/*
 * 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 $
 */
/*
 * 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/conf.h>
#include <sys/caps.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_POLLED,
        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_bio         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[CHET_MAX + 1];        /* firsts */
        int             sc_counts[CHET_MAX + 1];        /* counts */

        /*
         * The following mask defines the legal combinations
         * of elements for the MOVE MEDIUM command.
         */
        u_int8_t        sc_movemask[CHET_MAX + 1];

        /*
         * As above, but for EXCHANGE MEDIUM.
         */
        u_int8_t        sc_exchangemask[CHET_MAX + 1];

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

#define CHUNIT(x)       (minor((x)))

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
};

PERIPHDRIVER_DECLARE(ch, chdriver);

static struct dev_ops ch_ops = {
        { "ch", 0, 0 },
        .d_open = chopen,
        .d_close = chclose,
        .d_ioctl = chioctl
};

static struct extend_array *chperiphs;

MALLOC_DEFINE(M_SCSICH, "scsi_ch", "scsi_ch buffers");

static void
chinit(void)
{
        cam_status status;

        /*
         * Create our extend array for storing the devices we attach to.
         */
        chperiphs = cam_extend_new();
        if (chperiphs == NULL) {
                kprintf("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_register_async(AC_FOUND_DEVICE, chasync, NULL, NULL);

        if (status != CAM_REQ_CMP) {
                kprintf("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;

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

        /*
         * De-register any async callbacks.
         */
        xpt_register_async(0, chasync, periph, periph->path);

        softc->flags |= CH_FLAG_INVALID;

        xpt_print(periph->path, "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(periph->path, "removing device entry\n");
        dev_ops_remove_minor(&ch_ops, periph->unit_number);
        kfree(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 (cgd == NULL)
                        break;

                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)
                        kprintf("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_getdev *cgd;

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

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

        softc = kmalloc(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.
         */
        cam_periph_unlock(periph);
        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 */
        make_dev(&ch_ops, periph->unit_number, UID_ROOT,
                  GID_OPERATOR, 0600, "%s%d", periph->periph_name,
                  periph->unit_number);
        cam_periph_lock(periph);

        /*
         * Add an async callback so that we get
         * notified if this device goes away.
         */
        xpt_register_async(AC_LOST_DEVICE, chasync, periph, periph->path);

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

        return(CAM_REQ_CMP);
}

static int
chopen(struct dev_open_args *ap)
{
        cdev_t dev = ap->a_head.a_dev;
        struct cam_periph *periph;
        struct ch_softc *softc;
        int unit, error;

        /*
         * Disallow CAM access if RESTRICTEDROOT
         */
        if (caps_priv_check_self(SYSCAP_RESTRICTEDROOT))
                return (EPERM);

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

        if (cam_periph_acquire(periph) != CAM_REQ_CMP)
                return (ENXIO);

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

        cam_periph_lock(periph);

        if (softc->flags & CH_FLAG_INVALID) {
                cam_periph_unlock(periph);
                cam_periph_release(periph);
                return(ENXIO);
        }

        if ((softc->flags & CH_FLAG_OPEN) == 0)
                softc->flags |= CH_FLAG_OPEN;
        else
                cam_periph_release(periph);

        if ((error = cam_periph_hold(periph, PCATCH)) != 0) {
                cam_periph_unlock(periph);
                cam_periph_release(periph);
                return (error);
        }

        /*
         * Load information about this changer device into the softc.
         */
        if ((error = chgetparams(periph)) != 0) {
                softc->flags &= ~CH_FLAG_OPEN;
                cam_periph_unhold(periph, 1);
                cam_periph_release(periph);
        } else {
                cam_periph_unhold(periph, 1);
        }

        return(error);
}

static int
chclose(struct dev_close_args *ap)
{
        cdev_t dev = ap->a_head.a_dev;
        struct  cam_periph *periph;
        struct  ch_softc *softc;
        int     unit;

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

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

        cam_periph_lock(periph);

        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;

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

        switch (softc->state) {
        case CH_STATE_NORMAL:
        {
                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;
                        wakeup(&periph->ccb_list);
                }
                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 = kmalloc(mode_buffer_len, M_SCSICH, 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_bio = 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_POLLED:
                /* Caller releases ccb */
                wakeup(&done_ccb->ccb_h.cbfcnp);
                return;
        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"
                        ksnprintf(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, CAM_RETRY_SELTO,
                                        SF_RETRY_UA | SF_NO_PRINT);
                        /*
                         * 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(periph->path,
                                            "got CAM status %#x\n",
                                            done_ccb->ccb_h.status);
                                }
                                xpt_print(periph->path, "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;
                kfree(mode_header, M_SCSICH);
                /*
                 * 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_unhold(periph, 0);
                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(struct dev_ioctl_args *ap)
{
        cdev_t dev = ap->a_head.a_dev;
        caddr_t addr = ap->a_data;
        int flag = ap->a_fflag;
        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_periph_lock(periph);
        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", ap->a_cmd));

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

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

        switch (ap->a_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)) {
                        error = EINVAL;
                        break;
                }
                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, ap->a_cmd, addr, cherror);
                break;
        }

        cam_periph_unlock(periph);
        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);
        ccb->ccb_h.ccb_state = CH_CCB_POLLED;

        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*/CAM_RETRY_SELTO,
                                  /*sense_flags*/ SF_RETRY_UA,
                                  &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);
        ccb->ccb_h.ccb_state = CH_CCB_POLLED;

        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*/CAM_RETRY_SELTO,
                                  /*sense_flags*/ SF_RETRY_UA,
                                  &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);
        ccb->ccb_h.ccb_state = CH_CCB_POLLED;

        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*/ CAM_RETRY_SELTO,
                                  /*sense_flags*/ SF_RETRY_UA,
                                  &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))
                        kprintf("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.
         */
        cam_periph_unlock(periph);
        data = (caddr_t)kmalloc(1024, M_DEVBUF, M_INTWAIT);

        cam_periph_lock(periph);
        ccb = cam_periph_getccb(periph, /*priority*/ 1);
        ccb->ccb_h.ccb_state = CH_CCB_POLLED;

        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*/ CAM_RETRY_SELTO,
                                  /*sense_flags*/ SF_RETRY_UA,
                                  &softc->device_stats);

        if (error)
                goto done;
        cam_periph_unlock(periph);

        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.
         */
        kfree(data, M_DEVBUF);
        data = (caddr_t)kmalloc(size, M_DEVBUF, M_INTWAIT);

        cam_periph_lock(periph);
        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*/ CAM_RETRY_SELTO,
                                  /*sense_flags*/ SF_RETRY_UA,
                                  &softc->device_stats);

        if (error)
                goto done;
        cam_periph_unlock(periph);

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

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

        user_data = (struct changer_element_status *)
                kmalloc(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));
        cam_periph_lock(periph);

 done:
        xpt_release_ccb(ccb);

        if (data != NULL)
                kfree(data, M_DEVBUF);
        if (user_data != NULL)
                kfree(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);
        ccb->ccb_h.ccb_state = CH_CCB_POLLED;

        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*/ CAM_RETRY_SELTO,
                                  /*sense_flags*/ SF_RETRY_UA,
                                  &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);
        ccb->ccb_h.ccb_state = CH_CCB_POLLED;

        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*/ CAM_RETRY_SELTO,
                                  /*sense_flags*/ SF_RETRY_UA,
                                  &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);
        ccb->ccb_h.ccb_state = CH_CCB_POLLED;

        /*
         * 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 = kmalloc(mode_buffer_len, M_SCSICH, 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*/ CAM_RETRY_SELTO,
                                  /* sense_flags */ SF_RETRY_UA|SF_NO_PRINT,
                                  &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*/ CAM_RETRY_SELTO,
                                                  /*sense_flags*/ SF_RETRY_UA,
                                                  &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(periph->path,
                            "chgetparams: error getting element "
                            "address page\n");
                        xpt_release_ccb(ccb);
                        kfree(mode_buffer, M_SCSICH);
                        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*/ CAM_RETRY_SELTO,
                                  /* sense_flags */ SF_RETRY_UA | SF_NO_PRINT,
                                  &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*/ CAM_RETRY_SELTO,
                                                  /*sense_flags*/ SF_RETRY_UA,
                                                  &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(periph->path,
                            "chgetparams: error getting device "
                            "capabilities page\n");
                        xpt_release_ccb(ccb);
                        kfree(mode_buffer, M_SCSICH);
                        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;
        exchanges = cap->exchange_with;
        for (from = CHET_MT; from <= CHET_MAX; ++from) {
                softc->sc_movemask[from] = moves[from];
                softc->sc_exchangemask[from] = exchanges[from];
        }

        kfree(mode_buffer, M_SCSICH);

        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);
}