zephyr: zmake: add board-specific DTS overlays

Allow board-specific DTS overlays to be placed at
zephyr/dts/board-overlays/${BOARD}.dts in any module.  Zmake will find
the file and append it to the DTC_OVERLAY_FILE list when discovered.

BUG=b:179491802
BRANCH=none
TEST=provided unit test passes

Signed-off-by: Jack Rosenthal <jrosenth@chromium.org>
Change-Id: I53d4a04b6056689696b4615b5998937dbcf801c4
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2678795
Reviewed-by: Simon Glass <sjg@chromium.org>

10 files changed, 150 insertions, 3 deletions

diff --git a/zephyr/dts/board-overlays/native_posix.dts b/zephyr/dts/board-overlays/native_posix.dts
new file mode 100644
index 0000000000..b8faf65842
--- /dev/null
+++ b/zephyr/dts/board-overlays/native_posix.dts
@@ -0,0 +1,6 @@
+/* Copyright 2021 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/* TODO(sjg): add things */
diff --git a/zephyr/test/i2c/boards/native_posix.overlay b/zephyr/test/i2c/overlay.dts
index ec534a1b88..ec534a1b88 100644
--- a/zephyr/test/i2c/boards/native_posix.overlay
+++ b/zephyr/test/i2c/overlay.dts
diff --git a/zephyr/test/i2c/zmake.yaml b/zephyr/test/i2c/zmake.yaml
index 8269f3557e..54e80db400 100644
--- a/zephyr/test/i2c/zmake.yaml
+++ b/zephyr/test/i2c/zmake.yaml
@@ -8,3 +8,5 @@ supported-zephyr-versions:
 toolchain: llvm
 output-type: elf
 is-test: true
+dts-overlays:
+  - overlay.dts
diff --git a/zephyr/test/i2c_dts/boards/native_posix.overlay b/zephyr/test/i2c_dts/overlay.dts
index ec534a1b88..ec534a1b88 100644
--- a/zephyr/test/i2c_dts/boards/native_posix.overlay
+++ b/zephyr/test/i2c_dts/overlay.dts
diff --git a/zephyr/test/i2c_dts/zmake.yaml b/zephyr/test/i2c_dts/zmake.yaml
index d0d40dd473..664e8d9177 100644
--- a/zephyr/test/i2c_dts/zmake.yaml
+++ b/zephyr/test/i2c_dts/zmake.yaml
@@ -8,3 +8,5 @@ supported-zephyr-versions:
 output-type: elf
 toolchain: llvm
 is-test: true
+dts-overlays:
+  - overlay.dts
diff --git a/zephyr/test/system/boards/native_posix.overlay b/zephyr/test/system/overlay.dts
index 49698a7553..49698a7553 100644
--- a/zephyr/test/system/boards/native_posix.overlay
+++ b/zephyr/test/system/overlay.dts
diff --git a/zephyr/test/system/zmake.yaml b/zephyr/test/system/zmake.yaml
index d0d40dd473..664e8d9177 100644
--- a/zephyr/test/system/zmake.yaml
+++ b/zephyr/test/system/zmake.yaml
@@ -8,3 +8,5 @@ supported-zephyr-versions:
 output-type: elf
 toolchain: llvm
 is-test: true
+dts-overlays:
+  - overlay.dts
diff --git a/zephyr/zmake/tests/test_project.py b/zephyr/zmake/tests/test_project.py
new file mode 100644
index 0000000000..a47407e95e
--- /dev/null
+++ b/zephyr/zmake/tests/test_project.py
@@ -0,0 +1,82 @@
+# Copyright 2021 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import hypothesis
+import hypothesis.strategies as st
+import pathlib
+import string
+import tempfile
+
+import zmake.project
+
+
+board_names = st.text(alphabet=set(string.ascii_lowercase) | {'_'},
+                      min_size=1)
+sets_of_board_names = st.lists(st.lists(board_names, unique=True))
+
+
+class TemporaryProject(tempfile.TemporaryDirectory):
+    """A temporary project wrapper.
+
+    Args:
+        config: The config dictionary to be used with the project.
+    """
+    def __init__(self, config):
+        self.config = config
+        super().__init__()
+
+    def __enter__(self):
+        project_path = pathlib.Path(super().__enter__())
+        return zmake.project.Project(project_path, config_dict=self.config)
+
+
+@hypothesis.given(sets_of_board_names)
+@hypothesis.settings(deadline=1000)
+def test_find_dts_overlays(modules):
+    """Test the functionality of find_dts_overlays with multiple
+    modules, each with sets of board names."""
+
+    # Recursive function to wind up all the temporary directories and
+    # call the actual test.
+    def setup_modules_and_dispatch(modules, test_fn, module_list=()):
+        if modules:
+            boards = modules[0]
+            with tempfile.TemporaryDirectory() as modpath:
+                modpath = pathlib.Path(modpath)
+                for board in boards:
+                    dts_path = zmake.project.module_dts_overlay_name(
+                        modpath, board)
+                    dts_path.parent.mkdir(parents=True, exist_ok=True)
+                    dts_path.touch()
+                setup_modules_and_dispatch(
+                    modules[1:], test_fn, module_list=module_list + (modpath,))
+        else:
+            test_fn(module_list)
+
+    # The actual test case, once temp modules have been setup.
+    def testcase(module_paths):
+        # Maps board_name→overlay_files
+        board_file_mapping = {}
+        for modpath, board_list in zip(module_paths, modules):
+            for board in board_list:
+                file_name = zmake.project.module_dts_overlay_name(
+                    modpath, board)
+                files = board_file_mapping.get(board, set())
+                board_file_mapping[board] = files | {file_name}
+
+        for board, expected_dts_files in board_file_mapping.items():
+            with TemporaryProject(
+                {'board': board,
+                 'toolchain': 'foo',
+                 'output-type': 'elf',
+                 'supported-zephyr-versions': ['v2.4']}) as project:
+                config = project.find_dts_overlays(
+                    dict(enumerate(module_paths)))
+
+                actual_dts_files = set(
+                    config.cmake_defs.get('DTC_OVERLAY_FILE', '').split(';'))
+
+                assert actual_dts_files == set(map(str, expected_dts_files))
+
+    setup_modules_and_dispatch(modules, testcase)
diff --git a/zephyr/zmake/zmake/project.py b/zephyr/zmake/zmake/project.py
index db8e5a2e17..f851c00980 100644
--- a/zephyr/zmake/zmake/project.py
+++ b/zephyr/zmake/zmake/project.py
@@ -11,6 +11,20 @@ import zmake.output_packers as packers
 import zmake.util as util
 
 
+def module_dts_overlay_name(modpath, board_name):
+    """Given a board name, return the expected DTS overlay path.
+
+    Args:
+        modpath: the module path as a pathlib.Path object
+        board_name: the name of the board
+
+    Returns:
+        A pathlib.Path object to the expected overlay path.
+    """
+    return modpath / 'zephyr' / 'dts' / 'board-overlays' / '{}.dts'.format(
+        board_name)
+
+
 class ProjectConfig:
     """An object wrapping zmake.yaml."""
     validator = jsonschema.Draft7Validator
@@ -41,6 +55,12 @@ class ProjectConfig:
             'is-test': {
                 'type': 'boolean',
             },
+            'dts-overlays': {
+                'type': 'array',
+                'items': {
+                    'type': 'string',
+                },
+            },
         },
     }
 
@@ -70,13 +90,19 @@ class ProjectConfig:
     def is_test(self):
         return self.config_dict.get('is-test', False)
 
+    @property
+    def dts_overlays(self):
+        return self.config_dict.get('dts-overlays', [])
+
 
 class Project:
     """An object encapsulating a project directory."""
-    def __init__(self, project_dir):
+    def __init__(self, project_dir, config_dict=None):
         self.project_dir = project_dir.resolve()
-        with open(self.project_dir / 'zmake.yaml') as f:
-            self.config = ProjectConfig(yaml.safe_load(f))
+        if not config_dict:
+            with open(self.project_dir / 'zmake.yaml') as f:
+                config_dict = yaml.safe_load(f)
+        self.config = ProjectConfig(config_dict)
         self.packer = self.config.output_packer(self)
 
     def iter_builds(self):
@@ -94,3 +120,27 @@ class Project:
             conf |= build_config.BuildConfig(kconfig_files=[prj_conf])
         for build_name, packer_config in self.packer.configs():
             yield build_name, conf | packer_config
+
+    def find_dts_overlays(self, modules):
+        """Find appropriate dts overlays from registered modules.
+
+        Args:
+            modules: A dictionary of module names mapping to paths.
+
+        Returns:
+            A BuildConfig with relevant configurations to enable the
+            found DTS overlay files.
+        """
+        overlays = []
+        for module_path in modules.values():
+            dts_path = module_dts_overlay_name(module_path, self.config.board)
+            if dts_path.is_file():
+                overlays.append(dts_path.resolve())
+
+        overlays.extend(self.project_dir / f for f in self.config.dts_overlays)
+
+        if overlays:
+            return build_config.BuildConfig(
+                cmake_defs={'DTC_OVERLAY_FILE': ';'.join(map(str, overlays))})
+        else:
+            return build_config.BuildConfig()
diff --git a/zephyr/zmake/zmake/zmake.py b/zephyr/zmake/zmake/zmake.py
index 8021351a34..2bbe818007 100644
--- a/zephyr/zmake/zmake/zmake.py
+++ b/zephyr/zmake/zmake/zmake.py
@@ -102,6 +102,8 @@ class Zmake:
         module_config = zmake.modules.setup_module_symlinks(
             build_dir / 'modules', module_paths)
 
+        dts_overlay_config = project.find_dts_overlays(module_paths)
+
         if not toolchain:
             toolchain = project.config.toolchain
 
@@ -120,6 +122,7 @@ class Zmake:
             config = (base_config
                       | toolchain_config
                       | module_config
+                      | dts_overlay_config
                       | build_config)
             output_dir = build_dir / 'build-{}'.format(build_name)
             kconfig_file = build_dir / 'kconfig-{}.conf'.format(build_name)