Re: [edk2-platforms][PATCH v2 07/32] JadePkg: Implement RealTimeClockLib for PCF85063

["Leif Lindholm" <leif@nuviainc.com>]

On Wed, May 26, 2021 at 17:06:59 +0700, Nhi Pham wrote:
> From: Vu Nguyen <vunguyen@os.amperecomputing.com>
> 
> This library adds the support for retrieving and updating system
> datetime over real RTC PCF85063 device on Mt. Jade platform instead of
> using virtual RTC.
> 
> Cc: Thang Nguyen <thang@os.amperecomputing.com>
> Cc: Chuong Tran <chuong@os.amperecomputing.com>
> Cc: Phong Vo <phong@os.amperecomputing.com>
> Cc: Leif Lindholm <leif@nuviainc.com>
> Cc: Michael D Kinney <michael.d.kinney@intel.com>
> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
> Cc: Nate DeSimone <nathaniel.l.desimone@intel.com>
> 
> Signed-off-by: Vu Nguyen <vunguyen@os.amperecomputing.com>
> ---
>  Silicon/Ampere/AmpereAltraPkg/AmpereAltraPkg.dsc.inc                                  |   2 +
>  Platform/Ampere/JadePkg/Jade.dsc                                                      |   2 +-
>  Platform/Ampere/JadePkg/Library/PCF85063RealTimeClockLib/PCF85063RealTimeClockLib.inf |  44 +++
>  Platform/Ampere/JadePkg/Library/PCF85063RealTimeClockLib/PCF85063.h                   |  91 ++++++
>  Platform/Ampere/JadePkg/Library/PCF85063RealTimeClockLib/PCF85063.c                   | 317 ++++++++++++++++++++
>  Platform/Ampere/JadePkg/Library/PCF85063RealTimeClockLib/PCF85063RealTimeClockLib.c   | 257 ++++++++++++++++
>  6 files changed, 712 insertions(+), 1 deletion(-)
> 
> diff --git a/Silicon/Ampere/AmpereAltraPkg/AmpereAltraPkg.dsc.inc b/Silicon/Ampere/AmpereAltraPkg/AmpereAltraPkg.dsc.inc
> index 6a6f72e995af..9f19f495fad2 100755
> --- a/Silicon/Ampere/AmpereAltraPkg/AmpereAltraPkg.dsc.inc
> +++ b/Silicon/Ampere/AmpereAltraPkg/AmpereAltraPkg.dsc.inc
> @@ -84,6 +84,8 @@ [LibraryClasses.common]
>    SystemFirmwareInterfaceLib|Silicon/Ampere/AmpereAltraPkg/Library/SystemFirmwareInterfaceLib/SystemFirmwareInterfaceLib.inf
>    AmpereCpuLib|Silicon/Ampere/AmpereAltraPkg/Library/AmpereCpuLib/AmpereCpuLib.inf
>    TimeBaseLib|EmbeddedPkg/Library/TimeBaseLib/TimeBaseLib.inf
> +  I2cLib|Silicon/Ampere/AmpereAltraPkg/Library/DwI2cLib/DwI2cLib.inf
> +  GpioLib|Silicon/Ampere/AmpereAltraPkg/Library/DwGpioLib/DwGpioLib.inf
>    MmCommunicationLib|Silicon/Ampere/AmpereAltraPkg/Library/MmCommunicationLib/MmCommunicationLib.inf
>  
>    #
> diff --git a/Platform/Ampere/JadePkg/Jade.dsc b/Platform/Ampere/JadePkg/Jade.dsc
> index f92855af99ab..f37ab1a92e44 100755
> --- a/Platform/Ampere/JadePkg/Jade.dsc
> +++ b/Platform/Ampere/JadePkg/Jade.dsc
> @@ -73,7 +73,7 @@ [LibraryClasses]
>    #
>    # RTC Library: Common RTC
>    #
> -  RealTimeClockLib|EmbeddedPkg/Library/VirtualRealTimeClockLib/VirtualRealTimeClockLib.inf
> +  RealTimeClockLib|Platform/Ampere/JadePkg/Library/PCF85063RealTimeClockLib/PCF85063RealTimeClockLib.inf
>  
>    #
>    # Library for FailSafe support
> diff --git a/Platform/Ampere/JadePkg/Library/PCF85063RealTimeClockLib/PCF85063RealTimeClockLib.inf b/Platform/Ampere/JadePkg/Library/PCF85063RealTimeClockLib/PCF85063RealTimeClockLib.inf
> new file mode 100644
> index 000000000000..1fe561cc0ec9
> --- /dev/null
> +++ b/Platform/Ampere/JadePkg/Library/PCF85063RealTimeClockLib/PCF85063RealTimeClockLib.inf
> @@ -0,0 +1,44 @@
> +## @file
> +#
> +# Copyright (c) 2020 - 2021, Ampere Computing LLC. All rights reserved.<BR>
> +#
> +# SPDX-License-Identifier: BSD-2-Clause-Patent
> +#
> +##
> +
> +[Defines]
> +  INF_VERSION                      = 0x0001001B
> +  MODULE_TYPE                      = BASE
> +  BASE_NAME                        = PCF85063RealTimeClockLib
> +  FILE_GUID                        = 271569F6-5522-4006-9FF5-F07A59473AAC
> +  LIBRARY_CLASS                    = RealTimeClockLib
> +  VERSION_STRING                   = 1.0
> +
> +[Sources.common]
> +  PCF85063.c
> +  PCF85063.h
> +  PCF85063RealTimeClockLib.c
> +
> +[Packages]
> +  ArmPkg/ArmPkg.dec
> +  ArmPlatformPkg/ArmPlatformPkg.dec
> +  EmbeddedPkg/EmbeddedPkg.dec
> +  MdePkg/MdePkg.dec
> +  Silicon/Ampere/AmpereAltraPkg/AmpereAltraPkg.dec
> +  Silicon/Ampere/AmpereSiliconPkg/AmpereSiliconPkg.dec
> +
> +[LibraryClasses]
> +  ArmGenericTimerCounterLib
> +  ArmLib
> +  BaseLib
> +  DebugLib
> +  GpioLib
> +  DxeServicesTableLib
> +  I2cLib
> +  TimeBaseLib
> +  TimerLib
> +  UefiLib
> +  UefiRuntimeLib
> +
> +[Guids]
> +  gEfiEventVirtualAddressChangeGuid
> diff --git a/Platform/Ampere/JadePkg/Library/PCF85063RealTimeClockLib/PCF85063.h b/Platform/Ampere/JadePkg/Library/PCF85063RealTimeClockLib/PCF85063.h
> new file mode 100644
> index 000000000000..03ce4d29a03f
> --- /dev/null
> +++ b/Platform/Ampere/JadePkg/Library/PCF85063RealTimeClockLib/PCF85063.h
> @@ -0,0 +1,91 @@
> +/** @file
> +
> +  Copyright (c) 2020 - 2021, Ampere Computing LLC. All rights reserved.<BR>
> +
> +  SPDX-License-Identifier: BSD-2-Clause-Patent
> +
> +**/
> +
> +#ifndef PCF85063_H_
> +#define PCF85063_H_
> +
> +#include <Uefi.h>
> +
> +#include <Library/BaseLib.h>
> +#include <Library/RealTimeClockLib.h>
> +
> +//
> +// I2C bus address that RTC connected to
> +//
> +#define I2C_RTC_BUS_ADDRESS        1
> +
> +//
> +// I2C RTC bus speed
> +//
> +#define I2C_RTC_BUS_SPEED          100000
> +
> +//
> +// I2C chip address that RTC connected to
> +//
> +#define I2C_RTC_CHIP_ADDRESS       0x51
> +
> +//
> +// The GPI PIN that tell if RTC can be access
> +//
> +#define I2C_RTC_ACCESS_GPIO_PIN    28
> +
> +/**
> + * Returns the current time and date information of the hardware platform.
> + *
> + * @param  Time                  A pointer to storage to receive a snapshot of the current time.
> + *
> + *
> + * @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
> +PlatformGetTime (
> +  OUT EFI_TIME *Time
> +  );
> +
> +/**
> + * Set the time and date information to the hardware platform.
> + *
> + * @param  Time                  A pointer to storage to set the current time to hardware platform.
> + *
> + *
> + * @retval EFI_SUCCESS           The operation completed successfully.
> + * @retval EFI_INVALID_PARAMETER Time is NULL.
> + * @retval EFI_DEVICE_ERROR      The time could not be set due due to hardware error.
> + **/
> +EFI_STATUS
> +EFIAPI
> +PlatformSetTime (
> +  IN EFI_TIME *Time
> +  );
> +
> +/**
> + * Callback function for hardware platform to convert data pointers to virtual address
> + */
> +VOID
> +EFIAPI
> +PlatformVirtualAddressChangeEvent (
> +  VOID
> +  );
> +
> +/**
> + * Callback function for hardware platform to initialize private data
> + *
> + *
> + * @retval EFI_SUCCESS           The operation completed successfully.
> + * @retval Others                The error status indicates the error
> + */
> +EFI_STATUS
> +EFIAPI
> +PlatformInitialize (
> +  VOID
> +  );
> +
> +#endif /* PCF85063_H_ */
> diff --git a/Platform/Ampere/JadePkg/Library/PCF85063RealTimeClockLib/PCF85063.c b/Platform/Ampere/JadePkg/Library/PCF85063RealTimeClockLib/PCF85063.c
> new file mode 100644
> index 000000000000..f9fa125d9d7e
> --- /dev/null
> +++ b/Platform/Ampere/JadePkg/Library/PCF85063RealTimeClockLib/PCF85063.c
> @@ -0,0 +1,317 @@
> +/** @file
> +
> +  Copyright (c) 2020 - 2021, Ampere Computing LLC. All rights reserved.<BR>
> +
> +  SPDX-License-Identifier: BSD-2-Clause-Patent
> +
> +**/
> +
> +#include <Uefi.h>
> +
> +#include <Library/BaseLib.h>
> +#include <Library/BaseMemoryLib.h>
> +#include <Library/DebugLib.h>
> +#include <Library/GpioLib.h>
> +#include <Library/I2cLib.h>
> +#include <Library/MemoryAllocationLib.h>
> +#include <Library/PcdLib.h>
> +#include <Library/TimerLib.h>
> +#include <Library/UefiBootServicesTableLib.h>
> +#include <Library/UefiLib.h>
> +#include <Library/UefiRuntimeLib.h>
> +#include <Library/UefiRuntimeServicesTableLib.h>
> +
> +#include "PCF85063.h"
> +
> +#define RTC_TIMEOUT_WAIT_ACCESS        100000 /* 100 miliseconds */
> +#define RTC_DEFAULT_MIN_YEAR           2000
> +#define RTC_DEFAULT_MAX_YEAR           2099
> +
> +#define RTC_ADDR                       0x4
> +#define RTC_DATA_BUF_LEN               8
> +
> +/**
> + * PCF85063 register offsets
> + */
> +#define PCF85063_OFFSET_SEC            0x0
> +#define PCF85063_OFFSET_MIN            0x1
> +#define PCF85063_OFFSET_HR             0x2
> +#define PCF85063_OFFSET_DAY            0x3
> +#define PCF85063_OFFSET_WKD            0x4
> +#define PCF85063_OFFSET_MON            0x5
> +#define PCF85063_OFFSET_YEA            0x6
> +
> +/**
> + * PCF85063 encoding macros
> + */
> +#define PCF85063_SEC_ENC(s) (((((s) / 10) & 0x7) << 4) | (((s) % 10) & 0xf))
> +#define PCF85063_MIN_ENC(m) (((((m) / 10) & 0x7) << 4) | (((m) % 10) & 0xf))
> +#define PCF85063_HR_ENC(h)  (((((h) / 10) & 0x3) << 4) | (((h) % 10) & 0xf))
> +#define PCF85063_DAY_ENC(d) (((((d) / 10) & 0x3) << 4) | (((d) % 10) & 0xf))
> +#define PCF85063_WKD_ENC(w) ((w) & 0x7)
> +#define PCF85063_MON_ENC(m) (((((m) / 10) & 0x1) << 4) | (((m) % 10) & 0xf))
> +#define PCF85063_YEA_ENC(y) (((((y) / 10) & 0xf) << 4) | (((y) % 10) & 0xf))
> +
> +/**
> + * PCF85063 decoding macros
> + */
> +#define PCF85063_SEC_DEC(s) (((((s) & 0x70) >> 4) * 10) + ((s) & 0xf))
> +#define PCF85063_MIN_DEC(m) (((((m) & 0x70) >> 4) * 10) + ((m) & 0xf))
> +#define PCF85063_HR_DEC(h)  (((((h) & 0x30) >> 4) * 10) + ((h) & 0xf))
> +#define PCF85063_DAY_DEC(d) (((((d) & 0x30) >> 4)* 10) + ((d) & 0xf))

*twitch*
Please add that space before '*' like on all other lines.

With that:
Reviewed-by: Leif Lindholm <leif@nuviainc.com>

/
    Leif

> +#define PCF85063_WKD_DEC(w) ((w) & 0x7)
> +#define PCF85063_MON_DEC(m) (((((m) & 0x10) >> 4) * 10) + ((m) & 0xf))
> +#define PCF85063_YEA_DEC(y) (((((y) & 0xf0) >> 4) * 10) + ((y) & 0xf))
> +
> +/* Buffer pointers to convert Vir2Phys and Phy2Vir */
> +STATIC volatile UINT64 RtcBufVir;
> +STATIC volatile UINT64 RtcBufPhy;
> +
> +STATIC
> +EFI_STATUS
> +RtcI2cWaitAccess (
> +  VOID
> +  )
> +{
> +  INTN Timeout;
> +
> +  Timeout = RTC_TIMEOUT_WAIT_ACCESS;
> +  while ((GpioReadBit (I2C_RTC_ACCESS_GPIO_PIN) != 0) && (Timeout > 0)) {
> +    MicroSecondDelay (100);
> +    Timeout -= 100;
> +  }
> +
> +  if (Timeout <= 0) {
> +    DEBUG ((DEBUG_ERROR, "%a: Timeout while waiting access RTC\n", __FUNCTION__));
> +    return EFI_TIMEOUT;
> +  }
> +
> +  return EFI_SUCCESS;
> +}
> +
> +STATIC
> +EFI_STATUS
> +RtcI2cRead (
> +  IN     UINT8  Addr,
> +  IN OUT UINT64 Data,
> +  IN     UINT32 DataLen
> +  )
> +{
> +  EFI_STATUS Status;
> +  UINT32     TmpLen;
> +
> +  if (EFI_ERROR (RtcI2cWaitAccess ())) {
> +    return EFI_DEVICE_ERROR;
> +  }
> +
> +  Status = I2cProbe (I2C_RTC_BUS_ADDRESS, I2C_RTC_BUS_SPEED);
> +  if (EFI_ERROR (Status)) {
> +    return EFI_DEVICE_ERROR;
> +  }
> +
> +  //
> +  // Send the slave address for read
> +  //
> +  TmpLen = 1;
> +  Status = I2cWrite (I2C_RTC_BUS_ADDRESS, I2C_RTC_CHIP_ADDRESS, (UINT8 *)&Addr, &TmpLen);
> +  if (EFI_ERROR (Status)) {
> +    return EFI_DEVICE_ERROR;
> +  }
> +
> +  //
> +  // Read back the time
> +  //
> +  Status = I2cRead (I2C_RTC_BUS_ADDRESS, I2C_RTC_CHIP_ADDRESS, NULL, 0, (UINT8 *)Data, &DataLen);
> +  if (EFI_ERROR (Status)) {
> +    return EFI_DEVICE_ERROR;
> +  }
> +
> +  return EFI_SUCCESS;
> +}
> +
> +EFI_STATUS
> +RtcI2cWrite (
> +  IN UINT8  Addr,
> +  IN UINT64 Data,
> +  IN UINT32 DataLen
> +  )
> +{
> +  EFI_STATUS Status;
> +  UINT8      TmpBuf[RTC_DATA_BUF_LEN + 1];
> +  UINT32     TmpLen;
> +
> +  if (EFI_ERROR (RtcI2cWaitAccess ())) {
> +    return EFI_DEVICE_ERROR;
> +  }
> +
> +  if (DataLen > sizeof (TmpBuf) - 1) {
> +    return EFI_INVALID_PARAMETER;
> +  }
> +
> +  Status = I2cProbe (I2C_RTC_BUS_ADDRESS, I2C_RTC_BUS_SPEED);
> +  if (EFI_ERROR (Status)) {
> +    return EFI_DEVICE_ERROR;
> +  }
> +
> +  //
> +  // The first byte is the address
> +  //
> +  TmpBuf[0] = Addr;
> +  TmpLen = DataLen + 1;
> +  CopyMem ((VOID *)(TmpBuf + 1), (VOID *)Data, DataLen);
> +
> +  Status = I2cWrite (I2C_RTC_BUS_ADDRESS, I2C_RTC_CHIP_ADDRESS, TmpBuf, &TmpLen);
> +  if (EFI_ERROR (Status)) {
> +    return EFI_DEVICE_ERROR;
> +  }
> +
> +  return EFI_SUCCESS;
> +}
> +
> +/**
> + * Returns the current time and date information of the hardware platform.
> + *
> + * @param  Time                  A pointer to storage to receive a snapshot of the current time.
> + *
> + *
> + * @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
> +PlatformGetTime (
> +  OUT EFI_TIME *Time
> +  )
> +{
> +  EFI_STATUS Status;
> +  UINT8      *Data;
> +
> +  if (Time == NULL) {
> +    return EFI_INVALID_PARAMETER;
> +  }
> +
> +  Status = RtcI2cRead (RTC_ADDR, RtcBufVir, RTC_DATA_BUF_LEN);
> +
> +  Data = (UINT8 *)RtcBufVir;
> +  if (Status == EFI_SUCCESS) {
> +    Time->Second = PCF85063_SEC_DEC (Data[PCF85063_OFFSET_SEC]);
> +    Time->Minute = PCF85063_MIN_DEC (Data[PCF85063_OFFSET_MIN]);
> +    Time->Hour   = PCF85063_HR_DEC (Data[PCF85063_OFFSET_HR]);
> +    Time->Day    = PCF85063_DAY_DEC (Data[PCF85063_OFFSET_DAY]);
> +    Time->Month  = PCF85063_MON_DEC (Data[PCF85063_OFFSET_MON]);
> +    Time->Year   = PCF85063_YEA_DEC (Data[PCF85063_OFFSET_YEA]);
> +    Time->Year  += RTC_DEFAULT_MIN_YEAR;
> +    if (Time->Year > RTC_DEFAULT_MAX_YEAR) {
> +      Time->Year = RTC_DEFAULT_MAX_YEAR;
> +    }
> +    if (Time->Year < RTC_DEFAULT_MIN_YEAR) {
> +      Time->Year = RTC_DEFAULT_MIN_YEAR;
> +    }
> +  }
> +
> +  return Status;
> +}
> +
> +/**
> + * Set the time and date information to the hardware platform.
> + *
> + * @param  Time                  A pointer to storage to set the current time to hardware platform.
> + *
> + *
> + * @retval EFI_SUCCESS           The operation completed successfully.
> + * @retval EFI_INVALID_PARAMETER Time is NULL.
> + * @retval EFI_DEVICE_ERROR      The time could not be set due due to hardware error.
> + **/
> +EFI_STATUS
> +EFIAPI
> +PlatformSetTime (
> +  IN EFI_TIME *Time
> +  )
> +{
> +  UINT8 *Data;
> +
> +  if (Time == NULL) {
> +    return EFI_INVALID_PARAMETER;
> +  }
> +
> +  if (Time->Year < RTC_DEFAULT_MIN_YEAR ||
> +      Time->Year > RTC_DEFAULT_MAX_YEAR)
> +  {
> +    return EFI_INVALID_PARAMETER;
> +  }
> +
> +  Data = (UINT8 *)RtcBufVir;
> +  Data[PCF85063_OFFSET_SEC] = PCF85063_SEC_ENC (Time->Second);
> +  Data[PCF85063_OFFSET_MIN] = PCF85063_MIN_ENC (Time->Minute);
> +  Data[PCF85063_OFFSET_HR]  = PCF85063_HR_ENC (Time->Hour);
> +  Data[PCF85063_OFFSET_DAY] = PCF85063_DAY_ENC (Time->Day);
> +  Data[PCF85063_OFFSET_MON] = PCF85063_MON_ENC (Time->Month);
> +  Data[PCF85063_OFFSET_YEA] = PCF85063_YEA_ENC (Time->Year - RTC_DEFAULT_MIN_YEAR);
> +
> +  return RtcI2cWrite (RTC_ADDR, RtcBufVir, RTC_DATA_BUF_LEN);
> +}
> +
> +/**
> + * Callback function for hardware platform to convert data pointers to virtual address
> + */
> +VOID
> +EFIAPI
> +PlatformVirtualAddressChangeEvent (
> +  VOID
> +  )
> +{
> +  EfiConvertPointer (0x0, (VOID **)&RtcBufVir);
> +}
> +
> +/**
> + * Callback function for hardware platform to initialize private data
> + *
> + *
> + * @retval EFI_SUCCESS           The operation completed successfully.
> + * @retval Others                The error status indicates the error
> + */
> +EFI_STATUS
> +EFIAPI
> +PlatformInitialize (
> +  VOID
> +  )
> +{
> +  EFI_STATUS Status;
> +
> +  /*
> +   * Allocate the buffer for RTC data
> +   * The buffer can be accessible after ExitBootServices
> +   */
> +  RtcBufVir = (UINT64)AllocateRuntimeZeroPool (RTC_DATA_BUF_LEN);
> +  ASSERT_EFI_ERROR (RtcBufVir);
> +  RtcBufPhy = (UINT64)RtcBufVir;
> +
> +  Status = I2cSetupRuntime (I2C_RTC_BUS_ADDRESS);
> +  ASSERT_EFI_ERROR (Status);
> +  if (EFI_ERROR (Status)) {
> +    DEBUG ((
> +      DEBUG_ERROR,
> +      "%a:%d I2cSetupRuntime() failed - %r \n",
> +      __FUNCTION__,
> +      __LINE__,
> +      Status
> +      ));
> +    return Status;
> +  }
> +
> +  Status = GpioSetupRuntime (I2C_RTC_ACCESS_GPIO_PIN);
> +  ASSERT_EFI_ERROR (Status);
> +  if (EFI_ERROR (Status)) {
> +    DEBUG ((
> +      DEBUG_ERROR,
> +      "%a:%d GpioSetupRuntime() failed - %r \n",
> +      __FUNCTION__,
> +      __LINE__,
> +      Status
> +      ));
> +    return Status;
> +  }
> +
> +  return EFI_SUCCESS;
> +}
> diff --git a/Platform/Ampere/JadePkg/Library/PCF85063RealTimeClockLib/PCF85063RealTimeClockLib.c b/Platform/Ampere/JadePkg/Library/PCF85063RealTimeClockLib/PCF85063RealTimeClockLib.c
> new file mode 100755
> index 000000000000..ef8c71e92c18
> --- /dev/null
> +++ b/Platform/Ampere/JadePkg/Library/PCF85063RealTimeClockLib/PCF85063RealTimeClockLib.c
> @@ -0,0 +1,257 @@
> +/** @file
> +
> +  Copyright (c) 2020 - 2021, Ampere Computing LLC. All rights reserved.<BR>
> +
> +  SPDX-License-Identifier: BSD-2-Clause-Patent
> +
> +**/
> +
> +#include <PiDxe.h>
> +#include <Uefi.h>
> +
> +#include <Guid/EventGroup.h>
> +#include <Library/ArmGenericTimerCounterLib.h>
> +#include <Library/ArmLib.h>
> +#include <Library/BaseLib.h>
> +#include <Library/DebugLib.h>
> +#include <Library/DxeServicesTableLib.h>
> +#include <Library/MemoryAllocationLib.h>
> +#include <Library/RealTimeClockLib.h>
> +#include <Library/TimeBaseLib.h>
> +#include <Library/UefiBootServicesTableLib.h>
> +#include <Library/UefiLib.h>
> +#include <Library/UefiRuntimeLib.h>
> +#include <Library/UefiRuntimeServicesTableLib.h>
> +#include <Protocol/RealTimeClock.h>
> +
> +#include "PCF85063.h"
> +
> +#define TICKS_PER_SEC     (ArmGenericTimerGetTimerFreq ())
> +
> +STATIC EFI_EVENT          mVirtualAddressChangeEvent = NULL;
> +
> +STATIC UINT64             mLastSavedSystemCount = 0;
> +STATIC UINT64             mLastSavedTimeEpoch = 0;
> +
> +/**
> + * Returns the current time and date information, and the time-keeping capabilities
> + * of the hardware platform.
> + *
> + * @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;
> +  UINT64        CurrentSystemCount;
> +  UINT64        TimeElapsed;
> +  UINTN         EpochSeconds;
> +
> +  if ((mLastSavedTimeEpoch == 0) || EfiAtRuntime ()) {
> +    Status = PlatformGetTime (Time);
> +    if (EFI_ERROR (Status)) {
> +      // Failed to read platform RTC so create fake time
> +      Time->Second = 0;
> +      Time->Minute = 0;
> +      Time->Hour = 10;
> +      Time->Day = 1;
> +      Time->Month = 1;
> +      Time->Year = 2017;
> +    }
> +
> +    EpochSeconds = EfiTimeToEpoch (Time);
> +    if (!EfiAtRuntime ()) {
> +      mLastSavedTimeEpoch = EpochSeconds;
> +      mLastSavedSystemCount = ArmGenericTimerGetSystemCount ();
> +    }
> +  } else {
> +    CurrentSystemCount = ArmGenericTimerGetSystemCount ();
> +    if (CurrentSystemCount >= mLastSavedSystemCount) {
> +      TimeElapsed = (CurrentSystemCount - mLastSavedSystemCount) / MultU64x32 (1, TICKS_PER_SEC);
> +      EpochSeconds = mLastSavedTimeEpoch + TimeElapsed;
> +    } else {
> +      // System counter overflow 64 bits
> +      // Call GetTime again to read the date from RTC HW, not using generic timer system counter
> +      mLastSavedTimeEpoch = 0;
> +      return LibGetTime (Time, Capabilities);
> +    }
> +  }
> +
> +  // Adjust for the correct timezone
> +  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 adjusted time, i.e. spring forwards one hour
> +    EpochSeconds += SEC_PER_HOUR;
> +  }
> +
> +  EpochToEfiTime (EpochSeconds, Time);
> +
> +  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;
> +
> +  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, i.e. fall back one hour
> +  if ((Time->Daylight & EFI_TIME_IN_DAYLIGHT) == EFI_TIME_IN_DAYLIGHT) {
> +    EpochSeconds -= SEC_PER_HOUR;
> +  }
> +
> +  EpochToEfiTime (EpochSeconds, Time);
> +
> +  Status = PlatformSetTime (Time);
> +  if (EFI_ERROR (Status)) {
> +    return Status;
> +  }
> +
> +  if (!EfiAtRuntime ()) {
> +    mLastSavedTimeEpoch = EpochSeconds;
> +    mLastSavedSystemCount = ArmGenericTimerGetSystemCount ();
> +  }
> +
> +  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;
> +}
> +
> +/**
> +  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
> +  )
> +{
> +  //
> +  // Only needed if you are going to support the OS calling RTC functions in virtual mode.
> +  // You will need to call EfiConvertPointer (). To convert any stored physical addresses
> +  // to virtual address. After the OS transitions to calling in virtual mode, all future
> +  // runtime calls will be made in virtual mode.
> +  //
> +  PlatformVirtualAddressChangeEvent ();
> +}
> +
> +/**
> + * 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
> +  )
> +{
> +  EFI_STATUS    Status;
> +
> +  Status = PlatformInitialize ();
> +  if (EFI_ERROR (Status)) {
> +    return Status;
> +  }
> +
> +  //
> +  // Register for the virtual address change event
> +  //
> +  Status = gBS->CreateEventEx (
> +                  EVT_NOTIFY_SIGNAL,
> +                  TPL_NOTIFY,
> +                  LibRtcVirtualNotifyEvent,
> +                  NULL,
> +                  &gEfiEventVirtualAddressChangeGuid,
> +                  &mVirtualAddressChangeEvent
> +                  );
> +  ASSERT_EFI_ERROR (Status);
> +
> +  return EFI_SUCCESS;
> +}
> -- 
> 2.17.1
>