edtlib: validate compatible properties

Error out on compatible properties with invalid values. The regular
expression used to validate them matches what's used in dt-schema.

Signed-off-by: Martí Bolívar <marti.bolivar@nordicsemi.no>

scripts/dts/python-devicetree/src/devicetree/edtlib.py

@@ -475,6 +475,30 @@ class EDT:
                         'in lowercase: ' +
                         ', '.join(repr(x) for x in spec.enum))
 
+        # Validate the contents of compatible properties.
+        # The regular expression comes from dt-schema.
+        compat_re = r'^[a-zA-Z][a-zA-Z0-9,+\-._]+$'
+        for node in self.nodes:
+            if 'compatible' not in node.props:
+                continue
+
+            compatibles = node.props['compatible'].val
+
+            # _check() runs after _init_compat2binding() has called
+            # _dt_compats(), which already converted every compatible
+            # property to a list of strings. So we know 'compatibles'
+            # is a list, but add an assert for future-proofing.
+            assert isinstance(compatibles, list)
+
+            for compat in compatibles:
+                # This is also just for future-proofing.
+                assert isinstance(compat, str)
+
+                if not re.match(compat_re, compat):
+                    _err(f"node '{node.path}' compatible '{compat}' "
+                         'must match this regular expression: '
+                         f"'{compat_re}'")
+
 class Node:
     """
     Represents a devicetree node, augmented with information from bindings, and

scripts/dts/python-devicetree/tests/test_edtlib.py

@@ -498,6 +498,24 @@ def test_slice_errs(tmp_path):
                  dts_file,
                  f"'ranges' property in <Node /sub-1 in '{dts_file}'> has length 8, which is not evenly divisible by 24 (= 4*(<#address-cells> (= 2) + <#address-cells for parent> (= 1) + <#size-cells> (= 3))). Note that #*-cells properties come either from the parent node or from the controller (in the case of 'interrupts').")
 
+def test_bad_compatible(tmp_path):
+    # An invalid compatible should cause an error, even on a node with
+    # no binding.
+
+    dts_file = tmp_path / "error.dts"
+
+    verify_error("""
+/dts-v1/;
+
+/ {
+	foo {
+		compatible = "no, whitespace";
+	};
+};
+""",
+                 dts_file,
+                 r"node '/foo' compatible 'no, whitespace' must match this regular expression: '^[a-zA-Z][a-zA-Z0-9,+\-._]+$'")
+
 def verify_error(dts, dts_file, expected_err):
     # Verifies that parsing a file 'dts_file' with the contents 'dts'
     # (a string) raises an EDTError with the message 'expected_err'.