iommu: Remove group_mf

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / drivers / iommu / iommu.c

/*
 * Copyright (C) 2007-2008 Advanced Micro Devices, Inc.
 * Author: Joerg Roedel <joerg.roedel@amd.com>
 *
 * 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)    "%s: " fmt, __func__

#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>

static struct kset *iommu_group_kset;
static struct ida iommu_group_ida;
static struct mutex iommu_group_mutex;

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_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 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);

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

        mutex_lock(&iommu_group_mutex);
        ida_remove(&iommu_group_ida, group->id);
        mutex_unlock(&iommu_group_mutex);

        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);

        mutex_lock(&iommu_group_mutex);

again:
        if (unlikely(0 == ida_pre_get(&iommu_group_ida, GFP_KERNEL))) {
                kfree(group);
                mutex_unlock(&iommu_group_mutex);
                return ERR_PTR(-ENOMEM);
        }

        if (-EAGAIN == ida_get_new(&iommu_group_ida, &group->id))
                goto again;

        mutex_unlock(&iommu_group_mutex);

        ret = kobject_init_and_add(&group->kobj, &iommu_group_ktype,
                                   NULL, "%d", group->id);
        if (ret) {
                mutex_lock(&iommu_group_mutex);
                ida_remove(&iommu_group_ida, group->id);
                mutex_unlock(&iommu_group_mutex);
                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);

        return group;
}
EXPORT_SYMBOL_GPL(iommu_group_alloc);

/**
 * 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);

/**
 * 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;

        mutex_lock(&group->mutex);
        list_add_tail(&device->list, &group->devices);
        mutex_unlock(&group->mutex);

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

        /* 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");

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

/**
 * 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.
 */
int iommu_group_for_each_dev(struct iommu_group *group, void *data,
                             int (*fn)(struct device *, void *))
{
        struct iommu_device *device;
        int ret = 0;

        mutex_lock(&group->mutex);
        list_for_each_entry(device, &group->devices, list) {
                ret = fn(device->dev, data);
                if (ret)
                        break;
        }
        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 int add_iommu_group(struct device *dev, void *data)
{
        struct iommu_ops *ops = data;

        if (!ops->add_device)
                return -ENODEV;

        WARN_ON(dev->iommu_group);

        ops->add_device(dev);

        return 0;
}

static int iommu_bus_notifier(struct notifier_block *nb,
                              unsigned long action, void *data)
{
        struct device *dev = data;
        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_DEL_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 struct notifier_block iommu_bus_nb = {
        .notifier_call = iommu_bus_notifier,
};

static void iommu_bus_init(struct bus_type *bus, struct iommu_ops *ops)
{
        bus_register_notifier(bus, &iommu_bus_nb);
        bus_for_each_dev(bus, NULL, ops, add_iommu_group);
}

/**
 * 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, struct iommu_ops *ops)
{
        if (bus->iommu_ops != NULL)
                return -EBUSY;

        bus->iommu_ops = ops;

        /* Do IOMMU specific setup for this bus-type */
        iommu_bus_init(bus, ops);

        return 0;
}
EXPORT_SYMBOL_GPL(bus_set_iommu);

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

/**
 * 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);

struct iommu_domain *iommu_domain_alloc(struct bus_type *bus)
{
        struct iommu_domain *domain;
        int ret;

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

        domain = kzalloc(sizeof(*domain), GFP_KERNEL);
        if (!domain)
                return NULL;

        domain->ops = bus->iommu_ops;

        ret = domain->ops->domain_init(domain);
        if (ret)
                goto out_free;

        return domain;

out_free:
        kfree(domain);

        return NULL;
}
EXPORT_SYMBOL_GPL(iommu_domain_alloc);

void iommu_domain_free(struct iommu_domain *domain)
{
        if (likely(domain->ops->domain_destroy != NULL))
                domain->ops->domain_destroy(domain);

        kfree(domain);
}
EXPORT_SYMBOL_GPL(iommu_domain_free);

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

        return domain->ops->attach_dev(domain, dev);
}
EXPORT_SYMBOL_GPL(iommu_attach_device);

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);
}
EXPORT_SYMBOL_GPL(iommu_detach_device);

/*
 * 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);
}

int iommu_attach_group(struct iommu_domain *domain, struct iommu_group *group)
{
        return iommu_group_for_each_dev(group, domain,
                                        iommu_group_do_attach_device);
}
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;
}

void iommu_detach_group(struct iommu_domain *domain, struct iommu_group *group)
{
        iommu_group_for_each_dev(group, domain, iommu_group_do_detach_device);
}
EXPORT_SYMBOL_GPL(iommu_detach_group);

phys_addr_t iommu_iova_to_phys(struct iommu_domain *domain,
                               unsigned long 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);

int iommu_domain_has_cap(struct iommu_domain *domain,
                         unsigned long cap)
{
        if (unlikely(domain->ops->domain_has_cap == NULL))
                return 0;

        return domain->ops->domain_has_cap(domain, cap);
}
EXPORT_SYMBOL_GPL(iommu_domain_has_cap);

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;
        int ret = 0;

        if (unlikely(domain->ops->map == NULL))
                return -ENODEV;

        /* find out the minimum page size supported */
        min_pagesz = 1 << __ffs(domain->ops->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 0x%lx size 0x%lx min_pagesz "
                        "0x%x\n", iova, (unsigned long)paddr,
                        (unsigned long)size, min_pagesz);
                return -EINVAL;
        }

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

        while (size) {
                unsigned long pgsize, addr_merge = iova | paddr;
                unsigned int pgsize_idx;

                /* 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 both iova and paddr */
                        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->ops->pgsize_bitmap;

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

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

                pr_debug("mapping: iova 0x%lx pa 0x%lx pgsize %lu\n", iova,
                                        (unsigned long)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);

        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;

        if (unlikely(domain->ops->unmap == NULL))
                return -ENODEV;

        /* find out the minimum page size supported */
        min_pagesz = 1 << __ffs(domain->ops->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%lx min_pagesz 0x%x\n",
                                        iova, (unsigned long)size, min_pagesz);
                return -EINVAL;
        }

        pr_debug("unmap this: iova 0x%lx size 0x%lx\n", iova,
                                                        (unsigned long)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 left = size - unmapped;

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

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

                iova += unmapped_page;
                unmapped += unmapped_page;
        }

        return unmapped;
}
EXPORT_SYMBOL_GPL(iommu_unmap);

static int __init iommu_init(void)
{
        iommu_group_kset = kset_create_and_add("iommu_groups",
                                               NULL, kernel_kobj);
        ida_init(&iommu_group_ida);
        mutex_init(&iommu_group_mutex);

        BUG_ON(!iommu_group_kset);

        return 0;
}
subsys_initcall(iommu_init);