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/** @file
Generic ARM implementation of TimerLib.h
Copyright (c) 2011-2012, ARM Limited. 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/BaseLib.h>
#include <Library/TimerLib.h>
#include <Library/DebugLib.h>
#include <Library/PcdLib.h>
#include <Library/ArmV7ArchTimerLib.h>
#include <Chipset/ArmV7.h>
#define TICKS_PER_MICRO_SEC (PcdGet32 (PcdArmArchTimerFreqInHz)/1000000U)
RETURN_STATUS
EFIAPI
TimerConstructor (
VOID
)
{
// Check if the ARM Generic Timer Extension is implemented
if (ArmIsArchTimerImplemented ()) {
UINTN TimerFreq;
// Check if Architectural Timer frequency is valid number (should not be 0)
ASSERT (PcdGet32 (PcdArmArchTimerFreqInHz));
// Check if ticks/uS is not 0. The Architectural timer runs at constant
// frequency irrespective of CPU frequency. According to General Timer Ref
// manual lower bound of the frequency is in the range of 1-10MHz
ASSERT (TICKS_PER_MICRO_SEC);
// If the security extensions are not implemented set Timer Frequency
if ((ArmReadIdPfr1 () & 0xF0) == 0x0) {
ArmArchTimerSetTimerFreq (PcdGet32 (PcdArmArchTimerFreqInHz));
}
// Architectural Timer Frequency must be set in the Secure privileged(if secure extensions are supported) mode.
// If the reset value (0) is returned just ASSERT.
TimerFreq = ArmArchTimerGetTimerFreq ();
ASSERT (TimerFreq);
} else {
DEBUG ((EFI_D_ERROR, "ARM Architectural Timer is not available in the CPU, hence this library can not be used.\n"));
ASSERT (0);
}
return RETURN_SUCCESS;
}
/**
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
)
{
UINT64 TimerTicks64;
UINT64 SystemCounterVal;
// Calculate counter ticks that can represent requested delay
TimerTicks64 = MultU64x32 (MicroSeconds, TICKS_PER_MICRO_SEC);
// Read System Counter value
SystemCounterVal = ArmArchTimerGetSystemCount ();
TimerTicks64 += SystemCounterVal;
// Wait until delay count is expired.
while (SystemCounterVal < TimerTicks64) {
SystemCounterVal = ArmArchTimerGetSystemCount ();
}
return MicroSeconds;
}
/**
Stalls the CPU for at least the given number of nanoseconds.
Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
When the timer frequency is 1MHz, each tick corresponds to 1 microsecond.
Therefore, the nanosecond delay will be rounded up to the nearest 1 microsecond.
@param NanoSeconds The minimum number of nanoseconds to delay.
@return The value of NanoSeconds inputed.
**/
UINTN
EFIAPI
NanoSecondDelay (
IN UINTN NanoSeconds
)
{
UINTN MicroSeconds;
// Round up to 1us Tick Number
MicroSeconds = NanoSeconds / 1000;
MicroSeconds += ((NanoSeconds % 1000) == 0) ? 0 : 1;
MicroSecondDelay (MicroSeconds);
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
)
{
// Just return the value of system count
return ArmArchTimerGetSystemCount ();
}
/**
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
)
{
if (StartValue != NULL) {
// Timer starts with the reload value
*StartValue = (UINT64)0ULL ;
}
if (EndValue != NULL) {
// Timer counts down to 0x0
*EndValue = 0xFFFFFFFFFFFFFFFFUL;
}
return (UINT64)ArmArchTimerGetTimerFreq ();
}
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