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