drivers/mtd/nand/raw/omap_elm.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Error Location Module
   4  *
   5  * Copyright (C) 2012 Texas Instruments Incorporated - https://www.ti.com/
   6  */
   7
   8 #define DRIVER_NAME     "omap-elm"
   9
  10 #include <linux/platform_device.h>
  11 #include <linux/module.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/io.h>
  14 #include <linux/of.h>
  15 #include <linux/sched.h>
  16 #include <linux/pm_runtime.h>
  17 #include <linux/platform_data/elm.h>
  18
  19 #define ELM_SYSCONFIG                   0x010
  20 #define ELM_IRQSTATUS                   0x018
  21 #define ELM_IRQENABLE                   0x01c
  22 #define ELM_LOCATION_CONFIG             0x020
  23 #define ELM_PAGE_CTRL                   0x080
  24 #define ELM_SYNDROME_FRAGMENT_0         0x400
  25 #define ELM_SYNDROME_FRAGMENT_1         0x404
  26 #define ELM_SYNDROME_FRAGMENT_2         0x408
  27 #define ELM_SYNDROME_FRAGMENT_3         0x40c
  28 #define ELM_SYNDROME_FRAGMENT_4         0x410
  29 #define ELM_SYNDROME_FRAGMENT_5         0x414
  30 #define ELM_SYNDROME_FRAGMENT_6         0x418
  31 #define ELM_LOCATION_STATUS             0x800
  32 #define ELM_ERROR_LOCATION_0            0x880
  33
  34 /* ELM Interrupt Status Register */
  35 #define INTR_STATUS_PAGE_VALID          BIT(8)
  36
  37 /* ELM Interrupt Enable Register */
  38 #define INTR_EN_PAGE_MASK               BIT(8)
  39
  40 /* ELM Location Configuration Register */
  41 #define ECC_BCH_LEVEL_MASK              0x3
  42
  43 /* ELM syndrome */
  44 #define ELM_SYNDROME_VALID              BIT(16)
  45
  46 /* ELM_LOCATION_STATUS Register */
  47 #define ECC_CORRECTABLE_MASK            BIT(8)
  48 #define ECC_NB_ERRORS_MASK              0x1f
  49
  50 /* ELM_ERROR_LOCATION_0-15 Registers */
  51 #define ECC_ERROR_LOCATION_MASK         0x1fff
  52
  53 #define ELM_ECC_SIZE                    0x7ff
  54
  55 #define SYNDROME_FRAGMENT_REG_SIZE      0x40
  56 #define ERROR_LOCATION_SIZE             0x100
  57
  58 struct elm_registers {
  59         u32 elm_irqenable;
  60         u32 elm_sysconfig;
  61         u32 elm_location_config;
  62         u32 elm_page_ctrl;
  63         u32 elm_syndrome_fragment_6[ERROR_VECTOR_MAX];
  64         u32 elm_syndrome_fragment_5[ERROR_VECTOR_MAX];
  65         u32 elm_syndrome_fragment_4[ERROR_VECTOR_MAX];
  66         u32 elm_syndrome_fragment_3[ERROR_VECTOR_MAX];
  67         u32 elm_syndrome_fragment_2[ERROR_VECTOR_MAX];
  68         u32 elm_syndrome_fragment_1[ERROR_VECTOR_MAX];
  69         u32 elm_syndrome_fragment_0[ERROR_VECTOR_MAX];
  70 };
  71
  72 struct elm_info {
  73         struct device *dev;
  74         void __iomem *elm_base;
  75         struct completion elm_completion;
  76         struct list_head list;
  77         enum bch_ecc bch_type;
  78         struct elm_registers elm_regs;
  79         int ecc_steps;
  80         int ecc_syndrome_size;
  81 };
  82
  83 static LIST_HEAD(elm_devices);
  84
  85 static void elm_write_reg(struct elm_info *info, int offset, u32 val)
  86 {
  87         writel(val, info->elm_base + offset);
  88 }
  89
  90 static u32 elm_read_reg(struct elm_info *info, int offset)
  91 {
  92         return readl(info->elm_base + offset);
  93 }
  94
  95 /**
  96  * elm_config - Configure ELM module
  97  * @dev:        ELM device
  98  * @bch_type:   Type of BCH ecc
  99  */
 100 int elm_config(struct device *dev, enum bch_ecc bch_type,
 101         int ecc_steps, int ecc_step_size, int ecc_syndrome_size)
 102 {
 103         u32 reg_val;
 104         struct elm_info *info = dev_get_drvdata(dev);
 105
 106         if (!info) {
 107                 dev_err(dev, "Unable to configure elm - device not probed?\n");
 108                 return -EPROBE_DEFER;
 109         }
 110         /* ELM cannot detect ECC errors for chunks > 1KB */
 111         if (ecc_step_size > ((ELM_ECC_SIZE + 1) / 2)) {
 112                 dev_err(dev, "unsupported config ecc-size=%d\n", ecc_step_size);
 113                 return -EINVAL;
 114         }
 115         /* ELM support 8 error syndrome process */
 116         if (ecc_steps > ERROR_VECTOR_MAX) {
 117                 dev_err(dev, "unsupported config ecc-step=%d\n", ecc_steps);
 118                 return -EINVAL;
 119         }
 120
 121         reg_val = (bch_type & ECC_BCH_LEVEL_MASK) | (ELM_ECC_SIZE << 16);
 122         elm_write_reg(info, ELM_LOCATION_CONFIG, reg_val);
 123         info->bch_type          = bch_type;
 124         info->ecc_steps         = ecc_steps;
 125         info->ecc_syndrome_size = ecc_syndrome_size;
 126
 127         return 0;
 128 }
 129 EXPORT_SYMBOL(elm_config);
 130
 131 /**
 132  * elm_configure_page_mode - Enable/Disable page mode
 133  * @info:       elm info
 134  * @index:      index number of syndrome fragment vector
 135  * @enable:     enable/disable flag for page mode
 136  *
 137  * Enable page mode for syndrome fragment index
 138  */
 139 static void elm_configure_page_mode(struct elm_info *info, int index,
 140                 bool enable)
 141 {
 142         u32 reg_val;
 143
 144         reg_val = elm_read_reg(info, ELM_PAGE_CTRL);
 145         if (enable)
 146                 reg_val |= BIT(index);  /* enable page mode */
 147         else
 148                 reg_val &= ~BIT(index); /* disable page mode */
 149
 150         elm_write_reg(info, ELM_PAGE_CTRL, reg_val);
 151 }
 152
 153 /**
 154  * elm_load_syndrome - Load ELM syndrome reg
 155  * @info:       elm info
 156  * @err_vec:    elm error vectors
 157  * @ecc:        buffer with calculated ecc
 158  *
 159  * Load syndrome fragment registers with calculated ecc in reverse order.
 160  */
 161 static void elm_load_syndrome(struct elm_info *info,
 162                 struct elm_errorvec *err_vec, u8 *ecc)
 163 {
 164         int i, offset;
 165         u32 val;
 166
 167         for (i = 0; i < info->ecc_steps; i++) {
 168
 169                 /* Check error reported */
 170                 if (err_vec[i].error_reported) {
 171                         elm_configure_page_mode(info, i, true);
 172                         offset = ELM_SYNDROME_FRAGMENT_0 +
 173                                 SYNDROME_FRAGMENT_REG_SIZE * i;
 174                         switch (info->bch_type) {
 175                         case BCH8_ECC:
 176                                 /* syndrome fragment 0 = ecc[9-12B] */
 177                                 val = (__force u32)cpu_to_be32(*(u32 *)&ecc[9]);
 178                                 elm_write_reg(info, offset, val);
 179
 180                                 /* syndrome fragment 1 = ecc[5-8B] */
 181                                 offset += 4;
 182                                 val = (__force u32)cpu_to_be32(*(u32 *)&ecc[5]);
 183                                 elm_write_reg(info, offset, val);
 184
 185                                 /* syndrome fragment 2 = ecc[1-4B] */
 186                                 offset += 4;
 187                                 val = (__force u32)cpu_to_be32(*(u32 *)&ecc[1]);
 188                                 elm_write_reg(info, offset, val);
 189
 190                                 /* syndrome fragment 3 = ecc[0B] */
 191                                 offset += 4;
 192                                 val = ecc[0];
 193                                 elm_write_reg(info, offset, val);
 194                                 break;
 195                         case BCH4_ECC:
 196                                 /* syndrome fragment 0 = ecc[20-52b] bits */
 197                                 val = ((__force u32)cpu_to_be32(*(u32 *)&ecc[3]) >> 4) |
 198                                         ((ecc[2] & 0xf) << 28);
 199                                 elm_write_reg(info, offset, val);
 200
 201                                 /* syndrome fragment 1 = ecc[0-20b] bits */
 202                                 offset += 4;
 203                                 val = (__force u32)cpu_to_be32(*(u32 *)&ecc[0]) >> 12;
 204                                 elm_write_reg(info, offset, val);
 205                                 break;
 206                         case BCH16_ECC:
 207                                 val = (__force u32)cpu_to_be32(*(u32 *)&ecc[22]);
 208                                 elm_write_reg(info, offset, val);
 209                                 offset += 4;
 210                                 val = (__force u32)cpu_to_be32(*(u32 *)&ecc[18]);
 211                                 elm_write_reg(info, offset, val);
 212                                 offset += 4;
 213                                 val = (__force u32)cpu_to_be32(*(u32 *)&ecc[14]);
 214                                 elm_write_reg(info, offset, val);
 215                                 offset += 4;
 216                                 val = (__force u32)cpu_to_be32(*(u32 *)&ecc[10]);
 217                                 elm_write_reg(info, offset, val);
 218                                 offset += 4;
 219                                 val = (__force u32)cpu_to_be32(*(u32 *)&ecc[6]);
 220                                 elm_write_reg(info, offset, val);
 221                                 offset += 4;
 222                                 val = (__force u32)cpu_to_be32(*(u32 *)&ecc[2]);
 223                                 elm_write_reg(info, offset, val);
 224                                 offset += 4;
 225                                 val = (__force u32)cpu_to_be32(*(u32 *)&ecc[0]) >> 16;
 226                                 elm_write_reg(info, offset, val);
 227                                 break;
 228                         default:
 229                                 pr_err("invalid config bch_type\n");
 230                         }
 231                 }
 232
 233                 /* Update ecc pointer with ecc byte size */
 234                 ecc += info->ecc_syndrome_size;
 235         }
 236 }
 237
 238 /**
 239  * elm_start_processing - start elm syndrome processing
 240  * @info:       elm info
 241  * @err_vec:    elm error vectors
 242  *
 243  * Set syndrome valid bit for syndrome fragment registers for which
 244  * elm syndrome fragment registers are loaded. This enables elm module
 245  * to start processing syndrome vectors.
 246  */
 247 static void elm_start_processing(struct elm_info *info,
 248                 struct elm_errorvec *err_vec)
 249 {
 250         int i, offset;
 251         u32 reg_val;
 252
 253         /*
 254          * Set syndrome vector valid, so that ELM module
 255          * will process it for vectors error is reported
 256          */
 257         for (i = 0; i < info->ecc_steps; i++) {
 258                 if (err_vec[i].error_reported) {
 259                         offset = ELM_SYNDROME_FRAGMENT_6 +
 260                                 SYNDROME_FRAGMENT_REG_SIZE * i;
 261                         reg_val = elm_read_reg(info, offset);
 262                         reg_val |= ELM_SYNDROME_VALID;
 263                         elm_write_reg(info, offset, reg_val);
 264                 }
 265         }
 266 }
 267
 268 /**
 269  * elm_error_correction - locate correctable error position
 270  * @info:       elm info
 271  * @err_vec:    elm error vectors
 272  *
 273  * On completion of processing by elm module, error location status
 274  * register updated with correctable/uncorrectable error information.
 275  * In case of correctable errors, number of errors located from
 276  * elm location status register & read the positions from
 277  * elm error location register.
 278  */
 279 static void elm_error_correction(struct elm_info *info,
 280                 struct elm_errorvec *err_vec)
 281 {
 282         int i, j, errors = 0;
 283         int offset;
 284         u32 reg_val;
 285
 286         for (i = 0; i < info->ecc_steps; i++) {
 287
 288                 /* Check error reported */
 289                 if (err_vec[i].error_reported) {
 290                         offset = ELM_LOCATION_STATUS + ERROR_LOCATION_SIZE * i;
 291                         reg_val = elm_read_reg(info, offset);
 292
 293                         /* Check correctable error or not */
 294                         if (reg_val & ECC_CORRECTABLE_MASK) {
 295                                 offset = ELM_ERROR_LOCATION_0 +
 296                                         ERROR_LOCATION_SIZE * i;
 297
 298                                 /* Read count of correctable errors */
 299                                 err_vec[i].error_count = reg_val &
 300                                         ECC_NB_ERRORS_MASK;
 301
 302                                 /* Update the error locations in error vector */
 303                                 for (j = 0; j < err_vec[i].error_count; j++) {
 304
 305                                         reg_val = elm_read_reg(info, offset);
 306                                         err_vec[i].error_loc[j] = reg_val &
 307                                                 ECC_ERROR_LOCATION_MASK;
 308
 309                                         /* Update error location register */
 310                                         offset += 4;
 311                                 }
 312
 313                                 errors += err_vec[i].error_count;
 314                         } else {
 315                                 err_vec[i].error_uncorrectable = true;
 316                         }
 317
 318                         /* Clearing interrupts for processed error vectors */
 319                         elm_write_reg(info, ELM_IRQSTATUS, BIT(i));
 320
 321                         /* Disable page mode */
 322                         elm_configure_page_mode(info, i, false);
 323                 }
 324         }
 325 }
 326
 327 /**
 328  * elm_decode_bch_error_page - Locate error position
 329  * @dev:        device pointer
 330  * @ecc_calc:   calculated ECC bytes from GPMC
 331  * @err_vec:    elm error vectors
 332  *
 333  * Called with one or more error reported vectors & vectors with
 334  * error reported is updated in err_vec[].error_reported
 335  */
 336 void elm_decode_bch_error_page(struct device *dev, u8 *ecc_calc,
 337                 struct elm_errorvec *err_vec)
 338 {
 339         struct elm_info *info = dev_get_drvdata(dev);
 340         u32 reg_val;
 341
 342         /* Enable page mode interrupt */
 343         reg_val = elm_read_reg(info, ELM_IRQSTATUS);
 344         elm_write_reg(info, ELM_IRQSTATUS, reg_val & INTR_STATUS_PAGE_VALID);
 345         elm_write_reg(info, ELM_IRQENABLE, INTR_EN_PAGE_MASK);
 346
 347         /* Load valid ecc byte to syndrome fragment register */
 348         elm_load_syndrome(info, err_vec, ecc_calc);
 349
 350         /* Enable syndrome processing for which syndrome fragment is updated */
 351         elm_start_processing(info, err_vec);
 352
 353         /* Wait for ELM module to finish locating error correction */
 354         wait_for_completion(&info->elm_completion);
 355
 356         /* Disable page mode interrupt */
 357         reg_val = elm_read_reg(info, ELM_IRQENABLE);
 358         elm_write_reg(info, ELM_IRQENABLE, reg_val & ~INTR_EN_PAGE_MASK);
 359         elm_error_correction(info, err_vec);
 360 }
 361 EXPORT_SYMBOL(elm_decode_bch_error_page);
 362
 363 static irqreturn_t elm_isr(int this_irq, void *dev_id)
 364 {
 365         u32 reg_val;
 366         struct elm_info *info = dev_id;
 367
 368         reg_val = elm_read_reg(info, ELM_IRQSTATUS);
 369
 370         /* All error vectors processed */
 371         if (reg_val & INTR_STATUS_PAGE_VALID) {
 372                 elm_write_reg(info, ELM_IRQSTATUS,
 373                                 reg_val & INTR_STATUS_PAGE_VALID);
 374                 complete(&info->elm_completion);
 375                 return IRQ_HANDLED;
 376         }
 377
 378         return IRQ_NONE;
 379 }
 380
 381 static int elm_probe(struct platform_device *pdev)
 382 {
 383         int ret = 0;
 384         struct resource *res, *irq;
 385         struct elm_info *info;
 386
 387         info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
 388         if (!info)
 389                 return -ENOMEM;
 390
 391         info->dev = &pdev->dev;
 392
 393         irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 394         if (!irq) {
 395                 dev_err(&pdev->dev, "no irq resource defined\n");
 396                 return -ENODEV;
 397         }
 398
 399         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 400         info->elm_base = devm_ioremap_resource(&pdev->dev, res);
 401         if (IS_ERR(info->elm_base))
 402                 return PTR_ERR(info->elm_base);
 403
 404         ret = devm_request_irq(&pdev->dev, irq->start, elm_isr, 0,
 405                         pdev->name, info);
 406         if (ret) {
 407                 dev_err(&pdev->dev, "failure requesting %pr\n", irq);
 408                 return ret;
 409         }
 410
 411         pm_runtime_enable(&pdev->dev);
 412         if (pm_runtime_get_sync(&pdev->dev) < 0) {
 413                 ret = -EINVAL;
 414                 pm_runtime_put_sync(&pdev->dev);
 415                 pm_runtime_disable(&pdev->dev);
 416                 dev_err(&pdev->dev, "can't enable clock\n");
 417                 return ret;
 418         }
 419
 420         init_completion(&info->elm_completion);
 421         INIT_LIST_HEAD(&info->list);
 422         list_add(&info->list, &elm_devices);
 423         platform_set_drvdata(pdev, info);
 424         return ret;
 425 }
 426
 427 static int elm_remove(struct platform_device *pdev)
 428 {
 429         pm_runtime_put_sync(&pdev->dev);
 430         pm_runtime_disable(&pdev->dev);
 431         return 0;
 432 }
 433
 434 #ifdef CONFIG_PM_SLEEP
 435 /**
 436  * elm_context_save
 437  * saves ELM configurations to preserve them across Hardware powered-down
 438  */
 439 static int elm_context_save(struct elm_info *info)
 440 {
 441         struct elm_registers *regs = &info->elm_regs;
 442         enum bch_ecc bch_type = info->bch_type;
 443         u32 offset = 0, i;
 444
 445         regs->elm_irqenable       = elm_read_reg(info, ELM_IRQENABLE);
 446         regs->elm_sysconfig       = elm_read_reg(info, ELM_SYSCONFIG);
 447         regs->elm_location_config = elm_read_reg(info, ELM_LOCATION_CONFIG);
 448         regs->elm_page_ctrl       = elm_read_reg(info, ELM_PAGE_CTRL);
 449         for (i = 0; i < ERROR_VECTOR_MAX; i++) {
 450                 offset = i * SYNDROME_FRAGMENT_REG_SIZE;
 451                 switch (bch_type) {
 452                 case BCH16_ECC:
 453                         regs->elm_syndrome_fragment_6[i] = elm_read_reg(info,
 454                                         ELM_SYNDROME_FRAGMENT_6 + offset);
 455                         regs->elm_syndrome_fragment_5[i] = elm_read_reg(info,
 456                                         ELM_SYNDROME_FRAGMENT_5 + offset);
 457                         regs->elm_syndrome_fragment_4[i] = elm_read_reg(info,
 458                                         ELM_SYNDROME_FRAGMENT_4 + offset);
 459                         fallthrough;
 460                 case BCH8_ECC:
 461                         regs->elm_syndrome_fragment_3[i] = elm_read_reg(info,
 462                                         ELM_SYNDROME_FRAGMENT_3 + offset);
 463                         regs->elm_syndrome_fragment_2[i] = elm_read_reg(info,
 464                                         ELM_SYNDROME_FRAGMENT_2 + offset);
 465                         fallthrough;
 466                 case BCH4_ECC:
 467                         regs->elm_syndrome_fragment_1[i] = elm_read_reg(info,
 468                                         ELM_SYNDROME_FRAGMENT_1 + offset);
 469                         regs->elm_syndrome_fragment_0[i] = elm_read_reg(info,
 470                                         ELM_SYNDROME_FRAGMENT_0 + offset);
 471                         break;
 472                 default:
 473                         return -EINVAL;
 474                 }
 475                 /* ELM SYNDROME_VALID bit in SYNDROME_FRAGMENT_6[] needs
 476                  * to be saved for all BCH schemes*/
 477                 regs->elm_syndrome_fragment_6[i] = elm_read_reg(info,
 478                                         ELM_SYNDROME_FRAGMENT_6 + offset);
 479         }
 480         return 0;
 481 }
 482
 483 /**
 484  * elm_context_restore
 485  * writes configurations saved duing power-down back into ELM registers
 486  */
 487 static int elm_context_restore(struct elm_info *info)
 488 {
 489         struct elm_registers *regs = &info->elm_regs;
 490         enum bch_ecc bch_type = info->bch_type;
 491         u32 offset = 0, i;
 492
 493         elm_write_reg(info, ELM_IRQENABLE,       regs->elm_irqenable);
 494         elm_write_reg(info, ELM_SYSCONFIG,       regs->elm_sysconfig);
 495         elm_write_reg(info, ELM_LOCATION_CONFIG, regs->elm_location_config);
 496         elm_write_reg(info, ELM_PAGE_CTRL,       regs->elm_page_ctrl);
 497         for (i = 0; i < ERROR_VECTOR_MAX; i++) {
 498                 offset = i * SYNDROME_FRAGMENT_REG_SIZE;
 499                 switch (bch_type) {
 500                 case BCH16_ECC:
 501                         elm_write_reg(info, ELM_SYNDROME_FRAGMENT_6 + offset,
 502                                         regs->elm_syndrome_fragment_6[i]);
 503                         elm_write_reg(info, ELM_SYNDROME_FRAGMENT_5 + offset,
 504                                         regs->elm_syndrome_fragment_5[i]);
 505                         elm_write_reg(info, ELM_SYNDROME_FRAGMENT_4 + offset,
 506                                         regs->elm_syndrome_fragment_4[i]);
 507                         fallthrough;
 508                 case BCH8_ECC:
 509                         elm_write_reg(info, ELM_SYNDROME_FRAGMENT_3 + offset,
 510                                         regs->elm_syndrome_fragment_3[i]);
 511                         elm_write_reg(info, ELM_SYNDROME_FRAGMENT_2 + offset,
 512                                         regs->elm_syndrome_fragment_2[i]);
 513                         fallthrough;
 514                 case BCH4_ECC:
 515                         elm_write_reg(info, ELM_SYNDROME_FRAGMENT_1 + offset,
 516                                         regs->elm_syndrome_fragment_1[i]);
 517                         elm_write_reg(info, ELM_SYNDROME_FRAGMENT_0 + offset,
 518                                         regs->elm_syndrome_fragment_0[i]);
 519                         break;
 520                 default:
 521                         return -EINVAL;
 522                 }
 523                 /* ELM_SYNDROME_VALID bit to be set in last to trigger FSM */
 524                 elm_write_reg(info, ELM_SYNDROME_FRAGMENT_6 + offset,
 525                                         regs->elm_syndrome_fragment_6[i] &
 526                                                          ELM_SYNDROME_VALID);
 527         }
 528         return 0;
 529 }
 530
 531 static int elm_suspend(struct device *dev)
 532 {
 533         struct elm_info *info = dev_get_drvdata(dev);
 534         elm_context_save(info);
 535         pm_runtime_put_sync(dev);
 536         return 0;
 537 }
 538
 539 static int elm_resume(struct device *dev)
 540 {
 541         struct elm_info *info = dev_get_drvdata(dev);
 542         pm_runtime_get_sync(dev);
 543         elm_context_restore(info);
 544         return 0;
 545 }
 546 #endif
 547
 548 static SIMPLE_DEV_PM_OPS(elm_pm_ops, elm_suspend, elm_resume);
 549
 550 #ifdef CONFIG_OF
 551 static const struct of_device_id elm_of_match[] = {
 552         { .compatible = "ti,am3352-elm" },
 553         {},
 554 };
 555 MODULE_DEVICE_TABLE(of, elm_of_match);
 556 #endif
 557
 558 static struct platform_driver elm_driver = {
 559         .driver = {
 560                 .name   = DRIVER_NAME,
 561                 .of_match_table = of_match_ptr(elm_of_match),
 562                 .pm     = &elm_pm_ops,
 563         },
 564         .probe  = elm_probe,
 565         .remove = elm_remove,
 566 };
 567
 568 module_platform_driver(elm_driver);
 569
 570 MODULE_DESCRIPTION("ELM driver for BCH error correction");
 571 MODULE_AUTHOR("Texas Instruments");
 572 MODULE_ALIAS("platform:" DRIVER_NAME);
 573 MODULE_LICENSE("GPL v2");