validator: Add warning for properties with incompatible multiple types

While generally having multiple types for the same property name is
discouraged, there are some cases of this we're stuck with. In many cases
the type for a specific instance can be determined based on the property
length or the data (ASCII strings). In a few cases, there is no way to
tell. These cases have types of scalar, array, or matrix, and the possible
property length overlaps.

Signed-off-by: Rob Herring (Arm) <[email protected]>

dtschema/validator.py

@@ -479,10 +479,46 @@ def check_missing_property_types(self):
                 for id in val[0]['$id']:
                     print(f"{self.schemas[id]['$filename']}: {p}: missing type definition", file=sys.stderr)
 
+    def check_duplicate_property_types(self):
+        """
+        Check for properties with multiple types consisting of a mixture of
+        integer scalar, array or matrix. These cannot be decoded reliably.
+        """
+        for p, val in self.props.items():
+            # Exclude some known problematic properties
+            if p in ['dma-masters']:
+                continue
+
+            has_int = 0
+            has_array = 0
+            has_matrix = 0
+            for v in val:
+                if v['type'] is None:
+                    break
+                if re.match(r'u?int(8|16|32|64)$', v['type']):
+                    has_int += 1
+                elif re.match(r'u?int.+-array', v['type']):
+                    has_array += 1
+                elif re.match(r'u?int.+-matrix', v['type']):
+                    has_matrix += 1
+                    min_size = v['dim'][0][0] * v['dim'][1][0]
+                elif v['type'] == 'phandle-array':
+                    has_matrix += 1
+                    min_size = v['dim'][0][0] * v['dim'][1][0]
+
+            if not ((has_int and (has_array or (has_matrix and min_size == 1))) or
+                    (has_array and has_matrix)):
+                continue
+
+            for v in val:
+                for sch_id in v['$id']:
+                    print(f"{self.schemas[sch_id]['$filename']}: {p}: multiple incompatible types: {v['type']}", file=sys.stderr)
+
     def make_property_type_cache(self):
         self.props, self.pat_props = get_prop_types(self.schemas)
 
         self.check_missing_property_types()
+        self.check_duplicate_property_types()
 
         for val in self.props.values():
             for t in val: