Refactor package hierarchy and remove legacy bus protocol implementations (#845)

* Refactors package hierarchy.

Additionally:
  - Removes legacy ground tests and configs
  - Removes legacy bus protocol implementations
  - Removes NTiles
  - Adds devices package
  - Adds more functions to util package

src/main/scala/devices/tilelink/Error.scala

@@ -0,0 +1,57 @@
+// See LICENSE.SiFive for license details.
+
+package freechips.rocketchip.devices.tilelink
+
+import Chisel._
+import freechips.rocketchip.config.Parameters
+import freechips.rocketchip.diplomacy._
+import freechips.rocketchip.tilelink._
+import freechips.rocketchip.util._
+
+class TLError(address: Seq[AddressSet], beatBytes: Int = 4)(implicit p: Parameters) extends LazyModule
+{
+  val device = new SimpleDevice("error-device", Seq("sifive,error0"))
+
+  val node = TLManagerNode(Seq(TLManagerPortParameters(
+    Seq(TLManagerParameters(
+      address            = address,
+      resources          = device.reg("mem"),
+      supportsGet        = TransferSizes(1, beatBytes),
+      supportsPutPartial = TransferSizes(1, beatBytes),
+      supportsPutFull    = TransferSizes(1, beatBytes),
+      supportsArithmetic = TransferSizes(1, beatBytes),
+      supportsLogical    = TransferSizes(1, beatBytes),
+      supportsHint       = TransferSizes(1, beatBytes),
+      fifoId             = Some(0))), // requests are handled in order
+    beatBytes  = beatBytes,
+    minLatency = 1))) // no bypass needed for this device
+
+  lazy val module = new LazyModuleImp(this) {
+    val io = new Bundle {
+      val in = node.bundleIn
+    }
+
+    import TLMessages._
+    val opcodes = Vec(AccessAck, AccessAck, AccessAckData, AccessAckData, AccessAckData, HintAck)
+
+    val in = io.in(0)
+    val a = Queue(in.a, 1)
+    val d = in.d
+
+    a.ready := d.ready
+    d.valid := a.valid
+    d.bits.opcode  := opcodes(a.bits.opcode)
+    d.bits.param   := UInt(0)
+    d.bits.size    := a.bits.size
+    d.bits.source  := a.bits.source
+    d.bits.sink    := UInt(0)
+    d.bits.addr_lo := a.bits.address
+    d.bits.data    := UInt(0)
+    d.bits.error   := a.bits.opcode =/= Hint // Hints may not error
+
+    // Tie off unused channels
+    in.b.valid := Bool(false)
+    in.c.ready := Bool(true)
+    in.e.ready := Bool(true)
+  }
+}