PcAtChipsetPkg/PcRtc: Fix a Y2K bug

The original driver cannot handle the case when system time runs from 1999/12/31 23:59:59
to 2000/1/1 0:0:0.
A simple test to set system time to 1999/12/31 23:59:59 can expose this bug.
The patch limits the driver to only support year in 100 range and decide the century value based
on the supporting range: Century either equals to PcdMinimalYear / 100 or equals to PcdMinimalYear / 100 + 1.

The patch passed the Y2K test.
However with year range [1998, 2097], when system time is 2097/12/31 23:59:59,
the next second system time will become 1998/1/1 0:0:0. I think it's a acceptable limitation.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
Reviewed-by: Feng Tian <feng.tian@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17624 6f19259b-4bc3-4df7-8a09-765794883524

1 files changed, 22 insertions, 33 deletions

diff --git a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c
index 23f8d3b56f..9ec309c6b9 100644
--- a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c
+++ b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c
@@ -100,7 +100,6 @@ PcRtcInit (
   RTC_REGISTER_A  RegisterA;

   RTC_REGISTER_B  RegisterB;

   RTC_REGISTER_D  RegisterD;

-  UINT8           Century;

   EFI_TIME        Time;

   UINTN           DataSize;

   UINT32          TimerVar;

@@ -163,8 +162,6 @@ PcRtcInit (
   Time.Month  = RtcRead (RTC_ADDRESS_MONTH);

   Time.Year   = RtcRead (RTC_ADDRESS_YEAR);

 

-  Century = RtcRead (RTC_ADDRESS_CENTURY);

-  

   //

   // Set RTC configuration after get original time

   // The value of bit AIE should be reserved.

@@ -201,7 +198,7 @@ PcRtcInit (
   //

   // Validate time fields

   //

-  Status = ConvertRtcTimeToEfiTime (&Time, Century, RegisterB);

+  Status = ConvertRtcTimeToEfiTime (&Time, RegisterB);

   if (!EFI_ERROR (Status)) {

     Status = RtcTimeFieldsValid (&Time);

   }

@@ -218,7 +215,7 @@ PcRtcInit (
     Time.Hour   = RTC_INIT_HOUR;

     Time.Day    = RTC_INIT_DAY;

     Time.Month  = RTC_INIT_MONTH;

-    Time.Year   = RTC_INIT_YEAR;

+    Time.Year   = PcdGet16 (PcdMinimalValidYear);

     Time.Nanosecond  = 0;

     Time.TimeZone = EFI_UNSPECIFIED_TIMEZONE;

     Time.Daylight = 0;

@@ -251,7 +248,7 @@ PcRtcInit (
   Time.Hour   = RTC_INIT_HOUR;

   Time.Day    = RTC_INIT_DAY;

   Time.Month  = RTC_INIT_MONTH;

-  Time.Year   = RTC_INIT_YEAR;

+  Time.Year   = PcdGet16 (PcdMinimalValidYear);

   Time.Nanosecond  = 0;

   Time.TimeZone = Global->SavedTimeZone;

   Time.Daylight = Global->Daylight;;

@@ -272,8 +269,8 @@ PcRtcInit (
     }

     return EFI_DEVICE_ERROR;

   }

-  

-  ConvertEfiTimeToRtcTime (&Time, RegisterB, &Century);

+

+  ConvertEfiTimeToRtcTime (&Time, RegisterB);

 

   //

   // Set the Y/M/D info to variable as it has no corresponding hw registers.

@@ -343,7 +340,6 @@ PcRtcGetTime (
 {

   EFI_STATUS      Status;

   RTC_REGISTER_B  RegisterB;

-  UINT8           Century;

 

   //

   // Check parameters for null pointer

@@ -383,8 +379,6 @@ PcRtcGetTime (
   Time->Month   = RtcRead (RTC_ADDRESS_MONTH);

   Time->Year    = RtcRead (RTC_ADDRESS_YEAR);

 

-  Century = RtcRead (RTC_ADDRESS_CENTURY);

-  

   //

   // Release RTC Lock.

   //

@@ -401,7 +395,7 @@ PcRtcGetTime (
   //

   // Make sure all field values are in correct range

   //

-  Status = ConvertRtcTimeToEfiTime (Time, Century, RegisterB);

+  Status = ConvertRtcTimeToEfiTime (Time, RegisterB);

   if (!EFI_ERROR (Status)) {

     Status = RtcTimeFieldsValid (Time);

   }

@@ -447,7 +441,6 @@ PcRtcSetTime (
   EFI_STATUS      Status;

   EFI_TIME        RtcTime;

   RTC_REGISTER_B  RegisterB;

-  UINT8           Century;

   UINT32          TimerVar;

 

   if (Time == NULL) {

@@ -506,7 +499,7 @@ PcRtcSetTime (
   RegisterB.Bits.Set  = 1;

   RtcWrite (RTC_ADDRESS_REGISTER_B, RegisterB.Data);

 

-  ConvertEfiTimeToRtcTime (&RtcTime, RegisterB, &Century);

+  ConvertEfiTimeToRtcTime (&RtcTime, RegisterB);

 

   RtcWrite (RTC_ADDRESS_SECONDS, RtcTime.Second);

   RtcWrite (RTC_ADDRESS_MINUTES, RtcTime.Minute);

@@ -514,7 +507,6 @@ PcRtcSetTime (
   RtcWrite (RTC_ADDRESS_DAY_OF_THE_MONTH, RtcTime.Day);

   RtcWrite (RTC_ADDRESS_MONTH, RtcTime.Month);

   RtcWrite (RTC_ADDRESS_YEAR, (UINT8) RtcTime.Year);

-  RtcWrite (RTC_ADDRESS_CENTURY, Century);

 

   //

   // Allow updates of the RTC registers

@@ -564,7 +556,6 @@ PcRtcGetWakeupTime (
   EFI_STATUS      Status;

   RTC_REGISTER_B  RegisterB;

   RTC_REGISTER_C  RegisterC;

-  UINT8           Century;

   EFI_TIME        RtcTime;

   UINTN           DataSize;

 

@@ -612,8 +603,6 @@ PcRtcGetWakeupTime (
   Time->TimeZone = Global->SavedTimeZone;

   Time->Daylight = Global->Daylight;

 

-  Century = RtcRead (RTC_ADDRESS_CENTURY);

-

   //

   // Get the alarm info from variable

   //

@@ -644,7 +633,7 @@ PcRtcGetWakeupTime (
   //

   // Make sure all field values are in correct range

   //

-  Status = ConvertRtcTimeToEfiTime (Time, Century, RegisterB);

+  Status = ConvertRtcTimeToEfiTime (Time, RegisterB);

   if (!EFI_ERROR (Status)) {

     Status = RtcTimeFieldsValid (Time);

   }

@@ -680,7 +669,6 @@ PcRtcSetWakeupTime (
   EFI_STATUS            Status;

   EFI_TIME              RtcTime;

   RTC_REGISTER_B        RegisterB;

-  UINT8                 Century;

   EFI_TIME_CAPABILITIES Capabilities;

 

   ZeroMem (&RtcTime, sizeof (RtcTime));

@@ -736,7 +724,7 @@ PcRtcSetWakeupTime (
   RegisterB.Data = RtcRead (RTC_ADDRESS_REGISTER_B);

 

   if (Enable) {

-    ConvertEfiTimeToRtcTime (&RtcTime, RegisterB, &Century);

+    ConvertEfiTimeToRtcTime (&RtcTime, RegisterB);

   } else {

     //

     // if the alarm is disable, record the current setting.

@@ -837,7 +825,6 @@ CheckAndConvertBcd8ToDecimal8 (
 

   @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.

 

@@ -848,11 +835,11 @@ CheckAndConvertBcd8ToDecimal8 (
 EFI_STATUS

 ConvertRtcTimeToEfiTime (

   IN OUT EFI_TIME        *Time,

-  IN     UINT8           Century,

   IN     RTC_REGISTER_B  RegisterB

   )

 {

   BOOLEAN IsPM;

+  UINT8   Century;

 

   if ((Time->Hour & 0x80) != 0) {

     IsPM = TRUE;

@@ -870,14 +857,21 @@ ConvertRtcTimeToEfiTime (
     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) {

+      Time->Hour == 0xff || Time->Minute == 0xff || Time->Second == 0xff) {

     return EFI_INVALID_PARAMETER;

   }

 

+  //

+  // For minimal/maximum year range [1970, 2069],

+  //   Century is 19 if RTC year >= 70,

+  //   Century is 20 otherwise.

+  //

+  Century = (UINT8) (PcdGet16 (PcdMinimalValidYear) / 100);

+  if (Time->Year < PcdGet16 (PcdMinimalValidYear) % 100) {

+    Century++;

+  }

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

 

   //

@@ -1053,14 +1047,11 @@ IsLeapYear (
   @param   Time       On input, the time data read from UEFI to convert

                       On output, the time converted to RTC format

   @param   RegisterB  Value of Register B of RTC, indicating data mode

-  @param   Century    It is set according to EFI_TIME Time.

-

 **/

 VOID

 ConvertEfiTimeToRtcTime (

   IN OUT EFI_TIME        *Time,

-  IN     RTC_REGISTER_B  RegisterB,

-     OUT UINT8           *Century

+  IN     RTC_REGISTER_B  RegisterB

   )

 {

   BOOLEAN IsPM;

@@ -1081,10 +1072,8 @@ ConvertEfiTimeToRtcTime (
     }

   }

   //

-  // Set the Time/Date/Daylight Savings values.

+  // Set the Time/Date values.

   //

-  *Century    = DecimalToBcd8 ((UINT8) (Time->Year / 100));

-

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

 

   if (RegisterB.Bits.Dm == 0) {