/*

   * SCSI RDMA Protocol lib functions

   *
   * Copyright (C) 2006 FUJITA Tomonori <tomof@acm.org>
   *
   * 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., 51 Franklin St, Fifth Floor, Boston, MA
   * 02110-1301 USA
   */
  #include <linux/err.h>

  #include <linux/slab.h>

  #include <linux/kfifo.h>
  #include <linux/scatterlist.h>
  #include <linux/dma-mapping.h>

  #include <scsi/scsi.h>
  #include <scsi/scsi_cmnd.h>
  #include <scsi/scsi_tcq.h>
  #include <scsi/scsi_tgt.h>
  #include <scsi/srp.h>
  #include <scsi/libsrp.h>
  
  enum srp_task_attributes {
  	SRP_SIMPLE_TASK = 0,
  	SRP_HEAD_TASK = 1,
  	SRP_ORDERED_TASK = 2,
  	SRP_ACA_TASK = 4
  };
  
  /* tmp - will replace with SCSI logging stuff */
  #define eprintk(fmt, args...)					\
  do {								\

  	printk("%s(%d) " fmt, __func__, __LINE__, ##args);	\

  } while (0)
  /* #define dprintk eprintk */
  #define dprintk(fmt, args...)
  
  static int srp_iu_pool_alloc(struct srp_queue *q, size_t max,
  			     struct srp_buf **ring)
  {
  	int i;
  	struct iu_entry *iue;
  
  	q->pool = kcalloc(max, sizeof(struct iu_entry *), GFP_KERNEL);
  	if (!q->pool)
  		return -ENOMEM;
  	q->items = kcalloc(max, sizeof(struct iu_entry), GFP_KERNEL);
  	if (!q->items)
  		goto free_pool;
  
  	spin_lock_init(&q->lock);

  	kfifo_init(&q->queue, (void *) q->pool, max * sizeof(void *));

  
  	for (i = 0, iue = q->items; i < max; i++) {

  		kfifo_in(&q->queue, (void *) &iue, sizeof(void *));

  		iue->sbuf = ring[i];
  		iue++;
  	}
  	return 0;

  	kfree(q->items);
  free_pool:
  	kfree(q->pool);
  	return -ENOMEM;
  }
  
  static void srp_iu_pool_free(struct srp_queue *q)
  {
  	kfree(q->items);
  	kfree(q->pool);
  }
  
  static struct srp_buf **srp_ring_alloc(struct device *dev,
  				       size_t max, size_t size)
  {
  	int i;
  	struct srp_buf **ring;
  
  	ring = kcalloc(max, sizeof(struct srp_buf *), GFP_KERNEL);
  	if (!ring)
  		return NULL;
  
  	for (i = 0; i < max; i++) {
  		ring[i] = kzalloc(sizeof(struct srp_buf), GFP_KERNEL);
  		if (!ring[i])
  			goto out;
  		ring[i]->buf = dma_alloc_coherent(dev, size, &ring[i]->dma,
  						  GFP_KERNEL);
  		if (!ring[i]->buf)
  			goto out;
  	}
  	return ring;
  
  out:
  	for (i = 0; i < max && ring[i]; i++) {
  		if (ring[i]->buf)
  			dma_free_coherent(dev, size, ring[i]->buf, ring[i]->dma);
  		kfree(ring[i]);
  	}
  	kfree(ring);
  
  	return NULL;
  }
  
  static void srp_ring_free(struct device *dev, struct srp_buf **ring, size_t max,
  			  size_t size)
  {
  	int i;
  
  	for (i = 0; i < max; i++) {
  		dma_free_coherent(dev, size, ring[i]->buf, ring[i]->dma);
  		kfree(ring[i]);
  	}

  	kfree(ring);

  }
  
  int srp_target_alloc(struct srp_target *target, struct device *dev,
  		     size_t nr, size_t iu_size)
  {
  	int err;
  
  	spin_lock_init(&target->lock);
  	INIT_LIST_HEAD(&target->cmd_queue);
  
  	target->dev = dev;

  	dev_set_drvdata(target->dev, target);

  
  	target->srp_iu_size = iu_size;
  	target->rx_ring_size = nr;
  	target->rx_ring = srp_ring_alloc(target->dev, nr, iu_size);
  	if (!target->rx_ring)
  		return -ENOMEM;
  	err = srp_iu_pool_alloc(&target->iu_queue, nr, target->rx_ring);
  	if (err)
  		goto free_ring;
  
  	return 0;
  
  free_ring:
  	srp_ring_free(target->dev, target->rx_ring, nr, iu_size);
  	return -ENOMEM;
  }
  EXPORT_SYMBOL_GPL(srp_target_alloc);
  
  void srp_target_free(struct srp_target *target)
  {
  	srp_ring_free(target->dev, target->rx_ring, target->rx_ring_size,
  		      target->srp_iu_size);
  	srp_iu_pool_free(&target->iu_queue);
  }
  EXPORT_SYMBOL_GPL(srp_target_free);
  
  struct iu_entry *srp_iu_get(struct srp_target *target)
  {
  	struct iu_entry *iue = NULL;

  	if (kfifo_out_locked(&target->iu_queue.queue, (void *) &iue,
  		sizeof(void *), &target->iu_queue.lock) != sizeof(void *)) {
  			WARN_ONCE(1, "unexpected fifo state");
  			return NULL;
  	}

  	if (!iue)
  		return iue;
  	iue->target = target;
  	INIT_LIST_HEAD(&iue->ilist);
  	iue->flags = 0;
  	return iue;
  }
  EXPORT_SYMBOL_GPL(srp_iu_get);
  
  void srp_iu_put(struct iu_entry *iue)
  {

  	kfifo_in_locked(&iue->target->iu_queue.queue, (void *) &iue,

  			sizeof(void *), &iue->target->iu_queue.lock);

  }
  EXPORT_SYMBOL_GPL(srp_iu_put);
  
  static int srp_direct_data(struct scsi_cmnd *sc, struct srp_direct_buf *md,
  			   enum dma_data_direction dir, srp_rdma_t rdma_io,
  			   int dma_map, int ext_desc)
  {
  	struct iu_entry *iue = NULL;
  	struct scatterlist *sg = NULL;
  	int err, nsg = 0, len;
  
  	if (dma_map) {
  		iue = (struct iu_entry *) sc->SCp.ptr;

  		sg = scsi_sglist(sc);

  		dprintk("%p %u %u %d
  ", iue, scsi_bufflen(sc),
  			md->len, scsi_sg_count(sc));

  		nsg = dma_map_sg(iue->target->dev, sg, scsi_sg_count(sc),

  				 DMA_BIDIRECTIONAL);
  		if (!nsg) {

  			printk("fail to map %p %d
  ", iue, scsi_sg_count(sc));

  			return 0;
  		}

  		len = min(scsi_bufflen(sc), md->len);

  	} else
  		len = md->len;
  
  	err = rdma_io(sc, sg, nsg, md, 1, dir, len);
  
  	if (dma_map)
  		dma_unmap_sg(iue->target->dev, sg, nsg, DMA_BIDIRECTIONAL);
  
  	return err;
  }
  
  static int srp_indirect_data(struct scsi_cmnd *sc, struct srp_cmd *cmd,
  			     struct srp_indirect_buf *id,
  			     enum dma_data_direction dir, srp_rdma_t rdma_io,
  			     int dma_map, int ext_desc)
  {
  	struct iu_entry *iue = NULL;
  	struct srp_direct_buf *md = NULL;
  	struct scatterlist dummy, *sg = NULL;
  	dma_addr_t token = 0;

  	int err = 0;

  	int nmd, nsg = 0, len;
  
  	if (dma_map || ext_desc) {
  		iue = (struct iu_entry *) sc->SCp.ptr;

  		sg = scsi_sglist(sc);

  
  		dprintk("%p %u %u %d %d
  ",

  			iue, scsi_bufflen(sc), id->len,

  			cmd->data_in_desc_cnt, cmd->data_out_desc_cnt);
  	}
  
  	nmd = id->table_desc.len / sizeof(struct srp_direct_buf);
  
  	if ((dir == DMA_FROM_DEVICE && nmd == cmd->data_in_desc_cnt) ||
  	    (dir == DMA_TO_DEVICE && nmd == cmd->data_out_desc_cnt)) {
  		md = &id->desc_list[0];
  		goto rdma;
  	}
  
  	if (ext_desc && dma_map) {
  		md = dma_alloc_coherent(iue->target->dev, id->table_desc.len,
  				&token, GFP_KERNEL);
  		if (!md) {
  			eprintk("Can't get dma memory %u
  ", id->table_desc.len);
  			return -ENOMEM;
  		}
  
  		sg_init_one(&dummy, md, id->table_desc.len);
  		sg_dma_address(&dummy) = token;

  		sg_dma_len(&dummy) = id->table_desc.len;

  		err = rdma_io(sc, &dummy, 1, &id->table_desc, 1, DMA_TO_DEVICE,
  			      id->table_desc.len);

  		if (err) {
  			eprintk("Error copying indirect table %d
  ", err);

  			goto free_mem;
  		}
  	} else {
  		eprintk("This command uses external indirect buffer
  ");
  		return -EINVAL;
  	}
  
  rdma:
  	if (dma_map) {

  		nsg = dma_map_sg(iue->target->dev, sg, scsi_sg_count(sc),
  				 DMA_BIDIRECTIONAL);

  		if (!nsg) {

  			eprintk("fail to map %p %d
  ", iue, scsi_sg_count(sc));

  			err = -EIO;

  			goto free_mem;
  		}

  		len = min(scsi_bufflen(sc), id->len);

  	} else
  		len = id->len;
  
  	err = rdma_io(sc, sg, nsg, md, nmd, dir, len);
  
  	if (dma_map)
  		dma_unmap_sg(iue->target->dev, sg, nsg, DMA_BIDIRECTIONAL);
  
  free_mem:
  	if (token && dma_map)
  		dma_free_coherent(iue->target->dev, id->table_desc.len, md, token);

  	return err;

  }
  
  static int data_out_desc_size(struct srp_cmd *cmd)
  {
  	int size = 0;
  	u8 fmt = cmd->buf_fmt >> 4;
  
  	switch (fmt) {
  	case SRP_NO_DATA_DESC:
  		break;
  	case SRP_DATA_DESC_DIRECT:
  		size = sizeof(struct srp_direct_buf);
  		break;
  	case SRP_DATA_DESC_INDIRECT:
  		size = sizeof(struct srp_indirect_buf) +
  			sizeof(struct srp_direct_buf) * cmd->data_out_desc_cnt;
  		break;
  	default:
  		eprintk("client error. Invalid data_out_format %x
  ", fmt);
  		break;
  	}
  	return size;
  }
  
  /*
   * TODO: this can be called multiple times for a single command if it
   * has very long data.
   */
  int srp_transfer_data(struct scsi_cmnd *sc, struct srp_cmd *cmd,
  		      srp_rdma_t rdma_io, int dma_map, int ext_desc)
  {
  	struct srp_direct_buf *md;
  	struct srp_indirect_buf *id;
  	enum dma_data_direction dir;
  	int offset, err = 0;
  	u8 format;

  	offset = cmd->add_cdb_len & ~3;

  
  	dir = srp_cmd_direction(cmd);
  	if (dir == DMA_FROM_DEVICE)
  		offset += data_out_desc_size(cmd);
  
  	if (dir == DMA_TO_DEVICE)
  		format = cmd->buf_fmt >> 4;
  	else
  		format = cmd->buf_fmt & ((1U << 4) - 1);
  
  	switch (format) {
  	case SRP_NO_DATA_DESC:
  		break;
  	case SRP_DATA_DESC_DIRECT:
  		md = (struct srp_direct_buf *)
  			(cmd->add_data + offset);
  		err = srp_direct_data(sc, md, dir, rdma_io, dma_map, ext_desc);
  		break;
  	case SRP_DATA_DESC_INDIRECT:
  		id = (struct srp_indirect_buf *)
  			(cmd->add_data + offset);
  		err = srp_indirect_data(sc, cmd, id, dir, rdma_io, dma_map,
  					ext_desc);
  		break;
  	default:
  		eprintk("Unknown format %d %x
  ", dir, format);

  		err = -EINVAL;

  	}
  
  	return err;
  }
  EXPORT_SYMBOL_GPL(srp_transfer_data);
  
  static int vscsis_data_length(struct srp_cmd *cmd, enum dma_data_direction dir)
  {
  	struct srp_direct_buf *md;
  	struct srp_indirect_buf *id;

  	int len = 0, offset = cmd->add_cdb_len & ~3;

  	u8 fmt;
  
  	if (dir == DMA_TO_DEVICE)
  		fmt = cmd->buf_fmt >> 4;
  	else {
  		fmt = cmd->buf_fmt & ((1U << 4) - 1);
  		offset += data_out_desc_size(cmd);
  	}
  
  	switch (fmt) {
  	case SRP_NO_DATA_DESC:
  		break;
  	case SRP_DATA_DESC_DIRECT:
  		md = (struct srp_direct_buf *) (cmd->add_data + offset);
  		len = md->len;
  		break;
  	case SRP_DATA_DESC_INDIRECT:
  		id = (struct srp_indirect_buf *) (cmd->add_data + offset);
  		len = id->len;
  		break;
  	default:
  		eprintk("invalid data format %x
  ", fmt);
  		break;
  	}
  	return len;
  }
  
  int srp_cmd_queue(struct Scsi_Host *shost, struct srp_cmd *cmd, void *info,

  		  u64 itn_id, u64 addr)

  {
  	enum dma_data_direction dir;
  	struct scsi_cmnd *sc;
  	int tag, len, err;
  
  	switch (cmd->task_attr) {
  	case SRP_SIMPLE_TASK:
  		tag = MSG_SIMPLE_TAG;
  		break;
  	case SRP_ORDERED_TASK:
  		tag = MSG_ORDERED_TAG;
  		break;
  	case SRP_HEAD_TASK:
  		tag = MSG_HEAD_TAG;
  		break;
  	default:
  		eprintk("Task attribute %d not supported
  ", cmd->task_attr);
  		tag = MSG_ORDERED_TAG;
  	}
  
  	dir = srp_cmd_direction(cmd);
  	len = vscsis_data_length(cmd, dir);
  
  	dprintk("%p %x %lx %d %d %d %llx
  ", info, cmd->cdb[0],
  		cmd->lun, dir, len, tag, (unsigned long long) cmd->tag);
  
  	sc = scsi_host_get_command(shost, dir, GFP_KERNEL);
  	if (!sc)
  		return -ENOMEM;
  
  	sc->SCp.ptr = info;
  	memcpy(sc->cmnd, cmd->cdb, MAX_COMMAND_SIZE);

  	sc->sdb.length = len;
  	sc->sdb.table.sgl = (void *) (unsigned long) addr;

  	sc->tag = tag;

  	err = scsi_tgt_queue_command(sc, itn_id, (struct scsi_lun *)&cmd->lun,
  				     cmd->tag);

  	if (err)
  		scsi_host_put_command(shost, sc);
  
  	return err;
  }
  EXPORT_SYMBOL_GPL(srp_cmd_queue);

  MODULE_DESCRIPTION("SCSI RDMA Protocol lib functions");

  MODULE_AUTHOR("FUJITA Tomonori");
  MODULE_LICENSE("GPL");