[PATCH 3/5] mtd: nand: gpmi: correct bitflip for erased NAND page

[Han Xu]

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@xxxxxxx>
---
 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 | 24 +++++++++++++++++++++++-
 drivers/mtd/nand/gpmi-nand/gpmi-nand.h |  5 ++++-
 4 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nand/gpmi-nand/bch-regs.h b/drivers/mtd/nand/gpmi-nand/bch-regs.h
index 53e58bc..a84d72b 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 8acbe04..2c43213 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 1aba6e6..6b3ca3b 100644
--- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
+++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
@@ -71,6 +71,12 @@ static const struct gpmi_devdata gpmi_devdata_imx6q = {
 	.max_chain_delay = 12,
 };
 
+static const struct gpmi_devdata gpmi_devdata_imx6qp = {
+	.type = IS_MX6QP,
+	.bch_max_ecc_strength = 40,
+	.max_chain_delay = 12,
+};
+
 static const struct gpmi_devdata gpmi_devdata_imx6sx = {
 	.type = IS_MX6SX,
 	.bch_max_ecc_strength = 62,
@@ -1010,6 +1016,7 @@ 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;
@@ -1018,6 +1025,7 @@ 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 flag = 0;
 
 	dev_dbg(this->dev, "page number is : %d\n", page);
 	ret = read_page_prepare(this, buf, nfc_geo->payload_size,
@@ -1050,9 +1058,16 @@ static int gpmi_ecc_read_page(struct mtd_info *mtd, struct nand_chip *chip,
 	status = auxiliary_virt + nfc_geo->auxiliary_status_offset;
 
 	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))
+				if (readl(bch_regs + HW_BCH_DEBUG1))
+					flag = 1;
+			continue;
+		}
+
 		if (*status == STATUS_UNCORRECTABLE) {
 			mtd->ecc_stats.failed++;
 			continue;
@@ -1081,6 +1096,10 @@ static int gpmi_ecc_read_page(struct mtd_info *mtd, struct nand_chip *chip,
 			nfc_geo->payload_size,
 			payload_virt, payload_phys);
 
+	/* if bitflip occurred in erased page, change data to all 0xff */
+	if (flag)
+		memset(buf, 0xff, nfc_geo->payload_size);
+
 	return max_bitflips;
 }
 
@@ -1988,6 +2007,9 @@ static const struct of_device_id gpmi_nand_id_table[] = {
 		.compatible = "fsl,imx6q-gpmi-nand",
 		.data = &gpmi_devdata_imx6q,
 	}, {
+		.compatible = "fsl,imx6qp-gpmi-nand",
+		.data = (void *)&gpmi_devdata_imx6qp,
+	}, {
 		.compatible = "fsl,imx6sx-gpmi-nand",
 		.data = &gpmi_devdata_imx6sx,
 	}, {
diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.h b/drivers/mtd/nand/gpmi-nand/gpmi-nand.h
index a82555f..605d96e 100644
--- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.h
+++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.h
@@ -123,6 +123,7 @@ enum gpmi_type {
 	IS_MX23,
 	IS_MX28,
 	IS_MX6Q,
+	IS_MX6QP,
 	IS_MX6SX,
 	IS_MX7D,
 };
@@ -305,9 +306,11 @@ void gpmi_copy_bits(u8 *dst, size_t dst_bit_off,
 #define GPMI_IS_MX23(x)		((x)->devdata->type == IS_MX23)
 #define GPMI_IS_MX28(x)		((x)->devdata->type == IS_MX28)
 #define GPMI_IS_MX6Q(x)		((x)->devdata->type == IS_MX6Q)
+#define GPMI_IS_MX6QP(x)	((x)->devdata->type == IS_MX6QP)
 #define GPMI_IS_MX6SX(x)	((x)->devdata->type == IS_MX6SX)
 #define GPMI_IS_MX7D(x)		((x)->devdata->type == IS_MX7D)
 
-#define GPMI_IS_MX6(x)		(GPMI_IS_MX6Q(x) || GPMI_IS_MX6SX(x))
+#define GPMI_IS_MX6(x)		(GPMI_IS_MX6Q(x) || GPMI_IS_MX6QP(x)\
+	   || GPMI_IS_MX6SX(x))
 #define GPMI_IS_MX7(x)		(GPMI_IS_MX7D(x))
 #endif
-- 
1.9.1