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 (le16_to_cpu(desc->wMaxPacketSize) & (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)
 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) ? 125 : 1000;
 233         if (interval % 1000)
 234                 unit = 'u';
 235         else {
 236                 unit = 'm';
 237                 interval /= 1000;
 238         }
 239
 240         start += sprintf(start, format_endpt, desc->bEndpointAddress, dir,
 241                          desc->bmAttributes, type,
 242                          (le16_to_cpu(desc->wMaxPacketSize) & 0x07ff) *
 243                          bandwidth,
 244                          interval, unit);
 245         return start;
 246 }
 247
 248 static char *usb_dump_interface_descriptor(char *start, char *end,
 249                                         const struct usb_interface_cache *intfc,
 250                                         const struct usb_interface *iface,
 251                                         int setno)
 252 {
 253         const struct usb_interface_descriptor *desc;
 254         const char *driver_name = "";
 255         int active = 0;
 256
 257         if (start > end)
 258                 return start;
 259         desc = &intfc->altsetting[setno].desc;
 260         if (iface) {
 261                 driver_name = (iface->dev.driver
 262                                 ? iface->dev.driver->name
 263                                 : "(none)");
 264                 active = (desc == &iface->cur_altsetting->desc);
 265         }
 266         start += sprintf(start, format_iface,
 267                          active ? '*' : ' ',    /* mark active altsetting */
 268                          desc->bInterfaceNumber,
 269                          desc->bAlternateSetting,
 270                          desc->bNumEndpoints,
 271                          desc->bInterfaceClass,
 272                          class_decode(desc->bInterfaceClass),
 273                          desc->bInterfaceSubClass,
 274                          desc->bInterfaceProtocol,
 275                          driver_name);
 276         return start;
 277 }
 278
 279 static char *usb_dump_interface(int speed, char *start, char *end,
 280                                 const struct usb_interface_cache *intfc,
 281                                 const struct usb_interface *iface, int setno)
 282 {
 283         const struct usb_host_interface *desc = &intfc->altsetting[setno];
 284         int i;
 285
 286         start = usb_dump_interface_descriptor(start, end, intfc, iface, setno);
 287         for (i = 0; i < desc->desc.bNumEndpoints; i++) {
 288                 if (start > end)
 289                         return start;
 290                 start = usb_dump_endpoint_descriptor(speed,
 291                                 start, end, &desc->endpoint[i].desc);
 292         }
 293         return start;
 294 }
 295
 296 static char *usb_dump_iad_descriptor(char *start, char *end,
 297                         const struct usb_interface_assoc_descriptor *iad)
 298 {
 299         if (start > end)
 300                 return start;
 301         start += sprintf(start, format_iad,
 302                          iad->bFirstInterface,
 303                          iad->bInterfaceCount,
 304                          iad->bFunctionClass,
 305                          class_decode(iad->bFunctionClass),
 306                          iad->bFunctionSubClass,
 307                          iad->bFunctionProtocol);
 308         return start;
 309 }
 310
 311 /* TBD:
 312  * 0. TBDs
 313  * 1. marking active interface altsettings (code lists all, but should mark
 314  *    which ones are active, if any)
 315  */
 316 static char *usb_dump_config_descriptor(char *start, char *end,
 317                                 const struct usb_config_descriptor *desc,
 318                                 int active)
 319 {
 320         if (start > end)
 321                 return start;
 322         start += sprintf(start, format_config,
 323                          /* mark active/actual/current cfg. */
 324                          active ? '*' : ' ',
 325                          desc->bNumInterfaces,
 326                          desc->bConfigurationValue,
 327                          desc->bmAttributes,
 328                          desc->bMaxPower * 2);
 329         return start;
 330 }
 331
 332 static char *usb_dump_config(int speed, char *start, char *end,
 333                              const struct usb_host_config *config, int active)
 334 {
 335         int i, j;
 336         struct usb_interface_cache *intfc;
 337         struct usb_interface *interface;
 338
 339         if (start > end)
 340                 return start;
 341         if (!config)
 342                 /* getting these some in 2.3.7; none in 2.3.6 */
 343                 return start + sprintf(start, "(null Cfg. desc.)\n");
 344         start = usb_dump_config_descriptor(start, end, &config->desc, active);
 345         for (i = 0; i < USB_MAXIADS; i++) {
 346                 if (config->intf_assoc[i] == NULL)
 347                         break;
 348                 start = usb_dump_iad_descriptor(start, end,
 349                                         config->intf_assoc[i]);
 350         }
 351         for (i = 0; i < config->desc.bNumInterfaces; i++) {
 352                 intfc = config->intf_cache[i];
 353                 interface = config->interface[i];
 354                 for (j = 0; j < intfc->num_altsetting; j++) {
 355                         if (start > end)
 356                                 return start;
 357                         start = usb_dump_interface(speed,
 358                                 start, end, intfc, interface, j);
 359                 }
 360         }
 361         return start;
 362 }
 363
 364 /*
 365  * Dump the different USB descriptors.
 366  */
 367 static char *usb_dump_device_descriptor(char *start, char *end,
 368                                 const struct usb_device_descriptor *desc)
 369 {
 370         u16 bcdUSB = le16_to_cpu(desc->bcdUSB);
 371         u16 bcdDevice = le16_to_cpu(desc->bcdDevice);
 372
 373         if (start > end)
 374                 return start;
 375         start += sprintf(start, format_device1,
 376                           bcdUSB >> 8, bcdUSB & 0xff,
 377                           desc->bDeviceClass,
 378                           class_decode(desc->bDeviceClass),
 379                           desc->bDeviceSubClass,
 380                           desc->bDeviceProtocol,
 381                           desc->bMaxPacketSize0,
 382                           desc->bNumConfigurations);
 383         if (start > end)
 384                 return start;
 385         start += sprintf(start, format_device2,
 386                          le16_to_cpu(desc->idVendor),
 387                          le16_to_cpu(desc->idProduct),
 388                          bcdDevice >> 8, bcdDevice & 0xff);
 389         return start;
 390 }
 391
 392 /*
 393  * Dump the different strings that this device holds.
 394  */
 395 static char *usb_dump_device_strings(char *start, char *end,
 396                                      struct usb_device *dev)
 397 {
 398         if (start > end)
 399                 return start;
 400         if (dev->manufacturer)
 401                 start += sprintf(start, format_string_manufacturer,
 402                                  dev->manufacturer);
 403         if (start > end)
 404                 goto out;
 405         if (dev->product)
 406                 start += sprintf(start, format_string_product, dev->product);
 407         if (start > end)
 408                 goto out;
 409 #ifdef ALLOW_SERIAL_NUMBER
 410         if (dev->serial)
 411                 start += sprintf(start, format_string_serialnumber,
 412                                  dev->serial);
 413 #endif
 414  out:
 415         return start;
 416 }
 417
 418 static char *usb_dump_desc(char *start, char *end, struct usb_device *dev)
 419 {
 420         int i;
 421
 422         if (start > end)
 423                 return start;
 424
 425         start = usb_dump_device_descriptor(start, end, &dev->descriptor);
 426
 427         if (start > end)
 428                 return start;
 429
 430         start = usb_dump_device_strings(start, end, dev);
 431
 432         for (i = 0; i < dev->descriptor.bNumConfigurations; i++) {
 433                 if (start > end)
 434                         return start;
 435                 start = usb_dump_config(dev->speed,
 436                                 start, end, dev->config + i,
 437                                 /* active ? */
 438                                 (dev->config + i) == dev->actconfig);
 439         }
 440         return start;
 441 }
 442
 443
 444 #ifdef PROC_EXTRA /* TBD: may want to add this code later */
 445
 446 static char *usb_dump_hub_descriptor(char *start, char *end,
 447                                      const struct usb_hub_descriptor *desc)
 448 {
 449         int leng = USB_DT_HUB_NONVAR_SIZE;
 450         unsigned char *ptr = (unsigned char *)desc;
 451
 452         if (start > end)
 453                 return start;
 454         start += sprintf(start, "Interface:");
 455         while (leng && start <= end) {
 456                 start += sprintf(start, " %02x", *ptr);
 457                 ptr++; leng--;
 458         }
 459         *start++ = '\n';
 460         return start;
 461 }
 462
 463 static char *usb_dump_string(char *start, char *end,
 464                              const struct usb_device *dev, char *id, int index)
 465 {
 466         if (start > end)
 467                 return start;
 468         start += sprintf(start, "Interface:");
 469         if (index <= dev->maxstring && dev->stringindex &&
 470             dev->stringindex[index])
 471                 start += sprintf(start, "%s: %.100s ", id,
 472                                  dev->stringindex[index]);
 473         return start;
 474 }
 475
 476 #endif /* PROC_EXTRA */
 477
 478 /*****************************************************************/
 479
 480 /* This is a recursive function. Parameters:
 481  * buffer - the user-space buffer to write data into
 482  * nbytes - the maximum number of bytes to write
 483  * skip_bytes - the number of bytes to skip before writing anything
 484  * file_offset - the offset into the devices file on completion
 485  * The caller must own the device lock.
 486  */
 487 static ssize_t usb_device_dump(char __user **buffer, size_t *nbytes,
 488                                loff_t *skip_bytes, loff_t *file_offset,
 489                                struct usb_device *usbdev, struct usb_bus *bus,
 490                                int level, int index, int count)
 491 {
 492         int chix;
 493         int ret, cnt = 0;
 494         int parent_devnum = 0;
 495         char *pages_start, *data_end, *speed;
 496         unsigned int length;
 497         ssize_t total_written = 0;
 498
 499         /* don't bother with anything else if we're not writing any data */
 500         if (*nbytes <= 0)
 501                 return 0;
 502
 503         if (level > MAX_TOPO_LEVEL)
 504                 return 0;
 505         /* allocate 2^1 pages = 8K (on i386);
 506          * should be more than enough for one device */
 507         pages_start = (char *)__get_free_pages(GFP_NOIO, 1);
 508         if (!pages_start)
 509                 return -ENOMEM;
 510
 511         if (usbdev->parent && usbdev->parent->devnum != -1)
 512                 parent_devnum = usbdev->parent->devnum;
 513         /*
 514          * So the root hub's parent is 0 and any device that is
 515          * plugged into the root hub has a parent of 0.
 516          */
 517         switch (usbdev->speed) {
 518         case USB_SPEED_LOW:
 519                 speed = "1.5"; break;
 520         case USB_SPEED_UNKNOWN:         /* usb 1.1 root hub code */
 521         case USB_SPEED_FULL:
 522                 speed = "12"; break;
 523         case USB_SPEED_WIRELESS:        /* Wireless has no real fixed speed */
 524         case USB_SPEED_HIGH:
 525                 speed = "480"; break;
 526         case USB_SPEED_SUPER:
 527                 speed = "5000"; break;
 528         default:
 529                 speed = "??";
 530         }
 531         data_end = pages_start + sprintf(pages_start, format_topo,
 532                         bus->busnum, level, parent_devnum,
 533                         index, count, usbdev->devnum,
 534                         speed, usbdev->maxchild);
 535         /*
 536          * level = topology-tier level;
 537          * parent_devnum = parent device number;
 538          * index = parent's connector number;
 539          * count = device count at this level
 540          */
 541         /* If this is the root hub, display the bandwidth information */
 542         if (level == 0) {
 543                 int     max;
 544
 545                 /* high speed reserves 80%, full/low reserves 90% */
 546                 if (usbdev->speed == USB_SPEED_HIGH)
 547                         max = 800;
 548                 else
 549                         max = FRAME_TIME_MAX_USECS_ALLOC;
 550
 551                 /* report "average" periodic allocation over a microsecond.
 552                  * the schedules are actually bursty, HCDs need to deal with
 553                  * that and just compute/report this average.
 554                  */
 555                 data_end += sprintf(data_end, format_bandwidth,
 556                                 bus->bandwidth_allocated, max,
 557                                 (100 * bus->bandwidth_allocated + max / 2)
 558                                         / max,
 559                                 bus->bandwidth_int_reqs,
 560                                 bus->bandwidth_isoc_reqs);
 561
 562         }
 563         data_end = usb_dump_desc(data_end, pages_start + (2 * PAGE_SIZE) - 256,
 564                                  usbdev);
 565
 566         if (data_end > (pages_start + (2 * PAGE_SIZE) - 256))
 567                 data_end += sprintf(data_end, "(truncated)\n");
 568
 569         length = data_end - pages_start;
 570         /* if we can start copying some data to the user */
 571         if (length > *skip_bytes) {
 572                 length -= *skip_bytes;
 573                 if (length > *nbytes)
 574                         length = *nbytes;
 575                 if (copy_to_user(*buffer, pages_start + *skip_bytes, length)) {
 576                         free_pages((unsigned long)pages_start, 1);
 577                         return -EFAULT;
 578                 }
 579                 *nbytes -= length;
 580                 *file_offset += length;
 581                 total_written += length;
 582                 *buffer += length;
 583                 *skip_bytes = 0;
 584         } else
 585                 *skip_bytes -= length;
 586
 587         free_pages((unsigned long)pages_start, 1);
 588
 589         /* Now look at all of this device's children. */
 590         for (chix = 0; chix < usbdev->maxchild; chix++) {
 591                 struct usb_device *childdev = usbdev->children[chix];
 592
 593                 if (childdev) {
 594                         usb_lock_device(childdev);
 595                         ret = usb_device_dump(buffer, nbytes, skip_bytes,
 596                                               file_offset, childdev, bus,
 597                                               level + 1, chix, ++cnt);
 598                         usb_unlock_device(childdev);
 599                         if (ret == -EFAULT)
 600                                 return total_written;
 601                         total_written += ret;
 602                 }
 603         }
 604         return total_written;
 605 }
 606
 607 static ssize_t usb_device_read(struct file *file, char __user *buf,
 608                                size_t nbytes, loff_t *ppos)
 609 {
 610         struct usb_bus *bus;
 611         ssize_t ret, total_written = 0;
 612         loff_t skip_bytes = *ppos;
 613
 614         if (*ppos < 0)
 615                 return -EINVAL;
 616         if (nbytes <= 0)
 617                 return 0;
 618         if (!access_ok(VERIFY_WRITE, buf, nbytes))
 619                 return -EFAULT;
 620
 621         mutex_lock(&usb_bus_list_lock);
 622         /* print devices for all busses */
 623         list_for_each_entry(bus, &usb_bus_list, bus_list) {
 624                 /* recurse through all children of the root hub */
 625                 if (!bus->root_hub)
 626                         continue;
 627                 usb_lock_device(bus->root_hub);
 628                 ret = usb_device_dump(&buf, &nbytes, &skip_bytes, ppos,
 629                                       bus->root_hub, bus, 0, 0, 0);
 630                 usb_unlock_device(bus->root_hub);
 631                 if (ret < 0) {
 632                         mutex_unlock(&usb_bus_list_lock);
 633                         return ret;
 634                 }
 635                 total_written += ret;
 636         }
 637         mutex_unlock(&usb_bus_list_lock);
 638         return total_written;
 639 }
 640
 641 /* Kernel lock for "lastev" protection */
 642 static unsigned int usb_device_poll(struct file *file,
 643                                     struct poll_table_struct *wait)
 644 {
 645         unsigned int event_count;
 646
 647         poll_wait(file, &device_event.wait, wait);
 648
 649         event_count = atomic_read(&device_event.count);
 650         if (file->f_version != event_count) {
 651                 file->f_version = event_count;
 652                 return POLLIN | POLLRDNORM;
 653         }
 654
 655         return 0;
 656 }
 657
 658 static loff_t usb_device_lseek(struct file *file, loff_t offset, int orig)
 659 {
 660         loff_t ret;
 661
 662         mutex_lock(&file->f_dentry->d_inode->i_mutex);
 663
 664         switch (orig) {
 665         case 0:
 666                 file->f_pos = offset;
 667                 ret = file->f_pos;
 668                 break;
 669         case 1:
 670                 file->f_pos += offset;
 671                 ret = file->f_pos;
 672                 break;
 673         case 2:
 674         default:
 675                 ret = -EINVAL;
 676         }
 677
 678         mutex_unlock(&file->f_dentry->d_inode->i_mutex);
 679         return ret;
 680 }
 681
 682 const struct file_operations usbfs_devices_fops = {
 683         .llseek =       usb_device_lseek,
 684         .read =         usb_device_read,
 685         .poll =         usb_device_poll,
 686 };