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Kernel/aarch64: Implement HardwareTimer for RPi::Timer

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This makes the RPi::Timer suitable for use in the TimeManagement code.
This commit is contained in:
Timon Kruiper 2022-10-17 14:59:35 +02:00 • committed by Gunnar Beutner
parent de0bb99893
commit 83b95c135e
3 changed files with 77 additions and 19 deletions
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57
Kernel/Arch/aarch64/RPi/Timer.cpp
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@ -1,5 +1,6 @@
/*
* Copyright (c) 2021, Nico Weber <thakis@chromium.org>
* Copyright (c) 2022, Timon Kruiper <timonkruiper@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
@ -30,15 +31,21 @@ enum FlagBits {
};
Timer::Timer()
: IRQHandler(1)
: HardwareTimer(1)
, m_registers(MMIO::the().peripheral<TimerRegisters>(0x3000))
{
// FIXME: Actually query the frequency of the timer. By default it is 100MHz.
m_frequency = 1e6;
set_interrupt_interval_usec(m_frequency / OPTIMAL_TICKS_PER_SECOND_RATE);
enable_interrupt_mode();
}
Timer& Timer::the()
Timer::~Timer() = default;
NonnullLockRefPtr<Timer> Timer::initialize()
{
static AK::NeverDestroyed<Timer> instance;
return *instance;
return adopt_lock_ref(*new Timer);
}
u64 Timer::microseconds_since_boot()
@ -52,23 +59,45 @@ u64 Timer::microseconds_since_boot()
return (static_cast<u64>(high) << 32) | low;
}
bool Timer::handle_irq(RegisterState const&)
bool Timer::handle_irq(RegisterState const& regs)
{
dmesgln("Timer fired: {} us", m_current_timer_value);
m_current_timer_value += m_interrupt_interval;
set_compare(TimerID::Timer1, m_current_timer_value);
auto result = HardwareTimer::handle_irq(regs);
set_compare(TimerID::Timer1, microseconds_since_boot() + m_interrupt_interval);
clear_interrupt(TimerID::Timer1);
return true;
return result;
};
u64 Timer::update_time(u64& seconds_since_boot, u32& ticks_this_second, bool query_only)
{
// Should only be called by the time keeper interrupt handler!
u64 current_value = microseconds_since_boot();
u64 delta_ticks = m_main_counter_drift;
if (current_value >= m_main_counter_last_read) {
delta_ticks += current_value - m_main_counter_last_read;
} else {
// the counter wrapped around
delta_ticks += (NumericLimits<u64>::max() - m_main_counter_last_read + 1) + current_value;
}
u64 ticks_since_last_second = (u64)ticks_this_second + delta_ticks;
auto ticks_per_second = frequency();
seconds_since_boot += ticks_since_last_second / ticks_per_second;
ticks_this_second = ticks_since_last_second % ticks_per_second;
if (!query_only) {
m_main_counter_drift = 0;
m_main_counter_last_read = current_value;
}
// Return the time passed (in ns) since last time update_time was called
return (delta_ticks * 1000000000ull) / ticks_per_second;
}
void Timer::enable_interrupt_mode()
{
m_current_timer_value = microseconds_since_boot();
m_current_timer_value += m_interrupt_interval;
set_compare(TimerID::Timer1, m_current_timer_value);
set_compare(TimerID::Timer1, microseconds_since_boot() + m_interrupt_interval);
enable_irq();
}