diff --git a/CMakeLists.txt b/CMakeLists.txt
index ead414c49..921457b89 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -34,6 +34,7 @@ option(OT_BUILTIN_MBEDTLS "Enable builtin mbedTLS" ON)
 
 include("${PROJECT_SOURCE_DIR}/etc/cmake/checks.cmake")
 include("${PROJECT_SOURCE_DIR}/etc/cmake/options.cmake")
+include("${PROJECT_SOURCE_DIR}/etc/cmake/functions.cmake")
 
 execute_process(
     COMMAND "${PROJECT_SOURCE_DIR}/third_party/nlbuild-autotools/repo/scripts/mkversion" "-b" "`cat .default-version`" "."
@@ -47,19 +48,6 @@ list(APPEND OT_PRIVATE_DEFINES
 
 set(OT_PLATFORM "none" CACHE STRING "Target platform chosen by the user at configure time")
 
-function(ot_get_platforms arg_platforms)
-    set(result "none")
-    set(platforms_dir "${PROJECT_SOURCE_DIR}/examples/platforms")
-    file(GLOB platforms RELATIVE "${platforms_dir}" "${platforms_dir}/*")
-    foreach(platform IN LISTS platforms)
-        if(IS_DIRECTORY "${platforms_dir}/${platform}")
-            list(APPEND result "${platform}")
-        endif()
-    endforeach()
-
-    set(${arg_platforms} "${result}" PARENT_SCOPE)
-endfunction()
-
 ot_get_platforms(OT_EXAMPLE_PLATFORMS)
 set_property(CACHE OT_PLATFORM PROPERTY STRINGS ${OT_EXAMPLE_PLATFORMS})
 if(NOT OT_PLATFORM IN_LIST OT_EXAMPLE_PLATFORMS)
diff --git a/etc/cmake/functions.cmake b/etc/cmake/functions.cmake
new file mode 100755
index 000000000..9caf9e82c
--- /dev/null
+++ b/etc/cmake/functions.cmake
@@ -0,0 +1,41 @@
+#
+#  Copyright (c) 2019, The OpenThread Authors.
+#  All rights reserved.
+#
+#  Redistribution and use in source and binary forms, with or without
+#  modification, are permitted provided that the following conditions are met:
+#  1. Redistributions of source code must retain the above copyright
+#     notice, this list of conditions and the following disclaimer.
+#  2. Redistributions in binary form must reproduce the above copyright
+#     notice, this list of conditions and the following disclaimer in the
+#     documentation and/or other materials provided with the distribution.
+#  3. Neither the name of the copyright holder nor the
+#     names of its contributors may be used to endorse or promote products
+#     derived from this software without specific prior written permission.
+#
+#  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+#  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+#  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+#  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+#  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+#  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+#  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+#  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+#  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+#  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+#  POSSIBILITY OF SUCH DAMAGE.
+#
+
+# Get a list of the available platforms and output as a list to the 'arg_platforms' argument
+function(ot_get_platforms arg_platforms)
+    set(result "none")
+    set(platforms_dir "${PROJECT_SOURCE_DIR}/examples/platforms")
+    file(GLOB platforms RELATIVE "${platforms_dir}" "${platforms_dir}/*")
+    foreach(platform IN LISTS platforms)
+        if(IS_DIRECTORY "${platforms_dir}/${platform}")
+            list(APPEND result "${platform}")
+        endif()
+    endforeach()
+
+    set(${arg_platforms} "${result}" PARENT_SCOPE)
+endfunction()