hosts.h

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     * True for emulated SCSI host adapters (e.g. ATAPI)
     */
    unsigned emulated:1;

    /*
     * Name of proc directory
     */
    char *proc_name;

} Scsi_Host_Template;

/*
 * The scsi_hosts array is the array containing the data for all
 * possible <supported> scsi hosts.   This is similar to the
 * Scsi_Host_Template, except that we have one entry for each
 * actual physical host adapter on the system, stored as a linked
 * list.  Note that if there are 2 aha1542 boards, then there will
 * be two Scsi_Host entries, but only 1 Scsi_Host_Template entry.
 */

struct Scsi_Host
{
/* private: */
    /*
     * This information is private to the scsi mid-layer.  Wrapping it in a
     * struct private is a way of marking it in a sort of C++ type of way.
     */
    struct Scsi_Host      * next;
    Scsi_Device           * host_queue;


    struct task_struct    * ehandler;  /* Error recovery thread. */
    struct semaphore      * eh_wait;   /* The error recovery thread waits on
                                          this. */
    struct semaphore      * eh_notify; /* wait for eh to begin */
    struct semaphore      * eh_action; /* Wait for specific actions on the
                                          host. */
    unsigned int            eh_active:1; /* Indicates the eh thread is awake and active if
                                          this is true. */
    wait_queue_head_t       host_wait;
    Scsi_Host_Template    * hostt;
    atomic_t                host_active; /* commands checked out */
    volatile unsigned short host_busy;   /* commands actually active on low-level */
    volatile unsigned short host_failed; /* commands that failed. */
    
/* public: */
    unsigned short extra_bytes;
    unsigned short 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;

    /* These parameters should be set by the detect routine */
    unsigned long base;
    unsigned long io_port;
    unsigned char n_io_port;
    unsigned char dma_channel;
    unsigned int  irq;

    /*
     * 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 rest can be copied from the template, or specifically
     * initialized, as required.
     */

    /*
     * The maximum length of SCSI commands that this host can accept.
     * Probably 12 for most host adapters, but could be 16 for others.
     * For drivers that don't set this field, a value of 12 is
     * assumed.  I am leaving this as a number rather than a bit
     * because you never know what subsequent SCSI standards might do
     * (i.e. could there be a 20 byte or a 24-byte command a few years
     * down the road?).  
     */
    unsigned char max_cmd_len;

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

    unsigned in_recovery:1;
    unsigned unchecked_isa_dma:1;
    unsigned use_clustering:1;
    /*
     * True if this host was loaded as a loadable module
     */
    unsigned loaded_as_module:1;

    /*
     * Host has rejected a command because it was busy.
     */
    unsigned host_blocked: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;

    /*
     * Indicates that one or more devices on this host were starved, and
     * when the device becomes less busy that we need to feed them.
     */
    unsigned some_device_starved:1;
   
    void (*select_queue_depths)(struct Scsi_Host *, Scsi_Device *);

    /*
     * 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))));
};

/*
 * 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(Scsi_Device * SDpnt);
extern Scsi_Device * scsi_get_host_dev(struct Scsi_Host * SHpnt);

extern void scsi_unblock_requests(struct Scsi_Host * SHpnt);
extern void scsi_block_requests(struct Scsi_Host * SHpnt);
extern void scsi_report_bus_reset(struct Scsi_Host * SHpnt, int channel);

typedef struct SHN
    {
    struct SHN * next;
    char * name;
    unsigned short host_no;
    unsigned short host_registered;
    unsigned loaded_as_module;
    } Scsi_Host_Name;
	
extern Scsi_Host_Name * scsi_host_no_list;
extern struct Scsi_Host * scsi_hostlist;
extern struct Scsi_Device_Template * scsi_devicelist;

extern Scsi_Host_Template * scsi_hosts;

extern void build_proc_dir_entries(Scsi_Host_Template  *);

/*
 *  scsi_init initializes the scsi hosts.
 */

extern int next_scsi_host;

unsigned int scsi_init(void);
extern struct Scsi_Host * scsi_register(Scsi_Host_Template *, int j);
extern void scsi_unregister(struct Scsi_Host * i);

extern void scsi_register_blocked_host(struct Scsi_Host * SHpnt);
extern void scsi_deregister_blocked_host(struct Scsi_Host * SHpnt);

/*
 * Prototypes for functions/data in scsi_scan.c
 */
extern void scan_scsis(struct Scsi_Host *shpnt,
		       uint hardcoded,
		       uint hchannel,
		       uint hid,
                       uint hlun);

extern void scsi_mark_host_reset(struct Scsi_Host *Host);

#define BLANK_HOST {"", 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}

struct Scsi_Device_Template
{
    struct Scsi_Device_Template * next;
    const char * name;
    const char * tag;
    struct module * module;	  /* Used for loadable modules */
    unsigned char scsi_type;
    unsigned int major;
    unsigned int min_major;      /* Minimum major in range. */ 
    unsigned int max_major;      /* Maximum major in range. */
    unsigned int nr_dev;	  /* Number currently attached */
    unsigned int dev_noticed;	  /* Number of devices detected. */
    unsigned int dev_max;	  /* Current size of arrays */
    unsigned blk:1;		  /* 0 if character device */
    int (*detect)(Scsi_Device *); /* Returns 1 if we can attach this device */
    int (*init)(void);		  /* Sizes arrays based upon number of devices
		   *  detected */
    void (*finish)(void);	  /* Perform initialization after attachment */
    int (*attach)(Scsi_Device *); /* Attach devices to arrays */
    void (*detach)(Scsi_Device *);
    int (*init_command)(Scsi_Cmnd *);     /* Used by new queueing code. 
                                           Selects command for blkdevs */
};

void  scsi_initialize_queue(Scsi_Device * SDpnt, struct Scsi_Host * SHpnt);

int scsi_register_device(struct Scsi_Device_Template * sdpnt);

/* These are used by loadable modules */
extern int scsi_register_module(int, void *);
extern void scsi_unregister_module(int, void *);

/* The different types of modules that we can load and unload */
#define MODULE_SCSI_HA 1
#define MODULE_SCSI_CONST 2
#define MODULE_SCSI_IOCTL 3
#define MODULE_SCSI_DEV 4


/*
 * This is an ugly hack.  If we expect to be able to load devices at run time,
 * we need to leave extra room in some of the data structures.	Doing a
 * realloc to enlarge the structures would be riddled with race conditions,
 * so until a better solution is discovered, we use this crude approach
 *
 * Even bigger hack for SparcSTORAGE arrays. Those are at least 6 disks, but
 * usually up to 30 disks, so everyone would need to change this. -jj
 *
 * Note: These things are all evil and all need to go away.  My plan is to
 * tackle the character devices first, as there aren't any locking implications
 * in the block device layer.   The block devices will require more work.
 *
 * The generics driver has been updated to resize as required.  So as the tape
 * driver. Two down, two more to go.
 */
#ifndef CONFIG_SD_EXTRA_DEVS
#define CONFIG_SD_EXTRA_DEVS 2
#endif
#ifndef CONFIG_SR_EXTRA_DEVS
#define CONFIG_SR_EXTRA_DEVS 2
#endif
#define SD_EXTRA_DEVS CONFIG_SD_EXTRA_DEVS
#define SR_EXTRA_DEVS CONFIG_SR_EXTRA_DEVS

#endif
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