feat: Ahci, ACPI shutdown

kernel/src/ACPI/AcpiShutdown.hpp

@@ -0,0 +1,24 @@
+/*
+    * AcpiShutdown.hpp
+    * ACPI S5 (soft-off) shutdown via PM1 control registers
+    * Copyright (c) 2026 Daniel Hammer
+*/
+
+#pragma once
+#include <ACPI/ACPI.hpp>
+
+namespace Hal {
+    namespace AcpiShutdown {
+
+        // Parse the FADT and DSDT from the XSDT to prepare shutdown values.
+        // Must be called during boot before any shutdown attempt.
+        void Initialize(ACPI::CommonSDTHeader* xsdt);
+
+        // Returns true if ACPI shutdown is available (Initialize succeeded).
+        bool IsAvailable();
+
+        // Perform an ACPI S5 shutdown by writing to PM1a/PM1b control registers.
+        // Does not return on success.
+        void Shutdown();
+    };
+};