cmake: implement build infrastructure for supporting SCA tools.

Static code analyser (SCA) tools are important in software development.

CMake offers built-in support for some tools, such as cppcheck and
clang-tidy.

Other tools, such as sparse, are not directly supported.

This commit provides a uniform way for users to specify a supported
SCA using `ZEPHYR_SCA_VARIANT=<tool>` which is consistent with how
toolchains are specified.
ZEPHYR_SCA_VARIANT can be set using `-D` or in environment.

Support for an SCA tool is done in `cmake/sca/<tool>/sca.cmake`.
SCA_ROOT can be used to specify additional search paths when looking up
implementation for a tool. SCA_ROOT can also be specified in
`zephyr/module.yml` as setting. This makes it possible to provide SCA
tool implementation as part of a Zephyr module.

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>

cmake/modules/FindScaTools.cmake

@@ -0,0 +1,31 @@
+# SPDX-License-Identifier: Apache-2.0
+#
+# Copyright (c) 2022, Nordic Semiconductor ASA
+
+# 'SCA_ROOT' is a prioritized list of directories where SCA tools may
+# be found. It always includes ${ZEPHYR_BASE} at the lowest priority.
+list(APPEND SCA_ROOT ${ZEPHYR_BASE})
+
+zephyr_get(ZEPHYR_SCA_VARIANT)
+
+if(ScaTools_FIND_REQUIRED AND NOT DEFINED ZEPHYR_SCA_VARIANT)
+  message(FATAL_ERROR "ScaTools required but 'ZEPHYR_SCA_VARIANT' is not set. "
+                      "Please set 'ZEPHYR_SCA_VARIANT' to desired tool."
+  )
+endif()
+
+if(NOT DEFINED ZEPHYR_SCA_VARIANT)
+  return()
+endif()
+
+foreach(root ${SCA_ROOT})
+  if(EXISTS ${root}/cmake/sca/${ZEPHYR_SCA_VARIANT}/sca.cmake)
+    include(${root}/cmake/sca/${ZEPHYR_SCA_VARIANT}/sca.cmake)
+    return()
+  endif()
+endforeach()
+
+message(FATAL_ERROR "ZEPHYR_SCA_VARIANT set to '${ZEPHYR_SCA_VARIANT}' but no "
+                    "implementation for '${ZEPHYR_SCA_VARIANT}' found. "
+                    "SCA_ROOTs searched: ${SCA_ROOT}"
+)

cmake/modules/kernel.cmake

@@ -23,6 +23,7 @@
 include_guard(GLOBAL)
 
 find_package(TargetTools)
+find_package(ScaTools)
 
 # As this module is not intended for direct loading, but should be loaded through
 # find_package(Zephyr) then it won't be loading any Zephyr CMake modules by itself.

cmake/modules/root.cmake

@@ -33,6 +33,9 @@ zephyr_file(APPLICATION_ROOT SOC_ROOT)
 # Convert paths to absolute, relative from APPLICATION_SOURCE_DIR
 zephyr_file(APPLICATION_ROOT ARCH_ROOT)
 
+# Convert paths to absolute, relative from APPLICATION_SOURCE_DIR
+zephyr_file(APPLICATION_ROOT SCA_ROOT)
+
 if(unittest IN_LIST Zephyr_FIND_COMPONENTS)
   # Zephyr used in unittest mode, use dedicated unittest root.
   set(BOARD_ROOT ${ZEPHYR_BASE}/subsys/testsuite)

scripts/zephyr_module.py

@@ -81,6 +81,9 @@ mapping:
           module_ext_root:
             required: false
             type: str
+          sca_root:
+            required: false
+            type: str
   tests:
     required: false
     type: seq
@@ -219,7 +222,7 @@ def process_settings(module, meta):
     out_text = ""
 
     if build_settings is not None:
-        for root in ['board', 'dts', 'soc', 'arch', 'module_ext']:
+        for root in ['board', 'dts', 'soc', 'arch', 'module_ext', 'sca']:
             setting = build_settings.get(root+'_root', None)
             if setting is not None:
                 root_path = PurePath(module) / setting