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