rtio/phy: add wishbone adapter

artiq/gateware/rtio/phy/wishbone.py

@@ -0,0 +1,42 @@
+from migen.fhdl.std import *
+
+from artiq.gateware.rtio import rtlink
+
+
+class RT2WB(Module):
+    def __init__(self, wb, address_width, o_latency=0, i_latency=0):
+        self.rtlink = rtlink.Interface(
+            rtlink.OInterface(
+                flen(wb.dat_w),
+                address_width + 1,
+                latency=o_latency,
+                suppress_nop=False),
+            rtlink.IInterface(
+                flen(wb.dat_r),
+                timestamped=False,
+                latency=i_latency)
+            )
+
+        # # #
+
+        active = Signal()
+        self.sync.rio += [
+            If(self.rtlink.o.stb,
+                active.eq(1),
+                wb.adr.eq(self.rtlink.o.address[:address_width]),
+                wb.we.eq(~self.rtlink.o.address[address_width]),
+                wb.dat_w.eq(self.rtlink.o.data),
+                wb.sel.eq(2**flen(wb.sel) - 1)
+            ),
+            If(wb.ack,
+                active.eq(0)
+            )
+        ]
+        self.comb += [
+            self.rtlink.o.busy.eq(active),
+            wb.cyc.eq(active),
+            wb.stb.eq(active),
+
+            self.i.stb.eq(wb.ack & ~wb.we),
+            self.i.data.eq(wb.dat_r)
+        ]