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From:   =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <zajec5@gmail.com>
To:     Miquel Raynal <miquel.raynal@bootlin.com>,
        Richard Weinberger <richard@nod.at>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
Cc:     Mikhail Zhilkin <csharper2005@gmail.com>,
        Christian Marangi <ansuelsmth@gmail.com>,
        Wolfram Sang <wsa+renesas@sang-engineering.com>,
        Chaitanya Kulkarni <kch@nvidia.com>,
        "Martin K . Petersen" <martin.petersen@oracle.com>,
        Jens Axboe <axboe@kernel.dk>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-mtd@lists.infradead.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
Subject: [PATCH 2/2] mtd: core: set ROOT_DEV for partitions marked as root devices in DT
Date:   Wed, 19 Oct 2022 13:50:41 +0200
Message-Id: <20221019115041.31805-1-zajec5@gmail.com>
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From: Rafał Miłecki <rafal@milecki.pl>

This adds support for "linux,root-device" binding that is used to mark
root device MTD partition. It's useful for devices using device tree
that don't have bootloader passing root info in cmdline.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
 drivers/mtd/mtdcore.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 07249af4f890..034b06aff660 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -28,6 +28,7 @@
 #include <linux/leds.h>
 #include <linux/debugfs.h>
 #include <linux/nvmem-provider.h>
+#include <linux/root_dev.h>
 
 #include <linux/mtd/mtd.h>
 #include <linux/mtd/partitions.h>
@@ -735,6 +736,12 @@ int add_mtd_device(struct mtd_info *mtd)
 		not->add(mtd);
 
 	mutex_unlock(&mtd_table_mutex);
+
+	if (of_find_property(mtd_get_of_node(mtd), "linux,rootfs", NULL)) {
+		pr_info("mtd: setting mtd%d (%s) as root device\n", mtd->index, mtd->name);
+		ROOT_DEV = MKDEV(MTD_BLOCK_MAJOR, mtd->index);
+	}
+
 	/* We _know_ we aren't being removed, because
 	   our caller is still holding us here. So none
 	   of this try_ nonsense, and no bitching about it
-- 
2.34.1