diff --git a/src/main/scala/tilelink/ToAXI4.scala b/src/main/scala/tilelink/ToAXI4.scala
index 3d9d4784..a4588006 100644
--- a/src/main/scala/tilelink/ToAXI4.scala
+++ b/src/main/scala/tilelink/ToAXI4.scala
@@ -48,7 +48,7 @@ case class TLToAXI4Node(beatBytes: Int, stripBits: Int = 0) extends MixedAdapter
       minLatency = p.minLatency)
   })
 
-class TLToAXI4(beatBytes: Int, combinational: Boolean = true, adapterName: Option[String] = None, stripBits: Int = 0)(implicit p: Parameters) extends LazyModule
+class TLToAXI4(val beatBytes: Int, val combinational: Boolean = true, val adapterName: Option[String] = None, val stripBits: Int = 0)(implicit p: Parameters) extends LazyModule
 {
   val node = TLToAXI4Node(beatBytes, stripBits)
 
diff --git a/src/main/scala/util/Property.scala b/src/main/scala/util/Property.scala
new file mode 100644
index 00000000..f3c81672
--- /dev/null
+++ b/src/main/scala/util/Property.scala
@@ -0,0 +1,58 @@
+// See LICENSE.SiFive for license details.
+
+package freechips.rocketchip.util.property
+
+import Chisel._
+import chisel3.internal.sourceinfo.{SourceInfo, SourceLine}
+import freechips.rocketchip.config.{Field, Parameters}
+
+case object PropertyLibrary extends Field[BasePropertyLibrary](new DefaultPropertyLibrary)
+
+
+sealed abstract class PropertyType(name: String) {
+  override def toString: String = name
+}
+
+object PropertyType {
+  object Assert extends PropertyType("Assert")
+  object Assume extends PropertyType("Assume")
+  object Cover extends PropertyType("Cover")
+}
+
+trait BasePropertyParameters { 
+  val pType: PropertyType
+  val cond: Bool
+  val label: String
+  val message: String
+}
+
+case class CoverPropertyParameters(
+    cond: Bool,
+    label: String = "",
+    message: String = "") extends BasePropertyParameters {
+  val pType = PropertyType.Cover
+}
+
+abstract class BasePropertyLibrary {
+  def generateProperty(prop_param: BasePropertyParameters)(implicit sourceInfo: SourceInfo)
+}
+
+class DefaultPropertyLibrary extends BasePropertyLibrary {
+  def generateProperty(prop_param: BasePropertyParameters)(implicit sourceInfo: SourceInfo) {
+    // default is to do nothing
+    Unit
+  }
+}
+
+object cover {
+  def apply(cond: Bool)(implicit sourceInfo: SourceInfo, p: Parameters): Unit = {
+    p(PropertyLibrary).generateProperty(CoverPropertyParameters(cond))
+  }
+  def apply(cond: Bool, label: String)(implicit sourceInfo: SourceInfo, p: Parameters): Unit = {
+    p(PropertyLibrary).generateProperty(CoverPropertyParameters(cond, label))
+  }
+  def apply(cond: Bool, label: String, message: String)(implicit sourceInfo: SourceInfo, p: Parameters): Unit = {
+    p(PropertyLibrary).generateProperty(CoverPropertyParameters(cond, label, message))
+  }
+}
+