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/** @file
Timer Library functions built upon local APIC on IA32/x64.
Copyright (c) 2006 - 2008, 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.
**/
#include <Base.h>
#include <Library/TimerLib.h>
#include <Library/BaseLib.h>
#include <Library/IoLib.h>
#include <Library/PcdLib.h>
#define APIC_LVTERR 0x370
#define APIC_TMICT 0x380
#define APIC_TMCCT 0x390
#define APIC_TDCR 0x3e0
//
// The following array is used in calculating the frequency of local APIC
// timer. Refer to IA-32 developers' manual for more details.
//
GLOBAL_REMOVE_IF_UNREFERENCED
CONST UINT8 mTimerLibLocalApicDivisor[] = {
0x02, 0x04, 0x08, 0x10,
0x02, 0x04, 0x08, 0x10,
0x20, 0x40, 0x80, 0x01,
0x20, 0x40, 0x80, 0x01
};
/**
Internal function to retrieve the base address of local APIC.
@return The base address of local APIC
**/
UINTN
EFIAPI
InternalX86GetApicBase (
VOID
)
{
return (UINTN)AsmMsrBitFieldRead64 (27, 12, 35) << 12;
}
/**
Internal function to return the frequency of the local APIC timer.
@param ApicBase The base address of memory mapped registers of local APIC.
@return The frequency of the timer in Hz.
**/
UINT32
EFIAPI
InternalX86GetTimerFrequency (
IN UINTN ApicBase
)
{
return
PcdGet32(PcdFSBClock) /
mTimerLibLocalApicDivisor[MmioBitFieldRead32 (ApicBase + APIC_TDCR, 0, 3)];
}
/**
Internal function to read the current tick counter of local APIC.
@param ApicBase The base address of memory mapped registers of local APIC.
@return The tick counter read.
**/
INT32
EFIAPI
InternalX86GetTimerTick (
IN UINTN ApicBase
)
{
return MmioRead32 (ApicBase + APIC_TMCCT);
}
/**
Stalls the CPU for at least the given number of ticks.
Stalls the CPU for at least the given number of ticks. It's invoked by
MicroSecondDelay() and NanoSecondDelay().
@param ApicBase The base address of memory mapped registers of local APIC.
@param Delay A period of time to delay in ticks.
**/
VOID
EFIAPI
InternalX86Delay (
IN UINTN ApicBase,
IN UINT32 Delay
)
{
INT32 Ticks;
//
// The target timer count is calculated here
//
Ticks = InternalX86GetTimerTick (ApicBase) - Delay;
//
// Wait until time out
// Delay > 2^31 could not be handled by this function
// Timer wrap-arounds are handled correctly by this function
//
while (InternalX86GetTimerTick (ApicBase) - Ticks >= 0);
}
/**
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 The value of MicroSeconds inputted.
**/
UINTN
EFIAPI
MicroSecondDelay (
IN UINTN MicroSeconds
)
{
UINTN ApicBase;
ApicBase = InternalX86GetApicBase ();
InternalX86Delay (
ApicBase,
(UINT32)DivU64x32 (
MultU64x64 (
InternalX86GetTimerFrequency (ApicBase),
MicroSeconds
),
1000000u
)
);
return MicroSeconds;
}
/**
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 The value of NanoSeconds inputted.
**/
UINTN
EFIAPI
NanoSecondDelay (
IN UINTN NanoSeconds
)
{
UINTN ApicBase;
ApicBase = InternalX86GetApicBase ();
InternalX86Delay (
ApicBase,
(UINT32)DivU64x32 (
MultU64x64 (
InternalX86GetTimerFrequency (ApicBase),
NanoSeconds
),
1000000000u
)
);
return NanoSeconds;
}
/**
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 (UINT64)(UINT32)InternalX86GetTimerTick (InternalX86GetApicBase ());
}
/**
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 (
OUT UINT64 *StartValue, OPTIONAL
OUT UINT64 *EndValue OPTIONAL
)
{
UINTN ApicBase;
ApicBase = InternalX86GetApicBase ();
if (StartValue != NULL) {
*StartValue = MmioRead32 (ApicBase + APIC_TMICT);
}
if (EndValue != NULL) {
*EndValue = 0;
}
return (UINT64) InternalX86GetTimerFrequency (ApicBase);
}
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