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1/*
2 * USB Skeleton driver - 2.2
3 *
4 * Copyright (C) 2001-2004 Greg Kroah-Hartman (greg@kroah.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License as
8 * published by the Free Software Foundation, version 2.
9 *
10 * This driver is based on the 2.6.3 version of drivers/usb/usb-skeleton.c
11 * but has been rewritten to be easier to read and use.
12 *
13 */
14
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/* Define these values to match your devices */
27#define USB_SKEL_VENDOR_ID 0xfff0
28#define USB_SKEL_PRODUCT_ID 0xfff0
29
30/* table of devices that work with this driver */
31static const struct usb_device_id skel_table[] = {
32 { USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) },
33 { } /* Terminating entry */
34};
35MODULE_DEVICE_TABLE(usb, skel_table);
36
37
38/* Get a minor range for your devices from the usb maintainer */
39#define USB_SKEL_MINOR_BASE 192
40
41/* our private defines. if this grows any larger, use your own .h file */
42#define MAX_TRANSFER (PAGE_SIZE - 512)
43/* MAX_TRANSFER is chosen so that the VM is not stressed by
44 allocations > PAGE_SIZE and the number of packets in a page
45 is an integer 512 is the largest possible packet on EHCI */
46#define WRITES_IN_FLIGHT 8
47/* arbitrarily chosen */
48
49/* Structure to hold all of our device specific stuff */
50struct usb_skel {
51 struct usb_device *udev; /* the usb device for this device */
52 struct usb_interface *interface; /* the interface for this device */
53 struct semaphore limit_sem; /* limiting the number of writes in progress */
54 struct usb_anchor submitted; /* in case we need to retract our submissions */
55 struct urb *bulk_in_urb; /* the urb to read data with */
56 unsigned char *bulk_in_buffer; /* the buffer to receive data */
57 size_t bulk_in_size; /* the size of the receive buffer */
58 size_t bulk_in_filled; /* number of bytes in the buffer */
59 size_t bulk_in_copied; /* already copied to user space */
60 __u8 bulk_in_endpointAddr; /* the address of the bulk in endpoint */
61 __u8 bulk_out_endpointAddr; /* the address of the bulk out endpoint */
62 int errors; /* the last request tanked */
63 int open_count; /* count the number of openers */
64 bool ongoing_read; /* a read is going on */
65 bool processed_urb; /* indicates we haven't processed the urb */
66 spinlock_t err_lock; /* lock for errors */
67 struct kref kref;
68 struct mutex io_mutex; /* synchronize I/O with disconnect */
69 struct completion bulk_in_completion; /* to wait for an ongoing read */
70};
71#define to_skel_dev(d) container_of(d, struct usb_skel, kref)
72
73static struct usb_driver skel_driver;
74static void skel_draw_down(struct usb_skel *dev);
75
76static void skel_delete(struct kref *kref)
77{
78 struct usb_skel *dev = to_skel_dev(kref);
79
80 usb_free_urb(dev->bulk_in_urb);
81 usb_put_dev(dev->udev);
82 kfree(dev->bulk_in_buffer);
83 kfree(dev);
84}
85
86static int skel_open(struct inode *inode, struct file *file)
87{
88 struct usb_skel *dev;
89 struct usb_interface *interface;
90 int subminor;
91 int retval = 0;
92
93 subminor = iminor(inode);
94
95 interface = usb_find_interface(&skel_driver, subminor);
96 if (!interface) {
97 err("%s - error, can't find device for minor %d",
98 __func__, subminor);
99 retval = -ENODEV;
100 goto exit;
101 }
102
103 dev = usb_get_intfdata(interface);
104 if (!dev) {
105 retval = -ENODEV;
106 goto exit;
107 }
108
109 /* increment our usage count for the device */
110 kref_get(&dev->kref);
111
112 /* lock the device to allow correctly handling errors
113 * in resumption */
114 mutex_lock(&dev->io_mutex);
115
116 if (!dev->open_count++) {
117 retval = usb_autopm_get_interface(interface);
118 if (retval) {
119 dev->open_count--;
120 mutex_unlock(&dev->io_mutex);
121 kref_put(&dev->kref, skel_delete);
122 goto exit;
123 }
124 } /* else { //uncomment this block if you want exclusive open
125 retval = -EBUSY;
126 dev->open_count--;
127 mutex_unlock(&dev->io_mutex);
128 kref_put(&dev->kref, skel_delete);
129 goto exit;
130 } */
131 /* prevent the device from being autosuspended */
132
133 /* save our object in the file's private structure */
134 file->private_data = dev;
135 mutex_unlock(&dev->io_mutex);
136
137exit:
138 return retval;
139}
140
141static int skel_release(struct inode *inode, struct file *file)
142{
143 struct usb_skel *dev;
144
145 dev = file->private_data;
146 if (dev == NULL)
147 return -ENODEV;
148
149 /* allow the device to be autosuspended */
150 mutex_lock(&dev->io_mutex);
151 if (!--dev->open_count && dev->interface)
152 usb_autopm_put_interface(dev->interface);
153 mutex_unlock(&dev->io_mutex);
154
155 /* decrement the count on our device */
156 kref_put(&dev->kref, skel_delete);
157 return 0;
158}
159
160static int skel_flush(struct file *file, fl_owner_t id)
161{
162 struct usb_skel *dev;
163 int res;
164
165 dev = file->private_data;
166 if (dev == NULL)
167 return -ENODEV;
168
169 /* wait for io to stop */
170 mutex_lock(&dev->io_mutex);
171 skel_draw_down(dev);
172
173 /* read out errors, leave subsequent opens a clean slate */
174 spin_lock_irq(&dev->err_lock);
175 res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0;
176 dev->errors = 0;
177 spin_unlock_irq(&dev->err_lock);
178
179 mutex_unlock(&dev->io_mutex);
180
181 return res;
182}
183
184static void skel_read_bulk_callback(struct urb *urb)
185{
186 struct usb_skel *dev;
187
188 dev = urb->context;
189
190 spin_lock(&dev->err_lock);
191 /* sync/async unlink faults aren't errors */
192 if (urb->status) {
193 if (!(urb->status == -ENOENT ||
194 urb->status == -ECONNRESET ||
195 urb->status == -ESHUTDOWN))
196 err("%s - nonzero write bulk status received: %d",
197 __func__, urb->status);
198
199 dev->errors = urb->status;
200 } else {
201 dev->bulk_in_filled = urb->actual_length;
202 }
203 dev->ongoing_read = 0;
204 spin_unlock(&dev->err_lock);
205
206 complete(&dev->bulk_in_completion);
207}
208
209static int skel_do_read_io(struct usb_skel *dev, size_t count)
210{
211 int rv;
212
213 /* prepare a read */
214 usb_fill_bulk_urb(dev->bulk_in_urb,
215 dev->udev,
216 usb_rcvbulkpipe(dev->udev,
217 dev->bulk_in_endpointAddr),
218 dev->bulk_in_buffer,
219 min(dev->bulk_in_size, count),
220 skel_read_bulk_callback,
221 dev);
222 /* tell everybody to leave the URB alone */
223 spin_lock_irq(&dev->err_lock);
224 dev->ongoing_read = 1;
225 spin_unlock_irq(&dev->err_lock);
226
227 /* do it */
228 rv = usb_submit_urb(dev->bulk_in_urb, GFP_KERNEL);
229 if (rv < 0) {
230 err("%s - failed submitting read urb, error %d",
231 __func__, rv);
232 dev->bulk_in_filled = 0;
233 rv = (rv == -ENOMEM) ? rv : -EIO;
234 spin_lock_irq(&dev->err_lock);
235 dev->ongoing_read = 0;
236 spin_unlock_irq(&dev->err_lock);
237 }
238
239 return rv;
240}
241
242static ssize_t skel_read(struct file *file, char *buffer, size_t count,
243 loff_t *ppos)
244{
245 struct usb_skel *dev;
246 int rv;
247 bool ongoing_io;
248
249 dev = file->private_data;
250
251 /* if we cannot read at all, return EOF */
252 if (!dev->bulk_in_urb || !count)
253 return 0;
254
255 /* no concurrent readers */
256 rv = mutex_lock_interruptible(&dev->io_mutex);
257 if (rv < 0)
258 return rv;
259
260 if (!dev->interface) { /* disconnect() was called */
261 rv = -ENODEV;
262 goto exit;
263 }
264
265 /* if IO is under way, we must not touch things */
266retry:
267 spin_lock_irq(&dev->err_lock);
268 ongoing_io = dev->ongoing_read;
269 spin_unlock_irq(&dev->err_lock);
270
271 if (ongoing_io) {
272 /* nonblocking IO shall not wait */
273 if (file->f_flags & O_NONBLOCK) {
274 rv = -EAGAIN;
275 goto exit;
276 }
277 /*
278 * IO may take forever
279 * hence wait in an interruptible state
280 */
281 rv = wait_for_completion_interruptible(&dev->bulk_in_completion);
282 if (rv < 0)
283 goto exit;
284 /*
285 * by waiting we also semiprocessed the urb
286 * we must finish now
287 */
288 dev->bulk_in_copied = 0;
289 dev->processed_urb = 1;
290 }
291
292 if (!dev->processed_urb) {
293 /*
294 * the URB hasn't been processed
295 * do it now
296 */
297 wait_for_completion(&dev->bulk_in_completion);
298 dev->bulk_in_copied = 0;
299 dev->processed_urb = 1;
300 }
301
302 /* errors must be reported */
303 rv = dev->errors;
304 if (rv < 0) {
305 /* any error is reported once */
306 dev->errors = 0;
307 /* to preserve notifications about reset */
308 rv = (rv == -EPIPE) ? rv : -EIO;
309 /* no data to deliver */
310 dev->bulk_in_filled = 0;
311 /* report it */
312 goto exit;
313 }
314
315 /*
316 * if the buffer is filled we may satisfy the read
317 * else we need to start IO
318 */
319
320 if (dev->bulk_in_filled) {
321 /* we had read data */
322 size_t available = dev->bulk_in_filled - dev->bulk_in_copied;
323 size_t chunk = min(available, count);
324
325 if (!available) {
326 /*
327 * all data has been used
328 * actual IO needs to be done
329 */
330 rv = skel_do_read_io(dev, count);
331 if (rv < 0)
332 goto exit;
333 else
334 goto retry;
335 }
336 /*
337 * data is available
338 * chunk tells us how much shall be copied
339 */
340
341 if (copy_to_user(buffer,
342 dev->bulk_in_buffer + dev->bulk_in_copied,
343 chunk))
344 rv = -EFAULT;
345 else
346 rv = chunk;
347
348 dev->bulk_in_copied += chunk;
349
350 /*
351 * if we are asked for more than we have,
352 * we start IO but don't wait
353 */
354 if (available < count)
355 skel_do_read_io(dev, count - chunk);
356 } else {
357 /* no data in the buffer */
358 rv = skel_do_read_io(dev, count);
359 if (rv < 0)
360 goto exit;
361 else if (!(file->f_flags & O_NONBLOCK))
362 goto retry;
363 rv = -EAGAIN;
364 }
365exit:
366 mutex_unlock(&dev->io_mutex);
367 return rv;
368}
369
370static void skel_write_bulk_callback(struct urb *urb)
371{
372 struct usb_skel *dev;
373
374 dev = urb->context;
375
376 /* sync/async unlink faults aren't errors */
377 if (urb->status) {
378 if (!(urb->status == -ENOENT ||
379 urb->status == -ECONNRESET ||
380 urb->status == -ESHUTDOWN))
381 err("%s - nonzero write bulk status received: %d",
382 __func__, urb->status);
383
384 spin_lock(&dev->err_lock);
385 dev->errors = urb->status;
386 spin_unlock(&dev->err_lock);
387 }
388
389 /* free up our allocated buffer */
390 usb_free_coherent(urb->dev, urb->transfer_buffer_length,
391 urb->transfer_buffer, urb->transfer_dma);
392 up(&dev->limit_sem);
393}
394
395static ssize_t skel_write(struct file *file, const char *user_buffer,
396 size_t count, loff_t *ppos)
397{
398 struct usb_skel *dev;
399 int retval = 0;
400 struct urb *urb = NULL;
401 char *buf = NULL;
402 size_t writesize = min(count, (size_t)MAX_TRANSFER);
403
404 dev = file->private_data;
405
406 /* verify that we actually have some data to write */
407 if (count == 0)
408 goto exit;
409
410 /*
411 * limit the number of URBs in flight to stop a user from using up all
412 * RAM
413 */
414 if (!(file->f_flags & O_NONBLOCK)) {
415 if (down_interruptible(&dev->limit_sem)) {
416 retval = -ERESTARTSYS;
417 goto exit;
418 }
419 } else {
420 if (down_trylock(&dev->limit_sem)) {
421 retval = -EAGAIN;
422 goto exit;
423 }
424 }
425
426 spin_lock_irq(&dev->err_lock);
427 retval = dev->errors;
428 if (retval < 0) {
429 /* any error is reported once */
430 dev->errors = 0;
431 /* to preserve notifications about reset */
432 retval = (retval == -EPIPE) ? retval : -EIO;
433 }
434 spin_unlock_irq(&dev->err_lock);
435 if (retval < 0)
436 goto error;
437
438 /* create a urb, and a buffer for it, and copy the data to the urb */
439 urb = usb_alloc_urb(0, GFP_KERNEL);
440 if (!urb) {
441 retval = -ENOMEM;
442 goto error;
443 }
444
445 buf = usb_alloc_coherent(dev->udev, writesize, GFP_KERNEL,
446 &urb->transfer_dma);
447 if (!buf) {
448 retval = -ENOMEM;
449 goto error;
450 }
451
452 if (copy_from_user(buf, user_buffer, writesize)) {
453 retval = -EFAULT;
454 goto error;
455 }
456
457 /* this lock makes sure we don't submit URBs to gone devices */
458 mutex_lock(&dev->io_mutex);
459 if (!dev->interface) { /* disconnect() was called */
460 mutex_unlock(&dev->io_mutex);
461 retval = -ENODEV;
462 goto error;
463 }
464
465 /* initialize the urb properly */
466 usb_fill_bulk_urb(urb, dev->udev,
467 usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
468 buf, writesize, skel_write_bulk_callback, dev);
469 urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
470 usb_anchor_urb(urb, &dev->submitted);
471
472 /* send the data out the bulk port */
473 retval = usb_submit_urb(urb, GFP_KERNEL);
474 mutex_unlock(&dev->io_mutex);
475 if (retval) {
476 err("%s - failed submitting write urb, error %d", __func__,
477 retval);
478 goto error_unanchor;
479 }
480
481 /*
482 * release our reference to this urb, the USB core will eventually free
483 * it entirely
484 */
485 usb_free_urb(urb);
486
487
488 return writesize;
489
490error_unanchor:
491 usb_unanchor_urb(urb);
492error:
493 if (urb) {
494 usb_free_coherent(dev->udev, writesize, buf, urb->transfer_dma);
495 usb_free_urb(urb);
496 }
497 up(&dev->limit_sem);
498
499exit:
500 return retval;
501}
502
503static const struct file_operations skel_fops = {
504 .owner = THIS_MODULE,
505 .read = skel_read,
506 .write = skel_write,
507 .open = skel_open,
508 .release = skel_release,
509 .flush = skel_flush,
510 .llseek = noop_llseek,
511};
512
513/*
514 * usb class driver info in order to get a minor number from the usb core,
515 * and to have the device registered with the driver core
516 */
517static struct usb_class_driver skel_class = {
518 .name = "skel%d",
519 .fops = &skel_fops,
520 .minor_base = USB_SKEL_MINOR_BASE,
521};
522
523static int skel_probe(struct usb_interface *interface,
524 const struct usb_device_id *id)
525{
526 struct usb_skel *dev;
527 struct usb_host_interface *iface_desc;
528 struct usb_endpoint_descriptor *endpoint;
529 size_t buffer_size;
530 int i;
531 int retval = -ENOMEM;
532
533 /* allocate memory for our device state and initialize it */
534 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
535 if (!dev) {
536 err("Out of memory");
537 goto error;
538 }
539 kref_init(&dev->kref);
540 sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
541 mutex_init(&dev->io_mutex);
542 spin_lock_init(&dev->err_lock);
543 init_usb_anchor(&dev->submitted);
544 init_completion(&dev->bulk_in_completion);
545
546 dev->udev = usb_get_dev(interface_to_usbdev(interface));
547 dev->interface = interface;
548
549 /* set up the endpoint information */
550 /* use only the first bulk-in and bulk-out endpoints */
551 iface_desc = interface->cur_altsetting;
552 for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
553 endpoint = &iface_desc->endpoint[i].desc;
554
555 if (!dev->bulk_in_endpointAddr &&
556 usb_endpoint_is_bulk_in(endpoint)) {
557 /* we found a bulk in endpoint */
558 buffer_size = le16_to_cpu(endpoint->wMaxPacketSize);
559 dev->bulk_in_size = buffer_size;
560 dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
561 dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
562 if (!dev->bulk_in_buffer) {
563 err("Could not allocate bulk_in_buffer");
564 goto error;
565 }
566 dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL);
567 if (!dev->bulk_in_urb) {
568 err("Could not allocate bulk_in_urb");
569 goto error;
570 }
571 }
572
573 if (!dev->bulk_out_endpointAddr &&
574 usb_endpoint_is_bulk_out(endpoint)) {
575 /* we found a bulk out endpoint */
576 dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
577 }
578 }
579 if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
580 err("Could not find both bulk-in and bulk-out endpoints");
581 goto error;
582 }
583
584 /* save our data pointer in this interface device */
585 usb_set_intfdata(interface, dev);
586
587 /* we can register the device now, as it is ready */
588 retval = usb_register_dev(interface, &skel_class);
589 if (retval) {
590 /* something prevented us from registering this driver */
591 err("Not able to get a minor for this device.");
592 usb_set_intfdata(interface, NULL);
593 goto error;
594 }
595
596 /* let the user know what node this device is now attached to */
597 dev_info(&interface->dev,
598 "USB Skeleton device now attached to USBSkel-%d",
599 interface->minor);
600 return 0;
601
602error:
603 if (dev)
604 /* this frees allocated memory */
605 kref_put(&dev->kref, skel_delete);
606 return retval;
607}
608
609static void skel_disconnect(struct usb_interface *interface)
610{
611 struct usb_skel *dev;
612 int minor = interface->minor;
613
614 dev = usb_get_intfdata(interface);
615 usb_set_intfdata(interface, NULL);
616
617 /* give back our minor */
618 usb_deregister_dev(interface, &skel_class);
619
620 /* prevent more I/O from starting */
621 mutex_lock(&dev->io_mutex);
622 dev->interface = NULL;
623 mutex_unlock(&dev->io_mutex);
624
625 usb_kill_anchored_urbs(&dev->submitted);
626
627 /* decrement our usage count */
628 kref_put(&dev->kref, skel_delete);
629
630 dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor);
631}
632
633static void skel_draw_down(struct usb_skel *dev)
634{
635 int time;
636
637 time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
638 if (!time)
639 usb_kill_anchored_urbs(&dev->submitted);
640 usb_kill_urb(dev->bulk_in_urb);
641}
642
643static int skel_suspend(struct usb_interface *intf, pm_message_t message)
644{
645 struct usb_skel *dev = usb_get_intfdata(intf);
646
647 if (!dev)
648 return 0;
649 skel_draw_down(dev);
650 return 0;
651}
652
653static int skel_resume(struct usb_interface *intf)
654{
655 return 0;
656}
657
658static int skel_pre_reset(struct usb_interface *intf)
659{
660 struct usb_skel *dev = usb_get_intfdata(intf);
661
662 mutex_lock(&dev->io_mutex);
663 skel_draw_down(dev);
664
665 return 0;
666}
667
668static int skel_post_reset(struct usb_interface *intf)
669{
670 struct usb_skel *dev = usb_get_intfdata(intf);
671
672 /* we are sure no URBs are active - no locking needed */
673 dev->errors = -EPIPE;
674 mutex_unlock(&dev->io_mutex);
675
676 return 0;
677}
678
679static struct usb_driver skel_driver = {
680 .name = "skeleton",
681 .probe = skel_probe,
682 .disconnect = skel_disconnect,
683 .suspend = skel_suspend,
684 .resume = skel_resume,
685 .pre_reset = skel_pre_reset,
686 .post_reset = skel_post_reset,
687 .id_table = skel_table,
688 .supports_autosuspend = 1,
689};
690
691static int __init usb_skel_init(void)
692{
693 int result;
694
695 /* register this driver with the USB subsystem */
696 result = usb_register(&skel_driver);
697 if (result)
698 err("usb_register failed. Error number %d", result);
699
700 return result;
701}
702
703static void __exit usb_skel_exit(void)
704{
705 /* deregister this driver with the USB subsystem */
706 usb_deregister(&skel_driver);
707}
708
709module_init(usb_skel_init);
710module_exit(usb_skel_exit);
711
712MODULE_LICENSE("GPL");
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * USB Skeleton driver - 2.2
4 *
5 * Copyright (C) 2001-2004 Greg Kroah-Hartman (greg@kroah.com)
6 *
7 * This driver is based on the 2.6.3 version of drivers/usb/usb-skeleton.c
8 * but has been rewritten to be easier to read and use.
9 */
10
11#include <linux/kernel.h>
12#include <linux/errno.h>
13#include <linux/slab.h>
14#include <linux/module.h>
15#include <linux/kref.h>
16#include <linux/uaccess.h>
17#include <linux/usb.h>
18#include <linux/mutex.h>
19
20
21/* Define these values to match your devices */
22#define USB_SKEL_VENDOR_ID 0xfff0
23#define USB_SKEL_PRODUCT_ID 0xfff0
24
25/* table of devices that work with this driver */
26static const struct usb_device_id skel_table[] = {
27 { USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) },
28 { } /* Terminating entry */
29};
30MODULE_DEVICE_TABLE(usb, skel_table);
31
32
33/* Get a minor range for your devices from the usb maintainer */
34#define USB_SKEL_MINOR_BASE 192
35
36/* our private defines. if this grows any larger, use your own .h file */
37#define MAX_TRANSFER (PAGE_SIZE - 512)
38/* MAX_TRANSFER is chosen so that the VM is not stressed by
39 allocations > PAGE_SIZE and the number of packets in a page
40 is an integer 512 is the largest possible packet on EHCI */
41#define WRITES_IN_FLIGHT 8
42/* arbitrarily chosen */
43
44/* Structure to hold all of our device specific stuff */
45struct usb_skel {
46 struct usb_device *udev; /* the usb device for this device */
47 struct usb_interface *interface; /* the interface for this device */
48 struct semaphore limit_sem; /* limiting the number of writes in progress */
49 struct usb_anchor submitted; /* in case we need to retract our submissions */
50 struct urb *bulk_in_urb; /* the urb to read data with */
51 unsigned char *bulk_in_buffer; /* the buffer to receive data */
52 size_t bulk_in_size; /* the size of the receive buffer */
53 size_t bulk_in_filled; /* number of bytes in the buffer */
54 size_t bulk_in_copied; /* already copied to user space */
55 __u8 bulk_in_endpointAddr; /* the address of the bulk in endpoint */
56 __u8 bulk_out_endpointAddr; /* the address of the bulk out endpoint */
57 int errors; /* the last request tanked */
58 bool ongoing_read; /* a read is going on */
59 spinlock_t err_lock; /* lock for errors */
60 struct kref kref;
61 struct mutex io_mutex; /* synchronize I/O with disconnect */
62 wait_queue_head_t bulk_in_wait; /* to wait for an ongoing read */
63};
64#define to_skel_dev(d) container_of(d, struct usb_skel, kref)
65
66static struct usb_driver skel_driver;
67static void skel_draw_down(struct usb_skel *dev);
68
69static void skel_delete(struct kref *kref)
70{
71 struct usb_skel *dev = to_skel_dev(kref);
72
73 usb_free_urb(dev->bulk_in_urb);
74 usb_put_dev(dev->udev);
75 kfree(dev->bulk_in_buffer);
76 kfree(dev);
77}
78
79static int skel_open(struct inode *inode, struct file *file)
80{
81 struct usb_skel *dev;
82 struct usb_interface *interface;
83 int subminor;
84 int retval = 0;
85
86 subminor = iminor(inode);
87
88 interface = usb_find_interface(&skel_driver, subminor);
89 if (!interface) {
90 pr_err("%s - error, can't find device for minor %d\n",
91 __func__, subminor);
92 retval = -ENODEV;
93 goto exit;
94 }
95
96 dev = usb_get_intfdata(interface);
97 if (!dev) {
98 retval = -ENODEV;
99 goto exit;
100 }
101
102 retval = usb_autopm_get_interface(interface);
103 if (retval)
104 goto exit;
105
106 /* increment our usage count for the device */
107 kref_get(&dev->kref);
108
109 /* save our object in the file's private structure */
110 file->private_data = dev;
111
112exit:
113 return retval;
114}
115
116static int skel_release(struct inode *inode, struct file *file)
117{
118 struct usb_skel *dev;
119
120 dev = file->private_data;
121 if (dev == NULL)
122 return -ENODEV;
123
124 /* allow the device to be autosuspended */
125 mutex_lock(&dev->io_mutex);
126 if (dev->interface)
127 usb_autopm_put_interface(dev->interface);
128 mutex_unlock(&dev->io_mutex);
129
130 /* decrement the count on our device */
131 kref_put(&dev->kref, skel_delete);
132 return 0;
133}
134
135static int skel_flush(struct file *file, fl_owner_t id)
136{
137 struct usb_skel *dev;
138 int res;
139
140 dev = file->private_data;
141 if (dev == NULL)
142 return -ENODEV;
143
144 /* wait for io to stop */
145 mutex_lock(&dev->io_mutex);
146 skel_draw_down(dev);
147
148 /* read out errors, leave subsequent opens a clean slate */
149 spin_lock_irq(&dev->err_lock);
150 res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0;
151 dev->errors = 0;
152 spin_unlock_irq(&dev->err_lock);
153
154 mutex_unlock(&dev->io_mutex);
155
156 return res;
157}
158
159static void skel_read_bulk_callback(struct urb *urb)
160{
161 struct usb_skel *dev;
162
163 dev = urb->context;
164
165 spin_lock(&dev->err_lock);
166 /* sync/async unlink faults aren't errors */
167 if (urb->status) {
168 if (!(urb->status == -ENOENT ||
169 urb->status == -ECONNRESET ||
170 urb->status == -ESHUTDOWN))
171 dev_err(&dev->interface->dev,
172 "%s - nonzero write bulk status received: %d\n",
173 __func__, urb->status);
174
175 dev->errors = urb->status;
176 } else {
177 dev->bulk_in_filled = urb->actual_length;
178 }
179 dev->ongoing_read = 0;
180 spin_unlock(&dev->err_lock);
181
182 wake_up_interruptible(&dev->bulk_in_wait);
183}
184
185static int skel_do_read_io(struct usb_skel *dev, size_t count)
186{
187 int rv;
188
189 /* prepare a read */
190 usb_fill_bulk_urb(dev->bulk_in_urb,
191 dev->udev,
192 usb_rcvbulkpipe(dev->udev,
193 dev->bulk_in_endpointAddr),
194 dev->bulk_in_buffer,
195 min(dev->bulk_in_size, count),
196 skel_read_bulk_callback,
197 dev);
198 /* tell everybody to leave the URB alone */
199 spin_lock_irq(&dev->err_lock);
200 dev->ongoing_read = 1;
201 spin_unlock_irq(&dev->err_lock);
202
203 /* submit bulk in urb, which means no data to deliver */
204 dev->bulk_in_filled = 0;
205 dev->bulk_in_copied = 0;
206
207 /* do it */
208 rv = usb_submit_urb(dev->bulk_in_urb, GFP_KERNEL);
209 if (rv < 0) {
210 dev_err(&dev->interface->dev,
211 "%s - failed submitting read urb, error %d\n",
212 __func__, rv);
213 rv = (rv == -ENOMEM) ? rv : -EIO;
214 spin_lock_irq(&dev->err_lock);
215 dev->ongoing_read = 0;
216 spin_unlock_irq(&dev->err_lock);
217 }
218
219 return rv;
220}
221
222static ssize_t skel_read(struct file *file, char *buffer, size_t count,
223 loff_t *ppos)
224{
225 struct usb_skel *dev;
226 int rv;
227 bool ongoing_io;
228
229 dev = file->private_data;
230
231 /* if we cannot read at all, return EOF */
232 if (!dev->bulk_in_urb || !count)
233 return 0;
234
235 /* no concurrent readers */
236 rv = mutex_lock_interruptible(&dev->io_mutex);
237 if (rv < 0)
238 return rv;
239
240 if (!dev->interface) { /* disconnect() was called */
241 rv = -ENODEV;
242 goto exit;
243 }
244
245 /* if IO is under way, we must not touch things */
246retry:
247 spin_lock_irq(&dev->err_lock);
248 ongoing_io = dev->ongoing_read;
249 spin_unlock_irq(&dev->err_lock);
250
251 if (ongoing_io) {
252 /* nonblocking IO shall not wait */
253 if (file->f_flags & O_NONBLOCK) {
254 rv = -EAGAIN;
255 goto exit;
256 }
257 /*
258 * IO may take forever
259 * hence wait in an interruptible state
260 */
261 rv = wait_event_interruptible(dev->bulk_in_wait, (!dev->ongoing_read));
262 if (rv < 0)
263 goto exit;
264 }
265
266 /* errors must be reported */
267 rv = dev->errors;
268 if (rv < 0) {
269 /* any error is reported once */
270 dev->errors = 0;
271 /* to preserve notifications about reset */
272 rv = (rv == -EPIPE) ? rv : -EIO;
273 /* report it */
274 goto exit;
275 }
276
277 /*
278 * if the buffer is filled we may satisfy the read
279 * else we need to start IO
280 */
281
282 if (dev->bulk_in_filled) {
283 /* we had read data */
284 size_t available = dev->bulk_in_filled - dev->bulk_in_copied;
285 size_t chunk = min(available, count);
286
287 if (!available) {
288 /*
289 * all data has been used
290 * actual IO needs to be done
291 */
292 rv = skel_do_read_io(dev, count);
293 if (rv < 0)
294 goto exit;
295 else
296 goto retry;
297 }
298 /*
299 * data is available
300 * chunk tells us how much shall be copied
301 */
302
303 if (copy_to_user(buffer,
304 dev->bulk_in_buffer + dev->bulk_in_copied,
305 chunk))
306 rv = -EFAULT;
307 else
308 rv = chunk;
309
310 dev->bulk_in_copied += chunk;
311
312 /*
313 * if we are asked for more than we have,
314 * we start IO but don't wait
315 */
316 if (available < count)
317 skel_do_read_io(dev, count - chunk);
318 } else {
319 /* no data in the buffer */
320 rv = skel_do_read_io(dev, count);
321 if (rv < 0)
322 goto exit;
323 else
324 goto retry;
325 }
326exit:
327 mutex_unlock(&dev->io_mutex);
328 return rv;
329}
330
331static void skel_write_bulk_callback(struct urb *urb)
332{
333 struct usb_skel *dev;
334
335 dev = urb->context;
336
337 /* sync/async unlink faults aren't errors */
338 if (urb->status) {
339 if (!(urb->status == -ENOENT ||
340 urb->status == -ECONNRESET ||
341 urb->status == -ESHUTDOWN))
342 dev_err(&dev->interface->dev,
343 "%s - nonzero write bulk status received: %d\n",
344 __func__, urb->status);
345
346 spin_lock(&dev->err_lock);
347 dev->errors = urb->status;
348 spin_unlock(&dev->err_lock);
349 }
350
351 /* free up our allocated buffer */
352 usb_free_coherent(urb->dev, urb->transfer_buffer_length,
353 urb->transfer_buffer, urb->transfer_dma);
354 up(&dev->limit_sem);
355}
356
357static ssize_t skel_write(struct file *file, const char *user_buffer,
358 size_t count, loff_t *ppos)
359{
360 struct usb_skel *dev;
361 int retval = 0;
362 struct urb *urb = NULL;
363 char *buf = NULL;
364 size_t writesize = min(count, (size_t)MAX_TRANSFER);
365
366 dev = file->private_data;
367
368 /* verify that we actually have some data to write */
369 if (count == 0)
370 goto exit;
371
372 /*
373 * limit the number of URBs in flight to stop a user from using up all
374 * RAM
375 */
376 if (!(file->f_flags & O_NONBLOCK)) {
377 if (down_interruptible(&dev->limit_sem)) {
378 retval = -ERESTARTSYS;
379 goto exit;
380 }
381 } else {
382 if (down_trylock(&dev->limit_sem)) {
383 retval = -EAGAIN;
384 goto exit;
385 }
386 }
387
388 spin_lock_irq(&dev->err_lock);
389 retval = dev->errors;
390 if (retval < 0) {
391 /* any error is reported once */
392 dev->errors = 0;
393 /* to preserve notifications about reset */
394 retval = (retval == -EPIPE) ? retval : -EIO;
395 }
396 spin_unlock_irq(&dev->err_lock);
397 if (retval < 0)
398 goto error;
399
400 /* create a urb, and a buffer for it, and copy the data to the urb */
401 urb = usb_alloc_urb(0, GFP_KERNEL);
402 if (!urb) {
403 retval = -ENOMEM;
404 goto error;
405 }
406
407 buf = usb_alloc_coherent(dev->udev, writesize, GFP_KERNEL,
408 &urb->transfer_dma);
409 if (!buf) {
410 retval = -ENOMEM;
411 goto error;
412 }
413
414 if (copy_from_user(buf, user_buffer, writesize)) {
415 retval = -EFAULT;
416 goto error;
417 }
418
419 /* this lock makes sure we don't submit URBs to gone devices */
420 mutex_lock(&dev->io_mutex);
421 if (!dev->interface) { /* disconnect() was called */
422 mutex_unlock(&dev->io_mutex);
423 retval = -ENODEV;
424 goto error;
425 }
426
427 /* initialize the urb properly */
428 usb_fill_bulk_urb(urb, dev->udev,
429 usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
430 buf, writesize, skel_write_bulk_callback, dev);
431 urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
432 usb_anchor_urb(urb, &dev->submitted);
433
434 /* send the data out the bulk port */
435 retval = usb_submit_urb(urb, GFP_KERNEL);
436 mutex_unlock(&dev->io_mutex);
437 if (retval) {
438 dev_err(&dev->interface->dev,
439 "%s - failed submitting write urb, error %d\n",
440 __func__, retval);
441 goto error_unanchor;
442 }
443
444 /*
445 * release our reference to this urb, the USB core will eventually free
446 * it entirely
447 */
448 usb_free_urb(urb);
449
450
451 return writesize;
452
453error_unanchor:
454 usb_unanchor_urb(urb);
455error:
456 if (urb) {
457 usb_free_coherent(dev->udev, writesize, buf, urb->transfer_dma);
458 usb_free_urb(urb);
459 }
460 up(&dev->limit_sem);
461
462exit:
463 return retval;
464}
465
466static const struct file_operations skel_fops = {
467 .owner = THIS_MODULE,
468 .read = skel_read,
469 .write = skel_write,
470 .open = skel_open,
471 .release = skel_release,
472 .flush = skel_flush,
473 .llseek = noop_llseek,
474};
475
476/*
477 * usb class driver info in order to get a minor number from the usb core,
478 * and to have the device registered with the driver core
479 */
480static struct usb_class_driver skel_class = {
481 .name = "skel%d",
482 .fops = &skel_fops,
483 .minor_base = USB_SKEL_MINOR_BASE,
484};
485
486static int skel_probe(struct usb_interface *interface,
487 const struct usb_device_id *id)
488{
489 struct usb_skel *dev;
490 struct usb_endpoint_descriptor *bulk_in, *bulk_out;
491 int retval;
492
493 /* allocate memory for our device state and initialize it */
494 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
495 if (!dev)
496 return -ENOMEM;
497
498 kref_init(&dev->kref);
499 sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
500 mutex_init(&dev->io_mutex);
501 spin_lock_init(&dev->err_lock);
502 init_usb_anchor(&dev->submitted);
503 init_waitqueue_head(&dev->bulk_in_wait);
504
505 dev->udev = usb_get_dev(interface_to_usbdev(interface));
506 dev->interface = interface;
507
508 /* set up the endpoint information */
509 /* use only the first bulk-in and bulk-out endpoints */
510 retval = usb_find_common_endpoints(interface->cur_altsetting,
511 &bulk_in, &bulk_out, NULL, NULL);
512 if (retval) {
513 dev_err(&interface->dev,
514 "Could not find both bulk-in and bulk-out endpoints\n");
515 goto error;
516 }
517
518 dev->bulk_in_size = usb_endpoint_maxp(bulk_in);
519 dev->bulk_in_endpointAddr = bulk_in->bEndpointAddress;
520 dev->bulk_in_buffer = kmalloc(dev->bulk_in_size, GFP_KERNEL);
521 if (!dev->bulk_in_buffer) {
522 retval = -ENOMEM;
523 goto error;
524 }
525 dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL);
526 if (!dev->bulk_in_urb) {
527 retval = -ENOMEM;
528 goto error;
529 }
530
531 dev->bulk_out_endpointAddr = bulk_out->bEndpointAddress;
532
533 /* save our data pointer in this interface device */
534 usb_set_intfdata(interface, dev);
535
536 /* we can register the device now, as it is ready */
537 retval = usb_register_dev(interface, &skel_class);
538 if (retval) {
539 /* something prevented us from registering this driver */
540 dev_err(&interface->dev,
541 "Not able to get a minor for this device.\n");
542 usb_set_intfdata(interface, NULL);
543 goto error;
544 }
545
546 /* let the user know what node this device is now attached to */
547 dev_info(&interface->dev,
548 "USB Skeleton device now attached to USBSkel-%d",
549 interface->minor);
550 return 0;
551
552error:
553 /* this frees allocated memory */
554 kref_put(&dev->kref, skel_delete);
555
556 return retval;
557}
558
559static void skel_disconnect(struct usb_interface *interface)
560{
561 struct usb_skel *dev;
562 int minor = interface->minor;
563
564 dev = usb_get_intfdata(interface);
565 usb_set_intfdata(interface, NULL);
566
567 /* give back our minor */
568 usb_deregister_dev(interface, &skel_class);
569
570 /* prevent more I/O from starting */
571 mutex_lock(&dev->io_mutex);
572 dev->interface = NULL;
573 mutex_unlock(&dev->io_mutex);
574
575 usb_kill_anchored_urbs(&dev->submitted);
576
577 /* decrement our usage count */
578 kref_put(&dev->kref, skel_delete);
579
580 dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor);
581}
582
583static void skel_draw_down(struct usb_skel *dev)
584{
585 int time;
586
587 time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
588 if (!time)
589 usb_kill_anchored_urbs(&dev->submitted);
590 usb_kill_urb(dev->bulk_in_urb);
591}
592
593static int skel_suspend(struct usb_interface *intf, pm_message_t message)
594{
595 struct usb_skel *dev = usb_get_intfdata(intf);
596
597 if (!dev)
598 return 0;
599 skel_draw_down(dev);
600 return 0;
601}
602
603static int skel_resume(struct usb_interface *intf)
604{
605 return 0;
606}
607
608static int skel_pre_reset(struct usb_interface *intf)
609{
610 struct usb_skel *dev = usb_get_intfdata(intf);
611
612 mutex_lock(&dev->io_mutex);
613 skel_draw_down(dev);
614
615 return 0;
616}
617
618static int skel_post_reset(struct usb_interface *intf)
619{
620 struct usb_skel *dev = usb_get_intfdata(intf);
621
622 /* we are sure no URBs are active - no locking needed */
623 dev->errors = -EPIPE;
624 mutex_unlock(&dev->io_mutex);
625
626 return 0;
627}
628
629static struct usb_driver skel_driver = {
630 .name = "skeleton",
631 .probe = skel_probe,
632 .disconnect = skel_disconnect,
633 .suspend = skel_suspend,
634 .resume = skel_resume,
635 .pre_reset = skel_pre_reset,
636 .post_reset = skel_post_reset,
637 .id_table = skel_table,
638 .supports_autosuspend = 1,
639};
640
641module_usb_driver(skel_driver);
642
643MODULE_LICENSE("GPL v2");