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 /dev/bus/usb/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 /sys/kernel/debug/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  * Wait for an connect/disconnect event to happen. We initialize
 115  * the event counter with an odd number, and each event will increment
 116  * the event counter by two, so it will always _stay_ odd. That means
 117  * that it will never be zero, so "event 0" will never match a current
 118  * event, and thus 'poll' will always trigger as readable for the first
 119  * time it gets called.
 120  */
 121 static struct device_connect_event {
 122         atomic_t count;
 123         wait_queue_head_t wait;
 124 } device_event = {
 125         .count = ATOMIC_INIT(1),
 126         .wait = __WAIT_QUEUE_HEAD_INITIALIZER(device_event.wait)
 127 };
 128
 129 struct class_info {
 130         int class;
 131         char *class_name;
 132 };
 133
 134 static const struct class_info clas_info[] = {
 135         /* max. 5 chars. per name string */
 136         {USB_CLASS_PER_INTERFACE,       ">ifc"},
 137         {USB_CLASS_AUDIO,               "audio"},
 138         {USB_CLASS_COMM,                "comm."},
 139         {USB_CLASS_HID,                 "HID"},
 140         {USB_CLASS_PHYSICAL,            "PID"},
 141         {USB_CLASS_STILL_IMAGE,         "still"},
 142         {USB_CLASS_PRINTER,             "print"},
 143         {USB_CLASS_MASS_STORAGE,        "stor."},
 144         {USB_CLASS_HUB,                 "hub"},
 145         {USB_CLASS_CDC_DATA,            "data"},
 146         {USB_CLASS_CSCID,               "scard"},
 147         {USB_CLASS_CONTENT_SEC,         "c-sec"},
 148         {USB_CLASS_VIDEO,               "video"},
 149         {USB_CLASS_WIRELESS_CONTROLLER, "wlcon"},
 150         {USB_CLASS_MISC,                "misc"},
 151         {USB_CLASS_APP_SPEC,            "app."},
 152         {USB_CLASS_VENDOR_SPEC,         "vend."},
 153         {-1,                            "unk."}         /* leave as last */
 154 };
 155
 156 /*****************************************************************/
 157
 158 void usbfs_conn_disc_event(void)
 159 {
 160         atomic_add(2, &device_event.count);
 161         wake_up(&device_event.wait);
 162 }
 163
 164 static const char *class_decode(const int class)
 165 {
 166         int ix;
 167
 168         for (ix = 0; clas_info[ix].class != -1; ix++)
 169                 if (clas_info[ix].class == class)
 170                         break;
 171         return clas_info[ix].class_name;
 172 }
 173
 174 static char *usb_dump_endpoint_descriptor(int speed, char *start, char *end,
 175                                 const struct usb_endpoint_descriptor *desc)
 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                 bandwidth = usb_endpoint_maxp_mult(desc);
 187
 188         /* this isn't checking for illegal values */
 189         switch (usb_endpoint_type(desc)) {
 190         case USB_ENDPOINT_XFER_CONTROL:
 191                 type = "Ctrl";
 192                 if (speed == USB_SPEED_HIGH)    /* uframes per NAK */
 193                         interval = desc->bInterval;
 194                 else
 195                         interval = 0;
 196                 dir = 'B';                      /* ctrl is bidirectional */
 197                 break;
 198         case USB_ENDPOINT_XFER_ISOC:
 199                 type = "Isoc";
 200                 interval = 1 << (desc->bInterval - 1);
 201                 break;
 202         case USB_ENDPOINT_XFER_BULK:
 203                 type = "Bulk";
 204                 if (speed == USB_SPEED_HIGH && dir == 'O') /* uframes per NAK */
 205                         interval = desc->bInterval;
 206                 else
 207                         interval = 0;
 208                 break;
 209         case USB_ENDPOINT_XFER_INT:
 210                 type = "Int.";
 211                 if (speed == USB_SPEED_HIGH || speed >= USB_SPEED_SUPER)
 212                         interval = 1 << (desc->bInterval - 1);
 213                 else
 214                         interval = desc->bInterval;
 215                 break;
 216         default:        /* "can't happen" */
 217                 return start;
 218         }
 219         interval *= (speed == USB_SPEED_HIGH ||
 220                      speed >= USB_SPEED_SUPER) ? 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                          usb_endpoint_maxp(desc) *
 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, int speed)
 307 {
 308         int mul;
 309
 310         if (start > end)
 311                 return start;
 312         if (speed >= USB_SPEED_SUPER)
 313                 mul = 8;
 314         else
 315                 mul = 2;
 316         start += sprintf(start, format_config,
 317                          /* mark active/actual/current cfg. */
 318                          active ? '*' : ' ',
 319                          desc->bNumInterfaces,
 320                          desc->bConfigurationValue,
 321                          desc->bmAttributes,
 322                          desc->bMaxPower * mul);
 323         return start;
 324 }
 325
 326 static char *usb_dump_config(int speed, char *start, char *end,
 327                              const struct usb_host_config *config, int active)
 328 {
 329         int i, j;
 330         struct usb_interface_cache *intfc;
 331         struct usb_interface *interface;
 332
 333         if (start > end)
 334                 return start;
 335         if (!config)
 336                 /* getting these some in 2.3.7; none in 2.3.6 */
 337                 return start + sprintf(start, "(null Cfg. desc.)\n");
 338         start = usb_dump_config_descriptor(start, end, &config->desc, active,
 339                         speed);
 340         for (i = 0; i < USB_MAXIADS; i++) {
 341                 if (config->intf_assoc[i] == NULL)
 342                         break;
 343                 start = usb_dump_iad_descriptor(start, end,
 344                                         config->intf_assoc[i]);
 345         }
 346         for (i = 0; i < config->desc.bNumInterfaces; i++) {
 347                 intfc = config->intf_cache[i];
 348                 interface = config->interface[i];
 349                 for (j = 0; j < intfc->num_altsetting; j++) {
 350                         if (start > end)
 351                                 return start;
 352                         start = usb_dump_interface(speed,
 353                                 start, end, intfc, interface, j);
 354                 }
 355         }
 356         return start;
 357 }
 358
 359 /*
 360  * Dump the different USB descriptors.
 361  */
 362 static char *usb_dump_device_descriptor(char *start, char *end,
 363                                 const struct usb_device_descriptor *desc)
 364 {
 365         u16 bcdUSB = le16_to_cpu(desc->bcdUSB);
 366         u16 bcdDevice = le16_to_cpu(desc->bcdDevice);
 367
 368         if (start > end)
 369                 return start;
 370         start += sprintf(start, format_device1,
 371                           bcdUSB >> 8, bcdUSB & 0xff,
 372                           desc->bDeviceClass,
 373                           class_decode(desc->bDeviceClass),
 374                           desc->bDeviceSubClass,
 375                           desc->bDeviceProtocol,
 376                           desc->bMaxPacketSize0,
 377                           desc->bNumConfigurations);
 378         if (start > end)
 379                 return start;
 380         start += sprintf(start, format_device2,
 381                          le16_to_cpu(desc->idVendor),
 382                          le16_to_cpu(desc->idProduct),
 383                          bcdDevice >> 8, bcdDevice & 0xff);
 384         return start;
 385 }
 386
 387 /*
 388  * Dump the different strings that this device holds.
 389  */
 390 static char *usb_dump_device_strings(char *start, char *end,
 391                                      struct usb_device *dev)
 392 {
 393         if (start > end)
 394                 return start;
 395         if (dev->manufacturer)
 396                 start += sprintf(start, format_string_manufacturer,
 397                                  dev->manufacturer);
 398         if (start > end)
 399                 goto out;
 400         if (dev->product)
 401                 start += sprintf(start, format_string_product, dev->product);
 402         if (start > end)
 403                 goto out;
 404 #ifdef ALLOW_SERIAL_NUMBER
 405         if (dev->serial)
 406                 start += sprintf(start, format_string_serialnumber,
 407                                  dev->serial);
 408 #endif
 409  out:
 410         return start;
 411 }
 412
 413 static char *usb_dump_desc(char *start, char *end, struct usb_device *dev)
 414 {
 415         int i;
 416
 417         if (start > end)
 418                 return start;
 419
 420         start = usb_dump_device_descriptor(start, end, &dev->descriptor);
 421
 422         if (start > end)
 423                 return start;
 424
 425         start = usb_dump_device_strings(start, end, dev);
 426
 427         for (i = 0; i < dev->descriptor.bNumConfigurations; i++) {
 428                 if (start > end)
 429                         return start;
 430                 start = usb_dump_config(dev->speed,
 431                                 start, end, dev->config + i,
 432                                 /* active ? */
 433                                 (dev->config + i) == dev->actconfig);
 434         }
 435         return start;
 436 }
 437
 438
 439 #ifdef PROC_EXTRA /* TBD: may want to add this code later */
 440
 441 static char *usb_dump_hub_descriptor(char *start, char *end,
 442                                      const struct usb_hub_descriptor *desc)
 443 {
 444         int leng = USB_DT_HUB_NONVAR_SIZE;
 445         unsigned char *ptr = (unsigned char *)desc;
 446
 447         if (start > end)
 448                 return start;
 449         start += sprintf(start, "Interface:");
 450         while (leng && start <= end) {
 451                 start += sprintf(start, " %02x", *ptr);
 452                 ptr++; leng--;
 453         }
 454         *start++ = '\n';
 455         return start;
 456 }
 457
 458 static char *usb_dump_string(char *start, char *end,
 459                              const struct usb_device *dev, char *id, int index)
 460 {
 461         if (start > end)
 462                 return start;
 463         start += sprintf(start, "Interface:");
 464         if (index <= dev->maxstring && dev->stringindex &&
 465             dev->stringindex[index])
 466                 start += sprintf(start, "%s: %.100s ", id,
 467                                  dev->stringindex[index]);
 468         return start;
 469 }
 470
 471 #endif /* PROC_EXTRA */
 472
 473 /*****************************************************************/
 474
 475 /* This is a recursive function. Parameters:
 476  * buffer - the user-space buffer to write data into
 477  * nbytes - the maximum number of bytes to write
 478  * skip_bytes - the number of bytes to skip before writing anything
 479  * file_offset - the offset into the devices file on completion
 480  * The caller must own the device lock.
 481  */
 482 static ssize_t usb_device_dump(char __user **buffer, size_t *nbytes,
 483                                loff_t *skip_bytes, loff_t *file_offset,
 484                                struct usb_device *usbdev, struct usb_bus *bus,
 485                                int level, int index, int count)
 486 {
 487         int chix;
 488         int ret, cnt = 0;
 489         int parent_devnum = 0;
 490         char *pages_start, *data_end, *speed;
 491         unsigned int length;
 492         ssize_t total_written = 0;
 493         struct usb_device *childdev = NULL;
 494
 495         /* don't bother with anything else if we're not writing any data */
 496         if (*nbytes <= 0)
 497                 return 0;
 498
 499         if (level > MAX_TOPO_LEVEL)
 500                 return 0;
 501         /* allocate 2^1 pages = 8K (on i386);
 502          * should be more than enough for one device */
 503         pages_start = (char *)__get_free_pages(GFP_NOIO, 1);
 504         if (!pages_start)
 505                 return -ENOMEM;
 506
 507         if (usbdev->parent && usbdev->parent->devnum != -1)
 508                 parent_devnum = usbdev->parent->devnum;
 509         /*
 510          * So the root hub's parent is 0 and any device that is
 511          * plugged into the root hub has a parent of 0.
 512          */
 513         switch (usbdev->speed) {
 514         case USB_SPEED_LOW:
 515                 speed = "1.5"; break;
 516         case USB_SPEED_UNKNOWN:         /* usb 1.1 root hub code */
 517         case USB_SPEED_FULL:
 518                 speed = "12"; break;
 519         case USB_SPEED_WIRELESS:        /* Wireless has no real fixed speed */
 520         case USB_SPEED_HIGH:
 521                 speed = "480"; break;
 522         case USB_SPEED_SUPER:
 523                 speed = "5000"; break;
 524         case USB_SPEED_SUPER_PLUS:
 525                 speed = "10000"; break;
 526         default:
 527                 speed = "??";
 528         }
 529         data_end = pages_start + sprintf(pages_start, format_topo,
 530                         bus->busnum, level, parent_devnum,
 531                         index, count, usbdev->devnum,
 532                         speed, usbdev->maxchild);
 533         /*
 534          * level = topology-tier level;
 535          * parent_devnum = parent device number;
 536          * index = parent's connector number;
 537          * count = device count at this level
 538          */
 539         /* If this is the root hub, display the bandwidth information */
 540         if (level == 0) {
 541                 int     max;
 542
 543                 /* super/high speed reserves 80%, full/low reserves 90% */
 544                 if (usbdev->speed == USB_SPEED_HIGH ||
 545                     usbdev->speed >= USB_SPEED_SUPER)
 546                         max = 800;
 547                 else
 548                         max = FRAME_TIME_MAX_USECS_ALLOC;
 549
 550                 /* report "average" periodic allocation over a microsecond.
 551                  * the schedules are actually bursty, HCDs need to deal with
 552                  * that and just compute/report this average.
 553                  */
 554                 data_end += sprintf(data_end, format_bandwidth,
 555                                 bus->bandwidth_allocated, max,
 556                                 (100 * bus->bandwidth_allocated + max / 2)
 557                                         / max,
 558                                 bus->bandwidth_int_reqs,
 559                                 bus->bandwidth_isoc_reqs);
 560
 561         }
 562         data_end = usb_dump_desc(data_end, pages_start + (2 * PAGE_SIZE) - 256,
 563                                  usbdev);
 564
 565         if (data_end > (pages_start + (2 * PAGE_SIZE) - 256))
 566                 data_end += sprintf(data_end, "(truncated)\n");
 567
 568         length = data_end - pages_start;
 569         /* if we can start copying some data to the user */
 570         if (length > *skip_bytes) {
 571                 length -= *skip_bytes;
 572                 if (length > *nbytes)
 573                         length = *nbytes;
 574                 if (copy_to_user(*buffer, pages_start + *skip_bytes, length)) {
 575                         free_pages((unsigned long)pages_start, 1);
 576                         return -EFAULT;
 577                 }
 578                 *nbytes -= length;
 579                 *file_offset += length;
 580                 total_written += length;
 581                 *buffer += length;
 582                 *skip_bytes = 0;
 583         } else
 584                 *skip_bytes -= length;
 585
 586         free_pages((unsigned long)pages_start, 1);
 587
 588         /* Now look at all of this device's children. */
 589         usb_hub_for_each_child(usbdev, chix, childdev) {
 590                 usb_lock_device(childdev);
 591                 ret = usb_device_dump(buffer, nbytes, skip_bytes,
 592                                       file_offset, childdev, bus,
 593                                       level + 1, chix - 1, ++cnt);
 594                 usb_unlock_device(childdev);
 595                 if (ret == -EFAULT)
 596                         return total_written;
 597                 total_written += ret;
 598         }
 599         return total_written;
 600 }
 601
 602 static ssize_t usb_device_read(struct file *file, char __user *buf,
 603                                size_t nbytes, loff_t *ppos)
 604 {
 605         struct usb_bus *bus;
 606         ssize_t ret, total_written = 0;
 607         loff_t skip_bytes = *ppos;
 608         int id;
 609
 610         if (*ppos < 0)
 611                 return -EINVAL;
 612         if (nbytes <= 0)
 613                 return 0;
 614         if (!access_ok(VERIFY_WRITE, buf, nbytes))
 615                 return -EFAULT;
 616
 617         mutex_lock(&usb_bus_idr_lock);
 618         /* print devices for all busses */
 619         idr_for_each_entry(&usb_bus_idr, bus, id) {
 620                 /* recurse through all children of the root hub */
 621                 if (!bus_to_hcd(bus)->rh_registered)
 622                         continue;
 623                 usb_lock_device(bus->root_hub);
 624                 ret = usb_device_dump(&buf, &nbytes, &skip_bytes, ppos,
 625                                       bus->root_hub, bus, 0, 0, 0);
 626                 usb_unlock_device(bus->root_hub);
 627                 if (ret < 0) {
 628                         mutex_unlock(&usb_bus_idr_lock);
 629                         return ret;
 630                 }
 631                 total_written += ret;
 632         }
 633         mutex_unlock(&usb_bus_idr_lock);
 634         return total_written;
 635 }
 636
 637 /* Kernel lock for "lastev" protection */
 638 static unsigned int usb_device_poll(struct file *file,
 639                                     struct poll_table_struct *wait)
 640 {
 641         unsigned int event_count;
 642
 643         poll_wait(file, &device_event.wait, wait);
 644
 645         event_count = atomic_read(&device_event.count);
 646         if (file->f_version != event_count) {
 647                 file->f_version = event_count;
 648                 return POLLIN | POLLRDNORM;
 649         }
 650
 651         return 0;
 652 }
 653
 654 const struct file_operations usbfs_devices_fops = {
 655         .llseek =       no_seek_end_llseek,
 656         .read =         usb_device_read,
 657         .poll =         usb_device_poll,
 658 };