rocket: allow scratchpad address to be configurable (#570)

src/main/scala/coreplex/Configs.scala

@@ -35,9 +35,17 @@ class BaseCoreplexConfig extends Config ((site, here, up) => {
 class WithNBigCores(n: Int) extends Config((site, here, up) => {
   case RocketTilesKey => {
     val big = RocketTileParams(
-      core   = RocketCoreParams(mulDiv = Some(MulDivParams(mulUnroll = 8, mulEarlyOut = true, divEarlyOut = true))),
-      dcache = Some(DCacheParams(rowBits = site(L1toL2Config).beatBytes*8, nMSHRs  = 2)),
-      icache = Some(ICacheParams(rowBits = site(L1toL2Config).beatBytes*8)))
+      core   = RocketCoreParams(mulDiv = Some(MulDivParams(
+        mulUnroll = 8,
+        mulEarlyOut = true,
+        divEarlyOut = true))),
+      dcache = Some(DCacheParams(
+        rowBits = site(L1toL2Config).beatBytes*8,
+        nMSHRs  = 2,
+        blockBytes = site(CacheBlockBytes))),
+      icache = Some(ICacheParams(
+        rowBits = site(L1toL2Config).beatBytes*8,
+        blockBytes = site(CacheBlockBytes))))
     List.fill(n)(big) ++ up(RocketTilesKey, site)
   }
 })
@@ -47,8 +55,19 @@ class WithNSmallCores(n: Int) extends Config((site, here, up) => {
     val small = RocketTileParams(
       core = RocketCoreParams(useVM = false, fpu = None),
       btb = None,
-      dcache = Some(DCacheParams(rowBits = site(L1toL2Config).beatBytes*8, nSets = 64, nWays = 1, nTLBEntries = 4, nMSHRs = 0)),
-      icache = Some(ICacheParams(rowBits = site(L1toL2Config).beatBytes*8, nSets = 64, nWays = 1, nTLBEntries = 4)))
+      dcache = Some(DCacheParams(
+        rowBits = site(L1toL2Config).beatBytes*8,
+        nSets = 64,
+        nWays = 1,
+        nTLBEntries = 4,
+        nMSHRs = 0,
+        blockBytes = site(CacheBlockBytes))),
+      icache = Some(ICacheParams(
+        rowBits = site(L1toL2Config).beatBytes*8,
+        nSets = 64,
+        nWays = 1,
+        nTLBEntries = 4,
+        blockBytes = site(CacheBlockBytes))))
     List.fill(n)(small) ++ up(RocketTilesKey, site)
   }
 })
@@ -89,19 +108,6 @@ class WithCacheBlockBytes(linesize: Int) extends Config((site, here, up) => {
   case CacheBlockBytes => linesize
 })
 
-/** Warning: applies only to the most recently added tile.
-  * TODO: For now, there can only be a single scratchpad in the design
-  *       because its address is hardcoded.
-  */
-class WithDataScratchpad(size: Int) extends Config((site, here, up) => {
-  case RocketTilesKey => {
-    val prev = up(RocketTilesKey, site)
-    prev.head.copy(
-      dcache = prev.head.dcache.map(_.copy(nSets = size / site(CacheBlockBytes))),
-      dataScratchpadBytes = size) +: prev.tail
-  }
-})
-
 class WithL2Cache extends Config(Parameters.empty) // TODO: re-add L2
 class WithL2Capacity(size_kb: Int) extends Config(Parameters.empty) // TODO: re-add L2
 class WithNL2Ways(n: Int) extends Config(Parameters.empty) // TODO: re-add L2

src/main/scala/rocket/DCache.scala

@@ -116,7 +116,6 @@ class DCacheModule(outer: DCache) extends HellaCacheModule(outer) {
   val s1_victim_way = Wire(init = replacer.way)
   val (s1_hit_way, s1_hit_state, s1_victim_meta) =
     if (usingDataScratchpad) {
-      require(nWays == 1)
       metaWriteArb.io.out.ready := true
       metaReadArb.io.out.ready := !metaWriteArb.io.out.valid
       val inScratchpad = outer.scratch().map(_.contains(s1_paddr)).getOrElse(Bool(false))

src/main/scala/rocket/HellaCache.scala

@@ -24,12 +24,22 @@ case class DCacheParams(
     nMSHRs: Int = 1,
     nSDQ: Int = 17,
     nRPQ: Int = 16,
-    nMMIOs: Int = 1) extends L1CacheParams {
+    nMMIOs: Int = 1,
+    blockBytes: Int = 64,
+    scratch: Option[BigInt] = None) extends L1CacheParams {
+
+  def dataScratchpadBytes: Int = scratch.map(_ => nSets*blockBytes).getOrElse(0)
+
   def replacement = new RandomReplacement(nWays)
+
+  require((!scratch.isDefined || nWays == 1),
+    "Scratchpad only allowed in direct-mapped cache.")
+  require((!scratch.isDefined || nMSHRs == 0),
+    "Scratchpad only allowed in blocking cache.")
+  require(isPow2(nSets), s"nSets($nSets) must be pow2")
 }
 
-trait HasL1HellaCacheParameters extends HasL1CacheParameters
-    with HasCoreParameters {
+trait HasL1HellaCacheParameters extends HasL1CacheParameters with HasCoreParameters {
   val cacheParams = tileParams.dcache.get
   val cfg = cacheParams
 
@@ -50,9 +60,8 @@ trait HasL1HellaCacheParameters extends HasL1CacheParameters
   def lrscCycles = 32 // ISA requires 16-insn LRSC sequences to succeed
   def nIOMSHRs = cacheParams.nMMIOs
   def maxUncachedInFlight = cacheParams.nMMIOs
-  def dataScratchpadSize = tileParams.dataScratchpadBytes
+  def dataScratchpadSize = cacheParams.dataScratchpadBytes
 
-  require(isPow2(nSets), s"nSets($nSets) must be pow2")
   require(rowBits >= coreDataBits, s"rowBits($rowBits) < coreDataBits($coreDataBits)")
   // TODO should rowBits even be seperably specifiable?
   require(rowBits == cacheDataBits, s"rowBits($rowBits) != cacheDataBits($cacheDataBits)") 
@@ -123,9 +132,13 @@ class HellaCacheIO(implicit p: Parameters) extends CoreBundle()(p) {
 
 abstract class HellaCache(implicit p: Parameters) extends LazyModule {
   private val cfg = p(TileKey).dcache.get
-  val node = TLClientNode(TLClientParameters(
-    sourceId = IdRange(0, cfg.nMSHRs + cfg.nMMIOs),
-    supportsProbe = TransferSizes(1, p(CacheBlockBytes))))
+  val node = TLClientNode(cfg.scratch.map { _ =>
+      TLClientParameters(sourceId = IdRange(0, cfg.nMMIOs))
+    } getOrElse {
+      TLClientParameters(
+        sourceId = IdRange(0, cfg.nMSHRs+cfg.nMMIOs),
+        supportsProbe = TransferSizes(1, cfg.blockBytes))
+    })
   val module: HellaCacheModule
 }
 

src/main/scala/rocket/ICache.scala

@@ -19,7 +19,8 @@ case class ICacheParams(
     nTLBEntries: Int = 8,
     cacheIdBits: Int = 0,
     splitMetadata: Boolean = false,
-    ecc: Option[Code] = None) extends L1CacheParams {
+    ecc: Option[Code] = None,
+    blockBytes: Int = 64) extends L1CacheParams {
   def replacement = new RandomReplacement(nWays)
 }
 

src/main/scala/rocket/ScratchpadSlavePort.scala

@@ -13,12 +13,12 @@ import uncore.tilelink2._
 import uncore.util._
 import util._
 
-class ScratchpadSlavePort(sizeBytes: Int)(implicit p: Parameters) extends LazyModule
+class ScratchpadSlavePort(address: AddressSet)(implicit p: Parameters) extends LazyModule
     with HasCoreParameters {
   val device = new MemoryDevice
   val node = TLManagerNode(Seq(TLManagerPortParameters(
     Seq(TLManagerParameters(
-      address            = List(AddressSet(0x80000000L, BigInt(sizeBytes-1))),
+      address            = List(address),
       resources          = device.reg,
       regionType         = RegionType.UNCACHED,
       executable         = true,
@@ -110,9 +110,9 @@ class ScratchpadSlavePort(sizeBytes: Int)(implicit p: Parameters) extends LazyMo
 trait CanHaveScratchpad extends HasHellaCache with HasICacheFrontend {
   val module: CanHaveScratchpadModule
 
-  val sizeBytes = tileParams.dataScratchpadBytes
+  val scratch = tileParams.dcache.flatMap(d => d.scratch.map(s =>
+    LazyModule(new ScratchpadSlavePort(AddressSet(s, d.dataScratchpadBytes-1)))))
   val slaveNode = TLInputNode()
-  val scratch   = if (sizeBytes > 0) Some(LazyModule(new ScratchpadSlavePort(sizeBytes))) else None
 
   scratch foreach { lm => lm.node := TLFragmenter(p(XLen)/8, p(CacheBlockBytes))(slaveNode) }
 
@@ -123,7 +123,7 @@ trait CanHaveScratchpad extends HasHellaCache with HasICacheFrontend {
     finalNode.get.address(0)
   }
 
-  nDCachePorts += (sizeBytes > 0).toInt
+  nDCachePorts += (scratch.isDefined).toInt
 }
 
 trait CanHaveScratchpadBundle extends HasHellaCacheBundle with HasICacheFrontendBundle {

src/main/scala/rocketchip/Configs.scala

@@ -18,6 +18,7 @@ import scala.collection.mutable.{LinkedHashSet, ListBuffer}
 import scala.collection.immutable.HashMap
 import DefaultTestSuites._
 import config._
+import tile.XLen
 
 class BasePlatformConfig extends Config((site, here, up) => {
   // DTS descriptive parameters
@@ -99,10 +100,31 @@ class HeterogeneousDualCoreConfig extends Config(
   new WithNSmallCores(1) ++ new WithNBigCores(1) ++ new WithL2Cache ++ new BaseConfig)
 
 class TinyConfig extends Config(
-  new WithScratchpad ++
-  new WithRV32 ++
+  new WithNMemoryChannels(0) ++
   new WithStatelessBridge ++
-  new WithNSmallCores(1) ++ new BaseConfig)
+  new BaseConfig().alter((site, here, up) => {
+    case XLen => 32
+    case RocketTilesKey => Seq(
+      RocketTileParams(
+        core = RocketCoreParams(
+          useVM = false,
+          fpu = None,
+          mulDiv = Some(MulDivParams(mulUnroll = 8))),
+        btb = None,
+        dcache = Some(DCacheParams(
+          rowBits = site(L1toL2Config).beatBytes*8,
+          nSets = 256, // 16Kb scratchpad
+          nWays = 1,
+          nTLBEntries = 4,
+          nMSHRs = 0,
+          blockBytes = site(CacheBlockBytes),
+          scratch = Some(0x80000000L))),
+        icache = Some(ICacheParams(
+          rowBits = site(L1toL2Config).beatBytes*8,
+          nSets = 64,
+          nWays = 1,
+          nTLBEntries = 4,
+          blockBytes = site(CacheBlockBytes)))))}))
 
 /* Composable partial function Configs to set individual parameters */
 
@@ -152,6 +174,4 @@ class WithTimebase(hertz: BigInt) extends Config((site, here, up) => {
   case DTSTimebase => hertz
 })
 
-class WithScratchpad extends Config(new WithNMemoryChannels(0) ++ new WithDataScratchpad(16384))
-
 class DefaultFPGASmallConfig extends Config(new WithNSmallCores(1) ++ new DefaultFPGAConfig)

src/main/scala/tile/BaseTile.scala

@@ -18,7 +18,6 @@ trait TileParams {
   val dcache: Option[DCacheParams]
   val rocc: Seq[RoCCParams]
   val btb: Option[BTBParams]
-  val dataScratchpadBytes: Int
 }
 
 trait HasTileParameters {
@@ -31,7 +30,7 @@ trait HasTileParameters {
   val usingRoCC = !tileParams.rocc.isEmpty
   val usingBTB = tileParams.btb.isDefined && tileParams.btb.get.nEntries > 0
   val usingPTW = usingVM
-  val usingDataScratchpad = tileParams.dcache.isDefined && tileParams.dataScratchpadBytes > 0
+  val usingDataScratchpad = tileParams.dcache.flatMap(_.scratch).isDefined
 
   def dcacheArbPorts = 1 + usingVM.toInt + usingDataScratchpad.toInt + tileParams.rocc.size
 }

src/main/scala/tile/L1Cache.scala

@@ -17,13 +17,14 @@ trait L1CacheParams {
   def nTLBEntries:   Int
   def splitMetadata: Boolean
   def ecc:           Option[Code]
+  def blockBytes:    Int
 }
 
 trait HasL1CacheParameters {
   implicit val p: Parameters
   val cacheParams: L1CacheParams
 
-  def cacheBlockBytes = p(CacheBlockBytes)
+  def cacheBlockBytes = cacheParams.blockBytes
   def lgCacheBlockBytes = log2Up(cacheBlockBytes)
   def nSets = cacheParams.nSets
   def blockOffBits = lgCacheBlockBytes