2022-10-22 21:18:47

by Rafał Miłecki

Subject: [PATCH V3 2/2] mtd: core: set ROOT_DEV for partitions marked as rootfs in DT

From: Rafał Miłecki <[email protected]>

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 <[email protected]>
---
V2: Use "linux,rootfs" as more accurate. Thanks Rob.
V3: Add IS_BUILTIN(CONFIG_MTD) check to avoid
ERROR: modpost: "ROOT_DEV" [drivers/mtd/mtd.ko] undefined!
---
drivers/mtd/mtdcore.c | 12 ++++++++++++
1 file changed, 12 insertions(+)

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 20fcedc3021e..f70a5e66843b 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 +736,17 @@ 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
--
2.34.1

2022-11-07 16:51:21

by Miquel Raynal

Subject: Re: [PATCH V3 2/2] mtd: core: set ROOT_DEV for partitions marked as rootfs in DT

On Sat, 2022-10-22 at 21:13:18 UTC, =?utf-8?b?UmFmYcWCIE1pxYJlY2tp?= wrote:
> From: Rafał Miłecki <[email protected]>
>
> 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 <[email protected]>

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/next, thanks.

Miquel