From 4959771c97f48f16737b1ebf31c5ad5e1ff4e99b Mon Sep 17 00:00:00 2001
From: "Wesley W. Terpstra" <wesley@sifive.com>
Date: Mon, 27 Mar 2017 15:19:16 -0700
Subject: [PATCH] Revert "For D$, use source 0 through N-1 for MMIO, not 1
 through N"

This reverts commit 0538dc77ce8c0d017d8168298c4dcb99034977b7.
---
 src/main/scala/rocket/DCache.scala     | 15 ++++++++-------
 src/main/scala/rocket/HellaCache.scala |  1 +
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/src/main/scala/rocket/DCache.scala b/src/main/scala/rocket/DCache.scala
index 5f44cb00..480aa9c4 100644
--- a/src/main/scala/rocket/DCache.scala
+++ b/src/main/scala/rocket/DCache.scala
@@ -87,8 +87,9 @@ class DCacheModule(outer: DCache) extends HellaCacheModule(outer) {
   io.cpu.req.ready := (release_state === s_ready) && !cached_grant_wait && !s1_nack
 
   // I/O MSHRs
-  val uncachedInFlight = Seq.fill(cacheParams.nMMIOs) { RegInit(Bool(false)) }
-  val uncachedReqs = Seq.fill(cacheParams.nMMIOs) { Reg(new HellaCacheReq) }
+  val mmioOffset = if (outer.scratch().isDefined) 0 else 1
+  val uncachedInFlight = Seq.fill(maxUncachedInFlight) { RegInit(Bool(false)) }
+  val uncachedReqs = Seq.fill(maxUncachedInFlight) { Reg(new HellaCacheReq) }
 
   // hit initiation path
   dataArb.io.in(3).valid := io.cpu.req.valid && isRead(io.cpu.req.bits.cmd)
@@ -251,13 +252,13 @@ class DCacheModule(outer: DCache) extends HellaCacheModule(outer) {
   metaWriteArb.io.in(0).bits.data.tag := s2_req.addr(paddrBits-1, untagBits)
 
   // Prepare a TileLink request message that initiates a transaction
-  val a_source = PriorityEncoder(~uncachedInFlight.asUInt) // skip the MSHR
+  val a_source = PriorityEncoder(~uncachedInFlight.asUInt << mmioOffset) // skip the MSHR
   val acquire_address = s2_req_block_addr
   val access_address = s2_req.addr
   val a_size = s2_req.typ(MT_SZ-2, 0)
   val a_data = Fill(beatWords, pstore1_storegen.data)
   val acquire = if (edge.manager.anySupportAcquireB) {
-    edge.Acquire(UInt(cacheParams.nMMIOs), acquire_address, lgCacheBlockBytes, s2_grow_param)._2 // Cacheability checked by tlb
+    edge.Acquire(UInt(0), acquire_address, lgCacheBlockBytes, s2_grow_param)._2 // Cacheability checked by tlb
   } else {
     Wire(new TLBundleA(edge.bundle))
   }
@@ -285,7 +286,7 @@ class DCacheModule(outer: DCache) extends HellaCacheModule(outer) {
   tl_out.a.bits := Mux(!s2_uncached, acquire, Mux(!s2_write, get, Mux(!pstore1_amo, put, atomics)))
 
   // Set pending bits for outstanding TileLink transaction
-  val a_sel = UIntToOH(a_source, cacheParams.nMMIOs)
+  val a_sel = UIntToOH(a_source, maxUncachedInFlight+mmioOffset) >> mmioOffset
   when (tl_out.a.fire()) {
     when (s2_uncached) {
       (a_sel.toBools zip (uncachedInFlight zip uncachedReqs)) foreach { case (s, (f, r)) =>
@@ -312,7 +313,7 @@ class DCacheModule(outer: DCache) extends HellaCacheModule(outer) {
       assert(cached_grant_wait, "A GrantData was unexpected by the dcache.")
       when(d_last) { cached_grant_wait := false }
     } .elsewhen (grantIsUncached) {
-      val d_sel = UIntToOH(tl_out.d.bits.source, cacheParams.nMMIOs)
+      val d_sel = UIntToOH(tl_out.d.bits.source, maxUncachedInFlight+mmioOffset) >> mmioOffset
       val req = Mux1H(d_sel, uncachedReqs)
       (d_sel.toBools zip uncachedInFlight) foreach { case (s, f) =>
         when (s && d_last) {
@@ -390,7 +391,7 @@ class DCacheModule(outer: DCache) extends HellaCacheModule(outer) {
 
   val voluntaryReleaseMessage = if (edge.manager.anySupportAcquireB) {
                                 edge.Release(
-                                  fromSource = UInt(cacheParams.nMMIOs - 1),
+                                  fromSource = UInt(maxUncachedInFlight - 1),
                                   toAddress = probe_bits.address,
                                   lgSize = lgCacheBlockBytes,
                                   shrinkPermissions = s2_shrink_param,
diff --git a/src/main/scala/rocket/HellaCache.scala b/src/main/scala/rocket/HellaCache.scala
index e9ccfd88..bafd4289 100644
--- a/src/main/scala/rocket/HellaCache.scala
+++ b/src/main/scala/rocket/HellaCache.scala
@@ -60,6 +60,7 @@ trait HasL1HellaCacheParameters extends HasL1CacheParameters with HasCoreParamet
   def encRowBits = encDataBits*rowWords
   def lrscCycles = 32 // ISA requires 16-insn LRSC sequences to succeed
   def nIOMSHRs = cacheParams.nMMIOs
+  def maxUncachedInFlight = cacheParams.nMMIOs
   def dataScratchpadSize = cacheParams.dataScratchpadBytes
 
   require(rowBits >= coreDataBits, s"rowBits($rowBits) < coreDataBits($coreDataBits)")