/** @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)]; | |
} |