/** @file
  RTC Architectural Protocol GUID as defined in DxeCis 0.96.

Copyright (c) 2006 - 2007, Intel Corporation
All rights reserved. This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution.  The full text of the license may be found at
http://opensource.org/licenses/bsd-license.php

THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

**/

#include "PcRtc.h"

STATIC
INTN
CompareHMS (
  IN EFI_TIME   *From,
  IN EFI_TIME   *To
  );

STATIC
BOOLEAN
IsWithinOneDay (
  IN EFI_TIME   *From,
  IN EFI_TIME   *To
  );

STATIC
UINT8
RtcRead (
  IN  UINT8 Address
  )
/*++

Routine Description:

  GC_TODO: Add function description

Arguments:

  Address - GC_TODO: add argument description

Returns:

  GC_TODO: add return values

--*/
{
  IoWrite8 (PCAT_RTC_ADDRESS_REGISTER, (UINT8) (Address | (UINT8) (IoRead8 (PCAT_RTC_ADDRESS_REGISTER) & 0x80)));
  return IoRead8 (PCAT_RTC_DATA_REGISTER);
}

STATIC
VOID
RtcWrite (
  IN  UINT8   Address,
  IN  UINT8   Data
  )
/*++

Routine Description:

  GC_TODO: Add function description

Arguments:

  Address - GC_TODO: add argument description
  Data    - GC_TODO: add argument description

Returns:

  GC_TODO: add return values

--*/
{
  IoWrite8 (PCAT_RTC_ADDRESS_REGISTER, (UINT8) (Address | (UINT8) (IoRead8 (PCAT_RTC_ADDRESS_REGISTER) & 0x80)));
  IoWrite8 (PCAT_RTC_DATA_REGISTER, Data);
}

EFI_STATUS
PcRtcInit (
  IN PC_RTC_MODULE_GLOBALS  *Global
  )
/*++

Routine Description:

  GC_TODO: Add function description

Arguments:

  Global  - GC_TODO: add argument description

Returns:

  EFI_DEVICE_ERROR - GC_TODO: Add description for return value
  EFI_SUCCESS - GC_TODO: Add description for return value

--*/
{
  EFI_STATUS      Status;
  RTC_REGISTER_A  RegisterA;
  RTC_REGISTER_B  RegisterB;
  RTC_REGISTER_D  RegisterD;
  UINT8           Century;
  EFI_TIME        Time;
  UINTN           DataSize;
  UINT32          TimerVar;

  //
  // Acquire RTC Lock to make access to RTC atomic
  //
  //BugBug: the EfiAtRuntime should be encapsulated in EfiAcquireLock or
  //        provide a new instance for EfiAcquireLock, say, RtEfiAcquireLock
  if (!EfiAtRuntime ()) {
  EfiAcquireLock (&Global->RtcLock);
  }
  //
  // Initialize RTC Register
  //
  // Make sure Division Chain is properly configured,
  // or RTC clock won't "tick" -- time won't increment
  //
  RegisterA.Data = RTC_INIT_REGISTER_A;
  RtcWrite (RTC_ADDRESS_REGISTER_A, RegisterA.Data);

  //
  // Read Register B
  //
  RegisterB.Data = RtcRead (RTC_ADDRESS_REGISTER_B);

  //
  // Clear RTC flag register
  //
  RtcRead (RTC_ADDRESS_REGISTER_C);

  //
  // Clear RTC register D
  //
  RegisterD.Data = RTC_INIT_REGISTER_D;
  RtcWrite (RTC_ADDRESS_REGISTER_D, RegisterD.Data);

  //
  // Wait for up to 0.1 seconds for the RTC to be updated
  //
  Status = RtcWaitToUpdate (100000);
  if (EFI_ERROR (Status)) {
  	//BugBug: the EfiAtRuntime should be encapsulated in EfiAcquireLock or
    //        provide a new instance for EfiAcquireLock, say, RtEfiAcquireLock
    if (!EfiAtRuntime ()) {
    EfiReleaseLock (&Global->RtcLock);
    }
    return EFI_DEVICE_ERROR;
  }
  //
  // Get the Time/Date/Daylight Savings values.
  //
  Time.Second = RtcRead (RTC_ADDRESS_SECONDS);
  Time.Minute = RtcRead (RTC_ADDRESS_MINUTES);
  Time.Hour   = RtcRead (RTC_ADDRESS_HOURS);
  Time.Day    = RtcRead (RTC_ADDRESS_DAY_OF_THE_MONTH);
  Time.Month  = RtcRead (RTC_ADDRESS_MONTH);
  Time.Year   = RtcRead (RTC_ADDRESS_YEAR);

  if (RtcTestCenturyRegister () == EFI_SUCCESS) {
    Century = (UINT8) (RtcRead (RTC_ADDRESS_CENTURY) & 0x7f);
  } else {
    Century = RtcRead (RTC_ADDRESS_CENTURY);
  }

  //
  // Set RTC configuration after get original time
  // The value of bit AIE should be reserved.
  //
  RtcWrite (RTC_ADDRESS_REGISTER_B, (UINT8)(RTC_INIT_REGISTER_B | (RegisterB.Data & BIT5)));

  //
  // Release RTC Lock.
  //
  //BugBug: the EfiAtRuntime should be encapsulated in EfiAcquireLock or
  //        provide a new instance for EfiAcquireLock, say, RtEfiAcquireLock
  //
  if (!EfiAtRuntime ()) {
  EfiReleaseLock (&Global->RtcLock);
  }
 
  //
  // Validate time fields
  //
  Status = ConvertRtcTimeToEfiTime (&Time, Century, RegisterB);
  if (!EFI_ERROR (Status)) {
    Status = RtcTimeFieldsValid (&Time);
  }
  if (EFI_ERROR (Status)) {
    Time.Second = RTC_INIT_SECOND;
    Time.Minute = RTC_INIT_MINUTE;
    Time.Hour   = RTC_INIT_HOUR;
    Time.Day    = RTC_INIT_DAY;
    Time.Month  = RTC_INIT_MONTH;
    Time.Year   = RTC_INIT_YEAR;
  }
  //
  // Get the data of Daylight saving and time zone, if they have been
  // stored in NV variable during previous boot.
  //
  DataSize = sizeof (UINT32);
  Status = EfiGetVariable (
             L"TimerVar",
             &gEfiGenericPlatformVariableGuid,
             NULL,
             &DataSize,
             (VOID *) &TimerVar
             );
  if (!EFI_ERROR (Status)) {
    Global->SavedTimeZone = (INT16) TimerVar;
    Global->Daylight      = (UINT8) (TimerVar >> 16);

    Time.TimeZone = Global->SavedTimeZone;
    Time.Daylight = Global->Daylight;
  }
  //
  // Reset time value according to new RTC configuration
  //
  PcRtcSetTime (&Time, Global);

  return EFI_SUCCESS;
}

EFI_STATUS
PcRtcGetTime (
  OUT EFI_TIME              *Time,
  IN  EFI_TIME_CAPABILITIES *Capabilities,
  IN  PC_RTC_MODULE_GLOBALS *Global
  )
/*++

Routine Description:

  Arguments:

  Returns:
--*/
// GC_TODO:    Time - add argument and description to function comment
// GC_TODO:    Capabilities - add argument and description to function comment
// GC_TODO:    Global - add argument and description to function comment
// GC_TODO:    EFI_INVALID_PARAMETER - add return value to function comment
// GC_TODO:    EFI_DEVICE_ERROR - add return value to function comment
// GC_TODO:    EFI_SUCCESS - add return value to function comment
{
  EFI_STATUS      Status;
  RTC_REGISTER_B  RegisterB;
  UINT8           Century;

  //
  // Check parameters for null pointer
  //
  if (Time == NULL) {
    return EFI_INVALID_PARAMETER;

  }
  //
  // Acquire RTC Lock to make access to RTC atomic
  //
  //BugBug: the EfiAtRuntime should be encapsulated in EfiAcquireLock or
  //        provide a new instance for EfiAcquireLock, say, RtEfiAcquireLock
  if (!EfiAtRuntime ()) {
  EfiAcquireLock (&Global->RtcLock);
  }
  //
  // Wait for up to 0.1 seconds for the RTC to be updated
  //
  Status = RtcWaitToUpdate (100000);
  if (EFI_ERROR (Status)) {
  	  //BugBug: the EfiAtRuntime should be encapsulated in EfiReleaseLock or
      //        provide a new instance for EfiReleaseLock, say, RtEfiReleaseLock
      if (!EfiAtRuntime ()) {
    EfiReleaseLock (&Global->RtcLock);
      }
    return Status;
  }
  //
  // Read Register B
  //
  RegisterB.Data = RtcRead (RTC_ADDRESS_REGISTER_B);

  //
  // Get the Time/Date/Daylight Savings values.
  //
  Time->Second  = RtcRead (RTC_ADDRESS_SECONDS);
  Time->Minute  = RtcRead (RTC_ADDRESS_MINUTES);
  Time->Hour    = RtcRead (RTC_ADDRESS_HOURS);
  Time->Day     = RtcRead (RTC_ADDRESS_DAY_OF_THE_MONTH);
  Time->Month   = RtcRead (RTC_ADDRESS_MONTH);
  Time->Year    = RtcRead (RTC_ADDRESS_YEAR);

  if (RtcTestCenturyRegister () == EFI_SUCCESS) {
    Century = (UINT8) (RtcRead (RTC_ADDRESS_CENTURY) & 0x7f);
  } else {
    Century = RtcRead (RTC_ADDRESS_CENTURY);
  }

  //
  // Release RTC Lock.
  //
  //BugBug: the EfiAtRuntime should be encapsulated in EfiReleaseLock or
  //        provide a new instance for EfiReleaseLock, say, RtEfiReleaseLock
  if (!EfiAtRuntime ()) {
  EfiReleaseLock (&Global->RtcLock);
  }
  //
  // Get the variable that containts the TimeZone and Daylight fields
  //
  Time->TimeZone  = Global->SavedTimeZone;
  Time->Daylight  = Global->Daylight;

  //
  // Make sure all field values are in correct range
  //
  Status = ConvertRtcTimeToEfiTime (Time, Century, RegisterB);
  if (!EFI_ERROR (Status)) {
    Status = RtcTimeFieldsValid (Time);
  }
  if (EFI_ERROR (Status)) {
    return EFI_DEVICE_ERROR;
  }
  //
  //  Fill in Capabilities if it was passed in
  //
  if (Capabilities) {
    Capabilities->Resolution = 1;
    //
    // 1 hertz
    //
    Capabilities->Accuracy = 50000000;
    //
    // 50 ppm
    //
    Capabilities->SetsToZero = FALSE;
  }

  return EFI_SUCCESS;
}

EFI_STATUS
PcRtcSetTime (
  IN EFI_TIME                *Time,
  IN PC_RTC_MODULE_GLOBALS   *Global
  )
/*++

Routine Description:

  Arguments:

  Returns:
--*/
// GC_TODO:    Time - add argument and description to function comment
// GC_TODO:    Global - add argument and description to function comment
// GC_TODO:    EFI_INVALID_PARAMETER - add return value to function comment
{
  EFI_STATUS      Status;
  EFI_TIME        RtcTime;
  RTC_REGISTER_B  RegisterB;
  UINT8           Century;
  UINT32          TimerVar;

  if (Time == NULL) {
    return EFI_INVALID_PARAMETER;
  }
  //
  // Make sure that the time fields are valid
  //
  Status = RtcTimeFieldsValid (Time);
  if (EFI_ERROR (Status)) {
    return Status;
  }

  CopyMem (&RtcTime, Time, sizeof (EFI_TIME));

  //
  // Acquire RTC Lock to make access to RTC atomic
  //
  //BugBug: the EfiAtRuntime should be encapsulated in EfiAcquireLock or
  //        provide a new instance for EfiAcquireLock, say, RtEfiAcquireLock
  if (!EfiAtRuntime ()) {
  EfiAcquireLock (&Global->RtcLock);
  }
  //
  // Wait for up to 0.1 seconds for the RTC to be updated
  //
  Status = RtcWaitToUpdate (100000);
  if (EFI_ERROR (Status)) {
  	 //BugBug: the EfiAtRuntime should be encapsulated in EfiReleaseLock or
     //        provide a new instance for EfiReleaseLock, say, RtEfiReleaseLock
     if (!EfiAtRuntime ()) {
    EfiReleaseLock (&Global->RtcLock);
     }
    return Status;
  }
  //
  // Read Register B, and inhibit updates of the RTC
  //
  RegisterB.Data      = RtcRead (RTC_ADDRESS_REGISTER_B);
  RegisterB.Bits.SET  = 1;
  RtcWrite (RTC_ADDRESS_REGISTER_B, RegisterB.Data);

  ConvertEfiTimeToRtcTime (&RtcTime, RegisterB, &Century);

  RtcWrite (RTC_ADDRESS_SECONDS, RtcTime.Second);
  RtcWrite (RTC_ADDRESS_MINUTES, RtcTime.Minute);
  RtcWrite (RTC_ADDRESS_HOURS, RtcTime.Hour);
  RtcWrite (RTC_ADDRESS_DAY_OF_THE_MONTH, RtcTime.Day);
  RtcWrite (RTC_ADDRESS_MONTH, RtcTime.Month);
  RtcWrite (RTC_ADDRESS_YEAR, (UINT8) RtcTime.Year);
  if (RtcTestCenturyRegister () == EFI_SUCCESS) {
    Century = (UINT8) ((Century & 0x7f) | (RtcRead (RTC_ADDRESS_CENTURY) & 0x80));
  }

  RtcWrite (RTC_ADDRESS_CENTURY, Century);

  //
  // Allow updates of the RTC registers
  //
  RegisterB.Bits.SET = 0;
  RtcWrite (RTC_ADDRESS_REGISTER_B, RegisterB.Data);

  //
  // Release RTC Lock.
  //
  //BugBug: the EfiAtRuntime should be encapsulated in EfiReleaseLock or
  //        provide a new instance for EfiReleaseLock, say, RtEfiReleaseLock
  if (!EfiAtRuntime ()) {
  EfiReleaseLock (&Global->RtcLock);
  }
  //
  // Set the variable that containts the TimeZone and Daylight fields
  //
  Global->SavedTimeZone = Time->TimeZone;
  Global->Daylight      = Time->Daylight;

  TimerVar = Time->Daylight;
  TimerVar = (UINT32) ((TimerVar << 16) | Time->TimeZone);
  Status =  EfiSetVariable (
              L"TimerVar",
              &gEfiGenericPlatformVariableGuid,
              EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_NON_VOLATILE,
              sizeof (TimerVar),
              &TimerVar
              );
  ASSERT_EFI_ERROR (Status);

  return EFI_SUCCESS;
}

EFI_STATUS
PcRtcGetWakeupTime (
  OUT BOOLEAN                *Enabled,
  OUT BOOLEAN                *Pending,
  OUT EFI_TIME               *Time,
  IN PC_RTC_MODULE_GLOBALS   *Global
  )
/*++

Routine Description:

  Arguments:



Returns:
--*/
// GC_TODO:    Enabled - add argument and description to function comment
// GC_TODO:    Pending - add argument and description to function comment
// GC_TODO:    Time - add argument and description to function comment
// GC_TODO:    Global - add argument and description to function comment
// GC_TODO:    EFI_INVALID_PARAMETER - add return value to function comment
// GC_TODO:    EFI_DEVICE_ERROR - add return value to function comment
// GC_TODO:    EFI_DEVICE_ERROR - add return value to function comment
// GC_TODO:    EFI_SUCCESS - add return value to function comment
{
  EFI_STATUS      Status;
  RTC_REGISTER_B  RegisterB;
  RTC_REGISTER_C  RegisterC;
  UINT8           Century;

  //
  // Check paramters for null pointers
  //
  if ((Enabled == NULL) || (Pending == NULL) || (Time == NULL)) {
    return EFI_INVALID_PARAMETER;

  }
  //
  // Acquire RTC Lock to make access to RTC atomic
  //
  //BugBug: the EfiAtRuntime should be encapsulated in EfiAcquireLock or
  //        provide a new instance for EfiAcquireLock, say, RtEfiAcquireLock
  if (!EfiAtRuntime ()) {
  EfiAcquireLock (&Global->RtcLock);
  }
  //
  // Wait for up to 0.1 seconds for the RTC to be updated
  //
  Status = RtcWaitToUpdate (100000);
  if (EFI_ERROR (Status)) {
  	//BugBug: the EfiAtRuntime should be encapsulated in EfiReleaseLock or
    //        provide a new instance for EfiReleaseLock, say, RtEfiReleaseLock
    if (!EfiAtRuntime ()) {
    EfiReleaseLock (&Global->RtcLock);
    }
    return EFI_DEVICE_ERROR;
  }
  //
  // Read Register B and Register C
  //
  RegisterB.Data  = RtcRead (RTC_ADDRESS_REGISTER_B);
  RegisterC.Data  = RtcRead (RTC_ADDRESS_REGISTER_C);

  //
  // Get the Time/Date/Daylight Savings values.
  //
  *Enabled = RegisterB.Bits.AIE;
  if (*Enabled) {
    Time->Second  = RtcRead (RTC_ADDRESS_SECONDS_ALARM);
    Time->Minute  = RtcRead (RTC_ADDRESS_MINUTES_ALARM);
    Time->Hour    = RtcRead (RTC_ADDRESS_HOURS_ALARM);
    Time->Day     = RtcRead (RTC_ADDRESS_DAY_OF_THE_MONTH);
    Time->Month   = RtcRead (RTC_ADDRESS_MONTH);
    Time->Year    = RtcRead (RTC_ADDRESS_YEAR);
  } else {
    Time->Second  = 0;
    Time->Minute  = 0;
    Time->Hour    = 0;
    Time->Day     = RtcRead (RTC_ADDRESS_DAY_OF_THE_MONTH);
    Time->Month   = RtcRead (RTC_ADDRESS_MONTH);
    Time->Year    = RtcRead (RTC_ADDRESS_YEAR);
  }

  if (RtcTestCenturyRegister () == EFI_SUCCESS) {
    Century = (UINT8) (RtcRead (RTC_ADDRESS_CENTURY) & 0x7f);
  } else {
    Century = RtcRead (RTC_ADDRESS_CENTURY);
  }

  //
  // Release RTC Lock.
  //
  //BugBug: the EfiAtRuntime should be encapsulated in EfiReleaseLock or
  //        provide a new instance for EfiReleaseLock, say, RtEfiReleaseLock
  if (!EfiAtRuntime ()) {
  EfiReleaseLock (&Global->RtcLock);
  }
  //
  // Make sure all field values are in correct range
  //
  Status = ConvertRtcTimeToEfiTime (Time, Century, RegisterB);
  if (!EFI_ERROR (Status)) {
    Status = RtcTimeFieldsValid (Time);
  }
  if (EFI_ERROR (Status)) {
    return EFI_DEVICE_ERROR;
  }

  *Pending = RegisterC.Bits.AF;

  return EFI_SUCCESS;
}

EFI_STATUS
PcRtcSetWakeupTime (
  IN BOOLEAN                Enable,
  OUT EFI_TIME              *Time,
  IN PC_RTC_MODULE_GLOBALS  *Global
  )
/*++

Routine Description:

  Arguments:



Returns:
--*/
// GC_TODO:    Enable - add argument and description to function comment
// GC_TODO:    Time - add argument and description to function comment
// GC_TODO:    Global - add argument and description to function comment
// GC_TODO:    EFI_INVALID_PARAMETER - add return value to function comment
// GC_TODO:    EFI_INVALID_PARAMETER - add return value to function comment
// GC_TODO:    EFI_UNSUPPORTED - add return value to function comment
// GC_TODO:    EFI_DEVICE_ERROR - add return value to function comment
// GC_TODO:    EFI_SUCCESS - add return value to function comment
{
  EFI_STATUS            Status;
  EFI_TIME              RtcTime;
  RTC_REGISTER_B        RegisterB;
  UINT8                 Century;
  EFI_TIME_CAPABILITIES Capabilities;

  if (Enable) {

    if (Time == NULL) {
      return EFI_INVALID_PARAMETER;
    }
    //
    // Make sure that the time fields are valid
    //
    Status = RtcTimeFieldsValid (Time);
    if (EFI_ERROR (Status)) {
      return EFI_INVALID_PARAMETER;
    }
    //
    // Just support set alarm time within 24 hours
    //
    PcRtcGetTime (&RtcTime, &Capabilities, Global);
    if (!IsWithinOneDay (&RtcTime, Time)) {
      return EFI_UNSUPPORTED;
    }
    //
    // Make a local copy of the time and date
    //
    CopyMem (&RtcTime, Time, sizeof (EFI_TIME));

  }
  //
  // Acquire RTC Lock to make access to RTC atomic
  //
  //BugBug: the EfiAtRuntime should be encapsulated in EfiAcquireLock or
  //        provide a new instance for EfiAcquireLock, say, RtEfiAcquireLock
  if (!EfiAtRuntime ()) {
  EfiAcquireLock (&Global->RtcLock);
  }
  //
  // Wait for up to 0.1 seconds for the RTC to be updated
  //
  Status = RtcWaitToUpdate (100000);
  if (EFI_ERROR (Status)) {
    //BugBug: the EfiAtRuntime should be encapsulated in EfiReleaseLock or
    //        provide a new instance for EfiReleaseLock, say, RtEfiReleaseLock
    if (!EfiAtRuntime ()) {
    EfiReleaseLock (&Global->RtcLock);
    }
    return EFI_DEVICE_ERROR;
  }
  //
  // Read Register B, and inhibit updates of the RTC
  //
  RegisterB.Data      = RtcRead (RTC_ADDRESS_REGISTER_B);

  RegisterB.Bits.SET  = 1;
  RtcWrite (RTC_ADDRESS_REGISTER_B, RegisterB.Data);

  if (Enable) {
    ConvertEfiTimeToRtcTime (&RtcTime, RegisterB, &Century);

    //
    // Set RTC alarm time
    //
    RtcWrite (RTC_ADDRESS_SECONDS_ALARM, RtcTime.Second);
    RtcWrite (RTC_ADDRESS_MINUTES_ALARM, RtcTime.Minute);
    RtcWrite (RTC_ADDRESS_HOURS_ALARM, RtcTime.Hour);

    RegisterB.Bits.AIE = 1;

  } else {
    RegisterB.Bits.AIE = 0;
  }
  //
  // Allow updates of the RTC registers
  //
  RegisterB.Bits.SET = 0;
  RtcWrite (RTC_ADDRESS_REGISTER_B, RegisterB.Data);

  //
  // Release RTC Lock.
  //
  //BugBug: the EfiAtRuntime should be encapsulated in EfiReleaseLock or
  //        provide a new instance for EfiReleaseLock, say, RtEfiReleaseLock
  if (!EfiAtRuntime ()) {
  EfiReleaseLock (&Global->RtcLock);
  }
  return EFI_SUCCESS;
}

EFI_STATUS
RtcTestCenturyRegister (
  VOID
  )
/*++

Routine Description:

  Arguments:



Returns:
--*/
// GC_TODO:    EFI_SUCCESS - add return value to function comment
// GC_TODO:    EFI_DEVICE_ERROR - add return value to function comment
{
  UINT8 Century;
  UINT8 Temp;

  Century = RtcRead (RTC_ADDRESS_CENTURY);
  //
  //  RtcWrite (RTC_ADDRESS_CENTURY, 0x00);
  //
  Temp = (UINT8) (RtcRead (RTC_ADDRESS_CENTURY) & 0x7f);
  RtcWrite (RTC_ADDRESS_CENTURY, Century);
  if (Temp == 0x19 || Temp == 0x20) {
    return EFI_SUCCESS;
  }

  return EFI_DEVICE_ERROR;
}

/**
  Checks an 8-bit BCD value, and converts to an 8-bit value if valid.

  This function checks the 8-bit BCD value specified by Value.
  If valid, the function converts it to an 8-bit value and returns it.
  Otherwise, return 0xff.

  @param  Value The 8-bit BCD value to check and convert

  @return The 8-bit value converted.
          0xff if Value is invalid.

**/
UINT8
CheckAndConvertBcd8ToDecimal8 (
  IN  UINT8  Value
  )
{
  if ((Value < 0xa0) && ((Value & 0xf) < 0xa)) {
    return BcdToDecimal8 (Value);
  }

  return 0xff;
}

/**
  Converts time read from RTC to EFI_TIME format defined by UEFI spec.

  This function converts raw time data read from RTC to the EFI_TIME format
  defined by UEFI spec.
  If data mode of RTC is BCD, then converts it to decimal,
  If RTC is in 12-hour format, then converts it to 24-hour format.

  @param   Time       On input, the time data read from RTC to convert
                      On output, the time converted to UEFI format
  @param   Century    Value of century read from RTC.
  @param   RegisterB  Value of Register B of RTC, indicating data mode
                      and hour format.

**/
EFI_STATUS
ConvertRtcTimeToEfiTime (
  IN OUT EFI_TIME        *Time,
  IN     UINT8           Century,
  IN     RTC_REGISTER_B  RegisterB
  )
{
  BOOLEAN PM;

  if ((Time->Hour) & 0x80) {
    PM = TRUE;
  } else {
    PM = FALSE;
  }

  Time->Hour = (UINT8) (Time->Hour & 0x7f);

  if (RegisterB.Bits.DM == 0) {
    Time->Year    = CheckAndConvertBcd8ToDecimal8 ((UINT8) Time->Year);
    Time->Month   = CheckAndConvertBcd8ToDecimal8 (Time->Month);
    Time->Day     = CheckAndConvertBcd8ToDecimal8 (Time->Day);
    Time->Hour    = CheckAndConvertBcd8ToDecimal8 (Time->Hour);
    Time->Minute  = CheckAndConvertBcd8ToDecimal8 (Time->Minute);
    Time->Second  = CheckAndConvertBcd8ToDecimal8 (Time->Second);
    Century       = CheckAndConvertBcd8ToDecimal8 (Century);
  }

  if (Time->Year == 0xff || Time->Month == 0xff || Time->Day == 0xff ||
      Time->Hour == 0xff || Time->Minute == 0xff || Time->Second == 0xff ||
      Century == 0xff) {
    return EFI_INVALID_PARAMETER;
  }

  Time->Year = (UINT16) (Century * 100 + Time->Year);

  //
  // If time is in 12 hour format, convert it to 24 hour format
  //
  if (RegisterB.Bits.MIL == 0) {
    if (PM && Time->Hour < 12) {
      Time->Hour = (UINT8) (Time->Hour + 12);
    }

    if (!PM && Time->Hour == 12) {
      Time->Hour = 0;
    }
  }

  Time->Nanosecond  = 0;
  Time->TimeZone    = EFI_UNSPECIFIED_TIMEZONE;
  Time->Daylight    = 0;

  return EFI_SUCCESS;
}

EFI_STATUS
RtcWaitToUpdate (
  UINTN Timeout
  )
/*++

Routine Description:

  Arguments:


Returns:
--*/
// GC_TODO:    Timeout - add argument and description to function comment
// GC_TODO:    EFI_DEVICE_ERROR - add return value to function comment
// GC_TODO:    EFI_DEVICE_ERROR - add return value to function comment
// GC_TODO:    EFI_SUCCESS - add return value to function comment
{
  RTC_REGISTER_A  RegisterA;
  RTC_REGISTER_D  RegisterD;

  //
  // See if the RTC is functioning correctly
  //
  RegisterD.Data = RtcRead (RTC_ADDRESS_REGISTER_D);

  if (RegisterD.Bits.VRT == 0) {
    return EFI_DEVICE_ERROR;
  }
  //
  // Wait for up to 0.1 seconds for the RTC to be ready.
  //
  Timeout         = (Timeout / 10) + 1;
  RegisterA.Data  = RtcRead (RTC_ADDRESS_REGISTER_A);
  while (RegisterA.Bits.UIP == 1 && Timeout > 0) {
    MicroSecondDelay (10);
    RegisterA.Data = RtcRead (RTC_ADDRESS_REGISTER_A);
    Timeout--;
  }

  RegisterD.Data = RtcRead (RTC_ADDRESS_REGISTER_D);
  if (Timeout == 0 || RegisterD.Bits.VRT == 0) {
    return EFI_DEVICE_ERROR;
  }

  return EFI_SUCCESS;
}

EFI_STATUS
RtcTimeFieldsValid (
  IN EFI_TIME *Time
  )
/*++

Routine Description:

  Arguments:

  Returns:
--*/
// GC_TODO:    Time - add argument and description to function comment
// GC_TODO:    EFI_INVALID_PARAMETER - add return value to function comment
// GC_TODO:    EFI_SUCCESS - add return value to function comment
{
  if (Time->Year < 1998 ||
      Time->Year > 2099 ||
      Time->Month < 1 ||
      Time->Month > 12 ||
      (!DayValid (Time)) ||
      Time->Hour > 23 ||
      Time->Minute > 59 ||
      Time->Second > 59 ||
      Time->Nanosecond > 999999999 ||
      (!(Time->TimeZone == EFI_UNSPECIFIED_TIMEZONE || (Time->TimeZone >= -1440 && Time->TimeZone <= 1440))) ||
      (Time->Daylight & (~(EFI_TIME_ADJUST_DAYLIGHT | EFI_TIME_IN_DAYLIGHT)))
      ) {
    return EFI_INVALID_PARAMETER;
  }

  return EFI_SUCCESS;
}

BOOLEAN
DayValid (
  IN  EFI_TIME  *Time
  )
/*++

Routine Description:

  GC_TODO: Add function description

Arguments:

  Time  - GC_TODO: add argument description

Returns:

  GC_TODO: add return values

--*/
{
  INTN  DayOfMonth[12];

  DayOfMonth[0] = 31;
  DayOfMonth[1] = 29;
  DayOfMonth[2] = 31;
  DayOfMonth[3] = 30;
  DayOfMonth[4] = 31;
  DayOfMonth[5] = 30;
  DayOfMonth[6] = 31;
  DayOfMonth[7] = 31;
  DayOfMonth[8] = 30;
  DayOfMonth[9] = 31;
  DayOfMonth[10] = 30;
  DayOfMonth[11] = 31;

  if (Time->Day < 1 ||
      Time->Day > DayOfMonth[Time->Month - 1] ||
      (Time->Month == 2 && (!IsLeapYear (Time) && Time->Day > 28))
      ) {
    return FALSE;
  }

  return TRUE;
}

BOOLEAN
IsLeapYear (
  IN EFI_TIME   *Time
  )
/*++

Routine Description:

  GC_TODO: Add function description

Arguments:

  Time  - GC_TODO: add argument description

Returns:

  GC_TODO: add return values

--*/
{
  if (Time->Year % 4 == 0) {
    if (Time->Year % 100 == 0) {
      if (Time->Year % 400 == 0) {
        return TRUE;
      } else {
        return FALSE;
      }
    } else {
      return TRUE;
    }
  } else {
    return FALSE;
  }
}

VOID
ConvertEfiTimeToRtcTime (
  IN EFI_TIME       *Time,
  IN RTC_REGISTER_B RegisterB,
  IN UINT8          *Century
  )
/*++

Routine Description:

  Arguments:


Returns:
--*/
// GC_TODO:    Time - add argument and description to function comment
// GC_TODO:    RegisterB - add argument and description to function comment
// GC_TODO:    Century - add argument and description to function comment
{
  BOOLEAN PM;

  PM = TRUE;
  //
  // Adjust hour field if RTC in in 12 hour mode
  //
  if (RegisterB.Bits.MIL == 0) {
    if (Time->Hour < 12) {
      PM = FALSE;
    }

    if (Time->Hour >= 13) {
      Time->Hour = (UINT8) (Time->Hour - 12);
    } else if (Time->Hour == 0) {
      Time->Hour = 12;
    }
  }
  //
  // Set the Time/Date/Daylight Savings values.
  //
  *Century    = DecimalToBcd8 ((UINT8) (Time->Year / 100));

  Time->Year  = (UINT16) (Time->Year % 100);

  if (RegisterB.Bits.DM == 0) {
    Time->Year    = DecimalToBcd8 ((UINT8) Time->Year);
    Time->Month   = DecimalToBcd8 (Time->Month);
    Time->Day     = DecimalToBcd8 (Time->Day);
    Time->Hour    = DecimalToBcd8 (Time->Hour);
    Time->Minute  = DecimalToBcd8 (Time->Minute);
    Time->Second  = DecimalToBcd8 (Time->Second);
  }
  //
  // If we are in 12 hour mode and PM is set, then set bit 7 of the Hour field.
  //
  if (RegisterB.Bits.MIL == 0 && PM) {
    Time->Hour = (UINT8) (Time->Hour | 0x80);
  }
}

STATIC
INTN
CompareHMS (
  IN EFI_TIME   *From,
  IN EFI_TIME   *To
  )
/*++

Routine Description:

  Compare the Hour, Minute and Second of the 'From' time and the 'To' time.
  Only compare H/M/S in EFI_TIME and ignore other fields here.

Arguments:

  From  -   the first time
  To    -   the second time

Returns:

  >0   : The H/M/S of the 'From' time is later than those of 'To' time
  ==0  : The H/M/S of the 'From' time is same as those of 'To' time
  <0   : The H/M/S of the 'From' time is earlier than those of 'To' time

--*/
{
  if ((From->Hour > To->Hour) ||
     ((From->Hour == To->Hour) && (From->Minute > To->Minute)) ||
     ((From->Hour == To->Hour) && (From->Minute == To->Minute) && (From->Second > To->Second))) {
    return 1;
  } else if ((From->Hour == To->Hour) && (From->Minute == To->Minute) && (From->Second == To->Second)) {
    return 0;
  } else {
    return -1;
  }
}

STATIC
BOOLEAN
IsWithinOneDay (
  IN EFI_TIME  *From,
  IN EFI_TIME  *To
  )
/*++

Routine Description:

  Judge whether two days are adjacent.

Arguments:

  From  -   the first day
  To    -   the second day

Returns:

  TRUE  -   The interval of two days are within one day.
  FALSE -   The interval of two days exceed ony day or parameter error.

--*/
{
  UINT8   DayOfMonth[12];
  BOOLEAN Adjacent;

  DayOfMonth[0] = 31;
  DayOfMonth[1] = 29;
  DayOfMonth[2] = 31;
  DayOfMonth[3] = 30;
  DayOfMonth[4] = 31;
  DayOfMonth[5] = 30;
  DayOfMonth[6] = 31;
  DayOfMonth[7] = 31;
  DayOfMonth[8] = 30;
  DayOfMonth[9] = 31;
  DayOfMonth[10] = 30;
  DayOfMonth[11] = 31;

  Adjacent = FALSE;

  if (From->Year == To->Year) {
    if (From->Month == To->Month) {
      if ((From->Day + 1) == To->Day) {
        if ((CompareHMS(From, To) >= 0)) {
          Adjacent = TRUE;
        }
      } else if (From->Day == To->Day) {
        if ((CompareHMS(From, To) <= 0)) {
          Adjacent = TRUE;
        }
      }
    } else if (((From->Month + 1) == To->Month) && (To->Day == 1)) {
      if ((From->Month == 2) && !IsLeapYear(From)) {
        if (From->Day == 28) {
          if ((CompareHMS(From, To) >= 0)) {
            Adjacent = TRUE;
          }
        }
      } else if (From->Day == DayOfMonth[From->Month - 1]) {
        if ((CompareHMS(From, To) >= 0)) {
           Adjacent = TRUE;
        }
      }
    }
  } else if (((From->Year + 1) == To->Year) &&
             (From->Month == 12) &&
             (From->Day   == 31) &&
             (To->Month   == 1)  &&
             (To->Day     == 1)) {
    if ((CompareHMS(From, To) >= 0)) {
      Adjacent = TRUE;
    }
  }

  return Adjacent;
}