/*
 * 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 generic nvm manager for Open-Channel SSDs.
 */

#include "gennvm.h"

static int gennvm_get_area(struct nvm_dev *dev, sector_t *lba, sector_t len)
{
        struct gen_nvm *gn = dev->mp;
        struct gennvm_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 gennvm_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 gennvm_put_area(struct nvm_dev *dev, sector_t begin)
{
        struct gen_nvm *gn = dev->mp;
        struct gennvm_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 gennvm_blocks_free(struct nvm_dev *dev)
{
        struct gen_nvm *gn = dev->mp;
        struct gen_lun *lun;
        int i;

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

static void gennvm_luns_free(struct nvm_dev *dev)
{
        struct gen_nvm *gn = dev->mp;

        kfree(gn->luns);
}

static int gennvm_luns_init(struct nvm_dev *dev, struct gen_nvm *gn)
{
        struct gen_lun *lun;
        int i;

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

        gennvm_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;
                lun->vlun.nr_open_blocks = 0;
                lun->vlun.nr_closed_blocks = 0;
                lun->vlun.nr_bad_blocks = 0;
        }
        return 0;
}

static int gennvm_block_bb(struct gen_nvm *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_bad_blocks++;
                lun->vlun.nr_free_blocks--;
        }

        return 0;
}

static int gennvm_block_map(u64 slba, u32 nlb, __le64 *entries, void *private)
{
        struct nvm_dev *dev = private;
        struct gen_nvm *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("gennvm: 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("gennvm: 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_OPEN;
                        lun->vlun.nr_free_blocks--;
                        lun->vlun.nr_open_blocks++;
                }
        }

        return 0;
}

static int gennvm_blocks_init(struct nvm_dev *dev, struct gen_nvm *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;

        gennvm_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("gennvm: could not get BB table\n");

                        ret = gennvm_block_bb(gn, ppa, blks, nr_blks);
                        if (ret)
                                pr_err("gennvm: 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,
                                                        gennvm_block_map, dev);
                if (ret) {
                        pr_err("gennvm: could not read L2P table.\n");
                        pr_warn("gennvm: default block initialization");
                }
        }

        kfree(blks);
        return 0;
}

static void gennvm_free(struct nvm_dev *dev)
{
        gennvm_blocks_free(dev);
        gennvm_luns_free(dev);
        kfree(dev->mp);
        dev->mp = NULL;
}

static int gennvm_register(struct nvm_dev *dev)
{
        struct gen_nvm *gn;
        int ret;

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

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

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

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

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

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

static void gennvm_unregister(struct nvm_dev *dev)
{
        gennvm_free(dev);
        module_put(THIS_MODULE);
}

static struct nvm_block *gennvm_get_blk_unlocked(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;

        assert_spin_locked(&vlun->lock);

        if (list_empty(&lun->free_list)) {
                pr_err_ratelimited("gennvm: 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_OPEN;

        lun->vlun.nr_free_blocks--;
        lun->vlun.nr_open_blocks++;

out:
        return blk;
}

static struct nvm_block *gennvm_get_blk(struct nvm_dev *dev,
                                struct nvm_lun *vlun, unsigned long flags)
{
        struct nvm_block *blk;

        spin_lock(&vlun->lock);
        blk = gennvm_get_blk_unlocked(dev, vlun, flags);
        spin_unlock(&vlun->lock);
        return blk;
}

static void gennvm_put_blk_unlocked(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);

        assert_spin_locked(&vlun->lock);

        if (blk->state & NVM_BLK_ST_OPEN) {
                list_move_tail(&blk->list, &lun->free_list);
                lun->vlun.nr_open_blocks--;
                lun->vlun.nr_free_blocks++;
                blk->state = NVM_BLK_ST_FREE;
        } else if (blk->state & NVM_BLK_ST_CLOSED) {
                list_move_tail(&blk->list, &lun->free_list);
                lun->vlun.nr_closed_blocks--;
                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);
                lun->vlun.nr_bad_blocks++;
                blk->state = NVM_BLK_ST_BAD;
        } else {
                WARN_ON_ONCE(1);
                pr_err("gennvm: erroneous block type (%lu -> %u)\n",
                                                        blk->id, blk->state);
                list_move_tail(&blk->list, &lun->bb_list);
                lun->vlun.nr_bad_blocks++;
                blk->state = NVM_BLK_ST_BAD;
        }
}

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

        spin_lock(&vlun->lock);
        gennvm_put_blk_unlocked(dev, blk);
        spin_unlock(&vlun->lock);
}

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

        pr_debug("gennvm: 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("gennvm: 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[ppa.g.lun * ppa.g.ch];
        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 gennvm. It is expected that the target recovers separately
 */
static void gennvm_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) {
                gennvm_mark_blk(dev, rqd->ppa_addr, NVM_BLK_ST_BAD);
                return;
        }

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

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

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

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

static int gennvm_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 = gennvm_end_io;
        return dev->ops->submit_io(dev, rqd);
}

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

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

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

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

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

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


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

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

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

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

        .register_mgr           = gennvm_register,
        .unregister_mgr         = gennvm_unregister,

        .get_blk_unlocked       = gennvm_get_blk_unlocked,
        .put_blk_unlocked       = gennvm_put_blk_unlocked,

        .get_blk                = gennvm_get_blk,
        .put_blk                = gennvm_put_blk,

        .submit_io              = gennvm_submit_io,
        .erase_blk              = gennvm_erase_blk,

        .mark_blk               = gennvm_mark_blk,

        .get_lun                = gennvm_get_lun,
        .reserve_lun            = gennvm_reserve_lun,
        .release_lun            = gennvm_release_lun,
        .lun_info_print         = gennvm_lun_info_print,

        .get_area               = gennvm_get_area,
        .put_area               = gennvm_put_area,

};

static int __init gennvm_module_init(void)
{
        return nvm_register_mgr(&gennvm);
}

static void gennvm_module_exit(void)
{
        nvm_unregister_mgr(&gennvm);
}

module_init(gennvm_module_init);
module_exit(gennvm_module_exit);
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Generic media manager for Open-Channel SSDs");