[PATCH v8 2/6] mtd: rawnand: add an option to specify NAND chip as a boot device

From: Stefan Agner <stefan@agner.ch>
To: boris.brezillon@bootlin.com, dwmw2@infradead.org,
	computersforpeace@gmail.com, marek.vasut@gmail.com,
	robh+dt@kernel.org, mark.rutland@arm.com,
	thierry.reding@gmail.com
Cc: dev@lynxeye.de, miquel.raynal@bootlin.com, richard@nod.at,
	marcel@ziswiler.com, krzk@kernel.org, digetx@gmail.com,
	benjamin.lindqvist@endian.se, jonathanh@nvidia.com,
	pdeschrijver@nvidia.com, pgaikwad@nvidia.com,
	mirza.krak@gmail.com, gaireg@gaireg.de,
	linux-mtd@lists.infradead.org, linux-tegra@vger.kernel.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	Stefan Agner <stefan@agner.ch>
Subject: [PATCH v8 2/6] mtd: rawnand: add an option to specify NAND chip as a boot device
Date: Sun, 24 Jun 2018 23:27:23 +0200	[thread overview]
Message-ID: <20180624212727.21672-3-stefan@agner.ch> (raw)
In-Reply-To: <20180624212727.21672-1-stefan@agner.ch>

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 eaef8c657aa5c..e949c778e9837 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 47e9cb9063da4..e70bf328c64e4 100644
--- a/drivers/mtd/nand/raw/nand_base.c
+++ b/drivers/mtd/nand/raw/nand_base.c
@@ -5859,6 +5859,9 @@ 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 2d9cb7acbc3d8..80aeeca03f36b 100644
--- a/include/linux/mtd/rawnand.h
+++ b/include/linux/mtd/rawnand.h
@@ -219,6 +219,12 @@ 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
