3 files changed, 19 insertions, 0 deletions

diff --git a/Documentation/mtd/spi-nor.txt b/Documentation/mtd/spi-nor.txt
index 548d6306ebca..da1fbff5a24c 100644
--- a/Documentation/mtd/spi-nor.txt
+++ b/Documentation/mtd/spi-nor.txt
@@ -60,3 +60,6 @@ The main API is spi_nor_scan(). Before you call the hook, a driver should
 initialize the necessary fields for spi_nor{}. Please see
 drivers/mtd/spi-nor/spi-nor.c for detail. Please also refer to fsl-quadspi.c
 when you want to write a new driver for a SPI NOR controller.
+Another API is spi_nor_restore(), this is used to restore the status of SPI
+flash chip such as addressing mode. Call it whenever detach the driver from
+device or reboot the system.
diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index 1e4b4dfe26b5..9178139a39d0 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -2740,6 +2740,16 @@ static void spi_nor_resume(struct mtd_info *mtd)
                 dev_err(dev, "resume() failed\n");
 }
 
+void spi_nor_restore(struct spi_nor *nor)
+{
+        /* restore the addressing mode */
+        if ((nor->addr_width == 4) &&
+            (JEDEC_MFR(nor->info) != SNOR_MFR_SPANSION) &&
+            !(nor->info->flags & SPI_NOR_4B_OPCODES))
+                set_4byte(nor, nor->info, 0);
+}
+EXPORT_SYMBOL_GPL(spi_nor_restore);
+
 int spi_nor_scan(struct spi_nor *nor, const char *name,
                  const struct spi_nor_hwcaps *hwcaps)
 {
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index c0836cca5280..de36969eb359 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -403,4 +403,10 @@ struct spi_nor_hwcaps {
 int spi_nor_scan(struct spi_nor *nor, const char *name,
                  const struct spi_nor_hwcaps *hwcaps);
 
+/**
+ * spi_nor_restore_addr_mode() - restore the status of SPI NOR
+ * @nor:        the spi_nor structure
+ */
+void spi_nor_restore(struct spi_nor *nor);
+
 #endif