Enabling disable all the PLLSelectorDivider features for Verilator CI

This is to work-around Verilator's modeling of reset, which does not
model a posedge reset as t=0

generators/chipyard/src/main/scala/clocking/ClockBinders.scala

@@ -14,7 +14,10 @@ import barstools.iocell.chisel._
 // blocks, which allow memory-mapped control of clock division, and clock muxing
 // between the FakePLL and the slow off-chip clock
 // Note: This will not simulate properly with firesim
-class WithPLLSelectorDividerClockGenerator extends OverrideLazyIOBinder({
+// Unsetting enable will prevent the divider/selector from actually modifying the clock,
+// while preserving the address map. Unsetting enable should only be done for RTL
+// simulators (Verilator) which do not model reset properly
+class WithPLLSelectorDividerClockGenerator(enable: Boolean = true) extends OverrideLazyIOBinder({
   (system: HasChipyardPRCI) => {
     // Connect the implicit clock
     implicit val p = GetSystemParameters(system)
@@ -30,8 +33,8 @@ class WithPLLSelectorDividerClockGenerator extends OverrideLazyIOBinder({
     }
     val tlbus = system.asInstanceOf[BaseSubsystem].locateTLBusWrapper(system.prciParams.slaveWhere)
     val baseAddress = system.prciParams.baseAddress
-    val clockDivider  = system.prci_ctrl_domain { LazyModule(new TLClockDivider (baseAddress + 0x20000, tlbus.beatBytes)) }
-    val clockSelector = system.prci_ctrl_domain { LazyModule(new TLClockSelector(baseAddress + 0x30000, tlbus.beatBytes)) }
+    val clockDivider  = system.prci_ctrl_domain { LazyModule(new TLClockDivider (baseAddress + 0x20000, tlbus.beatBytes, enable=enable)) }
+    val clockSelector = system.prci_ctrl_domain { LazyModule(new TLClockSelector(baseAddress + 0x30000, tlbus.beatBytes, enable=enable)) }
     val pllCtrl       = system.prci_ctrl_domain { LazyModule(new FakePLLCtrl    (baseAddress + 0x40000, tlbus.beatBytes)) }
 
     clockDivider.tlNode  := system.prci_ctrl_domain { TLFragmenter(tlbus.beatBytes, tlbus.blockBytes) := system.prci_ctrl_bus.get }

generators/chipyard/src/main/scala/clocking/TLClockDivider.scala

@@ -15,11 +15,27 @@ import testchipip._
 
 // This module adds a TileLink memory-mapped clock divider to the clock graph
 // The output clock/reset pairs from this module should be synchronized later
-class TLClockDivider(address: BigInt, beatBytes: Int, divBits: Int = 8)(implicit p: Parameters) extends LazyModule {
+// If enable is unset, this will not divide the clock
+// DO NOT unset enable for VLSI, or prototyping flows. The disable feature is a work around for
+// some RTL simulators which do not simulate the reset synchronization properly
+class TLClockDivider(address: BigInt, beatBytes: Int, divBits: Int = 8, enable: Boolean = true)(implicit p: Parameters) extends LazyModule {
   val device = new SimpleDevice(s"clk-div-ctrl", Nil)
   val clockNode = ClockGroupIdentityNode()
   val tlNode = TLRegisterNode(Seq(AddressSet(address, 4096-1)), device, "reg/control", beatBytes=beatBytes)
 
+  if (!enable) println(Console.RED + s"""
+
+!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+WARNING:
+
+YOU ARE USING THE TLCLOCKDIVIDER IN
+"DISABLED" MODE. THIS SHOULD ONLY BE DONE
+FOR RTL SIMULATION
+
+!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+""" + Console.RESET)
+
   lazy val module = new LazyModuleImp(this) {
     require (clockNode.out.size == 1)
     val sources = clockNode.in.head._1.member.data.toSeq
@@ -45,13 +61,21 @@ class TLClockDivider(address: BigInt, beatBytes: Int, divBits: Int = 8)(implicit
       // by setting divisor=0. The divisor signal into the ClockDividerOrPass is synchronized internally
       divider.io.divisor := Mux(busReset.asBool, 0.U, reg.io.q)
       divider.io.resetAsync := ResetStretcher(sources(i).clock, asyncReset, 20).asAsyncReset
-      sinks(i)._2.clock := divider.io.clockOut
 
-      // Note this is not synchronized to the output clock, which takes time to appear
-      // so this is still asyncreset
-      // Stretch the reset for 40 cycles, to give enough time to reset any downstream
-      // digital logic
-      sinks(i)._2.reset := ResetStretcher(sources(i).clock, asyncReset, 40).asAsyncReset
+      if (enable) {
+        sinks(i)._2.clock := divider.io.clockOut
+
+        // Note this is not synchronized to the output clock, which takes time to appear
+        // so this is still asyncreset
+        // Stretch the reset for 40 cycles, to give enough time to reset any downstream
+        // digital logic
+        sinks(i)._2.reset := ResetStretcher(sources(i).clock, asyncReset, 40).asAsyncReset
+      } else {
+        // WARNING: THIS IS FOR RTL SIMULATION ONLY
+        sinks(i)._2.clock := sources(i).clock
+        sinks(i)._2.reset := sources(i).reset
+      }
+
       reg
     }
 

generators/chipyard/src/main/scala/clocking/TLClockSelector.scala

@@ -21,12 +21,30 @@ case class ClockSelNode()(implicit valName: ValName)
 
 // This module adds a TileLink memory-mapped clock mux for each downstream clock domain
 // in the clock graph. The output clock/reset should be synchronized downstream
-class TLClockSelector(address: BigInt, beatBytes: Int)(implicit p: Parameters) extends LazyModule {
+// If enable is unset, this will always pass through the 0'th clock
+// DO NOT unset enable for VLSI, or prototyping flows. The disable feature is a work around for
+// some RTL simulators which do not simulate the reset synchronization properly
+class TLClockSelector(address: BigInt, beatBytes: Int, enable: Boolean = true)(implicit p: Parameters) extends LazyModule {
   val device = new SimpleDevice("clk-sel-ctrl", Nil)
   val tlNode = TLRegisterNode(Seq(AddressSet(address, 4096-1)), device, "reg/control", beatBytes=beatBytes)
 
   val clockNode = ClockSelNode()
 
+  if (!enable) println(Console.RED + s"""
+
+!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+WARNING:
+
+YOU ARE USING THE TLCLOCKSELECTOR IN
+"DISABLED" MODE. THIS SHOULD ONLY BE DONE
+FOR RTL SIMULATION
+
+!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+""" + Console.RESET)
+
+
+
   lazy val module = new LazyModuleImp(this) {
     val asyncReset = clockNode.in.map(_._1).map(_.reset).toSeq(0)
     val clocks = clockNode.in.map(_._1).map(_.clock)
@@ -43,10 +61,15 @@ class TLClockSelector(address: BigInt, beatBytes: Int)(implicit p: Parameters) e
       val mux = testchipip.ClockMutexMux(clocks).suggestName(s"${sinkName}_clkmux")
       mux.io.sel        := sel
       mux.io.resetAsync := asyncReset.asAsyncReset
-      sinks(i).clock := mux.io.clockOut
-      // Stretch the reset for 20 cycles, to give time to reset any downstream digital logic
-      sinks(i).reset := ResetStretcher(clocks(0), asyncReset, 20).asAsyncReset
-
+      if (enable) {
+        sinks(i).clock := mux.io.clockOut
+        // Stretch the reset for 20 cycles, to give time to reset any downstream digital logic
+        sinks(i).reset := ResetStretcher(clocks(0), asyncReset, 20).asAsyncReset
+      } else {
+        // WARNING: THIS IS FOR RTL SIMULATION ONLY
+        sinks(i).clock := clocks(0)
+        sinks(i).reset := asyncReset
+      }
       reg
     }
     tlNode.regmap((0 until sinks.size).map { i =>

generators/chipyard/src/main/scala/config/ChipConfigs.scala

@@ -110,7 +110,8 @@ class TetheredChipLikeRocketConfig extends Config(
 class VerilatorCITetheredChipLikeRocketConfig extends Config(
   new chipyard.harness.WithAbsoluteFreqHarnessClockInstantiator ++   // use absolute freqs for sims in the harness
   new chipyard.harness.WithMultiChipSerialTL(0, 1) ++                // connect the serial-tl ports of the chips together
-  new chipyard.harness.WithMultiChip(0,
+  new chipyard.harness.WithMultiChip(0,                                         // These fragments remove all troublesome
+    new chipyard.clocking.WithPLLSelectorDividerClockGenerator(enable=false) ++ // clocking features from the design
     new chipyard.iobinders.WithDebugIOCells(syncReset = false) ++
     new chipyard.config.WithNoResetSynchronizers ++
     new ChipLikeRocketConfig) ++