[PATCH v2 1/2] mtd: spi-nor: provide default erase_sector implementation

[PATCH v2 1/2] mtd: spi-nor: provide default erase_sector implementation

[Brian Norris]

Some spi-nor drivers perform sector erase by duplicating their
write_reg() command. Let's not require that the driver fill this out,
and provide a default instead.

Tested on m25p80.c and Medatek's MT8173 SPI NOR flash driver.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
---
v1 -> v2:
  * use statically-sized array, with a check to make sure MAX is big enough

v1: http://lists.infradead.org/pipermail/linux-mtd/2015-October/062916.html

 drivers/mtd/spi-nor/spi-nor.c | 37 +++++++++++++++++++++++++++++++++----
 include/linux/mtd/spi-nor.h   |  3 ++-
 2 files changed, 35 insertions(+), 5 deletions(-)

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index 49883905a434..aa85564cf25a 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -38,6 +38,7 @@
 #define CHIP_ERASE_2MB_READY_WAIT_JIFFIES	(40UL * HZ)
 
 #define SPI_NOR_MAX_ID_LEN	6
+#define SPI_NOR_MAX_ADDR_WIDTH	4
 
 struct flash_info {
 	char		*name;
@@ -313,6 +314,29 @@ static void spi_nor_unlock_and_unprep(struct spi_nor *nor, enum spi_nor_ops ops)
 }
 
 /*
+ * Initiate the erasure of a single sector
+ */
+static int spi_nor_erase_sector(struct spi_nor *nor, u32 addr)
+{
+	u8 buf[SPI_NOR_MAX_ADDR_WIDTH];
+	int i;
+
+	if (nor->erase)
+		return nor->erase(nor, addr);
+
+	/*
+	 * Default implementation, if driver doesn't have a specialized HW
+	 * control
+	 */
+	for (i = nor->addr_width - 1; i >= 0; i--) {
+		buf[i] = addr & 0xff;
+		addr >>= 8;
+	}
+
+	return nor->write_reg(nor, nor->erase_opcode, buf, nor->addr_width);
+}
+
+/*
  * Erase an address range on the nor chip.  The address range may extend
  * one or more erase sectors.  Return an error is there is a problem erasing.
  */
@@ -371,10 +395,9 @@ static int spi_nor_erase(struct mtd_info *mtd, struct erase_info *instr)
 		while (len) {
 			write_enable(nor);
 
-			if (nor->erase(nor, addr)) {
-				ret = -EIO;
+			ret = spi_nor_erase_sector(nor, addr);
+			if (ret)
 				goto erase_err;
-			}
 
 			addr += mtd->erasesize;
 			len -= mtd->erasesize;
@@ -1138,7 +1161,7 @@ static int set_quad_mode(struct spi_nor *nor, const struct flash_info *info)
 static int spi_nor_check(struct spi_nor *nor)
 {
 	if (!nor->dev || !nor->read || !nor->write ||
-		!nor->read_reg || !nor->write_reg || !nor->erase) {
+		!nor->read_reg || !nor->write_reg) {
 		pr_err("spi-nor: please fill all the necessary fields!\n");
 		return -EINVAL;
 	}
@@ -1340,6 +1363,12 @@ int spi_nor_scan(struct spi_nor *nor, const char *name, enum read_mode mode)
 		nor->addr_width = 3;
 	}
 
+	if (nor->addr_width > SPI_NOR_MAX_ADDR_WIDTH) {
+		dev_err(dev, "address width is too large: %u\n",
+			nor->addr_width);
+		return -EINVAL;
+	}
+
 	nor->read_dummy = spi_nor_read_dummy_cycles(nor);
 
 	dev_info(dev, "%s (%lld Kbytes)\n", info->name,
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index c8723b62c4cd..69898b675ade 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -144,7 +144,8 @@ struct mtd_info;
  * @read:		[DRIVER-SPECIFIC] read data from the SPI NOR
  * @write:		[DRIVER-SPECIFIC] write data to the SPI NOR
  * @erase:		[DRIVER-SPECIFIC] erase a sector of the SPI NOR
- *			at the offset @offs
+ *			at the offset @offs; if not provided by the driver,
+ *			spi-nor will send the erase opcode via write_reg()
  * @flash_lock:		[FLASH-SPECIFIC] lock a region of the SPI NOR
  * @flash_unlock:	[FLASH-SPECIFIC] unlock a region of the SPI NOR
  * @flash_is_locked:	[FLASH-SPECIFIC] check if a region of the SPI NOR is
-- 
2.6.0.rc2.230.g3dd15c0

[PATCH v2 2/2] mtd: m25p80: drop erase() callback

[Brian Norris]

Just use the spi-nor default instead.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
---
v2: no change

v1: http://lists.infradead.org/pipermail/linux-mtd/2015-October/062917.html

 drivers/mtd/devices/m25p80.c | 17 -----------------
 1 file changed, 17 deletions(-)

diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index 4b5d7a4655fd..822b6c73dd50 100644
--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c
@@ -152,22 +152,6 @@ static int m25p80_read(struct spi_nor *nor, loff_t from, size_t len,
 	return 0;
 }
 
-static int m25p80_erase(struct spi_nor *nor, loff_t offset)
-{
-	struct m25p *flash = nor->priv;
-
-	dev_dbg(nor->dev, "%dKiB at 0x%08x\n",
-		flash->spi_nor.mtd.erasesize / 1024, (u32)offset);
-
-	/* Set up command buffer. */
-	flash->command[0] = nor->erase_opcode;
-	m25p_addr2cmd(nor, offset, flash->command);
-
-	spi_write(flash->spi, flash->command, m25p_cmdsz(nor));
-
-	return 0;
-}
-
 /*
  * board specific setup should have ensured the SPI clock used here
  * matches what the READ command supports, at least until this driver
@@ -194,7 +178,6 @@ static int m25p_probe(struct spi_device *spi)
 	/* install the hooks */
 	nor->read = m25p80_read;
 	nor->write = m25p80_write;
-	nor->erase = m25p80_erase;
 	nor->write_reg = m25p80_write_reg;
 	nor->read_reg = m25p80_read_reg;
 
-- 
2.6.0.rc2.230.g3dd15c0

Re: [PATCH v2 1/2] mtd: spi-nor: provide default erase_sector implementation

[Brian Norris]

On Tue, Nov 10, 2015 at 12:15:27PM -0800, Brian Norris wrote:
> Some spi-nor drivers perform sector erase by duplicating their
> write_reg() command. Let's not require that the driver fill this out,
> and provide a default instead.
> 
> Tested on m25p80.c and Medatek's MT8173 SPI NOR flash driver.
> 
> Signed-off-by: Brian Norris <computersforpeace@gmail.com>
> ---
> v1 -> v2:
>   * use statically-sized array, with a check to make sure MAX is big enough
> 
> v1: http://lists.infradead.org/pipermail/linux-mtd/2015-October/062916.html

Pushed both to l2-mtd.git