[Voyageurs] Create an abstraction for managing TRBs.

sys/voyageurs/xhci/trb_ring.h

@@ -0,0 +1,26 @@
+#pragma once
+
+#include <glacier/container/array_view.h>
+#include <mammoth/util/memory_region.h>
+
+#include "xhci/xhci.h"
+
+class TrbRing {
+ public:
+  TrbRing();
+
+  uint64_t PhysicalAddress() { return phys_address_; }
+
+ protected:
+  uint64_t phys_address_;
+  mmth::OwnedMemoryRegion page_;
+  glcr::ArrayView<XhciTrb> trb_list_;
+};
+
+class TrbRingWriter : public TrbRing {
+ public:
+  void EnqueueTrb(const XhciTrb& trb);
+
+ private:
+  uint64_t enqueue_ptr_ = 0;
+};