ArmVirtPkg/ArmVirtXen: move from VirtFdtDxe to new XenioFdtDxe driver

Now that the only functionality that remains in VirtFdtDxe is enumerating
the respective virtual I/O buses, it no longer makes sense to have a driver
that is shared between Xen domU and QEMU. So move the Xen I/O DT node
handling to a new driver, and update ArmVirtXen to switch to it.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>

ArmVirtPkg/XenioFdtDxe/XenioFdtDxe.c

@@ -0,0 +1,68 @@
+/** @file
+*  Xenio FDT client protocol driver for xen,xen DT node
+*
+*  Copyright (c) 2016, Linaro Ltd. All rights reserved.<BR>
+*
+*  This program and the accompanying materials are
+*  licensed and made available under the terms and conditions of the BSD License
+*  which accompanies this distribution.  The full text of the license may be found at
+*  http://opensource.org/licenses/bsd-license.php
+*
+*  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+*  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+*
+**/
+
+#include <Library/BaseLib.h>
+#include <Library/DebugLib.h>
+#include <Library/UefiDriverEntryPoint.h>
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/XenIoMmioLib.h>
+
+#include <Protocol/FdtClient.h>
+
+EFI_STATUS
+EFIAPI
+InitializeXenioFdtDxe (
+  IN EFI_HANDLE           ImageHandle,
+  IN EFI_SYSTEM_TABLE     *SystemTable
+  )
+{
+  EFI_STATUS            Status;
+  FDT_CLIENT_PROTOCOL   *FdtClient;
+  CONST UINT64          *Reg;
+  UINT32                RegElemSize, RegSize;
+  EFI_HANDLE            Handle;
+  UINT64                RegBase;
+
+  Status = gBS->LocateProtocol (&gFdtClientProtocolGuid, NULL,
+                  (VOID **)&FdtClient);
+  ASSERT_EFI_ERROR (Status);
+
+  Status = FdtClient->FindCompatibleNodeReg (FdtClient, "xen,xen",
+                        (CONST VOID **)&Reg, &RegElemSize, &RegSize);
+  if (EFI_ERROR (Status)) {
+    DEBUG ((EFI_D_WARN, "%a: No 'xen,xen' compatible DT node found\n",
+      __FUNCTION__));
+    return EFI_UNSUPPORTED;
+  }
+
+  ASSERT (RegSize == 16);
+
+  //
+  // Retrieve the reg base from this node and wire it up to the
+  // MMIO flavor of the XenBus root device I/O protocol
+  //
+  RegBase = SwapBytes64 (Reg[0]);
+  Handle = NULL;
+  Status = XenIoMmioInstall (&Handle, RegBase);
+  if (EFI_ERROR (Status)) {
+    DEBUG ((EFI_D_ERROR, "%a: XenIoMmioInstall () failed on a new handle "
+      "(Status == %r)\n", __FUNCTION__, Status));
+    return Status;
+  }
+
+  DEBUG ((EFI_D_INFO, "Found Xen node with Grant table @ 0x%Lx\n", RegBase));
+
+  return EFI_SUCCESS;
+}