drivers/mtd/devices/elm.c

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