samples: smp_svr: Add experimental support for external flash on nRF54H20

Thic commit adds external flash support for nRF54H20 smp_svr sample.
This is an experimental feature and marked as DNM.

Also, CONFIG_MCUMGR_GRP_IMG_ALLOW_CONFIRM_NON_ACTIVE_IMAGE_ANY is
enabled to allow radio core image confirmation through MCUmgr commands.
It is recommended to use this feature only in development -
application should have means to test and confirm the image instead,
for e.g. using boot_write_img_confirmed() (radio app confirming itself)
or boot_write_img_confirmed_multi().

Signed-off-by: Michal Kozikowski <[email protected]>

Author: nordic-mik7

samples/zephyr/subsys/mgmt/mcumgr/smp_svr/boards/nrf54h20dk_nrf54h20_cpuapp_ext_flash.overlay

@@ -0,0 +1,7 @@
+/*
+ * Copyright (c) 2025 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+ */
+
+ #include "../sysbuild/nrf54h20dk_nrf54h20_ext_flash.dtsi"

samples/zephyr/subsys/mgmt/mcumgr/smp_svr/sample.yaml

@@ -45,3 +45,18 @@ tests:
       - nrf54h20dk/nrf54h20/cpuapp
     integration_platforms:
       - nrf54h20dk/nrf54h20/cpuapp
+  sample.mcumgr.smp_svr.bt.nrf54h20dk.ext_flash:
+    extra_args:
+      - FILE_SUFFIX="ext_flash"
+      - EXTRA_CONF_FILE="overlay-bt.conf"
+      - mcuboot_CONFIG_MULTITHREADING=y
+      - mcuboot_CONFIG_NRF_SECURITY=y
+      - mcuboot_CONFIG_BOOT_IMG_HASH_DIRECTLY_ON_STORAGE=n
+      - mcuboot_CONFIG_BOOT_MAX_IMG_SECTORS_AUTO=n
+      - mcuboot_CONFIG_BOOT_MAX_IMG_SECTORS=512
+      - mcuboot_CONFIG_FLASH_MSPI_NOR_LAYOUT_PAGE_SIZE=4096
+      - SB_CONFIG_NETCORE_IPC_RADIO=y
+      - SB_CONFIG_NETCORE_IPC_RADIO_BT_HCI_IPC=y
+      - CONFIG_MCUMGR_GRP_IMG_ALLOW_CONFIRM_NON_ACTIVE_IMAGE_ANY=y
+    platform_allow:
+      - nrf54h20dk/nrf54h20/cpuapp

samples/zephyr/subsys/mgmt/mcumgr/smp_svr/sysbuild/mcuboot_ext_flash.overlay

@@ -0,0 +1,13 @@
+/*
+ * Copyright (c) 2025 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+ */
+
+ #include "nrf54h20dk_nrf54h20_ext_flash.dtsi"
+
+ / {
+	 chosen {
+		 zephyr,code-partition = &boot_partition;
+	 };
+ };

samples/zephyr/subsys/mgmt/mcumgr/smp_svr/sysbuild/nrf54h20dk_nrf54h20_ext_flash.dtsi

@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2025 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+ */
+
+/delete-node/ &slot1_partition;
+/delete-node/ &slot3_partition;
+
+/ {
+	chosen {
+		extmem-device = &mx25uw63;
+	};
+};
+
+&mx25uw63 {
+	status = "okay";
+	partitions {
+		compatible = "fixed-partitions";
+		#address-cells = <1>;
+		#size-cells = <1>;
+
+		slot1_partition: partition@0 {
+			label = "image-1";
+			reg = <0x0 DT_SIZE_K(328)>;
+		};
+
+		slot3_partition: partition@52000 {
+			label = "image-3";
+			reg = <0x52000 DT_SIZE_K(328)>;
+		};
+	};
+};
+
+&gpio6 {
+	status = "okay";
+};
+
+&exmif {
+	status = "okay";
+};