Nucleo H723ZG : add a flash memory partition to use MCUboot

[thomasbouston]

Is your enhancement proposal related to a problem? Please describe.
Due to the absence of a flash partition, it is not possible to use MCUboot with a nucleo_h723zg board.

Describe the solution you'd like
Add a flash partition (and the Zephyr-chosen associated property) to the file zephyr/boards/st/nucleo_h723zg/nucleo_h723zg.dts.

Additional context
Adding this partition will have no impact on applications that don't use MCUboot, and will enable MCUboot to be used with this board.

Here is an example of such partition:

&flash0 {
	partitions {
		compatible = "fixed-partitions";
		#address-cells = <1>;
		#size-cells = <1>;

		/* 128KB for bootloader */
		boot_partition: partition@0 {
			label = "mcuboot";
			reg = <0x00000000 DT_SIZE_K(128)>;
			read-only;
		};

		/* primary application image slot: 384KB */
		slot0_partition: partition@20000 {
			label = "image-0";
			reg = <0x00020000 DT_SIZE_K(384)>;
		};

		/* secondary application image slot: 384KB */
		slot1_partition: partition@80000 {
			label = "image-1";
			reg = <0x00080000 DT_SIZE_K(384)>;
		};

		/* swap slot: 128KB */
		scratch_partition: partition@e0000 {
			label = "image-scratch";
			reg = <0x000e0000 DT_SIZE_K(128)>;
		};
	};
};

[github-actions]

Hi @thomasbouston! We appreciate you submitting your first issue for our open-source project. 🌟

Even though I'm a bot, I can assure you that the whole community is genuinely grateful for your time and effort. 🤖💙

[erwango]

Hi @thomasbouston,

Thanks for submitting this proposal. Don't hesitate to push a github Pull Request, since you already have a working partition.
This will be the fastest way to get the change integrated.