76 lines
1.6 KiB
C++
76 lines
1.6 KiB
C++
#include <kernel/IDT.h>
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#include <kernel/InterruptController.h>
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#include <kernel/IO.h>
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#include <kernel/Scheduler.h>
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#include <kernel/Timer/PIT.h>
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#define TIMER0_CTL 0x40
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#define TIMER1_CTL 0x41
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#define TIMER2_CTL 0x42
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#define PIT_CTL 0x43
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#define SELECT_CHANNEL0 0x00
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#define SELECT_CHANNEL1 0x40
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#define SELECT_CHANNEL2 0x80
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#define ACCESS_HI 0x10
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#define ACCESS_LO 0x20
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#define MODE_SQUARE_WAVE 0x06
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#define BASE_FREQUENCY 1193182
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#define TICKS_PER_SECOND 1000
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#define MS_PER_S 1'000
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#define NS_PER_S 1'000'000'000
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namespace Kernel
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{
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static volatile uint64_t s_system_time = 0;
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void irq_handler()
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{
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s_system_time = s_system_time + 1;
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Kernel::Scheduler::get().timer_reschedule();
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}
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BAN::ErrorOr<BAN::UniqPtr<PIT>> PIT::create()
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{
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PIT* pit = new PIT();
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if (pit == nullptr)
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return BAN::Error::from_errno(ENOMEM);
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pit->initialize();
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return BAN::UniqPtr<PIT>::adopt(pit);
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}
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void PIT::initialize()
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{
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constexpr uint16_t timer_reload = BASE_FREQUENCY / TICKS_PER_SECOND;
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IO::outb(PIT_CTL, SELECT_CHANNEL0 | ACCESS_LO | ACCESS_HI | MODE_SQUARE_WAVE);
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IO::outb(TIMER0_CTL, (timer_reload >> 0) & 0xff);
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IO::outb(TIMER0_CTL, (timer_reload >> 8) & 0xff);
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IDT::register_irq_handler(PIT_IRQ, irq_handler);
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InterruptController::get().enable_irq(PIT_IRQ);
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}
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uint64_t PIT::ms_since_boot() const
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{
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return s_system_time * (MS_PER_S / TICKS_PER_SECOND);
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}
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timespec PIT::time_since_boot() const
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{
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uint64_t ticks = s_system_time;
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return timespec {
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.tv_sec = ticks / TICKS_PER_SECOND,
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.tv_nsec = (long)((ticks % TICKS_PER_SECOND) * (NS_PER_S / TICKS_PER_SECOND))
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};
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}
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}
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