cmake: support list mode in Zephyr-sdk module package

Introduce list mode in Zephyr-sdk module package.

The list mode allows to list all Zephyr SDK's found in the system
without loading any of them.

Signature of the list mode is:
> find_package(Zephyr-sdk COMPONENTS LIST)

Will print valid Zephyr SDKs and their path, as well as defining the
following corresponding CMake lists:
- Zephyr-sdk      : List of Zephyr SDKs' version
- Zephyr-sdk_DIRS : List of Directories with a valid Zephyr SDK.
Each entry in Zephyr-sdk corresponds to the same entry index in the
Zephyr-sdk_DIRS list.

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

cmake/modules/FindZephyr-sdk.cmake

@@ -4,23 +4,39 @@
 
 # FindZephyr-sdk module for supporting module search mode of Zephyr SDK.
 #
-# Its purpose is to allow the find_package basic signature mode to lookup Zephyr
+# It is possible to control the behavior of the Zephyr-SDK package using
-# SDK and based on user / environment settings of selected toolchain decide if
+# COMPONENTS.
-# the Zephyr SDK CMake package should be loaded.
+# The Zephyr-SDK package supports the components:
+# - LOAD: Load a Zephyr-SDK. This is the default behavior if no COMPONENTS is specified.
+#         Its purpose is to allow the find_package basic signature mode to lookup Zephyr
+#         SDK and based on user / environment settings of selected toolchain decide if
+#         the Zephyr SDK CMake package should be loaded.
 #
-# It extends the Zephyr-sdk CMake package by providing more flexibility in when
+#         It extends the Zephyr-sdk CMake package by providing more flexibility in when
-# the Zephyr SDK is loaded and loads additional host tools from the Zephyr SDK.
+#         the Zephyr SDK is loaded and loads additional host tools from the Zephyr SDK.
 #
-# The module defines the following variables:
+#         The module defines the following variables when used in normal search and load mode:
+#         'ZEPHYR_SDK_INSTALL_DIR'
+#         Install location of the Zephyr SDK
 #
-# 'ZEPHYR_SDK_INSTALL_DIR'
+#         'ZEPHYR_TOOLCHAIN_VARIANT'
-# Install location of the Zephyr SDK
+#         Zephyr toolchain variant to use if not defined already.
 #
-# 'ZEPHYR_TOOLCHAIN_VARIANT'
+#         'Zephyr-sdk_FOUND'
-# Zephyr toolchain variant to use if not defined already.
+#         True if the Zephyr SDK was found.
+
+# - LIST: Will list all available Zephyr SDKs found in the system but not load
+#         any Sdk. This can be used to fetch available Zephyr-SDKs before doing
+#         an actual load.
+#         LIST component will define the following lists:
+#         - Zephyr-sdk      : Version of a Zephyr-SDK
+#         - Zephyr-sdk_DIRS : Install dir of the Zephyr-SDK
+#         Each entry in Zephyr-SDK has a corresponding entry in Zephyr-SDK_DIRS.
+#         For example:
+#         index:  Zephyr-sdk:    Zephyr-sdk_DIRS:
+#         0       0.15.0         /opt/zephyr-sdk-0.15.0
+#         1       0.16.0         /home/<user>/zephyr-sdk-0.16.0
 #
-# 'Zephyr-sdk_FOUND'
-# True if the Zephyr SDK was found.
 
 include(extensions)
 
@@ -29,6 +45,10 @@ zephyr_get(ZEPHYR_TOOLCHAIN_VARIANT)
 
 zephyr_get(ZEPHYR_SDK_INSTALL_DIR)
 
+if("${Zephyr-sdk_FIND_COMPONENTS}" STREQUAL "")
+  set(Zephyr-sdk_FIND_COMPONENTS LOAD)
+endif()
+
 # Load Zephyr SDK Toolchain.
 # There are three scenarios where Zephyr SDK should be looked up:
 # 1) Zephyr specified as toolchain (ZEPHYR_SDK_INSTALL_DIR still used if defined)
@@ -52,7 +72,7 @@ if(("zephyr" STREQUAL ${ZEPHYR_TOOLCHAIN_VARIANT}) OR
   SET(CMAKE_FIND_PACKAGE_SORT_DIRECTION DEC)
   SET(CMAKE_FIND_PACKAGE_SORT_ORDER NATURAL)
 
-  if(DEFINED ZEPHYR_SDK_INSTALL_DIR)
+  if(DEFINED ZEPHYR_SDK_INSTALL_DIR AND LOAD IN_LIST Zephyr-sdk_FIND_COMPONENTS)
     # The Zephyr SDK will automatically set the toolchain variant.
     # To support Zephyr SDK tools (DTC, and other tools) with 3rd party toolchains
     # then we keep track of current toolchain variant.
@@ -80,36 +100,53 @@ if(("zephyr" STREQUAL ${ZEPHYR_TOOLCHAIN_VARIANT}) OR
     find_package(Zephyr-sdk 0.0.0 EXACT QUIET CONFIG PATHS ${zephyr_sdk_search_paths})
 
     # Remove duplicate entries and sort naturally in descending order.
-    set(zephyr_sdk_found_versions ${Zephyr-sdk_CONSIDERED_VERSIONS})
+    foreach(version config IN ZIP_LISTS Zephyr-sdk_CONSIDERED_VERSIONS Zephyr-sdk_CONSIDERED_CONFIGS)
-    set(zephyr_sdk_found_configs ${Zephyr-sdk_CONSIDERED_CONFIGS})
+      if(NOT DEFINED Zephyr-sdk-${version}_DIR)
+        set(Zephyr-sdk-${version}_DIR ${config})
+      endif()
+    endforeach()
 
     list(REMOVE_DUPLICATES Zephyr-sdk_CONSIDERED_VERSIONS)
     list(SORT Zephyr-sdk_CONSIDERED_VERSIONS COMPARE NATURAL ORDER DESCENDING)
 
-    # Loop over each found Zepher SDK version until one is found that is compatible.
+    if(LIST IN_LIST Zephyr-sdk_FIND_COMPONENTS)
-    foreach(zephyr_sdk_candidate ${Zephyr-sdk_CONSIDERED_VERSIONS})
+      set(Zephyr-sdk)
-      if("${zephyr_sdk_candidate}" VERSION_GREATER_EQUAL "${Zephyr-sdk_FIND_VERSION}")
+      set(Zephyr-sdk_DIRS)
-        # Find the path for the current version being checked and get the directory
+      # Only list the Zephyr SDKs installed in the system.
-        # of the Zephyr SDK so it can be checked.
+      foreach(version ${Zephyr-sdk_CONSIDERED_VERSIONS})
-        list(FIND zephyr_sdk_found_versions ${zephyr_sdk_candidate} zephyr_sdk_current_index)
+        cmake_path(GET Zephyr-sdk-${version}_DIR PARENT_PATH dir)
-        list(GET zephyr_sdk_found_configs ${zephyr_sdk_current_index} zephyr_sdk_current_check_path)
+        cmake_path(GET dir PARENT_PATH dir)
-        get_filename_component(zephyr_sdk_current_check_path ${zephyr_sdk_current_check_path} DIRECTORY)
+        list(APPEND Zephyr-sdk ${version})
-
+        list(APPEND Zephyr-sdk_DIRS ${dir})
-        # Then see if this version is compatible.
+        if (NOT Zephyr-sdk_FIND_QUIETLY)
-        find_package(Zephyr-sdk ${Zephyr-sdk_FIND_VERSION} QUIET CONFIG PATHS ${zephyr_sdk_current_check_path} NO_DEFAULT_PATH)
+          message(STATUS "Zephyr-sdk, version=${version}, dir=${dir}")
-
-        if (${Zephyr-sdk_FOUND})
-          # A compatible version of the Zephyr SDK has been found which is the highest
-          # supported version, exit.
-          break()
         endif()
-      endif()
+      endforeach()
-    endforeach()
+    else()
+      # Loop over each found Zepher SDK version until one is found that is compatible.
+      foreach(zephyr_sdk_candidate ${Zephyr-sdk_CONSIDERED_VERSIONS})
+        if("${zephyr_sdk_candidate}" VERSION_GREATER_EQUAL "${Zephyr-sdk_FIND_VERSION}")
+          # Find the path for the current version being checked and get the directory
+          # of the Zephyr SDK so it can be checked.
+          cmake_path(GET Zephyr-sdk-${zephyr_sdk_candidate}_DIR PARENT_PATH zephyr_sdk_current_check_path)
+          cmake_path(GET zephyr_sdk_current_check_path PARENT_PATH zephyr_sdk_current_check_path)
 
-    if (NOT ${Zephyr-sdk_FOUND})
+          # Then see if this version is compatible.
-      # This means no compatible Zephyr SDK versions were found, set the version
+          find_package(Zephyr-sdk ${Zephyr-sdk_FIND_VERSION} QUIET CONFIG PATHS ${zephyr_sdk_current_check_path} NO_DEFAULT_PATH)
-      # back to the minimum version so that it is displayed in the error text.
+
-      find_package(Zephyr-sdk ${Zephyr-sdk_FIND_VERSION} REQUIRED CONFIG PATHS ${zephyr_sdk_search_paths})
+          if (${Zephyr-sdk_FOUND})
+            # A compatible version of the Zephyr SDK has been found which is the highest
+            # supported version, exit.
+            break()
+          endif()
+        endif()
+      endforeach()
+
+      if (NOT ${Zephyr-sdk_FOUND})
+        # This means no compatible Zephyr SDK versions were found, set the version
+        # back to the minimum version so that it is displayed in the error text.
+        find_package(Zephyr-sdk ${Zephyr-sdk_FIND_VERSION} REQUIRED CONFIG PATHS ${zephyr_sdk_search_paths})
+      endif()
     endif()
   endif()
 
@@ -124,15 +161,17 @@ set(zephyr_sdk_found_configs)
 set(zephyr_sdk_current_index)
 set(zephyr_sdk_current_check_path)
 
-if(DEFINED ZEPHYR_SDK_INSTALL_DIR)
+if(LOAD IN_LIST Zephyr-sdk_FIND_COMPONENTS)
-  # Cache the Zephyr SDK install dir.
+  if(DEFINED ZEPHYR_SDK_INSTALL_DIR)
-  set(ZEPHYR_SDK_INSTALL_DIR ${ZEPHYR_SDK_INSTALL_DIR} CACHE PATH "Zephyr SDK install directory")
+    # Cache the Zephyr SDK install dir.
-endif()
+    set(ZEPHYR_SDK_INSTALL_DIR ${ZEPHYR_SDK_INSTALL_DIR} CACHE PATH "Zephyr SDK install directory")
+  endif()
 
-if(Zephyr-sdk_FOUND)
+  if(Zephyr-sdk_FOUND)
-  include(${ZEPHYR_SDK_INSTALL_DIR}/cmake/zephyr/host-tools.cmake)
+    include(${ZEPHYR_SDK_INSTALL_DIR}/cmake/zephyr/host-tools.cmake)
 
-  if (NOT Zephyr-sdk_FIND_QUIETLY)
+    if (NOT Zephyr-sdk_FIND_QUIETLY)
-    message(STATUS "Found host-tools: zephyr ${SDK_VERSION} (${ZEPHYR_SDK_INSTALL_DIR})")
+      message(STATUS "Found host-tools: zephyr ${SDK_VERSION} (${ZEPHYR_SDK_INSTALL_DIR})")
+    endif()
   endif()
 endif()