diff options
Diffstat (limited to 'drivers/mtd')
| -rw-r--r-- | drivers/mtd/nand/nand_ecc.c | 44 |
1 files changed, 33 insertions, 11 deletions
diff --git a/drivers/mtd/nand/nand_ecc.c b/drivers/mtd/nand/nand_ecc.c index a8e8413ca2b..d99e569e999 100644 --- a/drivers/mtd/nand/nand_ecc.c +++ b/drivers/mtd/nand/nand_ecc.c @@ -43,6 +43,7 @@ #include <linux/kernel.h> #include <linux/module.h> #include <linux/mtd/nand_ecc.h> +#include <asm/byteorder.h> #else #include <stdint.h> struct mtd_info; @@ -51,6 +52,9 @@ struct mtd_info; #define MODULE_LICENSE(x) /* x */ #define MODULE_AUTHOR(x) /* x */ #define MODULE_DESCRIPTION(x) /* x */ + +#define printk printf +#define KERN_ERR "" #endif /* @@ -273,24 +277,38 @@ int nand_calculate_ecc(struct mtd_info *mtd, const unsigned char *buf, /* * we also need to calculate the row parity for rp0..rp3 * This is present in par, because par is now - * rp3 rp3 rp2 rp2 + * rp3 rp3 rp2 rp2 in little endian and + * rp2 rp2 rp3 rp3 in big endian * as well as - * rp1 rp0 rp1 rp0 + * rp1 rp0 rp1 rp0 in little endian and + * rp0 rp1 rp0 rp1 in big endian * First calculate rp2 and rp3 - * (and yes: rp2 = (par ^ rp3) & 0xff; but doing that did not - * give a performance improvement) */ +#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); @@ -381,7 +399,6 @@ EXPORT_SYMBOL(nand_calculate_ecc); int nand_correct_data(struct mtd_info *mtd, unsigned char *buf, unsigned char *read_ecc, unsigned char *calc_ecc) { - int nr_bits; unsigned char b0, b1, b2; unsigned char byte_addr, bit_addr; @@ -401,14 +418,15 @@ int nand_correct_data(struct mtd_info *mtd, unsigned char *buf, /* check if there are any bitfaults */ - /* count nr of bits; use table lookup, faster than calculating it */ - nr_bits = bitsperbyte[b0] + bitsperbyte[b1] + bitsperbyte[b2]; - /* repeated if statements are slightly more efficient than switch ... */ /* ordered in order of likelihood */ - if (nr_bits == 0) + + if ((b0 | b1 | b2) == 0) return 0; /* no error */ - if (nr_bits == 11) { /* correctable error */ + + if ((((b0 ^ (b0 >> 1)) & 0x55) == 0x55) && + (((b1 ^ (b1 >> 1)) & 0x55) == 0x55) && + (((b2 ^ (b2 >> 1)) & 0x54) == 0x54)) { /* single bit error */ /* * rp15/13/11/9/7/5/3/1 indicate which byte is the faulty byte * cp 5/3/1 indicate the faulty bit. @@ -430,9 +448,13 @@ int nand_correct_data(struct mtd_info *mtd, unsigned char *buf, /* flip the bit */ buf[byte_addr] ^= (1 << bit_addr); return 1; + } - if (nr_bits == 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 */ + + printk(KERN_ERR "uncorrectable error : "); return -1; } EXPORT_SYMBOL(nand_correct_data); |