core/bankmachine: expose cmd_buffer_buffered param and small cleanup

litedram/core/bankmachine.py

@@ -43,13 +43,13 @@ class BankMachine(Module):
 
         # Command buffer
         cmd_buffer_layout = [("we", 1), ("adr", len(req.adr))]
-        cmd_buffer_lookahead = stream.SyncFIFO(cmd_buffer_layout, settings.cmd_buffer_depth)
+        cmd_buffer_lookahead = stream.SyncFIFO(
+            cmd_buffer_layout, settings.cmd_buffer_depth,
+            buffered=settings.cmd_buffer_buffered)
         cmd_buffer = stream.Buffer(cmd_buffer_layout) # 1 depth buffer to detect row change
         self.submodules += cmd_buffer_lookahead, cmd_buffer
         self.comb += [
-            req.connect(cmd_buffer_lookahead.sink, omit=["wdata_valid", "wdata_ready",
-                                                         "rdata_valid", "rdata_ready",
-                                                         "lock"]),
+            req.connect(cmd_buffer_lookahead.sink, keep={"valid", "ready", "we", "adr"}),
             cmd_buffer_lookahead.source.connect(cmd_buffer.sink),
             cmd_buffer.source.ready.eq(req.wdata_ready | req.rdata_valid),
             req.lock.eq(cmd_buffer_lookahead.source.valid | cmd_buffer.source.valid),
@@ -85,10 +85,9 @@ class BankMachine(Module):
 
         # Respect write-to-precharge specification
         precharge_time = 2 + settings.timing.tWR - 1 + 1
-        self.submodules.precharge_timer = WaitTimer(precharge_time)
-        self.comb += self.precharge_timer.wait.eq(~(cmd.valid &
-                                                    cmd.ready &
-                                                    cmd.is_write))
+        precharge_timer = WaitTimer(precharge_time)
+        self.submodules += precharge_timer
+        self.comb += precharge_timer.wait.eq(~(cmd.valid & cmd.ready & cmd.is_write))
 
         # Auto Precharge
         if settings.with_auto_precharge:
@@ -134,7 +133,7 @@ class BankMachine(Module):
         )
         fsm.act("PRECHARGE",
             # Note: we are presenting the column address, A10 is always low
-            If(self.precharge_timer.done,
+            If(precharge_timer.done,
                 cmd.valid.eq(1),
                 If(cmd.ready,
                     NextState("TRP")
@@ -146,7 +145,7 @@ class BankMachine(Module):
             track_close.eq(1)
         )
         fsm.act("AUTOPRECHARGE",
-            If(self.precharge_timer.done,
+            If(precharge_timer.done,
                 NextState("TRP")
             ),
             track_close.eq(1)
@@ -162,7 +161,7 @@ class BankMachine(Module):
             cmd.ras.eq(1)
         )
         fsm.act("REFRESH",
-            If(self.precharge_timer.done,
+            If(precharge_timer.done,
                 self.refresh_gnt.eq(1),
             ),
             track_close.eq(1),

litedram/core/controller.py

@@ -8,11 +8,14 @@ from litedram.core.multiplexer import *
 
 
 class ControllerSettings:
-    def __init__(self, cmd_buffer_depth=8, read_time=32, write_time=16,
+    def __init__(self,
+                 cmd_buffer_depth=8, cmd_buffer_buffered=False,
+                 read_time=32, write_time=16,
                  with_bandwidth=False,
                  with_refresh=True,
                  with_auto_precharge=True):
         self.cmd_buffer_depth = cmd_buffer_depth
+        self.cmd_buffer_buffered = cmd_buffer_buffered
         self.read_time = read_time
         self.write_time = write_time
         self.with_bandwidth = with_bandwidth