soc/integration: Add mixed lists to dts_property()

Allows a mix of integers and phandles in the list to support
generating gpio-controller references, interrupt-map
references and other more expressive DTS features.

litex/gen/common.py

@@ -49,20 +49,25 @@ def reverse_bytes(s):
 # DTS  ---------------------------------------------------------------------------------------------
 
 
-def dts_property(name: str, value: Union[int, str, List[int], List[str]] = None) -> str:
+def dts_property(name: str, value: Union[int, str, List[Union[int, str]], List[str]] = None) -> str:
     """Returns property 'name' formatted in Devicetree syntax
 
-    value can be None (default), int, str or a list of int or str.
+    value can be:
+      None (default)
+      int
+      str
+      list of str
+      list of int and str: in this case the str is expected to be a phandle.
     """
     if value is None:
         return f"{name};\n"
     elif isinstance(value, list):
-        if all(isinstance(v, int) for v in value):
+        if all(isinstance(v, str) for v in value):
+             of_value = ", ".join(f'"{v}"' for v in value)
+        elif all(isinstance(v, int) or (isinstance(v, str) and v.startswith("&")) for v in value):
             of_value = "<" + " ".join(f"{v}" for v in value) + ">"
-        elif all(isinstance(v, str) for v in value):
-            of_value = ", ".join(f'"{v}"' for v in value)
         else:
-            raise ValueError("All elements in the list must be of the same type (either all int or all str)")
+            raise ValueError(f"unsupported elements in {value}")
         return f"{name} = {of_value};\n"
     else:
         of_value = f'"{value}"' if isinstance(value, str) else f"<{value}>"