/*
 * 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/blkdev.h>
#include <linux/device.h>
#include <linux/genhd.h>
#include <linux/sizes.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include "nd-core.h"
#include "btt.h"
#include "nd.h"

static void nd_btt_release(struct device *dev)
{
        struct nd_region *nd_region = to_nd_region(dev->parent);
        struct nd_btt *nd_btt = to_nd_btt(dev);

        dev_dbg(dev, "%s\n", __func__);
        nd_detach_ndns(&nd_btt->dev, &nd_btt->ndns);
        ida_simple_remove(&nd_region->btt_ida, nd_btt->id);
        kfree(nd_btt->uuid);
        kfree(nd_btt);
}

static struct device_type nd_btt_device_type = {
        .name = "nd_btt",
        .release = nd_btt_release,
};

bool is_nd_btt(struct device *dev)
{
        return dev->type == &nd_btt_device_type;
}
EXPORT_SYMBOL(is_nd_btt);

struct nd_btt *to_nd_btt(struct device *dev)
{
        struct nd_btt *nd_btt = container_of(dev, struct nd_btt, dev);

        WARN_ON(!is_nd_btt(dev));
        return nd_btt;
}
EXPORT_SYMBOL(to_nd_btt);

static const unsigned long btt_lbasize_supported[] = { 512, 520, 528,
        4096, 4104, 4160, 4224, 0 };

static ssize_t sector_size_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct nd_btt *nd_btt = to_nd_btt(dev);

        return nd_sector_size_show(nd_btt->lbasize, btt_lbasize_supported, buf);
}

static ssize_t sector_size_store(struct device *dev,
                struct device_attribute *attr, const char *buf, size_t len)
{
        struct nd_btt *nd_btt = to_nd_btt(dev);
        ssize_t rc;

        device_lock(dev);
        nvdimm_bus_lock(dev);
        rc = nd_sector_size_store(dev, buf, &nd_btt->lbasize,
                        btt_lbasize_supported);
        dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
                        rc, buf, buf[len - 1] == '\n' ? "" : "\n");
        nvdimm_bus_unlock(dev);
        device_unlock(dev);

        return rc ? rc : len;
}
static DEVICE_ATTR_RW(sector_size);

static ssize_t uuid_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct nd_btt *nd_btt = to_nd_btt(dev);

        if (nd_btt->uuid)
                return sprintf(buf, "%pUb\n", nd_btt->uuid);
        return sprintf(buf, "\n");
}

static ssize_t uuid_store(struct device *dev,
                struct device_attribute *attr, const char *buf, size_t len)
{
        struct nd_btt *nd_btt = to_nd_btt(dev);
        ssize_t rc;

        device_lock(dev);
        rc = nd_uuid_store(dev, &nd_btt->uuid, buf, len);
        dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
                        rc, buf, buf[len - 1] == '\n' ? "" : "\n");
        device_unlock(dev);

        return rc ? rc : len;
}
static DEVICE_ATTR_RW(uuid);

static ssize_t namespace_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct nd_btt *nd_btt = to_nd_btt(dev);
        ssize_t rc;

        nvdimm_bus_lock(dev);
        rc = sprintf(buf, "%s\n", nd_btt->ndns
                        ? dev_name(&nd_btt->ndns->dev) : "");
        nvdimm_bus_unlock(dev);
        return rc;
}

static ssize_t namespace_store(struct device *dev,
                struct device_attribute *attr, const char *buf, size_t len)
{
        struct nd_btt *nd_btt = to_nd_btt(dev);
        ssize_t rc;

        device_lock(dev);
        nvdimm_bus_lock(dev);
        rc = nd_namespace_store(dev, &nd_btt->ndns, buf, len);
        dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
                        rc, buf, buf[len - 1] == '\n' ? "" : "\n");
        nvdimm_bus_unlock(dev);
        device_unlock(dev);

        return rc;
}
static DEVICE_ATTR_RW(namespace);

static struct attribute *nd_btt_attributes[] = {
        &dev_attr_sector_size.attr,
        &dev_attr_namespace.attr,
        &dev_attr_uuid.attr,
        NULL,
};

static struct attribute_group nd_btt_attribute_group = {
        .attrs = nd_btt_attributes,
};

static const struct attribute_group *nd_btt_attribute_groups[] = {
        &nd_btt_attribute_group,
        &nd_device_attribute_group,
        &nd_numa_attribute_group,
        NULL,
};

static struct device *__nd_btt_create(struct nd_region *nd_region,
                unsigned long lbasize, u8 *uuid,
                struct nd_namespace_common *ndns)
{
        struct nd_btt *nd_btt;
        struct device *dev;

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

        nd_btt->id = ida_simple_get(&nd_region->btt_ida, 0, 0, GFP_KERNEL);
        if (nd_btt->id < 0) {
                kfree(nd_btt);
                return NULL;
        }

        nd_btt->lbasize = lbasize;
        if (uuid)
                uuid = kmemdup(uuid, 16, GFP_KERNEL);
        nd_btt->uuid = uuid;
        dev = &nd_btt->dev;
        dev_set_name(dev, "btt%d.%d", nd_region->id, nd_btt->id);
        dev->parent = &nd_region->dev;
        dev->type = &nd_btt_device_type;
        dev->groups = nd_btt_attribute_groups;
        device_initialize(&nd_btt->dev);
        if (ndns && !__nd_attach_ndns(&nd_btt->dev, ndns, &nd_btt->ndns)) {
                dev_dbg(&ndns->dev, "%s failed, already claimed by %s\n",
                                __func__, dev_name(ndns->claim));
                put_device(dev);
                return NULL;
        }
        return dev;
}

struct device *nd_btt_create(struct nd_region *nd_region)
{
        struct device *dev = __nd_btt_create(nd_region, 0, NULL, NULL);

        if (dev)
                __nd_device_register(dev);
        return dev;
}

static bool uuid_is_null(u8 *uuid)
{
        static const u8 null_uuid[16];

        return (memcmp(uuid, null_uuid, 16) == 0);
}

/**
 * nd_btt_arena_is_valid - check if the metadata layout is valid
 * @nd_btt:     device with BTT geometry and backing device info
 * @super:      pointer to the arena's info block being tested
 *
 * Check consistency of the btt info block with itself by validating
 * the checksum, and with the parent namespace by verifying the
 * parent_uuid contained in the info block with the one supplied in.
 *
 * Returns:
 * false for an invalid info block, true for a valid one
 */
bool nd_btt_arena_is_valid(struct nd_btt *nd_btt, struct btt_sb *super)
{
        const u8 *parent_uuid = nd_dev_to_uuid(&nd_btt->ndns->dev);
        u64 checksum;

        if (memcmp(super->signature, BTT_SIG, BTT_SIG_LEN) != 0)
                return false;

        if (!uuid_is_null(super->parent_uuid))
                if (memcmp(super->parent_uuid, parent_uuid, 16) != 0)
                        return false;

        checksum = le64_to_cpu(super->checksum);
        super->checksum = 0;
        if (checksum != nd_sb_checksum((struct nd_gen_sb *) super))
                return false;
        super->checksum = cpu_to_le64(checksum);

        /* TODO: figure out action for this */
        if ((le32_to_cpu(super->flags) & IB_FLAG_ERROR_MASK) != 0)
                dev_info(&nd_btt->dev, "Found arena with an error flag\n");

        return true;
}
EXPORT_SYMBOL(nd_btt_arena_is_valid);

static int __nd_btt_probe(struct nd_btt *nd_btt,
                struct nd_namespace_common *ndns, struct btt_sb *btt_sb)
{
        if (!btt_sb || !ndns || !nd_btt)
                return -ENODEV;

        if (nvdimm_read_bytes(ndns, SZ_4K, btt_sb, sizeof(*btt_sb)))
                return -ENXIO;

        if (nvdimm_namespace_capacity(ndns) < SZ_16M)
                return -ENXIO;

        if (!nd_btt_arena_is_valid(nd_btt, btt_sb))
                return -ENODEV;

        nd_btt->lbasize = le32_to_cpu(btt_sb->external_lbasize);
        nd_btt->uuid = kmemdup(btt_sb->uuid, 16, GFP_KERNEL);
        if (!nd_btt->uuid)
                return -ENOMEM;

        __nd_device_register(&nd_btt->dev);

        return 0;
}

int nd_btt_probe(struct nd_namespace_common *ndns, void *drvdata)
{
        int rc;
        struct device *dev;
        struct btt_sb *btt_sb;
        struct nd_region *nd_region = to_nd_region(ndns->dev.parent);

        if (ndns->force_raw)
                return -ENODEV;

        nvdimm_bus_lock(&ndns->dev);
        dev = __nd_btt_create(nd_region, 0, NULL, ndns);
        nvdimm_bus_unlock(&ndns->dev);
        if (!dev)
                return -ENOMEM;
        dev_set_drvdata(dev, drvdata);
        btt_sb = kzalloc(sizeof(*btt_sb), GFP_KERNEL);
        rc = __nd_btt_probe(to_nd_btt(dev), ndns, btt_sb);
        kfree(btt_sb);
        dev_dbg(&ndns->dev, "%s: btt: %s\n", __func__,
                        rc == 0 ? dev_name(dev) : "<none>");
        if (rc < 0) {
                struct nd_btt *nd_btt = to_nd_btt(dev);

                __nd_detach_ndns(dev, &nd_btt->ndns);
                put_device(dev);
        }

        return rc;
}
EXPORT_SYMBOL(nd_btt_probe);