frontend/fifo: make sure FIFO is only used on LiteDRAMNativePort, expose writer/reader fifo depth, add separators and update copyrights.

litedram/frontend/fifo.py

@@ -1,14 +1,15 @@
-# This file is Copyright (c) 2018-2019 Florent Kermarrec <florent@enjoy-digital.fr>
+# This file is Copyright (c) 2018-2020 Florent Kermarrec <florent@enjoy-digital.fr>
+# This file is Copyright (c) 2020 Antmicro <www.antmicro.com>
 # License: BSD
 
-from litex.gen import *
+from migen import *
 
 from litex.soc.interconnect import stream
 
-from litedram.frontend import dma
 from litedram.common import LiteDRAMNativePort
-from litedram.frontend.axi import LiteDRAMAXIPort
+from litedram.frontend import dma
 
+# Helpers ------------------------------------------------------------------------------------------
 
 def _inc(signal, modulo):
     if modulo == 2**len(signal):
@@ -20,6 +21,7 @@ def _inc(signal, modulo):
             signal.eq(signal + 1)
         )
 
+# LiteDRAMFIFOCtrl ---------------------------------------------------------------------------------
 
 class _LiteDRAMFIFOCtrl(Module):
     def __init__(self, base, depth):
@@ -30,14 +32,14 @@ class _LiteDRAMFIFOCtrl(Module):
         # # #
 
         # To write buffer
-        self.writable = Signal()
+        self.writable      = Signal()
         self.write_address = Signal(max=depth)
 
         # From write buffer
         self.write = Signal()
 
         # To read buffer
-        self.readable = Signal()
+        self.readable     = Signal()
         self.read_address = Signal(max=depth)
 
         # From read buffer
@@ -67,37 +69,36 @@ class _LiteDRAMFIFOCtrl(Module):
             self.readable.eq(self.level > 0)
         ]
 
+# LiteDRAMFIFOWriter -------------------------------------------------------------------------------
 
 class _LiteDRAMFIFOWriter(Module):
-    def __init__(self, data_width, port, ctrl):
+    def __init__(self, data_width, port, ctrl, fifo_depth=32):
         self.sink = sink = stream.Endpoint([("data", data_width)])
 
         # # #
 
-        if isinstance(port, LiteDRAMNativePort):
-            write_ready = port.wdata.ready
-        elif isinstance(port, LiteDRAMAXIPort):
-            write_ready = port.w.ready
-        else:
-            raise NotImplementedError(port)
-
-        self.submodules.writer = writer = dma.LiteDRAMDMAWriter(port, fifo_depth=32)
+        self.submodules.writer = writer = dma.LiteDRAMDMAWriter(port, fifo_depth=fifo_depth)
         self.comb += [
             writer.sink.valid.eq(sink.valid & ctrl.writable),
             writer.sink.address.eq(ctrl.base + ctrl.write_address),
             writer.sink.data.eq(sink.data),
-            sink.ready.eq(writer.sink.valid & writer.sink.ready),
-            ctrl.write.eq(write_ready),
+            If(writer.sink.valid & writer.sink.ready,
+                sink.ready.eq(1)
+            ),
+            If(port.wdata.valid & port.wdata.ready,
+                ctrl.write.eq(1)
+            ),
         ]
 
+# LiteDRAMFIFOReader -------------------------------------------------------------------------------
 
 class _LiteDRAMFIFOReader(Module):
-    def __init__(self, data_width, port, ctrl):
+    def __init__(self, data_width, port, ctrl, fifo_depth=32):
         self.source = source = stream.Endpoint([("data", data_width)])
 
         # # #
 
-        self.submodules.reader = reader = dma.LiteDRAMDMAReader(port, fifo_depth=32)
+        self.submodules.reader = reader = dma.LiteDRAMDMAReader(port, fifo_depth=fifo_depth)
         self.comb += [
             reader.sink.valid.eq(ctrl.readable),
             reader.sink.address.eq(ctrl.base + ctrl.read_address),
@@ -107,18 +108,23 @@ class _LiteDRAMFIFOReader(Module):
         ]
         self.comb += reader.source.connect(source)
 
+# LiteDRAMFIFO -------------------------------------------------------------------------------------
 
 class LiteDRAMFIFO(Module):
     """LiteDRAM frontend that allows to use DRAM as a FIFO"""
-    def __init__(self, data_width, base, depth, write_port, read_port):
+    def __init__(self, data_width, base, depth, write_port, read_port,
+        writer_fifo_depth = 32,
+        reader_fifo_depth = 32):
+        assert isinstance(write_port, LiteDRAMNativePort)
+        assert isinstance(read_port,  LiteDRAMNativePort)
         self.sink   = stream.Endpoint([("data", data_width)])
         self.source = stream.Endpoint([("data", data_width)])
 
         # # #
 
         self.submodules.ctrl   = _LiteDRAMFIFOCtrl(base, depth)
-        self.submodules.writer = _LiteDRAMFIFOWriter(data_width, write_port, self.ctrl)
-        self.submodules.reader = _LiteDRAMFIFOReader(data_width, read_port, self.ctrl)
+        self.submodules.writer = _LiteDRAMFIFOWriter(data_width, write_port, self.ctrl, writer_fifo_depth)
+        self.submodules.reader = _LiteDRAMFIFOReader(data_width, read_port,  self.ctrl, reader_fifo_depth)
         self.comb += [
             self.sink.connect(self.writer.sink),
             self.reader.source.connect(self.source)