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Subject[PATCH v4 2/6] mtd: rawnand: add an option to specify NAND chip as a boot device
Date
Allow to define a NAND chip as a boot device. This can be helpful
for the selection of the ECC algorithm and strength in case the boot
ROM supports only a subset of controller provided options.

Signed-off-by: Stefan Agner <stefan@agner.ch>
Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com>
---
Documentation/devicetree/bindings/mtd/nand.txt | 4 ++++
drivers/mtd/nand/raw/nand_base.c | 3 +++
include/linux/mtd/rawnand.h | 6 ++++++
3 files changed, 13 insertions(+)

diff --git a/Documentation/devicetree/bindings/mtd/nand.txt b/Documentation/devicetree/bindings/mtd/nand.txt
index eaef8c657aa5..e949c778e983 100644
--- a/Documentation/devicetree/bindings/mtd/nand.txt
+++ b/Documentation/devicetree/bindings/mtd/nand.txt
@@ -43,6 +43,10 @@ Optional NAND chip properties:
This is particularly useful when only the in-band area is
used by the upper layers, and you want to make your NAND
as reliable as possible.
+- nand-is-boot-medium: Whether the NAND chip is a boot medium. Drivers might use
+ this information to select ECC algorithms supported by
+ the boot ROM or similar restrictions.
+
- nand-rb: shall contain the native Ready/Busy ids.

The ECC strength and ECC step size properties define the correction capability
diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
index 9eb5678dd6d0..c8fb7c9855e2 100644
--- a/drivers/mtd/nand/raw/nand_base.c
+++ b/drivers/mtd/nand/raw/nand_base.c
@@ -5826,6 +5826,9 @@ static int nand_dt_init(struct nand_chip *chip)
if (of_get_nand_bus_width(dn) == 16)
chip->options |= NAND_BUSWIDTH_16;

+ if (of_property_read_bool(dn, "nand-is-boot-medium"))
+ chip->options |= NAND_IS_BOOT_MEDIUM;
+
if (of_get_nand_on_flash_bbt(dn))
chip->bbt_options |= NAND_BBT_USE_FLASH;

diff --git a/include/linux/mtd/rawnand.h b/include/linux/mtd/rawnand.h
index 6a82da8c44ce..8e54fcf2fa94 100644
--- a/include/linux/mtd/rawnand.h
+++ b/include/linux/mtd/rawnand.h
@@ -212,6 +212,12 @@ enum nand_ecc_algo {
*/
#define NAND_WAIT_TCCS 0x00200000

+/*
+ * Whether the NAND chip is a boot medium. Drivers might use this information
+ * to select ECC algorithms supported by the boot ROM or similar restrictions.
+ */
+#define NAND_IS_BOOT_MEDIUM 0x00400000
+
/* Options set by nand scan */
/* Nand scan has allocated controller struct */
#define NAND_CONTROLLER_ALLOC 0x80000000
--
2.17.1
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