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

  		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!
  ");

  			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
  ");

  			ret = gen_block_bb(gn, ppa, blks, nr_blks);

  			if (ret)

  				pr_err("gen: BB table map failed
  ");

  		}
  	}

  	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.
  ");
  			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
  ");

  		goto err;
  	}

  	ret = gen_blocks_init(dev, gn);

  	if (ret) {

  		pr_err("gen: could not initialize blocks
  ");

  		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)
  ",

  							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
  ",

  			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
  ", 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");