xref: /openbmc/linux/drivers/usb/misc/adutux.c (revision 4800cd83)
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 <asm/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 * le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize)) -
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 	if ((retval = mutex_lock_interruptible(&adutux_mutex))) {
280 		dbg(2, "%s : mutex lock failed", __func__);
281 		goto exit_no_lock;
282 	}
283 
284 	interface = usb_find_interface(&adu_driver, subminor);
285 	if (!interface) {
286 		printk(KERN_ERR "adutux: %s - error, can't find device for "
287 		       "minor %d\n", __func__, subminor);
288 		retval = -ENODEV;
289 		goto exit_no_device;
290 	}
291 
292 	dev = usb_get_intfdata(interface);
293 	if (!dev || !dev->udev) {
294 		retval = -ENODEV;
295 		goto exit_no_device;
296 	}
297 
298 	/* check that nobody else is using the device */
299 	if (dev->open_count) {
300 		retval = -EBUSY;
301 		goto exit_no_device;
302 	}
303 
304 	++dev->open_count;
305 	dbg(2,"%s : open count %d", __func__, dev->open_count);
306 
307 	/* save device in the file's private structure */
308 	file->private_data = dev;
309 
310 	/* initialize in direction */
311 	dev->read_buffer_length = 0;
312 
313 	/* fixup first read by having urb waiting for it */
314 	usb_fill_int_urb(dev->interrupt_in_urb,dev->udev,
315 			 usb_rcvintpipe(dev->udev,
316 					dev->interrupt_in_endpoint->bEndpointAddress),
317 			 dev->interrupt_in_buffer,
318 			 le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize),
319 			 adu_interrupt_in_callback, dev,
320 			 dev->interrupt_in_endpoint->bInterval);
321 	dev->read_urb_finished = 0;
322 	if (usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL))
323 		dev->read_urb_finished = 1;
324 	/* we ignore failure */
325 	/* end of fixup for first read */
326 
327 	/* initialize out direction */
328 	dev->out_urb_finished = 1;
329 
330 	retval = 0;
331 
332 exit_no_device:
333 	mutex_unlock(&adutux_mutex);
334 exit_no_lock:
335 	dbg(2,"%s : leave, return value %d ", __func__, retval);
336 	return retval;
337 }
338 
339 static void adu_release_internal(struct adu_device *dev)
340 {
341 	dbg(2," %s : enter", __func__);
342 
343 	/* decrement our usage count for the device */
344 	--dev->open_count;
345 	dbg(2," %s : open count %d", __func__, dev->open_count);
346 	if (dev->open_count <= 0) {
347 		adu_abort_transfers(dev);
348 		dev->open_count = 0;
349 	}
350 
351 	dbg(2," %s : leave", __func__);
352 }
353 
354 static int adu_release(struct inode *inode, struct file *file)
355 {
356 	struct adu_device *dev;
357 	int retval = 0;
358 
359 	dbg(2," %s : enter", __func__);
360 
361 	if (file == NULL) {
362  		dbg(1," %s : file is NULL", __func__);
363 		retval = -ENODEV;
364 		goto exit;
365 	}
366 
367 	dev = file->private_data;
368 	if (dev == NULL) {
369  		dbg(1," %s : object is NULL", __func__);
370 		retval = -ENODEV;
371 		goto exit;
372 	}
373 
374 	mutex_lock(&adutux_mutex); /* not interruptible */
375 
376 	if (dev->open_count <= 0) {
377 		dbg(1," %s : device not opened", __func__);
378 		retval = -ENODEV;
379 		goto unlock;
380 	}
381 
382 	adu_release_internal(dev);
383 	if (dev->udev == NULL) {
384 		/* the device was unplugged before the file was released */
385 		if (!dev->open_count)	/* ... and we're the last user */
386 			adu_delete(dev);
387 	}
388 unlock:
389 	mutex_unlock(&adutux_mutex);
390 exit:
391 	dbg(2," %s : leave, return value %d", __func__, retval);
392 	return retval;
393 }
394 
395 static ssize_t adu_read(struct file *file, __user char *buffer, size_t count,
396 			loff_t *ppos)
397 {
398 	struct adu_device *dev;
399 	size_t bytes_read = 0;
400 	size_t bytes_to_read = count;
401 	int i;
402 	int retval = 0;
403 	int timeout = 0;
404 	int should_submit = 0;
405 	unsigned long flags;
406 	DECLARE_WAITQUEUE(wait, current);
407 
408 	dbg(2," %s : enter, count = %Zd, file=%p", __func__, count, file);
409 
410 	dev = file->private_data;
411 	dbg(2," %s : dev=%p", __func__, dev);
412 
413 	if (mutex_lock_interruptible(&dev->mtx))
414 		return -ERESTARTSYS;
415 
416 	/* verify that the device wasn't unplugged */
417 	if (dev->udev == NULL) {
418 		retval = -ENODEV;
419 		printk(KERN_ERR "adutux: No device or device unplugged %d\n",
420 		       retval);
421 		goto exit;
422 	}
423 
424 	/* verify that some data was requested */
425 	if (count == 0) {
426 		dbg(1," %s : read request of 0 bytes", __func__);
427 		goto exit;
428 	}
429 
430 	timeout = COMMAND_TIMEOUT;
431 	dbg(2," %s : about to start looping", __func__);
432 	while (bytes_to_read) {
433 		int data_in_secondary = dev->secondary_tail - dev->secondary_head;
434 		dbg(2," %s : while, data_in_secondary=%d, status=%d",
435 		    __func__, data_in_secondary,
436 		    dev->interrupt_in_urb->status);
437 
438 		if (data_in_secondary) {
439 			/* drain secondary buffer */
440 			int amount = bytes_to_read < data_in_secondary ? bytes_to_read : data_in_secondary;
441 			i = copy_to_user(buffer, dev->read_buffer_secondary+dev->secondary_head, amount);
442 			if (i) {
443 				retval = -EFAULT;
444 				goto exit;
445 			}
446 			dev->secondary_head += (amount - i);
447 			bytes_read += (amount - i);
448 			bytes_to_read -= (amount - i);
449 			if (i) {
450 				retval = bytes_read ? bytes_read : -EFAULT;
451 				goto exit;
452 			}
453 		} else {
454 			/* we check the primary buffer */
455 			spin_lock_irqsave (&dev->buflock, flags);
456 			if (dev->read_buffer_length) {
457 				/* we secure access to the primary */
458 				char *tmp;
459 				dbg(2," %s : swap, read_buffer_length = %d",
460 				    __func__, dev->read_buffer_length);
461 				tmp = dev->read_buffer_secondary;
462 				dev->read_buffer_secondary = dev->read_buffer_primary;
463 				dev->read_buffer_primary = tmp;
464 				dev->secondary_head = 0;
465 				dev->secondary_tail = dev->read_buffer_length;
466 				dev->read_buffer_length = 0;
467 				spin_unlock_irqrestore(&dev->buflock, flags);
468 				/* we have a free buffer so use it */
469 				should_submit = 1;
470 			} else {
471 				/* even the primary was empty - we may need to do IO */
472 				if (!dev->read_urb_finished) {
473 					/* somebody is doing IO */
474 					spin_unlock_irqrestore(&dev->buflock, flags);
475 					dbg(2," %s : submitted already", __func__);
476 				} else {
477 					/* we must initiate input */
478 					dbg(2," %s : initiate input", __func__);
479 					dev->read_urb_finished = 0;
480 					spin_unlock_irqrestore(&dev->buflock, flags);
481 
482 					usb_fill_int_urb(dev->interrupt_in_urb,dev->udev,
483 							 usb_rcvintpipe(dev->udev,
484 							 		dev->interrupt_in_endpoint->bEndpointAddress),
485 							 dev->interrupt_in_buffer,
486 							 le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize),
487 							 adu_interrupt_in_callback,
488 							 dev,
489 							 dev->interrupt_in_endpoint->bInterval);
490 					retval = usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
491 					if (retval) {
492 						dev->read_urb_finished = 1;
493 						if (retval == -ENOMEM) {
494 							retval = bytes_read ? bytes_read : -ENOMEM;
495 						}
496 						dbg(2," %s : submit failed", __func__);
497 						goto exit;
498 					}
499 				}
500 
501 				/* we wait for I/O to complete */
502 				set_current_state(TASK_INTERRUPTIBLE);
503 				add_wait_queue(&dev->read_wait, &wait);
504 				spin_lock_irqsave(&dev->buflock, flags);
505 				if (!dev->read_urb_finished) {
506 					spin_unlock_irqrestore(&dev->buflock, flags);
507 					timeout = schedule_timeout(COMMAND_TIMEOUT);
508 				} else {
509 					spin_unlock_irqrestore(&dev->buflock, flags);
510 					set_current_state(TASK_RUNNING);
511 				}
512 				remove_wait_queue(&dev->read_wait, &wait);
513 
514 				if (timeout <= 0) {
515 					dbg(2," %s : timeout", __func__);
516 					retval = bytes_read ? bytes_read : -ETIMEDOUT;
517 					goto exit;
518 				}
519 
520 				if (signal_pending(current)) {
521 					dbg(2," %s : signal pending", __func__);
522 					retval = bytes_read ? bytes_read : -EINTR;
523 					goto exit;
524 				}
525 			}
526 		}
527 	}
528 
529 	retval = bytes_read;
530 	/* if the primary buffer is empty then use it */
531 	spin_lock_irqsave(&dev->buflock, flags);
532 	if (should_submit && dev->read_urb_finished) {
533 		dev->read_urb_finished = 0;
534 		spin_unlock_irqrestore(&dev->buflock, flags);
535 		usb_fill_int_urb(dev->interrupt_in_urb,dev->udev,
536 				 usb_rcvintpipe(dev->udev,
537 				 		dev->interrupt_in_endpoint->bEndpointAddress),
538 				dev->interrupt_in_buffer,
539 				le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize),
540 				adu_interrupt_in_callback,
541 				dev,
542 				dev->interrupt_in_endpoint->bInterval);
543 		if (usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL) != 0)
544 			dev->read_urb_finished = 1;
545 		/* we ignore failure */
546 	} else {
547 		spin_unlock_irqrestore(&dev->buflock, flags);
548 	}
549 
550 exit:
551 	/* unlock the device */
552 	mutex_unlock(&dev->mtx);
553 
554 	dbg(2," %s : leave, return value %d", __func__, retval);
555 	return retval;
556 }
557 
558 static ssize_t adu_write(struct file *file, const __user char *buffer,
559 			 size_t count, loff_t *ppos)
560 {
561 	DECLARE_WAITQUEUE(waita, current);
562 	struct adu_device *dev;
563 	size_t bytes_written = 0;
564 	size_t bytes_to_write;
565 	size_t buffer_size;
566 	unsigned long flags;
567 	int retval;
568 
569 	dbg(2," %s : enter, count = %Zd", __func__, count);
570 
571 	dev = file->private_data;
572 
573 	retval = mutex_lock_interruptible(&dev->mtx);
574 	if (retval)
575 		goto exit_nolock;
576 
577 	/* verify that the device wasn't unplugged */
578 	if (dev->udev == NULL) {
579 		retval = -ENODEV;
580 		printk(KERN_ERR "adutux: No device or device unplugged %d\n",
581 		       retval);
582 		goto exit;
583 	}
584 
585 	/* verify that we actually have some data to write */
586 	if (count == 0) {
587 		dbg(1," %s : write request of 0 bytes", __func__);
588 		goto exit;
589 	}
590 
591 	while (count > 0) {
592 		add_wait_queue(&dev->write_wait, &waita);
593 		set_current_state(TASK_INTERRUPTIBLE);
594 		spin_lock_irqsave(&dev->buflock, flags);
595 		if (!dev->out_urb_finished) {
596 			spin_unlock_irqrestore(&dev->buflock, flags);
597 
598 			mutex_unlock(&dev->mtx);
599 			if (signal_pending(current)) {
600 				dbg(1," %s : interrupted", __func__);
601 				set_current_state(TASK_RUNNING);
602 				retval = -EINTR;
603 				goto exit_onqueue;
604 			}
605 			if (schedule_timeout(COMMAND_TIMEOUT) == 0) {
606 				dbg(1, "%s - command timed out.", __func__);
607 				retval = -ETIMEDOUT;
608 				goto exit_onqueue;
609 			}
610 			remove_wait_queue(&dev->write_wait, &waita);
611 			retval = mutex_lock_interruptible(&dev->mtx);
612 			if (retval) {
613 				retval = bytes_written ? bytes_written : retval;
614 				goto exit_nolock;
615 			}
616 
617 			dbg(4," %s : in progress, count = %Zd", __func__, count);
618 		} else {
619 			spin_unlock_irqrestore(&dev->buflock, flags);
620 			set_current_state(TASK_RUNNING);
621 			remove_wait_queue(&dev->write_wait, &waita);
622 			dbg(4," %s : sending, count = %Zd", __func__, count);
623 
624 			/* write the data into interrupt_out_buffer from userspace */
625 			buffer_size = le16_to_cpu(dev->interrupt_out_endpoint->wMaxPacketSize);
626 			bytes_to_write = count > buffer_size ? buffer_size : count;
627 			dbg(4," %s : buffer_size = %Zd, count = %Zd, bytes_to_write = %Zd",
628 			    __func__, buffer_size, count, bytes_to_write);
629 
630 			if (copy_from_user(dev->interrupt_out_buffer, buffer, bytes_to_write) != 0) {
631 				retval = -EFAULT;
632 				goto exit;
633 			}
634 
635 			/* send off the urb */
636 			usb_fill_int_urb(
637 				dev->interrupt_out_urb,
638 				dev->udev,
639 				usb_sndintpipe(dev->udev, dev->interrupt_out_endpoint->bEndpointAddress),
640 				dev->interrupt_out_buffer,
641 				bytes_to_write,
642 				adu_interrupt_out_callback,
643 				dev,
644 				dev->interrupt_out_endpoint->bInterval);
645 			dev->interrupt_out_urb->actual_length = bytes_to_write;
646 			dev->out_urb_finished = 0;
647 			retval = usb_submit_urb(dev->interrupt_out_urb, GFP_KERNEL);
648 			if (retval < 0) {
649 				dev->out_urb_finished = 1;
650 				dev_err(&dev->udev->dev, "Couldn't submit "
651 					"interrupt_out_urb %d\n", retval);
652 				goto exit;
653 			}
654 
655 			buffer += bytes_to_write;
656 			count -= bytes_to_write;
657 
658 			bytes_written += bytes_to_write;
659 		}
660 	}
661 	mutex_unlock(&dev->mtx);
662 	return bytes_written;
663 
664 exit:
665 	mutex_unlock(&dev->mtx);
666 exit_nolock:
667 	dbg(2," %s : leave, return value %d", __func__, retval);
668 	return retval;
669 
670 exit_onqueue:
671 	remove_wait_queue(&dev->write_wait, &waita);
672 	return retval;
673 }
674 
675 /* file operations needed when we register this driver */
676 static const struct file_operations adu_fops = {
677 	.owner = THIS_MODULE,
678 	.read  = adu_read,
679 	.write = adu_write,
680 	.open = adu_open,
681 	.release = adu_release,
682 	.llseek = noop_llseek,
683 };
684 
685 /*
686  * usb class driver info in order to get a minor number from the usb core,
687  * and to have the device registered with devfs and the driver core
688  */
689 static struct usb_class_driver adu_class = {
690 	.name = "usb/adutux%d",
691 	.fops = &adu_fops,
692 	.minor_base = ADU_MINOR_BASE,
693 };
694 
695 /**
696  * adu_probe
697  *
698  * Called by the usb core when a new device is connected that it thinks
699  * this driver might be interested in.
700  */
701 static int adu_probe(struct usb_interface *interface,
702 		     const struct usb_device_id *id)
703 {
704 	struct usb_device *udev = interface_to_usbdev(interface);
705 	struct adu_device *dev = NULL;
706 	struct usb_host_interface *iface_desc;
707 	struct usb_endpoint_descriptor *endpoint;
708 	int retval = -ENODEV;
709 	int in_end_size;
710 	int out_end_size;
711 	int i;
712 
713 	dbg(2," %s : enter", __func__);
714 
715 	if (udev == NULL) {
716 		dev_err(&interface->dev, "udev is NULL.\n");
717 		goto exit;
718 	}
719 
720 	/* allocate memory for our device state and initialize it */
721 	dev = kzalloc(sizeof(struct adu_device), GFP_KERNEL);
722 	if (dev == NULL) {
723 		dev_err(&interface->dev, "Out of memory\n");
724 		retval = -ENOMEM;
725 		goto exit;
726 	}
727 
728 	mutex_init(&dev->mtx);
729 	spin_lock_init(&dev->buflock);
730 	dev->udev = udev;
731 	init_waitqueue_head(&dev->read_wait);
732 	init_waitqueue_head(&dev->write_wait);
733 
734 	iface_desc = &interface->altsetting[0];
735 
736 	/* set up the endpoint information */
737 	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
738 		endpoint = &iface_desc->endpoint[i].desc;
739 
740 		if (usb_endpoint_is_int_in(endpoint))
741 			dev->interrupt_in_endpoint = endpoint;
742 
743 		if (usb_endpoint_is_int_out(endpoint))
744 			dev->interrupt_out_endpoint = endpoint;
745 	}
746 	if (dev->interrupt_in_endpoint == NULL) {
747 		dev_err(&interface->dev, "interrupt in endpoint not found\n");
748 		goto error;
749 	}
750 	if (dev->interrupt_out_endpoint == NULL) {
751 		dev_err(&interface->dev, "interrupt out endpoint not found\n");
752 		goto error;
753 	}
754 
755 	in_end_size = le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize);
756 	out_end_size = le16_to_cpu(dev->interrupt_out_endpoint->wMaxPacketSize);
757 
758 	dev->read_buffer_primary = kmalloc((4 * in_end_size), GFP_KERNEL);
759 	if (!dev->read_buffer_primary) {
760 		dev_err(&interface->dev, "Couldn't allocate read_buffer_primary\n");
761 		retval = -ENOMEM;
762 		goto error;
763 	}
764 
765 	/* debug code prime the buffer */
766 	memset(dev->read_buffer_primary, 'a', in_end_size);
767 	memset(dev->read_buffer_primary + in_end_size, 'b', in_end_size);
768 	memset(dev->read_buffer_primary + (2 * in_end_size), 'c', in_end_size);
769 	memset(dev->read_buffer_primary + (3 * in_end_size), 'd', in_end_size);
770 
771 	dev->read_buffer_secondary = kmalloc((4 * in_end_size), GFP_KERNEL);
772 	if (!dev->read_buffer_secondary) {
773 		dev_err(&interface->dev, "Couldn't allocate read_buffer_secondary\n");
774 		retval = -ENOMEM;
775 		goto error;
776 	}
777 
778 	/* debug code prime the buffer */
779 	memset(dev->read_buffer_secondary, 'e', in_end_size);
780 	memset(dev->read_buffer_secondary + in_end_size, 'f', in_end_size);
781 	memset(dev->read_buffer_secondary + (2 * in_end_size), 'g', in_end_size);
782 	memset(dev->read_buffer_secondary + (3 * in_end_size), 'h', in_end_size);
783 
784 	dev->interrupt_in_buffer = kmalloc(in_end_size, GFP_KERNEL);
785 	if (!dev->interrupt_in_buffer) {
786 		dev_err(&interface->dev, "Couldn't allocate interrupt_in_buffer\n");
787 		goto error;
788 	}
789 
790 	/* debug code prime the buffer */
791 	memset(dev->interrupt_in_buffer, 'i', in_end_size);
792 
793 	dev->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
794 	if (!dev->interrupt_in_urb) {
795 		dev_err(&interface->dev, "Couldn't allocate interrupt_in_urb\n");
796 		goto error;
797 	}
798 	dev->interrupt_out_buffer = kmalloc(out_end_size, GFP_KERNEL);
799 	if (!dev->interrupt_out_buffer) {
800 		dev_err(&interface->dev, "Couldn't allocate interrupt_out_buffer\n");
801 		goto error;
802 	}
803 	dev->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
804 	if (!dev->interrupt_out_urb) {
805 		dev_err(&interface->dev, "Couldn't allocate interrupt_out_urb\n");
806 		goto error;
807 	}
808 
809 	if (!usb_string(udev, udev->descriptor.iSerialNumber, dev->serial_number,
810 			sizeof(dev->serial_number))) {
811 		dev_err(&interface->dev, "Could not retrieve serial number\n");
812 		goto error;
813 	}
814 	dbg(2," %s : serial_number=%s", __func__, dev->serial_number);
815 
816 	/* we can register the device now, as it is ready */
817 	usb_set_intfdata(interface, dev);
818 
819 	retval = usb_register_dev(interface, &adu_class);
820 
821 	if (retval) {
822 		/* something prevented us from registering this driver */
823 		dev_err(&interface->dev, "Not able to get a minor for this device.\n");
824 		usb_set_intfdata(interface, NULL);
825 		goto error;
826 	}
827 
828 	dev->minor = interface->minor;
829 
830 	/* let the user know what node this device is now attached to */
831 	dev_info(&interface->dev, "ADU%d %s now attached to /dev/usb/adutux%d\n",
832 		 udev->descriptor.idProduct, dev->serial_number,
833 		 (dev->minor - ADU_MINOR_BASE));
834 exit:
835 	dbg(2," %s : leave, return value %p (dev)", __func__, dev);
836 
837 	return retval;
838 
839 error:
840 	adu_delete(dev);
841 	return retval;
842 }
843 
844 /**
845  * adu_disconnect
846  *
847  * Called by the usb core when the device is removed from the system.
848  */
849 static void adu_disconnect(struct usb_interface *interface)
850 {
851 	struct adu_device *dev;
852 	int minor;
853 
854 	dbg(2," %s : enter", __func__);
855 
856 	dev = usb_get_intfdata(interface);
857 
858 	mutex_lock(&dev->mtx);	/* not interruptible */
859 	dev->udev = NULL;	/* poison */
860 	minor = dev->minor;
861 	usb_deregister_dev(interface, &adu_class);
862 	mutex_unlock(&dev->mtx);
863 
864 	mutex_lock(&adutux_mutex);
865 	usb_set_intfdata(interface, NULL);
866 
867 	/* if the device is not opened, then we clean up right now */
868 	dbg(2," %s : open count %d", __func__, dev->open_count);
869 	if (!dev->open_count)
870 		adu_delete(dev);
871 
872 	mutex_unlock(&adutux_mutex);
873 
874 	dev_info(&interface->dev, "ADU device adutux%d now disconnected\n",
875 		 (minor - ADU_MINOR_BASE));
876 
877 	dbg(2," %s : leave", __func__);
878 }
879 
880 /* usb specific object needed to register this driver with the usb subsystem */
881 static struct usb_driver adu_driver = {
882 	.name = "adutux",
883 	.probe = adu_probe,
884 	.disconnect = adu_disconnect,
885 	.id_table = device_table,
886 };
887 
888 static int __init adu_init(void)
889 {
890 	int result;
891 
892 	dbg(2," %s : enter", __func__);
893 
894 	/* register this driver with the USB subsystem */
895 	result = usb_register(&adu_driver);
896 	if (result < 0) {
897 		printk(KERN_ERR "usb_register failed for the "__FILE__
898 		       " driver. Error number %d\n", result);
899 		goto exit;
900 	}
901 
902 	printk(KERN_INFO "adutux " DRIVER_DESC " " DRIVER_VERSION "\n");
903 	printk(KERN_INFO "adutux is an experimental driver. "
904 	       "Use at your own risk\n");
905 
906 exit:
907 	dbg(2," %s : leave, return value %d", __func__, result);
908 
909 	return result;
910 }
911 
912 static void __exit adu_exit(void)
913 {
914 	dbg(2," %s : enter", __func__);
915 	/* deregister this driver with the USB subsystem */
916 	usb_deregister(&adu_driver);
917 	dbg(2," %s : leave", __func__);
918 }
919 
920 module_init(adu_init);
921 module_exit(adu_exit);
922 
923 MODULE_AUTHOR(DRIVER_AUTHOR);
924 MODULE_DESCRIPTION(DRIVER_DESC);
925 MODULE_LICENSE("GPL");
926