clock.cpp

Go to the documentation of this file.

 
#include <hardwarecommunication/clock.h>
#include <common/logger.h>
 
using namespace MaxOS;
using namespace MaxOS::common;
using namespace MaxOS::hardwarecommunication;
 
Clock::Clock(AdvancedProgrammableInterruptController* apic, uint16_t time_between_events)
: InterruptHandler(0x20),
  m_apic(apic),
  m_ticks_between_events(time_between_events)
{
    Logger::INFO() << "Setting up Clock \n";
 
    s_active_clock = this;
 
    // Get the stats from the clock
    uint8_t status = read_hardware_clock(0xB);
 
    // Store the clock status
    m_24_hour_clock = status & 0x02;
    m_binary = status & 0x04;
}
 
Clock::~Clock() = default;
 
void Clock::handle_interrupt() {
 
    // Clock has ticked
    m_ticks++;
    m_ticks_until_next_event--;
 
    // Dont raise events until needed
    if (m_ticks_until_next_event != 0)
        return;
 
    // Raise the time event
//    Time time = get_time();
//    raise_event(new TimeEvent(&time));
 
    // Reset
    m_ticks_until_next_event = m_ticks_between_events;
}
 
 
uint8_t Clock::read_hardware_clock(uint8_t address) {
 
    m_command_port.write(address);
    return m_data_port.read();
}
 
uint8_t Clock::binary_representation(uint8_t number) const {
 
    // Check if the conversion needed
    if (m_binary)
        return number;
 
    // Convert to the binary representation
    return ((number / 16) * 10) + (number & 0x0f);
}
 
void Clock::delay(uint32_t milliseconds) const {
 
    // Round the number of milliseconds UP to the nearest clock accuracy
    uint64_t rounded_milliseconds = (milliseconds + clock_accuracy - 1) / clock_accuracy;
 
    // Wait until the time has passed
    uint64_t ticks_until_delay_is_over = m_ticks + rounded_milliseconds;
    while (m_ticks < ticks_until_delay_is_over)
        asm volatile("nop");
}
 
void Clock::calibrate(uint64_t ms_per_tick) {
 
    Logger::INFO() << "Calibrating Clock \n";
    clock_accuracy = ms_per_tick;
 
    // Get the ticks per ms
    PIT pit(m_apic);
    m_pit_ticks_per_ms = pit.ticks_per_ms();
 
    // Calibrate the BSP apic to the desired time
    setup_apic_clock(m_apic->local_apic());
 
    Logger::DEBUG() << "Clock: Calibrated to " << ms_per_tick << "ms per kernel tick\n";
}
 
void Clock::setup_apic_clock(hardwarecommunication::LocalAPIC* local_apic) const {
 
    // Configure the clock to periodic mode
    uint32_t lvt = 0x20 | (1 << 17);
    local_apic->write(0x320, lvt);
 
    // Set the initial count
    local_apic->write(0x380, m_pit_ticks_per_ms * clock_accuracy);
 
    // Clear the interrupt mask for the clock
    lvt &= ~(1 << 16);
    local_apic->write(0x320, lvt);
}
 
common::time_t Clock::get_time() {
 
    // Wait for the clock to be ready
    while (read_hardware_clock(0xA) & 0x80)
        asm volatile("nop");
 
    // Read the time from the clock
    time_t time{};
    time.year = binary_representation(read_hardware_clock(0x9)) + 2000;
    time.month = binary_representation(read_hardware_clock(0x8));
    time.day = binary_representation(read_hardware_clock(0x7));
    time.hour = binary_representation(read_hardware_clock(0x4));
    time.minute = binary_representation(read_hardware_clock(0x2));
    time.second = binary_representation(read_hardware_clock(0x0));
 
    // If the clock is using 12hr format and PM is set then add 12 to the hour
    if (!m_24_hour_clock && (time.hour & 0x80) != 0)
        time.hour = ((time.hour & 0x7F) + 12) % 24;
 
    return time;
}
 
Clock *Clock::active_clock() {
    return s_active_clock;
}
 
PIT::PIT(AdvancedProgrammableInterruptController *apic)
: InterruptHandler(0x22),
  m_data_port(0x40),
  m_command_port(0x43),
  m_local_apic(apic->local_apic()),
  m_io_apic(apic->io_apic())
{
 
}
 
PIT::~PIT() = default;
 
void PIT::handle_interrupt() {
    m_ticks++;
}
 
uint32_t PIT::ticks_per_ms() {
 
    // Set the redirect for the timer interrupt
    interrupt_redirect_t redirect = {
            .type = 0x2,
            .index = 0x14,
            .interrupt = 0x22,
            .destination = 0x00,
            .flags = 0x00,
            .mask = true,
    };
    m_io_apic->set_redirect(&redirect);
 
    // Configure the PIT clock
    pit_command_t command = {
            .bcd_mode       = (uint8_t) BCDMode::BINARY,
            .operating_mode = (uint8_t) OperatingMode::RATE_GENERATOR,
            .access_mode    = (uint8_t) AccessMode::LOW_HIGH_BYTE,
            .channel        = (uint8_t) Channel::INTERRUPT
    };
    m_command_port.write(*(uint8_t *) &command);
 
    // Set the clock rate to 1 ms;
    uint16_t rate = 1193182 / 1000;
    m_data_port.write(rate & 0xFF);
    m_data_port.write(rate >> 8);
 
    // Stop the clock
    m_local_apic->write(0x380, 0x00);
 
    // Set the divisor to 2
    m_local_apic->write(0x3E0, 0x0);
 
    // Unmask the PIT interrupt
    m_io_apic->set_redirect_mask(redirect.index, false);
 
    // Calculate the number of ticks in 1 ms
    auto max = (uint32_t) -1;
    m_local_apic->write(0x380, max);
 
    while (m_ticks < TICK_CALIBRATE_LENGTH)
        asm volatile("nop");
 
    uint32_t elapsed = max - (m_local_apic->read(0x390));
    uint32_t ticks_per_ms = elapsed / TICK_CALIBRATE_LENGTH;
 
    Logger::DEBUG() << "Ticks per ms: " << (int) ticks_per_ms << "\n";
 
    // Disable the PIT interrupt again
    m_local_apic->write(0x380, 0x00);
    m_io_apic->set_redirect_mask(redirect.index, true);
 
    return ticks_per_ms;
}