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.

3 files changed, 104 insertions, 24 deletions

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