/*
  * Filename: dev.c
  *
  *
  * Authors: Joshua Morris <josh.h.morris@us.ibm.com>
  *	Philip Kelleher <pjk1939@linux.vnet.ibm.com>
  *
  * (C) Copyright 2013 IBM Corporation
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as
  * published by the Free Software Foundation; either version 2 of the
  * License, or (at your option) any later version.
  *
  * 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; if not, write to the Free Software Foundation,
  * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  */
  
  #include <linux/kernel.h>
  #include <linux/interrupt.h>
  #include <linux/module.h>
  #include <linux/pci.h>
  #include <linux/slab.h>
  
  #include <linux/hdreg.h>
  #include <linux/genhd.h>
  #include <linux/blkdev.h>
  #include <linux/bio.h>
  
  #include <linux/fs.h>
  
  #include "rsxx_priv.h"
  
  static unsigned int blkdev_minors = 64;
  module_param(blkdev_minors, uint, 0444);
  MODULE_PARM_DESC(blkdev_minors, "Number of minors(partitions)");
  
  /*
   * For now I'm making this tweakable in case any applications hit this limit.
   * If you see a "bio too big" error in the log you will need to raise this
   * value.
   */
  static unsigned int blkdev_max_hw_sectors = 1024;
  module_param(blkdev_max_hw_sectors, uint, 0444);
  MODULE_PARM_DESC(blkdev_max_hw_sectors, "Max hw sectors for a single BIO");
  
  static unsigned int enable_blkdev = 1;
  module_param(enable_blkdev , uint, 0444);
  MODULE_PARM_DESC(enable_blkdev, "Enable block device interfaces");
  
  
  struct rsxx_bio_meta {
  	struct bio	*bio;
  	atomic_t	pending_dmas;
  	atomic_t	error;
  	unsigned long	start_time;
  };
  
  static struct kmem_cache *bio_meta_pool;
  
  /*----------------- Block Device Operations -----------------*/
  static int rsxx_blkdev_ioctl(struct block_device *bdev,
  				 fmode_t mode,
  				 unsigned int cmd,
  				 unsigned long arg)
  {
  	struct rsxx_cardinfo *card = bdev->bd_disk->private_data;
  
  	switch (cmd) {
  	case RSXX_GETREG:
  		return rsxx_reg_access(card, (void __user *)arg, 1);
  	case RSXX_SETREG:
  		return rsxx_reg_access(card, (void __user *)arg, 0);
  	}
  
  	return -ENOTTY;
  }
  
  static int rsxx_getgeo(struct block_device *bdev, struct hd_geometry *geo)
  {
  	struct rsxx_cardinfo *card = bdev->bd_disk->private_data;
  	u64 blocks = card->size8 >> 9;
  
  	/*
  	 * get geometry: Fake it. I haven't found any drivers that set
  	 * geo->start, so we won't either.
  	 */
  	if (card->size8) {
  		geo->heads = 64;
  		geo->sectors = 16;
  		do_div(blocks, (geo->heads * geo->sectors));
  		geo->cylinders = blocks;
  	} else {
  		geo->heads = 0;
  		geo->sectors = 0;
  		geo->cylinders = 0;
  	}
  	return 0;
  }
  
  static const struct block_device_operations rsxx_fops = {
  	.owner		= THIS_MODULE,
  	.getgeo		= rsxx_getgeo,
  	.ioctl		= rsxx_blkdev_ioctl,
  };
  
  static void disk_stats_start(struct rsxx_cardinfo *card, struct bio *bio)
  {
  	struct hd_struct *part0 = &card->gendisk->part0;
  	int rw = bio_data_dir(bio);
  	int cpu;
  
  	cpu = part_stat_lock();
  
  	part_round_stats(cpu, part0);
  	part_inc_in_flight(part0, rw);
  
  	part_stat_unlock();
  }
  
  static void disk_stats_complete(struct rsxx_cardinfo *card,
  				struct bio *bio,
  				unsigned long start_time)
  {
  	struct hd_struct *part0 = &card->gendisk->part0;
  	unsigned long duration = jiffies - start_time;
  	int rw = bio_data_dir(bio);
  	int cpu;
  
  	cpu = part_stat_lock();
  
  	part_stat_add(cpu, part0, sectors[rw], bio_sectors(bio));
  	part_stat_inc(cpu, part0, ios[rw]);
  	part_stat_add(cpu, part0, ticks[rw], duration);
  
  	part_round_stats(cpu, part0);
  	part_dec_in_flight(part0, rw);
  
  	part_stat_unlock();
  }
  
  static void bio_dma_done_cb(struct rsxx_cardinfo *card,
  			    void *cb_data,
  			    unsigned int error)
  {
  	struct rsxx_bio_meta *meta = cb_data;
  
  	if (error)
  		atomic_set(&meta->error, 1);
  
  	if (atomic_dec_and_test(&meta->pending_dmas)) {
  		if (!card->eeh_state && card->gendisk)
  			disk_stats_complete(card, meta->bio, meta->start_time);
  
  		bio_endio(meta->bio, atomic_read(&meta->error) ? -EIO : 0);
  		kmem_cache_free(bio_meta_pool, meta);
  	}
  }
  
  static void rsxx_make_request(struct request_queue *q, struct bio *bio)
  {
  	struct rsxx_cardinfo *card = q->queuedata;
  	struct rsxx_bio_meta *bio_meta;
  	int st = -EINVAL;
  
  	might_sleep();
  
  	if (!card)
  		goto req_err;
  
  	if (bio_end_sector(bio) > get_capacity(card->gendisk))
  		goto req_err;
  
  	if (unlikely(card->halt)) {
  		st = -EFAULT;
  		goto req_err;
  	}
  
  	if (unlikely(card->dma_fault)) {
  		st = (-EFAULT);
  		goto req_err;
  	}
  
  	if (bio->bi_iter.bi_size == 0) {
  		dev_err(CARD_TO_DEV(card), "size zero BIO!
  ");
  		goto req_err;
  	}
  
  	bio_meta = kmem_cache_alloc(bio_meta_pool, GFP_KERNEL);
  	if (!bio_meta) {
  		st = -ENOMEM;
  		goto req_err;
  	}
  
  	bio_meta->bio = bio;
  	atomic_set(&bio_meta->error, 0);
  	atomic_set(&bio_meta->pending_dmas, 0);
  	bio_meta->start_time = jiffies;
  
  	if (!unlikely(card->halt))
  		disk_stats_start(card, bio);
  
  	dev_dbg(CARD_TO_DEV(card), "BIO[%c]: meta: %p addr8: x%llx size: %d
  ",
  		 bio_data_dir(bio) ? 'W' : 'R', bio_meta,
  		 (u64)bio->bi_iter.bi_sector << 9, bio->bi_iter.bi_size);
  
  	st = rsxx_dma_queue_bio(card, bio, &bio_meta->pending_dmas,
  				    bio_dma_done_cb, bio_meta);
  	if (st)
  		goto queue_err;
  
  	return;
  
  queue_err:
  	kmem_cache_free(bio_meta_pool, bio_meta);
  req_err:
  	bio_endio(bio, st);
  }
  
  /*----------------- Device Setup -------------------*/
  static bool rsxx_discard_supported(struct rsxx_cardinfo *card)
  {
  	unsigned char pci_rev;
  
  	pci_read_config_byte(card->dev, PCI_REVISION_ID, &pci_rev);
  
  	return (pci_rev >= RSXX_DISCARD_SUPPORT);
  }
  
  int rsxx_attach_dev(struct rsxx_cardinfo *card)
  {
  	mutex_lock(&card->dev_lock);
  
  	/* The block device requires the stripe size from the config. */
  	if (enable_blkdev) {
  		if (card->config_valid)
  			set_capacity(card->gendisk, card->size8 >> 9);
  		else
  			set_capacity(card->gendisk, 0);
  		add_disk(card->gendisk);
  
  		card->bdev_attached = 1;
  	}
  
  	mutex_unlock(&card->dev_lock);
  
  	return 0;
  }
  
  void rsxx_detach_dev(struct rsxx_cardinfo *card)
  {
  	mutex_lock(&card->dev_lock);
  
  	if (card->bdev_attached) {
  		del_gendisk(card->gendisk);
  		card->bdev_attached = 0;
  	}
  
  	mutex_unlock(&card->dev_lock);
  }
  
  int rsxx_setup_dev(struct rsxx_cardinfo *card)
  {
  	unsigned short blk_size;
  
  	mutex_init(&card->dev_lock);
  
  	if (!enable_blkdev)
  		return 0;
  
  	card->major = register_blkdev(0, DRIVER_NAME);
  	if (card->major < 0) {
  		dev_err(CARD_TO_DEV(card), "Failed to get major number
  ");
  		return -ENOMEM;
  	}
  
  	card->queue = blk_alloc_queue(GFP_KERNEL);
  	if (!card->queue) {
  		dev_err(CARD_TO_DEV(card), "Failed queue alloc
  ");
  		unregister_blkdev(card->major, DRIVER_NAME);
  		return -ENOMEM;
  	}
  
  	card->gendisk = alloc_disk(blkdev_minors);
  	if (!card->gendisk) {
  		dev_err(CARD_TO_DEV(card), "Failed disk alloc
  ");
  		blk_cleanup_queue(card->queue);
  		unregister_blkdev(card->major, DRIVER_NAME);
  		return -ENOMEM;
  	}
  
  	if (card->config_valid) {
  		blk_size = card->config.data.block_size;
  		blk_queue_dma_alignment(card->queue, blk_size - 1);
  		blk_queue_logical_block_size(card->queue, blk_size);
  	}
  
  	blk_queue_make_request(card->queue, rsxx_make_request);
  	blk_queue_bounce_limit(card->queue, BLK_BOUNCE_ANY);
  	blk_queue_max_hw_sectors(card->queue, blkdev_max_hw_sectors);
  	blk_queue_physical_block_size(card->queue, RSXX_HW_BLK_SIZE);
  
  	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, card->queue);
  	if (rsxx_discard_supported(card)) {
  		queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, card->queue);
  		blk_queue_max_discard_sectors(card->queue,
  						RSXX_HW_BLK_SIZE >> 9);
  		card->queue->limits.discard_granularity = RSXX_HW_BLK_SIZE;
  		card->queue->limits.discard_alignment   = RSXX_HW_BLK_SIZE;
  		card->queue->limits.discard_zeroes_data = 1;
  	}
  
  	card->queue->queuedata = card;
  
  	snprintf(card->gendisk->disk_name, sizeof(card->gendisk->disk_name),
  		 "rsxx%d", card->disk_id);
  	card->gendisk->driverfs_dev = &card->dev->dev;
  	card->gendisk->major = card->major;
  	card->gendisk->first_minor = 0;
  	card->gendisk->fops = &rsxx_fops;
  	card->gendisk->private_data = card;
  	card->gendisk->queue = card->queue;
  
  	return 0;
  }
  
  void rsxx_destroy_dev(struct rsxx_cardinfo *card)
  {
  	if (!enable_blkdev)
  		return;
  
  	put_disk(card->gendisk);
  	card->gendisk = NULL;
  
  	blk_cleanup_queue(card->queue);
  	card->queue->queuedata = NULL;
  	unregister_blkdev(card->major, DRIVER_NAME);
  }
  
  int rsxx_dev_init(void)
  {
  	bio_meta_pool = KMEM_CACHE(rsxx_bio_meta, SLAB_HWCACHE_ALIGN);
  	if (!bio_meta_pool)
  		return -ENOMEM;
  
  	return 0;
  }
  
  void rsxx_dev_cleanup(void)
  {
  	kmem_cache_destroy(bio_meta_pool);
  }