sys/dev/usb/usb_hid.c

   1 /*      $NetBSD: hid.c,v 1.17 2001/11/13 06:24:53 lukem Exp $   */
   2
   3
   4 #include <sys/cdefs.h>
   5 __FBSDID("$FreeBSD$");
   6 /*-
   7  * Copyright (c) 1998 The NetBSD Foundation, Inc.
   8  * All rights reserved.
   9  *
  10  * This code is derived from software contributed to The NetBSD Foundation
  11  * by Lennart Augustsson (lennart@augustsson.net) at
  12  * Carlstedt Research & Technology.
  13  *
  14  * Redistribution and use in source and binary forms, with or without
  15  * modification, are permitted provided that the following conditions
  16  * are met:
  17  * 1. Redistributions of source code must retain the above copyright
  18  *    notice, this list of conditions and the following disclaimer.
  19  * 2. Redistributions in binary form must reproduce the above copyright
  20  *    notice, this list of conditions and the following disclaimer in the
  21  *    documentation and/or other materials provided with the distribution.
  22  * 3. All advertising materials mentioning features or use of this software
  23  *    must display the following acknowledgement:
  24  *        This product includes software developed by the NetBSD
  25  *        Foundation, Inc. and its contributors.
  26  * 4. Neither the name of The NetBSD Foundation nor the names of its
  27  *    contributors may be used to endorse or promote products derived
  28  *    from this software without specific prior written permission.
  29  *
  30  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  31  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  32  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  33  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  34  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  35  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  36  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  37  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  38  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  39  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  40  * POSSIBILITY OF SUCH DAMAGE.
  41  */
  42
  43 #include <dev/usb/usb.h>
  44 #include <dev/usb/usb_mfunc.h>
  45 #include <dev/usb/usb_error.h>
  46 #include <dev/usb/usb_defs.h>
  47 #include <dev/usb/usbhid.h>
  48
  49 #define USB_DEBUG_VAR usb2_debug
  50
  51 #include <dev/usb/usb_core.h>
  52 #include <dev/usb/usb_debug.h>
  53 #include <dev/usb/usb_parse.h>
  54 #include <dev/usb/usb_process.h>
  55 #include <dev/usb/usb_device.h>
  56 #include <dev/usb/usb_request.h>
  57 #include <dev/usb/usb_hid.h>
  58
  59 static void hid_clear_local(struct hid_item *);
  60 static uint8_t hid_get_byte(struct hid_data *s, const uint16_t wSize);
  61
  62 #define MAXUSAGE 64
  63 #define MAXPUSH 4
  64 struct hid_data {
  65         const uint8_t *start;
  66         const uint8_t *end;
  67         const uint8_t *p;
  68         struct hid_item cur[MAXPUSH];
  69         int32_t usages_min[MAXUSAGE];
  70         int32_t usages_max[MAXUSAGE];
  71         int32_t usage_last;     /* last seen usage */
  72         uint32_t loc_size;      /* last seen size */
  73         uint32_t loc_count;     /* last seen count */
  74         uint8_t kindset;        /* we have 5 kinds so 8 bits are enough */
  75         uint8_t pushlevel;      /* current pushlevel */
  76         uint8_t ncount;         /* end usage item count */
  77         uint8_t icount;         /* current usage item count */
  78         uint8_t nusage;         /* end "usages_min/max" index */
  79         uint8_t iusage;         /* current "usages_min/max" index */
  80         uint8_t ousage;         /* current "usages_min/max" offset */
  81         uint8_t susage;         /* usage set flags */
  82 };
  83
  84 /*------------------------------------------------------------------------*
  85  *      hid_clear_local
  86  *------------------------------------------------------------------------*/
  87 static void
  88 hid_clear_local(struct hid_item *c)
  89 {
  90
  91         c->loc.count = 0;
  92         c->loc.size = 0;
  93         c->usage = 0;
  94         c->usage_minimum = 0;
  95         c->usage_maximum = 0;
  96         c->designator_index = 0;
  97         c->designator_minimum = 0;
  98         c->designator_maximum = 0;
  99         c->string_index = 0;
 100         c->string_minimum = 0;
 101         c->string_maximum = 0;
 102         c->set_delimiter = 0;
 103 }
 104
 105 /*------------------------------------------------------------------------*
 106  *      hid_start_parse
 107  *------------------------------------------------------------------------*/
 108 struct hid_data *
 109 hid_start_parse(const void *d, int len, int kindset)
 110 {
 111         struct hid_data *s;
 112
 113         if ((kindset-1) & kindset) {
 114                 DPRINTFN(0, "Only one bit can be "
 115                     "set in the kindset\n");
 116                 return (NULL);
 117         }
 118
 119         s = malloc(sizeof *s, M_TEMP, M_WAITOK | M_ZERO);
 120         s->start = s->p = d;
 121         s->end = ((const uint8_t *)d) + len;
 122         s->kindset = kindset;
 123         return (s);
 124 }
 125
 126 /*------------------------------------------------------------------------*
 127  *      hid_end_parse
 128  *------------------------------------------------------------------------*/
 129 void
 130 hid_end_parse(struct hid_data *s)
 131 {
 132         if (s == NULL)
 133                 return;
 134
 135         free(s, M_TEMP);
 136 }
 137
 138 /*------------------------------------------------------------------------*
 139  *      get byte from HID descriptor
 140  *------------------------------------------------------------------------*/
 141 static uint8_t
 142 hid_get_byte(struct hid_data *s, const uint16_t wSize)
 143 {
 144         const uint8_t *ptr;
 145         uint8_t retval;
 146
 147         ptr = s->p;
 148
 149         /* check if end is reached */
 150         if (ptr == s->end)
 151                 return (0);
 152
 153         /* read out a byte */
 154         retval = *ptr;
 155
 156         /* check if data pointer can be advanced by "wSize" bytes */
 157         if ((s->end - ptr) < wSize)
 158                 ptr = s->end;
 159         else
 160                 ptr += wSize;
 161
 162         /* update pointer */
 163         s->p = ptr;
 164
 165         return (retval);
 166 }
 167
 168 /*------------------------------------------------------------------------*
 169  *      hid_get_item
 170  *------------------------------------------------------------------------*/
 171 int
 172 hid_get_item(struct hid_data *s, struct hid_item *h)
 173 {
 174         struct hid_item *c;
 175         unsigned int bTag, bType, bSize;
 176         uint32_t oldpos;
 177         int32_t mask;
 178         int32_t dval;
 179
 180         if (s == NULL)
 181                 return (0);
 182
 183         c = &s->cur[s->pushlevel];
 184
 185  top:
 186         /* check if there is an array of items */
 187         if (s->icount < s->ncount) {
 188                 /* get current usage */
 189                 if (s->iusage < s->nusage) {
 190                         dval = s->usages_min[s->iusage] + s->ousage;
 191                         c->usage = dval;
 192                         s->usage_last = dval;
 193                         if (dval == s->usages_max[s->iusage]) {
 194                                 s->iusage ++;
 195                                 s->ousage = 0;
 196                         } else {
 197                                 s->ousage ++;
 198                         }
 199                 } else {
 200                         DPRINTFN(1, "Using last usage\n");
 201                         dval = s->usage_last;
 202                 }
 203                 s->icount ++;
 204                 /*
 205                  * Only copy HID item, increment position and return
 206                  * if correct kindset!
 207                  */
 208                 if (s->kindset & (1 << c->kind)) {
 209                         *h = *c;
 210                         DPRINTFN(1, "%u,%u,%u\n", h->loc.pos,
 211                             h->loc.size, h->loc.count);
 212                         c->loc.pos += c->loc.size * c->loc.count;
 213                         return (1);
 214                 }
 215         }
 216
 217         /* reset state variables */
 218         s->icount = 0;
 219         s->ncount = 0;
 220         s->iusage = 0;
 221         s->nusage = 0;
 222         s->susage = 0;
 223         s->ousage = 0;
 224         hid_clear_local(c);
 225
 226         /* get next item */
 227         while (s->p != s->end) {
 228
 229                 bSize = hid_get_byte(s, 1);
 230                 if (bSize == 0xfe) {
 231                         /* long item */
 232                         bSize = hid_get_byte(s, 1);
 233                         bSize |= hid_get_byte(s, 1) << 8;
 234                         bTag = hid_get_byte(s, 1);
 235                         bType = 0xff;   /* XXX what should it be */
 236                 } else {
 237                         /* short item */
 238                         bTag = bSize >> 4;
 239                         bType = (bSize >> 2) & 3;
 240                         bSize &= 3;
 241                         if (bSize == 3)
 242                                 bSize = 4;
 243                 }
 244                 switch (bSize) {
 245                 case 0:
 246                         dval = 0;
 247                         mask = 0;
 248                         break;
 249                 case 1:
 250                         dval = (int8_t)hid_get_byte(s, 1);
 251                         mask = 0xFF;
 252                         break;
 253                 case 2:
 254                         dval = hid_get_byte(s, 1);
 255                         dval |= hid_get_byte(s, 1) << 8;
 256                         dval = (int16_t)dval;
 257                         mask = 0xFFFF;
 258                         break;
 259                 case 4:
 260                         dval = hid_get_byte(s, 1);
 261                         dval |= hid_get_byte(s, 1) << 8;
 262                         dval |= hid_get_byte(s, 1) << 16;
 263                         dval |= hid_get_byte(s, 1) << 24;
 264                         mask = 0xFFFFFFFF;
 265                         break;
 266                 default:
 267                         dval = hid_get_byte(s, bSize);
 268                         DPRINTFN(0, "bad length %u (data=0x%02x)\n",
 269                             bSize, dval);
 270                         continue;
 271                 }
 272
 273                 switch (bType) {
 274                 case 0:         /* Main */
 275                         switch (bTag) {
 276                         case 8: /* Input */
 277                                 c->kind = hid_input;
 278                                 c->flags = dval;
 279                 ret:
 280                                 c->loc.count = s->loc_count;
 281                                 c->loc.size = s->loc_size;
 282
 283                                 if (c->flags & HIO_VARIABLE) {
 284                                         /* range check usage count */
 285                                         if (c->loc.count > 255) {
 286                                                 DPRINTFN(0, "Number of "
 287                                                     "items truncated to 255\n");
 288                                                 s->ncount = 255;
 289                                         } else
 290                                                 s->ncount = c->loc.count;
 291
 292                                         /*
 293                                          * The "top" loop will return
 294                                          * one and one item:
 295                                          */
 296                                         c->loc.count = 1;
 297                                 } else {
 298                                         s->ncount = 1;
 299                                 }
 300                                 /* set default usage */
 301                                 /* use the undefined HID PAGE */
 302                                 s->usage_last = 0;
 303                                 goto top;
 304
 305                         case 9: /* Output */
 306                                 c->kind = hid_output;
 307                                 c->flags = dval;
 308                                 goto ret;
 309                         case 10:        /* Collection */
 310                                 c->kind = hid_collection;
 311                                 c->collection = dval;
 312                                 c->collevel++;
 313                                 *h = *c;
 314                                 return (1);
 315                         case 11:        /* Feature */
 316                                 c->kind = hid_feature;
 317                                 c->flags = dval;
 318                                 goto ret;
 319                         case 12:        /* End collection */
 320                                 c->kind = hid_endcollection;
 321                                 if (c->collevel == 0) {
 322                                         DPRINTFN(0, "invalid end collection\n");
 323                                         return (0);
 324                                 }
 325                                 c->collevel--;
 326                                 *h = *c;
 327                                 return (1);
 328                         default:
 329                                 DPRINTFN(0, "Main bTag=%d\n", bTag);
 330                                 break;
 331                         }
 332                         break;
 333                 case 1:         /* Global */
 334                         switch (bTag) {
 335                         case 0:
 336                                 c->_usage_page = dval << 16;
 337                                 break;
 338                         case 1:
 339                                 c->logical_minimum = dval;
 340                                 break;
 341                         case 2:
 342                                 c->logical_maximum = dval;
 343                                 break;
 344                         case 3:
 345                                 c->physical_minimum = dval;
 346                                 break;
 347                         case 4:
 348                                 c->physical_maximum = dval;
 349                                 break;
 350                         case 5:
 351                                 c->unit_exponent = dval;
 352                                 break;
 353                         case 6:
 354                                 c->unit = dval;
 355                                 break;
 356                         case 7:
 357                                 /* mask because value is unsigned */
 358                                 s->loc_size = dval & mask;
 359                                 break;
 360                         case 8:
 361                                 c->report_ID = dval;
 362                                 /* new report - reset position */
 363                                 c->loc.pos = 0;
 364                                 break;
 365                         case 9:
 366                                 /* mask because value is unsigned */
 367                                 s->loc_count = dval & mask;
 368                                 break;
 369                         case 10:        /* Push */
 370                                 s->pushlevel ++;
 371                                 if (s->pushlevel < MAXPUSH) {
 372                                         s->cur[s->pushlevel] = *c;
 373                                         /* store size and count */
 374                                         c->loc.size = s->loc_size;
 375                                         c->loc.count = s->loc_count;
 376                                         /* update current item pointer */
 377                                         c = &s->cur[s->pushlevel];
 378                                 } else {
 379                                         DPRINTFN(0, "Cannot push "
 380                                             "item @ %d!\n", s->pushlevel);
 381                                 }
 382                                 break;
 383                         case 11:        /* Pop */
 384                                 s->pushlevel --;
 385                                 if (s->pushlevel < MAXPUSH) {
 386                                         /* preserve position */
 387                                         oldpos = c->loc.pos;
 388                                         c = &s->cur[s->pushlevel];
 389                                         /* restore size and count */
 390                                         s->loc_size = c->loc.size;
 391                                         s->loc_count = c->loc.count;
 392                                         /* set default item location */
 393                                         c->loc.pos = oldpos;
 394                                         c->loc.size = 0;
 395                                         c->loc.count = 0;
 396                                 } else {
 397                                         DPRINTFN(0, "Cannot pop "
 398                                             "item @ %d!\n", s->pushlevel);
 399                                 }
 400                                 break;
 401                         default:
 402                                 DPRINTFN(0, "Global bTag=%d\n", bTag);
 403                                 break;
 404                         }
 405                         break;
 406                 case 2:         /* Local */
 407                         switch (bTag) {
 408                         case 0:
 409                                 if (bSize != 4)
 410                                         dval = (dval & mask) | c->_usage_page;
 411
 412                                 if (s->nusage < MAXUSAGE) {
 413                                         s->usages_min[s->nusage] = dval;
 414                                         s->usages_max[s->nusage] = dval;
 415                                         s->nusage ++;
 416                                 } else {
 417                                         DPRINTFN(0, "max usage reached!\n");
 418                                 }
 419
 420                                 /* clear any pending usage sets */
 421                                 s->susage = 0;
 422                                 break;
 423                         case 1:
 424                                 s->susage |= 1;
 425
 426                                 if (bSize != 4)
 427                                         dval = (dval & mask) | c->_usage_page;
 428                                 c->usage_minimum = dval;
 429
 430                                 goto check_set;
 431                         case 2:
 432                                 s->susage |= 2;
 433
 434                                 if (bSize != 4)
 435                                         dval = (dval & mask) | c->_usage_page;
 436                                 c->usage_maximum = dval;
 437
 438                         check_set:
 439                                 if (s->susage != 3)
 440                                         break;
 441
 442                                 /* sanity check */
 443                                 if ((s->nusage < MAXUSAGE) &&
 444                                     (c->usage_minimum < c->usage_maximum)) {
 445                                         /* add usage range */
 446                                         s->usages_min[s->nusage] =
 447                                             c->usage_minimum;
 448                                         s->usages_max[s->nusage] =
 449                                             c->usage_maximum;
 450                                         s->nusage ++;
 451                                 } else {
 452                                         DPRINTFN(0, "Usage set dropped!\n");
 453                                 }
 454                                 s->susage = 0;
 455                                 break;
 456                         case 3:
 457                                 c->designator_index = dval;
 458                                 break;
 459                         case 4:
 460                                 c->designator_minimum = dval;
 461                                 break;
 462                         case 5:
 463                                 c->designator_maximum = dval;
 464                                 break;
 465                         case 7:
 466                                 c->string_index = dval;
 467                                 break;
 468                         case 8:
 469                                 c->string_minimum = dval;
 470                                 break;
 471                         case 9:
 472                                 c->string_maximum = dval;
 473                                 break;
 474                         case 10:
 475                                 c->set_delimiter = dval;
 476                                 break;
 477                         default:
 478                                 DPRINTFN(0, "Local bTag=%d\n", bTag);
 479                                 break;
 480                         }
 481                         break;
 482                 default:
 483                         DPRINTFN(0, "default bType=%d\n", bType);
 484                         break;
 485                 }
 486         }
 487         return (0);
 488 }
 489
 490 /*------------------------------------------------------------------------*
 491  *      hid_report_size
 492  *------------------------------------------------------------------------*/
 493 int
 494 hid_report_size(const void *buf, int len, enum hid_kind k, uint8_t *id)
 495 {
 496         struct hid_data *d;
 497         struct hid_item h;
 498         uint32_t temp;
 499         uint32_t hpos;
 500         uint32_t lpos;
 501         uint8_t any_id;
 502
 503         any_id = 0;
 504         hpos = 0;
 505         lpos = 0xFFFFFFFF;
 506
 507         for (d = hid_start_parse(buf, len, 1 << k); hid_get_item(d, &h);) {
 508                 if (h.kind == k) {
 509                         /* check for ID-byte presense */
 510                         if ((h.report_ID != 0) && !any_id) {
 511                                 if (id != NULL)
 512                                         *id = h.report_ID;
 513                                 any_id = 1;
 514                         }
 515                         /* compute minimum */
 516                         if (lpos > h.loc.pos)
 517                                 lpos = h.loc.pos;
 518                         /* compute end position */
 519                         temp = h.loc.pos + (h.loc.size * h.loc.count);
 520                         /* compute maximum */
 521                         if (hpos < temp)
 522                                 hpos = temp;
 523                 }
 524         }
 525         hid_end_parse(d);
 526
 527         /* safety check - can happen in case of currupt descriptors */
 528         if (lpos > hpos)
 529                 temp = 0;
 530         else
 531                 temp = hpos - lpos;
 532
 533         /* check for ID byte */
 534         if (any_id)
 535                 temp += 8;
 536         else if (id != NULL)
 537                 *id = 0;
 538
 539         /* return length in bytes rounded up */
 540         return ((temp + 7) / 8);
 541 }
 542
 543 /*------------------------------------------------------------------------*
 544  *      hid_locate
 545  *------------------------------------------------------------------------*/
 546 int
 547 hid_locate(const void *desc, int size, uint32_t u, enum hid_kind k,
 548     struct hid_location *loc, uint32_t *flags, uint8_t *id)
 549 {
 550         struct hid_data *d;
 551         struct hid_item h;
 552
 553         for (d = hid_start_parse(desc, size, 1 << k); hid_get_item(d, &h);) {
 554                 if (h.kind == k && !(h.flags & HIO_CONST) && h.usage == u) {
 555                         if (loc != NULL)
 556                                 *loc = h.loc;
 557                         if (flags != NULL)
 558                                 *flags = h.flags;
 559                         if (id != NULL)
 560                                 *id = h.report_ID;
 561                         hid_end_parse(d);
 562                         return (1);
 563                 }
 564         }
 565         if (loc != NULL)
 566                 loc->size = 0;
 567         if (flags != NULL)
 568                 *flags = 0;
 569         if (id != NULL)
 570                 *id = 0;
 571         hid_end_parse(d);
 572         return (0);
 573 }
 574
 575 /*------------------------------------------------------------------------*
 576  *      hid_get_data
 577  *------------------------------------------------------------------------*/
 578 uint32_t
 579 hid_get_data(const uint8_t *buf, uint32_t len, struct hid_location *loc)
 580 {
 581         uint32_t hpos = loc->pos;
 582         uint32_t hsize = loc->size;
 583         uint32_t data;
 584         uint32_t rpos;
 585         uint8_t n;
 586
 587         DPRINTFN(11, "hid_get_data: loc %d/%d\n", hpos, hsize);
 588
 589         /* Range check and limit */
 590         if (hsize == 0)
 591                 return (0);
 592         if (hsize > 32)
 593                 hsize = 32;
 594
 595         /* Get data in a safe way */
 596         data = 0;
 597         rpos = (hpos / 8);
 598         n = (hsize + 7) / 8;
 599         rpos += n;
 600         while (n--) {
 601                 rpos--;
 602                 if (rpos < len)
 603                         data |= buf[rpos] << (8 * n);
 604         }
 605
 606         /* Correctly shift down data */
 607         data = (data >> (hpos % 8));
 608
 609         /* Mask and sign extend in one */
 610         n = 32 - hsize;
 611         data = ((int32_t)data << n) >> n;
 612
 613         DPRINTFN(11, "hid_get_data: loc %d/%d = %lu\n",
 614             loc->pos, loc->size, (long)data);
 615         return (data);
 616 }
 617
 618 /*------------------------------------------------------------------------*
 619  *      hid_is_collection
 620  *------------------------------------------------------------------------*/
 621 int
 622 hid_is_collection(const void *desc, int size, uint32_t usage)
 623 {
 624         struct hid_data *hd;
 625         struct hid_item hi;
 626         int err;
 627
 628         hd = hid_start_parse(desc, size, hid_input);
 629         if (hd == NULL)
 630                 return (0);
 631
 632         err = hid_get_item(hd, &hi) &&
 633             hi.kind == hid_collection &&
 634             hi.usage == usage;
 635         hid_end_parse(hd);
 636         return (err);
 637 }
 638
 639 /*------------------------------------------------------------------------*
 640  *      hid_get_descriptor_from_usb
 641  *
 642  * This function will search for a HID descriptor between two USB
 643  * interface descriptors.
 644  *
 645  * Return values:
 646  * NULL: No more HID descriptors.
 647  * Else: Pointer to HID descriptor.
 648  *------------------------------------------------------------------------*/
 649 struct usb2_hid_descriptor *
 650 hid_get_descriptor_from_usb(struct usb2_config_descriptor *cd,
 651     struct usb2_interface_descriptor *id)
 652 {
 653         struct usb2_descriptor *desc = (void *)id;
 654
 655         if (desc == NULL) {
 656                 return (NULL);
 657         }
 658         while ((desc = usb2_desc_foreach(cd, desc))) {
 659                 if ((desc->bDescriptorType == UDESC_HID) &&
 660                     (desc->bLength >= USB_HID_DESCRIPTOR_SIZE(0))) {
 661                         return (void *)desc;
 662                 }
 663                 if (desc->bDescriptorType == UDESC_INTERFACE) {
 664                         break;
 665                 }
 666         }
 667         return (NULL);
 668 }
 669
 670 /*------------------------------------------------------------------------*
 671  *      usb2_req_get_hid_desc
 672  *
 673  * This function will read out an USB report descriptor from the USB
 674  * device.
 675  *
 676  * Return values:
 677  * NULL: Failure.
 678  * Else: Success. The pointer should eventually be passed to free().
 679  *------------------------------------------------------------------------*/
 680 usb2_error_t
 681 usb2_req_get_hid_desc(struct usb2_device *udev, struct mtx *mtx,
 682     void **descp, uint16_t *sizep,
 683     usb2_malloc_type mem, uint8_t iface_index)
 684 {
 685         struct usb2_interface *iface = usb2_get_iface(udev, iface_index);
 686         struct usb2_hid_descriptor *hid;
 687         usb2_error_t err;
 688
 689         if ((iface == NULL) || (iface->idesc == NULL)) {
 690                 return (USB_ERR_INVAL);
 691         }
 692         hid = hid_get_descriptor_from_usb
 693             (usb2_get_config_descriptor(udev), iface->idesc);
 694
 695         if (hid == NULL) {
 696                 return (USB_ERR_IOERROR);
 697         }
 698         *sizep = UGETW(hid->descrs[0].wDescriptorLength);
 699         if (*sizep == 0) {
 700                 return (USB_ERR_IOERROR);
 701         }
 702         if (mtx)
 703                 mtx_unlock(mtx);
 704
 705         *descp = malloc(*sizep, mem, M_ZERO | M_WAITOK);
 706
 707         if (mtx)
 708                 mtx_lock(mtx);
 709
 710         if (*descp == NULL) {
 711                 return (USB_ERR_NOMEM);
 712         }
 713         err = usb2_req_get_report_descriptor
 714             (udev, mtx, *descp, *sizep, iface_index);
 715
 716         if (err) {
 717                 free(*descp, mem);
 718                 *descp = NULL;
 719                 return (err);
 720         }
 721         return (USB_ERR_NORMAL_COMPLETION);
 722 }