drivers/iommu/iommu-sysfs.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * IOMMU sysfs class support
   4  *
   5  * Copyright (C) 2014 Red Hat, Inc.  All rights reserved.
   6  *     Author: Alex Williamson <alex.williamson@redhat.com>
   7  */
   8
   9 #include <linux/device.h>
  10 #include <linux/iommu.h>
  11 #include <linux/init.h>
  12 #include <linux/slab.h>
  13
  14 /*
  15  * We provide a common class "devices" group which initially has no attributes.
  16  * As devices are added to the IOMMU, we'll add links to the group.
  17  */
  18 static struct attribute *devices_attr[] = {
  19         NULL,
  20 };
  21
  22 static const struct attribute_group devices_attr_group = {
  23         .name = "devices",
  24         .attrs = devices_attr,
  25 };
  26
  27 static const struct attribute_group *dev_groups[] = {
  28         &devices_attr_group,
  29         NULL,
  30 };
  31
  32 static void release_device(struct device *dev)
  33 {
  34         kfree(dev);
  35 }
  36
  37 static struct class iommu_class = {
  38         .name = "iommu",
  39         .dev_release = release_device,
  40         .dev_groups = dev_groups,
  41 };
  42
  43 static int __init iommu_dev_init(void)
  44 {
  45         return class_register(&iommu_class);
  46 }
  47 postcore_initcall(iommu_dev_init);
  48
  49 /*
  50  * Init the struct device for the IOMMU. IOMMU specific attributes can
  51  * be provided as an attribute group, allowing a unique namespace per
  52  * IOMMU type.
  53  */
  54 int iommu_device_sysfs_add(struct iommu_device *iommu,
  55                            struct device *parent,
  56                            const struct attribute_group **groups,
  57                            const char *fmt, ...)
  58 {
  59         va_list vargs;
  60         int ret;
  61
  62         iommu->dev = kzalloc(sizeof(*iommu->dev), GFP_KERNEL);
  63         if (!iommu->dev)
  64                 return -ENOMEM;
  65
  66         device_initialize(iommu->dev);
  67
  68         iommu->dev->class = &iommu_class;
  69         iommu->dev->parent = parent;
  70         iommu->dev->groups = groups;
  71
  72         va_start(vargs, fmt);
  73         ret = kobject_set_name_vargs(&iommu->dev->kobj, fmt, vargs);
  74         va_end(vargs);
  75         if (ret)
  76                 goto error;
  77
  78         ret = device_add(iommu->dev);
  79         if (ret)
  80                 goto error;
  81
  82         dev_set_drvdata(iommu->dev, iommu);
  83
  84         return 0;
  85
  86 error:
  87         put_device(iommu->dev);
  88         return ret;
  89 }
  90 EXPORT_SYMBOL_GPL(iommu_device_sysfs_add);
  91
  92 void iommu_device_sysfs_remove(struct iommu_device *iommu)
  93 {
  94         dev_set_drvdata(iommu->dev, NULL);
  95         device_unregister(iommu->dev);
  96         iommu->dev = NULL;
  97 }
  98 EXPORT_SYMBOL_GPL(iommu_device_sysfs_remove);
  99
 100 /*
 101  * IOMMU drivers can indicate a device is managed by a given IOMMU using
 102  * this interface.  A link to the device will be created in the "devices"
 103  * directory of the IOMMU device in sysfs and an "iommu" link will be
 104  * created under the linked device, pointing back at the IOMMU device.
 105  */
 106 int iommu_device_link(struct iommu_device *iommu, struct device *link)
 107 {
 108         int ret;
 109
 110         if (!iommu || IS_ERR(iommu))
 111                 return -ENODEV;
 112
 113         ret = sysfs_add_link_to_group(&iommu->dev->kobj, "devices",
 114                                       &link->kobj, dev_name(link));
 115         if (ret)
 116                 return ret;
 117
 118         ret = sysfs_create_link_nowarn(&link->kobj, &iommu->dev->kobj, "iommu");
 119         if (ret)
 120                 sysfs_remove_link_from_group(&iommu->dev->kobj, "devices",
 121                                              dev_name(link));
 122
 123         return ret;
 124 }
 125 EXPORT_SYMBOL_GPL(iommu_device_link);
 126
 127 void iommu_device_unlink(struct iommu_device *iommu, struct device *link)
 128 {
 129         if (!iommu || IS_ERR(iommu))
 130                 return;
 131
 132         sysfs_remove_link(&link->kobj, "iommu");
 133         sysfs_remove_link_from_group(&iommu->dev->kobj, "devices", dev_name(link));
 134 }
 135 EXPORT_SYMBOL_GPL(iommu_device_unlink);