[PATCH edk2-platforms 08/27] Silicon/NXP: Add Virtual RTC support for i.MX platform

[Chris Co <Christopher.Co@microsoft.com>]

This adds a virtual RTC library that implements EFI RTC runtime services
based on the ARM performance counter.  It should only be used for relative
time measurement, such as for Windows Boot Manager.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Christopher Co <christopher.co@microsoft.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
---
 Silicon/NXP/iMXPlatformPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c   | 227 ++++++++++++++++++++
 Silicon/NXP/iMXPlatformPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf |  37 ++++
 2 files changed, 264 insertions(+)

diff --git a/Silicon/NXP/iMXPlatformPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c b/Silicon/NXP/iMXPlatformPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c
new file mode 100644
index 000000000000..771c1d7a8f9c
--- /dev/null
+++ b/Silicon/NXP/iMXPlatformPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.c
@@ -0,0 +1,227 @@
+/** @file
+*
+*  Implement EFI RealTimeClock runtime services based on ARM Performance Counter.
+*
+*  Currently this driver does not support time setting, alarms, or runtime calls.
+*  This special library is NOT meant to replace a HW RTC implementation to
+*  measure date/time. Use this library ONLY to measure relative time between
+*  two EFI_GET_TIME readings.
+*  The performance counter will wrap-around eventually after a long time, make
+*  sure to consider this limitation if you are depending on this library for
+*  relative time measurement. e.g. For the ARM 64-bit counter with 19.2MHz
+*  frequency, the counter will wrap-around after approximately 30465 year.
+*
+*  Copyright (c) 2018 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.
+*
+**/
+
+#include <PiDxe.h>
+
+#include <Library/BaseLib.h>
+#include <Library/DebugLib.h>
+#include <Library/IoLib.h>
+#include <Library/RealTimeClockLib.h>
+#include <Library/TimerLib.h>
+
+#define LOG_FMT_HELPER(FMT, ...) \
+    "VirtualRealTimeClock:" FMT "%a\n", __VA_ARGS__
+
+#define LOG_TRACE(...) \
+    DEBUG((DEBUG_BLKIO, LOG_FMT_HELPER(__VA_ARGS__, "")))
+
+/**
+  Returns the current time and date information, and the time-keeping capabilities
+  of the virtual RTC.
+
+  For simplicity, this LibGetTime does not report Years/Months, instead it will
+  only report current Day, Hours, Minutes and Seconds starting from the beginning
+  of CPU up-time. Otherwise, a more complex logic will be required to account
+  for leap years and days/month differences.
+
+  @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
+  )
+{
+  UINT64 ElapsedSeconds;
+  UINT64 TimerFreq;
+
+  if (Time == NULL) {
+    return EFI_INVALID_PARAMETER;
+  }
+
+  // Depend on ARM ARCH Timer (i.e. performance counter) to report date/time
+  // relative to the start of CPU timer counting where date and time will always
+  // be relative to the date/time 1/1/1900 00H:00M:00S
+  if (PcdGet32 (PcdArmArchTimerFreqInHz) > 0) {
+    TimerFreq = PcdGet32 (PcdArmArchTimerFreqInHz);
+  } else {
+    TimerFreq = GetPerformanceCounterProperties (NULL, NULL);
+  }
+
+  ASSERT (TimerFreq > 0);
+  if (TimerFreq == 0) {
+    return EFI_DEVICE_ERROR;
+  }
+
+  if (Capabilities) {
+    Capabilities->Accuracy = 0;
+    Capabilities->Resolution = TimerFreq;
+    Capabilities->SetsToZero = FALSE;
+  }
+
+  ElapsedSeconds = GetPerformanceCounter () / TimerFreq;
+
+  // Don't report Year/Month since Leap Year logic is not implemented. This should
+  // be fine since the sole purpose of this special implementation is to be
+  // used for relative time measurement. e.g. Windows Boot Manager.
+  Time->Year = 0;
+  Time->Month = 0;
+
+  CONST UINT64 SECONDS_PER_DAY = 24 * 60 * 60;
+  Time->Day = (ElapsedSeconds / SECONDS_PER_DAY);
+  ElapsedSeconds %= SECONDS_PER_DAY;
+
+  CONST UINT64 SECONDS_PER_HOUR = 60 * 60;
+  Time->Hour = (ElapsedSeconds / SECONDS_PER_HOUR);
+  ElapsedSeconds %= SECONDS_PER_HOUR;
+
+  CONST UINT64 SECONDS_PER_MINUTE = 60;
+  Time->Minute = (ElapsedSeconds / SECONDS_PER_MINUTE);
+  ElapsedSeconds %= SECONDS_PER_MINUTE;
+
+  Time->Second = ElapsedSeconds;
+  Time->Nanosecond = 0;
+  Time->TimeZone = 0;
+  Time->Daylight = 0;
+
+  LOG_TRACE (
+    "Time Elapsed Since Power-On: Day%d %dh:%dm:%ds",
+    (UINT32)Time->Day,
+    (UINT32)Time->Hour,
+    (UINT32)Time->Minute,
+    (UINT32)Time->Second);
+
+  return EFI_SUCCESS;
+}
+
+/**
+  Sets the current local time and date information.
+
+  @param  Time                  A pointer to the current time.
+
+  @retval EFI_UNSUPPORTED      This operation is not supported.
+
+**/
+EFI_STATUS
+EFIAPI
+LibSetTime (
+  IN EFI_TIME *Time
+  )
+{
+  // The virtual clock is read-only.
+  return EFI_UNSUPPORTED;
+}
+
+/**
+  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_UNSUPPORTED       A wakeup timer is not supported on this platform.
+
+**/
+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_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
+  )
+{
+  // ARM ARCH Timer is already initialized in the SEC/PEI phase.
+  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
+  )
+{
+  // Not supporting OS calling RTC functions in virtual mode.
+  return;
+}
diff --git a/Silicon/NXP/iMXPlatformPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf b/Silicon/NXP/iMXPlatformPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
new file mode 100644
index 000000000000..54aacde8c741
--- /dev/null
+++ b/Silicon/NXP/iMXPlatformPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
@@ -0,0 +1,37 @@
+## @file
+#
+#  Copyright (c) 2018 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]
+  ArmPkg/ArmPkg.dec
+  EmbeddedPkg/EmbeddedPkg.dec
+  MdePkg/MdePkg.dec
+
+[LibraryClasses]
+  DebugLib
+  IoLib
+  TimerLib
+
+[FixedPcd]
+  gArmTokenSpaceGuid.PcdArmArchTimerFreqInHz
-- 
2.16.2.gvfs.1.33.gf5370f1