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  * 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                 switch (usb_endpoint_maxp(desc) & (0x03 << 11)) {
 187                 case 1 << 11:
 188                         bandwidth = 2; break;
 189                 case 2 << 11:
 190                         bandwidth = 3; break;
 191                 }
 192         }
 193
 194         /* this isn't checking for illegal values */
 195         switch (usb_endpoint_type(desc)) {
 196         case USB_ENDPOINT_XFER_CONTROL:
 197                 type = "Ctrl";
 198                 if (speed == USB_SPEED_HIGH)    /* uframes per NAK */
 199                         interval = desc->bInterval;
 200                 else
 201                         interval = 0;
 202                 dir = 'B';                      /* ctrl is bidirectional */
 203                 break;
 204         case USB_ENDPOINT_XFER_ISOC:
 205                 type = "Isoc";
 206                 interval = 1 << (desc->bInterval - 1);
 207                 break;
 208         case USB_ENDPOINT_XFER_BULK:
 209                 type = "Bulk";
 210                 if (speed == USB_SPEED_HIGH && dir == 'O') /* uframes per NAK */
 211                         interval = desc->bInterval;
 212                 else
 213                         interval = 0;
 214                 break;
 215         case USB_ENDPOINT_XFER_INT:
 216                 type = "Int.";
 217                 if (speed == USB_SPEED_HIGH || speed >= USB_SPEED_SUPER)
 218                         interval = 1 << (desc->bInterval - 1);
 219                 else
 220                         interval = desc->bInterval;
 221                 break;
 222         default:        /* "can't happen" */
 223                 return start;
 224         }
 225         interval *= (speed == USB_SPEED_HIGH ||
 226                      speed >= USB_SPEED_SUPER) ? 125 : 1000;
 227         if (interval % 1000)
 228                 unit = 'u';
 229         else {
 230                 unit = 'm';
 231                 interval /= 1000;
 232         }
 233
 234         start += sprintf(start, format_endpt, desc->bEndpointAddress, dir,
 235                          desc->bmAttributes, type,
 236                          (usb_endpoint_maxp(desc) & 0x07ff) *
 237                          bandwidth,
 238                          interval, unit);
 239         return start;
 240 }
 241
 242 static char *usb_dump_interface_descriptor(char *start, char *end,
 243                                         const struct usb_interface_cache *intfc,
 244                                         const struct usb_interface *iface,
 245                                         int setno)
 246 {
 247         const struct usb_interface_descriptor *desc;
 248         const char *driver_name = "";
 249         int active = 0;
 250
 251         if (start > end)
 252                 return start;
 253         desc = &intfc->altsetting[setno].desc;
 254         if (iface) {
 255                 driver_name = (iface->dev.driver
 256                                 ? iface->dev.driver->name
 257                                 : "(none)");
 258                 active = (desc == &iface->cur_altsetting->desc);
 259         }
 260         start += sprintf(start, format_iface,
 261                          active ? '*' : ' ',    /* mark active altsetting */
 262                          desc->bInterfaceNumber,
 263                          desc->bAlternateSetting,
 264                          desc->bNumEndpoints,
 265                          desc->bInterfaceClass,
 266                          class_decode(desc->bInterfaceClass),
 267                          desc->bInterfaceSubClass,
 268                          desc->bInterfaceProtocol,
 269                          driver_name);
 270         return start;
 271 }
 272
 273 static char *usb_dump_interface(int speed, char *start, char *end,
 274                                 const struct usb_interface_cache *intfc,
 275                                 const struct usb_interface *iface, int setno)
 276 {
 277         const struct usb_host_interface *desc = &intfc->altsetting[setno];
 278         int i;
 279
 280         start = usb_dump_interface_descriptor(start, end, intfc, iface, setno);
 281         for (i = 0; i < desc->desc.bNumEndpoints; i++) {
 282                 if (start > end)
 283                         return start;
 284                 start = usb_dump_endpoint_descriptor(speed,
 285                                 start, end, &desc->endpoint[i].desc);
 286         }
 287         return start;
 288 }
 289
 290 static char *usb_dump_iad_descriptor(char *start, char *end,
 291                         const struct usb_interface_assoc_descriptor *iad)
 292 {
 293         if (start > end)
 294                 return start;
 295         start += sprintf(start, format_iad,
 296                          iad->bFirstInterface,
 297                          iad->bInterfaceCount,
 298                          iad->bFunctionClass,
 299                          class_decode(iad->bFunctionClass),
 300                          iad->bFunctionSubClass,
 301                          iad->bFunctionProtocol);
 302         return start;
 303 }
 304
 305 /* TBD:
 306  * 0. TBDs
 307  * 1. marking active interface altsettings (code lists all, but should mark
 308  *    which ones are active, if any)
 309  */
 310 static char *usb_dump_config_descriptor(char *start, char *end,
 311                                 const struct usb_config_descriptor *desc,
 312                                 int active, int speed)
 313 {
 314         int mul;
 315
 316         if (start > end)
 317                 return start;
 318         if (speed >= USB_SPEED_SUPER)
 319                 mul = 8;
 320         else
 321                 mul = 2;
 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 * mul);
 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                         speed);
 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         struct usb_device *childdev = NULL;
 500
 501         /* don't bother with anything else if we're not writing any data */
 502         if (*nbytes <= 0)
 503                 return 0;
 504
 505         if (level > MAX_TOPO_LEVEL)
 506                 return 0;
 507         /* allocate 2^1 pages = 8K (on i386);
 508          * should be more than enough for one device */
 509         pages_start = (char *)__get_free_pages(GFP_NOIO, 1);
 510         if (!pages_start)
 511                 return -ENOMEM;
 512
 513         if (usbdev->parent && usbdev->parent->devnum != -1)
 514                 parent_devnum = usbdev->parent->devnum;
 515         /*
 516          * So the root hub's parent is 0 and any device that is
 517          * plugged into the root hub has a parent of 0.
 518          */
 519         switch (usbdev->speed) {
 520         case USB_SPEED_LOW:
 521                 speed = "1.5"; break;
 522         case USB_SPEED_UNKNOWN:         /* usb 1.1 root hub code */
 523         case USB_SPEED_FULL:
 524                 speed = "12"; break;
 525         case USB_SPEED_WIRELESS:        /* Wireless has no real fixed speed */
 526         case USB_SPEED_HIGH:
 527                 speed = "480"; break;
 528         case USB_SPEED_SUPER:
 529                 speed = "5000"; break;
 530         case USB_SPEED_SUPER_PLUS:
 531                 speed = "10000"; break;
 532         default:
 533                 speed = "??";
 534         }
 535         data_end = pages_start + sprintf(pages_start, format_topo,
 536                         bus->busnum, level, parent_devnum,
 537                         index, count, usbdev->devnum,
 538                         speed, usbdev->maxchild);
 539         /*
 540          * level = topology-tier level;
 541          * parent_devnum = parent device number;
 542          * index = parent's connector number;
 543          * count = device count at this level
 544          */
 545         /* If this is the root hub, display the bandwidth information */
 546         if (level == 0) {
 547                 int     max;
 548
 549                 /* super/high speed reserves 80%, full/low reserves 90% */
 550                 if (usbdev->speed == USB_SPEED_HIGH ||
 551                     usbdev->speed >= USB_SPEED_SUPER)
 552                         max = 800;
 553                 else
 554                         max = FRAME_TIME_MAX_USECS_ALLOC;
 555
 556                 /* report "average" periodic allocation over a microsecond.
 557                  * the schedules are actually bursty, HCDs need to deal with
 558                  * that and just compute/report this average.
 559                  */
 560                 data_end += sprintf(data_end, format_bandwidth,
 561                                 bus->bandwidth_allocated, max,
 562                                 (100 * bus->bandwidth_allocated + max / 2)
 563                                         / max,
 564                                 bus->bandwidth_int_reqs,
 565                                 bus->bandwidth_isoc_reqs);
 566
 567         }
 568         data_end = usb_dump_desc(data_end, pages_start + (2 * PAGE_SIZE) - 256,
 569                                  usbdev);
 570
 571         if (data_end > (pages_start + (2 * PAGE_SIZE) - 256))
 572                 data_end += sprintf(data_end, "(truncated)\n");
 573
 574         length = data_end - pages_start;
 575         /* if we can start copying some data to the user */
 576         if (length > *skip_bytes) {
 577                 length -= *skip_bytes;
 578                 if (length > *nbytes)
 579                         length = *nbytes;
 580                 if (copy_to_user(*buffer, pages_start + *skip_bytes, length)) {
 581                         free_pages((unsigned long)pages_start, 1);
 582                         return -EFAULT;
 583                 }
 584                 *nbytes -= length;
 585                 *file_offset += length;
 586                 total_written += length;
 587                 *buffer += length;
 588                 *skip_bytes = 0;
 589         } else
 590                 *skip_bytes -= length;
 591
 592         free_pages((unsigned long)pages_start, 1);
 593
 594         /* Now look at all of this device's children. */
 595         usb_hub_for_each_child(usbdev, chix, childdev) {
 596                 usb_lock_device(childdev);
 597                 ret = usb_device_dump(buffer, nbytes, skip_bytes,
 598                                       file_offset, childdev, bus,
 599                                       level + 1, chix - 1, ++cnt);
 600                 usb_unlock_device(childdev);
 601                 if (ret == -EFAULT)
 602                         return total_written;
 603                 total_written += ret;
 604         }
 605         return total_written;
 606 }
 607
 608 static ssize_t usb_device_read(struct file *file, char __user *buf,
 609                                size_t nbytes, loff_t *ppos)
 610 {
 611         struct usb_bus *bus;
 612         ssize_t ret, total_written = 0;
 613         loff_t skip_bytes = *ppos;
 614         int id;
 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_idr_lock);
 624         /* print devices for all busses */
 625         idr_for_each_entry(&usb_bus_idr, bus, id) {
 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_idr_lock);
 635                         return ret;
 636                 }
 637                 total_written += ret;
 638         }
 639         mutex_unlock(&usb_bus_idr_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 const struct file_operations usbfs_devices_fops = {
 661         .llseek =       no_seek_end_llseek,
 662         .read =         usb_device_read,
 663         .poll =         usb_device_poll,
 664 };