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EmbeddedPkg/Metronome.c: Fix delay computed by WaitForTick() function.

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Before the tick period used by the Metronome was hardcoded to 100.
This has been changed since but WaitForTick() function was still relying
on this hardcoded value to compute the number of milliseconds to stall
the CPU.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Olivier Martin <olivier.martin@arm.com>



git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@14172 6f19259b-4bc3-4df7-8a09-765794883524
This commit is contained in:
oliviermartin 2013-03-12 00:38:15 +00:00
parent 05c7d5f615
commit c9bf2a9e2d
1 changed files with 53 additions and 47 deletions
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74
EmbeddedPkg/MetronomeDxe/Metronome.c
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@ -1,7 +1,7 @@
/** @file
Copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
Copyright (c) 2012, ARM Ltd. All rights reserved.
Copyright (c) 2013, ARM Ltd. All rights reserved.
This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
@ -25,6 +25,40 @@
#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 be at least 10 uS, and 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)
};
/**
@ -57,43 +91,15 @@ WaitForTick (
)
{
//
// Fill me in
// 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 (10 * TickNumber);
return EFI_UNSUPPORTED;
MicroSecondDelay (TickNumber * gMetronome.TickPeriod / 10);
return EFI_SUCCESS;
}
/**
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 be at least 10 uS, and 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)
};
EFI_HANDLE gMetronomeHandle = NULL;