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/** @file
Timer Library functions built upon local APIC on IA32/x64.
@bug Should use PCD to retrieve all the constants including index of
the IA32_APIC_BASE MSR, the offsets of InitialCount, CorrentCount
and DivideConfiguration.
Copyright (c) 2006, Intel Corporation<BR>
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.
Module Name: x86TimerLib.c
**/
static
UINTN
EFIAPI
DelayWorker (
IN UINT64 NDelay
)
{
UINT64 Ticks;
Ticks = GetPerformanceCounter ();
Ticks -= DivU64x32 (
MultU64x64 (
GetPerformanceCounterProperties (NULL, NULL),
NDelay
),
1000000000u
);
while (Ticks <= GetPerformanceCounter ());
return (UINTN)Ticks;
}
/**
Stalls the CPU for at least the given number of microseconds.
Stalls the CPU for the number of microseconds specified by MicroSeconds.
@param MicroSeconds The minimum number of microseconds to delay.
@return Return value depends on implementation.
**/
UINTN
EFIAPI
MicroSecondDelay (
IN UINTN MicroSeconds
)
{
return DelayWorker (MicroSeconds * 1000ull);
}
/**
Stalls the CPU for at least the given number of nanoseconds.
Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
@param NanoSeconds The minimum number of nanoseconds to delay.
@return Return value depends on implementation.
**/
UINTN
EFIAPI
NanoSecondDelay (
IN UINTN NanoSeconds
)
{
return DelayWorker (NanoSeconds);
}
static
UINTN
EFIAPI
GetApicBase (
VOID
)
{
return (UINTN)AsmMsrBitFieldRead64 (27, 12, 35) << 12;
}
/**
Retrieves the current value of a 64-bit free running performance counter.
Retrieves the current value of a 64-bit free running performance counter. The
counter can either count up by 1 or count down by 1. If the physical
performance counter counts by a larger increment, then the counter values
must be translated. The properties of the counter can be retrieved from
GetPerformanceCounterProperties().
@return The current value of the free running performance counter.
**/
UINT64
EFIAPI
GetPerformanceCounter (
VOID
)
{
return MmioRead32 (GetApicBase () + 0x390);
}
/**
Retrieves the 64-bit frequency in Hz and the range of performance counter
values.
If StartValue is not NULL, then the value that the performance counter starts
with immediately after is it rolls over is returned in StartValue. If
EndValue is not NULL, then the value that the performance counter end with
immediately before it rolls over is returned in EndValue. The 64-bit
frequency of the performance counter in Hz is always returned. If StartValue
is less than EndValue, then the performance counter counts up. If StartValue
is greater than EndValue, then the performance counter counts down. For
example, a 64-bit free running counter that counts up would have a StartValue
of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
@param StartValue The value the performance counter starts with when it
rolls over.
@param EndValue The value that the performance counter ends with before
it rolls over.
@return The frequency in Hz.
**/
UINT64
EFIAPI
GetPerformanceCounterProperties (
IN UINT64 *StartValue,
IN UINT64 *EndValue
)
{
static const UINT32 mFrequencies[] = {
100000000,
133000000,
200000000,
166000000
};
static const UINT8 mDivisor[] = {
0x02, 0x04, 0x08, 0x10,
0x02, 0x04, 0x08, 0x10,
0x20, 0x40, 0x80, 0x01,
0x20, 0x40, 0x80, 0x01
};
UINTN ApicBase;
ApicBase = GetApicBase ();
if (StartValue != NULL) {
*StartValue = MmioRead32 (ApicBase + 0x380);
}
if (EndValue != NULL) {
*EndValue = 0;
}
return mFrequencies[AsmMsrBitFieldRead32 (44, 16, 18)] /
mDivisor[MmioBitFieldRead32 (ApicBase + 0x3e0, 0, 3)];
}
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