ICE40Platform: ubtnReset is opt-in.

README.md

@@ -10,4 +10,3 @@ its own HDL depending on how much I love Scala. :)
 * Generate PCFs on demand via board descriptions.
 * Tie this all together with SV generation — lowering options should be here,
   not in user code.
-* iCE40 UBTN reset should be opt in.

src/main/scala/ee/hrzn/chryse/platform/ice40/ICE40Platform.scala

@@ -5,7 +5,8 @@ import ee.hrzn.chryse.HasIO
 import ee.hrzn.chryse.platform.ElaboratablePlatform
 import ee.hrzn.chryse.platform.Platform
 
-case object ICE40Platform extends ElaboratablePlatform {
+case class ICE40Platform(ubtnReset: Boolean = false)
+    extends ElaboratablePlatform {
   val id      = "ice40"
   val clockHz = 12_000_000
 

src/main/scala/ee/hrzn/chryse/platform/ice40/ICE40Top.scala

@@ -1,6 +1,7 @@
 package ee.hrzn.chryse.platform.ice40
 
 import chisel3._
+import chisel3.experimental.noPrefix
 import chisel3.util._
 import ee.hrzn.chryse.HasIO
 import ee.hrzn.chryse.platform.Platform
@@ -28,10 +29,18 @@ class ICE40Top[Top <: HasIO[_ <: Data]](genTop: => Top)(implicit
     reset         := true.B
     resetTimerReg := resetTimerReg + 1.U
   }
-  private val io_ubtn = IO(Input(Bool()))
+
+  val finalReset = noPrefix {
+    if (platform.asInstanceOf[ICE40Platform].ubtnReset) {
+      val io_ubtn = IO(Input(Bool()))
+      reset | ~io_ubtn
+    } else {
+      reset
+    }
+  }
 
   private val top =
-    withClockAndReset(clk, reset | ~io_ubtn)(Module(genTop))
+    withClockAndReset(clk, finalReset)(Module(genTop))
   private val io = IO(top.createIo())
   io :<>= top.io.as[Data]
 }