uniwill-wmi.c

 1// SPDX-License-Identifier: GPL-2.0-or-later
 2/*
 3 * Linux hotkey driver for Uniwill notebooks.
 4 *
 5 * Special thanks go to Pőcze Barnabás, Christoffer Sandberg and Werner Sembach
 6 * for supporting the development of this driver either through prior work or
 7 * by answering questions regarding the underlying WMI interface.
 8 *
 9 * Copyright (C) 2025 Armin Wolf <W_Armin@gmx.de>
10 */
11
12#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13
14#include <linux/acpi.h>
15#include <linux/device.h>
16#include <linux/init.h>
17#include <linux/mod_devicetable.h>
18#include <linux/notifier.h>
19#include <linux/printk.h>
20#include <linux/types.h>
21#include <linux/wmi.h>
22
23#include "uniwill-wmi.h"
24
25#define DRIVER_NAME		"uniwill-wmi"
26#define UNIWILL_EVENT_GUID	"ABBC0F72-8EA1-11D1-00A0-C90629100000"
27
28static BLOCKING_NOTIFIER_HEAD(uniwill_wmi_chain_head);
29
30static void devm_uniwill_wmi_unregister_notifier(void *data)
31{
32	struct notifier_block *nb = data;
33
34	blocking_notifier_chain_unregister(&uniwill_wmi_chain_head, nb);
35}
36
37int devm_uniwill_wmi_register_notifier(struct device *dev, struct notifier_block *nb)
38{
39	int ret;
40
41	ret = blocking_notifier_chain_register(&uniwill_wmi_chain_head, nb);
42	if (ret < 0)
43		return ret;
44
45	return devm_add_action_or_reset(dev, devm_uniwill_wmi_unregister_notifier, nb);
46}
47
48static void uniwill_wmi_notify(struct wmi_device *wdev, union acpi_object *obj)
49{
50	u32 value;
51
52	if (obj->type != ACPI_TYPE_INTEGER)
53		return;
54
55	value = obj->integer.value;
56
57	dev_dbg(&wdev->dev, "Received WMI event %u\n", value);
58
59	blocking_notifier_call_chain(&uniwill_wmi_chain_head, value, NULL);
60}
61
62/*
63 * We cannot fully trust this GUID since Uniwill just copied the WMI GUID
64 * from the Windows driver example, and others probably did the same.
65 *
66 * Because of this we cannot use this WMI GUID for autoloading. Instead the
67 * associated driver will be registered manually after matching a DMI table.
68 */
69static const struct wmi_device_id uniwill_wmi_id_table[] = {
70	{ UNIWILL_EVENT_GUID, NULL },
71	{ }
72};
73
74static struct wmi_driver uniwill_wmi_driver = {
75	.driver = {
76		.name = DRIVER_NAME,
77		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
78	},
79	.id_table = uniwill_wmi_id_table,
80	.notify = uniwill_wmi_notify,
81	.no_singleton = true,
82};
83
84int __init uniwill_wmi_register_driver(void)
85{
86	return wmi_driver_register(&uniwill_wmi_driver);
87}
88
89void __exit uniwill_wmi_unregister_driver(void)
90{
91	wmi_driver_unregister(&uniwill_wmi_driver);
92}