[tilelink2] Convert TileLink2 to use IrrevocableIO. Add checks to the Monitor to enforce Irrevocable semantics on TLEdges. Update the RegisterRouterTests to pass the new Monitor assertions.

src/main/scala/uncore/tilelink2/Bundles.scala

@@ -3,6 +3,7 @@
 package uncore.tilelink2
 
 import Chisel._
+import chisel3.util.Irrevocable
 
 abstract class GenericParameterizedBundle[T <: Object](val params: T) extends Bundle
 {
@@ -100,13 +101,16 @@ object TLAtomics
   def isLogical(x: UInt) = x <= SWAP
 }
 
-sealed trait TLChannel extends TLBundleBase
+sealed trait TLChannel extends TLBundleBase {
+  val channelName: String
+}
 sealed trait TLDataChannel extends TLChannel
 sealed trait TLAddrChannel extends TLDataChannel
 
 final class TLBundleA(params: TLBundleParameters)
   extends TLBundleBase(params) with TLAddrChannel
 {
+  val channelName = "'A' channel"
   // fixed fields during multibeat:
   val opcode  = UInt(width = 3)
   val param   = UInt(width = 3) // amo_opcode || perms || hint
@@ -121,6 +125,7 @@ final class TLBundleA(params: TLBundleParameters)
 final class TLBundleB(params: TLBundleParameters)
   extends TLBundleBase(params) with TLAddrChannel
 {
+  val channelName = "'B' channel"
   // fixed fields during multibeat:
   val opcode  = UInt(width = 3)
   val param   = UInt(width = 3)
@@ -135,6 +140,7 @@ final class TLBundleB(params: TLBundleParameters)
 final class TLBundleC(params: TLBundleParameters)
   extends TLBundleBase(params) with TLAddrChannel
 {
+  val channelName = "'C' channel"
   // fixed fields during multibeat:
   val opcode  = UInt(width = 3)
   val param   = UInt(width = 3)
@@ -150,6 +156,7 @@ final class TLBundleC(params: TLBundleParameters)
 final class TLBundleD(params: TLBundleParameters)
   extends TLBundleBase(params) with TLDataChannel
 {
+  val channelName = "'D' channel"
   // fixed fields during multibeat:
   val opcode  = UInt(width = 3)
   val param   = UInt(width = 2)
@@ -165,16 +172,17 @@ final class TLBundleD(params: TLBundleParameters)
 final class TLBundleE(params: TLBundleParameters)
   extends TLBundleBase(params) with TLChannel
 {
+  val channelName = "'E' channel"
   val sink = UInt(width = params.sinkBits) // to
 }
 
 class TLBundle(params: TLBundleParameters) extends TLBundleBase(params)
 {
-  val a = Decoupled(new TLBundleA(params))
+  val a = Irrevocable(new TLBundleA(params))
-  val b = Decoupled(new TLBundleB(params)).flip
+  val b = Irrevocable(new TLBundleB(params)).flip
-  val c = Decoupled(new TLBundleC(params))
+  val c = Irrevocable(new TLBundleC(params))
-  val d = Decoupled(new TLBundleD(params)).flip
+  val d = Irrevocable(new TLBundleD(params)).flip
-  val e = Decoupled(new TLBundleE(params))
+  val e = Irrevocable(new TLBundleE(params))
 }
 
 object TLBundle

src/main/scala/uncore/tilelink2/Crossing.scala

@@ -22,13 +22,13 @@ class TLAsyncCrossing(depth: Int = 8, sync: Int = 3) extends LazyModule
 
     // Transfer all TL2 bundles from/to the same domains
     ((io.in zip io.out) zip (node.edgesIn zip node.edgesOut)) foreach { case ((in, out), (edgeIn, edgeOut)) =>
-      out.a <> AsyncDecoupledCrossing(io.in_clock, io.in_reset, in.a, io.out_clock, io.out_reset, depth, sync)
+      out.a <> AsyncIrrevocableCrossing(io.in_clock, io.in_reset, in.a, io.out_clock, io.out_reset, depth, sync)
-      in.d <> AsyncDecoupledCrossing(io.out_clock, io.out_reset, out.d, io.in_clock, io.in_reset, depth, sync)
+      in.d <> AsyncIrrevocableCrossing(io.out_clock, io.out_reset, out.d, io.in_clock, io.in_reset, depth, sync)
 
       if (edgeOut.manager.anySupportAcquire && edgeOut.client.anySupportProbe) {
-        in.b <> AsyncDecoupledCrossing(io.out_clock, io.out_reset, out.b, io.in_clock, io.in_reset, depth, sync)
+        in.b <> AsyncIrrevocableCrossing(io.out_clock, io.out_reset, out.b, io.in_clock, io.in_reset, depth, sync)
-        out.c <> AsyncDecoupledCrossing(io.in_clock, io.in_reset, in.c, io.out_clock, io.out_reset, depth, sync)
+        out.c <> AsyncIrrevocableCrossing(io.in_clock, io.in_reset, in.c, io.out_clock, io.out_reset, depth, sync)
-        out.e <> AsyncDecoupledCrossing(io.in_clock, io.in_reset, in.e, io.out_clock, io.out_reset, depth, sync)
+        out.e <> AsyncIrrevocableCrossing(io.in_clock, io.in_reset, in.e, io.out_clock, io.out_reset, depth, sync)
       } else {
         in.b.valid := Bool(false)
         in.c.ready := Bool(true)

src/main/scala/uncore/tilelink2/Monitor.scala

@@ -4,6 +4,7 @@ package uncore.tilelink2
 
 import Chisel._
 import chisel3.internal.sourceinfo.{SourceInfo, SourceLine}
+import chisel3.util.{Irrevocable, IrrevocableIO}
 
 object TLMonitor
 {
@@ -14,7 +15,7 @@ object TLMonitor
     }
   }
 
-  def legalizeFormatA(bundle: TLBundleA, edge: TLEdge)(implicit sourceInfo: SourceInfo) = {
+  def legalizeFormatA(bundle: TLBundleA, edge: TLEdge)(implicit sourceInfo: SourceInfo) {
     assert (TLMessages.isA(bundle.opcode), "'A' channel has invalid opcode" + extra)
 
     // Reuse these subexpressions to save some firrtl lines
@@ -79,7 +80,7 @@ object TLMonitor
     }
   }
 
-  def legalizeFormatB(bundle: TLBundleB, edge: TLEdge)(implicit sourceInfo: SourceInfo) = {
+  def legalizeFormatB(bundle: TLBundleB, edge: TLEdge)(implicit sourceInfo: SourceInfo) {
     assert (TLMessages.isB(bundle.opcode), "'B' channel has invalid opcode" + extra)
 
     // Reuse these subexpressions to save some firrtl lines
@@ -144,7 +145,7 @@ object TLMonitor
     }
   }
 
-  def legalizeFormatC(bundle: TLBundleC, edge: TLEdge)(implicit sourceInfo: SourceInfo) = {
+  def legalizeFormatC(bundle: TLBundleC, edge: TLEdge)(implicit sourceInfo: SourceInfo) {
     assert (TLMessages.isC(bundle.opcode), "'C' channel has invalid opcode" + extra)
 
     val source_ok = edge.client.contains(bundle.source)
@@ -210,7 +211,7 @@ object TLMonitor
     }
   }
 
-  def legalizeFormatD(bundle: TLBundleD, edge: TLEdge)(implicit sourceInfo: SourceInfo) = {
+  def legalizeFormatD(bundle: TLBundleD, edge: TLEdge)(implicit sourceInfo: SourceInfo) {
     assert (TLMessages.isD(bundle.opcode), "'D' channel has invalid opcode" + extra)
 
     val source_ok = edge.client.contains(bundle.source)
@@ -268,7 +269,7 @@ object TLMonitor
     }
   }
 
-  def legalizeFormatE(bundle: TLBundleE, edge: TLEdge)(implicit sourceInfo: SourceInfo) = {
+  def legalizeFormatE(bundle: TLBundleE, edge: TLEdge)(implicit sourceInfo: SourceInfo) {
     assert (edge.manager.containsById(bundle.sink), "'E' channels carries invalid sink ID" + extra)
   }
 
@@ -280,7 +281,7 @@ object TLMonitor
     when (bundle.e.valid) { legalizeFormatE(bundle.e.bits, edge) }
   }
 
-  def legalizeMultibeatA(a: DecoupledIO[TLBundleA], edge: TLEdge)(implicit sourceInfo: SourceInfo) = {
+  def legalizeMultibeatA(a: IrrevocableIO[TLBundleA], edge: TLEdge)(implicit sourceInfo: SourceInfo) {
     val counter = RegInit(UInt(0, width = log2Up(edge.maxTransfer)))
     val opcode  = Reg(UInt())
     val param   = Reg(UInt())
@@ -307,7 +308,7 @@ object TLMonitor
     }
   }
 
-  def legalizeMultibeatB(b: DecoupledIO[TLBundleB], edge: TLEdge)(implicit sourceInfo: SourceInfo) = {
+  def legalizeMultibeatB(b: IrrevocableIO[TLBundleB], edge: TLEdge)(implicit sourceInfo: SourceInfo) {
     val counter = RegInit(UInt(0, width = log2Up(edge.maxTransfer)))
     val opcode  = Reg(UInt())
     val param   = Reg(UInt())
@@ -334,7 +335,7 @@ object TLMonitor
     }
   }
 
-  def legalizeMultibeatC(c: DecoupledIO[TLBundleC], edge: TLEdge)(implicit sourceInfo: SourceInfo) = {
+  def legalizeMultibeatC(c: IrrevocableIO[TLBundleC], edge: TLEdge)(implicit sourceInfo: SourceInfo) {
     val counter = RegInit(UInt(0, width = log2Up(edge.maxTransfer)))
     val opcode  = Reg(UInt())
     val param   = Reg(UInt())
@@ -364,7 +365,7 @@ object TLMonitor
     }
   }
 
-  def legalizeMultibeatD(d: DecoupledIO[TLBundleD], edge: TLEdge)(implicit sourceInfo: SourceInfo) = {
+  def legalizeMultibeatD(d: IrrevocableIO[TLBundleD], edge: TLEdge)(implicit sourceInfo: SourceInfo) {
     val counter = RegInit(UInt(0, width = log2Up(edge.maxTransfer)))
     val opcode  = Reg(UInt())
     val param   = Reg(UInt())
@@ -394,16 +395,37 @@ object TLMonitor
     }
   }
 
-  def legalizeMultibeat(bundle: TLBundle, edge: TLEdge)(implicit sourceInfo: SourceInfo) = {
+  def legalizeMultibeat(bundle: TLBundle, edge: TLEdge)(implicit sourceInfo: SourceInfo) {
     legalizeMultibeatA(bundle.a, edge)
     legalizeMultibeatB(bundle.b, edge)
     legalizeMultibeatC(bundle.c, edge)
     legalizeMultibeatD(bundle.d, edge)
   }
 
-  def legalize(bundle: TLBundle, edge: TLEdge)(implicit sourceInfo: SourceInfo) = {
+  def legalizeIrrevocable(irr: IrrevocableIO[TLChannel], edge: TLEdge)(implicit sourceInfo: SourceInfo) {
-    legalizeFormat   (bundle, edge)
+    val last_v = RegNext(irr.valid, Bool(false))
-    legalizeMultibeat(bundle, edge)
+    val last_r = RegNext(irr.ready, Bool(false))
+    val last_b = RegNext(irr.bits)
+    val bits_changed = irr.bits.toBits === last_b.toBits
+
+    when (last_v && !last_r) {
+      assert(irr.valid,    s"${irr.bits.channelName} had contents that were revoked by the supplier (valid lowered)" + extra)
+      assert(bits_changed, s"${irr.bits.channelName} had contents that were revoked by the supplier (contents changed)" + extra)
+    }
+  }
+
+  def legalizeIrrevocable(bundle: TLBundle, edge: TLEdge)(implicit sourceInfo: SourceInfo) {
+    legalizeIrrevocable(bundle.a, edge)
+    legalizeIrrevocable(bundle.b, edge)
+    legalizeIrrevocable(bundle.c, edge)
+    legalizeIrrevocable(bundle.d, edge)
+    legalizeIrrevocable(bundle.e, edge)
+  }
+
+  def legalize(bundle: TLBundle, edge: TLEdge)(implicit sourceInfo: SourceInfo) {
+    legalizeFormat     (bundle, edge)
+    legalizeMultibeat  (bundle, edge)
+    legalizeIrrevocable(bundle, edge)
     // !!! validate source uniqueness
   }
 }

src/main/scala/uncore/tilelink2/RegField.scala

@@ -3,7 +3,7 @@
 package uncore.tilelink2
 
 import Chisel._
-
+import chisel3.util.{Irrevocable, IrrevocableIO}
 import uncore.util.{SimpleRegIO}
 
 case class RegReadFn private(combinational: Boolean, fn: (Bool, Bool) => (Bool, Bool, UInt))
@@ -34,8 +34,8 @@ object RegReadFn
       val (ovalid, data) = x(oready)
       (Bool(true), ovalid, data)
     })
-  // read from a DecoupledIO (only safe if there is a consistent source of data)
+  // read from a IrrevocableIO (only safe if there is a consistent source of data)
-  implicit def apply(x: DecoupledIO[UInt]):RegReadFn = RegReadFn(ready => { x.ready := ready; (x.valid, x.bits) })
+  implicit def apply(x: IrrevocableIO[UInt]):RegReadFn = RegReadFn(ready => { x.ready := ready; (x.valid, x.bits) })
   // read from a register
   implicit def apply(x: UInt):RegReadFn = RegReadFn(ready => (Bool(true), x))
   // noop
@@ -69,8 +69,8 @@ object RegWriteFn
     new RegWriteFn(true, { case (_, oready, data) =>
       (Bool(true), x(oready, data))
     })
-  // write to a DecoupledIO (only safe if there is a consistent sink draining data)
+  // write to a IrrevocableIO (only safe if there is a consistent sink draining data)
-  implicit def apply(x: DecoupledIO[UInt]): RegWriteFn = RegWriteFn((valid, data) => { x.valid := valid; x.bits := data; x.ready })
+  implicit def apply(x: IrrevocableIO[UInt]): RegWriteFn = RegWriteFn((valid, data) => { x.valid := valid; x.bits := data; x.ready })
   // updates a register (or adds a mux to a wire)
   implicit def apply(x: UInt): RegWriteFn = RegWriteFn((valid, data) => { when (valid) { x := data }; Bool(true) })
   // noop

src/main/scala/uncore/tilelink2/RegMapper.scala

@@ -3,6 +3,7 @@
 package uncore.tilelink2
 
 import Chisel._
+import chisel3.util.{Irrevocable, IrrevocableIO}
 
 // A bus agnostic register interface to a register-based device
 
@@ -46,8 +47,8 @@ object RegMapper
     val endIndex = 1 << log2Ceil(regmap.map(_._1).max+1)
     val params = RegMapperParams(log2Up(endIndex), bytes, in.bits.params.extraBits)
 
-    val out = Wire(Decoupled(new RegMapperOutput(params)))
+    val out = Wire(Irrevocable(new RegMapperOutput(params)))
-    val front = Wire(Decoupled(new RegMapperInput(params)))
+    val front = Wire(Irrevocable(new RegMapperInput(params)))
     front.bits := in.bits
 
     // Must this device pipeline the control channel?

src/main/scala/uncore/tilelink2/RegisterCrossing.scala

@@ -3,6 +3,7 @@
 package uncore.tilelink2
 
 import Chisel._
+import chisel3.util.{Irrevocable, IrrevocableIO}
 import junctions._
 
 // A very simple flow control state machine, run in the specified clock domain
@@ -24,8 +25,8 @@ class BusyRegisterCrossing(clock: Clock, reset: Bool)
 
 // RegField should support connecting to one of these
 class RegisterWriteIO[T <: Data](gen: T) extends Bundle {
-  val request  = Decoupled(gen).flip()
+  val request  = Irrevocable(gen).flip()
-  val response = Decoupled(Bool()) // ignore .bits
+  val response = Irrevocable(Bool()) // ignore .bits
 }
 
 // To turn on/off a domain:
@@ -84,8 +85,8 @@ class RegisterWriteCrossing[T <: Data](gen: T, sync: Int = 3) extends Module {
 
 // RegField should support connecting to one of these
 class RegisterReadIO[T <: Data](gen: T) extends Bundle {
-  val request  = Decoupled(Bool()).flip() // ignore .bits
+  val request  = Irrevocable(Bool()).flip() // ignore .bits
-  val response = Decoupled(gen)
+  val response = Irrevocable(gen)
 }
 
 class RegisterReadCrossingIO[T <: Data](gen: T) extends Bundle {

src/main/scala/uncore/tilelink2/RegisterRouterTest.scala

@@ -33,18 +33,24 @@ class RRTestCombinational(val bits: Int, rvalid: Bool => Bool, wready: Bool => B
   io.rvalid := rvalid(rfire)
   io.wready := wready(wfire)
 
-  io.rdata := Mux(rfire, reg, UInt(0))
+  io.rdata := reg
   when (wfire) { reg := io.wdata }
 }
 
 object RRTestCombinational
 {
   private var seed = 42
+
   def always: Bool => Bool = _ => Bool(true)
-  def random: Bool => Bool = {
+
+  def random: Bool => Bool = { fire =>
     seed = seed + 1
-    _ => LFSR16Seed(seed)(0)
+    val lfsr = LFSR16Seed(seed)
+    val reg = RegInit(Bool(true))
+    reg := Mux(reg, !fire, lfsr(0) && lfsr(1))
+    reg
   }
+
   def delay(x: Int): Bool => Bool = { fire =>
     val reg = RegInit(UInt(0, width = log2Ceil(x+1)))
     val ready = reg === UInt(0)
@@ -89,7 +95,7 @@ class RRTestRequest(val bits: Int,
   val rofire = io.roready && rovalid
   val wofire = io.woready && wovalid
 
-  io.rdata := Mux(rofire, reg, UInt(0))
+  io.rdata := reg
   when (wofire) { reg := wdata }
 }
 
@@ -115,22 +121,27 @@ object RRTestRequest
     }
     (ready(0), full(x-1), data(x-1))
   }
+
   def busy: (Bool, Bool, UInt) => (Bool, Bool, UInt) = {
     seed = seed + 1
     (ivalid, oready, idata) => {
       val lfsr = LFSR16Seed(seed)
       val busy = RegInit(Bool(false))
       val data = Reg(UInt(width = idata.getWidth))
-      val progress = lfsr(0)
+      val progress = RegInit(Bool(false))
-      when (progress) {
-        busy := Mux(busy, !oready, ivalid)
-      }
       val iready = progress && !busy
       val ovalid = progress && busy
+      when (progress) {
+        busy := Mux(busy, !oready, ivalid)
+        progress := !oready
+      } .otherwise {
+        progress := lfsr(0)
+      }
       when (ivalid && iready) { data := idata }
       (iready, ovalid, data)
     }
   }
+
   def request(bits: Int,
     rflow: (Bool, Bool, UInt) => (Bool, Bool, UInt),
     wflow: (Bool, Bool, UInt) => (Bool, Bool, UInt)): RegField = {

src/main/scala/uncore/tilelink2/WidthWidget.scala

@@ -4,6 +4,7 @@ package uncore.tilelink2
 
 import Chisel._
 import chisel3.internal.sourceinfo.SourceInfo
+import chisel3.util.{Irrevocable, IrrevocableIO}
 import scala.math.{min,max}
 
 // innBeatBytes => the new client-facing bus width
@@ -19,7 +20,7 @@ class TLWidthWidget(innerBeatBytes: Int) extends LazyModule
       val out = node.bundleOut
     }
 
-    def merge[T <: TLDataChannel](edgeIn: TLEdge, in: DecoupledIO[T], edgeOut: TLEdge, out: DecoupledIO[T]) = {
+    def merge[T <: TLDataChannel](edgeIn: TLEdge, in: IrrevocableIO[T], edgeOut: TLEdge, out: IrrevocableIO[T]) = {
       val inBytes = edgeIn.manager.beatBytes
       val outBytes = edgeOut.manager.beatBytes
       val ratio = outBytes / inBytes
@@ -81,7 +82,7 @@ class TLWidthWidget(innerBeatBytes: Int) extends LazyModule
       }
     }
 
-    def split[T <: TLDataChannel](edgeIn: TLEdge, in: DecoupledIO[T], edgeOut: TLEdge, out: DecoupledIO[T]) = {
+    def split[T <: TLDataChannel](edgeIn: TLEdge, in: IrrevocableIO[T], edgeOut: TLEdge, out: IrrevocableIO[T]) = {
       val inBytes = edgeIn.manager.beatBytes
       val outBytes = edgeOut.manager.beatBytes
       val ratio = inBytes / outBytes
@@ -131,7 +132,7 @@ class TLWidthWidget(innerBeatBytes: Int) extends LazyModule
       // addr_lo gets truncated automagically
     }
     
-    def splice[T <: TLDataChannel](edgeIn: TLEdge, in: DecoupledIO[T], edgeOut: TLEdge, out: DecoupledIO[T]) = {
+    def splice[T <: TLDataChannel](edgeIn: TLEdge, in: IrrevocableIO[T], edgeOut: TLEdge, out: IrrevocableIO[T]) = {
       if (edgeIn.manager.beatBytes == edgeOut.manager.beatBytes) {
         // nothing to do; pass it through
         out <> in