[RFC PATCH 1/3] mtd: spi-nor: sfdp: remember sfdp_size

[Michael Walle]

Save the sftp_size in the spi_nor struct so we can use it to dump the
SFDP table without parsing the headers again.

Signed-off-by: Michael Walle <michael@xxxxxxxx>
---
 drivers/mtd/spi-nor/sfdp.c  | 12 ++++++++++++
 include/linux/mtd/spi-nor.h |  1 +
 2 files changed, 13 insertions(+)

diff --git a/drivers/mtd/spi-nor/sfdp.c b/drivers/mtd/spi-nor/sfdp.c
index 25142ec4737b..b1814afefc33 100644
--- a/drivers/mtd/spi-nor/sfdp.c
+++ b/drivers/mtd/spi-nor/sfdp.c
@@ -16,6 +16,7 @@
 	(((p)->parameter_table_pointer[2] << 16) | \
 	 ((p)->parameter_table_pointer[1] <<  8) | \
 	 ((p)->parameter_table_pointer[0] <<  0))
+#define SFDP_PARAM_HEADER_PARAM_LEN(p) ((p)->length * 4)
 
 #define SFDP_BFPT_ID		0xff00	/* Basic Flash Parameter Table */
 #define SFDP_SECTOR_MAP_ID	0xff81	/* Sector Map Table */
@@ -1263,6 +1264,7 @@ int spi_nor_parse_sfdp(struct spi_nor *nor,
 	struct sfdp_parameter_header *param_headers = NULL;
 	struct sfdp_header header;
 	struct device *dev = nor->dev;
+	size_t param_max_offset;
 	size_t psize;
 	int i, err;
 
@@ -1285,6 +1287,9 @@ int spi_nor_parse_sfdp(struct spi_nor *nor,
 	    bfpt_header->major != SFDP_JESD216_MAJOR)
 		return -EINVAL;
 
+	nor->sfdp_size = SFDP_PARAM_HEADER_PTP(bfpt_header) +
+			 SFDP_PARAM_HEADER_PARAM_LEN(bfpt_header);
+
 	/*
 	 * Allocate memory then read all parameter headers with a single
 	 * Read SFDP command. These parameter headers will actually be parsed
@@ -1311,6 +1316,13 @@ int spi_nor_parse_sfdp(struct spi_nor *nor,
 		}
 	}
 
+	for (i = 0; i < header.nph; i++) {
+		param_header = &param_headers[i];
+		param_max_offset = SFDP_PARAM_HEADER_PTP(param_header) +
+				   SFDP_PARAM_HEADER_PARAM_LEN(param_header);
+		nor->sfdp_size = max(nor->sfdp_size, param_max_offset);
+	}
+
 	/*
 	 * Check other parameter headers to get the latest revision of
 	 * the basic flash parameter table.
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index a0d572855444..a58118b8b002 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -404,6 +404,7 @@ struct spi_nor {
 	bool			sst_write_second;
 	u32			flags;
 	enum spi_nor_cmd_ext	cmd_ext_type;
+	size_t			sfdp_size;
 
 	const struct spi_nor_controller_ops *controller_ops;
 
-- 
2.20.1