Move terminal into own clock domain using AsyncQueue

src/main/scala/devices/terminal/Terminal.scala

@@ -9,6 +9,7 @@ import freechips.rocketchip.diplomacy.{LazyModule, LazyModuleImp}
 import freechips.rocketchip.regmapper._
 import freechips.rocketchip.subsystem.{BaseSubsystem}
 import freechips.rocketchip.tilelink._
+import freechips.rocketchip.util.AsyncQueue
 
 
 case class TerminalParams (
@@ -56,10 +57,22 @@ trait TerminalRegModule extends MultiIOModule with HasRegMap {
     io.port_sys <> term.io.sys
     io.port_dvi <> term.io.dvi
 
+    val crossing = Module(new AsyncQueue(UInt(8.W), depth=1, safe=false))
+
+    crossing.io.enq_clock := clock
+    crossing.io.enq_reset := Bool(false)
+    crossing.io.deq_clock := io.port_sys.clk
+    crossing.io.deq_reset := Bool(false)
+
+    // wire up dequeue to terminal io
+    term.io.write_enable := crossing.io.deq.valid
+    term.io.write_data := crossing.io.deq.bits
+    crossing.io.deq.ready := Bool(true) // terminal can read at every cycle
+
     val writer_fn = (valid: Bool, data: UInt) => {
-        term.io.write_enable := valid
-        term.io.write_data := data
-        Bool(true) // terminal can read at every cycle
+        crossing.io.enq.valid := valid
+        crossing.io.enq.bits := data
+        Bool(true) // discards values if queue is full (see NonBlockingEnqueue)
     }
 
     regmap(