[PATCH 1/4] mtd: core: Check devicetree alias for index

From: Vincent Whitchurch
Date: Mon Mar 07 2022 - 09:16:35 EST


Allow the MTD index to be specified via a devicetree alias, so that the
number does not just depend on probe order. This is useful to allow
pseudo-devices like phram to be optionally used on systems, without
having this affect the numbering of the real hardware MTD devices.

Signed-off-by: Vincent Whitchurch <vincent.whitchurch@xxxxxxxx>
---
drivers/mtd/mtdcore.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index bd4b31023c82..37c8b1b5db26 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -590,9 +590,10 @@ static int mtd_nvmem_add(struct mtd_info *mtd)

int add_mtd_device(struct mtd_info *mtd)
{
+ struct device_node *np = mtd_get_of_node(mtd);
struct mtd_info *master = mtd_get_master(mtd);
struct mtd_notifier *not;
- int i, error;
+ int i, error, ofidx;

/*
* May occur, for instance, on buggy drivers which call
@@ -631,7 +632,13 @@ int add_mtd_device(struct mtd_info *mtd)

mutex_lock(&mtd_table_mutex);

- i = idr_alloc(&mtd_idr, mtd, 0, 0, GFP_KERNEL);
+ ofidx = -1;
+ if (np)
+ ofidx = of_alias_get_id(np, "mtd");
+ if (ofidx >= 0)
+ i = idr_alloc(&mtd_idr, mtd, ofidx, ofidx + 1, GFP_KERNEL);
+ else
+ i = idr_alloc(&mtd_idr, mtd, 0, 0, GFP_KERNEL);
if (i < 0) {
error = i;
goto fail_locked;
--
2.34.1