mtd: add get/set of_node/flash_node helpers

Linux commit 28b8b26b308 ("mtd: add get/set of_node/flash_node helpers")

We are going to begin using the mtd->dev.of_node field for MTD device
nodes, so let's add helpers for it. Also, we'll be making some
conversions on spi_nor (and nand_chip eventually) too, so get that ready
with their own helpers.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>
[Philippe Reynes: only add function nand_set_flash_node and
nand_get_flash_node because others were already backported]

Signed-off-by: Philippe Reynes <philippe.reynes@softathome.com>
diff --git a/include/linux/mtd/rawnand.h b/include/linux/mtd/rawnand.h
index 9f5dc81..e2bd598 100644
--- a/include/linux/mtd/rawnand.h
+++ b/include/linux/mtd/rawnand.h
@@ -15,6 +15,7 @@
 
 #include <config.h>
 
+#include <dm/device.h>
 #include <linux/compat.h>
 #include <linux/mtd/mtd.h>
 #include <linux/mtd/flashchip.h>
@@ -961,6 +962,17 @@
 	void *priv;
 };
 
+static inline void nand_set_flash_node(struct nand_chip *chip,
+				       ofnode node)
+{
+	chip->flash_node = ofnode_to_offset(node);
+}
+
+static inline ofnode nand_get_flash_node(struct nand_chip *chip)
+{
+	return offset_to_ofnode(chip->flash_node);
+}
+
 static inline struct nand_chip *mtd_to_nand(struct mtd_info *mtd)
 {
 	return container_of(mtd, struct nand_chip, mtd);