OvmfPkg: Add bhyve support into AcpiTimerLib

On bhyve, the ACPI timer is located at a fixed IO address; it need
not be programmed into, nor fetched from, the PMBA -- power
management base address -- register of the PCI host bridge.

Signed-off-by: Rebecca Cran <rebecca@bsdio.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Message-Id: <20200430011212.612386-1-rebecca@bsdio.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>

OvmfPkg/Include/IndustryStandard/Bhyve.h

@@ -0,0 +1,16 @@
+/** @file
+  Various register numbers and value bits based on FreeBSD's bhyve
+  at r359530.
+  - https://svnweb.freebsd.org/base?view=revision&revision=359530
+
+  Copyright (C) 2020, Rebecca Cran <rebecca@bsdio.com>
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#ifndef __BHYVE_H__
+#define __BHYVE_H__
+
+#define BHYVE_ACPI_TIMER_IO_ADDR 0x408
+
+#endif // __BHYVE_H__

OvmfPkg/Include/OvmfPlatforms.h

@@ -14,6 +14,7 @@
 #include <IndustryStandard/Pci22.h>
 #include <IndustryStandard/Q35MchIch9.h>
 #include <IndustryStandard/I440FxPiix4.h>
+#include <IndustryStandard/Bhyve.h>
 
 //
 // OVMF Host Bridge DID Address