Another problem of this driver is hard-coded ecc.strength and
ecc.bytes. Currently ecc.bytes is defined as follows:
#define ECC_8BITS 14
#define ECC_15BITS 26
Such parameters were hard-coded because only the following two cases
are possible on Intel platforms:
- ecc.size = 512, ecc.strength = 8 --> ecc.bytes = 14
- ecc.size = 512, ecc.strength = 15 --> ecc.bytes = 26
However, these are actually customizable parameters, for example,
UniPhier platform supports the following:
- ecc.size = 1024, ecc.strength = 8 --> ecc.bytes = 14
- ecc.size = 1024, ecc.strength = 16 --> ecc.bytes = 28
- ecc.size = 1024, ecc.strength = 24 --> ecc.bytes = 42
So, we need somehow a generic way to calculate these parameters.
Fortunately, the Denali User's Guide explains how to calculate the
ecc.bytes. The formula is:
ecc.bytes = 2 * CEIL(13 * ecc.strength / 16) (for ecc.size = 512)
ecc.bytes = 2 * CEIL(14 * ecc.strength / 16) (for ecc.size = 1024)
This commit implements two functions denali_calc_ecc_bytes() and
denali_set_max_ecc_strength() to prepare for the next commit,
where I will allow to use SoC-dependent ecc.strength values.
Signed-off-by: Masahiro Yamada <yamada.masah...@socionext.com>
---
drivers/mtd/nand/denali.c | 72 +++++++++++++++++++++++++++++------------------
1 file changed, 45 insertions(+), 27 deletions(-)
diff --git a/drivers/mtd/nand/denali.c b/drivers/mtd/nand/denali.c
index c17e92b..f2ed3f8 100644
--- a/drivers/mtd/nand/denali.c
+++ b/drivers/mtd/nand/denali.c
@@ -1354,13 +1354,44 @@ static void denali_hw_init(struct denali_nand_info
*denali)
denali_irq_init(denali);
}
-/*
- * Althogh controller spec said SLC ECC is forceb to be 4bit,
- * but denali controller in MRST only support 15bit and 8bit ECC
- * correction
- */
-#define ECC_8BITS 14
-#define ECC_15BITS 26
+/* default of supported ECC strength for Intel platforms. */
+static const int denali_default_ecc_strength[] = {
+ 15, 8, 0,
+};
+
+static int denali_calc_ecc_bytes(int ecc_size, int ecc_strength)
+{
+ WARN_ON(ecc_size != 512 && ecc_size != 1024);
+
+ return DIV_ROUND_UP(ecc_strength * (ecc_size == 512 ? 13 : 14), 16) * 2;
+}
+
+static int denali_set_max_ecc_strength(struct denali_nand_info *denali)
+{
+ struct nand_chip *chip = &denali->nand;
+ struct mtd_info *mtd = nand_to_mtd(chip);
+ int oobsize = mtd->oobsize;
+ int ecc_size = chip->ecc.size;
+ int ecc_steps = mtd->writesize / chip->ecc.size;
+ const int *ecc_strength = denali_default_ecc_strength;
+ int ecc_bytes;
+
+ /* carve out the BBM area */
+ oobsize -= denali->bbtskipbytes;
+
+ for (; *ecc_strength; ecc_strength++) {
+ ecc_bytes = denali_calc_ecc_bytes(ecc_size, *ecc_strength);
+ if (oobsize >= ecc_bytes * ecc_steps) {
+ chip->ecc.strength = *ecc_strength;
+ return 0;
+ }
+ }
+
+ dev_err(denali->dev,
+ "Your NAND chip OOB is too small. No available ECC
strength.\n");
+
+ return -EINVAL;
+}
static int denali_ooblayout_ecc(struct mtd_info *mtd, int section,
struct mtd_oob_region *oobregion)
@@ -1594,27 +1625,14 @@ int denali_init(struct denali_nand_info *denali)
chip->ecc.size = denali->caps & DENALI_CAPS_ECC_SIZE_1024 ?
1024 : 512;
- /*
- * Denali Controller only support 15bit and 8bit ECC in MRST,
- * so just let controller do 15bit ECC for MLC and 8bit ECC for
- * SLC if possible.
- * */
- if (!nand_is_slc(chip) &&
- mtd->oobsize >= denali->bbtskipbytes +
- ECC_15BITS * (mtd->writesize / chip->ecc.size)) {
- /* if MLC OOB size is large enough, use 15bit ECC*/
- chip->ecc.strength = 15;
- chip->ecc.bytes = ECC_15BITS;
- iowrite32(15, denali->flash_reg + ECC_CORRECTION);
- } else if (mtd->oobsize <
- denali->bbtskipbytes + ECC_8BITS * (mtd->writesize /
chip->ecc.size)) {
- pr_err("Your NAND chip OOB is not large enough to contain 8bit
ECC correction codes");
+ ret = denali_set_max_ecc_strength(denali);
+ if (ret)
goto failed_req_irq;
- } else {
- chip->ecc.strength = 8;
- chip->ecc.bytes = ECC_8BITS;
- iowrite32(8, denali->flash_reg + ECC_CORRECTION);
- }
+
+ chip->ecc.bytes = denali_calc_ecc_bytes(chip->ecc.size,
+ chip->ecc.strength);
+
+ iowrite32(chip->ecc.strength, denali->flash_reg + ECC_CORRECTION);
mtd_set_ooblayout(mtd, &denali_ooblayout_ops);
--
2.7.4
