This patch adds Global block protection unlock support for SST flash parts

Signed-off-by: Anurag Kumar Vulisha <[email protected]>
---
 drivers/mtd/spi-nor/spi-nor.c | 8 ++++++++
 include/linux/mtd/spi-nor.h   | 1 +
 2 files changed, 9 insertions(+)

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index 4988390..787ab95 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -68,6 +68,8 @@ struct flash_info {
 #define        SPI_NOR_DUAL_READ       0x20    /* Flash supports Dual Read */
 #define        SPI_NOR_QUAD_READ       0x40    /* Flash supports Quad Read */
 #define        USE_FSR                 0x80    /* use flag status register */
+/* Unlock the Global protection for sst flashes */
+#define        SST_GLOBAL_PROT_UNLK    0x100
 };
 
 #define JEDEC_MFR(info)        ((info)->id[0])
@@ -1204,6 +1206,12 @@ int spi_nor_scan(struct spi_nor *nor, const char *name, 
enum read_mode mode)
            JEDEC_MFR(info) == SNOR_MFR_WINBOND) {
                write_enable(nor);
                write_sr(nor, 0);
+
+               if (info->flags & SST_GLOBAL_PROT_UNLK) {
+                       write_enable(nor);
+                       /* Unlock global write protection bits */
+                       nor->write_reg(nor, GLOBAL_BLKPROT_UNLK, NULL, 0);
+               }
        }
 
        if (!mtd->name)
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index c8723b6..37e1abf 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -65,6 +65,7 @@
 #define SPINOR_OP_BP           0x02    /* Byte program */
 #define SPINOR_OP_WRDI         0x04    /* Write disable */
 #define SPINOR_OP_AAI_WP       0xad    /* Auto address increment word program 
*/
+#define GLOBAL_BLKPROT_UNLK    0x98    /* Clear global write protection bits */
 
 /* Used for Macronix and Winbond flashes. */
 #define SPINOR_OP_EN4B         0xb7    /* Enter 4-byte mode */
-- 
2.1.2

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