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 */
31 static const struct usb_device_id skel_table[] = {
32 { USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) },
33 { } /* Terminating entry */
34 };
35 MODULE_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 */
50 struct 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 bool ongoing_read; /* a read is going on */
64 bool processed_urb; /* indicates we haven't processed the urb */
65 spinlock_t err_lock; /* lock for errors */
66 struct kref kref;
67 struct mutex io_mutex; /* synchronize I/O with disconnect */
68 struct completion bulk_in_completion; /* to wait for an ongoing read */
69 };
70 #define to_skel_dev(d) container_of(d, struct usb_skel, kref)
71
72 static struct usb_driver skel_driver;
73 static void skel_draw_down(struct usb_skel *dev);
74
skel_delete(struct kref * kref)75 static 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
skel_open(struct inode * inode,struct file * file)85 static 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 err("%s - error, can't find device for minor %d",
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 /* increment our usage count for the device */
109 kref_get(&dev->kref);
110
111 /* lock the device to allow correctly handling errors
112 * in resumption */
113 mutex_lock(&dev->io_mutex);
114
115 retval = usb_autopm_get_interface(interface);
116 if (retval)
117 goto out_err;
118
119 /* save our object in the file's private structure */
120 file->private_data = dev;
121 mutex_unlock(&dev->io_mutex);
122
123 exit:
124 return retval;
125 }
126
skel_release(struct inode * inode,struct file * file)127 static 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 /* allow the device to be autosuspended */
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 /* decrement the count on our device */
142 kref_put(&dev->kref, skel_delete);
143 return 0;
144 }
145
skel_flush(struct file * file,fl_owner_t id)146 static 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 /* wait for io to stop */
156 mutex_lock(&dev->io_mutex);
157 skel_draw_down(dev);
158
159 /* read out errors, leave subsequent opens a clean slate */
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
skel_read_bulk_callback(struct urb * urb)170 static 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 /* sync/async unlink faults aren't errors */
178 if (urb->status) {
179 if (!(urb->status == -ENOENT ||
180 urb->status == -ECONNRESET ||
181 urb->status == -ESHUTDOWN))
182 err("%s - nonzero write bulk status received: %d",
183 __func__, urb->status);
184
185 dev->errors = urb->status;
186 } else {
187 dev->bulk_in_filled = urb->actual_length;
188 }
189 dev->ongoing_read = 0;
190 spin_unlock(&dev->err_lock);
191
192 complete(&dev->bulk_in_completion);
193 }
194
skel_do_read_io(struct usb_skel * dev,size_t count)195 static int skel_do_read_io(struct usb_skel *dev, size_t count)
196 {
197 int rv;
198
199 /* prepare a read */
200 usb_fill_bulk_urb(dev->bulk_in_urb,
201 dev->udev,
202 usb_rcvbulkpipe(dev->udev,
203 dev->bulk_in_endpointAddr),
204 dev->bulk_in_buffer,
205 min(dev->bulk_in_size, count),
206 skel_read_bulk_callback,
207 dev);
208 /* tell everybody to leave the URB alone */
209 spin_lock_irq(&dev->err_lock);
210 dev->ongoing_read = 1;
211 spin_unlock_irq(&dev->err_lock);
212
213 /* do it */
214 rv = usb_submit_urb(dev->bulk_in_urb, GFP_KERNEL);
215 if (rv < 0) {
216 err("%s - failed submitting read urb, error %d",
217 __func__, rv);
218 dev->bulk_in_filled = 0;
219 rv = (rv == -ENOMEM) ? rv : -EIO;
220 spin_lock_irq(&dev->err_lock);
221 dev->ongoing_read = 0;
222 spin_unlock_irq(&dev->err_lock);
223 }
224
225 return rv;
226 }
227
skel_read(struct file * file,char * buffer,size_t count,loff_t * ppos)228 static ssize_t skel_read(struct file *file, char *buffer, size_t count,
229 loff_t *ppos)
230 {
231 struct usb_skel *dev;
232 int rv;
233 bool ongoing_io;
234
235 dev = file->private_data;
236
237 /* if we cannot read at all, return EOF */
238 if (!dev->bulk_in_urb || !count)
239 return 0;
240
241 /* no concurrent readers */
242 rv = mutex_lock_interruptible(&dev->io_mutex);
243 if (rv < 0)
244 return rv;
245
246 if (!dev->interface) { /* disconnect() was called */
247 rv = -ENODEV;
248 goto exit;
249 }
250
251 /* if IO is under way, we must not touch things */
252 retry:
253 spin_lock_irq(&dev->err_lock);
254 ongoing_io = dev->ongoing_read;
255 spin_unlock_irq(&dev->err_lock);
256
257 if (ongoing_io) {
258 /* nonblocking IO shall not wait */
259 if (file->f_flags & O_NONBLOCK) {
260 rv = -EAGAIN;
261 goto exit;
262 }
263 /*
264 * IO may take forever
265 * hence wait in an interruptible state
266 */
267 rv = wait_for_completion_interruptible(&dev->bulk_in_completion);
268 if (rv < 0)
269 goto exit;
270 /*
271 * by waiting we also semiprocessed the urb
272 * we must finish now
273 */
274 dev->bulk_in_copied = 0;
275 dev->processed_urb = 1;
276 }
277
278 if (!dev->processed_urb) {
279 /*
280 * the URB hasn't been processed
281 * do it now
282 */
283 wait_for_completion(&dev->bulk_in_completion);
284 dev->bulk_in_copied = 0;
285 dev->processed_urb = 1;
286 }
287
288 /* errors must be reported */
289 rv = dev->errors;
290 if (rv < 0) {
291 /* any error is reported once */
292 dev->errors = 0;
293 /* to preserve notifications about reset */
294 rv = (rv == -EPIPE) ? rv : -EIO;
295 /* no data to deliver */
296 dev->bulk_in_filled = 0;
297 /* report it */
298 goto exit;
299 }
300
301 /*
302 * if the buffer is filled we may satisfy the read
303 * else we need to start IO
304 */
305
306 if (dev->bulk_in_filled) {
307 /* we had read data */
308 size_t available = dev->bulk_in_filled - dev->bulk_in_copied;
309 size_t chunk = min(available, count);
310
311 if (!available) {
312 /*
313 * all data has been used
314 * actual IO needs to be done
315 */
316 rv = skel_do_read_io(dev, count);
317 if (rv < 0)
318 goto exit;
319 else
320 goto retry;
321 }
322 /*
323 * data is available
324 * chunk tells us how much shall be copied
325 */
326
327 if (copy_to_user(buffer,
328 dev->bulk_in_buffer + dev->bulk_in_copied,
329 chunk))
330 rv = -EFAULT;
331 else
332 rv = chunk;
333
334 dev->bulk_in_copied += chunk;
335
336 /*
337 * if we are asked for more than we have,
338 * we start IO but don't wait
339 */
340 if (available < count)
341 skel_do_read_io(dev, count - chunk);
342 } else {
343 /* no data in the buffer */
344 rv = skel_do_read_io(dev, count);
345 if (rv < 0)
346 goto exit;
347 else if (!(file->f_flags & O_NONBLOCK))
348 goto retry;
349 rv = -EAGAIN;
350 }
351 exit:
352 mutex_unlock(&dev->io_mutex);
353 return rv;
354 }
355
skel_write_bulk_callback(struct urb * urb)356 static void skel_write_bulk_callback(struct urb *urb)
357 {
358 struct usb_skel *dev;
359
360 dev = urb->context;
361
362 /* sync/async unlink faults aren't errors */
363 if (urb->status) {
364 if (!(urb->status == -ENOENT ||
365 urb->status == -ECONNRESET ||
366 urb->status == -ESHUTDOWN))
367 err("%s - nonzero write bulk status received: %d",
368 __func__, urb->status);
369
370 spin_lock(&dev->err_lock);
371 dev->errors = urb->status;
372 spin_unlock(&dev->err_lock);
373 }
374
375 /* free up our allocated buffer */
376 usb_free_coherent(urb->dev, urb->transfer_buffer_length,
377 urb->transfer_buffer, urb->transfer_dma);
378 up(&dev->limit_sem);
379 }
380
skel_write(struct file * file,const char * user_buffer,size_t count,loff_t * ppos)381 static ssize_t skel_write(struct file *file, const char *user_buffer,
382 size_t count, loff_t *ppos)
383 {
384 struct usb_skel *dev;
385 int retval = 0;
386 struct urb *urb = NULL;
387 char *buf = NULL;
388 size_t writesize = min(count, (size_t)MAX_TRANSFER);
389
390 dev = file->private_data;
391
392 /* verify that we actually have some data to write */
393 if (count == 0)
394 goto exit;
395
396 /*
397 * limit the number of URBs in flight to stop a user from using up all
398 * RAM
399 */
400 if (!(file->f_flags & O_NONBLOCK)) {
401 if (down_interruptible(&dev->limit_sem)) {
402 retval = -ERESTARTSYS;
403 goto exit;
404 }
405 } else {
406 if (down_trylock(&dev->limit_sem)) {
407 retval = -EAGAIN;
408 goto exit;
409 }
410 }
411
412 spin_lock_irq(&dev->err_lock);
413 retval = dev->errors;
414 if (retval < 0) {
415 /* any error is reported once */
416 dev->errors = 0;
417 /* to preserve notifications about reset */
418 retval = (retval == -EPIPE) ? retval : -EIO;
419 }
420 spin_unlock_irq(&dev->err_lock);
421 if (retval < 0)
422 goto error;
423
424 /* create a urb, and a buffer for it, and copy the data to the urb */
425 urb = usb_alloc_urb(0, GFP_KERNEL);
426 if (!urb) {
427 retval = -ENOMEM;
428 goto error;
429 }
430
431 buf = usb_alloc_coherent(dev->udev, writesize, GFP_KERNEL,
432 &urb->transfer_dma);
433 if (!buf) {
434 retval = -ENOMEM;
435 goto error;
436 }
437
438 if (copy_from_user(buf, user_buffer, writesize)) {
439 retval = -EFAULT;
440 goto error;
441 }
442
443 /* this lock makes sure we don't submit URBs to gone devices */
444 mutex_lock(&dev->io_mutex);
445 if (!dev->interface) { /* disconnect() was called */
446 mutex_unlock(&dev->io_mutex);
447 retval = -ENODEV;
448 goto error;
449 }
450
451 /* initialize the urb properly */
452 usb_fill_bulk_urb(urb, dev->udev,
453 usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
454 buf, writesize, skel_write_bulk_callback, dev);
455 urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
456 usb_anchor_urb(urb, &dev->submitted);
457
458 /* send the data out the bulk port */
459 retval = usb_submit_urb(urb, GFP_KERNEL);
460 mutex_unlock(&dev->io_mutex);
461 if (retval) {
462 err("%s - failed submitting write urb, error %d", __func__,
463 retval);
464 goto error_unanchor;
465 }
466
467 /*
468 * release our reference to this urb, the USB core will eventually free
469 * it entirely
470 */
471 usb_free_urb(urb);
472
473
474 return writesize;
475
476 error_unanchor:
477 usb_unanchor_urb(urb);
478 error:
479 if (urb) {
480 usb_free_coherent(dev->udev, writesize, buf, urb->transfer_dma);
481 usb_free_urb(urb);
482 }
483 up(&dev->limit_sem);
484
485 exit:
486 return retval;
487 }
488
489 static const struct file_operations skel_fops = {
490 .owner = THIS_MODULE,
491 .read = skel_read,
492 .write = skel_write,
493 .open = skel_open,
494 .release = skel_release,
495 .flush = skel_flush,
496 .llseek = noop_llseek,
497 };
498
499 /*
500 * usb class driver info in order to get a minor number from the usb core,
501 * and to have the device registered with the driver core
502 */
503 static struct usb_class_driver skel_class = {
504 .name = "skel%d",
505 .fops = &skel_fops,
506 .minor_base = USB_SKEL_MINOR_BASE,
507 };
508
skel_probe(struct usb_interface * interface,const struct usb_device_id * id)509 static int skel_probe(struct usb_interface *interface,
510 const struct usb_device_id *id)
511 {
512 struct usb_skel *dev;
513 struct usb_host_interface *iface_desc;
514 struct usb_endpoint_descriptor *endpoint;
515 size_t buffer_size;
516 int i;
517 int retval = -ENOMEM;
518
519 /* allocate memory for our device state and initialize it */
520 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
521 if (!dev) {
522 err("Out of memory");
523 goto error;
524 }
525 kref_init(&dev->kref);
526 sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
527 mutex_init(&dev->io_mutex);
528 spin_lock_init(&dev->err_lock);
529 init_usb_anchor(&dev->submitted);
530 init_completion(&dev->bulk_in_completion);
531
532 dev->udev = usb_get_dev(interface_to_usbdev(interface));
533 dev->interface = interface;
534
535 /* set up the endpoint information */
536 /* use only the first bulk-in and bulk-out endpoints */
537 iface_desc = interface->cur_altsetting;
538 for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
539 endpoint = &iface_desc->endpoint[i].desc;
540
541 if (!dev->bulk_in_endpointAddr &&
542 usb_endpoint_is_bulk_in(endpoint)) {
543 /* we found a bulk in endpoint */
544 buffer_size = usb_endpoint_maxp(endpoint);
545 dev->bulk_in_size = buffer_size;
546 dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
547 dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
548 if (!dev->bulk_in_buffer) {
549 err("Could not allocate bulk_in_buffer");
550 goto error;
551 }
552 dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL);
553 if (!dev->bulk_in_urb) {
554 err("Could not allocate bulk_in_urb");
555 goto error;
556 }
557 }
558
559 if (!dev->bulk_out_endpointAddr &&
560 usb_endpoint_is_bulk_out(endpoint)) {
561 /* we found a bulk out endpoint */
562 dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
563 }
564 }
565 if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
566 err("Could not find both bulk-in and bulk-out endpoints");
567 goto error;
568 }
569
570 /* save our data pointer in this interface device */
571 usb_set_intfdata(interface, dev);
572
573 /* we can register the device now, as it is ready */
574 retval = usb_register_dev(interface, &skel_class);
575 if (retval) {
576 /* something prevented us from registering this driver */
577 err("Not able to get a minor for this device.");
578 usb_set_intfdata(interface, NULL);
579 goto error;
580 }
581
582 /* let the user know what node this device is now attached to */
583 dev_info(&interface->dev,
584 "USB Skeleton device now attached to USBSkel-%d",
585 interface->minor);
586 return 0;
587
588 error:
589 if (dev)
590 /* this frees allocated memory */
591 kref_put(&dev->kref, skel_delete);
592 return retval;
593 }
594
skel_disconnect(struct usb_interface * interface)595 static void skel_disconnect(struct usb_interface *interface)
596 {
597 struct usb_skel *dev;
598 int minor = interface->minor;
599
600 dev = usb_get_intfdata(interface);
601 usb_set_intfdata(interface, NULL);
602
603 /* give back our minor */
604 usb_deregister_dev(interface, &skel_class);
605
606 /* prevent more I/O from starting */
607 mutex_lock(&dev->io_mutex);
608 dev->interface = NULL;
609 mutex_unlock(&dev->io_mutex);
610
611 usb_kill_anchored_urbs(&dev->submitted);
612
613 /* decrement our usage count */
614 kref_put(&dev->kref, skel_delete);
615
616 dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor);
617 }
618
skel_draw_down(struct usb_skel * dev)619 static void skel_draw_down(struct usb_skel *dev)
620 {
621 int time;
622
623 time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
624 if (!time)
625 usb_kill_anchored_urbs(&dev->submitted);
626 usb_kill_urb(dev->bulk_in_urb);
627 }
628
skel_suspend(struct usb_interface * intf,pm_message_t message)629 static int skel_suspend(struct usb_interface *intf, pm_message_t message)
630 {
631 struct usb_skel *dev = usb_get_intfdata(intf);
632
633 if (!dev)
634 return 0;
635 skel_draw_down(dev);
636 return 0;
637 }
638
skel_resume(struct usb_interface * intf)639 static int skel_resume(struct usb_interface *intf)
640 {
641 return 0;
642 }
643
skel_pre_reset(struct usb_interface * intf)644 static int skel_pre_reset(struct usb_interface *intf)
645 {
646 struct usb_skel *dev = usb_get_intfdata(intf);
647
648 mutex_lock(&dev->io_mutex);
649 skel_draw_down(dev);
650
651 return 0;
652 }
653
skel_post_reset(struct usb_interface * intf)654 static int skel_post_reset(struct usb_interface *intf)
655 {
656 struct usb_skel *dev = usb_get_intfdata(intf);
657
658 /* we are sure no URBs are active - no locking needed */
659 dev->errors = -EPIPE;
660 mutex_unlock(&dev->io_mutex);
661
662 return 0;
663 }
664
665 static struct usb_driver skel_driver = {
666 .name = "skeleton",
667 .probe = skel_probe,
668 .disconnect = skel_disconnect,
669 .suspend = skel_suspend,
670 .resume = skel_resume,
671 .pre_reset = skel_pre_reset,
672 .post_reset = skel_post_reset,
673 .id_table = skel_table,
674 .supports_autosuspend = 1,
675 };
676
677 module_usb_driver(skel_driver);
678
679 MODULE_LICENSE("GPL");
680