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 #include <linux/platform_device.h>
  19 #include <linux/module.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/io.h>
  22 #include <linux/of.h>
  23 #include <linux/sched.h>
  24 #include <linux/pm_runtime.h>
  25 #include <linux/platform_data/elm.h>
  26
  27 #define ELM_SYSCONFIG                   0x010
  28 #define ELM_IRQSTATUS                   0x018
  29 #define ELM_IRQENABLE                   0x01c
  30 #define ELM_LOCATION_CONFIG             0x020
  31 #define ELM_PAGE_CTRL                   0x080
  32 #define ELM_SYNDROME_FRAGMENT_0         0x400
  33 #define ELM_SYNDROME_FRAGMENT_1         0x404
  34 #define ELM_SYNDROME_FRAGMENT_2         0x408
  35 #define ELM_SYNDROME_FRAGMENT_3         0x40c
  36 #define ELM_SYNDROME_FRAGMENT_4         0x410
  37 #define ELM_SYNDROME_FRAGMENT_5         0x414
  38 #define ELM_SYNDROME_FRAGMENT_6         0x418
  39 #define ELM_LOCATION_STATUS             0x800
  40 #define ELM_ERROR_LOCATION_0            0x880
  41
  42 /* ELM Interrupt Status Register */
  43 #define INTR_STATUS_PAGE_VALID          BIT(8)
  44
  45 /* ELM Interrupt Enable Register */
  46 #define INTR_EN_PAGE_MASK               BIT(8)
  47
  48 /* ELM Location Configuration Register */
  49 #define ECC_BCH_LEVEL_MASK              0x3
  50
  51 /* ELM syndrome */
  52 #define ELM_SYNDROME_VALID              BIT(16)
  53
  54 /* ELM_LOCATION_STATUS Register */
  55 #define ECC_CORRECTABLE_MASK            BIT(8)
  56 #define ECC_NB_ERRORS_MASK              0x1f
  57
  58 /* ELM_ERROR_LOCATION_0-15 Registers */
  59 #define ECC_ERROR_LOCATION_MASK         0x1fff
  60
  61 #define ELM_ECC_SIZE                    0x7ff
  62
  63 #define SYNDROME_FRAGMENT_REG_SIZE      0x40
  64 #define ERROR_LOCATION_SIZE             0x100
  65
  66 struct elm_registers {
  67         u32 elm_irqenable;
  68         u32 elm_sysconfig;
  69         u32 elm_location_config;
  70         u32 elm_page_ctrl;
  71         u32 elm_syndrome_fragment_6[ERROR_VECTOR_MAX];
  72         u32 elm_syndrome_fragment_5[ERROR_VECTOR_MAX];
  73         u32 elm_syndrome_fragment_4[ERROR_VECTOR_MAX];
  74         u32 elm_syndrome_fragment_3[ERROR_VECTOR_MAX];
  75         u32 elm_syndrome_fragment_2[ERROR_VECTOR_MAX];
  76         u32 elm_syndrome_fragment_1[ERROR_VECTOR_MAX];
  77         u32 elm_syndrome_fragment_0[ERROR_VECTOR_MAX];
  78 };
  79
  80 struct elm_info {
  81         struct device *dev;
  82         void __iomem *elm_base;
  83         struct completion elm_completion;
  84         struct list_head list;
  85         enum bch_ecc bch_type;
  86         struct elm_registers elm_regs;
  87 };
  88
  89 static LIST_HEAD(elm_devices);
  90
  91 static void elm_write_reg(struct elm_info *info, int offset, u32 val)
  92 {
  93         writel(val, info->elm_base + offset);
  94 }
  95
  96 static u32 elm_read_reg(struct elm_info *info, int offset)
  97 {
  98         return readl(info->elm_base + offset);
  99 }
 100
 101 /**
 102  * elm_config - Configure ELM module
 103  * @dev:        ELM device
 104  * @bch_type:   Type of BCH ecc
 105  */
 106 int elm_config(struct device *dev, enum bch_ecc bch_type)
 107 {
 108         u32 reg_val;
 109         struct elm_info *info = dev_get_drvdata(dev);
 110
 111         if (!info) {
 112                 dev_err(dev, "Unable to configure elm - device not probed?\n");
 113                 return -ENODEV;
 114         }
 115
 116         reg_val = (bch_type & ECC_BCH_LEVEL_MASK) | (ELM_ECC_SIZE << 16);
 117         elm_write_reg(info, ELM_LOCATION_CONFIG, reg_val);
 118         info->bch_type = bch_type;
 119
 120         return 0;
 121 }
 122 EXPORT_SYMBOL(elm_config);
 123
 124 /**
 125  * elm_configure_page_mode - Enable/Disable page mode
 126  * @info:       elm info
 127  * @index:      index number of syndrome fragment vector
 128  * @enable:     enable/disable flag for page mode
 129  *
 130  * Enable page mode for syndrome fragment index
 131  */
 132 static void elm_configure_page_mode(struct elm_info *info, int index,
 133                 bool enable)
 134 {
 135         u32 reg_val;
 136
 137         reg_val = elm_read_reg(info, ELM_PAGE_CTRL);
 138         if (enable)
 139                 reg_val |= BIT(index);  /* enable page mode */
 140         else
 141                 reg_val &= ~BIT(index); /* disable page mode */
 142
 143         elm_write_reg(info, ELM_PAGE_CTRL, reg_val);
 144 }
 145
 146 /**
 147  * elm_load_syndrome - Load ELM syndrome reg
 148  * @info:       elm info
 149  * @err_vec:    elm error vectors
 150  * @ecc:        buffer with calculated ecc
 151  *
 152  * Load syndrome fragment registers with calculated ecc in reverse order.
 153  */
 154 static void elm_load_syndrome(struct elm_info *info,
 155                 struct elm_errorvec *err_vec, u8 *ecc)
 156 {
 157         int i, offset;
 158         u32 val;
 159
 160         for (i = 0; i < ERROR_VECTOR_MAX; i++) {
 161
 162                 /* Check error reported */
 163                 if (err_vec[i].error_reported) {
 164                         elm_configure_page_mode(info, i, true);
 165                         offset = ELM_SYNDROME_FRAGMENT_0 +
 166                                 SYNDROME_FRAGMENT_REG_SIZE * i;
 167
 168                         /* BCH8 */
 169                         if (info->bch_type) {
 170
 171                                 /* syndrome fragment 0 = ecc[9-12B] */
 172                                 val = cpu_to_be32(*(u32 *) &ecc[9]);
 173                                 elm_write_reg(info, offset, val);
 174
 175                                 /* syndrome fragment 1 = ecc[5-8B] */
 176                                 offset += 4;
 177                                 val = cpu_to_be32(*(u32 *) &ecc[5]);
 178                                 elm_write_reg(info, offset, val);
 179
 180                                 /* syndrome fragment 2 = ecc[1-4B] */
 181                                 offset += 4;
 182                                 val = cpu_to_be32(*(u32 *) &ecc[1]);
 183                                 elm_write_reg(info, offset, val);
 184
 185                                 /* syndrome fragment 3 = ecc[0B] */
 186                                 offset += 4;
 187                                 val = ecc[0];
 188                                 elm_write_reg(info, offset, val);
 189                         } else {
 190                                 /* syndrome fragment 0 = ecc[20-52b] bits */
 191                                 val = (cpu_to_be32(*(u32 *) &ecc[3]) >> 4) |
 192                                         ((ecc[2] & 0xf) << 28);
 193                                 elm_write_reg(info, offset, val);
 194
 195                                 /* syndrome fragment 1 = ecc[0-20b] bits */
 196                                 offset += 4;
 197                                 val = cpu_to_be32(*(u32 *) &ecc[0]) >> 12;
 198                                 elm_write_reg(info, offset, val);
 199                         }
 200                 }
 201
 202                 /* Update ecc pointer with ecc byte size */
 203                 ecc += info->bch_type ? BCH8_SIZE : BCH4_SIZE;
 204         }
 205 }
 206
 207 /**
 208  * elm_start_processing - start elm syndrome processing
 209  * @info:       elm info
 210  * @err_vec:    elm error vectors
 211  *
 212  * Set syndrome valid bit for syndrome fragment registers for which
 213  * elm syndrome fragment registers are loaded. This enables elm module
 214  * to start processing syndrome vectors.
 215  */
 216 static void elm_start_processing(struct elm_info *info,
 217                 struct elm_errorvec *err_vec)
 218 {
 219         int i, offset;
 220         u32 reg_val;
 221
 222         /*
 223          * Set syndrome vector valid, so that ELM module
 224          * will process it for vectors error is reported
 225          */
 226         for (i = 0; i < ERROR_VECTOR_MAX; i++) {
 227                 if (err_vec[i].error_reported) {
 228                         offset = ELM_SYNDROME_FRAGMENT_6 +
 229                                 SYNDROME_FRAGMENT_REG_SIZE * i;
 230                         reg_val = elm_read_reg(info, offset);
 231                         reg_val |= ELM_SYNDROME_VALID;
 232                         elm_write_reg(info, offset, reg_val);
 233                 }
 234         }
 235 }
 236
 237 /**
 238  * elm_error_correction - locate correctable error position
 239  * @info:       elm info
 240  * @err_vec:    elm error vectors
 241  *
 242  * On completion of processing by elm module, error location status
 243  * register updated with correctable/uncorrectable error information.
 244  * In case of correctable errors, number of errors located from
 245  * elm location status register & read the positions from
 246  * elm error location register.
 247  */
 248 static void elm_error_correction(struct elm_info *info,
 249                 struct elm_errorvec *err_vec)
 250 {
 251         int i, j, errors = 0;
 252         int offset;
 253         u32 reg_val;
 254
 255         for (i = 0; i < ERROR_VECTOR_MAX; i++) {
 256
 257                 /* Check error reported */
 258                 if (err_vec[i].error_reported) {
 259                         offset = ELM_LOCATION_STATUS + ERROR_LOCATION_SIZE * i;
 260                         reg_val = elm_read_reg(info, offset);
 261
 262                         /* Check correctable error or not */
 263                         if (reg_val & ECC_CORRECTABLE_MASK) {
 264                                 offset = ELM_ERROR_LOCATION_0 +
 265                                         ERROR_LOCATION_SIZE * i;
 266
 267                                 /* Read count of correctable errors */
 268                                 err_vec[i].error_count = reg_val &
 269                                         ECC_NB_ERRORS_MASK;
 270
 271                                 /* Update the error locations in error vector */
 272                                 for (j = 0; j < err_vec[i].error_count; j++) {
 273
 274                                         reg_val = elm_read_reg(info, offset);
 275                                         err_vec[i].error_loc[j] = reg_val &
 276                                                 ECC_ERROR_LOCATION_MASK;
 277
 278                                         /* Update error location register */
 279                                         offset += 4;
 280                                 }
 281
 282                                 errors += err_vec[i].error_count;
 283                         } else {
 284                                 err_vec[i].error_uncorrectable = true;
 285                         }
 286
 287                         /* Clearing interrupts for processed error vectors */
 288                         elm_write_reg(info, ELM_IRQSTATUS, BIT(i));
 289
 290                         /* Disable page mode */
 291                         elm_configure_page_mode(info, i, false);
 292                 }
 293         }
 294 }
 295
 296 /**
 297  * elm_decode_bch_error_page - Locate error position
 298  * @dev:        device pointer
 299  * @ecc_calc:   calculated ECC bytes from GPMC
 300  * @err_vec:    elm error vectors
 301  *
 302  * Called with one or more error reported vectors & vectors with
 303  * error reported is updated in err_vec[].error_reported
 304  */
 305 void elm_decode_bch_error_page(struct device *dev, u8 *ecc_calc,
 306                 struct elm_errorvec *err_vec)
 307 {
 308         struct elm_info *info = dev_get_drvdata(dev);
 309         u32 reg_val;
 310
 311         /* Enable page mode interrupt */
 312         reg_val = elm_read_reg(info, ELM_IRQSTATUS);
 313         elm_write_reg(info, ELM_IRQSTATUS, reg_val & INTR_STATUS_PAGE_VALID);
 314         elm_write_reg(info, ELM_IRQENABLE, INTR_EN_PAGE_MASK);
 315
 316         /* Load valid ecc byte to syndrome fragment register */
 317         elm_load_syndrome(info, err_vec, ecc_calc);
 318
 319         /* Enable syndrome processing for which syndrome fragment is updated */
 320         elm_start_processing(info, err_vec);
 321
 322         /* Wait for ELM module to finish locating error correction */
 323         wait_for_completion(&info->elm_completion);
 324
 325         /* Disable page mode interrupt */
 326         reg_val = elm_read_reg(info, ELM_IRQENABLE);
 327         elm_write_reg(info, ELM_IRQENABLE, reg_val & ~INTR_EN_PAGE_MASK);
 328         elm_error_correction(info, err_vec);
 329 }
 330 EXPORT_SYMBOL(elm_decode_bch_error_page);
 331
 332 static irqreturn_t elm_isr(int this_irq, void *dev_id)
 333 {
 334         u32 reg_val;
 335         struct elm_info *info = dev_id;
 336
 337         reg_val = elm_read_reg(info, ELM_IRQSTATUS);
 338
 339         /* All error vectors processed */
 340         if (reg_val & INTR_STATUS_PAGE_VALID) {
 341                 elm_write_reg(info, ELM_IRQSTATUS,
 342                                 reg_val & INTR_STATUS_PAGE_VALID);
 343                 complete(&info->elm_completion);
 344                 return IRQ_HANDLED;
 345         }
 346
 347         return IRQ_NONE;
 348 }
 349
 350 static int elm_probe(struct platform_device *pdev)
 351 {
 352         int ret = 0;
 353         struct resource *res, *irq;
 354         struct elm_info *info;
 355
 356         info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
 357         if (!info) {
 358                 dev_err(&pdev->dev, "failed to allocate memory\n");
 359                 return -ENOMEM;
 360         }
 361
 362         info->dev = &pdev->dev;
 363
 364         irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 365         if (!irq) {
 366                 dev_err(&pdev->dev, "no irq resource defined\n");
 367                 return -ENODEV;
 368         }
 369
 370         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 371         info->elm_base = devm_ioremap_resource(&pdev->dev, res);
 372         if (IS_ERR(info->elm_base))
 373                 return PTR_ERR(info->elm_base);
 374
 375         ret = devm_request_irq(&pdev->dev, irq->start, elm_isr, 0,
 376                         pdev->name, info);
 377         if (ret) {
 378                 dev_err(&pdev->dev, "failure requesting irq %i\n", irq->start);
 379                 return ret;
 380         }
 381
 382         pm_runtime_enable(&pdev->dev);
 383         if (pm_runtime_get_sync(&pdev->dev)) {
 384                 ret = -EINVAL;
 385                 pm_runtime_disable(&pdev->dev);
 386                 dev_err(&pdev->dev, "can't enable clock\n");
 387                 return ret;
 388         }
 389
 390         init_completion(&info->elm_completion);
 391         INIT_LIST_HEAD(&info->list);
 392         list_add(&info->list, &elm_devices);
 393         platform_set_drvdata(pdev, info);
 394         return ret;
 395 }
 396
 397 static int elm_remove(struct platform_device *pdev)
 398 {
 399         pm_runtime_put_sync(&pdev->dev);
 400         pm_runtime_disable(&pdev->dev);
 401         return 0;
 402 }
 403
 404 /**
 405  * elm_context_save
 406  * saves ELM configurations to preserve them across Hardware powered-down
 407  */
 408 static int elm_context_save(struct elm_info *info)
 409 {
 410         struct elm_registers *regs = &info->elm_regs;
 411         enum bch_ecc bch_type = info->bch_type;
 412         u32 offset = 0, i;
 413
 414         regs->elm_irqenable       = elm_read_reg(info, ELM_IRQENABLE);
 415         regs->elm_sysconfig       = elm_read_reg(info, ELM_SYSCONFIG);
 416         regs->elm_location_config = elm_read_reg(info, ELM_LOCATION_CONFIG);
 417         regs->elm_page_ctrl       = elm_read_reg(info, ELM_PAGE_CTRL);
 418         for (i = 0; i < ERROR_VECTOR_MAX; i++) {
 419                 offset = i * SYNDROME_FRAGMENT_REG_SIZE;
 420                 switch (bch_type) {
 421                 case BCH8_ECC:
 422                         regs->elm_syndrome_fragment_3[i] = elm_read_reg(info,
 423                                         ELM_SYNDROME_FRAGMENT_3 + offset);
 424                         regs->elm_syndrome_fragment_2[i] = elm_read_reg(info,
 425                                         ELM_SYNDROME_FRAGMENT_2 + offset);
 426                 case BCH4_ECC:
 427                         regs->elm_syndrome_fragment_1[i] = elm_read_reg(info,
 428                                         ELM_SYNDROME_FRAGMENT_1 + offset);
 429                         regs->elm_syndrome_fragment_0[i] = elm_read_reg(info,
 430                                         ELM_SYNDROME_FRAGMENT_0 + offset);
 431                         break;
 432                 default:
 433                         return -EINVAL;
 434                 }
 435                 /* ELM SYNDROME_VALID bit in SYNDROME_FRAGMENT_6[] needs
 436                  * to be saved for all BCH schemes*/
 437                 regs->elm_syndrome_fragment_6[i] = elm_read_reg(info,
 438                                         ELM_SYNDROME_FRAGMENT_6 + offset);
 439         }
 440         return 0;
 441 }
 442
 443 /**
 444  * elm_context_restore
 445  * writes configurations saved duing power-down back into ELM registers
 446  */
 447 static int elm_context_restore(struct elm_info *info)
 448 {
 449         struct elm_registers *regs = &info->elm_regs;
 450         enum bch_ecc bch_type = info->bch_type;
 451         u32 offset = 0, i;
 452
 453         elm_write_reg(info, ELM_IRQENABLE,       regs->elm_irqenable);
 454         elm_write_reg(info, ELM_SYSCONFIG,       regs->elm_sysconfig);
 455         elm_write_reg(info, ELM_LOCATION_CONFIG, regs->elm_location_config);
 456         elm_write_reg(info, ELM_PAGE_CTRL,       regs->elm_page_ctrl);
 457         for (i = 0; i < ERROR_VECTOR_MAX; i++) {
 458                 offset = i * SYNDROME_FRAGMENT_REG_SIZE;
 459                 switch (bch_type) {
 460                 case BCH8_ECC:
 461                         elm_write_reg(info, ELM_SYNDROME_FRAGMENT_3 + offset,
 462                                         regs->elm_syndrome_fragment_3[i]);
 463                         elm_write_reg(info, ELM_SYNDROME_FRAGMENT_2 + offset,
 464                                         regs->elm_syndrome_fragment_2[i]);
 465                 case BCH4_ECC:
 466                         elm_write_reg(info, ELM_SYNDROME_FRAGMENT_1 + offset,
 467                                         regs->elm_syndrome_fragment_1[i]);
 468                         elm_write_reg(info, ELM_SYNDROME_FRAGMENT_0 + offset,
 469                                         regs->elm_syndrome_fragment_0[i]);
 470                         break;
 471                 default:
 472                         return -EINVAL;
 473                 }
 474                 /* ELM_SYNDROME_VALID bit to be set in last to trigger FSM */
 475                 elm_write_reg(info, ELM_SYNDROME_FRAGMENT_6 + offset,
 476                                         regs->elm_syndrome_fragment_6[i] &
 477                                                          ELM_SYNDROME_VALID);
 478         }
 479         return 0;
 480 }
 481
 482 static int elm_suspend(struct device *dev)
 483 {
 484         struct elm_info *info = dev_get_drvdata(dev);
 485         elm_context_save(info);
 486         pm_runtime_put_sync(dev);
 487         return 0;
 488 }
 489
 490 static int elm_resume(struct device *dev)
 491 {
 492         struct elm_info *info = dev_get_drvdata(dev);
 493         pm_runtime_get_sync(dev);
 494         elm_context_restore(info);
 495         return 0;
 496 }
 497
 498 static SIMPLE_DEV_PM_OPS(elm_pm_ops, elm_suspend, elm_resume);
 499
 500 #ifdef CONFIG_OF
 501 static const struct of_device_id elm_of_match[] = {
 502         { .compatible = "ti,am3352-elm" },
 503         {},
 504 };
 505 MODULE_DEVICE_TABLE(of, elm_of_match);
 506 #endif
 507
 508 static struct platform_driver elm_driver = {
 509         .driver = {
 510                 .name   = "elm",
 511                 .owner  = THIS_MODULE,
 512                 .of_match_table = of_match_ptr(elm_of_match),
 513                 .pm     = &elm_pm_ops,
 514         },
 515         .probe  = elm_probe,
 516         .remove = elm_remove,
 517 };
 518
 519 module_platform_driver(elm_driver);
 520
 521 MODULE_DESCRIPTION("ELM driver for BCH error correction");
 522 MODULE_AUTHOR("Texas Instruments");
 523 MODULE_ALIAS("platform: elm");
 524 MODULE_LICENSE("GPL v2");