xref: /netbsd-src/sys/dev/scsipi/st.c (revision d9ac053afa92f3d7a493f791e10558f738234217)
1 /*	$NetBSD: st.c,v 1.191 2006/06/07 22:33:37 kardel 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  * 3. All advertising materials mentioning features or use of this software
19  *    must display the following acknowledgement:
20  *        This product includes software developed by the NetBSD
21  *        Foundation, Inc. and its contributors.
22  * 4. Neither the name of The NetBSD Foundation nor the names of its
23  *    contributors may be used to endorse or promote products derived
24  *    from this software without specific prior written permission.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36  * POSSIBILITY OF SUCH DAMAGE.
37  */
38 
39 /*
40  * Originally written by Julian Elischer (julian@tfs.com)
41  * for TRW Financial Systems for use under the MACH(2.5) operating system.
42  *
43  * TRW Financial Systems, in accordance with their agreement with Carnegie
44  * Mellon University, makes this software available to CMU to distribute
45  * or use in any manner that they see fit as long as this message is kept with
46  * the software. For this reason TFS also grants any other persons or
47  * organisations permission to use or modify this software.
48  *
49  * TFS supplies this software to be publicly redistributed
50  * on the understanding that TFS is not responsible for the correct
51  * functioning of this software in any circumstances.
52  *
53  * Ported to run under 386BSD by Julian Elischer (julian@tfs.com) Sept 1992
54  * major changes by Julian Elischer (julian@jules.dialix.oz.au) May 1993
55  *
56  * A lot of rewhacking done by mjacob (mjacob@nas.nasa.gov).
57  */
58 
59 #include <sys/cdefs.h>
60 __KERNEL_RCSID(0, "$NetBSD: st.c,v 1.191 2006/06/07 22:33:37 kardel Exp $");
61 
62 #include "opt_scsi.h"
63 
64 #include <sys/param.h>
65 #include <sys/systm.h>
66 #include <sys/fcntl.h>
67 #include <sys/errno.h>
68 #include <sys/ioctl.h>
69 #include <sys/malloc.h>
70 #include <sys/buf.h>
71 #include <sys/bufq.h>
72 #include <sys/proc.h>
73 #include <sys/user.h>
74 #include <sys/mtio.h>
75 #include <sys/device.h>
76 #include <sys/conf.h>
77 #include <sys/kernel.h>
78 #include <sys/vnode.h>
79 #include <sys/iostat.h>
80 #include <sys/sysctl.h>
81 
82 #include <dev/scsipi/scsi_spc.h>
83 #include <dev/scsipi/scsipi_all.h>
84 #include <dev/scsipi/scsi_all.h>
85 #include <dev/scsipi/scsi_tape.h>
86 #include <dev/scsipi/scsipiconf.h>
87 #include <dev/scsipi/scsipi_base.h>
88 #include <dev/scsipi/stvar.h>
89 
90 /* Defines for device specific stuff */
91 #define DEF_FIXED_BSIZE  512
92 
93 #define STMODE(z)	( minor(z)       & 0x03)
94 #define STDSTY(z)	((minor(z) >> 2) & 0x03)
95 #define STUNIT(z)	((minor(z) >> 4)       )
96 #define STNMINOR	16
97 
98 #define NORMAL_MODE	0
99 #define NOREW_MODE	1
100 #define EJECT_MODE	2
101 #define CTRL_MODE	3
102 
103 #define	FALSE		0
104 #define	TRUE		1
105 
106 #ifndef		ST_MOUNT_DELAY
107 #define		ST_MOUNT_DELAY		0
108 #endif
109 
110 static dev_type_open(stopen);
111 static dev_type_close(stclose);
112 static dev_type_read(stread);
113 static dev_type_write(stwrite);
114 static dev_type_ioctl(stioctl);
115 static dev_type_strategy(ststrategy);
116 static dev_type_dump(stdump);
117 
118 const struct bdevsw st_bdevsw = {
119 	stopen, stclose, ststrategy, stioctl, stdump, nosize, D_TAPE
120 };
121 
122 const struct cdevsw st_cdevsw = {
123 	stopen, stclose, stread, stwrite, stioctl,
124 	nostop, notty, nopoll, nommap, nokqfilter, D_TAPE
125 };
126 
127 /*
128  * Define various devices that we know mis-behave in some way,
129  * and note how they are bad, so we can correct for them
130  */
131 
132 static const struct st_quirk_inquiry_pattern st_quirk_patterns[] = {
133 	{{T_SEQUENTIAL, T_REMOV,
134 	 "        ", "                ", "    "}, {0, 0, {
135 		{ST_Q_FORCE_BLKSIZE, 512, 0},		/* minor 0-3 */
136 		{ST_Q_FORCE_BLKSIZE, 512, QIC_24},	/* minor 4-7 */
137 		{ST_Q_FORCE_BLKSIZE, 0, HALFINCH_1600},	/* minor 8-11 */
138 		{ST_Q_FORCE_BLKSIZE, 0, HALFINCH_6250}	/* minor 12-15 */
139 	}}},
140 	{{T_SEQUENTIAL, T_REMOV,
141 	 "TANDBERG", " TDC 3600       ", ""},     {0, 12, {
142 		{0, 0, 0},				/* minor 0-3 */
143 		{ST_Q_FORCE_BLKSIZE, 0, QIC_525},	/* minor 4-7 */
144 		{0, 0, QIC_150},			/* minor 8-11 */
145 		{0, 0, QIC_120}				/* minor 12-15 */
146 	}}},
147  	{{T_SEQUENTIAL, T_REMOV,
148  	 "TANDBERG", " TDC 3800       ", ""},     {0, 0, {
149 		{ST_Q_FORCE_BLKSIZE, 512, 0},		/* minor 0-3 */
150 		{0, 0, QIC_525},			/* minor 4-7 */
151 		{0, 0, QIC_150},			/* minor 8-11 */
152 		{0, 0, QIC_120}				/* minor 12-15 */
153 	}}},
154 	{{T_SEQUENTIAL, T_REMOV,
155 	  "TANDBERG", " SLR5 4/8GB     ", ""},     {0, 0, {
156 		{ST_Q_FORCE_BLKSIZE, 1024, 0},		/* minor 0-3 */
157 		{0, 0, 0},				/* minor 4-7 */
158 		{0, 0, 0},				/* minor 8-11 */
159 		{0, 0, 0}				/* minor 12-15 */
160 	}}},
161 	/*
162 	 * lacking a manual for the 4200, it's not clear what the
163 	 * specific density codes should be- the device is a 2.5GB
164 	 * capable QIC drive, those density codes aren't readily
165 	 * availabel. The 'default' will just have to do.
166 	 */
167  	{{T_SEQUENTIAL, T_REMOV,
168  	 "TANDBERG", " TDC 4200       ", ""},     {0, 0, {
169 		{ST_Q_FORCE_BLKSIZE, 512, 0},		/* minor 0-3 */
170 		{0, 0, QIC_525},			/* minor 4-7 */
171 		{0, 0, QIC_150},			/* minor 8-11 */
172 		{0, 0, QIC_120}				/* minor 12-15 */
173 	}}},
174 	/*
175 	 * At least -005 and -007 need this.  I'll assume they all do unless I
176 	 * hear otherwise.  - mycroft, 31MAR1994
177 	 */
178 	{{T_SEQUENTIAL, T_REMOV,
179 	 "ARCHIVE ", "VIPER 2525 25462", ""},     {0, 0, {
180 		{ST_Q_SENSE_HELP, 0, 0},		/* minor 0-3 */
181 		{ST_Q_SENSE_HELP, 0, QIC_525},		/* minor 4-7 */
182 		{0, 0, QIC_150},			/* minor 8-11 */
183 		{0, 0, QIC_120}				/* minor 12-15 */
184 	}}},
185 	/*
186 	 * One user reports that this works for his tape drive.  It probably
187 	 * needs more work.  - mycroft, 09APR1994
188 	 */
189 	{{T_SEQUENTIAL, T_REMOV,
190 	 "SANKYO  ", "CP525           ", ""},    {0, 0, {
191 		{ST_Q_FORCE_BLKSIZE, 512, 0},		/* minor 0-3 */
192 		{ST_Q_FORCE_BLKSIZE, 512, QIC_525},	/* minor 4-7 */
193 		{0, 0, QIC_150},			/* minor 8-11 */
194 		{0, 0, QIC_120}				/* minor 12-15 */
195 	}}},
196 	{{T_SEQUENTIAL, T_REMOV,
197 	 "ANRITSU ", "DMT780          ", ""},     {0, 0, {
198 		{ST_Q_FORCE_BLKSIZE, 512, 0},		/* minor 0-3 */
199 		{ST_Q_FORCE_BLKSIZE, 512, QIC_525},	/* minor 4-7 */
200 		{0, 0, QIC_150},			/* minor 8-11 */
201 		{0, 0, QIC_120}				/* minor 12-15 */
202 	}}},
203 	{{T_SEQUENTIAL, T_REMOV,
204 	 "ARCHIVE ", "VIPER 150  21247", ""},     {ST_Q_ERASE_NOIMM, 12, {
205 		{ST_Q_SENSE_HELP, 0, 0},		/* minor 0-3 */
206 		{0, 0, QIC_150},			/* minor 4-7 */
207 		{0, 0, QIC_120},			/* minor 8-11 */
208 		{0, 0, QIC_24}				/* minor 12-15 */
209 	}}},
210 	{{T_SEQUENTIAL, T_REMOV,
211 	 "ARCHIVE ", "VIPER 150  21531", ""},     {ST_Q_ERASE_NOIMM, 12, {
212 		{ST_Q_SENSE_HELP, 0, 0},		/* minor 0-3 */
213 		{0, 0, QIC_150},			/* minor 4-7 */
214 		{0, 0, QIC_120},			/* minor 8-11 */
215 		{0, 0, QIC_24}				/* minor 12-15 */
216 	}}},
217 	{{T_SEQUENTIAL, T_REMOV,
218 	 "WANGTEK ", "5099ES SCSI", ""},          {0, 0, {
219 		{ST_Q_FORCE_BLKSIZE, 512, 0},		/* minor 0-3 */
220 		{0, 0, QIC_11},				/* minor 4-7 */
221 		{0, 0, QIC_24},				/* minor 8-11 */
222 		{0, 0, QIC_24}				/* minor 12-15 */
223 	}}},
224 	{{T_SEQUENTIAL, T_REMOV,
225 	 "WANGTEK ", "5150ES SCSI", ""},          {0, 0, {
226 		{ST_Q_FORCE_BLKSIZE, 512, 0},		/* minor 0-3 */
227 		{0, 0, QIC_24},				/* minor 4-7 */
228 		{0, 0, QIC_120},			/* minor 8-11 */
229 		{0, 0, QIC_150}				/* minor 12-15 */
230 	}}},
231 	{{T_SEQUENTIAL, T_REMOV,
232 	 "WANGTEK ", "5525ES SCSI REV7", ""},     {0, 0, {
233 		{0, 0, 0},				/* minor 0-3 */
234 		{ST_Q_BLKSIZE, 0, QIC_525},		/* minor 4-7 */
235 		{0, 0, QIC_150},			/* minor 8-11 */
236 		{0, 0, QIC_120}				/* minor 12-15 */
237 	}}},
238 	{{T_SEQUENTIAL, T_REMOV,
239 	 "WangDAT ", "Model 1300      ", ""},     {0, 0, {
240 		{0, 0, 0},				/* minor 0-3 */
241 		{ST_Q_FORCE_BLKSIZE, 512, DDS},		/* minor 4-7 */
242 		{ST_Q_FORCE_BLKSIZE, 1024, DDS},	/* minor 8-11 */
243 		{ST_Q_FORCE_BLKSIZE, 0, DDS}		/* minor 12-15 */
244 	}}},
245 	{{T_SEQUENTIAL, T_REMOV,
246 	 "EXABYTE ", "EXB-8200        ", "263H"}, {0, 5, {
247 		{0, 0, 0},				/* minor 0-3 */
248 		{0, 0, 0},				/* minor 4-7 */
249 		{0, 0, 0},				/* minor 8-11 */
250 		{0, 0, 0}				/* minor 12-15 */
251 	}}},
252 	{{T_SEQUENTIAL, T_REMOV,
253 	 "STK",      "9490",             ""},
254 				{ST_Q_FORCE_BLKSIZE, 0, {
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",      "SD-3",             ""},
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 	 "IBM",      "03590",            ""},     {ST_Q_IGNORE_LOADS, 0, {
270 		{0, 0, 0},				/* minor 0-3 */
271 		{0, 0, 0},				/* minor 4-7 */
272 		{0, 0, 0},				/* minor 8-11 */
273 		{0, 0, 0}				/* minor 12-15 */
274 	}}},
275 	{{T_SEQUENTIAL, T_REMOV,
276 	 "HP      ", "T4000s          ", ""},     {ST_Q_UNIMODAL, 0, {
277 		{0, 0, QIC_3095},			/* minor 0-3 */
278 		{0, 0, QIC_3095},			/* minor 4-7 */
279 		{0, 0, QIC_3095},			/* minor 8-11 */
280 		{0, 0, QIC_3095},			/* minor 12-15 */
281 	}}},
282 #if 0
283 	{{T_SEQUENTIAL, T_REMOV,
284 	 "EXABYTE ", "EXB-8200        ", ""},     {0, 12, {
285 		{0, 0, 0},				/* minor 0-3 */
286 		{0, 0, 0},				/* minor 4-7 */
287 		{0, 0, 0},				/* minor 8-11 */
288 		{0, 0, 0}				/* minor 12-15 */
289 	}}},
290 #endif
291 	{{T_SEQUENTIAL, T_REMOV,
292 	 "TEAC    ", "MT-2ST/N50      ", ""},     {ST_Q_IGNORE_LOADS, 0, {
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 	{{T_SEQUENTIAL, T_REMOV,
299 	 "OnStream", "ADR50 Drive", ""},	  {ST_Q_UNIMODAL, 0, {
300 		{ST_Q_FORCE_BLKSIZE, 512, 0},	        /* minor 0-3 */
301 		{ST_Q_FORCE_BLKSIZE, 512, 0},	        /* minor 4-7 */
302 		{ST_Q_FORCE_BLKSIZE, 512, 0},	        /* minor 8-11 */
303 		{ST_Q_FORCE_BLKSIZE, 512, 0},	        /* minor 12-15 */
304 	}}},
305 	{{T_SEQUENTIAL, T_REMOV,
306 	 "OnStream DI-30",      "",   "1.0"},  {ST_Q_NOFILEMARKS, 0, {
307 		{0, 0, 0},                              /* minor 0-3 */
308 		{0, 0, 0},                              /* minor 4-7 */
309 		{0, 0, 0},                              /* minor 8-11 */
310 		{0, 0, 0}                               /* minor 12-15 */
311 	}}},
312 	{{T_SEQUENTIAL, T_REMOV,
313 	 "NCR H621", "0-STD-03-46F880 ", ""},     {ST_Q_NOPREVENT, 0, {
314 		{0, 0, 0},			       /* minor 0-3 */
315 		{0, 0, 0},			       /* minor 4-7 */
316 		{0, 0, 0},			       /* minor 8-11 */
317 		{0, 0, 0}			       /* minor 12-15 */
318 	}}},
319 };
320 
321 #define NOEJECT 0
322 #define EJECT 1
323 
324 static void	st_identify_drive(struct st_softc *,
325 		    struct scsipi_inquiry_pattern *);
326 static void	st_loadquirks(struct st_softc *);
327 static int	st_mount_tape(dev_t, int);
328 static void	st_unmount(struct st_softc *, boolean);
329 static int	st_decide_mode(struct st_softc *, boolean);
330 static void	ststart(struct scsipi_periph *);
331 static void	strestart(void *);
332 static void	stdone(struct scsipi_xfer *, int);
333 static int	st_read(struct st_softc *, char *, int, int);
334 static int	st_space(struct st_softc *, int, u_int, int);
335 static int	st_write_filemarks(struct st_softc *, int, int);
336 static int	st_check_eod(struct st_softc *, boolean, int *, int);
337 static int	st_load(struct st_softc *, u_int, int);
338 static int	st_rewind(struct st_softc *, u_int, int);
339 static int	st_interpret_sense(struct scsipi_xfer *);
340 static int	st_touch_tape(struct st_softc *);
341 static int	st_erase(struct st_softc *, int full, int flags);
342 static int	st_rdpos(struct st_softc *, int, u_int32_t *);
343 static int	st_setpos(struct st_softc *, int, u_int32_t *);
344 
345 static const struct scsipi_periphsw st_switch = {
346 	st_interpret_sense,
347 	ststart,
348 	NULL,
349 	stdone
350 };
351 
352 #if	defined(ST_ENABLE_EARLYWARN)
353 #define	ST_INIT_FLAGS	ST_EARLYWARN
354 #else
355 #define	ST_INIT_FLAGS	0
356 #endif
357 
358 /*
359  * The routine called by the low level scsi routine when it discovers
360  * A device suitable for this driver
361  */
362 void
363 stattach(struct device *parent, struct st_softc *st, void *aux)
364 {
365 	struct scsipibus_attach_args *sa = aux;
366 	struct scsipi_periph *periph = sa->sa_periph;
367 
368 	SC_DEBUG(periph, SCSIPI_DB2, ("stattach: "));
369 
370 	/*
371 	 * Store information needed to contact our base driver
372 	 */
373 	st->sc_periph = periph;
374 	periph->periph_dev = &st->sc_dev;
375 	periph->periph_switch = &st_switch;
376 
377 	/*
378 	 * Set initial flags
379 	 */
380 
381 	st->flags = ST_INIT_FLAGS;
382 
383 	/*
384 	 * Set up the buf queue for this device
385 	 */
386 	bufq_alloc(&st->buf_queue, "fcfs", 0);
387 
388 	callout_init(&st->sc_callout);
389 
390 	/*
391 	 * Check if the drive is a known criminal and take
392 	 * Any steps needed to bring it into line
393 	 */
394 	st_identify_drive(st, &sa->sa_inqbuf);
395 	/*
396 	 * Use the subdriver to request information regarding the drive.
397 	 */
398 	printf("\n");
399 	printf("%s: %s", st->sc_dev.dv_xname, st->quirkdata ? "quirks apply, " : "");
400 	if (scsipi_test_unit_ready(periph,
401 	    XS_CTL_DISCOVERY | XS_CTL_SILENT | XS_CTL_IGNORE_MEDIA_CHANGE) ||
402 	    st->ops(st, ST_OPS_MODESENSE,
403 	    XS_CTL_DISCOVERY | XS_CTL_SILENT | XS_CTL_IGNORE_MEDIA_CHANGE))
404 		printf("drive empty\n");
405 	else {
406 		printf("density code %d, ", st->media_density);
407 		if (st->media_blksize > 0)
408 			printf("%d-byte", st->media_blksize);
409 		else
410 			printf("variable");
411 		printf(" blocks, write-%s\n",
412 		    (st->flags & ST_READONLY) ? "protected" : "enabled");
413 	}
414 
415 	st->stats = iostat_alloc(IOSTAT_TAPE);
416 	st->stats->io_name = st->sc_dev.dv_xname;
417 
418 #if NRND > 0
419 	rnd_attach_source(&st->rnd_source, st->sc_dev.dv_xname,
420 			  RND_TYPE_TAPE, 0);
421 #endif
422 }
423 
424 int
425 stactivate(struct device *self, enum devact act)
426 {
427 	int rv = 0;
428 
429 	switch (act) {
430 	case DVACT_ACTIVATE:
431 		rv = EOPNOTSUPP;
432 		break;
433 
434 	case DVACT_DEACTIVATE:
435 		/*
436 		 * Nothing to do; we key off the device's DVF_ACTIVE.
437 		 */
438 		break;
439 	}
440 	return (rv);
441 }
442 
443 int
444 stdetach(struct device *self, int flags)
445 {
446 	struct st_softc *st = device_private(self);
447 	int s, bmaj, cmaj, mn;
448 
449 	/* locate the major number */
450 	bmaj = bdevsw_lookup_major(&st_bdevsw);
451 	cmaj = cdevsw_lookup_major(&st_cdevsw);
452 
453 	/* kill any pending restart */
454 	callout_stop(&st->sc_callout);
455 
456 	s = splbio();
457 
458 	/* Kill off any queued buffers. */
459 	bufq_drain(st->buf_queue);
460 
461 	bufq_free(st->buf_queue);
462 
463 	/* Kill off any pending commands. */
464 	scsipi_kill_pending(st->sc_periph);
465 
466 	splx(s);
467 
468 	/* Nuke the vnodes for any open instances */
469 	mn = STUNIT(device_unit(self));
470 	vdevgone(bmaj, mn, mn+STNMINOR-1, VBLK);
471 	vdevgone(cmaj, mn, mn+STNMINOR-1, VCHR);
472 
473 	iostat_free(st->stats);
474 
475 #if NRND > 0
476 	/* Unhook the entropy source. */
477 	rnd_detach_source(&st->rnd_source);
478 #endif
479 
480 	return (0);
481 }
482 
483 /*
484  * Use the inquiry routine in 'scsi_base' to get drive info so we can
485  * Further tailor our behaviour.
486  */
487 static void
488 st_identify_drive(struct st_softc *st, struct scsipi_inquiry_pattern *inqbuf)
489 {
490 	const struct st_quirk_inquiry_pattern *finger;
491 	int priority;
492 
493 	finger = scsipi_inqmatch(inqbuf,
494 	    st_quirk_patterns,
495 	    sizeof(st_quirk_patterns) / sizeof(st_quirk_patterns[0]),
496 	    sizeof(st_quirk_patterns[0]), &priority);
497 	if (priority != 0) {
498 		st->quirkdata = &finger->quirkdata;
499 		st->drive_quirks = finger->quirkdata.quirks;
500 		st->quirks = finger->quirkdata.quirks;	/* start value */
501 		st->page_0_size = finger->quirkdata.page_0_size;
502 		st_loadquirks(st);
503 	}
504 }
505 
506 /*
507  * initialise the subdevices to the default (QUIRK) state.
508  * this will remove any setting made by the system operator or previous
509  * operations.
510  */
511 static void
512 st_loadquirks(struct st_softc *st)
513 {
514 	int i;
515 	const struct	modes *mode;
516 	struct	modes *mode2;
517 
518 	mode = st->quirkdata->modes;
519 	mode2 = st->modes;
520 	for (i = 0; i < 4; i++) {
521 		memset(mode2, 0, sizeof(struct modes));
522 		st->modeflags[i] &= ~(BLKSIZE_SET_BY_QUIRK |
523 		    DENSITY_SET_BY_QUIRK | BLKSIZE_SET_BY_USER |
524 		    DENSITY_SET_BY_USER);
525 		if ((mode->quirks | st->drive_quirks) & ST_Q_FORCE_BLKSIZE) {
526 			mode2->blksize = mode->blksize;
527 			st->modeflags[i] |= BLKSIZE_SET_BY_QUIRK;
528 		}
529 		if (mode->density) {
530 			mode2->density = mode->density;
531 			st->modeflags[i] |= DENSITY_SET_BY_QUIRK;
532 		}
533 		mode2->quirks |= mode->quirks;
534 		mode++;
535 		mode2++;
536 	}
537 }
538 
539 /*
540  * open the device.
541  */
542 static int
543 stopen(dev_t dev, int flags, int mode, struct lwp *l)
544 {
545 	u_int stmode, dsty;
546 	int error, sflags, unit, tries, ntries;
547 	struct st_softc *st;
548 	struct scsipi_periph *periph;
549 	struct scsipi_adapter *adapt;
550 
551 	unit = STUNIT(dev);
552 	if (unit >= st_cd.cd_ndevs)
553 		return (ENXIO);
554 	st = st_cd.cd_devs[unit];
555 	if (st == NULL)
556 		return (ENXIO);
557 
558 	stmode = STMODE(dev);
559 	dsty = STDSTY(dev);
560 
561 	periph = st->sc_periph;
562 	adapt = periph->periph_channel->chan_adapter;
563 
564 	SC_DEBUG(periph, SCSIPI_DB1, ("open: dev=0x%x (unit %d (of %d))\n", dev,
565 	    unit, st_cd.cd_ndevs));
566 
567 
568 	/*
569 	 * Only allow one at a time
570 	 */
571 	if (periph->periph_flags & PERIPH_OPEN) {
572 		printf("%s: already open\n", st->sc_dev.dv_xname);
573 		return (EBUSY);
574 	}
575 
576 	if ((error = scsipi_adapter_addref(adapt)) != 0)
577 		return (error);
578 
579 	/*
580 	 * clear any latched errors.
581 	 */
582 	st->mt_resid = 0;
583 	st->mt_erreg = 0;
584 	st->asc = 0;
585 	st->ascq = 0;
586 
587 	/*
588 	 * Catch any unit attention errors. Be silent about this
589 	 * unless we're already mounted. We ignore media change
590 	 * if we're in control mode or not mounted yet.
591 	 */
592 	if ((st->flags & ST_MOUNTED) == 0 || stmode == CTRL_MODE) {
593 #ifdef SCSIDEBUG
594 		sflags = XS_CTL_IGNORE_MEDIA_CHANGE;
595 #else
596 		sflags = XS_CTL_SILENT|XS_CTL_IGNORE_MEDIA_CHANGE;
597 #endif
598 	} else
599 		sflags = 0;
600 
601 	/*
602 	 * If we're already mounted or we aren't configured for
603 	 * a mount delay, only try a test unit ready once. Otherwise,
604 	 * try up to ST_MOUNT_DELAY times with a rest interval of
605 	 * one second between each try.
606 	 */
607 
608 	if ((st->flags & ST_MOUNTED) || ST_MOUNT_DELAY == 0) {
609 		ntries = 1;
610 	} else {
611 		ntries = ST_MOUNT_DELAY;
612 	}
613 
614 	for (error = tries = 0; tries < ntries; tries++) {
615 		int slpintr, oflags;
616 
617 		/*
618 		 * If we had no error, or we're opening the control mode
619 		 * device, we jump out right away.
620 		 */
621 
622 		error = scsipi_test_unit_ready(periph, sflags);
623 		if (error == 0 || stmode == CTRL_MODE) {
624 			break;
625 		}
626 
627 		/*
628 		 * We had an error.
629 		 *
630 		 * If we're already mounted or we aren't configured for
631 		 * a mount delay, or the error isn't a NOT READY error,
632 		 * skip to the error exit now.
633 		 */
634 		if ((st->flags & ST_MOUNTED) || ST_MOUNT_DELAY == 0 ||
635 		    (st->mt_key != SKEY_NOT_READY)) {
636 			goto bad;
637 		}
638 
639 		/*
640 		 * clear any latched errors.
641 		 */
642 		st->mt_resid = 0;
643 		st->mt_erreg = 0;
644 		st->asc = 0;
645 		st->ascq = 0;
646 
647 		/*
648 		 * Fake that we have the device open so
649 		 * we block other apps from getting in.
650 		 */
651 
652 		oflags = periph->periph_flags;
653 		periph->periph_flags |= PERIPH_OPEN;
654 
655 		slpintr = tsleep(&lbolt, PUSER|PCATCH, "stload", 0);
656 
657 		periph->periph_flags = oflags;	/* restore flags */
658 		if (slpintr) {
659 			goto bad;
660 		}
661 	}
662 
663 
664 	/*
665 	 * If the mode is 3 (e.g. minor = 3,7,11,15) then the device has
666 	 * been opened to set defaults and perform other, usually non-I/O
667 	 * related, operations. In this case, do a quick check to see
668 	 * whether the unit actually had a tape loaded (this will be known
669 	 * as to whether or not we got a NOT READY for the above
670 	 * unit attention). If a tape is there, go do a mount sequence.
671 	 */
672 	if (stmode == CTRL_MODE && st->mt_key == SKEY_NOT_READY) {
673 		periph->periph_flags |= PERIPH_OPEN;
674 		return (0);
675 	}
676 
677 	/*
678 	 * If we get this far and had an error set, that means we failed
679 	 * to pass the 'test unit ready' test for the non-controlmode device,
680 	 * so we bounce the open.
681 	 */
682 
683 	if (error)
684 		return (error);
685 
686 	/*
687 	 * Else, we're now committed to saying we're open.
688 	 */
689 
690 	periph->periph_flags |= PERIPH_OPEN; /* unit attn are now errors */
691 
692 	/*
693 	 * If it's a different mode, or if the media has been
694 	 * invalidated, unmount the tape from the previous
695 	 * session but continue with open processing
696 	 */
697 	if (st->last_dsty != dsty ||
698 	    (periph->periph_flags & PERIPH_MEDIA_LOADED) == 0)
699 		st_unmount(st, NOEJECT);
700 
701 	/*
702 	 * If we are not mounted, then we should start a new
703 	 * mount session.
704 	 */
705 	if (!(st->flags & ST_MOUNTED)) {
706 		if ((error = st_mount_tape(dev, flags)) != 0)
707 			goto bad;
708 		st->last_dsty = dsty;
709 	}
710 	if (!(st->quirks & ST_Q_NOPREVENT)) {
711 		scsipi_prevent(periph, SPAMR_PREVENT_DT,
712 		    XS_CTL_IGNORE_ILLEGAL_REQUEST | XS_CTL_IGNORE_NOT_READY);
713 	}
714 
715 	SC_DEBUG(periph, SCSIPI_DB2, ("open complete\n"));
716 	return (0);
717 
718 bad:
719 	st_unmount(st, NOEJECT);
720 	scsipi_adapter_delref(adapt);
721 	periph->periph_flags &= ~PERIPH_OPEN;
722 	return (error);
723 }
724 
725 /*
726  * close the device.. only called if we are the LAST
727  * occurence of an open device
728  */
729 static int
730 stclose(dev_t dev, int flags, int mode, struct lwp *l)
731 {
732 	int stxx, error = 0;
733 	struct st_softc *st = st_cd.cd_devs[STUNIT(dev)];
734 	struct scsipi_periph *periph = st->sc_periph;
735 	struct scsipi_adapter *adapt = periph->periph_channel->chan_adapter;
736 
737 	SC_DEBUG(st->sc_periph, SCSIPI_DB1, ("closing\n"));
738 
739 	/*
740 	 * Make sure that a tape opened in write-only mode will have
741 	 * file marks written on it when closed, even if not written to.
742 	 *
743 	 * This is for SUN compatibility. Actually, the Sun way of
744 	 * things is to:
745 	 *
746 	 *	only write filemarks if there are fmks to be written and
747 	 *   		- open for write (possibly read/write)
748 	 *		- the last operation was a write
749 	 * 	or:
750 	 *		- opened for wronly
751 	 *		- no data was written (including filemarks)
752 	 */
753 
754 	stxx = st->flags & (ST_WRITTEN | ST_FM_WRITTEN);
755 	if (((flags & FWRITE) && stxx == ST_WRITTEN) ||
756 	    ((flags & O_ACCMODE) == FWRITE && stxx == 0)) {
757 		int nm;
758 		error = st_check_eod(st, FALSE, &nm, 0);
759 	}
760 
761 	/*
762 	 * Allow robots to eject tape if needed.
763 	 */
764 	scsipi_prevent(periph, SPAMR_ALLOW,
765 	    XS_CTL_IGNORE_ILLEGAL_REQUEST | XS_CTL_IGNORE_NOT_READY);
766 
767 	switch (STMODE(dev)) {
768 	case NORMAL_MODE:
769 		st_unmount(st, NOEJECT);
770 		break;
771 	case NOREW_MODE:
772 	case CTRL_MODE:
773 		/*
774 		 * Leave mounted unless media seems to have been removed.
775 		 *
776 		 * Otherwise, if we're to terminate a tape with more than one
777 		 * filemark [ and because we're not rewinding here ], backspace
778 		 * one filemark so that later appends will see an unbroken
779 		 * sequence of:
780 		 *
781 		 *	file - FMK - file - FMK ... file - FMK FMK (EOM)
782 		 */
783 		if ((periph->periph_flags & PERIPH_MEDIA_LOADED) == 0) {
784 			st_unmount(st, NOEJECT);
785 		} else if (error == 0) {
786 			/*
787 			 * ST_WRITTEN was preserved from above.
788 			 *
789 			 * All we need to know here is:
790 			 *
791 			 *	Were we writing this tape and was the last
792 			 *	operation a write?
793 			 *
794 			 *	Are there supposed to be 2FM at EOD?
795 			 *
796 			 * If both statements are true, then we backspace
797 			 * one filemark.
798 			 */
799 			stxx |= (st->flags & ST_2FM_AT_EOD);
800 			if ((flags & FWRITE) != 0 &&
801 			    (stxx == (ST_2FM_AT_EOD|ST_WRITTEN))) {
802 				error = st_space(st, -1, SP_FILEMARKS, 0);
803 			}
804 		}
805 		break;
806 	case EJECT_MODE:
807 		st_unmount(st, EJECT);
808 		break;
809 	}
810 
811 	scsipi_wait_drain(periph);
812 
813 	scsipi_adapter_delref(adapt);
814 	periph->periph_flags &= ~PERIPH_OPEN;
815 
816 	return (error);
817 }
818 
819 /*
820  * Start a new mount session.
821  * Copy in all the default parameters from the selected device mode.
822  * and try guess any that seem to be defaulted.
823  */
824 static int
825 st_mount_tape(dev_t dev, int flags)
826 {
827 	int unit;
828 	u_int dsty;
829 	struct st_softc *st;
830 	struct scsipi_periph *periph;
831 	int error = 0;
832 
833 	unit = STUNIT(dev);
834 	dsty = STDSTY(dev);
835 	st = st_cd.cd_devs[unit];
836 	periph = st->sc_periph;
837 
838 	if (st->flags & ST_MOUNTED)
839 		return (0);
840 
841 	SC_DEBUG(periph, SCSIPI_DB1, ("mounting\n "));
842 	st->flags |= ST_NEW_MOUNT;
843 	st->quirks = st->drive_quirks | st->modes[dsty].quirks;
844 	/*
845 	 * If the media is new, then make sure we give it a chance to
846 	 * to do a 'load' instruction.  (We assume it is new.)
847 	 */
848 	if ((error = st_load(st, LD_LOAD, XS_CTL_SILENT)) != 0)
849 		return (error);
850 	/*
851 	 * Throw another dummy instruction to catch
852 	 * 'Unit attention' errors. Many drives give
853 	 * these after doing a Load instruction (with
854 	 * the MEDIUM MAY HAVE CHANGED asc/ascq).
855 	 */
856 	scsipi_test_unit_ready(periph, XS_CTL_SILENT);	/* XXX */
857 
858 	/*
859 	 * Some devices can't tell you much until they have been
860 	 * asked to look at the media. This quirk does this.
861 	 */
862 	if (st->quirks & ST_Q_SENSE_HELP)
863 		if ((error = st_touch_tape(st)) != 0)
864 			return (error);
865 	/*
866 	 * Load the physical device parameters
867 	 * loads: blkmin, blkmax
868 	 */
869 	if ((error = st->ops(st, ST_OPS_RBL, 0)) != 0)
870 		return (error);
871 	/*
872 	 * Load the media dependent parameters
873 	 * includes: media_blksize,media_density,numblks
874 	 * As we have a tape in, it should be reflected here.
875 	 * If not you may need the "quirk" above.
876 	 */
877 	if ((error = st->ops(st, ST_OPS_MODESENSE, 0)) != 0)
878 		return (error);
879 	/*
880 	 * If we have gained a permanent density from somewhere,
881 	 * then use it in preference to the one supplied by
882 	 * default by the driver.
883 	 */
884 	if (st->modeflags[dsty] & (DENSITY_SET_BY_QUIRK | DENSITY_SET_BY_USER))
885 		st->density = st->modes[dsty].density;
886 	else
887 		st->density = st->media_density;
888 	/*
889 	 * If we have gained a permanent blocksize
890 	 * then use it in preference to the one supplied by
891 	 * default by the driver.
892 	 */
893 	st->flags &= ~ST_FIXEDBLOCKS;
894 	if (st->modeflags[dsty] &
895 	    (BLKSIZE_SET_BY_QUIRK | BLKSIZE_SET_BY_USER)) {
896 		st->blksize = st->modes[dsty].blksize;
897 		if (st->blksize)
898 			st->flags |= ST_FIXEDBLOCKS;
899 	} else {
900 		if ((error = st_decide_mode(st, FALSE)) != 0)
901 			return (error);
902 	}
903 	if ((error = st->ops(st, ST_OPS_MODESELECT, 0)) != 0) {
904 		/* ATAPI will return ENODEV for this, and this may be OK */
905 		if (error != ENODEV) {
906 			printf("%s: cannot set selected mode\n",
907 			    st->sc_dev.dv_xname);
908 			return (error);
909 		}
910 	}
911 	st->flags &= ~ST_NEW_MOUNT;
912 	st->flags |= ST_MOUNTED;
913 	periph->periph_flags |= PERIPH_MEDIA_LOADED;	/* move earlier? */
914 	st->blkno = st->fileno = (daddr_t) 0;
915 	return (0);
916 }
917 
918 /*
919  * End the present mount session.
920  * Rewind, and optionally eject the tape.
921  * Reset various flags to indicate that all new
922  * operations require another mount operation
923  */
924 static void
925 st_unmount(struct st_softc *st, boolean eject)
926 {
927 	struct scsipi_periph *periph = st->sc_periph;
928 	int nmarks;
929 
930 	if ((st->flags & ST_MOUNTED) == 0)
931 		return;
932 	SC_DEBUG(periph, SCSIPI_DB1, ("unmounting\n"));
933 	st_check_eod(st, FALSE, &nmarks, XS_CTL_IGNORE_NOT_READY);
934 	st_rewind(st, 0, XS_CTL_IGNORE_NOT_READY);
935 
936 	/*
937 	 * Section 9.3.3 of the SCSI specs states that a device shall return
938 	 * the density value specified in the last succesfull MODE SELECT
939 	 * after an unload operation, in case it is not able to
940 	 * automatically determine the density of the new medium.
941 	 *
942 	 * So we instruct the device to use the default density, which will
943 	 * prevent the use of stale density values (in particular,
944 	 * in st_touch_tape().
945 	 */
946 	st->density = 0;
947 	if (st->ops(st, ST_OPS_MODESELECT, 0) != 0) {
948 		printf("%s: WARNING: cannot revert to default density\n",
949 			st->sc_dev.dv_xname);
950 	}
951 
952 	if (eject) {
953 		if (!(st->quirks & ST_Q_NOPREVENT)) {
954 			scsipi_prevent(periph, SPAMR_ALLOW,
955 			    XS_CTL_IGNORE_ILLEGAL_REQUEST |
956 			    XS_CTL_IGNORE_NOT_READY);
957 		}
958 		st_load(st, LD_UNLOAD, XS_CTL_IGNORE_NOT_READY);
959 		st->blkno = st->fileno = (daddr_t) -1;
960 	} else {
961 		st->blkno = st->fileno = (daddr_t) 0;
962 	}
963 	st->flags &= ~(ST_MOUNTED | ST_NEW_MOUNT);
964 	periph->periph_flags &= ~PERIPH_MEDIA_LOADED;
965 }
966 
967 /*
968  * Given all we know about the device, media, mode, 'quirks' and
969  * initial operation, make a decision as to how we should be set
970  * to run (regarding blocking and EOD marks)
971  */
972 int
973 st_decide_mode(struct st_softc *st, boolean first_read)
974 {
975 
976 	SC_DEBUG(st->sc_periph, SCSIPI_DB2, ("starting block mode decision\n"));
977 
978 	/*
979 	 * If the drive can only handle fixed-length blocks and only at
980 	 * one size, perhaps we should just do that.
981 	 */
982 	if (st->blkmin && (st->blkmin == st->blkmax)) {
983 		st->flags |= ST_FIXEDBLOCKS;
984 		st->blksize = st->blkmin;
985 		SC_DEBUG(st->sc_periph, SCSIPI_DB3,
986 		    ("blkmin == blkmax of %d\n", st->blkmin));
987 		goto done;
988 	}
989 	/*
990 	 * If the tape density mandates (or even suggests) use of fixed
991 	 * or variable-length blocks, comply.
992 	 */
993 	switch (st->density) {
994 	case HALFINCH_800:
995 	case HALFINCH_1600:
996 	case HALFINCH_6250:
997 	case DDS:
998 		st->flags &= ~ST_FIXEDBLOCKS;
999 		st->blksize = 0;
1000 		SC_DEBUG(st->sc_periph, SCSIPI_DB3,
1001 		    ("density specified variable\n"));
1002 		goto done;
1003 	case QIC_11:
1004 	case QIC_24:
1005 	case QIC_120:
1006 	case QIC_150:
1007 	case QIC_525:
1008 	case QIC_1320:
1009 	case QIC_3095:
1010 	case QIC_3220:
1011 		st->flags |= ST_FIXEDBLOCKS;
1012 		if (st->media_blksize > 0)
1013 			st->blksize = st->media_blksize;
1014 		else
1015 			st->blksize = DEF_FIXED_BSIZE;
1016 		SC_DEBUG(st->sc_periph, SCSIPI_DB3,
1017 		    ("density specified fixed\n"));
1018 		goto done;
1019 	}
1020 	/*
1021 	 * If we're about to read the tape, perhaps we should choose
1022 	 * fixed or variable-length blocks and block size according to
1023 	 * what the drive found on the tape.
1024 	 */
1025 	if (first_read &&
1026 	    (!(st->quirks & ST_Q_BLKSIZE) || (st->media_blksize == 0) ||
1027 	    (st->media_blksize == DEF_FIXED_BSIZE) ||
1028 	    (st->media_blksize == 1024))) {
1029 		if (st->media_blksize > 0)
1030 			st->flags |= ST_FIXEDBLOCKS;
1031 		else
1032 			st->flags &= ~ST_FIXEDBLOCKS;
1033 		st->blksize = st->media_blksize;
1034 		SC_DEBUG(st->sc_periph, SCSIPI_DB3,
1035 		    ("Used media_blksize of %d\n", st->media_blksize));
1036 		goto done;
1037 	}
1038 	/*
1039 	 * We're getting no hints from any direction.  Choose variable-
1040 	 * length blocks arbitrarily.
1041 	 */
1042 	st->flags &= ~ST_FIXEDBLOCKS;
1043 	st->blksize = 0;
1044 	SC_DEBUG(st->sc_periph, SCSIPI_DB3,
1045 	    ("Give up and default to variable mode\n"));
1046 
1047 done:
1048 	/*
1049 	 * Decide whether or not to write two file marks to signify end-
1050 	 * of-data.  Make the decision as a function of density.  If
1051 	 * the decision is not to use a second file mark, the SCSI BLANK
1052 	 * CHECK condition code will be recognized as end-of-data when
1053 	 * first read.
1054 	 * (I think this should be a by-product of fixed/variable..julian)
1055 	 */
1056 	switch (st->density) {
1057 /*      case 8 mm:   What is the SCSI density code for 8 mm, anyway? */
1058 	case QIC_11:
1059 	case QIC_24:
1060 	case QIC_120:
1061 	case QIC_150:
1062 	case QIC_525:
1063 	case QIC_1320:
1064 	case QIC_3095:
1065 	case QIC_3220:
1066 		st->flags &= ~ST_2FM_AT_EOD;
1067 		break;
1068 	default:
1069 		st->flags |= ST_2FM_AT_EOD;
1070 	}
1071 	return (0);
1072 }
1073 
1074 /*
1075  * Actually translate the requested transfer into
1076  * one the physical driver can understand
1077  * The transfer is described by a buf and will include
1078  * only one physical transfer.
1079  */
1080 static void
1081 ststrategy(struct buf *bp)
1082 {
1083 	struct st_softc *st = st_cd.cd_devs[STUNIT(bp->b_dev)];
1084 	int s;
1085 
1086 	SC_DEBUG(st->sc_periph, SCSIPI_DB1,
1087 	    ("ststrategy %d bytes @ blk %" PRId64 "\n", bp->b_bcount, bp->b_blkno));
1088 	/*
1089 	 * If it's a null transfer, return immediatly
1090 	 */
1091 	if (bp->b_bcount == 0)
1092 		goto done;
1093 
1094 	/* If offset is negative, error */
1095 	if (bp->b_blkno < 0) {
1096 		bp->b_error = EINVAL;
1097 		goto bad;
1098 	}
1099 
1100 	/*
1101 	 * Odd sized request on fixed drives are verboten
1102 	 */
1103 	if (st->flags & ST_FIXEDBLOCKS) {
1104 		if (bp->b_bcount % st->blksize) {
1105 			printf("%s: bad request, must be multiple of %d\n",
1106 			    st->sc_dev.dv_xname, st->blksize);
1107 			bp->b_error = EIO;
1108 			goto bad;
1109 		}
1110 	}
1111 	/*
1112 	 * as are out-of-range requests on variable drives.
1113 	 */
1114 	else if (bp->b_bcount < st->blkmin ||
1115 	    (st->blkmax && bp->b_bcount > st->blkmax)) {
1116 		printf("%s: bad request, must be between %d and %d\n",
1117 		    st->sc_dev.dv_xname, st->blkmin, st->blkmax);
1118 		bp->b_error = EIO;
1119 		goto bad;
1120 	}
1121 	s = splbio();
1122 
1123 	/*
1124 	 * Place it in the queue of activities for this tape
1125 	 * at the end (a bit silly because we only have on user..
1126 	 * (but it could fork()))
1127 	 */
1128 	BUFQ_PUT(st->buf_queue, bp);
1129 
1130 	/*
1131 	 * Tell the device to get going on the transfer if it's
1132 	 * not doing anything, otherwise just wait for completion
1133 	 * (All a bit silly if we're only allowing 1 open but..)
1134 	 */
1135 	ststart(st->sc_periph);
1136 
1137 	splx(s);
1138 	return;
1139 bad:
1140 	bp->b_flags |= B_ERROR;
1141 done:
1142 	/*
1143 	 * Correctly set the buf to indicate a completed xfer
1144 	 */
1145 	bp->b_resid = bp->b_bcount;
1146 	biodone(bp);
1147 	return;
1148 }
1149 
1150 /*
1151  * ststart looks to see if there is a buf waiting for the device
1152  * and that the device is not already busy. If both are true,
1153  * It dequeues the buf and creates a scsi command to perform the
1154  * transfer required. The transfer request will call scsipi_done
1155  * on completion, which will in turn call this routine again
1156  * so that the next queued transfer is performed.
1157  * The bufs are queued by the strategy routine (ststrategy)
1158  *
1159  * This routine is also called after other non-queued requests
1160  * have been made of the scsi driver, to ensure that the queue
1161  * continues to be drained.
1162  * ststart() is called at splbio
1163  */
1164 static void
1165 ststart(struct scsipi_periph *periph)
1166 {
1167 	struct st_softc *st = (void *)periph->periph_dev;
1168 	struct buf *bp;
1169 	struct scsi_rw_tape cmd;
1170 	struct scsipi_xfer *xs;
1171 	int flags, error;
1172 
1173 	SC_DEBUG(periph, SCSIPI_DB2, ("ststart "));
1174 	/*
1175 	 * See if there is a buf to do and we are not already
1176 	 * doing one
1177 	 */
1178 	while (periph->periph_active < periph->periph_openings) {
1179 		/* if a special awaits, let it proceed first */
1180 		if (periph->periph_flags & PERIPH_WAITING) {
1181 			periph->periph_flags &= ~PERIPH_WAITING;
1182 			wakeup((caddr_t)periph);
1183 			return;
1184 		}
1185 
1186 		/*
1187 		 * If the device has been unmounted by the user
1188 		 * then throw away all requests until done.
1189 		 */
1190 		if (__predict_false((st->flags & ST_MOUNTED) == 0 ||
1191 		    (periph->periph_flags & PERIPH_MEDIA_LOADED) == 0)) {
1192 			if ((bp = BUFQ_GET(st->buf_queue)) != NULL) {
1193 				/* make sure that one implies the other.. */
1194 				periph->periph_flags &= ~PERIPH_MEDIA_LOADED;
1195 				bp->b_flags |= B_ERROR;
1196 				bp->b_error = EIO;
1197 				bp->b_resid = bp->b_bcount;
1198 				biodone(bp);
1199 				continue;
1200 			} else {
1201 				return;
1202 			}
1203 		}
1204 
1205 		if ((bp = BUFQ_PEEK(st->buf_queue)) == NULL)
1206 			return;
1207 
1208 		iostat_busy(st->stats);
1209 
1210 		/*
1211 		 * only FIXEDBLOCK devices have pending I/O or space operations.
1212 		 */
1213 		if (st->flags & ST_FIXEDBLOCKS) {
1214 			/*
1215 			 * If we are at a filemark but have not reported it yet
1216 			 * then we should report it now
1217 			 */
1218 			if (st->flags & ST_AT_FILEMARK) {
1219 				if ((bp->b_flags & B_READ) == B_WRITE) {
1220 					/*
1221 					 * Handling of ST_AT_FILEMARK in
1222 					 * st_space will fill in the right file
1223 					 * mark count.
1224 					 * Back up over filemark
1225 					 */
1226 					if (st_space(st, 0, SP_FILEMARKS, 0)) {
1227 						BUFQ_GET(st->buf_queue);
1228 						bp->b_flags |= B_ERROR;
1229 						bp->b_error = EIO;
1230 						biodone(bp);
1231 						continue;
1232 					}
1233 				} else {
1234 					BUFQ_GET(st->buf_queue);
1235 					bp->b_resid = bp->b_bcount;
1236 					bp->b_error = 0;
1237 					bp->b_flags &= ~B_ERROR;
1238 					st->flags &= ~ST_AT_FILEMARK;
1239 					biodone(bp);
1240 					continue;	/* seek more work */
1241 				}
1242 			}
1243 		}
1244 		/*
1245 		 * If we are at EOM but have not reported it
1246 		 * yet then we should report it now.
1247 		 */
1248 		if (st->flags & (ST_EOM_PENDING|ST_EIO_PENDING)) {
1249 			BUFQ_GET(st->buf_queue);
1250 			bp->b_resid = bp->b_bcount;
1251 			if (st->flags & ST_EIO_PENDING) {
1252 				bp->b_error = EIO;
1253 				bp->b_flags |= B_ERROR;
1254 			}
1255 			st->flags &= ~(ST_EOM_PENDING|ST_EIO_PENDING);
1256 			biodone(bp);
1257 			continue;	/* seek more work */
1258 		}
1259 
1260 		/*
1261 		 * Fill out the scsi command
1262 		 */
1263 		memset(&cmd, 0, sizeof(cmd));
1264 		flags = XS_CTL_NOSLEEP | XS_CTL_ASYNC;
1265 		if ((bp->b_flags & B_READ) == B_WRITE) {
1266 			cmd.opcode = WRITE;
1267 			st->flags &= ~ST_FM_WRITTEN;
1268 			flags |= XS_CTL_DATA_OUT;
1269 		} else {
1270 			cmd.opcode = READ;
1271 			flags |= XS_CTL_DATA_IN;
1272 		}
1273 
1274 		/*
1275 		 * Handle "fixed-block-mode" tape drives by using the
1276 		 * block count instead of the length.
1277 		 */
1278 		if (st->flags & ST_FIXEDBLOCKS) {
1279 			cmd.byte2 |= SRW_FIXED;
1280 			_lto3b(bp->b_bcount / st->blksize, cmd.len);
1281 		} else
1282 			_lto3b(bp->b_bcount, cmd.len);
1283 
1284 		/*
1285 		 * Clear 'position updated' indicator
1286 		 */
1287 		st->flags &= ~ST_POSUPDATED;
1288 
1289 		/*
1290 		 * go ask the adapter to do all this for us
1291 		 */
1292 		xs = scsipi_make_xs(periph,
1293 		    (struct scsipi_generic *)&cmd, sizeof(cmd),
1294 		    (u_char *)bp->b_data, bp->b_bcount,
1295 		    0, ST_IO_TIME, bp, flags);
1296 		if (__predict_false(xs == NULL)) {
1297 			/*
1298 			 * out of memory. Keep this buffer in the queue, and
1299 			 * retry later.
1300 			 */
1301 			callout_reset(&st->sc_callout, hz / 2, strestart,
1302 			    periph);
1303 			return;
1304 		}
1305 		/*
1306 		 * need to dequeue the buffer before queuing the command,
1307 		 * because cdstart may be called recursively from the
1308 		 * HBA driver
1309 		 */
1310 #ifdef DIAGNOSTIC
1311 		if (BUFQ_GET(st->buf_queue) != bp)
1312 			panic("ststart(): dequeued wrong buf");
1313 #else
1314 		BUFQ_GET(st->buf_queue);
1315 #endif
1316 		error = scsipi_execute_xs(xs);
1317 		/* with a scsipi_xfer preallocated, scsipi_command can't fail */
1318 		KASSERT(error == 0);
1319 	} /* go back and see if we can cram more work in.. */
1320 }
1321 
1322 static void
1323 strestart(void *v)
1324 {
1325 	int s = splbio();
1326 	ststart((struct scsipi_periph *)v);
1327 	splx(s);
1328 }
1329 
1330 
1331 static void
1332 stdone(struct scsipi_xfer *xs, int error)
1333 {
1334 	struct st_softc *st = (void *)xs->xs_periph->periph_dev;
1335 	struct buf *bp = xs->bp;
1336 
1337 	if (bp) {
1338 		bp->b_error = error;
1339 		bp->b_resid = xs->resid;
1340 		if (error)
1341 			bp->b_flags |= B_ERROR;
1342 
1343 		if ((bp->b_flags & B_READ) == B_WRITE)
1344 			st->flags |= ST_WRITTEN;
1345 		else
1346 			st->flags &= ~ST_WRITTEN;
1347 
1348 		iostat_unbusy(st->stats, bp->b_bcount,
1349 			     ((bp->b_flags & B_READ) == B_READ));
1350 
1351 #if NRND > 0
1352 		rnd_add_uint32(&st->rnd_source, bp->b_blkno);
1353 #endif
1354 
1355 		if ((st->flags & ST_POSUPDATED) == 0) {
1356 			if (error) {
1357 				st->fileno = st->blkno = -1;
1358 			} else if (st->blkno != -1) {
1359 				if (st->flags & ST_FIXEDBLOCKS)
1360 					st->blkno +=
1361 					    (bp->b_bcount / st->blksize);
1362 				else
1363 					st->blkno++;
1364 			}
1365 		}
1366 
1367 		biodone(bp);
1368 	}
1369 }
1370 
1371 static int
1372 stread(dev_t dev, struct uio *uio, int iomode)
1373 {
1374 	struct st_softc *st = st_cd.cd_devs[STUNIT(dev)];
1375 
1376 	return (physio(ststrategy, NULL, dev, B_READ,
1377 	    st->sc_periph->periph_channel->chan_adapter->adapt_minphys, uio));
1378 }
1379 
1380 static int
1381 stwrite(dev_t dev, struct uio *uio, int iomode)
1382 {
1383 	struct st_softc *st = st_cd.cd_devs[STUNIT(dev)];
1384 
1385 	return (physio(ststrategy, NULL, dev, B_WRITE,
1386 	    st->sc_periph->periph_channel->chan_adapter->adapt_minphys, uio));
1387 }
1388 
1389 /*
1390  * Perform special action on behalf of the user;
1391  * knows about the internals of this device
1392  */
1393 static int
1394 stioctl(dev_t dev, u_long cmd, caddr_t arg, int flag, struct lwp *l)
1395 {
1396 	int error = 0;
1397 	int unit;
1398 	int number, nmarks, dsty;
1399 	int flags;
1400 	struct st_softc *st;
1401 	int hold_blksize;
1402 	u_int8_t hold_density;
1403 	struct mtop *mt = (struct mtop *) arg;
1404 
1405 	/*
1406 	 * Find the device that the user is talking about
1407 	 */
1408 	flags = 0;		/* give error messages, act on errors etc. */
1409 	unit = STUNIT(dev);
1410 	dsty = STDSTY(dev);
1411 	st = st_cd.cd_devs[unit];
1412 	hold_blksize = st->blksize;
1413 	hold_density = st->density;
1414 
1415 	switch ((u_int) cmd) {
1416 
1417 	case MTIOCGET: {
1418 		struct mtget *g = (struct mtget *) arg;
1419 		/*
1420 		 * (to get the current state of READONLY)
1421 		 */
1422 		error = st->ops(st, ST_OPS_MODESENSE, XS_CTL_SILENT);
1423 		if (error) {
1424 			/*
1425 			 * Ignore the error if in control mode;
1426 			 * this is mandated by st(4).
1427 			 */
1428 			if (STMODE(dev) != CTRL_MODE)
1429 				break;
1430 			error = 0;
1431 		}
1432 		SC_DEBUG(st->sc_periph, SCSIPI_DB1, ("[ioctl: get status]\n"));
1433 		memset(g, 0, sizeof(struct mtget));
1434 		g->mt_type = 0x7;	/* Ultrix compat *//*? */
1435 		g->mt_blksiz = st->blksize;
1436 		g->mt_density = st->density;
1437 		g->mt_mblksiz[0] = st->modes[0].blksize;
1438 		g->mt_mblksiz[1] = st->modes[1].blksize;
1439 		g->mt_mblksiz[2] = st->modes[2].blksize;
1440 		g->mt_mblksiz[3] = st->modes[3].blksize;
1441 		g->mt_mdensity[0] = st->modes[0].density;
1442 		g->mt_mdensity[1] = st->modes[1].density;
1443 		g->mt_mdensity[2] = st->modes[2].density;
1444 		g->mt_mdensity[3] = st->modes[3].density;
1445 		g->mt_fileno = st->fileno;
1446 		g->mt_blkno = st->blkno;
1447 		if (st->flags & ST_READONLY)
1448 			g->mt_dsreg |= MT_DS_RDONLY;
1449 		if (st->flags & ST_MOUNTED)
1450 			g->mt_dsreg |= MT_DS_MOUNTED;
1451 		g->mt_resid = st->mt_resid;
1452 		g->mt_erreg = st->mt_erreg;
1453 		/*
1454 		 * clear latched errors.
1455 		 */
1456 		st->mt_resid = 0;
1457 		st->mt_erreg = 0;
1458 		st->asc = 0;
1459 		st->ascq = 0;
1460 		break;
1461 	}
1462 	case MTIOCTOP: {
1463 
1464 		SC_DEBUG(st->sc_periph, SCSIPI_DB1,
1465 		    ("[ioctl: op=0x%x count=0x%x]\n", mt->mt_op,
1466 			mt->mt_count));
1467 
1468 		/* compat: in U*x it is a short */
1469 		number = mt->mt_count;
1470 		switch ((short) (mt->mt_op)) {
1471 		case MTWEOF:	/* write an end-of-file record */
1472 			error = st_write_filemarks(st, number, flags);
1473 			break;
1474 		case MTBSF:	/* backward space file */
1475 			number = -number;
1476 		case MTFSF:	/* forward space file */
1477 			error = st_check_eod(st, FALSE, &nmarks, flags);
1478 			if (!error)
1479 				error = st_space(st, number - nmarks,
1480 				    SP_FILEMARKS, flags);
1481 			break;
1482 		case MTBSR:	/* backward space record */
1483 			number = -number;
1484 		case MTFSR:	/* forward space record */
1485 			error = st_check_eod(st, TRUE, &nmarks, flags);
1486 			if (!error)
1487 				error = st_space(st, number, SP_BLKS, flags);
1488 			break;
1489 		case MTREW:	/* rewind */
1490 			error = st_rewind(st, 0, flags);
1491 			break;
1492 		case MTOFFL:	/* rewind and put the drive offline */
1493 			st_unmount(st, EJECT);
1494 			break;
1495 		case MTNOP:	/* no operation, sets status only */
1496 			break;
1497 		case MTRETEN:	/* retension the tape */
1498 			error = st_load(st, LD_RETENSION, flags);
1499 			if (!error)
1500 				error = st_load(st, LD_LOAD, flags);
1501 			break;
1502 		case MTEOM:	/* forward space to end of media */
1503 			error = st_check_eod(st, FALSE, &nmarks, flags);
1504 			if (!error)
1505 				error = st_space(st, 1, SP_EOM, flags);
1506 			break;
1507 		case MTCACHE:	/* enable controller cache */
1508 			st->flags &= ~ST_DONTBUFFER;
1509 			goto try_new_value;
1510 		case MTNOCACHE:	/* disable controller cache */
1511 			st->flags |= ST_DONTBUFFER;
1512 			goto try_new_value;
1513 		case MTERASE:	/* erase volume */
1514 			error = st_erase(st, number, flags);
1515 			break;
1516 		case MTSETBSIZ:	/* Set block size for device */
1517 #ifdef	NOTYET
1518 			if (!(st->flags & ST_NEW_MOUNT)) {
1519 				uprintf("re-mount tape before changing blocksize");
1520 				error = EINVAL;
1521 				break;
1522 			}
1523 #endif
1524 			if (number == 0)
1525 				st->flags &= ~ST_FIXEDBLOCKS;
1526 			else {
1527 				if ((st->blkmin || st->blkmax) &&
1528 				    (number < st->blkmin ||
1529 				    number > st->blkmax)) {
1530 					error = EINVAL;
1531 					break;
1532 				}
1533 				st->flags |= ST_FIXEDBLOCKS;
1534 			}
1535 			st->blksize = number;
1536 			st->flags |= ST_BLOCK_SET;	/*XXX */
1537 			goto try_new_value;
1538 
1539 		case MTSETDNSTY:	/* Set density for device and mode */
1540 			/*
1541 			 * Any number >= 0 and <= 0xff is legal. Numbers
1542 			 * above 0x80 are 'vendor unique'.
1543 			 */
1544 			if (number < 0 || number > 255) {
1545 				error = EINVAL;
1546 				break;
1547 			} else
1548 				st->density = number;
1549 			goto try_new_value;
1550 
1551 		case MTCMPRESS:
1552 			error = st->ops(st, (number == 0) ?
1553 			    ST_OPS_CMPRSS_OFF : ST_OPS_CMPRSS_ON,
1554 			    XS_CTL_SILENT);
1555 			break;
1556 
1557 		case MTEWARN:
1558 			if (number)
1559 				st->flags |= ST_EARLYWARN;
1560 			else
1561 				st->flags &= ~ST_EARLYWARN;
1562 			break;
1563 
1564 		default:
1565 			error = EINVAL;
1566 		}
1567 		break;
1568 	}
1569 	case MTIOCIEOT:
1570 	case MTIOCEEOT:
1571 		break;
1572 
1573 	case MTIOCRDSPOS:
1574 		error = st_rdpos(st, 0, (u_int32_t *) arg);
1575 		break;
1576 
1577 	case MTIOCRDHPOS:
1578 		error = st_rdpos(st, 1, (u_int32_t *) arg);
1579 		break;
1580 
1581 	case MTIOCSLOCATE:
1582 		error = st_setpos(st, 0, (u_int32_t *) arg);
1583 		break;
1584 
1585 	case MTIOCHLOCATE:
1586 		error = st_setpos(st, 1, (u_int32_t *) arg);
1587 		break;
1588 
1589 
1590 	default:
1591 		error = scsipi_do_ioctl(st->sc_periph, dev, cmd, arg,
1592 					flag, l);
1593 		break;
1594 	}
1595 	return (error);
1596 /*-----------------------------*/
1597 try_new_value:
1598 	/*
1599 	 * Check that the mode being asked for is aggreeable to the
1600 	 * drive. If not, put it back the way it was.
1601 	 *
1602 	 * If in control mode, we can make (persistent) mode changes
1603 	 * even if no medium is loaded (see st(4)).
1604 	 */
1605 	if ((STMODE(dev) != CTRL_MODE || (st->flags & ST_MOUNTED) != 0) &&
1606 	    (error = st->ops(st, ST_OPS_MODESELECT, 0)) != 0) {
1607 		/* put it back as it was */
1608 		printf("%s: cannot set selected mode\n", st->sc_dev.dv_xname);
1609 		st->density = hold_density;
1610 		st->blksize = hold_blksize;
1611 		if (st->blksize)
1612 			st->flags |= ST_FIXEDBLOCKS;
1613 		else
1614 			st->flags &= ~ST_FIXEDBLOCKS;
1615 		return (error);
1616 	}
1617 	/*
1618 	 * As the drive liked it, if we are setting a new default,
1619 	 * set it into the structures as such.
1620 	 *
1621 	 * The means for deciding this are not finalised yet- but
1622 	 * if the device was opened in Control Mode, the values
1623 	 * are persistent now across mounts.
1624 	 */
1625 	if (STMODE(dev) == CTRL_MODE) {
1626 		switch ((short) (mt->mt_op)) {
1627 		case MTSETBSIZ:
1628 			st->modes[dsty].blksize = st->blksize;
1629 			st->modeflags[dsty] |= BLKSIZE_SET_BY_USER;
1630 			break;
1631 		case MTSETDNSTY:
1632 			st->modes[dsty].density = st->density;
1633 			st->modeflags[dsty] |= DENSITY_SET_BY_USER;
1634 			break;
1635 		}
1636 	}
1637 	return (0);
1638 }
1639 
1640 /*
1641  * Do a synchronous read.
1642  */
1643 static int
1644 st_read(struct st_softc *st, char *bf, int size, int flags)
1645 {
1646 	struct scsi_rw_tape cmd;
1647 
1648 	/*
1649 	 * If it's a null transfer, return immediatly
1650 	 */
1651 	if (size == 0)
1652 		return (0);
1653 	memset(&cmd, 0, sizeof(cmd));
1654 	cmd.opcode = READ;
1655 	if (st->flags & ST_FIXEDBLOCKS) {
1656 		cmd.byte2 |= SRW_FIXED;
1657 		_lto3b(size / (st->blksize ? st->blksize : DEF_FIXED_BSIZE),
1658 		    cmd.len);
1659 	} else
1660 		_lto3b(size, cmd.len);
1661 	return (scsipi_command(st->sc_periph,
1662 	    (void *)&cmd, sizeof(cmd), (void *)bf, size, 0, ST_IO_TIME, NULL,
1663 	    flags | XS_CTL_DATA_IN));
1664 }
1665 
1666 /*
1667  * issue an erase command
1668  */
1669 static int
1670 st_erase(struct st_softc *st, int full, int flags)
1671 {
1672 	int tmo;
1673 	struct scsi_erase cmd;
1674 
1675 	/*
1676 	 * Full erase means set LONG bit in erase command, which asks
1677 	 * the drive to erase the entire unit.  Without this bit, we're
1678 	 * asking the drive to write an erase gap.
1679 	 */
1680 	memset(&cmd, 0, sizeof(cmd));
1681 	cmd.opcode = ERASE;
1682 	if (full) {
1683 		cmd.byte2 = SE_LONG;
1684 		tmo = ST_SPC_TIME;
1685 	} else {
1686 		tmo = ST_IO_TIME;
1687 	}
1688 
1689 	/*
1690 	 * XXX We always do this asynchronously, for now, unless the device
1691 	 * has the ST_Q_ERASE_NOIMM quirk.  How long should we wait if we
1692 	 * want to (eventually) to it synchronously?
1693 	 */
1694 	if ((st->quirks & ST_Q_ERASE_NOIMM) == 0)
1695 		cmd.byte2 |= SE_IMMED;
1696 
1697 	return (scsipi_command(st->sc_periph, (void *)&cmd, sizeof(cmd), 0, 0,
1698 	    ST_RETRIES, tmo, NULL, flags));
1699 }
1700 
1701 /*
1702  * skip N blocks/filemarks/seq filemarks/eom
1703  */
1704 static int
1705 st_space(struct st_softc *st, int number, u_int what, int flags)
1706 {
1707 	struct scsi_space cmd;
1708 	int error;
1709 
1710 	switch (what) {
1711 	case SP_BLKS:
1712 		if (st->flags & ST_PER_ACTION) {
1713 			if (number > 0) {
1714 				st->flags &= ~ST_PER_ACTION;
1715 				return (EIO);
1716 			} else if (number < 0) {
1717 				if (st->flags & ST_AT_FILEMARK) {
1718 					/*
1719 					 * Handling of ST_AT_FILEMARK
1720 					 * in st_space will fill in the
1721 					 * right file mark count.
1722 					 */
1723 					error = st_space(st, 0, SP_FILEMARKS,
1724 					    flags);
1725 					if (error)
1726 						return (error);
1727 				}
1728 				if (st->flags & ST_BLANK_READ) {
1729 					st->flags &= ~ST_BLANK_READ;
1730 					return (EIO);
1731 				}
1732 				st->flags &= ~(ST_EIO_PENDING|ST_EOM_PENDING);
1733 			}
1734 		}
1735 		break;
1736 	case SP_FILEMARKS:
1737 		if (st->flags & ST_EIO_PENDING) {
1738 			if (number > 0) {
1739 				/* pretend we just discovered the error */
1740 				st->flags &= ~ST_EIO_PENDING;
1741 				return (EIO);
1742 			} else if (number < 0) {
1743 				/* back away from the error */
1744 				st->flags &= ~ST_EIO_PENDING;
1745 			}
1746 		}
1747 		if (st->flags & ST_AT_FILEMARK) {
1748 			st->flags &= ~ST_AT_FILEMARK;
1749 			number--;
1750 		}
1751 		if ((st->flags & ST_BLANK_READ) && (number < 0)) {
1752 			/* back away from unwritten tape */
1753 			st->flags &= ~ST_BLANK_READ;
1754 			number++;	/* XXX dubious */
1755 		}
1756 		break;
1757 	case SP_EOM:
1758 		if (st->flags & ST_EOM_PENDING) {
1759 			/* we're already there */
1760 			st->flags &= ~ST_EOM_PENDING;
1761 			return (0);
1762 		}
1763 		if (st->flags & ST_EIO_PENDING) {
1764 			/* pretend we just discovered the error */
1765 			st->flags &= ~ST_EIO_PENDING;
1766 			return (EIO);
1767 		}
1768 		if (st->flags & ST_AT_FILEMARK)
1769 			st->flags &= ~ST_AT_FILEMARK;
1770 		break;
1771 	}
1772 	if (number == 0)
1773 		return (0);
1774 
1775 	memset(&cmd, 0, sizeof(cmd));
1776 	cmd.opcode = SPACE;
1777 	cmd.byte2 = what;
1778 	_lto3b(number, cmd.number);
1779 
1780 	st->flags &= ~ST_POSUPDATED;
1781 	st->last_ctl_resid = 0;
1782 	error = scsipi_command(st->sc_periph, (void *)&cmd, sizeof(cmd), 0, 0,
1783 	    0, ST_SPC_TIME, NULL, flags);
1784 
1785 	if (error == 0 && (st->flags & ST_POSUPDATED) == 0) {
1786 		number = number - st->last_ctl_resid;
1787 		if (what == SP_BLKS) {
1788 			if (st->blkno != -1) {
1789 				st->blkno += number;
1790 			}
1791 		} else if (what == SP_FILEMARKS) {
1792 			if (st->fileno != -1) {
1793 				st->fileno += number;
1794 				if (number > 0) {
1795 					st->blkno = 0;
1796 				} else if (number < 0) {
1797 					st->blkno = -1;
1798 				}
1799 			}
1800 		} else if (what == SP_EOM) {
1801 			/*
1802 			 * This loses us relative position.
1803 			 */
1804 			st->fileno = st->blkno = -1;
1805 		}
1806 	}
1807 	return (error);
1808 }
1809 
1810 /*
1811  * write N filemarks
1812  */
1813 static int
1814 st_write_filemarks(struct st_softc *st, int number, int flags)
1815 {
1816 	int error;
1817 	struct scsi_write_filemarks cmd;
1818 
1819 	/*
1820 	 * It's hard to write a negative number of file marks.
1821 	 * Don't try.
1822 	 */
1823 	if (number < 0)
1824 		return (EINVAL);
1825 	switch (number) {
1826 	case 0:		/* really a command to sync the drive's buffers */
1827 		break;
1828 	case 1:
1829 		if (st->flags & ST_FM_WRITTEN)	/* already have one down */
1830 			st->flags &= ~ST_WRITTEN;
1831 		else
1832 			st->flags |= ST_FM_WRITTEN;
1833 		st->flags &= ~ST_PER_ACTION;
1834 		break;
1835 	default:
1836 		st->flags &= ~(ST_PER_ACTION | ST_WRITTEN);
1837 	}
1838 
1839 	memset(&cmd, 0, sizeof(cmd));
1840 	cmd.opcode = WRITE_FILEMARKS;
1841 	if (scsipi_periph_bustype(st->sc_periph) == SCSIPI_BUSTYPE_ATAPI)
1842 		cmd.byte2 = SR_IMMED;
1843 	/*
1844 	 * The ATAPI Onstream DI-30 doesn't support writing filemarks, but
1845 	 * WRITE_FILEMARKS is still used to flush the buffer
1846 	 */
1847 	if ((st->quirks & ST_Q_NOFILEMARKS) == 0)
1848 		_lto3b(number, cmd.number);
1849 
1850 	/* XXX WE NEED TO BE ABLE TO GET A RESIDIUAL XXX */
1851 	error = scsipi_command(st->sc_periph, (void *)&cmd, sizeof(cmd), 0, 0,
1852 	    0, ST_IO_TIME * 4, NULL, flags);
1853 	if (error == 0 && st->fileno != -1) {
1854 		st->fileno += number;
1855 	}
1856 	return (error);
1857 }
1858 
1859 /*
1860  * Make sure the right number of file marks is on tape if the
1861  * tape has been written.  If the position argument is true,
1862  * leave the tape positioned where it was originally.
1863  *
1864  * nmarks returns the number of marks to skip (or, if position
1865  * true, which were skipped) to get back original position.
1866  */
1867 static int
1868 st_check_eod(struct st_softc *st, boolean position, int *nmarks, int flags)
1869 {
1870 	int error;
1871 
1872 	switch (st->flags & (ST_WRITTEN | ST_FM_WRITTEN | ST_2FM_AT_EOD)) {
1873 	default:
1874 		*nmarks = 0;
1875 		return (0);
1876 	case ST_WRITTEN:
1877 	case ST_WRITTEN | ST_FM_WRITTEN | ST_2FM_AT_EOD:
1878 		*nmarks = 1;
1879 		break;
1880 	case ST_WRITTEN | ST_2FM_AT_EOD:
1881 		*nmarks = 2;
1882 	}
1883 	error = st_write_filemarks(st, *nmarks, flags);
1884 	if (position && !error)
1885 		error = st_space(st, -*nmarks, SP_FILEMARKS, flags);
1886 	return (error);
1887 }
1888 
1889 /*
1890  * load/unload/retension
1891  */
1892 static int
1893 st_load(struct st_softc *st, u_int type, int flags)
1894 {
1895 	int error;
1896 	struct scsi_load cmd;
1897 
1898 	if (type != LD_LOAD) {
1899 		int nmarks;
1900 
1901 		error = st_check_eod(st, FALSE, &nmarks, flags);
1902 		if (error) {
1903 			printf("%s: failed to write closing filemarks at "
1904 			    "unload, errno=%d\n", st->sc_dev.dv_xname, error);
1905 			return (error);
1906 		}
1907 	}
1908 	if (st->quirks & ST_Q_IGNORE_LOADS) {
1909 		if (type == LD_LOAD) {
1910 			/*
1911 			 * If we ignore loads, at least we should try a rewind.
1912 			 */
1913 			return st_rewind(st, 0, flags);
1914 		}
1915 		/* otherwise, we should do what's asked of us */
1916 	}
1917 
1918 	memset(&cmd, 0, sizeof(cmd));
1919 	cmd.opcode = LOAD;
1920 	if (scsipi_periph_bustype(st->sc_periph) == SCSIPI_BUSTYPE_ATAPI)
1921 		cmd.byte2 = SR_IMMED;
1922 	cmd.how = type;
1923 
1924 	error = scsipi_command(st->sc_periph, (void *)&cmd, sizeof(cmd), 0, 0,
1925 	    ST_RETRIES, ST_SPC_TIME, NULL, flags);
1926 	if (error) {
1927 		printf("%s: error %d in st_load (op %d)\n",
1928 		    st->sc_dev.dv_xname, error, type);
1929 	}
1930 	return (error);
1931 }
1932 
1933 /*
1934  *  Rewind the device
1935  */
1936 static int
1937 st_rewind(struct st_softc *st, u_int immediate, int flags)
1938 {
1939 	struct scsi_rewind cmd;
1940 	int error;
1941 	int nmarks;
1942 
1943 	error = st_check_eod(st, FALSE, &nmarks, flags);
1944 	if (error) {
1945 		printf("%s: failed to write closing filemarks at "
1946 		    "rewind, errno=%d\n", st->sc_dev.dv_xname, error);
1947 		return (error);
1948 	}
1949 	st->flags &= ~ST_PER_ACTION;
1950 
1951 	/*
1952 	 * ATAPI tapes always need immediate to be set
1953 	 */
1954 	if (scsipi_periph_bustype(st->sc_periph) == SCSIPI_BUSTYPE_ATAPI)
1955 		immediate = SR_IMMED;
1956 
1957 	memset(&cmd, 0, sizeof(cmd));
1958 	cmd.opcode = REWIND;
1959 	cmd.byte2 = immediate;
1960 
1961 	error = scsipi_command(st->sc_periph, (void *)&cmd, sizeof(cmd), 0, 0,
1962 	    ST_RETRIES, immediate ? ST_CTL_TIME: ST_SPC_TIME, NULL, flags);
1963 	if (error) {
1964 		printf("%s: error %d trying to rewind\n",
1965 		    st->sc_dev.dv_xname, error);
1966 		/* lost position */
1967 		st->fileno = st->blkno = -1;
1968 	} else {
1969 		st->fileno = st->blkno = 0;
1970 	}
1971 	return (error);
1972 }
1973 
1974 static int
1975 st_rdpos(struct st_softc *st, int hard, u_int32_t *blkptr)
1976 {
1977 	int error;
1978 	u_int8_t posdata[20];
1979 	struct scsi_tape_read_position cmd;
1980 
1981 	/*
1982 	 * We try and flush any buffered writes here if we were writing
1983 	 * and we're trying to get hardware block position. It eats
1984 	 * up performance substantially, but I'm wary of drive firmware.
1985 	 *
1986 	 * I think that *logical* block position is probably okay-
1987 	 * but hardware block position might have to wait for data
1988 	 * to hit media to be valid. Caveat Emptor.
1989 	 */
1990 
1991 	if (hard && (st->flags & ST_WRITTEN)) {
1992 		/*
1993 		 * First flush any pending writes...
1994 		 */
1995 		error = st_write_filemarks(st, 0, XS_CTL_SILENT);
1996 		/*
1997 		 * The latter case is for 'write protected' tapes
1998 		 * which are too stupid to recognize a zero count
1999 		 * for writing filemarks as a no-op.
2000 		 */
2001 		if (error != 0 && error != EACCES && error != EROFS)
2002 			return (error);
2003 	}
2004 
2005 	memset(&cmd, 0, sizeof(cmd));
2006 	memset(&posdata, 0, sizeof(posdata));
2007 	cmd.opcode = READ_POSITION;
2008 	if (hard)
2009 		cmd.byte1 = 1;
2010 
2011 	error = scsipi_command(st->sc_periph, (void *)&cmd, sizeof(cmd),
2012 	    (void *)&posdata, sizeof(posdata), ST_RETRIES, ST_CTL_TIME, NULL,
2013 	    XS_CTL_SILENT | XS_CTL_DATA_IN | XS_CTL_DATA_ONSTACK);
2014 
2015 	if (error == 0) {
2016 #if	0
2017 		printf("posdata:");
2018 		for (hard = 0; hard < sizeof(posdata); hard++)
2019 			printf("%02x ", posdata[hard] & 0xff);
2020 		printf("\n");
2021 #endif
2022 		if (posdata[0] & 0x4)	/* Block Position Unknown */
2023 			error = EINVAL;
2024 		else
2025 			*blkptr = _4btol(&posdata[4]);
2026 	}
2027 	return (error);
2028 }
2029 
2030 static int
2031 st_setpos(struct st_softc *st, int hard, u_int32_t *blkptr)
2032 {
2033 	int error;
2034 	struct scsi_tape_locate cmd;
2035 
2036 	/*
2037 	 * We used to try and flush any buffered writes here.
2038 	 * Now we push this onto user applications to either
2039 	 * flush the pending writes themselves (via a zero count
2040 	 * WRITE FILEMARKS command) or they can trust their tape
2041 	 * drive to do this correctly for them.
2042 	 *
2043 	 * There are very ugly performance limitations otherwise.
2044 	 */
2045 
2046 	memset(&cmd, 0, sizeof(cmd));
2047 	cmd.opcode = LOCATE;
2048 	if (hard)
2049 		cmd.byte2 = 1 << 2;
2050 	_lto4b(*blkptr, cmd.blkaddr);
2051 	error = scsipi_command(st->sc_periph, (void *)&cmd, sizeof(cmd), 0, 0,
2052 	    ST_RETRIES, ST_SPC_TIME, NULL, 0);
2053 	/*
2054 	 * Note file && block number position now unknown (if
2055 	 * these things ever start being maintained in this driver)
2056 	 */
2057 	st->fileno = st->blkno = -1;
2058 	return (error);
2059 }
2060 
2061 
2062 /*
2063  * Look at the returned sense and act on the error and determine
2064  * the unix error number to pass back..., 0 (== report no error),
2065  * -1 = retry the operation, -2 continue error processing.
2066  */
2067 static int
2068 st_interpret_sense(struct scsipi_xfer *xs)
2069 {
2070 	struct scsipi_periph *periph = xs->xs_periph;
2071 	struct scsi_sense_data *sense = &xs->sense.scsi_sense;
2072 	struct buf *bp = xs->bp;
2073 	struct st_softc *st = (void *)periph->periph_dev;
2074 	int retval = EJUSTRETURN;
2075 	int doprint = ((xs->xs_control & XS_CTL_SILENT) == 0);
2076 	u_int8_t key;
2077 	int32_t info;
2078 
2079 	/*
2080 	 * If it isn't a extended or extended/deferred error, let
2081 	 * the generic code handle it.
2082 	 */
2083 	if (SSD_RCODE(sense->response_code) != SSD_RCODE_CURRENT &&
2084 	    SSD_RCODE(sense->response_code) != SSD_RCODE_DEFERRED)
2085 		return (retval);
2086 
2087 	if (sense->response_code & SSD_RCODE_VALID)
2088 		info = _4btol(sense->info);
2089 	else
2090 		info = (st->flags & ST_FIXEDBLOCKS) ?
2091 		    xs->datalen / st->blksize : xs->datalen;
2092 	key = SSD_SENSE_KEY(sense->flags);
2093 	st->mt_erreg = key;
2094 	st->asc = sense->asc;
2095 	st->ascq = sense->ascq;
2096 	st->mt_resid = (short) info;
2097 
2098 	if (key == SKEY_NOT_READY && st->asc == 0x4 && st->ascq == 0x1) {
2099 		/* Not Ready, Logical Unit Is in Process Of Becoming Ready */
2100 		if (!callout_pending(&periph->periph_callout))
2101 			scsipi_periph_freeze(periph, 1);
2102 		callout_reset(&periph->periph_callout,
2103 		    hz, scsipi_periph_timed_thaw, periph);
2104 		return (ERESTART);
2105 	}
2106 
2107 	/*
2108 	 * If the device is not open yet, let generic handle
2109 	 */
2110 	if ((periph->periph_flags & PERIPH_OPEN) == 0) {
2111 		return (retval);
2112 	}
2113 
2114 	xs->resid = info;
2115 	if (st->flags & ST_FIXEDBLOCKS) {
2116 		if (bp) {
2117 			xs->resid *= st->blksize;
2118 			st->last_io_resid = xs->resid;
2119 		} else {
2120 			st->last_ctl_resid = xs->resid;
2121 		}
2122 		if (key == SKEY_VOLUME_OVERFLOW) {
2123 			st->flags |= ST_EIO_PENDING;
2124 			if (bp)
2125 				bp->b_resid = xs->resid;
2126 		} else if (sense->flags & SSD_EOM) {
2127 			if ((st->flags & ST_EARLYWARN) == 0)
2128 				st->flags |= ST_EIO_PENDING;
2129 			st->flags |= ST_EOM_PENDING;
2130 			if (bp) {
2131 #if 0
2132 				bp->b_resid = xs->resid;
2133 #else
2134 				/*
2135 				 * Grotesque as it seems, the few times
2136 				 * I've actually seen a non-zero resid,
2137 				 * the tape drive actually lied and had
2138 				 * written all the data!
2139 				 */
2140 				bp->b_resid = 0;
2141 #endif
2142 			}
2143 		}
2144 		if (sense->flags & SSD_FILEMARK) {
2145 			st->flags |= ST_AT_FILEMARK;
2146 			if (bp)
2147 				bp->b_resid = xs->resid;
2148 			if (st->fileno != (daddr_t) -1) {
2149 				st->fileno++;
2150 				st->blkno = 0;
2151 				st->flags |= ST_POSUPDATED;
2152 			}
2153 		}
2154 		if (sense->flags & SSD_ILI) {
2155 			st->flags |= ST_EIO_PENDING;
2156 			if (bp)
2157 				bp->b_resid = xs->resid;
2158 			if (sense->response_code & SSD_RCODE_VALID &&
2159 			    (xs->xs_control & XS_CTL_SILENT) == 0)
2160 				printf("%s: block wrong size, %d blocks "
2161 				    "residual\n", st->sc_dev.dv_xname, info);
2162 
2163 			/*
2164 			 * This quirk code helps the drive read
2165 			 * the first tape block, regardless of
2166 			 * format.  That is required for these
2167 			 * drives to return proper MODE SENSE
2168 			 * information.
2169 			 */
2170 			if ((st->quirks & ST_Q_SENSE_HELP) &&
2171 			    (periph->periph_flags & PERIPH_MEDIA_LOADED) == 0)
2172 				st->blksize -= 512;
2173 			else if ((st->flags & ST_POSUPDATED) == 0) {
2174 				if (st->blkno != (daddr_t) -1) {
2175 					st->blkno +=
2176 					    (xs->datalen / st->blksize);
2177 					st->flags |= ST_POSUPDATED;
2178 				}
2179 			}
2180 		}
2181 		/*
2182 		 * If data wanted and no data was transferred, do it immediately
2183 		 */
2184 		if (xs->datalen && xs->resid >= xs->datalen) {
2185 			if (st->flags & ST_EIO_PENDING)
2186 				return (EIO);
2187 			if (st->flags & ST_AT_FILEMARK) {
2188 				if (bp)
2189 					bp->b_resid = xs->resid;
2190 				return (0);
2191 			}
2192 		}
2193 	} else {		/* must be variable mode */
2194 		if (bp) {
2195 			st->last_io_resid = xs->resid;
2196 		} else {
2197 			st->last_ctl_resid = xs->resid;
2198 		}
2199 		if (sense->flags & SSD_EOM) {
2200 			/*
2201 			 * The current semantics of this
2202 			 * driver requires EOM detection
2203 			 * to return EIO unless early
2204 			 * warning detection is enabled
2205 			 * for variable mode (this is always
2206 			 * on for fixed block mode).
2207 			 */
2208 			if (st->flags & ST_EARLYWARN) {
2209 				st->flags |= ST_EOM_PENDING;
2210 				retval = 0;
2211 			} else {
2212 				retval = EIO;
2213 			}
2214 
2215 			/*
2216 			 * If it's an unadorned EOM detection,
2217 			 * suppress printing an error.
2218 			 */
2219 			if (key == SKEY_NO_SENSE) {
2220 				doprint = 0;
2221 			}
2222 		} else if (sense->flags & SSD_FILEMARK) {
2223 			retval = 0;
2224 			if (st->fileno != (daddr_t) -1) {
2225 				st->fileno++;
2226 				st->blkno = 0;
2227 				st->flags |= ST_POSUPDATED;
2228 			}
2229 		} else if (sense->flags & SSD_ILI) {
2230 			if (info < 0) {
2231 				/*
2232 				 * The tape record was bigger than the read
2233 				 * we issued.
2234 				 */
2235 				if ((xs->xs_control & XS_CTL_SILENT) == 0) {
2236 					printf("%s: %d-byte tape record too big"
2237 					    " for %d-byte user buffer\n",
2238 					    st->sc_dev.dv_xname,
2239 					    xs->datalen - info, xs->datalen);
2240 				}
2241 				retval = EIO;
2242 			} else {
2243 				retval = 0;
2244 				if (st->blkno != (daddr_t) -1) {
2245 					st->blkno++;
2246 					st->flags |= ST_POSUPDATED;
2247 				}
2248 			}
2249 		}
2250 		if (bp)
2251 			bp->b_resid = info;
2252 	}
2253 
2254 #ifndef SCSIPI_DEBUG
2255 	if (retval == 0 && key == SKEY_NO_SENSE)
2256 		doprint = 0;
2257 #endif
2258 	if (key == SKEY_BLANK_CHECK) {
2259 		/*
2260 		 * This quirk code helps the drive read the
2261 		 * first tape block, regardless of format.  That
2262 		 * is required for these drives to return proper
2263 		 * MODE SENSE information.
2264 		 */
2265 		if ((st->quirks & ST_Q_SENSE_HELP) &&
2266 		    (periph->periph_flags & PERIPH_MEDIA_LOADED) == 0) {
2267 			/* still starting */
2268 			st->blksize -= 512;
2269 		} else if (!(st->flags & (ST_2FM_AT_EOD | ST_BLANK_READ))) {
2270 			st->flags |= ST_BLANK_READ;
2271 			xs->resid = xs->datalen;
2272 			if (bp) {
2273 				bp->b_resid = xs->resid;
2274 				/* return an EOF */
2275 			}
2276 			retval = 0;
2277 			/* lost position */
2278 			st->fileno = st->blkno = -1;
2279 		}
2280 	}
2281 
2282 	/*
2283 	 * If generic sense processing will continue, we should not
2284 	 * print sense info here.
2285 	 */
2286 	if (retval == EJUSTRETURN)
2287 		doprint = 0;
2288 
2289 	if (doprint) {
2290 #ifdef	SCSIVERBOSE
2291 		scsipi_print_sense(xs, 0);
2292 #else
2293 		scsipi_printaddr(periph);
2294 		printf("Sense Key 0x%02x", key);
2295 		if ((sense->response_code & SSD_RCODE_VALID) != 0) {
2296 			switch (key) {
2297 			case SKEY_NOT_READY:
2298 			case SKEY_ILLEGAL_REQUEST:
2299 			case SKEY_UNIT_ATTENTION:
2300 			case SKEY_DATA_PROTECT:
2301 				break;
2302 			case SKEY_VOLUME_OVERFLOW:
2303 			case SKEY_BLANK_CHECK:
2304 				printf(", requested size: %d (decimal)", info);
2305 				break;
2306 			case SKEY_ABORTED_COMMAND:
2307 				if (xs->xs_retries)
2308 					printf(", retrying");
2309 				printf(", cmd 0x%x, info 0x%x",
2310 				    xs->cmd->opcode, info);
2311 				break;
2312 			default:
2313 				printf(", info = %d (decimal)", info);
2314 			}
2315 		}
2316 		if (sense->extra_len != 0) {
2317 			int n;
2318 			printf(", data =");
2319 			for (n = 0; n < sense->extra_len; n++)
2320 				printf(" %02x", sense->csi[n]);
2321 		}
2322 		printf("\n");
2323 #endif
2324 	}
2325 	return (retval);
2326 }
2327 
2328 /*
2329  * The quirk here is that the drive returns some value to st_mode_sense
2330  * incorrectly until the tape has actually passed by the head.
2331  *
2332  * The method is to set the drive to large fixed-block state (user-specified
2333  * density and 1024-byte blocks), then read and rewind to get it to sense the
2334  * tape.  If that doesn't work, try 512-byte fixed blocks.  If that doesn't
2335  * work, as a last resort, try variable- length blocks.  The result will be
2336  * the ability to do an accurate st_mode_sense.
2337  *
2338  * We know we can do a rewind because we just did a load, which implies rewind.
2339  * Rewind seems preferable to space backward if we have a virgin tape.
2340  *
2341  * The rest of the code for this quirk is in ILI processing and BLANK CHECK
2342  * error processing, both part of st_interpret_sense.
2343  */
2344 static int
2345 st_touch_tape(struct st_softc *st)
2346 {
2347 	char *bf;
2348 	int readsize;
2349 	int error;
2350 
2351 	bf = malloc(1024, M_TEMP, M_NOWAIT);
2352 	if (bf == NULL)
2353 		return (ENOMEM);
2354 
2355 	if ((error = st->ops(st, ST_OPS_MODESENSE, 0)) != 0)
2356 		goto bad;
2357 
2358 	/*
2359 	 * If the block size is already known from the
2360 	 * sense data, use it. Else start probing at 1024.
2361 	 */
2362 	if (st->media_blksize > 0)
2363 		st->blksize = st->media_blksize;
2364 	else
2365 		st->blksize = 1024;
2366 
2367 	do {
2368 		switch (st->blksize) {
2369 		case 512:
2370 		case 1024:
2371 			readsize = st->blksize;
2372 			st->flags |= ST_FIXEDBLOCKS;
2373 			break;
2374 		default:
2375 			readsize = 1;
2376 			st->flags &= ~ST_FIXEDBLOCKS;
2377 		}
2378 		if ((error = st->ops(st, ST_OPS_MODESELECT, XS_CTL_SILENT))
2379 		    != 0) {
2380 			/*
2381 			 * The device did not agree with the proposed
2382 			 * block size. If we exhausted our options,
2383 			 * return failure, else try another.
2384 			 */
2385 			if (readsize == 1)
2386 				goto bad;
2387 			st->blksize -= 512;
2388 			continue;
2389 		}
2390 		st_read(st, bf, readsize, XS_CTL_SILENT);	/* XXX */
2391 		if ((error = st_rewind(st, 0, 0)) != 0) {
2392 bad:			free(bf, M_TEMP);
2393 			return (error);
2394 		}
2395 	} while (readsize != 1 && readsize > st->blksize);
2396 
2397 	free(bf, M_TEMP);
2398 	return (0);
2399 }
2400 
2401 static int
2402 stdump(dev_t dev, daddr_t blkno, caddr_t va, size_t size)
2403 {
2404 
2405 	/* Not implemented. */
2406 	return (ENXIO);
2407 }
2408