xref: /openbsd/sys/scsi/st.c (revision 274d7c50)
1 /*	$OpenBSD: st.c,v 1.171 2019/11/26 20:48:03 krw Exp $	*/
2 /*	$NetBSD: st.c,v 1.71 1997/02/21 23:03:49 thorpej Exp $	*/
3 
4 /*
5  * Copyright (c) 1994 Charles Hannum.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. All advertising materials mentioning features or use of this software
16  *    must display the following acknowledgement:
17  *	This product includes software developed by Charles Hannum.
18  * 4. The name of the author may not be used to endorse or promote products
19  *    derived from this software without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
26  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
30  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31  */
32 
33 /*
34  * Originally written by Julian Elischer (julian@tfs.com)
35  * for TRW Financial Systems for use under the MACH(2.5) operating system.
36  *
37  * TRW Financial Systems, in accordance with their agreement with Carnegie
38  * Mellon University, makes this software available to CMU to distribute
39  * or use in any manner that they see fit as long as this message is kept with
40  * the software. For this reason TFS also grants any other persons or
41  * organisations permission to use or modify this software.
42  *
43  * TFS supplies this software to be publicly redistributed
44  * on the understanding that TFS is not responsible for the correct
45  * functioning of this software in any circumstances.
46  *
47  * Ported to run under 386BSD by Julian Elischer (julian@tfs.com) Sept 1992
48  * major changes by Julian Elischer (julian@jules.dialix.oz.au) May 1993
49  */
50 
51 /*
52  * To do:
53  * work out some better way of guessing what a good timeout is going
54  * to be depending on whether we expect to retension or not.
55  */
56 
57 #include <sys/param.h>
58 #include <sys/systm.h>
59 #include <sys/timeout.h>
60 #include <sys/fcntl.h>
61 #include <sys/errno.h>
62 #include <sys/ioctl.h>
63 #include <sys/stat.h>
64 #include <sys/pool.h>
65 #include <sys/buf.h>
66 #include <sys/mtio.h>
67 #include <sys/device.h>
68 #include <sys/conf.h>
69 #include <sys/vnode.h>
70 
71 #include <scsi/scsi_all.h>
72 #include <scsi/scsi_tape.h>
73 #include <scsi/scsiconf.h>
74 
75 /* Defines for device specific stuff */
76 #define DEF_FIXED_BSIZE  512
77 
78 #define STMODE(z)	( minor(z)	 & 0x03)
79 #define STUNIT(z)	((minor(z) >> 4)       )
80 
81 #define STMINOR(unit, mode)	(((unit) << 4) + (mode))
82 #define MAXSTMODES	16	/* Old max retained so minor's don't change. */
83 
84 #define	ST_IO_TIME	(3 * 60 * 1000)		/* 3 minutes */
85 #define	ST_CTL_TIME	(30 * 1000)		/* 30 seconds */
86 #define	ST_SPC_TIME	(4 * 60 * 60 * 1000)	/* 4 hours */
87 
88 /*
89  * Maximum density code allowed in SCSI spec (SSC2R08f, Section 8.3).
90  */
91 #define SCSI_MAX_DENSITY_CODE		0xff
92 
93 /*
94  * Define various devices that we know mis-behave in some way,
95  * and note how they are bad, so we can correct for them
96  */
97 struct mode {
98 	int blksize;
99 	u_int8_t density;
100 };
101 
102 struct quirkdata {
103 	u_int quirks;
104 #define	ST_Q_SENSE_HELP		0x0001	/* must do READ for good MODE SENSE */
105 #define	ST_Q_IGNORE_LOADS	0x0002
106 #define	ST_Q_UNIMODAL		0x0004	/* unimode drive rejects mode select */
107 	struct mode mode;
108 };
109 
110 struct st_quirk_inquiry_pattern {
111 	struct scsi_inquiry_pattern pattern;
112 	struct quirkdata quirkdata;
113 };
114 
115 const struct st_quirk_inquiry_pattern st_quirk_patterns[] = {
116 	{{T_SEQUENTIAL, T_REMOV,
117 		 "        ", "                ", "    "}, {0,
118 							   {512, 0}}},
119  	{{T_SEQUENTIAL, T_REMOV,
120 		 "TANDBERG", " TDC 3800       ", ""},     {0,
121 							   {512, 0}}},
122 	{{T_SEQUENTIAL, T_REMOV,
123 		 "ARCHIVE ", "VIPER 2525 25462", ""},     {ST_Q_SENSE_HELP,
124 							   {0, 0}}},
125 	{{T_SEQUENTIAL, T_REMOV,
126 		 "SANKYO  ", "CP525           ", ""},     {0,
127 							   {512, 0}}},
128 	{{T_SEQUENTIAL, T_REMOV,
129 		 "ANRITSU ", "DMT780          ", ""},     {0,
130 							   {512, 0}}},
131 	{{T_SEQUENTIAL, T_REMOV,
132 		 "ARCHIVE ", "VIPER 150  21531", ""},     {ST_Q_SENSE_HELP,
133 							   {0, 0}}},
134 	{{T_SEQUENTIAL, T_REMOV,
135 		 "WANGTEK ", "5099ES SCSI",	 ""},     {0,
136 							   {512, 0}}},
137 	{{T_SEQUENTIAL, T_REMOV,
138 		 "WANGTEK ", "5150ES SCSI",	 ""},     {0,
139 							   {512, 0}}},
140 	{{T_SEQUENTIAL, T_REMOV,
141 		 "HP      ", "T4000s          ", ""},     {ST_Q_UNIMODAL,
142 							   {0, QIC_3095}}},
143 	{{T_SEQUENTIAL, T_REMOV,
144 		 "WANGTEK ", "5150ES SCSI FA15", "01 A"}, {ST_Q_IGNORE_LOADS,
145 							   {0, 0}}},
146 	{{T_SEQUENTIAL, T_REMOV,
147 		 "TEAC    ", "MT-2ST/N50      ", ""},     {ST_Q_IGNORE_LOADS,
148 							   {0, 0}}},
149 };
150 
151 #define NOEJECT 0
152 #define EJECT 1
153 
154 #define NOREWIND 0
155 #define DOREWIND 1
156 
157 struct st_softc {
158 	struct device sc_dev;
159 
160 	int flags;
161 #define	ST_INFO_VALID		0x00000001
162 #define	ST_WRITTEN		0x00000004
163 #define	ST_FIXEDBLOCKS		0x00000008
164 #define	ST_AT_FILEMARK		0x00000010
165 #define	ST_EIO_PENDING		0x00000020
166 #define	ST_EOM_PENDING  	0x00000040
167 #define	ST_EOD_DETECTED		0x00000080
168 #define	ST_FM_WRITTEN		0x00000100
169 #define	ST_BLANK_READ		0x00000200
170 #define	ST_2FM_AT_EOD		0x00000400
171 #define	ST_MOUNTED		0x00000800
172 #define	ST_DONTBUFFER		0x00001000
173 #define	ST_WAITING		0x00002000
174 #define	ST_DYING		0x00004000
175 #define	ST_BOD_DETECTED		0x00008000
176 #define	ST_MODE_DENSITY		0x00010000
177 #define	ST_MODE_BLKSIZE		0x00040000
178 
179 	u_int quirks;		/* quirks for the open mode           */
180 	int blksize;		/* blksize we are using               */
181 	u_int8_t density;	/* present density                    */
182 	short mt_resid;		/* last (short) resid                 */
183 	short mt_erreg;		/* last error (sense key) seen        */
184 
185 	struct scsi_link *sc_link;	/* our link to the adpter etc.        */
186 
187 	int blkmin;		/* min blk size                       */
188 	int blkmax;		/* max blk size                       */
189 
190 	u_int32_t media_blksize;	/* 0 if not ST_FIXEDBLOCKS            */
191 	u_int32_t media_density;	/* this is what it said when asked    */
192 	int media_fileno;		/* relative to BOT. -1 means unknown. */
193 	int media_blkno;		/* relative to BOF. -1 means unknown. */
194 	int media_eom;			/* relative to BOT. -1 means unknown. */
195 
196 	struct mode mode;
197 	struct bufq sc_bufq;
198 	struct timeout sc_timeout;
199 	struct scsi_xshandler sc_xsh;
200 };
201 
202 
203 int	stmatch(struct device *, void *, void *);
204 void	stattach(struct device *, struct device *, void *);
205 int	stactivate(struct device *, int);
206 int	stdetach(struct device *, int);
207 void	stminphys(struct buf *);
208 void	ststart(struct scsi_xfer *);
209 
210 int	st_mount_tape(struct st_softc *, int);
211 void	st_unmount(struct st_softc *, int, int);
212 int	st_decide_mode(struct st_softc *, int);
213 void	st_buf_done(struct scsi_xfer *);
214 int	st_read(struct st_softc *, char *, int, int);
215 int	st_read_block_limits(struct st_softc *, int);
216 int	st_mode_sense(struct st_softc *, int);
217 int	st_mode_select(struct st_softc *, int);
218 int	st_space(struct st_softc *, int, u_int, int);
219 int	st_write_filemarks(struct st_softc *, int, int);
220 int	st_check_eod(struct st_softc *, int, int *, int);
221 int	st_load(struct st_softc *, u_int, int);
222 int	st_rewind(struct st_softc *, u_int, int);
223 int	st_interpret_sense(struct scsi_xfer *);
224 int	st_touch_tape(struct st_softc *);
225 int	st_erase(struct st_softc *, int, int);
226 
227 struct cfattach st_ca = {
228 	sizeof(struct st_softc), stmatch, stattach,
229 	stdetach, stactivate
230 };
231 
232 struct cfdriver st_cd = {
233 	NULL, "st", DV_TAPE
234 };
235 
236 #define	ST_PER_ACTION	(ST_AT_FILEMARK | ST_EIO_PENDING | ST_EOM_PENDING | \
237 			 ST_BLANK_READ)
238 
239 #define stlookup(unit) (struct st_softc *)device_lookup(&st_cd, (unit))
240 
241 const struct scsi_inquiry_pattern st_patterns[] = {
242 	{T_SEQUENTIAL, T_REMOV,
243 	 "",         "",                 ""},
244 };
245 
246 int
247 stmatch(struct device *parent, void *match, void *aux)
248 {
249 	struct scsi_attach_args *sa = aux;
250 	int priority;
251 
252 	(void)scsi_inqmatch(sa->sa_inqbuf,
253 	    st_patterns, nitems(st_patterns),
254 	    sizeof(st_patterns[0]), &priority);
255 	return priority;
256 }
257 
258 /*
259  * The routine called by the low level scsi routine when it discovers
260  * a device suitable for this driver.
261  */
262 void
263 stattach(struct device *parent, struct device *self, void *aux)
264 {
265 	const struct st_quirk_inquiry_pattern *finger;
266 	struct st_softc *st = (void *)self;
267 	struct scsi_attach_args *sa = aux;
268 	struct scsi_link *link = sa->sa_sc_link;
269 	int priority;
270 
271 	SC_DEBUG(link, SDEV_DB2, ("stattach:\n"));
272 
273 	/*
274 	 * Store information needed to contact our base driver
275 	 */
276 	st->sc_link = link;
277 	link->interpret_sense = st_interpret_sense;
278 	link->device_softc = st;
279 
280 	/* Get any quirks and mode information. */
281 	finger = (const struct st_quirk_inquiry_pattern *)scsi_inqmatch(
282 	    &link->inqdata,
283 	    st_quirk_patterns,
284 	    nitems(st_quirk_patterns),
285 	    sizeof(st_quirk_patterns[0]), &priority);
286 	if (finger != NULL) {
287 		st->quirks = finger->quirkdata.quirks;
288 		st->mode = finger->quirkdata.mode;
289 		CLR(st->flags, ST_MODE_BLKSIZE | ST_MODE_DENSITY);
290 		if (st->mode.blksize != 0)
291 			SET(st->flags, ST_MODE_BLKSIZE);
292 		if (st->mode.density != 0)
293 			SET(st->flags, ST_MODE_DENSITY);
294 	}
295 	printf("\n");
296 
297 	scsi_xsh_set(&st->sc_xsh, link, ststart);
298 	timeout_set(&st->sc_timeout, (void (*)(void *))scsi_xsh_set,
299 	    &st->sc_xsh);
300 
301 	/* Set up the buf queue for this device. */
302 	bufq_init(&st->sc_bufq, BUFQ_FIFO);
303 
304 	/* Start up with media position unknown. */
305 	st->media_fileno = -1;
306 	st->media_blkno = -1;
307 	st->media_eom = -1;
308 
309 	/*
310 	 * Reset the media loaded flag, sometimes the data
311 	 * acquired at boot time is not quite accurate.  This
312 	 * will be checked again at the first open.
313 	 */
314 	CLR(link->flags, SDEV_MEDIA_LOADED);
315 }
316 
317 int
318 stactivate(struct device *self, int act)
319 {
320 	struct st_softc *st = (struct st_softc *)self;
321 
322 	switch (act) {
323 	case DVACT_DEACTIVATE:
324 		SET(st->flags, ST_DYING);
325 		scsi_xsh_del(&st->sc_xsh);
326 		break;
327 	}
328 
329 	return 0;
330 }
331 
332 int
333 stdetach(struct device *self, int flags)
334 {
335 	struct st_softc *st = (struct st_softc *)self;
336 	int cmaj, mn;
337 
338 	bufq_drain(&st->sc_bufq);
339 
340 	/* Locate the lowest minor number to be detached. */
341 	mn = STMINOR(self->dv_unit, 0);
342 
343 	for (cmaj = 0; cmaj < nchrdev; cmaj++)
344 		if (cdevsw[cmaj].d_open == stopen)
345 			vdevgone(cmaj, mn, mn + MAXSTMODES - 1, VCHR);
346 
347 	bufq_destroy(&st->sc_bufq);
348 
349 	return 0;
350 }
351 
352 /*
353  * open the device.
354  */
355 int
356 stopen(dev_t dev, int flags, int fmt, struct proc *p)
357 {
358 	struct scsi_link *link;
359 	struct st_softc *st;
360 	int error = 0;
361 
362 	st = stlookup(STUNIT(dev));
363 	if (st == NULL)
364 		return ENXIO;
365 	if (ISSET(st->flags, ST_DYING)) {
366 		error = ENXIO;
367 		goto done;
368 	}
369 	link = st->sc_link;
370 
371 	if (ISSET(flags, FWRITE) && ISSET(link->flags, SDEV_READONLY)) {
372 		error = EACCES;
373 		goto done;
374 	}
375 
376 	SC_DEBUG(link, SDEV_DB1, ("open: dev=0x%x (unit %d (of %d))\n", dev,
377 	    STUNIT(dev), st_cd.cd_ndevs));
378 
379 	/*
380 	 * Tape is an exclusive media. Only one open at a time.
381 	 */
382 	if (ISSET(link->flags, SDEV_OPEN)) {
383 		SC_DEBUG(link, SDEV_DB4, ("already open\n"));
384 		error = EBUSY;
385 		goto done;
386 	}
387 
388 	/* Use st_interpret_sense() now. */
389 	SET(link->flags, SDEV_OPEN);
390 
391 	/*
392 	 * Check the unit status. This clears any outstanding errors and
393 	 * will ensure that media is present.
394 	 */
395 	error = scsi_test_unit_ready(link, TEST_READY_RETRIES,
396 	    SCSI_SILENT | SCSI_IGNORE_MEDIA_CHANGE |
397 	    SCSI_IGNORE_ILLEGAL_REQUEST);
398 
399 	/*
400 	 * Terminate any exising mount session if there is no media.
401 	 */
402 	if (!ISSET(link->flags, SDEV_MEDIA_LOADED))
403 		st_unmount(st, NOEJECT, DOREWIND);
404 
405 	if (error != 0) {
406 		CLR(link->flags, SDEV_OPEN);
407 		goto done;
408 	}
409 
410 	error = st_mount_tape(st, flags);
411 	if (error != 0) {
412 		CLR(link->flags, SDEV_OPEN);
413 		goto done;
414 	}
415 
416 	/*
417 	 * Make sure that a tape opened in write-only mode will have
418 	 * file marks written on it when closed, even if not written to.
419 	 * This is for SUN compatibility
420 	 */
421 	if ((flags & O_ACCMODE) == FWRITE)
422 		SET(st->flags, ST_WRITTEN);
423 
424 done:
425 	SC_DEBUG(link, SDEV_DB2, ("open complete\n"));
426 	device_unref(&st->sc_dev);
427 	return error;
428 }
429 
430 /*
431  * close the device.. only called if we are the LAST
432  * occurrence of an open device
433  */
434 int
435 stclose(dev_t dev, int flags, int mode, struct proc *p)
436 {
437 	struct scsi_link *link;
438 	struct st_softc *st;
439 	int error = 0;
440 
441 	st = stlookup(STUNIT(dev));
442 	if (st == NULL)
443 		return ENXIO;
444 	if (ISSET(st->flags, ST_DYING)) {
445 		error = ENXIO;
446 		goto done;
447 	}
448 	link = st->sc_link;
449 
450 	SC_DEBUG(link, SDEV_DB1, ("closing\n"));
451 
452 	if (ISSET(st->flags, ST_WRITTEN) && !ISSET(st->flags, ST_FM_WRITTEN))
453 		st_write_filemarks(st, 1, 0);
454 
455 	switch (STMODE(dev)) {
456 	case 0:		/* /dev/rstN */
457 		st_unmount(st, NOEJECT, DOREWIND);
458 		break;
459 	case 1:		/* /dev/nrstN */
460 		st_unmount(st, NOEJECT, NOREWIND);
461 		break;
462 	case 2:		/* /dev/erstN */
463 		st_unmount(st, EJECT, DOREWIND);
464 		break;
465 	case 3:		/* /dev/enrstN */
466 		st_unmount(st, EJECT, NOREWIND);
467 		break;
468 	}
469 	CLR(link->flags, SDEV_OPEN);
470 	timeout_del(&st->sc_timeout);
471 	scsi_xsh_del(&st->sc_xsh);
472 
473 done:
474 	device_unref(&st->sc_dev);
475 	return error;
476 }
477 
478 /*
479  * Start a new mount session if needed.
480  */
481 int
482 st_mount_tape(struct st_softc *st, int flags)
483 {
484 	struct scsi_link *link = st->sc_link;
485 	int error = 0;
486 
487 	if (ISSET(st->flags, ST_MOUNTED))
488 		return 0;
489 
490 	SC_DEBUG(link, SDEV_DB1, ("mounting\n"));
491 
492 	/*
493 	 * Assume the media is new and give it a chance to
494 	 * to do a 'load' instruction.
495 	 */
496 	if ((error = st_load(st, LD_LOAD, 0)) != 0)
497 		goto done;
498 
499 	/*
500 	 * Throw another dummy instruction to catch
501 	 * 'Unit attention' errors. Some drives appear to give
502 	 * these after doing a Load instruction.
503 	 * (noteably some DAT drives)
504 	 */
505 	/* XXX */
506 	scsi_test_unit_ready(link, TEST_READY_RETRIES, SCSI_SILENT);
507 
508 	/*
509 	 * Some devices can't tell you much until they have been
510 	 * asked to look at the media. This quirk does this.
511 	 */
512 	if (ISSET(st->quirks, ST_Q_SENSE_HELP))
513 		if ((error = st_touch_tape(st)) != 0)
514 			return error;
515 	/*
516 	 * Load the physical device parameters
517 	 * loads: blkmin, blkmax
518 	 */
519 	if (!ISSET(link->flags, SDEV_ATAPI) &&
520 	    (error = st_read_block_limits(st, 0)) != 0)
521 		goto done;
522 
523 	/*
524 	 * Load the media dependent parameters
525 	 * includes: media_blksize,media_density
526 	 * As we have a tape in, it should be reflected here.
527 	 * If not you may need the "quirk" above.
528 	 */
529 	if ((error = st_mode_sense(st, 0)) != 0)
530 		goto done;
531 
532 	/*
533 	 * If we have gained a permanent density from somewhere,
534 	 * then use it in preference to the one supplied by
535 	 * default by the driver.
536 	 */
537 	if (ISSET(st->flags, ST_MODE_DENSITY))
538 		st->density = st->mode.density;
539 	else
540 		st->density = st->media_density;
541 	/*
542 	 * If we have gained a permanent blocksize
543 	 * then use it in preference to the one supplied by
544 	 * default by the driver.
545 	 */
546 	CLR(st->flags, ST_FIXEDBLOCKS);
547 	if (ISSET(st->flags, ST_MODE_BLKSIZE)) {
548 		st->blksize = st->mode.blksize;
549 		if (st->blksize)
550 			SET(st->flags, ST_FIXEDBLOCKS);
551 	} else {
552 		if ((error = st_decide_mode(st, 0)) != 0)
553 			goto done;
554 	}
555 	if ((error = st_mode_select(st, 0)) != 0) {
556 		printf("%s: cannot set selected mode\n", st->sc_dev.dv_xname);
557 		goto done;
558 	}
559 	scsi_prevent(link, PR_PREVENT,
560 	    SCSI_IGNORE_ILLEGAL_REQUEST | SCSI_IGNORE_NOT_READY);
561 	SET(st->flags, ST_MOUNTED);
562 	SET(link->flags, SDEV_MEDIA_LOADED);	/* move earlier? */
563 	st->media_fileno = 0;
564 	st->media_blkno = 0;
565 	st->media_eom = -1;
566 
567 done:
568 	return error;
569 }
570 
571 /*
572  * End the present mount session.
573  * Rewind, and optionally eject the tape.
574  * Reset various flags to indicate that all new
575  * operations require another mount operation
576  */
577 void
578 st_unmount(struct st_softc *st, int eject, int rewind)
579 {
580 	struct scsi_link *link = st->sc_link;
581 	int nmarks;
582 
583 	if (eject == NOEJECT && rewind == NOREWIND) {
584 		if (ISSET(link->flags, SDEV_MEDIA_LOADED))
585 			return;
586 	}
587 
588 	st->media_fileno = -1;
589 	st->media_blkno = -1;
590 
591 	if (!ISSET(st->flags, ST_MOUNTED))
592 		return;
593 	SC_DEBUG(link, SDEV_DB1, ("unmounting\n"));
594 	st_check_eod(st, 0, &nmarks, SCSI_IGNORE_NOT_READY);
595 	if (rewind == DOREWIND)
596 		st_rewind(st, 0, SCSI_IGNORE_NOT_READY);
597 	scsi_prevent(link, PR_ALLOW,
598 	    SCSI_IGNORE_ILLEGAL_REQUEST | SCSI_IGNORE_NOT_READY);
599 	if (eject == EJECT)
600 		st_load(st, LD_UNLOAD, SCSI_IGNORE_NOT_READY);
601 	CLR(st->flags, ST_MOUNTED);
602 	CLR(link->flags, SDEV_MEDIA_LOADED);
603 }
604 
605 /*
606  * Given all we know about the device, media, mode, 'quirks' and
607  * initial operation, make a decision as to how we should be set
608  * to run (regarding blocking and EOD marks)
609  */
610 int
611 st_decide_mode(struct st_softc *st, int first_read)
612 {
613 	struct scsi_link *link = st->sc_link;
614 
615 	SC_DEBUG(link, SDEV_DB2, ("starting block mode decision\n"));
616 
617 	/* ATAPI tapes are always fixed blocksize. */
618 	if (ISSET(link->flags, SDEV_ATAPI)) {
619 		SET(st->flags, ST_FIXEDBLOCKS);
620 		if (st->media_blksize > 0)
621 			st->blksize = st->media_blksize;
622 		else
623 			st->blksize = DEF_FIXED_BSIZE;
624 		goto done;
625 	}
626 
627 	/*
628 	 * If the drive can only handle fixed-length blocks and only at
629 	 * one size, perhaps we should just do that.
630 	 */
631 	if (st->blkmin && (st->blkmin == st->blkmax)) {
632 		SET(st->flags, ST_FIXEDBLOCKS);
633 		st->blksize = st->blkmin;
634 		SC_DEBUG(link, SDEV_DB3,
635 		    ("blkmin == blkmax of %d\n", st->blkmin));
636 		goto done;
637 	}
638 	/*
639 	 * If the tape density mandates (or even suggests) use of fixed
640 	 * or variable-length blocks, comply.
641 	 */
642 	switch (st->density) {
643 	case HALFINCH_800:
644 	case HALFINCH_1600:
645 	case HALFINCH_6250:
646 	case DDS:
647 		CLR(st->flags, ST_FIXEDBLOCKS);
648 		st->blksize = 0;
649 		SC_DEBUG(link, SDEV_DB3, ("density specified variable\n"));
650 		goto done;
651 	case QIC_11:
652 	case QIC_24:
653 	case QIC_120:
654 	case QIC_150:
655 	case QIC_525:
656 	case QIC_1320:
657 		SET(st->flags, ST_FIXEDBLOCKS);
658 		if (st->media_blksize > 0)
659 			st->blksize = st->media_blksize;
660 		else
661 			st->blksize = DEF_FIXED_BSIZE;
662 		SC_DEBUG(link, SDEV_DB3, ("density specified fixed\n"));
663 		goto done;
664 	}
665 	/*
666 	 * If we're about to read the tape, perhaps we should choose
667 	 * fixed or variable-length blocks and block size according to
668 	 * what the drive found on the tape.
669 	 */
670 	if (first_read) {
671 		if (st->media_blksize > 0)
672 			SET(st->flags, ST_FIXEDBLOCKS);
673 		else
674 			CLR(st->flags, ST_FIXEDBLOCKS);
675 		st->blksize = st->media_blksize;
676 		SC_DEBUG(link, SDEV_DB3,
677 		    ("Used media_blksize of %d\n", st->media_blksize));
678 		goto done;
679 	}
680 	/*
681 	 * We're getting no hints from any direction.  Choose variable-
682 	 * length blocks arbitrarily.
683 	 */
684 	CLR(st->flags, ST_FIXEDBLOCKS);
685 	st->blksize = 0;
686 	SC_DEBUG(link, SDEV_DB3,
687 	    ("Give up and default to variable mode\n"));
688 
689 done:
690 	/*
691 	 * Decide whether or not to write two file marks to signify end-
692 	 * of-data.  Make the decision as a function of density.  If
693 	 * the decision is not to use a second file mark, the SCSI BLANK
694 	 * CHECK condition code will be recognized as end-of-data when
695 	 * first read.
696 	 * (I think this should be a by-product of fixed/variable..julian)
697 	 */
698 	switch (st->density) {
699 /*      case 8 mm:   What is the SCSI density code for 8 mm, anyway? */
700 	case QIC_11:
701 	case QIC_24:
702 	case QIC_120:
703 	case QIC_150:
704 	case QIC_525:
705 	case QIC_1320:
706 		CLR(st->flags, ST_2FM_AT_EOD);
707 		break;
708 	default:
709 		SET(st->flags, ST_2FM_AT_EOD);
710 	}
711 	return 0;
712 }
713 
714 /*
715  * Actually translate the requested transfer into
716  * one the physical driver can understand
717  * The transfer is described by a buf and will include
718  * only one physical transfer.
719  */
720 void
721 ststrategy(struct buf *bp)
722 {
723 	struct scsi_link *link;
724 	struct st_softc *st;
725 	int s;
726 
727 	st = stlookup(STUNIT(bp->b_dev));
728 	if (st == NULL) {
729 		bp->b_error = ENXIO;
730 		goto bad;
731 	}
732 	if (ISSET(st->flags, ST_DYING)) {
733 		bp->b_error = ENXIO;
734 		goto bad;
735 	}
736 	link = st->sc_link;
737 
738 	SC_DEBUG(link, SDEV_DB2, ("ststrategy: %ld bytes @ blk %lld\n",
739 	    bp->b_bcount, (long long)bp->b_blkno));
740 
741 	/*
742 	 * If it's a null transfer, return immediately.
743 	 */
744 	if (bp->b_bcount == 0)
745 		goto done;
746 	/*
747 	 * Odd sized request on fixed drives are verboten
748 	 */
749 	if (ISSET(st->flags, ST_FIXEDBLOCKS)) {
750 		if (bp->b_bcount % st->blksize) {
751 			printf("%s: bad request, must be multiple of %d\n",
752 			    st->sc_dev.dv_xname, st->blksize);
753 			bp->b_error = EIO;
754 			goto bad;
755 		}
756 	}
757 	/*
758 	 * as are out-of-range requests on variable drives.
759 	 */
760 	else if (bp->b_bcount < st->blkmin ||
761 	    (st->blkmax && bp->b_bcount > st->blkmax)) {
762 		printf("%s: bad request, must be between %d and %d\n",
763 		    st->sc_dev.dv_xname, st->blkmin, st->blkmax);
764 		bp->b_error = EIO;
765 		goto bad;
766 	}
767 
768 	/*
769 	 * Place it in the queue of activities for this tape
770 	 * at the end (a bit silly because we only have on user..
771 	 * (but it could fork()))
772 	 */
773 	bufq_queue(&st->sc_bufq, bp);
774 
775 	/*
776 	 * Tell the device to get going on the transfer if it's
777 	 * not doing anything, otherwise just wait for completion
778 	 * (All a bit silly if we're only allowing 1 open but..)
779 	 */
780 	scsi_xsh_add(&st->sc_xsh);
781 
782 	device_unref(&st->sc_dev);
783 	return;
784 bad:
785 	SET(bp->b_flags, B_ERROR);
786 done:
787 	/* Set b_resid to indicate no xfer was done. */
788 	bp->b_resid = bp->b_bcount;
789 	s = splbio();
790 	biodone(bp);
791 	splx(s);
792 	if (st)
793 		device_unref(&st->sc_dev);
794 }
795 
796 void
797 ststart(struct scsi_xfer *xs)
798 {
799 	struct scsi_link *link = xs->sc_link;
800 	struct st_softc *st = link->device_softc;
801 	struct buf *bp;
802 	struct scsi_rw_tape *cmd;
803 	int s;
804 
805 	SC_DEBUG(link, SDEV_DB2, ("ststart\n"));
806 
807 	if (ISSET(st->flags, ST_DYING)) {
808 		scsi_xs_put(xs);
809 		return;
810 	}
811 
812 	/*
813 	 * if the device has been unmounted by the user
814 	 * then throw away all requests until done
815 	 */
816 	if (!ISSET(st->flags, ST_MOUNTED) ||
817 	    !ISSET(link->flags, SDEV_MEDIA_LOADED)) {
818 		/* make sure that one implies the other.. */
819 		CLR(link->flags, SDEV_MEDIA_LOADED);
820 		bufq_drain(&st->sc_bufq);
821 		scsi_xs_put(xs);
822 		return;
823 	}
824 
825 	for (;;) {
826 		bp = bufq_dequeue(&st->sc_bufq);
827 		if (bp == NULL) {
828 			scsi_xs_put(xs);
829 			return;
830 		}
831 
832 		/*
833 		 * Only FIXEDBLOCK devices have pending I/O or space
834 		 * operations.
835 		 */
836 		if (ISSET(st->flags, ST_FIXEDBLOCKS)) {
837 			/*
838 			 * If we are at a filemark but have not reported it yet
839 			 * then we should report it now
840 			 */
841 			if (ISSET(st->flags, ST_AT_FILEMARK)) {
842 				if ((bp->b_flags & B_READ) == B_WRITE) {
843 					/*
844 					 * Handling of ST_AT_FILEMARK in
845 					 * st_space will fill in the right file
846 					 * mark count.
847 					 * Back up over filemark
848 					 */
849 					if (st_space(st, 0, SP_FILEMARKS, 0)) {
850 						SET(bp->b_flags, B_ERROR);
851 						bp->b_resid = bp->b_bcount;
852 						bp->b_error = EIO;
853 						s = splbio();
854 						biodone(bp);
855 						splx(s);
856 						continue;
857 					}
858 				} else {
859 					bp->b_resid = bp->b_bcount;
860 					bp->b_error = 0;
861 					CLR(bp->b_flags, B_ERROR);
862 					CLR(st->flags, ST_AT_FILEMARK);
863 					s = splbio();
864 					biodone(bp);
865 					splx(s);
866 					continue;	/* seek more work */
867 				}
868 			}
869 		}
870 
871 		/*
872 		 * If we are at EIO or EOM but have not reported it
873 		 * yet then we should report it now.
874 		 */
875 		if (ISSET(st->flags, ST_EOM_PENDING | ST_EIO_PENDING)) {
876 			bp->b_resid = bp->b_bcount;
877 			if (ISSET(st->flags, ST_EIO_PENDING)) {
878 				bp->b_error = EIO;
879 				SET(bp->b_flags, B_ERROR);
880 			}
881 			CLR(st->flags, ST_EOM_PENDING | ST_EIO_PENDING);
882 			s = splbio();
883 			biodone(bp);
884 			splx(s);
885 			continue;	/* seek more work */
886 		}
887 		break;
888 	}
889 
890 	/*
891 	 *  Fill out the scsi command
892 	 */
893 	cmd = (struct scsi_rw_tape *)xs->cmd;
894 	bzero(cmd, sizeof(*cmd));
895 	if ((bp->b_flags & B_READ) == B_WRITE) {
896 		cmd->opcode = WRITE;
897 		CLR(st->flags, ST_FM_WRITTEN);
898 		SET(st->flags, ST_WRITTEN);
899 		SET(xs->flags, SCSI_DATA_OUT);
900 	} else {
901 		cmd->opcode = READ;
902 		SET(xs->flags, SCSI_DATA_IN);
903 	}
904 
905 	/*
906 	 * Handle "fixed-block-mode" tape drives by using the
907 	 * block count instead of the length.
908 	 */
909 	if (ISSET(st->flags, ST_FIXEDBLOCKS)) {
910 		SET(cmd->byte2, SRW_FIXED);
911 		_lto3b(bp->b_bcount / st->blksize, cmd->len);
912 	} else
913 		_lto3b(bp->b_bcount, cmd->len);
914 
915 	if (st->media_blkno != -1) {
916 		/* Update block count now, errors will set it to -1. */
917 		if (ISSET(st->flags, ST_FIXEDBLOCKS))
918 			st->media_blkno += _3btol(cmd->len);
919 		else if (_3btol(cmd->len) != 0)
920 			st->media_blkno++;
921 	}
922 
923 	xs->cmdlen = sizeof(*cmd);
924 	xs->timeout = ST_IO_TIME;
925 	xs->data = bp->b_data;
926 	xs->datalen = bp->b_bcount;
927 	xs->done = st_buf_done;
928 	xs->cookie = bp;
929 	xs->bp = bp;
930 
931 	/*
932 	 * go ask the adapter to do all this for us
933 	 */
934 	scsi_xs_exec(xs);
935 
936 	/*
937 	 * should we try do more work now?
938 	 */
939 	if (ISSET(st->flags, ST_WAITING))
940 		CLR(st->flags, ST_WAITING);
941 	else if (bufq_peek(&st->sc_bufq))
942 		scsi_xsh_add(&st->sc_xsh);
943 }
944 
945 void
946 st_buf_done(struct scsi_xfer *xs)
947 {
948 	struct buf *bp = xs->cookie;
949 	int error, s;
950 
951 	switch (xs->error) {
952 	case XS_NOERROR:
953 		bp->b_error = 0;
954 		CLR(bp->b_flags, B_ERROR);
955 		bp->b_resid = xs->resid;
956 		break;
957 
958 	case XS_SENSE:
959 	case XS_SHORTSENSE:
960 		SC_DEBUG_SENSE(xs);
961 		error = st_interpret_sense(xs);
962 		if (error == 0) {
963 			bp->b_error = 0;
964 			CLR(bp->b_flags, B_ERROR);
965 			bp->b_resid = xs->resid;
966 			break;
967 		}
968 		if (error != ERESTART)
969 			xs->retries = 0;
970 		goto retry;
971 
972 	case XS_BUSY:
973 		if (xs->retries) {
974 			if (scsi_delay(xs, 1) != ERESTART)
975 				xs->retries = 0;
976 		}
977 		goto retry;
978 
979 	case XS_TIMEOUT:
980  retry:
981 		if (xs->retries--) {
982 			scsi_xs_exec(xs);
983 			return;
984 		}
985 		/* FALLTHROUGH */
986 
987 	default:
988 		bp->b_error = EIO;
989 		SET(bp->b_flags, B_ERROR);
990 		bp->b_resid = bp->b_bcount;
991 		break;
992 	}
993 
994 	s = splbio();
995 	biodone(bp);
996 	splx(s);
997 	scsi_xs_put(xs);
998 }
999 
1000 void
1001 stminphys(struct buf *bp)
1002 {
1003 	struct st_softc *st;
1004 
1005 	st = stlookup(STUNIT(bp->b_dev));
1006 	if (st == NULL)
1007 		return;
1008 
1009 	(*st->sc_link->adapter->scsi_minphys)(bp, st->sc_link);
1010 
1011 	device_unref(&st->sc_dev);
1012 }
1013 
1014 int
1015 stread(dev_t dev, struct uio *uio, int iomode)
1016 {
1017 	return physio(ststrategy, dev, B_READ, stminphys, uio);
1018 }
1019 
1020 int
1021 stwrite(dev_t dev, struct uio *uio, int iomode)
1022 {
1023 	return physio(ststrategy, dev, B_WRITE, stminphys, uio);
1024 }
1025 
1026 /*
1027  * Perform special action on behalf of the user;
1028  * knows about the internals of this device
1029  */
1030 int
1031 stioctl(dev_t dev, u_long cmd, caddr_t arg, int flag, struct proc *p)
1032 {
1033 	int error = 0;
1034 	int nmarks;
1035 	int flags = 0;
1036 	struct st_softc *st;
1037 	int hold_blksize;
1038 	u_int8_t hold_density;
1039 	struct mtop *mt = (struct mtop *) arg;
1040 	int number;
1041 
1042 	/*
1043 	 * Find the device that the user is talking about
1044 	 */
1045 	st = stlookup(STUNIT(dev));
1046 	if (st == NULL)
1047 		return ENXIO;
1048 
1049 	if (ISSET(st->flags, ST_DYING)) {
1050 		error = ENXIO;
1051 		goto done;
1052 	}
1053 
1054 	hold_blksize = st->blksize;
1055 	hold_density = st->density;
1056 
1057 	switch (cmd) {
1058 
1059 	case MTIOCGET: {
1060 		struct mtget *g = (struct mtget *) arg;
1061 
1062 		/*
1063 		 * (to get the current state of READONLY)
1064 		 */
1065 		error = st_mode_sense(st, SCSI_SILENT);
1066 		if (error != 0)
1067 			break;
1068 
1069 		SC_DEBUG(st->sc_link, SDEV_DB1, ("[ioctl: get status]\n"));
1070 		bzero(g, sizeof(struct mtget));
1071 		g->mt_type = 0x7;	/* Ultrix compat *//*? */
1072 		g->mt_blksiz = st->blksize;
1073 		g->mt_density = st->density;
1074 		g->mt_mblksiz = st->mode.blksize;
1075 		g->mt_mdensity = st->mode.density;
1076 		if (ISSET(st->sc_link->flags, SDEV_READONLY))
1077 			SET(g->mt_dsreg, MT_DS_RDONLY);
1078 		if (ISSET(st->flags, ST_MOUNTED))
1079 			SET(g->mt_dsreg, MT_DS_MOUNTED);
1080 		g->mt_resid = st->mt_resid;
1081 		g->mt_erreg = st->mt_erreg;
1082 		g->mt_fileno = st->media_fileno;
1083 		g->mt_blkno = st->media_blkno;
1084 		/*
1085 		 * clear latched errors.
1086 		 */
1087 		st->mt_resid = 0;
1088 		st->mt_erreg = 0;
1089 		break;
1090 	}
1091 	case MTIOCTOP: {
1092 
1093 		SC_DEBUG(st->sc_link, SDEV_DB1,
1094 		    ("[ioctl: op=0x%x count=0x%x]\n", mt->mt_op, mt->mt_count));
1095 
1096 		number = mt->mt_count;
1097 		switch (mt->mt_op) {
1098 		case MTWEOF:	/* write an end-of-file record */
1099 			error = st_write_filemarks(st, number, flags);
1100 			break;
1101 		case MTBSF:	/* backward space file */
1102 			number = -number;
1103 		case MTFSF:	/* forward space file */
1104 			error = st_check_eod(st, 0, &nmarks, flags);
1105 			if (error == 0)
1106 				error = st_space(st, number - nmarks,
1107 				    SP_FILEMARKS, flags);
1108 			break;
1109 		case MTBSR:	/* backward space record */
1110 			number = -number;
1111 		case MTFSR:	/* forward space record */
1112 			error = st_check_eod(st, 1, &nmarks, flags);
1113 			if (error == 0)
1114 				error = st_space(st, number, SP_BLKS, flags);
1115 			break;
1116 		case MTREW:	/* rewind */
1117 			error = st_rewind(st, 0, flags);
1118 			break;
1119 		case MTOFFL:	/* rewind and put the drive offline */
1120 			st_unmount(st, EJECT, DOREWIND);
1121 			break;
1122 		case MTNOP:	/* no operation, sets status only */
1123 			break;
1124 		case MTRETEN:	/* retension the tape */
1125 			error = st_load(st, LD_RETENSION, flags);
1126 			if (error == 0)
1127 				error = st_load(st, LD_LOAD, flags);
1128 			break;
1129 		case MTEOM:	/* forward space to end of media */
1130 			error = st_check_eod(st, 0, &nmarks, flags);
1131 			if (error == 0)
1132 				error = st_space(st, 1, SP_EOM, flags);
1133 			break;
1134 		case MTCACHE:	/* enable controller cache */
1135 			CLR(st->flags, ST_DONTBUFFER);
1136 			goto try_new_value;
1137 		case MTNOCACHE:	/* disable controller cache */
1138 			SET(st->flags, ST_DONTBUFFER);
1139 			goto try_new_value;
1140 		case MTERASE:	/* erase volume */
1141 			error = st_erase(st, number, flags);
1142 			break;
1143 		case MTSETBSIZ:	/* Set block size for device and mode. */
1144 			if (number == 0) {
1145 				CLR(st->flags, ST_FIXEDBLOCKS);
1146 			} else {
1147 				if ((st->blkmin || st->blkmax) &&
1148 				    (number < st->blkmin ||
1149 				    number > st->blkmax)) {
1150 					error = EINVAL;
1151 					break;
1152 				}
1153 				SET(st->flags, ST_FIXEDBLOCKS);
1154 			}
1155 			st->blksize = number;
1156 			goto try_new_value;
1157 
1158 		case MTSETDNSTY:	/* Set density for device and mode. */
1159 			if (number < 0 || number > SCSI_MAX_DENSITY_CODE) {
1160 				error = EINVAL;
1161 				break;
1162 			}
1163 			st->density = number;
1164 			goto try_new_value;
1165 
1166 		default:
1167 			error = EINVAL;
1168 		}
1169 		break;
1170 	}
1171 	case MTIOCIEOT:
1172 	case MTIOCEEOT:
1173 		break;
1174 
1175 #if 0
1176 	case MTIOCRDSPOS:
1177 		error = st_rdpos(st, 0, (u_int32_t *) arg);
1178 		break;
1179 
1180 	case MTIOCRDHPOS:
1181 		error = st_rdpos(st, 1, (u_int32_t *) arg);
1182 		break;
1183 
1184 	case MTIOCSLOCATE:
1185 		error = st_setpos(st, 0, (u_int32_t *) arg);
1186 		break;
1187 
1188 	case MTIOCHLOCATE:
1189 		error = st_setpos(st, 1, (u_int32_t *) arg);
1190 		break;
1191 #endif /* 0 */
1192 
1193 	default:
1194 		error = scsi_do_ioctl(st->sc_link, cmd, arg, flag);
1195 		break;
1196 	}
1197 	goto done;
1198 
1199 try_new_value:
1200 	/*
1201 	 * Check that the mode being asked for is aggreeable to the
1202 	 * drive. If not, put it back the way it was.
1203 	 */
1204 	if ((error = st_mode_select(st, 0)) != 0) {/* put it back as it was */
1205 		printf("%s: cannot set selected mode\n", st->sc_dev.dv_xname);
1206 		st->density = hold_density;
1207 		st->blksize = hold_blksize;
1208 		if (st->blksize)
1209 			SET(st->flags, ST_FIXEDBLOCKS);
1210 		else
1211 			CLR(st->flags, ST_FIXEDBLOCKS);
1212 		goto done;
1213 	}
1214 	/*
1215 	 * As the drive liked it, if we are setting a new default,
1216 	 * set it into the structures as such.
1217 	 */
1218 	switch (mt->mt_op) {
1219 	case MTSETBSIZ:
1220 		st->mode.blksize = st->blksize;
1221 		SET(st->flags, ST_MODE_BLKSIZE);
1222 		break;
1223 	case MTSETDNSTY:
1224 		st->mode.density = st->density;
1225 		SET(st->flags, ST_MODE_DENSITY);
1226 		break;
1227 	}
1228 
1229 done:
1230 	device_unref(&st->sc_dev);
1231 	return error;
1232 }
1233 
1234 /*
1235  * Do a synchronous read.
1236  */
1237 int
1238 st_read(struct st_softc *st, char *buf, int size, int flags)
1239 {
1240 	struct scsi_rw_tape *cmd;
1241 	struct scsi_xfer *xs;
1242 	int error;
1243 
1244 	if (size == 0)
1245 		return 0;
1246 
1247 	xs = scsi_xs_get(st->sc_link, flags | SCSI_DATA_IN);
1248 	if (xs == NULL)
1249 		return ENOMEM;
1250 	xs->cmdlen = sizeof(*cmd);
1251 	xs->data = buf;
1252 	xs->datalen = size;
1253 	xs->retries = 0;
1254 	xs->timeout = ST_IO_TIME;
1255 
1256 	cmd = (struct scsi_rw_tape *)xs->cmd;
1257 	cmd->opcode = READ;
1258 	if (ISSET(st->flags, ST_FIXEDBLOCKS)) {
1259 		SET(cmd->byte2, SRW_FIXED);
1260 		_lto3b(size / (st->blksize ? st->blksize : DEF_FIXED_BSIZE),
1261 		    cmd->len);
1262 	} else
1263 		_lto3b(size, cmd->len);
1264 
1265 	error = scsi_xs_sync(xs);
1266 	scsi_xs_put(xs);
1267 
1268 	return error;
1269 }
1270 
1271 /*
1272  * Ask the drive what its min and max blk sizes are.
1273  */
1274 int
1275 st_read_block_limits(struct st_softc *st, int flags)
1276 {
1277 	struct scsi_block_limits_data *block_limits = NULL;
1278 	struct scsi_block_limits *cmd;
1279 	struct scsi_link *link = st->sc_link;
1280 	struct scsi_xfer *xs;
1281 	int error = 0;
1282 
1283 	if (ISSET(link->flags, SDEV_MEDIA_LOADED))
1284 		return 0;
1285 
1286 	block_limits = dma_alloc(sizeof(*block_limits), PR_NOWAIT);
1287 	if (block_limits == NULL)
1288 		return ENOMEM;
1289 
1290 	xs = scsi_xs_get(link, flags | SCSI_DATA_IN);
1291 	if (xs == NULL) {
1292 		error = ENOMEM;
1293 		goto done;
1294 	}
1295 
1296 	xs->cmdlen = sizeof(*cmd);
1297 	xs->data = (void *)block_limits;
1298 	xs->datalen = sizeof(*block_limits);
1299 	xs->timeout = ST_CTL_TIME;
1300 
1301 	cmd = (struct scsi_block_limits *)xs->cmd;
1302 	cmd->opcode = READ_BLOCK_LIMITS;
1303 
1304 	error = scsi_xs_sync(xs);
1305 	scsi_xs_put(xs);
1306 
1307 	if (error == 0) {
1308 		st->blkmin = _2btol(block_limits->min_length);
1309 		st->blkmax = _3btol(block_limits->max_length);
1310 		SC_DEBUG(link, SDEV_DB3,
1311 		    ("(%d <= blksize <= %d)\n", st->blkmin, st->blkmax));
1312 	}
1313 
1314 done:
1315 	if (block_limits)
1316 		dma_free(block_limits, sizeof(*block_limits));
1317 	return error;
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(struct st_softc *st, int flags)
1332 {
1333 	union scsi_mode_sense_buf *data = NULL;
1334 	struct scsi_link *link = st->sc_link;
1335 	u_int64_t block_count;
1336 	u_int32_t density, block_size;
1337 	u_char *page0 = NULL;
1338 	u_int8_t dev_spec;
1339 	int error = 0, big;
1340 
1341 	data = dma_alloc(sizeof(*data), PR_NOWAIT);
1342 	if (data == NULL)
1343 		return ENOMEM;
1344 
1345 	/*
1346 	 * Ask for page 0 (vendor specific) mode sense data.
1347 	 */
1348 	density = 0;
1349 	block_count = 0;
1350 	block_size = 0;
1351 	error = scsi_do_mode_sense(link, 0, data, (void **)&page0,
1352 	    &density, &block_count, &block_size, 1, flags | SCSI_SILENT, &big);
1353 	if (error != 0)
1354 		goto done;
1355 
1356 	/* It is valid for no page0 to be available. */
1357 
1358 	if (big)
1359 		dev_spec = data->hdr_big.dev_spec;
1360 	else
1361 		dev_spec = data->hdr.dev_spec;
1362 
1363 	if (ISSET(dev_spec, SMH_DSP_WRITE_PROT))
1364 		SET(link->flags, SDEV_READONLY);
1365 	else
1366 		CLR(link->flags, SDEV_READONLY);
1367 
1368 	st->media_blksize = block_size;
1369 	st->media_density = density;
1370 
1371 	SC_DEBUG(link, SDEV_DB3,
1372 	    ("density code 0x%x, %d-byte blocks, write-%s, %sbuffered\n",
1373 	    st->media_density, st->media_blksize,
1374 	    ISSET(link->flags, SDEV_READONLY) ? "protected" : "enabled",
1375 	    ISSET(dev_spec, SMH_DSP_BUFF_MODE) ? "" : "un"));
1376 
1377 	SET(link->flags, SDEV_MEDIA_LOADED);
1378 
1379  done:
1380 	if (data)
1381 		dma_free(data, sizeof(*data));
1382 	return error;
1383 }
1384 
1385 /*
1386  * Send a filled out parameter structure to the drive to
1387  * set it into the desire mode etc.
1388  */
1389 int
1390 st_mode_select(struct st_softc *st, int flags)
1391 {
1392 	union scsi_mode_sense_buf *inbuf = NULL, *outbuf = NULL;
1393 	struct scsi_blk_desc general;
1394 	struct scsi_link *link = st->sc_link;
1395 	u_int8_t *page0 = NULL;
1396 	int error = 0, big, page0_size;
1397 
1398 	inbuf = dma_alloc(sizeof(*inbuf), PR_NOWAIT);
1399 	if (inbuf == NULL) {
1400 		error = ENOMEM;
1401 		goto done;
1402 	}
1403 	outbuf = dma_alloc(sizeof(*outbuf), PR_NOWAIT | PR_ZERO);
1404 	if (outbuf == NULL) {
1405 		error = ENOMEM;
1406 		goto done;
1407 	}
1408 
1409 	/*
1410 	 * This quirk deals with drives that have only one valid mode and think
1411 	 * this gives them license to reject all mode selects, even if the
1412 	 * selected mode is the one that is supported.
1413 	 */
1414 	if (ISSET(st->quirks, ST_Q_UNIMODAL)) {
1415 		SC_DEBUG(link, SDEV_DB3,
1416 		    ("not setting density 0x%x blksize 0x%x\n",
1417 		    st->density, st->blksize));
1418 		error = 0;
1419 		goto done;
1420 	}
1421 
1422 	if (ISSET(link->flags, SDEV_ATAPI)) {
1423 		error = 0;
1424 		goto done;
1425 	}
1426 
1427 	bzero(&general, sizeof(general));
1428 
1429 	general.density = st->density;
1430 	if (ISSET(st->flags, ST_FIXEDBLOCKS))
1431 		_lto3b(st->blksize, general.blklen);
1432 
1433 	/*
1434 	 * Ask for page 0 (vendor specific) mode sense data.
1435 	 */
1436 	error = scsi_do_mode_sense(link, 0, inbuf, (void **)&page0, NULL,
1437 	    NULL, NULL, 1, flags | SCSI_SILENT, &big);
1438 	if (error != 0)
1439 		goto done;
1440 
1441 	if (page0 == NULL) {
1442 		page0_size = 0;
1443 	} else if (big == 0) {
1444 		page0_size = inbuf->hdr.data_length +
1445 		    sizeof(inbuf->hdr.data_length) - sizeof(inbuf->hdr) -
1446 		    inbuf->hdr.blk_desc_len;
1447 		memcpy(&outbuf->buf[sizeof(outbuf->hdr)+ sizeof(general)],
1448 		    page0, page0_size);
1449 	} else {
1450 		page0_size = _2btol(inbuf->hdr_big.data_length) +
1451 		    sizeof(inbuf->hdr_big.data_length) -
1452 		    sizeof(inbuf->hdr_big) -
1453 		    _2btol(inbuf->hdr_big.blk_desc_len);
1454 		memcpy(&outbuf->buf[sizeof(outbuf->hdr_big) + sizeof(general)],
1455 		    page0, page0_size);
1456 	}
1457 
1458 	/*
1459 	 * Set up for a mode select.
1460 	 */
1461 	if (big == 0) {
1462 		outbuf->hdr.data_length = sizeof(outbuf->hdr) +
1463 		    sizeof(general) + page0_size -
1464 		    sizeof(outbuf->hdr.data_length);
1465 		if (!ISSET(st->flags, ST_DONTBUFFER))
1466 			outbuf->hdr.dev_spec = SMH_DSP_BUFF_MODE_ON;
1467 		outbuf->hdr.blk_desc_len = sizeof(general);
1468 		memcpy(&outbuf->buf[sizeof(outbuf->hdr)],
1469 		    &general, sizeof(general));
1470 		error = scsi_mode_select(st->sc_link, 0, &outbuf->hdr,
1471 		    flags, ST_CTL_TIME);
1472 		goto done;
1473 	}
1474 
1475 	/* MODE SENSE (10) header was returned, so use MODE SELECT (10). */
1476 	_lto2b((sizeof(outbuf->hdr_big) + sizeof(general) + page0_size -
1477 	    sizeof(outbuf->hdr_big.data_length)), outbuf->hdr_big.data_length);
1478 	if (!ISSET(st->flags, ST_DONTBUFFER))
1479 		outbuf->hdr_big.dev_spec = SMH_DSP_BUFF_MODE_ON;
1480 	_lto2b(sizeof(general), outbuf->hdr_big.blk_desc_len);
1481 	memcpy(&outbuf->buf[sizeof(outbuf->hdr_big)], &general,
1482 	    sizeof(general));
1483 
1484 	error = scsi_mode_select_big(st->sc_link, 0, &outbuf->hdr_big,
1485 	    flags, ST_CTL_TIME);
1486 done:
1487 	if (inbuf)
1488 		dma_free(inbuf, sizeof(*inbuf));
1489 	if (outbuf)
1490 		dma_free(outbuf, sizeof(*outbuf));
1491 	return error;
1492 }
1493 
1494 /*
1495  * issue an erase command
1496  */
1497 int
1498 st_erase(struct st_softc *st, int full, int flags)
1499 {
1500 	struct scsi_erase *cmd;
1501 	struct scsi_xfer *xs;
1502 	int error;
1503 
1504 	xs = scsi_xs_get(st->sc_link, flags);
1505 	if (xs == NULL)
1506 		return ENOMEM;
1507 	xs->cmdlen = sizeof(*cmd);
1508 
1509 	/*
1510 	 * Full erase means set LONG bit in erase command, which asks
1511 	 * the drive to erase the entire unit.  Without this bit, we're
1512 	 * asking the drive to write an erase gap.
1513 	 */
1514 	cmd = (struct scsi_erase *)xs->cmd;
1515 	cmd->opcode = ERASE;
1516 	if (full) {
1517 		cmd->byte2 = SE_IMMED|SE_LONG;
1518 		xs->timeout = ST_SPC_TIME;
1519 	} else {
1520 		cmd->byte2 = SE_IMMED;
1521 		xs->timeout = ST_IO_TIME;
1522 	}
1523 
1524 	/*
1525 	 * XXX We always do this asynchronously, for now.  How long should
1526 	 * we wait if we want to (eventually) to it synchronously?
1527 	 */
1528 	error = scsi_xs_sync(xs);
1529 	scsi_xs_put(xs);
1530 
1531 	return error;
1532 }
1533 
1534 /*
1535  * skip N blocks/filemarks/seq filemarks/eom
1536  */
1537 int
1538 st_space(struct st_softc *st, int number, u_int what, int flags)
1539 {
1540 	struct scsi_space *cmd;
1541 	struct scsi_xfer *xs;
1542 	int error;
1543 
1544 	switch (what) {
1545 	case SP_BLKS:
1546 		if (ISSET(st->flags, ST_PER_ACTION)) {
1547 			if (number > 0) {
1548 				CLR(st->flags, ST_PER_ACTION);
1549 				return EIO;
1550 			} else if (number < 0) {
1551 				if (ISSET(st->flags, ST_AT_FILEMARK)) {
1552 					/*
1553 					 * Handling of ST_AT_FILEMARK
1554 					 * in st_space will fill in the
1555 					 * right file mark count.
1556 					 */
1557 					error = st_space(st, 0, SP_FILEMARKS,
1558 					    flags);
1559 					if (error != 0)
1560 						return error;
1561 				}
1562 				if (ISSET(st->flags, ST_BLANK_READ)) {
1563 					CLR(st->flags, ST_BLANK_READ);
1564 					return EIO;
1565 				}
1566 				CLR(st->flags, ST_EIO_PENDING | ST_EOM_PENDING);
1567 			}
1568 		}
1569 		break;
1570 	case SP_FILEMARKS:
1571 		if (ISSET(st->flags,  ST_EIO_PENDING)) {
1572 			if (number > 0) {
1573 				/* pretend we just discovered the error */
1574 				CLR(st->flags, ST_EIO_PENDING);
1575 				return EIO;
1576 			} else if (number < 0) {
1577 				/* back away from the error */
1578 				CLR(st->flags, ST_EIO_PENDING);
1579 			}
1580 		}
1581 		if (ISSET(st->flags, ST_AT_FILEMARK)) {
1582 			CLR(st->flags, ST_AT_FILEMARK);
1583 			number--;
1584 		}
1585 		if (ISSET(st->flags, ST_BLANK_READ) && (number < 0)) {
1586 			/* back away from unwritten tape */
1587 			CLR(st->flags, ST_BLANK_READ);
1588 			number++;	/* XXX dubious */
1589 		}
1590 		break;
1591 	case SP_EOM:
1592 		if (ISSET(st->flags, ST_EOM_PENDING)) {
1593 			/* We are already there. */
1594 			CLR(st->flags, ST_EOM_PENDING);
1595 			return 0;
1596 		}
1597 		if (ISSET(st->flags, ST_EIO_PENDING)) {
1598 			/* pretend we just discovered the error */
1599 			CLR(st->flags, ST_EIO_PENDING);
1600 			return EIO;
1601 		}
1602 		if (ISSET(st->flags, ST_AT_FILEMARK))
1603 			CLR(st->flags, ST_AT_FILEMARK);
1604 		break;
1605 	}
1606 	if (number == 0)
1607 		return 0;
1608 
1609 	xs = scsi_xs_get(st->sc_link, flags);
1610 	if (xs == NULL)
1611 		return ENOMEM;
1612 
1613 	cmd = (struct scsi_space *)xs->cmd;
1614 	cmd->opcode = SPACE;
1615 	cmd->byte2 = what;
1616 	_lto3b(number, cmd->number);
1617 	xs->cmdlen = sizeof(*cmd);
1618 	xs->timeout = ST_SPC_TIME;
1619 
1620 	CLR(st->flags, ST_EOD_DETECTED);
1621 
1622 	error = scsi_xs_sync(xs);
1623 	scsi_xs_put(xs);
1624 
1625 	if (error != 0) {
1626 		st->media_fileno = -1;
1627 		st->media_blkno = -1;
1628 	} else {
1629 		switch (what) {
1630 		case SP_BLKS:
1631 			if (st->media_blkno != -1) {
1632 				st->media_blkno += number;
1633 				if (st->media_blkno < 0)
1634 					st->media_blkno = -1;
1635 			}
1636 			break;
1637 		case SP_FILEMARKS:
1638 			if (st->media_fileno != -1) {
1639 				if (!ISSET(st->flags, ST_EOD_DETECTED))
1640 					st->media_fileno += number;
1641 				if (st->media_fileno > st->media_eom)
1642 					st->media_eom = st->media_fileno;
1643 				st->media_blkno = 0;
1644 			}
1645 			break;
1646 		case SP_EOM:
1647 			if (st->media_eom != -1) {
1648 				st->media_fileno = st->media_eom;
1649 				st->media_blkno = 0;
1650 			} else {
1651 				st->media_fileno = -1;
1652 				st->media_blkno = -1;
1653 			}
1654 			break;
1655 		default:
1656 			st->media_fileno = -1;
1657 			st->media_blkno = -1;
1658 			break;
1659 		}
1660 	}
1661 
1662 	return error;
1663 }
1664 
1665 /*
1666  * write N filemarks
1667  */
1668 int
1669 st_write_filemarks(struct st_softc *st, int number, int flags)
1670 {
1671 	struct scsi_write_filemarks *cmd;
1672 	struct scsi_xfer *xs;
1673 	int error;
1674 
1675 	if (number < 0)
1676 		return EINVAL;
1677 
1678 	xs = scsi_xs_get(st->sc_link, flags);
1679 	if (xs == NULL)
1680 		return ENOMEM;
1681 
1682 	xs->cmdlen = sizeof(*cmd);
1683 	xs->timeout = ST_IO_TIME * 4;
1684 
1685 	switch (number) {
1686 	case 0:		/* really a command to sync the drive's buffers */
1687 		break;
1688 	case 1:
1689 		if (ISSET(st->flags, ST_FM_WRITTEN))	/* already have one down */
1690 			CLR(st->flags, ST_WRITTEN);
1691 		else
1692 			SET(st->flags, ST_FM_WRITTEN);
1693 		CLR(st->flags, ST_PER_ACTION);
1694 		break;
1695 	default:
1696 		CLR(st->flags, ST_PER_ACTION | ST_WRITTEN);
1697 		break;
1698 	}
1699 
1700 	cmd = (struct scsi_write_filemarks *)xs->cmd;
1701 	cmd->opcode = WRITE_FILEMARKS;
1702 	_lto3b(number, cmd->number);
1703 
1704 	error = scsi_xs_sync(xs);
1705 	scsi_xs_put(xs);
1706 
1707 	if (error != 0) {
1708 		st->media_fileno = -1;
1709 		st->media_blkno = -1;
1710 		st->media_eom = -1;
1711 	} else if (st->media_fileno != -1) {
1712 		st->media_fileno += number;
1713 		st->media_eom = st->media_fileno;
1714 		st->media_blkno = 0;
1715 	}
1716 
1717 	return error;
1718 }
1719 
1720 /*
1721  * Make sure the right number of file marks is on tape if the
1722  * tape has been written.  If the position argument is true,
1723  * leave the tape positioned where it was originally.
1724  *
1725  * nmarks returns the number of marks to skip (or, if position
1726  * true, which were skipped) to get back original position.
1727  */
1728 int
1729 st_check_eod(struct st_softc *st, int position, int *nmarks, int flags)
1730 {
1731 	int error;
1732 
1733 	switch (st->flags & (ST_WRITTEN | ST_FM_WRITTEN | ST_2FM_AT_EOD)) {
1734 	default:
1735 		*nmarks = 0;
1736 		return 0;
1737 	case ST_WRITTEN:
1738 	case ST_WRITTEN | ST_FM_WRITTEN | ST_2FM_AT_EOD:
1739 		*nmarks = 1;
1740 		break;
1741 	case ST_WRITTEN | ST_2FM_AT_EOD:
1742 		*nmarks = 2;
1743 	}
1744 	error = st_write_filemarks(st, *nmarks, flags);
1745 	if (error == 0 && position != 0)
1746 		error = st_space(st, -*nmarks, SP_FILEMARKS, flags);
1747 	return error;
1748 }
1749 
1750 /*
1751  * load/unload/retension
1752  */
1753 int
1754 st_load(struct st_softc *st, u_int type, int flags)
1755 {
1756 	struct scsi_load *cmd;
1757 	struct scsi_xfer *xs;
1758 	int error, nmarks;
1759 
1760 	st->media_fileno = -1;
1761 	st->media_blkno = -1;
1762 	st->media_eom = -1;
1763 
1764 	if (type != LD_LOAD) {
1765 		error = st_check_eod(st, 0, &nmarks, flags);
1766 		if (error != 0)
1767 			return error;
1768 	}
1769 
1770 	if (ISSET(st->quirks, ST_Q_IGNORE_LOADS)) {
1771 		if (type == LD_LOAD) {
1772 			/*
1773 			 * If we ignore loads, at least we should try a rewind.
1774 			 */
1775 			return st_rewind(st, 0, flags);
1776 		}
1777 		return 0;
1778 	}
1779 
1780 
1781 	xs = scsi_xs_get(st->sc_link, flags);
1782 	if (xs == NULL)
1783 		return ENOMEM;
1784 	xs->cmdlen = sizeof(*cmd);
1785 	xs->timeout = ST_SPC_TIME;
1786 
1787 	cmd = (struct scsi_load *)xs->cmd;
1788 	cmd->opcode = LOAD;
1789 	cmd->how = type;
1790 
1791 	error = scsi_xs_sync(xs);
1792 	scsi_xs_put(xs);
1793 
1794 	return error;
1795 }
1796 
1797 /*
1798  *  Rewind the device
1799  */
1800 int
1801 st_rewind(struct st_softc *st, u_int immediate, int flags)
1802 {
1803 	struct scsi_rewind *cmd;
1804 	struct scsi_xfer *xs;
1805 	int error, nmarks;
1806 
1807 	error = st_check_eod(st, 0, &nmarks, flags);
1808 	if (error != 0)
1809 		return error;
1810 	CLR(st->flags, ST_PER_ACTION);
1811 
1812 	xs = scsi_xs_get(st->sc_link, flags);
1813 	if (xs == NULL)
1814 		return ENOMEM;
1815 	xs->cmdlen = sizeof(*cmd);
1816 	xs->timeout = immediate ? ST_CTL_TIME : ST_SPC_TIME;
1817 
1818 	cmd = (struct scsi_rewind *)xs->cmd;
1819 	cmd->opcode = REWIND;
1820 	cmd->byte2 = immediate;
1821 
1822 	error = scsi_xs_sync(xs);
1823 	scsi_xs_put(xs);
1824 
1825 	if (error == 0) {
1826 		st->media_fileno = 0;
1827 		st->media_blkno = 0;
1828 	}
1829 
1830 	return error;
1831 }
1832 
1833 /*
1834  * Look at the returned sense and act on the error and detirmine
1835  * The unix error number to pass back... (0 = report no error)
1836  *                            (-1 = continue processing)
1837  */
1838 int
1839 st_interpret_sense(struct scsi_xfer *xs)
1840 {
1841 	struct scsi_sense_data *sense = &xs->sense;
1842 	struct scsi_link *link = xs->sc_link;
1843 	struct scsi_space *space;
1844 	struct st_softc *st = link->device_softc;
1845 	u_int8_t serr = sense->error_code & SSD_ERRCODE;
1846 	u_int8_t skey = sense->flags & SSD_KEY;
1847 	int32_t resid, info, number;
1848 	int datalen;
1849 
1850 	if (!ISSET(link->flags, SDEV_OPEN) ||
1851 	    (serr != SSD_ERRCODE_CURRENT && serr != SSD_ERRCODE_DEFERRED))
1852 		return scsi_interpret_sense(xs);
1853 
1854 	info = (int32_t)_4btol(sense->info);
1855 
1856 	switch (skey) {
1857 
1858 	/*
1859 	 * We do custom processing in st for the unit becoming ready case.
1860 	 * in this case we do not allow xs->retries to be decremented
1861 	 * only on the "Unit Becoming Ready" case. This is because tape
1862 	 * drives report "Unit Becoming Ready" when loading media, etc.
1863 	 * and can take a long time.  Rather than having a massive timeout
1864 	 * for all operations (which would cause other problems) we allow
1865 	 * operations to wait (but be interruptable with Ctrl-C) forever
1866 	 * as long as the drive is reporting that it is becoming ready.
1867 	 * all other cases are handled as per the default.
1868 	 */
1869 
1870 	case SKEY_NOT_READY:
1871 		if (ISSET(xs->flags, SCSI_IGNORE_NOT_READY))
1872 			return 0;
1873 		switch (ASC_ASCQ(sense)) {
1874 		case SENSE_NOT_READY_BECOMING_READY:
1875 			SC_DEBUG(link, SDEV_DB1, ("not ready: busy (%#x)\n",
1876 			    sense->add_sense_code_qual));
1877 			/* don't count this as a retry */
1878 			xs->retries++;
1879 			return scsi_delay(xs, 1);
1880 		default:
1881 			return scsi_interpret_sense(xs);
1882 		}
1883 		break;
1884 	case SKEY_BLANK_CHECK:
1885 		if (sense->error_code & SSD_ERRCODE_VALID &&
1886 		    xs->cmd->opcode == SPACE) {
1887 			switch (ASC_ASCQ(sense)) {
1888 			case SENSE_END_OF_DATA_DETECTED:
1889 				SET(st->flags, ST_EOD_DETECTED);
1890 				space = (struct scsi_space *)xs->cmd;
1891 				number = _3btol(space->number);
1892 				st->media_fileno = number - info;
1893 				st->media_eom = st->media_fileno;
1894 				return 0;
1895 			case SENSE_BEGINNING_OF_MEDIUM_DETECTED:
1896 				/* Standard says: Position is undefined! */
1897 				SET(st->flags, ST_BOD_DETECTED);
1898 				st->media_fileno = -1;
1899 				st->media_blkno = -1;
1900 				return 0;
1901 			}
1902 		}
1903 		break;
1904 	case SKEY_NO_SENSE:
1905 	case SKEY_RECOVERED_ERROR:
1906 	case SKEY_MEDIUM_ERROR:
1907 	case SKEY_VOLUME_OVERFLOW:
1908 		break;
1909 	default:
1910 		return scsi_interpret_sense(xs);
1911 	}
1912 
1913 	/*
1914 	 * 'resid' can be in units of st->blksize or bytes. xs->resid and
1915 	 * xs->datalen are always in units of bytes. So we need a variable
1916 	 * to store datalen in the same units as resid and to adjust
1917 	 * xs->resid to be in bytes.
1918 	 */
1919 	if (ISSET(sense->error_code, SSD_ERRCODE_VALID)) {
1920 		if (ISSET(st->flags, ST_FIXEDBLOCKS))
1921 			resid = info * st->blksize; /* XXXX overflow? */
1922 		else
1923 			resid = info;
1924 	} else {
1925 		resid = xs->datalen;
1926 	}
1927 
1928 	if (resid < 0 || resid > xs->datalen)
1929 		xs->resid = xs->datalen;
1930 	else
1931 		xs->resid = resid;
1932 
1933 	datalen = xs->datalen;
1934 	if (ISSET(st->flags, ST_FIXEDBLOCKS)) {
1935 		resid /= st->blksize;
1936 		datalen /= st->blksize;
1937 	}
1938 
1939 	if (ISSET(sense->flags, SSD_FILEMARK)) {
1940 		if (st->media_fileno != -1) {
1941 			st->media_fileno++;
1942 			if (st->media_fileno > st->media_eom)
1943 				st->media_eom = st->media_fileno;
1944 			st->media_blkno = 0;
1945 		}
1946 		if (!ISSET(st->flags, ST_FIXEDBLOCKS))
1947 			return 0;
1948 		SET(st->flags, ST_AT_FILEMARK);
1949 	}
1950 
1951 	if (ISSET(sense->flags, SSD_EOM)) {
1952 		SET(st->flags, ST_EOM_PENDING);
1953 		xs->resid = 0;
1954 		if (ISSET(st->flags, ST_FIXEDBLOCKS))
1955 			return 0;
1956 	}
1957 
1958 	if (ISSET(sense->flags, SSD_ILI)) {
1959 		if (!ISSET(st->flags, ST_FIXEDBLOCKS)) {
1960 			if (resid >= 0 && resid <= datalen)
1961 				return 0;
1962 			if (!ISSET(xs->flags, SCSI_SILENT))
1963 				printf( "%s: bad residual %d out of "
1964 				    "%d\n", st->sc_dev.dv_xname, resid,
1965 				    datalen);
1966 			return EIO;
1967 		}
1968 
1969 		/* Fixed size blocks. */
1970 		if (ISSET(sense->error_code, SSD_ERRCODE_VALID))
1971 			if (!ISSET(xs->flags, SCSI_SILENT))
1972 				printf("%s: block wrong size, %d blocks "
1973 				    "residual\n", st->sc_dev.dv_xname, resid);
1974 		SET(st->flags, ST_EIO_PENDING);
1975 		/*
1976 		 * This quirk code helps the drive read the first tape block,
1977 		 * regardless of format.  That is required for these drives to
1978 		 * return proper MODE SENSE information.
1979 		 */
1980 		if (ISSET(st->quirks, ST_Q_SENSE_HELP) &&
1981 		    !ISSET(link->flags, SDEV_MEDIA_LOADED))
1982 			st->blksize -= 512;
1983 	}
1984 
1985 	if (ISSET(st->flags, ST_FIXEDBLOCKS) && xs->resid == xs->datalen) {
1986 		if (ISSET(st->flags, ST_EIO_PENDING))
1987 			return EIO;
1988 		if (ISSET(st->flags, ST_AT_FILEMARK))
1989 			return 0;
1990 	}
1991 
1992 	if (skey == SKEY_BLANK_CHECK) {
1993 		/*
1994 		 * This quirk code helps the drive read the first tape block,
1995 		 * regardless of format.  That is required for these drives to
1996 		 * return proper MODE SENSE information.
1997 		 */
1998 		if (ISSET(st->quirks, ST_Q_SENSE_HELP) &&
1999 		    !ISSET(link->flags, SDEV_MEDIA_LOADED)) {
2000 			/* still starting */
2001 			st->blksize -= 512;
2002 		} else if (!ISSET(st->flags, ST_2FM_AT_EOD | ST_BLANK_READ)) {
2003 			SET(st->flags, ST_BLANK_READ);
2004 			SET(st->flags, ST_EOM_PENDING);
2005 			xs->resid = xs->datalen;
2006 			return 0;
2007 		}
2008 	}
2009 
2010 	return scsi_interpret_sense(xs);
2011 }
2012 
2013 /*
2014  * The quirk here is that the drive returns some value to st_mode_sense
2015  * incorrectly until the tape has actually passed by the head.
2016  *
2017  * The method is to set the drive to large fixed-block state (user-specified
2018  * density and 1024-byte blocks), then read and rewind to get it to sense the
2019  * tape.  If that doesn't work, try 512-byte fixed blocks.  If that doesn't
2020  * work, as a last resort, try variable- length blocks.  The result will be
2021  * the ability to do an accurate st_mode_sense.
2022  *
2023  * We know we can do a rewind because we just did a load, which implies rewind.
2024  * Rewind seems preferable to space backward if we have a virgin tape.
2025  *
2026  * The rest of the code for this quirk is in ILI processing and BLANK CHECK
2027  * error processing, both part of st_interpret_sense.
2028  */
2029 int
2030 st_touch_tape(struct st_softc *st)
2031 {
2032 	char *buf = NULL;
2033 	int readsize, maxblksize = 1024;
2034 	int error = 0;
2035 
2036 	if ((error = st_mode_sense(st, 0)) != 0)
2037 		goto done;
2038 	buf = dma_alloc(maxblksize, PR_NOWAIT);
2039 	if (buf == NULL) {
2040 		error = ENOMEM;
2041 		goto done;
2042 	}
2043 
2044 	st->blksize = 1024;
2045 	do {
2046 		switch (st->blksize) {
2047 		case 512:
2048 		case 1024:
2049 			readsize = st->blksize;
2050 			SET(st->flags, ST_FIXEDBLOCKS);
2051 			break;
2052 		default:
2053 			readsize = 1;
2054 			CLR(st->flags, ST_FIXEDBLOCKS);
2055 		}
2056 		if ((error = st_mode_select(st, 0)) != 0)
2057 			goto done;
2058 		st_read(st, buf, readsize, SCSI_SILENT);	/* XXX */
2059 		if ((error = st_rewind(st, 0, 0)) != 0)
2060 			goto done;
2061 	} while (readsize != 1 && readsize > st->blksize);
2062 done:
2063 	dma_free(buf, maxblksize);
2064 	return error;
2065 }
2066