mtd: uclass: add probe function

The user might want to trigger the probe of any MTD device, export these
functions so they can be called from a command source file.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Acked-by: Jagan Teki <jagan@openedev.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com>

drivers/mtd/mtd-uclass.c

@@ -5,9 +5,25 @@
 
 #include <common.h>
 #include <dm.h>
+#include <dm/device-internal.h>
 #include <errno.h>
 #include <mtd.h>
 
+/**
+ * mtd_probe - Probe the device @dev if not already done
+ *
+ * @dev: U-Boot device to probe
+ *
+ * @return 0 on success, an error otherwise.
+ */
+int mtd_probe(struct udevice *dev)
+{
+	if (device_active(dev))
+		return 0;
+
+	return device_probe(dev);
+}
+
 /*
  * Implement a MTD uclass which should include most flash drivers.
  * The uclass private is pointed to mtd_info.

include/mtd.h

@@ -8,4 +8,6 @@
 
 #include <linux/mtd/mtd.h>
 
+int mtd_probe(struct udevice *dev);
+
 #endif	/* _MTD_H_ */