[PATCH 5/5] MTD: at91: atmel_nand: for PMECC, add code to check the ONFI parameter ECC requirement.

Josh Wu
2013-01-23T12:47:12Z

This patch will check NAND flash's ecc minimum requirement in ONFI parameter.

1. if pmecc-cap, pmecc-sector-size is set in dts. then use it. Driver will
print out a WARNING if the values are different from ONFI parameters.
2. if pmecc-cap, pmecc-sector-size is not set in dts, then use the value
from ONFI parameters.
* If ONFI ECC parameters are in ONFI extended parameter page, since we are
not support it, so assume the minimum ecc requirement is 2 bits in 512
bytes.
* For non-ONFI support nand flash, also assume the minimum ecc requirement is
2 bits in 512 bytes.

Signed-off-by: Josh Wu <josh.wu@atmel.com>
---
drivers/mtd/nand/atmel_nand.c | 90 +++++++++++++++++++++++++++++++++++++++--
1 file changed, 87 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c
index f186a37..ffcbcca 100644
--- a/drivers/mtd/nand/atmel_nand.c
+++ b/drivers/mtd/nand/atmel_nand.c
@@ -910,6 +910,84 @@ static void atmel_pmecc_core_init(struct mtd_info *mtd)
pmecc_writel(host->ecc, CTRL, PMECC_CTRL_ENABLE);
}

+/*
+ * Get ECC requirement in ONFI parameters, returns -1 if ONFI
+ * parameters is not supported.
+ * return 0 if success to get the ECC requirement.
+ */
+static int get_onfi_ecc_param(struct nand_chip *chip,
+ int *ecc_bits, int *sector_size)
+{
+ *ecc_bits = *sector_size = 0;
+
+ if (chip->onfi_params.ecc_bits == 0xff)
+ /* TODO: the sector_size and ecc_bits need to be find in
+ * extended ecc parameter, currently we don't support it.
+ */
+ return -1;
+
+ *ecc_bits = chip->onfi_params.ecc_bits;
+
+ /* The default sector size (ecc codeword size) is 512 */
+ *sector_size = 512;
+
+ return 0;
+}
+
+/*
+ * Get ecc requirement from ONFI parameters ecc requirement.
+ * If pmecc-cap, pmecc-sector-size in DTS are not specified, this function
+ * will set them according to ONFI ecc requirement. Otherwise, use the
+ * value in DTS file.
+ * return 0 if success. otherwise return error code.
+ */
+static int pmecc_choose_ecc(struct atmel_nand_host *host,
+ int *cap, int *sector_size)
+{
+ /* Get ECC requirement from ONFI parameters */
+ *cap = *sector_size = 0;
+ if (host->nand_chip.onfi_version) {
+ if (!get_onfi_ecc_param(&host->nand_chip, cap, sector_size))
+ dev_info(host->dev, "ONFI params, minimum required ECC: %d bits in %d bytes\n",
+ *cap, *sector_size);
+ else
+ dev_info(host->dev, "NAND chip ECC reqirement is in Extended ONFI parameter, we don't support yet.\n");
+ } else {
+ dev_info(host->dev, "NAND chip is not ONFI compliant, assume ecc_bits is 2 in 512 bytes");
+ }
+ if (*cap == 0 && *sector_size == 0) {
+ *cap = 2;
+ *sector_size = 512;
+ }
+
+ /* If dts file doesn't specify then use the one in ONFI parameters */
+ if (host->pmecc_corr_cap == 0) {
+ /* use the most fitable ecc bits (the near bigger one ) */
+ if (*cap <= 2)
+ host->pmecc_corr_cap = 2;
+ else if (*cap <= 4)
+ host->pmecc_corr_cap = 4;
+ else if (*cap < 8)
+ host->pmecc_corr_cap = 8;
+ else if (*cap < 12)
+ host->pmecc_corr_cap = 12;
+ else if (*cap < 24)
+ host->pmecc_corr_cap = 24;
+ else
+ return -EINVAL;
+ }
+ if (host->pmecc_sector_size == 0) {
+ /* use the most fitable sector size (the near smaller one ) */
+ if (*sector_size >= 1024)
+ host->pmecc_sector_size = 1024;
+ else if (*sector_size >= 512)
+ host->pmecc_sector_size = 512;
+ else
+ return -EINVAL;
+ }
+ return 0;
+}
+
static int __init atmel_pmecc_nand_init_params(struct platform_device *pdev,
struct atmel_nand_host *host)
{
@@ -918,9 +996,15 @@ static int __init atmel_pmecc_nand_init_params(struct platform_device *pdev,
struct resource *regs, *regs_pmerr, *regs_rom;
int cap, sector_size, err_no;

- if (host->pmecc_corr_cap == 0 || host->pmecc_sector_size == 0)
- /* TODO: Should use ONFI ecc parameters. */
- return -EINVAL;
+ err_no = pmecc_choose_ecc(host, &cap, &sector_size);
+ if (err_no) {
+ dev_err(host->dev, "The NAND flash's ECC requirement are not support!");
+ return err_no;
+ }
+
+ if (cap != host->pmecc_corr_cap ||
+ sector_size != host->pmecc_sector_size)
+ dev_info(host->dev, "WARNING: Be Caution! Using different PMECC parameters from Nand ONFI ECC reqirement.\n");

cap = host->pmecc_corr_cap;
sector_size = host->pmecc_sector_size;
--
1.7.9.5