drivers/iommu/iommu-sysfs.c

   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
  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
  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  * Init the struct device for the IOMMU. IOMMU specific attributes can
  54  * be provided as an attribute group, allowing a unique namespace per
  55  * IOMMU type.
  56  */
  57 int iommu_device_sysfs_add(struct iommu_device *iommu,
  58                            struct device *parent,
  59                            const struct attribute_group **groups,
  60                            const char *fmt, ...)
  61 {
  62         va_list vargs;
  63         int ret;
  64
  65         iommu->dev = kzalloc(sizeof(*iommu->dev), GFP_KERNEL);
  66         if (!iommu->dev)
  67                 return -ENOMEM;
  68
  69         device_initialize(iommu->dev);
  70
  71         iommu->dev->class = &iommu_class;
  72         iommu->dev->parent = parent;
  73         iommu->dev->groups = groups;
  74
  75         va_start(vargs, fmt);
  76         ret = kobject_set_name_vargs(&iommu->dev->kobj, fmt, vargs);
  77         va_end(vargs);
  78         if (ret)
  79                 goto error;
  80
  81         ret = device_add(iommu->dev);
  82         if (ret)
  83                 goto error;
  84
  85         dev_set_drvdata(iommu->dev, iommu);
  86
  87         return 0;
  88
  89 error:
  90         put_device(iommu->dev);
  91         return ret;
  92 }
  93
  94 void iommu_device_sysfs_remove(struct iommu_device *iommu)
  95 {
  96         dev_set_drvdata(iommu->dev, NULL);
  97         device_unregister(iommu->dev);
  98         iommu->dev = NULL;
  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
 126 void iommu_device_unlink(struct iommu_device *iommu, struct device *link)
 127 {
 128         if (!iommu || IS_ERR(iommu))
 129                 return;
 130
 131         sysfs_remove_link(&link->kobj, "iommu");
 132         sysfs_remove_link_from_group(&iommu->dev->kobj, "devices", dev_name(link));
 133 }