[PATCH 1/1] EmbeddedPkg/Library: Add VirtualRealTimeClockLib

[Pete Batard <pete@akeo.ie>]

This is designed to be used on platforms where a a real RTC is not
available and relies on an RtcEpochSeconds variable having been set or,
if that is not the case, falls back to using the epoch embedded at
compilation time.

Note that, in order to keep things simple for the setting of the
compilation time variable, only GCC environments with UNIX-like shells
and where a 'date' command is available are meant to be supported for
now.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Pete Batard <pete@akeo.ie>
---
 EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c   | 400 ++++++++++++++++++++
 EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf |  43 +++
 2 files changed, 443 insertions(+)

diff --git a/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c
new file mode 100644
index 000000000000..4c354730d02b
--- /dev/null
+++ b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c
@@ -0,0 +1,400 @@
+/** @file
+ *
+ *  Implement virtual EFI RealTimeClock runtime services.
+ *
+ *  Coypright (c) 2019, Pete Batard <pete@akeo.ie>
+ *  Copyright (c) 2018, Andrei Warkentin <andrey.warkentin@gmail.com>
+ *  Copyright (c) 2011-2014, ARM Ltd. All rights reserved.
+ *  Copyright (c) 2008-2010, Apple Inc. All rights reserved.
+ *  Copyright (c) Microsoft 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.
+ *
+ *  Based on ArmPlatformPkg/Library/PL031RealTimeClockLib/PL031RealTimeClockLib.inf
+ *
+ **/
+
+#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";
+
+/**
+   Returns the current time and date information, and the time-keeping capabilities
+   of the virtual RTC.
+
+   @param  Time                  A pointer to storage to receive a snapshot of the current time.
+   @param  Capabilities          An optional pointer to a buffer to receive the real time clock
+                                 device's capabilities.
+
+   @retval EFI_SUCCESS           The operation completed successfully.
+   @retval EFI_INVALID_PARAMETER Time is NULL.
+   @retval EFI_DEVICE_ERROR      The time could not be retrieved due to hardware error.
+
+**/
+EFI_STATUS
+EFIAPI
+LibGetTime (
+  OUT EFI_TIME               *Time,
+  OUT EFI_TIME_CAPABILITIES  *Capabilities
+  )
+{
+  EFI_STATUS  Status;
+  UINT32      EpochSeconds;
+  INT16       TimeZone;
+  UINT8       Daylight;
+  UINT64      Freq;
+  UINT64      Counter;
+  UINT64      Remainder;
+  UINTN       ElapsedSeconds;
+  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);
+  ElapsedSeconds = 0;
+  Status = EfiGetVariable (
+             (CHAR16 *)mEpochVariableName,
+             &gEfiCallerIdGuid,
+             NULL,
+             &Size,
+             (VOID *)&ElapsedSeconds
+             );
+  // 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.
+    //
+    ElapsedSeconds = BUILD_EPOCH;
+    DEBUG ((
+      DEBUG_INFO,
+      "LibGetTime: %s non volatile variable was not found - Using compilation time epoch.\n",
+      mEpochVariableName
+      ));
+  }
+  Counter = GetPerformanceCounter ();
+  ElapsedSeconds += 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 (ElapsedSeconds, 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 = MultU64x64 (Remainder, 1000000000U) / Freq;
+  } else {
+    DEBUG ((DEBUG_WARN, "LibGetTime: Nanosecond value not set (64-bit overflow).\n"));
+  }
+
+  if (Capabilities) {
+    Capabilities->Accuracy   = 0;
+    Capabilities->Resolution = Freq;
+    Capabilities->SetsToZero = FALSE;
+  }
+
+  return EFI_SUCCESS;
+}
+
+/**
+   Sets the current local time and date information.
+
+   @param  Time                  A pointer to the current time.
+
+   @retval EFI_SUCCESS           The operation completed successfully.
+   @retval EFI_INVALID_PARAMETER A time field is out of range.
+   @retval EFI_DEVICE_ERROR      The time could not be set due due to hardware error.
+
+**/
+EFI_STATUS
+EFIAPI
+LibSetTime (
+  IN EFI_TIME  *Time
+  )
+{
+  EFI_STATUS  Status;
+  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;
+  }
+
+  // Adjust for the correct period
+  if ((Time->Daylight & EFI_TIME_IN_DAYLIGHT) == EFI_TIME_IN_DAYLIGHT) {
+    // Convert to un-adjusted time, i.e. fall back one hour
+    EpochSeconds -= SEC_PER_HOUR;
+  }
+
+  // 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",
+      mDaylightVariableName,
+      Status
+      ));
+    return Status;
+  }
+
+  return EFI_SUCCESS;
+}
+
+/**
+   Returns the current wakeup alarm clock setting.
+
+   @param  Enabled               Indicates if the alarm is currently enabled or disabled.
+   @param  Pending               Indicates if the alarm signal is pending and requires acknowledgement.
+   @param  Time                  The current alarm setting.
+
+   @retval EFI_SUCCESS           The alarm settings were returned.
+   @retval EFI_INVALID_PARAMETER Any parameter is NULL.
+   @retval EFI_DEVICE_ERROR      The wakeup time could not be retrieved due to a hardware error.
+
+**/
+EFI_STATUS
+EFIAPI
+LibGetWakeupTime (
+  OUT BOOLEAN   *Enabled,
+  OUT BOOLEAN   *Pending,
+  OUT EFI_TIME  *Time
+  )
+{
+  return EFI_UNSUPPORTED;
+}
+
+/**
+   Sets the system wakeup alarm clock time.
+
+   @param  Enabled               Enable or disable the wakeup alarm.
+   @param  Time                  If Enable is TRUE, the time to set the wakeup alarm for.
+
+   @retval EFI_SUCCESS           If Enable is TRUE, then the wakeup alarm was enabled. If
+   Enable is FALSE, then the wakeup alarm was disabled.
+   @retval EFI_INVALID_PARAMETER A time field is out of range.
+   @retval EFI_DEVICE_ERROR      The wakeup time could not be set due to a hardware error.
+   @retval EFI_UNSUPPORTED       A wakeup timer is not supported on this platform.
+
+**/
+EFI_STATUS
+EFIAPI
+LibSetWakeupTime (
+  IN  BOOLEAN   Enabled,
+  OUT EFI_TIME  *Time
+  )
+{
+  return EFI_UNSUPPORTED;
+}
+
+/**
+   This is the declaration of an EFI image entry point. This can be the entry point to an application
+   written to this specification, an EFI boot service driver, or an EFI runtime driver.
+
+   @param  ImageHandle           Handle that identifies the loaded image.
+   @param  SystemTable           System Table for this image.
+
+   @retval EFI_SUCCESS           The operation completed successfully.
+
+**/
+EFI_STATUS
+EFIAPI
+LibRtcInitialize (
+  IN EFI_HANDLE        ImageHandle,
+  IN EFI_SYSTEM_TABLE  *SystemTable
+  )
+{
+  return EFI_SUCCESS;
+}
+
+/**
+   Fixup internal data so that EFI can be call in virtual mode.
+   Call the passed in Child Notify event and convert any pointers in
+   lib to virtual mode.
+
+   @param[in]    Event   The Event that is being processed
+   @param[in]    Context Event Context
+**/
+VOID
+EFIAPI
+LibRtcVirtualNotifyEvent (
+  IN EFI_EVENT  Event,
+  IN VOID       *Context
+  )
+{
+  return;
+}
diff --git a/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
new file mode 100644
index 000000000000..ed69faad4205
--- /dev/null
+++ b/EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
@@ -0,0 +1,43 @@
+#/** @file
+#
+#  Implement virtual EFI RealTimeClock runtime services.
+#
+#  Copyright (c) 2019, Pete Batard <pete@akeo.ie>
+#  Copyright (c) 2018, Andrei Warkentin <andrey.warkentin@gmail.com>
+#  Copyright (c) Microsoft 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.
+#
+#**/
+
+[Defines]
+  INF_VERSION                    = 0x0001001A
+  BASE_NAME                      = VirtualRealTimeClockLib
+  FILE_GUID                      = 1E27D461-78F3-4F7D-B1C2-F72384F13A6E
+  MODULE_TYPE                    = BASE
+  VERSION_STRING                 = 1.0
+  LIBRARY_CLASS                  = RealTimeClockLib
+
+[Sources.common]
+  VirtualRealTimeClockLib.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+  EmbeddedPkg/EmbeddedPkg.dec
+
+[LibraryClasses]
+  IoLib
+  DebugLib
+  TimerLib
+  TimeBaseLib
+  UefiRuntimeLib
+
+# Current usage of this library expects GCC in a UNIX-like shell environment with the date command
+[BuildOptions]
+  GCC:*_*_*_CC_FLAGS = -DBUILD_EPOCH=`date +%s`
-- 
2.17.0.windows.1