[PATCH V3 1/2] mtd: allow getting MTD device associated with a specific DT node

Rafał Miłecki
2022-06-11T20:47:29Z

From: Rafał Miłecki <rafal@milecki.pl>

MTD subsystem API allows interacting with MTD devices (e.g. reading,
writing, handling bad blocks). So far a random driver could get MTD
device only by its name (get_mtd_device_nm()). This change allows
getting them also by a DT node.

This API is required for drivers handling DT defined MTD partitions in a
specific way (e.g. U-Boot (sub)partition with environment variables).

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
V3: First introduction of of_get_mtd_device_by_node()

mtd maintainers: please let know how would you like this patch
processed. Would that be OK for you to Review/Ack it and let it go
through NVMEM tree?
---
drivers/mtd/mtdcore.c | 28 ++++++++++++++++++++++++++++
include/linux/mtd/mtd.h | 1 +
2 files changed, 29 insertions(+)

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 9eb0680db312..7dc214271c85 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -1154,6 +1154,34 @@ int __get_mtd_device(struct mtd_info *mtd)
}
EXPORT_SYMBOL_GPL(__get_mtd_device);

+/**
+ * of_get_mtd_device_by_node - obtain an MTD device associated with a given node
+ *
+ * @np: device tree node
+ */
+struct mtd_info *of_get_mtd_device_by_node(struct device_node *np)
+{
+ struct mtd_info *mtd = NULL;
+ struct mtd_info *tmp;
+ int err;
+
+ mutex_lock(&mtd_table_mutex);
+
+ err = -ENODEV;
+ mtd_for_each_device(tmp) {
+ if (mtd_get_of_node(tmp) == np) {
+ mtd = tmp;
+ err = __get_mtd_device(mtd);
+ break;
+ }
+ }
+
+ mutex_unlock(&mtd_table_mutex);
+
+ return err ? ERR_PTR(err) : mtd;
+}
+EXPORT_SYMBOL_GPL(of_get_mtd_device_by_node);
+
/**
* get_mtd_device_nm - obtain a validated handle for an MTD device by
* device name
diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
index 955aee14b0f7..6fc841ceef31 100644
--- a/include/linux/mtd/mtd.h
+++ b/include/linux/mtd/mtd.h
@@ -677,6 +677,7 @@ extern int mtd_device_unregister(struct mtd_info *master);
extern struct mtd_info *get_mtd_device(struct mtd_info *mtd, int num);
extern int __get_mtd_device(struct mtd_info *mtd);
extern void __put_mtd_device(struct mtd_info *mtd);
+extern struct mtd_info *of_get_mtd_device_by_node(struct device_node *np);
extern struct mtd_info *get_mtd_device_nm(const char *name);
extern void put_mtd_device(struct mtd_info *mtd);

--
2.34.1