Import 2.1.81

[davej-history.git] / drivers / scsi / scsi.c

/*
 *  scsi.c Copyright (C) 1992 Drew Eckhardt
 *         Copyright (C) 1993, 1994, 1995 Eric Youngdale
 *
 *  generic mid-level SCSI driver
 *      Initial versions: Drew Eckhardt
 *      Subsequent revisions: Eric Youngdale
 *
 *  <drew@colorado.edu>
 *
 *  Bug correction thanks go to :
 *      Rik Faith <faith@cs.unc.edu>
 *      Tommy Thorn <tthorn>
 *      Thomas Wuensche <tw@fgb1.fgb.mw.tu-muenchen.de>
 *
 *  Modified by Eric Youngdale eric@andante.jic.com or ericy@gnu.ai.mit.edu to
 *  add scatter-gather, multiple outstanding request, and other
 *  enhancements.
 *
 *  Native multichannel, wide scsi, /proc/scsi and hot plugging
 *  support added by Michael Neuffer <mike@i-connect.net>
 *
 *  Added request_module("scsi_hostadapter") for kerneld:
 *  (Put an "alias scsi_hostadapter your_hostadapter" in /etc/conf.modules)
 *  Bjorn Ekwall  <bj0rn@blox.se>
 *
 *  Major improvements to the timeout, abort, and reset processing,
 *  as well as performance modifications for large queue depths by
 *  Leonard N. Zubkoff <lnz@dandelion.com>
 */

#include <linux/config.h>
#include <linux/module.h>

#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/malloc.h>
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/stat.h>
#include <linux/blk.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/init.h>

#define __KERNEL_SYSCALLS__

#include <linux/unistd.h>

#include <asm/system.h>
#include <asm/irq.h>
#include <asm/dma.h>

#include "scsi.h"
#include "hosts.h"
#include "constants.h"

#ifdef CONFIG_KERNELD
#include <linux/kerneld.h>
#endif

#undef USE_STATIC_SCSI_MEMORY

/*
static const char RCSid[] = "$Header: /vger/u4/cvs/linux/drivers/scsi/scsi.c,v 1.38 1997/01/19 23:07:18 davem Exp $";
*/

/*
 * Definitions and constants.
 */
#define INTERNAL_ERROR (panic ("Internal error in file %s, line %d.\n", __FILE__, __LINE__))

/*
 * PAGE_SIZE must be a multiple of the sector size (512).  True
 * for all reasonably recent architectures (even the VAX...).
 */
#define SECTOR_SIZE             512
#define SECTORS_PER_PAGE        (PAGE_SIZE/SECTOR_SIZE)

#if SECTORS_PER_PAGE <= 8
 typedef unsigned char  FreeSectorBitmap;
#elif SECTORS_PER_PAGE <= 32
 typedef unsigned int   FreeSectorBitmap;
#else
# error You lose.
#endif

#define MAX_SCSI_DEVICE_CODE 10

#ifdef DEBUG
    #define SCSI_TIMEOUT (5*HZ)
#else
    #define SCSI_TIMEOUT (2*HZ)
#endif

#define MIN_RESET_DELAY (2*HZ)

/* Do not call reset on error if we just did a reset within 15 sec. */
#define MIN_RESET_PERIOD (15*HZ)

/* The following devices are known not to tolerate a lun != 0 scan for
 * one reason or another.  Some will respond to all luns, others will
 * lock up.
 */

#define BLIST_NOLUN     0x01
#define BLIST_FORCELUN  0x02
#define BLIST_BORKEN    0x04
#define BLIST_KEY       0x08
#define BLIST_SINGLELUN 0x10
#define BLIST_NOTQ      0x20
#define BLIST_SPARSELUN 0x40

/*
 * Data declarations.
 */
unsigned long             scsi_pid = 0;
Scsi_Cmnd               * last_cmnd = NULL;
/* Command groups 3 and 4 are reserved and should never be used.  */
const unsigned char       scsi_command_size[8] = { 6, 10, 10, 12, 
                                                   12, 12, 10, 10 };
static unsigned long      serial_number = 0;
static Scsi_Cmnd        * scsi_bh_queue_head = NULL;
static FreeSectorBitmap * dma_malloc_freelist = NULL;
static int                need_isa_bounce_buffers;
static unsigned int       dma_sectors = 0;
unsigned int              scsi_dma_free_sectors = 0;
unsigned int              scsi_need_isa_buffer = 0;
static unsigned char   ** dma_malloc_pages = NULL;

/*
 * Note - the initial logging level can be set here to log events at boot time.
 * After the system is up, you may enable logging via the /proc interface.
 */
unsigned int              scsi_logging_level = 0;

static volatile struct Scsi_Host * host_active = NULL;

#if CONFIG_PROC_FS
/* 
 * This is the pointer to the /proc/scsi code.
 * It is only initialized to !=0 if the scsi code is present
 */
struct proc_dir_entry proc_scsi_scsi = {
    PROC_SCSI_SCSI, 4, "scsi",
    S_IFREG | S_IRUGO | S_IWUSR, 1, 0, 0, 0,
    NULL,
    NULL, NULL,
    NULL, NULL, NULL
};
#endif


const char *const scsi_device_types[MAX_SCSI_DEVICE_CODE] =
{
    "Direct-Access    ",
    "Sequential-Access",
    "Printer          ",
    "Processor        ",
    "WORM             ",
    "CD-ROM           ",
    "Scanner          ",
    "Optical Device   ",
    "Medium Changer   ",
    "Communications   "
};

/* 
 * Function prototypes.
 */
static void resize_dma_pool(void);
static void print_inquiry(unsigned char *data);
extern void scsi_times_out (Scsi_Cmnd * SCpnt);
static int  scan_scsis_single (int channel,int dev,int lun,int * max_scsi_dev ,
                 int * sparse_lun, Scsi_Device ** SDpnt, Scsi_Cmnd * SCpnt,
                 struct Scsi_Host *shpnt, char * scsi_result);
void        scsi_build_commandblocks(Scsi_Device * SDpnt);

/*
 * These are the interface to the old error handling code.  It should go away
 * someday soon.
 */
extern void scsi_old_done (Scsi_Cmnd *SCpnt);
extern void scsi_old_times_out (Scsi_Cmnd * SCpnt);

#if CONFIG_PROC_FS
extern int (* dispatch_scsi_info_ptr)(int ino, char *buffer, char **start,
                                      off_t offset, int length, int inout);
extern int dispatch_scsi_info(int ino, char *buffer, char **start,
                              off_t offset, int length, int inout);
#endif

#define SCSI_BLOCK(DEVICE, HOST)                                                \
                ((HOST->block && host_active && HOST != host_active)            \
                  || ((HOST)->can_queue && HOST->host_busy >= HOST->can_queue)    \
                  || ((HOST)->host_blocked)                                       \
                  || ((DEVICE) != NULL && (DEVICE)->device_blocked) )

static void scsi_dump_status(int level);


struct dev_info{
    const char * vendor;
    const char * model;
    const char * revision; /* Latest revision known to be bad.  Not used yet */
    unsigned flags;
};

/*
 * This is what was previously known as the blacklist.  The concept
 * has been expanded so that we can specify other types of things we
 * need to be aware of.
 */
static struct dev_info device_list[] =
{
{"CHINON","CD-ROM CDS-431","H42", BLIST_NOLUN}, /* Locks up if polled for lun != 0 */
{"CHINON","CD-ROM CDS-535","Q14", BLIST_NOLUN}, /* Locks up if polled for lun != 0 */
{"DENON","DRD-25X","V", BLIST_NOLUN},           /* Locks up if probed for lun != 0 */
{"HITACHI","DK312C","CM81", BLIST_NOLUN},       /* Responds to all lun - dtg */
{"HITACHI","DK314C","CR21" , BLIST_NOLUN},      /* responds to all lun */
{"IMS", "CDD521/10","2.06", BLIST_NOLUN},       /* Locks-up when LUN>0 polled. */
{"MAXTOR","XT-3280","PR02", BLIST_NOLUN},       /* Locks-up when LUN>0 polled. */
{"MAXTOR","XT-4380S","B3C", BLIST_NOLUN},       /* Locks-up when LUN>0 polled. */
{"MAXTOR","MXT-1240S","I1.2", BLIST_NOLUN},     /* Locks up when LUN>0 polled */
{"MAXTOR","XT-4170S","B5A", BLIST_NOLUN},       /* Locks-up sometimes when LUN>0 polled. */
{"MAXTOR","XT-8760S","B7B", BLIST_NOLUN},       /* guess what? */
{"MEDIAVIS","RENO CD-ROMX2A","2.03",BLIST_NOLUN},/*Responds to all lun */
{"MICROP", "4110", "*", BLIST_NOTQ},            /* Buggy Tagged Queuing */
{"NEC","CD-ROM DRIVE:841","1.0", BLIST_NOLUN},  /* Locks-up when LUN>0 polled. */
{"RODIME","RO3000S","2.33", BLIST_NOLUN},       /* Locks up if polled for lun != 0 */
{"SANYO", "CRD-250S", "1.20", BLIST_NOLUN},     /* causes failed REQUEST SENSE on lun 1
                                                 * for aha152x controller, which causes
                                                 * SCSI code to reset bus.*/
{"SEAGATE", "ST157N", "\004|j", BLIST_NOLUN},   /* causes failed REQUEST SENSE on lun 1
                                                 * for aha152x controller, which causes
                                                 * SCSI code to reset bus.*/
{"SEAGATE", "ST296","921", BLIST_NOLUN},        /* Responds to all lun */
{"SEAGATE","ST1581","6538",BLIST_NOLUN},        /* Responds to all lun */
{"SONY","CD-ROM CDU-541","4.3d", BLIST_NOLUN},
{"SONY","CD-ROM CDU-55S","1.0i", BLIST_NOLUN},
{"SONY","CD-ROM CDU-561","1.7x", BLIST_NOLUN},
{"TANDBERG","TDC 3600","U07", BLIST_NOLUN},     /* Locks up if polled for lun != 0 */
{"TEAC","CD-ROM","1.06", BLIST_NOLUN},          /* causes failed REQUEST SENSE on lun 1
                                                 * for seagate controller, which causes
                                                 * SCSI code to reset bus.*/
{"TEXEL","CD-ROM","1.06", BLIST_NOLUN},         /* causes failed REQUEST SENSE on lun 1
                                                 * for seagate controller, which causes
                                                 * SCSI code to reset bus.*/
{"QUANTUM","LPS525S","3110", BLIST_NOLUN},      /* Locks sometimes if polled for lun != 0 */
{"QUANTUM","PD1225S","3110", BLIST_NOLUN},      /* Locks sometimes if polled for lun != 0 */
{"MEDIAVIS","CDR-H93MV","1.31", BLIST_NOLUN},   /* Locks up if polled for lun != 0 */
{"SANKYO", "CP525","6.64", BLIST_NOLUN},        /* causes failed REQ SENSE, extra reset */
{"HP", "C1750A", "3226", BLIST_NOLUN},          /* scanjet iic */
{"HP", "C1790A", "", BLIST_NOLUN},              /* scanjet iip */
{"HP", "C2500A", "", BLIST_NOLUN},              /* scanjet iicx */
{"YAMAHA", "CDR102", "1.00", BLIST_NOLUN},      /* extra reset */

/*
 * Other types of devices that have special flags.
 */
{"SONY","CD-ROM CDU-8001","*", BLIST_BORKEN},
{"TEXEL","CD-ROM","1.06", BLIST_BORKEN},
{"IOMEGA","Io20S         *F","*", BLIST_KEY},
{"INSITE","Floptical   F*8I","*", BLIST_KEY},
{"INSITE","I325VM","*", BLIST_KEY},
{"NRC","MBR-7","*", BLIST_FORCELUN | BLIST_SINGLELUN},
{"NRC","MBR-7.4","*", BLIST_FORCELUN | BLIST_SINGLELUN},
{"NAKAMICH","MJ-4.8S","*", BLIST_FORCELUN | BLIST_SINGLELUN},
{"PIONEER","CD-ROM DRM-602X","*", BLIST_FORCELUN | BLIST_SINGLELUN},
{"PIONEER","CD-ROM DRM-604X","*", BLIST_FORCELUN | BLIST_SINGLELUN},
{"EMULEX","MD21/S2     ESDI","*", BLIST_SINGLELUN},
{"CANON","IPUBJD","*", BLIST_SPARSELUN},
{"nCipher","Fastness Crypto","*", BLIST_FORCELUN},
{"MATSHITA","PD","*", BLIST_FORCELUN | BLIST_SINGLELUN},
{"YAMAHA","CDR100","1.00", BLIST_NOLUN},        /* Locks up if polled for lun != 0 */
{"YAMAHA","CDR102","1.00", BLIST_NOLUN},        /* Locks up if polled for lun != 0 */
/*
 * Must be at end of list...
 */
{NULL, NULL, NULL}
};

static int get_device_flags(unsigned char * response_data){
    int i = 0;
    unsigned char * pnt;
    for(i=0; 1; i++){
        if(device_list[i].vendor == NULL) return 0;
        pnt = &response_data[8];
        while(*pnt && *pnt == ' ') pnt++;
        if(memcmp(device_list[i].vendor, pnt,
                  strlen(device_list[i].vendor))) continue;
        pnt = &response_data[16];
        while(*pnt && *pnt == ' ') pnt++;
        if(memcmp(device_list[i].model, pnt,
                  strlen(device_list[i].model))) continue;
        return device_list[i].flags;
    }
    return 0;
}

/*
 * Function:    scsi_make_blocked_list
 *
 * Purpose:     Build linked list of hosts that require blocking.
 *
 * Arguments:   None.
 *
 * Returns:     Nothing
 *
 * Notes:       Blocking is sort of a hack that is used to prevent more than one
 *              host adapter from being active at one time.  This is used in cases
 *              where the ISA bus becomes unreliable if you have more than one
 *              host adapter really pumping data through.
 *
 *              We spent a lot of time examining the problem, and I *believe* that
 *              the problem is bus related as opposed to being a driver bug.
 *
 *              The blocked list is used as part of the synchronization object
 *              that we use to ensure that only one host is active at one time.
 *              I (ERY) would like to make this go away someday, but this would
 *              require that we have a recursive mutex object.
 */
void 
scsi_make_blocked_list(void)  
{
    int block_count = 0, index;
    unsigned long flags;
    struct Scsi_Host * sh[128], * shpnt;

    /*
     * Create a circular linked list from the scsi hosts which have
     * the "wish_block" field in the Scsi_Host structure set.
     * The blocked list should include all the scsi hosts using ISA DMA.
     * In some systems, using two dma channels simultaneously causes
     * unpredictable results.
     * Among the scsi hosts in the blocked list, only one host at a time
     * is allowed to have active commands queued. The transition from
     * one active host to the next one is allowed only when host_busy == 0
     * for the active host (which implies host_busy == 0 for all the hosts
     * in the list). Moreover for block devices the transition to a new
     * active host is allowed only when a request is completed, since a
     * block device request can be divided into multiple scsi commands
     * (when there are few sg lists or clustering is disabled).
     *
     * (DB, 4 Feb 1995)
     */

    save_flags(flags);
    cli();
    host_active = NULL;

    for(shpnt=scsi_hostlist; shpnt; shpnt = shpnt->next) {

#if 0
        /*
         * Is this is a candidate for the blocked list?
         * Useful to put into the blocked list all the hosts whose driver
         * does not know about the host->block feature.
         */
        if (shpnt->unchecked_isa_dma) shpnt->wish_block = 1;
#endif

        if (shpnt->wish_block) sh[block_count++] = shpnt;
    }

    if (block_count == 1) sh[0]->block = NULL;

    else if (block_count > 1) {
        
        for(index = 0; index < block_count - 1; index++) {
            sh[index]->block = sh[index + 1];
            printk("scsi%d : added to blocked host list.\n",
                   sh[index]->host_no);
        }

        sh[block_count - 1]->block = sh[0];
        printk("scsi%d : added to blocked host list.\n",
               sh[index]->host_no);
    }

    restore_flags(flags);
}

static void scan_scsis_done (Scsi_Cmnd * SCpnt)
{

    SCSI_LOG_MLCOMPLETE(1,printk ("scan_scsis_done(%p, %06x)\n", SCpnt->host, SCpnt->result));
    SCpnt->request.rq_status = RQ_SCSI_DONE;

    if (SCpnt->request.sem != NULL)
        up(SCpnt->request.sem);
}

void scsi_logging_setup(char *str, int *ints) 
{
    if (ints[0] != 1) {
        printk("scsi_logging_setup : usage scsi_logging_level=n "
               "(n should be 0 or non-zero)\n");
    } else {
        scsi_logging_level = (ints[1])? ~0 : 0;
    }
}

#ifdef CONFIG_SCSI_MULTI_LUN
static int max_scsi_luns = 8;
#else
static int max_scsi_luns = 1;
#endif

void scsi_luns_setup(char *str, int *ints) 
{
    if (ints[0] != 1)
        printk("scsi_luns_setup : usage max_scsi_luns=n (n should be between 1 and 8)\n");
    else
        max_scsi_luns = ints[1];
}

/*
 *  Detecting SCSI devices :
 *  We scan all present host adapter's busses,  from ID 0 to ID (max_id).
 *  We use the INQUIRY command, determine device type, and pass the ID /
 *  lun address of all sequential devices to the tape driver, all random
 *  devices to the disk driver.
 */
static void scan_scsis (struct Scsi_Host *shpnt, 
                        unchar hardcoded,
                        unchar hchannel, 
                        unchar hid, 
                        unchar hlun)
{
  int             channel;
  int             dev;
  int             lun;
  int             max_dev_lun;
  Scsi_Cmnd     * SCpnt;
  unsigned char * scsi_result;
  unsigned char   scsi_result0[256];
  Scsi_Device   * SDpnt;
  Scsi_Device   * SDtail;
  int             sparse_lun;

  SCpnt = (Scsi_Cmnd *) scsi_init_malloc (sizeof (Scsi_Cmnd), GFP_ATOMIC | GFP_DMA);
  memset (SCpnt, 0, sizeof (Scsi_Cmnd));

  SDpnt = (Scsi_Device *) scsi_init_malloc (sizeof (Scsi_Device), GFP_ATOMIC);
  memset (SDpnt, 0, sizeof (Scsi_Device));


  /* Make sure we have something that is valid for DMA purposes */
  scsi_result = ( ( !shpnt->unchecked_isa_dma )
                 ? &scsi_result0[0] : scsi_init_malloc (512, GFP_DMA));

  if (scsi_result == NULL) 
  {
      printk ("Unable to obtain scsi_result buffer\n");
      goto leave;
  }

  /*
   * We must chain ourself in the host_queue, so commands can time out 
   */
  SCpnt->next = NULL;
  SDpnt->device_queue = SCpnt;
  SDpnt->host = shpnt;
  SDpnt->online = TRUE;

  /*
   * Next, hook the device to the host in question.
   */
  SDpnt->prev = NULL;
  SDpnt->next = NULL;
  if( shpnt->host_queue != NULL )
  {
      SDtail = shpnt->host_queue;
      while( SDtail->next != NULL )
          SDtail = SDtail->next;

      SDtail->next = SDpnt;
      SDpnt->prev = SDtail;
  }
  else
  {
      shpnt->host_queue = SDpnt;
  }

  /*
   * We need to increment the counter for this one device so we can track when
   * things are quiet.
   */
  atomic_inc(&shpnt->host_active); 

  if (hardcoded == 1) {
    Scsi_Device *oldSDpnt=SDpnt;
    struct Scsi_Device_Template * sdtpnt;
    channel = hchannel;
    if(channel > shpnt->max_channel) goto leave;
    dev = hid;
    if(dev >= shpnt->max_id) goto leave;
    lun = hlun;
    if(lun >= shpnt->max_lun) goto leave;
    scan_scsis_single (channel, dev, lun, &max_dev_lun, &sparse_lun,
                       &SDpnt, SCpnt, shpnt, scsi_result);
    if(SDpnt!=oldSDpnt) {

        /* it could happen the blockdevice hasn't yet been inited */
    for(sdtpnt = scsi_devicelist; sdtpnt; sdtpnt = sdtpnt->next)
        if(sdtpnt->init && sdtpnt->dev_noticed) (*sdtpnt->init)();

            oldSDpnt->scsi_request_fn = NULL;
            for(sdtpnt = scsi_devicelist; sdtpnt; sdtpnt = sdtpnt->next)
                if(sdtpnt->attach) {
                  (*sdtpnt->attach)(oldSDpnt);
                  if(oldSDpnt->attached) scsi_build_commandblocks(oldSDpnt);}
            resize_dma_pool();

        for(sdtpnt = scsi_devicelist; sdtpnt; sdtpnt = sdtpnt->next) {
            if(sdtpnt->finish && sdtpnt->nr_dev)
                {(*sdtpnt->finish)();}
        }
    }

  }
  else {
    for (channel = 0; channel <= shpnt->max_channel; channel++) {
      for (dev = 0; dev < shpnt->max_id; ++dev) {
        if (shpnt->this_id != dev) {

          /*
           * We need the for so our continue, etc. work fine. We put this in
           * a variable so that we can override it during the scan if we
           * detect a device *KNOWN* to have multiple logical units.
           */
          max_dev_lun = (max_scsi_luns < shpnt->max_lun ?
                         max_scsi_luns : shpnt->max_lun);
          sparse_lun = 0;
          for (lun = 0; lun < max_dev_lun; ++lun) {
            if (!scan_scsis_single (channel, dev, lun, &max_dev_lun,
                                    &sparse_lun, &SDpnt, SCpnt, shpnt,
                                    scsi_result)
                && !sparse_lun)
              break; /* break means don't probe further for luns!=0 */
          }                     /* for lun ends */
        }                       /* if this_id != id ends */
      }                         /* for dev ends */
    }                           /* for channel ends */
  }                             /* if/else hardcoded */

  /*
   * We need to decrement the counter for this one device
   * so we know when everything is quiet.
   */
  atomic_dec(&shpnt->host_active); 

  leave:

  {/* Unchain SCpnt from host_queue */
      Scsi_Device *prev, *next;
      Scsi_Device * dqptr;
      
      for(dqptr = shpnt->host_queue; dqptr != SDpnt; dqptr = dqptr->next) 
          continue;
      if(dqptr) 
      {
          prev = dqptr->prev;
          next = dqptr->next;
          if(prev)
              prev->next = next;
          else
              shpnt->host_queue = next;
          if(next) next->prev = prev;
      }
  }

     /* Last device block does not exist.  Free memory. */
    if (SDpnt != NULL)
      scsi_init_free ((char *) SDpnt, sizeof (Scsi_Device));

    if (SCpnt != NULL)
      scsi_init_free ((char *) SCpnt, sizeof (Scsi_Cmnd));

    /* If we allocated a buffer so we could do DMA, free it now */
    if (scsi_result != &scsi_result0[0] && scsi_result != NULL)
    {
        scsi_init_free (scsi_result, 512);
    }

    {
        Scsi_Device * sdev;
        Scsi_Cmnd   * scmd;

        SCSI_LOG_SCAN_BUS(4,printk("Host status for host %p:\n", shpnt));
        for(sdev = shpnt->host_queue; sdev; sdev = sdev->next)
        {
            SCSI_LOG_SCAN_BUS(4,printk("Device %d %p: ", sdev->id, sdev));
            for(scmd=sdev->device_queue; scmd; scmd = scmd->next)
            {
                SCSI_LOG_SCAN_BUS(4,printk("%p ", scmd));
            }
            SCSI_LOG_SCAN_BUS(4,printk("\n"));
        }
    }
}

/*
 * The worker for scan_scsis.
 * Returning 0 means Please don't ask further for lun!=0, 1 means OK go on.
 * Global variables used : scsi_devices(linked list)
 */
int scan_scsis_single (int channel, int dev, int lun, int *max_dev_lun,
    int *sparse_lun, Scsi_Device **SDpnt2, Scsi_Cmnd * SCpnt,
    struct Scsi_Host * shpnt, char *scsi_result)
{
  unsigned char scsi_cmd[12];
  struct Scsi_Device_Template *sdtpnt;
  Scsi_Device * SDtail, *SDpnt=*SDpnt2;
  int bflags, type=-1;

  SDpnt->host = shpnt;
  SDpnt->id = dev;
  SDpnt->lun = lun;
  SDpnt->channel = channel;
  SDpnt->online = TRUE;

  /* Some low level driver could use device->type (DB) */
  SDpnt->type = -1;

  /*
   * Assume that the device will have handshaking problems, and then fix this
   * field later if it turns out it doesn't
   */
  SDpnt->borken = 1;
  SDpnt->was_reset = 0;
  SDpnt->expecting_cc_ua = 0;

  scsi_cmd[0] = TEST_UNIT_READY;
  scsi_cmd[1] = lun << 5;
  scsi_cmd[2] = scsi_cmd[3] = scsi_cmd[4] = scsi_cmd[5] = 0;

  SCpnt->host = SDpnt->host;
  SCpnt->device = SDpnt;
  SCpnt->target = SDpnt->id;
  SCpnt->lun = SDpnt->lun;
  SCpnt->channel = SDpnt->channel;
  {
    struct semaphore sem = MUTEX_LOCKED;
    SCpnt->request.sem = &sem;
    SCpnt->request.rq_status = RQ_SCSI_BUSY;
    scsi_do_cmd (SCpnt, (void *) scsi_cmd,
                 (void *) scsi_result,
                 256, scan_scsis_done, SCSI_TIMEOUT + 4 * HZ, 5);
    down (&sem);
    SCpnt->request.sem = NULL;
  }

  SCSI_LOG_SCAN_BUS(3,  printk ("scsi: scan_scsis_single id %d lun %d. Return code 0x%08x\n",
          dev, lun, SCpnt->result));
  SCSI_LOG_SCAN_BUS(3,print_driverbyte(SCpnt->result));
  SCSI_LOG_SCAN_BUS(3,print_hostbyte(SCpnt->result));
  SCSI_LOG_SCAN_BUS(3,printk("\n"));

  if (SCpnt->result) {
    if (((driver_byte (SCpnt->result) & DRIVER_SENSE) ||
         (status_byte (SCpnt->result) & CHECK_CONDITION)) &&
        ((SCpnt->sense_buffer[0] & 0x70) >> 4) == 7) {
      if (((SCpnt->sense_buffer[2] & 0xf) != NOT_READY) &&
          ((SCpnt->sense_buffer[2] & 0xf) != UNIT_ATTENTION) &&
          ((SCpnt->sense_buffer[2] & 0xf) != ILLEGAL_REQUEST || lun > 0))
        return 1;
    }
    else
      return 0;
  }

  SCSI_LOG_SCAN_BUS(3,printk ("scsi: performing INQUIRY\n"));
  /*
   * Build an INQUIRY command block.
   */
  scsi_cmd[0] = INQUIRY;
  scsi_cmd[1] = (lun << 5) & 0xe0;
  scsi_cmd[2] = 0;
  scsi_cmd[3] = 0;
  scsi_cmd[4] = 255;
  scsi_cmd[5] = 0;
  SCpnt->cmd_len = 0;
  {
    struct semaphore sem = MUTEX_LOCKED;
    SCpnt->request.sem = &sem;
    SCpnt->request.rq_status = RQ_SCSI_BUSY;
    scsi_do_cmd (SCpnt, (void *) scsi_cmd,
                 (void *) scsi_result,
                 256, scan_scsis_done, SCSI_TIMEOUT, 3);
    down (&sem);
    SCpnt->request.sem = NULL;
  }

  SCSI_LOG_SCAN_BUS(3,printk ("scsi: INQUIRY %s with code 0x%x\n",
                              SCpnt->result ? "failed" : "successful", SCpnt->result));

  if (SCpnt->result)
    return 0;     /* assume no peripheral if any sort of error */

  /*
   * Check the peripheral qualifier field - this tells us whether LUNS
   * are supported here or not.
   */
  if( (scsi_result[0] >> 5) == 3 )
    {
      return 0;     /* assume no peripheral if any sort of error */
    }

  /*
   * It would seem some TOSHIBA CDROM gets things wrong
   */
  if (!strncmp (scsi_result + 8, "TOSHIBA", 7) &&
      !strncmp (scsi_result + 16, "CD-ROM", 6) &&
      scsi_result[0] == TYPE_DISK) {
    scsi_result[0] = TYPE_ROM;
    scsi_result[1] |= 0x80;     /* removable */
  }

  memcpy (SDpnt->vendor, scsi_result + 8, 8);
  memcpy (SDpnt->model, scsi_result + 16, 16);
  memcpy (SDpnt->rev, scsi_result + 32, 4);

  SDpnt->removable = (0x80 & scsi_result[1]) >> 7;
  SDpnt->online = TRUE;
  SDpnt->lockable = SDpnt->removable;
  SDpnt->changed = 0;
  SDpnt->access_count = 0;
  SDpnt->busy = 0;
  SDpnt->has_cmdblocks = 0;
  /*
   * Currently, all sequential devices are assumed to be tapes, all random
   * devices disk, with the appropriate read only flags set for ROM / WORM
   * treated as RO.
   */
  switch (type = (scsi_result[0] & 0x1f)) {
  case TYPE_TAPE:
  case TYPE_DISK:
  case TYPE_MOD:
  case TYPE_PROCESSOR:
  case TYPE_SCANNER:
    SDpnt->writeable = 1;
    break;
  case TYPE_WORM:
  case TYPE_ROM:
    SDpnt->writeable = 0;
    break;
  default:
    printk ("scsi: unknown type %d\n", type);
  }

  SDpnt->device_blocked = FALSE;
  SDpnt->device_busy = 0;
  SDpnt->single_lun = 0;
  SDpnt->soft_reset =
    (scsi_result[7] & 1) && ((scsi_result[3] & 7) == 2);
  SDpnt->random = (type == TYPE_TAPE) ? 0 : 1;
  SDpnt->type = (type & 0x1f);

  print_inquiry (scsi_result);

  for (sdtpnt = scsi_devicelist; sdtpnt;
       sdtpnt = sdtpnt->next)
    if (sdtpnt->detect)
      SDpnt->attached +=
        (*sdtpnt->detect) (SDpnt);

  SDpnt->scsi_level = scsi_result[2] & 0x07;
  if (SDpnt->scsi_level >= 2 ||
      (SDpnt->scsi_level == 1 &&
       (scsi_result[3] & 0x0f) == 1))
    SDpnt->scsi_level++;

  /*
   * Accommodate drivers that want to sleep when they should be in a polling
   * loop.
   */
  SDpnt->disconnect = 0;

  /*
   * Get any flags for this device.
   */
  bflags = get_device_flags (scsi_result);

  /*
   * Set the tagged_queue flag for SCSI-II devices that purport to support
   * tagged queuing in the INQUIRY data.
   */
  SDpnt->tagged_queue = 0;
  if ((SDpnt->scsi_level >= SCSI_2) &&
      (scsi_result[7] & 2) &&
      !(bflags & BLIST_NOTQ)) {
    SDpnt->tagged_supported = 1;
    SDpnt->current_tag = 0;
  }

  /*
   * Some revisions of the Texel CD ROM drives have handshaking problems when
   * used with the Seagate controllers.  Before we know what type of device
   * we're talking to, we assume it's borken and then change it here if it
   * turns out that it isn't a TEXEL drive.
   */
  if ((bflags & BLIST_BORKEN) == 0)
    SDpnt->borken = 0;

  /*
   * If we want to only allow I/O to one of the luns attached to this device
   * at a time, then we set this flag.
   */
  if (bflags & BLIST_SINGLELUN)
    SDpnt->single_lun = 1;

  /*
   * These devices need this "key" to unlock the devices so we can use it
   */
  if ((bflags & BLIST_KEY) != 0) {
    printk ("Unlocked floptical drive.\n");
    SDpnt->lockable = 0;
    scsi_cmd[0] = MODE_SENSE;
    scsi_cmd[1] = (lun << 5) & 0xe0;
    scsi_cmd[2] = 0x2e;
    scsi_cmd[3] = 0;
    scsi_cmd[4] = 0x2a;
    scsi_cmd[5] = 0;
    SCpnt->cmd_len = 0;
    {
      struct semaphore sem = MUTEX_LOCKED;
      SCpnt->request.rq_status = RQ_SCSI_BUSY;
      SCpnt->request.sem = &sem;
      scsi_do_cmd (SCpnt, (void *) scsi_cmd,
                   (void *) scsi_result, 0x2a,
                   scan_scsis_done, SCSI_TIMEOUT, 3);
      down (&sem);
      SCpnt->request.sem = NULL;
    }
  }

  /*
   * Detach the command from the device. It was just a temporary to be used while
   * scanning the bus - the real ones will be allocated later.
   */
  SDpnt->device_queue = NULL;

  /*
   * This device was already hooked up to the host in question,
   * so at this point we just let go of it and it should be fine.  We do need to
   * allocate a new one and attach it to the host so that we can further scan the bus.
   */
  SDpnt = (Scsi_Device *) scsi_init_malloc (sizeof (Scsi_Device), GFP_ATOMIC);
  *SDpnt2=SDpnt;
  if (!SDpnt)
  {
      printk ("scsi: scan_scsis_single: Cannot malloc\n");
      return 0;
  }

  memset (SDpnt, 0, sizeof (Scsi_Device));

  /*
   * And hook up our command block to the new device we will be testing
   * for.
   */
  SDpnt->device_queue = SCpnt;
  SDpnt->online = TRUE;

  /*
   * Since we just found one device, there had damn well better be one in the list
   * already.
   */
  if( shpnt->host_queue == NULL )
      panic("scan_scsis_single: Host queue == NULL\n");

  SDtail = shpnt->host_queue;
  while (SDtail->next)
  {
      SDtail = SDtail->next;
  }

  /* Add this device to the linked list at the end */
  SDtail->next = SDpnt;
  SDpnt->prev = SDtail;
  SDpnt->next = NULL;

  /*
   * Some scsi devices cannot be polled for lun != 0 due to firmware bugs
   */
  if (bflags & BLIST_NOLUN)
    return 0;                   /* break; */

  /*
   * If this device is known to support sparse multiple units, override the
   * other settings, and scan all of them.
   */
  if (bflags & BLIST_SPARSELUN) {
    *max_dev_lun = 8;
    *sparse_lun = 1;
    return 1;
  }

  /*
   * If this device is known to support multiple units, override the other
   * settings, and scan all of them.
   */
  if (bflags & BLIST_FORCELUN) {
    *max_dev_lun = 8;
    return 1;
  }
  /*
   * We assume the device can't handle lun!=0 if: - it reports scsi-0 (ANSI
   * SCSI Revision 0) (old drives like MAXTOR XT-3280) or - it reports scsi-1
   * (ANSI SCSI Revision 1) and Response Data Format 0
   */
  if (((scsi_result[2] & 0x07) == 0)
      ||
      ((scsi_result[2] & 0x07) == 1 &&
       (scsi_result[3] & 0x0f) == 0))
    return 0;
  return 1;
}

/*
 *  Flag bits for the internal_timeout array
 */
#define NORMAL_TIMEOUT 0
#define IN_ABORT  1
#define IN_RESET  2
#define IN_RESET2 4
#define IN_RESET3 8


/* This function takes a quick look at a request, and decides if it
 * can be queued now, or if there would be a stall while waiting for
 * something else to finish.  This routine assumes that interrupts are
 * turned off when entering the routine.  It is the responsibility
 * of the calling code to ensure that this is the case.
 */

Scsi_Cmnd * scsi_request_queueable (struct request * req, Scsi_Device * device)
{
    Scsi_Cmnd * SCpnt = NULL;
    int tablesize;
    Scsi_Cmnd * found = NULL;
    struct buffer_head * bh, *bhp;

    if (!device)
        panic ("No device passed to scsi_request_queueable().\n");

    if (req && req->rq_status == RQ_INACTIVE)
        panic("Inactive in scsi_request_queueable");

    /*
     * Look for a free command block.  If we have been instructed not to queue
     * multiple commands to multi-lun devices, then check to see what else is
     * going for this device first.
     */

    if (!device->single_lun) {
        SCpnt = device->device_queue;
        while(SCpnt){
            if(SCpnt->request.rq_status == RQ_INACTIVE) break;
            SCpnt = SCpnt->next;
        }
    } else {
        SCpnt = device->device_queue;
        while(SCpnt){
            if(SCpnt->channel == device->channel
                && SCpnt->target == device->id) {
                if (SCpnt->lun == device->lun) {
                    if(found == NULL
                       && SCpnt->request.rq_status == RQ_INACTIVE)
                    {
                        found=SCpnt;
                    }
                }
                if(SCpnt->request.rq_status != RQ_INACTIVE) {
                    /*
                     * I think that we should really limit things to one
                     * outstanding command per device - this is what tends
                     * to trip up buggy firmware.
                     */
                    return NULL;
                }
            }
            SCpnt = SCpnt->next;
        }
        SCpnt = found;
    }

    if (!SCpnt) return NULL;

    if (SCSI_BLOCK(device, device->host)) return NULL;

    if (req) {
        memcpy(&SCpnt->request, req, sizeof(struct request));
        tablesize = device->host->sg_tablesize;
        bhp = bh = req->bh;
        if(!tablesize) bh = NULL;
        /* Take a quick look through the table to see how big it is.
         * We already have our copy of req, so we can mess with that
         * if we want to.
         */
        while(req->nr_sectors && bh){
            bhp = bhp->b_reqnext;
            if(!bhp || !CONTIGUOUS_BUFFERS(bh,bhp)) tablesize--;
            req->nr_sectors -= bh->b_size >> 9;
            req->sector += bh->b_size >> 9;
            if(!tablesize) break;
            bh = bhp;
        }
        if(req->nr_sectors && bh && bh->b_reqnext){  /* Any leftovers? */
            SCpnt->request.bhtail = bh;
            req->bh = bh->b_reqnext; /* Divide request */
            bh->b_reqnext = NULL;
            bh = req->bh;

            /* Now reset things so that req looks OK */
            SCpnt->request.nr_sectors -= req->nr_sectors;
            req->current_nr_sectors = bh->b_size >> 9;
            req->buffer = bh->b_data;
            SCpnt->request.sem = NULL; /* Wait until whole thing done */
        } else {
            req->rq_status = RQ_INACTIVE;
            wake_up(&wait_for_request);
        }
    } else {
        SCpnt->request.rq_status = RQ_SCSI_BUSY;  /* Busy, but no request */
        SCpnt->request.sem = NULL;   /* And no one is waiting for the device
                                      * either */
    }

    atomic_inc(&SCpnt->host->host_active); 
    SCSI_LOG_MLQUEUE(5, printk("Activating command for device %d (%d)\n", SCpnt->target,
                               atomic_read(&SCpnt->host->host_active)));
    SCpnt->use_sg = 0;               /* Reset the scatter-gather flag */
    SCpnt->old_use_sg  = 0;
    SCpnt->transfersize = 0;
    SCpnt->underflow = 0;
    SCpnt->cmd_len = 0;

/* Since not everyone seems to set the device info correctly
 * before Scsi_Cmnd gets send out to scsi_do_command, we do it here.
 */
    SCpnt->channel = device->channel;
    SCpnt->lun = device->lun;
    SCpnt->target = device->id;
    SCpnt->state = SCSI_STATE_INITIALIZING;
    SCpnt->owner = SCSI_OWNER_HIGHLEVEL;

    return SCpnt;
}

/* This function returns a structure pointer that will be valid for
 * the device.  The wait parameter tells us whether we should wait for
 * the unit to become free or not.  We are also able to tell this routine
 * not to return a descriptor if the host is unable to accept any more
 * commands for the time being.  We need to keep in mind that there is no
 * guarantee that the host remain not busy.  Keep in mind the
 * scsi_request_queueable function also knows the internal allocation scheme
 * of the packets for each device
 */

Scsi_Cmnd * scsi_allocate_device (struct request ** reqp, Scsi_Device * device,
                             int wait)
{
    kdev_t dev;
    struct request * req = NULL;
    int tablesize;
    unsigned long flags;
    struct buffer_head * bh, *bhp;
    struct Scsi_Host * host;
    Scsi_Cmnd * SCpnt = NULL;
    Scsi_Cmnd * SCwait = NULL;
    Scsi_Cmnd * found = NULL;

    if (!device)
        panic ("No device passed to scsi_allocate_device().\n");

    if (reqp) req = *reqp;

    /* See if this request has already been queued by an interrupt routine */
    if (req) {
        if(req->rq_status == RQ_INACTIVE) return NULL;
        dev = req->rq_dev;
    } else
        dev = 0;                /* unused */

    host = device->host;

    if (in_interrupt() && SCSI_BLOCK(device, host)) return NULL;

    while (1==1){
        if (!device->single_lun) {
            SCpnt = device->device_queue;
            while(SCpnt){
                SCwait = SCpnt;
                if(SCpnt->request.rq_status == RQ_INACTIVE) break;
                SCpnt = SCpnt->next;
            }
        } else {
            SCpnt = device->device_queue;
            while(SCpnt){
                if(SCpnt->channel == device->channel
                   && SCpnt->target == device->id) {
                    if (SCpnt->lun == device->lun) {
                        SCwait = SCpnt;
                        if(found == NULL
                           && SCpnt->request.rq_status == RQ_INACTIVE)
                        {
                            found=SCpnt;
                        }
                    }
                    if(SCpnt->request.rq_status != RQ_INACTIVE) {
                        /*
                         * I think that we should really limit things to one
                         * outstanding command per device - this is what tends
                         * to trip up buggy firmware.
                         */
                        found = NULL;
                        break;
                    }
                }
                SCpnt = SCpnt->next;
            }
            SCpnt = found;
        }

        save_flags(flags);
        cli();
        /* See if this request has already been queued by an interrupt routine
         */
        if (req && (req->rq_status == RQ_INACTIVE || req->rq_dev != dev)) {
            restore_flags(flags);
            return NULL;
        }
        if (!SCpnt || SCpnt->request.rq_status != RQ_INACTIVE)  /* Might have changed */
        {
                if (wait && SCwait && SCwait->request.rq_status != RQ_INACTIVE){
                        sleep_on(&device->device_wait);
                        restore_flags(flags);
                } else {
                        restore_flags(flags);
                        if (!wait) return NULL;
                        if (!SCwait) {
                                printk("Attempt to allocate device channel %d,"
                                       " target %d, lun %d\n", device->channel,
                                       device->id, device->lun);
                                panic("No device found in scsi_allocate_device\n");
                        }
                }
        } else {
            if (req) {
                memcpy(&SCpnt->request, req, sizeof(struct request));
                tablesize = device->host->sg_tablesize;
                bhp = bh = req->bh;
                if(!tablesize) bh = NULL;
                /* Take a quick look through the table to see how big it is.
                 * We already have our copy of req, so we can mess with that
                 * if we want to.
                 */
                while(req->nr_sectors && bh){
                    bhp = bhp->b_reqnext;
                    if(!bhp || !CONTIGUOUS_BUFFERS(bh,bhp)) tablesize--;
                    req->nr_sectors -= bh->b_size >> 9;
                    req->sector += bh->b_size >> 9;
                    if(!tablesize) break;
                    bh = bhp;
                }
                if(req->nr_sectors && bh && bh->b_reqnext){/* Any leftovers? */
                    SCpnt->request.bhtail = bh;
                    req->bh = bh->b_reqnext; /* Divide request */
                    bh->b_reqnext = NULL;
                    bh = req->bh;
                    /* Now reset things so that req looks OK */
                    SCpnt->request.nr_sectors -= req->nr_sectors;
                    req->current_nr_sectors = bh->b_size >> 9;
                    req->buffer = bh->b_data;
                    SCpnt->request.sem = NULL; /* Wait until whole thing done*/
                }
                else
                {
                    req->rq_status = RQ_INACTIVE;
                    *reqp = req->next;
                    wake_up(&wait_for_request);
                }
            } else {
                SCpnt->request.rq_status = RQ_SCSI_BUSY;
                SCpnt->request.sem = NULL;   /* And no one is waiting for this
                                              * to complete */
            }
            atomic_inc(&SCpnt->host->host_active); 
            restore_flags(flags);
            SCSI_LOG_MLQUEUE(5, printk("Activating command for device %d (%d)\n", 
                                       SCpnt->target,
                                       atomic_read(&SCpnt->host->host_active)));
            break;
        }
    }

    SCpnt->use_sg = 0;            /* Reset the scatter-gather flag */
    SCpnt->old_use_sg  = 0;
    SCpnt->transfersize = 0;      /* No default transfer size */
    SCpnt->cmd_len = 0;

    SCpnt->underflow = 0;         /* Do not flag underflow conditions */

    /* Since not everyone seems to set the device info correctly
     * before Scsi_Cmnd gets send out to scsi_do_command, we do it here.
     * FIXME(eric) This doesn't make any sense.
     */
    SCpnt->channel = device->channel;
    SCpnt->lun = device->lun;
    SCpnt->target = device->id;
    SCpnt->state = SCSI_STATE_INITIALIZING;
    SCpnt->owner = SCSI_OWNER_HIGHLEVEL;

    return SCpnt;
}

/*
 * Function:    scsi_release_command
 *
 * Purpose:     Release a command block.
 *
 * Arguments:   SCpnt - command block we are releasing.
 *
 * Notes:       The command block can no longer be used by the caller once
 *              this funciton is called.  This is in effect the inverse
 *              of scsi_allocate_device/scsi_request_queueable.
 */
void
scsi_release_command(Scsi_Cmnd * SCpnt)
{
  SCpnt->request.rq_status = RQ_INACTIVE;
  SCpnt->state = SCSI_STATE_UNUSED;
  SCpnt->owner = SCSI_OWNER_NOBODY;
  atomic_dec(&SCpnt->host->host_active); 

  SCSI_LOG_MLQUEUE(5, printk("Deactivating command for device %d (active=%d, failed=%d)\n", 
                             SCpnt->target,
                             atomic_read(&SCpnt->host->host_active),
                             SCpnt->host->host_failed));
  if( SCpnt->host->host_failed != 0 )
    {
      SCSI_LOG_ERROR_RECOVERY(5, printk("Error handler thread %d %d\n", 
                                 SCpnt->host->in_recovery,
                                 SCpnt->host->eh_active));
    }

  /*
   * If the host is having troubles, then look to see if this was the last
   * command that might have failed.  If so, wake up the error handler.
   */
  if( SCpnt->host->in_recovery
      && !SCpnt->host->eh_active
      && atomic_read(&SCpnt->host->host_active) == SCpnt->host->host_failed )
  {
      SCSI_LOG_ERROR_RECOVERY(5, printk("Waking error handler thread (%d)\n",
                                 atomic_read(&SCpnt->host->eh_wait->count)));
      up(SCpnt->host->eh_wait);
  }
}

/*
 * This is inline because we have stack problemes if we recurse to deeply.
 */

inline int internal_cmnd (Scsi_Cmnd * SCpnt)
{
#ifdef DEBUG_DELAY
    unsigned long clock;
#endif
    unsigned long        flags;
    struct Scsi_Host   * host;
    int                  rtn = 0;
    unsigned long        timeout;

#if DEBUG
    unsigned long *ret = 0;
#ifdef __mips__
    __asm__ __volatile__ ("move\t%0,$31":"=r"(ret));
#else
   ret =  __builtin_return_address(0);
#endif
#endif

    host = SCpnt->host;

    save_flags(flags);
    cli();
    /* Assign a unique nonzero serial_number. */
    if (++serial_number == 0) serial_number = 1;
    SCpnt->serial_number = serial_number;

    /*
     * We will wait MIN_RESET_DELAY clock ticks after the last reset so
     * we can avoid the drive not being ready.
     */
    timeout = host->last_reset + MIN_RESET_DELAY;
    if (jiffies < timeout) {
        int ticks_remaining = timeout - jiffies;
        /*
         * NOTE: This may be executed from within an interrupt
         * handler!  This is bad, but for now, it'll do.  The irq
         * level of the interrupt handler has been masked out by the
         * platform dependent interrupt handling code already, so the
         * sti() here will not cause another call to the SCSI host's
         * interrupt handler (assuming there is one irq-level per
         * host).
         */
        sti();
        while (--ticks_remaining >= 0) udelay(1000000/HZ);
        host->last_reset = jiffies - MIN_RESET_DELAY;
    }
    restore_flags(flags);

    if( host->hostt->use_new_eh_code )
      {
        scsi_add_timer(SCpnt, SCpnt->timeout_per_command, scsi_times_out);
      }
    else
      {
        scsi_add_timer(SCpnt, SCpnt->timeout_per_command, 
                            scsi_old_times_out);
      }

    /*
     * We will use a queued command if possible, otherwise we will emulate the
     * queuing and calling of completion function ourselves.
     */
    SCSI_LOG_MLQUEUE(3,printk("internal_cmnd (host = %d, channel = %d, target = %d, "
           "command = %p, buffer = %p, \nbufflen = %d, done = %p)\n",
           SCpnt->host->host_no, SCpnt->channel, SCpnt->target, SCpnt->cmnd,
           SCpnt->buffer, SCpnt->bufflen, SCpnt->done));

    SCpnt->state = SCSI_STATE_QUEUED;
    SCpnt->owner = SCSI_OWNER_LOWLEVEL;
    if (host->can_queue)
    {
        SCSI_LOG_MLQUEUE(3,printk("queuecommand : routine at %p\n",
                                  host->hostt->queuecommand));
        /* This locking tries to prevent all sorts of races between
         * queuecommand and the interrupt code.  In effect,
         * we are only allowed to be in queuecommand once at
         * any given time, and we can only be in the interrupt
         * handler and the queuecommand function at the same time
         * when queuecommand is called while servicing the
         * interrupt.
         */

        if(!in_interrupt() && SCpnt->host->irq)
            disable_irq(SCpnt->host->irq);

        /*
         * Use the old error handling code if we haven't converted the driver
         * to use the new one yet.  Note - only the new queuecommand variant
         * passes a meaningful return value.
         */
        if( host->hostt->use_new_eh_code )
          {
            rtn = host->hostt->queuecommand (SCpnt, scsi_done);
            if( rtn != 0 )
            {
                scsi_mlqueue_insert(SCpnt, SCSI_MLQUEUE_HOST_BUSY);
            }
          }
        else
          {
            host->hostt->queuecommand (SCpnt, scsi_old_done);
          }

        if(!in_interrupt() && SCpnt->host->irq)
            enable_irq(SCpnt->host->irq);
    }
    else
    {
        int temp;

        SCSI_LOG_MLQUEUE(3,printk("command() :  routine at %p\n", host->hostt->command));
        temp = host->hostt->command (SCpnt);
        SCpnt->result = temp;
#ifdef DEBUG_DELAY
        clock = jiffies + 4 * HZ;
        while (jiffies < clock) barrier();
        printk("done(host = %d, result = %04x) : routine at %p\n",
               host->host_no, temp, host->hostt->command);
#endif
        if( host->hostt->use_new_eh_code )
          {
            scsi_done(SCpnt);
          }
        else
          {
            scsi_old_done(SCpnt);
          }
    }
    SCSI_LOG_MLQUEUE(3,printk("leaving internal_cmnd()\n"));
    return rtn;
}

/*
 * scsi_do_cmd sends all the commands out to the low-level driver.  It
 * handles the specifics required for each low level driver - ie queued
 * or non queued.  It also prevents conflicts when different high level
 * drivers go for the same host at the same time.
 */

void scsi_do_cmd (Scsi_Cmnd * SCpnt, const void *cmnd ,
                  void *buffer, unsigned bufflen, void (*done)(Scsi_Cmnd *),
                  int timeout, int retries)
{
    unsigned long flags;
    struct Scsi_Host * host = SCpnt->host;
    Scsi_Device      * device = SCpnt->device;

    SCpnt->owner = SCSI_OWNER_MIDLEVEL;

SCSI_LOG_MLQUEUE(4,
    {
        int i;
        int target = SCpnt->target;
        printk ("scsi_do_cmd (host = %d, channel = %d target = %d, "
                "buffer =%p, bufflen = %d, done = %p, timeout = %d, "
                "retries = %d)\n"
                "command : " , host->host_no, SCpnt->channel, target, buffer,
                bufflen, done, timeout, retries);
        for (i = 0; i < 10; ++i)
            printk ("%02x  ", ((unsigned char *) cmnd)[i]);
        printk("\n");
    });

    if (!host)
    {
        panic ("Invalid or not present host.\n");
    }


    /*
     * We must prevent reentrancy to the lowlevel host driver.  This prevents
     * it - we enter a loop until the host we want to talk to is not busy.
     * Race conditions are prevented, as interrupts are disabled in between the
     * time we check for the host being not busy, and the time we mark it busy
     * ourselves.
     */

    save_flags(flags);
    cli();
    SCpnt->pid = scsi_pid++;

    while (SCSI_BLOCK((Scsi_Device *) NULL, host)) {
        restore_flags(flags);
        SCSI_SLEEP(&host->host_wait, SCSI_BLOCK((Scsi_Device *) NULL, host));
        cli();
    }

    if (host->block) host_active = host;

    host->host_busy++;
    device->device_busy++;
    restore_flags(flags);

    /*
     * Our own function scsi_done (which marks the host as not busy, disables
     * the timeout counter, etc) will be called by us or by the
     * scsi_hosts[host].queuecommand() function needs to also call
     * the completion function for the high level driver.
     */

    memcpy ((void *) SCpnt->data_cmnd , (const void *) cmnd, 12);
    SCpnt->reset_chain = NULL;
    SCpnt->serial_number = 0;
    SCpnt->bufflen = bufflen;
    SCpnt->buffer = buffer;
    SCpnt->flags = 0;
    SCpnt->retries = 0;
    SCpnt->allowed = retries;
    SCpnt->done = done;
    SCpnt->timeout_per_command = timeout;

    memcpy ((void *) SCpnt->cmnd , (const void *) cmnd, 12);
    /* Zero the sense buffer.  Some host adapters automatically request
     * sense on error.  0 is not a valid sense code.
     */
    memset ((void *) SCpnt->sense_buffer, 0, sizeof SCpnt->sense_buffer);
    SCpnt->request_buffer = buffer;
    SCpnt->request_bufflen = bufflen;
    SCpnt->old_use_sg = SCpnt->use_sg;
    if (SCpnt->cmd_len == 0)
        SCpnt->cmd_len = COMMAND_SIZE(SCpnt->cmnd[0]);
    SCpnt->old_cmd_len = SCpnt->cmd_len;

    /* Start the timer ticking.  */

    SCpnt->internal_timeout = NORMAL_TIMEOUT;
    SCpnt->abort_reason = 0;
    internal_cmnd (SCpnt);

    SCSI_LOG_MLQUEUE(3,printk ("Leaving scsi_do_cmd()\n"));
}

/* This function is the mid-level interrupt routine, which decides how
 *  to handle error conditions.  Each invocation of this function must
 *  do one and *only* one of the following:
 *
 *      1) Insert command in BH queue.
 *      2) Activate error handler for host.
 *
 * FIXME(eric) - I am concerned about stack overflow (still).  An interrupt could
 * come while we are processing the bottom queue, which would cause another command
 * to be stuffed onto the bottom queue, and it would in turn be processed as that
 * interrupt handler is returning.  Given a sufficiently steady rate of returning
 * commands, this could cause the stack to overflow.  I am not sure what is the most
 * appropriate solution here - we should probably keep a depth count, and not process
 * any commands while we still have a bottom handler active higher in the stack.
 *
 * There is currently code in the bottom half handler to monitor recursion in the bottom
 * handler and report if it ever happens.  If this becomes a problem, it won't be hard to
 * engineer something to deal with it so that only the outer layer ever does any real
 * processing.
 */
void
scsi_done (Scsi_Cmnd * SCpnt)
{
  unsigned long      flags;
  Scsi_Cmnd        * SCswap;

  /*
   * We don't have to worry about this one timing out any more.
   */
  scsi_delete_timer(SCpnt);

  /*
   * First, see whether this command already timed out.  If so, we ignore
   * the response.  We treat it as if the command never finished.
   */
  if( SCpnt->state == SCSI_STATE_TIMEOUT )
    {
      SCSI_LOG_MLCOMPLETE(1,printk("Ignoring completion of %p due to timeout status", SCpnt));
      return;
    }

  SCpnt->state = SCSI_STATE_BHQUEUE;
  SCpnt->owner = SCSI_OWNER_BH_HANDLER;
  SCpnt->bh_next = NULL;

  /*
   * Next, put this command in the BH queue.  All processing of the command
   * past this point will take place with interrupts turned on.
   * We start by atomicly swapping the pointer into the queue head slot.
   * If it was NULL before, then everything is fine, and we are done
   * (this is the normal case).  If it was not NULL, then we block interrupts,
   * and link them together.
   */
  
  SCswap = (Scsi_Cmnd *) xchg(&scsi_bh_queue_head, SCpnt);
  if( SCswap != NULL )
  {
      /*
       * If we assume that the interrupt handler doesn't dawdle, then it is safe to
       * say that we should come in here extremely rarely.  Under very heavy load,
       * the requests might not be removed from the list fast enough so that we
       * *do* end up stacking them, and that would be bad.
       */
      save_flags(flags);
      cli();
      
      /*
       * See if the pointer is NULL - it might have been serviced already
       */
      if( scsi_bh_queue_head == NULL )
      {
          scsi_bh_queue_head = SCswap;
      }
      else
      {
          SCswap->bh_next = scsi_bh_queue_head;
          scsi_bh_queue_head = SCswap;
      }
      
      restore_flags(flags);
  }

  /*
   * Mark the bottom half handler to be run.
   */
  mark_bh(SCSI_BH);
}

/*
 * Procedure:   scsi_bottom_half_handler
 *
 * Purpose:     Called after we have finished processing interrupts, it
 *              performs post-interrupt handling for commands that may
 *              have completed.
 *
 * Notes:       This is called with all interrupts enabled.  This should reduce
 *              interrupt latency, stack depth, and reentrancy of the low-level
 *              drivers.
 */
void scsi_bottom_half_handler(void)
{
  Scsi_Cmnd        * SCpnt;
  Scsi_Cmnd        * SCnext;
  static atomic_t    recursion_depth;

  
  while(1==1)
  {
      /*
       * If the counter is > 0, that means that there is another interrupt handler
       * out there somewhere processing commands.  We don't want to get these guys
       * nested as this can lead to stack overflow problems, and there isn't any
       * real sense in it anyways.
       */
      if( atomic_read(&recursion_depth) > 0 )
      {
          printk("SCSI bottom half recursion depth = %d \n", atomic_read(&recursion_depth));
          SCSI_LOG_MLCOMPLETE(1,printk("SCSI bottom half recursion depth = %d \n", 
                                       atomic_read(&recursion_depth)));
          break;
      }
      
      /*
       * This is an atomic operation - swap the pointer with a NULL pointer
       * We will process everything we find in the list here.
       */
      SCpnt = xchg(&scsi_bh_queue_head, NULL);
      
      if( SCpnt == NULL )
      {
          return;
      }
      
      atomic_inc(&recursion_depth);
      
      SCnext = SCpnt->bh_next;
      
      for(; SCpnt; SCpnt = SCnext)
      {
          SCnext = SCpnt->bh_next;
          
          switch( scsi_decide_disposition(SCpnt) )
          {
          case SUCCESS:
              /*
               * Add to BH queue.
               */
              SCSI_LOG_MLCOMPLETE(3,printk("Command finished %d %d 0x%x\n", SCpnt->host->host_busy,
                     SCpnt->host->host_failed,
                     SCpnt->result));
              
              scsi_finish_command(SCpnt);
              break;
          case NEEDS_RETRY:
              /*
               * We only come in here if we want to retry a command.  The
               * test to see whether the command should be retried should be
               * keeping track of the number of tries, so we don't end up looping,
               * of course.
               */
              SCSI_LOG_MLCOMPLETE(3,printk("Command needs retry %d %d 0x%x\n", SCpnt->host->host_busy,
                     SCpnt->host->host_failed, SCpnt->result));
              
              scsi_retry_command(SCpnt);
              break;
          case ADD_TO_MLQUEUE:
              /* 
               * This typically happens for a QUEUE_FULL message -
               * typically only when the queue depth is only
               * approximate for a given device.  Adding a command
               * to the queue for the device will prevent further commands
               * from being sent to the device, so we shouldn't end up
               * with tons of things being sent down that shouldn't be.
               */
              scsi_mlqueue_insert(SCpnt, SCSI_MLQUEUE_DEVICE_BUSY);
              break;
          default:
              /*
               * Here we have a fatal error of some sort.  Turn it over to
               * the error handler.
               */
              SCSI_LOG_MLCOMPLETE(3,printk("Command failed %p %x active=%d busy=%d failed=%d\n", 
                                           SCpnt, SCpnt->result,
                                           atomic_read(&SCpnt->host->host_active),
                                           SCpnt->host->host_busy,
                                           SCpnt->host->host_failed));
              
              /*
               * Dump the sense information too.
               */
              if ((status_byte (SCpnt->result) & CHECK_CONDITION) != 0)
              {
                  SCSI_LOG_MLCOMPLETE(3,print_sense("bh",SCpnt));
              }


              if( SCpnt->host->eh_wait != NULL )
              {
                  SCpnt->host->host_failed++;
                  SCpnt->owner = SCSI_OWNER_ERROR_HANDLER;
                  SCpnt->state = SCSI_STATE_FAILED;
                  SCpnt->host->in_recovery = 1;
                  /*
                   * If the host is having troubles, then look to see if this was the last
                   * command that might have failed.  If so, wake up the error handler.
                   */
                  if( atomic_read(&SCpnt->host->host_active) == SCpnt->host->host_failed )
                  {
                    SCSI_LOG_ERROR_RECOVERY(5, printk("Waking error handler thread (%d)\n",
                                                      atomic_read(&SCpnt->host->eh_wait->count)));
                      up(SCpnt->host->eh_wait);
                  }
              }
              else
              {
                  /*
                   * We only get here if the error recovery thread has died.
                   */
                  scsi_finish_command(SCpnt);
              }
          }
      } /* for(; SCpnt...) */

      atomic_dec(&recursion_depth);

  } /* while(1==1) */

}

/*
 * Function:    scsi_retry_command
 *
 * Purpose:     Send a command back to the low level to be retried.
 *
 * Notes:       This command is always executed in the context of the
 *              bottom half handler, or the error handler thread. Low
 *              level drivers should not become re-entrant as a result of
 *              this.
 */
int
scsi_retry_command(Scsi_Cmnd * SCpnt)
{
  memcpy ((void *) SCpnt->cmnd,  (void*) SCpnt->data_cmnd,
          sizeof(SCpnt->data_cmnd));
  SCpnt->request_buffer = SCpnt->buffer;
  SCpnt->request_bufflen = SCpnt->bufflen;
  SCpnt->use_sg = SCpnt->old_use_sg;
  SCpnt->cmd_len = SCpnt->old_cmd_len;
  return internal_cmnd (SCpnt);
}

/*
 * Function:    scsi_finish_command
 *
 * Purpose:     Pass command off to upper layer for finishing of I/O
 *              request, waking processes that are waiting on results,
 *              etc.
 */
void
scsi_finish_command(Scsi_Cmnd * SCpnt)
{
    struct Scsi_Host * host;
    Scsi_Device * device;

    host = SCpnt->host;
    device = SCpnt->device;

    host->host_busy--; /* Indicate that we are free */
    device->device_busy--; /* Decrement device usage counter. */
  
    if (host->block && host->host_busy == 0) 
    {
        host_active = NULL;
        
        /* For block devices "wake_up" is done in end_scsi_request */
        if (MAJOR(SCpnt->request.rq_dev) != SCSI_DISK_MAJOR &&
            MAJOR(SCpnt->request.rq_dev) != SCSI_CDROM_MAJOR) {
            struct Scsi_Host * next;
            
            for (next = host->block; next != host; next = next->block)
                wake_up(&next->host_wait);
        }
        
    }
  
    /*
     * Now try and drain the mid-level queue if any commands have been
     * inserted.  Check to see whether the queue even has anything in
     * it first, as otherwise this is useless overhead.
     */
    if( SCpnt->host->pending_commands != NULL )
    {
        scsi_mlqueue_finish(SCpnt->host, SCpnt->device);
    }

    wake_up(&host->host_wait);
    
    /*
     * If we have valid sense information, then some kind of recovery
     * must have taken place.  Make a note of this.
     */
    if( scsi_sense_valid(SCpnt) )
    {
        SCpnt->result |= (DRIVER_SENSE << 24);
    }
    
    SCSI_LOG_MLCOMPLETE(3,printk("Notifying upper driver of completion for device %d %x\n",
                                     SCpnt->device->id, SCpnt->result));
    
    SCpnt->owner = SCSI_OWNER_HIGHLEVEL;
    SCpnt->state = SCSI_STATE_FINISHED;
    SCpnt->done (SCpnt);
}

#ifdef CONFIG_MODULES
static int scsi_register_host(Scsi_Host_Template *);
static void scsi_unregister_host(Scsi_Host_Template *);
#endif

void *scsi_malloc(unsigned int len)
{
    unsigned int nbits, mask;
    unsigned long flags;
    int i, j;
    if(len % SECTOR_SIZE != 0 || len > PAGE_SIZE)
        return NULL;

    save_flags(flags);
    cli();
    nbits = len >> 9;
    mask = (1 << nbits) - 1;

    for(i=0;i < dma_sectors / SECTORS_PER_PAGE; i++)
        for(j=0; j<=SECTORS_PER_PAGE - nbits; j++){
            if ((dma_malloc_freelist[i] & (mask << j)) == 0){
                dma_malloc_freelist[i] |= (mask << j);
                restore_flags(flags);
                scsi_dma_free_sectors -= nbits;
#ifdef DEBUG
                SCSI_LOG_MLQUEUE(3,printk("SMalloc: %d %p [From:%p]\n",len, dma_malloc_pages[i] + (j << 9)));
                printk("SMalloc: %d %p [From:%p]\n",len, dma_malloc_pages[i] + (j << 9));
#endif
                return (void *) ((unsigned long) dma_malloc_pages[i] + (j << 9));
            }
        }
    restore_flags(flags);
    return NULL;  /* Nope.  No more */
}

int scsi_free(void *obj, unsigned int len)
{
    unsigned int page, sector, nbits, mask;
    unsigned long flags;

#ifdef DEBUG
    unsigned long ret = 0;

#ifdef __mips__
    __asm__ __volatile__ ("move\t%0,$31":"=r"(ret));
#else
   ret = __builtin_return_address(0);
#endif
    printk("scsi_free %p %d\n",obj, len);
    SCSI_LOG_MLQUEUE(3,printk("SFree: %p %d\n",obj, len));
#endif

    for (page = 0; page < dma_sectors / SECTORS_PER_PAGE; page++) {
        unsigned long page_addr = (unsigned long) dma_malloc_pages[page];
        if ((unsigned long) obj >= page_addr &&
            (unsigned long) obj <  page_addr + PAGE_SIZE)
        {
            sector = (((unsigned long) obj) - page_addr) >> 9;

            nbits = len >> 9;
            mask = (1 << nbits) - 1;

            if ((mask << sector) >= (1 << SECTORS_PER_PAGE))
                panic ("scsi_free:Bad memory alignment");

            save_flags(flags);
            cli();
            if((dma_malloc_freelist[page] &
                (mask << sector)) != (mask<<sector)){
#ifdef DEBUG
                printk("scsi_free(obj=%p, len=%d) called from %08lx\n",
                       obj, len, ret);
#endif
                panic("scsi_free:Trying to free unused memory");
            }
            scsi_dma_free_sectors += nbits;
            dma_malloc_freelist[page] &= ~(mask << sector);
            restore_flags(flags);
            return 0;
        }
    }
    panic("scsi_free:Bad offset");
}


int scsi_loadable_module_flag; /* Set after we scan builtin drivers */

void * scsi_init_malloc(unsigned int size, int gfp_mask)
{
    void * retval;

    /*
     * For buffers used by the DMA pool, we assume page aligned 
     * structures.
     */
    if ((size % PAGE_SIZE) == 0) {
        int order, a_size;
        for (order = 0, a_size = PAGE_SIZE;
             a_size < size; order++, a_size <<= 1)
            ;
        retval = (void *) __get_free_pages(gfp_mask | GFP_DMA, order);
    } else
        retval = kmalloc(size, gfp_mask);

    if (retval)
        memset(retval, 0, size);
    return retval;
}


void scsi_init_free(char * ptr, unsigned int size)
{
    /*
     * We need this special code here because the DMA pool assumes
     * page aligned data.  Besides, it is wasteful to allocate
     * page sized chunks with kmalloc.
     */
    if ((size % PAGE_SIZE) == 0) {
        int order, a_size;

        for (order = 0, a_size = PAGE_SIZE;
             a_size < size; order++, a_size <<= 1)
            ;
        free_pages((unsigned long)ptr, order);
    } else
        kfree(ptr);
}

void scsi_build_commandblocks(Scsi_Device * SDpnt)
{
    struct Scsi_Host *host = SDpnt->host;
    int j;
    Scsi_Cmnd * SCpnt;

    if (SDpnt->queue_depth == 0)
        SDpnt->queue_depth = host->cmd_per_lun;
    SDpnt->device_queue = NULL;

    for(j=0;j<SDpnt->queue_depth;j++){
      SCpnt = (Scsi_Cmnd *)
              scsi_init_malloc(sizeof(Scsi_Cmnd),
                               GFP_ATOMIC |
                               (host->unchecked_isa_dma ? GFP_DMA : 0));
        memset(&SCpnt->eh_timeout, 0, sizeof(SCpnt->eh_timeout));
        SCpnt->host                      = host;
        SCpnt->device                    = SDpnt;
        SCpnt->target                    = SDpnt->id;
        SCpnt->lun                       = SDpnt->lun;
        SCpnt->channel                   = SDpnt->channel;
        SCpnt->request.rq_status         = RQ_INACTIVE;
        SCpnt->host_wait                 = FALSE;
        SCpnt->device_wait               = FALSE;
        SCpnt->use_sg                    = 0;
        SCpnt->old_use_sg                = 0;
        SCpnt->old_cmd_len               = 0;
        SCpnt->underflow                 = 0;
        SCpnt->transfersize              = 0;
        SCpnt->serial_number             = 0;
        SCpnt->serial_number_at_timeout  = 0;
        SCpnt->host_scribble             = NULL;
        SCpnt->next                      = SDpnt->device_queue;
        SDpnt->device_queue              = SCpnt;
        SCpnt->state                     = SCSI_STATE_UNUSED;
        SCpnt->owner                     = SCSI_OWNER_NOBODY;
    }
    SDpnt->has_cmdblocks = 1;
}

#ifndef MODULE /* { */
/*
 * scsi_dev_init() is our initialization routine, which in turn calls host
 * initialization, bus scanning, and sd/st initialization routines.
 * This is only used at boot time.
 */
__initfunc(int scsi_dev_init(void))
{
    Scsi_Device * SDpnt;
    struct Scsi_Host * shpnt;
    struct Scsi_Device_Template * sdtpnt;
#ifdef FOO_ON_YOU
    return;
#endif

    /* Yes we're here... */
#if CONFIG_PROC_FS
    dispatch_scsi_info_ptr = dispatch_scsi_info;
#endif

    /* Init a few things so we can "malloc" memory. */
    scsi_loadable_module_flag = 0;

    /* Register the /proc/scsi/scsi entry */
#if CONFIG_PROC_FS
    proc_scsi_register(0, &proc_scsi_scsi);
#endif

    /* initialize all hosts */
    scsi_init();

    /*
     * This is where the processing takes place for most everything
     * when commands are completed.  Until we do this, we will not be able
     * to queue any commands.
     */
    init_bh(SCSI_BH, scsi_bottom_half_handler);

    for (shpnt = scsi_hostlist; shpnt; shpnt = shpnt->next) {
        scan_scsis(shpnt,0,0,0,0);           /* scan for scsi devices */
        if (shpnt->select_queue_depths != NULL)
            (shpnt->select_queue_depths)(shpnt, shpnt->host_queue);
    }

    printk("scsi : detected ");
    for (sdtpnt = scsi_devicelist; sdtpnt; sdtpnt = sdtpnt->next)
        if (sdtpnt->dev_noticed && sdtpnt->name)
            printk("%d SCSI %s%s ", sdtpnt->dev_noticed, sdtpnt->name,
                   (sdtpnt->dev_noticed != 1) ? "s" : "");
    printk("total.\n");

    for(sdtpnt = scsi_devicelist; sdtpnt; sdtpnt = sdtpnt->next)
        if(sdtpnt->init && sdtpnt->dev_noticed) (*sdtpnt->init)();

    for(shpnt = scsi_hostlist; shpnt; shpnt = shpnt->next)
    {
        for(SDpnt = shpnt->host_queue; SDpnt; SDpnt = SDpnt->next) 
        {
            /* SDpnt->scsi_request_fn = NULL; */
            for(sdtpnt = scsi_devicelist; sdtpnt; sdtpnt = sdtpnt->next)
                if(sdtpnt->attach) (*sdtpnt->attach)(SDpnt);
            if(SDpnt->attached) scsi_build_commandblocks(SDpnt);
        }
    }
    
    /*
     * This should build the DMA pool.
     */
    resize_dma_pool();

    /*
     * OK, now we finish the initialization by doing spin-up, read
     * capacity, etc, etc
     */
    for(sdtpnt = scsi_devicelist; sdtpnt; sdtpnt = sdtpnt->next)
        if(sdtpnt->finish && sdtpnt->nr_dev)
            (*sdtpnt->finish)();

    scsi_loadable_module_flag = 1;

    return 0;
}
#endif /* MODULE */   /* } */

static void print_inquiry(unsigned char *data)
{
    int i;

    printk("  Vendor: ");
    for (i = 8; i < 16; i++)
    {
        if (data[i] >= 0x20 && i < data[4] + 5)
            printk("%c", data[i]);
        else
            printk(" ");
    }

    printk("  Model: ");
    for (i = 16; i < 32; i++)
    {
        if (data[i] >= 0x20 && i < data[4] + 5)
            printk("%c", data[i]);
        else
            printk(" ");
    }

    printk("  Rev: ");
    for (i = 32; i < 36; i++)
    {
        if (data[i] >= 0x20 && i < data[4] + 5)
            printk("%c", data[i]);
        else
            printk(" ");
    }

    printk("\n");

    i = data[0] & 0x1f;

    printk("  Type:   %s ",
           i < MAX_SCSI_DEVICE_CODE ? scsi_device_types[i] : "Unknown          " );
    printk("                 ANSI SCSI revision: %02x", data[2] & 0x07);
    if ((data[2] & 0x07) == 1 && (data[3] & 0x0f) == 1)
        printk(" CCS\n");
    else
        printk("\n");
}


#ifdef CONFIG_PROC_FS
int scsi_proc_info(char *buffer, char **start, off_t offset, int length,
                    int hostno, int inout)
{
    Scsi_Cmnd *SCpnt;
    struct Scsi_Device_Template *SDTpnt;
    Scsi_Device *scd;
    struct Scsi_Host *HBA_ptr;
    char *p;
    int   host, channel, id, lun;
    int   size, len = 0;
    off_t begin = 0;
    off_t pos = 0;

    if(inout == 0) {
        /*
         * First, see if there are any attached devices or not.
         */
        for (HBA_ptr = scsi_hostlist; HBA_ptr; HBA_ptr = HBA_ptr->next)
        {
            if( HBA_ptr->host_queue != NULL )
            {
                break;
            }
        }
        size = sprintf(buffer+len,"Attached devices: %s\n", (HBA_ptr)?"":"none");
        len += size;
        pos = begin + len;
        for (HBA_ptr = scsi_hostlist; HBA_ptr; HBA_ptr = HBA_ptr->next)
        {
#if 0
            size += sprintf(buffer+len,"scsi%2d: %s\n", (int) HBA_ptr->host_no,
                            HBA_ptr->hostt->procname);
            len += size;
            pos = begin + len;
#endif
            for(scd = HBA_ptr->host_queue; scd; scd = scd->next) 
            {
                proc_print_scsidevice(scd, buffer, &size, len);
                len += size;
                pos = begin + len;
                
                if (pos < offset) {
                    len = 0;
                    begin = pos;
                }
                if (pos > offset + length)
                    goto stop_output;
            }
        }

    stop_output:
        *start=buffer+(offset-begin);   /* Start of wanted data */
        len-=(offset-begin);            /* Start slop */
        if(len>length)
            len = length;               /* Ending slop */
        return (len);
    }

    if(!buffer || length < 11 || strncmp("scsi", buffer, 4))
        return(-EINVAL);

    /*
     * Usage: echo "scsi dump #N" > /proc/scsi/scsi
     * to dump status of all scsi commands.  The number is used to specify the level
     * of detail in the dump.
     */
    if(!strncmp("dump", buffer + 5, 4)) 
    {
        unsigned int level;

        p = buffer + 10;

        if( *p == '\0' )
            return (-EINVAL);

        level = simple_strtoul(p, NULL, 0);
        scsi_dump_status(level);
    }
    /*
     * Usage: echo "scsi log token #N" > /proc/scsi/scsi
     * where token is one of [error,scan,mlqueue,mlcomplete,llqueue,
     * llcomplete,hlqueue,hlcomplete]
     */
#if CONFIG_SCSI_LOGGING /* { */

    if(!strncmp("log", buffer + 5, 3)) 
    {
        char * token;
        unsigned int level;

        p = buffer + 9;
        token = p;
        while(*p != ' ' && *p != '\t' && *p != '\0')
        {
            p++;
        }

        if( *p == '\0' )
        {
            if( strncmp(token, "all", 3) == 0 )
            {
                /*
                 * Turn on absolutely everything.
                 */
                scsi_logging_level = ~0;
            }
            else if( strncmp(token, "none", 4) == 0 )
            {
                /*
                 * Turn off absolutely everything.
                 */
                scsi_logging_level = 0;
            }
            else
            {
                return (-EINVAL);
            }
        }
        else
        {
            *p++ = '\0';
            
            level = simple_strtoul(p, NULL, 0);
            
            /*
             * Now figure out what to do with it.
             */
            if( strcmp(token, "error") == 0 )
            {
                SCSI_SET_ERROR_RECOVERY_LOGGING(level);
            }
            else if( strcmp(token, "timeout") == 0 )
            {
                SCSI_SET_TIMEOUT_LOGGING(level);
            }
            else if( strcmp(token, "scan") == 0 )
            {
                SCSI_SET_SCAN_BUS_LOGGING(level);
            }
            else if( strcmp(token, "mlqueue") == 0 )
            {
                SCSI_SET_MLQUEUE_LOGGING(level);
            }
            else if( strcmp(token, "mlcomplete") == 0 )
            {
                SCSI_SET_MLCOMPLETE_LOGGING(level);
            }
            else if( strcmp(token, "llqueue") == 0 )
            {
                SCSI_SET_LLQUEUE_LOGGING(level);
            }
            else if( strcmp(token, "llcomplete") == 0 )
            {
                SCSI_SET_LLCOMPLETE_LOGGING(level);
            }
            else if( strcmp(token, "hlqueue") == 0 )
            {
                SCSI_SET_HLQUEUE_LOGGING(level);
            }
            else if( strcmp(token, "hlcomplete") == 0 )
            {
                SCSI_SET_HLCOMPLETE_LOGGING(level);
            }
            else if( strcmp(token, "ioctl") == 0 )
            {
                SCSI_SET_IOCTL_LOGGING(level);
            }
            else
            {
                return (-EINVAL);
            }
        }

        printk("scsi logging level set to 0x%8.8x\n", scsi_logging_level);
    }
#endif /* CONFIG_SCSI_LOGGING */ /* } */

    /*
     * Usage: echo "scsi add-single-device 0 1 2 3" >/proc/scsi/scsi
     * with  "0 1 2 3" replaced by your "Host Channel Id Lun".
     * Consider this feature BETA.
     *     CAUTION: This is not for hotplugging your peripherals. As
     *     SCSI was not designed for this you could damage your
     *     hardware !
     * However perhaps it is legal to switch on an
     * already connected device. It is perhaps not
     * guaranteed this device doesn't corrupt an ongoing data transfer.
     */
    if(!strncmp("add-single-device", buffer + 5, 17)) {
        p = buffer + 23;

        host    = simple_strtoul(p, &p, 0);
        channel = simple_strtoul(p+1, &p, 0);
        id      = simple_strtoul(p+1, &p, 0);
        lun     = simple_strtoul(p+1, &p, 0);

        printk("scsi singledevice %d %d %d %d\n", host, channel,
                        id, lun);

        for(HBA_ptr = scsi_hostlist; HBA_ptr; HBA_ptr = HBA_ptr->next)
        {
            if( HBA_ptr->host_no == host )
            {
                break;
            }
        }
        if(!HBA_ptr)
            return(-ENXIO);

        for(scd = HBA_ptr->host_queue; scd; scd = scd->next) 
        {
            if((scd->channel == channel
                && scd->id == id
                && scd->lun == lun))
            {
                break;
            }
        }

        if(scd)
            return(-ENOSYS);  /* We do not yet support unplugging */

        scan_scsis (HBA_ptr, 1, channel, id, lun);
        return(length);

    }

    /*
     * Usage: echo "scsi remove-single-device 0 1 2 3" >/proc/scsi/scsi
     * with  "0 1 2 3" replaced by your "Host Channel Id Lun".
     *
     * Consider this feature pre-BETA.
     *
     *     CAUTION: This is not for hotplugging your peripherals. As
     *     SCSI was not designed for this you could damage your
     *     hardware and thoroughly confuse the SCSI subsystem.
     *
     */
    else if(!strncmp("remove-single-device", buffer + 5, 20)) {
        p = buffer + 26;

        host    = simple_strtoul(p, &p, 0);
        channel = simple_strtoul(p+1, &p, 0);
        id      = simple_strtoul(p+1, &p, 0);
        lun     = simple_strtoul(p+1, &p, 0);


        for(HBA_ptr = scsi_hostlist; HBA_ptr; HBA_ptr = HBA_ptr->next)
        {
            if( HBA_ptr->host_no == host )
            {
                break;
            }
        }
        if(!HBA_ptr)
            return(-ENODEV);

        for(scd = HBA_ptr->host_queue; scd; scd = scd->next) 
        {
            if((scd->channel == channel
                && scd->id == id
                && scd->lun == lun))
            {
                break;
            }
        }

        if(scd == NULL)
            return(-ENODEV);  /* there is no such device attached */

        if(scd->access_count)
            return(-EBUSY);

        SDTpnt = scsi_devicelist;
        while(SDTpnt != NULL) {
            if(SDTpnt->detach) (*SDTpnt->detach)(scd);
            SDTpnt = SDTpnt->next;
        }

        if(scd->attached == 0) {
            /*
             * Nobody is using this device any more.
             * Free all of the command structures.
             */
            for(SCpnt=scd->device_queue; SCpnt; SCpnt = SCpnt->next)
            {
                scd->device_queue = SCpnt->next;
                scsi_init_free((char *) SCpnt, sizeof(*SCpnt));
            }
            /* Now we can remove the device structure */
            if( scd->next != NULL )
                scd->next->prev = scd->prev;

            if( scd->prev != NULL )
                scd->prev->next = scd->next;

            if( HBA_ptr->host_queue == scd )
            {
                HBA_ptr->host_queue = scd->next;
            }

            scsi_init_free((char *) scd, sizeof(Scsi_Device));
        } else {
            return(-EBUSY);
        }
        return(0);
    }
    return(-EINVAL);
}
#endif

/*
 * Go through the device list and recompute the most appropriate size
 * for the dma pool.  Then grab more memory (as required).
 */
static void resize_dma_pool(void)
{
    int i;
    unsigned long size;
    struct Scsi_Host * shpnt;
    struct Scsi_Host * host = NULL;
    Scsi_Device * SDpnt;
    unsigned long flags;
    FreeSectorBitmap * new_dma_malloc_freelist = NULL;
    unsigned int new_dma_sectors = 0;
    unsigned int new_need_isa_buffer = 0;
    unsigned char ** new_dma_malloc_pages = NULL;

    if( !scsi_hostlist )
    {
        /*
         * Free up the DMA pool.
         */
        if( scsi_dma_free_sectors != dma_sectors )
            panic("SCSI DMA pool memory leak %d %d\n",scsi_dma_free_sectors,dma_sectors);

        for(i=0; i < dma_sectors / SECTORS_PER_PAGE; i++)
            scsi_init_free(dma_malloc_pages[i], PAGE_SIZE);
        if (dma_malloc_pages)
            scsi_init_free((char *) dma_malloc_pages,
                           (dma_sectors / SECTORS_PER_PAGE)*sizeof(*dma_malloc_pages));
        dma_malloc_pages = NULL;
        if (dma_malloc_freelist)
            scsi_init_free((char *) dma_malloc_freelist,
                           (dma_sectors / SECTORS_PER_PAGE)*sizeof(*dma_malloc_freelist));
        dma_malloc_freelist = NULL;
        dma_sectors = 0;
        scsi_dma_free_sectors = 0;
        return;
    }
    /* Next, check to see if we need to extend the DMA buffer pool */

    new_dma_sectors = 2*SECTORS_PER_PAGE;               /* Base value we use */

    if (__pa(high_memory)-1 > ISA_DMA_THRESHOLD)
        need_isa_bounce_buffers = 1;
    else
        need_isa_bounce_buffers = 0;

    if (scsi_devicelist)
        for(shpnt=scsi_hostlist; shpnt; shpnt = shpnt->next)
            new_dma_sectors += SECTORS_PER_PAGE;        /* Increment for each host */

    for (host = scsi_hostlist; host; host = host->next)
    {
        for (SDpnt=host->host_queue; SDpnt; SDpnt = SDpnt->next) 
        {
            /*
             * sd and sr drivers allocate scatterlists.
             * sr drivers may allocate for each command 1x2048 or 2x1024 extra
             * buffers for 2k sector size and 1k fs.
             * sg driver allocates buffers < 4k.
             * st driver does not need buffers from the dma pool.
             * estimate 4k buffer/command for devices of unknown type (should panic).
             */
            if (SDpnt->type == TYPE_WORM || SDpnt->type == TYPE_ROM ||
                SDpnt->type == TYPE_DISK || SDpnt->type == TYPE_MOD) {
                new_dma_sectors += ((host->sg_tablesize *
                                     sizeof(struct scatterlist) + 511) >> 9) *
                    SDpnt->queue_depth;
                if (SDpnt->type == TYPE_WORM || SDpnt->type == TYPE_ROM)
                    new_dma_sectors += (2048 >> 9) * SDpnt->queue_depth;
            }
            else if (SDpnt->type == TYPE_SCANNER ||
                     SDpnt->type == TYPE_PROCESSOR ||
                     SDpnt->type == TYPE_MEDIUM_CHANGER) {
                new_dma_sectors += (4096 >> 9) * SDpnt->queue_depth;
            }
            else {
                if (SDpnt->type != TYPE_TAPE) {
                    printk("resize_dma_pool: unknown device type %d\n", SDpnt->type);
                    new_dma_sectors += (4096 >> 9) * SDpnt->queue_depth;
                }
            }
            
            if(host->unchecked_isa_dma &&
               need_isa_bounce_buffers &&
               SDpnt->type != TYPE_TAPE) {
                new_dma_sectors += (PAGE_SIZE >> 9) * host->sg_tablesize *
                    SDpnt->queue_depth;
                new_need_isa_buffer++;
            }
        }
    }

#ifdef DEBUG_INIT
    printk("resize_dma_pool: needed dma sectors = %d\n", new_dma_sectors);
#endif

    /* limit DMA memory to 32MB: */
    new_dma_sectors = (new_dma_sectors + 15) & 0xfff0;

    /*
     * We never shrink the buffers - this leads to
     * race conditions that I would rather not even think
     * about right now.
     */
    if( new_dma_sectors < dma_sectors )
        new_dma_sectors = dma_sectors;

    if (new_dma_sectors)
    {
        size = (new_dma_sectors / SECTORS_PER_PAGE)*sizeof(FreeSectorBitmap);
        new_dma_malloc_freelist = (FreeSectorBitmap *) scsi_init_malloc(size, GFP_ATOMIC);
        memset(new_dma_malloc_freelist, 0, size);

        size = (new_dma_sectors / SECTORS_PER_PAGE)*sizeof(*new_dma_malloc_pages);
        new_dma_malloc_pages = (unsigned char **) scsi_init_malloc(size, GFP_ATOMIC);
        memset(new_dma_malloc_pages, 0, size);
    }

    /*
     * If we need more buffers, expand the list.
     */
    if( new_dma_sectors > dma_sectors ) { 
        for(i=dma_sectors / SECTORS_PER_PAGE; i< new_dma_sectors / SECTORS_PER_PAGE; i++)
            new_dma_malloc_pages[i] = (unsigned char *)
                scsi_init_malloc(PAGE_SIZE, GFP_ATOMIC | GFP_DMA);
    }

    /* When we dick with the actual DMA list, we need to
     * protect things
     */
    save_flags(flags);
    cli();
    if (dma_malloc_freelist)
    {
        size = (dma_sectors / SECTORS_PER_PAGE)*sizeof(FreeSectorBitmap);
        memcpy(new_dma_malloc_freelist, dma_malloc_freelist, size);
        scsi_init_free((char *) dma_malloc_freelist, size);
    }
    dma_malloc_freelist = new_dma_malloc_freelist;

    if (dma_malloc_pages)
    {
        size = (dma_sectors / SECTORS_PER_PAGE)*sizeof(*dma_malloc_pages);
        memcpy(new_dma_malloc_pages, dma_malloc_pages, size);
        scsi_init_free((char *) dma_malloc_pages, size);
    }

    scsi_dma_free_sectors += new_dma_sectors - dma_sectors;
    dma_malloc_pages = new_dma_malloc_pages;
    dma_sectors = new_dma_sectors;
    scsi_need_isa_buffer = new_need_isa_buffer;
    restore_flags(flags);

#ifdef DEBUG_INIT
    printk("resize_dma_pool: dma free sectors   = %d\n", scsi_dma_free_sectors);
    printk("resize_dma_pool: dma sectors        = %d\n", dma_sectors);
    printk("resize_dma_pool: need isa buffers   = %d\n", scsi_need_isa_buffer);
#endif
}

#ifdef CONFIG_MODULES           /* a big #ifdef block... */

/*
 * This entry point should be called by a loadable module if it is trying
 * add a low level scsi driver to the system.
 */
static int scsi_register_host(Scsi_Host_Template * tpnt)
{
    int pcount;
    struct Scsi_Host * shpnt;
    Scsi_Device * SDpnt;
    struct Scsi_Device_Template * sdtpnt;
    const char * name;

    if (tpnt->next || !tpnt->detect) return 1;/* Must be already loaded, or
                                               * no detect routine available
                                               */
    pcount = next_scsi_host;
    if ((tpnt->present = tpnt->detect(tpnt)))
    {
        if(pcount == next_scsi_host) 
        {
            if(tpnt->present > 1) 
            {
                printk("Failure to register low-level scsi driver");
                scsi_unregister_host(tpnt);
                return 1;
            }
            /* 
             * The low-level driver failed to register a driver.  We
             *  can do this now.
             */
            scsi_register(tpnt,0);
        }
        tpnt->next = scsi_hosts; /* Add to the linked list */
        scsi_hosts = tpnt;

        /* Add the new driver to /proc/scsi */
#if CONFIG_PROC_FS
        build_proc_dir_entries(tpnt);
#endif


        /*
         * Add the kernel threads for each host adapter that will
         * handle error correction.
         */
        for(shpnt=scsi_hostlist; shpnt; shpnt = shpnt->next)
        {
            if( shpnt->hostt == tpnt && shpnt->hostt->use_new_eh_code )
            {
                struct semaphore sem = MUTEX_LOCKED;
                
                shpnt->eh_notify = &sem;
                kernel_thread((int (*)(void *))scsi_error_handler, 
                              (void *) shpnt, 0);
                
                /*
                 * Now wait for the kernel error thread to initialize itself
                 * as it might be needed when we scan the bus.
                 */
                down (&sem);
                shpnt->eh_notify = NULL;
            }
        }
        
        for(shpnt=scsi_hostlist; shpnt; shpnt = shpnt->next)
        {
            if(shpnt->hostt == tpnt)
            {
                if(tpnt->info)
                {
                    name = tpnt->info(shpnt);
                }
                else
                {
                    name = tpnt->name;
                }
                printk ("scsi%d : %s\n", /* And print a little message */
                        shpnt->host_no, name);
            }
        }

        printk ("scsi : %d host%s.\n", next_scsi_host,
                (next_scsi_host == 1) ? "" : "s");

        scsi_make_blocked_list();

        /* The next step is to call scan_scsis here.  This generates the
         * Scsi_Devices entries
         */
        for(shpnt=scsi_hostlist; shpnt; shpnt = shpnt->next)
        {
            if(shpnt->hostt == tpnt) 
            {
                scan_scsis(shpnt,0,0,0,0);
                if (shpnt->select_queue_depths != NULL)
                {
                    (shpnt->select_queue_depths)(shpnt, shpnt->host_queue);
                }
            }
        }

        for(sdtpnt = scsi_devicelist; sdtpnt; sdtpnt = sdtpnt->next)
        {
            if(sdtpnt->init && sdtpnt->dev_noticed) (*sdtpnt->init)();
        }

        /*
         * Next we create the Scsi_Cmnd structures for this host 
         */
        for(shpnt = scsi_hostlist; shpnt; shpnt = shpnt->next)
        {
            for(SDpnt = shpnt->host_queue; SDpnt; SDpnt = SDpnt->next)
                if(SDpnt->host->hostt == tpnt)
                {
                    for(sdtpnt = scsi_devicelist; sdtpnt; sdtpnt = sdtpnt->next)
                        if(sdtpnt->attach) (*sdtpnt->attach)(SDpnt);
                    if(SDpnt->attached) scsi_build_commandblocks(SDpnt);
                }
        }

        /*
         * Now that we have all of the devices, resize the DMA pool,
         * as required.  */
        resize_dma_pool();


        /* This does any final handling that is required. */
        for(sdtpnt = scsi_devicelist; sdtpnt; sdtpnt = sdtpnt->next)
        {
            if(sdtpnt->finish && sdtpnt->nr_dev)
            {
                (*sdtpnt->finish)();
            }
        }
    }

#if defined(USE_STATIC_SCSI_MEMORY)
    printk ("SCSI memory: total %ldKb, used %ldKb, free %ldKb.\n",
            (scsi_memory_upper_value - scsi_memory_lower_value) / 1024,
            (scsi_init_memory_start - scsi_memory_lower_value) / 1024,
            (scsi_memory_upper_value - scsi_init_memory_start) / 1024);
#endif

    MOD_INC_USE_COUNT;
    return 0;
}

/*
 * Similarly, this entry point should be called by a loadable module if it
 * is trying to remove a low level scsi driver from the system.
 *
 * Note - there is a fatal flaw in the deregister module function.
 * There is no way to return a code that says 'I cannot be unloaded now'.
 * The system relies entirely upon usage counts that are maintained,
 * and the assumption is that if the usage count is 0, then the module
 * can be unloaded.
 */
static void scsi_unregister_host(Scsi_Host_Template * tpnt)
{
    unsigned long                 flags;
    int                           online_status;
    int                           pcount;
    Scsi_Cmnd                   * SCpnt;
    Scsi_Device                 * SDpnt;
    Scsi_Device                 * SDpnt1;
    struct Scsi_Device_Template * sdtpnt;
    struct Scsi_Host            * sh1;
    struct Scsi_Host            * shpnt;
    Scsi_Host_Template          * SHT;
    Scsi_Host_Template          * SHTp;

    /*
     * First verify that this host adapter is completely free with no pending
     * commands 
     */
    for(shpnt = scsi_hostlist; shpnt; shpnt = shpnt->next)
    {
        for(SDpnt = shpnt->host_queue; SDpnt; 
            SDpnt = SDpnt->next)
        {
            if(SDpnt->host->hostt == tpnt 
               && SDpnt->host->hostt->module
               && SDpnt->host->hostt->module->usecount) return;
            /* 
             * FIXME(eric) - We need to find a way to notify the
             * low level driver that we are shutting down - via the
             * special device entry that still needs to get added. 
             *
             * Is detach interface below good enough for this?
             */
        }
    }

    /*
     * FIXME(eric) put a spinlock on this.  We force all of the devices offline
     * to help prevent race conditions where other hosts/processors could try and
     * get in and queue a command.
     */
    for(shpnt = scsi_hostlist; shpnt; shpnt = shpnt->next)
    {
        for(SDpnt = shpnt->host_queue; SDpnt; 
            SDpnt = SDpnt->next)
        {
            if(SDpnt->host->hostt == tpnt )
                SDpnt->online = FALSE;

        }
    }

    for(shpnt = scsi_hostlist; shpnt; shpnt = shpnt->next)
    {
        if (shpnt->hostt != tpnt)
        {
            continue;
        }

        for(SDpnt = shpnt->host_queue; SDpnt; 
            SDpnt = SDpnt->next)
        {
            /*
             * Loop over all of the commands associated with the device.  If any of
             * them are busy, then set the state back to inactive and bail.
             */
            for(SCpnt = SDpnt->device_queue; SCpnt; 
                SCpnt = SCpnt->next)
            {
                online_status = SDpnt->online;
                SDpnt->online = FALSE;
                save_flags(flags);
                cli();
                if(SCpnt->request.rq_status != RQ_INACTIVE) 
                {
                    restore_flags(flags);
                    printk("SCSI device not inactive - state=%d, id=%d\n",
                           SCpnt->request.rq_status, SCpnt->target);
                    for(SDpnt1 = shpnt->host_queue; SDpnt1; 
                        SDpnt1 = SDpnt1->next)
                      {
                        for(SCpnt = SDpnt1->device_queue; SCpnt; 
                            SCpnt = SCpnt->next)
                          if(SCpnt->request.rq_status == RQ_SCSI_DISCONNECTING)
                            SCpnt->request.rq_status = RQ_INACTIVE;
                      }
                    SDpnt->online = online_status;
                    printk("Device busy???\n");
                    return;
                }
                /*
                 * No, this device is really free.  Mark it as such, and
                 * continue on.
                 */
                SCpnt->state = SCSI_STATE_DISCONNECTING;
                SCpnt->request.rq_status = RQ_SCSI_DISCONNECTING;  /* Mark as busy */
                restore_flags(flags);
            }
        }
    }
    /* Next we detach the high level drivers from the Scsi_Device structures */

    for(shpnt = scsi_hostlist; shpnt; shpnt = shpnt->next)
    {
        if(shpnt->hostt != tpnt)
        {
            continue;
        }

        for(SDpnt = shpnt->host_queue; SDpnt; 
            SDpnt = SDpnt->next)
        {
            for(sdtpnt = scsi_devicelist; sdtpnt; sdtpnt = sdtpnt->next)
              if(sdtpnt->detach) (*sdtpnt->detach)(SDpnt);

            /* If something still attached, punt */
            if (SDpnt->attached) 
            {
                printk("Attached usage count = %d\n", SDpnt->attached);
                return;
            }
        }
    }

    /*
     * Next, kill the kernel error recovery thread for this host.
     */
    for(shpnt = scsi_hostlist; shpnt; shpnt = shpnt->next)
    {
        if(   shpnt->hostt == tpnt 
              && shpnt->hostt->use_new_eh_code
              && shpnt->ehandler != NULL )
        {
            struct semaphore sem = MUTEX_LOCKED;
            
            shpnt->eh_notify = &sem;
            send_sig(SIGKILL, shpnt->ehandler, 1);
            down(&sem);
            shpnt->eh_notify = NULL;
        }
    }

    /* Next we free up the Scsi_Cmnd structures for this host */

    for(shpnt = scsi_hostlist; shpnt; shpnt = shpnt->next)
    {
        if(shpnt->hostt != tpnt)
        {
            continue;
        }

        for(SDpnt = shpnt->host_queue; SDpnt; 
            SDpnt = shpnt->host_queue)
        {
            while (SDpnt->device_queue)
            {
                SCpnt = SDpnt->device_queue->next;
                scsi_init_free((char *) SDpnt->device_queue, sizeof(Scsi_Cmnd));
                SDpnt->device_queue = SCpnt;
            }
            SDpnt->has_cmdblocks = 0;

            /* Next free up the Scsi_Device structures for this host */
            shpnt->host_queue = SDpnt->next;
            scsi_init_free((char *) SDpnt, sizeof (Scsi_Device));

        }
    }

    /* Next we go through and remove the instances of the individual hosts
     * that were detected */

    for(shpnt = scsi_hostlist; shpnt; shpnt = sh1) 
    {
        sh1 = shpnt->next;
        if(shpnt->hostt == tpnt) {
            if(shpnt->loaded_as_module) {
                pcount = next_scsi_host;
                /* Remove the /proc/scsi directory entry */
#if CONFIG_PROC_FS
                proc_scsi_unregister(tpnt->proc_dir,
                                     shpnt->host_no + PROC_SCSI_FILE);
#endif
                if(tpnt->release)
                    (*tpnt->release)(shpnt);
                else {
                    /* This is the default case for the release function.
                     * It should do the right thing for most correctly
                     * written host adapters.
                     */
                    if (shpnt->irq) free_irq(shpnt->irq, NULL);
                    if (shpnt->dma_channel != 0xff) free_dma(shpnt->dma_channel);
                    if (shpnt->io_port && shpnt->n_io_port)
                        release_region(shpnt->io_port, shpnt->n_io_port);
                }
                if(pcount == next_scsi_host) scsi_unregister(shpnt);
                tpnt->present--;
            }
        }
    }

    /*
     * If there are absolutely no more hosts left, it is safe
     * to completely nuke the DMA pool.  The resize operation will
     * do the right thing and free everything.
     */
    if( !scsi_hosts )
        resize_dma_pool();

    printk ("scsi : %d host%s.\n", next_scsi_host,
            (next_scsi_host == 1) ? "" : "s");

#if defined(USE_STATIC_SCSI_MEMORY)
    printk ("SCSI memory: total %ldKb, used %ldKb, free %ldKb.\n",
            (scsi_memory_upper_value - scsi_memory_lower_value) / 1024,
            (scsi_init_memory_start - scsi_memory_lower_value) / 1024,
            (scsi_memory_upper_value - scsi_init_memory_start) / 1024);
#endif

    scsi_make_blocked_list();

    /* There were some hosts that were loaded at boot time, so we cannot
       do any more than this */
    if (tpnt->present) return;

    /* OK, this is the very last step.  Remove this host adapter from the
       linked list. */
    for(SHTp=NULL, SHT=scsi_hosts; SHT; SHTp=SHT, SHT=SHT->next)
        if(SHT == tpnt) {
            if(SHTp)
                SHTp->next = SHT->next;
            else
                scsi_hosts = SHT->next;
            SHT->next = NULL;
            break;
        }

    /* Rebuild the /proc/scsi directory entries */
#if CONFIG_PROC_FS
    proc_scsi_unregister(tpnt->proc_dir, tpnt->proc_dir->low_ino);
#endif
    MOD_DEC_USE_COUNT;
}

/*
 * This entry point should be called by a loadable module if it is trying
 * add a high level scsi driver to the system.
 */
static int scsi_register_device_module(struct Scsi_Device_Template * tpnt)
{
    Scsi_Device      * SDpnt;
    struct Scsi_Host * shpnt;

    if (tpnt->next) return 1;

    scsi_register_device(tpnt);
    /*
     * First scan the devices that we know about, and see if we notice them.
     */

    for(shpnt = scsi_hostlist; shpnt; shpnt = shpnt->next)
    {
        for(SDpnt = shpnt->host_queue; SDpnt; 
            SDpnt = SDpnt->next)
        {
            if(tpnt->detect) SDpnt->attached += (*tpnt->detect)(SDpnt);
        }
    }

    /*
     * If any of the devices would match this driver, then perform the
     * init function.
     */
    if(tpnt->init && tpnt->dev_noticed)
        if ((*tpnt->init)()) return 1;

    /*
     * Now actually connect the devices to the new driver.
     */
    for(shpnt = scsi_hostlist; shpnt; shpnt = shpnt->next)
    {
        for(SDpnt = shpnt->host_queue; SDpnt; 
            SDpnt = SDpnt->next)
        {
            if(tpnt->attach)  (*tpnt->attach)(SDpnt);
            /*
             * If this driver attached to the device, and don't have any
             * command blocks for this device, allocate some.
             */
            if(SDpnt->attached && SDpnt->has_cmdblocks == 0)
            {
                SDpnt->online = TRUE;
                scsi_build_commandblocks(SDpnt);
            }
        }
    }

    /*
     * This does any final handling that is required.
     */
    if(tpnt->finish && tpnt->nr_dev)  (*tpnt->finish)();
    resize_dma_pool();
    MOD_INC_USE_COUNT;
    return 0;
}

static int scsi_unregister_device(struct Scsi_Device_Template * tpnt)
{
    Scsi_Device * SDpnt;
    Scsi_Cmnd * SCpnt;
    struct Scsi_Host * shpnt;
    struct Scsi_Device_Template * spnt;
    struct Scsi_Device_Template * prev_spnt;

    /*
     * If we are busy, this is not going to fly.
     */
    if(tpnt->module->usecount != 0) return 0;

    /*
     * Next, detach the devices from the driver.
     */

    for(shpnt = scsi_hostlist; shpnt; shpnt = shpnt->next)
    {
        for(SDpnt = shpnt->host_queue; SDpnt; 
            SDpnt = SDpnt->next)
        {
            if(tpnt->detach) (*tpnt->detach)(SDpnt);
            if(SDpnt->attached == 0)
            {
                SDpnt->online = FALSE;

                /*
                 * Nobody is using this device any more.  Free all of the
                 * command structures.
                 */
                for(SCpnt = SDpnt->device_queue; SCpnt; 
                    SCpnt = SCpnt->next)
                {
                    if(SCpnt == SDpnt->device_queue)
                        SDpnt->device_queue = SCpnt->next;
                    scsi_init_free((char *) SCpnt, sizeof(*SCpnt));
                }
                SDpnt->has_cmdblocks = 0;
            }
        }
    }
    /*
     * Extract the template from the linked list.
     */
    spnt = scsi_devicelist;
    prev_spnt = NULL;
    while(spnt != tpnt)
    {
        prev_spnt = spnt;
        spnt = spnt->next;
    }
    if(prev_spnt == NULL)
        scsi_devicelist = tpnt->next;
    else
        prev_spnt->next = spnt->next;

    MOD_DEC_USE_COUNT;
    /*
     * Final cleanup for the driver is done in the driver sources in the
     * cleanup function.
     */
    return 0;
}


int scsi_register_module(int module_type, void * ptr)
{
    switch(module_type)
    {
    case MODULE_SCSI_HA:
        return scsi_register_host((Scsi_Host_Template *) ptr);
        
        /* Load upper level device handler of some kind */
    case MODULE_SCSI_DEV:
#ifdef CONFIG_KERNELD
        if (scsi_hosts == NULL)
            request_module("scsi_hostadapter");
#endif
        return scsi_register_device_module((struct Scsi_Device_Template *) ptr);
        /* The rest of these are not yet implemented */
        
        /* Load constants.o */
    case MODULE_SCSI_CONST:
        
        /* Load specialized ioctl handler for some device.  Intended for
         * cdroms that have non-SCSI2 audio command sets. */
    case MODULE_SCSI_IOCTL:
        
    default:
        return 1;
    }
}

void scsi_unregister_module(int module_type, void * ptr)
{
    switch(module_type) 
    {
    case MODULE_SCSI_HA:
        scsi_unregister_host((Scsi_Host_Template *) ptr);
        break;
    case MODULE_SCSI_DEV:
        scsi_unregister_device((struct Scsi_Device_Template *) ptr);
        break;
        /* The rest of these are not yet implemented. */
    case MODULE_SCSI_CONST:
    case MODULE_SCSI_IOCTL:
        break;
    default:
    }
    return;
}

#endif          /* CONFIG_MODULES */

/*
 * Function:    scsi_dump_status
 *
 * Purpose:     Brain dump of scsi system, used for problem solving.
 *
 * Arguments:   level - used to indicate level of detail.
 *
 * Notes:       The level isn't used at all yet, but we need to find some way
 *              of sensibly logging varying degrees of information.  A quick one-line
 *              display of each command, plus the status would be most useful.
 *
 *              This does depend upon CONFIG_SCSI_LOGGING - I do want some way of turning
 *              it all off if the user wants a lean and mean kernel.  It would probably
 *              also be useful to allow the user to specify one single host to be dumped.
 *              A second argument to the function would be useful for that purpose.
 *
 *              FIXME - some formatting of the output into tables would be very handy.
 */
static void
scsi_dump_status(int level)
{
#if CONFIG_PROC_FS
#if CONFIG_SCSI_LOGGING /* { */
    int i;
    struct Scsi_Host * shpnt;
    Scsi_Cmnd * SCpnt;
    Scsi_Device * SDpnt;
    printk("Dump of scsi host parameters:\n");
    i = 0;
    for(shpnt = scsi_hostlist; shpnt; shpnt = shpnt->next)
    {
        printk(" %d %d %d : %d %p\n",
               shpnt->host_failed,
               shpnt->host_busy,
               atomic_read(&shpnt->host_active),
               shpnt->host_blocked,
               shpnt->pending_commands);

    }

    printk("\n\n");
    printk("Dump of scsi command parameters:\n");
    for(shpnt = scsi_hostlist; shpnt; shpnt = shpnt->next)
    {
        printk("h:c:t:l (dev sect nsect cnumsec sg) (ret all flg) (to/cmd to ito) cmd snse result\n");
        for(SDpnt=shpnt->host_queue; SDpnt; SDpnt = SDpnt->next)
        {
            for(SCpnt=SDpnt->device_queue; SCpnt; SCpnt = SCpnt->next)
            {
                /*  (0) h:c:t:l (dev sect nsect cnumsec sg) (ret all flg) (to/cmd to ito) cmd snse result %d %x      */
                printk("(%3d) %2d:%1d:%2d:%2d (%6s %4ld %4ld %4ld %4x %1d) (%1d %1d 0x%2x) (%4d %4d %4d) 0x%2.2x 0x%2.2x 0x%8.8x\n",
                       i++, 

                       SCpnt->host->host_no,
                       SCpnt->channel,
                       SCpnt->target,
                       SCpnt->lun,

                       kdevname(SCpnt->request.rq_dev),
                       SCpnt->request.sector,
                       SCpnt->request.nr_sectors,
                       SCpnt->request.current_nr_sectors,
                       SCpnt->request.rq_status,
                       SCpnt->use_sg,

                       SCpnt->retries,
                       SCpnt->allowed,
                       SCpnt->flags,

                       SCpnt->timeout_per_command,
                       SCpnt->timeout,
                       SCpnt->internal_timeout,

                       SCpnt->cmnd[0],
                       SCpnt->sense_buffer[2],
                       SCpnt->result);
            }
        }
    }

    for(shpnt = scsi_hostlist; shpnt; shpnt = shpnt->next)
    {
        for(SDpnt=shpnt->host_queue; SDpnt; SDpnt = SDpnt->next)
        {
            /* Now dump the request lists for each block device */
            printk("Dump of pending block device requests\n");
            for(i=0; i<MAX_BLKDEV; i++)
            {
                if(blk_dev[i].current_request)
                {
                    struct request * req;
                    printk("%d: ", i);
                    req = blk_dev[i].current_request;
                    while(req) 
                    {
                        printk("(%s %d %ld %ld %ld) ",
                               kdevname(req->rq_dev),
                               req->cmd,
                               req->sector,
                               req->nr_sectors,
                               req->current_nr_sectors);
                        req = req->next;
                    }
                    printk("\n");
                }
            }
        }
    }
    printk("wait_for_request = %p\n", wait_for_request);
#endif /* CONFIG_SCSI_LOGGING */ /* } */
#endif /* CONFIG_PROC_FS */
}

#ifdef MODULE

int init_module(void) 
{
    unsigned long size;

    /*
     * This makes /proc/scsi visible.
     */
#if CONFIG_PROC_FS
    dispatch_scsi_info_ptr = dispatch_scsi_info;
#endif

    scsi_loadable_module_flag = 1;

    /* Register the /proc/scsi/scsi entry */
#if CONFIG_PROC_FS
    proc_scsi_register(0, &proc_scsi_scsi);
#endif


    dma_sectors = PAGE_SIZE / SECTOR_SIZE;
    scsi_dma_free_sectors= dma_sectors;
    /*
     * Set up a minimal DMA buffer list - this will be used during scan_scsis
     * in some cases.
     */

    /* One bit per sector to indicate free/busy */
    size = (dma_sectors / SECTORS_PER_PAGE)*sizeof(FreeSectorBitmap);
    dma_malloc_freelist = (unsigned char *) scsi_init_malloc(size, GFP_ATOMIC);
    memset(dma_malloc_freelist, 0, size);

    /* One pointer per page for the page list */
    dma_malloc_pages = (unsigned char **)
        scsi_init_malloc((dma_sectors / SECTORS_PER_PAGE)*sizeof(*dma_malloc_pages), GFP_ATOMIC);
    dma_malloc_pages[0] = (unsigned char *)
        scsi_init_malloc(PAGE_SIZE, GFP_ATOMIC | GFP_DMA);

    /*
     * This is where the processing takes place for most everything
     * when commands are completed.
     */
    init_bh(SCSI_BH, scsi_bottom_half_handler);

    return 0;
}

void cleanup_module( void)
{
    remove_bh(SCSI_BH);

#if CONFIG_PROC_FS
    proc_scsi_unregister(0, PROC_SCSI_SCSI);

    /* No, we're not here anymore. Don't show the /proc/scsi files. */
    dispatch_scsi_info_ptr = 0L;
#endif

    /*
     * Free up the DMA pool.
     */
    resize_dma_pool();

}
#endif /* MODULE */

/*
 * Overrides for Emacs so that we follow Linus's tabbing style.
 * Emacs will notice this stuff at the end of the file and automatically
 * adjust the settings for this buffer only.  This must remain at the end
 * of the file.
 * ---------------------------------------------------------------------------
 * Local variables:
 * c-indent-level: 4
 * c-brace-imaginary-offset: 0
 * c-brace-offset: -4
 * c-argdecl-indent: 4
 * c-label-offset: -4
 * c-continued-statement-offset: 4
 * c-continued-brace-offset: 0
 * indent-tabs-mode: nil
 * tab-width: 8
 * End:
 */