xref: /openbmc/linux/drivers/usb/storage/uas.c (revision 63dc02bd)
1 /*
2  * USB Attached SCSI
3  * Note that this is not the same as the USB Mass Storage driver
4  *
5  * Copyright Matthew Wilcox for Intel Corp, 2010
6  * Copyright Sarah Sharp for Intel Corp, 2010
7  *
8  * Distributed under the terms of the GNU GPL, version two.
9  */
10 
11 #include <linux/blkdev.h>
12 #include <linux/slab.h>
13 #include <linux/types.h>
14 #include <linux/module.h>
15 #include <linux/usb.h>
16 #include <linux/usb/hcd.h>
17 #include <linux/usb/storage.h>
18 #include <linux/usb/uas.h>
19 
20 #include <scsi/scsi.h>
21 #include <scsi/scsi_dbg.h>
22 #include <scsi/scsi_cmnd.h>
23 #include <scsi/scsi_device.h>
24 #include <scsi/scsi_host.h>
25 #include <scsi/scsi_tcq.h>
26 
27 /*
28  * The r00-r01c specs define this version of the SENSE IU data structure.
29  * It's still in use by several different firmware releases.
30  */
31 struct sense_iu_old {
32 	__u8 iu_id;
33 	__u8 rsvd1;
34 	__be16 tag;
35 	__be16 len;
36 	__u8 status;
37 	__u8 service_response;
38 	__u8 sense[SCSI_SENSE_BUFFERSIZE];
39 };
40 
41 struct uas_dev_info {
42 	struct usb_interface *intf;
43 	struct usb_device *udev;
44 	int qdepth;
45 	unsigned cmd_pipe, status_pipe, data_in_pipe, data_out_pipe;
46 	unsigned use_streams:1;
47 	unsigned uas_sense_old:1;
48 	struct scsi_cmnd *cmnd;
49 	struct urb *status_urb; /* used only if stream support is available */
50 };
51 
52 enum {
53 	ALLOC_STATUS_URB	= (1 << 0),
54 	SUBMIT_STATUS_URB	= (1 << 1),
55 	ALLOC_DATA_IN_URB	= (1 << 2),
56 	SUBMIT_DATA_IN_URB	= (1 << 3),
57 	ALLOC_DATA_OUT_URB	= (1 << 4),
58 	SUBMIT_DATA_OUT_URB	= (1 << 5),
59 	ALLOC_CMD_URB		= (1 << 6),
60 	SUBMIT_CMD_URB		= (1 << 7),
61 	COMPLETED_DATA_IN	= (1 << 8),
62 	COMPLETED_DATA_OUT	= (1 << 9),
63 	DATA_COMPLETES_CMD	= (1 << 10),
64 };
65 
66 /* Overrides scsi_pointer */
67 struct uas_cmd_info {
68 	unsigned int state;
69 	unsigned int stream;
70 	struct urb *cmd_urb;
71 	/* status_urb is used only if stream support isn't available */
72 	struct urb *status_urb;
73 	struct urb *data_in_urb;
74 	struct urb *data_out_urb;
75 	struct list_head list;
76 };
77 
78 /* I hate forward declarations, but I actually have a loop */
79 static int uas_submit_urbs(struct scsi_cmnd *cmnd,
80 				struct uas_dev_info *devinfo, gfp_t gfp);
81 static void uas_do_work(struct work_struct *work);
82 
83 static DECLARE_WORK(uas_work, uas_do_work);
84 static DEFINE_SPINLOCK(uas_work_lock);
85 static LIST_HEAD(uas_work_list);
86 
87 static void uas_do_work(struct work_struct *work)
88 {
89 	struct uas_cmd_info *cmdinfo;
90 	struct uas_cmd_info *temp;
91 	struct list_head list;
92 	int err;
93 
94 	spin_lock_irq(&uas_work_lock);
95 	list_replace_init(&uas_work_list, &list);
96 	spin_unlock_irq(&uas_work_lock);
97 
98 	list_for_each_entry_safe(cmdinfo, temp, &list, list) {
99 		struct scsi_pointer *scp = (void *)cmdinfo;
100 		struct scsi_cmnd *cmnd = container_of(scp,
101 							struct scsi_cmnd, SCp);
102 		err = uas_submit_urbs(cmnd, cmnd->device->hostdata, GFP_NOIO);
103 		if (err) {
104 			list_del(&cmdinfo->list);
105 			spin_lock_irq(&uas_work_lock);
106 			list_add_tail(&cmdinfo->list, &uas_work_list);
107 			spin_unlock_irq(&uas_work_lock);
108 			schedule_work(&uas_work);
109 		}
110 	}
111 }
112 
113 static void uas_sense(struct urb *urb, struct scsi_cmnd *cmnd)
114 {
115 	struct sense_iu *sense_iu = urb->transfer_buffer;
116 	struct scsi_device *sdev = cmnd->device;
117 	struct uas_cmd_info *cmdinfo = (void *)&cmnd->SCp;
118 
119 	if (urb->actual_length > 16) {
120 		unsigned len = be16_to_cpup(&sense_iu->len);
121 		if (len + 16 != urb->actual_length) {
122 			int newlen = min(len + 16, urb->actual_length) - 16;
123 			if (newlen < 0)
124 				newlen = 0;
125 			sdev_printk(KERN_INFO, sdev, "%s: urb length %d "
126 				"disagrees with IU sense data length %d, "
127 				"using %d bytes of sense data\n", __func__,
128 					urb->actual_length, len, newlen);
129 			len = newlen;
130 		}
131 		memcpy(cmnd->sense_buffer, sense_iu->sense, len);
132 	}
133 
134 	cmnd->result = sense_iu->status;
135 	if (!(cmdinfo->state & DATA_COMPLETES_CMD))
136 		cmnd->scsi_done(cmnd);
137 }
138 
139 static void uas_sense_old(struct urb *urb, struct scsi_cmnd *cmnd)
140 {
141 	struct sense_iu_old *sense_iu = urb->transfer_buffer;
142 	struct scsi_device *sdev = cmnd->device;
143 	struct uas_cmd_info *cmdinfo = (void *)&cmnd->SCp;
144 
145 	if (urb->actual_length > 8) {
146 		unsigned len = be16_to_cpup(&sense_iu->len) - 2;
147 		if (len + 8 != urb->actual_length) {
148 			int newlen = min(len + 8, urb->actual_length) - 8;
149 			if (newlen < 0)
150 				newlen = 0;
151 			sdev_printk(KERN_INFO, sdev, "%s: urb length %d "
152 				"disagrees with IU sense data length %d, "
153 				"using %d bytes of sense data\n", __func__,
154 					urb->actual_length, len, newlen);
155 			len = newlen;
156 		}
157 		memcpy(cmnd->sense_buffer, sense_iu->sense, len);
158 	}
159 
160 	cmnd->result = sense_iu->status;
161 	if (!(cmdinfo->state & DATA_COMPLETES_CMD))
162 		cmnd->scsi_done(cmnd);
163 }
164 
165 static void uas_xfer_data(struct urb *urb, struct scsi_cmnd *cmnd,
166 							unsigned direction)
167 {
168 	struct uas_cmd_info *cmdinfo = (void *)&cmnd->SCp;
169 	int err;
170 
171 	cmdinfo->state = direction;
172 	err = uas_submit_urbs(cmnd, cmnd->device->hostdata, GFP_ATOMIC);
173 	if (err) {
174 		spin_lock(&uas_work_lock);
175 		list_add_tail(&cmdinfo->list, &uas_work_list);
176 		spin_unlock(&uas_work_lock);
177 		schedule_work(&uas_work);
178 	}
179 }
180 
181 static void uas_stat_cmplt(struct urb *urb)
182 {
183 	struct iu *iu = urb->transfer_buffer;
184 	struct Scsi_Host *shost = urb->context;
185 	struct uas_dev_info *devinfo = (void *)shost->hostdata[0];
186 	struct scsi_cmnd *cmnd;
187 	struct uas_cmd_info *cmdinfo;
188 	u16 tag;
189 	int ret;
190 
191 	if (urb->status) {
192 		dev_err(&urb->dev->dev, "URB BAD STATUS %d\n", urb->status);
193 		if (devinfo->use_streams)
194 			usb_free_urb(urb);
195 		return;
196 	}
197 
198 	tag = be16_to_cpup(&iu->tag) - 1;
199 	if (tag == 0)
200 		cmnd = devinfo->cmnd;
201 	else
202 		cmnd = scsi_host_find_tag(shost, tag - 1);
203 	if (!cmnd) {
204 		if (devinfo->use_streams) {
205 			usb_free_urb(urb);
206 			return;
207 		}
208 		ret = usb_submit_urb(urb, GFP_ATOMIC);
209 		if (ret)
210 			dev_err(&urb->dev->dev, "failed submit status urb\n");
211 		return;
212 	}
213 	cmdinfo = (void *)&cmnd->SCp;
214 
215 	switch (iu->iu_id) {
216 	case IU_ID_STATUS:
217 		if (devinfo->cmnd == cmnd)
218 			devinfo->cmnd = NULL;
219 
220 		if (!(cmdinfo->state & COMPLETED_DATA_IN) &&
221 				cmdinfo->data_in_urb) {
222 		       if (devinfo->use_streams) {
223 			       cmdinfo->state |= DATA_COMPLETES_CMD;
224 			       usb_unlink_urb(cmdinfo->data_in_urb);
225 		       } else {
226 			       usb_free_urb(cmdinfo->data_in_urb);
227 		       }
228 		}
229 		if (!(cmdinfo->state & COMPLETED_DATA_OUT) &&
230 				cmdinfo->data_out_urb) {
231 			if (devinfo->use_streams) {
232 				cmdinfo->state |= DATA_COMPLETES_CMD;
233 				usb_unlink_urb(cmdinfo->data_in_urb);
234 			} else {
235 				usb_free_urb(cmdinfo->data_out_urb);
236 			}
237 		}
238 
239 		if (urb->actual_length < 16)
240 			devinfo->uas_sense_old = 1;
241 		if (devinfo->uas_sense_old)
242 			uas_sense_old(urb, cmnd);
243 		else
244 			uas_sense(urb, cmnd);
245 		break;
246 	case IU_ID_READ_READY:
247 		uas_xfer_data(urb, cmnd, SUBMIT_DATA_IN_URB);
248 		break;
249 	case IU_ID_WRITE_READY:
250 		uas_xfer_data(urb, cmnd, SUBMIT_DATA_OUT_URB);
251 		break;
252 	default:
253 		scmd_printk(KERN_ERR, cmnd,
254 			"Bogus IU (%d) received on status pipe\n", iu->iu_id);
255 	}
256 
257 	if (devinfo->use_streams) {
258 		usb_free_urb(urb);
259 		return;
260 	}
261 
262 	ret = usb_submit_urb(urb, GFP_ATOMIC);
263 	if (ret)
264 		dev_err(&urb->dev->dev, "failed submit status urb\n");
265 }
266 
267 static void uas_data_out_cmplt(struct urb *urb)
268 {
269 	struct scsi_cmnd *cmnd = urb->context;
270 	struct scsi_data_buffer *sdb = scsi_out(cmnd);
271 	struct uas_cmd_info *cmdinfo = (void *)&cmnd->SCp;
272 
273 	cmdinfo->state |= COMPLETED_DATA_OUT;
274 
275 	sdb->resid = sdb->length - urb->actual_length;
276 	usb_free_urb(urb);
277 
278 	if (cmdinfo->state & DATA_COMPLETES_CMD)
279 		cmnd->scsi_done(cmnd);
280 }
281 
282 static void uas_data_in_cmplt(struct urb *urb)
283 {
284 	struct scsi_cmnd *cmnd = urb->context;
285 	struct scsi_data_buffer *sdb = scsi_in(cmnd);
286 	struct uas_cmd_info *cmdinfo = (void *)&cmnd->SCp;
287 
288 	cmdinfo->state |= COMPLETED_DATA_IN;
289 
290 	sdb->resid = sdb->length - urb->actual_length;
291 	usb_free_urb(urb);
292 
293 	if (cmdinfo->state & DATA_COMPLETES_CMD)
294 		cmnd->scsi_done(cmnd);
295 }
296 
297 static struct urb *uas_alloc_data_urb(struct uas_dev_info *devinfo, gfp_t gfp,
298 		unsigned int pipe, struct scsi_cmnd *cmnd,
299 		enum dma_data_direction dir)
300 {
301 	struct uas_cmd_info *cmdinfo = (void *)&cmnd->SCp;
302 	struct usb_device *udev = devinfo->udev;
303 	struct urb *urb = usb_alloc_urb(0, gfp);
304 	struct scsi_data_buffer *sdb;
305 	usb_complete_t complete_fn;
306 	u16 stream_id = cmdinfo->stream;
307 
308 	if (!urb)
309 		goto out;
310 	if (dir == DMA_FROM_DEVICE) {
311 		sdb = scsi_in(cmnd);
312 		complete_fn = uas_data_in_cmplt;
313 	} else {
314 		sdb = scsi_out(cmnd);
315 		complete_fn = uas_data_out_cmplt;
316 	}
317 	usb_fill_bulk_urb(urb, udev, pipe, NULL, sdb->length,
318 			complete_fn, cmnd);
319 	urb->stream_id = stream_id;
320 	urb->num_sgs = udev->bus->sg_tablesize ? sdb->table.nents : 0;
321 	urb->sg = sdb->table.sgl;
322  out:
323 	return urb;
324 }
325 
326 static struct urb *uas_alloc_sense_urb(struct uas_dev_info *devinfo, gfp_t gfp,
327 		struct Scsi_Host *shost, u16 stream_id)
328 {
329 	struct usb_device *udev = devinfo->udev;
330 	struct urb *urb = usb_alloc_urb(0, gfp);
331 	struct sense_iu *iu;
332 
333 	if (!urb)
334 		goto out;
335 
336 	iu = kzalloc(sizeof(*iu), gfp);
337 	if (!iu)
338 		goto free;
339 
340 	usb_fill_bulk_urb(urb, udev, devinfo->status_pipe, iu, sizeof(*iu),
341 						uas_stat_cmplt, shost);
342 	urb->stream_id = stream_id;
343 	urb->transfer_flags |= URB_FREE_BUFFER;
344  out:
345 	return urb;
346  free:
347 	usb_free_urb(urb);
348 	return NULL;
349 }
350 
351 static struct urb *uas_alloc_cmd_urb(struct uas_dev_info *devinfo, gfp_t gfp,
352 					struct scsi_cmnd *cmnd, u16 stream_id)
353 {
354 	struct usb_device *udev = devinfo->udev;
355 	struct scsi_device *sdev = cmnd->device;
356 	struct urb *urb = usb_alloc_urb(0, gfp);
357 	struct command_iu *iu;
358 	int len;
359 
360 	if (!urb)
361 		goto out;
362 
363 	len = cmnd->cmd_len - 16;
364 	if (len < 0)
365 		len = 0;
366 	len = ALIGN(len, 4);
367 	iu = kzalloc(sizeof(*iu) + len, gfp);
368 	if (!iu)
369 		goto free;
370 
371 	iu->iu_id = IU_ID_COMMAND;
372 	if (blk_rq_tagged(cmnd->request))
373 		iu->tag = cpu_to_be16(cmnd->request->tag + 2);
374 	else
375 		iu->tag = cpu_to_be16(1);
376 	iu->prio_attr = UAS_SIMPLE_TAG;
377 	iu->len = len;
378 	int_to_scsilun(sdev->lun, &iu->lun);
379 	memcpy(iu->cdb, cmnd->cmnd, cmnd->cmd_len);
380 
381 	usb_fill_bulk_urb(urb, udev, devinfo->cmd_pipe, iu, sizeof(*iu) + len,
382 							usb_free_urb, NULL);
383 	urb->transfer_flags |= URB_FREE_BUFFER;
384  out:
385 	return urb;
386  free:
387 	usb_free_urb(urb);
388 	return NULL;
389 }
390 
391 /*
392  * Why should I request the Status IU before sending the Command IU?  Spec
393  * says to, but also says the device may receive them in any order.  Seems
394  * daft to me.
395  */
396 
397 static int uas_submit_urbs(struct scsi_cmnd *cmnd,
398 					struct uas_dev_info *devinfo, gfp_t gfp)
399 {
400 	struct uas_cmd_info *cmdinfo = (void *)&cmnd->SCp;
401 
402 	if (cmdinfo->state & ALLOC_STATUS_URB) {
403 		cmdinfo->status_urb = uas_alloc_sense_urb(devinfo, gfp,
404 				cmnd->device->host, cmdinfo->stream);
405 		if (!cmdinfo->status_urb)
406 			return SCSI_MLQUEUE_DEVICE_BUSY;
407 		cmdinfo->state &= ~ALLOC_STATUS_URB;
408 	}
409 
410 	if (cmdinfo->state & SUBMIT_STATUS_URB) {
411 		if (usb_submit_urb(cmdinfo->status_urb, gfp)) {
412 			scmd_printk(KERN_INFO, cmnd,
413 					"sense urb submission failure\n");
414 			return SCSI_MLQUEUE_DEVICE_BUSY;
415 		}
416 		cmdinfo->state &= ~SUBMIT_STATUS_URB;
417 	}
418 
419 	if (cmdinfo->state & ALLOC_DATA_IN_URB) {
420 		cmdinfo->data_in_urb = uas_alloc_data_urb(devinfo, gfp,
421 					devinfo->data_in_pipe, cmnd,
422 					DMA_FROM_DEVICE);
423 		if (!cmdinfo->data_in_urb)
424 			return SCSI_MLQUEUE_DEVICE_BUSY;
425 		cmdinfo->state &= ~ALLOC_DATA_IN_URB;
426 	}
427 
428 	if (cmdinfo->state & SUBMIT_DATA_IN_URB) {
429 		if (usb_submit_urb(cmdinfo->data_in_urb, gfp)) {
430 			scmd_printk(KERN_INFO, cmnd,
431 					"data in urb submission failure\n");
432 			return SCSI_MLQUEUE_DEVICE_BUSY;
433 		}
434 		cmdinfo->state &= ~SUBMIT_DATA_IN_URB;
435 	}
436 
437 	if (cmdinfo->state & ALLOC_DATA_OUT_URB) {
438 		cmdinfo->data_out_urb = uas_alloc_data_urb(devinfo, gfp,
439 					devinfo->data_out_pipe, cmnd,
440 					DMA_TO_DEVICE);
441 		if (!cmdinfo->data_out_urb)
442 			return SCSI_MLQUEUE_DEVICE_BUSY;
443 		cmdinfo->state &= ~ALLOC_DATA_OUT_URB;
444 	}
445 
446 	if (cmdinfo->state & SUBMIT_DATA_OUT_URB) {
447 		if (usb_submit_urb(cmdinfo->data_out_urb, gfp)) {
448 			scmd_printk(KERN_INFO, cmnd,
449 					"data out urb submission failure\n");
450 			return SCSI_MLQUEUE_DEVICE_BUSY;
451 		}
452 		cmdinfo->state &= ~SUBMIT_DATA_OUT_URB;
453 	}
454 
455 	if (cmdinfo->state & ALLOC_CMD_URB) {
456 		cmdinfo->cmd_urb = uas_alloc_cmd_urb(devinfo, gfp, cmnd,
457 							cmdinfo->stream);
458 		if (!cmdinfo->cmd_urb)
459 			return SCSI_MLQUEUE_DEVICE_BUSY;
460 		cmdinfo->state &= ~ALLOC_CMD_URB;
461 	}
462 
463 	if (cmdinfo->state & SUBMIT_CMD_URB) {
464 		if (usb_submit_urb(cmdinfo->cmd_urb, gfp)) {
465 			scmd_printk(KERN_INFO, cmnd,
466 					"cmd urb submission failure\n");
467 			return SCSI_MLQUEUE_DEVICE_BUSY;
468 		}
469 		cmdinfo->state &= ~SUBMIT_CMD_URB;
470 	}
471 
472 	return 0;
473 }
474 
475 static int uas_queuecommand_lck(struct scsi_cmnd *cmnd,
476 					void (*done)(struct scsi_cmnd *))
477 {
478 	struct scsi_device *sdev = cmnd->device;
479 	struct uas_dev_info *devinfo = sdev->hostdata;
480 	struct uas_cmd_info *cmdinfo = (void *)&cmnd->SCp;
481 	int err;
482 
483 	BUILD_BUG_ON(sizeof(struct uas_cmd_info) > sizeof(struct scsi_pointer));
484 
485 	if (devinfo->cmnd)
486 		return SCSI_MLQUEUE_DEVICE_BUSY;
487 
488 	if (blk_rq_tagged(cmnd->request)) {
489 		cmdinfo->stream = cmnd->request->tag + 2;
490 	} else {
491 		devinfo->cmnd = cmnd;
492 		cmdinfo->stream = 1;
493 	}
494 
495 	cmnd->scsi_done = done;
496 
497 	cmdinfo->state = ALLOC_STATUS_URB | SUBMIT_STATUS_URB |
498 			ALLOC_CMD_URB | SUBMIT_CMD_URB;
499 
500 	switch (cmnd->sc_data_direction) {
501 	case DMA_FROM_DEVICE:
502 		cmdinfo->state |= ALLOC_DATA_IN_URB | SUBMIT_DATA_IN_URB;
503 		break;
504 	case DMA_BIDIRECTIONAL:
505 		cmdinfo->state |= ALLOC_DATA_IN_URB | SUBMIT_DATA_IN_URB;
506 	case DMA_TO_DEVICE:
507 		cmdinfo->state |= ALLOC_DATA_OUT_URB | SUBMIT_DATA_OUT_URB;
508 	case DMA_NONE:
509 		break;
510 	}
511 
512 	if (!devinfo->use_streams) {
513 		cmdinfo->state &= ~(SUBMIT_DATA_IN_URB | SUBMIT_DATA_OUT_URB |
514 				ALLOC_STATUS_URB | SUBMIT_STATUS_URB);
515 		cmdinfo->stream = 0;
516 	}
517 
518 	err = uas_submit_urbs(cmnd, devinfo, GFP_ATOMIC);
519 	if (err) {
520 		/* If we did nothing, give up now */
521 		if (cmdinfo->state & SUBMIT_STATUS_URB) {
522 			usb_free_urb(cmdinfo->status_urb);
523 			return SCSI_MLQUEUE_DEVICE_BUSY;
524 		}
525 		spin_lock(&uas_work_lock);
526 		list_add_tail(&cmdinfo->list, &uas_work_list);
527 		spin_unlock(&uas_work_lock);
528 		schedule_work(&uas_work);
529 	}
530 
531 	return 0;
532 }
533 
534 static DEF_SCSI_QCMD(uas_queuecommand)
535 
536 static int uas_eh_abort_handler(struct scsi_cmnd *cmnd)
537 {
538 	struct scsi_device *sdev = cmnd->device;
539 	sdev_printk(KERN_INFO, sdev, "%s tag %d\n", __func__,
540 							cmnd->request->tag);
541 
542 /* XXX: Send ABORT TASK Task Management command */
543 	return FAILED;
544 }
545 
546 static int uas_eh_device_reset_handler(struct scsi_cmnd *cmnd)
547 {
548 	struct scsi_device *sdev = cmnd->device;
549 	sdev_printk(KERN_INFO, sdev, "%s tag %d\n", __func__,
550 							cmnd->request->tag);
551 
552 /* XXX: Send LOGICAL UNIT RESET Task Management command */
553 	return FAILED;
554 }
555 
556 static int uas_eh_target_reset_handler(struct scsi_cmnd *cmnd)
557 {
558 	struct scsi_device *sdev = cmnd->device;
559 	sdev_printk(KERN_INFO, sdev, "%s tag %d\n", __func__,
560 							cmnd->request->tag);
561 
562 /* XXX: Can we reset just the one USB interface?
563  * Would calling usb_set_interface() have the right effect?
564  */
565 	return FAILED;
566 }
567 
568 static int uas_eh_bus_reset_handler(struct scsi_cmnd *cmnd)
569 {
570 	struct scsi_device *sdev = cmnd->device;
571 	struct uas_dev_info *devinfo = sdev->hostdata;
572 	struct usb_device *udev = devinfo->udev;
573 
574 	sdev_printk(KERN_INFO, sdev, "%s tag %d\n", __func__,
575 							cmnd->request->tag);
576 
577 	if (usb_reset_device(udev))
578 		return SUCCESS;
579 
580 	return FAILED;
581 }
582 
583 static int uas_slave_alloc(struct scsi_device *sdev)
584 {
585 	sdev->hostdata = (void *)sdev->host->hostdata[0];
586 	return 0;
587 }
588 
589 static int uas_slave_configure(struct scsi_device *sdev)
590 {
591 	struct uas_dev_info *devinfo = sdev->hostdata;
592 	scsi_set_tag_type(sdev, MSG_ORDERED_TAG);
593 	scsi_activate_tcq(sdev, devinfo->qdepth - 2);
594 	return 0;
595 }
596 
597 static struct scsi_host_template uas_host_template = {
598 	.module = THIS_MODULE,
599 	.name = "uas",
600 	.queuecommand = uas_queuecommand,
601 	.slave_alloc = uas_slave_alloc,
602 	.slave_configure = uas_slave_configure,
603 	.eh_abort_handler = uas_eh_abort_handler,
604 	.eh_device_reset_handler = uas_eh_device_reset_handler,
605 	.eh_target_reset_handler = uas_eh_target_reset_handler,
606 	.eh_bus_reset_handler = uas_eh_bus_reset_handler,
607 	.can_queue = 65536,	/* Is there a limit on the _host_ ? */
608 	.this_id = -1,
609 	.sg_tablesize = SG_NONE,
610 	.cmd_per_lun = 1,	/* until we override it */
611 	.skip_settle_delay = 1,
612 	.ordered_tag = 1,
613 };
614 
615 static struct usb_device_id uas_usb_ids[] = {
616 	{ USB_INTERFACE_INFO(USB_CLASS_MASS_STORAGE, USB_SC_SCSI, USB_PR_BULK) },
617 	{ USB_INTERFACE_INFO(USB_CLASS_MASS_STORAGE, USB_SC_SCSI, USB_PR_UAS) },
618 	/* 0xaa is a prototype device I happen to have access to */
619 	{ USB_INTERFACE_INFO(USB_CLASS_MASS_STORAGE, USB_SC_SCSI, 0xaa) },
620 	{ }
621 };
622 MODULE_DEVICE_TABLE(usb, uas_usb_ids);
623 
624 static int uas_is_interface(struct usb_host_interface *intf)
625 {
626 	return (intf->desc.bInterfaceClass == USB_CLASS_MASS_STORAGE &&
627 		intf->desc.bInterfaceSubClass == USB_SC_SCSI &&
628 		intf->desc.bInterfaceProtocol == USB_PR_UAS);
629 }
630 
631 static int uas_isnt_supported(struct usb_device *udev)
632 {
633 	struct usb_hcd *hcd = bus_to_hcd(udev->bus);
634 
635 	dev_warn(&udev->dev, "The driver for the USB controller %s does not "
636 			"support scatter-gather which is\n",
637 			hcd->driver->description);
638 	dev_warn(&udev->dev, "required by the UAS driver. Please try an"
639 			"alternative USB controller if you wish to use UAS.\n");
640 	return -ENODEV;
641 }
642 
643 static int uas_switch_interface(struct usb_device *udev,
644 						struct usb_interface *intf)
645 {
646 	int i;
647 	int sg_supported = udev->bus->sg_tablesize != 0;
648 
649 	for (i = 0; i < intf->num_altsetting; i++) {
650 		struct usb_host_interface *alt = &intf->altsetting[i];
651 
652 		if (uas_is_interface(alt)) {
653 			if (!sg_supported)
654 				return uas_isnt_supported(udev);
655 			return usb_set_interface(udev,
656 						alt->desc.bInterfaceNumber,
657 						alt->desc.bAlternateSetting);
658 		}
659 	}
660 
661 	return -ENODEV;
662 }
663 
664 static void uas_configure_endpoints(struct uas_dev_info *devinfo)
665 {
666 	struct usb_host_endpoint *eps[4] = { };
667 	struct usb_interface *intf = devinfo->intf;
668 	struct usb_device *udev = devinfo->udev;
669 	struct usb_host_endpoint *endpoint = intf->cur_altsetting->endpoint;
670 	unsigned i, n_endpoints = intf->cur_altsetting->desc.bNumEndpoints;
671 
672 	devinfo->uas_sense_old = 0;
673 	devinfo->cmnd = NULL;
674 
675 	for (i = 0; i < n_endpoints; i++) {
676 		unsigned char *extra = endpoint[i].extra;
677 		int len = endpoint[i].extralen;
678 		while (len > 1) {
679 			if (extra[1] == USB_DT_PIPE_USAGE) {
680 				unsigned pipe_id = extra[2];
681 				if (pipe_id > 0 && pipe_id < 5)
682 					eps[pipe_id - 1] = &endpoint[i];
683 				break;
684 			}
685 			len -= extra[0];
686 			extra += extra[0];
687 		}
688 	}
689 
690 	/*
691 	 * Assume that if we didn't find a control pipe descriptor, we're
692 	 * using a device with old firmware that happens to be set up like
693 	 * this.
694 	 */
695 	if (!eps[0]) {
696 		devinfo->cmd_pipe = usb_sndbulkpipe(udev, 1);
697 		devinfo->status_pipe = usb_rcvbulkpipe(udev, 1);
698 		devinfo->data_in_pipe = usb_rcvbulkpipe(udev, 2);
699 		devinfo->data_out_pipe = usb_sndbulkpipe(udev, 2);
700 
701 		eps[1] = usb_pipe_endpoint(udev, devinfo->status_pipe);
702 		eps[2] = usb_pipe_endpoint(udev, devinfo->data_in_pipe);
703 		eps[3] = usb_pipe_endpoint(udev, devinfo->data_out_pipe);
704 	} else {
705 		devinfo->cmd_pipe = usb_sndbulkpipe(udev,
706 						eps[0]->desc.bEndpointAddress);
707 		devinfo->status_pipe = usb_rcvbulkpipe(udev,
708 						eps[1]->desc.bEndpointAddress);
709 		devinfo->data_in_pipe = usb_rcvbulkpipe(udev,
710 						eps[2]->desc.bEndpointAddress);
711 		devinfo->data_out_pipe = usb_sndbulkpipe(udev,
712 						eps[3]->desc.bEndpointAddress);
713 	}
714 
715 	devinfo->qdepth = usb_alloc_streams(devinfo->intf, eps + 1, 3, 256,
716 								GFP_KERNEL);
717 	if (devinfo->qdepth < 0) {
718 		devinfo->qdepth = 256;
719 		devinfo->use_streams = 0;
720 	} else {
721 		devinfo->use_streams = 1;
722 	}
723 }
724 
725 static int uas_alloc_status_urb(struct uas_dev_info *devinfo,
726 		struct Scsi_Host *shost)
727 {
728 	if (devinfo->use_streams) {
729 		devinfo->status_urb = NULL;
730 		return 0;
731 	}
732 
733 	devinfo->status_urb = uas_alloc_sense_urb(devinfo, GFP_KERNEL,
734 			shost, 0);
735 	if (!devinfo->status_urb)
736 		goto err_s_urb;
737 
738 	if (usb_submit_urb(devinfo->status_urb, GFP_KERNEL))
739 		goto err_submit_urb;
740 
741 	return 0;
742 err_submit_urb:
743 	usb_free_urb(devinfo->status_urb);
744 err_s_urb:
745 	return -ENOMEM;
746 }
747 
748 static void uas_free_streams(struct uas_dev_info *devinfo)
749 {
750 	struct usb_device *udev = devinfo->udev;
751 	struct usb_host_endpoint *eps[3];
752 
753 	eps[0] = usb_pipe_endpoint(udev, devinfo->status_pipe);
754 	eps[1] = usb_pipe_endpoint(udev, devinfo->data_in_pipe);
755 	eps[2] = usb_pipe_endpoint(udev, devinfo->data_out_pipe);
756 	usb_free_streams(devinfo->intf, eps, 3, GFP_KERNEL);
757 }
758 
759 /*
760  * XXX: What I'd like to do here is register a SCSI host for each USB host in
761  * the system.  Follow usb-storage's design of registering a SCSI host for
762  * each USB device for the moment.  Can implement this by walking up the
763  * USB hierarchy until we find a USB host.
764  */
765 static int uas_probe(struct usb_interface *intf, const struct usb_device_id *id)
766 {
767 	int result;
768 	struct Scsi_Host *shost;
769 	struct uas_dev_info *devinfo;
770 	struct usb_device *udev = interface_to_usbdev(intf);
771 
772 	if (uas_switch_interface(udev, intf))
773 		return -ENODEV;
774 
775 	devinfo = kmalloc(sizeof(struct uas_dev_info), GFP_KERNEL);
776 	if (!devinfo)
777 		return -ENOMEM;
778 
779 	result = -ENOMEM;
780 	shost = scsi_host_alloc(&uas_host_template, sizeof(void *));
781 	if (!shost)
782 		goto free;
783 
784 	shost->max_cmd_len = 16 + 252;
785 	shost->max_id = 1;
786 	shost->sg_tablesize = udev->bus->sg_tablesize;
787 
788 	devinfo->intf = intf;
789 	devinfo->udev = udev;
790 	uas_configure_endpoints(devinfo);
791 
792 	result = scsi_init_shared_tag_map(shost, devinfo->qdepth - 2);
793 	if (result)
794 		goto free;
795 
796 	result = scsi_add_host(shost, &intf->dev);
797 	if (result)
798 		goto deconfig_eps;
799 
800 	shost->hostdata[0] = (unsigned long)devinfo;
801 
802 	result = uas_alloc_status_urb(devinfo, shost);
803 	if (result)
804 		goto err_alloc_status;
805 
806 	scsi_scan_host(shost);
807 	usb_set_intfdata(intf, shost);
808 	return result;
809 
810 err_alloc_status:
811 	scsi_remove_host(shost);
812 	shost = NULL;
813 deconfig_eps:
814 	uas_free_streams(devinfo);
815  free:
816 	kfree(devinfo);
817 	if (shost)
818 		scsi_host_put(shost);
819 	return result;
820 }
821 
822 static int uas_pre_reset(struct usb_interface *intf)
823 {
824 /* XXX: Need to return 1 if it's not our device in error handling */
825 	return 0;
826 }
827 
828 static int uas_post_reset(struct usb_interface *intf)
829 {
830 /* XXX: Need to return 1 if it's not our device in error handling */
831 	return 0;
832 }
833 
834 static void uas_disconnect(struct usb_interface *intf)
835 {
836 	struct Scsi_Host *shost = usb_get_intfdata(intf);
837 	struct uas_dev_info *devinfo = (void *)shost->hostdata[0];
838 
839 	scsi_remove_host(shost);
840 	usb_kill_urb(devinfo->status_urb);
841 	usb_free_urb(devinfo->status_urb);
842 	uas_free_streams(devinfo);
843 	kfree(devinfo);
844 }
845 
846 /*
847  * XXX: Should this plug into libusual so we can auto-upgrade devices from
848  * Bulk-Only to UAS?
849  */
850 static struct usb_driver uas_driver = {
851 	.name = "uas",
852 	.probe = uas_probe,
853 	.disconnect = uas_disconnect,
854 	.pre_reset = uas_pre_reset,
855 	.post_reset = uas_post_reset,
856 	.id_table = uas_usb_ids,
857 };
858 
859 module_usb_driver(uas_driver);
860 
861 MODULE_LICENSE("GPL");
862 MODULE_AUTHOR("Matthew Wilcox and Sarah Sharp");
863