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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <Kernel/Arch/i386/CPU.h>
#include <Kernel/Arch/i386/PIC.h>
#include <Kernel/Arch/i386/PIT.h>
#include <Kernel/Scheduler.h>
#include <LibBareMetal/IO.h>
namespace Kernel {
#define IRQ_TIMER 0
extern "C" void timer_interrupt_entry();
extern "C" void timer_interrupt_handler(RegisterState);
asm(
".globl timer_interrupt_entry \n"
"timer_interrupt_entry: \n"
" pushl $0x0\n"
" pusha\n"
" pushl %ds\n"
" pushl %es\n"
" pushl %fs\n"
" pushl %gs\n"
" pushl %ss\n"
" mov $0x10, %ax\n"
" mov %ax, %ds\n"
" mov %ax, %es\n"
" cld\n"
" call timer_interrupt_handler\n"
" add $0x4, %esp\n"
" popl %gs\n"
" popl %fs\n"
" popl %es\n"
" popl %ds\n"
" popa\n"
" add $0x4, %esp\n"
" iret\n");
static u32 s_ticks_this_second;
static u32 s_seconds_since_boot;
void timer_interrupt_handler(RegisterState regs)
{
clac();
IRQHandlerScope scope(IRQ_TIMER);
if (++s_ticks_this_second >= TICKS_PER_SECOND) {
// FIXME: Synchronize with the RTC somehow to prevent drifting apart.
++s_seconds_since_boot;
s_ticks_this_second = 0;
}
Scheduler::timer_tick(regs);
}
namespace PIT {
u32 ticks_this_second()
{
return s_ticks_this_second;
}
u32 seconds_since_boot()
{
return s_seconds_since_boot;
}
void initialize()
{
u16 timer_reload;
IO::out8(PIT_CTL, TIMER0_SELECT | WRITE_WORD | MODE_SQUARE_WAVE);
timer_reload = (BASE_FREQUENCY / TICKS_PER_SECOND);
kprintf("PIT: %u Hz, square wave (%x)\n", TICKS_PER_SECOND, timer_reload);
IO::out8(TIMER0_CTL, LSB(timer_reload));
IO::out8(TIMER0_CTL, MSB(timer_reload));
register_interrupt_handler(IRQ_VECTOR_BASE + IRQ_TIMER, timer_interrupt_entry);
PIC::enable(IRQ_TIMER);
}
}
}
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