1 files changed, 98 insertions, 0 deletions
diff --git a/OvmfPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c b/OvmfPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c
new file mode 100644
index 0000000000..05b0257451
--- /dev/null
+++ b/OvmfPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c
@@ -0,0 +1,98 @@
+/** @file
+  Provide constructor and GetTick for Base instance of ACPI Timer Library
+
+  Copyright (C) 2014, Gabriel L. Somlo <somlo@cmu.edu>
+
+  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/DebugLib.h>
+#include <Library/IoLib.h>
+#include <Library/PciLib.h>
+#include <OvmfPlatforms.h>
+
+//
+// Power Management PCI Configuration Register fields
+//
+#define PMBA_RTE  BIT0
+
+//
+// Offset in the Power Management Base Address to the ACPI Timer
+//
+#define ACPI_TIMER_OFFSET  0x8
+
+//
+// Cached ACPI Timer IO Address
+//
+STATIC UINT32 mAcpiTimerIoAddr;
+
+/**
+  The constructor function caches the ACPI tick counter address
+
+  At the time this constructor runs (DXE_CORE or later), ACPI IO space
+  has already been enabled by either PlatformPei or by the "Base"
+  instance of this library.
+  In order to avoid querying the underlying platform type during each
+  tick counter read operation, we cache the counter address during
+  initialization of this instance of the Timer Library.
+
+  @retval EFI_SUCCESS   The constructor always returns RETURN_SUCCESS.
+
+**/
+RETURN_STATUS
+EFIAPI
+AcpiTimerLibConstructor (
+  VOID
+  )
+{
+  UINT16 HostBridgeDevId;
+  UINTN Pmba;
+
+  //
+  // Query Host Bridge DID to determine platform type
+  //
+  HostBridgeDevId = PciRead16 (OVMF_HOSTBRIDGE_DID);
+  switch (HostBridgeDevId) {
+    case INTEL_82441_DEVICE_ID:
+      Pmba = POWER_MGMT_REGISTER_PIIX4 (0x40);
+      break;
+    case INTEL_Q35_MCH_DEVICE_ID:
+      Pmba = POWER_MGMT_REGISTER_Q35 (0x40);
+      break;
+    default:
+      DEBUG ((EFI_D_ERROR, "%a: Unknown Host Bridge Device ID: 0x%04x\n",
+        __FUNCTION__, HostBridgeDevId));
+      ASSERT (FALSE);
+      return RETURN_UNSUPPORTED;
+  }
+
+  mAcpiTimerIoAddr = (PciRead32 (Pmba) & ~PMBA_RTE) + ACPI_TIMER_OFFSET;
+
+  return RETURN_SUCCESS;
+}
+
+/**
+  Internal function to read the current tick counter of ACPI.
+
+  Read the current ACPI tick counter using the counter address cached
+  by this instance's constructor.
+
+  @return The tick counter read.
+
+**/
+UINT32
+InternalAcpiGetTimerTick (
+  VOID
+  )
+{
+  //
+  //   Return the current ACPI timer value.
+  //
+  return IoRead32 (mAcpiTimerIoAddr);
+}