/*
   *  hosts.c Copyright (C) 1992 Drew Eckhardt
   *          Copyright (C) 1993, 1994, 1995 Eric Youngdale
   *          Copyright (C) 2002-2003 Christoph Hellwig
   *
   *  mid to lowlevel SCSI driver interface
   *      Initial versions: Drew Eckhardt
   *      Subsequent revisions: Eric Youngdale
   *
   *  <drew@colorado.edu>
   *
   *  Jiffies wrap fixes (host->resetting), 3 Dec 1998 Andrea Arcangeli
   *  Added QLOGIC QLA1280 SCSI controller kernel host support. 
   *     August 4, 1999 Fred Lewis, Intel DuPont
   *
   *  Updated to reflect the new initialization scheme for the higher 
   *  level of scsi drivers (sd/sr/st)
   *  September 17, 2000 Torben Mathiasen <tmm@image.dk>
   *
   *  Restructured scsi_host lists and associated functions.
   *  September 04, 2002 Mike Anderson (andmike@us.ibm.com)
   */
  
  #include <linux/module.h>
  #include <linux/blkdev.h>
  #include <linux/kernel.h>

  #include <linux/slab.h>

  #include <linux/kthread.h>

  #include <linux/string.h>
  #include <linux/mm.h>
  #include <linux/init.h>
  #include <linux/completion.h>
  #include <linux/transport_class.h>

  #include <linux/platform_device.h>

  #include <linux/pm_runtime.h>

  
  #include <scsi/scsi_device.h>
  #include <scsi/scsi_host.h>
  #include <scsi/scsi_transport.h>
  
  #include "scsi_priv.h"
  #include "scsi_logging.h"

  static atomic_t scsi_host_next_hn;	/* host_no for next new host */

  static void scsi_host_cls_release(struct device *dev)

  {

  	put_device(&class_to_shost(dev)->shost_gendev);

  }
  
  static struct class shost_class = {
  	.name		= "scsi_host",

  	.dev_release	= scsi_host_cls_release,

  };
  
  /**

   *	scsi_host_set_state - Take the given host through the host state model.

   *	@shost:	scsi host to change the state of.
   *	@state:	state to change to.
   *
   *	Returns zero if unsuccessful or an error if the requested
   *	transition is illegal.
   **/
  int scsi_host_set_state(struct Scsi_Host *shost, enum scsi_host_state state)
  {
  	enum scsi_host_state oldstate = shost->shost_state;
  
  	if (state == oldstate)
  		return 0;
  
  	switch (state) {
  	case SHOST_CREATED:
  		/* There are no legal states that come back to
  		 * created.  This is the manually initialised start
  		 * state */
  		goto illegal;
  
  	case SHOST_RUNNING:
  		switch (oldstate) {
  		case SHOST_CREATED:
  		case SHOST_RECOVERY:
  			break;
  		default:
  			goto illegal;
  		}
  		break;
  
  	case SHOST_RECOVERY:
  		switch (oldstate) {
  		case SHOST_RUNNING:
  			break;
  		default:
  			goto illegal;
  		}
  		break;
  
  	case SHOST_CANCEL:
  		switch (oldstate) {
  		case SHOST_CREATED:
  		case SHOST_RUNNING:

  		case SHOST_CANCEL_RECOVERY:

  			break;
  		default:
  			goto illegal;
  		}
  		break;
  
  	case SHOST_DEL:
  		switch (oldstate) {
  		case SHOST_CANCEL:

  		case SHOST_DEL_RECOVERY:

  			break;
  		default:
  			goto illegal;
  		}
  		break;

  	case SHOST_CANCEL_RECOVERY:
  		switch (oldstate) {
  		case SHOST_CANCEL:
  		case SHOST_RECOVERY:
  			break;
  		default:
  			goto illegal;
  		}
  		break;
  
  	case SHOST_DEL_RECOVERY:
  		switch (oldstate) {
  		case SHOST_CANCEL_RECOVERY:
  			break;
  		default:
  			goto illegal;
  		}
  		break;

  	}
  	shost->shost_state = state;
  	return 0;
  
   illegal:
  	SCSI_LOG_ERROR_RECOVERY(1,

  				shost_printk(KERN_ERR, shost,
  					     "Illegal host state transition"
  					     "%s->%s
  ",
  					     scsi_host_state_name(oldstate),
  					     scsi_host_state_name(state)));

  	return -EINVAL;
  }
  EXPORT_SYMBOL(scsi_host_set_state);
  
  /**

   * scsi_remove_host - remove a scsi host
   * @shost:	a pointer to a scsi host to remove
   **/
  void scsi_remove_host(struct Scsi_Host *shost)
  {

  	unsigned long flags;

  	mutex_lock(&shost->scan_mutex);

  	spin_lock_irqsave(shost->host_lock, flags);
  	if (scsi_host_set_state(shost, SHOST_CANCEL))
  		if (scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY)) {
  			spin_unlock_irqrestore(shost->host_lock, flags);

  			mutex_unlock(&shost->scan_mutex);

  			return;
  		}
  	spin_unlock_irqrestore(shost->host_lock, flags);

  
  	scsi_autopm_get_host(shost);

  	scsi_forget_host(shost);

  	mutex_unlock(&shost->scan_mutex);

  	scsi_proc_host_rm(shost);

  	spin_lock_irqsave(shost->host_lock, flags);
  	if (scsi_host_set_state(shost, SHOST_DEL))
  		BUG_ON(scsi_host_set_state(shost, SHOST_DEL_RECOVERY));
  	spin_unlock_irqrestore(shost->host_lock, flags);

  
  	transport_unregister_device(&shost->shost_gendev);

  	device_unregister(&shost->shost_dev);

  	device_del(&shost->shost_gendev);
  }
  EXPORT_SYMBOL(scsi_remove_host);
  
  /**

   * scsi_add_host_with_dma - add a scsi host with dma device

   * @shost:	scsi host pointer to add
   * @dev:	a struct device of type scsi class

   * @dma_dev:	dma device for the host
   *
   * Note: You rarely need to worry about this unless you're in a
   * virtualised host environments, so use the simpler scsi_add_host()
   * function instead.

   *
   * Return value: 
   * 	0 on success / != 0 for error
   **/

  int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
  			   struct device *dma_dev)

  {
  	struct scsi_host_template *sht = shost->hostt;
  	int error = -EINVAL;
  
  	printk(KERN_INFO "scsi%d : %s
  ", shost->host_no,
  			sht->info ? sht->info(shost) : sht->name);
  
  	if (!shost->can_queue) {
  		printk(KERN_ERR "%s: can_queue = 0 no longer supported
  ",
  				sht->name);

  		goto fail;

  	}

  	error = scsi_setup_command_freelist(shost);
  	if (error)
  		goto fail;

  	if (!shost->shost_gendev.parent)
  		shost->shost_gendev.parent = dev ? dev : &platform_bus;

  	shost->dma_dev = dma_dev;

  
  	error = device_add(&shost->shost_gendev);
  	if (error)
  		goto out;

  	pm_runtime_set_active(&shost->shost_gendev);
  	pm_runtime_enable(&shost->shost_gendev);
  	device_enable_async_suspend(&shost->shost_gendev);

  	scsi_host_set_state(shost, SHOST_RUNNING);

  	get_device(shost->shost_gendev.parent);

  	device_enable_async_suspend(&shost->shost_dev);

  	error = device_add(&shost->shost_dev);

  	if (error)
  		goto out_del_gendev;
  
  	get_device(&shost->shost_gendev);

  	if (shost->transportt->host_size) {
  		shost->shost_data = kzalloc(shost->transportt->host_size,
  					 GFP_KERNEL);
  		if (shost->shost_data == NULL) {
  			error = -ENOMEM;

  			goto out_del_dev;

  		}
  	}

  
  	if (shost->transportt->create_work_queue) {

  		snprintf(shost->work_q_name, sizeof(shost->work_q_name),
  			 "scsi_wq_%d", shost->host_no);

  		shost->work_q = create_singlethread_workqueue(
  					shost->work_q_name);

  		if (!shost->work_q) {
  			error = -EINVAL;

  			goto out_free_shost_data;

  		}

  	}
  
  	error = scsi_sysfs_add_host(shost);
  	if (error)
  		goto out_destroy_host;
  
  	scsi_proc_host_add(shost);
  	return error;
  
   out_destroy_host:
  	if (shost->work_q)
  		destroy_workqueue(shost->work_q);
   out_free_shost_data:
  	kfree(shost->shost_data);

   out_del_dev:
  	device_del(&shost->shost_dev);

   out_del_gendev:
  	device_del(&shost->shost_gendev);
   out:

  	scsi_destroy_command_freelist(shost);
   fail:

  	return error;
  }

  EXPORT_SYMBOL(scsi_add_host_with_dma);

  
  static void scsi_host_dev_release(struct device *dev)
  {
  	struct Scsi_Host *shost = dev_to_shost(dev);
  	struct device *parent = dev->parent;

  	struct request_queue *q;

  	scsi_proc_hostdir_rm(shost->hostt);

  	if (shost->ehandler)
  		kthread_stop(shost->ehandler);

  	if (shost->work_q)
  		destroy_workqueue(shost->work_q);

  	q = shost->uspace_req_q;
  	if (q) {
  		kfree(q->queuedata);
  		q->queuedata = NULL;
  		scsi_free_queue(q);

  	}

  	scsi_destroy_command_freelist(shost);

  	if (shost->bqt)
  		blk_free_tags(shost->bqt);

  	kfree(shost->shost_data);

  	if (parent)
  		put_device(parent);
  	kfree(shost);
  }

  static struct device_type scsi_host_type = {

  	.name =		"scsi_host",
  	.release =	scsi_host_dev_release,
  };

  /**
   * scsi_host_alloc - register a scsi host adapter instance.
   * @sht:	pointer to scsi host template
   * @privsize:	extra bytes to allocate for driver
   *
   * Note:
   * 	Allocate a new Scsi_Host and perform basic initialization.
   * 	The host is not published to the scsi midlayer until scsi_add_host
   * 	is called.
   *
   * Return value:
   * 	Pointer to a new Scsi_Host
   **/
  struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
  {
  	struct Scsi_Host *shost;

  	gfp_t gfp_mask = GFP_KERNEL;

  
  	if (sht->unchecked_isa_dma && privsize)
  		gfp_mask |= __GFP_DMA;

  	shost = kzalloc(sizeof(struct Scsi_Host) + privsize, gfp_mask);

  	if (!shost)
  		return NULL;

  	shost->host_lock = &shost->default_lock;
  	spin_lock_init(shost->host_lock);

  	shost->shost_state = SHOST_CREATED;

  	INIT_LIST_HEAD(&shost->__devices);
  	INIT_LIST_HEAD(&shost->__targets);
  	INIT_LIST_HEAD(&shost->eh_cmd_q);
  	INIT_LIST_HEAD(&shost->starved_list);
  	init_waitqueue_head(&shost->host_wait);

  	mutex_init(&shost->scan_mutex);

  	/*
  	 * subtract one because we increment first then return, but we need to
  	 * know what the next host number was before increment
  	 */
  	shost->host_no = atomic_inc_return(&scsi_host_next_hn) - 1;

  	shost->dma_channel = 0xff;
  
  	/* These three are default values which can be overridden */
  	shost->max_channel = 0;
  	shost->max_id = 8;
  	shost->max_lun = 8;
  
  	/* Give each shost a default transportt */
  	shost->transportt = &blank_transport_template;
  
  	/*
  	 * All drivers right now should be able to handle 12 byte
  	 * commands.  Every so often there are requests for 16 byte
  	 * commands, but individual low-level drivers need to certify that
  	 * they actually do something sensible with such commands.
  	 */
  	shost->max_cmd_len = 12;
  	shost->hostt = sht;
  	shost->this_id = sht->this_id;
  	shost->can_queue = sht->can_queue;
  	shost->sg_tablesize = sht->sg_tablesize;

  	shost->sg_prot_tablesize = sht->sg_prot_tablesize;

  	shost->cmd_per_lun = sht->cmd_per_lun;
  	shost->unchecked_isa_dma = sht->unchecked_isa_dma;
  	shost->use_clustering = sht->use_clustering;

  	shost->ordered_tag = sht->ordered_tag;

  	if (sht->supported_mode == MODE_UNKNOWN)
  		/* means we didn't set it ... default to INITIATOR */
  		shost->active_mode = MODE_INITIATOR;
  	else
  		shost->active_mode = sht->supported_mode;

  	if (sht->max_host_blocked)
  		shost->max_host_blocked = sht->max_host_blocked;
  	else
  		shost->max_host_blocked = SCSI_DEFAULT_HOST_BLOCKED;
  
  	/*
  	 * If the driver imposes no hard sector transfer limit, start at
  	 * machine infinity initially.
  	 */
  	if (sht->max_sectors)
  		shost->max_sectors = sht->max_sectors;
  	else
  		shost->max_sectors = SCSI_DEFAULT_MAX_SECTORS;
  
  	/*
  	 * assume a 4GB boundary, if not set
  	 */
  	if (sht->dma_boundary)
  		shost->dma_boundary = sht->dma_boundary;
  	else
  		shost->dma_boundary = 0xffffffff;

  	device_initialize(&shost->shost_gendev);

  	dev_set_name(&shost->shost_gendev, "host%d", shost->host_no);

  	shost->shost_gendev.bus = &scsi_bus_type;

  	shost->shost_gendev.type = &scsi_host_type;

  	device_initialize(&shost->shost_dev);
  	shost->shost_dev.parent = &shost->shost_gendev;
  	shost->shost_dev.class = &shost_class;

  	dev_set_name(&shost->shost_dev, "host%d", shost->host_no);

  	shost->shost_dev.groups = scsi_sysfs_shost_attr_groups;

  	shost->ehandler = kthread_run(scsi_error_handler, shost,
  			"scsi_eh_%d", shost->host_no);
  	if (IS_ERR(shost->ehandler)) {

  		printk(KERN_WARNING "scsi%d: error handler thread failed to spawn, error = %ld
  ",
  			shost->host_no, PTR_ERR(shost->ehandler));

  		goto fail_kfree;

  	}

  
  	scsi_proc_hostdir_add(shost->hostt);
  	return shost;

   fail_kfree:
  	kfree(shost);
  	return NULL;
  }
  EXPORT_SYMBOL(scsi_host_alloc);
  
  struct Scsi_Host *scsi_register(struct scsi_host_template *sht, int privsize)
  {
  	struct Scsi_Host *shost = scsi_host_alloc(sht, privsize);
  
  	if (!sht->detect) {
  		printk(KERN_WARNING "scsi_register() called on new-style "
  				    "template for driver %s
  ", sht->name);
  		dump_stack();
  	}
  
  	if (shost)
  		list_add_tail(&shost->sht_legacy_list, &sht->legacy_hosts);
  	return shost;
  }
  EXPORT_SYMBOL(scsi_register);
  
  void scsi_unregister(struct Scsi_Host *shost)
  {
  	list_del(&shost->sht_legacy_list);
  	scsi_host_put(shost);
  }
  EXPORT_SYMBOL(scsi_unregister);

  static int __scsi_host_match(struct device *dev, void *data)

  {
  	struct Scsi_Host *p;
  	unsigned short *hostnum = (unsigned short *)data;

  	p = class_to_shost(dev);

  	return p->host_no == *hostnum;
  }

  /**
   * scsi_host_lookup - get a reference to a Scsi_Host by host no

   * @hostnum:	host number to locate
   *
   * Return value:
   *	A pointer to located Scsi_Host or NULL.

   *
   *	The caller must do a scsi_host_put() to drop the reference
   *	that scsi_host_get() took. The put_device() below dropped
   *	the reference from class_find_device().

   **/
  struct Scsi_Host *scsi_host_lookup(unsigned short hostnum)
  {

  	struct device *cdev;

  	struct Scsi_Host *shost = NULL;

  	cdev = class_find_device(&shost_class, NULL, &hostnum,
  				 __scsi_host_match);

  	if (cdev) {

  		shost = scsi_host_get(class_to_shost(cdev));

  		put_device(cdev);
  	}

  	return shost;
  }
  EXPORT_SYMBOL(scsi_host_lookup);
  
  /**
   * scsi_host_get - inc a Scsi_Host ref count
   * @shost:	Pointer to Scsi_Host to inc.
   **/
  struct Scsi_Host *scsi_host_get(struct Scsi_Host *shost)
  {

  	if ((shost->shost_state == SHOST_DEL) ||

  		!get_device(&shost->shost_gendev))
  		return NULL;
  	return shost;
  }
  EXPORT_SYMBOL(scsi_host_get);
  
  /**
   * scsi_host_put - dec a Scsi_Host ref count
   * @shost:	Pointer to Scsi_Host to dec.
   **/
  void scsi_host_put(struct Scsi_Host *shost)
  {
  	put_device(&shost->shost_gendev);
  }
  EXPORT_SYMBOL(scsi_host_put);
  
  int scsi_init_hosts(void)
  {
  	return class_register(&shost_class);
  }
  
  void scsi_exit_hosts(void)
  {
  	class_unregister(&shost_class);
  }
  
  int scsi_is_host_device(const struct device *dev)
  {

  	return dev->type == &scsi_host_type;

  }
  EXPORT_SYMBOL(scsi_is_host_device);
  
  /**
   * scsi_queue_work - Queue work to the Scsi_Host workqueue.
   * @shost:	Pointer to Scsi_Host.
   * @work:	Work to queue for execution.
   *
   * Return value:

   * 	1 - work queued for execution
   *	0 - work is already queued
   *	-EINVAL - work queue doesn't exist

   **/
  int scsi_queue_work(struct Scsi_Host *shost, struct work_struct *work)
  {
  	if (unlikely(!shost->work_q)) {
  		printk(KERN_ERR
  			"ERROR: Scsi host '%s' attempted to queue scsi-work, "
  			"when no workqueue created.
  ", shost->hostt->name);
  		dump_stack();
  
  		return -EINVAL;
  	}
  
  	return queue_work(shost->work_q, work);
  }
  EXPORT_SYMBOL_GPL(scsi_queue_work);
  
  /**
   * scsi_flush_work - Flush a Scsi_Host's workqueue.
   * @shost:	Pointer to Scsi_Host.
   **/
  void scsi_flush_work(struct Scsi_Host *shost)
  {
  	if (!shost->work_q) {
  		printk(KERN_ERR
  			"ERROR: Scsi host '%s' attempted to flush scsi-work, "
  			"when no workqueue created.
  ", shost->hostt->name);
  		dump_stack();
  		return;
  	}
  
  	flush_workqueue(shost->work_q);
  }
  EXPORT_SYMBOL_GPL(scsi_flush_work);