drivers/hid/uhid.c

   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/device.h>
  16 #include <linux/fs.h>
  17 #include <linux/hid.h>
  18 #include <linux/input.h>
  19 #include <linux/miscdevice.h>
  20 #include <linux/module.h>
  21 #include <linux/mutex.h>
  22 #include <linux/poll.h>
  23 #include <linux/sched.h>
  24 #include <linux/spinlock.h>
  25 #include <linux/uhid.h>
  26 #include <linux/wait.h>
  27
  28 #define UHID_NAME       "uhid"
  29 #define UHID_BUFSIZE    32
  30
  31 struct uhid_device {
  32         struct mutex devlock;
  33         bool running;
  34
  35         __u8 *rd_data;
  36         uint rd_size;
  37
  38         struct hid_device *hid;
  39         struct uhid_event input_buf;
  40
  41         wait_queue_head_t waitq;
  42         spinlock_t qlock;
  43         __u8 head;
  44         __u8 tail;
  45         struct uhid_event *outq[UHID_BUFSIZE];
  46
  47         /* blocking GET_REPORT support; state changes protected by qlock */
  48         struct mutex report_lock;
  49         wait_queue_head_t report_wait;
  50         bool report_running;
  51         u32 report_id;
  52         u32 report_type;
  53         struct uhid_event report_buf;
  54         struct work_struct worker;
  55 };
  56
  57 static struct miscdevice uhid_misc;
  58
  59 static void uhid_device_add_worker(struct work_struct *work)
  60 {
  61         struct uhid_device *uhid = container_of(work, struct uhid_device, worker);
  62         int ret;
  63
  64         ret = hid_add_device(uhid->hid);
  65         if (ret) {
  66                 hid_err(uhid->hid, "Cannot register HID device: error %d\n", ret);
  67
  68                 hid_destroy_device(uhid->hid);
  69                 uhid->hid = NULL;
  70                 uhid->running = false;
  71         }
  72 }
  73
  74 static void uhid_queue(struct uhid_device *uhid, struct uhid_event *ev)
  75 {
  76         __u8 newhead;
  77
  78         newhead = (uhid->head + 1) % UHID_BUFSIZE;
  79
  80         if (newhead != uhid->tail) {
  81                 uhid->outq[uhid->head] = ev;
  82                 uhid->head = newhead;
  83                 wake_up_interruptible(&uhid->waitq);
  84         } else {
  85                 hid_warn(uhid->hid, "Output queue is full\n");
  86                 kfree(ev);
  87         }
  88 }
  89
  90 static int uhid_queue_event(struct uhid_device *uhid, __u32 event)
  91 {
  92         unsigned long flags;
  93         struct uhid_event *ev;
  94
  95         ev = kzalloc(sizeof(*ev), GFP_KERNEL);
  96         if (!ev)
  97                 return -ENOMEM;
  98
  99         ev->type = event;
 100
 101         spin_lock_irqsave(&uhid->qlock, flags);
 102         uhid_queue(uhid, ev);
 103         spin_unlock_irqrestore(&uhid->qlock, flags);
 104
 105         return 0;
 106 }
 107
 108 static int uhid_hid_start(struct hid_device *hid)
 109 {
 110         struct uhid_device *uhid = hid->driver_data;
 111         struct uhid_event *ev;
 112         unsigned long flags;
 113
 114         ev = kzalloc(sizeof(*ev), GFP_KERNEL);
 115         if (!ev)
 116                 return -ENOMEM;
 117
 118         ev->type = UHID_START;
 119
 120         if (hid->report_enum[HID_FEATURE_REPORT].numbered)
 121                 ev->u.start.dev_flags |= UHID_DEV_NUMBERED_FEATURE_REPORTS;
 122         if (hid->report_enum[HID_OUTPUT_REPORT].numbered)
 123                 ev->u.start.dev_flags |= UHID_DEV_NUMBERED_OUTPUT_REPORTS;
 124         if (hid->report_enum[HID_INPUT_REPORT].numbered)
 125                 ev->u.start.dev_flags |= UHID_DEV_NUMBERED_INPUT_REPORTS;
 126
 127         spin_lock_irqsave(&uhid->qlock, flags);
 128         uhid_queue(uhid, ev);
 129         spin_unlock_irqrestore(&uhid->qlock, flags);
 130
 131         return 0;
 132 }
 133
 134 static void uhid_hid_stop(struct hid_device *hid)
 135 {
 136         struct uhid_device *uhid = hid->driver_data;
 137
 138         hid->claimed = 0;
 139         uhid_queue_event(uhid, UHID_STOP);
 140 }
 141
 142 static int uhid_hid_open(struct hid_device *hid)
 143 {
 144         struct uhid_device *uhid = hid->driver_data;
 145
 146         return uhid_queue_event(uhid, UHID_OPEN);
 147 }
 148
 149 static void uhid_hid_close(struct hid_device *hid)
 150 {
 151         struct uhid_device *uhid = hid->driver_data;
 152
 153         uhid_queue_event(uhid, UHID_CLOSE);
 154 }
 155
 156 static int uhid_hid_parse(struct hid_device *hid)
 157 {
 158         struct uhid_device *uhid = hid->driver_data;
 159
 160         return hid_parse_report(hid, uhid->rd_data, uhid->rd_size);
 161 }
 162
 163 /* must be called with report_lock held */
 164 static int __uhid_report_queue_and_wait(struct uhid_device *uhid,
 165                                         struct uhid_event *ev,
 166                                         __u32 *report_id)
 167 {
 168         unsigned long flags;
 169         int ret;
 170
 171         spin_lock_irqsave(&uhid->qlock, flags);
 172         *report_id = ++uhid->report_id;
 173         uhid->report_type = ev->type + 1;
 174         uhid->report_running = true;
 175         uhid_queue(uhid, ev);
 176         spin_unlock_irqrestore(&uhid->qlock, flags);
 177
 178         ret = wait_event_interruptible_timeout(uhid->report_wait,
 179                                 !uhid->report_running || !uhid->running,
 180                                 5 * HZ);
 181         if (!ret || !uhid->running || uhid->report_running)
 182                 ret = -EIO;
 183         else if (ret < 0)
 184                 ret = -ERESTARTSYS;
 185         else
 186                 ret = 0;
 187
 188         uhid->report_running = false;
 189
 190         return ret;
 191 }
 192
 193 static void uhid_report_wake_up(struct uhid_device *uhid, u32 id,
 194                                 const struct uhid_event *ev)
 195 {
 196         unsigned long flags;
 197
 198         spin_lock_irqsave(&uhid->qlock, flags);
 199
 200         /* id for old report; drop it silently */
 201         if (uhid->report_type != ev->type || uhid->report_id != id)
 202                 goto unlock;
 203         if (!uhid->report_running)
 204                 goto unlock;
 205
 206         memcpy(&uhid->report_buf, ev, sizeof(*ev));
 207         uhid->report_running = false;
 208         wake_up_interruptible(&uhid->report_wait);
 209
 210 unlock:
 211         spin_unlock_irqrestore(&uhid->qlock, flags);
 212 }
 213
 214 static int uhid_hid_get_report(struct hid_device *hid, unsigned char rnum,
 215                                u8 *buf, size_t count, u8 rtype)
 216 {
 217         struct uhid_device *uhid = hid->driver_data;
 218         struct uhid_get_report_reply_req *req;
 219         struct uhid_event *ev;
 220         int ret;
 221
 222         if (!uhid->running)
 223                 return -EIO;
 224
 225         ev = kzalloc(sizeof(*ev), GFP_KERNEL);
 226         if (!ev)
 227                 return -ENOMEM;
 228
 229         ev->type = UHID_GET_REPORT;
 230         ev->u.get_report.rnum = rnum;
 231         ev->u.get_report.rtype = rtype;
 232
 233         ret = mutex_lock_interruptible(&uhid->report_lock);
 234         if (ret) {
 235                 kfree(ev);
 236                 return ret;
 237         }
 238
 239         /* this _always_ takes ownership of @ev */
 240         ret = __uhid_report_queue_and_wait(uhid, ev, &ev->u.get_report.id);
 241         if (ret)
 242                 goto unlock;
 243
 244         req = &uhid->report_buf.u.get_report_reply;
 245         if (req->err) {
 246                 ret = -EIO;
 247         } else {
 248                 ret = min3(count, (size_t)req->size, (size_t)UHID_DATA_MAX);
 249                 memcpy(buf, req->data, ret);
 250         }
 251
 252 unlock:
 253         mutex_unlock(&uhid->report_lock);
 254         return ret;
 255 }
 256
 257 static int uhid_hid_set_report(struct hid_device *hid, unsigned char rnum,
 258                                const u8 *buf, size_t count, u8 rtype)
 259 {
 260         struct uhid_device *uhid = hid->driver_data;
 261         struct uhid_event *ev;
 262         int ret;
 263
 264         if (!uhid->running || count > UHID_DATA_MAX)
 265                 return -EIO;
 266
 267         ev = kzalloc(sizeof(*ev), GFP_KERNEL);
 268         if (!ev)
 269                 return -ENOMEM;
 270
 271         ev->type = UHID_SET_REPORT;
 272         ev->u.set_report.rnum = rnum;
 273         ev->u.set_report.rtype = rtype;
 274         ev->u.set_report.size = count;
 275         memcpy(ev->u.set_report.data, buf, count);
 276
 277         ret = mutex_lock_interruptible(&uhid->report_lock);
 278         if (ret) {
 279                 kfree(ev);
 280                 return ret;
 281         }
 282
 283         /* this _always_ takes ownership of @ev */
 284         ret = __uhid_report_queue_and_wait(uhid, ev, &ev->u.set_report.id);
 285         if (ret)
 286                 goto unlock;
 287
 288         if (uhid->report_buf.u.set_report_reply.err)
 289                 ret = -EIO;
 290         else
 291                 ret = count;
 292
 293 unlock:
 294         mutex_unlock(&uhid->report_lock);
 295         return ret;
 296 }
 297
 298 static int uhid_hid_raw_request(struct hid_device *hid, unsigned char reportnum,
 299                                 __u8 *buf, size_t len, unsigned char rtype,
 300                                 int reqtype)
 301 {
 302         u8 u_rtype;
 303
 304         switch (rtype) {
 305         case HID_FEATURE_REPORT:
 306                 u_rtype = UHID_FEATURE_REPORT;
 307                 break;
 308         case HID_OUTPUT_REPORT:
 309                 u_rtype = UHID_OUTPUT_REPORT;
 310                 break;
 311         case HID_INPUT_REPORT:
 312                 u_rtype = UHID_INPUT_REPORT;
 313                 break;
 314         default:
 315                 return -EINVAL;
 316         }
 317
 318         switch (reqtype) {
 319         case HID_REQ_GET_REPORT:
 320                 return uhid_hid_get_report(hid, reportnum, buf, len, u_rtype);
 321         case HID_REQ_SET_REPORT:
 322                 return uhid_hid_set_report(hid, reportnum, buf, len, u_rtype);
 323         default:
 324                 return -EIO;
 325         }
 326 }
 327
 328 static int uhid_hid_output_raw(struct hid_device *hid, __u8 *buf, size_t count,
 329                                unsigned char report_type)
 330 {
 331         struct uhid_device *uhid = hid->driver_data;
 332         __u8 rtype;
 333         unsigned long flags;
 334         struct uhid_event *ev;
 335
 336         switch (report_type) {
 337         case HID_FEATURE_REPORT:
 338                 rtype = UHID_FEATURE_REPORT;
 339                 break;
 340         case HID_OUTPUT_REPORT:
 341                 rtype = UHID_OUTPUT_REPORT;
 342                 break;
 343         default:
 344                 return -EINVAL;
 345         }
 346
 347         if (count < 1 || count > UHID_DATA_MAX)
 348                 return -EINVAL;
 349
 350         ev = kzalloc(sizeof(*ev), GFP_KERNEL);
 351         if (!ev)
 352                 return -ENOMEM;
 353
 354         ev->type = UHID_OUTPUT;
 355         ev->u.output.size = count;
 356         ev->u.output.rtype = rtype;
 357         memcpy(ev->u.output.data, buf, count);
 358
 359         spin_lock_irqsave(&uhid->qlock, flags);
 360         uhid_queue(uhid, ev);
 361         spin_unlock_irqrestore(&uhid->qlock, flags);
 362
 363         return count;
 364 }
 365
 366 static int uhid_hid_output_report(struct hid_device *hid, __u8 *buf,
 367                                   size_t count)
 368 {
 369         return uhid_hid_output_raw(hid, buf, count, HID_OUTPUT_REPORT);
 370 }
 371
 372 static struct hid_ll_driver uhid_hid_driver = {
 373         .start = uhid_hid_start,
 374         .stop = uhid_hid_stop,
 375         .open = uhid_hid_open,
 376         .close = uhid_hid_close,
 377         .parse = uhid_hid_parse,
 378         .raw_request = uhid_hid_raw_request,
 379         .output_report = uhid_hid_output_report,
 380 };
 381
 382 #ifdef CONFIG_COMPAT
 383
 384 /* Apparently we haven't stepped on these rakes enough times yet. */
 385 struct uhid_create_req_compat {
 386         __u8 name[128];
 387         __u8 phys[64];
 388         __u8 uniq[64];
 389
 390         compat_uptr_t rd_data;
 391         __u16 rd_size;
 392
 393         __u16 bus;
 394         __u32 vendor;
 395         __u32 product;
 396         __u32 version;
 397         __u32 country;
 398 } __attribute__((__packed__));
 399
 400 static int uhid_event_from_user(const char __user *buffer, size_t len,
 401                                 struct uhid_event *event)
 402 {
 403         if (in_compat_syscall()) {
 404                 u32 type;
 405
 406                 if (get_user(type, buffer))
 407                         return -EFAULT;
 408
 409                 if (type == UHID_CREATE) {
 410                         /*
 411                          * This is our messed up request with compat pointer.
 412                          * It is largish (more than 256 bytes) so we better
 413                          * allocate it from the heap.
 414                          */
 415                         struct uhid_create_req_compat *compat;
 416
 417                         compat = kzalloc(sizeof(*compat), GFP_KERNEL);
 418                         if (!compat)
 419                                 return -ENOMEM;
 420
 421                         buffer += sizeof(type);
 422                         len -= sizeof(type);
 423                         if (copy_from_user(compat, buffer,
 424                                            min(len, sizeof(*compat)))) {
 425                                 kfree(compat);
 426                                 return -EFAULT;
 427                         }
 428
 429                         /* Shuffle the data over to proper structure */
 430                         event->type = type;
 431
 432                         memcpy(event->u.create.name, compat->name,
 433                                 sizeof(compat->name));
 434                         memcpy(event->u.create.phys, compat->phys,
 435                                 sizeof(compat->phys));
 436                         memcpy(event->u.create.uniq, compat->uniq,
 437                                 sizeof(compat->uniq));
 438
 439                         event->u.create.rd_data = compat_ptr(compat->rd_data);
 440                         event->u.create.rd_size = compat->rd_size;
 441
 442                         event->u.create.bus = compat->bus;
 443                         event->u.create.vendor = compat->vendor;
 444                         event->u.create.product = compat->product;
 445                         event->u.create.version = compat->version;
 446                         event->u.create.country = compat->country;
 447
 448                         kfree(compat);
 449                         return 0;
 450                 }
 451                 /* All others can be copied directly */
 452         }
 453
 454         if (copy_from_user(event, buffer, min(len, sizeof(*event))))
 455                 return -EFAULT;
 456
 457         return 0;
 458 }
 459 #else
 460 static int uhid_event_from_user(const char __user *buffer, size_t len,
 461                                 struct uhid_event *event)
 462 {
 463         if (copy_from_user(event, buffer, min(len, sizeof(*event))))
 464                 return -EFAULT;
 465
 466         return 0;
 467 }
 468 #endif
 469
 470 static int uhid_dev_create2(struct uhid_device *uhid,
 471                             const struct uhid_event *ev)
 472 {
 473         struct hid_device *hid;
 474         size_t rd_size, len;
 475         void *rd_data;
 476         int ret;
 477
 478         if (uhid->running)
 479                 return -EALREADY;
 480
 481         rd_size = ev->u.create2.rd_size;
 482         if (rd_size <= 0 || rd_size > HID_MAX_DESCRIPTOR_SIZE)
 483                 return -EINVAL;
 484
 485         rd_data = kmemdup(ev->u.create2.rd_data, rd_size, GFP_KERNEL);
 486         if (!rd_data)
 487                 return -ENOMEM;
 488
 489         uhid->rd_size = rd_size;
 490         uhid->rd_data = rd_data;
 491
 492         hid = hid_allocate_device();
 493         if (IS_ERR(hid)) {
 494                 ret = PTR_ERR(hid);
 495                 goto err_free;
 496         }
 497
 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         nonseekable_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                 ret = uhid_dev_create(uhid, &uhid->input_buf);
 725                 break;
 726         case UHID_CREATE2:
 727                 ret = uhid_dev_create2(uhid, &uhid->input_buf);
 728                 break;
 729         case UHID_DESTROY:
 730                 ret = uhid_dev_destroy(uhid);
 731                 break;
 732         case UHID_INPUT:
 733                 ret = uhid_dev_input(uhid, &uhid->input_buf);
 734                 break;
 735         case UHID_INPUT2:
 736                 ret = uhid_dev_input2(uhid, &uhid->input_buf);
 737                 break;
 738         case UHID_GET_REPORT_REPLY:
 739                 ret = uhid_dev_get_report_reply(uhid, &uhid->input_buf);
 740                 break;
 741         case UHID_SET_REPORT_REPLY:
 742                 ret = uhid_dev_set_report_reply(uhid, &uhid->input_buf);
 743                 break;
 744         default:
 745                 ret = -EOPNOTSUPP;
 746         }
 747
 748 unlock:
 749         mutex_unlock(&uhid->devlock);
 750
 751         /* return "count" not "len" to not confuse the caller */
 752         return ret ? ret : count;
 753 }
 754
 755 static unsigned int uhid_char_poll(struct file *file, poll_table *wait)
 756 {
 757         struct uhid_device *uhid = file->private_data;
 758
 759         poll_wait(file, &uhid->waitq, wait);
 760
 761         if (uhid->head != uhid->tail)
 762                 return POLLIN | POLLRDNORM;
 763
 764         return 0;
 765 }
 766
 767 static const struct file_operations uhid_fops = {
 768         .owner          = THIS_MODULE,
 769         .open           = uhid_char_open,
 770         .release        = uhid_char_release,
 771         .read           = uhid_char_read,
 772         .write          = uhid_char_write,
 773         .poll           = uhid_char_poll,
 774         .llseek         = no_llseek,
 775 };
 776
 777 static struct miscdevice uhid_misc = {
 778         .fops           = &uhid_fops,
 779         .minor          = UHID_MINOR,
 780         .name           = UHID_NAME,
 781 };
 782 module_misc_device(uhid_misc);
 783
 784 MODULE_LICENSE("GPL");
 785 MODULE_AUTHOR("David Herrmann <dh.herrmann@gmail.com>");
 786 MODULE_DESCRIPTION("User-space I/O driver support for HID subsystem");
 787 MODULE_ALIAS_MISCDEV(UHID_MINOR);
 788 MODULE_ALIAS("devname:" UHID_NAME);