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 /*
 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 /* this struct stores the poll state for <mountpoint>/devices pollers */
 137 struct usb_device_status {
 138         unsigned int lastev;
 139 };
 140
 141 struct class_info {
 142         int class;
 143         char *class_name;
 144 };
 145
 146 static const struct class_info clas_info[] =
 147 {                                       /* max. 5 chars. per name string */
 148         {USB_CLASS_PER_INTERFACE,       ">ifc"},
 149         {USB_CLASS_AUDIO,               "audio"},
 150         {USB_CLASS_COMM,                "comm."},
 151         {USB_CLASS_HID,                 "HID"},
 152         {USB_CLASS_PHYSICAL,            "PID"},
 153         {USB_CLASS_STILL_IMAGE,         "still"},
 154         {USB_CLASS_PRINTER,             "print"},
 155         {USB_CLASS_MASS_STORAGE,        "stor."},
 156         {USB_CLASS_HUB,                 "hub"},
 157         {USB_CLASS_CDC_DATA,            "data"},
 158         {USB_CLASS_CSCID,               "scard"},
 159         {USB_CLASS_CONTENT_SEC,         "c-sec"},
 160         {USB_CLASS_VIDEO,               "video"},
 161         {USB_CLASS_WIRELESS_CONTROLLER, "wlcon"},
 162         {USB_CLASS_MISC,                "misc"},
 163         {USB_CLASS_APP_SPEC,            "app."},
 164         {USB_CLASS_VENDOR_SPEC,         "vend."},
 165         {-1,                            "unk."}         /* leave as last */
 166 };
 167
 168 /*****************************************************************/
 169
 170 void usbfs_conn_disc_event(void)
 171 {
 172         atomic_add(2, &device_event.count);
 173         wake_up(&device_event.wait);
 174 }
 175
 176 static const char *class_decode(const int class)
 177 {
 178         int ix;
 179
 180         for (ix = 0; clas_info[ix].class != -1; ix++)
 181                 if (clas_info[ix].class == class)
 182                         break;
 183         return clas_info[ix].class_name;
 184 }
 185
 186 static char *usb_dump_endpoint_descriptor(int speed, char *start, char *end,
 187                                 const struct usb_endpoint_descriptor *desc)
 188 {
 189         char dir, unit, *type;
 190         unsigned interval, bandwidth = 1;
 191
 192         if (start > end)
 193                 return start;
 194
 195         dir = usb_endpoint_dir_in(desc) ? 'I' : 'O';
 196
 197         if (speed == USB_SPEED_HIGH) {
 198                 switch (le16_to_cpu(desc->wMaxPacketSize) & (0x03 << 11)) {
 199                 case 1 << 11:   bandwidth = 2; break;
 200                 case 2 << 11:   bandwidth = 3; break;
 201                 }
 202         }
 203
 204         /* this isn't checking for illegal values */
 205         switch (usb_endpoint_type(desc)) {
 206         case USB_ENDPOINT_XFER_CONTROL:
 207                 type = "Ctrl";
 208                 if (speed == USB_SPEED_HIGH)    /* uframes per NAK */
 209                         interval = desc->bInterval;
 210                 else
 211                         interval = 0;
 212                 dir = 'B';                      /* ctrl is bidirectional */
 213                 break;
 214         case USB_ENDPOINT_XFER_ISOC:
 215                 type = "Isoc";
 216                 interval = 1 << (desc->bInterval - 1);
 217                 break;
 218         case USB_ENDPOINT_XFER_BULK:
 219                 type = "Bulk";
 220                 if (speed == USB_SPEED_HIGH && dir == 'O') /* uframes per NAK */
 221                         interval = desc->bInterval;
 222                 else
 223                         interval = 0;
 224                 break;
 225         case USB_ENDPOINT_XFER_INT:
 226                 type = "Int.";
 227                 if (speed == USB_SPEED_HIGH)
 228                         interval = 1 << (desc->bInterval - 1);
 229                 else
 230                         interval = desc->bInterval;
 231                 break;
 232         default:        /* "can't happen" */
 233                 return start;
 234         }
 235         interval *= (speed == USB_SPEED_HIGH) ? 125 : 1000;
 236         if (interval % 1000)
 237                 unit = 'u';
 238         else {
 239                 unit = 'm';
 240                 interval /= 1000;
 241         }
 242
 243         start += sprintf(start, format_endpt, desc->bEndpointAddress, dir,
 244                          desc->bmAttributes, type,
 245                          (le16_to_cpu(desc->wMaxPacketSize) & 0x07ff) *
 246                          bandwidth,
 247                          interval, unit);
 248         return start;
 249 }
 250
 251 static char *usb_dump_interface_descriptor(char *start, char *end,
 252                                         const struct usb_interface_cache *intfc,
 253                                         const struct usb_interface *iface,
 254                                         int setno)
 255 {
 256         const struct usb_interface_descriptor *desc;
 257         const char *driver_name = "";
 258         int active = 0;
 259
 260         if (start > end)
 261                 return start;
 262         desc = &intfc->altsetting[setno].desc;
 263         if (iface) {
 264                 driver_name = (iface->dev.driver
 265                                 ? iface->dev.driver->name
 266                                 : "(none)");
 267                 active = (desc == &iface->cur_altsetting->desc);
 268         }
 269         start += sprintf(start, format_iface,
 270                          active ? '*' : ' ',    /* mark active altsetting */
 271                          desc->bInterfaceNumber,
 272                          desc->bAlternateSetting,
 273                          desc->bNumEndpoints,
 274                          desc->bInterfaceClass,
 275                          class_decode(desc->bInterfaceClass),
 276                          desc->bInterfaceSubClass,
 277                          desc->bInterfaceProtocol,
 278                          driver_name);
 279         return start;
 280 }
 281
 282 static char *usb_dump_interface(int speed, char *start, char *end,
 283                                 const struct usb_interface_cache *intfc,
 284                                 const struct usb_interface *iface, int setno)
 285 {
 286         const struct usb_host_interface *desc = &intfc->altsetting[setno];
 287         int i;
 288
 289         start = usb_dump_interface_descriptor(start, end, intfc, iface, setno);
 290         for (i = 0; i < desc->desc.bNumEndpoints; i++) {
 291                 if (start > end)
 292                         return start;
 293                 start = usb_dump_endpoint_descriptor(speed,
 294                                 start, end, &desc->endpoint[i].desc);
 295         }
 296         return start;
 297 }
 298
 299 static char *usb_dump_iad_descriptor(char *start, char *end,
 300                         const struct usb_interface_assoc_descriptor *iad)
 301 {
 302         if (start > end)
 303                 return start;
 304         start += sprintf(start, format_iad,
 305                          iad->bFirstInterface,
 306                          iad->bInterfaceCount,
 307                          iad->bFunctionClass,
 308                          class_decode(iad->bFunctionClass),
 309                          iad->bFunctionSubClass,
 310                          iad->bFunctionProtocol);
 311         return start;
 312 }
 313
 314 /* TBD:
 315  * 0. TBDs
 316  * 1. marking active interface altsettings (code lists all, but should mark
 317  *    which ones are active, if any)
 318  */
 319 static char *usb_dump_config_descriptor(char *start, char *end,
 320                                 const struct usb_config_descriptor *desc,
 321                                 int active)
 322 {
 323         if (start > end)
 324                 return start;
 325         start += sprintf(start, format_config,
 326                          /* mark active/actual/current cfg. */
 327                          active ? '*' : ' ',
 328                          desc->bNumInterfaces,
 329                          desc->bConfigurationValue,
 330                          desc->bmAttributes,
 331                          desc->bMaxPower * 2);
 332         return start;
 333 }
 334
 335 static char *usb_dump_config(int speed, char *start, char *end,
 336                              const struct usb_host_config *config, int active)
 337 {
 338         int i, j;
 339         struct usb_interface_cache *intfc;
 340         struct usb_interface *interface;
 341
 342         if (start > end)
 343                 return start;
 344         if (!config)
 345                 /* getting these some in 2.3.7; none in 2.3.6 */
 346                 return start + sprintf(start, "(null Cfg. desc.)\n");
 347         start = usb_dump_config_descriptor(start, end, &config->desc, active);
 348         for (i = 0; i < USB_MAXIADS; i++) {
 349                 if (config->intf_assoc[i] == NULL)
 350                         break;
 351                 start = usb_dump_iad_descriptor(start, end,
 352                                         config->intf_assoc[i]);
 353         }
 354         for (i = 0; i < config->desc.bNumInterfaces; i++) {
 355                 intfc = config->intf_cache[i];
 356                 interface = config->interface[i];
 357                 for (j = 0; j < intfc->num_altsetting; j++) {
 358                         if (start > end)
 359                                 return start;
 360                         start = usb_dump_interface(speed,
 361                                 start, end, intfc, interface, j);
 362                 }
 363         }
 364         return start;
 365 }
 366
 367 /*
 368  * Dump the different USB descriptors.
 369  */
 370 static char *usb_dump_device_descriptor(char *start, char *end,
 371                                 const struct usb_device_descriptor *desc)
 372 {
 373         u16 bcdUSB = le16_to_cpu(desc->bcdUSB);
 374         u16 bcdDevice = le16_to_cpu(desc->bcdDevice);
 375
 376         if (start > end)
 377                 return start;
 378         start += sprintf(start, format_device1,
 379                           bcdUSB >> 8, bcdUSB & 0xff,
 380                           desc->bDeviceClass,
 381                           class_decode(desc->bDeviceClass),
 382                           desc->bDeviceSubClass,
 383                           desc->bDeviceProtocol,
 384                           desc->bMaxPacketSize0,
 385                           desc->bNumConfigurations);
 386         if (start > end)
 387                 return start;
 388         start += sprintf(start, format_device2,
 389                          le16_to_cpu(desc->idVendor),
 390                          le16_to_cpu(desc->idProduct),
 391                          bcdDevice >> 8, bcdDevice & 0xff);
 392         return start;
 393 }
 394
 395 /*
 396  * Dump the different strings that this device holds.
 397  */
 398 static char *usb_dump_device_strings(char *start, char *end,
 399                                      struct usb_device *dev)
 400 {
 401         if (start > end)
 402                 return start;
 403         if (dev->manufacturer)
 404                 start += sprintf(start, format_string_manufacturer,
 405                                  dev->manufacturer);
 406         if (start > end)
 407                 goto out;
 408         if (dev->product)
 409                 start += sprintf(start, format_string_product, dev->product);
 410         if (start > end)
 411                 goto out;
 412 #ifdef ALLOW_SERIAL_NUMBER
 413         if (dev->serial)
 414                 start += sprintf(start, format_string_serialnumber,
 415                                  dev->serial);
 416 #endif
 417  out:
 418         return start;
 419 }
 420
 421 static char *usb_dump_desc(char *start, char *end, struct usb_device *dev)
 422 {
 423         int i;
 424
 425         if (start > end)
 426                 return start;
 427
 428         start = usb_dump_device_descriptor(start, end, &dev->descriptor);
 429
 430         if (start > end)
 431                 return start;
 432
 433         start = usb_dump_device_strings(start, end, dev);
 434
 435         for (i = 0; i < dev->descriptor.bNumConfigurations; i++) {
 436                 if (start > end)
 437                         return start;
 438                 start = usb_dump_config(dev->speed,
 439                                 start, end, dev->config + i,
 440                                 /* active ? */
 441                                 (dev->config + i) == dev->actconfig);
 442         }
 443         return start;
 444 }
 445
 446
 447 #ifdef PROC_EXTRA /* TBD: may want to add this code later */
 448
 449 static char *usb_dump_hub_descriptor(char *start, char *end,
 450                                      const struct usb_hub_descriptor *desc)
 451 {
 452         int leng = USB_DT_HUB_NONVAR_SIZE;
 453         unsigned char *ptr = (unsigned char *)desc;
 454
 455         if (start > end)
 456                 return start;
 457         start += sprintf(start, "Interface:");
 458         while (leng && start <= end) {
 459                 start += sprintf(start, " %02x", *ptr);
 460                 ptr++; leng--;
 461         }
 462         *start++ = '\n';
 463         return start;
 464 }
 465
 466 static char *usb_dump_string(char *start, char *end,
 467                              const struct usb_device *dev, char *id, int index)
 468 {
 469         if (start > end)
 470                 return start;
 471         start += sprintf(start, "Interface:");
 472         if (index <= dev->maxstring && dev->stringindex &&
 473             dev->stringindex[index])
 474                 start += sprintf(start, "%s: %.100s ", id,
 475                                  dev->stringindex[index]);
 476         return start;
 477 }
 478
 479 #endif /* PROC_EXTRA */
 480
 481 /*****************************************************************/
 482
 483 /* This is a recursive function. Parameters:
 484  * buffer - the user-space buffer to write data into
 485  * nbytes - the maximum number of bytes to write
 486  * skip_bytes - the number of bytes to skip before writing anything
 487  * file_offset - the offset into the devices file on completion
 488  * The caller must own the device lock.
 489  */
 490 static ssize_t usb_device_dump(char __user **buffer, size_t *nbytes,
 491                                loff_t *skip_bytes, loff_t *file_offset,
 492                                struct usb_device *usbdev, struct usb_bus *bus,
 493                                int level, int index, int count)
 494 {
 495         int chix;
 496         int ret, cnt = 0;
 497         int parent_devnum = 0;
 498         char *pages_start, *data_end, *speed;
 499         unsigned int length;
 500         ssize_t total_written = 0;
 501
 502         /* don't bother with anything else if we're not writing any data */
 503         if (*nbytes <= 0)
 504                 return 0;
 505
 506         if (level > MAX_TOPO_LEVEL)
 507                 return 0;
 508         /* allocate 2^1 pages = 8K (on i386);
 509          * should be more than enough for one device */
 510         pages_start = (char *)__get_free_pages(GFP_NOIO, 1);
 511         if (!pages_start)
 512                 return -ENOMEM;
 513
 514         if (usbdev->parent && usbdev->parent->devnum != -1)
 515                 parent_devnum = usbdev->parent->devnum;
 516         /*
 517          * So the root hub's parent is 0 and any device that is
 518          * plugged into the root hub has a parent of 0.
 519          */
 520         switch (usbdev->speed) {
 521         case USB_SPEED_LOW:
 522                 speed = "1.5"; break;
 523         case USB_SPEED_UNKNOWN:         /* usb 1.1 root hub code */
 524         case USB_SPEED_FULL:
 525                 speed = "12 "; break;
 526         case USB_SPEED_HIGH:
 527                 speed = "480"; 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 };