OvmfPkg/Library/XenRealTimeClockLib/XenRealTimeClockLib.c

   1 /** @file
   2   Implement EFI RealTimeClock runtime services via Xen shared info page
   3
   4   Copyright (c) 2015, Linaro Ltd. All rights reserved.<BR>
   5
   6   SPDX-License-Identifier: BSD-2-Clause-Patent
   7
   8 **/
   9
  10 #include <Uefi.h>
  11 #include <PiDxe.h>
  12 #include <Library/BaseLib.h>
  13 #include <Library/DebugLib.h>
  14
  15 /**
  16   Converts Epoch seconds (elapsed since 1970 JANUARY 01, 00:00:00 UTC) to EFI_TIME
  17  **/
  18 STATIC
  19 VOID
  20 EpochToEfiTime (
  21   IN  UINTN     EpochSeconds,
  22   OUT EFI_TIME  *Time
  23   )
  24 {
  25   UINTN  a;
  26   UINTN  b;
  27   UINTN  c;
  28   UINTN  d;
  29   UINTN  g;
  30   UINTN  j;
  31   UINTN  m;
  32   UINTN  y;
  33   UINTN  da;
  34   UINTN  db;
  35   UINTN  dc;
  36   UINTN  dg;
  37   UINTN  hh;
  38   UINTN  mm;
  39   UINTN  ss;
  40   UINTN  J;
  41
  42   J  = (EpochSeconds / 86400) + 2440588;
  43   j  = J + 32044;
  44   g  = j / 146097;
  45   dg = j % 146097;
  46   c  = (((dg / 36524) + 1) * 3) / 4;
  47   dc = dg - (c * 36524);
  48   b  = dc / 1461;
  49   db = dc % 1461;
  50   a  = (((db / 365) + 1) * 3) / 4;
  51   da = db - (a * 365);
  52   y  = (g * 400) + (c * 100) + (b * 4) + a;
  53   m  = (((da * 5) + 308) / 153) - 2;
  54   d  = da - (((m + 4) * 153) / 5) + 122;
  55
  56   Time->Year  = (UINT16)(y - 4800 + ((m + 2) / 12));
  57   Time->Month = ((m + 2) % 12) + 1;
  58   Time->Day   = (UINT8)(d + 1);
  59
  60   ss = EpochSeconds % 60;
  61   a  = (EpochSeconds - ss) / 60;
  62   mm = a % 60;
  63   b  = (a - mm) / 60;
  64   hh = b % 24;
  65
  66   Time->Hour       = (UINT8)hh;
  67   Time->Minute     = (UINT8)mm;
  68   Time->Second     = (UINT8)ss;
  69   Time->Nanosecond = 0;
  70 }
  71
  72 /**
  73   Returns the current time and date information, and the time-keeping capabilities
  74   of the hardware platform.
  75
  76   @param  Time                  A pointer to storage to receive a snapshot of the current time.
  77   @param  Capabilities          An optional pointer to a buffer to receive the real time clock
  78                                 device's capabilities.
  79
  80   @retval EFI_SUCCESS           The operation completed successfully.
  81   @retval EFI_INVALID_PARAMETER Time is NULL.
  82   @retval EFI_DEVICE_ERROR      The time could not be retrieved due to hardware error.
  83
  84 **/
  85 EFI_STATUS
  86 EFIAPI
  87 LibGetTime (
  88   OUT EFI_TIME                *Time,
  89   OUT  EFI_TIME_CAPABILITIES  *Capabilities
  90   )
  91 {
  92   ASSERT (Time != NULL);
  93
  94   //
  95   // For now, there is nothing that we can do besides returning a bogus time,
  96   // as Xen's timekeeping uses a shared info page which cannot be shared
  97   // between UEFI and the OS
  98   //
  99   EpochToEfiTime (1421770011, Time);
 100
 101   return EFI_SUCCESS;
 102 }
 103
 104 /**
 105   Sets the current local time and date information.
 106
 107   @param  Time                  A pointer to the current time.
 108
 109   @retval EFI_SUCCESS           The operation completed successfully.
 110   @retval EFI_INVALID_PARAMETER A time field is out of range.
 111   @retval EFI_DEVICE_ERROR      The time could not be set due due to hardware error.
 112
 113 **/
 114 EFI_STATUS
 115 EFIAPI
 116 LibSetTime (
 117   IN EFI_TIME  *Time
 118   )
 119 {
 120   return EFI_DEVICE_ERROR;
 121 }
 122
 123 /**
 124   Returns the current wakeup alarm clock setting.
 125
 126   @param  Enabled               Indicates if the alarm is currently enabled or disabled.
 127   @param  Pending               Indicates if the alarm signal is pending and requires acknowledgement.
 128   @param  Time                  The current alarm setting.
 129
 130   @retval EFI_SUCCESS           The alarm settings were returned.
 131   @retval EFI_INVALID_PARAMETER Any parameter is NULL.
 132   @retval EFI_DEVICE_ERROR      The wakeup time could not be retrieved due to a hardware error.
 133   @retval EFI_UNSUPPORTED       A wakeup timer is not supported on this platform.
 134
 135 **/
 136 EFI_STATUS
 137 EFIAPI
 138 LibGetWakeupTime (
 139   OUT BOOLEAN   *Enabled,
 140   OUT BOOLEAN   *Pending,
 141   OUT EFI_TIME  *Time
 142   )
 143 {
 144   return EFI_UNSUPPORTED;
 145 }
 146
 147 /**
 148   Sets the system wakeup alarm clock time.
 149
 150   @param  Enabled               Enable or disable the wakeup alarm.
 151   @param  Time                  If Enable is TRUE, the time to set the wakeup alarm for.
 152
 153   @retval EFI_SUCCESS           If Enable is TRUE, then the wakeup alarm was enabled. If
 154                                 Enable is FALSE, then the wakeup alarm was disabled.
 155   @retval EFI_INVALID_PARAMETER A time field is out of range.
 156   @retval EFI_DEVICE_ERROR      The wakeup time could not be set due to a hardware error.
 157   @retval EFI_UNSUPPORTED       A wakeup timer is not supported on this platform.
 158
 159 **/
 160 EFI_STATUS
 161 EFIAPI
 162 LibSetWakeupTime (
 163   IN BOOLEAN    Enabled,
 164   OUT EFI_TIME  *Time
 165   )
 166 {
 167   return EFI_UNSUPPORTED;
 168 }
 169
 170 /**
 171   This is the declaration of an EFI image entry point. This can be the entry point to an application
 172   written to this specification, an EFI boot service driver, or an EFI runtime driver.
 173
 174   @param  ImageHandle           Handle that identifies the loaded image.
 175   @param  SystemTable           System Table for this image.
 176
 177   @retval EFI_SUCCESS           The operation completed successfully.
 178
 179 **/
 180 EFI_STATUS
 181 EFIAPI
 182 LibRtcInitialize (
 183   IN EFI_HANDLE        ImageHandle,
 184   IN EFI_SYSTEM_TABLE  *SystemTable
 185   )
 186 {
 187   return EFI_SUCCESS;
 188 }