iommu-sysfs.c revision ffd78f0093ecd0840ad6436e0522a53defd5df38 
1/*
2 * IOMMU sysfs class support
3 *
4 * Copyright (C) 2014 Red Hat, Inc.  All rights reserved.
5 *     Author: Alex Williamson <alex.williamson@redhat.com>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11
12#include <linux/device.h>
13#include <linux/iommu.h>
14#include <linux/module.h>
15#include <linux/slab.h>
16
17/*
18 * We provide a common class "devices" group which initially has no attributes.
19 * As devices are added to the IOMMU, we'll add links to the group.
20 */
21static struct attribute *devices_attr[] = {
22	NULL,
23};
24
25static const struct attribute_group iommu_devices_attr_group = {
26	.name = "devices",
27	.attrs = devices_attr,
28};
29
30static const struct attribute_group *iommu_dev_groups[] = {
31	&iommu_devices_attr_group,
32	NULL,
33};
34
35static void iommu_release_device(struct device *dev)
36{
37	kfree(dev);
38}
39
40static struct class iommu_class = {
41	.name = "iommu",
42	.dev_release = iommu_release_device,
43	.dev_groups = iommu_dev_groups,
44};
45
46static int __init iommu_dev_init(void)
47{
48	return class_register(&iommu_class);
49}
50postcore_initcall(iommu_dev_init);
51
52/*
53 * Create an IOMMU device and return a pointer to it.  IOMMU specific
54 * attributes can be provided as an attribute group, allowing a unique
55 * namespace per IOMMU type.
56 */
57struct device *iommu_device_create(struct device *parent, void *drvdata,
58				   const struct attribute_group **groups,
59				   const char *fmt, ...)
60{
61	struct device *dev;
62	va_list vargs;
63	int ret;
64
65	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
66	if (!dev)
67		return ERR_PTR(-ENOMEM);
68
69	device_initialize(dev);
70
71	dev->class = &iommu_class;
72	dev->parent = parent;
73	dev->groups = groups;
74	dev_set_drvdata(dev, drvdata);
75
76	va_start(vargs, fmt);
77	ret = kobject_set_name_vargs(&dev->kobj, fmt, vargs);
78	va_end(vargs);
79	if (ret)
80		goto error;
81
82	ret = device_add(dev);
83	if (ret)
84		goto error;
85
86	return dev;
87
88error:
89	put_device(dev);
90	return ERR_PTR(ret);
91}
92
93void iommu_device_destroy(struct device *dev)
94{
95	if (!dev || IS_ERR(dev))
96		return;
97
98	device_unregister(dev);
99}
100
101/*
102 * IOMMU drivers can indicate a device is managed by a given IOMMU using
103 * this interface.  A link to the device will be created in the "devices"
104 * directory of the IOMMU device in sysfs and an "iommu" link will be
105 * created under the linked device, pointing back at the IOMMU device.
106 */
107int iommu_device_link(struct device *dev, struct device *link)
108{
109	int ret;
110
111	if (!dev || IS_ERR(dev))
112		return -ENODEV;
113
114	ret = sysfs_add_link_to_group(&dev->kobj, "devices",
115				      &link->kobj, dev_name(link));
116	if (ret)
117		return ret;
118
119	ret = sysfs_create_link_nowarn(&link->kobj, &dev->kobj, "iommu");
120	if (ret)
121		sysfs_remove_link_from_group(&dev->kobj, "devices",
122					     dev_name(link));
123
124	return ret;
125}
126
127void iommu_device_unlink(struct device *dev, struct device *link)
128{
129	if (!dev || IS_ERR(dev))
130		return;
131
132	sysfs_remove_link(&link->kobj, "iommu");
133	sysfs_remove_link_from_group(&dev->kobj, "devices", dev_name(link));
134}
135