mtd: spi-nor: add support for Macronix Octal flash

Follow patch <f6adec1af4b2f5d3012480c6cdce7743b74a6156> (Allow using Micron mt35xu512aba
in Octal DTR mode).
Enable Octal DTR mode with 20 dummy cycles to allow running at the
maximum supported frequency for adding Macronix flash in Octal DTR mode.
 -https://www.mxic.com.tw/Lists/Datasheet/Attachments/7841/MX25LM51245G,%203V,%20512Mb,%20v1.1.pdf

Signed-off-by: JaimeLiao <jaimeliao.tw@gmail.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index 4ceeae6..c76235d 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -119,6 +119,16 @@
 /* Used for Macronix and Winbond flashes. */
 #define SPINOR_OP_EN4B		0xb7	/* Enter 4-byte mode */
 #define SPINOR_OP_EX4B		0xe9	/* Exit 4-byte mode */
+#define SPINOR_OP_EN4B			0xb7		/* Enter 4-byte mode */
+#define SPINOR_OP_EX4B			0xe9		/* Exit 4-byte mode */
+#define SPINOR_OP_RD_CR2		0x71		/* Read configuration register 2 */
+#define SPINOR_OP_WR_CR2		0x72		/* Write configuration register 2 */
+#define SPINOR_OP_MXIC_DTR_RD		0xee		/* Fast Read opcode in DTR mode */
+#define SPINOR_REG_MXIC_CR2_MODE	0x00000000	/* For setting octal DTR mode */
+#define SPINOR_REG_MXIC_OPI_DTR_EN	0x2		/* Enable Octal DTR */
+#define SPINOR_REG_MXIC_CR2_DC		0x00000300	/* For setting dummy cycles */
+#define SPINOR_REG_MXIC_DC_20		0x0		/* Setting dummy cycles to 20 */
+#define MXIC_MAX_DC			20		/* Maximum value of dummy cycles */
 
 /* Used for Spansion flashes only. */
 #define SPINOR_OP_BRWR		0x17	/* Bank register write */