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