[PATCH 2/2] mtd: gpmi: add sanity check for the ECC strength

Huang Shijie
2013-01-25T06:04:08Z

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

Some new nand chips may require 40-bits ECC. So we should
add the sanity check for the ECC strength. If we can not
support this nand chip, we should quit.

Signed-off-by: Huang Shijie <b32955@freescale.com>
---
drivers/mtd/nand/gpmi-nand/gpmi-nand.c | 23 +++++++++++++++++++++--
drivers/mtd/nand/gpmi-nand/gpmi-nand.h | 4 ++++
2 files changed, 25 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..a19c42a 100644
--- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
+++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
@@ -94,6 +94,20 @@ static inline int get_ecc_strength(struct gpmi_nand_data *this)
return round_down(ecc_strength, 2);
}

+static inline bool check_ecc_strength(struct gpmi_nand_data *this,
+ int ecc_strength)
+{
+ /* Do the sanity check. */
+ if (GPMI_IS_MX23(this) || GPMI_IS_MX28(this)) {
+ if (ecc_strength > MXS_ECC_STRENGTH_MAX)
+ return false;
+ } else if (GPMI_IS_MX6Q(this)) {
+ if (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 +137,13 @@ 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 (!check_ecc_strength(this, geo->ecc_strength)) {
+ 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