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  * $Id: devices.c,v 1.5 2000/01/11 13:58:21 tom Exp $
  51  */
  52
  53 #include <linux/fs.h>
  54 #include <linux/mm.h>
  55 #include <linux/slab.h>
  56 #include <linux/poll.h>
  57 #include <linux/usb.h>
  58 #include <linux/smp_lock.h>
  59 #include <linux/usbdevice_fs.h>
  60 #include <linux/mutex.h>
  61 #include <asm/uaccess.h>
  62
  63 #include "usb.h"
  64 #include "hcd.h"
  65
  66 #define MAX_TOPO_LEVEL          6
  67
  68 /* Define ALLOW_SERIAL_NUMBER if you want to see the serial number of devices */
  69 #define ALLOW_SERIAL_NUMBER
  70
  71 static const char *format_topo =
  72 /* T:  Bus=dd Lev=dd Prnt=dd Port=dd Cnt=dd Dev#=ddd Spd=ddd MxCh=dd */
  73 "\nT:  Bus=%2.2d Lev=%2.2d Prnt=%2.2d Port=%2.2d Cnt=%2.2d Dev#=%3d Spd=%3s MxCh=%2d\n";
  74
  75 static const char *format_string_manufacturer =
  76 /* S:  Manufacturer=xxxx */
  77   "S:  Manufacturer=%.100s\n";
  78
  79 static const char *format_string_product =
  80 /* S:  Product=xxxx */
  81   "S:  Product=%.100s\n";
  82
  83 #ifdef ALLOW_SERIAL_NUMBER
  84 static const char *format_string_serialnumber =
  85 /* S:  SerialNumber=xxxx */
  86   "S:  SerialNumber=%.100s\n";
  87 #endif
  88
  89 static const char *format_bandwidth =
  90 /* B:  Alloc=ddd/ddd us (xx%), #Int=ddd, #Iso=ddd */
  91   "B:  Alloc=%3d/%3d us (%2d%%), #Int=%3d, #Iso=%3d\n";
  92
  93 static const char *format_device1 =
  94 /* D:  Ver=xx.xx Cls=xx(sssss) Sub=xx Prot=xx MxPS=dd #Cfgs=dd */
  95   "D:  Ver=%2x.%02x Cls=%02x(%-5s) Sub=%02x Prot=%02x MxPS=%2d #Cfgs=%3d\n";
  96
  97 static const char *format_device2 =
  98 /* P:  Vendor=xxxx ProdID=xxxx Rev=xx.xx */
  99   "P:  Vendor=%04x ProdID=%04x Rev=%2x.%02x\n";
 100
 101 static const char *format_config =
 102 /* C:  #Ifs=dd Cfg#=dd Atr=xx MPwr=dddmA */
 103   "C:%c #Ifs=%2d Cfg#=%2d Atr=%02x MxPwr=%3dmA\n";
 104
 105 static const char *format_iad =
 106 /* A:  FirstIf#=dd IfCount=dd Cls=xx(sssss) Sub=xx Prot=xx */
 107   "A:  FirstIf#=%2d IfCount=%2d Cls=%02x(%-5s) Sub=%02x Prot=%02x\n";
 108
 109 static const char *format_iface =
 110 /* I:  If#=dd Alt=dd #EPs=dd Cls=xx(sssss) Sub=xx Prot=xx Driver=xxxx*/
 111   "I:%c If#=%2d Alt=%2d #EPs=%2d Cls=%02x(%-5s) Sub=%02x Prot=%02x Driver=%s\n";
 112
 113 static const char *format_endpt =
 114 /* E:  Ad=xx(s) Atr=xx(ssss) MxPS=dddd Ivl=D?s */
 115   "E:  Ad=%02x(%c) Atr=%02x(%-4s) MxPS=%4d Ivl=%d%cs\n";
 116
 117
 118 /*
 119  * Need access to the driver and USB bus lists.
 120  * extern struct list_head usb_bus_list;
 121  * However, these will come from functions that return ptrs to each of them.
 122  */
 123
 124 static DECLARE_WAIT_QUEUE_HEAD(deviceconndiscwq);
 125 static unsigned int conndiscevcnt;
 126
 127 /* this struct stores the poll state for <mountpoint>/devices pollers */
 128 struct usb_device_status {
 129         unsigned int lastev;
 130 };
 131
 132 struct class_info {
 133         int class;
 134         char *class_name;
 135 };
 136
 137 static const struct class_info clas_info[] =
 138 {                                       /* max. 5 chars. per name string */
 139         {USB_CLASS_PER_INTERFACE,       ">ifc"},
 140         {USB_CLASS_AUDIO,               "audio"},
 141         {USB_CLASS_COMM,                "comm."},
 142         {USB_CLASS_HID,                 "HID"},
 143         {USB_CLASS_HUB,                 "hub"},
 144         {USB_CLASS_PHYSICAL,            "PID"},
 145         {USB_CLASS_PRINTER,             "print"},
 146         {USB_CLASS_MASS_STORAGE,        "stor."},
 147         {USB_CLASS_CDC_DATA,            "data"},
 148         {USB_CLASS_APP_SPEC,            "app."},
 149         {USB_CLASS_VENDOR_SPEC,         "vend."},
 150         {USB_CLASS_STILL_IMAGE,         "still"},
 151         {USB_CLASS_CSCID,               "scard"},
 152         {USB_CLASS_CONTENT_SEC,         "c-sec"},
 153         {USB_CLASS_VIDEO,               "video"},
 154         {-1,                            "unk."}         /* leave as last */
 155 };
 156
 157 /*****************************************************************/
 158
 159 void usbfs_conn_disc_event(void)
 160 {
 161         conndiscevcnt++;
 162         wake_up(&deviceconndiscwq);
 163 }
 164
 165 static const char *class_decode(const int class)
 166 {
 167         int ix;
 168
 169         for (ix = 0; clas_info[ix].class != -1; ix++)
 170                 if (clas_info[ix].class == class)
 171                         break;
 172         return clas_info[ix].class_name;
 173 }
 174
 175 static char *usb_dump_endpoint_descriptor(int speed, char *start, char *end,
 176                                 const struct usb_endpoint_descriptor *desc)
 177 {
 178         char dir, unit, *type;
 179         unsigned interval, bandwidth = 1;
 180
 181         if (start > end)
 182                 return start;
 183
 184         dir = usb_endpoint_dir_in(desc) ? 'I' : 'O';
 185
 186         if (speed == USB_SPEED_HIGH) {
 187                 switch (le16_to_cpu(desc->wMaxPacketSize) & (0x03 << 11)) {
 188                 case 1 << 11:   bandwidth = 2; break;
 189                 case 2 << 11:   bandwidth = 3; break;
 190                 }
 191         }
 192
 193         /* this isn't checking for illegal values */
 194         switch (desc->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) {
 195         case USB_ENDPOINT_XFER_CONTROL:
 196                 type = "Ctrl";
 197                 if (speed == USB_SPEED_HIGH)    /* uframes per NAK */
 198                         interval = desc->bInterval;
 199                 else
 200                         interval = 0;
 201                 dir = 'B';                      /* ctrl is bidirectional */
 202                 break;
 203         case USB_ENDPOINT_XFER_ISOC:
 204                 type = "Isoc";
 205                 interval = 1 << (desc->bInterval - 1);
 206                 break;
 207         case USB_ENDPOINT_XFER_BULK:
 208                 type = "Bulk";
 209                 if (speed == USB_SPEED_HIGH && dir == 'O') /* uframes per NAK */
 210                         interval = desc->bInterval;
 211                 else
 212                         interval = 0;
 213                 break;
 214         case USB_ENDPOINT_XFER_INT:
 215                 type = "Int.";
 216                 if (speed == USB_SPEED_HIGH)
 217                         interval = 1 << (desc->bInterval - 1);
 218                 else
 219                         interval = desc->bInterval;
 220                 break;
 221         default:        /* "can't happen" */
 222                 return start;
 223         }
 224         interval *= (speed == USB_SPEED_HIGH) ? 125 : 1000;
 225         if (interval % 1000)
 226                 unit = 'u';
 227         else {
 228                 unit = 'm';
 229                 interval /= 1000;
 230         }
 231
 232         start += sprintf(start, format_endpt, desc->bEndpointAddress, dir,
 233                          desc->bmAttributes, type,
 234                          (le16_to_cpu(desc->wMaxPacketSize) & 0x07ff) *
 235                          bandwidth,
 236                          interval, unit);
 237         return start;
 238 }
 239
 240 static char *usb_dump_interface_descriptor(char *start, char *end,
 241                                         const struct usb_interface_cache *intfc,
 242                                         const struct usb_interface *iface,
 243                                         int setno)
 244 {
 245         const struct usb_interface_descriptor *desc;
 246         const char *driver_name = "";
 247         int active = 0;
 248
 249         if (start > end)
 250                 return start;
 251         desc = &intfc->altsetting[setno].desc;
 252         if (iface) {
 253                 driver_name = (iface->dev.driver
 254                                 ? iface->dev.driver->name
 255                                 : "(none)");
 256                 active = (desc == &iface->cur_altsetting->desc);
 257         }
 258         start += sprintf(start, format_iface,
 259                          active ? '*' : ' ',    /* mark active altsetting */
 260                          desc->bInterfaceNumber,
 261                          desc->bAlternateSetting,
 262                          desc->bNumEndpoints,
 263                          desc->bInterfaceClass,
 264                          class_decode(desc->bInterfaceClass),
 265                          desc->bInterfaceSubClass,
 266                          desc->bInterfaceProtocol,
 267                          driver_name);
 268         return start;
 269 }
 270
 271 static char *usb_dump_interface(int speed, char *start, char *end,
 272                                 const struct usb_interface_cache *intfc,
 273                                 const struct usb_interface *iface, int setno)
 274 {
 275         const struct usb_host_interface *desc = &intfc->altsetting[setno];
 276         int i;
 277
 278         start = usb_dump_interface_descriptor(start, end, intfc, iface, setno);
 279         for (i = 0; i < desc->desc.bNumEndpoints; i++) {
 280                 if (start > end)
 281                         return start;
 282                 start = usb_dump_endpoint_descriptor(speed,
 283                                 start, end, &desc->endpoint[i].desc);
 284         }
 285         return start;
 286 }
 287
 288 static char *usb_dump_iad_descriptor(char *start, char *end,
 289                         const struct usb_interface_assoc_descriptor *iad)
 290 {
 291         if (start > end)
 292                 return start;
 293         start += sprintf(start, format_iad,
 294                          iad->bFirstInterface,
 295                          iad->bInterfaceCount,
 296                          iad->bFunctionClass,
 297                          class_decode(iad->bFunctionClass),
 298                          iad->bFunctionSubClass,
 299                          iad->bFunctionProtocol);
 300         return start;
 301 }
 302
 303 /* TBD:
 304  * 0. TBDs
 305  * 1. marking active interface altsettings (code lists all, but should mark
 306  *    which ones are active, if any)
 307  */
 308 static char *usb_dump_config_descriptor(char *start, char *end,
 309                                 const struct usb_config_descriptor *desc,
 310                                 int active)
 311 {
 312         if (start > end)
 313                 return start;
 314         start += sprintf(start, format_config,
 315                          /* mark active/actual/current cfg. */
 316                          active ? '*' : ' ',
 317                          desc->bNumInterfaces,
 318                          desc->bConfigurationValue,
 319                          desc->bmAttributes,
 320                          desc->bMaxPower * 2);
 321         return start;
 322 }
 323
 324 static char *usb_dump_config(int speed, char *start, char *end,
 325                              const struct usb_host_config *config, int active)
 326 {
 327         int i, j;
 328         struct usb_interface_cache *intfc;
 329         struct usb_interface *interface;
 330
 331         if (start > end)
 332                 return start;
 333         if (!config)
 334                 /* getting these some in 2.3.7; none in 2.3.6 */
 335                 return start + sprintf(start, "(null Cfg. desc.)\n");
 336         start = usb_dump_config_descriptor(start, end, &config->desc, active);
 337         for (i = 0; i < USB_MAXIADS; i++) {
 338                 if (config->intf_assoc[i] == NULL)
 339                         break;
 340                 start = usb_dump_iad_descriptor(start, end,
 341                                         config->intf_assoc[i]);
 342         }
 343         for (i = 0; i < config->desc.bNumInterfaces; i++) {
 344                 intfc = config->intf_cache[i];
 345                 interface = config->interface[i];
 346                 for (j = 0; j < intfc->num_altsetting; j++) {
 347                         if (start > end)
 348                                 return start;
 349                         start = usb_dump_interface(speed,
 350                                 start, end, intfc, interface, j);
 351                 }
 352         }
 353         return start;
 354 }
 355
 356 /*
 357  * Dump the different USB descriptors.
 358  */
 359 static char *usb_dump_device_descriptor(char *start, char *end,
 360                                 const struct usb_device_descriptor *desc)
 361 {
 362         u16 bcdUSB = le16_to_cpu(desc->bcdUSB);
 363         u16 bcdDevice = le16_to_cpu(desc->bcdDevice);
 364
 365         if (start > end)
 366                 return start;
 367         start += sprintf(start, format_device1,
 368                           bcdUSB >> 8, bcdUSB & 0xff,
 369                           desc->bDeviceClass,
 370                           class_decode(desc->bDeviceClass),
 371                           desc->bDeviceSubClass,
 372                           desc->bDeviceProtocol,
 373                           desc->bMaxPacketSize0,
 374                           desc->bNumConfigurations);
 375         if (start > end)
 376                 return start;
 377         start += sprintf(start, format_device2,
 378                          le16_to_cpu(desc->idVendor),
 379                          le16_to_cpu(desc->idProduct),
 380                          bcdDevice >> 8, bcdDevice & 0xff);
 381         return start;
 382 }
 383
 384 /*
 385  * Dump the different strings that this device holds.
 386  */
 387 static char *usb_dump_device_strings(char *start, char *end,
 388                                      struct usb_device *dev)
 389 {
 390         if (start > end)
 391                 return start;
 392         if (dev->manufacturer)
 393                 start += sprintf(start, format_string_manufacturer,
 394                                  dev->manufacturer);
 395         if (start > end)
 396                 goto out;
 397         if (dev->product)
 398                 start += sprintf(start, format_string_product, dev->product);
 399         if (start > end)
 400                 goto out;
 401 #ifdef ALLOW_SERIAL_NUMBER
 402         if (dev->serial)
 403                 start += sprintf(start, format_string_serialnumber,
 404                                  dev->serial);
 405 #endif
 406  out:
 407         return start;
 408 }
 409
 410 static char *usb_dump_desc(char *start, char *end, struct usb_device *dev)
 411 {
 412         int i;
 413
 414         if (start > end)
 415                 return start;
 416
 417         start = usb_dump_device_descriptor(start, end, &dev->descriptor);
 418
 419         if (start > end)
 420                 return start;
 421
 422         start = usb_dump_device_strings(start, end, dev);
 423
 424         for (i = 0; i < dev->descriptor.bNumConfigurations; i++) {
 425                 if (start > end)
 426                         return start;
 427                 start = usb_dump_config(dev->speed,
 428                                 start, end, dev->config + i,
 429                                 /* active ? */
 430                                 (dev->config + i) == dev->actconfig);
 431         }
 432         return start;
 433 }
 434
 435
 436 #ifdef PROC_EXTRA /* TBD: may want to add this code later */
 437
 438 static char *usb_dump_hub_descriptor(char *start, char *end,
 439                                      const struct usb_hub_descriptor *desc)
 440 {
 441         int leng = USB_DT_HUB_NONVAR_SIZE;
 442         unsigned char *ptr = (unsigned char *)desc;
 443
 444         if (start > end)
 445                 return start;
 446         start += sprintf(start, "Interface:");
 447         while (leng && start <= end) {
 448                 start += sprintf(start, " %02x", *ptr);
 449                 ptr++; leng--;
 450         }
 451         *start++ = '\n';
 452         return start;
 453 }
 454
 455 static char *usb_dump_string(char *start, char *end,
 456                              const struct usb_device *dev, char *id, int index)
 457 {
 458         if (start > end)
 459                 return start;
 460         start += sprintf(start, "Interface:");
 461         if (index <= dev->maxstring && dev->stringindex &&
 462             dev->stringindex[index])
 463                 start += sprintf(start, "%s: %.100s ", id,
 464                                  dev->stringindex[index]);
 465         return start;
 466 }
 467
 468 #endif /* PROC_EXTRA */
 469
 470 /*****************************************************************/
 471
 472 /* This is a recursive function. Parameters:
 473  * buffer - the user-space buffer to write data into
 474  * nbytes - the maximum number of bytes to write
 475  * skip_bytes - the number of bytes to skip before writing anything
 476  * file_offset - the offset into the devices file on completion
 477  * The caller must own the device lock.
 478  */
 479 static ssize_t usb_device_dump(char __user **buffer, size_t *nbytes,
 480                                loff_t *skip_bytes, loff_t *file_offset,
 481                                struct usb_device *usbdev, struct usb_bus *bus,
 482                                int level, int index, int count)
 483 {
 484         int chix;
 485         int ret, cnt = 0;
 486         int parent_devnum = 0;
 487         char *pages_start, *data_end, *speed;
 488         unsigned int length;
 489         ssize_t total_written = 0;
 490
 491         /* don't bother with anything else if we're not writing any data */
 492         if (*nbytes <= 0)
 493                 return 0;
 494
 495         if (level > MAX_TOPO_LEVEL)
 496                 return 0;
 497         /* allocate 2^1 pages = 8K (on i386);
 498          * should be more than enough for one device */
 499         pages_start = (char *)__get_free_pages(GFP_KERNEL, 1);
 500         if (!pages_start)
 501                 return -ENOMEM;
 502
 503         if (usbdev->parent && usbdev->parent->devnum != -1)
 504                 parent_devnum = usbdev->parent->devnum;
 505         /*
 506          * So the root hub's parent is 0 and any device that is
 507          * plugged into the root hub has a parent of 0.
 508          */
 509         switch (usbdev->speed) {
 510         case USB_SPEED_LOW:
 511                 speed = "1.5"; break;
 512         case USB_SPEED_UNKNOWN:         /* usb 1.1 root hub code */
 513         case USB_SPEED_FULL:
 514                 speed = "12 "; break;
 515         case USB_SPEED_HIGH:
 516                 speed = "480"; break;
 517         default:
 518                 speed = "?? ";
 519         }
 520         data_end = pages_start + sprintf(pages_start, format_topo,
 521                         bus->busnum, level, parent_devnum,
 522                         index, count, usbdev->devnum,
 523                         speed, usbdev->maxchild);
 524         /*
 525          * level = topology-tier level;
 526          * parent_devnum = parent device number;
 527          * index = parent's connector number;
 528          * count = device count at this level
 529          */
 530         /* If this is the root hub, display the bandwidth information */
 531         if (level == 0) {
 532                 int     max;
 533
 534                 /* high speed reserves 80%, full/low reserves 90% */
 535                 if (usbdev->speed == USB_SPEED_HIGH)
 536                         max = 800;
 537                 else
 538                         max = FRAME_TIME_MAX_USECS_ALLOC;
 539
 540                 /* report "average" periodic allocation over a microsecond.
 541                  * the schedules are actually bursty, HCDs need to deal with
 542                  * that and just compute/report this average.
 543                  */
 544                 data_end += sprintf(data_end, format_bandwidth,
 545                                 bus->bandwidth_allocated, max,
 546                                 (100 * bus->bandwidth_allocated + max / 2)
 547                                         / max,
 548                                 bus->bandwidth_int_reqs,
 549                                 bus->bandwidth_isoc_reqs);
 550
 551         }
 552         data_end = usb_dump_desc(data_end, pages_start + (2 * PAGE_SIZE) - 256,
 553                                  usbdev);
 554
 555         if (data_end > (pages_start + (2 * PAGE_SIZE) - 256))
 556                 data_end += sprintf(data_end, "(truncated)\n");
 557
 558         length = data_end - pages_start;
 559         /* if we can start copying some data to the user */
 560         if (length > *skip_bytes) {
 561                 length -= *skip_bytes;
 562                 if (length > *nbytes)
 563                         length = *nbytes;
 564                 if (copy_to_user(*buffer, pages_start + *skip_bytes, length)) {
 565                         free_pages((unsigned long)pages_start, 1);
 566                         return -EFAULT;
 567                 }
 568                 *nbytes -= length;
 569                 *file_offset += length;
 570                 total_written += length;
 571                 *buffer += length;
 572                 *skip_bytes = 0;
 573         } else
 574                 *skip_bytes -= length;
 575
 576         free_pages((unsigned long)pages_start, 1);
 577
 578         /* Now look at all of this device's children. */
 579         for (chix = 0; chix < usbdev->maxchild; chix++) {
 580                 struct usb_device *childdev = usbdev->children[chix];
 581
 582                 if (childdev) {
 583                         usb_lock_device(childdev);
 584                         ret = usb_device_dump(buffer, nbytes, skip_bytes,
 585                                               file_offset, childdev, bus,
 586                                               level + 1, chix, ++cnt);
 587                         usb_unlock_device(childdev);
 588                         if (ret == -EFAULT)
 589                                 return total_written;
 590                         total_written += ret;
 591                 }
 592         }
 593         return total_written;
 594 }
 595
 596 static ssize_t usb_device_read(struct file *file, char __user *buf,
 597                                size_t nbytes, loff_t *ppos)
 598 {
 599         struct usb_bus *bus;
 600         ssize_t ret, total_written = 0;
 601         loff_t skip_bytes = *ppos;
 602
 603         if (*ppos < 0)
 604                 return -EINVAL;
 605         if (nbytes <= 0)
 606                 return 0;
 607         if (!access_ok(VERIFY_WRITE, buf, nbytes))
 608                 return -EFAULT;
 609
 610         mutex_lock(&usb_bus_list_lock);
 611         /* print devices for all busses */
 612         list_for_each_entry(bus, &usb_bus_list, bus_list) {
 613                 /* recurse through all children of the root hub */
 614                 if (!bus->root_hub)
 615                         continue;
 616                 usb_lock_device(bus->root_hub);
 617                 ret = usb_device_dump(&buf, &nbytes, &skip_bytes, ppos,
 618                                       bus->root_hub, bus, 0, 0, 0);
 619                 usb_unlock_device(bus->root_hub);
 620                 if (ret < 0) {
 621                         mutex_unlock(&usb_bus_list_lock);
 622                         return ret;
 623                 }
 624                 total_written += ret;
 625         }
 626         mutex_unlock(&usb_bus_list_lock);
 627         return total_written;
 628 }
 629
 630 /* Kernel lock for "lastev" protection */
 631 static unsigned int usb_device_poll(struct file *file,
 632                                     struct poll_table_struct *wait)
 633 {
 634         struct usb_device_status *st = file->private_data;
 635         unsigned int mask = 0;
 636
 637         lock_kernel();
 638         if (!st) {
 639                 st = kmalloc(sizeof(struct usb_device_status), GFP_KERNEL);
 640
 641                 /* we may have dropped BKL -
 642                  * need to check for having lost the race */
 643                 if (file->private_data) {
 644                         kfree(st);
 645                         st = file->private_data;
 646                         goto lost_race;
 647                 }
 648                 /* we haven't lost - check for allocation failure now */
 649                 if (!st) {
 650                         unlock_kernel();
 651                         return POLLIN;
 652                 }
 653
 654                 /*
 655                  * need to prevent the module from being unloaded, since
 656                  * proc_unregister does not call the release method and
 657                  * we would have a memory leak
 658                  */
 659                 st->lastev = conndiscevcnt;
 660                 file->private_data = st;
 661                 mask = POLLIN;
 662         }
 663 lost_race:
 664         if (file->f_mode & FMODE_READ)
 665                 poll_wait(file, &deviceconndiscwq, wait);
 666         if (st->lastev != conndiscevcnt)
 667                 mask |= POLLIN;
 668         st->lastev = conndiscevcnt;
 669         unlock_kernel();
 670         return mask;
 671 }
 672
 673 static int usb_device_open(struct inode *inode, struct file *file)
 674 {
 675         file->private_data = NULL;
 676         return 0;
 677 }
 678
 679 static int usb_device_release(struct inode *inode, struct file *file)
 680 {
 681         kfree(file->private_data);
 682         file->private_data = NULL;
 683         return 0;
 684 }
 685
 686 static loff_t usb_device_lseek(struct file *file, loff_t offset, int orig)
 687 {
 688         loff_t ret;
 689
 690         lock_kernel();
 691
 692         switch (orig) {
 693         case 0:
 694                 file->f_pos = offset;
 695                 ret = file->f_pos;
 696                 break;
 697         case 1:
 698                 file->f_pos += offset;
 699                 ret = file->f_pos;
 700                 break;
 701         case 2:
 702         default:
 703                 ret = -EINVAL;
 704         }
 705
 706         unlock_kernel();
 707         return ret;
 708 }
 709
 710 const struct file_operations usbfs_devices_fops = {
 711         .llseek =       usb_device_lseek,
 712         .read =         usb_device_read,
 713         .poll =         usb_device_poll,
 714         .open =         usb_device_open,
 715         .release =      usb_device_release,
 716 };