xref: /linux/drivers/usb/misc/adutux.c (revision 148f9bb87745ed45f7a11b2cbd3bc0f017d5d257)
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 #include <linux/kernel.h>
22 #include <linux/errno.h>
23 #include <linux/init.h>
24 #include <linux/slab.h>
25 #include <linux/module.h>
26 #include <linux/usb.h>
27 #include <linux/mutex.h>
28 #include <linux/uaccess.h>
29 
30 #ifdef CONFIG_USB_DEBUG
31 static int debug = 5;
32 #else
33 static int debug = 1;
34 #endif
35 
36 /* Use our own dbg macro */
37 #undef dbg
38 #define dbg(lvl, format, arg...)	\
39 do {								\
40 	if (debug >= lvl)						\
41 		printk(KERN_DEBUG "%s: " format "\n", __FILE__, ##arg);	\
42 } while (0)
43 
44 
45 /* Version Information */
46 #define DRIVER_VERSION "v0.0.13"
47 #define DRIVER_AUTHOR "John Homppi"
48 #define DRIVER_DESC "adutux (see www.ontrak.net)"
49 
50 /* Module parameters */
51 module_param(debug, int, S_IRUGO | S_IWUSR);
52 MODULE_PARM_DESC(debug, "Debug enabled or not");
53 
54 /* Define these values to match your device */
55 #define ADU_VENDOR_ID 0x0a07
56 #define ADU_PRODUCT_ID 0x0064
57 
58 /* table of devices that work with this driver */
59 static const struct usb_device_id device_table[] = {
60 	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID) },		/* ADU100 */
61 	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID+20) },	/* ADU120 */
62 	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID+30) },	/* ADU130 */
63 	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID+100) },	/* ADU200 */
64 	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID+108) },	/* ADU208 */
65 	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID+118) },	/* ADU218 */
66 	{ } /* Terminating entry */
67 };
68 
69 MODULE_DEVICE_TABLE(usb, device_table);
70 
71 #ifdef CONFIG_USB_DYNAMIC_MINORS
72 #define ADU_MINOR_BASE	0
73 #else
74 #define ADU_MINOR_BASE	67
75 #endif
76 
77 /* we can have up to this number of device plugged in at once */
78 #define MAX_DEVICES	16
79 
80 #define COMMAND_TIMEOUT	(2*HZ)	/* 60 second timeout for a command */
81 
82 /*
83  * The locking scheme is a vanilla 3-lock:
84  *   adu_device.buflock: A spinlock, covers what IRQs touch.
85  *   adutux_mutex:       A Static lock to cover open_count. It would also cover
86  *                       any globals, but we don't have them in 2.6.
87  *   adu_device.mtx:     A mutex to hold across sleepers like copy_from_user.
88  *                       It covers all of adu_device, except the open_count
89  *                       and what .buflock covers.
90  */
91 
92 /* Structure to hold all of our device specific stuff */
93 struct adu_device {
94 	struct mutex		mtx;
95 	struct usb_device *udev; /* save off the usb device pointer */
96 	struct usb_interface *interface;
97 	unsigned int		minor; /* the starting minor number for this device */
98 	char			serial_number[8];
99 
100 	int			open_count; /* number of times this port has been opened */
101 
102 	char		*read_buffer_primary;
103 	int			read_buffer_length;
104 	char		*read_buffer_secondary;
105 	int			secondary_head;
106 	int			secondary_tail;
107 	spinlock_t		buflock;
108 
109 	wait_queue_head_t	read_wait;
110 	wait_queue_head_t	write_wait;
111 
112 	char		*interrupt_in_buffer;
113 	struct usb_endpoint_descriptor *interrupt_in_endpoint;
114 	struct urb	*interrupt_in_urb;
115 	int			read_urb_finished;
116 
117 	char		*interrupt_out_buffer;
118 	struct usb_endpoint_descriptor *interrupt_out_endpoint;
119 	struct urb	*interrupt_out_urb;
120 	int			out_urb_finished;
121 };
122 
123 static DEFINE_MUTEX(adutux_mutex);
124 
125 static struct usb_driver adu_driver;
126 
127 static void adu_debug_data(int level, const char *function, int size,
128 			   const unsigned char *data)
129 {
130 	int i;
131 
132 	if (debug < level)
133 		return;
134 
135 	printk(KERN_DEBUG "%s: %s - length = %d, data = ",
136 	       __FILE__, function, size);
137 	for (i = 0; i < size; ++i)
138 		printk("%.2x ", data[i]);
139 	printk("\n");
140 }
141 
142 /**
143  * adu_abort_transfers
144  *      aborts transfers and frees associated data structures
145  */
146 static void adu_abort_transfers(struct adu_device *dev)
147 {
148 	unsigned long flags;
149 
150 	dbg(2, " %s : enter", __func__);
151 
152 	if (dev->udev == NULL) {
153 		dbg(1, " %s : udev is null", __func__);
154 		goto exit;
155 	}
156 
157 	/* shutdown transfer */
158 
159 	/* XXX Anchor these instead */
160 	spin_lock_irqsave(&dev->buflock, flags);
161 	if (!dev->read_urb_finished) {
162 		spin_unlock_irqrestore(&dev->buflock, flags);
163 		usb_kill_urb(dev->interrupt_in_urb);
164 	} else
165 		spin_unlock_irqrestore(&dev->buflock, flags);
166 
167 	spin_lock_irqsave(&dev->buflock, flags);
168 	if (!dev->out_urb_finished) {
169 		spin_unlock_irqrestore(&dev->buflock, flags);
170 		usb_kill_urb(dev->interrupt_out_urb);
171 	} else
172 		spin_unlock_irqrestore(&dev->buflock, flags);
173 
174 exit:
175 	dbg(2, " %s : leave", __func__);
176 }
177 
178 static void adu_delete(struct adu_device *dev)
179 {
180 	dbg(2, "%s enter", __func__);
181 
182 	/* free data structures */
183 	usb_free_urb(dev->interrupt_in_urb);
184 	usb_free_urb(dev->interrupt_out_urb);
185 	kfree(dev->read_buffer_primary);
186 	kfree(dev->read_buffer_secondary);
187 	kfree(dev->interrupt_in_buffer);
188 	kfree(dev->interrupt_out_buffer);
189 	kfree(dev);
190 
191 	dbg(2, "%s : leave", __func__);
192 }
193 
194 static void adu_interrupt_in_callback(struct urb *urb)
195 {
196 	struct adu_device *dev = urb->context;
197 	int status = urb->status;
198 
199 	dbg(4, " %s : enter, status %d", __func__, status);
200 	adu_debug_data(5, __func__, urb->actual_length,
201 		       urb->transfer_buffer);
202 
203 	spin_lock(&dev->buflock);
204 
205 	if (status != 0) {
206 		if ((status != -ENOENT) && (status != -ECONNRESET) &&
207 			(status != -ESHUTDOWN)) {
208 			dbg(1, " %s : nonzero status received: %d",
209 			    __func__, status);
210 		}
211 		goto exit;
212 	}
213 
214 	if (urb->actual_length > 0 && dev->interrupt_in_buffer[0] != 0x00) {
215 		if (dev->read_buffer_length <
216 		    (4 * usb_endpoint_maxp(dev->interrupt_in_endpoint)) -
217 		     (urb->actual_length)) {
218 			memcpy (dev->read_buffer_primary +
219 				dev->read_buffer_length,
220 				dev->interrupt_in_buffer, urb->actual_length);
221 
222 			dev->read_buffer_length += urb->actual_length;
223 			dbg(2, " %s reading  %d ", __func__,
224 			    urb->actual_length);
225 		} else {
226 			dbg(1, " %s : read_buffer overflow", __func__);
227 		}
228 	}
229 
230 exit:
231 	dev->read_urb_finished = 1;
232 	spin_unlock(&dev->buflock);
233 	/* always wake up so we recover from errors */
234 	wake_up_interruptible(&dev->read_wait);
235 	adu_debug_data(5, __func__, urb->actual_length,
236 		       urb->transfer_buffer);
237 	dbg(4, " %s : leave, status %d", __func__, status);
238 }
239 
240 static void adu_interrupt_out_callback(struct urb *urb)
241 {
242 	struct adu_device *dev = urb->context;
243 	int status = urb->status;
244 
245 	dbg(4, " %s : enter, status %d", __func__, status);
246 	adu_debug_data(5, __func__, urb->actual_length, urb->transfer_buffer);
247 
248 	if (status != 0) {
249 		if ((status != -ENOENT) &&
250 		    (status != -ECONNRESET)) {
251 			dbg(1, " %s :nonzero status received: %d",
252 			    __func__, status);
253 		}
254 		goto exit;
255 	}
256 
257 	spin_lock(&dev->buflock);
258 	dev->out_urb_finished = 1;
259 	wake_up(&dev->write_wait);
260 	spin_unlock(&dev->buflock);
261 exit:
262 
263 	adu_debug_data(5, __func__, urb->actual_length,
264 		       urb->transfer_buffer);
265 	dbg(4, " %s : leave, status %d", __func__, status);
266 }
267 
268 static int adu_open(struct inode *inode, struct file *file)
269 {
270 	struct adu_device *dev = NULL;
271 	struct usb_interface *interface;
272 	int subminor;
273 	int retval;
274 
275 	dbg(2, "%s : enter", __func__);
276 
277 	subminor = iminor(inode);
278 
279 	retval = mutex_lock_interruptible(&adutux_mutex);
280 	if (retval) {
281 		dbg(2, "%s : mutex lock failed", __func__);
282 		goto exit_no_lock;
283 	}
284 
285 	interface = usb_find_interface(&adu_driver, subminor);
286 	if (!interface) {
287 		printk(KERN_ERR "adutux: %s - error, can't find device for "
288 		       "minor %d\n", __func__, subminor);
289 		retval = -ENODEV;
290 		goto exit_no_device;
291 	}
292 
293 	dev = usb_get_intfdata(interface);
294 	if (!dev || !dev->udev) {
295 		retval = -ENODEV;
296 		goto exit_no_device;
297 	}
298 
299 	/* check that nobody else is using the device */
300 	if (dev->open_count) {
301 		retval = -EBUSY;
302 		goto exit_no_device;
303 	}
304 
305 	++dev->open_count;
306 	dbg(2, "%s : open count %d", __func__, dev->open_count);
307 
308 	/* save device in the file's private structure */
309 	file->private_data = dev;
310 
311 	/* initialize in direction */
312 	dev->read_buffer_length = 0;
313 
314 	/* fixup first read by having urb waiting for it */
315 	usb_fill_int_urb(dev->interrupt_in_urb, dev->udev,
316 			 usb_rcvintpipe(dev->udev,
317 					dev->interrupt_in_endpoint->bEndpointAddress),
318 			 dev->interrupt_in_buffer,
319 			 usb_endpoint_maxp(dev->interrupt_in_endpoint),
320 			 adu_interrupt_in_callback, dev,
321 			 dev->interrupt_in_endpoint->bInterval);
322 	dev->read_urb_finished = 0;
323 	if (usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL))
324 		dev->read_urb_finished = 1;
325 	/* we ignore failure */
326 	/* end of fixup for first read */
327 
328 	/* initialize out direction */
329 	dev->out_urb_finished = 1;
330 
331 	retval = 0;
332 
333 exit_no_device:
334 	mutex_unlock(&adutux_mutex);
335 exit_no_lock:
336 	dbg(2, "%s : leave, return value %d ", __func__, retval);
337 	return retval;
338 }
339 
340 static void adu_release_internal(struct adu_device *dev)
341 {
342 	dbg(2, " %s : enter", __func__);
343 
344 	/* decrement our usage count for the device */
345 	--dev->open_count;
346 	dbg(2, " %s : open count %d", __func__, dev->open_count);
347 	if (dev->open_count <= 0) {
348 		adu_abort_transfers(dev);
349 		dev->open_count = 0;
350 	}
351 
352 	dbg(2, " %s : leave", __func__);
353 }
354 
355 static int adu_release(struct inode *inode, struct file *file)
356 {
357 	struct adu_device *dev;
358 	int retval = 0;
359 
360 	dbg(2, " %s : enter", __func__);
361 
362 	if (file == NULL) {
363 		dbg(1, " %s : file is NULL", __func__);
364 		retval = -ENODEV;
365 		goto exit;
366 	}
367 
368 	dev = file->private_data;
369 	if (dev == NULL) {
370 		dbg(1, " %s : object is NULL", __func__);
371 		retval = -ENODEV;
372 		goto exit;
373 	}
374 
375 	mutex_lock(&adutux_mutex); /* not interruptible */
376 
377 	if (dev->open_count <= 0) {
378 		dbg(1, " %s : device not opened", __func__);
379 		retval = -ENODEV;
380 		goto unlock;
381 	}
382 
383 	adu_release_internal(dev);
384 	if (dev->udev == NULL) {
385 		/* the device was unplugged before the file was released */
386 		if (!dev->open_count)	/* ... and we're the last user */
387 			adu_delete(dev);
388 	}
389 unlock:
390 	mutex_unlock(&adutux_mutex);
391 exit:
392 	dbg(2, " %s : leave, return value %d", __func__, retval);
393 	return retval;
394 }
395 
396 static ssize_t adu_read(struct file *file, __user char *buffer, size_t count,
397 			loff_t *ppos)
398 {
399 	struct adu_device *dev;
400 	size_t bytes_read = 0;
401 	size_t bytes_to_read = count;
402 	int i;
403 	int retval = 0;
404 	int timeout = 0;
405 	int should_submit = 0;
406 	unsigned long flags;
407 	DECLARE_WAITQUEUE(wait, current);
408 
409 	dbg(2, " %s : enter, count = %Zd, file=%p", __func__, count, file);
410 
411 	dev = file->private_data;
412 	dbg(2, " %s : dev=%p", __func__, dev);
413 
414 	if (mutex_lock_interruptible(&dev->mtx))
415 		return -ERESTARTSYS;
416 
417 	/* verify that the device wasn't unplugged */
418 	if (dev->udev == NULL) {
419 		retval = -ENODEV;
420 		printk(KERN_ERR "adutux: No device or device unplugged %d\n",
421 		       retval);
422 		goto exit;
423 	}
424 
425 	/* verify that some data was requested */
426 	if (count == 0) {
427 		dbg(1, " %s : read request of 0 bytes", __func__);
428 		goto exit;
429 	}
430 
431 	timeout = COMMAND_TIMEOUT;
432 	dbg(2, " %s : about to start looping", __func__);
433 	while (bytes_to_read) {
434 		int data_in_secondary = dev->secondary_tail - dev->secondary_head;
435 		dbg(2, " %s : while, data_in_secondary=%d, status=%d",
436 		    __func__, data_in_secondary,
437 		    dev->interrupt_in_urb->status);
438 
439 		if (data_in_secondary) {
440 			/* drain secondary buffer */
441 			int amount = bytes_to_read < data_in_secondary ? bytes_to_read : data_in_secondary;
442 			i = copy_to_user(buffer, dev->read_buffer_secondary+dev->secondary_head, amount);
443 			if (i) {
444 				retval = -EFAULT;
445 				goto exit;
446 			}
447 			dev->secondary_head += (amount - i);
448 			bytes_read += (amount - i);
449 			bytes_to_read -= (amount - i);
450 			if (i) {
451 				retval = bytes_read ? bytes_read : -EFAULT;
452 				goto exit;
453 			}
454 		} else {
455 			/* we check the primary buffer */
456 			spin_lock_irqsave (&dev->buflock, flags);
457 			if (dev->read_buffer_length) {
458 				/* we secure access to the primary */
459 				char *tmp;
460 				dbg(2, " %s : swap, read_buffer_length = %d",
461 				    __func__, dev->read_buffer_length);
462 				tmp = dev->read_buffer_secondary;
463 				dev->read_buffer_secondary = dev->read_buffer_primary;
464 				dev->read_buffer_primary = tmp;
465 				dev->secondary_head = 0;
466 				dev->secondary_tail = dev->read_buffer_length;
467 				dev->read_buffer_length = 0;
468 				spin_unlock_irqrestore(&dev->buflock, flags);
469 				/* we have a free buffer so use it */
470 				should_submit = 1;
471 			} else {
472 				/* even the primary was empty - we may need to do IO */
473 				if (!dev->read_urb_finished) {
474 					/* somebody is doing IO */
475 					spin_unlock_irqrestore(&dev->buflock, flags);
476 					dbg(2, " %s : submitted already", __func__);
477 				} else {
478 					/* we must initiate input */
479 					dbg(2, " %s : initiate input", __func__);
480 					dev->read_urb_finished = 0;
481 					spin_unlock_irqrestore(&dev->buflock, flags);
482 
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 					retval = usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
492 					if (retval) {
493 						dev->read_urb_finished = 1;
494 						if (retval == -ENOMEM) {
495 							retval = bytes_read ? bytes_read : -ENOMEM;
496 						}
497 						dbg(2, " %s : submit failed", __func__);
498 						goto exit;
499 					}
500 				}
501 
502 				/* we wait for I/O to complete */
503 				set_current_state(TASK_INTERRUPTIBLE);
504 				add_wait_queue(&dev->read_wait, &wait);
505 				spin_lock_irqsave(&dev->buflock, flags);
506 				if (!dev->read_urb_finished) {
507 					spin_unlock_irqrestore(&dev->buflock, flags);
508 					timeout = schedule_timeout(COMMAND_TIMEOUT);
509 				} else {
510 					spin_unlock_irqrestore(&dev->buflock, flags);
511 					set_current_state(TASK_RUNNING);
512 				}
513 				remove_wait_queue(&dev->read_wait, &wait);
514 
515 				if (timeout <= 0) {
516 					dbg(2, " %s : timeout", __func__);
517 					retval = bytes_read ? bytes_read : -ETIMEDOUT;
518 					goto exit;
519 				}
520 
521 				if (signal_pending(current)) {
522 					dbg(2, " %s : signal pending", __func__);
523 					retval = bytes_read ? bytes_read : -EINTR;
524 					goto exit;
525 				}
526 			}
527 		}
528 	}
529 
530 	retval = bytes_read;
531 	/* if the primary buffer is empty then use it */
532 	spin_lock_irqsave(&dev->buflock, flags);
533 	if (should_submit && dev->read_urb_finished) {
534 		dev->read_urb_finished = 0;
535 		spin_unlock_irqrestore(&dev->buflock, flags);
536 		usb_fill_int_urb(dev->interrupt_in_urb, dev->udev,
537 				 usb_rcvintpipe(dev->udev,
538 					dev->interrupt_in_endpoint->bEndpointAddress),
539 				dev->interrupt_in_buffer,
540 				usb_endpoint_maxp(dev->interrupt_in_endpoint),
541 				adu_interrupt_in_callback,
542 				dev,
543 				dev->interrupt_in_endpoint->bInterval);
544 		if (usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL) != 0)
545 			dev->read_urb_finished = 1;
546 		/* we ignore failure */
547 	} else {
548 		spin_unlock_irqrestore(&dev->buflock, flags);
549 	}
550 
551 exit:
552 	/* unlock the device */
553 	mutex_unlock(&dev->mtx);
554 
555 	dbg(2, " %s : leave, return value %d", __func__, retval);
556 	return retval;
557 }
558 
559 static ssize_t adu_write(struct file *file, const __user char *buffer,
560 			 size_t count, loff_t *ppos)
561 {
562 	DECLARE_WAITQUEUE(waita, current);
563 	struct adu_device *dev;
564 	size_t bytes_written = 0;
565 	size_t bytes_to_write;
566 	size_t buffer_size;
567 	unsigned long flags;
568 	int retval;
569 
570 	dbg(2, " %s : enter, count = %Zd", __func__, count);
571 
572 	dev = file->private_data;
573 
574 	retval = mutex_lock_interruptible(&dev->mtx);
575 	if (retval)
576 		goto exit_nolock;
577 
578 	/* verify that the device wasn't unplugged */
579 	if (dev->udev == NULL) {
580 		retval = -ENODEV;
581 		printk(KERN_ERR "adutux: No device or device unplugged %d\n",
582 		       retval);
583 		goto exit;
584 	}
585 
586 	/* verify that we actually have some data to write */
587 	if (count == 0) {
588 		dbg(1, " %s : write request of 0 bytes", __func__);
589 		goto exit;
590 	}
591 
592 	while (count > 0) {
593 		add_wait_queue(&dev->write_wait, &waita);
594 		set_current_state(TASK_INTERRUPTIBLE);
595 		spin_lock_irqsave(&dev->buflock, flags);
596 		if (!dev->out_urb_finished) {
597 			spin_unlock_irqrestore(&dev->buflock, flags);
598 
599 			mutex_unlock(&dev->mtx);
600 			if (signal_pending(current)) {
601 				dbg(1, " %s : interrupted", __func__);
602 				set_current_state(TASK_RUNNING);
603 				retval = -EINTR;
604 				goto exit_onqueue;
605 			}
606 			if (schedule_timeout(COMMAND_TIMEOUT) == 0) {
607 				dbg(1, "%s - command timed out.", __func__);
608 				retval = -ETIMEDOUT;
609 				goto exit_onqueue;
610 			}
611 			remove_wait_queue(&dev->write_wait, &waita);
612 			retval = mutex_lock_interruptible(&dev->mtx);
613 			if (retval) {
614 				retval = bytes_written ? bytes_written : retval;
615 				goto exit_nolock;
616 			}
617 
618 			dbg(4, " %s : in progress, count = %Zd", __func__, count);
619 		} else {
620 			spin_unlock_irqrestore(&dev->buflock, flags);
621 			set_current_state(TASK_RUNNING);
622 			remove_wait_queue(&dev->write_wait, &waita);
623 			dbg(4, " %s : sending, count = %Zd", __func__, count);
624 
625 			/* write the data into interrupt_out_buffer from userspace */
626 			buffer_size = usb_endpoint_maxp(dev->interrupt_out_endpoint);
627 			bytes_to_write = count > buffer_size ? buffer_size : count;
628 			dbg(4, " %s : buffer_size = %Zd, count = %Zd, bytes_to_write = %Zd",
629 			    __func__, buffer_size, count, bytes_to_write);
630 
631 			if (copy_from_user(dev->interrupt_out_buffer, buffer, bytes_to_write) != 0) {
632 				retval = -EFAULT;
633 				goto exit;
634 			}
635 
636 			/* send off the urb */
637 			usb_fill_int_urb(
638 				dev->interrupt_out_urb,
639 				dev->udev,
640 				usb_sndintpipe(dev->udev, dev->interrupt_out_endpoint->bEndpointAddress),
641 				dev->interrupt_out_buffer,
642 				bytes_to_write,
643 				adu_interrupt_out_callback,
644 				dev,
645 				dev->interrupt_out_endpoint->bInterval);
646 			dev->interrupt_out_urb->actual_length = bytes_to_write;
647 			dev->out_urb_finished = 0;
648 			retval = usb_submit_urb(dev->interrupt_out_urb, GFP_KERNEL);
649 			if (retval < 0) {
650 				dev->out_urb_finished = 1;
651 				dev_err(&dev->udev->dev, "Couldn't submit "
652 					"interrupt_out_urb %d\n", retval);
653 				goto exit;
654 			}
655 
656 			buffer += bytes_to_write;
657 			count -= bytes_to_write;
658 
659 			bytes_written += bytes_to_write;
660 		}
661 	}
662 	mutex_unlock(&dev->mtx);
663 	return bytes_written;
664 
665 exit:
666 	mutex_unlock(&dev->mtx);
667 exit_nolock:
668 	dbg(2, " %s : leave, return value %d", __func__, retval);
669 	return retval;
670 
671 exit_onqueue:
672 	remove_wait_queue(&dev->write_wait, &waita);
673 	return retval;
674 }
675 
676 /* file operations needed when we register this driver */
677 static const struct file_operations adu_fops = {
678 	.owner = THIS_MODULE,
679 	.read  = adu_read,
680 	.write = adu_write,
681 	.open = adu_open,
682 	.release = adu_release,
683 	.llseek = noop_llseek,
684 };
685 
686 /*
687  * usb class driver info in order to get a minor number from the usb core,
688  * and to have the device registered with devfs and the driver core
689  */
690 static struct usb_class_driver adu_class = {
691 	.name = "usb/adutux%d",
692 	.fops = &adu_fops,
693 	.minor_base = ADU_MINOR_BASE,
694 };
695 
696 /**
697  * adu_probe
698  *
699  * Called by the usb core when a new device is connected that it thinks
700  * this driver might be interested in.
701  */
702 static int adu_probe(struct usb_interface *interface,
703 		     const struct usb_device_id *id)
704 {
705 	struct usb_device *udev = interface_to_usbdev(interface);
706 	struct adu_device *dev = NULL;
707 	struct usb_host_interface *iface_desc;
708 	struct usb_endpoint_descriptor *endpoint;
709 	int retval = -ENODEV;
710 	int in_end_size;
711 	int out_end_size;
712 	int i;
713 
714 	dbg(2, " %s : enter", __func__);
715 
716 	if (udev == NULL) {
717 		dev_err(&interface->dev, "udev is NULL.\n");
718 		goto exit;
719 	}
720 
721 	/* allocate memory for our device state and initialize it */
722 	dev = kzalloc(sizeof(struct adu_device), GFP_KERNEL);
723 	if (dev == NULL) {
724 		dev_err(&interface->dev, "Out of memory\n");
725 		retval = -ENOMEM;
726 		goto exit;
727 	}
728 
729 	mutex_init(&dev->mtx);
730 	spin_lock_init(&dev->buflock);
731 	dev->udev = udev;
732 	init_waitqueue_head(&dev->read_wait);
733 	init_waitqueue_head(&dev->write_wait);
734 
735 	iface_desc = &interface->altsetting[0];
736 
737 	/* set up the endpoint information */
738 	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
739 		endpoint = &iface_desc->endpoint[i].desc;
740 
741 		if (usb_endpoint_is_int_in(endpoint))
742 			dev->interrupt_in_endpoint = endpoint;
743 
744 		if (usb_endpoint_is_int_out(endpoint))
745 			dev->interrupt_out_endpoint = endpoint;
746 	}
747 	if (dev->interrupt_in_endpoint == NULL) {
748 		dev_err(&interface->dev, "interrupt in endpoint not found\n");
749 		goto error;
750 	}
751 	if (dev->interrupt_out_endpoint == NULL) {
752 		dev_err(&interface->dev, "interrupt out endpoint not found\n");
753 		goto error;
754 	}
755 
756 	in_end_size = usb_endpoint_maxp(dev->interrupt_in_endpoint);
757 	out_end_size = usb_endpoint_maxp(dev->interrupt_out_endpoint);
758 
759 	dev->read_buffer_primary = kmalloc((4 * in_end_size), GFP_KERNEL);
760 	if (!dev->read_buffer_primary) {
761 		dev_err(&interface->dev, "Couldn't allocate read_buffer_primary\n");
762 		retval = -ENOMEM;
763 		goto error;
764 	}
765 
766 	/* debug code prime the buffer */
767 	memset(dev->read_buffer_primary, 'a', in_end_size);
768 	memset(dev->read_buffer_primary + in_end_size, 'b', in_end_size);
769 	memset(dev->read_buffer_primary + (2 * in_end_size), 'c', in_end_size);
770 	memset(dev->read_buffer_primary + (3 * in_end_size), 'd', in_end_size);
771 
772 	dev->read_buffer_secondary = kmalloc((4 * in_end_size), GFP_KERNEL);
773 	if (!dev->read_buffer_secondary) {
774 		dev_err(&interface->dev, "Couldn't allocate read_buffer_secondary\n");
775 		retval = -ENOMEM;
776 		goto error;
777 	}
778 
779 	/* debug code prime the buffer */
780 	memset(dev->read_buffer_secondary, 'e', in_end_size);
781 	memset(dev->read_buffer_secondary + in_end_size, 'f', in_end_size);
782 	memset(dev->read_buffer_secondary + (2 * in_end_size), 'g', in_end_size);
783 	memset(dev->read_buffer_secondary + (3 * in_end_size), 'h', in_end_size);
784 
785 	dev->interrupt_in_buffer = kmalloc(in_end_size, GFP_KERNEL);
786 	if (!dev->interrupt_in_buffer) {
787 		dev_err(&interface->dev, "Couldn't allocate interrupt_in_buffer\n");
788 		goto error;
789 	}
790 
791 	/* debug code prime the buffer */
792 	memset(dev->interrupt_in_buffer, 'i', in_end_size);
793 
794 	dev->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
795 	if (!dev->interrupt_in_urb) {
796 		dev_err(&interface->dev, "Couldn't allocate interrupt_in_urb\n");
797 		goto error;
798 	}
799 	dev->interrupt_out_buffer = kmalloc(out_end_size, GFP_KERNEL);
800 	if (!dev->interrupt_out_buffer) {
801 		dev_err(&interface->dev, "Couldn't allocate interrupt_out_buffer\n");
802 		goto error;
803 	}
804 	dev->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
805 	if (!dev->interrupt_out_urb) {
806 		dev_err(&interface->dev, "Couldn't allocate interrupt_out_urb\n");
807 		goto error;
808 	}
809 
810 	if (!usb_string(udev, udev->descriptor.iSerialNumber, dev->serial_number,
811 			sizeof(dev->serial_number))) {
812 		dev_err(&interface->dev, "Could not retrieve serial number\n");
813 		goto error;
814 	}
815 	dbg(2, " %s : serial_number=%s", __func__, dev->serial_number);
816 
817 	/* we can register the device now, as it is ready */
818 	usb_set_intfdata(interface, dev);
819 
820 	retval = usb_register_dev(interface, &adu_class);
821 
822 	if (retval) {
823 		/* something prevented us from registering this driver */
824 		dev_err(&interface->dev, "Not able to get a minor for this device.\n");
825 		usb_set_intfdata(interface, NULL);
826 		goto error;
827 	}
828 
829 	dev->minor = interface->minor;
830 
831 	/* let the user know what node this device is now attached to */
832 	dev_info(&interface->dev, "ADU%d %s now attached to /dev/usb/adutux%d\n",
833 		 udev->descriptor.idProduct, dev->serial_number,
834 		 (dev->minor - ADU_MINOR_BASE));
835 exit:
836 	dbg(2, " %s : leave, return value %p (dev)", __func__, dev);
837 
838 	return retval;
839 
840 error:
841 	adu_delete(dev);
842 	return retval;
843 }
844 
845 /**
846  * adu_disconnect
847  *
848  * Called by the usb core when the device is removed from the system.
849  */
850 static void adu_disconnect(struct usb_interface *interface)
851 {
852 	struct adu_device *dev;
853 	int minor;
854 
855 	dbg(2, " %s : enter", __func__);
856 
857 	dev = usb_get_intfdata(interface);
858 
859 	mutex_lock(&dev->mtx);	/* not interruptible */
860 	dev->udev = NULL;	/* poison */
861 	minor = dev->minor;
862 	usb_deregister_dev(interface, &adu_class);
863 	mutex_unlock(&dev->mtx);
864 
865 	mutex_lock(&adutux_mutex);
866 	usb_set_intfdata(interface, NULL);
867 
868 	/* if the device is not opened, then we clean up right now */
869 	dbg(2, " %s : open count %d", __func__, dev->open_count);
870 	if (!dev->open_count)
871 		adu_delete(dev);
872 
873 	mutex_unlock(&adutux_mutex);
874 
875 	dev_info(&interface->dev, "ADU device adutux%d now disconnected\n",
876 		 (minor - ADU_MINOR_BASE));
877 
878 	dbg(2, " %s : leave", __func__);
879 }
880 
881 /* usb specific object needed to register this driver with the usb subsystem */
882 static struct usb_driver adu_driver = {
883 	.name = "adutux",
884 	.probe = adu_probe,
885 	.disconnect = adu_disconnect,
886 	.id_table = device_table,
887 };
888 
889 module_usb_driver(adu_driver);
890 
891 MODULE_AUTHOR(DRIVER_AUTHOR);
892 MODULE_DESCRIPTION(DRIVER_DESC);
893 MODULE_LICENSE("GPL");
894