56 lines
975 B
C
56 lines
975 B
C
#include <socks/printk.h>
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#include <socks/cpu.h>
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#include <arch/ports.h>
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#include <arch/irq.h>
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static unsigned long long tick_counter = 0;
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static int pit_callback(void)
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{
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tick_counter++;
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return 0;
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}
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static struct irq_hook pit_irq_hook = {
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.irq_callback = pit_callback
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};
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void pit_start(unsigned int hz)
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{
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tick_counter = 0;
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unsigned int divisor = 1193180 / hz;
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outportb(0x43, 0x36);
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uint8_t lo = (uint8_t)(divisor & 0xFF);
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uint8_t hi = (uint8_t)((divisor >> 8) & 0xFF);
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outportb(0x40, lo);
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outportb(0x40, hi);
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hook_irq(IRQ0, &pit_irq_hook);
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}
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void pit_stop(void)
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{
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/* lowest possible frequency */
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unsigned int divisor = 1193180;
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outportb(0x43, 0x36);
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uint8_t lo = (uint8_t)(divisor & 0xFF);
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uint8_t hi = (uint8_t)((divisor >> 8) & 0xFF);
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outportb(0x40, lo);
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outportb(0x40, hi);
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unhook_irq(IRQ0, &pit_irq_hook);
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}
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void pit_wait(unsigned int ticks)
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{
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unsigned long long end = tick_counter + ticks;
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while (READ_ONCE(tick_counter) < end) {
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}
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}
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