modules: openthread: add CMake error if Secure Storage has no backend

Secure Storage is used as PSA ITS in builds where TF-M is not enabled,
but it needs a storage backend where to physically save data.
If CONFIG_SECURE_STORAGE_ITS_STORE_IMPLEMENTATION_ZMS is used then its
"depends on" guarantee that there is a partition to use as physical
storage.
If CONFIG_SECURE_STORAGE_ITS_STORE_IMPLEMENTATION_SETTINGS is used instead
it might happen that CONFIG_SETTINGS_NONE gets selected resulting in
Settings not being able to store data anywhere.

This commit make the build to fail in this last case.

Signed-off-by: Valerio Setti <[email protected]>

Author: valeriosetti

modules/openthread/CMakeLists.txt

@@ -1,6 +1,12 @@
 if(CONFIG_OPENTHREAD)
 if(CONFIG_OPENTHREAD_SOURCES)
 
+if(CONFIG_OPENTHREAD_CRYPTO_PSA AND NOT CONFIG_BUILD_WITH_TFM)
+  if(CONFIG_SECURE_STORAGE_ITS_STORE_IMPLEMENTATION_SETTINGS AND CONFIG_SETTINGS_NONE)
+    message(FATAL_ERROR "No backend selected for Secure Storage.")
+  endif()
+endif()
+
 set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)
 
 macro(kconfig_to_ot_option kconfig_option ot_config description)