40 lines
890 B
C
40 lines
890 B
C
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#include <kernel/printf.h>
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#include <kernel/process.h>
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#include <kernel/arch/x86_64/ports.h>
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#include <kernel/arch/x86_64/irq.h>
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#include <kernel/arch/x86_64/regs.h>
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/* Programmable interval timer */
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#define PIT_A 0x40
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#define PIT_B 0x41
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#define PIT_C 0x42
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#define PIT_CONTROL 0x43
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#define PIT_MASK 0xFF
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#define PIT_SCALE 1193180
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#define PIT_SET 0x34
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#define TIMER_IRQ 0
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#define RESYNC_TIME 1
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static void pit_set_timer_phase(long hz) {
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long divisor = PIT_SCALE / hz;
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outportb(PIT_CONTROL, PIT_SET);
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outportb(PIT_A, divisor & PIT_MASK);
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outportb(PIT_A, (divisor >> 8) & PIT_MASK);
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}
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extern int cmos_time_stuff(struct regs *r);
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void pit_initialize(void) {
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irq_install_handler(TIMER_IRQ, cmos_time_stuff, "pit timer");
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/* ELCR? */
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uint8_t val = inportb(0x4D1);
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outportb(0x4D1, val | (1 << (10-8)) | (1 << (11-8)));
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/* Enable PIT */
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pit_set_timer_phase(100); /* 1000 Hz */
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}
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