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 void 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}
 96
 97static const struct wmi_device_id wmi_bmof_id_table[] = {
 98	{ .guid_string = WMI_BMOF_GUID },
 99	{ },
100};
101
102static struct wmi_driver wmi_bmof_driver = {
103	.driver = {
104		.name = "wmi-bmof",
105	},
106	.probe = wmi_bmof_probe,
107	.remove = wmi_bmof_remove,
108	.id_table = wmi_bmof_id_table,
109};
110
111module_wmi_driver(wmi_bmof_driver);
112
113MODULE_DEVICE_TABLE(wmi, wmi_bmof_id_table);
114MODULE_AUTHOR("Andrew Lutomirski <luto@kernel.org>");
115MODULE_DESCRIPTION("WMI embedded Binary MOF driver");
116MODULE_LICENSE("GPL");