diff options
Diffstat (limited to 'drivers/mtd/nand/raw/nand_ecc.c')
| -rw-r--r-- | drivers/mtd/nand/raw/nand_ecc.c | 484 |
1 files changed, 484 insertions, 0 deletions
diff --git a/drivers/mtd/nand/raw/nand_ecc.c b/drivers/mtd/nand/raw/nand_ecc.c new file mode 100644 index 000000000..b6a46b1b7 --- /dev/null +++ b/drivers/mtd/nand/raw/nand_ecc.c @@ -0,0 +1,484 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * This file contains an ECC algorithm that detects and corrects 1 bit + * errors in a 256 byte block of data. + * + * 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/driver-api/mtd/nand_ecc.rst + */ + +#include <linux/types.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/mtd/mtd.h> +#include <linux/mtd/rawnand.h> +#include <linux/mtd/nand_ecc.h> +#include <asm/byteorder.h> + +/* + * 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 + * @sm_order: Smart Media byte ordering + */ +void __nand_calculate_ecc(const unsigned char *buf, unsigned int eccsize, + unsigned char *code, bool sm_order) +{ + 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 rp17; + 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 + */ + if (sm_order) { + 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]); + } + + 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); +} +EXPORT_SYMBOL(__nand_calculate_ecc); + +/** + * nand_calculate_ecc - [NAND Interface] Calculate 3-byte ECC for 256/512-byte + * block + * @chip: NAND chip object + * @buf: input buffer with raw data + * @code: output buffer with ECC + */ +int nand_calculate_ecc(struct nand_chip *chip, const unsigned char *buf, + unsigned char *code) +{ + bool sm_order = chip->ecc.options & NAND_ECC_SOFT_HAMMING_SM_ORDER; + + __nand_calculate_ecc(buf, chip->ecc.size, code, sm_order); + + return 0; +} +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) + * @sm_order: Smart Media byte order + * + * 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, bool sm_order) +{ + 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 + */ + if (sm_order) { + 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]; + } + + 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; +} +EXPORT_SYMBOL(__nand_correct_data); + +/** + * nand_correct_data - [NAND Interface] Detect and correct bit error(s) + * @chip: NAND chip object + * @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 nand_chip *chip, unsigned char *buf, + unsigned char *read_ecc, unsigned char *calc_ecc) +{ + bool sm_order = chip->ecc.options & NAND_ECC_SOFT_HAMMING_SM_ORDER; + + return __nand_correct_data(buf, read_ecc, calc_ecc, chip->ecc.size, + sm_order); +} +EXPORT_SYMBOL(nand_correct_data); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Frans Meulenbroeks <fransmeulenbroeks@gmail.com>"); +MODULE_DESCRIPTION("Generic NAND ECC support"); |