From 526709a1e86d55dd88e2dbdbc471795efce9046b Mon Sep 17 00:00:00 2001
From: Felix Morgner <felix.morgner@ost.ch>
Date: Thu, 23 Jul 2026 01:38:56 +0200
Subject: kapi: bootstrap owning device tree

---
 kernel/kapi/devices.cpp        | 56 +++++++++++++++++++++++++++---------------
 kernel/kapi/devices/bus.cpp    | 20 ++++++++-------
 kernel/kapi/devices/device.cpp |  9 +++++--
 3 files changed, 54 insertions(+), 31 deletions(-)

(limited to 'kernel/kapi')

diff --git a/kernel/kapi/devices.cpp b/kernel/kapi/devices.cpp
index 6da503d9..8f3011fe 100644
--- a/kernel/kapi/devices.cpp
+++ b/kernel/kapi/devices.cpp
@@ -10,7 +10,6 @@
 #include <kstd/print.hpp>
 #include <kstd/string.hpp>
 
-#include <optional>
 #include <string_view>
 #include <utility>
 
@@ -18,37 +17,55 @@ namespace kapi::devices
 {
   namespace
   {
-    auto constinit root_bus = std::optional<kernel::devices::root_bus>{};
-    auto constinit device_tree = kstd::flat_map<kstd::string, kstd::observer_ptr<device>>{};
+    auto constinit root_bus = kstd::shared_ptr<kernel::devices::root_bus>{};
+    auto constinit device_tree = kstd::flat_map<kstd::string, kstd::weak_ptr<device>>{};
   }  // namespace
 
   auto init() -> void
   {
-    if (root_bus.has_value())
+    if (root_bus)
     {
       kapi::system::panic("[OS:DEV] The device subsystem has already been initialized");
     }
 
     interface_registry::init();
 
-    auto & bus = root_bus.emplace();
-    register_device(bus);
-    bus.init();
+    root_bus = kstd::make_shared<kernel::devices::root_bus>();
+    register_device(root_bus);
+    root_bus->init();
   }
 
-  auto get_root_bus() -> bus &
+  auto get_root_bus() -> kstd::shared_ptr<bus>
   {
-    if (!root_bus.has_value())
+    if (!root_bus)
     {
       kapi::system::panic("[OS:DEV] Root bus not initialized!");
     }
-    return *root_bus;
+    return root_bus;
   }
 
-  auto register_device(device & device) -> bool
+  auto register_device(kstd::shared_ptr<device> device) -> bool
   {
-    kstd::println("[OS:DEV] Registering device {}", device.name());
-    return device_tree.emplace(device.name(), &device).second;
+    if (!device)
+    {
+      return false;
+    }
+
+    kstd::println("[OS:DEV] Registering device {}", device->name());
+
+    auto found = device_tree.find(device->name());
+    if (found != device_tree.end())
+    {
+      if (!found->second.expired())
+      {
+        return false;
+      }
+
+      found->second = device;
+      return true;
+    }
+
+    return device_tree.emplace(device->name(), device).second;
   }
 
   auto unregister_device(device &) -> bool
@@ -57,16 +74,15 @@ namespace kapi::devices
     return false;
   }
 
-  auto find_device(std::string_view name) -> kstd::observer_ptr<device>
+  auto find_device(std::string_view name) -> kstd::shared_ptr<device>
   {
-    for (auto const & [key, value] : device_tree)
+    auto found = device_tree.find(kstd::string{name});
+    if (found == device_tree.end())
     {
-      if (value->name() == name)
-      {
-        return value;
-      }
+      return nullptr;
     }
-    return nullptr;
+
+    return found->second.lock();
   }
 
 }  // namespace kapi::devices
diff --git a/kernel/kapi/devices/bus.cpp b/kernel/kapi/devices/bus.cpp
index d9f3f991..179a04a8 100644
--- a/kernel/kapi/devices/bus.cpp
+++ b/kernel/kapi/devices/bus.cpp
@@ -9,6 +9,7 @@
 #include <kstd/vector.hpp>
 
 #include <algorithm>
+#include <span>
 #include <utility>
 
 namespace kapi::devices
@@ -41,29 +42,30 @@ namespace kapi::devices
     return child_status;
   }
 
-  auto bus::add_child(kstd::unique_ptr<device> child) -> void
+  auto bus::add_child(kstd::shared_ptr<device> child) -> void
   {
-    auto observer = m_observers.emplace_back(child.get());
-    child->set_parent(kstd::make_observer(this));
-    m_devices.push_back(std::move(child));
-    if (!kapi::devices::register_device(*observer))
+    child->set_parent(kstd::static_pointer_cast<bus>(shared_from_this()));
+
+    if (!kapi::devices::register_device(child))
     {
       kapi::system::panic("[OS:DEV] Failed to register child device");
     }
 
+    auto & attached = m_devices.emplace_back(std::move(child));
+
     if (m_initialized.test())
     {
-      kstd::println("[OS:DEV] Initializing child device {}@{}", observer->name(), name());
-      if (!observer->init())
+      kstd::println("[OS:DEV] Initializing child device {}@{}", attached->name(), name());
+      if (!attached->init())
       {
         kapi::system::panic("[OS:DEV] Failed to initialize child device");
       }
     }
   }
 
-  [[nodiscard]] auto bus::children() const -> kstd::vector<kstd::observer_ptr<device>> const &
+  [[nodiscard]] auto bus::children() const -> std::span<kstd::shared_ptr<device> const>
   {
-    return m_observers;
+    return {m_devices.data(), m_devices.size()};
   }
 
   auto bus::enumerate() -> bool
diff --git a/kernel/kapi/devices/device.cpp b/kernel/kapi/devices/device.cpp
index 0d00d8fd..540d37b7 100644
--- a/kernel/kapi/devices/device.cpp
+++ b/kernel/kapi/devices/device.cpp
@@ -12,12 +12,17 @@ namespace kapi::devices
       : m_name(name)
   {}
 
-  [[nodiscard]] auto device::name() const -> kstd::string const &
+  auto device::name() const -> kstd::string const &
   {
     return m_name;
   }
 
-  auto device::set_parent(kstd::observer_ptr<bus> parent) -> void
+  auto device::parent() const -> kstd::shared_ptr<bus>
+  {
+    return m_parent.lock();
+  }
+
+  auto device::set_parent(kstd::weak_ptr<bus> parent) -> void
   {
     m_parent = parent;
   }
-- 
cgit v1.2.3