1 files changed, 126 insertions, 0 deletions
diff --git a/Kernel/Time/HPETComparator.cpp b/Kernel/Time/HPETComparator.cpp
new file mode 100644
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+++ b/Kernel/Time/HPETComparator.cpp
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+/*
+ * Copyright (c) 2020, Liav A. <liavalb@hotmail.co.il>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <Kernel/Assertions.h>
+#include <Kernel/Time/HPETComparator.h>
+#include <Kernel/Time/TimeManagement.h>
+
+//#define HPET_COMPARATOR_DEBUG
+
+namespace Kernel {
+
+NonnullRefPtr<HPETComparator> HPETComparator::create(u8 number, u8 irq, bool periodic_capable)
+{
+    return adopt(*new HPETComparator(number, irq, periodic_capable, [](const RegisterState& regs) { TimeManagement::stale_function(regs); }));
+}
+
+HPETComparator::HPETComparator(u8 number, u8 irq, bool periodic_capable, Function<void(const RegisterState&)> callback)
+    : HardwareTimer(irq, move(callback))
+    , m_periodic(false)
+    , m_periodic_capable(periodic_capable)
+    , m_comparator_number(number)
+{
+}
+
+void HPETComparator::set_periodic()
+{
+    ASSERT(m_periodic_capable);
+    HPET::the().enable_periodic_interrupt(*this);
+    m_periodic = true;
+}
+void HPETComparator::set_non_periodic()
+{
+    ASSERT(m_periodic_capable);
+    HPET::the().disable_periodic_interrupt(*this);
+    m_periodic = false;
+}
+
+void HPETComparator::handle_irq(const RegisterState& regs)
+{
+    HardwareTimer::handle_irq(regs);
+    if (!is_periodic())
+        set_new_countdown();
+}
+
+void HPETComparator::set_new_countdown()
+{
+    ASSERT_INTERRUPTS_DISABLED();
+    ASSERT(m_frequency <= HPET::the().frequency());
+    HPET::the().set_non_periodic_comparator_value(*this, HPET::the().frequency() / m_frequency);
+}
+
+size_t HPETComparator::ticks_per_second() const
+{
+    return m_frequency;
+}
+
+void HPETComparator::reset_to_default_ticks_per_second()
+{
+    ASSERT(is_capable_of_frequency(OPTIMAL_TICKS_PER_SECOND_RATE));
+    m_frequency = OPTIMAL_TICKS_PER_SECOND_RATE;
+    if (!is_periodic())
+        set_new_countdown();
+    else
+        try_to_set_frequency(m_frequency);
+}
+bool HPETComparator::try_to_set_frequency(size_t frequency)
+{
+    InterruptDisabler disabler;
+    if (!is_capable_of_frequency(frequency))
+        return false;
+    disable_irq();
+    auto hpet_frequency = HPET::the().frequency();
+    ASSERT(frequency <= hpet_frequency);
+#ifdef HPET_COMPARATOR_DEBUG
+    dbg() << "HPET Comparator: Max frequency - " << hpet_frequency << " Hz, want to set " << frequency << " Hz";
+#endif
+    if (is_periodic())
+        HPET::the().set_periodic_comparator_value(*this, hpet_frequency / frequency);
+    else {
+        HPET::the().set_non_periodic_comparator_value(*this, hpet_frequency / frequency);
+        HPET::the().enable(*this);
+    }
+    m_frequency = frequency;
+    enable_irq();
+    return true;
+}
+bool HPETComparator::is_capable_of_frequency(size_t frequency) const
+{
+    if (frequency > HPET::the().frequency())
+        return false;
+    if ((HPET::the().frequency() % frequency) != 0)
+        return false;
+    return true;
+}
+size_t HPETComparator::calculate_nearest_possible_frequency(size_t frequency) const
+{
+    if (frequency >= HPET::the().frequency())
+        return HPET::the().frequency();
+    // FIXME: Use better math here
+    return (frequency + (HPET::the().frequency() % frequency));
+}
+
+}