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/pm_runtime.h>
  24 #include <linux/platform_data/elm.h>
  25
  26 #define ELM_IRQSTATUS                   0x018
  27 #define ELM_IRQENABLE                   0x01c
  28 #define ELM_LOCATION_CONFIG             0x020
  29 #define ELM_PAGE_CTRL                   0x080
  30 #define ELM_SYNDROME_FRAGMENT_0         0x400
  31 #define ELM_SYNDROME_FRAGMENT_6         0x418
  32 #define ELM_LOCATION_STATUS             0x800
  33 #define ELM_ERROR_LOCATION_0            0x880
  34
  35 /* ELM Interrupt Status Register */
  36 #define INTR_STATUS_PAGE_VALID          BIT(8)
  37
  38 /* ELM Interrupt Enable Register */
  39 #define INTR_EN_PAGE_MASK               BIT(8)
  40
  41 /* ELM Location Configuration Register */
  42 #define ECC_BCH_LEVEL_MASK              0x3
  43
  44 /* ELM syndrome */
  45 #define ELM_SYNDROME_VALID              BIT(16)
  46
  47 /* ELM_LOCATION_STATUS Register */
  48 #define ECC_CORRECTABLE_MASK            BIT(8)
  49 #define ECC_NB_ERRORS_MASK              0x1f
  50
  51 /* ELM_ERROR_LOCATION_0-15 Registers */
  52 #define ECC_ERROR_LOCATION_MASK         0x1fff
  53
  54 #define ELM_ECC_SIZE                    0x7ff
  55
  56 #define SYNDROME_FRAGMENT_REG_SIZE      0x40
  57 #define ERROR_LOCATION_SIZE             0x100
  58
  59 struct elm_info {
  60         struct device *dev;
  61         void __iomem *elm_base;
  62         struct completion elm_completion;
  63         struct list_head list;
  64         enum bch_ecc bch_type;
  65 };
  66
  67 static LIST_HEAD(elm_devices);
  68
  69 static void elm_write_reg(struct elm_info *info, int offset, u32 val)
  70 {
  71         writel(val, info->elm_base + offset);
  72 }
  73
  74 static u32 elm_read_reg(struct elm_info *info, int offset)
  75 {
  76         return readl(info->elm_base + offset);
  77 }
  78
  79 /**
  80  * elm_config - Configure ELM module
  81  * @dev:        ELM device
  82  * @bch_type:   Type of BCH ecc
  83  */
  84 int elm_config(struct device *dev, enum bch_ecc bch_type)
  85 {
  86         u32 reg_val;
  87         struct elm_info *info = dev_get_drvdata(dev);
  88
  89         if (!info) {
  90                 dev_err(dev, "Unable to configure elm - device not probed?\n");
  91                 return -ENODEV;
  92         }
  93
  94         reg_val = (bch_type & ECC_BCH_LEVEL_MASK) | (ELM_ECC_SIZE << 16);
  95         elm_write_reg(info, ELM_LOCATION_CONFIG, reg_val);
  96         info->bch_type = bch_type;
  97
  98         return 0;
  99 }
 100 EXPORT_SYMBOL(elm_config);
 101
 102 /**
 103  * elm_configure_page_mode - Enable/Disable page mode
 104  * @info:       elm info
 105  * @index:      index number of syndrome fragment vector
 106  * @enable:     enable/disable flag for page mode
 107  *
 108  * Enable page mode for syndrome fragment index
 109  */
 110 static void elm_configure_page_mode(struct elm_info *info, int index,
 111                 bool enable)
 112 {
 113         u32 reg_val;
 114
 115         reg_val = elm_read_reg(info, ELM_PAGE_CTRL);
 116         if (enable)
 117                 reg_val |= BIT(index);  /* enable page mode */
 118         else
 119                 reg_val &= ~BIT(index); /* disable page mode */
 120
 121         elm_write_reg(info, ELM_PAGE_CTRL, reg_val);
 122 }
 123
 124 /**
 125  * elm_load_syndrome - Load ELM syndrome reg
 126  * @info:       elm info
 127  * @err_vec:    elm error vectors
 128  * @ecc:        buffer with calculated ecc
 129  *
 130  * Load syndrome fragment registers with calculated ecc in reverse order.
 131  */
 132 static void elm_load_syndrome(struct elm_info *info,
 133                 struct elm_errorvec *err_vec, u8 *ecc)
 134 {
 135         int i, offset;
 136         u32 val;
 137
 138         for (i = 0; i < ERROR_VECTOR_MAX; i++) {
 139
 140                 /* Check error reported */
 141                 if (err_vec[i].error_reported) {
 142                         elm_configure_page_mode(info, i, true);
 143                         offset = ELM_SYNDROME_FRAGMENT_0 +
 144                                 SYNDROME_FRAGMENT_REG_SIZE * i;
 145
 146                         /* BCH8 */
 147                         if (info->bch_type) {
 148
 149                                 /* syndrome fragment 0 = ecc[9-12B] */
 150                                 val = cpu_to_be32(*(u32 *) &ecc[9]);
 151                                 elm_write_reg(info, offset, val);
 152
 153                                 /* syndrome fragment 1 = ecc[5-8B] */
 154                                 offset += 4;
 155                                 val = cpu_to_be32(*(u32 *) &ecc[5]);
 156                                 elm_write_reg(info, offset, val);
 157
 158                                 /* syndrome fragment 2 = ecc[1-4B] */
 159                                 offset += 4;
 160                                 val = cpu_to_be32(*(u32 *) &ecc[1]);
 161                                 elm_write_reg(info, offset, val);
 162
 163                                 /* syndrome fragment 3 = ecc[0B] */
 164                                 offset += 4;
 165                                 val = ecc[0];
 166                                 elm_write_reg(info, offset, val);
 167                         } else {
 168                                 /* syndrome fragment 0 = ecc[20-52b] bits */
 169                                 val = (cpu_to_be32(*(u32 *) &ecc[3]) >> 4) |
 170                                         ((ecc[2] & 0xf) << 28);
 171                                 elm_write_reg(info, offset, val);
 172
 173                                 /* syndrome fragment 1 = ecc[0-20b] bits */
 174                                 offset += 4;
 175                                 val = cpu_to_be32(*(u32 *) &ecc[0]) >> 12;
 176                                 elm_write_reg(info, offset, val);
 177                         }
 178                 }
 179
 180                 /* Update ecc pointer with ecc byte size */
 181                 ecc += info->bch_type ? BCH8_SIZE : BCH4_SIZE;
 182         }
 183 }
 184
 185 /**
 186  * elm_start_processing - start elm syndrome processing
 187  * @info:       elm info
 188  * @err_vec:    elm error vectors
 189  *
 190  * Set syndrome valid bit for syndrome fragment registers for which
 191  * elm syndrome fragment registers are loaded. This enables elm module
 192  * to start processing syndrome vectors.
 193  */
 194 static void elm_start_processing(struct elm_info *info,
 195                 struct elm_errorvec *err_vec)
 196 {
 197         int i, offset;
 198         u32 reg_val;
 199
 200         /*
 201          * Set syndrome vector valid, so that ELM module
 202          * will process it for vectors error is reported
 203          */
 204         for (i = 0; i < ERROR_VECTOR_MAX; i++) {
 205                 if (err_vec[i].error_reported) {
 206                         offset = ELM_SYNDROME_FRAGMENT_6 +
 207                                 SYNDROME_FRAGMENT_REG_SIZE * i;
 208                         reg_val = elm_read_reg(info, offset);
 209                         reg_val |= ELM_SYNDROME_VALID;
 210                         elm_write_reg(info, offset, reg_val);
 211                 }
 212         }
 213 }
 214
 215 /**
 216  * elm_error_correction - locate correctable error position
 217  * @info:       elm info
 218  * @err_vec:    elm error vectors
 219  *
 220  * On completion of processing by elm module, error location status
 221  * register updated with correctable/uncorrectable error information.
 222  * In case of correctable errors, number of errors located from
 223  * elm location status register & read the positions from
 224  * elm error location register.
 225  */
 226 static void elm_error_correction(struct elm_info *info,
 227                 struct elm_errorvec *err_vec)
 228 {
 229         int i, j, errors = 0;
 230         int offset;
 231         u32 reg_val;
 232
 233         for (i = 0; i < ERROR_VECTOR_MAX; i++) {
 234
 235                 /* Check error reported */
 236                 if (err_vec[i].error_reported) {
 237                         offset = ELM_LOCATION_STATUS + ERROR_LOCATION_SIZE * i;
 238                         reg_val = elm_read_reg(info, offset);
 239
 240                         /* Check correctable error or not */
 241                         if (reg_val & ECC_CORRECTABLE_MASK) {
 242                                 offset = ELM_ERROR_LOCATION_0 +
 243                                         ERROR_LOCATION_SIZE * i;
 244
 245                                 /* Read count of correctable errors */
 246                                 err_vec[i].error_count = reg_val &
 247                                         ECC_NB_ERRORS_MASK;
 248
 249                                 /* Update the error locations in error vector */
 250                                 for (j = 0; j < err_vec[i].error_count; j++) {
 251
 252                                         reg_val = elm_read_reg(info, offset);
 253                                         err_vec[i].error_loc[j] = reg_val &
 254                                                 ECC_ERROR_LOCATION_MASK;
 255
 256                                         /* Update error location register */
 257                                         offset += 4;
 258                                 }
 259
 260                                 errors += err_vec[i].error_count;
 261                         } else {
 262                                 err_vec[i].error_uncorrectable = true;
 263                         }
 264
 265                         /* Clearing interrupts for processed error vectors */
 266                         elm_write_reg(info, ELM_IRQSTATUS, BIT(i));
 267
 268                         /* Disable page mode */
 269                         elm_configure_page_mode(info, i, false);
 270                 }
 271         }
 272 }
 273
 274 /**
 275  * elm_decode_bch_error_page - Locate error position
 276  * @dev:        device pointer
 277  * @ecc_calc:   calculated ECC bytes from GPMC
 278  * @err_vec:    elm error vectors
 279  *
 280  * Called with one or more error reported vectors & vectors with
 281  * error reported is updated in err_vec[].error_reported
 282  */
 283 void elm_decode_bch_error_page(struct device *dev, u8 *ecc_calc,
 284                 struct elm_errorvec *err_vec)
 285 {
 286         struct elm_info *info = dev_get_drvdata(dev);
 287         u32 reg_val;
 288
 289         /* Enable page mode interrupt */
 290         reg_val = elm_read_reg(info, ELM_IRQSTATUS);
 291         elm_write_reg(info, ELM_IRQSTATUS, reg_val & INTR_STATUS_PAGE_VALID);
 292         elm_write_reg(info, ELM_IRQENABLE, INTR_EN_PAGE_MASK);
 293
 294         /* Load valid ecc byte to syndrome fragment register */
 295         elm_load_syndrome(info, err_vec, ecc_calc);
 296
 297         /* Enable syndrome processing for which syndrome fragment is updated */
 298         elm_start_processing(info, err_vec);
 299
 300         /* Wait for ELM module to finish locating error correction */
 301         wait_for_completion(&info->elm_completion);
 302
 303         /* Disable page mode interrupt */
 304         reg_val = elm_read_reg(info, ELM_IRQENABLE);
 305         elm_write_reg(info, ELM_IRQENABLE, reg_val & ~INTR_EN_PAGE_MASK);
 306         elm_error_correction(info, err_vec);
 307 }
 308 EXPORT_SYMBOL(elm_decode_bch_error_page);
 309
 310 static irqreturn_t elm_isr(int this_irq, void *dev_id)
 311 {
 312         u32 reg_val;
 313         struct elm_info *info = dev_id;
 314
 315         reg_val = elm_read_reg(info, ELM_IRQSTATUS);
 316
 317         /* All error vectors processed */
 318         if (reg_val & INTR_STATUS_PAGE_VALID) {
 319                 elm_write_reg(info, ELM_IRQSTATUS,
 320                                 reg_val & INTR_STATUS_PAGE_VALID);
 321                 complete(&info->elm_completion);
 322                 return IRQ_HANDLED;
 323         }
 324
 325         return IRQ_NONE;
 326 }
 327
 328 static int elm_probe(struct platform_device *pdev)
 329 {
 330         int ret = 0;
 331         struct resource *res, *irq;
 332         struct elm_info *info;
 333
 334         info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
 335         if (!info) {
 336                 dev_err(&pdev->dev, "failed to allocate memory\n");
 337                 return -ENOMEM;
 338         }
 339
 340         info->dev = &pdev->dev;
 341
 342         irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 343         if (!irq) {
 344                 dev_err(&pdev->dev, "no irq resource defined\n");
 345                 return -ENODEV;
 346         }
 347
 348         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 349         if (!res) {
 350                 dev_err(&pdev->dev, "no memory resource defined\n");
 351                 return -ENODEV;
 352         }
 353
 354         info->elm_base = devm_request_and_ioremap(&pdev->dev, res);
 355         if (!info->elm_base)
 356                 return -EADDRNOTAVAIL;
 357
 358         ret = devm_request_irq(&pdev->dev, irq->start, elm_isr, 0,
 359                         pdev->name, info);
 360         if (ret) {
 361                 dev_err(&pdev->dev, "failure requesting irq %i\n", irq->start);
 362                 return ret;
 363         }
 364
 365         pm_runtime_enable(&pdev->dev);
 366         if (pm_runtime_get_sync(&pdev->dev)) {
 367                 ret = -EINVAL;
 368                 pm_runtime_disable(&pdev->dev);
 369                 dev_err(&pdev->dev, "can't enable clock\n");
 370                 return ret;
 371         }
 372
 373         init_completion(&info->elm_completion);
 374         INIT_LIST_HEAD(&info->list);
 375         list_add(&info->list, &elm_devices);
 376         platform_set_drvdata(pdev, info);
 377         return ret;
 378 }
 379
 380 static int elm_remove(struct platform_device *pdev)
 381 {
 382         pm_runtime_put_sync(&pdev->dev);
 383         pm_runtime_disable(&pdev->dev);
 384         platform_set_drvdata(pdev, NULL);
 385         return 0;
 386 }
 387
 388 #ifdef CONFIG_OF
 389 static const struct of_device_id elm_of_match[] = {
 390         { .compatible = "ti,am3352-elm" },
 391         {},
 392 };
 393 MODULE_DEVICE_TABLE(of, elm_of_match);
 394 #endif
 395
 396 static struct platform_driver elm_driver = {
 397         .driver = {
 398                 .name   = "elm",
 399                 .owner  = THIS_MODULE,
 400                 .of_match_table = of_match_ptr(elm_of_match),
 401         },
 402         .probe  = elm_probe,
 403         .remove = elm_remove,
 404 };
 405
 406 module_platform_driver(elm_driver);
 407
 408 MODULE_DESCRIPTION("ELM driver for BCH error correction");
 409 MODULE_AUTHOR("Texas Instruments");
 410 MODULE_ALIAS("platform: elm");
 411 MODULE_LICENSE("GPL v2");