From e1137a3e5e7c08531065485519fced3f02c73e47 Mon Sep 17 00:00:00 2001
From: Gerard Marull-Paretas <gerard@teslabs.com>
Date: Wed, 11 Oct 2023 13:18:19 +0200
Subject: [PATCH] cmake: modules: dts: use devicetree stub file

By providing a devicetree stub file, we make sure some internal macros
required by devicetree.h are generated in devicetree_generated.h. This
makes sure that systems without devicetree can continue working without
extra ifdeffery.

Signed-off-by: Gerard Marull-Paretas <gerard@teslabs.com>
---
 boards/common/stub.dts                   | 14 ++++++++++++++
 cmake/modules/dts.cmake                  | 10 ++--------
 misc/generated/generated_header.template |  1 -
 3 files changed, 16 insertions(+), 9 deletions(-)
 create mode 100644 boards/common/stub.dts
 delete mode 100644 misc/generated/generated_header.template

diff --git a/boards/common/stub.dts b/boards/common/stub.dts
new file mode 100644
index 00000000000..ebb8b852a92
--- /dev/null
+++ b/boards/common/stub.dts
@@ -0,0 +1,14 @@
+/*
+ * Copyright (c) 2023 Nordic Semiconductor ASA
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/* empty stub file provided for systems not using devicetree */
+
+/dts-v1/;
+
+#include <skeleton.dtsi>
+
+/ {
+
+};
diff --git a/cmake/modules/dts.cmake b/cmake/modules/dts.cmake
index 8236195ff85..8cdd94cd574 100644
--- a/cmake/modules/dts.cmake
+++ b/cmake/modules/dts.cmake
@@ -125,10 +125,6 @@ set(DTS_CMAKE                   ${PROJECT_BINARY_DIR}/dts.cmake)
 # modules.
 set(VENDOR_PREFIXES             dts/bindings/vendor-prefixes.txt)
 
-#
-# Halt execution early if there is no devicetree.
-#
-
 # TODO: What to do about non-posix platforms where NOT CONFIG_HAS_DTS (xtensa)?
 # Drop support for NOT CONFIG_HAS_DTS perhaps?
 set_ifndef(DTS_SOURCE ${BOARD_DIR}/${BOARD}.dts)
@@ -138,10 +134,8 @@ if(EXISTS ${DTS_SOURCE})
     list(APPEND DTS_SOURCE ${BOARD_DIR}/${BOARD}_${BOARD_REVISION_STRING}.overlay)
   endif()
 else()
-  # If we don't have a devicetree after all, there's not much to do.
-  set(header_template ${ZEPHYR_BASE}/misc/generated/generated_header.template)
-  zephyr_file_copy(${header_template} ${DEVICETREE_GENERATED_H} ONLY_IF_DIFFERENT)
-  return()
+  # If we don't have a devicetree, provide an empty stub
+  set(DTS_SOURCE ${ZEPHYR_BASE}/boards/common/stub.dts)
 endif()
 
 #
diff --git a/misc/generated/generated_header.template b/misc/generated/generated_header.template
deleted file mode 100644
index 2b323cd20e1..00000000000
--- a/misc/generated/generated_header.template
+++ /dev/null
@@ -1 +0,0 @@
-/* WARNING. THIS FILE IS AUTO-GENERATED. DO NOT MODIFY! */