[PATCH v2 02/14] mtd: spinand: Add enum spinand_proto to indicate current SPI IO mode

[Apurva Nandan <a-nandan@xxxxxx>]

Unlike Dual and Quad SPI modes flashes, Octal DTR SPI NAND flashes
require all instructions to be made in 8D-8D-8D protocol when the
flash is in Octal DTR mode. Hence, storing the current SPI IO mode
becomes necessary for correctly generating non-array access operations.

Store the current SPI IO mode in the spinand struct using a reg_proto
enum. This would act as a flag, denoting that the core should use
the given SPI protocol for non-page access operations.

Also provide basic macros for extracting buswidth and dtr mode
information from the spinand_proto enum.

Signed-off-by: Apurva Nandan <a-nandan@xxxxxx>
---
 drivers/mtd/nand/spi/core.c |  2 ++
 include/linux/mtd/spinand.h | 30 ++++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
index 2c8685f1f2fa..d82a3e6d9bb5 100644
--- a/drivers/mtd/nand/spi/core.c
+++ b/drivers/mtd/nand/spi/core.c
@@ -1155,6 +1155,7 @@ static void spinand_mtd_resume(struct mtd_info *mtd)
 	struct spinand_device *spinand = mtd_to_spinand(mtd);
 	int ret;
 
+	spinand->reg_proto = SPINAND_SINGLE_STR;
 	ret = spinand_reset_op(spinand);
 	if (ret)
 		return;
@@ -1181,6 +1182,7 @@ static int spinand_init(struct spinand_device *spinand)
 	if (!spinand->scratchbuf)
 		return -ENOMEM;
 
+	spinand->reg_proto = SPINAND_SINGLE_STR;
 	ret = spinand_detect(spinand);
 	if (ret)
 		goto err_free_bufs;
diff --git a/include/linux/mtd/spinand.h b/include/linux/mtd/spinand.h
index 6988956b8492..f6093cd98d7b 100644
--- a/include/linux/mtd/spinand.h
+++ b/include/linux/mtd/spinand.h
@@ -140,6 +140,31 @@
 		   SPI_MEM_OP_NO_DUMMY,					\
 		   SPI_MEM_OP_DATA_OUT(len, buf, 4))
 
+#define SPINAND_PROTO_BUSWIDTH_MASK	GENMASK(6, 0)
+#define SPINAND_PROTO_DTR_BIT		BIT(7)
+
+#define SPINAND_PROTO_STR(__buswidth)	\
+	((u8)(((__buswidth) - 1) & SPINAND_PROTO_BUSWIDTH_MASK))
+#define SPINAND_PROTO_DTR(__buswidth)	\
+	(SPINAND_PROTO_DTR_BIT | SPINAND_PROTO_STR(__buswidth))
+
+#define SPINAND_PROTO_BUSWIDTH(__proto)	\
+	((u8)(((__proto) & SPINAND_PROTO_BUSWIDTH_MASK) + 1))
+#define SPINAND_PROTO_IS_DTR(__proto)	(!!((__proto) & SPINAND_PROTO_DTR_BIT))
+
+/**
+ * enum spinand_proto - List allowable SPI protocol variants for read reg,
+ *			write reg, blk erase, write enable/disable, page read
+ *			and program exec operations.
+ */
+enum spinand_proto {
+	SPINAND_SINGLE_STR = SPINAND_PROTO_STR(1),
+	SPINAND_DUAL_STR = SPINAND_PROTO_STR(2),
+	SPINAND_QUAD_STR = SPINAND_PROTO_STR(4),
+	SPINAND_OCTAL_STR = SPINAND_PROTO_STR(8),
+	SPINAND_OCTAL_DTR = SPINAND_PROTO_DTR(8),
+};
+
 /**
  * Standard SPI NAND flash commands
  */
@@ -407,6 +432,9 @@ struct spinand_dirmap {
  *		   this die. Only required if your chip exposes several dies
  * @cur_target: currently selected target/die
  * @eccinfo: on-die ECC information
+ * @reg_proto: select a variant of SPI IO protocol (single, quad, octal or
+ *	       octal DTR) for read_reg/write_reg/erase operations. Update on
+ *	       successful transition into a different SPI IO protocol.
  * @cfg_cache: config register cache. One entry per die
  * @databuf: bounce buffer for data
  * @oobbuf: bounce buffer for OOB data
@@ -438,6 +466,8 @@ struct spinand_device {
 
 	struct spinand_ecc_info eccinfo;
 
+	enum spinand_proto reg_proto;
+
 	u8 *cfg_cache;
 	u8 *databuf;
 	u8 *oobbuf;
-- 
2.25.1