wmi-helpers.c

 1// SPDX-License-Identifier: GPL-2.0-or-later
 2/*
 3 * Lenovo Legion WMI helpers driver.
 4 *
 5 * The Lenovo Legion WMI interface is broken up into multiple GUID interfaces
 6 * that require cross-references between GUID's for some functionality. The
 7 * "Custom Mode" interface is a legacy interface for managing and displaying
 8 * CPU & GPU power and hwmon settings and readings. The "Other Mode" interface
 9 * is a modern interface that replaces or extends the "Custom Mode" interface
10 * methods. The "Gamezone" interface adds advanced features such as fan
11 * profiles and overclocking. The "Lighting" interface adds control of various
12 * status lights related to different hardware components. Each of these
13 * drivers uses a common procedure to get data from the WMI interface,
14 * enumerated here.
15 *
16 * Copyright (C) 2025 Derek J. Clark <derekjohn.clark@gmail.com>
17 */
18
19#include <linux/acpi.h>
20#include <linux/cleanup.h>
21#include <linux/errno.h>
22#include <linux/export.h>
23#include <linux/module.h>
24#include <linux/wmi.h>
25
26#include "wmi-helpers.h"
27
28/**
29 * lwmi_dev_evaluate_int() - Helper function for calling WMI methods that
30 * return an integer.
31 * @wdev: Pointer to the WMI device to be called.
32 * @instance: Instance of the called method.
33 * @method_id: WMI Method ID for the method to be called.
34 * @buf: Buffer of all arguments for the given method_id.
35 * @size: Length of the buffer.
36 * @retval: Pointer for the return value to be assigned.
37 *
38 * Calls wmidev_evaluate_method for Lenovo WMI devices that return an ACPI
39 * integer. Validates the return value type and assigns the value to the
40 * retval pointer.
41 *
42 * Return: 0 on success, or an error code.
43 */
44int lwmi_dev_evaluate_int(struct wmi_device *wdev, u8 instance, u32 method_id,
45			  unsigned char *buf, size_t size, u32 *retval)
46{
47	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
48	union acpi_object *ret_obj __free(kfree) = NULL;
49	struct acpi_buffer input = { size, buf };
50	acpi_status status;
51
52	status = wmidev_evaluate_method(wdev, instance, method_id, &input,
53					&output);
54	if (ACPI_FAILURE(status))
55		return -EIO;
56
57	if (retval) {
58		ret_obj = output.pointer;
59		if (!ret_obj)
60			return -ENODATA;
61
62		if (ret_obj->type != ACPI_TYPE_INTEGER)
63			return -ENXIO;
64
65		*retval = (u32)ret_obj->integer.value;
66	}
67
68	return 0;
69};
70EXPORT_SYMBOL_NS_GPL(lwmi_dev_evaluate_int, "LENOVO_WMI_HELPERS");
71
72MODULE_AUTHOR("Derek J. Clark <derekjohn.clark@gmail.com>");
73MODULE_DESCRIPTION("Lenovo WMI Helpers Driver");
74MODULE_LICENSE("GPL");