Start adding RoCC

rocket/src/main/scala/core.scala

@@ -10,6 +10,7 @@ class RocketIO(implicit conf: RocketConfiguration) extends Bundle
   val imem = new CPUFrontendIO()(conf.icache)
   val dmem = new HellaCacheIO()(conf.dcache)
   val ptw = new DatapathPTWIO().flip
+  val rocc = new RoCCInterface().flip
 }
 
 class Core(implicit conf: RocketConfiguration) extends Module
@@ -19,6 +20,15 @@ class Core(implicit conf: RocketConfiguration) extends Module
   val ctrl  = Module(new Control)
   val dpath = Module(new Datapath)
 
+  val fpu: FPU = if (conf.fpu) {
+    val fpu = Module(new FPU(4,6))
+    dpath.io.fpu <> fpu.io.dpath
+    ctrl.io.fpu <> fpu.io.ctrl
+    fpu.io.sfma.valid := Bool(false) // hook these up to coprocessor?
+    fpu.io.dfma.valid := Bool(false)
+    fpu
+  } else null
+
   ctrl.io.dpath <> dpath.io.ctrl
   dpath.io.host <> io.host
 
@@ -30,12 +40,6 @@ class Core(implicit conf: RocketConfiguration) extends Module
 
   dpath.io.ptw <> io.ptw
 
-  val fpu: FPU = if (conf.fpu) {
-    val fpu = Module(new FPU(4,6))
-    dpath.io.fpu <> fpu.io.dpath
-    ctrl.io.fpu <> fpu.io.ctrl
-    fpu.io.sfma.valid := Bool(false) // hook these up to coprocessor?
-    fpu.io.dfma.valid := Bool(false)
-    fpu
-  } else null
+  ctrl.io.rocc <> io.rocc
+  dpath.io.rocc <> io.rocc
 }

rocket/src/main/scala/ctrl.scala

@@ -37,7 +37,8 @@ class CtrlDpathIO extends Bundle()
   val wb_valid = Bool(OUTPUT)
   val ex_mem_type = Bits(OUTPUT, 3)
   val ex_rs2_val = Bool(OUTPUT)
-  val mem_rs2_val = Bool(OUTPUT)
+  val ex_rocc_val = Bool(OUTPUT)
+  val mem_rocc_val = Bool(OUTPUT)
   val mem_ll_bypass_rs1 = Bool(OUTPUT)
   val mem_ll_bypass_rs2 = Bool(OUTPUT)
   // exception handling
@@ -317,6 +318,7 @@ class Control(implicit conf: RocketConfiguration) extends Module
     val xcpt_dtlb_ld = Bool(INPUT)
     val xcpt_dtlb_st = Bool(INPUT)
     val fpu = new CtrlFPUIO
+    val rocc = new RoCCInterface().flip
   }
 
   var decode_table = XDecode.table
@@ -376,6 +378,7 @@ class Control(implicit conf: RocketConfiguration) extends Module
   val wb_reg_pcr             = Reg(init=PCR.N)
   val wb_reg_wen             = Reg(init=Bool(false))
   val wb_reg_fp_wen          = Reg(init=Bool(false))
+  val wb_reg_rocc_val        = Reg(init=Bool(false))
   val wb_reg_flush_inst      = Reg(init=Bool(false))
   val wb_reg_mem_val         = Reg(init=Bool(false))
   val wb_reg_eret            = Reg(init=Bool(false))
@@ -416,9 +419,11 @@ class Control(implicit conf: RocketConfiguration) extends Module
   val id_amo_aq = io.dpath.inst(16)
   val id_amo_rl = io.dpath.inst(15)
   val id_fence_next = id_fence || id_amo && id_amo_rl
-  val id_fence_ok = io.dmem.ordered && !ex_reg_mem_val
+  val id_rocc_busy = io.rocc.busy || ex_reg_rocc_val || mem_reg_rocc_val || wb_reg_rocc_val
+  val id_fence_ok = io.dmem.ordered && !ex_reg_mem_val &&
+    (Bool(conf.rocc.isEmpty) || !id_rocc_busy)
   id_reg_fence := id_fence_next || id_reg_fence && !id_fence_ok
-  val id_do_fence = id_amo && id_amo_aq || id_reg_fence && id_mem_val || id_pcr_flush
+  val id_do_fence = id_amo && id_amo_aq || id_reg_fence && (id_mem_val || id_rocc_val) || id_pcr_flush
 
   val (id_xcpt, id_cause) = checkExceptions(List(
     (id_interrupt,                            id_interrupt_cause),
@@ -549,6 +554,7 @@ class Control(implicit conf: RocketConfiguration) extends Module
     wb_reg_mem_val     := Bool(false)
     wb_reg_div_mul_val := Bool(false);
     wb_reg_fp_val      := Bool(false)
+    wb_reg_rocc_val := Bool(false)
   }
   .otherwise {
     wb_reg_valid       := mem_reg_valid
@@ -560,9 +566,11 @@ class Control(implicit conf: RocketConfiguration) extends Module
     wb_reg_mem_val     := mem_reg_mem_val
     wb_reg_div_mul_val := mem_reg_div_mul_val
     wb_reg_fp_val      := mem_reg_fp_val
+    wb_reg_rocc_val := mem_reg_rocc_val
   }
 
-  val replay_wb = io.dmem.resp.bits.nack || wb_reg_replay || io.dpath.pcr_replay
+  val replay_wb = io.dmem.resp.bits.nack || wb_reg_replay ||
+    io.dpath.pcr_replay || Bool(!conf.rocc.isEmpty) && wb_reg_rocc_val && !io.rocc.cmd.ready
 
   class Scoreboard(n: Int)
   {
@@ -708,7 +716,8 @@ class Control(implicit conf: RocketConfiguration) extends Module
   io.dpath.ex_mem_type := ex_reg_mem_type
   io.dpath.ex_br_type := ex_reg_br_type
   io.dpath.ex_rs2_val := ex_reg_mem_val && isWrite(ex_reg_mem_cmd) || ex_reg_rocc_val
-  io.dpath.mem_rs2_val := mem_reg_rocc_val
+  io.dpath.ex_rocc_val := ex_reg_rocc_val
+  io.dpath.mem_rocc_val := mem_reg_rocc_val
 
   io.fpu.valid := !ctrl_killd && id_fp_val
   io.fpu.killx := ctrl_killx
@@ -719,4 +728,6 @@ class Control(implicit conf: RocketConfiguration) extends Module
   io.dmem.req.bits.cmd  := ex_reg_mem_cmd
   io.dmem.req.bits.typ  := ex_reg_mem_type
   io.dmem.req.bits.phys := Bool(false)
+
+  io.rocc.cmd.valid := wb_reg_rocc_val
 }

rocket/src/main/scala/dpath.scala

@@ -14,6 +14,7 @@ class Datapath(implicit conf: RocketConfiguration) extends Module
     val ptw = (new DatapathPTWIO).flip
     val imem  = new CPUFrontendIO()(conf.icache)
     val fpu = new DpathFPUIO
+    val rocc = new RoCCInterface().flip
   }
 
   // execute definitions
@@ -39,8 +40,6 @@ class Datapath(implicit conf: RocketConfiguration) extends Module
   val mem_reg_wdata = Reg(Bits())
   val mem_reg_kill = Reg(Bool())
   val mem_reg_store_data = Reg(Bits())
-  val mem_reg_rs1 = Reg(Bits())
-  val mem_reg_rs2 = Reg(Bits())
   
   // writeback definitions
   val wb_reg_pc = Reg(UInt())
@@ -49,8 +48,6 @@ class Datapath(implicit conf: RocketConfiguration) extends Module
   val wb_reg_wdata = Reg(Bits())
   val wb_reg_ll_wb = Reg(init=Bool(false))
   val wb_wdata = Bits()
-  val wb_reg_store_data = Reg(Bits())
-  val wb_reg_rs1 = Reg(Bits())
   val wb_reg_rs2 = Reg(Bits())
   val wb_wen = io.ctrl.wb_wen && io.ctrl.wb_valid || wb_reg_ll_wb
 
@@ -235,8 +232,6 @@ class Datapath(implicit conf: RocketConfiguration) extends Module
     mem_reg_pc := ex_reg_pc
     mem_reg_inst := ex_reg_inst
     mem_reg_wdata := ex_wdata
-    mem_reg_rs1 := ex_rs1
-    mem_reg_rs2 := ex_rs2
     when (io.ctrl.ex_rs2_val) {
       mem_reg_store_data := StoreGen(io.ctrl.ex_mem_type, Bits(0), ex_rs2).data
     }
@@ -255,8 +250,19 @@ class Datapath(implicit conf: RocketConfiguration) extends Module
   mem_ll_wdata := div.io.resp.bits.data
   io.ctrl.mem_ll_waddr := div.io.resp.bits.tag
   io.ctrl.mem_ll_wb := div.io.resp.valid && !io.ctrl.mem_wen
+  if (!conf.rocc.isEmpty) {
+    io.rocc.resp.ready := !io.ctrl.mem_wen && !io.ctrl.mem_rocc_val
+    when (io.rocc.resp.fire()) {
+      div.io.resp.ready := Bool(false)
+      mem_ll_wdata := io.rocc.resp.bits.data
+      io.ctrl.mem_ll_waddr := io.rocc.resp.bits.rd
+      io.ctrl.mem_ll_wb := Bool(true)
+    }
+  }
   when (dmem_resp_replay) {
     div.io.resp.ready := Bool(false)
+    if (!conf.rocc.isEmpty)
+      io.rocc.resp.ready := Bool(false)
     mem_ll_wdata := io.dmem.resp.bits.data_subword
     io.ctrl.mem_ll_waddr := dmem_resp_waddr
     io.ctrl.mem_ll_wb := Bool(true)
@@ -274,11 +280,9 @@ class Datapath(implicit conf: RocketConfiguration) extends Module
     wb_reg_waddr := io.ctrl.mem_waddr
     wb_reg_inst := mem_reg_inst
     wb_reg_wdata := Mux(io.ctrl.mem_fp_val && io.ctrl.mem_wen, io.fpu.toint_data, mem_reg_wdata)
-    wb_reg_rs1 := mem_reg_rs1
-    wb_reg_rs2 := mem_reg_rs2
-    when (io.ctrl.mem_rs2_val) {
-      wb_reg_store_data := mem_reg_store_data
-    }
+  }
+  when (io.ctrl.mem_rocc_val) {
+    wb_reg_rs2 := Bits(0)//mem_reg_rs2
   }
   wb_reg_ll_wb := io.ctrl.mem_ll_wb
   when (io.ctrl.mem_ll_wb) {
@@ -301,6 +305,10 @@ class Datapath(implicit conf: RocketConfiguration) extends Module
   pcr.io.rw.cmd  := io.ctrl.pcr
   pcr.io.rw.wdata := wb_reg_wdata
 
+  io.rocc.cmd.bits.inst := new RoCCInstruction().fromBits(wb_reg_inst)
+  io.rocc.cmd.bits.rs1 := wb_reg_wdata
+  io.rocc.cmd.bits.rs2 := wb_reg_rs2
+
   // hook up I$
   io.imem.req.bits.currentpc := ex_reg_pc
   io.imem.req.bits.pc :=
@@ -311,7 +319,7 @@ class Datapath(implicit conf: RocketConfiguration) extends Module
   printf("C: %d [%d] pc=[%x] W[r%d=%x] R[r%d=%x] R[r%d=%x] inst=[%x] %s\n",
          tsc_reg(32,0), io.ctrl.wb_valid, wb_reg_pc,
          Mux(wb_wen, wb_reg_waddr, UInt(0)), wb_wdata,
-         wb_reg_inst(26,22), wb_reg_rs1,
-         wb_reg_inst(21,17), wb_reg_rs2,
+         wb_reg_inst(26,22), Reg(next=Reg(next=ex_rs1)),
+         wb_reg_inst(21,17), Reg(next=Reg(next=ex_rs2)),
          wb_reg_inst, Disassemble(wb_reg_inst))
 }

rocket/src/main/scala/rocc.scala

@@ -3,4 +3,68 @@ package rocket
 import Chisel._
 import Node._
 
-abstract class RoCC extends Module
+class RoCCInstruction extends Bundle
+{
+  val rd = Bits(width = 5)
+  val rs1 = Bits(width = 5)
+  val rs2 = Bits(width = 5)
+  val funct = Bits(width = 7)
+  val xd = Bool()
+  val xs1 = Bool()
+  val xs2 = Bool()
+  val opcode = Bits(width = 7)
+}
+
+class RoCCCommand(implicit conf: RocketConfiguration) extends Bundle
+{
+  val inst = new RoCCInstruction
+  val rs1 = Bits(width = conf.xprlen)
+  val rs2 = Bits(width = conf.xprlen)
+
+  override def clone = new RoCCCommand().asInstanceOf[this.type]
+}
+
+class RoCCResponse(implicit conf: RocketConfiguration) extends Bundle
+{
+  val rd = Bits(width = 5)
+  val data = Bits(width = conf.xprlen)
+
+  override def clone = new RoCCResponse().asInstanceOf[this.type]
+}
+
+class RoCCInterface(implicit conf: RocketConfiguration) extends Bundle
+{
+  val cmd = Decoupled(new RoCCCommand).flip
+  val resp = Decoupled(new RoCCResponse)
+  val busy = Bool(OUTPUT)
+  val interrupt = Bool(OUTPUT)
+
+  override def clone = new RoCCInterface().asInstanceOf[this.type]
+}
+
+abstract class RoCC(implicit conf: RocketConfiguration) extends Module
+{
+  val io = new RoCCInterface
+}
+
+class AccumulatorExample(implicit conf: RocketConfiguration) extends RoCC
+{
+  val regfile = Mem(UInt(width = conf.xprlen), 4)
+
+  val funct = io.cmd.bits.inst.funct
+  val addr = io.cmd.bits.inst.rs2
+  val addend = io.cmd.bits.rs1
+  val accum = regfile(addr)
+  val wdata = Mux(funct === UInt(0), addend, accum + addend)
+
+  when (io.cmd.fire() && (funct === UInt(1) || funct === UInt(3))) {
+    regfile(addr) := wdata
+  }
+
+  io.cmd.ready := io.resp.ready
+  io.resp.valid := io.cmd.valid && io.cmd.bits.inst.xd
+  io.resp.bits.rd := io.cmd.bits.inst.rd
+  io.resp.bits.data := accum
+  io.busy := Bool(false)
+  io.interrupt := Bool(false)
+}