Add initial cocotb support to the sim flow

This adds a flow option called cocotb_module. Setting this enables
cocotb support. To begin with, cocotb support is only enabled for
the Icarus Verilog and ModelSim/QuestaSim tools.

edalize/flows/edaflow.py

@@ -311,7 +311,7 @@ def configure(self):
         # Write out execution file
         self.commands.write(os.path.join(self.work_root, "Makefile"))
 
-    def _run_tool(self, cmd, args=[], cwd=None, quiet=False):
+    def _run_tool(self, cmd, args=[], cwd=None, quiet=False, env={}):
         logger.debug("Running " + cmd)
         logger.debug("args  : " + " ".join(args))
 
@@ -325,6 +325,7 @@ def _run_tool(self, cmd, args=[], cwd=None, quiet=False):
                 stderr=self.stderr,
                 capture_output=capture_output,
                 check=True,
+                env={**os.environ, **env},
             )
         except FileNotFoundError:
             _s = "Command '{}' not found. Make sure it is in $PATH".format(cmd)

edalize/flows/sim.py

@@ -10,10 +10,47 @@ class Sim(Generic):
 
     argtypes = ["plusarg", "vlogdefine", "vlogparam"]
 
+    FLOW_OPTIONS = {
+        **Generic.FLOW_OPTIONS,
+        **{
+            "cocotb_module": {
+                "type": "str",
+                "desc": "Cocotb test python module. (Enables Cocotb simulations)",
+            },
+        },
+    }
+
+    def configure_tools(self, flow):
+        if self.flow_options.get("cocotb_module"):
+            tool = self.flow_options.get("tool")
+            cocotb_options = {
+                "icarus": (
+                    "vvp_options",
+                    [
+                        "-M",
+                        "`cocotb-config --lib-dir`",
+                        "-m",
+                        "`cocotb-config --lib-name vpi icarus`",
+                    ],
+                ),
+                "modelsim": (
+                    "vsim_options",
+                    ["-pli", "`cocotb-config --lib-name-path vpi questa`"],
+                ),
+            }
+            (opt, val) = cocotb_options[tool]
+            self.edam["tool_options"][tool][opt] = (
+                self.edam["tool_options"][tool].get(opt, []) + val
+            )
+
+        super().configure_tools(flow)
+
     def run(self, args=None):
         tool = self.flow_options.get("tool")
         run_tool = self.flow.get_node(tool).inst
 
         # Get run command from simulator
         (cmd, args, cwd) = run_tool.run()
-        self._run_tool(cmd, args=args, cwd=cwd)
+        cocotb_module = self.flow_options.get("cocotb_module")
+        env = {"MODULE": cocotb_module} if cocotb_module else {}
+        self._run_tool(cmd, args=args, cwd=cwd, env=env)