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15#include <linux/kernel.h>
16#include <linux/errno.h>
17#include <linux/init.h>
18#include <linux/slab.h>
19#include <linux/module.h>
20#include <linux/kref.h>
21#include <linux/uaccess.h>
22#include <linux/usb.h>
23#include <linux/mutex.h>
24
25
26
27#define USB_SKEL_VENDOR_ID 0xfff0
28#define USB_SKEL_PRODUCT_ID 0xfff0
29
30
31static const struct usb_device_id skel_table[] = {
32 { USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) },
33 { }
34};
35MODULE_DEVICE_TABLE(usb, skel_table);
36
37
38
39#define USB_SKEL_MINOR_BASE 192
40
41
42#define MAX_TRANSFER (PAGE_SIZE - 512)
43
44
45
46#define WRITES_IN_FLIGHT 8
47
48
49
50struct usb_skel {
51 struct usb_device *udev;
52 struct usb_interface *interface;
53 struct semaphore limit_sem;
54 struct usb_anchor submitted;
55 struct urb *bulk_in_urb;
56 unsigned char *bulk_in_buffer;
57 size_t bulk_in_size;
58 size_t bulk_in_filled;
59 size_t bulk_in_copied;
60 __u8 bulk_in_endpointAddr;
61 __u8 bulk_out_endpointAddr;
62 int errors;
63 bool ongoing_read;
64 bool processed_urb;
65 spinlock_t err_lock;
66 struct kref kref;
67 struct mutex io_mutex;
68 struct completion bulk_in_completion;
69};
70#define to_skel_dev(d) container_of(d, struct usb_skel, kref)
71
72static struct usb_driver skel_driver;
73static void skel_draw_down(struct usb_skel *dev);
74
75static void skel_delete(struct kref *kref)
76{
77 struct usb_skel *dev = to_skel_dev(kref);
78
79 usb_free_urb(dev->bulk_in_urb);
80 usb_put_dev(dev->udev);
81 kfree(dev->bulk_in_buffer);
82 kfree(dev);
83}
84
85static int skel_open(struct inode *inode, struct file *file)
86{
87 struct usb_skel *dev;
88 struct usb_interface *interface;
89 int subminor;
90 int retval = 0;
91
92 subminor = iminor(inode);
93
94 interface = usb_find_interface(&skel_driver, subminor);
95 if (!interface) {
96 pr_err("%s - error, can't find device for minor %d\n",
97 __func__, subminor);
98 retval = -ENODEV;
99 goto exit;
100 }
101
102 dev = usb_get_intfdata(interface);
103 if (!dev) {
104 retval = -ENODEV;
105 goto exit;
106 }
107
108
109 kref_get(&dev->kref);
110
111
112
113 mutex_lock(&dev->io_mutex);
114
115 retval = usb_autopm_get_interface(interface);
116 if (retval)
117 goto out_err;
118
119
120 file->private_data = dev;
121 mutex_unlock(&dev->io_mutex);
122
123exit:
124 return retval;
125}
126
127static int skel_release(struct inode *inode, struct file *file)
128{
129 struct usb_skel *dev;
130
131 dev = file->private_data;
132 if (dev == NULL)
133 return -ENODEV;
134
135
136 mutex_lock(&dev->io_mutex);
137 if (dev->interface)
138 usb_autopm_put_interface(dev->interface);
139 mutex_unlock(&dev->io_mutex);
140
141
142 kref_put(&dev->kref, skel_delete);
143 return 0;
144}
145
146static int skel_flush(struct file *file, fl_owner_t id)
147{
148 struct usb_skel *dev;
149 int res;
150
151 dev = file->private_data;
152 if (dev == NULL)
153 return -ENODEV;
154
155
156 mutex_lock(&dev->io_mutex);
157 skel_draw_down(dev);
158
159
160 spin_lock_irq(&dev->err_lock);
161 res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0;
162 dev->errors = 0;
163 spin_unlock_irq(&dev->err_lock);
164
165 mutex_unlock(&dev->io_mutex);
166
167 return res;
168}
169
170static void skel_read_bulk_callback(struct urb *urb)
171{
172 struct usb_skel *dev;
173
174 dev = urb->context;
175
176 spin_lock(&dev->err_lock);
177
178 if (urb->status) {
179 if (!(urb->status == -ENOENT ||
180 urb->status == -ECONNRESET ||
181 urb->status == -ESHUTDOWN))
182 dev_err(&dev->interface->dev,
183 "%s - nonzero write bulk status received: %d\n",
184 __func__, urb->status);
185
186 dev->errors = urb->status;
187 } else {
188 dev->bulk_in_filled = urb->actual_length;
189 }
190 dev->ongoing_read = 0;
191 spin_unlock(&dev->err_lock);
192
193 complete(&dev->bulk_in_completion);
194}
195
196static int skel_do_read_io(struct usb_skel *dev, size_t count)
197{
198 int rv;
199
200
201 usb_fill_bulk_urb(dev->bulk_in_urb,
202 dev->udev,
203 usb_rcvbulkpipe(dev->udev,
204 dev->bulk_in_endpointAddr),
205 dev->bulk_in_buffer,
206 min(dev->bulk_in_size, count),
207 skel_read_bulk_callback,
208 dev);
209
210 spin_lock_irq(&dev->err_lock);
211 dev->ongoing_read = 1;
212 spin_unlock_irq(&dev->err_lock);
213
214
215 rv = usb_submit_urb(dev->bulk_in_urb, GFP_KERNEL);
216 if (rv < 0) {
217 dev_err(&dev->interface->dev,
218 "%s - failed submitting read urb, error %d\n",
219 __func__, rv);
220 dev->bulk_in_filled = 0;
221 rv = (rv == -ENOMEM) ? rv : -EIO;
222 spin_lock_irq(&dev->err_lock);
223 dev->ongoing_read = 0;
224 spin_unlock_irq(&dev->err_lock);
225 }
226
227 return rv;
228}
229
230static ssize_t skel_read(struct file *file, char *buffer, size_t count,
231 loff_t *ppos)
232{
233 struct usb_skel *dev;
234 int rv;
235 bool ongoing_io;
236
237 dev = file->private_data;
238
239
240 if (!dev->bulk_in_urb || !count)
241 return 0;
242
243
244 rv = mutex_lock_interruptible(&dev->io_mutex);
245 if (rv < 0)
246 return rv;
247
248 if (!dev->interface) {
249 rv = -ENODEV;
250 goto exit;
251 }
252
253
254retry:
255 spin_lock_irq(&dev->err_lock);
256 ongoing_io = dev->ongoing_read;
257 spin_unlock_irq(&dev->err_lock);
258
259 if (ongoing_io) {
260
261 if (file->f_flags & O_NONBLOCK) {
262 rv = -EAGAIN;
263 goto exit;
264 }
265
266
267
268
269 rv = wait_for_completion_interruptible(&dev->bulk_in_completion);
270 if (rv < 0)
271 goto exit;
272
273
274
275
276 dev->bulk_in_copied = 0;
277 dev->processed_urb = 1;
278 }
279
280 if (!dev->processed_urb) {
281
282
283
284
285 wait_for_completion(&dev->bulk_in_completion);
286 dev->bulk_in_copied = 0;
287 dev->processed_urb = 1;
288 }
289
290
291 rv = dev->errors;
292 if (rv < 0) {
293
294 dev->errors = 0;
295
296 rv = (rv == -EPIPE) ? rv : -EIO;
297
298 dev->bulk_in_filled = 0;
299
300 goto exit;
301 }
302
303
304
305
306
307
308 if (dev->bulk_in_filled) {
309
310 size_t available = dev->bulk_in_filled - dev->bulk_in_copied;
311 size_t chunk = min(available, count);
312
313 if (!available) {
314
315
316
317
318 rv = skel_do_read_io(dev, count);
319 if (rv < 0)
320 goto exit;
321 else
322 goto retry;
323 }
324
325
326
327
328
329 if (copy_to_user(buffer,
330 dev->bulk_in_buffer + dev->bulk_in_copied,
331 chunk))
332 rv = -EFAULT;
333 else
334 rv = chunk;
335
336 dev->bulk_in_copied += chunk;
337
338
339
340
341
342 if (available < count)
343 skel_do_read_io(dev, count - chunk);
344 } else {
345
346 rv = skel_do_read_io(dev, count);
347 if (rv < 0)
348 goto exit;
349 else if (!(file->f_flags & O_NONBLOCK))
350 goto retry;
351 rv = -EAGAIN;
352 }
353exit:
354 mutex_unlock(&dev->io_mutex);
355 return rv;
356}
357
358static void skel_write_bulk_callback(struct urb *urb)
359{
360 struct usb_skel *dev;
361
362 dev = urb->context;
363
364
365 if (urb->status) {
366 if (!(urb->status == -ENOENT ||
367 urb->status == -ECONNRESET ||
368 urb->status == -ESHUTDOWN))
369 dev_err(&dev->interface->dev,
370 "%s - nonzero write bulk status received: %d\n",
371 __func__, urb->status);
372
373 spin_lock(&dev->err_lock);
374 dev->errors = urb->status;
375 spin_unlock(&dev->err_lock);
376 }
377
378
379 usb_free_coherent(urb->dev, urb->transfer_buffer_length,
380 urb->transfer_buffer, urb->transfer_dma);
381 up(&dev->limit_sem);
382}
383
384static ssize_t skel_write(struct file *file, const char *user_buffer,
385 size_t count, loff_t *ppos)
386{
387 struct usb_skel *dev;
388 int retval = 0;
389 struct urb *urb = NULL;
390 char *buf = NULL;
391 size_t writesize = min(count, (size_t)MAX_TRANSFER);
392
393 dev = file->private_data;
394
395
396 if (count == 0)
397 goto exit;
398
399
400
401
402
403 if (!(file->f_flags & O_NONBLOCK)) {
404 if (down_interruptible(&dev->limit_sem)) {
405 retval = -ERESTARTSYS;
406 goto exit;
407 }
408 } else {
409 if (down_trylock(&dev->limit_sem)) {
410 retval = -EAGAIN;
411 goto exit;
412 }
413 }
414
415 spin_lock_irq(&dev->err_lock);
416 retval = dev->errors;
417 if (retval < 0) {
418
419 dev->errors = 0;
420
421 retval = (retval == -EPIPE) ? retval : -EIO;
422 }
423 spin_unlock_irq(&dev->err_lock);
424 if (retval < 0)
425 goto error;
426
427
428 urb = usb_alloc_urb(0, GFP_KERNEL);
429 if (!urb) {
430 retval = -ENOMEM;
431 goto error;
432 }
433
434 buf = usb_alloc_coherent(dev->udev, writesize, GFP_KERNEL,
435 &urb->transfer_dma);
436 if (!buf) {
437 retval = -ENOMEM;
438 goto error;
439 }
440
441 if (copy_from_user(buf, user_buffer, writesize)) {
442 retval = -EFAULT;
443 goto error;
444 }
445
446
447 mutex_lock(&dev->io_mutex);
448 if (!dev->interface) {
449 mutex_unlock(&dev->io_mutex);
450 retval = -ENODEV;
451 goto error;
452 }
453
454
455 usb_fill_bulk_urb(urb, dev->udev,
456 usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
457 buf, writesize, skel_write_bulk_callback, dev);
458 urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
459 usb_anchor_urb(urb, &dev->submitted);
460
461
462 retval = usb_submit_urb(urb, GFP_KERNEL);
463 mutex_unlock(&dev->io_mutex);
464 if (retval) {
465 dev_err(&dev->interface->dev,
466 "%s - failed submitting write urb, error %d\n",
467 __func__, retval);
468 goto error_unanchor;
469 }
470
471
472
473
474
475 usb_free_urb(urb);
476
477
478 return writesize;
479
480error_unanchor:
481 usb_unanchor_urb(urb);
482error:
483 if (urb) {
484 usb_free_coherent(dev->udev, writesize, buf, urb->transfer_dma);
485 usb_free_urb(urb);
486 }
487 up(&dev->limit_sem);
488
489exit:
490 return retval;
491}
492
493static const struct file_operations skel_fops = {
494 .owner = THIS_MODULE,
495 .read = skel_read,
496 .write = skel_write,
497 .open = skel_open,
498 .release = skel_release,
499 .flush = skel_flush,
500 .llseek = noop_llseek,
501};
502
503
504
505
506
507static struct usb_class_driver skel_class = {
508 .name = "skel%d",
509 .fops = &skel_fops,
510 .minor_base = USB_SKEL_MINOR_BASE,
511};
512
513static int skel_probe(struct usb_interface *interface,
514 const struct usb_device_id *id)
515{
516 struct usb_skel *dev;
517 struct usb_host_interface *iface_desc;
518 struct usb_endpoint_descriptor *endpoint;
519 size_t buffer_size;
520 int i;
521 int retval = -ENOMEM;
522
523
524 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
525 if (!dev) {
526 dev_err(&interface->dev, "Out of memory\n");
527 goto error;
528 }
529 kref_init(&dev->kref);
530 sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
531 mutex_init(&dev->io_mutex);
532 spin_lock_init(&dev->err_lock);
533 init_usb_anchor(&dev->submitted);
534 init_completion(&dev->bulk_in_completion);
535
536 dev->udev = usb_get_dev(interface_to_usbdev(interface));
537 dev->interface = interface;
538
539
540
541 iface_desc = interface->cur_altsetting;
542 for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
543 endpoint = &iface_desc->endpoint[i].desc;
544
545 if (!dev->bulk_in_endpointAddr &&
546 usb_endpoint_is_bulk_in(endpoint)) {
547
548 buffer_size = usb_endpoint_maxp(endpoint);
549 dev->bulk_in_size = buffer_size;
550 dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
551 dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
552 if (!dev->bulk_in_buffer) {
553 dev_err(&interface->dev,
554 "Could not allocate bulk_in_buffer\n");
555 goto error;
556 }
557 dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL);
558 if (!dev->bulk_in_urb) {
559 dev_err(&interface->dev,
560 "Could not allocate bulk_in_urb\n");
561 goto error;
562 }
563 }
564
565 if (!dev->bulk_out_endpointAddr &&
566 usb_endpoint_is_bulk_out(endpoint)) {
567
568 dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
569 }
570 }
571 if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
572 dev_err(&interface->dev,
573 "Could not find both bulk-in and bulk-out endpoints\n");
574 goto error;
575 }
576
577
578 usb_set_intfdata(interface, dev);
579
580
581 retval = usb_register_dev(interface, &skel_class);
582 if (retval) {
583
584 dev_err(&interface->dev,
585 "Not able to get a minor for this device.\n");
586 usb_set_intfdata(interface, NULL);
587 goto error;
588 }
589
590
591 dev_info(&interface->dev,
592 "USB Skeleton device now attached to USBSkel-%d",
593 interface->minor);
594 return 0;
595
596error:
597 if (dev)
598
599 kref_put(&dev->kref, skel_delete);
600 return retval;
601}
602
603static void skel_disconnect(struct usb_interface *interface)
604{
605 struct usb_skel *dev;
606 int minor = interface->minor;
607
608 dev = usb_get_intfdata(interface);
609 usb_set_intfdata(interface, NULL);
610
611
612 usb_deregister_dev(interface, &skel_class);
613
614
615 mutex_lock(&dev->io_mutex);
616 dev->interface = NULL;
617 mutex_unlock(&dev->io_mutex);
618
619 usb_kill_anchored_urbs(&dev->submitted);
620
621
622 kref_put(&dev->kref, skel_delete);
623
624 dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor);
625}
626
627static void skel_draw_down(struct usb_skel *dev)
628{
629 int time;
630
631 time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
632 if (!time)
633 usb_kill_anchored_urbs(&dev->submitted);
634 usb_kill_urb(dev->bulk_in_urb);
635}
636
637static int skel_suspend(struct usb_interface *intf, pm_message_t message)
638{
639 struct usb_skel *dev = usb_get_intfdata(intf);
640
641 if (!dev)
642 return 0;
643 skel_draw_down(dev);
644 return 0;
645}
646
647static int skel_resume(struct usb_interface *intf)
648{
649 return 0;
650}
651
652static int skel_pre_reset(struct usb_interface *intf)
653{
654 struct usb_skel *dev = usb_get_intfdata(intf);
655
656 mutex_lock(&dev->io_mutex);
657 skel_draw_down(dev);
658
659 return 0;
660}
661
662static int skel_post_reset(struct usb_interface *intf)
663{
664 struct usb_skel *dev = usb_get_intfdata(intf);
665
666
667 dev->errors = -EPIPE;
668 mutex_unlock(&dev->io_mutex);
669
670 return 0;
671}
672
673static struct usb_driver skel_driver = {
674 .name = "skeleton",
675 .probe = skel_probe,
676 .disconnect = skel_disconnect,
677 .suspend = skel_suspend,
678 .resume = skel_resume,
679 .pre_reset = skel_pre_reset,
680 .post_reset = skel_post_reset,
681 .id_table = skel_table,
682 .supports_autosuspend = 1,
683};
684
685module_usb_driver(skel_driver);
686
687MODULE_LICENSE("GPL");
688