xref: /openbmc/linux/drivers/usb/misc/ldusb.c (revision 8730046c)
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 <linux/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 #ifdef CONFIG_USB_DYNAMIC_MINORS
73 #define USB_LD_MINOR_BASE	0
74 #else
75 #define USB_LD_MINOR_BASE	176
76 #endif
77 
78 /* table of devices that work with this driver */
79 static const struct usb_device_id ld_usb_table[] = {
80 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_CASSY) },
81 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_CASSY2) },
82 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_POCKETCASSY) },
83 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_POCKETCASSY2) },
84 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MOBILECASSY) },
85 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MOBILECASSY2) },
86 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MICROCASSYVOLTAGE) },
87 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MICROCASSYCURRENT) },
88 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MICROCASSYTIME) },
89 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MICROCASSYTEMPERATURE) },
90 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MICROCASSYPH) },
91 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_JWM) },
92 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_DMMP) },
93 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_UMIP) },
94 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_UMIC) },
95 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_UMIB) },
96 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_XRAY) },
97 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_XRAY2) },
98 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_VIDEOCOM) },
99 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MOTOR) },
100 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_COM3LAB) },
101 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_TELEPORT) },
102 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_NETWORKANALYSER) },
103 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_POWERCONTROL) },
104 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MACHINETEST) },
105 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MOSTANALYSER) },
106 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MOSTANALYSER2) },
107 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_ABSESP) },
108 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_AUTODATABUS) },
109 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MCT) },
110 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_HYBRID) },
111 	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_HEATCONTROL) },
112 	{ }					/* Terminating entry */
113 };
114 MODULE_DEVICE_TABLE(usb, ld_usb_table);
115 MODULE_VERSION("V0.14");
116 MODULE_AUTHOR("Michael Hund <mhund@ld-didactic.de>");
117 MODULE_DESCRIPTION("LD USB Driver");
118 MODULE_LICENSE("GPL");
119 MODULE_SUPPORTED_DEVICE("LD USB Devices");
120 
121 /* All interrupt in transfers are collected in a ring buffer to
122  * avoid racing conditions and get better performance of the driver.
123  */
124 static int ring_buffer_size = 128;
125 module_param(ring_buffer_size, int, 0);
126 MODULE_PARM_DESC(ring_buffer_size, "Read ring buffer size in reports");
127 
128 /* The write_buffer can contain more than one interrupt out transfer.
129  */
130 static int write_buffer_size = 10;
131 module_param(write_buffer_size, int, 0);
132 MODULE_PARM_DESC(write_buffer_size, "Write buffer size in reports");
133 
134 /* As of kernel version 2.6.4 ehci-hcd uses an
135  * "only one interrupt transfer per frame" shortcut
136  * to simplify the scheduling of periodic transfers.
137  * This conflicts with our standard 1ms intervals for in and out URBs.
138  * We use default intervals of 2ms for in and 2ms for out transfers,
139  * which should be fast enough.
140  * Increase the interval to allow more devices that do interrupt transfers,
141  * or set to 1 to use the standard interval from the endpoint descriptors.
142  */
143 static int min_interrupt_in_interval = 2;
144 module_param(min_interrupt_in_interval, int, 0);
145 MODULE_PARM_DESC(min_interrupt_in_interval, "Minimum interrupt in interval in ms");
146 
147 static int min_interrupt_out_interval = 2;
148 module_param(min_interrupt_out_interval, int, 0);
149 MODULE_PARM_DESC(min_interrupt_out_interval, "Minimum interrupt out interval in ms");
150 
151 /* Structure to hold all of our device specific stuff */
152 struct ld_usb {
153 	struct mutex		mutex;		/* locks this structure */
154 	struct usb_interface*	intf;		/* save off the usb interface pointer */
155 
156 	int			open_count;	/* number of times this port has been opened */
157 
158 	char*			ring_buffer;
159 	unsigned int		ring_head;
160 	unsigned int		ring_tail;
161 
162 	wait_queue_head_t	read_wait;
163 	wait_queue_head_t	write_wait;
164 
165 	char*			interrupt_in_buffer;
166 	struct usb_endpoint_descriptor* interrupt_in_endpoint;
167 	struct urb*		interrupt_in_urb;
168 	int			interrupt_in_interval;
169 	size_t			interrupt_in_endpoint_size;
170 	int			interrupt_in_running;
171 	int			interrupt_in_done;
172 	int			buffer_overflow;
173 	spinlock_t		rbsl;
174 
175 	char*			interrupt_out_buffer;
176 	struct usb_endpoint_descriptor* interrupt_out_endpoint;
177 	struct urb*		interrupt_out_urb;
178 	int			interrupt_out_interval;
179 	size_t			interrupt_out_endpoint_size;
180 	int			interrupt_out_busy;
181 };
182 
183 static struct usb_driver ld_usb_driver;
184 
185 /**
186  *	ld_usb_abort_transfers
187  *      aborts transfers and frees associated data structures
188  */
189 static void ld_usb_abort_transfers(struct ld_usb *dev)
190 {
191 	/* shutdown transfer */
192 	if (dev->interrupt_in_running) {
193 		dev->interrupt_in_running = 0;
194 		if (dev->intf)
195 			usb_kill_urb(dev->interrupt_in_urb);
196 	}
197 	if (dev->interrupt_out_busy)
198 		if (dev->intf)
199 			usb_kill_urb(dev->interrupt_out_urb);
200 }
201 
202 /**
203  *	ld_usb_delete
204  */
205 static void ld_usb_delete(struct ld_usb *dev)
206 {
207 	ld_usb_abort_transfers(dev);
208 
209 	/* free data structures */
210 	usb_free_urb(dev->interrupt_in_urb);
211 	usb_free_urb(dev->interrupt_out_urb);
212 	kfree(dev->ring_buffer);
213 	kfree(dev->interrupt_in_buffer);
214 	kfree(dev->interrupt_out_buffer);
215 	kfree(dev);
216 }
217 
218 /**
219  *	ld_usb_interrupt_in_callback
220  */
221 static void ld_usb_interrupt_in_callback(struct urb *urb)
222 {
223 	struct ld_usb *dev = urb->context;
224 	size_t *actual_buffer;
225 	unsigned int next_ring_head;
226 	int status = urb->status;
227 	int retval;
228 
229 	if (status) {
230 		if (status == -ENOENT ||
231 		    status == -ECONNRESET ||
232 		    status == -ESHUTDOWN) {
233 			goto exit;
234 		} else {
235 			dev_dbg(&dev->intf->dev,
236 				"%s: nonzero status received: %d\n", __func__,
237 				status);
238 			spin_lock(&dev->rbsl);
239 			goto resubmit; /* maybe we can recover */
240 		}
241 	}
242 
243 	spin_lock(&dev->rbsl);
244 	if (urb->actual_length > 0) {
245 		next_ring_head = (dev->ring_head+1) % ring_buffer_size;
246 		if (next_ring_head != dev->ring_tail) {
247 			actual_buffer = (size_t*)(dev->ring_buffer + dev->ring_head*(sizeof(size_t)+dev->interrupt_in_endpoint_size));
248 			/* actual_buffer gets urb->actual_length + interrupt_in_buffer */
249 			*actual_buffer = urb->actual_length;
250 			memcpy(actual_buffer+1, dev->interrupt_in_buffer, urb->actual_length);
251 			dev->ring_head = next_ring_head;
252 			dev_dbg(&dev->intf->dev, "%s: received %d bytes\n",
253 				__func__, urb->actual_length);
254 		} else {
255 			dev_warn(&dev->intf->dev,
256 				 "Ring buffer overflow, %d bytes dropped\n",
257 				 urb->actual_length);
258 			dev->buffer_overflow = 1;
259 		}
260 	}
261 
262 resubmit:
263 	/* resubmit if we're still running */
264 	if (dev->interrupt_in_running && !dev->buffer_overflow && dev->intf) {
265 		retval = usb_submit_urb(dev->interrupt_in_urb, GFP_ATOMIC);
266 		if (retval) {
267 			dev_err(&dev->intf->dev,
268 				"usb_submit_urb failed (%d)\n", retval);
269 			dev->buffer_overflow = 1;
270 		}
271 	}
272 	spin_unlock(&dev->rbsl);
273 exit:
274 	dev->interrupt_in_done = 1;
275 	wake_up_interruptible(&dev->read_wait);
276 }
277 
278 /**
279  *	ld_usb_interrupt_out_callback
280  */
281 static void ld_usb_interrupt_out_callback(struct urb *urb)
282 {
283 	struct ld_usb *dev = urb->context;
284 	int status = urb->status;
285 
286 	/* sync/async unlink faults aren't errors */
287 	if (status && !(status == -ENOENT ||
288 			status == -ECONNRESET ||
289 			status == -ESHUTDOWN))
290 		dev_dbg(&dev->intf->dev,
291 			"%s - nonzero write interrupt status received: %d\n",
292 			__func__, status);
293 
294 	dev->interrupt_out_busy = 0;
295 	wake_up_interruptible(&dev->write_wait);
296 }
297 
298 /**
299  *	ld_usb_open
300  */
301 static int ld_usb_open(struct inode *inode, struct file *file)
302 {
303 	struct ld_usb *dev;
304 	int subminor;
305 	int retval;
306 	struct usb_interface *interface;
307 
308 	nonseekable_open(inode, file);
309 	subminor = iminor(inode);
310 
311 	interface = usb_find_interface(&ld_usb_driver, subminor);
312 
313 	if (!interface) {
314 		printk(KERN_ERR "%s - error, can't find device for minor %d\n",
315 		       __func__, subminor);
316 		return -ENODEV;
317 	}
318 
319 	dev = usb_get_intfdata(interface);
320 
321 	if (!dev)
322 		return -ENODEV;
323 
324 	/* lock this device */
325 	if (mutex_lock_interruptible(&dev->mutex))
326 		return -ERESTARTSYS;
327 
328 	/* allow opening only once */
329 	if (dev->open_count) {
330 		retval = -EBUSY;
331 		goto unlock_exit;
332 	}
333 	dev->open_count = 1;
334 
335 	/* initialize in direction */
336 	dev->ring_head = 0;
337 	dev->ring_tail = 0;
338 	dev->buffer_overflow = 0;
339 	usb_fill_int_urb(dev->interrupt_in_urb,
340 			 interface_to_usbdev(interface),
341 			 usb_rcvintpipe(interface_to_usbdev(interface),
342 					dev->interrupt_in_endpoint->bEndpointAddress),
343 			 dev->interrupt_in_buffer,
344 			 dev->interrupt_in_endpoint_size,
345 			 ld_usb_interrupt_in_callback,
346 			 dev,
347 			 dev->interrupt_in_interval);
348 
349 	dev->interrupt_in_running = 1;
350 	dev->interrupt_in_done = 0;
351 
352 	retval = usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
353 	if (retval) {
354 		dev_err(&interface->dev, "Couldn't submit interrupt_in_urb %d\n", retval);
355 		dev->interrupt_in_running = 0;
356 		dev->open_count = 0;
357 		goto unlock_exit;
358 	}
359 
360 	/* save device in the file's private structure */
361 	file->private_data = dev;
362 
363 unlock_exit:
364 	mutex_unlock(&dev->mutex);
365 
366 	return retval;
367 }
368 
369 /**
370  *	ld_usb_release
371  */
372 static int ld_usb_release(struct inode *inode, struct file *file)
373 {
374 	struct ld_usb *dev;
375 	int retval = 0;
376 
377 	dev = file->private_data;
378 
379 	if (dev == NULL) {
380 		retval = -ENODEV;
381 		goto exit;
382 	}
383 
384 	if (mutex_lock_interruptible(&dev->mutex)) {
385 		retval = -ERESTARTSYS;
386 		goto exit;
387 	}
388 
389 	if (dev->open_count != 1) {
390 		retval = -ENODEV;
391 		goto unlock_exit;
392 	}
393 	if (dev->intf == NULL) {
394 		/* the device was unplugged before the file was released */
395 		mutex_unlock(&dev->mutex);
396 		/* unlock here as ld_usb_delete frees dev */
397 		ld_usb_delete(dev);
398 		goto exit;
399 	}
400 
401 	/* wait until write transfer is finished */
402 	if (dev->interrupt_out_busy)
403 		wait_event_interruptible_timeout(dev->write_wait, !dev->interrupt_out_busy, 2 * HZ);
404 	ld_usb_abort_transfers(dev);
405 	dev->open_count = 0;
406 
407 unlock_exit:
408 	mutex_unlock(&dev->mutex);
409 
410 exit:
411 	return retval;
412 }
413 
414 /**
415  *	ld_usb_poll
416  */
417 static unsigned int ld_usb_poll(struct file *file, poll_table *wait)
418 {
419 	struct ld_usb *dev;
420 	unsigned int mask = 0;
421 
422 	dev = file->private_data;
423 
424 	if (!dev->intf)
425 		return POLLERR | POLLHUP;
426 
427 	poll_wait(file, &dev->read_wait, wait);
428 	poll_wait(file, &dev->write_wait, wait);
429 
430 	if (dev->ring_head != dev->ring_tail)
431 		mask |= POLLIN | POLLRDNORM;
432 	if (!dev->interrupt_out_busy)
433 		mask |= POLLOUT | POLLWRNORM;
434 
435 	return mask;
436 }
437 
438 /**
439  *	ld_usb_read
440  */
441 static ssize_t ld_usb_read(struct file *file, char __user *buffer, size_t count,
442 			   loff_t *ppos)
443 {
444 	struct ld_usb *dev;
445 	size_t *actual_buffer;
446 	size_t bytes_to_read;
447 	int retval = 0;
448 	int rv;
449 
450 	dev = file->private_data;
451 
452 	/* verify that we actually have some data to read */
453 	if (count == 0)
454 		goto exit;
455 
456 	/* lock this object */
457 	if (mutex_lock_interruptible(&dev->mutex)) {
458 		retval = -ERESTARTSYS;
459 		goto exit;
460 	}
461 
462 	/* verify that the device wasn't unplugged */
463 	if (dev->intf == NULL) {
464 		retval = -ENODEV;
465 		printk(KERN_ERR "ldusb: No device or device unplugged %d\n", retval);
466 		goto unlock_exit;
467 	}
468 
469 	/* wait for data */
470 	spin_lock_irq(&dev->rbsl);
471 	if (dev->ring_head == dev->ring_tail) {
472 		dev->interrupt_in_done = 0;
473 		spin_unlock_irq(&dev->rbsl);
474 		if (file->f_flags & O_NONBLOCK) {
475 			retval = -EAGAIN;
476 			goto unlock_exit;
477 		}
478 		retval = wait_event_interruptible(dev->read_wait, dev->interrupt_in_done);
479 		if (retval < 0)
480 			goto unlock_exit;
481 	} else {
482 		spin_unlock_irq(&dev->rbsl);
483 	}
484 
485 	/* actual_buffer contains actual_length + interrupt_in_buffer */
486 	actual_buffer = (size_t*)(dev->ring_buffer + dev->ring_tail*(sizeof(size_t)+dev->interrupt_in_endpoint_size));
487 	bytes_to_read = min(count, *actual_buffer);
488 	if (bytes_to_read < *actual_buffer)
489 		dev_warn(&dev->intf->dev, "Read buffer overflow, %zd bytes dropped\n",
490 			 *actual_buffer-bytes_to_read);
491 
492 	/* copy one interrupt_in_buffer from ring_buffer into userspace */
493 	if (copy_to_user(buffer, actual_buffer+1, bytes_to_read)) {
494 		retval = -EFAULT;
495 		goto unlock_exit;
496 	}
497 	dev->ring_tail = (dev->ring_tail+1) % ring_buffer_size;
498 
499 	retval = bytes_to_read;
500 
501 	spin_lock_irq(&dev->rbsl);
502 	if (dev->buffer_overflow) {
503 		dev->buffer_overflow = 0;
504 		spin_unlock_irq(&dev->rbsl);
505 		rv = usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
506 		if (rv < 0)
507 			dev->buffer_overflow = 1;
508 	} else {
509 		spin_unlock_irq(&dev->rbsl);
510 	}
511 
512 unlock_exit:
513 	/* unlock the device */
514 	mutex_unlock(&dev->mutex);
515 
516 exit:
517 	return retval;
518 }
519 
520 /**
521  *	ld_usb_write
522  */
523 static ssize_t ld_usb_write(struct file *file, const char __user *buffer,
524 			    size_t count, loff_t *ppos)
525 {
526 	struct ld_usb *dev;
527 	size_t bytes_to_write;
528 	int retval = 0;
529 
530 	dev = file->private_data;
531 
532 	/* verify that we actually have some data to write */
533 	if (count == 0)
534 		goto exit;
535 
536 	/* lock this object */
537 	if (mutex_lock_interruptible(&dev->mutex)) {
538 		retval = -ERESTARTSYS;
539 		goto exit;
540 	}
541 
542 	/* verify that the device wasn't unplugged */
543 	if (dev->intf == NULL) {
544 		retval = -ENODEV;
545 		printk(KERN_ERR "ldusb: No device or device unplugged %d\n", retval);
546 		goto unlock_exit;
547 	}
548 
549 	/* wait until previous transfer is finished */
550 	if (dev->interrupt_out_busy) {
551 		if (file->f_flags & O_NONBLOCK) {
552 			retval = -EAGAIN;
553 			goto unlock_exit;
554 		}
555 		retval = wait_event_interruptible(dev->write_wait, !dev->interrupt_out_busy);
556 		if (retval < 0) {
557 			goto unlock_exit;
558 		}
559 	}
560 
561 	/* write the data into interrupt_out_buffer from userspace */
562 	bytes_to_write = min(count, write_buffer_size*dev->interrupt_out_endpoint_size);
563 	if (bytes_to_write < count)
564 		dev_warn(&dev->intf->dev, "Write buffer overflow, %zd bytes dropped\n",count-bytes_to_write);
565 	dev_dbg(&dev->intf->dev, "%s: count = %zd, bytes_to_write = %zd\n",
566 		__func__, count, bytes_to_write);
567 
568 	if (copy_from_user(dev->interrupt_out_buffer, buffer, bytes_to_write)) {
569 		retval = -EFAULT;
570 		goto unlock_exit;
571 	}
572 
573 	if (dev->interrupt_out_endpoint == NULL) {
574 		/* try HID_REQ_SET_REPORT=9 on control_endpoint instead of interrupt_out_endpoint */
575 		retval = usb_control_msg(interface_to_usbdev(dev->intf),
576 					 usb_sndctrlpipe(interface_to_usbdev(dev->intf), 0),
577 					 9,
578 					 USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_OUT,
579 					 1 << 8, 0,
580 					 dev->interrupt_out_buffer,
581 					 bytes_to_write,
582 					 USB_CTRL_SET_TIMEOUT * HZ);
583 		if (retval < 0)
584 			dev_err(&dev->intf->dev,
585 				"Couldn't submit HID_REQ_SET_REPORT %d\n",
586 				retval);
587 		goto unlock_exit;
588 	}
589 
590 	/* send off the urb */
591 	usb_fill_int_urb(dev->interrupt_out_urb,
592 			 interface_to_usbdev(dev->intf),
593 			 usb_sndintpipe(interface_to_usbdev(dev->intf),
594 					dev->interrupt_out_endpoint->bEndpointAddress),
595 			 dev->interrupt_out_buffer,
596 			 bytes_to_write,
597 			 ld_usb_interrupt_out_callback,
598 			 dev,
599 			 dev->interrupt_out_interval);
600 
601 	dev->interrupt_out_busy = 1;
602 	wmb();
603 
604 	retval = usb_submit_urb(dev->interrupt_out_urb, GFP_KERNEL);
605 	if (retval) {
606 		dev->interrupt_out_busy = 0;
607 		dev_err(&dev->intf->dev,
608 			"Couldn't submit interrupt_out_urb %d\n", retval);
609 		goto unlock_exit;
610 	}
611 	retval = bytes_to_write;
612 
613 unlock_exit:
614 	/* unlock the device */
615 	mutex_unlock(&dev->mutex);
616 
617 exit:
618 	return retval;
619 }
620 
621 /* file operations needed when we register this driver */
622 static const struct file_operations ld_usb_fops = {
623 	.owner =	THIS_MODULE,
624 	.read  =	ld_usb_read,
625 	.write =	ld_usb_write,
626 	.open =		ld_usb_open,
627 	.release =	ld_usb_release,
628 	.poll =		ld_usb_poll,
629 	.llseek =	no_llseek,
630 };
631 
632 /*
633  * usb class driver info in order to get a minor number from the usb core,
634  * and to have the device registered with the driver core
635  */
636 static struct usb_class_driver ld_usb_class = {
637 	.name =		"ldusb%d",
638 	.fops =		&ld_usb_fops,
639 	.minor_base =	USB_LD_MINOR_BASE,
640 };
641 
642 /**
643  *	ld_usb_probe
644  *
645  *	Called by the usb core when a new device is connected that it thinks
646  *	this driver might be interested in.
647  */
648 static int ld_usb_probe(struct usb_interface *intf, const struct usb_device_id *id)
649 {
650 	struct usb_device *udev = interface_to_usbdev(intf);
651 	struct ld_usb *dev = NULL;
652 	struct usb_host_interface *iface_desc;
653 	struct usb_endpoint_descriptor *endpoint;
654 	char *buffer;
655 	int i;
656 	int retval = -ENOMEM;
657 
658 	/* allocate memory for our device state and initialize it */
659 
660 	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
661 	if (!dev)
662 		goto exit;
663 	mutex_init(&dev->mutex);
664 	spin_lock_init(&dev->rbsl);
665 	dev->intf = intf;
666 	init_waitqueue_head(&dev->read_wait);
667 	init_waitqueue_head(&dev->write_wait);
668 
669 	/* workaround for early firmware versions on fast computers */
670 	if ((le16_to_cpu(udev->descriptor.idVendor) == USB_VENDOR_ID_LD) &&
671 	    ((le16_to_cpu(udev->descriptor.idProduct) == USB_DEVICE_ID_LD_CASSY) ||
672 	     (le16_to_cpu(udev->descriptor.idProduct) == USB_DEVICE_ID_LD_COM3LAB)) &&
673 	    (le16_to_cpu(udev->descriptor.bcdDevice) <= 0x103)) {
674 		buffer = kmalloc(256, GFP_KERNEL);
675 		if (!buffer)
676 			goto error;
677 		/* usb_string makes SETUP+STALL to leave always ControlReadLoop */
678 		usb_string(udev, 255, buffer, 256);
679 		kfree(buffer);
680 	}
681 
682 	iface_desc = intf->cur_altsetting;
683 
684 	/* set up the endpoint information */
685 	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
686 		endpoint = &iface_desc->endpoint[i].desc;
687 
688 		if (usb_endpoint_is_int_in(endpoint))
689 			dev->interrupt_in_endpoint = endpoint;
690 
691 		if (usb_endpoint_is_int_out(endpoint))
692 			dev->interrupt_out_endpoint = endpoint;
693 	}
694 	if (dev->interrupt_in_endpoint == NULL) {
695 		dev_err(&intf->dev, "Interrupt in endpoint not found\n");
696 		goto error;
697 	}
698 	if (dev->interrupt_out_endpoint == NULL)
699 		dev_warn(&intf->dev, "Interrupt out endpoint not found (using control endpoint instead)\n");
700 
701 	dev->interrupt_in_endpoint_size = usb_endpoint_maxp(dev->interrupt_in_endpoint);
702 	dev->ring_buffer = kmalloc(ring_buffer_size*(sizeof(size_t)+dev->interrupt_in_endpoint_size), GFP_KERNEL);
703 	if (!dev->ring_buffer)
704 		goto error;
705 	dev->interrupt_in_buffer = kmalloc(dev->interrupt_in_endpoint_size, GFP_KERNEL);
706 	if (!dev->interrupt_in_buffer)
707 		goto error;
708 	dev->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
709 	if (!dev->interrupt_in_urb)
710 		goto error;
711 	dev->interrupt_out_endpoint_size = dev->interrupt_out_endpoint ? usb_endpoint_maxp(dev->interrupt_out_endpoint) :
712 									 udev->descriptor.bMaxPacketSize0;
713 	dev->interrupt_out_buffer = kmalloc(write_buffer_size*dev->interrupt_out_endpoint_size, GFP_KERNEL);
714 	if (!dev->interrupt_out_buffer)
715 		goto error;
716 	dev->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
717 	if (!dev->interrupt_out_urb)
718 		goto error;
719 	dev->interrupt_in_interval = min_interrupt_in_interval > dev->interrupt_in_endpoint->bInterval ? min_interrupt_in_interval : dev->interrupt_in_endpoint->bInterval;
720 	if (dev->interrupt_out_endpoint)
721 		dev->interrupt_out_interval = min_interrupt_out_interval > dev->interrupt_out_endpoint->bInterval ? min_interrupt_out_interval : dev->interrupt_out_endpoint->bInterval;
722 
723 	/* we can register the device now, as it is ready */
724 	usb_set_intfdata(intf, dev);
725 
726 	retval = usb_register_dev(intf, &ld_usb_class);
727 	if (retval) {
728 		/* something prevented us from registering this driver */
729 		dev_err(&intf->dev, "Not able to get a minor for this device.\n");
730 		usb_set_intfdata(intf, NULL);
731 		goto error;
732 	}
733 
734 	/* let the user know what node this device is now attached to */
735 	dev_info(&intf->dev, "LD USB Device #%d now attached to major %d minor %d\n",
736 		(intf->minor - USB_LD_MINOR_BASE), USB_MAJOR, intf->minor);
737 
738 exit:
739 	return retval;
740 
741 error:
742 	ld_usb_delete(dev);
743 
744 	return retval;
745 }
746 
747 /**
748  *	ld_usb_disconnect
749  *
750  *	Called by the usb core when the device is removed from the system.
751  */
752 static void ld_usb_disconnect(struct usb_interface *intf)
753 {
754 	struct ld_usb *dev;
755 	int minor;
756 
757 	dev = usb_get_intfdata(intf);
758 	usb_set_intfdata(intf, NULL);
759 
760 	minor = intf->minor;
761 
762 	/* give back our minor */
763 	usb_deregister_dev(intf, &ld_usb_class);
764 
765 	mutex_lock(&dev->mutex);
766 
767 	/* if the device is not opened, then we clean up right now */
768 	if (!dev->open_count) {
769 		mutex_unlock(&dev->mutex);
770 		ld_usb_delete(dev);
771 	} else {
772 		dev->intf = NULL;
773 		/* wake up pollers */
774 		wake_up_interruptible_all(&dev->read_wait);
775 		wake_up_interruptible_all(&dev->write_wait);
776 		mutex_unlock(&dev->mutex);
777 	}
778 
779 	dev_info(&intf->dev, "LD USB Device #%d now disconnected\n",
780 		 (minor - USB_LD_MINOR_BASE));
781 }
782 
783 /* usb specific object needed to register this driver with the usb subsystem */
784 static struct usb_driver ld_usb_driver = {
785 	.name =		"ldusb",
786 	.probe =	ld_usb_probe,
787 	.disconnect =	ld_usb_disconnect,
788 	.id_table =	ld_usb_table,
789 };
790 
791 module_usb_driver(ld_usb_driver);
792 
793