xref: /linux/drivers/usb/misc/legousbtower.c (revision d91517839e5d95adc0cf4b28caa7af62a71de526)
1 /*
2  * LEGO USB Tower driver
3  *
4  * Copyright (C) 2003 David Glance <davidgsf@sourceforge.net>
5  *               2001-2004 Juergen Stuber <starblue@users.sourceforge.net>
6  *
7  *	This program is free software; you can redistribute it and/or
8  *	modify it under the terms of the GNU General Public License as
9  *	published by the Free Software Foundation; either version 2 of
10  *	the License, or (at your option) any later version.
11  *
12  * derived from USB Skeleton driver - 0.5
13  * Copyright (C) 2001 Greg Kroah-Hartman (greg@kroah.com)
14  *
15  * History:
16  *
17  * 2001-10-13 - 0.1 js
18  *   - first version
19  * 2001-11-03 - 0.2 js
20  *   - simplified buffering, one-shot URBs for writing
21  * 2001-11-10 - 0.3 js
22  *   - removed IOCTL (setting power/mode is more complicated, postponed)
23  * 2001-11-28 - 0.4 js
24  *   - added vendor commands for mode of operation and power level in open
25  * 2001-12-04 - 0.5 js
26  *   - set IR mode by default (by oversight 0.4 set VLL mode)
27  * 2002-01-11 - 0.5? pcchan
28  *   - make read buffer reusable and work around bytes_to_write issue between
29  *     uhci and legusbtower
30  * 2002-09-23 - 0.52 david (david@csse.uwa.edu.au)
31  *   - imported into lejos project
32  *   - changed wake_up to wake_up_interruptible
33  *   - changed to use lego0 rather than tower0
34  *   - changed dbg() to use __func__ rather than deprecated __func__
35  * 2003-01-12 - 0.53 david (david@csse.uwa.edu.au)
36  *   - changed read and write to write everything or
37  *     timeout (from a patch by Chris Riesen and Brett Thaeler driver)
38  *   - added ioctl functionality to set timeouts
39  * 2003-07-18 - 0.54 davidgsf (david@csse.uwa.edu.au)
40  *   - initial import into LegoUSB project
41  *   - merge of existing LegoUSB.c driver
42  * 2003-07-18 - 0.56 davidgsf (david@csse.uwa.edu.au)
43  *   - port to 2.6 style driver
44  * 2004-02-29 - 0.6 Juergen Stuber <starblue@users.sourceforge.net>
45  *   - fix locking
46  *   - unlink read URBs which are no longer needed
47  *   - allow increased buffer size, eliminates need for timeout on write
48  *   - have read URB running continuously
49  *   - added poll
50  *   - forbid seeking
51  *   - added nonblocking I/O
52  *   - changed back __func__ to __func__
53  *   - read and log tower firmware version
54  *   - reset tower on probe, avoids failure of first write
55  * 2004-03-09 - 0.7 Juergen Stuber <starblue@users.sourceforge.net>
56  *   - timeout read now only after inactivity, shorten default accordingly
57  * 2004-03-11 - 0.8 Juergen Stuber <starblue@users.sourceforge.net>
58  *   - log major, minor instead of possibly confusing device filename
59  *   - whitespace cleanup
60  * 2004-03-12 - 0.9 Juergen Stuber <starblue@users.sourceforge.net>
61  *   - normalize whitespace in debug messages
62  *   - take care about endianness in control message responses
63  * 2004-03-13 - 0.91 Juergen Stuber <starblue@users.sourceforge.net>
64  *   - make default intervals longer to accommodate current EHCI driver
65  * 2004-03-19 - 0.92 Juergen Stuber <starblue@users.sourceforge.net>
66  *   - replaced atomic_t by memory barriers
67  * 2004-04-21 - 0.93 Juergen Stuber <starblue@users.sourceforge.net>
68  *   - wait for completion of write urb in release (needed for remotecontrol)
69  *   - corrected poll for write direction (missing negation)
70  * 2004-04-22 - 0.94 Juergen Stuber <starblue@users.sourceforge.net>
71  *   - make device locking interruptible
72  * 2004-04-30 - 0.95 Juergen Stuber <starblue@users.sourceforge.net>
73  *   - check for valid udev on resubmitting and unlinking urbs
74  * 2004-08-03 - 0.96 Juergen Stuber <starblue@users.sourceforge.net>
75  *   - move reset into open to clean out spurious data
76  */
77 
78 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
79 
80 #include <linux/kernel.h>
81 #include <linux/errno.h>
82 #include <linux/slab.h>
83 #include <linux/module.h>
84 #include <linux/completion.h>
85 #include <linux/mutex.h>
86 #include <asm/uaccess.h>
87 #include <linux/usb.h>
88 #include <linux/poll.h>
89 
90 
91 /* Version Information */
92 #define DRIVER_VERSION "v0.96"
93 #define DRIVER_AUTHOR "Juergen Stuber <starblue@sourceforge.net>"
94 #define DRIVER_DESC "LEGO USB Tower Driver"
95 
96 
97 /* The defaults are chosen to work with the latest versions of leJOS and NQC.
98  */
99 
100 /* Some legacy software likes to receive packets in one piece.
101  * In this case read_buffer_size should exceed the maximal packet length
102  * (417 for datalog uploads), and packet_timeout should be set.
103  */
104 static int read_buffer_size = 480;
105 module_param(read_buffer_size, int, 0);
106 MODULE_PARM_DESC(read_buffer_size, "Read buffer size");
107 
108 /* Some legacy software likes to send packets in one piece.
109  * In this case write_buffer_size should exceed the maximal packet length
110  * (417 for firmware and program downloads).
111  * A problem with long writes is that the following read may time out
112  * if the software is not prepared to wait long enough.
113  */
114 static int write_buffer_size = 480;
115 module_param(write_buffer_size, int, 0);
116 MODULE_PARM_DESC(write_buffer_size, "Write buffer size");
117 
118 /* Some legacy software expects reads to contain whole LASM packets.
119  * To achieve this, characters which arrive before a packet timeout
120  * occurs will be returned in a single read operation.
121  * A problem with long reads is that the software may time out
122  * if it is not prepared to wait long enough.
123  * The packet timeout should be greater than the time between the
124  * reception of subsequent characters, which should arrive about
125  * every 5ms for the standard 2400 baud.
126  * Set it to 0 to disable.
127  */
128 static int packet_timeout = 50;
129 module_param(packet_timeout, int, 0);
130 MODULE_PARM_DESC(packet_timeout, "Packet timeout in ms");
131 
132 /* Some legacy software expects blocking reads to time out.
133  * Timeout occurs after the specified time of read and write inactivity.
134  * Set it to 0 to disable.
135  */
136 static int read_timeout = 200;
137 module_param(read_timeout, int, 0);
138 MODULE_PARM_DESC(read_timeout, "Read timeout in ms");
139 
140 /* As of kernel version 2.6.4 ehci-hcd uses an
141  * "only one interrupt transfer per frame" shortcut
142  * to simplify the scheduling of periodic transfers.
143  * This conflicts with our standard 1ms intervals for in and out URBs.
144  * We use default intervals of 2ms for in and 8ms for out transfers,
145  * which is fast enough for 2400 baud and allows a small additional load.
146  * Increase the interval to allow more devices that do interrupt transfers,
147  * or set to 0 to use the standard interval from the endpoint descriptors.
148  */
149 static int interrupt_in_interval = 2;
150 module_param(interrupt_in_interval, int, 0);
151 MODULE_PARM_DESC(interrupt_in_interval, "Interrupt in interval in ms");
152 
153 static int interrupt_out_interval = 8;
154 module_param(interrupt_out_interval, int, 0);
155 MODULE_PARM_DESC(interrupt_out_interval, "Interrupt out interval in ms");
156 
157 /* Define these values to match your device */
158 #define LEGO_USB_TOWER_VENDOR_ID	0x0694
159 #define LEGO_USB_TOWER_PRODUCT_ID	0x0001
160 
161 /* Vendor requests */
162 #define LEGO_USB_TOWER_REQUEST_RESET		0x04
163 #define LEGO_USB_TOWER_REQUEST_GET_VERSION	0xFD
164 
165 struct tower_reset_reply {
166 	__le16 size;		/* little-endian */
167 	__u8 err_code;
168 	__u8 spare;
169 } __attribute__ ((packed));
170 
171 struct tower_get_version_reply {
172 	__le16 size;		/* little-endian */
173 	__u8 err_code;
174 	__u8 spare;
175 	__u8 major;
176 	__u8 minor;
177 	__le16 build_no;		/* little-endian */
178 } __attribute__ ((packed));
179 
180 
181 /* table of devices that work with this driver */
182 static const struct usb_device_id tower_table[] = {
183 	{ USB_DEVICE(LEGO_USB_TOWER_VENDOR_ID, LEGO_USB_TOWER_PRODUCT_ID) },
184 	{ }					/* Terminating entry */
185 };
186 
187 MODULE_DEVICE_TABLE (usb, tower_table);
188 static DEFINE_MUTEX(open_disc_mutex);
189 
190 #define LEGO_USB_TOWER_MINOR_BASE	160
191 
192 
193 /* Structure to hold all of our device specific stuff */
194 struct lego_usb_tower {
195 	struct mutex		lock;		/* locks this structure */
196 	struct usb_device*	udev;		/* save off the usb device pointer */
197 	unsigned char		minor;		/* the starting minor number for this device */
198 
199 	int			open_count;	/* number of times this port has been opened */
200 
201 	char*			read_buffer;
202 	size_t			read_buffer_length; /* this much came in */
203 	size_t			read_packet_length; /* this much will be returned on read */
204 	spinlock_t		read_buffer_lock;
205 	int			packet_timeout_jiffies;
206 	unsigned long		read_last_arrival;
207 
208 	wait_queue_head_t	read_wait;
209 	wait_queue_head_t	write_wait;
210 
211 	char*			interrupt_in_buffer;
212 	struct usb_endpoint_descriptor* interrupt_in_endpoint;
213 	struct urb*		interrupt_in_urb;
214 	int			interrupt_in_interval;
215 	int			interrupt_in_running;
216 	int			interrupt_in_done;
217 
218 	char*			interrupt_out_buffer;
219 	struct usb_endpoint_descriptor* interrupt_out_endpoint;
220 	struct urb*		interrupt_out_urb;
221 	int			interrupt_out_interval;
222 	int			interrupt_out_busy;
223 
224 };
225 
226 
227 /* local function prototypes */
228 static ssize_t tower_read	(struct file *file, char __user *buffer, size_t count, loff_t *ppos);
229 static ssize_t tower_write	(struct file *file, const char __user *buffer, size_t count, loff_t *ppos);
230 static inline void tower_delete (struct lego_usb_tower *dev);
231 static int tower_open		(struct inode *inode, struct file *file);
232 static int tower_release	(struct inode *inode, struct file *file);
233 static unsigned int tower_poll	(struct file *file, poll_table *wait);
234 static loff_t tower_llseek	(struct file *file, loff_t off, int whence);
235 
236 static void tower_abort_transfers (struct lego_usb_tower *dev);
237 static void tower_check_for_read_packet (struct lego_usb_tower *dev);
238 static void tower_interrupt_in_callback (struct urb *urb);
239 static void tower_interrupt_out_callback (struct urb *urb);
240 
241 static int  tower_probe	(struct usb_interface *interface, const struct usb_device_id *id);
242 static void tower_disconnect	(struct usb_interface *interface);
243 
244 
245 /* file operations needed when we register this driver */
246 static const struct file_operations tower_fops = {
247 	.owner =	THIS_MODULE,
248 	.read  =	tower_read,
249 	.write =	tower_write,
250 	.open =		tower_open,
251 	.release =	tower_release,
252 	.poll =		tower_poll,
253 	.llseek =	tower_llseek,
254 };
255 
256 static char *legousbtower_devnode(struct device *dev, umode_t *mode)
257 {
258 	return kasprintf(GFP_KERNEL, "usb/%s", dev_name(dev));
259 }
260 
261 /*
262  * usb class driver info in order to get a minor number from the usb core,
263  * and to have the device registered with the driver core
264  */
265 static struct usb_class_driver tower_class = {
266 	.name =		"legousbtower%d",
267 	.devnode = 	legousbtower_devnode,
268 	.fops =		&tower_fops,
269 	.minor_base =	LEGO_USB_TOWER_MINOR_BASE,
270 };
271 
272 
273 /* usb specific object needed to register this driver with the usb subsystem */
274 static struct usb_driver tower_driver = {
275 	.name =		"legousbtower",
276 	.probe =	tower_probe,
277 	.disconnect =	tower_disconnect,
278 	.id_table =	tower_table,
279 };
280 
281 
282 /**
283  *	lego_usb_tower_debug_data
284  */
285 static inline void lego_usb_tower_debug_data(struct device *dev,
286 					     const char *function, int size,
287 					     const unsigned char *data)
288 {
289 	dev_dbg(dev, "%s - length = %d, data = %*ph\n",
290 		function, size, size, data);
291 }
292 
293 
294 /**
295  *	tower_delete
296  */
297 static inline void tower_delete (struct lego_usb_tower *dev)
298 {
299 	tower_abort_transfers (dev);
300 
301 	/* free data structures */
302 	usb_free_urb(dev->interrupt_in_urb);
303 	usb_free_urb(dev->interrupt_out_urb);
304 	kfree (dev->read_buffer);
305 	kfree (dev->interrupt_in_buffer);
306 	kfree (dev->interrupt_out_buffer);
307 	kfree (dev);
308 }
309 
310 
311 /**
312  *	tower_open
313  */
314 static int tower_open (struct inode *inode, struct file *file)
315 {
316 	struct lego_usb_tower *dev = NULL;
317 	int subminor;
318 	int retval = 0;
319 	struct usb_interface *interface;
320 	struct tower_reset_reply reset_reply;
321 	int result;
322 
323 	nonseekable_open(inode, file);
324 	subminor = iminor(inode);
325 
326 	interface = usb_find_interface (&tower_driver, subminor);
327 
328 	if (!interface) {
329 		pr_err("error, can't find device for minor %d\n", subminor);
330 		retval = -ENODEV;
331 		goto exit;
332 	}
333 
334 	mutex_lock(&open_disc_mutex);
335 	dev = usb_get_intfdata(interface);
336 
337 	if (!dev) {
338 		mutex_unlock(&open_disc_mutex);
339 		retval = -ENODEV;
340 		goto exit;
341 	}
342 
343 	/* lock this device */
344 	if (mutex_lock_interruptible(&dev->lock)) {
345 		mutex_unlock(&open_disc_mutex);
346 	        retval = -ERESTARTSYS;
347 		goto exit;
348 	}
349 
350 
351 	/* allow opening only once */
352 	if (dev->open_count) {
353 		mutex_unlock(&open_disc_mutex);
354 		retval = -EBUSY;
355 		goto unlock_exit;
356 	}
357 	dev->open_count = 1;
358 	mutex_unlock(&open_disc_mutex);
359 
360 	/* reset the tower */
361 	result = usb_control_msg (dev->udev,
362 				  usb_rcvctrlpipe(dev->udev, 0),
363 				  LEGO_USB_TOWER_REQUEST_RESET,
364 				  USB_TYPE_VENDOR | USB_DIR_IN | USB_RECIP_DEVICE,
365 				  0,
366 				  0,
367 				  &reset_reply,
368 				  sizeof(reset_reply),
369 				  1000);
370 	if (result < 0) {
371 		dev_err(&dev->udev->dev,
372 			"LEGO USB Tower reset control request failed\n");
373 		retval = result;
374 		goto unlock_exit;
375 	}
376 
377 	/* initialize in direction */
378 	dev->read_buffer_length = 0;
379 	dev->read_packet_length = 0;
380 	usb_fill_int_urb (dev->interrupt_in_urb,
381 			  dev->udev,
382 			  usb_rcvintpipe(dev->udev, dev->interrupt_in_endpoint->bEndpointAddress),
383 			  dev->interrupt_in_buffer,
384 			  usb_endpoint_maxp(dev->interrupt_in_endpoint),
385 			  tower_interrupt_in_callback,
386 			  dev,
387 			  dev->interrupt_in_interval);
388 
389 	dev->interrupt_in_running = 1;
390 	dev->interrupt_in_done = 0;
391 	mb();
392 
393 	retval = usb_submit_urb (dev->interrupt_in_urb, GFP_KERNEL);
394 	if (retval) {
395 		dev_err(&dev->udev->dev,
396 			"Couldn't submit interrupt_in_urb %d\n", retval);
397 		dev->interrupt_in_running = 0;
398 		dev->open_count = 0;
399 		goto unlock_exit;
400 	}
401 
402 	/* save device in the file's private structure */
403 	file->private_data = dev;
404 
405 unlock_exit:
406 	mutex_unlock(&dev->lock);
407 
408 exit:
409 	return retval;
410 }
411 
412 /**
413  *	tower_release
414  */
415 static int tower_release (struct inode *inode, struct file *file)
416 {
417 	struct lego_usb_tower *dev;
418 	int retval = 0;
419 
420 	dev = file->private_data;
421 
422 	if (dev == NULL) {
423 		retval = -ENODEV;
424 		goto exit_nolock;
425 	}
426 
427 	mutex_lock(&open_disc_mutex);
428 	if (mutex_lock_interruptible(&dev->lock)) {
429 	        retval = -ERESTARTSYS;
430 		goto exit;
431 	}
432 
433 	if (dev->open_count != 1) {
434 		dev_dbg(&dev->udev->dev, "%s: device not opened exactly once\n",
435 			__func__);
436 		retval = -ENODEV;
437 		goto unlock_exit;
438 	}
439 	if (dev->udev == NULL) {
440 		/* the device was unplugged before the file was released */
441 
442 		/* unlock here as tower_delete frees dev */
443 		mutex_unlock(&dev->lock);
444 		tower_delete (dev);
445 		goto exit;
446 	}
447 
448 	/* wait until write transfer is finished */
449 	if (dev->interrupt_out_busy) {
450 		wait_event_interruptible_timeout (dev->write_wait, !dev->interrupt_out_busy, 2 * HZ);
451 	}
452 	tower_abort_transfers (dev);
453 	dev->open_count = 0;
454 
455 unlock_exit:
456 	mutex_unlock(&dev->lock);
457 
458 exit:
459 	mutex_unlock(&open_disc_mutex);
460 exit_nolock:
461 	return retval;
462 }
463 
464 
465 /**
466  *	tower_abort_transfers
467  *      aborts transfers and frees associated data structures
468  */
469 static void tower_abort_transfers (struct lego_usb_tower *dev)
470 {
471 	if (dev == NULL)
472 		return;
473 
474 	/* shutdown transfer */
475 	if (dev->interrupt_in_running) {
476 		dev->interrupt_in_running = 0;
477 		mb();
478 		if (dev->udev)
479 			usb_kill_urb (dev->interrupt_in_urb);
480 	}
481 	if (dev->interrupt_out_busy && dev->udev)
482 		usb_kill_urb(dev->interrupt_out_urb);
483 }
484 
485 
486 /**
487  *	tower_check_for_read_packet
488  *
489  *      To get correct semantics for signals and non-blocking I/O
490  *      with packetizing we pretend not to see any data in the read buffer
491  *      until it has been there unchanged for at least
492  *      dev->packet_timeout_jiffies, or until the buffer is full.
493  */
494 static void tower_check_for_read_packet (struct lego_usb_tower *dev)
495 {
496 	spin_lock_irq (&dev->read_buffer_lock);
497 	if (!packet_timeout
498 	    || time_after(jiffies, dev->read_last_arrival + dev->packet_timeout_jiffies)
499 	    || dev->read_buffer_length == read_buffer_size) {
500 		dev->read_packet_length = dev->read_buffer_length;
501 	}
502 	dev->interrupt_in_done = 0;
503 	spin_unlock_irq (&dev->read_buffer_lock);
504 }
505 
506 
507 /**
508  *	tower_poll
509  */
510 static unsigned int tower_poll (struct file *file, poll_table *wait)
511 {
512 	struct lego_usb_tower *dev;
513 	unsigned int mask = 0;
514 
515 	dev = file->private_data;
516 
517 	if (!dev->udev)
518 		return POLLERR | POLLHUP;
519 
520 	poll_wait(file, &dev->read_wait, wait);
521 	poll_wait(file, &dev->write_wait, wait);
522 
523 	tower_check_for_read_packet(dev);
524 	if (dev->read_packet_length > 0) {
525 		mask |= POLLIN | POLLRDNORM;
526 	}
527 	if (!dev->interrupt_out_busy) {
528 		mask |= POLLOUT | POLLWRNORM;
529 	}
530 
531 	return mask;
532 }
533 
534 
535 /**
536  *	tower_llseek
537  */
538 static loff_t tower_llseek (struct file *file, loff_t off, int whence)
539 {
540 	return -ESPIPE;		/* unseekable */
541 }
542 
543 
544 /**
545  *	tower_read
546  */
547 static ssize_t tower_read (struct file *file, char __user *buffer, size_t count, loff_t *ppos)
548 {
549 	struct lego_usb_tower *dev;
550 	size_t bytes_to_read;
551 	int i;
552 	int retval = 0;
553 	unsigned long timeout = 0;
554 
555 	dev = file->private_data;
556 
557 	/* lock this object */
558 	if (mutex_lock_interruptible(&dev->lock)) {
559 		retval = -ERESTARTSYS;
560 		goto exit;
561 	}
562 
563 	/* verify that the device wasn't unplugged */
564 	if (dev->udev == NULL) {
565 		retval = -ENODEV;
566 		pr_err("No device or device unplugged %d\n", retval);
567 		goto unlock_exit;
568 	}
569 
570 	/* verify that we actually have some data to read */
571 	if (count == 0) {
572 		dev_dbg(&dev->udev->dev, "read request of 0 bytes\n");
573 		goto unlock_exit;
574 	}
575 
576 	if (read_timeout) {
577 		timeout = jiffies + read_timeout * HZ / 1000;
578 	}
579 
580 	/* wait for data */
581 	tower_check_for_read_packet (dev);
582 	while (dev->read_packet_length == 0) {
583 		if (file->f_flags & O_NONBLOCK) {
584 			retval = -EAGAIN;
585 			goto unlock_exit;
586 		}
587 		retval = wait_event_interruptible_timeout(dev->read_wait, dev->interrupt_in_done, dev->packet_timeout_jiffies);
588 		if (retval < 0) {
589 			goto unlock_exit;
590 		}
591 
592 		/* reset read timeout during read or write activity */
593 		if (read_timeout
594 		    && (dev->read_buffer_length || dev->interrupt_out_busy)) {
595 			timeout = jiffies + read_timeout * HZ / 1000;
596 		}
597 		/* check for read timeout */
598 		if (read_timeout && time_after (jiffies, timeout)) {
599 			retval = -ETIMEDOUT;
600 			goto unlock_exit;
601 		}
602 		tower_check_for_read_packet (dev);
603 	}
604 
605 	/* copy the data from read_buffer into userspace */
606 	bytes_to_read = min(count, dev->read_packet_length);
607 
608 	if (copy_to_user (buffer, dev->read_buffer, bytes_to_read)) {
609 		retval = -EFAULT;
610 		goto unlock_exit;
611 	}
612 
613 	spin_lock_irq (&dev->read_buffer_lock);
614 	dev->read_buffer_length -= bytes_to_read;
615 	dev->read_packet_length -= bytes_to_read;
616 	for (i=0; i<dev->read_buffer_length; i++) {
617 		dev->read_buffer[i] = dev->read_buffer[i+bytes_to_read];
618 	}
619 	spin_unlock_irq (&dev->read_buffer_lock);
620 
621 	retval = bytes_to_read;
622 
623 unlock_exit:
624 	/* unlock the device */
625 	mutex_unlock(&dev->lock);
626 
627 exit:
628 	return retval;
629 }
630 
631 
632 /**
633  *	tower_write
634  */
635 static ssize_t tower_write (struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
636 {
637 	struct lego_usb_tower *dev;
638 	size_t bytes_to_write;
639 	int retval = 0;
640 
641 	dev = file->private_data;
642 
643 	/* lock this object */
644 	if (mutex_lock_interruptible(&dev->lock)) {
645 		retval = -ERESTARTSYS;
646 		goto exit;
647 	}
648 
649 	/* verify that the device wasn't unplugged */
650 	if (dev->udev == NULL) {
651 		retval = -ENODEV;
652 		pr_err("No device or device unplugged %d\n", retval);
653 		goto unlock_exit;
654 	}
655 
656 	/* verify that we actually have some data to write */
657 	if (count == 0) {
658 		dev_dbg(&dev->udev->dev, "write request of 0 bytes\n");
659 		goto unlock_exit;
660 	}
661 
662 	/* wait until previous transfer is finished */
663 	while (dev->interrupt_out_busy) {
664 		if (file->f_flags & O_NONBLOCK) {
665 			retval = -EAGAIN;
666 			goto unlock_exit;
667 		}
668 		retval = wait_event_interruptible (dev->write_wait, !dev->interrupt_out_busy);
669 		if (retval) {
670 			goto unlock_exit;
671 		}
672 	}
673 
674 	/* write the data into interrupt_out_buffer from userspace */
675 	bytes_to_write = min_t(int, count, write_buffer_size);
676 	dev_dbg(&dev->udev->dev, "%s: count = %Zd, bytes_to_write = %Zd\n",
677 		__func__, count, bytes_to_write);
678 
679 	if (copy_from_user (dev->interrupt_out_buffer, buffer, bytes_to_write)) {
680 		retval = -EFAULT;
681 		goto unlock_exit;
682 	}
683 
684 	/* send off the urb */
685 	usb_fill_int_urb(dev->interrupt_out_urb,
686 			 dev->udev,
687 			 usb_sndintpipe(dev->udev, dev->interrupt_out_endpoint->bEndpointAddress),
688 			 dev->interrupt_out_buffer,
689 			 bytes_to_write,
690 			 tower_interrupt_out_callback,
691 			 dev,
692 			 dev->interrupt_out_interval);
693 
694 	dev->interrupt_out_busy = 1;
695 	wmb();
696 
697 	retval = usb_submit_urb (dev->interrupt_out_urb, GFP_KERNEL);
698 	if (retval) {
699 		dev->interrupt_out_busy = 0;
700 		dev_err(&dev->udev->dev,
701 			"Couldn't submit interrupt_out_urb %d\n", retval);
702 		goto unlock_exit;
703 	}
704 	retval = bytes_to_write;
705 
706 unlock_exit:
707 	/* unlock the device */
708 	mutex_unlock(&dev->lock);
709 
710 exit:
711 	return retval;
712 }
713 
714 
715 /**
716  *	tower_interrupt_in_callback
717  */
718 static void tower_interrupt_in_callback (struct urb *urb)
719 {
720 	struct lego_usb_tower *dev = urb->context;
721 	int status = urb->status;
722 	int retval;
723 
724 	lego_usb_tower_debug_data(&dev->udev->dev, __func__,
725 				  urb->actual_length, urb->transfer_buffer);
726 
727 	if (status) {
728 		if (status == -ENOENT ||
729 		    status == -ECONNRESET ||
730 		    status == -ESHUTDOWN) {
731 			goto exit;
732 		} else {
733 			dev_dbg(&dev->udev->dev,
734 				"%s: nonzero status received: %d\n", __func__,
735 				status);
736 			goto resubmit; /* maybe we can recover */
737 		}
738 	}
739 
740 	if (urb->actual_length > 0) {
741 		spin_lock (&dev->read_buffer_lock);
742 		if (dev->read_buffer_length + urb->actual_length < read_buffer_size) {
743 			memcpy (dev->read_buffer + dev->read_buffer_length,
744 				dev->interrupt_in_buffer,
745 				urb->actual_length);
746 			dev->read_buffer_length += urb->actual_length;
747 			dev->read_last_arrival = jiffies;
748 			dev_dbg(&dev->udev->dev, "%s: received %d bytes\n",
749 				__func__, urb->actual_length);
750 		} else {
751 			pr_warn("read_buffer overflow, %d bytes dropped\n",
752 				urb->actual_length);
753 		}
754 		spin_unlock (&dev->read_buffer_lock);
755 	}
756 
757 resubmit:
758 	/* resubmit if we're still running */
759 	if (dev->interrupt_in_running && dev->udev) {
760 		retval = usb_submit_urb (dev->interrupt_in_urb, GFP_ATOMIC);
761 		if (retval)
762 			dev_err(&dev->udev->dev,
763 				"%s: usb_submit_urb failed (%d)\n",
764 				__func__, retval);
765 	}
766 
767 exit:
768 	dev->interrupt_in_done = 1;
769 	wake_up_interruptible (&dev->read_wait);
770 }
771 
772 
773 /**
774  *	tower_interrupt_out_callback
775  */
776 static void tower_interrupt_out_callback (struct urb *urb)
777 {
778 	struct lego_usb_tower *dev = urb->context;
779 	int status = urb->status;
780 
781 	lego_usb_tower_debug_data(&dev->udev->dev, __func__,
782 				  urb->actual_length, urb->transfer_buffer);
783 
784 	/* sync/async unlink faults aren't errors */
785 	if (status && !(status == -ENOENT ||
786 			status == -ECONNRESET ||
787 			status == -ESHUTDOWN)) {
788 		dev_dbg(&dev->udev->dev,
789 			"%s: nonzero write bulk status received: %d\n", __func__,
790 			status);
791 	}
792 
793 	dev->interrupt_out_busy = 0;
794 	wake_up_interruptible(&dev->write_wait);
795 }
796 
797 
798 /**
799  *	tower_probe
800  *
801  *	Called by the usb core when a new device is connected that it thinks
802  *	this driver might be interested in.
803  */
804 static int tower_probe (struct usb_interface *interface, const struct usb_device_id *id)
805 {
806 	struct device *idev = &interface->dev;
807 	struct usb_device *udev = interface_to_usbdev(interface);
808 	struct lego_usb_tower *dev = NULL;
809 	struct usb_host_interface *iface_desc;
810 	struct usb_endpoint_descriptor* endpoint;
811 	struct tower_get_version_reply get_version_reply;
812 	int i;
813 	int retval = -ENOMEM;
814 	int result;
815 
816 	/* allocate memory for our device state and initialize it */
817 
818 	dev = kmalloc (sizeof(struct lego_usb_tower), GFP_KERNEL);
819 
820 	if (dev == NULL) {
821 		dev_err(idev, "Out of memory\n");
822 		goto exit;
823 	}
824 
825 	mutex_init(&dev->lock);
826 
827 	dev->udev = udev;
828 	dev->open_count = 0;
829 
830 	dev->read_buffer = NULL;
831 	dev->read_buffer_length = 0;
832 	dev->read_packet_length = 0;
833 	spin_lock_init (&dev->read_buffer_lock);
834 	dev->packet_timeout_jiffies = packet_timeout * HZ / 1000;
835 	dev->read_last_arrival = jiffies;
836 
837 	init_waitqueue_head (&dev->read_wait);
838 	init_waitqueue_head (&dev->write_wait);
839 
840 	dev->interrupt_in_buffer = NULL;
841 	dev->interrupt_in_endpoint = NULL;
842 	dev->interrupt_in_urb = NULL;
843 	dev->interrupt_in_running = 0;
844 	dev->interrupt_in_done = 0;
845 
846 	dev->interrupt_out_buffer = NULL;
847 	dev->interrupt_out_endpoint = NULL;
848 	dev->interrupt_out_urb = NULL;
849 	dev->interrupt_out_busy = 0;
850 
851 	iface_desc = interface->cur_altsetting;
852 
853 	/* set up the endpoint information */
854 	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
855 		endpoint = &iface_desc->endpoint[i].desc;
856 
857 		if (usb_endpoint_xfer_int(endpoint)) {
858 			if (usb_endpoint_dir_in(endpoint))
859 				dev->interrupt_in_endpoint = endpoint;
860 			else
861 				dev->interrupt_out_endpoint = endpoint;
862 		}
863 	}
864 	if(dev->interrupt_in_endpoint == NULL) {
865 		dev_err(idev, "interrupt in endpoint not found\n");
866 		goto error;
867 	}
868 	if (dev->interrupt_out_endpoint == NULL) {
869 		dev_err(idev, "interrupt out endpoint not found\n");
870 		goto error;
871 	}
872 
873 	dev->read_buffer = kmalloc (read_buffer_size, GFP_KERNEL);
874 	if (!dev->read_buffer) {
875 		dev_err(idev, "Couldn't allocate read_buffer\n");
876 		goto error;
877 	}
878 	dev->interrupt_in_buffer = kmalloc (usb_endpoint_maxp(dev->interrupt_in_endpoint), GFP_KERNEL);
879 	if (!dev->interrupt_in_buffer) {
880 		dev_err(idev, "Couldn't allocate interrupt_in_buffer\n");
881 		goto error;
882 	}
883 	dev->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
884 	if (!dev->interrupt_in_urb) {
885 		dev_err(idev, "Couldn't allocate interrupt_in_urb\n");
886 		goto error;
887 	}
888 	dev->interrupt_out_buffer = kmalloc (write_buffer_size, GFP_KERNEL);
889 	if (!dev->interrupt_out_buffer) {
890 		dev_err(idev, "Couldn't allocate interrupt_out_buffer\n");
891 		goto error;
892 	}
893 	dev->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
894 	if (!dev->interrupt_out_urb) {
895 		dev_err(idev, "Couldn't allocate interrupt_out_urb\n");
896 		goto error;
897 	}
898 	dev->interrupt_in_interval = interrupt_in_interval ? interrupt_in_interval : dev->interrupt_in_endpoint->bInterval;
899 	dev->interrupt_out_interval = interrupt_out_interval ? interrupt_out_interval : dev->interrupt_out_endpoint->bInterval;
900 
901 	/* we can register the device now, as it is ready */
902 	usb_set_intfdata (interface, dev);
903 
904 	retval = usb_register_dev (interface, &tower_class);
905 
906 	if (retval) {
907 		/* something prevented us from registering this driver */
908 		dev_err(idev, "Not able to get a minor for this device.\n");
909 		usb_set_intfdata (interface, NULL);
910 		goto error;
911 	}
912 	dev->minor = interface->minor;
913 
914 	/* let the user know what node this device is now attached to */
915 	dev_info(&interface->dev, "LEGO USB Tower #%d now attached to major "
916 		 "%d minor %d\n", (dev->minor - LEGO_USB_TOWER_MINOR_BASE),
917 		 USB_MAJOR, dev->minor);
918 
919 	/* get the firmware version and log it */
920 	result = usb_control_msg (udev,
921 				  usb_rcvctrlpipe(udev, 0),
922 				  LEGO_USB_TOWER_REQUEST_GET_VERSION,
923 				  USB_TYPE_VENDOR | USB_DIR_IN | USB_RECIP_DEVICE,
924 				  0,
925 				  0,
926 				  &get_version_reply,
927 				  sizeof(get_version_reply),
928 				  1000);
929 	if (result < 0) {
930 		dev_err(idev, "LEGO USB Tower get version control request failed\n");
931 		retval = result;
932 		goto error;
933 	}
934 	dev_info(&interface->dev, "LEGO USB Tower firmware version is %d.%d "
935 		 "build %d\n", get_version_reply.major,
936 		 get_version_reply.minor,
937 		 le16_to_cpu(get_version_reply.build_no));
938 
939 
940 exit:
941 	return retval;
942 
943 error:
944 	tower_delete(dev);
945 	return retval;
946 }
947 
948 
949 /**
950  *	tower_disconnect
951  *
952  *	Called by the usb core when the device is removed from the system.
953  */
954 static void tower_disconnect (struct usb_interface *interface)
955 {
956 	struct lego_usb_tower *dev;
957 	int minor;
958 
959 	dev = usb_get_intfdata (interface);
960 	mutex_lock(&open_disc_mutex);
961 	usb_set_intfdata (interface, NULL);
962 
963 	minor = dev->minor;
964 
965 	/* give back our minor */
966 	usb_deregister_dev (interface, &tower_class);
967 
968 	mutex_lock(&dev->lock);
969 	mutex_unlock(&open_disc_mutex);
970 
971 	/* if the device is not opened, then we clean up right now */
972 	if (!dev->open_count) {
973 		mutex_unlock(&dev->lock);
974 		tower_delete (dev);
975 	} else {
976 		dev->udev = NULL;
977 		/* wake up pollers */
978 		wake_up_interruptible_all(&dev->read_wait);
979 		wake_up_interruptible_all(&dev->write_wait);
980 		mutex_unlock(&dev->lock);
981 	}
982 
983 	dev_info(&interface->dev, "LEGO USB Tower #%d now disconnected\n",
984 		 (minor - LEGO_USB_TOWER_MINOR_BASE));
985 }
986 
987 module_usb_driver(tower_driver);
988 
989 MODULE_AUTHOR(DRIVER_AUTHOR);
990 MODULE_DESCRIPTION(DRIVER_DESC);
991 #ifdef MODULE_LICENSE
992 MODULE_LICENSE("GPL");
993 #endif
994