mtd: spi-nor: Enable QE bit for ISSI flash

Enable QE bit for ISSI flash chips.

QE enablement logic is similar to what Macronix
has, so reuse the existing code itself.

Cc: Sagar Shrikant Kadam <sagar.kadam@sifive.com>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c
index 3bf8ddf..e840c60 100644
--- a/drivers/mtd/spi/spi-nor-core.c
+++ b/drivers/mtd/spi/spi-nor-core.c
@@ -325,6 +325,7 @@
 	case SNOR_MFR_MICRON:
 		/* Some Micron need WREN command; all will accept it */
 		need_wren = true;
+	case SNOR_MFR_ISSI:
 	case SNOR_MFR_MACRONIX:
 	case SNOR_MFR_WINBOND:
 		if (need_wren)
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index ec144a0..233fdc3 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -22,6 +22,7 @@
 #define SNOR_MFR_INTEL		CFI_MFR_INTEL
 #define SNOR_MFR_ST		CFI_MFR_ST /* ST Micro <--> Micron */
 #define SNOR_MFR_MICRON		CFI_MFR_MICRON /* ST Micro <--> Micron */
+#define SNOR_MFR_ISSI		CFI_MFR_PMC
 #define SNOR_MFR_MACRONIX	CFI_MFR_MACRONIX
 #define SNOR_MFR_SPANSION	CFI_MFR_AMD
 #define SNOR_MFR_SST		CFI_MFR_SST