xref: /netbsd-src/sys/dev/scsipi/st.c (revision deb6f0161a9109e7de9b519dc8dfb9478668dcdd)
1 /*	$NetBSD: st.c,v 1.234 2018/03/24 08:08:19 mlelstv Exp $ */
2 
3 /*-
4  * Copyright (c) 1998, 2004 The NetBSD Foundation, Inc.
5  * All rights reserved.
6  *
7  * This code is derived from software contributed to The NetBSD Foundation
8  * by Charles M. Hannum.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29  * 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  * A lot of rewhacking done by mjacob (mjacob@nas.nasa.gov).
50  */
51 
52 #include <sys/cdefs.h>
53 __KERNEL_RCSID(0, "$NetBSD: st.c,v 1.234 2018/03/24 08:08:19 mlelstv Exp $");
54 
55 #ifdef _KERNEL_OPT
56 #include "opt_scsi.h"
57 #endif
58 
59 #include <sys/param.h>
60 #include <sys/systm.h>
61 #include <sys/fcntl.h>
62 #include <sys/errno.h>
63 #include <sys/ioctl.h>
64 #include <sys/malloc.h>
65 #include <sys/buf.h>
66 #include <sys/bufq.h>
67 #include <sys/proc.h>
68 #include <sys/mtio.h>
69 #include <sys/device.h>
70 #include <sys/conf.h>
71 #include <sys/kernel.h>
72 #include <sys/vnode.h>
73 #include <sys/iostat.h>
74 #include <sys/sysctl.h>
75 
76 #include <dev/scsipi/scsi_spc.h>
77 #include <dev/scsipi/scsipi_all.h>
78 #include <dev/scsipi/scsi_all.h>
79 #include <dev/scsipi/scsi_tape.h>
80 #include <dev/scsipi/scsipiconf.h>
81 #include <dev/scsipi/scsipi_base.h>
82 #include <dev/scsipi/stvar.h>
83 
84 /* Defines for device specific stuff */
85 #define DEF_FIXED_BSIZE  512
86 
87 #define STMODE(z)	( minor(z)       & 0x03)
88 #define STDSTY(z)	((minor(z) >> 2) & 0x03)
89 #define STUNIT(z)	((minor(z) >> 4)       )
90 #define STNMINOR	16
91 
92 #define NORMAL_MODE	0
93 #define NOREW_MODE	1
94 #define EJECT_MODE	2
95 #define CTRL_MODE	3
96 
97 #ifndef		ST_MOUNT_DELAY
98 #define		ST_MOUNT_DELAY		0
99 #endif
100 
101 static dev_type_open(stopen);
102 static dev_type_close(stclose);
103 static dev_type_read(stread);
104 static dev_type_write(stwrite);
105 static dev_type_ioctl(stioctl);
106 static dev_type_strategy(ststrategy);
107 static dev_type_dump(stdump);
108 
109 const struct bdevsw st_bdevsw = {
110 	.d_open = stopen,
111 	.d_close = stclose,
112 	.d_strategy = ststrategy,
113 	.d_ioctl = stioctl,
114 	.d_dump = stdump,
115 	.d_psize = nosize,
116 	.d_discard = nodiscard,
117 	.d_flag = D_TAPE | D_MPSAFE
118 };
119 
120 const struct cdevsw st_cdevsw = {
121 	.d_open = stopen,
122 	.d_close = stclose,
123 	.d_read = stread,
124 	.d_write = stwrite,
125 	.d_ioctl = stioctl,
126 	.d_stop = nostop,
127 	.d_tty = notty,
128 	.d_poll = nopoll,
129 	.d_mmap = nommap,
130 	.d_kqfilter = nokqfilter,
131 	.d_discard = nodiscard,
132 	.d_flag = D_TAPE | D_MPSAFE
133 };
134 
135 /*
136  * Define various devices that we know mis-behave in some way,
137  * and note how they are bad, so we can correct for them
138  */
139 
140 static const struct st_quirk_inquiry_pattern st_quirk_patterns[] = {
141 	{{T_SEQUENTIAL, T_REMOV,
142 	 "        ", "                ", "    "}, {0, 0, {
143 		{ST_Q_FORCE_BLKSIZE, 512, 0},		/* minor 0-3 */
144 		{ST_Q_FORCE_BLKSIZE, 512, QIC_24},	/* minor 4-7 */
145 		{ST_Q_FORCE_BLKSIZE, 0, HALFINCH_1600},	/* minor 8-11 */
146 		{ST_Q_FORCE_BLKSIZE, 0, HALFINCH_6250}	/* minor 12-15 */
147 	}}},
148 	{{T_SEQUENTIAL, T_REMOV,
149 	 "TANDBERG", " TDC 3600       ", ""},     {0, 12, {
150 		{0, 0, 0},				/* minor 0-3 */
151 		{ST_Q_FORCE_BLKSIZE, 0, QIC_525},	/* minor 4-7 */
152 		{0, 0, QIC_150},			/* minor 8-11 */
153 		{0, 0, QIC_120}				/* minor 12-15 */
154 	}}},
155  	{{T_SEQUENTIAL, T_REMOV,
156  	 "TANDBERG", " TDC 3800       ", ""},     {0, 0, {
157 		{ST_Q_FORCE_BLKSIZE, 512, 0},		/* minor 0-3 */
158 		{0, 0, QIC_525},			/* minor 4-7 */
159 		{0, 0, QIC_150},			/* minor 8-11 */
160 		{0, 0, QIC_120}				/* minor 12-15 */
161 	}}},
162 	{{T_SEQUENTIAL, T_REMOV,
163 	  "TANDBERG", " SLR5 4/8GB     ", ""},     {0, 0, {
164 		{ST_Q_FORCE_BLKSIZE, 1024, 0},		/* minor 0-3 */
165 		{0, 0, 0},				/* minor 4-7 */
166 		{0, 0, 0},				/* minor 8-11 */
167 		{0, 0, 0}				/* minor 12-15 */
168 	}}},
169 	/*
170 	 * lacking a manual for the 4200, it's not clear what the
171 	 * specific density codes should be- the device is a 2.5GB
172 	 * capable QIC drive, those density codes aren't readily
173 	 * availabel. The 'default' will just have to do.
174 	 */
175  	{{T_SEQUENTIAL, T_REMOV,
176  	 "TANDBERG", " TDC 4200       ", ""},     {0, 0, {
177 		{ST_Q_FORCE_BLKSIZE, 512, 0},		/* minor 0-3 */
178 		{0, 0, QIC_525},			/* minor 4-7 */
179 		{0, 0, QIC_150},			/* minor 8-11 */
180 		{0, 0, QIC_120}				/* minor 12-15 */
181 	}}},
182 	/*
183 	 * At least -005 and -007 need this.  I'll assume they all do unless I
184 	 * hear otherwise.  - mycroft, 31MAR1994
185 	 */
186 	{{T_SEQUENTIAL, T_REMOV,
187 	 "ARCHIVE ", "VIPER 2525 25462", ""},     {0, 0, {
188 		{ST_Q_SENSE_HELP, 0, 0},		/* minor 0-3 */
189 		{ST_Q_SENSE_HELP, 0, QIC_525},		/* minor 4-7 */
190 		{0, 0, QIC_150},			/* minor 8-11 */
191 		{0, 0, QIC_120}				/* minor 12-15 */
192 	}}},
193 	/*
194 	 * One user reports that this works for his tape drive.  It probably
195 	 * needs more work.  - mycroft, 09APR1994
196 	 */
197 	{{T_SEQUENTIAL, T_REMOV,
198 	 "SANKYO  ", "CP525           ", ""},    {0, 0, {
199 		{ST_Q_FORCE_BLKSIZE, 512, 0},		/* minor 0-3 */
200 		{ST_Q_FORCE_BLKSIZE, 512, QIC_525},	/* minor 4-7 */
201 		{0, 0, QIC_150},			/* minor 8-11 */
202 		{0, 0, QIC_120}				/* minor 12-15 */
203 	}}},
204 	{{T_SEQUENTIAL, T_REMOV,
205 	 "ANRITSU ", "DMT780          ", ""},     {0, 0, {
206 		{ST_Q_FORCE_BLKSIZE, 512, 0},		/* minor 0-3 */
207 		{ST_Q_FORCE_BLKSIZE, 512, QIC_525},	/* minor 4-7 */
208 		{0, 0, QIC_150},			/* minor 8-11 */
209 		{0, 0, QIC_120}				/* minor 12-15 */
210 	}}},
211 	{{T_SEQUENTIAL, T_REMOV,
212 	 "ARCHIVE ", "VIPER 150  21247", ""},     {ST_Q_ERASE_NOIMM, 12, {
213 		{ST_Q_SENSE_HELP, 0, 0},		/* minor 0-3 */
214 		{0, 0, QIC_150},			/* minor 4-7 */
215 		{0, 0, QIC_120},			/* minor 8-11 */
216 		{0, 0, QIC_24}				/* minor 12-15 */
217 	}}},
218 	{{T_SEQUENTIAL, T_REMOV,
219 	 "ARCHIVE ", "VIPER 150  21531", ""},     {ST_Q_ERASE_NOIMM, 12, {
220 		{ST_Q_SENSE_HELP, 0, 0},		/* minor 0-3 */
221 		{0, 0, QIC_150},			/* minor 4-7 */
222 		{0, 0, QIC_120},			/* minor 8-11 */
223 		{0, 0, QIC_24}				/* minor 12-15 */
224 	}}},
225 	{{T_SEQUENTIAL, T_REMOV,
226 	 "WANGTEK ", "5099ES SCSI", ""},          {0, 0, {
227 		{ST_Q_FORCE_BLKSIZE, 512, 0},		/* minor 0-3 */
228 		{0, 0, QIC_11},				/* minor 4-7 */
229 		{0, 0, QIC_24},				/* minor 8-11 */
230 		{0, 0, QIC_24}				/* minor 12-15 */
231 	}}},
232 	{{T_SEQUENTIAL, T_REMOV,
233 	 "WANGTEK ", "5150ES SCSI", ""},          {0, 0, {
234 		{ST_Q_FORCE_BLKSIZE, 512, 0},		/* minor 0-3 */
235 		{0, 0, QIC_24},				/* minor 4-7 */
236 		{0, 0, QIC_120},			/* minor 8-11 */
237 		{0, 0, QIC_150}				/* minor 12-15 */
238 	}}},
239 	{{T_SEQUENTIAL, T_REMOV,
240 	 "WANGTEK ", "5525ES SCSI REV7", ""},     {0, 0, {
241 		{0, 0, 0},				/* minor 0-3 */
242 		{ST_Q_BLKSIZE, 0, QIC_525},		/* minor 4-7 */
243 		{0, 0, QIC_150},			/* minor 8-11 */
244 		{0, 0, QIC_120}				/* minor 12-15 */
245 	}}},
246 	{{T_SEQUENTIAL, T_REMOV,
247 	 "WangDAT ", "Model 1300      ", ""},     {0, 0, {
248 		{0, 0, 0},				/* minor 0-3 */
249 		{ST_Q_FORCE_BLKSIZE, 512, DDS},		/* minor 4-7 */
250 		{ST_Q_FORCE_BLKSIZE, 1024, DDS},	/* minor 8-11 */
251 		{ST_Q_FORCE_BLKSIZE, 0, DDS}		/* minor 12-15 */
252 	}}},
253 	{{T_SEQUENTIAL, T_REMOV,
254 	 "EXABYTE ", "EXB-8200        ", "263H"}, {0, 5, {
255 		{0, 0, 0},				/* minor 0-3 */
256 		{0, 0, 0},				/* minor 4-7 */
257 		{0, 0, 0},				/* minor 8-11 */
258 		{0, 0, 0}				/* minor 12-15 */
259 	}}},
260 	{{T_SEQUENTIAL, T_REMOV,
261 	 "STK",      "9490",             ""},
262 				{ST_Q_FORCE_BLKSIZE, 0, {
263 		{0, 0, 0},				/* minor 0-3 */
264 		{0, 0, 0},				/* minor 4-7 */
265 		{0, 0, 0},				/* minor 8-11 */
266 		{0, 0, 0}				/* minor 12-15 */
267 	}}},
268 	{{T_SEQUENTIAL, T_REMOV,
269 	 "STK",      "SD-3",             ""},
270 				{ST_Q_FORCE_BLKSIZE, 0, {
271 		{0, 0, 0},				/* minor 0-3 */
272 		{0, 0, 0},				/* minor 4-7 */
273 		{0, 0, 0},				/* minor 8-11 */
274 		{0, 0, 0}				/* minor 12-15 */
275 	}}},
276 	{{T_SEQUENTIAL, T_REMOV,
277 	 "IBM",      "03590",            ""},     {ST_Q_IGNORE_LOADS, 0, {
278 		{0, 0, 0},				/* minor 0-3 */
279 		{0, 0, 0},				/* minor 4-7 */
280 		{0, 0, 0},				/* minor 8-11 */
281 		{0, 0, 0}				/* minor 12-15 */
282 	}}},
283 	{{T_SEQUENTIAL, T_REMOV,
284 	 "HP      ", "T4000s          ", ""},     {ST_Q_UNIMODAL, 0, {
285 		{0, 0, QIC_3095},			/* minor 0-3 */
286 		{0, 0, QIC_3095},			/* minor 4-7 */
287 		{0, 0, QIC_3095},			/* minor 8-11 */
288 		{0, 0, QIC_3095},			/* minor 12-15 */
289 	}}},
290 #if 0
291 	{{T_SEQUENTIAL, T_REMOV,
292 	 "EXABYTE ", "EXB-8200        ", ""},     {0, 12, {
293 		{0, 0, 0},				/* minor 0-3 */
294 		{0, 0, 0},				/* minor 4-7 */
295 		{0, 0, 0},				/* minor 8-11 */
296 		{0, 0, 0}				/* minor 12-15 */
297 	}}},
298 #endif
299 	{{T_SEQUENTIAL, T_REMOV,
300 	 "TEAC    ", "MT-2ST/N50      ", ""},     {ST_Q_IGNORE_LOADS, 0, {
301 		{0, 0, 0},			        /* minor 0-3 */
302 		{0, 0, 0},			        /* minor 4-7 */
303 		{0, 0, 0},			        /* minor 8-11 */
304 		{0, 0, 0}			        /* minor 12-15 */
305 	}}},
306 	{{T_SEQUENTIAL, T_REMOV,
307 	 "OnStream", "ADR50 Drive", ""},	  {ST_Q_UNIMODAL, 0, {
308 		{ST_Q_FORCE_BLKSIZE, 512, 0},	        /* minor 0-3 */
309 		{ST_Q_FORCE_BLKSIZE, 512, 0},	        /* minor 4-7 */
310 		{ST_Q_FORCE_BLKSIZE, 512, 0},	        /* minor 8-11 */
311 		{ST_Q_FORCE_BLKSIZE, 512, 0},	        /* minor 12-15 */
312 	}}},
313 	{{T_SEQUENTIAL, T_REMOV,
314 	 "OnStream DI-30",      "",   "1.0"},  {ST_Q_NOFILEMARKS, 0, {
315 		{0, 0, 0},                              /* minor 0-3 */
316 		{0, 0, 0},                              /* minor 4-7 */
317 		{0, 0, 0},                              /* minor 8-11 */
318 		{0, 0, 0}                               /* minor 12-15 */
319 	}}},
320 	{{T_SEQUENTIAL, T_REMOV,
321 	 "NCR H621", "0-STD-03-46F880 ", ""},     {ST_Q_NOPREVENT, 0, {
322 		{0, 0, 0},			       /* minor 0-3 */
323 		{0, 0, 0},			       /* minor 4-7 */
324 		{0, 0, 0},			       /* minor 8-11 */
325 		{0, 0, 0}			       /* minor 12-15 */
326 	}}},
327 	{{T_SEQUENTIAL, T_REMOV,
328 	 "Seagate STT3401A", "hp0atxa", ""},	{0, 0, {
329 		{ST_Q_FORCE_BLKSIZE, 512, 0},		/* minor 0-3 */
330 		{ST_Q_FORCE_BLKSIZE, 1024, 0},		/* minor 4-7 */
331 		{ST_Q_FORCE_BLKSIZE, 512, 0},		/* minor 8-11 */
332 		{ST_Q_FORCE_BLKSIZE, 512, 0}		/* minor 12-15 */
333 	}}},
334 };
335 
336 #define NOEJECT 0
337 #define EJECT 1
338 
339 static void	st_identify_drive(struct st_softc *,
340 		    struct scsipi_inquiry_pattern *);
341 static void	st_loadquirks(struct st_softc *);
342 static int	st_mount_tape(dev_t, int);
343 static void	st_unmount(struct st_softc *, boolean);
344 static int	st_decide_mode(struct st_softc *, boolean);
345 static void	ststart(struct scsipi_periph *);
346 static int	ststart1(struct scsipi_periph *, struct buf *);
347 static void	strestart(void *);
348 static void	stdone(struct scsipi_xfer *, int);
349 static int	st_read(struct st_softc *, char *, int, int);
350 static int	st_space(struct st_softc *, int, u_int, int);
351 static int	st_write_filemarks(struct st_softc *, int, int);
352 static int	st_check_eod(struct st_softc *, boolean, int *, int);
353 static int	st_load(struct st_softc *, u_int, int);
354 static int	st_rewind(struct st_softc *, u_int, int);
355 static int	st_interpret_sense(struct scsipi_xfer *);
356 static int	st_touch_tape(struct st_softc *);
357 static int	st_erase(struct st_softc *, int full, int flags);
358 static int	st_rdpos(struct st_softc *, int, uint32_t *);
359 static int	st_setpos(struct st_softc *, int, uint32_t *);
360 
361 static const struct scsipi_periphsw st_switch = {
362 	st_interpret_sense,
363 	ststart,
364 	NULL,
365 	stdone
366 };
367 
368 #if defined(ST_ENABLE_EARLYWARN)
369 #define	ST_INIT_FLAGS	ST_EARLYWARN
370 #else
371 #define	ST_INIT_FLAGS	0
372 #endif
373 
374 /*
375  * The routine called by the low level scsi routine when it discovers
376  * A device suitable for this driver
377  */
378 void
379 stattach(device_t parent, device_t self, void *aux)
380 {
381 	struct st_softc *st = device_private(self);
382 	struct scsipibus_attach_args *sa = aux;
383 	struct scsipi_periph *periph = sa->sa_periph;
384 
385 	SC_DEBUG(periph, SCSIPI_DB2, ("stattach: "));
386 	st->sc_dev = self;
387 
388 	/* Store information needed to contact our base driver */
389 	st->sc_periph = periph;
390 	periph->periph_dev = st->sc_dev;
391 	periph->periph_switch = &st_switch;
392 
393 	/* Set initial flags  */
394 	st->flags = ST_INIT_FLAGS;
395 
396 	/* Set up the buf queues for this device */
397 	bufq_alloc(&st->buf_queue, "fcfs", 0);
398 	bufq_alloc(&st->buf_defer, "fcfs", 0);
399 	callout_init(&st->sc_callout, 0);
400 	mutex_init(&st->sc_iolock, MUTEX_DEFAULT, IPL_VM);
401 
402 	/*
403 	 * Check if the drive is a known criminal and take
404 	 * Any steps needed to bring it into line
405 	 */
406 	st_identify_drive(st, &sa->sa_inqbuf);
407 	aprint_naive("\n");
408 	aprint_normal("\n");
409 	/* Use the subdriver to request information regarding the drive.  */
410 	aprint_normal_dev(self, "%s", st->quirkdata ? "quirks apply, " : "");
411 	if (scsipi_test_unit_ready(periph,
412 	    XS_CTL_DISCOVERY | XS_CTL_SILENT | XS_CTL_IGNORE_MEDIA_CHANGE) ||
413 	    st->ops(st, ST_OPS_MODESENSE,
414 	    XS_CTL_DISCOVERY | XS_CTL_SILENT | XS_CTL_IGNORE_MEDIA_CHANGE))
415 		aprint_normal("drive empty\n");
416 	else {
417 		aprint_normal("density code %d, ", st->media_density);
418 		if (st->media_blksize > 0)
419 			aprint_normal("%d-byte", st->media_blksize);
420 		else
421 			aprint_normal("variable");
422 		aprint_normal(" blocks, write-%s\n",
423 		    (st->flags & ST_READONLY) ? "protected" : "enabled");
424 	}
425 
426 	st->stats = iostat_alloc(IOSTAT_TAPE, parent,
427 	    device_xname(st->sc_dev));
428 
429 	rnd_attach_source(&st->rnd_source, device_xname(st->sc_dev),
430 	    RND_TYPE_TAPE, RND_FLAG_DEFAULT);
431 }
432 
433 int
434 stdetach(device_t self, int flags)
435 {
436 	struct st_softc *st = device_private(self);
437 	struct scsipi_periph *periph = st->sc_periph;
438 	struct scsipi_channel *chan = periph->periph_channel;
439 	int bmaj, cmaj, mn;
440 
441 	/* locate the major number */
442 	bmaj = bdevsw_lookup_major(&st_bdevsw);
443 	cmaj = cdevsw_lookup_major(&st_cdevsw);
444 
445 	/* kill any pending restart */
446 	callout_halt(&st->sc_callout, NULL);
447 
448 	mutex_enter(chan_mtx(chan));
449 
450 	/* Kill off any queued buffers. */
451 	bufq_drain(st->buf_defer);
452 	bufq_drain(st->buf_queue);
453 
454 	/* Kill off any pending commands. */
455 	scsipi_kill_pending(st->sc_periph);
456 
457 	mutex_exit(chan_mtx(chan));
458 
459 	bufq_free(st->buf_defer);
460 	bufq_free(st->buf_queue);
461 	mutex_destroy(&st->sc_iolock);
462 
463 	/* Nuke the vnodes for any open instances */
464 	mn = STUNIT(device_unit(self));
465 	vdevgone(bmaj, mn, mn+STNMINOR-1, VBLK);
466 	vdevgone(cmaj, mn, mn+STNMINOR-1, VCHR);
467 
468 	iostat_free(st->stats);
469 
470 	/* Unhook the entropy source. */
471 	rnd_detach_source(&st->rnd_source);
472 
473 	return 0;
474 }
475 
476 /*
477  * Use the inquiry routine in 'scsi_base' to get drive info so we can
478  * Further tailor our behaviour.
479  */
480 static void
481 st_identify_drive(struct st_softc *st, struct scsipi_inquiry_pattern *inqbuf)
482 {
483 	const struct st_quirk_inquiry_pattern *finger;
484 	int priority;
485 
486 	finger = scsipi_inqmatch(inqbuf,
487 	    st_quirk_patterns,
488 	    sizeof(st_quirk_patterns) / sizeof(st_quirk_patterns[0]),
489 	    sizeof(st_quirk_patterns[0]), &priority);
490 	if (priority != 0) {
491 		st->quirkdata = &finger->quirkdata;
492 		st->drive_quirks = finger->quirkdata.quirks;
493 		st->quirks = finger->quirkdata.quirks;	/* start value */
494 		st->page_0_size = finger->quirkdata.page_0_size;
495 		KASSERT(st->page_0_size <= MAX_PAGE_0_SIZE);
496 		st_loadquirks(st);
497 	}
498 }
499 
500 /*
501  * initialise the subdevices to the default (QUIRK) state.
502  * this will remove any setting made by the system operator or previous
503  * operations.
504  */
505 static void
506 st_loadquirks(struct st_softc *st)
507 {
508 	const struct	modes *mode;
509 	struct	modes *mode2;
510 	int i;
511 
512 	mode = st->quirkdata->modes;
513 	mode2 = st->modes;
514 	for (i = 0; i < 4; i++) {
515 		memset(mode2, 0, sizeof(struct modes));
516 		st->modeflags[i] &= ~(BLKSIZE_SET_BY_QUIRK |
517 		    DENSITY_SET_BY_QUIRK | BLKSIZE_SET_BY_USER |
518 		    DENSITY_SET_BY_USER);
519 		if ((mode->quirks | st->drive_quirks) & ST_Q_FORCE_BLKSIZE) {
520 			mode2->blksize = mode->blksize;
521 			st->modeflags[i] |= BLKSIZE_SET_BY_QUIRK;
522 		}
523 		if (mode->density) {
524 			mode2->density = mode->density;
525 			st->modeflags[i] |= DENSITY_SET_BY_QUIRK;
526 		}
527 		mode2->quirks |= mode->quirks;
528 		mode++;
529 		mode2++;
530 	}
531 }
532 
533 /* open the device. */
534 static int
535 stopen(dev_t dev, int flags, int mode, struct lwp *l)
536 {
537 	u_int stmode, dsty;
538 	int error, sflags, unit, tries, ntries;
539 	struct st_softc *st;
540 	struct scsipi_periph *periph;
541 	struct scsipi_adapter *adapt;
542 
543 	unit = STUNIT(dev);
544 	st = device_lookup_private(&st_cd, unit);
545 	if (st == NULL)
546 		return ENXIO;
547 
548 	stmode = STMODE(dev);
549 	dsty = STDSTY(dev);
550 
551 	periph = st->sc_periph;
552 	adapt = periph->periph_channel->chan_adapter;
553 
554 	SC_DEBUG(periph, SCSIPI_DB1,
555 	    ("open: dev=0x%"PRIx64" (unit %d (of %d))\n", dev, unit,
556 	    st_cd.cd_ndevs));
557 
558 	/* Only allow one at a time */
559 	if (periph->periph_flags & PERIPH_OPEN) {
560 		aprint_error_dev(st->sc_dev, "already open\n");
561 		return EBUSY;
562 	}
563 
564 	if ((error = scsipi_adapter_addref(adapt)) != 0)
565 		return error;
566 
567 	/* clear any latched errors. */
568 	st->mt_resid = 0;
569 	st->mt_erreg = 0;
570 	st->asc = 0;
571 	st->ascq = 0;
572 
573 	/*
574 	 * Catch any unit attention errors. Be silent about this
575 	 * unless we're already mounted. We ignore media change
576 	 * if we're in control mode or not mounted yet.
577 	 */
578 	if ((st->flags & ST_MOUNTED) == 0 || stmode == CTRL_MODE) {
579 #ifdef SCSIDEBUG
580 		sflags = XS_CTL_IGNORE_MEDIA_CHANGE;
581 #else
582 		sflags = XS_CTL_SILENT|XS_CTL_IGNORE_MEDIA_CHANGE;
583 #endif
584 	} else
585 		sflags = 0;
586 
587 	/*
588 	 * If we're already mounted or we aren't configured for
589 	 * a mount delay, only try a test unit ready once. Otherwise,
590 	 * try up to ST_MOUNT_DELAY times with a rest interval of
591 	 * one second between each try.
592 	 */
593 	if ((st->flags & ST_MOUNTED) || ST_MOUNT_DELAY == 0)
594 		ntries = 1;
595 	else
596 		ntries = ST_MOUNT_DELAY;
597 
598 	for (error = tries = 0; tries < ntries; tries++) {
599 		int slpintr, oflags;
600 
601 		/*
602 		 * If we had no error, or we're opening the control mode
603 		 * device, we jump out right away.
604 		 */
605 		error = scsipi_test_unit_ready(periph, sflags);
606 		if (error == 0 || stmode == CTRL_MODE)
607 			break;
608 
609 		/*
610 		 * We had an error.
611 		 *
612 		 * If we're already mounted or we aren't configured for
613 		 * a mount delay, or the error isn't a NOT READY error,
614 		 * skip to the error exit now.
615 		 */
616 		if ((st->flags & ST_MOUNTED) || ST_MOUNT_DELAY == 0 ||
617 		    (st->mt_key != SKEY_NOT_READY)) {
618 			device_printf(st->sc_dev, "mount error (key=%d)\n",
619 				st->mt_key);
620 			goto bad;
621 		}
622 
623 		/* clear any latched errors. */
624 		st->mt_resid = 0;
625 		st->mt_erreg = 0;
626 		st->asc = 0;
627 		st->ascq = 0;
628 
629 		/*
630 		 * Fake that we have the device open so
631 		 * we block other apps from getting in.
632 		 */
633 		oflags = periph->periph_flags;
634 		periph->periph_flags |= PERIPH_OPEN;
635 
636 		slpintr = kpause("stload", true, hz, NULL);
637 
638 		periph->periph_flags = oflags;	/* restore flags */
639 		if (slpintr != 0 && slpintr != EWOULDBLOCK) {
640 			device_printf(st->sc_dev, "load interrupted\n");
641 			goto bad;
642 		}
643 	}
644 
645 	/*
646 	 * If the mode is 3 (e.g. minor = 3,7,11,15) then the device has
647 	 * been opened to set defaults and perform other, usually non-I/O
648 	 * related, operations. In this case, do a quick check to see
649 	 * whether the unit actually had a tape loaded (this will be known
650 	 * as to whether or not we got a NOT READY for the above
651 	 * unit attention). If a tape is there, go do a mount sequence.
652 	 */
653 	if (stmode == CTRL_MODE &&
654 	    st->mt_key != SKEY_NO_SENSE &&
655 	    st->mt_key != SKEY_UNIT_ATTENTION) {
656 		periph->periph_flags |= PERIPH_OPEN;
657 		return 0;
658 	}
659 
660 	/*
661 	 * If we get this far and had an error set, that means we failed
662 	 * to pass the 'test unit ready' test for the non-controlmode device,
663 	 * so we bounce the open.
664 	 */
665 	if (error)
666 		return error;
667 
668 	/* Else, we're now committed to saying we're open. */
669 	periph->periph_flags |= PERIPH_OPEN; /* unit attn are now errors */
670 
671 	/*
672 	 * If it's a different mode, or if the media has been
673 	 * invalidated, unmount the tape from the previous
674 	 * session but continue with open processing
675 	 */
676 	if (st->last_dsty != dsty ||
677 	    (periph->periph_flags & PERIPH_MEDIA_LOADED) == 0)
678 		st_unmount(st, NOEJECT);
679 
680 	/*
681 	 * If we are not mounted, then we should start a new
682 	 * mount session.
683 	 */
684 	if (!(st->flags & ST_MOUNTED)) {
685 		if ((error = st_mount_tape(dev, flags)) != 0)
686 			goto bad;
687 		st->last_dsty = dsty;
688 	}
689 	if (!(st->quirks & ST_Q_NOPREVENT)) {
690 		scsipi_prevent(periph, SPAMR_PREVENT_DT,
691 		    XS_CTL_IGNORE_ILLEGAL_REQUEST | XS_CTL_IGNORE_NOT_READY);
692 	}
693 
694 	SC_DEBUG(periph, SCSIPI_DB2, ("open complete\n"));
695 	return 0;
696 
697 bad:
698 	st_unmount(st, NOEJECT);
699 	scsipi_adapter_delref(adapt);
700 	periph->periph_flags &= ~PERIPH_OPEN;
701 	return error;
702 }
703 
704 static int
705 stclose(dev_t dev, int flags, int mode, struct lwp *l)
706 {
707 	int stxx, error = 0;
708 	struct st_softc *st = device_lookup_private(&st_cd, STUNIT(dev));
709 	struct scsipi_periph *periph = st->sc_periph;
710 	struct scsipi_adapter *adapt = periph->periph_channel->chan_adapter;
711 
712 	SC_DEBUG(st->sc_periph, SCSIPI_DB1, ("closing\n"));
713 
714 	/*
715 	 * Make sure that a tape opened in write-only mode will have
716 	 * file marks written on it when closed, even if not written to.
717 	 *
718 	 * This is for SUN compatibility. Actually, the Sun way of
719 	 * things is to:
720 	 *
721 	 *	only write filemarks if there are fmks to be written and
722 	 *   		- open for write (possibly read/write)
723 	 *		- the last operation was a write
724 	 * 	or:
725 	 *		- opened for wronly
726 	 *		- no data was written (including filemarks)
727 	 */
728 
729 	stxx = st->flags & (ST_WRITTEN | ST_FM_WRITTEN);
730 	if (((flags & FWRITE) && stxx == ST_WRITTEN) ||
731 	    ((flags & O_ACCMODE) == FWRITE && stxx == 0)) {
732 		int nm;
733 		error = st_check_eod(st, FALSE, &nm, 0);
734 	}
735 
736 	/* Allow robots to eject tape if needed.  */
737 	scsipi_prevent(periph, SPAMR_ALLOW,
738 	    XS_CTL_IGNORE_ILLEGAL_REQUEST | XS_CTL_IGNORE_NOT_READY);
739 
740 	switch (STMODE(dev)) {
741 	case NORMAL_MODE:
742 		st_unmount(st, NOEJECT);
743 		break;
744 	case NOREW_MODE:
745 	case CTRL_MODE:
746 		/*
747 		 * Leave mounted unless media seems to have been removed.
748 		 *
749 		 * Otherwise, if we're to terminate a tape with more than one
750 		 * filemark [ and because we're not rewinding here ], backspace
751 		 * one filemark so that later appends will see an unbroken
752 		 * sequence of:
753 		 *
754 		 *	file - FMK - file - FMK ... file - FMK FMK (EOM)
755 		 */
756 		if ((periph->periph_flags & PERIPH_MEDIA_LOADED) == 0) {
757 			st_unmount(st, NOEJECT);
758 		} else if (error == 0) {
759 			/*
760 			 * ST_WRITTEN was preserved from above.
761 			 *
762 			 * All we need to know here is:
763 			 *
764 			 *	Were we writing this tape and was the last
765 			 *	operation a write?
766 			 *
767 			 *	Are there supposed to be 2FM at EOD?
768 			 *
769 			 * If both statements are true, then we backspace
770 			 * one filemark.
771 			 */
772 			stxx |= (st->flags & ST_2FM_AT_EOD);
773 			if ((flags & FWRITE) != 0 &&
774 			    (stxx == (ST_2FM_AT_EOD|ST_WRITTEN))) {
775 				error = st_space(st, -1, SP_FILEMARKS, 0);
776 			}
777 		}
778 		break;
779 	case EJECT_MODE:
780 		st_unmount(st, EJECT);
781 		break;
782 	}
783 
784 	scsipi_wait_drain(periph);
785 
786 	scsipi_adapter_delref(adapt);
787 	periph->periph_flags &= ~PERIPH_OPEN;
788 
789 	return error;
790 }
791 
792 /*
793  * Start a new mount session.
794  * Copy in all the default parameters from the selected device mode.
795  * and try guess any that seem to be defaulted.
796  */
797 static int
798 st_mount_tape(dev_t dev, int flags)
799 {
800 	int unit;
801 	u_int dsty;
802 	struct st_softc *st;
803 	struct scsipi_periph *periph;
804 	int error = 0;
805 
806 	unit = STUNIT(dev);
807 	dsty = STDSTY(dev);
808 	st = device_lookup_private(&st_cd, unit);
809 	periph = st->sc_periph;
810 
811 	if (st->flags & ST_MOUNTED)
812 		return 0;
813 
814 	SC_DEBUG(periph, SCSIPI_DB1, ("mounting\n "));
815 	st->flags |= ST_NEW_MOUNT;
816 	st->quirks = st->drive_quirks | st->modes[dsty].quirks;
817 	/*
818 	 * If the media is new, then make sure we give it a chance to
819 	 * to do a 'load' instruction.  (We assume it is new.)
820 	 */
821 	if ((error = st_load(st, LD_LOAD, XS_CTL_SILENT)) != 0)
822 		return error;
823 	/*
824 	 * Throw another dummy instruction to catch
825 	 * 'Unit attention' errors. Many drives give
826 	 * these after doing a Load instruction (with
827 	 * the MEDIUM MAY HAVE CHANGED asc/ascq).
828 	 */
829 	scsipi_test_unit_ready(periph, XS_CTL_SILENT);	/* XXX */
830 
831 	/*
832 	 * Some devices can't tell you much until they have been
833 	 * asked to look at the media. This quirk does this.
834 	 */
835 	if (st->quirks & ST_Q_SENSE_HELP)
836 		if ((error = st_touch_tape(st)) != 0)
837 			return error;
838 	/*
839 	 * Load the physical device parameters
840 	 * loads: blkmin, blkmax
841 	 */
842 	if ((error = st->ops(st, ST_OPS_RBL, 0)) != 0)
843 		return error;
844 	/*
845 	 * Load the media dependent parameters
846 	 * includes: media_blksize,media_density,numblks
847 	 * As we have a tape in, it should be reflected here.
848 	 * If not you may need the "quirk" above.
849 	 */
850 	if ((error = st->ops(st, ST_OPS_MODESENSE, 0)) != 0)
851 		return error;
852 	/*
853 	 * If we have gained a permanent density from somewhere,
854 	 * then use it in preference to the one supplied by
855 	 * default by the driver.
856 	 */
857 	if (st->modeflags[dsty] & (DENSITY_SET_BY_QUIRK | DENSITY_SET_BY_USER))
858 		st->density = st->modes[dsty].density;
859 	else
860 		st->density = st->media_density;
861 	/*
862 	 * If we have gained a permanent blocksize
863 	 * then use it in preference to the one supplied by
864 	 * default by the driver.
865 	 */
866 	st->flags &= ~ST_FIXEDBLOCKS;
867 	if (st->modeflags[dsty] &
868 	    (BLKSIZE_SET_BY_QUIRK | BLKSIZE_SET_BY_USER)) {
869 		st->blksize = st->modes[dsty].blksize;
870 		if (st->blksize)
871 			st->flags |= ST_FIXEDBLOCKS;
872 	} else {
873 		if ((error = st_decide_mode(st, FALSE)) != 0)
874 			return error;
875 	}
876 	if ((error = st->ops(st, ST_OPS_MODESELECT, 0)) != 0) {
877 		/* ATAPI will return ENODEV for this, and this may be OK */
878 		if (error != ENODEV) {
879 			aprint_error_dev(st->sc_dev,
880 			    "cannot set selected mode\n");
881 			return error;
882 		}
883 	}
884 	st->flags &= ~ST_NEW_MOUNT;
885 	st->flags |= ST_MOUNTED;
886 	periph->periph_flags |= PERIPH_MEDIA_LOADED;	/* move earlier? */
887 	st->blkno = st->fileno = (daddr_t) 0;
888 	return 0;
889 }
890 
891 /*
892  * End the present mount session.
893  * Rewind, and optionally eject the tape.
894  * Reset various flags to indicate that all new
895  * operations require another mount operation
896  */
897 static void
898 st_unmount(struct st_softc *st, boolean eject)
899 {
900 	struct scsipi_periph *periph = st->sc_periph;
901 	int nmarks;
902 
903 	if ((st->flags & ST_MOUNTED) == 0)
904 		return;
905 	SC_DEBUG(periph, SCSIPI_DB1, ("unmounting\n"));
906 	st_check_eod(st, FALSE, &nmarks, XS_CTL_IGNORE_NOT_READY);
907 	st_rewind(st, 0, XS_CTL_IGNORE_NOT_READY);
908 
909 	/*
910 	 * Section 9.3.3 of the SCSI specs states that a device shall return
911 	 * the density value specified in the last succesfull MODE SELECT
912 	 * after an unload operation, in case it is not able to
913 	 * automatically determine the density of the new medium.
914 	 *
915 	 * So we instruct the device to use the default density, which will
916 	 * prevent the use of stale density values (in particular,
917 	 * in st_touch_tape().
918 	 */
919 	st->density = 0;
920 	if (st->ops(st, ST_OPS_MODESELECT, 0) != 0) {
921 		aprint_error_dev(st->sc_dev,
922 		    "WARNING: cannot revert to default density\n");
923 	}
924 
925 	if (eject) {
926 		if (!(st->quirks & ST_Q_NOPREVENT)) {
927 			scsipi_prevent(periph, SPAMR_ALLOW,
928 			    XS_CTL_IGNORE_ILLEGAL_REQUEST |
929 			    XS_CTL_IGNORE_NOT_READY);
930 		}
931 		st_load(st, LD_UNLOAD, XS_CTL_IGNORE_NOT_READY);
932 		st->blkno = st->fileno = (daddr_t) -1;
933 	} else {
934 		st->blkno = st->fileno = (daddr_t) 0;
935 	}
936 	st->flags &= ~(ST_MOUNTED | ST_NEW_MOUNT);
937 	periph->periph_flags &= ~PERIPH_MEDIA_LOADED;
938 }
939 
940 /*
941  * Given all we know about the device, media, mode, 'quirks' and
942  * initial operation, make a decision as to how we should be set
943  * to run (regarding blocking and EOD marks)
944  */
945 int
946 st_decide_mode(struct st_softc *st, boolean first_read)
947 {
948 
949 	SC_DEBUG(st->sc_periph, SCSIPI_DB2, ("starting block mode decision\n"));
950 
951 	/*
952 	 * If the drive can only handle fixed-length blocks and only at
953 	 * one size, perhaps we should just do that.
954 	 */
955 	if (st->blkmin && (st->blkmin == st->blkmax)) {
956 		st->flags |= ST_FIXEDBLOCKS;
957 		st->blksize = st->blkmin;
958 		SC_DEBUG(st->sc_periph, SCSIPI_DB3,
959 		    ("blkmin == blkmax of %d\n", st->blkmin));
960 		goto done;
961 	}
962 	/*
963 	 * If the tape density mandates (or even suggests) use of fixed
964 	 * or variable-length blocks, comply.
965 	 */
966 	switch (st->density) {
967 	case HALFINCH_800:
968 	case HALFINCH_1600:
969 	case HALFINCH_6250:
970 	case DDS:
971 		st->flags &= ~ST_FIXEDBLOCKS;
972 		st->blksize = 0;
973 		SC_DEBUG(st->sc_periph, SCSIPI_DB3,
974 		    ("density specified variable\n"));
975 		goto done;
976 	case QIC_11:
977 	case QIC_24:
978 	case QIC_120:
979 	case QIC_150:
980 	case QIC_525:
981 	case QIC_1320:
982 	case QIC_3095:
983 	case QIC_3220:
984 		st->flags |= ST_FIXEDBLOCKS;
985 		if (st->media_blksize > 0)
986 			st->blksize = st->media_blksize;
987 		else
988 			st->blksize = DEF_FIXED_BSIZE;
989 		SC_DEBUG(st->sc_periph, SCSIPI_DB3,
990 		    ("density specified fixed\n"));
991 		goto done;
992 	}
993 	/*
994 	 * If we're about to read the tape, perhaps we should choose
995 	 * fixed or variable-length blocks and block size according to
996 	 * what the drive found on the tape.
997 	 */
998 	if (first_read &&
999 	    (!(st->quirks & ST_Q_BLKSIZE) || (st->media_blksize == 0) ||
1000 	    (st->media_blksize == DEF_FIXED_BSIZE) ||
1001 	    (st->media_blksize == 1024))) {
1002 		if (st->media_blksize > 0)
1003 			st->flags |= ST_FIXEDBLOCKS;
1004 		else
1005 			st->flags &= ~ST_FIXEDBLOCKS;
1006 		st->blksize = st->media_blksize;
1007 		SC_DEBUG(st->sc_periph, SCSIPI_DB3,
1008 		    ("Used media_blksize of %d\n", st->media_blksize));
1009 		goto done;
1010 	}
1011 	/*
1012 	 * We're getting no hints from any direction.  Choose variable-
1013 	 * length blocks arbitrarily.
1014 	 */
1015 	st->flags &= ~ST_FIXEDBLOCKS;
1016 	st->blksize = 0;
1017 	SC_DEBUG(st->sc_periph, SCSIPI_DB3,
1018 	    ("Give up and default to variable mode\n"));
1019 
1020 done:
1021 	/*
1022 	 * Decide whether or not to write two file marks to signify end-
1023 	 * of-data.  Make the decision as a function of density.  If
1024 	 * the decision is not to use a second file mark, the SCSI BLANK
1025 	 * CHECK condition code will be recognized as end-of-data when
1026 	 * first read.
1027 	 * (I think this should be a by-product of fixed/variable..julian)
1028 	 */
1029 	switch (st->density) {
1030 /*      case 8 mm:   What is the SCSI density code for 8 mm, anyway? */
1031 	case QIC_11:
1032 	case QIC_24:
1033 	case QIC_120:
1034 	case QIC_150:
1035 	case QIC_525:
1036 	case QIC_1320:
1037 	case QIC_3095:
1038 	case QIC_3220:
1039 		st->flags &= ~ST_2FM_AT_EOD;
1040 		break;
1041 	default:
1042 		st->flags |= ST_2FM_AT_EOD;
1043 	}
1044 	return 0;
1045 }
1046 
1047 /*
1048  * Actually translate the requested transfer into
1049  * one the physical driver can understand
1050  * The transfer is described by a buf and will include
1051  * only one physical transfer.
1052  */
1053 static void
1054 ststrategy(struct buf *bp)
1055 {
1056 	struct st_softc *st = device_lookup_private(&st_cd, STUNIT(bp->b_dev));
1057 	struct scsipi_periph *periph = st->sc_periph;
1058 	struct scsipi_channel *chan = periph->periph_channel;
1059 
1060 	SC_DEBUG(periph, SCSIPI_DB1,
1061 	    ("ststrategy %d bytes @ blk %" PRId64 "\n", bp->b_bcount,
1062 	        bp->b_blkno));
1063 	/* If it's a null transfer, return immediately */
1064 	if (bp->b_bcount == 0)
1065 		goto abort;
1066 
1067 	/* If offset is negative, error */
1068 	if (bp->b_blkno < 0) {
1069 		bp->b_error = EINVAL;
1070 		goto abort;
1071 	}
1072 
1073 	/* Odd sized request on fixed drives are verboten */
1074 	if (st->flags & ST_FIXEDBLOCKS) {
1075 		if (bp->b_bcount % st->blksize) {
1076 			aprint_error_dev(st->sc_dev, "bad request, must be multiple of %d\n",
1077 			    st->blksize);
1078 			bp->b_error = EIO;
1079 			goto abort;
1080 		}
1081 	}
1082 	/* as are out-of-range requests on variable drives. */
1083 	else if (bp->b_bcount < st->blkmin ||
1084 	    (st->blkmax && bp->b_bcount > st->blkmax)) {
1085 		aprint_error_dev(st->sc_dev, "bad request, must be between %d and %d\n",
1086 		    st->blkmin, st->blkmax);
1087 		bp->b_error = EIO;
1088 		goto abort;
1089 	}
1090 	mutex_enter(chan_mtx(chan));
1091 
1092 	/*
1093 	 * Place it in the queue of activities for this tape
1094 	 * at the end (a bit silly because we only have on user..
1095 	 * (but it could fork()))
1096 	 */
1097 	bufq_put(st->buf_queue, bp);
1098 
1099 	/*
1100 	 * Tell the device to get going on the transfer if it's
1101 	 * not doing anything, otherwise just wait for completion
1102 	 * (All a bit silly if we're only allowing 1 open but..)
1103 	 */
1104 	ststart(periph);
1105 
1106 	mutex_exit(chan_mtx(chan));
1107 	return;
1108 abort:
1109 	/*
1110 	 * Reset the residue because we didn't do anything,
1111 	 * and send the buffer back as done.
1112 	 */
1113 	bp->b_resid = bp->b_bcount;
1114 	biodone(bp);
1115 	return;
1116 }
1117 
1118 /*
1119  * ststart looks to see if there is a buf waiting for the device
1120  * and that the device is not already busy. If the device is busy,
1121  * the request is deferred and retried on the next attempt.
1122  * If both are true, ststart creates a scsi command to perform
1123  * the transfer required.
1124  *
1125  * The transfer request will call scsipi_done on completion,
1126  * which will in turn call this routine again so that the next
1127  * queued transfer is performed. The bufs are queued by the
1128  * strategy routine (ststrategy)
1129  *
1130  * This routine is also called after other non-queued requests
1131  * have been made of the scsi driver, to ensure that the queue
1132  * continues to be drained.
1133  * ststart() is called with channel lock held
1134  */
1135 static int
1136 ststart1(struct scsipi_periph *periph, struct buf *bp)
1137 {
1138 	struct st_softc *st = device_private(periph->periph_dev);
1139         struct scsipi_channel *chan = periph->periph_channel;
1140 	struct scsi_rw_tape cmd;
1141 	struct scsipi_xfer *xs;
1142 	int flags, error;
1143 
1144 	SC_DEBUG(periph, SCSIPI_DB2, ("ststart1 "));
1145 
1146 	mutex_enter(chan_mtx(chan));
1147 
1148 	if (periph->periph_active >= periph->periph_openings) {
1149 		error = EAGAIN;
1150 		goto out;
1151 	}
1152 
1153 	/* if a special awaits, let it proceed first */
1154 	if (periph->periph_flags & PERIPH_WAITING) {
1155 		periph->periph_flags &= ~PERIPH_WAITING;
1156 		cv_broadcast(periph_cv_periph(periph));
1157 		error = EAGAIN;
1158 		goto out;
1159 	}
1160 
1161 	/*
1162 	 * If the device has been unmounted by the user
1163 	 * then throw away all requests until done.
1164 	 */
1165 	if (__predict_false((st->flags & ST_MOUNTED) == 0 ||
1166 	    (periph->periph_flags & PERIPH_MEDIA_LOADED) == 0)) {
1167 		error = EIO;
1168 		goto out;
1169 	}
1170 
1171 	/*
1172 	 * only FIXEDBLOCK devices have pending I/O or space operations.
1173 	 */
1174 	if (st->flags & ST_FIXEDBLOCKS) {
1175 		/*
1176 		 * If we are at a filemark but have not reported it yet
1177 		 * then we should report it now
1178 		 */
1179 		if (st->flags & ST_AT_FILEMARK) {
1180 			if ((bp->b_flags & B_READ) == B_WRITE) {
1181 				/*
1182 				 * Handling of ST_AT_FILEMARK in
1183 				 * st_space will fill in the right file
1184 				 * mark count.
1185 				 * Back up over filemark
1186 				 */
1187 				if (st_space(st, 0, SP_FILEMARKS, 0)) {
1188 					error = EIO;
1189 					goto out;
1190 				}
1191 			} else {
1192 				bp->b_resid = bp->b_bcount;
1193 				error = 0;
1194 				st->flags &= ~ST_AT_FILEMARK;
1195 				goto out;
1196 			}
1197 		}
1198 	}
1199 	/*
1200 	 * If we are at EOM but have not reported it
1201 	 * yet then we should report it now.
1202 	 */
1203 	if (st->flags & (ST_EOM_PENDING|ST_EIO_PENDING)) {
1204 		error = EIO;
1205 		goto out;
1206 	}
1207 
1208 	/* Fill out the scsi command */
1209 	memset(&cmd, 0, sizeof(cmd));
1210 	flags = XS_CTL_NOSLEEP | XS_CTL_ASYNC;
1211 	if ((bp->b_flags & B_READ) == B_WRITE) {
1212 		cmd.opcode = WRITE;
1213 		st->flags &= ~ST_FM_WRITTEN;
1214 		flags |= XS_CTL_DATA_OUT;
1215 	} else {
1216 		cmd.opcode = READ;
1217 		flags |= XS_CTL_DATA_IN;
1218 	}
1219 
1220 	/*
1221 	 * Handle "fixed-block-mode" tape drives by using the
1222 	 * block count instead of the length.
1223 	 */
1224 	if (st->flags & ST_FIXEDBLOCKS) {
1225 		cmd.byte2 |= SRW_FIXED;
1226 		_lto3b(bp->b_bcount / st->blksize, cmd.len);
1227 	} else
1228 		_lto3b(bp->b_bcount, cmd.len);
1229 
1230 	/* Clear 'position updated' indicator */
1231 	st->flags &= ~ST_POSUPDATED;
1232 
1233 	/* go ask the adapter to do all this for us */
1234 	xs = scsipi_make_xs_locked(periph,
1235 	    (struct scsipi_generic *)&cmd, sizeof(cmd),
1236 	    (u_char *)bp->b_data, bp->b_bcount,
1237 	    0, ST_IO_TIME, bp, flags);
1238 	if (__predict_false(xs == NULL)) {
1239 		/*
1240 		 * out of memory. Keep this buffer in the queue, and
1241 		 * retry later.
1242 		 */
1243 		callout_reset(&st->sc_callout, hz / 2, strestart,
1244 		    periph);
1245 		error = EAGAIN;
1246 		goto out;
1247 	}
1248 
1249 	error = scsipi_execute_xs(xs);
1250 	/* with a scsipi_xfer preallocated, scsipi_command can't fail */
1251 	KASSERT(error == 0);
1252 
1253 out:
1254 	mutex_exit(chan_mtx(chan));
1255 
1256 	return error;
1257 }
1258 
1259 static void
1260 ststart(struct scsipi_periph *periph)
1261 {
1262 	struct st_softc *st = device_private(periph->periph_dev);
1263         struct scsipi_channel *chan = periph->periph_channel;
1264 	struct buf *bp;
1265 	int error;
1266 
1267 	SC_DEBUG(periph, SCSIPI_DB2, ("ststart "));
1268 
1269 	mutex_exit(chan_mtx(chan));
1270 	mutex_enter(&st->sc_iolock);
1271 
1272 	while ((bp = bufq_get(st->buf_defer)) != NULL
1273 	       || (bp = bufq_get(st->buf_queue)) != NULL) {
1274 
1275 		iostat_busy(st->stats);
1276 		mutex_exit(&st->sc_iolock);
1277 
1278 		error = ststart1(periph, bp);
1279 
1280 		mutex_enter(&st->sc_iolock);
1281 		if (error != 0)
1282 			iostat_unbusy(st->stats, 0,
1283 			              ((bp->b_flags & B_READ) == B_READ));
1284 		if (error == EAGAIN) {
1285 			bufq_put(st->buf_defer, bp);
1286 			break;
1287 		}
1288 		mutex_exit(&st->sc_iolock);
1289 
1290 		if (error != 0) {
1291 			bp->b_error = error;
1292 			bp->b_resid = bp->b_bcount;
1293 			biodone(bp);
1294 		}
1295 
1296 		mutex_enter(&st->sc_iolock);
1297 	}
1298 
1299 	mutex_exit(&st->sc_iolock);
1300 	mutex_enter(chan_mtx(chan));
1301 }
1302 
1303 static void
1304 strestart(void *v)
1305 {
1306 	struct scsipi_periph *periph = (struct scsipi_periph *)v;
1307 	struct scsipi_channel *chan = periph->periph_channel;
1308 
1309 	mutex_enter(chan_mtx(chan));
1310 	ststart((struct scsipi_periph *)v);
1311 	mutex_exit(chan_mtx(chan));
1312 }
1313 
1314 static void
1315 stdone(struct scsipi_xfer *xs, int error)
1316 {
1317 	struct st_softc *st = device_private(xs->xs_periph->periph_dev);
1318 	struct buf *bp = xs->bp;
1319 
1320 	if (bp) {
1321 		bp->b_error = error;
1322 		bp->b_resid = xs->resid;
1323 		/*
1324 		 * buggy device ? A SDLT320 can report an info
1325 		 * field of 0x3de8000 on a Media Error/Write Error
1326 		 * for this CBD: 0x0a 00 00 80 00 00
1327 		 */
1328 		if (bp->b_resid > bp->b_bcount || bp->b_resid < 0)
1329 			bp->b_resid = bp->b_bcount;
1330 
1331 		mutex_enter(&st->sc_iolock);
1332 
1333 		if ((bp->b_flags & B_READ) == B_WRITE)
1334 			st->flags |= ST_WRITTEN;
1335 		else
1336 			st->flags &= ~ST_WRITTEN;
1337 
1338 		iostat_unbusy(st->stats, bp->b_bcount,
1339 			     ((bp->b_flags & B_READ) == B_READ));
1340 
1341 		if ((st->flags & ST_POSUPDATED) == 0) {
1342 			if (error) {
1343 				st->fileno = st->blkno = -1;
1344 			} else if (st->blkno != -1) {
1345 				if (st->flags & ST_FIXEDBLOCKS)
1346 					st->blkno +=
1347 					    (bp->b_bcount / st->blksize);
1348 				else
1349 					st->blkno++;
1350 			}
1351 		}
1352 
1353 		mutex_exit(&st->sc_iolock);
1354 
1355 		rnd_add_uint32(&st->rnd_source, bp->b_blkno);
1356 
1357 		biodone(bp);
1358 	}
1359 }
1360 
1361 static int
1362 stread(dev_t dev, struct uio *uio, int iomode)
1363 {
1364 	struct st_softc *st = device_lookup_private(&st_cd, STUNIT(dev));
1365 
1366 	return physio(ststrategy, NULL, dev, B_READ,
1367 	    st->sc_periph->periph_channel->chan_adapter->adapt_minphys, uio);
1368 }
1369 
1370 static int
1371 stwrite(dev_t dev, struct uio *uio, int iomode)
1372 {
1373 	struct st_softc *st = device_lookup_private(&st_cd, STUNIT(dev));
1374 
1375 	return physio(ststrategy, NULL, dev, B_WRITE,
1376 	    st->sc_periph->periph_channel->chan_adapter->adapt_minphys, uio);
1377 }
1378 
1379 /*
1380  * Perform special action on behalf of the user;
1381  * knows about the internals of this device
1382  */
1383 static int
1384 stioctl(dev_t dev, u_long cmd, void *arg, int flag, struct lwp *l)
1385 {
1386 	int error = 0;
1387 	int unit;
1388 	int number, nmarks, dsty;
1389 	int flags;
1390 	struct st_softc *st;
1391 	int hold_blksize;
1392 	uint8_t hold_density;
1393 	struct mtop *mt = (struct mtop *) arg;
1394 
1395 	/* Find the device that the user is talking about */
1396 	flags = 0;		/* give error messages, act on errors etc. */
1397 	unit = STUNIT(dev);
1398 	dsty = STDSTY(dev);
1399 	st = device_lookup_private(&st_cd, unit);
1400 	hold_blksize = st->blksize;
1401 	hold_density = st->density;
1402 
1403 	switch ((u_int)cmd) {
1404 	case MTIOCGET: {
1405 		struct mtget *g = (struct mtget *) arg;
1406 		/*
1407 		 * (to get the current state of READONLY)
1408 		 */
1409 		error = st->ops(st, ST_OPS_MODESENSE, XS_CTL_SILENT);
1410 		if (error) {
1411 			/*
1412 			 * Ignore the error if in control mode;
1413 			 * this is mandated by st(4).
1414 			 */
1415 			if (STMODE(dev) != CTRL_MODE)
1416 				break;
1417 			error = 0;
1418 		}
1419 		SC_DEBUG(st->sc_periph, SCSIPI_DB1, ("[ioctl: get status]\n"));
1420 		memset(g, 0, sizeof(struct mtget));
1421 		g->mt_type = MT_ISAR;	/* Ultrix compat *//*? */
1422 		g->mt_blksiz = st->blksize;
1423 		g->mt_density = st->density;
1424 		g->mt_mblksiz[0] = st->modes[0].blksize;
1425 		g->mt_mblksiz[1] = st->modes[1].blksize;
1426 		g->mt_mblksiz[2] = st->modes[2].blksize;
1427 		g->mt_mblksiz[3] = st->modes[3].blksize;
1428 		g->mt_mdensity[0] = st->modes[0].density;
1429 		g->mt_mdensity[1] = st->modes[1].density;
1430 		g->mt_mdensity[2] = st->modes[2].density;
1431 		g->mt_mdensity[3] = st->modes[3].density;
1432 		g->mt_fileno = st->fileno;
1433 		g->mt_blkno = st->blkno;
1434 		if (st->flags & ST_READONLY)
1435 			g->mt_dsreg |= MT_DS_RDONLY;
1436 		if (st->flags & ST_MOUNTED)
1437 			g->mt_dsreg |= MT_DS_MOUNTED;
1438 		g->mt_resid = st->mt_resid;
1439 		g->mt_erreg = st->mt_erreg;
1440 		/*
1441 		 * clear latched errors.
1442 		 */
1443 		st->mt_resid = 0;
1444 		st->mt_erreg = 0;
1445 		st->asc = 0;
1446 		st->ascq = 0;
1447 		break;
1448 	}
1449 	case MTIOCTOP: {
1450 		SC_DEBUG(st->sc_periph, SCSIPI_DB1,
1451 		    ("[ioctl: op=0x%x count=0x%x]\n", mt->mt_op,
1452 			mt->mt_count));
1453 
1454 		/* compat: in U*x it is a short */
1455 		number = mt->mt_count;
1456 		switch ((short) (mt->mt_op)) {
1457 		case MTWEOF:	/* write an end-of-file record */
1458 			error = st_write_filemarks(st, number, flags);
1459 			break;
1460 		case MTBSF:	/* backward space file */
1461 			number = -number;
1462 		case MTFSF:	/* forward space file */
1463 			error = st_check_eod(st, FALSE, &nmarks, flags);
1464 			if (!error)
1465 				error = st_space(st, number - nmarks,
1466 				    SP_FILEMARKS, flags);
1467 			break;
1468 		case MTBSR:	/* backward space record */
1469 			number = -number;
1470 		case MTFSR:	/* forward space record */
1471 			error = st_check_eod(st, true, &nmarks, flags);
1472 			if (!error)
1473 				error = st_space(st, number, SP_BLKS, flags);
1474 			break;
1475 		case MTREW:	/* rewind */
1476 			error = st_rewind(st, 0, flags);
1477 			break;
1478 		case MTOFFL:	/* rewind and put the drive offline */
1479 			st_unmount(st, EJECT);
1480 			break;
1481 		case MTNOP:	/* no operation, sets status only */
1482 			break;
1483 		case MTRETEN:	/* retension the tape */
1484 			error = st_load(st, LD_RETENSION, flags);
1485 			if (!error)
1486 				error = st_load(st, LD_LOAD, flags);
1487 			break;
1488 		case MTEOM:	/* forward space to end of media */
1489 			error = st_check_eod(st, FALSE, &nmarks, flags);
1490 			if (!error)
1491 				error = st_space(st, 1, SP_EOM, flags);
1492 			break;
1493 		case MTCACHE:	/* enable controller cache */
1494 			st->flags &= ~ST_DONTBUFFER;
1495 			goto try_new_value;
1496 		case MTNOCACHE:	/* disable controller cache */
1497 			st->flags |= ST_DONTBUFFER;
1498 			goto try_new_value;
1499 		case MTERASE:	/* erase volume */
1500 			error = st_erase(st, number, flags);
1501 			break;
1502 		case MTSETBSIZ:	/* Set block size for device */
1503 #ifdef	NOTYET
1504 			if (!(st->flags & ST_NEW_MOUNT)) {
1505 				uprintf("re-mount tape before changing "
1506 				    "blocksize");
1507 				error = EINVAL;
1508 				break;
1509 			}
1510 #endif
1511 			if (number == 0)
1512 				st->flags &= ~ST_FIXEDBLOCKS;
1513 			else {
1514 				if ((st->blkmin || st->blkmax) &&
1515 				    (number < st->blkmin ||
1516 				    number > st->blkmax)) {
1517 					error = EINVAL;
1518 					break;
1519 				}
1520 				st->flags |= ST_FIXEDBLOCKS;
1521 			}
1522 			st->blksize = number;
1523 			st->flags |= ST_BLOCK_SET;	/*XXX */
1524 			goto try_new_value;
1525 		case MTSETDNSTY:	/* Set density for device and mode */
1526 			/*
1527 			 * Any number >= 0 and <= 0xff is legal. Numbers
1528 			 * above 0x80 are 'vendor unique'.
1529 			 */
1530 			if (number < 0 || number > 255) {
1531 				error = EINVAL;
1532 				break;
1533 			} else
1534 				st->density = number;
1535 			goto try_new_value;
1536 		case MTCMPRESS:
1537 			error = st->ops(st, (number == 0) ?
1538 			    ST_OPS_CMPRSS_OFF : ST_OPS_CMPRSS_ON,
1539 			    XS_CTL_SILENT);
1540 			break;
1541 		case MTEWARN:
1542 			if (number)
1543 				st->flags |= ST_EARLYWARN;
1544 			else
1545 				st->flags &= ~ST_EARLYWARN;
1546 			break;
1547 
1548 		default:
1549 			error = EINVAL;
1550 		}
1551 		break;
1552 	}
1553 	case MTIOCIEOT:
1554 	case MTIOCEEOT:
1555 		break;
1556 	case MTIOCRDSPOS:
1557 		error = st_rdpos(st, 0, (uint32_t *)arg);
1558 		break;
1559 	case MTIOCRDHPOS:
1560 		error = st_rdpos(st, 1, (uint32_t *)arg);
1561 		break;
1562 	case MTIOCSLOCATE:
1563 		error = st_setpos(st, 0, (uint32_t *)arg);
1564 		break;
1565 	case MTIOCHLOCATE:
1566 		error = st_setpos(st, 1, (uint32_t *)arg);
1567 		break;
1568 	default:
1569 		error = scsipi_do_ioctl(st->sc_periph, dev, cmd, arg, flag, l);
1570 		break;
1571 	}
1572 	return error;
1573 
1574 try_new_value:
1575 	/*
1576 	 * Check that the mode being asked for is aggreeable to the
1577 	 * drive. If not, put it back the way it was.
1578 	 *
1579 	 * If in control mode, we can make (persistent) mode changes
1580 	 * even if no medium is loaded (see st(4)).
1581 	 */
1582 	if ((STMODE(dev) != CTRL_MODE || (st->flags & ST_MOUNTED) != 0) &&
1583 	    (error = st->ops(st, ST_OPS_MODESELECT, 0)) != 0) {
1584 		/* put it back as it was */
1585 		aprint_error_dev(st->sc_dev, "cannot set selected mode\n");
1586 		st->density = hold_density;
1587 		st->blksize = hold_blksize;
1588 		if (st->blksize)
1589 			st->flags |= ST_FIXEDBLOCKS;
1590 		else
1591 			st->flags &= ~ST_FIXEDBLOCKS;
1592 		return error;
1593 	}
1594 	/*
1595 	 * As the drive liked it, if we are setting a new default,
1596 	 * set it into the structures as such.
1597 	 *
1598 	 * The means for deciding this are not finalised yet- but
1599 	 * if the device was opened in Control Mode, the values
1600 	 * are persistent now across mounts.
1601 	 */
1602 	if (STMODE(dev) == CTRL_MODE) {
1603 		switch ((short) (mt->mt_op)) {
1604 		case MTSETBSIZ:
1605 			st->modes[dsty].blksize = st->blksize;
1606 			st->modeflags[dsty] |= BLKSIZE_SET_BY_USER;
1607 			break;
1608 		case MTSETDNSTY:
1609 			st->modes[dsty].density = st->density;
1610 			st->modeflags[dsty] |= DENSITY_SET_BY_USER;
1611 			break;
1612 		}
1613 	}
1614 	return 0;
1615 }
1616 
1617 /* Do a synchronous read. */
1618 static int
1619 st_read(struct st_softc *st, char *bf, int size, int flags)
1620 {
1621 	struct scsi_rw_tape cmd;
1622 
1623 	/* If it's a null transfer, return immediatly */
1624 	if (size == 0)
1625 		return 0;
1626 	memset(&cmd, 0, sizeof(cmd));
1627 	cmd.opcode = READ;
1628 	if (st->flags & ST_FIXEDBLOCKS) {
1629 		cmd.byte2 |= SRW_FIXED;
1630 		_lto3b(size / (st->blksize ? st->blksize : DEF_FIXED_BSIZE),
1631 		    cmd.len);
1632 	} else
1633 		_lto3b(size, cmd.len);
1634 	return scsipi_command(st->sc_periph,
1635 	    (void *)&cmd, sizeof(cmd), (void *)bf, size, 0, ST_IO_TIME, NULL,
1636 	    flags | XS_CTL_DATA_IN);
1637 }
1638 
1639 /* issue an erase command */
1640 static int
1641 st_erase(struct st_softc *st, int full, int flags)
1642 {
1643 	int tmo;
1644 	struct scsi_erase cmd;
1645 
1646 	/*
1647 	 * Full erase means set LONG bit in erase command, which asks
1648 	 * the drive to erase the entire unit.  Without this bit, we're
1649 	 * asking the drive to write an erase gap.
1650 	 */
1651 	memset(&cmd, 0, sizeof(cmd));
1652 	cmd.opcode = ERASE;
1653 	if (full) {
1654 		cmd.byte2 = SE_LONG;
1655 		tmo = ST_SPC_TIME;
1656 	} else
1657 		tmo = ST_IO_TIME;
1658 
1659 	/*
1660 	 * XXX We always do this asynchronously, for now, unless the device
1661 	 * has the ST_Q_ERASE_NOIMM quirk.  How long should we wait if we
1662 	 * want to (eventually) to it synchronously?
1663 	 */
1664 	if ((st->quirks & ST_Q_ERASE_NOIMM) == 0)
1665 		cmd.byte2 |= SE_IMMED;
1666 
1667 	return scsipi_command(st->sc_periph, (void *)&cmd, sizeof(cmd), 0, 0,
1668 	    ST_RETRIES, tmo, NULL, flags);
1669 }
1670 
1671 /* skip N blocks/filemarks/seq filemarks/eom */
1672 static int
1673 st_space(struct st_softc *st, int number, u_int what, int flags)
1674 {
1675 	struct scsi_space cmd;
1676 	int error;
1677 
1678 	switch (what) {
1679 	case SP_BLKS:
1680 		if (st->flags & ST_PER_ACTION) {
1681 			if (number > 0) {
1682 				st->flags &= ~ST_PER_ACTION;
1683 				return EIO;
1684 			} else if (number < 0) {
1685 				if (st->flags & ST_AT_FILEMARK) {
1686 					/*
1687 					 * Handling of ST_AT_FILEMARK
1688 					 * in st_space will fill in the
1689 					 * right file mark count.
1690 					 */
1691 					error = st_space(st, 0, SP_FILEMARKS,
1692 					    flags);
1693 					if (error)
1694 						return error;
1695 				}
1696 				if (st->flags & ST_BLANK_READ) {
1697 					st->flags &= ~ST_BLANK_READ;
1698 					return EIO;
1699 				}
1700 				st->flags &= ~(ST_EIO_PENDING|ST_EOM_PENDING);
1701 			}
1702 		}
1703 		break;
1704 	case SP_FILEMARKS:
1705 		if (st->flags & ST_EIO_PENDING) {
1706 			if (number > 0) {
1707 				/* pretend we just discovered the error */
1708 				st->flags &= ~ST_EIO_PENDING;
1709 				return EIO;
1710 			} else if (number < 0) {
1711 				/* back away from the error */
1712 				st->flags &= ~ST_EIO_PENDING;
1713 			}
1714 		}
1715 		if (st->flags & ST_AT_FILEMARK) {
1716 			st->flags &= ~ST_AT_FILEMARK;
1717 			number--;
1718 		}
1719 		if ((st->flags & ST_BLANK_READ) && (number < 0)) {
1720 			/* back away from unwritten tape */
1721 			st->flags &= ~ST_BLANK_READ;
1722 			number++;	/* XXX dubious */
1723 		}
1724 		break;
1725 	case SP_EOM:
1726 		if (st->flags & ST_EOM_PENDING) {
1727 			/* we're already there */
1728 			st->flags &= ~ST_EOM_PENDING;
1729 			return 0;
1730 		}
1731 		if (st->flags & ST_EIO_PENDING) {
1732 			/* pretend we just discovered the error */
1733 			st->flags &= ~ST_EIO_PENDING;
1734 			return EIO;
1735 		}
1736 		if (st->flags & ST_AT_FILEMARK)
1737 			st->flags &= ~ST_AT_FILEMARK;
1738 		break;
1739 	}
1740 	if (number == 0)
1741 		return 0;
1742 
1743 	memset(&cmd, 0, sizeof(cmd));
1744 	cmd.opcode = SPACE;
1745 	cmd.byte2 = what;
1746 	_lto3b(number, cmd.number);
1747 
1748 	st->flags &= ~ST_POSUPDATED;
1749 	st->last_ctl_resid = 0;
1750 	error = scsipi_command(st->sc_periph, (void *)&cmd, sizeof(cmd), 0, 0,
1751 	    0, ST_SPC_TIME, NULL, flags);
1752 
1753 	if (error == 0 && (st->flags & ST_POSUPDATED) == 0) {
1754 		number = number - st->last_ctl_resid;
1755 		if (what == SP_BLKS) {
1756 			if (st->blkno != -1)
1757 				st->blkno += number;
1758 		} else if (what == SP_FILEMARKS) {
1759 			if (st->fileno != -1) {
1760 				st->fileno += number;
1761 				if (number > 0)
1762 					st->blkno = 0;
1763 				else if (number < 0)
1764 					st->blkno = -1;
1765 			}
1766 		} else if (what == SP_EOM) {
1767 			/* This loses us relative position. */
1768 			st->fileno = st->blkno = -1;
1769 		}
1770 	}
1771 	return error;
1772 }
1773 
1774 /*
1775  * write N filemarks
1776  */
1777 static int
1778 st_write_filemarks(struct st_softc *st, int number, int flags)
1779 {
1780 	int error;
1781 	struct scsi_write_filemarks cmd;
1782 
1783 	/*
1784 	 * It's hard to write a negative number of file marks.
1785 	 * Don't try.
1786 	 */
1787 	if (number < 0)
1788 		return EINVAL;
1789 	switch (number) {
1790 	case 0:		/* really a command to sync the drive's buffers */
1791 		break;
1792 	case 1:
1793 		if (st->flags & ST_FM_WRITTEN)	/* already have one down */
1794 			st->flags &= ~ST_WRITTEN;
1795 		else
1796 			st->flags |= ST_FM_WRITTEN;
1797 		st->flags &= ~ST_PER_ACTION;
1798 		break;
1799 	default:
1800 		st->flags &= ~(ST_PER_ACTION | ST_WRITTEN);
1801 	}
1802 
1803 	memset(&cmd, 0, sizeof(cmd));
1804 	cmd.opcode = WRITE_FILEMARKS;
1805 	if (SCSIPI_BUSTYPE_TYPE(scsipi_periph_bustype(st->sc_periph)) ==
1806 	    SCSIPI_BUSTYPE_ATAPI)
1807 		cmd.byte2 = SR_IMMED;
1808 	/*
1809 	 * The ATAPI Onstream DI-30 doesn't support writing filemarks, but
1810 	 * WRITE_FILEMARKS is still used to flush the buffer
1811 	 */
1812 	if ((st->quirks & ST_Q_NOFILEMARKS) == 0)
1813 		_lto3b(number, cmd.number);
1814 
1815 	/* XXX WE NEED TO BE ABLE TO GET A RESIDIUAL XXX */
1816 	error = scsipi_command(st->sc_periph, (void *)&cmd, sizeof(cmd), 0, 0,
1817 	    0, ST_IO_TIME * 4, NULL, flags);
1818 	if (error == 0 && st->fileno != -1)
1819 		st->fileno += number;
1820 	return error;
1821 }
1822 
1823 /*
1824  * Make sure the right number of file marks is on tape if the
1825  * tape has been written.  If the position argument is true,
1826  * leave the tape positioned where it was originally.
1827  *
1828  * nmarks returns the number of marks to skip (or, if position
1829  * true, which were skipped) to get back original position.
1830  */
1831 static int
1832 st_check_eod(struct st_softc *st, boolean position, int *nmarks, int flags)
1833 {
1834 	int error;
1835 
1836 	switch (st->flags & (ST_WRITTEN | ST_FM_WRITTEN | ST_2FM_AT_EOD)) {
1837 	default:
1838 		*nmarks = 0;
1839 		return 0;
1840 	case ST_WRITTEN:
1841 	case ST_WRITTEN | ST_FM_WRITTEN | ST_2FM_AT_EOD:
1842 		*nmarks = 1;
1843 		break;
1844 	case ST_WRITTEN | ST_2FM_AT_EOD:
1845 		*nmarks = 2;
1846 	}
1847 	error = st_write_filemarks(st, *nmarks, flags);
1848 	if (position && !error)
1849 		error = st_space(st, -*nmarks, SP_FILEMARKS, flags);
1850 	return error;
1851 }
1852 
1853 /* load/unload/retension */
1854 static int
1855 st_load(struct st_softc *st, u_int type, int flags)
1856 {
1857 	int error;
1858 	struct scsi_load cmd;
1859 
1860 	if (type != LD_LOAD) {
1861 		int nmarks;
1862 
1863 		error = st_check_eod(st, FALSE, &nmarks, flags);
1864 		if (error) {
1865 			aprint_error_dev(st->sc_dev,
1866 			    "failed to write closing filemarks at "
1867 			    "unload, errno=%d\n", error);
1868 			return error;
1869 		}
1870 	}
1871 	if (st->quirks & ST_Q_IGNORE_LOADS) {
1872 		if (type == LD_LOAD)
1873 			/*
1874 			 * If we ignore loads, at least we should try a rewind.
1875 			 */
1876 			return st_rewind(st, 0, flags);
1877 		/* otherwise, we should do what's asked of us */
1878 	}
1879 
1880 	memset(&cmd, 0, sizeof(cmd));
1881 	cmd.opcode = LOAD;
1882 	if (SCSIPI_BUSTYPE_TYPE(scsipi_periph_bustype(st->sc_periph)) ==
1883 	    SCSIPI_BUSTYPE_ATAPI)
1884 		cmd.byte2 = SR_IMMED;
1885 	cmd.how = type;
1886 
1887 	error = scsipi_command(st->sc_periph, (void *)&cmd, sizeof(cmd), 0, 0,
1888 	    ST_RETRIES, ST_SPC_TIME, NULL, flags);
1889 	if (error) {
1890 		aprint_error_dev(st->sc_dev, "error %d in st_load (op %d)\n",
1891 		    error, type);
1892 	}
1893 	return error;
1894 }
1895 
1896 /* Rewind the device */
1897 static int
1898 st_rewind(struct st_softc *st, u_int immediate, int flags)
1899 {
1900 	struct scsi_rewind cmd;
1901 	int error;
1902 	int nmarks;
1903 	int timeout;
1904 
1905 	error = st_check_eod(st, FALSE, &nmarks, flags);
1906 	if (error) {
1907 		aprint_error_dev(st->sc_dev,
1908 		    "failed to write closing filemarks at "
1909 		    "rewind, errno=%d\n", error);
1910 		return error;
1911 	}
1912 	st->flags &= ~ST_PER_ACTION;
1913 
1914 	/* If requestor asked for immediate response, set a short timeout */
1915 	timeout = immediate ? ST_CTL_TIME : ST_SPC_TIME;
1916 
1917 	/* ATAPI tapes always need immediate to be set */
1918 	if (scsipi_periph_bustype(st->sc_periph) == SCSIPI_BUSTYPE_ATAPI)
1919 		immediate = SR_IMMED;
1920 
1921 	memset(&cmd, 0, sizeof(cmd));
1922 	cmd.opcode = REWIND;
1923 	cmd.byte2 = immediate;
1924 
1925 	error = scsipi_command(st->sc_periph, (void *)&cmd, sizeof(cmd), 0, 0,
1926 	    ST_RETRIES, timeout, NULL, flags);
1927 	if (error) {
1928 		aprint_error_dev(st->sc_dev, "error %d trying to rewind\n",
1929 		    error);
1930 		/* lost position */
1931 		st->fileno = st->blkno = -1;
1932 	} else
1933 		st->fileno = st->blkno = 0;
1934 	return error;
1935 }
1936 
1937 static int
1938 st_rdpos(struct st_softc *st, int hard, uint32_t *blkptr)
1939 {
1940 	int error;
1941 	uint8_t posdata[20];
1942 	struct scsi_tape_read_position cmd;
1943 
1944 	/*
1945 	 * We try and flush any buffered writes here if we were writing
1946 	 * and we're trying to get hardware block position. It eats
1947 	 * up performance substantially, but I'm wary of drive firmware.
1948 	 *
1949 	 * I think that *logical* block position is probably okay-
1950 	 * but hardware block position might have to wait for data
1951 	 * to hit media to be valid. Caveat Emptor.
1952 	 */
1953 
1954 	if (hard && (st->flags & ST_WRITTEN)) {
1955 		/* First flush any pending writes... */
1956 		error = st_write_filemarks(st, 0, XS_CTL_SILENT);
1957 		/*
1958 		 * The latter case is for 'write protected' tapes
1959 		 * which are too stupid to recognize a zero count
1960 		 * for writing filemarks as a no-op.
1961 		 */
1962 		if (error != 0 && error != EACCES && error != EROFS)
1963 			return error;
1964 	}
1965 
1966 	memset(&cmd, 0, sizeof(cmd));
1967 	memset(&posdata, 0, sizeof(posdata));
1968 	cmd.opcode = READ_POSITION;
1969 	if (hard)
1970 		cmd.byte1 = 1;
1971 
1972 	error = scsipi_command(st->sc_periph, (void *)&cmd, sizeof(cmd),
1973 	    (void *)&posdata, sizeof(posdata), ST_RETRIES, ST_CTL_TIME, NULL,
1974 	    XS_CTL_SILENT | XS_CTL_DATA_IN);
1975 
1976 	if (error == 0) {
1977 #if	0
1978 		printf("posdata:");
1979 		for (hard = 0; hard < sizeof(posdata); hard++)
1980 			printf("%02x ", posdata[hard] & 0xff);
1981 		printf("\n");
1982 #endif
1983 		if (posdata[0] & 0x4)	/* Block Position Unknown */
1984 			error = EINVAL;
1985 		else
1986 			*blkptr = _4btol(&posdata[4]);
1987 	}
1988 	return error;
1989 }
1990 
1991 static int
1992 st_setpos(struct st_softc *st, int hard, uint32_t *blkptr)
1993 {
1994 	int error;
1995 	struct scsi_tape_locate cmd;
1996 
1997 	/*
1998 	 * We used to try and flush any buffered writes here.
1999 	 * Now we push this onto user applications to either
2000 	 * flush the pending writes themselves (via a zero count
2001 	 * WRITE FILEMARKS command) or they can trust their tape
2002 	 * drive to do this correctly for them.
2003 	 *
2004 	 * There are very ugly performance limitations otherwise.
2005 	 */
2006 
2007 	memset(&cmd, 0, sizeof(cmd));
2008 	cmd.opcode = LOCATE;
2009 	if (hard)
2010 		cmd.byte2 = 1 << 2;
2011 	_lto4b(*blkptr, cmd.blkaddr);
2012 	error = scsipi_command(st->sc_periph, (void *)&cmd, sizeof(cmd), 0, 0,
2013 	    ST_RETRIES, ST_SPC_TIME, NULL, 0);
2014 	/*
2015 	 * Note file && block number position now unknown (if
2016 	 * these things ever start being maintained in this driver)
2017 	 */
2018 	st->fileno = st->blkno = -1;
2019 	return error;
2020 }
2021 
2022 
2023 /*
2024  * Look at the returned sense and act on the error and determine
2025  * the unix error number to pass back..., 0 (== report no error),
2026  * -1 = retry the operation, -2 continue error processing.
2027  */
2028 static int
2029 st_interpret_sense(struct scsipi_xfer *xs)
2030 {
2031 	struct scsipi_periph *periph = xs->xs_periph;
2032 	struct scsi_sense_data *sense = &xs->sense.scsi_sense;
2033 	struct buf *bp = xs->bp;
2034 	struct st_softc *st = device_private(periph->periph_dev);
2035 	int retval = EJUSTRETURN;
2036 	int doprint = ((xs->xs_control & XS_CTL_SILENT) == 0);
2037 	uint8_t key;
2038 	int32_t info;
2039 
2040 	/*
2041 	 * If it isn't a extended or extended/deferred error, let
2042 	 * the generic code handle it.
2043 	 */
2044 	if (SSD_RCODE(sense->response_code) != SSD_RCODE_CURRENT &&
2045 	    SSD_RCODE(sense->response_code) != SSD_RCODE_DEFERRED)
2046 		return retval;
2047 
2048 	if (sense->response_code & SSD_RCODE_VALID)
2049 		info = _4btol(sense->info);
2050 	else
2051 		info = (st->flags & ST_FIXEDBLOCKS) ?
2052 		    xs->datalen / st->blksize : xs->datalen;
2053 	key = SSD_SENSE_KEY(sense->flags);
2054 	st->mt_erreg = key;
2055 	st->asc = sense->asc;
2056 	st->ascq = sense->ascq;
2057 	st->mt_resid = (short) info;
2058 
2059 	if (key == SKEY_NOT_READY && st->asc == 0x4 && st->ascq == 0x1) {
2060 		/* Not Ready, Logical Unit Is in Process Of Becoming Ready */
2061 		if (!callout_pending(&periph->periph_callout))
2062 			scsipi_periph_freeze(periph, 1);
2063 		callout_reset(&periph->periph_callout,
2064 		    hz, scsipi_periph_timed_thaw, periph);
2065 		return ERESTART;
2066 	}
2067 
2068 	/* If the device is not open yet, let generic handle */
2069 	if ((periph->periph_flags & PERIPH_OPEN) == 0)
2070 		return retval;
2071 
2072 	xs->resid = info;
2073 	if (st->flags & ST_FIXEDBLOCKS) {
2074 		if (bp) {
2075 			xs->resid *= st->blksize;
2076 			st->last_io_resid = xs->resid;
2077 		} else
2078 			st->last_ctl_resid = xs->resid;
2079 		if (key == SKEY_VOLUME_OVERFLOW) {
2080 			st->flags |= ST_EIO_PENDING;
2081 			if (bp)
2082 				bp->b_resid = xs->resid;
2083 		} else if (sense->flags & SSD_EOM) {
2084 			if ((st->flags & ST_EARLYWARN) == 0)
2085 				st->flags |= ST_EIO_PENDING;
2086 			st->flags |= ST_EOM_PENDING;
2087 			if (bp) {
2088 #if 0
2089 				bp->b_resid = xs->resid;
2090 #else
2091 				/*
2092 				 * Grotesque as it seems, the few times
2093 				 * I've actually seen a non-zero resid,
2094 				 * the tape drive actually lied and had
2095 				 * written all the data!
2096 				 */
2097 				bp->b_resid = 0;
2098 #endif
2099 			}
2100 		}
2101 		if (sense->flags & SSD_FILEMARK) {
2102 			st->flags |= ST_AT_FILEMARK;
2103 			if (bp)
2104 				bp->b_resid = xs->resid;
2105 			if (st->fileno != (daddr_t) -1) {
2106 				st->fileno++;
2107 				st->blkno = 0;
2108 				st->flags |= ST_POSUPDATED;
2109 			}
2110 		}
2111 		if (sense->flags & SSD_ILI) {
2112 			st->flags |= ST_EIO_PENDING;
2113 			if (bp)
2114 				bp->b_resid = xs->resid;
2115 			if (sense->response_code & SSD_RCODE_VALID &&
2116 			    (xs->xs_control & XS_CTL_SILENT) == 0)
2117 				aprint_error_dev(st->sc_dev,
2118 				    "block wrong size, %d blocks residual\n",
2119 				    info);
2120 
2121 			/*
2122 			 * This quirk code helps the drive read
2123 			 * the first tape block, regardless of
2124 			 * format.  That is required for these
2125 			 * drives to return proper MODE SENSE
2126 			 * information.
2127 			 */
2128 			if ((st->quirks & ST_Q_SENSE_HELP) &&
2129 			    (periph->periph_flags & PERIPH_MEDIA_LOADED) == 0)
2130 				st->blksize -= 512;
2131 			else if ((st->flags & ST_POSUPDATED) == 0) {
2132 				if (st->blkno != (daddr_t) -1) {
2133 					st->blkno +=
2134 					    (xs->datalen / st->blksize);
2135 					st->flags |= ST_POSUPDATED;
2136 				}
2137 			}
2138 		}
2139 		/*
2140 		 * If data wanted and no data was transferred, do it immediately
2141 		 */
2142 		if (xs->datalen && xs->resid >= xs->datalen) {
2143 			if (st->flags & ST_EIO_PENDING)
2144 				return EIO;
2145 			if (st->flags & ST_AT_FILEMARK) {
2146 				if (bp)
2147 					bp->b_resid = xs->resid;
2148 				return 0;
2149 			}
2150 		}
2151 	} else {		/* must be variable mode */
2152 		if (bp)
2153 			st->last_io_resid = xs->resid;
2154 		else
2155 			st->last_ctl_resid = xs->resid;
2156 		if (sense->flags & SSD_EOM) {
2157 			/*
2158 			 * The current semantics of this
2159 			 * driver requires EOM detection
2160 			 * to return EIO unless early
2161 			 * warning detection is enabled
2162 			 * for variable mode (this is always
2163 			 * on for fixed block mode).
2164 			 */
2165 			if (st->flags & ST_EARLYWARN) {
2166 				st->flags |= ST_EOM_PENDING;
2167 				retval = 0;
2168 			} else {
2169 				retval = EIO;
2170 				/*
2171 				 * If we return an error we can't claim to
2172 				 * have transfered all data.
2173 				 */
2174 				if (xs->resid == 0)
2175 					xs->resid = xs->datalen;
2176 			}
2177 
2178 			/*
2179 			 * If it's an unadorned EOM detection,
2180 			 * suppress printing an error.
2181 			 */
2182 			if (key == SKEY_NO_SENSE) {
2183 				doprint = 0;
2184 			}
2185 		} else if (sense->flags & SSD_FILEMARK) {
2186 			retval = 0;
2187 			if (st->fileno != (daddr_t) -1) {
2188 				st->fileno++;
2189 				st->blkno = 0;
2190 				st->flags |= ST_POSUPDATED;
2191 			}
2192 		} else if (sense->flags & SSD_ILI) {
2193 			if (info < 0) {
2194 				/*
2195 				 * The tape record was bigger than the read
2196 				 * we issued.
2197 				 */
2198 				if ((xs->xs_control & XS_CTL_SILENT) == 0) {
2199 					aprint_error_dev(st->sc_dev,
2200 					    "%d-byte tape record too big"
2201 					    " for %d-byte user buffer\n",
2202 					    xs->datalen - info, xs->datalen);
2203 				}
2204 				retval = EIO;
2205 			} else {
2206 				retval = 0;
2207 				if (st->blkno != (daddr_t) -1) {
2208 					st->blkno++;
2209 					st->flags |= ST_POSUPDATED;
2210 				}
2211 			}
2212 		}
2213 		if (bp)
2214 			bp->b_resid = xs->resid;
2215 	}
2216 
2217 #ifndef SCSIPI_DEBUG
2218 	if (retval == 0 && key == SKEY_NO_SENSE)
2219 		doprint = 0;
2220 #endif
2221 	if (key == SKEY_BLANK_CHECK) {
2222 		/*
2223 		 * This quirk code helps the drive read the
2224 		 * first tape block, regardless of format.  That
2225 		 * is required for these drives to return proper
2226 		 * MODE SENSE information.
2227 		 */
2228 		if ((st->quirks & ST_Q_SENSE_HELP) &&
2229 		    (periph->periph_flags & PERIPH_MEDIA_LOADED) == 0) {
2230 			/* still starting */
2231 			st->blksize -= 512;
2232 		} else if (!(st->flags & (ST_2FM_AT_EOD | ST_BLANK_READ))) {
2233 			st->flags |= ST_BLANK_READ;
2234 			xs->resid = xs->datalen;
2235 			if (bp) {
2236 				bp->b_resid = xs->resid;
2237 				/* return an EOF */
2238 			}
2239 			retval = 0;
2240 			/* lost position */
2241 			st->fileno = st->blkno = -1;
2242 		}
2243 	}
2244 
2245 	/*
2246 	 * If generic sense processing will continue, we should not
2247 	 * print sense info here.
2248 	 */
2249 	if (retval == EJUSTRETURN)
2250 		doprint = 0;
2251 
2252 	if (doprint) {
2253 		/* Print verbose sense info if possible */
2254 		if (scsipi_print_sense(xs, 0) != 0)
2255 			return retval;
2256 
2257 		/* Print less-verbose sense info */
2258 		scsipi_printaddr(periph);
2259 		printf("Sense Key 0x%02x", key);
2260 		if ((sense->response_code & SSD_RCODE_VALID) != 0) {
2261 			switch (key) {
2262 			case SKEY_NOT_READY:
2263 			case SKEY_ILLEGAL_REQUEST:
2264 			case SKEY_UNIT_ATTENTION:
2265 			case SKEY_DATA_PROTECT:
2266 				break;
2267 			case SKEY_VOLUME_OVERFLOW:
2268 			case SKEY_BLANK_CHECK:
2269 				printf(", requested size: %d (decimal)", info);
2270 				break;
2271 			case SKEY_ABORTED_COMMAND:
2272 				if (xs->xs_retries)
2273 					printf(", retrying");
2274 				printf(", cmd 0x%x, info 0x%x",
2275 				    xs->cmd->opcode, info);
2276 				break;
2277 			default:
2278 				printf(", info = %d (decimal)", info);
2279 			}
2280 		}
2281 		if (sense->extra_len != 0) {
2282 			int n;
2283 			printf(", data =");
2284 			for (n = 0; n < sense->extra_len; n++)
2285 				printf(" %02x", sense->csi[n]);
2286 		}
2287 		printf("\n");
2288 	}
2289 	return retval;
2290 }
2291 
2292 /*
2293  * The quirk here is that the drive returns some value to st_mode_sense
2294  * incorrectly until the tape has actually passed by the head.
2295  *
2296  * The method is to set the drive to large fixed-block state (user-specified
2297  * density and 1024-byte blocks), then read and rewind to get it to sense the
2298  * tape.  If that doesn't work, try 512-byte fixed blocks.  If that doesn't
2299  * work, as a last resort, try variable- length blocks.  The result will be
2300  * the ability to do an accurate st_mode_sense.
2301  *
2302  * We know we can do a rewind because we just did a load, which implies rewind.
2303  * Rewind seems preferable to space backward if we have a virgin tape.
2304  *
2305  * The rest of the code for this quirk is in ILI processing and BLANK CHECK
2306  * error processing, both part of st_interpret_sense.
2307  */
2308 static int
2309 st_touch_tape(struct st_softc *st)
2310 {
2311 	char *bf;
2312 	int readsize;
2313 	int error;
2314 
2315 	bf = malloc(1024, M_TEMP, M_NOWAIT);
2316 	if (bf == NULL)
2317 		return ENOMEM;
2318 
2319 	if ((error = st->ops(st, ST_OPS_MODESENSE, 0)) != 0)
2320 		goto bad;
2321 
2322 	/*
2323 	 * If the block size is already known from the
2324 	 * sense data, use it. Else start probing at 1024.
2325 	 */
2326 	if (st->media_blksize > 0)
2327 		st->blksize = st->media_blksize;
2328 	else
2329 		st->blksize = 1024;
2330 
2331 	do {
2332 		switch (st->blksize) {
2333 		case 512:
2334 		case 1024:
2335 			readsize = st->blksize;
2336 			st->flags |= ST_FIXEDBLOCKS;
2337 			break;
2338 		default:
2339 			readsize = 1;
2340 			st->flags &= ~ST_FIXEDBLOCKS;
2341 		}
2342 		if ((error = st->ops(st, ST_OPS_MODESELECT, XS_CTL_SILENT))
2343 		    != 0) {
2344 			/*
2345 			 * The device did not agree with the proposed
2346 			 * block size. If we exhausted our options,
2347 			 * return failure, else try another.
2348 			 */
2349 			if (readsize == 1)
2350 				goto bad;
2351 			st->blksize -= 512;
2352 			continue;
2353 		}
2354 		st_read(st, bf, readsize, XS_CTL_SILENT);	/* XXX */
2355 		if ((error = st_rewind(st, 0, 0)) != 0) {
2356 bad:			free(bf, M_TEMP);
2357 			return error;
2358 		}
2359 	} while (readsize != 1 && readsize > st->blksize);
2360 
2361 	free(bf, M_TEMP);
2362 	return 0;
2363 }
2364 
2365 static int
2366 stdump(dev_t dev, daddr_t blkno, void *va, size_t size)
2367 {
2368 	/* Not implemented. */
2369 	return ENXIO;
2370 }
2371 
2372 /*
2373  * Send a filled out parameter structure to the drive to
2374  * set it into the desire modes etc.
2375  */
2376 int
2377 st_mode_select(struct st_softc *st, int flags)
2378 {
2379 	u_int select_len;
2380 	struct select {
2381 		struct scsi_mode_parameter_header_6 header;
2382 		struct scsi_general_block_descriptor blk_desc;
2383 		u_char sense_data[MAX_PAGE_0_SIZE];
2384 	} select;
2385 	struct scsipi_periph *periph = st->sc_periph;
2386 
2387 	select_len = sizeof(select.header) + sizeof(select.blk_desc) +
2388 		     st->page_0_size;
2389 
2390 	/*
2391 	 * This quirk deals with drives that have only one valid mode
2392 	 * and think this gives them license to reject all mode selects,
2393 	 * even if the selected mode is the one that is supported.
2394 	 */
2395 	if (st->quirks & ST_Q_UNIMODAL) {
2396 		SC_DEBUG(periph, SCSIPI_DB3,
2397 		    ("not setting density 0x%x blksize 0x%x\n",
2398 		    st->density, st->blksize));
2399 		return 0;
2400 	}
2401 
2402 	/* Set up for a mode select */
2403 	memset(&select, 0, sizeof(select));
2404 	select.header.blk_desc_len = sizeof(struct
2405 	    scsi_general_block_descriptor);
2406 	select.header.dev_spec &= ~SMH_DSP_BUFF_MODE;
2407 	select.blk_desc.density = st->density;
2408 	if (st->flags & ST_DONTBUFFER)
2409 		select.header.dev_spec |= SMH_DSP_BUFF_MODE_OFF;
2410 	else
2411 		select.header.dev_spec |= SMH_DSP_BUFF_MODE_ON;
2412 	if (st->flags & ST_FIXEDBLOCKS)
2413 		_lto3b(st->blksize, select.blk_desc.blklen);
2414 	if (st->page_0_size)
2415 		memcpy(select.sense_data, st->sense_data, st->page_0_size);
2416 
2417 	/* do the command */
2418 	return scsipi_mode_select(periph, 0, &select.header, select_len,
2419 				  flags, ST_RETRIES, ST_CTL_TIME);
2420 }
2421