Timer.h File Reference

Data Structures
struct	_EFI_TIMER_ARCH_PROTOCOL

Macros
#define	EFI_TIMER_ARCH_PROTOCOL_GUID   { 0x26baccb3, 0x6f42, 0x11d4, {0xbc, 0xe7, 0x0, 0x80, 0xc7, 0x3c, 0x88, 0x81 } }

Typedefs
typedef struct _EFI_TIMER_ARCH_PROTOCOL	EFI_TIMER_ARCH_PROTOCOL
typedef VOID(EFIAPI *	EFI_TIMER_NOTIFY )(IN UINT64 Time)
typedef EFI_STATUS(EFIAPI *	EFI_TIMER_REGISTER_HANDLER )(IN EFI_TIMER_ARCH_PROTOCOL *This, IN EFI_TIMER_NOTIFY NotifyFunction)
typedef EFI_STATUS(EFIAPI *	EFI_TIMER_SET_TIMER_PERIOD )(IN EFI_TIMER_ARCH_PROTOCOL *This, IN UINT64 TimerPeriod)
typedef EFI_STATUS(EFIAPI *	EFI_TIMER_GET_TIMER_PERIOD )(IN EFI_TIMER_ARCH_PROTOCOL *This, OUT UINT64 *TimerPeriod)
typedef EFI_STATUS(EFIAPI *	EFI_TIMER_GENERATE_SOFT_INTERRUPT )(IN EFI_TIMER_ARCH_PROTOCOL *This)

Variables
EFI_GUID	gEfiTimerArchProtocolGuid

Detailed Description

Timer Architectural Protocol as defined in PI Specification VOLUME 2 DXE

This code is used to provide the timer tick for the DXE core.

Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.
SPDX-License-Identifier: BSD-2-Clause-Patent

Macro Definition Documentation

#define EFI_TIMER_ARCH_PROTOCOL_GUID   { 0x26baccb3, 0x6f42, 0x11d4, {0xbc, 0xe7, 0x0, 0x80, 0xc7, 0x3c, 0x88, 0x81 } }

Global ID for the Timer Architectural Protocol

Typedef Documentation

typedef struct _EFI_TIMER_ARCH_PROTOCOL EFI_TIMER_ARCH_PROTOCOL

Declare forward reference for the Timer Architectural Protocol

typedef EFI_STATUS(EFIAPI * EFI_TIMER_GENERATE_SOFT_INTERRUPT)(IN EFI_TIMER_ARCH_PROTOCOL *This)

This function generates a soft timer interrupt. If the platform does not support soft timer interrupts, then EFI_UNSUPPORTED is returned. Otherwise, EFI_SUCCESS is returned. If a handler has been registered through the EFI_TIMER_ARCH_PROTOCOL.RegisterHandler() service, then a soft timer interrupt will be generated. If the timer interrupt is enabled when this service is called, then the registered handler will be invoked. The registered handler should not be able to distinguish a hardware-generated timer interrupt from a software-generated timer interrupt.

Parameters

This	The EFI_TIMER_ARCH_PROTOCOL instance.

Return values

EFI_SUCCESS	The soft timer interrupt was generated.
EFI_UNSUPPORTED	The platform does not support the generation of soft timer interrupts.

typedef EFI_STATUS(EFIAPI * EFI_TIMER_GET_TIMER_PERIOD)(IN EFI_TIMER_ARCH_PROTOCOL *This, OUT UINT64 *TimerPeriod)

This function retrieves the period of timer interrupts in 100 ns units, returns that value in TimerPeriod, and returns EFI_SUCCESS. If TimerPeriod is NULL, then EFI_INVALID_PARAMETER is returned. If a TimerPeriod of 0 is returned, then the timer is currently disabled.

Parameters

This	The EFI_TIMER_ARCH_PROTOCOL instance.
TimerPeriod	A pointer to the timer period to retrieve in 100 ns units. If 0 is returned, then the timer is currently disabled.

Return values

EFI_SUCCESS	The timer period was returned in TimerPeriod.
EFI_INVALID_PARAMETER	TimerPeriod is NULL.

typedef VOID(EFIAPI * EFI_TIMER_NOTIFY)(IN UINT64 Time)

This function of this type is called when a timer interrupt fires. This function executes at TPL_HIGH_LEVEL. The DXE Core will register a function of this type to be called for the timer interrupt, so it can know how much time has passed. This information is used to signal timer based events.

Parameters

Time	Time since the last timer interrupt in 100 ns units. This will typically be TimerPeriod, but if a timer interrupt is missed, and the EFI_TIMER_ARCH_PROTOCOL driver can detect missed interrupts, then Time will contain the actual amount of time since the last interrupt.

None.

typedef EFI_STATUS(EFIAPI * EFI_TIMER_REGISTER_HANDLER)(IN EFI_TIMER_ARCH_PROTOCOL *This, IN EFI_TIMER_NOTIFY NotifyFunction)

This function registers the handler NotifyFunction so it is called every time the timer interrupt fires. It also passes the amount of time since the last handler call to the NotifyFunction. If NotifyFunction is NULL, then the handler is unregistered. If the handler is registered, then EFI_SUCCESS is returned. If the CPU does not support registering a timer interrupt handler, then EFI_UNSUPPORTED is returned. If an attempt is made to register a handler when a handler is already registered, then EFI_ALREADY_STARTED is returned. If an attempt is made to unregister a handler when a handler is not registered, then EFI_INVALID_PARAMETER is returned. If an error occurs attempting to register the NotifyFunction with the timer interrupt, then EFI_DEVICE_ERROR is returned.

Parameters

This	The EFI_TIMER_ARCH_PROTOCOL instance.
NotifyFunction	The function to call when a timer interrupt fires. This function executes at TPL_HIGH_LEVEL. The DXE Core will register a handler for the timer interrupt, so it can know how much time has passed. This information is used to signal timer based events. NULL will unregister the handler.

Return values

EFI_SUCCESS	The timer handler was registered.
EFI_UNSUPPORTED	The platform does not support timer interrupts.
EFI_ALREADY_STARTED	NotifyFunction is not NULL, and a handler is already registered.
EFI_INVALID_PARAMETER	NotifyFunction is NULL, and a handler was not previously registered.
EFI_DEVICE_ERROR	The timer handler could not be registered.

typedef EFI_STATUS(EFIAPI * EFI_TIMER_SET_TIMER_PERIOD)(IN EFI_TIMER_ARCH_PROTOCOL *This, IN UINT64 TimerPeriod)

This function adjusts the period of timer interrupts to the value specified by TimerPeriod. If the timer period is updated, then the selected timer period is stored in EFI_TIMER.TimerPeriod, and EFI_SUCCESS is returned. If the timer hardware is not programmable, then EFI_UNSUPPORTED is returned. If an error occurs while attempting to update the timer period, then the timer hardware will be put back in its state prior to this call, and EFI_DEVICE_ERROR is returned. If TimerPeriod is 0, then the timer interrupt is disabled. This is not the same as disabling the CPU's interrupts. Instead, it must either turn off the timer hardware, or it must adjust the interrupt controller so that a CPU interrupt is not generated when the timer interrupt fires.

Parameters

This	The EFI_TIMER_ARCH_PROTOCOL instance.
TimerPeriod	The rate to program the timer interrupt in 100 nS units. If the timer hardware is not programmable, then EFI_UNSUPPORTED is returned. If the timer is programmable, then the timer period will be rounded up to the nearest timer period that is supported by the timer hardware. If TimerPeriod is set to 0, then the timer interrupts will be disabled.

Return values

EFI_SUCCESS	The timer period was changed.
EFI_UNSUPPORTED	The platform cannot change the period of the timer interrupt.
EFI_DEVICE_ERROR	The timer period could not be changed due to a device error.

Variable Documentation

EFI_GUID gEfiTimerArchProtocolGuid