misoclib/com/uart: cleanup and add irq condition parameters

- reintroduce RX/TX split (ease comprehension)
- use FIFO wrapper function from Migen.
- add tx_irq_condition and rx_irq_condition

misoclib/com/uart/__init__.py

@@ -2,13 +2,13 @@ from migen.fhdl.std import *
 from migen.bank.description import *
 from migen.bank.eventmanager import *
 from migen.genlib.record import Record
-from migen.actorlib.fifo import SyncFIFO, AsyncFIFO
+from migen.actorlib.fifo import FIFO
 
 
 class UART(Module, AutoCSR):
     def __init__(self, phy,
-                 tx_fifo_depth=16,
-                 rx_fifo_depth=16,
+                 tx_fifo_depth=16, tx_irq_condition="empty",
+                 rx_fifo_depth=16, rx_irq_condition="non-empty",
                  phy_cd="sys"):
         self._rxtx = CSR(8)
         self._txfull = CSRStatus()
@@ -21,30 +21,37 @@ class UART(Module, AutoCSR):
 
         # # #
 
-        if phy_cd == "sys":
-            tx_fifo = SyncFIFO([("data", 8)], tx_fifo_depth)
-            rx_fifo = SyncFIFO([("data", 8)], rx_fifo_depth)
-            # Generate TX IRQ when tx_fifo becomes empty
-            tx_irq = tx_fifo.source.stb
-        else:
-            tx_fifo = ClockDomainsRenamer({"write": "sys", "read": phy_cd})(
-                AsyncFIFO([("data", 8)], tx_fifo_depth))
-            rx_fifo = ClockDomainsRenamer({"write": phy_cd, "read": "sys"})(
-                AsyncFIFO([("data", 8)], rx_fifo_depth))
-            # Generate TX IRQ when tx_fifo becomes non-full
-            tx_irq = ~tx_fifo.sink.ack
-        self.submodules += tx_fifo, rx_fifo
+        # TX
+        tx_fifo = FIFO([("data", 8)], tx_fifo_depth, source_cd=phy_cd)
+        self.submodules += tx_fifo
+
+        tx_irqs = {
+            "empty": tx_fifo.source.stb,
+            "non-full": ~tx_fifo.sink.ack
+        }
+
         self.comb += [
             tx_fifo.sink.stb.eq(self._rxtx.re),
             tx_fifo.sink.data.eq(self._rxtx.r),
             self._txfull.status.eq(~tx_fifo.sink.ack),
             Record.connect(tx_fifo.source, phy.sink),
-            self.ev.tx.trigger.eq(tx_irq),
+            self.ev.tx.trigger.eq(tx_irqs[tx_irq_condition])
+        ]
 
+
+        # RX
+        rx_fifo = FIFO([("data", 8)], rx_fifo_depth, sink_cd=phy_cd)
+        self.submodules += rx_fifo
+
+        rx_irqs = {
+            "non-empty": ~rx_fifo.source.stb,
+            "full": rx_fifo.sink.ack
+        }
+
+        self.comb += [
             Record.connect(phy.source, rx_fifo.sink),
             self._rxempty.status.eq(~rx_fifo.source.stb),
             self._rxtx.w.eq(rx_fifo.source.data),
             rx_fifo.source.ack.eq(self.ev.rx.clear),
-            # Generate RX IRQ when rx_fifo becomes non-empty
-            self.ev.rx.trigger.eq(~rx_fifo.source.stb),
+            self.ev.rx.trigger.eq(rx_irqs[rx_irq_condition])
         ]