From: Rafał Miłecki <rafal@milecki.pl>
Date: Sat, 22 Oct 2022 21:13:18 +0000 (+0200)
Subject: mtd: core: set ROOT_DEV for partitions marked as rootfs in DT
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=26422ac78e9d8767bd4aabfbae616b15edbf6a1b;p=linux.git

mtd: core: set ROOT_DEV for partitions marked as rootfs in DT

This adds support for "linux,rootfs" binding that is used to mark flash
partition containing rootfs. 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>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20221022211318.32009-2-zajec5@gmail.com
---

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 756fd27f4cfee..e0193054f8d9f 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>
@@ -737,6 +738,17 @@ 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)) {
+		if (IS_BUILTIN(CONFIG_MTD)) {
+			pr_info("mtd: setting mtd%d (%s) as root device\n", mtd->index, mtd->name);
+			ROOT_DEV = MKDEV(MTD_BLOCK_MAJOR, mtd->index);
+		} else {
+			pr_warn("mtd: can't set mtd%d (%s) as root device - mtd must be builtin\n",
+				mtd->index, mtd->name);
+		}
+	}
+
 	/* 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