platform/x86: Add lenovo-wmi-helpers

Adds lenovo-wmi-helpers, which provides a common wrapper function for
wmidev_evaluate_method that does data validation and error handling.

Reviewed-by: Alok Tiwari <alok.a.tiwari@oracle.com>
Reviewed-by: Armin Wolf <W_Armin@gmx.de>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Derek J. Clark <derekjohn.clark@gmail.com>
Link: https://lore.kernel.org/r/20250702033826.1057762-3-derekjohn.clark@gmail.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

drivers/platform/x86/lenovo/Kconfig

@@ -232,3 +232,7 @@ config YT2_1380
 
 	  To compile this driver as a module, choose M here: the module will
 	  be called lenovo-yogabook.
+
+config LENOVO_WMI_HELPERS
+	tristate
+	depends on ACPI_WMI

drivers/platform/x86/lenovo/Makefile

@@ -12,6 +12,7 @@ lenovo-target-$(CONFIG_LENOVO_YMC)	+= ymc.o
 lenovo-target-$(CONFIG_YOGABOOK)	+= yogabook.o
 lenovo-target-$(CONFIG_YT2_1380)	+= yoga-tab2-pro-1380-fastcharger.o
 lenovo-target-$(CONFIG_LENOVO_WMI_CAMERA)	+= wmi-camera.o
+lenovo-target-$(CONFIG_LENOVO_WMI_HELPERS)	+= wmi-helpers.o
 
 # Add 'lenovo' prefix to each module listed in lenovo-target-*
 define LENOVO_OBJ_TARGET

drivers/platform/x86/lenovo/wmi-helpers.c

@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Lenovo Legion WMI helpers driver.
+ *
+ * The Lenovo Legion WMI interface is broken up into multiple GUID interfaces
+ * that require cross-references between GUID's for some functionality. The
+ * "Custom Mode" interface is a legacy interface for managing and displaying
+ * CPU & GPU power and hwmon settings and readings. The "Other Mode" interface
+ * is a modern interface that replaces or extends the "Custom Mode" interface
+ * methods. The "Gamezone" interface adds advanced features such as fan
+ * profiles and overclocking. The "Lighting" interface adds control of various
+ * status lights related to different hardware components. Each of these
+ * drivers uses a common procedure to get data from the WMI interface,
+ * enumerated here.
+ *
+ * Copyright (C) 2025 Derek J. Clark <derekjohn.clark@gmail.com>
+ */
+
+#include <linux/acpi.h>
+#include <linux/cleanup.h>
+#include <linux/errno.h>
+#include <linux/export.h>
+#include <linux/module.h>
+#include <linux/wmi.h>
+
+#include "wmi-helpers.h"
+
+/**
+ * lwmi_dev_evaluate_int() - Helper function for calling WMI methods that
+ * return an integer.
+ * @wdev: Pointer to the WMI device to be called.
+ * @instance: Instance of the called method.
+ * @method_id: WMI Method ID for the method to be called.
+ * @buf: Buffer of all arguments for the given method_id.
+ * @size: Length of the buffer.
+ * @retval: Pointer for the return value to be assigned.
+ *
+ * Calls wmidev_evaluate_method for Lenovo WMI devices that return an ACPI
+ * integer. Validates the return value type and assigns the value to the
+ * retval pointer.
+ *
+ * Return: 0 on success, or an error code.
+ */
+int lwmi_dev_evaluate_int(struct wmi_device *wdev, u8 instance, u32 method_id,
+			  unsigned char *buf, size_t size, u32 *retval)
+{
+	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
+	union acpi_object *ret_obj __free(kfree) = NULL;
+	struct acpi_buffer input = { size, buf };
+	acpi_status status;
+
+	status = wmidev_evaluate_method(wdev, instance, method_id, &input,
+					&output);
+	if (ACPI_FAILURE(status))
+		return -EIO;
+
+	if (retval) {
+		ret_obj = output.pointer;
+		if (!ret_obj)
+			return -ENODATA;
+
+		if (ret_obj->type != ACPI_TYPE_INTEGER)
+			return -ENXIO;
+
+		*retval = (u32)ret_obj->integer.value;
+	}
+
+	return 0;
+};
+EXPORT_SYMBOL_NS_GPL(lwmi_dev_evaluate_int, "LENOVO_WMI_HELPERS");
+
+MODULE_AUTHOR("Derek J. Clark <derekjohn.clark@gmail.com>");
+MODULE_DESCRIPTION("Lenovo WMI Helpers Driver");
+MODULE_LICENSE("GPL");

drivers/platform/x86/lenovo/wmi-helpers.h

@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+/* Copyright (C) 2025 Derek J. Clark <derekjohn.clark@gmail.com> */
+
+#ifndef _LENOVO_WMI_HELPERS_H_
+#define _LENOVO_WMI_HELPERS_H_
+
+#include <linux/types.h>
+
+struct wmi_device;
+
+struct wmi_method_args_32 {
+	u32 arg0;
+	u32 arg1;
+};
+
+int lwmi_dev_evaluate_int(struct wmi_device *wdev, u8 instance, u32 method_id,
+			  unsigned char *buf, size_t size, u32 *retval);
+
+#endif /* !_LENOVO_WMI_HELPERS_H_ */