xref: /linux/drivers/usb/misc/adutux.c (revision c537b994505099b7197e7d3125b942ecbcc51eb6)
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 <asm/uaccess.h>
28 
29 #ifdef CONFIG_USB_DEBUG
30 static int debug = 5;
31 #else
32 static int debug = 1;
33 #endif
34 
35 /* Use our own dbg macro */
36 #undef dbg
37 #define dbg(lvl, format, arg...) 					\
38 do { 									\
39 	if (debug >= lvl)						\
40 		printk(KERN_DEBUG __FILE__ " : " format " \n", ## arg);	\
41 } while (0)
42 
43 
44 /* Version Information */
45 #define DRIVER_VERSION "v0.0.13"
46 #define DRIVER_AUTHOR "John Homppi"
47 #define DRIVER_DESC "adutux (see www.ontrak.net)"
48 
49 /* Module parameters */
50 module_param(debug, int, S_IRUGO | S_IWUSR);
51 MODULE_PARM_DESC(debug, "Debug enabled or not");
52 
53 /* Define these values to match your device */
54 #define ADU_VENDOR_ID 0x0a07
55 #define ADU_PRODUCT_ID 0x0064
56 
57 /* table of devices that work with this driver */
58 static struct usb_device_id device_table [] = {
59 	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID) },		/* ADU100 */
60 	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID+20) }, 	/* ADU120 */
61 	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID+30) }, 	/* ADU130 */
62 	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID+100) },	/* ADU200 */
63 	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID+108) },	/* ADU208 */
64 	{ USB_DEVICE(ADU_VENDOR_ID, ADU_PRODUCT_ID+118) },	/* ADU218 */
65 	{ }/* Terminating entry */
66 };
67 
68 MODULE_DEVICE_TABLE(usb, device_table);
69 
70 #ifdef CONFIG_USB_DYNAMIC_MINORS
71 #define ADU_MINOR_BASE	0
72 #else
73 #define ADU_MINOR_BASE	67
74 #endif
75 
76 /* we can have up to this number of device plugged in at once */
77 #define MAX_DEVICES	16
78 
79 #define COMMAND_TIMEOUT	(2*HZ)	/* 60 second timeout for a command */
80 
81 /* Structure to hold all of our device specific stuff */
82 struct adu_device {
83 	struct semaphore	sem; /* locks this structure */
84 	struct usb_device*	udev; /* save off the usb device pointer */
85 	struct usb_interface*	interface;
86 	unsigned char		minor; /* the starting minor number for this device */
87 	char			serial_number[8];
88 
89 	int			open_count; /* number of times this port has been opened */
90 
91 	char*			read_buffer_primary;
92 	int			read_buffer_length;
93 	char*			read_buffer_secondary;
94 	int			secondary_head;
95 	int			secondary_tail;
96 	spinlock_t		buflock;
97 
98 	wait_queue_head_t	read_wait;
99 	wait_queue_head_t	write_wait;
100 
101 	char*			interrupt_in_buffer;
102 	struct usb_endpoint_descriptor* interrupt_in_endpoint;
103 	struct urb*		interrupt_in_urb;
104 	int			read_urb_finished;
105 
106 	char*			interrupt_out_buffer;
107 	struct usb_endpoint_descriptor* interrupt_out_endpoint;
108 	struct urb*		interrupt_out_urb;
109 };
110 
111 /* prevent races between open() and disconnect */
112 static DEFINE_MUTEX(disconnect_mutex);
113 static struct usb_driver adu_driver;
114 
115 static void adu_debug_data(int level, const char *function, int size,
116 			   const unsigned char *data)
117 {
118 	int i;
119 
120 	if (debug < level)
121 		return;
122 
123 	printk(KERN_DEBUG __FILE__": %s - length = %d, data = ",
124 	       function, size);
125 	for (i = 0; i < size; ++i)
126 		printk("%.2x ", data[i]);
127 	printk("\n");
128 }
129 
130 /**
131  * adu_abort_transfers
132  *      aborts transfers and frees associated data structures
133  */
134 static void adu_abort_transfers(struct adu_device *dev)
135 {
136 	dbg(2," %s : enter", __FUNCTION__);
137 
138 	if (dev == NULL) {
139 		dbg(1," %s : dev is null", __FUNCTION__);
140 		goto exit;
141 	}
142 
143 	if (dev->udev == NULL) {
144 		dbg(1," %s : udev is null", __FUNCTION__);
145 		goto exit;
146 	}
147 
148 	dbg(2," %s : udev state %d", __FUNCTION__, dev->udev->state);
149 	if (dev->udev->state == USB_STATE_NOTATTACHED) {
150 		dbg(1," %s : udev is not attached", __FUNCTION__);
151 		goto exit;
152 	}
153 
154 	/* shutdown transfer */
155 	usb_unlink_urb(dev->interrupt_in_urb);
156 	usb_unlink_urb(dev->interrupt_out_urb);
157 
158 exit:
159 	dbg(2," %s : leave", __FUNCTION__);
160 }
161 
162 static void adu_delete(struct adu_device *dev)
163 {
164 	dbg(2, "%s enter", __FUNCTION__);
165 
166 	adu_abort_transfers(dev);
167 
168 	/* free data structures */
169 	usb_free_urb(dev->interrupt_in_urb);
170 	usb_free_urb(dev->interrupt_out_urb);
171 	kfree(dev->read_buffer_primary);
172 	kfree(dev->read_buffer_secondary);
173 	kfree(dev->interrupt_in_buffer);
174 	kfree(dev->interrupt_out_buffer);
175 	kfree(dev);
176 
177 	dbg(2, "%s : leave", __FUNCTION__);
178 }
179 
180 static void adu_interrupt_in_callback(struct urb *urb)
181 {
182 	struct adu_device *dev = urb->context;
183 
184 	dbg(4," %s : enter, status %d", __FUNCTION__, urb->status);
185 	adu_debug_data(5, __FUNCTION__, urb->actual_length,
186 		       urb->transfer_buffer);
187 
188 	spin_lock(&dev->buflock);
189 
190 	if (urb->status != 0) {
191 		if ((urb->status != -ENOENT) && (urb->status != -ECONNRESET)) {
192 			dbg(1," %s : nonzero status received: %d",
193 			    __FUNCTION__, urb->status);
194 		}
195 		goto exit;
196 	}
197 
198 	if (urb->actual_length > 0 && dev->interrupt_in_buffer[0] != 0x00) {
199 		if (dev->read_buffer_length <
200 		    (4 * le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize)) -
201 		     (urb->actual_length)) {
202 			memcpy (dev->read_buffer_primary +
203 				dev->read_buffer_length,
204 				dev->interrupt_in_buffer, urb->actual_length);
205 
206 			dev->read_buffer_length += urb->actual_length;
207 			dbg(2," %s reading  %d ", __FUNCTION__,
208 			    urb->actual_length);
209 		} else {
210 			dbg(1," %s : read_buffer overflow", __FUNCTION__);
211 		}
212 	}
213 
214 exit:
215 	dev->read_urb_finished = 1;
216 	spin_unlock(&dev->buflock);
217 	/* always wake up so we recover from errors */
218 	wake_up_interruptible(&dev->read_wait);
219 	adu_debug_data(5, __FUNCTION__, urb->actual_length,
220 		       urb->transfer_buffer);
221 	dbg(4," %s : leave, status %d", __FUNCTION__, urb->status);
222 }
223 
224 static void adu_interrupt_out_callback(struct urb *urb)
225 {
226 	struct adu_device *dev = urb->context;
227 
228 	dbg(4," %s : enter, status %d", __FUNCTION__, urb->status);
229 	adu_debug_data(5,__FUNCTION__, urb->actual_length, urb->transfer_buffer);
230 
231 	if (urb->status != 0) {
232 		if ((urb->status != -ENOENT) &&
233 		    (urb->status != -ECONNRESET)) {
234 			dbg(1, " %s :nonzero status received: %d",
235 			    __FUNCTION__, urb->status);
236 		}
237 		goto exit;
238 	}
239 
240 	wake_up_interruptible(&dev->write_wait);
241 exit:
242 
243 	adu_debug_data(5, __FUNCTION__, urb->actual_length,
244 		       urb->transfer_buffer);
245 	dbg(4," %s : leave, status %d", __FUNCTION__, urb->status);
246 }
247 
248 static int adu_open(struct inode *inode, struct file *file)
249 {
250 	struct adu_device *dev = NULL;
251 	struct usb_interface *interface;
252 	int subminor;
253 	int retval = 0;
254 
255 	dbg(2,"%s : enter", __FUNCTION__);
256 
257 	subminor = iminor(inode);
258 
259 	mutex_lock(&disconnect_mutex);
260 
261 	interface = usb_find_interface(&adu_driver, subminor);
262 	if (!interface) {
263 		err("%s - error, can't find device for minor %d",
264 		    __FUNCTION__, subminor);
265 		retval = -ENODEV;
266 		goto exit_no_device;
267 	}
268 
269 	dev = usb_get_intfdata(interface);
270 	if (!dev) {
271 		retval = -ENODEV;
272 		goto exit_no_device;
273 	}
274 
275 	/* lock this device */
276 	if ((retval = down_interruptible(&dev->sem))) {
277 		dbg(2, "%s : sem down failed", __FUNCTION__);
278 		goto exit_no_device;
279 	}
280 
281 	/* increment our usage count for the device */
282 	++dev->open_count;
283 	dbg(2,"%s : open count %d", __FUNCTION__, dev->open_count);
284 
285 	/* save device in the file's private structure */
286 	file->private_data = dev;
287 
288 	/* initialize in direction */
289 	dev->read_buffer_length = 0;
290 
291 	/* fixup first read by having urb waiting for it */
292 	usb_fill_int_urb(dev->interrupt_in_urb,dev->udev,
293 			 usb_rcvintpipe(dev->udev,
294 			 		dev->interrupt_in_endpoint->bEndpointAddress),
295 			 dev->interrupt_in_buffer,
296 			 le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize),
297 			 adu_interrupt_in_callback, dev,
298 			 dev->interrupt_in_endpoint->bInterval);
299 	/* dev->interrupt_in_urb->transfer_flags |= URB_ASYNC_UNLINK; */
300 	dev->read_urb_finished = 0;
301 	usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
302 	/* we ignore failure */
303 	/* end of fixup for first read */
304 
305 	up(&dev->sem);
306 
307 exit_no_device:
308 	mutex_unlock(&disconnect_mutex);
309 	dbg(2,"%s : leave, return value %d ", __FUNCTION__, retval);
310 
311 	return retval;
312 }
313 
314 static int adu_release_internal(struct adu_device *dev)
315 {
316 	int retval = 0;
317 
318 	dbg(2," %s : enter", __FUNCTION__);
319 
320 	if (dev->udev == NULL) {
321 		/* the device was unplugged before the file was released */
322 		adu_delete(dev);
323 		goto exit;
324 	}
325 
326 	/* decrement our usage count for the device */
327 	--dev->open_count;
328 	dbg(2," %s : open count %d", __FUNCTION__, dev->open_count);
329 	if (dev->open_count <= 0) {
330 		adu_abort_transfers(dev);
331 		dev->open_count = 0;
332 	}
333 
334 exit:
335 	dbg(2," %s : leave", __FUNCTION__);
336 	return retval;
337 }
338 
339 static int adu_release(struct inode *inode, struct file *file)
340 {
341 	struct adu_device *dev = NULL;
342 	int retval = 0;
343 
344 	dbg(2," %s : enter", __FUNCTION__);
345 
346 	if (file == NULL) {
347  		dbg(1," %s : file is NULL", __FUNCTION__);
348 		retval = -ENODEV;
349 		goto exit;
350 	}
351 
352 	dev = file->private_data;
353 
354 	if (dev == NULL) {
355  		dbg(1," %s : object is NULL", __FUNCTION__);
356 		retval = -ENODEV;
357 		goto exit;
358 	}
359 
360 	/* lock our device */
361 	down(&dev->sem); /* not interruptible */
362 
363 	if (dev->open_count <= 0) {
364 		dbg(1," %s : device not opened", __FUNCTION__);
365 		retval = -ENODEV;
366 		goto exit;
367 	}
368 
369 	/* do the work */
370 	retval = adu_release_internal(dev);
371 
372 exit:
373 	if (dev)
374 		up(&dev->sem);
375 	dbg(2," %s : leave, return value %d", __FUNCTION__, retval);
376 	return retval;
377 }
378 
379 static ssize_t adu_read(struct file *file, __user char *buffer, size_t count,
380 			loff_t *ppos)
381 {
382 	struct adu_device *dev;
383 	size_t bytes_read = 0;
384 	size_t bytes_to_read = count;
385 	int i;
386 	int retval = 0;
387 	int timeout = 0;
388 	int should_submit = 0;
389 	unsigned long flags;
390 	DECLARE_WAITQUEUE(wait, current);
391 
392 	dbg(2," %s : enter, count = %Zd, file=%p", __FUNCTION__, count, file);
393 
394 	dev = file->private_data;
395 	dbg(2," %s : dev=%p", __FUNCTION__, dev);
396 	/* lock this object */
397 	if (down_interruptible(&dev->sem))
398 		return -ERESTARTSYS;
399 
400 	/* verify that the device wasn't unplugged */
401 	if (dev->udev == NULL || dev->minor == 0) {
402 		retval = -ENODEV;
403 		err("No device or device unplugged %d", retval);
404 		goto exit;
405 	}
406 
407 	/* verify that some data was requested */
408 	if (count == 0) {
409 		dbg(1," %s : read request of 0 bytes", __FUNCTION__);
410 		goto exit;
411 	}
412 
413 	timeout = COMMAND_TIMEOUT;
414 	dbg(2," %s : about to start looping", __FUNCTION__);
415 	while (bytes_to_read) {
416 		int data_in_secondary = dev->secondary_tail - dev->secondary_head;
417 		dbg(2," %s : while, data_in_secondary=%d, status=%d",
418 		    __FUNCTION__, data_in_secondary,
419 		    dev->interrupt_in_urb->status);
420 
421 		if (data_in_secondary) {
422 			/* drain secondary buffer */
423 			int amount = bytes_to_read < data_in_secondary ? bytes_to_read : data_in_secondary;
424 			i = copy_to_user(buffer, dev->read_buffer_secondary+dev->secondary_head, amount);
425 			if (i < 0) {
426 				retval = -EFAULT;
427 				goto exit;
428 			}
429 			dev->secondary_head += (amount - i);
430 			bytes_read += (amount - i);
431 			bytes_to_read -= (amount - i);
432 			if (i) {
433 				retval = bytes_read ? bytes_read : -EFAULT;
434 				goto exit;
435 			}
436 		} else {
437 			/* we check the primary buffer */
438 			spin_lock_irqsave (&dev->buflock, flags);
439 			if (dev->read_buffer_length) {
440 				/* we secure access to the primary */
441 				char *tmp;
442 				dbg(2," %s : swap, read_buffer_length = %d",
443 				    __FUNCTION__, dev->read_buffer_length);
444 				tmp = dev->read_buffer_secondary;
445 				dev->read_buffer_secondary = dev->read_buffer_primary;
446 				dev->read_buffer_primary = tmp;
447 				dev->secondary_head = 0;
448 				dev->secondary_tail = dev->read_buffer_length;
449 				dev->read_buffer_length = 0;
450 				spin_unlock_irqrestore(&dev->buflock, flags);
451 				/* we have a free buffer so use it */
452 				should_submit = 1;
453 			} else {
454 				/* even the primary was empty - we may need to do IO */
455 				if (dev->interrupt_in_urb->status == -EINPROGRESS) {
456 					/* somebody is doing IO */
457 					spin_unlock_irqrestore(&dev->buflock, flags);
458 					dbg(2," %s : submitted already", __FUNCTION__);
459 				} else {
460 					/* we must initiate input */
461 					dbg(2," %s : initiate input", __FUNCTION__);
462 					dev->read_urb_finished = 0;
463 
464 					usb_fill_int_urb(dev->interrupt_in_urb,dev->udev,
465 							 usb_rcvintpipe(dev->udev,
466 							 		dev->interrupt_in_endpoint->bEndpointAddress),
467 							 dev->interrupt_in_buffer,
468 							 le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize),
469 							 adu_interrupt_in_callback,
470 							 dev,
471 							 dev->interrupt_in_endpoint->bInterval);
472 					retval = usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
473 					if (!retval) {
474 						spin_unlock_irqrestore(&dev->buflock, flags);
475 						dbg(2," %s : submitted OK", __FUNCTION__);
476 					} else {
477 						if (retval == -ENOMEM) {
478 							retval = bytes_read ? bytes_read : -ENOMEM;
479 						}
480 						spin_unlock_irqrestore(&dev->buflock, flags);
481 						dbg(2," %s : submit failed", __FUNCTION__);
482 						goto exit;
483 					}
484 				}
485 
486 				/* we wait for I/O to complete */
487 				set_current_state(TASK_INTERRUPTIBLE);
488 				add_wait_queue(&dev->read_wait, &wait);
489 				if (!dev->read_urb_finished)
490 					timeout = schedule_timeout(COMMAND_TIMEOUT);
491 				else
492 					set_current_state(TASK_RUNNING);
493 				remove_wait_queue(&dev->read_wait, &wait);
494 
495 				if (timeout <= 0) {
496 					dbg(2," %s : timeout", __FUNCTION__);
497 					retval = bytes_read ? bytes_read : -ETIMEDOUT;
498 					goto exit;
499 				}
500 
501 				if (signal_pending(current)) {
502 					dbg(2," %s : signal pending", __FUNCTION__);
503 					retval = bytes_read ? bytes_read : -EINTR;
504 					goto exit;
505 				}
506 			}
507 		}
508 	}
509 
510 	retval = bytes_read;
511 	/* if the primary buffer is empty then use it */
512 	if (should_submit && !dev->interrupt_in_urb->status==-EINPROGRESS) {
513 		usb_fill_int_urb(dev->interrupt_in_urb,dev->udev,
514 				 usb_rcvintpipe(dev->udev,
515 				 		dev->interrupt_in_endpoint->bEndpointAddress),
516 						dev->interrupt_in_buffer,
517 						le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize),
518 						adu_interrupt_in_callback,
519 						dev,
520 						dev->interrupt_in_endpoint->bInterval);
521 		/* dev->interrupt_in_urb->transfer_flags |= URB_ASYNC_UNLINK; */
522 		dev->read_urb_finished = 0;
523 		usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
524 		/* we ignore failure */
525 	}
526 
527 exit:
528 	/* unlock the device */
529 	up(&dev->sem);
530 
531 	dbg(2," %s : leave, return value %d", __FUNCTION__, retval);
532 	return retval;
533 }
534 
535 static ssize_t adu_write(struct file *file, const __user char *buffer,
536 			 size_t count, loff_t *ppos)
537 {
538 	struct adu_device *dev;
539 	size_t bytes_written = 0;
540 	size_t bytes_to_write;
541 	size_t buffer_size;
542 	int retval = 0;
543 	int timeout = 0;
544 
545 	dbg(2," %s : enter, count = %Zd", __FUNCTION__, count);
546 
547 	dev = file->private_data;
548 
549 	/* lock this object */
550 	down_interruptible(&dev->sem);
551 
552 	/* verify that the device wasn't unplugged */
553 	if (dev->udev == NULL || dev->minor == 0) {
554 		retval = -ENODEV;
555 		err("No device or device unplugged %d", retval);
556 		goto exit;
557 	}
558 
559 	/* verify that we actually have some data to write */
560 	if (count == 0) {
561 		dbg(1," %s : write request of 0 bytes", __FUNCTION__);
562 		goto exit;
563 	}
564 
565 
566 	while (count > 0) {
567 		if (dev->interrupt_out_urb->status == -EINPROGRESS) {
568 			timeout = COMMAND_TIMEOUT;
569 
570 			while (timeout > 0) {
571 				if (signal_pending(current)) {
572 				dbg(1," %s : interrupted", __FUNCTION__);
573 				retval = -EINTR;
574 				goto exit;
575 			}
576 			up(&dev->sem);
577 			timeout = interruptible_sleep_on_timeout(&dev->write_wait, timeout);
578 			down_interruptible(&dev->sem);
579 			if (timeout > 0) {
580 				break;
581 			}
582 			dbg(1," %s : interrupted timeout: %d", __FUNCTION__, timeout);
583 		}
584 
585 
586 		dbg(1," %s : final timeout: %d", __FUNCTION__, timeout);
587 
588 		if (timeout == 0) {
589 			dbg(1, "%s - command timed out.", __FUNCTION__);
590 			retval = -ETIMEDOUT;
591 			goto exit;
592 		}
593 
594 		dbg(4," %s : in progress, count = %Zd", __FUNCTION__, count);
595 
596 		} else {
597 			dbg(4," %s : sending, count = %Zd", __FUNCTION__, count);
598 
599 			/* write the data into interrupt_out_buffer from userspace */
600 			buffer_size = le16_to_cpu(dev->interrupt_out_endpoint->wMaxPacketSize);
601 			bytes_to_write = count > buffer_size ? buffer_size : count;
602 			dbg(4," %s : buffer_size = %Zd, count = %Zd, bytes_to_write = %Zd",
603 			    __FUNCTION__, buffer_size, count, bytes_to_write);
604 
605 			if (copy_from_user(dev->interrupt_out_buffer, buffer, bytes_to_write) != 0) {
606 				retval = -EFAULT;
607 				goto exit;
608 			}
609 
610 			/* send off the urb */
611 			usb_fill_int_urb(
612 				dev->interrupt_out_urb,
613 				dev->udev,
614 				usb_sndintpipe(dev->udev, dev->interrupt_out_endpoint->bEndpointAddress),
615 				dev->interrupt_out_buffer,
616 				bytes_to_write,
617 				adu_interrupt_out_callback,
618 				dev,
619 				dev->interrupt_in_endpoint->bInterval);
620 			/* dev->interrupt_in_urb->transfer_flags |= URB_ASYNC_UNLINK; */
621 			dev->interrupt_out_urb->actual_length = bytes_to_write;
622 			retval = usb_submit_urb(dev->interrupt_out_urb, GFP_KERNEL);
623 			if (retval < 0) {
624 				err("Couldn't submit interrupt_out_urb %d", retval);
625 				goto exit;
626 			}
627 
628 			buffer += bytes_to_write;
629 			count -= bytes_to_write;
630 
631 			bytes_written += bytes_to_write;
632 		}
633 	}
634 
635 	retval = bytes_written;
636 
637 exit:
638 	/* unlock the device */
639 	up(&dev->sem);
640 
641 	dbg(2," %s : leave, return value %d", __FUNCTION__, retval);
642 
643 	return retval;
644 }
645 
646 /* file operations needed when we register this driver */
647 static const struct file_operations adu_fops = {
648 	.owner = THIS_MODULE,
649 	.read  = adu_read,
650 	.write = adu_write,
651 	.open = adu_open,
652 	.release = adu_release,
653 };
654 
655 /*
656  * usb class driver info in order to get a minor number from the usb core,
657  * and to have the device registered with devfs and the driver core
658  */
659 static struct usb_class_driver adu_class = {
660 	.name = "usb/adutux%d",
661 	.fops = &adu_fops,
662 	.minor_base = ADU_MINOR_BASE,
663 };
664 
665 /**
666  * adu_probe
667  *
668  * Called by the usb core when a new device is connected that it thinks
669  * this driver might be interested in.
670  */
671 static int adu_probe(struct usb_interface *interface,
672 		     const struct usb_device_id *id)
673 {
674 	struct usb_device *udev = interface_to_usbdev(interface);
675 	struct adu_device *dev = NULL;
676 	struct usb_host_interface *iface_desc;
677 	struct usb_endpoint_descriptor *endpoint;
678 	int retval = -ENODEV;
679 	int in_end_size;
680 	int out_end_size;
681 	int i;
682 
683 	dbg(2," %s : enter", __FUNCTION__);
684 
685 	if (udev == NULL) {
686 		dev_err(&interface->dev, "udev is NULL.\n");
687 		goto exit;
688 	}
689 
690 	/* allocate memory for our device state and intialize it */
691 	dev = kzalloc(sizeof(struct adu_device), GFP_KERNEL);
692 	if (dev == NULL) {
693 		dev_err(&interface->dev, "Out of memory\n");
694 		retval = -ENOMEM;
695 		goto exit;
696 	}
697 
698 	init_MUTEX(&dev->sem);
699 	spin_lock_init(&dev->buflock);
700 	dev->udev = udev;
701 	init_waitqueue_head(&dev->read_wait);
702 	init_waitqueue_head(&dev->write_wait);
703 
704 	iface_desc = &interface->altsetting[0];
705 
706 	/* set up the endpoint information */
707 	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
708 		endpoint = &iface_desc->endpoint[i].desc;
709 
710 		if (usb_endpoint_is_int_in(endpoint))
711 			dev->interrupt_in_endpoint = endpoint;
712 
713 		if (usb_endpoint_is_int_out(endpoint))
714 			dev->interrupt_out_endpoint = endpoint;
715 	}
716 	if (dev->interrupt_in_endpoint == NULL) {
717 		dev_err(&interface->dev, "interrupt in endpoint not found\n");
718 		goto error;
719 	}
720 	if (dev->interrupt_out_endpoint == NULL) {
721 		dev_err(&interface->dev, "interrupt out endpoint not found\n");
722 		goto error;
723 	}
724 
725 	in_end_size = le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize);
726 	out_end_size = le16_to_cpu(dev->interrupt_out_endpoint->wMaxPacketSize);
727 
728 	dev->read_buffer_primary = kmalloc((4 * in_end_size), GFP_KERNEL);
729 	if (!dev->read_buffer_primary) {
730 		dev_err(&interface->dev, "Couldn't allocate read_buffer_primary\n");
731 		retval = -ENOMEM;
732 		goto error;
733 	}
734 
735 	/* debug code prime the buffer */
736 	memset(dev->read_buffer_primary, 'a', in_end_size);
737 	memset(dev->read_buffer_primary + in_end_size, 'b', in_end_size);
738 	memset(dev->read_buffer_primary + (2 * in_end_size), 'c', in_end_size);
739 	memset(dev->read_buffer_primary + (3 * in_end_size), 'd', in_end_size);
740 
741 	dev->read_buffer_secondary = kmalloc((4 * in_end_size), GFP_KERNEL);
742 	if (!dev->read_buffer_secondary) {
743 		dev_err(&interface->dev, "Couldn't allocate read_buffer_secondary\n");
744 		retval = -ENOMEM;
745 		goto error;
746 	}
747 
748 	/* debug code prime the buffer */
749 	memset(dev->read_buffer_secondary, 'e', in_end_size);
750 	memset(dev->read_buffer_secondary + in_end_size, 'f', in_end_size);
751 	memset(dev->read_buffer_secondary + (2 * in_end_size), 'g', in_end_size);
752 	memset(dev->read_buffer_secondary + (3 * in_end_size), 'h', in_end_size);
753 
754 	dev->interrupt_in_buffer = kmalloc(in_end_size, GFP_KERNEL);
755 	if (!dev->interrupt_in_buffer) {
756 		dev_err(&interface->dev, "Couldn't allocate interrupt_in_buffer\n");
757 		goto error;
758 	}
759 
760 	/* debug code prime the buffer */
761 	memset(dev->interrupt_in_buffer, 'i', in_end_size);
762 
763 	dev->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
764 	if (!dev->interrupt_in_urb) {
765 		dev_err(&interface->dev, "Couldn't allocate interrupt_in_urb\n");
766 		goto error;
767 	}
768 	dev->interrupt_out_buffer = kmalloc(out_end_size, GFP_KERNEL);
769 	if (!dev->interrupt_out_buffer) {
770 		dev_err(&interface->dev, "Couldn't allocate interrupt_out_buffer\n");
771 		goto error;
772 	}
773 	dev->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
774 	if (!dev->interrupt_out_urb) {
775 		dev_err(&interface->dev, "Couldn't allocate interrupt_out_urb\n");
776 		goto error;
777 	}
778 
779 	if (!usb_string(udev, udev->descriptor.iSerialNumber, dev->serial_number,
780 			sizeof(dev->serial_number))) {
781 		dev_err(&interface->dev, "Could not retrieve serial number\n");
782 		goto error;
783 	}
784 	dbg(2," %s : serial_number=%s", __FUNCTION__, dev->serial_number);
785 
786 	/* we can register the device now, as it is ready */
787 	usb_set_intfdata(interface, dev);
788 
789 	retval = usb_register_dev(interface, &adu_class);
790 
791 	if (retval) {
792 		/* something prevented us from registering this driver */
793 		dev_err(&interface->dev, "Not able to get a minor for this device.\n");
794 		usb_set_intfdata(interface, NULL);
795 		goto error;
796 	}
797 
798 	dev->minor = interface->minor;
799 
800 	/* let the user know what node this device is now attached to */
801 	dev_info(&interface->dev, "ADU%d %s now attached to /dev/usb/adutux%d",
802 		 udev->descriptor.idProduct, dev->serial_number,
803 		 (dev->minor - ADU_MINOR_BASE));
804 exit:
805 	dbg(2," %s : leave, return value %p (dev)", __FUNCTION__, dev);
806 
807 	return retval;
808 
809 error:
810 	adu_delete(dev);
811 	return retval;
812 }
813 
814 /**
815  * adu_disconnect
816  *
817  * Called by the usb core when the device is removed from the system.
818  */
819 static void adu_disconnect(struct usb_interface *interface)
820 {
821 	struct adu_device *dev;
822 	int minor;
823 
824 	dbg(2," %s : enter", __FUNCTION__);
825 
826 	mutex_lock(&disconnect_mutex); /* not interruptible */
827 
828 	dev = usb_get_intfdata(interface);
829 	usb_set_intfdata(interface, NULL);
830 
831 	down(&dev->sem); /* not interruptible */
832 
833 	minor = dev->minor;
834 
835 	/* give back our minor */
836 	usb_deregister_dev(interface, &adu_class);
837 	dev->minor = 0;
838 
839 	/* if the device is not opened, then we clean up right now */
840 	dbg(2," %s : open count %d", __FUNCTION__, dev->open_count);
841 	if (!dev->open_count) {
842 		up(&dev->sem);
843 		adu_delete(dev);
844 	} else {
845 		dev->udev = NULL;
846 		up(&dev->sem);
847 	}
848 
849 	mutex_unlock(&disconnect_mutex);
850 
851 	dev_info(&interface->dev, "ADU device adutux%d now disconnected",
852 		 (minor - ADU_MINOR_BASE));
853 
854 	dbg(2," %s : leave", __FUNCTION__);
855 }
856 
857 /* usb specific object needed to register this driver with the usb subsystem */
858 static struct usb_driver adu_driver = {
859 	.name = "adutux",
860 	.probe = adu_probe,
861 	.disconnect = adu_disconnect,
862 	.id_table = device_table,
863 };
864 
865 static int __init adu_init(void)
866 {
867 	int result;
868 
869 	dbg(2," %s : enter", __FUNCTION__);
870 
871 	/* register this driver with the USB subsystem */
872 	result = usb_register(&adu_driver);
873 	if (result < 0) {
874 		err("usb_register failed for the "__FILE__" driver. "
875 		    "Error number %d", result);
876 		goto exit;
877 	}
878 
879 	info("adutux " DRIVER_DESC " " DRIVER_VERSION);
880 	info("adutux is an experimental driver. Use at your own risk");
881 
882 exit:
883 	dbg(2," %s : leave, return value %d", __FUNCTION__, result);
884 
885 	return result;
886 }
887 
888 static void __exit adu_exit(void)
889 {
890 	dbg(2," %s : enter", __FUNCTION__);
891 	/* deregister this driver with the USB subsystem */
892 	usb_deregister(&adu_driver);
893 	dbg(2," %s : leave", __FUNCTION__);
894 }
895 
896 module_init(adu_init);
897 module_exit(adu_exit);
898 
899 MODULE_AUTHOR(DRIVER_AUTHOR);
900 MODULE_DESCRIPTION(DRIVER_DESC);
901 MODULE_LICENSE("GPL");
902