From ec056535dc678d9997444c08fcc8f97f1d60b5c1 Mon Sep 17 00:00:00 2001
From: Henry Cook <henry@sifive.com>
Date: Wed, 11 Oct 2017 12:44:23 -0700
Subject: [PATCH] tilelink: add DeadlockDevice

---
 src/main/scala/devices/tilelink/Error.scala | 34 ++++++++++++++++-----
 1 file changed, 26 insertions(+), 8 deletions(-)

diff --git a/src/main/scala/devices/tilelink/Error.scala b/src/main/scala/devices/tilelink/Error.scala
index cdbb95e0..3c9131bc 100644
--- a/src/main/scala/devices/tilelink/Error.scala
+++ b/src/main/scala/devices/tilelink/Error.scala
@@ -13,17 +13,13 @@ import scala.math.min
 case class ErrorParams(address: Seq[AddressSet], maxTransfer: Int = 4096)
 case object ErrorParams extends Field[ErrorParams]
 
-/** Adds a /dev/null slave that generates TL error response messages */
-class TLError(params: ErrorParams, beatBytes: Int = 4)(implicit p: Parameters) extends LazyModule
-{
-  val address = params.address
-
-  val device = new SimpleDevice("error-device", Seq("sifive,error0"))
-
+abstract class DevNullDevice(params: ErrorParams, beatBytes: Int = 4)
+                            (device: SimpleDevice)
+                            (implicit p: Parameters) extends LazyModule {
   val xfer = TransferSizes(1, params.maxTransfer)
   val node = TLManagerNode(Seq(TLManagerPortParameters(
     Seq(TLManagerParameters(
-      address            = address,
+      address            = params.address,
       resources          = device.reg("mem"),
       regionType         = RegionType.UNCACHED,
       supportsAcquireT   = xfer,
@@ -38,7 +34,12 @@ class TLError(params: ErrorParams, beatBytes: Int = 4)(implicit p: Parameters) e
     beatBytes  = beatBytes,
     endSinkId  = 1, // can receive GrantAck
     minLatency = 1))) // no bypass needed for this device
+}
 
+/** Adds a /dev/null slave that generates TL error response messages */
+class TLError(params: ErrorParams, beatBytes: Int = 4)(implicit p: Parameters)
+    extends DevNullDevice(params, beatBytes)(new SimpleDevice("error-device", Seq("sifive,error0")))
+{
   lazy val module = new LazyModuleImp(this) {
     import TLMessages._
     import TLPermissions._
@@ -88,6 +89,23 @@ class TLError(params: ErrorParams, beatBytes: Int = 4)(implicit p: Parameters) e
   }
 }
 
+/** Adds a /dev/null slave that does not raise ready for any incoming traffic.
+  * !!! WARNING: This device WILL cause your bus to deadlock for as long as you
+  *              continue to send traffic to it !!!
+  */
+class DeadlockDevice(params: ErrorParams, beatBytes: Int = 4)(implicit p: Parameters)
+    extends DevNullDevice(params, beatBytes)(new SimpleDevice("deadlock-device", Seq("sifive,deadlock0")))
+{
+  lazy val module = new LazyModuleImp(this) {
+    val (in, _) = node.in(0)
+    in.a.ready := Bool(false)
+    in.b.valid := Bool(false)
+    in.c.ready := Bool(false)
+    in.d.valid := Bool(false)
+    in.e.ready := Bool(false)
+  }
+}
+
 trait HasSystemErrorSlave extends HasSystemBus {
   private val params = p(ErrorParams)
   val error = LazyModule(new TLError(params, sbus.beatBytes))