kapi: add automatic driver registrationHEADdevelop

12 files changed, 184 insertions, 51 deletions

diff --git a/arch/x86_64/CMakeLists.txt b/arch/x86_64/CMakeLists.txt
index 19022b5f..fc665c15 100644
--- a/arch/x86_64/CMakeLists.txt
+++ b/arch/x86_64/CMakeLists.txt
@@ -50,7 +50,6 @@ target_sources("x86_64" PRIVATE
     "arch/devices/cpu/lapic.cpp"
 
     # Drivers
-    "arch/drivers/init.cpp"
     "arch/drivers/cpu/lapic.cpp"
     "arch/drivers/pit.cpp"
 
diff --git a/arch/x86_64/arch/drivers/cpu/lapic.cpp b/arch/x86_64/arch/drivers/cpu/lapic.cpp
index 2f74abc4..f8aa8e90 100644
--- a/arch/x86_64/arch/drivers/cpu/lapic.cpp
+++ b/arch/x86_64/arch/drivers/cpu/lapic.cpp
@@ -4,9 +4,11 @@
 
 #include <kapi/capabilities/facet_id.hpp>
 #include <kapi/devices.hpp>
+#include <kapi/devices/driver_registry.hpp>
 #include <kapi/memory.hpp>
 
 #include <kstd/format.hpp>
+#include <kstd/memory.hpp>
 #include <kstd/mutex.hpp>
 #include <kstd/print.hpp>
 #include <kstd/result.hpp>
@@ -31,6 +33,22 @@ namespace arch::drivers::cpu
     constexpr auto offset_of_version = 0u;
     constexpr auto offset_of_max_lvt_entry = 16u;
     constexpr auto offset_of_eoi_suppression = 24u;
+
+    struct descriptor final : kapi::devices::driver_descriptor
+    {
+      [[nodiscard]] auto make_instance() const -> kstd::shared_ptr<kapi::devices::driver> override
+      {
+        return kstd::make_shared<lapic>();
+      }
+
+      [[nodiscard]] auto name() const noexcept -> std::string_view override
+      {
+        return "intel_lapic";
+      }
+    };
+
+    [[gnu::used]]
+    constexpr auto registration = kapi::devices::platform_driver<descriptor>{};
   }  // namespace
 
   enum struct lapic::registers : std::ptrdiff_t
@@ -164,4 +182,4 @@ namespace arch::drivers::cpu
     return kapi::devices::driver::query_facet(facet);
   }
 
-}  // namespace arch::drivers
+}  // namespace arch::drivers::cpu
diff --git a/arch/x86_64/arch/drivers/init.cpp b/arch/x86_64/arch/drivers/init.cpp
deleted file mode 100644
index 19f45829..00000000
--- a/arch/x86_64/arch/drivers/init.cpp
+++ /dev/null
@@ -1,29 +0,0 @@
-#include <arch/drivers/init.hpp>
-
-#include <arch/drivers/cpu/lapic.hpp>
-#include <arch/drivers/pit.hpp>
-
-#include <kapi/devices.hpp>
-
-#include <kstd/memory.hpp>
-
-#include <cstdint>
-
-namespace arch::drivers
-{
-
-  namespace
-  {
-    //! The interrupt frequency of the Programmable Interrupt Timer.
-    constexpr auto pit_frequency_in_hz = std::uint32_t{100u};
-  }  // namespace
-
-  auto init_legacy_drivers() -> void
-  {
-    auto & driver_registry = kapi::devices::driver_registry::get();
-
-    driver_registry.add(kstd::make_shared<pit>(pit_frequency_in_hz));
-    driver_registry.add(kstd::make_shared<cpu::lapic>());
-  }
-
-}  // namespace arch::drivers
diff --git a/arch/x86_64/arch/drivers/init.hpp b/arch/x86_64/arch/drivers/init.hpp
deleted file mode 100644
index 797edb0f..00000000
--- a/arch/x86_64/arch/drivers/init.hpp
+++ /dev/null
@@ -1,11 +0,0 @@
-#ifndef TEACHOS_ARCH_X86_64_DRIVERS_INIT_HPP
-#define TEACHOS_ARCH_X86_64_DRIVERS_INIT_HPP
-
-namespace arch::drivers
-{
-
-  auto init_legacy_drivers() -> void;
-
-}
-
-#endif
diff --git a/arch/x86_64/arch/drivers/pit.cpp b/arch/x86_64/arch/drivers/pit.cpp
index 49b3f228..e6e98796 100644
--- a/arch/x86_64/arch/drivers/pit.cpp
+++ b/arch/x86_64/arch/drivers/pit.cpp
@@ -29,6 +29,24 @@ namespace arch::drivers
     constexpr auto command_offset = 3u;
 
     constexpr auto pit_names = std::array{"pit"sv};
+    constexpr auto pit_frequency_in_hz = std::uint32_t{100u};
+
+    struct descriptor final : kapi::devices::driver_descriptor
+    {
+      [[nodiscard]] auto make_instance() const -> kstd::shared_ptr<kapi::devices::driver> override
+      {
+        return kstd::make_shared<pit>(pit_frequency_in_hz);
+      }
+
+      [[nodiscard]] auto name() const noexcept -> std::string_view override
+      {
+        return "i8253_pit"sv;
+      }
+    };
+
+    [[gnu::used]]
+    constexpr auto registration = kapi::devices::platform_driver<descriptor>{};
+
   }  // namespace
 
   pit::pit(std::uint32_t frequency_in_hz)
diff --git a/arch/x86_64/kapi/devices.cpp b/arch/x86_64/kapi/devices.cpp
index d9a0b2b9..888b6e20 100644
--- a/arch/x86_64/kapi/devices.cpp
+++ b/arch/x86_64/kapi/devices.cpp
@@ -2,11 +2,15 @@
 
 #include <arch/bus/cpu.hpp>
 #include <arch/devices/init.hpp>
-#include <arch/drivers/init.hpp>
 
+#include <kapi/devices/driver_registry.hpp>
 #include <kapi/system.hpp>
 
 #include <kstd/memory.hpp>
+#include <kstd/print.hpp>
+
+#include <ranges>
+#include <span>
 
 namespace kapi::devices
 {
@@ -16,9 +20,27 @@ namespace kapi::devices
     auto static constinit cpu_bus = kstd::shared_ptr<arch::bus::cpu>{};
   }
 
+  extern "C"
+  {
+    // We need to suppress clang-tidy linting warnings here, since these symbols are generated by the linker and we
+    // cannot choose their names, unless we wanted to extend the linker script needlessly.
+    // NOLINTBEGIN(readability-identifier-naming)
+    extern kstd::observer_ptr<kapi::devices::driver_descriptor> const __start_platform_drivers;
+    extern kstd::observer_ptr<kapi::devices::driver_descriptor> const __stop_platform_drivers;
+    // NOLINTEND(readability-identifier-naming)
+  }
+
   auto init_platform_drivers() -> void
   {
-    arch::drivers::init_legacy_drivers();
+    auto descriptors = std::span{&__start_platform_drivers, &__stop_platform_drivers} |  //
+                       std::views::filter([](auto p) { return p != nullptr; });
+
+    for (auto driver : descriptors)
+    {
+      auto instance = driver->make_instance();
+      kstd::println("[x86_64:DRV] registering driver '{}' ({})", instance->name(), driver->name());
+      kapi::devices::driver_registry::get().add(driver->make_instance());
+    }
   }
 
   auto init_platform_devices() -> void
diff --git a/arch/x86_64/scripts/kernel.ld b/arch/x86_64/scripts/kernel.ld
index dbb0f8f0..f621c3f1 100644
--- a/arch/x86_64/scripts/kernel.ld
+++ b/arch/x86_64/scripts/kernel.ld
@@ -75,9 +75,20 @@ SECTIONS
 
     . = ALIGN(8);
 
+    /* Filesystem driver factories */
     PROVIDE(__start_fs_types = .);
     KEEP(*(fs_types));
     PROVIDE(__stop_fs_types = .);
+
+    /* Kernel driver factories */
+    PROVIDE(__start_kernel_drivers = .);
+    KEEP(*(kernel_drivers));
+    PROVIDE(__stop_kernel_drivers = .);
+
+    /* Platform driver factories */
+    PROVIDE(__start_platform_drivers = .);
+    KEEP(*(platform_drivers));
+    PROVIDE(__stop_platform_drivers = .);
   } :kernel_rodata
 
   .kernel_data ALIGN(4K) : AT (ADDR (.kernel_data) - TEACHOS_VMA)
diff --git a/kapi/kapi/devices/driver_registry.hpp b/kapi/kapi/devices/driver_registry.hpp
index 8af76b01..196b14c1 100644
--- a/kapi/kapi/devices/driver_registry.hpp
+++ b/kapi/kapi/devices/driver_registry.hpp
@@ -8,9 +8,45 @@
 #include <kstd/memory.hpp>
 #include <kstd/vector.hpp>
 
+#include <string_view>
+
 namespace kapi::devices
 {
 
+  //! @addtogroup kapi-devices
+  //! @{
+
+  struct driver_descriptor
+  {
+    virtual ~driver_descriptor() = default;
+
+    //! Get the name of the driver
+    [[nodiscard]] virtual auto name() const noexcept -> std::string_view = 0;
+
+    //! Create a new instance of the driver represented by this descriptor.
+    [[nodiscard]] virtual auto make_instance() const -> kstd::shared_ptr<driver> = 0;
+  };
+
+  template<typename Type>
+  struct kernel_driver
+  {
+    constexpr auto static instance = Type{};
+    [[using gnu: section("kernel_drivers"), used, visibility("hidden")]] constexpr auto static pointer{
+      kstd::make_observer<kapi::devices::driver_descriptor const>(&instance),
+    };
+  };
+
+  template<typename Type>
+  struct platform_driver
+  {
+    constexpr auto static instance = Type{};
+    [[using gnu: section("platform_drivers"), used, visibility("hidden")]] constexpr auto static pointer{
+      kstd::make_observer<kapi::devices::driver_descriptor const>(&instance),
+    };
+  };
+
+  //! @}
+
   //! @addtogroup kapi-devices-kernel-defined
   //! @{
 
diff --git a/kernel/kernel/drivers/init.cpp b/kernel/kernel/drivers/init.cpp
index cd196fa8..97d8f0bc 100644
--- a/kernel/kernel/drivers/init.cpp
+++ b/kernel/kernel/drivers/init.cpp
@@ -1,25 +1,42 @@
 #include <kernel/drivers/init.hpp>
 
-#include <kernel/drivers/pseudo/null.hpp>
-#include <kernel/drivers/pseudo/zero.hpp>
-#include <kernel/drivers/storage/ram_disk.hpp>
-
+#include <kapi/devices.hpp>
 #include <kapi/devices/driver_registry.hpp>
 
 #include <kstd/memory.hpp>
+#include <kstd/print.hpp>
+
+#include <ranges>
+#include <span>
 
 namespace kernel::drivers
 {
 
+  extern "C"
+  {
+    // We need to suppress clang-tidy linting warnings here, since these symbols are generated by the linker and we
+    // cannot choose their names, unless we wanted to extend the linker script needlessly.
+    // NOLINTBEGIN(readability-identifier-naming)
+    extern kstd::observer_ptr<kapi::devices::driver_descriptor> const __start_kernel_drivers;
+    extern kstd::observer_ptr<kapi::devices::driver_descriptor> const __stop_kernel_drivers;
+    // NOLINTEND(readability-identifier-naming)
+  }
+
   auto init() -> void
   {
     kapi::devices::driver_registry::init();
 
     auto & registry = kapi::devices::driver_registry::get();
 
-    registry.add(kstd::make_shared<kernel::drivers::pseudo::null>());
-    registry.add(kstd::make_shared<kernel::drivers::pseudo::zero>());
-    registry.add(kstd::make_shared<kernel::drivers::storage::ram_disk>());
+    auto descriptors = std::span{&__start_kernel_drivers, &__stop_kernel_drivers} |  //
+                       std::views::filter([](auto p) { return p != nullptr; });
+
+    for (auto driver : descriptors)
+    {
+      auto instance = driver->make_instance();
+      kstd::println("[OS:DRV] registering driver '{}' ({})", instance->name(), driver->name());
+      registry.add(driver->make_instance());
+    }
   }
 
 }  // namespace kernel::drivers
\ No newline at end of file
diff --git a/kernel/kernel/drivers/pseudo/null.cpp b/kernel/kernel/drivers/pseudo/null.cpp
index d0df9000..4995cc25 100644
--- a/kernel/kernel/drivers/pseudo/null.cpp
+++ b/kernel/kernel/drivers/pseudo/null.cpp
@@ -4,6 +4,7 @@
 #include <kernel/filesystem/reserved_numbers.hpp>
 
 #include <kapi/devices.hpp>
+#include <kapi/devices/driver_registry.hpp>
 #include <kapi/filesystem.hpp>
 
 #include <kstd/memory.hpp>
@@ -26,6 +27,23 @@ namespace kernel::drivers::pseudo
 
   namespace
   {
+    struct descriptor final : kapi::devices::driver_descriptor
+    {
+    public:
+      [[nodiscard("")]] auto name() const noexcept -> std::string_view override
+      {
+        return "dev_null";
+      }
+
+      [[nodiscard("")]] auto make_instance() const -> kstd::shared_ptr<kapi::devices::driver> override
+      {
+        return kstd::make_shared<null>();
+      }
+    };
+
+    [[gnu::used]]
+    constexpr auto registration = kapi::devices::kernel_driver<descriptor>{};
+
     struct null_node final : kapi::filesystem::character_special_file
     {
     public:
diff --git a/kernel/kernel/drivers/pseudo/zero.cpp b/kernel/kernel/drivers/pseudo/zero.cpp
index 550a97ff..724ff25c 100644
--- a/kernel/kernel/drivers/pseudo/zero.cpp
+++ b/kernel/kernel/drivers/pseudo/zero.cpp
@@ -27,6 +27,23 @@ namespace kernel::drivers::pseudo
 
   namespace
   {
+    struct descriptor final : kapi::devices::driver_descriptor
+    {
+    public:
+      [[nodiscard("")]] auto name() const noexcept -> std::string_view override
+      {
+        return "dev_zero";
+      }
+
+      [[nodiscard("")]] auto make_instance() const -> kstd::shared_ptr<kapi::devices::driver> override
+      {
+        return kstd::make_shared<zero>();
+      }
+    };
+
+    [[gnu::used]]
+    constexpr auto registration = kapi::devices::kernel_driver<descriptor>{};
+
     struct zero_node final : kapi::filesystem::character_special_file
     {
     public:
diff --git a/kernel/kernel/drivers/storage/ram_disk.cpp b/kernel/kernel/drivers/storage/ram_disk.cpp
index 987f4bbc..f7e73cd1 100644
--- a/kernel/kernel/drivers/storage/ram_disk.cpp
+++ b/kernel/kernel/drivers/storage/ram_disk.cpp
@@ -31,6 +31,23 @@ namespace kernel::drivers::storage
   {
     constexpr auto default_block_size = 512_B;
 
+    struct descriptor final : kapi::devices::driver_descriptor
+    {
+    public:
+      [[nodiscard("")]] auto name() const noexcept -> std::string_view override
+      {
+        return "ram_disk";
+      }
+
+      [[nodiscard("")]] auto make_instance() const -> kstd::shared_ptr<kapi::devices::driver> override
+      {
+        return kstd::make_shared<ram_disk>();
+      }
+    };
+
+    [[gnu::used]]
+    constexpr auto registration = kapi::devices::kernel_driver<descriptor>{};
+
     struct block_node final : kapi::filesystem::block_special_file
     {
       explicit block_node(kapi::boot_modules::module const & module)