xref: /freebsd/sys/cam/scsi/scsi_sg.c (revision 0b57cec536236d46e3dba9bd041533462f33dbb7)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3  *
4  * Copyright (c) 2007 Scott Long
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions, and the following disclaimer,
12  *    without modification, immediately at the beginning of the file.
13  * 2. The name of the author may not be used to endorse or promote products
14  *    derived from this software without specific prior written permission.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
20  * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  */
28 
29 /*
30  * scsi_sg peripheral driver.  This driver is meant to implement the Linux
31  * SG passthrough interface for SCSI.
32  */
33 
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
36 
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/kernel.h>
40 #include <sys/types.h>
41 #include <sys/bio.h>
42 #include <sys/malloc.h>
43 #include <sys/fcntl.h>
44 #include <sys/ioccom.h>
45 #include <sys/conf.h>
46 #include <sys/errno.h>
47 #include <sys/devicestat.h>
48 #include <sys/proc.h>
49 #include <sys/uio.h>
50 
51 #include <cam/cam.h>
52 #include <cam/cam_ccb.h>
53 #include <cam/cam_periph.h>
54 #include <cam/cam_queue.h>
55 #include <cam/cam_xpt_periph.h>
56 #include <cam/cam_debug.h>
57 #include <cam/cam_sim.h>
58 
59 #include <cam/scsi/scsi_all.h>
60 #include <cam/scsi/scsi_message.h>
61 #include <cam/scsi/scsi_sg.h>
62 
63 #include <compat/linux/linux_ioctl.h>
64 
65 typedef enum {
66 	SG_FLAG_LOCKED		= 0x01,
67 	SG_FLAG_INVALID		= 0x02
68 } sg_flags;
69 
70 typedef enum {
71 	SG_STATE_NORMAL
72 } sg_state;
73 
74 typedef enum {
75 	SG_RDWR_FREE,
76 	SG_RDWR_INPROG,
77 	SG_RDWR_DONE
78 } sg_rdwr_state;
79 
80 typedef enum {
81 	SG_CCB_RDWR_IO
82 } sg_ccb_types;
83 
84 #define ccb_type	ppriv_field0
85 #define ccb_rdwr	ppriv_ptr1
86 
87 struct sg_rdwr {
88 	TAILQ_ENTRY(sg_rdwr)	rdwr_link;
89 	int			tag;
90 	int			state;
91 	int			buf_len;
92 	char			*buf;
93 	union ccb		*ccb;
94 	union {
95 		struct sg_header hdr;
96 		struct sg_io_hdr io_hdr;
97 	} hdr;
98 };
99 
100 struct sg_softc {
101 	sg_state		state;
102 	sg_flags		flags;
103 	int			open_count;
104 	u_int			maxio;
105 	struct devstat		*device_stats;
106 	TAILQ_HEAD(, sg_rdwr)	rdwr_done;
107 	struct cdev		*dev;
108 	int			sg_timeout;
109 	int			sg_user_timeout;
110 	uint8_t			pd_type;
111 	union ccb		saved_ccb;
112 };
113 
114 static d_open_t		sgopen;
115 static d_close_t	sgclose;
116 static d_ioctl_t	sgioctl;
117 static d_write_t	sgwrite;
118 static d_read_t		sgread;
119 
120 static periph_init_t	sginit;
121 static periph_ctor_t	sgregister;
122 static periph_oninv_t	sgoninvalidate;
123 static periph_dtor_t	sgcleanup;
124 static void		sgasync(void *callback_arg, uint32_t code,
125 				struct cam_path *path, void *arg);
126 static void		sgdone(struct cam_periph *periph, union ccb *done_ccb);
127 static int		sgsendccb(struct cam_periph *periph, union ccb *ccb);
128 static int		sgsendrdwr(struct cam_periph *periph, union ccb *ccb);
129 static int		sgerror(union ccb *ccb, uint32_t cam_flags,
130 				uint32_t sense_flags);
131 static void		sg_scsiio_status(struct ccb_scsiio *csio,
132 					 u_short *hoststat, u_short *drvstat);
133 
134 static int		scsi_group_len(u_char cmd);
135 
136 static struct periph_driver sgdriver =
137 {
138 	sginit, "sg",
139 	TAILQ_HEAD_INITIALIZER(sgdriver.units), /* gen */ 0
140 };
141 PERIPHDRIVER_DECLARE(sg, sgdriver);
142 
143 static struct cdevsw sg_cdevsw = {
144 	.d_version =	D_VERSION,
145 	.d_flags =	D_TRACKCLOSE,
146 	.d_open =	sgopen,
147 	.d_close =	sgclose,
148 	.d_ioctl =	sgioctl,
149 	.d_write =	sgwrite,
150 	.d_read =	sgread,
151 	.d_name =	"sg",
152 };
153 
154 static int sg_version = 30125;
155 
156 static void
157 sginit(void)
158 {
159 	cam_status status;
160 
161 	/*
162 	 * Install a global async callback.  This callback will receive aync
163 	 * callbacks like "new device found".
164 	 */
165 	status = xpt_register_async(AC_FOUND_DEVICE, sgasync, NULL, NULL);
166 
167 	if (status != CAM_REQ_CMP) {
168 		printf("sg: Failed to attach master async callbac "
169 			"due to status 0x%x!\n", status);
170 	}
171 }
172 
173 static void
174 sgdevgonecb(void *arg)
175 {
176 	struct cam_periph *periph;
177 	struct sg_softc *softc;
178 	struct mtx *mtx;
179 	int i;
180 
181 	periph = (struct cam_periph *)arg;
182 	mtx = cam_periph_mtx(periph);
183 	mtx_lock(mtx);
184 
185 	softc = (struct sg_softc *)periph->softc;
186 	KASSERT(softc->open_count >= 0, ("Negative open count %d",
187 		softc->open_count));
188 
189 	/*
190 	 * When we get this callback, we will get no more close calls from
191 	 * devfs.  So if we have any dangling opens, we need to release the
192 	 * reference held for that particular context.
193 	 */
194 	for (i = 0; i < softc->open_count; i++)
195 		cam_periph_release_locked(periph);
196 
197 	softc->open_count = 0;
198 
199 	/*
200 	 * Release the reference held for the device node, it is gone now.
201 	 */
202 	cam_periph_release_locked(periph);
203 
204 	/*
205 	 * We reference the lock directly here, instead of using
206 	 * cam_periph_unlock().  The reason is that the final call to
207 	 * cam_periph_release_locked() above could result in the periph
208 	 * getting freed.  If that is the case, dereferencing the periph
209 	 * with a cam_periph_unlock() call would cause a page fault.
210 	 */
211 	mtx_unlock(mtx);
212 }
213 
214 
215 static void
216 sgoninvalidate(struct cam_periph *periph)
217 {
218 	struct sg_softc *softc;
219 
220 	softc = (struct sg_softc *)periph->softc;
221 
222 	/*
223 	 * Deregister any async callbacks.
224 	 */
225 	xpt_register_async(0, sgasync, periph, periph->path);
226 
227 	softc->flags |= SG_FLAG_INVALID;
228 
229 	/*
230 	 * Tell devfs this device has gone away, and ask for a callback
231 	 * when it has cleaned up its state.
232 	 */
233 	destroy_dev_sched_cb(softc->dev, sgdevgonecb, periph);
234 
235 	/*
236 	 * XXX Return all queued I/O with ENXIO.
237 	 * XXX Handle any transactions queued to the card
238 	 *     with XPT_ABORT_CCB.
239 	 */
240 
241 }
242 
243 static void
244 sgcleanup(struct cam_periph *periph)
245 {
246 	struct sg_softc *softc;
247 
248 	softc = (struct sg_softc *)periph->softc;
249 
250 	devstat_remove_entry(softc->device_stats);
251 
252 	free(softc, M_DEVBUF);
253 }
254 
255 static void
256 sgasync(void *callback_arg, uint32_t code, struct cam_path *path, void *arg)
257 {
258 	struct cam_periph *periph;
259 
260 	periph = (struct cam_periph *)callback_arg;
261 
262 	switch (code) {
263 	case AC_FOUND_DEVICE:
264 	{
265 		struct ccb_getdev *cgd;
266 		cam_status status;
267 
268 		cgd = (struct ccb_getdev *)arg;
269 		if (cgd == NULL)
270 			break;
271 
272 		if (cgd->protocol != PROTO_SCSI)
273 			break;
274 
275 		/*
276 		 * Allocate a peripheral instance for this device and
277 		 * start the probe process.
278 		 */
279 		status = cam_periph_alloc(sgregister, sgoninvalidate,
280 					  sgcleanup, NULL, "sg",
281 					  CAM_PERIPH_BIO, path,
282 					  sgasync, AC_FOUND_DEVICE, cgd);
283 		if ((status != CAM_REQ_CMP) && (status != CAM_REQ_INPROG)) {
284 			const struct cam_status_entry *entry;
285 
286 			entry = cam_fetch_status_entry(status);
287 			printf("sgasync: Unable to attach new device "
288 				"due to status %#x: %s\n", status, entry ?
289 				entry->status_text : "Unknown");
290 		}
291 		break;
292 	}
293 	default:
294 		cam_periph_async(periph, code, path, arg);
295 		break;
296 	}
297 }
298 
299 static cam_status
300 sgregister(struct cam_periph *periph, void *arg)
301 {
302 	struct sg_softc *softc;
303 	struct ccb_getdev *cgd;
304 	struct ccb_pathinq cpi;
305 	struct make_dev_args args;
306 	int no_tags, error;
307 
308 	cgd = (struct ccb_getdev *)arg;
309 	if (cgd == NULL) {
310 		printf("sgregister: no getdev CCB, can't register device\n");
311 		return (CAM_REQ_CMP_ERR);
312 	}
313 
314 	softc = malloc(sizeof(*softc), M_DEVBUF, M_ZERO | M_NOWAIT);
315 	if (softc == NULL) {
316 		printf("sgregister: Unable to allocate softc\n");
317 		return (CAM_REQ_CMP_ERR);
318 	}
319 
320 	softc->state = SG_STATE_NORMAL;
321 	softc->pd_type = SID_TYPE(&cgd->inq_data);
322 	softc->sg_timeout = SG_DEFAULT_TIMEOUT / SG_DEFAULT_HZ * hz;
323 	softc->sg_user_timeout = SG_DEFAULT_TIMEOUT;
324 	TAILQ_INIT(&softc->rdwr_done);
325 	periph->softc = softc;
326 
327 	xpt_path_inq(&cpi, periph->path);
328 
329 	if (cpi.maxio == 0)
330 		softc->maxio = DFLTPHYS;	/* traditional default */
331 	else if (cpi.maxio > MAXPHYS)
332 		softc->maxio = MAXPHYS;		/* for safety */
333 	else
334 		softc->maxio = cpi.maxio;	/* real value */
335 
336 	/*
337 	 * We pass in 0 for all blocksize, since we don't know what the
338 	 * blocksize of the device is, if it even has a blocksize.
339 	 */
340 	cam_periph_unlock(periph);
341 	no_tags = (cgd->inq_data.flags & SID_CmdQue) == 0;
342 	softc->device_stats = devstat_new_entry("sg",
343 			periph->unit_number, 0,
344 			DEVSTAT_NO_BLOCKSIZE
345 			| (no_tags ? DEVSTAT_NO_ORDERED_TAGS : 0),
346 			softc->pd_type |
347 			XPORT_DEVSTAT_TYPE(cpi.transport) |
348 			DEVSTAT_TYPE_PASS,
349 			DEVSTAT_PRIORITY_PASS);
350 
351 	/*
352 	 * Acquire a reference to the periph before we create the devfs
353 	 * instance for it.  We'll release this reference once the devfs
354 	 * instance has been freed.
355 	 */
356 	if (cam_periph_acquire(periph) != 0) {
357 		xpt_print(periph->path, "%s: lost periph during "
358 			  "registration!\n", __func__);
359 		cam_periph_lock(periph);
360 		return (CAM_REQ_CMP_ERR);
361 	}
362 
363 	/* Register the device */
364 	make_dev_args_init(&args);
365 	args.mda_devsw = &sg_cdevsw;
366 	args.mda_unit = periph->unit_number;
367 	args.mda_uid = UID_ROOT;
368 	args.mda_gid = GID_OPERATOR;
369 	args.mda_mode = 0600;
370 	args.mda_si_drv1 = periph;
371 	error = make_dev_s(&args, &softc->dev, "%s%d",
372 	    periph->periph_name, periph->unit_number);
373 	if (error != 0) {
374 		cam_periph_lock(periph);
375 		cam_periph_release_locked(periph);
376 		return (CAM_REQ_CMP_ERR);
377 	}
378 	if (periph->unit_number < 26) {
379 		(void)make_dev_alias(softc->dev, "sg%c",
380 		    periph->unit_number + 'a');
381 	} else {
382 		(void)make_dev_alias(softc->dev, "sg%c%c",
383 		    ((periph->unit_number / 26) - 1) + 'a',
384 		    (periph->unit_number % 26) + 'a');
385 	}
386 	cam_periph_lock(periph);
387 
388 	/*
389 	 * Add as async callback so that we get
390 	 * notified if this device goes away.
391 	 */
392 	xpt_register_async(AC_LOST_DEVICE, sgasync, periph, periph->path);
393 
394 	if (bootverbose)
395 		xpt_announce_periph(periph, NULL);
396 
397 	return (CAM_REQ_CMP);
398 }
399 
400 static void
401 sgdone(struct cam_periph *periph, union ccb *done_ccb)
402 {
403 	struct sg_softc *softc;
404 	struct ccb_scsiio *csio;
405 
406 	softc = (struct sg_softc *)periph->softc;
407 	csio = &done_ccb->csio;
408 	switch (csio->ccb_h.ccb_type) {
409 	case SG_CCB_RDWR_IO:
410 	{
411 		struct sg_rdwr *rdwr;
412 		int state;
413 
414 		devstat_end_transaction(softc->device_stats,
415 					csio->dxfer_len,
416 					csio->tag_action & 0xf,
417 					((csio->ccb_h.flags & CAM_DIR_MASK) ==
418 					CAM_DIR_NONE) ? DEVSTAT_NO_DATA :
419 					(csio->ccb_h.flags & CAM_DIR_OUT) ?
420 					DEVSTAT_WRITE : DEVSTAT_READ,
421 					NULL, NULL);
422 
423 		rdwr = done_ccb->ccb_h.ccb_rdwr;
424 		state = rdwr->state;
425 		rdwr->state = SG_RDWR_DONE;
426 		wakeup(rdwr);
427 		break;
428 	}
429 	default:
430 		panic("unknown sg CCB type");
431 	}
432 }
433 
434 static int
435 sgopen(struct cdev *dev, int flags, int fmt, struct thread *td)
436 {
437 	struct cam_periph *periph;
438 	struct sg_softc *softc;
439 	int error = 0;
440 
441 	periph = (struct cam_periph *)dev->si_drv1;
442 	if (cam_periph_acquire(periph) != 0)
443 		return (ENXIO);
444 
445 	/*
446 	 * Don't allow access when we're running at a high securelevel.
447 	 */
448 	error = securelevel_gt(td->td_ucred, 1);
449 	if (error) {
450 		cam_periph_release(periph);
451 		return (error);
452 	}
453 
454 	cam_periph_lock(periph);
455 
456 	softc = (struct sg_softc *)periph->softc;
457 	if (softc->flags & SG_FLAG_INVALID) {
458 		cam_periph_release_locked(periph);
459 		cam_periph_unlock(periph);
460 		return (ENXIO);
461 	}
462 
463 	softc->open_count++;
464 
465 	cam_periph_unlock(periph);
466 
467 	return (error);
468 }
469 
470 static int
471 sgclose(struct cdev *dev, int flag, int fmt, struct thread *td)
472 {
473 	struct cam_periph *periph;
474 	struct sg_softc   *softc;
475 	struct mtx *mtx;
476 
477 	periph = (struct cam_periph *)dev->si_drv1;
478 	mtx = cam_periph_mtx(periph);
479 	mtx_lock(mtx);
480 
481 	softc = periph->softc;
482 	softc->open_count--;
483 
484 	cam_periph_release_locked(periph);
485 
486 	/*
487 	 * We reference the lock directly here, instead of using
488 	 * cam_periph_unlock().  The reason is that the call to
489 	 * cam_periph_release_locked() above could result in the periph
490 	 * getting freed.  If that is the case, dereferencing the periph
491 	 * with a cam_periph_unlock() call would cause a page fault.
492 	 *
493 	 * cam_periph_release() avoids this problem using the same method,
494 	 * but we're manually acquiring and dropping the lock here to
495 	 * protect the open count and avoid another lock acquisition and
496 	 * release.
497 	 */
498 	mtx_unlock(mtx);
499 
500 	return (0);
501 }
502 
503 static int
504 sgioctl(struct cdev *dev, u_long cmd, caddr_t arg, int flag, struct thread *td)
505 {
506 	union ccb *ccb;
507 	struct ccb_scsiio *csio;
508 	struct cam_periph *periph;
509 	struct sg_softc *softc;
510 	struct sg_io_hdr *req;
511 	int dir, error;
512 
513 	periph = (struct cam_periph *)dev->si_drv1;
514 	cam_periph_lock(periph);
515 
516 	softc = (struct sg_softc *)periph->softc;
517 	error = 0;
518 
519 	switch (cmd) {
520 	case SG_GET_VERSION_NUM:
521 	{
522 		int *version = (int *)arg;
523 
524 		*version = sg_version;
525 		break;
526 	}
527 	case SG_SET_TIMEOUT:
528 	{
529 		u_int user_timeout = *(u_int *)arg;
530 
531 		softc->sg_user_timeout = user_timeout;
532 		softc->sg_timeout = user_timeout / SG_DEFAULT_HZ * hz;
533 		break;
534 	}
535 	case SG_GET_TIMEOUT:
536 		/*
537 		 * The value is returned directly to the syscall.
538 		 */
539 		td->td_retval[0] = softc->sg_user_timeout;
540 		error = 0;
541 		break;
542 	case SG_IO:
543 		req = (struct sg_io_hdr *)arg;
544 
545 		if (req->cmd_len > IOCDBLEN) {
546 			error = EINVAL;
547 			break;
548 		}
549 
550 		if (req->iovec_count != 0) {
551 			error = EOPNOTSUPP;
552 			break;
553 		}
554 
555 		ccb = cam_periph_getccb(periph, CAM_PRIORITY_NORMAL);
556 		csio = &ccb->csio;
557 
558 		error = copyin(req->cmdp, &csio->cdb_io.cdb_bytes,
559 		    req->cmd_len);
560 		if (error) {
561 			xpt_release_ccb(ccb);
562 			break;
563 		}
564 
565 		switch(req->dxfer_direction) {
566 		case SG_DXFER_TO_DEV:
567 			dir = CAM_DIR_OUT;
568 			break;
569 		case SG_DXFER_FROM_DEV:
570 			dir = CAM_DIR_IN;
571 			break;
572 		case SG_DXFER_TO_FROM_DEV:
573 			dir = CAM_DIR_IN | CAM_DIR_OUT;
574 			break;
575 		case SG_DXFER_NONE:
576 		default:
577 			dir = CAM_DIR_NONE;
578 			break;
579 		}
580 
581 		cam_fill_csio(csio,
582 			      /*retries*/1,
583 			      /*cbfcnp*/NULL,
584 			      dir|CAM_DEV_QFRZDIS,
585 			      MSG_SIMPLE_Q_TAG,
586 			      req->dxferp,
587 			      req->dxfer_len,
588 			      req->mx_sb_len,
589 			      req->cmd_len,
590 			      req->timeout);
591 
592 		error = sgsendccb(periph, ccb);
593 		if (error) {
594 			req->host_status = DID_ERROR;
595 			req->driver_status = DRIVER_INVALID;
596 			xpt_release_ccb(ccb);
597 			break;
598 		}
599 
600 		req->status = csio->scsi_status;
601 		req->masked_status = (csio->scsi_status >> 1) & 0x7f;
602 		sg_scsiio_status(csio, &req->host_status, &req->driver_status);
603 		req->resid = csio->resid;
604 		req->duration = csio->ccb_h.timeout;
605 		req->info = 0;
606 
607 		if ((csio->ccb_h.status & CAM_AUTOSNS_VALID)
608 		    && (req->sbp != NULL)) {
609 			req->sb_len_wr = req->mx_sb_len - csio->sense_resid;
610 			error = copyout(&csio->sense_data, req->sbp,
611 					req->sb_len_wr);
612 		}
613 
614 		xpt_release_ccb(ccb);
615 		break;
616 
617 	case SG_GET_RESERVED_SIZE:
618 	{
619 		int *size = (int *)arg;
620 		*size = DFLTPHYS;
621 		break;
622 	}
623 
624 	case SG_GET_SCSI_ID:
625 	{
626 		struct sg_scsi_id *id = (struct sg_scsi_id *)arg;
627 
628 		id->host_no = cam_sim_path(xpt_path_sim(periph->path));
629 		id->channel = xpt_path_path_id(periph->path);
630 		id->scsi_id = xpt_path_target_id(periph->path);
631 		id->lun = xpt_path_lun_id(periph->path);
632 		id->scsi_type = softc->pd_type;
633 		id->h_cmd_per_lun = 1;
634 		id->d_queue_depth = 1;
635 		id->unused[0] = 0;
636 		id->unused[1] = 0;
637 		break;
638 	}
639 
640 	case SG_GET_SG_TABLESIZE:
641 	{
642 		int *size = (int *)arg;
643 		*size = 0;
644 		break;
645 	}
646 
647 	case SG_EMULATED_HOST:
648 	case SG_SET_TRANSFORM:
649 	case SG_GET_TRANSFORM:
650 	case SG_GET_NUM_WAITING:
651 	case SG_SCSI_RESET:
652 	case SG_GET_REQUEST_TABLE:
653 	case SG_SET_KEEP_ORPHAN:
654 	case SG_GET_KEEP_ORPHAN:
655 	case SG_GET_ACCESS_COUNT:
656 	case SG_SET_FORCE_LOW_DMA:
657 	case SG_GET_LOW_DMA:
658 	case SG_SET_FORCE_PACK_ID:
659 	case SG_GET_PACK_ID:
660 	case SG_SET_RESERVED_SIZE:
661 	case SG_GET_COMMAND_Q:
662 	case SG_SET_COMMAND_Q:
663 	case SG_SET_DEBUG:
664 	case SG_NEXT_CMD_LEN:
665 	default:
666 #ifdef CAMDEBUG
667 		printf("sgioctl: rejecting cmd 0x%lx\n", cmd);
668 #endif
669 		error = ENODEV;
670 		break;
671 	}
672 
673 	cam_periph_unlock(periph);
674 	return (error);
675 }
676 
677 static int
678 sgwrite(struct cdev *dev, struct uio *uio, int ioflag)
679 {
680 	union ccb *ccb;
681 	struct cam_periph *periph;
682 	struct ccb_scsiio *csio;
683 	struct sg_softc *sc;
684 	struct sg_header *hdr;
685 	struct sg_rdwr *rdwr;
686 	u_char cdb_cmd;
687 	char *buf;
688 	int error = 0, cdb_len, buf_len, dir;
689 
690 	periph = dev->si_drv1;
691 	rdwr = malloc(sizeof(*rdwr), M_DEVBUF, M_WAITOK | M_ZERO);
692 	hdr = &rdwr->hdr.hdr;
693 
694 	/* Copy in the header block and sanity check it */
695 	if (uio->uio_resid < sizeof(*hdr)) {
696 		error = EINVAL;
697 		goto out_hdr;
698 	}
699 	error = uiomove(hdr, sizeof(*hdr), uio);
700 	if (error)
701 		goto out_hdr;
702 
703 	/* XXX: We don't support SG 3.x read/write API. */
704 	if (hdr->reply_len < 0) {
705 		error = ENODEV;
706 		goto out_hdr;
707 	}
708 
709 	ccb = xpt_alloc_ccb();
710 	if (ccb == NULL) {
711 		error = ENOMEM;
712 		goto out_hdr;
713 	}
714 	csio = &ccb->csio;
715 
716 	/*
717 	 * Copy in the CDB block.  The designers of the interface didn't
718 	 * bother to provide a size for this in the header, so we have to
719 	 * figure it out ourselves.
720 	 */
721 	if (uio->uio_resid < 1)
722 		goto out_ccb;
723 	error = uiomove(&cdb_cmd, 1, uio);
724 	if (error)
725 		goto out_ccb;
726 	if (hdr->twelve_byte)
727 		cdb_len = 12;
728 	else
729 		cdb_len = scsi_group_len(cdb_cmd);
730 	/*
731 	 * We've already read the first byte of the CDB and advanced the uio
732 	 * pointer.  Just read the rest.
733 	 */
734 	csio->cdb_io.cdb_bytes[0] = cdb_cmd;
735 	error = uiomove(&csio->cdb_io.cdb_bytes[1], cdb_len - 1, uio);
736 	if (error)
737 		goto out_ccb;
738 
739 	/*
740 	 * Now set up the data block.  Again, the designers didn't bother
741 	 * to make this reliable.
742 	 */
743 	buf_len = uio->uio_resid;
744 	if (buf_len != 0) {
745 		buf = malloc(buf_len, M_DEVBUF, M_WAITOK | M_ZERO);
746 		error = uiomove(buf, buf_len, uio);
747 		if (error)
748 			goto out_buf;
749 		dir = CAM_DIR_OUT;
750 	} else if (hdr->reply_len != 0) {
751 		buf = malloc(hdr->reply_len, M_DEVBUF, M_WAITOK | M_ZERO);
752 		buf_len = hdr->reply_len;
753 		dir = CAM_DIR_IN;
754 	} else {
755 		buf = NULL;
756 		buf_len = 0;
757 		dir = CAM_DIR_NONE;
758 	}
759 
760 	cam_periph_lock(periph);
761 	sc = periph->softc;
762 	xpt_setup_ccb(&ccb->ccb_h, periph->path, CAM_PRIORITY_NORMAL);
763 	cam_fill_csio(csio,
764 		      /*retries*/1,
765 		      sgdone,
766 		      dir|CAM_DEV_QFRZDIS,
767 		      MSG_SIMPLE_Q_TAG,
768 		      buf,
769 		      buf_len,
770 		      SG_MAX_SENSE,
771 		      cdb_len,
772 		      sc->sg_timeout);
773 
774 	/*
775 	 * Send off the command and hope that it works. This path does not
776 	 * go through sgstart because the I/O is supposed to be asynchronous.
777 	 */
778 	rdwr->buf = buf;
779 	rdwr->buf_len = buf_len;
780 	rdwr->tag = hdr->pack_id;
781 	rdwr->ccb = ccb;
782 	rdwr->state = SG_RDWR_INPROG;
783 	ccb->ccb_h.ccb_rdwr = rdwr;
784 	ccb->ccb_h.ccb_type = SG_CCB_RDWR_IO;
785 	TAILQ_INSERT_TAIL(&sc->rdwr_done, rdwr, rdwr_link);
786 	error = sgsendrdwr(periph, ccb);
787 	cam_periph_unlock(periph);
788 	return (error);
789 
790 out_buf:
791 	free(buf, M_DEVBUF);
792 out_ccb:
793 	xpt_free_ccb(ccb);
794 out_hdr:
795 	free(rdwr, M_DEVBUF);
796 	return (error);
797 }
798 
799 static int
800 sgread(struct cdev *dev, struct uio *uio, int ioflag)
801 {
802 	struct ccb_scsiio *csio;
803 	struct cam_periph *periph;
804 	struct sg_softc *sc;
805 	struct sg_header *hdr;
806 	struct sg_rdwr *rdwr;
807 	u_short hstat, dstat;
808 	int error, pack_len, reply_len, pack_id;
809 
810 	periph = dev->si_drv1;
811 
812 	/* XXX The pack len field needs to be updated and written out instead
813 	 * of discarded.  Not sure how to do that.
814 	 */
815 	uio->uio_rw = UIO_WRITE;
816 	if ((error = uiomove(&pack_len, 4, uio)) != 0)
817 		return (error);
818 	if ((error = uiomove(&reply_len, 4, uio)) != 0)
819 		return (error);
820 	if ((error = uiomove(&pack_id, 4, uio)) != 0)
821 		return (error);
822 	uio->uio_rw = UIO_READ;
823 
824 	cam_periph_lock(periph);
825 	sc = periph->softc;
826 search:
827 	TAILQ_FOREACH(rdwr, &sc->rdwr_done, rdwr_link) {
828 		if (rdwr->tag == pack_id)
829 			break;
830 	}
831 	if ((rdwr == NULL) || (rdwr->state != SG_RDWR_DONE)) {
832 		if (cam_periph_sleep(periph, rdwr, PCATCH, "sgread", 0) == ERESTART)
833 			return (EAGAIN);
834 		goto search;
835 	}
836 	TAILQ_REMOVE(&sc->rdwr_done, rdwr, rdwr_link);
837 	cam_periph_unlock(periph);
838 
839 	hdr = &rdwr->hdr.hdr;
840 	csio = &rdwr->ccb->csio;
841 	sg_scsiio_status(csio, &hstat, &dstat);
842 	hdr->host_status = hstat;
843 	hdr->driver_status = dstat;
844 	hdr->target_status = csio->scsi_status >> 1;
845 
846 	switch (hstat) {
847 	case DID_OK:
848 	case DID_PASSTHROUGH:
849 	case DID_SOFT_ERROR:
850 		hdr->result = 0;
851 		break;
852 	case DID_NO_CONNECT:
853 	case DID_BUS_BUSY:
854 	case DID_TIME_OUT:
855 		hdr->result = EBUSY;
856 		break;
857 	case DID_BAD_TARGET:
858 	case DID_ABORT:
859 	case DID_PARITY:
860 	case DID_RESET:
861 	case DID_BAD_INTR:
862 	case DID_ERROR:
863 	default:
864 		hdr->result = EIO;
865 		break;
866 	}
867 
868 	if (dstat == DRIVER_SENSE) {
869 		bcopy(&csio->sense_data, hdr->sense_buffer,
870 		      min(csio->sense_len, SG_MAX_SENSE));
871 #ifdef CAMDEBUG
872 		scsi_sense_print(csio);
873 #endif
874 	}
875 
876 	error = uiomove(&hdr->result, sizeof(*hdr) -
877 			offsetof(struct sg_header, result), uio);
878 	if ((error == 0) && (hdr->result == 0))
879 		error = uiomove(rdwr->buf, rdwr->buf_len, uio);
880 
881 	cam_periph_lock(periph);
882 	xpt_free_ccb(rdwr->ccb);
883 	cam_periph_unlock(periph);
884 	free(rdwr->buf, M_DEVBUF);
885 	free(rdwr, M_DEVBUF);
886 	return (error);
887 }
888 
889 static int
890 sgsendccb(struct cam_periph *periph, union ccb *ccb)
891 {
892 	struct sg_softc *softc;
893 	struct cam_periph_map_info mapinfo;
894 	int error;
895 
896 	softc = periph->softc;
897 	bzero(&mapinfo, sizeof(mapinfo));
898 
899 	/*
900 	 * cam_periph_mapmem calls into proc and vm functions that can
901 	 * sleep as well as trigger I/O, so we can't hold the lock.
902 	 * Dropping it here is reasonably safe.
903 	 * The only CCB opcode that is possible here is XPT_SCSI_IO, no
904 	 * need for additional checks.
905 	 */
906 	cam_periph_unlock(periph);
907 	error = cam_periph_mapmem(ccb, &mapinfo, softc->maxio);
908 	cam_periph_lock(periph);
909 	if (error)
910 		return (error);
911 
912 	error = cam_periph_runccb(ccb,
913 				  sgerror,
914 				  CAM_RETRY_SELTO,
915 				  SF_RETRY_UA,
916 				  softc->device_stats);
917 
918 	cam_periph_unlock(periph);
919 	cam_periph_unmapmem(ccb, &mapinfo);
920 	cam_periph_lock(periph);
921 
922 	return (error);
923 }
924 
925 static int
926 sgsendrdwr(struct cam_periph *periph, union ccb *ccb)
927 {
928 	struct sg_softc *softc;
929 
930 	softc = periph->softc;
931 	devstat_start_transaction(softc->device_stats, NULL);
932 	xpt_action(ccb);
933 	return (0);
934 }
935 
936 static int
937 sgerror(union ccb *ccb, uint32_t cam_flags, uint32_t sense_flags)
938 {
939 	struct cam_periph *periph;
940 	struct sg_softc *softc;
941 
942 	periph = xpt_path_periph(ccb->ccb_h.path);
943 	softc = (struct sg_softc *)periph->softc;
944 
945 	return (cam_periph_error(ccb, cam_flags, sense_flags));
946 }
947 
948 static void
949 sg_scsiio_status(struct ccb_scsiio *csio, u_short *hoststat, u_short *drvstat)
950 {
951 	int status;
952 
953 	status = csio->ccb_h.status;
954 
955 	switch (status & CAM_STATUS_MASK) {
956 	case CAM_REQ_CMP:
957 		*hoststat = DID_OK;
958 		*drvstat = 0;
959 		break;
960 	case CAM_REQ_CMP_ERR:
961 		*hoststat = DID_ERROR;
962 		*drvstat = 0;
963 		break;
964 	case CAM_REQ_ABORTED:
965 		*hoststat = DID_ABORT;
966 		*drvstat = 0;
967 		break;
968 	case CAM_REQ_INVALID:
969 		*hoststat = DID_ERROR;
970 		*drvstat = DRIVER_INVALID;
971 		break;
972 	case CAM_DEV_NOT_THERE:
973 		*hoststat = DID_BAD_TARGET;
974 		*drvstat = 0;
975 		break;
976 	case CAM_SEL_TIMEOUT:
977 		*hoststat = DID_NO_CONNECT;
978 		*drvstat = 0;
979 		break;
980 	case CAM_CMD_TIMEOUT:
981 		*hoststat = DID_TIME_OUT;
982 		*drvstat = 0;
983 		break;
984 	case CAM_SCSI_STATUS_ERROR:
985 		*hoststat = DID_ERROR;
986 		*drvstat = 0;
987 		break;
988 	case CAM_SCSI_BUS_RESET:
989 		*hoststat = DID_RESET;
990 		*drvstat = 0;
991 		break;
992 	case CAM_UNCOR_PARITY:
993 		*hoststat = DID_PARITY;
994 		*drvstat = 0;
995 		break;
996 	case CAM_SCSI_BUSY:
997 		*hoststat = DID_BUS_BUSY;
998 		*drvstat = 0;
999 		break;
1000 	default:
1001 		*hoststat = DID_ERROR;
1002 		*drvstat = DRIVER_ERROR;
1003 	}
1004 
1005 	if (status & CAM_AUTOSNS_VALID)
1006 		*drvstat = DRIVER_SENSE;
1007 }
1008 
1009 static int
1010 scsi_group_len(u_char cmd)
1011 {
1012 	int len[] = {6, 10, 10, 12, 12, 12, 10, 10};
1013 	int group;
1014 
1015 	group = (cmd >> 5) & 0x7;
1016 	return (len[group]);
1017 }
1018 
1019