mtd: spi-nor: provide default erase_sector implementation

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>

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 16c9f5522b8f..a38ec01a1e06 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 955f268d159a..7bed97471e53 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -143,7 +143,8 @@ 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