^= (rp12 >> 8);
+ rp12 &= 0xff;
+ rp14 ^= (rp14 >> 16);
+ rp14 ^= (rp14 >> 8);
+ rp14 &= 0xff;
+ if (eccsize_mult == 2) {
+ rp16 ^= (rp16 >> 16);
+ rp16 ^= (rp16 >> 8);
+ rp16 &= 0xff;
}
- /* Create non-inverted ECC code from line parity */
- nand_trans_result(reg2, reg3, ecc_code);
+ /*
+ * we also need to calculate the row parity for rp0..rp3
+ * This is present in par, because par is now
+ * rp3 rp3 rp2 rp2 in little endian and
+ * rp2 rp2 rp3 rp3 in big endian
+ * as well as
+ * rp1 rp0 rp1 rp0 in little endian and
+ * rp0 rp1 rp0 rp1 in big endian
+ * First calculate rp2 and rp3
+ */
+#ifdef __BIG_ENDIAN
+ rp2 = (par >> 16);
+ rp2 ^= (rp2 >> 8);
+ rp2 &= 0xff;
+ rp3 = par & 0xffff;
+ rp3 ^= (rp3 >> 8);
+ rp3 &= 0xff;
+#else
+ rp3 = (par >> 16);
+ rp3 ^= (rp3 >> 8);
+ rp3 &= 0xff;
+ rp2 = par & 0xffff;
+ rp2 ^= (rp2 >> 8);
+ rp2 &= 0xff;
+#endif
+
+ /* reduce par to 16 bits then calculate rp1 and rp0 */
+ par ^= (par >> 16);
+#ifdef __BIG_ENDIAN
+ rp0 = (par >> 8) & 0xff;
+ rp1 = (par & 0xff);
+#else
+ rp1 = (par >> 8) & 0xff;
+ rp0 = (par & 0xff);
+#endif
+
+ /* finally reduce par to 8 bits */
+ par ^= (par >> 8);
+ par &= 0xff;
- /* Calculate final ECC code */
- ecc_code[0] = ~ecc_code[0];
- ecc_code[1] = ~ecc_code[1];
- ecc_code[2] = ((~reg1) << 2) | 0x03;
+ /*
+ * and calculate rp5..rp15..rp17
+ * note that par = rp4 ^ rp5 and due to the commutative property
+ * of the ^ operator we can say:
+ * rp5 = (par ^ rp4);
+ * The & 0xff seems superfluous, but benchmarking learned that
+ * leaving it out gives slightly worse results. No idea why, probably
+ * it has to do with the way the pipeline in pentium is organized.
+ */
+ rp5 = (par ^ rp4) & 0xff;
+ rp7 = (par ^ rp6) & 0xff;
+ rp9 = (par ^ rp8) & 0xff;
+ rp11 = (par ^ rp10) & 0xff;
+ rp13 = (par ^ rp12) & 0xff;
+ rp15 = (par ^ rp14) & 0xff;
+ if (eccsize_mult == 2)
+ rp17 = (par ^ rp16) & 0xff;
+
+ /*
+ * Finally calculate the ecc bits.
+ * Again here it might seem that there are performance optimisations
+ * possible, but benchmarks showed that on the system this is developed
+ * the code below is the fastest
+ */
+#ifdef CONFIG_MTD_NAND_ECC_SMC
+ code[0] =
+ (invparity[rp7] << 7) |
+ (invparity[rp6] << 6) |
+ (invparity[rp5] << 5) |
+ (invparity[rp4] << 4) |
+ (invparity[rp3] << 3) |
+ (invparity[rp2] << 2) |
+ (invparity[rp1] << 1) |
+ (invparity[rp0]);
+ code[1] =
+ (invparity[rp15] << 7) |
+ (invparity[rp14] << 6) |
+ (invparity[rp13] << 5) |
+ (invparity[rp12] << 4) |
+ (invparity[rp11] << 3) |
+ (invparity[rp10] << 2) |
+ (invparity[rp9] << 1) |
+ (invparity[rp8]);
+#else
+ code[1] =
+ (invparity[rp7] << 7) |
+ (invparity[rp6] << 6) |
+ (invparity[rp5] << 5) |
+ (invparity[rp4] << 4) |
+ (invparity[rp3] << 3) |
+ (invparity[rp2] << 2) |
+ (invparity[rp1] << 1) |
+ (invparity[rp0]);
+ code[0] =
+ (invparity[rp15] << 7) |
+ (invparity[rp14] << 6) |
+ (invparity[rp13] << 5) |
+ (invparity[rp12] << 4) |
+ (invparity[rp11] << 3) |
+ (invparity[rp10] << 2) |
+ (invparity[rp9] << 1) |
+ (invparity[rp8]);
+#endif
+ if (eccsize_mult == 1)
+ code[2] =
+ (invparity[par & 0xf0] << 7) |
+ (invparity[par & 0x0f] << 6) |
+ (invparity[par & 0xcc] << 5) |
+ (invparity[par & 0x33] << 4) |
+ (invparity[par & 0xaa] << 3) |
+ (invparity[par & 0x55] << 2) |
+ 3;
+ else
+ code[2] =
+ (invparity[par & 0xf0] << 7) |
+ (invparity[par & 0x0f] << 6) |
+ (invparity[par & 0xcc] << 5) |
+ (invparity[par & 0x33] << 4) |
+ (invparity[par & 0xaa] << 3) |
+ (invparity[par & 0x55] << 2) |
+ (invparity[rp17] << 1) |
+ (invparity[rp16] << 0);
return 0;
}
+EXPORT_SYMBOL(nand_calculate_ecc);
/**
- * nand_correct_data - [NAND Interface] Detect and correct bit error(s)
- * @mtd: MTD block structure
- * @dat: raw data read from the chip
+ * __nand_correct_data - [NAND Interface] Detect and correct bit error(s)
+ * @buf: raw data read from the chip
* @read_ecc: ECC from the chip
* @calc_ecc: the ECC calculated from raw data
+ * @eccsize: data bytes per ecc step (256 or 512)
*
- * Detect and correct a 1 bit error for 256 byte block
+ * Detect and correct a 1 bit error for eccsize byte block
*/
-int nand_correct_data(struct mtd_info *mtd, u_char *dat, u_char *read_ecc, u_char *calc_ecc)
+int __nand_correct_data(unsigned char *buf,
+ unsigned char *read_ecc, unsigned char *calc_ecc,
+ unsigned int eccsize)
{
- u_char a, b, c, d1, d2, d3, add, bit, i;
+ unsigned char b0, b1, b2, bit_addr;
+ unsigned int byte_addr;
+ /* 256 or 512 bytes/ecc */
+ const uint32_t eccsize_mult = eccsize >> 8;
- /* Do error detection */
- d1 = calc_ecc[0] ^ read_ecc[0];
- d2 = calc_ecc[1] ^ read_ecc[1];
- d3 = calc_ecc[2] ^ read_ecc[2];
+ /*
+ * b0 to b2 indicate which bit is faulty (if any)
+ * we might need the xor result more than once,
+ * so keep them in a local var
+ */
+#ifdef CONFIG_MTD_NAND_ECC_SMC
+ b0 = read_ecc[0] ^ calc_ecc[0];
+ b1 = read_ecc[1] ^ calc_ecc[1];
+#else
+ b0 = read_ecc[1] ^ calc_ecc[1];
+ b1 = read_ecc[0] ^ calc_ecc[0];
+#endif
+ b2 = read_ecc[2] ^ calc_ecc[2];
+
+ /* check if there are any bitfaults */
+
+ /* repeated if statements are slightly more efficient than switch ... */
+ /* ordered in order of likelihood */
+
+ if ((b0 | b1 | b2) == 0)
+ return 0; /* no error */
+
+ if ((((b0 ^ (b0 >> 1)) & 0x55) == 0x55) &&
+ (((b1 ^ (b1 >> 1)) & 0x55) == 0x55) &&
+ ((eccsize_mult == 1 && ((b2 ^ (b2 >> 1)) & 0x54) == 0x54) ||
+ (eccsize_mult == 2 && ((b2 ^ (b2 >> 1)) & 0x55) == 0x55))) {
+ /* single bit error */
+ /*
+ * rp17/rp15/13/11/9/7/5/3/1 indicate which byte is the faulty
+ * byte, cp 5/3/1 indicate the faulty bit.
+ * A lookup table (called addressbits) is used to filter
+ * the bits from the byte they are in.
+ * A marginal optimisation is possible by having three
+ * different lookup tables.
+ * One as we have now (for b0), one for b2
+ * (that would avoid the >> 1), and one for b1 (with all values
+ * << 4). However it was felt that introducing two more tables
+ * hardly justify the gain.
+ *
+ * The b2 shift is there to get rid of the lowest two bits.
+ * We could also do addressbits[b2] >> 1 but for the
+ * performance it does not make any difference
+ */
+ if (eccsize_mult == 1)
+ byte_addr = (addressbits[b1] << 4) + addressbits[b0];
+ else
+ byte_addr = (addressbits[b2 & 0x3] << 8) +
+ (addressbits[b1] << 4) + addressbits[b0];
+ bit_addr = addressbits[b2 >> 2];
+ /* flip the bit */
+ buf[byte_addr] ^= (1 << bit_addr);
+ return 1;
- 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;
- }
- }
}
+ /* count nr of bits; use table lookup, faster than calculating it */
+ if ((bitsperbyte[b0] + bitsperbyte[b1] + bitsperbyte[b2]) == 1)
+ return 1; /* error in ecc data; no action needed */
- /* Should never happen */
+ printk(KERN_ERR "uncorrectable error : ");
return -1;
}
+EXPORT_SYMBOL(__nand_correct_data);
-EXPORT_SYMBOL(nand_calculate_ecc);
+/**
+ * nand_correct_data - [NAND Interface] Detect and correct bit error(s)
+ * @mtd: MTD block structure
+ * @buf: 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 256/512 byte block
+ */
+int nand_correct_data(struct mtd_info *mtd, unsigned char *buf,
+ unsigned char *read_ecc, unsigned char *calc_ecc)
+{
+ return __nand_correct_data(buf, read_ecc, calc_ecc,
+ ((struct nand_chip *)mtd->priv)->ecc.size);
+}
EXPORT_SYMBOL(nand_correct_data);
MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Steven J. Hill <sjhill@realitydiluted.com>");
+MODULE_AUTHOR("Frans Meulenbroeks <fransmeulenbroeks@gmail.com>");
MODULE_DESCRIPTION("Generic NAND ECC support");
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff