Merge branch 'fmorgner/develop-BA-FS26/apci' into develop-BA-FS26

This patchset introduces basic support for ACPI. Currently, the only
user of that support is the CPU discovery subsystem. It uses the
processed ACPI information to initialize CPU core devices and their
associated local APICs.

8 files changed, 213 insertions, 24 deletions

diff --git a/arch/x86_64/CMakeLists.txt b/arch/x86_64/CMakeLists.txt
index 83cae0b..87cb98c 100644
--- a/arch/x86_64/CMakeLists.txt
+++ b/arch/x86_64/CMakeLists.txt
@@ -12,12 +12,14 @@ target_link_libraries("x86_64" PUBLIC
 
 target_sources("x86_64" PRIVATE
     # Platform-dependent KAPI implementation
+    "kapi/acpi.cpp"
     "kapi/boot_modules.cpp"
     "kapi/cio.cpp"
     "kapi/cpu.cpp"
     "kapi/devices.cpp"
     "kapi/interrupts.cpp"
     "kapi/memory.cpp"
+    "kapi/platform.cpp"
     "kapi/system.cpp"
 
     # CPU Initialization
@@ -38,7 +40,9 @@ target_sources("x86_64" PRIVATE
     "src/debug/qemu_output.cpp"
 
     # Devices
+    "src/devices/init.cpp"
     "src/devices/legacy_pit.cpp"
+    "src/devices/local_apic.cpp"
 
     # Memory management
     "src/memory/kernel_mapper.cpp"
diff --git a/arch/x86_64/include/arch/devices/init.hpp b/arch/x86_64/include/arch/devices/init.hpp
new file mode 100644
index 0000000..c5fbf37
--- /dev/null
+++ b/arch/x86_64/include/arch/devices/init.hpp
@@ -0,0 +1,12 @@
+#ifndef TEACHOS_ARCH_X86_64_DEVICES_INIT_HPP
+#define TEACHOS_ARCH_X86_64_DEVICES_INIT_HPP
+
+namespace arch::devices
+{
+
+  auto init_acpi_devices() -> void;
+  auto init_legacy_devices() -> void;
+
+}  // namespace arch::devices
+
+#endif
\ No newline at end of file
diff --git a/arch/x86_64/include/arch/devices/local_apic.hpp b/arch/x86_64/include/arch/devices/local_apic.hpp
new file mode 100644
index 0000000..71e9758
--- /dev/null
+++ b/arch/x86_64/include/arch/devices/local_apic.hpp
@@ -0,0 +1,26 @@
+#ifndef TEACHOS_ARCH_X86_64_DEVICES_LOCAL_APIC_HPP
+#define TEACHOS_ARCH_X86_64_DEVICES_LOCAL_APIC_HPP
+
+#include "kapi/devices/device.hpp"
+#include "kapi/memory.hpp"
+
+#include <cstddef>
+#include <cstdint>
+
+namespace arch::devices
+{
+
+  struct local_apic : kapi::devices::device
+  {
+    local_apic(std::size_t major, std::size_t minor, std::uint64_t hardware_id, kapi::memory::physical_address base);
+
+    auto init() -> bool override;
+
+  private:
+    std::uint64_t m_hardware_id{};
+    kapi::memory::physical_address m_base{};
+  };
+
+}  // namespace arch::devices
+
+#endif
\ No newline at end of file
diff --git a/arch/x86_64/kapi/acpi.cpp b/arch/x86_64/kapi/acpi.cpp
new file mode 100644
index 0000000..ec38aee
--- /dev/null
+++ b/arch/x86_64/kapi/acpi.cpp
@@ -0,0 +1,30 @@
+#include "kapi/acpi.hpp"
+
+#include "arch/boot/boot.hpp"
+
+#include <kstd/memory>
+
+namespace kapi::acpi
+{
+
+  auto get_root_pointer() -> kstd::observer_ptr<root_system_description_pointer const>
+  {
+    auto const & mbi = kapi::boot::bootstrap_information.mbi;
+    auto system_description_pointer = static_cast<kapi::acpi::root_system_description_pointer const *>(nullptr);
+
+    if (auto const & xsdp = mbi->maybe_acpi_xsdp())
+    {
+      auto data = xsdp->pointer().data();
+
+      system_description_pointer = reinterpret_cast<kapi::acpi::root_system_description_pointer const *>(data);
+    }
+    else if (auto const & rsdp = mbi->maybe_acpi_rsdp())
+    {
+      auto data = rsdp->pointer().data();
+      system_description_pointer = reinterpret_cast<kapi::acpi::root_system_description_pointer const *>(data);
+    }
+
+    return kstd::make_observer(system_description_pointer);
+  }
+
+}  // namespace kapi::acpi
\ No newline at end of file
diff --git a/arch/x86_64/kapi/devices.cpp b/arch/x86_64/kapi/devices.cpp
index b15503d..47c7f8c 100644
--- a/arch/x86_64/kapi/devices.cpp
+++ b/arch/x86_64/kapi/devices.cpp
@@ -1,35 +1,14 @@
 #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>
+#include "arch/devices/init.hpp"
 
 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_major_number = kapi::devices::allocate_major_number();
-    auto isa_bus = kstd::make_unique<arch::bus::isa>(isa_major_number);
-
-    auto pit_major_number = kapi::devices::allocate_major_number();
-    auto pit = kstd::make_unique<arch::devices::legacy_pit>(pit_major_number, 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));
+    arch::devices::init_acpi_devices();
+    arch::devices::init_legacy_devices();
   }
 
 }  // namespace kapi::devices
\ 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..380fc66
--- /dev/null
+++ b/arch/x86_64/kapi/platform.cpp
@@ -0,0 +1,71 @@
+#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 <utility>
+
+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 static const core_major = kapi::devices::allocate_major_number();
+    auto static const interrupt_controller_major = kapi::devices::allocate_major_number();
+    auto static core_index = 0uz;
+
+    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;
+
+          auto lapic = kstd::make_unique<arch::devices::local_apic>(interrupt_controller_major, core_index,
+                                                                    local_apic->apic_id(), default_lapic_address);
+          if (kapi::platform::cpu_detected(bus, core_major, core_index, local_apic->processor_id(), is_bsp,
+                                           std::move(lapic)))
+          {
+            ++core_count;
+          }
+        }
+      }
+
+      current += sub_table->length();
+    }
+
+    kstd::println("[x86_64:PLT] Found {} CPU cores", core_count);
+
+    return core_count > 0;
+  }
+
+}  // namespace kapi::platform
\ No newline at end of file
diff --git a/arch/x86_64/src/devices/init.cpp b/arch/x86_64/src/devices/init.cpp
new file mode 100644
index 0000000..6cba986
--- /dev/null
+++ b/arch/x86_64/src/devices/init.cpp
@@ -0,0 +1,39 @@
+#include "arch/devices/init.hpp"
+
+#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 arch::devices
+{
+
+  namespace
+  {
+    constexpr auto pit_frequency_in_hz = std::uint32_t{100u};
+  }
+
+  auto init_acpi_devices() -> void {}
+
+  auto init_legacy_devices() -> void
+  {
+    kstd::println("[x86_64:DEV] Initializing ISA bus...");
+
+    auto isa_major_number = kapi::devices::allocate_major_number();
+    auto isa_bus = kstd::make_unique<arch::bus::isa>(isa_major_number);
+
+    auto pit_major_number = kapi::devices::allocate_major_number();
+    auto pit = kstd::make_unique<arch::devices::legacy_pit>(pit_major_number, pit_frequency_in_hz);
+    isa_bus->add_child(std::move(pit));
+
+    auto & root_bus = kapi::devices::get_root_bus();
+    root_bus.add_child(std::move(isa_bus));
+  }
+
+}  // namespace arch::devices
diff --git a/arch/x86_64/src/devices/local_apic.cpp b/arch/x86_64/src/devices/local_apic.cpp
new file mode 100644
index 0000000..beb75ef
--- /dev/null
+++ b/arch/x86_64/src/devices/local_apic.cpp
@@ -0,0 +1,28 @@
+#include "arch/devices/local_apic.hpp"
+
+#include "kapi/devices.hpp"
+#include "kapi/memory.hpp"
+
+#include <kstd/print>
+
+#include <cstddef>
+#include <cstdint>
+
+namespace arch::devices
+{
+
+  local_apic::local_apic(std::size_t major, std::size_t minor, std::uint64_t hardware_id,
+                         kapi::memory::physical_address base)
+      : kapi::devices::device{major, minor, "lapic"}
+      , m_hardware_id{hardware_id}
+      , m_base{base}
+  {}
+
+  auto local_apic::init() -> bool
+  {
+    kstd::println("[x86_64:DEV] Initializing local APIC on core {}", m_hardware_id);
+
+    return true;
+  }
+
+}  // namespace arch::devices
\ No newline at end of file