Enable the PIC and add a timer.

This causes a GP fault after the timer runs for some time.
This commit is contained in:
Drew Galbraith 2023-05-29 21:52:01 -07:00
parent 80d2bf1aaa
commit 629dca278b
6 changed files with 76 additions and 0 deletions

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@ -5,6 +5,7 @@ add_executable(zion
debug/debug.cpp
interrupt/interrupt.cpp
interrupt/interrupt_enter.s
interrupt/timer.cpp
loader/elf_loader.cpp
loader/init_loader.cpp
memory/kernel_heap.cpp

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@ -2,6 +2,7 @@
#include <stdint.h>
#include "common/port.h"
#include "debug/debug.h"
#define IDT_INTERRUPT_GATE 0x8E
@ -95,13 +96,37 @@ extern "C" void interrupt_page_fault(InterruptFrame* frame) {
panic("PF");
}
#define PIC1_COMMAND 0x20
#define PIC1_DATA 0x21
#define PIC_EOI 0x20
uint64_t cnt = 0;
extern "C" void isr_timer();
extern "C" void interrupt_timer(InterruptFrame*) {
cnt++;
if (cnt % 1000 == 0) {
dbgln("timer: %u", cnt);
}
outb(PIC1_COMMAND, PIC_EOI);
}
void EnablePic() {
outb(PIC1_COMMAND, 0x11);
outb(PIC1_DATA, 0x20); // PIC1 offset.
outb(PIC1_DATA, 0x4);
outb(PIC1_DATA, 0x1);
}
void InitIdt() {
gIdt[0] = CreateDescriptor(isr_divide_by_zero);
gIdt[13] = CreateDescriptor(isr_protection_fault);
gIdt[14] = CreateDescriptor(isr_page_fault);
gIdt[32] = CreateDescriptor(isr_timer);
InterruptDescriptorTablePointer idtp{
.size = sizeof(gIdt),
.base = reinterpret_cast<uint64_t>(gIdt),
};
asm volatile("lidt %0" ::"m"(idtp));
EnablePic();
}

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@ -55,3 +55,5 @@ isr_\name:
isr_handler divide_by_zero
isr_handler protection_fault,1
isr_handler page_fault,1
isr_handler timer

41
zion/interrupt/timer.cpp Normal file
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@ -0,0 +1,41 @@
#include "interrupt/timer.h"
#include "common/port.h"
namespace {
// IO Ports
constexpr uint8_t kPit0Ctl = 0x40;
constexpr uint8_t kPit1Ctl = 0x41;
constexpr uint8_t kPit2Ctl = 0x42;
constexpr uint8_t kPitCmd = 0x43;
// Command Register
// Mode
constexpr uint8_t kPitMode0 = 0x00;
constexpr uint8_t kPitMode1 = 0x02;
constexpr uint8_t kPitMode2 = 0x04;
constexpr uint8_t kPitMode3 = 0x06;
constexpr uint8_t kPitMode4 = 0x08;
constexpr uint8_t kPitMode5 = 0x0A;
// R/W
constexpr uint8_t kCmdLatch = 0x00;
constexpr uint8_t kCmdRwLow = 0x10;
constexpr uint8_t kCmdRwHi = 0x20;
constexpr uint8_t kCmdRwBoth = 0x30;
// PIT Select
constexpr uint8_t kSelect0 = 0x00;
constexpr uint8_t kSelect1 = 0x40;
constexpr uint8_t kSelect2 = 0x80;
constexpr uint8_t kReadback = 0xC0;
constexpr uint32_t kPitFrequency = 1193182;
} // namespace
void SetFrequency(uint64_t hertz) {
uint16_t reload = kPitFrequency / hertz;
outb(kPitCmd, kPitMode3 | kCmdRwBoth | kSelect0);
outb(kPit0Ctl, reload & 0xFF);
outb(kPit0Ctl, reload >> 8);
}

5
zion/interrupt/timer.h Normal file
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@ -0,0 +1,5 @@
#pragma once
#include <stdint.h>
void SetFrequency(uint64_t hertz);

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@ -3,6 +3,7 @@
#include "common/gdt.h"
#include "debug/debug.h"
#include "interrupt/interrupt.h"
#include "interrupt/timer.h"
#include "loader/init_loader.h"
#include "memory/kernel_heap.h"
#include "memory/paging_util.h"
@ -21,6 +22,7 @@ extern "C" void zion() {
InitSyscall();
SetFrequency(/* hertz= */ 2000);
sched::InitScheduler();
sched::EnableScheduler();