add (non-working) blocking data cache
This commit is contained in:
Andrew Waterman
285
rocket/src/main/scala/dcache.scala
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285
rocket/src/main/scala/dcache.scala
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@@ -0,0 +1,285 @@
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// See LICENSE for license details.
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package rocket
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import Chisel._
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import uncore._
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import junctions._
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import cde.{Parameters, Field}
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import Util._
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class DCacheDataReq(implicit p: Parameters) extends L1HellaCacheBundle()(p) {
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val addr = Bits(width = untagBits)
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val write = Bool()
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val wdata = Bits(width = rowBits)
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val wmask = Bits(width = rowBytes)
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val way_en = Bits(width = nWays)
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}
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class DCacheDataArray(implicit p: Parameters) extends L1HellaCacheModule()(p) {
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val io = new Bundle {
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val req = Valid(new DCacheDataReq).flip
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val resp = Vec(nWays, Bits(OUTPUT, rowBits))
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}
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val addr = io.req.bits.addr >> rowOffBits
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for (w <- 0 until nWays) {
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val array = SeqMem(nSets*refillCycles, Vec(rowBytes, Bits(width=8)))
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val valid = io.req.valid && io.req.bits.way_en(w)
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when (valid && io.req.bits.write) {
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val data = Vec.tabulate(rowBytes)(i => io.req.bits.wdata(8*(i+1)-1, 8*i))
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array.write(addr, data, io.req.bits.wmask.toBools)
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}
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io.resp(w) := array.read(addr, valid && !io.req.bits.write).toBits
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}
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}
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class DCache(implicit p: Parameters) extends L1HellaCacheModule()(p) {
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val io = new Bundle {
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val cpu = (new HellaCacheIO).flip
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val ptw = new TLBPTWIO()
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val mem = new ClientTileLinkIO
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}
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val fq = Module(new FinishQueue(1))
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require(nWays == 1) // TODO associativity
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require(rowBits == encRowBits) // no ECC
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require(refillCyclesPerBeat == 1)
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require(rowBits >= coreDataBits)
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// tags
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val replacer = p(Replacer)()
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def onReset = L1Metadata(UInt(0), ClientMetadata.onReset)
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val meta = Module(new MetadataArray(onReset _))
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val metaReadArb = Module(new Arbiter(new MetaReadReq, 2))
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val metaWriteArb = Module(new Arbiter(new L1MetaWriteReq, 3))
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meta.io.read <> metaReadArb.io.out
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meta.io.write <> metaWriteArb.io.out
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// data
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val data = Module(new DCacheDataArray)
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val dataArb = Module(new Arbiter(new DCacheDataReq, 4))
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data.io.req <> dataArb.io.out
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dataArb.io.out.ready := true
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val s1_valid = Reg(next=io.cpu.req.fire(), init=Bool(false))
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val s1_probe = Reg(next=io.mem.probe.fire(), init=Bool(false))
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val probe_bits = RegEnable(io.mem.probe.bits, io.mem.probe.fire())
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val s1_nack = Wire(init=Bool(false))
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val s1_valid_masked = s1_valid && !io.cpu.s1_kill
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val s1_valid_not_nacked = s1_valid_masked && !s1_nack
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val s1_req = RegEnable(io.cpu.req.bits, io.cpu.req.valid)
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val s1_read = isRead(s1_req.cmd)
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val s1_write = isWrite(s1_req.cmd)
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val s_ready :: s_grant_wait :: s_voluntary_writeback :: s_probe_rep_dirty :: s_probe_rep_clean :: s_probe_rep_miss :: s_voluntary_write_meta :: s_probe_write_meta :: Nil = Enum(UInt(), 8)
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val grant_wait = Reg(init=Bool(false))
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val release_state = Reg(init=s_ready)
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val pstore_valid = Reg(init=Bool(false))
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val inWriteback = release_state === s_voluntary_writeback || release_state === s_probe_rep_dirty
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io.cpu.req.ready := (release_state === s_ready) && !grant_wait && !s1_nack
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// hit initiation path
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dataArb.io.in(3).valid := io.cpu.req.valid && isRead(io.cpu.req.bits.cmd)
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dataArb.io.in(3).bits.write := false
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dataArb.io.in(3).bits.addr := io.cpu.req.bits.addr
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dataArb.io.in(3).bits.way_en := ~UInt(0, nWays)
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when (!dataArb.io.in(3).ready && isRead(io.cpu.req.bits.cmd)) { io.cpu.req.ready := false }
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metaReadArb.io.in(1).valid := io.cpu.req.valid
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metaReadArb.io.in(1).bits.idx := io.cpu.req.bits.addr(idxMSB, idxLSB)
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metaReadArb.io.in(1).bits.way_en := ~UInt(0, nWays)
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when (!metaReadArb.io.in(1).ready) { io.cpu.req.ready := false }
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// address translation
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val tlb = Module(new TLB)
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io.ptw <> tlb.io.ptw
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tlb.io.req.valid := s1_valid_masked
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tlb.io.req.bits.passthrough := s1_req.phys
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tlb.io.req.bits.asid := 0
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tlb.io.req.bits.vpn := s1_req.addr(vaddrBits-1, pgIdxBits)
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tlb.io.req.bits.instruction := false
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tlb.io.req.bits.store := s1_write
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when (!tlb.io.req.ready && !io.cpu.req.bits.phys) { io.cpu.req.ready := false }
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when (!tlb.io.req.ready && tlb.io.req.valid) { s1_nack := true }
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val s1_paddr = Cat(tlb.io.resp.ppn, s1_req.addr(pgIdxBits-1,0))
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val s1_tag = Mux(s1_probe || inWriteback, probe_bits.addr_block >> idxBits, s1_paddr(paddrBits-1, untagBits))
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val s1_hit_way = meta.io.resp.map(r => r.coh.isValid() && r.tag === s1_tag)
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val s1_hit_state = Mux1H(s1_hit_way, meta.io.resp.map(_.coh))
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val s1_data = Mux1H(s1_hit_way, data.io.resp) // retime into s2 if critical
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val s2_valid = Reg(next=s1_valid_masked, init=Bool(false))
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val s2_probe = Reg(next=s1_probe, init=Bool(false))
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val releaseInFlight = s1_probe || s2_probe || release_state =/= s_ready
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val s2_valid_masked = s2_valid && Reg(next = !s1_nack)
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val s2_req = Reg(io.cpu.req.bits)
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when (s1_valid_not_nacked) {
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s2_req := s1_req
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s2_req.addr := s1_paddr
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}
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val s2_data = RegEnable(s1_data, s1_valid || inWriteback)
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val s2_hit_way = RegEnable(Cat(s1_hit_way.reverse), s1_valid_not_nacked || s1_probe)
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val s2_hit_state = RegEnable(s1_hit_state, s1_valid_not_nacked || s1_probe)
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val s2_hit = s2_hit_state.isHit(s2_req.cmd)
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val s2_hit_dirty = s2_hit && s2_hit_state.requiresVoluntaryWriteback()
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val s2_valid_hit = s2_valid_masked && s2_hit
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val s2_valid_miss = s2_valid_masked && !s2_hit && !pstore_valid
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val s2_repl = RegEnable(meta.io.resp(replacer.way), s1_valid_not_nacked)
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val s2_repl_dirty = s2_repl.coh.requiresVoluntaryWriteback()
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io.cpu.s2_nack := s2_valid && !s2_valid_hit
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when (io.cpu.s2_nack) { s1_nack := true }
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// exceptions
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val misaligned = new StoreGen(s1_req.typ, s1_req.addr, UInt(0), wordBytes).misaligned
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io.cpu.xcpt.ma.ld := s1_read && misaligned
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io.cpu.xcpt.ma.st := s1_write && misaligned
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io.cpu.xcpt.pf.ld := s1_read && tlb.io.resp.xcpt_ld
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io.cpu.xcpt.pf.st := s1_write && tlb.io.resp.xcpt_st
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assert(!(Reg(next=
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(io.cpu.xcpt.ma.ld || io.cpu.xcpt.ma.st || io.cpu.xcpt.pf.ld || io.cpu.xcpt.pf.st)) &&
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io.cpu.resp.valid),
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"DCache exception occurred - cache response not killed.")
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// committed stores
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val s2_store_valid = s2_valid_hit && isWrite(s2_req.cmd)
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val s2_cpu_data = RegEnable(io.cpu.s1_data, s1_valid && s1_write)
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val s2_storegen = new StoreGen(s2_req.typ, s2_req.addr, s2_cpu_data, wordBytes)
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val pstore_drain = s2_store_valid || releaseInFlight || io.cpu.s2_nack || !(io.cpu.req.valid && isRead(io.cpu.req.bits.cmd))
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pstore_valid := s2_store_valid || (pstore_valid && !pstore_drain)
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val pstore_addr = RegEnable(s2_req.addr, s2_store_valid)
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val pstore_way = RegEnable(s2_hit_way, s2_store_valid)
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val pstore_data = RegEnable(s2_storegen.data, s2_store_valid)
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val pstore_mask = RegEnable(s2_storegen.mask, s2_store_valid)
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dataArb.io.in(0).valid := pstore_valid && pstore_drain
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dataArb.io.in(0).bits.write := true
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dataArb.io.in(0).bits.addr := pstore_addr
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dataArb.io.in(0).bits.way_en := pstore_way
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dataArb.io.in(0).bits.wdata := Fill(rowWords, pstore_data)
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dataArb.io.in(0).bits.wmask := pstore_mask << (if (rowOffBits > offsetlsb) (pstore_addr(rowOffBits-1,offsetlsb) << wordOffBits) else UInt(0))
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// store->load RAW hazard detection
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val s1_idx = s1_req.addr(idxMSB, wordOffBits)
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val s1_raw_hazard = s1_read &&
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((s2_store_valid && s2_req.addr(idxMSB, wordOffBits) === s1_idx) ||
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(pstore_valid && pstore_addr(idxMSB, wordOffBits) === s1_idx))
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when (s1_raw_hazard) { s1_nack := true }
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val s2_new_hit_state = s2_hit_state.onHit(s2_req.cmd)
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metaWriteArb.io.in(0).valid := s2_valid_hit && s2_hit_state =/= s2_new_hit_state
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metaWriteArb.io.in(0).bits.way_en := s2_hit_way
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metaWriteArb.io.in(0).bits.idx := s2_req.addr(idxMSB, idxLSB)
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metaWriteArb.io.in(0).bits.data.coh := s2_new_hit_state
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metaWriteArb.io.in(0).bits.data.tag := s2_req.addr(paddrBits-1, untagBits)
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// acquire
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io.mem.acquire.valid := s2_valid_miss && !s2_repl_dirty && fq.io.enq.ready
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io.mem.acquire.bits := s2_hit_state.makeAcquire(addr_block = s2_req.addr(paddrBits-1, blockOffBits), client_xact_id = UInt(0), op_code = s2_req.cmd)
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when (io.mem.acquire.fire()) { grant_wait := true }
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// grant
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val grantIsRefill = io.mem.grant.bits.hasMultibeatData()
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assert(!io.mem.grant.valid || grantIsRefill, "TODO uncached")
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val (refillCount, refillDone) = Counter(io.mem.grant.fire() && grantIsRefill, refillCycles)
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val grantDone = !grantIsRefill || refillDone
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when (io.mem.grant.fire() && grantDone) { grant_wait := false }
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// data refill
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dataArb.io.in(1).valid := grantIsRefill && io.mem.grant.valid
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io.mem.grant.ready := true
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assert(io.mem.grant.ready || !io.mem.grant.valid, "")
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dataArb.io.in(1).bits.write := true
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dataArb.io.in(1).bits.addr := Cat(s2_req.addr(paddrBits-1, blockOffBits), io.mem.grant.bits.addr_beat) << beatOffBits
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dataArb.io.in(1).bits.way_en := UIntToOH(replacer.way)
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dataArb.io.in(1).bits.wdata := io.mem.grant.bits.data
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dataArb.io.in(1).bits.wmask := ~UInt(0, rowBytes)
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// tag updates on refill
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metaWriteArb.io.in(1).valid := refillDone
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assert(!metaWriteArb.io.in(1).valid || metaWriteArb.io.in(1).ready, "")
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metaWriteArb.io.in(1).bits.way_en := UIntToOH(replacer.way)
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metaWriteArb.io.in(1).bits.idx := s2_req.addr(idxMSB, idxLSB)
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metaWriteArb.io.in(1).bits.data.coh := s2_hit_state.onGrant(io.mem.grant.bits, s2_req.cmd)
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metaWriteArb.io.in(1).bits.data.tag := s2_req.addr(paddrBits-1, untagBits)
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// probe
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metaReadArb.io.in(0).valid := io.mem.probe.valid
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io.mem.probe.ready := metaReadArb.io.in(0).ready && !releaseInFlight && !s1_valid && (!s2_valid || s2_valid_hit)
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metaReadArb.io.in(0).bits.idx := io.mem.probe.bits.addr_block
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metaReadArb.io.in(0).bits.way_en := ~UInt(0, nWays)
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// finish
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fq.io.enq.valid := refillDone
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fq.io.enq.bits := io.mem.grant.bits.makeFinish()
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io.mem.finish <> fq.io.deq
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when (fq.io.enq.valid) {
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assert(fq.io.enq.ready, "")
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replacer.miss
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}
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// release
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val (writebackCount, writebackDone) = Counter(io.mem.release.fire() && inWriteback, refillCycles)
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val releaseDone = writebackDone || (io.mem.release.fire() && !inWriteback)
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val new_coh = Wire(init = s2_hit_state.onProbe(probe_bits))
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val releaseRejected = io.mem.release.valid && !io.mem.release.ready
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val s1_release_data_valid = Reg(next = dataArb.io.in(2).fire())
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val s2_release_data_valid = Reg(next = s1_release_data_valid && !releaseRejected)
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val releaseDataBeat = Cat(UInt(0), writebackCount) + Mux(releaseRejected, UInt(0), s1_release_data_valid + Cat(UInt(0), s2_release_data_valid))
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io.mem.release.valid := s2_release_data_valid
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io.mem.release.bits := ClientMetadata.onReset.makeRelease(probe_bits)
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when (s2_valid_miss && s2_repl_dirty) {
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release_state := s_voluntary_writeback
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probe_bits.addr_block := Cat(s2_repl.tag, s2_req.addr(idxMSB, idxLSB))
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}
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when (s2_probe) {
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when (s2_hit_dirty) { release_state := s_probe_rep_dirty }
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.elsewhen (s2_hit) { release_state := s_probe_rep_clean }
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.otherwise {
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io.mem.release.valid := true
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release_state := s_probe_rep_miss
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}
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}
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when (releaseDone) { release_state := s_ready }
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when (release_state === s_probe_rep_miss || release_state === s_probe_rep_clean) {
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io.mem.release.valid := true
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}
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when (release_state === s_probe_rep_clean || release_state === s_probe_rep_dirty) {
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io.mem.release.bits := s2_hit_state.makeRelease(probe_bits)
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when (releaseDone) { release_state := s_probe_write_meta }
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}
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when (release_state === s_voluntary_writeback || release_state === s_voluntary_write_meta) {
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io.mem.release.bits := s2_hit_state.makeVoluntaryWriteback(UInt(0), UInt(0))
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new_coh := s2_hit_state.onCacheControl(M_FLUSH)
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when (releaseDone) { release_state := s_voluntary_write_meta }
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}
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when (s2_probe && !io.mem.release.fire()) { s1_nack := true }
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io.mem.release.bits.addr_block := probe_bits.addr_block
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io.mem.release.bits.addr_beat := writebackCount
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io.mem.release.bits.data := s2_data
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dataArb.io.in(2).valid := inWriteback && releaseDataBeat < refillCycles
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dataArb.io.in(2).bits.write := false
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dataArb.io.in(2).bits.addr := Cat(io.mem.release.bits.addr_block, releaseDataBeat(log2Up(refillCycles)-1,0)) << rowOffBits
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dataArb.io.in(2).bits.way_en := ~UInt(0, nWays)
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metaWriteArb.io.in(2).valid := (release_state === s_voluntary_write_meta || release_state === s_probe_write_meta)
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metaWriteArb.io.in(2).bits.way_en := s2_hit_way
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metaWriteArb.io.in(2).bits.idx := io.mem.release.bits.full_addr()(idxMSB, idxLSB)
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metaWriteArb.io.in(2).bits.data.coh := new_coh
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metaWriteArb.io.in(2).bits.data.tag := io.mem.release.bits.full_addr()(paddrBits-1, untagBits)
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when (metaWriteArb.io.in(2).fire()) { release_state := s_ready }
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// response
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io.cpu.replay_next := io.mem.grant.valid && !grantIsRefill
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io.cpu.resp.valid := s2_valid_hit || io.cpu.resp.bits.replay
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io.cpu.resp.bits := s2_req
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io.cpu.resp.bits.replay := Reg(next = io.cpu.replay_next)
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io.cpu.ordered := !(s1_valid || s2_valid || grant_wait)
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// load data subword mux/sign extension
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val s2_sc = Bool(false)
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val s2_word_idx = s2_req.addr(log2Up(rowWords*coreDataBytes)-1, log2Up(wordBytes))
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val s2_data_word = s2_data >> Cat(s2_word_idx, UInt(0, log2Up(coreDataBits)))
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val loadgen = new LoadGen(s2_req.typ, s2_req.addr, s2_data_word, s2_sc, wordBytes)
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io.cpu.resp.bits.data := loadgen.data
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io.cpu.resp.bits.data_word_bypass := loadgen.wordData
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}
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