Re: [edk2-devel] [PATCH v2 01/11] PcAtChipsetPkg: Add MMIO Support to RTC driver

["Guomin Jiang" <guomin.jiang@intel.com>]

I am interest with the patch,

I am busy and may review it after August.

> -----Original Message-----
> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of André
> Przywara
> Sent: Friday, May 15, 2020 6:51 PM
> To: Sami Mujawar <sami.mujawar@arm.com>; devel@edk2.groups.io
> Cc: ard.biesheuvel@arm.com; leif@nuviainc.com; Ni, Ray
> <ray.ni@intel.com>; Alexandru.Elisei@arm.com; Matteo.Carlini@arm.com;
> Laura.Moretta@arm.com; nd@arm.com
> Subject: Re: [edk2-devel] [PATCH v2 01/11] PcAtChipsetPkg: Add MMIO
> Support to RTC driver
> 
> On 14/05/2020 09:40, Sami Mujawar wrote:
> 
> Hi Sami,
> 
> many thanks for your work on that!
> 
> > Some virtual machine managers like kvmtool emulate the MC146818 RTC
> > controller in the MMIO space so that architectures that do not support
> > I/O Mapped I/O can use the RTC. This patch adds MMIO support to the
> > RTC controller driver.
> 
> Is there any chance you could read the MMIO base address from the DT? I
> sent a kvmtool patch to add the missing DT node[1].
> The compatible string would be "motorola,mc146818", with just the usual reg
> property.
> Maybe you could fall back to the current 0x70/0x71, if there is no DT node?
> 
> For a start, this low address (0x70/0x71) causes issues, so we probably need
> to move this permanently.
> But also we want to introduce a more flexible memory layout, so devices can
> move depending on command line parameters.
> 
> It would be great if EDK-2 could cover that from the beginning, so that we
> don't end up with compatibility issues.
> 
> Cheers,
> Andre
> 
> [1] https://lists.cs.columbia.edu/pipermail/kvmarm/2020-May/040703.html
> >
> > The PCD PcdRtcUseMmio has been added to select I/O or MMIO support.
> >   If PcdRtcUseMmio is:
> >     TRUE  - Indicates the RTC port registers are in MMIO space.
> >     FALSE - Indicates the RTC port registers are in I/O space.
> >             Default is I/O space.
> >
> > When MMIO support is selected (PcdRtcUseMmio == TRUE) the driver
> maps
> > the MMIO region used by the RTC as runtime memory so that the RTC
> > registers are accessible post ExitBootServices.
> >
> > Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
> > ---
> >
> > Notes:
> >     v2:
> >       - Code review comments incorporated.                              [Sami]
> >
> >     v1:
> >       - Add support to read/write from RTC registers using MMIO access
> [Sami]
> >       - Use wrapper functions for RtcRead/Write accessors               [Leif]
> >         Ref: https://edk2.groups.io/g/devel/topic/30915281#30695
> >
> >  PcAtChipsetPkg/PcAtChipsetPkg.dec                                          |   8 ++
> >  PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c                         | 117
> ++++++++++++++++--
> >  PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.h                         |  31
> +++++
> >  PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtcEntry.c                    |
> 130 +++++++++++++++++++-
> >
> PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcatRealTimeClockRuntime
> Dxe.inf |   8 ++
> >  5 files changed, 280 insertions(+), 14 deletions(-)
> >
> > diff --git a/PcAtChipsetPkg/PcAtChipsetPkg.dec
> > b/PcAtChipsetPkg/PcAtChipsetPkg.dec
> > index
> >
> 88de5cceea593176c3a2425a5963b66b789f2b9e..76d0c7eda69bb505914ba904
> e09c
> > 89de170f69ae 100644
> > --- a/PcAtChipsetPkg/PcAtChipsetPkg.dec
> > +++ b/PcAtChipsetPkg/PcAtChipsetPkg.dec
> > @@ -6,6 +6,7 @@
> >  #
> >  # Copyright (c) 2009 - 2019, Intel Corporation. All rights
> > reserved.<BR>  # Copyright (c) 2017, AMD Inc. All rights reserved.<BR>
> > +# Copyright (c) 2018, ARM Limited. All rights reserved.<BR>
> >  #
> >  # SPDX-License-Identifier: BSD-2-Clause-Patent  # @@ -142,5 +143,12
> > @@ [PcdsFixedAtBuild, PcdsPatchableInModule]
> >    # @Prompt RTC Update Timeout Value.
> >
> >
> gPcAtChipsetPkgTokenSpaceGuid.PcdRealTimeClockUpdateTimeout|100000
> |UIN
> > T32|0x00000020
> >
> > +  ## Indicates the RTC port registers are in MMIO space, or in I/O space.
> > +  #  Default is I/O space.<BR><BR>
> > +  #   TRUE  - RTC port registers are in MMIO space.<BR>
> > +  #   FALSE - RTC port registers are in I/O space.<BR>
> > +  # @Prompt RTC port registers use MMIO.
> > +
> > +
> gPcAtChipsetPkgTokenSpaceGuid.PcdRtcUseMmio|FALSE|BOOLEAN|0x0000
> 0021
> > +
> >  [UserExtensions.TianoCore."ExtraFiles"]
> >    PcAtChipsetPkgExtra.uni
> > diff --git a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c
> > b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c
> > index
> >
> 52af17941786ef81c3911512ee64551724e67209..df8dea83ab27bbba12351096d
> 1bf
> > d9ea31accb60 100644
> > --- a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c
> > +++ b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c
> > @@ -3,6 +3,7 @@
> >
> >  Copyright (c) 2006 - 2018, Intel Corporation. All rights
> > reserved.<BR>  Copyright (c) 2017, AMD Inc. All rights reserved.<BR>
> > +Copyright (c) 2018 - 2020, ARM Limited. All rights reserved.<BR>
> >
> >  SPDX-License-Identifier: BSD-2-Clause-Patent
> >
> > @@ -10,6 +11,8 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
> >
> >  #include "PcRtc.h"
> >
> > +extern EFI_PHYSICAL_ADDRESS   mRtcRegisterBase;
> > +
> >  //
> >  // Days of month.
> >  //
> > @@ -21,6 +24,28 @@ UINTN mDayOfMonth[] = { 31, 29, 31, 30, 31, 30, 31,
> > 31, 30, 31, 30, 31 };
> >  CHAR16 mTimeZoneVariableName[] = L"RTC";
> >
> >  /**
> > +  A function pointer that evaluates to a function that reads the RTC
> > + content  through its registers either using IO or MMIO access.
> > +
> > +  @param  Address   Address offset of RTC. It is recommended to use
> > +                    macros such as RTC_ADDRESS_SECONDS.
> > +
> > +  @return The data of UINT8 type read from RTC.
> > +**/
> > +RTC_READ  RtcRead;
> > +
> > +/**
> > +  A function pointer that evaluates to a function that reads the RTC
> > +content
> > +  through its registers either using IO or MMIO access.
> > +
> > +  @param  Address   Address offset of RTC. It is recommended to use
> > +                    macros such as RTC_ADDRESS_SECONDS.
> > +
> > +  @return The data of UINT8 type read from RTC.
> > +**/
> > +RTC_WRITE RtcWrite;
> > +
> > +/**
> >    Compare the Hour, Minute and Second of the From time and the To time.
> >
> >    Only compare H/M/S in EFI_TIME and ignore other fields here.
> > @@ -54,41 +79,99 @@ IsWithinOneDay (
> >    );
> >
> >  /**
> > -  Read RTC content through its registers.
> > +  Read RTC content through its registers using IO access.
> >
> > -  @param  Address  Address offset of RTC. It is recommended to use
> macros such as
> > -                   RTC_ADDRESS_SECONDS.
> > +  @param  Address   Address offset of RTC. It is recommended to use
> > +                    macros such as RTC_ADDRESS_SECONDS.
> >
> >    @return The data of UINT8 type read from RTC.
> >  **/
> > +STATIC
> >  UINT8
> > -RtcRead (
> > +IoRtcRead (
> >    IN  UINT8 Address
> >    )
> >  {
> > -  IoWrite8 (PcdGet8 (PcdRtcIndexRegister), (UINT8) (Address | (UINT8)
> > (IoRead8 (PcdGet8 (PcdRtcIndexRegister)) & 0x80)));
> > +  IoWrite8 (
> > +    PcdGet8 (PcdRtcIndexRegister),
> > +    (UINT8)(Address | (UINT8)(IoRead8 (PcdGet8 (PcdRtcIndexRegister)) &
> 0x80))
> > +    );
> >    return IoRead8 (PcdGet8 (PcdRtcTargetRegister));  }
> >
> >  /**
> > -  Write RTC through its registers.
> > +  Write RTC through its registers  using IO access.
> >
> > -  @param  Address  Address offset of RTC. It is recommended to use
> macros such as
> > -                   RTC_ADDRESS_SECONDS.
> > -  @param  Data     The content you want to write into RTC.
> > +  @param  Address   Address offset of RTC. It is recommended to use
> > +                    macros such as RTC_ADDRESS_SECONDS.
> > +  @param  Data      The content you want to write into RTC.
> >
> >  **/
> > +STATIC
> >  VOID
> > -RtcWrite (
> > +IoRtcWrite (
> >    IN  UINT8   Address,
> >    IN  UINT8   Data
> >    )
> >  {
> > -  IoWrite8 (PcdGet8 (PcdRtcIndexRegister), (UINT8) (Address | (UINT8)
> > (IoRead8 (PcdGet8 (PcdRtcIndexRegister)) & 0x80)));
> > +  IoWrite8 (
> > +    PcdGet8 (PcdRtcIndexRegister),
> > +    (UINT8)(Address | (UINT8)(IoRead8 (PcdGet8 (PcdRtcIndexRegister)) &
> 0x80))
> > +    );
> >    IoWrite8 (PcdGet8 (PcdRtcTargetRegister), Data);  }
> >
> >  /**
> > +  Read RTC content through its registers using MMIO access.
> > +
> > +  @param  Address   Address offset of RTC. It is recommended to use
> > +                    macros such as RTC_ADDRESS_SECONDS.
> > +
> > +  @return The data of UINT8 type read from RTC.
> > +**/
> > +STATIC
> > +UINT8
> > +MmioRtcRead (
> > +  IN  UINT8 Address
> > +  )
> > +{
> > +  MmioWrite8 (
> > +    mRtcRegisterBase,
> > +    (UINT8)(Address | (UINT8)(MmioRead8 (mRtcRegisterBase) & 0x80))
> > +    );
> > +  return MmioRead8 (
> > +           mRtcRegisterBase + (PcdGet8 (PcdRtcTargetRegister) -
> > +             PcdGet8 (PcdRtcIndexRegister))
> > +           );
> > +}
> > +
> > +/**
> > +  Write RTC through its registers using MMIO access.
> > +
> > +  @param  Address   Address offset of RTC. It is recommended to use
> > +                    macros such as RTC_ADDRESS_SECONDS.
> > +  @param  Data      The content you want to write into RTC.
> > +
> > +**/
> > +STATIC
> > +VOID
> > +MmioRtcWrite (
> > +  IN  UINT8   Address,
> > +  IN  UINT8   Data
> > +  )
> > +{
> > +  MmioWrite8 (
> > +    mRtcRegisterBase,
> > +    (UINT8)(Address | (UINT8)(MmioRead8 (mRtcRegisterBase) & 0x80))
> > +    );
> > +  MmioWrite8 (
> > +    mRtcRegisterBase + (PcdGet8 (PcdRtcTargetRegister) -
> > +      PcdGet8 (PcdRtcIndexRegister)),
> > +    Data
> > +    );
> > +}
> > +
> > +/**
> >    Initialize RTC.
> >
> >    @param  Global            For global use inside this module.
> > @@ -113,6 +196,18 @@ PcRtcInit (
> >    BOOLEAN         Pending;
> >
> >    //
> > +  // Initialize the RtcRead and RtcWrite functions  // based on the
> > + chosen IO/MMIO access.
> > +  //
> > +  if (FixedPcdGetBool (PcdRtcUseMmio)) {
> > +    RtcRead = MmioRtcRead;
> > +    RtcWrite = MmioRtcWrite;
> > +  } else {
> > +    RtcRead = IoRtcRead;
> > +    RtcWrite = IoRtcWrite;
> > +  }
> > +
> > +  //
> >    // Acquire RTC Lock to make access to RTC atomic
> >    //
> >    if (!EfiAtRuntime ()) {
> > diff --git a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.h
> > b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.h
> > index
> >
> 47293ce44c5a1f4792892892f7da40d7f0a5a001..e64dbbea48f7f0d2f317c65c2e
> 4b
> > 93e7b1888efc 100644
> > --- a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.h
> > +++ b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.h
> > @@ -3,6 +3,7 @@
> >
> >  Copyright (c) 2006 - 2018, Intel Corporation. All rights
> > reserved.<BR>  Copyright (c) 2017, AMD Inc. All rights reserved.<BR>
> > +Copyright (c) 2019 - 2020, ARM Limited. All rights reserved.<BR>
> >
> >  SPDX-License-Identifier: BSD-2-Clause-Patent
> >
> > @@ -371,4 +372,34 @@ PcRtcAcpiTableChangeCallback (
> >    IN EFI_EVENT        Event,
> >    IN VOID             *Context
> >    );
> > +
> > +/**
> > +  Function pointer to Read RTC content through its registers.
> > +
> > +  @param  Address   Address offset of RTC. It is recommended to use
> > +                    macros such as RTC_ADDRESS_SECONDS.
> > +
> > +  @return The data of UINT8 type read from RTC.
> > +**/
> > +typedef
> > +UINT8
> > +(EFIAPI *RTC_READ) (
> > +  IN  UINT8 Address
> > +  );
> > +
> > +/**
> > +  Function pointer to Write RTC through its registers.
> > +
> > +  @param  Address   Address offset of RTC. It is recommended to use
> > +                    macros such as RTC_ADDRESS_SECONDS.
> > +  @param  Data      The content you want to write into RTC.
> > +
> > +**/
> > +typedef
> > +VOID
> > +(EFIAPI *RTC_WRITE) (
> > +  IN  UINT8   Address,
> > +  IN  UINT8   Data
> > +  );
> > +
> >  #endif
> > diff --git a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtcEntry.c
> > b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtcEntry.c
> > index
> >
> ccda6331373bfe4069b0a59495b5e5cc731c8fc8..5d5dbeaf970ca8eb291c1e094f
> d7
> > 64d201f9071e 100644
> > --- a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtcEntry.c
> > +++ b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtcEntry.c
> > @@ -2,16 +2,32 @@
> >    Provides Set/Get time operations.
> >
> >  Copyright (c) 2006 - 2018, Intel Corporation. All rights
> > reserved.<BR>
> > +Copyright (c) 2018 - 2020, ARM Limited. All rights reserved.<BR>
> >  SPDX-License-Identifier: BSD-2-Clause-Patent
> >
> >  **/
> >
> > +#include <Library/DxeServicesTableLib.h>
> >  #include "PcRtc.h"
> >
> >  PC_RTC_MODULE_GLOBALS  mModuleGlobal;
> >
> >  EFI_HANDLE             mHandle = NULL;
> >
> > +STATIC EFI_EVENT       mVirtualAddrChangeEvent;
> > +
> > +EFI_PHYSICAL_ADDRESS   mRtcRegisterBase;
> > +
> > +//
> > +// Function pointer for the Rtc Read interface function //
> > +extern RTC_READ   RtcRead;
> > +
> > +//
> > +// Function pointer for the Rtc Write interface function // extern
> > +RTC_WRITE  RtcWrite;
> > +
> >  /**
> >    Returns the current time and date information, and the time-keeping
> capabilities
> >    of the hardware platform.
> > @@ -106,6 +122,33 @@ PcRtcEfiSetWakeupTime (  }
> >
> >  /**
> > +  Fixup internal data so that EFI can be called 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.
> > +  EfiConvertPointer (0x0, (VOID**)&mRtcRegisterBase);
> > +
> > +  // Convert the RtcRead and RtcWrite pointers for runtime use.
> > +  EfiConvertPointer (0x0, (VOID**)&RtcRead);
> > +  EfiConvertPointer (0x0, (VOID**)&RtcWrite); }
> > +
> > +/**
> >    The user Entry Point for PcRTC module.
> >
> >    This is the entry point for PcRTC module. It installs the UEFI
> > runtime service @@ -125,12 +168,77 @@ InitializePcRtc (
> >    IN EFI_SYSTEM_TABLE                      *SystemTable
> >    )
> >  {
> > -  EFI_STATUS  Status;
> > -  EFI_EVENT   Event;
> > +  EFI_STATUS             Status;
> > +  EFI_EVENT              Event;
> > +  EFI_PHYSICAL_ADDRESS   RtcPageBase;
> >
> >    EfiInitializeLock (&mModuleGlobal.RtcLock, TPL_CALLBACK);
> >    mModuleGlobal.CenturyRtcAddress = GetCenturyRtcAddress ();
> >
> > +  if (FixedPcdGetBool (PcdRtcUseMmio)) {
> > +    mRtcRegisterBase = PcdGet8 (PcdRtcIndexRegister);
> > +    RtcPageBase = mRtcRegisterBase & ~(EFI_PAGE_SIZE - 1);
> > +
> > +    // Declare the controller as EFI_MEMORY_RUNTIME
> > +    Status = gDS->AddMemorySpace (
> > +                    EfiGcdMemoryTypeMemoryMappedIo,
> > +                    RtcPageBase,
> > +                    EFI_PAGE_SIZE,
> > +                    EFI_MEMORY_UC | EFI_MEMORY_RUNTIME
> > +                    );
> > +    if (EFI_ERROR (Status)) {
> > +      DEBUG ((
> > +        DEBUG_ERROR, "Failed to add memory space. Status = %r\n",
> > +        Status
> > +        ));
> > +      return Status;
> > +    }
> > +
> > +    Status = gDS->AllocateMemorySpace (
> > +                    EfiGcdAllocateAddress,
> > +                    EfiGcdMemoryTypeMemoryMappedIo,
> > +                    0,
> > +                    EFI_PAGE_SIZE,
> > +                    &RtcPageBase,
> > +                    ImageHandle,
> > +                    NULL
> > +                    );
> > +    if (EFI_ERROR (Status)) {
> > +      DEBUG ((
> > +        DEBUG_ERROR,
> > +        "Failed to allocate memory space. Status = %r\n",
> > +        Status
> > +        ));
> > +      gDS->RemoveMemorySpace (
> > +             RtcPageBase,
> > +             EFI_PAGE_SIZE
> > +             );
> > +      return Status;
> > +    }
> > +
> > +    Status = gDS->SetMemorySpaceAttributes (
> > +                    RtcPageBase,
> > +                    EFI_PAGE_SIZE,
> > +                    EFI_MEMORY_UC | EFI_MEMORY_RUNTIME
> > +                    );
> > +    if (EFI_ERROR (Status)) {
> > +      DEBUG ((
> > +        DEBUG_ERROR,
> > +        "Failed to set memory attributes. Status = %r\n",
> > +        Status
> > +        ));
> > +      gDS->FreeMemorySpace (
> > +               RtcPageBase,
> > +               EFI_PAGE_SIZE
> > +               );
> > +      gDS->RemoveMemorySpace (
> > +             RtcPageBase,
> > +             EFI_PAGE_SIZE
> > +             );
> > +      return Status;
> > +    }
> > +  }
> > +
> >    Status = PcRtcInit (&mModuleGlobal);
> >    ASSERT_EFI_ERROR (Status);
> >
> > @@ -165,7 +273,23 @@ InitializePcRtc (
> >                    NULL,
> >                    NULL
> >                    );
> > -  ASSERT_EFI_ERROR (Status);
> > +  if (EFI_ERROR (Status)) {
> > +    ASSERT_EFI_ERROR (Status);
> > +    return Status;
> > +  }
> > +
> > +  if (FixedPcdGetBool (PcdRtcUseMmio)) {
> > +    // Register for the virtual address change event
> > +    Status = gBS->CreateEventEx (
> > +                    EVT_NOTIFY_SIGNAL,
> > +                    TPL_NOTIFY,
> > +                    LibRtcVirtualNotifyEvent,
> > +                    NULL,
> > +                    &gEfiEventVirtualAddressChangeGuid,
> > +                    &mVirtualAddrChangeEvent
> > +                    );
> > +    ASSERT_EFI_ERROR (Status);
> > +  }
> >
> >    return Status;
> >  }
> > diff --git
> >
> a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcatRealTimeClockRuntim
> eD
> > xe.inf
> >
> b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcatRealTimeClockRuntim
> eD
> > xe.inf index
> >
> c73ee98105e510f9e4e23c1a6c1e5c505325d2c9..3a373d11f8bfc7df0e4d00be8
> b43
> > e90bfa06b192 100644
> > ---
> >
> a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcatRealTimeClockRuntim
> eD
> > xe.inf
> > +++
> b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcatRealTimeClockRunt
> > +++ imeDxe.inf
> > @@ -6,6 +6,7 @@
> >  #
> >  # Copyright (c) 2006 - 2019, Intel Corporation. All rights
> > reserved.<BR>  # Copyright (c) 2017, AMD Inc. All rights reserved.<BR>
> > +# Copyright (c) 2018, ARM Limited. All rights reserved.<BR>
> >  #
> >  # SPDX-License-Identifier: BSD-2-Clause-Patent  # @@ -48,6 +49,7 @@
> > [LibraryClasses]
> >    BaseLib
> >    PcdLib
> >    ReportStatusCodeLib
> > +  DxeServicesTableLib
> >
> >  [Protocols]
> >    gEfiRealTimeClockArchProtocolGuid             ## PRODUCES
> > @@ -61,10 +63,13 @@ [Guids]
> >    ## SOMETIMES_CONSUMES ## SystemTable
> >    gEfiAcpiTableGuid
> >
> > +  gEfiEventVirtualAddressChangeGuid
> > +
> >  [FixedPcd]
> >    gPcAtChipsetPkgTokenSpaceGuid.PcdInitialValueRtcRegisterA     ##
> CONSUMES
> >    gPcAtChipsetPkgTokenSpaceGuid.PcdInitialValueRtcRegisterB     ##
> CONSUMES
> >    gPcAtChipsetPkgTokenSpaceGuid.PcdInitialValueRtcRegisterD     ##
> CONSUMES
> > +  gPcAtChipsetPkgTokenSpaceGuid.PcdRtcUseMmio                   ##
> CONSUMES
> >
> >  [Pcd]
> >    gPcAtChipsetPkgTokenSpaceGuid.PcdRealTimeClockUpdateTimeout   ##
> CONSUMES
> > @@ -76,5 +81,8 @@ [Pcd]
> >  [Depex]
> >    gEfiVariableArchProtocolGuid AND gEfiVariableWriteArchProtocolGuid
> >
> > +[Depex.common.DXE_RUNTIME_DRIVER]
> > +  gEfiCpuArchProtocolGuid
> > +
> >  [UserExtensions.TianoCore."ExtraFiles"]
> >    PcRtcExtra.uni
> >
> 
> 
>