cleanup scratchpad nodes

src/main/scala/rocket/Frontend.scala

@@ -45,21 +45,18 @@ class FrontendIO(implicit p: Parameters) extends CoreBundle()(p) {
 class Frontend(hartid: Int)(implicit p: Parameters) extends LazyModule {
   lazy val module = new FrontendModule(this)
   val icache = LazyModule(new ICache(latency = 2, hartid))
-  val node = TLOutputNode()
+  val masterNode = TLOutputNode()
-  val slaveNode = icache.slaveNode.map { n =>
+  val slaveNode = TLInputNode()
-    val res = TLInputNode()
-    n := res
-    res
-  }
 
-  node := icache.node
+  icache.slaveNode.map { _ := slaveNode }
+  masterNode := icache.masterNode
 }
 
 class FrontendBundle(outer: Frontend) extends CoreBundle()(outer.p) {
   val cpu = new FrontendIO().flip
   val ptw = new TLBPTWIO()
-  val tl_out = outer.node.bundleOut
+  val tl_out = outer.masterNode.bundleOut
-  val tl_in = outer.slaveNode.map(_.bundleIn)
+  val tl_in = outer.slaveNode.bundleIn
   val resetVector = UInt(INPUT, vaddrBitsExtended)
   val hartid = UInt(INPUT, hartIdLen)
 }
@@ -68,7 +65,7 @@ class FrontendModule(outer: Frontend) extends LazyModuleImp(outer)
     with HasCoreParameters
     with HasL1ICacheParameters {
   val io = new FrontendBundle(outer)
-  implicit val edge = outer.node.edgesOut(0)
+  implicit val edge = outer.masterNode.edgesOut.head
   val icache = outer.icache.module
 
   val tlb = Module(new TLB(log2Ceil(coreInstBytes*fetchWidth), nTLBEntries))
@@ -186,7 +183,7 @@ trait HasICacheFrontend extends CanHavePTW with HasTileLinkMasterPort {
   val module: HasICacheFrontendModule
   val frontend = LazyModule(new Frontend(hartid: Int))
   val hartid: Int
-  masterNode := frontend.node
+  masterNode := frontend.masterNode
   nPTWPorts += 1
 }
 

src/main/scala/rocket/ICache.scala

@@ -35,7 +35,7 @@ class ICacheReq(implicit p: Parameters) extends CoreBundle()(p) with HasL1ICache
 class ICache(val latency: Int, val hartid: Int)(implicit p: Parameters) extends LazyModule
     with HasRocketCoreParameters {
   lazy val module = new ICacheModule(this)
-  val node = TLClientNode(TLClientParameters(sourceId = IdRange(0,1)))
+  val masterNode = TLClientNode(TLClientParameters(sourceId = IdRange(0,1)))
 
   val icacheParams = tileParams.icache.get
   val size = icacheParams.nSets * icacheParams.nWays * icacheParams.blockBytes
@@ -64,7 +64,7 @@ class ICacheBundle(outer: ICache) extends CoreBundle()(outer.p) {
 
   val resp = Valid(UInt(width = coreInstBits * fetchWidth))
   val invalidate = Bool(INPUT)
-  val tl_out = outer.node.bundleOut
+  val tl_out = outer.masterNode.bundleOut
   val tl_in = outer.slaveNode.map(_.bundleIn)
 }
 
@@ -78,7 +78,7 @@ object GetPropertyByHartId {
 class ICacheModule(outer: ICache) extends LazyModuleImp(outer)
     with HasL1ICacheParameters {
   val io = new ICacheBundle(outer)
-  val edge_out = outer.node.edgesOut.head
+  val edge_out = outer.masterNode.edgesOut.head
   val tl_out = io.tl_out.head
   val edge_in = outer.slaveNode.map(_.edgesIn.head)
   val tl_in = io.tl_in.map(_.head)

src/main/scala/rocket/ScratchpadSlavePort.scala

@@ -108,18 +108,22 @@ class ScratchpadSlavePort(address: AddressSet)(implicit p: Parameters) extends L
 trait CanHaveScratchpad extends HasHellaCache with HasICacheFrontend with HasCoreParameters {
   val module: CanHaveScratchpadModule
 
+  val slaveNode = TLInputNode() // Up to two uses for this input node:
+
+  // 1) Frontend always exists, but may or may not have a scratchpad node
+  val fg = LazyModule(new TLFragmenter(fetchWidth*coreInstBytes, p(CacheBlockBytes), true))
+  val ww = LazyModule(new TLWidthWidget(xLen/8))
+  frontend.slaveNode :*= ww.node
+  ww.node :*= fg.node
+  fg.node :*= slaveNode
+
+  // 2) ScratchpadSlavePort always has a node, but only exists when the HellaCache has a scratchpad
   val scratch = tileParams.dcache.flatMap(d => d.scratch.map(s =>
     LazyModule(new ScratchpadSlavePort(AddressSet(s, d.dataScratchpadBytes-1)))))
-  val slaveNode = TLInputNode()
+  scratch foreach { lm => lm.node := TLFragmenter(xLen/8, p(CacheBlockBytes))(slaveNode) }
-
-  scratch foreach { lm => lm.node := TLFragmenter(p(XLen)/8, p(CacheBlockBytes))(slaveNode) }
-  frontend.slaveNode foreach { _ :=
-    TLFragmenter(fetchWidth*coreInstBytes, p(CacheBlockBytes), true)(
-      TLWidthWidget(p(XLen)/8)(slaveNode))
-  }
 
   def findScratchpadFromICache: Option[AddressSet] = scratch.map { s =>
-    val finalNode = frontend.node.edgesOut(0).manager.managers.find(_.nodePath.last == s.node)
+    val finalNode = frontend.masterNode.edgesOut.head.manager.managers.find(_.nodePath.last == s.node)
     require (finalNode.isDefined, "Could not find the scratch pad; not reachable via icache?")
     require (finalNode.get.address.size == 1, "Scratchpad address space was fragmented!")
     finalNode.get.address(0)