xref: /linux/drivers/usb/misc/adutux.c (revision 962fad301c33dec69324dc2d9320fd84a119a24c)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * adutux - driver for ADU devices from Ontrak Control Systems
4  * This is an experimental driver. Use at your own risk.
5  * This driver is not supported by Ontrak Control Systems.
6  *
7  * Copyright (c) 2003 John Homppi (SCO, leave this notice here)
8  *
9  * derived from the Lego USB Tower driver 0.56:
10  * Copyright (c) 2003 David Glance <davidgsf@sourceforge.net>
11  *               2001 Juergen Stuber <stuber@loria.fr>
12  * that was derived from USB Skeleton driver - 0.5
13  * Copyright (c) 2001 Greg Kroah-Hartman (greg@kroah.com)
14  *
15  */
16 
17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
18 
19 #include <linux/kernel.h>
20 #include <linux/sched/signal.h>
21 #include <linux/errno.h>
22 #include <linux/slab.h>
23 #include <linux/module.h>
24 #include <linux/usb.h>
25 #include <linux/mutex.h>
26 #include <linux/uaccess.h>
27 
28 #define DRIVER_AUTHOR "John Homppi"
29 #define DRIVER_DESC "adutux (see www.ontrak.net)"
30 
31 /* Define these values to match your device */
32 #define ADU_VENDOR_ID 0x0a07
33 #define ADU_PRODUCT_ID 0x0064
34 
35 /* table of devices that work with this driver */
36 static const struct usb_device_id device_table[] = {
37 	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID) },		/* ADU100 */
38 	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID+20) },	/* ADU120 */
39 	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID+30) },	/* ADU130 */
40 	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID+100) },	/* ADU200 */
41 	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID+108) },	/* ADU208 */
42 	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID+118) },	/* ADU218 */
43 	{ } /* Terminating entry */
44 };
45 
46 MODULE_DEVICE_TABLE(usb, device_table);
47 
48 #ifdef CONFIG_USB_DYNAMIC_MINORS
49 #define ADU_MINOR_BASE	0
50 #else
51 #define ADU_MINOR_BASE	67
52 #endif
53 
54 /* we can have up to this number of device plugged in at once */
55 #define MAX_DEVICES	16
56 
57 #define COMMAND_TIMEOUT	(2*HZ)
58 
59 /*
60  * The locking scheme is a vanilla 3-lock:
61  *   adu_device.buflock: A spinlock, covers what IRQs touch.
62  *   adutux_mutex:       A Static lock to cover open_count. It would also cover
63  *                       any globals, but we don't have them in 2.6.
64  *   adu_device.mtx:     A mutex to hold across sleepers like copy_from_user.
65  *                       It covers all of adu_device, except the open_count
66  *                       and what .buflock covers.
67  */
68 
69 /* Structure to hold all of our device specific stuff */
70 struct adu_device {
71 	struct mutex		mtx;
72 	struct usb_device *udev; /* save off the usb device pointer */
73 	struct usb_interface *interface;
74 	unsigned int		minor; /* the starting minor number for this device */
75 	char			serial_number[8];
76 
77 	int			open_count; /* number of times this port has been opened */
78 	unsigned long		disconnected:1;
79 
80 	char		*read_buffer_primary;
81 	int			read_buffer_length;
82 	char		*read_buffer_secondary;
83 	int			secondary_head;
84 	int			secondary_tail;
85 	spinlock_t		buflock;
86 
87 	wait_queue_head_t	read_wait;
88 	wait_queue_head_t	write_wait;
89 
90 	char		*interrupt_in_buffer;
91 	struct usb_endpoint_descriptor *interrupt_in_endpoint;
92 	struct urb	*interrupt_in_urb;
93 	int			read_urb_finished;
94 
95 	char		*interrupt_out_buffer;
96 	struct usb_endpoint_descriptor *interrupt_out_endpoint;
97 	struct urb	*interrupt_out_urb;
98 	int			out_urb_finished;
99 };
100 
101 static DEFINE_MUTEX(adutux_mutex);
102 
103 static struct usb_driver adu_driver;
104 
105 static inline void adu_debug_data(struct device *dev, const char *function,
106 				  int size, const unsigned char *data)
107 {
108 	dev_dbg(dev, "%s - length = %d, data = %*ph\n",
109 		function, size, size, data);
110 }
111 
112 /*
113  * adu_abort_transfers
114  *      aborts transfers and frees associated data structures
115  */
116 static void adu_abort_transfers(struct adu_device *dev)
117 {
118 	unsigned long flags;
119 
120 	if (dev->disconnected)
121 		return;
122 
123 	/* shutdown transfer */
124 
125 	/* XXX Anchor these instead */
126 	spin_lock_irqsave(&dev->buflock, flags);
127 	if (!dev->read_urb_finished) {
128 		spin_unlock_irqrestore(&dev->buflock, flags);
129 		usb_kill_urb(dev->interrupt_in_urb);
130 	} else
131 		spin_unlock_irqrestore(&dev->buflock, flags);
132 
133 	spin_lock_irqsave(&dev->buflock, flags);
134 	if (!dev->out_urb_finished) {
135 		spin_unlock_irqrestore(&dev->buflock, flags);
136 		wait_event_timeout(dev->write_wait, dev->out_urb_finished,
137 			COMMAND_TIMEOUT);
138 		usb_kill_urb(dev->interrupt_out_urb);
139 	} else
140 		spin_unlock_irqrestore(&dev->buflock, flags);
141 }
142 
143 static void adu_delete(struct adu_device *dev)
144 {
145 	/* free data structures */
146 	usb_free_urb(dev->interrupt_in_urb);
147 	usb_free_urb(dev->interrupt_out_urb);
148 	kfree(dev->read_buffer_primary);
149 	kfree(dev->read_buffer_secondary);
150 	kfree(dev->interrupt_in_buffer);
151 	kfree(dev->interrupt_out_buffer);
152 	usb_put_dev(dev->udev);
153 	kfree(dev);
154 }
155 
156 static void adu_interrupt_in_callback(struct urb *urb)
157 {
158 	struct adu_device *dev = urb->context;
159 	int status = urb->status;
160 	unsigned long flags;
161 
162 	adu_debug_data(&dev->udev->dev, __func__,
163 		       urb->actual_length, urb->transfer_buffer);
164 
165 	spin_lock_irqsave(&dev->buflock, flags);
166 
167 	if (status != 0) {
168 		if ((status != -ENOENT) && (status != -ECONNRESET) &&
169 			(status != -ESHUTDOWN)) {
170 			dev_dbg(&dev->udev->dev,
171 				"%s : nonzero status received: %d\n",
172 				__func__, status);
173 		}
174 		goto exit;
175 	}
176 
177 	if (urb->actual_length > 0 && dev->interrupt_in_buffer[0] != 0x00) {
178 		if (dev->read_buffer_length <
179 		    (4 * usb_endpoint_maxp(dev->interrupt_in_endpoint)) -
180 		     (urb->actual_length)) {
181 			memcpy (dev->read_buffer_primary +
182 				dev->read_buffer_length,
183 				dev->interrupt_in_buffer, urb->actual_length);
184 
185 			dev->read_buffer_length += urb->actual_length;
186 			dev_dbg(&dev->udev->dev,"%s reading  %d\n", __func__,
187 				urb->actual_length);
188 		} else {
189 			dev_dbg(&dev->udev->dev,"%s : read_buffer overflow\n",
190 				__func__);
191 		}
192 	}
193 
194 exit:
195 	dev->read_urb_finished = 1;
196 	spin_unlock_irqrestore(&dev->buflock, flags);
197 	/* always wake up so we recover from errors */
198 	wake_up_interruptible(&dev->read_wait);
199 }
200 
201 static void adu_interrupt_out_callback(struct urb *urb)
202 {
203 	struct adu_device *dev = urb->context;
204 	int status = urb->status;
205 	unsigned long flags;
206 
207 	adu_debug_data(&dev->udev->dev, __func__,
208 		       urb->actual_length, urb->transfer_buffer);
209 
210 	if (status != 0) {
211 		if ((status != -ENOENT) &&
212 		    (status != -ECONNRESET)) {
213 			dev_dbg(&dev->udev->dev,
214 				"%s :nonzero status received: %d\n", __func__,
215 				status);
216 		}
217 		return;
218 	}
219 
220 	spin_lock_irqsave(&dev->buflock, flags);
221 	dev->out_urb_finished = 1;
222 	wake_up(&dev->write_wait);
223 	spin_unlock_irqrestore(&dev->buflock, flags);
224 }
225 
226 static int adu_open(struct inode *inode, struct file *file)
227 {
228 	struct adu_device *dev = NULL;
229 	struct usb_interface *interface;
230 	int subminor;
231 	int retval;
232 
233 	subminor = iminor(inode);
234 
235 	retval = mutex_lock_interruptible(&adutux_mutex);
236 	if (retval)
237 		goto exit_no_lock;
238 
239 	interface = usb_find_interface(&adu_driver, subminor);
240 	if (!interface) {
241 		pr_err("%s - error, can't find device for minor %d\n",
242 		       __func__, subminor);
243 		retval = -ENODEV;
244 		goto exit_no_device;
245 	}
246 
247 	dev = usb_get_intfdata(interface);
248 	if (!dev) {
249 		retval = -ENODEV;
250 		goto exit_no_device;
251 	}
252 
253 	/* check that nobody else is using the device */
254 	if (dev->open_count) {
255 		retval = -EBUSY;
256 		goto exit_no_device;
257 	}
258 
259 	++dev->open_count;
260 	dev_dbg(&dev->udev->dev, "%s: open count %d\n", __func__,
261 		dev->open_count);
262 
263 	/* save device in the file's private structure */
264 	file->private_data = dev;
265 
266 	/* initialize in direction */
267 	dev->read_buffer_length = 0;
268 
269 	/* fixup first read by having urb waiting for it */
270 	usb_fill_int_urb(dev->interrupt_in_urb, dev->udev,
271 			 usb_rcvintpipe(dev->udev,
272 					dev->interrupt_in_endpoint->bEndpointAddress),
273 			 dev->interrupt_in_buffer,
274 			 usb_endpoint_maxp(dev->interrupt_in_endpoint),
275 			 adu_interrupt_in_callback, dev,
276 			 dev->interrupt_in_endpoint->bInterval);
277 	dev->read_urb_finished = 0;
278 	if (usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL))
279 		dev->read_urb_finished = 1;
280 	/* we ignore failure */
281 	/* end of fixup for first read */
282 
283 	/* initialize out direction */
284 	dev->out_urb_finished = 1;
285 
286 	retval = 0;
287 
288 exit_no_device:
289 	mutex_unlock(&adutux_mutex);
290 exit_no_lock:
291 	return retval;
292 }
293 
294 static void adu_release_internal(struct adu_device *dev)
295 {
296 	/* decrement our usage count for the device */
297 	--dev->open_count;
298 	dev_dbg(&dev->udev->dev, "%s : open count %d\n", __func__,
299 		dev->open_count);
300 	if (dev->open_count <= 0) {
301 		adu_abort_transfers(dev);
302 		dev->open_count = 0;
303 	}
304 }
305 
306 static int adu_release(struct inode *inode, struct file *file)
307 {
308 	struct adu_device *dev;
309 	int retval = 0;
310 
311 	if (file == NULL) {
312 		retval = -ENODEV;
313 		goto exit;
314 	}
315 
316 	dev = file->private_data;
317 	if (dev == NULL) {
318 		retval = -ENODEV;
319 		goto exit;
320 	}
321 
322 	mutex_lock(&adutux_mutex); /* not interruptible */
323 
324 	if (dev->open_count <= 0) {
325 		dev_dbg(&dev->udev->dev, "%s : device not opened\n", __func__);
326 		retval = -ENODEV;
327 		goto unlock;
328 	}
329 
330 	adu_release_internal(dev);
331 	if (dev->disconnected) {
332 		/* the device was unplugged before the file was released */
333 		if (!dev->open_count)	/* ... and we're the last user */
334 			adu_delete(dev);
335 	}
336 unlock:
337 	mutex_unlock(&adutux_mutex);
338 exit:
339 	return retval;
340 }
341 
342 static ssize_t adu_read(struct file *file, __user char *buffer, size_t count,
343 			loff_t *ppos)
344 {
345 	struct adu_device *dev;
346 	size_t bytes_read = 0;
347 	size_t bytes_to_read = count;
348 	int retval = 0;
349 	int timeout = 0;
350 	int should_submit = 0;
351 	unsigned long flags;
352 	DECLARE_WAITQUEUE(wait, current);
353 
354 	dev = file->private_data;
355 	if (mutex_lock_interruptible(&dev->mtx))
356 		return -ERESTARTSYS;
357 
358 	/* verify that the device wasn't unplugged */
359 	if (dev->disconnected) {
360 		retval = -ENODEV;
361 		pr_err("No device or device unplugged %d\n", retval);
362 		goto exit;
363 	}
364 
365 	/* verify that some data was requested */
366 	if (count == 0) {
367 		dev_dbg(&dev->udev->dev, "%s : read request of 0 bytes\n",
368 			__func__);
369 		goto exit;
370 	}
371 
372 	timeout = COMMAND_TIMEOUT;
373 	dev_dbg(&dev->udev->dev, "%s : about to start looping\n", __func__);
374 	while (bytes_to_read) {
375 		size_t data_in_secondary = dev->secondary_tail - dev->secondary_head;
376 		dev_dbg(&dev->udev->dev,
377 			"%s : while, data_in_secondary=%zu, status=%d\n",
378 			__func__, data_in_secondary,
379 			dev->interrupt_in_urb->status);
380 
381 		if (data_in_secondary) {
382 			/* drain secondary buffer */
383 			size_t amount = min(bytes_to_read, data_in_secondary);
384 			if (copy_to_user(buffer, dev->read_buffer_secondary+dev->secondary_head, amount)) {
385 				retval = -EFAULT;
386 				goto exit;
387 			}
388 			dev->secondary_head += amount;
389 			bytes_read += amount;
390 			bytes_to_read -= amount;
391 		} else {
392 			/* we check the primary buffer */
393 			spin_lock_irqsave (&dev->buflock, flags);
394 			if (dev->read_buffer_length) {
395 				/* we secure access to the primary */
396 				char *tmp;
397 				dev_dbg(&dev->udev->dev,
398 					"%s : swap, read_buffer_length = %d\n",
399 					__func__, dev->read_buffer_length);
400 				tmp = dev->read_buffer_secondary;
401 				dev->read_buffer_secondary = dev->read_buffer_primary;
402 				dev->read_buffer_primary = tmp;
403 				dev->secondary_head = 0;
404 				dev->secondary_tail = dev->read_buffer_length;
405 				dev->read_buffer_length = 0;
406 				spin_unlock_irqrestore(&dev->buflock, flags);
407 				/* we have a free buffer so use it */
408 				should_submit = 1;
409 			} else {
410 				/* even the primary was empty - we may need to do IO */
411 				if (!dev->read_urb_finished) {
412 					/* somebody is doing IO */
413 					spin_unlock_irqrestore(&dev->buflock, flags);
414 					dev_dbg(&dev->udev->dev,
415 						"%s : submitted already\n",
416 						__func__);
417 				} else {
418 					/* we must initiate input */
419 					dev_dbg(&dev->udev->dev,
420 						"%s : initiate input\n",
421 						__func__);
422 					dev->read_urb_finished = 0;
423 					spin_unlock_irqrestore(&dev->buflock, flags);
424 
425 					usb_fill_int_urb(dev->interrupt_in_urb, dev->udev,
426 							usb_rcvintpipe(dev->udev,
427 								dev->interrupt_in_endpoint->bEndpointAddress),
428 							 dev->interrupt_in_buffer,
429 							 usb_endpoint_maxp(dev->interrupt_in_endpoint),
430 							 adu_interrupt_in_callback,
431 							 dev,
432 							 dev->interrupt_in_endpoint->bInterval);
433 					retval = usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
434 					if (retval) {
435 						dev->read_urb_finished = 1;
436 						if (retval == -ENOMEM) {
437 							retval = bytes_read ? bytes_read : -ENOMEM;
438 						}
439 						dev_dbg(&dev->udev->dev,
440 							"%s : submit failed\n",
441 							__func__);
442 						goto exit;
443 					}
444 				}
445 
446 				/* we wait for I/O to complete */
447 				set_current_state(TASK_INTERRUPTIBLE);
448 				add_wait_queue(&dev->read_wait, &wait);
449 				spin_lock_irqsave(&dev->buflock, flags);
450 				if (!dev->read_urb_finished) {
451 					spin_unlock_irqrestore(&dev->buflock, flags);
452 					timeout = schedule_timeout(COMMAND_TIMEOUT);
453 				} else {
454 					spin_unlock_irqrestore(&dev->buflock, flags);
455 					set_current_state(TASK_RUNNING);
456 				}
457 				remove_wait_queue(&dev->read_wait, &wait);
458 
459 				if (timeout <= 0) {
460 					dev_dbg(&dev->udev->dev,
461 						"%s : timeout\n", __func__);
462 					retval = bytes_read ? bytes_read : -ETIMEDOUT;
463 					goto exit;
464 				}
465 
466 				if (signal_pending(current)) {
467 					dev_dbg(&dev->udev->dev,
468 						"%s : signal pending\n",
469 						__func__);
470 					retval = bytes_read ? bytes_read : -EINTR;
471 					goto exit;
472 				}
473 			}
474 		}
475 	}
476 
477 	retval = bytes_read;
478 	/* if the primary buffer is empty then use it */
479 	spin_lock_irqsave(&dev->buflock, flags);
480 	if (should_submit && dev->read_urb_finished) {
481 		dev->read_urb_finished = 0;
482 		spin_unlock_irqrestore(&dev->buflock, flags);
483 		usb_fill_int_urb(dev->interrupt_in_urb, dev->udev,
484 				 usb_rcvintpipe(dev->udev,
485 					dev->interrupt_in_endpoint->bEndpointAddress),
486 				dev->interrupt_in_buffer,
487 				usb_endpoint_maxp(dev->interrupt_in_endpoint),
488 				adu_interrupt_in_callback,
489 				dev,
490 				dev->interrupt_in_endpoint->bInterval);
491 		if (usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL) != 0)
492 			dev->read_urb_finished = 1;
493 		/* we ignore failure */
494 	} else {
495 		spin_unlock_irqrestore(&dev->buflock, flags);
496 	}
497 
498 exit:
499 	/* unlock the device */
500 	mutex_unlock(&dev->mtx);
501 
502 	return retval;
503 }
504 
505 static ssize_t adu_write(struct file *file, const __user char *buffer,
506 			 size_t count, loff_t *ppos)
507 {
508 	DECLARE_WAITQUEUE(waita, current);
509 	struct adu_device *dev;
510 	size_t bytes_written = 0;
511 	size_t bytes_to_write;
512 	size_t buffer_size;
513 	unsigned long flags;
514 	int retval;
515 
516 	dev = file->private_data;
517 
518 	retval = mutex_lock_interruptible(&dev->mtx);
519 	if (retval)
520 		goto exit_nolock;
521 
522 	/* verify that the device wasn't unplugged */
523 	if (dev->disconnected) {
524 		retval = -ENODEV;
525 		pr_err("No device or device unplugged %d\n", retval);
526 		goto exit;
527 	}
528 
529 	/* verify that we actually have some data to write */
530 	if (count == 0) {
531 		dev_dbg(&dev->udev->dev, "%s : write request of 0 bytes\n",
532 			__func__);
533 		goto exit;
534 	}
535 
536 	while (count > 0) {
537 		add_wait_queue(&dev->write_wait, &waita);
538 		set_current_state(TASK_INTERRUPTIBLE);
539 		spin_lock_irqsave(&dev->buflock, flags);
540 		if (!dev->out_urb_finished) {
541 			spin_unlock_irqrestore(&dev->buflock, flags);
542 
543 			mutex_unlock(&dev->mtx);
544 			if (signal_pending(current)) {
545 				dev_dbg(&dev->udev->dev, "%s : interrupted\n",
546 					__func__);
547 				set_current_state(TASK_RUNNING);
548 				retval = -EINTR;
549 				goto exit_onqueue;
550 			}
551 			if (schedule_timeout(COMMAND_TIMEOUT) == 0) {
552 				dev_dbg(&dev->udev->dev,
553 					"%s - command timed out.\n", __func__);
554 				retval = -ETIMEDOUT;
555 				goto exit_onqueue;
556 			}
557 			remove_wait_queue(&dev->write_wait, &waita);
558 			retval = mutex_lock_interruptible(&dev->mtx);
559 			if (retval) {
560 				retval = bytes_written ? bytes_written : retval;
561 				goto exit_nolock;
562 			}
563 
564 			dev_dbg(&dev->udev->dev,
565 				"%s : in progress, count = %zd\n",
566 				__func__, count);
567 		} else {
568 			spin_unlock_irqrestore(&dev->buflock, flags);
569 			set_current_state(TASK_RUNNING);
570 			remove_wait_queue(&dev->write_wait, &waita);
571 			dev_dbg(&dev->udev->dev, "%s : sending, count = %zd\n",
572 				__func__, count);
573 
574 			/* write the data into interrupt_out_buffer from userspace */
575 			buffer_size = usb_endpoint_maxp(dev->interrupt_out_endpoint);
576 			bytes_to_write = count > buffer_size ? buffer_size : count;
577 			dev_dbg(&dev->udev->dev,
578 				"%s : buffer_size = %zd, count = %zd, bytes_to_write = %zd\n",
579 				__func__, buffer_size, count, bytes_to_write);
580 
581 			if (copy_from_user(dev->interrupt_out_buffer, buffer, bytes_to_write) != 0) {
582 				retval = -EFAULT;
583 				goto exit;
584 			}
585 
586 			/* send off the urb */
587 			usb_fill_int_urb(
588 				dev->interrupt_out_urb,
589 				dev->udev,
590 				usb_sndintpipe(dev->udev, dev->interrupt_out_endpoint->bEndpointAddress),
591 				dev->interrupt_out_buffer,
592 				bytes_to_write,
593 				adu_interrupt_out_callback,
594 				dev,
595 				dev->interrupt_out_endpoint->bInterval);
596 			dev->interrupt_out_urb->actual_length = bytes_to_write;
597 			dev->out_urb_finished = 0;
598 			retval = usb_submit_urb(dev->interrupt_out_urb, GFP_KERNEL);
599 			if (retval < 0) {
600 				dev->out_urb_finished = 1;
601 				dev_err(&dev->udev->dev, "Couldn't submit "
602 					"interrupt_out_urb %d\n", retval);
603 				goto exit;
604 			}
605 
606 			buffer += bytes_to_write;
607 			count -= bytes_to_write;
608 
609 			bytes_written += bytes_to_write;
610 		}
611 	}
612 	mutex_unlock(&dev->mtx);
613 	return bytes_written;
614 
615 exit:
616 	mutex_unlock(&dev->mtx);
617 exit_nolock:
618 	return retval;
619 
620 exit_onqueue:
621 	remove_wait_queue(&dev->write_wait, &waita);
622 	return retval;
623 }
624 
625 /* file operations needed when we register this driver */
626 static const struct file_operations adu_fops = {
627 	.owner = THIS_MODULE,
628 	.read  = adu_read,
629 	.write = adu_write,
630 	.open = adu_open,
631 	.release = adu_release,
632 	.llseek = noop_llseek,
633 };
634 
635 /*
636  * usb class driver info in order to get a minor number from the usb core,
637  * and to have the device registered with devfs and the driver core
638  */
639 static struct usb_class_driver adu_class = {
640 	.name = "usb/adutux%d",
641 	.fops = &adu_fops,
642 	.minor_base = ADU_MINOR_BASE,
643 };
644 
645 /*
646  * adu_probe
647  *
648  * Called by the usb core when a new device is connected that it thinks
649  * this driver might be interested in.
650  */
651 static int adu_probe(struct usb_interface *interface,
652 		     const struct usb_device_id *id)
653 {
654 	struct usb_device *udev = interface_to_usbdev(interface);
655 	struct adu_device *dev = NULL;
656 	int retval = -ENOMEM;
657 	int in_end_size;
658 	int out_end_size;
659 	int res;
660 
661 	/* allocate memory for our device state and initialize it */
662 	dev = kzalloc(sizeof(struct adu_device), GFP_KERNEL);
663 	if (!dev)
664 		return -ENOMEM;
665 
666 	mutex_init(&dev->mtx);
667 	spin_lock_init(&dev->buflock);
668 	dev->udev = usb_get_dev(udev);
669 	init_waitqueue_head(&dev->read_wait);
670 	init_waitqueue_head(&dev->write_wait);
671 
672 	res = usb_find_common_endpoints_reverse(interface->cur_altsetting,
673 			NULL, NULL,
674 			&dev->interrupt_in_endpoint,
675 			&dev->interrupt_out_endpoint);
676 	if (res) {
677 		dev_err(&interface->dev, "interrupt endpoints not found\n");
678 		retval = res;
679 		goto error;
680 	}
681 
682 	in_end_size = usb_endpoint_maxp(dev->interrupt_in_endpoint);
683 	out_end_size = usb_endpoint_maxp(dev->interrupt_out_endpoint);
684 
685 	dev->read_buffer_primary = kmalloc((4 * in_end_size), GFP_KERNEL);
686 	if (!dev->read_buffer_primary)
687 		goto error;
688 
689 	/* debug code prime the buffer */
690 	memset(dev->read_buffer_primary, 'a', in_end_size);
691 	memset(dev->read_buffer_primary + in_end_size, 'b', in_end_size);
692 	memset(dev->read_buffer_primary + (2 * in_end_size), 'c', in_end_size);
693 	memset(dev->read_buffer_primary + (3 * in_end_size), 'd', in_end_size);
694 
695 	dev->read_buffer_secondary = kmalloc((4 * in_end_size), GFP_KERNEL);
696 	if (!dev->read_buffer_secondary)
697 		goto error;
698 
699 	/* debug code prime the buffer */
700 	memset(dev->read_buffer_secondary, 'e', in_end_size);
701 	memset(dev->read_buffer_secondary + in_end_size, 'f', in_end_size);
702 	memset(dev->read_buffer_secondary + (2 * in_end_size), 'g', in_end_size);
703 	memset(dev->read_buffer_secondary + (3 * in_end_size), 'h', in_end_size);
704 
705 	dev->interrupt_in_buffer = kmalloc(in_end_size, GFP_KERNEL);
706 	if (!dev->interrupt_in_buffer)
707 		goto error;
708 
709 	/* debug code prime the buffer */
710 	memset(dev->interrupt_in_buffer, 'i', in_end_size);
711 
712 	dev->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
713 	if (!dev->interrupt_in_urb)
714 		goto error;
715 	dev->interrupt_out_buffer = kmalloc(out_end_size, GFP_KERNEL);
716 	if (!dev->interrupt_out_buffer)
717 		goto error;
718 	dev->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
719 	if (!dev->interrupt_out_urb)
720 		goto error;
721 
722 	if (!usb_string(udev, udev->descriptor.iSerialNumber, dev->serial_number,
723 			sizeof(dev->serial_number))) {
724 		dev_err(&interface->dev, "Could not retrieve serial number\n");
725 		retval = -EIO;
726 		goto error;
727 	}
728 	dev_dbg(&interface->dev,"serial_number=%s", dev->serial_number);
729 
730 	/* we can register the device now, as it is ready */
731 	usb_set_intfdata(interface, dev);
732 
733 	retval = usb_register_dev(interface, &adu_class);
734 
735 	if (retval) {
736 		/* something prevented us from registering this driver */
737 		dev_err(&interface->dev, "Not able to get a minor for this device.\n");
738 		usb_set_intfdata(interface, NULL);
739 		goto error;
740 	}
741 
742 	dev->minor = interface->minor;
743 
744 	/* let the user know what node this device is now attached to */
745 	dev_info(&interface->dev, "ADU%d %s now attached to /dev/usb/adutux%d\n",
746 		 le16_to_cpu(udev->descriptor.idProduct), dev->serial_number,
747 		 (dev->minor - ADU_MINOR_BASE));
748 
749 	return 0;
750 
751 error:
752 	adu_delete(dev);
753 	return retval;
754 }
755 
756 /*
757  * adu_disconnect
758  *
759  * Called by the usb core when the device is removed from the system.
760  */
761 static void adu_disconnect(struct usb_interface *interface)
762 {
763 	struct adu_device *dev;
764 
765 	dev = usb_get_intfdata(interface);
766 
767 	usb_deregister_dev(interface, &adu_class);
768 
769 	usb_poison_urb(dev->interrupt_in_urb);
770 	usb_poison_urb(dev->interrupt_out_urb);
771 
772 	mutex_lock(&adutux_mutex);
773 	usb_set_intfdata(interface, NULL);
774 
775 	mutex_lock(&dev->mtx);	/* not interruptible */
776 	dev->disconnected = 1;
777 	mutex_unlock(&dev->mtx);
778 
779 	/* if the device is not opened, then we clean up right now */
780 	if (!dev->open_count)
781 		adu_delete(dev);
782 
783 	mutex_unlock(&adutux_mutex);
784 }
785 
786 /* usb specific object needed to register this driver with the usb subsystem */
787 static struct usb_driver adu_driver = {
788 	.name = "adutux",
789 	.probe = adu_probe,
790 	.disconnect = adu_disconnect,
791 	.id_table = device_table,
792 };
793 
794 module_usb_driver(adu_driver);
795 
796 MODULE_AUTHOR(DRIVER_AUTHOR);
797 MODULE_DESCRIPTION(DRIVER_DESC);
798 MODULE_LICENSE("GPL");
799