1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * WMI embedded Binary MOF driver
4 *
5 * Copyright (c) 2015 Andrew Lutomirski
6 * Copyright (C) 2017 VMware, Inc. All Rights Reserved.
7 */
8
9#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10
11#include <linux/acpi.h>
12#include <linux/device.h>
13#include <linux/fs.h>
14#include <linux/kernel.h>
15#include <linux/module.h>
16#include <linux/string.h>
17#include <linux/sysfs.h>
18#include <linux/types.h>
19#include <linux/wmi.h>
20
21#define WMI_BMOF_GUID "05901221-D566-11D1-B2F0-00A0C9062910"
22
23struct bmof_priv {
24	union acpi_object *bmofdata;
25	struct bin_attribute bmof_bin_attr;
26};
27
28static ssize_t
29read_bmof(struct file *filp, struct kobject *kobj,
30	 struct bin_attribute *attr,
31	 char *buf, loff_t off, size_t count)
32{
33	struct bmof_priv *priv =
34		container_of(attr, struct bmof_priv, bmof_bin_attr);
35
36	if (off < 0)
37		return -EINVAL;
38
39	if (off >= priv->bmofdata->buffer.length)
40		return 0;
41
42	if (count > priv->bmofdata->buffer.length - off)
43		count = priv->bmofdata->buffer.length - off;
44
45	memcpy(buf, priv->bmofdata->buffer.pointer + off, count);
46	return count;
47}
48
49static int wmi_bmof_probe(struct wmi_device *wdev, const void *context)
50{
51	struct bmof_priv *priv;
52	int ret;
53
54	priv = devm_kzalloc(&wdev->dev, sizeof(struct bmof_priv), GFP_KERNEL);
55	if (!priv)
56		return -ENOMEM;
57
58	dev_set_drvdata(&wdev->dev, priv);
59
60	priv->bmofdata = wmidev_block_query(wdev, 0);
61	if (!priv->bmofdata) {
62		dev_err(&wdev->dev, "failed to read Binary MOF\n");
63		return -EIO;
64	}
65
66	if (priv->bmofdata->type != ACPI_TYPE_BUFFER) {
67		dev_err(&wdev->dev, "Binary MOF is not a buffer\n");
68		ret = -EIO;
69		goto err_free;
70	}
71
72	sysfs_bin_attr_init(&priv->bmof_bin_attr);
73	priv->bmof_bin_attr.attr.name = "bmof";
74	priv->bmof_bin_attr.attr.mode = 0400;
75	priv->bmof_bin_attr.read = read_bmof;
76	priv->bmof_bin_attr.size = priv->bmofdata->buffer.length;
77
78	ret = sysfs_create_bin_file(&wdev->dev.kobj, &priv->bmof_bin_attr);
79	if (ret)
80		goto err_free;
81
82	return 0;
83
84 err_free:
85	kfree(priv->bmofdata);
86	return ret;
87}
88
89static int wmi_bmof_remove(struct wmi_device *wdev)
90{
91	struct bmof_priv *priv = dev_get_drvdata(&wdev->dev);
92
93	sysfs_remove_bin_file(&wdev->dev.kobj, &priv->bmof_bin_attr);
94	kfree(priv->bmofdata);
95	return 0;
96}
97
98static const struct wmi_device_id wmi_bmof_id_table[] = {
99	{ .guid_string = WMI_BMOF_GUID },
100	{ },
101};
102
103static struct wmi_driver wmi_bmof_driver = {
104	.driver = {
105		.name = "wmi-bmof",
106	},
107	.probe = wmi_bmof_probe,
108	.remove = wmi_bmof_remove,
109	.id_table = wmi_bmof_id_table,
110};
111
112module_wmi_driver(wmi_bmof_driver);
113
114MODULE_DEVICE_TABLE(wmi, wmi_bmof_id_table);
115MODULE_AUTHOR("Andrew Lutomirski <luto@kernel.org>");
116MODULE_DESCRIPTION("WMI embedded Binary MOF driver");
117MODULE_LICENSE("GPL");
118