[nrf noup] Patch chip_data_model.cmake

Make chip_data_model.cmake correctly determine CHIP_ROOT
constant if that is not defined in the application CMake.

Also, use Python3 selected by CMake.

Signed-off-by: Damian Krolik <damian.krolik@nordicsemi.no>

Author: Damian-Nordic

build/chip/chip_codegen.cmake

@@ -52,10 +52,10 @@ function(chip_codegen TARGET_NAME)
 
         # Python is expected to be in the path
         #
-        # find_package(Python3 REQUIRED)
+        find_package(Python3 REQUIRED)
         add_custom_command(
             OUTPUT ${OUT_NAMES}
-            COMMAND "${CHIP_ROOT}/scripts/codegen.py"
+            COMMAND ${Python3_EXECUTABLE} "${CHIP_ROOT}/scripts/codegen.py"
             ARGS "--generator" "${ARG_GENERATOR}"
                  "--output-dir" "${GEN_FOLDER}"
                  "--expected-outputs" "${GEN_FOLDER}/expected.outputs"

src/app/chip_data_model.cmake

@@ -16,6 +16,10 @@
 
 set(CHIP_APP_BASE_DIR ${CMAKE_CURRENT_LIST_DIR})
 
+if (NOT CHIP_ROOT)
+    get_filename_component(CHIP_ROOT ${CHIP_APP_BASE_DIR}/../.. REALPATH)
+endif()
+
 include("${CHIP_ROOT}/build/chip/chip_codegen.cmake")
 
 # Configure ${APP_TARGET} with source files associated with ${CLUSTER} cluster