[PATCH v6 1/3] mtd: spi-nor: Add spi-nor init function

[Kamal Dasu <kdasu.kdev@gmail.com>]

Refactored spi_nor_scan() code to add spi_nor_init() function that
programs the spi-nor flash to:
1) remove flash protection if applicable for certain vendors
2) set read mode to quad mode if configured such
3) set the address width based on the flash size

spi_nor_scan() now calls spi_nor_init() to setup nor flash.
The init function can also be called by flash device driver
to reinitialize spi-nor flash.

Signed-off-by: Kamal Dasu <kdasu.kdev@gmail.com>
---
 drivers/mtd/spi-nor/spi-nor.c | 77 ++++++++++++++++++++++++++++---------------
 include/linux/mtd/spi-nor.h   | 18 +++++++++-
 2 files changed, 67 insertions(+), 28 deletions(-)

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index 70e52ff..8b71c11 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -1526,6 +1526,44 @@ static int s3an_nor_scan(const struct flash_info *info, struct spi_nor *nor)
 	return 0;
 }
 
+int spi_nor_init(struct spi_nor *nor)
+{
+	int ret = 0;
+	const struct flash_info *info = nor->info;
+	struct device *dev = nor->dev;
+
+	/*
+	 * Atmel, SST, Intel/Numonyx, and others serial NOR tend to power up
+	 * with the software protection bits set
+	 */
+
+	if (JEDEC_MFR(info) == SNOR_MFR_ATMEL ||
+	    JEDEC_MFR(info) == SNOR_MFR_INTEL ||
+	    JEDEC_MFR(info) == SNOR_MFR_SST ||
+	    info->flags & SPI_NOR_HAS_LOCK) {
+		write_enable(nor);
+		write_sr(nor, 0);
+		spi_nor_wait_till_ready(nor);
+	}
+
+	if (nor->flash_read == SPI_NOR_QUAD) {
+		ret = set_quad_mode(nor, info);
+		if (ret) {
+			dev_err(dev, "quad mode not supported\n");
+			return ret;
+		}
+	}
+
+	if (JEDEC_MFR(info) == SNOR_MFR_SPANSION ||
+	    info->flags & SPI_NOR_4B_OPCODES)
+		spi_nor_set_4byte_opcodes(nor, info);
+	else
+		set_4byte(nor, info, 1);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(spi_nor_init);
+
 int spi_nor_scan(struct spi_nor *nor, const char *name, enum read_mode mode)
 {
 	const struct flash_info *info = NULL;
@@ -1571,6 +1609,8 @@ int spi_nor_scan(struct spi_nor *nor, const char *name, enum read_mode mode)
 		}
 	}
 
+	/* update pointer to flash_info in the nor structure */
+	nor->info = info;
 	mutex_init(&nor->lock);
 
 	/*
@@ -1581,20 +1621,6 @@ int spi_nor_scan(struct spi_nor *nor, const char *name, enum read_mode mode)
 	if (info->flags & SPI_S3AN)
 		nor->flags |=  SNOR_F_READY_XSR_RDY;
 
-	/*
-	 * Atmel, SST, Intel/Numonyx, and others serial NOR tend to power up
-	 * with the software protection bits set
-	 */
-
-	if (JEDEC_MFR(info) == SNOR_MFR_ATMEL ||
-	    JEDEC_MFR(info) == SNOR_MFR_INTEL ||
-	    JEDEC_MFR(info) == SNOR_MFR_SST ||
-	    info->flags & SPI_NOR_HAS_LOCK) {
-		write_enable(nor);
-		write_sr(nor, 0);
-		spi_nor_wait_till_ready(nor);
-	}
-
 	if (!mtd->name)
 		mtd->name = dev_name(dev);
 	mtd->priv = nor;
@@ -1669,11 +1695,6 @@ int spi_nor_scan(struct spi_nor *nor, const char *name, enum read_mode mode)
 
 	/* Quad/Dual-read mode takes precedence over fast/normal */
 	if (mode == SPI_NOR_QUAD && info->flags & SPI_NOR_QUAD_READ) {
-		ret = set_quad_mode(nor, info);
-		if (ret) {
-			dev_err(dev, "quad mode not supported\n");
-			return ret;
-		}
 		nor->flash_read = SPI_NOR_QUAD;
 	} else if (mode == SPI_NOR_DUAL && info->flags & SPI_NOR_DUAL_READ) {
 		nor->flash_read = SPI_NOR_DUAL;
@@ -1702,17 +1723,11 @@ int spi_nor_scan(struct spi_nor *nor, const char *name, enum read_mode mode)
 
 	if (info->addr_width)
 		nor->addr_width = info->addr_width;
-	else if (mtd->size > 0x1000000) {
+	else if (mtd->size > 0x1000000)
 		/* enable 4-byte addressing if the device exceeds 16MiB */
 		nor->addr_width = 4;
-		if (JEDEC_MFR(info) == SNOR_MFR_SPANSION ||
-		    info->flags & SPI_NOR_4B_OPCODES)
-			spi_nor_set_4byte_opcodes(nor, info);
-		else
-			set_4byte(nor, info, 1);
-	} else {
+	else
 		nor->addr_width = 3;
-	}
 
 	if (nor->addr_width > SPI_NOR_MAX_ADDR_WIDTH) {
 		dev_err(dev, "address width is too large: %u\n",
@@ -1728,6 +1743,14 @@ int spi_nor_scan(struct spi_nor *nor, const char *name, enum read_mode mode)
 			return ret;
 	}
 
+	/*
+	 * call init function to send necessary spi-nor read/write config
+	 * commands to nor flash based on above nor settings
+	 */
+	ret = spi_nor_init(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 f2a7180..29a8283 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -143,6 +143,8 @@ enum spi_nor_option_flags {
 	SNOR_F_READY_XSR_RDY	= BIT(4),
 };
 
+struct flash_info;
+
 /**
  * struct spi_nor - Structure for defining a the SPI NOR layer
  * @mtd:		point to a mtd_info structure
@@ -174,6 +176,7 @@ enum spi_nor_option_flags {
  * @flash_is_locked:	[FLASH-SPECIFIC] check if a region of the SPI NOR is
  *			completely locked
  * @priv:		the private data
+ * @info:		points to the flash_info structure
  */
 struct spi_nor {
 	struct mtd_info		mtd;
@@ -206,6 +209,7 @@ struct spi_nor {
 	int (*flash_is_locked)(struct spi_nor *nor, loff_t ofs, uint64_t len);
 
 	void *priv;
+	const struct flash_info *info;
 };
 
 static inline void spi_nor_set_flash_node(struct spi_nor *nor,
@@ -220,12 +224,24 @@ static inline struct device_node *spi_nor_get_flash_node(struct spi_nor *nor)
 }
 
 /**
+ * spi_nor_init() - initialize SPI NOR
+ * @nor:	the spi_nor structure
+ *
+ * The drivers uses this function to initialize the SPI NOR flash device to
+ * settings in spi_nor structure. The functions sets read mode, address width
+ * and removes protection on the flash device based on those settings.
+ *
+ * Return: 0 for success, others for failure.
+ */
+int spi_nor_init(struct spi_nor *nor);
+
+/**
  * spi_nor_scan() - scan the SPI NOR
  * @nor:	the spi_nor structure
  * @name:	the chip type name
  * @mode:	the read mode supported by the driver
  *
- * The drivers can use this fuction to scan the SPI NOR.
+ * The drivers can use this function to scan the SPI NOR.
  * In the scanning, it will try to get all the necessary information to
  * fill the mtd_info{} and the spi_nor{}.
  *
-- 
1.9.1