/*
 * Copyright (C) 2015 Matias Bjorling <m@bjorling.me>
 *
 * 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; see the file COPYING.  If not, write to
 * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139,
 * USA.
 *
 * Implementation of a general nvm manager for Open-Channel SSDs.
 */

#include "gennvm.h"

static struct nvm_target *gen_find_target(struct gen_dev *gn, const char *name)
{
        struct nvm_target *tgt;

        list_for_each_entry(tgt, &gn->targets, list)
                if (!strcmp(name, tgt->disk->disk_name))
                        return tgt;

        return NULL;
}

static const struct block_device_operations gen_fops = {
        .owner          = THIS_MODULE,
};

static int gen_create_tgt(struct nvm_dev *dev, struct nvm_ioctl_create *create)
{
        struct gen_dev *gn = dev->mp;
        struct nvm_ioctl_create_simple *s = &create->conf.s;
        struct request_queue *tqueue;
        struct gendisk *tdisk;
        struct nvm_tgt_type *tt;
        struct nvm_target *t;
        void *targetdata;

        tt = nvm_find_target_type(create->tgttype, 1);
        if (!tt) {
                pr_err("nvm: target type %s not found\n", create->tgttype);
                return -EINVAL;
        }

        mutex_lock(&gn->lock);
        t = gen_find_target(gn, create->tgtname);
        if (t) {
                pr_err("nvm: target name already exists.\n");
                mutex_unlock(&gn->lock);
                return -EINVAL;
        }
        mutex_unlock(&gn->lock);

        t = kmalloc(sizeof(struct nvm_target), GFP_KERNEL);
        if (!t)
                return -ENOMEM;

        tqueue = blk_alloc_queue_node(GFP_KERNEL, dev->q->node);
        if (!tqueue)
                goto err_t;
        blk_queue_make_request(tqueue, tt->make_rq);

        tdisk = alloc_disk(0);
        if (!tdisk)
                goto err_queue;

        sprintf(tdisk->disk_name, "%s", create->tgtname);
        tdisk->flags = GENHD_FL_EXT_DEVT;
        tdisk->major = 0;
        tdisk->first_minor = 0;
        tdisk->fops = &gen_fops;
        tdisk->queue = tqueue;

        targetdata = tt->init(dev, tdisk, s->lun_begin, s->lun_end);
        if (IS_ERR(targetdata))
                goto err_init;

        tdisk->private_data = targetdata;
        tqueue->queuedata = targetdata;

        blk_queue_max_hw_sectors(tqueue, 8 * dev->ops->max_phys_sect);

        set_capacity(tdisk, tt->capacity(targetdata));
        add_disk(tdisk);

        t->type = tt;
        t->disk = tdisk;
        t->dev = dev;

        mutex_lock(&gn->lock);
        list_add_tail(&t->list, &gn->targets);
        mutex_unlock(&gn->lock);

        return 0;
err_init:
        put_disk(tdisk);
err_queue:
        blk_cleanup_queue(tqueue);
err_t:
        kfree(t);
        return -ENOMEM;
}

static void __gen_remove_target(struct nvm_target *t)
{
        struct nvm_tgt_type *tt = t->type;
        struct gendisk *tdisk = t->disk;
        struct request_queue *q = tdisk->queue;

        del_gendisk(tdisk);
        blk_cleanup_queue(q);

        if (tt->exit)
                tt->exit(tdisk->private_data);

        put_disk(tdisk);

        list_del(&t->list);
        kfree(t);
}

/**
 * gen_remove_tgt - Removes a target from the media manager
 * @dev:        device
 * @remove:     ioctl structure with target name to remove.
 *
 * Returns:
 * 0: on success
 * 1: on not found
 * <0: on error
 */
static int gen_remove_tgt(struct nvm_dev *dev, struct nvm_ioctl_remove *remove)
{
        struct gen_dev *gn = dev->mp;
        struct nvm_target *t;

        if (!gn)
                return 1;

        mutex_lock(&gn->lock);
        t = gen_find_target(gn, remove->tgtname);
        if (!t) {
                mutex_unlock(&gn->lock);
                return 1;
        }
        __gen_remove_target(t);
        mutex_unlock(&gn->lock);

        return 0;
}

static int gen_get_area(struct nvm_dev *dev, sector_t *lba, sector_t len)
{
        struct gen_dev *gn = dev->mp;
        struct gen_area *area, *prev, *next;
        sector_t begin = 0;
        sector_t max_sectors = (dev->sec_size * dev->total_secs) >> 9;

        if (len > max_sectors)
                return -EINVAL;

        area = kmalloc(sizeof(struct gen_area), GFP_KERNEL);
        if (!area)
                return -ENOMEM;

        prev = NULL;

        spin_lock(&dev->lock);
        list_for_each_entry(next, &gn->area_list, list) {
                if (begin + len > next->begin) {
                        begin = next->end;
                        prev = next;
                        continue;
                }
                break;
        }

        if ((begin + len) > max_sectors) {
                spin_unlock(&dev->lock);
                kfree(area);
                return -EINVAL;
        }

        area->begin = *lba = begin;
        area->end = begin + len;

        if (prev) /* insert into sorted order */
                list_add(&area->list, &prev->list);
        else
                list_add(&area->list, &gn->area_list);
        spin_unlock(&dev->lock);

        return 0;
}

static void gen_put_area(struct nvm_dev *dev, sector_t begin)
{
        struct gen_dev *gn = dev->mp;
        struct gen_area *area;

        spin_lock(&dev->lock);
        list_for_each_entry(area, &gn->area_list, list) {
                if (area->begin != begin)
                        continue;

                list_del(&area->list);
                spin_unlock(&dev->lock);
                kfree(area);
                return;
        }
        spin_unlock(&dev->lock);
}

static void gen_blocks_free(struct nvm_dev *dev)
{
        struct gen_dev *gn = dev->mp;
        struct gen_lun *lun;
        int i;

        gen_for_each_lun(gn, lun, i) {
                if (!lun->vlun.blocks)
                        break;
                vfree(lun->vlun.blocks);
        }
}

static void gen_luns_free(struct nvm_dev *dev)
{
        struct gen_dev *gn = dev->mp;

        kfree(gn->luns);
}

static int gen_luns_init(struct nvm_dev *dev, struct gen_dev *gn)
{
        struct gen_lun *lun;
        int i;

        gn->luns = kcalloc(dev->nr_luns, sizeof(struct gen_lun), GFP_KERNEL);
        if (!gn->luns)
                return -ENOMEM;

        gen_for_each_lun(gn, lun, i) {
                spin_lock_init(&lun->vlun.lock);
                INIT_LIST_HEAD(&lun->free_list);
                INIT_LIST_HEAD(&lun->used_list);
                INIT_LIST_HEAD(&lun->bb_list);

                lun->reserved_blocks = 2; /* for GC only */
                lun->vlun.id = i;
                lun->vlun.lun_id = i % dev->luns_per_chnl;
                lun->vlun.chnl_id = i / dev->luns_per_chnl;
                lun->vlun.nr_free_blocks = dev->blks_per_lun;
        }
        return 0;
}

static int gen_block_bb(struct gen_dev *gn, struct ppa_addr ppa,
                                                        u8 *blks, int nr_blks)
{
        struct nvm_dev *dev = gn->dev;
        struct gen_lun *lun;
        struct nvm_block *blk;
        int i;

        nr_blks = nvm_bb_tbl_fold(dev, blks, nr_blks);
        if (nr_blks < 0)
                return nr_blks;

        lun = &gn->luns[(dev->luns_per_chnl * ppa.g.ch) + ppa.g.lun];

        for (i = 0; i < nr_blks; i++) {
                if (blks[i] == 0)
                        continue;

                blk = &lun->vlun.blocks[i];
                list_move_tail(&blk->list, &lun->bb_list);
                lun->vlun.nr_free_blocks--;
        }

        return 0;
}

static int gen_block_map(u64 slba, u32 nlb, __le64 *entries, void *private)
{
        struct nvm_dev *dev = private;
        struct gen_dev *gn = dev->mp;
        u64 elba = slba + nlb;
        struct gen_lun *lun;
        struct nvm_block *blk;
        u64 i;
        int lun_id;

        if (unlikely(elba > dev->total_secs)) {
                pr_err("gen: L2P data from device is out of bounds!\n");
                return -EINVAL;
        }

        for (i = 0; i < nlb; i++) {
                u64 pba = le64_to_cpu(entries[i]);

                if (unlikely(pba >= dev->total_secs && pba != U64_MAX)) {
                        pr_err("gen: L2P data entry is out of bounds!\n");
                        return -EINVAL;
                }

                /* Address zero is a special one. The first page on a disk is
                 * protected. It often holds internal device boot
                 * information.
                 */
                if (!pba)
                        continue;

                /* resolve block from physical address */
                lun_id = div_u64(pba, dev->sec_per_lun);
                lun = &gn->luns[lun_id];

                /* Calculate block offset into lun */
                pba = pba - (dev->sec_per_lun * lun_id);
                blk = &lun->vlun.blocks[div_u64(pba, dev->sec_per_blk)];

                if (!blk->state) {
                        /* at this point, we don't know anything about the
                         * block. It's up to the FTL on top to re-etablish the
                         * block state. The block is assumed to be open.
                         */
                        list_move_tail(&blk->list, &lun->used_list);
                        blk->state = NVM_BLK_ST_TGT;
                        lun->vlun.nr_free_blocks--;
                }
        }

        return 0;
}

static int gen_blocks_init(struct nvm_dev *dev, struct gen_dev *gn)
{
        struct gen_lun *lun;
        struct nvm_block *block;
        sector_t lun_iter, blk_iter, cur_block_id = 0;
        int ret, nr_blks;
        u8 *blks;

        nr_blks = dev->blks_per_lun * dev->plane_mode;
        blks = kmalloc(nr_blks, GFP_KERNEL);
        if (!blks)
                return -ENOMEM;

        gen_for_each_lun(gn, lun, lun_iter) {
                lun->vlun.blocks = vzalloc(sizeof(struct nvm_block) *
                                                        dev->blks_per_lun);
                if (!lun->vlun.blocks) {
                        kfree(blks);
                        return -ENOMEM;
                }

                for (blk_iter = 0; blk_iter < dev->blks_per_lun; blk_iter++) {
                        block = &lun->vlun.blocks[blk_iter];

                        INIT_LIST_HEAD(&block->list);

                        block->lun = &lun->vlun;
                        block->id = cur_block_id++;

                        /* First block is reserved for device */
                        if (unlikely(lun_iter == 0 && blk_iter == 0)) {
                                lun->vlun.nr_free_blocks--;
                                continue;
                        }

                        list_add_tail(&block->list, &lun->free_list);
                }

                if (dev->ops->get_bb_tbl) {
                        struct ppa_addr ppa;

                        ppa.ppa = 0;
                        ppa.g.ch = lun->vlun.chnl_id;
                        ppa.g.lun = lun->vlun.lun_id;

                        ret = nvm_get_bb_tbl(dev, ppa, blks);
                        if (ret)
                                pr_err("gen: could not get BB table\n");

                        ret = gen_block_bb(gn, ppa, blks, nr_blks);
                        if (ret)
                                pr_err("gen: BB table map failed\n");
                }
        }

        if ((dev->identity.dom & NVM_RSP_L2P) && dev->ops->get_l2p_tbl) {
                ret = dev->ops->get_l2p_tbl(dev, 0, dev->total_secs,
                                                        gen_block_map, dev);
                if (ret) {
                        pr_err("gen: could not read L2P table.\n");
                        pr_warn("gen: default block initialization");
                }
        }

        kfree(blks);
        return 0;
}

static void gen_free(struct nvm_dev *dev)
{
        gen_blocks_free(dev);
        gen_luns_free(dev);
        kfree(dev->mp);
        dev->mp = NULL;
}

static int gen_register(struct nvm_dev *dev)
{
        struct gen_dev *gn;
        int ret;

        if (!try_module_get(THIS_MODULE))
                return -ENODEV;

        gn = kzalloc(sizeof(struct gen_dev), GFP_KERNEL);
        if (!gn)
                return -ENOMEM;

        gn->dev = dev;
        gn->nr_luns = dev->nr_luns;
        INIT_LIST_HEAD(&gn->area_list);
        mutex_init(&gn->lock);
        INIT_LIST_HEAD(&gn->targets);
        dev->mp = gn;

        ret = gen_luns_init(dev, gn);
        if (ret) {
                pr_err("gen: could not initialize luns\n");
                goto err;
        }

        ret = gen_blocks_init(dev, gn);
        if (ret) {
                pr_err("gen: could not initialize blocks\n");
                goto err;
        }

        return 1;
err:
        gen_free(dev);
        module_put(THIS_MODULE);
        return ret;
}

static void gen_unregister(struct nvm_dev *dev)
{
        struct gen_dev *gn = dev->mp;
        struct nvm_target *t, *tmp;

        mutex_lock(&gn->lock);
        list_for_each_entry_safe(t, tmp, &gn->targets, list) {
                if (t->dev != dev)
                        continue;
                __gen_remove_target(t);
        }
        mutex_unlock(&gn->lock);

        gen_free(dev);
        module_put(THIS_MODULE);
}

static struct nvm_block *gen_get_blk(struct nvm_dev *dev,
                                struct nvm_lun *vlun, unsigned long flags)
{
        struct gen_lun *lun = container_of(vlun, struct gen_lun, vlun);
        struct nvm_block *blk = NULL;
        int is_gc = flags & NVM_IOTYPE_GC;

        spin_lock(&vlun->lock);
        if (list_empty(&lun->free_list)) {
                pr_err_ratelimited("gen: lun %u have no free pages available",
                                                                lun->vlun.id);
                goto out;
        }

        if (!is_gc && lun->vlun.nr_free_blocks < lun->reserved_blocks)
                goto out;

        blk = list_first_entry(&lun->free_list, struct nvm_block, list);

        list_move_tail(&blk->list, &lun->used_list);
        blk->state = NVM_BLK_ST_TGT;
        lun->vlun.nr_free_blocks--;
out:
        spin_unlock(&vlun->lock);
        return blk;
}

static void gen_put_blk(struct nvm_dev *dev, struct nvm_block *blk)
{
        struct nvm_lun *vlun = blk->lun;
        struct gen_lun *lun = container_of(vlun, struct gen_lun, vlun);

        spin_lock(&vlun->lock);
        if (blk->state & NVM_BLK_ST_TGT) {
                list_move_tail(&blk->list, &lun->free_list);
                lun->vlun.nr_free_blocks++;
                blk->state = NVM_BLK_ST_FREE;
        } else if (blk->state & NVM_BLK_ST_BAD) {
                list_move_tail(&blk->list, &lun->bb_list);
                blk->state = NVM_BLK_ST_BAD;
        } else {
                WARN_ON_ONCE(1);
                pr_err("gen: erroneous block type (%lu -> %u)\n",
                                                        blk->id, blk->state);
                list_move_tail(&blk->list, &lun->bb_list);
        }
        spin_unlock(&vlun->lock);
}

static void gen_mark_blk(struct nvm_dev *dev, struct ppa_addr ppa, int type)
{
        struct gen_dev *gn = dev->mp;
        struct gen_lun *lun;
        struct nvm_block *blk;

        pr_debug("gen: ppa  (ch: %u lun: %u blk: %u pg: %u) -> %u\n",
                        ppa.g.ch, ppa.g.lun, ppa.g.blk, ppa.g.pg, type);

        if (unlikely(ppa.g.ch > dev->nr_chnls ||
                                        ppa.g.lun > dev->luns_per_chnl ||
                                        ppa.g.blk > dev->blks_per_lun)) {
                WARN_ON_ONCE(1);
                pr_err("gen: ppa broken (ch: %u > %u lun: %u > %u blk: %u > %u",
                                ppa.g.ch, dev->nr_chnls,
                                ppa.g.lun, dev->luns_per_chnl,
                                ppa.g.blk, dev->blks_per_lun);
                return;
        }

        lun = &gn->luns[(dev->luns_per_chnl * ppa.g.ch) + ppa.g.lun];
        blk = &lun->vlun.blocks[ppa.g.blk];

        /* will be moved to bb list on put_blk from target */
        blk->state = type;
}

/*
 * mark block bad in gen. It is expected that the target recovers separately
 */
static void gen_mark_blk_bad(struct nvm_dev *dev, struct nvm_rq *rqd)
{
        int bit = -1;
        int max_secs = dev->ops->max_phys_sect;
        void *comp_bits = &rqd->ppa_status;

        nvm_addr_to_generic_mode(dev, rqd);

        /* look up blocks and mark them as bad */
        if (rqd->nr_ppas == 1) {
                gen_mark_blk(dev, rqd->ppa_addr, NVM_BLK_ST_BAD);
                return;
        }

        while ((bit = find_next_bit(comp_bits, max_secs, bit + 1)) < max_secs)
                gen_mark_blk(dev, rqd->ppa_list[bit], NVM_BLK_ST_BAD);
}

static void gen_end_io(struct nvm_rq *rqd)
{
        struct nvm_tgt_instance *ins = rqd->ins;

        if (rqd->error == NVM_RSP_ERR_FAILWRITE)
                gen_mark_blk_bad(rqd->dev, rqd);

        ins->tt->end_io(rqd);
}

static int gen_submit_io(struct nvm_dev *dev, struct nvm_rq *rqd)
{
        if (!dev->ops->submit_io)
                return -ENODEV;

        /* Convert address space */
        nvm_generic_to_addr_mode(dev, rqd);

        rqd->dev = dev;
        rqd->end_io = gen_end_io;
        return dev->ops->submit_io(dev, rqd);
}

static int gen_erase_blk(struct nvm_dev *dev, struct nvm_block *blk,
                                                        unsigned long flags)
{
        struct ppa_addr addr = block_to_ppa(dev, blk);

        return nvm_erase_ppa(dev, &addr, 1);
}

static int gen_reserve_lun(struct nvm_dev *dev, int lunid)
{
        return test_and_set_bit(lunid, dev->lun_map);
}

static void gen_release_lun(struct nvm_dev *dev, int lunid)
{
        WARN_ON(!test_and_clear_bit(lunid, dev->lun_map));
}

static struct nvm_lun *gen_get_lun(struct nvm_dev *dev, int lunid)
{
        struct gen_dev *gn = dev->mp;

        if (unlikely(lunid >= dev->nr_luns))
                return NULL;

        return &gn->luns[lunid].vlun;
}

static void gen_lun_info_print(struct nvm_dev *dev)
{
        struct gen_dev *gn = dev->mp;
        struct gen_lun *lun;
        unsigned int i;


        gen_for_each_lun(gn, lun, i) {
                spin_lock(&lun->vlun.lock);

                pr_info("%s: lun%8u\t%u\n", dev->name, i,
                                                lun->vlun.nr_free_blocks);

                spin_unlock(&lun->vlun.lock);
        }
}

static struct nvmm_type gen = {
        .name                   = "gennvm",
        .version                = {0, 1, 0},

        .register_mgr           = gen_register,
        .unregister_mgr         = gen_unregister,

        .create_tgt             = gen_create_tgt,
        .remove_tgt             = gen_remove_tgt,

        .get_blk                = gen_get_blk,
        .put_blk                = gen_put_blk,

        .submit_io              = gen_submit_io,
        .erase_blk              = gen_erase_blk,

        .mark_blk               = gen_mark_blk,

        .get_lun                = gen_get_lun,
        .reserve_lun            = gen_reserve_lun,
        .release_lun            = gen_release_lun,
        .lun_info_print         = gen_lun_info_print,

        .get_area               = gen_get_area,
        .put_area               = gen_put_area,

};

static int __init gen_module_init(void)
{
        return nvm_register_mgr(&gen);
}

static void gen_module_exit(void)
{
        nvm_unregister_mgr(&gen);
}

module_init(gen_module_init);
module_exit(gen_module_exit);
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("General media manager for Open-Channel SSDs");