feat: Add [chipflow.silicon.debug] section and a key for enabling heartbeat

Author: robtaylor

chipflow_lib/__init__.py

@@ -1,4 +1,4 @@
-import importlib
+import importlib.metadata
 import jsonschema
 import os
 import sys
@@ -87,6 +87,12 @@ def _ensure_chipflow_root():
                         },
                         "pads": {"$ref": "#/$defs/pin"},
                         "power": {"$ref": "#/$defs/pin"},
+                        "debug": {
+                            "type": "object",
+                            "properties": {
+                                "heartbeat": {"type": "boolean"}
+                            }
+                        }
                     },
                 },
             },

chipflow_lib/steps/silicon.py

@@ -31,16 +31,17 @@ def elaborate(self, platform: SiliconPlatform):
 
         platform.instantiate_ports(m)
 
-        # TODO: heartbeat led (to confirm clock/reset alive)
-        # heartbeat_ctr = Signal(23)
-        # m.d.sync += heartbeat_ctr.eq(heartbeat_ctr + 1)
-        # m.d.comb += platform.request("heartbeat").o.eq(heartbeat_ctr[-1])
+        # heartbeat led (to confirm clock/reset alive)
+        if ("config" in self._config["chipflow"]["silicon"] and
+           self._config["chipflow"]["silicon"]["debug"]["heartbeat"]):
+            heartbeat_ctr = Signal(23)
+            m.d.sync += heartbeat_ctr.eq(heartbeat_ctr + 1)
+            m.d.comb += platform.request("heartbeat").o.eq(heartbeat_ctr[-1])
 
         top, interfaces = top_interfaces(self._config)
         for n, t in top.items():
             setattr(m.submodules, n, t)
 
-        # TODO: heartbeat
         return m