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   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 static DECLARE_WAIT_QUEUE_HEAD(deviceconndiscwq);
 121 static unsigned int conndiscevcnt;
 122
 123 /* this struct stores the poll state for <mountpoint>/devices pollers */
 124 struct usb_device_status {
 125         unsigned int lastev;
 126 };
 127
 128 struct class_info {
 129         int class;
 130         char *class_name;
 131 };
 132
 133 static const struct class_info clas_info[] =
 134 {                                       /* max. 5 chars. per name string */
 135         {USB_CLASS_PER_INTERFACE,       ">ifc"},
 136         {USB_CLASS_AUDIO,               "audio"},
 137         {USB_CLASS_COMM,                "comm."},
 138         {USB_CLASS_HID,                 "HID"},
 139         {USB_CLASS_PHYSICAL,            "PID"},
 140         {USB_CLASS_STILL_IMAGE,         "still"},
 141         {USB_CLASS_PRINTER,             "print"},
 142         {USB_CLASS_MASS_STORAGE,        "stor."},
 143         {USB_CLASS_HUB,                 "hub"},
 144         {USB_CLASS_CDC_DATA,            "data"},
 145         {USB_CLASS_CSCID,               "scard"},
 146         {USB_CLASS_CONTENT_SEC,         "c-sec"},
 147         {USB_CLASS_VIDEO,               "video"},
 148         {USB_CLASS_WIRELESS_CONTROLLER, "wlcon"},
 149         {USB_CLASS_MISC,                "misc"},
 150         {USB_CLASS_APP_SPEC,            "app."},
 151         {USB_CLASS_VENDOR_SPEC,         "vend."},
 152         {-1,                            "unk."}         /* leave as last */
 153 };
 154
 155 /*****************************************************************/
 156
 157 void usbfs_conn_disc_event(void)
 158 {
 159         conndiscevcnt++;
 160         wake_up(&deviceconndiscwq);
 161 }
 162
 163 static const char *class_decode(const int class)
 164 {
 165         int ix;
 166
 167         for (ix = 0; clas_info[ix].class != -1; ix++)
 168                 if (clas_info[ix].class == class)
 169                         break;
 170         return clas_info[ix].class_name;
 171 }
 172
 173 static char *usb_dump_endpoint_descriptor(int speed, char *start, char *end,
 174                                 const struct usb_endpoint_descriptor *desc)
 175 {
 176         char dir, unit, *type;
 177         unsigned interval, bandwidth = 1;
 178
 179         if (start > end)
 180                 return start;
 181
 182         dir = usb_endpoint_dir_in(desc) ? 'I' : 'O';
 183
 184         if (speed == USB_SPEED_HIGH) {
 185                 switch (le16_to_cpu(desc->wMaxPacketSize) & (0x03 << 11)) {
 186                 case 1 << 11:   bandwidth = 2; break;
 187                 case 2 << 11:   bandwidth = 3; break;
 188                 }
 189         }
 190
 191         /* this isn't checking for illegal values */
 192         switch (usb_endpoint_type(desc)) {
 193         case USB_ENDPOINT_XFER_CONTROL:
 194                 type = "Ctrl";
 195                 if (speed == USB_SPEED_HIGH)    /* uframes per NAK */
 196                         interval = desc->bInterval;
 197                 else
 198                         interval = 0;
 199                 dir = 'B';                      /* ctrl is bidirectional */
 200                 break;
 201         case USB_ENDPOINT_XFER_ISOC:
 202                 type = "Isoc";
 203                 interval = 1 << (desc->bInterval - 1);
 204                 break;
 205         case USB_ENDPOINT_XFER_BULK:
 206                 type = "Bulk";
 207                 if (speed == USB_SPEED_HIGH && dir == 'O') /* uframes per NAK */
 208                         interval = desc->bInterval;
 209                 else
 210                         interval = 0;
 211                 break;
 212         case USB_ENDPOINT_XFER_INT:
 213                 type = "Int.";
 214                 if (speed == USB_SPEED_HIGH)
 215                         interval = 1 << (desc->bInterval - 1);
 216                 else
 217                         interval = desc->bInterval;
 218                 break;
 219         default:        /* "can't happen" */
 220                 return start;
 221         }
 222         interval *= (speed == USB_SPEED_HIGH) ? 125 : 1000;
 223         if (interval % 1000)
 224                 unit = 'u';
 225         else {
 226                 unit = 'm';
 227                 interval /= 1000;
 228         }
 229
 230         start += sprintf(start, format_endpt, desc->bEndpointAddress, dir,
 231                          desc->bmAttributes, type,
 232                          (le16_to_cpu(desc->wMaxPacketSize) & 0x07ff) *
 233                          bandwidth,
 234                          interval, unit);
 235         return start;
 236 }
 237
 238 static char *usb_dump_interface_descriptor(char *start, char *end,
 239                                         const struct usb_interface_cache *intfc,
 240                                         const struct usb_interface *iface,
 241                                         int setno)
 242 {
 243         const struct usb_interface_descriptor *desc;
 244         const char *driver_name = "";
 245         int active = 0;
 246
 247         if (start > end)
 248                 return start;
 249         desc = &intfc->altsetting[setno].desc;
 250         if (iface) {
 251                 driver_name = (iface->dev.driver
 252                                 ? iface->dev.driver->name
 253                                 : "(none)");
 254                 active = (desc == &iface->cur_altsetting->desc);
 255         }
 256         start += sprintf(start, format_iface,
 257                          active ? '*' : ' ',    /* mark active altsetting */
 258                          desc->bInterfaceNumber,
 259                          desc->bAlternateSetting,
 260                          desc->bNumEndpoints,
 261                          desc->bInterfaceClass,
 262                          class_decode(desc->bInterfaceClass),
 263                          desc->bInterfaceSubClass,
 264                          desc->bInterfaceProtocol,
 265                          driver_name);
 266         return start;
 267 }
 268
 269 static char *usb_dump_interface(int speed, char *start, char *end,
 270                                 const struct usb_interface_cache *intfc,
 271                                 const struct usb_interface *iface, int setno)
 272 {
 273         const struct usb_host_interface *desc = &intfc->altsetting[setno];
 274         int i;
 275
 276         start = usb_dump_interface_descriptor(start, end, intfc, iface, setno);
 277         for (i = 0; i < desc->desc.bNumEndpoints; i++) {
 278                 if (start > end)
 279                         return start;
 280                 start = usb_dump_endpoint_descriptor(speed,
 281                                 start, end, &desc->endpoint[i].desc);
 282         }
 283         return start;
 284 }
 285
 286 static char *usb_dump_iad_descriptor(char *start, char *end,
 287                         const struct usb_interface_assoc_descriptor *iad)
 288 {
 289         if (start > end)
 290                 return start;
 291         start += sprintf(start, format_iad,
 292                          iad->bFirstInterface,
 293                          iad->bInterfaceCount,
 294                          iad->bFunctionClass,
 295                          class_decode(iad->bFunctionClass),
 296                          iad->bFunctionSubClass,
 297                          iad->bFunctionProtocol);
 298         return start;
 299 }
 300
 301 /* TBD:
 302  * 0. TBDs
 303  * 1. marking active interface altsettings (code lists all, but should mark
 304  *    which ones are active, if any)
 305  */
 306 static char *usb_dump_config_descriptor(char *start, char *end,
 307                                 const struct usb_config_descriptor *desc,
 308                                 int active)
 309 {
 310         if (start > end)
 311                 return start;
 312         start += sprintf(start, format_config,
 313                          /* mark active/actual/current cfg. */
 314                          active ? '*' : ' ',
 315                          desc->bNumInterfaces,
 316                          desc->bConfigurationValue,
 317                          desc->bmAttributes,
 318                          desc->bMaxPower * 2);
 319         return start;
 320 }
 321
 322 static char *usb_dump_config(int speed, char *start, char *end,
 323                              const struct usb_host_config *config, int active)
 324 {
 325         int i, j;
 326         struct usb_interface_cache *intfc;
 327         struct usb_interface *interface;
 328
 329         if (start > end)
 330                 return start;
 331         if (!config)
 332                 /* getting these some in 2.3.7; none in 2.3.6 */
 333                 return start + sprintf(start, "(null Cfg. desc.)\n");
 334         start = usb_dump_config_descriptor(start, end, &config->desc, active);
 335         for (i = 0; i < USB_MAXIADS; i++) {
 336                 if (config->intf_assoc[i] == NULL)
 337                         break;
 338                 start = usb_dump_iad_descriptor(start, end,
 339                                         config->intf_assoc[i]);
 340         }
 341         for (i = 0; i < config->desc.bNumInterfaces; i++) {
 342                 intfc = config->intf_cache[i];
 343                 interface = config->interface[i];
 344                 for (j = 0; j < intfc->num_altsetting; j++) {
 345                         if (start > end)
 346                                 return start;
 347                         start = usb_dump_interface(speed,
 348                                 start, end, intfc, interface, j);
 349                 }
 350         }
 351         return start;
 352 }
 353
 354 /*
 355  * Dump the different USB descriptors.
 356  */
 357 static char *usb_dump_device_descriptor(char *start, char *end,
 358                                 const struct usb_device_descriptor *desc)
 359 {
 360         u16 bcdUSB = le16_to_cpu(desc->bcdUSB);
 361         u16 bcdDevice = le16_to_cpu(desc->bcdDevice);
 362
 363         if (start > end)
 364                 return start;
 365         start += sprintf(start, format_device1,
 366                           bcdUSB >> 8, bcdUSB & 0xff,
 367                           desc->bDeviceClass,
 368                           class_decode(desc->bDeviceClass),
 369                           desc->bDeviceSubClass,
 370                           desc->bDeviceProtocol,
 371                           desc->bMaxPacketSize0,
 372                           desc->bNumConfigurations);
 373         if (start > end)
 374                 return start;
 375         start += sprintf(start, format_device2,
 376                          le16_to_cpu(desc->idVendor),
 377                          le16_to_cpu(desc->idProduct),
 378                          bcdDevice >> 8, bcdDevice & 0xff);
 379         return start;
 380 }
 381
 382 /*
 383  * Dump the different strings that this device holds.
 384  */
 385 static char *usb_dump_device_strings(char *start, char *end,
 386                                      struct usb_device *dev)
 387 {
 388         if (start > end)
 389                 return start;
 390         if (dev->manufacturer)
 391                 start += sprintf(start, format_string_manufacturer,
 392                                  dev->manufacturer);
 393         if (start > end)
 394                 goto out;
 395         if (dev->product)
 396                 start += sprintf(start, format_string_product, dev->product);
 397         if (start > end)
 398                 goto out;
 399 #ifdef ALLOW_SERIAL_NUMBER
 400         if (dev->serial)
 401                 start += sprintf(start, format_string_serialnumber,
 402                                  dev->serial);
 403 #endif
 404  out:
 405         return start;
 406 }
 407
 408 static char *usb_dump_desc(char *start, char *end, struct usb_device *dev)
 409 {
 410         int i;
 411
 412         if (start > end)
 413                 return start;
 414
 415         start = usb_dump_device_descriptor(start, end, &dev->descriptor);
 416
 417         if (start > end)
 418                 return start;
 419
 420         start = usb_dump_device_strings(start, end, dev);
 421
 422         for (i = 0; i < dev->descriptor.bNumConfigurations; i++) {
 423                 if (start > end)
 424                         return start;
 425                 start = usb_dump_config(dev->speed,
 426                                 start, end, dev->config + i,
 427                                 /* active ? */
 428                                 (dev->config + i) == dev->actconfig);
 429         }
 430         return start;
 431 }
 432
 433
 434 #ifdef PROC_EXTRA /* TBD: may want to add this code later */
 435
 436 static char *usb_dump_hub_descriptor(char *start, char *end,
 437                                      const struct usb_hub_descriptor *desc)
 438 {
 439         int leng = USB_DT_HUB_NONVAR_SIZE;
 440         unsigned char *ptr = (unsigned char *)desc;
 441
 442         if (start > end)
 443                 return start;
 444         start += sprintf(start, "Interface:");
 445         while (leng && start <= end) {
 446                 start += sprintf(start, " %02x", *ptr);
 447                 ptr++; leng--;
 448         }
 449         *start++ = '\n';
 450         return start;
 451 }
 452
 453 static char *usb_dump_string(char *start, char *end,
 454                              const struct usb_device *dev, char *id, int index)
 455 {
 456         if (start > end)
 457                 return start;
 458         start += sprintf(start, "Interface:");
 459         if (index <= dev->maxstring && dev->stringindex &&
 460             dev->stringindex[index])
 461                 start += sprintf(start, "%s: %.100s ", id,
 462                                  dev->stringindex[index]);
 463         return start;
 464 }
 465
 466 #endif /* PROC_EXTRA */
 467
 468 /*****************************************************************/
 469
 470 /* This is a recursive function. Parameters:
 471  * buffer - the user-space buffer to write data into
 472  * nbytes - the maximum number of bytes to write
 473  * skip_bytes - the number of bytes to skip before writing anything
 474  * file_offset - the offset into the devices file on completion
 475  * The caller must own the device lock.
 476  */
 477 static ssize_t usb_device_dump(char __user **buffer, size_t *nbytes,
 478                                loff_t *skip_bytes, loff_t *file_offset,
 479                                struct usb_device *usbdev, struct usb_bus *bus,
 480                                int level, int index, int count)
 481 {
 482         int chix;
 483         int ret, cnt = 0;
 484         int parent_devnum = 0;
 485         char *pages_start, *data_end, *speed;
 486         unsigned int length;
 487         ssize_t total_written = 0;
 488
 489         /* don't bother with anything else if we're not writing any data */
 490         if (*nbytes <= 0)
 491                 return 0;
 492
 493         if (level > MAX_TOPO_LEVEL)
 494                 return 0;
 495         /* allocate 2^1 pages = 8K (on i386);
 496          * should be more than enough for one device */
 497         pages_start = (char *)__get_free_pages(GFP_KERNEL, 1);
 498         if (!pages_start)
 499                 return -ENOMEM;
 500
 501         if (usbdev->parent && usbdev->parent->devnum != -1)
 502                 parent_devnum = usbdev->parent->devnum;
 503         /*
 504          * So the root hub's parent is 0 and any device that is
 505          * plugged into the root hub has a parent of 0.
 506          */
 507         switch (usbdev->speed) {
 508         case USB_SPEED_LOW:
 509                 speed = "1.5"; break;
 510         case USB_SPEED_UNKNOWN:         /* usb 1.1 root hub code */
 511         case USB_SPEED_FULL:
 512                 speed = "12 "; break;
 513         case USB_SPEED_HIGH:
 514                 speed = "480"; break;
 515         default:
 516                 speed = "?? ";
 517         }
 518         data_end = pages_start + sprintf(pages_start, format_topo,
 519                         bus->busnum, level, parent_devnum,
 520                         index, count, usbdev->devnum,
 521                         speed, usbdev->maxchild);
 522         /*
 523          * level = topology-tier level;
 524          * parent_devnum = parent device number;
 525          * index = parent's connector number;
 526          * count = device count at this level
 527          */
 528         /* If this is the root hub, display the bandwidth information */
 529         if (level == 0) {
 530                 int     max;
 531
 532                 /* high speed reserves 80%, full/low reserves 90% */
 533                 if (usbdev->speed == USB_SPEED_HIGH)
 534                         max = 800;
 535                 else
 536                         max = FRAME_TIME_MAX_USECS_ALLOC;
 537
 538                 /* report "average" periodic allocation over a microsecond.
 539                  * the schedules are actually bursty, HCDs need to deal with
 540                  * that and just compute/report this average.
 541                  */
 542                 data_end += sprintf(data_end, format_bandwidth,
 543                                 bus->bandwidth_allocated, max,
 544                                 (100 * bus->bandwidth_allocated + max / 2)
 545                                         / max,
 546                                 bus->bandwidth_int_reqs,
 547                                 bus->bandwidth_isoc_reqs);
 548
 549         }
 550         data_end = usb_dump_desc(data_end, pages_start + (2 * PAGE_SIZE) - 256,
 551                                  usbdev);
 552
 553         if (data_end > (pages_start + (2 * PAGE_SIZE) - 256))
 554                 data_end += sprintf(data_end, "(truncated)\n");
 555
 556         length = data_end - pages_start;
 557         /* if we can start copying some data to the user */
 558         if (length > *skip_bytes) {
 559                 length -= *skip_bytes;
 560                 if (length > *nbytes)
 561                         length = *nbytes;
 562                 if (copy_to_user(*buffer, pages_start + *skip_bytes, length)) {
 563                         free_pages((unsigned long)pages_start, 1);
 564                         return -EFAULT;
 565                 }
 566                 *nbytes -= length;
 567                 *file_offset += length;
 568                 total_written += length;
 569                 *buffer += length;
 570                 *skip_bytes = 0;
 571         } else
 572                 *skip_bytes -= length;
 573
 574         free_pages((unsigned long)pages_start, 1);
 575
 576         /* Now look at all of this device's children. */
 577         for (chix = 0; chix < usbdev->maxchild; chix++) {
 578                 struct usb_device *childdev = usbdev->children[chix];
 579
 580                 if (childdev) {
 581                         usb_lock_device(childdev);
 582                         ret = usb_device_dump(buffer, nbytes, skip_bytes,
 583                                               file_offset, childdev, bus,
 584                                               level + 1, chix, ++cnt);
 585                         usb_unlock_device(childdev);
 586                         if (ret == -EFAULT)
 587                                 return total_written;
 588                         total_written += ret;
 589                 }
 590         }
 591         return total_written;
 592 }
 593
 594 static ssize_t usb_device_read(struct file *file, char __user *buf,
 595                                size_t nbytes, loff_t *ppos)
 596 {
 597         struct usb_bus *bus;
 598         ssize_t ret, total_written = 0;
 599         loff_t skip_bytes = *ppos;
 600
 601         if (*ppos < 0)
 602                 return -EINVAL;
 603         if (nbytes <= 0)
 604                 return 0;
 605         if (!access_ok(VERIFY_WRITE, buf, nbytes))
 606                 return -EFAULT;
 607
 608         mutex_lock(&usb_bus_list_lock);
 609         /* print devices for all busses */
 610         list_for_each_entry(bus, &usb_bus_list, bus_list) {
 611                 /* recurse through all children of the root hub */
 612                 if (!bus->root_hub)
 613                         continue;
 614                 usb_lock_device(bus->root_hub);
 615                 ret = usb_device_dump(&buf, &nbytes, &skip_bytes, ppos,
 616                                       bus->root_hub, bus, 0, 0, 0);
 617                 usb_unlock_device(bus->root_hub);
 618                 if (ret < 0) {
 619                         mutex_unlock(&usb_bus_list_lock);
 620                         return ret;
 621                 }
 622                 total_written += ret;
 623         }
 624         mutex_unlock(&usb_bus_list_lock);
 625         return total_written;
 626 }
 627
 628 /* Kernel lock for "lastev" protection */
 629 static unsigned int usb_device_poll(struct file *file,
 630                                     struct poll_table_struct *wait)
 631 {
 632         struct usb_device_status *st = file->private_data;
 633         unsigned int mask = 0;
 634
 635         lock_kernel();
 636         if (!st) {
 637                 st = kmalloc(sizeof(struct usb_device_status), GFP_KERNEL);
 638
 639                 /* we may have dropped BKL -
 640                  * need to check for having lost the race */
 641                 if (file->private_data) {
 642                         kfree(st);
 643                         st = file->private_data;
 644                         goto lost_race;
 645                 }
 646                 /* we haven't lost - check for allocation failure now */
 647                 if (!st) {
 648                         unlock_kernel();
 649                         return POLLIN;
 650                 }
 651
 652                 /*
 653                  * need to prevent the module from being unloaded, since
 654                  * proc_unregister does not call the release method and
 655                  * we would have a memory leak
 656                  */
 657                 st->lastev = conndiscevcnt;
 658                 file->private_data = st;
 659                 mask = POLLIN;
 660         }
 661 lost_race:
 662         if (file->f_mode & FMODE_READ)
 663                 poll_wait(file, &deviceconndiscwq, wait);
 664         if (st->lastev != conndiscevcnt)
 665                 mask |= POLLIN;
 666         st->lastev = conndiscevcnt;
 667         unlock_kernel();
 668         return mask;
 669 }
 670
 671 static int usb_device_open(struct inode *inode, struct file *file)
 672 {
 673         file->private_data = NULL;
 674         return 0;
 675 }
 676
 677 static int usb_device_release(struct inode *inode, struct file *file)
 678 {
 679         kfree(file->private_data);
 680         file->private_data = NULL;
 681         return 0;
 682 }
 683
 684 static loff_t usb_device_lseek(struct file *file, loff_t offset, int orig)
 685 {
 686         loff_t ret;
 687
 688         lock_kernel();
 689
 690         switch (orig) {
 691         case 0:
 692                 file->f_pos = offset;
 693                 ret = file->f_pos;
 694                 break;
 695         case 1:
 696                 file->f_pos += offset;
 697                 ret = file->f_pos;
 698                 break;
 699         case 2:
 700         default:
 701                 ret = -EINVAL;
 702         }
 703
 704         unlock_kernel();
 705         return ret;
 706 }
 707
 708 const struct file_operations usbfs_devices_fops = {
 709         .llseek =       usb_device_lseek,
 710         .read =         usb_device_read,
 711         .poll =         usb_device_poll,
 712         .open =         usb_device_open,
 713         .release =      usb_device_release,
 714 };