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// MIT License, Copyright (c) 2020 Marvin Borner
#include <def.h>
#include <drivers/cpu.h>
#include <drivers/interrupts.h>
#include <drivers/rtc.h>
#include <drivers/timer.h>
#include <io.h>
#include <mem.h>
#include <proc.h>
static u32 timer_ticks = 0;
PROTECTED static u8 call_scheduler = 0;
CLEAR static void timer_phase(int hz)
{
int divisor = 3579545 / 3 / hz;
outb(0x43, 0x36); // 01 10 11 0b // CTR, RW, MODE, BCD
outb(0x40, (u8)(divisor & 0xFF));
outb(0x40, (u8)(divisor >> 8));
}
u32 timer_get(void)
{
return timer_ticks;
}
void timer_handler(struct regs *r)
{
if (timer_ticks >= U32_MAX)
timer_ticks = 0;
else
timer_ticks++;
if (call_scheduler)
scheduler(r);
}
// "Delay" function with CPU sleep
void timer_wait(u32 ticks)
{
u32 eticks = timer_ticks + ticks;
while (timer_ticks < eticks) {
__asm__ volatile("sti\nhlt\ncli");
}
}
CLEAR void scheduler_enable(void)
{
call_scheduler = 1;
irq_install_handler(0, timer_handler);
}
CLEAR void scheduler_disable(void)
{
call_scheduler = 0;
irq_install_handler(0, timer_handler);
}
static struct timer timer_struct(void)
{
struct proc *proc = proc_current();
struct timer timer = {
.rtc = rtc_stamp(),
.ticks.user = proc->ticks.user,
.ticks.kernel = proc->ticks.kernel,
.time = timer_get(),
};
return timer;
}
static res timer_read(void *buf, u32 offset, u32 count)
{
UNUSED(offset);
struct timer timer = timer_struct();
memcpy_user(buf, &timer, MIN(count, sizeof(timer)));
return MIN(count, sizeof(timer));
}
// Install timer handler into IRQ0
CLEAR void timer_install(void)
{
/* hpet_install(10000); // TODO: Find optimal femtosecond period */
/* if (!hpet) */
timer_phase(1000);
irq_install_handler(0, timer_handler);
struct io_dev *dev = zalloc(sizeof(*dev));
dev->read = timer_read;
io_add(IO_TIMER, dev);
}
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