RegFieldDesc: Add utilities for generating and describing registers at the same time.

src/main/scala/util/DescribedReg.scala

@@ -0,0 +1,40 @@
+// See LICENSE for license details.
+package freechips.rocketchip.util
+
+import Chisel._
+import chisel3.experimental._
+import chisel3.{Input, Output}
+
+import freechips.rocketchip.regmapper.{RegFieldDesc}
+
+object DescribedReg {
+  import freechips.rocketchip.regmapper.RegFieldAccessType._
+
+  def apply[T <: Data](
+    gen: => T,
+    name: String,
+    desc: String,
+    reset: Option[T],
+    access: RegFieldAccessType = RW,
+    enumerations: Map[BigInt, (String, String)] = Map()): (T, RegFieldDesc) = {
+    val rdesc = RegFieldDesc(name, desc, None, None,
+      access, reset.map{_.litValue}, enumerations)
+    val reg = reset.map{i => RegInit(i)}.getOrElse(Reg(gen))
+    reg.suggestName(name + "_reg")
+    (reg, rdesc)
+  }
+
+  def async(
+    width: Int,
+    name: String,
+    desc: String,
+    reset: Int,
+    access: RegFieldAccessType = RW,
+    enumerations: Map[BigInt, (String, String)] = Map()): (SimpleRegIO, RegFieldDesc) = {
+    val rdesc = RegFieldDesc(name, desc, None, None,
+      access, Some(reset), enumerations)
+    val reg = Module(new AsyncResetRegVec(w = width, init = reset))
+    reg.suggestName(name + "_reg")
+    (reg.io, rdesc)
+  }
+}