hosts.h

基于组件方式开发操作系统的OSKIT源代码

    /*
     * 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 if this driver uses the new error handling code.  This flag is
     * really only temporary until all of the other drivers get converted
     * to use the new error handling code.
     */
    unsigned use_new_eh_code:1;

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

} 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;
    /*
     * List of commands that have been rejected because either the host
     * or the device was busy.  These need to be retried relatively quickly,
     * but we need to hold onto it for a short period until the host/device
     * is available.
     */
    Scsi_Cmnd             * pending_commands;

    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. */
    struct wait_queue     * 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;

    /*
     * Pointer to a circularly linked list - this indicates the hosts
     * that should be locked out of performing I/O while we have an active
     * command on this host.
     */
    struct Scsi_Host * block;
    unsigned wish_block:1;

    /* These parameters should be set by the detect routine */
    unsigned char *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.
     */

    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 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;
    
    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))));
};

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.
 */

/*
 * We use these goofy things because the MM is not set up when we init
 * the scsi subsystem.	By using these functions we can write code that
 * looks normal.  Also, it makes it possible to use the same code for a
 * loadable module.
 */

extern void * scsi_init_malloc(unsigned int size, int priority);
extern void scsi_init_free(char * ptr, unsigned int size);

extern int next_scsi_host;

extern int scsi_loadable_module_flag;
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_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 char major;
    unsigned char nr_dev;	  /* Number currently attached */
    unsigned char dev_noticed;	  /* Number of devices detected. */
    unsigned char 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 *);
};

extern struct Scsi_Device_Template sd_template;
extern struct Scsi_Device_Template st_template;
extern struct Scsi_Device_Template sr_template;
extern struct Scsi_Device_Template sg_template;

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
 */
#ifdef CONFIG_SCSI_PLUTO_MODULE
#define SD_EXTRA_DEVS 40
#else
#define SD_EXTRA_DEVS 4
#endif
#define ST_EXTRA_DEVS 2
#define SR_EXTRA_DEVS 2
#define SG_EXTRA_DEVS (SD_EXTRA_DEVS + SR_EXTRA_DEVS + ST_EXTRA_DEVS)

#endif
/*
 * Overrides for Emacs so that we follow Linus's tabbing style.
 * Emacs will notice this stuff at the end of the file and automatically
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