xref: /src/sys/dev/isa/wds.c

/*	$NetBSD: wds.c,v 1.25 1997/11/04 06:16:13 thorpej Exp $	*/

#undef WDSDIAG
#ifdef DDB
#define	integrate
#else
#define	integrate	static inline
#endif

/*
 * XXX
 * sense data
 * aborts
 * resets
 */

/*-
 * Copyright (c) 1997 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
 * NASA Ames Research Center.
 *
 * 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 acknowledgement:
 *	This product includes software developed by the NetBSD
 *	Foundation, Inc. and its contributors.
 * 4. Neither the name of The NetBSD Foundation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

/*
 * Copyright (c) 1994, 1995 Julian Highfield.  All rights reserved.
 * Portions copyright (c) 1994, 1996, 1997
 *	Charles M. Hannum.  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.
 * 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 acknowledgement:
 *	This product includes software developed by Julian Highfield.
 * 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.
 */

/*
 * This driver is for the WD7000 family of SCSI controllers:
 *   the WD7000-ASC, a bus-mastering DMA controller,
 *   the WD7000-FASST2, an -ASC with new firmware and scatter-gather,
 *   and the WD7000-ASE, which was custom manufactured for Apollo
 *      workstations and seems to include an -ASC as well as floppy
 *      and ESDI interfaces.
 *
 * Loosely based on Theo Deraadt's unfinished attempt.
 */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/errno.h>
#include <sys/ioctl.h>
#include <sys/device.h>
#include <sys/malloc.h>
#include <sys/buf.h>
#include <sys/proc.h>
#include <sys/user.h>

#include <machine/bus.h>
#include <machine/intr.h>

#include <dev/scsipi/scsi_all.h>
#include <dev/scsipi/scsipi_all.h>
#include <dev/scsipi/scsiconf.h>

#include <dev/isa/isavar.h>
#include <dev/isa/isadmavar.h>

#include <dev/isa/wdsreg.h>

#define	WDS_ISA_IOSIZE	8

#ifndef DDB
#define Debugger() panic("should call debugger here (wds.c)")
#endif /* ! DDB */

#define	WDS_MAXXFER	((WDS_NSEG - 1) << PGSHIFT)

#define WDS_MBX_SIZE	16

#define WDS_SCB_MAX	32
#define	SCB_HASH_SIZE	32	/* hash table size for phystokv */
#define	SCB_HASH_SHIFT	9
#define	SCB_HASH(x)	((((long)(x))>>SCB_HASH_SHIFT) & (SCB_HASH_SIZE - 1))

#define	wds_nextmbx(wmb, mbx, mbio) \
	if ((wmb) == &(mbx)->mbio[WDS_MBX_SIZE - 1])	\
		(wmb) = &(mbx)->mbio[0];		\
	else						\
		(wmb)++;

struct wds_mbx {
	struct wds_mbx_out mbo[WDS_MBX_SIZE];
	struct wds_mbx_in mbi[WDS_MBX_SIZE];
	struct wds_mbx_out *cmbo;	/* Collection Mail Box out */
	struct wds_mbx_out *tmbo;	/* Target Mail Box out */
	struct wds_mbx_in *tmbi;	/* Target Mail Box in */
};

struct wds_softc {
	struct device sc_dev;

	bus_space_tag_t sc_iot;
	bus_space_handle_t sc_ioh;
	bus_dma_tag_t sc_dmat;
	bus_dmamap_t sc_dmamap_mbox;	/* maps the mailbox */
	void *sc_ih;

	struct wds_mbx *sc_mbx;
#define	wmbx	(sc->sc_mbx)
	struct wds_scb *sc_scbhash[SCB_HASH_SIZE];
	TAILQ_HEAD(, wds_scb) sc_free_scb, sc_waiting_scb;
	int sc_numscbs, sc_mbofull;
	struct scsipi_link sc_link;	/* prototype for subdevs */

	LIST_HEAD(, scsipi_xfer) sc_queue;
	struct scsipi_xfer *sc_queuelast;

	int sc_revision;
	int sc_maxsegs;
};

struct wds_probe_data {
#ifdef notyet
	int sc_irq, sc_drq;
#endif
	int sc_scsi_dev;
};

integrate void
	wds_wait __P((bus_space_tag_t, bus_space_handle_t, int, int, int));
int     wds_cmd __P((bus_space_tag_t, bus_space_handle_t, u_char *, int));
integrate void wds_finish_scbs __P((struct wds_softc *));
int     wdsintr __P((void *));
integrate void wds_reset_scb __P((struct wds_softc *, struct wds_scb *));
void    wds_free_scb __P((struct wds_softc *, struct wds_scb *));
integrate int wds_init_scb __P((struct wds_softc *, struct wds_scb *));
struct	wds_scb *wds_get_scb __P((struct wds_softc *, int));
struct	wds_scb *wds_scb_phys_kv __P((struct wds_softc *, u_long));
void	wds_queue_scb __P((struct wds_softc *, struct wds_scb *));
void	wds_collect_mbo __P((struct wds_softc *));
void	wds_start_scbs __P((struct wds_softc *));
void    wds_done __P((struct wds_softc *, struct wds_scb *, u_char));
int	wds_find __P((bus_space_tag_t, bus_space_handle_t, struct wds_probe_data *));
void	wds_attach __P((struct wds_softc *, struct wds_probe_data *));
void	wds_init __P((struct wds_softc *, int));
void	wds_inquire_setup_information __P((struct wds_softc *));
void    wdsminphys __P((struct buf *));
int     wds_scsi_cmd __P((struct scsipi_xfer *));
void	wds_sense  __P((struct wds_softc *, struct wds_scb *));
int	wds_poll __P((struct wds_softc *, struct scsipi_xfer *, int));
int	wds_ipoll __P((struct wds_softc *, struct wds_scb *, int));
void	wds_timeout __P((void *));
int	wds_create_scbs __P((struct wds_softc *, void *, size_t));
void	wds_enqueue __P((struct wds_softc *, struct scsipi_xfer *, int));
struct scsipi_xfer *wds_dequeue __P((struct wds_softc *));

struct scsipi_adapter wds_switch = {
	wds_scsi_cmd,
	wdsminphys,
	0,
	0,
};

/* the below structure is so we have a default dev struct for our link struct */
struct scsipi_device wds_dev = {
	NULL,			/* Use default error handler */
	NULL,			/* have a queue, served by this */
	NULL,			/* have no async handler */
	NULL,			/* Use default 'done' routine */
};

int	wdsprobe __P((struct device *, void *, void *));
void	wdsattach __P((struct device *, struct device *, void *));

struct cfattach wds_ca = {
	sizeof(struct wds_softc), wdsprobe, wdsattach
};

struct cfdriver wds_cd = {
	NULL, "wds", DV_DULL
};

#define	WDS_ABORT_TIMEOUT	2000	/* time to wait for abort (mSec) */

/* XXX Should put this in a better place. */
#define	offsetof(type, member)	((size_t)(&((type *)0)->member))

/*
 * Insert a scsipi_xfer into the software queue.  We overload xs->free_list
 * to avoid having to allocate additional resources (since we're used
 * only during resource shortages anyhow.
 */
void
wds_enqueue(sc, xs, infront)
	struct wds_softc *sc;
	struct scsipi_xfer *xs;
	int infront;
{

	if (infront || sc->sc_queue.lh_first == NULL) {
		if (sc->sc_queue.lh_first == NULL)
			sc->sc_queuelast = xs;
		LIST_INSERT_HEAD(&sc->sc_queue, xs, free_list);
		return;
	}

	LIST_INSERT_AFTER(sc->sc_queuelast, xs, free_list);
	sc->sc_queuelast = xs;
}

/*
 * Pull a scsipi_xfer off the front of the software queue.
 */
struct scsipi_xfer *
wds_dequeue(sc)
	struct wds_softc *sc;
{
	struct scsipi_xfer *xs;

	xs = sc->sc_queue.lh_first;
	LIST_REMOVE(xs, free_list);

	if (sc->sc_queue.lh_first == NULL)
		sc->sc_queuelast = NULL;

	return (xs);
}

integrate void
wds_wait(iot, ioh, port, mask, val)
	bus_space_tag_t iot;
	bus_space_handle_t ioh;
	int port;
	int mask, val;
{

	while ((bus_space_read_1(iot, ioh, port) & mask) != val)
		;
}

/*
 * Write a command to the board's I/O ports.
 */
int
wds_cmd(iot, ioh, ibuf, icnt)
	bus_space_tag_t iot;
	bus_space_handle_t ioh;
	u_char *ibuf;
	int icnt;
{
	u_char c;

	wds_wait(iot, ioh, WDS_STAT, WDSS_RDY, WDSS_RDY);

	while (icnt--) {
		bus_space_write_1(iot, ioh, WDS_CMD, *ibuf++);
		wds_wait(iot, ioh, WDS_STAT, WDSS_RDY, WDSS_RDY);
		c = bus_space_read_1(iot, ioh, WDS_STAT);
		if (c & WDSS_REJ)
			return 1;
	}

	return 0;
}

/*
 * Check for the presence of a WD7000 SCSI controller.
 */
int
wdsprobe(parent, match, aux)
	struct device *parent;
	void *match, *aux;
{
	struct isa_attach_args *ia = aux;
	bus_space_tag_t iot = ia->ia_iot;
	bus_space_handle_t ioh;
	struct wds_probe_data wpd;
	int rv;

	/* Disallow wildcarded i/o address. */
	if (ia->ia_iobase == ISACF_PORT_DEFAULT)
		return (0);

	if (bus_space_map(iot, ia->ia_iobase, WDS_ISA_IOSIZE, 0, &ioh))
		return (0);

	rv = wds_find(iot, ioh, &wpd);

	bus_space_unmap(iot, ioh, WDS_ISA_IOSIZE);

	if (rv) {
#ifdef notyet
		if (ia->ia_irq != -1 && ia->ia_irq != wpd.sc_irq)
			return (0);
		if (ia->ia_drq != -1 && ia->ia_drq != wpd.sc_drq)
			return (0);
		ia->ia_irq = wpd.sc_irq;
		ia->ia_drq = wpd.sc_drq;
#else
		if (ia->ia_irq == -1)
			return (0);
		if (ia->ia_drq == -1)
			return (0);
#endif
		ia->ia_msize = 0;
		ia->ia_iosize = WDS_ISA_IOSIZE;
	}
	return (rv);
}

/*
 * Attach all available units.
 */
void
wdsattach(parent, self, aux)
	struct device *parent, *self;
	void *aux;
{
	struct isa_attach_args *ia = aux;
	struct wds_softc *sc = (void *)self;
	bus_space_tag_t iot = ia->ia_iot;
	bus_space_handle_t ioh;
	struct wds_probe_data wpd;
	isa_chipset_tag_t ic = ia->ia_ic;

	printf("\n");

	if (bus_space_map(iot, ia->ia_iobase, WDS_ISA_IOSIZE, 0, &ioh)) {
		printf("%s: can't map i/o space\n", sc->sc_dev.dv_xname);
		return;
	}

	sc->sc_iot = iot;
	sc->sc_ioh = ioh;
	sc->sc_dmat = ia->ia_dmat;
	if (!wds_find(iot, ioh, &wpd)) {
		printf("%s: wds_find failed\n", sc->sc_dev.dv_xname);
		return;
	}

	bus_space_write_1(iot, ioh, WDS_HCR, WDSH_DRQEN);
#ifdef notyet
	if (wpd.sc_drq != -1)
		isa_dmacascade(parent, wpd.sc_drq);

	sc->sc_ih = isa_intr_establish(ic, wpd.sc_irq, IST_EDGE, IPL_BIO,
	    wdsintr, sc);
#else
	if (ia->ia_drq != -1)
		isa_dmacascade(parent, ia->ia_drq);

	sc->sc_ih = isa_intr_establish(ic, ia->ia_irq, IST_EDGE, IPL_BIO,
	    wdsintr, sc);
#endif
	if (sc->sc_ih == NULL) {
		printf("%s: couldn't establish interrupt\n",
		    sc->sc_dev.dv_xname);
		return;
	}

	wds_attach(sc, &wpd);
}

void
wds_attach(sc, wpd)
	struct wds_softc *sc;
	struct wds_probe_data *wpd;
{

	TAILQ_INIT(&sc->sc_free_scb);
	TAILQ_INIT(&sc->sc_waiting_scb);
	LIST_INIT(&sc->sc_queue);

	wds_init(sc, 0);
	wds_inquire_setup_information(sc);

	/*
	 * fill in the prototype scsipi_link.
	 */
	sc->sc_link.scsipi_scsi.channel = SCSI_CHANNEL_ONLY_ONE;
	sc->sc_link.adapter_softc = sc;
	sc->sc_link.scsipi_scsi.adapter_target = wpd->sc_scsi_dev;
	sc->sc_link.adapter = &wds_switch;
	sc->sc_link.device = &wds_dev;
	/* XXX */
	/* I don't think the -ASE can handle openings > 1. */
	/* It gives Vendor Error 26 whenever I try it.     */
	sc->sc_link.openings = 1;
	sc->sc_link.scsipi_scsi.max_target = 7;
	sc->sc_link.type = BUS_SCSI;

	/*
	 * ask the adapter what subunits are present
	 */
	config_found(&sc->sc_dev, &sc->sc_link, scsiprint);
}

integrate void
wds_finish_scbs(sc)
	struct wds_softc *sc;
{
	struct wds_mbx_in *wmbi;
	struct wds_scb *scb;
	int i;

	wmbi = wmbx->tmbi;

	if (wmbi->stat == WDS_MBI_FREE) {
		for (i = 0; i < WDS_MBX_SIZE; i++) {
			if (wmbi->stat != WDS_MBI_FREE) {
				printf("%s: mbi not in round-robin order\n",
				    sc->sc_dev.dv_xname);
				goto AGAIN;
			}
			wds_nextmbx(wmbi, wmbx, mbi);
		}
#ifdef WDSDIAGnot
		printf("%s: mbi interrupt with no full mailboxes\n",
		    sc->sc_dev.dv_xname);
#endif
		return;
	}

AGAIN:
	do {
		scb = wds_scb_phys_kv(sc, phystol(wmbi->scb_addr));
		if (!scb) {
			printf("%s: bad mbi scb pointer; skipping\n",
			    sc->sc_dev.dv_xname);
			goto next;
		}

#ifdef WDSDEBUG
		if (wds_debug) {
			u_char *cp = &scb->scsipi_cmd;
			printf("op=%x %x %x %x %x %x\n",
			    cp[0], cp[1], cp[2], cp[3], cp[4], cp[5]);
			printf("stat %x for mbi addr = 0x%08x, ",
			    wmbi->stat, wmbi);
			printf("scb addr = 0x%x\n", scb);
		}
#endif /* WDSDEBUG */

		untimeout(wds_timeout, scb);
		wds_done(sc, scb, wmbi->stat);

	next:
		wmbi->stat = WDS_MBI_FREE;
		wds_nextmbx(wmbi, wmbx, mbi);
	} while (wmbi->stat != WDS_MBI_FREE);

	wmbx->tmbi = wmbi;
}

/*
 * Process an interrupt.
 */
int
wdsintr(arg)
	void *arg;
{
	struct wds_softc *sc = arg;
	bus_space_tag_t iot = sc->sc_iot;
	bus_space_handle_t ioh = sc->sc_ioh;
	u_char c;

	/* Was it really an interrupt from the board? */
	if ((bus_space_read_1(iot, ioh, WDS_STAT) & WDSS_IRQ) == 0)
		return 0;

	/* Get the interrupt status byte. */
	c = bus_space_read_1(iot, ioh, WDS_IRQSTAT) & WDSI_MASK;

	/* Acknowledge (which resets) the interrupt. */
	bus_space_write_1(iot, ioh, WDS_IRQACK, 0x00);

	switch (c) {
	case WDSI_MSVC:
		wds_finish_scbs(sc);
		break;

	case WDSI_MFREE:
		wds_start_scbs(sc);
		break;

	default:
		printf("%s: unrecognized interrupt type %02x",
		    sc->sc_dev.dv_xname, c);
		break;
	}

	return 1;
}

integrate void
wds_reset_scb(sc, scb)
	struct wds_softc *sc;
	struct wds_scb *scb;
{

	scb->flags = 0;
}

/*
 * Free the command structure, the outgoing mailbox and the data buffer.
 */
void
wds_free_scb(sc, scb)
	struct wds_softc *sc;
	struct wds_scb *scb;
{
	int s;

	s = splbio();

	wds_reset_scb(sc, scb);
	TAILQ_INSERT_HEAD(&sc->sc_free_scb, scb, chain);

	/*
	 * If there were none, wake anybody waiting for one to come free,
	 * starting with queued entries.
	 */
	if (scb->chain.tqe_next == 0)
		wakeup(&sc->sc_free_scb);

	splx(s);
}

integrate int
wds_init_scb(sc, scb)
	struct wds_softc *sc;
	struct wds_scb *scb;
{
	bus_dma_tag_t dmat = sc->sc_dmat;
	int hashnum, error;

	/*
	 * XXX Should we put a DIAGNOSTIC check for multiple
	 * XXX SCB inits here?
	 */

	bzero(scb, sizeof(struct wds_scb));

	/*
	 * Create DMA maps for this SCB.
	 */
	error = bus_dmamap_create(dmat, sizeof(struct wds_scb), 1,
	    sizeof(struct wds_scb), 0, BUS_DMA_NOWAIT, &scb->dmamap_self);
	if (error) {
		printf("%s: can't create scb dmamap_self\n",
		    sc->sc_dev.dv_xname);
		return (error);
	}

	error = bus_dmamap_create(dmat, WDS_MAXXFER, WDS_NSEG, WDS_MAXXFER,
	    0, BUS_DMA_NOWAIT|BUS_DMA_ALLOCNOW, &scb->dmamap_xfer);
	if (error) {
		printf("%s: can't create scb dmamap_xfer\n",
		    sc->sc_dev.dv_xname);
		bus_dmamap_destroy(dmat, scb->dmamap_self);
		return (error);
	}

	/*
	 * Load the permanent DMA maps.
	 */
	error = bus_dmamap_load(dmat, scb->dmamap_self, scb,
	    sizeof(struct wds_scb), NULL, BUS_DMA_NOWAIT);
	if (error) {
		printf("%s: can't load scb dmamap_self\n",
		    sc->sc_dev.dv_xname);
		bus_dmamap_destroy(dmat, scb->dmamap_self);
		bus_dmamap_destroy(dmat, scb->dmamap_xfer);
		return (error);
	}

	/*
	 * put in the phystokv hash table
	 * Never gets taken out.
	 */
	scb->hashkey = scb->dmamap_self->dm_segs[0].ds_addr;
	hashnum = SCB_HASH(scb->hashkey);
	scb->nexthash = sc->sc_scbhash[hashnum];
	sc->sc_scbhash[hashnum] = scb;
	wds_reset_scb(sc, scb);
	return (0);
}

/*
 * Create a set of scbs and add them to the free list.
 */
int
wds_create_scbs(sc, mem, size)
	struct wds_softc *sc;
	void *mem;
	size_t size;
{
	bus_dma_segment_t seg;
	struct wds_scb *scb;
	int rseg, error;

	if (sc->sc_numscbs >= WDS_SCB_MAX)
		return (0);

	if ((scb = mem) != NULL)
		goto have_mem;

	size = NBPG;
	error = bus_dmamem_alloc(sc->sc_dmat, size, NBPG, 0, &seg, 1, &rseg,
	    BUS_DMA_NOWAIT);
	if (error) {
		printf("%s: can't allocate memory for scbs\n",
		    sc->sc_dev.dv_xname);
		return (error);
	}

	error = bus_dmamem_map(sc->sc_dmat, &seg, rseg, size,
	    (caddr_t *)&scb, BUS_DMA_NOWAIT|BUS_DMAMEM_NOSYNC);
	if (error) {
		printf("%s: can't map memory for scbs\n",
		    sc->sc_dev.dv_xname);
		bus_dmamem_free(sc->sc_dmat, &seg, rseg);
		return (error);
	}

 have_mem:
	bzero(scb, size);
	while (size > sizeof(struct wds_scb) && sc->sc_numscbs < WDS_SCB_MAX) {
		error = wds_init_scb(sc, scb);
		if (error) {
			printf("%s: can't initialize scb\n",
			    sc->sc_dev.dv_xname);
			return (error);
		}
		TAILQ_INSERT_TAIL(&sc->sc_free_scb, scb, chain);
		(caddr_t)scb += ALIGN(sizeof(struct wds_scb));
		size -= ALIGN(sizeof(struct wds_scb));
		sc->sc_numscbs++;
	}

	return (0);
}

/*
 * Get a free scb
 *
 * If there are none, see if we can allocate a new one.  If so, put it in
 * the hash table too otherwise either return an error or sleep.
 */
struct wds_scb *
wds_get_scb(sc, flags)
	struct wds_softc *sc;
	int flags;
{
	struct wds_scb *scb;
	int s;

	s = splbio();

	/*
	 * If we can and have to, sleep waiting for one to come free
	 * but only if we can't allocate a new one.
	 */
	for (;;) {
		scb = sc->sc_free_scb.tqh_first;
		if (scb) {
			TAILQ_REMOVE(&sc->sc_free_scb, scb, chain);
			break;
		}
		if (sc->sc_numscbs < WDS_SCB_MAX) {
			/*
			 * wds_create_scbs() might have managed to create
			 * one before it failed.  If so, don't abort,
			 * just grab it and continue to hobble along.
			 */
			if (wds_create_scbs(sc, NULL, 0) != 0 &&
			    sc->sc_free_scb.tqh_first == NULL) {
				printf("%s: can't allocate scbs\n",
				    sc->sc_dev.dv_xname);
				goto out;
			}
			continue;
		}
		if ((flags & SCSI_NOSLEEP) != 0)
			goto out;
		tsleep(&sc->sc_free_scb, PRIBIO, "wdsscb", 0);
	}

	scb->flags |= SCB_ALLOC;

out:
	splx(s);
	return (scb);
}

struct wds_scb *
wds_scb_phys_kv(sc, scb_phys)
	struct wds_softc *sc;
	u_long scb_phys;
{
	int hashnum = SCB_HASH(scb_phys);
	struct wds_scb *scb = sc->sc_scbhash[hashnum];

	while (scb) {
		if (scb->hashkey == scb_phys)
			break;
		/* XXX Check to see if it matches the sense command block. */
		if (scb->hashkey == (scb_phys - sizeof(struct wds_cmd)))
			break;
		scb = scb->nexthash;
	}
	return (scb);
}

/*
 * Queue a SCB to be sent to the controller, and send it if possible.
 */
void
wds_queue_scb(sc, scb)
	struct wds_softc *sc;
	struct wds_scb *scb;
{

	TAILQ_INSERT_TAIL(&sc->sc_waiting_scb, scb, chain);
	wds_start_scbs(sc);
}

/*
 * Garbage collect mailboxes that are no longer in use.
 */
void
wds_collect_mbo(sc)
	struct wds_softc *sc;
{
	struct wds_mbx_out *wmbo;	/* Mail Box Out pointer */
#ifdef WDSDIAG
	struct wds_scb *scb;
#endif

	wmbo = wmbx->cmbo;

	while (sc->sc_mbofull > 0) {
		if (wmbo->cmd != WDS_MBO_FREE)
			break;

#ifdef WDSDIAG
		scb = wds_scb_phys_kv(sc, phystol(wmbo->scb_addr));
		scb->flags &= ~SCB_SENDING;
#endif

		--sc->sc_mbofull;
		wds_nextmbx(wmbo, wmbx, mbo);
	}

	wmbx->cmbo = wmbo;
}

/*
 * Send as many SCBs as we have empty mailboxes for.
 */
void
wds_start_scbs(sc)
	struct wds_softc *sc;
{
	bus_space_tag_t iot = sc->sc_iot;
	bus_space_handle_t ioh = sc->sc_ioh;
	struct wds_mbx_out *wmbo;	/* Mail Box Out pointer */
	struct wds_scb *scb;
	u_char c;

	wmbo = wmbx->tmbo;

	while ((scb = sc->sc_waiting_scb.tqh_first) != NULL) {
		if (sc->sc_mbofull >= WDS_MBX_SIZE) {
			wds_collect_mbo(sc);
			if (sc->sc_mbofull >= WDS_MBX_SIZE) {
				c = WDSC_IRQMFREE;
				wds_cmd(iot, ioh, &c, sizeof c);
				break;
			}
		}

		TAILQ_REMOVE(&sc->sc_waiting_scb, scb, chain);
#ifdef WDSDIAG
		scb->flags |= SCB_SENDING;
#endif

		/* Link scb to mbo. */
		if (scb->flags & SCB_SENSE)
			ltophys(scb->dmamap_self->dm_segs[0].ds_addr +
			    offsetof(struct wds_scb, sense), wmbo->scb_addr);
		else
			ltophys(scb->dmamap_self->dm_segs[0].ds_addr +
			    offsetof(struct wds_scb, cmd), wmbo->scb_addr);
		/* XXX What about aborts? */
		wmbo->cmd = WDS_MBO_START;

		/* Tell the card to poll immediately. */
		c = WDSC_MSTART(wmbo - wmbx->mbo);
		wds_cmd(sc->sc_iot, sc->sc_ioh, &c, sizeof c);

		if ((scb->flags & SCB_POLLED) == 0)
			timeout(wds_timeout, scb, (scb->timeout * hz) / 1000);

		++sc->sc_mbofull;
		wds_nextmbx(wmbo, wmbx, mbo);
	}

	wmbx->tmbo = wmbo;
}

/*
 * Process the result of a SCSI command.
 */
void
wds_done(sc, scb, stat)
	struct wds_softc *sc;
	struct wds_scb *scb;
	u_char stat;
{
	bus_dma_tag_t dmat = sc->sc_dmat;
	struct scsipi_xfer *xs = scb->xs;

	/* XXXXX */

	/* Don't release the SCB if it was an internal command. */
	if (xs == 0) {
		scb->flags |= SCB_DONE;
		return;
	}

	/* Sense handling. */
	if (xs->error == XS_SENSE) {
		bcopy(&scb->sense_data, &xs->sense.scsi_sense,
			sizeof (struct scsipi_sense_data));
	} else {
		/*
		 * If we were a data transfer, unload the map that described
		 * the data buffer.
		 */
		if (xs->datalen) {
			bus_dmamap_sync(dmat, scb->dmamap_xfer,
			    (xs->flags & SCSI_DATA_IN) ? BUS_DMASYNC_POSTREAD :
			    BUS_DMASYNC_POSTWRITE);
			bus_dmamap_unload(dmat, scb->dmamap_xfer);
		}
		if (xs->error == XS_NOERROR) {
			/* If all went well, or an error is acceptable. */
			if (stat == WDS_MBI_OK) {
				/* OK, set the result */
				xs->resid = 0;
			} else {
				/* Check the mailbox status. */
				switch (stat) {
				case WDS_MBI_OKERR:
					/*
					 * SCSI error recorded in scb,
					 * counts as WDS_MBI_OK
					 */
					switch (scb->cmd.venderr) {
					case 0x00:
						printf("%s: Is this "
						    "an error?\n",
						    sc->sc_dev.dv_xname);
						/* Experiment. */
						xs->error = XS_DRIVER_STUFFUP;
						break;
					case 0x01:
#if 0
						printf("%s: OK, see SCSI "
						    "error field.\n",
						    sc->sc_dev.dv_xname);
#endif
						if (scb->cmd.stat ==
						    SCSI_CHECK) {
							/* Do sense. */
							wds_sense(sc, scb);
							return;
						} else if (scb->cmd.stat ==
						    SCSI_BUSY) {
							xs->error = XS_BUSY;
						}
						break;
					case 0x40:
#if 0
						printf("%s: DMA underrun!\n",
						    sc->sc_dev.dv_xname);
#endif
						/*
						 * Hits this if the target
						 * returns fewer that datalen
						 * bytes (eg my CD-ROM, which
						 * returns a short version
						 * string, or if DMA is
						 * turned off etc.
						 */
						xs->resid = 0;
						break;
					default:
						printf("%s: VENDOR ERROR "
						    "%02x, scsi %02x\n",
						    sc->sc_dev.dv_xname,
						    scb->cmd.venderr,
						    scb->cmd.stat);
						/* Experiment. */
						xs->error = XS_DRIVER_STUFFUP;
						break;
					}
					break;
				case WDS_MBI_ETIME:
					/*
					 * The documentation isn't clear on
					 * what conditions might generate this,
					 * but selection timeouts are the only
					 * one I can think of.
					 */
					xs->error = XS_SELTIMEOUT;
					break;
				case WDS_MBI_ERESET:
				case WDS_MBI_ETARCMD:
				case WDS_MBI_ERESEL:
				case WDS_MBI_ESEL:
				case WDS_MBI_EABORT:
				case WDS_MBI_ESRESET:
				case WDS_MBI_EHRESET:
					xs->error = XS_DRIVER_STUFFUP;
					break;
				}
			}
		} /* else sense */
	} /* XS_NOERROR */

	wds_free_scb(sc, scb);
	xs->flags |= ITSDONE;
	scsipi_done(xs);

	/*
	 * If there are queue entries in the software queue, try to
	 * run the first one.  We should be more or less guaranteed
	 * to succeed, since we just freed a CCB.
	 *
	 * NOTE: wds_scsi_cmd() relies on our calling it with
	 * the first entry in the queue.
	 */
	if ((xs = sc->sc_queue.lh_first) != NULL)
		(void) wds_scsi_cmd(xs);
}

int
wds_find(iot, ioh, sc)
	bus_space_tag_t iot;
	bus_space_handle_t ioh;
	struct wds_probe_data *sc;
{
	int i;

	/* XXXXX */

	/*
	 * Sending a command causes the CMDRDY bit to clear.
 	 */
	for (i = 5; i; i--) {
		if ((bus_space_read_1(iot, ioh, WDS_STAT) & WDSS_RDY) != 0)
			break;
		delay(100);
	}
	if (!i)
		return 0;

	bus_space_write_1(iot, ioh, WDS_CMD, WDSC_NOOP);
	if ((bus_space_read_1(iot, ioh, WDS_STAT) & WDSS_RDY) != 0)
		return 0;

	bus_space_write_1(iot, ioh, WDS_HCR, WDSH_SCSIRESET|WDSH_ASCRESET);
	delay(10000);
	bus_space_write_1(iot, ioh, WDS_HCR, 0x00);
	delay(500000);
	wds_wait(iot, ioh, WDS_STAT, WDSS_RDY, WDSS_RDY);
	if (bus_space_read_1(iot, ioh, WDS_IRQSTAT) != 1)
		if (bus_space_read_1(iot, ioh, WDS_IRQSTAT) != 7)
			return 0;

	for (i = 2000; i; i--) {
		if ((bus_space_read_1(iot, ioh, WDS_STAT) & WDSS_RDY) != 0)
			break;
		delay(100);
	}
	if (!i)
		return 0;

	if (sc) {
#ifdef notyet
		sc->sc_irq = ...;
		sc->sc_drq = ...;
#endif
		/* XXX Can we do this better? */
		sc->sc_scsi_dev = 7;
	}

	return 1;
}

/*
 * Initialise the board and driver.
 */
void
wds_init(sc, isreset)
	struct wds_softc *sc;
	int isreset;
{
	bus_space_tag_t iot = sc->sc_iot;
	bus_space_handle_t ioh = sc->sc_ioh;
	bus_dma_segment_t seg;
	struct wds_setup init;
	u_char c;
	int i, rseg;

	if (isreset)
		goto doinit;

	/*
	 * Allocate the mailbox.
	 */
	if (bus_dmamem_alloc(sc->sc_dmat, NBPG, NBPG, 0, &seg, 1,
	    &rseg, BUS_DMA_NOWAIT) ||
	    bus_dmamem_map(sc->sc_dmat, &seg, rseg, NBPG,
	    (caddr_t *)&wmbx, BUS_DMA_NOWAIT|BUS_DMAMEM_NOSYNC))
		panic("wds_init: can't create or map mailbox");

	/*
	 * Since DMA memory allocation is always rounded up to a
	 * page size, create some scbs from the leftovers.
	 */
	if (wds_create_scbs(sc, ((caddr_t)wmbx) +
	    ALIGN(sizeof(struct wds_mbx)),
	    NBPG - ALIGN(sizeof(struct wds_mbx))))
		panic("wds_init: can't create scbs");

	/*
	 * Create and load the mailbox DMA map.
	 */
	if (bus_dmamap_create(sc->sc_dmat, sizeof(struct wds_mbx), 1,
	    sizeof(struct wds_mbx), 0, BUS_DMA_NOWAIT, &sc->sc_dmamap_mbox) ||
	    bus_dmamap_load(sc->sc_dmat, sc->sc_dmamap_mbox, wmbx,
	    sizeof(struct wds_mbx), NULL, BUS_DMA_NOWAIT))
		panic("wds_ionit: can't craete or load mailbox dma map");

 doinit:
	/*
	 * Set up initial mail box for round-robin operation.
	 */
	for (i = 0; i < WDS_MBX_SIZE; i++) {
		wmbx->mbo[i].cmd = WDS_MBO_FREE;
		wmbx->mbi[i].stat = WDS_MBI_FREE;
	}
	wmbx->cmbo = wmbx->tmbo = &wmbx->mbo[0];
	wmbx->tmbi = &wmbx->mbi[0];
	sc->sc_mbofull = 0;

	init.opcode = WDSC_INIT;
	init.scsi_id = sc->sc_link.scsipi_scsi.adapter_target;
	init.buson_t = 48;
	init.busoff_t = 24;
	init.xx = 0;
	ltophys(sc->sc_dmamap_mbox->dm_segs[0].ds_addr, init.mbaddr);
	init.nomb = init.nimb = WDS_MBX_SIZE;
	wds_cmd(iot, ioh, (u_char *)&init, sizeof init);

	wds_wait(iot, ioh, WDS_STAT, WDSS_INIT, WDSS_INIT);

	c = WDSC_DISUNSOL;
	wds_cmd(iot, ioh, &c, sizeof c);
}

/*
 * Read the board's firmware revision information.
 */
void
wds_inquire_setup_information(sc)
	struct wds_softc *sc;
{
	bus_space_tag_t iot = sc->sc_iot;
	bus_space_handle_t ioh = sc->sc_ioh;
	struct wds_scb *scb;
	u_char *j;
	int s;

	sc->sc_maxsegs = 1;

	scb = wds_get_scb(sc, SCSI_NOSLEEP);
	if (scb == 0)
		panic("wds_inquire_setup_information: no scb available");

	scb->xs = NULL;
	scb->timeout = 40;

	bzero(&scb->cmd, sizeof scb->cmd);
	scb->cmd.write = 0x80;
	scb->cmd.opcode = WDSX_GETFIRMREV;

	/* Will poll card, await result. */
	bus_space_write_1(iot, ioh, WDS_HCR, WDSH_DRQEN);
	scb->flags |= SCB_POLLED;

	s = splbio();
	wds_queue_scb(sc, scb);
	splx(s);

	if (wds_ipoll(sc, scb, scb->timeout))
		goto out;

	/* Print the version number. */
	printf("%s: version %x.%02x ", sc->sc_dev.dv_xname,
	    scb->cmd.targ, scb->cmd.scb.opcode);
	sc->sc_revision = (scb->cmd.targ << 8) | scb->cmd.scb.opcode;
	/* Print out the version string. */
	j = 2 + &(scb->cmd.targ);
	while ((*j >= 32) && (*j < 128)) {
		printf("%c", *j);
		j++;
	}

	/*
	 * Determine if we can use scatter/gather.
	 */
	if (sc->sc_revision >= 0x800)
		sc->sc_maxsegs = WDS_NSEG;

out:
	printf("\n");

	/*
	 * Free up the resources used by this scb.
	 */
	wds_free_scb(sc, scb);
}

void
wdsminphys(bp)
	struct buf *bp;
{

	if (bp->b_bcount > WDS_MAXXFER)
		bp->b_bcount = WDS_MAXXFER;
	minphys(bp);
}

/*
 * Send a SCSI command.
 */
int
wds_scsi_cmd(xs)
	struct scsipi_xfer *xs;
{
	struct scsipi_link *sc_link = xs->sc_link;
	struct wds_softc *sc = sc_link->adapter_softc;
	bus_dma_tag_t dmat = sc->sc_dmat;
	struct wds_scb *scb;
	struct wds_scat_gath *sg;
	int error, seg, flags, s;
	int fromqueue = 0, dontqueue = 0;
#ifdef TFS
	struct iovec *iovp;
#endif

	if (xs->flags & SCSI_RESET) {
		/* XXX Fix me! */
		printf("%s: reset!\n", sc->sc_dev.dv_xname);
		wds_init(sc, 1);
		return COMPLETE;
	}

	s = splbio();		/* protect the queue */

	/*
	 * If we're running the queue from wds_done(), we've been
	 * called with the first queue entry as our argument.
	 */
	if (xs == sc->sc_queue.lh_first) {
		xs = wds_dequeue(sc);
		fromqueue = 1;
		goto get_scb;
	}

	/* Polled requests can't be queued for later. */
	dontqueue = xs->flags & SCSI_POLL;

	/*
	 * If there are jobs in the queue, run them first.
	 */
	if (sc->sc_queue.lh_first != NULL) {
		/*
		 * If we can't queue, we have to abort, since
		 * we have to preserve order.
		 */
		if (dontqueue) {
			splx(s);
			xs->error = XS_DRIVER_STUFFUP;
			return (TRY_AGAIN_LATER);
		}

		/*
		 * Swap with the first queue entry.
		 */
		wds_enqueue(sc, xs, 0);
		xs = wds_dequeue(sc);
		fromqueue = 1;
	}

 get_scb:
	flags = xs->flags;
	if ((scb = wds_get_scb(sc, flags)) == NULL) {
		/*
		 * If we can't queue, we lose.
		 */
		if (dontqueue) {
			splx(s);
			xs->error = XS_DRIVER_STUFFUP;
			return (TRY_AGAIN_LATER);
		}

		/*
		 * Stuff ourselves into the queue, in front
		 * if we came off in the first place.
		 */
		wds_enqueue(sc, xs, fromqueue);
		splx(s);
		return (SUCCESSFULLY_QUEUED);
	}

	splx(s);		/* done playing with the queue */

	scb->xs = xs;
	scb->timeout = xs->timeout;

	if (xs->flags & SCSI_DATA_UIO) {
		/* XXX Fix me! */
		/* Let's not worry about UIO. There isn't any code for the *
		 * non-SG boards anyway! */
		printf("%s: UIO is untested and disabled!\n",
		    sc->sc_dev.dv_xname);
		goto bad;
	}

	/* Zero out the command structure. */
	bzero(&scb->cmd, sizeof scb->cmd);
	bcopy(xs->cmd, &scb->cmd.scb, xs->cmdlen < 12 ? xs->cmdlen : 12);

	/* Set up some of the command fields. */
	scb->cmd.targ = (xs->sc_link->scsipi_scsi.target << 5) |
						xs->sc_link->scsipi_scsi.lun;

	/* NOTE: cmd.write may be OK as 0x40 (disable direction checking)
	 * on boards other than the WD-7000V-ASE. Need this for the ASE:
 	 */
	scb->cmd.write = (xs->flags & SCSI_DATA_IN) ? 0x80 : 0x00;

	if (xs->datalen) {
		sg = scb->scat_gath;
		seg = 0;
#ifdef TFS
		if (flags & SCSI_DATA_UIO) {
			error = bus_Dmamap_load_uio(dmat,
			    scb->dmamap_xfer, (struct uio *)xs->data,
			    (flags & SCSI_NOSLEEP) ? BUS_DMA_NOWAIT :
			    BUS_DMA_WAITOK);
		} else
#endif /* TFS */
		{
			error = bus_dmamap_load(dmat,
			    scb->dmamap_xfer, xs->data, xs->datalen, NULL,
			    (flags & SCSI_NOSLEEP) ? BUS_DMA_NOWAIT :
			    BUS_DMA_WAITOK);
		}

		if (error) {
			if (error == EFBIG) {
				printf("%s: wds_scsi_cmd, more than %d"
				    " dma segments\n",
				    sc->sc_dev.dv_xname, sc->sc_maxsegs);
			} else {
				printf("%s: wds_scsi_cmd, error %d loading"
				    " dma map\n",
				    sc->sc_dev.dv_xname, error);
			}
			goto bad;
		}

		bus_dmamap_sync(dmat, scb->dmamap_xfer,
		    (flags & SCSI_DATA_IN) ? BUS_DMASYNC_PREREAD :
		    BUS_DMASYNC_PREWRITE);

		if (sc->sc_maxsegs > 1) {
			/*
			 * Load the hardware scatter/gather map with the
			 * contents of the DMA map.
			 */
			for (seg = 0; seg < scb->dmamap_xfer->dm_nsegs;
			    seg++) {
				ltophys(scb->dmamap_xfer->dm_segs[seg].ds_addr,
				    scb->scat_gath[seg].seg_addr);
				ltophys(scb->dmamap_xfer->dm_segs[seg].ds_len,
				    scb->scat_gath[seg].seg_len);
			}

			/*
			 * Set up for scatter/gather transfer.
			 */
			scb->cmd.opcode = WDSX_SCSISG;
			ltophys(scb->dmamap_self->dm_segs[0].ds_addr +
			    offsetof(struct wds_scb, scat_gath),
			    scb->cmd.data);
			ltophys(scb->dmamap_self->dm_nsegs *
			    sizeof(struct wds_scat_gath), scb->cmd.len);
		} else {
			/*
			 * This board is an ASC or an ASE, and the
			 * transfer has been mapped contig for us.
			 */
			scb->cmd.opcode = WDSX_SCSICMD;
			ltophys(scb->dmamap_xfer->dm_segs[0].ds_addr,
			    scb->cmd.data);
			ltophys(scb->dmamap_xfer->dm_segs[0].ds_len,
			    scb->cmd.len);
		}
	} else {
		scb->cmd.opcode = WDSX_SCSICMD;
		ltophys(0, scb->cmd.data);
		ltophys(0, scb->cmd.len);
	}

	scb->cmd.stat = 0x00;
	scb->cmd.venderr = 0x00;
	ltophys(0, scb->cmd.link);

	/* XXX Do we really want to do this? */
	if (flags & SCSI_POLL) {
		/* Will poll card, await result. */
		bus_space_write_1(sc->sc_iot, sc->sc_ioh, WDS_HCR, WDSH_DRQEN);
		scb->flags |= SCB_POLLED;
	} else {
		/* Will send command, let interrupt routine handle result. */
		bus_space_write_1(sc->sc_iot, sc->sc_ioh, WDS_HCR,
		    WDSH_IRQEN | WDSH_DRQEN);
	}

	s = splbio();
	wds_queue_scb(sc, scb);
	splx(s);

	if ((flags & SCSI_POLL) == 0)
		return SUCCESSFULLY_QUEUED;

	if (wds_poll(sc, xs, scb->timeout)) {
		wds_timeout(scb);
		if (wds_poll(sc, xs, scb->timeout))
			wds_timeout(scb);
	}
	return COMPLETE;

bad:
	xs->error = XS_DRIVER_STUFFUP;
	wds_free_scb(sc, scb);
	return COMPLETE;
}

/*
 * Send a sense request.
 */
void
wds_sense(sc, scb)
	struct wds_softc *sc;
	struct wds_scb *scb;
{
	struct scsipi_xfer *xs = scb->xs;
	struct scsipi_sense *ss = (void *)&scb->sense.scb;
	int s;

	/* XXXXX */

	/* Send sense request SCSI command. */
	xs->error = XS_SENSE;
	scb->flags |= SCB_SENSE;

	/* Next, setup a request sense command block */
	bzero(ss, sizeof(*ss));
	ss->opcode = REQUEST_SENSE;
	ss->byte2 = xs->sc_link->scsipi_scsi.lun << 5;
	ss->length = sizeof(struct scsipi_sense_data);

	/* Set up some of the command fields. */
	scb->sense.targ = scb->cmd.targ;
	scb->sense.write = 0x80;
	scb->sense.opcode = WDSX_SCSICMD;
	ltophys(scb->dmamap_self->dm_segs[0].ds_addr +
	    offsetof(struct wds_scb, sense_data), scb->sense.data);
	ltophys(sizeof(struct scsipi_sense_data), scb->sense.len);

	s = splbio();
	wds_queue_scb(sc, scb);
	splx(s);

	/*
	 * There's no reason for us to poll here.  There are two cases:
	 * 1) If it's a polling operation, then we're called from the interrupt
	 *    handler, and we return and continue polling.
	 * 2) If it's an interrupt-driven operation, then it gets completed
	 *    later on when the REQUEST SENSE finishes.
	 */
}

/*
 * Poll a particular unit, looking for a particular scb
 */
int
wds_poll(sc, xs, count)
	struct wds_softc *sc;
	struct scsipi_xfer *xs;
	int count;
{
	bus_space_tag_t iot = sc->sc_iot;
	bus_space_handle_t ioh = sc->sc_ioh;

	/* timeouts are in msec, so we loop in 1000 usec cycles */
	while (count) {
		/*
		 * If we had interrupts enabled, would we
		 * have got an interrupt?
		 */
		if (bus_space_read_1(iot, ioh, WDS_STAT) & WDSS_IRQ)
			wdsintr(sc);
		if (xs->flags & ITSDONE)
			return 0;
		delay(1000);	/* only happens in boot so ok */
		count--;
	}
	return 1;
}

/*
 * Poll a particular unit, looking for a particular scb
 */
int
wds_ipoll(sc, scb, count)
	struct wds_softc *sc;
	struct wds_scb *scb;
	int count;
{
	bus_space_tag_t iot = sc->sc_iot;
	bus_space_handle_t ioh = sc->sc_ioh;

	/* timeouts are in msec, so we loop in 1000 usec cycles */
	while (count) {
		/*
		 * If we had interrupts enabled, would we
		 * have got an interrupt?
		 */
		if (bus_space_read_1(iot, ioh, WDS_STAT) & WDSS_IRQ)
			wdsintr(sc);
		if (scb->flags & SCB_DONE)
			return 0;
		delay(1000);	/* only happens in boot so ok */
		count--;
	}
	return 1;
}

void
wds_timeout(arg)
	void *arg;
{
	struct wds_scb *scb = arg;
	struct scsipi_xfer *xs = scb->xs;
	struct scsipi_link *sc_link = xs->sc_link;
	struct wds_softc *sc = sc_link->adapter_softc;
	int s;

	scsi_print_addr(sc_link);
	printf("timed out");

	s = splbio();

#ifdef WDSDIAG
	/*
	 * If The scb's mbx is not free, then the board has gone south?
	 */
	wds_collect_mbo(sc);
	if (scb->flags & SCB_SENDING) {
		printf("%s: not taking commands!\n", sc->sc_dev.dv_xname);
		Debugger();
	}
#endif

	/*
	 * If it has been through before, then
	 * a previous abort has failed, don't
	 * try abort again
	 */
	if (scb->flags & SCB_ABORT) {
		/* abort timed out */
		printf(" AGAIN\n");
		/* XXX Must reset! */
	} else {
		/* abort the operation that has timed out */
		printf("\n");
		scb->xs->error = XS_TIMEOUT;
		scb->timeout = WDS_ABORT_TIMEOUT;
		scb->flags |= SCB_ABORT;
		wds_queue_scb(sc, scb);
	}

	splx(s);
}