xref: /openbmc/linux/drivers/usb/misc/legousbtower.c (revision 5d0e4d78)
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 <linux/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 	reset_reply = kmalloc(sizeof(*reset_reply), GFP_KERNEL);
324 
325 	if (!reset_reply) {
326 		retval = -ENOMEM;
327 		goto exit;
328 	}
329 
330 	nonseekable_open(inode, file);
331 	subminor = iminor(inode);
332 
333 	interface = usb_find_interface (&tower_driver, subminor);
334 
335 	if (!interface) {
336 		pr_err("error, can't find device for minor %d\n", subminor);
337 		retval = -ENODEV;
338 		goto exit;
339 	}
340 
341 	mutex_lock(&open_disc_mutex);
342 	dev = usb_get_intfdata(interface);
343 
344 	if (!dev) {
345 		mutex_unlock(&open_disc_mutex);
346 		retval = -ENODEV;
347 		goto exit;
348 	}
349 
350 	/* lock this device */
351 	if (mutex_lock_interruptible(&dev->lock)) {
352 		mutex_unlock(&open_disc_mutex);
353 	        retval = -ERESTARTSYS;
354 		goto exit;
355 	}
356 
357 
358 	/* allow opening only once */
359 	if (dev->open_count) {
360 		mutex_unlock(&open_disc_mutex);
361 		retval = -EBUSY;
362 		goto unlock_exit;
363 	}
364 	dev->open_count = 1;
365 	mutex_unlock(&open_disc_mutex);
366 
367 	/* reset the tower */
368 	result = usb_control_msg (dev->udev,
369 				  usb_rcvctrlpipe(dev->udev, 0),
370 				  LEGO_USB_TOWER_REQUEST_RESET,
371 				  USB_TYPE_VENDOR | USB_DIR_IN | USB_RECIP_DEVICE,
372 				  0,
373 				  0,
374 				  reset_reply,
375 				  sizeof(*reset_reply),
376 				  1000);
377 	if (result < 0) {
378 		dev_err(&dev->udev->dev,
379 			"LEGO USB Tower reset control request failed\n");
380 		retval = result;
381 		goto unlock_exit;
382 	}
383 
384 	/* initialize in direction */
385 	dev->read_buffer_length = 0;
386 	dev->read_packet_length = 0;
387 	usb_fill_int_urb (dev->interrupt_in_urb,
388 			  dev->udev,
389 			  usb_rcvintpipe(dev->udev, dev->interrupt_in_endpoint->bEndpointAddress),
390 			  dev->interrupt_in_buffer,
391 			  usb_endpoint_maxp(dev->interrupt_in_endpoint),
392 			  tower_interrupt_in_callback,
393 			  dev,
394 			  dev->interrupt_in_interval);
395 
396 	dev->interrupt_in_running = 1;
397 	dev->interrupt_in_done = 0;
398 	mb();
399 
400 	retval = usb_submit_urb (dev->interrupt_in_urb, GFP_KERNEL);
401 	if (retval) {
402 		dev_err(&dev->udev->dev,
403 			"Couldn't submit interrupt_in_urb %d\n", retval);
404 		dev->interrupt_in_running = 0;
405 		dev->open_count = 0;
406 		goto unlock_exit;
407 	}
408 
409 	/* save device in the file's private structure */
410 	file->private_data = dev;
411 
412 unlock_exit:
413 	mutex_unlock(&dev->lock);
414 
415 exit:
416 	kfree(reset_reply);
417 	return retval;
418 }
419 
420 /**
421  *	tower_release
422  */
423 static int tower_release (struct inode *inode, struct file *file)
424 {
425 	struct lego_usb_tower *dev;
426 	int retval = 0;
427 
428 	dev = file->private_data;
429 
430 	if (dev == NULL) {
431 		retval = -ENODEV;
432 		goto exit_nolock;
433 	}
434 
435 	mutex_lock(&open_disc_mutex);
436 	if (mutex_lock_interruptible(&dev->lock)) {
437 	        retval = -ERESTARTSYS;
438 		goto exit;
439 	}
440 
441 	if (dev->open_count != 1) {
442 		dev_dbg(&dev->udev->dev, "%s: device not opened exactly once\n",
443 			__func__);
444 		retval = -ENODEV;
445 		goto unlock_exit;
446 	}
447 	if (dev->udev == NULL) {
448 		/* the device was unplugged before the file was released */
449 
450 		/* unlock here as tower_delete frees dev */
451 		mutex_unlock(&dev->lock);
452 		tower_delete (dev);
453 		goto exit;
454 	}
455 
456 	/* wait until write transfer is finished */
457 	if (dev->interrupt_out_busy) {
458 		wait_event_interruptible_timeout (dev->write_wait, !dev->interrupt_out_busy, 2 * HZ);
459 	}
460 	tower_abort_transfers (dev);
461 	dev->open_count = 0;
462 
463 unlock_exit:
464 	mutex_unlock(&dev->lock);
465 
466 exit:
467 	mutex_unlock(&open_disc_mutex);
468 exit_nolock:
469 	return retval;
470 }
471 
472 
473 /**
474  *	tower_abort_transfers
475  *      aborts transfers and frees associated data structures
476  */
477 static void tower_abort_transfers (struct lego_usb_tower *dev)
478 {
479 	if (dev == NULL)
480 		return;
481 
482 	/* shutdown transfer */
483 	if (dev->interrupt_in_running) {
484 		dev->interrupt_in_running = 0;
485 		mb();
486 		if (dev->udev)
487 			usb_kill_urb (dev->interrupt_in_urb);
488 	}
489 	if (dev->interrupt_out_busy && dev->udev)
490 		usb_kill_urb(dev->interrupt_out_urb);
491 }
492 
493 
494 /**
495  *	tower_check_for_read_packet
496  *
497  *      To get correct semantics for signals and non-blocking I/O
498  *      with packetizing we pretend not to see any data in the read buffer
499  *      until it has been there unchanged for at least
500  *      dev->packet_timeout_jiffies, or until the buffer is full.
501  */
502 static void tower_check_for_read_packet (struct lego_usb_tower *dev)
503 {
504 	spin_lock_irq (&dev->read_buffer_lock);
505 	if (!packet_timeout
506 	    || time_after(jiffies, dev->read_last_arrival + dev->packet_timeout_jiffies)
507 	    || dev->read_buffer_length == read_buffer_size) {
508 		dev->read_packet_length = dev->read_buffer_length;
509 	}
510 	dev->interrupt_in_done = 0;
511 	spin_unlock_irq (&dev->read_buffer_lock);
512 }
513 
514 
515 /**
516  *	tower_poll
517  */
518 static unsigned int tower_poll (struct file *file, poll_table *wait)
519 {
520 	struct lego_usb_tower *dev;
521 	unsigned int mask = 0;
522 
523 	dev = file->private_data;
524 
525 	if (!dev->udev)
526 		return POLLERR | POLLHUP;
527 
528 	poll_wait(file, &dev->read_wait, wait);
529 	poll_wait(file, &dev->write_wait, wait);
530 
531 	tower_check_for_read_packet(dev);
532 	if (dev->read_packet_length > 0) {
533 		mask |= POLLIN | POLLRDNORM;
534 	}
535 	if (!dev->interrupt_out_busy) {
536 		mask |= POLLOUT | POLLWRNORM;
537 	}
538 
539 	return mask;
540 }
541 
542 
543 /**
544  *	tower_llseek
545  */
546 static loff_t tower_llseek (struct file *file, loff_t off, int whence)
547 {
548 	return -ESPIPE;		/* unseekable */
549 }
550 
551 
552 /**
553  *	tower_read
554  */
555 static ssize_t tower_read (struct file *file, char __user *buffer, size_t count, loff_t *ppos)
556 {
557 	struct lego_usb_tower *dev;
558 	size_t bytes_to_read;
559 	int i;
560 	int retval = 0;
561 	unsigned long timeout = 0;
562 
563 	dev = file->private_data;
564 
565 	/* lock this object */
566 	if (mutex_lock_interruptible(&dev->lock)) {
567 		retval = -ERESTARTSYS;
568 		goto exit;
569 	}
570 
571 	/* verify that the device wasn't unplugged */
572 	if (dev->udev == NULL) {
573 		retval = -ENODEV;
574 		pr_err("No device or device unplugged %d\n", retval);
575 		goto unlock_exit;
576 	}
577 
578 	/* verify that we actually have some data to read */
579 	if (count == 0) {
580 		dev_dbg(&dev->udev->dev, "read request of 0 bytes\n");
581 		goto unlock_exit;
582 	}
583 
584 	if (read_timeout) {
585 		timeout = jiffies + msecs_to_jiffies(read_timeout);
586 	}
587 
588 	/* wait for data */
589 	tower_check_for_read_packet (dev);
590 	while (dev->read_packet_length == 0) {
591 		if (file->f_flags & O_NONBLOCK) {
592 			retval = -EAGAIN;
593 			goto unlock_exit;
594 		}
595 		retval = wait_event_interruptible_timeout(dev->read_wait, dev->interrupt_in_done, dev->packet_timeout_jiffies);
596 		if (retval < 0) {
597 			goto unlock_exit;
598 		}
599 
600 		/* reset read timeout during read or write activity */
601 		if (read_timeout
602 		    && (dev->read_buffer_length || dev->interrupt_out_busy)) {
603 			timeout = jiffies + msecs_to_jiffies(read_timeout);
604 		}
605 		/* check for read timeout */
606 		if (read_timeout && time_after (jiffies, timeout)) {
607 			retval = -ETIMEDOUT;
608 			goto unlock_exit;
609 		}
610 		tower_check_for_read_packet (dev);
611 	}
612 
613 	/* copy the data from read_buffer into userspace */
614 	bytes_to_read = min(count, dev->read_packet_length);
615 
616 	if (copy_to_user (buffer, dev->read_buffer, bytes_to_read)) {
617 		retval = -EFAULT;
618 		goto unlock_exit;
619 	}
620 
621 	spin_lock_irq (&dev->read_buffer_lock);
622 	dev->read_buffer_length -= bytes_to_read;
623 	dev->read_packet_length -= bytes_to_read;
624 	for (i=0; i<dev->read_buffer_length; i++) {
625 		dev->read_buffer[i] = dev->read_buffer[i+bytes_to_read];
626 	}
627 	spin_unlock_irq (&dev->read_buffer_lock);
628 
629 	retval = bytes_to_read;
630 
631 unlock_exit:
632 	/* unlock the device */
633 	mutex_unlock(&dev->lock);
634 
635 exit:
636 	return retval;
637 }
638 
639 
640 /**
641  *	tower_write
642  */
643 static ssize_t tower_write (struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
644 {
645 	struct lego_usb_tower *dev;
646 	size_t bytes_to_write;
647 	int retval = 0;
648 
649 	dev = file->private_data;
650 
651 	/* lock this object */
652 	if (mutex_lock_interruptible(&dev->lock)) {
653 		retval = -ERESTARTSYS;
654 		goto exit;
655 	}
656 
657 	/* verify that the device wasn't unplugged */
658 	if (dev->udev == NULL) {
659 		retval = -ENODEV;
660 		pr_err("No device or device unplugged %d\n", retval);
661 		goto unlock_exit;
662 	}
663 
664 	/* verify that we actually have some data to write */
665 	if (count == 0) {
666 		dev_dbg(&dev->udev->dev, "write request of 0 bytes\n");
667 		goto unlock_exit;
668 	}
669 
670 	/* wait until previous transfer is finished */
671 	while (dev->interrupt_out_busy) {
672 		if (file->f_flags & O_NONBLOCK) {
673 			retval = -EAGAIN;
674 			goto unlock_exit;
675 		}
676 		retval = wait_event_interruptible (dev->write_wait, !dev->interrupt_out_busy);
677 		if (retval) {
678 			goto unlock_exit;
679 		}
680 	}
681 
682 	/* write the data into interrupt_out_buffer from userspace */
683 	bytes_to_write = min_t(int, count, write_buffer_size);
684 	dev_dbg(&dev->udev->dev, "%s: count = %zd, bytes_to_write = %zd\n",
685 		__func__, count, bytes_to_write);
686 
687 	if (copy_from_user (dev->interrupt_out_buffer, buffer, bytes_to_write)) {
688 		retval = -EFAULT;
689 		goto unlock_exit;
690 	}
691 
692 	/* send off the urb */
693 	usb_fill_int_urb(dev->interrupt_out_urb,
694 			 dev->udev,
695 			 usb_sndintpipe(dev->udev, dev->interrupt_out_endpoint->bEndpointAddress),
696 			 dev->interrupt_out_buffer,
697 			 bytes_to_write,
698 			 tower_interrupt_out_callback,
699 			 dev,
700 			 dev->interrupt_out_interval);
701 
702 	dev->interrupt_out_busy = 1;
703 	wmb();
704 
705 	retval = usb_submit_urb (dev->interrupt_out_urb, GFP_KERNEL);
706 	if (retval) {
707 		dev->interrupt_out_busy = 0;
708 		dev_err(&dev->udev->dev,
709 			"Couldn't submit interrupt_out_urb %d\n", retval);
710 		goto unlock_exit;
711 	}
712 	retval = bytes_to_write;
713 
714 unlock_exit:
715 	/* unlock the device */
716 	mutex_unlock(&dev->lock);
717 
718 exit:
719 	return retval;
720 }
721 
722 
723 /**
724  *	tower_interrupt_in_callback
725  */
726 static void tower_interrupt_in_callback (struct urb *urb)
727 {
728 	struct lego_usb_tower *dev = urb->context;
729 	int status = urb->status;
730 	int retval;
731 
732 	lego_usb_tower_debug_data(&dev->udev->dev, __func__,
733 				  urb->actual_length, urb->transfer_buffer);
734 
735 	if (status) {
736 		if (status == -ENOENT ||
737 		    status == -ECONNRESET ||
738 		    status == -ESHUTDOWN) {
739 			goto exit;
740 		} else {
741 			dev_dbg(&dev->udev->dev,
742 				"%s: nonzero status received: %d\n", __func__,
743 				status);
744 			goto resubmit; /* maybe we can recover */
745 		}
746 	}
747 
748 	if (urb->actual_length > 0) {
749 		spin_lock (&dev->read_buffer_lock);
750 		if (dev->read_buffer_length + urb->actual_length < read_buffer_size) {
751 			memcpy (dev->read_buffer + dev->read_buffer_length,
752 				dev->interrupt_in_buffer,
753 				urb->actual_length);
754 			dev->read_buffer_length += urb->actual_length;
755 			dev->read_last_arrival = jiffies;
756 			dev_dbg(&dev->udev->dev, "%s: received %d bytes\n",
757 				__func__, urb->actual_length);
758 		} else {
759 			pr_warn("read_buffer overflow, %d bytes dropped\n",
760 				urb->actual_length);
761 		}
762 		spin_unlock (&dev->read_buffer_lock);
763 	}
764 
765 resubmit:
766 	/* resubmit if we're still running */
767 	if (dev->interrupt_in_running && dev->udev) {
768 		retval = usb_submit_urb (dev->interrupt_in_urb, GFP_ATOMIC);
769 		if (retval)
770 			dev_err(&dev->udev->dev,
771 				"%s: usb_submit_urb failed (%d)\n",
772 				__func__, retval);
773 	}
774 
775 exit:
776 	dev->interrupt_in_done = 1;
777 	wake_up_interruptible (&dev->read_wait);
778 }
779 
780 
781 /**
782  *	tower_interrupt_out_callback
783  */
784 static void tower_interrupt_out_callback (struct urb *urb)
785 {
786 	struct lego_usb_tower *dev = urb->context;
787 	int status = urb->status;
788 
789 	lego_usb_tower_debug_data(&dev->udev->dev, __func__,
790 				  urb->actual_length, urb->transfer_buffer);
791 
792 	/* sync/async unlink faults aren't errors */
793 	if (status && !(status == -ENOENT ||
794 			status == -ECONNRESET ||
795 			status == -ESHUTDOWN)) {
796 		dev_dbg(&dev->udev->dev,
797 			"%s: nonzero write bulk status received: %d\n", __func__,
798 			status);
799 	}
800 
801 	dev->interrupt_out_busy = 0;
802 	wake_up_interruptible(&dev->write_wait);
803 }
804 
805 
806 /**
807  *	tower_probe
808  *
809  *	Called by the usb core when a new device is connected that it thinks
810  *	this driver might be interested in.
811  */
812 static int tower_probe (struct usb_interface *interface, const struct usb_device_id *id)
813 {
814 	struct device *idev = &interface->dev;
815 	struct usb_device *udev = interface_to_usbdev(interface);
816 	struct lego_usb_tower *dev = NULL;
817 	struct tower_get_version_reply *get_version_reply = NULL;
818 	int retval = -ENOMEM;
819 	int result;
820 
821 	/* allocate memory for our device state and initialize it */
822 
823 	dev = kmalloc (sizeof(struct lego_usb_tower), GFP_KERNEL);
824 
825 	if (!dev)
826 		goto exit;
827 
828 	mutex_init(&dev->lock);
829 
830 	dev->udev = udev;
831 	dev->open_count = 0;
832 
833 	dev->read_buffer = NULL;
834 	dev->read_buffer_length = 0;
835 	dev->read_packet_length = 0;
836 	spin_lock_init (&dev->read_buffer_lock);
837 	dev->packet_timeout_jiffies = msecs_to_jiffies(packet_timeout);
838 	dev->read_last_arrival = jiffies;
839 
840 	init_waitqueue_head (&dev->read_wait);
841 	init_waitqueue_head (&dev->write_wait);
842 
843 	dev->interrupt_in_buffer = NULL;
844 	dev->interrupt_in_endpoint = NULL;
845 	dev->interrupt_in_urb = NULL;
846 	dev->interrupt_in_running = 0;
847 	dev->interrupt_in_done = 0;
848 
849 	dev->interrupt_out_buffer = NULL;
850 	dev->interrupt_out_endpoint = NULL;
851 	dev->interrupt_out_urb = NULL;
852 	dev->interrupt_out_busy = 0;
853 
854 	result = usb_find_common_endpoints_reverse(interface->cur_altsetting,
855 			NULL, NULL,
856 			&dev->interrupt_in_endpoint,
857 			&dev->interrupt_out_endpoint);
858 	if (result) {
859 		dev_err(idev, "interrupt endpoints not found\n");
860 		retval = result;
861 		goto error;
862 	}
863 
864 	dev->read_buffer = kmalloc (read_buffer_size, GFP_KERNEL);
865 	if (!dev->read_buffer)
866 		goto error;
867 	dev->interrupt_in_buffer = kmalloc (usb_endpoint_maxp(dev->interrupt_in_endpoint), GFP_KERNEL);
868 	if (!dev->interrupt_in_buffer)
869 		goto error;
870 	dev->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
871 	if (!dev->interrupt_in_urb)
872 		goto error;
873 	dev->interrupt_out_buffer = kmalloc (write_buffer_size, GFP_KERNEL);
874 	if (!dev->interrupt_out_buffer)
875 		goto error;
876 	dev->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
877 	if (!dev->interrupt_out_urb)
878 		goto error;
879 	dev->interrupt_in_interval = interrupt_in_interval ? interrupt_in_interval : dev->interrupt_in_endpoint->bInterval;
880 	dev->interrupt_out_interval = interrupt_out_interval ? interrupt_out_interval : dev->interrupt_out_endpoint->bInterval;
881 
882 	get_version_reply = kmalloc(sizeof(*get_version_reply), GFP_KERNEL);
883 
884 	if (!get_version_reply) {
885 		retval = -ENOMEM;
886 		goto error;
887 	}
888 
889 	/* get the firmware version and log it */
890 	result = usb_control_msg (udev,
891 				  usb_rcvctrlpipe(udev, 0),
892 				  LEGO_USB_TOWER_REQUEST_GET_VERSION,
893 				  USB_TYPE_VENDOR | USB_DIR_IN | USB_RECIP_DEVICE,
894 				  0,
895 				  0,
896 				  get_version_reply,
897 				  sizeof(*get_version_reply),
898 				  1000);
899 	if (result < 0) {
900 		dev_err(idev, "LEGO USB Tower get version control request failed\n");
901 		retval = result;
902 		goto error;
903 	}
904 	dev_info(&interface->dev,
905 		 "LEGO USB Tower firmware version is %d.%d build %d\n",
906 		 get_version_reply->major,
907 		 get_version_reply->minor,
908 		 le16_to_cpu(get_version_reply->build_no));
909 
910 	/* we can register the device now, as it is ready */
911 	usb_set_intfdata (interface, dev);
912 
913 	retval = usb_register_dev (interface, &tower_class);
914 
915 	if (retval) {
916 		/* something prevented us from registering this driver */
917 		dev_err(idev, "Not able to get a minor for this device.\n");
918 		usb_set_intfdata (interface, NULL);
919 		goto error;
920 	}
921 	dev->minor = interface->minor;
922 
923 	/* let the user know what node this device is now attached to */
924 	dev_info(&interface->dev, "LEGO USB Tower #%d now attached to major "
925 		 "%d minor %d\n", (dev->minor - LEGO_USB_TOWER_MINOR_BASE),
926 		 USB_MAJOR, dev->minor);
927 
928 exit:
929 	kfree(get_version_reply);
930 	return retval;
931 
932 error:
933 	kfree(get_version_reply);
934 	tower_delete(dev);
935 	return retval;
936 }
937 
938 
939 /**
940  *	tower_disconnect
941  *
942  *	Called by the usb core when the device is removed from the system.
943  */
944 static void tower_disconnect (struct usb_interface *interface)
945 {
946 	struct lego_usb_tower *dev;
947 	int minor;
948 
949 	dev = usb_get_intfdata (interface);
950 	mutex_lock(&open_disc_mutex);
951 	usb_set_intfdata (interface, NULL);
952 
953 	minor = dev->minor;
954 
955 	/* give back our minor */
956 	usb_deregister_dev (interface, &tower_class);
957 
958 	mutex_lock(&dev->lock);
959 	mutex_unlock(&open_disc_mutex);
960 
961 	/* if the device is not opened, then we clean up right now */
962 	if (!dev->open_count) {
963 		mutex_unlock(&dev->lock);
964 		tower_delete (dev);
965 	} else {
966 		dev->udev = NULL;
967 		/* wake up pollers */
968 		wake_up_interruptible_all(&dev->read_wait);
969 		wake_up_interruptible_all(&dev->write_wait);
970 		mutex_unlock(&dev->lock);
971 	}
972 
973 	dev_info(&interface->dev, "LEGO USB Tower #%d now disconnected\n",
974 		 (minor - LEGO_USB_TOWER_MINOR_BASE));
975 }
976 
977 module_usb_driver(tower_driver);
978 
979 MODULE_AUTHOR(DRIVER_AUTHOR);
980 MODULE_DESCRIPTION(DRIVER_DESC);
981 #ifdef MODULE_LICENSE
982 MODULE_LICENSE("GPL");
983 #endif
984