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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/*
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 */
47struct 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
69static struct usb_driver skel_driver;
70static void skel_draw_down(struct usb_skel *dev);
71
72static void skel_delete(struct kref *kref)
73{
74 struct usb_skel *dev = to_skel_dev(kref);
75
76 usb_free_urb(dev->bulk_in_urb);
77 usb_put_intf(dev->interface);
78 usb_put_dev(dev->udev);
79 kfree(dev->bulk_in_buffer);
80 kfree(dev);
81}
82
83static 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(&skel_driver, 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(interface);
101 if (!dev) {
102 retval = -ENODEV;
103 goto exit;
104 }
105
106 retval = usb_autopm_get_interface(interface);
107 if (retval)
108 goto exit;
109
110 /* increment our usage count for the device */
111 kref_get(&dev->kref);
112
113 /* save our object in the file's private structure */
114 file->private_data = dev;
115
116exit:
117 return retval;
118}
119
120static 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(dev->interface);
130
131 /* decrement the count on our device */
132 kref_put(&dev->kref, skel_delete);
133 return 0;
134}
135
136static 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(&dev->err_lock);
151 res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0;
152 dev->errors = 0;
153 spin_unlock_irq(&dev->err_lock);
154
155 mutex_unlock(&dev->io_mutex);
156
157 return res;
158}
159
160static 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(&dev->err_lock, flags);
183
184 wake_up_interruptible(&dev->bulk_in_wait);
185}
186
187static 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(dev->bulk_in_urb,
193 dev->udev,
194 usb_rcvbulkpipe(dev->udev,
195 dev->bulk_in_endpointAddr),
196 dev->bulk_in_buffer,
197 min(dev->bulk_in_size, count),
198 skel_read_bulk_callback,
199 dev);
200 /* tell everybody to leave the URB alone */
201 spin_lock_irq(&dev->err_lock);
202 dev->ongoing_read = 1;
203 spin_unlock_irq(&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(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(&dev->err_lock);
217 dev->ongoing_read = 0;
218 spin_unlock_irq(&dev->err_lock);
219 }
220
221 return rv;
222}
223
224static 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 */
247retry:
248 spin_lock_irq(&dev->err_lock);
249 ongoing_io = dev->ongoing_read;
250 spin_unlock_irq(&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(buffer,
305 dev->bulk_in_buffer + dev->bulk_in_copied,
306 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 - 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 }
327exit:
328 mutex_unlock(&dev->io_mutex);
329 return rv;
330}
331
332static 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(&dev->err_lock, flags);
351 }
352
353 /* free up our allocated buffer */
354 usb_free_coherent(urb->dev, urb->transfer_buffer_length,
355 urb->transfer_buffer, urb->transfer_dma);
356 up(&dev->limit_sem);
357}
358
359static 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(count, (size_t)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(&dev->limit_sem)) {
380 retval = -ERESTARTSYS;
381 goto exit;
382 }
383 } else {
384 if (down_trylock(&dev->limit_sem)) {
385 retval = -EAGAIN;
386 goto exit;
387 }
388 }
389
390 spin_lock_irq(&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(&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(0, GFP_KERNEL);
404 if (!urb) {
405 retval = -ENOMEM;
406 goto error;
407 }
408
409 buf = usb_alloc_coherent(dev->udev, writesize, GFP_KERNEL,
410 &urb->transfer_dma);
411 if (!buf) {
412 retval = -ENOMEM;
413 goto error;
414 }
415
416 if (copy_from_user(buf, user_buffer, 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(&dev->io_mutex);
425 retval = -ENODEV;
426 goto error;
427 }
428
429 /* initialize the urb properly */
430 usb_fill_bulk_urb(urb, dev->udev,
431 usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
432 buf, writesize, skel_write_bulk_callback, dev);
433 urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
434 usb_anchor_urb(urb, &dev->submitted);
435
436 /* send the data out the bulk port */
437 retval = usb_submit_urb(urb, GFP_KERNEL);
438 mutex_unlock(&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
455error_unanchor:
456 usb_unanchor_urb(urb);
457error:
458 if (urb) {
459 usb_free_coherent(dev->udev, writesize, buf, urb->transfer_dma);
460 usb_free_urb(urb);
461 }
462 up(&dev->limit_sem);
463
464exit:
465 return retval;
466}
467
468static 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 */
482static struct usb_class_driver skel_class = {
483 .name = "skel%d",
484 .fops = &skel_fops,
485 .minor_base = USB_SKEL_MINOR_BASE,
486};
487
488static 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(sizeof(*dev), GFP_KERNEL);
497 if (!dev)
498 return -ENOMEM;
499
500 kref_init(&dev->kref);
501 sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
502 mutex_init(&dev->io_mutex);
503 spin_lock_init(&dev->err_lock);
504 init_usb_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(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(interface->cur_altsetting,
513 &bulk_in, &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(bulk_in);
521 dev->bulk_in_endpointAddr = bulk_in->bEndpointAddress;
522 dev->bulk_in_buffer = kmalloc(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(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(interface, dev);
537
538 /* we can register the device now, as it is ready */
539 retval = usb_register_dev(interface, &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(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
554error:
555 /* this frees allocated memory */
556 kref_put(&dev->kref, skel_delete);
557
558 return retval;
559}
560
561static void skel_disconnect(struct usb_interface *interface)
562{
563 struct usb_skel *dev;
564 int minor = interface->minor;
565
566 dev = usb_get_intfdata(interface);
567 usb_set_intfdata(interface, NULL);
568
569 /* give back our minor */
570 usb_deregister_dev(interface, &skel_class);
571
572 /* prevent more I/O from starting */
573 mutex_lock(&dev->io_mutex);
574 dev->disconnected = 1;
575 mutex_unlock(&dev->io_mutex);
576
577 usb_kill_urb(dev->bulk_in_urb);
578 usb_kill_anchored_urbs(&dev->submitted);
579
580 /* decrement our usage count */
581 kref_put(&dev->kref, skel_delete);
582
583 dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor);
584}
585
586static void skel_draw_down(struct usb_skel *dev)
587{
588 int time;
589
590 time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
591 if (!time)
592 usb_kill_anchored_urbs(&dev->submitted);
593 usb_kill_urb(dev->bulk_in_urb);
594}
595
596static int skel_suspend(struct usb_interface *intf, pm_message_t message)
597{
598 struct usb_skel *dev = usb_get_intfdata(intf);
599
600 if (!dev)
601 return 0;
602 skel_draw_down(dev);
603 return 0;
604}
605
606static int skel_resume(struct usb_interface *intf)
607{
608 return 0;
609}
610
611static int skel_pre_reset(struct usb_interface *intf)
612{
613 struct usb_skel *dev = usb_get_intfdata(intf);
614
615 mutex_lock(&dev->io_mutex);
616 skel_draw_down(dev);
617
618 return 0;
619}
620
621static int skel_post_reset(struct usb_interface *intf)
622{
623 struct usb_skel *dev = usb_get_intfdata(intf);
624
625 /* we are sure no URBs are active - no locking needed */
626 dev->errors = -EPIPE;
627 mutex_unlock(&dev->io_mutex);
628
629 return 0;
630}
631
632static struct usb_driver skel_driver = {
633 .name = "skeleton",
634 .probe = skel_probe,
635 .disconnect = skel_disconnect,
636 .suspend = skel_suspend,
637 .resume = skel_resume,
638 .pre_reset = skel_pre_reset,
639 .post_reset = skel_post_reset,
640 .id_table = skel_table,
641 .supports_autosuspend = 1,
642};
643
644module_usb_driver(skel_driver);
645
646MODULE_LICENSE("GPL v2");
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 */
30static const struct usb_device_id skel_table[] = {
31 { USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) },
32 { } /* Terminating entry */
33};
34MODULE_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 */
49struct 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 wait_queue_head_t bulk_in_wait; /* to wait for an ongoing read */
67};
68#define to_skel_dev(d) container_of(d, struct usb_skel, kref)
69
70static struct usb_driver skel_driver;
71static void skel_draw_down(struct usb_skel *dev);
72
73static void skel_delete(struct kref *kref)
74{
75 struct usb_skel *dev = to_skel_dev(kref);
76
77 usb_free_urb(dev->bulk_in_urb);
78 usb_put_dev(dev->udev);
79 kfree(dev->bulk_in_buffer);
80 kfree(dev);
81}
82
83static 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(&skel_driver, 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(interface);
101 if (!dev) {
102 retval = -ENODEV;
103 goto exit;
104 }
105
106 retval = usb_autopm_get_interface(interface);
107 if (retval)
108 goto exit;
109
110 /* increment our usage count for the device */
111 kref_get(&dev->kref);
112
113 /* save our object in the file's private structure */
114 file->private_data = dev;
115
116exit:
117 return retval;
118}
119
120static 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 mutex_lock(&dev->io_mutex);
130 if (dev->interface)
131 usb_autopm_put_interface(dev->interface);
132 mutex_unlock(&dev->io_mutex);
133
134 /* decrement the count on our device */
135 kref_put(&dev->kref, skel_delete);
136 return 0;
137}
138
139static int skel_flush(struct file *file, fl_owner_t id)
140{
141 struct usb_skel *dev;
142 int res;
143
144 dev = file->private_data;
145 if (dev == NULL)
146 return -ENODEV;
147
148 /* wait for io to stop */
149 mutex_lock(&dev->io_mutex);
150 skel_draw_down(dev);
151
152 /* read out errors, leave subsequent opens a clean slate */
153 spin_lock_irq(&dev->err_lock);
154 res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0;
155 dev->errors = 0;
156 spin_unlock_irq(&dev->err_lock);
157
158 mutex_unlock(&dev->io_mutex);
159
160 return res;
161}
162
163static void skel_read_bulk_callback(struct urb *urb)
164{
165 struct usb_skel *dev;
166
167 dev = urb->context;
168
169 spin_lock(&dev->err_lock);
170 /* sync/async unlink faults aren't errors */
171 if (urb->status) {
172 if (!(urb->status == -ENOENT ||
173 urb->status == -ECONNRESET ||
174 urb->status == -ESHUTDOWN))
175 dev_err(&dev->interface->dev,
176 "%s - nonzero write bulk status received: %d\n",
177 __func__, urb->status);
178
179 dev->errors = urb->status;
180 } else {
181 dev->bulk_in_filled = urb->actual_length;
182 }
183 dev->ongoing_read = 0;
184 spin_unlock(&dev->err_lock);
185
186 wake_up_interruptible(&dev->bulk_in_wait);
187}
188
189static int skel_do_read_io(struct usb_skel *dev, size_t count)
190{
191 int rv;
192
193 /* prepare a read */
194 usb_fill_bulk_urb(dev->bulk_in_urb,
195 dev->udev,
196 usb_rcvbulkpipe(dev->udev,
197 dev->bulk_in_endpointAddr),
198 dev->bulk_in_buffer,
199 min(dev->bulk_in_size, count),
200 skel_read_bulk_callback,
201 dev);
202 /* tell everybody to leave the URB alone */
203 spin_lock_irq(&dev->err_lock);
204 dev->ongoing_read = 1;
205 spin_unlock_irq(&dev->err_lock);
206
207 /* submit bulk in urb, which means no data to deliver */
208 dev->bulk_in_filled = 0;
209 dev->bulk_in_copied = 0;
210
211 /* do it */
212 rv = usb_submit_urb(dev->bulk_in_urb, GFP_KERNEL);
213 if (rv < 0) {
214 dev_err(&dev->interface->dev,
215 "%s - failed submitting read urb, error %d\n",
216 __func__, rv);
217 rv = (rv == -ENOMEM) ? rv : -EIO;
218 spin_lock_irq(&dev->err_lock);
219 dev->ongoing_read = 0;
220 spin_unlock_irq(&dev->err_lock);
221 }
222
223 return rv;
224}
225
226static ssize_t skel_read(struct file *file, char *buffer, size_t count,
227 loff_t *ppos)
228{
229 struct usb_skel *dev;
230 int rv;
231 bool ongoing_io;
232
233 dev = file->private_data;
234
235 /* if we cannot read at all, return EOF */
236 if (!dev->bulk_in_urb || !count)
237 return 0;
238
239 /* no concurrent readers */
240 rv = mutex_lock_interruptible(&dev->io_mutex);
241 if (rv < 0)
242 return rv;
243
244 if (!dev->interface) { /* disconnect() was called */
245 rv = -ENODEV;
246 goto exit;
247 }
248
249 /* if IO is under way, we must not touch things */
250retry:
251 spin_lock_irq(&dev->err_lock);
252 ongoing_io = dev->ongoing_read;
253 spin_unlock_irq(&dev->err_lock);
254
255 if (ongoing_io) {
256 /* nonblocking IO shall not wait */
257 if (file->f_flags & O_NONBLOCK) {
258 rv = -EAGAIN;
259 goto exit;
260 }
261 /*
262 * IO may take forever
263 * hence wait in an interruptible state
264 */
265 rv = wait_event_interruptible(dev->bulk_in_wait, (!dev->ongoing_read));
266 if (rv < 0)
267 goto exit;
268 }
269
270 /* errors must be reported */
271 rv = dev->errors;
272 if (rv < 0) {
273 /* any error is reported once */
274 dev->errors = 0;
275 /* to preserve notifications about reset */
276 rv = (rv == -EPIPE) ? rv : -EIO;
277 /* report it */
278 goto exit;
279 }
280
281 /*
282 * if the buffer is filled we may satisfy the read
283 * else we need to start IO
284 */
285
286 if (dev->bulk_in_filled) {
287 /* we had read data */
288 size_t available = dev->bulk_in_filled - dev->bulk_in_copied;
289 size_t chunk = min(available, count);
290
291 if (!available) {
292 /*
293 * all data has been used
294 * actual IO needs to be done
295 */
296 rv = skel_do_read_io(dev, count);
297 if (rv < 0)
298 goto exit;
299 else
300 goto retry;
301 }
302 /*
303 * data is available
304 * chunk tells us how much shall be copied
305 */
306
307 if (copy_to_user(buffer,
308 dev->bulk_in_buffer + dev->bulk_in_copied,
309 chunk))
310 rv = -EFAULT;
311 else
312 rv = chunk;
313
314 dev->bulk_in_copied += chunk;
315
316 /*
317 * if we are asked for more than we have,
318 * we start IO but don't wait
319 */
320 if (available < count)
321 skel_do_read_io(dev, count - chunk);
322 } else {
323 /* no data in the buffer */
324 rv = skel_do_read_io(dev, count);
325 if (rv < 0)
326 goto exit;
327 else
328 goto retry;
329 }
330exit:
331 mutex_unlock(&dev->io_mutex);
332 return rv;
333}
334
335static void skel_write_bulk_callback(struct urb *urb)
336{
337 struct usb_skel *dev;
338
339 dev = urb->context;
340
341 /* sync/async unlink faults aren't errors */
342 if (urb->status) {
343 if (!(urb->status == -ENOENT ||
344 urb->status == -ECONNRESET ||
345 urb->status == -ESHUTDOWN))
346 dev_err(&dev->interface->dev,
347 "%s - nonzero write bulk status received: %d\n",
348 __func__, urb->status);
349
350 spin_lock(&dev->err_lock);
351 dev->errors = urb->status;
352 spin_unlock(&dev->err_lock);
353 }
354
355 /* free up our allocated buffer */
356 usb_free_coherent(urb->dev, urb->transfer_buffer_length,
357 urb->transfer_buffer, urb->transfer_dma);
358 up(&dev->limit_sem);
359}
360
361static ssize_t skel_write(struct file *file, const char *user_buffer,
362 size_t count, loff_t *ppos)
363{
364 struct usb_skel *dev;
365 int retval = 0;
366 struct urb *urb = NULL;
367 char *buf = NULL;
368 size_t writesize = min(count, (size_t)MAX_TRANSFER);
369
370 dev = file->private_data;
371
372 /* verify that we actually have some data to write */
373 if (count == 0)
374 goto exit;
375
376 /*
377 * limit the number of URBs in flight to stop a user from using up all
378 * RAM
379 */
380 if (!(file->f_flags & O_NONBLOCK)) {
381 if (down_interruptible(&dev->limit_sem)) {
382 retval = -ERESTARTSYS;
383 goto exit;
384 }
385 } else {
386 if (down_trylock(&dev->limit_sem)) {
387 retval = -EAGAIN;
388 goto exit;
389 }
390 }
391
392 spin_lock_irq(&dev->err_lock);
393 retval = dev->errors;
394 if (retval < 0) {
395 /* any error is reported once */
396 dev->errors = 0;
397 /* to preserve notifications about reset */
398 retval = (retval == -EPIPE) ? retval : -EIO;
399 }
400 spin_unlock_irq(&dev->err_lock);
401 if (retval < 0)
402 goto error;
403
404 /* create a urb, and a buffer for it, and copy the data to the urb */
405 urb = usb_alloc_urb(0, GFP_KERNEL);
406 if (!urb) {
407 retval = -ENOMEM;
408 goto error;
409 }
410
411 buf = usb_alloc_coherent(dev->udev, writesize, GFP_KERNEL,
412 &urb->transfer_dma);
413 if (!buf) {
414 retval = -ENOMEM;
415 goto error;
416 }
417
418 if (copy_from_user(buf, user_buffer, writesize)) {
419 retval = -EFAULT;
420 goto error;
421 }
422
423 /* this lock makes sure we don't submit URBs to gone devices */
424 mutex_lock(&dev->io_mutex);
425 if (!dev->interface) { /* disconnect() was called */
426 mutex_unlock(&dev->io_mutex);
427 retval = -ENODEV;
428 goto error;
429 }
430
431 /* initialize the urb properly */
432 usb_fill_bulk_urb(urb, dev->udev,
433 usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
434 buf, writesize, skel_write_bulk_callback, dev);
435 urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
436 usb_anchor_urb(urb, &dev->submitted);
437
438 /* send the data out the bulk port */
439 retval = usb_submit_urb(urb, GFP_KERNEL);
440 mutex_unlock(&dev->io_mutex);
441 if (retval) {
442 dev_err(&dev->interface->dev,
443 "%s - failed submitting write urb, error %d\n",
444 __func__, retval);
445 goto error_unanchor;
446 }
447
448 /*
449 * release our reference to this urb, the USB core will eventually free
450 * it entirely
451 */
452 usb_free_urb(urb);
453
454
455 return writesize;
456
457error_unanchor:
458 usb_unanchor_urb(urb);
459error:
460 if (urb) {
461 usb_free_coherent(dev->udev, writesize, buf, urb->transfer_dma);
462 usb_free_urb(urb);
463 }
464 up(&dev->limit_sem);
465
466exit:
467 return retval;
468}
469
470static const struct file_operations skel_fops = {
471 .owner = THIS_MODULE,
472 .read = skel_read,
473 .write = skel_write,
474 .open = skel_open,
475 .release = skel_release,
476 .flush = skel_flush,
477 .llseek = noop_llseek,
478};
479
480/*
481 * usb class driver info in order to get a minor number from the usb core,
482 * and to have the device registered with the driver core
483 */
484static struct usb_class_driver skel_class = {
485 .name = "skel%d",
486 .fops = &skel_fops,
487 .minor_base = USB_SKEL_MINOR_BASE,
488};
489
490static int skel_probe(struct usb_interface *interface,
491 const struct usb_device_id *id)
492{
493 struct usb_skel *dev;
494 struct usb_host_interface *iface_desc;
495 struct usb_endpoint_descriptor *endpoint;
496 size_t buffer_size;
497 int i;
498 int retval = -ENOMEM;
499
500 /* allocate memory for our device state and initialize it */
501 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
502 if (!dev) {
503 dev_err(&interface->dev, "Out of memory\n");
504 goto error;
505 }
506 kref_init(&dev->kref);
507 sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
508 mutex_init(&dev->io_mutex);
509 spin_lock_init(&dev->err_lock);
510 init_usb_anchor(&dev->submitted);
511 init_waitqueue_head(&dev->bulk_in_wait);
512
513 dev->udev = usb_get_dev(interface_to_usbdev(interface));
514 dev->interface = interface;
515
516 /* set up the endpoint information */
517 /* use only the first bulk-in and bulk-out endpoints */
518 iface_desc = interface->cur_altsetting;
519 for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
520 endpoint = &iface_desc->endpoint[i].desc;
521
522 if (!dev->bulk_in_endpointAddr &&
523 usb_endpoint_is_bulk_in(endpoint)) {
524 /* we found a bulk in endpoint */
525 buffer_size = usb_endpoint_maxp(endpoint);
526 dev->bulk_in_size = buffer_size;
527 dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
528 dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
529 if (!dev->bulk_in_buffer) {
530 dev_err(&interface->dev,
531 "Could not allocate bulk_in_buffer\n");
532 goto error;
533 }
534 dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL);
535 if (!dev->bulk_in_urb) {
536 dev_err(&interface->dev,
537 "Could not allocate bulk_in_urb\n");
538 goto error;
539 }
540 }
541
542 if (!dev->bulk_out_endpointAddr &&
543 usb_endpoint_is_bulk_out(endpoint)) {
544 /* we found a bulk out endpoint */
545 dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
546 }
547 }
548 if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
549 dev_err(&interface->dev,
550 "Could not find both bulk-in and bulk-out endpoints\n");
551 goto error;
552 }
553
554 /* save our data pointer in this interface device */
555 usb_set_intfdata(interface, dev);
556
557 /* we can register the device now, as it is ready */
558 retval = usb_register_dev(interface, &skel_class);
559 if (retval) {
560 /* something prevented us from registering this driver */
561 dev_err(&interface->dev,
562 "Not able to get a minor for this device.\n");
563 usb_set_intfdata(interface, NULL);
564 goto error;
565 }
566
567 /* let the user know what node this device is now attached to */
568 dev_info(&interface->dev,
569 "USB Skeleton device now attached to USBSkel-%d",
570 interface->minor);
571 return 0;
572
573error:
574 if (dev)
575 /* this frees allocated memory */
576 kref_put(&dev->kref, skel_delete);
577 return retval;
578}
579
580static void skel_disconnect(struct usb_interface *interface)
581{
582 struct usb_skel *dev;
583 int minor = interface->minor;
584
585 dev = usb_get_intfdata(interface);
586 usb_set_intfdata(interface, NULL);
587
588 /* give back our minor */
589 usb_deregister_dev(interface, &skel_class);
590
591 /* prevent more I/O from starting */
592 mutex_lock(&dev->io_mutex);
593 dev->interface = NULL;
594 mutex_unlock(&dev->io_mutex);
595
596 usb_kill_anchored_urbs(&dev->submitted);
597
598 /* decrement our usage count */
599 kref_put(&dev->kref, skel_delete);
600
601 dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor);
602}
603
604static void skel_draw_down(struct usb_skel *dev)
605{
606 int time;
607
608 time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
609 if (!time)
610 usb_kill_anchored_urbs(&dev->submitted);
611 usb_kill_urb(dev->bulk_in_urb);
612}
613
614static int skel_suspend(struct usb_interface *intf, pm_message_t message)
615{
616 struct usb_skel *dev = usb_get_intfdata(intf);
617
618 if (!dev)
619 return 0;
620 skel_draw_down(dev);
621 return 0;
622}
623
624static int skel_resume(struct usb_interface *intf)
625{
626 return 0;
627}
628
629static int skel_pre_reset(struct usb_interface *intf)
630{
631 struct usb_skel *dev = usb_get_intfdata(intf);
632
633 mutex_lock(&dev->io_mutex);
634 skel_draw_down(dev);
635
636 return 0;
637}
638
639static int skel_post_reset(struct usb_interface *intf)
640{
641 struct usb_skel *dev = usb_get_intfdata(intf);
642
643 /* we are sure no URBs are active - no locking needed */
644 dev->errors = -EPIPE;
645 mutex_unlock(&dev->io_mutex);
646
647 return 0;
648}
649
650static struct usb_driver skel_driver = {
651 .name = "skeleton",
652 .probe = skel_probe,
653 .disconnect = skel_disconnect,
654 .suspend = skel_suspend,
655 .resume = skel_resume,
656 .pre_reset = skel_pre_reset,
657 .post_reset = skel_post_reset,
658 .id_table = skel_table,
659 .supports_autosuspend = 1,
660};
661
662module_usb_driver(skel_driver);
663
664MODULE_LICENSE("GPL");