/*
 * 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.
 */
#include <linux/device.h>
#include <linux/sizes.h>
#include <linux/pmem.h>
#include "nd-core.h"
#include "pfn.h"
#include "btt.h"
#include "nd.h"

void __nd_detach_ndns(struct device *dev, struct nd_namespace_common **_ndns)
{
        struct nd_namespace_common *ndns = *_ndns;

        dev_WARN_ONCE(dev, !mutex_is_locked(&ndns->dev.mutex)
                        || ndns->claim != dev,
                        "%s: invalid claim\n", __func__);
        ndns->claim = NULL;
        *_ndns = NULL;
        put_device(&ndns->dev);
}

void nd_detach_ndns(struct device *dev,
                struct nd_namespace_common **_ndns)
{
        struct nd_namespace_common *ndns = *_ndns;

        if (!ndns)
                return;
        get_device(&ndns->dev);
        device_lock(&ndns->dev);
        __nd_detach_ndns(dev, _ndns);
        device_unlock(&ndns->dev);
        put_device(&ndns->dev);
}

bool __nd_attach_ndns(struct device *dev, struct nd_namespace_common *attach,
                struct nd_namespace_common **_ndns)
{
        if (attach->claim)
                return false;
        dev_WARN_ONCE(dev, !mutex_is_locked(&attach->dev.mutex)
                        || *_ndns,
                        "%s: invalid claim\n", __func__);
        attach->claim = dev;
        *_ndns = attach;
        get_device(&attach->dev);
        return true;
}

bool nd_attach_ndns(struct device *dev, struct nd_namespace_common *attach,
                struct nd_namespace_common **_ndns)
{
        bool claimed;

        device_lock(&attach->dev);
        claimed = __nd_attach_ndns(dev, attach, _ndns);
        device_unlock(&attach->dev);
        return claimed;
}

static int namespace_match(struct device *dev, void *data)
{
        char *name = data;

        return strcmp(name, dev_name(dev)) == 0;
}

static bool is_idle(struct device *dev, struct nd_namespace_common *ndns)
{
        struct nd_region *nd_region = to_nd_region(dev->parent);
        struct device *seed = NULL;

        if (is_nd_btt(dev))
                seed = nd_region->btt_seed;
        else if (is_nd_pfn(dev))
                seed = nd_region->pfn_seed;
        else if (is_nd_dax(dev))
                seed = nd_region->dax_seed;

        if (seed == dev || ndns || dev->driver)
                return false;
        return true;
}

struct nd_pfn *to_nd_pfn_safe(struct device *dev)
{
        /*
         * pfn device attributes are re-used by dax device instances, so we
         * need to be careful to correct device-to-nd_pfn conversion.
         */
        if (is_nd_pfn(dev))
                return to_nd_pfn(dev);

        if (is_nd_dax(dev)) {
                struct nd_dax *nd_dax = to_nd_dax(dev);

                return &nd_dax->nd_pfn;
        }

        WARN_ON(1);
        return NULL;
}

static void nd_detach_and_reset(struct device *dev,
                struct nd_namespace_common **_ndns)
{
        /* detach the namespace and destroy / reset the device */
        nd_detach_ndns(dev, _ndns);
        if (is_idle(dev, *_ndns)) {
                nd_device_unregister(dev, ND_ASYNC);
        } else if (is_nd_btt(dev)) {
                struct nd_btt *nd_btt = to_nd_btt(dev);

                nd_btt->lbasize = 0;
                kfree(nd_btt->uuid);
                nd_btt->uuid = NULL;
        } else if (is_nd_pfn(dev) || is_nd_dax(dev)) {
                struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);

                kfree(nd_pfn->uuid);
                nd_pfn->uuid = NULL;
                nd_pfn->mode = PFN_MODE_NONE;
        }
}

ssize_t nd_namespace_store(struct device *dev,
                struct nd_namespace_common **_ndns, const char *buf,
                size_t len)
{
        struct nd_namespace_common *ndns;
        struct device *found;
        char *name;

        if (dev->driver) {
                dev_dbg(dev, "%s: -EBUSY\n", __func__);
                return -EBUSY;
        }

        name = kstrndup(buf, len, GFP_KERNEL);
        if (!name)
                return -ENOMEM;
        strim(name);

        if (strncmp(name, "namespace", 9) == 0 || strcmp(name, "") == 0)
                /* pass */;
        else {
                len = -EINVAL;
                goto out;
        }

        ndns = *_ndns;
        if (strcmp(name, "") == 0) {
                nd_detach_and_reset(dev, _ndns);
                goto out;
        } else if (ndns) {
                dev_dbg(dev, "namespace already set to: %s\n",
                                dev_name(&ndns->dev));
                len = -EBUSY;
                goto out;
        }

        found = device_find_child(dev->parent, name, namespace_match);
        if (!found) {
                dev_dbg(dev, "'%s' not found under %s\n", name,
                                dev_name(dev->parent));
                len = -ENODEV;
                goto out;
        }

        ndns = to_ndns(found);
        if (__nvdimm_namespace_capacity(ndns) < SZ_16M) {
                dev_dbg(dev, "%s too small to host\n", name);
                len = -ENXIO;
                goto out_attach;
        }

        WARN_ON_ONCE(!is_nvdimm_bus_locked(dev));
        if (!nd_attach_ndns(dev, ndns, _ndns)) {
                dev_dbg(dev, "%s already claimed\n",
                                dev_name(&ndns->dev));
                len = -EBUSY;
        }

 out_attach:
        put_device(&ndns->dev); /* from device_find_child */
 out:
        kfree(name);
        return len;
}

/*
 * nd_sb_checksum: compute checksum for a generic info block
 *
 * Returns a fletcher64 checksum of everything in the given info block
 * except the last field (since that's where the checksum lives).
 */
u64 nd_sb_checksum(struct nd_gen_sb *nd_gen_sb)
{
        u64 sum;
        __le64 sum_save;

        BUILD_BUG_ON(sizeof(struct btt_sb) != SZ_4K);
        BUILD_BUG_ON(sizeof(struct nd_pfn_sb) != SZ_4K);
        BUILD_BUG_ON(sizeof(struct nd_gen_sb) != SZ_4K);

        sum_save = nd_gen_sb->checksum;
        nd_gen_sb->checksum = 0;
        sum = nd_fletcher64(nd_gen_sb, sizeof(*nd_gen_sb), 1);
        nd_gen_sb->checksum = sum_save;
        return sum;
}
EXPORT_SYMBOL(nd_sb_checksum);

static int nsio_rw_bytes(struct nd_namespace_common *ndns,
                resource_size_t offset, void *buf, size_t size, int rw)
{
        struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);

        if (unlikely(offset + size > nsio->size)) {
                dev_WARN_ONCE(&ndns->dev, 1, "request out of range\n");
                return -EFAULT;
        }

        if (rw == READ) {
                unsigned int sz_align = ALIGN(size + (offset & (512 - 1)), 512);

                if (unlikely(is_bad_pmem(&nsio->bb, offset / 512, sz_align)))
                        return -EIO;
                return memcpy_from_pmem(buf, nsio->addr + offset, size);
        } else {
                memcpy_to_pmem(nsio->addr + offset, buf, size);
                nvdimm_flush(to_nd_region(ndns->dev.parent));
        }

        return 0;
}

int devm_nsio_enable(struct device *dev, struct nd_namespace_io *nsio)
{
        struct resource *res = &nsio->res;
        struct nd_namespace_common *ndns = &nsio->common;

        nsio->size = resource_size(res);
        if (!devm_request_mem_region(dev, res->start, resource_size(res),
                                dev_name(dev))) {
                dev_warn(dev, "could not reserve region %pR\n", res);
                return -EBUSY;
        }

        ndns->rw_bytes = nsio_rw_bytes;
        if (devm_init_badblocks(dev, &nsio->bb))
                return -ENOMEM;
        nvdimm_badblocks_populate(to_nd_region(ndns->dev.parent), &nsio->bb,
                        &nsio->res);

        nsio->addr = devm_memremap(dev, res->start, resource_size(res),
                        ARCH_MEMREMAP_PMEM);

        return PTR_ERR_OR_ZERO(nsio->addr);
}
EXPORT_SYMBOL_GPL(devm_nsio_enable);

void devm_nsio_disable(struct device *dev, struct nd_namespace_io *nsio)
{
        struct resource *res = &nsio->res;

        devm_memunmap(dev, nsio->addr);
        devm_exit_badblocks(dev, &nsio->bb);
        devm_release_mem_region(dev, res->start, resource_size(res));
}
EXPORT_SYMBOL_GPL(devm_nsio_disable);