From e0b58d0a7005cd4b9c7fa4694a437a2d86719c13 Mon Sep 17 00:00:00 2001
From: Maxim Levitsky <maximlevitsky@gmail.com>
Date: Mon, 22 Feb 2010 20:39:38 +0200
Subject: [PATCH] mtd: nand: add ->badblockbits for minimum number of set bits
in bad block byte
This can be used to protect against bitflips in that field, but now mostly
for smartmedia.
Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
---
drivers/mtd/nand/nand_base.c | 13 +++++++++----
include/linux/mtd/nand.h | 1 +
2 files changed, 10 insertions(+), 4 deletions(-)
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 51dfea1b3ce6..ba29a29bd743 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -364,14 +364,18 @@ static int nand_block_bad(struct mtd_info *mtd, loff_t ofs, int getchip)
bad = cpu_to_le16(chip->read_word(mtd));
if (chip->badblockpos & 0x1)
bad >>= 8;
- if ((bad & 0xFF) != 0xff)
- res = 1;
+ else
+ bad &= 0xFF;
} else {
chip->cmdfunc(mtd, NAND_CMD_READOOB, chip->badblockpos, page);
- if (chip->read_byte(mtd) != 0xff)
- res = 1;
+ bad = chip->read_byte(mtd);
}
+ if (likely(chip->badblockbits == 8))
+ res = bad != 0xFF;
+ else
+ res = hweight8(bad) < chip->badblockbits;
+
if (getchip)
nand_release_device(mtd);
@@ -2884,6 +2888,7 @@ static struct nand_flash_dev *nand_get_flash_type(struct mtd_info *mtd,
/* Set the bad block position */
chip->badblockpos = mtd->writesize > 512 ?
NAND_LARGE_BADBLOCK_POS : NAND_SMALL_BADBLOCK_POS;
+ chip->badblockbits = 8;
/* Get chip options, preserve non chip based options */
chip->options &= ~NAND_CHIPOPTIONS_MSK;
diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
index 48bc2c54302c..f2d4a1ac14b8 100644
--- a/include/linux/mtd/nand.h
+++ b/include/linux/mtd/nand.h
@@ -401,6 +401,7 @@ struct nand_chip {
int subpagesize;
uint8_t cellinfo;
int badblockpos;
+ int badblockbits;
flstate_t state;