mirror of
https://github.com/RGBCube/serenity
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95 lines
2.8 KiB
C++
95 lines
2.8 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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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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#include <Kernel/Arch/i386/CPU.h>
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#include <Kernel/Devices/PIT.h>
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#include <Kernel/Interrupts/PIC.h>
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#include <Kernel/Scheduler.h>
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#include <Kernel/Thread.h>
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#include <LibBareMetal/IO.h>
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#define IRQ_TIMER 0
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namespace Kernel {
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//#define PIT_DEBUG
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static PIT* s_the;
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void PIT::initialize()
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{
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if (s_the == nullptr) {
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s_the = new PIT();
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}
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}
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PIT& PIT::the()
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{
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ASSERT(s_the != nullptr);
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return *s_the;
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}
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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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void PIT::handle_irq(RegisterState& regs)
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{
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#ifdef PIT_DEBUG
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dbg() << "PIT: Debugging Interrupt.";
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#endif
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if (++m_ticks_this_second >= TICKS_PER_SECOND) {
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// FIXME: Synchronize with the RTC somehow to prevent drifting apart.
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++m_seconds_since_boot;
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m_ticks_this_second = 0;
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}
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Scheduler::timer_tick(regs);
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}
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u32 PIT::ticks_this_second() const
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{
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return m_ticks_this_second;
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}
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PIT::PIT()
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: HardwareTimer(IRQ_TIMER)
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, m_default_timer_reload(BASE_FREQUENCY / TICKS_PER_SECOND)
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, m_ticks_this_second(0)
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{
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IO::out8(PIT_CTL, TIMER0_SELECT | WRITE_WORD | MODE_SQUARE_WAVE);
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kprintf("PIT: %u Hz, square wave (%x)\n", TICKS_PER_SECOND, m_default_timer_reload);
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IO::out8(TIMER0_CTL, LSB(m_default_timer_reload));
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IO::out8(TIMER0_CTL, MSB(m_default_timer_reload));
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enable_irq();
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}
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}
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