[nrf noup] zephyr: Keep boot preference after reboot

Add a possibility to keep the boot preference value between device
resets.

Ref: NCSDK-35479

Signed-off-by: Tomasz Chyrowicz <[email protected]>

Author: tomchy

boot/bootutil/include/bootutil/boot_request.h

@@ -93,7 +93,10 @@ bool boot_request_detect_firmware_loader(void);
 int boot_request_init(void);
 
 /**
- * @brief Clear/drop all requests.
+ * @brief Clear boot requests.
+ *
+ * @details If the CONFIG_NRF_MCUBOOT_BOOT_REQUEST_PREFERENCE_KEEP option is
+ *          enabled, all requests, except the preferred slot requests, are cleared.
  *
  * @return 0 if successful, negative error code otherwise.
  */

boot/bootutil/zephyr/CMakeLists.txt

@@ -17,9 +17,15 @@ zephyr_library_sources(
   ../src/bootutil_public.c
     )
 if(CONFIG_NRF_MCUBOOT_BOOT_REQUEST)
+  zephyr_library_sources(
+    src/boot_request.c
+  )
   zephyr_library_sources_ifdef(CONFIG_NRF_MCUBOOT_BOOT_REQUEST_IMPL_RETENTION
     src/boot_request_retention.c
   )
+  zephyr_library_sources_ifdef(CONFIG_NRF_MCUBOOT_BOOT_REQUEST_IMPL_FLASH
+    src/boot_request_flash.c
+  )
 endif()
 zephyr_library_sources_ifdef(CONFIG_NCS_MCUBOOT_MANIFEST_UPDATES
   ../src/mcuboot_manifest.c