modules: mcuboot: Add Kconfig option for BOOT_MAX_ALIGN

Add a configuration option to override the default BOOT_MAX_ALIGN value in
mcuboot. It defaults to the chosen flash's write block size to make it
backwards compatible.

This can be used when image slots are on different flash devices.

Signed-off-by: Pieter De Gendt <pieter.degendt@basalte.be>

Author: pdgendt

modules/Kconfig.mcuboot

@@ -430,4 +430,14 @@ config MCUBOOT_BOOTUTIL_LIB_FOR_DIRECT_XIP
 	  when bootloader is in DirectXIP-revert mode.
 endif
 
+DT_CHOSEN_ZEPHYR_FLASH := zephyr,flash
+
+config MCUBOOT_BOOT_MAX_ALIGN
+	int "Override programmable flash block alignment"
+	default $(dt_node_int_prop_int,$(DT_CHOSEN_ZEPHYR_FLASH),write-block-size)
+	help
+	  Allow to override the programmable flash block alignment size.
+	  By default it's set to the maximum of the write block size of
+	  the chosen zephyr,flash node and 8.
+
 endif # MCUBOOT_BOOTUTIL_LIB