Support externally-driven separate JTAG reset pin

ucb-bar · Aug 4, 2024 · 62aa793 · 62aa793
1 parent 30bbaf8
commit 62aa793
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Showing 4 changed files with 17 additions and 11 deletions.
diff --git a/fpga/src/main/scala/arty/HarnessBinders.scala b/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")
 

diff --git a/generators/chipyard/src/main/scala/example/FlatChipTop.scala b/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

diff --git a/generators/chipyard/src/main/scala/harness/HarnessBinders.scala b/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)
   }
 })
 

diff --git a/generators/chipyard/src/main/scala/iobinders/IOBinders.scala 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