drivers/hid/hid-core.c

   1 /*
   2  *  HID support for Linux
   3  *
   4  *  Copyright (c) 1999 Andreas Gal
   5  *  Copyright (c) 2000-2005 Vojtech Pavlik <vojtech@suse.cz>
   6  *  Copyright (c) 2005 Michael Haboustak <mike-@cinci.rr.com> for Concept2, Inc
   7  *  Copyright (c) 2006 Jiri Kosina
   8  */
   9
  10 /*
  11  * This program is free software; you can redistribute it and/or modify it
  12  * under the terms of the GNU General Public License as published by the Free
  13  * Software Foundation; either version 2 of the License, or (at your option)
  14  * any later version.
  15  */
  16
  17 #include <linux/module.h>
  18 #include <linux/slab.h>
  19 #include <linux/init.h>
  20 #include <linux/kernel.h>
  21 #include <linux/sched.h>
  22 #include <linux/list.h>
  23 #include <linux/mm.h>
  24 #include <linux/smp_lock.h>
  25 #include <linux/spinlock.h>
  26 #include <asm/unaligned.h>
  27 #include <asm/byteorder.h>
  28 #include <linux/input.h>
  29 #include <linux/wait.h>
  30
  31 #undef DEBUG
  32 #undef DEBUG_DATA
  33
  34 #include <linux/hid.h>
  35 #include <linux/hiddev.h>
  36
  37 /*
  38  * Version Information
  39  */
  40
  41 #define DRIVER_VERSION "v2.6"
  42 #define DRIVER_AUTHOR "Andreas Gal, Vojtech Pavlik"
  43 #define DRIVER_DESC "USB HID core driver"
  44 #define DRIVER_LICENSE "GPL"
  45
  46 /*
  47  * Module parameters.
  48  */
  49
  50 static unsigned int hid_mousepoll_interval;
  51 module_param_named(mousepoll, hid_mousepoll_interval, uint, 0644);
  52 MODULE_PARM_DESC(mousepoll, "Polling interval of mice");
  53
  54 /*
  55  * Register a new report for a device.
  56  */
  57
  58 static struct hid_report *hid_register_report(struct hid_device *device, unsigned type, unsigned id)
  59 {
  60         struct hid_report_enum *report_enum = device->report_enum + type;
  61         struct hid_report *report;
  62
  63         if (report_enum->report_id_hash[id])
  64                 return report_enum->report_id_hash[id];
  65
  66         if (!(report = kzalloc(sizeof(struct hid_report), GFP_KERNEL)))
  67                 return NULL;
  68
  69         if (id != 0)
  70                 report_enum->numbered = 1;
  71
  72         report->id = id;
  73         report->type = type;
  74         report->size = 0;
  75         report->device = device;
  76         report_enum->report_id_hash[id] = report;
  77
  78         list_add_tail(&report->list, &report_enum->report_list);
  79
  80         return report;
  81 }
  82
  83 /*
  84  * Register a new field for this report.
  85  */
  86
  87 static struct hid_field *hid_register_field(struct hid_report *report, unsigned usages, unsigned values)
  88 {
  89         struct hid_field *field;
  90
  91         if (report->maxfield == HID_MAX_FIELDS) {
  92                 dbg("too many fields in report");
  93                 return NULL;
  94         }
  95
  96         if (!(field = kzalloc(sizeof(struct hid_field) + usages * sizeof(struct hid_usage)
  97                 + values * sizeof(unsigned), GFP_KERNEL))) return NULL;
  98
  99         field->index = report->maxfield++;
 100         report->field[field->index] = field;
 101         field->usage = (struct hid_usage *)(field + 1);
 102         field->value = (unsigned *)(field->usage + usages);
 103         field->report = report;
 104
 105         return field;
 106 }
 107
 108 /*
 109  * Open a collection. The type/usage is pushed on the stack.
 110  */
 111
 112 static int open_collection(struct hid_parser *parser, unsigned type)
 113 {
 114         struct hid_collection *collection;
 115         unsigned usage;
 116
 117         usage = parser->local.usage[0];
 118
 119         if (parser->collection_stack_ptr == HID_COLLECTION_STACK_SIZE) {
 120                 dbg("collection stack overflow");
 121                 return -1;
 122         }
 123
 124         if (parser->device->maxcollection == parser->device->collection_size) {
 125                 collection = kmalloc(sizeof(struct hid_collection) *
 126                                 parser->device->collection_size * 2, GFP_KERNEL);
 127                 if (collection == NULL) {
 128                         dbg("failed to reallocate collection array");
 129                         return -1;
 130                 }
 131                 memcpy(collection, parser->device->collection,
 132                         sizeof(struct hid_collection) *
 133                         parser->device->collection_size);
 134                 memset(collection + parser->device->collection_size, 0,
 135                         sizeof(struct hid_collection) *
 136                         parser->device->collection_size);
 137                 kfree(parser->device->collection);
 138                 parser->device->collection = collection;
 139                 parser->device->collection_size *= 2;
 140         }
 141
 142         parser->collection_stack[parser->collection_stack_ptr++] =
 143                 parser->device->maxcollection;
 144
 145         collection = parser->device->collection +
 146                 parser->device->maxcollection++;
 147         collection->type = type;
 148         collection->usage = usage;
 149         collection->level = parser->collection_stack_ptr - 1;
 150
 151         if (type == HID_COLLECTION_APPLICATION)
 152                 parser->device->maxapplication++;
 153
 154         return 0;
 155 }
 156
 157 /*
 158  * Close a collection.
 159  */
 160
 161 static int close_collection(struct hid_parser *parser)
 162 {
 163         if (!parser->collection_stack_ptr) {
 164                 dbg("collection stack underflow");
 165                 return -1;
 166         }
 167         parser->collection_stack_ptr--;
 168         return 0;
 169 }
 170
 171 /*
 172  * Climb up the stack, search for the specified collection type
 173  * and return the usage.
 174  */
 175
 176 static unsigned hid_lookup_collection(struct hid_parser *parser, unsigned type)
 177 {
 178         int n;
 179         for (n = parser->collection_stack_ptr - 1; n >= 0; n--)
 180                 if (parser->device->collection[parser->collection_stack[n]].type == type)
 181                         return parser->device->collection[parser->collection_stack[n]].usage;
 182         return 0; /* we know nothing about this usage type */
 183 }
 184
 185 /*
 186  * Add a usage to the temporary parser table.
 187  */
 188
 189 static int hid_add_usage(struct hid_parser *parser, unsigned usage)
 190 {
 191         if (parser->local.usage_index >= HID_MAX_USAGES) {
 192                 dbg("usage index exceeded");
 193                 return -1;
 194         }
 195         parser->local.usage[parser->local.usage_index] = usage;
 196         parser->local.collection_index[parser->local.usage_index] =
 197                 parser->collection_stack_ptr ?
 198                 parser->collection_stack[parser->collection_stack_ptr - 1] : 0;
 199         parser->local.usage_index++;
 200         return 0;
 201 }
 202
 203 /*
 204  * Register a new field for this report.
 205  */
 206
 207 static int hid_add_field(struct hid_parser *parser, unsigned report_type, unsigned flags)
 208 {
 209         struct hid_report *report;
 210         struct hid_field *field;
 211         int usages;
 212         unsigned offset;
 213         int i;
 214
 215         if (!(report = hid_register_report(parser->device, report_type, parser->global.report_id))) {
 216                 dbg("hid_register_report failed");
 217                 return -1;
 218         }
 219
 220         if (parser->global.logical_maximum < parser->global.logical_minimum) {
 221                 dbg("logical range invalid %d %d", parser->global.logical_minimum, parser->global.logical_maximum);
 222                 return -1;
 223         }
 224
 225         offset = report->size;
 226         report->size += parser->global.report_size * parser->global.report_count;
 227
 228         if (!parser->local.usage_index) /* Ignore padding fields */
 229                 return 0;
 230
 231         usages = max_t(int, parser->local.usage_index, parser->global.report_count);
 232
 233         if ((field = hid_register_field(report, usages, parser->global.report_count)) == NULL)
 234                 return 0;
 235
 236         field->physical = hid_lookup_collection(parser, HID_COLLECTION_PHYSICAL);
 237         field->logical = hid_lookup_collection(parser, HID_COLLECTION_LOGICAL);
 238         field->application = hid_lookup_collection(parser, HID_COLLECTION_APPLICATION);
 239
 240         for (i = 0; i < usages; i++) {
 241                 int j = i;
 242                 /* Duplicate the last usage we parsed if we have excess values */
 243                 if (i >= parser->local.usage_index)
 244                         j = parser->local.usage_index - 1;
 245                 field->usage[i].hid = parser->local.usage[j];
 246                 field->usage[i].collection_index =
 247                         parser->local.collection_index[j];
 248         }
 249
 250         field->maxusage = usages;
 251         field->flags = flags;
 252         field->report_offset = offset;
 253         field->report_type = report_type;
 254         field->report_size = parser->global.report_size;
 255         field->report_count = parser->global.report_count;
 256         field->logical_minimum = parser->global.logical_minimum;
 257         field->logical_maximum = parser->global.logical_maximum;
 258         field->physical_minimum = parser->global.physical_minimum;
 259         field->physical_maximum = parser->global.physical_maximum;
 260         field->unit_exponent = parser->global.unit_exponent;
 261         field->unit = parser->global.unit;
 262
 263         return 0;
 264 }
 265
 266 /*
 267  * Read data value from item.
 268  */
 269
 270 static u32 item_udata(struct hid_item *item)
 271 {
 272         switch (item->size) {
 273                 case 1: return item->data.u8;
 274                 case 2: return item->data.u16;
 275                 case 4: return item->data.u32;
 276         }
 277         return 0;
 278 }
 279
 280 static s32 item_sdata(struct hid_item *item)
 281 {
 282         switch (item->size) {
 283                 case 1: return item->data.s8;
 284                 case 2: return item->data.s16;
 285                 case 4: return item->data.s32;
 286         }
 287         return 0;
 288 }
 289
 290 /*
 291  * Process a global item.
 292  */
 293
 294 static int hid_parser_global(struct hid_parser *parser, struct hid_item *item)
 295 {
 296         switch (item->tag) {
 297
 298                 case HID_GLOBAL_ITEM_TAG_PUSH:
 299
 300                         if (parser->global_stack_ptr == HID_GLOBAL_STACK_SIZE) {
 301                                 dbg("global enviroment stack overflow");
 302                                 return -1;
 303                         }
 304
 305                         memcpy(parser->global_stack + parser->global_stack_ptr++,
 306                                 &parser->global, sizeof(struct hid_global));
 307                         return 0;
 308
 309                 case HID_GLOBAL_ITEM_TAG_POP:
 310
 311                         if (!parser->global_stack_ptr) {
 312                                 dbg("global enviroment stack underflow");
 313                                 return -1;
 314                         }
 315
 316                         memcpy(&parser->global, parser->global_stack + --parser->global_stack_ptr,
 317                                 sizeof(struct hid_global));
 318                         return 0;
 319
 320                 case HID_GLOBAL_ITEM_TAG_USAGE_PAGE:
 321                         parser->global.usage_page = item_udata(item);
 322                         return 0;
 323
 324                 case HID_GLOBAL_ITEM_TAG_LOGICAL_MINIMUM:
 325                         parser->global.logical_minimum = item_sdata(item);
 326                         return 0;
 327
 328                 case HID_GLOBAL_ITEM_TAG_LOGICAL_MAXIMUM:
 329                         if (parser->global.logical_minimum < 0)
 330                                 parser->global.logical_maximum = item_sdata(item);
 331                         else
 332                                 parser->global.logical_maximum = item_udata(item);
 333                         return 0;
 334
 335                 case HID_GLOBAL_ITEM_TAG_PHYSICAL_MINIMUM:
 336                         parser->global.physical_minimum = item_sdata(item);
 337                         return 0;
 338
 339                 case HID_GLOBAL_ITEM_TAG_PHYSICAL_MAXIMUM:
 340                         if (parser->global.physical_minimum < 0)
 341                                 parser->global.physical_maximum = item_sdata(item);
 342                         else
 343                                 parser->global.physical_maximum = item_udata(item);
 344                         return 0;
 345
 346                 case HID_GLOBAL_ITEM_TAG_UNIT_EXPONENT:
 347                         parser->global.unit_exponent = item_sdata(item);
 348                         return 0;
 349
 350                 case HID_GLOBAL_ITEM_TAG_UNIT:
 351                         parser->global.unit = item_udata(item);
 352                         return 0;
 353
 354                 case HID_GLOBAL_ITEM_TAG_REPORT_SIZE:
 355                         if ((parser->global.report_size = item_udata(item)) > 32) {
 356                                 dbg("invalid report_size %d", parser->global.report_size);
 357                                 return -1;
 358                         }
 359                         return 0;
 360
 361                 case HID_GLOBAL_ITEM_TAG_REPORT_COUNT:
 362                         if ((parser->global.report_count = item_udata(item)) > HID_MAX_USAGES) {
 363                                 dbg("invalid report_count %d", parser->global.report_count);
 364                                 return -1;
 365                         }
 366                         return 0;
 367
 368                 case HID_GLOBAL_ITEM_TAG_REPORT_ID:
 369                         if ((parser->global.report_id = item_udata(item)) == 0) {
 370                                 dbg("report_id 0 is invalid");
 371                                 return -1;
 372                         }
 373                         return 0;
 374
 375                 default:
 376                         dbg("unknown global tag 0x%x", item->tag);
 377                         return -1;
 378         }
 379 }
 380
 381 /*
 382  * Process a local item.
 383  */
 384
 385 static int hid_parser_local(struct hid_parser *parser, struct hid_item *item)
 386 {
 387         __u32 data;
 388         unsigned n;
 389
 390         if (item->size == 0) {
 391                 dbg("item data expected for local item");
 392                 return -1;
 393         }
 394
 395         data = item_udata(item);
 396
 397         switch (item->tag) {
 398
 399                 case HID_LOCAL_ITEM_TAG_DELIMITER:
 400
 401                         if (data) {
 402                                 /*
 403                                  * We treat items before the first delimiter
 404                                  * as global to all usage sets (branch 0).
 405                                  * In the moment we process only these global
 406                                  * items and the first delimiter set.
 407                                  */
 408                                 if (parser->local.delimiter_depth != 0) {
 409                                         dbg("nested delimiters");
 410                                         return -1;
 411                                 }
 412                                 parser->local.delimiter_depth++;
 413                                 parser->local.delimiter_branch++;
 414                         } else {
 415                                 if (parser->local.delimiter_depth < 1) {
 416                                         dbg("bogus close delimiter");
 417                                         return -1;
 418                                 }
 419                                 parser->local.delimiter_depth--;
 420                         }
 421                         return 1;
 422
 423                 case HID_LOCAL_ITEM_TAG_USAGE:
 424
 425                         if (parser->local.delimiter_branch > 1) {
 426                                 dbg("alternative usage ignored");
 427                                 return 0;
 428                         }
 429
 430                         if (item->size <= 2)
 431                                 data = (parser->global.usage_page << 16) + data;
 432
 433                         return hid_add_usage(parser, data);
 434
 435                 case HID_LOCAL_ITEM_TAG_USAGE_MINIMUM:
 436
 437                         if (parser->local.delimiter_branch > 1) {
 438                                 dbg("alternative usage ignored");
 439                                 return 0;
 440                         }
 441
 442                         if (item->size <= 2)
 443                                 data = (parser->global.usage_page << 16) + data;
 444
 445                         parser->local.usage_minimum = data;
 446                         return 0;
 447
 448                 case HID_LOCAL_ITEM_TAG_USAGE_MAXIMUM:
 449
 450                         if (parser->local.delimiter_branch > 1) {
 451                                 dbg("alternative usage ignored");
 452                                 return 0;
 453                         }
 454
 455                         if (item->size <= 2)
 456                                 data = (parser->global.usage_page << 16) + data;
 457
 458                         for (n = parser->local.usage_minimum; n <= data; n++)
 459                                 if (hid_add_usage(parser, n)) {
 460                                         dbg("hid_add_usage failed\n");
 461                                         return -1;
 462                                 }
 463                         return 0;
 464
 465                 default:
 466
 467                         dbg("unknown local item tag 0x%x", item->tag);
 468                         return 0;
 469         }
 470         return 0;
 471 }
 472
 473 /*
 474  * Process a main item.
 475  */
 476
 477 static int hid_parser_main(struct hid_parser *parser, struct hid_item *item)
 478 {
 479         __u32 data;
 480         int ret;
 481
 482         data = item_udata(item);
 483
 484         switch (item->tag) {
 485                 case HID_MAIN_ITEM_TAG_BEGIN_COLLECTION:
 486                         ret = open_collection(parser, data & 0xff);
 487                         break;
 488                 case HID_MAIN_ITEM_TAG_END_COLLECTION:
 489                         ret = close_collection(parser);
 490                         break;
 491                 case HID_MAIN_ITEM_TAG_INPUT:
 492                         ret = hid_add_field(parser, HID_INPUT_REPORT, data);
 493                         break;
 494                 case HID_MAIN_ITEM_TAG_OUTPUT:
 495                         ret = hid_add_field(parser, HID_OUTPUT_REPORT, data);
 496                         break;
 497                 case HID_MAIN_ITEM_TAG_FEATURE:
 498                         ret = hid_add_field(parser, HID_FEATURE_REPORT, data);
 499                         break;
 500                 default:
 501                         dbg("unknown main item tag 0x%x", item->tag);
 502                         ret = 0;
 503         }
 504
 505         memset(&parser->local, 0, sizeof(parser->local));       /* Reset the local parser environment */
 506
 507         return ret;
 508 }
 509
 510 /*
 511  * Process a reserved item.
 512  */
 513
 514 static int hid_parser_reserved(struct hid_parser *parser, struct hid_item *item)
 515 {
 516         dbg("reserved item type, tag 0x%x", item->tag);
 517         return 0;
 518 }
 519
 520 /*
 521  * Free a report and all registered fields. The field->usage and
 522  * field->value table's are allocated behind the field, so we need
 523  * only to free(field) itself.
 524  */
 525
 526 static void hid_free_report(struct hid_report *report)
 527 {
 528         unsigned n;
 529
 530         for (n = 0; n < report->maxfield; n++)
 531                 kfree(report->field[n]);
 532         kfree(report);
 533 }
 534
 535 /*
 536  * Free a device structure, all reports, and all fields.
 537  */
 538
 539 void hid_free_device(struct hid_device *device)
 540 {
 541         unsigned i,j;
 542
 543         for (i = 0; i < HID_REPORT_TYPES; i++) {
 544                 struct hid_report_enum *report_enum = device->report_enum + i;
 545
 546                 for (j = 0; j < 256; j++) {
 547                         struct hid_report *report = report_enum->report_id_hash[j];
 548                         if (report)
 549                                 hid_free_report(report);
 550                 }
 551         }
 552
 553         kfree(device->rdesc);
 554         kfree(device);
 555 }
 556 EXPORT_SYMBOL_GPL(hid_free_device);
 557
 558 /*
 559  * Fetch a report description item from the data stream. We support long
 560  * items, though they are not used yet.
 561  */
 562
 563 static u8 *fetch_item(__u8 *start, __u8 *end, struct hid_item *item)
 564 {
 565         u8 b;
 566
 567         if ((end - start) <= 0)
 568                 return NULL;
 569
 570         b = *start++;
 571
 572         item->type = (b >> 2) & 3;
 573         item->tag  = (b >> 4) & 15;
 574
 575         if (item->tag == HID_ITEM_TAG_LONG) {
 576
 577                 item->format = HID_ITEM_FORMAT_LONG;
 578
 579                 if ((end - start) < 2)
 580                         return NULL;
 581
 582                 item->size = *start++;
 583                 item->tag  = *start++;
 584
 585                 if ((end - start) < item->size)
 586                         return NULL;
 587
 588                 item->data.longdata = start;
 589                 start += item->size;
 590                 return start;
 591         }
 592
 593         item->format = HID_ITEM_FORMAT_SHORT;
 594         item->size = b & 3;
 595
 596         switch (item->size) {
 597
 598                 case 0:
 599                         return start;
 600
 601                 case 1:
 602                         if ((end - start) < 1)
 603                                 return NULL;
 604                         item->data.u8 = *start++;
 605                         return start;
 606
 607                 case 2:
 608                         if ((end - start) < 2)
 609                                 return NULL;
 610                         item->data.u16 = le16_to_cpu(get_unaligned((__le16*)start));
 611                         start = (__u8 *)((__le16 *)start + 1);
 612                         return start;
 613
 614                 case 3:
 615                         item->size++;
 616                         if ((end - start) < 4)
 617                                 return NULL;
 618                         item->data.u32 = le32_to_cpu(get_unaligned((__le32*)start));
 619                         start = (__u8 *)((__le32 *)start + 1);
 620                         return start;
 621         }
 622
 623         return NULL;
 624 }
 625
 626 /*
 627  * Parse a report description into a hid_device structure. Reports are
 628  * enumerated, fields are attached to these reports.
 629  */
 630
 631 struct hid_device *hid_parse_report(__u8 *start, unsigned size)
 632 {
 633         struct hid_device *device;
 634         struct hid_parser *parser;
 635         struct hid_item item;
 636         __u8 *end;
 637         unsigned i;
 638         static int (*dispatch_type[])(struct hid_parser *parser,
 639                                       struct hid_item *item) = {
 640                 hid_parser_main,
 641                 hid_parser_global,
 642                 hid_parser_local,
 643                 hid_parser_reserved
 644         };
 645
 646         if (!(device = kzalloc(sizeof(struct hid_device), GFP_KERNEL)))
 647                 return NULL;
 648
 649         if (!(device->collection = kzalloc(sizeof(struct hid_collection) *
 650                                    HID_DEFAULT_NUM_COLLECTIONS, GFP_KERNEL))) {
 651                 kfree(device);
 652                 return NULL;
 653         }
 654         device->collection_size = HID_DEFAULT_NUM_COLLECTIONS;
 655
 656         for (i = 0; i < HID_REPORT_TYPES; i++)
 657                 INIT_LIST_HEAD(&device->report_enum[i].report_list);
 658
 659         if (!(device->rdesc = (__u8 *)kmalloc(size, GFP_KERNEL))) {
 660                 kfree(device->collection);
 661                 kfree(device);
 662                 return NULL;
 663         }
 664         memcpy(device->rdesc, start, size);
 665         device->rsize = size;
 666
 667         if (!(parser = kzalloc(sizeof(struct hid_parser), GFP_KERNEL))) {
 668                 kfree(device->rdesc);
 669                 kfree(device->collection);
 670                 kfree(device);
 671                 return NULL;
 672         }
 673         parser->device = device;
 674
 675         end = start + size;
 676         while ((start = fetch_item(start, end, &item)) != NULL) {
 677
 678                 if (item.format != HID_ITEM_FORMAT_SHORT) {
 679                         dbg("unexpected long global item");
 680                         kfree(device->collection);
 681                         hid_free_device(device);
 682                         kfree(parser);
 683                         return NULL;
 684                 }
 685
 686                 if (dispatch_type[item.type](parser, &item)) {
 687                         dbg("item %u %u %u %u parsing failed\n",
 688                                 item.format, (unsigned)item.size, (unsigned)item.type, (unsigned)item.tag);
 689                         kfree(device->collection);
 690                         hid_free_device(device);
 691                         kfree(parser);
 692                         return NULL;
 693                 }
 694
 695                 if (start == end) {
 696                         if (parser->collection_stack_ptr) {
 697                                 dbg("unbalanced collection at end of report description");
 698                                 kfree(device->collection);
 699                                 hid_free_device(device);
 700                                 kfree(parser);
 701                                 return NULL;
 702                         }
 703                         if (parser->local.delimiter_depth) {
 704                                 dbg("unbalanced delimiter at end of report description");
 705                                 kfree(device->collection);
 706                                 hid_free_device(device);
 707                                 kfree(parser);
 708                                 return NULL;
 709                         }
 710                         kfree(parser);
 711                         return device;
 712                 }
 713         }
 714
 715         dbg("item fetching failed at offset %d\n", (int)(end - start));
 716         kfree(device->collection);
 717         hid_free_device(device);
 718         kfree(parser);
 719         return NULL;
 720 }
 721 EXPORT_SYMBOL_GPL(hid_parse_report);
 722
 723 /*
 724  * Convert a signed n-bit integer to signed 32-bit integer. Common
 725  * cases are done through the compiler, the screwed things has to be
 726  * done by hand.
 727  */
 728
 729 static s32 snto32(__u32 value, unsigned n)
 730 {
 731         switch (n) {
 732                 case 8:  return ((__s8)value);
 733                 case 16: return ((__s16)value);
 734                 case 32: return ((__s32)value);
 735         }
 736         return value & (1 << (n - 1)) ? value | (-1 << n) : value;
 737 }
 738
 739 /*
 740  * Convert a signed 32-bit integer to a signed n-bit integer.
 741  */
 742
 743 static u32 s32ton(__s32 value, unsigned n)
 744 {
 745         s32 a = value >> (n - 1);
 746         if (a && a != -1)
 747                 return value < 0 ? 1 << (n - 1) : (1 << (n - 1)) - 1;
 748         return value & ((1 << n) - 1);
 749 }
 750
 751 /*
 752  * Extract/implement a data field from/to a little endian report (bit array).
 753  *
 754  * Code sort-of follows HID spec:
 755  *     http://www.usb.org/developers/devclass_docs/HID1_11.pdf
 756  *
 757  * While the USB HID spec allows unlimited length bit fields in "report
 758  * descriptors", most devices never use more than 16 bits.
 759  * One model of UPS is claimed to report "LINEV" as a 32-bit field.
 760  * Search linux-kernel and linux-usb-devel archives for "hid-core extract".
 761  */
 762
 763 static __inline__ __u32 extract(__u8 *report, unsigned offset, unsigned n)
 764 {
 765         u64 x;
 766
 767         WARN_ON(n > 32);
 768
 769         report += offset >> 3;  /* adjust byte index */
 770         offset &= 7;            /* now only need bit offset into one byte */
 771         x = get_unaligned((u64 *) report);
 772         x = le64_to_cpu(x);
 773         x = (x >> offset) & ((1ULL << n) - 1);  /* extract bit field */
 774         return (u32) x;
 775 }
 776
 777 /*
 778  * "implement" : set bits in a little endian bit stream.
 779  * Same concepts as "extract" (see comments above).
 780  * The data mangled in the bit stream remains in little endian
 781  * order the whole time. It make more sense to talk about
 782  * endianness of register values by considering a register
 783  * a "cached" copy of the little endiad bit stream.
 784  */
 785 static __inline__ void implement(__u8 *report, unsigned offset, unsigned n, __u32 value)
 786 {
 787         u64 x;
 788         u64 m = (1ULL << n) - 1;
 789
 790         WARN_ON(n > 32);
 791
 792         WARN_ON(value > m);
 793         value &= m;
 794
 795         report += offset >> 3;
 796         offset &= 7;
 797
 798         x = get_unaligned((u64 *)report);
 799         x &= cpu_to_le64(~(m << offset));
 800         x |= cpu_to_le64(((u64) value) << offset);
 801         put_unaligned(x, (u64 *) report);
 802 }
 803
 804 /*
 805  * Search an array for a value.
 806  */
 807
 808 static __inline__ int search(__s32 *array, __s32 value, unsigned n)
 809 {
 810         while (n--) {
 811                 if (*array++ == value)
 812                         return 0;
 813         }
 814         return -1;
 815 }
 816
 817 static void hid_process_event(struct hid_device *hid, struct hid_field *field, struct hid_usage *usage, __s32 value, int interrupt)
 818 {
 819         hid_dump_input(usage, value);
 820         if (hid->claimed & HID_CLAIMED_INPUT)
 821                 hidinput_hid_event(hid, field, usage, value);
 822         if (hid->claimed & HID_CLAIMED_HIDDEV && interrupt)
 823                 hiddev_hid_event(hid, field, usage, value);
 824 }
 825
 826 /*
 827  * Analyse a received field, and fetch the data from it. The field
 828  * content is stored for next report processing (we do differential
 829  * reporting to the layer).
 830  */
 831
 832 void hid_input_field(struct hid_device *hid, struct hid_field *field, __u8 *data, int interrupt)
 833 {
 834         unsigned n;
 835         unsigned count = field->report_count;
 836         unsigned offset = field->report_offset;
 837         unsigned size = field->report_size;
 838         __s32 min = field->logical_minimum;
 839         __s32 max = field->logical_maximum;
 840         __s32 *value;
 841
 842         if (!(value = kmalloc(sizeof(__s32) * count, GFP_ATOMIC)))
 843                 return;
 844
 845         for (n = 0; n < count; n++) {
 846
 847                         value[n] = min < 0 ? snto32(extract(data, offset + n * size, size), size) :
 848                                                     extract(data, offset + n * size, size);
 849
 850                         if (!(field->flags & HID_MAIN_ITEM_VARIABLE) /* Ignore report if ErrorRollOver */
 851                             && value[n] >= min && value[n] <= max
 852                             && field->usage[value[n] - min].hid == HID_UP_KEYBOARD + 1)
 853                                 goto exit;
 854         }
 855
 856         for (n = 0; n < count; n++) {
 857
 858                 if (HID_MAIN_ITEM_VARIABLE & field->flags) {
 859                         hid_process_event(hid, field, &field->usage[n], value[n], interrupt);
 860                         continue;
 861                 }
 862
 863                 if (field->value[n] >= min && field->value[n] <= max
 864                         && field->usage[field->value[n] - min].hid
 865                         && search(value, field->value[n], count))
 866                                 hid_process_event(hid, field, &field->usage[field->value[n] - min], 0, interrupt);
 867
 868                 if (value[n] >= min && value[n] <= max
 869                         && field->usage[value[n] - min].hid
 870                         && search(field->value, value[n], count))
 871                                 hid_process_event(hid, field, &field->usage[value[n] - min], 1, interrupt);
 872         }
 873
 874         memcpy(field->value, value, count * sizeof(__s32));
 875 exit:
 876         kfree(value);
 877 }
 878 EXPORT_SYMBOL_GPL(hid_input_field);
 879
 880 /*
 881  * Output the field into the report.
 882  */
 883
 884 static void hid_output_field(struct hid_field *field, __u8 *data)
 885 {
 886         unsigned count = field->report_count;
 887         unsigned offset = field->report_offset;
 888         unsigned size = field->report_size;
 889         unsigned n;
 890
 891         for (n = 0; n < count; n++) {
 892                 if (field->logical_minimum < 0) /* signed values */
 893                         implement(data, offset + n * size, size, s32ton(field->value[n], size));
 894                 else                            /* unsigned values */
 895                         implement(data, offset + n * size, size, field->value[n]);
 896         }
 897 }
 898
 899 /*
 900  * Create a report.
 901  */
 902
 903 void hid_output_report(struct hid_report *report, __u8 *data)
 904 {
 905         unsigned n;
 906
 907         if (report->id > 0)
 908                 *data++ = report->id;
 909
 910         for (n = 0; n < report->maxfield; n++)
 911                 hid_output_field(report->field[n], data);
 912 }
 913 EXPORT_SYMBOL_GPL(hid_output_report);
 914
 915 /*
 916  * Set a field value. The report this field belongs to has to be
 917  * created and transferred to the device, to set this value in the
 918  * device.
 919  */
 920
 921 int hid_set_field(struct hid_field *field, unsigned offset, __s32 value)
 922 {
 923         unsigned size = field->report_size;
 924
 925         hid_dump_input(field->usage + offset, value);
 926
 927         if (offset >= field->report_count) {
 928                 dbg("offset (%d) exceeds report_count (%d)", offset, field->report_count);
 929                 hid_dump_field(field, 8);
 930                 return -1;
 931         }
 932         if (field->logical_minimum < 0) {
 933                 if (value != snto32(s32ton(value, size), size)) {
 934                         dbg("value %d is out of range", value);
 935                         return -1;
 936                 }
 937         }
 938         field->value[offset] = value;
 939         return 0;
 940 }
 941 EXPORT_SYMBOL_GPL(hid_set_field);
 942