[RFC 09/10] mtd: spi-nor: Disable hybrid mode for SPANSION S25FS-S family

[Prabhakar Kushwaha]

The S25FS-S family physical sectors may be configured as a hybrid
combination of eight 4-kB parameter sectors at the top or bottom
of the address space with all but one of the remaining sectors
being uniform size.
The default status of the flash is the hybrid architecture.
The parameter sectors and the uniform sectors have different erase
commands.

This patch disables the hybrid sector architecture which makes the
flash have uniform sector size and uniform erase command.

Signed-off-by: Rajat Srivastava <rajat.srivastava at nxp.com>
Signed-off-by: Prabhakar Kushwaha <prabhakar.kushwaha at nxp.com>
---
 drivers/mtd/spi-nor/spi-nor.c | 49 +++++++++++++++++++++++++++++++++++++++++++
 include/linux/mtd/spi-nor.h   |  1 +
 2 files changed, 50 insertions(+)

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index 58c37f6f..ca2ae44 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -1692,6 +1692,33 @@ static int spansion_dummy_config(struct spi_nor *nor, u8 num_wait_states,
 	return 0;
 }
 
+static int spansion_s25fs_disable_hybrid_mode(struct spi_nor *nor)
+{
+	u8 cr3v = 0x0;
+	int ret = 0x0;
+
+	ret = nor->read_anyreg(nor, SPINOR_OP_RDAR, SPANSION_CR3V_OFF,
+			       &cr3v, 1);
+	if (ret < 0) {
+		dev_err(nor->dev, "error %d reading CR3V\n", ret);
+		return ret;
+	}
+
+	/* CR3V bit3: 4-KB Erase */
+	if (cr3v & SPANSION_CR3V_4KB_ERASE_DISABLE)
+		return 0;
+
+	cr3v |= SPANSION_CR3V_4KB_ERASE_DISABLE;
+	ret = nor->write_anyreg(nor, SPINOR_OP_RDAR, SPANSION_CR3V_OFF,
+				&cr3v, 1);
+	if (ret < 0) {
+		dev_err(nor->dev, "error %d writing CR3V\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
 static int spi_nor_check(struct spi_nor *nor)
 {
 	if (!nor->dev || !nor->read || !nor->write ||
@@ -2939,6 +2966,28 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
 			return ret;
 	}
 
+	/*
+	 * The S25FS-S family physical sectors may be configured as a
+	 * hybrid combination of eight 4-kB parameter sectors
+	 * at the top or bottom of the address space with all
+	 * but one of the remaining sectors being uniform size.
+	 * The Parameter Sector Erase commands (20h or 21h) must
+	 * be used to erase the 4-kB parameter sectors individually.
+	 * The Sector (uniform sector) Erase commands (D8h or DCh)
+	 * must be used to erase any of the remaining
+	 * sectors, including the portion of highest or lowest address
+	 * sector that is not overlaid by the parameter sectors.
+	 * The uniform sector erase command has no effect on parameter sectors.
+	 * The following code removes the 4-kB parameter sectors from the
+	 * address map i.e. it disables the hybrid mode so that all sectors are
+	 * uniform size.
+	 */
+	if (JEDEC_EXT_ID(info) == SPINOR_S25FS_FAMILY_ID) {
+		ret = spansion_s25fs_disable_hybrid_mode(nor);
+		if (ret)
+			return ret;
+	}
+
 	dev_info(dev, "%s (%lld Kbytes)\n", info->name,
 			(long long)mtd->size >> 10);
 
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index 9ff96cb..6c34e00 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -115,6 +115,7 @@
 #define SPANSION_CR1V_OFF	0x00800002 /* CR1V offset */
 #define SPANSION_CR2V_OFF	0x00800003 /* CR2V offset */
 #define SPANSION_CR3V_OFF	0x00800004 /* CR3V offset */
+#define SPANSION_CR3V_4KB_ERASE_DISABLE	0x8
 
 
 /* Used for Micron flashes only. */
-- 
2.7.4