[PATCH v2 4/6] mtd: nand: gpmi: correct bitflip for erased NAND page

Han Xu
2016-06-10T17:00:33Z

i.MX6QP and i.MX7D BCH module integrated a new feature to detect the
bitflip number for erased NAND page. So for these two platform, set the
erase threshold to ecc_strength and if bitflip detected, GPMI driver
will correct the data to all 0xFF.

Signed-off-by: Han Xu <han.xu@nxp.com>
---
drivers/mtd/nand/gpmi-nand/bch-regs.h | 10 ++++++++++
drivers/mtd/nand/gpmi-nand/gpmi-lib.c | 5 +++++
drivers/mtd/nand/gpmi-nand/gpmi-nand.c | 27 ++++++++++++++++++++++++++-
3 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/nand/gpmi-nand/bch-regs.h b/drivers/mtd/nand/gpmi-nand/bch-regs.h
index 228142c..2c44b88 100644
--- a/drivers/mtd/nand/gpmi-nand/bch-regs.h
+++ b/drivers/mtd/nand/gpmi-nand/bch-regs.h
@@ -30,7 +30,13 @@
#define BM_BCH_CTRL_COMPLETE_IRQ (1 << 0)

#define HW_BCH_STATUS0 0x00000010
+
#define HW_BCH_MODE 0x00000020
+#define BP_BCH_MODE_ERASE_THRESHOLD 0
+#define BM_BCH_MODE_ERASE_THRESHOLD (0xff << BP_BCH_MODE_ERASE_THRESHOLD)
+#define BF_BCH_MODE_ERASE_THRESHOLD(v) \
+ (((v) << BP_BCH_MODE_ERASE_THRESHOLD) & BM_BCH_MODE_ERASE_THRESHOLD)
+
#define HW_BCH_ENCODEPTR 0x00000030
#define HW_BCH_DATAPTR 0x00000040
#define HW_BCH_METAPTR 0x00000050
@@ -125,4 +131,8 @@
)

#define HW_BCH_VERSION 0x00000160
+#define HW_BCH_DEBUG1 0x00000170
+#define BP_BCH_DEBUG1_ERASED_ZERO_COUNT 0
+#define BM_BCH_DEBUG1_ERASED_ZERO_COUNT \
+ (0x1ff << BP_BCH_DEBUG1_ERASED_ZERO_COUNT)
#endif
diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-lib.c b/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
index 358ff5d..0b5666a 100644
--- a/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
+++ b/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
@@ -298,6 +298,11 @@ int bch_set_geometry(struct gpmi_nand_data *this)
| BF_BCH_FLASH0LAYOUT1_DATAN_SIZE(block_size, this),
r->bch_regs + HW_BCH_FLASH0LAYOUT1);

+ /* Set erase threshold to ecc_strength for mx6qp and mx7 */
+ if (GPMI_IS_MX6QP(this) || GPMI_IS_MX7(this))
+ writel(BF_BCH_MODE_ERASE_THRESHOLD(ecc_strength),
+ r->bch_regs + HW_BCH_MODE);
+
/* Set *all* chip selects to use layout 0. */
writel(0, r->bch_regs + HW_BCH_LAYOUTSELECT);

diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
index aedaff3..03bdb4d 100644
--- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
+++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
@@ -1043,6 +1043,7 @@ static int gpmi_ecc_read_page(struct mtd_info *mtd, struct nand_chip *chip,
{
struct gpmi_nand_data *this = nand_get_controller_data(chip);
struct bch_geometry *nfc_geo = &this->bch_geometry;
+ void __iomem *bch_regs = this->resources.bch_regs;
void *payload_virt;
dma_addr_t payload_phys;
void *auxiliary_virt;
@@ -1051,6 +1052,8 @@ static int gpmi_ecc_read_page(struct mtd_info *mtd, struct nand_chip *chip,
unsigned char *status;
unsigned int max_bitflips = 0;
int ret;
+ int bitflips = 0;
+ int bitflip_flag = 0;

dev_dbg(this->dev, "page number is : %d\n", page);
ret = read_page_prepare(this, buf, nfc_geo->payload_size,
@@ -1088,8 +1091,20 @@ static int gpmi_ecc_read_page(struct mtd_info *mtd, struct nand_chip *chip,
payload_virt, payload_phys);

for (i = 0; i < nfc_geo->ecc_chunk_count; i++, status++) {
- if ((*status == STATUS_GOOD) || (*status == STATUS_ERASED))
+ if (*status == STATUS_GOOD)
+ continue;
+ if (*status == STATUS_ERASED) {
+ if (GPMI_IS_MX6QP(this) || GPMI_IS_MX7(this)) {
+ bitflips = readl(bch_regs + HW_BCH_DEBUG1);
+ if (bitflips) {
+ bitflip_flag = 1;
+ max_bitflips = max_t(unsigned int,
+ max_bitflips,
+ bitflips);
+ }
+ }
continue;
+ }

if (*status == STATUS_UNCORRECTABLE) {
int eccbits = nfc_geo->ecc_strength * nfc_geo->gf_len;
@@ -1098,6 +1113,10 @@ static int gpmi_ecc_read_page(struct mtd_info *mtd, struct nand_chip *chip,
int eccbytes;
int flips;

+ /* shortcut for i.MX7 and i.MX6QP */
+ if (GPMI_IS_MX6QP(this) || GPMI_IS_MX7(this))
+ continue;
+
/* Read ECC bytes into our internal raw_buffer */
offset = nfc_geo->metadata_size * 8;
offset += ((8 * nfc_geo->ecc_chunk_size) + eccbits) * (i + 1);
@@ -1182,6 +1201,12 @@ static int gpmi_ecc_read_page(struct mtd_info *mtd, struct nand_chip *chip,
chip->oob_poi[0] = ((uint8_t *) auxiliary_virt)[0];
}

+ /* if bitflip occurred in erased page, change data to all 0xff */
+ if (bitflip_flag) {
+ memset(buf, ~0, nfc_geo->payload_size);
+ memset(chip->oob_poi, ~0, mtd->oobsize);
+ }
+
return max_bitflips;
}

--
1.9.1