Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=a2593247d747954cd12c32da8c5a3aecb9cd19a3
Commit: a2593247d747954cd12c32da8c5a3aecb9cd19a3
Parent: a7a6ace1406f95c3edb8365788f85984377f3832
Author: Ben Dooks <[EMAIL PROTECTED]>
AuthorDate: Fri Feb 2 16:59:33 2007 +0000
Committer: David Woodhouse <[EMAIL PROTECTED]>
CommitDate: Fri Feb 9 17:12:59 2007 +0000
[MTD] [NAND] S3C2410: Hardware ECC correction code
Add support for correcting errors detected by the
hardware ECC.
Signed-off-by: Ben Dooks <[EMAIL PROTECTED]>
Signed-off-by: David Woodhouse <[EMAIL PROTECTED]>
---
drivers/mtd/nand/Kconfig | 4 --
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 9326a56..143a7f0 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 8b32035..e8e0301 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;
}
-
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