[PATCH 2/3] MTD: NAND: fsl_elbc_nand: implement support for flash-based BBT

Anton Vorontsov
2008-06-27T19:04:14Z

This patch implements support for flash-based BBT for chips working
through ELBC NAND controller, so that NAND core will not have to re-scan
for bad blocks on every boot.

Because ELBC controller may provide HW-generated ECCs we should adjust
bbt pattern and bbt version positions in the OOB free area.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Acked-by: Scott Wood <scottwood@freescale.com>
---
drivers/mtd/nand/fsl_elbc_nand.c | 34 +++++++++++++++++++++++++++++++++-
1 files changed, 33 insertions(+), 1 deletions(-)

diff --git a/drivers/mtd/nand/fsl_elbc_nand.c b/drivers/mtd/nand/fsl_elbc_nand.c
index 99dc2be..5f1bc5e 100644
--- a/drivers/mtd/nand/fsl_elbc_nand.c
+++ b/drivers/mtd/nand/fsl_elbc_nand.c
@@ -130,6 +130,34 @@ static struct nand_bbt_descr largepage_memorybased = {
.pattern = scan_ff_pattern,
};

+/*
+ * ELBC may use HW ECC, so that OOB offsets, that NAND core uses for bbt,
+ * interfere with ECC positions, that's why we implement our own descriptors.
+ * OOB {11, 5}, works for both SP and LP chips, with ECCM = 1 and ECCM = 0.
+ */
+static u8 bbt_pattern[] = {'B', 'b', 't', '0' };
+static u8 mirror_pattern[] = {'1', 't', 'b', 'B' };
+
+static struct nand_bbt_descr bbt_main_descr = {
+ .options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE |
+ NAND_BBT_2BIT | NAND_BBT_VERSION,
+ .offs = 11,
+ .len = 4,
+ .veroffs = 15,
+ .maxblocks = 4,
+ .pattern = bbt_pattern,
+};
+
+static struct nand_bbt_descr bbt_mirror_descr = {
+ .options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE |
+ NAND_BBT_2BIT | NAND_BBT_VERSION,
+ .offs = 11,
+ .len = 4,
+ .veroffs = 15,
+ .maxblocks = 4,
+ .pattern = mirror_pattern,
+};
+
/*=================================*/

/*
@@ -767,8 +795,12 @@ static int fsl_elbc_chip_init(struct fsl_elbc_mtd *priv)
chip->cmdfunc = fsl_elbc_cmdfunc;
chip->waitfunc = fsl_elbc_wait;

+ chip->bbt_td = &bbt_main_descr;
+ chip->bbt_md = &bbt_mirror_descr;
+
/* set up nand options */
- chip->options = NAND_NO_READRDY | NAND_NO_AUTOINCR;
+ chip->options = NAND_NO_READRDY | NAND_NO_AUTOINCR |
+ NAND_USE_FLASH_BBT;

chip->controller = &ctrl->controller;
chip->priv = priv;
--
1.5.5.4