Implement wire defaults for AXI4 interfaces

src/main/scala/axi/Axi4.scala

@@ -34,6 +34,12 @@ object Axi4 {
     val burst = UInt(2.W)
     val len   = UInt(8.W)
     val size  = UInt(3.W)
+
+    def defaults {
+      burst := Burst.Type.incr
+      len   := 0.U
+      size  := Burst.Size.s1
+    }
   }
 
   object Burst extends Bundle {
@@ -47,6 +53,10 @@ object Axi4 {
 
   class Lock extends Bundle {
     val lock = UInt(2.W)
+
+    def defaults {
+      lock := Lock.Access.normal
+    }
   }
 
   object Lock extends Bundle {
@@ -57,6 +67,10 @@ object Axi4 {
 
   class Cache extends Bundle {
     val cache = UInt(4.W)
+
+    def defaults {
+      cache := 0.U
+    }
   }
 
   object Cache {
@@ -103,6 +117,18 @@ object Axi4 {
     val region = if (cfg.regionWidth > 0) UInt(cfg.regionWidth) else UInt(1.W)
     val user   = if (cfg.userWidth > 0) UInt(cfg.userWidth) else UInt(1.W)
 
+    def defaults {
+      burst.defaults
+      lock.defaults
+      cache.defaults
+      prot.defaults
+      id     := 0.U
+      addr   := "hDEADBEEF".U
+      qos    := 0.U
+      region := 0.U
+      user   := 0.U
+    }
+
     override def cloneType = { new Address()(cfg).asInstanceOf[this.type] }
   }
 
@@ -161,17 +187,34 @@ object Axi4 {
       val data  = if (cfg.dataWidth > 0) UInt(cfg.dataWidth) else UInt(1.W)
       val last  = Bool()
       val user  = if (cfg.userWidth > 0) UInt(cfg.userWidth) else UInt(1.W)
+
+      def defaults {
+        id   := 0.U
+        data := "hDEADBEEF".U
+        last := true.B
+        user := 0.U
+      }
     }
 
     class Read(implicit cfg: Configuration) extends DataChannel {
       val resp  = UInt(2.W)
 
+      override def defaults {
+        super.defaults
+        resp := Response.slverr
+      }
+
       override def cloneType = { new Read()(cfg).asInstanceOf[this.type] }
     }
 
     class Write(implicit cfg: Configuration) extends DataChannel {
       val strb  = new Strobe(cfg.dataWidth)
 
+      override def defaults {
+        super.defaults
+        strb.defaults
+      }
+
       override def cloneType = { new Write()(cfg).asInstanceOf[this.type] }
     }
   }
@@ -181,6 +224,12 @@ object Axi4 {
     val buser = UInt(cfg.userWidth)
     val bresp = UInt(2.W)
 
+    def defaults {
+      bid   := 0.U
+      buser := 0.U
+      bresp := Response.slverr
+    }
+
     override def cloneType = { new WriteResponse()(cfg).asInstanceOf[this.type] }
   }
 

src/main/scala/axi/package.scala

@@ -17,6 +17,10 @@ package object axi {
 
   class Protection extends Bundle {
     val prot = UInt(3.W)
+
+    def defaults {
+      prot := Protection(Protection.Flag.NON_PRIVILEGED, Protection.Flag.NON_SECURE).U
+    }
   }
 
   object Protection {
@@ -39,6 +43,10 @@ package object axi {
   class Strobe(dataWidth: Int) extends Bundle {
     val strb = UInt((dataWidth / 8).W)
 
+    def defaults {
+      strb := Strobe(0 until dataWidth / 8 :_*)
+    }
+
     override def cloneType = { new Strobe(dataWidth).asInstanceOf[this.type] }
   }