xref: /openbmc/linux/drivers/scsi/sr.c (revision 84d517f3)
1 /*
2  *  sr.c Copyright (C) 1992 David Giller
3  *           Copyright (C) 1993, 1994, 1995, 1999 Eric Youngdale
4  *
5  *  adapted from:
6  *      sd.c Copyright (C) 1992 Drew Eckhardt
7  *      Linux scsi disk driver by
8  *              Drew Eckhardt <drew@colorado.edu>
9  *
10  *	Modified by Eric Youngdale ericy@andante.org to
11  *	add scatter-gather, multiple outstanding request, and other
12  *	enhancements.
13  *
14  *      Modified by Eric Youngdale eric@andante.org to support loadable
15  *      low-level scsi drivers.
16  *
17  *      Modified by Thomas Quinot thomas@melchior.cuivre.fdn.fr to
18  *      provide auto-eject.
19  *
20  *      Modified by Gerd Knorr <kraxel@cs.tu-berlin.de> to support the
21  *      generic cdrom interface
22  *
23  *      Modified by Jens Axboe <axboe@suse.de> - Uniform sr_packet()
24  *      interface, capabilities probe additions, ioctl cleanups, etc.
25  *
26  *	Modified by Richard Gooch <rgooch@atnf.csiro.au> to support devfs
27  *
28  *	Modified by Jens Axboe <axboe@suse.de> - support DVD-RAM
29  *	transparently and lose the GHOST hack
30  *
31  *	Modified by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
32  *	check resource allocation in sr_init and some cleanups
33  */
34 
35 #include <linux/module.h>
36 #include <linux/fs.h>
37 #include <linux/kernel.h>
38 #include <linux/mm.h>
39 #include <linux/bio.h>
40 #include <linux/string.h>
41 #include <linux/errno.h>
42 #include <linux/cdrom.h>
43 #include <linux/interrupt.h>
44 #include <linux/init.h>
45 #include <linux/blkdev.h>
46 #include <linux/mutex.h>
47 #include <linux/slab.h>
48 #include <linux/pm_runtime.h>
49 #include <asm/uaccess.h>
50 
51 #include <scsi/scsi.h>
52 #include <scsi/scsi_dbg.h>
53 #include <scsi/scsi_device.h>
54 #include <scsi/scsi_driver.h>
55 #include <scsi/scsi_cmnd.h>
56 #include <scsi/scsi_eh.h>
57 #include <scsi/scsi_host.h>
58 #include <scsi/scsi_ioctl.h>	/* For the door lock/unlock commands */
59 
60 #include "scsi_logging.h"
61 #include "sr.h"
62 
63 
64 MODULE_DESCRIPTION("SCSI cdrom (sr) driver");
65 MODULE_LICENSE("GPL");
66 MODULE_ALIAS_BLOCKDEV_MAJOR(SCSI_CDROM_MAJOR);
67 MODULE_ALIAS_SCSI_DEVICE(TYPE_ROM);
68 MODULE_ALIAS_SCSI_DEVICE(TYPE_WORM);
69 
70 #define SR_DISKS	256
71 
72 #define SR_CAPABILITIES \
73 	(CDC_CLOSE_TRAY|CDC_OPEN_TRAY|CDC_LOCK|CDC_SELECT_SPEED| \
74 	 CDC_SELECT_DISC|CDC_MULTI_SESSION|CDC_MCN|CDC_MEDIA_CHANGED| \
75 	 CDC_PLAY_AUDIO|CDC_RESET|CDC_DRIVE_STATUS| \
76 	 CDC_CD_R|CDC_CD_RW|CDC_DVD|CDC_DVD_R|CDC_DVD_RAM|CDC_GENERIC_PACKET| \
77 	 CDC_MRW|CDC_MRW_W|CDC_RAM)
78 
79 static DEFINE_MUTEX(sr_mutex);
80 static int sr_probe(struct device *);
81 static int sr_remove(struct device *);
82 static int sr_done(struct scsi_cmnd *);
83 static int sr_runtime_suspend(struct device *dev);
84 
85 static struct dev_pm_ops sr_pm_ops = {
86 	.runtime_suspend	= sr_runtime_suspend,
87 };
88 
89 static struct scsi_driver sr_template = {
90 	.owner			= THIS_MODULE,
91 	.gendrv = {
92 		.name   	= "sr",
93 		.probe		= sr_probe,
94 		.remove		= sr_remove,
95 		.pm		= &sr_pm_ops,
96 	},
97 	.done			= sr_done,
98 };
99 
100 static unsigned long sr_index_bits[SR_DISKS / BITS_PER_LONG];
101 static DEFINE_SPINLOCK(sr_index_lock);
102 
103 /* This semaphore is used to mediate the 0->1 reference get in the
104  * face of object destruction (i.e. we can't allow a get on an
105  * object after last put) */
106 static DEFINE_MUTEX(sr_ref_mutex);
107 
108 static int sr_open(struct cdrom_device_info *, int);
109 static void sr_release(struct cdrom_device_info *);
110 
111 static void get_sectorsize(struct scsi_cd *);
112 static void get_capabilities(struct scsi_cd *);
113 
114 static unsigned int sr_check_events(struct cdrom_device_info *cdi,
115 				    unsigned int clearing, int slot);
116 static int sr_packet(struct cdrom_device_info *, struct packet_command *);
117 
118 static struct cdrom_device_ops sr_dops = {
119 	.open			= sr_open,
120 	.release	 	= sr_release,
121 	.drive_status	 	= sr_drive_status,
122 	.check_events		= sr_check_events,
123 	.tray_move		= sr_tray_move,
124 	.lock_door		= sr_lock_door,
125 	.select_speed		= sr_select_speed,
126 	.get_last_session	= sr_get_last_session,
127 	.get_mcn		= sr_get_mcn,
128 	.reset			= sr_reset,
129 	.audio_ioctl		= sr_audio_ioctl,
130 	.capability		= SR_CAPABILITIES,
131 	.generic_packet		= sr_packet,
132 };
133 
134 static void sr_kref_release(struct kref *kref);
135 
136 static inline struct scsi_cd *scsi_cd(struct gendisk *disk)
137 {
138 	return container_of(disk->private_data, struct scsi_cd, driver);
139 }
140 
141 static int sr_runtime_suspend(struct device *dev)
142 {
143 	struct scsi_cd *cd = dev_get_drvdata(dev);
144 
145 	if (cd->media_present)
146 		return -EBUSY;
147 	else
148 		return 0;
149 }
150 
151 /*
152  * The get and put routines for the struct scsi_cd.  Note this entity
153  * has a scsi_device pointer and owns a reference to this.
154  */
155 static inline struct scsi_cd *scsi_cd_get(struct gendisk *disk)
156 {
157 	struct scsi_cd *cd = NULL;
158 
159 	mutex_lock(&sr_ref_mutex);
160 	if (disk->private_data == NULL)
161 		goto out;
162 	cd = scsi_cd(disk);
163 	kref_get(&cd->kref);
164 	if (scsi_device_get(cd->device)) {
165 		kref_put(&cd->kref, sr_kref_release);
166 		cd = NULL;
167 	}
168  out:
169 	mutex_unlock(&sr_ref_mutex);
170 	return cd;
171 }
172 
173 static void scsi_cd_put(struct scsi_cd *cd)
174 {
175 	struct scsi_device *sdev = cd->device;
176 
177 	mutex_lock(&sr_ref_mutex);
178 	kref_put(&cd->kref, sr_kref_release);
179 	scsi_device_put(sdev);
180 	mutex_unlock(&sr_ref_mutex);
181 }
182 
183 static unsigned int sr_get_events(struct scsi_device *sdev)
184 {
185 	u8 buf[8];
186 	u8 cmd[] = { GET_EVENT_STATUS_NOTIFICATION,
187 		     1,			/* polled */
188 		     0, 0,		/* reserved */
189 		     1 << 4,		/* notification class: media */
190 		     0, 0,		/* reserved */
191 		     0, sizeof(buf),	/* allocation length */
192 		     0,			/* control */
193 	};
194 	struct event_header *eh = (void *)buf;
195 	struct media_event_desc *med = (void *)(buf + 4);
196 	struct scsi_sense_hdr sshdr;
197 	int result;
198 
199 	result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buf, sizeof(buf),
200 				  &sshdr, SR_TIMEOUT, MAX_RETRIES, NULL);
201 	if (scsi_sense_valid(&sshdr) && sshdr.sense_key == UNIT_ATTENTION)
202 		return DISK_EVENT_MEDIA_CHANGE;
203 
204 	if (result || be16_to_cpu(eh->data_len) < sizeof(*med))
205 		return 0;
206 
207 	if (eh->nea || eh->notification_class != 0x4)
208 		return 0;
209 
210 	if (med->media_event_code == 1)
211 		return DISK_EVENT_EJECT_REQUEST;
212 	else if (med->media_event_code == 2)
213 		return DISK_EVENT_MEDIA_CHANGE;
214 	return 0;
215 }
216 
217 /*
218  * This function checks to see if the media has been changed or eject
219  * button has been pressed.  It is possible that we have already
220  * sensed a change, or the drive may have sensed one and not yet
221  * reported it.  The past events are accumulated in sdev->changed and
222  * returned together with the current state.
223  */
224 static unsigned int sr_check_events(struct cdrom_device_info *cdi,
225 				    unsigned int clearing, int slot)
226 {
227 	struct scsi_cd *cd = cdi->handle;
228 	bool last_present;
229 	struct scsi_sense_hdr sshdr;
230 	unsigned int events;
231 	int ret;
232 
233 	/* no changer support */
234 	if (CDSL_CURRENT != slot)
235 		return 0;
236 
237 	events = sr_get_events(cd->device);
238 	cd->get_event_changed |= events & DISK_EVENT_MEDIA_CHANGE;
239 
240 	/*
241 	 * If earlier GET_EVENT_STATUS_NOTIFICATION and TUR did not agree
242 	 * for several times in a row.  We rely on TUR only for this likely
243 	 * broken device, to prevent generating incorrect media changed
244 	 * events for every open().
245 	 */
246 	if (cd->ignore_get_event) {
247 		events &= ~DISK_EVENT_MEDIA_CHANGE;
248 		goto do_tur;
249 	}
250 
251 	/*
252 	 * GET_EVENT_STATUS_NOTIFICATION is enough unless MEDIA_CHANGE
253 	 * is being cleared.  Note that there are devices which hang
254 	 * if asked to execute TUR repeatedly.
255 	 */
256 	if (cd->device->changed) {
257 		events |= DISK_EVENT_MEDIA_CHANGE;
258 		cd->device->changed = 0;
259 		cd->tur_changed = true;
260 	}
261 
262 	if (!(clearing & DISK_EVENT_MEDIA_CHANGE))
263 		return events;
264 do_tur:
265 	/* let's see whether the media is there with TUR */
266 	last_present = cd->media_present;
267 	ret = scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES, &sshdr);
268 
269 	/*
270 	 * Media is considered to be present if TUR succeeds or fails with
271 	 * sense data indicating something other than media-not-present
272 	 * (ASC 0x3a).
273 	 */
274 	cd->media_present = scsi_status_is_good(ret) ||
275 		(scsi_sense_valid(&sshdr) && sshdr.asc != 0x3a);
276 
277 	if (last_present != cd->media_present)
278 		cd->device->changed = 1;
279 
280 	if (cd->device->changed) {
281 		events |= DISK_EVENT_MEDIA_CHANGE;
282 		cd->device->changed = 0;
283 		cd->tur_changed = true;
284 	}
285 
286 	if (cd->ignore_get_event)
287 		return events;
288 
289 	/* check whether GET_EVENT is reporting spurious MEDIA_CHANGE */
290 	if (!cd->tur_changed) {
291 		if (cd->get_event_changed) {
292 			if (cd->tur_mismatch++ > 8) {
293 				sdev_printk(KERN_WARNING, cd->device,
294 					    "GET_EVENT and TUR disagree continuously, suppress GET_EVENT events\n");
295 				cd->ignore_get_event = true;
296 			}
297 		} else {
298 			cd->tur_mismatch = 0;
299 		}
300 	}
301 	cd->tur_changed = false;
302 	cd->get_event_changed = false;
303 
304 	return events;
305 }
306 
307 /*
308  * sr_done is the interrupt routine for the device driver.
309  *
310  * It will be notified on the end of a SCSI read / write, and will take one
311  * of several actions based on success or failure.
312  */
313 static int sr_done(struct scsi_cmnd *SCpnt)
314 {
315 	int result = SCpnt->result;
316 	int this_count = scsi_bufflen(SCpnt);
317 	int good_bytes = (result == 0 ? this_count : 0);
318 	int block_sectors = 0;
319 	long error_sector;
320 	struct scsi_cd *cd = scsi_cd(SCpnt->request->rq_disk);
321 
322 #ifdef DEBUG
323 	printk("sr.c done: %x\n", result);
324 #endif
325 
326 	/*
327 	 * Handle MEDIUM ERRORs or VOLUME OVERFLOWs that indicate partial
328 	 * success.  Since this is a relatively rare error condition, no
329 	 * care is taken to avoid unnecessary additional work such as
330 	 * memcpy's that could be avoided.
331 	 */
332 	if (driver_byte(result) != 0 &&		/* An error occurred */
333 	    (SCpnt->sense_buffer[0] & 0x7f) == 0x70) { /* Sense current */
334 		switch (SCpnt->sense_buffer[2]) {
335 		case MEDIUM_ERROR:
336 		case VOLUME_OVERFLOW:
337 		case ILLEGAL_REQUEST:
338 			if (!(SCpnt->sense_buffer[0] & 0x90))
339 				break;
340 			error_sector = (SCpnt->sense_buffer[3] << 24) |
341 				(SCpnt->sense_buffer[4] << 16) |
342 				(SCpnt->sense_buffer[5] << 8) |
343 				SCpnt->sense_buffer[6];
344 			if (SCpnt->request->bio != NULL)
345 				block_sectors =
346 					bio_sectors(SCpnt->request->bio);
347 			if (block_sectors < 4)
348 				block_sectors = 4;
349 			if (cd->device->sector_size == 2048)
350 				error_sector <<= 2;
351 			error_sector &= ~(block_sectors - 1);
352 			good_bytes = (error_sector -
353 				      blk_rq_pos(SCpnt->request)) << 9;
354 			if (good_bytes < 0 || good_bytes >= this_count)
355 				good_bytes = 0;
356 			/*
357 			 * The SCSI specification allows for the value
358 			 * returned by READ CAPACITY to be up to 75 2K
359 			 * sectors past the last readable block.
360 			 * Therefore, if we hit a medium error within the
361 			 * last 75 2K sectors, we decrease the saved size
362 			 * value.
363 			 */
364 			if (error_sector < get_capacity(cd->disk) &&
365 			    cd->capacity - error_sector < 4 * 75)
366 				set_capacity(cd->disk, error_sector);
367 			break;
368 
369 		case RECOVERED_ERROR:
370 			good_bytes = this_count;
371 			break;
372 
373 		default:
374 			break;
375 		}
376 	}
377 
378 	return good_bytes;
379 }
380 
381 static int sr_prep_fn(struct request_queue *q, struct request *rq)
382 {
383 	int block = 0, this_count, s_size;
384 	struct scsi_cd *cd;
385 	struct scsi_cmnd *SCpnt;
386 	struct scsi_device *sdp = q->queuedata;
387 	int ret;
388 
389 	if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
390 		ret = scsi_setup_blk_pc_cmnd(sdp, rq);
391 		goto out;
392 	} else if (rq->cmd_type != REQ_TYPE_FS) {
393 		ret = BLKPREP_KILL;
394 		goto out;
395 	}
396 	ret = scsi_setup_fs_cmnd(sdp, rq);
397 	if (ret != BLKPREP_OK)
398 		goto out;
399 	SCpnt = rq->special;
400 	cd = scsi_cd(rq->rq_disk);
401 
402 	/* from here on until we're complete, any goto out
403 	 * is used for a killable error condition */
404 	ret = BLKPREP_KILL;
405 
406 	SCSI_LOG_HLQUEUE(1, printk("Doing sr request, dev = %s, block = %d\n",
407 				cd->disk->disk_name, block));
408 
409 	if (!cd->device || !scsi_device_online(cd->device)) {
410 		SCSI_LOG_HLQUEUE(2, printk("Finishing %u sectors\n",
411 					   blk_rq_sectors(rq)));
412 		SCSI_LOG_HLQUEUE(2, printk("Retry with 0x%p\n", SCpnt));
413 		goto out;
414 	}
415 
416 	if (cd->device->changed) {
417 		/*
418 		 * quietly refuse to do anything to a changed disc until the
419 		 * changed bit has been reset
420 		 */
421 		goto out;
422 	}
423 
424 	/*
425 	 * we do lazy blocksize switching (when reading XA sectors,
426 	 * see CDROMREADMODE2 ioctl)
427 	 */
428 	s_size = cd->device->sector_size;
429 	if (s_size > 2048) {
430 		if (!in_interrupt())
431 			sr_set_blocklength(cd, 2048);
432 		else
433 			printk("sr: can't switch blocksize: in interrupt\n");
434 	}
435 
436 	if (s_size != 512 && s_size != 1024 && s_size != 2048) {
437 		scmd_printk(KERN_ERR, SCpnt, "bad sector size %d\n", s_size);
438 		goto out;
439 	}
440 
441 	if (rq_data_dir(rq) == WRITE) {
442 		if (!cd->device->writeable)
443 			goto out;
444 		SCpnt->cmnd[0] = WRITE_10;
445 		SCpnt->sc_data_direction = DMA_TO_DEVICE;
446  	 	cd->cdi.media_written = 1;
447 	} else if (rq_data_dir(rq) == READ) {
448 		SCpnt->cmnd[0] = READ_10;
449 		SCpnt->sc_data_direction = DMA_FROM_DEVICE;
450 	} else {
451 		blk_dump_rq_flags(rq, "Unknown sr command");
452 		goto out;
453 	}
454 
455 	{
456 		struct scatterlist *sg;
457 		int i, size = 0, sg_count = scsi_sg_count(SCpnt);
458 
459 		scsi_for_each_sg(SCpnt, sg, sg_count, i)
460 			size += sg->length;
461 
462 		if (size != scsi_bufflen(SCpnt)) {
463 			scmd_printk(KERN_ERR, SCpnt,
464 				"mismatch count %d, bytes %d\n",
465 				size, scsi_bufflen(SCpnt));
466 			if (scsi_bufflen(SCpnt) > size)
467 				SCpnt->sdb.length = size;
468 		}
469 	}
470 
471 	/*
472 	 * request doesn't start on hw block boundary, add scatter pads
473 	 */
474 	if (((unsigned int)blk_rq_pos(rq) % (s_size >> 9)) ||
475 	    (scsi_bufflen(SCpnt) % s_size)) {
476 		scmd_printk(KERN_NOTICE, SCpnt, "unaligned transfer\n");
477 		goto out;
478 	}
479 
480 	this_count = (scsi_bufflen(SCpnt) >> 9) / (s_size >> 9);
481 
482 
483 	SCSI_LOG_HLQUEUE(2, printk("%s : %s %d/%u 512 byte blocks.\n",
484 				cd->cdi.name,
485 				(rq_data_dir(rq) == WRITE) ?
486 					"writing" : "reading",
487 				this_count, blk_rq_sectors(rq)));
488 
489 	SCpnt->cmnd[1] = 0;
490 	block = (unsigned int)blk_rq_pos(rq) / (s_size >> 9);
491 
492 	if (this_count > 0xffff) {
493 		this_count = 0xffff;
494 		SCpnt->sdb.length = this_count * s_size;
495 	}
496 
497 	SCpnt->cmnd[2] = (unsigned char) (block >> 24) & 0xff;
498 	SCpnt->cmnd[3] = (unsigned char) (block >> 16) & 0xff;
499 	SCpnt->cmnd[4] = (unsigned char) (block >> 8) & 0xff;
500 	SCpnt->cmnd[5] = (unsigned char) block & 0xff;
501 	SCpnt->cmnd[6] = SCpnt->cmnd[9] = 0;
502 	SCpnt->cmnd[7] = (unsigned char) (this_count >> 8) & 0xff;
503 	SCpnt->cmnd[8] = (unsigned char) this_count & 0xff;
504 
505 	/*
506 	 * We shouldn't disconnect in the middle of a sector, so with a dumb
507 	 * host adapter, it's safe to assume that we can at least transfer
508 	 * this many bytes between each connect / disconnect.
509 	 */
510 	SCpnt->transfersize = cd->device->sector_size;
511 	SCpnt->underflow = this_count << 9;
512 	SCpnt->allowed = MAX_RETRIES;
513 
514 	/*
515 	 * This indicates that the command is ready from our end to be
516 	 * queued.
517 	 */
518 	ret = BLKPREP_OK;
519  out:
520 	return scsi_prep_return(q, rq, ret);
521 }
522 
523 static int sr_block_open(struct block_device *bdev, fmode_t mode)
524 {
525 	struct scsi_cd *cd;
526 	int ret = -ENXIO;
527 
528 	mutex_lock(&sr_mutex);
529 	cd = scsi_cd_get(bdev->bd_disk);
530 	if (cd) {
531 		ret = cdrom_open(&cd->cdi, bdev, mode);
532 		if (ret)
533 			scsi_cd_put(cd);
534 	}
535 	mutex_unlock(&sr_mutex);
536 	return ret;
537 }
538 
539 static void sr_block_release(struct gendisk *disk, fmode_t mode)
540 {
541 	struct scsi_cd *cd = scsi_cd(disk);
542 	mutex_lock(&sr_mutex);
543 	cdrom_release(&cd->cdi, mode);
544 	scsi_cd_put(cd);
545 	mutex_unlock(&sr_mutex);
546 }
547 
548 static int sr_block_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
549 			  unsigned long arg)
550 {
551 	struct scsi_cd *cd = scsi_cd(bdev->bd_disk);
552 	struct scsi_device *sdev = cd->device;
553 	void __user *argp = (void __user *)arg;
554 	int ret;
555 
556 	mutex_lock(&sr_mutex);
557 
558 	/*
559 	 * Send SCSI addressing ioctls directly to mid level, send other
560 	 * ioctls to cdrom/block level.
561 	 */
562 	switch (cmd) {
563 	case SCSI_IOCTL_GET_IDLUN:
564 	case SCSI_IOCTL_GET_BUS_NUMBER:
565 		ret = scsi_ioctl(sdev, cmd, argp);
566 		goto out;
567 	}
568 
569 	ret = cdrom_ioctl(&cd->cdi, bdev, mode, cmd, arg);
570 	if (ret != -ENOSYS)
571 		goto out;
572 
573 	/*
574 	 * ENODEV means that we didn't recognise the ioctl, or that we
575 	 * cannot execute it in the current device state.  In either
576 	 * case fall through to scsi_ioctl, which will return ENDOEV again
577 	 * if it doesn't recognise the ioctl
578 	 */
579 	ret = scsi_nonblockable_ioctl(sdev, cmd, argp,
580 					(mode & FMODE_NDELAY) != 0);
581 	if (ret != -ENODEV)
582 		goto out;
583 	ret = scsi_ioctl(sdev, cmd, argp);
584 
585 out:
586 	mutex_unlock(&sr_mutex);
587 	return ret;
588 }
589 
590 static unsigned int sr_block_check_events(struct gendisk *disk,
591 					  unsigned int clearing)
592 {
593 	struct scsi_cd *cd = scsi_cd(disk);
594 
595 	if (atomic_read(&cd->device->disk_events_disable_depth))
596 		return 0;
597 
598 	return cdrom_check_events(&cd->cdi, clearing);
599 }
600 
601 static int sr_block_revalidate_disk(struct gendisk *disk)
602 {
603 	struct scsi_cd *cd = scsi_cd(disk);
604 	struct scsi_sense_hdr sshdr;
605 
606 	/* if the unit is not ready, nothing more to do */
607 	if (scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES, &sshdr))
608 		goto out;
609 
610 	sr_cd_check(&cd->cdi);
611 	get_sectorsize(cd);
612 out:
613 	return 0;
614 }
615 
616 static const struct block_device_operations sr_bdops =
617 {
618 	.owner		= THIS_MODULE,
619 	.open		= sr_block_open,
620 	.release	= sr_block_release,
621 	.ioctl		= sr_block_ioctl,
622 	.check_events	= sr_block_check_events,
623 	.revalidate_disk = sr_block_revalidate_disk,
624 	/*
625 	 * No compat_ioctl for now because sr_block_ioctl never
626 	 * seems to pass arbitrary ioctls down to host drivers.
627 	 */
628 };
629 
630 static int sr_open(struct cdrom_device_info *cdi, int purpose)
631 {
632 	struct scsi_cd *cd = cdi->handle;
633 	struct scsi_device *sdev = cd->device;
634 	int retval;
635 
636 	/*
637 	 * If the device is in error recovery, wait until it is done.
638 	 * If the device is offline, then disallow any access to it.
639 	 */
640 	retval = -ENXIO;
641 	if (!scsi_block_when_processing_errors(sdev))
642 		goto error_out;
643 
644 	return 0;
645 
646 error_out:
647 	return retval;
648 }
649 
650 static void sr_release(struct cdrom_device_info *cdi)
651 {
652 	struct scsi_cd *cd = cdi->handle;
653 
654 	if (cd->device->sector_size > 2048)
655 		sr_set_blocklength(cd, 2048);
656 
657 }
658 
659 static int sr_probe(struct device *dev)
660 {
661 	struct scsi_device *sdev = to_scsi_device(dev);
662 	struct gendisk *disk;
663 	struct scsi_cd *cd;
664 	int minor, error;
665 
666 	error = -ENODEV;
667 	if (sdev->type != TYPE_ROM && sdev->type != TYPE_WORM)
668 		goto fail;
669 
670 	error = -ENOMEM;
671 	cd = kzalloc(sizeof(*cd), GFP_KERNEL);
672 	if (!cd)
673 		goto fail;
674 
675 	kref_init(&cd->kref);
676 
677 	disk = alloc_disk(1);
678 	if (!disk)
679 		goto fail_free;
680 
681 	spin_lock(&sr_index_lock);
682 	minor = find_first_zero_bit(sr_index_bits, SR_DISKS);
683 	if (minor == SR_DISKS) {
684 		spin_unlock(&sr_index_lock);
685 		error = -EBUSY;
686 		goto fail_put;
687 	}
688 	__set_bit(minor, sr_index_bits);
689 	spin_unlock(&sr_index_lock);
690 
691 	disk->major = SCSI_CDROM_MAJOR;
692 	disk->first_minor = minor;
693 	sprintf(disk->disk_name, "sr%d", minor);
694 	disk->fops = &sr_bdops;
695 	disk->flags = GENHD_FL_CD | GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE;
696 	disk->events = DISK_EVENT_MEDIA_CHANGE | DISK_EVENT_EJECT_REQUEST;
697 
698 	blk_queue_rq_timeout(sdev->request_queue, SR_TIMEOUT);
699 
700 	cd->device = sdev;
701 	cd->disk = disk;
702 	cd->driver = &sr_template;
703 	cd->disk = disk;
704 	cd->capacity = 0x1fffff;
705 	cd->device->changed = 1;	/* force recheck CD type */
706 	cd->media_present = 1;
707 	cd->use = 1;
708 	cd->readcd_known = 0;
709 	cd->readcd_cdda = 0;
710 
711 	cd->cdi.ops = &sr_dops;
712 	cd->cdi.handle = cd;
713 	cd->cdi.mask = 0;
714 	cd->cdi.capacity = 1;
715 	sprintf(cd->cdi.name, "sr%d", minor);
716 
717 	sdev->sector_size = 2048;	/* A guess, just in case */
718 
719 	/* FIXME: need to handle a get_capabilities failure properly ?? */
720 	get_capabilities(cd);
721 	blk_queue_prep_rq(sdev->request_queue, sr_prep_fn);
722 	sr_vendor_init(cd);
723 
724 	disk->driverfs_dev = &sdev->sdev_gendev;
725 	set_capacity(disk, cd->capacity);
726 	disk->private_data = &cd->driver;
727 	disk->queue = sdev->request_queue;
728 	cd->cdi.disk = disk;
729 
730 	if (register_cdrom(&cd->cdi))
731 		goto fail_put;
732 
733 	/*
734 	 * Initialize block layer runtime PM stuffs before the
735 	 * periodic event checking request gets started in add_disk.
736 	 */
737 	blk_pm_runtime_init(sdev->request_queue, dev);
738 
739 	dev_set_drvdata(dev, cd);
740 	disk->flags |= GENHD_FL_REMOVABLE;
741 	add_disk(disk);
742 
743 	sdev_printk(KERN_DEBUG, sdev,
744 		    "Attached scsi CD-ROM %s\n", cd->cdi.name);
745 	scsi_autopm_put_device(cd->device);
746 
747 	return 0;
748 
749 fail_put:
750 	put_disk(disk);
751 fail_free:
752 	kfree(cd);
753 fail:
754 	return error;
755 }
756 
757 
758 static void get_sectorsize(struct scsi_cd *cd)
759 {
760 	unsigned char cmd[10];
761 	unsigned char buffer[8];
762 	int the_result, retries = 3;
763 	int sector_size;
764 	struct request_queue *queue;
765 
766 	do {
767 		cmd[0] = READ_CAPACITY;
768 		memset((void *) &cmd[1], 0, 9);
769 		memset(buffer, 0, sizeof(buffer));
770 
771 		/* Do the command and wait.. */
772 		the_result = scsi_execute_req(cd->device, cmd, DMA_FROM_DEVICE,
773 					      buffer, sizeof(buffer), NULL,
774 					      SR_TIMEOUT, MAX_RETRIES, NULL);
775 
776 		retries--;
777 
778 	} while (the_result && retries);
779 
780 
781 	if (the_result) {
782 		cd->capacity = 0x1fffff;
783 		sector_size = 2048;	/* A guess, just in case */
784 	} else {
785 		long last_written;
786 
787 		cd->capacity = 1 + ((buffer[0] << 24) | (buffer[1] << 16) |
788 				    (buffer[2] << 8) | buffer[3]);
789 		/*
790 		 * READ_CAPACITY doesn't return the correct size on
791 		 * certain UDF media.  If last_written is larger, use
792 		 * it instead.
793 		 *
794 		 * http://bugzilla.kernel.org/show_bug.cgi?id=9668
795 		 */
796 		if (!cdrom_get_last_written(&cd->cdi, &last_written))
797 			cd->capacity = max_t(long, cd->capacity, last_written);
798 
799 		sector_size = (buffer[4] << 24) |
800 		    (buffer[5] << 16) | (buffer[6] << 8) | buffer[7];
801 		switch (sector_size) {
802 			/*
803 			 * HP 4020i CD-Recorder reports 2340 byte sectors
804 			 * Philips CD-Writers report 2352 byte sectors
805 			 *
806 			 * Use 2k sectors for them..
807 			 */
808 		case 0:
809 		case 2340:
810 		case 2352:
811 			sector_size = 2048;
812 			/* fall through */
813 		case 2048:
814 			cd->capacity *= 4;
815 			/* fall through */
816 		case 512:
817 			break;
818 		default:
819 			printk("%s: unsupported sector size %d.\n",
820 			       cd->cdi.name, sector_size);
821 			cd->capacity = 0;
822 		}
823 
824 		cd->device->sector_size = sector_size;
825 
826 		/*
827 		 * Add this so that we have the ability to correctly gauge
828 		 * what the device is capable of.
829 		 */
830 		set_capacity(cd->disk, cd->capacity);
831 	}
832 
833 	queue = cd->device->request_queue;
834 	blk_queue_logical_block_size(queue, sector_size);
835 
836 	return;
837 }
838 
839 static void get_capabilities(struct scsi_cd *cd)
840 {
841 	unsigned char *buffer;
842 	struct scsi_mode_data data;
843 	struct scsi_sense_hdr sshdr;
844 	int rc, n;
845 
846 	static const char *loadmech[] =
847 	{
848 		"caddy",
849 		"tray",
850 		"pop-up",
851 		"",
852 		"changer",
853 		"cartridge changer",
854 		"",
855 		""
856 	};
857 
858 
859 	/* allocate transfer buffer */
860 	buffer = kmalloc(512, GFP_KERNEL | GFP_DMA);
861 	if (!buffer) {
862 		printk(KERN_ERR "sr: out of memory.\n");
863 		return;
864 	}
865 
866 	/* eat unit attentions */
867 	scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES, &sshdr);
868 
869 	/* ask for mode page 0x2a */
870 	rc = scsi_mode_sense(cd->device, 0, 0x2a, buffer, 128,
871 			     SR_TIMEOUT, 3, &data, NULL);
872 
873 	if (!scsi_status_is_good(rc)) {
874 		/* failed, drive doesn't have capabilities mode page */
875 		cd->cdi.speed = 1;
876 		cd->cdi.mask |= (CDC_CD_R | CDC_CD_RW | CDC_DVD_R |
877 				 CDC_DVD | CDC_DVD_RAM |
878 				 CDC_SELECT_DISC | CDC_SELECT_SPEED |
879 				 CDC_MRW | CDC_MRW_W | CDC_RAM);
880 		kfree(buffer);
881 		printk("%s: scsi-1 drive\n", cd->cdi.name);
882 		return;
883 	}
884 
885 	n = data.header_length + data.block_descriptor_length;
886 	cd->cdi.speed = ((buffer[n + 8] << 8) + buffer[n + 9]) / 176;
887 	cd->readcd_known = 1;
888 	cd->readcd_cdda = buffer[n + 5] & 0x01;
889 	/* print some capability bits */
890 	printk("%s: scsi3-mmc drive: %dx/%dx %s%s%s%s%s%s\n", cd->cdi.name,
891 	       ((buffer[n + 14] << 8) + buffer[n + 15]) / 176,
892 	       cd->cdi.speed,
893 	       buffer[n + 3] & 0x01 ? "writer " : "", /* CD Writer */
894 	       buffer[n + 3] & 0x20 ? "dvd-ram " : "",
895 	       buffer[n + 2] & 0x02 ? "cd/rw " : "", /* can read rewriteable */
896 	       buffer[n + 4] & 0x20 ? "xa/form2 " : "",	/* can read xa/from2 */
897 	       buffer[n + 5] & 0x01 ? "cdda " : "", /* can read audio data */
898 	       loadmech[buffer[n + 6] >> 5]);
899 	if ((buffer[n + 6] >> 5) == 0)
900 		/* caddy drives can't close tray... */
901 		cd->cdi.mask |= CDC_CLOSE_TRAY;
902 	if ((buffer[n + 2] & 0x8) == 0)
903 		/* not a DVD drive */
904 		cd->cdi.mask |= CDC_DVD;
905 	if ((buffer[n + 3] & 0x20) == 0)
906 		/* can't write DVD-RAM media */
907 		cd->cdi.mask |= CDC_DVD_RAM;
908 	if ((buffer[n + 3] & 0x10) == 0)
909 		/* can't write DVD-R media */
910 		cd->cdi.mask |= CDC_DVD_R;
911 	if ((buffer[n + 3] & 0x2) == 0)
912 		/* can't write CD-RW media */
913 		cd->cdi.mask |= CDC_CD_RW;
914 	if ((buffer[n + 3] & 0x1) == 0)
915 		/* can't write CD-R media */
916 		cd->cdi.mask |= CDC_CD_R;
917 	if ((buffer[n + 6] & 0x8) == 0)
918 		/* can't eject */
919 		cd->cdi.mask |= CDC_OPEN_TRAY;
920 
921 	if ((buffer[n + 6] >> 5) == mechtype_individual_changer ||
922 	    (buffer[n + 6] >> 5) == mechtype_cartridge_changer)
923 		cd->cdi.capacity =
924 		    cdrom_number_of_slots(&cd->cdi);
925 	if (cd->cdi.capacity <= 1)
926 		/* not a changer */
927 		cd->cdi.mask |= CDC_SELECT_DISC;
928 	/*else    I don't think it can close its tray
929 		cd->cdi.mask |= CDC_CLOSE_TRAY; */
930 
931 	/*
932 	 * if DVD-RAM, MRW-W or CD-RW, we are randomly writable
933 	 */
934 	if ((cd->cdi.mask & (CDC_DVD_RAM | CDC_MRW_W | CDC_RAM | CDC_CD_RW)) !=
935 			(CDC_DVD_RAM | CDC_MRW_W | CDC_RAM | CDC_CD_RW)) {
936 		cd->device->writeable = 1;
937 	}
938 
939 	kfree(buffer);
940 }
941 
942 /*
943  * sr_packet() is the entry point for the generic commands generated
944  * by the Uniform CD-ROM layer.
945  */
946 static int sr_packet(struct cdrom_device_info *cdi,
947 		struct packet_command *cgc)
948 {
949 	struct scsi_cd *cd = cdi->handle;
950 	struct scsi_device *sdev = cd->device;
951 
952 	if (cgc->cmd[0] == GPCMD_READ_DISC_INFO && sdev->no_read_disc_info)
953 		return -EDRIVE_CANT_DO_THIS;
954 
955 	if (cgc->timeout <= 0)
956 		cgc->timeout = IOCTL_TIMEOUT;
957 
958 	sr_do_ioctl(cd, cgc);
959 
960 	return cgc->stat;
961 }
962 
963 /**
964  *	sr_kref_release - Called to free the scsi_cd structure
965  *	@kref: pointer to embedded kref
966  *
967  *	sr_ref_mutex must be held entering this routine.  Because it is
968  *	called on last put, you should always use the scsi_cd_get()
969  *	scsi_cd_put() helpers which manipulate the semaphore directly
970  *	and never do a direct kref_put().
971  **/
972 static void sr_kref_release(struct kref *kref)
973 {
974 	struct scsi_cd *cd = container_of(kref, struct scsi_cd, kref);
975 	struct gendisk *disk = cd->disk;
976 
977 	spin_lock(&sr_index_lock);
978 	clear_bit(MINOR(disk_devt(disk)), sr_index_bits);
979 	spin_unlock(&sr_index_lock);
980 
981 	unregister_cdrom(&cd->cdi);
982 
983 	disk->private_data = NULL;
984 
985 	put_disk(disk);
986 
987 	kfree(cd);
988 }
989 
990 static int sr_remove(struct device *dev)
991 {
992 	struct scsi_cd *cd = dev_get_drvdata(dev);
993 
994 	scsi_autopm_get_device(cd->device);
995 
996 	blk_queue_prep_rq(cd->device->request_queue, scsi_prep_fn);
997 	del_gendisk(cd->disk);
998 
999 	mutex_lock(&sr_ref_mutex);
1000 	kref_put(&cd->kref, sr_kref_release);
1001 	mutex_unlock(&sr_ref_mutex);
1002 
1003 	return 0;
1004 }
1005 
1006 static int __init init_sr(void)
1007 {
1008 	int rc;
1009 
1010 	rc = register_blkdev(SCSI_CDROM_MAJOR, "sr");
1011 	if (rc)
1012 		return rc;
1013 	rc = scsi_register_driver(&sr_template.gendrv);
1014 	if (rc)
1015 		unregister_blkdev(SCSI_CDROM_MAJOR, "sr");
1016 
1017 	return rc;
1018 }
1019 
1020 static void __exit exit_sr(void)
1021 {
1022 	scsi_unregister_driver(&sr_template.gendrv);
1023 	unregister_blkdev(SCSI_CDROM_MAJOR, "sr");
1024 }
1025 
1026 module_init(init_sr);
1027 module_exit(exit_sr);
1028 MODULE_LICENSE("GPL");
1029