GenericWatchdogDxe.c

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#include <PiDxe.h>
 
#include <Library/BaseLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/DebugLib.h>
#include <Library/IoLib.h>
#include <Library/PcdLib.h>
#include <Library/UefiBootServicesTableLib.h>
#include <Library/UefiRuntimeServicesTableLib.h>
#include <Library/UefiLib.h>
#include <Library/ArmGenericTimerCounterLib.h>
 
#include <Protocol/HardwareInterrupt2.h>
#include <Protocol/WatchdogTimer.h>
 
#include "GenericWatchdog.h"
 
/* The number of 100ns periods (the unit of time passed to these functions)
   in a second */
#define TIME_UNITS_PER_SECOND  10000000
 
/* In cases where the compare register was set manually, information about
   how long the watchdog was asked to wait cannot be retrieved from hardware.
   It is therefore stored here. 0 means the timer is not running. */
STATIC UINT64  mTimerPeriod = 0;
 
/* disables watchdog interaction after Exit Boot Services */
STATIC BOOLEAN  mExitedBootServices = FALSE;
 
#define MAX_UINT48  0xFFFFFFFFFFFFULL
 
STATIC EFI_HARDWARE_INTERRUPT2_PROTOCOL  *mInterruptProtocol;
STATIC EFI_WATCHDOG_TIMER_NOTIFY         mWatchdogNotify;
STATIC EFI_EVENT                         mEfiExitBootServicesEvent;
 
STATIC
UINT64
GetMaxWatchdogOffsetRegisterValue (
  VOID
  )
{
  UINT64  MaxWatchdogOffsetValue;
  UINT32  WatchdogIId;
  UINT8   WatchdogArchRevision;
 
  WatchdogIId          = MmioRead32 (GENERIC_WDOG_IID_REG);
  WatchdogArchRevision = (WatchdogIId >> GENERIC_WDOG_IID_ARCH_REV_SHIFT) & GENERIC_WDOG_IID_ARCH_REV_MASK;
 
  if (WatchdogArchRevision == 0) {
    MaxWatchdogOffsetValue = MAX_UINT32;
  } else {
    MaxWatchdogOffsetValue = MAX_UINT48;
  }
 
  return MaxWatchdogOffsetValue;
}
 
STATIC
VOID
WatchdogWriteOffsetRegister (
  UINT64  Value
  )
{
  MmioWrite32 (GENERIC_WDOG_OFFSET_REG_LOW, Value & MAX_UINT32);
  if (GetMaxWatchdogOffsetRegisterValue () == MAX_UINT48) {
    MmioWrite32 (GENERIC_WDOG_OFFSET_REG_HIGH, (Value >> 32) & MAX_UINT16);
  }
}
 
STATIC
VOID
WatchdogWriteCompareRegister (
  UINT64  Value
  )
{
  MmioWrite32 (GENERIC_WDOG_COMPARE_VALUE_REG_LOW, Value & MAX_UINT32);
  MmioWrite32 (GENERIC_WDOG_COMPARE_VALUE_REG_HIGH, (Value >> 32) & MAX_UINT32);
}
 
STATIC
VOID
WatchdogEnable (
  VOID
  )
{
  MmioWrite32 (GENERIC_WDOG_CONTROL_STATUS_REG, GENERIC_WDOG_ENABLED);
}
 
STATIC
VOID
WatchdogDisable (
  VOID
  )
{
  MmioWrite32 (GENERIC_WDOG_CONTROL_STATUS_REG, GENERIC_WDOG_DISABLED);
}
 
STATIC
VOID
EFIAPI
WatchdogExitBootServicesEvent (
  IN EFI_EVENT  Event,
  IN VOID       *Context
  )
{
  WatchdogDisable ();
  mTimerPeriod        = 0;
  mExitedBootServices = TRUE;
}
 
/* This function is called when the watchdog's first signal (WS0) goes high.
   It uses the ResetSystem Runtime Service to reset the board.
*/
STATIC
VOID
EFIAPI
WatchdogInterruptHandler (
  IN  HARDWARE_INTERRUPT_SOURCE  Source,
  IN  EFI_SYSTEM_CONTEXT         SystemContext
  )
{
  STATIC CONST CHAR16  ResetString[] = L"The generic watchdog timer ran out.";
 
  WatchdogDisable ();
 
  mInterruptProtocol->EndOfInterrupt (mInterruptProtocol, Source);
 
  //
  // The notify function should be called with the elapsed number of ticks
  // since the watchdog was armed, which should exceed the timer period.
  // We don't actually know the elapsed number of ticks, so let's return
  // the timer period plus 1.
  //
  if (mWatchdogNotify != NULL) {
    mWatchdogNotify (mTimerPeriod + 1);
  }
 
  gRT->ResetSystem (
         EfiResetCold,
         EFI_TIMEOUT,
         StrSize (ResetString),
         (CHAR16 *)ResetString
         );
 
  // If we got here then the reset didn't work
  ASSERT (FALSE);
}
 
STATIC
EFI_STATUS
EFIAPI
WatchdogRegisterHandler (
  IN EFI_WATCHDOG_TIMER_ARCH_PROTOCOL  *This,
  IN EFI_WATCHDOG_TIMER_NOTIFY         NotifyFunction
  )
{
  if ((mWatchdogNotify == NULL) && (NotifyFunction == NULL)) {
    return EFI_INVALID_PARAMETER;
  }
 
  if ((mWatchdogNotify != NULL) && (NotifyFunction != NULL)) {
    return EFI_ALREADY_STARTED;
  }
 
  mWatchdogNotify = NotifyFunction;
  return EFI_SUCCESS;
}
 
STATIC
EFI_STATUS
EFIAPI
WatchdogSetTimerPeriod (
  IN EFI_WATCHDOG_TIMER_ARCH_PROTOCOL  *This,
  IN UINT64                            TimerPeriod          // In 100ns units
  )
{
  UINTN   SystemCount;
  UINT64  MaxWatchdogOffsetValue;
  UINT64  TimerFrequencyHz;
  UINT64  NumTimerTicks;
 
  // If we've exited Boot Services but TimerPeriod isn't zero, this
  // indicates that the caller is doing something wrong.
  if (mExitedBootServices && (TimerPeriod != 0)) {
    mTimerPeriod = 0;
    WatchdogDisable ();
    return EFI_DEVICE_ERROR;
  }
 
  // If TimerPeriod is 0 this is a request to stop the watchdog.
  if (TimerPeriod == 0) {
    mTimerPeriod = 0;
    WatchdogDisable ();
    return EFI_SUCCESS;
  }
 
  // Work out how many timer ticks will equate to TimerPeriod
  TimerFrequencyHz = ArmGenericTimerGetTimerFreq ();
  ASSERT (TimerFrequencyHz != 0);
  mTimerPeriod  = TimerPeriod;
  NumTimerTicks = (TimerFrequencyHz * TimerPeriod) / TIME_UNITS_PER_SECOND;
 
  /* 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) */
  MaxWatchdogOffsetValue = GetMaxWatchdogOffsetRegisterValue ();
  if (NumTimerTicks > MaxWatchdogOffsetValue) {
    /* 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. */
    WatchdogWriteOffsetRegister (MaxWatchdogOffsetValue);
    WatchdogEnable ();
    SystemCount = ArmGenericTimerGetSystemCount ();
    WatchdogWriteCompareRegister (SystemCount + NumTimerTicks);
  } else {
    WatchdogWriteOffsetRegister (NumTimerTicks);
    WatchdogEnable ();
  }
 
  return EFI_SUCCESS;
}
 
STATIC
EFI_STATUS
EFIAPI
WatchdogGetTimerPeriod (
  IN EFI_WATCHDOG_TIMER_ARCH_PROTOCOL  *This,
  OUT UINT64                           *TimerPeriod
  )
{
  if (TimerPeriod == NULL) {
    return EFI_INVALID_PARAMETER;
  }
 
  *TimerPeriod = mTimerPeriod;
 
  return EFI_SUCCESS;
}
 
STATIC EFI_WATCHDOG_TIMER_ARCH_PROTOCOL  mWatchdogTimer = {
  WatchdogRegisterHandler,
  WatchdogSetTimerPeriod,
  WatchdogGetTimerPeriod
};
 
EFI_STATUS
EFIAPI
GenericWatchdogEntry (
  IN EFI_HANDLE        ImageHandle,
  IN EFI_SYSTEM_TABLE  *SystemTable
  )
{
  EFI_STATUS  Status;
  EFI_HANDLE  Handle;
 
  Status = gBS->LocateProtocol (
                  &gHardwareInterrupt2ProtocolGuid,
                  NULL,
                  (VOID **)&mInterruptProtocol
                  );
  ASSERT_EFI_ERROR (Status);
 
  /* 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);
 
  // Install interrupt handler
  Status = mInterruptProtocol->RegisterInterruptSource (
                                 mInterruptProtocol,
                                 FixedPcdGet32 (PcdGenericWatchdogEl2IntrNum),
                                 WatchdogInterruptHandler
                                 );
  if (EFI_ERROR (Status)) {
    return Status;
  }
 
  Status = mInterruptProtocol->SetTriggerType (
                                 mInterruptProtocol,
                                 FixedPcdGet32 (PcdGenericWatchdogEl2IntrNum),
                                 EFI_HARDWARE_INTERRUPT2_TRIGGER_EDGE_RISING
                                 );
  if (EFI_ERROR (Status)) {
    goto UnregisterHandler;
  }
 
  WatchdogDisable ();
 
  // Install the Timer Architectural Protocol onto a new handle
  Handle = NULL;
  Status = gBS->InstallMultipleProtocolInterfaces (
                  &Handle,
                  &gEfiWatchdogTimerArchProtocolGuid,
                  &mWatchdogTimer,
                  NULL
                  );
  if (EFI_ERROR (Status)) {
    goto UnregisterHandler;
  }
 
  // Register for an ExitBootServicesEvent
  Status = gBS->CreateEvent (
                  EVT_SIGNAL_EXIT_BOOT_SERVICES,
                  TPL_NOTIFY,
                  WatchdogExitBootServicesEvent,
                  NULL,
                  &mEfiExitBootServicesEvent
                  );
  ASSERT_EFI_ERROR (Status);
 
  return EFI_SUCCESS;
 
UnregisterHandler:
  // Unregister the handler
  mInterruptProtocol->RegisterInterruptSource (
                        mInterruptProtocol,
                        FixedPcdGet32 (PcdGenericWatchdogEl2IntrNum),
                        NULL
                        );
  return Status;
}