x86_64: implement legacy PIT driver

5 files changed, 97 insertions, 1 deletions

diff --git a/arch/x86_64/CMakeLists.txt b/arch/x86_64/CMakeLists.txt
index 21dceef..83cae0b 100644
--- a/arch/x86_64/CMakeLists.txt
+++ b/arch/x86_64/CMakeLists.txt
@@ -37,6 +37,9 @@ target_sources("x86_64" PRIVATE
     # Debug interfaces
     "src/debug/qemu_output.cpp"
 
+    # Devices
+    "src/devices/legacy_pit.cpp"
+
     # Memory management
     "src/memory/kernel_mapper.cpp"
     "src/memory/higher_half_mapper.cpp"
diff --git a/arch/x86_64/include/arch/devices/legacy_pit.hpp b/arch/x86_64/include/arch/devices/legacy_pit.hpp
new file mode 100644
index 0000000..d28e4d6
--- /dev/null
+++ b/arch/x86_64/include/arch/devices/legacy_pit.hpp
@@ -0,0 +1,28 @@
+#ifndef TEACHOS_ARCH_X86_64_DEVICES_LEGACY_PIT_HPP
+#define TEACHOS_ARCH_X86_64_DEVICES_LEGACY_PIT_HPP
+
+#include "kapi/devices/device.hpp"
+#include "kapi/interrupts.hpp"
+
+#include <cstdint>
+
+namespace arch::devices
+{
+
+  struct legacy_pit : kapi::devices::device, kapi::interrupts::handler
+  {
+    explicit legacy_pit(std::uint32_t frequency_in_hz);
+
+    auto init() -> bool override;
+
+    auto handle_interrupt(std::uint32_t irq_number) -> kapi::interrupts::status override;
+
+  private:
+    std::uint32_t m_irq_number{};
+    std::uint32_t m_frequency_in_hz{};
+    std::uint64_t m_ticks{};
+  };
+
+}  // namespace arch::devices
+
+#endif
\ No newline at end of file
diff --git a/arch/x86_64/kapi/devices.cpp b/arch/x86_64/kapi/devices.cpp
index 25185d6..7aa7090 100644
--- a/arch/x86_64/kapi/devices.cpp
+++ b/arch/x86_64/kapi/devices.cpp
@@ -1,20 +1,31 @@
 #include "kapi/devices.hpp"
 
 #include "arch/bus/isa.hpp"
+#include "arch/devices/legacy_pit.hpp"
 
 #include <kstd/memory>
 #include <kstd/print>
 
+#include <cstdint>
 #include <utility>
 
 namespace kapi::devices
 {
 
+  namespace
+  {
+    constexpr auto pit_frequency_in_hz = std::uint32_t{100u};
+  }
+
   auto init_platform_devices() -> void
   {
     kstd::println("[x86_64:devices] Initializing ISA bus...");
+
     auto isa_bus = kstd::make_unique<arch::bus::isa>();
 
+    auto pit = kstd::make_unique<arch::devices::legacy_pit>(pit_frequency_in_hz);
+    isa_bus->add_child(std::move(pit));
+
     auto & root_bus = get_root_bus();
     root_bus.add_child(std::move(isa_bus));
   }
diff --git a/arch/x86_64/src/cpu/initialization.cpp b/arch/x86_64/src/cpu/initialization.cpp
index 878fa07..b808c76 100644
--- a/arch/x86_64/src/cpu/initialization.cpp
+++ b/arch/x86_64/src/cpu/initialization.cpp
@@ -139,7 +139,7 @@ namespace arch::cpu
     constexpr auto pic_cascade_address = std::uint8_t{0x04};
     constexpr auto pic_cascade_slave_identity = std::uint8_t{0x02};
     constexpr auto pic_use_8086_mode = std::uint8_t{0x01};
-    constexpr auto pic_master_mask = std::uint8_t{0x01};
+    constexpr auto pic_master_mask = std::uint8_t{0x00};
     constexpr auto pic_slave_mask = std::uint8_t{0x00};
 
     pic_master_control_port::write(pic_init_command);
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..f2fb70e
--- /dev/null
+++ b/arch/x86_64/src/devices/legacy_pit.cpp
@@ -0,0 +1,54 @@
+#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 <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>;
+  }  // namespace
+
+  legacy_pit::legacy_pit(std::uint32_t frequency_in_hz)
+      : kapi::devices::device{kapi::devices::allocate_major_number(), 0, "legacy_pit"}
+      , m_irq_number{0}
+      , m_frequency_in_hz{frequency_in_hz}
+  {}
+
+  auto legacy_pit::init() -> bool
+  {
+    constexpr auto base_frequency = 1'193'182u;
+    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>(0x36);                   // NOLINT
+    channel_0_port::write<std::uint8_t>(divisor & 0xff);       // NOLINT
+    channel_0_port::write<std::uint8_t>(divisor >> 8 & 0xff);  // NOLINT
+
+    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