[PATCH] mtd: spinand: fmsh: add support for FM25G01B and FM25G02B

Add the FudanMicro FM25G01B (1Gbit) and FM25G02B (2Gbit) SPI-NAND
parts. Both have 2048-byte pages with 128 bytes of spare area, 64
pages per erase block, and on-die ECC with a strength of 8 bits per
528-byte step. Their ECC status field is 3 bits wide and reports each
bitflip count from four to eight separately, so it needs a decoder of
its own instead of the coarse ranges the other parts in this file use.

The 0xEB Quad I/O read-from-cache operation takes a single dummy byte
on these chips rather than the two the shared read_cache_variants set
uses, hence the separate variant set: with the extra dummy byte the
data phase is shifted and reads return corrupted data without any ECC
error being reported.

FM25G01B datasheet: https://www.fmsh.com/nvm/FM25G01B_ds_eng.pdf
FM25G02B datasheet: https://www.fmsh.com/nvm/FM25G02B_ds_eng.pdf

This is a port of linux commits
d5a5c9eb2ee9 ("mtd: spinand: fmsh: add support for FM25G{01,02}B")
8211f2d74b35 ("mtd: spinand: fmsh: fix FM25G01B/FM25G02B Quad I/O read
dummy cycles")
which are queued in the MTD tree and not in mainline yet.

Tested on a Keenetic KN-1012 (MT7981B) that boots from an FM25G02B.
FM25G01B is taken over from the Linux table and is untested here.

Signed-off-by: Aleksei Sviridkin <[email protected]>
---
 drivers/mtd/nand/spi/fmsh.c | 103 ++++++++++++++++++++++++++++++++++++
 1 file changed, 103 insertions(+)

diff --git a/drivers/mtd/nand/spi/fmsh.c b/drivers/mtd/nand/spi/fmsh.c
index 80837b7dd..dc6c3fc35 100644
--- a/drivers/mtd/nand/spi/fmsh.c
+++ b/drivers/mtd/nand/spi/fmsh.c
@@ -11,6 +11,16 @@
 #endif
 #include <linux/mtd/spinand.h>
 
+#define FM25G01B_STATUS_ECC_MASK		(7 << 4)
+	#define FM25G01B_STATUS_ECC_NO_BITFLIPS		(0 << 4)
+	#define FM25G01B_STATUS_ECC_1_3_BITFLIPS	(1 << 4)
+	#define FM25G01B_STATUS_ECC_4_BITFLIPS		(2 << 4)
+	#define FM25G01B_STATUS_ECC_5_BITFLIPS		(3 << 4)
+	#define FM25G01B_STATUS_ECC_6_BITFLIPS		(4 << 4)
+	#define FM25G01B_STATUS_ECC_7_BITFLIPS		(5 << 4)
+	#define FM25G01B_STATUS_ECC_8_BITFLIPS		(6 << 4)
+	#define FM25G01B_STATUS_ECC_UNCOR_ERROR		(7 << 4)
+
 #define SPINAND_MFR_FMSH		0xA1
 
 static SPINAND_OP_VARIANTS(read_cache_variants,
@@ -29,6 +39,74 @@ static SPINAND_OP_VARIANTS(update_cache_variants,
 		SPINAND_PROG_LOAD_1S_1S_4S_OP(false, 0, NULL, 0),
 		SPINAND_PROG_LOAD_1S_1S_1S_OP(false, 0, NULL, 0));
 
+static SPINAND_OP_VARIANTS(fm25g_read_cache_variants,
+		SPINAND_PAGE_READ_FROM_CACHE_1S_4S_4S_OP(0, 1, NULL, 0, 0),
+		SPINAND_PAGE_READ_FROM_CACHE_1S_1S_4S_OP(0, 1, NULL, 0, 0),
+		SPINAND_PAGE_READ_FROM_CACHE_1S_2S_2S_OP(0, 1, NULL, 0, 0),
+		SPINAND_PAGE_READ_FROM_CACHE_1S_1S_2S_OP(0, 1, NULL, 0, 0),
+		SPINAND_PAGE_READ_FROM_CACHE_FAST_1S_1S_1S_OP(0, 1, NULL, 0, 0),
+		SPINAND_PAGE_READ_FROM_CACHE_1S_1S_1S_OP(0, 1, NULL, 0, 0));
+
+static int fm25g01b_ooblayout_ecc(struct mtd_info *mtd, int section,
+				  struct mtd_oob_region *region)
+{
+	if (section)
+		return -ERANGE;
+
+	region->offset = 64;
+	region->length = 64;
+
+	return 0;
+}
+
+static int fm25g01b_ooblayout_free(struct mtd_info *mtd, int section,
+				   struct mtd_oob_region *region)
+{
+	if (section)
+		return -ERANGE;
+
+	/* reserve 2 bytes for the BBM */
+	region->offset = 2;
+	region->length = 62;
+
+	return 0;
+}
+
+static int fm25g01b_ecc_get_status(struct spinand_device *spinand,
+				   u8 status)
+{
+	switch (status & FM25G01B_STATUS_ECC_MASK) {
+	case FM25G01B_STATUS_ECC_NO_BITFLIPS:
+		return 0;
+
+	case FM25G01B_STATUS_ECC_1_3_BITFLIPS:
+		return 3;
+
+	case FM25G01B_STATUS_ECC_4_BITFLIPS:
+		return 4;
+
+	case FM25G01B_STATUS_ECC_5_BITFLIPS:
+		return 5;
+
+	case FM25G01B_STATUS_ECC_6_BITFLIPS:
+		return 6;
+
+	case FM25G01B_STATUS_ECC_7_BITFLIPS:
+		return 7;
+
+	case FM25G01B_STATUS_ECC_8_BITFLIPS:
+		return 8;
+
+	case FM25G01B_STATUS_ECC_UNCOR_ERROR:
+		return -EBADMSG;
+
+	default:
+		break;
+	}
+
+	return -EINVAL;
+}
+
 static int fm25s01a_ooblayout_ecc(struct mtd_info *mtd, int section,
 				  struct mtd_oob_region *region)
 {
@@ -47,12 +125,37 @@ static int fm25s01a_ooblayout_free(struct mtd_info *mtd, int section,
 	return 0;
 }
 
+static const struct mtd_ooblayout_ops fm25g01b_ooblayout = {
+	.ecc = fm25g01b_ooblayout_ecc,
+	.rfree = fm25g01b_ooblayout_free,
+};
+
 static const struct mtd_ooblayout_ops fm25s01a_ooblayout = {
 	.ecc = fm25s01a_ooblayout_ecc,
 	.rfree = fm25s01a_ooblayout_free,
 };
 
 static const struct spinand_info fmsh_spinand_table[] = {
+	SPINAND_INFO("FM25G01B",
+		     SPINAND_ID(SPINAND_READID_METHOD_OPCODE_DUMMY, 0xd1),
+		     NAND_MEMORG(1, 2048, 128, 64, 1024, 21, 1, 1, 1),
+		     NAND_ECCREQ(8, 528),
+		     SPINAND_INFO_OP_VARIANTS(&fm25g_read_cache_variants,
+					      &write_cache_variants,
+					      &update_cache_variants),
+		     SPINAND_HAS_QE_BIT,
+		     SPINAND_ECCINFO(&fm25g01b_ooblayout,
+				     fm25g01b_ecc_get_status)),
+	SPINAND_INFO("FM25G02B",
+		     SPINAND_ID(SPINAND_READID_METHOD_OPCODE_DUMMY, 0xd2),
+		     NAND_MEMORG(1, 2048, 128, 64, 2048, 41, 1, 1, 1),
+		     NAND_ECCREQ(8, 528),
+		     SPINAND_INFO_OP_VARIANTS(&fm25g_read_cache_variants,
+					      &write_cache_variants,
+					      &update_cache_variants),
+		     SPINAND_HAS_QE_BIT,
+		     SPINAND_ECCINFO(&fm25g01b_ooblayout,
+				     fm25g01b_ecc_get_status)),
 	SPINAND_INFO("FM25S01A",
 		     SPINAND_ID(SPINAND_READID_METHOD_OPCODE_DUMMY, 0xE4),
 		     NAND_MEMORG(1, 2048, 64, 64, 1024, 20, 1, 1, 1),
-- 
2.55.0