xref: /linux/drivers/usb/core/devices.c (revision a17627ef8833ac30622a7b39b7be390e1b174405)
1 /*
2  * devices.c
3  * (C) Copyright 1999 Randy Dunlap.
4  * (C) Copyright 1999,2000 Thomas Sailer <sailer@ife.ee.ethz.ch>. (proc file per device)
5  * (C) Copyright 1999 Deti Fliegl (new USB architecture)
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License as published by
9  * the Free Software Foundation; either version 2 of the License, or
10  * (at your option) any later version.
11  *
12  * This program is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  * GNU General Public License for more details.
16  *
17  * You should have received a copy of the GNU General Public License
18  * along with this program; if not, write to the Free Software
19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
20  *
21  *************************************************************
22  *
23  * <mountpoint>/devices contains USB topology, device, config, class,
24  * interface, & endpoint data.
25  *
26  * I considered using /proc/bus/usb/devices/device# for each device
27  * as it is attached or detached, but I didn't like this for some
28  * reason -- maybe it's just too deep of a directory structure.
29  * I also don't like looking in multiple places to gather and view
30  * the data.  Having only one file for ./devices also prevents race
31  * conditions that could arise if a program was reading device info
32  * for devices that are being removed (unplugged).  (That is, the
33  * program may find a directory for devnum_12 then try to open it,
34  * but it was just unplugged, so the directory is now deleted.
35  * But programs would just have to be prepared for situations like
36  * this in any plug-and-play environment.)
37  *
38  * 1999-12-16: Thomas Sailer <sailer@ife.ee.ethz.ch>
39  *   Converted the whole proc stuff to real
40  *   read methods. Now not the whole device list needs to fit
41  *   into one page, only the device list for one bus.
42  *   Added a poll method to /proc/bus/usb/devices, to wake
43  *   up an eventual usbd
44  * 2000-01-04: Thomas Sailer <sailer@ife.ee.ethz.ch>
45  *   Turned into its own filesystem
46  * 2000-07-05: Ashley Montanaro <ashley@compsoc.man.ac.uk>
47  *   Converted file reading routine to dump to buffer once
48  *   per device, not per bus
49  *
50  * $Id: devices.c,v 1.5 2000/01/11 13:58:21 tom Exp $
51  */
52 
53 #include <linux/fs.h>
54 #include <linux/mm.h>
55 #include <linux/slab.h>
56 #include <linux/poll.h>
57 #include <linux/usb.h>
58 #include <linux/smp_lock.h>
59 #include <linux/usbdevice_fs.h>
60 #include <linux/mutex.h>
61 #include <asm/uaccess.h>
62 
63 #include "usb.h"
64 #include "hcd.h"
65 
66 #define MAX_TOPO_LEVEL		6
67 
68 /* Define ALLOW_SERIAL_NUMBER if you want to see the serial number of devices */
69 #define ALLOW_SERIAL_NUMBER
70 
71 static const char *format_topo =
72 /* T:  Bus=dd Lev=dd Prnt=dd Port=dd Cnt=dd Dev#=ddd Spd=ddd MxCh=dd */
73 "\nT:  Bus=%2.2d Lev=%2.2d Prnt=%2.2d Port=%2.2d Cnt=%2.2d Dev#=%3d Spd=%3s MxCh=%2d\n";
74 
75 static const char *format_string_manufacturer =
76 /* S:  Manufacturer=xxxx */
77   "S:  Manufacturer=%.100s\n";
78 
79 static const char *format_string_product =
80 /* S:  Product=xxxx */
81   "S:  Product=%.100s\n";
82 
83 #ifdef ALLOW_SERIAL_NUMBER
84 static const char *format_string_serialnumber =
85 /* S:  SerialNumber=xxxx */
86   "S:  SerialNumber=%.100s\n";
87 #endif
88 
89 static const char *format_bandwidth =
90 /* B:  Alloc=ddd/ddd us (xx%), #Int=ddd, #Iso=ddd */
91   "B:  Alloc=%3d/%3d us (%2d%%), #Int=%3d, #Iso=%3d\n";
92 
93 static const char *format_device1 =
94 /* D:  Ver=xx.xx Cls=xx(sssss) Sub=xx Prot=xx MxPS=dd #Cfgs=dd */
95   "D:  Ver=%2x.%02x Cls=%02x(%-5s) Sub=%02x Prot=%02x MxPS=%2d #Cfgs=%3d\n";
96 
97 static const char *format_device2 =
98 /* P:  Vendor=xxxx ProdID=xxxx Rev=xx.xx */
99   "P:  Vendor=%04x ProdID=%04x Rev=%2x.%02x\n";
100 
101 static const char *format_config =
102 /* C:  #Ifs=dd Cfg#=dd Atr=xx MPwr=dddmA */
103   "C:%c #Ifs=%2d Cfg#=%2d Atr=%02x MxPwr=%3dmA\n";
104 
105 static const char *format_iface =
106 /* I:  If#=dd Alt=dd #EPs=dd Cls=xx(sssss) Sub=xx Prot=xx Driver=xxxx*/
107   "I:%c If#=%2d Alt=%2d #EPs=%2d Cls=%02x(%-5s) Sub=%02x Prot=%02x Driver=%s\n";
108 
109 static const char *format_endpt =
110 /* E:  Ad=xx(s) Atr=xx(ssss) MxPS=dddd Ivl=D?s */
111   "E:  Ad=%02x(%c) Atr=%02x(%-4s) MxPS=%4d Ivl=%d%cs\n";
112 
113 
114 /*
115  * Need access to the driver and USB bus lists.
116  * extern struct list_head usb_bus_list;
117  * However, these will come from functions that return ptrs to each of them.
118  */
119 
120 static DECLARE_WAIT_QUEUE_HEAD(deviceconndiscwq);
121 static unsigned int conndiscevcnt = 0;
122 
123 /* this struct stores the poll state for <mountpoint>/devices pollers */
124 struct usb_device_status {
125 	unsigned int lastev;
126 };
127 
128 struct class_info {
129 	int class;
130 	char *class_name;
131 };
132 
133 static const struct class_info clas_info[] =
134 {					/* max. 5 chars. per name string */
135 	{USB_CLASS_PER_INTERFACE,	">ifc"},
136 	{USB_CLASS_AUDIO,		"audio"},
137 	{USB_CLASS_COMM,		"comm."},
138 	{USB_CLASS_HID,			"HID"},
139 	{USB_CLASS_HUB,			"hub"},
140 	{USB_CLASS_PHYSICAL,		"PID"},
141 	{USB_CLASS_PRINTER,		"print"},
142 	{USB_CLASS_MASS_STORAGE,	"stor."},
143 	{USB_CLASS_CDC_DATA,		"data"},
144 	{USB_CLASS_APP_SPEC,		"app."},
145 	{USB_CLASS_VENDOR_SPEC,		"vend."},
146 	{USB_CLASS_STILL_IMAGE,		"still"},
147 	{USB_CLASS_CSCID,		"scard"},
148 	{USB_CLASS_CONTENT_SEC,		"c-sec"},
149 	{-1,				"unk."}		/* leave as last */
150 };
151 
152 /*****************************************************************/
153 
154 void usbfs_conn_disc_event(void)
155 {
156 	conndiscevcnt++;
157 	wake_up(&deviceconndiscwq);
158 }
159 
160 static const char *class_decode(const int class)
161 {
162 	int ix;
163 
164 	for (ix = 0; clas_info[ix].class != -1; ix++)
165 		if (clas_info[ix].class == class)
166 			break;
167 	return clas_info[ix].class_name;
168 }
169 
170 static char *usb_dump_endpoint_descriptor(
171 	int speed,
172 	char *start,
173 	char *end,
174 	const struct usb_endpoint_descriptor *desc
175 )
176 {
177 	char dir, unit, *type;
178 	unsigned interval, bandwidth = 1;
179 
180 	if (start > end)
181 		return start;
182 
183 	dir = usb_endpoint_dir_in(desc) ? 'I' : 'O';
184 
185 	if (speed == USB_SPEED_HIGH) {
186 		switch (le16_to_cpu(desc->wMaxPacketSize) & (0x03 << 11)) {
187 		case 1 << 11:	bandwidth = 2; break;
188 		case 2 << 11:	bandwidth = 3; break;
189 		}
190 	}
191 
192 	/* this isn't checking for illegal values */
193 	switch (desc->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) {
194 	case USB_ENDPOINT_XFER_CONTROL:
195 		type = "Ctrl";
196 		if (speed == USB_SPEED_HIGH) 	/* uframes per NAK */
197 			interval = desc->bInterval;
198 		else
199 			interval = 0;
200 		dir = 'B';			/* ctrl is bidirectional */
201 		break;
202 	case USB_ENDPOINT_XFER_ISOC:
203 		type = "Isoc";
204 		interval = 1 << (desc->bInterval - 1);
205 		break;
206 	case USB_ENDPOINT_XFER_BULK:
207 		type = "Bulk";
208 		if (speed == USB_SPEED_HIGH && dir == 'O') /* uframes per NAK */
209 			interval = desc->bInterval;
210 		else
211 			interval = 0;
212 		break;
213 	case USB_ENDPOINT_XFER_INT:
214 		type = "Int.";
215 		if (speed == USB_SPEED_HIGH)
216 			interval = 1 << (desc->bInterval - 1);
217 		else
218 			interval = desc->bInterval;
219 		break;
220 	default:	/* "can't happen" */
221 		return start;
222 	}
223 	interval *= (speed == USB_SPEED_HIGH) ? 125 : 1000;
224 	if (interval % 1000)
225 		unit = 'u';
226 	else {
227 		unit = 'm';
228 		interval /= 1000;
229 	}
230 
231 	start += sprintf(start, format_endpt, desc->bEndpointAddress, dir,
232 			 desc->bmAttributes, type,
233 			 (le16_to_cpu(desc->wMaxPacketSize) & 0x07ff) * bandwidth,
234 			 interval, unit);
235 	return start;
236 }
237 
238 static char *usb_dump_interface_descriptor(char *start, char *end,
239 	const struct usb_interface_cache *intfc,
240 	const struct usb_interface *iface,
241 	int setno)
242 {
243 	const struct usb_interface_descriptor *desc = &intfc->altsetting[setno].desc;
244 	const char *driver_name = "";
245 	int active = 0;
246 
247 	if (start > end)
248 		return start;
249 	if (iface) {
250 		driver_name = (iface->dev.driver
251 				? iface->dev.driver->name
252 				: "(none)");
253 		active = (desc == &iface->cur_altsetting->desc);
254 	}
255 	start += sprintf(start, format_iface,
256 			 active ? '*' : ' ',	/* mark active altsetting */
257 			 desc->bInterfaceNumber,
258 			 desc->bAlternateSetting,
259 			 desc->bNumEndpoints,
260 			 desc->bInterfaceClass,
261 			 class_decode(desc->bInterfaceClass),
262 			 desc->bInterfaceSubClass,
263 			 desc->bInterfaceProtocol,
264 			 driver_name);
265 	return start;
266 }
267 
268 static char *usb_dump_interface(
269 	int speed,
270 	char *start,
271 	char *end,
272 	const struct usb_interface_cache *intfc,
273 	const struct usb_interface *iface,
274 	int setno
275 ) {
276 	const struct usb_host_interface *desc = &intfc->altsetting[setno];
277 	int i;
278 
279 	start = usb_dump_interface_descriptor(start, end, intfc, iface, setno);
280 	for (i = 0; i < desc->desc.bNumEndpoints; i++) {
281 		if (start > end)
282 			return start;
283 		start = usb_dump_endpoint_descriptor(speed,
284 				start, end, &desc->endpoint[i].desc);
285 	}
286 	return start;
287 }
288 
289 /* TBD:
290  * 0. TBDs
291  * 1. marking active interface altsettings (code lists all, but should mark
292  *    which ones are active, if any)
293  */
294 
295 static char *usb_dump_config_descriptor(char *start, char *end, const struct usb_config_descriptor *desc, int active)
296 {
297 	if (start > end)
298 		return start;
299 	start += sprintf(start, format_config,
300 			 active ? '*' : ' ',	/* mark active/actual/current cfg. */
301 			 desc->bNumInterfaces,
302 			 desc->bConfigurationValue,
303 			 desc->bmAttributes,
304 			 desc->bMaxPower * 2);
305 	return start;
306 }
307 
308 static char *usb_dump_config (
309 	int speed,
310 	char *start,
311 	char *end,
312 	const struct usb_host_config *config,
313 	int active
314 )
315 {
316 	int i, j;
317 	struct usb_interface_cache *intfc;
318 	struct usb_interface *interface;
319 
320 	if (start > end)
321 		return start;
322 	if (!config)		/* getting these some in 2.3.7; none in 2.3.6 */
323 		return start + sprintf(start, "(null Cfg. desc.)\n");
324 	start = usb_dump_config_descriptor(start, end, &config->desc, active);
325 	for (i = 0; i < config->desc.bNumInterfaces; i++) {
326 		intfc = config->intf_cache[i];
327 		interface = config->interface[i];
328 		for (j = 0; j < intfc->num_altsetting; j++) {
329 			if (start > end)
330 				return start;
331 			start = usb_dump_interface(speed,
332 				start, end, intfc, interface, j);
333 		}
334 	}
335 	return start;
336 }
337 
338 /*
339  * Dump the different USB descriptors.
340  */
341 static char *usb_dump_device_descriptor(char *start, char *end, const struct usb_device_descriptor *desc)
342 {
343 	u16 bcdUSB = le16_to_cpu(desc->bcdUSB);
344 	u16 bcdDevice = le16_to_cpu(desc->bcdDevice);
345 
346 	if (start > end)
347 		return start;
348 	start += sprintf(start, format_device1,
349 			  bcdUSB >> 8, bcdUSB & 0xff,
350 			  desc->bDeviceClass,
351 			  class_decode (desc->bDeviceClass),
352 			  desc->bDeviceSubClass,
353 			  desc->bDeviceProtocol,
354 			  desc->bMaxPacketSize0,
355 			  desc->bNumConfigurations);
356 	if (start > end)
357 		return start;
358 	start += sprintf(start, format_device2,
359 			 le16_to_cpu(desc->idVendor),
360 			 le16_to_cpu(desc->idProduct),
361 			 bcdDevice >> 8, bcdDevice & 0xff);
362 	return start;
363 }
364 
365 /*
366  * Dump the different strings that this device holds.
367  */
368 static char *usb_dump_device_strings(char *start, char *end, struct usb_device *dev)
369 {
370 	if (start > end)
371 		return start;
372 	if (dev->manufacturer)
373 		start += sprintf(start, format_string_manufacturer, dev->manufacturer);
374 	if (start > end)
375 		goto out;
376 	if (dev->product)
377 		start += sprintf(start, format_string_product, dev->product);
378 	if (start > end)
379 		goto out;
380 #ifdef ALLOW_SERIAL_NUMBER
381 	if (dev->serial)
382 		start += sprintf(start, format_string_serialnumber, dev->serial);
383 #endif
384  out:
385 	return start;
386 }
387 
388 static char *usb_dump_desc(char *start, char *end, struct usb_device *dev)
389 {
390 	int i;
391 
392 	if (start > end)
393 		return start;
394 
395 	start = usb_dump_device_descriptor(start, end, &dev->descriptor);
396 
397 	if (start > end)
398 		return start;
399 
400 	start = usb_dump_device_strings(start, end, dev);
401 
402 	for (i = 0; i < dev->descriptor.bNumConfigurations; i++) {
403 		if (start > end)
404 			return start;
405 		start = usb_dump_config(dev->speed,
406 				start, end, dev->config + i,
407 				/* active ? */
408 				(dev->config + i) == dev->actconfig);
409 	}
410 	return start;
411 }
412 
413 
414 #ifdef PROC_EXTRA /* TBD: may want to add this code later */
415 
416 static char *usb_dump_hub_descriptor(char *start, char *end, const struct usb_hub_descriptor * desc)
417 {
418 	int leng = USB_DT_HUB_NONVAR_SIZE;
419 	unsigned char *ptr = (unsigned char *)desc;
420 
421 	if (start > end)
422 		return start;
423 	start += sprintf(start, "Interface:");
424 	while (leng && start <= end) {
425 		start += sprintf(start, " %02x", *ptr);
426 		ptr++; leng--;
427 	}
428 	*start++ = '\n';
429 	return start;
430 }
431 
432 static char *usb_dump_string(char *start, char *end, const struct usb_device *dev, char *id, int index)
433 {
434 	if (start > end)
435 		return start;
436 	start += sprintf(start, "Interface:");
437 	if (index <= dev->maxstring && dev->stringindex && dev->stringindex[index])
438 		start += sprintf(start, "%s: %.100s ", id, dev->stringindex[index]);
439 	return start;
440 }
441 
442 #endif /* PROC_EXTRA */
443 
444 /*****************************************************************/
445 
446 /* This is a recursive function. Parameters:
447  * buffer - the user-space buffer to write data into
448  * nbytes - the maximum number of bytes to write
449  * skip_bytes - the number of bytes to skip before writing anything
450  * file_offset - the offset into the devices file on completion
451  * The caller must own the device lock.
452  */
453 static ssize_t usb_device_dump(char __user **buffer, size_t *nbytes, loff_t *skip_bytes, loff_t *file_offset,
454 				struct usb_device *usbdev, struct usb_bus *bus, int level, int index, int count)
455 {
456 	int chix;
457 	int ret, cnt = 0;
458 	int parent_devnum = 0;
459 	char *pages_start, *data_end, *speed;
460 	unsigned int length;
461 	ssize_t total_written = 0;
462 
463 	/* don't bother with anything else if we're not writing any data */
464 	if (*nbytes <= 0)
465 		return 0;
466 
467 	if (level > MAX_TOPO_LEVEL)
468 		return 0;
469 	/* allocate 2^1 pages = 8K (on i386); should be more than enough for one device */
470         if (!(pages_start = (char*) __get_free_pages(GFP_KERNEL,1)))
471                 return -ENOMEM;
472 
473 	if (usbdev->parent && usbdev->parent->devnum != -1)
474 		parent_devnum = usbdev->parent->devnum;
475 	/*
476 	 * So the root hub's parent is 0 and any device that is
477 	 * plugged into the root hub has a parent of 0.
478 	 */
479 	switch (usbdev->speed) {
480 	case USB_SPEED_LOW:
481 		speed = "1.5"; break;
482 	case USB_SPEED_UNKNOWN:		/* usb 1.1 root hub code */
483 	case USB_SPEED_FULL:
484 		speed = "12 "; break;
485 	case USB_SPEED_HIGH:
486 		speed = "480"; break;
487 	default:
488 		speed = "?? ";
489 	}
490 	data_end = pages_start + sprintf(pages_start, format_topo,
491 			bus->busnum, level, parent_devnum,
492 			index, count, usbdev->devnum,
493 			speed, usbdev->maxchild);
494 	/*
495 	 * level = topology-tier level;
496 	 * parent_devnum = parent device number;
497 	 * index = parent's connector number;
498 	 * count = device count at this level
499 	 */
500 	/* If this is the root hub, display the bandwidth information */
501 	if (level == 0) {
502 		int	max;
503 
504 		/* high speed reserves 80%, full/low reserves 90% */
505 		if (usbdev->speed == USB_SPEED_HIGH)
506 			max = 800;
507 		else
508 			max = FRAME_TIME_MAX_USECS_ALLOC;
509 
510 		/* report "average" periodic allocation over a microsecond.
511 		 * the schedules are actually bursty, HCDs need to deal with
512 		 * that and just compute/report this average.
513 		 */
514 		data_end += sprintf(data_end, format_bandwidth,
515 				bus->bandwidth_allocated, max,
516 				(100 * bus->bandwidth_allocated + max / 2)
517 					/ max,
518 			         bus->bandwidth_int_reqs,
519 				 bus->bandwidth_isoc_reqs);
520 
521 	}
522 	data_end = usb_dump_desc(data_end, pages_start + (2 * PAGE_SIZE) - 256, usbdev);
523 
524 	if (data_end > (pages_start + (2 * PAGE_SIZE) - 256))
525 		data_end += sprintf(data_end, "(truncated)\n");
526 
527 	length = data_end - pages_start;
528 	/* if we can start copying some data to the user */
529 	if (length > *skip_bytes) {
530 		length -= *skip_bytes;
531 		if (length > *nbytes)
532 			length = *nbytes;
533 		if (copy_to_user(*buffer, pages_start + *skip_bytes, length)) {
534 			free_pages((unsigned long)pages_start, 1);
535 			return -EFAULT;
536 		}
537 		*nbytes -= length;
538 		*file_offset += length;
539 		total_written += length;
540 		*buffer += length;
541 		*skip_bytes = 0;
542 	} else
543 		*skip_bytes -= length;
544 
545 	free_pages((unsigned long)pages_start, 1);
546 
547 	/* Now look at all of this device's children. */
548 	for (chix = 0; chix < usbdev->maxchild; chix++) {
549 		struct usb_device *childdev = usbdev->children[chix];
550 
551 		if (childdev) {
552 			usb_lock_device(childdev);
553 			ret = usb_device_dump(buffer, nbytes, skip_bytes, file_offset, childdev,
554 					bus, level + 1, chix, ++cnt);
555 			usb_unlock_device(childdev);
556 			if (ret == -EFAULT)
557 				return total_written;
558 			total_written += ret;
559 		}
560 	}
561 	return total_written;
562 }
563 
564 static ssize_t usb_device_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
565 {
566 	struct usb_bus *bus;
567 	ssize_t ret, total_written = 0;
568 	loff_t skip_bytes = *ppos;
569 
570 	if (*ppos < 0)
571 		return -EINVAL;
572 	if (nbytes <= 0)
573 		return 0;
574 	if (!access_ok(VERIFY_WRITE, buf, nbytes))
575 		return -EFAULT;
576 
577 	mutex_lock(&usb_bus_list_lock);
578 	/* print devices for all busses */
579 	list_for_each_entry(bus, &usb_bus_list, bus_list) {
580 		/* recurse through all children of the root hub */
581 		if (!bus->root_hub)
582 			continue;
583 		usb_lock_device(bus->root_hub);
584 		ret = usb_device_dump(&buf, &nbytes, &skip_bytes, ppos, bus->root_hub, bus, 0, 0, 0);
585 		usb_unlock_device(bus->root_hub);
586 		if (ret < 0) {
587 			mutex_unlock(&usb_bus_list_lock);
588 			return ret;
589 		}
590 		total_written += ret;
591 	}
592 	mutex_unlock(&usb_bus_list_lock);
593 	return total_written;
594 }
595 
596 /* Kernel lock for "lastev" protection */
597 static unsigned int usb_device_poll(struct file *file, struct poll_table_struct *wait)
598 {
599 	struct usb_device_status *st = file->private_data;
600 	unsigned int mask = 0;
601 
602 	lock_kernel();
603 	if (!st) {
604 		st = kmalloc(sizeof(struct usb_device_status), GFP_KERNEL);
605 
606 		/* we may have dropped BKL - need to check for having lost the race */
607 		if (file->private_data) {
608 			kfree(st);
609 			st = file->private_data;
610 			goto lost_race;
611 		}
612 		/* we haven't lost - check for allocation failure now */
613 		if (!st) {
614 			unlock_kernel();
615 			return POLLIN;
616 		}
617 
618 		/*
619 		 * need to prevent the module from being unloaded, since
620 		 * proc_unregister does not call the release method and
621 		 * we would have a memory leak
622 		 */
623 		st->lastev = conndiscevcnt;
624 		file->private_data = st;
625 		mask = POLLIN;
626 	}
627 lost_race:
628 	if (file->f_mode & FMODE_READ)
629                 poll_wait(file, &deviceconndiscwq, wait);
630 	if (st->lastev != conndiscevcnt)
631 		mask |= POLLIN;
632 	st->lastev = conndiscevcnt;
633 	unlock_kernel();
634 	return mask;
635 }
636 
637 static int usb_device_open(struct inode *inode, struct file *file)
638 {
639         file->private_data = NULL;
640         return 0;
641 }
642 
643 static int usb_device_release(struct inode *inode, struct file *file)
644 {
645 	kfree(file->private_data);
646 	file->private_data = NULL;
647         return 0;
648 }
649 
650 static loff_t usb_device_lseek(struct file * file, loff_t offset, int orig)
651 {
652 	loff_t ret;
653 
654 	lock_kernel();
655 
656 	switch (orig) {
657 	case 0:
658 		file->f_pos = offset;
659 		ret = file->f_pos;
660 		break;
661 	case 1:
662 		file->f_pos += offset;
663 		ret = file->f_pos;
664 		break;
665 	case 2:
666 	default:
667 		ret = -EINVAL;
668 	}
669 
670 	unlock_kernel();
671 	return ret;
672 }
673 
674 const struct file_operations usbfs_devices_fops = {
675 	.llseek =	usb_device_lseek,
676 	.read =		usb_device_read,
677 	.poll =		usb_device_poll,
678 	.open =		usb_device_open,
679 	.release =	usb_device_release,
680 };
681