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/*
* Copyright (c) 2020, the SerenityOS developers
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <Kernel/Arch/i386/CPU.h>
#include <Kernel/IO.h>
#include <Kernel/Interrupts/APIC.h>
#include <Kernel/Scheduler.h>
#include <Kernel/Thread.h>
#include <Kernel/Time/APICTimer.h>
#include <Kernel/Time/TimeManagement.h>
namespace Kernel {
#define APIC_TIMER_MEASURE_CPU_CLOCK
APICTimer* APICTimer::initialize(u8 interrupt_number, HardwareTimerBase& calibration_source)
{
auto* timer = new APICTimer(interrupt_number, nullptr);
if (!timer->calibrate(calibration_source)) {
delete timer;
return nullptr;
}
return timer;
}
APICTimer::APICTimer(u8 interrupt_number, Function<void(const RegisterState&)> callback)
: HardwareTimer<GenericInterruptHandler>(interrupt_number, move(callback))
{
disable_remap();
}
bool APICTimer::calibrate(HardwareTimerBase& calibration_source)
{
ASSERT_INTERRUPTS_DISABLED();
klog() << "APICTimer: Using " << calibration_source.model() << " as calibration source";
auto& apic = APIC::the();
#ifdef APIC_TIMER_MEASURE_CPU_CLOCK
bool supports_tsc = Processor::current().has_feature(CPUFeature::TSC);
#endif
// temporarily replace the timer callbacks
const size_t ticks_in_100ms = calibration_source.ticks_per_second() / 10;
Atomic<size_t> calibration_ticks = 0;
#ifdef APIC_TIMER_MEASURE_CPU_CLOCK
volatile u64 start_tsc = 0, end_tsc = 0;
#endif
volatile u32 start_apic_count = 0, end_apic_count = 0;
auto original_source_callback = calibration_source.set_callback([&](const RegisterState&) {
u32 current_timer_count = apic.get_timer_current_count();
#ifdef APIC_TIMER_MEASURE_CPU_CLOCK
u64 current_tsc = supports_tsc ? read_tsc() : 0;
#endif
auto prev_tick = calibration_ticks.fetch_add(1, AK::memory_order_acq_rel);
if (prev_tick == 0) {
#ifdef APIC_TIMER_MEASURE_CPU_CLOCK
start_tsc = current_tsc;
#endif
start_apic_count = current_timer_count;
} else if (prev_tick + 1 == ticks_in_100ms) {
#ifdef APIC_TIMER_MEASURE_CPU_CLOCK
end_tsc = current_tsc;
#endif
end_apic_count = current_timer_count;
}
});
// Setup a counter that should be much longer than our calibration time.
// We don't want the APIC timer to actually fire. We do however want the
// calbibration_source timer to fire so that we can read the current
// tick count from the APIC timer
auto original_callback = set_callback([&](const RegisterState&) {
klog() << "APICTimer: Timer fired during calibration!";
ASSERT_NOT_REACHED(); // TODO: How should we handle this?
});
apic.setup_local_timer(0xffffffff, APIC::TimerMode::Periodic, true);
sti();
// Loop for about 100 ms
while (calibration_ticks.load(AK::memory_order_relaxed) < ticks_in_100ms)
;
cli();
// Restore timer callbacks
calibration_source.set_callback(move(original_source_callback));
set_callback(move(original_callback));
disable_local_timer();
auto delta_apic_count = start_apic_count - end_apic_count; // The APIC current count register decrements!
m_timer_period = (delta_apic_count * apic.get_timer_divisor()) / ticks_in_100ms;
auto apic_freq = (delta_apic_count * apic.get_timer_divisor()) / apic.get_timer_divisor();
if (apic_freq < 1000000) {
klog() << "APICTimer: Frequency too slow!";
return false;
}
klog() << "APICTimer: Bus clock speed: " << (apic_freq / 1000000) << "." << (apic_freq % 1000000) << " MHz";
#ifdef APIC_TIMER_MEASURE_CPU_CLOCK
if (supports_tsc) {
auto delta_tsc = end_tsc - start_tsc;
klog() << "APICTimer: CPU clock speed: " << (delta_tsc / 1000000) << "." << (delta_tsc % 1000000) << " MHz";
}
#endif
// TODO: measure rather than assuming it matches?
m_frequency = calibration_source.ticks_per_second();
enable_local_timer();
return true;
}
void APICTimer::enable_local_timer()
{
APIC::the().setup_local_timer(m_timer_period, m_timer_mode, true);
}
void APICTimer::disable_local_timer()
{
APIC::the().setup_local_timer(0, APIC::TimerMode::OneShot, false);
}
size_t APICTimer::ticks_per_second() const
{
return m_frequency;
}
void APICTimer::set_periodic()
{
// FIXME: Implement it...
ASSERT_NOT_REACHED();
}
void APICTimer::set_non_periodic()
{
// FIXME: Implement it...
ASSERT_NOT_REACHED();
}
void APICTimer::reset_to_default_ticks_per_second()
{
}
bool APICTimer::try_to_set_frequency([[maybe_unused]] size_t frequency)
{
return true;
}
bool APICTimer::is_capable_of_frequency([[maybe_unused]] size_t frequency) const
{
return false;
}
size_t APICTimer::calculate_nearest_possible_frequency([[maybe_unused]] size_t frequency) const
{
return 0;
}
}
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