Re: [PATCH v1 2/6] PcAtChipsetPkg: Add MMIO Support to RTC driver

[Leif Lindholm <leif.lindholm@linaro.org>]

On Fri, Oct 12, 2018 at 03:40:05PM +0100, Sami Mujawar wrote:
> 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.
> 
> 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.
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
> ---
> The changes can be seen at https://github.com/samimujawar/edk2/commit/d9fa7df2204c12883a795c7df429578c310725bf
> 
> Notes:
>     v1:
>     - Add support to read/write from RTC registers using MMIO access  [SAMI]
> 
>  PcAtChipsetPkg/PcAtChipsetPkg.dec                                          |   8 ++
>  PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c                         |  38 ++++++-
>  PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtcEntry.c                    | 112 +++++++++++++++++++-
>  PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcatRealTimeClockRuntimeDxe.inf |   8 ++
>  4 files changed, 162 insertions(+), 4 deletions(-)
> 
> diff --git a/PcAtChipsetPkg/PcAtChipsetPkg.dec b/PcAtChipsetPkg/PcAtChipsetPkg.dec
> index 0e66ff0ba3770cf765cfe36d592151d72eaa238a..5aaf5e73811c4dba3b83768f1535e028938ead1f 100644
> --- a/PcAtChipsetPkg/PcAtChipsetPkg.dec
> +++ b/PcAtChipsetPkg/PcAtChipsetPkg.dec
> @@ -6,6 +6,7 @@
>  #
>  # Copyright (c) 2009 - 2018, Intel Corporation. All rights reserved.<BR>
>  # Copyright (c) 2017, AMD Inc. All rights reserved.<BR>
> +# Copyright (c) 2018, ARM Limited. All rights reserved.<BR>
>  #
>  # This program and the accompanying materials
>  # are licensed and made available under the terms and conditions of the BSD License
> @@ -202,5 +203,12 @@ [PcdsFixedAtBuild, PcdsPatchableInModule]
>    # @Prompt RTC Target Register address
>    gPcAtChipsetPkgTokenSpaceGuid.PcdRtcTargetRegister|0x71|UINT8|0x0000001F
>  
> +  ## 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|0x00000020
> +
>  [UserExtensions.TianoCore."ExtraFiles"]
>    PcAtChipsetPkgExtra.uni
> diff --git a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c
> index 7965eb8aa55b92caef7a63834695506123935e2d..ee746add57b9778bf09a4d9eb6881d06caa14aba 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, ARM Limited. All rights reserved.<BR>
>  
>  This program and the accompanying materials
>  are licensed and made available under the terms and conditions of the BSD License
> @@ -16,6 +17,8 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
>  
>  #include "PcRtc.h"
>  
> +extern EFI_PHYSICAL_ADDRESS   mRtcRegisterBase;
> +
>  //
>  // Days of month.
>  //
> @@ -72,7 +75,21 @@ RtcRead (
>    IN  UINT8 Address
>    )
>  {
> -  IoWrite8 (PcdGet8 (PcdRtcIndexRegister), (UINT8) (Address | (UINT8) (IoRead8 (PcdGet8 (PcdRtcIndexRegister)) & 0x80)));
> +  if (FixedPcdGetBool (PcdRtcUseMmio)) {
> +    MmioWrite8 (
> +      mRtcRegisterBase,
> +      (UINT8)(Address | (UINT8)(MmioRead8 (mRtcRegisterBase) & 0x80))
> +      );
> +    return MmioRead8 (
> +             mRtcRegisterBase + (PcdGet8 (PcdRtcTargetRegister) -
> +               PcdGet8 (PcdRtcIndexRegister))
> +             );
> +  }
> +
> +  IoWrite8 (
> +    PcdGet8 (PcdRtcIndexRegister),
> +    (UINT8)(Address | (UINT8)(IoRead8 (PcdGet8 (PcdRtcIndexRegister)) & 0x80))
> +    );
>    return IoRead8 (PcdGet8 (PcdRtcTargetRegister));

So, this isn't my package, but I would much rather see this solved
with local (STATIC) wrapper functions (i.e. RtcRead*/RtcWrite*) for
the accessors instead of conditionalising which one to use at every
call site.

/
    Leif

>  }
>  
> @@ -90,8 +107,23 @@ RtcWrite (
>    IN  UINT8   Data
>    )
>  {
> -  IoWrite8 (PcdGet8 (PcdRtcIndexRegister), (UINT8) (Address | (UINT8) (IoRead8 (PcdGet8 (PcdRtcIndexRegister)) & 0x80)));
> -  IoWrite8 (PcdGet8 (PcdRtcTargetRegister), Data);
> +  if (FixedPcdGetBool (PcdRtcUseMmio)) {
> +    MmioWrite8 (
> +      mRtcRegisterBase,
> +      (UINT8)(Address | (UINT8)(MmioRead8 (mRtcRegisterBase) & 0x80))
> +      );
> +    MmioWrite8 (
> +      mRtcRegisterBase + (PcdGet8 (PcdRtcTargetRegister) -
> +        PcdGet8 (PcdRtcIndexRegister)),
> +      Data
> +      );
> +  } else {
> +    IoWrite8 (
> +      PcdGet8 (PcdRtcIndexRegister),
> +      (UINT8)(Address | (UINT8)(IoRead8 (PcdGet8 (PcdRtcIndexRegister)) & 0x80))
> +      );
> +    IoWrite8 (PcdGet8 (PcdRtcTargetRegister), Data);
> +  }
>  }
>  
>  /**
> diff --git a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtcEntry.c b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtcEntry.c
> index 56ddc3ed5b1accc2b1a99ab4515f851f89fb6e43..d6d7251309001a203282eb7022cc71ac4f0ef62e 100644
> --- a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtcEntry.c
> +++ b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtcEntry.c
> @@ -2,6 +2,7 @@
>    Provides Set/Get time operations.
>  
>  Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
> +Copyright (c) 2018, ARM Limited. All rights reserved.<BR>
>  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
> @@ -12,12 +13,17 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
>  
>  **/
>  
> +#include <Library/DxeServicesTableLib.h>
>  #include "PcRtc.h"
>  
>  PC_RTC_MODULE_GLOBALS  mModuleGlobal;
>  
>  EFI_HANDLE             mHandle = NULL;
>  
> +STATIC EFI_EVENT       mVirtualAddrChangeEvent;
> +
> +EFI_PHYSICAL_ADDRESS   mRtcRegisterBase;
> +
>  /**
>    Returns the current time and date information, and the time-keeping capabilities
>    of the hardware platform.
> @@ -112,6 +118,29 @@ 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);
> +}
> +
> +/**
>    The user Entry Point for PcRTC module.
>  
>    This is the entrhy point for PcRTC module. It installs the UEFI runtime service
> @@ -133,10 +162,75 @@ InitializePcRtc (
>  {
>    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);
>  
> @@ -171,7 +265,23 @@ 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/PcatRealTimeClockRuntimeDxe.inf b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcatRealTimeClockRuntimeDxe.inf
> index 876298e1e0f3745cd3213509ffed4e091fbedef8..2dee5a77cfc23878a64a809bcb64e3745230ea5a 100644
> --- a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcatRealTimeClockRuntimeDxe.inf
> +++ b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcatRealTimeClockRuntimeDxe.inf
> @@ -6,6 +6,7 @@
>  #
>  # Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
>  # Copyright (c) 2017, AMD Inc. All rights reserved.<BR>
> +# Copyright (c) 2018, ARM Limited. All rights reserved.<BR>
>  #
>  # This program and the accompanying materials
>  # are licensed and made available under the terms and conditions of the BSD License
> @@ -55,6 +56,7 @@ [LibraryClasses]
>    BaseLib
>    PcdLib
>    ReportStatusCodeLib
> +  DxeServicesTableLib
>  
>  [Protocols]
>    gEfiRealTimeClockArchProtocolGuid             ## PRODUCES
> @@ -68,10 +70,13 @@ [Guids]
>    ## SOMETIMES_CONSUMES ## SystemTable
>    gEfiAcpiTableGuid
>  
> +  gEfiEventVirtualAddressChangeGuid
> +
>  [FixedPcd]
>    gPcAtChipsetPkgTokenSpaceGuid.PcdInitialValueRtcRegisterA     ## CONSUMES
>    gPcAtChipsetPkgTokenSpaceGuid.PcdInitialValueRtcRegisterB     ## CONSUMES
>    gPcAtChipsetPkgTokenSpaceGuid.PcdInitialValueRtcRegisterD     ## CONSUMES
> +  gPcAtChipsetPkgTokenSpaceGuid.PcdRtcUseMmio                   ## CONSUMES
>  
>  [Pcd]
>    gEfiMdeModulePkgTokenSpaceGuid.PcdRealTimeClockUpdateTimeout  ## CONSUMES
> @@ -83,5 +88,8 @@ [Pcd]
>  [Depex]
>    gEfiVariableArchProtocolGuid AND gEfiVariableWriteArchProtocolGuid
>  
> +[Depex.common.DXE_RUNTIME_DRIVER]
> +  gEfiCpuArchProtocolGuid
> +
>  [UserExtensions.TianoCore."ExtraFiles"]
>    PcRtcExtra.uni
> -- 
> 'Guid(CE165669-3EF3-493F-B85D-6190EE5B9759)'
> 
>