[PATCH v2] mtd: gpmi: add sanity check for the ECC

Huang Shijie
2013-01-29T01:23:38Z

We do the check based on the following two facts:

[1] The mx23/mx28 can only support 20-bits ECC, while the mx6
can supports 40-bits ECC.

[2] The mx23/mx28 can only support the GF13, while the mx6
can supports GF13 and GF14.

Signed-off-by: Huang Shijie <b32955@freescale.com>
---
v1 --> v2:
[1] add the Golois Field check.
[2] change the comments.

---
drivers/mtd/nand/gpmi-nand/gpmi-nand.c | 28 ++++++++++++++++++++++++++--
drivers/mtd/nand/gpmi-nand/gpmi-nand.h | 4 ++++
2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
index 2521678..717881a 100644
--- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
+++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
@@ -94,6 +94,25 @@ static inline int get_ecc_strength(struct gpmi_nand_data *this)
return round_down(ecc_strength, 2);
}

+static inline bool gpmi_check_ecc(struct gpmi_nand_data *this)
+{
+ struct bch_geometry *geo = &this->bch_geometry;
+
+ /* Do the sanity check. */
+ if (GPMI_IS_MX23(this) || GPMI_IS_MX28(this)) {
+ /* The mx23/mx28 only support the GF13. */
+ if (geo->gf_len == 14)
+ return false;
+
+ if (geo->ecc_strength > MXS_ECC_STRENGTH_MAX)
+ return false;
+ } else if (GPMI_IS_MX6Q(this)) {
+ if (geo->ecc_strength > MX6_ECC_STRENGTH_MAX)
+ return false;
+ }
+ return true;
+}
+
int common_nfc_set_geometry(struct gpmi_nand_data *this)
{
struct bch_geometry *geo = &this->bch_geometry;
@@ -123,8 +142,13 @@ int common_nfc_set_geometry(struct gpmi_nand_data *this)

/* We use the same ECC strength for all chunks. */
geo->ecc_strength = get_ecc_strength(this);
- if (!geo->ecc_strength) {
- pr_err("wrong ECC strength.\n");
+ if (!gpmi_check_ecc(this)) {
+ dev_err(this->dev,
+ "We can not support this nand chip."
+ " Its required ecc strength(%d) is beyond our"
+ " capability(%d).\n", geo->ecc_strength,
+ (GPMI_IS_MX6Q(this) ? MX6_ECC_STRENGTH_MAX
+ : MXS_ECC_STRENGTH_MAX));
return -EINVAL;
}

diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.h b/drivers/mtd/nand/gpmi-nand/gpmi-nand.h
index 3d93a5e..0729477 100644
--- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.h
+++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.h
@@ -284,6 +284,10 @@ extern int gpmi_read_page(struct gpmi_nand_data *,
#define STATUS_ERASED 0xff
#define STATUS_UNCORRECTABLE 0xfe

+/* BCH's bit correction capability. */
+#define MXS_ECC_STRENGTH_MAX 20 /* mx23 and mx28 */
+#define MX6_ECC_STRENGTH_MAX 40
+
/* Use the platform_id to distinguish different Archs. */
#define IS_MX23 0x0
#define IS_MX28 0x1
--
1.7.0.4