xref: /openbmc/linux/drivers/usb/misc/adutux.c (revision f42b3800)
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 __FILE__ " : " format " \n", ## 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 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 __FILE__": %s - length = %d, data = ",
136 	       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", __FUNCTION__);
151 
152 	if (dev->udev == NULL) {
153 		dbg(1," %s : udev is null", __FUNCTION__);
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", __FUNCTION__);
176 }
177 
178 static void adu_delete(struct adu_device *dev)
179 {
180 	dbg(2, "%s enter", __FUNCTION__);
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", __FUNCTION__);
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", __FUNCTION__, status);
200 	adu_debug_data(5, __FUNCTION__, 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 			    __FUNCTION__, 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 ", __FUNCTION__,
224 			    urb->actual_length);
225 		} else {
226 			dbg(1," %s : read_buffer overflow", __FUNCTION__);
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, __FUNCTION__, urb->actual_length,
236 		       urb->transfer_buffer);
237 	dbg(4," %s : leave, status %d", __FUNCTION__, 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", __FUNCTION__, status);
246 	adu_debug_data(5,__FUNCTION__, 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 			    __FUNCTION__, 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, __FUNCTION__, urb->actual_length,
264 		       urb->transfer_buffer);
265 	dbg(4," %s : leave, status %d", __FUNCTION__, 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", __FUNCTION__);
276 
277 	subminor = iminor(inode);
278 
279 	if ((retval = mutex_lock_interruptible(&adutux_mutex))) {
280 		dbg(2, "%s : mutex lock failed", __FUNCTION__);
281 		goto exit_no_lock;
282 	}
283 
284 	interface = usb_find_interface(&adu_driver, subminor);
285 	if (!interface) {
286 		err("%s - error, can't find device for minor %d",
287 		    __FUNCTION__, 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", __FUNCTION__, 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 ", __FUNCTION__, retval);
336 	return retval;
337 }
338 
339 static void adu_release_internal(struct adu_device *dev)
340 {
341 	dbg(2," %s : enter", __FUNCTION__);
342 
343 	/* decrement our usage count for the device */
344 	--dev->open_count;
345 	dbg(2," %s : open count %d", __FUNCTION__, 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", __FUNCTION__);
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", __FUNCTION__);
360 
361 	if (file == NULL) {
362  		dbg(1," %s : file is NULL", __FUNCTION__);
363 		retval = -ENODEV;
364 		goto exit;
365 	}
366 
367 	dev = file->private_data;
368 	if (dev == NULL) {
369  		dbg(1," %s : object is NULL", __FUNCTION__);
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", __FUNCTION__);
378 		retval = -ENODEV;
379 		goto exit;
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 
389 exit:
390 	mutex_unlock(&adutux_mutex);
391 	dbg(2," %s : leave, return value %d", __FUNCTION__, 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", __FUNCTION__, count, file);
409 
410 	dev = file->private_data;
411 	dbg(2," %s : dev=%p", __FUNCTION__, 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 		err("No device or device unplugged %d", retval);
420 		goto exit;
421 	}
422 
423 	/* verify that some data was requested */
424 	if (count == 0) {
425 		dbg(1," %s : read request of 0 bytes", __FUNCTION__);
426 		goto exit;
427 	}
428 
429 	timeout = COMMAND_TIMEOUT;
430 	dbg(2," %s : about to start looping", __FUNCTION__);
431 	while (bytes_to_read) {
432 		int data_in_secondary = dev->secondary_tail - dev->secondary_head;
433 		dbg(2," %s : while, data_in_secondary=%d, status=%d",
434 		    __FUNCTION__, data_in_secondary,
435 		    dev->interrupt_in_urb->status);
436 
437 		if (data_in_secondary) {
438 			/* drain secondary buffer */
439 			int amount = bytes_to_read < data_in_secondary ? bytes_to_read : data_in_secondary;
440 			i = copy_to_user(buffer, dev->read_buffer_secondary+dev->secondary_head, amount);
441 			if (i < 0) {
442 				retval = -EFAULT;
443 				goto exit;
444 			}
445 			dev->secondary_head += (amount - i);
446 			bytes_read += (amount - i);
447 			bytes_to_read -= (amount - i);
448 			if (i) {
449 				retval = bytes_read ? bytes_read : -EFAULT;
450 				goto exit;
451 			}
452 		} else {
453 			/* we check the primary buffer */
454 			spin_lock_irqsave (&dev->buflock, flags);
455 			if (dev->read_buffer_length) {
456 				/* we secure access to the primary */
457 				char *tmp;
458 				dbg(2," %s : swap, read_buffer_length = %d",
459 				    __FUNCTION__, dev->read_buffer_length);
460 				tmp = dev->read_buffer_secondary;
461 				dev->read_buffer_secondary = dev->read_buffer_primary;
462 				dev->read_buffer_primary = tmp;
463 				dev->secondary_head = 0;
464 				dev->secondary_tail = dev->read_buffer_length;
465 				dev->read_buffer_length = 0;
466 				spin_unlock_irqrestore(&dev->buflock, flags);
467 				/* we have a free buffer so use it */
468 				should_submit = 1;
469 			} else {
470 				/* even the primary was empty - we may need to do IO */
471 				if (!dev->read_urb_finished) {
472 					/* somebody is doing IO */
473 					spin_unlock_irqrestore(&dev->buflock, flags);
474 					dbg(2," %s : submitted already", __FUNCTION__);
475 				} else {
476 					/* we must initiate input */
477 					dbg(2," %s : initiate input", __FUNCTION__);
478 					dev->read_urb_finished = 0;
479 					spin_unlock_irqrestore(&dev->buflock, flags);
480 
481 					usb_fill_int_urb(dev->interrupt_in_urb,dev->udev,
482 							 usb_rcvintpipe(dev->udev,
483 							 		dev->interrupt_in_endpoint->bEndpointAddress),
484 							 dev->interrupt_in_buffer,
485 							 le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize),
486 							 adu_interrupt_in_callback,
487 							 dev,
488 							 dev->interrupt_in_endpoint->bInterval);
489 					retval = usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
490 					if (retval) {
491 						dev->read_urb_finished = 1;
492 						if (retval == -ENOMEM) {
493 							retval = bytes_read ? bytes_read : -ENOMEM;
494 						}
495 						dbg(2," %s : submit failed", __FUNCTION__);
496 						goto exit;
497 					}
498 				}
499 
500 				/* we wait for I/O to complete */
501 				set_current_state(TASK_INTERRUPTIBLE);
502 				add_wait_queue(&dev->read_wait, &wait);
503 				spin_lock_irqsave(&dev->buflock, flags);
504 				if (!dev->read_urb_finished) {
505 					spin_unlock_irqrestore(&dev->buflock, flags);
506 					timeout = schedule_timeout(COMMAND_TIMEOUT);
507 				} else {
508 					spin_unlock_irqrestore(&dev->buflock, flags);
509 					set_current_state(TASK_RUNNING);
510 				}
511 				remove_wait_queue(&dev->read_wait, &wait);
512 
513 				if (timeout <= 0) {
514 					dbg(2," %s : timeout", __FUNCTION__);
515 					retval = bytes_read ? bytes_read : -ETIMEDOUT;
516 					goto exit;
517 				}
518 
519 				if (signal_pending(current)) {
520 					dbg(2," %s : signal pending", __FUNCTION__);
521 					retval = bytes_read ? bytes_read : -EINTR;
522 					goto exit;
523 				}
524 			}
525 		}
526 	}
527 
528 	retval = bytes_read;
529 	/* if the primary buffer is empty then use it */
530 	spin_lock_irqsave(&dev->buflock, flags);
531 	if (should_submit && dev->read_urb_finished) {
532 		dev->read_urb_finished = 0;
533 		spin_unlock_irqrestore(&dev->buflock, flags);
534 		usb_fill_int_urb(dev->interrupt_in_urb,dev->udev,
535 				 usb_rcvintpipe(dev->udev,
536 				 		dev->interrupt_in_endpoint->bEndpointAddress),
537 				dev->interrupt_in_buffer,
538 				le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize),
539 				adu_interrupt_in_callback,
540 				dev,
541 				dev->interrupt_in_endpoint->bInterval);
542 		if (usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL) != 0)
543 			dev->read_urb_finished = 1;
544 		/* we ignore failure */
545 	} else {
546 		spin_unlock_irqrestore(&dev->buflock, flags);
547 	}
548 
549 exit:
550 	/* unlock the device */
551 	mutex_unlock(&dev->mtx);
552 
553 	dbg(2," %s : leave, return value %d", __FUNCTION__, retval);
554 	return retval;
555 }
556 
557 static ssize_t adu_write(struct file *file, const __user char *buffer,
558 			 size_t count, loff_t *ppos)
559 {
560 	DECLARE_WAITQUEUE(waita, current);
561 	struct adu_device *dev;
562 	size_t bytes_written = 0;
563 	size_t bytes_to_write;
564 	size_t buffer_size;
565 	unsigned long flags;
566 	int retval;
567 
568 	dbg(2," %s : enter, count = %Zd", __FUNCTION__, count);
569 
570 	dev = file->private_data;
571 
572 	retval = mutex_lock_interruptible(&dev->mtx);
573 	if (retval)
574 		goto exit_nolock;
575 
576 	/* verify that the device wasn't unplugged */
577 	if (dev->udev == NULL) {
578 		retval = -ENODEV;
579 		err("No device or device unplugged %d", retval);
580 		goto exit;
581 	}
582 
583 	/* verify that we actually have some data to write */
584 	if (count == 0) {
585 		dbg(1," %s : write request of 0 bytes", __FUNCTION__);
586 		goto exit;
587 	}
588 
589 	while (count > 0) {
590 		add_wait_queue(&dev->write_wait, &waita);
591 		set_current_state(TASK_INTERRUPTIBLE);
592 		spin_lock_irqsave(&dev->buflock, flags);
593 		if (!dev->out_urb_finished) {
594 			spin_unlock_irqrestore(&dev->buflock, flags);
595 
596 			mutex_unlock(&dev->mtx);
597 			if (signal_pending(current)) {
598 				dbg(1," %s : interrupted", __FUNCTION__);
599 				set_current_state(TASK_RUNNING);
600 				retval = -EINTR;
601 				goto exit_onqueue;
602 			}
603 			if (schedule_timeout(COMMAND_TIMEOUT) == 0) {
604 				dbg(1, "%s - command timed out.", __FUNCTION__);
605 				retval = -ETIMEDOUT;
606 				goto exit_onqueue;
607 			}
608 			remove_wait_queue(&dev->write_wait, &waita);
609 			retval = mutex_lock_interruptible(&dev->mtx);
610 			if (retval) {
611 				retval = bytes_written ? bytes_written : retval;
612 				goto exit_nolock;
613 			}
614 
615 			dbg(4," %s : in progress, count = %Zd", __FUNCTION__, count);
616 		} else {
617 			spin_unlock_irqrestore(&dev->buflock, flags);
618 			set_current_state(TASK_RUNNING);
619 			remove_wait_queue(&dev->write_wait, &waita);
620 			dbg(4," %s : sending, count = %Zd", __FUNCTION__, count);
621 
622 			/* write the data into interrupt_out_buffer from userspace */
623 			buffer_size = le16_to_cpu(dev->interrupt_out_endpoint->wMaxPacketSize);
624 			bytes_to_write = count > buffer_size ? buffer_size : count;
625 			dbg(4," %s : buffer_size = %Zd, count = %Zd, bytes_to_write = %Zd",
626 			    __FUNCTION__, buffer_size, count, bytes_to_write);
627 
628 			if (copy_from_user(dev->interrupt_out_buffer, buffer, bytes_to_write) != 0) {
629 				retval = -EFAULT;
630 				goto exit;
631 			}
632 
633 			/* send off the urb */
634 			usb_fill_int_urb(
635 				dev->interrupt_out_urb,
636 				dev->udev,
637 				usb_sndintpipe(dev->udev, dev->interrupt_out_endpoint->bEndpointAddress),
638 				dev->interrupt_out_buffer,
639 				bytes_to_write,
640 				adu_interrupt_out_callback,
641 				dev,
642 				dev->interrupt_out_endpoint->bInterval);
643 			dev->interrupt_out_urb->actual_length = bytes_to_write;
644 			dev->out_urb_finished = 0;
645 			retval = usb_submit_urb(dev->interrupt_out_urb, GFP_KERNEL);
646 			if (retval < 0) {
647 				dev->out_urb_finished = 1;
648 				err("Couldn't submit interrupt_out_urb %d", retval);
649 				goto exit;
650 			}
651 
652 			buffer += bytes_to_write;
653 			count -= bytes_to_write;
654 
655 			bytes_written += bytes_to_write;
656 		}
657 	}
658 	mutex_unlock(&dev->mtx);
659 	return bytes_written;
660 
661 exit:
662 	mutex_unlock(&dev->mtx);
663 exit_nolock:
664 	dbg(2," %s : leave, return value %d", __FUNCTION__, retval);
665 	return retval;
666 
667 exit_onqueue:
668 	remove_wait_queue(&dev->write_wait, &waita);
669 	return retval;
670 }
671 
672 /* file operations needed when we register this driver */
673 static const struct file_operations adu_fops = {
674 	.owner = THIS_MODULE,
675 	.read  = adu_read,
676 	.write = adu_write,
677 	.open = adu_open,
678 	.release = adu_release,
679 };
680 
681 /*
682  * usb class driver info in order to get a minor number from the usb core,
683  * and to have the device registered with devfs and the driver core
684  */
685 static struct usb_class_driver adu_class = {
686 	.name = "usb/adutux%d",
687 	.fops = &adu_fops,
688 	.minor_base = ADU_MINOR_BASE,
689 };
690 
691 /**
692  * adu_probe
693  *
694  * Called by the usb core when a new device is connected that it thinks
695  * this driver might be interested in.
696  */
697 static int adu_probe(struct usb_interface *interface,
698 		     const struct usb_device_id *id)
699 {
700 	struct usb_device *udev = interface_to_usbdev(interface);
701 	struct adu_device *dev = NULL;
702 	struct usb_host_interface *iface_desc;
703 	struct usb_endpoint_descriptor *endpoint;
704 	int retval = -ENODEV;
705 	int in_end_size;
706 	int out_end_size;
707 	int i;
708 
709 	dbg(2," %s : enter", __FUNCTION__);
710 
711 	if (udev == NULL) {
712 		dev_err(&interface->dev, "udev is NULL.\n");
713 		goto exit;
714 	}
715 
716 	/* allocate memory for our device state and intialize it */
717 	dev = kzalloc(sizeof(struct adu_device), GFP_KERNEL);
718 	if (dev == NULL) {
719 		dev_err(&interface->dev, "Out of memory\n");
720 		retval = -ENOMEM;
721 		goto exit;
722 	}
723 
724 	mutex_init(&dev->mtx);
725 	spin_lock_init(&dev->buflock);
726 	dev->udev = udev;
727 	init_waitqueue_head(&dev->read_wait);
728 	init_waitqueue_head(&dev->write_wait);
729 
730 	iface_desc = &interface->altsetting[0];
731 
732 	/* set up the endpoint information */
733 	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
734 		endpoint = &iface_desc->endpoint[i].desc;
735 
736 		if (usb_endpoint_is_int_in(endpoint))
737 			dev->interrupt_in_endpoint = endpoint;
738 
739 		if (usb_endpoint_is_int_out(endpoint))
740 			dev->interrupt_out_endpoint = endpoint;
741 	}
742 	if (dev->interrupt_in_endpoint == NULL) {
743 		dev_err(&interface->dev, "interrupt in endpoint not found\n");
744 		goto error;
745 	}
746 	if (dev->interrupt_out_endpoint == NULL) {
747 		dev_err(&interface->dev, "interrupt out endpoint not found\n");
748 		goto error;
749 	}
750 
751 	in_end_size = le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize);
752 	out_end_size = le16_to_cpu(dev->interrupt_out_endpoint->wMaxPacketSize);
753 
754 	dev->read_buffer_primary = kmalloc((4 * in_end_size), GFP_KERNEL);
755 	if (!dev->read_buffer_primary) {
756 		dev_err(&interface->dev, "Couldn't allocate read_buffer_primary\n");
757 		retval = -ENOMEM;
758 		goto error;
759 	}
760 
761 	/* debug code prime the buffer */
762 	memset(dev->read_buffer_primary, 'a', in_end_size);
763 	memset(dev->read_buffer_primary + in_end_size, 'b', in_end_size);
764 	memset(dev->read_buffer_primary + (2 * in_end_size), 'c', in_end_size);
765 	memset(dev->read_buffer_primary + (3 * in_end_size), 'd', in_end_size);
766 
767 	dev->read_buffer_secondary = kmalloc((4 * in_end_size), GFP_KERNEL);
768 	if (!dev->read_buffer_secondary) {
769 		dev_err(&interface->dev, "Couldn't allocate read_buffer_secondary\n");
770 		retval = -ENOMEM;
771 		goto error;
772 	}
773 
774 	/* debug code prime the buffer */
775 	memset(dev->read_buffer_secondary, 'e', in_end_size);
776 	memset(dev->read_buffer_secondary + in_end_size, 'f', in_end_size);
777 	memset(dev->read_buffer_secondary + (2 * in_end_size), 'g', in_end_size);
778 	memset(dev->read_buffer_secondary + (3 * in_end_size), 'h', in_end_size);
779 
780 	dev->interrupt_in_buffer = kmalloc(in_end_size, GFP_KERNEL);
781 	if (!dev->interrupt_in_buffer) {
782 		dev_err(&interface->dev, "Couldn't allocate interrupt_in_buffer\n");
783 		goto error;
784 	}
785 
786 	/* debug code prime the buffer */
787 	memset(dev->interrupt_in_buffer, 'i', in_end_size);
788 
789 	dev->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
790 	if (!dev->interrupt_in_urb) {
791 		dev_err(&interface->dev, "Couldn't allocate interrupt_in_urb\n");
792 		goto error;
793 	}
794 	dev->interrupt_out_buffer = kmalloc(out_end_size, GFP_KERNEL);
795 	if (!dev->interrupt_out_buffer) {
796 		dev_err(&interface->dev, "Couldn't allocate interrupt_out_buffer\n");
797 		goto error;
798 	}
799 	dev->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
800 	if (!dev->interrupt_out_urb) {
801 		dev_err(&interface->dev, "Couldn't allocate interrupt_out_urb\n");
802 		goto error;
803 	}
804 
805 	if (!usb_string(udev, udev->descriptor.iSerialNumber, dev->serial_number,
806 			sizeof(dev->serial_number))) {
807 		dev_err(&interface->dev, "Could not retrieve serial number\n");
808 		goto error;
809 	}
810 	dbg(2," %s : serial_number=%s", __FUNCTION__, dev->serial_number);
811 
812 	/* we can register the device now, as it is ready */
813 	usb_set_intfdata(interface, dev);
814 
815 	retval = usb_register_dev(interface, &adu_class);
816 
817 	if (retval) {
818 		/* something prevented us from registering this driver */
819 		dev_err(&interface->dev, "Not able to get a minor for this device.\n");
820 		usb_set_intfdata(interface, NULL);
821 		goto error;
822 	}
823 
824 	dev->minor = interface->minor;
825 
826 	/* let the user know what node this device is now attached to */
827 	dev_info(&interface->dev, "ADU%d %s now attached to /dev/usb/adutux%d\n",
828 		 udev->descriptor.idProduct, dev->serial_number,
829 		 (dev->minor - ADU_MINOR_BASE));
830 exit:
831 	dbg(2," %s : leave, return value %p (dev)", __FUNCTION__, dev);
832 
833 	return retval;
834 
835 error:
836 	adu_delete(dev);
837 	return retval;
838 }
839 
840 /**
841  * adu_disconnect
842  *
843  * Called by the usb core when the device is removed from the system.
844  */
845 static void adu_disconnect(struct usb_interface *interface)
846 {
847 	struct adu_device *dev;
848 	int minor;
849 
850 	dbg(2," %s : enter", __FUNCTION__);
851 
852 	dev = usb_get_intfdata(interface);
853 
854 	mutex_lock(&dev->mtx);	/* not interruptible */
855 	dev->udev = NULL;	/* poison */
856 	minor = dev->minor;
857 	usb_deregister_dev(interface, &adu_class);
858 	mutex_unlock(&dev->mtx);
859 
860 	mutex_lock(&adutux_mutex);
861 	usb_set_intfdata(interface, NULL);
862 
863 	/* if the device is not opened, then we clean up right now */
864 	dbg(2," %s : open count %d", __FUNCTION__, dev->open_count);
865 	if (!dev->open_count)
866 		adu_delete(dev);
867 
868 	mutex_unlock(&adutux_mutex);
869 
870 	dev_info(&interface->dev, "ADU device adutux%d now disconnected\n",
871 		 (minor - ADU_MINOR_BASE));
872 
873 	dbg(2," %s : leave", __FUNCTION__);
874 }
875 
876 /* usb specific object needed to register this driver with the usb subsystem */
877 static struct usb_driver adu_driver = {
878 	.name = "adutux",
879 	.probe = adu_probe,
880 	.disconnect = adu_disconnect,
881 	.id_table = device_table,
882 };
883 
884 static int __init adu_init(void)
885 {
886 	int result;
887 
888 	dbg(2," %s : enter", __FUNCTION__);
889 
890 	/* register this driver with the USB subsystem */
891 	result = usb_register(&adu_driver);
892 	if (result < 0) {
893 		err("usb_register failed for the "__FILE__" driver. "
894 		    "Error number %d", result);
895 		goto exit;
896 	}
897 
898 	info("adutux " DRIVER_DESC " " DRIVER_VERSION);
899 	info("adutux is an experimental driver. Use at your own risk");
900 
901 exit:
902 	dbg(2," %s : leave, return value %d", __FUNCTION__, result);
903 
904 	return result;
905 }
906 
907 static void __exit adu_exit(void)
908 {
909 	dbg(2," %s : enter", __FUNCTION__);
910 	/* deregister this driver with the USB subsystem */
911 	usb_deregister(&adu_driver);
912 	dbg(2," %s : leave", __FUNCTION__);
913 }
914 
915 module_init(adu_init);
916 module_exit(adu_exit);
917 
918 MODULE_AUTHOR(DRIVER_AUTHOR);
919 MODULE_DESCRIPTION(DRIVER_DESC);
920 MODULE_LICENSE("GPL");
921