mtd: rawnand: gpmi: set chip->of_node to nand@0 child node if present

The nand-controller.yaml binding requires a child node (e.g. nand@0) under
the NAND controller. However, the driver currently assigns the controller's
of_node directly to the NAND chip.

Search for the first child node with the "nand" prefix and assign it to
chip->of_node. This filters out properties such as "partition" that may be
placed under the controller node in some older DTS files.

Fall back to using the controller's of_node if no suitable child node is
found to maintain backward compatibility.

This issue went unnoticed because the default behavior works for most NAND
chips.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

Author: nxpfrankli

drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c

@@ -5,6 +5,7 @@
  * Copyright (C) 2010-2015 Freescale Semiconductor, Inc.
  * Copyright (C) 2008 Embedded Alley Solutions, Inc.
  */
+#include <linux/cleanup.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/slab.h>
@@ -2688,7 +2689,15 @@ static int gpmi_nand_init(struct gpmi_nand_data *this)
 
 	/* init the nand_chip{}, we don't support a 16-bit NAND Flash bus. */
 	nand_set_controller_data(chip, this);
-	nand_set_flash_node(chip, this->pdev->dev.of_node);
+
+	struct device_node *np __free(device_node) =
+		of_get_next_child_with_prefix(this->pdev->dev.of_node, NULL, "nand");
+
+	if (np)
+		nand_set_flash_node(chip, np);
+	else
+		nand_set_flash_node(chip, this->pdev->dev.of_node);
+
 	chip->legacy.block_markbad = gpmi_block_markbad;
 	chip->badblock_pattern	= &gpmi_bbt_descr;
 	chip->options		|= NAND_NO_SUBPAGE_WRITE;