From 30a04cf5b6ffa1249df72ccd98cef05f37890f89 Mon Sep 17 00:00:00 2001
From: Daniel Golle <daniel@makrotopia.org>
Date: Thu, 6 Feb 2025 05:07:20 +0000
Subject: [PATCH] mtd: spinand: add work-around to prevent bootloader wiping
 mtdparts

ASUS makes use of U-Boot's fdt_fixup_mtdparts() function which applies
the partitions defined in U-Boot's mtdparts and mtdids environment
variables to the devicetree passed over to Linux.

The undesired side-effect is that in this way also all additional
properties and child nodes get wiped, preventing NVMEM cells to be
defined for MTD partitions or UBI volumes.

To work-around this issue, add an additional compatible string
'u-boot-dont-touch-spi-nand' which can be used instead of 'spi-nand' in
case the replacement of the MTD partitions by U-Boot should be skipped
alltogether.

In practise this is mostly relevant for SPI-NAND which anyway comes only
with two partitions nowadays: 'Bootloader' and 'UBI_DEV'. Hence this
work-around is applicable for SPI-NAND only. Similar work-arounds for
other MTD devices can be created as well should they actually be needed.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
---
 drivers/mtd/nand/spi/core.c | 2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/mtd/nand/spi/core.c
+++ b/drivers/mtd/nand/spi/core.c
@@ -1441,6 +1441,7 @@ static int spinand_remove(struct spi_mem
 
 static const struct spi_device_id spinand_ids[] = {
 	{ .name = "spi-nand" },
+	{ .name = "u-boot-dont-touch-spi-nand" },
 	{ /* sentinel */ },
 };
 MODULE_DEVICE_TABLE(spi, spinand_ids);
@@ -1448,6 +1449,7 @@ MODULE_DEVICE_TABLE(spi, spinand_ids);
 #ifdef CONFIG_OF
 static const struct of_device_id spinand_of_ids[] = {
 	{ .compatible = "spi-nand" },
+	{ .compatible = "u-boot-dont-touch-spi-nand" },
 	{ /* sentinel */ },
 };
 MODULE_DEVICE_TABLE(of, spinand_of_ids);
