/*
 * Copyright (C) 2007-2008 Advanced Micro Devices, Inc.
 * Author: Joerg Roedel <jroedel@suse.de>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */

#define pr_fmt(fmt)    "iommu: " fmt

#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/bug.h>
#include <linux/types.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/iommu.h>
#include <linux/idr.h>
#include <linux/notifier.h>
#include <linux/err.h>
#include <linux/pci.h>
#include <linux/bitops.h>
#include <linux/property.h>
#include <trace/events/iommu.h>

static struct kset *iommu_group_kset;
static DEFINE_IDA(iommu_group_ida);

struct iommu_callback_data {
        const struct iommu_ops *ops;
};

struct iommu_group {
        struct kobject kobj;
        struct kobject *devices_kobj;
        struct list_head devices;
        struct mutex mutex;
        struct blocking_notifier_head notifier;
        void *iommu_data;
        void (*iommu_data_release)(void *iommu_data);
        char *name;
        int id;
        struct iommu_domain *default_domain;
        struct iommu_domain *domain;
};

struct iommu_device {
        struct list_head list;
        struct device *dev;
        char *name;
};

struct iommu_group_attribute {
        struct attribute attr;
        ssize_t (*show)(struct iommu_group *group, char *buf);
        ssize_t (*store)(struct iommu_group *group,
                         const char *buf, size_t count);
};

#define IOMMU_GROUP_ATTR(_name, _mode, _show, _store)           \
struct iommu_group_attribute iommu_group_attr_##_name =         \
        __ATTR(_name, _mode, _show, _store)

#define to_iommu_group_attr(_attr)      \
        container_of(_attr, struct iommu_group_attribute, attr)
#define to_iommu_group(_kobj)           \
        container_of(_kobj, struct iommu_group, kobj)

static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus,
                                                 unsigned type);
static int __iommu_attach_device(struct iommu_domain *domain,
                                 struct device *dev);
static int __iommu_attach_group(struct iommu_domain *domain,
                                struct iommu_group *group);
static void __iommu_detach_group(struct iommu_domain *domain,
                                 struct iommu_group *group);

static ssize_t iommu_group_attr_show(struct kobject *kobj,
                                     struct attribute *__attr, char *buf)
{
        struct iommu_group_attribute *attr = to_iommu_group_attr(__attr);
        struct iommu_group *group = to_iommu_group(kobj);
        ssize_t ret = -EIO;

        if (attr->show)
                ret = attr->show(group, buf);
        return ret;
}

static ssize_t iommu_group_attr_store(struct kobject *kobj,
                                      struct attribute *__attr,
                                      const char *buf, size_t count)
{
        struct iommu_group_attribute *attr = to_iommu_group_attr(__attr);
        struct iommu_group *group = to_iommu_group(kobj);
        ssize_t ret = -EIO;

        if (attr->store)
                ret = attr->store(group, buf, count);
        return ret;
}

static const struct sysfs_ops iommu_group_sysfs_ops = {
        .show = iommu_group_attr_show,
        .store = iommu_group_attr_store,
};

static int iommu_group_create_file(struct iommu_group *group,
                                   struct iommu_group_attribute *attr)
{
        return sysfs_create_file(&group->kobj, &attr->attr);
}

static void iommu_group_remove_file(struct iommu_group *group,
                                    struct iommu_group_attribute *attr)
{
        sysfs_remove_file(&group->kobj, &attr->attr);
}

static ssize_t iommu_group_show_name(struct iommu_group *group, char *buf)
{
        return sprintf(buf, "%s\n", group->name);
}

static IOMMU_GROUP_ATTR(name, S_IRUGO, iommu_group_show_name, NULL);

static void iommu_group_release(struct kobject *kobj)
{
        struct iommu_group *group = to_iommu_group(kobj);

        pr_debug("Releasing group %d\n", group->id);

        if (group->iommu_data_release)
                group->iommu_data_release(group->iommu_data);

        ida_simple_remove(&iommu_group_ida, group->id);

        if (group->default_domain)
                iommu_domain_free(group->default_domain);

        kfree(group->name);
        kfree(group);
}

static struct kobj_type iommu_group_ktype = {
        .sysfs_ops = &iommu_group_sysfs_ops,
        .release = iommu_group_release,
};

/**
 * iommu_group_alloc - Allocate a new group
 * @name: Optional name to associate with group, visible in sysfs
 *
 * This function is called by an iommu driver to allocate a new iommu
 * group.  The iommu group represents the minimum granularity of the iommu.
 * Upon successful return, the caller holds a reference to the supplied
 * group in order to hold the group until devices are added.  Use
 * iommu_group_put() to release this extra reference count, allowing the
 * group to be automatically reclaimed once it has no devices or external
 * references.
 */
struct iommu_group *iommu_group_alloc(void)
{
        struct iommu_group *group;
        int ret;

        group = kzalloc(sizeof(*group), GFP_KERNEL);
        if (!group)
                return ERR_PTR(-ENOMEM);

        group->kobj.kset = iommu_group_kset;
        mutex_init(&group->mutex);
        INIT_LIST_HEAD(&group->devices);
        BLOCKING_INIT_NOTIFIER_HEAD(&group->notifier);

        ret = ida_simple_get(&iommu_group_ida, 0, 0, GFP_KERNEL);
        if (ret < 0) {
                kfree(group);
                return ERR_PTR(ret);
        }
        group->id = ret;

        ret = kobject_init_and_add(&group->kobj, &iommu_group_ktype,
                                   NULL, "%d", group->id);
        if (ret) {
                ida_simple_remove(&iommu_group_ida, group->id);
                kfree(group);
                return ERR_PTR(ret);
        }

        group->devices_kobj = kobject_create_and_add("devices", &group->kobj);
        if (!group->devices_kobj) {
                kobject_put(&group->kobj); /* triggers .release & free */
                return ERR_PTR(-ENOMEM);
        }

        /*
         * The devices_kobj holds a reference on the group kobject, so
         * as long as that exists so will the group.  We can therefore
         * use the devices_kobj for reference counting.
         */
        kobject_put(&group->kobj);

        pr_debug("Allocated group %d\n", group->id);

        return group;
}
EXPORT_SYMBOL_GPL(iommu_group_alloc);

struct iommu_group *iommu_group_get_by_id(int id)
{
        struct kobject *group_kobj;
        struct iommu_group *group;
        const char *name;

        if (!iommu_group_kset)
                return NULL;

        name = kasprintf(GFP_KERNEL, "%d", id);
        if (!name)
                return NULL;

        group_kobj = kset_find_obj(iommu_group_kset, name);
        kfree(name);

        if (!group_kobj)
                return NULL;

        group = container_of(group_kobj, struct iommu_group, kobj);
        BUG_ON(group->id != id);

        kobject_get(group->devices_kobj);
        kobject_put(&group->kobj);

        return group;
}
EXPORT_SYMBOL_GPL(iommu_group_get_by_id);

/**
 * iommu_group_get_iommudata - retrieve iommu_data registered for a group
 * @group: the group
 *
 * iommu drivers can store data in the group for use when doing iommu
 * operations.  This function provides a way to retrieve it.  Caller
 * should hold a group reference.
 */
void *iommu_group_get_iommudata(struct iommu_group *group)
{
        return group->iommu_data;
}
EXPORT_SYMBOL_GPL(iommu_group_get_iommudata);

/**
 * iommu_group_set_iommudata - set iommu_data for a group
 * @group: the group
 * @iommu_data: new data
 * @release: release function for iommu_data
 *
 * iommu drivers can store data in the group for use when doing iommu
 * operations.  This function provides a way to set the data after
 * the group has been allocated.  Caller should hold a group reference.
 */
void iommu_group_set_iommudata(struct iommu_group *group, void *iommu_data,
                               void (*release)(void *iommu_data))
{
        group->iommu_data = iommu_data;
        group->iommu_data_release = release;
}
EXPORT_SYMBOL_GPL(iommu_group_set_iommudata);

/**
 * iommu_group_set_name - set name for a group
 * @group: the group
 * @name: name
 *
 * Allow iommu driver to set a name for a group.  When set it will
 * appear in a name attribute file under the group in sysfs.
 */
int iommu_group_set_name(struct iommu_group *group, const char *name)
{
        int ret;

        if (group->name) {
                iommu_group_remove_file(group, &iommu_group_attr_name);
                kfree(group->name);
                group->name = NULL;
                if (!name)
                        return 0;
        }

        group->name = kstrdup(name, GFP_KERNEL);
        if (!group->name)
                return -ENOMEM;

        ret = iommu_group_create_file(group, &iommu_group_attr_name);
        if (ret) {
                kfree(group->name);
                group->name = NULL;
                return ret;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(iommu_group_set_name);

static int iommu_group_create_direct_mappings(struct iommu_group *group,
                                              struct device *dev)
{
        struct iommu_domain *domain = group->default_domain;
        struct iommu_dm_region *entry;
        struct list_head mappings;
        unsigned long pg_size;
        int ret = 0;

        if (!domain || domain->type != IOMMU_DOMAIN_DMA)
                return 0;

        BUG_ON(!domain->pgsize_bitmap);

        pg_size = 1UL << __ffs(domain->pgsize_bitmap);
        INIT_LIST_HEAD(&mappings);

        iommu_get_dm_regions(dev, &mappings);

        /* We need to consider overlapping regions for different devices */
        list_for_each_entry(entry, &mappings, list) {
                dma_addr_t start, end, addr;

                if (domain->ops->apply_dm_region)
                        domain->ops->apply_dm_region(dev, domain, entry);

                start = ALIGN(entry->start, pg_size);
                end   = ALIGN(entry->start + entry->length, pg_size);

                for (addr = start; addr < end; addr += pg_size) {
                        phys_addr_t phys_addr;

                        phys_addr = iommu_iova_to_phys(domain, addr);
                        if (phys_addr)
                                continue;

                        ret = iommu_map(domain, addr, addr, pg_size, entry->prot);
                        if (ret)
                                goto out;
                }

        }

out:
        iommu_put_dm_regions(dev, &mappings);

        return ret;
}

/**
 * iommu_group_add_device - add a device to an iommu group
 * @group: the group into which to add the device (reference should be held)
 * @dev: the device
 *
 * This function is called by an iommu driver to add a device into a
 * group.  Adding a device increments the group reference count.
 */
int iommu_group_add_device(struct iommu_group *group, struct device *dev)
{
        int ret, i = 0;
        struct iommu_device *device;

        device = kzalloc(sizeof(*device), GFP_KERNEL);
        if (!device)
                return -ENOMEM;

        device->dev = dev;

        ret = sysfs_create_link(&dev->kobj, &group->kobj, "iommu_group");
        if (ret) {
                kfree(device);
                return ret;
        }

        device->name = kasprintf(GFP_KERNEL, "%s", kobject_name(&dev->kobj));
rename:
        if (!device->name) {
                sysfs_remove_link(&dev->kobj, "iommu_group");
                kfree(device);
                return -ENOMEM;
        }

        ret = sysfs_create_link_nowarn(group->devices_kobj,
                                       &dev->kobj, device->name);
        if (ret) {
                kfree(device->name);
                if (ret == -EEXIST && i >= 0) {
                        /*
                         * Account for the slim chance of collision
                         * and append an instance to the name.
                         */
                        device->name = kasprintf(GFP_KERNEL, "%s.%d",
                                                 kobject_name(&dev->kobj), i++);
                        goto rename;
                }

                sysfs_remove_link(&dev->kobj, "iommu_group");
                kfree(device);
                return ret;
        }

        kobject_get(group->devices_kobj);

        dev->iommu_group = group;

        iommu_group_create_direct_mappings(group, dev);

        mutex_lock(&group->mutex);
        list_add_tail(&device->list, &group->devices);
        if (group->domain)
                __iommu_attach_device(group->domain, dev);
        mutex_unlock(&group->mutex);

        /* Notify any listeners about change to group. */
        blocking_notifier_call_chain(&group->notifier,
                                     IOMMU_GROUP_NOTIFY_ADD_DEVICE, dev);

        trace_add_device_to_group(group->id, dev);

        pr_info("Adding device %s to group %d\n", dev_name(dev), group->id);

        return 0;
}
EXPORT_SYMBOL_GPL(iommu_group_add_device);

/**
 * iommu_group_remove_device - remove a device from it's current group
 * @dev: device to be removed
 *
 * This function is called by an iommu driver to remove the device from
 * it's current group.  This decrements the iommu group reference count.
 */
void iommu_group_remove_device(struct device *dev)
{
        struct iommu_group *group = dev->iommu_group;
        struct iommu_device *tmp_device, *device = NULL;

        pr_info("Removing device %s from group %d\n", dev_name(dev), group->id);

        /* Pre-notify listeners that a device is being removed. */
        blocking_notifier_call_chain(&group->notifier,
                                     IOMMU_GROUP_NOTIFY_DEL_DEVICE, dev);

        mutex_lock(&group->mutex);
        list_for_each_entry(tmp_device, &group->devices, list) {
                if (tmp_device->dev == dev) {
                        device = tmp_device;
                        list_del(&device->list);
                        break;
                }
        }
        mutex_unlock(&group->mutex);

        if (!device)
                return;

        sysfs_remove_link(group->devices_kobj, device->name);
        sysfs_remove_link(&dev->kobj, "iommu_group");

        trace_remove_device_from_group(group->id, dev);

        kfree(device->name);
        kfree(device);
        dev->iommu_group = NULL;
        kobject_put(group->devices_kobj);
}
EXPORT_SYMBOL_GPL(iommu_group_remove_device);

static int iommu_group_device_count(struct iommu_group *group)
{
        struct iommu_device *entry;
        int ret = 0;

        list_for_each_entry(entry, &group->devices, list)
                ret++;

        return ret;
}

/**
 * iommu_group_for_each_dev - iterate over each device in the group
 * @group: the group
 * @data: caller opaque data to be passed to callback function
 * @fn: caller supplied callback function
 *
 * This function is called by group users to iterate over group devices.
 * Callers should hold a reference count to the group during callback.
 * The group->mutex is held across callbacks, which will block calls to
 * iommu_group_add/remove_device.
 */
static int __iommu_group_for_each_dev(struct iommu_group *group, void *data,
                                      int (*fn)(struct device *, void *))
{
        struct iommu_device *device;
        int ret = 0;

        list_for_each_entry(device, &group->devices, list) {
                ret = fn(device->dev, data);
                if (ret)
                        break;
        }
        return ret;
}


int iommu_group_for_each_dev(struct iommu_group *group, void *data,
                             int (*fn)(struct device *, void *))
{
        int ret;

        mutex_lock(&group->mutex);
        ret = __iommu_group_for_each_dev(group, data, fn);
        mutex_unlock(&group->mutex);

        return ret;
}
EXPORT_SYMBOL_GPL(iommu_group_for_each_dev);

/**
 * iommu_group_get - Return the group for a device and increment reference
 * @dev: get the group that this device belongs to
 *
 * This function is called by iommu drivers and users to get the group
 * for the specified device.  If found, the group is returned and the group
 * reference in incremented, else NULL.
 */
struct iommu_group *iommu_group_get(struct device *dev)
{
        struct iommu_group *group = dev->iommu_group;

        if (group)
                kobject_get(group->devices_kobj);

        return group;
}
EXPORT_SYMBOL_GPL(iommu_group_get);

/**
 * iommu_group_put - Decrement group reference
 * @group: the group to use
 *
 * This function is called by iommu drivers and users to release the
 * iommu group.  Once the reference count is zero, the group is released.
 */
void iommu_group_put(struct iommu_group *group)
{
        if (group)
                kobject_put(group->devices_kobj);
}
EXPORT_SYMBOL_GPL(iommu_group_put);

/**
 * iommu_group_register_notifier - Register a notifier for group changes
 * @group: the group to watch
 * @nb: notifier block to signal
 *
 * This function allows iommu group users to track changes in a group.
 * See include/linux/iommu.h for actions sent via this notifier.  Caller
 * should hold a reference to the group throughout notifier registration.
 */
int iommu_group_register_notifier(struct iommu_group *group,
                                  struct notifier_block *nb)
{
        return blocking_notifier_chain_register(&group->notifier, nb);
}
EXPORT_SYMBOL_GPL(iommu_group_register_notifier);

/**
 * iommu_group_unregister_notifier - Unregister a notifier
 * @group: the group to watch
 * @nb: notifier block to signal
 *
 * Unregister a previously registered group notifier block.
 */
int iommu_group_unregister_notifier(struct iommu_group *group,
                                    struct notifier_block *nb)
{
        return blocking_notifier_chain_unregister(&group->notifier, nb);
}
EXPORT_SYMBOL_GPL(iommu_group_unregister_notifier);

/**
 * iommu_group_id - Return ID for a group
 * @group: the group to ID
 *
 * Return the unique ID for the group matching the sysfs group number.
 */
int iommu_group_id(struct iommu_group *group)
{
        return group->id;
}
EXPORT_SYMBOL_GPL(iommu_group_id);

static struct iommu_group *get_pci_alias_group(struct pci_dev *pdev,
                                               unsigned long *devfns);

/*
 * To consider a PCI device isolated, we require ACS to support Source
 * Validation, Request Redirection, Completer Redirection, and Upstream
 * Forwarding.  This effectively means that devices cannot spoof their
 * requester ID, requests and completions cannot be redirected, and all
 * transactions are forwarded upstream, even as it passes through a
 * bridge where the target device is downstream.
 */
#define REQ_ACS_FLAGS   (PCI_ACS_SV | PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_UF)

/*
 * For multifunction devices which are not isolated from each other, find
 * all the other non-isolated functions and look for existing groups.  For
 * each function, we also need to look for aliases to or from other devices
 * that may already have a group.
 */
static struct iommu_group *get_pci_function_alias_group(struct pci_dev *pdev,
                                                        unsigned long *devfns)
{
        struct pci_dev *tmp = NULL;
        struct iommu_group *group;

        if (!pdev->multifunction || pci_acs_enabled(pdev, REQ_ACS_FLAGS))
                return NULL;

        for_each_pci_dev(tmp) {
                if (tmp == pdev || tmp->bus != pdev->bus ||
                    PCI_SLOT(tmp->devfn) != PCI_SLOT(pdev->devfn) ||
                    pci_acs_enabled(tmp, REQ_ACS_FLAGS))
                        continue;

                group = get_pci_alias_group(tmp, devfns);
                if (group) {
                        pci_dev_put(tmp);
                        return group;
                }
        }

        return NULL;
}

/*
 * Look for aliases to or from the given device for existing groups. DMA
 * aliases are only supported on the same bus, therefore the search
 * space is quite small (especially since we're really only looking at pcie
 * device, and therefore only expect multiple slots on the root complex or
 * downstream switch ports).  It's conceivable though that a pair of
 * multifunction devices could have aliases between them that would cause a
 * loop.  To prevent this, we use a bitmap to track where we've been.
 */
static struct iommu_group *get_pci_alias_group(struct pci_dev *pdev,
                                               unsigned long *devfns)
{
        struct pci_dev *tmp = NULL;
        struct iommu_group *group;

        if (test_and_set_bit(pdev->devfn & 0xff, devfns))
                return NULL;

        group = iommu_group_get(&pdev->dev);
        if (group)
                return group;

        for_each_pci_dev(tmp) {
                if (tmp == pdev || tmp->bus != pdev->bus)
                        continue;

                /* We alias them or they alias us */
                if (pci_devs_are_dma_aliases(pdev, tmp)) {
                        group = get_pci_alias_group(tmp, devfns);
                        if (group) {
                                pci_dev_put(tmp);
                                return group;
                        }

                        group = get_pci_function_alias_group(tmp, devfns);
                        if (group) {
                                pci_dev_put(tmp);
                                return group;
                        }
                }
        }

        return NULL;
}

struct group_for_pci_data {
        struct pci_dev *pdev;
        struct iommu_group *group;
};

/*
 * DMA alias iterator callback, return the last seen device.  Stop and return
 * the IOMMU group if we find one along the way.
 */
static int get_pci_alias_or_group(struct pci_dev *pdev, u16 alias, void *opaque)
{
        struct group_for_pci_data *data = opaque;

        data->pdev = pdev;
        data->group = iommu_group_get(&pdev->dev);

        return data->group != NULL;
}

/*
 * Generic device_group call-back function. It just allocates one
 * iommu-group per device.
 */
struct iommu_group *generic_device_group(struct device *dev)
{
        struct iommu_group *group;

        group = iommu_group_alloc();
        if (IS_ERR(group))
                return NULL;

        return group;
}

/*
 * Use standard PCI bus topology, isolation features, and DMA alias quirks
 * to find or create an IOMMU group for a device.
 */
struct iommu_group *pci_device_group(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        struct group_for_pci_data data;
        struct pci_bus *bus;
        struct iommu_group *group = NULL;
        u64 devfns[4] = { 0 };

        if (WARN_ON(!dev_is_pci(dev)))
                return ERR_PTR(-EINVAL);

        /*
         * Find the upstream DMA alias for the device.  A device must not
         * be aliased due to topology in order to have its own IOMMU group.
         * If we find an alias along the way that already belongs to a
         * group, use it.
         */
        if (pci_for_each_dma_alias(pdev, get_pci_alias_or_group, &data))
                return data.group;

        pdev = data.pdev;

        /*
         * Continue upstream from the point of minimum IOMMU granularity
         * due to aliases to the point where devices are protected from
         * peer-to-peer DMA by PCI ACS.  Again, if we find an existing
         * group, use it.
         */
        for (bus = pdev->bus; !pci_is_root_bus(bus); bus = bus->parent) {
                if (!bus->self)
                        continue;

                if (pci_acs_path_enabled(bus->self, NULL, REQ_ACS_FLAGS))
                        break;

                pdev = bus->self;

                group = iommu_group_get(&pdev->dev);
                if (group)
                        return group;
        }

        /*
         * Look for existing groups on device aliases.  If we alias another
         * device or another device aliases us, use the same group.
         */
        group = get_pci_alias_group(pdev, (unsigned long *)devfns);
        if (group)
                return group;

        /*
         * Look for existing groups on non-isolated functions on the same
         * slot and aliases of those funcions, if any.  No need to clear
         * the search bitmap, the tested devfns are still valid.
         */
        group = get_pci_function_alias_group(pdev, (unsigned long *)devfns);
        if (group)
                return group;

        /* No shared group found, allocate new */
        group = iommu_group_alloc();
        if (IS_ERR(group))
                return NULL;

        return group;
}

/**
 * iommu_group_get_for_dev - Find or create the IOMMU group for a device
 * @dev: target device
 *
 * This function is intended to be called by IOMMU drivers and extended to
 * support common, bus-defined algorithms when determining or creating the
 * IOMMU group for a device.  On success, the caller will hold a reference
 * to the returned IOMMU group, which will already include the provided
 * device.  The reference should be released with iommu_group_put().
 */
struct iommu_group *iommu_group_get_for_dev(struct device *dev)
{
        const struct iommu_ops *ops = dev->bus->iommu_ops;
        struct iommu_group *group;
        int ret;

        group = iommu_group_get(dev);
        if (group)
                return group;

        group = ERR_PTR(-EINVAL);

        if (ops && ops->device_group)
                group = ops->device_group(dev);

        if (IS_ERR(group))
                return group;

        /*
         * Try to allocate a default domain - needs support from the
         * IOMMU driver.
         */
        if (!group->default_domain) {
                group->default_domain = __iommu_domain_alloc(dev->bus,
                                                             IOMMU_DOMAIN_DMA);
                if (!group->domain)
                        group->domain = group->default_domain;
        }

        ret = iommu_group_add_device(group, dev);
        if (ret) {
                iommu_group_put(group);
                return ERR_PTR(ret);
        }

        return group;
}

struct iommu_domain *iommu_group_default_domain(struct iommu_group *group)
{
        return group->default_domain;
}

static int add_iommu_group(struct device *dev, void *data)
{
        struct iommu_callback_data *cb = data;
        const struct iommu_ops *ops = cb->ops;
        int ret;

        if (!ops->add_device)
                return 0;

        WARN_ON(dev->iommu_group);

        ret = ops->add_device(dev);

        /*
         * We ignore -ENODEV errors for now, as they just mean that the
         * device is not translated by an IOMMU. We still care about
         * other errors and fail to initialize when they happen.
         */
        if (ret == -ENODEV)
                ret = 0;

        return ret;
}

static int remove_iommu_group(struct device *dev, void *data)
{
        struct iommu_callback_data *cb = data;
        const struct iommu_ops *ops = cb->ops;

        if (ops->remove_device && dev->iommu_group)
                ops->remove_device(dev);

        return 0;
}

static int iommu_bus_notifier(struct notifier_block *nb,
                              unsigned long action, void *data)
{
        struct device *dev = data;
        const struct iommu_ops *ops = dev->bus->iommu_ops;
        struct iommu_group *group;
        unsigned long group_action = 0;

        /*
         * ADD/DEL call into iommu driver ops if provided, which may
         * result in ADD/DEL notifiers to group->notifier
         */
        if (action == BUS_NOTIFY_ADD_DEVICE) {
                if (ops->add_device)
                        return ops->add_device(dev);
        } else if (action == BUS_NOTIFY_REMOVED_DEVICE) {
                if (ops->remove_device && dev->iommu_group) {
                        ops->remove_device(dev);
                        return 0;
                }
        }

        /*
         * Remaining BUS_NOTIFYs get filtered and republished to the
         * group, if anyone is listening
         */
        group = iommu_group_get(dev);
        if (!group)
                return 0;

        switch (action) {
        case BUS_NOTIFY_BIND_DRIVER:
                group_action = IOMMU_GROUP_NOTIFY_BIND_DRIVER;
                break;
        case BUS_NOTIFY_BOUND_DRIVER:
                group_action = IOMMU_GROUP_NOTIFY_BOUND_DRIVER;
                break;
        case BUS_NOTIFY_UNBIND_DRIVER:
                group_action = IOMMU_GROUP_NOTIFY_UNBIND_DRIVER;
                break;
        case BUS_NOTIFY_UNBOUND_DRIVER:
                group_action = IOMMU_GROUP_NOTIFY_UNBOUND_DRIVER;
                break;
        }

        if (group_action)
                blocking_notifier_call_chain(&group->notifier,
                                             group_action, dev);

        iommu_group_put(group);
        return 0;
}

static int iommu_bus_init(struct bus_type *bus, const struct iommu_ops *ops)
{
        int err;
        struct notifier_block *nb;
        struct iommu_callback_data cb = {
                .ops = ops,
        };

        nb = kzalloc(sizeof(struct notifier_block), GFP_KERNEL);
        if (!nb)
                return -ENOMEM;

        nb->notifier_call = iommu_bus_notifier;

        err = bus_register_notifier(bus, nb);
        if (err)
                goto out_free;

        err = bus_for_each_dev(bus, NULL, &cb, add_iommu_group);
        if (err)
                goto out_err;


        return 0;

out_err:
        /* Clean up */
        bus_for_each_dev(bus, NULL, &cb, remove_iommu_group);
        bus_unregister_notifier(bus, nb);

out_free:
        kfree(nb);

        return err;
}

/**
 * bus_set_iommu - set iommu-callbacks for the bus
 * @bus: bus.
 * @ops: the callbacks provided by the iommu-driver
 *
 * This function is called by an iommu driver to set the iommu methods
 * used for a particular bus. Drivers for devices on that bus can use
 * the iommu-api after these ops are registered.
 * This special function is needed because IOMMUs are usually devices on
 * the bus itself, so the iommu drivers are not initialized when the bus
 * is set up. With this function the iommu-driver can set the iommu-ops
 * afterwards.
 */
int bus_set_iommu(struct bus_type *bus, const struct iommu_ops *ops)
{
        int err;

        if (bus->iommu_ops != NULL)
                return -EBUSY;

        bus->iommu_ops = ops;

        /* Do IOMMU specific setup for this bus-type */
        err = iommu_bus_init(bus, ops);
        if (err)
                bus->iommu_ops = NULL;

        return err;
}
EXPORT_SYMBOL_GPL(bus_set_iommu);

bool iommu_present(struct bus_type *bus)
{
        return bus->iommu_ops != NULL;
}
EXPORT_SYMBOL_GPL(iommu_present);

bool iommu_capable(struct bus_type *bus, enum iommu_cap cap)
{
        if (!bus->iommu_ops || !bus->iommu_ops->capable)
                return false;

        return bus->iommu_ops->capable(cap);
}
EXPORT_SYMBOL_GPL(iommu_capable);

/**
 * iommu_set_fault_handler() - set a fault handler for an iommu domain
 * @domain: iommu domain
 * @handler: fault handler
 * @token: user data, will be passed back to the fault handler
 *
 * This function should be used by IOMMU users which want to be notified
 * whenever an IOMMU fault happens.
 *
 * The fault handler itself should return 0 on success, and an appropriate
 * error code otherwise.
 */
void iommu_set_fault_handler(struct iommu_domain *domain,
                                        iommu_fault_handler_t handler,
                                        void *token)
{
        BUG_ON(!domain);

        domain->handler = handler;
        domain->handler_token = token;
}
EXPORT_SYMBOL_GPL(iommu_set_fault_handler);

static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus,
                                                 unsigned type)
{
        struct iommu_domain *domain;

        if (bus == NULL || bus->iommu_ops == NULL)
                return NULL;

        domain = bus->iommu_ops->domain_alloc(type);
        if (!domain)
                return NULL;

        domain->ops  = bus->iommu_ops;
        domain->type = type;
        /* Assume all sizes by default; the driver may override this later */
        domain->pgsize_bitmap  = bus->iommu_ops->pgsize_bitmap;

        return domain;
}

struct iommu_domain *iommu_domain_alloc(struct bus_type *bus)
{
        return __iommu_domain_alloc(bus, IOMMU_DOMAIN_UNMANAGED);
}
EXPORT_SYMBOL_GPL(iommu_domain_alloc);

void iommu_domain_free(struct iommu_domain *domain)
{
        domain->ops->domain_free(domain);
}
EXPORT_SYMBOL_GPL(iommu_domain_free);

static int __iommu_attach_device(struct iommu_domain *domain,
                                 struct device *dev)
{
        int ret;
        if (unlikely(domain->ops->attach_dev == NULL))
                return -ENODEV;

        ret = domain->ops->attach_dev(domain, dev);
        if (!ret)
                trace_attach_device_to_domain(dev);
        return ret;
}

int iommu_attach_device(struct iommu_domain *domain, struct device *dev)
{
        struct iommu_group *group;
        int ret;

        group = iommu_group_get(dev);
        /* FIXME: Remove this when groups a mandatory for iommu drivers */
        if (group == NULL)
                return __iommu_attach_device(domain, dev);

        /*
         * We have a group - lock it to make sure the device-count doesn't
         * change while we are attaching
         */
        mutex_lock(&group->mutex);
        ret = -EINVAL;
        if (iommu_group_device_count(group) != 1)
                goto out_unlock;

        ret = __iommu_attach_group(domain, group);

out_unlock:
        mutex_unlock(&group->mutex);
        iommu_group_put(group);

        return ret;
}
EXPORT_SYMBOL_GPL(iommu_attach_device);

static void __iommu_detach_device(struct iommu_domain *domain,
                                  struct device *dev)
{
        if (unlikely(domain->ops->detach_dev == NULL))
                return;

        domain->ops->detach_dev(domain, dev);
        trace_detach_device_from_domain(dev);
}

void iommu_detach_device(struct iommu_domain *domain, struct device *dev)
{
        struct iommu_group *group;

        group = iommu_group_get(dev);
        /* FIXME: Remove this when groups a mandatory for iommu drivers */
        if (group == NULL)
                return __iommu_detach_device(domain, dev);

        mutex_lock(&group->mutex);
        if (iommu_group_device_count(group) != 1) {
                WARN_ON(1);
                goto out_unlock;
        }

        __iommu_detach_group(domain, group);

out_unlock:
        mutex_unlock(&group->mutex);
        iommu_group_put(group);
}
EXPORT_SYMBOL_GPL(iommu_detach_device);

struct iommu_domain *iommu_get_domain_for_dev(struct device *dev)
{
        struct iommu_domain *domain;
        struct iommu_group *group;

        group = iommu_group_get(dev);
        /* FIXME: Remove this when groups a mandatory for iommu drivers */
        if (group == NULL)
                return NULL;

        domain = group->domain;

        iommu_group_put(group);

        return domain;
}
EXPORT_SYMBOL_GPL(iommu_get_domain_for_dev);

/*
 * IOMMU groups are really the natrual working unit of the IOMMU, but
 * the IOMMU API works on domains and devices.  Bridge that gap by
 * iterating over the devices in a group.  Ideally we'd have a single
 * device which represents the requestor ID of the group, but we also
 * allow IOMMU drivers to create policy defined minimum sets, where
 * the physical hardware may be able to distiguish members, but we
 * wish to group them at a higher level (ex. untrusted multi-function
 * PCI devices).  Thus we attach each device.
 */
static int iommu_group_do_attach_device(struct device *dev, void *data)
{
        struct iommu_domain *domain = data;

        return __iommu_attach_device(domain, dev);
}

static int __iommu_attach_group(struct iommu_domain *domain,
                                struct iommu_group *group)
{
        int ret;

        if (group->default_domain && group->domain != group->default_domain)
                return -EBUSY;

        ret = __iommu_group_for_each_dev(group, domain,
                                         iommu_group_do_attach_device);
        if (ret == 0)
                group->domain = domain;

        return ret;
}

int iommu_attach_group(struct iommu_domain *domain, struct iommu_group *group)
{
        int ret;

        mutex_lock(&group->mutex);
        ret = __iommu_attach_group(domain, group);
        mutex_unlock(&group->mutex);

        return ret;
}
EXPORT_SYMBOL_GPL(iommu_attach_group);

static int iommu_group_do_detach_device(struct device *dev, void *data)
{
        struct iommu_domain *domain = data;

        __iommu_detach_device(domain, dev);

        return 0;
}

static void __iommu_detach_group(struct iommu_domain *domain,
                                 struct iommu_group *group)
{
        int ret;

        if (!group->default_domain) {
                __iommu_group_for_each_dev(group, domain,
                                           iommu_group_do_detach_device);
                group->domain = NULL;
                return;
        }

        if (group->domain == group->default_domain)
                return;

        /* Detach by re-attaching to the default domain */
        ret = __iommu_group_for_each_dev(group, group->default_domain,
                                         iommu_group_do_attach_device);
        if (ret != 0)
                WARN_ON(1);
        else
                group->domain = group->default_domain;
}

void iommu_detach_group(struct iommu_domain *domain, struct iommu_group *group)
{
        mutex_lock(&group->mutex);
        __iommu_detach_group(domain, group);
        mutex_unlock(&group->mutex);
}
EXPORT_SYMBOL_GPL(iommu_detach_group);

phys_addr_t iommu_iova_to_phys(struct iommu_domain *domain, dma_addr_t iova)
{
        if (unlikely(domain->ops->iova_to_phys == NULL))
                return 0;

        return domain->ops->iova_to_phys(domain, iova);
}
EXPORT_SYMBOL_GPL(iommu_iova_to_phys);

static size_t iommu_pgsize(struct iommu_domain *domain,
                           unsigned long addr_merge, size_t size)
{
        unsigned int pgsize_idx;
        size_t pgsize;

        /* Max page size that still fits into 'size' */
        pgsize_idx = __fls(size);

        /* need to consider alignment requirements ? */
        if (likely(addr_merge)) {
                /* Max page size allowed by address */
                unsigned int align_pgsize_idx = __ffs(addr_merge);
                pgsize_idx = min(pgsize_idx, align_pgsize_idx);
        }

        /* build a mask of acceptable page sizes */
        pgsize = (1UL << (pgsize_idx + 1)) - 1;

        /* throw away page sizes not supported by the hardware */
        pgsize &= domain->pgsize_bitmap;

        /* make sure we're still sane */
        BUG_ON(!pgsize);

        /* pick the biggest page */
        pgsize_idx = __fls(pgsize);
        pgsize = 1UL << pgsize_idx;

        return pgsize;
}

int iommu_map(struct iommu_domain *domain, unsigned long iova,
              phys_addr_t paddr, size_t size, int prot)
{
        unsigned long orig_iova = iova;
        unsigned int min_pagesz;
        size_t orig_size = size;
        phys_addr_t orig_paddr = paddr;
        int ret = 0;

        if (unlikely(domain->ops->map == NULL ||
                     domain->pgsize_bitmap == 0UL))
                return -ENODEV;

        if (unlikely(!(domain->type & __IOMMU_DOMAIN_PAGING)))
                return -EINVAL;

        /* find out the minimum page size supported */
        min_pagesz = 1 << __ffs(domain->pgsize_bitmap);

        /*
         * both the virtual address and the physical one, as well as
         * the size of the mapping, must be aligned (at least) to the
         * size of the smallest page supported by the hardware
         */
        if (!IS_ALIGNED(iova | paddr | size, min_pagesz)) {
                pr_err("unaligned: iova 0x%lx pa %pa size 0x%zx min_pagesz 0x%x\n",
                       iova, &paddr, size, min_pagesz);
                return -EINVAL;
        }

        pr_debug("map: iova 0x%lx pa %pa size 0x%zx\n", iova, &paddr, size);

        while (size) {
                size_t pgsize = iommu_pgsize(domain, iova | paddr, size);

                pr_debug("mapping: iova 0x%lx pa %pa pgsize 0x%zx\n",
                         iova, &paddr, pgsize);

                ret = domain->ops->map(domain, iova, paddr, pgsize, prot);
                if (ret)
                        break;

                iova += pgsize;
                paddr += pgsize;
                size -= pgsize;
        }

        /* unroll mapping in case something went wrong */
        if (ret)
                iommu_unmap(domain, orig_iova, orig_size - size);
        else
                trace_map(orig_iova, orig_paddr, orig_size);

        return ret;
}
EXPORT_SYMBOL_GPL(iommu_map);

size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova, size_t size)
{
        size_t unmapped_page, unmapped = 0;
        unsigned int min_pagesz;
        unsigned long orig_iova = iova;

        if (unlikely(domain->ops->unmap == NULL ||
                     domain->pgsize_bitmap == 0UL))
                return -ENODEV;

        if (unlikely(!(domain->type & __IOMMU_DOMAIN_PAGING)))
                return -EINVAL;

        /* find out the minimum page size supported */
        min_pagesz = 1 << __ffs(domain->pgsize_bitmap);

        /*
         * The virtual address, as well as the size of the mapping, must be
         * aligned (at least) to the size of the smallest page supported
         * by the hardware
         */
        if (!IS_ALIGNED(iova | size, min_pagesz)) {
                pr_err("unaligned: iova 0x%lx size 0x%zx min_pagesz 0x%x\n",
                       iova, size, min_pagesz);
                return -EINVAL;
        }

        pr_debug("unmap this: iova 0x%lx size 0x%zx\n", iova, size);

        /*
         * Keep iterating until we either unmap 'size' bytes (or more)
         * or we hit an area that isn't mapped.
         */
        while (unmapped < size) {
                size_t pgsize = iommu_pgsize(domain, iova, size - unmapped);

                unmapped_page = domain->ops->unmap(domain, iova, pgsize);
                if (!unmapped_page)
                        break;

                pr_debug("unmapped: iova 0x%lx size 0x%zx\n",
                         iova, unmapped_page);

                iova += unmapped_page;
                unmapped += unmapped_page;
        }

        trace_unmap(orig_iova, size, unmapped);
        return unmapped;
}
EXPORT_SYMBOL_GPL(iommu_unmap);

size_t default_iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
                         struct scatterlist *sg, unsigned int nents, int prot)
{
        struct scatterlist *s;
        size_t mapped = 0;
        unsigned int i, min_pagesz;
        int ret;

        if (unlikely(domain->pgsize_bitmap == 0UL))
                return 0;

        min_pagesz = 1 << __ffs(domain->pgsize_bitmap);

        for_each_sg(sg, s, nents, i) {
                phys_addr_t phys = page_to_phys(sg_page(s)) + s->offset;

                /*
                 * We are mapping on IOMMU page boundaries, so offset within
                 * the page must be 0. However, the IOMMU may support pages
                 * smaller than PAGE_SIZE, so s->offset may still represent
                 * an offset of that boundary within the CPU page.
                 */
                if (!IS_ALIGNED(s->offset, min_pagesz))
                        goto out_err;

                ret = iommu_map(domain, iova + mapped, phys, s->length, prot);
                if (ret)
                        goto out_err;

                mapped += s->length;
        }

        return mapped;

out_err:
        /* undo mappings already done */
        iommu_unmap(domain, iova, mapped);

        return 0;

}
EXPORT_SYMBOL_GPL(default_iommu_map_sg);

int iommu_domain_window_enable(struct iommu_domain *domain, u32 wnd_nr,
                               phys_addr_t paddr, u64 size, int prot)
{
        if (unlikely(domain->ops->domain_window_enable == NULL))
                return -ENODEV;

        return domain->ops->domain_window_enable(domain, wnd_nr, paddr, size,
                                                 prot);
}
EXPORT_SYMBOL_GPL(iommu_domain_window_enable);

void iommu_domain_window_disable(struct iommu_domain *domain, u32 wnd_nr)
{
        if (unlikely(domain->ops->domain_window_disable == NULL))
                return;

        return domain->ops->domain_window_disable(domain, wnd_nr);
}
EXPORT_SYMBOL_GPL(iommu_domain_window_disable);

static int __init iommu_init(void)
{
        iommu_group_kset = kset_create_and_add("iommu_groups",
                                               NULL, kernel_kobj);
        BUG_ON(!iommu_group_kset);

        return 0;
}
core_initcall(iommu_init);

int iommu_domain_get_attr(struct iommu_domain *domain,
                          enum iommu_attr attr, void *data)
{
        struct iommu_domain_geometry *geometry;
        bool *paging;
        int ret = 0;
        u32 *count;

        switch (attr) {
        case DOMAIN_ATTR_GEOMETRY:
                geometry  = data;
                *geometry = domain->geometry;

                break;
        case DOMAIN_ATTR_PAGING:
                paging  = data;
                *paging = (domain->pgsize_bitmap != 0UL);
                break;
        case DOMAIN_ATTR_WINDOWS:
                count = data;

                if (domain->ops->domain_get_windows != NULL)
                        *count = domain->ops->domain_get_windows(domain);
                else
                        ret = -ENODEV;

                break;
        default:
                if (!domain->ops->domain_get_attr)
                        return -EINVAL;

                ret = domain->ops->domain_get_attr(domain, attr, data);
        }

        return ret;
}
EXPORT_SYMBOL_GPL(iommu_domain_get_attr);

int iommu_domain_set_attr(struct iommu_domain *domain,
                          enum iommu_attr attr, void *data)
{
        int ret = 0;
        u32 *count;

        switch (attr) {
        case DOMAIN_ATTR_WINDOWS:
                count = data;

                if (domain->ops->domain_set_windows != NULL)
                        ret = domain->ops->domain_set_windows(domain, *count);
                else
                        ret = -ENODEV;

                break;
        default:
                if (domain->ops->domain_set_attr == NULL)
                        return -EINVAL;

                ret = domain->ops->domain_set_attr(domain, attr, data);
        }

        return ret;
}
EXPORT_SYMBOL_GPL(iommu_domain_set_attr);

void iommu_get_dm_regions(struct device *dev, struct list_head *list)
{
        const struct iommu_ops *ops = dev->bus->iommu_ops;

        if (ops && ops->get_dm_regions)
                ops->get_dm_regions(dev, list);
}

void iommu_put_dm_regions(struct device *dev, struct list_head *list)
{
        const struct iommu_ops *ops = dev->bus->iommu_ops;

        if (ops && ops->put_dm_regions)
                ops->put_dm_regions(dev, list);
}

/* Request that a device is direct mapped by the IOMMU */
int iommu_request_dm_for_dev(struct device *dev)
{
        struct iommu_domain *dm_domain;
        struct iommu_group *group;
        int ret;

        /* Device must already be in a group before calling this function */
        group = iommu_group_get_for_dev(dev);
        if (IS_ERR(group))
                return PTR_ERR(group);

        mutex_lock(&group->mutex);

        /* Check if the default domain is already direct mapped */
        ret = 0;
        if (group->default_domain &&
            group->default_domain->type == IOMMU_DOMAIN_IDENTITY)
                goto out;

        /* Don't change mappings of existing devices */
        ret = -EBUSY;
        if (iommu_group_device_count(group) != 1)
                goto out;

        /* Allocate a direct mapped domain */
        ret = -ENOMEM;
        dm_domain = __iommu_domain_alloc(dev->bus, IOMMU_DOMAIN_IDENTITY);
        if (!dm_domain)
                goto out;

        /* Attach the device to the domain */
        ret = __iommu_attach_group(dm_domain, group);
        if (ret) {
                iommu_domain_free(dm_domain);
                goto out;
        }

        /* Make the direct mapped domain the default for this group */
        if (group->default_domain)
                iommu_domain_free(group->default_domain);
        group->default_domain = dm_domain;

        pr_info("Using direct mapping for device %s\n", dev_name(dev));

        ret = 0;
out:
        mutex_unlock(&group->mutex);
        iommu_group_put(group);

        return ret;
}

int iommu_fwspec_init(struct device *dev, struct fwnode_handle *iommu_fwnode,
                      const struct iommu_ops *ops)
{
        struct iommu_fwspec *fwspec = dev->iommu_fwspec;

        if (fwspec)
                return ops == fwspec->ops ? 0 : -EINVAL;

        fwspec = kzalloc(sizeof(*fwspec), GFP_KERNEL);
        if (!fwspec)
                return -ENOMEM;

        of_node_get(to_of_node(iommu_fwnode));
        fwspec->iommu_fwnode = iommu_fwnode;
        fwspec->ops = ops;
        dev->iommu_fwspec = fwspec;
        return 0;
}
EXPORT_SYMBOL_GPL(iommu_fwspec_init);

void iommu_fwspec_free(struct device *dev)
{
        struct iommu_fwspec *fwspec = dev->iommu_fwspec;

        if (fwspec) {
                fwnode_handle_put(fwspec->iommu_fwnode);
                kfree(fwspec);
                dev->iommu_fwspec = NULL;
        }
}
EXPORT_SYMBOL_GPL(iommu_fwspec_free);

int iommu_fwspec_add_ids(struct device *dev, u32 *ids, int num_ids)
{
        struct iommu_fwspec *fwspec = dev->iommu_fwspec;
        size_t size;
        int i;

        if (!fwspec)
                return -EINVAL;

        size = offsetof(struct iommu_fwspec, ids[fwspec->num_ids + num_ids]);
        if (size > sizeof(*fwspec)) {
                fwspec = krealloc(dev->iommu_fwspec, size, GFP_KERNEL);
                if (!fwspec)
                        return -ENOMEM;
        }

        for (i = 0; i < num_ids; i++)
                fwspec->ids[fwspec->num_ids + i] = ids[i];

        fwspec->num_ids += num_ids;
        dev->iommu_fwspec = fwspec;
        return 0;
}
EXPORT_SYMBOL_GPL(iommu_fwspec_add_ids);