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, 158 insertions, 0 deletions

diff --git a/kernel/src/acpi/manager.cpp b/kernel/src/acpi/manager.cpp
new file mode 100644
index 0000000..300b85e
--- /dev/null
+++ b/kernel/src/acpi/manager.cpp
@@ -0,0 +1,103 @@
+#include "kernel/acpi/manager.hpp"
+
+#include "kapi/acpi.hpp"
+#include "kapi/memory.hpp"
+#include "kapi/system.hpp"
+
+#include <kstd/memory>
+#include <kstd/print>
+
+#include <cstddef>
+#include <cstdint>
+#include <string_view>
+
+namespace kernel::acpi
+{
+
+  manager::manager(kapi::acpi::root_system_description_pointer const & sdp)
+      : m_sdp{&sdp}
+  {
+    if (m_sdp->signature() != "RSD PTR ")
+    {
+      kapi::system::panic("[OS:ACPI] Invalid RSDP signature!");
+    }
+
+    if (m_sdp->revision() >= 2)
+    {
+      auto const xsdp = static_cast<kapi::acpi::extended_system_description_pointer const *>(m_sdp);
+      if (!xsdp->validate())
+      {
+        kapi::system::panic("[OS:ACPI] Invalid XSDP signature!");
+      }
+      auto physical_extended_table_address = xsdp->table_address();
+      auto linear_extended_table_address = kapi::memory::hhdm_to_linear(physical_extended_table_address);
+      m_rsdt = static_cast<kapi::acpi::system_description_table_header const *>(linear_extended_table_address);
+      m_extended = true;
+    }
+    else
+    {
+      if (!m_sdp->validate())
+      {
+        kapi::system::panic("[OS:ACPI] Invalid RSDP checksum!");
+      }
+      auto physical_root_table_address = m_sdp->table_address();
+      auto linear_root_table_address = kapi::memory::hhdm_to_linear(physical_root_table_address);
+      m_rsdt = static_cast<kapi::acpi::system_description_table_header const *>(linear_root_table_address);
+    }
+  }
+
+  auto manager::load_tables() -> bool
+  {
+    if (!kapi::acpi::validate_checksum({reinterpret_cast<std::byte const *>(m_rsdt), m_rsdt->length().value}))
+    {
+      kapi::system::panic("[OS:ACPI] Invalid RSDT checksum!");
+    }
+
+    auto entry_size = m_extended ? sizeof(std::uint64_t) : sizeof(std::uint32_t);
+    auto entry_count = (m_rsdt->length().value - sizeof(kapi::acpi::system_description_table_header)) / entry_size;
+    auto entries_base =
+        reinterpret_cast<std::byte const *>(m_rsdt) + sizeof(kapi::acpi::system_description_table_header);
+
+    for (std::size_t i = 0; i < entry_count; ++i)
+    {
+      auto physical_table_address = kapi::memory::physical_address{};
+
+      if (m_extended)
+      {
+        auto entry = reinterpret_cast<std::uint64_t const *>(entries_base + (i * entry_size));
+        physical_table_address = kapi::memory::physical_address{*entry};
+      }
+      else
+      {
+        auto entry = reinterpret_cast<std::uint32_t const *>(entries_base + (i * entry_size));
+        physical_table_address = kapi::memory::physical_address{*entry};
+      }
+
+      auto linear_table_address = kapi::memory::hhdm_to_linear(physical_table_address);
+      auto table = static_cast<kapi::acpi::system_description_table_header const *>(linear_table_address);
+
+      if (!kapi::acpi::validate_checksum({reinterpret_cast<std::byte const *>(table), table->length().value}))
+      {
+        kstd::println(kstd::print_sink::stderr, "[OS:ACPI] Invalid table checksum!");
+      }
+      else
+      {
+        kstd::println("[OS:ACPI] Found '{}' ACPI table", table->signature());
+        m_tables.emplace(table->signature(), table);
+      }
+    }
+
+    return !m_tables.empty();
+  }
+
+  auto manager::get_table(std::string_view signature)
+      -> kstd::observer_ptr<kapi::acpi::system_description_table_header const>
+  {
+    if (m_tables.contains(signature))
+    {
+      return kstd::make_observer(m_tables.at(signature));
+    }
+    return nullptr;
+  }
+
+}  // namespace kernel::acpi
diff --git a/kernel/src/devices/cpu.cpp b/kernel/src/devices/cpu.cpp
new file mode 100644
index 0000000..eb10d74
--- /dev/null
+++ b/kernel/src/devices/cpu.cpp
@@ -0,0 +1,45 @@
+#include "kernel/devices/cpu.hpp"
+
+#include "kapi/devices.hpp"
+#include "kapi/platform.hpp"
+
+#include <kstd/print>
+
+#include <cstddef>
+#include <cstdint>
+
+namespace kernel::devices
+{
+
+  cpu::core::core(std::size_t major_number, std::size_t minor_number, std::uint64_t hardware_id, bool is_bsp)
+      : kapi::devices::bus{major_number, minor_number, "cpu_core"}
+      , m_hardware_id{hardware_id}
+      , m_is_bsp{is_bsp}
+  {}
+
+  auto cpu::core::hardware_id() const -> std::uint64_t
+  {
+    return m_hardware_id;
+  }
+
+  auto cpu::core::is_bsp() const -> bool
+  {
+    return m_is_bsp;
+  }
+
+  cpu::cpu(std::size_t major_number)
+      : kapi::devices::bus{major_number, 0, "cpu"}
+  {}
+
+  auto cpu::probe() -> bool
+  {
+    if (!kapi::platform::discover_cpu_topology(*this))
+    {
+      kstd::println("[OS:DEV] Failed to discover CPU topology");
+      return false;
+    }
+
+    return true;
+  }
+
+}  // namespace kernel::devices
\ No newline at end of file
diff --git a/kernel/src/main.cpp b/kernel/src/main.cpp
index 2eaa2d8..e704955 100644
--- a/kernel/src/main.cpp
+++ b/kernel/src/main.cpp
@@ -1,3 +1,4 @@
+#include "kapi/acpi.hpp"
 #include "kapi/boot_modules.hpp"
 #include "kapi/cio.hpp"
 #include "kapi/cpu.hpp"
@@ -179,6 +180,15 @@ auto main() -> int
   kstd::println("[OS] Memory subsystem initialized.");
   kapi::system::memory_initialized();
 
+  auto acpi_root_pointer = kapi::acpi::get_root_pointer();
+  if (acpi_root_pointer && acpi_root_pointer->validate())
+  {
+    if (kapi::acpi::init(*acpi_root_pointer))
+    {
+      kstd::println("[OS] ACPI subsystem initialized.");
+    }
+  }
+
   kapi::devices::init();
   kstd::println("[OS] System root bus initialized.");