ladybird/Kernel/Time/PIT.cpp
Daniel Bertalan 5f7f063919 Everywhere: Mark debug-only functions [[maybe_unused]]
These functions are only used from within `dbgln_if` calls, so in
certain build configurations, they go unused. Similarly to variables, we
now signal to the compiler that we understand that these are not always
in use.
2021-07-08 10:11:00 +02:00

91 lines
2.2 KiB
C++

/*
* Copyright (c) 2020, Liav A. <liavalb@hotmail.co.il>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <Kernel/Arch/x86/InterruptDisabler.h>
#include <Kernel/IO.h>
#include <Kernel/Interrupts/GenericInterruptHandler.h>
#include <Kernel/Interrupts/PIC.h>
#include <Kernel/Scheduler.h>
#include <Kernel/Sections.h>
#include <Kernel/Thread.h>
#include <Kernel/Time/PIT.h>
#include <Kernel/Time/TimeManagement.h>
#define IRQ_TIMER 0
namespace Kernel {
UNMAP_AFTER_INIT NonnullRefPtr<PIT> PIT::initialize(Function<void(const RegisterState&)> callback)
{
return adopt_ref(*new PIT(move(callback)));
}
[[maybe_unused]] inline static void reset_countdown(u16 timer_reload)
{
IO::out8(PIT_CTL, TIMER0_SELECT | WRITE_WORD | MODE_COUNTDOWN);
IO::out8(TIMER0_CTL, LSB(timer_reload));
IO::out8(TIMER0_CTL, MSB(timer_reload));
}
PIT::PIT(Function<void(const RegisterState&)> callback)
: HardwareTimer(IRQ_TIMER, move(callback))
, m_periodic(true)
{
IO::out8(PIT_CTL, TIMER0_SELECT | WRITE_WORD | MODE_SQUARE_WAVE);
dmesgln("PIT: {} Hz, square wave ({:#08x})", OPTIMAL_TICKS_PER_SECOND_RATE, BASE_FREQUENCY / OPTIMAL_TICKS_PER_SECOND_RATE);
reset_to_default_ticks_per_second();
enable_irq();
}
size_t PIT::ticks_per_second() const
{
return m_frequency;
}
void PIT::set_periodic()
{
// FIXME: Implement it...
VERIFY_NOT_REACHED();
}
void PIT::set_non_periodic()
{
// FIXME: Implement it...
VERIFY_NOT_REACHED();
}
void PIT::reset_to_default_ticks_per_second()
{
InterruptDisabler disabler;
bool success = try_to_set_frequency(OPTIMAL_TICKS_PER_SECOND_RATE);
VERIFY(success);
}
bool PIT::try_to_set_frequency(size_t frequency)
{
InterruptDisabler disabler;
if (!is_capable_of_frequency(frequency))
return false;
disable_irq();
size_t reload_value = BASE_FREQUENCY / frequency;
IO::out8(TIMER0_CTL, LSB(reload_value));
IO::out8(TIMER0_CTL, MSB(reload_value));
m_frequency = frequency;
enable_irq();
return true;
}
bool PIT::is_capable_of_frequency(size_t frequency) const
{
VERIFY(frequency != 0);
return frequency <= BASE_FREQUENCY;
}
size_t PIT::calculate_nearest_possible_frequency(size_t frequency) const
{
VERIFY(frequency != 0);
return frequency;
}
}