freebsd/sys/cam/cam_periph.c

/*-
 * Common functions for CAM "type" (peripheral) drivers.
 *
 * Copyright (c) 1997, 1998 Justin T. Gibbs.
 * Copyright (c) 1997, 1998, 1999, 2000 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.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/types.h>
#include <sys/malloc.h>
#include <sys/kernel.h>
#include <sys/bio.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/buf.h>
#include <sys/proc.h>
#include <sys/devicestat.h>
#include <sys/bus.h>
#include <sys/sbuf.h>
#include <vm/vm.h>
#include <vm/vm_extern.h>

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

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

static	u_int		camperiphnextunit(struct periph_driver *p_drv,
					  u_int newunit, int wired,
					  path_id_t pathid, target_id_t target,
					  lun_id_t lun);
static	u_int		camperiphunit(struct periph_driver *p_drv,
				      path_id_t pathid, target_id_t target,
				      lun_id_t lun); 
static	void		camperiphdone(struct cam_periph *periph, 
					union ccb *done_ccb);
static  void		camperiphfree(struct cam_periph *periph);
static int		camperiphscsistatuserror(union ccb *ccb,
						 cam_flags camflags,
						 u_int32_t sense_flags,
						 int *openings,
						 u_int32_t *relsim_flags,
						 u_int32_t *timeout,
						 const char **action_string);
static	int		camperiphscsisenseerror(union ccb *ccb,
					        cam_flags camflags,
					        u_int32_t sense_flags,
					        int *openings,
					        u_int32_t *relsim_flags,
					        u_int32_t *timeout,
					        const char **action_string);

static int nperiph_drivers;
static int initialized = 0;
struct periph_driver **periph_drivers;

static MALLOC_DEFINE(M_CAMPERIPH, "CAM periph", "CAM peripheral buffers");

static int periph_selto_delay = 1000;
TUNABLE_INT("kern.cam.periph_selto_delay", &periph_selto_delay);
static int periph_noresrc_delay = 500;
TUNABLE_INT("kern.cam.periph_noresrc_delay", &periph_noresrc_delay);
static int periph_busy_delay = 500;
TUNABLE_INT("kern.cam.periph_busy_delay", &periph_busy_delay);


void
periphdriver_register(void *data)
{
	struct periph_driver *drv = (struct periph_driver *)data;
	struct periph_driver **newdrivers, **old;
	int ndrivers;

	ndrivers = nperiph_drivers + 2;
	newdrivers = malloc(sizeof(*newdrivers) * ndrivers, M_CAMPERIPH,
			    M_WAITOK);
	if (periph_drivers)
		bcopy(periph_drivers, newdrivers,
		      sizeof(*newdrivers) * nperiph_drivers);
	newdrivers[nperiph_drivers] = drv;
	newdrivers[nperiph_drivers + 1] = NULL;
	old = periph_drivers;
	periph_drivers = newdrivers;
	if (old)
		free(old, M_CAMPERIPH);
	nperiph_drivers++;
	/* If driver marked as early or it is late now, initialize it. */
	if (((drv->flags & CAM_PERIPH_DRV_EARLY) != 0 && initialized > 0) ||
	    initialized > 1)
		(*drv->init)();
}

void
periphdriver_init(int level)
{
	int	i, early;

	initialized = max(initialized, level);
	for (i = 0; periph_drivers[i] != NULL; i++) {
		early = (periph_drivers[i]->flags & CAM_PERIPH_DRV_EARLY) ? 1 : 2;
		if (early == initialized)
			(*periph_drivers[i]->init)();
	}
}

cam_status
cam_periph_alloc(periph_ctor_t *periph_ctor,
		 periph_oninv_t *periph_oninvalidate,
		 periph_dtor_t *periph_dtor, periph_start_t *periph_start,
		 char *name, cam_periph_type type, struct cam_path *path,
		 ac_callback_t *ac_callback, ac_code code, void *arg)
{
	struct		periph_driver **p_drv;
	struct		cam_sim *sim;
	struct		cam_periph *periph;
	struct		cam_periph *cur_periph;
	path_id_t	path_id;
	target_id_t	target_id;
	lun_id_t	lun_id;
	cam_status	status;
	u_int		init_level;

	init_level = 0;
	/*
	 * Handle Hot-Plug scenarios.  If there is already a peripheral
	 * of our type assigned to this path, we are likely waiting for
	 * final close on an old, invalidated, peripheral.  If this is
	 * the case, queue up a deferred call to the peripheral's async
	 * handler.  If it looks like a mistaken re-allocation, complain.
	 */
	if ((periph = cam_periph_find(path, name)) != NULL) {

		if ((periph->flags & CAM_PERIPH_INVALID) != 0
		 && (periph->flags & CAM_PERIPH_NEW_DEV_FOUND) == 0) {
			periph->flags |= CAM_PERIPH_NEW_DEV_FOUND;
			periph->deferred_callback = ac_callback;
			periph->deferred_ac = code;
			return (CAM_REQ_INPROG);
		} else {
			printf("cam_periph_alloc: attempt to re-allocate "
			       "valid device %s%d rejected flags %#x "
			       "refcount %d\n", periph->periph_name,
			       periph->unit_number, periph->flags,
			       periph->refcount);
		}
		return (CAM_REQ_INVALID);
	}
	
	periph = (struct cam_periph *)malloc(sizeof(*periph), M_CAMPERIPH,
					     M_NOWAIT|M_ZERO);

	if (periph == NULL)
		return (CAM_RESRC_UNAVAIL);
	
	init_level++;


	sim = xpt_path_sim(path);
	path_id = xpt_path_path_id(path);
	target_id = xpt_path_target_id(path);
	lun_id = xpt_path_lun_id(path);
	cam_init_pinfo(&periph->pinfo);
	periph->periph_start = periph_start;
	periph->periph_dtor = periph_dtor;
	periph->periph_oninval = periph_oninvalidate;
	periph->type = type;
	periph->periph_name = name;
	periph->immediate_priority = CAM_PRIORITY_NONE;
	periph->refcount = 0;
	periph->sim = sim;
	SLIST_INIT(&periph->ccb_list);
	status = xpt_create_path(&path, periph, path_id, target_id, lun_id);
	if (status != CAM_REQ_CMP)
		goto failure;
	periph->path = path;

	xpt_lock_buses();
	for (p_drv = periph_drivers; *p_drv != NULL; p_drv++) {
		if (strcmp((*p_drv)->driver_name, name) == 0)
			break;
	}
	if (*p_drv == NULL) {
		printf("cam_periph_alloc: invalid periph name '%s'\n", name);
		xpt_free_path(periph->path);
		free(periph, M_CAMPERIPH);
		xpt_unlock_buses();
		return (CAM_REQ_INVALID);
	}
	periph->unit_number = camperiphunit(*p_drv, path_id, target_id, lun_id);
	cur_periph = TAILQ_FIRST(&(*p_drv)->units);
	while (cur_periph != NULL
	    && cur_periph->unit_number < periph->unit_number)
		cur_periph = TAILQ_NEXT(cur_periph, unit_links);
	if (cur_periph != NULL) {
		KASSERT(cur_periph->unit_number != periph->unit_number, ("duplicate units on periph list"));
		TAILQ_INSERT_BEFORE(cur_periph, periph, unit_links);
	} else {
		TAILQ_INSERT_TAIL(&(*p_drv)->units, periph, unit_links);
		(*p_drv)->generation++;
	}
	xpt_unlock_buses();

	init_level++;

	status = xpt_add_periph(periph);
	if (status != CAM_REQ_CMP)
		goto failure;

	init_level++;
	CAM_DEBUG(periph->path, CAM_DEBUG_INFO, ("Periph created\n"));

	status = periph_ctor(periph, arg);

	if (status == CAM_REQ_CMP)
		init_level++;

failure:
	switch (init_level) {
	case 4:
		/* Initialized successfully */
		break;
	case 3:
		CAM_DEBUG(periph->path, CAM_DEBUG_INFO, ("Periph destroyed\n"));
		xpt_remove_periph(periph);
		/* FALLTHROUGH */
	case 2:
		xpt_lock_buses();
		TAILQ_REMOVE(&(*p_drv)->units, periph, unit_links);
		xpt_unlock_buses();
		xpt_free_path(periph->path);
		/* FALLTHROUGH */
	case 1:
		free(periph, M_CAMPERIPH);
		/* FALLTHROUGH */
	case 0:
		/* No cleanup to perform. */
		break;
	default:
		panic("cam_periph_alloc: Unkown init level");
	}
	return(status);
}

/*
 * Find a peripheral structure with the specified path, target, lun, 
 * and (optionally) type.  If the name is NULL, this function will return
 * the first peripheral driver that matches the specified path.
 */
struct cam_periph *
cam_periph_find(struct cam_path *path, char *name)
{
	struct periph_driver **p_drv;
	struct cam_periph *periph;

	xpt_lock_buses();
	for (p_drv = periph_drivers; *p_drv != NULL; p_drv++) {

		if (name != NULL && (strcmp((*p_drv)->driver_name, name) != 0))
			continue;

		TAILQ_FOREACH(periph, &(*p_drv)->units, unit_links) {
			if (xpt_path_comp(periph->path, path) == 0) {
				xpt_unlock_buses();
				mtx_assert(periph->sim->mtx, MA_OWNED);
				return(periph);
			}
		}
		if (name != NULL) {
			xpt_unlock_buses();
			return(NULL);
		}
	}
	xpt_unlock_buses();
	return(NULL);
}

/*
 * Find peripheral driver instances attached to the specified path.
 */
int
cam_periph_list(struct cam_path *path, struct sbuf *sb)
{
	struct sbuf local_sb;
	struct periph_driver **p_drv;
	struct cam_periph *periph;
	int count;
	int sbuf_alloc_len;

	sbuf_alloc_len = 16;
retry:
	sbuf_new(&local_sb, NULL, sbuf_alloc_len, SBUF_FIXEDLEN);
	count = 0;
	xpt_lock_buses();
	for (p_drv = periph_drivers; *p_drv != NULL; p_drv++) {

		TAILQ_FOREACH(periph, &(*p_drv)->units, unit_links) {
			if (xpt_path_comp(periph->path, path) != 0)
				continue;

			if (sbuf_len(&local_sb) != 0)
				sbuf_cat(&local_sb, ",");

			sbuf_printf(&local_sb, "%s%d", periph->periph_name,
				    periph->unit_number);

			if (sbuf_error(&local_sb) == ENOMEM) {
				sbuf_alloc_len *= 2;
				xpt_unlock_buses();
				sbuf_delete(&local_sb);
				goto retry;
			}
			count++;
		}
	}
	xpt_unlock_buses();
	sbuf_finish(&local_sb);
	sbuf_cpy(sb, sbuf_data(&local_sb));
	sbuf_delete(&local_sb);
	return (count);
}

cam_status
cam_periph_acquire(struct cam_periph *periph)
{
	cam_status status;

	status = CAM_REQ_CMP_ERR;
	if (periph == NULL)
		return (status);

	xpt_lock_buses();
	if ((periph->flags & CAM_PERIPH_INVALID) == 0) {
		periph->refcount++;
		status = CAM_REQ_CMP;
	}
	xpt_unlock_buses();

	return (status);
}

void
cam_periph_release_locked_buses(struct cam_periph *periph)
{
	if (periph->refcount != 0) {
		periph->refcount--;
	} else {
		panic("%s: release of %p when refcount is zero\n ", __func__,
		      periph);
	}
	if (periph->refcount == 0
	    && (periph->flags & CAM_PERIPH_INVALID)) {
		camperiphfree(periph);
	}
}

void
cam_periph_release_locked(struct cam_periph *periph)
{

	if (periph == NULL)
		return;

	xpt_lock_buses();
	cam_periph_release_locked_buses(periph);
	xpt_unlock_buses();
}

void
cam_periph_release(struct cam_periph *periph)
{
	struct cam_sim *sim;

	if (periph == NULL)
		return;
	
	sim = periph->sim;
	mtx_assert(sim->mtx, MA_NOTOWNED);
	mtx_lock(sim->mtx);
	cam_periph_release_locked(periph);
	mtx_unlock(sim->mtx);
}

int
cam_periph_hold(struct cam_periph *periph, int priority)
{
	int error;

	/*
	 * Increment the reference count on the peripheral
	 * while we wait for our lock attempt to succeed
	 * to ensure the peripheral doesn't disappear out
	 * from user us while we sleep.
	 */

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

	mtx_assert(periph->sim->mtx, MA_OWNED);
	while ((periph->flags & CAM_PERIPH_LOCKED) != 0) {
		periph->flags |= CAM_PERIPH_LOCK_WANTED;
		if ((error = mtx_sleep(periph, periph->sim->mtx, priority,
		    "caplck", 0)) != 0) {
			cam_periph_release_locked(periph);
			return (error);
		}
	}

	periph->flags |= CAM_PERIPH_LOCKED;
	return (0);
}

void
cam_periph_unhold(struct cam_periph *periph)
{

	mtx_assert(periph->sim->mtx, MA_OWNED);

	periph->flags &= ~CAM_PERIPH_LOCKED;
	if ((periph->flags & CAM_PERIPH_LOCK_WANTED) != 0) {
		periph->flags &= ~CAM_PERIPH_LOCK_WANTED;
		wakeup(periph);
	}

	cam_periph_release_locked(periph);
}

/*
 * Look for the next unit number that is not currently in use for this
 * peripheral type starting at "newunit".  Also exclude unit numbers that
 * are reserved by for future "hardwiring" unless we already know that this
 * is a potential wired device.  Only assume that the device is "wired" the
 * first time through the loop since after that we'll be looking at unit
 * numbers that did not match a wiring entry.
 */
static u_int
camperiphnextunit(struct periph_driver *p_drv, u_int newunit, int wired,
		  path_id_t pathid, target_id_t target, lun_id_t lun)
{
	struct	cam_periph *periph;
	char	*periph_name;
	int	i, val, dunit, r;
	const char *dname, *strval;

	periph_name = p_drv->driver_name;
	for (;;newunit++) {

		for (periph = TAILQ_FIRST(&p_drv->units);
		     periph != NULL && periph->unit_number != newunit;
		     periph = TAILQ_NEXT(periph, unit_links))
			;

		if (periph != NULL && periph->unit_number == newunit) {
			if (wired != 0) {
				xpt_print(periph->path, "Duplicate Wired "
				    "Device entry!\n");
				xpt_print(periph->path, "Second device (%s "
				    "device at scbus%d target %d lun %d) will "
				    "not be wired\n", periph_name, pathid,
				    target, lun);
				wired = 0;
			}
			continue;
		}
		if (wired)
			break;

		/*
		 * Don't match entries like "da 4" as a wired down
		 * device, but do match entries like "da 4 target 5"
		 * or even "da 4 scbus 1". 
		 */
		i = 0;
		dname = periph_name;
		for (;;) {
			r = resource_find_dev(&i, dname, &dunit, NULL, NULL);
			if (r != 0)
				break;
			/* if no "target" and no specific scbus, skip */
			if (resource_int_value(dname, dunit, "target", &val) &&
			    (resource_string_value(dname, dunit, "at",&strval)||
			     strcmp(strval, "scbus") == 0))
				continue;
			if (newunit == dunit)
				break;
		}
		if (r != 0)
			break;
	}
	return (newunit);
}

static u_int
camperiphunit(struct periph_driver *p_drv, path_id_t pathid,
	      target_id_t target, lun_id_t lun)
{
	u_int	unit;
	int	wired, i, val, dunit;
	const char *dname, *strval;
	char	pathbuf[32], *periph_name;

	periph_name = p_drv->driver_name;
	snprintf(pathbuf, sizeof(pathbuf), "scbus%d", pathid);
	unit = 0;
	i = 0;
	dname = periph_name;
	for (wired = 0; resource_find_dev(&i, dname, &dunit, NULL, NULL) == 0;
	     wired = 0) {
		if (resource_string_value(dname, dunit, "at", &strval) == 0) {
			if (strcmp(strval, pathbuf) != 0)
				continue;
			wired++;
		}
		if (resource_int_value(dname, dunit, "target", &val) == 0) {
			if (val != target)
				continue;
			wired++;
		}
		if (resource_int_value(dname, dunit, "lun", &val) == 0) {
			if (val != lun)
				continue;
			wired++;
		}
		if (wired != 0) {
			unit = dunit;
			break;
		}
	}

	/*
	 * Either start from 0 looking for the next unit or from
	 * the unit number given in the resource config.  This way,
	 * if we have wildcard matches, we don't return the same
	 * unit number twice.
	 */
	unit = camperiphnextunit(p_drv, unit, wired, pathid, target, lun);

	return (unit);
}

void
cam_periph_invalidate(struct cam_periph *periph)
{

	CAM_DEBUG(periph->path, CAM_DEBUG_INFO, ("Periph invalidated\n"));
	/*
	 * We only call this routine the first time a peripheral is
	 * invalidated.
	 */
	if (((periph->flags & CAM_PERIPH_INVALID) == 0)
	 && (periph->periph_oninval != NULL))
		periph->periph_oninval(periph);

	periph->flags |= CAM_PERIPH_INVALID;
	periph->flags &= ~CAM_PERIPH_NEW_DEV_FOUND;

	xpt_lock_buses();
	if (periph->refcount == 0)
		camperiphfree(periph);
	xpt_unlock_buses();
}

static void
camperiphfree(struct cam_periph *periph)
{
	struct periph_driver **p_drv;

	for (p_drv = periph_drivers; *p_drv != NULL; p_drv++) {
		if (strcmp((*p_drv)->driver_name, periph->periph_name) == 0)
			break;
	}
	if (*p_drv == NULL) {
		printf("camperiphfree: attempt to free non-existant periph\n");
		return;
	}

	TAILQ_REMOVE(&(*p_drv)->units, periph, unit_links);
	(*p_drv)->generation++;
	xpt_unlock_buses();

	if (periph->periph_dtor != NULL)
		periph->periph_dtor(periph);
	xpt_remove_periph(periph);
	CAM_DEBUG(periph->path, CAM_DEBUG_INFO, ("Periph destroyed\n"));

	if (periph->flags & CAM_PERIPH_NEW_DEV_FOUND) {
		union ccb ccb;
		void *arg;

		switch (periph->deferred_ac) {
		case AC_FOUND_DEVICE:
			ccb.ccb_h.func_code = XPT_GDEV_TYPE;
			xpt_setup_ccb(&ccb.ccb_h, periph->path, CAM_PRIORITY_NORMAL);
			xpt_action(&ccb);
			arg = &ccb;
			break;
		case AC_PATH_REGISTERED:
			ccb.ccb_h.func_code = XPT_PATH_INQ;
			xpt_setup_ccb(&ccb.ccb_h, periph->path, CAM_PRIORITY_NORMAL);
			xpt_action(&ccb);
			arg = &ccb;
			break;
		default:
			arg = NULL;
			break;
		}
		periph->deferred_callback(NULL, periph->deferred_ac,
					  periph->path, arg);
	}
	xpt_free_path(periph->path);
	free(periph, M_CAMPERIPH);
	xpt_lock_buses();
}

/*
 * Map user virtual pointers into kernel virtual address space, so we can
 * access the memory.  This won't work on physical pointers, for now it's
 * up to the caller to check for that.  (XXX KDM -- should we do that here
 * instead?)  This also only works for up to MAXPHYS memory.  Since we use
 * buffers to map stuff in and out, we're limited to the buffer size.
 */
int
cam_periph_mapmem(union ccb *ccb, struct cam_periph_map_info *mapinfo)
{
	int numbufs, i, j;
	int flags[CAM_PERIPH_MAXMAPS];
	u_int8_t **data_ptrs[CAM_PERIPH_MAXMAPS];
	u_int32_t lengths[CAM_PERIPH_MAXMAPS];
	u_int32_t dirs[CAM_PERIPH_MAXMAPS];
	/* Some controllers may not be able to handle more data. */
	size_t maxmap = DFLTPHYS;

	switch(ccb->ccb_h.func_code) {
	case XPT_DEV_MATCH:
		if (ccb->cdm.match_buf_len == 0) {
			printf("cam_periph_mapmem: invalid match buffer "
			       "length 0\n");
			return(EINVAL);
		}
		if (ccb->cdm.pattern_buf_len > 0) {
			data_ptrs[0] = (u_int8_t **)&ccb->cdm.patterns;
			lengths[0] = ccb->cdm.pattern_buf_len;
			dirs[0] = CAM_DIR_OUT;
			data_ptrs[1] = (u_int8_t **)&ccb->cdm.matches;
			lengths[1] = ccb->cdm.match_buf_len;
			dirs[1] = CAM_DIR_IN;
			numbufs = 2;
		} else {
			data_ptrs[0] = (u_int8_t **)&ccb->cdm.matches;
			lengths[0] = ccb->cdm.match_buf_len;
			dirs[0] = CAM_DIR_IN;
			numbufs = 1;
		}
		/*
		 * This request will not go to the hardware, no reason
		 * to be so strict. vmapbuf() is able to map up to MAXPHYS.
		 */
		maxmap = MAXPHYS;
		break;
	case XPT_SCSI_IO:
	case XPT_CONT_TARGET_IO:
		if ((ccb->ccb_h.flags & CAM_DIR_MASK) == CAM_DIR_NONE)
			return(0);

		data_ptrs[0] = &ccb->csio.data_ptr;
		lengths[0] = ccb->csio.dxfer_len;
		dirs[0] = ccb->ccb_h.flags & CAM_DIR_MASK;
		numbufs = 1;
		break;
	case XPT_ATA_IO:
		if ((ccb->ccb_h.flags & CAM_DIR_MASK) == CAM_DIR_NONE)
			return(0);

		data_ptrs[0] = &ccb->ataio.data_ptr;
		lengths[0] = ccb->ataio.dxfer_len;
		dirs[0] = ccb->ccb_h.flags & CAM_DIR_MASK;
		numbufs = 1;
		break;
	case XPT_SMP_IO:
		data_ptrs[0] = &ccb->smpio.smp_request;
		lengths[0] = ccb->smpio.smp_request_len;
		dirs[0] = CAM_DIR_OUT;
		data_ptrs[1] = &ccb->smpio.smp_response;
		lengths[1] = ccb->smpio.smp_response_len;
		dirs[1] = CAM_DIR_IN;
		numbufs = 2;
		break;
	case XPT_DEV_ADVINFO:
		if (ccb->cdai.bufsiz == 0)
			return (0);

		data_ptrs[0] = (uint8_t **)&ccb->cdai.buf;
		lengths[0] = ccb->cdai.bufsiz;
		dirs[0] = CAM_DIR_IN;
		numbufs = 1;

		/*
		 * This request will not go to the hardware, no reason
		 * to be so strict. vmapbuf() is able to map up to MAXPHYS.
		 */
		maxmap = MAXPHYS;
		break;
	default:
		return(EINVAL);
		break; /* NOTREACHED */
	}

	/*
	 * Check the transfer length and permissions first, so we don't
	 * have to unmap any previously mapped buffers.
	 */
	for (i = 0; i < numbufs; i++) {

		flags[i] = 0;

		/*
		 * The userland data pointer passed in may not be page
		 * aligned.  vmapbuf() truncates the address to a page
		 * boundary, so if the address isn't page aligned, we'll
		 * need enough space for the given transfer length, plus
		 * whatever extra space is necessary to make it to the page
		 * boundary.
		 */
		if ((lengths[i] +
		    (((vm_offset_t)(*data_ptrs[i])) & PAGE_MASK)) > maxmap){
			printf("cam_periph_mapmem: attempt to map %lu bytes, "
			       "which is greater than %lu\n",
			       (long)(lengths[i] +
			       (((vm_offset_t)(*data_ptrs[i])) & PAGE_MASK)),
			       (u_long)maxmap);
			return(E2BIG);
		}

		if (dirs[i] & CAM_DIR_OUT) {
			flags[i] = BIO_WRITE;
		}

		if (dirs[i] & CAM_DIR_IN) {
			flags[i] = BIO_READ;
		}

	}

	/* this keeps the current process from getting swapped */
	/*
	 * XXX KDM should I use P_NOSWAP instead?
	 */
	PHOLD(curproc);

	for (i = 0; i < numbufs; i++) {
		/*
		 * Get the buffer.
		 */
		mapinfo->bp[i] = getpbuf(NULL);

		/* save the buffer's data address */
		mapinfo->bp[i]->b_saveaddr = mapinfo->bp[i]->b_data;

		/* put our pointer in the data slot */
		mapinfo->bp[i]->b_data = *data_ptrs[i];

		/* set the transfer length, we know it's < MAXPHYS */
		mapinfo->bp[i]->b_bufsize = lengths[i];

		/* set the direction */
		mapinfo->bp[i]->b_iocmd = flags[i];

		/*
		 * Map the buffer into kernel memory.
		 *
		 * Note that useracc() alone is not a  sufficient test.
		 * vmapbuf() can still fail due to a smaller file mapped
		 * into a larger area of VM, or if userland races against
		 * vmapbuf() after the useracc() check.
		 */
		if (vmapbuf(mapinfo->bp[i]) < 0) {
			for (j = 0; j < i; ++j) {
				*data_ptrs[j] = mapinfo->bp[j]->b_saveaddr;
				vunmapbuf(mapinfo->bp[j]);
				relpbuf(mapinfo->bp[j], NULL);
			}
			relpbuf(mapinfo->bp[i], NULL);
			PRELE(curproc);
			return(EACCES);
		}

		/* set our pointer to the new mapped area */
		*data_ptrs[i] = mapinfo->bp[i]->b_data;

		mapinfo->num_bufs_used++;
	}

	/*
	 * Now that we've gotten this far, change ownership to the kernel
	 * of the buffers so that we don't run afoul of returning to user
	 * space with locks (on the buffer) held.
	 */
	for (i = 0; i < numbufs; i++) {
		BUF_KERNPROC(mapinfo->bp[i]);
	}


	return(0);
}

/*
 * Unmap memory segments mapped into kernel virtual address space by
 * cam_periph_mapmem().
 */
void
cam_periph_unmapmem(union ccb *ccb, struct cam_periph_map_info *mapinfo)
{
	int numbufs, i;
	u_int8_t **data_ptrs[CAM_PERIPH_MAXMAPS];

	if (mapinfo->num_bufs_used <= 0) {
		/* allow ourselves to be swapped once again */
		PRELE(curproc);
		return;
	}

	switch (ccb->ccb_h.func_code) {
	case XPT_DEV_MATCH:
		numbufs = min(mapinfo->num_bufs_used, 2);

		if (numbufs == 1) {
			data_ptrs[0] = (u_int8_t **)&ccb->cdm.matches;
		} else {
			data_ptrs[0] = (u_int8_t **)&ccb->cdm.patterns;
			data_ptrs[1] = (u_int8_t **)&ccb->cdm.matches;
		}
		break;
	case XPT_SCSI_IO:
	case XPT_CONT_TARGET_IO:
		data_ptrs[0] = &ccb->csio.data_ptr;
		numbufs = min(mapinfo->num_bufs_used, 1);
		break;
	case XPT_ATA_IO:
		data_ptrs[0] = &ccb->ataio.data_ptr;
		numbufs = min(mapinfo->num_bufs_used, 1);
		break;
	case XPT_SMP_IO:
		numbufs = min(mapinfo->num_bufs_used, 2);
		data_ptrs[0] = &ccb->smpio.smp_request;
		data_ptrs[1] = &ccb->smpio.smp_response;
		break;
	case XPT_DEV_ADVINFO:
		numbufs = min(mapinfo->num_bufs_used, 1);
		data_ptrs[0] = (uint8_t **)&ccb->cdai.buf;
		break;
	default:
		/* allow ourselves to be swapped once again */
		PRELE(curproc);
		return;
		break; /* NOTREACHED */ 
	}

	for (i = 0; i < numbufs; i++) {
		/* Set the user's pointer back to the original value */
		*data_ptrs[i] = mapinfo->bp[i]->b_saveaddr;

		/* unmap the buffer */
		vunmapbuf(mapinfo->bp[i]);

		/* release the buffer */
		relpbuf(mapinfo->bp[i], NULL);
	}

	/* allow ourselves to be swapped once again */
	PRELE(curproc);
}

union ccb *
cam_periph_getccb(struct cam_periph *periph, u_int32_t priority)
{
	struct ccb_hdr *ccb_h;

	mtx_assert(periph->sim->mtx, MA_OWNED);
	CAM_DEBUG(periph->path, CAM_DEBUG_TRACE, ("entering cdgetccb\n"));

	while (SLIST_FIRST(&periph->ccb_list) == NULL) {
		if (periph->immediate_priority > priority)
			periph->immediate_priority = priority;
		xpt_schedule(periph, priority);
		if ((SLIST_FIRST(&periph->ccb_list) != NULL)
		 && (SLIST_FIRST(&periph->ccb_list)->pinfo.priority == priority))
			break;
		mtx_assert(periph->sim->mtx, MA_OWNED);
		mtx_sleep(&periph->ccb_list, periph->sim->mtx, PRIBIO, "cgticb",
		    0);
	}

	ccb_h = SLIST_FIRST(&periph->ccb_list);
	SLIST_REMOVE_HEAD(&periph->ccb_list, periph_links.sle);
	return ((union ccb *)ccb_h);
}

void
cam_periph_ccbwait(union ccb *ccb)
{
	struct cam_sim *sim;

	sim = xpt_path_sim(ccb->ccb_h.path);
	if ((ccb->ccb_h.pinfo.index != CAM_UNQUEUED_INDEX)
	 || ((ccb->ccb_h.status & CAM_STATUS_MASK) == CAM_REQ_INPROG))
		mtx_sleep(&ccb->ccb_h.cbfcnp, sim->mtx, PRIBIO, "cbwait", 0);
}

int
cam_periph_ioctl(struct cam_periph *periph, u_long cmd, caddr_t addr,
		 int (*error_routine)(union ccb *ccb, 
				      cam_flags camflags,
				      u_int32_t sense_flags))
{
	union ccb 	     *ccb;
	int 		     error;
	int		     found;

	error = found = 0;

	switch(cmd){
	case CAMGETPASSTHRU:
		ccb = cam_periph_getccb(periph, CAM_PRIORITY_NORMAL);
		xpt_setup_ccb(&ccb->ccb_h,
			      ccb->ccb_h.path,
			      CAM_PRIORITY_NORMAL);
		ccb->ccb_h.func_code = XPT_GDEVLIST;

		/*
		 * Basically, the point of this is that we go through
		 * getting the list of devices, until we find a passthrough
		 * device.  In the current version of the CAM code, the
		 * only way to determine what type of device we're dealing
		 * with is by its name.
		 */
		while (found == 0) {
			ccb->cgdl.index = 0;
			ccb->cgdl.status = CAM_GDEVLIST_MORE_DEVS;
			while (ccb->cgdl.status == CAM_GDEVLIST_MORE_DEVS) {

				/* we want the next device in the list */
				xpt_action(ccb);
				if (strncmp(ccb->cgdl.periph_name, 
				    "pass", 4) == 0){
					found = 1;
					break;
				}
			}
			if ((ccb->cgdl.status == CAM_GDEVLIST_LAST_DEVICE) &&
			    (found == 0)) {
				ccb->cgdl.periph_name[0] = '\0';
				ccb->cgdl.unit_number = 0;
				break;
			}
		}

		/* copy the result back out */	
		bcopy(ccb, addr, sizeof(union ccb));

		/* and release the ccb */
		xpt_release_ccb(ccb);

		break;
	default:
		error = ENOTTY;
		break;
	}
	return(error);
}

int
cam_periph_runccb(union ccb *ccb,
		  int (*error_routine)(union ccb *ccb,
				       cam_flags camflags,
				       u_int32_t sense_flags),
		  cam_flags camflags, u_int32_t sense_flags,
		  struct devstat *ds)
{
	struct cam_sim *sim;
	int error;
 
	error = 0;
	sim = xpt_path_sim(ccb->ccb_h.path);
	mtx_assert(sim->mtx, MA_OWNED);

	/*
	 * If the user has supplied a stats structure, and if we understand
	 * this particular type of ccb, record the transaction start.
	 */
	if ((ds != NULL) && (ccb->ccb_h.func_code == XPT_SCSI_IO ||
	    ccb->ccb_h.func_code == XPT_ATA_IO))
		devstat_start_transaction(ds, NULL);

	xpt_action(ccb);
 
	do {
		cam_periph_ccbwait(ccb);
		if ((ccb->ccb_h.status & CAM_STATUS_MASK) == CAM_REQ_CMP)
			error = 0;
		else if (error_routine != NULL)
			error = (*error_routine)(ccb, camflags, sense_flags);
		else
			error = 0;

	} while (error == ERESTART);
          
	if ((ccb->ccb_h.status & CAM_DEV_QFRZN) != 0) {
		cam_release_devq(ccb->ccb_h.path,
				 /* relsim_flags */0,
				 /* openings */0,
				 /* timeout */0,
				 /* getcount_only */ FALSE);
		ccb->ccb_h.status &= ~CAM_DEV_QFRZN;
	}

	if (ds != NULL) {
		if (ccb->ccb_h.func_code == XPT_SCSI_IO) {
			devstat_end_transaction(ds,
					ccb->csio.dxfer_len,
					ccb->csio.tag_action & 0x3,
					((ccb->ccb_h.flags & CAM_DIR_MASK) ==
					CAM_DIR_NONE) ?  DEVSTAT_NO_DATA : 
					(ccb->ccb_h.flags & CAM_DIR_OUT) ?
					DEVSTAT_WRITE : 
					DEVSTAT_READ, NULL, NULL);
		} else if (ccb->ccb_h.func_code == XPT_ATA_IO) {
			devstat_end_transaction(ds,
					ccb->ataio.dxfer_len,
					ccb->ataio.tag_action & 0x3,
					((ccb->ccb_h.flags & CAM_DIR_MASK) ==
					CAM_DIR_NONE) ?  DEVSTAT_NO_DATA : 
					(ccb->ccb_h.flags & CAM_DIR_OUT) ?
					DEVSTAT_WRITE : 
					DEVSTAT_READ, NULL, NULL);
		}
	}

	return(error);
}

void
cam_freeze_devq(struct cam_path *path)
{

	cam_freeze_devq_arg(path, 0, 0);
}

void
cam_freeze_devq_arg(struct cam_path *path, uint32_t flags, uint32_t arg)
{
	struct ccb_relsim crs;

	xpt_setup_ccb(&crs.ccb_h, path, CAM_PRIORITY_NONE);
	crs.ccb_h.func_code = XPT_FREEZE_QUEUE;
	crs.release_flags = flags;
	crs.openings = arg;
	crs.release_timeout = arg;
	xpt_action((union ccb *)&crs);
}

u_int32_t
cam_release_devq(struct cam_path *path, u_int32_t relsim_flags,
		 u_int32_t openings, u_int32_t arg,
		 int getcount_only)
{
	struct ccb_relsim crs;

	xpt_setup_ccb(&crs.ccb_h, path, CAM_PRIORITY_NORMAL);
	crs.ccb_h.func_code = XPT_REL_SIMQ;
	crs.ccb_h.flags = getcount_only ? CAM_DEV_QFREEZE : 0;
	crs.release_flags = relsim_flags;
	crs.openings = openings;
	crs.release_timeout = arg;
	xpt_action((union ccb *)&crs);
	return (crs.qfrozen_cnt);
}

#define saved_ccb_ptr ppriv_ptr0
#define recovery_depth ppriv_field1
static void
camperiphsensedone(struct cam_periph *periph, union ccb *done_ccb)
{
	union ccb      *saved_ccb = (union ccb *)done_ccb->ccb_h.saved_ccb_ptr;
	cam_status	status;
	int		frozen = 0;
	int		depth = done_ccb->ccb_h.recovery_depth;

	status = done_ccb->ccb_h.status;
	if (status & CAM_DEV_QFRZN) {
		frozen = 1;
		/*
		 * Clear freeze flag now for case of retry,
		 * freeze will be dropped later.
		 */
		done_ccb->ccb_h.status &= ~CAM_DEV_QFRZN;
	}
	status &= CAM_STATUS_MASK;
	switch (status) {
	case CAM_REQ_CMP:
	{
		int error_code, sense_key, asc, ascq;

		scsi_extract_sense_len(&saved_ccb->csio.sense_data,
				       saved_ccb->csio.sense_len -
				       saved_ccb->csio.sense_resid,
				       &error_code, &sense_key, &asc, &ascq,
				       /*show_errors*/ 1);
		/*
		 * If we manually retrieved sense into a CCB and got
		 * something other than "NO SENSE" send the updated CCB
		 * back to the client via xpt_done() to be processed via
		 * the error recovery code again.
		 */
		if ((sense_key != -1)
		 && (sense_key != SSD_KEY_NO_SENSE)) {
			saved_ccb->ccb_h.status |= CAM_AUTOSNS_VALID;
		} else {
			saved_ccb->ccb_h.status &= ~CAM_STATUS_MASK;
			saved_ccb->ccb_h.status |= CAM_AUTOSENSE_FAIL;
		}
		saved_ccb->csio.sense_resid = done_ccb->csio.resid;
		bcopy(saved_ccb, done_ccb, sizeof(union ccb));
		xpt_free_ccb(saved_ccb);
		break;
	}
	default:
		bcopy(saved_ccb, done_ccb, sizeof(union ccb));
		xpt_free_ccb(saved_ccb);
		done_ccb->ccb_h.status &= ~CAM_STATUS_MASK;
		done_ccb->ccb_h.status |= CAM_AUTOSENSE_FAIL;
		break;
	}
	periph->flags &= ~CAM_PERIPH_SENSE_INPROG;
	/*
	 * If it is the end of recovery, drop freeze, taken due to
	 * CAM_DEV_QFREEZE flag, set on recovery request.
	 */
	if (depth == 0) {
		cam_release_devq(done_ccb->ccb_h.path,
			 /*relsim_flags*/0,
			 /*openings*/0,
			 /*timeout*/0,
			 /*getcount_only*/0);
	}
	/*
	 * Copy frozen flag from recovery request if it is set there
	 * for some reason.
	 */
	if (frozen != 0)
		done_ccb->ccb_h.status |= CAM_DEV_QFRZN;
	(*done_ccb->ccb_h.cbfcnp)(periph, done_ccb);
}

static void
camperiphdone(struct cam_periph *periph, union ccb *done_ccb)
{
	union ccb      *saved_ccb, *save_ccb;
	cam_status	status;
	int		frozen = 0;
	struct scsi_start_stop_unit *scsi_cmd;
	u_int32_t	relsim_flags, timeout;

	status = done_ccb->ccb_h.status;
	if (status & CAM_DEV_QFRZN) {
		frozen = 1;
		/*
		 * Clear freeze flag now for case of retry,
		 * freeze will be dropped later.
		 */
		done_ccb->ccb_h.status &= ~CAM_DEV_QFRZN;
	}

	timeout = 0;
	relsim_flags = 0;
	saved_ccb = (union ccb *)done_ccb->ccb_h.saved_ccb_ptr;

	switch (status & CAM_STATUS_MASK) {
	case CAM_REQ_CMP:
	{
		/*
		 * If we have successfully taken a device from the not
		 * ready to ready state, re-scan the device and re-get
		 * the inquiry information.  Many devices (mostly disks)
		 * don't properly report their inquiry information unless
		 * they are spun up.
		 */
		scsi_cmd = (struct scsi_start_stop_unit *)
				&done_ccb->csio.cdb_io.cdb_bytes;

	 	if (scsi_cmd->opcode == START_STOP_UNIT)
			xpt_async(AC_INQ_CHANGED,
				  done_ccb->ccb_h.path, NULL);
		goto final;
	}
	case CAM_SCSI_STATUS_ERROR:
		scsi_cmd = (struct scsi_start_stop_unit *)
				&done_ccb->csio.cdb_io.cdb_bytes;
		if (status & CAM_AUTOSNS_VALID) {
			struct ccb_getdev cgd;
			struct scsi_sense_data *sense;
			int    error_code, sense_key, asc, ascq, sense_len;
			scsi_sense_action err_action;

			sense = &done_ccb->csio.sense_data;
			sense_len = done_ccb->csio.sense_len -
				    done_ccb->csio.sense_resid;
			scsi_extract_sense_len(sense, sense_len, &error_code, 
					       &sense_key, &asc, &ascq,
					       /*show_errors*/ 1);
			/*
			 * Grab the inquiry data for this device.
			 */
			xpt_setup_ccb(&cgd.ccb_h, done_ccb->ccb_h.path,
			    CAM_PRIORITY_NORMAL);
			cgd.ccb_h.func_code = XPT_GDEV_TYPE;
			xpt_action((union ccb *)&cgd);
			err_action = scsi_error_action(&done_ccb->csio,
						       &cgd.inq_data, 0);
			/*
	 		 * If the error is "invalid field in CDB", 
			 * and the load/eject flag is set, turn the 
			 * flag off and try again.  This is just in 
			 * case the drive in question barfs on the 
			 * load eject flag.  The CAM code should set 
			 * the load/eject flag by default for 
			 * removable media.
			 */
			/* XXX KDM 
			 * Should we check to see what the specific
			 * scsi status is??  Or does it not matter
			 * since we already know that there was an
			 * error, and we know what the specific
			 * error code was, and we know what the
			 * opcode is..
			 */
			if ((scsi_cmd->opcode == START_STOP_UNIT) &&
			    ((scsi_cmd->how & SSS_LOEJ) != 0) &&
			     (asc == 0x24) && (ascq == 0x00) &&
			     (done_ccb->ccb_h.retry_count > 0)) {

				scsi_cmd->how &= ~SSS_LOEJ;
				xpt_action(done_ccb);
			} else if ((done_ccb->ccb_h.retry_count > 1)
				&& ((err_action & SS_MASK) != SS_FAIL)) {

				/*
				 * In this case, the error recovery
				 * command failed, but we've got 
				 * some retries left on it.  Give
				 * it another try unless this is an
				 * unretryable error.
				 */
				/* set the timeout to .5 sec */
				relsim_flags =
					RELSIM_RELEASE_AFTER_TIMEOUT;
				timeout = 500;
				xpt_action(done_ccb);
				break;
			} else {
				/* 
				 * Perform the final retry with the original
				 * CCB so that final error processing is
				 * performed by the owner of the CCB.
				 */
				goto final;
			}
		} else {
			save_ccb = xpt_alloc_ccb_nowait();
			if (save_ccb == NULL)
				goto final;
			bcopy(done_ccb, save_ccb, sizeof(*save_ccb));
			periph->flags |= CAM_PERIPH_SENSE_INPROG;
			/*
			 * Send a Request Sense to the device.  We
			 * assume that we are in a contingent allegiance
			 * condition so we do not tag this request.
			 */
			scsi_request_sense(&done_ccb->csio, /*retries*/1,
					   camperiphsensedone,
					   &save_ccb->csio.sense_data,
					   save_ccb->csio.sense_len,
					   CAM_TAG_ACTION_NONE,
					   /*sense_len*/SSD_FULL_SIZE,
					   /*timeout*/5000);
			done_ccb->ccb_h.pinfo.priority--;
			done_ccb->ccb_h.flags |= CAM_DEV_QFREEZE;
			done_ccb->ccb_h.saved_ccb_ptr = save_ccb;
			done_ccb->ccb_h.recovery_depth++;
			xpt_action(done_ccb);
		}
		break;
	default:
final:
		bcopy(saved_ccb, done_ccb, sizeof(*done_ccb));
		xpt_free_ccb(saved_ccb);
		periph->flags &= ~CAM_PERIPH_RECOVERY_INPROG;
		xpt_action(done_ccb);
		break;
	}

	/* decrement the retry count */
	/*
	 * XXX This isn't appropriate in all cases.  Restructure,
	 *     so that the retry count is only decremented on an
	 *     actual retry.  Remeber that the orignal ccb had its
	 *     retry count dropped before entering recovery, so
	 *     doing it again is a bug.
	 */
	if (done_ccb->ccb_h.retry_count > 0)
		done_ccb->ccb_h.retry_count--;
	/*
	 * Drop freeze taken due to CAM_DEV_QFREEZE flag set on recovery
	 * request.
	 */
	cam_release_devq(done_ccb->ccb_h.path,
			 /*relsim_flags*/relsim_flags,
			 /*openings*/0,
			 /*timeout*/timeout,
			 /*getcount_only*/0);
	/* Drop freeze taken, if this recovery request got error. */
	if (frozen != 0) {
		cam_release_devq(done_ccb->ccb_h.path,
			 /*relsim_flags*/0,
			 /*openings*/0,
			 /*timeout*/0,
			 /*getcount_only*/0);
	}
}

/*
 * Generic Async Event handler.  Peripheral drivers usually
 * filter out the events that require personal attention,
 * and leave the rest to this function.
 */
void
cam_periph_async(struct cam_periph *periph, u_int32_t code,
		 struct cam_path *path, void *arg)
{
	switch (code) {
	case AC_LOST_DEVICE:
		cam_periph_invalidate(periph);
		break; 
	default:
		break;
	}
}

void
cam_periph_bus_settle(struct cam_periph *periph, u_int bus_settle)
{
	struct ccb_getdevstats cgds;

	xpt_setup_ccb(&cgds.ccb_h, periph->path, CAM_PRIORITY_NORMAL);
	cgds.ccb_h.func_code = XPT_GDEV_STATS;
	xpt_action((union ccb *)&cgds);
	cam_periph_freeze_after_event(periph, &cgds.last_reset, bus_settle);
}

void
cam_periph_freeze_after_event(struct cam_periph *periph,
			      struct timeval* event_time, u_int duration_ms)
{
	struct timeval delta;
	struct timeval duration_tv;

	microtime(&delta);
	timevalsub(&delta, event_time);
	duration_tv.tv_sec = duration_ms / 1000;
	duration_tv.tv_usec = (duration_ms % 1000) * 1000;
	if (timevalcmp(&delta, &duration_tv, <)) {
		timevalsub(&duration_tv, &delta);

		duration_ms = duration_tv.tv_sec * 1000;
		duration_ms += duration_tv.tv_usec / 1000;
		cam_freeze_devq(periph->path); 
		cam_release_devq(periph->path,
				RELSIM_RELEASE_AFTER_TIMEOUT,
				/*reduction*/0,
				/*timeout*/duration_ms,
				/*getcount_only*/0);
	}

}

static int
camperiphscsistatuserror(union ccb *ccb, cam_flags camflags,
			 u_int32_t sense_flags,
			 int *openings, u_int32_t *relsim_flags,
			 u_int32_t *timeout, const char **action_string)
{
	int error;

	switch (ccb->csio.scsi_status) {
	case SCSI_STATUS_OK:
	case SCSI_STATUS_COND_MET:
	case SCSI_STATUS_INTERMED:
	case SCSI_STATUS_INTERMED_COND_MET:
		error = 0;
		break;
	case SCSI_STATUS_CMD_TERMINATED:
	case SCSI_STATUS_CHECK_COND:
		if (bootverbose)
			xpt_print(ccb->ccb_h.path, "SCSI status error\n");
		error = camperiphscsisenseerror(ccb,
					        camflags,
					        sense_flags,
					        openings,
					        relsim_flags,
					        timeout,
					        action_string);
		break;
	case SCSI_STATUS_QUEUE_FULL:
	{
		/* no decrement */
		struct ccb_getdevstats cgds;

		/*
		 * First off, find out what the current
		 * transaction counts are.
		 */
		xpt_setup_ccb(&cgds.ccb_h,
			      ccb->ccb_h.path,
			      CAM_PRIORITY_NORMAL);
		cgds.ccb_h.func_code = XPT_GDEV_STATS;
		xpt_action((union ccb *)&cgds);

		/*
		 * If we were the only transaction active, treat
		 * the QUEUE FULL as if it were a BUSY condition.
		 */
		if (cgds.dev_active != 0) {
			int total_openings;

			/*
		 	 * Reduce the number of openings to
			 * be 1 less than the amount it took
			 * to get a queue full bounded by the
			 * minimum allowed tag count for this
			 * device.
		 	 */
			total_openings = cgds.dev_active + cgds.dev_openings;
			*openings = cgds.dev_active;
			if (*openings < cgds.mintags)
				*openings = cgds.mintags;
			if (*openings < total_openings)
				*relsim_flags = RELSIM_ADJUST_OPENINGS;
			else {
				/*
				 * Some devices report queue full for
				 * temporary resource shortages.  For
				 * this reason, we allow a minimum
				 * tag count to be entered via a
				 * quirk entry to prevent the queue
				 * count on these devices from falling
				 * to a pessimisticly low value.  We
				 * still wait for the next successful
				 * completion, however, before queueing
				 * more transactions to the device.
				 */
				*relsim_flags = RELSIM_RELEASE_AFTER_CMDCMPLT;
			}
			*timeout = 0;
			error = ERESTART;
			if (bootverbose) {
				xpt_print(ccb->ccb_h.path, "Queue full\n");
			}
			break;
		}
		/* FALLTHROUGH */
	}
	case SCSI_STATUS_BUSY:
		/*
		 * Restart the queue after either another
		 * command completes or a 1 second timeout.
		 */
		if (bootverbose) {
			xpt_print(ccb->ccb_h.path, "Device busy\n");
		}
	 	if (ccb->ccb_h.retry_count > 0) {
	 		ccb->ccb_h.retry_count--;
			error = ERESTART;
			*relsim_flags = RELSIM_RELEASE_AFTER_TIMEOUT
				      | RELSIM_RELEASE_AFTER_CMDCMPLT;
			*timeout = 1000;
		} else {
			error = EIO;
		}
		break;
	case SCSI_STATUS_RESERV_CONFLICT:
		xpt_print(ccb->ccb_h.path, "Reservation conflict\n");
		error = EIO;
		break;
	default:
		xpt_print(ccb->ccb_h.path, "SCSI status 0x%x\n",
		    ccb->csio.scsi_status);
		error = EIO;
		break;
	}
	return (error);
}

static int
camperiphscsisenseerror(union ccb *ccb, cam_flags camflags,
			u_int32_t sense_flags,
		       int *openings, u_int32_t *relsim_flags,
		       u_int32_t *timeout, const char **action_string)
{
	struct cam_periph *periph;
	union ccb *orig_ccb = ccb;
	int error;

	periph = xpt_path_periph(ccb->ccb_h.path);
	if (periph->flags &
	    (CAM_PERIPH_RECOVERY_INPROG | CAM_PERIPH_SENSE_INPROG)) {
		/*
		 * If error recovery is already in progress, don't attempt
		 * to process this error, but requeue it unconditionally
		 * and attempt to process it once error recovery has
		 * completed.  This failed command is probably related to
		 * the error that caused the currently active error recovery
		 * action so our  current recovery efforts should also
		 * address this command.  Be aware that the error recovery
		 * code assumes that only one recovery action is in progress
		 * on a particular peripheral instance at any given time
		 * (e.g. only one saved CCB for error recovery) so it is
		 * imperitive that we don't violate this assumption.
		 */
		error = ERESTART;
	} else {
		scsi_sense_action err_action;
		struct ccb_getdev cgd;

		/*
		 * Grab the inquiry data for this device.
		 */
		xpt_setup_ccb(&cgd.ccb_h, ccb->ccb_h.path, CAM_PRIORITY_NORMAL);
		cgd.ccb_h.func_code = XPT_GDEV_TYPE;
		xpt_action((union ccb *)&cgd);

		if ((ccb->ccb_h.status & CAM_AUTOSNS_VALID) != 0)
			err_action = scsi_error_action(&ccb->csio,
						       &cgd.inq_data,
						       sense_flags);
		else if ((ccb->ccb_h.flags & CAM_DIS_AUTOSENSE) == 0)
			err_action = SS_REQSENSE;
		else
			err_action = SS_RETRY|SSQ_DECREMENT_COUNT|EIO;

		error = err_action & SS_ERRMASK;

		/*
		 * If the recovery action will consume a retry,
		 * make sure we actually have retries available.
		 */
		if ((err_action & SSQ_DECREMENT_COUNT) != 0) {
		 	if (ccb->ccb_h.retry_count > 0 &&
			    (periph->flags & CAM_PERIPH_INVALID) == 0)
		 		ccb->ccb_h.retry_count--;
			else {
				*action_string = "Retries exhausted";
				goto sense_error_done;
			}
		}

		if ((err_action & SS_MASK) >= SS_START) {
			/*
			 * Do common portions of commands that
			 * use recovery CCBs.
			 */
			orig_ccb = xpt_alloc_ccb_nowait();
			if (orig_ccb == NULL) {
				*action_string = "Can't allocate recovery CCB";
				goto sense_error_done;
			}
			/*
			 * Clear freeze flag for original request here, as
			 * this freeze will be dropped as part of ERESTART.
			 */
			ccb->ccb_h.status &= ~CAM_DEV_QFRZN;
			bcopy(ccb, orig_ccb, sizeof(*orig_ccb));
		}

		switch (err_action & SS_MASK) {
		case SS_NOP:
			*action_string = "No recovery action needed";
			error = 0;
			break;
		case SS_RETRY:
			*action_string = "Retrying command (per sense data)";
			error = ERESTART;
			break;
		case SS_FAIL:
			*action_string = "Unretryable error";
			break;
		case SS_START:
		{
			int le;
			if (SID_TYPE(&cgd.inq_data) == T_SEQUENTIAL) {
				xpt_free_ccb(orig_ccb);
				ccb->ccb_h.status |= CAM_DEV_QFRZN;
				*action_string = "Will not autostart a "
				    "sequential access device";
				err_action = SS_FAIL;
				error = EIO;
				break;
			}

			/*
			 * Send a start unit command to the device, and
			 * then retry the command.
			 */
			*action_string = "Attempting to start unit";
			periph->flags |= CAM_PERIPH_RECOVERY_INPROG;

			/*
			 * Check for removable media and set
			 * load/eject flag appropriately.
			 */
			if (SID_IS_REMOVABLE(&cgd.inq_data))
				le = TRUE;
			else
				le = FALSE;

			scsi_start_stop(&ccb->csio,
					/*retries*/1,
					camperiphdone,
					MSG_SIMPLE_Q_TAG,
					/*start*/TRUE,
					/*load/eject*/le,
					/*immediate*/FALSE,
					SSD_FULL_SIZE,
					/*timeout*/50000);
			break;
		}
		case SS_TUR:
		{
			/*
			 * Send a Test Unit Ready to the device.
			 * If the 'many' flag is set, we send 120
			 * test unit ready commands, one every half 
			 * second.  Otherwise, we just send one TUR.
			 * We only want to do this if the retry 
			 * count has not been exhausted.
			 */
			int retries;

			if ((err_action & SSQ_MANY) != 0) {
				*action_string = "Polling device for readiness";
				retries = 120;
			} else {
				*action_string = "Testing device for readiness";
				retries = 1;
			}
			periph->flags |= CAM_PERIPH_RECOVERY_INPROG;
			scsi_test_unit_ready(&ccb->csio,
					     retries,
					     camperiphdone,
					     MSG_SIMPLE_Q_TAG,
					     SSD_FULL_SIZE,
					     /*timeout*/5000);

			/*
			 * Accomplish our 500ms delay by deferring
			 * the release of our device queue appropriately.
			 */
			*relsim_flags = RELSIM_RELEASE_AFTER_TIMEOUT;
			*timeout = 500;
			break;
		}
		case SS_REQSENSE:
		{
			*action_string = "Requesting SCSI sense data";
			periph->flags |= CAM_PERIPH_SENSE_INPROG;
			/*
			 * Send a Request Sense to the device.  We
			 * assume that we are in a contingent allegiance
			 * condition so we do not tag this request.
			 */
			scsi_request_sense(&ccb->csio, /*retries*/1,
					   camperiphsensedone,
					   &orig_ccb->csio.sense_data,
					   orig_ccb->csio.sense_len,
					   CAM_TAG_ACTION_NONE,
					   /*sense_len*/SSD_FULL_SIZE,
					   /*timeout*/5000);
			break;
		}
		default:
			panic("Unhandled error action %x", err_action);
		}
		
		if ((err_action & SS_MASK) >= SS_START) {
			/*
			 * Drop the priority, so that the recovery
			 * CCB is the first to execute.  Freeze the queue
			 * after this command is sent so that we can
			 * restore the old csio and have it queued in
			 * the proper order before we release normal 
			 * transactions to the device.
			 */
			ccb->ccb_h.pinfo.priority--;
			ccb->ccb_h.flags |= CAM_DEV_QFREEZE;
			ccb->ccb_h.saved_ccb_ptr = orig_ccb;
			ccb->ccb_h.recovery_depth = 0;
			error = ERESTART;
		}

sense_error_done:
		if ((err_action & SSQ_PRINT_SENSE) != 0
		 && (ccb->ccb_h.status & CAM_AUTOSNS_VALID) != 0)
			cam_error_print(orig_ccb, CAM_ESF_ALL, CAM_EPF_ALL);
	}
	return (error);
}

/*
 * Generic error handler.  Peripheral drivers usually filter
 * out the errors that they handle in a unique mannor, then
 * call this function.
 */
int
cam_periph_error(union ccb *ccb, cam_flags camflags,
		 u_int32_t sense_flags, union ccb *save_ccb)
{
	struct cam_periph *periph;
	const char *action_string;
	cam_status  status;
	int	    frozen;
	int	    error, printed = 0;
	int         openings;
	u_int32_t   relsim_flags;
	u_int32_t   timeout = 0;

	periph = xpt_path_periph(ccb->ccb_h.path);
	action_string = NULL;
	status = ccb->ccb_h.status;
	frozen = (status & CAM_DEV_QFRZN) != 0;
	status &= CAM_STATUS_MASK;
	openings = relsim_flags = 0;

	switch (status) {
	case CAM_REQ_CMP:
		error = 0;
		break;
	case CAM_SCSI_STATUS_ERROR:
		error = camperiphscsistatuserror(ccb,
						 camflags,
						 sense_flags,
						 &openings,
						 &relsim_flags,
						 &timeout,
						 &action_string);
		break;
	case CAM_AUTOSENSE_FAIL:
		xpt_print(ccb->ccb_h.path, "AutoSense failed\n");
		error = EIO;	/* we have to kill the command */
		break;
	case CAM_ATA_STATUS_ERROR:
		if (bootverbose && printed == 0) {
			xpt_print(ccb->ccb_h.path, "ATA status error\n");
			cam_error_print(ccb, CAM_ESF_ALL, CAM_EPF_ALL);
			printed++;
		}
		/* FALLTHROUGH */
	case CAM_REQ_CMP_ERR:
		if (bootverbose && printed == 0) {
			xpt_print(ccb->ccb_h.path,
			    "Request completed with CAM_REQ_CMP_ERR\n");
			printed++;
		}
		/* FALLTHROUGH */
	case CAM_CMD_TIMEOUT:
		if (bootverbose && printed == 0) {
			xpt_print(ccb->ccb_h.path, "Command timed out\n");
			printed++;
		}
		/* FALLTHROUGH */
	case CAM_UNEXP_BUSFREE:
		if (bootverbose && printed == 0) {
			xpt_print(ccb->ccb_h.path, "Unexpected Bus Free\n");
			printed++;
		}
		/* FALLTHROUGH */
	case CAM_UNCOR_PARITY:
		if (bootverbose && printed == 0) {
			xpt_print(ccb->ccb_h.path,
			    "Uncorrected parity error\n");
			printed++;
		}
		/* FALLTHROUGH */
	case CAM_DATA_RUN_ERR:
		if (bootverbose && printed == 0) {
			xpt_print(ccb->ccb_h.path, "Data overrun\n");
			printed++;
		}
		/* decrement the number of retries */
		if (ccb->ccb_h.retry_count > 0 &&
		    (periph->flags & CAM_PERIPH_INVALID) == 0) {
			ccb->ccb_h.retry_count--;
			error = ERESTART;
		} else {
			action_string = "Retries exhausted";
			error = EIO;
		}
		break;
	case CAM_UA_ABORT:
	case CAM_UA_TERMIO:
	case CAM_MSG_REJECT_REC:
		/* XXX Don't know that these are correct */
		error = EIO;
		break;
	case CAM_SEL_TIMEOUT:
		if ((camflags & CAM_RETRY_SELTO) != 0) {
			if (ccb->ccb_h.retry_count > 0 &&
			    (periph->flags & CAM_PERIPH_INVALID) == 0) {

				ccb->ccb_h.retry_count--;
				error = ERESTART;
				if (bootverbose && printed == 0) {
					xpt_print(ccb->ccb_h.path,
					    "Selection timeout\n");
					printed++;
				}

				/*
				 * Wait a bit to give the device
				 * time to recover before we try again.
				 */
				relsim_flags = RELSIM_RELEASE_AFTER_TIMEOUT;
				timeout = periph_selto_delay;
				break;
			}
			action_string = "Retries exhausted";
		}
		/* FALLTHROUGH */
	case CAM_DEV_NOT_THERE:
	{
		struct cam_path *newpath;
		lun_id_t lun_id;

		error = ENXIO;

		/*
		 * For a selection timeout, we consider all of the LUNs on
		 * the target to be gone.  If the status is CAM_DEV_NOT_THERE,
		 * then we only get rid of the device(s) specified by the
		 * path in the original CCB.
		 */
		if (status == CAM_DEV_NOT_THERE)
			lun_id = xpt_path_lun_id(ccb->ccb_h.path);
		else
			lun_id = CAM_LUN_WILDCARD;

		/* Should we do more if we can't create the path?? */
		if (xpt_create_path(&newpath, periph,
				    xpt_path_path_id(ccb->ccb_h.path),
				    xpt_path_target_id(ccb->ccb_h.path),
				    lun_id) != CAM_REQ_CMP) 
			break;

		/*
		 * Let peripheral drivers know that this device has gone
		 * away.
		 */
		xpt_async(AC_LOST_DEVICE, newpath, NULL);
		xpt_free_path(newpath);
		break;
	}
	case CAM_REQ_INVALID:
	case CAM_PATH_INVALID:
	case CAM_NO_HBA:
	case CAM_PROVIDE_FAIL:
	case CAM_REQ_TOO_BIG:
	case CAM_LUN_INVALID:
	case CAM_TID_INVALID:
		error = EINVAL;
		break;
	case CAM_SCSI_BUS_RESET:
	case CAM_BDR_SENT:
		/*
		 * Commands that repeatedly timeout and cause these
		 * kinds of error recovery actions, should return
		 * CAM_CMD_TIMEOUT, which allows us to safely assume
		 * that this command was an innocent bystander to
		 * these events and should be unconditionally
		 * retried.
		 */
		if (bootverbose && printed == 0) {
			xpt_print_path(ccb->ccb_h.path);
			if (status == CAM_BDR_SENT)
				printf("Bus Device Reset sent\n");
			else
				printf("Bus Reset issued\n");
			printed++;
		}
		/* FALLTHROUGH */
	case CAM_REQUEUE_REQ:
		/* Unconditional requeue */
		if (bootverbose && printed == 0) {
			xpt_print(ccb->ccb_h.path, "Request requeued\n");
			printed++;
		}
		if ((periph->flags & CAM_PERIPH_INVALID) == 0)
			error = ERESTART;
		else {
			action_string = "Retries exhausted";
			error = EIO;
		}
		break;
	case CAM_RESRC_UNAVAIL:
		/* Wait a bit for the resource shortage to abate. */
		timeout = periph_noresrc_delay;
		/* FALLTHROUGH */
	case CAM_BUSY:
		if (timeout == 0) {
			/* Wait a bit for the busy condition to abate. */
			timeout = periph_busy_delay;
		}
		relsim_flags = RELSIM_RELEASE_AFTER_TIMEOUT;
		/* FALLTHROUGH */
	default:
		/* decrement the number of retries */
		if (ccb->ccb_h.retry_count > 0 &&
		    (periph->flags & CAM_PERIPH_INVALID) == 0) {
			ccb->ccb_h.retry_count--;
			error = ERESTART;
			if (bootverbose && printed == 0) {
				xpt_print(ccb->ccb_h.path, "CAM status 0x%x\n",
				    status);
				printed++;
			}
		} else {
			error = EIO;
			action_string = "Retries exhausted";
		}
		break;
	}

	/*
	 * If we have and error and are booting verbosely, whine
	 * *unless* this was a non-retryable selection timeout.
	 */
	if (error != 0 && bootverbose &&
	    !(status == CAM_SEL_TIMEOUT && (camflags & CAM_RETRY_SELTO) == 0)) {
		if (error != ERESTART) {
			if (action_string == NULL)
				action_string = "Unretryable error";
			xpt_print(ccb->ccb_h.path, "Error %d, %s\n",
			    error, action_string);
		} else if (action_string != NULL)
			xpt_print(ccb->ccb_h.path, "%s\n", action_string);
		else
			xpt_print(ccb->ccb_h.path, "Retrying command\n");
	}

	/* Attempt a retry */
	if (error == ERESTART || error == 0) {
		if (frozen != 0)
			ccb->ccb_h.status &= ~CAM_DEV_QFRZN;
		if (error == ERESTART)
			xpt_action(ccb);
		if (frozen != 0)
			cam_release_devq(ccb->ccb_h.path,
					 relsim_flags,
					 openings,
					 timeout,
					 /*getcount_only*/0);
	}

	return (error);
}