mtd: spi-nor: add support for DTR protocol

Double Transfer Rate (DTR) is SPI protocol in which data is transferred
on each clock edge as opposed to on each clock cycle. Make
framework-level changes to allow supporting flashes in DTR mode.

Right now, mixed DTR modes are not supported. So, for example a mode
like 4S-4D-4D will not work. All phases need to be either DTR or STR.

The xSPI spec says that "The program commands provide SPI backward
compatible commands for programming data...". So 8D-8D-8D page program
opcodes are populated with using 1S-1S-1S opcodes.
Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/20201005153138.6437-4-p.yadav@ti.com

drivers/mtd/spi-nor/core.h

@@ -62,6 +62,7 @@ enum spi_nor_read_command_index {
 	SNOR_CMD_READ_1_8_8,
 	SNOR_CMD_READ_8_8_8,
 	SNOR_CMD_READ_1_8_8_DTR,
+	SNOR_CMD_READ_8_8_8_DTR,
 
 	SNOR_CMD_READ_MAX
 };
@@ -78,6 +79,7 @@ enum spi_nor_pp_command_index {
 	SNOR_CMD_PP_1_1_8,
 	SNOR_CMD_PP_1_8_8,
 	SNOR_CMD_PP_8_8_8,
+	SNOR_CMD_PP_8_8_8_DTR,
 
 	SNOR_CMD_PP_MAX
 };
@@ -311,6 +313,8 @@ struct flash_info {
 					 * BP3 is bit 6 of status register.
 					 * Must be used with SPI_NOR_4BIT_BP.
 					 */
+#define SPI_NOR_OCTAL_DTR_READ	BIT(19) /* Flash supports octal DTR Read. */
+#define SPI_NOR_OCTAL_DTR_PP	BIT(20) /* Flash supports Octal DTR Page Program */
 
 	/* Part specific fixup hooks. */
 	const struct spi_nor_fixups *fixups;
@@ -399,6 +403,9 @@ extern const struct spi_nor_manufacturer spi_nor_winbond;
 extern const struct spi_nor_manufacturer spi_nor_xilinx;
 extern const struct spi_nor_manufacturer spi_nor_xmc;
 
+void spi_nor_spimem_setup_op(const struct spi_nor *nor,
+			     struct spi_mem_op *op,
+			     const enum spi_nor_protocol proto);
 int spi_nor_write_enable(struct spi_nor *nor);
 int spi_nor_write_disable(struct spi_nor *nor);
 int spi_nor_set_4byte_addr_mode(struct spi_nor *nor, bool enable);

drivers/mtd/spi-nor/sfdp.c

@@ -1047,9 +1047,16 @@ static int spi_nor_parse_4bait(struct spi_nor *nor,
 	}
 
 	/* 4BAIT is the only SFDP table that indicates page program support. */
-	if (pp_hwcaps & SNOR_HWCAPS_PP)
+	if (pp_hwcaps & SNOR_HWCAPS_PP) {
 		spi_nor_set_pp_settings(&params_pp[SNOR_CMD_PP],
 					SPINOR_OP_PP_4B, SNOR_PROTO_1_1_1);
+		/*
+		 * Since xSPI Page Program opcode is backward compatible with
+		 * Legacy SPI, use Legacy SPI opcode there as well.
+		 */
+		spi_nor_set_pp_settings(&params_pp[SNOR_CMD_PP_8_8_8_DTR],
+					SPINOR_OP_PP_4B, SNOR_PROTO_8_8_8_DTR);
+	}
 	if (pp_hwcaps & SNOR_HWCAPS_PP_1_1_4)
 		spi_nor_set_pp_settings(&params_pp[SNOR_CMD_PP_1_1_4],
 					SPINOR_OP_PP_1_1_4_4B,

include/linux/mtd/spi-nor.h

@@ -182,6 +182,7 @@ enum spi_nor_protocol {
 	SNOR_PROTO_1_2_2_DTR = SNOR_PROTO_DTR(1, 2, 2),
 	SNOR_PROTO_1_4_4_DTR = SNOR_PROTO_DTR(1, 4, 4),
 	SNOR_PROTO_1_8_8_DTR = SNOR_PROTO_DTR(1, 8, 8),
+	SNOR_PROTO_8_8_8_DTR = SNOR_PROTO_DTR(8, 8, 8),
 };
 
 static inline bool spi_nor_protocol_is_dtr(enum spi_nor_protocol proto)
@@ -228,7 +229,7 @@ struct spi_nor_hwcaps {
  * then Quad SPI protocols before Dual SPI protocols, Fast Read and lastly
  * (Slow) Read.
  */
-#define SNOR_HWCAPS_READ_MASK		GENMASK(14, 0)
+#define SNOR_HWCAPS_READ_MASK		GENMASK(15, 0)
 #define SNOR_HWCAPS_READ		BIT(0)
 #define SNOR_HWCAPS_READ_FAST		BIT(1)
 #define SNOR_HWCAPS_READ_1_1_1_DTR	BIT(2)
@@ -245,11 +246,12 @@ struct spi_nor_hwcaps {
 #define SNOR_HWCAPS_READ_4_4_4		BIT(9)
 #define SNOR_HWCAPS_READ_1_4_4_DTR	BIT(10)
 
-#define SNOR_HWCAPS_READ_OCTAL		GENMASK(14, 11)
+#define SNOR_HWCAPS_READ_OCTAL		GENMASK(15, 11)
 #define SNOR_HWCAPS_READ_1_1_8		BIT(11)
 #define SNOR_HWCAPS_READ_1_8_8		BIT(12)
 #define SNOR_HWCAPS_READ_8_8_8		BIT(13)
 #define SNOR_HWCAPS_READ_1_8_8_DTR	BIT(14)
+#define SNOR_HWCAPS_READ_8_8_8_DTR	BIT(15)
 
 /*
  * Page Program capabilities.
@@ -260,18 +262,19 @@ struct spi_nor_hwcaps {
  * JEDEC/SFDP standard to define them. Also at this moment no SPI flash memory
  * implements such commands.
  */
-#define SNOR_HWCAPS_PP_MASK	GENMASK(22, 16)
-#define SNOR_HWCAPS_PP		BIT(16)
+#define SNOR_HWCAPS_PP_MASK		GENMASK(23, 16)
+#define SNOR_HWCAPS_PP			BIT(16)
 
-#define SNOR_HWCAPS_PP_QUAD	GENMASK(19, 17)
-#define SNOR_HWCAPS_PP_1_1_4	BIT(17)
-#define SNOR_HWCAPS_PP_1_4_4	BIT(18)
-#define SNOR_HWCAPS_PP_4_4_4	BIT(19)
+#define SNOR_HWCAPS_PP_QUAD		GENMASK(19, 17)
+#define SNOR_HWCAPS_PP_1_1_4		BIT(17)
+#define SNOR_HWCAPS_PP_1_4_4		BIT(18)
+#define SNOR_HWCAPS_PP_4_4_4		BIT(19)
 
-#define SNOR_HWCAPS_PP_OCTAL	GENMASK(22, 20)
-#define SNOR_HWCAPS_PP_1_1_8	BIT(20)
-#define SNOR_HWCAPS_PP_1_8_8	BIT(21)
-#define SNOR_HWCAPS_PP_8_8_8	BIT(22)
+#define SNOR_HWCAPS_PP_OCTAL		GENMASK(23, 20)
+#define SNOR_HWCAPS_PP_1_1_8		BIT(20)
+#define SNOR_HWCAPS_PP_1_8_8		BIT(21)
+#define SNOR_HWCAPS_PP_8_8_8		BIT(22)
+#define SNOR_HWCAPS_PP_8_8_8_DTR	BIT(23)
 
 #define SNOR_HWCAPS_X_X_X	(SNOR_HWCAPS_READ_2_2_2 |	\
 				 SNOR_HWCAPS_READ_4_4_4 |	\
@@ -279,10 +282,14 @@ struct spi_nor_hwcaps {
 				 SNOR_HWCAPS_PP_4_4_4 |		\
 				 SNOR_HWCAPS_PP_8_8_8)
 
+#define SNOR_HWCAPS_X_X_X_DTR	(SNOR_HWCAPS_READ_8_8_8_DTR |	\
+				 SNOR_HWCAPS_PP_8_8_8_DTR)
+
 #define SNOR_HWCAPS_DTR		(SNOR_HWCAPS_READ_1_1_1_DTR |	\
 				 SNOR_HWCAPS_READ_1_2_2_DTR |	\
 				 SNOR_HWCAPS_READ_1_4_4_DTR |	\
-				 SNOR_HWCAPS_READ_1_8_8_DTR)
+				 SNOR_HWCAPS_READ_1_8_8_DTR |	\
+				 SNOR_HWCAPS_READ_8_8_8_DTR)
 
 #define SNOR_HWCAPS_ALL		(SNOR_HWCAPS_READ_MASK |	\
 				 SNOR_HWCAPS_PP_MASK)
@@ -318,6 +325,22 @@ struct spi_nor_controller_ops {
 	int (*erase)(struct spi_nor *nor, loff_t offs);
 };
 
+/**
+ * enum spi_nor_cmd_ext - describes the command opcode extension in DTR mode
+ * @SPI_NOR_EXT_NONE: no extension. This is the default, and is used in Legacy
+ *		      SPI mode
+ * @SPI_NOR_EXT_REPEAT: the extension is same as the opcode
+ * @SPI_NOR_EXT_INVERT: the extension is the bitwise inverse of the opcode
+ * @SPI_NOR_EXT_HEX: the extension is any hex value. The command and opcode
+ *		     combine to form a 16-bit opcode.
+ */
+enum spi_nor_cmd_ext {
+	SPI_NOR_EXT_NONE = 0,
+	SPI_NOR_EXT_REPEAT,
+	SPI_NOR_EXT_INVERT,
+	SPI_NOR_EXT_HEX,
+};
+
 /*
  * Forward declarations that are used internally by the core and manufacturer
  * drivers.
@@ -345,6 +368,7 @@ struct spi_nor_flash_parameter;
  * @program_opcode:	the program opcode
  * @sst_write_second:	used by the SST write operation
  * @flags:		flag options for the current SPI NOR (SNOR_F_*)
+ * @cmd_ext_type:	the command opcode extension type for DTR mode.
  * @read_proto:		the SPI protocol for read operations
  * @write_proto:	the SPI protocol for write operations
  * @reg_proto:		the SPI protocol for read_reg/write_reg/erase operations
@@ -376,6 +400,7 @@ struct spi_nor {
 	enum spi_nor_protocol	reg_proto;
 	bool			sst_write_second;
 	u32			flags;
+	enum spi_nor_cmd_ext	cmd_ext_type;
 
 	const struct spi_nor_controller_ops *controller_ops;