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@aib.com 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>
 */

/*
 * Don't import our own symbols, as this would severely mess up our
 * symbol tables.
 */
#define _SCSI_SYMS_VER_

#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>

#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 $";
*/


/* 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 };

#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

static void scsi_done (Scsi_Cmnd *SCpnt);
int update_timeout (Scsi_Cmnd *, int);
static void print_inquiry(unsigned char *data);
static 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);

static FreeSectorBitmap * dma_malloc_freelist = NULL;
static int scsi_need_isa_bounce_buffers;
static unsigned int dma_sectors = 0;
unsigned int dma_free_sectors = 0;
unsigned int need_isa_buffer = 0;
static unsigned char ** dma_malloc_pages = NULL;

static int time_start;
static int time_elapsed;
static volatile struct Scsi_Host * host_active = NULL;
#define SCSI_BLOCK(HOST) ((HOST->block && host_active && HOST != host_active) \
			  || (HOST->can_queue && HOST->host_busy >= HOST->can_queue))

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   "
};


/*
 * global variables :
 * scsi_devices an array of these specifying the address for each
 * (host, id, LUN)
 */

Scsi_Device * scsi_devices = NULL;

/* Process ID of SCSI commands */
unsigned long scsi_pid = 0;

static unsigned long serial_number = 0;

static unsigned char generic_sense[6] = {REQUEST_SENSE, 0,0,0, 255, 0};
static void resize_dma_pool(void);

/* This variable is merely a hook so that we can debug the kernel with gdb. */
Scsi_Cmnd * last_cmnd = NULL;

/* This is the pointer to the /proc/scsi code.
 * It is only initialized to !=0 if the scsi code is present
 */
#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);

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

/*
 *  This is the number  of clock ticks we should wait before we time out
 *  and abort the command.  This is for  where the scsi.c module generates
 *  the command, not where it originates from a higher level, in which
 *  case the timeout is specified there.
 *
 *  ABORT_TIMEOUT and RESET_TIMEOUT are the timeouts for RESET and ABORT
 *  respectively.
 */

#ifdef DEBUG_TIMEOUT
static void scsi_dump_status(void);
#endif


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

#ifdef DEBUG
    #define SENSE_TIMEOUT SCSI_TIMEOUT
    #define ABORT_TIMEOUT SCSI_TIMEOUT
    #define RESET_TIMEOUT SCSI_TIMEOUT
#else
    #define SENSE_TIMEOUT (5*HZ/10)
    #define RESET_TIMEOUT (5*HZ/10)
    #define ABORT_TIMEOUT (5*HZ/10)
#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

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},
{"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;
}

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)
{

#ifdef DEBUG
    printk ("scan_scsis_done(%p, %06x)\n", SCpnt->host, SCpnt->result);
#endif
    SCpnt->request.rq_status = RQ_SCSI_DONE;

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

#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 dev, lun, channel;
  unsigned char scsi_result0[256];
  unsigned char *scsi_result;
  Scsi_Device *SDpnt;
  int max_dev_lun, sparse_lun;
  Scsi_Cmnd *SCpnt;

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


  /* 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 */
  if(shpnt->host_queue)
      shpnt->host_queue->prev = SCpnt;
  SCpnt->next = shpnt->host_queue;
  SCpnt->prev = NULL;
  shpnt->host_queue = SCpnt;


  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 */

  leave:

  {/* Unchain SCpnt from host_queue */
    Scsi_Cmnd *prev, *next, *hqptr;
    for(hqptr = shpnt->host_queue; hqptr != SCpnt; hqptr = hqptr->next) ;
    if(hqptr) {
      prev = hqptr->prev;
      next = hqptr->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);

}

/*
 * 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;

  SDtail = scsi_devices;
  if (scsi_devices)
    while (SDtail->next)
      SDtail = SDtail->next;

  memset (SDpnt, 0, sizeof (Scsi_Device));
  SDpnt->host = shpnt;
  SDpnt->id = dev;
  SDpnt->lun = lun;
  SDpnt->channel = channel;

  /* 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);
  }

#if defined(DEBUG) || defined(DEBUG_INIT)
  printk ("scsi: scan_scsis_single id %d lun %d. Return code 0x%08x\n",
          dev, lun, SCpnt->result);
  print_driverbyte(SCpnt->result); print_hostbyte(SCpnt->result);
  printk("\n");
#endif

  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;
  }

#if defined (DEBUG) || defined(DEBUG_INIT)
  printk ("scsi: performing INQUIRY\n");
#endif
  /*
   * 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);
  }

#if defined(DEBUG) || defined(DEBUG_INIT)
  printk ("scsi: INQUIRY %s with code 0x%x\n",
          SCpnt->result ? "failed" : "successful", SCpnt->result);
#endif

  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->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->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;

  /*
   * 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);
    }
  }
  /* Add this device to the linked list at the end */
  if (SDtail)
    SDtail->next = SDpnt;
  else
    scsi_devices = SDpnt;
  SDtail = SDpnt;

  SDpnt = (Scsi_Device *) scsi_init_malloc (sizeof (Scsi_Device), GFP_ATOMIC);
  *SDpnt2=SDpnt;
  if (!SDpnt)
    printk ("scsi: scan_scsis_single: Cannot malloc\n");


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

  /*
   * 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;

  /*
   * 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 is our time out function, called when the timer expires for a
 * given host adapter.  It will attempt to abort the currently executing
 * command, that failing perform a kernel panic.
 */

static void scsi_times_out (Scsi_Cmnd * SCpnt)
{

    switch (SCpnt->internal_timeout & (IN_ABORT | IN_RESET | IN_RESET2 | IN_RESET3))
    {
    case NORMAL_TIMEOUT:
	{
#ifdef DEBUG_TIMEOUT
	    scsi_dump_status();
#endif
	}

	if (!scsi_abort (SCpnt, DID_TIME_OUT))
	    return;
    case IN_ABORT:
	printk("SCSI host %d abort (pid %ld) timed out - resetting\n",
	       SCpnt->host->host_no, SCpnt->pid);
	if (!scsi_reset (SCpnt, SCSI_RESET_ASYNCHRONOUS))
	    return;
    case IN_RESET:
    case (IN_ABORT | IN_RESET):
	/* This might be controversial, but if there is a bus hang,
	 * you might conceivably want the machine up and running
	 * esp if you have an ide disk.
	 */
	printk("SCSI host %d channel %d reset (pid %ld) timed out - "
               "trying harder\n",
	       SCpnt->host->host_no, SCpnt->channel, SCpnt->pid);
	SCpnt->internal_timeout &= ~IN_RESET;
	SCpnt->internal_timeout |= IN_RESET2;
        scsi_reset (SCpnt,
		    SCSI_RESET_ASYNCHRONOUS | SCSI_RESET_SUGGEST_BUS_RESET);
        return;
    case (IN_ABORT | IN_RESET | IN_RESET2):
	/* Obviously the bus reset didn't work.
	 * Let's try even harder and call for an HBA reset.
         * Maybe the HBA itself crashed and this will shake it loose.
	 */
	printk("SCSI host %d reset (pid %ld) timed out - trying to shake it loose\n",
	       SCpnt->host->host_no, SCpnt->pid);
	SCpnt->internal_timeout &= ~(IN_RESET | IN_RESET2);
	SCpnt->internal_timeout |= IN_RESET3;
        scsi_reset (SCpnt,
		    SCSI_RESET_ASYNCHRONOUS | SCSI_RESET_SUGGEST_HOST_RESET);
	return;

    default:
	printk("SCSI host %d reset (pid %ld) timed out again -\n",
	       SCpnt->host->host_no, SCpnt->pid);
	printk("probably an unrecoverable SCSI bus or device hang.\n");
	return;

    }

}


/* 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 * 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 request_queueable().\n");

    if (req && req->rq_status == RQ_INACTIVE)
	panic("Inactive in 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->device_next;
	}
    } else {
	SCpnt = device->host->host_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->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 */
    }

    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;

    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
 * request_queueable function also knows the internal allocation scheme
 * of the packets for each device
 */

Scsi_Cmnd * 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 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(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->device_next;
	    }
	} else {
	    SCpnt = device->host->host_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 1	/* NEW CODE */
		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 allocate_device\n");
	 		}
 		}
#else	/* ORIGINAL CODE */
		    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 allocate_device\n");
		    }
		    SCSI_SLEEP(&device->device_wait,
			       (SCwait->request.rq_status != RQ_INACTIVE));
#endif
	} 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 */
	    }
	    restore_flags(flags);
	    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.
     */
    SCpnt->channel = device->channel;
    SCpnt->lun = device->lun;
    SCpnt->target = device->id;

    return SCpnt;
}

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

inline void internal_cmnd (Scsi_Cmnd * SCpnt)
{
    unsigned long flags, timeout;
    struct Scsi_Host * host;
#ifdef DEBUG_DELAY
    unsigned long clock;
#endif

#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);

    update_timeout(SCpnt, SCpnt->timeout_per_command);

    /*
     * We will use a queued command if possible, otherwise we will emulate the
     * queuing and calling of completion function ourselves.
     */
#ifdef DEBUG
    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);
#endif

    if (host->can_queue)
    {
#ifdef DEBUG
	printk("queuecommand : routine at %p\n",
	       host->hostt->queuecommand);
#endif
	/* 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);

	host->hostt->queuecommand (SCpnt, scsi_done);

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

#ifdef DEBUG
	printk("command() :  routine at %p\n", host->hostt->command);
#endif
	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
	scsi_done(SCpnt);
    }
#ifdef DEBUG
    printk("leaving internal_cmnd()\n");
#endif
}

static void scsi_request_sense (Scsi_Cmnd * SCpnt)
{
    unsigned long flags;

    save_flags(flags);
    cli();
    SCpnt->flags |= WAS_SENSE | ASKED_FOR_SENSE;
    update_timeout(SCpnt, SENSE_TIMEOUT);
    restore_flags(flags);


    memcpy ((void *) SCpnt->cmnd , (void *) generic_sense,
	    sizeof(generic_sense));

    SCpnt->cmnd[1] = SCpnt->lun << 5;
    SCpnt->cmnd[4] = sizeof(SCpnt->sense_buffer);

    SCpnt->request_buffer = &SCpnt->sense_buffer;
    SCpnt->request_bufflen = sizeof(SCpnt->sense_buffer);
    SCpnt->use_sg = 0;
    SCpnt->cmd_len = COMMAND_SIZE(SCpnt->cmnd[0]);
    internal_cmnd (SCpnt);
}



/*
 * 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;

#ifdef DEBUG
    {
	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");
    }
#endif

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

    if (host->block) host_active = host;

    host->host_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);
#if 0
    SCpnt->host = host;
    SCpnt->channel = channel;
    SCpnt->target = target;
    SCpnt->lun = (SCpnt->data_cmnd[1] >> 5);
#endif
    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);

#ifdef DEBUG
    printk ("Leaving scsi_do_cmd()\n");
#endif
}

static int check_sense (Scsi_Cmnd * SCpnt)
{
    /* If there is no sense information, request it.  If we have already
     * requested it, there is no point in asking again - the firmware must
     * be confused.
     */
    if (((SCpnt->sense_buffer[0] & 0x70) >> 4) != 7) {
	if(!(SCpnt->flags & ASKED_FOR_SENSE))
	    return SUGGEST_SENSE;
	else
	    return SUGGEST_RETRY;
    }

    SCpnt->flags &= ~ASKED_FOR_SENSE;

#ifdef DEBUG_INIT
    printk("scsi%d, channel%d : ", SCpnt->host->host_no, SCpnt->channel);
    print_sense("", SCpnt);
    printk("\n");
#endif
    if (SCpnt->sense_buffer[2] & 0xe0)
	return SUGGEST_ABORT;

    switch (SCpnt->sense_buffer[2] & 0xf)
    {
    case NO_SENSE:
	return 0;
    case RECOVERED_ERROR:
	return SUGGEST_IS_OK;

    case ABORTED_COMMAND:
	return SUGGEST_RETRY;
    case NOT_READY:
    case UNIT_ATTENTION:
        /*
         * If we are expecting a CC/UA because of a bus reset that we
         * performed, treat this just as a retry.  Otherwise this is
         * information that we should pass up to the upper-level driver
         * so that we can deal with it there.
         */
        if( SCpnt->device->expecting_cc_ua )
        {
            SCpnt->device->expecting_cc_ua = 0;
            return SUGGEST_RETRY;
        }
	return SUGGEST_ABORT;

    /* these three are not supported */
    case COPY_ABORTED:
    case VOLUME_OVERFLOW:
    case MISCOMPARE:

    case MEDIUM_ERROR:
	return SUGGEST_REMAP;
    case BLANK_CHECK:
    case DATA_PROTECT:
    case HARDWARE_ERROR:
    case ILLEGAL_REQUEST:
    default:
	return SUGGEST_ABORT;
    }
}

/* 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) Call last_cmnd[host].done.  This is done for fatal errors and
 *      normal completion, and indicates that the handling for this
 *      request is complete.
 *  (2) Call internal_cmnd to requeue the command.  This will result in
 *      scsi_done being called again when the retry is complete.
 *  (3) Call scsi_request_sense.  This asks the host adapter/drive for
 *      more information about the error condition.  When the information
 *      is available, scsi_done will be called again.
 *  (4) Call reset().  This is sort of a last resort, and the idea is that
 *      this may kick things loose and get the drive working again.  reset()
 *      automatically calls scsi_request_sense, and thus scsi_done will be
 *      called again once the reset is complete.
 *
 *      If none of the above actions are taken, the drive in question
 *      will hang. If more than one of the above actions are taken by
 *      scsi_done, then unpredictable behavior will result.
 */
static void scsi_done (Scsi_Cmnd * SCpnt)
{
    int status=0;
    int exit=0;
    int checked;
    int oldto;
    struct Scsi_Host * host = SCpnt->host;
    int result = SCpnt->result;
    SCpnt->serial_number = 0;
    oldto = update_timeout(SCpnt, 0);

#ifdef DEBUG_TIMEOUT
    if(result) printk("Non-zero result in scsi_done %x %d:%d\n",
		      result, SCpnt->target, SCpnt->lun);
#endif

    /* If we requested an abort, (and we got it) then fix up the return
     *  status to say why
     */
    if(host_byte(result) == DID_ABORT && SCpnt->abort_reason)
	SCpnt->result = result = (result & 0xff00ffff) |
	    (SCpnt->abort_reason << 16);


#define FINISHED 0
#define MAYREDO  1
#define REDO     3
#define PENDING  4

#ifdef DEBUG
    printk("In scsi_done(host = %d, result = %06x)\n", host->host_no, result);
#endif

    if(SCpnt->flags & WAS_SENSE)
    {
	SCpnt->use_sg = SCpnt->old_use_sg;
	SCpnt->cmd_len = SCpnt->old_cmd_len;
    }

    switch (host_byte(result))
    {
    case DID_OK:
	if (status_byte(result) && (SCpnt->flags & WAS_SENSE))
	    /* Failed to obtain sense information */
	{
	    SCpnt->flags &= ~WAS_SENSE;
#if 0	/* This cannot possibly be correct. */
	    SCpnt->internal_timeout &= ~SENSE_TIMEOUT;
#endif

	    if (!(SCpnt->flags & WAS_RESET))
	    {
		printk("scsi%d : channel %d target %d lun %d request sense"
		       " failed, performing reset.\n",
		       SCpnt->host->host_no, SCpnt->channel, SCpnt->target,
		       SCpnt->lun);
		scsi_reset(SCpnt, SCSI_RESET_SYNCHRONOUS);
		return;
	    }
	    else
	    {
		exit = (DRIVER_HARD | SUGGEST_ABORT);
		status = FINISHED;
	    }
	}
	else switch(msg_byte(result))
	{
	case COMMAND_COMPLETE:
	    switch (status_byte(result))
	    {
	    case GOOD:
		if (SCpnt->flags & WAS_SENSE)
		{
#ifdef DEBUG
		    printk ("In scsi_done, GOOD status, COMMAND COMPLETE, "
                            "parsing sense information.\n");
#endif
		    SCpnt->flags &= ~WAS_SENSE;
#if 0	/* This cannot possibly be correct. */
		    SCpnt->internal_timeout &= ~SENSE_TIMEOUT;
#endif

		    switch (checked = check_sense(SCpnt))
		    {
		    case SUGGEST_SENSE:
		    case 0:
#ifdef DEBUG
			printk("NO SENSE.  status = REDO\n");
#endif
			update_timeout(SCpnt, oldto);
			status = REDO;
			break;
		    case SUGGEST_IS_OK:
			break;
		    case SUGGEST_REMAP:
#ifdef DEBUG
			printk("SENSE SUGGEST REMAP - status = FINISHED\n");
#endif
			status = FINISHED;
			exit = DRIVER_SENSE | SUGGEST_ABORT;
			break;
		    case SUGGEST_RETRY:
#ifdef DEBUG
			printk("SENSE SUGGEST RETRY - status = MAYREDO\n");
#endif
			status = MAYREDO;
			exit = DRIVER_SENSE | SUGGEST_RETRY;
			break;
		    case SUGGEST_ABORT:
#ifdef DEBUG
			printk("SENSE SUGGEST ABORT - status = FINISHED");
#endif
			status = FINISHED;
			exit =  DRIVER_SENSE | SUGGEST_ABORT;
			break;
		    default:
			printk ("Internal error %s %d \n", __FILE__,
				__LINE__);
		    }
		} /* end WAS_SENSE */
		else
		{
#ifdef DEBUG
		    printk("COMMAND COMPLETE message returned, "
                           "status = FINISHED. \n");
#endif
		    exit =  DRIVER_OK;
		    status = FINISHED;
		}
		break;

	    case CHECK_CONDITION:
	    case COMMAND_TERMINATED:
		switch (check_sense(SCpnt))
		{
		case 0:
		    update_timeout(SCpnt, oldto);
		    status = REDO;
		    break;
		case SUGGEST_REMAP:
		    status = FINISHED;
		    exit =  DRIVER_SENSE | SUGGEST_ABORT;
		    break;
		case SUGGEST_RETRY:
		    status = MAYREDO;
		    exit = DRIVER_SENSE | SUGGEST_RETRY;
		    break;
		case SUGGEST_ABORT:
		    status = FINISHED;
		    exit =  DRIVER_SENSE | SUGGEST_ABORT;
		    break;
		case SUGGEST_SENSE:
		    scsi_request_sense (SCpnt);
		    status = PENDING;
		    break;
		}
		break;

	    case CONDITION_GOOD:
	    case INTERMEDIATE_GOOD:
	    case INTERMEDIATE_C_GOOD:
		break;

	    case BUSY:
	    case QUEUE_FULL:
		update_timeout(SCpnt, oldto);
		status = REDO;
		break;

	    case RESERVATION_CONFLICT:
		printk("scsi%d, channel %d : RESERVATION CONFLICT performing"
		       " reset.\n", SCpnt->host->host_no, SCpnt->channel);
		scsi_reset(SCpnt, SCSI_RESET_SYNCHRONOUS);
		return;
#if 0
		exit = DRIVER_SOFT | SUGGEST_ABORT;
		status = MAYREDO;
		break;
#endif
	    default:
		printk ("Internal error %s %d \n"
			"status byte = %d \n", __FILE__,
			__LINE__, status_byte(result));

	    }
	    break;
	default:
	    panic("scsi: unsupported message byte %d received\n",
		  msg_byte(result));
	}
	break;
    case DID_TIME_OUT:
#ifdef DEBUG
	printk("Host returned DID_TIME_OUT - ");
#endif

	if (SCpnt->flags & WAS_TIMEDOUT)
	{
#ifdef DEBUG
	    printk("Aborting\n");
#endif
	    /*
	      Allow TEST_UNIT_READY and INQUIRY commands to timeout early
	      without causing resets.  All other commands should be retried.
	    */
	    if (SCpnt->cmnd[0] != TEST_UNIT_READY &&
		SCpnt->cmnd[0] != INQUIRY)
		    status = MAYREDO;
	    exit = (DRIVER_TIMEOUT | SUGGEST_ABORT);
	}
	else
	{
#ifdef DEBUG
	    printk ("Retrying.\n");
#endif
	    SCpnt->flags  |= WAS_TIMEDOUT;
	    SCpnt->internal_timeout &= ~IN_ABORT;
	    status = REDO;
	}
	break;
    case DID_BUS_BUSY:
    case DID_PARITY:
	status = REDO;
	break;
    case DID_NO_CONNECT:
#ifdef DEBUG
	printk("Couldn't connect.\n");
#endif
	exit  = (DRIVER_HARD | SUGGEST_ABORT);
	break;
    case DID_ERROR:
	status = MAYREDO;
	exit = (DRIVER_HARD | SUGGEST_ABORT);
	break;
    case DID_BAD_TARGET:
    case DID_ABORT:
	exit = (DRIVER_INVALID | SUGGEST_ABORT);
	break;
    case DID_RESET:
	if (SCpnt->flags & IS_RESETTING)
	{
	    SCpnt->flags &= ~IS_RESETTING;
	    status = REDO;
	    break;
	}

	if(msg_byte(result) == GOOD &&
	   status_byte(result) == CHECK_CONDITION) {
	    switch (check_sense(SCpnt)) {
	    case 0:
		update_timeout(SCpnt, oldto);
		status = REDO;
		break;
	    case SUGGEST_REMAP:
	    case SUGGEST_RETRY:
		status = MAYREDO;
		exit = DRIVER_SENSE | SUGGEST_RETRY;
		break;
	    case SUGGEST_ABORT:
		status = FINISHED;
		exit =  DRIVER_SENSE | SUGGEST_ABORT;
		break;
	    case SUGGEST_SENSE:
		scsi_request_sense (SCpnt);
		status = PENDING;
		break;
	    }
	} else {
	    status=REDO;
	    exit = SUGGEST_RETRY;
	}
	break;
    default :
	exit = (DRIVER_ERROR | SUGGEST_DIE);
    }

    switch (status)
    {
    case FINISHED:
    case PENDING:
	break;
    case MAYREDO:
#ifdef DEBUG
	printk("In MAYREDO, allowing %d retries, have %d\n",
	       SCpnt->allowed, SCpnt->retries);
#endif
	if ((++SCpnt->retries) < SCpnt->allowed)
	{
	    if ((SCpnt->retries >= (SCpnt->allowed >> 1))
		&& !(SCpnt->host->last_reset > 0 &&
		     jiffies < SCpnt->host->last_reset + MIN_RESET_PERIOD)
		&& !(SCpnt->flags & WAS_RESET))
	    {
		printk("scsi%d channel %d : resetting for second half of retries.\n",
		       SCpnt->host->host_no, SCpnt->channel);
		scsi_reset(SCpnt, SCSI_RESET_SYNCHRONOUS);
		break;
	    }

	}
	else
	{
	    status = FINISHED;
	    break;
	}
	/* fall through to REDO */

    case REDO:

	if (SCpnt->flags & WAS_SENSE)
	    scsi_request_sense(SCpnt);
	else
	{
	    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;
	    internal_cmnd (SCpnt);
	}
	break;
    default:
	INTERNAL_ERROR;
    }

    if (status == FINISHED) {
#ifdef DEBUG
	printk("Calling done function - at address %p\n", SCpnt->done);
#endif
	host->host_busy--; /* Indicate that we are free */

	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);
	    }

	}

	wake_up(&host->host_wait);
	SCpnt->result = result | ((exit & 0xff) << 24);
	SCpnt->use_sg = SCpnt->old_use_sg;
	SCpnt->cmd_len = SCpnt->old_cmd_len;
	SCpnt->done (SCpnt);
    }

#undef FINISHED
#undef REDO
#undef MAYREDO
#undef PENDING
}

/*
 * The scsi_abort function interfaces with the abort() function of the host
 * we are aborting, and causes the current command to not complete.  The
 * caller should deal with any error messages or status returned on the
 * next call.
 *
 * This will not be called reentrantly for a given host.
 */

/*
 * Since we're nice guys and specified that abort() and reset()
 * can be non-reentrant.  The internal_timeout flags are used for
 * this.
 */


int scsi_abort (Scsi_Cmnd * SCpnt, int why)
{
    int oldto;
    unsigned long flags;
    struct Scsi_Host * host = SCpnt->host;

    while(1)
    {
	save_flags(flags);
	cli();

	/*
	 * Protect against races here.  If the command is done, or we are
	 * on a different command forget it.
	 */
	if (SCpnt->serial_number != SCpnt->serial_number_at_timeout) {
	    restore_flags(flags);
	    return 0;
	}

	if (SCpnt->internal_timeout & IN_ABORT)
	{
	    restore_flags(flags);
	    while (SCpnt->internal_timeout & IN_ABORT)
		barrier();
	}
	else
	{
	    SCpnt->internal_timeout |= IN_ABORT;
	    oldto = update_timeout(SCpnt, ABORT_TIMEOUT);

	    if ((SCpnt->flags & IS_RESETTING) && SCpnt->device->soft_reset) {
		/* OK, this command must have died when we did the
		 *  reset.  The device itself must have lied.
		 */
		printk("Stale command on %d %d:%d appears to have died when"
		       " the bus was reset\n",
		       SCpnt->channel, SCpnt->target, SCpnt->lun);
	    }

	    restore_flags(flags);
	    if (!host->host_busy) {
		SCpnt->internal_timeout &= ~IN_ABORT;
		update_timeout(SCpnt, oldto);
		return 0;
	    }
	    printk("scsi : aborting command due to timeout : pid %lu, scsi%d,"
		   " channel %d, id %d, lun %d ",
		   SCpnt->pid, SCpnt->host->host_no, (int) SCpnt->channel,
		   (int) SCpnt->target, (int) SCpnt->lun);
	    print_command (SCpnt->cmnd);
	    if (SCpnt->serial_number != SCpnt->serial_number_at_timeout)
		return 0;
	    SCpnt->abort_reason = why;
	    switch(host->hostt->abort(SCpnt)) {
		/* We do not know how to abort.  Try waiting another
		 * time increment and see if this helps. Set the
		 * WAS_TIMEDOUT flag set so we do not try this twice
		 */
	    case SCSI_ABORT_BUSY: /* Tough call - returning 1 from
				   * this is too severe
				   */
	    case SCSI_ABORT_SNOOZE:
		if(why == DID_TIME_OUT) {
		    save_flags(flags);
		    cli();
		    SCpnt->internal_timeout &= ~IN_ABORT;
		    if(SCpnt->flags & WAS_TIMEDOUT) {
			restore_flags(flags);
			return 1; /* Indicate we cannot handle this.
				   * We drop down into the reset handler
				   * and try again
				   */
		    } else {
			SCpnt->flags |= WAS_TIMEDOUT;
			oldto = SCpnt->timeout_per_command;
			update_timeout(SCpnt, oldto);
		    }
		    restore_flags(flags);
		}
		return 0;
	    case SCSI_ABORT_PENDING:
		if(why != DID_TIME_OUT) {
		    save_flags(flags);
		    cli();
		    update_timeout(SCpnt, oldto);
		    restore_flags(flags);
		}
		return 0;
	    case SCSI_ABORT_SUCCESS:
		/* We should have already aborted this one.  No
		 * need to adjust timeout
		 */
                 SCpnt->internal_timeout &= ~IN_ABORT;
                 return 0;
	    case SCSI_ABORT_NOT_RUNNING:
		SCpnt->internal_timeout &= ~IN_ABORT;
		update_timeout(SCpnt, 0);
		return 0;
	    case SCSI_ABORT_ERROR:
	    default:
		SCpnt->internal_timeout &= ~IN_ABORT;
		return 1;
	    }
	}
    }
}


/* Mark a single SCSI Device as having been reset. */

static inline void scsi_mark_device_reset(Scsi_Device *Device)
{
  Device->was_reset = 1;
  Device->expecting_cc_ua = 1;
}


/* Mark all SCSI Devices on a specific Host as having been reset. */

void scsi_mark_host_reset(struct Scsi_Host *Host)
{
  Scsi_Cmnd *SCpnt;
  for (SCpnt = Host->host_queue; SCpnt; SCpnt = SCpnt->next)
      scsi_mark_device_reset(SCpnt->device);
}


/* Mark all SCSI Devices on a specific Host Bus as having been reset. */

void scsi_mark_bus_reset(struct Scsi_Host *Host, int channel)
{
  Scsi_Cmnd *SCpnt;
  for (SCpnt = Host->host_queue; SCpnt; SCpnt = SCpnt->next)
      if (SCpnt->channel == channel)
	  scsi_mark_device_reset(SCpnt->device);
}


int scsi_reset (Scsi_Cmnd * SCpnt, unsigned int reset_flags)
{
    int temp;
    unsigned long flags;
    Scsi_Cmnd * SCpnt1;
    struct Scsi_Host * host = SCpnt->host;

    printk("SCSI bus is being reset for host %d channel %d.\n",
	   host->host_no, SCpnt->channel);

#if 0
    /*
     * First of all, we need to make a recommendation to the low-level
     * driver as to whether a BUS_DEVICE_RESET should be performed,
     * or whether we should do a full BUS_RESET.  There is no simple
     * algorithm here - we basically use a series of heuristics
     * to determine what we should do.
     */
    SCpnt->host->suggest_bus_reset = FALSE;

    /*
     * First see if all of the active devices on the bus have
     * been jammed up so that we are attempting resets.  If so,
     * then suggest a bus reset.  Forcing a bus reset could
     * result in some race conditions, but no more than
     * you would usually get with timeouts.  We will cross
     * that bridge when we come to it.
     *
     * This is actually a pretty bad idea, since a sequence of
     * commands will often timeout together and this will cause a
     * Bus Device Reset followed immediately by a SCSI Bus Reset.
     * If all of the active devices really are jammed up, the
     * Bus Device Reset will quickly timeout and scsi_times_out
     * will follow up with a SCSI Bus Reset anyway.
     */
    SCpnt1 = host->host_queue;
    while(SCpnt1) {
	if( SCpnt1->request.rq_status != RQ_INACTIVE
	    && (SCpnt1->flags & (WAS_RESET | IS_RESETTING)) == 0 )
            	break;
        SCpnt1 = SCpnt1->next;
 	}
    if( SCpnt1 == NULL ) {
        reset_flags |= SCSI_RESET_SUGGEST_BUS_RESET;
    }

    /*
     * If the code that called us is suggesting a hard reset, then
     * definitely request it.  This usually occurs because a
     * BUS_DEVICE_RESET times out.
     *
     * Passing reset_flags along takes care of this automatically.
     */
    if( reset_flags & SCSI_RESET_SUGGEST_BUS_RESET ) {
        SCpnt->host->suggest_bus_reset = TRUE;
    }
#endif

    while (1) {
	save_flags(flags);
	cli();

	/*
	 * Protect against races here.  If the command is done, or we are
	 * on a different command forget it.
	 */
	if (reset_flags & SCSI_RESET_ASYNCHRONOUS)
	  if (SCpnt->serial_number != SCpnt->serial_number_at_timeout) {
	    restore_flags(flags);
	    return 0;
	  }

	if (SCpnt->internal_timeout & IN_RESET)
	{
	    restore_flags(flags);
	    while (SCpnt->internal_timeout & IN_RESET)
		barrier();
	}
	else
	{
	    SCpnt->internal_timeout |= IN_RESET;
	    update_timeout(SCpnt, RESET_TIMEOUT);

	    if (host->host_busy)
	    {
		restore_flags(flags);
		SCpnt1 = host->host_queue;
		while(SCpnt1) {
		    if (SCpnt1->request.rq_status != RQ_INACTIVE) {
#if 0
			if (!(SCpnt1->flags & IS_RESETTING) &&
			    !(SCpnt1->internal_timeout & IN_ABORT))
			    scsi_abort(SCpnt1, DID_RESET);
#endif
			SCpnt1->flags |= (WAS_RESET | IS_RESETTING);
		    }
		    SCpnt1 = SCpnt1->next;
		}

		host->last_reset = jiffies;
		temp = host->hostt->reset(SCpnt, reset_flags);
		/*
		  This test allows the driver to introduce an additional bus
		  settle time delay by setting last_reset up to 20 seconds in
		  the future.  In the normal case where the driver does not
		  modify last_reset, it must be assumed that the actual bus
		  reset occurred immediately prior to the return to this code,
		  and so last_reset must be updated to the current time, so
		  that the delay in internal_cmnd will guarantee at least a
		  MIN_RESET_DELAY bus settle time.
		*/
		if (host->last_reset - jiffies > 20UL * HZ)
		  host->last_reset = jiffies;
	    }
	    else
	    {
		if (!host->block) host->host_busy++;
		restore_flags(flags);
		host->last_reset = jiffies;
	        SCpnt->flags |= (WAS_RESET | IS_RESETTING);
		temp = host->hostt->reset(SCpnt, reset_flags);
		if ((host->last_reset < jiffies) ||
		    (host->last_reset > (jiffies + 20 * HZ)))
		  host->last_reset = jiffies;
		if (!host->block) host->host_busy--;
	    }

#ifdef DEBUG
	    printk("scsi reset function returned %d\n", temp);
#endif

            /*
             * Now figure out what we need to do, based upon
             * what the low level driver said that it did.
	     * If the result is SCSI_RESET_SUCCESS, SCSI_RESET_PENDING,
	     * or SCSI_RESET_WAKEUP, then the low level driver did a
	     * bus device reset or bus reset, so we should go through
	     * and mark one or all of the devices on that bus
	     * as having been reset.
             */
            switch(temp & SCSI_RESET_ACTION) {
	    case SCSI_RESET_SUCCESS:
	        if (temp & SCSI_RESET_HOST_RESET)
		  scsi_mark_host_reset(host);
	        else if (temp & SCSI_RESET_BUS_RESET)
		  scsi_mark_bus_reset(host, SCpnt->channel);
		else scsi_mark_device_reset(SCpnt->device);
		save_flags(flags);
		cli();
		SCpnt->internal_timeout &= ~(IN_RESET|IN_RESET2|IN_RESET3);
		restore_flags(flags);
		return 0;
	    case SCSI_RESET_PENDING:
	        if (temp & SCSI_RESET_HOST_RESET)
		  scsi_mark_host_reset(host);
	        else if (temp & SCSI_RESET_BUS_RESET)
		  scsi_mark_bus_reset(host, SCpnt->channel);
		else scsi_mark_device_reset(SCpnt->device);
	    case SCSI_RESET_NOT_RUNNING:
		return 0;
	    case SCSI_RESET_PUNT:
		SCpnt->internal_timeout &= ~(IN_RESET|IN_RESET2|IN_RESET3);
                scsi_request_sense (SCpnt);
                return 0;
	    case SCSI_RESET_WAKEUP:
	        if (temp & SCSI_RESET_HOST_RESET)
		  scsi_mark_host_reset(host);
	        else if (temp & SCSI_RESET_BUS_RESET)
		  scsi_mark_bus_reset(host, SCpnt->channel);
		else scsi_mark_device_reset(SCpnt->device);
		SCpnt->internal_timeout &= ~(IN_RESET|IN_RESET2|IN_RESET3);
		scsi_request_sense (SCpnt);
                /*
                 * If a bus reset was performed, we
                 * need to wake up each and every command
                 * that was active on the bus or if it was a HBA
                 * reset all active commands on all channels
                 */
                if( temp & SCSI_RESET_HOST_RESET )
                {
		    SCpnt1 = host->host_queue;
		    while(SCpnt1) {
			if (SCpnt1->request.rq_status != RQ_INACTIVE
			    && SCpnt1 != SCpnt)
			    scsi_request_sense (SCpnt1);
			SCpnt1 = SCpnt1->next;
                    }
                } else if( temp & SCSI_RESET_BUS_RESET ) {
                    SCpnt1 = host->host_queue;
                    while(SCpnt1) {
                        if(SCpnt1->request.rq_status != RQ_INACTIVE
                           && SCpnt1 != SCpnt
                           && SCpnt1->channel == SCpnt->channel)
                            scsi_request_sense (SCpnt);
                        SCpnt1 = SCpnt1->next;
                    }
                }
		return 0;
	    case SCSI_RESET_SNOOZE:
		/* In this case, we set the timeout field to 0
		 * so that this command does not time out any more,
		 * and we return 1 so that we get a message on the
		 * screen.
		 */
		save_flags(flags);
		cli();
		SCpnt->internal_timeout &= ~(IN_RESET|IN_RESET2|IN_RESET3);
		update_timeout(SCpnt, 0);
		restore_flags(flags);
		/* If you snooze, you lose... */
	    case SCSI_RESET_ERROR:
	    default:
		return 1;
	    }

	    return temp;
	}
    }
}


static void scsi_main_timeout(void)
{
    /*
     * We must not enter update_timeout with a timeout condition still pending.
     */

    int timed_out;
    unsigned long flags;
    struct Scsi_Host * host;
    Scsi_Cmnd * SCpnt = NULL;

    save_flags(flags);
    cli();

    update_timeout(NULL, 0);

    /*
     * Find all timers such that they have 0 or negative (shouldn't happen)
     * time remaining on them.
     */
    timed_out = 0;
    for (host = scsi_hostlist; host; host = host->next) {
	for (SCpnt = host->host_queue; SCpnt; SCpnt = SCpnt->next)
	    if (SCpnt->timeout == -1)
	      {
		SCpnt->timeout = 0;
		SCpnt->serial_number_at_timeout = SCpnt->serial_number;
		++timed_out;
	      }
    }
    if (timed_out > 0) {
	for (host = scsi_hostlist; host; host = host->next) {
	    for (SCpnt = host->host_queue; SCpnt; SCpnt = SCpnt->next)
		if (SCpnt->serial_number_at_timeout > 0 &&
		    SCpnt->serial_number_at_timeout == SCpnt->serial_number)
		  {
		    restore_flags(flags);
		    scsi_times_out(SCpnt);
		    SCpnt->serial_number_at_timeout = 0;
		    cli();
		  }
	  }
    }
    restore_flags(flags);
}

/*
 * The strategy is to cause the timer code to call scsi_times_out()
 * when the soonest timeout is pending.
 * The arguments are used when we are queueing a new command, because
 * we do not want to subtract the time used from this time, but when we
 * set the timer, we want to take this value into account.
 */

int update_timeout(Scsi_Cmnd * SCset, int timeout)
{
    unsigned int least, used;
    unsigned int oldto;
    unsigned long flags;
    struct Scsi_Host * host;
    Scsi_Cmnd * SCpnt = NULL;

    save_flags(flags);
    cli();

    oldto = 0;

    /*
     * This routine can be a performance bottleneck under high loads, since
     * it is called twice per SCSI operation: once when internal_cmnd is
     * called, and again when scsi_done completes the command.  To limit
     * the load this routine can cause, we shortcut processing if no clock
     * ticks have occurred since the last time it was called.
     */

    if (jiffies == time_start && timer_table[SCSI_TIMER].expires > 0) {
	if(SCset){
	    oldto = SCset->timeout;
	    SCset->timeout = timeout;
	    if (timeout > 0 &&
		jiffies + timeout < timer_table[SCSI_TIMER].expires)
		    timer_table[SCSI_TIMER].expires = jiffies + timeout;
	}
	restore_flags(flags);
	return oldto;
    }

    /*
     * Figure out how much time has passed since the last time the timeouts
     * were updated
     */
    used = (time_start) ? (jiffies - time_start) : 0;

    /*
     * Find out what is due to timeout soonest, and adjust all timeouts for
     * the amount of time that has passed since the last time we called
     * update_timeout.
     */

    oldto = 0;

    if(SCset){
	oldto = SCset->timeout - used;
	SCset->timeout = timeout;
    }

    least = 0xffffffff;

    for(host = scsi_hostlist; host; host = host->next)
	for(SCpnt = host->host_queue; SCpnt; SCpnt = SCpnt->next)
	    if (SCpnt->timeout > 0) {
	        if (SCpnt != SCset)
		    SCpnt->timeout -= used;
		if(SCpnt->timeout <= 0) SCpnt->timeout = -1;
		if(SCpnt->timeout > 0 && SCpnt->timeout < least)
		    least = SCpnt->timeout;
	    }

    /*
     * If something is due to timeout again, then we will set the next timeout
     * interrupt to occur.  Otherwise, timeouts are disabled.
     */

    if (least != 0xffffffff)
    {
	time_start = jiffies;
	timer_table[SCSI_TIMER].expires = (time_elapsed = least) + jiffies;
	timer_active |= 1 << SCSI_TIMER;
    }
    else
    {
	timer_table[SCSI_TIMER].expires = time_start = time_elapsed = 0;
	timer_active &= ~(1 << SCSI_TIMER);
    }
    restore_flags(flags);
    return oldto;
}

#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);
		dma_free_sectors -= nbits;
#ifdef DEBUG
		printk("SMalloc: %d %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);
#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");
            }
            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 priority)
{
    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_dma_pages(priority & GFP_LEVEL_MASK,
	                                            order);
    } else
        retval = kmalloc(size, priority);

    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));
	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->use_sg = 0;
	SCpnt->old_use_sg = 0;
	SCpnt->old_cmd_len = 0;
	SCpnt->timeout = 0;
	SCpnt->underflow = 0;
	SCpnt->transfersize = 0;
	SCpnt->serial_number = 0;
	SCpnt->serial_number_at_timeout = 0;
	SCpnt->host_scribble = NULL;
	if(host->host_queue)
	    host->host_queue->prev = SCpnt;
	SCpnt->next = host->host_queue;
	SCpnt->prev = NULL;
	host->host_queue = SCpnt;
	SCpnt->device_next = SDpnt->device_queue;
	SDpnt->device_queue = SCpnt;
    }
    SDpnt->has_cmdblocks = 1;
}

/*
 * scsi_dev_init() is our initialization routine, which in turn calls host
 * initialization, bus scanning, and sd/st initialization routines.
 */

__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;

    timer_table[SCSI_TIMER].fn = scsi_main_timeout;
    timer_table[SCSI_TIMER].expires = 0;

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

    /* initialize all hosts */
    scsi_init();

    scsi_devices = (Scsi_Device *) NULL;

    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, scsi_devices);
    }

    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 (SDpnt=scsi_devices; 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;
}

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, *scd_h = NULL;
    struct Scsi_Host *HBA_ptr;
    char *p;
    int   host, channel, id, lun;
    int	  size, len = 0;
    off_t begin = 0;
    off_t pos = 0;

    scd = scsi_devices;
    HBA_ptr = scsi_hostlist;

    if(inout == 0) {
	size = sprintf(buffer+len,"Attached devices: %s\n", (scd)?"":"none");
	len += size;
	pos = begin + len;
	while (HBA_ptr) {
#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
	    scd = scsi_devices;
	    while (scd) {
		if (scd->host == HBA_ptr) {
		    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;
		}
		scd = scd->next;
	    }
	    HBA_ptr = HBA_ptr->next;
	}

    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 < 25 || strncmp("scsi", buffer, 4))
	return(-EINVAL);

    /*
     * 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);

	while(scd && (scd->host->host_no != host
	      || scd->channel != channel
	      || scd->id != id
	      || scd->lun != lun)) {
	    scd = scd->next;
	}
	if(scd)
	    return(-ENOSYS);  /* We do not yet support unplugging */
	while(HBA_ptr && HBA_ptr->host_no != host)
	    HBA_ptr = HBA_ptr->next;

	if(!HBA_ptr)
	    return(-ENXIO);

	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);

        while(scd != NULL) {
            if(scd->host->host_no == host
               && scd->channel == channel
               && scd->id == id
               && scd->lun == lun){
                break;
            }
            scd_h = scd;
            scd = scd->next;
        }

        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->host->host_queue; SCpnt; SCpnt = SCpnt->next){
                if(SCpnt->device == scd) {
                    if(SCpnt->prev != NULL)
                        SCpnt->prev->next = SCpnt->next;
                    if(SCpnt->next != NULL)
                        SCpnt->next->prev = SCpnt->prev;
                    if(SCpnt == scd->host->host_queue)
                        scd->host->host_queue = SCpnt->next;
                    scsi_init_free((char *) SCpnt, sizeof(*SCpnt));
                }
            }
            /* Now we can remove the device structure */
            if(scd_h != NULL) {
                scd_h->next = scd->next;
            } else if (scsi_devices == scd) {
                /* We had a hit on the first entry of the device list */
                scsi_devices = 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_devices )
    {
	/*
	 * Free up the DMA pool.
	 */
	if( dma_free_sectors != dma_sectors )
	    panic("SCSI DMA pool memory leak %d %d\n",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;
	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)
	scsi_need_isa_bounce_buffers = 1;
    else
	scsi_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 (SDpnt=scsi_devices; SDpnt; SDpnt = SDpnt->next) {
	host = SDpnt->host;

	/*
	 * 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 &&
	   scsi_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);
    }

    dma_free_sectors += new_dma_sectors - dma_sectors;
    dma_malloc_pages = new_dma_malloc_pages;
    dma_sectors = new_dma_sectors;
    need_isa_buffer = new_need_isa_buffer;
    restore_flags(flags);

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

	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, scsi_devices);
	    }

	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(SDpnt = scsi_devices; 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.
 */
static void scsi_unregister_host(Scsi_Host_Template * tpnt)
{
    Scsi_Host_Template * SHT, *SHTp;
    Scsi_Device *sdpnt, * sdppnt, * sdpnt1;
    Scsi_Cmnd * SCpnt;
    unsigned long flags;
    struct Scsi_Device_Template * sdtpnt;
    struct Scsi_Host * shpnt, *sh1;
    int pcount;

    /* First verify that this host adapter is completely free with no pending
     * commands */

    for(sdpnt = scsi_devices; sdpnt; sdpnt = sdpnt->next)
	if(sdpnt->host->hostt == tpnt && sdpnt->host->hostt->module
	   && sdpnt->host->hostt->module->usecount) return;

    for(shpnt = scsi_hostlist; shpnt; shpnt = shpnt->next)
    {
	if (shpnt->hostt != tpnt) continue;
	for(SCpnt = shpnt->host_queue; SCpnt; SCpnt = SCpnt->next)
	{
	    save_flags(flags);
	    cli();
	    if(SCpnt->request.rq_status != RQ_INACTIVE) {
		restore_flags(flags);
		for(SCpnt = shpnt->host_queue; SCpnt; SCpnt = SCpnt->next)
		    if(SCpnt->request.rq_status == RQ_SCSI_DISCONNECTING)
			SCpnt->request.rq_status = RQ_INACTIVE;
		printk("Device busy???\n");
		return;
	    }
	    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(sdpnt = scsi_devices; sdpnt; sdpnt = sdpnt->next)
	if(sdpnt->host->hostt == tpnt)
	{
	    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 we free up the Scsi_Cmnd structures for this host */

    for(sdpnt = scsi_devices; sdpnt; sdpnt = sdpnt->next)
	if(sdpnt->host->hostt == tpnt)
	    while (sdpnt->host->host_queue) {
		SCpnt = sdpnt->host->host_queue->next;
		scsi_init_free((char *) sdpnt->host->host_queue, sizeof(Scsi_Cmnd));
		sdpnt->host->host_queue = SCpnt;
		if (SCpnt) SCpnt->prev = NULL;
		sdpnt->has_cmdblocks = 0;
	    }

    /* Next free up the Scsi_Device structures for this host */

    sdppnt = NULL;
    for(sdpnt = scsi_devices; sdpnt; sdpnt = sdpnt1)
    {
	sdpnt1 = sdpnt->next;
	if (sdpnt->host->hostt == tpnt) {
	    if (sdppnt)
		sdppnt->next = sdpnt->next;
	    else
		scsi_devices = sdpnt->next;
	    scsi_init_free((char *) sdpnt, sizeof (Scsi_Device));
	} else
	    sdppnt = sdpnt;
    }

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

    shpnt = scsi_hostlist;
    while(shpnt) {
	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--;
	    }
	}
	shpnt = sh1;
    }

    /*
     * 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_devices )
	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;

    if (tpnt->next) return 1;

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

    for(SDpnt = scsi_devices; 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(SDpnt = scsi_devices; SDpnt; SDpnt = SDpnt->next)
    {
	if(tpnt->attach)  (*tpnt->attach)(SDpnt);
	/*
	 * If this driver attached to the device, and we no longer
	 * have anything attached, release the scsi command blocks.
	 */
	if(SDpnt->attached && SDpnt->has_cmdblocks == 0)
	    scsi_build_commandblocks(SDpnt);
    }

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

static int scsi_unregister_device(struct Scsi_Device_Template * tpnt)
{
    Scsi_Device * SDpnt;
    Scsi_Cmnd * SCpnt;
    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(SDpnt = scsi_devices; SDpnt; SDpnt = SDpnt->next)
    {
	if(tpnt->detach) (*tpnt->detach)(SDpnt);
	if(SDpnt->attached == 0)
	{
	    /*
	     * Nobody is using this device any more.  Free all of the
	     * command structures.
	     */
	    for(SCpnt = SDpnt->host->host_queue; SCpnt; SCpnt = SCpnt->next)
	    {
		if(SCpnt->device == SDpnt)
		{
		    if(SCpnt->prev != NULL)
			SCpnt->prev->next = SCpnt->next;
		    if(SCpnt->next != NULL)
			SCpnt->next->prev = SCpnt->prev;
		    if(SCpnt == SDpnt->host->host_queue)
			SDpnt->host->host_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 */

#ifdef DEBUG_TIMEOUT
static void
scsi_dump_status(void)
{
    int i;
    struct Scsi_Host * shpnt;
    Scsi_Cmnd * SCpnt;
    printk("Dump of scsi parameters:\n");
    i = 0;
    for(shpnt = scsi_hostlist; shpnt; shpnt = shpnt->next)
	for(SCpnt=shpnt->host_queue; SCpnt; SCpnt = SCpnt->next)
	{
	    /*  (0) 0:0:0:0 (802 123434 8 8 0) (3 3 2) (%d %d %d) %d %x      */
	    printk("(%d) %d:%d:%d:%d (%s %ld %ld %ld %d) (%d %d %x) (%d %d %d) %x %x %x\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->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);
	}
    printk("wait_for_request = %p\n", wait_for_request);
    /* 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");
	}
}
#endif

#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

    timer_table[SCSI_TIMER].fn = scsi_main_timeout;
    timer_table[SCSI_TIMER].expires = 0;
    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;
    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);
    return 0;
}

void cleanup_module( void)
{
#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();

    timer_table[SCSI_TIMER].fn = NULL;
    timer_table[SCSI_TIMER].expires = 0;
}
#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:
 */