Merge tag 'rtc-4.10-2' of git://git.kernel.org/pub/scm/linux/kernel/git/abelloni...

[mirror_ubuntu-zesty-kernel.git] / drivers / nvdimm / bus.c

/*
 * Copyright(c) 2013-2015 Intel Corporation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License 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.
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/vmalloc.h>
#include <linux/uaccess.h>
#include <linux/module.h>
#include <linux/blkdev.h>
#include <linux/fcntl.h>
#include <linux/async.h>
#include <linux/genhd.h>
#include <linux/ndctl.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/mm.h>
#include <linux/nd.h>
#include "nd-core.h"
#include "nd.h"

int nvdimm_major;
static int nvdimm_bus_major;
static struct class *nd_class;
static DEFINE_IDA(nd_ida);

static int to_nd_device_type(struct device *dev)
{
        if (is_nvdimm(dev))
                return ND_DEVICE_DIMM;
        else if (is_nd_pmem(dev))
                return ND_DEVICE_REGION_PMEM;
        else if (is_nd_blk(dev))
                return ND_DEVICE_REGION_BLK;
        else if (is_nd_dax(dev))
                return ND_DEVICE_DAX_PMEM;
        else if (is_nd_pmem(dev->parent) || is_nd_blk(dev->parent))
                return nd_region_to_nstype(to_nd_region(dev->parent));

        return 0;
}

static int nvdimm_bus_uevent(struct device *dev, struct kobj_uevent_env *env)
{
        /*
         * Ensure that region devices always have their numa node set as
         * early as possible.
         */
        if (is_nd_pmem(dev) || is_nd_blk(dev))
                set_dev_node(dev, to_nd_region(dev)->numa_node);
        return add_uevent_var(env, "MODALIAS=" ND_DEVICE_MODALIAS_FMT,
                        to_nd_device_type(dev));
}

static struct module *to_bus_provider(struct device *dev)
{
        /* pin bus providers while regions are enabled */
        if (is_nd_pmem(dev) || is_nd_blk(dev)) {
                struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);

                return nvdimm_bus->nd_desc->module;
        }
        return NULL;
}

static void nvdimm_bus_probe_start(struct nvdimm_bus *nvdimm_bus)
{
        nvdimm_bus_lock(&nvdimm_bus->dev);
        nvdimm_bus->probe_active++;
        nvdimm_bus_unlock(&nvdimm_bus->dev);
}

static void nvdimm_bus_probe_end(struct nvdimm_bus *nvdimm_bus)
{
        nvdimm_bus_lock(&nvdimm_bus->dev);
        if (--nvdimm_bus->probe_active == 0)
                wake_up(&nvdimm_bus->probe_wait);
        nvdimm_bus_unlock(&nvdimm_bus->dev);
}

static int nvdimm_bus_probe(struct device *dev)
{
        struct nd_device_driver *nd_drv = to_nd_device_driver(dev->driver);
        struct module *provider = to_bus_provider(dev);
        struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);
        int rc;

        if (!try_module_get(provider))
                return -ENXIO;

        nvdimm_bus_probe_start(nvdimm_bus);
        rc = nd_drv->probe(dev);
        if (rc == 0)
                nd_region_probe_success(nvdimm_bus, dev);
        else
                nd_region_disable(nvdimm_bus, dev);
        nvdimm_bus_probe_end(nvdimm_bus);

        dev_dbg(&nvdimm_bus->dev, "%s.probe(%s) = %d\n", dev->driver->name,
                        dev_name(dev), rc);

        if (rc != 0)
                module_put(provider);
        return rc;
}

static int nvdimm_bus_remove(struct device *dev)
{
        struct nd_device_driver *nd_drv = to_nd_device_driver(dev->driver);
        struct module *provider = to_bus_provider(dev);
        struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);
        int rc = 0;

        if (nd_drv->remove)
                rc = nd_drv->remove(dev);
        nd_region_disable(nvdimm_bus, dev);

        dev_dbg(&nvdimm_bus->dev, "%s.remove(%s) = %d\n", dev->driver->name,
                        dev_name(dev), rc);
        module_put(provider);
        return rc;
}

static void nvdimm_bus_shutdown(struct device *dev)
{
        struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);
        struct nd_device_driver *nd_drv = NULL;

        if (dev->driver)
                nd_drv = to_nd_device_driver(dev->driver);

        if (nd_drv && nd_drv->shutdown) {
                nd_drv->shutdown(dev);
                dev_dbg(&nvdimm_bus->dev, "%s.shutdown(%s)\n",
                                dev->driver->name, dev_name(dev));
        }
}

void nd_device_notify(struct device *dev, enum nvdimm_event event)
{
        device_lock(dev);
        if (dev->driver) {
                struct nd_device_driver *nd_drv;

                nd_drv = to_nd_device_driver(dev->driver);
                if (nd_drv->notify)
                        nd_drv->notify(dev, event);
        }
        device_unlock(dev);
}
EXPORT_SYMBOL(nd_device_notify);

void nvdimm_region_notify(struct nd_region *nd_region, enum nvdimm_event event)
{
        struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(&nd_region->dev);

        if (!nvdimm_bus)
                return;

        /* caller is responsible for holding a reference on the device */
        nd_device_notify(&nd_region->dev, event);
}
EXPORT_SYMBOL_GPL(nvdimm_region_notify);

long nvdimm_clear_poison(struct device *dev, phys_addr_t phys,
                unsigned int len)
{
        struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);
        struct nvdimm_bus_descriptor *nd_desc;
        struct nd_cmd_clear_error clear_err;
        struct nd_cmd_ars_cap ars_cap;
        u32 clear_err_unit, mask;
        int cmd_rc, rc;

        if (!nvdimm_bus)
                return -ENXIO;

        nd_desc = nvdimm_bus->nd_desc;
        /*
         * if ndctl does not exist, it's PMEM_LEGACY and
         * we want to just pretend everything is handled.
         */
        if (!nd_desc->ndctl)
                return len;

        memset(&ars_cap, 0, sizeof(ars_cap));
        ars_cap.address = phys;
        ars_cap.length = len;
        rc = nd_desc->ndctl(nd_desc, NULL, ND_CMD_ARS_CAP, &ars_cap,
                        sizeof(ars_cap), &cmd_rc);
        if (rc < 0)
                return rc;
        if (cmd_rc < 0)
                return cmd_rc;
        clear_err_unit = ars_cap.clear_err_unit;
        if (!clear_err_unit || !is_power_of_2(clear_err_unit))
                return -ENXIO;

        mask = clear_err_unit - 1;
        if ((phys | len) & mask)
                return -ENXIO;
        memset(&clear_err, 0, sizeof(clear_err));
        clear_err.address = phys;
        clear_err.length = len;
        rc = nd_desc->ndctl(nd_desc, NULL, ND_CMD_CLEAR_ERROR, &clear_err,
                        sizeof(clear_err), &cmd_rc);
        if (rc < 0)
                return rc;
        if (cmd_rc < 0)
                return cmd_rc;

        nvdimm_clear_from_poison_list(nvdimm_bus, phys, len);
        return clear_err.cleared;
}
EXPORT_SYMBOL_GPL(nvdimm_clear_poison);

static int nvdimm_bus_match(struct device *dev, struct device_driver *drv);

static struct bus_type nvdimm_bus_type = {
        .name = "nd",
        .uevent = nvdimm_bus_uevent,
        .match = nvdimm_bus_match,
        .probe = nvdimm_bus_probe,
        .remove = nvdimm_bus_remove,
        .shutdown = nvdimm_bus_shutdown,
};

static void nvdimm_bus_release(struct device *dev)
{
        struct nvdimm_bus *nvdimm_bus;

        nvdimm_bus = container_of(dev, struct nvdimm_bus, dev);
        ida_simple_remove(&nd_ida, nvdimm_bus->id);
        kfree(nvdimm_bus);
}

static bool is_nvdimm_bus(struct device *dev)
{
        return dev->release == nvdimm_bus_release;
}

struct nvdimm_bus *walk_to_nvdimm_bus(struct device *nd_dev)
{
        struct device *dev;

        for (dev = nd_dev; dev; dev = dev->parent)
                if (is_nvdimm_bus(dev))
                        break;
        dev_WARN_ONCE(nd_dev, !dev, "invalid dev, not on nd bus\n");
        if (dev)
                return to_nvdimm_bus(dev);
        return NULL;
}

struct nvdimm_bus *to_nvdimm_bus(struct device *dev)
{
        struct nvdimm_bus *nvdimm_bus;

        nvdimm_bus = container_of(dev, struct nvdimm_bus, dev);
        WARN_ON(!is_nvdimm_bus(dev));
        return nvdimm_bus;
}
EXPORT_SYMBOL_GPL(to_nvdimm_bus);

struct nvdimm_bus *nvdimm_bus_register(struct device *parent,
                struct nvdimm_bus_descriptor *nd_desc)
{
        struct nvdimm_bus *nvdimm_bus;
        int rc;

        nvdimm_bus = kzalloc(sizeof(*nvdimm_bus), GFP_KERNEL);
        if (!nvdimm_bus)
                return NULL;
        INIT_LIST_HEAD(&nvdimm_bus->list);
        INIT_LIST_HEAD(&nvdimm_bus->mapping_list);
        INIT_LIST_HEAD(&nvdimm_bus->poison_list);
        init_waitqueue_head(&nvdimm_bus->probe_wait);
        nvdimm_bus->id = ida_simple_get(&nd_ida, 0, 0, GFP_KERNEL);
        mutex_init(&nvdimm_bus->reconfig_mutex);
        if (nvdimm_bus->id < 0) {
                kfree(nvdimm_bus);
                return NULL;
        }
        nvdimm_bus->nd_desc = nd_desc;
        nvdimm_bus->dev.parent = parent;
        nvdimm_bus->dev.release = nvdimm_bus_release;
        nvdimm_bus->dev.groups = nd_desc->attr_groups;
        nvdimm_bus->dev.bus = &nvdimm_bus_type;
        dev_set_name(&nvdimm_bus->dev, "ndbus%d", nvdimm_bus->id);
        rc = device_register(&nvdimm_bus->dev);
        if (rc) {
                dev_dbg(&nvdimm_bus->dev, "registration failed: %d\n", rc);
                goto err;
        }

        return nvdimm_bus;
 err:
        put_device(&nvdimm_bus->dev);
        return NULL;
}
EXPORT_SYMBOL_GPL(nvdimm_bus_register);

void nvdimm_bus_unregister(struct nvdimm_bus *nvdimm_bus)
{
        if (!nvdimm_bus)
                return;
        device_unregister(&nvdimm_bus->dev);
}
EXPORT_SYMBOL_GPL(nvdimm_bus_unregister);

static int child_unregister(struct device *dev, void *data)
{
        /*
         * the singular ndctl class device per bus needs to be
         * "device_destroy"ed, so skip it here
         *
         * i.e. remove classless children
         */
        if (dev->class)
                /* pass */;
        else
                nd_device_unregister(dev, ND_SYNC);
        return 0;
}

static void free_poison_list(struct list_head *poison_list)
{
        struct nd_poison *pl, *next;

        list_for_each_entry_safe(pl, next, poison_list, list) {
                list_del(&pl->list);
                kfree(pl);
        }
        list_del_init(poison_list);
}

static int nd_bus_remove(struct device *dev)
{
        struct nvdimm_bus *nvdimm_bus = to_nvdimm_bus(dev);

        mutex_lock(&nvdimm_bus_list_mutex);
        list_del_init(&nvdimm_bus->list);
        mutex_unlock(&nvdimm_bus_list_mutex);

        nd_synchronize();
        device_for_each_child(&nvdimm_bus->dev, NULL, child_unregister);

        nvdimm_bus_lock(&nvdimm_bus->dev);
        free_poison_list(&nvdimm_bus->poison_list);
        nvdimm_bus_unlock(&nvdimm_bus->dev);

        nvdimm_bus_destroy_ndctl(nvdimm_bus);

        return 0;
}

static int nd_bus_probe(struct device *dev)
{
        struct nvdimm_bus *nvdimm_bus = to_nvdimm_bus(dev);
        int rc;

        rc = nvdimm_bus_create_ndctl(nvdimm_bus);
        if (rc)
                return rc;

        mutex_lock(&nvdimm_bus_list_mutex);
        list_add_tail(&nvdimm_bus->list, &nvdimm_bus_list);
        mutex_unlock(&nvdimm_bus_list_mutex);

        /* enable bus provider attributes to look up their local context */
        dev_set_drvdata(dev, nvdimm_bus->nd_desc);

        return 0;
}

static struct nd_device_driver nd_bus_driver = {
        .probe = nd_bus_probe,
        .remove = nd_bus_remove,
        .drv = {
                .name = "nd_bus",
                .suppress_bind_attrs = true,
                .bus = &nvdimm_bus_type,
                .owner = THIS_MODULE,
                .mod_name = KBUILD_MODNAME,
        },
};

static int nvdimm_bus_match(struct device *dev, struct device_driver *drv)
{
        struct nd_device_driver *nd_drv = to_nd_device_driver(drv);

        if (is_nvdimm_bus(dev) && nd_drv == &nd_bus_driver)
                return true;

        return !!test_bit(to_nd_device_type(dev), &nd_drv->type);
}

static ASYNC_DOMAIN_EXCLUSIVE(nd_async_domain);

void nd_synchronize(void)
{
        async_synchronize_full_domain(&nd_async_domain);
}
EXPORT_SYMBOL_GPL(nd_synchronize);

static void nd_async_device_register(void *d, async_cookie_t cookie)
{
        struct device *dev = d;

        if (device_add(dev) != 0) {
                dev_err(dev, "%s: failed\n", __func__);
                put_device(dev);
        }
        put_device(dev);
}

static void nd_async_device_unregister(void *d, async_cookie_t cookie)
{
        struct device *dev = d;

        /* flush bus operations before delete */
        nvdimm_bus_lock(dev);
        nvdimm_bus_unlock(dev);

        device_unregister(dev);
        put_device(dev);
}

void __nd_device_register(struct device *dev)
{
        if (!dev)
                return;
        dev->bus = &nvdimm_bus_type;
        get_device(dev);
        async_schedule_domain(nd_async_device_register, dev,
                        &nd_async_domain);
}

void nd_device_register(struct device *dev)
{
        device_initialize(dev);
        __nd_device_register(dev);
}
EXPORT_SYMBOL(nd_device_register);

void nd_device_unregister(struct device *dev, enum nd_async_mode mode)
{
        switch (mode) {
        case ND_ASYNC:
                get_device(dev);
                async_schedule_domain(nd_async_device_unregister, dev,
                                &nd_async_domain);
                break;
        case ND_SYNC:
                nd_synchronize();
                device_unregister(dev);
                break;
        }
}
EXPORT_SYMBOL(nd_device_unregister);

/**
 * __nd_driver_register() - register a region or a namespace driver
 * @nd_drv: driver to register
 * @owner: automatically set by nd_driver_register() macro
 * @mod_name: automatically set by nd_driver_register() macro
 */
int __nd_driver_register(struct nd_device_driver *nd_drv, struct module *owner,
                const char *mod_name)
{
        struct device_driver *drv = &nd_drv->drv;

        if (!nd_drv->type) {
                pr_debug("driver type bitmask not set (%pf)\n",
                                __builtin_return_address(0));
                return -EINVAL;
        }

        if (!nd_drv->probe) {
                pr_debug("%s ->probe() must be specified\n", mod_name);
                return -EINVAL;
        }

        drv->bus = &nvdimm_bus_type;
        drv->owner = owner;
        drv->mod_name = mod_name;

        return driver_register(drv);
}
EXPORT_SYMBOL(__nd_driver_register);

int nvdimm_revalidate_disk(struct gendisk *disk)
{
        struct device *dev = disk_to_dev(disk)->parent;
        struct nd_region *nd_region = to_nd_region(dev->parent);
        const char *pol = nd_region->ro ? "only" : "write";

        if (nd_region->ro == get_disk_ro(disk))
                return 0;

        dev_info(dev, "%s read-%s, marking %s read-%s\n",
                        dev_name(&nd_region->dev), pol, disk->disk_name, pol);
        set_disk_ro(disk, nd_region->ro);

        return 0;

}
EXPORT_SYMBOL(nvdimm_revalidate_disk);

static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
                char *buf)
{
        return sprintf(buf, ND_DEVICE_MODALIAS_FMT "\n",
                        to_nd_device_type(dev));
}
static DEVICE_ATTR_RO(modalias);

static ssize_t devtype_show(struct device *dev, struct device_attribute *attr,
                char *buf)
{
        return sprintf(buf, "%s\n", dev->type->name);
}
static DEVICE_ATTR_RO(devtype);

static struct attribute *nd_device_attributes[] = {
        &dev_attr_modalias.attr,
        &dev_attr_devtype.attr,
        NULL,
};

/**
 * nd_device_attribute_group - generic attributes for all devices on an nd bus
 */
struct attribute_group nd_device_attribute_group = {
        .attrs = nd_device_attributes,
};
EXPORT_SYMBOL_GPL(nd_device_attribute_group);

static ssize_t numa_node_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        return sprintf(buf, "%d\n", dev_to_node(dev));
}
static DEVICE_ATTR_RO(numa_node);

static struct attribute *nd_numa_attributes[] = {
        &dev_attr_numa_node.attr,
        NULL,
};

static umode_t nd_numa_attr_visible(struct kobject *kobj, struct attribute *a,
                int n)
{
        if (!IS_ENABLED(CONFIG_NUMA))
                return 0;

        return a->mode;
}

/**
 * nd_numa_attribute_group - NUMA attributes for all devices on an nd bus
 */
struct attribute_group nd_numa_attribute_group = {
        .attrs = nd_numa_attributes,
        .is_visible = nd_numa_attr_visible,
};
EXPORT_SYMBOL_GPL(nd_numa_attribute_group);

int nvdimm_bus_create_ndctl(struct nvdimm_bus *nvdimm_bus)
{
        dev_t devt = MKDEV(nvdimm_bus_major, nvdimm_bus->id);
        struct device *dev;

        dev = device_create(nd_class, &nvdimm_bus->dev, devt, nvdimm_bus,
                        "ndctl%d", nvdimm_bus->id);

        if (IS_ERR(dev))
                dev_dbg(&nvdimm_bus->dev, "failed to register ndctl%d: %ld\n",
                                nvdimm_bus->id, PTR_ERR(dev));
        return PTR_ERR_OR_ZERO(dev);
}

void nvdimm_bus_destroy_ndctl(struct nvdimm_bus *nvdimm_bus)
{
        device_destroy(nd_class, MKDEV(nvdimm_bus_major, nvdimm_bus->id));
}

static const struct nd_cmd_desc __nd_cmd_dimm_descs[] = {
        [ND_CMD_IMPLEMENTED] = { },
        [ND_CMD_SMART] = {
                .out_num = 2,
                .out_sizes = { 4, 128, },
        },
        [ND_CMD_SMART_THRESHOLD] = {
                .out_num = 2,
                .out_sizes = { 4, 8, },
        },
        [ND_CMD_DIMM_FLAGS] = {
                .out_num = 2,
                .out_sizes = { 4, 4 },
        },
        [ND_CMD_GET_CONFIG_SIZE] = {
                .out_num = 3,
                .out_sizes = { 4, 4, 4, },
        },
        [ND_CMD_GET_CONFIG_DATA] = {
                .in_num = 2,
                .in_sizes = { 4, 4, },
                .out_num = 2,
                .out_sizes = { 4, UINT_MAX, },
        },
        [ND_CMD_SET_CONFIG_DATA] = {
                .in_num = 3,
                .in_sizes = { 4, 4, UINT_MAX, },
                .out_num = 1,
                .out_sizes = { 4, },
        },
        [ND_CMD_VENDOR] = {
                .in_num = 3,
                .in_sizes = { 4, 4, UINT_MAX, },
                .out_num = 3,
                .out_sizes = { 4, 4, UINT_MAX, },
        },
        [ND_CMD_CALL] = {
                .in_num = 2,
                .in_sizes = { sizeof(struct nd_cmd_pkg), UINT_MAX, },
                .out_num = 1,
                .out_sizes = { UINT_MAX, },
        },
};

const struct nd_cmd_desc *nd_cmd_dimm_desc(int cmd)
{
        if (cmd < ARRAY_SIZE(__nd_cmd_dimm_descs))
                return &__nd_cmd_dimm_descs[cmd];
        return NULL;
}
EXPORT_SYMBOL_GPL(nd_cmd_dimm_desc);

static const struct nd_cmd_desc __nd_cmd_bus_descs[] = {
        [ND_CMD_IMPLEMENTED] = { },
        [ND_CMD_ARS_CAP] = {
                .in_num = 2,
                .in_sizes = { 8, 8, },
                .out_num = 4,
                .out_sizes = { 4, 4, 4, 4, },
        },
        [ND_CMD_ARS_START] = {
                .in_num = 5,
                .in_sizes = { 8, 8, 2, 1, 5, },
                .out_num = 2,
                .out_sizes = { 4, 4, },
        },
        [ND_CMD_ARS_STATUS] = {
                .out_num = 3,
                .out_sizes = { 4, 4, UINT_MAX, },
        },
        [ND_CMD_CLEAR_ERROR] = {
                .in_num = 2,
                .in_sizes = { 8, 8, },
                .out_num = 3,
                .out_sizes = { 4, 4, 8, },
        },
        [ND_CMD_CALL] = {
                .in_num = 2,
                .in_sizes = { sizeof(struct nd_cmd_pkg), UINT_MAX, },
                .out_num = 1,
                .out_sizes = { UINT_MAX, },
        },
};

const struct nd_cmd_desc *nd_cmd_bus_desc(int cmd)
{
        if (cmd < ARRAY_SIZE(__nd_cmd_bus_descs))
                return &__nd_cmd_bus_descs[cmd];
        return NULL;
}
EXPORT_SYMBOL_GPL(nd_cmd_bus_desc);

u32 nd_cmd_in_size(struct nvdimm *nvdimm, int cmd,
                const struct nd_cmd_desc *desc, int idx, void *buf)
{
        if (idx >= desc->in_num)
                return UINT_MAX;

        if (desc->in_sizes[idx] < UINT_MAX)
                return desc->in_sizes[idx];

        if (nvdimm && cmd == ND_CMD_SET_CONFIG_DATA && idx == 2) {
                struct nd_cmd_set_config_hdr *hdr = buf;

                return hdr->in_length;
        } else if (nvdimm && cmd == ND_CMD_VENDOR && idx == 2) {
                struct nd_cmd_vendor_hdr *hdr = buf;

                return hdr->in_length;
        } else if (cmd == ND_CMD_CALL) {
                struct nd_cmd_pkg *pkg = buf;

                return pkg->nd_size_in;
        }

        return UINT_MAX;
}
EXPORT_SYMBOL_GPL(nd_cmd_in_size);

u32 nd_cmd_out_size(struct nvdimm *nvdimm, int cmd,
                const struct nd_cmd_desc *desc, int idx, const u32 *in_field,
                const u32 *out_field, unsigned long remainder)
{
        if (idx >= desc->out_num)
                return UINT_MAX;

        if (desc->out_sizes[idx] < UINT_MAX)
                return desc->out_sizes[idx];

        if (nvdimm && cmd == ND_CMD_GET_CONFIG_DATA && idx == 1)
                return in_field[1];
        else if (nvdimm && cmd == ND_CMD_VENDOR && idx == 2)
                return out_field[1];
        else if (!nvdimm && cmd == ND_CMD_ARS_STATUS && idx == 2) {
                /*
                 * Per table 9-276 ARS Data in ACPI 6.1, out_field[1] is
                 * "Size of Output Buffer in bytes, including this
                 * field."
                 */
                if (out_field[1] < 4)
                        return 0;
                /*
                 * ACPI 6.1 is ambiguous if 'status' is included in the
                 * output size. If we encounter an output size that
                 * overshoots the remainder by 4 bytes, assume it was
                 * including 'status'.
                 */
                if (out_field[1] - 8 == remainder)
                        return remainder;
                return out_field[1] - 4;
        } else if (cmd == ND_CMD_CALL) {
                struct nd_cmd_pkg *pkg = (struct nd_cmd_pkg *) in_field;

                return pkg->nd_size_out;
        }


        return UINT_MAX;
}
EXPORT_SYMBOL_GPL(nd_cmd_out_size);

void wait_nvdimm_bus_probe_idle(struct device *dev)
{
        struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(dev);

        do {
                if (nvdimm_bus->probe_active == 0)
                        break;
                nvdimm_bus_unlock(&nvdimm_bus->dev);
                wait_event(nvdimm_bus->probe_wait,
                                nvdimm_bus->probe_active == 0);
                nvdimm_bus_lock(&nvdimm_bus->dev);
        } while (true);
}

static int pmem_active(struct device *dev, void *data)
{
        if (is_nd_pmem(dev) && dev->driver)
                return -EBUSY;
        return 0;
}

/* set_config requires an idle interleave set */
static int nd_cmd_clear_to_send(struct nvdimm_bus *nvdimm_bus,
                struct nvdimm *nvdimm, unsigned int cmd)
{
        struct nvdimm_bus_descriptor *nd_desc = nvdimm_bus->nd_desc;

        /* ask the bus provider if it would like to block this request */
        if (nd_desc->clear_to_send) {
                int rc = nd_desc->clear_to_send(nd_desc, nvdimm, cmd);

                if (rc)
                        return rc;
        }

        /* require clear error to go through the pmem driver */
        if (!nvdimm && cmd == ND_CMD_CLEAR_ERROR)
                return device_for_each_child(&nvdimm_bus->dev, NULL,
                                pmem_active);

        if (!nvdimm || cmd != ND_CMD_SET_CONFIG_DATA)
                return 0;

        /* prevent label manipulation while the kernel owns label updates */
        wait_nvdimm_bus_probe_idle(&nvdimm_bus->dev);
        if (atomic_read(&nvdimm->busy))
                return -EBUSY;
        return 0;
}

static int __nd_ioctl(struct nvdimm_bus *nvdimm_bus, struct nvdimm *nvdimm,
                int read_only, unsigned int ioctl_cmd, unsigned long arg)
{
        struct nvdimm_bus_descriptor *nd_desc = nvdimm_bus->nd_desc;
        size_t buf_len = 0, in_len = 0, out_len = 0;
        static char out_env[ND_CMD_MAX_ENVELOPE];
        static char in_env[ND_CMD_MAX_ENVELOPE];
        const struct nd_cmd_desc *desc = NULL;
        unsigned int cmd = _IOC_NR(ioctl_cmd);
        void __user *p = (void __user *) arg;
        struct device *dev = &nvdimm_bus->dev;
        struct nd_cmd_pkg pkg;
        const char *cmd_name, *dimm_name;
        unsigned long cmd_mask;
        void *buf;
        int rc, i;

        if (nvdimm) {
                desc = nd_cmd_dimm_desc(cmd);
                cmd_name = nvdimm_cmd_name(cmd);
                cmd_mask = nvdimm->cmd_mask;
                dimm_name = dev_name(&nvdimm->dev);
        } else {
                desc = nd_cmd_bus_desc(cmd);
                cmd_name = nvdimm_bus_cmd_name(cmd);
                cmd_mask = nd_desc->cmd_mask;
                dimm_name = "bus";
        }

        if (cmd == ND_CMD_CALL) {
                if (copy_from_user(&pkg, p, sizeof(pkg)))
                        return -EFAULT;
        }

        if (!desc || (desc->out_num + desc->in_num == 0) ||
                        !test_bit(cmd, &cmd_mask))
                return -ENOTTY;

        /* fail write commands (when read-only) */
        if (read_only)
                switch (cmd) {
                case ND_CMD_VENDOR:
                case ND_CMD_SET_CONFIG_DATA:
                case ND_CMD_ARS_START:
                case ND_CMD_CLEAR_ERROR:
                case ND_CMD_CALL:
                        dev_dbg(&nvdimm_bus->dev, "'%s' command while read-only.\n",
                                        nvdimm ? nvdimm_cmd_name(cmd)
                                        : nvdimm_bus_cmd_name(cmd));
                        return -EPERM;
                default:
                        break;
                }

        /* process an input envelope */
        for (i = 0; i < desc->in_num; i++) {
                u32 in_size, copy;

                in_size = nd_cmd_in_size(nvdimm, cmd, desc, i, in_env);
                if (in_size == UINT_MAX) {
                        dev_err(dev, "%s:%s unknown input size cmd: %s field: %d\n",
                                        __func__, dimm_name, cmd_name, i);
                        return -ENXIO;
                }
                if (in_len < sizeof(in_env))
                        copy = min_t(u32, sizeof(in_env) - in_len, in_size);
                else
                        copy = 0;
                if (copy && copy_from_user(&in_env[in_len], p + in_len, copy))
                        return -EFAULT;
                in_len += in_size;
        }

        if (cmd == ND_CMD_CALL) {
                dev_dbg(dev, "%s:%s, idx: %llu, in: %zu, out: %zu, len %zu\n",
                                __func__, dimm_name, pkg.nd_command,
                                in_len, out_len, buf_len);

                for (i = 0; i < ARRAY_SIZE(pkg.nd_reserved2); i++)
                        if (pkg.nd_reserved2[i])
                                return -EINVAL;
        }

        /* process an output envelope */
        for (i = 0; i < desc->out_num; i++) {
                u32 out_size = nd_cmd_out_size(nvdimm, cmd, desc, i,
                                (u32 *) in_env, (u32 *) out_env, 0);
                u32 copy;

                if (out_size == UINT_MAX) {
                        dev_dbg(dev, "%s:%s unknown output size cmd: %s field: %d\n",
                                        __func__, dimm_name, cmd_name, i);
                        return -EFAULT;
                }
                if (out_len < sizeof(out_env))
                        copy = min_t(u32, sizeof(out_env) - out_len, out_size);
                else
                        copy = 0;
                if (copy && copy_from_user(&out_env[out_len],
                                        p + in_len + out_len, copy))
                        return -EFAULT;
                out_len += out_size;
        }

        buf_len = out_len + in_len;
        if (buf_len > ND_IOCTL_MAX_BUFLEN) {
                dev_dbg(dev, "%s:%s cmd: %s buf_len: %zu > %d\n", __func__,
                                dimm_name, cmd_name, buf_len,
                                ND_IOCTL_MAX_BUFLEN);
                return -EINVAL;
        }

        buf = vmalloc(buf_len);
        if (!buf)
                return -ENOMEM;

        if (copy_from_user(buf, p, buf_len)) {
                rc = -EFAULT;
                goto out;
        }

        nvdimm_bus_lock(&nvdimm_bus->dev);
        rc = nd_cmd_clear_to_send(nvdimm_bus, nvdimm, cmd);
        if (rc)
                goto out_unlock;

        rc = nd_desc->ndctl(nd_desc, nvdimm, cmd, buf, buf_len, NULL);
        if (rc < 0)
                goto out_unlock;
        if (copy_to_user(p, buf, buf_len))
                rc = -EFAULT;
 out_unlock:
        nvdimm_bus_unlock(&nvdimm_bus->dev);
 out:
        vfree(buf);
        return rc;
}

static long nd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
        long id = (long) file->private_data;
        int rc = -ENXIO, ro;
        struct nvdimm_bus *nvdimm_bus;

        ro = ((file->f_flags & O_ACCMODE) == O_RDONLY);
        mutex_lock(&nvdimm_bus_list_mutex);
        list_for_each_entry(nvdimm_bus, &nvdimm_bus_list, list) {
                if (nvdimm_bus->id == id) {
                        rc = __nd_ioctl(nvdimm_bus, NULL, ro, cmd, arg);
                        break;
                }
        }
        mutex_unlock(&nvdimm_bus_list_mutex);

        return rc;
}

static int match_dimm(struct device *dev, void *data)
{
        long id = (long) data;

        if (is_nvdimm(dev)) {
                struct nvdimm *nvdimm = to_nvdimm(dev);

                return nvdimm->id == id;
        }

        return 0;
}

static long nvdimm_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
        int rc = -ENXIO, ro;
        struct nvdimm_bus *nvdimm_bus;

        ro = ((file->f_flags & O_ACCMODE) == O_RDONLY);
        mutex_lock(&nvdimm_bus_list_mutex);
        list_for_each_entry(nvdimm_bus, &nvdimm_bus_list, list) {
                struct device *dev = device_find_child(&nvdimm_bus->dev,
                                file->private_data, match_dimm);
                struct nvdimm *nvdimm;

                if (!dev)
                        continue;

                nvdimm = to_nvdimm(dev);
                rc = __nd_ioctl(nvdimm_bus, nvdimm, ro, cmd, arg);
                put_device(dev);
                break;
        }
        mutex_unlock(&nvdimm_bus_list_mutex);

        return rc;
}

static int nd_open(struct inode *inode, struct file *file)
{
        long minor = iminor(inode);

        file->private_data = (void *) minor;
        return 0;
}

static const struct file_operations nvdimm_bus_fops = {
        .owner = THIS_MODULE,
        .open = nd_open,
        .unlocked_ioctl = nd_ioctl,
        .compat_ioctl = nd_ioctl,
        .llseek = noop_llseek,
};

static const struct file_operations nvdimm_fops = {
        .owner = THIS_MODULE,
        .open = nd_open,
        .unlocked_ioctl = nvdimm_ioctl,
        .compat_ioctl = nvdimm_ioctl,
        .llseek = noop_llseek,
};

int __init nvdimm_bus_init(void)
{
        int rc;

        BUILD_BUG_ON(sizeof(struct nd_smart_payload) != 128);
        BUILD_BUG_ON(sizeof(struct nd_smart_threshold_payload) != 8);

        rc = bus_register(&nvdimm_bus_type);
        if (rc)
                return rc;

        rc = register_chrdev(0, "ndctl", &nvdimm_bus_fops);
        if (rc < 0)
                goto err_bus_chrdev;
        nvdimm_bus_major = rc;

        rc = register_chrdev(0, "dimmctl", &nvdimm_fops);
        if (rc < 0)
                goto err_dimm_chrdev;
        nvdimm_major = rc;

        nd_class = class_create(THIS_MODULE, "nd");
        if (IS_ERR(nd_class)) {
                rc = PTR_ERR(nd_class);
                goto err_class;
        }

        rc = driver_register(&nd_bus_driver.drv);
        if (rc)
                goto err_nd_bus;

        return 0;

 err_nd_bus:
        class_destroy(nd_class);
 err_class:
        unregister_chrdev(nvdimm_major, "dimmctl");
 err_dimm_chrdev:
        unregister_chrdev(nvdimm_bus_major, "ndctl");
 err_bus_chrdev:
        bus_unregister(&nvdimm_bus_type);

        return rc;
}

void nvdimm_bus_exit(void)
{
        driver_unregister(&nd_bus_driver.drv);
        class_destroy(nd_class);
        unregister_chrdev(nvdimm_bus_major, "ndctl");
        unregister_chrdev(nvdimm_major, "dimmctl");
        bus_unregister(&nvdimm_bus_type);
        ida_destroy(&nd_ida);
}