From f12a9473283e68ae708e9ada37cb352ea2652397 Mon Sep 17 00:00:00 2001 From: Sneha Narnakaje Date: Fri, 18 Sep 2009 12:51:48 -0700 Subject: mtd: nand: DaVinci: Add 4-bit ECC support for large page NAND chips This patch adds 4-bit ECC support for large page NAND chips using the new ECC mode NAND_ECC_HW_OOB_FIRST. The platform data from board-dm355-evm has been adjusted to use this mode. The patches have been verified on DM355 device with 2KiB-page Micron devices using mtd-tests and JFFS2. Error correction up to 4 bits has also been verified using nandwrite/nanddump utilities. Reviewed-by: David Brownell Signed-off-by: Sneha Narnakaje Signed-off-by: Sandeep Paulraj Cc: Thomas Gleixner Cc: Troy Kisky Signed-off-by: Andrew Morton Signed-off-by: David Woodhouse --- drivers/mtd/nand/davinci_nand.c | 45 +++++++++++++++++++++++++++++++++++------ 1 file changed, 39 insertions(+), 6 deletions(-) (limited to 'drivers/mtd') diff --git a/drivers/mtd/nand/davinci_nand.c b/drivers/mtd/nand/davinci_nand.c index 0fad6487e6f..f13f5b9afaf 100644 --- a/drivers/mtd/nand/davinci_nand.c +++ b/drivers/mtd/nand/davinci_nand.c @@ -348,6 +348,12 @@ compare: if (!(syndrome[0] | syndrome[1] | syndrome[2] | syndrome[3])) return 0; + /* + * Clear any previous address calculation by doing a dummy read of an + * error address register. + */ + davinci_nand_readl(info, NAND_ERR_ADD1_OFFSET); + /* Start address calculation, and wait for it to complete. * We _could_ start reading more data while this is working, * to speed up the overall page read. @@ -359,8 +365,10 @@ compare: switch ((fsr >> 8) & 0x0f) { case 0: /* no error, should not happen */ + davinci_nand_readl(info, NAND_ERR_ERRVAL1_OFFSET); return 0; case 1: /* five or more errors detected */ + davinci_nand_readl(info, NAND_ERR_ERRVAL1_OFFSET); return -EIO; case 2: /* error addresses computed */ case 3: @@ -500,6 +508,26 @@ static struct nand_ecclayout hwecc4_small __initconst = { }, }; +/* An ECC layout for using 4-bit ECC with large-page (2048bytes) flash, + * storing ten ECC bytes plus the manufacturer's bad block marker byte, + * and not overlapping the default BBT markers. + */ +static struct nand_ecclayout hwecc4_2048 __initconst = { + .eccbytes = 40, + .eccpos = { + /* at the end of spare sector */ + 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, + 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, + 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, + 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, + }, + .oobfree = { + /* 2 bytes at offset 0 hold manufacturer badblock markers */ + {.offset = 2, .length = 22, }, + /* 5 bytes at offset 8 hold BBT markers */ + /* 8 bytes at offset 16 hold JFFS2 clean markers */ + }, +}; static int __init nand_davinci_probe(struct platform_device *pdev) { @@ -690,15 +718,20 @@ static int __init nand_davinci_probe(struct platform_device *pdev) info->mtd.oobsize - 16; goto syndrome_done; } + if (chunks == 4) { + info->ecclayout = hwecc4_2048; + info->chip.ecc.mode = NAND_ECC_HW_OOB_FIRST; + goto syndrome_done; + } - /* For large page chips we'll be wanting to use a - * not-yet-implemented mode that reads OOB data - * before reading the body of the page, to avoid - * the "infix OOB" model of NAND_ECC_HW_SYNDROME - * (and preserve manufacturer badblock markings). + /* 4KiB page chips are not yet supported. The eccpos from + * nand_ecclayout cannot hold 80 bytes and change to eccpos[] + * breaks userspace ioctl interface with mtd-utils. Once we + * resolve this issue, NAND_ECC_HW_OOB_FIRST mode can be used + * for the 4KiB page chips. */ dev_warn(&pdev->dev, "no 4-bit ECC support yet " - "for large page NAND\n"); + "for 4KiB-page NAND\n"); ret = -EIO; goto err_scan; -- cgit v1.2.3