From f83b7f9e8a5d1334e24506ea5953dd871596ea8a Mon Sep 17 00:00:00 2001 From: Sandeep Paulraj Date: Mon, 10 Aug 2009 13:27:56 -0400 Subject: MTD:NAND: ADD new ECC mode NAND_ECC_HW_OOB_FIRST This patch adds the new mode NAND_ECC_HW_OOB_FIRST in the nand code to support 4-bit ECC on TI DaVinci devices with large page (up to 2K) NAND chips. This ECC mode is similar to NAND_ECC_HW, with the exception of read_page API that first reads the OOB area, reads the data in chunks, feeds the ECC from OOB area to the ECC hw engine and perform any correction on the data as per the ECC status reported by the engine. This patch has been accepted by Andrew Morton and can be found at http://userweb.kernel.org/~akpm/mmotm/broken-out/mtd-nand-add-new-ecc-mode-ecc_hw_oob_first.patch Signed-off-by: Sandeep Paulraj Signed-off-by: Sneha Narnakaje Signed-off-by: Scott Wood --- drivers/mtd/nand/nand_base.c | 59 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 59 insertions(+) (limited to 'drivers') diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c index ca026286f2..426bb95e9e 100644 --- a/drivers/mtd/nand/nand_base.c +++ b/drivers/mtd/nand/nand_base.c @@ -1067,6 +1067,54 @@ static int nand_read_page_hwecc(struct mtd_info *mtd, struct nand_chip *chip, return 0; } +/** + * nand_read_page_hwecc_oob_first - [REPLACABLE] hw ecc, read oob first + * @mtd: mtd info structure + * @chip: nand chip info structure + * @buf: buffer to store read data + * + * Hardware ECC for large page chips, require OOB to be read first. + * For this ECC mode, the write_page method is re-used from ECC_HW. + * These methods read/write ECC from the OOB area, unlike the + * ECC_HW_SYNDROME support with multiple ECC steps, follows the + * "infix ECC" scheme and reads/writes ECC from the data area, by + * overwriting the NAND manufacturer bad block markings. + */ +static int nand_read_page_hwecc_oob_first(struct mtd_info *mtd, + struct nand_chip *chip, uint8_t *buf, int page) +{ + int i, eccsize = chip->ecc.size; + int eccbytes = chip->ecc.bytes; + int eccsteps = chip->ecc.steps; + uint8_t *p = buf; + uint8_t *ecc_code = chip->buffers->ecccode; + uint32_t *eccpos = chip->ecc.layout->eccpos; + uint8_t *ecc_calc = chip->buffers->ecccalc; + + /* Read the OOB area first */ + chip->cmdfunc(mtd, NAND_CMD_READOOB, 0, page); + chip->read_buf(mtd, chip->oob_poi, mtd->oobsize); + chip->cmdfunc(mtd, NAND_CMD_READ0, 0, page); + + for (i = 0; i < chip->ecc.total; i++) + ecc_code[i] = chip->oob_poi[eccpos[i]]; + + for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize) { + int stat; + + chip->ecc.hwctl(mtd, NAND_ECC_READ); + chip->read_buf(mtd, p, eccsize); + chip->ecc.calculate(mtd, p, &ecc_calc[i]); + + stat = chip->ecc.correct(mtd, p, &ecc_code[i], NULL); + if (stat < 0) + mtd->ecc_stats.failed++; + else + mtd->ecc_stats.corrected += stat; + } + return 0; +} + /** * nand_read_page_syndrome - [REPLACABLE] hardware ecc syndrom based page read * @mtd: mtd info structure @@ -2730,6 +2778,17 @@ int nand_scan_tail(struct mtd_info *mtd) chip->ecc.write_page_raw = nand_write_page_raw; switch (chip->ecc.mode) { + case NAND_ECC_HW_OOB_FIRST: + /* Similar to NAND_ECC_HW, but a separate read_page handle */ + if (!chip->ecc.calculate || !chip->ecc.correct || + !chip->ecc.hwctl) { + printk(KERN_WARNING "No ECC functions supplied, " + "Hardware ECC not possible\n"); + BUG(); + } + if (!chip->ecc.read_page) + chip->ecc.read_page = nand_read_page_hwecc_oob_first; + case NAND_ECC_HW: /* Use standard hwecc read page function ? */ if (!chip->ecc.read_page) -- cgit v1.2.3