[edk2-platforms][PATCH 03/34] Platform/Ampere: Add FailSafe and WDT support

["Nhi Pham" <nhi@os.amperecomputing.com>]

The FailSafeDxe driver supports to revert the system's configuration to
last good values if the system fails to boot up multiple times. It also
implements the Watchdog Timer Architectural Protocol to reset the system
if it hangs.

By default, when system starts, it configures the secure watchdog timer
with a default value of 5 minutes. If the system boots up cleanly to a
considered good stage, the counter is cleared as it indicates FailSafe
monitor (ATF) that the system boots up successfully. If the system boots
up with failure, it will be restarted right after the timer expires.

Signed-off-by: Nhi Pham <nhi@os.amperecomputing.com>
---
 Silicon/Ampere/AmpereAltraPkg/Ac01Pkg.dsc.inc       |   1 -
 Platform/Ampere/JadePkg/Jade.dsc                    |   8 +
 Platform/Ampere/JadePkg/Jade.fdf                    |   6 +-
 Platform/Ampere/Drivers/FailSafeDxe/FailSafeDxe.inf |  54 +++
 Platform/Ampere/Drivers/FailSafeDxe/FailSafe.h      |  18 +
 Platform/Ampere/Drivers/FailSafeDxe/Watchdog.h      |  29 ++
 Platform/Ampere/Drivers/FailSafeDxe/FailSafeDxe.c   | 177 ++++++++++
 Platform/Ampere/Drivers/FailSafeDxe/Watchdog.c      | 355 ++++++++++++++++++++
 8 files changed, 646 insertions(+), 2 deletions(-)

diff --git a/Silicon/Ampere/AmpereAltraPkg/Ac01Pkg.dsc.inc b/Silicon/Ampere/AmpereAltraPkg/Ac01Pkg.dsc.inc
index 4ee79342283b..f2422156d1c3 100755
--- a/Silicon/Ampere/AmpereAltraPkg/Ac01Pkg.dsc.inc
+++ b/Silicon/Ampere/AmpereAltraPkg/Ac01Pkg.dsc.inc
@@ -578,7 +578,6 @@ [Components.common]
   # Timer
   #
   ArmPkg/Drivers/TimerDxe/TimerDxe.inf
-  MdeModulePkg/Universal/WatchdogTimerDxe/WatchdogTimer.inf
 
   #
   # ARM GIC Dxe
diff --git a/Platform/Ampere/JadePkg/Jade.dsc b/Platform/Ampere/JadePkg/Jade.dsc
index c14bb62e02e8..56c6d53e3629 100755
--- a/Platform/Ampere/JadePkg/Jade.dsc
+++ b/Platform/Ampere/JadePkg/Jade.dsc
@@ -49,6 +49,10 @@ [Defines]
 #
 ################################################################################
 [LibraryClasses]
+  #
+  # Library for FailSafe support
+  #
+  FailSafeLib|Platform/Ampere/Library/FailSafeLib/FailSafeLib.inf
 
 ################################################################################
 #
@@ -83,3 +87,7 @@ [PcdsPatchableInModule]
 #
 ################################################################################
 [Components.common]
+  #
+  # FailSafe and Watchdog Timer
+  #
+  Platform/Ampere/Drivers/FailSafeDxe/FailSafeDxe.inf
diff --git a/Platform/Ampere/JadePkg/Jade.fdf b/Platform/Ampere/JadePkg/Jade.fdf
index db6a6abf0359..0e97a5e30186 100755
--- a/Platform/Ampere/JadePkg/Jade.fdf
+++ b/Platform/Ampere/JadePkg/Jade.fdf
@@ -199,7 +199,11 @@ [FV.FvMain]
   # Timer
   #
   INF ArmPkg/Drivers/TimerDxe/TimerDxe.inf
-  INF MdeModulePkg/Universal/WatchdogTimerDxe/WatchdogTimer.inf
+
+  #
+  # FailSafe and Watchdog Timer
+  #
+  INF Platform/Ampere/Drivers/FailSafeDxe/FailSafeDxe.inf
 
   #
   # ARM GIC Dxe
diff --git a/Platform/Ampere/Drivers/FailSafeDxe/FailSafeDxe.inf b/Platform/Ampere/Drivers/FailSafeDxe/FailSafeDxe.inf
new file mode 100755
index 000000000000..e7ffa07d8a14
--- /dev/null
+++ b/Platform/Ampere/Drivers/FailSafeDxe/FailSafeDxe.inf
@@ -0,0 +1,54 @@
+## @file
+#
+# Copyright (c) 2020, Ampere Computing LLC. All rights reserved.<BR>
+#
+# SPDX-License-Identifier: BSD-2-Clause-Patent
+#
+##
+
+[Defines]
+  INF_VERSION                    = 0x0001001B
+  BASE_NAME                      = FailSafeDxe
+  FILE_GUID                      = 7BC4F970-B1CF-11E6-80F5-76304DEC7EB7
+  MODULE_TYPE                    = DXE_DRIVER
+  VERSION_STRING                 = 1.0
+  ENTRY_POINT                    = FailSafeDxeEntryPoint
+
+[Sources]
+  FailSafe.h
+  FailSafeDxe.c
+  Watchdog.h
+  Watchdog.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+  MdeModulePkg/MdeModulePkg.dec
+  EmbeddedPkg/EmbeddedPkg.dec
+  ArmPkg/ArmPkg.dec
+  ArmPlatformPkg/ArmPlatformPkg.dec
+  Silicon/Ampere/AmperePkg.dec
+  Silicon/Ampere/AmpereAltraPkg/Ac01Pkg.dec
+  Platform/Ampere/AmperePkg.dec
+
+[LibraryClasses]
+  UefiDriverEntryPoint
+  UefiLib
+  PcdLib
+  ArmSmcLib
+  UefiBootServicesTableLib
+  UefiRuntimeServicesTableLib
+  DebugLib
+  NVParamLib
+  FailSafeLib
+  TimerLib
+
+[Pcd]
+  gArmTokenSpaceGuid.PcdGenericWatchdogControlBase
+  gArmTokenSpaceGuid.PcdGenericWatchdogEl2IntrNum
+
+[Protocols]
+  gEfiWatchdogTimerArchProtocolGuid             ## PRODUCES
+  gHardwareInterrupt2ProtocolGuid               ## CONSUMES
+
+[Depex]
+  gHardwareInterrupt2ProtocolGuid
diff --git a/Platform/Ampere/Drivers/FailSafeDxe/FailSafe.h b/Platform/Ampere/Drivers/FailSafeDxe/FailSafe.h
new file mode 100755
index 000000000000..642156933e9f
--- /dev/null
+++ b/Platform/Ampere/Drivers/FailSafeDxe/FailSafe.h
@@ -0,0 +1,18 @@
+/** @file
+
+  Copyright (c) 2020, Ampere Computing LLC. All rights reserved.<BR>
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#ifndef _FAILSAFE_H_
+#define _FAILSAFE_H_
+
+#include <Uefi.h>
+
+BOOLEAN
+EFIAPI
+IsFailSafeOff (VOID);
+
+#endif /* _FAILSAFE_H_ */
diff --git a/Platform/Ampere/Drivers/FailSafeDxe/Watchdog.h b/Platform/Ampere/Drivers/FailSafeDxe/Watchdog.h
new file mode 100755
index 000000000000..467131af50d6
--- /dev/null
+++ b/Platform/Ampere/Drivers/FailSafeDxe/Watchdog.h
@@ -0,0 +1,29 @@
+/** @file
+
+  Copyright (c) 2020, Ampere Computing LLC. All rights reserved.<BR>
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#ifndef _GENERIC_WATCHDOG_H_
+#define _GENERIC_WATCHDOG_H_
+
+#include <Protocol/WatchdogTimer.h>
+
+/* The number of 100ns periods (the unit of time passed to these functions)
+   in a second */
+#define TIME_UNITS_PER_SECOND           10000000
+
+/**
+  The function to install Watchdog timer protocol to the system
+
+  @retval  Return         EFI_SUCCESS if install Watchdog timer protocol successfully.
+ **/
+EFI_STATUS
+EFIAPI
+WatchdogTimerInstallProtocol (
+  EFI_WATCHDOG_TIMER_ARCH_PROTOCOL **WatchdogTimerProtocol
+  );
+
+#endif /* _GENERIC_WATCHDOG_H_ */
diff --git a/Platform/Ampere/Drivers/FailSafeDxe/FailSafeDxe.c b/Platform/Ampere/Drivers/FailSafeDxe/FailSafeDxe.c
new file mode 100755
index 000000000000..954da9ffb102
--- /dev/null
+++ b/Platform/Ampere/Drivers/FailSafeDxe/FailSafeDxe.c
@@ -0,0 +1,177 @@
+/** @file
+
+  Copyright (c) 2020, Ampere Computing LLC. All rights reserved.<BR>
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include <Uefi.h>
+#include <Library/ArmSmcLib.h>
+#include <Library/BaseLib.h>
+#include <Library/DebugLib.h>
+#include <Guid/EventGroup.h>
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/UefiRuntimeServicesTableLib.h>
+#include <Library/UefiLib.h>
+#include <Library/NVParamLib.h>
+#include <Library/FailSafeLib.h>
+
+#include "FailSafe.h"
+#include "Watchdog.h"
+
+STATIC UINTN                              gWatchdogOSTimeout;
+STATIC BOOLEAN                            gFailSafeOff;
+STATIC EFI_WATCHDOG_TIMER_ARCH_PROTOCOL   *gWatchdogTimer;
+
+EFI_STATUS
+EFIAPI
+FailSafeTestBootFailure (VOID);
+
+STATIC VOID
+FailSafeTurnOff (VOID)
+{
+  EFI_STATUS  Status;
+
+  if (IsFailSafeOff ()) {
+    return;
+  }
+
+  Status = FailSafeBootSuccessfully ();
+  ASSERT_EFI_ERROR (Status);
+
+  gFailSafeOff = TRUE;
+
+  /* Disable Watchdog timer */
+  gWatchdogTimer->SetTimerPeriod (gWatchdogTimer, 0);
+}
+
+BOOLEAN
+EFIAPI
+IsFailSafeOff (VOID)
+{
+  return gFailSafeOff;
+}
+
+/**
+  The function to disable Watchdog timer when enter Setup screen
+ **/
+VOID
+WdtTimerEnterSetupScreenCallback (
+  IN EFI_EVENT  Event,
+  IN VOID       *Context
+  )
+{
+  /* Make sure FailSafe is turned off */
+  FailSafeTurnOff ();
+}
+
+/**
+  The function to refresh Watchdog timer in the event before booting
+ **/
+VOID
+WdtTimerBeforeBootCallback (
+  IN EFI_EVENT  Event,
+  IN VOID       *Context
+  )
+{
+  /*
+   * At this point, the system is considered boot successfully to BIOS
+   */
+  FailSafeTurnOff ();
+
+  /*
+   * It is BIOS's responsibility to setup Watchdog when load an EFI application
+   * after this step
+   */
+}
+
+/**
+  The function to refresh Watchdog timer in the event before exiting boot services
+ **/
+VOID
+WdtTimerExitBootServiceCallback (
+  IN EFI_EVENT  Event,
+  IN VOID       *Context
+  )
+{
+
+  /* Enable Watchdog timer for OS booting */
+  if (gWatchdogOSTimeout != 0) {
+    gWatchdogTimer->SetTimerPeriod (
+                      gWatchdogTimer,
+                      gWatchdogOSTimeout * TIME_UNITS_PER_SECOND
+                      );
+  } else {
+    /* Disable Watchdog timer */
+    gWatchdogTimer->SetTimerPeriod (gWatchdogTimer, 0);
+  }
+}
+
+/**
+  This function is a hook called when user loads the manufacturing
+  or optimal defaults.
+
+  @param Defaults : (NVRAM_VARIABLE *)optimal or manufacturing
+  @Data           : Messagebox
+
+  @retval VOID
+**/
+VOID
+LoadNVRAMDefaultConfig (
+  IN VOID   *Defaults,
+  IN UINTN  Data
+  )
+{
+  NVParamClrAll ();
+}
+
+/**
+  Main entry for this driver.
+
+  @param ImageHandle     Image handle this driver.
+  @param SystemTable     Pointer to SystemTable.
+
+  @retval EFI_SUCESS     This function always complete successfully.
+
+**/
+EFI_STATUS
+EFIAPI
+FailSafeDxeEntryPoint (
+  IN EFI_HANDLE         ImageHandle,
+  IN EFI_SYSTEM_TABLE   *SystemTable
+  )
+{
+  EFI_EVENT                 ExitBootServicesEvent;
+  EFI_STATUS                Status;
+
+  gFailSafeOff = FALSE;
+
+  FailSafeTestBootFailure ();
+
+  /* We need to setup non secure Watchdog to ensure that the system will
+   * boot to OS successfully.
+   *
+   * The BIOS doesn't handle Watchdog interrupt so we expect WS1 asserted EL3
+   * when Watchdog timeout triggered
+   */
+
+  Status = WatchdogTimerInstallProtocol (&gWatchdogTimer);
+  ASSERT_EFI_ERROR (Status);
+
+  // FIXME: We should register a callback function before entering to Setup screen
+  // rather than always call it at DXE phase.
+  FailSafeTurnOff ();
+
+  /* Register event before exit boot services */
+  Status = gBS->CreateEvent (
+                  EVT_SIGNAL_EXIT_BOOT_SERVICES,
+                  TPL_NOTIFY,
+                  WdtTimerExitBootServiceCallback,
+                  NULL,
+                  &ExitBootServicesEvent
+                  );
+  ASSERT_EFI_ERROR (Status);
+
+  return Status;
+}
diff --git a/Platform/Ampere/Drivers/FailSafeDxe/Watchdog.c b/Platform/Ampere/Drivers/FailSafeDxe/Watchdog.c
new file mode 100755
index 000000000000..363ee85d714b
--- /dev/null
+++ b/Platform/Ampere/Drivers/FailSafeDxe/Watchdog.c
@@ -0,0 +1,355 @@
+/** @file
+
+  Copyright (c) 2020, Ampere Computing LLC. All rights reserved.<BR>
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include <Library/ArmLib.h>
+#include <Library/ArmGenericTimerCounterLib.h>
+#include <Library/BaseLib.h>
+#include <Library/DebugLib.h>
+#include <Library/PcdLib.h>
+#include <Library/IoLib.h>
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/UefiRuntimeServicesTableLib.h>
+#include <Protocol/HardwareInterrupt2.h>
+
+#include "FailSafe.h"
+#include "Watchdog.h"
+
+/* Watchdog timer controller registers */
+#define WDT_CTRL_BASE_REG                     FixedPcdGet64 (PcdGenericWatchdogControlBase)
+#define WDT_CTRL_WCS_OFF                      0x0
+#define WDT_CTRL_WCS_ENABLE_MASK              0x1
+#define WDT_CTRL_WOR_OFF                      0x8
+#define WDT_CTRL_WCV_OFF                      0x10
+#define WS0_INTERRUPT_SOURCE                  FixedPcdGet32 (PcdGenericWatchdogEl2IntrNum)
+
+STATIC UINT64                                 mNumTimerTicks;
+STATIC EFI_HARDWARE_INTERRUPT2_PROTOCOL       *mInterruptProtocol;
+BOOLEAN                                       mInterruptWS0Enabled;
+
+STATIC
+VOID
+WatchdogTimerWriteOffsetRegister (
+  UINT32  Value
+  )
+{
+  MmioWrite32 (WDT_CTRL_BASE_REG + WDT_CTRL_WOR_OFF, Value);
+}
+
+STATIC
+VOID
+WatchdogTimerWriteCompareRegister (
+  UINT64  Value
+  )
+{
+  MmioWrite64 (WDT_CTRL_BASE_REG + WDT_CTRL_WCV_OFF, Value);
+}
+
+STATIC
+EFI_STATUS
+WatchdogTimerEnable (
+  IN BOOLEAN Enable
+  )
+{
+  UINT32 Val =  MmioRead32 ((UINTN) (WDT_CTRL_BASE_REG + WDT_CTRL_WCS_OFF));
+
+  if (Enable) {
+    Val |= WDT_CTRL_WCS_ENABLE_MASK;
+  } else {
+    Val &= ~WDT_CTRL_WCS_ENABLE_MASK;
+  }
+  MmioWrite32 ((UINTN) (WDT_CTRL_BASE_REG + WDT_CTRL_WCS_OFF), Val);
+
+  return EFI_SUCCESS;
+}
+
+STATIC
+EFI_STATUS
+WatchdogTimerSetup (VOID)
+{
+  EFI_STATUS  Status;
+
+  /* Disable Watchdog timer */
+  WatchdogTimerEnable (FALSE);
+
+  if (!mInterruptWS0Enabled) {
+    Status = mInterruptProtocol->EnableInterruptSource (
+                                   mInterruptProtocol,
+                                   WS0_INTERRUPT_SOURCE
+                                   );
+    ASSERT_EFI_ERROR (Status);
+
+    mInterruptWS0Enabled = TRUE;
+  }
+
+  if (mNumTimerTicks == 0) {
+    return EFI_SUCCESS;
+  }
+
+  /* If the number of required ticks is greater than the max the Watchdog's
+     offset register (WOR) can hold, we need to manually compute and set
+     the compare register (WCV) */
+  if (mNumTimerTicks > MAX_UINT32) {
+    /* We need to enable the Watchdog *before* writing to the compare register,
+       because enabling the Watchdog causes an "explicit refresh", which
+       clobbers the compare register (WCV). In order to make sure this doesn't
+       trigger an interrupt, set the offset to max. */
+    WatchdogTimerWriteOffsetRegister (MAX_UINT32);
+    WatchdogTimerEnable (TRUE);
+    WatchdogTimerWriteCompareRegister (ArmGenericTimerGetSystemCount () + mNumTimerTicks);
+  } else {
+    WatchdogTimerWriteOffsetRegister ((UINT32) mNumTimerTicks);
+    WatchdogTimerEnable (TRUE);
+  }
+
+  return EFI_SUCCESS;
+}
+
+
+/* This function is called when the Watchdog's first signal (WS0) goes high.
+   It uses the ResetSystem Runtime Service to reset the board.
+*/
+VOID
+EFIAPI
+WatchdogTimerInterruptHandler (
+  IN  HARDWARE_INTERRUPT_SOURCE   Source,
+  IN  EFI_SYSTEM_CONTEXT          SystemContext
+  )
+{
+  STATIC CONST CHAR16 ResetString[]= L"The generic Watchdog timer ran out.";
+
+  mInterruptProtocol->EndOfInterrupt (mInterruptProtocol, Source);
+
+  if (!IsFailSafeOff ()) {
+    /* Not handling interrupt as ATF is monitoring it */
+    return;
+  }
+
+  WatchdogTimerEnable (FALSE);
+
+  gRT->ResetSystem (
+         EfiResetCold,
+         EFI_TIMEOUT,
+         StrSize (ResetString),
+         (VOID *) &ResetString
+         );
+
+  /* If we got here then the reset didn't work */
+  ASSERT (FALSE);
+}
+
+/**
+  This function registers the handler NotifyFunction so it is called every time
+  the Watchdog timer expires.  It also passes the amount of time since the last
+  handler call to the NotifyFunction.
+  If NotifyFunction is not NULL and a handler is not already registered,
+  then the new handler is registered and EFI_SUCCESS is returned.
+  If NotifyFunction is NULL, and a handler is already registered,
+  then that handler is unregistered.
+  If an attempt is made to register a handler when a handler is already
+  registered, then EFI_ALREADY_STARTED is returned.
+  If an attempt is made to unregister a handler when a handler is not
+  registered, then EFI_INVALID_PARAMETER is returned.
+
+  @param  This             The EFI_TIMER_ARCH_PROTOCOL instance.
+  @param  NotifyFunction   The function to call when a timer interrupt fires.
+                           This function executes at TPL_HIGH_LEVEL. The DXE
+                           Core will register a handler for the timer interrupt,
+                           so it can know how much time has passed. This
+                           information is used to signal timer based events.
+                           NULL will unregister the handler.
+
+  @retval EFI_UNSUPPORTED       The code does not support NotifyFunction.
+
+**/
+EFI_STATUS
+EFIAPI
+WatchdogTimerRegisterHandler (
+  IN CONST EFI_WATCHDOG_TIMER_ARCH_PROTOCOL   *This,
+  IN EFI_WATCHDOG_TIMER_NOTIFY                NotifyFunction
+  )
+{
+  /* Not support. Watchdog will reset the board */
+  return EFI_UNSUPPORTED;
+}
+
+/**
+  This function sets the amount of time to wait before firing the Watchdog
+  timer to TimerPeriod 100ns units.  If TimerPeriod is 0, then the Watchdog
+  timer is disabled.
+
+  @param  This             The EFI_WATCHDOG_TIMER_ARCH_PROTOCOL instance.
+  @param  TimerPeriod      The amount of time in 100ns units to wait before
+                           the Watchdog timer is fired. If TimerPeriod is zero,
+                           then the Watchdog timer is disabled.
+
+  @retval EFI_SUCCESS           The Watchdog timer has been programmed to fire
+                                in Time  100ns units.
+  @retval EFI_DEVICE_ERROR      A Watchdog timer could not be programmed due
+                                to a device error.
+
+**/
+EFI_STATUS
+EFIAPI
+WatchdogTimerSetPeriod (
+  IN CONST EFI_WATCHDOG_TIMER_ARCH_PROTOCOL   *This,
+  IN UINT64                                   TimerPeriod   // In 100ns units
+  )
+{
+  mNumTimerTicks  = (ArmGenericTimerGetTimerFreq () * TimerPeriod) / TIME_UNITS_PER_SECOND;
+
+  if (!IsFailSafeOff ()) {
+    /* Not support Watchdog timer service until FailSafe is off as ATF is monitoring it */
+    return EFI_SUCCESS;
+  }
+
+  return WatchdogTimerSetup ();
+}
+
+/**
+  This function retrieves the period of timer interrupts in 100ns units,
+  returns that value in TimerPeriod, and returns EFI_SUCCESS.  If TimerPeriod
+  is NULL, then EFI_INVALID_PARAMETER is returned.  If a TimerPeriod of 0 is
+  returned, then the timer is currently disabled.
+
+  @param  This             The EFI_TIMER_ARCH_PROTOCOL instance.
+  @param  TimerPeriod      A pointer to the timer period to retrieve in
+                           100ns units. If 0 is returned, then the timer is
+                           currently disabled.
+
+
+  @retval EFI_SUCCESS           The timer period was returned in TimerPeriod.
+  @retval EFI_INVALID_PARAMETER TimerPeriod is NULL.
+
+**/
+EFI_STATUS
+EFIAPI
+WatchdogTimerGetPeriod (
+  IN CONST EFI_WATCHDOG_TIMER_ARCH_PROTOCOL   *This,
+  OUT UINT64                                  *TimerPeriod
+  )
+{
+  if (TimerPeriod == NULL) {
+    return EFI_INVALID_PARAMETER;
+  }
+
+  *TimerPeriod = ((TIME_UNITS_PER_SECOND / ArmGenericTimerGetTimerFreq ()) * mNumTimerTicks);
+
+  return EFI_SUCCESS;
+}
+
+/**
+  Interface structure for the Watchdog Architectural Protocol.
+
+  @par Protocol Description:
+  This protocol provides a service to set the amount of time to wait
+  before firing the Watchdog timer, and it also provides a service to
+  register a handler that is invoked when the Watchdog timer fires.
+
+  @par When the Watchdog timer fires, control will be passed to a handler
+  if one has been registered.  If no handler has been registered,
+  or the registered handler returns, then the system will be
+  reset by calling the Runtime Service ResetSystem().
+
+  @param RegisterHandler
+  Registers a handler that will be called each time the
+  Watchdogtimer interrupt fires.  TimerPeriod defines the minimum
+  time between timer interrupts, so TimerPeriod will also
+  be the minimum time between calls to the registered
+  handler.
+  NOTE: If the Watchdog resets the system in hardware, then
+        this function will not have any chance of executing.
+
+  @param SetTimerPeriod
+  Sets the period of the timer interrupt in 100ns units.
+  This function is optional, and may return EFI_UNSUPPORTED.
+  If this function is supported, then the timer period will
+  be rounded up to the nearest supported timer period.
+
+  @param GetTimerPeriod
+  Retrieves the period of the timer interrupt in 100ns units.
+
+**/
+STATIC EFI_WATCHDOG_TIMER_ARCH_PROTOCOL gWatchdogTimer = {
+  (EFI_WATCHDOG_TIMER_REGISTER_HANDLER)  WatchdogTimerRegisterHandler,
+  (EFI_WATCHDOG_TIMER_SET_TIMER_PERIOD)  WatchdogTimerSetPeriod,
+  (EFI_WATCHDOG_TIMER_GET_TIMER_PERIOD)  WatchdogTimerGetPeriod
+};
+
+EFI_STATUS
+EFIAPI
+WatchdogTimerInstallProtocol (
+  EFI_WATCHDOG_TIMER_ARCH_PROTOCOL **WatchdogTimerProtocol
+  )
+{
+  EFI_STATUS      Status;
+  EFI_HANDLE      Handle;
+  EFI_TPL         CurrentTpl;
+
+  /* Make sure the Watchdog Timer Architectural Protocol has not been installed
+     in the system yet.
+     This will avoid conflicts with the universal Watchdog */
+  ASSERT_PROTOCOL_ALREADY_INSTALLED (NULL, &gEfiWatchdogTimerArchProtocolGuid);
+
+  ASSERT (ArmGenericTimerGetTimerFreq () != 0);
+
+  /* Install interrupt handler */
+  Status = gBS->LocateProtocol (
+                  &gHardwareInterrupt2ProtocolGuid,
+                  NULL,
+                  (VOID **)&mInterruptProtocol
+                  );
+  ASSERT_EFI_ERROR (Status);
+
+  /*
+   * We don't want to be interrupted while registering Watchdog interrupt source as the interrupt
+   * may be trigger in the middle because the interrupt line already enabled in the EL3.
+   */
+  CurrentTpl = gBS->RaiseTPL (TPL_HIGH_LEVEL);
+
+  Status = mInterruptProtocol->RegisterInterruptSource (
+                                 mInterruptProtocol,
+                                 WS0_INTERRUPT_SOURCE,
+                                 WatchdogTimerInterruptHandler
+                                 );
+  ASSERT_EFI_ERROR (Status);
+
+  /* Don't enable interrupt until FailSafe off */
+  mInterruptWS0Enabled = FALSE;
+  Status = mInterruptProtocol->DisableInterruptSource (
+                                 mInterruptProtocol,
+                                 WS0_INTERRUPT_SOURCE
+                                 );
+  ASSERT_EFI_ERROR (Status);
+
+  gBS->RestoreTPL (CurrentTpl);
+
+  Status = mInterruptProtocol->SetTriggerType (
+                                 mInterruptProtocol,
+                                 WS0_INTERRUPT_SOURCE,
+                                 EFI_HARDWARE_INTERRUPT2_TRIGGER_LEVEL_HIGH
+                                 );
+  ASSERT_EFI_ERROR (Status);
+
+  /* Install the Timer Architectural Protocol onto a new handle */
+  Handle = NULL;
+  Status = gBS->InstallMultipleProtocolInterfaces (
+                  &Handle,
+                  &gEfiWatchdogTimerArchProtocolGuid,
+                  &gWatchdogTimer,
+                  NULL
+                  );
+  ASSERT_EFI_ERROR (Status);
+
+  mNumTimerTicks = 0;
+
+  if (WatchdogTimerProtocol != NULL) {
+    *WatchdogTimerProtocol = &gWatchdogTimer;
+  }
+
+  return Status;
+}
-- 
2.17.1