xref: /openbmc/linux/drivers/usb/misc/ldusb.c (revision 87c2ce3b)
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  * V0.12 (mh) Added kmalloc check for string buffer
27  */
28 
29 #include <linux/config.h>
30 #include <linux/kernel.h>
31 #include <linux/errno.h>
32 #include <linux/init.h>
33 #include <linux/slab.h>
34 #include <linux/module.h>
35 
36 #include <asm/uaccess.h>
37 #include <linux/input.h>
38 #include <linux/usb.h>
39 #include <linux/poll.h>
40 
41 /* Define these values to match your devices */
42 #define USB_VENDOR_ID_LD		0x0f11	/* USB Vendor ID of LD Didactic GmbH */
43 #define USB_DEVICE_ID_CASSY		0x1000	/* USB Product ID for all CASSY-S modules */
44 #define USB_DEVICE_ID_POCKETCASSY	0x1010	/* USB Product ID for Pocket-CASSY */
45 #define USB_DEVICE_ID_MOBILECASSY	0x1020	/* USB Product ID for Mobile-CASSY */
46 #define USB_DEVICE_ID_JWM		0x1080	/* USB Product ID for Joule and Wattmeter */
47 #define USB_DEVICE_ID_DMMP		0x1081	/* USB Product ID for Digital Multimeter P (reserved) */
48 #define USB_DEVICE_ID_UMIP		0x1090	/* USB Product ID for UMI P */
49 #define USB_DEVICE_ID_VIDEOCOM		0x1200	/* USB Product ID for VideoCom */
50 #define USB_DEVICE_ID_COM3LAB		0x2000	/* USB Product ID for COM3LAB */
51 #define USB_DEVICE_ID_TELEPORT		0x2010	/* USB Product ID for Terminal Adapter */
52 #define USB_DEVICE_ID_NETWORKANALYSER	0x2020	/* USB Product ID for Network Analyser */
53 #define USB_DEVICE_ID_POWERCONTROL	0x2030	/* USB Product ID for Controlling device for Power Electronics */
54 
55 #define USB_VENDOR_ID_VERNIER		0x08f7
56 #define USB_DEVICE_ID_VERNIER_LABPRO	0x0001
57 #define USB_DEVICE_ID_VERNIER_GOTEMP	0x0002
58 #define USB_DEVICE_ID_VERNIER_SKIP	0x0003
59 #define USB_DEVICE_ID_VERNIER_CYCLOPS	0x0004
60 
61 
62 #ifdef CONFIG_USB_DYNAMIC_MINORS
63 #define USB_LD_MINOR_BASE	0
64 #else
65 #define USB_LD_MINOR_BASE	176
66 #endif
67 
68 /* table of devices that work with this driver */
69 static struct usb_device_id ld_usb_table [] = {
70 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_CASSY) },
71 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_POCKETCASSY) },
72 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_MOBILECASSY) },
73 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_JWM) },
74 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_DMMP) },
75 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_UMIP) },
76 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_VIDEOCOM) },
77 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_COM3LAB) },
78 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_TELEPORT) },
79 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_NETWORKANALYSER) },
80 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_POWERCONTROL) },
81 	{ USB_DEVICE(USB_VENDOR_ID_VERNIER, USB_DEVICE_ID_VERNIER_LABPRO) },
82 	{ USB_DEVICE(USB_VENDOR_ID_VERNIER, USB_DEVICE_ID_VERNIER_GOTEMP) },
83 	{ USB_DEVICE(USB_VENDOR_ID_VERNIER, USB_DEVICE_ID_VERNIER_SKIP) },
84 	{ USB_DEVICE(USB_VENDOR_ID_VERNIER, USB_DEVICE_ID_VERNIER_CYCLOPS) },
85 	{ }					/* Terminating entry */
86 };
87 MODULE_DEVICE_TABLE(usb, ld_usb_table);
88 MODULE_VERSION("V0.12");
89 MODULE_AUTHOR("Michael Hund <mhund@ld-didactic.de>");
90 MODULE_DESCRIPTION("LD USB Driver");
91 MODULE_LICENSE("GPL");
92 MODULE_SUPPORTED_DEVICE("LD USB Devices");
93 
94 #ifdef CONFIG_USB_DEBUG
95 	static int debug = 1;
96 #else
97 	static int debug = 0;
98 #endif
99 
100 /* Use our own dbg macro */
101 #define dbg_info(dev, format, arg...) do { if (debug) dev_info(dev , format , ## arg); } while (0)
102 
103 /* Module parameters */
104 module_param(debug, int, S_IRUGO | S_IWUSR);
105 MODULE_PARM_DESC(debug, "Debug enabled or not");
106 
107 /* All interrupt in transfers are collected in a ring buffer to
108  * avoid racing conditions and get better performance of the driver.
109  */
110 static int ring_buffer_size = 128;
111 module_param(ring_buffer_size, int, 0);
112 MODULE_PARM_DESC(ring_buffer_size, "Read ring buffer size in reports");
113 
114 /* The write_buffer can contain more than one interrupt out transfer.
115  */
116 static int write_buffer_size = 10;
117 module_param(write_buffer_size, int, 0);
118 MODULE_PARM_DESC(write_buffer_size, "Write buffer size in reports");
119 
120 /* As of kernel version 2.6.4 ehci-hcd uses an
121  * "only one interrupt transfer per frame" shortcut
122  * to simplify the scheduling of periodic transfers.
123  * This conflicts with our standard 1ms intervals for in and out URBs.
124  * We use default intervals of 2ms for in and 2ms for out transfers,
125  * which should be fast enough.
126  * Increase the interval to allow more devices that do interrupt transfers,
127  * or set to 1 to use the standard interval from the endpoint descriptors.
128  */
129 static int min_interrupt_in_interval = 2;
130 module_param(min_interrupt_in_interval, int, 0);
131 MODULE_PARM_DESC(min_interrupt_in_interval, "Minimum interrupt in interval in ms");
132 
133 static int min_interrupt_out_interval = 2;
134 module_param(min_interrupt_out_interval, int, 0);
135 MODULE_PARM_DESC(min_interrupt_out_interval, "Minimum interrupt out interval in ms");
136 
137 /* Structure to hold all of our device specific stuff */
138 struct ld_usb {
139 	struct semaphore	sem;		/* locks this structure */
140 	struct usb_interface*	intf;		/* save off the usb interface pointer */
141 
142 	int			open_count;	/* number of times this port has been opened */
143 
144 	char*			ring_buffer;
145 	unsigned int		ring_head;
146 	unsigned int		ring_tail;
147 
148 	wait_queue_head_t	read_wait;
149 	wait_queue_head_t	write_wait;
150 
151 	char*			interrupt_in_buffer;
152 	struct usb_endpoint_descriptor* interrupt_in_endpoint;
153 	struct urb*		interrupt_in_urb;
154 	int			interrupt_in_interval;
155 	size_t			interrupt_in_endpoint_size;
156 	int			interrupt_in_running;
157 	int			interrupt_in_done;
158 
159 	char*			interrupt_out_buffer;
160 	struct usb_endpoint_descriptor* interrupt_out_endpoint;
161 	struct urb*		interrupt_out_urb;
162 	int			interrupt_out_interval;
163 	size_t			interrupt_out_endpoint_size;
164 	int			interrupt_out_busy;
165 };
166 
167 /* prevent races between open() and disconnect() */
168 static DECLARE_MUTEX(disconnect_sem);
169 
170 static struct usb_driver ld_usb_driver;
171 
172 /**
173  *	ld_usb_abort_transfers
174  *      aborts transfers and frees associated data structures
175  */
176 static void ld_usb_abort_transfers(struct ld_usb *dev)
177 {
178 	/* shutdown transfer */
179 	if (dev->interrupt_in_running) {
180 		dev->interrupt_in_running = 0;
181 		if (dev->intf)
182 			usb_kill_urb(dev->interrupt_in_urb);
183 	}
184 	if (dev->interrupt_out_busy)
185 		if (dev->intf)
186 			usb_kill_urb(dev->interrupt_out_urb);
187 }
188 
189 /**
190  *	ld_usb_delete
191  */
192 static void ld_usb_delete(struct ld_usb *dev)
193 {
194 	ld_usb_abort_transfers(dev);
195 
196 	/* free data structures */
197 	usb_free_urb(dev->interrupt_in_urb);
198 	usb_free_urb(dev->interrupt_out_urb);
199 	kfree(dev->ring_buffer);
200 	kfree(dev->interrupt_in_buffer);
201 	kfree(dev->interrupt_out_buffer);
202 	kfree(dev);
203 }
204 
205 /**
206  *	ld_usb_interrupt_in_callback
207  */
208 static void ld_usb_interrupt_in_callback(struct urb *urb, struct pt_regs *regs)
209 {
210 	struct ld_usb *dev = urb->context;
211 	size_t *actual_buffer;
212 	unsigned int next_ring_head;
213 	int retval;
214 
215 	if (urb->status) {
216 		if (urb->status == -ENOENT ||
217 		    urb->status == -ECONNRESET ||
218 		    urb->status == -ESHUTDOWN) {
219 			goto exit;
220 		} else {
221 			dbg_info(&dev->intf->dev, "%s: nonzero status received: %d\n",
222 				 __FUNCTION__, urb->status);
223 			goto resubmit; /* maybe we can recover */
224 		}
225 	}
226 
227 	if (urb->actual_length > 0) {
228 		next_ring_head = (dev->ring_head+1) % ring_buffer_size;
229 		if (next_ring_head != dev->ring_tail) {
230 			actual_buffer = (size_t*)(dev->ring_buffer + dev->ring_head*(sizeof(size_t)+dev->interrupt_in_endpoint_size));
231 			/* actual_buffer gets urb->actual_length + interrupt_in_buffer */
232 			*actual_buffer = urb->actual_length;
233 			memcpy(actual_buffer+1, dev->interrupt_in_buffer, urb->actual_length);
234 			dev->ring_head = next_ring_head;
235 			dbg_info(&dev->intf->dev, "%s: received %d bytes\n",
236 				 __FUNCTION__, urb->actual_length);
237 		} else
238 			dev_warn(&dev->intf->dev,
239 				 "Ring buffer overflow, %d bytes dropped\n",
240 				 urb->actual_length);
241 	}
242 
243 resubmit:
244 	/* resubmit if we're still running */
245 	if (dev->interrupt_in_running && dev->intf) {
246 		retval = usb_submit_urb(dev->interrupt_in_urb, GFP_ATOMIC);
247 		if (retval)
248 			dev_err(&dev->intf->dev,
249 				"usb_submit_urb failed (%d)\n", retval);
250 	}
251 
252 exit:
253 	dev->interrupt_in_done = 1;
254 	wake_up_interruptible(&dev->read_wait);
255 }
256 
257 /**
258  *	ld_usb_interrupt_out_callback
259  */
260 static void ld_usb_interrupt_out_callback(struct urb *urb, struct pt_regs *regs)
261 {
262 	struct ld_usb *dev = urb->context;
263 
264 	/* sync/async unlink faults aren't errors */
265 	if (urb->status && !(urb->status == -ENOENT ||
266 			     urb->status == -ECONNRESET ||
267 			     urb->status == -ESHUTDOWN))
268 		dbg_info(&dev->intf->dev,
269 			 "%s - nonzero write interrupt status received: %d\n",
270 			 __FUNCTION__, urb->status);
271 
272 	dev->interrupt_out_busy = 0;
273 	wake_up_interruptible(&dev->write_wait);
274 }
275 
276 /**
277  *	ld_usb_open
278  */
279 static int ld_usb_open(struct inode *inode, struct file *file)
280 {
281 	struct ld_usb *dev;
282 	int subminor;
283 	int retval = 0;
284 	struct usb_interface *interface;
285 
286 	nonseekable_open(inode, file);
287 	subminor = iminor(inode);
288 
289 	down(&disconnect_sem);
290 
291 	interface = usb_find_interface(&ld_usb_driver, subminor);
292 
293 	if (!interface) {
294 		err("%s - error, can't find device for minor %d\n",
295 		     __FUNCTION__, subminor);
296 		retval = -ENODEV;
297 		goto unlock_disconnect_exit;
298 	}
299 
300 	dev = usb_get_intfdata(interface);
301 
302 	if (!dev) {
303 		retval = -ENODEV;
304 		goto unlock_disconnect_exit;
305 	}
306 
307 	/* lock this device */
308 	if (down_interruptible(&dev->sem)) {
309 		retval = -ERESTARTSYS;
310 		goto unlock_disconnect_exit;
311 	}
312 
313 	/* allow opening only once */
314 	if (dev->open_count) {
315 		retval = -EBUSY;
316 		goto unlock_exit;
317 	}
318 	dev->open_count = 1;
319 
320 	/* initialize in direction */
321 	dev->ring_head = 0;
322 	dev->ring_tail = 0;
323 	usb_fill_int_urb(dev->interrupt_in_urb,
324 			 interface_to_usbdev(interface),
325 			 usb_rcvintpipe(interface_to_usbdev(interface),
326 					dev->interrupt_in_endpoint->bEndpointAddress),
327 			 dev->interrupt_in_buffer,
328 			 dev->interrupt_in_endpoint_size,
329 			 ld_usb_interrupt_in_callback,
330 			 dev,
331 			 dev->interrupt_in_interval);
332 
333 	dev->interrupt_in_running = 1;
334 	dev->interrupt_in_done = 0;
335 
336 	retval = usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
337 	if (retval) {
338 		dev_err(&interface->dev, "Couldn't submit interrupt_in_urb %d\n", retval);
339 		dev->interrupt_in_running = 0;
340 		dev->open_count = 0;
341 		goto unlock_exit;
342 	}
343 
344 	/* save device in the file's private structure */
345 	file->private_data = dev;
346 
347 unlock_exit:
348 	up(&dev->sem);
349 
350 unlock_disconnect_exit:
351 	up(&disconnect_sem);
352 
353 	return retval;
354 }
355 
356 /**
357  *	ld_usb_release
358  */
359 static int ld_usb_release(struct inode *inode, struct file *file)
360 {
361 	struct ld_usb *dev;
362 	int retval = 0;
363 
364 	dev = file->private_data;
365 
366 	if (dev == NULL) {
367 		retval = -ENODEV;
368 		goto exit;
369 	}
370 
371 	if (down_interruptible(&dev->sem)) {
372 		retval = -ERESTARTSYS;
373 		goto exit;
374 	}
375 
376 	if (dev->open_count != 1) {
377 		retval = -ENODEV;
378 		goto unlock_exit;
379 	}
380 	if (dev->intf == NULL) {
381 		/* the device was unplugged before the file was released */
382 		up(&dev->sem);
383 		/* unlock here as ld_usb_delete frees dev */
384 		ld_usb_delete(dev);
385 		goto exit;
386 	}
387 
388 	/* wait until write transfer is finished */
389 	if (dev->interrupt_out_busy)
390 		wait_event_interruptible_timeout(dev->write_wait, !dev->interrupt_out_busy, 2 * HZ);
391 	ld_usb_abort_transfers(dev);
392 	dev->open_count = 0;
393 
394 unlock_exit:
395 	up(&dev->sem);
396 
397 exit:
398 	return retval;
399 }
400 
401 /**
402  *	ld_usb_poll
403  */
404 static unsigned int ld_usb_poll(struct file *file, poll_table *wait)
405 {
406 	struct ld_usb *dev;
407 	unsigned int mask = 0;
408 
409 	dev = file->private_data;
410 
411 	poll_wait(file, &dev->read_wait, wait);
412 	poll_wait(file, &dev->write_wait, wait);
413 
414 	if (dev->ring_head != dev->ring_tail)
415 		mask |= POLLIN | POLLRDNORM;
416 	if (!dev->interrupt_out_busy)
417 		mask |= POLLOUT | POLLWRNORM;
418 
419 	return mask;
420 }
421 
422 /**
423  *	ld_usb_read
424  */
425 static ssize_t ld_usb_read(struct file *file, char __user *buffer, size_t count,
426 			   loff_t *ppos)
427 {
428 	struct ld_usb *dev;
429 	size_t *actual_buffer;
430 	size_t bytes_to_read;
431 	int retval = 0;
432 
433 	dev = file->private_data;
434 
435 	/* verify that we actually have some data to read */
436 	if (count == 0)
437 		goto exit;
438 
439 	/* lock this object */
440 	if (down_interruptible(&dev->sem)) {
441 		retval = -ERESTARTSYS;
442 		goto exit;
443 	}
444 
445 	/* verify that the device wasn't unplugged */
446 	if (dev->intf == NULL) {
447 		retval = -ENODEV;
448 		err("No device or device unplugged %d\n", retval);
449 		goto unlock_exit;
450 	}
451 
452 	/* wait for data */
453 	if (dev->ring_head == dev->ring_tail) {
454 		if (file->f_flags & O_NONBLOCK) {
455 			retval = -EAGAIN;
456 			goto unlock_exit;
457 		}
458 		retval = wait_event_interruptible(dev->read_wait, dev->interrupt_in_done);
459 		if (retval < 0)
460 			goto unlock_exit;
461 	}
462 
463 	/* actual_buffer contains actual_length + interrupt_in_buffer */
464 	actual_buffer = (size_t*)(dev->ring_buffer + dev->ring_tail*(sizeof(size_t)+dev->interrupt_in_endpoint_size));
465 	bytes_to_read = min(count, *actual_buffer);
466 	if (bytes_to_read < *actual_buffer)
467 		dev_warn(&dev->intf->dev, "Read buffer overflow, %zd bytes dropped\n",
468 			 *actual_buffer-bytes_to_read);
469 
470 	/* copy one interrupt_in_buffer from ring_buffer into userspace */
471 	if (copy_to_user(buffer, actual_buffer+1, bytes_to_read)) {
472 		retval = -EFAULT;
473 		goto unlock_exit;
474 	}
475 	dev->ring_tail = (dev->ring_tail+1) % ring_buffer_size;
476 
477 	retval = bytes_to_read;
478 
479 unlock_exit:
480 	/* unlock the device */
481 	up(&dev->sem);
482 
483 exit:
484 	return retval;
485 }
486 
487 /**
488  *	ld_usb_write
489  */
490 static ssize_t ld_usb_write(struct file *file, const char __user *buffer,
491 			    size_t count, loff_t *ppos)
492 {
493 	struct ld_usb *dev;
494 	size_t bytes_to_write;
495 	int retval = 0;
496 
497 	dev = file->private_data;
498 
499 	/* verify that we actually have some data to write */
500 	if (count == 0)
501 		goto exit;
502 
503 	/* lock this object */
504 	if (down_interruptible(&dev->sem)) {
505 		retval = -ERESTARTSYS;
506 		goto exit;
507 	}
508 
509 	/* verify that the device wasn't unplugged */
510 	if (dev->intf == NULL) {
511 		retval = -ENODEV;
512 		err("No device or device unplugged %d\n", retval);
513 		goto unlock_exit;
514 	}
515 
516 	/* wait until previous transfer is finished */
517 	if (dev->interrupt_out_busy) {
518 		if (file->f_flags & O_NONBLOCK) {
519 			retval = -EAGAIN;
520 			goto unlock_exit;
521 		}
522 		retval = wait_event_interruptible(dev->write_wait, !dev->interrupt_out_busy);
523 		if (retval < 0) {
524 			goto unlock_exit;
525 		}
526 	}
527 
528 	/* write the data into interrupt_out_buffer from userspace */
529 	bytes_to_write = min(count, write_buffer_size*dev->interrupt_out_endpoint_size);
530 	if (bytes_to_write < count)
531 		dev_warn(&dev->intf->dev, "Write buffer overflow, %zd bytes dropped\n",count-bytes_to_write);
532 	dbg_info(&dev->intf->dev, "%s: count = %zd, bytes_to_write = %zd\n", __FUNCTION__, count, bytes_to_write);
533 
534 	if (copy_from_user(dev->interrupt_out_buffer, buffer, bytes_to_write)) {
535 		retval = -EFAULT;
536 		goto unlock_exit;
537 	}
538 
539 	if (dev->interrupt_out_endpoint == NULL) {
540 		/* try HID_REQ_SET_REPORT=9 on control_endpoint instead of interrupt_out_endpoint */
541 		retval = usb_control_msg(interface_to_usbdev(dev->intf),
542 					 usb_sndctrlpipe(interface_to_usbdev(dev->intf), 0),
543 					 9,
544 					 USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_OUT,
545 					 1 << 8, 0,
546 					 dev->interrupt_out_buffer,
547 					 bytes_to_write,
548 					 USB_CTRL_SET_TIMEOUT * HZ);
549 		if (retval < 0)
550 			err("Couldn't submit HID_REQ_SET_REPORT %d\n", retval);
551 		goto unlock_exit;
552 	}
553 
554 	/* send off the urb */
555 	usb_fill_int_urb(dev->interrupt_out_urb,
556 			 interface_to_usbdev(dev->intf),
557 			 usb_sndintpipe(interface_to_usbdev(dev->intf),
558 					dev->interrupt_out_endpoint->bEndpointAddress),
559 			 dev->interrupt_out_buffer,
560 			 bytes_to_write,
561 			 ld_usb_interrupt_out_callback,
562 			 dev,
563 			 dev->interrupt_out_interval);
564 
565 	dev->interrupt_out_busy = 1;
566 	wmb();
567 
568 	retval = usb_submit_urb(dev->interrupt_out_urb, GFP_KERNEL);
569 	if (retval) {
570 		dev->interrupt_out_busy = 0;
571 		err("Couldn't submit interrupt_out_urb %d\n", retval);
572 		goto unlock_exit;
573 	}
574 	retval = bytes_to_write;
575 
576 unlock_exit:
577 	/* unlock the device */
578 	up(&dev->sem);
579 
580 exit:
581 	return retval;
582 }
583 
584 /* file operations needed when we register this driver */
585 static struct file_operations ld_usb_fops = {
586 	.owner =	THIS_MODULE,
587 	.read  =	ld_usb_read,
588 	.write =	ld_usb_write,
589 	.open =		ld_usb_open,
590 	.release =	ld_usb_release,
591 	.poll =		ld_usb_poll,
592 };
593 
594 /*
595  * usb class driver info in order to get a minor number from the usb core,
596  * and to have the device registered with devfs and the driver core
597  */
598 static struct usb_class_driver ld_usb_class = {
599 	.name =		"ldusb%d",
600 	.fops =		&ld_usb_fops,
601 	.minor_base =	USB_LD_MINOR_BASE,
602 };
603 
604 /**
605  *	ld_usb_probe
606  *
607  *	Called by the usb core when a new device is connected that it thinks
608  *	this driver might be interested in.
609  */
610 static int ld_usb_probe(struct usb_interface *intf, const struct usb_device_id *id)
611 {
612 	struct usb_device *udev = interface_to_usbdev(intf);
613 	struct ld_usb *dev = NULL;
614 	struct usb_host_interface *iface_desc;
615 	struct usb_endpoint_descriptor *endpoint;
616 	char *buffer;
617 	int i;
618 	int retval = -ENOMEM;
619 
620 	/* allocate memory for our device state and intialize it */
621 
622 	dev = kmalloc(sizeof(*dev), GFP_KERNEL);
623 	if (dev == NULL) {
624 		dev_err(&intf->dev, "Out of memory\n");
625 		goto exit;
626 	}
627 	memset(dev, 0x00, sizeof(*dev));
628 	init_MUTEX(&dev->sem);
629 	dev->intf = intf;
630 	init_waitqueue_head(&dev->read_wait);
631 	init_waitqueue_head(&dev->write_wait);
632 
633 	/* workaround for early firmware versions on fast computers */
634 	if ((le16_to_cpu(udev->descriptor.idVendor) == USB_VENDOR_ID_LD) &&
635 	    ((le16_to_cpu(udev->descriptor.idProduct) == USB_DEVICE_ID_CASSY) ||
636 	     (le16_to_cpu(udev->descriptor.idProduct) == USB_DEVICE_ID_COM3LAB)) &&
637 	    (le16_to_cpu(udev->descriptor.bcdDevice) <= 0x103)) {
638 		buffer = kmalloc(256, GFP_KERNEL);
639 		if (buffer == NULL) {
640 			dev_err(&intf->dev, "Couldn't allocate string buffer\n");
641 			goto error;
642 		}
643 		/* usb_string makes SETUP+STALL to leave always ControlReadLoop */
644 		usb_string(udev, 255, buffer, 256);
645 		kfree(buffer);
646 	}
647 
648 	iface_desc = intf->cur_altsetting;
649 
650 	/* set up the endpoint information */
651 	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
652 		endpoint = &iface_desc->endpoint[i].desc;
653 
654 		if (((endpoint->bEndpointAddress & USB_ENDPOINT_DIR_MASK) == USB_DIR_IN) &&
655 		    ((endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) == USB_ENDPOINT_XFER_INT)) {
656 			dev->interrupt_in_endpoint = endpoint;
657 		}
658 
659 		if (((endpoint->bEndpointAddress & USB_ENDPOINT_DIR_MASK) == USB_DIR_OUT) &&
660 		    ((endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) == USB_ENDPOINT_XFER_INT)) {
661 			dev->interrupt_out_endpoint = endpoint;
662 		}
663 	}
664 	if (dev->interrupt_in_endpoint == NULL) {
665 		dev_err(&intf->dev, "Interrupt in endpoint not found\n");
666 		goto error;
667 	}
668 	if (dev->interrupt_out_endpoint == NULL)
669 		dev_warn(&intf->dev, "Interrupt out endpoint not found (using control endpoint instead)\n");
670 
671 	dev->interrupt_in_endpoint_size = le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize);
672 	dev->ring_buffer = kmalloc(ring_buffer_size*(sizeof(size_t)+dev->interrupt_in_endpoint_size), GFP_KERNEL);
673 	if (!dev->ring_buffer) {
674 		dev_err(&intf->dev, "Couldn't allocate ring_buffer\n");
675 		goto error;
676 	}
677 	dev->interrupt_in_buffer = kmalloc(dev->interrupt_in_endpoint_size, GFP_KERNEL);
678 	if (!dev->interrupt_in_buffer) {
679 		dev_err(&intf->dev, "Couldn't allocate interrupt_in_buffer\n");
680 		goto error;
681 	}
682 	dev->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
683 	if (!dev->interrupt_in_urb) {
684 		dev_err(&intf->dev, "Couldn't allocate interrupt_in_urb\n");
685 		goto error;
686 	}
687 	dev->interrupt_out_endpoint_size = dev->interrupt_out_endpoint ? le16_to_cpu(dev->interrupt_out_endpoint->wMaxPacketSize) :
688 									 udev->descriptor.bMaxPacketSize0;
689 	dev->interrupt_out_buffer = kmalloc(write_buffer_size*dev->interrupt_out_endpoint_size, GFP_KERNEL);
690 	if (!dev->interrupt_out_buffer) {
691 		dev_err(&intf->dev, "Couldn't allocate interrupt_out_buffer\n");
692 		goto error;
693 	}
694 	dev->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
695 	if (!dev->interrupt_out_urb) {
696 		dev_err(&intf->dev, "Couldn't allocate interrupt_out_urb\n");
697 		goto error;
698 	}
699 	dev->interrupt_in_interval = min_interrupt_in_interval > dev->interrupt_in_endpoint->bInterval ? min_interrupt_in_interval : dev->interrupt_in_endpoint->bInterval;
700 	if (dev->interrupt_out_endpoint)
701 		dev->interrupt_out_interval = min_interrupt_out_interval > dev->interrupt_out_endpoint->bInterval ? min_interrupt_out_interval : dev->interrupt_out_endpoint->bInterval;
702 
703 	/* we can register the device now, as it is ready */
704 	usb_set_intfdata(intf, dev);
705 
706 	retval = usb_register_dev(intf, &ld_usb_class);
707 	if (retval) {
708 		/* something prevented us from registering this driver */
709 		dev_err(&intf->dev, "Not able to get a minor for this device.\n");
710 		usb_set_intfdata(intf, NULL);
711 		goto error;
712 	}
713 
714 	/* let the user know what node this device is now attached to */
715 	dev_info(&intf->dev, "LD USB Device #%d now attached to major %d minor %d\n",
716 		(intf->minor - USB_LD_MINOR_BASE), USB_MAJOR, intf->minor);
717 
718 exit:
719 	return retval;
720 
721 error:
722 	ld_usb_delete(dev);
723 
724 	return retval;
725 }
726 
727 /**
728  *	ld_usb_disconnect
729  *
730  *	Called by the usb core when the device is removed from the system.
731  */
732 static void ld_usb_disconnect(struct usb_interface *intf)
733 {
734 	struct ld_usb *dev;
735 	int minor;
736 
737 	down(&disconnect_sem);
738 
739 	dev = usb_get_intfdata(intf);
740 	usb_set_intfdata(intf, NULL);
741 
742 	down(&dev->sem);
743 
744 	minor = intf->minor;
745 
746 	/* give back our minor */
747 	usb_deregister_dev(intf, &ld_usb_class);
748 
749 	/* if the device is not opened, then we clean up right now */
750 	if (!dev->open_count) {
751 		up(&dev->sem);
752 		ld_usb_delete(dev);
753 	} else {
754 		dev->intf = NULL;
755 		up(&dev->sem);
756 	}
757 
758 	up(&disconnect_sem);
759 
760 	dev_info(&intf->dev, "LD USB Device #%d now disconnected\n",
761 		 (minor - USB_LD_MINOR_BASE));
762 }
763 
764 /* usb specific object needed to register this driver with the usb subsystem */
765 static struct usb_driver ld_usb_driver = {
766 	.name =		"ldusb",
767 	.probe =	ld_usb_probe,
768 	.disconnect =	ld_usb_disconnect,
769 	.id_table =	ld_usb_table,
770 };
771 
772 /**
773  *	ld_usb_init
774  */
775 static int __init ld_usb_init(void)
776 {
777 	int retval;
778 
779 	/* register this driver with the USB subsystem */
780 	retval = usb_register(&ld_usb_driver);
781 	if (retval)
782 		err("usb_register failed for the "__FILE__" driver. Error number %d\n", retval);
783 
784 	return retval;
785 }
786 
787 /**
788  *	ld_usb_exit
789  */
790 static void __exit ld_usb_exit(void)
791 {
792 	/* deregister this driver with the USB subsystem */
793 	usb_deregister(&ld_usb_driver);
794 }
795 
796 module_init(ld_usb_init);
797 module_exit(ld_usb_exit);
798 
799