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89 lines
2.2 KiB
C++
89 lines
2.2 KiB
C++
/*
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* Copyright (c) 2020, Liav A. <liavalb@hotmail.co.il>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <Kernel/Arch/x86/InterruptDisabler.h>
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#include <Kernel/IO.h>
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#include <Kernel/Interrupts/GenericInterruptHandler.h>
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#include <Kernel/Scheduler.h>
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#include <Kernel/Sections.h>
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#include <Kernel/Thread.h>
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#include <Kernel/Time/PIT.h>
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#include <Kernel/Time/TimeManagement.h>
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#define IRQ_TIMER 0
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namespace Kernel {
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UNMAP_AFTER_INIT NonnullRefPtr<PIT> PIT::initialize(Function<void(const RegisterState&)> callback)
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{
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return adopt_ref(*new PIT(move(callback)));
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}
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[[maybe_unused]] inline static void reset_countdown(u16 timer_reload)
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{
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IO::out8(PIT_CTL, TIMER0_SELECT | WRITE_WORD | MODE_COUNTDOWN);
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IO::out8(TIMER0_CTL, LSB(timer_reload));
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IO::out8(TIMER0_CTL, MSB(timer_reload));
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}
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PIT::PIT(Function<void(const RegisterState&)> callback)
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: HardwareTimer(IRQ_TIMER, move(callback))
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, m_periodic(true)
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{
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IO::out8(PIT_CTL, TIMER0_SELECT | WRITE_WORD | MODE_SQUARE_WAVE);
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dmesgln("PIT: {} Hz, square wave ({:#08x})", OPTIMAL_TICKS_PER_SECOND_RATE, BASE_FREQUENCY / OPTIMAL_TICKS_PER_SECOND_RATE);
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reset_to_default_ticks_per_second();
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enable_irq();
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}
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size_t PIT::ticks_per_second() const
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{
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return m_frequency;
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}
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void PIT::set_periodic()
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{
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// FIXME: Implement it...
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VERIFY_NOT_REACHED();
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}
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void PIT::set_non_periodic()
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{
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// FIXME: Implement it...
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VERIFY_NOT_REACHED();
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}
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void PIT::reset_to_default_ticks_per_second()
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{
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InterruptDisabler disabler;
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bool success = try_to_set_frequency(OPTIMAL_TICKS_PER_SECOND_RATE);
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VERIFY(success);
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}
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bool PIT::try_to_set_frequency(size_t frequency)
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{
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InterruptDisabler disabler;
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if (!is_capable_of_frequency(frequency))
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return false;
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disable_irq();
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size_t reload_value = BASE_FREQUENCY / frequency;
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IO::out8(TIMER0_CTL, LSB(reload_value));
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IO::out8(TIMER0_CTL, MSB(reload_value));
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m_frequency = frequency;
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enable_irq();
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return true;
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}
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bool PIT::is_capable_of_frequency(size_t frequency) const
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{
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VERIFY(frequency != 0);
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return frequency <= BASE_FREQUENCY;
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}
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size_t PIT::calculate_nearest_possible_frequency(size_t frequency) const
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{
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VERIFY(frequency != 0);
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return frequency;
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}
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}
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