File:  [DragonFly] / src / sys / bus / cam / scsi / scsi_ch.c
Revision 1.10: download - view: text, annotated - select for diffs
Wed May 19 22:52:38 2004 UTC (10 years, 6 months ago) by dillon
Branches: MAIN
CVS tags: HEAD, DragonFly_Stable, DragonFly_Snap29Sep2004, DragonFly_Snap13Sep2004, DragonFly_RELEASE_1_2_Slip, DragonFly_RELEASE_1_2, DragonFly_1_0_REL, DragonFly_1_0_RC1, DragonFly_1_0A_REL
Device layer rollup commit.

* cdevsw_add() is now required.  cdevsw_add() and cdevsw_remove() may specify
  a mask/match indicating the range of supported minor numbers.  Multiple
  cdevsw_add()'s using the same major number, but distinctly different
  ranges, may be issued.  All devices that failed to call cdevsw_add() before
  now do.

* cdevsw_remove() now automatically marks all devices within its supported
  range as being destroyed.

* vnode->v_rdev is no longer resolved when the vnode is created.  Instead,
  only v_udev (a newly added field) is resolved.  v_rdev is resolved when
  the vnode is opened and cleared on the last close.

* A great deal of code was making rather dubious assumptions with regards
  to the validity of devices associated with vnodes, primarily due to
  the persistence of a device structure due to being indexed by (major, minor)
  instead of by (cdevsw, major, minor).  In particular, if you run a program
  which connects to a USB device and then you pull the USB device and plug
  it back in, the vnode subsystem will continue to believe that the device
  is open when, in fact, it isn't (because it was destroyed and recreated).

  In particular, note that all the VFS mount procedures now check devices
  via v_udev instead of v_rdev prior to calling VOP_OPEN(), since v_rdev
  is NULL prior to the first open.

* The disk layer's device interaction has been rewritten.  The disk layer
  (i.e. the slice and disklabel management layer) no longer overloads
  its data onto the device structure representing the underlying physical
  disk.  Instead, the disk layer uses the new cdevsw_add() functionality
  to register its own cdevsw using the underlying device's major number,
  and simply does NOT register the underlying device's cdevsw.  No
  confusion is created because the device hash is now based on
  (cdevsw,major,minor) rather then (major,minor).

  NOTE: This also means that underlying raw disk devices may use the entire
  device minor number instead of having to reserve the bits used by the disk
  layer, and also means that can we (theoretically) stack a fully
  disklabel-supported 'disk' on top of any block device.

* The new reference counting scheme prevents this by associating a device
  with a cdevsw and disconnecting the device from its cdevsw when the cdevsw
  is removed.  Additionally, all udev2dev() lookups run through the cdevsw
  mask/match and only successfully find devices still associated with an
  active cdevsw.

* Major work on MFS:  MFS no longer shortcuts vnode and device creation.  It
  now creates a real vnode and a real device and implements real open and
  close VOPs.  Additionally, due to the disk layer changes, MFS is no longer
  limited to 255 mounts.  The new limit is 16 million.  Since MFS creates a
  real device node, mount_mfs will now create a real /dev/mfs<PID> device
  that can be read from userland (e.g. so you can dump an MFS filesystem).

* BUF AND DEVICE STRATEGY changes.  The struct buf contains a b_dev field.
  In order to properly handle stacked devices we now require that the b_dev
  field be initialized before the device strategy routine is called.  This
  required some additional work in various VFS implementations.  To enforce
  this requirement, biodone() now sets b_dev to NODEV.  The new disk layer
  will adjust b_dev before forwarding a request to the actual physical
  device.

* A bug in the ISO CD boot sequence which resulted in a panic has been fixed.

Testing by: lots of people, but David Rhodus found the most aggregious bugs.

/*
 * Copyright (c) 1997 Justin T. Gibbs.
 * Copyright (c) 1997, 1998, 1999 Kenneth D. Merry.
 * 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.
 *
 * $FreeBSD: src/sys/cam/scsi/scsi_ch.c,v 1.20.2.2 2000/10/31 08:09:49 dwmalone Exp $
 * $DragonFly: src/sys/bus/cam/scsi/scsi_ch.c,v 1.10 2004/05/19 22:52:38 dillon Exp $
 */
/*
 * Derived from the NetBSD SCSI changer driver.
 *
 *	$NetBSD: ch.c,v 1.32 1998/01/12 09:49:12 thorpej Exp $
 *
 */
/*
 * Copyright (c) 1996, 1997 Jason R. Thorpe <thorpej@and.com>
 * All rights reserved.
 *
 * Partially based on an autochanger driver written by Stefan Grefen
 * and on an autochanger driver written by the Systems Programming Group
 * at the University of Utah Computer Science Department.
 *
 * 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.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgements:
 *	This product includes software developed by Jason R. Thorpe
 *	for And Communications, http://www.and.com/
 * 4. 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 ``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 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/param.h>
#include <sys/queue.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/types.h>
#include <sys/malloc.h>
#include <sys/fcntl.h>
#include <sys/stat.h>
#include <sys/conf.h>
#include <sys/buf.h>
#include <sys/chio.h>
#include <sys/errno.h>
#include <sys/devicestat.h>

#include "../cam.h"
#include "../cam_ccb.h"
#include "../cam_extend.h"
#include "../cam_periph.h"
#include "../cam_xpt_periph.h"
#include "../cam_queue.h"
#include "../cam_debug.h"

#include "scsi_all.h"
#include "scsi_message.h"
#include "scsi_ch.h"

/*
 * Timeout definitions for various changer related commands.  They may
 * be too short for some devices (especially the timeout for INITIALIZE
 * ELEMENT STATUS).
 */

static const u_int32_t	CH_TIMEOUT_MODE_SENSE                = 6000;
static const u_int32_t	CH_TIMEOUT_MOVE_MEDIUM               = 100000;
static const u_int32_t	CH_TIMEOUT_EXCHANGE_MEDIUM           = 100000;
static const u_int32_t	CH_TIMEOUT_POSITION_TO_ELEMENT       = 100000;
static const u_int32_t	CH_TIMEOUT_READ_ELEMENT_STATUS       = 10000;
static const u_int32_t	CH_TIMEOUT_SEND_VOLTAG		     = 10000;
static const u_int32_t	CH_TIMEOUT_INITIALIZE_ELEMENT_STATUS = 500000;

typedef enum {
	CH_FLAG_INVALID		= 0x001,
	CH_FLAG_OPEN		= 0x002
} ch_flags;

typedef enum {
	CH_STATE_PROBE,
	CH_STATE_NORMAL
} ch_state;

typedef enum {
	CH_CCB_PROBE,
	CH_CCB_WAITING
} ch_ccb_types;

typedef enum {
	CH_Q_NONE	= 0x00,
	CH_Q_NO_DBD	= 0x01
} ch_quirks;

#define ccb_state	ppriv_field0
#define ccb_bp		ppriv_ptr1

struct scsi_mode_sense_data {
	struct scsi_mode_header_6 header;
	struct scsi_mode_blk_desc blk_desc;
	union {
		struct page_element_address_assignment ea;
		struct page_transport_geometry_parameters tg;
		struct page_device_capabilities cap;
	} pages;
};

struct ch_softc {
	ch_flags	flags;
	ch_state	state;
	ch_quirks	quirks;
	union ccb	saved_ccb;
	struct devstat	device_stats;

	int		sc_picker;	/* current picker */

	/*
	 * The following information is obtained from the
	 * element address assignment page.
	 */
	int		sc_firsts[4];	/* firsts, indexed by CHET_* */
	int		sc_counts[4];	/* counts, indexed by CHET_* */

	/*
	 * The following mask defines the legal combinations
	 * of elements for the MOVE MEDIUM command.
	 */
	u_int8_t	sc_movemask[4];

	/*
	 * As above, but for EXCHANGE MEDIUM.
	 */
	u_int8_t	sc_exchangemask[4];

	/*
	 * Quirks; see below.  XXX KDM not implemented yet
	 */
	int		sc_settledelay;	/* delay for settle */
};

#define CHUNIT(x)       (minor((x)))
#define CH_CDEV_MAJOR	17

static	d_open_t	chopen;
static	d_close_t	chclose;
static	d_ioctl_t	chioctl;
static	periph_init_t	chinit;
static  periph_ctor_t	chregister;
static	periph_oninv_t	choninvalidate;
static  periph_dtor_t   chcleanup;
static  periph_start_t  chstart;
static	void		chasync(void *callback_arg, u_int32_t code,
				struct cam_path *path, void *arg);
static	void		chdone(struct cam_periph *periph,
			       union ccb *done_ccb);
static	int		cherror(union ccb *ccb, u_int32_t cam_flags,
				u_int32_t sense_flags);
static	int		chmove(struct cam_periph *periph,
			       struct changer_move *cm);
static	int		chexchange(struct cam_periph *periph,
				   struct changer_exchange *ce);
static	int		chposition(struct cam_periph *periph,
				   struct changer_position *cp);
static	int		chgetelemstatus(struct cam_periph *periph,
				struct changer_element_status_request *csr);
static	int		chsetvoltag(struct cam_periph *periph,
				    struct changer_set_voltag_request *csvr);
static	int		chielem(struct cam_periph *periph, 
				unsigned int timeout);
static	int		chgetparams(struct cam_periph *periph);

static struct periph_driver chdriver =
{
	chinit, "ch",
	TAILQ_HEAD_INITIALIZER(chdriver.units), /* generation */ 0
};

DATA_SET(periphdriver_set, chdriver);

static struct cdevsw ch_cdevsw = {
	/* name */	"ch",
	/* maj */	CH_CDEV_MAJOR,
	/* flags */	0,
	/* port */	NULL,
	/* clone */     NULL,

	/* open */	chopen,
	/* close */	chclose,
	/* read */	noread,
	/* write */	nowrite,
	/* ioctl */	chioctl,
	/* poll */	nopoll,
	/* mmap */	nommap,
	/* strategy */	nostrategy,
	/* dump */	nodump,
	/* psize */	nopsize
};

static struct extend_array *chperiphs;

void
chinit(void)
{
	cam_status status;
	struct cam_path *path;

	/*
	 * Create our extend array for storing the devices we attach to.
	 */
	chperiphs = cam_extend_new();
	if (chperiphs == NULL) {
		printf("ch: Failed to alloc extend array!\n");
		return;
	}

	/*
	 * Install a global async callback.  This callback will
	 * receive async callbacks like "new device found".
	 */
	status = xpt_create_path(&path, /*periph*/NULL, CAM_XPT_PATH_ID,
				 CAM_TARGET_WILDCARD, CAM_LUN_WILDCARD);

	if (status == CAM_REQ_CMP) {
		struct ccb_setasync csa;

                xpt_setup_ccb(&csa.ccb_h, path, /*priority*/5);
                csa.ccb_h.func_code = XPT_SASYNC_CB;
                csa.event_enable = AC_FOUND_DEVICE;
                csa.callback = chasync;
                csa.callback_arg = NULL;
                xpt_action((union ccb *)&csa);
		status = csa.ccb_h.status;
                xpt_free_path(path);
        }

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

static void
choninvalidate(struct cam_periph *periph)
{
	struct ch_softc *softc;
	struct ccb_setasync csa;

	softc = (struct ch_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 = chasync;
	csa.callback_arg = periph;
	xpt_action((union ccb *)&csa);

	softc->flags |= CH_FLAG_INVALID;

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

}

static void
chcleanup(struct cam_periph *periph)
{
	struct ch_softc *softc;

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

	devstat_remove_entry(&softc->device_stats);
	cam_extend_release(chperiphs, periph->unit_number);
	xpt_print_path(periph->path);
	printf("removing device entry\n");
	cdevsw_remove(&ch_cdevsw, -1, periph->unit_number);
	free(softc, M_DEVBUF);
}

static void
chasync(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 (SID_TYPE(&cgd->inq_data)!= T_CHANGER)
			break;

		/*
		 * Allocate a peripheral instance for
		 * this device and start the probe
		 * process.
		 */
		status = cam_periph_alloc(chregister, choninvalidate,
					  chcleanup, chstart, "ch",
					  CAM_PERIPH_BIO, cgd->ccb_h.path,
					  chasync, AC_FOUND_DEVICE, cgd);

		if (status != CAM_REQ_CMP
		 && status != CAM_REQ_INPROG)
			printf("chasync: 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
chregister(struct cam_periph *periph, void *arg)
{
	struct ch_softc *softc;
	struct ccb_setasync csa;
	struct ccb_getdev *cgd;

	cgd = (struct ccb_getdev *)arg;
	if (periph == NULL) {
		printf("chregister: periph was NULL!!\n");
		return(CAM_REQ_CMP_ERR);
	}

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

	softc = malloc(sizeof(*softc), M_DEVBUF, M_INTWAIT | M_ZERO);
	softc->state = CH_STATE_PROBE;
	periph->softc = softc;
	cam_extend_set(chperiphs, periph->unit_number, periph);
	softc->quirks = CH_Q_NONE;

	/*
	 * Changers don't have a blocksize, and obviously don't support
	 * tagged queueing.
	 */
	devstat_add_entry(&softc->device_stats, "ch",
			  periph->unit_number, 0,
			  DEVSTAT_NO_BLOCKSIZE | DEVSTAT_NO_ORDERED_TAGS,
			  SID_TYPE(&cgd->inq_data)| DEVSTAT_TYPE_IF_SCSI,
			  DEVSTAT_PRIORITY_OTHER);

	/* Register the device */
	cdevsw_add(&ch_cdevsw, -1, periph->unit_number);
	make_dev(&ch_cdevsw, periph->unit_number, UID_ROOT,
		  GID_OPERATOR, 0600, "%s%d", periph->periph_name,
		  periph->unit_number);

	/*
	 * 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 = chasync;
	csa.callback_arg = periph;
	xpt_action((union ccb *)&csa);

	/*
	 * Lock this peripheral until we are setup.
	 * This first call can't block
	 */
	(void)cam_periph_lock(periph, 0);
	xpt_schedule(periph, /*priority*/5);

	return(CAM_REQ_CMP);
}

static int
chopen(dev_t dev, int flags, int fmt, struct thread *td)
{
	struct cam_periph *periph;
	struct ch_softc *softc;
	int unit, error;
	int s;

	unit = CHUNIT(dev);
	periph = cam_extend_get(chperiphs, unit);

	if (periph == NULL)
		return(ENXIO);

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

	s = splsoftcam();
	if (softc->flags & CH_FLAG_INVALID) {
		splx(s);
		return(ENXIO);
	}

	if ((error = cam_periph_lock(periph, PCATCH)) != 0) {
		splx(s);
		return (error);
	}
	
	splx(s);

	if ((softc->flags & CH_FLAG_OPEN) == 0) {
		if (cam_periph_acquire(periph) != CAM_REQ_CMP)
			return(ENXIO);
		softc->flags |= CH_FLAG_OPEN;
	}

	/*
	 * Load information about this changer device into the softc.
	 */
	if ((error = chgetparams(periph)) != 0) {
		softc->flags &= ~CH_FLAG_OPEN;
		cam_periph_unlock(periph);
		cam_periph_release(periph);
		return(error);
	}

	cam_periph_unlock(periph);

	return(error);
}

static int
chclose(dev_t dev, int flag, int fmt, struct thread *td)
{
	struct	cam_periph *periph;
	struct	ch_softc *softc;
	int	unit, error;

	error = 0;

	unit = CHUNIT(dev);
	periph = cam_extend_get(chperiphs, unit);
	if (periph == NULL)
		return(ENXIO);

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

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

	softc->flags &= ~CH_FLAG_OPEN;

	cam_periph_unlock(periph);
	cam_periph_release(periph);

	return(0);
}

static void
chstart(struct cam_periph *periph, union ccb *start_ccb)
{
	struct ch_softc *softc;
	int s;

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

	switch (softc->state) {
	case CH_STATE_NORMAL:
	{
		s = splbio();
		if (periph->immediate_priority <= periph->pinfo.priority){
			start_ccb->ccb_h.ccb_state = CH_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
			splx(s);
		break;
	}
	case CH_STATE_PROBE:
	{
		int mode_buffer_len;
		void *mode_buffer;

		/*
		 * Include the block descriptor when calculating the mode
		 * buffer length,
		 */
		mode_buffer_len = sizeof(struct scsi_mode_header_6) +
				  sizeof(struct scsi_mode_blk_desc) +
				 sizeof(struct page_element_address_assignment);

		mode_buffer = malloc(mode_buffer_len, M_TEMP, M_INTWAIT | M_ZERO);
		/*
		 * Get the element address assignment page.
		 */
		scsi_mode_sense(&start_ccb->csio,
				/* retries */ 1,
				/* cbfcnp */ chdone,
				/* tag_action */ MSG_SIMPLE_Q_TAG,
				/* dbd */ (softc->quirks & CH_Q_NO_DBD) ?
					FALSE : TRUE,
				/* page_code */ SMS_PAGE_CTRL_CURRENT,
				/* page */ CH_ELEMENT_ADDR_ASSIGN_PAGE,
				/* param_buf */ (u_int8_t *)mode_buffer,
				/* param_len */ mode_buffer_len,
				/* sense_len */ SSD_FULL_SIZE,
				/* timeout */ CH_TIMEOUT_MODE_SENSE);

		start_ccb->ccb_h.ccb_bp = NULL;
		start_ccb->ccb_h.ccb_state = CH_CCB_PROBE;
		xpt_action(start_ccb);
		break;
	}
	}
}

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

	softc = (struct ch_softc *)periph->softc;
	csio = &done_ccb->csio;

	switch(done_ccb->ccb_h.ccb_state) {
	case CH_CCB_PROBE:
	{
		struct scsi_mode_header_6 *mode_header;
		struct page_element_address_assignment *ea;
		char announce_buf[80];


		mode_header = (struct scsi_mode_header_6 *)csio->data_ptr;

		ea = (struct page_element_address_assignment *)
			find_mode_page_6(mode_header);

		if ((done_ccb->ccb_h.status & CAM_STATUS_MASK) == CAM_REQ_CMP){
			
			softc->sc_firsts[CHET_MT] = scsi_2btoul(ea->mtea);
			softc->sc_counts[CHET_MT] = scsi_2btoul(ea->nmte);
			softc->sc_firsts[CHET_ST] = scsi_2btoul(ea->fsea);
			softc->sc_counts[CHET_ST] = scsi_2btoul(ea->nse);
			softc->sc_firsts[CHET_IE] = scsi_2btoul(ea->fieea);
			softc->sc_counts[CHET_IE] = scsi_2btoul(ea->niee);
			softc->sc_firsts[CHET_DT] = scsi_2btoul(ea->fdtea);
			softc->sc_counts[CHET_DT] = scsi_2btoul(ea->ndte);
			softc->sc_picker = softc->sc_firsts[CHET_MT];

#define PLURAL(c)	(c) == 1 ? "" : "s"
			snprintf(announce_buf, sizeof(announce_buf),
				"%d slot%s, %d drive%s, "
				"%d picker%s, %d portal%s",
		    		softc->sc_counts[CHET_ST],
				PLURAL(softc->sc_counts[CHET_ST]),
		    		softc->sc_counts[CHET_DT],
				PLURAL(softc->sc_counts[CHET_DT]),
		    		softc->sc_counts[CHET_MT],
				PLURAL(softc->sc_counts[CHET_MT]),
		    		softc->sc_counts[CHET_IE],
				PLURAL(softc->sc_counts[CHET_IE]));
#undef PLURAL
		} else {
			int error;

			error = cherror(done_ccb, 0, SF_RETRY_UA |
					SF_NO_PRINT | SF_RETRY_SELTO);
			/*
			 * Retry any UNIT ATTENTION type errors.  They
			 * are expected at boot.
			 */
			if (error == ERESTART) {
				/*
				 * A retry was scheuled, so
				 * just return.
				 */
				return;
			} else if (error != 0) {
				int retry_scheduled;
				struct scsi_mode_sense_6 *sms;

				sms = (struct scsi_mode_sense_6 *)
					done_ccb->csio.cdb_io.cdb_bytes;

				/*
				 * Check to see if block descriptors were
				 * disabled.  Some devices don't like that.
				 * We're taking advantage of the fact that
				 * the first few bytes of the 6 and 10 byte
				 * mode sense commands are the same.  If
				 * block descriptors were disabled, enable
				 * them and re-send the command.
				 */
				if (sms->byte2 & SMS_DBD) {
					sms->byte2 &= ~SMS_DBD;
					xpt_action(done_ccb);
					softc->quirks |= CH_Q_NO_DBD;
					retry_scheduled = 1;
				} else
					retry_scheduled = 0;

				/* Don't wedge this device's queue */
				cam_release_devq(done_ccb->ccb_h.path,
						 /*relsim_flags*/0,
						 /*reduction*/0,
						 /*timeout*/0,
						 /*getcount_only*/0);

				if (retry_scheduled)
					return;

				if ((done_ccb->ccb_h.status & CAM_STATUS_MASK)
				    == CAM_SCSI_STATUS_ERROR) 
					scsi_sense_print(&done_ccb->csio);
				else {
					xpt_print_path(periph->path);
					printf("got CAM status %#x\n",
					       done_ccb->ccb_h.status);
				}
				xpt_print_path(periph->path);
				printf("fatal error, failed to attach to"
				       " device\n");

				cam_periph_invalidate(periph);

				announce_buf[0] = '\0';
			}
		}
		if (announce_buf[0] != '\0')
			xpt_announce_periph(periph, announce_buf);
		softc->state = CH_STATE_NORMAL;
		free(mode_header, M_TEMP);
		/*
		 * Since our peripheral may be invalidated by an error
		 * above or an external event, we must release our CCB
		 * before releasing the probe lock on the peripheral.
		 * The peripheral will only go away once the last lock
		 * is removed, and we need it around for the CCB release
		 * operation.
		 */
		xpt_release_ccb(done_ccb);
		cam_periph_unlock(periph);
		return;
	}
	case CH_CCB_WAITING:
	{
		/* Caller will release the CCB */
		wakeup(&done_ccb->ccb_h.cbfcnp);
		return;
	}
	default:
		break;
	}
	xpt_release_ccb(done_ccb);
}

static int
cherror(union ccb *ccb, u_int32_t cam_flags, u_int32_t sense_flags)
{
	struct ch_softc *softc;
	struct cam_periph *periph;

	periph = xpt_path_periph(ccb->ccb_h.path);
	softc = (struct ch_softc *)periph->softc;

	return (cam_periph_error(ccb, cam_flags, sense_flags,
				 &softc->saved_ccb));
}

static int
chioctl(dev_t dev, u_long cmd, caddr_t addr, int flag, struct thread *td)
{
	struct cam_periph *periph;
	struct ch_softc *softc;
	u_int8_t unit;
	int error;

	unit = CHUNIT(dev);

	periph = cam_extend_get(chperiphs, unit);
	if (periph == NULL)
		return(ENXIO);

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

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

	error = 0;

	CAM_DEBUG(periph->path, CAM_DEBUG_TRACE, 
		  ("trying to do ioctl %#lx\n", cmd));

	/*
	 * If this command can change the device's state, we must
	 * have the device open for writing.
	 */
	switch (cmd) {
	case CHIOGPICKER:
	case CHIOGPARAMS:
	case CHIOGSTATUS:
		break;

	default:
		if ((flag & FWRITE) == 0)
			return (EBADF);
	}

	switch (cmd) {
	case CHIOMOVE:
		error = chmove(periph, (struct changer_move *)addr);
		break;

	case CHIOEXCHANGE:
		error = chexchange(periph, (struct changer_exchange *)addr);
		break;

	case CHIOPOSITION:
		error = chposition(periph, (struct changer_position *)addr);
		break;

	case CHIOGPICKER:
		*(int *)addr = softc->sc_picker - softc->sc_firsts[CHET_MT];
		break;

	case CHIOSPICKER:
	{
		int new_picker = *(int *)addr;

		if (new_picker > (softc->sc_counts[CHET_MT] - 1))
			return (EINVAL);
		softc->sc_picker = softc->sc_firsts[CHET_MT] + new_picker;
		break;
	}
	case CHIOGPARAMS:
	{
		struct changer_params *cp = (struct changer_params *)addr;

		cp->cp_npickers = softc->sc_counts[CHET_MT];
		cp->cp_nslots = softc->sc_counts[CHET_ST];
		cp->cp_nportals = softc->sc_counts[CHET_IE];
		cp->cp_ndrives = softc->sc_counts[CHET_DT];
		break;
	}
	case CHIOIELEM:
		error = chielem(periph, *(unsigned int *)addr);
		break;

	case CHIOGSTATUS:
	{
		error = chgetelemstatus(periph,
			       (struct changer_element_status_request *) addr);
		break;
	}

	case CHIOSETVOLTAG:
	{
		error = chsetvoltag(periph,
				    (struct changer_set_voltag_request *) addr);
		break;
	}

	/* Implement prevent/allow? */

	default:
		error = cam_periph_ioctl(periph, cmd, addr, cherror);
		break;
	}

	return (error);
}

static int
chmove(struct cam_periph *periph, struct changer_move *cm)
{
	struct ch_softc *softc;
	u_int16_t fromelem, toelem;
	union ccb *ccb;
	int error;

	error = 0;
	softc = (struct ch_softc *)periph->softc;

	/*
	 * Check arguments.
	 */
	if ((cm->cm_fromtype > CHET_DT) || (cm->cm_totype > CHET_DT))
		return (EINVAL);
	if ((cm->cm_fromunit > (softc->sc_counts[cm->cm_fromtype] - 1)) ||
	    (cm->cm_tounit > (softc->sc_counts[cm->cm_totype] - 1)))
		return (ENODEV);

	/*
	 * Check the request against the changer's capabilities.
	 */
	if ((softc->sc_movemask[cm->cm_fromtype] & (1 << cm->cm_totype)) == 0)
		return (ENODEV);

	/*
	 * Calculate the source and destination elements.
	 */
	fromelem = softc->sc_firsts[cm->cm_fromtype] + cm->cm_fromunit;
	toelem = softc->sc_firsts[cm->cm_totype] + cm->cm_tounit;

	ccb = cam_periph_getccb(periph, /*priority*/ 1);

	scsi_move_medium(&ccb->csio,
			 /* retries */ 1,
			 /* cbfcnp */ chdone,
			 /* tag_action */ MSG_SIMPLE_Q_TAG,
			 /* tea */ softc->sc_picker,
			 /* src */ fromelem,
			 /* dst */ toelem,
			 /* invert */ (cm->cm_flags & CM_INVERT) ? TRUE : FALSE,
			 /* sense_len */ SSD_FULL_SIZE,
			 /* timeout */ CH_TIMEOUT_MOVE_MEDIUM);

	error = cam_periph_runccb(ccb, cherror, /*cam_flags*/0,
				  /*sense_flags*/ SF_RETRY_UA | SF_RETRY_SELTO,
				  &softc->device_stats);

	xpt_release_ccb(ccb);

	return(error);
}

static int
chexchange(struct cam_periph *periph, struct changer_exchange *ce)
{
	struct ch_softc *softc;
	u_int16_t src, dst1, dst2;
	union ccb *ccb;
	int error;

	error = 0;
	softc = (struct ch_softc *)periph->softc;
	/*
	 * Check arguments.
	 */
	if ((ce->ce_srctype > CHET_DT) || (ce->ce_fdsttype > CHET_DT) ||
	    (ce->ce_sdsttype > CHET_DT))
		return (EINVAL);
	if ((ce->ce_srcunit > (softc->sc_counts[ce->ce_srctype] - 1)) ||
	    (ce->ce_fdstunit > (softc->sc_counts[ce->ce_fdsttype] - 1)) ||
	    (ce->ce_sdstunit > (softc->sc_counts[ce->ce_sdsttype] - 1)))
		return (ENODEV);

	/*
	 * Check the request against the changer's capabilities.
	 */
	if (((softc->sc_exchangemask[ce->ce_srctype] &
	     (1 << ce->ce_fdsttype)) == 0) ||
	    ((softc->sc_exchangemask[ce->ce_fdsttype] &
	     (1 << ce->ce_sdsttype)) == 0))
		return (ENODEV);

	/*
	 * Calculate the source and destination elements.
	 */
	src = softc->sc_firsts[ce->ce_srctype] + ce->ce_srcunit;
	dst1 = softc->sc_firsts[ce->ce_fdsttype] + ce->ce_fdstunit;
	dst2 = softc->sc_firsts[ce->ce_sdsttype] + ce->ce_sdstunit;

	ccb = cam_periph_getccb(periph, /*priority*/ 1);

	scsi_exchange_medium(&ccb->csio,
			     /* retries */ 1,
			     /* cbfcnp */ chdone,
			     /* tag_action */ MSG_SIMPLE_Q_TAG,
			     /* tea */ softc->sc_picker,
			     /* src */ src,
			     /* dst1 */ dst1,
			     /* dst2 */ dst2,
			     /* invert1 */ (ce->ce_flags & CE_INVERT1) ?
			                   TRUE : FALSE,
			     /* invert2 */ (ce->ce_flags & CE_INVERT2) ?
			                   TRUE : FALSE,
			     /* sense_len */ SSD_FULL_SIZE,
			     /* timeout */ CH_TIMEOUT_EXCHANGE_MEDIUM);

	error = cam_periph_runccb(ccb, cherror, /*cam_flags*/0,
				  /*sense_flags*/ SF_RETRY_UA | SF_RETRY_SELTO,
				  &softc->device_stats);

	xpt_release_ccb(ccb);

	return(error);
}

static int
chposition(struct cam_periph *periph, struct changer_position *cp)
{
	struct ch_softc *softc;
	u_int16_t dst;
	union ccb *ccb;
	int error;

	error = 0;
	softc = (struct ch_softc *)periph->softc;

	/*
	 * Check arguments.
	 */
	if (cp->cp_type > CHET_DT)
		return (EINVAL);
	if (cp->cp_unit > (softc->sc_counts[cp->cp_type] - 1))
		return (ENODEV);

	/*
	 * Calculate the destination element.
	 */
	dst = softc->sc_firsts[cp->cp_type] + cp->cp_unit;

	ccb = cam_periph_getccb(periph, /*priority*/ 1);

	scsi_position_to_element(&ccb->csio,
				 /* retries */ 1,
				 /* cbfcnp */ chdone,
				 /* tag_action */ MSG_SIMPLE_Q_TAG,
				 /* tea */ softc->sc_picker,
				 /* dst */ dst,
				 /* invert */ (cp->cp_flags & CP_INVERT) ?
					      TRUE : FALSE,
				 /* sense_len */ SSD_FULL_SIZE,
				 /* timeout */ CH_TIMEOUT_POSITION_TO_ELEMENT);

	error = cam_periph_runccb(ccb, cherror, /*cam_flags*/ 0,
				  /*sense_flags*/ SF_RETRY_UA | SF_RETRY_SELTO,
				  &softc->device_stats);

	xpt_release_ccb(ccb);

	return(error);
}

/*
 * Copy a volume tag to a volume_tag struct, converting SCSI byte order
 * to host native byte order in the volume serial number.  The volume
 * label as returned by the changer is transferred to user mode as
 * nul-terminated string.  Volume labels are truncated at the first
 * space, as suggested by SCSI-2.
 */
static	void
copy_voltag(struct changer_voltag *uvoltag, struct volume_tag *voltag)
{
	int i;
	for (i=0; i<CH_VOLTAG_MAXLEN; i++) {
		char c = voltag->vif[i];
		if (c && c != ' ')
			uvoltag->cv_volid[i] = c;
	        else
			break;
	}
	uvoltag->cv_serial = scsi_2btoul(voltag->vsn);
}

/*
 * Copy an an element status descriptor to a user-mode
 * changer_element_status structure.
 */

static	void
copy_element_status(struct ch_softc *softc,
		    u_int16_t flags,
		    struct read_element_status_descriptor *desc,
		    struct changer_element_status *ces)
{
	u_int16_t eaddr = scsi_2btoul(desc->eaddr);
	u_int16_t et;

	ces->ces_int_addr = eaddr;
	/* set up logical address in element status */
	for (et = CHET_MT; et <= CHET_DT; et++) {
		if ((softc->sc_firsts[et] <= eaddr)
		    && ((softc->sc_firsts[et] + softc->sc_counts[et])
			> eaddr)) {
			ces->ces_addr = eaddr - softc->sc_firsts[et];
			ces->ces_type = et;
			break;
		}
	}

	ces->ces_flags = desc->flags1;

	ces->ces_sensecode = desc->sense_code;
	ces->ces_sensequal = desc->sense_qual;

	if (desc->flags2 & READ_ELEMENT_STATUS_INVERT)
		ces->ces_flags |= CES_INVERT;

	if (desc->flags2 & READ_ELEMENT_STATUS_SVALID) {

		eaddr = scsi_2btoul(desc->ssea);

		/* convert source address to logical format */
		for (et = CHET_MT; et <= CHET_DT; et++) {
			if ((softc->sc_firsts[et] <= eaddr)
			    && ((softc->sc_firsts[et] + softc->sc_counts[et])
				> eaddr)) {
				ces->ces_source_addr = 
					eaddr - softc->sc_firsts[et];
				ces->ces_source_type = et;
				ces->ces_flags |= CES_SOURCE_VALID;
				break;
			}
		}

		if (!(ces->ces_flags & CES_SOURCE_VALID))
			printf("ch: warning: could not map element source "
			       "address %ud to a valid element type\n",
			       eaddr);
	}
			

	if (flags & READ_ELEMENT_STATUS_PVOLTAG)
		copy_voltag(&(ces->ces_pvoltag), &(desc->pvoltag));
	if (flags & READ_ELEMENT_STATUS_AVOLTAG)
		copy_voltag(&(ces->ces_avoltag), &(desc->avoltag));

	if (desc->dt_scsi_flags & READ_ELEMENT_STATUS_DT_IDVALID) {
		ces->ces_flags |= CES_SCSIID_VALID;
		ces->ces_scsi_id = desc->dt_scsi_addr;
	}

	if (desc->dt_scsi_addr & READ_ELEMENT_STATUS_DT_LUVALID) {
		ces->ces_flags |= CES_LUN_VALID;
		ces->ces_scsi_lun = 
			desc->dt_scsi_flags & READ_ELEMENT_STATUS_DT_LUNMASK;
	}
}

static int
chgetelemstatus(struct cam_periph *periph, 
		struct changer_element_status_request *cesr)
{
	struct read_element_status_header *st_hdr;
	struct read_element_status_page_header *pg_hdr;
	struct read_element_status_descriptor *desc;
	caddr_t data = NULL;
	size_t size, desclen;
	int avail, i, error = 0;
	struct changer_element_status *user_data = NULL;
	struct ch_softc *softc;
	union ccb *ccb;
	int chet = cesr->cesr_element_type;
	int want_voltags = (cesr->cesr_flags & CESR_VOLTAGS) ? 1 : 0;

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

	/* perform argument checking */

	/*
	 * Perform a range check on the cesr_element_{base,count}
	 * request argument fields.
	 */
	if ((softc->sc_counts[chet] - cesr->cesr_element_base) <= 0
	    || (cesr->cesr_element_base + cesr->cesr_element_count)
	        > softc->sc_counts[chet])
		return (EINVAL);

	/*
	 * Request one descriptor for the given element type.  This
	 * is used to determine the size of the descriptor so that
	 * we can allocate enough storage for all of them.  We assume
	 * that the first one can fit into 1k.
	 */
	data = (caddr_t)malloc(1024, M_DEVBUF, M_INTWAIT);

	ccb = cam_periph_getccb(periph, /*priority*/ 1);

	scsi_read_element_status(&ccb->csio,
				 /* retries */ 1,
				 /* cbfcnp */ chdone,
				 /* tag_action */ MSG_SIMPLE_Q_TAG,
				 /* voltag */ want_voltags,
				 /* sea */ softc->sc_firsts[chet],
				 /* count */ 1,
				 /* data_ptr */ data,
				 /* dxfer_len */ 1024,
				 /* sense_len */ SSD_FULL_SIZE,
				 /* timeout */ CH_TIMEOUT_READ_ELEMENT_STATUS);

	error = cam_periph_runccb(ccb, cherror, /*cam_flags*/ 0,
				  /*sense_flags*/ SF_RETRY_UA | SF_RETRY_SELTO,
				  &softc->device_stats);

	if (error)
		goto done;

	st_hdr = (struct read_element_status_header *)data;
	pg_hdr = (struct read_element_status_page_header *)((uintptr_t)st_hdr +
		  sizeof(struct read_element_status_header));
	desclen = scsi_2btoul(pg_hdr->edl);

	size = sizeof(struct read_element_status_header) +
	       sizeof(struct read_element_status_page_header) +
	       (desclen * cesr->cesr_element_count);

	/*
	 * Reallocate storage for descriptors and get them from the
	 * device.
	 */
	free(data, M_DEVBUF);
	data = (caddr_t)malloc(size, M_DEVBUF, M_INTWAIT);

	scsi_read_element_status(&ccb->csio,
				 /* retries */ 1,
				 /* cbfcnp */ chdone,
				 /* tag_action */ MSG_SIMPLE_Q_TAG,
				 /* voltag */ want_voltags,
				 /* sea */ softc->sc_firsts[chet]
				 + cesr->cesr_element_base,
				 /* count */ cesr->cesr_element_count,
				 /* data_ptr */ data,
				 /* dxfer_len */ size,
				 /* sense_len */ SSD_FULL_SIZE,
				 /* timeout */ CH_TIMEOUT_READ_ELEMENT_STATUS);
	
	error = cam_periph_runccb(ccb, cherror, /*cam_flags*/ 0,
				  /*sense_flags*/ SF_RETRY_UA | SF_RETRY_SELTO,
				  &softc->device_stats);

	if (error)
		goto done;

	/*
	 * Fill in the user status array.
	 */
	st_hdr = (struct read_element_status_header *)data;
	avail = scsi_2btoul(st_hdr->count);

	if (avail != cesr->cesr_element_count) {
		xpt_print_path(periph->path);
		printf("warning, READ ELEMENT STATUS avail != count\n");
	}

	user_data = (struct changer_element_status *)
		malloc(avail * sizeof(struct changer_element_status),
		       M_DEVBUF, M_INTWAIT | M_ZERO);

	desc = (struct read_element_status_descriptor *)((uintptr_t)data +
		sizeof(struct read_element_status_header) +
		sizeof(struct read_element_status_page_header));
	/*
	 * Set up the individual element status structures
	 */
	for (i = 0; i < avail; ++i) {
		struct changer_element_status *ces = &(user_data[i]);

		copy_element_status(softc, pg_hdr->flags, desc, ces);

		desc = (struct read_element_status_descriptor *)
		       ((uintptr_t)desc + desclen);
	}

	/* Copy element status structures out to userspace. */
	error = copyout(user_data,
			cesr->cesr_element_status,
			avail * sizeof(struct changer_element_status));

 done:
	xpt_release_ccb(ccb);

	if (data != NULL)
		free(data, M_DEVBUF);
	if (user_data != NULL)
		free(user_data, M_DEVBUF);

	return (error);
}

static int
chielem(struct cam_periph *periph,
	unsigned int timeout)
{
	union ccb *ccb;
	struct ch_softc *softc;
	int error;

	if (!timeout) {
		timeout = CH_TIMEOUT_INITIALIZE_ELEMENT_STATUS;
	} else {
		timeout *= 1000;
	}

	error = 0;
	softc = (struct ch_softc *)periph->softc;

	ccb = cam_periph_getccb(periph, /*priority*/ 1);

	scsi_initialize_element_status(&ccb->csio,
				      /* retries */ 1,
				      /* cbfcnp */ chdone,
				      /* tag_action */ MSG_SIMPLE_Q_TAG,
				      /* sense_len */ SSD_FULL_SIZE,
				      /* timeout */ timeout);

	error = cam_periph_runccb(ccb, cherror, /*cam_flags*/ 0,
				  /*sense_flags*/ SF_RETRY_UA | SF_RETRY_SELTO,
				  &softc->device_stats);

	xpt_release_ccb(ccb);

	return(error);
}

static int
chsetvoltag(struct cam_periph *periph,
	    struct changer_set_voltag_request *csvr)
{
	union ccb *ccb;
	struct ch_softc *softc;
	u_int16_t ea;
	u_int8_t sac;
	struct scsi_send_volume_tag_parameters ssvtp;
	int error;
	int i;

	error = 0;
	softc = (struct ch_softc *)periph->softc;

	bzero(&ssvtp, sizeof(ssvtp));
	for (i=0; i<sizeof(ssvtp.vitf); i++) {
		ssvtp.vitf[i] = ' ';
	}

	/*
	 * Check arguments.
	 */
	if (csvr->csvr_type > CHET_DT)
		return EINVAL;
	if (csvr->csvr_addr > (softc->sc_counts[csvr->csvr_type] - 1))
		return ENODEV;

	ea = softc->sc_firsts[csvr->csvr_type] + csvr->csvr_addr;

	if (csvr->csvr_flags & CSVR_ALTERNATE) {
		switch (csvr->csvr_flags & CSVR_MODE_MASK) {
		case CSVR_MODE_SET:
			sac = SEND_VOLUME_TAG_ASSERT_ALTERNATE;
			break;
		case CSVR_MODE_REPLACE:
			sac = SEND_VOLUME_TAG_REPLACE_ALTERNATE;
			break;
		case CSVR_MODE_CLEAR:
			sac = SEND_VOLUME_TAG_UNDEFINED_ALTERNATE;
			break;
		default:
			error = EINVAL;
			goto out;
		}
	} else {
		switch (csvr->csvr_flags & CSVR_MODE_MASK) {
		case CSVR_MODE_SET:
			sac = SEND_VOLUME_TAG_ASSERT_PRIMARY;
			break;
		case CSVR_MODE_REPLACE:
			sac = SEND_VOLUME_TAG_REPLACE_PRIMARY;
			break;
		case CSVR_MODE_CLEAR:
			sac = SEND_VOLUME_TAG_UNDEFINED_PRIMARY;
			break;
		default:
			error = EINVAL;
			goto out;
		}
	}

	memcpy(ssvtp.vitf, csvr->csvr_voltag.cv_volid,
	       min(strlen(csvr->csvr_voltag.cv_volid), sizeof(ssvtp.vitf)));
	scsi_ulto2b(csvr->csvr_voltag.cv_serial, ssvtp.minvsn);

	ccb = cam_periph_getccb(periph, /*priority*/ 1);

	scsi_send_volume_tag(&ccb->csio,
			     /* retries */ 1,
			     /* cbfcnp */ chdone,
			     /* tag_action */ MSG_SIMPLE_Q_TAG,
			     /* element_address */ ea,
			     /* send_action_code */ sac,
			     /* parameters */ &ssvtp,
			     /* sense_len */ SSD_FULL_SIZE,
			     /* timeout */ CH_TIMEOUT_SEND_VOLTAG);
	
	error = cam_periph_runccb(ccb, cherror, /*cam_flags*/ 0,
				  /*sense_flags*/ SF_RETRY_UA | SF_RETRY_SELTO,
				  &softc->device_stats);

	xpt_release_ccb(ccb);

 out:
	return error;
}

static int
chgetparams(struct cam_periph *periph)
{
	union ccb *ccb;
	struct ch_softc *softc;
	void *mode_buffer;
	int mode_buffer_len;
	struct page_element_address_assignment *ea;
	struct page_device_capabilities *cap;
	int error, from, dbd;
	u_int8_t *moves, *exchanges;

	error = 0;

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

	ccb = cam_periph_getccb(periph, /*priority*/ 1);

	/*
	 * The scsi_mode_sense_data structure is just a convenience
	 * structure that allows us to easily calculate the worst-case
	 * storage size of the mode sense buffer.
	 */
	mode_buffer_len = sizeof(struct scsi_mode_sense_data);

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

	if (softc->quirks & CH_Q_NO_DBD)
		dbd = FALSE;
	else
		dbd = TRUE;

	/*
	 * Get the element address assignment page.
	 */
	scsi_mode_sense(&ccb->csio,
			/* retries */ 1,
			/* cbfcnp */ chdone,
			/* tag_action */ MSG_SIMPLE_Q_TAG,
			/* dbd */ dbd,
			/* page_code */ SMS_PAGE_CTRL_CURRENT,
			/* page */ CH_ELEMENT_ADDR_ASSIGN_PAGE,
			/* param_buf */ (u_int8_t *)mode_buffer,
			/* param_len */ mode_buffer_len,
			/* sense_len */ SSD_FULL_SIZE,
			/* timeout */ CH_TIMEOUT_MODE_SENSE);

	error = cam_periph_runccb(ccb, cherror, /*cam_flags*/ 0,
				  /* sense_flags */ SF_RETRY_UA |
				  SF_NO_PRINT | SF_RETRY_SELTO,
				  &softc->device_stats);

	if (error) {
		if (dbd) {
			struct scsi_mode_sense_6 *sms;

			sms = (struct scsi_mode_sense_6 *)
				ccb->csio.cdb_io.cdb_bytes;

			sms->byte2 &= ~SMS_DBD;
			error = cam_periph_runccb(ccb, cherror, /*cam_flags*/ 0,
				  		  /*sense_flags*/ SF_RETRY_UA |
						  SF_RETRY_SELTO,
						  &softc->device_stats);
		} else {
			/*
			 * Since we disabled sense printing above, print
			 * out the sense here since we got an error.
			 */
			scsi_sense_print(&ccb->csio);
		}

		if (error) {
			xpt_print_path(periph->path);
			printf("chgetparams: error getting element "
			       "address page\n");
			xpt_release_ccb(ccb);
			free(mode_buffer, M_TEMP);
			return(error);
		}
	}

	ea = (struct page_element_address_assignment *)
		find_mode_page_6((struct scsi_mode_header_6 *)mode_buffer);

	softc->sc_firsts[CHET_MT] = scsi_2btoul(ea->mtea);
	softc->sc_counts[CHET_MT] = scsi_2btoul(ea->nmte);
	softc->sc_firsts[CHET_ST] = scsi_2btoul(ea->fsea);
	softc->sc_counts[CHET_ST] = scsi_2btoul(ea->nse);
	softc->sc_firsts[CHET_IE] = scsi_2btoul(ea->fieea);
	softc->sc_counts[CHET_IE] = scsi_2btoul(ea->niee);
	softc->sc_firsts[CHET_DT] = scsi_2btoul(ea->fdtea);
	softc->sc_counts[CHET_DT] = scsi_2btoul(ea->ndte);

	bzero(mode_buffer, mode_buffer_len);

	/*
	 * Now get the device capabilities page.
	 */
	scsi_mode_sense(&ccb->csio,
			/* retries */ 1,
			/* cbfcnp */ chdone,
			/* tag_action */ MSG_SIMPLE_Q_TAG,
			/* dbd */ dbd,
			/* page_code */ SMS_PAGE_CTRL_CURRENT,
			/* page */ CH_DEVICE_CAP_PAGE,
			/* param_buf */ (u_int8_t *)mode_buffer,
			/* param_len */ mode_buffer_len,
			/* sense_len */ SSD_FULL_SIZE,
			/* timeout */ CH_TIMEOUT_MODE_SENSE);
	
	error = cam_periph_runccb(ccb, cherror, /*cam_flags*/ 0,
				  /* sense_flags */ SF_RETRY_UA | SF_NO_PRINT |
				  SF_RETRY_SELTO, &softc->device_stats);

	if (error) {
		if (dbd) {
			struct scsi_mode_sense_6 *sms;

			sms = (struct scsi_mode_sense_6 *)
				ccb->csio.cdb_io.cdb_bytes;

			sms->byte2 &= ~SMS_DBD;
			error = cam_periph_runccb(ccb, cherror, /*cam_flags*/ 0,
				  		  /*sense_flags*/ SF_RETRY_UA |
						  SF_RETRY_SELTO,
						  &softc->device_stats);
		} else {
			/*
			 * Since we disabled sense printing above, print
			 * out the sense here since we got an error.
			 */
			scsi_sense_print(&ccb->csio);
		}

		if (error) {
			xpt_print_path(periph->path);
			printf("chgetparams: error getting device "
			       "capabilities page\n");
			xpt_release_ccb(ccb);
			free(mode_buffer, M_TEMP);
			return(error);
		}
	}

	xpt_release_ccb(ccb);

	cap = (struct page_device_capabilities *)
		find_mode_page_6((struct scsi_mode_header_6 *)mode_buffer);

	bzero(softc->sc_movemask, sizeof(softc->sc_movemask));
	bzero(softc->sc_exchangemask, sizeof(softc->sc_exchangemask));
	moves = &cap->move_from_mt;
	exchanges = &cap->exchange_with_mt;
	for (from = CHET_MT; from <= CHET_DT; ++from) {
		softc->sc_movemask[from] = moves[from];
		softc->sc_exchangemask[from] = exchanges[from];
	}

	free(mode_buffer, M_TEMP);

	return(error);
}

void
scsi_move_medium(struct ccb_scsiio *csio, u_int32_t retries,
		 void (*cbfcnp)(struct cam_periph *, union ccb *),
		 u_int8_t tag_action, u_int32_t tea, u_int32_t src,
		 u_int32_t dst, int invert, u_int8_t sense_len,
		 u_int32_t timeout)
{
	struct scsi_move_medium *scsi_cmd;

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

	scsi_cmd->opcode = MOVE_MEDIUM;

	scsi_ulto2b(tea, scsi_cmd->tea);
	scsi_ulto2b(src, scsi_cmd->src);
	scsi_ulto2b(dst, scsi_cmd->dst);

	if (invert)
		scsi_cmd->invert |= MOVE_MEDIUM_INVERT;

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

void
scsi_exchange_medium(struct ccb_scsiio *csio, u_int32_t retries,
		     void (*cbfcnp)(struct cam_periph *, union ccb *),
		     u_int8_t tag_action, u_int32_t tea, u_int32_t src,
		     u_int32_t dst1, u_int32_t dst2, int invert1,
		     int invert2, u_int8_t sense_len, u_int32_t timeout)
{
	struct scsi_exchange_medium *scsi_cmd;

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

	scsi_cmd->opcode = EXCHANGE_MEDIUM;

	scsi_ulto2b(tea, scsi_cmd->tea);
	scsi_ulto2b(src, scsi_cmd->src);
	scsi_ulto2b(dst1, scsi_cmd->fdst);
	scsi_ulto2b(dst2, scsi_cmd->sdst);

	if (invert1)
		scsi_cmd->invert |= EXCHANGE_MEDIUM_INV1;

	if (invert2)
		scsi_cmd->invert |= EXCHANGE_MEDIUM_INV2;

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

void
scsi_position_to_element(struct ccb_scsiio *csio, u_int32_t retries,
			 void (*cbfcnp)(struct cam_periph *, union ccb *),
			 u_int8_t tag_action, u_int32_t tea, u_int32_t dst,
			 int invert, u_int8_t sense_len, u_int32_t timeout)
{
	struct scsi_position_to_element *scsi_cmd;

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

	scsi_cmd->opcode = POSITION_TO_ELEMENT;

	scsi_ulto2b(tea, scsi_cmd->tea);
	scsi_ulto2b(dst, scsi_cmd->dst);

	if (invert)
		scsi_cmd->invert |= POSITION_TO_ELEMENT_INVERT;

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

void
scsi_read_element_status(struct ccb_scsiio *csio, u_int32_t retries,
			 void (*cbfcnp)(struct cam_periph *, union ccb *),
			 u_int8_t tag_action, int voltag, u_int32_t sea,
			 u_int32_t count, u_int8_t *data_ptr,
			 u_int32_t dxfer_len, u_int8_t sense_len,
			 u_int32_t timeout)
{
	struct scsi_read_element_status *scsi_cmd;

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

	scsi_cmd->opcode = READ_ELEMENT_STATUS;

	scsi_ulto2b(sea, scsi_cmd->sea);
	scsi_ulto2b(count, scsi_cmd->count);
	scsi_ulto3b(dxfer_len, scsi_cmd->len);

	if (voltag)
		scsi_cmd->byte2 |= READ_ELEMENT_STATUS_VOLTAG;

	cam_fill_csio(csio,
		      retries,
		      cbfcnp,
		      /*flags*/ CAM_DIR_IN,
		      tag_action,
		      data_ptr,
		      dxfer_len,
		      sense_len,
		      sizeof(*scsi_cmd),
		      timeout);
}

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

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

	scsi_cmd->opcode = INITIALIZE_ELEMENT_STATUS;

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

void
scsi_send_volume_tag(struct ccb_scsiio *csio, u_int32_t retries,
		     void (*cbfcnp)(struct cam_periph *, union ccb *),
		     u_int8_t tag_action, 
		     u_int16_t element_address,
		     u_int8_t send_action_code,
		     struct scsi_send_volume_tag_parameters *parameters,
		     u_int8_t sense_len, u_int32_t timeout)
{
	struct scsi_send_volume_tag *scsi_cmd;

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

	scsi_cmd->opcode = SEND_VOLUME_TAG;
	scsi_ulto2b(element_address, scsi_cmd->ea);
	scsi_cmd->sac = send_action_code;
	scsi_ulto2b(sizeof(*parameters), scsi_cmd->pll);

	cam_fill_csio(csio,
		      retries,
		      cbfcnp,
		      /*flags*/ CAM_DIR_OUT,
		      tag_action,
		      /* data_ptr */ (u_int8_t *) parameters,
		      sizeof(*parameters),
		      sense_len,
		      sizeof(*scsi_cmd),
		      timeout);
}