[PATCH v1 07/10] kconfig-checker: Introduce overlays schema

["Ahmed S. Darwish" <darwi@linutronix.de>]

Keep `expected` and `severity` as optional for every rule.

This allows overlay files to be partial by design: they may override only
selected fields of an existing rule.

Signed-off-by: Ahmed S. Darwish <darwi@linutronix.de>
---
 tools/kconfig-checker/schemas/base.yml    |  4 ++--
 tools/kconfig-checker/schemas/overlay.yml | 28 +++++++++++++++++++++++
 2 files changed, 30 insertions(+), 2 deletions(-)
 create mode 100644 tools/kconfig-checker/schemas/overlay.yml

diff --git a/tools/kconfig-checker/schemas/base.yml b/tools/kconfig-checker/schemas/base.yml
index 1cc19752ebd6..6217eaba3e41 100644
--- a/tools/kconfig-checker/schemas/base.yml
+++ b/tools/kconfig-checker/schemas/base.yml
@@ -53,8 +53,8 @@ properties:
         #   y        option is expected to be enabled (built-in or module).
         #   n        option is expected to be disabled or unset.
         #   allowed  option is permitted and must not be reported as a violation.
-        #            This is used to exempt a specific symbol from a broader
-        #            `name_pattern` rule  with `expected: n`.
+        #            This is to be used either by overlays, or to exempt a specific
+        #            symbol from a broader `name_pattern` rule  with `expected: n`.
         #
         expected:
           type: string
diff --git a/tools/kconfig-checker/schemas/overlay.yml b/tools/kconfig-checker/schemas/overlay.yml
new file mode 100644
index 000000000000..4ac9a364a344
--- /dev/null
+++ b/tools/kconfig-checker/schemas/overlay.yml
@@ -0,0 +1,28 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+"$schema": "https://json-schema.org/draft-07/schema#"
+
+title: Schema for kconfig-checker overlay files
+
+#
+# Full rule files require 'expected' and 'severity' for every rule.
+# Overlay files are partial by design: they may override only selected
+# fields of an existing rule, so such fields are not required here.
+#
+# For example, preempt_rt.yml:
+#
+# rules:
+#  - name: CONFIG_DRM
+#    expected: n
+#    severity: info
+#    docs_hint: config
+#
+# and a custom-overlay.yml:
+#
+# rules:
+#  - name: CONFIG_DRM
+#    expected: allow
+#
+
+allOf:
+  - $ref: "base.yml"
-- 
2.56.0