fix: add backlight modulation support for hybrid graphics laptops

kernel/src/ACPI/AcpiWmi.hpp

@@ -0,0 +1,44 @@
+/*
+    * AcpiWmi.hpp
+    * ACPI-WMI mapper (PNP0C14): find a WMI GUID's data block in _WDG and call
+    * its WMxx method
+    * Copyright (c) 2026 Daniel Hammer
+*/
+
+#pragma once
+#include <cstdint>
+#include <ACPI/AML/AmlNamespace.hpp>
+
+namespace Hal {
+    namespace AcpiWmi {
+
+        // _WDG flags (Microsoft "Windows Instrumentation: WMI and ACPI").
+        static constexpr uint8_t FlagExpensive = 0x1;
+        static constexpr uint8_t FlagMethod    = 0x2;
+        static constexpr uint8_t FlagString    = 0x4;
+        static constexpr uint8_t FlagEvent     = 0x8;
+
+        // One _WDG entry, bound to the PNP0C14 device that declared it.
+        struct Block {
+            int32_t Device;          // namespace node of the PNP0C14 device
+            char    ObjectId[2];     // names the WQxx / WSxx / WMxx methods
+            uint8_t InstanceCount;
+            uint8_t Flags;
+        };
+
+        // Parse "603E9613-EF25-4338-A3D0-C46177516DB7" into the byte order
+        // _WDG stores (first three fields little-endian). False if malformed.
+        bool ParseGuid(const char* text, uint8_t out[16]);
+
+        // Search every present PNP0C14 device's _WDG for `guid`. The first
+        // declaration wins, as on Linux.
+        bool Find(const uint8_t guid[16], Block& out);
+
+        // Evaluate WMxx(instance, methodId, input) on a method block. The input
+        // is passed as a String instead of a Buffer when the block says so.
+        bool EvaluateMethod(const Block& block, uint8_t instance, uint32_t methodId,
+                            const uint8_t* input, uint32_t inputLength,
+                            AML::Object& result);
+
+    };
+};