xref: /linux/drivers/usb/misc/ldusb.c (revision f3d9478b2ce468c3115b02ecae7e975990697f15)
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  * V0.13 (mh) Added support for LD X-Ray and Machine Test System
28  */
29 
30 #include <linux/config.h>
31 #include <linux/kernel.h>
32 #include <linux/errno.h>
33 #include <linux/init.h>
34 #include <linux/slab.h>
35 #include <linux/module.h>
36 #include <linux/mutex.h>
37 
38 #include <asm/uaccess.h>
39 #include <linux/input.h>
40 #include <linux/usb.h>
41 #include <linux/poll.h>
42 
43 /* Define these values to match your devices */
44 #define USB_VENDOR_ID_LD		0x0f11	/* USB Vendor ID of LD Didactic GmbH */
45 #define USB_DEVICE_ID_LD_CASSY		0x1000	/* USB Product ID of CASSY-S */
46 #define USB_DEVICE_ID_LD_POCKETCASSY	0x1010	/* USB Product ID of Pocket-CASSY */
47 #define USB_DEVICE_ID_LD_MOBILECASSY	0x1020	/* USB Product ID of Mobile-CASSY */
48 #define USB_DEVICE_ID_LD_JWM		0x1080	/* USB Product ID of Joule and Wattmeter */
49 #define USB_DEVICE_ID_LD_DMMP		0x1081	/* USB Product ID of Digital Multimeter P (reserved) */
50 #define USB_DEVICE_ID_LD_UMIP		0x1090	/* USB Product ID of UMI P */
51 #define USB_DEVICE_ID_LD_XRAY1		0x1100	/* USB Product ID of X-Ray Apparatus */
52 #define USB_DEVICE_ID_LD_XRAY2		0x1101	/* USB Product ID of X-Ray Apparatus */
53 #define USB_DEVICE_ID_LD_VIDEOCOM	0x1200	/* USB Product ID of VideoCom */
54 #define USB_DEVICE_ID_LD_COM3LAB	0x2000	/* USB Product ID of COM3LAB */
55 #define USB_DEVICE_ID_LD_TELEPORT	0x2010	/* USB Product ID of Terminal Adapter */
56 #define USB_DEVICE_ID_LD_NETWORKANALYSER 0x2020	/* USB Product ID of Network Analyser */
57 #define USB_DEVICE_ID_LD_POWERCONTROL	0x2030	/* USB Product ID of Converter Control Unit */
58 #define USB_DEVICE_ID_LD_MACHINETEST	0x2040	/* USB Product ID of Machine Test System */
59 
60 #define USB_VENDOR_ID_VERNIER		0x08f7
61 #define USB_DEVICE_ID_VERNIER_LABPRO	0x0001
62 #define USB_DEVICE_ID_VERNIER_GOTEMP	0x0002
63 #define USB_DEVICE_ID_VERNIER_SKIP	0x0003
64 #define USB_DEVICE_ID_VERNIER_CYCLOPS	0x0004
65 
66 
67 #ifdef CONFIG_USB_DYNAMIC_MINORS
68 #define USB_LD_MINOR_BASE	0
69 #else
70 #define USB_LD_MINOR_BASE	176
71 #endif
72 
73 /* table of devices that work with this driver */
74 static struct usb_device_id ld_usb_table [] = {
75 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_CASSY) },
76 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_POCKETCASSY) },
77 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MOBILECASSY) },
78 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_JWM) },
79 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_DMMP) },
80 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_UMIP) },
81 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_XRAY1) },
82 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_XRAY2) },
83 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_VIDEOCOM) },
84 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_COM3LAB) },
85 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_TELEPORT) },
86 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_NETWORKANALYSER) },
87 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_POWERCONTROL) },
88 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MACHINETEST) },
89 	{ USB_DEVICE(USB_VENDOR_ID_VERNIER, USB_DEVICE_ID_VERNIER_LABPRO) },
90 	{ USB_DEVICE(USB_VENDOR_ID_VERNIER, USB_DEVICE_ID_VERNIER_GOTEMP) },
91 	{ USB_DEVICE(USB_VENDOR_ID_VERNIER, USB_DEVICE_ID_VERNIER_SKIP) },
92 	{ USB_DEVICE(USB_VENDOR_ID_VERNIER, USB_DEVICE_ID_VERNIER_CYCLOPS) },
93 	{ }					/* Terminating entry */
94 };
95 MODULE_DEVICE_TABLE(usb, ld_usb_table);
96 MODULE_VERSION("V0.13");
97 MODULE_AUTHOR("Michael Hund <mhund@ld-didactic.de>");
98 MODULE_DESCRIPTION("LD USB Driver");
99 MODULE_LICENSE("GPL");
100 MODULE_SUPPORTED_DEVICE("LD USB Devices");
101 
102 #ifdef CONFIG_USB_DEBUG
103 	static int debug = 1;
104 #else
105 	static int debug = 0;
106 #endif
107 
108 /* Use our own dbg macro */
109 #define dbg_info(dev, format, arg...) do { if (debug) dev_info(dev , format , ## arg); } while (0)
110 
111 /* Module parameters */
112 module_param(debug, int, S_IRUGO | S_IWUSR);
113 MODULE_PARM_DESC(debug, "Debug enabled or not");
114 
115 /* All interrupt in transfers are collected in a ring buffer to
116  * avoid racing conditions and get better performance of the driver.
117  */
118 static int ring_buffer_size = 128;
119 module_param(ring_buffer_size, int, 0);
120 MODULE_PARM_DESC(ring_buffer_size, "Read ring buffer size in reports");
121 
122 /* The write_buffer can contain more than one interrupt out transfer.
123  */
124 static int write_buffer_size = 10;
125 module_param(write_buffer_size, int, 0);
126 MODULE_PARM_DESC(write_buffer_size, "Write buffer size in reports");
127 
128 /* As of kernel version 2.6.4 ehci-hcd uses an
129  * "only one interrupt transfer per frame" shortcut
130  * to simplify the scheduling of periodic transfers.
131  * This conflicts with our standard 1ms intervals for in and out URBs.
132  * We use default intervals of 2ms for in and 2ms for out transfers,
133  * which should be fast enough.
134  * Increase the interval to allow more devices that do interrupt transfers,
135  * or set to 1 to use the standard interval from the endpoint descriptors.
136  */
137 static int min_interrupt_in_interval = 2;
138 module_param(min_interrupt_in_interval, int, 0);
139 MODULE_PARM_DESC(min_interrupt_in_interval, "Minimum interrupt in interval in ms");
140 
141 static int min_interrupt_out_interval = 2;
142 module_param(min_interrupt_out_interval, int, 0);
143 MODULE_PARM_DESC(min_interrupt_out_interval, "Minimum interrupt out interval in ms");
144 
145 /* Structure to hold all of our device specific stuff */
146 struct ld_usb {
147 	struct semaphore	sem;		/* locks this structure */
148 	struct usb_interface*	intf;		/* save off the usb interface pointer */
149 
150 	int			open_count;	/* number of times this port has been opened */
151 
152 	char*			ring_buffer;
153 	unsigned int		ring_head;
154 	unsigned int		ring_tail;
155 
156 	wait_queue_head_t	read_wait;
157 	wait_queue_head_t	write_wait;
158 
159 	char*			interrupt_in_buffer;
160 	struct usb_endpoint_descriptor* interrupt_in_endpoint;
161 	struct urb*		interrupt_in_urb;
162 	int			interrupt_in_interval;
163 	size_t			interrupt_in_endpoint_size;
164 	int			interrupt_in_running;
165 	int			interrupt_in_done;
166 
167 	char*			interrupt_out_buffer;
168 	struct usb_endpoint_descriptor* interrupt_out_endpoint;
169 	struct urb*		interrupt_out_urb;
170 	int			interrupt_out_interval;
171 	size_t			interrupt_out_endpoint_size;
172 	int			interrupt_out_busy;
173 };
174 
175 /* prevent races between open() and disconnect() */
176 static DEFINE_MUTEX(disconnect_mutex);
177 
178 static struct usb_driver ld_usb_driver;
179 
180 /**
181  *	ld_usb_abort_transfers
182  *      aborts transfers and frees associated data structures
183  */
184 static void ld_usb_abort_transfers(struct ld_usb *dev)
185 {
186 	/* shutdown transfer */
187 	if (dev->interrupt_in_running) {
188 		dev->interrupt_in_running = 0;
189 		if (dev->intf)
190 			usb_kill_urb(dev->interrupt_in_urb);
191 	}
192 	if (dev->interrupt_out_busy)
193 		if (dev->intf)
194 			usb_kill_urb(dev->interrupt_out_urb);
195 }
196 
197 /**
198  *	ld_usb_delete
199  */
200 static void ld_usb_delete(struct ld_usb *dev)
201 {
202 	ld_usb_abort_transfers(dev);
203 
204 	/* free data structures */
205 	usb_free_urb(dev->interrupt_in_urb);
206 	usb_free_urb(dev->interrupt_out_urb);
207 	kfree(dev->ring_buffer);
208 	kfree(dev->interrupt_in_buffer);
209 	kfree(dev->interrupt_out_buffer);
210 	kfree(dev);
211 }
212 
213 /**
214  *	ld_usb_interrupt_in_callback
215  */
216 static void ld_usb_interrupt_in_callback(struct urb *urb, struct pt_regs *regs)
217 {
218 	struct ld_usb *dev = urb->context;
219 	size_t *actual_buffer;
220 	unsigned int next_ring_head;
221 	int retval;
222 
223 	if (urb->status) {
224 		if (urb->status == -ENOENT ||
225 		    urb->status == -ECONNRESET ||
226 		    urb->status == -ESHUTDOWN) {
227 			goto exit;
228 		} else {
229 			dbg_info(&dev->intf->dev, "%s: nonzero status received: %d\n",
230 				 __FUNCTION__, urb->status);
231 			goto resubmit; /* maybe we can recover */
232 		}
233 	}
234 
235 	if (urb->actual_length > 0) {
236 		next_ring_head = (dev->ring_head+1) % ring_buffer_size;
237 		if (next_ring_head != dev->ring_tail) {
238 			actual_buffer = (size_t*)(dev->ring_buffer + dev->ring_head*(sizeof(size_t)+dev->interrupt_in_endpoint_size));
239 			/* actual_buffer gets urb->actual_length + interrupt_in_buffer */
240 			*actual_buffer = urb->actual_length;
241 			memcpy(actual_buffer+1, dev->interrupt_in_buffer, urb->actual_length);
242 			dev->ring_head = next_ring_head;
243 			dbg_info(&dev->intf->dev, "%s: received %d bytes\n",
244 				 __FUNCTION__, urb->actual_length);
245 		} else
246 			dev_warn(&dev->intf->dev,
247 				 "Ring buffer overflow, %d bytes dropped\n",
248 				 urb->actual_length);
249 	}
250 
251 resubmit:
252 	/* resubmit if we're still running */
253 	if (dev->interrupt_in_running && dev->intf) {
254 		retval = usb_submit_urb(dev->interrupt_in_urb, GFP_ATOMIC);
255 		if (retval)
256 			dev_err(&dev->intf->dev,
257 				"usb_submit_urb failed (%d)\n", retval);
258 	}
259 
260 exit:
261 	dev->interrupt_in_done = 1;
262 	wake_up_interruptible(&dev->read_wait);
263 }
264 
265 /**
266  *	ld_usb_interrupt_out_callback
267  */
268 static void ld_usb_interrupt_out_callback(struct urb *urb, struct pt_regs *regs)
269 {
270 	struct ld_usb *dev = urb->context;
271 
272 	/* sync/async unlink faults aren't errors */
273 	if (urb->status && !(urb->status == -ENOENT ||
274 			     urb->status == -ECONNRESET ||
275 			     urb->status == -ESHUTDOWN))
276 		dbg_info(&dev->intf->dev,
277 			 "%s - nonzero write interrupt status received: %d\n",
278 			 __FUNCTION__, urb->status);
279 
280 	dev->interrupt_out_busy = 0;
281 	wake_up_interruptible(&dev->write_wait);
282 }
283 
284 /**
285  *	ld_usb_open
286  */
287 static int ld_usb_open(struct inode *inode, struct file *file)
288 {
289 	struct ld_usb *dev;
290 	int subminor;
291 	int retval = 0;
292 	struct usb_interface *interface;
293 
294 	nonseekable_open(inode, file);
295 	subminor = iminor(inode);
296 
297 	mutex_lock(&disconnect_mutex);
298 
299 	interface = usb_find_interface(&ld_usb_driver, subminor);
300 
301 	if (!interface) {
302 		err("%s - error, can't find device for minor %d\n",
303 		     __FUNCTION__, subminor);
304 		retval = -ENODEV;
305 		goto unlock_disconnect_exit;
306 	}
307 
308 	dev = usb_get_intfdata(interface);
309 
310 	if (!dev) {
311 		retval = -ENODEV;
312 		goto unlock_disconnect_exit;
313 	}
314 
315 	/* lock this device */
316 	if (down_interruptible(&dev->sem)) {
317 		retval = -ERESTARTSYS;
318 		goto unlock_disconnect_exit;
319 	}
320 
321 	/* allow opening only once */
322 	if (dev->open_count) {
323 		retval = -EBUSY;
324 		goto unlock_exit;
325 	}
326 	dev->open_count = 1;
327 
328 	/* initialize in direction */
329 	dev->ring_head = 0;
330 	dev->ring_tail = 0;
331 	usb_fill_int_urb(dev->interrupt_in_urb,
332 			 interface_to_usbdev(interface),
333 			 usb_rcvintpipe(interface_to_usbdev(interface),
334 					dev->interrupt_in_endpoint->bEndpointAddress),
335 			 dev->interrupt_in_buffer,
336 			 dev->interrupt_in_endpoint_size,
337 			 ld_usb_interrupt_in_callback,
338 			 dev,
339 			 dev->interrupt_in_interval);
340 
341 	dev->interrupt_in_running = 1;
342 	dev->interrupt_in_done = 0;
343 
344 	retval = usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
345 	if (retval) {
346 		dev_err(&interface->dev, "Couldn't submit interrupt_in_urb %d\n", retval);
347 		dev->interrupt_in_running = 0;
348 		dev->open_count = 0;
349 		goto unlock_exit;
350 	}
351 
352 	/* save device in the file's private structure */
353 	file->private_data = dev;
354 
355 unlock_exit:
356 	up(&dev->sem);
357 
358 unlock_disconnect_exit:
359 	mutex_unlock(&disconnect_mutex);
360 
361 	return retval;
362 }
363 
364 /**
365  *	ld_usb_release
366  */
367 static int ld_usb_release(struct inode *inode, struct file *file)
368 {
369 	struct ld_usb *dev;
370 	int retval = 0;
371 
372 	dev = file->private_data;
373 
374 	if (dev == NULL) {
375 		retval = -ENODEV;
376 		goto exit;
377 	}
378 
379 	if (down_interruptible(&dev->sem)) {
380 		retval = -ERESTARTSYS;
381 		goto exit;
382 	}
383 
384 	if (dev->open_count != 1) {
385 		retval = -ENODEV;
386 		goto unlock_exit;
387 	}
388 	if (dev->intf == NULL) {
389 		/* the device was unplugged before the file was released */
390 		up(&dev->sem);
391 		/* unlock here as ld_usb_delete frees dev */
392 		ld_usb_delete(dev);
393 		goto exit;
394 	}
395 
396 	/* wait until write transfer is finished */
397 	if (dev->interrupt_out_busy)
398 		wait_event_interruptible_timeout(dev->write_wait, !dev->interrupt_out_busy, 2 * HZ);
399 	ld_usb_abort_transfers(dev);
400 	dev->open_count = 0;
401 
402 unlock_exit:
403 	up(&dev->sem);
404 
405 exit:
406 	return retval;
407 }
408 
409 /**
410  *	ld_usb_poll
411  */
412 static unsigned int ld_usb_poll(struct file *file, poll_table *wait)
413 {
414 	struct ld_usb *dev;
415 	unsigned int mask = 0;
416 
417 	dev = file->private_data;
418 
419 	poll_wait(file, &dev->read_wait, wait);
420 	poll_wait(file, &dev->write_wait, wait);
421 
422 	if (dev->ring_head != dev->ring_tail)
423 		mask |= POLLIN | POLLRDNORM;
424 	if (!dev->interrupt_out_busy)
425 		mask |= POLLOUT | POLLWRNORM;
426 
427 	return mask;
428 }
429 
430 /**
431  *	ld_usb_read
432  */
433 static ssize_t ld_usb_read(struct file *file, char __user *buffer, size_t count,
434 			   loff_t *ppos)
435 {
436 	struct ld_usb *dev;
437 	size_t *actual_buffer;
438 	size_t bytes_to_read;
439 	int retval = 0;
440 
441 	dev = file->private_data;
442 
443 	/* verify that we actually have some data to read */
444 	if (count == 0)
445 		goto exit;
446 
447 	/* lock this object */
448 	if (down_interruptible(&dev->sem)) {
449 		retval = -ERESTARTSYS;
450 		goto exit;
451 	}
452 
453 	/* verify that the device wasn't unplugged */
454 	if (dev->intf == NULL) {
455 		retval = -ENODEV;
456 		err("No device or device unplugged %d\n", retval);
457 		goto unlock_exit;
458 	}
459 
460 	/* wait for data */
461 	if (dev->ring_head == dev->ring_tail) {
462 		if (file->f_flags & O_NONBLOCK) {
463 			retval = -EAGAIN;
464 			goto unlock_exit;
465 		}
466 		retval = wait_event_interruptible(dev->read_wait, dev->interrupt_in_done);
467 		if (retval < 0)
468 			goto unlock_exit;
469 	}
470 
471 	/* actual_buffer contains actual_length + interrupt_in_buffer */
472 	actual_buffer = (size_t*)(dev->ring_buffer + dev->ring_tail*(sizeof(size_t)+dev->interrupt_in_endpoint_size));
473 	bytes_to_read = min(count, *actual_buffer);
474 	if (bytes_to_read < *actual_buffer)
475 		dev_warn(&dev->intf->dev, "Read buffer overflow, %zd bytes dropped\n",
476 			 *actual_buffer-bytes_to_read);
477 
478 	/* copy one interrupt_in_buffer from ring_buffer into userspace */
479 	if (copy_to_user(buffer, actual_buffer+1, bytes_to_read)) {
480 		retval = -EFAULT;
481 		goto unlock_exit;
482 	}
483 	dev->ring_tail = (dev->ring_tail+1) % ring_buffer_size;
484 
485 	retval = bytes_to_read;
486 
487 unlock_exit:
488 	/* unlock the device */
489 	up(&dev->sem);
490 
491 exit:
492 	return retval;
493 }
494 
495 /**
496  *	ld_usb_write
497  */
498 static ssize_t ld_usb_write(struct file *file, const char __user *buffer,
499 			    size_t count, loff_t *ppos)
500 {
501 	struct ld_usb *dev;
502 	size_t bytes_to_write;
503 	int retval = 0;
504 
505 	dev = file->private_data;
506 
507 	/* verify that we actually have some data to write */
508 	if (count == 0)
509 		goto exit;
510 
511 	/* lock this object */
512 	if (down_interruptible(&dev->sem)) {
513 		retval = -ERESTARTSYS;
514 		goto exit;
515 	}
516 
517 	/* verify that the device wasn't unplugged */
518 	if (dev->intf == NULL) {
519 		retval = -ENODEV;
520 		err("No device or device unplugged %d\n", retval);
521 		goto unlock_exit;
522 	}
523 
524 	/* wait until previous transfer is finished */
525 	if (dev->interrupt_out_busy) {
526 		if (file->f_flags & O_NONBLOCK) {
527 			retval = -EAGAIN;
528 			goto unlock_exit;
529 		}
530 		retval = wait_event_interruptible(dev->write_wait, !dev->interrupt_out_busy);
531 		if (retval < 0) {
532 			goto unlock_exit;
533 		}
534 	}
535 
536 	/* write the data into interrupt_out_buffer from userspace */
537 	bytes_to_write = min(count, write_buffer_size*dev->interrupt_out_endpoint_size);
538 	if (bytes_to_write < count)
539 		dev_warn(&dev->intf->dev, "Write buffer overflow, %zd bytes dropped\n",count-bytes_to_write);
540 	dbg_info(&dev->intf->dev, "%s: count = %zd, bytes_to_write = %zd\n", __FUNCTION__, count, bytes_to_write);
541 
542 	if (copy_from_user(dev->interrupt_out_buffer, buffer, bytes_to_write)) {
543 		retval = -EFAULT;
544 		goto unlock_exit;
545 	}
546 
547 	if (dev->interrupt_out_endpoint == NULL) {
548 		/* try HID_REQ_SET_REPORT=9 on control_endpoint instead of interrupt_out_endpoint */
549 		retval = usb_control_msg(interface_to_usbdev(dev->intf),
550 					 usb_sndctrlpipe(interface_to_usbdev(dev->intf), 0),
551 					 9,
552 					 USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_OUT,
553 					 1 << 8, 0,
554 					 dev->interrupt_out_buffer,
555 					 bytes_to_write,
556 					 USB_CTRL_SET_TIMEOUT * HZ);
557 		if (retval < 0)
558 			err("Couldn't submit HID_REQ_SET_REPORT %d\n", retval);
559 		goto unlock_exit;
560 	}
561 
562 	/* send off the urb */
563 	usb_fill_int_urb(dev->interrupt_out_urb,
564 			 interface_to_usbdev(dev->intf),
565 			 usb_sndintpipe(interface_to_usbdev(dev->intf),
566 					dev->interrupt_out_endpoint->bEndpointAddress),
567 			 dev->interrupt_out_buffer,
568 			 bytes_to_write,
569 			 ld_usb_interrupt_out_callback,
570 			 dev,
571 			 dev->interrupt_out_interval);
572 
573 	dev->interrupt_out_busy = 1;
574 	wmb();
575 
576 	retval = usb_submit_urb(dev->interrupt_out_urb, GFP_KERNEL);
577 	if (retval) {
578 		dev->interrupt_out_busy = 0;
579 		err("Couldn't submit interrupt_out_urb %d\n", retval);
580 		goto unlock_exit;
581 	}
582 	retval = bytes_to_write;
583 
584 unlock_exit:
585 	/* unlock the device */
586 	up(&dev->sem);
587 
588 exit:
589 	return retval;
590 }
591 
592 /* file operations needed when we register this driver */
593 static struct file_operations ld_usb_fops = {
594 	.owner =	THIS_MODULE,
595 	.read  =	ld_usb_read,
596 	.write =	ld_usb_write,
597 	.open =		ld_usb_open,
598 	.release =	ld_usb_release,
599 	.poll =		ld_usb_poll,
600 };
601 
602 /*
603  * usb class driver info in order to get a minor number from the usb core,
604  * and to have the device registered with the driver core
605  */
606 static struct usb_class_driver ld_usb_class = {
607 	.name =		"ldusb%d",
608 	.fops =		&ld_usb_fops,
609 	.minor_base =	USB_LD_MINOR_BASE,
610 };
611 
612 /**
613  *	ld_usb_probe
614  *
615  *	Called by the usb core when a new device is connected that it thinks
616  *	this driver might be interested in.
617  */
618 static int ld_usb_probe(struct usb_interface *intf, const struct usb_device_id *id)
619 {
620 	struct usb_device *udev = interface_to_usbdev(intf);
621 	struct ld_usb *dev = NULL;
622 	struct usb_host_interface *iface_desc;
623 	struct usb_endpoint_descriptor *endpoint;
624 	char *buffer;
625 	int i;
626 	int retval = -ENOMEM;
627 
628 	/* allocate memory for our device state and intialize it */
629 
630 	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
631 	if (dev == NULL) {
632 		dev_err(&intf->dev, "Out of memory\n");
633 		goto exit;
634 	}
635 	init_MUTEX(&dev->sem);
636 	dev->intf = intf;
637 	init_waitqueue_head(&dev->read_wait);
638 	init_waitqueue_head(&dev->write_wait);
639 
640 	/* workaround for early firmware versions on fast computers */
641 	if ((le16_to_cpu(udev->descriptor.idVendor) == USB_VENDOR_ID_LD) &&
642 	    ((le16_to_cpu(udev->descriptor.idProduct) == USB_DEVICE_ID_LD_CASSY) ||
643 	     (le16_to_cpu(udev->descriptor.idProduct) == USB_DEVICE_ID_LD_COM3LAB)) &&
644 	    (le16_to_cpu(udev->descriptor.bcdDevice) <= 0x103)) {
645 		buffer = kmalloc(256, GFP_KERNEL);
646 		if (buffer == NULL) {
647 			dev_err(&intf->dev, "Couldn't allocate string buffer\n");
648 			goto error;
649 		}
650 		/* usb_string makes SETUP+STALL to leave always ControlReadLoop */
651 		usb_string(udev, 255, buffer, 256);
652 		kfree(buffer);
653 	}
654 
655 	iface_desc = intf->cur_altsetting;
656 
657 	/* set up the endpoint information */
658 	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
659 		endpoint = &iface_desc->endpoint[i].desc;
660 
661 		if (((endpoint->bEndpointAddress & USB_ENDPOINT_DIR_MASK) == USB_DIR_IN) &&
662 		    ((endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) == USB_ENDPOINT_XFER_INT)) {
663 			dev->interrupt_in_endpoint = endpoint;
664 		}
665 
666 		if (((endpoint->bEndpointAddress & USB_ENDPOINT_DIR_MASK) == USB_DIR_OUT) &&
667 		    ((endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) == USB_ENDPOINT_XFER_INT)) {
668 			dev->interrupt_out_endpoint = endpoint;
669 		}
670 	}
671 	if (dev->interrupt_in_endpoint == NULL) {
672 		dev_err(&intf->dev, "Interrupt in endpoint not found\n");
673 		goto error;
674 	}
675 	if (dev->interrupt_out_endpoint == NULL)
676 		dev_warn(&intf->dev, "Interrupt out endpoint not found (using control endpoint instead)\n");
677 
678 	dev->interrupt_in_endpoint_size = le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize);
679 	dev->ring_buffer = kmalloc(ring_buffer_size*(sizeof(size_t)+dev->interrupt_in_endpoint_size), GFP_KERNEL);
680 	if (!dev->ring_buffer) {
681 		dev_err(&intf->dev, "Couldn't allocate ring_buffer\n");
682 		goto error;
683 	}
684 	dev->interrupt_in_buffer = kmalloc(dev->interrupt_in_endpoint_size, GFP_KERNEL);
685 	if (!dev->interrupt_in_buffer) {
686 		dev_err(&intf->dev, "Couldn't allocate interrupt_in_buffer\n");
687 		goto error;
688 	}
689 	dev->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
690 	if (!dev->interrupt_in_urb) {
691 		dev_err(&intf->dev, "Couldn't allocate interrupt_in_urb\n");
692 		goto error;
693 	}
694 	dev->interrupt_out_endpoint_size = dev->interrupt_out_endpoint ? le16_to_cpu(dev->interrupt_out_endpoint->wMaxPacketSize) :
695 									 udev->descriptor.bMaxPacketSize0;
696 	dev->interrupt_out_buffer = kmalloc(write_buffer_size*dev->interrupt_out_endpoint_size, GFP_KERNEL);
697 	if (!dev->interrupt_out_buffer) {
698 		dev_err(&intf->dev, "Couldn't allocate interrupt_out_buffer\n");
699 		goto error;
700 	}
701 	dev->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
702 	if (!dev->interrupt_out_urb) {
703 		dev_err(&intf->dev, "Couldn't allocate interrupt_out_urb\n");
704 		goto error;
705 	}
706 	dev->interrupt_in_interval = min_interrupt_in_interval > dev->interrupt_in_endpoint->bInterval ? min_interrupt_in_interval : dev->interrupt_in_endpoint->bInterval;
707 	if (dev->interrupt_out_endpoint)
708 		dev->interrupt_out_interval = min_interrupt_out_interval > dev->interrupt_out_endpoint->bInterval ? min_interrupt_out_interval : dev->interrupt_out_endpoint->bInterval;
709 
710 	/* we can register the device now, as it is ready */
711 	usb_set_intfdata(intf, dev);
712 
713 	retval = usb_register_dev(intf, &ld_usb_class);
714 	if (retval) {
715 		/* something prevented us from registering this driver */
716 		dev_err(&intf->dev, "Not able to get a minor for this device.\n");
717 		usb_set_intfdata(intf, NULL);
718 		goto error;
719 	}
720 
721 	/* let the user know what node this device is now attached to */
722 	dev_info(&intf->dev, "LD USB Device #%d now attached to major %d minor %d\n",
723 		(intf->minor - USB_LD_MINOR_BASE), USB_MAJOR, intf->minor);
724 
725 exit:
726 	return retval;
727 
728 error:
729 	ld_usb_delete(dev);
730 
731 	return retval;
732 }
733 
734 /**
735  *	ld_usb_disconnect
736  *
737  *	Called by the usb core when the device is removed from the system.
738  */
739 static void ld_usb_disconnect(struct usb_interface *intf)
740 {
741 	struct ld_usb *dev;
742 	int minor;
743 
744 	mutex_lock(&disconnect_mutex);
745 
746 	dev = usb_get_intfdata(intf);
747 	usb_set_intfdata(intf, NULL);
748 
749 	down(&dev->sem);
750 
751 	minor = intf->minor;
752 
753 	/* give back our minor */
754 	usb_deregister_dev(intf, &ld_usb_class);
755 
756 	/* if the device is not opened, then we clean up right now */
757 	if (!dev->open_count) {
758 		up(&dev->sem);
759 		ld_usb_delete(dev);
760 	} else {
761 		dev->intf = NULL;
762 		up(&dev->sem);
763 	}
764 
765 	mutex_unlock(&disconnect_mutex);
766 
767 	dev_info(&intf->dev, "LD USB Device #%d now disconnected\n",
768 		 (minor - USB_LD_MINOR_BASE));
769 }
770 
771 /* usb specific object needed to register this driver with the usb subsystem */
772 static struct usb_driver ld_usb_driver = {
773 	.name =		"ldusb",
774 	.probe =	ld_usb_probe,
775 	.disconnect =	ld_usb_disconnect,
776 	.id_table =	ld_usb_table,
777 };
778 
779 /**
780  *	ld_usb_init
781  */
782 static int __init ld_usb_init(void)
783 {
784 	int retval;
785 
786 	/* register this driver with the USB subsystem */
787 	retval = usb_register(&ld_usb_driver);
788 	if (retval)
789 		err("usb_register failed for the "__FILE__" driver. Error number %d\n", retval);
790 
791 	return retval;
792 }
793 
794 /**
795  *	ld_usb_exit
796  */
797 static void __exit ld_usb_exit(void)
798 {
799 	/* deregister this driver with the USB subsystem */
800 	usb_deregister(&ld_usb_driver);
801 }
802 
803 module_init(ld_usb_init);
804 module_exit(ld_usb_exit);
805 
806