drivers/nvmem/core.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * nvmem framework core.
   4  *
   5  * Copyright (C) 2015 Srinivas Kandagatla <[email protected]>
   6  * Copyright (C) 2013 Maxime Ripard <[email protected]>
   7  */
   8
   9 #include <linux/device.h>
  10 #include <linux/export.h>
  11 #include <linux/fs.h>
  12 #include <linux/idr.h>
  13 #include <linux/init.h>
  14 #include <linux/kref.h>
  15 #include <linux/module.h>
  16 #include <linux/nvmem-consumer.h>
  17 #include <linux/nvmem-provider.h>
  18 #include <linux/of.h>
  19 #include <linux/slab.h>
  20
  21 struct nvmem_device {
  22         struct module           *owner;
  23         struct device           dev;
  24         int                     stride;
  25         int                     word_size;
  26         int                     id;
  27         struct kref             refcnt;
  28         size_t                  size;
  29         bool                    read_only;
  30         int                     flags;
  31         struct bin_attribute    eeprom;
  32         struct device           *base_dev;
  33         struct list_head        cells;
  34         nvmem_reg_read_t        reg_read;
  35         nvmem_reg_write_t       reg_write;
  36         void *priv;
  37 };
  38
  39 #define FLAG_COMPAT             BIT(0)
  40
  41 struct nvmem_cell {
  42         const char              *name;
  43         int                     offset;
  44         int                     bytes;
  45         int                     bit_offset;
  46         int                     nbits;
  47         struct nvmem_device     *nvmem;
  48         struct list_head        node;
  49 };
  50
  51 static DEFINE_MUTEX(nvmem_mutex);
  52 static DEFINE_IDA(nvmem_ida);
  53
  54 static DEFINE_MUTEX(nvmem_cell_mutex);
  55 static LIST_HEAD(nvmem_cell_tables);
  56
  57 static DEFINE_MUTEX(nvmem_lookup_mutex);
  58 static LIST_HEAD(nvmem_lookup_list);
  59
  60 static BLOCKING_NOTIFIER_HEAD(nvmem_notifier);
  61
  62 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  63 static struct lock_class_key eeprom_lock_key;
  64 #endif
  65
  66 #define to_nvmem_device(d) container_of(d, struct nvmem_device, dev)
  67 static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
  68                           void *val, size_t bytes)
  69 {
  70         if (nvmem->reg_read)
  71                 return nvmem->reg_read(nvmem->priv, offset, val, bytes);
  72
  73         return -EINVAL;
  74 }
  75
  76 static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
  77                            void *val, size_t bytes)
  78 {
  79         if (nvmem->reg_write)
  80                 return nvmem->reg_write(nvmem->priv, offset, val, bytes);
  81
  82         return -EINVAL;
  83 }
  84
  85 static ssize_t bin_attr_nvmem_read(struct file *filp, struct kobject *kobj,
  86                                     struct bin_attribute *attr,
  87                                     char *buf, loff_t pos, size_t count)
  88 {
  89         struct device *dev;
  90         struct nvmem_device *nvmem;
  91         int rc;
  92
  93         if (attr->private)
  94                 dev = attr->private;
  95         else
  96                 dev = container_of(kobj, struct device, kobj);
  97         nvmem = to_nvmem_device(dev);
  98
  99         /* Stop the user from reading */
 100         if (pos >= nvmem->size)
 101                 return 0;
 102
 103         if (count < nvmem->word_size)
 104                 return -EINVAL;
 105
 106         if (pos + count > nvmem->size)
 107                 count = nvmem->size - pos;
 108
 109         count = round_down(count, nvmem->word_size);
 110
 111         rc = nvmem_reg_read(nvmem, pos, buf, count);
 112
 113         if (rc)
 114                 return rc;
 115
 116         return count;
 117 }
 118
 119 static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj,
 120                                      struct bin_attribute *attr,
 121                                      char *buf, loff_t pos, size_t count)
 122 {
 123         struct device *dev;
 124         struct nvmem_device *nvmem;
 125         int rc;
 126
 127         if (attr->private)
 128                 dev = attr->private;
 129         else
 130                 dev = container_of(kobj, struct device, kobj);
 131         nvmem = to_nvmem_device(dev);
 132
 133         /* Stop the user from writing */
 134         if (pos >= nvmem->size)
 135                 return -EFBIG;
 136
 137         if (count < nvmem->word_size)
 138                 return -EINVAL;
 139
 140         if (pos + count > nvmem->size)
 141                 count = nvmem->size - pos;
 142
 143         count = round_down(count, nvmem->word_size);
 144
 145         rc = nvmem_reg_write(nvmem, pos, buf, count);
 146
 147         if (rc)
 148                 return rc;
 149
 150         return count;
 151 }
 152
 153 /* default read/write permissions */
 154 static struct bin_attribute bin_attr_rw_nvmem = {
 155         .attr   = {
 156                 .name   = "nvmem",
 157                 .mode   = 0644,
 158         },
 159         .read   = bin_attr_nvmem_read,
 160         .write  = bin_attr_nvmem_write,
 161 };
 162
 163 static struct bin_attribute *nvmem_bin_rw_attributes[] = {
 164         &bin_attr_rw_nvmem,
 165         NULL,
 166 };
 167
 168 static const struct attribute_group nvmem_bin_rw_group = {
 169         .bin_attrs      = nvmem_bin_rw_attributes,
 170 };
 171
 172 static const struct attribute_group *nvmem_rw_dev_groups[] = {
 173         &nvmem_bin_rw_group,
 174         NULL,
 175 };
 176
 177 /* read only permission */
 178 static struct bin_attribute bin_attr_ro_nvmem = {
 179         .attr   = {
 180                 .name   = "nvmem",
 181                 .mode   = 0444,
 182         },
 183         .read   = bin_attr_nvmem_read,
 184 };
 185
 186 static struct bin_attribute *nvmem_bin_ro_attributes[] = {
 187         &bin_attr_ro_nvmem,
 188         NULL,
 189 };
 190
 191 static const struct attribute_group nvmem_bin_ro_group = {
 192         .bin_attrs      = nvmem_bin_ro_attributes,
 193 };
 194
 195 static const struct attribute_group *nvmem_ro_dev_groups[] = {
 196         &nvmem_bin_ro_group,
 197         NULL,
 198 };
 199
 200 /* default read/write permissions, root only */
 201 static struct bin_attribute bin_attr_rw_root_nvmem = {
 202         .attr   = {
 203                 .name   = "nvmem",
 204                 .mode   = 0600,
 205         },
 206         .read   = bin_attr_nvmem_read,
 207         .write  = bin_attr_nvmem_write,
 208 };
 209
 210 static struct bin_attribute *nvmem_bin_rw_root_attributes[] = {
 211         &bin_attr_rw_root_nvmem,
 212         NULL,
 213 };
 214
 215 static const struct attribute_group nvmem_bin_rw_root_group = {
 216         .bin_attrs      = nvmem_bin_rw_root_attributes,
 217 };
 218
 219 static const struct attribute_group *nvmem_rw_root_dev_groups[] = {
 220         &nvmem_bin_rw_root_group,
 221         NULL,
 222 };
 223
 224 /* read only permission, root only */
 225 static struct bin_attribute bin_attr_ro_root_nvmem = {
 226         .attr   = {
 227                 .name   = "nvmem",
 228                 .mode   = 0400,
 229         },
 230         .read   = bin_attr_nvmem_read,
 231 };
 232
 233 static struct bin_attribute *nvmem_bin_ro_root_attributes[] = {
 234         &bin_attr_ro_root_nvmem,
 235         NULL,
 236 };
 237
 238 static const struct attribute_group nvmem_bin_ro_root_group = {
 239         .bin_attrs      = nvmem_bin_ro_root_attributes,
 240 };
 241
 242 static const struct attribute_group *nvmem_ro_root_dev_groups[] = {
 243         &nvmem_bin_ro_root_group,
 244         NULL,
 245 };
 246
 247 static void nvmem_release(struct device *dev)
 248 {
 249         struct nvmem_device *nvmem = to_nvmem_device(dev);
 250
 251         ida_simple_remove(&nvmem_ida, nvmem->id);
 252         kfree(nvmem);
 253 }
 254
 255 static const struct device_type nvmem_provider_type = {
 256         .release        = nvmem_release,
 257 };
 258
 259 static struct bus_type nvmem_bus_type = {
 260         .name           = "nvmem",
 261 };
 262
 263 static int of_nvmem_match(struct device *dev, void *nvmem_np)
 264 {
 265         return dev->of_node == nvmem_np;
 266 }
 267
 268 static struct nvmem_device *of_nvmem_find(struct device_node *nvmem_np)
 269 {
 270         struct device *d;
 271
 272         if (!nvmem_np)
 273                 return NULL;
 274
 275         d = bus_find_device(&nvmem_bus_type, NULL, nvmem_np, of_nvmem_match);
 276
 277         if (!d)
 278                 return NULL;
 279
 280         return to_nvmem_device(d);
 281 }
 282
 283 static struct nvmem_device *nvmem_find(const char *name)
 284 {
 285         struct device *d;
 286
 287         d = bus_find_device_by_name(&nvmem_bus_type, NULL, name);
 288
 289         if (!d)
 290                 return NULL;
 291
 292         return to_nvmem_device(d);
 293 }
 294
 295 static void nvmem_cell_drop(struct nvmem_cell *cell)
 296 {
 297         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_REMOVE, cell);
 298         mutex_lock(&nvmem_mutex);
 299         list_del(&cell->node);
 300         mutex_unlock(&nvmem_mutex);
 301         kfree(cell->name);
 302         kfree(cell);
 303 }
 304
 305 static void nvmem_device_remove_all_cells(const struct nvmem_device *nvmem)
 306 {
 307         struct nvmem_cell *cell, *p;
 308
 309         list_for_each_entry_safe(cell, p, &nvmem->cells, node)
 310                 nvmem_cell_drop(cell);
 311 }
 312
 313 static void nvmem_cell_add(struct nvmem_cell *cell)
 314 {
 315         mutex_lock(&nvmem_mutex);
 316         list_add_tail(&cell->node, &cell->nvmem->cells);
 317         mutex_unlock(&nvmem_mutex);
 318         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_ADD, cell);
 319 }
 320
 321 static int nvmem_cell_info_to_nvmem_cell(struct nvmem_device *nvmem,
 322                                    const struct nvmem_cell_info *info,
 323                                    struct nvmem_cell *cell)
 324 {
 325         cell->nvmem = nvmem;
 326         cell->offset = info->offset;
 327         cell->bytes = info->bytes;
 328         cell->name = info->name;
 329
 330         cell->bit_offset = info->bit_offset;
 331         cell->nbits = info->nbits;
 332
 333         if (cell->nbits)
 334                 cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
 335                                            BITS_PER_BYTE);
 336
 337         if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
 338                 dev_err(&nvmem->dev,
 339                         "cell %s unaligned to nvmem stride %d\n",
 340                         cell->name, nvmem->stride);
 341                 return -EINVAL;
 342         }
 343
 344         return 0;
 345 }
 346
 347 /**
 348  * nvmem_add_cells() - Add cell information to an nvmem device
 349  *
 350  * @nvmem: nvmem device to add cells to.
 351  * @info: nvmem cell info to add to the device
 352  * @ncells: number of cells in info
 353  *
 354  * Return: 0 or negative error code on failure.
 355  */
 356 static int nvmem_add_cells(struct nvmem_device *nvmem,
 357                     const struct nvmem_cell_info *info,
 358                     int ncells)
 359 {
 360         struct nvmem_cell **cells;
 361         int i, rval;
 362
 363         cells = kcalloc(ncells, sizeof(*cells), GFP_KERNEL);
 364         if (!cells)
 365                 return -ENOMEM;
 366
 367         for (i = 0; i < ncells; i++) {
 368                 cells[i] = kzalloc(sizeof(**cells), GFP_KERNEL);
 369                 if (!cells[i]) {
 370                         rval = -ENOMEM;
 371                         goto err;
 372                 }
 373
 374                 rval = nvmem_cell_info_to_nvmem_cell(nvmem, &info[i], cells[i]);
 375                 if (rval) {
 376                         kfree(cells[i]);
 377                         goto err;
 378                 }
 379
 380                 nvmem_cell_add(cells[i]);
 381         }
 382
 383         /* remove tmp array */
 384         kfree(cells);
 385
 386         return 0;
 387 err:
 388         while (i--)
 389                 nvmem_cell_drop(cells[i]);
 390
 391         kfree(cells);
 392
 393         return rval;
 394 }
 395
 396 /*
 397  * nvmem_setup_compat() - Create an additional binary entry in
 398  * drivers sys directory, to be backwards compatible with the older
 399  * drivers/misc/eeprom drivers.
 400  */
 401 static int nvmem_setup_compat(struct nvmem_device *nvmem,
 402                               const struct nvmem_config *config)
 403 {
 404         int rval;
 405
 406         if (!config->base_dev)
 407                 return -EINVAL;
 408
 409         if (nvmem->read_only)
 410                 nvmem->eeprom = bin_attr_ro_root_nvmem;
 411         else
 412                 nvmem->eeprom = bin_attr_rw_root_nvmem;
 413         nvmem->eeprom.attr.name = "eeprom";
 414         nvmem->eeprom.size = nvmem->size;
 415 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 416         nvmem->eeprom.attr.key = &eeprom_lock_key;
 417 #endif
 418         nvmem->eeprom.private = &nvmem->dev;
 419         nvmem->base_dev = config->base_dev;
 420
 421         rval = device_create_bin_file(nvmem->base_dev, &nvmem->eeprom);
 422         if (rval) {
 423                 dev_err(&nvmem->dev,
 424                         "Failed to create eeprom binary file %d\n", rval);
 425                 return rval;
 426         }
 427
 428         nvmem->flags |= FLAG_COMPAT;
 429
 430         return 0;
 431 }
 432
 433 /**
 434  * nvmem_register_notifier() - Register a notifier block for nvmem events.
 435  *
 436  * @nb: notifier block to be called on nvmem events.
 437  *
 438  * Return: 0 on success, negative error number on failure.
 439  */
 440 int nvmem_register_notifier(struct notifier_block *nb)
 441 {
 442         return blocking_notifier_chain_register(&nvmem_notifier, nb);
 443 }
 444 EXPORT_SYMBOL_GPL(nvmem_register_notifier);
 445
 446 /**
 447  * nvmem_unregister_notifier() - Unregister a notifier block for nvmem events.
 448  *
 449  * @nb: notifier block to be unregistered.
 450  *
 451  * Return: 0 on success, negative error number on failure.
 452  */
 453 int nvmem_unregister_notifier(struct notifier_block *nb)
 454 {
 455         return blocking_notifier_chain_unregister(&nvmem_notifier, nb);
 456 }
 457 EXPORT_SYMBOL_GPL(nvmem_unregister_notifier);
 458
 459 static int nvmem_add_cells_from_table(struct nvmem_device *nvmem)
 460 {
 461         const struct nvmem_cell_info *info;
 462         struct nvmem_cell_table *table;
 463         struct nvmem_cell *cell;
 464         int rval = 0, i;
 465
 466         mutex_lock(&nvmem_cell_mutex);
 467         list_for_each_entry(table, &nvmem_cell_tables, node) {
 468                 if (strcmp(nvmem_dev_name(nvmem), table->nvmem_name) == 0) {
 469                         for (i = 0; i < table->ncells; i++) {
 470                                 info = &table->cells[i];
 471
 472                                 cell = kzalloc(sizeof(*cell), GFP_KERNEL);
 473                                 if (!cell) {
 474                                         rval = -ENOMEM;
 475                                         goto out;
 476                                 }
 477
 478                                 rval = nvmem_cell_info_to_nvmem_cell(nvmem,
 479                                                                      info,
 480                                                                      cell);
 481                                 if (rval) {
 482                                         kfree(cell);
 483                                         goto out;
 484                                 }
 485
 486                                 nvmem_cell_add(cell);
 487                         }
 488                 }
 489         }
 490
 491 out:
 492         mutex_unlock(&nvmem_cell_mutex);
 493         return rval;
 494 }
 495
 496 static struct nvmem_cell *
 497 nvmem_find_cell_by_name(struct nvmem_device *nvmem, const char *cell_id)
 498 {
 499         struct nvmem_cell *cell = NULL;
 500
 501         mutex_lock(&nvmem_mutex);
 502         list_for_each_entry(cell, &nvmem->cells, node) {
 503                 if (strcmp(cell_id, cell->name) == 0)
 504                         break;
 505         }
 506         mutex_unlock(&nvmem_mutex);
 507
 508         return cell;
 509 }
 510
 511 static int nvmem_add_cells_from_of(struct nvmem_device *nvmem)
 512 {
 513         struct device_node *parent, *child;
 514         struct device *dev = &nvmem->dev;
 515         struct nvmem_cell *cell;
 516         const __be32 *addr;
 517         int len;
 518
 519         parent = dev->of_node;
 520
 521         for_each_child_of_node(parent, child) {
 522                 addr = of_get_property(child, "reg", &len);
 523                 if (!addr || (len < 2 * sizeof(u32))) {
 524                         dev_err(dev, "nvmem: invalid reg on %pOF\n", child);
 525                         return -EINVAL;
 526                 }
 527
 528                 cell = kzalloc(sizeof(*cell), GFP_KERNEL);
 529                 if (!cell)
 530                         return -ENOMEM;
 531
 532                 cell->nvmem = nvmem;
 533                 cell->offset = be32_to_cpup(addr++);
 534                 cell->bytes = be32_to_cpup(addr);
 535                 cell->name = kasprintf(GFP_KERNEL, "%pOFn", child);
 536
 537                 addr = of_get_property(child, "bits", &len);
 538                 if (addr && len == (2 * sizeof(u32))) {
 539                         cell->bit_offset = be32_to_cpup(addr++);
 540                         cell->nbits = be32_to_cpup(addr);
 541                 }
 542
 543                 if (cell->nbits)
 544                         cell->bytes = DIV_ROUND_UP(
 545                                         cell->nbits + cell->bit_offset,
 546                                         BITS_PER_BYTE);
 547
 548                 if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
 549                         dev_err(dev, "cell %s unaligned to nvmem stride %d\n",
 550                                 cell->name, nvmem->stride);
 551                         /* Cells already added will be freed later. */
 552                         kfree(cell->name);
 553                         kfree(cell);
 554                         return -EINVAL;
 555                 }
 556
 557                 nvmem_cell_add(cell);
 558         }
 559
 560         return 0;
 561 }
 562
 563 /**
 564  * nvmem_register() - Register a nvmem device for given nvmem_config.
 565  * Also creates an binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
 566  *
 567  * @config: nvmem device configuration with which nvmem device is created.
 568  *
 569  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
 570  * on success.
 571  */
 572
 573 struct nvmem_device *nvmem_register(const struct nvmem_config *config)
 574 {
 575         struct nvmem_device *nvmem;
 576         int rval;
 577
 578         if (!config->dev)
 579                 return ERR_PTR(-EINVAL);
 580
 581         nvmem = kzalloc(sizeof(*nvmem), GFP_KERNEL);
 582         if (!nvmem)
 583                 return ERR_PTR(-ENOMEM);
 584
 585         rval  = ida_simple_get(&nvmem_ida, 0, 0, GFP_KERNEL);
 586         if (rval < 0) {
 587                 kfree(nvmem);
 588                 return ERR_PTR(rval);
 589         }
 590
 591         kref_init(&nvmem->refcnt);
 592         INIT_LIST_HEAD(&nvmem->cells);
 593
 594         nvmem->id = rval;
 595         nvmem->owner = config->owner;
 596         if (!nvmem->owner && config->dev->driver)
 597                 nvmem->owner = config->dev->driver->owner;
 598         nvmem->stride = config->stride ?: 1;
 599         nvmem->word_size = config->word_size ?: 1;
 600         nvmem->size = config->size;
 601         nvmem->dev.type = &nvmem_provider_type;
 602         nvmem->dev.bus = &nvmem_bus_type;
 603         nvmem->dev.parent = config->dev;
 604         nvmem->priv = config->priv;
 605         nvmem->reg_read = config->reg_read;
 606         nvmem->reg_write = config->reg_write;
 607         nvmem->dev.of_node = config->dev->of_node;
 608
 609         if (config->id == -1 && config->name) {
 610                 dev_set_name(&nvmem->dev, "%s", config->name);
 611         } else {
 612                 dev_set_name(&nvmem->dev, "%s%d",
 613                              config->name ? : "nvmem",
 614                              config->name ? config->id : nvmem->id);
 615         }
 616
 617         nvmem->read_only = device_property_present(config->dev, "read-only") |
 618                            config->read_only;
 619
 620         if (config->root_only)
 621                 nvmem->dev.groups = nvmem->read_only ?
 622                         nvmem_ro_root_dev_groups :
 623                         nvmem_rw_root_dev_groups;
 624         else
 625                 nvmem->dev.groups = nvmem->read_only ?
 626                         nvmem_ro_dev_groups :
 627                         nvmem_rw_dev_groups;
 628
 629         device_initialize(&nvmem->dev);
 630
 631         dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
 632
 633         rval = device_add(&nvmem->dev);
 634         if (rval)
 635                 goto err_put_device;
 636
 637         if (config->compat) {
 638                 rval = nvmem_setup_compat(nvmem, config);
 639                 if (rval)
 640                         goto err_device_del;
 641         }
 642
 643         if (config->cells) {
 644                 rval = nvmem_add_cells(nvmem, config->cells, config->ncells);
 645                 if (rval)
 646                         goto err_teardown_compat;
 647         }
 648
 649         rval = nvmem_add_cells_from_table(nvmem);
 650         if (rval)
 651                 goto err_remove_cells;
 652
 653         rval = nvmem_add_cells_from_of(nvmem);
 654         if (rval)
 655                 goto err_remove_cells;
 656
 657         rval = blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem);
 658         if (rval)
 659                 goto err_remove_cells;
 660
 661         return nvmem;
 662
 663 err_remove_cells:
 664         nvmem_device_remove_all_cells(nvmem);
 665 err_teardown_compat:
 666         if (config->compat)
 667                 device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
 668 err_device_del:
 669         device_del(&nvmem->dev);
 670 err_put_device:
 671         put_device(&nvmem->dev);
 672
 673         return ERR_PTR(rval);
 674 }
 675 EXPORT_SYMBOL_GPL(nvmem_register);
 676
 677 static void nvmem_device_release(struct kref *kref)
 678 {
 679         struct nvmem_device *nvmem;
 680
 681         nvmem = container_of(kref, struct nvmem_device, refcnt);
 682
 683         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_REMOVE, nvmem);
 684
 685         if (nvmem->flags & FLAG_COMPAT)
 686                 device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
 687
 688         nvmem_device_remove_all_cells(nvmem);
 689         device_del(&nvmem->dev);
 690         put_device(&nvmem->dev);
 691 }
 692
 693 /**
 694  * nvmem_unregister() - Unregister previously registered nvmem device
 695  *
 696  * @nvmem: Pointer to previously registered nvmem device.
 697  */
 698 void nvmem_unregister(struct nvmem_device *nvmem)
 699 {
 700         kref_put(&nvmem->refcnt, nvmem_device_release);
 701 }
 702 EXPORT_SYMBOL_GPL(nvmem_unregister);
 703
 704 static void devm_nvmem_release(struct device *dev, void *res)
 705 {
 706         nvmem_unregister(*(struct nvmem_device **)res);
 707 }
 708
 709 /**
 710  * devm_nvmem_register() - Register a managed nvmem device for given
 711  * nvmem_config.
 712  * Also creates an binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
 713  *
 714  * @dev: Device that uses the nvmem device.
 715  * @config: nvmem device configuration with which nvmem device is created.
 716  *
 717  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
 718  * on success.
 719  */
 720 struct nvmem_device *devm_nvmem_register(struct device *dev,
 721                                          const struct nvmem_config *config)
 722 {
 723         struct nvmem_device **ptr, *nvmem;
 724
 725         ptr = devres_alloc(devm_nvmem_release, sizeof(*ptr), GFP_KERNEL);
 726         if (!ptr)
 727                 return ERR_PTR(-ENOMEM);
 728
 729         nvmem = nvmem_register(config);
 730
 731         if (!IS_ERR(nvmem)) {
 732                 *ptr = nvmem;
 733                 devres_add(dev, ptr);
 734         } else {
 735                 devres_free(ptr);
 736         }
 737
 738         return nvmem;
 739 }
 740 EXPORT_SYMBOL_GPL(devm_nvmem_register);
 741
 742 static int devm_nvmem_match(struct device *dev, void *res, void *data)
 743 {
 744         struct nvmem_device **r = res;
 745
 746         return *r == data;
 747 }
 748
 749 /**
 750  * devm_nvmem_unregister() - Unregister previously registered managed nvmem
 751  * device.
 752  *
 753  * @dev: Device that uses the nvmem device.
 754  * @nvmem: Pointer to previously registered nvmem device.
 755  *
 756  * Return: Will be an negative on error or a zero on success.
 757  */
 758 int devm_nvmem_unregister(struct device *dev, struct nvmem_device *nvmem)
 759 {
 760         return devres_release(dev, devm_nvmem_release, devm_nvmem_match, nvmem);
 761 }
 762 EXPORT_SYMBOL(devm_nvmem_unregister);
 763
 764 static struct nvmem_device *__nvmem_device_get(struct device_node *np,
 765                                                const char *nvmem_name)
 766 {
 767         struct nvmem_device *nvmem = NULL;
 768
 769         mutex_lock(&nvmem_mutex);
 770         nvmem = np ? of_nvmem_find(np) : nvmem_find(nvmem_name);
 771         mutex_unlock(&nvmem_mutex);
 772         if (!nvmem)
 773                 return ERR_PTR(-EPROBE_DEFER);
 774
 775         if (!try_module_get(nvmem->owner)) {
 776                 dev_err(&nvmem->dev,
 777                         "could not increase module refcount for cell %s\n",
 778                         nvmem_dev_name(nvmem));
 779
 780                 return ERR_PTR(-EINVAL);
 781         }
 782
 783         kref_get(&nvmem->refcnt);
 784
 785         return nvmem;
 786 }
 787
 788 static void __nvmem_device_put(struct nvmem_device *nvmem)
 789 {
 790         module_put(nvmem->owner);
 791         kref_put(&nvmem->refcnt, nvmem_device_release);
 792 }
 793
 794 #if IS_ENABLED(CONFIG_OF)
 795 /**
 796  * of_nvmem_device_get() - Get nvmem device from a given id
 797  *
 798  * @np: Device tree node that uses the nvmem device.
 799  * @id: nvmem name from nvmem-names property.
 800  *
 801  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
 802  * on success.
 803  */
 804 struct nvmem_device *of_nvmem_device_get(struct device_node *np, const char *id)
 805 {
 806
 807         struct device_node *nvmem_np;
 808         int index;
 809
 810         index = of_property_match_string(np, "nvmem-names", id);
 811
 812         nvmem_np = of_parse_phandle(np, "nvmem", index);
 813         if (!nvmem_np)
 814                 return ERR_PTR(-EINVAL);
 815
 816         return __nvmem_device_get(nvmem_np, NULL);
 817 }
 818 EXPORT_SYMBOL_GPL(of_nvmem_device_get);
 819 #endif
 820
 821 /**
 822  * nvmem_device_get() - Get nvmem device from a given id
 823  *
 824  * @dev: Device that uses the nvmem device.
 825  * @dev_name: name of the requested nvmem device.
 826  *
 827  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
 828  * on success.
 829  */
 830 struct nvmem_device *nvmem_device_get(struct device *dev, const char *dev_name)
 831 {
 832         if (dev->of_node) { /* try dt first */
 833                 struct nvmem_device *nvmem;
 834
 835                 nvmem = of_nvmem_device_get(dev->of_node, dev_name);
 836
 837                 if (!IS_ERR(nvmem) || PTR_ERR(nvmem) == -EPROBE_DEFER)
 838                         return nvmem;
 839
 840         }
 841
 842         return nvmem_find(dev_name);
 843 }
 844 EXPORT_SYMBOL_GPL(nvmem_device_get);
 845
 846 static int devm_nvmem_device_match(struct device *dev, void *res, void *data)
 847 {
 848         struct nvmem_device **nvmem = res;
 849
 850         if (WARN_ON(!nvmem || !*nvmem))
 851                 return 0;
 852
 853         return *nvmem == data;
 854 }
 855
 856 static void devm_nvmem_device_release(struct device *dev, void *res)
 857 {
 858         nvmem_device_put(*(struct nvmem_device **)res);
 859 }
 860
 861 /**
 862  * devm_nvmem_device_put() - put alredy got nvmem device
 863  *
 864  * @dev: Device that uses the nvmem device.
 865  * @nvmem: pointer to nvmem device allocated by devm_nvmem_cell_get(),
 866  * that needs to be released.
 867  */
 868 void devm_nvmem_device_put(struct device *dev, struct nvmem_device *nvmem)
 869 {
 870         int ret;
 871
 872         ret = devres_release(dev, devm_nvmem_device_release,
 873                              devm_nvmem_device_match, nvmem);
 874
 875         WARN_ON(ret);
 876 }
 877 EXPORT_SYMBOL_GPL(devm_nvmem_device_put);
 878
 879 /**
 880  * nvmem_device_put() - put alredy got nvmem device
 881  *
 882  * @nvmem: pointer to nvmem device that needs to be released.
 883  */
 884 void nvmem_device_put(struct nvmem_device *nvmem)
 885 {
 886         __nvmem_device_put(nvmem);
 887 }
 888 EXPORT_SYMBOL_GPL(nvmem_device_put);
 889
 890 /**
 891  * devm_nvmem_device_get() - Get nvmem cell of device form a given id
 892  *
 893  * @dev: Device that requests the nvmem device.
 894  * @id: name id for the requested nvmem device.
 895  *
 896  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_cell
 897  * on success.  The nvmem_cell will be freed by the automatically once the
 898  * device is freed.
 899  */
 900 struct nvmem_device *devm_nvmem_device_get(struct device *dev, const char *id)
 901 {
 902         struct nvmem_device **ptr, *nvmem;
 903
 904         ptr = devres_alloc(devm_nvmem_device_release, sizeof(*ptr), GFP_KERNEL);
 905         if (!ptr)
 906                 return ERR_PTR(-ENOMEM);
 907
 908         nvmem = nvmem_device_get(dev, id);
 909         if (!IS_ERR(nvmem)) {
 910                 *ptr = nvmem;
 911                 devres_add(dev, ptr);
 912         } else {
 913                 devres_free(ptr);
 914         }
 915
 916         return nvmem;
 917 }
 918 EXPORT_SYMBOL_GPL(devm_nvmem_device_get);
 919
 920 static struct nvmem_cell *
 921 nvmem_cell_get_from_lookup(struct device *dev, const char *con_id)
 922 {
 923         struct nvmem_cell *cell = ERR_PTR(-ENOENT);
 924         struct nvmem_cell_lookup *lookup;
 925         struct nvmem_device *nvmem;
 926         const char *dev_id;
 927
 928         if (!dev)
 929                 return ERR_PTR(-EINVAL);
 930
 931         dev_id = dev_name(dev);
 932
 933         mutex_lock(&nvmem_lookup_mutex);
 934
 935         list_for_each_entry(lookup, &nvmem_lookup_list, node) {
 936                 if ((strcmp(lookup->dev_id, dev_id) == 0) &&
 937                     (strcmp(lookup->con_id, con_id) == 0)) {
 938                         /* This is the right entry. */
 939                         nvmem = __nvmem_device_get(NULL, lookup->nvmem_name);
 940                         if (IS_ERR(nvmem)) {
 941                                 /* Provider may not be registered yet. */
 942                                 cell = ERR_CAST(nvmem);
 943                                 goto out;
 944                         }
 945
 946                         cell = nvmem_find_cell_by_name(nvmem,
 947                                                        lookup->cell_name);
 948                         if (!cell) {
 949                                 __nvmem_device_put(nvmem);
 950                                 cell = ERR_PTR(-ENOENT);
 951                                 goto out;
 952                         }
 953                 }
 954         }
 955
 956 out:
 957         mutex_unlock(&nvmem_lookup_mutex);
 958         return cell;
 959 }
 960
 961 #if IS_ENABLED(CONFIG_OF)
 962 static struct nvmem_cell *
 963 nvmem_find_cell_by_index(struct nvmem_device *nvmem, int index)
 964 {
 965         struct nvmem_cell *cell = NULL;
 966         int i = 0;
 967
 968         mutex_lock(&nvmem_mutex);
 969         list_for_each_entry(cell, &nvmem->cells, node) {
 970                 if (index == i++)
 971                         break;
 972         }
 973         mutex_unlock(&nvmem_mutex);
 974
 975         return cell;
 976 }
 977
 978 /**
 979  * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
 980  *
 981  * @np: Device tree node that uses the nvmem cell.
 982  * @id: nvmem cell name from nvmem-cell-names property, or NULL
 983  *      for the cell at index 0 (the lone cell with no accompanying
 984  *      nvmem-cell-names property).
 985  *
 986  * Return: Will be an ERR_PTR() on error or a valid pointer
 987  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
 988  * nvmem_cell_put().
 989  */
 990 struct nvmem_cell *of_nvmem_cell_get(struct device_node *np, const char *id)
 991 {
 992         struct device_node *cell_np, *nvmem_np;
 993         struct nvmem_device *nvmem;
 994         struct nvmem_cell *cell;
 995         int index = 0;
 996
 997         /* if cell name exists, find index to the name */
 998         if (id)
 999                 index = of_property_match_string(np, "nvmem-cell-names", id);
1000
1001         cell_np = of_parse_phandle(np, "nvmem-cells", index);
1002         if (!cell_np)
1003                 return ERR_PTR(-EINVAL);
1004
1005         nvmem_np = of_get_next_parent(cell_np);
1006         if (!nvmem_np)
1007                 return ERR_PTR(-EINVAL);
1008
1009         nvmem = __nvmem_device_get(nvmem_np, NULL);
1010         of_node_put(nvmem_np);
1011         if (IS_ERR(nvmem))
1012                 return ERR_CAST(nvmem);
1013
1014         cell = nvmem_find_cell_by_index(nvmem, index);
1015         if (!cell) {
1016                 __nvmem_device_put(nvmem);
1017                 return ERR_PTR(-ENOENT);
1018         }
1019
1020         return cell;
1021 }
1022 EXPORT_SYMBOL_GPL(of_nvmem_cell_get);
1023 #endif
1024
1025 /**
1026  * nvmem_cell_get() - Get nvmem cell of device form a given cell name
1027  *
1028  * @dev: Device that requests the nvmem cell.
1029  * @id: nvmem cell name to get (this corresponds with the name from the
1030  *      nvmem-cell-names property for DT systems and with the con_id from
1031  *      the lookup entry for non-DT systems).
1032  *
1033  * Return: Will be an ERR_PTR() on error or a valid pointer
1034  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1035  * nvmem_cell_put().
1036  */
1037 struct nvmem_cell *nvmem_cell_get(struct device *dev, const char *id)
1038 {
1039         struct nvmem_cell *cell;
1040
1041         if (dev->of_node) { /* try dt first */
1042                 cell = of_nvmem_cell_get(dev->of_node, id);
1043                 if (!IS_ERR(cell) || PTR_ERR(cell) == -EPROBE_DEFER)
1044                         return cell;
1045         }
1046
1047         /* NULL cell id only allowed for device tree; invalid otherwise */
1048         if (!id)
1049                 return ERR_PTR(-EINVAL);
1050
1051         return nvmem_cell_get_from_lookup(dev, id);
1052 }
1053 EXPORT_SYMBOL_GPL(nvmem_cell_get);
1054
1055 static void devm_nvmem_cell_release(struct device *dev, void *res)
1056 {
1057         nvmem_cell_put(*(struct nvmem_cell **)res);
1058 }
1059
1060 /**
1061  * devm_nvmem_cell_get() - Get nvmem cell of device form a given id
1062  *
1063  * @dev: Device that requests the nvmem cell.
1064  * @id: nvmem cell name id to get.
1065  *
1066  * Return: Will be an ERR_PTR() on error or a valid pointer
1067  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1068  * automatically once the device is freed.
1069  */
1070 struct nvmem_cell *devm_nvmem_cell_get(struct device *dev, const char *id)
1071 {
1072         struct nvmem_cell **ptr, *cell;
1073
1074         ptr = devres_alloc(devm_nvmem_cell_release, sizeof(*ptr), GFP_KERNEL);
1075         if (!ptr)
1076                 return ERR_PTR(-ENOMEM);
1077
1078         cell = nvmem_cell_get(dev, id);
1079         if (!IS_ERR(cell)) {
1080                 *ptr = cell;
1081                 devres_add(dev, ptr);
1082         } else {
1083                 devres_free(ptr);
1084         }
1085
1086         return cell;
1087 }
1088 EXPORT_SYMBOL_GPL(devm_nvmem_cell_get);
1089
1090 static int devm_nvmem_cell_match(struct device *dev, void *res, void *data)
1091 {
1092         struct nvmem_cell **c = res;
1093
1094         if (WARN_ON(!c || !*c))
1095                 return 0;
1096
1097         return *c == data;
1098 }
1099
1100 /**
1101  * devm_nvmem_cell_put() - Release previously allocated nvmem cell
1102  * from devm_nvmem_cell_get.
1103  *
1104  * @dev: Device that requests the nvmem cell.
1105  * @cell: Previously allocated nvmem cell by devm_nvmem_cell_get().
1106  */
1107 void devm_nvmem_cell_put(struct device *dev, struct nvmem_cell *cell)
1108 {
1109         int ret;
1110
1111         ret = devres_release(dev, devm_nvmem_cell_release,
1112                                 devm_nvmem_cell_match, cell);
1113
1114         WARN_ON(ret);
1115 }
1116 EXPORT_SYMBOL(devm_nvmem_cell_put);
1117
1118 /**
1119  * nvmem_cell_put() - Release previously allocated nvmem cell.
1120  *
1121  * @cell: Previously allocated nvmem cell by nvmem_cell_get().
1122  */
1123 void nvmem_cell_put(struct nvmem_cell *cell)
1124 {
1125         struct nvmem_device *nvmem = cell->nvmem;
1126
1127         __nvmem_device_put(nvmem);
1128 }
1129 EXPORT_SYMBOL_GPL(nvmem_cell_put);
1130
1131 static void nvmem_shift_read_buffer_in_place(struct nvmem_cell *cell, void *buf)
1132 {
1133         u8 *p, *b;
1134         int i, bit_offset = cell->bit_offset;
1135
1136         p = b = buf;
1137         if (bit_offset) {
1138                 /* First shift */
1139                 *b++ >>= bit_offset;
1140
1141                 /* setup rest of the bytes if any */
1142                 for (i = 1; i < cell->bytes; i++) {
1143                         /* Get bits from next byte and shift them towards msb */
1144                         *p |= *b << (BITS_PER_BYTE - bit_offset);
1145
1146                         p = b;
1147                         *b++ >>= bit_offset;
1148                 }
1149
1150                 /* result fits in less bytes */
1151                 if (cell->bytes != DIV_ROUND_UP(cell->nbits, BITS_PER_BYTE))
1152                         *p-- = 0;
1153         }
1154         /* clear msb bits if any leftover in the last byte */
1155         *p &= GENMASK((cell->nbits%BITS_PER_BYTE) - 1, 0);
1156 }
1157
1158 static int __nvmem_cell_read(struct nvmem_device *nvmem,
1159                       struct nvmem_cell *cell,
1160                       void *buf, size_t *len)
1161 {
1162         int rc;
1163
1164         rc = nvmem_reg_read(nvmem, cell->offset, buf, cell->bytes);
1165
1166         if (rc)
1167                 return rc;
1168
1169         /* shift bits in-place */
1170         if (cell->bit_offset || cell->nbits)
1171                 nvmem_shift_read_buffer_in_place(cell, buf);
1172
1173         if (len)
1174                 *len = cell->bytes;
1175
1176         return 0;
1177 }
1178
1179 /**
1180  * nvmem_cell_read() - Read a given nvmem cell
1181  *
1182  * @cell: nvmem cell to be read.
1183  * @len: pointer to length of cell which will be populated on successful read;
1184  *       can be NULL.
1185  *
1186  * Return: ERR_PTR() on error or a valid pointer to a buffer on success. The
1187  * buffer should be freed by the consumer with a kfree().
1188  */
1189 void *nvmem_cell_read(struct nvmem_cell *cell, size_t *len)
1190 {
1191         struct nvmem_device *nvmem = cell->nvmem;
1192         u8 *buf;
1193         int rc;
1194
1195         if (!nvmem)
1196                 return ERR_PTR(-EINVAL);
1197
1198         buf = kzalloc(cell->bytes, GFP_KERNEL);
1199         if (!buf)
1200                 return ERR_PTR(-ENOMEM);
1201
1202         rc = __nvmem_cell_read(nvmem, cell, buf, len);
1203         if (rc) {
1204                 kfree(buf);
1205                 return ERR_PTR(rc);
1206         }
1207
1208         return buf;
1209 }
1210 EXPORT_SYMBOL_GPL(nvmem_cell_read);
1211
1212 static void *nvmem_cell_prepare_write_buffer(struct nvmem_cell *cell,
1213                                              u8 *_buf, int len)
1214 {
1215         struct nvmem_device *nvmem = cell->nvmem;
1216         int i, rc, nbits, bit_offset = cell->bit_offset;
1217         u8 v, *p, *buf, *b, pbyte, pbits;
1218
1219         nbits = cell->nbits;
1220         buf = kzalloc(cell->bytes, GFP_KERNEL);
1221         if (!buf)
1222                 return ERR_PTR(-ENOMEM);
1223
1224         memcpy(buf, _buf, len);
1225         p = b = buf;
1226
1227         if (bit_offset) {
1228                 pbyte = *b;
1229                 *b <<= bit_offset;
1230
1231                 /* setup the first byte with lsb bits from nvmem */
1232                 rc = nvmem_reg_read(nvmem, cell->offset, &v, 1);
1233                 if (rc)
1234                         goto err;
1235                 *b++ |= GENMASK(bit_offset - 1, 0) & v;
1236
1237                 /* setup rest of the byte if any */
1238                 for (i = 1; i < cell->bytes; i++) {
1239                         /* Get last byte bits and shift them towards lsb */
1240                         pbits = pbyte >> (BITS_PER_BYTE - 1 - bit_offset);
1241                         pbyte = *b;
1242                         p = b;
1243                         *b <<= bit_offset;
1244                         *b++ |= pbits;
1245                 }
1246         }
1247
1248         /* if it's not end on byte boundary */
1249         if ((nbits + bit_offset) % BITS_PER_BYTE) {
1250                 /* setup the last byte with msb bits from nvmem */
1251                 rc = nvmem_reg_read(nvmem,
1252                                     cell->offset + cell->bytes - 1, &v, 1);
1253                 if (rc)
1254                         goto err;
1255                 *p |= GENMASK(7, (nbits + bit_offset) % BITS_PER_BYTE) & v;
1256
1257         }
1258
1259         return buf;
1260 err:
1261         kfree(buf);
1262         return ERR_PTR(rc);
1263 }
1264
1265 /**
1266  * nvmem_cell_write() - Write to a given nvmem cell
1267  *
1268  * @cell: nvmem cell to be written.
1269  * @buf: Buffer to be written.
1270  * @len: length of buffer to be written to nvmem cell.
1271  *
1272  * Return: length of bytes written or negative on failure.
1273  */
1274 int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len)
1275 {
1276         struct nvmem_device *nvmem = cell->nvmem;
1277         int rc;
1278
1279         if (!nvmem || nvmem->read_only ||
1280             (cell->bit_offset == 0 && len != cell->bytes))
1281                 return -EINVAL;
1282
1283         if (cell->bit_offset || cell->nbits) {
1284                 buf = nvmem_cell_prepare_write_buffer(cell, buf, len);
1285                 if (IS_ERR(buf))
1286                         return PTR_ERR(buf);
1287         }
1288
1289         rc = nvmem_reg_write(nvmem, cell->offset, buf, cell->bytes);
1290
1291         /* free the tmp buffer */
1292         if (cell->bit_offset || cell->nbits)
1293                 kfree(buf);
1294
1295         if (rc)
1296                 return rc;
1297
1298         return len;
1299 }
1300 EXPORT_SYMBOL_GPL(nvmem_cell_write);
1301
1302 /**
1303  * nvmem_cell_read_u32() - Read a cell value as an u32
1304  *
1305  * @dev: Device that requests the nvmem cell.
1306  * @cell_id: Name of nvmem cell to read.
1307  * @val: pointer to output value.
1308  *
1309  * Return: 0 on success or negative errno.
1310  */
1311 int nvmem_cell_read_u32(struct device *dev, const char *cell_id, u32 *val)
1312 {
1313         struct nvmem_cell *cell;
1314         void *buf;
1315         size_t len;
1316
1317         cell = nvmem_cell_get(dev, cell_id);
1318         if (IS_ERR(cell))
1319                 return PTR_ERR(cell);
1320
1321         buf = nvmem_cell_read(cell, &len);
1322         if (IS_ERR(buf)) {
1323                 nvmem_cell_put(cell);
1324                 return PTR_ERR(buf);
1325         }
1326         if (len != sizeof(*val)) {
1327                 kfree(buf);
1328                 nvmem_cell_put(cell);
1329                 return -EINVAL;
1330         }
1331         memcpy(val, buf, sizeof(*val));
1332
1333         kfree(buf);
1334         nvmem_cell_put(cell);
1335         return 0;
1336 }
1337 EXPORT_SYMBOL_GPL(nvmem_cell_read_u32);
1338
1339 /**
1340  * nvmem_device_cell_read() - Read a given nvmem device and cell
1341  *
1342  * @nvmem: nvmem device to read from.
1343  * @info: nvmem cell info to be read.
1344  * @buf: buffer pointer which will be populated on successful read.
1345  *
1346  * Return: length of successful bytes read on success and negative
1347  * error code on error.
1348  */
1349 ssize_t nvmem_device_cell_read(struct nvmem_device *nvmem,
1350                            struct nvmem_cell_info *info, void *buf)
1351 {
1352         struct nvmem_cell cell;
1353         int rc;
1354         ssize_t len;
1355
1356         if (!nvmem)
1357                 return -EINVAL;
1358
1359         rc = nvmem_cell_info_to_nvmem_cell(nvmem, info, &cell);
1360         if (rc)
1361                 return rc;
1362
1363         rc = __nvmem_cell_read(nvmem, &cell, buf, &len);
1364         if (rc)
1365                 return rc;
1366
1367         return len;
1368 }
1369 EXPORT_SYMBOL_GPL(nvmem_device_cell_read);
1370
1371 /**
1372  * nvmem_device_cell_write() - Write cell to a given nvmem device
1373  *
1374  * @nvmem: nvmem device to be written to.
1375  * @info: nvmem cell info to be written.
1376  * @buf: buffer to be written to cell.
1377  *
1378  * Return: length of bytes written or negative error code on failure.
1379  */
1380 int nvmem_device_cell_write(struct nvmem_device *nvmem,
1381                             struct nvmem_cell_info *info, void *buf)
1382 {
1383         struct nvmem_cell cell;
1384         int rc;
1385
1386         if (!nvmem)
1387                 return -EINVAL;
1388
1389         rc = nvmem_cell_info_to_nvmem_cell(nvmem, info, &cell);
1390         if (rc)
1391                 return rc;
1392
1393         return nvmem_cell_write(&cell, buf, cell.bytes);
1394 }
1395 EXPORT_SYMBOL_GPL(nvmem_device_cell_write);
1396
1397 /**
1398  * nvmem_device_read() - Read from a given nvmem device
1399  *
1400  * @nvmem: nvmem device to read from.
1401  * @offset: offset in nvmem device.
1402  * @bytes: number of bytes to read.
1403  * @buf: buffer pointer which will be populated on successful read.
1404  *
1405  * Return: length of successful bytes read on success and negative
1406  * error code on error.
1407  */
1408 int nvmem_device_read(struct nvmem_device *nvmem,
1409                       unsigned int offset,
1410                       size_t bytes, void *buf)
1411 {
1412         int rc;
1413
1414         if (!nvmem)
1415                 return -EINVAL;
1416
1417         rc = nvmem_reg_read(nvmem, offset, buf, bytes);
1418
1419         if (rc)
1420                 return rc;
1421
1422         return bytes;
1423 }
1424 EXPORT_SYMBOL_GPL(nvmem_device_read);
1425
1426 /**
1427  * nvmem_device_write() - Write cell to a given nvmem device
1428  *
1429  * @nvmem: nvmem device to be written to.
1430  * @offset: offset in nvmem device.
1431  * @bytes: number of bytes to write.
1432  * @buf: buffer to be written.
1433  *
1434  * Return: length of bytes written or negative error code on failure.
1435  */
1436 int nvmem_device_write(struct nvmem_device *nvmem,
1437                        unsigned int offset,
1438                        size_t bytes, void *buf)
1439 {
1440         int rc;
1441
1442         if (!nvmem)
1443                 return -EINVAL;
1444
1445         rc = nvmem_reg_write(nvmem, offset, buf, bytes);
1446
1447         if (rc)
1448                 return rc;
1449
1450
1451         return bytes;
1452 }
1453 EXPORT_SYMBOL_GPL(nvmem_device_write);
1454
1455 /**
1456  * nvmem_add_cell_table() - register a table of cell info entries
1457  *
1458  * @table: table of cell info entries
1459  */
1460 void nvmem_add_cell_table(struct nvmem_cell_table *table)
1461 {
1462         mutex_lock(&nvmem_cell_mutex);
1463         list_add_tail(&table->node, &nvmem_cell_tables);
1464         mutex_unlock(&nvmem_cell_mutex);
1465 }
1466 EXPORT_SYMBOL_GPL(nvmem_add_cell_table);
1467
1468 /**
1469  * nvmem_del_cell_table() - remove a previously registered cell info table
1470  *
1471  * @table: table of cell info entries
1472  */
1473 void nvmem_del_cell_table(struct nvmem_cell_table *table)
1474 {
1475         mutex_lock(&nvmem_cell_mutex);
1476         list_del(&table->node);
1477         mutex_unlock(&nvmem_cell_mutex);
1478 }
1479 EXPORT_SYMBOL_GPL(nvmem_del_cell_table);
1480
1481 /**
1482  * nvmem_add_cell_lookups() - register a list of cell lookup entries
1483  *
1484  * @entries: array of cell lookup entries
1485  * @nentries: number of cell lookup entries in the array
1486  */
1487 void nvmem_add_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
1488 {
1489         int i;
1490
1491         mutex_lock(&nvmem_lookup_mutex);
1492         for (i = 0; i < nentries; i++)
1493                 list_add_tail(&entries[i].node, &nvmem_lookup_list);
1494         mutex_unlock(&nvmem_lookup_mutex);
1495 }
1496 EXPORT_SYMBOL_GPL(nvmem_add_cell_lookups);
1497
1498 /**
1499  * nvmem_del_cell_lookups() - remove a list of previously added cell lookup
1500  *                            entries
1501  *
1502  * @entries: array of cell lookup entries
1503  * @nentries: number of cell lookup entries in the array
1504  */
1505 void nvmem_del_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
1506 {
1507         int i;
1508
1509         mutex_lock(&nvmem_lookup_mutex);
1510         for (i = 0; i < nentries; i++)
1511                 list_del(&entries[i].node);
1512         mutex_unlock(&nvmem_lookup_mutex);
1513 }
1514 EXPORT_SYMBOL_GPL(nvmem_del_cell_lookups);
1515
1516 /**
1517  * nvmem_dev_name() - Get the name of a given nvmem device.
1518  *
1519  * @nvmem: nvmem device.
1520  *
1521  * Return: name of the nvmem device.
1522  */
1523 const char *nvmem_dev_name(struct nvmem_device *nvmem)
1524 {
1525         return dev_name(&nvmem->dev);
1526 }
1527 EXPORT_SYMBOL_GPL(nvmem_dev_name);
1528
1529 static int __init nvmem_init(void)
1530 {
1531         return bus_register(&nvmem_bus_type);
1532 }
1533
1534 static void __exit nvmem_exit(void)
1535 {
1536         bus_unregister(&nvmem_bus_type);
1537 }
1538
1539 subsys_initcall(nvmem_init);
1540 module_exit(nvmem_exit);
1541
1542 MODULE_AUTHOR("Srinivas Kandagatla <[email protected]");
1543 MODULE_AUTHOR("Maxime Ripard <[email protected]");
1544 MODULE_DESCRIPTION("nvmem Driver Core");
1545 MODULE_LICENSE("GPL v2");