mtd: allow getting MTD device associated with a specific DT node

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).

Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220916122100.170016-3-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index a9b8be9..e3bee27 100644 (file)
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -1218,6 +1218,34 @@ 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 = -EPROBE_DEFER;
+       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
  *     @name: MTD device name to open

diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
index 955aee1..6fc841c 100644 (file)
--- 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);