xref: /linux/drivers/usb/core/devices.c (revision b0148a98ec5151fec82064d95f11eb9efbc628ea)
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 	down_read(&usb_bus_type.subsys.rwsem);
250 	if (iface) {
251 		driver_name = (iface->dev.driver
252 				? iface->dev.driver->name
253 				: "(none)");
254 		active = (desc == &iface->cur_altsetting->desc);
255 	}
256 	start += sprintf(start, format_iface,
257 			 active ? '*' : ' ',	/* mark active altsetting */
258 			 desc->bInterfaceNumber,
259 			 desc->bAlternateSetting,
260 			 desc->bNumEndpoints,
261 			 desc->bInterfaceClass,
262 			 class_decode(desc->bInterfaceClass),
263 			 desc->bInterfaceSubClass,
264 			 desc->bInterfaceProtocol,
265 			 driver_name);
266 	up_read(&usb_bus_type.subsys.rwsem);
267 	return start;
268 }
269 
270 static char *usb_dump_interface(
271 	int speed,
272 	char *start,
273 	char *end,
274 	const struct usb_interface_cache *intfc,
275 	const struct usb_interface *iface,
276 	int setno
277 ) {
278 	const struct usb_host_interface *desc = &intfc->altsetting[setno];
279 	int i;
280 
281 	start = usb_dump_interface_descriptor(start, end, intfc, iface, setno);
282 	for (i = 0; i < desc->desc.bNumEndpoints; i++) {
283 		if (start > end)
284 			return start;
285 		start = usb_dump_endpoint_descriptor(speed,
286 				start, end, &desc->endpoint[i].desc);
287 	}
288 	return start;
289 }
290 
291 /* TBD:
292  * 0. TBDs
293  * 1. marking active interface altsettings (code lists all, but should mark
294  *    which ones are active, if any)
295  */
296 
297 static char *usb_dump_config_descriptor(char *start, char *end, const struct usb_config_descriptor *desc, int active)
298 {
299 	if (start > end)
300 		return start;
301 	start += sprintf(start, format_config,
302 			 active ? '*' : ' ',	/* mark active/actual/current cfg. */
303 			 desc->bNumInterfaces,
304 			 desc->bConfigurationValue,
305 			 desc->bmAttributes,
306 			 desc->bMaxPower * 2);
307 	return start;
308 }
309 
310 static char *usb_dump_config (
311 	int speed,
312 	char *start,
313 	char *end,
314 	const struct usb_host_config *config,
315 	int active
316 )
317 {
318 	int i, j;
319 	struct usb_interface_cache *intfc;
320 	struct usb_interface *interface;
321 
322 	if (start > end)
323 		return start;
324 	if (!config)		/* getting these some in 2.3.7; none in 2.3.6 */
325 		return start + sprintf(start, "(null Cfg. desc.)\n");
326 	start = usb_dump_config_descriptor(start, end, &config->desc, active);
327 	for (i = 0; i < config->desc.bNumInterfaces; i++) {
328 		intfc = config->intf_cache[i];
329 		interface = config->interface[i];
330 		for (j = 0; j < intfc->num_altsetting; j++) {
331 			if (start > end)
332 				return start;
333 			start = usb_dump_interface(speed,
334 				start, end, intfc, interface, j);
335 		}
336 	}
337 	return start;
338 }
339 
340 /*
341  * Dump the different USB descriptors.
342  */
343 static char *usb_dump_device_descriptor(char *start, char *end, const struct usb_device_descriptor *desc)
344 {
345 	u16 bcdUSB = le16_to_cpu(desc->bcdUSB);
346 	u16 bcdDevice = le16_to_cpu(desc->bcdDevice);
347 
348 	if (start > end)
349 		return start;
350 	start += sprintf(start, format_device1,
351 			  bcdUSB >> 8, bcdUSB & 0xff,
352 			  desc->bDeviceClass,
353 			  class_decode (desc->bDeviceClass),
354 			  desc->bDeviceSubClass,
355 			  desc->bDeviceProtocol,
356 			  desc->bMaxPacketSize0,
357 			  desc->bNumConfigurations);
358 	if (start > end)
359 		return start;
360 	start += sprintf(start, format_device2,
361 			 le16_to_cpu(desc->idVendor),
362 			 le16_to_cpu(desc->idProduct),
363 			 bcdDevice >> 8, bcdDevice & 0xff);
364 	return start;
365 }
366 
367 /*
368  * Dump the different strings that this device holds.
369  */
370 static char *usb_dump_device_strings(char *start, char *end, struct usb_device *dev)
371 {
372 	if (start > end)
373 		return start;
374 	if (dev->manufacturer)
375 		start += sprintf(start, format_string_manufacturer, dev->manufacturer);
376 	if (start > end)
377 		goto out;
378 	if (dev->product)
379 		start += sprintf(start, format_string_product, dev->product);
380 	if (start > end)
381 		goto out;
382 #ifdef ALLOW_SERIAL_NUMBER
383 	if (dev->serial)
384 		start += sprintf(start, format_string_serialnumber, dev->serial);
385 #endif
386  out:
387 	return start;
388 }
389 
390 static char *usb_dump_desc(char *start, char *end, struct usb_device *dev)
391 {
392 	int i;
393 
394 	if (start > end)
395 		return start;
396 
397 	start = usb_dump_device_descriptor(start, end, &dev->descriptor);
398 
399 	if (start > end)
400 		return start;
401 
402 	start = usb_dump_device_strings(start, end, dev);
403 
404 	for (i = 0; i < dev->descriptor.bNumConfigurations; i++) {
405 		if (start > end)
406 			return start;
407 		start = usb_dump_config(dev->speed,
408 				start, end, dev->config + i,
409 				/* active ? */
410 				(dev->config + i) == dev->actconfig);
411 	}
412 	return start;
413 }
414 
415 
416 #ifdef PROC_EXTRA /* TBD: may want to add this code later */
417 
418 static char *usb_dump_hub_descriptor(char *start, char *end, const struct usb_hub_descriptor * desc)
419 {
420 	int leng = USB_DT_HUB_NONVAR_SIZE;
421 	unsigned char *ptr = (unsigned char *)desc;
422 
423 	if (start > end)
424 		return start;
425 	start += sprintf(start, "Interface:");
426 	while (leng && start <= end) {
427 		start += sprintf(start, " %02x", *ptr);
428 		ptr++; leng--;
429 	}
430 	*start++ = '\n';
431 	return start;
432 }
433 
434 static char *usb_dump_string(char *start, char *end, const struct usb_device *dev, char *id, int index)
435 {
436 	if (start > end)
437 		return start;
438 	start += sprintf(start, "Interface:");
439 	if (index <= dev->maxstring && dev->stringindex && dev->stringindex[index])
440 		start += sprintf(start, "%s: %.100s ", id, dev->stringindex[index]);
441 	return start;
442 }
443 
444 #endif /* PROC_EXTRA */
445 
446 /*****************************************************************/
447 
448 /* This is a recursive function. Parameters:
449  * buffer - the user-space buffer to write data into
450  * nbytes - the maximum number of bytes to write
451  * skip_bytes - the number of bytes to skip before writing anything
452  * file_offset - the offset into the devices file on completion
453  * The caller must own the device lock.
454  */
455 static ssize_t usb_device_dump(char __user **buffer, size_t *nbytes, loff_t *skip_bytes, loff_t *file_offset,
456 				struct usb_device *usbdev, struct usb_bus *bus, int level, int index, int count)
457 {
458 	int chix;
459 	int ret, cnt = 0;
460 	int parent_devnum = 0;
461 	char *pages_start, *data_end, *speed;
462 	unsigned int length;
463 	ssize_t total_written = 0;
464 
465 	/* don't bother with anything else if we're not writing any data */
466 	if (*nbytes <= 0)
467 		return 0;
468 
469 	if (level > MAX_TOPO_LEVEL)
470 		return 0;
471 	/* allocate 2^1 pages = 8K (on i386); should be more than enough for one device */
472         if (!(pages_start = (char*) __get_free_pages(GFP_KERNEL,1)))
473                 return -ENOMEM;
474 
475 	if (usbdev->parent && usbdev->parent->devnum != -1)
476 		parent_devnum = usbdev->parent->devnum;
477 	/*
478 	 * So the root hub's parent is 0 and any device that is
479 	 * plugged into the root hub has a parent of 0.
480 	 */
481 	switch (usbdev->speed) {
482 	case USB_SPEED_LOW:
483 		speed = "1.5"; break;
484 	case USB_SPEED_UNKNOWN:		/* usb 1.1 root hub code */
485 	case USB_SPEED_FULL:
486 		speed = "12 "; break;
487 	case USB_SPEED_HIGH:
488 		speed = "480"; break;
489 	default:
490 		speed = "?? ";
491 	}
492 	data_end = pages_start + sprintf(pages_start, format_topo,
493 			bus->busnum, level, parent_devnum,
494 			index, count, usbdev->devnum,
495 			speed, usbdev->maxchild);
496 	/*
497 	 * level = topology-tier level;
498 	 * parent_devnum = parent device number;
499 	 * index = parent's connector number;
500 	 * count = device count at this level
501 	 */
502 	/* If this is the root hub, display the bandwidth information */
503 	if (level == 0) {
504 		int	max;
505 
506 		/* high speed reserves 80%, full/low reserves 90% */
507 		if (usbdev->speed == USB_SPEED_HIGH)
508 			max = 800;
509 		else
510 			max = FRAME_TIME_MAX_USECS_ALLOC;
511 
512 		/* report "average" periodic allocation over a microsecond.
513 		 * the schedules are actually bursty, HCDs need to deal with
514 		 * that and just compute/report this average.
515 		 */
516 		data_end += sprintf(data_end, format_bandwidth,
517 				bus->bandwidth_allocated, max,
518 				(100 * bus->bandwidth_allocated + max / 2)
519 					/ max,
520 			         bus->bandwidth_int_reqs,
521 				 bus->bandwidth_isoc_reqs);
522 
523 	}
524 	data_end = usb_dump_desc(data_end, pages_start + (2 * PAGE_SIZE) - 256, usbdev);
525 
526 	if (data_end > (pages_start + (2 * PAGE_SIZE) - 256))
527 		data_end += sprintf(data_end, "(truncated)\n");
528 
529 	length = data_end - pages_start;
530 	/* if we can start copying some data to the user */
531 	if (length > *skip_bytes) {
532 		length -= *skip_bytes;
533 		if (length > *nbytes)
534 			length = *nbytes;
535 		if (copy_to_user(*buffer, pages_start + *skip_bytes, length)) {
536 			free_pages((unsigned long)pages_start, 1);
537 			return -EFAULT;
538 		}
539 		*nbytes -= length;
540 		*file_offset += length;
541 		total_written += length;
542 		*buffer += length;
543 		*skip_bytes = 0;
544 	} else
545 		*skip_bytes -= length;
546 
547 	free_pages((unsigned long)pages_start, 1);
548 
549 	/* Now look at all of this device's children. */
550 	for (chix = 0; chix < usbdev->maxchild; chix++) {
551 		struct usb_device *childdev = usbdev->children[chix];
552 
553 		if (childdev) {
554 			usb_lock_device(childdev);
555 			ret = usb_device_dump(buffer, nbytes, skip_bytes, file_offset, childdev,
556 					bus, level + 1, chix, ++cnt);
557 			usb_unlock_device(childdev);
558 			if (ret == -EFAULT)
559 				return total_written;
560 			total_written += ret;
561 		}
562 	}
563 	return total_written;
564 }
565 
566 static ssize_t usb_device_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
567 {
568 	struct usb_bus *bus;
569 	ssize_t ret, total_written = 0;
570 	loff_t skip_bytes = *ppos;
571 
572 	if (*ppos < 0)
573 		return -EINVAL;
574 	if (nbytes <= 0)
575 		return 0;
576 	if (!access_ok(VERIFY_WRITE, buf, nbytes))
577 		return -EFAULT;
578 
579 	mutex_lock(&usb_bus_list_lock);
580 	/* print devices for all busses */
581 	list_for_each_entry(bus, &usb_bus_list, bus_list) {
582 		/* recurse through all children of the root hub */
583 		if (!bus->root_hub)
584 			continue;
585 		usb_lock_device(bus->root_hub);
586 		ret = usb_device_dump(&buf, &nbytes, &skip_bytes, ppos, bus->root_hub, bus, 0, 0, 0);
587 		usb_unlock_device(bus->root_hub);
588 		if (ret < 0) {
589 			mutex_unlock(&usb_bus_list_lock);
590 			return ret;
591 		}
592 		total_written += ret;
593 	}
594 	mutex_unlock(&usb_bus_list_lock);
595 	return total_written;
596 }
597 
598 /* Kernel lock for "lastev" protection */
599 static unsigned int usb_device_poll(struct file *file, struct poll_table_struct *wait)
600 {
601 	struct usb_device_status *st = file->private_data;
602 	unsigned int mask = 0;
603 
604 	lock_kernel();
605 	if (!st) {
606 		st = kmalloc(sizeof(struct usb_device_status), GFP_KERNEL);
607 		if (!st) {
608 			unlock_kernel();
609 			return POLLIN;
610 		}
611 
612 		/* we may have dropped BKL - need to check for having lost the race */
613 		if (file->private_data) {
614 			kfree(st);
615 			st = file->private_data;
616 			goto lost_race;
617 		}
618 
619 		/*
620 		 * need to prevent the module from being unloaded, since
621 		 * proc_unregister does not call the release method and
622 		 * we would have a memory leak
623 		 */
624 		st->lastev = conndiscevcnt;
625 		file->private_data = st;
626 		mask = POLLIN;
627 	}
628 lost_race:
629 	if (file->f_mode & FMODE_READ)
630                 poll_wait(file, &deviceconndiscwq, wait);
631 	if (st->lastev != conndiscevcnt)
632 		mask |= POLLIN;
633 	st->lastev = conndiscevcnt;
634 	unlock_kernel();
635 	return mask;
636 }
637 
638 static int usb_device_open(struct inode *inode, struct file *file)
639 {
640         file->private_data = NULL;
641         return 0;
642 }
643 
644 static int usb_device_release(struct inode *inode, struct file *file)
645 {
646 	kfree(file->private_data);
647 	file->private_data = NULL;
648         return 0;
649 }
650 
651 static loff_t usb_device_lseek(struct file * file, loff_t offset, int orig)
652 {
653 	loff_t ret;
654 
655 	lock_kernel();
656 
657 	switch (orig) {
658 	case 0:
659 		file->f_pos = offset;
660 		ret = file->f_pos;
661 		break;
662 	case 1:
663 		file->f_pos += offset;
664 		ret = file->f_pos;
665 		break;
666 	case 2:
667 	default:
668 		ret = -EINVAL;
669 	}
670 
671 	unlock_kernel();
672 	return ret;
673 }
674 
675 const struct file_operations usbfs_devices_fops = {
676 	.llseek =	usb_device_lseek,
677 	.read =		usb_device_read,
678 	.poll =		usb_device_poll,
679 	.open =		usb_device_open,
680 	.release =	usb_device_release,
681 };
682