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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 <sr@denx.de>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
[Brian: tweaked the comments a bit]
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
This commit is contained in:
Stefan Roese 2015-10-19 08:40:13 +02:00 committed by Brian Norris
parent 48c25cf441
commit e278fc71b2
2 changed files with 47 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
Documentation/devicetree/bindings/mtd/fsmc-nand.txt
View File

@ -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:

57
drivers/mtd/nand/fsmc_nand.c
View File

@ -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 */