x86_64: implement legacy PIT driver

10 files changed, 146 insertions, 25 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
diff --git a/kapi/include/kapi/devices.hpp b/kapi/include/kapi/devices.hpp
index 2028a64..5c01b2f 100644
--- a/kapi/include/kapi/devices.hpp
+++ b/kapi/include/kapi/devices.hpp
@@ -1,10 +1,9 @@
 #ifndef TEACHOS_KAPI_DEVICES_HPP
 #define TEACHOS_KAPI_DEVICES_HPP
 
-#include "kapi/devices/bus.hpp"     // IWYU pragma: export
-#include "kapi/devices/device.hpp"  // IWYU pragma: export
-
-#include <cstddef>
+#include "kapi/devices/bus.hpp"      // IWYU pragma: export
+#include "kapi/devices/device.hpp"   // IWYU pragma: export
+#include "kapi/devices/manager.hpp"  // IWYU pragma: export
 
 namespace kapi::devices
 {
@@ -22,23 +21,6 @@ namespace kapi::devices
   //! @return a reference to the root bus.
   auto get_root_bus() -> bus &;
 
-  //! Ask the kernel to allocate a new major number.
-  //!
-  //! @return a new, unused major number.
-  auto allocate_major_number() -> std::size_t;
-
-  //! Register a new device with the kernel's device manager.
-  //!
-  //! @param device The device to register.
-  //! @return true if the device was registered successfully, false otherwise.
-  auto register_device(device & device) -> bool;
-
-  //! Unregister a device from the kernel's device manager.
-  //!
-  //! @param device The device to unregister.
-  //! @return true if the device was unregistered successfully, false otherwise.
-  auto unregister_device(device & device) -> bool;
-
   //! @}
 
   //! @addtogroup platform-defined
diff --git a/kapi/include/kapi/devices/bus.hpp b/kapi/include/kapi/devices/bus.hpp
index ccaf0f2..a5457e1 100644
--- a/kapi/include/kapi/devices/bus.hpp
+++ b/kapi/include/kapi/devices/bus.hpp
@@ -2,6 +2,7 @@
 #define TEACHOS_KAPI_DEVICES_BUS_HPP
 
 #include "kapi/devices/device.hpp"
+#include "kapi/devices/manager.hpp"
 #include "kapi/system.hpp"
 
 #include <kstd/memory>
@@ -58,6 +59,7 @@ namespace kapi::devices
     {
       auto observer = m_observers.emplace_back(child.get());
       m_devices.push_back(std::move(child));
+      kapi::devices::register_device(*observer);
 
       if (m_initialized.test())
       {
diff --git a/kapi/include/kapi/devices/manager.hpp b/kapi/include/kapi/devices/manager.hpp
new file mode 100644
index 0000000..56cd678
--- /dev/null
+++ b/kapi/include/kapi/devices/manager.hpp
@@ -0,0 +1,37 @@
+#ifndef TEACHOS_KAPI_DEVICES_MANAGER_HPP
+#define TEACHOS_KAPI_DEVICES_MANAGER_HPP
+
+// IWYU pragma: private, include "kapi/devices.hpp"
+
+#include "kapi/devices/device.hpp"
+
+#include <cstddef>
+
+namespace kapi::devices
+{
+
+  //! @addtogroup kernel-defined
+  //! @{
+
+  //! Ask the kernel to allocate a new major number.
+  //!
+  //! @return a new, unused major number.
+  auto allocate_major_number() -> std::size_t;
+
+  //! Register a new device with the kernel's device manager.
+  //!
+  //! @param device The device to register.
+  //! @return true if the device was registered successfully, false otherwise.
+  auto register_device(device & device) -> bool;
+
+  //! Unregister a device from the kernel's device manager.
+  //!
+  //! @param device The device to unregister.
+  //! @return true if the device was unregistered successfully, false otherwise.
+  auto unregister_device(device & device) -> bool;
+
+  //! @}
+
+}  // namespace kapi::devices
+
+#endif
\ No newline at end of file
diff --git a/kernel/kapi/devices.cpp b/kernel/kapi/devices.cpp
index dbf5e68..c0b738e 100644
--- a/kernel/kapi/devices.cpp
+++ b/kernel/kapi/devices.cpp
@@ -31,8 +31,9 @@ namespace kapi::devices
       return;
     }
 
-    root_bus.emplace();
-    root_bus->init();
+    auto & bus = root_bus.emplace();
+    register_device(bus);
+    bus.init();
   }
 
   auto get_root_bus() -> bus &
@@ -51,6 +52,7 @@ namespace kapi::devices
 
   auto register_device(device & device) -> bool
   {
+    kstd::println("[OS:DEV] Registering device {}@{}:{}", device.name(), device.major(), device.minor());
     return device_tree.emplace(std::pair{device.major(), device.minor()}, &device).second;
   }
 
diff --git a/kernel/src/main.cpp b/kernel/src/main.cpp
index eaaf87f..2eaa2d8 100644
--- a/kernel/src/main.cpp
+++ b/kernel/src/main.cpp
@@ -173,7 +173,6 @@ auto main() -> int
   kstd::println("[OS] IO subsystem initialized.");
 
   kapi::cpu::init();
-  kapi::interrupts::enable();
 
   kapi::memory::init();
   kernel::memory::init_heap(kapi::memory::heap_base);
@@ -186,6 +185,9 @@ auto main() -> int
   kapi::devices::init_platform_devices();
   kstd::println("[OS] Platform devices initialized.");
 
+  kapi::interrupts::enable();
+  kstd::println("[OS] Interrupts enabled.");
+
   kapi::boot_modules::init();
   kstd::println("[OS] Boot module registry initialized.");