Rework resets

cocotbext/eth/reset.py

@@ -0,0 +1,66 @@
+"""
+
+Copyright (c) 2020 Alex Forencich
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+
+"""
+
+import cocotb
+from cocotb.triggers import RisingEdge, FallingEdge
+
+
+class Reset:
+    def _init_reset(self, reset_signal=None, active_high=True):
+        self._local_reset = False
+        self._ext_reset = False
+        self._reset_state = True
+
+        if reset_signal is not None:
+            cocotb.fork(self._run_reset(reset_signal, active_high))
+
+        self._update_reset()
+
+    def assert_reset(self, val=None):
+        if val is None:
+            self.assert_reset(True)
+            self.assert_reset(False)
+        else:
+            self._local_reset = val
+            self._update_reset()
+
+    def _update_reset(self):
+        new_state = self._local_reset or self._ext_reset
+        if self._reset_state != new_state:
+            self._reset_state = new_state
+            self._handle_reset(new_state)
+
+    def _handle_reset(self, state):
+        pass
+
+    async def _run_reset(self, reset_signal, active_high):
+        while True:
+            if bool(reset_signal.value):
+                await FallingEdge(reset_signal)
+                self._ext_reset = not active_high
+                self._update_reset()
+            else:
+                await RisingEdge(reset_signal)
+                self._ext_reset = active_high
+                self._update_reset()