VirtualRealTimeClockLib.c

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#include <PiDxe.h>
#include <Library/BaseLib.h>
#include <Library/DebugLib.h>
#include <Library/IoLib.h>
#include <Library/RealTimeClockLib.h>
#include <Library/TimerLib.h>
#include <Library/TimeBaseLib.h>
#include <Library/UefiRuntimeLib.h>
 
STATIC CONST CHAR16  mEpochVariableName[]    = L"RtcEpochSeconds";
STATIC CONST CHAR16  mTimeZoneVariableName[] = L"RtcTimeZone";
STATIC CONST CHAR16  mDaylightVariableName[] = L"RtcDaylight";
 
EFI_STATUS
EFIAPI
LibGetTime (
  OUT EFI_TIME               *Time,
  OUT EFI_TIME_CAPABILITIES  *Capabilities
  )
{
  EFI_STATUS  Status;
  INT16       TimeZone;
  UINT8       Daylight;
  UINT64      Freq;
  UINT64      Counter;
  UINT64      Remainder;
  UINTN       EpochSeconds;
  UINTN       Size;
 
  if (Time == NULL) {
    return EFI_INVALID_PARAMETER;
  }
 
  // Get the counter frequency
  Freq = GetPerformanceCounterProperties (NULL, NULL);
  if (Freq == 0) {
    return EFI_DEVICE_ERROR;
  }
 
  // Get the epoch time from non-volatile storage
  Size         = sizeof (UINTN);
  EpochSeconds = 0;
  Status       = EfiGetVariable (
                   (CHAR16 *)mEpochVariableName,
                   &gEfiCallerIdGuid,
                   NULL,
                   &Size,
                   (VOID *)&EpochSeconds
                   );
  // Fall back to compilation-time epoch if not set
  if (EFI_ERROR (Status)) {
    ASSERT (Status != EFI_INVALID_PARAMETER);
    ASSERT (Status != EFI_BUFFER_TOO_SMALL);
    //
    // The following is intended to produce a compilation error on build
    // environments where BUILD_EPOCH can not be set from inline shell.
    // If you are attempting to use this library on such an environment, please
    // contact the edk2 mailing list, so we can try to add support for it.
    //
    EpochSeconds = BUILD_EPOCH;
    DEBUG ((
      DEBUG_INFO,
      "LibGetTime: %s non volatile variable was not found - Using compilation time epoch.\n",
      mEpochVariableName
      ));
 
    EfiSetVariable (
      (CHAR16 *)mEpochVariableName,
      &gEfiCallerIdGuid,
      EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
      sizeof (EpochSeconds),
      &EpochSeconds
      );
  }
 
  Counter       = GetPerformanceCounter ();
  EpochSeconds += DivU64x64Remainder (Counter, Freq, &Remainder);
 
  // Get the current time zone information from non-volatile storage
  Size   = sizeof (TimeZone);
  Status = EfiGetVariable (
             (CHAR16 *)mTimeZoneVariableName,
             &gEfiCallerIdGuid,
             NULL,
             &Size,
             (VOID *)&TimeZone
             );
 
  if (EFI_ERROR (Status)) {
    ASSERT (Status != EFI_INVALID_PARAMETER);
    ASSERT (Status != EFI_BUFFER_TOO_SMALL);
 
    if (Status != EFI_NOT_FOUND) {
      return Status;
    }
 
    // The time zone variable does not exist in non-volatile storage, so create it.
    Time->TimeZone = EFI_UNSPECIFIED_TIMEZONE;
    // Store it
    Status = EfiSetVariable (
               (CHAR16 *)mTimeZoneVariableName,
               &gEfiCallerIdGuid,
               EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
               Size,
               (VOID *)&(Time->TimeZone)
               );
    if (EFI_ERROR (Status)) {
      DEBUG ((
        DEBUG_ERROR,
        "LibGetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
        mTimeZoneVariableName,
        Status
        ));
      return Status;
    }
  } else {
    // Got the time zone
    Time->TimeZone = TimeZone;
 
    // Check TimeZone bounds: -1440 to 1440 or 2047
    if (  ((Time->TimeZone < -1440) || (Time->TimeZone > 1440))
       && (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE))
    {
      Time->TimeZone = EFI_UNSPECIFIED_TIMEZONE;
    }
 
    // Adjust for the correct time zone
    if (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE) {
      EpochSeconds += Time->TimeZone * SEC_PER_MIN;
    }
  }
 
  // Get the current daylight information from non-volatile storage
  Size   = sizeof (Daylight);
  Status = EfiGetVariable (
             (CHAR16 *)mDaylightVariableName,
             &gEfiCallerIdGuid,
             NULL,
             &Size,
             (VOID *)&Daylight
             );
 
  if (EFI_ERROR (Status)) {
    ASSERT (Status != EFI_INVALID_PARAMETER);
    ASSERT (Status != EFI_BUFFER_TOO_SMALL);
 
    if (Status != EFI_NOT_FOUND) {
      return Status;
    }
 
    // The daylight variable does not exist in non-volatile storage, so create it.
    Time->Daylight = 0;
    // Store it
    Status = EfiSetVariable (
               (CHAR16 *)mDaylightVariableName,
               &gEfiCallerIdGuid,
               EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
               Size,
               (VOID *)&(Time->Daylight)
               );
    if (EFI_ERROR (Status)) {
      DEBUG ((
        DEBUG_ERROR,
        "LibGetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
        mDaylightVariableName,
        Status
        ));
      return Status;
    }
  } else {
    // Got the daylight information
    Time->Daylight = Daylight;
 
    // Adjust for the correct period
    if ((Time->Daylight & EFI_TIME_IN_DAYLIGHT) == EFI_TIME_IN_DAYLIGHT) {
      // Convert to adjusted time, i.e. spring forwards one hour
      EpochSeconds += SEC_PER_HOUR;
    }
  }
 
  EpochToEfiTime (EpochSeconds, Time);
 
  // Because we use the performance counter, we can fill the Nanosecond attribute
  // provided that the remainder doesn't overflow 64-bit during multiplication.
  if (Remainder <= 18446744073U) {
    Time->Nanosecond = (UINT32)(MultU64x64 (Remainder, 1000000000U) / Freq);
  } else {
    DEBUG ((DEBUG_WARN, "LibGetTime: Nanosecond value not set (64-bit overflow).\n"));
  }
 
  if (Capabilities) {
    Capabilities->Accuracy   = 0;
    Capabilities->Resolution = 1;
    Capabilities->SetsToZero = FALSE;
  }
 
  return EFI_SUCCESS;
}
 
EFI_STATUS
EFIAPI
LibSetTime (
  IN EFI_TIME  *Time
  )
{
  EFI_STATUS  Status;
  UINT64      Freq;
  UINT64      Counter;
  UINT64      Remainder;
  UINTN       EpochSeconds;
 
  if (!IsTimeValid (Time)) {
    return EFI_INVALID_PARAMETER;
  }
 
  EpochSeconds = EfiTimeToEpoch (Time);
 
  // Adjust for the correct time zone, i.e. convert to UTC time zone
  if (  (Time->TimeZone != EFI_UNSPECIFIED_TIMEZONE)
     && (EpochSeconds > Time->TimeZone * SEC_PER_MIN))
  {
    EpochSeconds -= Time->TimeZone * SEC_PER_MIN;
  }
 
  // Adjust for the correct period
  if (  ((Time->Daylight & EFI_TIME_IN_DAYLIGHT) == EFI_TIME_IN_DAYLIGHT)
     && (EpochSeconds > SEC_PER_HOUR))
  {
    // Convert to un-adjusted time, i.e. fall back one hour
    EpochSeconds -= SEC_PER_HOUR;
  }
 
  // Use the performance counter to subtract the number of seconds
  // since platform reset. Without this, setting time from the shell
  // and immediately reading it back would result in a forward time
  // offset, of the duration during which the platform has been up.
  Freq = GetPerformanceCounterProperties (NULL, NULL);
  if (Freq != 0) {
    Counter = GetPerformanceCounter ();
    if (EpochSeconds > DivU64x64Remainder (Counter, Freq, &Remainder)) {
      EpochSeconds -= DivU64x64Remainder (Counter, Freq, &Remainder);
    }
  }
 
  // Save the current time zone information into non-volatile storage
  Status = EfiSetVariable (
             (CHAR16 *)mTimeZoneVariableName,
             &gEfiCallerIdGuid,
             EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
             sizeof (Time->TimeZone),
             (VOID *)&(Time->TimeZone)
             );
  if (EFI_ERROR (Status)) {
    DEBUG ((
      DEBUG_ERROR,
      "LibSetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
      mTimeZoneVariableName,
      Status
      ));
    return Status;
  }
 
  // Save the current daylight information into non-volatile storage
  Status = EfiSetVariable (
             (CHAR16 *)mDaylightVariableName,
             &gEfiCallerIdGuid,
             EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
             sizeof (Time->Daylight),
             (VOID *)&(Time->Daylight)
             );
  if (EFI_ERROR (Status)) {
    DEBUG ((
      DEBUG_ERROR,
      "LibSetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
      mDaylightVariableName,
      Status
      ));
    return Status;
  }
 
  Status = EfiSetVariable (
             (CHAR16 *)mEpochVariableName,
             &gEfiCallerIdGuid,
             EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
             sizeof (EpochSeconds),
             &EpochSeconds
             );
  if (EFI_ERROR (Status)) {
    DEBUG ((
      DEBUG_ERROR,
      "LibSetTime: Failed to save %s variable to non-volatile storage, Status = %r\n",
      mEpochVariableName,
      Status
      ));
    return Status;
  }
 
  return EFI_SUCCESS;
}
 
EFI_STATUS
EFIAPI
LibGetWakeupTime (
  OUT BOOLEAN   *Enabled,
  OUT BOOLEAN   *Pending,
  OUT EFI_TIME  *Time
  )
{
  return EFI_UNSUPPORTED;
}
 
EFI_STATUS
EFIAPI
LibSetWakeupTime (
  IN  BOOLEAN   Enabled,
  OUT EFI_TIME  *Time
  )
{
  return EFI_UNSUPPORTED;
}
 
EFI_STATUS
EFIAPI
LibRtcInitialize (
  IN EFI_HANDLE        ImageHandle,
  IN EFI_SYSTEM_TABLE  *SystemTable
  )
{
  return EFI_SUCCESS;
}