WatchdogTimer.c

/** @file
  Implementation of Watchdog Timer Architectural Protocol using UEFI APIs.

Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent

**/

#include "WatchdogTimer.h"

//
// Handle for the Watchdog Timer Architectural Protocol instance produced by this driver
//
EFI_HANDLE  mWatchdogTimerHandle = NULL;

//
// The Watchdog Timer Architectural Protocol instance produced by this driver
//
EFI_WATCHDOG_TIMER_ARCH_PROTOCOL  mWatchdogTimer = {
  WatchdogTimerDriverRegisterHandler,
  WatchdogTimerDriverSetTimerPeriod,
  WatchdogTimerDriverGetTimerPeriod
};

//
// The watchdog timer period in 100 ns units
//
UINT64  mWatchdogTimerPeriod = 0;

//
// The notification function to call if the watchdig timer fires
//
EFI_WATCHDOG_TIMER_NOTIFY  mWatchdogTimerNotifyFunction = NULL;

//
// The one-shot timer event that is armed when the watchdog timer is enabled
//
EFI_EVENT  mWatchdogTimerEvent;

/**
  Notification function that is called if the watchdog timer is fired.

  Notification function for the one-shot timer event that was signaled
  when the watchdog timer expired. If a handler has been registered with
  the Watchdog Timer Architectural Protocol, then that handler is called
  passing in the time period that has passed that cause the watchdog timer
  to fire.  Then, a call to the Runtime Service ResetSystem() is made to
  reset the platform.

  @param  Timer     The one-shot timer event that was signaled when the
                    watchdog timer expired.
  @param  Context   The context that was registered when the event Timer was created.

**/
VOID
EFIAPI
WatchdogTimerDriverExpires (
  IN EFI_EVENT  Timer,
  IN VOID       *Context
  )
{
  REPORT_STATUS_CODE (EFI_ERROR_CODE | EFI_ERROR_MINOR, (EFI_COMPUTING_UNIT_HOST_PROCESSOR | EFI_CU_HP_EC_TIMER_EXPIRED));

  //
  // If a notification function has been registered, then call it
  //
  if (mWatchdogTimerNotifyFunction != NULL) {
    mWatchdogTimerNotifyFunction (mWatchdogTimerPeriod);
  }

  DEBUG ((DEBUG_ERROR, "Watchdog Timer resetting system\n"));

  //
  // Reset the platform
  //
  gRT->ResetSystem (EfiResetCold, EFI_TIMEOUT, 0, NULL);
}

/**
  Registers a handler that is to be invoked when the watchdog timer fires.

  This function registers a handler that is to be invoked when the watchdog
  timer fires.  By default, the EFI_WATCHDOG_TIMER protocol will call the
  Runtime Service ResetSystem() when the watchdog timer fires.  If a
  NotifyFunction is registered, then the NotifyFunction will be called before
  the Runtime Service ResetSystem() is called.  If NotifyFunction is NULL, then
  the watchdog handler is unregistered.  If a watchdog handler is registered,
  then EFI_SUCCESS is returned.  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 uninstall a handler when a handler is not installed,
  then return EFI_INVALID_PARAMETER.

  @param  This                  The EFI_WATCHDOG_TIMER_ARCH_PROTOCOL instance.
  @param  NotifyFunction        The function to call when the watchdog timer fires.  If this
                                is NULL, then the handler will be unregistered.

  @retval EFI_SUCCESS           The watchdog timer handler was registered or unregistered.
  @retval EFI_ALREADY_STARTED   NotifyFunction is not NULL, and a handler is already registered.
  @retval EFI_INVALID_PARAMETER NotifyFunction is NULL, and a handler was not previously registered.

**/
EFI_STATUS
EFIAPI
WatchdogTimerDriverRegisterHandler (
  IN EFI_WATCHDOG_TIMER_ARCH_PROTOCOL  *This,
  IN EFI_WATCHDOG_TIMER_NOTIFY         NotifyFunction
  )
{
  //
  // If NotifyFunction is NULL, and a handler was not previously registered,
  // return EFI_INVALID_PARAMETER.
  //
  if ((NotifyFunction == NULL) && (mWatchdogTimerNotifyFunction == NULL)) {
    return EFI_INVALID_PARAMETER;
  }

  //
  // If NotifyFunction is not NULL, and a handler is already registered,
  // return EFI_ALREADY_STARTED.
  //
  if ((NotifyFunction != NULL) && (mWatchdogTimerNotifyFunction != NULL)) {
    return EFI_ALREADY_STARTED;
  }

  mWatchdogTimerNotifyFunction = NotifyFunction;

  return EFI_SUCCESS;
}

/**
  Sets the amount of time in the future to fire the watchdog timer.

  This function sets the amount of time to wait before firing the watchdog
  timer to TimerPeriod 100 ns 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 100 ns 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
                            100 ns units.
  @retval EFI_DEVICE_ERROR  A watchdog timer could not be programmed due to a device
                            error.

**/
EFI_STATUS
EFIAPI
WatchdogTimerDriverSetTimerPeriod (
  IN EFI_WATCHDOG_TIMER_ARCH_PROTOCOL  *This,
  IN UINT64                            TimerPeriod
  )
{
  mWatchdogTimerPeriod = TimerPeriod;

  return gBS->SetTimer (
                mWatchdogTimerEvent,
                (mWatchdogTimerPeriod == 0) ? TimerCancel : TimerRelative,
                mWatchdogTimerPeriod
                );
}

/**
  Retrieves the amount of time in 100 ns units that the system will wait before firing the watchdog timer.

  This function retrieves the amount of time the system will wait before firing
  the watchdog timer.  This period is returned in TimerPeriod, and EFI_SUCCESS
  is returned.  If TimerPeriod is NULL, then EFI_INVALID_PARAMETER is returned.

  @param  This                    The EFI_WATCHDOG_TIMER_ARCH_PROTOCOL instance.
  @param  TimerPeriod             A pointer to the amount of time in 100 ns units that the system
                                  will wait before the watchdog timer is fired.  If TimerPeriod of
                                  zero is returned, then the watchdog timer is disabled.

  @retval EFI_SUCCESS             The amount of time that the system will wait before
                                  firing the watchdog timer was returned in TimerPeriod.
  @retval EFI_INVALID_PARAMETER   TimerPeriod is NULL.

**/
EFI_STATUS
EFIAPI
WatchdogTimerDriverGetTimerPeriod (
  IN EFI_WATCHDOG_TIMER_ARCH_PROTOCOL  *This,
  IN UINT64                            *TimerPeriod
  )
{
  if (TimerPeriod == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  *TimerPeriod = mWatchdogTimerPeriod;

  return EFI_SUCCESS;
}

/**
  Entry point of the Watchdog Timer Architectural Protocol driver.

  @param  ImageHandle   The image handle of this driver.
  @param  SystemTable   The pointer of EFI_SYSTEM_TABLE.

  @retval EFI_SUCCESS   Watchdog Timer Architectural Protocol successfully installed.

**/
EFI_STATUS
EFIAPI
WatchdogTimerDriverInitialize (
  IN EFI_HANDLE        ImageHandle,
  IN EFI_SYSTEM_TABLE  *SystemTable
  )
{
  EFI_STATUS  Status;

  //
  // Make sure the Watchdog Timer Architectural Protocol has not been installed in the system yet.
  //
  ASSERT_PROTOCOL_ALREADY_INSTALLED (NULL, &gEfiWatchdogTimerArchProtocolGuid);

  //
  // Create the timer event to implement a simple watchdog timer
  //
  Status = gBS->CreateEvent (
                  EVT_TIMER | EVT_NOTIFY_SIGNAL,
                  TPL_NOTIFY,
                  WatchdogTimerDriverExpires,
                  NULL,
                  &mWatchdogTimerEvent
                  );
  ASSERT_EFI_ERROR (Status);

  //
  // Install the Watchdog Timer Arch Protocol onto a new handle
  //
  Status = gBS->InstallMultipleProtocolInterfaces (
                  &mWatchdogTimerHandle,
                  &gEfiWatchdogTimerArchProtocolGuid,
                  &mWatchdogTimer,
                  NULL
                  );
  ASSERT_EFI_ERROR (Status);

  return EFI_SUCCESS;
}