1 files changed, 60 insertions, 0 deletions
diff --git a/arch/x86_64/src/devices/legacy_pit.cpp b/arch/x86_64/src/devices/legacy_pit.cpp
new file mode 100644
index 0000000..a8df3c3
--- /dev/null
+++ b/arch/x86_64/src/devices/legacy_pit.cpp
@@ -0,0 +1,60 @@
+#include "arch/devices/legacy_pit.hpp"
+
+#include "kapi/devices.hpp"
+#include "kapi/devices/device.hpp"
+#include "kapi/interrupts.hpp"
+
+#include "arch/device_io/port_io.hpp"
+
+#include <cstddef>
+#include <cstdint>
+
+namespace arch::devices
+{
+
+  namespace
+  {
+    using command_port = io::port<0x43, std::uint8_t, io::port_write>;
+    using channel_0_port = io::port<0x40, std::uint8_t, io::port_write>;
+    using channel_1_port = io::port<0x41, std::uint8_t, io::port_write>;
+    using channel_2_port = io::port<0x42, std::uint8_t, io::port_write>;
+
+    constexpr auto base_frequency = 1'193'182u;
+    constexpr auto square_wave_mode = 0x36;
+  }  // namespace
+
+  legacy_pit::legacy_pit(std::size_t major, std::uint32_t frequency_in_hz)
+      : kapi::devices::device{major, 0, "legacy_pit"}
+      , m_irq_number{0}
+      , m_frequency_in_hz{frequency_in_hz}
+  {}
+
+  auto legacy_pit::init() -> bool
+  {
+    auto divisor = static_cast<std::uint16_t>(base_frequency / m_frequency_in_hz);
+
+    kapi::interrupts::register_handler(m_irq_number, *this);
+
+    command_port::write<std::uint8_t>(square_wave_mode);
+    io::wait();
+    channel_0_port::write<std::uint8_t>(divisor & 0xff);
+    io::wait();
+    channel_0_port::write<std::uint8_t>(divisor >> 8 & 0xff);
+    io::wait();
+
+    return true;
+  }
+
+  auto legacy_pit::handle_interrupt(std::uint32_t irq_number) -> kapi::interrupts::status
+  {
+    if (irq_number != m_irq_number)
+    {
+      return kapi::interrupts::status::unhandled;
+    }
+
+    ++m_ticks;
+
+    return kapi::interrupts::status::handled;
+  }
+
+}  // namespace arch::devices
+\ No newline at end of file