kapi: hook ACPI initialization up to boot process

8 files changed, 186 insertions, 21 deletions

diff --git a/.vscode/settings.json b/.vscode/settings.json
index 4271526..6ea3c79 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -32,6 +32,7 @@
         "crtp",
         "efer",
         "functors",
+        "hhdm",
         "idtr",
         "initializable",
         "interprocedural",
@@ -43,6 +44,7 @@
         "malloc",
         "memcmp",
         "memset",
+        "mmio",
         "multiboot",
         "nodiscard",
         "nolintnextline",
@@ -51,12 +53,14 @@
         "raii",
         "rdmsr",
         "RSDP",
+        "rsdt",
         "rvalues",
         "stringview",
         "sysret",
         "teachos",
         "undelegated",
-        "wrmsr"
+        "wrmsr",
+        "xsdp"
     ],
     "testMate.cpp.debug.configTemplate": {
         "type": "cppdbg",
diff --git a/arch/x86_64/kapi/devices.cpp b/arch/x86_64/kapi/devices.cpp
index b15503d..e1773e7 100644
--- a/arch/x86_64/kapi/devices.cpp
+++ b/arch/x86_64/kapi/devices.cpp
@@ -1,5 +1,9 @@
 #include "kapi/devices.hpp"
 
+#include "kapi/acpi.hpp"
+#include "kapi/boot.hpp"
+
+#include "arch/boot/boot.hpp"
 #include "arch/bus/isa.hpp"
 #include "arch/devices/legacy_pit.hpp"
 
@@ -19,7 +23,33 @@ namespace kapi::devices
 
   auto init_platform_devices() -> void
   {
-    kstd::println("[x86_64:devices] Initializing ISA bus...");
+    auto const & mbi = boot::bootstrap_information.mbi;
+    auto system_description_pointer = static_cast<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);
+    }
+
+    if (system_description_pointer)
+    {
+      if (!kapi::acpi::init(*system_description_pointer))
+      {
+        kstd::println(kstd::print_sink::stderr, "[x86_64:DEV] ACPI initialization failed. No tables loaded.");
+      }
+    }
+    else
+    {
+      kstd::println(kstd::print_sink::stderr, "[x86_64:DEV] No ACPI RSDP found. Most devices will not be available.");
+    }
+
+    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);
diff --git a/kapi/include/kapi/acpi.hpp b/kapi/include/kapi/acpi.hpp
index 1068921..d5e3c87 100644
--- a/kapi/include/kapi/acpi.hpp
+++ b/kapi/include/kapi/acpi.hpp
@@ -2,16 +2,36 @@
 #define TEACHOS_KAPI_ACPI_HPP
 
 #include "kapi/memory.hpp"
+
 #include <kstd/units>
 
 #include <array>
 #include <cstddef>
 #include <cstdint>
+#include <span>
 #include <string_view>
 
 namespace kapi::acpi
 {
 
+  //! @addtogroup kapi-acpi
+  //! @{
+
+  struct [[gnu::packed]] system_description_table_header
+  {
+    std::array<char, 4> signature;
+    std::uint32_t length;
+    std::uint8_t revision;
+    std::uint8_t checksum;
+    std::array<char, 6> oem_id;
+    std::array<char, 8> oem_table_id;
+    std::uint32_t oem_revision;
+    std::uint32_t creator_id;
+    std::uint32_t create_revision;
+  };
+
+  //! @}
+
   //! @addtogroup kapi-acpi-kernel-defined
   //! @{
 
@@ -44,20 +64,18 @@ namespace kapi::acpi
     [[maybe_unused]] std::array<std::byte, 3> m_reserved;
   };
 
-  //! @}
+  //! Initialize the ACPI subsystem and discover the available tables.
+  //!
+  //! @return true iff. a valid system description tabled was found, false otherwise.
+  auto init(root_system_description_pointer const & sdp) -> bool;
 
-  struct [[gnu::packed]] system_description_table_header
-  {
-    std::array<char, 4> signature;
-    std::uint32_t length;
-    std::uint8_t revision;
-    std::uint8_t checksum;
-    std::array<char, 6> oem_id;
-    std::array<char, 8> oem_table_id;
-    std::uint32_t oem_revision;
-    std::uint32_t creator_id;
-    std::uint32_t create_revision;
-  };
+  //! Validate and ACPI entity checksum.
+  //!
+  //! @param data The data to validate the checksum of.
+  //! @return true iff. the checksum is valid, false otherwise.
+  auto validate_checksum(std::span<std::byte const> data) -> bool;
+
+  //! @}
 
 }  // namespace kapi::acpi
 
diff --git a/kapi/include/kapi/memory/layout.hpp b/kapi/include/kapi/memory/layout.hpp
index 157f41e..26b48d8 100644
--- a/kapi/include/kapi/memory/layout.hpp
+++ b/kapi/include/kapi/memory/layout.hpp
@@ -37,6 +37,18 @@ namespace kapi::memory
   //! The linear base address of the loaded kernel image.
   constexpr auto kernel_base = linear_address{0xffff'ffff'8000'0000uz};
 
+  //! Convert a physical address to a linear address using the higher-half direct map.
+  constexpr auto hhdm_to_linear(physical_address address) -> linear_address
+  {
+    return linear_address{address.raw() + higher_half_direct_map_base.raw()};
+  }
+
+  //! Convert a linear address in the higher-half direct map to a physical address.
+  constexpr auto hhdm_to_physical(linear_address address) -> physical_address
+  {
+    return physical_address{address.raw() - higher_half_direct_map_base.raw()};
+  }
+
 }  // namespace kapi::memory
 
 #endif
\ No newline at end of file
diff --git a/kernel/CMakeLists.txt b/kernel/CMakeLists.txt
index ab77467..fc01723 100644
--- a/kernel/CMakeLists.txt
+++ b/kernel/CMakeLists.txt
@@ -14,6 +14,7 @@ add_library("kernel_objs" OBJECT
     "kstd/print.cpp"
 
     # Kernel Implementation
+    "src/acpi/manager.cpp"
     "src/memory/bitmap_allocator.cpp"
     "src/memory/block_list_allocator.cpp"
     "src/memory.cpp"
diff --git a/kernel/include/kernel/acpi/manager.hpp b/kernel/include/kernel/acpi/manager.hpp
new file mode 100644
index 0000000..fc76685
--- /dev/null
+++ b/kernel/include/kernel/acpi/manager.hpp
@@ -0,0 +1,26 @@
+#ifndef TEACHOS_KERNEL_ACPI_MANAGER_HPP
+#define TEACHOS_KERNEL_ACPI_MANAGER_HPP
+
+#include "kapi/acpi.hpp"
+
+#include <kstd/vector>
+
+namespace kernel::acpi
+{
+
+  struct manager
+  {
+    explicit manager(kapi::acpi::root_system_description_pointer const & sdp);
+
+    auto load_tables() -> bool;
+
+  private:
+    kapi::acpi::root_system_description_pointer const * m_sdp{};
+    kapi::acpi::system_description_table_header const * m_rsdt{};
+    kstd::vector<kapi::acpi::system_description_table_header> m_tables{};
+    bool m_extended{};
+  };
+
+}  // namespace kernel::acpi
+
+#endif
diff --git a/kernel/kapi/acpi.cpp b/kernel/kapi/acpi.cpp
index aa0066d..787bcff 100644
--- a/kernel/kapi/acpi.cpp
+++ b/kernel/kapi/acpi.cpp
@@ -1,13 +1,18 @@
 #include "kapi/acpi.hpp"
 
 #include "kapi/memory.hpp"
+#include "kapi/system.hpp"
+
+#include "kernel/acpi/manager.hpp"
 
 #include <kstd/units>
 
 #include <algorithm>
+#include <atomic>
 #include <bit>
 #include <cstddef>
 #include <cstdint>
+#include <optional>
 #include <span>
 #include <string_view>
 
@@ -16,12 +21,7 @@ namespace kapi::acpi
 
   namespace
   {
-    constexpr auto validate_checksum(std::span<std::byte const> data) -> bool
-    {
-      auto sum = std::ranges::fold_left(
-          data, std::uint8_t{}, [](std::uint8_t acc, auto byte) { return static_cast<std::uint8_t>(byte) + acc; });
-      return sum == 0;
-    }
+    auto constinit manager = std::optional<kernel::acpi::manager>{};
   }  // namespace
 
   auto root_system_description_pointer::oem_id() const noexcept -> std::string_view
@@ -65,4 +65,24 @@ namespace kapi::acpi
     return validate_checksum({reinterpret_cast<std::byte const *>(this), m_length});
   }
 
+  auto init(root_system_description_pointer const & sdp) -> bool
+  {
+    auto static constinit initialized = std::atomic_flag{};
+    if (initialized.test_and_set())
+    {
+      system::panic("[OS::ACPI] The ACPI manager has already been initialized!");
+    }
+
+    manager.emplace(sdp);
+    return manager->load_tables();
+  }
+
+  auto validate_checksum(std::span<std::byte const> data) -> bool
+  {
+    auto sum = std::ranges::fold_left(data, std::uint8_t{}, [](auto acc, auto byte) {
+      return static_cast<std::uint8_t>(acc + static_cast<std::uint8_t>(byte));
+    });
+    return sum == 0;
+  }
+
 };  // namespace kapi::acpi
diff --git a/kernel/src/acpi/manager.cpp b/kernel/src/acpi/manager.cpp
new file mode 100644
index 0000000..6a17920
--- /dev/null
+++ b/kernel/src/acpi/manager.cpp
@@ -0,0 +1,54 @@
+#include "kernel/acpi/manager.hpp"
+
+#include "kapi/acpi.hpp"
+#include "kapi/memory.hpp"
+#include "kapi/system.hpp"
+
+#include <cstddef>
+
+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}))
+    {
+      kapi::system::panic("[OS:ACPI] Invalid RSDT checksum!");
+    }
+
+    return false;
+  }
+
+}  // namespace kernel::acpi