Re: [PATCH v5 01/15] PcAtChipsetPkg: Add MMIO Support to RTC driver

["Laszlo Ersek" <lersek@redhat.com>]

Hi Ard,

On 10/05/20 12:58, Ard Biesheuvel wrote:
> On 10/2/20 11:13 PM, 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.
>>
>> Additionally two new PCDs PcdRtcIndexRegister64 and
>> PcdRtcTargetRegister64 have been introduced to provide the base
>> address for the RTC registers in the MMIO space.
>>
>> When MMIO support is selected (PcdRtcUseMmio == TRUE) the driver
>> converts the pointers to the RTC MMIO registers so that the
>> RTC registers are accessible post ExitBootServices.
>>
>> Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
>> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@arm.com>
> 
> Thanks for the resend.
> 
> Ray, do you have any concerns regarding this patch? The series looks
> otherwise ok, and I would like to get this merged this week.

Thank you very much for handling this. I've skimmed the series quickly
and it mostly adds new files. I think the risk of regressions is really
low. Please feel free to merge this from my side.

For wherever it applies in the series:

Acked-by: Laszlo Ersek <lersek@redhat.com>

Thanks
Laszlo



> 
> Guomin, you replied before that you were intending to review this patch
> after August. Do you still intend to do so?
> 
> If I don't hear from you by the end of this week, I am going to assume
> there are no objections from your side.
> 
> Thanks,
> Ard.
> 
> 
>> ---
>>
>> Notes:
>>      v5:
>>        - Updated based on review comments.                            
>> [Sami]
>>        - Drop the unnecessary whitespace and header changes to        
>> [Ard]
>>          PcRtc.h, and the whitespace changes to PcRtcEntry.c
>>          Ref: https://edk2.groups.io/g/devel/topic/75354083
>>           v4:
>>        - Updated based on review comments.                            
>> [Sami]
>>        - Use static helper functions instead of function pointers.    
>> [Ard]
>>          Ref: https://edk2.groups.io/g/devel/topic/75081468
>>           v3:
>>        - Make PcdRtcUseMmio a feature PCD.                            
>> [Sami]
>>        - Read the RTC MMIO base address from the DT.                  
>> [Andre]
>>        - Introduce PCDs for RTC Index and Target register base        
>> [Sami]
>>          address in the MMIO space.
>>        - Move RTC MMIO region mapping code to a separate platform     
>> [Sami]
>>          specific library. This library also reads the base addresses
>>          for the RTC from DT and configures the RTC Index and Target
>>          register PCDs.
>>          Ref: https://edk2.groups.io/g/devel/topic/74200905#60307
>>           v2:
>>        - Code review comments incorporated.                           
>> [Sami]
>>           v1:
>>        - Add support to read/write from RTC registers using           
>> [Sami]
>>          MMIO access
>>        - Use wrapper functions for RtcRead/Write accessors            
>> [Leif]
>>          Ref: https://edk2.groups.io/g/devel/topic/30915281#30695
>>
>>  
>> PcAtChipsetPkg/PcAtChipsetPkg.dec                                         
>> |  16 +++
>>  
>> PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c                        
>> | 120 ++++++++++++++++++--
>>  
>> PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtcEntry.c                   
>> |  54 ++++++++-
>>  
>> PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcatRealTimeClockRuntimeDxe.inf
>> |   8 ++
>>   4 files changed, 186 insertions(+), 12 deletions(-)
>>
>> diff --git a/PcAtChipsetPkg/PcAtChipsetPkg.dec
>> b/PcAtChipsetPkg/PcAtChipsetPkg.dec
>> index
>> 88de5cceea593176c3a2425a5963b66b789f2b9e..ed2d95550b8d153995b30cdc290cf3bb905e211b
>> 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 - 2020, ARM Limited. All rights reserved.<BR>
>>   #
>>   # SPDX-License-Identifier: BSD-2-Clause-Patent
>>   #
>> @@ -41,6 +42,13 @@ [PcdsFeatureFlag]
>>     # @Prompt Configure HPET to use MSI.
>>    
>> gPcAtChipsetPkgTokenSpaceGuid.PcdHpetMsiEnable|TRUE|BOOLEAN|0x00001000
>>   +  ## 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|0x00000021
>> +
>>   [PcdsFixedAtBuild, PcdsDynamic, PcdsDynamicEx, PcdsPatchableInModule]
>>     ## This PCD specifies the base address of the HPET timer.
>>     # @Prompt HPET base address.
>> @@ -68,6 +76,14 @@ [PcdsFixedAtBuild, PcdsDynamic, PcdsDynamicEx,
>> PcdsPatchableInModule]
>>     # @Expression 0x80000001 |
>> gPcAtChipsetPkgTokenSpaceGuid.PcdMaximalValidYear <
>> gPcAtChipsetPkgTokenSpaceGuid.PcdMinimalValidYear + 100
>>    
>> gPcAtChipsetPkgTokenSpaceGuid.PcdMaximalValidYear|2097|UINT16|0x0000000E
>>   +  ## Specifies RTC Index Register address in MMIO space.
>> +  # @Prompt RTC Index Register address
>> + 
>> gPcAtChipsetPkgTokenSpaceGuid.PcdRtcIndexRegister64|0x0|UINT64|0x00000022
>> +
>> +  ## Specifies RTC Target Register address in MMIO space.
>> +  # @Prompt RTC Target Register address
>> + 
>> gPcAtChipsetPkgTokenSpaceGuid.PcdRtcTargetRegister64|0x0|UINT64|0x00000023
>>
>> +
>>   [PcdsFixedAtBuild, PcdsPatchableInModule]
>>     ## Defines the ACPI register set base address.
>>     #  The invalid 0xFFFF is as its default value. It must be
>> configured to the real value.
>> diff --git a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c
>> b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c
>> index
>> 52af17941786ef81c3911512ee64551724e67209..64f36f6fbbd1b03967bd1a1290d108d5b0f294fa
>> 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 +11,9 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
>>     #include "PcRtc.h"
>>   +extern UINTN  mRtcIndexRegister;
>> +extern UINTN  mRtcTargetRegister;
>> +
>>   //
>>   // Days of month.
>>   //
>> @@ -54,38 +58,132 @@ IsWithinOneDay (
>>     );
>>     /**
>> +  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.
>> +
>> +  @return The data of UINT8 type read from RTC.
>> +**/
>> +STATIC
>> +UINT8
>> +IoRtcRead (
>> +  IN  UINTN Address
>> +  )
>> +{
>> +  IoWrite8 (
>> +    PcdGet8 (PcdRtcIndexRegister),
>> +    (UINT8)(Address | (UINT8)(IoRead8 (PcdGet8 (PcdRtcIndexRegister))
>> & 0x80))
>> +    );
>> +  return IoRead8 (PcdGet8 (PcdRtcTargetRegister));
>> +}
>> +
>> +/**
>> +  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.
>> +
>> +**/
>> +STATIC
>> +VOID
>> +IoRtcWrite (
>> +  IN  UINTN   Address,
>> +  IN  UINT8   Data
>> +  )
>> +{
>> +  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  UINTN Address
>> +  )
>> +{
>> +  MmioWrite8 (
>> +    mRtcIndexRegister,
>> +    (UINT8)(Address | (UINT8)(MmioRead8 (mRtcIndexRegister) & 0x80))
>> +    );
>> +  return MmioRead8 (mRtcTargetRegister);
>> +}
>> +
>> +/**
>> +  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  UINTN   Address,
>> +  IN  UINT8   Data
>> +  )
>> +{
>> +  MmioWrite8 (
>> +    mRtcIndexRegister,
>> +    (UINT8)(Address | (UINT8)(MmioRead8 (mRtcIndexRegister) & 0x80))
>> +    );
>> +  MmioWrite8 (mRtcTargetRegister, Data);
>> +}
>> +
>> +/**
>>     Read RTC content through its registers.
>>   -  @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 (
>> -  IN  UINT8 Address
>> +  IN  UINTN Address
>>     )
>>   {
>> -  IoWrite8 (PcdGet8 (PcdRtcIndexRegister), (UINT8) (Address | (UINT8)
>> (IoRead8 (PcdGet8 (PcdRtcIndexRegister)) & 0x80)));
>> -  return IoRead8 (PcdGet8 (PcdRtcTargetRegister));
>> +  if (FeaturePcdGet (PcdRtcUseMmio)) {
>> +    return MmioRtcRead (Address);
>> +  }
>> +
>> +  return IoRtcRead (Address);
>>   }
>>     /**
>>     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.
>> +  @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 (
>> -  IN  UINT8   Address,
>> +  IN  UINTN   Address,
>>     IN  UINT8   Data
>>     )
>>   {
>> -  IoWrite8 (PcdGet8 (PcdRtcIndexRegister), (UINT8) (Address | (UINT8)
>> (IoRead8 (PcdGet8 (PcdRtcIndexRegister)) & 0x80)));
>> -  IoWrite8 (PcdGet8 (PcdRtcTargetRegister), Data);
>> +  if (FeaturePcdGet (PcdRtcUseMmio)) {
>> +    MmioRtcWrite (Address, Data);
>> +  } else {
>> +    IoRtcWrite (Address, Data);
>> +  }
>>   }
>>     /**
>> diff --git a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtcEntry.c
>> b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtcEntry.c
>> index
>> ccda6331373bfe4069b0a59495b5e5cc731c8fc8..606b88adafb7ef5d81e32e212794a5ccae9d0443
>> 100644
>> --- a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtcEntry.c
>> +++ b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtcEntry.c
>> @@ -2,16 +2,23 @@
>>     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;
>> +
>> +UINTN                  mRtcIndexRegister;
>> +UINTN                  mRtcTargetRegister;
>> +
>>   /**
>>     Returns the current time and date information, and the
>> time-keeping capabilities
>>     of the hardware platform.
>> @@ -106,6 +113,30 @@ 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**)&mRtcIndexRegister);
>> +  EfiConvertPointer (0x0, (VOID**)&mRtcTargetRegister);
>> +}
>> +
>> +/**
>>     The user Entry Point for PcRTC module.
>>       This is the entry point for PcRTC module. It installs the UEFI
>> runtime service
>> @@ -131,6 +162,11 @@ InitializePcRtc (
>>     EfiInitializeLock (&mModuleGlobal.RtcLock, TPL_CALLBACK);
>>     mModuleGlobal.CenturyRtcAddress = GetCenturyRtcAddress ();
>>   +  if (FeaturePcdGet (PcdRtcUseMmio)) {
>> +    mRtcIndexRegister = (UINTN)PcdGet64 (PcdRtcIndexRegister64);
>> +    mRtcTargetRegister = (UINTN)PcdGet64 (PcdRtcTargetRegister64);
>> +  }
>> +
>>     Status = PcRtcInit (&mModuleGlobal);
>>     ASSERT_EFI_ERROR (Status);
>>   @@ -165,7 +201,23 @@ InitializePcRtc (
>>                     NULL,
>>                     NULL
>>                     );
>> -  ASSERT_EFI_ERROR (Status);
>> +  if (EFI_ERROR (Status)) {
>> +    ASSERT_EFI_ERROR (Status);
>> +    return Status;
>> +  }
>> +
>> +  if (FeaturePcdGet (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
>> c73ee98105e510f9e4e23c1a6c1e5c505325d2c9..0d8eca28b65954b073a72fc4fe5ad6247320e79d
>> 100644
>> ---
>> a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcatRealTimeClockRuntimeDxe.inf
>>
>> +++
>> b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcatRealTimeClockRuntimeDxe.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 - 2020, ARM Limited. All rights reserved.<BR>
>>   #
>>   # SPDX-License-Identifier: BSD-2-Clause-Patent
>>   #
>> @@ -61,6 +62,11 @@ [Guids]
>>     ## SOMETIMES_CONSUMES ## SystemTable
>>     gEfiAcpiTableGuid
>>   +  gEfiEventVirtualAddressChangeGuid
>> +
>> +[FeaturePcd]
>> +  gPcAtChipsetPkgTokenSpaceGuid.PcdRtcUseMmio                   ##
>> CONSUMES
>> +
>>   [FixedPcd]
>>     gPcAtChipsetPkgTokenSpaceGuid.PcdInitialValueRtcRegisterA     ##
>> CONSUMES
>>     gPcAtChipsetPkgTokenSpaceGuid.PcdInitialValueRtcRegisterB     ##
>> CONSUMES
>> @@ -72,6 +78,8 @@ [Pcd]
>>     gPcAtChipsetPkgTokenSpaceGuid.PcdMaximalValidYear             ##
>> CONSUMES
>>     gPcAtChipsetPkgTokenSpaceGuid.PcdRtcIndexRegister             ##
>> CONSUMES
>>     gPcAtChipsetPkgTokenSpaceGuid.PcdRtcTargetRegister            ##
>> CONSUMES
>> +  gPcAtChipsetPkgTokenSpaceGuid.PcdRtcIndexRegister64           ##
>> CONSUMES
>> +  gPcAtChipsetPkgTokenSpaceGuid.PcdRtcTargetRegister64          ##
>> CONSUMES
>>     [Depex]
>>     gEfiVariableArchProtocolGuid AND gEfiVariableWriteArchProtocolGuid
>>
>