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scsi_sa.c

/*-
 * Implementation of SCSI Sequential Access Peripheral driver for CAM.
 *
 * Copyright (c) 1999, 2000 Matthew Jacob
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions, and the following disclaimer,
 *    without modification, immediately at the beginning of the file.
 * 2. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD: src/sys/cam/scsi/scsi_sa.c,v 1.105.2.1 2006/01/26 04:57:04 mjacob Exp $");

#include <sys/param.h>
#include <sys/queue.h>
#ifdef _KERNEL
#include <sys/systm.h>
#include <sys/kernel.h>
#endif
#include <sys/types.h>
#include <sys/time.h>
#include <sys/bio.h>
#include <sys/limits.h>
#include <sys/malloc.h>
#include <sys/mtio.h>
#ifdef _KERNEL
#include <sys/conf.h>
#endif
#include <sys/fcntl.h>
#include <sys/devicestat.h>

#ifndef _KERNEL
#include <stdio.h>
#include <string.h>
#endif

#include <cam/cam.h>
#include <cam/cam_ccb.h>
#include <cam/cam_periph.h>
#include <cam/cam_xpt_periph.h>
#include <cam/cam_debug.h>

#include <cam/scsi/scsi_all.h>
#include <cam/scsi/scsi_message.h>
#include <cam/scsi/scsi_sa.h>

#ifdef _KERNEL

#include <opt_sa.h>

#ifndef SA_IO_TIMEOUT
#define SA_IO_TIMEOUT         4
#endif
#ifndef SA_SPACE_TIMEOUT
#define SA_SPACE_TIMEOUT      1 * 60
#endif
#ifndef SA_REWIND_TIMEOUT
#define SA_REWIND_TIMEOUT     2 * 60
#endif
#ifndef SA_ERASE_TIMEOUT
#define SA_ERASE_TIMEOUT      4 * 60
#endif

#define     SCSIOP_TIMEOUT          (60 * 1000) /* not an option */

#define     IO_TIMEOUT        (SA_IO_TIMEOUT * 60 * 1000)
#define     REWIND_TIMEOUT          (SA_REWIND_TIMEOUT * 60 * 1000)
#define     ERASE_TIMEOUT           (SA_ERASE_TIMEOUT * 60 * 1000)
#define     SPACE_TIMEOUT           (SA_SPACE_TIMEOUT * 60 * 1000)

/*
 * Additional options that can be set for config: SA_1FM_AT_EOT
 */

#ifndef     UNUSED_PARAMETER
#define     UNUSED_PARAMETER(x)     x = x
#endif

#define     QFRLS(ccb)  \
      if (((ccb)->ccb_h.status & CAM_DEV_QFRZN) != 0) \
            cam_release_devq((ccb)->ccb_h.path, 0, 0, 0, FALSE)

/*
 * Driver states
 */

MALLOC_DEFINE(M_SCSISA, "SCSI sa", "SCSI sequential access buffers");

typedef enum {
      SA_STATE_NORMAL, SA_STATE_ABNORMAL
} sa_state;

#define ccb_pflags      ppriv_field0
#define ccb_bp          ppriv_ptr1

#define     SA_CCB_BUFFER_IO  0x0
#define     SA_CCB_WAITING          0x1
#define     SA_CCB_TYPEMASK         0x1
#define     SA_POSITION_UPDATED     0x2

#define     Set_CCB_Type(x, type)                     \
      x->ccb_h.ccb_pflags &= ~SA_CCB_TYPEMASK;  \
      x->ccb_h.ccb_pflags |= type

#define     CCB_Type(x) (x->ccb_h.ccb_pflags & SA_CCB_TYPEMASK)



typedef enum {
      SA_FLAG_OPEN            = 0x0001,
      SA_FLAG_FIXED           = 0x0002,
      SA_FLAG_TAPE_LOCKED     = 0x0004,
      SA_FLAG_TAPE_MOUNTED    = 0x0008,
      SA_FLAG_TAPE_WP         = 0x0010,
      SA_FLAG_TAPE_WRITTEN    = 0x0020,
      SA_FLAG_EOM_PENDING     = 0x0040,
      SA_FLAG_EIO_PENDING     = 0x0080,
      SA_FLAG_EOF_PENDING     = 0x0100,
      SA_FLAG_ERR_PENDING     = (SA_FLAG_EOM_PENDING|SA_FLAG_EIO_PENDING|
                           SA_FLAG_EOF_PENDING),
      SA_FLAG_INVALID         = 0x0200,
      SA_FLAG_COMP_ENABLED    = 0x0400,
      SA_FLAG_COMP_SUPP = 0x0800,
      SA_FLAG_COMP_UNSUPP     = 0x1000,
      SA_FLAG_TAPE_FROZEN     = 0x2000
} sa_flags;

typedef enum {
      SA_MODE_REWIND          = 0x00,
      SA_MODE_NOREWIND  = 0x01,
      SA_MODE_OFFLINE         = 0x02
} sa_mode;

typedef enum {
      SA_PARAM_NONE           = 0x00,
      SA_PARAM_BLOCKSIZE      = 0x01,
      SA_PARAM_DENSITY  = 0x02,
      SA_PARAM_COMPRESSION    = 0x04,
      SA_PARAM_BUFF_MODE      = 0x08,
      SA_PARAM_NUMBLOCKS      = 0x10,
      SA_PARAM_WP       = 0x20,
      SA_PARAM_SPEED          = 0x40,
      SA_PARAM_ALL            = 0x7f
} sa_params;

typedef enum {
      SA_QUIRK_NONE           = 0x00,
      SA_QUIRK_NOCOMP         = 0x01,     /* Can't deal with compression at all */
      SA_QUIRK_FIXED          = 0x02,     /* Force fixed mode */
      SA_QUIRK_VARIABLE = 0x04,     /* Force variable mode */
      SA_QUIRK_2FM            = 0x08,     /* Needs Two File Marks at EOD */
      SA_QUIRK_1FM            = 0x10,     /* No more than 1 File Mark at EOD */
      SA_QUIRK_NODREAD  = 0x20,     /* Don't try and dummy read density */
      SA_QUIRK_NO_MODESEL     = 0x40,     /* Don't do mode select at all */
      SA_QUIRK_NO_CPAGE = 0x80      /* Don't use DEVICE COMPRESSION page */
} sa_quirks;

/* units are bits 4-7, 16-21 (1024 units) */
#define SAUNIT(DEV) \
      (((minor(DEV) & 0xF0) >> 4) |  ((minor(DEV) & 0x3f0000) >> 16))

#define SAMODE(z) ((minor(z) & 0x3))
#define SADENSITY(z) (((minor(z) >> 2) & 0x3))
#define     SA_IS_CTRL(z) (minor(z) & (1 << 29))

#define SA_NOT_CTLDEV   0
#define SA_CTLDEV 1

#define SA_ATYPE_R      0
#define SA_ATYPE_NR     1
#define SA_ATYPE_ER     2

#define SAMINOR(ctl, unit, mode, access) \
      ((ctl << 29) | ((unit & 0x3f0) << 16) | ((unit & 0xf) << 4) | \
      (mode << 0x2) | (access & 0x3))

#define SA_NUM_MODES    4
struct sa_devs {
      struct cdev *ctl_dev;
      struct sa_mode_devs {
            struct cdev *r_dev;
            struct cdev *nr_dev;
            struct cdev *er_dev;
      } mode_devs[SA_NUM_MODES];
};

struct sa_softc {
      sa_state    state;
      sa_flags    flags;
      sa_quirks   quirks;
      struct            bio_queue_head bio_queue;
      int         queue_count;
      struct            devstat *device_stats;
      struct sa_devs    devs;
      int         blk_gran;
      int         blk_mask;
      int         blk_shift;
      u_int32_t   max_blk;
      u_int32_t   min_blk;
      u_int32_t   comp_algorithm;
      u_int32_t   saved_comp_algorithm;
      u_int32_t   media_blksize;
      u_int32_t   last_media_blksize;
      u_int32_t   media_numblks;
      u_int8_t    media_density;
      u_int8_t    speed;
      u_int8_t    scsi_rev;
      u_int8_t    dsreg;            /* mtio mt_dsreg, redux */
      int         buffer_mode;
      int         filemarks;
      union       ccb saved_ccb;
      int         last_resid_was_io;

      /*
       * Relative to BOT Location.
       */
      daddr_t           fileno;
      daddr_t           blkno;

      /*
       * Latched Error Info
       */
      struct {
            struct scsi_sense_data _last_io_sense;
            u_int32_t _last_io_resid;
            u_int8_t _last_io_cdb[CAM_MAX_CDBLEN];
            struct scsi_sense_data _last_ctl_sense;
            u_int32_t _last_ctl_resid;
            u_int8_t _last_ctl_cdb[CAM_MAX_CDBLEN];
#define     last_io_sense     errinfo._last_io_sense
#define     last_io_resid     errinfo._last_io_resid
#define     last_io_cdb errinfo._last_io_cdb
#define     last_ctl_sense    errinfo._last_ctl_sense
#define     last_ctl_resid    errinfo._last_ctl_resid
#define     last_ctl_cdb      errinfo._last_ctl_cdb
      } errinfo;
      /*
       * Misc other flags/state
       */
      u_int32_t
                              : 29,
            open_rdonly       : 1,  /* open read-only */
            open_pending_mount      : 1,  /* open pending mount */
            ctrl_mode         : 1;  /* control device open */
};

struct sa_quirk_entry {
      struct scsi_inquiry_pattern inq_pat;      /* matching pattern */
      sa_quirks quirks; /* specific quirk type */
      u_int32_t prefblk;      /* preferred blocksize when in fixed mode */
};

static struct sa_quirk_entry sa_quirk_table[] =
{
      {
            { T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "OnStream",
              "ADR*", "*"}, SA_QUIRK_FIXED|SA_QUIRK_NODREAD |
               SA_QUIRK_1FM|SA_QUIRK_NO_MODESEL, 32768
      },
      {
            { T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "ARCHIVE",
              "Python 06408*", "*"}, SA_QUIRK_NODREAD, 0
      },
      {
            { T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "ARCHIVE",
              "Python 25601*", "*"}, SA_QUIRK_NOCOMP|SA_QUIRK_NODREAD, 0
      },
      {
            { T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "ARCHIVE",
              "Python*", "*"}, SA_QUIRK_NODREAD, 0
      },
      {
            { T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "ARCHIVE",
              "VIPER 150*", "*"}, SA_QUIRK_FIXED|SA_QUIRK_1FM, 512
      },
      {
            { T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "ARCHIVE",
              "VIPER 2525 25462", "-011"},
              SA_QUIRK_NOCOMP|SA_QUIRK_1FM|SA_QUIRK_NODREAD, 0
      },
      {
            { T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "ARCHIVE",
              "VIPER 2525*", "*"}, SA_QUIRK_FIXED|SA_QUIRK_1FM, 1024
      },
#if   0
      {
            { T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "HP",
              "C15*", "*"}, SA_QUIRK_VARIABLE|SA_QUIRK_NO_CPAGE, 0,
      },
#endif
      {
            { T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "HP",
              "C56*", "*"}, SA_QUIRK_VARIABLE|SA_QUIRK_2FM, 0
      },
      {
            { T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "HP",
              "T20*", "*"}, SA_QUIRK_FIXED|SA_QUIRK_1FM, 512
      },
      {
            { T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "HP",
              "T4000*", "*"}, SA_QUIRK_FIXED|SA_QUIRK_1FM, 512
      },
      {
            { T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "HP",
              "HP-88780*", "*"}, SA_QUIRK_VARIABLE|SA_QUIRK_2FM, 0
      },
      {
            { T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "KENNEDY",
              "*", "*"}, SA_QUIRK_VARIABLE|SA_QUIRK_2FM, 0
      },
      {
            { T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "M4 DATA",
              "123107 SCSI*", "*"}, SA_QUIRK_VARIABLE|SA_QUIRK_2FM, 0
      },
      {     /* jreynold@primenet.com */
            { T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "Seagate",
            "STT8000N*", "*"}, SA_QUIRK_1FM, 0
      },
      {     /* mike@sentex.net */
            { T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "Seagate",
            "STT20000*", "*"}, SA_QUIRK_1FM, 0
      },
      {
            { T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "TANDBERG",
              " TDC 3600", "U07:"}, SA_QUIRK_NOCOMP|SA_QUIRK_1FM, 512
      },
      {
            { T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "TANDBERG",
              " TDC 3800", "*"}, SA_QUIRK_NOCOMP|SA_QUIRK_1FM, 512
      },
      {
            { T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "TANDBERG",
              " TDC 4100", "*"}, SA_QUIRK_NOCOMP|SA_QUIRK_1FM, 512
      },
      {
            { T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "TANDBERG",
              " TDC 4200", "*"}, SA_QUIRK_NOCOMP|SA_QUIRK_1FM, 512
      },
      {
            { T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "TANDBERG",
              " SLR*", "*"}, SA_QUIRK_1FM, 0
      },
      {
            { T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "WANGTEK",
              "5525ES*", "*"}, SA_QUIRK_FIXED|SA_QUIRK_1FM, 512
      },
      {
            { T_SEQUENTIAL, SIP_MEDIA_REMOVABLE, "WANGTEK",
              "51000*", "*"}, SA_QUIRK_FIXED|SA_QUIRK_1FM, 1024
      }
};

static      d_open_t    saopen;
static      d_close_t   saclose;
static      d_strategy_t      sastrategy;
static      d_ioctl_t   saioctl;
static      periph_init_t     sainit;
static      periph_ctor_t     saregister;
static      periph_oninv_t    saoninvalidate;
static      periph_dtor_t     sacleanup;
static      periph_start_t    sastart;
static      void        saasync(void *callback_arg, u_int32_t code,
                        struct cam_path *path, void *arg);
static      void        sadone(struct cam_periph *periph,
                         union ccb *start_ccb);
static  int       saerror(union ccb *ccb, u_int32_t cam_flags,
                        u_int32_t sense_flags);
static int        samarkswanted(struct cam_periph *);
static int        sacheckeod(struct cam_periph *periph);
static int        sagetparams(struct cam_periph *periph,
                            sa_params params_to_get,
                            u_int32_t *blocksize, u_int8_t *density,
                            u_int32_t *numblocks, int *buff_mode,
                            u_int8_t *write_protect, u_int8_t *speed,
                            int *comp_supported, int *comp_enabled,
                            u_int32_t *comp_algorithm,
                            sa_comp_t *comp_page);
static int        sasetparams(struct cam_periph *periph,
                            sa_params params_to_set,
                            u_int32_t blocksize, u_int8_t density,
                            u_int32_t comp_algorithm,
                            u_int32_t sense_flags);
static void       saprevent(struct cam_periph *periph, int action);
static int        sarewind(struct cam_periph *periph);
static int        saspace(struct cam_periph *periph, int count,
                        scsi_space_code code);
static int        samount(struct cam_periph *, int, struct cdev *);
static int        saretension(struct cam_periph *periph);
static int        sareservereleaseunit(struct cam_periph *periph,
                                   int reserve);
static int        saloadunload(struct cam_periph *periph, int load);
static int        saerase(struct cam_periph *periph, int longerase);
static int        sawritefilemarks(struct cam_periph *periph,
                               int nmarks, int setmarks);
static int        sardpos(struct cam_periph *periph, int, u_int32_t *);
static int        sasetpos(struct cam_periph *periph, int, u_int32_t *);


static struct periph_driver sadriver =
{
      sainit, "sa",
      TAILQ_HEAD_INITIALIZER(sadriver.units), /* generation */ 0
};

PERIPHDRIVER_DECLARE(sa, sadriver);

/* For 2.2-stable support */
#ifndef D_TAPE
#define D_TAPE 0
#endif


static struct cdevsw sa_cdevsw = {
      .d_version =      D_VERSION,
      .d_open =   saopen,
      .d_close =  saclose,
      .d_read =   physread,
      .d_write =  physwrite,
      .d_ioctl =  saioctl,
      .d_strategy =     sastrategy,
      .d_name =   "sa",
      .d_flags =  D_TAPE | D_NEEDGIANT,
};

static int
saopen(struct cdev *dev, int flags, int fmt, struct thread *td)
{
      struct cam_periph *periph;
      struct sa_softc *softc;
      int unit;
      int error;
      int s;

      unit = SAUNIT(dev);

      s = splsoftcam();
      periph = (struct cam_periph *)dev->si_drv1;
      if (periph == NULL) {
            (void) splx(s);
            return (ENXIO);   
      }
      softc = (struct sa_softc *)periph->softc;
      if ((error = cam_periph_lock(periph, PRIBIO|PCATCH)) != 0) {
            splx(s);
            return (error);
      }
      splx(s);

      CAM_DEBUG(periph->path, CAM_DEBUG_TRACE|CAM_DEBUG_INFO,
          ("saopen(%d): dev=0x%x softc=0x%x\n", unit, unit, softc->flags));

      if (cam_periph_acquire(periph) != CAM_REQ_CMP) {
            cam_periph_unlock(periph);
            return (ENXIO);
      }

      if (SA_IS_CTRL(dev)) {
            softc->ctrl_mode = 1;
            cam_periph_unlock(periph);
            return (0);
      }

      if (softc->flags & SA_FLAG_OPEN) {
            error = EBUSY;
      } else if (softc->flags & SA_FLAG_INVALID) {
            error = ENXIO;
      } else {
            /*
             * Preserve whether this is a read_only open.
             */
            softc->open_rdonly = (flags & O_RDWR) == O_RDONLY;

            /*
             * The function samount ensures media is loaded and ready.
             * It also does a device RESERVE if the tape isn't yet mounted.
             *
             * If the mount fails and this was a non-blocking open,
             * make this a 'open_pending_mount' action.
             */
            error = samount(periph, flags, dev);
            if (error && (flags & O_NONBLOCK)) {
                  softc->flags |= SA_FLAG_OPEN;
                  softc->open_pending_mount = 1;
                  cam_periph_unlock(periph);
                  return (0);
            }
      }

      if (error) {
            cam_periph_release(periph);
      } else {
            saprevent(periph, PR_PREVENT);
            softc->flags |= SA_FLAG_OPEN;
      }
      cam_periph_unlock(periph);
      return (error);
}

static int
saclose(struct cdev *dev, int flag, int fmt, struct thread *td)
{
      struct      cam_periph *periph;
      struct      sa_softc *softc;
      int   unit, mode, error, writing, tmp;
      int   closedbits = SA_FLAG_OPEN;

      unit = SAUNIT(dev);
      mode = SAMODE(dev);
      periph = (struct cam_periph *)dev->si_drv1;
      if (periph == NULL)
            return (ENXIO);   

      softc = (struct sa_softc *)periph->softc;

      CAM_DEBUG(periph->path, CAM_DEBUG_TRACE|CAM_DEBUG_INFO,
          ("saclose(%d): dev=0x%x softc=0x%x\n", unit, unit, softc->flags));


      if ((error = cam_periph_lock(periph, PRIBIO)) != 0) {
            return (error);
      }

      softc->open_rdonly = 0; 
      if (SA_IS_CTRL(dev)) {
            softc->ctrl_mode = 0;
            cam_periph_release(periph);
            cam_periph_unlock(periph);
            return (0);
      }

      if (softc->open_pending_mount) {
            softc->flags &= ~SA_FLAG_OPEN;
            softc->open_pending_mount = 0; 
            cam_periph_release(periph);
            cam_periph_unlock(periph);
            return (0);
      }

      /*
       * Were we writing the tape?
       */
      writing = (softc->flags & SA_FLAG_TAPE_WRITTEN) != 0;

      /*
       * See whether or not we need to write filemarks. If this
       * fails, we probably have to assume we've lost tape
       * position.
       */
      error = sacheckeod(periph);
      if (error) {
            xpt_print_path(periph->path);
            printf("failed to write terminating filemark(s)\n");
            softc->flags |= SA_FLAG_TAPE_FROZEN;
      }

      /*
       * Whatever we end up doing, allow users to eject tapes from here on.
       */
      saprevent(periph, PR_ALLOW);

      /*
       * Decide how to end...
       */
      if ((softc->flags & SA_FLAG_TAPE_MOUNTED) == 0) {
            closedbits |= SA_FLAG_TAPE_FROZEN;
      } else switch (mode) {
      case SA_MODE_OFFLINE:
            /*
             * An 'offline' close is an unconditional release of
             * frozen && mount conditions, irrespective of whether
             * these operations succeeded. The reason for this is
             * to allow at least some kind of programmatic way
             * around our state getting all fouled up. If somebody
             * issues an 'offline' command, that will be allowed
             * to clear state.
             */
            (void) sarewind(periph);
            (void) saloadunload(periph, FALSE);
            closedbits |= SA_FLAG_TAPE_MOUNTED|SA_FLAG_TAPE_FROZEN;
            break;
      case SA_MODE_REWIND:
            /*
             * If the rewind fails, return an error- if anyone cares,
             * but not overwriting any previous error.
             *
             * We don't clear the notion of mounted here, but we do
             * clear the notion of frozen if we successfully rewound.
             */
            tmp = sarewind(periph);
            if (tmp) {
                  if (error != 0)
                        error = tmp;
            } else {
                  closedbits |= SA_FLAG_TAPE_FROZEN;
            }
            break;
      case SA_MODE_NOREWIND:
            /*
             * If we're not rewinding/unloading the tape, find out
             * whether we need to back up over one of two filemarks
             * we wrote (if we wrote two filemarks) so that appends
             * from this point on will be sane.
             */
            if (error == 0 && writing && (softc->quirks & SA_QUIRK_2FM)) {
                  tmp = saspace(periph, -1, SS_FILEMARKS);
                  if (tmp) {
                        xpt_print_path(periph->path);
                        printf("unable to backspace over one of double"
                           " filemarks at end of tape\n");
                        xpt_print_path(periph->path);
                        printf("it is possible that this device"
                           " needs a SA_QUIRK_1FM quirk set for it\n");
                        softc->flags |= SA_FLAG_TAPE_FROZEN;
                  }
            }
            break;
      default:
            xpt_print_path(periph->path);
            panic("unknown mode 0x%x in saclose", mode);
            /* NOTREACHED */
            break;
      }

      /*
       * We wish to note here that there are no more filemarks to be written.
       */
      softc->filemarks = 0;
      softc->flags &= ~SA_FLAG_TAPE_WRITTEN;

      /*
       * And we are no longer open for business.
       */
      softc->flags &= ~closedbits;

      /*
       * Inform users if tape state if frozen....
       */
      if (softc->flags & SA_FLAG_TAPE_FROZEN) {
            xpt_print_path(periph->path);
            printf("tape is now frozen- use an OFFLINE, REWIND or MTEOM "
                "command to clear this state.\n");
      }
      
      /* release the device if it is no longer mounted */
      if ((softc->flags & SA_FLAG_TAPE_MOUNTED) == 0)
            sareservereleaseunit(periph, FALSE);

      cam_periph_unlock(periph);
      cam_periph_release(periph);

      return (error);   
}

/*
 * Actually translate the requested transfer into one the physical driver
 * can understand.  The transfer is described by a buf and will include
 * only one physical transfer.
 */
static void
sastrategy(struct bio *bp)
{
      struct cam_periph *periph;
      struct sa_softc *softc;
      int    s;
      
      bp->bio_resid = bp->bio_bcount;
      if (SA_IS_CTRL(bp->bio_dev)) {
            biofinish(bp, NULL, EINVAL);
            return;
      }
      periph = (struct cam_periph *)bp->bio_dev->si_drv1;
      if (periph == NULL) {
            biofinish(bp, NULL, ENXIO);
            return;
      }
      softc = (struct sa_softc *)periph->softc;

      s = splsoftcam();

      if (softc->flags & SA_FLAG_INVALID) {
            splx(s);
            biofinish(bp, NULL, ENXIO);
            return;
      }

      if (softc->flags & SA_FLAG_TAPE_FROZEN) {
            splx(s);
            biofinish(bp, NULL, EPERM);
            return;
      }

      /*
       * This should actually never occur as the write(2)
       * system call traps attempts to write to a read-only
       * file descriptor.
       */
      if (bp->bio_cmd == BIO_WRITE && softc->open_rdonly) {
            splx(s);
            biofinish(bp, NULL, EBADF);
            return;
      }

      splx(s);

      if (softc->open_pending_mount) {
            int error = samount(periph, 0, bp->bio_dev);
            if (error) {
                  biofinish(bp, NULL, ENXIO);
                  return;
            }
            saprevent(periph, PR_PREVENT);
            softc->open_pending_mount = 0;
      }


      /*
       * If it's a null transfer, return immediately
       */
      if (bp->bio_bcount == 0) {
            biodone(bp);
            return;
      }

      /* valid request?  */
      if (softc->flags & SA_FLAG_FIXED) {
            /*
             * Fixed block device.  The byte count must
             * be a multiple of our block size.
             */
            if (((softc->blk_mask != ~0) &&
                ((bp->bio_bcount & softc->blk_mask) != 0)) ||
                ((softc->blk_mask == ~0) &&
                ((bp->bio_bcount % softc->min_blk) != 0))) {
                  xpt_print_path(periph->path);
                  printf("Invalid request.  Fixed block device "
                         "requests must be a multiple "
                         "of %d bytes\n", softc->min_blk);
                  biofinish(bp, NULL, EINVAL);
                  return;
            }
      } else if ((bp->bio_bcount > softc->max_blk) ||
               (bp->bio_bcount < softc->min_blk) ||
               (bp->bio_bcount & softc->blk_mask) != 0) {

            xpt_print_path(periph->path);
            printf("Invalid request.  Variable block device "
                "requests must be ");
            if (softc->blk_mask != 0) {
                  printf("a multiple of %d ", (0x1 << softc->blk_gran));
            }
            printf("between %d and %d bytes\n", softc->min_blk,
                softc->max_blk);
            biofinish(bp, NULL, EINVAL);
            return;
        }
      
      /*
       * Mask interrupts so that the device cannot be invalidated until
       * after we are in the queue.  Otherwise, we might not properly
       * clean up one of the buffers.
       */
      s = splbio();
      
      /*
       * Place it at the end of the queue.
       */
      bioq_insert_tail(&softc->bio_queue, bp);
      softc->queue_count++;
#if   0
      CAM_DEBUG(periph->path, CAM_DEBUG_INFO,
          ("sastrategy: queuing a %ld %s byte %s\n", bp->bio_bcount,
          (softc->flags & SA_FLAG_FIXED)?  "fixed" : "variable",
          (bp->bio_cmd == BIO_READ)? "read" : "write"));
#endif
      if (softc->queue_count > 1) {
            CAM_DEBUG(periph->path, CAM_DEBUG_INFO,
                ("sastrategy: queue count now %d\n", softc->queue_count));
      }
      splx(s);
      
      /*
       * Schedule ourselves for performing the work.
       */
      xpt_schedule(periph, 1);

      return;
}


#define     PENDING_MOUNT_CHECK(softc, periph, dev)         \
      if (softc->open_pending_mount) {          \
            error = samount(periph, 0, dev);    \
            if (error) {                        \
                  break;                        \
            }                             \
            saprevent(periph, PR_PREVENT);            \
            softc->open_pending_mount = 0;            \
      }

static int
saioctl(struct cdev *dev, u_long cmd, caddr_t arg, int flag, struct thread *td)
{
      struct cam_periph *periph;
      struct sa_softc *softc;
      scsi_space_code spaceop;
      int didlockperiph = 0;
      int s;
      int mode;
      int error = 0;

      mode = SAMODE(dev);
      error = 0;        /* shut up gcc */
      spaceop = 0;            /* shut up gcc */

      periph = (struct cam_periph *)dev->si_drv1;
      if (periph == NULL)
            return (ENXIO);   

      softc = (struct sa_softc *)periph->softc;

      /*
       * Check for control mode accesses. We allow MTIOCGET and
       * MTIOCERRSTAT (but need to be the only one open in order
       * to clear latched status), and MTSETBSIZE, MTSETDNSTY
       * and MTCOMP (but need to be the only one accessing this
       * device to run those).
       */

      if (SA_IS_CTRL(dev)) {
            switch (cmd) {
            case MTIOCGETEOTMODEL:
            case MTIOCGET:
                  break;
            case MTIOCERRSTAT:
                  /*
                   * If the periph isn't already locked, lock it
                   * so our MTIOCERRSTAT can reset latched error stats.
                   *
                   * If the periph is already locked, skip it because
                   * we're just getting status and it'll be up to the
                   * other thread that has this device open to do
                   * an MTIOCERRSTAT that would clear latched status.
                   */
                  s = splsoftcam();
                  if ((periph->flags & CAM_PERIPH_LOCKED) == 0) {
                        error = cam_periph_lock(periph, PRIBIO|PCATCH);
                        if (error != 0) {
                              splx(s);
                              return (error);
                        }
                        didlockperiph = 1;
                  }
                  break;

            case MTIOCTOP:
            {
                  struct mtop *mt = (struct mtop *) arg;

                  /*
                   * Check to make sure it's an OP we can perform
                   * with no media inserted.
                   */
                  switch (mt->mt_op) {
                  case MTSETBSIZ:
                  case MTSETDNSTY:
                  case MTCOMP:
                        mt = NULL;
                        /* FALLTHROUGH */
                  default:
                        break;
                  }
                  if (mt != NULL) {
                        break;
                  }
                  /* FALLTHROUGH */
            }
            case MTIOCSETEOTMODEL:
                  /*
                   * We need to acquire the peripheral here rather
                   * than at open time because we are sharing writable
                   * access to data structures.
                   */
                  s = splsoftcam();
                  error = cam_periph_lock(periph, PRIBIO|PCATCH);
                  if (error != 0) {
                        splx(s);
                        return (error);
                  }
                  didlockperiph = 1;
                  break;

            default:
                  return (EINVAL);
            }
      }

      /*
       * Find the device that the user is talking about
       */
      switch (cmd) {
      case MTIOCGET:
      {
            struct mtget *g = (struct mtget *)arg;

            /*
             * If this isn't the control mode device, actually go out
             * and ask the drive again what it's set to.
             */
            if (!SA_IS_CTRL(dev) && !softc->open_pending_mount) {
                  u_int8_t write_protect;
                  int comp_enabled, comp_supported;
                  error = sagetparams(periph, SA_PARAM_ALL,
                      &softc->media_blksize, &softc->media_density,
                      &softc->media_numblks, &softc->buffer_mode,
                      &write_protect, &softc->speed, &comp_supported,
                      &comp_enabled, &softc->comp_algorithm, NULL);
                  if (error)
                        break;
                  if (write_protect)
                        softc->flags |= SA_FLAG_TAPE_WP;
                  else
                        softc->flags &= ~SA_FLAG_TAPE_WP;
                  softc->flags &= ~(SA_FLAG_COMP_SUPP|
                      SA_FLAG_COMP_ENABLED|SA_FLAG_COMP_UNSUPP);
                  if (comp_supported) {
                        if (softc->saved_comp_algorithm == 0)
                              softc->saved_comp_algorithm =
                                  softc->comp_algorithm;
                        softc->flags |= SA_FLAG_COMP_SUPP;
                        if (comp_enabled)
                              softc->flags |= SA_FLAG_COMP_ENABLED;
                  } else  
                        softc->flags |= SA_FLAG_COMP_UNSUPP;
            }
            bzero(g, sizeof(struct mtget));
            g->mt_type = MT_ISAR;
            if (softc->flags & SA_FLAG_COMP_UNSUPP) {
                  g->mt_comp = MT_COMP_UNSUPP;
                  g->mt_comp0 = MT_COMP_UNSUPP;
                  g->mt_comp1 = MT_COMP_UNSUPP;
                  g->mt_comp2 = MT_COMP_UNSUPP;
                  g->mt_comp3 = MT_COMP_UNSUPP;
            } else {
                  if ((softc->flags & SA_FLAG_COMP_ENABLED) == 0) {
                        g->mt_comp = MT_COMP_DISABLED;
                  } else {
                        g->mt_comp = softc->comp_algorithm;
                  }
                  g->mt_comp0 = softc->comp_algorithm;
                  g->mt_comp1 = softc->comp_algorithm;
                  g->mt_comp2 = softc->comp_algorithm;
                  g->mt_comp3 = softc->comp_algorithm;
            }
            g->mt_density = softc->media_density;
            g->mt_density0 = softc->media_density;
            g->mt_density1 = softc->media_density;
            g->mt_density2 = softc->media_density;
            g->mt_density3 = softc->media_density;
            g->mt_blksiz = softc->media_blksize;
            g->mt_blksiz0 = softc->media_blksize;
            g->mt_blksiz1 = softc->media_blksize;
            g->mt_blksiz2 = softc->media_blksize;
            g->mt_blksiz3 = softc->media_blksize;
            g->mt_fileno = softc->fileno;
            g->mt_blkno = softc->blkno;
            g->mt_dsreg = (short) softc->dsreg;
            /*
             * Yes, we know that this is likely to overflow
             */
            if (softc->last_resid_was_io) {
                  if ((g->mt_resid = (short) softc->last_io_resid) != 0) {
                        if (SA_IS_CTRL(dev) == 0 || didlockperiph) {
                              softc->last_io_resid = 0;
                        }
                  }
            } else {
                  if ((g->mt_resid = (short)softc->last_ctl_resid) != 0) {
                        if (SA_IS_CTRL(dev) == 0 || didlockperiph) {
                              softc->last_ctl_resid = 0;
                        }
                  }
            }
            error = 0;
            break;
      }
      case MTIOCERRSTAT:
      {
            struct scsi_tape_errors *sep =
                &((union mterrstat *)arg)->scsi_errstat;

            CAM_DEBUG(periph->path, CAM_DEBUG_TRACE,
                ("saioctl: MTIOCERRSTAT\n"));

            bzero(sep, sizeof(*sep));
            sep->io_resid = softc->last_io_resid;
            bcopy((caddr_t) &softc->last_io_sense, sep->io_sense,
                sizeof (sep->io_sense));
            bcopy((caddr_t) &softc->last_io_cdb, sep->io_cdb,
                sizeof (sep->io_cdb));
            sep->ctl_resid = softc->last_ctl_resid;
            bcopy((caddr_t) &softc->last_ctl_sense, sep->ctl_sense,
                sizeof (sep->ctl_sense));
            bcopy((caddr_t) &softc->last_ctl_cdb, sep->ctl_cdb,
                sizeof (sep->ctl_cdb));

            if ((SA_IS_CTRL(dev) == 0 && softc->open_pending_mount) ||
                didlockperiph)
                  bzero((caddr_t) &softc->errinfo,
                      sizeof (softc->errinfo));
            error = 0;
            break;
      }
      case MTIOCTOP:
      {
            struct mtop *mt;
            int    count;

            PENDING_MOUNT_CHECK(softc, periph, dev);

            mt = (struct mtop *)arg;


            CAM_DEBUG(periph->path, CAM_DEBUG_TRACE,
                   ("saioctl: op=0x%x count=0x%x\n",
                    mt->mt_op, mt->mt_count));

            count = mt->mt_count;
            switch (mt->mt_op) {
            case MTWEOF:      /* write an end-of-file marker */
                  /*
                   * We don't need to clear the SA_FLAG_TAPE_WRITTEN
                   * flag because by keeping track of filemarks
                   * we have last written we know ehether or not
                   * we need to write more when we close the device.
                   */
                  error = sawritefilemarks(periph, count, FALSE);
                  break;
            case MTWSS: /* write a setmark */
                  error = sawritefilemarks(periph, count, TRUE);
                  break;
            case MTBSR: /* backward space record */
            case MTFSR: /* forward space record */
            case MTBSF: /* backward space file */
            case MTFSF: /* forward space file */
            case MTBSS: /* backward space setmark */
            case MTFSS: /* forward space setmark */
            case MTEOD: /* space to end of recorded medium */
            {
                  int nmarks;

                  spaceop = SS_FILEMARKS;
                  nmarks = softc->filemarks;
                  error = sacheckeod(periph);
                  if (error) {
                        xpt_print_path(periph->path);
                        printf("EOD check prior to spacing failed\n");
                        softc->flags |= SA_FLAG_EIO_PENDING;
                        break;
                  }
                  nmarks -= softc->filemarks;
                  switch(mt->mt_op) {
                  case MTBSR:
                        count = -count;
                        /* FALLTHROUGH */
                  case MTFSR:
                        spaceop = SS_BLOCKS;
                        break;
                  case MTBSF:
                        count = -count;
                        /* FALLTHROUGH */
                  case MTFSF:
                        break;
                  case MTBSS:
                        count = -count;
                        /* FALLTHROUGH */
                  case MTFSS:
                        spaceop = SS_SETMARKS;
                        break;
                  case MTEOD:
                        spaceop = SS_EOD;
                        count = 0;
                        nmarks = 0;
                        break;
                  default:
                        error = EINVAL;
                        break;
                  }
                  if (error)
                        break;

                  nmarks = softc->filemarks;
                  /*
                   * XXX: Why are we checking again?
                   */
                  error = sacheckeod(periph);
                  if (error)
                        break;
                  nmarks -= softc->filemarks;
                  error = saspace(periph, count - nmarks, spaceop);
                  /*
                   * At this point, clear that we've written the tape
                   * and that we've written any filemarks. We really
                   * don't know what the applications wishes to do next-
                   * the sacheckeod's will make sure we terminated the
                   * tape correctly if we'd been writing, but the next
                   * action the user application takes will set again
                   * whether we need to write filemarks.
                   */
                  softc->flags &=
                      ~(SA_FLAG_TAPE_WRITTEN|SA_FLAG_TAPE_FROZEN);
                  softc->filemarks = 0;
                  break;
            }
            case MTREW: /* rewind */
                  PENDING_MOUNT_CHECK(softc, periph, dev);
                  (void) sacheckeod(periph);
                  error = sarewind(periph);
                  /* see above */
                  softc->flags &=
                      ~(SA_FLAG_TAPE_WRITTEN|SA_FLAG_TAPE_FROZEN);
                  softc->flags &= ~SA_FLAG_ERR_PENDING;
                  softc->filemarks = 0;
                  break;
            case MTERASE:     /* erase */
                  PENDING_MOUNT_CHECK(softc, periph, dev);
                  error = saerase(periph, count);
                  softc->flags &=
                      ~(SA_FLAG_TAPE_WRITTEN|SA_FLAG_TAPE_FROZEN);
                  softc->flags &= ~SA_FLAG_ERR_PENDING;
                  break;
            case MTRETENS:    /* re-tension tape */
                  PENDING_MOUNT_CHECK(softc, periph, dev);
                  error = saretension(periph);        
                  softc->flags &=
                      ~(SA_FLAG_TAPE_WRITTEN|SA_FLAG_TAPE_FROZEN);
                  softc->flags &= ~SA_FLAG_ERR_PENDING;
                  break;
            case MTOFFL:      /* rewind and put the drive offline */

                  PENDING_MOUNT_CHECK(softc, periph, dev);

                  (void) sacheckeod(periph);
                  /* see above */
                  softc->flags &= ~SA_FLAG_TAPE_WRITTEN;
                  softc->filemarks = 0;

                  error = sarewind(periph);
                  /* clear the frozen flag anyway */
                  softc->flags &= ~SA_FLAG_TAPE_FROZEN;

                  /*
                   * Be sure to allow media removal before ejecting.
                   */

                  saprevent(periph, PR_ALLOW);
                  if (error == 0) {
                        error = saloadunload(periph, FALSE);
                        if (error == 0) {
                              softc->flags &= ~SA_FLAG_TAPE_MOUNTED;
                        }
                  }
                  break;

            case MTNOP: /* no operation, sets status only */
            case MTCACHE:     /* enable controller cache */
            case MTNOCACHE:   /* disable controller cache */
                  error = 0;
                  break;

            case MTSETBSIZ:   /* Set block size for device */

                  PENDING_MOUNT_CHECK(softc, periph, dev);

                  error = sasetparams(periph, SA_PARAM_BLOCKSIZE, count,
                                  0, 0, 0);
                  if (error == 0) {
                        softc->last_media_blksize =
                            softc->media_blksize;
                        softc->media_blksize = count;
                        if (count) {
                              softc->flags |= SA_FLAG_FIXED;
                              if (powerof2(count)) {
                                    softc->blk_shift =
                                        ffs(count) - 1;
                                    softc->blk_mask = count - 1;
                              } else {
                                    softc->blk_mask = ~0;
                                    softc->blk_shift = 0;
                              }
                              /*
                               * Make the user's desire 'persistent'.
                               */
                              softc->quirks &= ~SA_QUIRK_VARIABLE;
                              softc->quirks |= SA_QUIRK_FIXED;
                        } else {
                              softc->flags &= ~SA_FLAG_FIXED;
                              if (softc->max_blk == 0) {
                                    softc->max_blk = ~0;
                              }
                              softc->blk_shift = 0;
                              if (softc->blk_gran != 0) {
                                    softc->blk_mask =
                                        softc->blk_gran - 1;
                              } else {
                                    softc->blk_mask = 0;
                              }
                              /*
                               * Make the user's desire 'persistent'.
                               */
                              softc->quirks |= SA_QUIRK_VARIABLE;
                              softc->quirks &= ~SA_QUIRK_FIXED;
                        }
                  }
                  break;
            case MTSETDNSTY:  /* Set density for device and mode */
                  PENDING_MOUNT_CHECK(softc, periph, dev);

                  if (count > UCHAR_MAX) {
                        error = EINVAL;   
                        break;
                  } else {
                        error = sasetparams(periph, SA_PARAM_DENSITY,
                                        0, count, 0, 0);
                  }
                  break;
            case MTCOMP:      /* enable compression */
                  PENDING_MOUNT_CHECK(softc, periph, dev);
                  /*
                   * Some devices don't support compression, and
                   * don't like it if you ask them for the
                   * compression page.
                   */
                  if ((softc->quirks & SA_QUIRK_NOCOMP) ||
                      (softc->flags & SA_FLAG_COMP_UNSUPP)) {
                        error = ENODEV;
                        break;
                  }
                  error = sasetparams(periph, SA_PARAM_COMPRESSION,
                      0, 0, count, SF_NO_PRINT);
                  break;
            default:
                  error = EINVAL;
            }
            break;
      }
      case MTIOCIEOT:
      case MTIOCEEOT:
            error = 0;
            break;
      case MTIOCRDSPOS:
            PENDING_MOUNT_CHECK(softc, periph, dev);
            error = sardpos(periph, 0, (u_int32_t *) arg);
            break;
      case MTIOCRDHPOS:
            PENDING_MOUNT_CHECK(softc, periph, dev);
            error = sardpos(periph, 1, (u_int32_t *) arg);
            break;
      case MTIOCSLOCATE:
            PENDING_MOUNT_CHECK(softc, periph, dev);
            error = sasetpos(periph, 0, (u_int32_t *) arg);
            break;
      case MTIOCHLOCATE:
            PENDING_MOUNT_CHECK(softc, periph, dev);
            error = sasetpos(periph, 1, (u_int32_t *) arg);
            break;
      case MTIOCGETEOTMODEL:
            error = 0;
            if (softc->quirks & SA_QUIRK_1FM)
                  mode = 1;
            else
                  mode = 2;
            *((u_int32_t *) arg) = mode;
            break;
      case MTIOCSETEOTMODEL:
            error = 0;
            switch (*((u_int32_t *) arg)) {
            case 1:
                  softc->quirks &= ~SA_QUIRK_2FM;
                  softc->quirks |= SA_QUIRK_1FM;
                  break;
            case 2:
                  softc->quirks &= ~SA_QUIRK_1FM;
                  softc->quirks |= SA_QUIRK_2FM;
                  break;
            default:
                  error = EINVAL;
                  break;
            }
            break;
      default:
            error = cam_periph_ioctl(periph, cmd, arg, saerror);
            break;
      }

      /*
       * Check to see if we cleared a frozen state
       */
      if (error == 0 && (softc->flags & SA_FLAG_TAPE_FROZEN)) {
            switch(cmd) {
            case MTIOCRDSPOS:
            case MTIOCRDHPOS:
            case MTIOCSLOCATE:
            case MTIOCHLOCATE:
                  softc->fileno = (daddr_t) -1;
                  softc->blkno = (daddr_t) -1;
                  softc->flags &= ~SA_FLAG_TAPE_FROZEN;
                  xpt_print_path(periph->path);
                  printf("tape state now unfrozen.\n");
                  break;
            default:
                  break;
            }
      }
      if (didlockperiph) {
            cam_periph_unlock(periph);
      }
      return (error);
}

static void
sainit(void)
{
      cam_status status;
      struct cam_path *path;

      /*
       * Install a global async callback.
       */
      status = xpt_create_path(&path, NULL, CAM_XPT_PATH_ID,
                         CAM_TARGET_WILDCARD, CAM_LUN_WILDCARD);

      if (status == CAM_REQ_CMP) {
            /* Register the async callbacks of interrest */
            struct ccb_setasync csa; /*
                                * This is an immediate CCB,
                                * so using the stack is OK
                                */
            xpt_setup_ccb(&csa.ccb_h, path, 5);
            csa.ccb_h.func_code = XPT_SASYNC_CB;
            csa.event_enable = AC_FOUND_DEVICE;
            csa.callback = saasync;
            csa.callback_arg = NULL;
            xpt_action((union ccb *)&csa);
            status = csa.ccb_h.status;
            xpt_free_path(path);
      }

      if (status != CAM_REQ_CMP) {
            printf("sa: Failed to attach master async callback "
                   "due to status 0x%x!\n", status);
      }
}

static void
saoninvalidate(struct cam_periph *periph)
{
      struct sa_softc *softc;
      struct ccb_setasync csa;
      int s;

      softc = (struct sa_softc *)periph->softc;

      /*
       * De-register any async callbacks.
       */
      xpt_setup_ccb(&csa.ccb_h, periph->path,
                  /* priority */ 5);
      csa.ccb_h.func_code = XPT_SASYNC_CB;
      csa.event_enable = 0;
      csa.callback = saasync;
      csa.callback_arg = periph;
      xpt_action((union ccb *)&csa);

      softc->flags |= SA_FLAG_INVALID;

      /*
       * Although the oninvalidate() routines are always called at
       * splsoftcam, we need to be at splbio() here to keep the buffer
       * queue from being modified while we traverse it.
       */
      s = splbio();

      /*
       * Return all queued I/O with ENXIO.
       * XXX Handle any transactions queued to the card
       *     with XPT_ABORT_CCB.
       */
      bioq_flush(&softc->bio_queue, NULL, ENXIO);
      softc->queue_count = 0;
      splx(s);

      xpt_print_path(periph->path);
      printf("lost device\n");

}

static void
sacleanup(struct cam_periph *periph)
{
      struct sa_softc *softc;
      int i;

      softc = (struct sa_softc *)periph->softc;

      devstat_remove_entry(softc->device_stats);

      destroy_dev(softc->devs.ctl_dev);

      for (i = 0; i < SA_NUM_MODES; i++) {
            destroy_dev(softc->devs.mode_devs[i].r_dev);
            destroy_dev(softc->devs.mode_devs[i].nr_dev);
            destroy_dev(softc->devs.mode_devs[i].er_dev);
      }

      xpt_print_path(periph->path);
      printf("removing device entry\n");
      free(softc, M_SCSISA);
}

static void
saasync(void *callback_arg, u_int32_t code,
      struct cam_path *path, void *arg)
{
      struct cam_periph *periph;

      periph = (struct cam_periph *)callback_arg;
      switch (code) {
      case AC_FOUND_DEVICE:
      {
            struct ccb_getdev *cgd;
            cam_status status;

            cgd = (struct ccb_getdev *)arg;
            if (cgd == NULL)
                  break;

            if (SID_TYPE(&cgd->inq_data) != T_SEQUENTIAL)
                  break;

            /*
             * Allocate a peripheral instance for
             * this device and start the probe
             * process.
             */
            status = cam_periph_alloc(saregister, saoninvalidate,
                                sacleanup, sastart,
                                "sa", CAM_PERIPH_BIO, cgd->ccb_h.path,
                                saasync, AC_FOUND_DEVICE, cgd);

            if (status != CAM_REQ_CMP
             && status != CAM_REQ_INPROG)
                  printf("saasync: Unable to probe new device "
                        "due to status 0x%x\n", status);
            break;
      }
      default:
            cam_periph_async(periph, code, path, arg);
            break;
      }
}

static cam_status
saregister(struct cam_periph *periph, void *arg)
{
      struct sa_softc *softc;
      struct ccb_setasync csa;
      struct ccb_getdev *cgd;
      caddr_t match;
      int i;
      
      cgd = (struct ccb_getdev *)arg;
      if (periph == NULL) {
            printf("saregister: periph was NULL!!\n");
            return (CAM_REQ_CMP_ERR);
      }

      if (cgd == NULL) {
            printf("saregister: no getdev CCB, can't register device\n");
            return (CAM_REQ_CMP_ERR);
      }

      softc = (struct sa_softc *)
          malloc(sizeof (*softc), M_SCSISA, M_NOWAIT | M_ZERO);
      if (softc == NULL) {
            printf("saregister: Unable to probe new device. "
                   "Unable to allocate softc\n");                       
            return (CAM_REQ_CMP_ERR);
      }
      softc->scsi_rev = SID_ANSI_REV(&cgd->inq_data);
      softc->state = SA_STATE_NORMAL;
      softc->fileno = (daddr_t) -1;
      softc->blkno = (daddr_t) -1;

      bioq_init(&softc->bio_queue);
      periph->softc = softc;

      /*
       * See if this device has any quirks.
       */
      match = cam_quirkmatch((caddr_t)&cgd->inq_data,
                         (caddr_t)sa_quirk_table,
                         sizeof(sa_quirk_table)/sizeof(*sa_quirk_table),
                         sizeof(*sa_quirk_table), scsi_inquiry_match);

      if (match != NULL) {
            softc->quirks = ((struct sa_quirk_entry *)match)->quirks;
            softc->last_media_blksize =
                ((struct sa_quirk_entry *)match)->prefblk;
#ifdef      CAMDEBUG
            xpt_print_path(periph->path);
            printf("found quirk entry %d\n", (int)
                (((struct sa_quirk_entry *) match) - sa_quirk_table));
#endif
      } else
            softc->quirks = SA_QUIRK_NONE;

      /*
       * The SA driver supports a blocksize, but we don't know the
       * blocksize until we media is inserted.  So, set a flag to
       * indicate that the blocksize is unavailable right now.
       */
      softc->device_stats = devstat_new_entry("sa", periph->unit_number, 0,
          DEVSTAT_BS_UNAVAILABLE, SID_TYPE(&cgd->inq_data) |
          DEVSTAT_TYPE_IF_SCSI, DEVSTAT_PRIORITY_TAPE);

      softc->devs.ctl_dev = make_dev(&sa_cdevsw, SAMINOR(SA_CTLDEV,
          periph->unit_number, 0, SA_ATYPE_R), UID_ROOT, GID_OPERATOR,
          0660, "%s%d.ctl", periph->periph_name, periph->unit_number);
      softc->devs.ctl_dev->si_drv1 = periph;

      for (i = 0; i < SA_NUM_MODES; i++) {

            softc->devs.mode_devs[i].r_dev = make_dev(&sa_cdevsw,
                SAMINOR(SA_NOT_CTLDEV, periph->unit_number, i, SA_ATYPE_R),
                UID_ROOT, GID_OPERATOR, 0660, "%s%d.%d",
                periph->periph_name, periph->unit_number, i);
            softc->devs.mode_devs[i].r_dev->si_drv1 = periph;

            softc->devs.mode_devs[i].nr_dev = make_dev(&sa_cdevsw,
                SAMINOR(SA_NOT_CTLDEV, periph->unit_number, i, SA_ATYPE_NR),
                UID_ROOT, GID_OPERATOR, 0660, "n%s%d.%d",
                periph->periph_name, periph->unit_number, i);
            softc->devs.mode_devs[i].nr_dev->si_drv1 = periph;

            softc->devs.mode_devs[i].er_dev = make_dev(&sa_cdevsw,
                SAMINOR(SA_NOT_CTLDEV, periph->unit_number, i, SA_ATYPE_ER),
                UID_ROOT, GID_OPERATOR, 0660, "e%s%d.%d",
                periph->periph_name, periph->unit_number, i);
            softc->devs.mode_devs[i].er_dev->si_drv1 = periph;

            /*
             * Make the (well known) aliases for the first mode.
             */
            if (i == 0) {
                  struct cdev *alias;

                  alias = make_dev_alias(softc->devs.mode_devs[i].r_dev,
                     "%s%d", periph->periph_name, periph->unit_number);
                  alias->si_drv1 = periph;
                  alias = make_dev_alias(softc->devs.mode_devs[i].nr_dev,
                      "n%s%d", periph->periph_name, periph->unit_number);
                  alias->si_drv1 = periph;
                  alias = make_dev_alias(softc->devs.mode_devs[i].er_dev,
                      "e%s%d", periph->periph_name, periph->unit_number);
                  alias->si_drv1 = periph;
            }
      }

      /*
       * Add an async callback so that we get
       * notified if this device goes away.
       */
      xpt_setup_ccb(&csa.ccb_h, periph->path, /* priority */ 5);
      csa.ccb_h.func_code = XPT_SASYNC_CB;
      csa.event_enable = AC_LOST_DEVICE;
      csa.callback = saasync;
      csa.callback_arg = periph;
      xpt_action((union ccb *)&csa);

      xpt_announce_periph(periph, NULL);

      return (CAM_REQ_CMP);
}

static void
sastart(struct cam_periph *periph, union ccb *start_ccb)
{
      struct sa_softc *softc;

      softc = (struct sa_softc *)periph->softc;

      CAM_DEBUG(periph->path, CAM_DEBUG_TRACE, ("sastart\n"));

      
      switch (softc->state) {
      case SA_STATE_NORMAL:
      {
            /* Pull a buffer from the queue and get going on it */            
            struct bio *bp;
            int s;

            /*
             * See if there is a buf with work for us to do..
             */
            s = splbio();
            bp = bioq_first(&softc->bio_queue);
            if (periph->immediate_priority <= periph->pinfo.priority) {
                  CAM_DEBUG_PRINT(CAM_DEBUG_SUBTRACE,
                              ("queuing for immediate ccb\n"));
                  Set_CCB_Type(start_ccb, SA_CCB_WAITING);
                  SLIST_INSERT_HEAD(&periph->ccb_list, &start_ccb->ccb_h,
                                periph_links.sle);
                  periph->immediate_priority = CAM_PRIORITY_NONE;
                  splx(s);
                  wakeup(&periph->ccb_list);
            } else if (bp == NULL) {
                  splx(s);
                  xpt_release_ccb(start_ccb);
            } else if ((softc->flags & SA_FLAG_ERR_PENDING) != 0) {
                  struct bio *done_bp;
again:
                  softc->queue_count--;
                  bioq_remove(&softc->bio_queue, bp);
                  bp->bio_resid = bp->bio_bcount;
                  done_bp = bp;
                  if ((softc->flags & SA_FLAG_EOM_PENDING) != 0) {
                        /*
                         * We now just clear errors in this case
                         * and let the residual be the notifier.
                         */
                        bp->bio_error = 0;
                  } else if ((softc->flags & SA_FLAG_EOF_PENDING) != 0) {
                        /*
                         * This can only happen if we're reading
                         * in fixed length mode. In this case,
                         * we dump the rest of the list the
                         * same way.
                         */
                        bp->bio_error = 0;
                        if (bioq_first(&softc->bio_queue) != NULL) {
                              biodone(done_bp);
                              goto again;
                        }
                  } else if ((softc->flags & SA_FLAG_EIO_PENDING) != 0) {
                        bp->bio_error = EIO;
                        bp->bio_flags |= BIO_ERROR;
                  }
                  bp = bioq_first(&softc->bio_queue);
                  /*
                   * Only if we have no other buffers queued up
                   * do we clear the pending error flag.
                   */
                  if (bp == NULL)
                        softc->flags &= ~SA_FLAG_ERR_PENDING;
                  CAM_DEBUG(periph->path, CAM_DEBUG_INFO,
                      ("sastart- ERR_PENDING now 0x%x, bp is %sNULL, "
                      "%d more buffers queued up\n",
                      (softc->flags & SA_FLAG_ERR_PENDING),
                      (bp != NULL)? "not " : " ", softc->queue_count));
                  splx(s);
                  xpt_release_ccb(start_ccb);
                  biodone(done_bp);
            } else {
                  u_int32_t length;

                  bioq_remove(&softc->bio_queue, bp);
                  softc->queue_count--;

                  if ((softc->flags & SA_FLAG_FIXED) != 0) {
                        if (softc->blk_shift != 0) {
                              length =
                                  bp->bio_bcount >> softc->blk_shift;
                        } else if (softc->media_blksize != 0) {
                              length = bp->bio_bcount /
                                  softc->media_blksize;
                        } else {
                              bp->bio_error = EIO;
                              xpt_print_path(periph->path);
                              printf("zero blocksize for "
                                  "FIXED length writes?\n");
                              splx(s);
                              biodone(bp);
                              break;
                        }
#if   0
                        CAM_DEBUG(start_ccb->ccb_h.path, CAM_DEBUG_INFO,
                            ("issuing a %d fixed record %s\n",
                            length,  (bp->bio_cmd == BIO_READ)? "read" :
                            "write"));
#endif
                  } else {
                        length = bp->bio_bcount;
#if   0
                        CAM_DEBUG(start_ccb->ccb_h.path, CAM_DEBUG_INFO,
                            ("issuing a %d variable byte %s\n",
                            length,  (bp->bio_cmd == BIO_READ)? "read" :
                            "write"));
#endif
                  }
                  devstat_start_transaction_bio(softc->device_stats, bp);
                  /*
                   * Some people have theorized that we should
                   * suppress illegal length indication if we are
                   * running in variable block mode so that we don't
                   * have to request sense every time our requested
                   * block size is larger than the written block.
                   * The residual information from the ccb allows
                   * us to identify this situation anyway.  The only
                   * problem with this is that we will not get
                   * information about blocks that are larger than
                   * our read buffer unless we set the block size
                   * in the mode page to something other than 0.
                   *
                   * I believe that this is a non-issue. If user apps
                   * don't adjust their read size to match our record
                   * size, that's just life. Anyway, the typical usage
                   * would be to issue, e.g., 64KB reads and occasionally
                   * have to do deal with 512 byte or 1KB intermediate
                   * records.
                   */
                  softc->dsreg = (bp->bio_cmd == BIO_READ)?
                      MTIO_DSREG_RD : MTIO_DSREG_WR;
                  scsi_sa_read_write(&start_ccb->csio, 0, sadone,
                      MSG_SIMPLE_Q_TAG, (bp->bio_cmd == BIO_READ),
                      FALSE, (softc->flags & SA_FLAG_FIXED) != 0,
                      length, bp->bio_data, bp->bio_bcount, SSD_FULL_SIZE,
                      IO_TIMEOUT);
                  start_ccb->ccb_h.ccb_pflags &= ~SA_POSITION_UPDATED;
                  Set_CCB_Type(start_ccb, SA_CCB_BUFFER_IO);
                  start_ccb->ccb_h.ccb_bp = bp;
                  bp = bioq_first(&softc->bio_queue);
                  splx(s);
                  xpt_action(start_ccb);
            }
            
            if (bp != NULL) {
                  /* Have more work to do, so ensure we stay scheduled */
                  xpt_schedule(periph, 1);
            }
            break;
      }
      case SA_STATE_ABNORMAL:
      default:
            panic("state 0x%x in sastart", softc->state);
            break;
      }
}


static void
sadone(struct cam_periph *periph, union ccb *done_ccb)
{
      struct sa_softc *softc;
      struct ccb_scsiio *csio;

      softc = (struct sa_softc *)periph->softc;
      csio = &done_ccb->csio;
      switch (CCB_Type(csio)) {
      case SA_CCB_BUFFER_IO:
      {
            struct bio *bp;
            int error;

            softc->dsreg = MTIO_DSREG_REST;
            bp = (struct bio *)done_ccb->ccb_h.ccb_bp;
            error = 0;
            if ((done_ccb->ccb_h.status & CAM_STATUS_MASK) != CAM_REQ_CMP) {
                  if ((error = saerror(done_ccb, 0, 0)) == ERESTART) {
                        /*
                         * A retry was scheduled, so just return.
                         */
                        return;
                  }
            }

            if (error == EIO) {
                  int s;                  

                  /*
                   * Catastrophic error. Mark the tape as frozen
                   * (we no longer know tape position).
                   *
                   * Return all queued I/O with EIO, and unfreeze
                   * our queue so that future transactions that
                   * attempt to fix this problem can get to the
                   * device.
                   *
                   */

                  s = splbio();
                  softc->flags |= SA_FLAG_TAPE_FROZEN;
                  bioq_flush(&softc->bio_queue, NULL, EIO);
                  splx(s);
            }
            if (error != 0) {
                  bp->bio_resid = bp->bio_bcount;
                  bp->bio_error = error;
                  bp->bio_flags |= BIO_ERROR;
                  /*
                   * In the error case, position is updated in saerror.
                   */
            } else {
                  bp->bio_resid = csio->resid;
                  bp->bio_error = 0;
                  if (csio->resid != 0) {
                        bp->bio_flags |= BIO_ERROR;
                  }
                  if (bp->bio_cmd == BIO_WRITE) {
                        softc->flags |= SA_FLAG_TAPE_WRITTEN;
                        softc->filemarks = 0;
                  }
                  if (!(csio->ccb_h.ccb_pflags & SA_POSITION_UPDATED) &&
                      (softc->blkno != (daddr_t) -1)) {
                        if ((softc->flags & SA_FLAG_FIXED) != 0) {
                              u_int32_t l;
                              if (softc->blk_shift != 0) {
                                    l = bp->bio_bcount >>
                                          softc->blk_shift;
                              } else {
                                    l = bp->bio_bcount /
                                          softc->media_blksize;
                              }
                              softc->blkno += (daddr_t) l;
                        } else {
                              softc->blkno++;
                        }
                  }
            }
            /*
             * If we had an error (immediate or pending),
             * release the device queue now.
             */
            if (error || (softc->flags & SA_FLAG_ERR_PENDING))
                  cam_release_devq(done_ccb->ccb_h.path, 0, 0, 0, 0);
#ifdef      CAMDEBUG
            if (error || bp->bio_resid) {
                  CAM_DEBUG(periph->path, CAM_DEBUG_INFO,
                          ("error %d resid %ld count %ld\n", error,
                          bp->bio_resid, bp->bio_bcount));
            }
#endif
            biofinish(bp, softc->device_stats, 0);
            break;
      }
      case SA_CCB_WAITING:
      {
            /* Caller will release the CCB */
            wakeup(&done_ccb->ccb_h.cbfcnp);
            return;
      }
      }
      xpt_release_ccb(done_ccb);
}

/*
 * Mount the tape (make sure it's ready for I/O).
 */
static int
samount(struct cam_periph *periph, int oflags, struct cdev *dev)
{
      struct      sa_softc *softc;
      union ccb *ccb;
      int   error;

      /*
       * oflags can be checked for 'kind' of open (read-only check) - later
       * dev can be checked for a control-mode or compression open - later
       */
      UNUSED_PARAMETER(oflags);
      UNUSED_PARAMETER(dev);


      softc = (struct sa_softc *)periph->softc;

      /*
       * This should determine if something has happend since the last
       * open/mount that would invalidate the mount. We do *not* want
       * to retry this command- we just want the status. But we only
       * do this if we're mounted already- if we're not mounted,
       * we don't care about the unit read state and can instead use
       * this opportunity to attempt to reserve the tape unit.
       */
      
      if (softc->flags & SA_FLAG_TAPE_MOUNTED) {
            ccb = cam_periph_getccb(periph, 1);
            scsi_test_unit_ready(&ccb->csio, 0, sadone,
                MSG_SIMPLE_Q_TAG, SSD_FULL_SIZE, IO_TIMEOUT);
            error = cam_periph_runccb(ccb, saerror, 0, SF_NO_PRINT,
                softc->device_stats);
            QFRLS(ccb);
            if (error == ENXIO) {
                  softc->flags &= ~SA_FLAG_TAPE_MOUNTED;
                  scsi_test_unit_ready(&ccb->csio, 0, sadone,
                      MSG_SIMPLE_Q_TAG, SSD_FULL_SIZE, IO_TIMEOUT);
                  error = cam_periph_runccb(ccb, saerror, 0, SF_NO_PRINT,
                      softc->device_stats);
                  QFRLS(ccb);
            } else if (error) {
                  /*
                   * We don't need to freeze the tape because we
                   * will now attempt to rewind/load it.
                   */
                  softc->flags &= ~SA_FLAG_TAPE_MOUNTED;
                  if (CAM_DEBUGGED(periph->path, CAM_DEBUG_INFO)) {
                        xpt_print_path(periph->path);
                        printf("error %d on TUR in samount\n", error);
                  }
            }
      } else {
            error = sareservereleaseunit(periph, TRUE);
            if (error) {
                  return (error);
            }
            ccb = cam_periph_getccb(periph, 1);
            scsi_test_unit_ready(&ccb->csio, 0, sadone,
                MSG_SIMPLE_Q_TAG, SSD_FULL_SIZE, IO_TIMEOUT);
            error = cam_periph_runccb(ccb, saerror, 0, SF_NO_PRINT,
                softc->device_stats);
            QFRLS(ccb);
      }

      if ((softc->flags & SA_FLAG_TAPE_MOUNTED) == 0) {
            struct scsi_read_block_limits_data *rblim = NULL;
            int comp_enabled, comp_supported;
            u_int8_t write_protect, guessing = 0;

            /*
             * Clear out old state.
             */
            softc->flags &= ~(SA_FLAG_TAPE_WP|SA_FLAG_TAPE_WRITTEN|
                          SA_FLAG_ERR_PENDING|SA_FLAG_COMP_ENABLED|
                          SA_FLAG_COMP_SUPP|SA_FLAG_COMP_UNSUPP);
            softc->filemarks = 0;

            /*
             * *Very* first off, make sure we're loaded to BOT.
             */
            scsi_load_unload(&ccb->csio, 2, sadone, MSG_SIMPLE_Q_TAG, FALSE,
                FALSE, FALSE, 1, SSD_FULL_SIZE, REWIND_TIMEOUT);
            error = cam_periph_runccb(ccb, saerror, 0, SF_NO_PRINT,
                softc->device_stats);
            QFRLS(ccb);

            /*
             * In case this doesn't work, do a REWIND instead
             */
            if (error) {
                  scsi_rewind(&ccb->csio, 2, sadone, MSG_SIMPLE_Q_TAG,
                      FALSE, SSD_FULL_SIZE, REWIND_TIMEOUT);
                  error = cam_periph_runccb(ccb, saerror, 0, SF_NO_PRINT,
                        softc->device_stats);
                  QFRLS(ccb);
            }
            if (error) {
                  xpt_release_ccb(ccb);
                  goto exit;
            }

            /*
             * Do a dummy test read to force access to the
             * media so that the drive will really know what's
             * there. We actually don't really care what the
             * blocksize on tape is and don't expect to really
             * read a full record.
             */
            rblim = (struct  scsi_read_block_limits_data *)
                malloc(8192, M_TEMP, M_WAITOK);
            if (rblim == NULL) {
                  xpt_print_path(periph->path);
                  printf("no memory for test read\n");
                  xpt_release_ccb(ccb);
                  error = ENOMEM;
                  goto exit;
            }

            if ((softc->quirks & SA_QUIRK_NODREAD) == 0) {
                  scsi_sa_read_write(&ccb->csio, 0, sadone,
                      MSG_SIMPLE_Q_TAG, 1, FALSE, 0, 8192,
                      (void *) rblim, 8192, SSD_FULL_SIZE,
                      IO_TIMEOUT);
                  (void) cam_periph_runccb(ccb, saerror, 0, SF_NO_PRINT,
                      softc->device_stats);
                  QFRLS(ccb);
                  scsi_rewind(&ccb->csio, 1, sadone, MSG_SIMPLE_Q_TAG,
                      FALSE, SSD_FULL_SIZE, REWIND_TIMEOUT);
                  error = cam_periph_runccb(ccb, saerror, CAM_RETRY_SELTO,
                      SF_NO_PRINT | SF_RETRY_UA,
                      softc->device_stats);
                  QFRLS(ccb);
                  if (error) {
                        xpt_print_path(periph->path);
                        printf("unable to rewind after test read\n");
                        xpt_release_ccb(ccb);
                        goto exit;
                  }
            }

            /*
             * Next off, determine block limits.
             */
            scsi_read_block_limits(&ccb->csio, 5, sadone, MSG_SIMPLE_Q_TAG,
                rblim, SSD_FULL_SIZE, SCSIOP_TIMEOUT);

            error = cam_periph_runccb(ccb, saerror, CAM_RETRY_SELTO,
                SF_NO_PRINT | SF_RETRY_UA, softc->device_stats);

            QFRLS(ccb);
            xpt_release_ccb(ccb);

            if (error != 0) {
                  /*
                   * If it's less than SCSI-2, READ BLOCK LIMITS is not
                   * a MANDATORY command. Anyway- it doesn't matter-
                   * we can proceed anyway.
                   */
                  softc->blk_gran = 0;
                  softc->max_blk = ~0;
                  softc->min_blk = 0;
            } else {
                  if (softc->scsi_rev >= SCSI_REV_SPC) {
                        softc->blk_gran = RBL_GRAN(rblim);
                  } else {
                        softc->blk_gran = 0;
                  }
                  /*
                   * We take max_blk == min_blk to mean a default to
                   * fixed mode- but note that whatever we get out of
                   * sagetparams below will actually determine whether
                   * we are actually *in* fixed mode.
                   */
                  softc->max_blk = scsi_3btoul(rblim->maximum);
                  softc->min_blk = scsi_2btoul(rblim->minimum);


            }
            /*
             * Next, perform a mode sense to determine
             * current density, blocksize, compression etc.
             */
            error = sagetparams(periph, SA_PARAM_ALL,
                            &softc->media_blksize,
                            &softc->media_density,
                            &softc->media_numblks,
                            &softc->buffer_mode, &write_protect,
                            &softc->speed, &comp_supported,
                            &comp_enabled, &softc->comp_algorithm,
                            NULL);

            if (error != 0) {
                  /*
                   * We could work a little harder here. We could
                   * adjust our attempts to get information. It
                   * might be an ancient tape drive. If someone
                   * nudges us, we'll do that.
                   */
                  goto exit;
            }

            /*
             * If no quirk has determined that this is a device that is
             * preferred to be in fixed or variable mode, now is the time
             * to find out.
             */
            if ((softc->quirks & (SA_QUIRK_FIXED|SA_QUIRK_VARIABLE)) == 0) {
                  guessing = 1;
                  /*
                   * This could be expensive to find out. Luckily we
                   * only need to do this once. If we start out in
                   * 'default' mode, try and set ourselves to one
                   * of the densities that would determine a wad
                   * of other stuff. Go from highest to lowest.
                   */
                  if (softc->media_density == SCSI_DEFAULT_DENSITY) {
                        int i;
                        static u_int8_t ctry[] = {
                              SCSI_DENSITY_HALFINCH_PE,
                              SCSI_DENSITY_HALFINCH_6250C,
                              SCSI_DENSITY_HALFINCH_6250,
                              SCSI_DENSITY_HALFINCH_1600,
                              SCSI_DENSITY_HALFINCH_800,
                              SCSI_DENSITY_QIC_4GB,
                              SCSI_DENSITY_QIC_2GB,
                              SCSI_DENSITY_QIC_525_320,
                              SCSI_DENSITY_QIC_150,
                              SCSI_DENSITY_QIC_120,
                              SCSI_DENSITY_QIC_24,
                              SCSI_DENSITY_QIC_11_9TRK,
                              SCSI_DENSITY_QIC_11_4TRK,
                              SCSI_DENSITY_QIC_1320,
                              SCSI_DENSITY_QIC_3080,
                              0
                        };
                        for (i = 0; ctry[i]; i++) {
                              error = sasetparams(periph,
                                  SA_PARAM_DENSITY, 0, ctry[i],
                                  0, SF_NO_PRINT);
                              if (error == 0) {
                                    softc->media_density = ctry[i];
                                    break;
                              }
                        }
                  }
                  switch (softc->media_density) {
                  case SCSI_DENSITY_QIC_11_4TRK:
                  case SCSI_DENSITY_QIC_11_9TRK:
                  case SCSI_DENSITY_QIC_24:
                  case SCSI_DENSITY_QIC_120:
                  case SCSI_DENSITY_QIC_150:
                  case SCSI_DENSITY_QIC_525_320:
                  case SCSI_DENSITY_QIC_1320:
                  case SCSI_DENSITY_QIC_3080:
                        softc->quirks &= ~SA_QUIRK_2FM;
                        softc->quirks |= SA_QUIRK_FIXED|SA_QUIRK_1FM;
                        softc->last_media_blksize = 512;
                        break;
                  case SCSI_DENSITY_QIC_4GB:
                  case SCSI_DENSITY_QIC_2GB:
                        softc->quirks &= ~SA_QUIRK_2FM;
                        softc->quirks |= SA_QUIRK_FIXED|SA_QUIRK_1FM;
                        softc->last_media_blksize = 1024;
                        break;
                  default:
                        softc->last_media_blksize =
                            softc->media_blksize;
                        softc->quirks |= SA_QUIRK_VARIABLE;
                        break;
                  }
            }

            /*
             * If no quirk has determined that this is a device that needs
             * to have 2 Filemarks at EOD, now is the time to find out.
             */

            if ((softc->quirks & SA_QUIRK_2FM) == 0) {
                  switch (softc->media_density) {
                  case SCSI_DENSITY_HALFINCH_800:
                  case SCSI_DENSITY_HALFINCH_1600:
                  case SCSI_DENSITY_HALFINCH_6250:
                  case SCSI_DENSITY_HALFINCH_6250C:
                  case SCSI_DENSITY_HALFINCH_PE:
                        softc->quirks &= ~SA_QUIRK_1FM;
                        softc->quirks |= SA_QUIRK_2FM;
                        break;
                  default:
                        break;
                  }
            }

            /*
             * Now validate that some info we got makes sense.
             */
            if ((softc->max_blk < softc->media_blksize) ||
                (softc->min_blk > softc->media_blksize &&
                softc->media_blksize)) {
                  xpt_print_path(periph->path);
                  printf("BLOCK LIMITS (%d..%d) could not match current "
                      "block settings (%d)- adjusting\n", softc->min_blk,
                      softc->max_blk, softc->media_blksize);
                  softc->max_blk = softc->min_blk =
                      softc->media_blksize;
            }

            /*
             * Now put ourselves into the right frame of mind based
             * upon quirks...
             */
tryagain:
            /*
             * If we want to be in FIXED mode and our current blocksize
             * is not equal to our last blocksize (if nonzero), try and
             * set ourselves to this last blocksize (as the 'preferred'
             * block size).  The initial quirkmatch at registry sets the
             * initial 'last' blocksize. If, for whatever reason, this
             * 'last' blocksize is zero, set the blocksize to 512,
             * or min_blk if that's larger.
             */
            if ((softc->quirks & SA_QUIRK_FIXED) &&
                (softc->quirks & SA_QUIRK_NO_MODESEL) == 0 &&
                (softc->media_blksize != softc->last_media_blksize)) {
                  softc->media_blksize = softc->last_media_blksize;
                  if (softc->media_blksize == 0) {
                        softc->media_blksize = 512;
                        if (softc->media_blksize < softc->min_blk) {
                              softc->media_blksize = softc->min_blk;
                        }
                  }
                  error = sasetparams(periph, SA_PARAM_BLOCKSIZE,
                      softc->media_blksize, 0, 0, SF_NO_PRINT);
                  if (error) {
                        xpt_print_path(periph->path);
                        printf("unable to set fixed blocksize to %d\n",
                             softc->media_blksize);
                        goto exit;
                  }
            }

            if ((softc->quirks & SA_QUIRK_VARIABLE) && 
                (softc->media_blksize != 0)) {
                  softc->last_media_blksize = softc->media_blksize;
                  softc->media_blksize = 0;
                  error = sasetparams(periph, SA_PARAM_BLOCKSIZE,
                      0, 0, 0, SF_NO_PRINT);
                  if (error) {
                        /*
                         * If this fails and we were guessing, just
                         * assume that we got it wrong and go try
                         * fixed block mode. Don't even check against
                         * density code at this point.
                         */
                        if (guessing) {
                              softc->quirks &= ~SA_QUIRK_VARIABLE;
                              softc->quirks |= SA_QUIRK_FIXED;
                              if (softc->last_media_blksize == 0)
                                    softc->last_media_blksize = 512;
                              goto tryagain;
                        }
                        xpt_print_path(periph->path);
                        printf("unable to set variable blocksize\n");
                        goto exit;
                  }
            }

            /*
             * Now that we have the current block size,
             * set up some parameters for sastart's usage.
             */
            if (softc->media_blksize) {
                  softc->flags |= SA_FLAG_FIXED;
                  if (powerof2(softc->media_blksize)) {
                        softc->blk_shift =
                            ffs(softc->media_blksize) - 1;
                        softc->blk_mask = softc->media_blksize - 1;
                  } else {
                        softc->blk_mask = ~0;
                        softc->blk_shift = 0;
                  }
            } else {
                  /*
                   * The SCSI-3 spec allows 0 to mean "unspecified".
                   * The SCSI-1 spec allows 0 to mean 'infinite'.
                   *
                   * Either works here.
                   */
                  if (softc->max_blk == 0) {
                        softc->max_blk = ~0;
                  }
                  softc->blk_shift = 0;
                  if (softc->blk_gran != 0) {
                        softc->blk_mask = softc->blk_gran - 1;
                  } else {
                        softc->blk_mask = 0;
                  }
            }

            if (write_protect) 
                  softc->flags |= SA_FLAG_TAPE_WP;

            if (comp_supported) {
                  if (softc->saved_comp_algorithm == 0)
                        softc->saved_comp_algorithm =
                            softc->comp_algorithm;
                  softc->flags |= SA_FLAG_COMP_SUPP;
                  if (comp_enabled)
                        softc->flags |= SA_FLAG_COMP_ENABLED;
            } else
                  softc->flags |= SA_FLAG_COMP_UNSUPP;

            if ((softc->buffer_mode == SMH_SA_BUF_MODE_NOBUF) &&
                (softc->quirks & SA_QUIRK_NO_MODESEL) == 0) {
                  error = sasetparams(periph, SA_PARAM_BUFF_MODE, 0,
                      0, 0, SF_NO_PRINT);
                  if (error == 0) {
                        softc->buffer_mode = SMH_SA_BUF_MODE_SIBUF;
                  } else {
                        xpt_print_path(periph->path);
                        printf("unable to set buffered mode\n");
                  }
                  error = 0;  /* not an error */
            }


            if (error == 0) {
                  softc->flags |= SA_FLAG_TAPE_MOUNTED;
            }
exit:
            if (rblim != NULL)
                  free(rblim, M_TEMP);

            if (error != 0) {
                  softc->dsreg = MTIO_DSREG_NIL;
            } else {
                  softc->fileno = softc->blkno = 0;
                  softc->dsreg = MTIO_DSREG_REST;
            }
#ifdef      SA_1FM_AT_EOD
            if ((softc->quirks & SA_QUIRK_2FM) == 0)
                  softc->quirks |= SA_QUIRK_1FM;
#else
            if ((softc->quirks & SA_QUIRK_1FM) == 0)
                  softc->quirks |= SA_QUIRK_2FM;
#endif
      } else
            xpt_release_ccb(ccb);

      /*
       * If we return an error, we're not mounted any more,
       * so release any device reservation.
       */
      if (error != 0) {
            (void) sareservereleaseunit(periph, FALSE);
      } else {
            /*
             * Clear I/O residual.
             */
            softc->last_io_resid = 0;
            softc->last_ctl_resid = 0;
      }
      return (error);
}

/*
 * How many filemarks do we need to write if we were to terminate the
 * tape session right now? Note that this can be a negative number
 */

static int
samarkswanted(struct cam_periph *periph)
{
      int   markswanted;
      struct      sa_softc *softc;

      softc = (struct sa_softc *)periph->softc;
      markswanted = 0;
      if ((softc->flags & SA_FLAG_TAPE_WRITTEN) != 0) {
            markswanted++;
            if (softc->quirks & SA_QUIRK_2FM)
                  markswanted++;
      }
      markswanted -= softc->filemarks;
      return (markswanted);
}

static int
sacheckeod(struct cam_periph *periph)
{
      int   error;
      int   markswanted;

      markswanted = samarkswanted(periph);

      if (markswanted > 0) {
            error = sawritefilemarks(periph, markswanted, FALSE);
      } else {
            error = 0;
      }
      return (error);
}

static int
saerror(union ccb *ccb, u_int32_t cflgs, u_int32_t sflgs)
{
      static const char *toobig =
          "%d-byte tape record bigger than supplied buffer\n";
      struct      cam_periph *periph;
      struct      sa_softc *softc;
      struct      ccb_scsiio *csio;
      struct      scsi_sense_data *sense;
      u_int32_t resid = 0;
      int32_t     info = 0;
      cam_status status;
      int error_code, sense_key, asc, ascq, error, aqvalid;

      periph = xpt_path_periph(ccb->ccb_h.path);
      softc = (struct sa_softc *)periph->softc;
      csio = &ccb->csio;
      sense = &csio->sense_data;
      scsi_extract_sense(sense, &error_code, &sense_key, &asc, &ascq);
      aqvalid = sense->extra_len >= 6;
      error = 0;

      status = csio->ccb_h.status & CAM_STATUS_MASK;

      /*
       * Calculate/latch up, any residuals... We do this in a funny 2-step
       * so we can print stuff here if we have CAM_DEBUG enabled for this
       * unit.
       */
      if (status == CAM_SCSI_STATUS_ERROR) {
            if ((sense->error_code & SSD_ERRCODE_VALID) != 0) {
                  info = (int32_t) scsi_4btoul(sense->info);
                  resid = info;
                  if ((softc->flags & SA_FLAG_FIXED) != 0)
                        resid *= softc->media_blksize;
            } else {
                  resid = csio->dxfer_len;
                  info = resid;
                  if ((softc->flags & SA_FLAG_FIXED) != 0) {
                        if (softc->media_blksize)
                              info /= softc->media_blksize;
                  }
            }
            if (CCB_Type(csio) == SA_CCB_BUFFER_IO) {
                  bcopy((caddr_t) sense, (caddr_t) &softc->last_io_sense,
                      sizeof (struct scsi_sense_data));
                  bcopy(csio->cdb_io.cdb_bytes, softc->last_io_cdb,
                      (int) csio->cdb_len);
                  softc->last_io_resid = resid;
                  softc->last_resid_was_io = 1;
            } else {
                  bcopy((caddr_t) sense, (caddr_t) &softc->last_ctl_sense,
                      sizeof (struct scsi_sense_data));
                  bcopy(csio->cdb_io.cdb_bytes, softc->last_ctl_cdb,
                      (int) csio->cdb_len);
                  softc->last_ctl_resid = resid;
                  softc->last_resid_was_io = 0;
            }
            CAM_DEBUG(periph->path, CAM_DEBUG_INFO, ("CDB[0]=0x%x Key 0x%x "
                "ASC/ASCQ 0x%x/0x%x CAM STATUS 0x%x flags 0x%x resid %d "
                "dxfer_len %d\n", csio->cdb_io.cdb_bytes[0] & 0xff,
                sense_key, asc, ascq, status,
                sense->flags & ~SSD_KEY_RESERVED, resid, csio->dxfer_len));
      } else {
            CAM_DEBUG(periph->path, CAM_DEBUG_INFO,
                ("Cam Status 0x%x\n", status));
      }

      switch (status) {
      case CAM_REQ_CMP:
            return (0);
      case CAM_SCSI_STATUS_ERROR:
            /*
             * If a read/write command, we handle it here.
             */
            if (CCB_Type(csio) != SA_CCB_WAITING) {
                  break;
            }
            /*
             * If this was just EOM/EOP, Filemark, Setmark or ILI detected
             * on a non read/write command, we assume it's not an error
             * and propagate the residule and return.
             */
            if ((aqvalid && asc == 0 && ascq > 0 && ascq <= 5) ||
                (aqvalid == 0 && sense_key == SSD_KEY_NO_SENSE)) {
                  csio->resid = resid;
                  QFRLS(ccb);
                  return (0);
            }
            /*
             * Otherwise, we let the common code handle this.
             */
            return (cam_periph_error(ccb, cflgs, sflgs, &softc->saved_ccb));

      /*
       * XXX: To Be Fixed
       * We cannot depend upon CAM honoring retry counts for these.
       */
      case CAM_SCSI_BUS_RESET:
      case CAM_BDR_SENT:
            if (ccb->ccb_h.retry_count <= 0) {
                  return (EIO);
            }
            /* FALLTHROUGH */
      default:
            return (cam_periph_error(ccb, cflgs, sflgs, &softc->saved_ccb));
      }

      /*
       * Handle filemark, end of tape, mismatched record sizes....
       * From this point out, we're only handling read/write cases.
       * Handle writes && reads differently.
       */

      if (csio->cdb_io.cdb_bytes[0] == SA_WRITE) {
            if (sense_key == SSD_KEY_VOLUME_OVERFLOW) {
                  csio->resid = resid;
                  error = ENOSPC;
            } else if (sense->flags & SSD_EOM) {
                  softc->flags |= SA_FLAG_EOM_PENDING;
                  /*
                   * Grotesque as it seems, the few times
                   * I've actually seen a non-zero resid,
                   * the tape drive actually lied and had
                   * written all the data!.
                   */
                  csio->resid = 0;
            }
      } else {
            csio->resid = resid;
            if (sense_key == SSD_KEY_BLANK_CHECK) {
                  if (softc->quirks & SA_QUIRK_1FM) {
                        error = 0;
                        softc->flags |= SA_FLAG_EOM_PENDING;
                  } else {
                        error = EIO;
                  }
            } else if (sense->flags & SSD_FILEMARK) {
                  if (softc->flags & SA_FLAG_FIXED) {
                        error = -1;
                        softc->flags |= SA_FLAG_EOF_PENDING;
                  }
                  /*
                   * Unconditionally, if we detected a filemark on a read,
                   * mark that we've run moved a file ahead.
                   */
                  if (softc->fileno != (daddr_t) -1) {
                        softc->fileno++;
                        softc->blkno = 0;
                        csio->ccb_h.ccb_pflags |= SA_POSITION_UPDATED;
                  }
            }
      }

      /*
       * Incorrect Length usually applies to read, but can apply to writes.
       */
      if (error == 0 && (sense->flags & SSD_ILI)) {
            if (info < 0) {
                  xpt_print_path(csio->ccb_h.path);
                  printf(toobig, csio->dxfer_len - info);
                  csio->resid = csio->dxfer_len;
                  error = EIO;
            } else {
                  csio->resid = resid;
                  if (softc->flags & SA_FLAG_FIXED) {
                        softc->flags |= SA_FLAG_EIO_PENDING;
                  }
                  /*
                   * Bump the block number if we hadn't seen a filemark.
                   * Do this independent of errors (we've moved anyway).
                   */
                  if ((sense->flags & SSD_FILEMARK) == 0) {
                        if (softc->blkno != (daddr_t) -1) {
                              softc->blkno++;
                              csio->ccb_h.ccb_pflags |=
                                 SA_POSITION_UPDATED;
                        }
                  }
            }
      }

      if (error <= 0) {
            /*
             * Unfreeze the queue if frozen as we're not returning anything
             * to our waiters that would indicate an I/O error has occurred
             * (yet).
             */
            QFRLS(ccb);
            error = 0;
      }
      return (error);
}

static int
sagetparams(struct cam_periph *periph, sa_params params_to_get,
          u_int32_t *blocksize, u_int8_t *density, u_int32_t *numblocks,
          int *buff_mode, u_int8_t *write_protect, u_int8_t *speed,
          int *comp_supported, int *comp_enabled, u_int32_t *comp_algorithm,
          sa_comp_t *tcs)
{
      union ccb *ccb;
      void *mode_buffer;
      struct scsi_mode_header_6 *mode_hdr;
      struct scsi_mode_blk_desc *mode_blk;
      int mode_buffer_len;
      struct sa_softc *softc;
      u_int8_t cpage;
      int error;
      cam_status status;

      softc = (struct sa_softc *)periph->softc;
      ccb = cam_periph_getccb(periph, 1);
      if (softc->quirks & SA_QUIRK_NO_CPAGE)
            cpage = SA_DEVICE_CONFIGURATION_PAGE;
      else
            cpage = SA_DATA_COMPRESSION_PAGE;

retry:
      mode_buffer_len = sizeof(*mode_hdr) + sizeof(*mode_blk);

      if (params_to_get & SA_PARAM_COMPRESSION) {
            if (softc->quirks & SA_QUIRK_NOCOMP) {
                  *comp_supported = FALSE;
                  params_to_get &= ~SA_PARAM_COMPRESSION;
            } else
                  mode_buffer_len += sizeof (sa_comp_t);
      }

      mode_buffer = malloc(mode_buffer_len, M_TEMP, M_WAITOK | M_ZERO);
      mode_hdr = (struct scsi_mode_header_6 *)mode_buffer;
      mode_blk = (struct scsi_mode_blk_desc *)&mode_hdr[1];

      /* it is safe to retry this */
      scsi_mode_sense(&ccb->csio, 5, sadone, MSG_SIMPLE_Q_TAG, FALSE,
          SMS_PAGE_CTRL_CURRENT, (params_to_get & SA_PARAM_COMPRESSION) ?
          cpage : SMS_VENDOR_SPECIFIC_PAGE, mode_buffer, mode_buffer_len,
          SSD_FULL_SIZE, SCSIOP_TIMEOUT);

      error = cam_periph_runccb(ccb, saerror, 0, SF_NO_PRINT,
          softc->device_stats);
      QFRLS(ccb);

      status = ccb->ccb_h.status & CAM_STATUS_MASK;

      if (error == EINVAL && (params_to_get & SA_PARAM_COMPRESSION) != 0) {
            /*
             * Hmm. Let's see if we can try another page...
             * If we've already done that, give up on compression
             * for this device and remember this for the future
             * and attempt the request without asking for compression
             * info.
             */
            if (cpage == SA_DATA_COMPRESSION_PAGE) {
                  cpage = SA_DEVICE_CONFIGURATION_PAGE;
                  goto retry;
            }
            softc->quirks |= SA_QUIRK_NOCOMP;
            free(mode_buffer, M_TEMP);
            goto retry;
      } else if (status == CAM_SCSI_STATUS_ERROR) {
            /* Tell the user about the fatal error. */
            scsi_sense_print(&ccb->csio);
            goto sagetparamsexit;
      }

      /*
       * If the user only wants the compression information, and
       * the device doesn't send back the block descriptor, it's
       * no big deal.  If the user wants more than just
       * compression, though, and the device doesn't pass back the
       * block descriptor, we need to send another mode sense to
       * get the block descriptor.
       */
      if ((mode_hdr->blk_desc_len == 0) &&
          (params_to_get & SA_PARAM_COMPRESSION) &&
          (params_to_get & ~(SA_PARAM_COMPRESSION))) {

            /*
             * Decrease the mode buffer length by the size of
             * the compression page, to make sure the data
             * there doesn't get overwritten.
             */
            mode_buffer_len -= sizeof (sa_comp_t);

            /*
             * Now move the compression page that we presumably
             * got back down the memory chunk a little bit so
             * it doesn't get spammed.
             */
            bcopy(&mode_hdr[0], &mode_hdr[1], sizeof (sa_comp_t));
            bzero(&mode_hdr[0], sizeof (mode_hdr[0]));

            /*
             * Now, we issue another mode sense and just ask
             * for the block descriptor, etc.
             */

            scsi_mode_sense(&ccb->csio, 2, sadone, MSG_SIMPLE_Q_TAG, FALSE,
                SMS_PAGE_CTRL_CURRENT, SMS_VENDOR_SPECIFIC_PAGE,
                mode_buffer, mode_buffer_len, SSD_FULL_SIZE,
                SCSIOP_TIMEOUT);

            error = cam_periph_runccb(ccb, saerror, 0, SF_NO_PRINT,
                softc->device_stats);
            QFRLS(ccb);

            if (error != 0)
                  goto sagetparamsexit;
      }

      if (params_to_get & SA_PARAM_BLOCKSIZE)
            *blocksize = scsi_3btoul(mode_blk->blklen);

      if (params_to_get & SA_PARAM_NUMBLOCKS)
            *numblocks = scsi_3btoul(mode_blk->nblocks);

      if (params_to_get & SA_PARAM_BUFF_MODE)
            *buff_mode = mode_hdr->dev_spec & SMH_SA_BUF_MODE_MASK;

      if (params_to_get & SA_PARAM_DENSITY)
            *density = mode_blk->density;

      if (params_to_get & SA_PARAM_WP)
            *write_protect = (mode_hdr->dev_spec & SMH_SA_WP)? TRUE : FALSE;

      if (params_to_get & SA_PARAM_SPEED)
            *speed = mode_hdr->dev_spec & SMH_SA_SPEED_MASK;

      if (params_to_get & SA_PARAM_COMPRESSION) {
            sa_comp_t *ntcs = (sa_comp_t *) &mode_blk[1];
            if (cpage == SA_DATA_COMPRESSION_PAGE) {
                  struct scsi_data_compression_page *cp = &ntcs->dcomp;
                  *comp_supported =
                      (cp->dce_and_dcc & SA_DCP_DCC)? TRUE : FALSE;
                  *comp_enabled =
                      (cp->dce_and_dcc & SA_DCP_DCE)? TRUE : FALSE;
                  *comp_algorithm = scsi_4btoul(cp->comp_algorithm);
            } else {
                  struct scsi_dev_conf_page *cp = &ntcs->dconf;
                  /*
                   * We don't really know whether this device supports
                   * Data Compression if the the algorithm field is
                   * zero. Just say we do.
                   */
                  *comp_supported = TRUE;
                  *comp_enabled =
                      (cp->sel_comp_alg != SA_COMP_NONE)? TRUE : FALSE;
                  *comp_algorithm = cp->sel_comp_alg;
            }
            if (tcs != NULL)
                  bcopy(ntcs, tcs, sizeof (sa_comp_t));
      }

      if (CAM_DEBUGGED(periph->path, CAM_DEBUG_INFO)) {
            int idx;
            char *xyz = mode_buffer;
            xpt_print_path(periph->path);
            printf("Mode Sense Data=");
            for (idx = 0; idx < mode_buffer_len; idx++)
                  printf(" 0x%02x", xyz[idx] & 0xff);
            printf("\n");
      }

sagetparamsexit:

      xpt_release_ccb(ccb);
      free(mode_buffer, M_TEMP);
      return (error);
}

/*
 * The purpose of this function is to set one of four different parameters
 * for a tape drive:
 *    - blocksize
 *    - density
 *    - compression / compression algorithm
 *    - buffering mode
 *
 * The assumption is that this will be called from saioctl(), and therefore
 * from a process context.  Thus the waiting malloc calls below.  If that
 * assumption ever changes, the malloc calls should be changed to be
 * NOWAIT mallocs.
 *
 * Any or all of the four parameters may be set when this function is
 * called.  It should handle setting more than one parameter at once.
 */
static int
sasetparams(struct cam_periph *periph, sa_params params_to_set,
          u_int32_t blocksize, u_int8_t density, u_int32_t calg,
          u_int32_t sense_flags)
{
      struct sa_softc *softc;
      u_int32_t current_blocksize;
      u_int32_t current_calg;
      u_int8_t current_density;
      u_int8_t current_speed;
      int comp_enabled, comp_supported;
      void *mode_buffer;
      int mode_buffer_len;
      struct scsi_mode_header_6 *mode_hdr;
      struct scsi_mode_blk_desc *mode_blk;
      sa_comp_t *ccomp, *cpage;
      int buff_mode;
      union ccb *ccb = NULL;
      int error;

      softc = (struct sa_softc *)periph->softc;

      ccomp = malloc(sizeof (sa_comp_t), M_TEMP, M_WAITOK);

      /*
       * Since it doesn't make sense to set the number of blocks, or
       * write protection, we won't try to get the current value.  We
       * always want to get the blocksize, so we can set it back to the
       * proper value.
       */
      error = sagetparams(periph,
          params_to_set | SA_PARAM_BLOCKSIZE | SA_PARAM_SPEED,
          &current_blocksize, &current_density, NULL, &buff_mode, NULL,
          &current_speed, &comp_supported, &comp_enabled,
          &current_calg, ccomp);

      if (error != 0) {
            free(ccomp, M_TEMP);
            return (error);
      }

      mode_buffer_len = sizeof(*mode_hdr) + sizeof(*mode_blk);
      if (params_to_set & SA_PARAM_COMPRESSION)
            mode_buffer_len += sizeof (sa_comp_t);

      mode_buffer = malloc(mode_buffer_len, M_TEMP, M_WAITOK | M_ZERO);

      mode_hdr = (struct scsi_mode_header_6 *)mode_buffer;
      mode_blk = (struct scsi_mode_blk_desc *)&mode_hdr[1];

      ccb = cam_periph_getccb(periph, 1);

retry:

      if (params_to_set & SA_PARAM_COMPRESSION) {
            if (mode_blk) {
                  cpage = (sa_comp_t *)&mode_blk[1];
            } else {
                  cpage = (sa_comp_t *)&mode_hdr[1];
            }
            bcopy(ccomp, cpage, sizeof (sa_comp_t));
            cpage->hdr.pagecode &= ~0x80;
      } else
            cpage = NULL;

      /*
       * If the caller wants us to set the blocksize, use the one they
       * pass in.  Otherwise, use the blocksize we got back from the
       * mode select above.
       */
      if (mode_blk) {
            if (params_to_set & SA_PARAM_BLOCKSIZE)
                  scsi_ulto3b(blocksize, mode_blk->blklen);
            else
                  scsi_ulto3b(current_blocksize, mode_blk->blklen);

            /*
             * Set density if requested, else preserve old density.
             * SCSI_SAME_DENSITY only applies to SCSI-2 or better
             * devices, else density we've latched up in our softc.
             */
            if (params_to_set & SA_PARAM_DENSITY) {
                  mode_blk->density = density;
            } else if (softc->scsi_rev > SCSI_REV_CCS) {
                  mode_blk->density = SCSI_SAME_DENSITY;
            } else {
                  mode_blk->density = softc->media_density;
            }
      }

      /*
       * For mode selects, these two fields must be zero.
       */
      mode_hdr->data_length = 0;
      mode_hdr->medium_type = 0;

      /* set the speed to the current value */
      mode_hdr->dev_spec = current_speed;

      /* if set, set single-initiator buffering mode */
      if (softc->buffer_mode == SMH_SA_BUF_MODE_SIBUF) {
            mode_hdr->dev_spec |= SMH_SA_BUF_MODE_SIBUF;
      }

      if (mode_blk)
            mode_hdr->blk_desc_len = sizeof(struct scsi_mode_blk_desc);
      else
            mode_hdr->blk_desc_len = 0;

      /*
       * First, if the user wants us to set the compression algorithm or
       * just turn compression on, check to make sure that this drive
       * supports compression.
       */
      if (params_to_set & SA_PARAM_COMPRESSION) {
            /*
             * If the compression algorithm is 0, disable compression.
             * If the compression algorithm is non-zero, enable
             * compression and set the compression type to the
             * specified compression algorithm, unless the algorithm is
             * MT_COMP_ENABLE.  In that case, we look at the
             * compression algorithm that is currently set and if it is
             * non-zero, we leave it as-is.  If it is zero, and we have
             * saved a compression algorithm from a time when
             * compression was enabled before, set the compression to
             * the saved value.
             */
            switch (ccomp->hdr.pagecode & ~0x80) {
            case SA_DEVICE_CONFIGURATION_PAGE:
            {
                  struct scsi_dev_conf_page *dcp = &cpage->dconf;
                  if (calg == 0) {
                        dcp->sel_comp_alg = SA_COMP_NONE;
                        break;
                  }
                  if (calg != MT_COMP_ENABLE) {
                        dcp->sel_comp_alg = calg;
                  } else if (dcp->sel_comp_alg == SA_COMP_NONE &&
                      softc->saved_comp_algorithm != 0) {
                        dcp->sel_comp_alg = softc->saved_comp_algorithm;
                  }
                  break;
            }
            case SA_DATA_COMPRESSION_PAGE:
            if (ccomp->dcomp.dce_and_dcc & SA_DCP_DCC) {
                  struct scsi_data_compression_page *dcp = &cpage->dcomp;
                  if (calg == 0) {
                        /*
                         * Disable compression, but leave the
                         * decompression and the capability bit
                         * alone.
                         */
                        dcp->dce_and_dcc = SA_DCP_DCC;
                        dcp->dde_and_red |= SA_DCP_DDE;
                        break;
                  }
                  /* enable compression && decompression */
                  dcp->dce_and_dcc = SA_DCP_DCE | SA_DCP_DCC;
                  dcp->dde_and_red |= SA_DCP_DDE;
                  /*
                   * If there, use compression algorithm from caller.
                   * Otherwise, if there's a saved compression algorithm
                   * and there is no current algorithm, use the saved
                   * algorithm. Else parrot back what we got and hope
                   * for the best.
                   */
                  if (calg != MT_COMP_ENABLE) {
                        scsi_ulto4b(calg, dcp->comp_algorithm);
                        scsi_ulto4b(calg, dcp->decomp_algorithm);
                  } else if (scsi_4btoul(dcp->comp_algorithm) == 0 &&
                      softc->saved_comp_algorithm != 0) {
                        scsi_ulto4b(softc->saved_comp_algorithm,
                            dcp->comp_algorithm);
                        scsi_ulto4b(softc->saved_comp_algorithm,
                            dcp->decomp_algorithm);
                  }
                  break;
            }
            /*
             * Compression does not appear to be supported-
             * at least via the DATA COMPRESSION page. It
             * would be too much to ask us to believe that
             * the page itself is supported, but incorrectly
             * reports an ability to manipulate data compression,
             * so we'll assume that this device doesn't support
             * compression. We can just fall through for that.
             */
            /* FALLTHROUGH */
            default:
                  /*
                   * The drive doesn't seem to support compression,
                   * so turn off the set compression bit.
                   */
                  params_to_set &= ~SA_PARAM_COMPRESSION;
                  xpt_print_path(periph->path);
                  printf("device does not seem to support compression\n");

                  /*
                   * If that was the only thing the user wanted us to set,
                   * clean up allocated resources and return with
                   * 'operation not supported'.
                   */
                  if (params_to_set == SA_PARAM_NONE) {
                        free(mode_buffer, M_TEMP);
                        xpt_release_ccb(ccb);
                        return (ENODEV);
                  }
            
                  /*
                   * That wasn't the only thing the user wanted us to set.
                   * So, decrease the stated mode buffer length by the
                   * size of the compression mode page.
                   */
                  mode_buffer_len -= sizeof(sa_comp_t);
            }
      }

      /* It is safe to retry this operation */
      scsi_mode_select(&ccb->csio, 5, sadone, MSG_SIMPLE_Q_TAG,
          (params_to_set & SA_PARAM_COMPRESSION)? TRUE : FALSE,
          FALSE, mode_buffer, mode_buffer_len, SSD_FULL_SIZE, SCSIOP_TIMEOUT);

      error = cam_periph_runccb(ccb, saerror, 0,
          sense_flags, softc->device_stats);
      QFRLS(ccb);

      if (CAM_DEBUGGED(periph->path, CAM_DEBUG_INFO)) {
            int idx;
            char *xyz = mode_buffer;
            xpt_print_path(periph->path);
            printf("Err%d, Mode Select Data=", error);
            for (idx = 0; idx < mode_buffer_len; idx++)
                  printf(" 0x%02x", xyz[idx] & 0xff);
            printf("\n");
      }


      if (error) {
            /*
             * If we can, try without setting density/blocksize.
             */
            if (mode_blk) {
                  if ((params_to_set &
                      (SA_PARAM_DENSITY|SA_PARAM_BLOCKSIZE)) == 0) {
                        mode_blk = NULL;
                        goto retry;
                  }
            } else {
                  mode_blk = (struct scsi_mode_blk_desc *)&mode_hdr[1];
                  cpage = (sa_comp_t *)&mode_blk[1];
            }

            /*
             * If we were setting the blocksize, and that failed, we
             * want to set it to its original value.  If we weren't
             * setting the blocksize, we don't want to change it.
             */
            scsi_ulto3b(current_blocksize, mode_blk->blklen);

            /*
             * Set density if requested, else preserve old density.
             * SCSI_SAME_DENSITY only applies to SCSI-2 or better
             * devices, else density we've latched up in our softc.
             */
            if (params_to_set & SA_PARAM_DENSITY) {
                  mode_blk->density = current_density;
            } else if (softc->scsi_rev > SCSI_REV_CCS) {
                  mode_blk->density = SCSI_SAME_DENSITY;
            } else {
                  mode_blk->density = softc->media_density;
            }

            if (params_to_set & SA_PARAM_COMPRESSION)
                  bcopy(ccomp, cpage, sizeof (sa_comp_t));

            /*
             * The retry count is the only CCB field that might have been
             * changed that we care about, so reset it back to 1.
             */
            ccb->ccb_h.retry_count = 1;
            cam_periph_runccb(ccb, saerror, 0, sense_flags,
                softc->device_stats);
            QFRLS(ccb);
      }

      xpt_release_ccb(ccb);

      if (ccomp != NULL)
            free(ccomp, M_TEMP);

      if (params_to_set & SA_PARAM_COMPRESSION) {
            if (error) {
                  softc->flags &= ~SA_FLAG_COMP_ENABLED;
                  /*
                   * Even if we get an error setting compression,
                   * do not say that we don't support it. We could
                   * have been wrong, or it may be media specific.
                   *    softc->flags &= ~SA_FLAG_COMP_SUPP;
                   */
                  softc->saved_comp_algorithm = softc->comp_algorithm;
                  softc->comp_algorithm = 0;
            } else {
                  softc->flags |= SA_FLAG_COMP_ENABLED;
                  softc->comp_algorithm = calg;
            }
      }

      free(mode_buffer, M_TEMP);
      return (error);
}

static void
saprevent(struct cam_periph *periph, int action)
{
      struct      sa_softc *softc;
      union ccb *ccb;         
      int   error, sf;
            
      softc = (struct sa_softc *)periph->softc;

      if ((action == PR_ALLOW) && (softc->flags & SA_FLAG_TAPE_LOCKED) == 0)
            return;
      if ((action == PR_PREVENT) && (softc->flags & SA_FLAG_TAPE_LOCKED) != 0)
            return;

      /*
       * We can be quiet about illegal requests.
       */
      if (CAM_DEBUGGED(periph->path, CAM_DEBUG_INFO)) {
            sf = 0;
      } else
            sf = SF_QUIET_IR;

      ccb = cam_periph_getccb(periph, 1);

      /* It is safe to retry this operation */
      scsi_prevent(&ccb->csio, 5, sadone, MSG_SIMPLE_Q_TAG, action,
          SSD_FULL_SIZE, SCSIOP_TIMEOUT);

      error = cam_periph_runccb(ccb, saerror, 0, sf, softc->device_stats);
      QFRLS(ccb);
      if (error == 0) {
            if (action == PR_ALLOW)
                  softc->flags &= ~SA_FLAG_TAPE_LOCKED;
            else
                  softc->flags |= SA_FLAG_TAPE_LOCKED;
      }

      xpt_release_ccb(ccb);
}

static int
sarewind(struct cam_periph *periph)
{
      union ccb *ccb;
      struct      sa_softc *softc;
      int   error;
            
      softc = (struct sa_softc *)periph->softc;

      ccb = cam_periph_getccb(periph, 1);

      /* It is safe to retry this operation */
      scsi_rewind(&ccb->csio, 2, sadone, MSG_SIMPLE_Q_TAG, FALSE,
          SSD_FULL_SIZE, REWIND_TIMEOUT);

      softc->dsreg = MTIO_DSREG_REW;
      error = cam_periph_runccb(ccb, saerror, 0, 0, softc->device_stats);
      softc->dsreg = MTIO_DSREG_REST;

      if ((ccb->ccb_h.status & CAM_DEV_QFRZN) != 0)
            cam_release_devq(ccb->ccb_h.path, 0, 0, 0, FALSE);

      xpt_release_ccb(ccb);
      if (error == 0)
            softc->fileno = softc->blkno = (daddr_t) 0;
      else
            softc->fileno = softc->blkno = (daddr_t) -1;
      return (error);
}

static int
saspace(struct cam_periph *periph, int count, scsi_space_code code)
{
      union ccb *ccb;
      struct      sa_softc *softc;
      int   error;
            
      softc = (struct sa_softc *)periph->softc;

      ccb = cam_periph_getccb(periph, 1);

      /* This cannot be retried */

      scsi_space(&ccb->csio, 0, sadone, MSG_SIMPLE_Q_TAG, code, count,
          SSD_FULL_SIZE, SPACE_TIMEOUT);

      /*
       * Clear residual because we will be using it.
       */
      softc->last_ctl_resid = 0;

      softc->dsreg = (count < 0)? MTIO_DSREG_REV : MTIO_DSREG_FWD;
      error = cam_periph_runccb(ccb, saerror, 0, 0, softc->device_stats);
      softc->dsreg = MTIO_DSREG_REST;

      if ((ccb->ccb_h.status & CAM_DEV_QFRZN) != 0)
            cam_release_devq(ccb->ccb_h.path, 0, 0, 0, FALSE);

      xpt_release_ccb(ccb);

      /*
       * If a spacing operation has failed, we need to invalidate
       * this mount.
       *
       * If the spacing operation was setmarks or to end of recorded data,
       * we no longer know our relative position.
       *
       * If the spacing operations was spacing files in reverse, we
       * take account of the residual, but still check against less
       * than zero- if we've gone negative, we must have hit BOT.
       *
       * If the spacing operations was spacing records in reverse and
       * we have a residual, we've either hit BOT or hit a filemark.
       * In the former case, we know our new record number (0). In
       * the latter case, we have absolutely no idea what the real
       * record number is- we've stopped between the end of the last
       * record in the previous file and the filemark that stopped
       * our spacing backwards.
       */
      if (error) {
            softc->fileno = softc->blkno = (daddr_t) -1;
      } else if (code == SS_SETMARKS || code == SS_EOD) {
            softc->fileno = softc->blkno = (daddr_t) -1;
      } else if (code == SS_FILEMARKS && softc->fileno != (daddr_t) -1) {
            softc->fileno += (count - softc->last_ctl_resid);
            if (softc->fileno < 0)  /* we must of hit BOT */
                  softc->fileno = 0;
            softc->blkno = 0;
      } else if (code == SS_BLOCKS && softc->blkno != (daddr_t) -1) {
            softc->blkno += (count - softc->last_ctl_resid);
            if (count < 0) {
                  if (softc->last_ctl_resid || softc->blkno < 0) {
                        if (softc->fileno == 0) {
                              softc->blkno = 0;
                        } else {
                              softc->blkno = (daddr_t) -1;
                        }
                  }
            }
      }
      return (error);
}

static int
sawritefilemarks(struct cam_periph *periph, int nmarks, int setmarks)
{
      union ccb *ccb;
      struct      sa_softc *softc;
      int   error, nwm = 0;

      softc = (struct sa_softc *)periph->softc;
      if (softc->open_rdonly)
            return (EBADF);

      ccb = cam_periph_getccb(periph, 1);
      /*
       * Clear residual because we will be using it.
       */
      softc->last_ctl_resid = 0;

      softc->dsreg = MTIO_DSREG_FMK;
      /* this *must* not be retried */
      scsi_write_filemarks(&ccb->csio, 0, sadone, MSG_SIMPLE_Q_TAG,
          FALSE, setmarks, nmarks, SSD_FULL_SIZE, IO_TIMEOUT);
      softc->dsreg = MTIO_DSREG_REST;


      error = cam_periph_runccb(ccb, saerror, 0, 0, softc->device_stats);

      if ((ccb->ccb_h.status & CAM_DEV_QFRZN) != 0)
            cam_release_devq(ccb->ccb_h.path, 0, 0, 0, FALSE);

      if (error == 0 && nmarks) {
            struct sa_softc *softc = (struct sa_softc *)periph->softc;
            nwm = nmarks - softc->last_ctl_resid;
            softc->filemarks += nwm;
      }

      xpt_release_ccb(ccb);

      /*
       * Update relative positions (if we're doing that).
       */
      if (error) {
            softc->fileno = softc->blkno = (daddr_t) -1;
      } else if (softc->fileno != (daddr_t) -1) {
            softc->fileno += nwm;
            softc->blkno = 0;
      }
      return (error);
}

static int
sardpos(struct cam_periph *periph, int hard, u_int32_t *blkptr)
{
      struct scsi_tape_position_data loc;
      union ccb *ccb;
      struct sa_softc *softc = (struct sa_softc *)periph->softc;
      int error;

      /*
       * We try and flush any buffered writes here if we were writing
       * and we're trying to get hardware block position. It eats
       * up performance substantially, but I'm wary of drive firmware.
       *
       * I think that *logical* block position is probably okay-
       * but hardware block position might have to wait for data
       * to hit media to be valid. Caveat Emptor.
       */

      if (hard && (softc->flags & SA_FLAG_TAPE_WRITTEN)) {
            error = sawritefilemarks(periph, 0, 0);
            if (error && error != EACCES)
                  return (error);
      }

      ccb = cam_periph_getccb(periph, 1);
      scsi_read_position(&ccb->csio, 1, sadone, MSG_SIMPLE_Q_TAG,
          hard, &loc, SSD_FULL_SIZE, SCSIOP_TIMEOUT);
      softc->dsreg = MTIO_DSREG_RBSY;
      error = cam_periph_runccb(ccb, saerror, 0, 0, softc->device_stats);
      softc->dsreg = MTIO_DSREG_REST;
      if ((ccb->ccb_h.status & CAM_DEV_QFRZN) != 0)
            cam_release_devq(ccb->ccb_h.path, 0, 0, 0, 0);

      if (error == 0) {
            if (loc.flags & SA_RPOS_UNCERTAIN) {
                  error = EINVAL;         /* nothing is certain */
            } else {
                  *blkptr = scsi_4btoul(loc.firstblk);
            }
      }

      xpt_release_ccb(ccb);
      return (error);
}

static int
sasetpos(struct cam_periph *periph, int hard, u_int32_t *blkptr)
{
      union ccb *ccb;
      struct sa_softc *softc;
      int error;

      /*
       * We used to try and flush any buffered writes here.
       * Now we push this onto user applications to either
       * flush the pending writes themselves (via a zero count
       * WRITE FILEMARKS command) or they can trust their tape
       * drive to do this correctly for them.
       */

      softc = (struct sa_softc *)periph->softc;
      ccb = cam_periph_getccb(periph, 1);

      
      scsi_set_position(&ccb->csio, 1, sadone, MSG_SIMPLE_Q_TAG,
          hard, *blkptr, SSD_FULL_SIZE, SPACE_TIMEOUT);


      softc->dsreg = MTIO_DSREG_POS;
      error = cam_periph_runccb(ccb, saerror, 0, 0, softc->device_stats);
      softc->dsreg = MTIO_DSREG_REST;
      if ((ccb->ccb_h.status & CAM_DEV_QFRZN) != 0)
            cam_release_devq(ccb->ccb_h.path, 0, 0, 0, 0);
      xpt_release_ccb(ccb);
      /*
       * Note relative file && block number position as now unknown.
       */
      softc->fileno = softc->blkno = (daddr_t) -1;
      return (error);
}

static int
saretension(struct cam_periph *periph)
{
      union ccb *ccb;
      struct sa_softc *softc;
      int error;

      softc = (struct sa_softc *)periph->softc;

      ccb = cam_periph_getccb(periph, 1);

      /* It is safe to retry this operation */
      scsi_load_unload(&ccb->csio, 5, sadone, MSG_SIMPLE_Q_TAG, FALSE,
          FALSE, TRUE,  TRUE, SSD_FULL_SIZE, ERASE_TIMEOUT);

      softc->dsreg = MTIO_DSREG_TEN;
      error = cam_periph_runccb(ccb, saerror, 0, 0, softc->device_stats);
      softc->dsreg = MTIO_DSREG_REST;

      if ((ccb->ccb_h.status & CAM_DEV_QFRZN) != 0)
            cam_release_devq(ccb->ccb_h.path, 0, 0, 0, FALSE);
      xpt_release_ccb(ccb);
      if (error == 0)
            softc->fileno = softc->blkno = (daddr_t) 0;
      else
            softc->fileno = softc->blkno = (daddr_t) -1;
      return (error);
}

static int
sareservereleaseunit(struct cam_periph *periph, int reserve)
{
      union ccb *ccb;
      struct sa_softc *softc;
      int error;

      softc = (struct sa_softc *)periph->softc;
      ccb = cam_periph_getccb(periph,  1);

      /* It is safe to retry this operation */
      scsi_reserve_release_unit(&ccb->csio, 2, sadone, MSG_SIMPLE_Q_TAG,
          FALSE,  0, SSD_FULL_SIZE,  SCSIOP_TIMEOUT, reserve);
      softc->dsreg = MTIO_DSREG_RBSY;
      error = cam_periph_runccb(ccb, saerror, 0,
          SF_RETRY_UA | SF_NO_PRINT, softc->device_stats);
      softc->dsreg = MTIO_DSREG_REST;
      QFRLS(ccb);
      xpt_release_ccb(ccb);

      /*
       * If the error was Illegal Request, then the device doesn't support
       * RESERVE/RELEASE. This is not an error.
       */
      if (error == EINVAL) {
            error = 0;
      }

      return (error);
}

static int
saloadunload(struct cam_periph *periph, int load)
{
      union ccb *ccb;
      struct      sa_softc *softc;
      int   error;

      softc = (struct sa_softc *)periph->softc;

      ccb = cam_periph_getccb(periph, 1);

      /* It is safe to retry this operation */
      scsi_load_unload(&ccb->csio, 5, sadone, MSG_SIMPLE_Q_TAG, FALSE,
          FALSE, FALSE, load, SSD_FULL_SIZE, REWIND_TIMEOUT);

      softc->dsreg = (load)? MTIO_DSREG_LD : MTIO_DSREG_UNL;
      error = cam_periph_runccb(ccb, saerror, 0, 0, softc->device_stats);
      softc->dsreg = MTIO_DSREG_REST;
      QFRLS(ccb);
      xpt_release_ccb(ccb);

      if (error || load == 0)
            softc->fileno = softc->blkno = (daddr_t) -1;
      else if (error == 0)
            softc->fileno = softc->blkno = (daddr_t) 0;
      return (error);
}

static int
saerase(struct cam_periph *periph, int longerase)
{

      union ccb *ccb;
      struct      sa_softc *softc;
      int error;

      softc = (struct sa_softc *)periph->softc;
      if (softc->open_rdonly)
            return (EBADF);

      ccb = cam_periph_getccb(periph, 1);

      scsi_erase(&ccb->csio, 1, sadone, MSG_SIMPLE_Q_TAG, FALSE, longerase,
          SSD_FULL_SIZE, ERASE_TIMEOUT);

      softc->dsreg = MTIO_DSREG_ZER;
      error = cam_periph_runccb(ccb, saerror, 0, 0, softc->device_stats);
      softc->dsreg = MTIO_DSREG_REST;

      if ((ccb->ccb_h.status & CAM_DEV_QFRZN) != 0)
            cam_release_devq(ccb->ccb_h.path, 0, 0, 0, FALSE);
      xpt_release_ccb(ccb);
      return (error);
}

#endif /* _KERNEL */

/*
 * Read tape block limits command.
 */
void
scsi_read_block_limits(struct ccb_scsiio *csio, u_int32_t retries,
               void (*cbfcnp)(struct cam_periph *, union ccb *),
               u_int8_t tag_action,
               struct scsi_read_block_limits_data *rlimit_buf,
               u_int8_t sense_len, u_int32_t timeout)
{
      struct scsi_read_block_limits *scsi_cmd;

      cam_fill_csio(csio, retries, cbfcnp, CAM_DIR_IN, tag_action,
           (u_int8_t *)rlimit_buf, sizeof(*rlimit_buf), sense_len,
           sizeof(*scsi_cmd), timeout);

      scsi_cmd = (struct scsi_read_block_limits *)&csio->cdb_io.cdb_bytes;
      bzero(scsi_cmd, sizeof(*scsi_cmd));
      scsi_cmd->opcode = READ_BLOCK_LIMITS;
}

void
scsi_sa_read_write(struct ccb_scsiio *csio, u_int32_t retries,
               void (*cbfcnp)(struct cam_periph *, union ccb *),
               u_int8_t tag_action, int readop, int sli,
               int fixed, u_int32_t length, u_int8_t *data_ptr,
               u_int32_t dxfer_len, u_int8_t sense_len, u_int32_t timeout)
{
      struct scsi_sa_rw *scsi_cmd;

      scsi_cmd = (struct scsi_sa_rw *)&csio->cdb_io.cdb_bytes;
      scsi_cmd->opcode = readop ? SA_READ : SA_WRITE;
      scsi_cmd->sli_fixed = 0;
      if (sli && readop)
            scsi_cmd->sli_fixed |= SAR_SLI;
      if (fixed)
            scsi_cmd->sli_fixed |= SARW_FIXED;
      scsi_ulto3b(length, scsi_cmd->length);
      scsi_cmd->control = 0;

      cam_fill_csio(csio, retries, cbfcnp, readop ? CAM_DIR_IN : CAM_DIR_OUT,
          tag_action, data_ptr, dxfer_len, sense_len,
          sizeof(*scsi_cmd), timeout);
}

void
scsi_load_unload(struct ccb_scsiio *csio, u_int32_t retries,         
             void (*cbfcnp)(struct cam_periph *, union ccb *),   
             u_int8_t tag_action, int immediate, int eot,
             int reten, int load, u_int8_t sense_len,
             u_int32_t timeout)
{
      struct scsi_load_unload *scsi_cmd;

      scsi_cmd = (struct scsi_load_unload *)&csio->cdb_io.cdb_bytes;
      bzero(scsi_cmd, sizeof(*scsi_cmd));
      scsi_cmd->opcode = LOAD_UNLOAD;
      if (immediate)
            scsi_cmd->immediate = SLU_IMMED;
      if (eot)
            scsi_cmd->eot_reten_load |= SLU_EOT;
      if (reten)
            scsi_cmd->eot_reten_load |= SLU_RETEN;
      if (load)
            scsi_cmd->eot_reten_load |= SLU_LOAD;

      cam_fill_csio(csio, retries, cbfcnp, CAM_DIR_NONE, tag_action,
          NULL, 0, sense_len, sizeof(*scsi_cmd), timeout);  
}

void
scsi_rewind(struct ccb_scsiio *csio, u_int32_t retries,         
          void (*cbfcnp)(struct cam_periph *, union ccb *),   
          u_int8_t tag_action, int immediate, u_int8_t sense_len,     
          u_int32_t timeout)
{
      struct scsi_rewind *scsi_cmd;

      scsi_cmd = (struct scsi_rewind *)&csio->cdb_io.cdb_bytes;
      bzero(scsi_cmd, sizeof(*scsi_cmd));
      scsi_cmd->opcode = REWIND;
      if (immediate)
            scsi_cmd->immediate = SREW_IMMED;
      
      cam_fill_csio(csio, retries, cbfcnp, CAM_DIR_NONE, tag_action, NULL,
          0, sense_len, sizeof(*scsi_cmd), timeout);
}

void
scsi_space(struct ccb_scsiio *csio, u_int32_t retries,
         void (*cbfcnp)(struct cam_periph *, union ccb *),
         u_int8_t tag_action, scsi_space_code code,
         u_int32_t count, u_int8_t sense_len, u_int32_t timeout)
{
      struct scsi_space *scsi_cmd;

      scsi_cmd = (struct scsi_space *)&csio->cdb_io.cdb_bytes;
      scsi_cmd->opcode = SPACE;
      scsi_cmd->code = code;
      scsi_ulto3b(count, scsi_cmd->count);
      scsi_cmd->control = 0;

      cam_fill_csio(csio, retries, cbfcnp, CAM_DIR_NONE, tag_action, NULL,
          0, sense_len, sizeof(*scsi_cmd), timeout);
}

void
scsi_write_filemarks(struct ccb_scsiio *csio, u_int32_t retries,
                 void (*cbfcnp)(struct cam_periph *, union ccb *),
                 u_int8_t tag_action, int immediate, int setmark,
                 u_int32_t num_marks, u_int8_t sense_len,
                 u_int32_t timeout)
{
      struct scsi_write_filemarks *scsi_cmd;

      scsi_cmd = (struct scsi_write_filemarks *)&csio->cdb_io.cdb_bytes;
      bzero(scsi_cmd, sizeof(*scsi_cmd));
      scsi_cmd->opcode = WRITE_FILEMARKS;
      if (immediate)
            scsi_cmd->byte2 |= SWFMRK_IMMED;
      if (setmark)
            scsi_cmd->byte2 |= SWFMRK_WSMK;
      
      scsi_ulto3b(num_marks, scsi_cmd->num_marks);

      cam_fill_csio(csio, retries, cbfcnp, CAM_DIR_NONE, tag_action, NULL,
          0, sense_len, sizeof(*scsi_cmd), timeout);
}

/*
 * The reserve and release unit commands differ only by their opcodes.
 */
void
scsi_reserve_release_unit(struct ccb_scsiio *csio, u_int32_t retries,
                    void (*cbfcnp)(struct cam_periph *, union ccb *),
                    u_int8_t tag_action, int third_party,
                    int third_party_id, u_int8_t sense_len,
                    u_int32_t timeout, int reserve)
{
      struct scsi_reserve_release_unit *scsi_cmd;

      scsi_cmd = (struct scsi_reserve_release_unit *)&csio->cdb_io.cdb_bytes;
      bzero(scsi_cmd, sizeof(*scsi_cmd));

      if (reserve)
            scsi_cmd->opcode = RESERVE_UNIT;
      else
            scsi_cmd->opcode = RELEASE_UNIT;

      if (third_party) {
            scsi_cmd->lun_thirdparty |= SRRU_3RD_PARTY;
            scsi_cmd->lun_thirdparty |=
                  ((third_party_id << SRRU_3RD_SHAMT) & SRRU_3RD_MASK);
      }

      cam_fill_csio(csio, retries, cbfcnp, CAM_DIR_NONE, tag_action, NULL,
          0, sense_len, sizeof(*scsi_cmd), timeout);
}

void
scsi_erase(struct ccb_scsiio *csio, u_int32_t retries,
         void (*cbfcnp)(struct cam_periph *, union ccb *),
         u_int8_t tag_action, int immediate, int long_erase,
         u_int8_t sense_len, u_int32_t timeout)
{
      struct scsi_erase *scsi_cmd;

      scsi_cmd = (struct scsi_erase *)&csio->cdb_io.cdb_bytes;
      bzero(scsi_cmd, sizeof(*scsi_cmd));

      scsi_cmd->opcode = ERASE;

      if (immediate)
            scsi_cmd->lun_imm_long |= SE_IMMED;

      if (long_erase)
            scsi_cmd->lun_imm_long |= SE_LONG;

      cam_fill_csio(csio, retries, cbfcnp, CAM_DIR_NONE, tag_action, NULL,
          0, sense_len, sizeof(*scsi_cmd), timeout);
}

/*
 * Read Tape Position command.
 */
void
scsi_read_position(struct ccb_scsiio *csio, u_int32_t retries,
               void (*cbfcnp)(struct cam_periph *, union ccb *),
               u_int8_t tag_action, int hardsoft,
               struct scsi_tape_position_data *sbp,
               u_int8_t sense_len, u_int32_t timeout)
{
      struct scsi_tape_read_position *scmd;

      cam_fill_csio(csio, retries, cbfcnp, CAM_DIR_IN, tag_action,
          (u_int8_t *)sbp, sizeof (*sbp), sense_len, sizeof(*scmd), timeout);
      scmd = (struct scsi_tape_read_position *)&csio->cdb_io.cdb_bytes;
      bzero(scmd, sizeof(*scmd));
      scmd->opcode = READ_POSITION;
      scmd->byte1 = hardsoft;
}

/*
 * Set Tape Position command.
 */
void
scsi_set_position(struct ccb_scsiio *csio, u_int32_t retries,
               void (*cbfcnp)(struct cam_periph *, union ccb *),
               u_int8_t tag_action, int hardsoft, u_int32_t blkno,
               u_int8_t sense_len, u_int32_t timeout)
{
      struct scsi_tape_locate *scmd;

      cam_fill_csio(csio, retries, cbfcnp, CAM_DIR_NONE, tag_action,
          (u_int8_t *)NULL, 0, sense_len, sizeof(*scmd), timeout);
      scmd = (struct scsi_tape_locate *)&csio->cdb_io.cdb_bytes;
      bzero(scmd, sizeof(*scmd));
      scmd->opcode = LOCATE;
      if (hardsoft)
            scmd->byte1 |= SA_SPOS_BT;
      scsi_ulto4b(blkno, scmd->blkaddr);
}

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