devices.c 19 KB

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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>.
  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. #include <linux/fs.h>
  52. #include <linux/mm.h>
  53. #include <linux/gfp.h>
  54. #include <linux/poll.h>
  55. #include <linux/usb.h>
  56. #include <linux/usbdevice_fs.h>
  57. #include <linux/usb/hcd.h>
  58. #include <linux/mutex.h>
  59. #include <linux/uaccess.h>
  60. #include "usb.h"
  61. /* Define ALLOW_SERIAL_NUMBER if you want to see the serial number of devices */
  62. #define ALLOW_SERIAL_NUMBER
  63. static const char format_topo[] =
  64. /* T: Bus=dd Lev=dd Prnt=dd Port=dd Cnt=dd Dev#=ddd Spd=dddd MxCh=dd */
  65. "\nT: Bus=%2.2d Lev=%2.2d Prnt=%2.2d Port=%2.2d Cnt=%2.2d Dev#=%3d Spd=%-4s MxCh=%2d\n";
  66. static const char format_string_manufacturer[] =
  67. /* S: Manufacturer=xxxx */
  68. "S: Manufacturer=%.100s\n";
  69. static const char format_string_product[] =
  70. /* S: Product=xxxx */
  71. "S: Product=%.100s\n";
  72. #ifdef ALLOW_SERIAL_NUMBER
  73. static const char format_string_serialnumber[] =
  74. /* S: SerialNumber=xxxx */
  75. "S: SerialNumber=%.100s\n";
  76. #endif
  77. static const char format_bandwidth[] =
  78. /* B: Alloc=ddd/ddd us (xx%), #Int=ddd, #Iso=ddd */
  79. "B: Alloc=%3d/%3d us (%2d%%), #Int=%3d, #Iso=%3d\n";
  80. static const char format_device1[] =
  81. /* D: Ver=xx.xx Cls=xx(sssss) Sub=xx Prot=xx MxPS=dd #Cfgs=dd */
  82. "D: Ver=%2x.%02x Cls=%02x(%-5s) Sub=%02x Prot=%02x MxPS=%2d #Cfgs=%3d\n";
  83. static const char format_device2[] =
  84. /* P: Vendor=xxxx ProdID=xxxx Rev=xx.xx */
  85. "P: Vendor=%04x ProdID=%04x Rev=%2x.%02x\n";
  86. static const char format_config[] =
  87. /* C: #Ifs=dd Cfg#=dd Atr=xx MPwr=dddmA */
  88. "C:%c #Ifs=%2d Cfg#=%2d Atr=%02x MxPwr=%3dmA\n";
  89. static const char format_iad[] =
  90. /* A: FirstIf#=dd IfCount=dd Cls=xx(sssss) Sub=xx Prot=xx */
  91. "A: FirstIf#=%2d IfCount=%2d Cls=%02x(%-5s) Sub=%02x Prot=%02x\n";
  92. static const char format_iface[] =
  93. /* I: If#=dd Alt=dd #EPs=dd Cls=xx(sssss) Sub=xx Prot=xx Driver=xxxx*/
  94. "I:%c If#=%2d Alt=%2d #EPs=%2d Cls=%02x(%-5s) Sub=%02x Prot=%02x Driver=%s\n";
  95. static const char format_endpt[] =
  96. /* E: Ad=xx(s) Atr=xx(ssss) MxPS=dddd Ivl=D?s */
  97. "E: Ad=%02x(%c) Atr=%02x(%-4s) MxPS=%4d Ivl=%d%cs\n";
  98. /*
  99. * Need access to the driver and USB bus lists.
  100. * extern struct list_head usb_bus_list;
  101. * However, these will come from functions that return ptrs to each of them.
  102. */
  103. /*
  104. * Wait for an connect/disconnect event to happen. We initialize
  105. * the event counter with an odd number, and each event will increment
  106. * the event counter by two, so it will always _stay_ odd. That means
  107. * that it will never be zero, so "event 0" will never match a current
  108. * event, and thus 'poll' will always trigger as readable for the first
  109. * time it gets called.
  110. */
  111. static struct device_connect_event {
  112. atomic_t count;
  113. wait_queue_head_t wait;
  114. } device_event = {
  115. .count = ATOMIC_INIT(1),
  116. .wait = __WAIT_QUEUE_HEAD_INITIALIZER(device_event.wait)
  117. };
  118. struct class_info {
  119. int class;
  120. char *class_name;
  121. };
  122. static const struct class_info clas_info[] = {
  123. /* max. 5 chars. per name string */
  124. {USB_CLASS_PER_INTERFACE, ">ifc"},
  125. {USB_CLASS_AUDIO, "audio"},
  126. {USB_CLASS_COMM, "comm."},
  127. {USB_CLASS_HID, "HID"},
  128. {USB_CLASS_PHYSICAL, "PID"},
  129. {USB_CLASS_STILL_IMAGE, "still"},
  130. {USB_CLASS_PRINTER, "print"},
  131. {USB_CLASS_MASS_STORAGE, "stor."},
  132. {USB_CLASS_HUB, "hub"},
  133. {USB_CLASS_CDC_DATA, "data"},
  134. {USB_CLASS_CSCID, "scard"},
  135. {USB_CLASS_CONTENT_SEC, "c-sec"},
  136. {USB_CLASS_VIDEO, "video"},
  137. {USB_CLASS_WIRELESS_CONTROLLER, "wlcon"},
  138. {USB_CLASS_MISC, "misc"},
  139. {USB_CLASS_APP_SPEC, "app."},
  140. {USB_CLASS_VENDOR_SPEC, "vend."},
  141. {-1, "unk."} /* leave as last */
  142. };
  143. /*****************************************************************/
  144. void usbfs_conn_disc_event(void)
  145. {
  146. atomic_add(2, &device_event.count);
  147. wake_up(&device_event.wait);
  148. }
  149. static const char *class_decode(const int class)
  150. {
  151. int ix;
  152. for (ix = 0; clas_info[ix].class != -1; ix++)
  153. if (clas_info[ix].class == class)
  154. break;
  155. return clas_info[ix].class_name;
  156. }
  157. static char *usb_dump_endpoint_descriptor(int speed, char *start, char *end,
  158. const struct usb_endpoint_descriptor *desc)
  159. {
  160. char dir, unit, *type;
  161. unsigned interval, bandwidth = 1;
  162. if (start > end)
  163. return start;
  164. dir = usb_endpoint_dir_in(desc) ? 'I' : 'O';
  165. if (speed == USB_SPEED_HIGH) {
  166. switch (le16_to_cpu(desc->wMaxPacketSize) & (0x03 << 11)) {
  167. case 1 << 11:
  168. bandwidth = 2; break;
  169. case 2 << 11:
  170. bandwidth = 3; break;
  171. }
  172. }
  173. /* this isn't checking for illegal values */
  174. switch (usb_endpoint_type(desc)) {
  175. case USB_ENDPOINT_XFER_CONTROL:
  176. type = "Ctrl";
  177. if (speed == USB_SPEED_HIGH) /* uframes per NAK */
  178. interval = desc->bInterval;
  179. else
  180. interval = 0;
  181. dir = 'B'; /* ctrl is bidirectional */
  182. break;
  183. case USB_ENDPOINT_XFER_ISOC:
  184. type = "Isoc";
  185. interval = 1 << (desc->bInterval - 1);
  186. break;
  187. case USB_ENDPOINT_XFER_BULK:
  188. type = "Bulk";
  189. if (speed == USB_SPEED_HIGH && dir == 'O') /* uframes per NAK */
  190. interval = desc->bInterval;
  191. else
  192. interval = 0;
  193. break;
  194. case USB_ENDPOINT_XFER_INT:
  195. type = "Int.";
  196. if (speed == USB_SPEED_HIGH || speed == USB_SPEED_SUPER)
  197. interval = 1 << (desc->bInterval - 1);
  198. else
  199. interval = desc->bInterval;
  200. break;
  201. default: /* "can't happen" */
  202. return start;
  203. }
  204. interval *= (speed == USB_SPEED_HIGH ||
  205. speed == USB_SPEED_SUPER) ? 125 : 1000;
  206. if (interval % 1000)
  207. unit = 'u';
  208. else {
  209. unit = 'm';
  210. interval /= 1000;
  211. }
  212. start += sprintf(start, format_endpt, desc->bEndpointAddress, dir,
  213. desc->bmAttributes, type,
  214. (le16_to_cpu(desc->wMaxPacketSize) & 0x07ff) *
  215. bandwidth,
  216. interval, unit);
  217. return start;
  218. }
  219. static char *usb_dump_interface_descriptor(char *start, char *end,
  220. const struct usb_interface_cache *intfc,
  221. const struct usb_interface *iface,
  222. int setno)
  223. {
  224. const struct usb_interface_descriptor *desc;
  225. const char *driver_name = "";
  226. int active = 0;
  227. if (start > end)
  228. return start;
  229. desc = &intfc->altsetting[setno].desc;
  230. if (iface) {
  231. driver_name = (iface->dev.driver
  232. ? iface->dev.driver->name
  233. : "(none)");
  234. active = (desc == &iface->cur_altsetting->desc);
  235. }
  236. start += sprintf(start, format_iface,
  237. active ? '*' : ' ', /* mark active altsetting */
  238. desc->bInterfaceNumber,
  239. desc->bAlternateSetting,
  240. desc->bNumEndpoints,
  241. desc->bInterfaceClass,
  242. class_decode(desc->bInterfaceClass),
  243. desc->bInterfaceSubClass,
  244. desc->bInterfaceProtocol,
  245. driver_name);
  246. return start;
  247. }
  248. static char *usb_dump_interface(int speed, char *start, char *end,
  249. const struct usb_interface_cache *intfc,
  250. const struct usb_interface *iface, int setno)
  251. {
  252. const struct usb_host_interface *desc = &intfc->altsetting[setno];
  253. int i;
  254. start = usb_dump_interface_descriptor(start, end, intfc, iface, setno);
  255. for (i = 0; i < desc->desc.bNumEndpoints; i++) {
  256. if (start > end)
  257. return start;
  258. start = usb_dump_endpoint_descriptor(speed,
  259. start, end, &desc->endpoint[i].desc);
  260. }
  261. return start;
  262. }
  263. static char *usb_dump_iad_descriptor(char *start, char *end,
  264. const struct usb_interface_assoc_descriptor *iad)
  265. {
  266. if (start > end)
  267. return start;
  268. start += sprintf(start, format_iad,
  269. iad->bFirstInterface,
  270. iad->bInterfaceCount,
  271. iad->bFunctionClass,
  272. class_decode(iad->bFunctionClass),
  273. iad->bFunctionSubClass,
  274. iad->bFunctionProtocol);
  275. return start;
  276. }
  277. /* TBD:
  278. * 0. TBDs
  279. * 1. marking active interface altsettings (code lists all, but should mark
  280. * which ones are active, if any)
  281. */
  282. static char *usb_dump_config_descriptor(char *start, char *end,
  283. const struct usb_config_descriptor *desc,
  284. int active)
  285. {
  286. if (start > end)
  287. return start;
  288. start += sprintf(start, format_config,
  289. /* mark active/actual/current cfg. */
  290. active ? '*' : ' ',
  291. desc->bNumInterfaces,
  292. desc->bConfigurationValue,
  293. desc->bmAttributes,
  294. desc->bMaxPower * 2);
  295. return start;
  296. }
  297. static char *usb_dump_config(int speed, char *start, char *end,
  298. const struct usb_host_config *config, int active)
  299. {
  300. int i, j;
  301. struct usb_interface_cache *intfc;
  302. struct usb_interface *interface;
  303. if (start > end)
  304. return start;
  305. if (!config)
  306. /* getting these some in 2.3.7; none in 2.3.6 */
  307. return start + sprintf(start, "(null Cfg. desc.)\n");
  308. start = usb_dump_config_descriptor(start, end, &config->desc, active);
  309. for (i = 0; i < USB_MAXIADS; i++) {
  310. if (config->intf_assoc[i] == NULL)
  311. break;
  312. start = usb_dump_iad_descriptor(start, end,
  313. config->intf_assoc[i]);
  314. }
  315. for (i = 0; i < config->desc.bNumInterfaces; i++) {
  316. intfc = config->intf_cache[i];
  317. interface = config->interface[i];
  318. for (j = 0; j < intfc->num_altsetting; j++) {
  319. if (start > end)
  320. return start;
  321. start = usb_dump_interface(speed,
  322. start, end, intfc, interface, j);
  323. }
  324. }
  325. return start;
  326. }
  327. /*
  328. * Dump the different USB descriptors.
  329. */
  330. static char *usb_dump_device_descriptor(char *start, char *end,
  331. const struct usb_device_descriptor *desc)
  332. {
  333. u16 bcdUSB = le16_to_cpu(desc->bcdUSB);
  334. u16 bcdDevice = le16_to_cpu(desc->bcdDevice);
  335. if (start > end)
  336. return start;
  337. start += sprintf(start, format_device1,
  338. bcdUSB >> 8, bcdUSB & 0xff,
  339. desc->bDeviceClass,
  340. class_decode(desc->bDeviceClass),
  341. desc->bDeviceSubClass,
  342. desc->bDeviceProtocol,
  343. desc->bMaxPacketSize0,
  344. desc->bNumConfigurations);
  345. if (start > end)
  346. return start;
  347. start += sprintf(start, format_device2,
  348. le16_to_cpu(desc->idVendor),
  349. le16_to_cpu(desc->idProduct),
  350. bcdDevice >> 8, bcdDevice & 0xff);
  351. return start;
  352. }
  353. /*
  354. * Dump the different strings that this device holds.
  355. */
  356. static char *usb_dump_device_strings(char *start, char *end,
  357. struct usb_device *dev)
  358. {
  359. if (start > end)
  360. return start;
  361. if (dev->manufacturer)
  362. start += sprintf(start, format_string_manufacturer,
  363. dev->manufacturer);
  364. if (start > end)
  365. goto out;
  366. if (dev->product)
  367. start += sprintf(start, format_string_product, dev->product);
  368. if (start > end)
  369. goto out;
  370. #ifdef ALLOW_SERIAL_NUMBER
  371. if (dev->serial)
  372. start += sprintf(start, format_string_serialnumber,
  373. dev->serial);
  374. #endif
  375. out:
  376. return start;
  377. }
  378. static char *usb_dump_desc(char *start, char *end, struct usb_device *dev)
  379. {
  380. int i;
  381. if (start > end)
  382. return start;
  383. start = usb_dump_device_descriptor(start, end, &dev->descriptor);
  384. if (start > end)
  385. return start;
  386. start = usb_dump_device_strings(start, end, dev);
  387. for (i = 0; i < dev->descriptor.bNumConfigurations; i++) {
  388. if (start > end)
  389. return start;
  390. start = usb_dump_config(dev->speed,
  391. start, end, dev->config + i,
  392. /* active ? */
  393. (dev->config + i) == dev->actconfig);
  394. }
  395. return start;
  396. }
  397. #ifdef PROC_EXTRA /* TBD: may want to add this code later */
  398. static char *usb_dump_hub_descriptor(char *start, char *end,
  399. const struct usb_hub_descriptor *desc)
  400. {
  401. int leng = USB_DT_HUB_NONVAR_SIZE;
  402. unsigned char *ptr = (unsigned char *)desc;
  403. if (start > end)
  404. return start;
  405. start += sprintf(start, "Interface:");
  406. while (leng && start <= end) {
  407. start += sprintf(start, " %02x", *ptr);
  408. ptr++; leng--;
  409. }
  410. *start++ = '\n';
  411. return start;
  412. }
  413. static char *usb_dump_string(char *start, char *end,
  414. const struct usb_device *dev, char *id, int index)
  415. {
  416. if (start > end)
  417. return start;
  418. start += sprintf(start, "Interface:");
  419. if (index <= dev->maxstring && dev->stringindex &&
  420. dev->stringindex[index])
  421. start += sprintf(start, "%s: %.100s ", id,
  422. dev->stringindex[index]);
  423. return start;
  424. }
  425. #endif /* PROC_EXTRA */
  426. /*****************************************************************/
  427. /* This is a recursive function. Parameters:
  428. * buffer - the user-space buffer to write data into
  429. * nbytes - the maximum number of bytes to write
  430. * skip_bytes - the number of bytes to skip before writing anything
  431. * file_offset - the offset into the devices file on completion
  432. * The caller must own the device lock.
  433. */
  434. static ssize_t usb_device_dump(char __user **buffer, size_t *nbytes,
  435. loff_t *skip_bytes, loff_t *file_offset,
  436. struct usb_device *usbdev, struct usb_bus *bus,
  437. int level, int index, int count)
  438. {
  439. int chix;
  440. int ret, cnt = 0;
  441. int parent_devnum = 0;
  442. char *pages_start, *data_end, *speed;
  443. unsigned int length;
  444. ssize_t total_written = 0;
  445. /* don't bother with anything else if we're not writing any data */
  446. if (*nbytes <= 0)
  447. return 0;
  448. if (level > MAX_TOPO_LEVEL)
  449. return 0;
  450. /* allocate 2^1 pages = 8K (on i386);
  451. * should be more than enough for one device */
  452. pages_start = (char *)__get_free_pages(GFP_NOIO, 1);
  453. if (!pages_start)
  454. return -ENOMEM;
  455. if (usbdev->parent && usbdev->parent->devnum != -1)
  456. parent_devnum = usbdev->parent->devnum;
  457. /*
  458. * So the root hub's parent is 0 and any device that is
  459. * plugged into the root hub has a parent of 0.
  460. */
  461. switch (usbdev->speed) {
  462. case USB_SPEED_LOW:
  463. speed = "1.5"; break;
  464. case USB_SPEED_UNKNOWN: /* usb 1.1 root hub code */
  465. case USB_SPEED_FULL:
  466. speed = "12"; break;
  467. case USB_SPEED_WIRELESS: /* Wireless has no real fixed speed */
  468. case USB_SPEED_HIGH:
  469. speed = "480"; break;
  470. case USB_SPEED_SUPER:
  471. speed = "5000"; break;
  472. default:
  473. speed = "??";
  474. }
  475. data_end = pages_start + sprintf(pages_start, format_topo,
  476. bus->busnum, level, parent_devnum,
  477. index, count, usbdev->devnum,
  478. speed, usbdev->maxchild);
  479. /*
  480. * level = topology-tier level;
  481. * parent_devnum = parent device number;
  482. * index = parent's connector number;
  483. * count = device count at this level
  484. */
  485. /* If this is the root hub, display the bandwidth information */
  486. if (level == 0) {
  487. int max;
  488. /* super/high speed reserves 80%, full/low reserves 90% */
  489. if (usbdev->speed == USB_SPEED_HIGH ||
  490. usbdev->speed == USB_SPEED_SUPER)
  491. max = 800;
  492. else
  493. max = FRAME_TIME_MAX_USECS_ALLOC;
  494. /* report "average" periodic allocation over a microsecond.
  495. * the schedules are actually bursty, HCDs need to deal with
  496. * that and just compute/report this average.
  497. */
  498. data_end += sprintf(data_end, format_bandwidth,
  499. bus->bandwidth_allocated, max,
  500. (100 * bus->bandwidth_allocated + max / 2)
  501. / max,
  502. bus->bandwidth_int_reqs,
  503. bus->bandwidth_isoc_reqs);
  504. }
  505. data_end = usb_dump_desc(data_end, pages_start + (2 * PAGE_SIZE) - 256,
  506. usbdev);
  507. if (data_end > (pages_start + (2 * PAGE_SIZE) - 256))
  508. data_end += sprintf(data_end, "(truncated)\n");
  509. length = data_end - pages_start;
  510. /* if we can start copying some data to the user */
  511. if (length > *skip_bytes) {
  512. length -= *skip_bytes;
  513. if (length > *nbytes)
  514. length = *nbytes;
  515. if (copy_to_user(*buffer, pages_start + *skip_bytes, length)) {
  516. free_pages((unsigned long)pages_start, 1);
  517. return -EFAULT;
  518. }
  519. *nbytes -= length;
  520. *file_offset += length;
  521. total_written += length;
  522. *buffer += length;
  523. *skip_bytes = 0;
  524. } else
  525. *skip_bytes -= length;
  526. free_pages((unsigned long)pages_start, 1);
  527. /* Now look at all of this device's children. */
  528. for (chix = 0; chix < usbdev->maxchild; chix++) {
  529. struct usb_device *childdev = usbdev->children[chix];
  530. if (childdev) {
  531. usb_lock_device(childdev);
  532. ret = usb_device_dump(buffer, nbytes, skip_bytes,
  533. file_offset, childdev, bus,
  534. level + 1, chix, ++cnt);
  535. usb_unlock_device(childdev);
  536. if (ret == -EFAULT)
  537. return total_written;
  538. total_written += ret;
  539. }
  540. }
  541. return total_written;
  542. }
  543. static ssize_t usb_device_read(struct file *file, char __user *buf,
  544. size_t nbytes, loff_t *ppos)
  545. {
  546. struct usb_bus *bus;
  547. ssize_t ret, total_written = 0;
  548. loff_t skip_bytes = *ppos;
  549. if (*ppos < 0)
  550. return -EINVAL;
  551. if (nbytes <= 0)
  552. return 0;
  553. if (!access_ok(VERIFY_WRITE, buf, nbytes))
  554. return -EFAULT;
  555. mutex_lock(&usb_bus_list_lock);
  556. /* print devices for all busses */
  557. list_for_each_entry(bus, &usb_bus_list, bus_list) {
  558. /* recurse through all children of the root hub */
  559. if (!bus->root_hub)
  560. continue;
  561. usb_lock_device(bus->root_hub);
  562. ret = usb_device_dump(&buf, &nbytes, &skip_bytes, ppos,
  563. bus->root_hub, bus, 0, 0, 0);
  564. usb_unlock_device(bus->root_hub);
  565. if (ret < 0) {
  566. mutex_unlock(&usb_bus_list_lock);
  567. return ret;
  568. }
  569. total_written += ret;
  570. }
  571. mutex_unlock(&usb_bus_list_lock);
  572. return total_written;
  573. }
  574. /* Kernel lock for "lastev" protection */
  575. static unsigned int usb_device_poll(struct file *file,
  576. struct poll_table_struct *wait)
  577. {
  578. unsigned int event_count;
  579. poll_wait(file, &device_event.wait, wait);
  580. event_count = atomic_read(&device_event.count);
  581. if (file->f_version != event_count) {
  582. file->f_version = event_count;
  583. return POLLIN | POLLRDNORM;
  584. }
  585. return 0;
  586. }
  587. static loff_t usb_device_lseek(struct file *file, loff_t offset, int orig)
  588. {
  589. loff_t ret;
  590. mutex_lock(&file->f_dentry->d_inode->i_mutex);
  591. switch (orig) {
  592. case 0:
  593. file->f_pos = offset;
  594. ret = file->f_pos;
  595. break;
  596. case 1:
  597. file->f_pos += offset;
  598. ret = file->f_pos;
  599. break;
  600. case 2:
  601. default:
  602. ret = -EINVAL;
  603. }
  604. mutex_unlock(&file->f_dentry->d_inode->i_mutex);
  605. return ret;
  606. }
  607. const struct file_operations usbfs_devices_fops = {
  608. .llseek = usb_device_lseek,
  609. .read = usb_device_read,
  610. .poll = usb_device_poll,
  611. };