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5f51d85184
This implements a number of changes related to time: * If a HPET is present, it is now used only as a system timer, unless the Local APIC timer is used (in which case the HPET timer will not trigger any interrupts at all). * If a HPET is present, the current time can now be as accurate as the chip can be, independently from the system timer. We now query the HPET main counter for the current time in CPU #0's system timer interrupt, and use that as a base line. If a high precision time is queried, that base line is used in combination with quering the HPET timer directly, which should give a much more accurate time stamp at the expense of more overhead. For faster time stamps, the more coarse value based on the last interrupt will be returned. This also means that any missed interrupts should not cause the time to drift. * The default system interrupt rate is reduced to about 250 per second. * Fix calculation of Thread CPU usage by using the amount of ticks they used rather than the number of times a context switch happened. * Implement CLOCK_REALTIME_COARSE and CLOCK_MONOTONIC_COARSE and use it for most cases where precise timestamps are not needed.
78 lines
2.9 KiB
C++
78 lines
2.9 KiB
C++
/*
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* Copyright (c) 2020, Liav A. <liavalb@hotmail.co.il>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include <AK/NonnullRefPtr.h>
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#include <AK/Types.h>
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#include <Kernel/Time/HardwareTimer.h>
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namespace Kernel {
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/* Timer related ports */
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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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/* Building blocks for PIT_CTL */
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#define TIMER0_SELECT 0x00
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#define TIMER1_SELECT 0x40
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#define TIMER2_SELECT 0x80
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#define MODE_COUNTDOWN 0x00
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#define MODE_ONESHOT 0x02
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#define MODE_RATE 0x04
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#define MODE_SQUARE_WAVE 0x06
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#define WRITE_WORD 0x30
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#define BASE_FREQUENCY 1193182
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class PIT final : public HardwareTimer<IRQHandler> {
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public:
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static NonnullRefPtr<PIT> initialize(Function<void(const RegisterState&)>);
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virtual HardwareTimerType timer_type() const override { return HardwareTimerType::i8253; }
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virtual const char* model() const override { return "i8254"; }
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virtual size_t ticks_per_second() const override;
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virtual bool is_periodic() const override { return m_periodic; }
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virtual bool is_periodic_capable() const override { return true; }
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virtual void set_periodic() override;
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virtual void set_non_periodic() override;
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virtual void disable() override { }
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virtual void reset_to_default_ticks_per_second() override;
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virtual bool try_to_set_frequency(size_t frequency) override;
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virtual bool is_capable_of_frequency(size_t frequency) const override;
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virtual size_t calculate_nearest_possible_frequency(size_t frequency) const override;
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private:
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explicit PIT(Function<void(const RegisterState&)>);
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bool m_periodic { true };
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};
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}
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