MdePkg/Include/Protocol/Timestamp.h File Reference


Data Structures

struct  EFI_TIMESTAMP_PROPERTIES
struct  _EFI_TIMESTAMP_PROTOCOL

Defines

#define EFI_TIMESTAMP_PROTOCOL_GUID   { 0xafbfde41, 0x2e6e, 0x4262, {0xba, 0x65, 0x62, 0xb9, 0x23, 0x6e, 0x54, 0x95 } }

Typedefs

typedef struct
_EFI_TIMESTAMP_PROTOCOL 
EFI_TIMESTAMP_PROTOCOL
typedef UINT64(EFIAPI * TIMESTAMP_GET )(VOID)
typedef EFI_STATUS(EFIAPI * TIMESTAMP_GET_PROPERTIES )(OUT EFI_TIMESTAMP_PROPERTIES *Properties)

Variables

EFI_GUID gEfiTimestampProtocolGuid

Detailed Description

EFI Timestamp Protocol as defined in UEFI2.4 Specification. Used to provide a platform independent interface for retrieving a high resolution timestamp counter.

Copyright (c) 2013, Intel Corporation. All rights reserved.
This program and the accompanying materials are licensed and made available under the terms and conditions of the BSD License which accompanies this distribution. The full text of the license may be found at http://opensource.org/licenses/bsd-license.php

THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

Revision Reference:
This Protocol is introduced in UEFI Specification 2.4

Define Documentation

#define EFI_TIMESTAMP_PROTOCOL_GUID   { 0xafbfde41, 0x2e6e, 0x4262, {0xba, 0x65, 0x62, 0xb9, 0x23, 0x6e, 0x54, 0x95 } }


Typedef Documentation

Declare forward reference for the Time Stamp Protocol

typedef UINT64(EFIAPI * TIMESTAMP_GET)(VOID)

Retrieves the current value of a 64-bit free running timestamp counter.

The counter shall count up in proportion to the amount of time that has passed. The counter value will always roll over to zero. The properties of the counter can be retrieved from GetProperties(). The caller should be prepared for the function to return the same value twice across successive calls. The counter value will not go backwards other than when wrapping, as defined by EndValue in GetProperties(). The frequency of the returned timestamp counter value must remain constant. Power management operations that affect clocking must not change the returned counter frequency. The quantization of counter value updates may vary as long as the value reflecting time passed remains consistent.

Parameters:
None. 
Return values:
The current value of the free running timestamp counter.

typedef EFI_STATUS(EFIAPI * TIMESTAMP_GET_PROPERTIES)(OUT EFI_TIMESTAMP_PROPERTIES *Properties)

Obtains timestamp counter properties including frequency and value limits.

Parameters:
[out] Properties The properties of the timestamp counter.
Return values:
EFI_SUCCESS The properties were successfully retrieved.
EFI_DEVICE_ERROR An error occurred trying to retrieve the properties of the timestamp counter subsystem. Properties is not pedated.
EFI_INVALID_PARAMETER Properties is NULL.


Variable Documentation


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