mirror of https://github.com/acidanthera/audk.git
126 lines
4.7 KiB
C
126 lines
4.7 KiB
C
/** @file
|
|
Produces the Metronome Architectural Protocol on top of Timer Library.
|
|
|
|
This is a generic implementation of the Metronome Architectural Protocol that
|
|
layers on top of an instance of the Timer Library. The Timer Library provides
|
|
functions for nanosecond and microsecond delays. This generic implementation
|
|
produces a fixed TickPeriod of 1 100ns unit, and when the WaitForTick() service
|
|
is called, the number of ticks passed in is converted to either nanosecond or
|
|
microsecond units. If the number of ticks is small, then nanoseconds are used.
|
|
If the number of ticks is large, then microseconds are used. This prevents
|
|
overflows that could occur for long delays if only nanoseconds were used and also
|
|
provides the greatest accuracy for small delays.
|
|
|
|
Copyright (c) 2008, Intel Corporation. All rights reserved.<BR>
|
|
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.
|
|
|
|
**/
|
|
|
|
#include "Metronome.h"
|
|
|
|
//
|
|
// Handle for the Metronome Architectural Protocol instance produced by this driver
|
|
//
|
|
EFI_HANDLE mMetronomeHandle = NULL;
|
|
|
|
//
|
|
// The Metronome Architectural Protocol instance produced by this driver
|
|
//
|
|
EFI_METRONOME_ARCH_PROTOCOL mMetronome = {
|
|
WaitForTick,
|
|
1 // TickPeriod = 1*100 ns units
|
|
};
|
|
|
|
/**
|
|
Waits for the specified number of ticks.
|
|
|
|
This function implements EFI_METRONOME_ARCH_PROTOCOL.WaitForTick().
|
|
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
|
|
)
|
|
{
|
|
//
|
|
// Check the value of TickNumber, so a 32-bit overflow can be avoided
|
|
// when TickNumber of converted to nanosecond units
|
|
//
|
|
if (TickNumber < 10000000) {
|
|
//
|
|
// If TickNumber is small, then use NanoSecondDelay()
|
|
//
|
|
NanoSecondDelay (TickNumber * 100);
|
|
} else {
|
|
//
|
|
// If TickNumber is large, then use MicroSecondDelay()
|
|
//
|
|
MicroSecondDelay (TickNumber / 10);
|
|
}
|
|
return EFI_SUCCESS;
|
|
}
|
|
|
|
/**
|
|
The user Entry Point for module Metronome. The user code starts with this function.
|
|
|
|
@param[in] ImageHandle The firmware allocated handle for the EFI image.
|
|
@param[in] SystemTable A pointer to the EFI System Table.
|
|
|
|
@retval EFI_SUCCESS The entry point is executed successfully.
|
|
@retval other Some error occurs when executing this entry point.
|
|
|
|
**/
|
|
EFI_STATUS
|
|
EFIAPI
|
|
InstallMetronome (
|
|
IN EFI_HANDLE ImageHandle,
|
|
IN EFI_SYSTEM_TABLE *SystemTable
|
|
)
|
|
{
|
|
EFI_STATUS Status;
|
|
|
|
//
|
|
// Make sure the Metronome Architectural Protocol is not already installed in the system
|
|
//
|
|
ASSERT_PROTOCOL_ALREADY_INSTALLED (NULL, &gEfiMetronomeArchProtocolGuid);
|
|
|
|
//
|
|
// Install on a new handle
|
|
//
|
|
Status = gBS->InstallMultipleProtocolInterfaces (
|
|
&mMetronomeHandle,
|
|
&gEfiMetronomeArchProtocolGuid, &mMetronome,
|
|
NULL
|
|
);
|
|
ASSERT_EFI_ERROR (Status);
|
|
|
|
return Status;
|
|
}
|