1 /* 2 * User-space I/O driver support for HID subsystem 3 * Copyright (c) 2012 David Herrmann 4 */ 5 6 /* 7 * This program is free software; you can redistribute it and/or modify it 8 * under the terms of the GNU General Public License as published by the Free 9 * Software Foundation; either version 2 of the License, or (at your option) 10 * any later version. 11 */ 12 13 #include <linux/atomic.h> 14 #include <linux/compat.h> 15 #include <linux/cred.h> 16 #include <linux/device.h> 17 #include <linux/fs.h> 18 #include <linux/hid.h> 19 #include <linux/input.h> 20 #include <linux/miscdevice.h> 21 #include <linux/module.h> 22 #include <linux/mutex.h> 23 #include <linux/poll.h> 24 #include <linux/sched.h> 25 #include <linux/spinlock.h> 26 #include <linux/uhid.h> 27 #include <linux/wait.h> 28 29 #define UHID_NAME "uhid" 30 #define UHID_BUFSIZE 32 31 32 struct uhid_device { 33 struct mutex devlock; 34 bool running; 35 36 __u8 *rd_data; 37 uint rd_size; 38 39 struct hid_device *hid; 40 struct uhid_event input_buf; 41 42 wait_queue_head_t waitq; 43 spinlock_t qlock; 44 __u8 head; 45 __u8 tail; 46 struct uhid_event *outq[UHID_BUFSIZE]; 47 48 /* blocking GET_REPORT support; state changes protected by qlock */ 49 struct mutex report_lock; 50 wait_queue_head_t report_wait; 51 bool report_running; 52 u32 report_id; 53 u32 report_type; 54 struct uhid_event report_buf; 55 struct work_struct worker; 56 }; 57 58 static struct miscdevice uhid_misc; 59 60 static void uhid_device_add_worker(struct work_struct *work) 61 { 62 struct uhid_device *uhid = container_of(work, struct uhid_device, worker); 63 int ret; 64 65 ret = hid_add_device(uhid->hid); 66 if (ret) { 67 hid_err(uhid->hid, "Cannot register HID device: error %d\n", ret); 68 69 hid_destroy_device(uhid->hid); 70 uhid->hid = NULL; 71 uhid->running = false; 72 } 73 } 74 75 static void uhid_queue(struct uhid_device *uhid, struct uhid_event *ev) 76 { 77 __u8 newhead; 78 79 newhead = (uhid->head + 1) % UHID_BUFSIZE; 80 81 if (newhead != uhid->tail) { 82 uhid->outq[uhid->head] = ev; 83 uhid->head = newhead; 84 wake_up_interruptible(&uhid->waitq); 85 } else { 86 hid_warn(uhid->hid, "Output queue is full\n"); 87 kfree(ev); 88 } 89 } 90 91 static int uhid_queue_event(struct uhid_device *uhid, __u32 event) 92 { 93 unsigned long flags; 94 struct uhid_event *ev; 95 96 ev = kzalloc(sizeof(*ev), GFP_KERNEL); 97 if (!ev) 98 return -ENOMEM; 99 100 ev->type = event; 101 102 spin_lock_irqsave(&uhid->qlock, flags); 103 uhid_queue(uhid, ev); 104 spin_unlock_irqrestore(&uhid->qlock, flags); 105 106 return 0; 107 } 108 109 static int uhid_hid_start(struct hid_device *hid) 110 { 111 struct uhid_device *uhid = hid->driver_data; 112 struct uhid_event *ev; 113 unsigned long flags; 114 115 ev = kzalloc(sizeof(*ev), GFP_KERNEL); 116 if (!ev) 117 return -ENOMEM; 118 119 ev->type = UHID_START; 120 121 if (hid->report_enum[HID_FEATURE_REPORT].numbered) 122 ev->u.start.dev_flags |= UHID_DEV_NUMBERED_FEATURE_REPORTS; 123 if (hid->report_enum[HID_OUTPUT_REPORT].numbered) 124 ev->u.start.dev_flags |= UHID_DEV_NUMBERED_OUTPUT_REPORTS; 125 if (hid->report_enum[HID_INPUT_REPORT].numbered) 126 ev->u.start.dev_flags |= UHID_DEV_NUMBERED_INPUT_REPORTS; 127 128 spin_lock_irqsave(&uhid->qlock, flags); 129 uhid_queue(uhid, ev); 130 spin_unlock_irqrestore(&uhid->qlock, flags); 131 132 return 0; 133 } 134 135 static void uhid_hid_stop(struct hid_device *hid) 136 { 137 struct uhid_device *uhid = hid->driver_data; 138 139 hid->claimed = 0; 140 uhid_queue_event(uhid, UHID_STOP); 141 } 142 143 static int uhid_hid_open(struct hid_device *hid) 144 { 145 struct uhid_device *uhid = hid->driver_data; 146 147 return uhid_queue_event(uhid, UHID_OPEN); 148 } 149 150 static void uhid_hid_close(struct hid_device *hid) 151 { 152 struct uhid_device *uhid = hid->driver_data; 153 154 uhid_queue_event(uhid, UHID_CLOSE); 155 } 156 157 static int uhid_hid_parse(struct hid_device *hid) 158 { 159 struct uhid_device *uhid = hid->driver_data; 160 161 return hid_parse_report(hid, uhid->rd_data, uhid->rd_size); 162 } 163 164 /* must be called with report_lock held */ 165 static int __uhid_report_queue_and_wait(struct uhid_device *uhid, 166 struct uhid_event *ev, 167 __u32 *report_id) 168 { 169 unsigned long flags; 170 int ret; 171 172 spin_lock_irqsave(&uhid->qlock, flags); 173 *report_id = ++uhid->report_id; 174 uhid->report_type = ev->type + 1; 175 uhid->report_running = true; 176 uhid_queue(uhid, ev); 177 spin_unlock_irqrestore(&uhid->qlock, flags); 178 179 ret = wait_event_interruptible_timeout(uhid->report_wait, 180 !uhid->report_running || !uhid->running, 181 5 * HZ); 182 if (!ret || !uhid->running || uhid->report_running) 183 ret = -EIO; 184 else if (ret < 0) 185 ret = -ERESTARTSYS; 186 else 187 ret = 0; 188 189 uhid->report_running = false; 190 191 return ret; 192 } 193 194 static void uhid_report_wake_up(struct uhid_device *uhid, u32 id, 195 const struct uhid_event *ev) 196 { 197 unsigned long flags; 198 199 spin_lock_irqsave(&uhid->qlock, flags); 200 201 /* id for old report; drop it silently */ 202 if (uhid->report_type != ev->type || uhid->report_id != id) 203 goto unlock; 204 if (!uhid->report_running) 205 goto unlock; 206 207 memcpy(&uhid->report_buf, ev, sizeof(*ev)); 208 uhid->report_running = false; 209 wake_up_interruptible(&uhid->report_wait); 210 211 unlock: 212 spin_unlock_irqrestore(&uhid->qlock, flags); 213 } 214 215 static int uhid_hid_get_report(struct hid_device *hid, unsigned char rnum, 216 u8 *buf, size_t count, u8 rtype) 217 { 218 struct uhid_device *uhid = hid->driver_data; 219 struct uhid_get_report_reply_req *req; 220 struct uhid_event *ev; 221 int ret; 222 223 if (!uhid->running) 224 return -EIO; 225 226 ev = kzalloc(sizeof(*ev), GFP_KERNEL); 227 if (!ev) 228 return -ENOMEM; 229 230 ev->type = UHID_GET_REPORT; 231 ev->u.get_report.rnum = rnum; 232 ev->u.get_report.rtype = rtype; 233 234 ret = mutex_lock_interruptible(&uhid->report_lock); 235 if (ret) { 236 kfree(ev); 237 return ret; 238 } 239 240 /* this _always_ takes ownership of @ev */ 241 ret = __uhid_report_queue_and_wait(uhid, ev, &ev->u.get_report.id); 242 if (ret) 243 goto unlock; 244 245 req = &uhid->report_buf.u.get_report_reply; 246 if (req->err) { 247 ret = -EIO; 248 } else { 249 ret = min3(count, (size_t)req->size, (size_t)UHID_DATA_MAX); 250 memcpy(buf, req->data, ret); 251 } 252 253 unlock: 254 mutex_unlock(&uhid->report_lock); 255 return ret; 256 } 257 258 static int uhid_hid_set_report(struct hid_device *hid, unsigned char rnum, 259 const u8 *buf, size_t count, u8 rtype) 260 { 261 struct uhid_device *uhid = hid->driver_data; 262 struct uhid_event *ev; 263 int ret; 264 265 if (!uhid->running || count > UHID_DATA_MAX) 266 return -EIO; 267 268 ev = kzalloc(sizeof(*ev), GFP_KERNEL); 269 if (!ev) 270 return -ENOMEM; 271 272 ev->type = UHID_SET_REPORT; 273 ev->u.set_report.rnum = rnum; 274 ev->u.set_report.rtype = rtype; 275 ev->u.set_report.size = count; 276 memcpy(ev->u.set_report.data, buf, count); 277 278 ret = mutex_lock_interruptible(&uhid->report_lock); 279 if (ret) { 280 kfree(ev); 281 return ret; 282 } 283 284 /* this _always_ takes ownership of @ev */ 285 ret = __uhid_report_queue_and_wait(uhid, ev, &ev->u.set_report.id); 286 if (ret) 287 goto unlock; 288 289 if (uhid->report_buf.u.set_report_reply.err) 290 ret = -EIO; 291 else 292 ret = count; 293 294 unlock: 295 mutex_unlock(&uhid->report_lock); 296 return ret; 297 } 298 299 static int uhid_hid_raw_request(struct hid_device *hid, unsigned char reportnum, 300 __u8 *buf, size_t len, unsigned char rtype, 301 int reqtype) 302 { 303 u8 u_rtype; 304 305 switch (rtype) { 306 case HID_FEATURE_REPORT: 307 u_rtype = UHID_FEATURE_REPORT; 308 break; 309 case HID_OUTPUT_REPORT: 310 u_rtype = UHID_OUTPUT_REPORT; 311 break; 312 case HID_INPUT_REPORT: 313 u_rtype = UHID_INPUT_REPORT; 314 break; 315 default: 316 return -EINVAL; 317 } 318 319 switch (reqtype) { 320 case HID_REQ_GET_REPORT: 321 return uhid_hid_get_report(hid, reportnum, buf, len, u_rtype); 322 case HID_REQ_SET_REPORT: 323 return uhid_hid_set_report(hid, reportnum, buf, len, u_rtype); 324 default: 325 return -EIO; 326 } 327 } 328 329 static int uhid_hid_output_raw(struct hid_device *hid, __u8 *buf, size_t count, 330 unsigned char report_type) 331 { 332 struct uhid_device *uhid = hid->driver_data; 333 __u8 rtype; 334 unsigned long flags; 335 struct uhid_event *ev; 336 337 switch (report_type) { 338 case HID_FEATURE_REPORT: 339 rtype = UHID_FEATURE_REPORT; 340 break; 341 case HID_OUTPUT_REPORT: 342 rtype = UHID_OUTPUT_REPORT; 343 break; 344 default: 345 return -EINVAL; 346 } 347 348 if (count < 1 || count > UHID_DATA_MAX) 349 return -EINVAL; 350 351 ev = kzalloc(sizeof(*ev), GFP_KERNEL); 352 if (!ev) 353 return -ENOMEM; 354 355 ev->type = UHID_OUTPUT; 356 ev->u.output.size = count; 357 ev->u.output.rtype = rtype; 358 memcpy(ev->u.output.data, buf, count); 359 360 spin_lock_irqsave(&uhid->qlock, flags); 361 uhid_queue(uhid, ev); 362 spin_unlock_irqrestore(&uhid->qlock, flags); 363 364 return count; 365 } 366 367 static int uhid_hid_output_report(struct hid_device *hid, __u8 *buf, 368 size_t count) 369 { 370 return uhid_hid_output_raw(hid, buf, count, HID_OUTPUT_REPORT); 371 } 372 373 struct hid_ll_driver uhid_hid_driver = { 374 .start = uhid_hid_start, 375 .stop = uhid_hid_stop, 376 .open = uhid_hid_open, 377 .close = uhid_hid_close, 378 .parse = uhid_hid_parse, 379 .raw_request = uhid_hid_raw_request, 380 .output_report = uhid_hid_output_report, 381 }; 382 EXPORT_SYMBOL_GPL(uhid_hid_driver); 383 384 #ifdef CONFIG_COMPAT 385 386 /* Apparently we haven't stepped on these rakes enough times yet. */ 387 struct uhid_create_req_compat { 388 __u8 name[128]; 389 __u8 phys[64]; 390 __u8 uniq[64]; 391 392 compat_uptr_t rd_data; 393 __u16 rd_size; 394 395 __u16 bus; 396 __u32 vendor; 397 __u32 product; 398 __u32 version; 399 __u32 country; 400 } __attribute__((__packed__)); 401 402 static int uhid_event_from_user(const char __user *buffer, size_t len, 403 struct uhid_event *event) 404 { 405 if (in_compat_syscall()) { 406 u32 type; 407 408 if (get_user(type, buffer)) 409 return -EFAULT; 410 411 if (type == UHID_CREATE) { 412 /* 413 * This is our messed up request with compat pointer. 414 * It is largish (more than 256 bytes) so we better 415 * allocate it from the heap. 416 */ 417 struct uhid_create_req_compat *compat; 418 419 compat = kzalloc(sizeof(*compat), GFP_KERNEL); 420 if (!compat) 421 return -ENOMEM; 422 423 buffer += sizeof(type); 424 len -= sizeof(type); 425 if (copy_from_user(compat, buffer, 426 min(len, sizeof(*compat)))) { 427 kfree(compat); 428 return -EFAULT; 429 } 430 431 /* Shuffle the data over to proper structure */ 432 event->type = type; 433 434 memcpy(event->u.create.name, compat->name, 435 sizeof(compat->name)); 436 memcpy(event->u.create.phys, compat->phys, 437 sizeof(compat->phys)); 438 memcpy(event->u.create.uniq, compat->uniq, 439 sizeof(compat->uniq)); 440 441 event->u.create.rd_data = compat_ptr(compat->rd_data); 442 event->u.create.rd_size = compat->rd_size; 443 444 event->u.create.bus = compat->bus; 445 event->u.create.vendor = compat->vendor; 446 event->u.create.product = compat->product; 447 event->u.create.version = compat->version; 448 event->u.create.country = compat->country; 449 450 kfree(compat); 451 return 0; 452 } 453 /* All others can be copied directly */ 454 } 455 456 if (copy_from_user(event, buffer, min(len, sizeof(*event)))) 457 return -EFAULT; 458 459 return 0; 460 } 461 #else 462 static int uhid_event_from_user(const char __user *buffer, size_t len, 463 struct uhid_event *event) 464 { 465 if (copy_from_user(event, buffer, min(len, sizeof(*event)))) 466 return -EFAULT; 467 468 return 0; 469 } 470 #endif 471 472 static int uhid_dev_create2(struct uhid_device *uhid, 473 const struct uhid_event *ev) 474 { 475 struct hid_device *hid; 476 size_t rd_size, len; 477 void *rd_data; 478 int ret; 479 480 if (uhid->running) 481 return -EALREADY; 482 483 rd_size = ev->u.create2.rd_size; 484 if (rd_size <= 0 || rd_size > HID_MAX_DESCRIPTOR_SIZE) 485 return -EINVAL; 486 487 rd_data = kmemdup(ev->u.create2.rd_data, rd_size, GFP_KERNEL); 488 if (!rd_data) 489 return -ENOMEM; 490 491 uhid->rd_size = rd_size; 492 uhid->rd_data = rd_data; 493 494 hid = hid_allocate_device(); 495 if (IS_ERR(hid)) { 496 ret = PTR_ERR(hid); 497 goto err_free; 498 } 499 500 /* @hid is zero-initialized, strncpy() is correct, strlcpy() not */ 501 len = min(sizeof(hid->name), sizeof(ev->u.create2.name)) - 1; 502 strncpy(hid->name, ev->u.create2.name, len); 503 len = min(sizeof(hid->phys), sizeof(ev->u.create2.phys)) - 1; 504 strncpy(hid->phys, ev->u.create2.phys, len); 505 len = min(sizeof(hid->uniq), sizeof(ev->u.create2.uniq)) - 1; 506 strncpy(hid->uniq, ev->u.create2.uniq, len); 507 508 hid->ll_driver = &uhid_hid_driver; 509 hid->bus = ev->u.create2.bus; 510 hid->vendor = ev->u.create2.vendor; 511 hid->product = ev->u.create2.product; 512 hid->version = ev->u.create2.version; 513 hid->country = ev->u.create2.country; 514 hid->driver_data = uhid; 515 hid->dev.parent = uhid_misc.this_device; 516 517 uhid->hid = hid; 518 uhid->running = true; 519 520 /* Adding of a HID device is done through a worker, to allow HID drivers 521 * which use feature requests during .probe to work, without they would 522 * be blocked on devlock, which is held by uhid_char_write. 523 */ 524 schedule_work(&uhid->worker); 525 526 return 0; 527 528 err_free: 529 kfree(uhid->rd_data); 530 uhid->rd_data = NULL; 531 uhid->rd_size = 0; 532 return ret; 533 } 534 535 static int uhid_dev_create(struct uhid_device *uhid, 536 struct uhid_event *ev) 537 { 538 struct uhid_create_req orig; 539 540 orig = ev->u.create; 541 542 if (orig.rd_size <= 0 || orig.rd_size > HID_MAX_DESCRIPTOR_SIZE) 543 return -EINVAL; 544 if (copy_from_user(&ev->u.create2.rd_data, orig.rd_data, orig.rd_size)) 545 return -EFAULT; 546 547 memcpy(ev->u.create2.name, orig.name, sizeof(orig.name)); 548 memcpy(ev->u.create2.phys, orig.phys, sizeof(orig.phys)); 549 memcpy(ev->u.create2.uniq, orig.uniq, sizeof(orig.uniq)); 550 ev->u.create2.rd_size = orig.rd_size; 551 ev->u.create2.bus = orig.bus; 552 ev->u.create2.vendor = orig.vendor; 553 ev->u.create2.product = orig.product; 554 ev->u.create2.version = orig.version; 555 ev->u.create2.country = orig.country; 556 557 return uhid_dev_create2(uhid, ev); 558 } 559 560 static int uhid_dev_destroy(struct uhid_device *uhid) 561 { 562 if (!uhid->running) 563 return -EINVAL; 564 565 uhid->running = false; 566 wake_up_interruptible(&uhid->report_wait); 567 568 cancel_work_sync(&uhid->worker); 569 570 hid_destroy_device(uhid->hid); 571 kfree(uhid->rd_data); 572 573 return 0; 574 } 575 576 static int uhid_dev_input(struct uhid_device *uhid, struct uhid_event *ev) 577 { 578 if (!uhid->running) 579 return -EINVAL; 580 581 hid_input_report(uhid->hid, HID_INPUT_REPORT, ev->u.input.data, 582 min_t(size_t, ev->u.input.size, UHID_DATA_MAX), 0); 583 584 return 0; 585 } 586 587 static int uhid_dev_input2(struct uhid_device *uhid, struct uhid_event *ev) 588 { 589 if (!uhid->running) 590 return -EINVAL; 591 592 hid_input_report(uhid->hid, HID_INPUT_REPORT, ev->u.input2.data, 593 min_t(size_t, ev->u.input2.size, UHID_DATA_MAX), 0); 594 595 return 0; 596 } 597 598 static int uhid_dev_get_report_reply(struct uhid_device *uhid, 599 struct uhid_event *ev) 600 { 601 if (!uhid->running) 602 return -EINVAL; 603 604 uhid_report_wake_up(uhid, ev->u.get_report_reply.id, ev); 605 return 0; 606 } 607 608 static int uhid_dev_set_report_reply(struct uhid_device *uhid, 609 struct uhid_event *ev) 610 { 611 if (!uhid->running) 612 return -EINVAL; 613 614 uhid_report_wake_up(uhid, ev->u.set_report_reply.id, ev); 615 return 0; 616 } 617 618 static int uhid_char_open(struct inode *inode, struct file *file) 619 { 620 struct uhid_device *uhid; 621 622 uhid = kzalloc(sizeof(*uhid), GFP_KERNEL); 623 if (!uhid) 624 return -ENOMEM; 625 626 mutex_init(&uhid->devlock); 627 mutex_init(&uhid->report_lock); 628 spin_lock_init(&uhid->qlock); 629 init_waitqueue_head(&uhid->waitq); 630 init_waitqueue_head(&uhid->report_wait); 631 uhid->running = false; 632 INIT_WORK(&uhid->worker, uhid_device_add_worker); 633 634 file->private_data = uhid; 635 nonseekable_open(inode, file); 636 637 return 0; 638 } 639 640 static int uhid_char_release(struct inode *inode, struct file *file) 641 { 642 struct uhid_device *uhid = file->private_data; 643 unsigned int i; 644 645 uhid_dev_destroy(uhid); 646 647 for (i = 0; i < UHID_BUFSIZE; ++i) 648 kfree(uhid->outq[i]); 649 650 kfree(uhid); 651 652 return 0; 653 } 654 655 static ssize_t uhid_char_read(struct file *file, char __user *buffer, 656 size_t count, loff_t *ppos) 657 { 658 struct uhid_device *uhid = file->private_data; 659 int ret; 660 unsigned long flags; 661 size_t len; 662 663 /* they need at least the "type" member of uhid_event */ 664 if (count < sizeof(__u32)) 665 return -EINVAL; 666 667 try_again: 668 if (file->f_flags & O_NONBLOCK) { 669 if (uhid->head == uhid->tail) 670 return -EAGAIN; 671 } else { 672 ret = wait_event_interruptible(uhid->waitq, 673 uhid->head != uhid->tail); 674 if (ret) 675 return ret; 676 } 677 678 ret = mutex_lock_interruptible(&uhid->devlock); 679 if (ret) 680 return ret; 681 682 if (uhid->head == uhid->tail) { 683 mutex_unlock(&uhid->devlock); 684 goto try_again; 685 } else { 686 len = min(count, sizeof(**uhid->outq)); 687 if (copy_to_user(buffer, uhid->outq[uhid->tail], len)) { 688 ret = -EFAULT; 689 } else { 690 kfree(uhid->outq[uhid->tail]); 691 uhid->outq[uhid->tail] = NULL; 692 693 spin_lock_irqsave(&uhid->qlock, flags); 694 uhid->tail = (uhid->tail + 1) % UHID_BUFSIZE; 695 spin_unlock_irqrestore(&uhid->qlock, flags); 696 } 697 } 698 699 mutex_unlock(&uhid->devlock); 700 return ret ? ret : len; 701 } 702 703 static ssize_t uhid_char_write(struct file *file, const char __user *buffer, 704 size_t count, loff_t *ppos) 705 { 706 struct uhid_device *uhid = file->private_data; 707 int ret; 708 size_t len; 709 710 /* we need at least the "type" member of uhid_event */ 711 if (count < sizeof(__u32)) 712 return -EINVAL; 713 714 ret = mutex_lock_interruptible(&uhid->devlock); 715 if (ret) 716 return ret; 717 718 memset(&uhid->input_buf, 0, sizeof(uhid->input_buf)); 719 len = min(count, sizeof(uhid->input_buf)); 720 721 ret = uhid_event_from_user(buffer, len, &uhid->input_buf); 722 if (ret) 723 goto unlock; 724 725 switch (uhid->input_buf.type) { 726 case UHID_CREATE: 727 /* 728 * 'struct uhid_create_req' contains a __user pointer which is 729 * copied from, so it's unsafe to allow this with elevated 730 * privileges (e.g. from a setuid binary) or via kernel_write(). 731 */ 732 if (file->f_cred != current_cred() || uaccess_kernel()) { 733 pr_err_once("UHID_CREATE from different security context by process %d (%s), this is not allowed.\n", 734 task_tgid_vnr(current), current->comm); 735 ret = -EACCES; 736 goto unlock; 737 } 738 ret = uhid_dev_create(uhid, &uhid->input_buf); 739 break; 740 case UHID_CREATE2: 741 ret = uhid_dev_create2(uhid, &uhid->input_buf); 742 break; 743 case UHID_DESTROY: 744 ret = uhid_dev_destroy(uhid); 745 break; 746 case UHID_INPUT: 747 ret = uhid_dev_input(uhid, &uhid->input_buf); 748 break; 749 case UHID_INPUT2: 750 ret = uhid_dev_input2(uhid, &uhid->input_buf); 751 break; 752 case UHID_GET_REPORT_REPLY: 753 ret = uhid_dev_get_report_reply(uhid, &uhid->input_buf); 754 break; 755 case UHID_SET_REPORT_REPLY: 756 ret = uhid_dev_set_report_reply(uhid, &uhid->input_buf); 757 break; 758 default: 759 ret = -EOPNOTSUPP; 760 } 761 762 unlock: 763 mutex_unlock(&uhid->devlock); 764 765 /* return "count" not "len" to not confuse the caller */ 766 return ret ? ret : count; 767 } 768 769 static __poll_t uhid_char_poll(struct file *file, poll_table *wait) 770 { 771 struct uhid_device *uhid = file->private_data; 772 773 poll_wait(file, &uhid->waitq, wait); 774 775 if (uhid->head != uhid->tail) 776 return EPOLLIN | EPOLLRDNORM; 777 778 return 0; 779 } 780 781 static const struct file_operations uhid_fops = { 782 .owner = THIS_MODULE, 783 .open = uhid_char_open, 784 .release = uhid_char_release, 785 .read = uhid_char_read, 786 .write = uhid_char_write, 787 .poll = uhid_char_poll, 788 .llseek = no_llseek, 789 }; 790 791 static struct miscdevice uhid_misc = { 792 .fops = &uhid_fops, 793 .minor = UHID_MINOR, 794 .name = UHID_NAME, 795 }; 796 module_misc_device(uhid_misc); 797 798 MODULE_LICENSE("GPL"); 799 MODULE_AUTHOR("David Herrmann <dh.herrmann@gmail.com>"); 800 MODULE_DESCRIPTION("User-space I/O driver support for HID subsystem"); 801 MODULE_ALIAS_MISCDEV(UHID_MINOR); 802 MODULE_ALIAS("devname:" UHID_NAME); 803