Support externally-driven separate JTAG reset pin

fpga/src/main/scala/arty/HarnessBinders.scala

@@ -34,6 +34,7 @@ class WithArtyJTAGHarnessBinder extends HarnessBinder({
     port.io.TCK := jtag_wire.TCK
     port.io.TMS := jtag_wire.TMS
     port.io.TDI := jtag_wire.TDI
+    port.io.reset.foreach(_ := th.referenceReset)
 
     val io_jtag = Wire(new JTAGPins(() => new BasePin(), false)).suggestName("jtag")
 

fpga/src/main/scala/arty100t/HarnessBinders.scala

@@ -126,8 +126,12 @@ class WithArty100TPMODUART extends WithArty100TUART("G2", "F3")
 class WithArty100TJTAG extends HarnessBinder({
   case (th: HasHarnessInstantiators, port: JTAGPort, chipId: Int) => {
     val ath = th.asInstanceOf[LazyRawModuleImp].wrapper.asInstanceOf[Arty100THarness]
-    val harnessIO = IO(chiselTypeOf(port.io)).suggestName("jtag")
-    harnessIO <> port.io
+    val harnessIO = IO(new JTAGChipIO(false)).suggestName("jtag")
+    harnessIO.TDO := port.io.TDO
+    port.io.TCK := harnessIO.TCK
+    port.io.TDI := harnessIO.TDI
+    port.io.TMS := harnessIO.TMS
+    port.io.reset.foreach(_ := th.referenceReset)
 
     ath.sdc.addClock("JTCK", IOPin(harnessIO.TCK), 10)
     ath.sdc.addGroup(clocks = Seq("JTCK"))
@@ -138,6 +142,7 @@ class WithArty100TJTAG extends HarnessBinder({
       ("E2", IOPin(harnessIO.TDI)),
       ("D4", IOPin(harnessIO.TDO))
     )
+
     packagePinsWithPackageIOs foreach { case (pin, io) => {
       ath.xdc.addPackagePin(io, pin)
       ath.xdc.addIOStandard(io, "LVCMOS33")

fpga/src/main/scala/vcu118/HarnessBinders.scala

@@ -43,6 +43,7 @@ class WithJTAG extends HarnessBinder({
     port.io.TCK := jtag_io.TCK
     port.io.TMS := jtag_io.TMS
     port.io.TDI := jtag_io.TDI
+    port.io.reset.foreach(_ := th.referenceReset)
     jtag_io.TDO.data := port.io.TDO
     jtag_io.TDO.driven := true.B
     // ignore srst_n

generators/chipyard/src/main/scala/example/FlatChipTop.scala

@@ -131,7 +131,7 @@ class FlatChipTop(implicit p: Parameters) extends LazyModule with HasChipyardPor
     require(!debug.clockeddmi.isDefined)
     require(!debug.apb.isDefined)
     val (jtag_pad, jtagIOCells) = debug.systemjtag.map { j =>
-      val jtag_wire = Wire(new JTAGChipIO)
+      val jtag_wire = Wire(new JTAGChipIO(false))
       j.jtag.TCK := jtag_wire.TCK
       j.jtag.TMS := jtag_wire.TMS
       j.jtag.TDI := jtag_wire.TDI

generators/chipyard/src/main/scala/harness/HarnessBinders.scala

@@ -181,6 +181,7 @@ class WithSimJTAGDebug extends HarnessBinder({
     port.io.TCK := jtag_wire.TCK
     port.io.TMS := jtag_wire.TMS
     port.io.TDI := jtag_wire.TDI
+    port.io.reset.foreach(_ := th.harnessBinderReset.asBool)
     val jtag = Module(new SimJTAG(tickDelay=3))
     jtag.connect(jtag_wire, th.harnessBinderClock, th.harnessBinderReset.asBool, ~(th.harnessBinderReset.asBool), dtm_success)
   }
@@ -199,6 +200,7 @@ class WithTiedOffJTAG extends HarnessBinder({
     port.io.TCK := true.B.asClock
     port.io.TMS := true.B
     port.io.TDI := true.B
+    port.io.reset.foreach(_ := true.B)
   }
 })
 

generators/chipyard/src/main/scala/iobinders/IOBinders.scala

@@ -288,16 +288,18 @@ class WithExtInterruptIOCells extends OverrideIOBinder({
 })
 
 // Rocketchip's JTAGIO exposes the oe signal, which doesn't go off-chip
-class JTAGChipIO extends Bundle {
+class JTAGChipIO(hasReset: Boolean) extends Bundle {
   val TCK = Input(Clock())
   val TMS = Input(Bool())
   val TDI = Input(Bool())
   val TDO = Output(Bool())
+  val reset = Option.when(hasReset)(Input(Bool()))
 }
 
 // WARNING: Don't disable syncReset unless you are trying to
 // get around bugs in RTL simulators
-class WithDebugIOCells(syncReset: Boolean = true) extends OverrideLazyIOBinder({
+// If externalReset, exposes a reset in through JTAGChipIO, which is sync'd to TCK
+class WithDebugIOCells(syncReset: Boolean = true, externalReset: Boolean = true) extends OverrideLazyIOBinder({
   (system: HasPeripheryDebug) => {
     implicit val p = GetSystemParameters(system)
     val tlbus = system.asInstanceOf[BaseSubsystem].locateTLBusWrapper(p(ExportDebug).slaveWhere)
@@ -319,13 +321,6 @@ class WithDebugIOCells(syncReset: Boolean = true) extends OverrideLazyIOBinder({
           }
           // Tie off disableDebug
           d.disableDebug.foreach { d => d := false.B }
-          // Drive JTAG on-chip IOs
-          d.systemjtag.map { j =>
-            j.reset := (if (syncReset) ResetCatchAndSync(j.jtag.TCK, clockBundle.reset.asBool) else clockBundle.reset.asBool)
-            j.mfr_id := p(JtagDTMKey).idcodeManufId.U(11.W)
-            j.part_number := p(JtagDTMKey).idcodePartNum.U(16.W)
-            j.version := p(JtagDTMKey).idcodeVersion.U(4.W)
-          }
         }
         Debug.connectDebugClockAndReset(Some(debug), clockBundle.clock)
 
@@ -336,7 +331,15 @@ class WithDebugIOCells(syncReset: Boolean = true) extends OverrideLazyIOBinder({
         }
 
         val jtagTuple = debug.systemjtag.map { j =>
-          val jtag_wire = Wire(new JTAGChipIO)
+          val jtag_wire = Wire(new JTAGChipIO(externalReset))
+
+          // Drive JTAG on-chip IOs
+          val jReset = if (externalReset) jtag_wire.reset.get else clockBundle.reset.asBool
+          j.reset := (if (syncReset) ResetCatchAndSync(j.jtag.TCK, jReset) else jReset)
+          j.mfr_id := p(JtagDTMKey).idcodeManufId.U(11.W)
+          j.part_number := p(JtagDTMKey).idcodePartNum.U(16.W)
+          j.version := p(JtagDTMKey).idcodeVersion.U(4.W)
+
           j.jtag.TCK := jtag_wire.TCK
           j.jtag.TMS := jtag_wire.TMS
           j.jtag.TDI := jtag_wire.TDI