mtd: gpmi: add sanity check for the ECC

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>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

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 25216785f180..717881a3d1b8 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 3d93a5e39090..072947731277 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