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/*
* Copyright (c) 2020, the SerenityOS developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <Kernel/Interrupts/APIC.h>
#include <Kernel/Panic.h>
#include <Kernel/Sections.h>
#include <Kernel/Time/APICTimer.h>
#include <Kernel/Time/TimeManagement.h>
namespace Kernel {
#define APIC_TIMER_MEASURE_CPU_CLOCK
UNMAP_AFTER_INIT APICTimer* APICTimer::initialize(u8 interrupt_number, HardwareTimerBase& calibration_source)
{
auto timer = adopt_ref(*new APICTimer(interrupt_number, nullptr));
timer->register_interrupt_handler();
if (!timer->calibrate(calibration_source)) {
return nullptr;
}
return &timer.leak_ref();
}
UNMAP_AFTER_INIT APICTimer::APICTimer(u8 interrupt_number, Function<void(const RegisterState&)> callback)
: HardwareTimer<GenericInterruptHandler>(interrupt_number, move(callback))
{
disable_remap();
}
UNMAP_AFTER_INIT bool APICTimer::calibrate(HardwareTimerBase& calibration_source)
{
VERIFY_INTERRUPTS_DISABLED();
dmesgln("APICTimer: Using {} as calibration source", calibration_source.model());
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, AK::memory_order_relaxed> calibration_ticks = 0;
#ifdef APIC_TIMER_MEASURE_CPU_CLOCK
volatile u64 start_tsc = 0, end_tsc = 0;
#endif
volatile u64 start_reference = 0, end_reference = 0;
volatile u32 start_apic_count = 0, end_apic_count = 0;
bool query_reference = calibration_source.can_query_raw();
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
u64 current_reference = query_reference ? calibration_source.current_raw() : 0;
auto prev_tick = calibration_ticks.fetch_add(1);
if (prev_tick == 0) {
#ifdef APIC_TIMER_MEASURE_CPU_CLOCK
start_tsc = current_tsc;
#endif
start_apic_count = current_timer_count;
start_reference = current_reference;
} else if (prev_tick + 1 == ticks_in_100ms + 1) {
#ifdef APIC_TIMER_MEASURE_CPU_CLOCK
end_tsc = current_tsc;
#endif
end_apic_count = current_timer_count;
end_reference = current_reference;
}
});
// 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&) {
// TODO: How should we handle this?
PANIC("APICTimer: Timer fired during calibration!");
});
apic.setup_local_timer(0xffffffff, APIC::TimerMode::Periodic, true);
sti();
// Loop for about 100 ms
while (calibration_ticks.load() <= ticks_in_100ms)
;
cli();
// Restore timer callbacks
calibration_source.set_callback(move(original_source_callback));
set_callback(move(original_callback));
disable_local_timer();
if (query_reference) {
u64 one_tick_ns = calibration_source.raw_to_ns((end_reference - start_reference) / ticks_in_100ms);
m_frequency = (u32)(1000000000ull / one_tick_ns);
dmesgln("APICTimer: Ticks per second: {} ({}.{}ms)", m_frequency, one_tick_ns / 1000000, one_tick_ns % 1000000);
} else {
// For now, assume the frequency is exactly the same
m_frequency = calibration_source.ticks_per_second();
dmesgln("APICTimer: Ticks per second: {} (assume same frequency as reference clock)", m_frequency);
}
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;
u64 apic_freq = delta_apic_count * apic.get_timer_divisor() * 10;
dmesgln("APICTimer: Bus clock speed: {}.{} MHz", apic_freq / 1000000, apic_freq % 1000000);
if (apic_freq < 1000000) {
dmesgln("APICTimer: Frequency too slow!");
return false;
}
#ifdef APIC_TIMER_MEASURE_CPU_CLOCK
if (supports_tsc) {
auto delta_tsc = (end_tsc - start_tsc) * 10;
dmesgln("APICTimer: CPU clock speed: {}.{} MHz", delta_tsc / 1000000, delta_tsc % 1000000);
}
#endif
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...
VERIFY_NOT_REACHED();
}
void APICTimer::set_non_periodic()
{
// FIXME: Implement it...
VERIFY_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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