s6ddrphy: add support for differential dqs and optional cs_n

diff --git a/milkymist/s6ddrphy/__init__.py b/milkymist/s6ddrphy/__init__.py
index e137b543a34ef02fc46d77a8f7bd4b73c57a66f2..02599a9dc81a219a2ec039213bd5e49189522a5f 100644 (file)
--- a/milkymist/s6ddrphy/__init__.py
+++ b/milkymist/s6ddrphy/__init__.py
@@ -101,13 +101,13 @@ class S6DDRPHY(Module):
                sd_sdram_half += [
                        pads.a.eq(r_dfi[phase_sel].address),
                        pads.ba.eq(r_dfi[phase_sel].bank),
-                       pads.cs_n.eq(r_dfi[phase_sel].cs_n),
                        pads.cke.eq(r_dfi[phase_sel].cke),
                        pads.ras_n.eq(r_dfi[phase_sel].ras_n),
                        pads.cas_n.eq(r_dfi[phase_sel].cas_n),
                        pads.we_n.eq(r_dfi[phase_sel].we_n)
                ]
-
+               if hasattr(pads, "cs_n"):
+                       sd_sdram_half += pads.cs_n.eq(r_dfi[phase_sel].cs_n)
 
                # 
                # Bitslip
@@ -181,12 +181,21 @@ class S6DDRPHY(Module):
                        )
 
                        # DQS tristate buffer
-                       self.specials += Instance("OBUFT",
-                               Instance.Input("I", dqs_o[i]),
-                               Instance.Input("T", dqs_t[i]),
-
-                               Instance.Output("O", pads.dqs[i])
-                       )
+                       if hasattr(pads, "dqs_n"):
+                               self.specials += Instance("OBUFTDS",
+                                       Instance.Input("I", dqs_o[i]),
+                                       Instance.Input("T", dqs_t[i]),
+
+                                       Instance.Output("O", pads.dqs[i]),
+                                       Instance.Output("OB", pads.dqs_n[i]),
+                               )
+                       else:
+                               self.specials += Instance("OBUFT",
+                                       Instance.Input("I", dqs_o[i]),
+                                       Instance.Input("T", dqs_t[i]),
+
+                                       Instance.Output("O", pads.dqs[i])
+                               )
 
                sd_sdram_half += postamble.eq(drive_dqs)