Kernel: Reorganize Arch/x86 directory to Arch/x86_64 after i686 removal

No functional change.

Kernel/Arch/x86_64/Time/RTC.cpp

@@ -0,0 +1,91 @@
+/*
+ * Copyright (c) 2020, Liav A. <liavalb@hotmail.co.il>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <Kernel/Arch/x86_64/CMOS.h>
+#include <Kernel/Arch/x86_64/IO.h>
+#include <Kernel/Arch/x86_64/NonMaskableInterruptDisabler.h>
+#include <Kernel/Arch/x86_64/Time/RTC.h>
+#include <Kernel/InterruptDisabler.h>
+#include <Kernel/Time/TimeManagement.h>
+
+namespace Kernel {
+#define IRQ_TIMER 8
+#define MAX_FREQUENCY 8000
+
+NonnullLockRefPtr<RealTimeClock> RealTimeClock::create(Function<void(RegisterState const&)> callback)
+{
+    return adopt_lock_ref(*new RealTimeClock(move(callback)));
+}
+RealTimeClock::RealTimeClock(Function<void(RegisterState const&)> callback)
+    : HardwareTimer(IRQ_TIMER, move(callback))
+{
+    InterruptDisabler disabler;
+    NonMaskableInterruptDisabler nmi_disabler;
+    enable_irq();
+    CMOS::write(0x8B, CMOS::read(0xB) | 0x40);
+    reset_to_default_ticks_per_second();
+}
+bool RealTimeClock::handle_irq(RegisterState const& regs)
+{
+    auto result = HardwareTimer::handle_irq(regs);
+    CMOS::read(0x8C);
+    return result;
+}
+
+size_t RealTimeClock::ticks_per_second() const
+{
+    return m_frequency;
+}
+
+void RealTimeClock::reset_to_default_ticks_per_second()
+{
+    InterruptDisabler disabler;
+    bool success = try_to_set_frequency(1024);
+    VERIFY(success);
+}
+
+// FIXME: This is a quick & dirty log base 2 with a parameter. Please provide something better in the future.
+static int quick_log2(size_t number)
+{
+    int count = 0;
+    while (number >>= 1)
+        count++;
+    return count;
+}
+
+bool RealTimeClock::try_to_set_frequency(size_t frequency)
+{
+    InterruptDisabler disabler;
+    if (!is_capable_of_frequency(frequency))
+        return false;
+    disable_irq();
+    u8 previous_rate = CMOS::read(0x8A);
+    u8 rate = quick_log2(32768 / frequency) + 1;
+    dbgln("RTC: Set rate to {}", rate);
+    CMOS::write(0x8A, (previous_rate & 0xF0) | rate);
+    m_frequency = frequency;
+    dbgln("RTC: Set frequency to {} Hz", frequency);
+    enable_irq();
+    return true;
+}
+bool RealTimeClock::is_capable_of_frequency(size_t frequency) const
+{
+    VERIFY(frequency != 0);
+    if (frequency > MAX_FREQUENCY)
+        return false;
+    if (32768 % frequency)
+        return false;
+
+    u16 divider = 32768 / frequency;
+    return (divider <= 16384 && divider >= 4); // Frequency can be in range of 2 Hz to 8 KHz
+}
+size_t RealTimeClock::calculate_nearest_possible_frequency(size_t frequency) const
+{
+    VERIFY(frequency != 0);
+    return frequency;
+}
+
+}