mirror of https://github.com/acidanthera/audk.git
130 lines
4.1 KiB
C
130 lines
4.1 KiB
C
/** @file
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Copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
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Copyright (c) 2013, ARM Ltd. All rights reserved.
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SPDX-License-Identifier: BSD-2-Clause-Patent
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**/
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#include <PiDxe.h>
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#include <Library/BaseLib.h>
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#include <Library/DebugLib.h>
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#include <Library/BaseMemoryLib.h>
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#include <Library/UefiBootServicesTableLib.h>
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#include <Library/UefiLib.h>
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#include <Library/PcdLib.h>
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#include <Library/TimerLib.h>
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#include <Protocol/Metronome.h>
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EFI_STATUS
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EFIAPI
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WaitForTick (
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IN EFI_METRONOME_ARCH_PROTOCOL *This,
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IN UINT32 TickNumber
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);
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/**
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Interface structure for the Metronome Architectural Protocol.
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@par Protocol Description:
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This protocol provides access to a known time source in the platform to the
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core. The core uses this known time source to produce core services that
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require calibrated delays.
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@param WaitForTick
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Waits for a specified number of ticks from a known time source
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in the platform. The actual time passed between entry of this
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function and the first tick is between 0 and TickPeriod 100 nS
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units. If you want to guarantee that at least TickPeriod time
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has elapsed, wait for two ticks.
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@param TickPeriod
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The period of platform's known time source in 100 nS units.
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This value on any platform must not exceed 200 uS. The value in this field
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is a constant that must not be modified after the Metronome architectural
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protocol is installed. All consumers must treat this as a read-only field.
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**/
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EFI_METRONOME_ARCH_PROTOCOL gMetronome = {
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WaitForTick,
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FixedPcdGet32 (PcdMetronomeTickPeriod)
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};
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/**
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The WaitForTick() function waits for the number of ticks specified by
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TickNumber from a known time source in the platform. If TickNumber of
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ticks are detected, then EFI_SUCCESS is returned. The actual time passed
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between entry of this function and the first tick is between 0 and
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TickPeriod 100 nS units. If you want to guarantee that at least TickPeriod
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time has elapsed, wait for two ticks. This function waits for a hardware
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event to determine when a tick occurs. It is possible for interrupt
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processing, or exception processing to interrupt the execution of the
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WaitForTick() function. Depending on the hardware source for the ticks, it
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is possible for a tick to be missed. This function cannot guarantee that
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ticks will not be missed. If a timeout occurs waiting for the specified
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number of ticks, then EFI_TIMEOUT is returned.
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@param This The EFI_METRONOME_ARCH_PROTOCOL instance.
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@param TickNumber Number of ticks to wait.
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@retval EFI_SUCCESS The wait for the number of ticks specified by TickNumber
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succeeded.
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@retval EFI_TIMEOUT A timeout occurred waiting for the specified number of ticks.
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**/
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EFI_STATUS
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EFIAPI
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WaitForTick (
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IN EFI_METRONOME_ARCH_PROTOCOL *This,
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IN UINT32 TickNumber
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)
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{
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//
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// Compute how long to stall the CPU.
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// gMetronome.TickPeriod is in 100 ns units so it needs to be divided by 10
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// to get it in microseconds units.
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//
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MicroSecondDelay (TickNumber * gMetronome.TickPeriod / 10);
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return EFI_SUCCESS;
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}
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EFI_HANDLE gMetronomeHandle = NULL;
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/**
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Initialize the state information for the CPU Architectural Protocol
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@param ImageHandle of the loaded driver
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@param SystemTable Pointer to the System Table
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@retval EFI_SUCCESS Protocol registered
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@retval EFI_OUT_OF_RESOURCES Cannot allocate protocol data structure
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@retval EFI_DEVICE_ERROR Hardware problems
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**/
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EFI_STATUS
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EFIAPI
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MetronomeInitialize (
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IN EFI_HANDLE ImageHandle,
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IN EFI_SYSTEM_TABLE *SystemTable
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)
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{
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EFI_STATUS Status;
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//
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// Do any hardware init required to make WaitForTick () to work here.
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//
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Status = gBS->InstallMultipleProtocolInterfaces (
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&gMetronomeHandle,
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&gEfiMetronomeArchProtocolGuid,
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&gMetronome,
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NULL
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);
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ASSERT_EFI_ERROR (Status);
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return Status;
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}
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