mtd: spi-nor: add generic flash driver

Our SFDP parsing is everything we need to support all basic operations
of a flash device. If the flash isn't found in our in-kernel flash
database, gracefully fall back to a driver described solely by its SFDP
tables.

Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Tested-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Reviewed-by: Takahiro Kuwano <Takahiro.Kuwano@infineon.com>
Link: https://lore.kernel.org/r/20220810220654.1297699-7-michael@walle.cc

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index 2bdc5b5..71b9bcd 100644 (file)
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -1634,6 +1634,16 @@ static const struct spi_nor_manufacturer *manufacturers[] = {
        &spi_nor_xmc,
 };
 
+static const struct flash_info spi_nor_generic_flash = {
+       .name = "spi-nor-generic",
+       /*
+        * JESD216 rev A doesn't specify the page size, therefore we need a
+        * sane default.
+        */
+       .page_size = 256,
+       .parse_sfdp = true,
+};
+
 static const struct flash_info *spi_nor_match_id(struct spi_nor *nor,
                                                 const u8 *id)
 {
@@ -1672,6 +1682,14 @@ static const struct flash_info *spi_nor_detect(struct spi_nor *nor)
                return ERR_PTR(-ENOMEM);
 
        info = spi_nor_match_id(nor, id);
+
+       /* Fallback to a generic flash described only by its SFDP data. */
+       if (!info) {
+               ret = spi_nor_check_sfdp_signature(nor);
+               if (!ret)
+                       info = &spi_nor_generic_flash;
+       }
+
        if (!info) {
                dev_err(nor->dev, "unrecognized JEDEC id bytes: %*ph\n",
                        SPI_NOR_MAX_ID_LEN, id);
@@ -2098,8 +2116,12 @@ static int spi_nor_select_pp(struct spi_nor *nor,
  * spi_nor_select_uniform_erase() - select optimum uniform erase type
  * @map:               the erase map of the SPI NOR
  * @wanted_size:       the erase type size to search for. Contains the value of
- *                     info->sector_size or of the "small sector" size in case
- *                     CONFIG_MTD_SPI_NOR_USE_4K_SECTORS is defined.
+ *                     info->sector_size, the "small sector" size in case
+ *                     CONFIG_MTD_SPI_NOR_USE_4K_SECTORS is defined or 0 if
+ *                     there is no information about the sector size. The
+ *                     latter is the case if the flash parameters are parsed
+ *                     solely by SFDP, then the largest supported erase type
+ *                     is selected.
  *
  * Once the optimum uniform sector erase command is found, disable all the
  * other.

diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
index 68aacca..ef0a73d 100644 (file)
--- a/drivers/mtd/spi-nor/core.h
+++ b/drivers/mtd/spi-nor/core.h
@@ -701,6 +701,7 @@ int spi_nor_controller_ops_read_reg(struct spi_nor *nor, u8 opcode,
 int spi_nor_controller_ops_write_reg(struct spi_nor *nor, u8 opcode,
                                     const u8 *buf, size_t len);
 
+int spi_nor_check_sfdp_signature(struct spi_nor *nor);
 int spi_nor_parse_sfdp(struct spi_nor *nor);
 
 static inline struct spi_nor *mtd_to_spi_nor(struct mtd_info *mtd)

diff --git a/drivers/mtd/spi-nor/sfdp.c b/drivers/mtd/spi-nor/sfdp.c
index 15fb7f6..c88628e 100644 (file)
--- a/drivers/mtd/spi-nor/sfdp.c
+++ b/drivers/mtd/spi-nor/sfdp.c
@@ -1257,6 +1257,33 @@ static void spi_nor_post_sfdp_fixups(struct spi_nor *nor)
 }
 
 /**
+ * spi_nor_check_sfdp_signature() - check for a valid SFDP signature
+ * @nor:       pointer to a 'struct spi_nor'
+ *
+ * Used to detect if the flash supports the RDSFDP command as well as the
+ * presence of a valid SFDP table.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+int spi_nor_check_sfdp_signature(struct spi_nor *nor)
+{
+       u32 signature;
+       int err;
+
+       /* Get the SFDP header. */
+       err = spi_nor_read_sfdp_dma_unsafe(nor, 0, sizeof(signature),
+                                          &signature);
+       if (err < 0)
+               return err;
+
+       /* Check the SFDP signature. */
+       if (le32_to_cpu(signature) != SFDP_SIGNATURE)
+               return -EINVAL;
+
+       return 0;
+}
+
+/**
  * spi_nor_parse_sfdp() - parse the Serial Flash Discoverable Parameters.
  * @nor:               pointer to a 'struct spi_nor'
  *