[mirror_edk2.git] / PcAtChipsetPkg / PcatRealTimeClockRuntimeDxe / PcRtc.c

/** @file\r
  RTC Architectural Protocol GUID as defined in DxeCis 0.96.\r
\r
Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>\r
Copyright (c) 2017, AMD Inc. All rights reserved.<BR>\r
Copyright (c) 2018 - 2020, ARM Limited. All rights reserved.<BR>\r
\r
SPDX-License-Identifier: BSD-2-Clause-Patent\r
\r
**/\r
\r
#include "PcRtc.h"\r
\r
extern UINTN  mRtcIndexRegister;\r
extern UINTN  mRtcTargetRegister;\r
\r
//\r
// Days of month.\r
//\r
UINTN  mDayOfMonth[] = { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };\r
\r
//\r
// The name of NV variable to store the timezone and daylight saving information.\r
//\r
CHAR16  mTimeZoneVariableName[] = L"RTC";\r
\r
/**\r
  Compare the Hour, Minute and Second of the From time and the To time.\r
\r
  Only compare H/M/S in EFI_TIME and ignore other fields here.\r
\r
  @param From   the first time\r
  @param To     the second time\r
\r
  @return  >0   The H/M/S of the From time is later than those of To time\r
  @return  ==0  The H/M/S of the From time is same as those of To time\r
  @return  <0   The H/M/S of the From time is earlier than those of To time\r
**/\r
INTN\r
CompareHMS (\r
  IN EFI_TIME  *From,\r
  IN EFI_TIME  *To\r
  );\r
\r
/**\r
  To check if second date is later than first date within 24 hours.\r
\r
  @param  From   the first date\r
  @param  To     the second date\r
\r
  @retval TRUE   From is previous to To within 24 hours.\r
  @retval FALSE  From is later, or it is previous to To more than 24 hours.\r
**/\r
BOOLEAN\r
IsWithinOneDay (\r
  IN EFI_TIME  *From,\r
  IN EFI_TIME  *To\r
  );\r
\r
/**\r
  Read RTC content through its registers using IO access.\r
\r
  @param  Address   Address offset of RTC. It is recommended to use\r
                    macros such as RTC_ADDRESS_SECONDS.\r
\r
  @return The data of UINT8 type read from RTC.\r
**/\r
STATIC\r
UINT8\r
IoRtcRead (\r
  IN  UINTN  Address\r
  )\r
{\r
  IoWrite8 (\r
    PcdGet8 (PcdRtcIndexRegister),\r
    (UINT8)(Address | (UINT8)(IoRead8 (PcdGet8 (PcdRtcIndexRegister)) & 0x80))\r
    );\r
  return IoRead8 (PcdGet8 (PcdRtcTargetRegister));\r
}\r
\r
/**\r
  Write RTC through its registers  using IO access.\r
\r
  @param  Address   Address offset of RTC. It is recommended to use\r
                    macros such as RTC_ADDRESS_SECONDS.\r
  @param  Data      The content you want to write into RTC.\r
\r
**/\r
STATIC\r
VOID\r
IoRtcWrite (\r
  IN  UINTN  Address,\r
  IN  UINT8  Data\r
  )\r
{\r
  IoWrite8 (\r
    PcdGet8 (PcdRtcIndexRegister),\r
    (UINT8)(Address | (UINT8)(IoRead8 (PcdGet8 (PcdRtcIndexRegister)) & 0x80))\r
    );\r
  IoWrite8 (PcdGet8 (PcdRtcTargetRegister), Data);\r
}\r
\r
/**\r
  Read RTC content through its registers using MMIO access.\r
\r
  @param  Address   Address offset of RTC. It is recommended to use\r
                    macros such as RTC_ADDRESS_SECONDS.\r
\r
  @return The data of UINT8 type read from RTC.\r
**/\r
STATIC\r
UINT8\r
MmioRtcRead (\r
  IN  UINTN  Address\r
  )\r
{\r
  MmioWrite8 (\r
    mRtcIndexRegister,\r
    (UINT8)(Address | (UINT8)(MmioRead8 (mRtcIndexRegister) & 0x80))\r
    );\r
  return MmioRead8 (mRtcTargetRegister);\r
}\r
\r
/**\r
  Write RTC through its registers using MMIO access.\r
\r
  @param  Address   Address offset of RTC. It is recommended to use\r
                    macros such as RTC_ADDRESS_SECONDS.\r
  @param  Data      The content you want to write into RTC.\r
\r
**/\r
STATIC\r
VOID\r
MmioRtcWrite (\r
  IN  UINTN  Address,\r
  IN  UINT8  Data\r
  )\r
{\r
  MmioWrite8 (\r
    mRtcIndexRegister,\r
    (UINT8)(Address | (UINT8)(MmioRead8 (mRtcIndexRegister) & 0x80))\r
    );\r
  MmioWrite8 (mRtcTargetRegister, Data);\r
}\r
\r
/**\r
  Read RTC content through its registers.\r
\r
  @param  Address   Address offset of RTC. It is recommended to use\r
                    macros such as RTC_ADDRESS_SECONDS.\r
\r
  @return The data of UINT8 type read from RTC.\r
**/\r
STATIC\r
UINT8\r
RtcRead (\r
  IN  UINTN  Address\r
  )\r
{\r
  if (FeaturePcdGet (PcdRtcUseMmio)) {\r
    return MmioRtcRead (Address);\r
  }\r
\r
  return IoRtcRead (Address);\r
}\r
\r
/**\r
  Write RTC through its registers.\r
\r
  @param  Address   Address offset of RTC. It is recommended to use\r
                    macros such as RTC_ADDRESS_SECONDS.\r
  @param  Data      The content you want to write into RTC.\r
\r
**/\r
STATIC\r
VOID\r
RtcWrite (\r
  IN  UINTN  Address,\r
  IN  UINT8  Data\r
  )\r
{\r
  if (FeaturePcdGet (PcdRtcUseMmio)) {\r
    MmioRtcWrite (Address, Data);\r
  } else {\r
    IoRtcWrite (Address, Data);\r
  }\r
}\r
\r
/**\r
  Initialize RTC.\r
\r
  @param  Global            For global use inside this module.\r
\r
  @retval EFI_DEVICE_ERROR  Initialization failed due to device error.\r
  @retval EFI_SUCCESS       Initialization successful.\r
\r
**/\r
EFI_STATUS\r
PcRtcInit (\r
  IN PC_RTC_MODULE_GLOBALS  *Global\r
  )\r
{\r
  EFI_STATUS      Status;\r
  RTC_REGISTER_A  RegisterA;\r
  RTC_REGISTER_B  RegisterB;\r
  RTC_REGISTER_D  RegisterD;\r
  EFI_TIME        Time;\r
  UINTN           DataSize;\r
  UINT32          TimerVar;\r
  BOOLEAN         Enabled;\r
  BOOLEAN         Pending;\r
\r
  //\r
  // Acquire RTC Lock to make access to RTC atomic\r
  //\r
  if (!EfiAtRuntime ()) {\r
    EfiAcquireLock (&Global->RtcLock);\r
  }\r
\r
  //\r
  // Initialize RTC Register\r
  //\r
  // Make sure Division Chain is properly configured,\r
  // or RTC clock won't "tick" -- time won't increment\r
  //\r
  RegisterA.Data = FixedPcdGet8 (PcdInitialValueRtcRegisterA);\r
  RtcWrite (RTC_ADDRESS_REGISTER_A, RegisterA.Data);\r
\r
  //\r
  // Read Register B\r
  //\r
  RegisterB.Data = RtcRead (RTC_ADDRESS_REGISTER_B);\r
\r
  //\r
  // Clear RTC flag register\r
  //\r
  RtcRead (RTC_ADDRESS_REGISTER_C);\r
\r
  //\r
  // Clear RTC register D\r
  //\r
  RegisterD.Data = FixedPcdGet8 (PcdInitialValueRtcRegisterD);\r
  RtcWrite (RTC_ADDRESS_REGISTER_D, RegisterD.Data);\r
\r
  //\r
  // Wait for up to 0.1 seconds for the RTC to be updated\r
  //\r
  Status = RtcWaitToUpdate (PcdGet32 (PcdRealTimeClockUpdateTimeout));\r
  if (EFI_ERROR (Status)) {\r
    //\r
    // Set the variable with default value if the RTC is functioning incorrectly.\r
    //\r
    Global->SavedTimeZone = EFI_UNSPECIFIED_TIMEZONE;\r
    Global->Daylight      = 0;\r
    if (!EfiAtRuntime ()) {\r
      EfiReleaseLock (&Global->RtcLock);\r
    }\r
\r
    return EFI_DEVICE_ERROR;\r
  }\r
\r
  //\r
  // Get the Time/Date/Daylight Savings values.\r
  //\r
  Time.Second = RtcRead (RTC_ADDRESS_SECONDS);\r
  Time.Minute = RtcRead (RTC_ADDRESS_MINUTES);\r
  Time.Hour   = RtcRead (RTC_ADDRESS_HOURS);\r
  Time.Day    = RtcRead (RTC_ADDRESS_DAY_OF_THE_MONTH);\r
  Time.Month  = RtcRead (RTC_ADDRESS_MONTH);\r
  Time.Year   = RtcRead (RTC_ADDRESS_YEAR);\r
\r
  //\r
  // Set RTC configuration after get original time\r
  // The value of bit AIE should be reserved.\r
  //\r
  RegisterB.Data = FixedPcdGet8 (PcdInitialValueRtcRegisterB) | (RegisterB.Data & BIT5);\r
  RtcWrite (RTC_ADDRESS_REGISTER_B, RegisterB.Data);\r
\r
  //\r
  // Release RTC Lock.\r
  //\r
  if (!EfiAtRuntime ()) {\r
    EfiReleaseLock (&Global->RtcLock);\r
  }\r
\r
  //\r
  // Get the data of Daylight saving and time zone, if they have been\r
  // stored in NV variable during previous boot.\r
  //\r
  DataSize = sizeof (UINT32);\r
  Status   = EfiGetVariable (\r
               mTimeZoneVariableName,\r
               &gEfiCallerIdGuid,\r
               NULL,\r
               &DataSize,\r
               &TimerVar\r
               );\r
  if (!EFI_ERROR (Status)) {\r
    Time.TimeZone = (INT16)TimerVar;\r
    Time.Daylight = (UINT8)(TimerVar >> 16);\r
  } else {\r
    Time.TimeZone = EFI_UNSPECIFIED_TIMEZONE;\r
    Time.Daylight = 0;\r
  }\r
\r
  //\r
  // Validate time fields\r
  //\r
  Status = ConvertRtcTimeToEfiTime (&Time, RegisterB);\r
  if (!EFI_ERROR (Status)) {\r
    Status = RtcTimeFieldsValid (&Time);\r
  }\r
\r
  if (EFI_ERROR (Status)) {\r
    //\r
    // Report Status Code to indicate that the RTC has bad date and time\r
    //\r
    REPORT_STATUS_CODE (\r
      EFI_ERROR_CODE | EFI_ERROR_MINOR,\r
      (EFI_SOFTWARE_DXE_RT_DRIVER | EFI_SW_EC_BAD_DATE_TIME)\r
      );\r
    Time.Second     = RTC_INIT_SECOND;\r
    Time.Minute     = RTC_INIT_MINUTE;\r
    Time.Hour       = RTC_INIT_HOUR;\r
    Time.Day        = RTC_INIT_DAY;\r
    Time.Month      = RTC_INIT_MONTH;\r
    Time.Year       = PcdGet16 (PcdMinimalValidYear);\r
    Time.Nanosecond = 0;\r
    Time.TimeZone   = EFI_UNSPECIFIED_TIMEZONE;\r
    Time.Daylight   = 0;\r
  }\r
\r
  //\r
  // Reset time value according to new RTC configuration\r
  //\r
  Status = PcRtcSetTime (&Time, Global);\r
  if (EFI_ERROR (Status)) {\r
    return EFI_DEVICE_ERROR;\r
  }\r
\r
  //\r
  // Reset wakeup time value to valid state when wakeup alarm is disabled and wakeup time is invalid.\r
  // Global variable has already had valid SavedTimeZone and Daylight,\r
  // so we can use them to get and set wakeup time.\r
  //\r
  Status = PcRtcGetWakeupTime (&Enabled, &Pending, &Time, Global);\r
  if ((Enabled) || (!EFI_ERROR (Status))) {\r
    return EFI_SUCCESS;\r
  }\r
\r
  //\r
  // When wakeup time is disabled and invalid, reset wakeup time register to valid state\r
  // but keep wakeup alarm disabled.\r
  //\r
  Time.Second     = RTC_INIT_SECOND;\r
  Time.Minute     = RTC_INIT_MINUTE;\r
  Time.Hour       = RTC_INIT_HOUR;\r
  Time.Day        = RTC_INIT_DAY;\r
  Time.Month      = RTC_INIT_MONTH;\r
  Time.Year       = PcdGet16 (PcdMinimalValidYear);\r
  Time.Nanosecond = 0;\r
  Time.TimeZone   = Global->SavedTimeZone;\r
  Time.Daylight   = Global->Daylight;\r
\r
  //\r
  // Acquire RTC Lock to make access to RTC atomic\r
  //\r
  if (!EfiAtRuntime ()) {\r
    EfiAcquireLock (&Global->RtcLock);\r
  }\r
\r
  //\r
  // Wait for up to 0.1 seconds for the RTC to be updated\r
  //\r
  Status = RtcWaitToUpdate (PcdGet32 (PcdRealTimeClockUpdateTimeout));\r
  if (EFI_ERROR (Status)) {\r
    if (!EfiAtRuntime ()) {\r
      EfiReleaseLock (&Global->RtcLock);\r
    }\r
\r
    return EFI_DEVICE_ERROR;\r
  }\r
\r
  ConvertEfiTimeToRtcTime (&Time, RegisterB);\r
\r
  //\r
  // Set the Y/M/D info to variable as it has no corresponding hw registers.\r
  //\r
  Status =  EfiSetVariable (\r
              L"RTCALARM",\r
              &gEfiCallerIdGuid,\r
              EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_NON_VOLATILE,\r
              sizeof (Time),\r
              &Time\r
              );\r
  if (EFI_ERROR (Status)) {\r
    if (!EfiAtRuntime ()) {\r
      EfiReleaseLock (&Global->RtcLock);\r
    }\r
\r
    return EFI_DEVICE_ERROR;\r
  }\r
\r
  //\r
  // Inhibit updates of the RTC\r
  //\r
  RegisterB.Bits.Set = 1;\r
  RtcWrite (RTC_ADDRESS_REGISTER_B, RegisterB.Data);\r
\r
  //\r
  // Set RTC alarm time registers\r
  //\r
  RtcWrite (RTC_ADDRESS_SECONDS_ALARM, Time.Second);\r
  RtcWrite (RTC_ADDRESS_MINUTES_ALARM, Time.Minute);\r
  RtcWrite (RTC_ADDRESS_HOURS_ALARM, Time.Hour);\r
\r
  //\r
  // Allow updates of the RTC registers\r
  //\r
  RegisterB.Bits.Set = 0;\r
  RtcWrite (RTC_ADDRESS_REGISTER_B, RegisterB.Data);\r
\r
  //\r
  // Release RTC Lock.\r
  //\r
  if (!EfiAtRuntime ()) {\r
    EfiReleaseLock (&Global->RtcLock);\r
  }\r
\r
  return EFI_SUCCESS;\r
}\r
\r
/**\r
  Returns the current time and date information, and the time-keeping capabilities\r
  of the hardware platform.\r
\r
  @param  Time          A pointer to storage to receive a snapshot of the current time.\r
  @param  Capabilities  An optional pointer to a buffer to receive the real time clock\r
                        device's capabilities.\r
  @param  Global        For global use inside this module.\r
\r
  @retval EFI_SUCCESS            The operation completed successfully.\r
  @retval EFI_INVALID_PARAMETER  Time is NULL.\r
  @retval EFI_DEVICE_ERROR       The time could not be retrieved due to hardware error.\r
\r
**/\r
EFI_STATUS\r
PcRtcGetTime (\r
  OUT  EFI_TIME               *Time,\r
  OUT  EFI_TIME_CAPABILITIES  *Capabilities   OPTIONAL,\r
  IN   PC_RTC_MODULE_GLOBALS  *Global\r
  )\r
{\r
  EFI_STATUS      Status;\r
  RTC_REGISTER_B  RegisterB;\r
\r
  //\r
  // Check parameters for null pointer\r
  //\r
  if (Time == NULL) {\r
    return EFI_INVALID_PARAMETER;\r
  }\r
\r
  //\r
  // Acquire RTC Lock to make access to RTC atomic\r
  //\r
  if (!EfiAtRuntime ()) {\r
    EfiAcquireLock (&Global->RtcLock);\r
  }\r
\r
  //\r
  // Wait for up to 0.1 seconds for the RTC to be updated\r
  //\r
  Status = RtcWaitToUpdate (PcdGet32 (PcdRealTimeClockUpdateTimeout));\r
  if (EFI_ERROR (Status)) {\r
    if (!EfiAtRuntime ()) {\r
      EfiReleaseLock (&Global->RtcLock);\r
    }\r
\r
    return Status;\r
  }\r
\r
  //\r
  // Read Register B\r
  //\r
  RegisterB.Data = RtcRead (RTC_ADDRESS_REGISTER_B);\r
\r
  //\r
  // Get the Time/Date/Daylight Savings values.\r
  //\r
  Time->Second = RtcRead (RTC_ADDRESS_SECONDS);\r
  Time->Minute = RtcRead (RTC_ADDRESS_MINUTES);\r
  Time->Hour   = RtcRead (RTC_ADDRESS_HOURS);\r
  Time->Day    = RtcRead (RTC_ADDRESS_DAY_OF_THE_MONTH);\r
  Time->Month  = RtcRead (RTC_ADDRESS_MONTH);\r
  Time->Year   = RtcRead (RTC_ADDRESS_YEAR);\r
\r
  //\r
  // Release RTC Lock.\r
  //\r
  if (!EfiAtRuntime ()) {\r
    EfiReleaseLock (&Global->RtcLock);\r
  }\r
\r
  //\r
  // Get the variable that contains the TimeZone and Daylight fields\r
  //\r
  Time->TimeZone = Global->SavedTimeZone;\r
  Time->Daylight = Global->Daylight;\r
\r
  //\r
  // Make sure all field values are in correct range\r
  //\r
  Status = ConvertRtcTimeToEfiTime (Time, RegisterB);\r
  if (!EFI_ERROR (Status)) {\r
    Status = RtcTimeFieldsValid (Time);\r
  }\r
\r
  if (EFI_ERROR (Status)) {\r
    return EFI_DEVICE_ERROR;\r
  }\r
\r
  //\r
  //  Fill in Capabilities if it was passed in\r
  //\r
  if (Capabilities != NULL) {\r
    Capabilities->Resolution = 1;\r
    //\r
    // 1 hertz\r
    //\r
    Capabilities->Accuracy = 50000000;\r
    //\r
    // 50 ppm\r
    //\r
    Capabilities->SetsToZero = FALSE;\r
  }\r
\r
  return EFI_SUCCESS;\r
}\r
\r
/**\r
  Sets the current local time and date information.\r
\r
  @param  Time                  A pointer to the current time.\r
  @param  Global                For global use inside this module.\r
\r
  @retval EFI_SUCCESS           The operation completed successfully.\r
  @retval EFI_INVALID_PARAMETER A time field is out of range.\r
  @retval EFI_DEVICE_ERROR      The time could not be set due due to hardware error.\r
\r
**/\r
EFI_STATUS\r
PcRtcSetTime (\r
  IN EFI_TIME               *Time,\r
  IN PC_RTC_MODULE_GLOBALS  *Global\r
  )\r
{\r
  EFI_STATUS      Status;\r
  EFI_TIME        RtcTime;\r
  RTC_REGISTER_B  RegisterB;\r
  UINT32          TimerVar;\r
\r
  if (Time == NULL) {\r
    return EFI_INVALID_PARAMETER;\r
  }\r
\r
  //\r
  // Make sure that the time fields are valid\r
  //\r
  Status = RtcTimeFieldsValid (Time);\r
  if (EFI_ERROR (Status)) {\r
    return Status;\r
  }\r
\r
  CopyMem (&RtcTime, Time, sizeof (EFI_TIME));\r
\r
  //\r
  // Acquire RTC Lock to make access to RTC atomic\r
  //\r
  if (!EfiAtRuntime ()) {\r
    EfiAcquireLock (&Global->RtcLock);\r
  }\r
\r
  //\r
  // Wait for up to 0.1 seconds for the RTC to be updated\r
  //\r
  Status = RtcWaitToUpdate (PcdGet32 (PcdRealTimeClockUpdateTimeout));\r
  if (EFI_ERROR (Status)) {\r
    if (!EfiAtRuntime ()) {\r
      EfiReleaseLock (&Global->RtcLock);\r
    }\r
\r
    return Status;\r
  }\r
\r
  //\r
  // Write timezone and daylight to RTC variable\r
  //\r
  if ((Time->TimeZone == EFI_UNSPECIFIED_TIMEZONE) && (Time->Daylight == 0)) {\r
    Status = EfiSetVariable (\r
               mTimeZoneVariableName,\r
               &gEfiCallerIdGuid,\r
               0,\r
               0,\r
               NULL\r
               );\r
    if (Status == EFI_NOT_FOUND) {\r
      Status = EFI_SUCCESS;\r
    }\r
  } else {\r
    TimerVar = Time->Daylight;\r
    TimerVar = (UINT32)((TimerVar << 16) | (UINT16)(Time->TimeZone));\r
    Status   = EfiSetVariable (\r
                 mTimeZoneVariableName,\r
                 &gEfiCallerIdGuid,\r
                 EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_NON_VOLATILE,\r
                 sizeof (TimerVar),\r
                 &TimerVar\r
                 );\r
  }\r
\r
  if (EFI_ERROR (Status)) {\r
    if (!EfiAtRuntime ()) {\r
      EfiReleaseLock (&Global->RtcLock);\r
    }\r
\r
    return EFI_DEVICE_ERROR;\r
  }\r
\r
  //\r
  // Read Register B, and inhibit updates of the RTC\r
  //\r
  RegisterB.Data     = RtcRead (RTC_ADDRESS_REGISTER_B);\r
  RegisterB.Bits.Set = 1;\r
  RtcWrite (RTC_ADDRESS_REGISTER_B, RegisterB.Data);\r
\r
  //\r
  // Store the century value to RTC before converting to BCD format.\r
  //\r
  if (Global->CenturyRtcAddress != 0) {\r
    RtcWrite (Global->CenturyRtcAddress, DecimalToBcd8 ((UINT8)(RtcTime.Year / 100)));\r
  }\r
\r
  ConvertEfiTimeToRtcTime (&RtcTime, RegisterB);\r
\r
  RtcWrite (RTC_ADDRESS_SECONDS, RtcTime.Second);\r
  RtcWrite (RTC_ADDRESS_MINUTES, RtcTime.Minute);\r
  RtcWrite (RTC_ADDRESS_HOURS, RtcTime.Hour);\r
  RtcWrite (RTC_ADDRESS_DAY_OF_THE_MONTH, RtcTime.Day);\r
  RtcWrite (RTC_ADDRESS_MONTH, RtcTime.Month);\r
  RtcWrite (RTC_ADDRESS_YEAR, (UINT8)RtcTime.Year);\r
\r
  //\r
  // Allow updates of the RTC registers\r
  //\r
  RegisterB.Bits.Set = 0;\r
  RtcWrite (RTC_ADDRESS_REGISTER_B, RegisterB.Data);\r
\r
  //\r
  // Release RTC Lock.\r
  //\r
  if (!EfiAtRuntime ()) {\r
    EfiReleaseLock (&Global->RtcLock);\r
  }\r
\r
  //\r
  // Set the variable that contains the TimeZone and Daylight fields\r
  //\r
  Global->SavedTimeZone = Time->TimeZone;\r
  Global->Daylight      = Time->Daylight;\r
\r
  return EFI_SUCCESS;\r
}\r
\r
/**\r
  Returns the current wakeup alarm clock setting.\r
\r
  @param  Enabled  Indicates if the alarm is currently enabled or disabled.\r
  @param  Pending  Indicates if the alarm signal is pending and requires acknowledgment.\r
  @param  Time     The current alarm setting.\r
  @param  Global   For global use inside this module.\r
\r
  @retval EFI_SUCCESS           The alarm settings were returned.\r
  @retval EFI_INVALID_PARAMETER Enabled is NULL.\r
  @retval EFI_INVALID_PARAMETER Pending is NULL.\r
  @retval EFI_INVALID_PARAMETER Time is NULL.\r
  @retval EFI_DEVICE_ERROR      The wakeup time could not be retrieved due to a hardware error.\r
  @retval EFI_UNSUPPORTED       A wakeup timer is not supported on this platform.\r
\r
**/\r
EFI_STATUS\r
PcRtcGetWakeupTime (\r
  OUT BOOLEAN                *Enabled,\r
  OUT BOOLEAN                *Pending,\r
  OUT EFI_TIME               *Time,\r
  IN  PC_RTC_MODULE_GLOBALS  *Global\r
  )\r
{\r
  EFI_STATUS      Status;\r
  RTC_REGISTER_B  RegisterB;\r
  RTC_REGISTER_C  RegisterC;\r
  EFI_TIME        RtcTime;\r
  UINTN           DataSize;\r
\r
  //\r
  // Check parameters for null pointers\r
  //\r
  if ((Enabled == NULL) || (Pending == NULL) || (Time == NULL)) {\r
    return EFI_INVALID_PARAMETER;\r
  }\r
\r
  //\r
  // Acquire RTC Lock to make access to RTC atomic\r
  //\r
  if (!EfiAtRuntime ()) {\r
    EfiAcquireLock (&Global->RtcLock);\r
  }\r
\r
  //\r
  // Wait for up to 0.1 seconds for the RTC to be updated\r
  //\r
  Status = RtcWaitToUpdate (PcdGet32 (PcdRealTimeClockUpdateTimeout));\r
  if (EFI_ERROR (Status)) {\r
    if (!EfiAtRuntime ()) {\r
      EfiReleaseLock (&Global->RtcLock);\r
    }\r
\r
    return EFI_DEVICE_ERROR;\r
  }\r
\r
  //\r
  // Read Register B and Register C\r
  //\r
  RegisterB.Data = RtcRead (RTC_ADDRESS_REGISTER_B);\r
  RegisterC.Data = RtcRead (RTC_ADDRESS_REGISTER_C);\r
\r
  //\r
  // Get the Time/Date/Daylight Savings values.\r
  //\r
  *Enabled = RegisterB.Bits.Aie;\r
  *Pending = RegisterC.Bits.Af;\r
\r
  Time->Second   = RtcRead (RTC_ADDRESS_SECONDS_ALARM);\r
  Time->Minute   = RtcRead (RTC_ADDRESS_MINUTES_ALARM);\r
  Time->Hour     = RtcRead (RTC_ADDRESS_HOURS_ALARM);\r
  Time->Day      = RtcRead (RTC_ADDRESS_DAY_OF_THE_MONTH);\r
  Time->Month    = RtcRead (RTC_ADDRESS_MONTH);\r
  Time->Year     = RtcRead (RTC_ADDRESS_YEAR);\r
  Time->TimeZone = Global->SavedTimeZone;\r
  Time->Daylight = Global->Daylight;\r
\r
  //\r
  // Get the alarm info from variable\r
  //\r
  DataSize = sizeof (EFI_TIME);\r
  Status   = EfiGetVariable (\r
               L"RTCALARM",\r
               &gEfiCallerIdGuid,\r
               NULL,\r
               &DataSize,\r
               &RtcTime\r
               );\r
  if (!EFI_ERROR (Status)) {\r
    //\r
    // The alarm variable exists. In this case, we read variable to get info.\r
    //\r
    Time->Day   = RtcTime.Day;\r
    Time->Month = RtcTime.Month;\r
    Time->Year  = RtcTime.Year;\r
  }\r
\r
  //\r
  // Release RTC Lock.\r
  //\r
  if (!EfiAtRuntime ()) {\r
    EfiReleaseLock (&Global->RtcLock);\r
  }\r
\r
  //\r
  // Make sure all field values are in correct range\r
  //\r
  Status = ConvertRtcTimeToEfiTime (Time, RegisterB);\r
  if (!EFI_ERROR (Status)) {\r
    Status = RtcTimeFieldsValid (Time);\r
  }\r
\r
  if (EFI_ERROR (Status)) {\r
    return EFI_DEVICE_ERROR;\r
  }\r
\r
  return EFI_SUCCESS;\r
}\r
\r
/**\r
  Sets the system wakeup alarm clock time.\r
\r
  @param  Enabled  Enable or disable the wakeup alarm.\r
  @param  Time     If Enable is TRUE, the time to set the wakeup alarm for.\r
                   If Enable is FALSE, then this parameter is optional, and may be NULL.\r
  @param  Global   For global use inside this module.\r
\r
  @retval EFI_SUCCESS           If Enable is TRUE, then the wakeup alarm was enabled.\r
                                If Enable is FALSE, then the wakeup alarm was disabled.\r
  @retval EFI_INVALID_PARAMETER A time field is out of range.\r
  @retval EFI_DEVICE_ERROR      The wakeup time could not be set due to a hardware error.\r
  @retval EFI_UNSUPPORTED       A wakeup timer is not supported on this platform.\r
\r
**/\r
EFI_STATUS\r
PcRtcSetWakeupTime (\r
  IN BOOLEAN                Enable,\r
  IN EFI_TIME               *Time    OPTIONAL,\r
  IN PC_RTC_MODULE_GLOBALS  *Global\r
  )\r
{\r
  EFI_STATUS             Status;\r
  EFI_TIME               RtcTime;\r
  RTC_REGISTER_B         RegisterB;\r
  EFI_TIME_CAPABILITIES  Capabilities;\r
\r
  ZeroMem (&RtcTime, sizeof (RtcTime));\r
\r
  if (Enable) {\r
    if (Time == NULL) {\r
      return EFI_INVALID_PARAMETER;\r
    }\r
\r
    //\r
    // Make sure that the time fields are valid\r
    //\r
    Status = RtcTimeFieldsValid (Time);\r
    if (EFI_ERROR (Status)) {\r
      return EFI_INVALID_PARAMETER;\r
    }\r
\r
    //\r
    // Just support set alarm time within 24 hours\r
    //\r
    PcRtcGetTime (&RtcTime, &Capabilities, Global);\r
    Status = RtcTimeFieldsValid (&RtcTime);\r
    if (EFI_ERROR (Status)) {\r
      return EFI_DEVICE_ERROR;\r
    }\r
\r
    if (!IsWithinOneDay (&RtcTime, Time)) {\r
      return EFI_UNSUPPORTED;\r
    }\r
\r
    //\r
    // Make a local copy of the time and date\r
    //\r
    CopyMem (&RtcTime, Time, sizeof (EFI_TIME));\r
  }\r
\r
  //\r
  // Acquire RTC Lock to make access to RTC atomic\r
  //\r
  if (!EfiAtRuntime ()) {\r
    EfiAcquireLock (&Global->RtcLock);\r
  }\r
\r
  //\r
  // Wait for up to 0.1 seconds for the RTC to be updated\r
  //\r
  Status = RtcWaitToUpdate (PcdGet32 (PcdRealTimeClockUpdateTimeout));\r
  if (EFI_ERROR (Status)) {\r
    if (!EfiAtRuntime ()) {\r
      EfiReleaseLock (&Global->RtcLock);\r
    }\r
\r
    return EFI_DEVICE_ERROR;\r
  }\r
\r
  //\r
  // Read Register B\r
  //\r
  RegisterB.Data = RtcRead (RTC_ADDRESS_REGISTER_B);\r
\r
  if (Enable) {\r
    ConvertEfiTimeToRtcTime (&RtcTime, RegisterB);\r
  } else {\r
    //\r
    // if the alarm is disable, record the current setting.\r
    //\r
    RtcTime.Second   = RtcRead (RTC_ADDRESS_SECONDS_ALARM);\r
    RtcTime.Minute   = RtcRead (RTC_ADDRESS_MINUTES_ALARM);\r
    RtcTime.Hour     = RtcRead (RTC_ADDRESS_HOURS_ALARM);\r
    RtcTime.Day      = RtcRead (RTC_ADDRESS_DAY_OF_THE_MONTH);\r
    RtcTime.Month    = RtcRead (RTC_ADDRESS_MONTH);\r
    RtcTime.Year     = RtcRead (RTC_ADDRESS_YEAR);\r
    RtcTime.TimeZone = Global->SavedTimeZone;\r
    RtcTime.Daylight = Global->Daylight;\r
  }\r
\r
  //\r
  // Set the Y/M/D info to variable as it has no corresponding hw registers.\r
  //\r
  Status =  EfiSetVariable (\r
              L"RTCALARM",\r
              &gEfiCallerIdGuid,\r
              EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_NON_VOLATILE,\r
              sizeof (RtcTime),\r
              &RtcTime\r
              );\r
  if (EFI_ERROR (Status)) {\r
    if (!EfiAtRuntime ()) {\r
      EfiReleaseLock (&Global->RtcLock);\r
    }\r
\r
    return EFI_DEVICE_ERROR;\r
  }\r
\r
  //\r
  // Inhibit updates of the RTC\r
  //\r
  RegisterB.Bits.Set = 1;\r
  RtcWrite (RTC_ADDRESS_REGISTER_B, RegisterB.Data);\r
\r
  if (Enable) {\r
    //\r
    // Set RTC alarm time\r
    //\r
    RtcWrite (RTC_ADDRESS_SECONDS_ALARM, RtcTime.Second);\r
    RtcWrite (RTC_ADDRESS_MINUTES_ALARM, RtcTime.Minute);\r
    RtcWrite (RTC_ADDRESS_HOURS_ALARM, RtcTime.Hour);\r
\r
    RegisterB.Bits.Aie = 1;\r
  } else {\r
    RegisterB.Bits.Aie = 0;\r
  }\r
\r
  //\r
  // Allow updates of the RTC registers\r
  //\r
  RegisterB.Bits.Set = 0;\r
  RtcWrite (RTC_ADDRESS_REGISTER_B, RegisterB.Data);\r
\r
  //\r
  // Release RTC Lock.\r
  //\r
  if (!EfiAtRuntime ()) {\r
    EfiReleaseLock (&Global->RtcLock);\r
  }\r
\r
  return EFI_SUCCESS;\r
}\r
\r
/**\r
  Checks an 8-bit BCD value, and converts to an 8-bit value if valid.\r
\r
  This function checks the 8-bit BCD value specified by Value.\r
  If valid, the function converts it to an 8-bit value and returns it.\r
  Otherwise, return 0xff.\r
\r
  @param   Value The 8-bit BCD value to check and convert\r
\r
  @return  The 8-bit value converted. Or 0xff if Value is invalid.\r
\r
**/\r
UINT8\r
CheckAndConvertBcd8ToDecimal8 (\r
  IN  UINT8  Value\r
  )\r
{\r
  if ((Value < 0xa0) && ((Value & 0xf) < 0xa)) {\r
    return BcdToDecimal8 (Value);\r
  }\r
\r
  return 0xff;\r
}\r
\r
/**\r
  Converts time read from RTC to EFI_TIME format defined by UEFI spec.\r
\r
  This function converts raw time data read from RTC to the EFI_TIME format\r
  defined by UEFI spec.\r
  If data mode of RTC is BCD, then converts it to decimal,\r
  If RTC is in 12-hour format, then converts it to 24-hour format.\r
\r
  @param   Time       On input, the time data read from RTC to convert\r
                      On output, the time converted to UEFI format\r
  @param   RegisterB  Value of Register B of RTC, indicating data mode\r
                      and hour format.\r
\r
  @retval  EFI_INVALID_PARAMETER  Parameters passed in are invalid.\r
  @retval  EFI_SUCCESS            Convert RTC time to EFI time successfully.\r
\r
**/\r
EFI_STATUS\r
ConvertRtcTimeToEfiTime (\r
  IN OUT EFI_TIME        *Time,\r
  IN     RTC_REGISTER_B  RegisterB\r
  )\r
{\r
  BOOLEAN  IsPM;\r
  UINT8    Century;\r
\r
  if ((Time->Hour & 0x80) != 0) {\r
    IsPM = TRUE;\r
  } else {\r
    IsPM = FALSE;\r
  }\r
\r
  Time->Hour = (UINT8)(Time->Hour & 0x7f);\r
\r
  if (RegisterB.Bits.Dm == 0) {\r
    Time->Year   = CheckAndConvertBcd8ToDecimal8 ((UINT8)Time->Year);\r
    Time->Month  = CheckAndConvertBcd8ToDecimal8 (Time->Month);\r
    Time->Day    = CheckAndConvertBcd8ToDecimal8 (Time->Day);\r
    Time->Hour   = CheckAndConvertBcd8ToDecimal8 (Time->Hour);\r
    Time->Minute = CheckAndConvertBcd8ToDecimal8 (Time->Minute);\r
    Time->Second = CheckAndConvertBcd8ToDecimal8 (Time->Second);\r
  }\r
\r
  if ((Time->Year == 0xff) || (Time->Month == 0xff) || (Time->Day == 0xff) ||\r
      (Time->Hour == 0xff) || (Time->Minute == 0xff) || (Time->Second == 0xff))\r
  {\r
    return EFI_INVALID_PARAMETER;\r
  }\r
\r
  //\r
  // For minimal/maximum year range [1970, 2069],\r
  //   Century is 19 if RTC year >= 70,\r
  //   Century is 20 otherwise.\r
  //\r
  Century = (UINT8)(PcdGet16 (PcdMinimalValidYear) / 100);\r
  if (Time->Year < PcdGet16 (PcdMinimalValidYear) % 100) {\r
    Century++;\r
  }\r
\r
  Time->Year = (UINT16)(Century * 100 + Time->Year);\r
\r
  //\r
  // If time is in 12 hour format, convert it to 24 hour format\r
  //\r
  if (RegisterB.Bits.Mil == 0) {\r
    if (IsPM && (Time->Hour < 12)) {\r
      Time->Hour = (UINT8)(Time->Hour + 12);\r
    }\r
\r
    if (!IsPM && (Time->Hour == 12)) {\r
      Time->Hour = 0;\r
    }\r
  }\r
\r
  Time->Nanosecond = 0;\r
\r
  return EFI_SUCCESS;\r
}\r
\r
/**\r
  Wait for a period for the RTC to be ready.\r
\r
  @param    Timeout  Tell how long it should take to wait.\r
\r
  @retval   EFI_DEVICE_ERROR   RTC device error.\r
  @retval   EFI_SUCCESS        RTC is updated and ready.\r
**/\r
EFI_STATUS\r
RtcWaitToUpdate (\r
  UINTN  Timeout\r
  )\r
{\r
  RTC_REGISTER_A  RegisterA;\r
  RTC_REGISTER_D  RegisterD;\r
\r
  //\r
  // See if the RTC is functioning correctly\r
  //\r
  RegisterD.Data = RtcRead (RTC_ADDRESS_REGISTER_D);\r
\r
  if (RegisterD.Bits.Vrt == 0) {\r
    return EFI_DEVICE_ERROR;\r
  }\r
\r
  //\r
  // Wait for up to 0.1 seconds for the RTC to be ready.\r
  //\r
  Timeout        = (Timeout / 10) + 1;\r
  RegisterA.Data = RtcRead (RTC_ADDRESS_REGISTER_A);\r
  while (RegisterA.Bits.Uip == 1 && Timeout > 0) {\r
    MicroSecondDelay (10);\r
    RegisterA.Data = RtcRead (RTC_ADDRESS_REGISTER_A);\r
    Timeout--;\r
  }\r
\r
  RegisterD.Data = RtcRead (RTC_ADDRESS_REGISTER_D);\r
  if ((Timeout == 0) || (RegisterD.Bits.Vrt == 0)) {\r
    return EFI_DEVICE_ERROR;\r
  }\r
\r
  return EFI_SUCCESS;\r
}\r
\r
/**\r
  See if all fields of a variable of EFI_TIME type is correct.\r
\r
  @param   Time   The time to be checked.\r
\r
  @retval  EFI_INVALID_PARAMETER  Some fields of Time are not correct.\r
  @retval  EFI_SUCCESS            Time is a valid EFI_TIME variable.\r
\r
**/\r
EFI_STATUS\r
RtcTimeFieldsValid (\r
  IN EFI_TIME  *Time\r
  )\r
{\r
  if ((Time->Year < PcdGet16 (PcdMinimalValidYear)) ||\r
      (Time->Year > PcdGet16 (PcdMaximalValidYear)) ||\r
      (Time->Month < 1) ||\r
      (Time->Month > 12) ||\r
      (!DayValid (Time)) ||\r
      (Time->Hour > 23) ||\r
      (Time->Minute > 59) ||\r
      (Time->Second > 59) ||\r
      (Time->Nanosecond > 999999999) ||\r
      (!((Time->TimeZone == EFI_UNSPECIFIED_TIMEZONE) || ((Time->TimeZone >= -1440) && (Time->TimeZone <= 1440)))) ||\r
      ((Time->Daylight & (~(EFI_TIME_ADJUST_DAYLIGHT | EFI_TIME_IN_DAYLIGHT))) != 0))\r
  {\r
    return EFI_INVALID_PARAMETER;\r
  }\r
\r
  return EFI_SUCCESS;\r
}\r
\r
/**\r
  See if field Day of an EFI_TIME is correct.\r
\r
  @param    Time   Its Day field is to be checked.\r
\r
  @retval   TRUE   Day field of Time is correct.\r
  @retval   FALSE  Day field of Time is NOT correct.\r
**/\r
BOOLEAN\r
DayValid (\r
  IN  EFI_TIME  *Time\r
  )\r
{\r
  //\r
  // The validity of Time->Month field should be checked before\r
  //\r
  ASSERT (Time->Month >= 1);\r
  ASSERT (Time->Month <= 12);\r
  if ((Time->Day < 1) ||\r
      (Time->Day > mDayOfMonth[Time->Month - 1]) ||\r
      ((Time->Month == 2) && (!IsLeapYear (Time) && (Time->Day > 28)))\r
      )\r
  {\r
    return FALSE;\r
  }\r
\r
  return TRUE;\r
}\r
\r
/**\r
  Check if it is a leap year.\r
\r
  @param    Time   The time to be checked.\r
\r
  @retval   TRUE   It is a leap year.\r
  @retval   FALSE  It is NOT a leap year.\r
**/\r
BOOLEAN\r
IsLeapYear (\r
  IN EFI_TIME  *Time\r
  )\r
{\r
  if (Time->Year % 4 == 0) {\r
    if (Time->Year % 100 == 0) {\r
      if (Time->Year % 400 == 0) {\r
        return TRUE;\r
      } else {\r
        return FALSE;\r
      }\r
    } else {\r
      return TRUE;\r
    }\r
  } else {\r
    return FALSE;\r
  }\r
}\r
\r
/**\r
  Converts time from EFI_TIME format defined by UEFI spec to RTC format.\r
\r
  This function converts time from EFI_TIME format defined by UEFI spec to RTC format.\r
  If data mode of RTC is BCD, then converts EFI_TIME to it.\r
  If RTC is in 12-hour format, then converts EFI_TIME to it.\r
\r
  @param   Time       On input, the time data read from UEFI to convert\r
                      On output, the time converted to RTC format\r
  @param   RegisterB  Value of Register B of RTC, indicating data mode\r
**/\r
VOID\r
ConvertEfiTimeToRtcTime (\r
  IN OUT EFI_TIME        *Time,\r
  IN     RTC_REGISTER_B  RegisterB\r
  )\r
{\r
  BOOLEAN  IsPM;\r
\r
  IsPM = TRUE;\r
  //\r
  // Adjust hour field if RTC is in 12 hour mode\r
  //\r
  if (RegisterB.Bits.Mil == 0) {\r
    if (Time->Hour < 12) {\r
      IsPM = FALSE;\r
    }\r
\r
    if (Time->Hour >= 13) {\r
      Time->Hour = (UINT8)(Time->Hour - 12);\r
    } else if (Time->Hour == 0) {\r
      Time->Hour = 12;\r
    }\r
  }\r
\r
  //\r
  // Set the Time/Date values.\r
  //\r
  Time->Year = (UINT16)(Time->Year % 100);\r
\r
  if (RegisterB.Bits.Dm == 0) {\r
    Time->Year   = DecimalToBcd8 ((UINT8)Time->Year);\r
    Time->Month  = DecimalToBcd8 (Time->Month);\r
    Time->Day    = DecimalToBcd8 (Time->Day);\r
    Time->Hour   = DecimalToBcd8 (Time->Hour);\r
    Time->Minute = DecimalToBcd8 (Time->Minute);\r
    Time->Second = DecimalToBcd8 (Time->Second);\r
  }\r
\r
  //\r
  // If we are in 12 hour mode and PM is set, then set bit 7 of the Hour field.\r
  //\r
  if ((RegisterB.Bits.Mil == 0) && IsPM) {\r
    Time->Hour = (UINT8)(Time->Hour | 0x80);\r
  }\r
}\r
\r
/**\r
  Compare the Hour, Minute and Second of the From time and the To time.\r
\r
  Only compare H/M/S in EFI_TIME and ignore other fields here.\r
\r
  @param From   the first time\r
  @param To     the second time\r
\r
  @return  >0   The H/M/S of the From time is later than those of To time\r
  @return  ==0  The H/M/S of the From time is same as those of To time\r
  @return  <0   The H/M/S of the From time is earlier than those of To time\r
**/\r
INTN\r
CompareHMS (\r
  IN EFI_TIME  *From,\r
  IN EFI_TIME  *To\r
  )\r
{\r
  if ((From->Hour > To->Hour) ||\r
      ((From->Hour == To->Hour) && (From->Minute > To->Minute)) ||\r
      ((From->Hour == To->Hour) && (From->Minute == To->Minute) && (From->Second > To->Second)))\r
  {\r
    return 1;\r
  } else if ((From->Hour == To->Hour) && (From->Minute == To->Minute) && (From->Second == To->Second)) {\r
    return 0;\r
  } else {\r
    return -1;\r
  }\r
}\r
\r
/**\r
  To check if second date is later than first date within 24 hours.\r
\r
  @param  From   the first date\r
  @param  To     the second date\r
\r
  @retval TRUE   From is previous to To within 24 hours.\r
  @retval FALSE  From is later, or it is previous to To more than 24 hours.\r
**/\r
BOOLEAN\r
IsWithinOneDay (\r
  IN EFI_TIME  *From,\r
  IN EFI_TIME  *To\r
  )\r
{\r
  BOOLEAN  Adjacent;\r
\r
  Adjacent = FALSE;\r
\r
  //\r
  // The validity of From->Month field should be checked before\r
  //\r
  ASSERT (From->Month >= 1);\r
  ASSERT (From->Month <= 12);\r
\r
  if (From->Year == To->Year) {\r
    if (From->Month == To->Month) {\r
      if ((From->Day + 1) == To->Day) {\r
        if ((CompareHMS (From, To) >= 0)) {\r
          Adjacent = TRUE;\r
        }\r
      } else if (From->Day == To->Day) {\r
        if ((CompareHMS (From, To) <= 0)) {\r
          Adjacent = TRUE;\r
        }\r
      }\r
    } else if (((From->Month + 1) == To->Month) && (To->Day == 1)) {\r
      if ((From->Month == 2) && !IsLeapYear (From)) {\r
        if (From->Day == 28) {\r
          if ((CompareHMS (From, To) >= 0)) {\r
            Adjacent = TRUE;\r
          }\r
        }\r
      } else if (From->Day == mDayOfMonth[From->Month - 1]) {\r
        if ((CompareHMS (From, To) >= 0)) {\r
          Adjacent = TRUE;\r
        }\r
      }\r
    }\r
  } else if (((From->Year + 1) == To->Year) &&\r
             (From->Month == 12) &&\r
             (From->Day   == 31) &&\r
             (To->Month   == 1)  &&\r
             (To->Day     == 1))\r
  {\r
    if ((CompareHMS (From, To) >= 0)) {\r
      Adjacent = TRUE;\r
    }\r
  }\r
\r
  return Adjacent;\r
}\r
\r
/**\r
  Get the century RTC address from the ACPI FADT table.\r
\r
  @return  The century RTC address or 0 if not found.\r
**/\r
UINT8\r
GetCenturyRtcAddress (\r
  VOID\r
  )\r
{\r
  EFI_ACPI_2_0_FIXED_ACPI_DESCRIPTION_TABLE  *Fadt;\r
\r
  Fadt = (EFI_ACPI_2_0_FIXED_ACPI_DESCRIPTION_TABLE *)EfiLocateFirstAcpiTable (\r
                                                        EFI_ACPI_2_0_FIXED_ACPI_DESCRIPTION_TABLE_SIGNATURE\r
                                                        );\r
\r
  if ((Fadt != NULL) &&\r
      (Fadt->Century > RTC_ADDRESS_REGISTER_D) && (Fadt->Century < 0x80)\r
      )\r
  {\r
    return Fadt->Century;\r
  } else {\r
    return 0;\r
  }\r
}\r
\r
/**\r
  Notification function of ACPI Table change.\r
\r
  This is a notification function registered on ACPI Table change event.\r
  It saves the Century address stored in ACPI FADT table.\r
\r
  @param  Event        Event whose notification function is being invoked.\r
  @param  Context      Pointer to the notification function's context.\r
\r
**/\r
VOID\r
EFIAPI\r
PcRtcAcpiTableChangeCallback (\r
  IN EFI_EVENT  Event,\r
  IN VOID       *Context\r
  )\r
{\r
  EFI_STATUS  Status;\r
  EFI_TIME    Time;\r
  UINT8       CenturyRtcAddress;\r
  UINT8       Century;\r
\r
  CenturyRtcAddress = GetCenturyRtcAddress ();\r
  if ((CenturyRtcAddress != 0) && (mModuleGlobal.CenturyRtcAddress != CenturyRtcAddress)) {\r
    mModuleGlobal.CenturyRtcAddress = CenturyRtcAddress;\r
    Status                          = PcRtcGetTime (&Time, NULL, &mModuleGlobal);\r
    if (!EFI_ERROR (Status)) {\r
      Century = (UINT8)(Time.Year / 100);\r
      Century = DecimalToBcd8 (Century);\r
      DEBUG ((DEBUG_INFO, "PcRtc: Write 0x%x to CMOS location 0x%x\n", Century, mModuleGlobal.CenturyRtcAddress));\r
      RtcWrite (mModuleGlobal.CenturyRtcAddress, Century);\r
    }\r
  }\r
}\r