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[kernel] Add HPET support, create clock class

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Create a clock class which can be queried for current timestamp in
nanoseconds. Also implements a simple HPET class as one possible clock
source.

Tags: time
This commit is contained in:
Justin C. Miller
2020-06-28 17:47:46 -07:00
parent 9b67f87062
commit 6c468a134b
13 changed files with 347 additions and 36 deletions
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43
src/kernel/apic.cpp
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@@ -1,5 +1,6 @@
#include "kutil/assert.h"
#include "apic.h"
#include "clock.h"
#include "interrupts.h"
#include "io.h"
#include "log.h"
@@ -67,36 +68,20 @@ lapic::calibrate_timer()
log::info(logs::apic, "Calibrating APIC timer...");
// Set up PIT sleep
uint8_t command = 0x30; // channel 0, loybyte/highbyte, mode 0
outb(0x43, command);
const uint32_t initial = -1u;
enable_timer(isr::isrSpurious);
set_divisor(1);
apic_write(m_base, lapic_timer_init, initial);
const int iterations = 5;
for (int i=0; i<iterations; ++i) {
const uint16_t pit_33ms = 39375;
uint16_t pit_count = pit_33ms;
outb(0x40, pit_count & 0xff);
io_wait();
outb(0x40, (pit_count >> 8) & 0xff);
while (pit_count <= pit_33ms) {
outb(0x43, 0); // latch counter values
pit_count =
static_cast<uint16_t>(inb(0x40)) |
static_cast<uint16_t>(inb(0x40)) << 8;
}
}
uint64_t us = 200000;
uint64_t ns = us * 1000;
clock::get().spinwait(ns);
uint32_t remaining = apic_read(m_base, lapic_timer_cur);
uint32_t ticks_total = initial - remaining;
m_ticks_per_us = ticks_total / (iterations * 33000);
log::info(logs::apic, "APIC timer ticks %d times per nanosecond.", m_ticks_per_us);
m_ticks_per_us = ticks_total / us;
log::info(logs::apic, "APIC timer ticks %d times per microsecond.", m_ticks_per_us);
interrupts_enable();
}
@@ -123,14 +108,6 @@ lapic::set_divisor(uint8_t divisor)
m_divisor = divisor;
}
uint32_t
lapic::enable_timer_internal(isr vector, uint8_t divisor, uint32_t count, bool repeat)
{
reset_timer(count);
return count;
}
void
lapic::enable_timer(isr vector, bool repeat)
{
@@ -224,6 +201,9 @@ ioapic::ioapic(uint32_t *base, uint32_t base_gsi) :
void
ioapic::redirect(uint8_t irq, isr vector, uint16_t flags, bool masked)
{
log::debug(logs::apic, "IOAPIC %d redirecting irq %3d to vector %3d [%04x]%s",
m_id, irq, vector, flags, masked ? " (masked)" : "");
uint64_t entry = static_cast<uint64_t>(vector);
uint16_t polarity = flags & 0x3;
@@ -244,6 +224,9 @@ ioapic::redirect(uint8_t irq, isr vector, uint16_t flags, bool masked)
void
ioapic::mask(uint8_t irq, bool masked)
{
log::debug(logs::apic, "IOAPIC %d %smasking irq %3d",
m_id, masked ? "" : "un", irq);
uint32_t entry = ioapic_read(m_base, (2 * irq) + 0x10);
if (masked)
entry |= (1 << 16);