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Subject[PATCH 5/6] mtd: spi-nor: add generic flash driver
Date
Our SFDP is 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.

It is still recommended to add the flash to the in-kernel database.
First, we get a proper partname and secondly, for all features not
described by the SFDP like OTP we need the entry anyway.

Signed-off-by: Michael Walle <michael@walle.cc>
---
drivers/mtd/spi-nor/core.c | 13 +++++++++++++
drivers/mtd/spi-nor/core.h | 1 +
drivers/mtd/spi-nor/sfdp.c | 27 +++++++++++++++++++++++++++
3 files changed, 41 insertions(+)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index 65cd8e668579..ee193a61310a 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -1632,6 +1632,11 @@ static const struct spi_nor_manufacturer *manufacturers[] = {
&spi_nor_xmc,
};

+static const struct flash_info spi_nor_generic_flash = {
+ .name = "spi-nor-generic",
+ .parse_sfdp = true,
+};
+
static const struct flash_info *spi_nor_match_id(struct spi_nor *nor,
const u8 *id)
{
@@ -1670,6 +1675,14 @@ 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);
diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
index 3a19b8092ab8..aa9f218245a5 100644
--- a/drivers/mtd/spi-nor/core.h
+++ b/drivers/mtd/spi-nor/core.h
@@ -694,6 +694,7 @@ 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 a5211543d30d..9bdb3d5dc7e8 100644
--- a/drivers/mtd/spi-nor/sfdp.c
+++ b/drivers/mtd/spi-nor/sfdp.c
@@ -1247,6 +1247,33 @@ static void spi_nor_post_sfdp_fixups(struct spi_nor *nor)
nor->info->fixups->post_sfdp(nor);
}

+/**
+ * spi_nor_check_sfdp_header() - check for a valid SFDP header
+ * @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'
--
2.30.2
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