Metronome.c File Reference

#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>

Go to the source code of this file.

Functions
EFI_STATUS EFIAPI	WaitForTick (IN EFI_METRONOME_ARCH_PROTOCOL *This, IN UINT32 TickNumber)
EFI_STATUS EFIAPI	MetronomeInitialize (IN EFI_HANDLE ImageHandle, IN EFI_SYSTEM_TABLE *SystemTable)

Variables
EFI_METRONOME_ARCH_PROTOCOL	gMetronome
EFI_HANDLE	gMetronomeHandle = NULL

Detailed Description

Copyright (c) 2008 - 2009, Apple Inc. All rights reserved.
Copyright (c) 2013, ARM Ltd. All rights reserved.

SPDX-License-Identifier: BSD-2-Clause-Patent

Definition in file Metronome.c.

Function Documentation

MetronomeInitialize()

EFI_STATUS EFIAPI MetronomeInitialize	(	IN EFI_HANDLE	ImageHandle,
		IN EFI_SYSTEM_TABLE *	SystemTable
	)

Initialize the state information for the CPU Architectural Protocol

Parameters

ImageHandle	of the loaded driver
SystemTable	Pointer to the System Table

Return values

EFI_SUCCESS	Protocol registered
EFI_OUT_OF_RESOURCES	Cannot allocate protocol data structure
EFI_DEVICE_ERROR	Hardware problems

Definition at line 109 of file Metronome.c.

WaitForTick()

EFI_STATUS EFIAPI WaitForTick	(	IN EFI_METRONOME_ARCH_PROTOCOL *	This,
		IN UINT32	TickNumber
	)

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.

Parameters

This	The EFI_METRONOME_ARCH_PROTOCOL instance.
TickNumber	Number of ticks to wait.

Return values

EFI_SUCCESS	The wait for the number of ticks specified by TickNumber succeeded.
EFI_TIMEOUT	A timeout occurred waiting for the specified number of ticks.

Definition at line 80 of file Metronome.c.

Variable Documentation

gMetronome

EFI_METRONOME_ARCH_PROTOCOL gMetronome

Initial value:

= {
  WaitForTick,
  FixedPcdGet32 (PcdMetronomeTickPeriod)
}

Interface structure for the Metronome Architectural Protocol.

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.

Parameters

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.
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.

Definition at line 51 of file Metronome.c.

gMetronomeHandle

EFI_HANDLE gMetronomeHandle = NULL

Definition at line 94 of file Metronome.c.