1 files changed, 230 insertions, 0 deletions
diff --git a/kernel/kapi/devices/driver.tests.cpp b/kernel/kapi/devices/driver.tests.cpp
new file mode 100644
index 00000000..abce92d2
--- /dev/null
+++ b/kernel/kapi/devices/driver.tests.cpp
@@ -0,0 +1,230 @@
+#include <kapi/devices.hpp>
+
+#include <kstd/memory.hpp>
+#include <kstd/result.hpp>
+#include <kstd/string.hpp>
+
+#include <catch2/catch_test_macros.hpp>
+
+#include <algorithm>
+#include <array>
+#include <cstdint>
+#include <span>
+#include <string_view>
+
+namespace
+{
+  struct controller_identification
+  {
+    constexpr auto static id = kapi::devices::interface{"stacking_test_controller_identification"};
+    virtual ~controller_identification() = default;
+    [[nodiscard]] virtual auto controller_name() const -> std::string_view = 0;
+  };
+
+  struct controller_driver_identification
+  {
+    constexpr auto static id = kapi::devices::interface{"stacking_test_controller_driver_identification"};
+    virtual ~controller_driver_identification() = default;
+    [[nodiscard]] virtual auto supported_names() const -> std::span<std::string_view const> = 0;
+  };
+
+  struct controller_bus final : kapi::devices::bus, kapi::devices::bus_protocol
+  {
+    using kapi::devices::bus::bus;
+
+    auto enumerate(kapi::devices::bus &) -> void override {}
+
+    [[nodiscard]] auto match(kapi::devices::device const & dev, kapi::devices::driver const & drv) const
+        -> kstd::result<std::uint32_t> override
+    {
+      auto const * ident = dev.as<controller_identification>();
+      auto const * claims = drv.as<controller_driver_identification>();
+      if (!ident || !claims || !std::ranges::contains(claims->supported_names(), ident->controller_name()))
+      {
+        return kstd::failure(kapi::devices::driver_match_errc::no_match);
+      }
+      return 0u;
+    }
+
+    [[nodiscard]] auto protocol() -> kapi::devices::bus_protocol * override
+    {
+      return this;
+    }
+  };
+
+  struct controller_device final : kapi::devices::bus, controller_identification
+  {
+    controller_device()
+        : kapi::devices::bus{"stacking_test_controller"}
+    {}
+
+    [[nodiscard]] auto controller_name() const -> std::string_view override
+    {
+      return "stacking_test_controller";
+    }
+
+  protected:
+    auto query_interface(kapi::devices::interface interface) -> void * override
+    {
+      if (interface == controller_identification::id)
+      {
+        return static_cast<controller_identification *>(this);
+      }
+      return kapi::devices::bus::query_interface(interface);
+    }
+  };
+
+  struct leaf_identification
+  {
+    constexpr kapi::devices::interface static id{"stacking_test_leaf_identification"};
+    virtual ~leaf_identification() = default;
+    [[nodiscard]] virtual auto leaf_name() const -> std::string_view = 0;
+  };
+
+  struct leaf_driver_identification
+  {
+    constexpr kapi::devices::interface static id{"stacking_test_leaf_driver_identification"};
+    virtual ~leaf_driver_identification() = default;
+    [[nodiscard]] virtual auto supported_names() const -> std::span<std::string_view const> = 0;
+  };
+
+  struct leaf_device final : kapi::devices::device, leaf_identification
+  {
+    leaf_device()
+        : kapi::devices::device{"stacking_test_leaf"}
+    {}
+
+    [[nodiscard]] auto leaf_name() const -> std::string_view override
+    {
+      return "stacking_test_leaf";
+    }
+
+  protected:
+    auto query_interface(kapi::devices::interface interface) -> void * override
+    {
+      if (interface == leaf_identification::id)
+      {
+        return static_cast<leaf_identification *>(this);
+      }
+      return kapi::devices::device::query_interface(interface);
+    }
+  };
+
+  struct leaf_bus final : kapi::devices::bus, kapi::devices::bus_protocol
+  {
+    using kapi::devices::bus::bus;
+
+    auto enumerate(kapi::devices::bus & self) -> void override
+    {
+      self.add_child(kstd::make_shared<leaf_device>());
+    }
+
+    [[nodiscard]] auto match(kapi::devices::device const & dev, kapi::devices::driver const & drv) const
+        -> kstd::result<std::uint32_t> override
+    {
+      auto const * ident = dev.as<leaf_identification>();
+      auto const * claims = drv.as<leaf_driver_identification>();
+      if (!ident || !claims || !std::ranges::contains(claims->supported_names(), ident->leaf_name()))
+      {
+        return kstd::failure(kapi::devices::driver_match_errc::no_match);
+      }
+      return 0u;
+    }
+
+    [[nodiscard]] auto protocol() -> kapi::devices::bus_protocol * override
+    {
+      return this;
+    }
+  };
+
+  struct controller_driver final : kapi::devices::driver, controller_driver_identification
+  {
+    [[nodiscard]] auto probe(kapi::devices::device & dev) -> kstd::result<void> override
+    {
+      auto self_as_bus = kstd::static_pointer_cast<kapi::devices::bus>(dev.shared_from_this());
+      auto leaf = kstd::make_shared<leaf_bus>("stacking_test_leaf_bus");
+      self_as_bus->add_child(leaf);
+      leaf->enumerate(*leaf);
+
+      return kstd::success();
+    }
+
+    auto unbind(kapi::devices::device &) -> void override {}
+
+    [[nodiscard]] auto supported_names() const -> std::span<std::string_view const> override
+    {
+      constexpr auto static names = std::array<std::string_view, 1>{"stacking_test_controller"};
+      return names;
+    }
+
+  protected:
+    auto query_interface(kapi::devices::interface interface) -> void * override
+    {
+      if (interface == controller_driver_identification::id)
+      {
+        return static_cast<controller_driver_identification *>(this);
+      }
+
+      return kapi::devices::driver::query_interface(interface);
+    }
+  };
+
+  struct leaf_driver final : kapi::devices::driver, leaf_driver_identification
+  {
+    [[nodiscard]] auto probe(kapi::devices::device &) -> kstd::result<void> override
+    {
+      return kstd::success();
+    }
+
+    auto unbind(kapi::devices::device &) -> void override {}
+
+    [[nodiscard]] auto supported_names() const -> std::span<std::string_view const> override
+    {
+      constexpr auto static names = std::array<std::string_view, 1>{"stacking_test_leaf"};
+      return names;
+    }
+
+  protected:
+    auto query_interface(kapi::devices::interface interface) -> void * override
+    {
+      if (interface == leaf_driver_identification::id)
+      {
+        return static_cast<leaf_driver_identification *>(this);
+      }
+
+      return kapi::devices::driver::query_interface(interface);
+    }
+  };
+}  // namespace
+
+SCENARIO("a bound controller driver can attach a further, independently-typed bus protocol of its own",
+         "[devices][driver][stacking]")
+{
+  GIVEN("a controller bus, a controller driver, and a leaf driver, none aware of each other's identification scheme")
+  {
+    auto outer_bus = kstd::make_shared<controller_bus>("stacking_test_controller_bus");
+
+    kapi::devices::driver_registry::get().add(kstd::make_shared<controller_driver>());
+    kapi::devices::driver_registry::get().add(kstd::make_shared<leaf_driver>());
+
+    WHEN("the controller device is attached to the controller bus")
+    {
+      outer_bus->add_child(kstd::make_shared<controller_device>());
+
+      THEN("the controller device bound the controller driver")
+      {
+        auto controller = kapi::devices::find_device("stacking_test_controller");
+        REQUIRE(controller != nullptr);
+        REQUIRE(controller->state() == kapi::devices::state::bound);
+      }
+
+      THEN("the leaf device the controller driver attached is reachable and bound to the leaf driver")
+      {
+        auto leaf = kapi::devices::find_device("stacking_test_leaf");
+        REQUIRE(leaf != nullptr);
+        REQUIRE(leaf->state() == kapi::devices::state::bound);
+        REQUIRE(leaf->bound_driver() != nullptr);
+      }
+    }
+  }
+}