xref: /linux/drivers/usb/misc/ldusb.c (revision 9e9f60108423f18a99c9cc93ef7f23490ecc709b)
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 
25 #include <linux/kernel.h>
26 #include <linux/errno.h>
27 #include <linux/slab.h>
28 #include <linux/module.h>
29 #include <linux/mutex.h>
30 
31 #include <asm/uaccess.h>
32 #include <linux/input.h>
33 #include <linux/usb.h>
34 #include <linux/poll.h>
35 
36 /* Define these values to match your devices */
37 #define USB_VENDOR_ID_LD		0x0f11	/* USB Vendor ID of LD Didactic GmbH */
38 #define USB_DEVICE_ID_LD_CASSY		0x1000	/* USB Product ID of CASSY-S modules with 8 bytes endpoint size */
39 #define USB_DEVICE_ID_LD_CASSY2		0x1001	/* USB Product ID of CASSY-S modules with 64 bytes endpoint size */
40 #define USB_DEVICE_ID_LD_POCKETCASSY	0x1010	/* USB Product ID of Pocket-CASSY */
41 #define USB_DEVICE_ID_LD_POCKETCASSY2	0x1011	/* USB Product ID of Pocket-CASSY 2 (reserved) */
42 #define USB_DEVICE_ID_LD_MOBILECASSY	0x1020	/* USB Product ID of Mobile-CASSY */
43 #define USB_DEVICE_ID_LD_MOBILECASSY2	0x1021	/* USB Product ID of Mobile-CASSY 2 (reserved) */
44 #define USB_DEVICE_ID_LD_MICROCASSYVOLTAGE	0x1031	/* USB Product ID of Micro-CASSY Voltage */
45 #define USB_DEVICE_ID_LD_MICROCASSYCURRENT	0x1032	/* USB Product ID of Micro-CASSY Current */
46 #define USB_DEVICE_ID_LD_MICROCASSYTIME		0x1033	/* USB Product ID of Micro-CASSY Time (reserved) */
47 #define USB_DEVICE_ID_LD_MICROCASSYTEMPERATURE	0x1035	/* USB Product ID of Micro-CASSY Temperature */
48 #define USB_DEVICE_ID_LD_MICROCASSYPH		0x1038	/* USB Product ID of Micro-CASSY pH */
49 #define USB_DEVICE_ID_LD_JWM		0x1080	/* USB Product ID of Joule and Wattmeter */
50 #define USB_DEVICE_ID_LD_DMMP		0x1081	/* USB Product ID of Digital Multimeter P (reserved) */
51 #define USB_DEVICE_ID_LD_UMIP		0x1090	/* USB Product ID of UMI P */
52 #define USB_DEVICE_ID_LD_UMIC		0x10A0	/* USB Product ID of UMI C */
53 #define USB_DEVICE_ID_LD_UMIB		0x10B0	/* USB Product ID of UMI B */
54 #define USB_DEVICE_ID_LD_XRAY		0x1100	/* USB Product ID of X-Ray Apparatus 55481 */
55 #define USB_DEVICE_ID_LD_XRAY2		0x1101	/* USB Product ID of X-Ray Apparatus 554800 */
56 #define USB_DEVICE_ID_LD_XRAYCT		0x1110	/* USB Product ID of X-Ray Apparatus CT 554821*/
57 #define USB_DEVICE_ID_LD_VIDEOCOM	0x1200	/* USB Product ID of VideoCom */
58 #define USB_DEVICE_ID_LD_MOTOR		0x1210	/* USB Product ID of Motor (reserved) */
59 #define USB_DEVICE_ID_LD_COM3LAB	0x2000	/* USB Product ID of COM3LAB */
60 #define USB_DEVICE_ID_LD_TELEPORT	0x2010	/* USB Product ID of Terminal Adapter */
61 #define USB_DEVICE_ID_LD_NETWORKANALYSER 0x2020	/* USB Product ID of Network Analyser */
62 #define USB_DEVICE_ID_LD_POWERCONTROL	0x2030	/* USB Product ID of Converter Control Unit */
63 #define USB_DEVICE_ID_LD_MACHINETEST	0x2040	/* USB Product ID of Machine Test System */
64 #define USB_DEVICE_ID_LD_MOSTANALYSER	0x2050	/* USB Product ID of MOST Protocol Analyser */
65 #define USB_DEVICE_ID_LD_MOSTANALYSER2	0x2051	/* USB Product ID of MOST Protocol Analyser 2 */
66 #define USB_DEVICE_ID_LD_ABSESP		0x2060	/* USB Product ID of ABS ESP */
67 #define USB_DEVICE_ID_LD_AUTODATABUS	0x2070	/* USB Product ID of Automotive Data Buses */
68 #define USB_DEVICE_ID_LD_MCT		0x2080	/* USB Product ID of Microcontroller technique */
69 #define USB_DEVICE_ID_LD_HYBRID		0x2090	/* USB Product ID of Automotive Hybrid */
70 #define USB_DEVICE_ID_LD_HEATCONTROL	0x20A0	/* USB Product ID of Heat control */
71 
72 #define USB_VENDOR_ID_VERNIER		0x08f7
73 #define USB_DEVICE_ID_VERNIER_GOTEMP	0x0002
74 #define USB_DEVICE_ID_VERNIER_SKIP	0x0003
75 #define USB_DEVICE_ID_VERNIER_CYCLOPS	0x0004
76 #define USB_DEVICE_ID_VERNIER_LCSPEC	0x0006
77 
78 #ifdef CONFIG_USB_DYNAMIC_MINORS
79 #define USB_LD_MINOR_BASE	0
80 #else
81 #define USB_LD_MINOR_BASE	176
82 #endif
83 
84 /* table of devices that work with this driver */
85 static const struct usb_device_id ld_usb_table[] = {
86 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_CASSY) },
87 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_CASSY2) },
88 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_POCKETCASSY) },
89 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_POCKETCASSY2) },
90 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MOBILECASSY) },
91 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MOBILECASSY2) },
92 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MICROCASSYVOLTAGE) },
93 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MICROCASSYCURRENT) },
94 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MICROCASSYTIME) },
95 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MICROCASSYTEMPERATURE) },
96 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MICROCASSYPH) },
97 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_JWM) },
98 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_DMMP) },
99 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_UMIP) },
100 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_UMIC) },
101 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_UMIB) },
102 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_XRAY) },
103 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_XRAY2) },
104 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_VIDEOCOM) },
105 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MOTOR) },
106 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_COM3LAB) },
107 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_TELEPORT) },
108 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_NETWORKANALYSER) },
109 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_POWERCONTROL) },
110 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MACHINETEST) },
111 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MOSTANALYSER) },
112 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MOSTANALYSER2) },
113 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_ABSESP) },
114 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_AUTODATABUS) },
115 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MCT) },
116 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_HYBRID) },
117 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_HEATCONTROL) },
118 	{ USB_DEVICE(USB_VENDOR_ID_VERNIER, USB_DEVICE_ID_VERNIER_GOTEMP) },
119 	{ USB_DEVICE(USB_VENDOR_ID_VERNIER, USB_DEVICE_ID_VERNIER_SKIP) },
120 	{ USB_DEVICE(USB_VENDOR_ID_VERNIER, USB_DEVICE_ID_VERNIER_CYCLOPS) },
121 	{ USB_DEVICE(USB_VENDOR_ID_VERNIER, USB_DEVICE_ID_VERNIER_LCSPEC) },
122 	{ }					/* Terminating entry */
123 };
124 MODULE_DEVICE_TABLE(usb, ld_usb_table);
125 MODULE_VERSION("V0.14");
126 MODULE_AUTHOR("Michael Hund <mhund@ld-didactic.de>");
127 MODULE_DESCRIPTION("LD USB Driver");
128 MODULE_LICENSE("GPL");
129 MODULE_SUPPORTED_DEVICE("LD USB Devices");
130 
131 /* All interrupt in transfers are collected in a ring buffer to
132  * avoid racing conditions and get better performance of the driver.
133  */
134 static int ring_buffer_size = 128;
135 module_param(ring_buffer_size, int, 0);
136 MODULE_PARM_DESC(ring_buffer_size, "Read ring buffer size in reports");
137 
138 /* The write_buffer can contain more than one interrupt out transfer.
139  */
140 static int write_buffer_size = 10;
141 module_param(write_buffer_size, int, 0);
142 MODULE_PARM_DESC(write_buffer_size, "Write buffer size in reports");
143 
144 /* As of kernel version 2.6.4 ehci-hcd uses an
145  * "only one interrupt transfer per frame" shortcut
146  * to simplify the scheduling of periodic transfers.
147  * This conflicts with our standard 1ms intervals for in and out URBs.
148  * We use default intervals of 2ms for in and 2ms for out transfers,
149  * which should be fast enough.
150  * Increase the interval to allow more devices that do interrupt transfers,
151  * or set to 1 to use the standard interval from the endpoint descriptors.
152  */
153 static int min_interrupt_in_interval = 2;
154 module_param(min_interrupt_in_interval, int, 0);
155 MODULE_PARM_DESC(min_interrupt_in_interval, "Minimum interrupt in interval in ms");
156 
157 static int min_interrupt_out_interval = 2;
158 module_param(min_interrupt_out_interval, int, 0);
159 MODULE_PARM_DESC(min_interrupt_out_interval, "Minimum interrupt out interval in ms");
160 
161 /* Structure to hold all of our device specific stuff */
162 struct ld_usb {
163 	struct mutex		mutex;		/* locks this structure */
164 	struct usb_interface*	intf;		/* save off the usb interface pointer */
165 
166 	int			open_count;	/* number of times this port has been opened */
167 
168 	char*			ring_buffer;
169 	unsigned int		ring_head;
170 	unsigned int		ring_tail;
171 
172 	wait_queue_head_t	read_wait;
173 	wait_queue_head_t	write_wait;
174 
175 	char*			interrupt_in_buffer;
176 	struct usb_endpoint_descriptor* interrupt_in_endpoint;
177 	struct urb*		interrupt_in_urb;
178 	int			interrupt_in_interval;
179 	size_t			interrupt_in_endpoint_size;
180 	int			interrupt_in_running;
181 	int			interrupt_in_done;
182 	int			buffer_overflow;
183 	spinlock_t		rbsl;
184 
185 	char*			interrupt_out_buffer;
186 	struct usb_endpoint_descriptor* interrupt_out_endpoint;
187 	struct urb*		interrupt_out_urb;
188 	int			interrupt_out_interval;
189 	size_t			interrupt_out_endpoint_size;
190 	int			interrupt_out_busy;
191 };
192 
193 static struct usb_driver ld_usb_driver;
194 
195 /**
196  *	ld_usb_abort_transfers
197  *      aborts transfers and frees associated data structures
198  */
199 static void ld_usb_abort_transfers(struct ld_usb *dev)
200 {
201 	/* shutdown transfer */
202 	if (dev->interrupt_in_running) {
203 		dev->interrupt_in_running = 0;
204 		if (dev->intf)
205 			usb_kill_urb(dev->interrupt_in_urb);
206 	}
207 	if (dev->interrupt_out_busy)
208 		if (dev->intf)
209 			usb_kill_urb(dev->interrupt_out_urb);
210 }
211 
212 /**
213  *	ld_usb_delete
214  */
215 static void ld_usb_delete(struct ld_usb *dev)
216 {
217 	ld_usb_abort_transfers(dev);
218 
219 	/* free data structures */
220 	usb_free_urb(dev->interrupt_in_urb);
221 	usb_free_urb(dev->interrupt_out_urb);
222 	kfree(dev->ring_buffer);
223 	kfree(dev->interrupt_in_buffer);
224 	kfree(dev->interrupt_out_buffer);
225 	kfree(dev);
226 }
227 
228 /**
229  *	ld_usb_interrupt_in_callback
230  */
231 static void ld_usb_interrupt_in_callback(struct urb *urb)
232 {
233 	struct ld_usb *dev = urb->context;
234 	size_t *actual_buffer;
235 	unsigned int next_ring_head;
236 	int status = urb->status;
237 	int retval;
238 
239 	if (status) {
240 		if (status == -ENOENT ||
241 		    status == -ECONNRESET ||
242 		    status == -ESHUTDOWN) {
243 			goto exit;
244 		} else {
245 			dev_dbg(&dev->intf->dev,
246 				"%s: nonzero status received: %d\n", __func__,
247 				status);
248 			spin_lock(&dev->rbsl);
249 			goto resubmit; /* maybe we can recover */
250 		}
251 	}
252 
253 	spin_lock(&dev->rbsl);
254 	if (urb->actual_length > 0) {
255 		next_ring_head = (dev->ring_head+1) % ring_buffer_size;
256 		if (next_ring_head != dev->ring_tail) {
257 			actual_buffer = (size_t*)(dev->ring_buffer + dev->ring_head*(sizeof(size_t)+dev->interrupt_in_endpoint_size));
258 			/* actual_buffer gets urb->actual_length + interrupt_in_buffer */
259 			*actual_buffer = urb->actual_length;
260 			memcpy(actual_buffer+1, dev->interrupt_in_buffer, urb->actual_length);
261 			dev->ring_head = next_ring_head;
262 			dev_dbg(&dev->intf->dev, "%s: received %d bytes\n",
263 				__func__, urb->actual_length);
264 		} else {
265 			dev_warn(&dev->intf->dev,
266 				 "Ring buffer overflow, %d bytes dropped\n",
267 				 urb->actual_length);
268 			dev->buffer_overflow = 1;
269 		}
270 	}
271 
272 resubmit:
273 	/* resubmit if we're still running */
274 	if (dev->interrupt_in_running && !dev->buffer_overflow && dev->intf) {
275 		retval = usb_submit_urb(dev->interrupt_in_urb, GFP_ATOMIC);
276 		if (retval) {
277 			dev_err(&dev->intf->dev,
278 				"usb_submit_urb failed (%d)\n", retval);
279 			dev->buffer_overflow = 1;
280 		}
281 	}
282 	spin_unlock(&dev->rbsl);
283 exit:
284 	dev->interrupt_in_done = 1;
285 	wake_up_interruptible(&dev->read_wait);
286 }
287 
288 /**
289  *	ld_usb_interrupt_out_callback
290  */
291 static void ld_usb_interrupt_out_callback(struct urb *urb)
292 {
293 	struct ld_usb *dev = urb->context;
294 	int status = urb->status;
295 
296 	/* sync/async unlink faults aren't errors */
297 	if (status && !(status == -ENOENT ||
298 			status == -ECONNRESET ||
299 			status == -ESHUTDOWN))
300 		dev_dbg(&dev->intf->dev,
301 			"%s - nonzero write interrupt status received: %d\n",
302 			__func__, status);
303 
304 	dev->interrupt_out_busy = 0;
305 	wake_up_interruptible(&dev->write_wait);
306 }
307 
308 /**
309  *	ld_usb_open
310  */
311 static int ld_usb_open(struct inode *inode, struct file *file)
312 {
313 	struct ld_usb *dev;
314 	int subminor;
315 	int retval;
316 	struct usb_interface *interface;
317 
318 	nonseekable_open(inode, file);
319 	subminor = iminor(inode);
320 
321 	interface = usb_find_interface(&ld_usb_driver, subminor);
322 
323 	if (!interface) {
324 		printk(KERN_ERR "%s - error, can't find device for minor %d\n",
325 		       __func__, subminor);
326 		return -ENODEV;
327 	}
328 
329 	dev = usb_get_intfdata(interface);
330 
331 	if (!dev)
332 		return -ENODEV;
333 
334 	/* lock this device */
335 	if (mutex_lock_interruptible(&dev->mutex))
336 		return -ERESTARTSYS;
337 
338 	/* allow opening only once */
339 	if (dev->open_count) {
340 		retval = -EBUSY;
341 		goto unlock_exit;
342 	}
343 	dev->open_count = 1;
344 
345 	/* initialize in direction */
346 	dev->ring_head = 0;
347 	dev->ring_tail = 0;
348 	dev->buffer_overflow = 0;
349 	usb_fill_int_urb(dev->interrupt_in_urb,
350 			 interface_to_usbdev(interface),
351 			 usb_rcvintpipe(interface_to_usbdev(interface),
352 					dev->interrupt_in_endpoint->bEndpointAddress),
353 			 dev->interrupt_in_buffer,
354 			 dev->interrupt_in_endpoint_size,
355 			 ld_usb_interrupt_in_callback,
356 			 dev,
357 			 dev->interrupt_in_interval);
358 
359 	dev->interrupt_in_running = 1;
360 	dev->interrupt_in_done = 0;
361 
362 	retval = usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
363 	if (retval) {
364 		dev_err(&interface->dev, "Couldn't submit interrupt_in_urb %d\n", retval);
365 		dev->interrupt_in_running = 0;
366 		dev->open_count = 0;
367 		goto unlock_exit;
368 	}
369 
370 	/* save device in the file's private structure */
371 	file->private_data = dev;
372 
373 unlock_exit:
374 	mutex_unlock(&dev->mutex);
375 
376 	return retval;
377 }
378 
379 /**
380  *	ld_usb_release
381  */
382 static int ld_usb_release(struct inode *inode, struct file *file)
383 {
384 	struct ld_usb *dev;
385 	int retval = 0;
386 
387 	dev = file->private_data;
388 
389 	if (dev == NULL) {
390 		retval = -ENODEV;
391 		goto exit;
392 	}
393 
394 	if (mutex_lock_interruptible(&dev->mutex)) {
395 		retval = -ERESTARTSYS;
396 		goto exit;
397 	}
398 
399 	if (dev->open_count != 1) {
400 		retval = -ENODEV;
401 		goto unlock_exit;
402 	}
403 	if (dev->intf == NULL) {
404 		/* the device was unplugged before the file was released */
405 		mutex_unlock(&dev->mutex);
406 		/* unlock here as ld_usb_delete frees dev */
407 		ld_usb_delete(dev);
408 		goto exit;
409 	}
410 
411 	/* wait until write transfer is finished */
412 	if (dev->interrupt_out_busy)
413 		wait_event_interruptible_timeout(dev->write_wait, !dev->interrupt_out_busy, 2 * HZ);
414 	ld_usb_abort_transfers(dev);
415 	dev->open_count = 0;
416 
417 unlock_exit:
418 	mutex_unlock(&dev->mutex);
419 
420 exit:
421 	return retval;
422 }
423 
424 /**
425  *	ld_usb_poll
426  */
427 static unsigned int ld_usb_poll(struct file *file, poll_table *wait)
428 {
429 	struct ld_usb *dev;
430 	unsigned int mask = 0;
431 
432 	dev = file->private_data;
433 
434 	if (!dev->intf)
435 		return POLLERR | POLLHUP;
436 
437 	poll_wait(file, &dev->read_wait, wait);
438 	poll_wait(file, &dev->write_wait, wait);
439 
440 	if (dev->ring_head != dev->ring_tail)
441 		mask |= POLLIN | POLLRDNORM;
442 	if (!dev->interrupt_out_busy)
443 		mask |= POLLOUT | POLLWRNORM;
444 
445 	return mask;
446 }
447 
448 /**
449  *	ld_usb_read
450  */
451 static ssize_t ld_usb_read(struct file *file, char __user *buffer, size_t count,
452 			   loff_t *ppos)
453 {
454 	struct ld_usb *dev;
455 	size_t *actual_buffer;
456 	size_t bytes_to_read;
457 	int retval = 0;
458 	int rv;
459 
460 	dev = file->private_data;
461 
462 	/* verify that we actually have some data to read */
463 	if (count == 0)
464 		goto exit;
465 
466 	/* lock this object */
467 	if (mutex_lock_interruptible(&dev->mutex)) {
468 		retval = -ERESTARTSYS;
469 		goto exit;
470 	}
471 
472 	/* verify that the device wasn't unplugged */
473 	if (dev->intf == NULL) {
474 		retval = -ENODEV;
475 		printk(KERN_ERR "ldusb: No device or device unplugged %d\n", retval);
476 		goto unlock_exit;
477 	}
478 
479 	/* wait for data */
480 	spin_lock_irq(&dev->rbsl);
481 	if (dev->ring_head == dev->ring_tail) {
482 		dev->interrupt_in_done = 0;
483 		spin_unlock_irq(&dev->rbsl);
484 		if (file->f_flags & O_NONBLOCK) {
485 			retval = -EAGAIN;
486 			goto unlock_exit;
487 		}
488 		retval = wait_event_interruptible(dev->read_wait, dev->interrupt_in_done);
489 		if (retval < 0)
490 			goto unlock_exit;
491 	} else {
492 		spin_unlock_irq(&dev->rbsl);
493 	}
494 
495 	/* actual_buffer contains actual_length + interrupt_in_buffer */
496 	actual_buffer = (size_t*)(dev->ring_buffer + dev->ring_tail*(sizeof(size_t)+dev->interrupt_in_endpoint_size));
497 	bytes_to_read = min(count, *actual_buffer);
498 	if (bytes_to_read < *actual_buffer)
499 		dev_warn(&dev->intf->dev, "Read buffer overflow, %zd bytes dropped\n",
500 			 *actual_buffer-bytes_to_read);
501 
502 	/* copy one interrupt_in_buffer from ring_buffer into userspace */
503 	if (copy_to_user(buffer, actual_buffer+1, bytes_to_read)) {
504 		retval = -EFAULT;
505 		goto unlock_exit;
506 	}
507 	dev->ring_tail = (dev->ring_tail+1) % ring_buffer_size;
508 
509 	retval = bytes_to_read;
510 
511 	spin_lock_irq(&dev->rbsl);
512 	if (dev->buffer_overflow) {
513 		dev->buffer_overflow = 0;
514 		spin_unlock_irq(&dev->rbsl);
515 		rv = usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
516 		if (rv < 0)
517 			dev->buffer_overflow = 1;
518 	} else {
519 		spin_unlock_irq(&dev->rbsl);
520 	}
521 
522 unlock_exit:
523 	/* unlock the device */
524 	mutex_unlock(&dev->mutex);
525 
526 exit:
527 	return retval;
528 }
529 
530 /**
531  *	ld_usb_write
532  */
533 static ssize_t ld_usb_write(struct file *file, const char __user *buffer,
534 			    size_t count, loff_t *ppos)
535 {
536 	struct ld_usb *dev;
537 	size_t bytes_to_write;
538 	int retval = 0;
539 
540 	dev = file->private_data;
541 
542 	/* verify that we actually have some data to write */
543 	if (count == 0)
544 		goto exit;
545 
546 	/* lock this object */
547 	if (mutex_lock_interruptible(&dev->mutex)) {
548 		retval = -ERESTARTSYS;
549 		goto exit;
550 	}
551 
552 	/* verify that the device wasn't unplugged */
553 	if (dev->intf == NULL) {
554 		retval = -ENODEV;
555 		printk(KERN_ERR "ldusb: No device or device unplugged %d\n", retval);
556 		goto unlock_exit;
557 	}
558 
559 	/* wait until previous transfer is finished */
560 	if (dev->interrupt_out_busy) {
561 		if (file->f_flags & O_NONBLOCK) {
562 			retval = -EAGAIN;
563 			goto unlock_exit;
564 		}
565 		retval = wait_event_interruptible(dev->write_wait, !dev->interrupt_out_busy);
566 		if (retval < 0) {
567 			goto unlock_exit;
568 		}
569 	}
570 
571 	/* write the data into interrupt_out_buffer from userspace */
572 	bytes_to_write = min(count, write_buffer_size*dev->interrupt_out_endpoint_size);
573 	if (bytes_to_write < count)
574 		dev_warn(&dev->intf->dev, "Write buffer overflow, %zd bytes dropped\n",count-bytes_to_write);
575 	dev_dbg(&dev->intf->dev, "%s: count = %zd, bytes_to_write = %zd\n",
576 		__func__, count, bytes_to_write);
577 
578 	if (copy_from_user(dev->interrupt_out_buffer, buffer, bytes_to_write)) {
579 		retval = -EFAULT;
580 		goto unlock_exit;
581 	}
582 
583 	if (dev->interrupt_out_endpoint == NULL) {
584 		/* try HID_REQ_SET_REPORT=9 on control_endpoint instead of interrupt_out_endpoint */
585 		retval = usb_control_msg(interface_to_usbdev(dev->intf),
586 					 usb_sndctrlpipe(interface_to_usbdev(dev->intf), 0),
587 					 9,
588 					 USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_OUT,
589 					 1 << 8, 0,
590 					 dev->interrupt_out_buffer,
591 					 bytes_to_write,
592 					 USB_CTRL_SET_TIMEOUT * HZ);
593 		if (retval < 0)
594 			dev_err(&dev->intf->dev,
595 				"Couldn't submit HID_REQ_SET_REPORT %d\n",
596 				retval);
597 		goto unlock_exit;
598 	}
599 
600 	/* send off the urb */
601 	usb_fill_int_urb(dev->interrupt_out_urb,
602 			 interface_to_usbdev(dev->intf),
603 			 usb_sndintpipe(interface_to_usbdev(dev->intf),
604 					dev->interrupt_out_endpoint->bEndpointAddress),
605 			 dev->interrupt_out_buffer,
606 			 bytes_to_write,
607 			 ld_usb_interrupt_out_callback,
608 			 dev,
609 			 dev->interrupt_out_interval);
610 
611 	dev->interrupt_out_busy = 1;
612 	wmb();
613 
614 	retval = usb_submit_urb(dev->interrupt_out_urb, GFP_KERNEL);
615 	if (retval) {
616 		dev->interrupt_out_busy = 0;
617 		dev_err(&dev->intf->dev,
618 			"Couldn't submit interrupt_out_urb %d\n", retval);
619 		goto unlock_exit;
620 	}
621 	retval = bytes_to_write;
622 
623 unlock_exit:
624 	/* unlock the device */
625 	mutex_unlock(&dev->mutex);
626 
627 exit:
628 	return retval;
629 }
630 
631 /* file operations needed when we register this driver */
632 static const struct file_operations ld_usb_fops = {
633 	.owner =	THIS_MODULE,
634 	.read  =	ld_usb_read,
635 	.write =	ld_usb_write,
636 	.open =		ld_usb_open,
637 	.release =	ld_usb_release,
638 	.poll =		ld_usb_poll,
639 	.llseek =	no_llseek,
640 };
641 
642 /*
643  * usb class driver info in order to get a minor number from the usb core,
644  * and to have the device registered with the driver core
645  */
646 static struct usb_class_driver ld_usb_class = {
647 	.name =		"ldusb%d",
648 	.fops =		&ld_usb_fops,
649 	.minor_base =	USB_LD_MINOR_BASE,
650 };
651 
652 /**
653  *	ld_usb_probe
654  *
655  *	Called by the usb core when a new device is connected that it thinks
656  *	this driver might be interested in.
657  */
658 static int ld_usb_probe(struct usb_interface *intf, const struct usb_device_id *id)
659 {
660 	struct usb_device *udev = interface_to_usbdev(intf);
661 	struct ld_usb *dev = NULL;
662 	struct usb_host_interface *iface_desc;
663 	struct usb_endpoint_descriptor *endpoint;
664 	char *buffer;
665 	int i;
666 	int retval = -ENOMEM;
667 
668 	/* allocate memory for our device state and initialize it */
669 
670 	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
671 	if (dev == NULL) {
672 		dev_err(&intf->dev, "Out of memory\n");
673 		goto exit;
674 	}
675 	mutex_init(&dev->mutex);
676 	spin_lock_init(&dev->rbsl);
677 	dev->intf = intf;
678 	init_waitqueue_head(&dev->read_wait);
679 	init_waitqueue_head(&dev->write_wait);
680 
681 	/* workaround for early firmware versions on fast computers */
682 	if ((le16_to_cpu(udev->descriptor.idVendor) == USB_VENDOR_ID_LD) &&
683 	    ((le16_to_cpu(udev->descriptor.idProduct) == USB_DEVICE_ID_LD_CASSY) ||
684 	     (le16_to_cpu(udev->descriptor.idProduct) == USB_DEVICE_ID_LD_COM3LAB)) &&
685 	    (le16_to_cpu(udev->descriptor.bcdDevice) <= 0x103)) {
686 		buffer = kmalloc(256, GFP_KERNEL);
687 		if (buffer == NULL) {
688 			dev_err(&intf->dev, "Couldn't allocate string buffer\n");
689 			goto error;
690 		}
691 		/* usb_string makes SETUP+STALL to leave always ControlReadLoop */
692 		usb_string(udev, 255, buffer, 256);
693 		kfree(buffer);
694 	}
695 
696 	iface_desc = intf->cur_altsetting;
697 
698 	/* set up the endpoint information */
699 	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
700 		endpoint = &iface_desc->endpoint[i].desc;
701 
702 		if (usb_endpoint_is_int_in(endpoint))
703 			dev->interrupt_in_endpoint = endpoint;
704 
705 		if (usb_endpoint_is_int_out(endpoint))
706 			dev->interrupt_out_endpoint = endpoint;
707 	}
708 	if (dev->interrupt_in_endpoint == NULL) {
709 		dev_err(&intf->dev, "Interrupt in endpoint not found\n");
710 		goto error;
711 	}
712 	if (dev->interrupt_out_endpoint == NULL)
713 		dev_warn(&intf->dev, "Interrupt out endpoint not found (using control endpoint instead)\n");
714 
715 	dev->interrupt_in_endpoint_size = usb_endpoint_maxp(dev->interrupt_in_endpoint);
716 	dev->ring_buffer = kmalloc(ring_buffer_size*(sizeof(size_t)+dev->interrupt_in_endpoint_size), GFP_KERNEL);
717 	if (!dev->ring_buffer) {
718 		dev_err(&intf->dev, "Couldn't allocate ring_buffer\n");
719 		goto error;
720 	}
721 	dev->interrupt_in_buffer = kmalloc(dev->interrupt_in_endpoint_size, GFP_KERNEL);
722 	if (!dev->interrupt_in_buffer) {
723 		dev_err(&intf->dev, "Couldn't allocate interrupt_in_buffer\n");
724 		goto error;
725 	}
726 	dev->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
727 	if (!dev->interrupt_in_urb) {
728 		dev_err(&intf->dev, "Couldn't allocate interrupt_in_urb\n");
729 		goto error;
730 	}
731 	dev->interrupt_out_endpoint_size = dev->interrupt_out_endpoint ? usb_endpoint_maxp(dev->interrupt_out_endpoint) :
732 									 udev->descriptor.bMaxPacketSize0;
733 	dev->interrupt_out_buffer = kmalloc(write_buffer_size*dev->interrupt_out_endpoint_size, GFP_KERNEL);
734 	if (!dev->interrupt_out_buffer) {
735 		dev_err(&intf->dev, "Couldn't allocate interrupt_out_buffer\n");
736 		goto error;
737 	}
738 	dev->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
739 	if (!dev->interrupt_out_urb) {
740 		dev_err(&intf->dev, "Couldn't allocate interrupt_out_urb\n");
741 		goto error;
742 	}
743 	dev->interrupt_in_interval = min_interrupt_in_interval > dev->interrupt_in_endpoint->bInterval ? min_interrupt_in_interval : dev->interrupt_in_endpoint->bInterval;
744 	if (dev->interrupt_out_endpoint)
745 		dev->interrupt_out_interval = min_interrupt_out_interval > dev->interrupt_out_endpoint->bInterval ? min_interrupt_out_interval : dev->interrupt_out_endpoint->bInterval;
746 
747 	/* we can register the device now, as it is ready */
748 	usb_set_intfdata(intf, dev);
749 
750 	retval = usb_register_dev(intf, &ld_usb_class);
751 	if (retval) {
752 		/* something prevented us from registering this driver */
753 		dev_err(&intf->dev, "Not able to get a minor for this device.\n");
754 		usb_set_intfdata(intf, NULL);
755 		goto error;
756 	}
757 
758 	/* let the user know what node this device is now attached to */
759 	dev_info(&intf->dev, "LD USB Device #%d now attached to major %d minor %d\n",
760 		(intf->minor - USB_LD_MINOR_BASE), USB_MAJOR, intf->minor);
761 
762 exit:
763 	return retval;
764 
765 error:
766 	ld_usb_delete(dev);
767 
768 	return retval;
769 }
770 
771 /**
772  *	ld_usb_disconnect
773  *
774  *	Called by the usb core when the device is removed from the system.
775  */
776 static void ld_usb_disconnect(struct usb_interface *intf)
777 {
778 	struct ld_usb *dev;
779 	int minor;
780 
781 	dev = usb_get_intfdata(intf);
782 	usb_set_intfdata(intf, NULL);
783 
784 	minor = intf->minor;
785 
786 	/* give back our minor */
787 	usb_deregister_dev(intf, &ld_usb_class);
788 
789 	mutex_lock(&dev->mutex);
790 
791 	/* if the device is not opened, then we clean up right now */
792 	if (!dev->open_count) {
793 		mutex_unlock(&dev->mutex);
794 		ld_usb_delete(dev);
795 	} else {
796 		dev->intf = NULL;
797 		/* wake up pollers */
798 		wake_up_interruptible_all(&dev->read_wait);
799 		wake_up_interruptible_all(&dev->write_wait);
800 		mutex_unlock(&dev->mutex);
801 	}
802 
803 	dev_info(&intf->dev, "LD USB Device #%d now disconnected\n",
804 		 (minor - USB_LD_MINOR_BASE));
805 }
806 
807 /* usb specific object needed to register this driver with the usb subsystem */
808 static struct usb_driver ld_usb_driver = {
809 	.name =		"ldusb",
810 	.probe =	ld_usb_probe,
811 	.disconnect =	ld_usb_disconnect,
812 	.id_table =	ld_usb_table,
813 };
814 
815 module_usb_driver(ld_usb_driver);
816 
817