axi4: add a RegisterRouter for generic devices

src/main/scala/uncore/axi4/RegisterRouter.scala

@@ -0,0 +1,113 @@
+// See LICENSE for license details.
+
+package uncore.axi4
+
+import Chisel._
+import diplomacy._
+import regmapper._
+import scala.math.{min,max}
+
+class AXI4RegisterNode(address: AddressSet, concurrency: Int = 0, beatBytes: Int = 4, undefZero: Boolean = true)
+  extends AXI4SlaveNode(AXI4SlavePortParameters(
+    Seq(AXI4SlaveParameters(
+      address       = Seq(address),
+      supportsWrite = TransferSizes(1, beatBytes),
+      supportsRead  = TransferSizes(1, beatBytes),
+      interleavedId = Some(0))),
+    beatBytes  = beatBytes))
+{
+  require (address.contiguous)
+
+  // Calling this method causes the matching AXI4 bundle to be
+  // configured to route all requests to the listed RegFields.
+  def regmap(mapping: RegField.Map*) = {
+    val ar = bundleIn(0).ar
+    val aw = bundleIn(0).aw
+    val w  = bundleIn(0).w
+    val r  = bundleIn(0).r
+    val b  = bundleIn(0).b
+
+    val params = RegMapperParams(log2Up((address.mask+1)/beatBytes), beatBytes, ar.bits.params.idBits)
+    val in = Wire(Decoupled(new RegMapperInput(params)))
+
+    // Prefer to execute reads first
+    in.valid := ar.valid || (aw.valid && w.valid)
+    ar.ready := in.ready
+    aw.ready := in.ready && !ar.valid && w .valid
+    w .ready := in.ready && !ar.valid && aw.valid
+
+    val addr  = Mux(ar.valid, ar.bits.addr, aw.bits.addr)
+    val in_id = Mux(ar.valid, ar.bits.id,   aw.bits.id)
+    val mask = uncore.tilelink2.maskGen(ar.bits.addr, ar.bits.size, beatBytes)
+
+    in.bits.read  := ar.valid
+    in.bits.index := addr >> log2Ceil(beatBytes)
+    in.bits.data  := w.bits.data
+    in.bits.mask  := Mux(ar.valid, mask, w.bits.strb)
+    in.bits.extra := in_id
+
+    // Invoke the register map builder and make it Irrevocable
+    val out = Queue.irrevocable(
+      RegMapper(beatBytes, concurrency, undefZero, in, mapping:_*),
+      entries = 1, pipe = true, flow = true)
+
+    // No flow control needed
+    out.ready := Mux(out.bits.read, r.ready, b.ready)
+    r.valid := out.valid &&  out.bits.read
+    b.valid := out.valid && !out.bits.read
+
+    val out_id = if (r.bits.params.idBits == 0) UInt(0) else out.bits.extra
+
+    r.bits.id   := out_id
+    r.bits.data := out.bits.data
+    r.bits.last := Bool(true)
+    r.bits.resp := AXI4Parameters.RESP_OKAY
+    b.bits.id   := out_id
+    b.bits.resp := AXI4Parameters.RESP_OKAY
+  }
+}
+
+object AXI4RegisterNode
+{
+  def apply(address: AddressSet, concurrency: Int = 0, beatBytes: Int = 4, undefZero: Boolean = true) =
+    new AXI4RegisterNode(address, concurrency, beatBytes, undefZero)
+}
+
+// These convenience methods below combine to make it possible to create a AXI4
+// register mapped device from a totally abstract register mapped device.
+
+abstract class AXI4RegisterRouterBase(address: AddressSet, interrupts: Int, concurrency: Int, beatBytes: Int, undefZero: Boolean) extends LazyModule
+{
+  val node = AXI4RegisterNode(address, concurrency, beatBytes, undefZero)
+  val intnode = uncore.tilelink2.IntSourceNode(interrupts)
+}
+
+case class AXI4RegBundleArg(interrupts: Vec[Vec[Bool]], in: Vec[AXI4Bundle])
+
+class AXI4RegBundleBase(arg: AXI4RegBundleArg) extends Bundle
+{
+  val interrupts = arg.interrupts
+  val in = arg.in
+}
+
+class AXI4RegBundle[P](val params: P, arg: AXI4RegBundleArg) extends AXI4RegBundleBase(arg)
+
+class AXI4RegModule[P, B <: AXI4RegBundleBase](val params: P, bundleBuilder: => B, router: AXI4RegisterRouterBase)
+  extends LazyModuleImp(router) with HasRegMap
+{
+  val io = bundleBuilder
+  val interrupts = if (io.interrupts.isEmpty) Vec(0, Bool()) else io.interrupts(0)
+  def regmap(mapping: RegField.Map*) = router.node.regmap(mapping:_*)
+}
+
+class AXI4RegisterRouter[B <: AXI4RegBundleBase, M <: LazyModuleImp]
+   (val base: BigInt, val interrupts: Int = 0, val size: BigInt = 4096, val concurrency: Int = 0, val beatBytes: Int = 4, undefZero: Boolean = true)
+   (bundleBuilder: AXI4RegBundleArg => B)
+   (moduleBuilder: (=> B, AXI4RegisterRouterBase) => M)
+  extends AXI4RegisterRouterBase(AddressSet(base, size-1), interrupts, concurrency, beatBytes, undefZero)
+{
+  require (isPow2(size))
+  // require (size >= 4096) ... not absolutely required, but highly recommended
+
+  lazy val module = moduleBuilder(bundleBuilder(AXI4RegBundleArg(intnode.bundleOut, node.bundleIn)), this)
+}