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 */
21 static struct attribute *devices_attr[] = {
22 NULL,
23 };
24
25 static const struct attribute_group iommu_devices_attr_group = {
26 .name = "devices",
27 .attrs = devices_attr,
28 };
29
30 static const struct attribute_group *iommu_dev_groups[] = {
31 &iommu_devices_attr_group,
32 NULL,
33 };
34
iommu_release_device(struct device * dev)35 static void iommu_release_device(struct device *dev)
36 {
37 kfree(dev);
38 }
39
40 static struct class iommu_class = {
41 .name = "iommu",
42 .dev_release = iommu_release_device,
43 .dev_groups = iommu_dev_groups,
44 };
45
iommu_dev_init(void)46 static int __init iommu_dev_init(void)
47 {
48 return class_register(&iommu_class);
49 }
50 postcore_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 */
iommu_device_create(struct device * parent,void * drvdata,const struct attribute_group ** groups,const char * fmt,...)57 struct 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
88 error:
89 put_device(dev);
90 return ERR_PTR(ret);
91 }
92
iommu_device_destroy(struct device * dev)93 void 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 */
iommu_device_link(struct device * dev,struct device * link)107 int 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
iommu_device_unlink(struct device * dev,struct device * link)127 void 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