1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * User-space I/O driver support for HID subsystem 4 * Copyright (c) 2012 David Herrmann 5 */ 6 7 /* 8 */ 9 10 #include <linux/atomic.h> 11 #include <linux/compat.h> 12 #include <linux/cred.h> 13 #include <linux/device.h> 14 #include <linux/fs.h> 15 #include <linux/hid.h> 16 #include <linux/input.h> 17 #include <linux/miscdevice.h> 18 #include <linux/module.h> 19 #include <linux/mutex.h> 20 #include <linux/poll.h> 21 #include <linux/sched.h> 22 #include <linux/spinlock.h> 23 #include <linux/uhid.h> 24 #include <linux/wait.h> 25 26 #define UHID_NAME "uhid" 27 #define UHID_BUFSIZE 32 28 29 struct uhid_device { 30 struct mutex devlock; 31 bool running; 32 33 __u8 *rd_data; 34 uint rd_size; 35 36 struct hid_device *hid; 37 struct uhid_event input_buf; 38 39 wait_queue_head_t waitq; 40 spinlock_t qlock; 41 __u8 head; 42 __u8 tail; 43 struct uhid_event *outq[UHID_BUFSIZE]; 44 45 /* blocking GET_REPORT support; state changes protected by qlock */ 46 struct mutex report_lock; 47 wait_queue_head_t report_wait; 48 bool report_running; 49 u32 report_id; 50 u32 report_type; 51 struct uhid_event report_buf; 52 struct work_struct worker; 53 }; 54 55 static struct miscdevice uhid_misc; 56 57 static void uhid_device_add_worker(struct work_struct *work) 58 { 59 struct uhid_device *uhid = container_of(work, struct uhid_device, worker); 60 int ret; 61 62 ret = hid_add_device(uhid->hid); 63 if (ret) { 64 hid_err(uhid->hid, "Cannot register HID device: error %d\n", ret); 65 66 hid_destroy_device(uhid->hid); 67 uhid->hid = NULL; 68 uhid->running = false; 69 } 70 } 71 72 static void uhid_queue(struct uhid_device *uhid, struct uhid_event *ev) 73 { 74 __u8 newhead; 75 76 newhead = (uhid->head + 1) % UHID_BUFSIZE; 77 78 if (newhead != uhid->tail) { 79 uhid->outq[uhid->head] = ev; 80 uhid->head = newhead; 81 wake_up_interruptible(&uhid->waitq); 82 } else { 83 hid_warn(uhid->hid, "Output queue is full\n"); 84 kfree(ev); 85 } 86 } 87 88 static int uhid_queue_event(struct uhid_device *uhid, __u32 event) 89 { 90 unsigned long flags; 91 struct uhid_event *ev; 92 93 ev = kzalloc(sizeof(*ev), GFP_KERNEL); 94 if (!ev) 95 return -ENOMEM; 96 97 ev->type = event; 98 99 spin_lock_irqsave(&uhid->qlock, flags); 100 uhid_queue(uhid, ev); 101 spin_unlock_irqrestore(&uhid->qlock, flags); 102 103 return 0; 104 } 105 106 static int uhid_hid_start(struct hid_device *hid) 107 { 108 struct uhid_device *uhid = hid->driver_data; 109 struct uhid_event *ev; 110 unsigned long flags; 111 112 ev = kzalloc(sizeof(*ev), GFP_KERNEL); 113 if (!ev) 114 return -ENOMEM; 115 116 ev->type = UHID_START; 117 118 if (hid->report_enum[HID_FEATURE_REPORT].numbered) 119 ev->u.start.dev_flags |= UHID_DEV_NUMBERED_FEATURE_REPORTS; 120 if (hid->report_enum[HID_OUTPUT_REPORT].numbered) 121 ev->u.start.dev_flags |= UHID_DEV_NUMBERED_OUTPUT_REPORTS; 122 if (hid->report_enum[HID_INPUT_REPORT].numbered) 123 ev->u.start.dev_flags |= UHID_DEV_NUMBERED_INPUT_REPORTS; 124 125 spin_lock_irqsave(&uhid->qlock, flags); 126 uhid_queue(uhid, ev); 127 spin_unlock_irqrestore(&uhid->qlock, flags); 128 129 return 0; 130 } 131 132 static void uhid_hid_stop(struct hid_device *hid) 133 { 134 struct uhid_device *uhid = hid->driver_data; 135 136 hid->claimed = 0; 137 uhid_queue_event(uhid, UHID_STOP); 138 } 139 140 static int uhid_hid_open(struct hid_device *hid) 141 { 142 struct uhid_device *uhid = hid->driver_data; 143 144 return uhid_queue_event(uhid, UHID_OPEN); 145 } 146 147 static void uhid_hid_close(struct hid_device *hid) 148 { 149 struct uhid_device *uhid = hid->driver_data; 150 151 uhid_queue_event(uhid, UHID_CLOSE); 152 } 153 154 static int uhid_hid_parse(struct hid_device *hid) 155 { 156 struct uhid_device *uhid = hid->driver_data; 157 158 return hid_parse_report(hid, uhid->rd_data, uhid->rd_size); 159 } 160 161 /* must be called with report_lock held */ 162 static int __uhid_report_queue_and_wait(struct uhid_device *uhid, 163 struct uhid_event *ev, 164 __u32 *report_id) 165 { 166 unsigned long flags; 167 int ret; 168 169 spin_lock_irqsave(&uhid->qlock, flags); 170 *report_id = ++uhid->report_id; 171 uhid->report_type = ev->type + 1; 172 uhid->report_running = true; 173 uhid_queue(uhid, ev); 174 spin_unlock_irqrestore(&uhid->qlock, flags); 175 176 ret = wait_event_interruptible_timeout(uhid->report_wait, 177 !uhid->report_running || !uhid->running, 178 5 * HZ); 179 if (!ret || !uhid->running || uhid->report_running) 180 ret = -EIO; 181 else if (ret < 0) 182 ret = -ERESTARTSYS; 183 else 184 ret = 0; 185 186 uhid->report_running = false; 187 188 return ret; 189 } 190 191 static void uhid_report_wake_up(struct uhid_device *uhid, u32 id, 192 const struct uhid_event *ev) 193 { 194 unsigned long flags; 195 196 spin_lock_irqsave(&uhid->qlock, flags); 197 198 /* id for old report; drop it silently */ 199 if (uhid->report_type != ev->type || uhid->report_id != id) 200 goto unlock; 201 if (!uhid->report_running) 202 goto unlock; 203 204 memcpy(&uhid->report_buf, ev, sizeof(*ev)); 205 uhid->report_running = false; 206 wake_up_interruptible(&uhid->report_wait); 207 208 unlock: 209 spin_unlock_irqrestore(&uhid->qlock, flags); 210 } 211 212 static int uhid_hid_get_report(struct hid_device *hid, unsigned char rnum, 213 u8 *buf, size_t count, u8 rtype) 214 { 215 struct uhid_device *uhid = hid->driver_data; 216 struct uhid_get_report_reply_req *req; 217 struct uhid_event *ev; 218 int ret; 219 220 if (!uhid->running) 221 return -EIO; 222 223 ev = kzalloc(sizeof(*ev), GFP_KERNEL); 224 if (!ev) 225 return -ENOMEM; 226 227 ev->type = UHID_GET_REPORT; 228 ev->u.get_report.rnum = rnum; 229 ev->u.get_report.rtype = rtype; 230 231 ret = mutex_lock_interruptible(&uhid->report_lock); 232 if (ret) { 233 kfree(ev); 234 return ret; 235 } 236 237 /* this _always_ takes ownership of @ev */ 238 ret = __uhid_report_queue_and_wait(uhid, ev, &ev->u.get_report.id); 239 if (ret) 240 goto unlock; 241 242 req = &uhid->report_buf.u.get_report_reply; 243 if (req->err) { 244 ret = -EIO; 245 } else { 246 ret = min3(count, (size_t)req->size, (size_t)UHID_DATA_MAX); 247 memcpy(buf, req->data, ret); 248 } 249 250 unlock: 251 mutex_unlock(&uhid->report_lock); 252 return ret; 253 } 254 255 static int uhid_hid_set_report(struct hid_device *hid, unsigned char rnum, 256 const u8 *buf, size_t count, u8 rtype) 257 { 258 struct uhid_device *uhid = hid->driver_data; 259 struct uhid_event *ev; 260 int ret; 261 262 if (!uhid->running || count > UHID_DATA_MAX) 263 return -EIO; 264 265 ev = kzalloc(sizeof(*ev), GFP_KERNEL); 266 if (!ev) 267 return -ENOMEM; 268 269 ev->type = UHID_SET_REPORT; 270 ev->u.set_report.rnum = rnum; 271 ev->u.set_report.rtype = rtype; 272 ev->u.set_report.size = count; 273 memcpy(ev->u.set_report.data, buf, count); 274 275 ret = mutex_lock_interruptible(&uhid->report_lock); 276 if (ret) { 277 kfree(ev); 278 return ret; 279 } 280 281 /* this _always_ takes ownership of @ev */ 282 ret = __uhid_report_queue_and_wait(uhid, ev, &ev->u.set_report.id); 283 if (ret) 284 goto unlock; 285 286 if (uhid->report_buf.u.set_report_reply.err) 287 ret = -EIO; 288 else 289 ret = count; 290 291 unlock: 292 mutex_unlock(&uhid->report_lock); 293 return ret; 294 } 295 296 static int uhid_hid_raw_request(struct hid_device *hid, unsigned char reportnum, 297 __u8 *buf, size_t len, unsigned char rtype, 298 int reqtype) 299 { 300 u8 u_rtype; 301 302 switch (rtype) { 303 case HID_FEATURE_REPORT: 304 u_rtype = UHID_FEATURE_REPORT; 305 break; 306 case HID_OUTPUT_REPORT: 307 u_rtype = UHID_OUTPUT_REPORT; 308 break; 309 case HID_INPUT_REPORT: 310 u_rtype = UHID_INPUT_REPORT; 311 break; 312 default: 313 return -EINVAL; 314 } 315 316 switch (reqtype) { 317 case HID_REQ_GET_REPORT: 318 return uhid_hid_get_report(hid, reportnum, buf, len, u_rtype); 319 case HID_REQ_SET_REPORT: 320 return uhid_hid_set_report(hid, reportnum, buf, len, u_rtype); 321 default: 322 return -EIO; 323 } 324 } 325 326 static int uhid_hid_output_raw(struct hid_device *hid, __u8 *buf, size_t count, 327 unsigned char report_type) 328 { 329 struct uhid_device *uhid = hid->driver_data; 330 __u8 rtype; 331 unsigned long flags; 332 struct uhid_event *ev; 333 334 switch (report_type) { 335 case HID_FEATURE_REPORT: 336 rtype = UHID_FEATURE_REPORT; 337 break; 338 case HID_OUTPUT_REPORT: 339 rtype = UHID_OUTPUT_REPORT; 340 break; 341 default: 342 return -EINVAL; 343 } 344 345 if (count < 1 || count > UHID_DATA_MAX) 346 return -EINVAL; 347 348 ev = kzalloc(sizeof(*ev), GFP_KERNEL); 349 if (!ev) 350 return -ENOMEM; 351 352 ev->type = UHID_OUTPUT; 353 ev->u.output.size = count; 354 ev->u.output.rtype = rtype; 355 memcpy(ev->u.output.data, buf, count); 356 357 spin_lock_irqsave(&uhid->qlock, flags); 358 uhid_queue(uhid, ev); 359 spin_unlock_irqrestore(&uhid->qlock, flags); 360 361 return count; 362 } 363 364 static int uhid_hid_output_report(struct hid_device *hid, __u8 *buf, 365 size_t count) 366 { 367 return uhid_hid_output_raw(hid, buf, count, HID_OUTPUT_REPORT); 368 } 369 370 struct hid_ll_driver uhid_hid_driver = { 371 .start = uhid_hid_start, 372 .stop = uhid_hid_stop, 373 .open = uhid_hid_open, 374 .close = uhid_hid_close, 375 .parse = uhid_hid_parse, 376 .raw_request = uhid_hid_raw_request, 377 .output_report = uhid_hid_output_report, 378 }; 379 EXPORT_SYMBOL_GPL(uhid_hid_driver); 380 381 #ifdef CONFIG_COMPAT 382 383 /* Apparently we haven't stepped on these rakes enough times yet. */ 384 struct uhid_create_req_compat { 385 __u8 name[128]; 386 __u8 phys[64]; 387 __u8 uniq[64]; 388 389 compat_uptr_t rd_data; 390 __u16 rd_size; 391 392 __u16 bus; 393 __u32 vendor; 394 __u32 product; 395 __u32 version; 396 __u32 country; 397 } __attribute__((__packed__)); 398 399 static int uhid_event_from_user(const char __user *buffer, size_t len, 400 struct uhid_event *event) 401 { 402 if (in_compat_syscall()) { 403 u32 type; 404 405 if (get_user(type, buffer)) 406 return -EFAULT; 407 408 if (type == UHID_CREATE) { 409 /* 410 * This is our messed up request with compat pointer. 411 * It is largish (more than 256 bytes) so we better 412 * allocate it from the heap. 413 */ 414 struct uhid_create_req_compat *compat; 415 416 compat = kzalloc(sizeof(*compat), GFP_KERNEL); 417 if (!compat) 418 return -ENOMEM; 419 420 buffer += sizeof(type); 421 len -= sizeof(type); 422 if (copy_from_user(compat, buffer, 423 min(len, sizeof(*compat)))) { 424 kfree(compat); 425 return -EFAULT; 426 } 427 428 /* Shuffle the data over to proper structure */ 429 event->type = type; 430 431 memcpy(event->u.create.name, compat->name, 432 sizeof(compat->name)); 433 memcpy(event->u.create.phys, compat->phys, 434 sizeof(compat->phys)); 435 memcpy(event->u.create.uniq, compat->uniq, 436 sizeof(compat->uniq)); 437 438 event->u.create.rd_data = compat_ptr(compat->rd_data); 439 event->u.create.rd_size = compat->rd_size; 440 441 event->u.create.bus = compat->bus; 442 event->u.create.vendor = compat->vendor; 443 event->u.create.product = compat->product; 444 event->u.create.version = compat->version; 445 event->u.create.country = compat->country; 446 447 kfree(compat); 448 return 0; 449 } 450 /* All others can be copied directly */ 451 } 452 453 if (copy_from_user(event, buffer, min(len, sizeof(*event)))) 454 return -EFAULT; 455 456 return 0; 457 } 458 #else 459 static int uhid_event_from_user(const char __user *buffer, size_t len, 460 struct uhid_event *event) 461 { 462 if (copy_from_user(event, buffer, min(len, sizeof(*event)))) 463 return -EFAULT; 464 465 return 0; 466 } 467 #endif 468 469 static int uhid_dev_create2(struct uhid_device *uhid, 470 const struct uhid_event *ev) 471 { 472 struct hid_device *hid; 473 size_t rd_size, len; 474 void *rd_data; 475 int ret; 476 477 if (uhid->running) 478 return -EALREADY; 479 480 rd_size = ev->u.create2.rd_size; 481 if (rd_size <= 0 || rd_size > HID_MAX_DESCRIPTOR_SIZE) 482 return -EINVAL; 483 484 rd_data = kmemdup(ev->u.create2.rd_data, rd_size, GFP_KERNEL); 485 if (!rd_data) 486 return -ENOMEM; 487 488 uhid->rd_size = rd_size; 489 uhid->rd_data = rd_data; 490 491 hid = hid_allocate_device(); 492 if (IS_ERR(hid)) { 493 ret = PTR_ERR(hid); 494 goto err_free; 495 } 496 497 /* @hid is zero-initialized, strncpy() is correct, strlcpy() not */ 498 len = min(sizeof(hid->name), sizeof(ev->u.create2.name)) - 1; 499 strncpy(hid->name, ev->u.create2.name, len); 500 len = min(sizeof(hid->phys), sizeof(ev->u.create2.phys)) - 1; 501 strncpy(hid->phys, ev->u.create2.phys, len); 502 len = min(sizeof(hid->uniq), sizeof(ev->u.create2.uniq)) - 1; 503 strncpy(hid->uniq, ev->u.create2.uniq, len); 504 505 hid->ll_driver = &uhid_hid_driver; 506 hid->bus = ev->u.create2.bus; 507 hid->vendor = ev->u.create2.vendor; 508 hid->product = ev->u.create2.product; 509 hid->version = ev->u.create2.version; 510 hid->country = ev->u.create2.country; 511 hid->driver_data = uhid; 512 hid->dev.parent = uhid_misc.this_device; 513 514 uhid->hid = hid; 515 uhid->running = true; 516 517 /* Adding of a HID device is done through a worker, to allow HID drivers 518 * which use feature requests during .probe to work, without they would 519 * be blocked on devlock, which is held by uhid_char_write. 520 */ 521 schedule_work(&uhid->worker); 522 523 return 0; 524 525 err_free: 526 kfree(uhid->rd_data); 527 uhid->rd_data = NULL; 528 uhid->rd_size = 0; 529 return ret; 530 } 531 532 static int uhid_dev_create(struct uhid_device *uhid, 533 struct uhid_event *ev) 534 { 535 struct uhid_create_req orig; 536 537 orig = ev->u.create; 538 539 if (orig.rd_size <= 0 || orig.rd_size > HID_MAX_DESCRIPTOR_SIZE) 540 return -EINVAL; 541 if (copy_from_user(&ev->u.create2.rd_data, orig.rd_data, orig.rd_size)) 542 return -EFAULT; 543 544 memcpy(ev->u.create2.name, orig.name, sizeof(orig.name)); 545 memcpy(ev->u.create2.phys, orig.phys, sizeof(orig.phys)); 546 memcpy(ev->u.create2.uniq, orig.uniq, sizeof(orig.uniq)); 547 ev->u.create2.rd_size = orig.rd_size; 548 ev->u.create2.bus = orig.bus; 549 ev->u.create2.vendor = orig.vendor; 550 ev->u.create2.product = orig.product; 551 ev->u.create2.version = orig.version; 552 ev->u.create2.country = orig.country; 553 554 return uhid_dev_create2(uhid, ev); 555 } 556 557 static int uhid_dev_destroy(struct uhid_device *uhid) 558 { 559 if (!uhid->running) 560 return -EINVAL; 561 562 uhid->running = false; 563 wake_up_interruptible(&uhid->report_wait); 564 565 cancel_work_sync(&uhid->worker); 566 567 hid_destroy_device(uhid->hid); 568 kfree(uhid->rd_data); 569 570 return 0; 571 } 572 573 static int uhid_dev_input(struct uhid_device *uhid, struct uhid_event *ev) 574 { 575 if (!uhid->running) 576 return -EINVAL; 577 578 hid_input_report(uhid->hid, HID_INPUT_REPORT, ev->u.input.data, 579 min_t(size_t, ev->u.input.size, UHID_DATA_MAX), 0); 580 581 return 0; 582 } 583 584 static int uhid_dev_input2(struct uhid_device *uhid, struct uhid_event *ev) 585 { 586 if (!uhid->running) 587 return -EINVAL; 588 589 hid_input_report(uhid->hid, HID_INPUT_REPORT, ev->u.input2.data, 590 min_t(size_t, ev->u.input2.size, UHID_DATA_MAX), 0); 591 592 return 0; 593 } 594 595 static int uhid_dev_get_report_reply(struct uhid_device *uhid, 596 struct uhid_event *ev) 597 { 598 if (!uhid->running) 599 return -EINVAL; 600 601 uhid_report_wake_up(uhid, ev->u.get_report_reply.id, ev); 602 return 0; 603 } 604 605 static int uhid_dev_set_report_reply(struct uhid_device *uhid, 606 struct uhid_event *ev) 607 { 608 if (!uhid->running) 609 return -EINVAL; 610 611 uhid_report_wake_up(uhid, ev->u.set_report_reply.id, ev); 612 return 0; 613 } 614 615 static int uhid_char_open(struct inode *inode, struct file *file) 616 { 617 struct uhid_device *uhid; 618 619 uhid = kzalloc(sizeof(*uhid), GFP_KERNEL); 620 if (!uhid) 621 return -ENOMEM; 622 623 mutex_init(&uhid->devlock); 624 mutex_init(&uhid->report_lock); 625 spin_lock_init(&uhid->qlock); 626 init_waitqueue_head(&uhid->waitq); 627 init_waitqueue_head(&uhid->report_wait); 628 uhid->running = false; 629 INIT_WORK(&uhid->worker, uhid_device_add_worker); 630 631 file->private_data = uhid; 632 stream_open(inode, file); 633 634 return 0; 635 } 636 637 static int uhid_char_release(struct inode *inode, struct file *file) 638 { 639 struct uhid_device *uhid = file->private_data; 640 unsigned int i; 641 642 uhid_dev_destroy(uhid); 643 644 for (i = 0; i < UHID_BUFSIZE; ++i) 645 kfree(uhid->outq[i]); 646 647 kfree(uhid); 648 649 return 0; 650 } 651 652 static ssize_t uhid_char_read(struct file *file, char __user *buffer, 653 size_t count, loff_t *ppos) 654 { 655 struct uhid_device *uhid = file->private_data; 656 int ret; 657 unsigned long flags; 658 size_t len; 659 660 /* they need at least the "type" member of uhid_event */ 661 if (count < sizeof(__u32)) 662 return -EINVAL; 663 664 try_again: 665 if (file->f_flags & O_NONBLOCK) { 666 if (uhid->head == uhid->tail) 667 return -EAGAIN; 668 } else { 669 ret = wait_event_interruptible(uhid->waitq, 670 uhid->head != uhid->tail); 671 if (ret) 672 return ret; 673 } 674 675 ret = mutex_lock_interruptible(&uhid->devlock); 676 if (ret) 677 return ret; 678 679 if (uhid->head == uhid->tail) { 680 mutex_unlock(&uhid->devlock); 681 goto try_again; 682 } else { 683 len = min(count, sizeof(**uhid->outq)); 684 if (copy_to_user(buffer, uhid->outq[uhid->tail], len)) { 685 ret = -EFAULT; 686 } else { 687 kfree(uhid->outq[uhid->tail]); 688 uhid->outq[uhid->tail] = NULL; 689 690 spin_lock_irqsave(&uhid->qlock, flags); 691 uhid->tail = (uhid->tail + 1) % UHID_BUFSIZE; 692 spin_unlock_irqrestore(&uhid->qlock, flags); 693 } 694 } 695 696 mutex_unlock(&uhid->devlock); 697 return ret ? ret : len; 698 } 699 700 static ssize_t uhid_char_write(struct file *file, const char __user *buffer, 701 size_t count, loff_t *ppos) 702 { 703 struct uhid_device *uhid = file->private_data; 704 int ret; 705 size_t len; 706 707 /* we need at least the "type" member of uhid_event */ 708 if (count < sizeof(__u32)) 709 return -EINVAL; 710 711 ret = mutex_lock_interruptible(&uhid->devlock); 712 if (ret) 713 return ret; 714 715 memset(&uhid->input_buf, 0, sizeof(uhid->input_buf)); 716 len = min(count, sizeof(uhid->input_buf)); 717 718 ret = uhid_event_from_user(buffer, len, &uhid->input_buf); 719 if (ret) 720 goto unlock; 721 722 switch (uhid->input_buf.type) { 723 case UHID_CREATE: 724 /* 725 * 'struct uhid_create_req' contains a __user pointer which is 726 * copied from, so it's unsafe to allow this with elevated 727 * privileges (e.g. from a setuid binary) or via kernel_write(). 728 */ 729 if (file->f_cred != current_cred() || uaccess_kernel()) { 730 pr_err_once("UHID_CREATE from different security context by process %d (%s), this is not allowed.\n", 731 task_tgid_vnr(current), current->comm); 732 ret = -EACCES; 733 goto unlock; 734 } 735 ret = uhid_dev_create(uhid, &uhid->input_buf); 736 break; 737 case UHID_CREATE2: 738 ret = uhid_dev_create2(uhid, &uhid->input_buf); 739 break; 740 case UHID_DESTROY: 741 ret = uhid_dev_destroy(uhid); 742 break; 743 case UHID_INPUT: 744 ret = uhid_dev_input(uhid, &uhid->input_buf); 745 break; 746 case UHID_INPUT2: 747 ret = uhid_dev_input2(uhid, &uhid->input_buf); 748 break; 749 case UHID_GET_REPORT_REPLY: 750 ret = uhid_dev_get_report_reply(uhid, &uhid->input_buf); 751 break; 752 case UHID_SET_REPORT_REPLY: 753 ret = uhid_dev_set_report_reply(uhid, &uhid->input_buf); 754 break; 755 default: 756 ret = -EOPNOTSUPP; 757 } 758 759 unlock: 760 mutex_unlock(&uhid->devlock); 761 762 /* return "count" not "len" to not confuse the caller */ 763 return ret ? ret : count; 764 } 765 766 static __poll_t uhid_char_poll(struct file *file, poll_table *wait) 767 { 768 struct uhid_device *uhid = file->private_data; 769 770 poll_wait(file, &uhid->waitq, wait); 771 772 if (uhid->head != uhid->tail) 773 return EPOLLIN | EPOLLRDNORM; 774 775 return 0; 776 } 777 778 static const struct file_operations uhid_fops = { 779 .owner = THIS_MODULE, 780 .open = uhid_char_open, 781 .release = uhid_char_release, 782 .read = uhid_char_read, 783 .write = uhid_char_write, 784 .poll = uhid_char_poll, 785 .llseek = no_llseek, 786 }; 787 788 static struct miscdevice uhid_misc = { 789 .fops = &uhid_fops, 790 .minor = UHID_MINOR, 791 .name = UHID_NAME, 792 }; 793 module_misc_device(uhid_misc); 794 795 MODULE_LICENSE("GPL"); 796 MODULE_AUTHOR("David Herrmann <dh.herrmann@gmail.com>"); 797 MODULE_DESCRIPTION("User-space I/O driver support for HID subsystem"); 798 MODULE_ALIAS_MISCDEV(UHID_MINOR); 799 MODULE_ALIAS("devname:" UHID_NAME); 800