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Release 4.11 drivers/mtd/nand/nand_ecc.c

Directory: drivers/mtd/nand
/*
 * 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 © 2008 Koninklijke Philips Electronics NV.
 *                  Author: Frans Meulenbroeks
 *
 * 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
 * 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.
 *
 */

/*
 * 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 pr_err printf
#endif

/*
 * 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 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
};

/*
 * bitsperbyte contains the number of bits per byte
 * this is only used for testing and repairing parity
 * (a precalculated value slightly improves performance)
 */

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,
};

/*
 * 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 for 256/512-byte
 *                       block
 * @buf:        input buffer with raw data
 * @eccsize:    data bytes per ECC step (256 or 512)
 * @code:       output buffer with ECC
 */

void __nand_calculate_ecc(const unsigned char *buf, unsigned int eccsize, unsigned char *code) { int i; const uint32_t *bp = (uint32_t *)buf; /* 256 or 512 bytes/ecc */ const uint32_t eccsize_mult = eccsize >> 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; 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; cur = *bp++; tmppar ^= cur; rp4 ^= cur; rp6 ^= cur; cur = *bp++; tmppar ^= cur; rp6 ^= cur; cur = *bp++; tmppar ^= cur; rp4 ^= cur; cur = *bp++; tmppar ^= cur; par ^= tmppar; if ((i & 0x1) == 0) rp12 ^= tmppar; if ((i & 0x2) == 0) rp14 ^= tmppar; if (eccsize_mult == 2 && (i & 0x4) == 0) rp16 ^= tmppar; } /* * 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; } /* * 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; /* * 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); }

Contributors

PersonTokensPropCommitsCommitProp
Frans Meulenbroeks103680.00%233.33%
Vimal Singh18714.44%116.67%
Thomas Gleixner634.86%116.67%
Akinobu Mita80.62%116.67%
Brian Norris10.08%116.67%
Total1295100.00%6100.00%

EXPORT_SYMBOL(__nand_calculate_ecc); /** * nand_calculate_ecc - [NAND Interface] Calculate 3-byte ECC for 256/512-byte * block * @mtd: MTD block structure * @buf: input buffer with raw data * @code: output buffer with ECC */
int nand_calculate_ecc(struct mtd_info *mtd, const unsigned char *buf, unsigned char *code) { __nand_calculate_ecc(buf, mtd_to_nand(mtd)->ecc.size, code); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Akinobu Mita3382.50%133.33%
Thomas Gleixner410.00%133.33%
Boris Brezillon37.50%133.33%
Total40100.00%3100.00%

EXPORT_SYMBOL(nand_calculate_ecc); /** * __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 eccsize byte block */
int __nand_correct_data(unsigned char *buf, unsigned char *read_ecc, unsigned char *calc_ecc, unsigned int eccsize) { unsigned char b0, b1, b2, bit_addr; unsigned int byte_addr; /* 256 or 512 bytes/ecc */ const uint32_t eccsize_mult = eccsize >> 8; /* * 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; } /* 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 */ pr_err("%s: uncorrectable ECC error\n", __func__); return -EBADMSG; }

Contributors

PersonTokensPropCommitsCommitProp
Frans Meulenbroeks14443.24%215.38%
Linus Torvalds7723.12%17.69%
Vimal Singh7321.92%215.38%
Thomas Gleixner257.51%17.69%
Atsushi Nemoto61.80%17.69%
Tormod Volden30.90%17.69%
Raphaël Poggi10.30%17.69%
André Goddard Rosa10.30%17.69%
Boris Brezillon10.30%17.69%
Brian Norris10.30%17.69%
Timo Lindhorst10.30%17.69%
Total333100.00%13100.00%

EXPORT_SYMBOL(__nand_correct_data); /** * 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, mtd_to_nand(mtd)->ecc.size); }

Contributors

PersonTokensPropCommitsCommitProp
Atsushi Nemoto4193.18%150.00%
Boris Brezillon36.82%150.00%
Total44100.00%2100.00%

EXPORT_SYMBOL(nand_correct_data); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Frans Meulenbroeks <fransmeulenbroeks@gmail.com>"); MODULE_DESCRIPTION("Generic NAND ECC support");

Overall Contributors

PersonTokensPropCommitsCommitProp
Frans Meulenbroeks251974.35%210.00%
Linus Torvalds36010.63%210.00%
Vimal Singh2667.85%210.00%
Thomas Gleixner1002.95%15.00%
Atsushi Nemoto531.56%15.00%
Akinobu Mita471.39%15.00%
Dave Jones140.41%210.00%
David Woodhouse100.30%210.00%
Boris Brezillon70.21%210.00%
Brian Norris50.15%15.00%
Tormod Volden40.12%15.00%
Timo Lindhorst10.03%15.00%
André Goddard Rosa10.03%15.00%
Raphaël Poggi10.03%15.00%
Total3388100.00%20100.00%
Directory: drivers/mtd/nand
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