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  * 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  */
  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
  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  */
 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
 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 }