Bluetooth: Mesh: Add external flash support to DFU samples on nRF54L

This adds the required application configuration and mcuboot
configuration required to make the DFU samples work with the `ext_flash`
file suffix on both nRF52840 and nRF54L15 DKs.

Signed-off-by: Ludvig Jordet <[email protected]>

Author: ludvigsj

doc/nrf/releases_and_maturity/releases/release-notes-changelog.rst

@@ -333,11 +333,11 @@ Bluetooth Mesh samples
 
 * :ref:`ble_mesh_dfu_distributor` sample:
 
-  * Added support for external flash memory for the ``nrf52840dk/nrf52840`` as the secondary partition for the DFU process.
+  * Added support for external flash memory for the ``nrf52840dk/nrf52840`` and the ``nrf54l15dk/nrf54l15/cpuapp`` as the secondary partition for the DFU process.
 
 * :ref:`ble_mesh_dfu_target` sample:
 
-  * Added support for external flash memory for the ``nrf52840dk/nrf52840`` as the secondary partition for the DFU process.
+  * Added support for external flash memory for the ``nrf52840dk/nrf52840`` and the ``nrf54l15dk/nrf54l15/cpuapp`` as the secondary partition for the DFU process.
 
 * :ref:`bluetooth_mesh_sensor_client` sample:
 

samples/bluetooth/mesh/dfu/distributor/README.rst

@@ -254,7 +254,7 @@ Build the sample using the following command:
 .. note::
    The external flash is not erased during the internal flash erasing procedure.
    See `nRF Util`_ for more information on how to erase the external flash.
-   Currently, only the external flash on the ``nrf52840dk/nrf52840`` board is supported at the moment.
+   Currently, external flash is supported on the ``nrf52840dk/nrf52840`` board and the ``nrf54l15dk/nrf54l15/cpuapp`` board.
 
 Dependencies
 ************

samples/bluetooth/mesh/dfu/distributor/sysbuild/distributor_ext_flash.overlay renamed to samples/bluetooth/mesh/dfu/distributor/app_ext_flash.overlay

@@ -0,0 +1,31 @@
+#
+# Copyright (c) 2024 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+################################################################################
+# Application overlay - nrf54l15
+
+CONFIG_SOC_FLASH_NRF_PARTIAL_ERASE=n
+CONFIG_NVS=n
+CONFIG_NVS_LOOKUP_CACHE=n
+CONFIG_SETTINGS_NVS_NAME_CACHE=n
+CONFIG_ZMS=y
+CONFIG_SETTINGS_ZMS_CUSTOM_SECTOR_COUNT=y
+CONFIG_SETTINGS_ZMS_SECTOR_COUNT=8
+CONFIG_ZMS_LOOKUP_CACHE=y
+CONFIG_ZMS_LOOKUP_CACHE_SIZE=512
+CONFIG_ZMS_LOOKUP_CACHE_FOR_SETTINGS=y
+CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=4096
+CONFIG_BT_RX_STACK_SIZE=5120
+CONFIG_SHELL_STACK_SIZE=2560
+
+# External flash specific settings
+CONFIG_GPIO=y
+CONFIG_SPI=y
+CONFIG_SPI_NOR=y
+CONFIG_SPI_NOR_SFDP_DEVICETREE=y
+CONFIG_SPI_NOR_FLASH_LAYOUT_PAGE_SIZE=4096
+# QSPI drivers are enabled by default for some chips.
+# Disable it explicitly to be sure QSPI is disabled.
+CONFIG_NORDIC_QSPI_NOR=n

samples/bluetooth/mesh/dfu/distributor/boards/nrf54l15dk_nrf54l15_cpuapp_ext_flash.conf

@@ -0,0 +1,10 @@
+/* Copyright (c) 2025 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+ */
+
+/ {
+	chosen {
+		zephyr,code-partition = &boot_partition;
+	};
+};

samples/bluetooth/mesh/dfu/distributor/sysbuild/mcuboot.conf

@@ -0,0 +1,12 @@
+CONFIG_GPIO=y
+CONFIG_SPI=y
+CONFIG_SPI_NOR=y
+CONFIG_SPI_NOR_SFDP_DEVICETREE=y
+CONFIG_FLASH=y
+CONFIG_MAIN_STACK_SIZE=20480
+CONFIG_BOOT_MAX_IMG_SECTORS=512
+CONFIG_SPI_NOR_FLASH_LAYOUT_PAGE_SIZE=4096
+# Ensure that the qspi driver is disabled by default
+CONFIG_NORDIC_QSPI_NOR=n
+
+CONFIG_MULTITHREADING=y

samples/bluetooth/mesh/dfu/distributor/sysbuild/mcuboot/app.overlay

@@ -0,0 +1,48 @@
+/ {
+	chosen {
+		nordic,pm-ext-flash = &mx25r64;
+		zephyr,code-partition = &boot_partition;
+	};
+};
+
+/delete-node/ &boot_partition;
+/delete-node/ &slot0_partition;
+/delete-node/ &slot1_partition;
+
+/delete-node/ &storage_partition;
+
+&cpuapp_rram {
+	reg = < 0x0 DT_SIZE_K(1524) >;
+
+	partitions {
+		boot_partition: partition@0 {
+			label = "mcuboot";
+			reg = <0x000000000 0x00014000>;
+		};
+
+		slot0_partition: partition@14000 {
+			label = "image-0";
+			reg = <0x000014000 0x0015A000>;
+		};
+
+		storage_partition: partition@16E000 {
+			label = "storage";
+			reg = < 0x16E000 0x9000 >;
+		};
+	};
+};
+
+&mx25r64 {
+	status = "okay";
+
+	partitions {
+		compatible = "fixed-partitions";
+		#address-cells = <1>;
+		#size-cells = <1>;
+
+		slot1_partition: partition@0 {
+			label = "image-1";
+			reg = <0x000000000 0x0015A000>;
+		};
+	};
+};