drivers/nvmem/core.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * nvmem framework core.
   4  *
   5  * Copyright (C) 2015 Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
   6  * Copyright (C) 2013 Maxime Ripard <maxime.ripard@free-electrons.com>
   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         enum nvmem_type         type;
  32         struct bin_attribute    eeprom;
  33         struct device           *base_dev;
  34         struct list_head        cells;
  35         nvmem_reg_read_t        reg_read;
  36         nvmem_reg_write_t       reg_write;
  37         void *priv;
  38 };
  39
  40 #define FLAG_COMPAT             BIT(0)
  41
  42 struct nvmem_cell {
  43         const char              *name;
  44         int                     offset;
  45         int                     bytes;
  46         int                     bit_offset;
  47         int                     nbits;
  48         struct device_node      *np;
  49         struct nvmem_device     *nvmem;
  50         struct list_head        node;
  51 };
  52
  53 static DEFINE_MUTEX(nvmem_mutex);
  54 static DEFINE_IDA(nvmem_ida);
  55
  56 static DEFINE_MUTEX(nvmem_cell_mutex);
  57 static LIST_HEAD(nvmem_cell_tables);
  58
  59 static DEFINE_MUTEX(nvmem_lookup_mutex);
  60 static LIST_HEAD(nvmem_lookup_list);
  61
  62 static BLOCKING_NOTIFIER_HEAD(nvmem_notifier);
  63
  64 static const char * const nvmem_type_str[] = {
  65         [NVMEM_TYPE_UNKNOWN] = "Unknown",
  66         [NVMEM_TYPE_EEPROM] = "EEPROM",
  67         [NVMEM_TYPE_OTP] = "OTP",
  68         [NVMEM_TYPE_BATTERY_BACKED] = "Battery backed",
  69 };
  70
  71 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  72 static struct lock_class_key eeprom_lock_key;
  73 #endif
  74
  75 #define to_nvmem_device(d) container_of(d, struct nvmem_device, dev)
  76 static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
  77                           void *val, size_t bytes)
  78 {
  79         if (nvmem->reg_read)
  80                 return nvmem->reg_read(nvmem->priv, offset, val, bytes);
  81
  82         return -EINVAL;
  83 }
  84
  85 static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
  86                            void *val, size_t bytes)
  87 {
  88         if (nvmem->reg_write)
  89                 return nvmem->reg_write(nvmem->priv, offset, val, bytes);
  90
  91         return -EINVAL;
  92 }
  93
  94 static ssize_t type_show(struct device *dev,
  95                          struct device_attribute *attr, char *buf)
  96 {
  97         struct nvmem_device *nvmem = to_nvmem_device(dev);
  98
  99         return sprintf(buf, "%s\n", nvmem_type_str[nvmem->type]);
 100 }
 101
 102 static DEVICE_ATTR_RO(type);
 103
 104 static struct attribute *nvmem_attrs[] = {
 105         &dev_attr_type.attr,
 106         NULL,
 107 };
 108
 109 static ssize_t bin_attr_nvmem_read(struct file *filp, struct kobject *kobj,
 110                                     struct bin_attribute *attr,
 111                                     char *buf, loff_t pos, size_t count)
 112 {
 113         struct device *dev;
 114         struct nvmem_device *nvmem;
 115         int rc;
 116
 117         if (attr->private)
 118                 dev = attr->private;
 119         else
 120                 dev = container_of(kobj, struct device, kobj);
 121         nvmem = to_nvmem_device(dev);
 122
 123         /* Stop the user from reading */
 124         if (pos >= nvmem->size)
 125                 return 0;
 126
 127         if (count < nvmem->word_size)
 128                 return -EINVAL;
 129
 130         if (pos + count > nvmem->size)
 131                 count = nvmem->size - pos;
 132
 133         count = round_down(count, nvmem->word_size);
 134
 135         rc = nvmem_reg_read(nvmem, pos, buf, count);
 136
 137         if (rc)
 138                 return rc;
 139
 140         return count;
 141 }
 142
 143 static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj,
 144                                      struct bin_attribute *attr,
 145                                      char *buf, loff_t pos, size_t count)
 146 {
 147         struct device *dev;
 148         struct nvmem_device *nvmem;
 149         int rc;
 150
 151         if (attr->private)
 152                 dev = attr->private;
 153         else
 154                 dev = container_of(kobj, struct device, kobj);
 155         nvmem = to_nvmem_device(dev);
 156
 157         /* Stop the user from writing */
 158         if (pos >= nvmem->size)
 159                 return -EFBIG;
 160
 161         if (count < nvmem->word_size)
 162                 return -EINVAL;
 163
 164         if (pos + count > nvmem->size)
 165                 count = nvmem->size - pos;
 166
 167         count = round_down(count, nvmem->word_size);
 168
 169         rc = nvmem_reg_write(nvmem, pos, buf, count);
 170
 171         if (rc)
 172                 return rc;
 173
 174         return count;
 175 }
 176
 177 /* default read/write permissions */
 178 static struct bin_attribute bin_attr_rw_nvmem = {
 179         .attr   = {
 180                 .name   = "nvmem",
 181                 .mode   = 0644,
 182         },
 183         .read   = bin_attr_nvmem_read,
 184         .write  = bin_attr_nvmem_write,
 185 };
 186
 187 static struct bin_attribute *nvmem_bin_rw_attributes[] = {
 188         &bin_attr_rw_nvmem,
 189         NULL,
 190 };
 191
 192 static const struct attribute_group nvmem_bin_rw_group = {
 193         .bin_attrs      = nvmem_bin_rw_attributes,
 194         .attrs          = nvmem_attrs,
 195 };
 196
 197 static const struct attribute_group *nvmem_rw_dev_groups[] = {
 198         &nvmem_bin_rw_group,
 199         NULL,
 200 };
 201
 202 /* read only permission */
 203 static struct bin_attribute bin_attr_ro_nvmem = {
 204         .attr   = {
 205                 .name   = "nvmem",
 206                 .mode   = 0444,
 207         },
 208         .read   = bin_attr_nvmem_read,
 209 };
 210
 211 static struct bin_attribute *nvmem_bin_ro_attributes[] = {
 212         &bin_attr_ro_nvmem,
 213         NULL,
 214 };
 215
 216 static const struct attribute_group nvmem_bin_ro_group = {
 217         .bin_attrs      = nvmem_bin_ro_attributes,
 218         .attrs          = nvmem_attrs,
 219 };
 220
 221 static const struct attribute_group *nvmem_ro_dev_groups[] = {
 222         &nvmem_bin_ro_group,
 223         NULL,
 224 };
 225
 226 /* default read/write permissions, root only */
 227 static struct bin_attribute bin_attr_rw_root_nvmem = {
 228         .attr   = {
 229                 .name   = "nvmem",
 230                 .mode   = 0600,
 231         },
 232         .read   = bin_attr_nvmem_read,
 233         .write  = bin_attr_nvmem_write,
 234 };
 235
 236 static struct bin_attribute *nvmem_bin_rw_root_attributes[] = {
 237         &bin_attr_rw_root_nvmem,
 238         NULL,
 239 };
 240
 241 static const struct attribute_group nvmem_bin_rw_root_group = {
 242         .bin_attrs      = nvmem_bin_rw_root_attributes,
 243         .attrs          = nvmem_attrs,
 244 };
 245
 246 static const struct attribute_group *nvmem_rw_root_dev_groups[] = {
 247         &nvmem_bin_rw_root_group,
 248         NULL,
 249 };
 250
 251 /* read only permission, root only */
 252 static struct bin_attribute bin_attr_ro_root_nvmem = {
 253         .attr   = {
 254                 .name   = "nvmem",
 255                 .mode   = 0400,
 256         },
 257         .read   = bin_attr_nvmem_read,
 258 };
 259
 260 static struct bin_attribute *nvmem_bin_ro_root_attributes[] = {
 261         &bin_attr_ro_root_nvmem,
 262         NULL,
 263 };
 264
 265 static const struct attribute_group nvmem_bin_ro_root_group = {
 266         .bin_attrs      = nvmem_bin_ro_root_attributes,
 267         .attrs          = nvmem_attrs,
 268 };
 269
 270 static const struct attribute_group *nvmem_ro_root_dev_groups[] = {
 271         &nvmem_bin_ro_root_group,
 272         NULL,
 273 };
 274
 275 static void nvmem_release(struct device *dev)
 276 {
 277         struct nvmem_device *nvmem = to_nvmem_device(dev);
 278
 279         ida_simple_remove(&nvmem_ida, nvmem->id);
 280         kfree(nvmem);
 281 }
 282
 283 static const struct device_type nvmem_provider_type = {
 284         .release        = nvmem_release,
 285 };
 286
 287 static struct bus_type nvmem_bus_type = {
 288         .name           = "nvmem",
 289 };
 290
 291 static int of_nvmem_match(struct device *dev, void *nvmem_np)
 292 {
 293         return dev->of_node == nvmem_np;
 294 }
 295
 296 static struct nvmem_device *of_nvmem_find(struct device_node *nvmem_np)
 297 {
 298         struct device *d;
 299
 300         if (!nvmem_np)
 301                 return NULL;
 302
 303         d = bus_find_device(&nvmem_bus_type, NULL, nvmem_np, of_nvmem_match);
 304
 305         if (!d)
 306                 return NULL;
 307
 308         return to_nvmem_device(d);
 309 }
 310
 311 static struct nvmem_device *nvmem_find(const char *name)
 312 {
 313         struct device *d;
 314
 315         d = bus_find_device_by_name(&nvmem_bus_type, NULL, name);
 316
 317         if (!d)
 318                 return NULL;
 319
 320         return to_nvmem_device(d);
 321 }
 322
 323 static void nvmem_cell_drop(struct nvmem_cell *cell)
 324 {
 325         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_REMOVE, cell);
 326         mutex_lock(&nvmem_mutex);
 327         list_del(&cell->node);
 328         mutex_unlock(&nvmem_mutex);
 329         of_node_put(cell->np);
 330         kfree(cell->name);
 331         kfree(cell);
 332 }
 333
 334 static void nvmem_device_remove_all_cells(const struct nvmem_device *nvmem)
 335 {
 336         struct nvmem_cell *cell, *p;
 337
 338         list_for_each_entry_safe(cell, p, &nvmem->cells, node)
 339                 nvmem_cell_drop(cell);
 340 }
 341
 342 static void nvmem_cell_add(struct nvmem_cell *cell)
 343 {
 344         mutex_lock(&nvmem_mutex);
 345         list_add_tail(&cell->node, &cell->nvmem->cells);
 346         mutex_unlock(&nvmem_mutex);
 347         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_ADD, cell);
 348 }
 349
 350 static int nvmem_cell_info_to_nvmem_cell(struct nvmem_device *nvmem,
 351                                    const struct nvmem_cell_info *info,
 352                                    struct nvmem_cell *cell)
 353 {
 354         cell->nvmem = nvmem;
 355         cell->offset = info->offset;
 356         cell->bytes = info->bytes;
 357         cell->name = info->name;
 358
 359         cell->bit_offset = info->bit_offset;
 360         cell->nbits = info->nbits;
 361
 362         if (cell->nbits)
 363                 cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
 364                                            BITS_PER_BYTE);
 365
 366         if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
 367                 dev_err(&nvmem->dev,
 368                         "cell %s unaligned to nvmem stride %d\n",
 369                         cell->name, nvmem->stride);
 370                 return -EINVAL;
 371         }
 372
 373         return 0;
 374 }
 375
 376 /**
 377  * nvmem_add_cells() - Add cell information to an nvmem device
 378  *
 379  * @nvmem: nvmem device to add cells to.
 380  * @info: nvmem cell info to add to the device
 381  * @ncells: number of cells in info
 382  *
 383  * Return: 0 or negative error code on failure.
 384  */
 385 static int nvmem_add_cells(struct nvmem_device *nvmem,
 386                     const struct nvmem_cell_info *info,
 387                     int ncells)
 388 {
 389         struct nvmem_cell **cells;
 390         int i, rval;
 391
 392         cells = kcalloc(ncells, sizeof(*cells), GFP_KERNEL);
 393         if (!cells)
 394                 return -ENOMEM;
 395
 396         for (i = 0; i < ncells; i++) {
 397                 cells[i] = kzalloc(sizeof(**cells), GFP_KERNEL);
 398                 if (!cells[i]) {
 399                         rval = -ENOMEM;
 400                         goto err;
 401                 }
 402
 403                 rval = nvmem_cell_info_to_nvmem_cell(nvmem, &info[i], cells[i]);
 404                 if (rval) {
 405                         kfree(cells[i]);
 406                         goto err;
 407                 }
 408
 409                 nvmem_cell_add(cells[i]);
 410         }
 411
 412         /* remove tmp array */
 413         kfree(cells);
 414
 415         return 0;
 416 err:
 417         while (i--)
 418                 nvmem_cell_drop(cells[i]);
 419
 420         kfree(cells);
 421
 422         return rval;
 423 }
 424
 425 /*
 426  * nvmem_setup_compat() - Create an additional binary entry in
 427  * drivers sys directory, to be backwards compatible with the older
 428  * drivers/misc/eeprom drivers.
 429  */
 430 static int nvmem_setup_compat(struct nvmem_device *nvmem,
 431                               const struct nvmem_config *config)
 432 {
 433         int rval;
 434
 435         if (!config->base_dev)
 436                 return -EINVAL;
 437
 438         if (nvmem->read_only)
 439                 nvmem->eeprom = bin_attr_ro_root_nvmem;
 440         else
 441                 nvmem->eeprom = bin_attr_rw_root_nvmem;
 442         nvmem->eeprom.attr.name = "eeprom";
 443         nvmem->eeprom.size = nvmem->size;
 444 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 445         nvmem->eeprom.attr.key = &eeprom_lock_key;
 446 #endif
 447         nvmem->eeprom.private = &nvmem->dev;
 448         nvmem->base_dev = config->base_dev;
 449
 450         rval = device_create_bin_file(nvmem->base_dev, &nvmem->eeprom);
 451         if (rval) {
 452                 dev_err(&nvmem->dev,
 453                         "Failed to create eeprom binary file %d\n", rval);
 454                 return rval;
 455         }
 456
 457         nvmem->flags |= FLAG_COMPAT;
 458
 459         return 0;
 460 }
 461
 462 /**
 463  * nvmem_register_notifier() - Register a notifier block for nvmem events.
 464  *
 465  * @nb: notifier block to be called on nvmem events.
 466  *
 467  * Return: 0 on success, negative error number on failure.
 468  */
 469 int nvmem_register_notifier(struct notifier_block *nb)
 470 {
 471         return blocking_notifier_chain_register(&nvmem_notifier, nb);
 472 }
 473 EXPORT_SYMBOL_GPL(nvmem_register_notifier);
 474
 475 /**
 476  * nvmem_unregister_notifier() - Unregister a notifier block for nvmem events.
 477  *
 478  * @nb: notifier block to be unregistered.
 479  *
 480  * Return: 0 on success, negative error number on failure.
 481  */
 482 int nvmem_unregister_notifier(struct notifier_block *nb)
 483 {
 484         return blocking_notifier_chain_unregister(&nvmem_notifier, nb);
 485 }
 486 EXPORT_SYMBOL_GPL(nvmem_unregister_notifier);
 487
 488 static int nvmem_add_cells_from_table(struct nvmem_device *nvmem)
 489 {
 490         const struct nvmem_cell_info *info;
 491         struct nvmem_cell_table *table;
 492         struct nvmem_cell *cell;
 493         int rval = 0, i;
 494
 495         mutex_lock(&nvmem_cell_mutex);
 496         list_for_each_entry(table, &nvmem_cell_tables, node) {
 497                 if (strcmp(nvmem_dev_name(nvmem), table->nvmem_name) == 0) {
 498                         for (i = 0; i < table->ncells; i++) {
 499                                 info = &table->cells[i];
 500
 501                                 cell = kzalloc(sizeof(*cell), GFP_KERNEL);
 502                                 if (!cell) {
 503                                         rval = -ENOMEM;
 504                                         goto out;
 505                                 }
 506
 507                                 rval = nvmem_cell_info_to_nvmem_cell(nvmem,
 508                                                                      info,
 509                                                                      cell);
 510                                 if (rval) {
 511                                         kfree(cell);
 512                                         goto out;
 513                                 }
 514
 515                                 nvmem_cell_add(cell);
 516                         }
 517                 }
 518         }
 519
 520 out:
 521         mutex_unlock(&nvmem_cell_mutex);
 522         return rval;
 523 }
 524
 525 static struct nvmem_cell *
 526 nvmem_find_cell_by_name(struct nvmem_device *nvmem, const char *cell_id)
 527 {
 528         struct nvmem_cell *iter, *cell = NULL;
 529
 530         mutex_lock(&nvmem_mutex);
 531         list_for_each_entry(iter, &nvmem->cells, node) {
 532                 if (strcmp(cell_id, iter->name) == 0) {
 533                         cell = iter;
 534                         break;
 535                 }
 536         }
 537         mutex_unlock(&nvmem_mutex);
 538
 539         return cell;
 540 }
 541
 542 static int nvmem_add_cells_from_of(struct nvmem_device *nvmem)
 543 {
 544         struct device_node *parent, *child;
 545         struct device *dev = &nvmem->dev;
 546         struct nvmem_cell *cell;
 547         const __be32 *addr;
 548         int len;
 549
 550         parent = dev->of_node;
 551
 552         for_each_child_of_node(parent, child) {
 553                 addr = of_get_property(child, "reg", &len);
 554                 if (!addr || (len < 2 * sizeof(u32))) {
 555                         dev_err(dev, "nvmem: invalid reg on %pOF\n", child);
 556                         return -EINVAL;
 557                 }
 558
 559                 cell = kzalloc(sizeof(*cell), GFP_KERNEL);
 560                 if (!cell)
 561                         return -ENOMEM;
 562
 563                 cell->nvmem = nvmem;
 564                 cell->np = of_node_get(child);
 565                 cell->offset = be32_to_cpup(addr++);
 566                 cell->bytes = be32_to_cpup(addr);
 567                 cell->name = kasprintf(GFP_KERNEL, "%pOFn", child);
 568
 569                 addr = of_get_property(child, "bits", &len);
 570                 if (addr && len == (2 * sizeof(u32))) {
 571                         cell->bit_offset = be32_to_cpup(addr++);
 572                         cell->nbits = be32_to_cpup(addr);
 573                 }
 574
 575                 if (cell->nbits)
 576                         cell->bytes = DIV_ROUND_UP(
 577                                         cell->nbits + cell->bit_offset,
 578                                         BITS_PER_BYTE);
 579
 580                 if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
 581                         dev_err(dev, "cell %s unaligned to nvmem stride %d\n",
 582                                 cell->name, nvmem->stride);
 583                         /* Cells already added will be freed later. */
 584                         kfree(cell->name);
 585                         kfree(cell);
 586                         return -EINVAL;
 587                 }
 588
 589                 nvmem_cell_add(cell);
 590         }
 591
 592         return 0;
 593 }
 594
 595 /**
 596  * nvmem_register() - Register a nvmem device for given nvmem_config.
 597  * Also creates an binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
 598  *
 599  * @config: nvmem device configuration with which nvmem device is created.
 600  *
 601  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
 602  * on success.
 603  */
 604
 605 struct nvmem_device *nvmem_register(const struct nvmem_config *config)
 606 {
 607         struct nvmem_device *nvmem;
 608         int rval;
 609
 610         if (!config->dev)
 611                 return ERR_PTR(-EINVAL);
 612
 613         nvmem = kzalloc(sizeof(*nvmem), GFP_KERNEL);
 614         if (!nvmem)
 615                 return ERR_PTR(-ENOMEM);
 616
 617         rval  = ida_simple_get(&nvmem_ida, 0, 0, GFP_KERNEL);
 618         if (rval < 0) {
 619                 kfree(nvmem);
 620                 return ERR_PTR(rval);
 621         }
 622
 623         kref_init(&nvmem->refcnt);
 624         INIT_LIST_HEAD(&nvmem->cells);
 625
 626         nvmem->id = rval;
 627         nvmem->owner = config->owner;
 628         if (!nvmem->owner && config->dev->driver)
 629                 nvmem->owner = config->dev->driver->owner;
 630         nvmem->stride = config->stride ?: 1;
 631         nvmem->word_size = config->word_size ?: 1;
 632         nvmem->size = config->size;
 633         nvmem->dev.type = &nvmem_provider_type;
 634         nvmem->dev.bus = &nvmem_bus_type;
 635         nvmem->dev.parent = config->dev;
 636         nvmem->priv = config->priv;
 637         nvmem->type = config->type;
 638         nvmem->reg_read = config->reg_read;
 639         nvmem->reg_write = config->reg_write;
 640         if (!config->no_of_node)
 641                 nvmem->dev.of_node = config->dev->of_node;
 642
 643         if (config->id == -1 && config->name) {
 644                 dev_set_name(&nvmem->dev, "%s", config->name);
 645         } else {
 646                 dev_set_name(&nvmem->dev, "%s%d",
 647                              config->name ? : "nvmem",
 648                              config->name ? config->id : nvmem->id);
 649         }
 650
 651         nvmem->read_only = device_property_present(config->dev, "read-only") ||
 652                            config->read_only || !nvmem->reg_write;
 653
 654         if (config->root_only)
 655                 nvmem->dev.groups = nvmem->read_only ?
 656                         nvmem_ro_root_dev_groups :
 657                         nvmem_rw_root_dev_groups;
 658         else
 659                 nvmem->dev.groups = nvmem->read_only ?
 660                         nvmem_ro_dev_groups :
 661                         nvmem_rw_dev_groups;
 662
 663         device_initialize(&nvmem->dev);
 664
 665         dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
 666
 667         rval = device_add(&nvmem->dev);
 668         if (rval)
 669                 goto err_put_device;
 670
 671         if (config->compat) {
 672                 rval = nvmem_setup_compat(nvmem, config);
 673                 if (rval)
 674                         goto err_device_del;
 675         }
 676
 677         if (config->cells) {
 678                 rval = nvmem_add_cells(nvmem, config->cells, config->ncells);
 679                 if (rval)
 680                         goto err_teardown_compat;
 681         }
 682
 683         rval = nvmem_add_cells_from_table(nvmem);
 684         if (rval)
 685                 goto err_remove_cells;
 686
 687         rval = nvmem_add_cells_from_of(nvmem);
 688         if (rval)
 689                 goto err_remove_cells;
 690
 691         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem);
 692
 693         return nvmem;
 694
 695 err_remove_cells:
 696         nvmem_device_remove_all_cells(nvmem);
 697 err_teardown_compat:
 698         if (config->compat)
 699                 device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
 700 err_device_del:
 701         device_del(&nvmem->dev);
 702 err_put_device:
 703         put_device(&nvmem->dev);
 704
 705         return ERR_PTR(rval);
 706 }
 707 EXPORT_SYMBOL_GPL(nvmem_register);
 708
 709 static void nvmem_device_release(struct kref *kref)
 710 {
 711         struct nvmem_device *nvmem;
 712
 713         nvmem = container_of(kref, struct nvmem_device, refcnt);
 714
 715         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_REMOVE, nvmem);
 716
 717         if (nvmem->flags & FLAG_COMPAT)
 718                 device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
 719
 720         nvmem_device_remove_all_cells(nvmem);
 721         device_del(&nvmem->dev);
 722         put_device(&nvmem->dev);
 723 }
 724
 725 /**
 726  * nvmem_unregister() - Unregister previously registered nvmem device
 727  *
 728  * @nvmem: Pointer to previously registered nvmem device.
 729  */
 730 void nvmem_unregister(struct nvmem_device *nvmem)
 731 {
 732         kref_put(&nvmem->refcnt, nvmem_device_release);
 733 }
 734 EXPORT_SYMBOL_GPL(nvmem_unregister);
 735
 736 static void devm_nvmem_release(struct device *dev, void *res)
 737 {
 738         nvmem_unregister(*(struct nvmem_device **)res);
 739 }
 740
 741 /**
 742  * devm_nvmem_register() - Register a managed nvmem device for given
 743  * nvmem_config.
 744  * Also creates an binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
 745  *
 746  * @dev: Device that uses the nvmem device.
 747  * @config: nvmem device configuration with which nvmem device is created.
 748  *
 749  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
 750  * on success.
 751  */
 752 struct nvmem_device *devm_nvmem_register(struct device *dev,
 753                                          const struct nvmem_config *config)
 754 {
 755         struct nvmem_device **ptr, *nvmem;
 756
 757         ptr = devres_alloc(devm_nvmem_release, sizeof(*ptr), GFP_KERNEL);
 758         if (!ptr)
 759                 return ERR_PTR(-ENOMEM);
 760
 761         nvmem = nvmem_register(config);
 762
 763         if (!IS_ERR(nvmem)) {
 764                 *ptr = nvmem;
 765                 devres_add(dev, ptr);
 766         } else {
 767                 devres_free(ptr);
 768         }
 769
 770         return nvmem;
 771 }
 772 EXPORT_SYMBOL_GPL(devm_nvmem_register);
 773
 774 static int devm_nvmem_match(struct device *dev, void *res, void *data)
 775 {
 776         struct nvmem_device **r = res;
 777
 778         return *r == data;
 779 }
 780
 781 /**
 782  * devm_nvmem_unregister() - Unregister previously registered managed nvmem
 783  * device.
 784  *
 785  * @dev: Device that uses the nvmem device.
 786  * @nvmem: Pointer to previously registered nvmem device.
 787  *
 788  * Return: Will be an negative on error or a zero on success.
 789  */
 790 int devm_nvmem_unregister(struct device *dev, struct nvmem_device *nvmem)
 791 {
 792         return devres_release(dev, devm_nvmem_release, devm_nvmem_match, nvmem);
 793 }
 794 EXPORT_SYMBOL(devm_nvmem_unregister);
 795
 796 static struct nvmem_device *__nvmem_device_get(struct device_node *np,
 797                                                const char *nvmem_name)
 798 {
 799         struct nvmem_device *nvmem = NULL;
 800
 801         mutex_lock(&nvmem_mutex);
 802         nvmem = np ? of_nvmem_find(np) : nvmem_find(nvmem_name);
 803         mutex_unlock(&nvmem_mutex);
 804         if (!nvmem)
 805                 return ERR_PTR(-EPROBE_DEFER);
 806
 807         if (!try_module_get(nvmem->owner)) {
 808                 dev_err(&nvmem->dev,
 809                         "could not increase module refcount for cell %s\n",
 810                         nvmem_dev_name(nvmem));
 811
 812                 put_device(&nvmem->dev);
 813                 return ERR_PTR(-EINVAL);
 814         }
 815
 816         kref_get(&nvmem->refcnt);
 817
 818         return nvmem;
 819 }
 820
 821 static void __nvmem_device_put(struct nvmem_device *nvmem)
 822 {
 823         put_device(&nvmem->dev);
 824         module_put(nvmem->owner);
 825         kref_put(&nvmem->refcnt, nvmem_device_release);
 826 }
 827
 828 #if IS_ENABLED(CONFIG_OF)
 829 /**
 830  * of_nvmem_device_get() - Get nvmem device from a given id
 831  *
 832  * @np: Device tree node that uses the nvmem device.
 833  * @id: nvmem name from nvmem-names property.
 834  *
 835  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
 836  * on success.
 837  */
 838 struct nvmem_device *of_nvmem_device_get(struct device_node *np, const char *id)
 839 {
 840
 841         struct device_node *nvmem_np;
 842         int index = 0;
 843
 844         if (id)
 845                 index = of_property_match_string(np, "nvmem-names", id);
 846
 847         nvmem_np = of_parse_phandle(np, "nvmem", index);
 848         if (!nvmem_np)
 849                 return ERR_PTR(-ENOENT);
 850
 851         return __nvmem_device_get(nvmem_np, NULL);
 852 }
 853 EXPORT_SYMBOL_GPL(of_nvmem_device_get);
 854 #endif
 855
 856 /**
 857  * nvmem_device_get() - Get nvmem device from a given id
 858  *
 859  * @dev: Device that uses the nvmem device.
 860  * @dev_name: name of the requested nvmem device.
 861  *
 862  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
 863  * on success.
 864  */
 865 struct nvmem_device *nvmem_device_get(struct device *dev, const char *dev_name)
 866 {
 867         if (dev->of_node) { /* try dt first */
 868                 struct nvmem_device *nvmem;
 869
 870                 nvmem = of_nvmem_device_get(dev->of_node, dev_name);
 871
 872                 if (!IS_ERR(nvmem) || PTR_ERR(nvmem) == -EPROBE_DEFER)
 873                         return nvmem;
 874
 875         }
 876
 877         return __nvmem_device_get(NULL, dev_name);
 878 }
 879 EXPORT_SYMBOL_GPL(nvmem_device_get);
 880
 881 static int devm_nvmem_device_match(struct device *dev, void *res, void *data)
 882 {
 883         struct nvmem_device **nvmem = res;
 884
 885         if (WARN_ON(!nvmem || !*nvmem))
 886                 return 0;
 887
 888         return *nvmem == data;
 889 }
 890
 891 static void devm_nvmem_device_release(struct device *dev, void *res)
 892 {
 893         nvmem_device_put(*(struct nvmem_device **)res);
 894 }
 895
 896 /**
 897  * devm_nvmem_device_put() - put alredy got nvmem device
 898  *
 899  * @dev: Device that uses the nvmem device.
 900  * @nvmem: pointer to nvmem device allocated by devm_nvmem_cell_get(),
 901  * that needs to be released.
 902  */
 903 void devm_nvmem_device_put(struct device *dev, struct nvmem_device *nvmem)
 904 {
 905         int ret;
 906
 907         ret = devres_release(dev, devm_nvmem_device_release,
 908                              devm_nvmem_device_match, nvmem);
 909
 910         WARN_ON(ret);
 911 }
 912 EXPORT_SYMBOL_GPL(devm_nvmem_device_put);
 913
 914 /**
 915  * nvmem_device_put() - put alredy got nvmem device
 916  *
 917  * @nvmem: pointer to nvmem device that needs to be released.
 918  */
 919 void nvmem_device_put(struct nvmem_device *nvmem)
 920 {
 921         __nvmem_device_put(nvmem);
 922 }
 923 EXPORT_SYMBOL_GPL(nvmem_device_put);
 924
 925 /**
 926  * devm_nvmem_device_get() - Get nvmem cell of device form a given id
 927  *
 928  * @dev: Device that requests the nvmem device.
 929  * @id: name id for the requested nvmem device.
 930  *
 931  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_cell
 932  * on success.  The nvmem_cell will be freed by the automatically once the
 933  * device is freed.
 934  */
 935 struct nvmem_device *devm_nvmem_device_get(struct device *dev, const char *id)
 936 {
 937         struct nvmem_device **ptr, *nvmem;
 938
 939         ptr = devres_alloc(devm_nvmem_device_release, sizeof(*ptr), GFP_KERNEL);
 940         if (!ptr)
 941                 return ERR_PTR(-ENOMEM);
 942
 943         nvmem = nvmem_device_get(dev, id);
 944         if (!IS_ERR(nvmem)) {
 945                 *ptr = nvmem;
 946                 devres_add(dev, ptr);
 947         } else {
 948                 devres_free(ptr);
 949         }
 950
 951         return nvmem;
 952 }
 953 EXPORT_SYMBOL_GPL(devm_nvmem_device_get);
 954
 955 static struct nvmem_cell *
 956 nvmem_cell_get_from_lookup(struct device *dev, const char *con_id)
 957 {
 958         struct nvmem_cell *cell = ERR_PTR(-ENOENT);
 959         struct nvmem_cell_lookup *lookup;
 960         struct nvmem_device *nvmem;
 961         const char *dev_id;
 962
 963         if (!dev)
 964                 return ERR_PTR(-EINVAL);
 965
 966         dev_id = dev_name(dev);
 967
 968         mutex_lock(&nvmem_lookup_mutex);
 969
 970         list_for_each_entry(lookup, &nvmem_lookup_list, node) {
 971                 if ((strcmp(lookup->dev_id, dev_id) == 0) &&
 972                     (strcmp(lookup->con_id, con_id) == 0)) {
 973                         /* This is the right entry. */
 974                         nvmem = __nvmem_device_get(NULL, lookup->nvmem_name);
 975                         if (IS_ERR(nvmem)) {
 976                                 /* Provider may not be registered yet. */
 977                                 cell = ERR_CAST(nvmem);
 978                                 break;
 979                         }
 980
 981                         cell = nvmem_find_cell_by_name(nvmem,
 982                                                        lookup->cell_name);
 983                         if (!cell) {
 984                                 __nvmem_device_put(nvmem);
 985                                 cell = ERR_PTR(-ENOENT);
 986                         }
 987                         break;
 988                 }
 989         }
 990
 991         mutex_unlock(&nvmem_lookup_mutex);
 992         return cell;
 993 }
 994
 995 #if IS_ENABLED(CONFIG_OF)
 996 static struct nvmem_cell *
 997 nvmem_find_cell_by_node(struct nvmem_device *nvmem, struct device_node *np)
 998 {
 999         struct nvmem_cell *iter, *cell = NULL;
1000
1001         mutex_lock(&nvmem_mutex);
1002         list_for_each_entry(iter, &nvmem->cells, node) {
1003                 if (np == iter->np) {
1004                         cell = iter;
1005                         break;
1006                 }
1007         }
1008         mutex_unlock(&nvmem_mutex);
1009
1010         return cell;
1011 }
1012
1013 /**
1014  * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
1015  *
1016  * @np: Device tree node that uses the nvmem cell.
1017  * @id: nvmem cell name from nvmem-cell-names property, or NULL
1018  *      for the cell at index 0 (the lone cell with no accompanying
1019  *      nvmem-cell-names property).
1020  *
1021  * Return: Will be an ERR_PTR() on error or a valid pointer
1022  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1023  * nvmem_cell_put().
1024  */
1025 struct nvmem_cell *of_nvmem_cell_get(struct device_node *np, const char *id)
1026 {
1027         struct device_node *cell_np, *nvmem_np;
1028         struct nvmem_device *nvmem;
1029         struct nvmem_cell *cell;
1030         int index = 0;
1031
1032         /* if cell name exists, find index to the name */
1033         if (id)
1034                 index = of_property_match_string(np, "nvmem-cell-names", id);
1035
1036         cell_np = of_parse_phandle(np, "nvmem-cells", index);
1037         if (!cell_np)
1038                 return ERR_PTR(-ENOENT);
1039
1040         nvmem_np = of_get_next_parent(cell_np);
1041         if (!nvmem_np)
1042                 return ERR_PTR(-EINVAL);
1043
1044         nvmem = __nvmem_device_get(nvmem_np, NULL);
1045         of_node_put(nvmem_np);
1046         if (IS_ERR(nvmem))
1047                 return ERR_CAST(nvmem);
1048
1049         cell = nvmem_find_cell_by_node(nvmem, cell_np);
1050         if (!cell) {
1051                 __nvmem_device_put(nvmem);
1052                 return ERR_PTR(-ENOENT);
1053         }
1054
1055         return cell;
1056 }
1057 EXPORT_SYMBOL_GPL(of_nvmem_cell_get);
1058 #endif
1059
1060 /**
1061  * nvmem_cell_get() - Get nvmem cell of device form a given cell name
1062  *
1063  * @dev: Device that requests the nvmem cell.
1064  * @id: nvmem cell name to get (this corresponds with the name from the
1065  *      nvmem-cell-names property for DT systems and with the con_id from
1066  *      the lookup entry for non-DT systems).
1067  *
1068  * Return: Will be an ERR_PTR() on error or a valid pointer
1069  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1070  * nvmem_cell_put().
1071  */
1072 struct nvmem_cell *nvmem_cell_get(struct device *dev, const char *id)
1073 {
1074         struct nvmem_cell *cell;
1075
1076         if (dev->of_node) { /* try dt first */
1077                 cell = of_nvmem_cell_get(dev->of_node, id);
1078                 if (!IS_ERR(cell) || PTR_ERR(cell) == -EPROBE_DEFER)
1079                         return cell;
1080         }
1081
1082         /* NULL cell id only allowed for device tree; invalid otherwise */
1083         if (!id)
1084                 return ERR_PTR(-EINVAL);
1085
1086         return nvmem_cell_get_from_lookup(dev, id);
1087 }
1088 EXPORT_SYMBOL_GPL(nvmem_cell_get);
1089
1090 static void devm_nvmem_cell_release(struct device *dev, void *res)
1091 {
1092         nvmem_cell_put(*(struct nvmem_cell **)res);
1093 }
1094
1095 /**
1096  * devm_nvmem_cell_get() - Get nvmem cell of device form a given id
1097  *
1098  * @dev: Device that requests the nvmem cell.
1099  * @id: nvmem cell name id to get.
1100  *
1101  * Return: Will be an ERR_PTR() on error or a valid pointer
1102  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1103  * automatically once the device is freed.
1104  */
1105 struct nvmem_cell *devm_nvmem_cell_get(struct device *dev, const char *id)
1106 {
1107         struct nvmem_cell **ptr, *cell;
1108
1109         ptr = devres_alloc(devm_nvmem_cell_release, sizeof(*ptr), GFP_KERNEL);
1110         if (!ptr)
1111                 return ERR_PTR(-ENOMEM);
1112
1113         cell = nvmem_cell_get(dev, id);
1114         if (!IS_ERR(cell)) {
1115                 *ptr = cell;
1116                 devres_add(dev, ptr);
1117         } else {
1118                 devres_free(ptr);
1119         }
1120
1121         return cell;
1122 }
1123 EXPORT_SYMBOL_GPL(devm_nvmem_cell_get);
1124
1125 static int devm_nvmem_cell_match(struct device *dev, void *res, void *data)
1126 {
1127         struct nvmem_cell **c = res;
1128
1129         if (WARN_ON(!c || !*c))
1130                 return 0;
1131
1132         return *c == data;
1133 }
1134
1135 /**
1136  * devm_nvmem_cell_put() - Release previously allocated nvmem cell
1137  * from devm_nvmem_cell_get.
1138  *
1139  * @dev: Device that requests the nvmem cell.
1140  * @cell: Previously allocated nvmem cell by devm_nvmem_cell_get().
1141  */
1142 void devm_nvmem_cell_put(struct device *dev, struct nvmem_cell *cell)
1143 {
1144         int ret;
1145
1146         ret = devres_release(dev, devm_nvmem_cell_release,
1147                                 devm_nvmem_cell_match, cell);
1148
1149         WARN_ON(ret);
1150 }
1151 EXPORT_SYMBOL(devm_nvmem_cell_put);
1152
1153 /**
1154  * nvmem_cell_put() - Release previously allocated nvmem cell.
1155  *
1156  * @cell: Previously allocated nvmem cell by nvmem_cell_get().
1157  */
1158 void nvmem_cell_put(struct nvmem_cell *cell)
1159 {
1160         struct nvmem_device *nvmem = cell->nvmem;
1161
1162         __nvmem_device_put(nvmem);
1163 }
1164 EXPORT_SYMBOL_GPL(nvmem_cell_put);
1165
1166 static void nvmem_shift_read_buffer_in_place(struct nvmem_cell *cell, void *buf)
1167 {
1168         u8 *p, *b;
1169         int i, extra, bit_offset = cell->bit_offset;
1170
1171         p = b = buf;
1172         if (bit_offset) {
1173                 /* First shift */
1174                 *b++ >>= bit_offset;
1175
1176                 /* setup rest of the bytes if any */
1177                 for (i = 1; i < cell->bytes; i++) {
1178                         /* Get bits from next byte and shift them towards msb */
1179                         *p |= *b << (BITS_PER_BYTE - bit_offset);
1180
1181                         p = b;
1182                         *b++ >>= bit_offset;
1183                 }
1184         } else {
1185                 /* point to the msb */
1186                 p += cell->bytes - 1;
1187         }
1188
1189         /* result fits in less bytes */
1190         extra = cell->bytes - DIV_ROUND_UP(cell->nbits, BITS_PER_BYTE);
1191         while (--extra >= 0)
1192                 *p-- = 0;
1193
1194         /* clear msb bits if any leftover in the last byte */
1195         *p &= GENMASK((cell->nbits%BITS_PER_BYTE) - 1, 0);
1196 }
1197
1198 static int __nvmem_cell_read(struct nvmem_device *nvmem,
1199                       struct nvmem_cell *cell,
1200                       void *buf, size_t *len)
1201 {
1202         int rc;
1203
1204         rc = nvmem_reg_read(nvmem, cell->offset, buf, cell->bytes);
1205
1206         if (rc)
1207                 return rc;
1208
1209         /* shift bits in-place */
1210         if (cell->bit_offset || cell->nbits)
1211                 nvmem_shift_read_buffer_in_place(cell, buf);
1212
1213         if (len)
1214                 *len = cell->bytes;
1215
1216         return 0;
1217 }
1218
1219 /**
1220  * nvmem_cell_read() - Read a given nvmem cell
1221  *
1222  * @cell: nvmem cell to be read.
1223  * @len: pointer to length of cell which will be populated on successful read;
1224  *       can be NULL.
1225  *
1226  * Return: ERR_PTR() on error or a valid pointer to a buffer on success. The
1227  * buffer should be freed by the consumer with a kfree().
1228  */
1229 void *nvmem_cell_read(struct nvmem_cell *cell, size_t *len)
1230 {
1231         struct nvmem_device *nvmem = cell->nvmem;
1232         u8 *buf;
1233         int rc;
1234
1235         if (!nvmem)
1236                 return ERR_PTR(-EINVAL);
1237
1238         buf = kzalloc(cell->bytes, GFP_KERNEL);
1239         if (!buf)
1240                 return ERR_PTR(-ENOMEM);
1241
1242         rc = __nvmem_cell_read(nvmem, cell, buf, len);
1243         if (rc) {
1244                 kfree(buf);
1245                 return ERR_PTR(rc);
1246         }
1247
1248         return buf;
1249 }
1250 EXPORT_SYMBOL_GPL(nvmem_cell_read);
1251
1252 static void *nvmem_cell_prepare_write_buffer(struct nvmem_cell *cell,
1253                                              u8 *_buf, int len)
1254 {
1255         struct nvmem_device *nvmem = cell->nvmem;
1256         int i, rc, nbits, bit_offset = cell->bit_offset;
1257         u8 v, *p, *buf, *b, pbyte, pbits;
1258
1259         nbits = cell->nbits;
1260         buf = kzalloc(cell->bytes, GFP_KERNEL);
1261         if (!buf)
1262                 return ERR_PTR(-ENOMEM);
1263
1264         memcpy(buf, _buf, len);
1265         p = b = buf;
1266
1267         if (bit_offset) {
1268                 pbyte = *b;
1269                 *b <<= bit_offset;
1270
1271                 /* setup the first byte with lsb bits from nvmem */
1272                 rc = nvmem_reg_read(nvmem, cell->offset, &v, 1);
1273                 if (rc)
1274                         goto err;
1275                 *b++ |= GENMASK(bit_offset - 1, 0) & v;
1276
1277                 /* setup rest of the byte if any */
1278                 for (i = 1; i < cell->bytes; i++) {
1279                         /* Get last byte bits and shift them towards lsb */
1280                         pbits = pbyte >> (BITS_PER_BYTE - 1 - bit_offset);
1281                         pbyte = *b;
1282                         p = b;
1283                         *b <<= bit_offset;
1284                         *b++ |= pbits;
1285                 }
1286         }
1287
1288         /* if it's not end on byte boundary */
1289         if ((nbits + bit_offset) % BITS_PER_BYTE) {
1290                 /* setup the last byte with msb bits from nvmem */
1291                 rc = nvmem_reg_read(nvmem,
1292                                     cell->offset + cell->bytes - 1, &v, 1);
1293                 if (rc)
1294                         goto err;
1295                 *p |= GENMASK(7, (nbits + bit_offset) % BITS_PER_BYTE) & v;
1296
1297         }
1298
1299         return buf;
1300 err:
1301         kfree(buf);
1302         return ERR_PTR(rc);
1303 }
1304
1305 /**
1306  * nvmem_cell_write() - Write to a given nvmem cell
1307  *
1308  * @cell: nvmem cell to be written.
1309  * @buf: Buffer to be written.
1310  * @len: length of buffer to be written to nvmem cell.
1311  *
1312  * Return: length of bytes written or negative on failure.
1313  */
1314 int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len)
1315 {
1316         struct nvmem_device *nvmem = cell->nvmem;
1317         int rc;
1318
1319         if (!nvmem || nvmem->read_only ||
1320             (cell->bit_offset == 0 && len != cell->bytes))
1321                 return -EINVAL;
1322
1323         if (cell->bit_offset || cell->nbits) {
1324                 buf = nvmem_cell_prepare_write_buffer(cell, buf, len);
1325                 if (IS_ERR(buf))
1326                         return PTR_ERR(buf);
1327         }
1328
1329         rc = nvmem_reg_write(nvmem, cell->offset, buf, cell->bytes);
1330
1331         /* free the tmp buffer */
1332         if (cell->bit_offset || cell->nbits)
1333                 kfree(buf);
1334
1335         if (rc)
1336                 return rc;
1337
1338         return len;
1339 }
1340 EXPORT_SYMBOL_GPL(nvmem_cell_write);
1341
1342 /**
1343  * nvmem_cell_read_u16() - Read a cell value as an u16
1344  *
1345  * @dev: Device that requests the nvmem cell.
1346  * @cell_id: Name of nvmem cell to read.
1347  * @val: pointer to output value.
1348  *
1349  * Return: 0 on success or negative errno.
1350  */
1351 int nvmem_cell_read_u16(struct device *dev, const char *cell_id, u16 *val)
1352 {
1353         struct nvmem_cell *cell;
1354         void *buf;
1355         size_t len;
1356
1357         cell = nvmem_cell_get(dev, cell_id);
1358         if (IS_ERR(cell))
1359                 return PTR_ERR(cell);
1360
1361         buf = nvmem_cell_read(cell, &len);
1362         if (IS_ERR(buf)) {
1363                 nvmem_cell_put(cell);
1364                 return PTR_ERR(buf);
1365         }
1366         if (len != sizeof(*val)) {
1367                 kfree(buf);
1368                 nvmem_cell_put(cell);
1369                 return -EINVAL;
1370         }
1371         memcpy(val, buf, sizeof(*val));
1372         kfree(buf);
1373         nvmem_cell_put(cell);
1374
1375         return 0;
1376 }
1377 EXPORT_SYMBOL_GPL(nvmem_cell_read_u16);
1378
1379 /**
1380  * nvmem_cell_read_u32() - Read a cell value as an u32
1381  *
1382  * @dev: Device that requests the nvmem cell.
1383  * @cell_id: Name of nvmem cell to read.
1384  * @val: pointer to output value.
1385  *
1386  * Return: 0 on success or negative errno.
1387  */
1388 int nvmem_cell_read_u32(struct device *dev, const char *cell_id, u32 *val)
1389 {
1390         struct nvmem_cell *cell;
1391         void *buf;
1392         size_t len;
1393
1394         cell = nvmem_cell_get(dev, cell_id);
1395         if (IS_ERR(cell))
1396                 return PTR_ERR(cell);
1397
1398         buf = nvmem_cell_read(cell, &len);
1399         if (IS_ERR(buf)) {
1400                 nvmem_cell_put(cell);
1401                 return PTR_ERR(buf);
1402         }
1403         if (len != sizeof(*val)) {
1404                 kfree(buf);
1405                 nvmem_cell_put(cell);
1406                 return -EINVAL;
1407         }
1408         memcpy(val, buf, sizeof(*val));
1409
1410         kfree(buf);
1411         nvmem_cell_put(cell);
1412         return 0;
1413 }
1414 EXPORT_SYMBOL_GPL(nvmem_cell_read_u32);
1415
1416 /**
1417  * nvmem_device_cell_read() - Read a given nvmem device and cell
1418  *
1419  * @nvmem: nvmem device to read from.
1420  * @info: nvmem cell info to be read.
1421  * @buf: buffer pointer which will be populated on successful read.
1422  *
1423  * Return: length of successful bytes read on success and negative
1424  * error code on error.
1425  */
1426 ssize_t nvmem_device_cell_read(struct nvmem_device *nvmem,
1427                            struct nvmem_cell_info *info, void *buf)
1428 {
1429         struct nvmem_cell cell;
1430         int rc;
1431         ssize_t len;
1432
1433         if (!nvmem)
1434                 return -EINVAL;
1435
1436         rc = nvmem_cell_info_to_nvmem_cell(nvmem, info, &cell);
1437         if (rc)
1438                 return rc;
1439
1440         rc = __nvmem_cell_read(nvmem, &cell, buf, &len);
1441         if (rc)
1442                 return rc;
1443
1444         return len;
1445 }
1446 EXPORT_SYMBOL_GPL(nvmem_device_cell_read);
1447
1448 /**
1449  * nvmem_device_cell_write() - Write cell to a given nvmem device
1450  *
1451  * @nvmem: nvmem device to be written to.
1452  * @info: nvmem cell info to be written.
1453  * @buf: buffer to be written to cell.
1454  *
1455  * Return: length of bytes written or negative error code on failure.
1456  */
1457 int nvmem_device_cell_write(struct nvmem_device *nvmem,
1458                             struct nvmem_cell_info *info, void *buf)
1459 {
1460         struct nvmem_cell cell;
1461         int rc;
1462
1463         if (!nvmem)
1464                 return -EINVAL;
1465
1466         rc = nvmem_cell_info_to_nvmem_cell(nvmem, info, &cell);
1467         if (rc)
1468                 return rc;
1469
1470         return nvmem_cell_write(&cell, buf, cell.bytes);
1471 }
1472 EXPORT_SYMBOL_GPL(nvmem_device_cell_write);
1473
1474 /**
1475  * nvmem_device_read() - Read from a given nvmem device
1476  *
1477  * @nvmem: nvmem device to read from.
1478  * @offset: offset in nvmem device.
1479  * @bytes: number of bytes to read.
1480  * @buf: buffer pointer which will be populated on successful read.
1481  *
1482  * Return: length of successful bytes read on success and negative
1483  * error code on error.
1484  */
1485 int nvmem_device_read(struct nvmem_device *nvmem,
1486                       unsigned int offset,
1487                       size_t bytes, void *buf)
1488 {
1489         int rc;
1490
1491         if (!nvmem)
1492                 return -EINVAL;
1493
1494         rc = nvmem_reg_read(nvmem, offset, buf, bytes);
1495
1496         if (rc)
1497                 return rc;
1498
1499         return bytes;
1500 }
1501 EXPORT_SYMBOL_GPL(nvmem_device_read);
1502
1503 /**
1504  * nvmem_device_write() - Write cell to a given nvmem device
1505  *
1506  * @nvmem: nvmem device to be written to.
1507  * @offset: offset in nvmem device.
1508  * @bytes: number of bytes to write.
1509  * @buf: buffer to be written.
1510  *
1511  * Return: length of bytes written or negative error code on failure.
1512  */
1513 int nvmem_device_write(struct nvmem_device *nvmem,
1514                        unsigned int offset,
1515                        size_t bytes, void *buf)
1516 {
1517         int rc;
1518
1519         if (!nvmem)
1520                 return -EINVAL;
1521
1522         rc = nvmem_reg_write(nvmem, offset, buf, bytes);
1523
1524         if (rc)
1525                 return rc;
1526
1527
1528         return bytes;
1529 }
1530 EXPORT_SYMBOL_GPL(nvmem_device_write);
1531
1532 /**
1533  * nvmem_add_cell_table() - register a table of cell info entries
1534  *
1535  * @table: table of cell info entries
1536  */
1537 void nvmem_add_cell_table(struct nvmem_cell_table *table)
1538 {
1539         mutex_lock(&nvmem_cell_mutex);
1540         list_add_tail(&table->node, &nvmem_cell_tables);
1541         mutex_unlock(&nvmem_cell_mutex);
1542 }
1543 EXPORT_SYMBOL_GPL(nvmem_add_cell_table);
1544
1545 /**
1546  * nvmem_del_cell_table() - remove a previously registered cell info table
1547  *
1548  * @table: table of cell info entries
1549  */
1550 void nvmem_del_cell_table(struct nvmem_cell_table *table)
1551 {
1552         mutex_lock(&nvmem_cell_mutex);
1553         list_del(&table->node);
1554         mutex_unlock(&nvmem_cell_mutex);
1555 }
1556 EXPORT_SYMBOL_GPL(nvmem_del_cell_table);
1557
1558 /**
1559  * nvmem_add_cell_lookups() - register a list of cell lookup entries
1560  *
1561  * @entries: array of cell lookup entries
1562  * @nentries: number of cell lookup entries in the array
1563  */
1564 void nvmem_add_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
1565 {
1566         int i;
1567
1568         mutex_lock(&nvmem_lookup_mutex);
1569         for (i = 0; i < nentries; i++)
1570                 list_add_tail(&entries[i].node, &nvmem_lookup_list);
1571         mutex_unlock(&nvmem_lookup_mutex);
1572 }
1573 EXPORT_SYMBOL_GPL(nvmem_add_cell_lookups);
1574
1575 /**
1576  * nvmem_del_cell_lookups() - remove a list of previously added cell lookup
1577  *                            entries
1578  *
1579  * @entries: array of cell lookup entries
1580  * @nentries: number of cell lookup entries in the array
1581  */
1582 void nvmem_del_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
1583 {
1584         int i;
1585
1586         mutex_lock(&nvmem_lookup_mutex);
1587         for (i = 0; i < nentries; i++)
1588                 list_del(&entries[i].node);
1589         mutex_unlock(&nvmem_lookup_mutex);
1590 }
1591 EXPORT_SYMBOL_GPL(nvmem_del_cell_lookups);
1592
1593 /**
1594  * nvmem_dev_name() - Get the name of a given nvmem device.
1595  *
1596  * @nvmem: nvmem device.
1597  *
1598  * Return: name of the nvmem device.
1599  */
1600 const char *nvmem_dev_name(struct nvmem_device *nvmem)
1601 {
1602         return dev_name(&nvmem->dev);
1603 }
1604 EXPORT_SYMBOL_GPL(nvmem_dev_name);
1605
1606 static int __init nvmem_init(void)
1607 {
1608         return bus_register(&nvmem_bus_type);
1609 }
1610
1611 static void __exit nvmem_exit(void)
1612 {
1613         bus_unregister(&nvmem_bus_type);
1614 }
1615
1616 subsys_initcall(nvmem_init);
1617 module_exit(nvmem_exit);
1618
1619 MODULE_AUTHOR("Srinivas Kandagatla <srinivas.kandagatla@linaro.org");
1620 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com");
1621 MODULE_DESCRIPTION("nvmem Driver Core");
1622 MODULE_LICENSE("GPL v2");