[PATCH 5/7] mtd: spi-nor: Introduce Manufacturer ID collisions driver

[Tudor Ambarus <tudor.ambarus@microchip.com>]

Some manufacturers completely ignore the manufacturer's identification code
standard (JEP106) and do not define the manufacturer ID continuation
scheme. This will result in manufacturer ID collisions.

An an example, JEP106BA requires Boya that it's manufacturer ID to be
preceded by 8 continuation codes. Boya's identification code must be:
0x7f, 0x7f, 0x7f, 0x7f, 0x7f, 0x7f, 0x7f, 0x7f, 0x68. But Boya ignores the
continuation scheme and its ID collides with the manufacturer defined in
bank one: Convex Computer.

Introduce the manuf-id-collisions driver in order to address ID collisions
between manufacturers. flash_info entries will be added in a first come,
first served manner. Differentiation between flashes will be done at
runtime if possible. Where runtime differentiation is not possible, new
compatibles will be introduced, but this will be done as a last resort.
Every new flash addition that define the SFDP tables, should dump its SFDP
tables in the patch's comment section below the --- line, so that we can
reference it in case of collisions.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
---
 drivers/mtd/spi-nor/Makefile              |  1 +
 drivers/mtd/spi-nor/core.c                |  1 +
 drivers/mtd/spi-nor/core.h                |  1 +
 drivers/mtd/spi-nor/manuf-id-collisions.c | 17 +++++++++++++++++
 4 files changed, 20 insertions(+)
 create mode 100644 drivers/mtd/spi-nor/manuf-id-collisions.c

diff --git a/drivers/mtd/spi-nor/Makefile b/drivers/mtd/spi-nor/Makefile
index 6b904e439372..48763d10daad 100644
--- a/drivers/mtd/spi-nor/Makefile
+++ b/drivers/mtd/spi-nor/Makefile
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 
 spi-nor-objs			:= core.o sfdp.o swp.o otp.o sysfs.o
+spi-nor-objs			+= manuf-id-collisions.o
 spi-nor-objs			+= atmel.o
 spi-nor-objs			+= catalyst.o
 spi-nor-objs			+= eon.o
diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index d528e28995c6..206a54c20fef 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -1829,6 +1829,7 @@ int spi_nor_sr2_bit7_quad_enable(struct spi_nor *nor)
 }
 
 static const struct spi_nor_manufacturer *manufacturers[] = {
+	&spi_nor_manuf_id_collisions,
 	&spi_nor_atmel,
 	&spi_nor_catalyst,
 	&spi_nor_eon,
diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
index 55fceb0ec894..e9896cd60695 100644
--- a/drivers/mtd/spi-nor/core.h
+++ b/drivers/mtd/spi-nor/core.h
@@ -476,6 +476,7 @@ struct sfdp {
 };
 
 /* Manufacturer drivers. */
+extern const struct spi_nor_manufacturer spi_nor_manuf_id_collisions;
 extern const struct spi_nor_manufacturer spi_nor_atmel;
 extern const struct spi_nor_manufacturer spi_nor_catalyst;
 extern const struct spi_nor_manufacturer spi_nor_eon;
diff --git a/drivers/mtd/spi-nor/manuf-id-collisions.c b/drivers/mtd/spi-nor/manuf-id-collisions.c
new file mode 100644
index 000000000000..9efcba9d18a0
--- /dev/null
+++ b/drivers/mtd/spi-nor/manuf-id-collisions.c
@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/mtd/spi-nor.h>
+#include "core.h"
+
+static const struct flash_info id_collision_parts[] = {
+	/* Boya */
+	{ "by25q128as", INFO(0x684018, 0, 64 * 1024, 256, SPI_NOR_SKIP_SFDP |
+			     SECT_4K | SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ |
+			     SPI_NOR_HAS_LOCK | SPI_NOR_HAS_TB) },
+};
+
+const struct spi_nor_manufacturer spi_nor_manuf_id_collisions = {
+	.name = "manufacturer ID collisions",
+	.parts = id_collision_parts,
+	.nparts = ARRAY_SIZE(id_collision_parts),
+};
-- 
2.25.1


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