Merge branch 'devel' of master.kernel.org:/home/rmk/linux-2.6-arm
[linux-2.6] / drivers / usb / core / devices.c
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
51 #include <linux/fs.h>
52 #include <linux/mm.h>
53 #include <linux/slab.h>
54 #include <linux/poll.h>
55 #include <linux/usb.h>
56 #include <linux/smp_lock.h>
57 #include <linux/usbdevice_fs.h>
58 #include <linux/mutex.h>
59 #include <asm/uaccess.h>
60
61 #include "usb.h"
62 #include "hcd.h"
63
64 /* Define ALLOW_SERIAL_NUMBER if you want to see the serial number of devices */
65 #define ALLOW_SERIAL_NUMBER
66
67 static const char *format_topo =
68 /* T:  Bus=dd Lev=dd Prnt=dd Port=dd Cnt=dd Dev#=ddd Spd=ddd MxCh=dd */
69 "\nT:  Bus=%2.2d Lev=%2.2d Prnt=%2.2d Port=%2.2d Cnt=%2.2d Dev#=%3d Spd=%3s MxCh=%2d\n";
70
71 static const char *format_string_manufacturer =
72 /* S:  Manufacturer=xxxx */
73   "S:  Manufacturer=%.100s\n";
74
75 static const char *format_string_product =
76 /* S:  Product=xxxx */
77   "S:  Product=%.100s\n";
78
79 #ifdef ALLOW_SERIAL_NUMBER
80 static const char *format_string_serialnumber =
81 /* S:  SerialNumber=xxxx */
82   "S:  SerialNumber=%.100s\n";
83 #endif
84
85 static const char *format_bandwidth =
86 /* B:  Alloc=ddd/ddd us (xx%), #Int=ddd, #Iso=ddd */
87   "B:  Alloc=%3d/%3d us (%2d%%), #Int=%3d, #Iso=%3d\n";
88
89 static const char *format_device1 =
90 /* D:  Ver=xx.xx Cls=xx(sssss) Sub=xx Prot=xx MxPS=dd #Cfgs=dd */
91   "D:  Ver=%2x.%02x Cls=%02x(%-5s) Sub=%02x Prot=%02x MxPS=%2d #Cfgs=%3d\n";
92
93 static const char *format_device2 =
94 /* P:  Vendor=xxxx ProdID=xxxx Rev=xx.xx */
95   "P:  Vendor=%04x ProdID=%04x Rev=%2x.%02x\n";
96
97 static const char *format_config =
98 /* C:  #Ifs=dd Cfg#=dd Atr=xx MPwr=dddmA */
99   "C:%c #Ifs=%2d Cfg#=%2d Atr=%02x MxPwr=%3dmA\n";
100
101 static const char *format_iad =
102 /* A:  FirstIf#=dd IfCount=dd Cls=xx(sssss) Sub=xx Prot=xx */
103   "A:  FirstIf#=%2d IfCount=%2d Cls=%02x(%-5s) Sub=%02x Prot=%02x\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;
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         {USB_CLASS_VIDEO,               "video"},
150         {-1,                            "unk."}         /* leave as last */
151 };
152
153 /*****************************************************************/
154
155 void usbfs_conn_disc_event(void)
156 {
157         conndiscevcnt++;
158         wake_up(&deviceconndiscwq);
159 }
160
161 static const char *class_decode(const int class)
162 {
163         int ix;
164
165         for (ix = 0; clas_info[ix].class != -1; ix++)
166                 if (clas_info[ix].class == class)
167                         break;
168         return clas_info[ix].class_name;
169 }
170
171 static char *usb_dump_endpoint_descriptor(int speed, char *start, char *end,
172                                 const struct usb_endpoint_descriptor *desc)
173 {
174         char dir, unit, *type;
175         unsigned interval, bandwidth = 1;
176
177         if (start > end)
178                 return start;
179
180         dir = usb_endpoint_dir_in(desc) ? 'I' : 'O';
181
182         if (speed == USB_SPEED_HIGH) {
183                 switch (le16_to_cpu(desc->wMaxPacketSize) & (0x03 << 11)) {
184                 case 1 << 11:   bandwidth = 2; break;
185                 case 2 << 11:   bandwidth = 3; break;
186                 }
187         }
188
189         /* this isn't checking for illegal values */
190         switch (desc->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) {
191         case USB_ENDPOINT_XFER_CONTROL:
192                 type = "Ctrl";
193                 if (speed == USB_SPEED_HIGH)    /* uframes per NAK */
194                         interval = desc->bInterval;
195                 else
196                         interval = 0;
197                 dir = 'B';                      /* ctrl is bidirectional */
198                 break;
199         case USB_ENDPOINT_XFER_ISOC:
200                 type = "Isoc";
201                 interval = 1 << (desc->bInterval - 1);
202                 break;
203         case USB_ENDPOINT_XFER_BULK:
204                 type = "Bulk";
205                 if (speed == USB_SPEED_HIGH && dir == 'O') /* uframes per NAK */
206                         interval = desc->bInterval;
207                 else
208                         interval = 0;
209                 break;
210         case USB_ENDPOINT_XFER_INT:
211                 type = "Int.";
212                 if (speed == USB_SPEED_HIGH)
213                         interval = 1 << (desc->bInterval - 1);
214                 else
215                         interval = desc->bInterval;
216                 break;
217         default:        /* "can't happen" */
218                 return start;
219         }
220         interval *= (speed == USB_SPEED_HIGH) ? 125 : 1000;
221         if (interval % 1000)
222                 unit = 'u';
223         else {
224                 unit = 'm';
225                 interval /= 1000;
226         }
227
228         start += sprintf(start, format_endpt, desc->bEndpointAddress, dir,
229                          desc->bmAttributes, type,
230                          (le16_to_cpu(desc->wMaxPacketSize) & 0x07ff) *
231                          bandwidth,
232                          interval, unit);
233         return start;
234 }
235
236 static char *usb_dump_interface_descriptor(char *start, char *end,
237                                         const struct usb_interface_cache *intfc,
238                                         const struct usb_interface *iface,
239                                         int setno)
240 {
241         const struct usb_interface_descriptor *desc;
242         const char *driver_name = "";
243         int active = 0;
244
245         if (start > end)
246                 return start;
247         desc = &intfc->altsetting[setno].desc;
248         if (iface) {
249                 driver_name = (iface->dev.driver
250                                 ? iface->dev.driver->name
251                                 : "(none)");
252                 active = (desc == &iface->cur_altsetting->desc);
253         }
254         start += sprintf(start, format_iface,
255                          active ? '*' : ' ',    /* mark active altsetting */
256                          desc->bInterfaceNumber,
257                          desc->bAlternateSetting,
258                          desc->bNumEndpoints,
259                          desc->bInterfaceClass,
260                          class_decode(desc->bInterfaceClass),
261                          desc->bInterfaceSubClass,
262                          desc->bInterfaceProtocol,
263                          driver_name);
264         return start;
265 }
266
267 static char *usb_dump_interface(int speed, char *start, char *end,
268                                 const struct usb_interface_cache *intfc,
269                                 const struct usb_interface *iface, int setno)
270 {
271         const struct usb_host_interface *desc = &intfc->altsetting[setno];
272         int i;
273
274         start = usb_dump_interface_descriptor(start, end, intfc, iface, setno);
275         for (i = 0; i < desc->desc.bNumEndpoints; i++) {
276                 if (start > end)
277                         return start;
278                 start = usb_dump_endpoint_descriptor(speed,
279                                 start, end, &desc->endpoint[i].desc);
280         }
281         return start;
282 }
283
284 static char *usb_dump_iad_descriptor(char *start, char *end,
285                         const struct usb_interface_assoc_descriptor *iad)
286 {
287         if (start > end)
288                 return start;
289         start += sprintf(start, format_iad,
290                          iad->bFirstInterface,
291                          iad->bInterfaceCount,
292                          iad->bFunctionClass,
293                          class_decode(iad->bFunctionClass),
294                          iad->bFunctionSubClass,
295                          iad->bFunctionProtocol);
296         return start;
297 }
298
299 /* TBD:
300  * 0. TBDs
301  * 1. marking active interface altsettings (code lists all, but should mark
302  *    which ones are active, if any)
303  */
304 static char *usb_dump_config_descriptor(char *start, char *end,
305                                 const struct usb_config_descriptor *desc,
306                                 int active)
307 {
308         if (start > end)
309                 return start;
310         start += sprintf(start, format_config,
311                          /* mark active/actual/current cfg. */
312                          active ? '*' : ' ',
313                          desc->bNumInterfaces,
314                          desc->bConfigurationValue,
315                          desc->bmAttributes,
316                          desc->bMaxPower * 2);
317         return start;
318 }
319
320 static char *usb_dump_config(int speed, char *start, char *end,
321                              const struct usb_host_config *config, int active)
322 {
323         int i, j;
324         struct usb_interface_cache *intfc;
325         struct usb_interface *interface;
326
327         if (start > end)
328                 return start;
329         if (!config)
330                 /* getting these some in 2.3.7; none in 2.3.6 */
331                 return start + sprintf(start, "(null Cfg. desc.)\n");
332         start = usb_dump_config_descriptor(start, end, &config->desc, active);
333         for (i = 0; i < USB_MAXIADS; i++) {
334                 if (config->intf_assoc[i] == NULL)
335                         break;
336                 start = usb_dump_iad_descriptor(start, end,
337                                         config->intf_assoc[i]);
338         }
339         for (i = 0; i < config->desc.bNumInterfaces; i++) {
340                 intfc = config->intf_cache[i];
341                 interface = config->interface[i];
342                 for (j = 0; j < intfc->num_altsetting; j++) {
343                         if (start > end)
344                                 return start;
345                         start = usb_dump_interface(speed,
346                                 start, end, intfc, interface, j);
347                 }
348         }
349         return start;
350 }
351
352 /*
353  * Dump the different USB descriptors.
354  */
355 static char *usb_dump_device_descriptor(char *start, char *end,
356                                 const struct usb_device_descriptor *desc)
357 {
358         u16 bcdUSB = le16_to_cpu(desc->bcdUSB);
359         u16 bcdDevice = le16_to_cpu(desc->bcdDevice);
360
361         if (start > end)
362                 return start;
363         start += sprintf(start, format_device1,
364                           bcdUSB >> 8, bcdUSB & 0xff,
365                           desc->bDeviceClass,
366                           class_decode(desc->bDeviceClass),
367                           desc->bDeviceSubClass,
368                           desc->bDeviceProtocol,
369                           desc->bMaxPacketSize0,
370                           desc->bNumConfigurations);
371         if (start > end)
372                 return start;
373         start += sprintf(start, format_device2,
374                          le16_to_cpu(desc->idVendor),
375                          le16_to_cpu(desc->idProduct),
376                          bcdDevice >> 8, bcdDevice & 0xff);
377         return start;
378 }
379
380 /*
381  * Dump the different strings that this device holds.
382  */
383 static char *usb_dump_device_strings(char *start, char *end,
384                                      struct usb_device *dev)
385 {
386         if (start > end)
387                 return start;
388         if (dev->manufacturer)
389                 start += sprintf(start, format_string_manufacturer,
390                                  dev->manufacturer);
391         if (start > end)
392                 goto out;
393         if (dev->product)
394                 start += sprintf(start, format_string_product, dev->product);
395         if (start > end)
396                 goto out;
397 #ifdef ALLOW_SERIAL_NUMBER
398         if (dev->serial)
399                 start += sprintf(start, format_string_serialnumber,
400                                  dev->serial);
401 #endif
402  out:
403         return start;
404 }
405
406 static char *usb_dump_desc(char *start, char *end, struct usb_device *dev)
407 {
408         int i;
409
410         if (start > end)
411                 return start;
412
413         start = usb_dump_device_descriptor(start, end, &dev->descriptor);
414
415         if (start > end)
416                 return start;
417
418         start = usb_dump_device_strings(start, end, dev);
419
420         for (i = 0; i < dev->descriptor.bNumConfigurations; i++) {
421                 if (start > end)
422                         return start;
423                 start = usb_dump_config(dev->speed,
424                                 start, end, dev->config + i,
425                                 /* active ? */
426                                 (dev->config + i) == dev->actconfig);
427         }
428         return start;
429 }
430
431
432 #ifdef PROC_EXTRA /* TBD: may want to add this code later */
433
434 static char *usb_dump_hub_descriptor(char *start, char *end,
435                                      const struct usb_hub_descriptor *desc)
436 {
437         int leng = USB_DT_HUB_NONVAR_SIZE;
438         unsigned char *ptr = (unsigned char *)desc;
439
440         if (start > end)
441                 return start;
442         start += sprintf(start, "Interface:");
443         while (leng && start <= end) {
444                 start += sprintf(start, " %02x", *ptr);
445                 ptr++; leng--;
446         }
447         *start++ = '\n';
448         return start;
449 }
450
451 static char *usb_dump_string(char *start, char *end,
452                              const struct usb_device *dev, char *id, int index)
453 {
454         if (start > end)
455                 return start;
456         start += sprintf(start, "Interface:");
457         if (index <= dev->maxstring && dev->stringindex &&
458             dev->stringindex[index])
459                 start += sprintf(start, "%s: %.100s ", id,
460                                  dev->stringindex[index]);
461         return start;
462 }
463
464 #endif /* PROC_EXTRA */
465
466 /*****************************************************************/
467
468 /* This is a recursive function. Parameters:
469  * buffer - the user-space buffer to write data into
470  * nbytes - the maximum number of bytes to write
471  * skip_bytes - the number of bytes to skip before writing anything
472  * file_offset - the offset into the devices file on completion
473  * The caller must own the device lock.
474  */
475 static ssize_t usb_device_dump(char __user **buffer, size_t *nbytes,
476                                loff_t *skip_bytes, loff_t *file_offset,
477                                struct usb_device *usbdev, struct usb_bus *bus,
478                                int level, int index, int count)
479 {
480         int chix;
481         int ret, cnt = 0;
482         int parent_devnum = 0;
483         char *pages_start, *data_end, *speed;
484         unsigned int length;
485         ssize_t total_written = 0;
486
487         /* don't bother with anything else if we're not writing any data */
488         if (*nbytes <= 0)
489                 return 0;
490
491         if (level > MAX_TOPO_LEVEL)
492                 return 0;
493         /* allocate 2^1 pages = 8K (on i386);
494          * should be more than enough for one device */
495         pages_start = (char *)__get_free_pages(GFP_KERNEL, 1);
496         if (!pages_start)
497                 return -ENOMEM;
498
499         if (usbdev->parent && usbdev->parent->devnum != -1)
500                 parent_devnum = usbdev->parent->devnum;
501         /*
502          * So the root hub's parent is 0 and any device that is
503          * plugged into the root hub has a parent of 0.
504          */
505         switch (usbdev->speed) {
506         case USB_SPEED_LOW:
507                 speed = "1.5"; break;
508         case USB_SPEED_UNKNOWN:         /* usb 1.1 root hub code */
509         case USB_SPEED_FULL:
510                 speed = "12 "; break;
511         case USB_SPEED_HIGH:
512                 speed = "480"; break;
513         default:
514                 speed = "?? ";
515         }
516         data_end = pages_start + sprintf(pages_start, format_topo,
517                         bus->busnum, level, parent_devnum,
518                         index, count, usbdev->devnum,
519                         speed, usbdev->maxchild);
520         /*
521          * level = topology-tier level;
522          * parent_devnum = parent device number;
523          * index = parent's connector number;
524          * count = device count at this level
525          */
526         /* If this is the root hub, display the bandwidth information */
527         if (level == 0) {
528                 int     max;
529
530                 /* high speed reserves 80%, full/low reserves 90% */
531                 if (usbdev->speed == USB_SPEED_HIGH)
532                         max = 800;
533                 else
534                         max = FRAME_TIME_MAX_USECS_ALLOC;
535
536                 /* report "average" periodic allocation over a microsecond.
537                  * the schedules are actually bursty, HCDs need to deal with
538                  * that and just compute/report this average.
539                  */
540                 data_end += sprintf(data_end, format_bandwidth,
541                                 bus->bandwidth_allocated, max,
542                                 (100 * bus->bandwidth_allocated + max / 2)
543                                         / max,
544                                 bus->bandwidth_int_reqs,
545                                 bus->bandwidth_isoc_reqs);
546
547         }
548         data_end = usb_dump_desc(data_end, pages_start + (2 * PAGE_SIZE) - 256,
549                                  usbdev);
550
551         if (data_end > (pages_start + (2 * PAGE_SIZE) - 256))
552                 data_end += sprintf(data_end, "(truncated)\n");
553
554         length = data_end - pages_start;
555         /* if we can start copying some data to the user */
556         if (length > *skip_bytes) {
557                 length -= *skip_bytes;
558                 if (length > *nbytes)
559                         length = *nbytes;
560                 if (copy_to_user(*buffer, pages_start + *skip_bytes, length)) {
561                         free_pages((unsigned long)pages_start, 1);
562                         return -EFAULT;
563                 }
564                 *nbytes -= length;
565                 *file_offset += length;
566                 total_written += length;
567                 *buffer += length;
568                 *skip_bytes = 0;
569         } else
570                 *skip_bytes -= length;
571
572         free_pages((unsigned long)pages_start, 1);
573
574         /* Now look at all of this device's children. */
575         for (chix = 0; chix < usbdev->maxchild; chix++) {
576                 struct usb_device *childdev = usbdev->children[chix];
577
578                 if (childdev) {
579                         usb_lock_device(childdev);
580                         ret = usb_device_dump(buffer, nbytes, skip_bytes,
581                                               file_offset, childdev, bus,
582                                               level + 1, chix, ++cnt);
583                         usb_unlock_device(childdev);
584                         if (ret == -EFAULT)
585                                 return total_written;
586                         total_written += ret;
587                 }
588         }
589         return total_written;
590 }
591
592 static ssize_t usb_device_read(struct file *file, char __user *buf,
593                                size_t nbytes, loff_t *ppos)
594 {
595         struct usb_bus *bus;
596         ssize_t ret, total_written = 0;
597         loff_t skip_bytes = *ppos;
598
599         if (*ppos < 0)
600                 return -EINVAL;
601         if (nbytes <= 0)
602                 return 0;
603         if (!access_ok(VERIFY_WRITE, buf, nbytes))
604                 return -EFAULT;
605
606         mutex_lock(&usb_bus_list_lock);
607         /* print devices for all busses */
608         list_for_each_entry(bus, &usb_bus_list, bus_list) {
609                 /* recurse through all children of the root hub */
610                 if (!bus->root_hub)
611                         continue;
612                 usb_lock_device(bus->root_hub);
613                 ret = usb_device_dump(&buf, &nbytes, &skip_bytes, ppos,
614                                       bus->root_hub, bus, 0, 0, 0);
615                 usb_unlock_device(bus->root_hub);
616                 if (ret < 0) {
617                         mutex_unlock(&usb_bus_list_lock);
618                         return ret;
619                 }
620                 total_written += ret;
621         }
622         mutex_unlock(&usb_bus_list_lock);
623         return total_written;
624 }
625
626 /* Kernel lock for "lastev" protection */
627 static unsigned int usb_device_poll(struct file *file,
628                                     struct poll_table_struct *wait)
629 {
630         struct usb_device_status *st = file->private_data;
631         unsigned int mask = 0;
632
633         lock_kernel();
634         if (!st) {
635                 st = kmalloc(sizeof(struct usb_device_status), GFP_KERNEL);
636
637                 /* we may have dropped BKL -
638                  * need to check for having lost the race */
639                 if (file->private_data) {
640                         kfree(st);
641                         st = file->private_data;
642                         goto lost_race;
643                 }
644                 /* we haven't lost - check for allocation failure now */
645                 if (!st) {
646                         unlock_kernel();
647                         return POLLIN;
648                 }
649
650                 /*
651                  * need to prevent the module from being unloaded, since
652                  * proc_unregister does not call the release method and
653                  * we would have a memory leak
654                  */
655                 st->lastev = conndiscevcnt;
656                 file->private_data = st;
657                 mask = POLLIN;
658         }
659 lost_race:
660         if (file->f_mode & FMODE_READ)
661                 poll_wait(file, &deviceconndiscwq, wait);
662         if (st->lastev != conndiscevcnt)
663                 mask |= POLLIN;
664         st->lastev = conndiscevcnt;
665         unlock_kernel();
666         return mask;
667 }
668
669 static int usb_device_open(struct inode *inode, struct file *file)
670 {
671         file->private_data = NULL;
672         return 0;
673 }
674
675 static int usb_device_release(struct inode *inode, struct file *file)
676 {
677         kfree(file->private_data);
678         file->private_data = NULL;
679         return 0;
680 }
681
682 static loff_t usb_device_lseek(struct file *file, loff_t offset, int orig)
683 {
684         loff_t ret;
685
686         lock_kernel();
687
688         switch (orig) {
689         case 0:
690                 file->f_pos = offset;
691                 ret = file->f_pos;
692                 break;
693         case 1:
694                 file->f_pos += offset;
695                 ret = file->f_pos;
696                 break;
697         case 2:
698         default:
699                 ret = -EINVAL;
700         }
701
702         unlock_kernel();
703         return ret;
704 }
705
706 const struct file_operations usbfs_devices_fops = {
707         .llseek =       usb_device_lseek,
708         .read =         usb_device_read,
709         .poll =         usb_device_poll,
710         .open =         usb_device_open,
711         .release =      usb_device_release,
712 };