#ifndef _SCSI_SCSI_HOST_H
  #define _SCSI_SCSI_HOST_H
  
  #include <linux/device.h>
  #include <linux/list.h>
  #include <linux/types.h>
  #include <linux/workqueue.h>

  #include <linux/mutex.h>

  #include <linux/seq_file.h>

  #include <scsi/scsi.h>

  struct request_queue;

  struct block_device;

  struct completion;

  struct module;
  struct scsi_cmnd;
  struct scsi_device;

  struct scsi_target;

  struct Scsi_Host;
  struct scsi_host_cmd_pool;
  struct scsi_transport_template;

  struct blk_queue_tags;

  
  
  /*
   * The various choices mean:
   * NONE: Self evident.	Host adapter is not capable of scatter-gather.
   * ALL:	 Means that the host adapter module can do scatter-gather,
   *	 and that there is no limit to the size of the table to which

   *	 we scatter/gather data.  The value we set here is the maximum
   *	 single element sglist.  To use chained sglists, the adapter
   *	 has to set a value beyond ALL (and correctly use the chain
   *	 handling API.

   * Anything else:  Indicates the maximum number of chains that can be
   *	 used in one scatter-gather request.
   */
  #define SG_NONE 0

  #define SG_ALL	SCSI_MAX_SG_SEGMENTS

  #define MODE_UNKNOWN 0x00
  #define MODE_INITIATOR 0x01
  #define MODE_TARGET 0x02

  
  #define DISABLE_CLUSTERING 0
  #define ENABLE_CLUSTERING 1

  enum {
  	SCSI_QDEPTH_DEFAULT,	/* default requested change, e.g. from sysfs */
  	SCSI_QDEPTH_QFULL,	/* scsi-ml requested due to queue full */

  	SCSI_QDEPTH_RAMP_UP,	/* scsi-ml requested due to threshold event */

  };

  struct scsi_host_template {
  	struct module *module;
  	const char *name;
  
  	/*
  	 * Used to initialize old-style drivers.  For new-style drivers
  	 * just perform all work in your module initialization function.
  	 *
  	 * Status:  OBSOLETE
  	 */
  	int (* detect)(struct scsi_host_template *);
  
  	/*
  	 * Used as unload callback for hosts with old-style drivers.
  	 *
  	 * Status: OBSOLETE
  	 */
  	int (* release)(struct Scsi_Host *);
  
  	/*
  	 * The info function will return whatever useful information the
  	 * developer sees fit.  If not provided, then the name field will
  	 * be used instead.
  	 *
  	 * Status: OPTIONAL
  	 */
  	const char *(* info)(struct Scsi_Host *);
  
  	/*
  	 * Ioctl interface
  	 *
  	 * Status: OPTIONAL
  	 */
  	int (* ioctl)(struct scsi_device *dev, int cmd, void __user *arg);
  
  
  #ifdef CONFIG_COMPAT
  	/* 
  	 * Compat handler. Handle 32bit ABI.
  	 * When unknown ioctl is passed return -ENOIOCTLCMD.
  	 *
  	 * Status: OPTIONAL
  	 */
  	int (* compat_ioctl)(struct scsi_device *dev, int cmd, void __user *arg);
  #endif
  
  	/*
  	 * The queuecommand function is used to queue up a scsi
  	 * command block to the LLDD.  When the driver finished
  	 * processing the command the done callback is invoked.
  	 *
  	 * If queuecommand returns 0, then the HBA has accepted the
  	 * command.  The done() function must be called on the command
  	 * when the driver has finished with it. (you may call done on the
  	 * command before queuecommand returns, but in this case you
  	 * *must* return 0 from queuecommand).
  	 *
  	 * Queuecommand may also reject the command, in which case it may
  	 * not touch the command and must not call done() for it.
  	 *
  	 * There are two possible rejection returns:
  	 *
  	 *   SCSI_MLQUEUE_DEVICE_BUSY: Block this device temporarily, but
  	 *   allow commands to other devices serviced by this host.
  	 *
  	 *   SCSI_MLQUEUE_HOST_BUSY: Block all devices served by this
  	 *   host temporarily.
  	 *
           * For compatibility, any other non-zero return is treated the
           * same as SCSI_MLQUEUE_HOST_BUSY.
  	 *
  	 * NOTE: "temporarily" means either until the next command for#
  	 * this device/host completes, or a period of time determined by
  	 * I/O pressure in the system if there are no other outstanding
  	 * commands.
  	 *
  	 * STATUS: REQUIRED
  	 */

  	int (* queuecommand)(struct Scsi_Host *, struct scsi_cmnd *);

  
  	/*

  	 * The transfer functions are used to queue a scsi command to
  	 * the LLD. When the driver is finished processing the command
  	 * the done callback is invoked.
  	 *

  	 * This is called to inform the LLD to transfer

  	 * scsi_bufflen(cmd) bytes. scsi_sg_count(cmd) speciefies the

  	 * number of scatterlist entried in the command and

  	 * scsi_sglist(cmd) returns the scatterlist.

  	 *

  	 * return values: see queuecommand
  	 *
  	 * If the LLD accepts the cmd, it should set the result to an
  	 * appropriate value when completed before calling the done function.
  	 *
  	 * STATUS: REQUIRED FOR TARGET DRIVERS
  	 */
  	/* TODO: rename */
  	int (* transfer_response)(struct scsi_cmnd *,
  				  void (*done)(struct scsi_cmnd *));

  	/*

  	 * This is an error handling strategy routine.  You don't need to
  	 * define one of these if you don't want to - there is a default
  	 * routine that is present that should work in most cases.  For those
  	 * driver authors that have the inclination and ability to write their
  	 * own strategy routine, this is where it is specified.  Note - the
  	 * strategy routine is *ALWAYS* run in the context of the kernel eh
  	 * thread.  Thus you are guaranteed to *NOT* be in an interrupt
  	 * handler when you execute this, and you are also guaranteed to
  	 * *NOT* have any other commands being queued while you are in the
  	 * strategy routine. When you return from this function, operations
  	 * return to normal.
  	 *
  	 * See scsi_error.c scsi_unjam_host for additional comments about
  	 * what this function should and should not be attempting to do.
  	 *
  	 * Status: REQUIRED	(at least one of them)
  	 */

  	int (* eh_abort_handler)(struct scsi_cmnd *);
  	int (* eh_device_reset_handler)(struct scsi_cmnd *);

  	int (* eh_target_reset_handler)(struct scsi_cmnd *);

  	int (* eh_bus_reset_handler)(struct scsi_cmnd *);
  	int (* eh_host_reset_handler)(struct scsi_cmnd *);
  
  	/*

  	 * Before the mid layer attempts to scan for a new device where none
  	 * currently exists, it will call this entry in your driver.  Should
  	 * your driver need to allocate any structs or perform any other init
  	 * items in order to send commands to a currently unused target/lun
  	 * combo, then this is where you can perform those allocations.  This
  	 * is specifically so that drivers won't have to perform any kind of
  	 * "is this a new device" checks in their queuecommand routine,
  	 * thereby making the hot path a bit quicker.
  	 *
  	 * Return values: 0 on success, non-0 on failure
  	 *
  	 * Deallocation:  If we didn't find any devices at this ID, you will
  	 * get an immediate call to slave_destroy().  If we find something
  	 * here then you will get a call to slave_configure(), then the
  	 * device will be used for however long it is kept around, then when
  	 * the device is removed from the system (or * possibly at reboot
  	 * time), you will then get a call to slave_destroy().  This is
  	 * assuming you implement slave_configure and slave_destroy.
  	 * However, if you allocate memory and hang it off the device struct,
  	 * then you must implement the slave_destroy() routine at a minimum
  	 * in order to avoid leaking memory
  	 * each time a device is tore down.
  	 *
  	 * Status: OPTIONAL
  	 */
  	int (* slave_alloc)(struct scsi_device *);
  
  	/*
  	 * Once the device has responded to an INQUIRY and we know the
  	 * device is online, we call into the low level driver with the
  	 * struct scsi_device *.  If the low level device driver implements
  	 * this function, it *must* perform the task of setting the queue
  	 * depth on the device.  All other tasks are optional and depend
  	 * on what the driver supports and various implementation details.
  	 * 
  	 * Things currently recommended to be handled at this time include:
  	 *
  	 * 1.  Setting the device queue depth.  Proper setting of this is
  	 *     described in the comments for scsi_adjust_queue_depth.
  	 * 2.  Determining if the device supports the various synchronous
  	 *     negotiation protocols.  The device struct will already have
  	 *     responded to INQUIRY and the results of the standard items
  	 *     will have been shoved into the various device flag bits, eg.
  	 *     device->sdtr will be true if the device supports SDTR messages.
  	 * 3.  Allocating command structs that the device will need.
  	 * 4.  Setting the default timeout on this device (if needed).
  	 * 5.  Anything else the low level driver might want to do on a device
  	 *     specific setup basis...
  	 * 6.  Return 0 on success, non-0 on error.  The device will be marked
  	 *     as offline on error so that no access will occur.  If you return
  	 *     non-0, your slave_destroy routine will never get called for this
  	 *     device, so don't leave any loose memory hanging around, clean
  	 *     up after yourself before returning non-0
  	 *
  	 * Status: OPTIONAL
  	 */
  	int (* slave_configure)(struct scsi_device *);
  
  	/*
  	 * Immediately prior to deallocating the device and after all activity
  	 * has ceased the mid layer calls this point so that the low level
  	 * driver may completely detach itself from the scsi device and vice
  	 * versa.  The low level driver is responsible for freeing any memory
  	 * it allocated in the slave_alloc or slave_configure calls. 
  	 *
  	 * Status: OPTIONAL
  	 */
  	void (* slave_destroy)(struct scsi_device *);
  
  	/*

  	 * Before the mid layer attempts to scan for a new device attached
  	 * to a target where no target currently exists, it will call this
  	 * entry in your driver.  Should your driver need to allocate any
  	 * structs or perform any other init items in order to send commands
  	 * to a currently unused target, then this is where you can perform
  	 * those allocations.
  	 *
  	 * Return values: 0 on success, non-0 on failure
  	 *
  	 * Status: OPTIONAL
  	 */
  	int (* target_alloc)(struct scsi_target *);
  
  	/*
  	 * Immediately prior to deallocating the target structure, and
  	 * after all activity to attached scsi devices has ceased, the
  	 * midlayer calls this point so that the driver may deallocate
  	 * and terminate any references to the target.
  	 *
  	 * Status: OPTIONAL
  	 */
  	void (* target_destroy)(struct scsi_target *);
  
  	/*

  	 * If a host has the ability to discover targets on its own instead
  	 * of scanning the entire bus, it can fill in this function and
  	 * call scsi_scan_host().  This function will be called periodically
  	 * until it returns 1 with the scsi_host and the elapsed time of
  	 * the scan in jiffies.
  	 *
  	 * Status: OPTIONAL
  	 */
  	int (* scan_finished)(struct Scsi_Host *, unsigned long);
  
  	/*
  	 * If the host wants to be called before the scan starts, but
  	 * after the midlayer has set up ready for the scan, it can fill
  	 * in this function.

  	 *
  	 * Status: OPTIONAL

  	 */
  	void (* scan_start)(struct Scsi_Host *);
  
  	/*

  	 * Fill in this function to allow the queue depth of this host
  	 * to be changeable (on a per device basis).  Returns either

  	 * the current queue depth setting (may be different from what
  	 * was passed in) or an error.  An error should only be
  	 * returned if the requested depth is legal but the driver was
  	 * unable to set it.  If the requested depth is illegal, the
  	 * driver should set and return the closest legal queue depth.
  	 *

  	 * Status: OPTIONAL

  	 */

  	int (* change_queue_depth)(struct scsi_device *, int, int);

  
  	/*

  	 * Fill in this function to allow the changing of tag types

  	 * (this also allows the enabling/disabling of tag command
  	 * queueing).  An error should only be returned if something
  	 * went wrong in the driver while trying to set the tag type.
  	 * If the driver doesn't support the requested tag type, then
  	 * it should set the closest type it does support without
  	 * returning an error.  Returns the actual tag type set.

  	 *
  	 * Status: OPTIONAL

  	 */
  	int (* change_queue_type)(struct scsi_device *, int);
  
  	/*

  	 * This function determines the BIOS parameters for a given

  	 * harddisk.  These tend to be numbers that are made up by
  	 * the host adapter.  Parameters:
  	 * size, device, list (heads, sectors, cylinders)
  	 *

  	 * Status: OPTIONAL
  	 */

  	int (* bios_param)(struct scsi_device *, struct block_device *,
  			sector_t, int []);
  
  	/*

  	 * This function is called when one or more partitions on the
  	 * device reach beyond the end of the device.
  	 *
  	 * Status: OPTIONAL
  	 */
  	void (*unlock_native_capacity)(struct scsi_device *);
  
  	/*

  	 * Can be used to export driver statistics and other infos to the
  	 * world outside the kernel ie. userspace and it also provides an
  	 * interface to feed the driver with information.
  	 *
  	 * Status: OBSOLETE
  	 */

  	int (*show_info)(struct seq_file *, struct Scsi_Host *);
  	int (*write_info)(struct Scsi_Host *, char *, int);

  
  	/*

  	 * This is an optional routine that allows the transport to become
  	 * involved when a scsi io timer fires. The return value tells the
  	 * timer routine how to finish the io timeout handling:
  	 * EH_HANDLED:		I fixed the error, please complete the command
  	 * EH_RESET_TIMER:	I need more time, reset the timer and
  	 *			begin counting again
  	 * EH_NOT_HANDLED	Begin normal error recovery
  	 *
  	 * Status: OPTIONAL
  	 */

  	enum blk_eh_timer_return (*eh_timed_out)(struct scsi_cmnd *);

  	/* This is an optional routine that allows transport to initiate
  	 * LLD adapter or firmware reset using sysfs attribute.
  	 *
  	 * Return values: 0 on success, -ve value on failure.
  	 *
  	 * Status: OPTIONAL
  	 */
  
  	int (*host_reset)(struct Scsi_Host *shost, int reset_type);
  #define SCSI_ADAPTER_RESET	1
  #define SCSI_FIRMWARE_RESET	2

  	/*

  	 * Name of proc directory
  	 */

  	const char *proc_name;

  
  	/*
  	 * Used to store the procfs directory if a driver implements the

  	 * show_info method.

  	 */
  	struct proc_dir_entry *proc_dir;
  
  	/*
  	 * This determines if we will use a non-interrupt driven

  	 * or an interrupt driven scheme.  It is set to the maximum number

  	 * of simultaneous commands a given host adapter will accept.
  	 */
  	int can_queue;
  
  	/*
  	 * In many instances, especially where disconnect / reconnect are
  	 * supported, our host also has an ID on the SCSI bus.  If this is
  	 * the case, then it must be reserved.  Please set this_id to -1 if
  	 * your setup is in single initiator mode, and the host lacks an
  	 * ID.
  	 */
  	int this_id;
  
  	/*
  	 * This determines the degree to which the host adapter is capable
  	 * of scatter-gather.
  	 */
  	unsigned short sg_tablesize;

  	unsigned short sg_prot_tablesize;

  
  	/*

  	 * Set this if the host adapter has limitations beside segment count.

  	 */
  	unsigned short max_sectors;
  
  	/*

  	 * DMA scatter gather segment boundary limit. A segment crossing this

  	 * boundary will be split in two.
  	 */
  	unsigned long dma_boundary;
  
  	/*
  	 * This specifies "machine infinity" for host templates which don't
  	 * limit the transfer size.  Note this limit represents an absolute
  	 * maximum, and may be over the transfer limits allowed for

  	 * individual devices (e.g. 256 for SCSI-1).

  	 */
  #define SCSI_DEFAULT_MAX_SECTORS	1024
  
  	/*
  	 * True if this host adapter can make good use of linked commands.
  	 * This will allow more than one command to be queued to a given
  	 * unit on a given host.  Set this to the maximum number of command
  	 * blocks to be provided for each device.  Set this to 1 for one
  	 * command block per lun, 2 for two, etc.  Do not set this to 0.
  	 * You should make sure that the host adapter will do the right thing
  	 * before you try setting this above 1.
  	 */
  	short cmd_per_lun;
  
  	/*
  	 * present contains counter indicating how many boards of this
  	 * type were found when we did the scan.
  	 */
  	unsigned char present;
  
  	/*

  	 * This specifies the mode that a LLD supports.
  	 */
  	unsigned supported_mode:2;
  
  	/*

  	 * True if this host adapter uses unchecked DMA onto an ISA bus.

  	 */
  	unsigned unchecked_isa_dma:1;
  
  	/*

  	 * True if this host adapter can make good use of clustering.

  	 * I originally thought that if the tablesize was large that it
  	 * was a waste of CPU cycles to prepare a cluster list, but
  	 * it works out that the Buslogic is faster if you use a smaller
  	 * number of segments (i.e. use clustering).  I guess it is
  	 * inefficient.
  	 */
  	unsigned use_clustering:1;
  
  	/*

  	 * True for emulated SCSI host adapters (e.g. ATAPI).

  	 */
  	unsigned emulated:1;
  
  	/*
  	 * True if the low-level driver performs its own reset-settle delays.
  	 */
  	unsigned skip_settle_delay:1;
  
  	/*

  	 * True if we are using ordered write support.

  	 */

  	unsigned ordered_tag:1;
  
  	/*

  	 * Countdown for host blocking with no commands outstanding.

  	 */
  	unsigned int max_host_blocked;
  
  	/*
  	 * Default value for the blocking.  If the queue is empty,
  	 * host_blocked counts down in the request_fn until it restarts
  	 * host operations as zero is reached.  
  	 *
  	 * FIXME: This should probably be a value in the template
  	 */
  #define SCSI_DEFAULT_HOST_BLOCKED	7
  
  	/*
  	 * Pointer to the sysfs class properties for this host, NULL terminated.
  	 */

  	struct device_attribute **shost_attrs;

  
  	/*
  	 * Pointer to the SCSI device properties for this host, NULL terminated.
  	 */
  	struct device_attribute **sdev_attrs;
  
  	/*
  	 * List of hosts per template.
  	 *
  	 * This is only for use by scsi_module.c for legacy templates.
  	 * For these access to it is synchronized implicitly by
  	 * module_init/module_exit.
  	 */
  	struct list_head legacy_hosts;

  
  	/*
  	 * Vendor Identifier associated with the host
  	 *
  	 * Note: When specifying vendor_id, be sure to read the
  	 *   Vendor Type and ID formatting requirements specified in
  	 *   scsi_netlink.h
  	 */
  	u64 vendor_id;

  };
  
  /*

   * Temporary #define for host lock push down. Can be removed when all
   * drivers have been updated to take advantage of unlocked
   * queuecommand.
   *
   */
  #define DEF_SCSI_QCMD(func_name) \
  	int func_name(struct Scsi_Host *shost, struct scsi_cmnd *cmd)	\
  	{								\
  		unsigned long irq_flags;				\
  		int rc;							\
  		spin_lock_irqsave(shost->host_lock, irq_flags);		\
  		scsi_cmd_get_serial(shost, cmd);			\
  		rc = func_name##_lck (cmd, cmd->scsi_done);			\
  		spin_unlock_irqrestore(shost->host_lock, irq_flags);	\
  		return rc;						\
  	}
  
  
  /*

   * shost state: If you alter this, you also need to alter scsi_sysfs.c
   * (for the ascii descriptions) and the state model enforcer:
   * scsi_host_set_state()

   */

  enum scsi_host_state {
  	SHOST_CREATED = 1,
  	SHOST_RUNNING,

  	SHOST_CANCEL,

  	SHOST_DEL,

  	SHOST_RECOVERY,

  	SHOST_CANCEL_RECOVERY,
  	SHOST_DEL_RECOVERY,

  };
  
  struct Scsi_Host {
  	/*
  	 * __devices is protected by the host_lock, but you should
  	 * usually use scsi_device_lookup / shost_for_each_device
  	 * to access it and don't care about locking yourself.
  	 * In the rare case of beeing in irq context you can use
  	 * their __ prefixed variants with the lock held. NEVER
  	 * access this list directly from a driver.
  	 */
  	struct list_head	__devices;
  	struct list_head	__targets;
  	
  	struct scsi_host_cmd_pool *cmd_pool;
  	spinlock_t		free_list_lock;
  	struct list_head	free_list; /* backup store of cmd structs */
  	struct list_head	starved_list;
  
  	spinlock_t		default_lock;
  	spinlock_t		*host_lock;

  	struct mutex		scan_mutex;/* serialize scanning activity */

  
  	struct list_head	eh_cmd_q;
  	struct task_struct    * ehandler;  /* Error recovery thread. */

  	struct completion     * eh_action; /* Wait for specific actions on the
  					      host. */

  	wait_queue_head_t       host_wait;
  	struct scsi_host_template *hostt;
  	struct scsi_transport_template *transportt;

  
  	/*

  	 * Area to keep a shared tag map (if needed, will be
  	 * NULL if not).

  	 */
  	struct blk_queue_tag	*bqt;
  
  	/*

  	 * The following two fields are protected with host_lock;
  	 * however, eh routines can safely access during eh processing
  	 * without acquiring the lock.
  	 */
  	unsigned int host_busy;		   /* commands actually active on low-level */
  	unsigned int host_failed;	   /* commands that failed. */

  	unsigned int host_eh_scheduled;    /* EH scheduled without command */

  	unsigned int host_no;  /* Used for IOCTL_GET_IDLUN, /proc/scsi et al. */

  	int resetting; /* if set, it means that last_reset is a valid value */
  	unsigned long last_reset;
  
  	/*
  	 * These three parameters can be used to allow for wide scsi,
  	 * and for host adapters that support multiple busses
  	 * The first two should be set to 1 more than the actual max id
  	 * or lun (i.e. 8 for normal systems).
  	 */
  	unsigned int max_id;
  	unsigned int max_lun;
  	unsigned int max_channel;
  
  	/*
  	 * This is a unique identifier that must be assigned so that we
  	 * have some way of identifying each detected host adapter properly
  	 * and uniquely.  For hosts that do not support more than one card
  	 * in the system at one time, this does not need to be set.  It is
  	 * initialized to 0 in scsi_register.
  	 */
  	unsigned int unique_id;
  
  	/*
  	 * The maximum length of SCSI commands that this host can accept.
  	 * Probably 12 for most host adapters, but could be 16 for others.

  	 * or 260 if the driver supports variable length cdbs.

  	 * For drivers that don't set this field, a value of 12 is

  	 * assumed.

  	 */

  	unsigned short max_cmd_len;

  
  	int this_id;
  	int can_queue;
  	short cmd_per_lun;
  	short unsigned int sg_tablesize;

  	short unsigned int sg_prot_tablesize;

  	short unsigned int max_sectors;
  	unsigned long dma_boundary;
  	/* 
  	 * Used to assign serial numbers to the cmds.
  	 * Protected by the host lock.
  	 */

  	unsigned long cmd_serial_number;

  	unsigned active_mode:2;

  	unsigned unchecked_isa_dma:1;
  	unsigned use_clustering:1;
  	unsigned use_blk_tcq:1;
  
  	/*
  	 * Host has requested that no further requests come through for the
  	 * time being.
  	 */
  	unsigned host_self_blocked:1;
      
  	/*
  	 * Host uses correct SCSI ordering not PC ordering. The bit is
  	 * set for the minority of drivers whose authors actually read

  	 * the spec ;).

  	 */
  	unsigned reverse_ordering:1;
  
  	/*

  	 * Ordered write support

  	 */

  	unsigned ordered_tag:1;

  	/* Task mgmt function in progress */

  	unsigned tmf_in_progress:1;

  	/* Asynchronous scan in progress */
  	unsigned async_scan:1;

  	/* Don't resume host in EH */
  	unsigned eh_noresume:1;

  	/*
  	 * Optional work queue to be utilized by the transport
  	 */

  	char work_q_name[20];

  	struct workqueue_struct *work_q;
  
  	/*
  	 * Host has rejected a command because it was busy.
  	 */
  	unsigned int host_blocked;
  
  	/*
  	 * Value host_blocked counts down from
  	 */
  	unsigned int max_host_blocked;

  	/* Protection Information */
  	unsigned int prot_capabilities;
  	unsigned char prot_guard_type;

  	/*
  	 * q used for scsi_tgt msgs, async events or any other requests that
  	 * need to be processed in userspace
  	 */
  	struct request_queue *uspace_req_q;

  	/* legacy crap */
  	unsigned long base;
  	unsigned long io_port;
  	unsigned char n_io_port;
  	unsigned char dma_channel;
  	unsigned int  irq;
  	

  	enum scsi_host_state shost_state;

  
  	/* ldm bits */

  	struct device		shost_gendev, shost_dev;

  
  	/*
  	 * List of hosts per template.
  	 *
  	 * This is only for use by scsi_module.c for legacy templates.
  	 * For these access to it is synchronized implicitly by
  	 * module_init/module_exit.
  	 */
  	struct list_head sht_legacy_list;
  
  	/*
  	 * Points to the transport data (if any) which is allocated
  	 * separately
  	 */
  	void *shost_data;
  
  	/*

  	 * Points to the physical bus device we'd use to do DMA
  	 * Needed just in case we have virtual hosts.
  	 */
  	struct device *dma_dev;
  
  	/*

  	 * We should ensure that this is aligned, both for better performance
  	 * and also because some compilers (m68k) don't automatically force
  	 * alignment to a long boundary.
  	 */
  	unsigned long hostdata[0]  /* Used for storage of host specific stuff */
  		__attribute__ ((aligned (sizeof(unsigned long))));
  };
  
  #define		class_to_shost(d)	\

  	container_of(d, struct Scsi_Host, shost_dev)

  #define shost_printk(prefix, shost, fmt, a...)	\
  	dev_printk(prefix, &(shost)->shost_gendev, fmt, ##a)

  static inline void *shost_priv(struct Scsi_Host *shost)
  {
  	return (void *)shost->hostdata;
  }

  int scsi_is_host_device(const struct device *);
  
  static inline struct Scsi_Host *dev_to_shost(struct device *dev)
  {
  	while (!scsi_is_host_device(dev)) {
  		if (!dev->parent)
  			return NULL;
  		dev = dev->parent;
  	}
  	return container_of(dev, struct Scsi_Host, shost_gendev);
  }

  static inline int scsi_host_in_recovery(struct Scsi_Host *shost)
  {
  	return shost->shost_state == SHOST_RECOVERY ||
  		shost->shost_state == SHOST_CANCEL_RECOVERY ||

  		shost->shost_state == SHOST_DEL_RECOVERY ||
  		shost->tmf_in_progress;

  }

  extern int scsi_queue_work(struct Scsi_Host *, struct work_struct *);
  extern void scsi_flush_work(struct Scsi_Host *);
  
  extern struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *, int);

  extern int __must_check scsi_add_host_with_dma(struct Scsi_Host *,
  					       struct device *,
  					       struct device *);

  extern void scsi_scan_host(struct Scsi_Host *);

  extern void scsi_rescan_device(struct device *);
  extern void scsi_remove_host(struct Scsi_Host *);
  extern struct Scsi_Host *scsi_host_get(struct Scsi_Host *);
  extern void scsi_host_put(struct Scsi_Host *t);
  extern struct Scsi_Host *scsi_host_lookup(unsigned short);

  extern const char *scsi_host_state_name(enum scsi_host_state);

  extern void scsi_cmd_get_serial(struct Scsi_Host *, struct scsi_cmnd *);

  
  extern u64 scsi_calculate_bounce_limit(struct Scsi_Host *);

  static inline int __must_check scsi_add_host(struct Scsi_Host *host,
  					     struct device *dev)
  {
  	return scsi_add_host_with_dma(host, dev, dev);
  }

  static inline struct device *scsi_get_device(struct Scsi_Host *shost)
  {
          return shost->shost_gendev.parent;
  }

  /**
   * scsi_host_scan_allowed - Is scanning of this host allowed
   * @shost:	Pointer to Scsi_Host.
   **/
  static inline int scsi_host_scan_allowed(struct Scsi_Host *shost)
  {

  	return shost->shost_state == SHOST_RUNNING ||
  	       shost->shost_state == SHOST_RECOVERY;

  }

  extern void scsi_unblock_requests(struct Scsi_Host *);
  extern void scsi_block_requests(struct Scsi_Host *);
  
  struct class_container;

  
  extern struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost,
  						void (*) (struct request_queue *));

  /*
   * These two functions are used to allocate and free a pseudo device
   * which will connect to the host adapter itself rather than any
   * physical device.  You must deallocate when you are done with the
   * thing.  This physical pseudo-device isn't real and won't be available
   * from any high-level drivers.
   */
  extern void scsi_free_host_dev(struct scsi_device *);
  extern struct scsi_device *scsi_get_host_dev(struct Scsi_Host *);

  /*
   * DIF defines the exchange of protection information between
   * initiator and SBC block device.
   *
   * DIX defines the exchange of protection information between OS and
   * initiator.
   */
  enum scsi_host_prot_capabilities {
  	SHOST_DIF_TYPE1_PROTECTION = 1 << 0, /* T10 DIF Type 1 */
  	SHOST_DIF_TYPE2_PROTECTION = 1 << 1, /* T10 DIF Type 2 */
  	SHOST_DIF_TYPE3_PROTECTION = 1 << 2, /* T10 DIF Type 3 */
  
  	SHOST_DIX_TYPE0_PROTECTION = 1 << 3, /* DIX between OS and HBA only */
  	SHOST_DIX_TYPE1_PROTECTION = 1 << 4, /* DIX with DIF Type 1 */
  	SHOST_DIX_TYPE2_PROTECTION = 1 << 5, /* DIX with DIF Type 2 */
  	SHOST_DIX_TYPE3_PROTECTION = 1 << 6, /* DIX with DIF Type 3 */
  };
  
  /*
   * SCSI hosts which support the Data Integrity Extensions must
   * indicate their capabilities by setting the prot_capabilities using
   * this call.
   */
  static inline void scsi_host_set_prot(struct Scsi_Host *shost, unsigned int mask)
  {
  	shost->prot_capabilities = mask;
  }
  
  static inline unsigned int scsi_host_get_prot(struct Scsi_Host *shost)
  {
  	return shost->prot_capabilities;
  }

  static inline int scsi_host_prot_dma(struct Scsi_Host *shost)
  {
  	return shost->prot_capabilities >= SHOST_DIX_TYPE0_PROTECTION;
  }

  static inline unsigned int scsi_host_dif_capable(struct Scsi_Host *shost, unsigned int target_type)
  {

  	static unsigned char cap[] = { 0,
  				       SHOST_DIF_TYPE1_PROTECTION,
  				       SHOST_DIF_TYPE2_PROTECTION,
  				       SHOST_DIF_TYPE3_PROTECTION };

  	if (target_type >= ARRAY_SIZE(cap))

  		return 0;

  	return shost->prot_capabilities & cap[target_type] ? target_type : 0;

  }
  
  static inline unsigned int scsi_host_dix_capable(struct Scsi_Host *shost, unsigned int target_type)
  {

  #if defined(CONFIG_BLK_DEV_INTEGRITY)

  	static unsigned char cap[] = { SHOST_DIX_TYPE0_PROTECTION,
  				       SHOST_DIX_TYPE1_PROTECTION,
  				       SHOST_DIX_TYPE2_PROTECTION,
  				       SHOST_DIX_TYPE3_PROTECTION };

  	if (target_type >= ARRAY_SIZE(cap))

  		return 0;

  	return shost->prot_capabilities & cap[target_type];

  #endif

  	return 0;
  }
  
  /*
   * All DIX-capable initiators must support the T10-mandated CRC
   * checksum.  Controllers can optionally implement the IP checksum
   * scheme which has much lower impact on system performance.  Note
   * that the main rationale for the checksum is to match integrity
   * metadata with data.  Detecting bit errors are a job for ECC memory
   * and buses.
   */
  
  enum scsi_host_guard_type {
  	SHOST_DIX_GUARD_CRC = 1 << 0,
  	SHOST_DIX_GUARD_IP  = 1 << 1,
  };
  
  static inline void scsi_host_set_guard(struct Scsi_Host *shost, unsigned char type)
  {
  	shost->prot_guard_type = type;
  }
  
  static inline unsigned char scsi_host_get_guard(struct Scsi_Host *shost)
  {
  	return shost->prot_guard_type;
  }

  /* legacy interfaces */
  extern struct Scsi_Host *scsi_register(struct scsi_host_template *, int);
  extern void scsi_unregister(struct Scsi_Host *);

  extern int scsi_host_set_state(struct Scsi_Host *, enum scsi_host_state);

  
  #endif /* _SCSI_SCSI_HOST_H */