freebsd-nq/sys/scsi/od.c

/*
 * Copyright (c) 1995,1996 Shunsuke Akiyama.  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 Shunsuke Akiyama.
 * 4. Neither the name of the author nor the names of any co-contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY Shunsuke Akiyama 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 Shunsuke Akiyama 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.
 *
 *	$Id: od.c,v 1.24 1996/12/01 11:25:17 sos Exp $
 */

/*
 * Compile option defines:
 */

/*
 * If drive returns sense key as 0x02 with vendor specific additional
 * sense code (ASC) and additional sense code qualifier (ASCQ), or
 * illegal ASC and ASCQ. This cause an error (NOT READY) and retrying.
 * To suppress this, uncomment following.
 * Or put "options OD_BOGUS_NOT_READY" entry into your kernel
 * configuration file.
 *
#define OD_BOGUS_NOT_READY
 */

/*
 * For an automatic spindown, try this.  Again, preferrably as an
 * option in your config file.
 * WARNING!  Use at your own risk.  Joerg's ancient SONY SMO drive
 * groks it fine, while Shunsuke's Fujitsu chokes on it and times
 * out.
#define OD_AUTO_TURNOFF
 */

#include "opt_bounce.h"
#include "opt_scsi.h"
#include "opt_od.h"

#define SPLOD splbio
#include <sys/types.h>
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/dkbad.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/buf.h>
#include <sys/uio.h>
#include <sys/malloc.h>
#include <sys/cdio.h>
#include <sys/errno.h>
#include <sys/dkstat.h>
#include <sys/disklabel.h>
#include <sys/diskslice.h>
#ifdef DEVFS
#include <sys/devfsext.h>
#endif /*DEVFS*/
#include <scsi/scsi_all.h>
#include <scsi/scsi_disk.h>
#include <scsi/scsiconf.h>
#include <vm/vm.h>
#include <sys/dkstat.h>
#include <machine/md_var.h>

static u_int32_t odstrats, odqueues;

#define SECSIZE		512	/* default sector size */
#define	ODOUTSTANDING	4
#define	OD_RETRIES	4

#define	PARTITION(dev)	dkpart(dev)
#define	ODUNIT(dev)	dkunit(dev)

/* XXX introduce a dkmodunit() macro for this. */
#define ODSETUNIT(DEV, U) \
 makedev(major(DEV), dkmakeminor((U), dkslice(DEV), dkpart(DEV)))

struct scsi_data {
	u_int32_t flags;
#define	ODINIT		0x04	/* device has been init'd */
	struct disk_parms {
		u_char    heads;	/* Number of heads */
		u_int16_t cyls;		/* Number of cylinders (ficticous) */
		u_int16_t sectors;	/* Number of sectors/track */
		u_int16_t secsiz;	/* Number of bytes/sector */
		u_int32_t disksize;	/* total number sectors */
		u_int16_t rpm;		/* medium rotation rate */
	} params;
	struct diskslices *dk_slices;	/* virtual drives */
	struct buf_queue_head buf_queue;
	int dkunit;		/* disk stats unit number */
#ifdef DEVFS
	/* Eventually move all these to common disk struct. */
	void	*b_devfs_token;
	void	*c_devfs_token;
	void	*ctl_devfs_token;
#endif
};

static errval	od_get_parms __P((int unit, int flags));
#ifdef notyet
static errval	od_reassign_blocks __P((int unit, int block));
#endif
static u_int32_t	od_size __P((int unit, int flags));
static int	od_sense_handler __P((struct scsi_xfer *));
static void	odstart __P((u_int32_t, u_int32_t));
static void	odstrategy1 __P((struct buf *));

static dev_t odsetunit(dev_t dev, int unit) { return ODSETUNIT(dev, unit); }
static int odunit(dev_t dev) { return ODUNIT(dev); }

static errval od_open __P((dev_t dev, int mode, int fmt, struct proc *p,
			   struct scsi_link *sc_link));
static errval od_ioctl(dev_t dev, int cmd, caddr_t addr, int flag,
		       struct proc *p, struct scsi_link *sc_link);
static errval od_close __P((dev_t dev, int fflag, int fmt, struct proc *p,
			    struct scsi_link *sc_link));
static void od_strategy(struct buf *bp, struct scsi_link *sc_link);

static	d_open_t	odopen;
static	d_close_t	odclose;
static	d_ioctl_t	odioctl;
static	d_strategy_t	odstrategy;

#define CDEV_MAJOR 70
#define BDEV_MAJOR 20
static struct cdevsw od_cdevsw;
static struct bdevsw od_bdevsw = 
	{ odopen,	odclose,	odstrategy,	odioctl,	/*20*/
	  nodump,	nopsize,	0,	"od",	&od_cdevsw,	-1 };


/*
 * Actually include the interface routines
 */
SCSI_DEVICE_ENTRIES(od)

static struct scsi_device od_switch =
{
	od_sense_handler,
	odstart,		/* have a queue, served by this */
	NULL,			/* have no async handler */
	NULL,			/* Use default 'done' routine */
	"od",
	0,
	{0, 0},
	0,			/* Link flags */
	odattach,
	"Optical",
	odopen,
	sizeof(struct scsi_data),
	T_OPTICAL,
	odunit,
	odsetunit,
	od_open,
	od_ioctl,
	od_close,
	od_strategy,
};

static inline void
od_registerdev(int unit)
{
	if(dk_ndrive < DK_NDRIVE) {
		sprintf(dk_names[dk_ndrive], "od%d", unit);
		dk_wpms[dk_ndrive] = (4*1024*1024/2);	/* 4MB/sec */
		SCSI_DATA(&od_switch, unit)->dkunit = dk_ndrive++;
	} else {
		SCSI_DATA(&od_switch, unit)->dkunit = -1;
	}
}


/*
 * The routine called by the low level scsi routine when it discovers
 * a device suitable for this driver.
 */
static errval
odattach(struct scsi_link *sc_link)
{
	u_int32_t unit;
	struct disk_parms *dp;
#ifdef DEVFS
	int	mynor;
#endif

	struct scsi_data *od = sc_link->sd;

	unit = sc_link->dev_unit;

	dp = &(od->params);

	if (sc_link->opennings > ODOUTSTANDING)
		sc_link->opennings = ODOUTSTANDING;

	TAILQ_INIT(&od->buf_queue);
	/*
	 * Use the subdriver to request information regarding
	 * the drive. We cannot use interrupts yet, so the
	 * request must specify this.
	 */
	scsi_start_unit(sc_link, SCSI_NOSLEEP | SCSI_NOMASK
				 | SCSI_ERR_OK | SCSI_SILENT);
	od_get_parms(unit, SCSI_NOSLEEP | SCSI_NOMASK | SCSI_SILENT);
	/*
	 * if we don't have actual parameters, assume 512 bytes/sec
	 * (could happen on removable media - MOD)
	 * -- this avoids the division below from falling over
	 */
	if(dp->secsiz == 0) dp->secsiz = SECSIZE;
	if (dp->disksize != 0) {
		printf("%ldMB (%ld %d byte sectors)",
		    dp->disksize / ((1024L * 1024L) / dp->secsiz),
		    dp->disksize,
		    dp->secsiz);
	} else {
		printf("od not present");
	}

#ifndef SCSI_REPORT_GEOMETRY
	if ( (sc_link->flags & SDEV_BOOTVERBOSE) )
#endif
	{
		sc_print_addr(sc_link);
		printf("with approximate %d cyls, %d heads, and %d sectors/track",
	   	dp->cyls, dp->heads, dp->sectors);
	}
#ifdef OD_AUTO_TURNOFF
	scsi_stop_unit(sc_link, 0, SCSI_ERR_OK | SCSI_SILENT);
#endif /* OD_AUTO_TURNOFF */

	od->flags |= ODINIT;
	od_registerdev(unit);

#ifdef DEVFS
	mynor = dkmakeminor(unit, WHOLE_DISK_SLICE, RAW_PART);
	od->b_devfs_token = devfs_add_devswf(&od_bdevsw, mynor, DV_BLK,
					     UID_ROOT, GID_OPERATOR, 0640,
					     "od%d", unit);
	od->c_devfs_token = devfs_add_devswf(&od_cdevsw, mynor, DV_CHR,
					     UID_ROOT, GID_OPERATOR, 0640,
					     "rod%d", unit);
	mynor = dkmakeminor(unit, 0, 0);	/* XXX */
	od->ctl_devfs_token = devfs_add_devswf(&od_cdevsw,
					       mynor | SCSI_CONTROL_MASK,
					       DV_CHR,
					       UID_ROOT, GID_WHEEL, 0600,
					       "rod%d.ctl", unit);
#endif

	return 0;
}

/*
 * open the device. Make sure the partition info is a up-to-date as can be.
 */
static errval
od_open(dev, mode, fmt, p, sc_link)
	dev_t	dev;
	int	mode;
	int	fmt;
	struct proc *p;
	struct scsi_link *sc_link;
{
	errval  errcode = 0;
	u_int32_t unit;
	struct disklabel label;
	struct scsi_data *od;

	unit = ODUNIT(dev);
	od = sc_link->sd;

	/*
	 * Make sure the disk has been initialized
	 * At some point in the future, get the scsi driver
	 * to look for a new device if we are not initted
	 */
	if ((!od) || (!(od->flags & ODINIT))) {
		return ENXIO;
	}

	SC_DEBUG(sc_link, SDEV_DB1,
	    ("od_open: dev=0x%lx (unit %ld, partition %d)\n",
		dev, unit, PARTITION(dev)));

	/*
	 * Try to start the drive, and try to clear "Unit Attention"
	 * condition, when media had been changed before.
	 * This operation also clears the SDEV_MEDIA_LOADED flag in its
	 * error handling routine.
	 */
	scsi_start_unit(sc_link, SCSI_SILENT);
	scsi_prevent(sc_link, PR_PREVENT, SCSI_ERR_OK | SCSI_SILENT);

	/*
	 * Make sure the drive is ready.
	 */
	scsi_test_unit_ready(sc_link, 0);

	SC_DEBUG(sc_link, SDEV_DB3, ("'start' attempted "));

	sc_link->flags |= SDEV_OPEN;	/* unit attn becomes an err now */
	/*
	 * If it's been invalidated, then forget the label.
	 */
	if (!(sc_link->flags & SDEV_MEDIA_LOADED)) {
		/*
		 * If somebody still has it open, then forbid re-entry.
		 */
		if (dsisopen(od->dk_slices)) {
			errcode = ENXIO;
			goto bad;
		}

		if (od->dk_slices != NULL)
			dsgone(&od->dk_slices);
	}

	/*
	 * This time actually take notice of error returns
	 */
	if (scsi_test_unit_ready(sc_link, SCSI_SILENT) != 0) {
		SC_DEBUG(sc_link, SDEV_DB3, ("not ready\n"));
		errcode = ENXIO;
		goto bad;
	}
	SC_DEBUG(sc_link, SDEV_DB3, ("device present\n"));

	/*
	 * Load the physical device parameters
	 */
	errcode = od_get_parms(unit, 0);	/* sets SDEV_MEDIA_LOADED */
	if (errcode) {
		goto bad;
	}
	switch (od->params.secsiz) {
	case SECSIZE :
	case 1024 :
	case 2048 :
		break;
	default :
		printf("od%ld: Can't deal with %d bytes logical blocks\n",
		    unit, od->params.secsiz);
		Debugger("od");
		errcode = ENXIO;
		goto bad;
	}
	SC_DEBUG(sc_link, SDEV_DB3, ("params loaded "));

	/* Build label for whole disk. */
	bzero(&label, sizeof label);
	label.d_secsize = od->params.secsiz;
	label.d_nsectors = od->params.sectors;
	label.d_ntracks = od->params.heads;
	label.d_ncylinders = od->params.cyls;
	label.d_secpercyl = od->params.heads * od->params.sectors;
	label.d_rpm = od->params.rpm;	/* maybe wrong */
	if (label.d_secpercyl == 0)
		label.d_secpercyl = 64*32;
		/* XXX as long as it's not 0
		 *  - readdisklabel divides by it (?)
		 */
	label.d_secperunit = od->params.disksize;

	/* Initialize slice tables. */
	errcode = dsopen("od", dev, fmt, &od->dk_slices, &label, odstrategy1,
			 (ds_setgeom_t *)NULL, &od_bdevsw, &od_cdevsw);
	if (errcode != 0)
		goto bad;
	SC_DEBUG(sc_link, SDEV_DB3, ("Slice tables initialized "));

	SC_DEBUG(sc_link, SDEV_DB3, ("open %ld %ld\n", odstrats, odqueues));

	return 0;

bad:
	if (!dsisopen(od->dk_slices)) {
		scsi_prevent(sc_link, PR_ALLOW, SCSI_ERR_OK | SCSI_SILENT);
#ifdef OD_AUTO_TURNOFF
		scsi_stop_unit(sc_link, 0, SCSI_ERR_OK | SCSI_SILENT);
#endif /* OD_AUTO_TURNOFF */
		sc_link->flags &= ~SDEV_OPEN;
	}
	return errcode;
}

/*
 * close the device.. only called if we are the LAST occurence of an open
 * device.  Convenient now but usually a pain.
 */
static errval
od_close(dev, fflag, fmt, p, sc_link)
	dev_t	dev;
	int	fflag;
	int	fmt;
	struct proc *p;
	struct scsi_link *sc_link;
{
	struct scsi_data *od;

	od = sc_link->sd;
	dsclose(dev, fmt, od->dk_slices);
	if (!dsisopen(od->dk_slices)) {
		scsi_prevent(sc_link, PR_ALLOW, SCSI_SILENT | SCSI_ERR_OK);
#ifdef OD_AUTO_TURNOFF
		scsi_stop_unit(sc_link, 0, SCSI_ERR_OK | SCSI_SILENT);
#endif /* OD_AUTO_TURNOFF */
		sc_link->flags &= ~SDEV_OPEN;
	}
	return 0;
}

/*
 * Actually translate the requested transfer into one the physical driver
 * can understand.  The transfer is described by a buf and will include
 * only one physical transfer.
 */
static void
od_strategy(struct buf *bp, struct scsi_link *sc_link)
{
	u_int32_t opri;
	struct scsi_data *od;
	u_int32_t unit;
	int secsize;

	odstrats++;
	unit = ODUNIT((bp->b_dev));
	od = sc_link->sd;

	/*
	 * If the device has been made invalid, error out
	 */
	if (!(sc_link->flags & SDEV_MEDIA_LOADED)) {
		bp->b_error = EIO;
		goto bad;
	}

	/*
	 * Odd number of bytes or negative offset
	 */
	if (bp->b_blkno < 0 ) {
		bp->b_error = EINVAL;
		printf("od_strategy: Negative block number: 0x%x\n", bp->b_blkno);
		goto bad;
	}

	
	secsize = od->params.secsiz;

	/* make sure the blkno is scalable */
	if( (bp->b_blkno % (secsize/DEV_BSIZE)) != 0 ) {
		bp->b_error = EINVAL;
		printf("od_strategy: Block number is not multiple of sector size (2): 0x%x\n", bp->b_blkno);
		goto bad;
	}

	/* make sure that the transfer size is a multiple of the sector size */
	if( (bp->b_bcount % secsize) != 0 ) {
		bp->b_error = EINVAL;
		printf("od_strategy: Invalid b_bcount %d at block number: 0x%x\n", bp->b_bcount, bp->b_blkno);
		goto bad;
	}

	/*
	 * Do bounds checking, adjust transfer, and set b_pblkno.
	 */
	{
	int status;
	int sec_blk_ratio = secsize/DEV_BSIZE;
	/* save original block number and size */
	int b_blkno = bp->b_blkno;
	int b_bcount = bp->b_bcount;

	/* replace with scaled values */
	bp->b_blkno /= sec_blk_ratio;
	bp->b_bcount /= sec_blk_ratio;
	
	/* have dscheck enforce limits and map to physical block number */
	status = dscheck(bp, od->dk_slices);

	/* restore original values to prevent bad side effects in block system */
	bp->b_blkno = b_blkno;
	bp->b_bcount = b_bcount;
	/* scale resid */
	bp->b_resid *= sec_blk_ratio;

	/* see if the mapping failed */
	if (status <= 0)
		{
		goto done;	/* XXX check b_resid */
		}
	}

	opri = SPLOD();

	/*
	 * Use a bounce buffer if necessary
	 */
#ifdef BOUNCE_BUFFERS
	if (sc_link->flags & SDEV_BOUNCE)
		vm_bounce_alloc(bp);
#endif

	/*
	 * Place it in the queue of disk activities for this disk
	 */
	TAILQ_INSERT_TAIL(&od->buf_queue, bp, b_act);

	/*
	 * Tell the device to get going on the transfer if it's
	 * not doing anything, otherwise just wait for completion
	 */
	odstart(unit, 0);

	splx(opri);
	return /*0*/;
bad:
	bp->b_flags |= B_ERROR;
done:

	/*
	 * Correctly set the buf to indicate a completed xfer
	 */
	bp->b_resid = bp->b_bcount;
	biodone(bp);
	return /*0*/;
}

static void
odstrategy1(struct buf *bp)
{
	/*
	 * XXX - do something to make odstrategy() but not this block while
	 * we're doing dsinit() and dsioctl().
	 */
	odstrategy(bp);
}

/*
 * odstart looks to see if there is a buf waiting for the device
 * and that the device is not already busy. If both are true,
 * It dequeues the buf and creates a scsi command to perform the
 * transfer in the buf. The transfer request will call scsi_done
 * on completion, which will in turn call this routine again
 * so that the next queued transfer is performed.
 * The bufs are queued by the strategy routine (odstrategy)
 *
 * This routine is also called after other non-queued requests
 * have been made of the scsi driver, to ensure that the queue
 * continues to be drained.
 *
 * must be called at the correct (highish) spl level
 * odstart() is called at SPLOD  from odstrategy and scsi_done
 */
static void
odstart(u_int32_t unit, u_int32_t flags)
{
	register struct	scsi_link *sc_link = SCSI_LINK(&od_switch, unit);
	register struct scsi_data *od = sc_link->sd;
	struct buf *bp = 0;
	struct scsi_rw_big cmd;
	u_int32_t blkno, nblk;
	u_int32_t secsize;

	SC_DEBUG(sc_link, SDEV_DB2, ("odstart "));
	/*
	 * Check if the device has room for another command
	 */
	while (sc_link->opennings) {

		/*
		 * there is excess capacity, but a special waits
		 * It'll need the adapter as soon as we clear out of the
		 * way and let it run (user level wait).
		 */
		if (sc_link->flags & SDEV_WAITING) {
			return;
		}
		/*
		 * See if there is a buf with work for us to do..
		 */
		bp = od->buf_queue.tqh_first;
		if (bp == NULL) {	/* yes, an assign */
			return;
		}
		TAILQ_REMOVE( &od->buf_queue, bp, b_act);

		/*
		 *  If the device has become invalid, abort all the
		 * reads and writes until all files have been closed and
		 * re-openned
		 */
		if (!(sc_link->flags & SDEV_MEDIA_LOADED)) {
			goto bad;
		}
		/*
		 * We have a buf, now we know we are going to go through
		 * With this thing..
		 */
		secsize = od->params.secsiz;
		blkno = bp->b_pblkno;
		if (bp->b_bcount & (secsize - 1))
		{
		    goto bad;
		}
		nblk = bp->b_bcount / secsize;

		/*
		 *  Fill out the scsi command
		 */
		cmd.op_code = (bp->b_flags & B_READ)
		    ? READ_BIG : WRITE_BIG;
		scsi_uto4b(blkno, &cmd.addr_3);
		scsi_uto2b(nblk, &cmd.length2);
		cmd.byte2 = cmd.reserved = cmd.control = 0;
		/*
		 * Call the routine that chats with the adapter.
		 * Note: we cannot sleep as we may be an interrupt
		 */
		if (scsi_scsi_cmd(sc_link,
			(struct scsi_generic *) &cmd,
			sizeof(cmd),
			(u_char *) bp->b_un.b_addr,
			bp->b_bcount,
			OD_RETRIES,
			100000,
			bp,
			flags | ((bp->b_flags & B_READ) ?
			    SCSI_DATA_IN : SCSI_DATA_OUT))
		    == SUCCESSFULLY_QUEUED) {
			odqueues++;
			if(od->dkunit >= 0) {
				dk_xfer[od->dkunit]++;
				dk_seek[od->dkunit]++; /* don't know */
				dk_wds[od->dkunit] += bp->b_bcount >> 6;
			}
		} else {
bad:
			printf("od%ld: oops not queued\n", unit);
			bp->b_error = EIO;
			bp->b_flags |= B_ERROR;
			biodone(bp);
		}
	}
}

/*
 * Perform special action on behalf of the user
 * Knows about the internals of this device
 */
static errval
od_ioctl(dev_t dev, int cmd, caddr_t addr, int flag, struct proc *p,
	 struct scsi_link *sc_link)
{
	/* struct od_cmd_buf *args; */
	errval  error;
	struct scsi_data *od;

	/*
	 * Find the device that the user is talking about
	 */
	od = sc_link->sd;
	SC_DEBUG(sc_link, SDEV_DB1, ("odioctl (0x%x)", cmd));

	/*
	 * If the device is not valid.. abandon ship
	 */
	if (!(sc_link->flags & SDEV_MEDIA_LOADED))
		return EIO;

	switch (cmd) {
	case DIOCSBAD:
		error = EINVAL;
		break;
	case CDIOCEJECT:
		error = scsi_stop_unit(sc_link, 1, 0);
		sc_link->flags &= ~SDEV_MEDIA_LOADED;
		break;
	case CDIOCALLOW:
		error = scsi_prevent(sc_link, PR_ALLOW, 0);
		break;
	case CDIOCPREVENT:
		error = scsi_prevent(sc_link, PR_PREVENT, 0);
		break;
	default:
		error = dsioctl("od", dev, cmd, addr, flag, &od->dk_slices,
				odstrategy1, (ds_setgeom_t *)NULL);
		if (error == -1) {
			if (PARTITION(dev) != RAW_PART) {
				error = ENOTTY;
			} else {
				error = scsi_do_ioctl(dev, cmd, addr,
						      flag, p, sc_link);
			}
		}
		break;
	}
	return error;
}

/*
 * Find out from the device what it's capacity is
 */
static u_int32_t
od_size(unit, flags)
	int	unit, flags;
{
	struct scsi_read_cap_data rdcap;
	struct scsi_read_capacity rdcap_cmd;
	struct scsi_link *sc_link = SCSI_LINK(&od_switch, unit);
	struct scsi_data *od = sc_link->sd;
	struct scsi_mode_sense mdsense_cmd;
	struct scsi_mode_sense_data {
		struct scsi_mode_header header;
		struct blk_desc blk_desc;
		union disk_pages pages;
	} scsi_sense;

	/*
	 * make up a scsi command and ask the scsi driver to do
	 * it for you.
	 */
	bzero(&rdcap_cmd, sizeof(rdcap_cmd));
	rdcap_cmd.op_code = READ_CAPACITY;

	/*
	 * If the command works, interpret the result as a 4 byte
	 * number of blocks
	 */
	if (scsi_scsi_cmd(sc_link,
		(struct scsi_generic *) &rdcap_cmd,
		sizeof(rdcap_cmd),
		(u_char *) & rdcap,
		sizeof(rdcap),
		OD_RETRIES,
		10000,
		NULL,
		flags | SCSI_DATA_IN) != 0) {
		return 0;
	} else {
		od->params.disksize = scsi_4btou(&rdcap.addr_3) + 1;
		od->params.secsiz = scsi_4btou(&rdcap.length_3);
	}

	/*
	 * do a "mode sense page 4" (rigid disk drive geometry)
	 */
	bzero(&mdsense_cmd, sizeof(mdsense_cmd));
	mdsense_cmd.op_code = MODE_SENSE;
	mdsense_cmd.page = 4;
	mdsense_cmd.length = 0x20;
	/*
	 * If the command worked, use the results to fill out
	 * the parameter structure
	 */
	if (scsi_scsi_cmd(sc_link,
		(struct scsi_generic *) &mdsense_cmd,
		sizeof(mdsense_cmd),
		(u_char *) & scsi_sense,
		sizeof(scsi_sense),
		OD_RETRIES,
		10000,
		NULL,
		flags | SCSI_SILENT | SCSI_DATA_IN) != 0) {

		/* default to a ficticous geometry */
		od->params.heads = 64;
	} else {
		SC_DEBUG(sc_link, SDEV_DB3,
			 ("%ld cyls, %d heads, %d rpm\n",
			scsi_3btou(&scsi_sense.pages.rigid_geometry.ncyl_2),
			scsi_sense.pages.rigid_geometry.nheads,
			scsi_2btou(&scsi_sense.pages.rigid_geometry.medium_rot_rate_1)));

		od->params.heads = scsi_sense.pages.rigid_geometry.nheads;
		if (od->params.heads == 0)
			od->params.heads = 64; /* ficticous */
		od->params.rpm =
			scsi_2btou(&scsi_sense.pages.rigid_geometry.medium_rot_rate_1);
	}

	/*
	 * do a "mode sense page 3" (format device)
	 */
	bzero(&mdsense_cmd, sizeof(mdsense_cmd));
	mdsense_cmd.op_code = MODE_SENSE;
	mdsense_cmd.page = 3;
	mdsense_cmd.length = 0x20;
	/*
	 * If the command worked, use the results to fill out
	 * the parameter structure
	 */
	if (scsi_scsi_cmd(sc_link,
		(struct scsi_generic *) &mdsense_cmd,
		sizeof(mdsense_cmd),
		(u_char *) & scsi_sense,
		sizeof(scsi_sense),
		OD_RETRIES,
		10000,
		NULL,
		flags | SCSI_SILENT | SCSI_DATA_IN) != 0) {

		/* default to a ficticous geometry */
		od->params.sectors = 32;
	} else {
		SC_DEBUG(sc_link, SDEV_DB3,
			 ("%d secs\n",
			scsi_2btou(&scsi_sense.pages.disk_format.ph_sec_t_1)));

		od->params.sectors =
			scsi_2btou(&scsi_sense.pages.disk_format.ph_sec_t_1);
		if (od->params.sectors == 0)
			od->params.sectors = 32; /* ficticous */
	}

	return od->params.disksize;
}

#ifdef notyet
/*
 * Tell the device to map out a defective block
 */
static errval
od_reassign_blocks(unit, block)
	int	unit, block;
{
	struct scsi_reassign_blocks scsi_cmd;
	struct scsi_reassign_blocks_data rbdata;
	struct scsi_link *sc_link = SCSI_LINK(&od_switch, unit);

	bzero(&scsi_cmd, sizeof(scsi_cmd));
	bzero(&rbdata, sizeof(rbdata));
	scsi_cmd.op_code = REASSIGN_BLOCKS;

	rbdata.length_msb = 0;
	rbdata.length_lsb = sizeof(rbdata.defect_descriptor[0]);
	scsi_uto4b(block, &rbdata.defect_descriptor[0].dlbaddr_3);

	return scsi_scsi_cmd(sc_link,
		(struct scsi_generic *) &scsi_cmd,
		sizeof(scsi_cmd),
		(u_char *) & rbdata,
		sizeof(rbdata),
		OD_RETRIES,
		20000,
		NULL,
		SCSI_DATA_OUT);
}
#endif

/*
 * Get the scsi driver to send a full inquiry to the
 * device and use the results to fill out the disk
 * parameter structure.
 */
static errval
od_get_parms(unit, flags)
	int	unit, flags;
{
	struct scsi_link *sc_link = SCSI_LINK(&od_switch, unit);
	struct scsi_data *od = sc_link->sd;
	struct disk_parms *disk_parms = &od->params;
	u_int32_t sectors;
	errval retval;

	/*
	 * First check if we have it all loaded
	 */
	if (sc_link->flags & SDEV_MEDIA_LOADED)
		return 0;

	/*
	 * Use ficticious geometry, this depends on the size of medium.
	 */
	sectors = od_size(unit, flags);
	/* od_size() sets secsiz, disksize, sectors, and heads */

	/* ficticous number of cylinders, so that C*H*S <= total */
	if (disk_parms->sectors != 0 && disk_parms->heads != 0) {
		disk_parms->cyls =
		  sectors / (disk_parms->sectors * disk_parms->heads);
	} else {
		disk_parms->cyls = 0;
	}

	if (sectors != 0) {
		sc_link->flags |= SDEV_MEDIA_LOADED;
		retval = 0;
	} else {
		retval = ENXIO;
	}
	return retval;
}

/*
 * sense handler: Called to determine what to do when the
 * device returns a CHECK CONDITION.
 */

static int
od_sense_handler(struct scsi_xfer *xs)
{
	struct scsi_sense_data *sense;
	struct scsi_sense_extended *ext;
	int asc, ascq;

	sense = &(xs->sense);
	ext = (struct scsi_sense_extended *)&(sense->ext.extended);

	/* I don't know what the heck to do with a deferred error,
	 * so I'll just kick it back to the caller.
	 */
	if ((sense->error_code & SSD_ERRCODE) == 0x71)
		return SCSIRET_CONTINUE;

#ifdef OD_BOGUS_NOT_READY
	if (((sense->error_code & SSD_ERRCODE) == 0x70) &&
		((sense->ext.extended.flags & SSD_KEY) == 0x02))
		/* No point in retrying Not Ready */
			return SCSIRET_CONTINUE;
#endif

	if (((sense->error_code & SSD_ERRCODE) == 0x70) &&
		((sense->ext.extended.flags & SSD_KEY) == 0x04))
		/* No point in retrying Hardware Failure */
			return SCSIRET_CONTINUE;

	if (((sense->error_code & SSD_ERRCODE) == 0x70) &&
		((sense->ext.extended.flags & SSD_KEY) == 0x05))
		/* No point in retrying Illegal Requests */
			return SCSIRET_CONTINUE;

	asc = (ext->extra_len >= 5) ? ext->add_sense_code : 0;
	ascq = (ext->extra_len >= 6) ? ext->add_sense_code_qual : 0;

	if (asc == 0x11 || asc == 0x30 || asc == 0x31 || asc == 0x53
	    || asc == 0x5a) {
		/* Unrecovered errors */
		return SCSIRET_CONTINUE;
	}
	if (asc == 0x21 && ascq == 0) {
		/* Logical block address out of range */
		return SCSIRET_CONTINUE;
	}
	if (asc == 0x27 && ascq == 0) {
		/* Write protected */
		return SCSIRET_CONTINUE;
	}
	if (asc == 0x28 && ascq == 0) {
		/* Not ready to ready transition */
		/* (medium may have changed) */
		return SCSIRET_CONTINUE;
	}
	if (asc == 0x3a && ascq == 0) {
		/* Medium not present */
		return SCSIRET_CONTINUE;
	}

	/* Retry all disk errors.
	 */
	scsi_sense_print(xs);
	if (xs->retries)
		printf(", retries:%d\n", xs->retries);
	else
		printf(", FAILURE\n");

	return SCSIRET_DO_RETRY;
}

static od_devsw_installed = 0;

static void 	od_drvinit(void *unused)
{

	if( ! od_devsw_installed ) {
		bdevsw_add_generic(BDEV_MAJOR, CDEV_MAJOR, &od_bdevsw);
		od_devsw_installed = 1;
    	}
}

SYSINIT(oddev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,od_drvinit,NULL)