xref: /linux/drivers/usb/misc/ldusb.c (revision 20d0021394c1b070bf04b22c5bc8fdb437edd4c5)
1 /**
2  * Generic USB driver for report based interrupt in/out devices
3  * like LD Didactic's USB devices. LD Didactic's USB devices are
4  * HID devices which do not use HID report definitons (they use
5  * raw interrupt in and our reports only for communication).
6  *
7  * This driver uses a ring buffer for time critical reading of
8  * interrupt in reports and provides read and write methods for
9  * raw interrupt reports (similar to the Windows HID driver).
10  * Devices based on the book USB COMPLETE by Jan Axelson may need
11  * such a compatibility to the Windows HID driver.
12  *
13  * Copyright (C) 2005 Michael Hund <mhund@ld-didactic.de>
14  *
15  *	This program is free software; you can redistribute it and/or
16  *	modify it under the terms of the GNU General Public License as
17  *	published by the Free Software Foundation; either version 2 of
18  *	the License, or (at your option) any later version.
19  *
20  * Derived from Lego USB Tower driver
21  * Copyright (C) 2003 David Glance <advidgsf@sourceforge.net>
22  *		 2001-2004 Juergen Stuber <starblue@users.sourceforge.net>
23  *
24  * V0.1  (mh) Initial version
25  * V0.11 (mh) Added raw support for HID 1.0 devices (no interrupt out endpoint)
26  */
27 
28 #include <linux/config.h>
29 #include <linux/kernel.h>
30 #include <linux/errno.h>
31 #include <linux/init.h>
32 #include <linux/slab.h>
33 #include <linux/module.h>
34 
35 #include <asm/uaccess.h>
36 #include <linux/input.h>
37 #include <linux/usb.h>
38 #include <linux/poll.h>
39 
40 /* Define these values to match your devices */
41 #define USB_VENDOR_ID_LD		0x0f11	/* USB Vendor ID of LD Didactic GmbH */
42 #define USB_DEVICE_ID_CASSY		0x1000	/* USB Product ID for all CASSY-S modules */
43 #define USB_DEVICE_ID_POCKETCASSY	0x1010	/* USB Product ID for Pocket-CASSY */
44 #define USB_DEVICE_ID_MOBILECASSY	0x1020	/* USB Product ID for Mobile-CASSY */
45 #define USB_DEVICE_ID_JWM		0x1080	/* USB Product ID for Joule and Wattmeter */
46 #define USB_DEVICE_ID_DMMP		0x1081	/* USB Product ID for Digital Multimeter P (reserved) */
47 #define USB_DEVICE_ID_UMIP		0x1090	/* USB Product ID for UMI P */
48 #define USB_DEVICE_ID_VIDEOCOM		0x1200	/* USB Product ID for VideoCom */
49 #define USB_DEVICE_ID_COM3LAB		0x2000	/* USB Product ID for COM3LAB */
50 #define USB_DEVICE_ID_TELEPORT		0x2010	/* USB Product ID for Terminal Adapter */
51 #define USB_DEVICE_ID_NETWORKANALYSER	0x2020	/* USB Product ID for Network Analyser */
52 #define USB_DEVICE_ID_POWERCONTROL	0x2030	/* USB Product ID for Controlling device for Power Electronics */
53 
54 #define USB_VENDOR_ID_VERNIER		0x08f7
55 #define USB_DEVICE_ID_VERNIER_LABPRO	0x0001
56 #define USB_DEVICE_ID_VERNIER_GOTEMP	0x0002
57 #define USB_DEVICE_ID_VERNIER_SKIP	0x0003
58 #define USB_DEVICE_ID_VERNIER_CYCLOPS	0x0004
59 
60 
61 #ifdef CONFIG_USB_DYNAMIC_MINORS
62 #define USB_LD_MINOR_BASE	0
63 #else
64 #define USB_LD_MINOR_BASE	176
65 #endif
66 
67 /* table of devices that work with this driver */
68 static struct usb_device_id ld_usb_table [] = {
69 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_CASSY) },
70 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_POCKETCASSY) },
71 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_MOBILECASSY) },
72 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_JWM) },
73 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_DMMP) },
74 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_UMIP) },
75 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_VIDEOCOM) },
76 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_COM3LAB) },
77 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_TELEPORT) },
78 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_NETWORKANALYSER) },
79 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_POWERCONTROL) },
80 	{ USB_DEVICE(USB_VENDOR_ID_VERNIER, USB_DEVICE_ID_VERNIER_LABPRO) },
81 	{ USB_DEVICE(USB_VENDOR_ID_VERNIER, USB_DEVICE_ID_VERNIER_GOTEMP) },
82 	{ USB_DEVICE(USB_VENDOR_ID_VERNIER, USB_DEVICE_ID_VERNIER_SKIP) },
83 	{ USB_DEVICE(USB_VENDOR_ID_VERNIER, USB_DEVICE_ID_VERNIER_CYCLOPS) },
84 	{ }					/* Terminating entry */
85 };
86 MODULE_DEVICE_TABLE(usb, ld_usb_table);
87 MODULE_VERSION("V0.11");
88 MODULE_AUTHOR("Michael Hund <mhund@ld-didactic.de>");
89 MODULE_DESCRIPTION("LD USB Driver");
90 MODULE_LICENSE("GPL");
91 MODULE_SUPPORTED_DEVICE("LD USB Devices");
92 
93 #ifdef CONFIG_USB_DEBUG
94 	static int debug = 1;
95 #else
96 	static int debug = 0;
97 #endif
98 
99 /* Use our own dbg macro */
100 #define dbg_info(dev, format, arg...) do { if (debug) dev_info(dev , format , ## arg); } while (0)
101 
102 /* Module parameters */
103 module_param(debug, int, S_IRUGO | S_IWUSR);
104 MODULE_PARM_DESC(debug, "Debug enabled or not");
105 
106 /* All interrupt in transfers are collected in a ring buffer to
107  * avoid racing conditions and get better performance of the driver.
108  */
109 static int ring_buffer_size = 128;
110 module_param(ring_buffer_size, int, 0);
111 MODULE_PARM_DESC(ring_buffer_size, "Read ring buffer size in reports");
112 
113 /* The write_buffer can contain more than one interrupt out transfer.
114  */
115 static int write_buffer_size = 10;
116 module_param(write_buffer_size, int, 0);
117 MODULE_PARM_DESC(write_buffer_size, "Write buffer size in reports");
118 
119 /* As of kernel version 2.6.4 ehci-hcd uses an
120  * "only one interrupt transfer per frame" shortcut
121  * to simplify the scheduling of periodic transfers.
122  * This conflicts with our standard 1ms intervals for in and out URBs.
123  * We use default intervals of 2ms for in and 2ms for out transfers,
124  * which should be fast enough.
125  * Increase the interval to allow more devices that do interrupt transfers,
126  * or set to 1 to use the standard interval from the endpoint descriptors.
127  */
128 static int min_interrupt_in_interval = 2;
129 module_param(min_interrupt_in_interval, int, 0);
130 MODULE_PARM_DESC(min_interrupt_in_interval, "Minimum interrupt in interval in ms");
131 
132 static int min_interrupt_out_interval = 2;
133 module_param(min_interrupt_out_interval, int, 0);
134 MODULE_PARM_DESC(min_interrupt_out_interval, "Minimum interrupt out interval in ms");
135 
136 /* Structure to hold all of our device specific stuff */
137 struct ld_usb {
138 	struct semaphore	sem;		/* locks this structure */
139 	struct usb_interface*	intf;		/* save off the usb interface pointer */
140 
141 	int			open_count;	/* number of times this port has been opened */
142 
143 	char*			ring_buffer;
144 	unsigned int		ring_head;
145 	unsigned int		ring_tail;
146 
147 	wait_queue_head_t	read_wait;
148 	wait_queue_head_t	write_wait;
149 
150 	char*			interrupt_in_buffer;
151 	struct usb_endpoint_descriptor* interrupt_in_endpoint;
152 	struct urb*		interrupt_in_urb;
153 	int			interrupt_in_interval;
154 	size_t			interrupt_in_endpoint_size;
155 	int			interrupt_in_running;
156 	int			interrupt_in_done;
157 
158 	char*			interrupt_out_buffer;
159 	struct usb_endpoint_descriptor* interrupt_out_endpoint;
160 	struct urb*		interrupt_out_urb;
161 	int			interrupt_out_interval;
162 	size_t			interrupt_out_endpoint_size;
163 	int			interrupt_out_busy;
164 };
165 
166 /* prevent races between open() and disconnect() */
167 static DECLARE_MUTEX(disconnect_sem);
168 
169 static struct usb_driver ld_usb_driver;
170 
171 /**
172  *	ld_usb_abort_transfers
173  *      aborts transfers and frees associated data structures
174  */
175 static void ld_usb_abort_transfers(struct ld_usb *dev)
176 {
177 	/* shutdown transfer */
178 	if (dev->interrupt_in_running) {
179 		dev->interrupt_in_running = 0;
180 		if (dev->intf)
181 			usb_kill_urb(dev->interrupt_in_urb);
182 	}
183 	if (dev->interrupt_out_busy)
184 		if (dev->intf)
185 			usb_kill_urb(dev->interrupt_out_urb);
186 }
187 
188 /**
189  *	ld_usb_delete
190  */
191 static void ld_usb_delete(struct ld_usb *dev)
192 {
193 	ld_usb_abort_transfers(dev);
194 
195 	/* free data structures */
196 	usb_free_urb(dev->interrupt_in_urb);
197 	usb_free_urb(dev->interrupt_out_urb);
198 	kfree(dev->ring_buffer);
199 	kfree(dev->interrupt_in_buffer);
200 	kfree(dev->interrupt_out_buffer);
201 	kfree(dev);
202 }
203 
204 /**
205  *	ld_usb_interrupt_in_callback
206  */
207 static void ld_usb_interrupt_in_callback(struct urb *urb, struct pt_regs *regs)
208 {
209 	struct ld_usb *dev = urb->context;
210 	size_t *actual_buffer;
211 	unsigned int next_ring_head;
212 	int retval;
213 
214 	if (urb->status) {
215 		if (urb->status == -ENOENT ||
216 		    urb->status == -ECONNRESET ||
217 		    urb->status == -ESHUTDOWN) {
218 			goto exit;
219 		} else {
220 			dbg_info(&dev->intf->dev, "%s: nonzero status received: %d\n",
221 				 __FUNCTION__, urb->status);
222 			goto resubmit; /* maybe we can recover */
223 		}
224 	}
225 
226 	if (urb->actual_length > 0) {
227 		next_ring_head = (dev->ring_head+1) % ring_buffer_size;
228 		if (next_ring_head != dev->ring_tail) {
229 			actual_buffer = (size_t*)(dev->ring_buffer + dev->ring_head*(sizeof(size_t)+dev->interrupt_in_endpoint_size));
230 			/* actual_buffer gets urb->actual_length + interrupt_in_buffer */
231 			*actual_buffer = urb->actual_length;
232 			memcpy(actual_buffer+1, dev->interrupt_in_buffer, urb->actual_length);
233 			dev->ring_head = next_ring_head;
234 			dbg_info(&dev->intf->dev, "%s: received %d bytes\n",
235 				 __FUNCTION__, urb->actual_length);
236 		} else
237 			dev_warn(&dev->intf->dev,
238 				 "Ring buffer overflow, %d bytes dropped\n",
239 				 urb->actual_length);
240 	}
241 
242 resubmit:
243 	/* resubmit if we're still running */
244 	if (dev->interrupt_in_running && dev->intf) {
245 		retval = usb_submit_urb(dev->interrupt_in_urb, GFP_ATOMIC);
246 		if (retval)
247 			dev_err(&dev->intf->dev,
248 				"usb_submit_urb failed (%d)\n", retval);
249 	}
250 
251 exit:
252 	dev->interrupt_in_done = 1;
253 	wake_up_interruptible(&dev->read_wait);
254 }
255 
256 /**
257  *	ld_usb_interrupt_out_callback
258  */
259 static void ld_usb_interrupt_out_callback(struct urb *urb, struct pt_regs *regs)
260 {
261 	struct ld_usb *dev = urb->context;
262 
263 	/* sync/async unlink faults aren't errors */
264 	if (urb->status && !(urb->status == -ENOENT ||
265 			     urb->status == -ECONNRESET ||
266 			     urb->status == -ESHUTDOWN))
267 		dbg_info(&dev->intf->dev,
268 			 "%s - nonzero write interrupt status received: %d\n",
269 			 __FUNCTION__, urb->status);
270 
271 	dev->interrupt_out_busy = 0;
272 	wake_up_interruptible(&dev->write_wait);
273 }
274 
275 /**
276  *	ld_usb_open
277  */
278 static int ld_usb_open(struct inode *inode, struct file *file)
279 {
280 	struct ld_usb *dev;
281 	int subminor;
282 	int retval = 0;
283 	struct usb_interface *interface;
284 
285 	nonseekable_open(inode, file);
286 	subminor = iminor(inode);
287 
288 	down(&disconnect_sem);
289 
290 	interface = usb_find_interface(&ld_usb_driver, subminor);
291 
292 	if (!interface) {
293 		err("%s - error, can't find device for minor %d\n",
294 		     __FUNCTION__, subminor);
295 		retval = -ENODEV;
296 		goto unlock_disconnect_exit;
297 	}
298 
299 	dev = usb_get_intfdata(interface);
300 
301 	if (!dev) {
302 		retval = -ENODEV;
303 		goto unlock_disconnect_exit;
304 	}
305 
306 	/* lock this device */
307 	if (down_interruptible(&dev->sem)) {
308 		retval = -ERESTARTSYS;
309 		goto unlock_disconnect_exit;
310 	}
311 
312 	/* allow opening only once */
313 	if (dev->open_count) {
314 		retval = -EBUSY;
315 		goto unlock_exit;
316 	}
317 	dev->open_count = 1;
318 
319 	/* initialize in direction */
320 	dev->ring_head = 0;
321 	dev->ring_tail = 0;
322 	usb_fill_int_urb(dev->interrupt_in_urb,
323 			 interface_to_usbdev(interface),
324 			 usb_rcvintpipe(interface_to_usbdev(interface),
325 					dev->interrupt_in_endpoint->bEndpointAddress),
326 			 dev->interrupt_in_buffer,
327 			 dev->interrupt_in_endpoint_size,
328 			 ld_usb_interrupt_in_callback,
329 			 dev,
330 			 dev->interrupt_in_interval);
331 
332 	dev->interrupt_in_running = 1;
333 	dev->interrupt_in_done = 0;
334 
335 	retval = usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
336 	if (retval) {
337 		dev_err(&interface->dev, "Couldn't submit interrupt_in_urb %d\n", retval);
338 		dev->interrupt_in_running = 0;
339 		dev->open_count = 0;
340 		goto unlock_exit;
341 	}
342 
343 	/* save device in the file's private structure */
344 	file->private_data = dev;
345 
346 unlock_exit:
347 	up(&dev->sem);
348 
349 unlock_disconnect_exit:
350 	up(&disconnect_sem);
351 
352 	return retval;
353 }
354 
355 /**
356  *	ld_usb_release
357  */
358 static int ld_usb_release(struct inode *inode, struct file *file)
359 {
360 	struct ld_usb *dev;
361 	int retval = 0;
362 
363 	dev = file->private_data;
364 
365 	if (dev == NULL) {
366 		retval = -ENODEV;
367 		goto exit;
368 	}
369 
370 	if (down_interruptible(&dev->sem)) {
371 		retval = -ERESTARTSYS;
372 		goto exit;
373 	}
374 
375 	if (dev->open_count != 1) {
376 		retval = -ENODEV;
377 		goto unlock_exit;
378 	}
379 	if (dev->intf == NULL) {
380 		/* the device was unplugged before the file was released */
381 		up(&dev->sem);
382 		/* unlock here as ld_usb_delete frees dev */
383 		ld_usb_delete(dev);
384 		goto exit;
385 	}
386 
387 	/* wait until write transfer is finished */
388 	if (dev->interrupt_out_busy)
389 		wait_event_interruptible_timeout(dev->write_wait, !dev->interrupt_out_busy, 2 * HZ);
390 	ld_usb_abort_transfers(dev);
391 	dev->open_count = 0;
392 
393 unlock_exit:
394 	up(&dev->sem);
395 
396 exit:
397 	return retval;
398 }
399 
400 /**
401  *	ld_usb_poll
402  */
403 static unsigned int ld_usb_poll(struct file *file, poll_table *wait)
404 {
405 	struct ld_usb *dev;
406 	unsigned int mask = 0;
407 
408 	dev = file->private_data;
409 
410 	poll_wait(file, &dev->read_wait, wait);
411 	poll_wait(file, &dev->write_wait, wait);
412 
413 	if (dev->ring_head != dev->ring_tail)
414 		mask |= POLLIN | POLLRDNORM;
415 	if (!dev->interrupt_out_busy)
416 		mask |= POLLOUT | POLLWRNORM;
417 
418 	return mask;
419 }
420 
421 /**
422  *	ld_usb_read
423  */
424 static ssize_t ld_usb_read(struct file *file, char __user *buffer, size_t count,
425 			   loff_t *ppos)
426 {
427 	struct ld_usb *dev;
428 	size_t *actual_buffer;
429 	size_t bytes_to_read;
430 	int retval = 0;
431 
432 	dev = file->private_data;
433 
434 	/* verify that we actually have some data to read */
435 	if (count == 0)
436 		goto exit;
437 
438 	/* lock this object */
439 	if (down_interruptible(&dev->sem)) {
440 		retval = -ERESTARTSYS;
441 		goto exit;
442 	}
443 
444 	/* verify that the device wasn't unplugged */
445 	if (dev->intf == NULL) {
446 		retval = -ENODEV;
447 		err("No device or device unplugged %d\n", retval);
448 		goto unlock_exit;
449 	}
450 
451 	/* wait for data */
452 	if (dev->ring_head == dev->ring_tail) {
453 		if (file->f_flags & O_NONBLOCK) {
454 			retval = -EAGAIN;
455 			goto unlock_exit;
456 		}
457 		retval = wait_event_interruptible(dev->read_wait, dev->interrupt_in_done);
458 		if (retval < 0)
459 			goto unlock_exit;
460 	}
461 
462 	/* actual_buffer contains actual_length + interrupt_in_buffer */
463 	actual_buffer = (size_t*)(dev->ring_buffer + dev->ring_tail*(sizeof(size_t)+dev->interrupt_in_endpoint_size));
464 	bytes_to_read = min(count, *actual_buffer);
465 	if (bytes_to_read < *actual_buffer)
466 		dev_warn(&dev->intf->dev, "Read buffer overflow, %d bytes dropped\n",
467 			 *actual_buffer-bytes_to_read);
468 
469 	/* copy one interrupt_in_buffer from ring_buffer into userspace */
470 	if (copy_to_user(buffer, actual_buffer+1, bytes_to_read)) {
471 		retval = -EFAULT;
472 		goto unlock_exit;
473 	}
474 	dev->ring_tail = (dev->ring_tail+1) % ring_buffer_size;
475 
476 	retval = bytes_to_read;
477 
478 unlock_exit:
479 	/* unlock the device */
480 	up(&dev->sem);
481 
482 exit:
483 	return retval;
484 }
485 
486 /**
487  *	ld_usb_write
488  */
489 static ssize_t ld_usb_write(struct file *file, const char __user *buffer,
490 			    size_t count, loff_t *ppos)
491 {
492 	struct ld_usb *dev;
493 	size_t bytes_to_write;
494 	int retval = 0;
495 
496 	dev = file->private_data;
497 
498 	/* verify that we actually have some data to write */
499 	if (count == 0)
500 		goto exit;
501 
502 	/* lock this object */
503 	if (down_interruptible(&dev->sem)) {
504 		retval = -ERESTARTSYS;
505 		goto exit;
506 	}
507 
508 	/* verify that the device wasn't unplugged */
509 	if (dev->intf == NULL) {
510 		retval = -ENODEV;
511 		err("No device or device unplugged %d\n", retval);
512 		goto unlock_exit;
513 	}
514 
515 	/* wait until previous transfer is finished */
516 	if (dev->interrupt_out_busy) {
517 		if (file->f_flags & O_NONBLOCK) {
518 			retval = -EAGAIN;
519 			goto unlock_exit;
520 		}
521 		retval = wait_event_interruptible(dev->write_wait, !dev->interrupt_out_busy);
522 		if (retval < 0) {
523 			goto unlock_exit;
524 		}
525 	}
526 
527 	/* write the data into interrupt_out_buffer from userspace */
528 	bytes_to_write = min(count, write_buffer_size*dev->interrupt_out_endpoint_size);
529 	if (bytes_to_write < count)
530 		dev_warn(&dev->intf->dev, "Write buffer overflow, %d bytes dropped\n",count-bytes_to_write);
531 	dbg_info(&dev->intf->dev, "%s: count = %d, bytes_to_write = %d\n", __FUNCTION__, count, bytes_to_write);
532 
533 	if (copy_from_user(dev->interrupt_out_buffer, buffer, bytes_to_write)) {
534 		retval = -EFAULT;
535 		goto unlock_exit;
536 	}
537 
538 	if (dev->interrupt_out_endpoint == NULL) {
539 		/* try HID_REQ_SET_REPORT=9 on control_endpoint instead of interrupt_out_endpoint */
540 		retval = usb_control_msg(interface_to_usbdev(dev->intf),
541 					 usb_sndctrlpipe(interface_to_usbdev(dev->intf), 0),
542 					 9,
543 					 USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_OUT,
544 					 1 << 8, 0,
545 					 dev->interrupt_out_buffer,
546 					 bytes_to_write,
547 					 USB_CTRL_SET_TIMEOUT * HZ);
548 		if (retval < 0)
549 			err("Couldn't submit HID_REQ_SET_REPORT %d\n", retval);
550 		goto unlock_exit;
551 	}
552 
553 	/* send off the urb */
554 	usb_fill_int_urb(dev->interrupt_out_urb,
555 			 interface_to_usbdev(dev->intf),
556 			 usb_sndintpipe(interface_to_usbdev(dev->intf),
557 					dev->interrupt_out_endpoint->bEndpointAddress),
558 			 dev->interrupt_out_buffer,
559 			 bytes_to_write,
560 			 ld_usb_interrupt_out_callback,
561 			 dev,
562 			 dev->interrupt_out_interval);
563 
564 	dev->interrupt_out_busy = 1;
565 	wmb();
566 
567 	retval = usb_submit_urb(dev->interrupt_out_urb, GFP_KERNEL);
568 	if (retval) {
569 		dev->interrupt_out_busy = 0;
570 		err("Couldn't submit interrupt_out_urb %d\n", retval);
571 		goto unlock_exit;
572 	}
573 	retval = bytes_to_write;
574 
575 unlock_exit:
576 	/* unlock the device */
577 	up(&dev->sem);
578 
579 exit:
580 	return retval;
581 }
582 
583 /* file operations needed when we register this driver */
584 static struct file_operations ld_usb_fops = {
585 	.owner =	THIS_MODULE,
586 	.read  =	ld_usb_read,
587 	.write =	ld_usb_write,
588 	.open =		ld_usb_open,
589 	.release =	ld_usb_release,
590 	.poll =		ld_usb_poll,
591 };
592 
593 /*
594  * usb class driver info in order to get a minor number from the usb core,
595  * and to have the device registered with devfs and the driver core
596  */
597 static struct usb_class_driver ld_usb_class = {
598 	.name =		"ldusb%d",
599 	.fops =		&ld_usb_fops,
600 	.minor_base =	USB_LD_MINOR_BASE,
601 };
602 
603 /**
604  *	ld_usb_probe
605  *
606  *	Called by the usb core when a new device is connected that it thinks
607  *	this driver might be interested in.
608  */
609 static int ld_usb_probe(struct usb_interface *intf, const struct usb_device_id *id)
610 {
611 	struct usb_device *udev = interface_to_usbdev(intf);
612 	struct ld_usb *dev = NULL;
613 	struct usb_host_interface *iface_desc;
614 	struct usb_endpoint_descriptor *endpoint;
615 	char *buffer;
616 	int i;
617 	int retval = -ENOMEM;
618 
619 	/* allocate memory for our device state and intialize it */
620 
621 	dev = kmalloc(sizeof(*dev), GFP_KERNEL);
622 	if (dev == NULL) {
623 		dev_err(&intf->dev, "Out of memory\n");
624 		goto exit;
625 	}
626 	memset(dev, 0x00, sizeof(*dev));
627 	init_MUTEX(&dev->sem);
628 	dev->intf = intf;
629 	init_waitqueue_head(&dev->read_wait);
630 	init_waitqueue_head(&dev->write_wait);
631 
632 	/* workaround for early firmware versions on fast computers */
633 	if ((le16_to_cpu(udev->descriptor.idVendor) == USB_VENDOR_ID_LD) &&
634 	    ((le16_to_cpu(udev->descriptor.idProduct) == USB_DEVICE_ID_CASSY) ||
635 	     (le16_to_cpu(udev->descriptor.idProduct) == USB_DEVICE_ID_COM3LAB)) &&
636 	    (le16_to_cpu(udev->descriptor.bcdDevice) <= 0x103)) {
637 		buffer = kmalloc(256, GFP_KERNEL);
638 		/* usb_string makes SETUP+STALL to leave always ControlReadLoop */
639 		usb_string(udev, 255, buffer, 256);
640 		kfree(buffer);
641 	}
642 
643 	iface_desc = intf->cur_altsetting;
644 
645 	/* set up the endpoint information */
646 	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
647 		endpoint = &iface_desc->endpoint[i].desc;
648 
649 		if (((endpoint->bEndpointAddress & USB_ENDPOINT_DIR_MASK) == USB_DIR_IN) &&
650 		    ((endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) == USB_ENDPOINT_XFER_INT)) {
651 			dev->interrupt_in_endpoint = endpoint;
652 		}
653 
654 		if (((endpoint->bEndpointAddress & USB_ENDPOINT_DIR_MASK) == USB_DIR_OUT) &&
655 		    ((endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) == USB_ENDPOINT_XFER_INT)) {
656 			dev->interrupt_out_endpoint = endpoint;
657 		}
658 	}
659 	if (dev->interrupt_in_endpoint == NULL) {
660 		dev_err(&intf->dev, "Interrupt in endpoint not found\n");
661 		goto error;
662 	}
663 	if (dev->interrupt_out_endpoint == NULL)
664 		dev_warn(&intf->dev, "Interrupt out endpoint not found (using control endpoint instead)\n");
665 
666 	dev->interrupt_in_endpoint_size = le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize);
667 	dev->ring_buffer = kmalloc(ring_buffer_size*(sizeof(size_t)+dev->interrupt_in_endpoint_size), GFP_KERNEL);
668 	if (!dev->ring_buffer) {
669 		dev_err(&intf->dev, "Couldn't allocate ring_buffer\n");
670 		goto error;
671 	}
672 	dev->interrupt_in_buffer = kmalloc(dev->interrupt_in_endpoint_size, GFP_KERNEL);
673 	if (!dev->interrupt_in_buffer) {
674 		dev_err(&intf->dev, "Couldn't allocate interrupt_in_buffer\n");
675 		goto error;
676 	}
677 	dev->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
678 	if (!dev->interrupt_in_urb) {
679 		dev_err(&intf->dev, "Couldn't allocate interrupt_in_urb\n");
680 		goto error;
681 	}
682 	dev->interrupt_out_endpoint_size = dev->interrupt_out_endpoint ? le16_to_cpu(dev->interrupt_out_endpoint->wMaxPacketSize) :
683 									 udev->descriptor.bMaxPacketSize0;
684 	dev->interrupt_out_buffer = kmalloc(write_buffer_size*dev->interrupt_out_endpoint_size, GFP_KERNEL);
685 	if (!dev->interrupt_out_buffer) {
686 		dev_err(&intf->dev, "Couldn't allocate interrupt_out_buffer\n");
687 		goto error;
688 	}
689 	dev->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
690 	if (!dev->interrupt_out_urb) {
691 		dev_err(&intf->dev, "Couldn't allocate interrupt_out_urb\n");
692 		goto error;
693 	}
694 	dev->interrupt_in_interval = min_interrupt_in_interval > dev->interrupt_in_endpoint->bInterval ? min_interrupt_in_interval : dev->interrupt_in_endpoint->bInterval;
695 	if (dev->interrupt_out_endpoint)
696 		dev->interrupt_out_interval = min_interrupt_out_interval > dev->interrupt_out_endpoint->bInterval ? min_interrupt_out_interval : dev->interrupt_out_endpoint->bInterval;
697 
698 	/* we can register the device now, as it is ready */
699 	usb_set_intfdata(intf, dev);
700 
701 	retval = usb_register_dev(intf, &ld_usb_class);
702 	if (retval) {
703 		/* something prevented us from registering this driver */
704 		dev_err(&intf->dev, "Not able to get a minor for this device.\n");
705 		usb_set_intfdata(intf, NULL);
706 		goto error;
707 	}
708 
709 	/* let the user know what node this device is now attached to */
710 	dev_info(&intf->dev, "LD USB Device #%d now attached to major %d minor %d\n",
711 		(intf->minor - USB_LD_MINOR_BASE), USB_MAJOR, intf->minor);
712 
713 exit:
714 	return retval;
715 
716 error:
717 	ld_usb_delete(dev);
718 
719 	return retval;
720 }
721 
722 /**
723  *	ld_usb_disconnect
724  *
725  *	Called by the usb core when the device is removed from the system.
726  */
727 static void ld_usb_disconnect(struct usb_interface *intf)
728 {
729 	struct ld_usb *dev;
730 	int minor;
731 
732 	down(&disconnect_sem);
733 
734 	dev = usb_get_intfdata(intf);
735 	usb_set_intfdata(intf, NULL);
736 
737 	down(&dev->sem);
738 
739 	minor = intf->minor;
740 
741 	/* give back our minor */
742 	usb_deregister_dev(intf, &ld_usb_class);
743 
744 	/* if the device is not opened, then we clean up right now */
745 	if (!dev->open_count) {
746 		up(&dev->sem);
747 		ld_usb_delete(dev);
748 	} else {
749 		dev->intf = NULL;
750 		up(&dev->sem);
751 	}
752 
753 	up(&disconnect_sem);
754 
755 	dev_info(&intf->dev, "LD USB Device #%d now disconnected\n",
756 		 (minor - USB_LD_MINOR_BASE));
757 }
758 
759 /* usb specific object needed to register this driver with the usb subsystem */
760 static struct usb_driver ld_usb_driver = {
761 	.owner =	THIS_MODULE,
762 	.name =		"ldusb",
763 	.probe =	ld_usb_probe,
764 	.disconnect =	ld_usb_disconnect,
765 	.id_table =	ld_usb_table,
766 };
767 
768 /**
769  *	ld_usb_init
770  */
771 static int __init ld_usb_init(void)
772 {
773 	int retval;
774 
775 	/* register this driver with the USB subsystem */
776 	retval = usb_register(&ld_usb_driver);
777 	if (retval)
778 		err("usb_register failed for the "__FILE__" driver. Error number %d\n", retval);
779 
780 	return retval;
781 }
782 
783 /**
784  *	ld_usb_exit
785  */
786 static void __exit ld_usb_exit(void)
787 {
788 	/* deregister this driver with the USB subsystem */
789 	usb_deregister(&ld_usb_driver);
790 }
791 
792 module_init(ld_usb_init);
793 module_exit(ld_usb_exit);
794 
795