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>.
   5  *     (proc file per device)
   6  * (C) Copyright 1999 Deti Fliegl (new USB architecture)
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  21  *
  22  *************************************************************
  23  *
  24  * <mountpoint>/devices contains USB topology, device, config, class,
  25  * interface, & endpoint data.
  26  *
  27  * I considered using /proc/bus/usb/devices/device# for each device
  28  * as it is attached or detached, but I didn't like this for some
  29  * reason -- maybe it's just too deep of a directory structure.
  30  * I also don't like looking in multiple places to gather and view
  31  * the data.  Having only one file for ./devices also prevents race
  32  * conditions that could arise if a program was reading device info
  33  * for devices that are being removed (unplugged).  (That is, the
  34  * program may find a directory for devnum_12 then try to open it,
  35  * but it was just unplugged, so the directory is now deleted.
  36  * But programs would just have to be prepared for situations like
  37  * this in any plug-and-play environment.)
  38  *
  39  * 1999-12-16: Thomas Sailer <sailer@ife.ee.ethz.ch>
  40  *   Converted the whole proc stuff to real
  41  *   read methods. Now not the whole device list needs to fit
  42  *   into one page, only the device list for one bus.
  43  *   Added a poll method to /proc/bus/usb/devices, to wake
  44  *   up an eventual usbd
  45  * 2000-01-04: Thomas Sailer <sailer@ife.ee.ethz.ch>
  46  *   Turned into its own filesystem
  47  * 2000-07-05: Ashley Montanaro <ashley@compsoc.man.ac.uk>
  48  *   Converted file reading routine to dump to buffer once
  49  *   per device, not per bus
  50  */
  51
  52 #include <linux/fs.h>
  53 #include <linux/mm.h>
  54 #include <linux/gfp.h>
  55 #include <linux/poll.h>
  56 #include <linux/usb.h>
  57 #include <linux/usbdevice_fs.h>
  58 #include <linux/usb/hcd.h>
  59 #include <linux/mutex.h>
  60 #include <linux/uaccess.h>
  61
  62 #include "usb.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=dddd MxCh=dd */
  69 "\nT:  Bus=%2.2d Lev=%2.2d Prnt=%2.2d Port=%2.2d Cnt=%2.2d Dev#=%3d Spd=%-4s 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 /*
 121  * Wait for an connect/disconnect event to happen. We initialize
 122  * the event counter with an odd number, and each event will increment
 123  * the event counter by two, so it will always _stay_ odd. That means
 124  * that it will never be zero, so "event 0" will never match a current
 125  * event, and thus 'poll' will always trigger as readable for the first
 126  * time it gets called.
 127  */
 128 static struct device_connect_event {
 129         atomic_t count;
 130         wait_queue_head_t wait;
 131 } device_event = {
 132         .count = ATOMIC_INIT(1),
 133         .wait = __WAIT_QUEUE_HEAD_INITIALIZER(device_event.wait)
 134 };
 135
 136 struct class_info {
 137         int class;
 138         char *class_name;
 139 };
 140
 141 static const struct class_info clas_info[] = {
 142         /* max. 5 chars. per name string */
 143         {USB_CLASS_PER_INTERFACE,       ">ifc"},
 144         {USB_CLASS_AUDIO,               "audio"},
 145         {USB_CLASS_COMM,                "comm."},
 146         {USB_CLASS_HID,                 "HID"},
 147         {USB_CLASS_PHYSICAL,            "PID"},
 148         {USB_CLASS_STILL_IMAGE,         "still"},
 149         {USB_CLASS_PRINTER,             "print"},
 150         {USB_CLASS_MASS_STORAGE,        "stor."},
 151         {USB_CLASS_HUB,                 "hub"},
 152         {USB_CLASS_CDC_DATA,            "data"},
 153         {USB_CLASS_CSCID,               "scard"},
 154         {USB_CLASS_CONTENT_SEC,         "c-sec"},
 155         {USB_CLASS_VIDEO,               "video"},
 156         {USB_CLASS_WIRELESS_CONTROLLER, "wlcon"},
 157         {USB_CLASS_MISC,                "misc"},
 158         {USB_CLASS_APP_SPEC,            "app."},
 159         {USB_CLASS_VENDOR_SPEC,         "vend."},
 160         {-1,                            "unk."}         /* leave as last */
 161 };
 162
 163 /*****************************************************************/
 164
 165 void usbfs_conn_disc_event(void)
 166 {
 167         atomic_add(2, &device_event.count);
 168         wake_up(&device_event.wait);
 169 }
 170
 171 static const char *class_decode(const int class)
 172 {
 173         int ix;
 174
 175         for (ix = 0; clas_info[ix].class != -1; ix++)
 176                 if (clas_info[ix].class == class)
 177                         break;
 178         return clas_info[ix].class_name;
 179 }
 180
 181 static char *usb_dump_endpoint_descriptor(int speed, char *start, char *end,
 182                                 const struct usb_endpoint_descriptor *desc)
 183 {
 184         char dir, unit, *type;
 185         unsigned interval, bandwidth = 1;
 186
 187         if (start > end)
 188                 return start;
 189
 190         dir = usb_endpoint_dir_in(desc) ? 'I' : 'O';
 191
 192         if (speed == USB_SPEED_HIGH) {
 193                 switch (usb_endpoint_maxp(desc) & (0x03 << 11)) {
 194                 case 1 << 11:
 195                         bandwidth = 2; break;
 196                 case 2 << 11:
 197                         bandwidth = 3; break;
 198                 }
 199         }
 200
 201         /* this isn't checking for illegal values */
 202         switch (usb_endpoint_type(desc)) {
 203         case USB_ENDPOINT_XFER_CONTROL:
 204                 type = "Ctrl";
 205                 if (speed == USB_SPEED_HIGH)    /* uframes per NAK */
 206                         interval = desc->bInterval;
 207                 else
 208                         interval = 0;
 209                 dir = 'B';                      /* ctrl is bidirectional */
 210                 break;
 211         case USB_ENDPOINT_XFER_ISOC:
 212                 type = "Isoc";
 213                 interval = 1 << (desc->bInterval - 1);
 214                 break;
 215         case USB_ENDPOINT_XFER_BULK:
 216                 type = "Bulk";
 217                 if (speed == USB_SPEED_HIGH && dir == 'O') /* uframes per NAK */
 218                         interval = desc->bInterval;
 219                 else
 220                         interval = 0;
 221                 break;
 222         case USB_ENDPOINT_XFER_INT:
 223                 type = "Int.";
 224                 if (speed == USB_SPEED_HIGH || speed == USB_SPEED_SUPER)
 225                         interval = 1 << (desc->bInterval - 1);
 226                 else
 227                         interval = desc->bInterval;
 228                 break;
 229         default:        /* "can't happen" */
 230                 return start;
 231         }
 232         interval *= (speed == USB_SPEED_HIGH ||
 233                      speed == USB_SPEED_SUPER) ? 125 : 1000;
 234         if (interval % 1000)
 235                 unit = 'u';
 236         else {
 237                 unit = 'm';
 238                 interval /= 1000;
 239         }
 240
 241         start += sprintf(start, format_endpt, desc->bEndpointAddress, dir,
 242                          desc->bmAttributes, type,
 243                          (usb_endpoint_maxp(desc) & 0x07ff) *
 244                          bandwidth,
 245                          interval, unit);
 246         return start;
 247 }
 248
 249 static char *usb_dump_interface_descriptor(char *start, char *end,
 250                                         const struct usb_interface_cache *intfc,
 251                                         const struct usb_interface *iface,
 252                                         int setno)
 253 {
 254         const struct usb_interface_descriptor *desc;
 255         const char *driver_name = "";
 256         int active = 0;
 257
 258         if (start > end)
 259                 return start;
 260         desc = &intfc->altsetting[setno].desc;
 261         if (iface) {
 262                 driver_name = (iface->dev.driver
 263                                 ? iface->dev.driver->name
 264                                 : "(none)");
 265                 active = (desc == &iface->cur_altsetting->desc);
 266         }
 267         start += sprintf(start, format_iface,
 268                          active ? '*' : ' ',    /* mark active altsetting */
 269                          desc->bInterfaceNumber,
 270                          desc->bAlternateSetting,
 271                          desc->bNumEndpoints,
 272                          desc->bInterfaceClass,
 273                          class_decode(desc->bInterfaceClass),
 274                          desc->bInterfaceSubClass,
 275                          desc->bInterfaceProtocol,
 276                          driver_name);
 277         return start;
 278 }
 279
 280 static char *usb_dump_interface(int speed, char *start, char *end,
 281                                 const struct usb_interface_cache *intfc,
 282                                 const struct usb_interface *iface, int setno)
 283 {
 284         const struct usb_host_interface *desc = &intfc->altsetting[setno];
 285         int i;
 286
 287         start = usb_dump_interface_descriptor(start, end, intfc, iface, setno);
 288         for (i = 0; i < desc->desc.bNumEndpoints; i++) {
 289                 if (start > end)
 290                         return start;
 291                 start = usb_dump_endpoint_descriptor(speed,
 292                                 start, end, &desc->endpoint[i].desc);
 293         }
 294         return start;
 295 }
 296
 297 static char *usb_dump_iad_descriptor(char *start, char *end,
 298                         const struct usb_interface_assoc_descriptor *iad)
 299 {
 300         if (start > end)
 301                 return start;
 302         start += sprintf(start, format_iad,
 303                          iad->bFirstInterface,
 304                          iad->bInterfaceCount,
 305                          iad->bFunctionClass,
 306                          class_decode(iad->bFunctionClass),
 307                          iad->bFunctionSubClass,
 308                          iad->bFunctionProtocol);
 309         return start;
 310 }
 311
 312 /* TBD:
 313  * 0. TBDs
 314  * 1. marking active interface altsettings (code lists all, but should mark
 315  *    which ones are active, if any)
 316  */
 317 static char *usb_dump_config_descriptor(char *start, char *end,
 318                                 const struct usb_config_descriptor *desc,
 319                                 int active)
 320 {
 321         if (start > end)
 322                 return start;
 323         start += sprintf(start, format_config,
 324                          /* mark active/actual/current cfg. */
 325                          active ? '*' : ' ',
 326                          desc->bNumInterfaces,
 327                          desc->bConfigurationValue,
 328                          desc->bmAttributes,
 329                          desc->bMaxPower * 2);
 330         return start;
 331 }
 332
 333 static char *usb_dump_config(int speed, char *start, char *end,
 334                              const struct usb_host_config *config, int active)
 335 {
 336         int i, j;
 337         struct usb_interface_cache *intfc;
 338         struct usb_interface *interface;
 339
 340         if (start > end)
 341                 return start;
 342         if (!config)
 343                 /* getting these some in 2.3.7; none in 2.3.6 */
 344                 return start + sprintf(start, "(null Cfg. desc.)\n");
 345         start = usb_dump_config_descriptor(start, end, &config->desc, active);
 346         for (i = 0; i < USB_MAXIADS; i++) {
 347                 if (config->intf_assoc[i] == NULL)
 348                         break;
 349                 start = usb_dump_iad_descriptor(start, end,
 350                                         config->intf_assoc[i]);
 351         }
 352         for (i = 0; i < config->desc.bNumInterfaces; i++) {
 353                 intfc = config->intf_cache[i];
 354                 interface = config->interface[i];
 355                 for (j = 0; j < intfc->num_altsetting; j++) {
 356                         if (start > end)
 357                                 return start;
 358                         start = usb_dump_interface(speed,
 359                                 start, end, intfc, interface, j);
 360                 }
 361         }
 362         return start;
 363 }
 364
 365 /*
 366  * Dump the different USB descriptors.
 367  */
 368 static char *usb_dump_device_descriptor(char *start, char *end,
 369                                 const struct usb_device_descriptor *desc)
 370 {
 371         u16 bcdUSB = le16_to_cpu(desc->bcdUSB);
 372         u16 bcdDevice = le16_to_cpu(desc->bcdDevice);
 373
 374         if (start > end)
 375                 return start;
 376         start += sprintf(start, format_device1,
 377                           bcdUSB >> 8, bcdUSB & 0xff,
 378                           desc->bDeviceClass,
 379                           class_decode(desc->bDeviceClass),
 380                           desc->bDeviceSubClass,
 381                           desc->bDeviceProtocol,
 382                           desc->bMaxPacketSize0,
 383                           desc->bNumConfigurations);
 384         if (start > end)
 385                 return start;
 386         start += sprintf(start, format_device2,
 387                          le16_to_cpu(desc->idVendor),
 388                          le16_to_cpu(desc->idProduct),
 389                          bcdDevice >> 8, bcdDevice & 0xff);
 390         return start;
 391 }
 392
 393 /*
 394  * Dump the different strings that this device holds.
 395  */
 396 static char *usb_dump_device_strings(char *start, char *end,
 397                                      struct usb_device *dev)
 398 {
 399         if (start > end)
 400                 return start;
 401         if (dev->manufacturer)
 402                 start += sprintf(start, format_string_manufacturer,
 403                                  dev->manufacturer);
 404         if (start > end)
 405                 goto out;
 406         if (dev->product)
 407                 start += sprintf(start, format_string_product, dev->product);
 408         if (start > end)
 409                 goto out;
 410 #ifdef ALLOW_SERIAL_NUMBER
 411         if (dev->serial)
 412                 start += sprintf(start, format_string_serialnumber,
 413                                  dev->serial);
 414 #endif
 415  out:
 416         return start;
 417 }
 418
 419 static char *usb_dump_desc(char *start, char *end, struct usb_device *dev)
 420 {
 421         int i;
 422
 423         if (start > end)
 424                 return start;
 425
 426         start = usb_dump_device_descriptor(start, end, &dev->descriptor);
 427
 428         if (start > end)
 429                 return start;
 430
 431         start = usb_dump_device_strings(start, end, dev);
 432
 433         for (i = 0; i < dev->descriptor.bNumConfigurations; i++) {
 434                 if (start > end)
 435                         return start;
 436                 start = usb_dump_config(dev->speed,
 437                                 start, end, dev->config + i,
 438                                 /* active ? */
 439                                 (dev->config + i) == dev->actconfig);
 440         }
 441         return start;
 442 }
 443
 444
 445 #ifdef PROC_EXTRA /* TBD: may want to add this code later */
 446
 447 static char *usb_dump_hub_descriptor(char *start, char *end,
 448                                      const struct usb_hub_descriptor *desc)
 449 {
 450         int leng = USB_DT_HUB_NONVAR_SIZE;
 451         unsigned char *ptr = (unsigned char *)desc;
 452
 453         if (start > end)
 454                 return start;
 455         start += sprintf(start, "Interface:");
 456         while (leng && start <= end) {
 457                 start += sprintf(start, " %02x", *ptr);
 458                 ptr++; leng--;
 459         }
 460         *start++ = '\n';
 461         return start;
 462 }
 463
 464 static char *usb_dump_string(char *start, char *end,
 465                              const struct usb_device *dev, char *id, int index)
 466 {
 467         if (start > end)
 468                 return start;
 469         start += sprintf(start, "Interface:");
 470         if (index <= dev->maxstring && dev->stringindex &&
 471             dev->stringindex[index])
 472                 start += sprintf(start, "%s: %.100s ", id,
 473                                  dev->stringindex[index]);
 474         return start;
 475 }
 476
 477 #endif /* PROC_EXTRA */
 478
 479 /*****************************************************************/
 480
 481 /* This is a recursive function. Parameters:
 482  * buffer - the user-space buffer to write data into
 483  * nbytes - the maximum number of bytes to write
 484  * skip_bytes - the number of bytes to skip before writing anything
 485  * file_offset - the offset into the devices file on completion
 486  * The caller must own the device lock.
 487  */
 488 static ssize_t usb_device_dump(char __user **buffer, size_t *nbytes,
 489                                loff_t *skip_bytes, loff_t *file_offset,
 490                                struct usb_device *usbdev, struct usb_bus *bus,
 491                                int level, int index, int count)
 492 {
 493         int chix;
 494         int ret, cnt = 0;
 495         int parent_devnum = 0;
 496         char *pages_start, *data_end, *speed;
 497         unsigned int length;
 498         ssize_t total_written = 0;
 499
 500         /* don't bother with anything else if we're not writing any data */
 501         if (*nbytes <= 0)
 502                 return 0;
 503
 504         if (level > MAX_TOPO_LEVEL)
 505                 return 0;
 506         /* allocate 2^1 pages = 8K (on i386);
 507          * should be more than enough for one device */
 508         pages_start = (char *)__get_free_pages(GFP_NOIO, 1);
 509         if (!pages_start)
 510                 return -ENOMEM;
 511
 512         if (usbdev->parent && usbdev->parent->devnum != -1)
 513                 parent_devnum = usbdev->parent->devnum;
 514         /*
 515          * So the root hub's parent is 0 and any device that is
 516          * plugged into the root hub has a parent of 0.
 517          */
 518         switch (usbdev->speed) {
 519         case USB_SPEED_LOW:
 520                 speed = "1.5"; break;
 521         case USB_SPEED_UNKNOWN:         /* usb 1.1 root hub code */
 522         case USB_SPEED_FULL:
 523                 speed = "12"; break;
 524         case USB_SPEED_WIRELESS:        /* Wireless has no real fixed speed */
 525         case USB_SPEED_HIGH:
 526                 speed = "480"; break;
 527         case USB_SPEED_SUPER:
 528                 speed = "5000"; break;
 529         default:
 530                 speed = "??";
 531         }
 532         data_end = pages_start + sprintf(pages_start, format_topo,
 533                         bus->busnum, level, parent_devnum,
 534                         index, count, usbdev->devnum,
 535                         speed, usbdev->maxchild);
 536         /*
 537          * level = topology-tier level;
 538          * parent_devnum = parent device number;
 539          * index = parent's connector number;
 540          * count = device count at this level
 541          */
 542         /* If this is the root hub, display the bandwidth information */
 543         if (level == 0) {
 544                 int     max;
 545
 546                 /* super/high speed reserves 80%, full/low reserves 90% */
 547                 if (usbdev->speed == USB_SPEED_HIGH ||
 548                     usbdev->speed == USB_SPEED_SUPER)
 549                         max = 800;
 550                 else
 551                         max = FRAME_TIME_MAX_USECS_ALLOC;
 552
 553                 /* report "average" periodic allocation over a microsecond.
 554                  * the schedules are actually bursty, HCDs need to deal with
 555                  * that and just compute/report this average.
 556                  */
 557                 data_end += sprintf(data_end, format_bandwidth,
 558                                 bus->bandwidth_allocated, max,
 559                                 (100 * bus->bandwidth_allocated + max / 2)
 560                                         / max,
 561                                 bus->bandwidth_int_reqs,
 562                                 bus->bandwidth_isoc_reqs);
 563
 564         }
 565         data_end = usb_dump_desc(data_end, pages_start + (2 * PAGE_SIZE) - 256,
 566                                  usbdev);
 567
 568         if (data_end > (pages_start + (2 * PAGE_SIZE) - 256))
 569                 data_end += sprintf(data_end, "(truncated)\n");
 570
 571         length = data_end - pages_start;
 572         /* if we can start copying some data to the user */
 573         if (length > *skip_bytes) {
 574                 length -= *skip_bytes;
 575                 if (length > *nbytes)
 576                         length = *nbytes;
 577                 if (copy_to_user(*buffer, pages_start + *skip_bytes, length)) {
 578                         free_pages((unsigned long)pages_start, 1);
 579                         return -EFAULT;
 580                 }
 581                 *nbytes -= length;
 582                 *file_offset += length;
 583                 total_written += length;
 584                 *buffer += length;
 585                 *skip_bytes = 0;
 586         } else
 587                 *skip_bytes -= length;
 588
 589         free_pages((unsigned long)pages_start, 1);
 590
 591         /* Now look at all of this device's children. */
 592         for (chix = 0; chix < usbdev->maxchild; chix++) {
 593                 struct usb_device *childdev = usbdev->children[chix];
 594
 595                 if (childdev) {
 596                         usb_lock_device(childdev);
 597                         ret = usb_device_dump(buffer, nbytes, skip_bytes,
 598                                               file_offset, childdev, bus,
 599                                               level + 1, chix, ++cnt);
 600                         usb_unlock_device(childdev);
 601                         if (ret == -EFAULT)
 602                                 return total_written;
 603                         total_written += ret;
 604                 }
 605         }
 606         return total_written;
 607 }
 608
 609 static ssize_t usb_device_read(struct file *file, char __user *buf,
 610                                size_t nbytes, loff_t *ppos)
 611 {
 612         struct usb_bus *bus;
 613         ssize_t ret, total_written = 0;
 614         loff_t skip_bytes = *ppos;
 615
 616         if (*ppos < 0)
 617                 return -EINVAL;
 618         if (nbytes <= 0)
 619                 return 0;
 620         if (!access_ok(VERIFY_WRITE, buf, nbytes))
 621                 return -EFAULT;
 622
 623         mutex_lock(&usb_bus_list_lock);
 624         /* print devices for all busses */
 625         list_for_each_entry(bus, &usb_bus_list, bus_list) {
 626                 /* recurse through all children of the root hub */
 627                 if (!bus_to_hcd(bus)->rh_registered)
 628                         continue;
 629                 usb_lock_device(bus->root_hub);
 630                 ret = usb_device_dump(&buf, &nbytes, &skip_bytes, ppos,
 631                                       bus->root_hub, bus, 0, 0, 0);
 632                 usb_unlock_device(bus->root_hub);
 633                 if (ret < 0) {
 634                         mutex_unlock(&usb_bus_list_lock);
 635                         return ret;
 636                 }
 637                 total_written += ret;
 638         }
 639         mutex_unlock(&usb_bus_list_lock);
 640         return total_written;
 641 }
 642
 643 /* Kernel lock for "lastev" protection */
 644 static unsigned int usb_device_poll(struct file *file,
 645                                     struct poll_table_struct *wait)
 646 {
 647         unsigned int event_count;
 648
 649         poll_wait(file, &device_event.wait, wait);
 650
 651         event_count = atomic_read(&device_event.count);
 652         if (file->f_version != event_count) {
 653                 file->f_version = event_count;
 654                 return POLLIN | POLLRDNORM;
 655         }
 656
 657         return 0;
 658 }
 659
 660 static loff_t usb_device_lseek(struct file *file, loff_t offset, int orig)
 661 {
 662         loff_t ret;
 663
 664         mutex_lock(&file->f_dentry->d_inode->i_mutex);
 665
 666         switch (orig) {
 667         case 0:
 668                 file->f_pos = offset;
 669                 ret = file->f_pos;
 670                 break;
 671         case 1:
 672                 file->f_pos += offset;
 673                 ret = file->f_pos;
 674                 break;
 675         case 2:
 676         default:
 677                 ret = -EINVAL;
 678         }
 679
 680         mutex_unlock(&file->f_dentry->d_inode->i_mutex);
 681         return ret;
 682 }
 683
 684 const struct file_operations usbfs_devices_fops = {
 685         .llseek =       usb_device_lseek,
 686         .read =         usb_device_read,
 687         .poll =         usb_device_poll,
 688 };