kernel: generalize CPU discovery

3 files changed, 71 insertions, 13 deletions

diff --git a/arch/x86_64/CMakeLists.txt b/arch/x86_64/CMakeLists.txt
index 62a2aad..87cb98c 100644
--- a/arch/x86_64/CMakeLists.txt
+++ b/arch/x86_64/CMakeLists.txt
@@ -19,6 +19,7 @@ target_sources("x86_64" PRIVATE
     "kapi/devices.cpp"
     "kapi/interrupts.cpp"
     "kapi/memory.cpp"
+    "kapi/platform.cpp"
     "kapi/system.cpp"
 
     # CPU Initialization
diff --git a/arch/x86_64/kapi/acpi.cpp b/arch/x86_64/kapi/acpi.cpp
index 9766154..ec38aee 100644
--- a/arch/x86_64/kapi/acpi.cpp
+++ b/arch/x86_64/kapi/acpi.cpp
@@ -1,16 +1,9 @@
 #include "kapi/acpi.hpp"
 
-#include "kapi/devices.hpp"
-#include "kapi/memory.hpp"
-
 #include "arch/boot/boot.hpp"
-#include "arch/devices/local_apic.hpp"
 
 #include <kstd/memory>
 
-#include <cstddef>
-#include <cstdint>
-
 namespace kapi::acpi
 {
 
@@ -34,10 +27,4 @@ namespace kapi::acpi
     return kstd::make_observer(system_description_pointer);
   }
 
-  auto create_local_interrupt_controller(std::size_t major, std::size_t minor, std::uint64_t hardware_id,
-                                         memory::physical_address address) -> kstd::unique_ptr<devices::device>
-  {
-    return kstd::make_unique<arch::devices::local_apic>(major, minor, hardware_id, address);
-  }
-
 }  // namespace kapi::acpi
\ No newline at end of file
diff --git a/arch/x86_64/kapi/platform.cpp b/arch/x86_64/kapi/platform.cpp
new file mode 100644
index 0000000..2e7c7e4
--- /dev/null
+++ b/arch/x86_64/kapi/platform.cpp
@@ -0,0 +1,70 @@
+#include "kapi/platform.hpp"
+
+#include "kapi/acpi.hpp"
+#include "kapi/devices.hpp"
+#include "kapi/memory.hpp"
+
+#include "arch/devices/local_apic.hpp"
+
+#include <kstd/memory>
+#include <kstd/print>
+
+#include <cstddef>
+#include <cstdint>
+
+namespace kapi::platform
+{
+
+  namespace
+  {
+    constexpr auto default_lapic_address = kapi::memory::physical_address{0xFEE0'0000};
+  }
+
+  auto discover_cpu_topology(kapi::devices::bus & bus) -> bool
+  {
+    auto madt = kapi::acpi::get_table("APIC");
+    if (!madt)
+    {
+      kstd::println("[x86_64:PLT] Failed to find ACPI APIC table");
+      return false;
+    }
+
+    auto const * current = reinterpret_cast<std::byte const *>(madt.get()) + sizeof(kapi::acpi::madt_header);
+    auto const * end = reinterpret_cast<std::byte const *>(madt.get()) + madt->length();
+
+    auto bsp_found = false;
+    auto core_count = 0uz;
+
+    while (current < end)
+    {
+      auto const * sub_table = reinterpret_cast<kapi::acpi::madt_subtable_header const *>(current);
+      if (sub_table->type() == 0)
+      {
+        auto const * local_apic = reinterpret_cast<kapi::acpi::madt_local_apic const *>(sub_table);
+        if (local_apic->flags() & 0b11)
+        {
+          auto is_bsp = !bsp_found;
+          bsp_found = true;
+
+          if (kapi::platform::cpu_detected(bus, local_apic->processor_id(), is_bsp))
+          {
+            ++core_count;
+          }
+        }
+      }
+
+      current += sub_table->length();
+    }
+
+    kstd::println("[x86_64:PLT] Found {} CPU cores", core_count);
+
+    return core_count > 0;
+  }
+
+  auto create_core_interrupt_controller(std::size_t major, std::size_t minor, std::uint64_t hardware_id)
+      -> kstd::unique_ptr<devices::device>
+  {
+    return kstd::make_unique<arch::devices::local_apic>(major, minor, hardware_id, default_lapic_address);
+  }
+
+}  // namespace kapi::platform
\ No newline at end of file