drivers/iio/test/iio-test-rescale.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Kunit tests for IIO rescale conversions
   4  *
   5  * Copyright (c) 2021 Liam Beguin <liambeguin@gmail.com>
   6  */
   7
   8 #include <linux/gcd.h>
   9 #include <linux/overflow.h>
  10
  11 #include <linux/iio/afe/rescale.h>
  12 #include <linux/iio/iio.h>
  13
  14 #include <kunit/test.h>
  15
  16 struct rescale_tc_data {
  17         const char *name;
  18
  19         const s32 numerator;
  20         const s32 denominator;
  21         const s32 offset;
  22
  23         const int schan_val;
  24         const int schan_val2;
  25         const int schan_off;
  26         const int schan_scale_type;
  27
  28         const char *expected;
  29         const char *expected_off;
  30 };
  31
  32 static const struct rescale_tc_data scale_cases[] = {
  33         /*
  34          * Typical use cases
  35          */
  36         {
  37                 .name = "typical IIO_VAL_INT, positive",
  38                 .numerator = 1000000,
  39                 .denominator = 8060,
  40                 .schan_scale_type = IIO_VAL_INT,
  41                 .schan_val = 42,
  42                 .expected = "5210.918114143",
  43         },
  44         {
  45                 .name = "typical IIO_VAL_INT, negative",
  46                 .numerator = -1000000,
  47                 .denominator = 8060,
  48                 .schan_scale_type = IIO_VAL_INT,
  49                 .schan_val = 42,
  50                 .expected = "-5210.918114143",
  51         },
  52         {
  53                 .name = "typical IIO_VAL_FRACTIONAL, positive",
  54                 .numerator = 1000000,
  55                 .denominator = 8060,
  56                 .schan_scale_type = IIO_VAL_FRACTIONAL,
  57                 .schan_val = 42,
  58                 .schan_val2 = 20,
  59                 .expected = "260.545905707",
  60         },
  61         {
  62                 .name = "typical IIO_VAL_FRACTIONAL, negative",
  63                 .numerator = -1000000,
  64                 .denominator = 8060,
  65                 .schan_scale_type = IIO_VAL_FRACTIONAL,
  66                 .schan_val = 42,
  67                 .schan_val2 = 20,
  68                 .expected = "-260.545905707",
  69         },
  70         {
  71                 .name = "typical IIO_VAL_FRACTIONAL_LOG2, positive",
  72                 .numerator = 42,
  73                 .denominator = 53,
  74                 .schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
  75                 .schan_val = 4096,
  76                 .schan_val2 = 16,
  77                 .expected = "0.049528301",
  78         },
  79         {
  80                 .name = "typical IIO_VAL_FRACTIONAL_LOG2, negative",
  81                 .numerator = -42,
  82                 .denominator = 53,
  83                 .schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
  84                 .schan_val = 4096,
  85                 .schan_val2 = 16,
  86                 .expected = "-0.049528301",
  87         },
  88         {
  89                 .name = "typical IIO_VAL_INT_PLUS_NANO, positive",
  90                 .numerator = 1000000,
  91                 .denominator = 8060,
  92                 .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
  93                 .schan_val = 10,
  94                 .schan_val2 = 123456,
  95                 .expected = "1240.710106203",
  96         },
  97         {
  98                 .name = "typical IIO_VAL_INT_PLUS_NANO, negative",
  99                 .numerator = -1000000,
 100                 .denominator = 8060,
 101                 .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
 102                 .schan_val = 10,
 103                 .schan_val2 = 123456,
 104                 .expected = "-1240.710106203",
 105         },
 106         {
 107                 .name = "typical IIO_VAL_INT_PLUS_MICRO, positive",
 108                 .numerator = 1000000,
 109                 .denominator = 8060,
 110                 .schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
 111                 .schan_val = 10,
 112                 .schan_val2 = 1234,
 113                 .expected = "1240.84789",
 114         },
 115         {
 116                 .name = "typical IIO_VAL_INT_PLUS_MICRO, negative",
 117                 .numerator = -1000000,
 118                 .denominator = 8060,
 119                 .schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
 120                 .schan_val = 10,
 121                 .schan_val2 = 1234,
 122                 .expected = "-1240.84789",
 123         },
 124         /*
 125          * Use cases with small scales involving divisions
 126          */
 127         {
 128                 .name = "small IIO_VAL_FRACTIONAL, 261/509 scaled by 90/1373754273",
 129                 .numerator = 261,
 130                 .denominator = 509,
 131                 .schan_scale_type = IIO_VAL_FRACTIONAL,
 132                 .schan_val = 90,
 133                 .schan_val2 = 1373754273,
 134                 .expected = "0.000000033594",
 135         },
 136         {
 137                 .name = "small IIO_VAL_FRACTIONAL, 90/1373754273 scaled by 261/509",
 138                 .numerator = 90,
 139                 .denominator = 1373754273,
 140                 .schan_scale_type = IIO_VAL_FRACTIONAL,
 141                 .schan_val = 261,
 142                 .schan_val2 = 509,
 143                 .expected = "0.000000033594",
 144         },
 145         {
 146                 .name = "small IIO_VAL_FRACTIONAL, 760/1373754273 scaled by 427/2727",
 147                 .numerator = 760,
 148                 .denominator = 1373754273,
 149                 .schan_scale_type = IIO_VAL_FRACTIONAL,
 150                 .schan_val = 427,
 151                 .schan_val2 = 2727,
 152                 .expected = "0.000000086626",
 153         },
 154         {
 155                 .name = "small IIO_VAL_FRACTIONAL, 761/1373754273 scaled by 427/2727",
 156                 .numerator = 761,
 157                 .denominator = 1373754273,
 158                 .schan_scale_type = IIO_VAL_FRACTIONAL,
 159                 .schan_val = 427,
 160                 .schan_val2 = 2727,
 161                 .expected = "0.000000086740",
 162         },
 163         {
 164                 .name = "small IIO_VAL_FRACTIONAL, 5/32768 scaled by 3/10000",
 165                 .numerator = 5,
 166                 .denominator = 32768,
 167                 .schan_scale_type = IIO_VAL_FRACTIONAL,
 168                 .schan_val = 3,
 169                 .schan_val2 = 10000,
 170                 .expected = "0.0000000457763671875",
 171         },
 172         {
 173                 .name = "small IIO_VAL_FRACTIONAL, 0 < scale < 1",
 174                 .numerator = 6,
 175                 .denominator = 6,
 176                 .schan_scale_type = IIO_VAL_FRACTIONAL,
 177                 .schan_val = 1,
 178                 .schan_val2 = 3,
 179                 .expected = "0.3333333333333333",
 180         },
 181         {
 182                 .name = "small IIO_VAL_FRACTIONAL, -1 < scale < 0",
 183                 .numerator = -6,
 184                 .denominator = 6,
 185                 .schan_scale_type = IIO_VAL_FRACTIONAL,
 186                 .schan_val = 1,
 187                 .schan_val2 = 3,
 188                 .expected = "-0.3333333333333333",
 189         },
 190         {
 191                 .name = "small IIO_VAL_FRACTIONAL, 0 < scale < 2",
 192                 .numerator = 8,
 193                 .denominator = 2,
 194                 .schan_scale_type = IIO_VAL_FRACTIONAL,
 195                 .schan_val = 1,
 196                 .schan_val2 = 3,
 197                 .expected = "1.3333333333333333",
 198         },
 199         {
 200                 .name = "small IIO_VAL_FRACTIONAL, -2 < scale < 0",
 201                 .numerator = -8,
 202                 .denominator = 2,
 203                 .schan_scale_type = IIO_VAL_FRACTIONAL,
 204                 .schan_val = 1,
 205                 .schan_val2 = 3,
 206                 .expected = "-1.3333333333333333",
 207         },
 208         {
 209                 .name = "small IIO_VAL_FRACTIONAL_LOG2, 760/32768 scaled by 15/22",
 210                 .numerator = 760,
 211                 .denominator = 32768,
 212                 .schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
 213                 .schan_val = 15,
 214                 .schan_val2 = 22,
 215                 .expected = "0.000000082946",
 216         },
 217         {
 218                 .name = "small IIO_VAL_FRACTIONAL_LOG2, 761/32768 scaled by 15/22",
 219                 .numerator = 761,
 220                 .denominator = 32768,
 221                 .schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
 222                 .schan_val = 15,
 223                 .schan_val2 = 22,
 224                 .expected = "0.000000083055",
 225         },
 226         {
 227                 .name = "small IIO_VAL_FRACTIONAL_LOG2, 0 < scale < 1",
 228                 .numerator = 16,
 229                 .denominator = 3,
 230                 .schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
 231                 .schan_val = 1,
 232                 .schan_val2 = 4,
 233                 .expected = "0.3333333333333333",
 234         },
 235         {
 236                 .name = "small IIO_VAL_FRACTIONAL_LOG2, -1 < scale < 0",
 237                 .numerator = -16,
 238                 .denominator = 3,
 239                 .schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
 240                 .schan_val = 1,
 241                 .schan_val2 = 4,
 242                 .expected = "-0.3333333333333333",
 243         },
 244         {
 245                 .name = "small IIO_VAL_FRACTIONAL_LOG2, 0 < scale < 2",
 246                 .numerator = 8,
 247                 .denominator = 3,
 248                 .schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
 249                 .schan_val = 1,
 250                 .schan_val2 = 1,
 251                 .expected = "1.3333333333333333",
 252         },
 253         {
 254                 .name = "small IIO_VAL_FRACTIONAL_LOG2, -2 < scale < 0",
 255                 .numerator = -8,
 256                 .denominator = 3,
 257                 .schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
 258                 .schan_val = 1,
 259                 .schan_val2 = 1,
 260                 .expected = "-1.3333333333333333",
 261         },
 262         {
 263                 .name = "small IIO_VAL_INT_PLUS_MICRO, positive",
 264                 .numerator = 1,
 265                 .denominator = 2,
 266                 .schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
 267                 .schan_val = 5,
 268                 .schan_val2 = 1234,
 269                 .expected = "2.500617",
 270         },
 271         {
 272                 .name = "small IIO_VAL_INT_PLUS_MICRO, negative",
 273                 .numerator = -1,
 274                 .denominator = 2,
 275                 .schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
 276                 .schan_val = 5,
 277                 .schan_val2 = 1234,
 278                 .expected = "-2.500617",
 279         },
 280         /*
 281          * INT_PLUS_{MICRO,NANO} positive/negative corner cases
 282          */
 283         {
 284                 .name = "negative IIO_VAL_INT_PLUS_NANO, negative schan",
 285                 .numerator = 1000000,
 286                 .denominator = 8060,
 287                 .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
 288                 .schan_val = -10,
 289                 .schan_val2 = 123456,
 290                 .expected = "-1240.710106203",
 291         },
 292         {
 293                 .name = "negative IIO_VAL_INT_PLUS_NANO, both negative",
 294                 .numerator = -1000000,
 295                 .denominator = 8060,
 296                 .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
 297                 .schan_val = -10,
 298                 .schan_val2 = 123456,
 299                 .expected = "1240.710106203",
 300         },
 301         {
 302                 .name = "negative IIO_VAL_INT_PLUS_NANO, 3 negative",
 303                 .numerator = -1000000,
 304                 .denominator = -8060,
 305                 .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
 306                 .schan_val = -10,
 307                 .schan_val2 = 123456,
 308                 .expected = "-1240.710106203",
 309         },
 310         {
 311                 .name = "negative IIO_VAL_INT_PLUS_NANO, 4 negative",
 312                 .numerator = -1000000,
 313                 .denominator = -8060,
 314                 .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
 315                 .schan_val = -10,
 316                 .schan_val2 = -123456,
 317                 .expected = "-1240.710106203",
 318         },
 319         {
 320                 .name = "negative IIO_VAL_INT_PLUS_NANO, negative, *val = 0",
 321                 .numerator = 1,
 322                 .denominator = -10,
 323                 .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
 324                 .schan_val = 0,
 325                 .schan_val2 = 123456789,
 326                 .expected = "-0.012345678",
 327         },
 328         /*
 329          * INT_PLUS_{MICRO,NANO} decimal part overflow
 330          */
 331         {
 332                 .name = "decimal overflow IIO_VAL_INT_PLUS_NANO, positive",
 333                 .numerator = 1000000,
 334                 .denominator = 8060,
 335                 .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
 336                 .schan_val = 10,
 337                 .schan_val2 = 123456789,
 338                 .expected = "1256.01200856",
 339         },
 340         {
 341                 .name = "decimal overflow IIO_VAL_INT_PLUS_NANO, negative",
 342                 .numerator = -1000000,
 343                 .denominator = 8060,
 344                 .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
 345                 .schan_val = 10,
 346                 .schan_val2 = 123456789,
 347                 .expected = "-1256.01200856",
 348         },
 349         {
 350                 .name = "decimal overflow IIO_VAL_INT_PLUS_NANO, negative schan",
 351                 .numerator = 1000000,
 352                 .denominator = 8060,
 353                 .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
 354                 .schan_val = -10,
 355                 .schan_val2 = 123456789,
 356                 .expected = "-1256.01200856",
 357         },
 358         {
 359                 .name = "decimal overflow IIO_VAL_INT_PLUS_MICRO, positive",
 360                 .numerator = 1000000,
 361                 .denominator = 8060,
 362                 .schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
 363                 .schan_val = 10,
 364                 .schan_val2 = 123456789,
 365                 .expected = "16557.914267",
 366         },
 367         {
 368                 .name = "decimal overflow IIO_VAL_INT_PLUS_MICRO, negative",
 369                 .numerator = -1000000,
 370                 .denominator = 8060,
 371                 .schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
 372                 .schan_val = 10,
 373                 .schan_val2 = 123456789,
 374                 .expected = "-16557.914267",
 375         },
 376         {
 377                 .name = "decimal overflow IIO_VAL_INT_PLUS_MICRO, negative schan",
 378                 .numerator = 1000000,
 379                 .denominator = 8060,
 380                 .schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
 381                 .schan_val = -10,
 382                 .schan_val2 = 123456789,
 383                 .expected = "-16557.914267",
 384         },
 385         /*
 386          * 32-bit overflow conditions
 387          */
 388         {
 389                 .name = "overflow IIO_VAL_FRACTIONAL, positive",
 390                 .numerator = 2,
 391                 .denominator = 20,
 392                 .schan_scale_type = IIO_VAL_FRACTIONAL,
 393                 .schan_val = S32_MAX,
 394                 .schan_val2 = 1,
 395                 .expected = "214748364.7",
 396         },
 397         {
 398                 .name = "overflow IIO_VAL_FRACTIONAL, negative",
 399                 .numerator = -2,
 400                 .denominator = 20,
 401                 .schan_scale_type = IIO_VAL_FRACTIONAL,
 402                 .schan_val = S32_MAX,
 403                 .schan_val2 = 1,
 404                 .expected = "-214748364.7",
 405         },
 406         {
 407                 .name = "overflow IIO_VAL_FRACTIONAL_LOG2, positive",
 408                 .numerator = S32_MAX,
 409                 .denominator = 4096,
 410                 .schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
 411                 .schan_val = 4096,
 412                 .schan_val2 = 16,
 413                 .expected = "32767.99998474121",
 414         },
 415         {
 416                 .name = "overflow IIO_VAL_FRACTIONAL_LOG2, negative",
 417                 .numerator = S32_MAX,
 418                 .denominator = 4096,
 419                 .schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
 420                 .schan_val = -4096,
 421                 .schan_val2 = 16,
 422                 .expected = "-32767.99998474121",
 423         },
 424         {
 425                 .name = "overflow IIO_VAL_INT_PLUS_NANO, positive",
 426                 .numerator = 2,
 427                 .denominator = 20,
 428                 .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
 429                 .schan_val = 10,
 430                 .schan_val2 = S32_MAX,
 431                 .expected = "1.214748364",
 432         },
 433         {
 434                 .name = "overflow IIO_VAL_INT_PLUS_NANO, negative",
 435                 .numerator = -2,
 436                 .denominator = 20,
 437                 .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
 438                 .schan_val = 10,
 439                 .schan_val2 = S32_MAX,
 440                 .expected = "-1.214748364",
 441         },
 442         {
 443                 .name = "overflow IIO_VAL_INT_PLUS_NANO, negative schan",
 444                 .numerator = 2,
 445                 .denominator = 20,
 446                 .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
 447                 .schan_val = -10,
 448                 .schan_val2 = S32_MAX,
 449                 .expected = "-1.214748364",
 450         },
 451         {
 452                 .name = "overflow IIO_VAL_INT_PLUS_MICRO, positive",
 453                 .numerator = 2,
 454                 .denominator = 20,
 455                 .schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
 456                 .schan_val = 10,
 457                 .schan_val2 = S32_MAX,
 458                 .expected = "215.748364",
 459         },
 460         {
 461                 .name = "overflow IIO_VAL_INT_PLUS_MICRO, negative",
 462                 .numerator = -2,
 463                 .denominator = 20,
 464                 .schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
 465                 .schan_val = 10,
 466                 .schan_val2 = S32_MAX,
 467                 .expected = "-215.748364",
 468         },
 469         {
 470                 .name = "overflow IIO_VAL_INT_PLUS_MICRO, negative schan",
 471                 .numerator = 2,
 472                 .denominator = 20,
 473                 .schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
 474                 .schan_val = -10,
 475                 .schan_val2 = S32_MAX,
 476                 .expected = "-215.748364",
 477         },
 478 };
 479
 480 static const struct rescale_tc_data offset_cases[] = {
 481         /*
 482          * Typical use cases
 483          */
 484         {
 485                 .name = "typical IIO_VAL_INT, positive",
 486                 .offset = 1234,
 487                 .schan_scale_type = IIO_VAL_INT,
 488                 .schan_val = 123,
 489                 .schan_val2 = 0,
 490                 .schan_off = 14,
 491                 .expected_off = "24", /* 23.872 */
 492         },
 493         {
 494                 .name = "typical IIO_VAL_INT, negative",
 495                 .offset = -1234,
 496                 .schan_scale_type = IIO_VAL_INT,
 497                 .schan_val = 12,
 498                 .schan_val2 = 0,
 499                 .schan_off = 14,
 500                 .expected_off = "-88", /* -88.83333333333333 */
 501         },
 502         {
 503                 .name = "typical IIO_VAL_FRACTIONAL, positive",
 504                 .offset = 1234,
 505                 .schan_scale_type = IIO_VAL_FRACTIONAL,
 506                 .schan_val = 12,
 507                 .schan_val2 = 34,
 508                 .schan_off = 14,
 509                 .expected_off = "3510", /* 3510.333333333333 */
 510         },
 511         {
 512                 .name = "typical IIO_VAL_FRACTIONAL, negative",
 513                 .offset = -1234,
 514                 .schan_scale_type = IIO_VAL_FRACTIONAL,
 515                 .schan_val = 12,
 516                 .schan_val2 = 34,
 517                 .schan_off = 14,
 518                 .expected_off = "-3482", /* -3482.333333333333 */
 519         },
 520         {
 521                 .name = "typical IIO_VAL_FRACTIONAL_LOG2, positive",
 522                 .offset = 1234,
 523                 .schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
 524                 .schan_val = 12,
 525                 .schan_val2 = 16,
 526                 .schan_off = 14,
 527                 .expected_off = "6739299", /* 6739299.333333333 */
 528         },
 529         {
 530                 .name = "typical IIO_VAL_FRACTIONAL_LOG2, negative",
 531                 .offset = -1234,
 532                 .schan_scale_type = IIO_VAL_FRACTIONAL_LOG2,
 533                 .schan_val = 12,
 534                 .schan_val2 = 16,
 535                 .schan_off = 14,
 536                 .expected_off = "-6739271", /* -6739271.333333333 */
 537         },
 538         {
 539                 .name = "typical IIO_VAL_INT_PLUS_NANO, positive",
 540                 .offset = 1234,
 541                 .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
 542                 .schan_val = 10,
 543                 .schan_val2 = 123456789,
 544                 .schan_off = 14,
 545                 .expected_off = "135", /* 135.8951219647469 */
 546         },
 547         {
 548                 .name = "typical IIO_VAL_INT_PLUS_NANO, negative",
 549                 .offset = -1234,
 550                 .schan_scale_type = IIO_VAL_INT_PLUS_NANO,
 551                 .schan_val = 10,
 552                 .schan_val2 = 123456789,
 553                 .schan_off = 14,
 554                 .expected_off = "-107", /* -107.89512196474689 */
 555         },
 556         {
 557                 .name = "typical IIO_VAL_INT_PLUS_MICRO, positive",
 558                 .offset = 1234,
 559                 .schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
 560                 .schan_val = 10,
 561                 .schan_val2 = 123456789,
 562                 .schan_off = 14,
 563                 .expected_off = "23", /* 23.246438560723952 */
 564         },
 565         {
 566                 .name = "typical IIO_VAL_INT_PLUS_MICRO, negative",
 567                 .offset = -12345,
 568                 .schan_scale_type = IIO_VAL_INT_PLUS_MICRO,
 569                 .schan_val = 10,
 570                 .schan_val2 = 123456789,
 571                 .schan_off = 14,
 572                 .expected_off = "-78", /* -78.50185091745313 */
 573         },
 574 };
 575
 576 static void case_to_desc(const struct rescale_tc_data *t, char *desc)
 577 {
 578         strcpy(desc, t->name);
 579 }
 580
 581 KUNIT_ARRAY_PARAM(iio_rescale_scale, scale_cases, case_to_desc);
 582 KUNIT_ARRAY_PARAM(iio_rescale_offset, offset_cases, case_to_desc);
 583
 584 /**
 585  * iio_str_to_nano() - Parse a fixed-point string to get an
 586  *                      IIO_VAL_INT_PLUS_NANO value
 587  * @str: The string to parse
 588  * @nano: The number as an integer
 589  *
 590  * Returns 0 on success, or a negative error code if the string cound not be
 591  * parsed.
 592  */
 593 static int iio_str_to_nano(const char *str, s64 *nano)
 594 {
 595         int tmp, tmp2;
 596         int ret = 0;
 597
 598         /*
 599          * iio_str_to_fixpoint() uses 10^8 here instead of 10^9 as fract_mult is
 600          * the multiplier for the first decimal place.
 601          */
 602         ret = iio_str_to_fixpoint(str, 100000000, &tmp, &tmp2);
 603         if (ret < 0)
 604                 return ret;
 605
 606         if (tmp < 0)
 607                 tmp2 *= -1;
 608
 609         *nano = (s64)tmp * 1000000000UL + tmp2;
 610
 611         return ret;
 612 }
 613
 614 /**
 615  * iio_test_relative_error_ppm() - Compute relative error (in parts-per-million)
 616  *                                 between two fixed-point strings
 617  * @real_str: The real value as a string
 618  * @exp_str: The expected value as a string
 619  *
 620  * Returns a negative error code if the strings cound not be parsed, or the
 621  * relative error in parts-per-million.
 622  */
 623 static int iio_test_relative_error_ppm(const char *real_str, const char *exp_str)
 624 {
 625         s64 real, exp, err;
 626         int ret;
 627
 628         ret = iio_str_to_nano(real_str, &real);
 629         if (ret < 0)
 630                 return ret;
 631
 632         ret = iio_str_to_nano(exp_str, &exp);
 633         if (ret < 0)
 634                 return ret;
 635
 636         if (!exp) {
 637                 pr_err("Expected value is null, relative error is undefined\n");
 638                 return -EINVAL;
 639         }
 640
 641         err = 1000000UL * abs(exp - real);
 642
 643         return (int)div64_u64(err, abs(exp));
 644 }
 645
 646 static void iio_rescale_test_scale(struct kunit *test)
 647 {
 648         struct rescale_tc_data *t = (struct rescale_tc_data *)test->param_value;
 649         char *buff = kunit_kmalloc(test, PAGE_SIZE, GFP_KERNEL);
 650         struct rescale rescale;
 651         int values[2];
 652         int rel_ppm;
 653         int ret;
 654
 655         rescale.numerator = t->numerator;
 656         rescale.denominator = t->denominator;
 657         rescale.offset = t->offset;
 658         values[0] = t->schan_val;
 659         values[1] = t->schan_val2;
 660
 661         ret = rescale_process_scale(&rescale, t->schan_scale_type,
 662                                     &values[0], &values[1]);
 663
 664         ret = iio_format_value(buff, ret, 2, values);
 665         KUNIT_EXPECT_EQ(test, (int)strlen(buff), ret);
 666
 667         rel_ppm = iio_test_relative_error_ppm(buff, t->expected);
 668         KUNIT_EXPECT_GE_MSG(test, rel_ppm, 0, "failed to compute ppm\n");
 669
 670         KUNIT_EXPECT_EQ_MSG(test, rel_ppm, 0,
 671                             "\t    real=%s"
 672                             "\texpected=%s\n",
 673                             buff, t->expected);
 674 }
 675
 676 static void iio_rescale_test_offset(struct kunit *test)
 677 {
 678         struct rescale_tc_data *t = (struct rescale_tc_data *)test->param_value;
 679         char *buff_off = kunit_kmalloc(test, PAGE_SIZE, GFP_KERNEL);
 680         struct rescale rescale;
 681         int values[2];
 682         int ret;
 683
 684         rescale.numerator = t->numerator;
 685         rescale.denominator = t->denominator;
 686         rescale.offset = t->offset;
 687         values[0] = t->schan_val;
 688         values[1] = t->schan_val2;
 689
 690         ret = rescale_process_offset(&rescale, t->schan_scale_type,
 691                                      t->schan_val, t->schan_val2, t->schan_off,
 692                                      &values[0], &values[1]);
 693
 694         ret = iio_format_value(buff_off, ret, 2, values);
 695         KUNIT_EXPECT_EQ(test, (int)strlen(buff_off), ret);
 696
 697         KUNIT_EXPECT_STREQ(test, strim(buff_off), t->expected_off);
 698 }
 699
 700 static struct kunit_case iio_rescale_test_cases[] = {
 701         KUNIT_CASE_PARAM(iio_rescale_test_scale, iio_rescale_scale_gen_params),
 702         KUNIT_CASE_PARAM(iio_rescale_test_offset, iio_rescale_offset_gen_params),
 703         {}
 704 };
 705
 706 static struct kunit_suite iio_rescale_test_suite = {
 707         .name = "iio-rescale",
 708         .test_cases = iio_rescale_test_cases,
 709 };
 710 kunit_test_suite(iio_rescale_test_suite);
 711
 712 MODULE_AUTHOR("Liam Beguin <liambeguin@gmail.com>");
 713 MODULE_DESCRIPTION("Test IIO rescale conversion functions");
 714 MODULE_LICENSE("GPL v2");
 715 MODULE_IMPORT_NS(IIO_RESCALE);