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