mtd: spi-nor: parse Serial Flash Discoverable Parameters (SFDP) tables

This patch adds support to the JESD216 rev B standard and parses the SFDP
tables to dynamically initialize the 'struct spi_nor_flash_parameter'.
Signed-off-by: Cyrille Pitchen <cyrille.pitchen@microchip.com>
Reviewed-by: Marek Vasut <marek.vasut@gmail.com>

include/linux/mtd/spi-nor.h

@@ -41,6 +41,8 @@
 #define SPINOR_OP_WREN		0x06	/* Write enable */
 #define SPINOR_OP_RDSR		0x05	/* Read status register */
 #define SPINOR_OP_WRSR		0x01	/* Write status register 1 byte */
+#define SPINOR_OP_RDSR2		0x3f	/* Read status register 2 */
+#define SPINOR_OP_WRSR2		0x3e	/* Write status register 2 */
 #define SPINOR_OP_READ		0x03	/* Read data bytes (low frequency) */
 #define SPINOR_OP_READ_FAST	0x0b	/* Read data bytes (high frequency) */
 #define SPINOR_OP_READ_1_1_2	0x3b	/* Read data bytes (Dual Output SPI) */
@@ -56,6 +58,7 @@
 #define SPINOR_OP_CHIP_ERASE	0xc7	/* Erase whole flash chip */
 #define SPINOR_OP_SE		0xd8	/* Sector erase (usually 64KiB) */
 #define SPINOR_OP_RDID		0x9f	/* Read JEDEC ID */
+#define SPINOR_OP_RDSFDP	0x5a	/* Read SFDP */
 #define SPINOR_OP_RDCR		0x35	/* Read configuration register */
 #define SPINOR_OP_RDFSR		0x70	/* Read flag status register */
 
@@ -128,6 +131,9 @@
 /* Configuration Register bits. */
 #define CR_QUAD_EN_SPAN		BIT(1)	/* Spansion Quad I/O */
 
+/* Status Register 2 bits. */
+#define SR2_QUAD_EN_BIT7	BIT(7)
+
 /* Supported SPI protocols */
 #define SNOR_PROTO_INST_MASK	GENMASK(23, 16)
 #define SNOR_PROTO_INST_SHIFT	16