From: Stefan Roese Date: Mon, 19 Oct 2015 06:40:13 +0000 (+0200) Subject: mtd: fsmc_nand: Add BCH4 SW ECC support for SPEAr600 X-Git-Tag: firefly_0821_release~176^2~766^2~13 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=e278fc71b2c63905d3631b8d7b12ab7bcba9d2be;p=firefly-linux-kernel-4.4.55.git mtd: fsmc_nand: Add BCH4 SW ECC support for SPEAr600 This patch adds support for 4-bit ECC BCH4 for the SPEAr600 SoC. This can be used by boards equipped with a NAND chip that requires 4-bit ECC strength. The SPEAr600 HW ECC only supports 1-bit ECC strength. To enable SW BCH4, you need to specify this in your nand controller DT node: nand-ecc-mode = "soft_bch"; nand-ecc-strength = <4>; nand-ecc-step-size = <512>; Tested on a custom SPEAr600 board. Signed-off-by: Stefan Roese Cc: Linus Walleij Cc: Viresh Kumar [Brian: tweaked the comments a bit] Signed-off-by: Brian Norris --- diff --git a/Documentation/devicetree/bindings/mtd/fsmc-nand.txt b/Documentation/devicetree/bindings/mtd/fsmc-nand.txt index 5235cbc551b0..32636eb77304 100644 --- a/Documentation/devicetree/bindings/mtd/fsmc-nand.txt +++ b/Documentation/devicetree/bindings/mtd/fsmc-nand.txt @@ -30,6 +30,12 @@ Optional properties: command is asserted. Zero means one cycle, 255 means 256 cycles. - bank: default NAND bank to use (0-3 are valid, 0 is the default). +- nand-ecc-mode : see nand.txt +- nand-ecc-strength : see nand.txt +- nand-ecc-step-size : see nand.txt + +Can support 1-bit HW ECC (default) or if stronger correction is required, +software-based BCH. Example: diff --git a/drivers/mtd/nand/fsmc_nand.c b/drivers/mtd/nand/fsmc_nand.c index 9e4fd0f59d3b..07af3dc7a4d2 100644 --- a/drivers/mtd/nand/fsmc_nand.c +++ b/drivers/mtd/nand/fsmc_nand.c @@ -1023,12 +1023,17 @@ static int __init fsmc_nand_probe(struct platform_device *pdev) nand->cmd_ctrl = fsmc_cmd_ctrl; nand->chip_delay = 30; + /* + * Setup default ECC mode. nand_dt_init() called from nand_scan_ident() + * can overwrite this value if the DT provides a different value. + */ nand->ecc.mode = NAND_ECC_HW; nand->ecc.hwctl = fsmc_enable_hwecc; nand->ecc.size = 512; nand->options = pdata->options; nand->select_chip = fsmc_select_chip; nand->badblockbits = 7; + nand->flash_node = np; if (pdata->width == FSMC_NAND_BW16) nand->options |= NAND_BUSWIDTH_16; @@ -1070,11 +1075,6 @@ static int __init fsmc_nand_probe(struct platform_device *pdev) nand->ecc.correct = fsmc_bch8_correct_data; nand->ecc.bytes = 13; nand->ecc.strength = 8; - } else { - nand->ecc.calculate = fsmc_read_hwecc_ecc1; - nand->ecc.correct = nand_correct_data; - nand->ecc.bytes = 3; - nand->ecc.strength = 1; } /* @@ -1115,22 +1115,47 @@ static int __init fsmc_nand_probe(struct platform_device *pdev) goto err_probe; } } else { - switch (host->mtd.oobsize) { - case 16: - nand->ecc.layout = &fsmc_ecc1_16_layout; + switch (nand->ecc.mode) { + case NAND_ECC_HW: + dev_info(&pdev->dev, "Using 1-bit HW ECC scheme\n"); + nand->ecc.calculate = fsmc_read_hwecc_ecc1; + nand->ecc.correct = nand_correct_data; + nand->ecc.bytes = 3; + nand->ecc.strength = 1; break; - case 64: - nand->ecc.layout = &fsmc_ecc1_64_layout; - break; - case 128: - nand->ecc.layout = &fsmc_ecc1_128_layout; + + case NAND_ECC_SOFT_BCH: + dev_info(&pdev->dev, "Using 4-bit SW BCH ECC scheme\n"); break; + default: - dev_warn(&pdev->dev, "No oob scheme defined for oobsize %d\n", - mtd->oobsize); - ret = -EINVAL; + dev_err(&pdev->dev, "Unsupported ECC mode!\n"); goto err_probe; } + + /* + * Don't set layout for BCH4 SW ECC. This will be + * generated later in nand_bch_init() later. + */ + if (nand->ecc.mode != NAND_ECC_SOFT_BCH) { + switch (host->mtd.oobsize) { + case 16: + nand->ecc.layout = &fsmc_ecc1_16_layout; + break; + case 64: + nand->ecc.layout = &fsmc_ecc1_64_layout; + break; + case 128: + nand->ecc.layout = &fsmc_ecc1_128_layout; + break; + default: + dev_warn(&pdev->dev, + "No oob scheme defined for oobsize %d\n", + mtd->oobsize); + ret = -EINVAL; + goto err_probe; + } + } } /* Second stage of scan to fill MTD data-structures */