xref: /netbsd-src/sys/dev/scsipi/st.c (revision 76dfffe33547c37f8bdd446e3e4ab0f3c16cea4b)
1 /*	$NetBSD: st.c,v 1.69 1996/10/12 23:23:24 christos Exp $	*/
2 
3 /*
4  * Copyright (c) 1994 Charles Hannum.  All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  * 3. All advertising materials mentioning features or use of this software
15  *    must display the following acknowledgement:
16  *	This product includes software developed by Charles Hannum.
17  * 4. The name of the author may not be used to endorse or promote products
18  *    derived from this software without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
21  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
22  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
23  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
24  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
25  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
29  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30  */
31 
32 /*
33  * Originally written by Julian Elischer (julian@tfs.com)
34  * for TRW Financial Systems for use under the MACH(2.5) operating system.
35  *
36  * TRW Financial Systems, in accordance with their agreement with Carnegie
37  * Mellon University, makes this software available to CMU to distribute
38  * or use in any manner that they see fit as long as this message is kept with
39  * the software. For this reason TFS also grants any other persons or
40  * organisations permission to use or modify this software.
41  *
42  * TFS supplies this software to be publicly redistributed
43  * on the understanding that TFS is not responsible for the correct
44  * functioning of this software in any circumstances.
45  *
46  * Ported to run under 386BSD by Julian Elischer (julian@tfs.com) Sept 1992
47  * major changes by Julian Elischer (julian@jules.dialix.oz.au) May 1993
48  */
49 
50 /*
51  * To do:
52  * work out some better way of guessing what a good timeout is going
53  * to be depending on whether we expect to retension or not.
54  */
55 
56 #include <sys/types.h>
57 #include <sys/param.h>
58 #include <sys/systm.h>
59 #include <sys/fcntl.h>
60 #include <sys/errno.h>
61 #include <sys/ioctl.h>
62 #include <sys/malloc.h>
63 #include <sys/buf.h>
64 #include <sys/proc.h>
65 #include <sys/user.h>
66 #include <sys/mtio.h>
67 #include <sys/device.h>
68 #include <sys/conf.h>
69 
70 #include <scsi/scsi_all.h>
71 #include <scsi/scsi_tape.h>
72 #include <scsi/scsiconf.h>
73 
74 /* Defines for device specific stuff */
75 #define DEF_FIXED_BSIZE  512
76 #define	ST_RETRIES	4	/* only on non IO commands */
77 
78 #define STMODE(z)	( minor(z)       & 0x03)
79 #define STDSTY(z)	((minor(z) >> 2) & 0x03)
80 #define STUNIT(z)	((minor(z) >> 4)       )
81 #define CTLMODE	3
82 
83 /*
84  * Maximum density code known.
85  */
86 #define SCSI_2_MAX_DENSITY_CODE	0x45
87 
88 /*
89  * Define various devices that we know mis-behave in some way,
90  * and note how they are bad, so we can correct for them
91  */
92 struct modes {
93 	u_int quirks;			/* same definitions as in quirkdata */
94 	int blksize;
95 	u_int8_t density;
96 };
97 
98 struct quirkdata {
99 	u_int quirks;
100 #define	ST_Q_FORCE_BLKSIZE	0x0001
101 #define	ST_Q_SENSE_HELP		0x0002	/* must do READ for good MODE SENSE */
102 #define	ST_Q_IGNORE_LOADS	0x0004
103 #define	ST_Q_BLKSIZE		0x0008	/* variable-block media_blksize > 0 */
104 #define	ST_Q_UNIMODAL		0x0010	/* unimode drive rejects mode select */
105 	u_int page_0_size;
106 #define	MAX_PAGE_0_SIZE	64
107 	struct modes modes[4];
108 };
109 
110 struct st_quirk_inquiry_pattern {
111 	struct scsi_inquiry_pattern pattern;
112 	struct quirkdata quirkdata;
113 };
114 
115 struct st_quirk_inquiry_pattern st_quirk_patterns[] = {
116 	{{T_SEQUENTIAL, T_REMOV,
117 	 "        ", "                ", "    "}, {0, 0, {
118 		{ST_Q_FORCE_BLKSIZE, 512, 0},		/* minor 0-3 */
119 		{ST_Q_FORCE_BLKSIZE, 512, QIC_24},	/* minor 4-7 */
120 		{ST_Q_FORCE_BLKSIZE, 0, HALFINCH_1600},	/* minor 8-11 */
121 		{ST_Q_FORCE_BLKSIZE, 0, HALFINCH_6250}	/* minor 12-15 */
122 	}}},
123 	{{T_SEQUENTIAL, T_REMOV,
124 	 "TANDBERG", " TDC 3600       ", ""},     {0, 12, {
125 		{0, 0, 0},				/* minor 0-3 */
126 		{ST_Q_FORCE_BLKSIZE, 0, QIC_525},	/* minor 4-7 */
127 		{0, 0, QIC_150},			/* minor 8-11 */
128 		{0, 0, QIC_120}				/* minor 12-15 */
129 	}}},
130  	{{T_SEQUENTIAL, T_REMOV,
131  	 "TANDBERG", " TDC 3800       ", ""},     {0, 0, {
132 		{ST_Q_FORCE_BLKSIZE, 512, 0},		/* minor 0-3 */
133 		{0, 0, QIC_525},			/* minor 4-7 */
134 		{0, 0, QIC_150},			/* minor 8-11 */
135 		{0, 0, QIC_120}				/* minor 12-15 */
136 	}}},
137 	/*
138 	 * At least -005 and -007 need this.  I'll assume they all do unless I
139 	 * hear otherwise.  - mycroft, 31MAR1994
140 	 */
141 	{{T_SEQUENTIAL, T_REMOV,
142 	 "ARCHIVE ", "VIPER 2525 25462", ""},     {0, 0, {
143 		{ST_Q_SENSE_HELP, 0, 0},		/* minor 0-3 */
144 		{ST_Q_SENSE_HELP, 0, QIC_525},		/* minor 4-7 */
145 		{0, 0, QIC_150},			/* minor 8-11 */
146 		{0, 0, QIC_120}				/* minor 12-15 */
147 	}}},
148 	/*
149 	 * One user reports that this works for his tape drive.  It probably
150 	 * needs more work.  - mycroft, 09APR1994
151 	 */
152 	{{T_SEQUENTIAL, T_REMOV,
153 	 "SANKYO  ", "CP525           ", ""},    {0, 0, {
154 		{ST_Q_FORCE_BLKSIZE, 512, 0},		/* minor 0-3 */
155 		{ST_Q_FORCE_BLKSIZE, 512, QIC_525},	/* minor 4-7 */
156 		{0, 0, QIC_150},			/* minor 8-11 */
157 		{0, 0, QIC_120}				/* minor 12-15 */
158 	}}},
159 	{{T_SEQUENTIAL, T_REMOV,
160 	 "ANRITSU ", "DMT780          ", ""},     {0, 0, {
161 		{ST_Q_FORCE_BLKSIZE, 512, 0},		/* minor 0-3 */
162 		{ST_Q_FORCE_BLKSIZE, 512, QIC_525},	/* minor 4-7 */
163 		{0, 0, QIC_150},			/* minor 8-11 */
164 		{0, 0, QIC_120}				/* minor 12-15 */
165 	}}},
166 	{{T_SEQUENTIAL, T_REMOV,
167 	 "ARCHIVE ", "VIPER 150  21247", ""},     {0, 12, {
168 		{0, 0, 0},				/* minor 0-3 */
169 		{0, 0, QIC_150},			/* minor 4-7 */
170 		{0, 0, QIC_120},			/* minor 8-11 */
171 		{0, 0, QIC_24}				/* minor 12-15 */
172 	}}},
173 	{{T_SEQUENTIAL, T_REMOV,
174 	 "WANGTEK ", "5099ES SCSI", ""},          {0, 0, {
175 		{ST_Q_FORCE_BLKSIZE, 512, 0},		/* minor 0-3 */
176 		{0, 0, QIC_11},				/* minor 4-7 */
177 		{0, 0, QIC_24},				/* minor 8-11 */
178 		{0, 0, QIC_24}				/* minor 12-15 */
179 	}}},
180 	{{T_SEQUENTIAL, T_REMOV,
181 	 "WANGTEK ", "5150ES SCSI", ""},          {0, 0, {
182 		{ST_Q_FORCE_BLKSIZE, 512, 0},		/* minor 0-3 */
183 		{0, 0, QIC_24},				/* minor 4-7 */
184 		{0, 0, QIC_120},			/* minor 8-11 */
185 		{0, 0, QIC_150}				/* minor 12-15 */
186 	}}},
187 	{{T_SEQUENTIAL, T_REMOV,
188 	 "WANGTEK ", "5525ES SCSI REV7", ""},     {0, 0, {
189 		{0, 0, 0},				/* minor 0-3 */
190 		{ST_Q_BLKSIZE, 0, QIC_525},		/* minor 4-7 */
191 		{0, 0, QIC_150},			/* minor 8-11 */
192 		{0, 0, QIC_120}				/* minor 12-15 */
193 	}}},
194 	{{T_SEQUENTIAL, T_REMOV,
195 	 "WangDAT ", "Model 1300      ", ""},     {0, 0, {
196 		{0, 0, 0},				/* minor 0-3 */
197 		{ST_Q_FORCE_BLKSIZE, 512, DDS},		/* minor 4-7 */
198 		{ST_Q_FORCE_BLKSIZE, 1024, DDS},	/* minor 8-11 */
199 		{ST_Q_FORCE_BLKSIZE, 0, DDS}		/* minor 12-15 */
200 	}}},
201 	{{T_SEQUENTIAL, T_REMOV,
202 	 "EXABYTE ", "EXB-8200        ", "263H"}, {0, 5, {
203 		{0, 0, 0},				/* minor 0-3 */
204 		{0, 0, 0},				/* minor 4-7 */
205 		{0, 0, 0},				/* minor 8-11 */
206 		{0, 0, 0}				/* minor 12-15 */
207 	}}},
208 	{{T_SEQUENTIAL, T_REMOV,
209 	 "HP      ", "T4000s          ", ""},     {ST_Q_UNIMODAL, 0, {
210 		{0, 0, QIC_3095},			/* minor 0-3 */
211 		{0, 0, QIC_3095},			/* minor 4-7 */
212 		{0, 0, QIC_3095},			/* minor 8-11 */
213 		{0, 0, QIC_3095},			/* minor 12-15 */
214 	}}},
215 #if 0
216 	{{T_SEQUENTIAL, T_REMOV,
217 	 "EXABYTE ", "EXB-8200        ", ""},     {0, 12, {
218 		{0, 0, 0},				/* minor 0-3 */
219 		{0, 0, 0},				/* minor 4-7 */
220 		{0, 0, 0},				/* minor 8-11 */
221 		{0, 0, 0}				/* minor 12-15 */
222 	}}},
223 #endif
224 };
225 
226 #define NOEJECT 0
227 #define EJECT 1
228 
229 struct st_softc {
230 	struct device sc_dev;
231 /*--------------------present operating parameters, flags etc.----------------*/
232 	int flags;		/* see below                          */
233 	u_int quirks;		/* quirks for the open mode           */
234 	int blksize;		/* blksize we are using                */
235 	u_int8_t density;	/* present density                    */
236 	u_int page_0_size;	/* size of page 0 data		      */
237 	u_int last_dsty;	/* last density opened               */
238 /*--------------------device/scsi parameters----------------------------------*/
239 	struct scsi_link *sc_link;	/* our link to the adpter etc.        */
240 /*--------------------parameters reported by the device ----------------------*/
241 	int blkmin;		/* min blk size                       */
242 	int blkmax;		/* max blk size                       */
243 	struct quirkdata *quirkdata;	/* if we have a rogue entry           */
244 /*--------------------parameters reported by the device for this media--------*/
245 	u_long numblks;		/* nominal blocks capacity            */
246 	int media_blksize;	/* 0 if not ST_FIXEDBLOCKS            */
247 	u_int8_t media_density;	/* this is what it said when asked    */
248 /*--------------------quirks for the whole drive------------------------------*/
249 	u_int drive_quirks;	/* quirks of this drive               */
250 /*--------------------How we should set up when opening each minor device----*/
251 	struct modes modes[4];	/* plus more for each mode            */
252 	u_int8_t  modeflags[4];	/* flags for the modes                */
253 #define DENSITY_SET_BY_USER	0x01
254 #define DENSITY_SET_BY_QUIRK	0x02
255 #define BLKSIZE_SET_BY_USER	0x04
256 #define BLKSIZE_SET_BY_QUIRK	0x08
257 /*--------------------storage for sense data returned by the drive------------*/
258 	u_char sense_data[MAX_PAGE_0_SIZE];	/*
259 						 * additional sense data needed
260 						 * for mode sense/select.
261 						 */
262 	struct buf buf_queue;		/* the queue of pending IO operations */
263 };
264 
265 
266 int	stmatch __P((struct device *, void *, void *));
267 void	stattach __P((struct device *, struct device *, void *));
268 void	st_identify_drive __P((struct st_softc *, struct scsi_inquiry_data *));
269 void	st_loadquirks __P((struct st_softc *));
270 int	st_mount_tape __P((dev_t, int));
271 void	st_unmount __P((struct st_softc *, boolean));
272 int	st_decide_mode __P((struct st_softc *, boolean));
273 void	ststart __P((void *));
274 int	st_read __P((struct st_softc *, char *, int, int));
275 int	st_read_block_limits __P((struct st_softc *, int));
276 int	st_mode_sense __P((struct st_softc *, int));
277 int	st_mode_select __P((struct st_softc *, int));
278 int	st_space __P((struct st_softc *, int, u_int, int));
279 int	st_write_filemarks __P((struct st_softc *, int, int));
280 int	st_check_eod __P((struct st_softc *, boolean, int *, int));
281 int	st_load __P((struct st_softc *, u_int, int));
282 int	st_rewind __P((struct st_softc *, u_int, int));
283 int	st_interpret_sense __P((struct scsi_xfer *));
284 int	st_touch_tape __P((struct st_softc *));
285 int	st_erase __P((struct st_softc *, int full, int flags));
286 
287 struct cfattach st_ca = {
288 	sizeof(struct st_softc), stmatch, stattach
289 };
290 
291 struct cfdriver st_cd = {
292 	NULL, "st", DV_TAPE
293 };
294 
295 struct scsi_device st_switch = {
296 	st_interpret_sense,
297 	ststart,
298 	NULL,
299 	NULL,
300 };
301 
302 #define	ST_INFO_VALID	0x0001
303 #define	ST_BLOCK_SET	0x0002	/* block size, mode set by ioctl      */
304 #define	ST_WRITTEN	0x0004	/* data have been written, EOD needed */
305 #define	ST_FIXEDBLOCKS	0x0008
306 #define	ST_AT_FILEMARK	0x0010
307 #define	ST_EIO_PENDING	0x0020	/* we couldn't report it then (had data) */
308 #define	ST_NEW_MOUNT	0x0040	/* still need to decide mode              */
309 #define	ST_READONLY	0x0080	/* st_mode_sense says write protected */
310 #define	ST_FM_WRITTEN	0x0100	/*
311 				 * EOF file mark written  -- used with
312 				 * ~ST_WRITTEN to indicate that multiple file
313 				 * marks have been written
314 				 */
315 #define	ST_BLANK_READ	0x0200	/* BLANK CHECK encountered already */
316 #define	ST_2FM_AT_EOD	0x0400	/* write 2 file marks at EOD */
317 #define	ST_MOUNTED	0x0800	/* Device is presently mounted */
318 #define	ST_DONTBUFFER	0x1000	/* Disable buffering/caching */
319 
320 #define	ST_PER_ACTION	(ST_AT_FILEMARK | ST_EIO_PENDING | ST_BLANK_READ)
321 #define	ST_PER_MOUNT	(ST_INFO_VALID | ST_BLOCK_SET | ST_WRITTEN | \
322 			 ST_FIXEDBLOCKS | ST_READONLY | ST_FM_WRITTEN | \
323 			 ST_2FM_AT_EOD | ST_PER_ACTION)
324 
325 struct scsi_inquiry_pattern st_patterns[] = {
326 	{T_SEQUENTIAL, T_REMOV,
327 	 "",         "",                 ""},
328 };
329 
330 int
331 stmatch(parent, match, aux)
332 	struct device *parent;
333 	void *match, *aux;
334 {
335 	struct scsibus_attach_args *sa = aux;
336 	int priority;
337 
338 	(void)scsi_inqmatch(sa->sa_inqbuf,
339 	    (caddr_t)st_patterns, sizeof(st_patterns)/sizeof(st_patterns[0]),
340 	    sizeof(st_patterns[0]), &priority);
341 	return (priority);
342 }
343 
344 /*
345  * The routine called by the low level scsi routine when it discovers
346  * A device suitable for this driver
347  */
348 void
349 stattach(parent, self, aux)
350 	struct device *parent, *self;
351 	void *aux;
352 {
353 	struct st_softc *st = (void *)self;
354 	struct scsibus_attach_args *sa = aux;
355 	struct scsi_link *sc_link = sa->sa_sc_link;
356 
357 	SC_DEBUG(sc_link, SDEV_DB2, ("stattach: "));
358 
359 	/*
360 	 * Store information needed to contact our base driver
361 	 */
362 	st->sc_link = sc_link;
363 	sc_link->device = &st_switch;
364 	sc_link->device_softc = st;
365 	sc_link->openings = 1;
366 
367 	/*
368 	 * Check if the drive is a known criminal and take
369 	 * Any steps needed to bring it into line
370 	 */
371 	st_identify_drive(st, sa->sa_inqbuf);
372 
373 	/*
374 	 * Use the subdriver to request information regarding
375 	 * the drive. We cannot use interrupts yet, so the
376 	 * request must specify this.
377 	 */
378 	printf("\n");
379 	printf("%s: %s", st->sc_dev.dv_xname, st->quirkdata ? "rogue, " : "");
380 	if (scsi_test_unit_ready(sc_link,
381 	    SCSI_AUTOCONF | SCSI_SILENT | SCSI_IGNORE_MEDIA_CHANGE) ||
382 	    st_mode_sense(st,
383 	    SCSI_AUTOCONF | SCSI_SILENT | SCSI_IGNORE_MEDIA_CHANGE))
384 		printf("drive empty\n");
385 	else {
386 		printf("density code 0x%x, ", st->media_density);
387 		if (st->media_blksize > 0)
388 			printf("%d-byte", st->media_blksize);
389 		else
390 			printf("variable");
391 		printf(" blocks, write-%s\n",
392 		    (st->flags & ST_READONLY) ? "protected" : "enabled");
393 	}
394 
395 	/*
396 	 * Set up the buf queue for this device
397 	 */
398 	st->buf_queue.b_active = 0;
399 	st->buf_queue.b_actf = 0;
400 	st->buf_queue.b_actb = &st->buf_queue.b_actf;
401 }
402 
403 /*
404  * Use the inquiry routine in 'scsi_base' to get drive info so we can
405  * Further tailor our behaviour.
406  */
407 void
408 st_identify_drive(st, inqbuf)
409 	struct st_softc *st;
410 	struct scsi_inquiry_data *inqbuf;
411 {
412 	struct st_quirk_inquiry_pattern *finger;
413 	int priority;
414 
415 	finger = (struct st_quirk_inquiry_pattern *)scsi_inqmatch(inqbuf,
416 	    (caddr_t)st_quirk_patterns,
417 	    sizeof(st_quirk_patterns)/sizeof(st_quirk_patterns[0]),
418 	    sizeof(st_quirk_patterns[0]), &priority);
419 	if (priority != 0) {
420 		st->quirkdata = &finger->quirkdata;
421 		st->drive_quirks = finger->quirkdata.quirks;
422 		st->quirks = finger->quirkdata.quirks;	/* start value */
423 		st->page_0_size = finger->quirkdata.page_0_size;
424 		st_loadquirks(st);
425 	}
426 }
427 
428 /*
429  * initialise the subdevices to the default (QUIRK) state.
430  * this will remove any setting made by the system operator or previous
431  * operations.
432  */
433 void
434 st_loadquirks(st)
435 	struct st_softc *st;
436 {
437 	int i;
438 	struct	modes *mode;
439 	struct	modes *mode2;
440 
441 	mode = st->quirkdata->modes;
442 	mode2 = st->modes;
443 	for (i = 0; i < 4; i++) {
444 		bzero(mode2, sizeof(struct modes));
445 		st->modeflags[i] &= ~(BLKSIZE_SET_BY_QUIRK |
446 		    DENSITY_SET_BY_QUIRK | BLKSIZE_SET_BY_USER |
447 		    DENSITY_SET_BY_USER);
448 		if ((mode->quirks | st->drive_quirks) & ST_Q_FORCE_BLKSIZE) {
449 			mode2->blksize = mode->blksize;
450 			st->modeflags[i] |= BLKSIZE_SET_BY_QUIRK;
451 		}
452 		if (mode->density) {
453 			mode2->density = mode->density;
454 			st->modeflags[i] |= DENSITY_SET_BY_QUIRK;
455 		}
456 		mode++;
457 		mode2++;
458 	}
459 }
460 
461 /*
462  * open the device.
463  */
464 int
465 stopen(dev, flags, mode, p)
466 	dev_t dev;
467 	int flags;
468 	int mode;
469 	struct proc *p;
470 {
471 	int unit;
472 	u_int stmode, dsty;
473 	int error = 0;
474 	struct st_softc *st;
475 	struct scsi_link *sc_link;
476 
477 	unit = STUNIT(dev);
478 	if (unit >= st_cd.cd_ndevs)
479 		return ENXIO;
480 	st = st_cd.cd_devs[unit];
481 	if (!st)
482 		return ENXIO;
483 
484 	stmode = STMODE(dev);
485 	dsty = STDSTY(dev);
486 	sc_link = st->sc_link;
487 
488 	SC_DEBUG(sc_link, SDEV_DB1, ("open: dev=0x%x (unit %d (of %d))\n", dev,
489 	    unit, st_cd.cd_ndevs));
490 
491 	/*
492 	 * Only allow one at a time
493 	 */
494 	if (sc_link->flags & SDEV_OPEN) {
495 		printf("%s: already open\n", st->sc_dev.dv_xname);
496 		return EBUSY;
497 	}
498 
499 	/*
500 	 * Catch any unit attention errors.
501 	 */
502 	error = scsi_test_unit_ready(sc_link,
503 				     SCSI_IGNORE_MEDIA_CHANGE |
504 				     (stmode == CTLMODE ?
505 					SCSI_IGNORE_NOT_READY : 0));
506 	if (error)
507 		goto bad;
508 
509 	sc_link->flags |= SDEV_OPEN;	/* unit attn are now errors */
510 
511 	/*
512 	 * If the mode is 3 (e.g. minor = 3,7,11,15)
513 	 * then the device has been opened to set defaults
514 	 * This mode does NOT ALLOW I/O, only ioctls
515 	 */
516 	if (stmode == CTLMODE)
517 		return 0;
518 
519 	/*
520 	 * if it's a different mode, or if the media has been
521 	 * invalidated, unmount the tape from the previous
522 	 * session but continue with open processing
523 	 */
524 	if (st->last_dsty != dsty || !(sc_link->flags & SDEV_MEDIA_LOADED))
525 		st_unmount(st, NOEJECT);
526 
527 	/*
528 	 * If we are not mounted, then we should start a new
529 	 * mount session.
530 	 */
531 	if (!(st->flags & ST_MOUNTED)) {
532 		st_mount_tape(dev, flags);
533 		st->last_dsty = dsty;
534 	}
535 
536 	/*
537 	 * Make sure that a tape opened in write-only mode will have
538 	 * file marks written on it when closed, even if not written to.
539 	 * This is for SUN compatibility
540 	 */
541 	if ((flags & O_ACCMODE) == FWRITE)
542 		st->flags |= ST_WRITTEN;
543 
544 	SC_DEBUG(sc_link, SDEV_DB2, ("open complete\n"));
545 	return 0;
546 
547 bad:
548 	st_unmount(st, NOEJECT);
549 	sc_link->flags &= ~SDEV_OPEN;
550 	return error;
551 }
552 
553 /*
554  * close the device.. only called if we are the LAST
555  * occurence of an open device
556  */
557 int
558 stclose(dev, flags, mode, p)
559 	dev_t dev;
560 	int flags;
561 	int mode;
562 	struct proc *p;
563 {
564 	struct st_softc *st = st_cd.cd_devs[STUNIT(dev)];
565 
566 	SC_DEBUG(st->sc_link, SDEV_DB1, ("closing\n"));
567 	if ((st->flags & (ST_WRITTEN | ST_FM_WRITTEN)) == ST_WRITTEN)
568 		st_write_filemarks(st, 1, 0);
569 	switch (STMODE(dev)) {
570 	case 0:
571 	case 3:		/* for now */
572 		st_unmount(st, NOEJECT);
573 		break;
574 	case 1:
575 		/* leave mounted unless media seems to have been removed */
576 		if (!(st->sc_link->flags & SDEV_MEDIA_LOADED))
577 			st_unmount(st, NOEJECT);
578 		break;
579 	case 2:
580 		st_unmount(st, EJECT);
581 		break;
582 	}
583 	st->sc_link->flags &= ~SDEV_OPEN;
584 
585 	return 0;
586 }
587 
588 /*
589  * Start a new mount session.
590  * Copy in all the default parameters from the selected device mode.
591  * and try guess any that seem to be defaulted.
592  */
593 int
594 st_mount_tape(dev, flags)
595 	dev_t dev;
596 	int flags;
597 {
598 	int unit;
599 	u_int mode, dsty;
600 	struct st_softc *st;
601 	struct scsi_link *sc_link;
602 	int error = 0;
603 
604 	unit = STUNIT(dev);
605 	mode = STMODE(dev);
606 	dsty = STDSTY(dev);
607 	st = st_cd.cd_devs[unit];
608 	sc_link = st->sc_link;
609 
610 	if (st->flags & ST_MOUNTED)
611 		return 0;
612 
613 	SC_DEBUG(sc_link, SDEV_DB1, ("mounting\n "));
614 	st->flags |= ST_NEW_MOUNT;
615 	st->quirks = st->drive_quirks | st->modes[dsty].quirks;
616 	/*
617 	 * If the media is new, then make sure we give it a chance to
618 	 * to do a 'load' instruction.  (We assume it is new.)
619 	 */
620 	if ((error = st_load(st, LD_LOAD, 0)) != 0)
621 		return error;
622 	/*
623 	 * Throw another dummy instruction to catch
624 	 * 'Unit attention' errors. Some drives appear to give
625 	 * these after doing a Load instruction.
626 	 * (noteably some DAT drives)
627 	 */
628 	scsi_test_unit_ready(sc_link, SCSI_SILENT);	/* XXX */
629 
630 	/*
631 	 * Some devices can't tell you much until they have been
632 	 * asked to look at the media. This quirk does this.
633 	 */
634 	if (st->quirks & ST_Q_SENSE_HELP)
635 		if ((error = st_touch_tape(st)) != 0)
636 			return error;
637 	/*
638 	 * Load the physical device parameters
639 	 * loads: blkmin, blkmax
640 	 */
641 	if ((error = st_read_block_limits(st, 0)) != 0)
642 		return error;
643 	/*
644 	 * Load the media dependent parameters
645 	 * includes: media_blksize,media_density,numblks
646 	 * As we have a tape in, it should be reflected here.
647 	 * If not you may need the "quirk" above.
648 	 */
649 	if ((error = st_mode_sense(st, 0)) != 0)
650 		return error;
651 	/*
652 	 * If we have gained a permanent density from somewhere,
653 	 * then use it in preference to the one supplied by
654 	 * default by the driver.
655 	 */
656 	if (st->modeflags[dsty] & (DENSITY_SET_BY_QUIRK | DENSITY_SET_BY_USER))
657 		st->density = st->modes[dsty].density;
658 	else
659 		st->density = st->media_density;
660 	/*
661 	 * If we have gained a permanent blocksize
662 	 * then use it in preference to the one supplied by
663 	 * default by the driver.
664 	 */
665 	st->flags &= ~ST_FIXEDBLOCKS;
666 	if (st->modeflags[dsty] & (BLKSIZE_SET_BY_QUIRK | BLKSIZE_SET_BY_USER)) {
667 		st->blksize = st->modes[dsty].blksize;
668 		if (st->blksize)
669 			st->flags |= ST_FIXEDBLOCKS;
670 	} else {
671 		if ((error = st_decide_mode(st, FALSE)) != 0)
672 			return error;
673 	}
674 	if ((error = st_mode_select(st, 0)) != 0) {
675 		printf("%s: cannot set selected mode\n", st->sc_dev.dv_xname);
676 		return error;
677 	}
678 	scsi_prevent(sc_link, PR_PREVENT,
679 	    SCSI_IGNORE_ILLEGAL_REQUEST | SCSI_IGNORE_NOT_READY);
680 	st->flags &= ~ST_NEW_MOUNT;
681 	st->flags |= ST_MOUNTED;
682 	sc_link->flags |= SDEV_MEDIA_LOADED;	/* move earlier? */
683 
684 	return 0;
685 }
686 
687 /*
688  * End the present mount session.
689  * Rewind, and optionally eject the tape.
690  * Reset various flags to indicate that all new
691  * operations require another mount operation
692  */
693 void
694 st_unmount(st, eject)
695 	struct st_softc *st;
696 	boolean eject;
697 {
698 	struct scsi_link *sc_link = st->sc_link;
699 	int nmarks;
700 
701 	if (!(st->flags & ST_MOUNTED))
702 		return;
703 	SC_DEBUG(sc_link, SDEV_DB1, ("unmounting\n"));
704 	st_check_eod(st, FALSE, &nmarks, SCSI_IGNORE_NOT_READY);
705 	st_rewind(st, 0, SCSI_IGNORE_NOT_READY);
706 	scsi_prevent(sc_link, PR_ALLOW,
707 	    SCSI_IGNORE_ILLEGAL_REQUEST | SCSI_IGNORE_NOT_READY);
708 	if (eject)
709 		st_load(st, LD_UNLOAD, SCSI_IGNORE_NOT_READY);
710 	st->flags &= ~(ST_MOUNTED | ST_NEW_MOUNT);
711 	sc_link->flags &= ~SDEV_MEDIA_LOADED;
712 }
713 
714 /*
715  * Given all we know about the device, media, mode, 'quirks' and
716  * initial operation, make a decision as to how we should be set
717  * to run (regarding blocking and EOD marks)
718  */
719 int
720 st_decide_mode(st, first_read)
721 	struct st_softc *st;
722 	boolean	first_read;
723 {
724 #ifdef SCSIDEBUG
725 	struct scsi_link *sc_link = st->sc_link;
726 #endif
727 
728 	SC_DEBUG(sc_link, SDEV_DB2, ("starting block mode decision\n"));
729 
730 	/*
731 	 * If the drive can only handle fixed-length blocks and only at
732 	 * one size, perhaps we should just do that.
733 	 */
734 	if (st->blkmin && (st->blkmin == st->blkmax)) {
735 		st->flags |= ST_FIXEDBLOCKS;
736 		st->blksize = st->blkmin;
737 		SC_DEBUG(sc_link, SDEV_DB3,
738 		    ("blkmin == blkmax of %d\n", st->blkmin));
739 		goto done;
740 	}
741 	/*
742 	 * If the tape density mandates (or even suggests) use of fixed
743 	 * or variable-length blocks, comply.
744 	 */
745 	switch (st->density) {
746 	case HALFINCH_800:
747 	case HALFINCH_1600:
748 	case HALFINCH_6250:
749 	case DDS:
750 		st->flags &= ~ST_FIXEDBLOCKS;
751 		st->blksize = 0;
752 		SC_DEBUG(sc_link, SDEV_DB3, ("density specified variable\n"));
753 		goto done;
754 	case QIC_11:
755 	case QIC_24:
756 	case QIC_120:
757 	case QIC_150:
758 	case QIC_525:
759 	case QIC_1320:
760 		st->flags |= ST_FIXEDBLOCKS;
761 		if (st->media_blksize > 0)
762 			st->blksize = st->media_blksize;
763 		else
764 			st->blksize = DEF_FIXED_BSIZE;
765 		SC_DEBUG(sc_link, SDEV_DB3, ("density specified fixed\n"));
766 		goto done;
767 	}
768 	/*
769 	 * If we're about to read the tape, perhaps we should choose
770 	 * fixed or variable-length blocks and block size according to
771 	 * what the drive found on the tape.
772 	 */
773 	if (first_read &&
774 	    (!(st->quirks & ST_Q_BLKSIZE) || (st->media_blksize == 0) ||
775 	    (st->media_blksize == DEF_FIXED_BSIZE) ||
776 	    (st->media_blksize == 1024))) {
777 		if (st->media_blksize > 0)
778 			st->flags |= ST_FIXEDBLOCKS;
779 		else
780 			st->flags &= ~ST_FIXEDBLOCKS;
781 		st->blksize = st->media_blksize;
782 		SC_DEBUG(sc_link, SDEV_DB3,
783 		    ("Used media_blksize of %d\n", st->media_blksize));
784 		goto done;
785 	}
786 	/*
787 	 * We're getting no hints from any direction.  Choose variable-
788 	 * length blocks arbitrarily.
789 	 */
790 	st->flags &= ~ST_FIXEDBLOCKS;
791 	st->blksize = 0;
792 	SC_DEBUG(sc_link, SDEV_DB3,
793 	    ("Give up and default to variable mode\n"));
794 
795 done:
796 	/*
797 	 * Decide whether or not to write two file marks to signify end-
798 	 * of-data.  Make the decision as a function of density.  If
799 	 * the decision is not to use a second file mark, the SCSI BLANK
800 	 * CHECK condition code will be recognized as end-of-data when
801 	 * first read.
802 	 * (I think this should be a by-product of fixed/variable..julian)
803 	 */
804 	switch (st->density) {
805 /*      case 8 mm:   What is the SCSI density code for 8 mm, anyway? */
806 	case QIC_11:
807 	case QIC_24:
808 	case QIC_120:
809 	case QIC_150:
810 	case QIC_525:
811 	case QIC_1320:
812 		st->flags &= ~ST_2FM_AT_EOD;
813 		break;
814 	default:
815 		st->flags |= ST_2FM_AT_EOD;
816 	}
817 	return 0;
818 }
819 
820 /*
821  * Actually translate the requested transfer into
822  * one the physical driver can understand
823  * The transfer is described by a buf and will include
824  * only one physical transfer.
825  */
826 void
827 ststrategy(bp)
828 	struct buf *bp;
829 {
830 	struct st_softc *st = st_cd.cd_devs[STUNIT(bp->b_dev)];
831 	struct buf *dp;
832 	int s;
833 
834 	SC_DEBUG(st->sc_link, SDEV_DB1,
835 	    ("ststrategy %ld bytes @ blk %d\n", bp->b_bcount, bp->b_blkno));
836 	/*
837 	 * If it's a null transfer, return immediatly
838 	 */
839 	if (bp->b_bcount == 0)
840 		goto done;
841 	/*
842 	 * Odd sized request on fixed drives are verboten
843 	 */
844 	if (st->flags & ST_FIXEDBLOCKS) {
845 		if (bp->b_bcount % st->blksize) {
846 			printf("%s: bad request, must be multiple of %d\n",
847 			    st->sc_dev.dv_xname, st->blksize);
848 			bp->b_error = EIO;
849 			goto bad;
850 		}
851 	}
852 	/*
853 	 * as are out-of-range requests on variable drives.
854 	 */
855 	else if (bp->b_bcount < st->blkmin ||
856 		 (st->blkmax && bp->b_bcount > st->blkmax)) {
857 		printf("%s: bad request, must be between %d and %d\n",
858 		    st->sc_dev.dv_xname, st->blkmin, st->blkmax);
859 		bp->b_error = EIO;
860 		goto bad;
861 	}
862 	s = splbio();
863 
864 	/*
865 	 * Place it in the queue of activities for this tape
866 	 * at the end (a bit silly because we only have on user..
867 	 * (but it could fork()))
868 	 */
869 	dp = &st->buf_queue;
870 	bp->b_actf = NULL;
871 	bp->b_actb = dp->b_actb;
872 	*dp->b_actb = bp;
873 	dp->b_actb = &bp->b_actf;
874 
875 	/*
876 	 * Tell the device to get going on the transfer if it's
877 	 * not doing anything, otherwise just wait for completion
878 	 * (All a bit silly if we're only allowing 1 open but..)
879 	 */
880 	ststart(st);
881 
882 	splx(s);
883 	return;
884 bad:
885 	bp->b_flags |= B_ERROR;
886 done:
887 	/*
888 	 * Correctly set the buf to indicate a completed xfer
889 	 */
890 	bp->b_resid = bp->b_bcount;
891 	biodone(bp);
892 	return;
893 }
894 
895 /*
896  * ststart looks to see if there is a buf waiting for the device
897  * and that the device is not already busy. If both are true,
898  * It dequeues the buf and creates a scsi command to perform the
899  * transfer required. The transfer request will call scsi_done
900  * on completion, which will in turn call this routine again
901  * so that the next queued transfer is performed.
902  * The bufs are queued by the strategy routine (ststrategy)
903  *
904  * This routine is also called after other non-queued requests
905  * have been made of the scsi driver, to ensure that the queue
906  * continues to be drained.
907  * ststart() is called at splbio
908  */
909 void
910 ststart(v)
911 	void *v;
912 {
913 	struct st_softc *st = v;
914 	struct scsi_link *sc_link = st->sc_link;
915 	register struct buf *bp, *dp;
916 	struct scsi_rw_tape cmd;
917 	int flags;
918 
919 	SC_DEBUG(sc_link, SDEV_DB2, ("ststart "));
920 	/*
921 	 * See if there is a buf to do and we are not already
922 	 * doing one
923 	 */
924 	while (sc_link->openings > 0) {
925 		/* if a special awaits, let it proceed first */
926 		if (sc_link->flags & SDEV_WAITING) {
927 			sc_link->flags &= ~SDEV_WAITING;
928 			wakeup((caddr_t)sc_link);
929 			return;
930 		}
931 
932 		dp = &st->buf_queue;
933 		if ((bp = dp->b_actf) == NULL)
934 			return;
935 		if ((dp = bp->b_actf) != NULL)
936 			dp->b_actb = bp->b_actb;
937 		else
938 			st->buf_queue.b_actb = bp->b_actb;
939 		*bp->b_actb = dp;
940 
941 		/*
942 		 * if the device has been unmounted byt the user
943 		 * then throw away all requests until done
944 		 */
945 		if (!(st->flags & ST_MOUNTED) ||
946 		    !(sc_link->flags & SDEV_MEDIA_LOADED)) {
947 			/* make sure that one implies the other.. */
948 			sc_link->flags &= ~SDEV_MEDIA_LOADED;
949 			bp->b_flags |= B_ERROR;
950 			bp->b_error = EIO;
951 			biodone(bp);
952 			continue;
953 		}
954 		/*
955 		 * only FIXEDBLOCK devices have pending operations
956 		 */
957 		if (st->flags & ST_FIXEDBLOCKS) {
958 			/*
959 			 * If we are at a filemark but have not reported it yet
960 			 * then we should report it now
961 			 */
962 			if (st->flags & ST_AT_FILEMARK) {
963 				if ((bp->b_flags & B_READ) == B_WRITE) {
964 					/*
965 					 * Handling of ST_AT_FILEMARK in
966 					 * st_space will fill in the right file
967 					 * mark count.
968 					 * Back up over filemark
969 					 */
970 					if (st_space(st, 0, SP_FILEMARKS, 0)) {
971 						bp->b_flags |= B_ERROR;
972 						bp->b_error = EIO;
973 						biodone(bp);
974 						continue;
975 					}
976 				} else {
977 					bp->b_resid = bp->b_bcount;
978 					bp->b_error = 0;
979 					bp->b_flags &= ~B_ERROR;
980 					st->flags &= ~ST_AT_FILEMARK;
981 					biodone(bp);
982 					continue;	/* seek more work */
983 				}
984 			}
985 			/*
986 			 * If we are at EIO (e.g. EOM) but have not reported it
987 			 * yet then we should report it now
988 			 */
989 			if (st->flags & ST_EIO_PENDING) {
990 				bp->b_resid = bp->b_bcount;
991 				bp->b_error = EIO;
992 				bp->b_flags |= B_ERROR;
993 				st->flags &= ~ST_EIO_PENDING;
994 				biodone(bp);
995 				continue;	/* seek more work */
996 			}
997 		}
998 
999 		/*
1000 		 *  Fill out the scsi command
1001 		 */
1002 		bzero(&cmd, sizeof(cmd));
1003 		if ((bp->b_flags & B_READ) == B_WRITE) {
1004 			cmd.opcode = WRITE;
1005 			st->flags &= ~ST_FM_WRITTEN;
1006 			st->flags |= ST_WRITTEN;
1007 			flags = SCSI_DATA_OUT;
1008 		} else {
1009 			cmd.opcode = READ;
1010 			flags = SCSI_DATA_IN;
1011 		}
1012 
1013 		/*
1014 		 * Handle "fixed-block-mode" tape drives by using the
1015 		 * block count instead of the length.
1016 		 */
1017 		if (st->flags & ST_FIXEDBLOCKS) {
1018 			cmd.byte2 |= SRW_FIXED;
1019 			_lto3b(bp->b_bcount / st->blksize, cmd.len);
1020 		} else
1021 			_lto3b(bp->b_bcount, cmd.len);
1022 
1023 		/*
1024 		 * go ask the adapter to do all this for us
1025 		 */
1026 		if (scsi_scsi_cmd(sc_link, (struct scsi_generic *) &cmd,
1027 		    sizeof(cmd), (u_char *) bp->b_data, bp->b_bcount, 0,
1028 		    100000, bp, flags | SCSI_NOSLEEP))
1029 			printf("%s: not queued\n", st->sc_dev.dv_xname);
1030 	} /* go back and see if we can cram more work in.. */
1031 }
1032 
1033 int
1034 stread(dev, uio, iomode)
1035 	dev_t dev;
1036 	struct uio *uio;
1037 	int iomode;
1038 {
1039 	struct st_softc *st = st_cd.cd_devs[STUNIT(dev)];
1040 
1041 	return (physio(ststrategy, NULL, dev, B_READ,
1042 		       st->sc_link->adapter->scsi_minphys, uio));
1043 }
1044 
1045 int
1046 stwrite(dev, uio, iomode)
1047 	dev_t dev;
1048 	struct uio *uio;
1049 	int iomode;
1050 {
1051 	struct st_softc *st = st_cd.cd_devs[STUNIT(dev)];
1052 
1053 	return (physio(ststrategy, NULL, dev, B_WRITE,
1054 		       st->sc_link->adapter->scsi_minphys, uio));
1055 }
1056 
1057 /*
1058  * Perform special action on behalf of the user;
1059  * knows about the internals of this device
1060  */
1061 int
1062 stioctl(dev, cmd, arg, flag, p)
1063 	dev_t dev;
1064 	u_long cmd;
1065 	caddr_t arg;
1066 	int flag;
1067 	struct proc *p;
1068 {
1069 	int error = 0;
1070 	int unit;
1071 	int number, nmarks, dsty;
1072 	int flags;
1073 	struct st_softc *st;
1074 	int hold_blksize;
1075 	u_int8_t hold_density;
1076 	struct mtop *mt = (struct mtop *) arg;
1077 
1078 	/*
1079 	 * Find the device that the user is talking about
1080 	 */
1081 	flags = 0;		/* give error messages, act on errors etc. */
1082 	unit = STUNIT(dev);
1083 	dsty = STDSTY(dev);
1084 	st = st_cd.cd_devs[unit];
1085 	hold_blksize = st->blksize;
1086 	hold_density = st->density;
1087 
1088 	switch (cmd) {
1089 
1090 	case MTIOCGET: {
1091 		struct mtget *g = (struct mtget *) arg;
1092 
1093 		SC_DEBUG(st->sc_link, SDEV_DB1, ("[ioctl: get status]\n"));
1094 		bzero(g, sizeof(struct mtget));
1095 		g->mt_type = 0x7;	/* Ultrix compat *//*? */
1096 		g->mt_blksiz = st->blksize;
1097 		g->mt_density = st->density;
1098 		g->mt_mblksiz[0] = st->modes[0].blksize;
1099 		g->mt_mblksiz[1] = st->modes[1].blksize;
1100 		g->mt_mblksiz[2] = st->modes[2].blksize;
1101 		g->mt_mblksiz[3] = st->modes[3].blksize;
1102 		g->mt_mdensity[0] = st->modes[0].density;
1103 		g->mt_mdensity[1] = st->modes[1].density;
1104 		g->mt_mdensity[2] = st->modes[2].density;
1105 		g->mt_mdensity[3] = st->modes[3].density;
1106 		break;
1107 	}
1108 	case MTIOCTOP: {
1109 
1110 		SC_DEBUG(st->sc_link, SDEV_DB1,
1111 		    ("[ioctl: op=0x%x count=0x%x]\n", mt->mt_op, mt->mt_count));
1112 
1113 		/* compat: in U*x it is a short */
1114 		number = mt->mt_count;
1115 		switch ((short) (mt->mt_op)) {
1116 		case MTWEOF:	/* write an end-of-file record */
1117 			error = st_write_filemarks(st, number, flags);
1118 			break;
1119 		case MTBSF:	/* backward space file */
1120 			number = -number;
1121 		case MTFSF:	/* forward space file */
1122 			error = st_check_eod(st, FALSE, &nmarks, flags);
1123 			if (!error)
1124 				error = st_space(st, number - nmarks,
1125 				    SP_FILEMARKS, flags);
1126 			break;
1127 		case MTBSR:	/* backward space record */
1128 			number = -number;
1129 		case MTFSR:	/* forward space record */
1130 			error = st_check_eod(st, TRUE, &nmarks, flags);
1131 			if (!error)
1132 				error = st_space(st, number, SP_BLKS, flags);
1133 			break;
1134 		case MTREW:	/* rewind */
1135 			error = st_rewind(st, 0, flags);
1136 			break;
1137 		case MTOFFL:	/* rewind and put the drive offline */
1138 			st_unmount(st, EJECT);
1139 			break;
1140 		case MTNOP:	/* no operation, sets status only */
1141 			break;
1142 		case MTRETEN:	/* retension the tape */
1143 			error = st_load(st, LD_RETENSION, flags);
1144 			if (!error)
1145 				error = st_load(st, LD_LOAD, flags);
1146 			break;
1147 		case MTEOM:	/* forward space to end of media */
1148 			error = st_check_eod(st, FALSE, &nmarks, flags);
1149 			if (!error)
1150 				error = st_space(st, 1, SP_EOM, flags);
1151 			break;
1152 		case MTCACHE:	/* enable controller cache */
1153 			st->flags &= ~ST_DONTBUFFER;
1154 			goto try_new_value;
1155 		case MTNOCACHE:	/* disable controller cache */
1156 			st->flags |= ST_DONTBUFFER;
1157 			goto try_new_value;
1158 		case MTERASE:	/* erase volume */
1159 			error = st_erase(st, number, flags);
1160 			break;
1161 		case MTSETBSIZ:	/* Set block size for device */
1162 #ifdef	NOTYET
1163 			if (!(st->flags & ST_NEW_MOUNT)) {
1164 				uprintf("re-mount tape before changing blocksize");
1165 				error = EINVAL;
1166 				break;
1167 			}
1168 #endif
1169 			if (number == 0) {
1170 				st->flags &= ~ST_FIXEDBLOCKS;
1171 			} else {
1172 				if ((st->blkmin || st->blkmax) &&
1173 				    (number < st->blkmin ||
1174 				    number > st->blkmax)) {
1175 					error = EINVAL;
1176 					break;
1177 				}
1178 				st->flags |= ST_FIXEDBLOCKS;
1179 			}
1180 			st->blksize = number;
1181 			st->flags |= ST_BLOCK_SET;	/*XXX */
1182 			goto try_new_value;
1183 
1184 		case MTSETDNSTY:	/* Set density for device and mode */
1185 			if (number > SCSI_2_MAX_DENSITY_CODE) {
1186 				error = EINVAL;
1187 				break;
1188 			} else
1189 				st->density = number;
1190 			goto try_new_value;
1191 
1192 		default:
1193 			error = EINVAL;
1194 		}
1195 		break;
1196 	}
1197 	case MTIOCIEOT:
1198 	case MTIOCEEOT:
1199 		break;
1200 	default:
1201 		if (STMODE(dev) == CTLMODE)
1202 			error = scsi_do_ioctl(st->sc_link, dev, cmd, arg, flag, p);
1203 		else
1204 			error = ENOTTY;
1205 		break;
1206 	}
1207 	return error;
1208 /*-----------------------------*/
1209 try_new_value:
1210 	/*
1211 	 * Check that the mode being asked for is aggreeable to the
1212 	 * drive. If not, put it back the way it was.
1213 	 */
1214 	if ((error = st_mode_select(st, 0)) != 0) {/* put it back as it was */
1215 		printf("%s: cannot set selected mode\n", st->sc_dev.dv_xname);
1216 		st->density = hold_density;
1217 		st->blksize = hold_blksize;
1218 		if (st->blksize)
1219 			st->flags |= ST_FIXEDBLOCKS;
1220 		else
1221 			st->flags &= ~ST_FIXEDBLOCKS;
1222 		return error;
1223 	}
1224 	/*
1225 	 * As the drive liked it, if we are setting a new default,
1226 	 * set it into the structures as such.
1227 	 *
1228 	 * The means for deciding this are not finalised yet
1229 	 */
1230 	if (STMODE(dev) == 0x03) {
1231 		/* special mode */
1232 		/* XXX */
1233 		switch ((short) (mt->mt_op)) {
1234 		case MTSETBSIZ:
1235 			st->modes[dsty].blksize = st->blksize;
1236 			st->modeflags[dsty] |= BLKSIZE_SET_BY_USER;
1237 			break;
1238 		case MTSETDNSTY:
1239 			st->modes[dsty].density = st->density;
1240 			st->modeflags[dsty] |= DENSITY_SET_BY_USER;
1241 			break;
1242 		}
1243 	}
1244 	return 0;
1245 }
1246 
1247 /*
1248  * Do a synchronous read.
1249  */
1250 int
1251 st_read(st, buf, size, flags)
1252 	struct st_softc *st;
1253 	int size;
1254 	int flags;
1255 	char *buf;
1256 {
1257 	struct scsi_rw_tape cmd;
1258 
1259 	/*
1260 	 * If it's a null transfer, return immediatly
1261 	 */
1262 	if (size == 0)
1263 		return 0;
1264 	bzero(&cmd, sizeof(cmd));
1265 	cmd.opcode = READ;
1266 	if (st->flags & ST_FIXEDBLOCKS) {
1267 		cmd.byte2 |= SRW_FIXED;
1268 		_lto3b(size / (st->blksize ? st->blksize : DEF_FIXED_BSIZE),
1269 		    cmd.len);
1270 	} else
1271 		_lto3b(size, cmd.len);
1272 	return scsi_scsi_cmd(st->sc_link, (struct scsi_generic *) &cmd,
1273 	    sizeof(cmd), (u_char *) buf, size, 0, 100000, NULL,
1274 	    flags | SCSI_DATA_IN);
1275 }
1276 
1277 /*
1278  * Ask the drive what it's min and max blk sizes are.
1279  */
1280 int
1281 st_read_block_limits(st, flags)
1282 	struct st_softc *st;
1283 	int flags;
1284 {
1285 	struct scsi_block_limits cmd;
1286 	struct scsi_block_limits_data block_limits;
1287 	struct scsi_link *sc_link = st->sc_link;
1288 	int error;
1289 
1290 	/*
1291 	 * First check if we have it all loaded
1292 	 */
1293 	if ((sc_link->flags & SDEV_MEDIA_LOADED))
1294 		return 0;
1295 
1296 	/*
1297 	 * do a 'Read Block Limits'
1298 	 */
1299 	bzero(&cmd, sizeof(cmd));
1300 	cmd.opcode = READ_BLOCK_LIMITS;
1301 
1302 	/*
1303 	 * do the command, update the global values
1304 	 */
1305 	error = scsi_scsi_cmd(sc_link, (struct scsi_generic *) &cmd,
1306 			      sizeof(cmd), (u_char *) &block_limits,
1307 			      sizeof(block_limits), ST_RETRIES, 5000,
1308 			      NULL, flags | SCSI_DATA_IN);
1309 	if (error)
1310 		return error;
1311 
1312 	st->blkmin = _2btol(block_limits.min_length);
1313 	st->blkmax = _3btol(block_limits.max_length);
1314 
1315 	SC_DEBUG(sc_link, SDEV_DB3,
1316 	    ("(%d <= blksize <= %d)\n", st->blkmin, st->blkmax));
1317 	return 0;
1318 }
1319 
1320 /*
1321  * Get the scsi driver to send a full inquiry to the
1322  * device and use the results to fill out the global
1323  * parameter structure.
1324  *
1325  * called from:
1326  * attach
1327  * open
1328  * ioctl (to reset original blksize)
1329  */
1330 int
1331 st_mode_sense(st, flags)
1332 	struct st_softc *st;
1333 	int flags;
1334 {
1335 	u_int scsi_sense_len;
1336 	int error;
1337 	struct scsi_mode_sense cmd;
1338 	struct scsi_sense {
1339 		struct scsi_mode_header header;
1340 		struct scsi_blk_desc blk_desc;
1341 		u_char sense_data[MAX_PAGE_0_SIZE];
1342 	} scsi_sense;
1343 	struct scsi_link *sc_link = st->sc_link;
1344 
1345 	scsi_sense_len = 12 + st->page_0_size;
1346 
1347 	/*
1348 	 * Set up a mode sense
1349 	 */
1350 	bzero(&cmd, sizeof(cmd));
1351 	cmd.opcode = MODE_SENSE;
1352 	cmd.length = scsi_sense_len;
1353 
1354 	/*
1355 	 * do the command, but we don't need the results
1356 	 * just print them for our interest's sake, if asked,
1357 	 * or if we need it as a template for the mode select
1358 	 * store it away.
1359 	 */
1360 	error = scsi_scsi_cmd(sc_link, (struct scsi_generic *) &cmd,
1361 			      sizeof(cmd), (u_char *) &scsi_sense,
1362 			      scsi_sense_len, ST_RETRIES, 5000, NULL,
1363 			      flags | SCSI_DATA_IN);
1364 	if (error)
1365 		return error;
1366 
1367 	st->numblks = _3btol(scsi_sense.blk_desc.nblocks);
1368 	st->media_blksize = _3btol(scsi_sense.blk_desc.blklen);
1369 	st->media_density = scsi_sense.blk_desc.density;
1370 	if (scsi_sense.header.dev_spec & SMH_DSP_WRITE_PROT)
1371 		st->flags |= ST_READONLY;
1372 	SC_DEBUG(sc_link, SDEV_DB3,
1373 	    ("density code 0x%x, %d-byte blocks, write-%s, ",
1374 	    st->media_density, st->media_blksize,
1375 	    st->flags & ST_READONLY ? "protected" : "enabled"));
1376 	SC_DEBUG(sc_link, SDEV_DB3,
1377 	    ("%sbuffered\n",
1378 	    scsi_sense.header.dev_spec & SMH_DSP_BUFF_MODE ? "" : "un"));
1379 	if (st->page_0_size)
1380 		bcopy(scsi_sense.sense_data, st->sense_data, st->page_0_size);
1381 	sc_link->flags |= SDEV_MEDIA_LOADED;
1382 	return 0;
1383 }
1384 
1385 /*
1386  * Send a filled out parameter structure to the drive to
1387  * set it into the desire modes etc.
1388  */
1389 int
1390 st_mode_select(st, flags)
1391 	struct st_softc *st;
1392 	int flags;
1393 {
1394 	u_int scsi_select_len;
1395 	struct scsi_mode_select cmd;
1396 	struct scsi_select {
1397 		struct scsi_mode_header header;
1398 		struct scsi_blk_desc blk_desc;
1399 		u_char sense_data[MAX_PAGE_0_SIZE];
1400 	} scsi_select;
1401 	struct scsi_link *sc_link = st->sc_link;
1402 
1403 	scsi_select_len = 12 + st->page_0_size;
1404 
1405 	/*
1406 	 * This quirk deals with drives that have only one valid mode
1407 	 * and think this gives them license to reject all mode selects,
1408 	 * even if the selected mode is the one that is supported.
1409 	 */
1410 	if (st->quirks & ST_Q_UNIMODAL) {
1411 		SC_DEBUG(sc_link, SDEV_DB3,
1412 		    ("not setting density 0x%x blksize 0x%x\n",
1413 		    st->density, st->blksize));
1414 		return 0;
1415 	}
1416 
1417 	/*
1418 	 * Set up for a mode select
1419 	 */
1420 	bzero(&cmd, sizeof(cmd));
1421 	cmd.opcode = MODE_SELECT;
1422 	cmd.length = scsi_select_len;
1423 
1424 	bzero(&scsi_select, scsi_select_len);
1425 	scsi_select.header.blk_desc_len = sizeof(struct scsi_blk_desc);
1426 	scsi_select.header.dev_spec &= ~SMH_DSP_BUFF_MODE;
1427 	scsi_select.blk_desc.density = st->density;
1428 	if (st->flags & ST_DONTBUFFER)
1429 		scsi_select.header.dev_spec |= SMH_DSP_BUFF_MODE_OFF;
1430 	else
1431 		scsi_select.header.dev_spec |= SMH_DSP_BUFF_MODE_ON;
1432 	if (st->flags & ST_FIXEDBLOCKS)
1433 		_lto3b(st->blksize, scsi_select.blk_desc.blklen);
1434 	if (st->page_0_size)
1435 		bcopy(st->sense_data, scsi_select.sense_data, st->page_0_size);
1436 
1437 	/*
1438 	 * do the command
1439 	 */
1440 	return scsi_scsi_cmd(sc_link, (struct scsi_generic *) &cmd,
1441 	    sizeof(cmd), (u_char *) &scsi_select, scsi_select_len,
1442 	    ST_RETRIES, 5000, NULL, flags | SCSI_DATA_OUT);
1443 }
1444 
1445 /*
1446  * issue an erase command
1447  */
1448 int
1449 st_erase(st, full, flags)
1450 	struct st_softc *st;
1451 	int full, flags;
1452 {
1453 	struct scsi_erase cmd;
1454 
1455 	/*
1456 	 * Full erase means set LONG bit in erase command, which asks
1457 	 * the drive to erase the entire unit.  Without this bit, we're
1458 	 * asking the drive to write an erase gap.
1459 	 */
1460 	bzero(&cmd, sizeof(cmd));
1461 	cmd.opcode = ERASE;
1462 	if (full)
1463 		cmd.byte2 = SE_IMMED|SE_LONG;
1464 	else
1465 		cmd.byte2 = SE_IMMED;
1466 
1467 	/*
1468 	 * XXX We always do this asynchronously, for now.  How long should
1469 	 * we wait if we want to (eventually) to it synchronously?
1470 	 */
1471 	return (scsi_scsi_cmd(st->sc_link, (struct scsi_generic *)&cmd,
1472 	    sizeof(cmd), 0, 0, ST_RETRIES, 5000, NULL, flags));
1473 }
1474 
1475 /*
1476  * skip N blocks/filemarks/seq filemarks/eom
1477  */
1478 int
1479 st_space(st, number, what, flags)
1480 	struct st_softc *st;
1481 	u_int what;
1482 	int flags;
1483 	int number;
1484 {
1485 	struct scsi_space cmd;
1486 	int error;
1487 
1488 	switch (what) {
1489 	case SP_BLKS:
1490 		if (st->flags & ST_PER_ACTION) {
1491 			if (number > 0) {
1492 				st->flags &= ~ST_PER_ACTION;
1493 				return EIO;
1494 			} else if (number < 0) {
1495 				if (st->flags & ST_AT_FILEMARK) {
1496 					/*
1497 					 * Handling of ST_AT_FILEMARK
1498 					 * in st_space will fill in the
1499 					 * right file mark count.
1500 					 */
1501 					error = st_space(st, 0, SP_FILEMARKS,
1502 						flags);
1503 					if (error)
1504 						return error;
1505 				}
1506 				if (st->flags & ST_BLANK_READ) {
1507 					st->flags &= ~ST_BLANK_READ;
1508 					return EIO;
1509 				}
1510 				st->flags &= ~ST_EIO_PENDING;
1511 			}
1512 		}
1513 		break;
1514 	case SP_FILEMARKS:
1515 		if (st->flags & ST_EIO_PENDING) {
1516 			if (number > 0) {
1517 				/* pretend we just discovered the error */
1518 				st->flags &= ~ST_EIO_PENDING;
1519 				return EIO;
1520 			} else if (number < 0) {
1521 				/* back away from the error */
1522 				st->flags &= ~ST_EIO_PENDING;
1523 			}
1524 		}
1525 		if (st->flags & ST_AT_FILEMARK) {
1526 			st->flags &= ~ST_AT_FILEMARK;
1527 			number--;
1528 		}
1529 		if ((st->flags & ST_BLANK_READ) && (number < 0)) {
1530 			/* back away from unwritten tape */
1531 			st->flags &= ~ST_BLANK_READ;
1532 			number++;	/* XXX dubious */
1533 		}
1534 		break;
1535 	case SP_EOM:
1536 		if (st->flags & ST_EIO_PENDING) {
1537 			/* pretend we just discovered the error */
1538 			st->flags &= ~ST_EIO_PENDING;
1539 			return EIO;
1540 		}
1541 		if (st->flags & ST_AT_FILEMARK)
1542 			st->flags &= ~ST_AT_FILEMARK;
1543 		break;
1544 	}
1545 	if (number == 0)
1546 		return 0;
1547 
1548 	bzero(&cmd, sizeof(cmd));
1549 	cmd.opcode = SPACE;
1550 	cmd.byte2 = what;
1551 	_lto3b(number, cmd.number);
1552 
1553 	return scsi_scsi_cmd(st->sc_link, (struct scsi_generic *) &cmd,
1554 	    sizeof(cmd), 0, 0, 0, 900000, NULL, flags);
1555 }
1556 
1557 /*
1558  * write N filemarks
1559  */
1560 int
1561 st_write_filemarks(st, number, flags)
1562 	struct st_softc *st;
1563 	int flags;
1564 	int number;
1565 {
1566 	struct scsi_write_filemarks cmd;
1567 
1568 	/*
1569 	 * It's hard to write a negative number of file marks.
1570 	 * Don't try.
1571 	 */
1572 	if (number < 0)
1573 		return EINVAL;
1574 	switch (number) {
1575 	case 0:		/* really a command to sync the drive's buffers */
1576 		break;
1577 	case 1:
1578 		if (st->flags & ST_FM_WRITTEN)	/* already have one down */
1579 			st->flags &= ~ST_WRITTEN;
1580 		else
1581 			st->flags |= ST_FM_WRITTEN;
1582 		st->flags &= ~ST_PER_ACTION;
1583 		break;
1584 	default:
1585 		st->flags &= ~(ST_PER_ACTION | ST_WRITTEN);
1586 	}
1587 
1588 	bzero(&cmd, sizeof(cmd));
1589 	cmd.opcode = WRITE_FILEMARKS;
1590 	_lto3b(number, cmd.number);
1591 
1592 	return scsi_scsi_cmd(st->sc_link, (struct scsi_generic *) &cmd,
1593 	    sizeof(cmd), 0, 0, 0, 100000, NULL, flags);
1594 }
1595 
1596 /*
1597  * Make sure the right number of file marks is on tape if the
1598  * tape has been written.  If the position argument is true,
1599  * leave the tape positioned where it was originally.
1600  *
1601  * nmarks returns the number of marks to skip (or, if position
1602  * true, which were skipped) to get back original position.
1603  */
1604 int
1605 st_check_eod(st, position, nmarks, flags)
1606 	struct st_softc *st;
1607 	boolean position;
1608 	int *nmarks;
1609 	int flags;
1610 {
1611 	int error;
1612 
1613 	switch (st->flags & (ST_WRITTEN | ST_FM_WRITTEN | ST_2FM_AT_EOD)) {
1614 	default:
1615 		*nmarks = 0;
1616 		return 0;
1617 	case ST_WRITTEN:
1618 	case ST_WRITTEN | ST_FM_WRITTEN | ST_2FM_AT_EOD:
1619 		*nmarks = 1;
1620 		break;
1621 	case ST_WRITTEN | ST_2FM_AT_EOD:
1622 		*nmarks = 2;
1623 	}
1624 	error = st_write_filemarks(st, *nmarks, flags);
1625 	if (position && !error)
1626 		error = st_space(st, -*nmarks, SP_FILEMARKS, flags);
1627 	return error;
1628 }
1629 
1630 /*
1631  * load/unload/retension
1632  */
1633 int
1634 st_load(st, type, flags)
1635 	struct st_softc *st;
1636 	u_int type;
1637 	int flags;
1638 {
1639 	struct scsi_load cmd;
1640 
1641 	if (type != LD_LOAD) {
1642 		int error;
1643 		int nmarks;
1644 
1645 		error = st_check_eod(st, FALSE, &nmarks, flags);
1646 		if (error)
1647 			return error;
1648 	}
1649 	if (st->quirks & ST_Q_IGNORE_LOADS)
1650 		return 0;
1651 
1652 	bzero(&cmd, sizeof(cmd));
1653 	cmd.opcode = LOAD;
1654 	cmd.how = type;
1655 
1656 	return scsi_scsi_cmd(st->sc_link, (struct scsi_generic *) &cmd,
1657 	    sizeof(cmd), 0, 0, ST_RETRIES, 300000, NULL, flags);
1658 }
1659 
1660 /*
1661  *  Rewind the device
1662  */
1663 int
1664 st_rewind(st, immediate, flags)
1665 	struct st_softc *st;
1666 	u_int immediate;
1667 	int flags;
1668 {
1669 	struct scsi_rewind cmd;
1670 	int error;
1671 	int nmarks;
1672 
1673 	error = st_check_eod(st, FALSE, &nmarks, flags);
1674 	if (error)
1675 		return error;
1676 	st->flags &= ~ST_PER_ACTION;
1677 
1678 	bzero(&cmd, sizeof(cmd));
1679 	cmd.opcode = REWIND;
1680 	cmd.byte2 = immediate;
1681 
1682 	return scsi_scsi_cmd(st->sc_link, (struct scsi_generic *) &cmd,
1683 	    sizeof(cmd), 0, 0, ST_RETRIES, immediate ? 5000 : 300000, NULL,
1684 	    flags);
1685 }
1686 
1687 /*
1688  * Look at the returned sense and act on the error and detirmine
1689  * The unix error number to pass back... (0 = report no error)
1690  *                            (-1 = continue processing)
1691  */
1692 int
1693 st_interpret_sense(xs)
1694 	struct scsi_xfer *xs;
1695 {
1696 	struct scsi_link *sc_link = xs->sc_link;
1697 	struct scsi_sense_data *sense = &xs->sense;
1698 	struct buf *bp = xs->bp;
1699 	struct st_softc *st = sc_link->device_softc;
1700 	u_int8_t key;
1701 	int32_t info;
1702 
1703 	/*
1704 	 * Get the sense fields and work out what code
1705 	 */
1706 	if (sense->error_code & SSD_ERRCODE_VALID)
1707 		info = _4btol(sense->info);
1708 	else
1709 		info = xs->datalen;	/* bad choice if fixed blocks */
1710 	if ((sense->error_code & SSD_ERRCODE) != 0x70)
1711 		return -1;	/* let the generic code handle it */
1712 	if (st->flags & ST_FIXEDBLOCKS) {
1713 		xs->resid = info * st->blksize;
1714 		if (sense->flags & SSD_EOM) {
1715 			st->flags |= ST_EIO_PENDING;
1716 			if (bp)
1717 				bp->b_resid = xs->resid;
1718 		}
1719 		if (sense->flags & SSD_FILEMARK) {
1720 			st->flags |= ST_AT_FILEMARK;
1721 			if (bp)
1722 				bp->b_resid = xs->resid;
1723 		}
1724 		if (sense->flags & SSD_ILI) {
1725 			st->flags |= ST_EIO_PENDING;
1726 			if (bp)
1727 				bp->b_resid = xs->resid;
1728 			if (sense->error_code & SSD_ERRCODE_VALID &&
1729 			    (xs->flags & SCSI_SILENT) == 0)
1730 				printf("%s: block wrong size, %d blocks residual\n",
1731 				    st->sc_dev.dv_xname, info);
1732 
1733 			/*
1734 			 * This quirk code helps the drive read
1735 			 * the first tape block, regardless of
1736 			 * format.  That is required for these
1737 			 * drives to return proper MODE SENSE
1738 			 * information.
1739 			 */
1740 			if ((st->quirks & ST_Q_SENSE_HELP) &&
1741 			    !(sc_link->flags & SDEV_MEDIA_LOADED))
1742 				st->blksize -= 512;
1743 		}
1744 		/*
1745 		 * If no data was tranfered, do it immediatly
1746 		 */
1747 		if (xs->resid >= xs->datalen) {
1748 			if (st->flags & ST_EIO_PENDING)
1749 				return EIO;
1750 			if (st->flags & ST_AT_FILEMARK) {
1751 				if (bp)
1752 					bp->b_resid = xs->resid;
1753 				return 0;
1754 			}
1755 		}
1756 	} else {		/* must be variable mode */
1757 		xs->resid = xs->datalen;	/* to be sure */
1758 		if (sense->flags & SSD_EOM)
1759 			return EIO;
1760 		if (sense->flags & SSD_FILEMARK) {
1761 			if (bp)
1762 				bp->b_resid = bp->b_bcount;
1763 			return 0;
1764 		}
1765 		if (sense->flags & SSD_ILI) {
1766 			if (info < 0) {
1767 				/*
1768 				 * the record was bigger than the read
1769 				 */
1770 				if ((xs->flags & SCSI_SILENT) == 0)
1771 					printf("%s: %d-byte record too big\n",
1772 					    st->sc_dev.dv_xname,
1773 					    xs->datalen - info);
1774 				return EIO;
1775 			}
1776 			xs->resid = info;
1777 			if (bp)
1778 				bp->b_resid = info;
1779 		}
1780 	}
1781 	key = sense->flags & SSD_KEY;
1782 
1783 	if (key == 0x8) {
1784 		/*
1785 		 * This quirk code helps the drive read the
1786 		 * first tape block, regardless of format.  That
1787 		 * is required for these drives to return proper
1788 		 * MODE SENSE information.
1789 		 */
1790 		if ((st->quirks & ST_Q_SENSE_HELP) &&
1791 		    !(sc_link->flags & SDEV_MEDIA_LOADED)) {
1792 			/* still starting */
1793 			st->blksize -= 512;
1794 		} else if (!(st->flags & (ST_2FM_AT_EOD | ST_BLANK_READ))) {
1795 			st->flags |= ST_BLANK_READ;
1796 			xs->resid = xs->datalen;
1797 			if (bp) {
1798 				bp->b_resid = xs->resid;
1799 				/* return an EOF */
1800 			}
1801 			return 0;
1802 		}
1803 	}
1804 	return -1;		/* let the default/generic handler handle it */
1805 }
1806 
1807 /*
1808  * The quirk here is that the drive returns some value to st_mode_sense
1809  * incorrectly until the tape has actually passed by the head.
1810  *
1811  * The method is to set the drive to large fixed-block state (user-specified
1812  * density and 1024-byte blocks), then read and rewind to get it to sense the
1813  * tape.  If that doesn't work, try 512-byte fixed blocks.  If that doesn't
1814  * work, as a last resort, try variable- length blocks.  The result will be
1815  * the ability to do an accurate st_mode_sense.
1816  *
1817  * We know we can do a rewind because we just did a load, which implies rewind.
1818  * Rewind seems preferable to space backward if we have a virgin tape.
1819  *
1820  * The rest of the code for this quirk is in ILI processing and BLANK CHECK
1821  * error processing, both part of st_interpret_sense.
1822  */
1823 int
1824 st_touch_tape(st)
1825 	struct st_softc *st;
1826 {
1827 	char *buf;
1828 	int readsize;
1829 	int error;
1830 
1831 	buf = malloc(1024, M_TEMP, M_NOWAIT);
1832 	if (!buf)
1833 		return ENOMEM;
1834 
1835 	if ((error = st_mode_sense(st, 0)) != 0)
1836 		goto bad;
1837 	st->blksize = 1024;
1838 	do {
1839 		switch (st->blksize) {
1840 		case 512:
1841 		case 1024:
1842 			readsize = st->blksize;
1843 			st->flags |= ST_FIXEDBLOCKS;
1844 			break;
1845 		default:
1846 			readsize = 1;
1847 			st->flags &= ~ST_FIXEDBLOCKS;
1848 		}
1849 		if ((error = st_mode_select(st, 0)) != 0)
1850 			goto bad;
1851 		st_read(st, buf, readsize, SCSI_SILENT);	/* XXX */
1852 		if ((error = st_rewind(st, 0, 0)) != 0) {
1853 bad:			free(buf, M_TEMP);
1854 			return error;
1855 		}
1856 	} while (readsize != 1 && readsize > st->blksize);
1857 
1858 	free(buf, M_TEMP);
1859 	return 0;
1860 }
1861 
1862 int
1863 stdump(dev, blkno, va, size)
1864 	dev_t dev;
1865 	daddr_t blkno;
1866 	caddr_t va;
1867 	size_t size;
1868 {
1869 
1870 	/* Not implemented. */
1871 	return ENXIO;
1872 }
1873