diff options
| -rw-r--r-- | drivers/mtd/nand/Kconfig | 4 | ||||
| -rw-r--r-- | drivers/mtd/nand/s3c2410.c | 71 |
2 files changed, 62 insertions, 13 deletions
diff --git a/drivers/mtd/nand/Kconfig b/drivers/mtd/nand/Kconfig index 9326a56f0fb..143a7f04825 100644 --- a/drivers/mtd/nand/Kconfig +++ b/drivers/mtd/nand/Kconfig @@ -126,10 +126,6 @@ config MTD_NAND_S3C2410_HWECC incorrect ECC generation, and if using these, the default of software ECC is preferable. - If you lay down a device with the hardware ECC, then you will - currently not be able to switch to software, as there is no - implementation for ECC method used by the S3C2410 - config MTD_NAND_NDFC tristate "NDFC NanD Flash Controller" depends on MTD_NAND && 44x diff --git a/drivers/mtd/nand/s3c2410.c b/drivers/mtd/nand/s3c2410.c index 8b3203571ee..e8e030171ec 100644 --- a/drivers/mtd/nand/s3c2410.c +++ b/drivers/mtd/nand/s3c2410.c @@ -337,17 +337,69 @@ static int s3c2412_nand_devready(struct mtd_info *mtd) static int s3c2410_nand_correct_data(struct mtd_info *mtd, u_char *dat, u_char *read_ecc, u_char *calc_ecc) { - pr_debug("s3c2410_nand_correct_data(%p,%p,%p,%p)\n", mtd, dat, read_ecc, calc_ecc); + struct s3c2410_nand_info *info = s3c2410_nand_mtd_toinfo(mtd); + unsigned int diff0, diff1, diff2; + unsigned int bit, byte; - pr_debug("eccs: read %02x,%02x,%02x vs calc %02x,%02x,%02x\n", - read_ecc[0], read_ecc[1], read_ecc[2], calc_ecc[0], calc_ecc[1], calc_ecc[2]); + pr_debug("%s(%p,%p,%p,%p)\n", __func__, mtd, dat, read_ecc, calc_ecc); - if (read_ecc[0] == calc_ecc[0] && read_ecc[1] == calc_ecc[1] && read_ecc[2] == calc_ecc[2]) - return 0; + diff0 = read_ecc[0] ^ calc_ecc[0]; + diff1 = read_ecc[1] ^ calc_ecc[1]; + diff2 = read_ecc[2] ^ calc_ecc[2]; + + pr_debug("%s: rd %02x%02x%02x calc %02x%02x%02x diff %02x%02x%02x\n", + __func__, + read_ecc[0], read_ecc[1], read_ecc[2], + calc_ecc[0], calc_ecc[1], calc_ecc[2], + diff0, diff1, diff2); + + if (diff0 == 0 && diff1 == 0 && diff2 == 0) + return 0; /* ECC is ok */ + + /* Can we correct this ECC (ie, one row and column change). + * Note, this is similar to the 256 error code on smartmedia */ + + if (((diff0 ^ (diff0 >> 1)) & 0x55) == 0x55 && + ((diff1 ^ (diff1 >> 1)) & 0x55) == 0x55 && + ((diff2 ^ (diff2 >> 1)) & 0x55) == 0x55) { + /* calculate the bit position of the error */ + + bit = (diff2 >> 2) & 1; + bit |= (diff2 >> 3) & 2; + bit |= (diff2 >> 4) & 4; + + /* calculate the byte position of the error */ + + byte = (diff1 << 1) & 0x80; + byte |= (diff1 << 2) & 0x40; + byte |= (diff1 << 3) & 0x20; + byte |= (diff1 << 4) & 0x10; - /* we curently have no method for correcting the error */ + byte |= (diff0 >> 3) & 0x08; + byte |= (diff0 >> 2) & 0x04; + byte |= (diff0 >> 1) & 0x02; + byte |= (diff0 >> 0) & 0x01; - return -1; + byte |= (diff2 << 8) & 0x100; + + dev_dbg(info->device, "correcting error bit %d, byte %d\n", + bit, byte); + + dat[byte] ^= (1 << bit); + return 1; + } + + /* if there is only one bit difference in the ECC, then + * one of only a row or column parity has changed, which + * means the error is most probably in the ECC itself */ + + diff0 |= (diff1 << 8); + diff0 |= (diff2 << 16); + + if ((diff0 & ~(1<<fls(diff0))) == 0) + return 1; + + return 0; } /* ECC functions @@ -383,7 +435,8 @@ static int s3c2410_nand_calculate_ecc(struct mtd_info *mtd, const u_char *dat, u ecc_code[1] = readb(info->regs + S3C2410_NFECC + 1); ecc_code[2] = readb(info->regs + S3C2410_NFECC + 2); - pr_debug("calculate_ecc: returning ecc %02x,%02x,%02x\n", ecc_code[0], ecc_code[1], ecc_code[2]); + pr_debug("%s: returning ecc %02x%02x%02x\n", __func__, + ecc_code[0], ecc_code[1], ecc_code[2]); return 0; } @@ -397,7 +450,7 @@ static int s3c2440_nand_calculate_ecc(struct mtd_info *mtd, const u_char *dat, u ecc_code[1] = ecc >> 8; ecc_code[2] = ecc >> 16; - pr_debug("calculate_ecc: returning ecc %02x,%02x,%02x\n", ecc_code[0], ecc_code[1], ecc_code[2]); + pr_debug("%s: returning ecc %06x\n", __func__, ecc); return 0; } |