On Fri, 20 Oct 2023 at 14:17, Laszlo Ersek <ler...@redhat.com> wrote:
>
> RealTimeClockLib instances are consumed by edk2's
> EmbeddedPkg/RealTimeClockRuntimeDxe driver. In its entry point function
> InitializeRealTimeClock(), the driver:
>
> (1) calls LibRtcInitialize(),
>
> (2) sets the GetTime(), SetTime(), GetWakeupTime() and SetWakeupTime()
> runtime services to its own similarly-named functions -- where those
> functions wrap the corresponding RealTimeClockLib APIs,
>
> (3) installs EFI_REAL_TIME_CLOCK_ARCH_PROTOCOL with a NULL protocol
> interface.
>
> Steps (2) and (3) conform to PI v1.8 sections II-9.7.2.4 through
> II-9.7.2.7.
>
> However, this means that LibRtcInitialize() (of any RealTimeClockLib
> instance) should not itself (a) set the GetTime(), SetTime(),
> GetWakeupTime() and SetWakeupTime() runtime services, nor (b) install
> EFI_REAL_TIME_CLOCK_ARCH_PROTOCOL. The runtime service pointers will be
> overwritten in step (2) anyway, and step (3) will uselessly install a
> second (NULL-interface) EFI_REAL_TIME_CLOCK_ARCH_PROTOCOL instance in the
> protocol database. (The protocol only serves to notify the DXE Foundation
> about said runtime services being available.)
>
> Clean up ArmPlatformPkg/PL031RealTimeClockLib accordingly (it only has
> code that's redundant for step (3); it does not try to set "gRT" fields).
>
> (Note that the lib instance INF file already does not list
> gEfiRealTimeClockArchProtocolGuid.)
>
> Tested with ArmVirtQemu.
>
> Cc: Ard Biesheuvel <ardb+tianoc...@kernel.org>
> Cc: Leif Lindholm <quic_llind...@quicinc.com>
> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=4565
> Signed-off-by: Laszlo Ersek <ler...@redhat.com>
> ---
>
> Notes:
> context:-W
>
> ArmPlatformPkg/Library/PL031RealTimeClockLib/PL031RealTimeClockLib.c | 13
> -------------
> 1 file changed, 13 deletions(-)
>
Acked-by: Ard Biesheuvel <a...@kernel.org>
Thanks a lot for cleaning up this mess.
> diff --git
> a/ArmPlatformPkg/Library/PL031RealTimeClockLib/PL031RealTimeClockLib.c
> b/ArmPlatformPkg/Library/PL031RealTimeClockLib/PL031RealTimeClockLib.c
> index 9e852696d2fd..1896f9d16d3b 100644
> --- a/ArmPlatformPkg/Library/PL031RealTimeClockLib/PL031RealTimeClockLib.c
> +++ b/ArmPlatformPkg/Library/PL031RealTimeClockLib/PL031RealTimeClockLib.c
> @@ -1,34 +1,32 @@
> /** @file
> Implement EFI RealTimeClock runtime services via RTC Lib.
>
> Copyright (c) 2008 - 2010, Apple Inc. All rights reserved.<BR>
> Copyright (c) 2011 - 2020, Arm Limited. All rights reserved.<BR>
> Copyright (c) 2019, Linaro Ltd. All rights reserved.<BR>
>
> SPDX-License-Identifier: BSD-2-Clause-Patent
>
> **/
>
> #include <PiDxe.h>
>
> #include <Guid/EventGroup.h>
> #include <Guid/GlobalVariable.h>
>
> #include <Library/BaseLib.h>
> #include <Library/DebugLib.h>
> #include <Library/DxeServicesTableLib.h>
> #include <Library/IoLib.h>
> #include <Library/MemoryAllocationLib.h>
> #include <Library/PcdLib.h>
> #include <Library/RealTimeClockLib.h>
> #include <Library/TimeBaseLib.h>
> #include <Library/UefiBootServicesTableLib.h>
> #include <Library/UefiLib.h>
> #include <Library/UefiRuntimeServicesTableLib.h>
> #include <Library/UefiRuntimeLib.h>
>
> -#include <Protocol/RealTimeClock.h>
> -
> #include "PL031RealTimeClock.h"
>
> STATIC BOOLEAN mPL031Initialized = FALSE;
> @@ -307,52 +305,41 @@ EFIAPI
> LibRtcInitialize (
> IN EFI_HANDLE ImageHandle,
> IN EFI_SYSTEM_TABLE *SystemTable
> )
> {
> EFI_STATUS Status;
> - EFI_HANDLE Handle;
>
> // Initialize RTC Base Address
> mPL031RtcBase = PcdGet32 (PcdPL031RtcBase);
>
> // Declare the controller as EFI_MEMORY_RUNTIME
> Status = gDS->AddMemorySpace (
> EfiGcdMemoryTypeMemoryMappedIo,
> mPL031RtcBase,
> SIZE_4KB,
> EFI_MEMORY_UC | EFI_MEMORY_RUNTIME
> );
> if (EFI_ERROR (Status)) {
> return Status;
> }
>
> Status = gDS->SetMemorySpaceAttributes (mPL031RtcBase, SIZE_4KB,
> EFI_MEMORY_UC | EFI_MEMORY_RUNTIME);
> if (EFI_ERROR (Status)) {
> return Status;
> }
>
> - // Install the protocol
> - Handle = NULL;
> - Status = gBS->InstallMultipleProtocolInterfaces (
> - &Handle,
> - &gEfiRealTimeClockArchProtocolGuid,
> - NULL,
> - NULL
> - );
> - ASSERT_EFI_ERROR (Status);
> -
> //
> // Register for the virtual address change event
> //
> Status = gBS->CreateEventEx (
> EVT_NOTIFY_SIGNAL,
> TPL_NOTIFY,
> VirtualNotifyEvent,
> NULL,
> &gEfiEventVirtualAddressChangeGuid,
> &mRtcVirtualAddrChangeEvent
> );
> ASSERT_EFI_ERROR (Status);
>
> return Status;
> }
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