xref: /openbmc/linux/drivers/usb/misc/adutux.c (revision 4e1a33b1)
1 /*
2  * adutux - driver for ADU devices from Ontrak Control Systems
3  * This is an experimental driver. Use at your own risk.
4  * This driver is not supported by Ontrak Control Systems.
5  *
6  * Copyright (c) 2003 John Homppi (SCO, leave this notice here)
7  *
8  * This program is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU General Public License as
10  * published by the Free Software Foundation; either version 2 of
11  * the License, or (at your option) any later version.
12  *
13  * derived from the Lego USB Tower driver 0.56:
14  * Copyright (c) 2003 David Glance <davidgsf@sourceforge.net>
15  *               2001 Juergen Stuber <stuber@loria.fr>
16  * that was derived from USB Skeleton driver - 0.5
17  * Copyright (c) 2001 Greg Kroah-Hartman (greg@kroah.com)
18  *
19  */
20 
21 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
22 
23 #include <linux/kernel.h>
24 #include <linux/errno.h>
25 #include <linux/slab.h>
26 #include <linux/module.h>
27 #include <linux/usb.h>
28 #include <linux/mutex.h>
29 #include <linux/uaccess.h>
30 
31 /* Version Information */
32 #define DRIVER_VERSION "v0.0.13"
33 #define DRIVER_AUTHOR "John Homppi"
34 #define DRIVER_DESC "adutux (see www.ontrak.net)"
35 
36 /* Define these values to match your device */
37 #define ADU_VENDOR_ID 0x0a07
38 #define ADU_PRODUCT_ID 0x0064
39 
40 /* table of devices that work with this driver */
41 static const struct usb_device_id device_table[] = {
42 	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID) },		/* ADU100 */
43 	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID+20) },	/* ADU120 */
44 	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID+30) },	/* ADU130 */
45 	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID+100) },	/* ADU200 */
46 	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID+108) },	/* ADU208 */
47 	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID+118) },	/* ADU218 */
48 	{ } /* Terminating entry */
49 };
50 
51 MODULE_DEVICE_TABLE(usb, device_table);
52 
53 #ifdef CONFIG_USB_DYNAMIC_MINORS
54 #define ADU_MINOR_BASE	0
55 #else
56 #define ADU_MINOR_BASE	67
57 #endif
58 
59 /* we can have up to this number of device plugged in at once */
60 #define MAX_DEVICES	16
61 
62 #define COMMAND_TIMEOUT	(2*HZ)	/* 60 second timeout for a command */
63 
64 /*
65  * The locking scheme is a vanilla 3-lock:
66  *   adu_device.buflock: A spinlock, covers what IRQs touch.
67  *   adutux_mutex:       A Static lock to cover open_count. It would also cover
68  *                       any globals, but we don't have them in 2.6.
69  *   adu_device.mtx:     A mutex to hold across sleepers like copy_from_user.
70  *                       It covers all of adu_device, except the open_count
71  *                       and what .buflock covers.
72  */
73 
74 /* Structure to hold all of our device specific stuff */
75 struct adu_device {
76 	struct mutex		mtx;
77 	struct usb_device *udev; /* save off the usb device pointer */
78 	struct usb_interface *interface;
79 	unsigned int		minor; /* the starting minor number for this device */
80 	char			serial_number[8];
81 
82 	int			open_count; /* number of times this port has been opened */
83 
84 	char		*read_buffer_primary;
85 	int			read_buffer_length;
86 	char		*read_buffer_secondary;
87 	int			secondary_head;
88 	int			secondary_tail;
89 	spinlock_t		buflock;
90 
91 	wait_queue_head_t	read_wait;
92 	wait_queue_head_t	write_wait;
93 
94 	char		*interrupt_in_buffer;
95 	struct usb_endpoint_descriptor *interrupt_in_endpoint;
96 	struct urb	*interrupt_in_urb;
97 	int			read_urb_finished;
98 
99 	char		*interrupt_out_buffer;
100 	struct usb_endpoint_descriptor *interrupt_out_endpoint;
101 	struct urb	*interrupt_out_urb;
102 	int			out_urb_finished;
103 };
104 
105 static DEFINE_MUTEX(adutux_mutex);
106 
107 static struct usb_driver adu_driver;
108 
109 static inline void adu_debug_data(struct device *dev, const char *function,
110 				  int size, const unsigned char *data)
111 {
112 	dev_dbg(dev, "%s - length = %d, data = %*ph\n",
113 		function, size, size, data);
114 }
115 
116 /**
117  * adu_abort_transfers
118  *      aborts transfers and frees associated data structures
119  */
120 static void adu_abort_transfers(struct adu_device *dev)
121 {
122 	unsigned long flags;
123 
124 	if (dev->udev == NULL)
125 		return;
126 
127 	/* shutdown transfer */
128 
129 	/* XXX Anchor these instead */
130 	spin_lock_irqsave(&dev->buflock, flags);
131 	if (!dev->read_urb_finished) {
132 		spin_unlock_irqrestore(&dev->buflock, flags);
133 		usb_kill_urb(dev->interrupt_in_urb);
134 	} else
135 		spin_unlock_irqrestore(&dev->buflock, flags);
136 
137 	spin_lock_irqsave(&dev->buflock, flags);
138 	if (!dev->out_urb_finished) {
139 		spin_unlock_irqrestore(&dev->buflock, flags);
140 		usb_kill_urb(dev->interrupt_out_urb);
141 	} else
142 		spin_unlock_irqrestore(&dev->buflock, flags);
143 }
144 
145 static void adu_delete(struct adu_device *dev)
146 {
147 	/* free data structures */
148 	usb_free_urb(dev->interrupt_in_urb);
149 	usb_free_urb(dev->interrupt_out_urb);
150 	kfree(dev->read_buffer_primary);
151 	kfree(dev->read_buffer_secondary);
152 	kfree(dev->interrupt_in_buffer);
153 	kfree(dev->interrupt_out_buffer);
154 	kfree(dev);
155 }
156 
157 static void adu_interrupt_in_callback(struct urb *urb)
158 {
159 	struct adu_device *dev = urb->context;
160 	int status = urb->status;
161 
162 	adu_debug_data(&dev->udev->dev, __func__,
163 		       urb->actual_length, urb->transfer_buffer);
164 
165 	spin_lock(&dev->buflock);
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(&dev->buflock);
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 
206 	adu_debug_data(&dev->udev->dev, __func__,
207 		       urb->actual_length, urb->transfer_buffer);
208 
209 	if (status != 0) {
210 		if ((status != -ENOENT) &&
211 		    (status != -ECONNRESET)) {
212 			dev_dbg(&dev->udev->dev,
213 				"%s :nonzero status received: %d\n", __func__,
214 				status);
215 		}
216 		return;
217 	}
218 
219 	spin_lock(&dev->buflock);
220 	dev->out_urb_finished = 1;
221 	wake_up(&dev->write_wait);
222 	spin_unlock(&dev->buflock);
223 }
224 
225 static int adu_open(struct inode *inode, struct file *file)
226 {
227 	struct adu_device *dev = NULL;
228 	struct usb_interface *interface;
229 	int subminor;
230 	int retval;
231 
232 	subminor = iminor(inode);
233 
234 	retval = mutex_lock_interruptible(&adutux_mutex);
235 	if (retval)
236 		goto exit_no_lock;
237 
238 	interface = usb_find_interface(&adu_driver, subminor);
239 	if (!interface) {
240 		pr_err("%s - error, can't find device for minor %d\n",
241 		       __func__, subminor);
242 		retval = -ENODEV;
243 		goto exit_no_device;
244 	}
245 
246 	dev = usb_get_intfdata(interface);
247 	if (!dev || !dev->udev) {
248 		retval = -ENODEV;
249 		goto exit_no_device;
250 	}
251 
252 	/* check that nobody else is using the device */
253 	if (dev->open_count) {
254 		retval = -EBUSY;
255 		goto exit_no_device;
256 	}
257 
258 	++dev->open_count;
259 	dev_dbg(&dev->udev->dev, "%s: open count %d\n", __func__,
260 		dev->open_count);
261 
262 	/* save device in the file's private structure */
263 	file->private_data = dev;
264 
265 	/* initialize in direction */
266 	dev->read_buffer_length = 0;
267 
268 	/* fixup first read by having urb waiting for it */
269 	usb_fill_int_urb(dev->interrupt_in_urb, dev->udev,
270 			 usb_rcvintpipe(dev->udev,
271 					dev->interrupt_in_endpoint->bEndpointAddress),
272 			 dev->interrupt_in_buffer,
273 			 usb_endpoint_maxp(dev->interrupt_in_endpoint),
274 			 adu_interrupt_in_callback, dev,
275 			 dev->interrupt_in_endpoint->bInterval);
276 	dev->read_urb_finished = 0;
277 	if (usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL))
278 		dev->read_urb_finished = 1;
279 	/* we ignore failure */
280 	/* end of fixup for first read */
281 
282 	/* initialize out direction */
283 	dev->out_urb_finished = 1;
284 
285 	retval = 0;
286 
287 exit_no_device:
288 	mutex_unlock(&adutux_mutex);
289 exit_no_lock:
290 	return retval;
291 }
292 
293 static void adu_release_internal(struct adu_device *dev)
294 {
295 	/* decrement our usage count for the device */
296 	--dev->open_count;
297 	dev_dbg(&dev->udev->dev, "%s : open count %d\n", __func__,
298 		dev->open_count);
299 	if (dev->open_count <= 0) {
300 		adu_abort_transfers(dev);
301 		dev->open_count = 0;
302 	}
303 }
304 
305 static int adu_release(struct inode *inode, struct file *file)
306 {
307 	struct adu_device *dev;
308 	int retval = 0;
309 
310 	if (file == NULL) {
311 		retval = -ENODEV;
312 		goto exit;
313 	}
314 
315 	dev = file->private_data;
316 	if (dev == NULL) {
317 		retval = -ENODEV;
318 		goto exit;
319 	}
320 
321 	mutex_lock(&adutux_mutex); /* not interruptible */
322 
323 	if (dev->open_count <= 0) {
324 		dev_dbg(&dev->udev->dev, "%s : device not opened\n", __func__);
325 		retval = -ENODEV;
326 		goto unlock;
327 	}
328 
329 	adu_release_internal(dev);
330 	if (dev->udev == NULL) {
331 		/* the device was unplugged before the file was released */
332 		if (!dev->open_count)	/* ... and we're the last user */
333 			adu_delete(dev);
334 	}
335 unlock:
336 	mutex_unlock(&adutux_mutex);
337 exit:
338 	return retval;
339 }
340 
341 static ssize_t adu_read(struct file *file, __user char *buffer, size_t count,
342 			loff_t *ppos)
343 {
344 	struct adu_device *dev;
345 	size_t bytes_read = 0;
346 	size_t bytes_to_read = count;
347 	int i;
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->udev == NULL) {
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 		int data_in_secondary = dev->secondary_tail - dev->secondary_head;
376 		dev_dbg(&dev->udev->dev,
377 			"%s : while, data_in_secondary=%d, 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 			int amount = bytes_to_read < data_in_secondary ? bytes_to_read : data_in_secondary;
384 			i = copy_to_user(buffer, dev->read_buffer_secondary+dev->secondary_head, amount);
385 			if (i) {
386 				retval = -EFAULT;
387 				goto exit;
388 			}
389 			dev->secondary_head += (amount - i);
390 			bytes_read += (amount - i);
391 			bytes_to_read -= (amount - i);
392 		} else {
393 			/* we check the primary buffer */
394 			spin_lock_irqsave (&dev->buflock, flags);
395 			if (dev->read_buffer_length) {
396 				/* we secure access to the primary */
397 				char *tmp;
398 				dev_dbg(&dev->udev->dev,
399 					"%s : swap, read_buffer_length = %d\n",
400 					__func__, dev->read_buffer_length);
401 				tmp = dev->read_buffer_secondary;
402 				dev->read_buffer_secondary = dev->read_buffer_primary;
403 				dev->read_buffer_primary = tmp;
404 				dev->secondary_head = 0;
405 				dev->secondary_tail = dev->read_buffer_length;
406 				dev->read_buffer_length = 0;
407 				spin_unlock_irqrestore(&dev->buflock, flags);
408 				/* we have a free buffer so use it */
409 				should_submit = 1;
410 			} else {
411 				/* even the primary was empty - we may need to do IO */
412 				if (!dev->read_urb_finished) {
413 					/* somebody is doing IO */
414 					spin_unlock_irqrestore(&dev->buflock, flags);
415 					dev_dbg(&dev->udev->dev,
416 						"%s : submitted already\n",
417 						__func__);
418 				} else {
419 					/* we must initiate input */
420 					dev_dbg(&dev->udev->dev,
421 						"%s : initiate input\n",
422 						__func__);
423 					dev->read_urb_finished = 0;
424 					spin_unlock_irqrestore(&dev->buflock, flags);
425 
426 					usb_fill_int_urb(dev->interrupt_in_urb, dev->udev,
427 							usb_rcvintpipe(dev->udev,
428 								dev->interrupt_in_endpoint->bEndpointAddress),
429 							 dev->interrupt_in_buffer,
430 							 usb_endpoint_maxp(dev->interrupt_in_endpoint),
431 							 adu_interrupt_in_callback,
432 							 dev,
433 							 dev->interrupt_in_endpoint->bInterval);
434 					retval = usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
435 					if (retval) {
436 						dev->read_urb_finished = 1;
437 						if (retval == -ENOMEM) {
438 							retval = bytes_read ? bytes_read : -ENOMEM;
439 						}
440 						dev_dbg(&dev->udev->dev,
441 							"%s : submit failed\n",
442 							__func__);
443 						goto exit;
444 					}
445 				}
446 
447 				/* we wait for I/O to complete */
448 				set_current_state(TASK_INTERRUPTIBLE);
449 				add_wait_queue(&dev->read_wait, &wait);
450 				spin_lock_irqsave(&dev->buflock, flags);
451 				if (!dev->read_urb_finished) {
452 					spin_unlock_irqrestore(&dev->buflock, flags);
453 					timeout = schedule_timeout(COMMAND_TIMEOUT);
454 				} else {
455 					spin_unlock_irqrestore(&dev->buflock, flags);
456 					set_current_state(TASK_RUNNING);
457 				}
458 				remove_wait_queue(&dev->read_wait, &wait);
459 
460 				if (timeout <= 0) {
461 					dev_dbg(&dev->udev->dev,
462 						"%s : timeout\n", __func__);
463 					retval = bytes_read ? bytes_read : -ETIMEDOUT;
464 					goto exit;
465 				}
466 
467 				if (signal_pending(current)) {
468 					dev_dbg(&dev->udev->dev,
469 						"%s : signal pending\n",
470 						__func__);
471 					retval = bytes_read ? bytes_read : -EINTR;
472 					goto exit;
473 				}
474 			}
475 		}
476 	}
477 
478 	retval = bytes_read;
479 	/* if the primary buffer is empty then use it */
480 	spin_lock_irqsave(&dev->buflock, flags);
481 	if (should_submit && dev->read_urb_finished) {
482 		dev->read_urb_finished = 0;
483 		spin_unlock_irqrestore(&dev->buflock, flags);
484 		usb_fill_int_urb(dev->interrupt_in_urb, dev->udev,
485 				 usb_rcvintpipe(dev->udev,
486 					dev->interrupt_in_endpoint->bEndpointAddress),
487 				dev->interrupt_in_buffer,
488 				usb_endpoint_maxp(dev->interrupt_in_endpoint),
489 				adu_interrupt_in_callback,
490 				dev,
491 				dev->interrupt_in_endpoint->bInterval);
492 		if (usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL) != 0)
493 			dev->read_urb_finished = 1;
494 		/* we ignore failure */
495 	} else {
496 		spin_unlock_irqrestore(&dev->buflock, flags);
497 	}
498 
499 exit:
500 	/* unlock the device */
501 	mutex_unlock(&dev->mtx);
502 
503 	return retval;
504 }
505 
506 static ssize_t adu_write(struct file *file, const __user char *buffer,
507 			 size_t count, loff_t *ppos)
508 {
509 	DECLARE_WAITQUEUE(waita, current);
510 	struct adu_device *dev;
511 	size_t bytes_written = 0;
512 	size_t bytes_to_write;
513 	size_t buffer_size;
514 	unsigned long flags;
515 	int retval;
516 
517 	dev = file->private_data;
518 
519 	retval = mutex_lock_interruptible(&dev->mtx);
520 	if (retval)
521 		goto exit_nolock;
522 
523 	/* verify that the device wasn't unplugged */
524 	if (dev->udev == NULL) {
525 		retval = -ENODEV;
526 		pr_err("No device or device unplugged %d\n", retval);
527 		goto exit;
528 	}
529 
530 	/* verify that we actually have some data to write */
531 	if (count == 0) {
532 		dev_dbg(&dev->udev->dev, "%s : write request of 0 bytes\n",
533 			__func__);
534 		goto exit;
535 	}
536 
537 	while (count > 0) {
538 		add_wait_queue(&dev->write_wait, &waita);
539 		set_current_state(TASK_INTERRUPTIBLE);
540 		spin_lock_irqsave(&dev->buflock, flags);
541 		if (!dev->out_urb_finished) {
542 			spin_unlock_irqrestore(&dev->buflock, flags);
543 
544 			mutex_unlock(&dev->mtx);
545 			if (signal_pending(current)) {
546 				dev_dbg(&dev->udev->dev, "%s : interrupted\n",
547 					__func__);
548 				set_current_state(TASK_RUNNING);
549 				retval = -EINTR;
550 				goto exit_onqueue;
551 			}
552 			if (schedule_timeout(COMMAND_TIMEOUT) == 0) {
553 				dev_dbg(&dev->udev->dev,
554 					"%s - command timed out.\n", __func__);
555 				retval = -ETIMEDOUT;
556 				goto exit_onqueue;
557 			}
558 			remove_wait_queue(&dev->write_wait, &waita);
559 			retval = mutex_lock_interruptible(&dev->mtx);
560 			if (retval) {
561 				retval = bytes_written ? bytes_written : retval;
562 				goto exit_nolock;
563 			}
564 
565 			dev_dbg(&dev->udev->dev,
566 				"%s : in progress, count = %Zd\n",
567 				__func__, count);
568 		} else {
569 			spin_unlock_irqrestore(&dev->buflock, flags);
570 			set_current_state(TASK_RUNNING);
571 			remove_wait_queue(&dev->write_wait, &waita);
572 			dev_dbg(&dev->udev->dev, "%s : sending, count = %Zd\n",
573 				__func__, count);
574 
575 			/* write the data into interrupt_out_buffer from userspace */
576 			buffer_size = usb_endpoint_maxp(dev->interrupt_out_endpoint);
577 			bytes_to_write = count > buffer_size ? buffer_size : count;
578 			dev_dbg(&dev->udev->dev,
579 				"%s : buffer_size = %Zd, count = %Zd, bytes_to_write = %Zd\n",
580 				__func__, buffer_size, count, bytes_to_write);
581 
582 			if (copy_from_user(dev->interrupt_out_buffer, buffer, bytes_to_write) != 0) {
583 				retval = -EFAULT;
584 				goto exit;
585 			}
586 
587 			/* send off the urb */
588 			usb_fill_int_urb(
589 				dev->interrupt_out_urb,
590 				dev->udev,
591 				usb_sndintpipe(dev->udev, dev->interrupt_out_endpoint->bEndpointAddress),
592 				dev->interrupt_out_buffer,
593 				bytes_to_write,
594 				adu_interrupt_out_callback,
595 				dev,
596 				dev->interrupt_out_endpoint->bInterval);
597 			dev->interrupt_out_urb->actual_length = bytes_to_write;
598 			dev->out_urb_finished = 0;
599 			retval = usb_submit_urb(dev->interrupt_out_urb, GFP_KERNEL);
600 			if (retval < 0) {
601 				dev->out_urb_finished = 1;
602 				dev_err(&dev->udev->dev, "Couldn't submit "
603 					"interrupt_out_urb %d\n", retval);
604 				goto exit;
605 			}
606 
607 			buffer += bytes_to_write;
608 			count -= bytes_to_write;
609 
610 			bytes_written += bytes_to_write;
611 		}
612 	}
613 	mutex_unlock(&dev->mtx);
614 	return bytes_written;
615 
616 exit:
617 	mutex_unlock(&dev->mtx);
618 exit_nolock:
619 	return retval;
620 
621 exit_onqueue:
622 	remove_wait_queue(&dev->write_wait, &waita);
623 	return retval;
624 }
625 
626 /* file operations needed when we register this driver */
627 static const struct file_operations adu_fops = {
628 	.owner = THIS_MODULE,
629 	.read  = adu_read,
630 	.write = adu_write,
631 	.open = adu_open,
632 	.release = adu_release,
633 	.llseek = noop_llseek,
634 };
635 
636 /*
637  * usb class driver info in order to get a minor number from the usb core,
638  * and to have the device registered with devfs and the driver core
639  */
640 static struct usb_class_driver adu_class = {
641 	.name = "usb/adutux%d",
642 	.fops = &adu_fops,
643 	.minor_base = ADU_MINOR_BASE,
644 };
645 
646 /**
647  * adu_probe
648  *
649  * Called by the usb core when a new device is connected that it thinks
650  * this driver might be interested in.
651  */
652 static int adu_probe(struct usb_interface *interface,
653 		     const struct usb_device_id *id)
654 {
655 	struct usb_device *udev = interface_to_usbdev(interface);
656 	struct adu_device *dev = NULL;
657 	struct usb_host_interface *iface_desc;
658 	struct usb_endpoint_descriptor *endpoint;
659 	int retval = -ENODEV;
660 	int in_end_size;
661 	int out_end_size;
662 	int i;
663 
664 	if (udev == NULL) {
665 		dev_err(&interface->dev, "udev is NULL.\n");
666 		goto exit;
667 	}
668 
669 	/* allocate memory for our device state and initialize it */
670 	dev = kzalloc(sizeof(struct adu_device), GFP_KERNEL);
671 	if (!dev) {
672 		retval = -ENOMEM;
673 		goto exit;
674 	}
675 
676 	mutex_init(&dev->mtx);
677 	spin_lock_init(&dev->buflock);
678 	dev->udev = udev;
679 	init_waitqueue_head(&dev->read_wait);
680 	init_waitqueue_head(&dev->write_wait);
681 
682 	iface_desc = &interface->altsetting[0];
683 
684 	/* set up the endpoint information */
685 	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
686 		endpoint = &iface_desc->endpoint[i].desc;
687 
688 		if (usb_endpoint_is_int_in(endpoint))
689 			dev->interrupt_in_endpoint = endpoint;
690 
691 		if (usb_endpoint_is_int_out(endpoint))
692 			dev->interrupt_out_endpoint = endpoint;
693 	}
694 	if (dev->interrupt_in_endpoint == NULL) {
695 		dev_err(&interface->dev, "interrupt in endpoint not found\n");
696 		goto error;
697 	}
698 	if (dev->interrupt_out_endpoint == NULL) {
699 		dev_err(&interface->dev, "interrupt out endpoint not found\n");
700 		goto error;
701 	}
702 
703 	in_end_size = usb_endpoint_maxp(dev->interrupt_in_endpoint);
704 	out_end_size = usb_endpoint_maxp(dev->interrupt_out_endpoint);
705 
706 	dev->read_buffer_primary = kmalloc((4 * in_end_size), GFP_KERNEL);
707 	if (!dev->read_buffer_primary) {
708 		retval = -ENOMEM;
709 		goto error;
710 	}
711 
712 	/* debug code prime the buffer */
713 	memset(dev->read_buffer_primary, 'a', in_end_size);
714 	memset(dev->read_buffer_primary + in_end_size, 'b', in_end_size);
715 	memset(dev->read_buffer_primary + (2 * in_end_size), 'c', in_end_size);
716 	memset(dev->read_buffer_primary + (3 * in_end_size), 'd', in_end_size);
717 
718 	dev->read_buffer_secondary = kmalloc((4 * in_end_size), GFP_KERNEL);
719 	if (!dev->read_buffer_secondary) {
720 		retval = -ENOMEM;
721 		goto error;
722 	}
723 
724 	/* debug code prime the buffer */
725 	memset(dev->read_buffer_secondary, 'e', in_end_size);
726 	memset(dev->read_buffer_secondary + in_end_size, 'f', in_end_size);
727 	memset(dev->read_buffer_secondary + (2 * in_end_size), 'g', in_end_size);
728 	memset(dev->read_buffer_secondary + (3 * in_end_size), 'h', in_end_size);
729 
730 	dev->interrupt_in_buffer = kmalloc(in_end_size, GFP_KERNEL);
731 	if (!dev->interrupt_in_buffer)
732 		goto error;
733 
734 	/* debug code prime the buffer */
735 	memset(dev->interrupt_in_buffer, 'i', in_end_size);
736 
737 	dev->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
738 	if (!dev->interrupt_in_urb)
739 		goto error;
740 	dev->interrupt_out_buffer = kmalloc(out_end_size, GFP_KERNEL);
741 	if (!dev->interrupt_out_buffer)
742 		goto error;
743 	dev->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
744 	if (!dev->interrupt_out_urb)
745 		goto error;
746 
747 	if (!usb_string(udev, udev->descriptor.iSerialNumber, dev->serial_number,
748 			sizeof(dev->serial_number))) {
749 		dev_err(&interface->dev, "Could not retrieve serial number\n");
750 		goto error;
751 	}
752 	dev_dbg(&interface->dev,"serial_number=%s", dev->serial_number);
753 
754 	/* we can register the device now, as it is ready */
755 	usb_set_intfdata(interface, dev);
756 
757 	retval = usb_register_dev(interface, &adu_class);
758 
759 	if (retval) {
760 		/* something prevented us from registering this driver */
761 		dev_err(&interface->dev, "Not able to get a minor for this device.\n");
762 		usb_set_intfdata(interface, NULL);
763 		goto error;
764 	}
765 
766 	dev->minor = interface->minor;
767 
768 	/* let the user know what node this device is now attached to */
769 	dev_info(&interface->dev, "ADU%d %s now attached to /dev/usb/adutux%d\n",
770 		 le16_to_cpu(udev->descriptor.idProduct), dev->serial_number,
771 		 (dev->minor - ADU_MINOR_BASE));
772 exit:
773 	return retval;
774 
775 error:
776 	adu_delete(dev);
777 	return retval;
778 }
779 
780 /**
781  * adu_disconnect
782  *
783  * Called by the usb core when the device is removed from the system.
784  */
785 static void adu_disconnect(struct usb_interface *interface)
786 {
787 	struct adu_device *dev;
788 	int minor;
789 
790 	dev = usb_get_intfdata(interface);
791 
792 	mutex_lock(&dev->mtx);	/* not interruptible */
793 	dev->udev = NULL;	/* poison */
794 	minor = dev->minor;
795 	usb_deregister_dev(interface, &adu_class);
796 	mutex_unlock(&dev->mtx);
797 
798 	mutex_lock(&adutux_mutex);
799 	usb_set_intfdata(interface, NULL);
800 
801 	/* if the device is not opened, then we clean up right now */
802 	if (!dev->open_count)
803 		adu_delete(dev);
804 
805 	mutex_unlock(&adutux_mutex);
806 }
807 
808 /* usb specific object needed to register this driver with the usb subsystem */
809 static struct usb_driver adu_driver = {
810 	.name = "adutux",
811 	.probe = adu_probe,
812 	.disconnect = adu_disconnect,
813 	.id_table = device_table,
814 };
815 
816 module_usb_driver(adu_driver);
817 
818 MODULE_AUTHOR(DRIVER_AUTHOR);
819 MODULE_DESCRIPTION(DRIVER_DESC);
820 MODULE_LICENSE("GPL");
821