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/gpio/consumer.h>
  19 #include <linux/of.h>
  20 #include <linux/of_device.h>
  21 #include <linux/slab.h>
  22
  23 struct nvmem_device {
  24         struct module           *owner;
  25         struct device           dev;
  26         int                     stride;
  27         int                     word_size;
  28         int                     id;
  29         struct kref             refcnt;
  30         size_t                  size;
  31         bool                    read_only;
  32         bool                    root_only;
  33         int                     flags;
  34         enum nvmem_type         type;
  35         struct bin_attribute    eeprom;
  36         struct device           *base_dev;
  37         struct list_head        cells;
  38         const struct nvmem_keepout *keepout;
  39         unsigned int            nkeepout;
  40         nvmem_reg_read_t        reg_read;
  41         nvmem_reg_write_t       reg_write;
  42         struct gpio_desc        *wp_gpio;
  43         struct nvmem_layout     *layout;
  44         void *priv;
  45 };
  46
  47 #define to_nvmem_device(d) container_of(d, struct nvmem_device, dev)
  48
  49 #define FLAG_COMPAT             BIT(0)
  50 struct nvmem_cell_entry {
  51         const char              *name;
  52         int                     offset;
  53         size_t                  raw_len;
  54         int                     bytes;
  55         int                     bit_offset;
  56         int                     nbits;
  57         nvmem_cell_post_process_t read_post_process;
  58         void                    *priv;
  59         struct device_node      *np;
  60         struct nvmem_device     *nvmem;
  61         struct list_head        node;
  62 };
  63
  64 struct nvmem_cell {
  65         struct nvmem_cell_entry *entry;
  66         const char              *id;
  67         int                     index;
  68 };
  69
  70 static DEFINE_MUTEX(nvmem_mutex);
  71 static DEFINE_IDA(nvmem_ida);
  72
  73 static DEFINE_MUTEX(nvmem_cell_mutex);
  74 static LIST_HEAD(nvmem_cell_tables);
  75
  76 static DEFINE_MUTEX(nvmem_lookup_mutex);
  77 static LIST_HEAD(nvmem_lookup_list);
  78
  79 static BLOCKING_NOTIFIER_HEAD(nvmem_notifier);
  80
  81 static DEFINE_SPINLOCK(nvmem_layout_lock);
  82 static LIST_HEAD(nvmem_layouts);
  83
  84 static int __nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
  85                             void *val, size_t bytes)
  86 {
  87         if (nvmem->reg_read)
  88                 return nvmem->reg_read(nvmem->priv, offset, val, bytes);
  89
  90         return -EINVAL;
  91 }
  92
  93 static int __nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
  94                              void *val, size_t bytes)
  95 {
  96         int ret;
  97
  98         if (nvmem->reg_write) {
  99                 gpiod_set_value_cansleep(nvmem->wp_gpio, 0);
 100                 ret = nvmem->reg_write(nvmem->priv, offset, val, bytes);
 101                 gpiod_set_value_cansleep(nvmem->wp_gpio, 1);
 102                 return ret;
 103         }
 104
 105         return -EINVAL;
 106 }
 107
 108 static int nvmem_access_with_keepouts(struct nvmem_device *nvmem,
 109                                       unsigned int offset, void *val,
 110                                       size_t bytes, int write)
 111 {
 112
 113         unsigned int end = offset + bytes;
 114         unsigned int kend, ksize;
 115         const struct nvmem_keepout *keepout = nvmem->keepout;
 116         const struct nvmem_keepout *keepoutend = keepout + nvmem->nkeepout;
 117         int rc;
 118
 119         /*
 120          * Skip all keepouts before the range being accessed.
 121          * Keepouts are sorted.
 122          */
 123         while ((keepout < keepoutend) && (keepout->end <= offset))
 124                 keepout++;
 125
 126         while ((offset < end) && (keepout < keepoutend)) {
 127                 /* Access the valid portion before the keepout. */
 128                 if (offset < keepout->start) {
 129                         kend = min(end, keepout->start);
 130                         ksize = kend - offset;
 131                         if (write)
 132                                 rc = __nvmem_reg_write(nvmem, offset, val, ksize);
 133                         else
 134                                 rc = __nvmem_reg_read(nvmem, offset, val, ksize);
 135
 136                         if (rc)
 137                                 return rc;
 138
 139                         offset += ksize;
 140                         val += ksize;
 141                 }
 142
 143                 /*
 144                  * Now we're aligned to the start of this keepout zone. Go
 145                  * through it.
 146                  */
 147                 kend = min(end, keepout->end);
 148                 ksize = kend - offset;
 149                 if (!write)
 150                         memset(val, keepout->value, ksize);
 151
 152                 val += ksize;
 153                 offset += ksize;
 154                 keepout++;
 155         }
 156
 157         /*
 158          * If we ran out of keepouts but there's still stuff to do, send it
 159          * down directly
 160          */
 161         if (offset < end) {
 162                 ksize = end - offset;
 163                 if (write)
 164                         return __nvmem_reg_write(nvmem, offset, val, ksize);
 165                 else
 166                         return __nvmem_reg_read(nvmem, offset, val, ksize);
 167         }
 168
 169         return 0;
 170 }
 171
 172 static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
 173                           void *val, size_t bytes)
 174 {
 175         if (!nvmem->nkeepout)
 176                 return __nvmem_reg_read(nvmem, offset, val, bytes);
 177
 178         return nvmem_access_with_keepouts(nvmem, offset, val, bytes, false);
 179 }
 180
 181 static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
 182                            void *val, size_t bytes)
 183 {
 184         if (!nvmem->nkeepout)
 185                 return __nvmem_reg_write(nvmem, offset, val, bytes);
 186
 187         return nvmem_access_with_keepouts(nvmem, offset, val, bytes, true);
 188 }
 189
 190 #ifdef CONFIG_NVMEM_SYSFS
 191 static const char * const nvmem_type_str[] = {
 192         [NVMEM_TYPE_UNKNOWN] = "Unknown",
 193         [NVMEM_TYPE_EEPROM] = "EEPROM",
 194         [NVMEM_TYPE_OTP] = "OTP",
 195         [NVMEM_TYPE_BATTERY_BACKED] = "Battery backed",
 196         [NVMEM_TYPE_FRAM] = "FRAM",
 197 };
 198
 199 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 200 static struct lock_class_key eeprom_lock_key;
 201 #endif
 202
 203 static ssize_t type_show(struct device *dev,
 204                          struct device_attribute *attr, char *buf)
 205 {
 206         struct nvmem_device *nvmem = to_nvmem_device(dev);
 207
 208         return sprintf(buf, "%s\n", nvmem_type_str[nvmem->type]);
 209 }
 210
 211 static DEVICE_ATTR_RO(type);
 212
 213 static struct attribute *nvmem_attrs[] = {
 214         &dev_attr_type.attr,
 215         NULL,
 216 };
 217
 218 static ssize_t bin_attr_nvmem_read(struct file *filp, struct kobject *kobj,
 219                                    struct bin_attribute *attr, char *buf,
 220                                    loff_t pos, size_t count)
 221 {
 222         struct device *dev;
 223         struct nvmem_device *nvmem;
 224         int rc;
 225
 226         if (attr->private)
 227                 dev = attr->private;
 228         else
 229                 dev = kobj_to_dev(kobj);
 230         nvmem = to_nvmem_device(dev);
 231
 232         /* Stop the user from reading */
 233         if (pos >= nvmem->size)
 234                 return 0;
 235
 236         if (!IS_ALIGNED(pos, nvmem->stride))
 237                 return -EINVAL;
 238
 239         if (count < nvmem->word_size)
 240                 return -EINVAL;
 241
 242         if (pos + count > nvmem->size)
 243                 count = nvmem->size - pos;
 244
 245         count = round_down(count, nvmem->word_size);
 246
 247         if (!nvmem->reg_read)
 248                 return -EPERM;
 249
 250         rc = nvmem_reg_read(nvmem, pos, buf, count);
 251
 252         if (rc)
 253                 return rc;
 254
 255         return count;
 256 }
 257
 258 static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj,
 259                                     struct bin_attribute *attr, char *buf,
 260                                     loff_t pos, size_t count)
 261 {
 262         struct device *dev;
 263         struct nvmem_device *nvmem;
 264         int rc;
 265
 266         if (attr->private)
 267                 dev = attr->private;
 268         else
 269                 dev = kobj_to_dev(kobj);
 270         nvmem = to_nvmem_device(dev);
 271
 272         /* Stop the user from writing */
 273         if (pos >= nvmem->size)
 274                 return -EFBIG;
 275
 276         if (!IS_ALIGNED(pos, nvmem->stride))
 277                 return -EINVAL;
 278
 279         if (count < nvmem->word_size)
 280                 return -EINVAL;
 281
 282         if (pos + count > nvmem->size)
 283                 count = nvmem->size - pos;
 284
 285         count = round_down(count, nvmem->word_size);
 286
 287         if (!nvmem->reg_write)
 288                 return -EPERM;
 289
 290         rc = nvmem_reg_write(nvmem, pos, buf, count);
 291
 292         if (rc)
 293                 return rc;
 294
 295         return count;
 296 }
 297
 298 static umode_t nvmem_bin_attr_get_umode(struct nvmem_device *nvmem)
 299 {
 300         umode_t mode = 0400;
 301
 302         if (!nvmem->root_only)
 303                 mode |= 0044;
 304
 305         if (!nvmem->read_only)
 306                 mode |= 0200;
 307
 308         if (!nvmem->reg_write)
 309                 mode &= ~0200;
 310
 311         if (!nvmem->reg_read)
 312                 mode &= ~0444;
 313
 314         return mode;
 315 }
 316
 317 static umode_t nvmem_bin_attr_is_visible(struct kobject *kobj,
 318                                          struct bin_attribute *attr, int i)
 319 {
 320         struct device *dev = kobj_to_dev(kobj);
 321         struct nvmem_device *nvmem = to_nvmem_device(dev);
 322
 323         attr->size = nvmem->size;
 324
 325         return nvmem_bin_attr_get_umode(nvmem);
 326 }
 327
 328 /* default read/write permissions */
 329 static struct bin_attribute bin_attr_rw_nvmem = {
 330         .attr   = {
 331                 .name   = "nvmem",
 332                 .mode   = 0644,
 333         },
 334         .read   = bin_attr_nvmem_read,
 335         .write  = bin_attr_nvmem_write,
 336 };
 337
 338 static struct bin_attribute *nvmem_bin_attributes[] = {
 339         &bin_attr_rw_nvmem,
 340         NULL,
 341 };
 342
 343 static const struct attribute_group nvmem_bin_group = {
 344         .bin_attrs      = nvmem_bin_attributes,
 345         .attrs          = nvmem_attrs,
 346         .is_bin_visible = nvmem_bin_attr_is_visible,
 347 };
 348
 349 static const struct attribute_group *nvmem_dev_groups[] = {
 350         &nvmem_bin_group,
 351         NULL,
 352 };
 353
 354 static struct bin_attribute bin_attr_nvmem_eeprom_compat = {
 355         .attr   = {
 356                 .name   = "eeprom",
 357         },
 358         .read   = bin_attr_nvmem_read,
 359         .write  = bin_attr_nvmem_write,
 360 };
 361
 362 /*
 363  * nvmem_setup_compat() - Create an additional binary entry in
 364  * drivers sys directory, to be backwards compatible with the older
 365  * drivers/misc/eeprom drivers.
 366  */
 367 static int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
 368                                     const struct nvmem_config *config)
 369 {
 370         int rval;
 371
 372         if (!config->compat)
 373                 return 0;
 374
 375         if (!config->base_dev)
 376                 return -EINVAL;
 377
 378         if (config->type == NVMEM_TYPE_FRAM)
 379                 bin_attr_nvmem_eeprom_compat.attr.name = "fram";
 380
 381         nvmem->eeprom = bin_attr_nvmem_eeprom_compat;
 382         nvmem->eeprom.attr.mode = nvmem_bin_attr_get_umode(nvmem);
 383         nvmem->eeprom.size = nvmem->size;
 384 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 385         nvmem->eeprom.attr.key = &eeprom_lock_key;
 386 #endif
 387         nvmem->eeprom.private = &nvmem->dev;
 388         nvmem->base_dev = config->base_dev;
 389
 390         rval = device_create_bin_file(nvmem->base_dev, &nvmem->eeprom);
 391         if (rval) {
 392                 dev_err(&nvmem->dev,
 393                         "Failed to create eeprom binary file %d\n", rval);
 394                 return rval;
 395         }
 396
 397         nvmem->flags |= FLAG_COMPAT;
 398
 399         return 0;
 400 }
 401
 402 static void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem,
 403                               const struct nvmem_config *config)
 404 {
 405         if (config->compat)
 406                 device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
 407 }
 408
 409 #else /* CONFIG_NVMEM_SYSFS */
 410
 411 static int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
 412                                     const struct nvmem_config *config)
 413 {
 414         return -ENOSYS;
 415 }
 416 static void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem,
 417                                       const struct nvmem_config *config)
 418 {
 419 }
 420
 421 #endif /* CONFIG_NVMEM_SYSFS */
 422
 423 static void nvmem_release(struct device *dev)
 424 {
 425         struct nvmem_device *nvmem = to_nvmem_device(dev);
 426
 427         ida_free(&nvmem_ida, nvmem->id);
 428         gpiod_put(nvmem->wp_gpio);
 429         kfree(nvmem);
 430 }
 431
 432 static const struct device_type nvmem_provider_type = {
 433         .release        = nvmem_release,
 434 };
 435
 436 static struct bus_type nvmem_bus_type = {
 437         .name           = "nvmem",
 438 };
 439
 440 static void nvmem_cell_entry_drop(struct nvmem_cell_entry *cell)
 441 {
 442         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_REMOVE, cell);
 443         mutex_lock(&nvmem_mutex);
 444         list_del(&cell->node);
 445         mutex_unlock(&nvmem_mutex);
 446         of_node_put(cell->np);
 447         kfree_const(cell->name);
 448         kfree(cell);
 449 }
 450
 451 static void nvmem_device_remove_all_cells(const struct nvmem_device *nvmem)
 452 {
 453         struct nvmem_cell_entry *cell, *p;
 454
 455         list_for_each_entry_safe(cell, p, &nvmem->cells, node)
 456                 nvmem_cell_entry_drop(cell);
 457 }
 458
 459 static void nvmem_cell_entry_add(struct nvmem_cell_entry *cell)
 460 {
 461         mutex_lock(&nvmem_mutex);
 462         list_add_tail(&cell->node, &cell->nvmem->cells);
 463         mutex_unlock(&nvmem_mutex);
 464         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_ADD, cell);
 465 }
 466
 467 static int nvmem_cell_info_to_nvmem_cell_entry_nodup(struct nvmem_device *nvmem,
 468                                                      const struct nvmem_cell_info *info,
 469                                                      struct nvmem_cell_entry *cell)
 470 {
 471         cell->nvmem = nvmem;
 472         cell->offset = info->offset;
 473         cell->raw_len = info->raw_len ?: info->bytes;
 474         cell->bytes = info->bytes;
 475         cell->name = info->name;
 476         cell->read_post_process = info->read_post_process;
 477         cell->priv = info->priv;
 478
 479         cell->bit_offset = info->bit_offset;
 480         cell->nbits = info->nbits;
 481         cell->np = info->np;
 482
 483         if (cell->nbits)
 484                 cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
 485                                            BITS_PER_BYTE);
 486
 487         if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
 488                 dev_err(&nvmem->dev,
 489                         "cell %s unaligned to nvmem stride %d\n",
 490                         cell->name ?: "<unknown>", nvmem->stride);
 491                 return -EINVAL;
 492         }
 493
 494         return 0;
 495 }
 496
 497 static int nvmem_cell_info_to_nvmem_cell_entry(struct nvmem_device *nvmem,
 498                                                const struct nvmem_cell_info *info,
 499                                                struct nvmem_cell_entry *cell)
 500 {
 501         int err;
 502
 503         err = nvmem_cell_info_to_nvmem_cell_entry_nodup(nvmem, info, cell);
 504         if (err)
 505                 return err;
 506
 507         cell->name = kstrdup_const(info->name, GFP_KERNEL);
 508         if (!cell->name)
 509                 return -ENOMEM;
 510
 511         return 0;
 512 }
 513
 514 /**
 515  * nvmem_add_one_cell() - Add one cell information to an nvmem device
 516  *
 517  * @nvmem: nvmem device to add cells to.
 518  * @info: nvmem cell info to add to the device
 519  *
 520  * Return: 0 or negative error code on failure.
 521  */
 522 int nvmem_add_one_cell(struct nvmem_device *nvmem,
 523                        const struct nvmem_cell_info *info)
 524 {
 525         struct nvmem_cell_entry *cell;
 526         int rval;
 527
 528         cell = kzalloc(sizeof(*cell), GFP_KERNEL);
 529         if (!cell)
 530                 return -ENOMEM;
 531
 532         rval = nvmem_cell_info_to_nvmem_cell_entry(nvmem, info, cell);
 533         if (rval) {
 534                 kfree(cell);
 535                 return rval;
 536         }
 537
 538         nvmem_cell_entry_add(cell);
 539
 540         return 0;
 541 }
 542 EXPORT_SYMBOL_GPL(nvmem_add_one_cell);
 543
 544 /**
 545  * nvmem_add_cells() - Add cell information to an nvmem device
 546  *
 547  * @nvmem: nvmem device to add cells to.
 548  * @info: nvmem cell info to add to the device
 549  * @ncells: number of cells in info
 550  *
 551  * Return: 0 or negative error code on failure.
 552  */
 553 static int nvmem_add_cells(struct nvmem_device *nvmem,
 554                     const struct nvmem_cell_info *info,
 555                     int ncells)
 556 {
 557         int i, rval;
 558
 559         for (i = 0; i < ncells; i++) {
 560                 rval = nvmem_add_one_cell(nvmem, &info[i]);
 561                 if (rval)
 562                         return rval;
 563         }
 564
 565         return 0;
 566 }
 567
 568 /**
 569  * nvmem_register_notifier() - Register a notifier block for nvmem events.
 570  *
 571  * @nb: notifier block to be called on nvmem events.
 572  *
 573  * Return: 0 on success, negative error number on failure.
 574  */
 575 int nvmem_register_notifier(struct notifier_block *nb)
 576 {
 577         return blocking_notifier_chain_register(&nvmem_notifier, nb);
 578 }
 579 EXPORT_SYMBOL_GPL(nvmem_register_notifier);
 580
 581 /**
 582  * nvmem_unregister_notifier() - Unregister a notifier block for nvmem events.
 583  *
 584  * @nb: notifier block to be unregistered.
 585  *
 586  * Return: 0 on success, negative error number on failure.
 587  */
 588 int nvmem_unregister_notifier(struct notifier_block *nb)
 589 {
 590         return blocking_notifier_chain_unregister(&nvmem_notifier, nb);
 591 }
 592 EXPORT_SYMBOL_GPL(nvmem_unregister_notifier);
 593
 594 static int nvmem_add_cells_from_table(struct nvmem_device *nvmem)
 595 {
 596         const struct nvmem_cell_info *info;
 597         struct nvmem_cell_table *table;
 598         struct nvmem_cell_entry *cell;
 599         int rval = 0, i;
 600
 601         mutex_lock(&nvmem_cell_mutex);
 602         list_for_each_entry(table, &nvmem_cell_tables, node) {
 603                 if (strcmp(nvmem_dev_name(nvmem), table->nvmem_name) == 0) {
 604                         for (i = 0; i < table->ncells; i++) {
 605                                 info = &table->cells[i];
 606
 607                                 cell = kzalloc(sizeof(*cell), GFP_KERNEL);
 608                                 if (!cell) {
 609                                         rval = -ENOMEM;
 610                                         goto out;
 611                                 }
 612
 613                                 rval = nvmem_cell_info_to_nvmem_cell_entry(nvmem, info, cell);
 614                                 if (rval) {
 615                                         kfree(cell);
 616                                         goto out;
 617                                 }
 618
 619                                 nvmem_cell_entry_add(cell);
 620                         }
 621                 }
 622         }
 623
 624 out:
 625         mutex_unlock(&nvmem_cell_mutex);
 626         return rval;
 627 }
 628
 629 static struct nvmem_cell_entry *
 630 nvmem_find_cell_entry_by_name(struct nvmem_device *nvmem, const char *cell_id)
 631 {
 632         struct nvmem_cell_entry *iter, *cell = NULL;
 633
 634         mutex_lock(&nvmem_mutex);
 635         list_for_each_entry(iter, &nvmem->cells, node) {
 636                 if (strcmp(cell_id, iter->name) == 0) {
 637                         cell = iter;
 638                         break;
 639                 }
 640         }
 641         mutex_unlock(&nvmem_mutex);
 642
 643         return cell;
 644 }
 645
 646 static int nvmem_validate_keepouts(struct nvmem_device *nvmem)
 647 {
 648         unsigned int cur = 0;
 649         const struct nvmem_keepout *keepout = nvmem->keepout;
 650         const struct nvmem_keepout *keepoutend = keepout + nvmem->nkeepout;
 651
 652         while (keepout < keepoutend) {
 653                 /* Ensure keepouts are sorted and don't overlap. */
 654                 if (keepout->start < cur) {
 655                         dev_err(&nvmem->dev,
 656                                 "Keepout regions aren't sorted or overlap.\n");
 657
 658                         return -ERANGE;
 659                 }
 660
 661                 if (keepout->end < keepout->start) {
 662                         dev_err(&nvmem->dev,
 663                                 "Invalid keepout region.\n");
 664
 665                         return -EINVAL;
 666                 }
 667
 668                 /*
 669                  * Validate keepouts (and holes between) don't violate
 670                  * word_size constraints.
 671                  */
 672                 if ((keepout->end - keepout->start < nvmem->word_size) ||
 673                     ((keepout->start != cur) &&
 674                      (keepout->start - cur < nvmem->word_size))) {
 675
 676                         dev_err(&nvmem->dev,
 677                                 "Keepout regions violate word_size constraints.\n");
 678
 679                         return -ERANGE;
 680                 }
 681
 682                 /* Validate keepouts don't violate stride (alignment). */
 683                 if (!IS_ALIGNED(keepout->start, nvmem->stride) ||
 684                     !IS_ALIGNED(keepout->end, nvmem->stride)) {
 685
 686                         dev_err(&nvmem->dev,
 687                                 "Keepout regions violate stride.\n");
 688
 689                         return -EINVAL;
 690                 }
 691
 692                 cur = keepout->end;
 693                 keepout++;
 694         }
 695
 696         return 0;
 697 }
 698
 699 static int nvmem_add_cells_from_dt(struct nvmem_device *nvmem, struct device_node *np)
 700 {
 701         struct nvmem_layout *layout = nvmem->layout;
 702         struct device *dev = &nvmem->dev;
 703         struct device_node *child;
 704         const __be32 *addr;
 705         int len, ret;
 706
 707         for_each_child_of_node(np, child) {
 708                 struct nvmem_cell_info info = {0};
 709
 710                 addr = of_get_property(child, "reg", &len);
 711                 if (!addr)
 712                         continue;
 713                 if (len < 2 * sizeof(u32)) {
 714                         dev_err(dev, "nvmem: invalid reg on %pOF\n", child);
 715                         of_node_put(child);
 716                         return -EINVAL;
 717                 }
 718
 719                 info.offset = be32_to_cpup(addr++);
 720                 info.bytes = be32_to_cpup(addr);
 721                 info.name = kasprintf(GFP_KERNEL, "%pOFn", child);
 722
 723                 addr = of_get_property(child, "bits", &len);
 724                 if (addr && len == (2 * sizeof(u32))) {
 725                         info.bit_offset = be32_to_cpup(addr++);
 726                         info.nbits = be32_to_cpup(addr);
 727                 }
 728
 729                 info.np = of_node_get(child);
 730
 731                 if (layout && layout->fixup_cell_info)
 732                         layout->fixup_cell_info(nvmem, layout, &info);
 733
 734                 ret = nvmem_add_one_cell(nvmem, &info);
 735                 kfree(info.name);
 736                 if (ret) {
 737                         of_node_put(child);
 738                         return ret;
 739                 }
 740         }
 741
 742         return 0;
 743 }
 744
 745 static int nvmem_add_cells_from_legacy_of(struct nvmem_device *nvmem)
 746 {
 747         return nvmem_add_cells_from_dt(nvmem, nvmem->dev.of_node);
 748 }
 749
 750 static int nvmem_add_cells_from_fixed_layout(struct nvmem_device *nvmem)
 751 {
 752         struct device_node *layout_np;
 753         int err = 0;
 754
 755         layout_np = of_nvmem_layout_get_container(nvmem);
 756         if (!layout_np)
 757                 return 0;
 758
 759         if (of_device_is_compatible(layout_np, "fixed-layout"))
 760                 err = nvmem_add_cells_from_dt(nvmem, layout_np);
 761
 762         of_node_put(layout_np);
 763
 764         return err;
 765 }
 766
 767 int __nvmem_layout_register(struct nvmem_layout *layout, struct module *owner)
 768 {
 769         layout->owner = owner;
 770
 771         spin_lock(&nvmem_layout_lock);
 772         list_add(&layout->node, &nvmem_layouts);
 773         spin_unlock(&nvmem_layout_lock);
 774
 775         return 0;
 776 }
 777 EXPORT_SYMBOL_GPL(__nvmem_layout_register);
 778
 779 void nvmem_layout_unregister(struct nvmem_layout *layout)
 780 {
 781         spin_lock(&nvmem_layout_lock);
 782         list_del(&layout->node);
 783         spin_unlock(&nvmem_layout_lock);
 784 }
 785 EXPORT_SYMBOL_GPL(nvmem_layout_unregister);
 786
 787 static struct nvmem_layout *nvmem_layout_get(struct nvmem_device *nvmem)
 788 {
 789         struct device_node *layout_np, *np = nvmem->dev.of_node;
 790         struct nvmem_layout *l, *layout = ERR_PTR(-EPROBE_DEFER);
 791
 792         layout_np = of_get_child_by_name(np, "nvmem-layout");
 793         if (!layout_np)
 794                 return NULL;
 795
 796         /*
 797          * In case the nvmem device was built-in while the layout was built as a
 798          * module, we shall manually request the layout driver loading otherwise
 799          * we'll never have any match.
 800          */
 801         of_request_module(layout_np);
 802
 803         spin_lock(&nvmem_layout_lock);
 804
 805         list_for_each_entry(l, &nvmem_layouts, node) {
 806                 if (of_match_node(l->of_match_table, layout_np)) {
 807                         if (try_module_get(l->owner))
 808                                 layout = l;
 809
 810                         break;
 811                 }
 812         }
 813
 814         spin_unlock(&nvmem_layout_lock);
 815         of_node_put(layout_np);
 816
 817         return layout;
 818 }
 819
 820 static void nvmem_layout_put(struct nvmem_layout *layout)
 821 {
 822         if (layout)
 823                 module_put(layout->owner);
 824 }
 825
 826 static int nvmem_add_cells_from_layout(struct nvmem_device *nvmem)
 827 {
 828         struct nvmem_layout *layout = nvmem->layout;
 829         int ret;
 830
 831         if (layout && layout->add_cells) {
 832                 ret = layout->add_cells(&nvmem->dev, nvmem, layout);
 833                 if (ret)
 834                         return ret;
 835         }
 836
 837         return 0;
 838 }
 839
 840 #if IS_ENABLED(CONFIG_OF)
 841 /**
 842  * of_nvmem_layout_get_container() - Get OF node to layout container.
 843  *
 844  * @nvmem: nvmem device.
 845  *
 846  * Return: a node pointer with refcount incremented or NULL if no
 847  * container exists. Use of_node_put() on it when done.
 848  */
 849 struct device_node *of_nvmem_layout_get_container(struct nvmem_device *nvmem)
 850 {
 851         return of_get_child_by_name(nvmem->dev.of_node, "nvmem-layout");
 852 }
 853 EXPORT_SYMBOL_GPL(of_nvmem_layout_get_container);
 854 #endif
 855
 856 const void *nvmem_layout_get_match_data(struct nvmem_device *nvmem,
 857                                         struct nvmem_layout *layout)
 858 {
 859         struct device_node __maybe_unused *layout_np;
 860         const struct of_device_id *match;
 861
 862         layout_np = of_nvmem_layout_get_container(nvmem);
 863         match = of_match_node(layout->of_match_table, layout_np);
 864
 865         return match ? match->data : NULL;
 866 }
 867 EXPORT_SYMBOL_GPL(nvmem_layout_get_match_data);
 868
 869 /**
 870  * nvmem_register() - Register a nvmem device for given nvmem_config.
 871  * Also creates a binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
 872  *
 873  * @config: nvmem device configuration with which nvmem device is created.
 874  *
 875  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
 876  * on success.
 877  */
 878
 879 struct nvmem_device *nvmem_register(const struct nvmem_config *config)
 880 {
 881         struct nvmem_device *nvmem;
 882         int rval;
 883
 884         if (!config->dev)
 885                 return ERR_PTR(-EINVAL);
 886
 887         if (!config->reg_read && !config->reg_write)
 888                 return ERR_PTR(-EINVAL);
 889
 890         nvmem = kzalloc(sizeof(*nvmem), GFP_KERNEL);
 891         if (!nvmem)
 892                 return ERR_PTR(-ENOMEM);
 893
 894         rval = ida_alloc(&nvmem_ida, GFP_KERNEL);
 895         if (rval < 0) {
 896                 kfree(nvmem);
 897                 return ERR_PTR(rval);
 898         }
 899
 900         nvmem->id = rval;
 901
 902         nvmem->dev.type = &nvmem_provider_type;
 903         nvmem->dev.bus = &nvmem_bus_type;
 904         nvmem->dev.parent = config->dev;
 905
 906         device_initialize(&nvmem->dev);
 907
 908         if (!config->ignore_wp)
 909                 nvmem->wp_gpio = gpiod_get_optional(config->dev, "wp",
 910                                                     GPIOD_OUT_HIGH);
 911         if (IS_ERR(nvmem->wp_gpio)) {
 912                 rval = PTR_ERR(nvmem->wp_gpio);
 913                 nvmem->wp_gpio = NULL;
 914                 goto err_put_device;
 915         }
 916
 917         kref_init(&nvmem->refcnt);
 918         INIT_LIST_HEAD(&nvmem->cells);
 919
 920         nvmem->owner = config->owner;
 921         if (!nvmem->owner && config->dev->driver)
 922                 nvmem->owner = config->dev->driver->owner;
 923         nvmem->stride = config->stride ?: 1;
 924         nvmem->word_size = config->word_size ?: 1;
 925         nvmem->size = config->size;
 926         nvmem->root_only = config->root_only;
 927         nvmem->priv = config->priv;
 928         nvmem->type = config->type;
 929         nvmem->reg_read = config->reg_read;
 930         nvmem->reg_write = config->reg_write;
 931         nvmem->keepout = config->keepout;
 932         nvmem->nkeepout = config->nkeepout;
 933         if (config->of_node)
 934                 nvmem->dev.of_node = config->of_node;
 935         else if (!config->no_of_node)
 936                 nvmem->dev.of_node = config->dev->of_node;
 937
 938         switch (config->id) {
 939         case NVMEM_DEVID_NONE:
 940                 rval = dev_set_name(&nvmem->dev, "%s", config->name);
 941                 break;
 942         case NVMEM_DEVID_AUTO:
 943                 rval = dev_set_name(&nvmem->dev, "%s%d", config->name, nvmem->id);
 944                 break;
 945         default:
 946                 rval = dev_set_name(&nvmem->dev, "%s%d",
 947                              config->name ? : "nvmem",
 948                              config->name ? config->id : nvmem->id);
 949                 break;
 950         }
 951
 952         if (rval)
 953                 goto err_put_device;
 954
 955         nvmem->read_only = device_property_present(config->dev, "read-only") ||
 956                            config->read_only || !nvmem->reg_write;
 957
 958 #ifdef CONFIG_NVMEM_SYSFS
 959         nvmem->dev.groups = nvmem_dev_groups;
 960 #endif
 961
 962         if (nvmem->nkeepout) {
 963                 rval = nvmem_validate_keepouts(nvmem);
 964                 if (rval)
 965                         goto err_put_device;
 966         }
 967
 968         if (config->compat) {
 969                 rval = nvmem_sysfs_setup_compat(nvmem, config);
 970                 if (rval)
 971                         goto err_put_device;
 972         }
 973
 974         /*
 975          * If the driver supplied a layout by config->layout, the module
 976          * pointer will be NULL and nvmem_layout_put() will be a noop.
 977          */
 978         nvmem->layout = config->layout ?: nvmem_layout_get(nvmem);
 979         if (IS_ERR(nvmem->layout)) {
 980                 rval = PTR_ERR(nvmem->layout);
 981                 nvmem->layout = NULL;
 982
 983                 if (rval == -EPROBE_DEFER)
 984                         goto err_teardown_compat;
 985         }
 986
 987         if (config->cells) {
 988                 rval = nvmem_add_cells(nvmem, config->cells, config->ncells);
 989                 if (rval)
 990                         goto err_remove_cells;
 991         }
 992
 993         rval = nvmem_add_cells_from_table(nvmem);
 994         if (rval)
 995                 goto err_remove_cells;
 996
 997         rval = nvmem_add_cells_from_legacy_of(nvmem);
 998         if (rval)
 999                 goto err_remove_cells;
1000
1001         dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
1002
1003         rval = device_add(&nvmem->dev);
1004         if (rval)
1005                 goto err_remove_cells;
1006
1007         rval = nvmem_add_cells_from_fixed_layout(nvmem);
1008         if (rval)
1009                 goto err_remove_cells;
1010
1011         rval = nvmem_add_cells_from_layout(nvmem);
1012         if (rval)
1013                 goto err_remove_cells;
1014
1015         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem);
1016
1017         return nvmem;
1018
1019 err_remove_cells:
1020         nvmem_device_remove_all_cells(nvmem);
1021         nvmem_layout_put(nvmem->layout);
1022 err_teardown_compat:
1023         if (config->compat)
1024                 nvmem_sysfs_remove_compat(nvmem, config);
1025 err_put_device:
1026         put_device(&nvmem->dev);
1027
1028         return ERR_PTR(rval);
1029 }
1030 EXPORT_SYMBOL_GPL(nvmem_register);
1031
1032 static void nvmem_device_release(struct kref *kref)
1033 {
1034         struct nvmem_device *nvmem;
1035
1036         nvmem = container_of(kref, struct nvmem_device, refcnt);
1037
1038         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_REMOVE, nvmem);
1039
1040         if (nvmem->flags & FLAG_COMPAT)
1041                 device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
1042
1043         nvmem_device_remove_all_cells(nvmem);
1044         nvmem_layout_put(nvmem->layout);
1045         device_unregister(&nvmem->dev);
1046 }
1047
1048 /**
1049  * nvmem_unregister() - Unregister previously registered nvmem device
1050  *
1051  * @nvmem: Pointer to previously registered nvmem device.
1052  */
1053 void nvmem_unregister(struct nvmem_device *nvmem)
1054 {
1055         if (nvmem)
1056                 kref_put(&nvmem->refcnt, nvmem_device_release);
1057 }
1058 EXPORT_SYMBOL_GPL(nvmem_unregister);
1059
1060 static void devm_nvmem_unregister(void *nvmem)
1061 {
1062         nvmem_unregister(nvmem);
1063 }
1064
1065 /**
1066  * devm_nvmem_register() - Register a managed nvmem device for given
1067  * nvmem_config.
1068  * Also creates a binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
1069  *
1070  * @dev: Device that uses the nvmem device.
1071  * @config: nvmem device configuration with which nvmem device is created.
1072  *
1073  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
1074  * on success.
1075  */
1076 struct nvmem_device *devm_nvmem_register(struct device *dev,
1077                                          const struct nvmem_config *config)
1078 {
1079         struct nvmem_device *nvmem;
1080         int ret;
1081
1082         nvmem = nvmem_register(config);
1083         if (IS_ERR(nvmem))
1084                 return nvmem;
1085
1086         ret = devm_add_action_or_reset(dev, devm_nvmem_unregister, nvmem);
1087         if (ret)
1088                 return ERR_PTR(ret);
1089
1090         return nvmem;
1091 }
1092 EXPORT_SYMBOL_GPL(devm_nvmem_register);
1093
1094 static struct nvmem_device *__nvmem_device_get(void *data,
1095                         int (*match)(struct device *dev, const void *data))
1096 {
1097         struct nvmem_device *nvmem = NULL;
1098         struct device *dev;
1099
1100         mutex_lock(&nvmem_mutex);
1101         dev = bus_find_device(&nvmem_bus_type, NULL, data, match);
1102         if (dev)
1103                 nvmem = to_nvmem_device(dev);
1104         mutex_unlock(&nvmem_mutex);
1105         if (!nvmem)
1106                 return ERR_PTR(-EPROBE_DEFER);
1107
1108         if (!try_module_get(nvmem->owner)) {
1109                 dev_err(&nvmem->dev,
1110                         "could not increase module refcount for cell %s\n",
1111                         nvmem_dev_name(nvmem));
1112
1113                 put_device(&nvmem->dev);
1114                 return ERR_PTR(-EINVAL);
1115         }
1116
1117         kref_get(&nvmem->refcnt);
1118
1119         return nvmem;
1120 }
1121
1122 static void __nvmem_device_put(struct nvmem_device *nvmem)
1123 {
1124         put_device(&nvmem->dev);
1125         module_put(nvmem->owner);
1126         kref_put(&nvmem->refcnt, nvmem_device_release);
1127 }
1128
1129 #if IS_ENABLED(CONFIG_OF)
1130 /**
1131  * of_nvmem_device_get() - Get nvmem device from a given id
1132  *
1133  * @np: Device tree node that uses the nvmem device.
1134  * @id: nvmem name from nvmem-names property.
1135  *
1136  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1137  * on success.
1138  */
1139 struct nvmem_device *of_nvmem_device_get(struct device_node *np, const char *id)
1140 {
1141
1142         struct device_node *nvmem_np;
1143         struct nvmem_device *nvmem;
1144         int index = 0;
1145
1146         if (id)
1147                 index = of_property_match_string(np, "nvmem-names", id);
1148
1149         nvmem_np = of_parse_phandle(np, "nvmem", index);
1150         if (!nvmem_np)
1151                 return ERR_PTR(-ENOENT);
1152
1153         nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
1154         of_node_put(nvmem_np);
1155         return nvmem;
1156 }
1157 EXPORT_SYMBOL_GPL(of_nvmem_device_get);
1158 #endif
1159
1160 /**
1161  * nvmem_device_get() - Get nvmem device from a given id
1162  *
1163  * @dev: Device that uses the nvmem device.
1164  * @dev_name: name of the requested nvmem device.
1165  *
1166  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1167  * on success.
1168  */
1169 struct nvmem_device *nvmem_device_get(struct device *dev, const char *dev_name)
1170 {
1171         if (dev->of_node) { /* try dt first */
1172                 struct nvmem_device *nvmem;
1173
1174                 nvmem = of_nvmem_device_get(dev->of_node, dev_name);
1175
1176                 if (!IS_ERR(nvmem) || PTR_ERR(nvmem) == -EPROBE_DEFER)
1177                         return nvmem;
1178
1179         }
1180
1181         return __nvmem_device_get((void *)dev_name, device_match_name);
1182 }
1183 EXPORT_SYMBOL_GPL(nvmem_device_get);
1184
1185 /**
1186  * nvmem_device_find() - Find nvmem device with matching function
1187  *
1188  * @data: Data to pass to match function
1189  * @match: Callback function to check device
1190  *
1191  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1192  * on success.
1193  */
1194 struct nvmem_device *nvmem_device_find(void *data,
1195                         int (*match)(struct device *dev, const void *data))
1196 {
1197         return __nvmem_device_get(data, match);
1198 }
1199 EXPORT_SYMBOL_GPL(nvmem_device_find);
1200
1201 static int devm_nvmem_device_match(struct device *dev, void *res, void *data)
1202 {
1203         struct nvmem_device **nvmem = res;
1204
1205         if (WARN_ON(!nvmem || !*nvmem))
1206                 return 0;
1207
1208         return *nvmem == data;
1209 }
1210
1211 static void devm_nvmem_device_release(struct device *dev, void *res)
1212 {
1213         nvmem_device_put(*(struct nvmem_device **)res);
1214 }
1215
1216 /**
1217  * devm_nvmem_device_put() - put alredy got nvmem device
1218  *
1219  * @dev: Device that uses the nvmem device.
1220  * @nvmem: pointer to nvmem device allocated by devm_nvmem_cell_get(),
1221  * that needs to be released.
1222  */
1223 void devm_nvmem_device_put(struct device *dev, struct nvmem_device *nvmem)
1224 {
1225         int ret;
1226
1227         ret = devres_release(dev, devm_nvmem_device_release,
1228                              devm_nvmem_device_match, nvmem);
1229
1230         WARN_ON(ret);
1231 }
1232 EXPORT_SYMBOL_GPL(devm_nvmem_device_put);
1233
1234 /**
1235  * nvmem_device_put() - put alredy got nvmem device
1236  *
1237  * @nvmem: pointer to nvmem device that needs to be released.
1238  */
1239 void nvmem_device_put(struct nvmem_device *nvmem)
1240 {
1241         __nvmem_device_put(nvmem);
1242 }
1243 EXPORT_SYMBOL_GPL(nvmem_device_put);
1244
1245 /**
1246  * devm_nvmem_device_get() - Get nvmem cell of device form a given id
1247  *
1248  * @dev: Device that requests the nvmem device.
1249  * @id: name id for the requested nvmem device.
1250  *
1251  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_cell
1252  * on success.  The nvmem_cell will be freed by the automatically once the
1253  * device is freed.
1254  */
1255 struct nvmem_device *devm_nvmem_device_get(struct device *dev, const char *id)
1256 {
1257         struct nvmem_device **ptr, *nvmem;
1258
1259         ptr = devres_alloc(devm_nvmem_device_release, sizeof(*ptr), GFP_KERNEL);
1260         if (!ptr)
1261                 return ERR_PTR(-ENOMEM);
1262
1263         nvmem = nvmem_device_get(dev, id);
1264         if (!IS_ERR(nvmem)) {
1265                 *ptr = nvmem;
1266                 devres_add(dev, ptr);
1267         } else {
1268                 devres_free(ptr);
1269         }
1270
1271         return nvmem;
1272 }
1273 EXPORT_SYMBOL_GPL(devm_nvmem_device_get);
1274
1275 static struct nvmem_cell *nvmem_create_cell(struct nvmem_cell_entry *entry,
1276                                             const char *id, int index)
1277 {
1278         struct nvmem_cell *cell;
1279         const char *name = NULL;
1280
1281         cell = kzalloc(sizeof(*cell), GFP_KERNEL);
1282         if (!cell)
1283                 return ERR_PTR(-ENOMEM);
1284
1285         if (id) {
1286                 name = kstrdup_const(id, GFP_KERNEL);
1287                 if (!name) {
1288                         kfree(cell);
1289                         return ERR_PTR(-ENOMEM);
1290                 }
1291         }
1292
1293         cell->id = name;
1294         cell->entry = entry;
1295         cell->index = index;
1296
1297         return cell;
1298 }
1299
1300 static struct nvmem_cell *
1301 nvmem_cell_get_from_lookup(struct device *dev, const char *con_id)
1302 {
1303         struct nvmem_cell_entry *cell_entry;
1304         struct nvmem_cell *cell = ERR_PTR(-ENOENT);
1305         struct nvmem_cell_lookup *lookup;
1306         struct nvmem_device *nvmem;
1307         const char *dev_id;
1308
1309         if (!dev)
1310                 return ERR_PTR(-EINVAL);
1311
1312         dev_id = dev_name(dev);
1313
1314         mutex_lock(&nvmem_lookup_mutex);
1315
1316         list_for_each_entry(lookup, &nvmem_lookup_list, node) {
1317                 if ((strcmp(lookup->dev_id, dev_id) == 0) &&
1318                     (strcmp(lookup->con_id, con_id) == 0)) {
1319                         /* This is the right entry. */
1320                         nvmem = __nvmem_device_get((void *)lookup->nvmem_name,
1321                                                    device_match_name);
1322                         if (IS_ERR(nvmem)) {
1323                                 /* Provider may not be registered yet. */
1324                                 cell = ERR_CAST(nvmem);
1325                                 break;
1326                         }
1327
1328                         cell_entry = nvmem_find_cell_entry_by_name(nvmem,
1329                                                                    lookup->cell_name);
1330                         if (!cell_entry) {
1331                                 __nvmem_device_put(nvmem);
1332                                 cell = ERR_PTR(-ENOENT);
1333                         } else {
1334                                 cell = nvmem_create_cell(cell_entry, con_id, 0);
1335                                 if (IS_ERR(cell))
1336                                         __nvmem_device_put(nvmem);
1337                         }
1338                         break;
1339                 }
1340         }
1341
1342         mutex_unlock(&nvmem_lookup_mutex);
1343         return cell;
1344 }
1345
1346 #if IS_ENABLED(CONFIG_OF)
1347 static struct nvmem_cell_entry *
1348 nvmem_find_cell_entry_by_node(struct nvmem_device *nvmem, struct device_node *np)
1349 {
1350         struct nvmem_cell_entry *iter, *cell = NULL;
1351
1352         mutex_lock(&nvmem_mutex);
1353         list_for_each_entry(iter, &nvmem->cells, node) {
1354                 if (np == iter->np) {
1355                         cell = iter;
1356                         break;
1357                 }
1358         }
1359         mutex_unlock(&nvmem_mutex);
1360
1361         return cell;
1362 }
1363
1364 /**
1365  * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
1366  *
1367  * @np: Device tree node that uses the nvmem cell.
1368  * @id: nvmem cell name from nvmem-cell-names property, or NULL
1369  *      for the cell at index 0 (the lone cell with no accompanying
1370  *      nvmem-cell-names property).
1371  *
1372  * Return: Will be an ERR_PTR() on error or a valid pointer
1373  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1374  * nvmem_cell_put().
1375  */
1376 struct nvmem_cell *of_nvmem_cell_get(struct device_node *np, const char *id)
1377 {
1378         struct device_node *cell_np, *nvmem_np;
1379         struct nvmem_device *nvmem;
1380         struct nvmem_cell_entry *cell_entry;
1381         struct nvmem_cell *cell;
1382         struct of_phandle_args cell_spec;
1383         int index = 0;
1384         int cell_index = 0;
1385         int ret;
1386
1387         /* if cell name exists, find index to the name */
1388         if (id)
1389                 index = of_property_match_string(np, "nvmem-cell-names", id);
1390
1391         ret = of_parse_phandle_with_optional_args(np, "nvmem-cells",
1392                                                   "#nvmem-cell-cells",
1393                                                   index, &cell_spec);
1394         if (ret)
1395                 return ERR_PTR(-ENOENT);
1396
1397         if (cell_spec.args_count > 1)
1398                 return ERR_PTR(-EINVAL);
1399
1400         cell_np = cell_spec.np;
1401         if (cell_spec.args_count)
1402                 cell_index = cell_spec.args[0];
1403
1404         nvmem_np = of_get_parent(cell_np);
1405         if (!nvmem_np) {
1406                 of_node_put(cell_np);
1407                 return ERR_PTR(-EINVAL);
1408         }
1409
1410         /* nvmem layouts produce cells within the nvmem-layout container */
1411         if (of_node_name_eq(nvmem_np, "nvmem-layout")) {
1412                 nvmem_np = of_get_next_parent(nvmem_np);
1413                 if (!nvmem_np) {
1414                         of_node_put(cell_np);
1415                         return ERR_PTR(-EINVAL);
1416                 }
1417         }
1418
1419         nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
1420         of_node_put(nvmem_np);
1421         if (IS_ERR(nvmem)) {
1422                 of_node_put(cell_np);
1423                 return ERR_CAST(nvmem);
1424         }
1425
1426         cell_entry = nvmem_find_cell_entry_by_node(nvmem, cell_np);
1427         of_node_put(cell_np);
1428         if (!cell_entry) {
1429                 __nvmem_device_put(nvmem);
1430                 return ERR_PTR(-ENOENT);
1431         }
1432
1433         cell = nvmem_create_cell(cell_entry, id, cell_index);
1434         if (IS_ERR(cell))
1435                 __nvmem_device_put(nvmem);
1436
1437         return cell;
1438 }
1439 EXPORT_SYMBOL_GPL(of_nvmem_cell_get);
1440 #endif
1441
1442 /**
1443  * nvmem_cell_get() - Get nvmem cell of device form a given cell name
1444  *
1445  * @dev: Device that requests the nvmem cell.
1446  * @id: nvmem cell name to get (this corresponds with the name from the
1447  *      nvmem-cell-names property for DT systems and with the con_id from
1448  *      the lookup entry for non-DT systems).
1449  *
1450  * Return: Will be an ERR_PTR() on error or a valid pointer
1451  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1452  * nvmem_cell_put().
1453  */
1454 struct nvmem_cell *nvmem_cell_get(struct device *dev, const char *id)
1455 {
1456         struct nvmem_cell *cell;
1457
1458         if (dev->of_node) { /* try dt first */
1459                 cell = of_nvmem_cell_get(dev->of_node, id);
1460                 if (!IS_ERR(cell) || PTR_ERR(cell) == -EPROBE_DEFER)
1461                         return cell;
1462         }
1463
1464         /* NULL cell id only allowed for device tree; invalid otherwise */
1465         if (!id)
1466                 return ERR_PTR(-EINVAL);
1467
1468         return nvmem_cell_get_from_lookup(dev, id);
1469 }
1470 EXPORT_SYMBOL_GPL(nvmem_cell_get);
1471
1472 static void devm_nvmem_cell_release(struct device *dev, void *res)
1473 {
1474         nvmem_cell_put(*(struct nvmem_cell **)res);
1475 }
1476
1477 /**
1478  * devm_nvmem_cell_get() - Get nvmem cell of device form a given id
1479  *
1480  * @dev: Device that requests the nvmem cell.
1481  * @id: nvmem cell name id to get.
1482  *
1483  * Return: Will be an ERR_PTR() on error or a valid pointer
1484  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1485  * automatically once the device is freed.
1486  */
1487 struct nvmem_cell *devm_nvmem_cell_get(struct device *dev, const char *id)
1488 {
1489         struct nvmem_cell **ptr, *cell;
1490
1491         ptr = devres_alloc(devm_nvmem_cell_release, sizeof(*ptr), GFP_KERNEL);
1492         if (!ptr)
1493                 return ERR_PTR(-ENOMEM);
1494
1495         cell = nvmem_cell_get(dev, id);
1496         if (!IS_ERR(cell)) {
1497                 *ptr = cell;
1498                 devres_add(dev, ptr);
1499         } else {
1500                 devres_free(ptr);
1501         }
1502
1503         return cell;
1504 }
1505 EXPORT_SYMBOL_GPL(devm_nvmem_cell_get);
1506
1507 static int devm_nvmem_cell_match(struct device *dev, void *res, void *data)
1508 {
1509         struct nvmem_cell **c = res;
1510
1511         if (WARN_ON(!c || !*c))
1512                 return 0;
1513
1514         return *c == data;
1515 }
1516
1517 /**
1518  * devm_nvmem_cell_put() - Release previously allocated nvmem cell
1519  * from devm_nvmem_cell_get.
1520  *
1521  * @dev: Device that requests the nvmem cell.
1522  * @cell: Previously allocated nvmem cell by devm_nvmem_cell_get().
1523  */
1524 void devm_nvmem_cell_put(struct device *dev, struct nvmem_cell *cell)
1525 {
1526         int ret;
1527
1528         ret = devres_release(dev, devm_nvmem_cell_release,
1529                                 devm_nvmem_cell_match, cell);
1530
1531         WARN_ON(ret);
1532 }
1533 EXPORT_SYMBOL(devm_nvmem_cell_put);
1534
1535 /**
1536  * nvmem_cell_put() - Release previously allocated nvmem cell.
1537  *
1538  * @cell: Previously allocated nvmem cell by nvmem_cell_get().
1539  */
1540 void nvmem_cell_put(struct nvmem_cell *cell)
1541 {
1542         struct nvmem_device *nvmem = cell->entry->nvmem;
1543
1544         if (cell->id)
1545                 kfree_const(cell->id);
1546
1547         kfree(cell);
1548         __nvmem_device_put(nvmem);
1549 }
1550 EXPORT_SYMBOL_GPL(nvmem_cell_put);
1551
1552 static void nvmem_shift_read_buffer_in_place(struct nvmem_cell_entry *cell, void *buf)
1553 {
1554         u8 *p, *b;
1555         int i, extra, bit_offset = cell->bit_offset;
1556
1557         p = b = buf;
1558         if (bit_offset) {
1559                 /* First shift */
1560                 *b++ >>= bit_offset;
1561
1562                 /* setup rest of the bytes if any */
1563                 for (i = 1; i < cell->bytes; i++) {
1564                         /* Get bits from next byte and shift them towards msb */
1565                         *p |= *b << (BITS_PER_BYTE - bit_offset);
1566
1567                         p = b;
1568                         *b++ >>= bit_offset;
1569                 }
1570         } else {
1571                 /* point to the msb */
1572                 p += cell->bytes - 1;
1573         }
1574
1575         /* result fits in less bytes */
1576         extra = cell->bytes - DIV_ROUND_UP(cell->nbits, BITS_PER_BYTE);
1577         while (--extra >= 0)
1578                 *p-- = 0;
1579
1580         /* clear msb bits if any leftover in the last byte */
1581         if (cell->nbits % BITS_PER_BYTE)
1582                 *p &= GENMASK((cell->nbits % BITS_PER_BYTE) - 1, 0);
1583 }
1584
1585 static int __nvmem_cell_read(struct nvmem_device *nvmem,
1586                              struct nvmem_cell_entry *cell,
1587                              void *buf, size_t *len, const char *id, int index)
1588 {
1589         int rc;
1590
1591         rc = nvmem_reg_read(nvmem, cell->offset, buf, cell->raw_len);
1592
1593         if (rc)
1594                 return rc;
1595
1596         /* shift bits in-place */
1597         if (cell->bit_offset || cell->nbits)
1598                 nvmem_shift_read_buffer_in_place(cell, buf);
1599
1600         if (cell->read_post_process) {
1601                 rc = cell->read_post_process(cell->priv, id, index,
1602                                              cell->offset, buf, cell->raw_len);
1603                 if (rc)
1604                         return rc;
1605         }
1606
1607         if (len)
1608                 *len = cell->bytes;
1609
1610         return 0;
1611 }
1612
1613 /**
1614  * nvmem_cell_read() - Read a given nvmem cell
1615  *
1616  * @cell: nvmem cell to be read.
1617  * @len: pointer to length of cell which will be populated on successful read;
1618  *       can be NULL.
1619  *
1620  * Return: ERR_PTR() on error or a valid pointer to a buffer on success. The
1621  * buffer should be freed by the consumer with a kfree().
1622  */
1623 void *nvmem_cell_read(struct nvmem_cell *cell, size_t *len)
1624 {
1625         struct nvmem_cell_entry *entry = cell->entry;
1626         struct nvmem_device *nvmem = entry->nvmem;
1627         u8 *buf;
1628         int rc;
1629
1630         if (!nvmem)
1631                 return ERR_PTR(-EINVAL);
1632
1633         buf = kzalloc(max_t(size_t, entry->raw_len, entry->bytes), GFP_KERNEL);
1634         if (!buf)
1635                 return ERR_PTR(-ENOMEM);
1636
1637         rc = __nvmem_cell_read(nvmem, cell->entry, buf, len, cell->id, cell->index);
1638         if (rc) {
1639                 kfree(buf);
1640                 return ERR_PTR(rc);
1641         }
1642
1643         return buf;
1644 }
1645 EXPORT_SYMBOL_GPL(nvmem_cell_read);
1646
1647 static void *nvmem_cell_prepare_write_buffer(struct nvmem_cell_entry *cell,
1648                                              u8 *_buf, int len)
1649 {
1650         struct nvmem_device *nvmem = cell->nvmem;
1651         int i, rc, nbits, bit_offset = cell->bit_offset;
1652         u8 v, *p, *buf, *b, pbyte, pbits;
1653
1654         nbits = cell->nbits;
1655         buf = kzalloc(cell->bytes, GFP_KERNEL);
1656         if (!buf)
1657                 return ERR_PTR(-ENOMEM);
1658
1659         memcpy(buf, _buf, len);
1660         p = b = buf;
1661
1662         if (bit_offset) {
1663                 pbyte = *b;
1664                 *b <<= bit_offset;
1665
1666                 /* setup the first byte with lsb bits from nvmem */
1667                 rc = nvmem_reg_read(nvmem, cell->offset, &v, 1);
1668                 if (rc)
1669                         goto err;
1670                 *b++ |= GENMASK(bit_offset - 1, 0) & v;
1671
1672                 /* setup rest of the byte if any */
1673                 for (i = 1; i < cell->bytes; i++) {
1674                         /* Get last byte bits and shift them towards lsb */
1675                         pbits = pbyte >> (BITS_PER_BYTE - 1 - bit_offset);
1676                         pbyte = *b;
1677                         p = b;
1678                         *b <<= bit_offset;
1679                         *b++ |= pbits;
1680                 }
1681         }
1682
1683         /* if it's not end on byte boundary */
1684         if ((nbits + bit_offset) % BITS_PER_BYTE) {
1685                 /* setup the last byte with msb bits from nvmem */
1686                 rc = nvmem_reg_read(nvmem,
1687                                     cell->offset + cell->bytes - 1, &v, 1);
1688                 if (rc)
1689                         goto err;
1690                 *p |= GENMASK(7, (nbits + bit_offset) % BITS_PER_BYTE) & v;
1691
1692         }
1693
1694         return buf;
1695 err:
1696         kfree(buf);
1697         return ERR_PTR(rc);
1698 }
1699
1700 static int __nvmem_cell_entry_write(struct nvmem_cell_entry *cell, void *buf, size_t len)
1701 {
1702         struct nvmem_device *nvmem = cell->nvmem;
1703         int rc;
1704
1705         if (!nvmem || nvmem->read_only ||
1706             (cell->bit_offset == 0 && len != cell->bytes))
1707                 return -EINVAL;
1708
1709         /*
1710          * Any cells which have a read_post_process hook are read-only because
1711          * we cannot reverse the operation and it might affect other cells,
1712          * too.
1713          */
1714         if (cell->read_post_process)
1715                 return -EINVAL;
1716
1717         if (cell->bit_offset || cell->nbits) {
1718                 buf = nvmem_cell_prepare_write_buffer(cell, buf, len);
1719                 if (IS_ERR(buf))
1720                         return PTR_ERR(buf);
1721         }
1722
1723         rc = nvmem_reg_write(nvmem, cell->offset, buf, cell->bytes);
1724
1725         /* free the tmp buffer */
1726         if (cell->bit_offset || cell->nbits)
1727                 kfree(buf);
1728
1729         if (rc)
1730                 return rc;
1731
1732         return len;
1733 }
1734
1735 /**
1736  * nvmem_cell_write() - Write to a given nvmem cell
1737  *
1738  * @cell: nvmem cell to be written.
1739  * @buf: Buffer to be written.
1740  * @len: length of buffer to be written to nvmem cell.
1741  *
1742  * Return: length of bytes written or negative on failure.
1743  */
1744 int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len)
1745 {
1746         return __nvmem_cell_entry_write(cell->entry, buf, len);
1747 }
1748
1749 EXPORT_SYMBOL_GPL(nvmem_cell_write);
1750
1751 static int nvmem_cell_read_common(struct device *dev, const char *cell_id,
1752                                   void *val, size_t count)
1753 {
1754         struct nvmem_cell *cell;
1755         void *buf;
1756         size_t len;
1757
1758         cell = nvmem_cell_get(dev, cell_id);
1759         if (IS_ERR(cell))
1760                 return PTR_ERR(cell);
1761
1762         buf = nvmem_cell_read(cell, &len);
1763         if (IS_ERR(buf)) {
1764                 nvmem_cell_put(cell);
1765                 return PTR_ERR(buf);
1766         }
1767         if (len != count) {
1768                 kfree(buf);
1769                 nvmem_cell_put(cell);
1770                 return -EINVAL;
1771         }
1772         memcpy(val, buf, count);
1773         kfree(buf);
1774         nvmem_cell_put(cell);
1775
1776         return 0;
1777 }
1778
1779 /**
1780  * nvmem_cell_read_u8() - Read a cell value as a u8
1781  *
1782  * @dev: Device that requests the nvmem cell.
1783  * @cell_id: Name of nvmem cell to read.
1784  * @val: pointer to output value.
1785  *
1786  * Return: 0 on success or negative errno.
1787  */
1788 int nvmem_cell_read_u8(struct device *dev, const char *cell_id, u8 *val)
1789 {
1790         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1791 }
1792 EXPORT_SYMBOL_GPL(nvmem_cell_read_u8);
1793
1794 /**
1795  * nvmem_cell_read_u16() - Read a cell value as a u16
1796  *
1797  * @dev: Device that requests the nvmem cell.
1798  * @cell_id: Name of nvmem cell to read.
1799  * @val: pointer to output value.
1800  *
1801  * Return: 0 on success or negative errno.
1802  */
1803 int nvmem_cell_read_u16(struct device *dev, const char *cell_id, u16 *val)
1804 {
1805         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1806 }
1807 EXPORT_SYMBOL_GPL(nvmem_cell_read_u16);
1808
1809 /**
1810  * nvmem_cell_read_u32() - Read a cell value as a u32
1811  *
1812  * @dev: Device that requests the nvmem cell.
1813  * @cell_id: Name of nvmem cell to read.
1814  * @val: pointer to output value.
1815  *
1816  * Return: 0 on success or negative errno.
1817  */
1818 int nvmem_cell_read_u32(struct device *dev, const char *cell_id, u32 *val)
1819 {
1820         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1821 }
1822 EXPORT_SYMBOL_GPL(nvmem_cell_read_u32);
1823
1824 /**
1825  * nvmem_cell_read_u64() - Read a cell value as a u64
1826  *
1827  * @dev: Device that requests the nvmem cell.
1828  * @cell_id: Name of nvmem cell to read.
1829  * @val: pointer to output value.
1830  *
1831  * Return: 0 on success or negative errno.
1832  */
1833 int nvmem_cell_read_u64(struct device *dev, const char *cell_id, u64 *val)
1834 {
1835         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1836 }
1837 EXPORT_SYMBOL_GPL(nvmem_cell_read_u64);
1838
1839 static const void *nvmem_cell_read_variable_common(struct device *dev,
1840                                                    const char *cell_id,
1841                                                    size_t max_len, size_t *len)
1842 {
1843         struct nvmem_cell *cell;
1844         int nbits;
1845         void *buf;
1846
1847         cell = nvmem_cell_get(dev, cell_id);
1848         if (IS_ERR(cell))
1849                 return cell;
1850
1851         nbits = cell->entry->nbits;
1852         buf = nvmem_cell_read(cell, len);
1853         nvmem_cell_put(cell);
1854         if (IS_ERR(buf))
1855                 return buf;
1856
1857         /*
1858          * If nbits is set then nvmem_cell_read() can significantly exaggerate
1859          * the length of the real data. Throw away the extra junk.
1860          */
1861         if (nbits)
1862                 *len = DIV_ROUND_UP(nbits, 8);
1863
1864         if (*len > max_len) {
1865                 kfree(buf);
1866                 return ERR_PTR(-ERANGE);
1867         }
1868
1869         return buf;
1870 }
1871
1872 /**
1873  * nvmem_cell_read_variable_le_u32() - Read up to 32-bits of data as a little endian number.
1874  *
1875  * @dev: Device that requests the nvmem cell.
1876  * @cell_id: Name of nvmem cell to read.
1877  * @val: pointer to output value.
1878  *
1879  * Return: 0 on success or negative errno.
1880  */
1881 int nvmem_cell_read_variable_le_u32(struct device *dev, const char *cell_id,
1882                                     u32 *val)
1883 {
1884         size_t len;
1885         const u8 *buf;
1886         int i;
1887
1888         buf = nvmem_cell_read_variable_common(dev, cell_id, sizeof(*val), &len);
1889         if (IS_ERR(buf))
1890                 return PTR_ERR(buf);
1891
1892         /* Copy w/ implicit endian conversion */
1893         *val = 0;
1894         for (i = 0; i < len; i++)
1895                 *val |= buf[i] << (8 * i);
1896
1897         kfree(buf);
1898
1899         return 0;
1900 }
1901 EXPORT_SYMBOL_GPL(nvmem_cell_read_variable_le_u32);
1902
1903 /**
1904  * nvmem_cell_read_variable_le_u64() - Read up to 64-bits of data as a little endian number.
1905  *
1906  * @dev: Device that requests the nvmem cell.
1907  * @cell_id: Name of nvmem cell to read.
1908  * @val: pointer to output value.
1909  *
1910  * Return: 0 on success or negative errno.
1911  */
1912 int nvmem_cell_read_variable_le_u64(struct device *dev, const char *cell_id,
1913                                     u64 *val)
1914 {
1915         size_t len;
1916         const u8 *buf;
1917         int i;
1918
1919         buf = nvmem_cell_read_variable_common(dev, cell_id, sizeof(*val), &len);
1920         if (IS_ERR(buf))
1921                 return PTR_ERR(buf);
1922
1923         /* Copy w/ implicit endian conversion */
1924         *val = 0;
1925         for (i = 0; i < len; i++)
1926                 *val |= (uint64_t)buf[i] << (8 * i);
1927
1928         kfree(buf);
1929
1930         return 0;
1931 }
1932 EXPORT_SYMBOL_GPL(nvmem_cell_read_variable_le_u64);
1933
1934 /**
1935  * nvmem_device_cell_read() - Read a given nvmem device and cell
1936  *
1937  * @nvmem: nvmem device to read from.
1938  * @info: nvmem cell info to be read.
1939  * @buf: buffer pointer which will be populated on successful read.
1940  *
1941  * Return: length of successful bytes read on success and negative
1942  * error code on error.
1943  */
1944 ssize_t nvmem_device_cell_read(struct nvmem_device *nvmem,
1945                            struct nvmem_cell_info *info, void *buf)
1946 {
1947         struct nvmem_cell_entry cell;
1948         int rc;
1949         ssize_t len;
1950
1951         if (!nvmem)
1952                 return -EINVAL;
1953
1954         rc = nvmem_cell_info_to_nvmem_cell_entry_nodup(nvmem, info, &cell);
1955         if (rc)
1956                 return rc;
1957
1958         rc = __nvmem_cell_read(nvmem, &cell, buf, &len, NULL, 0);
1959         if (rc)
1960                 return rc;
1961
1962         return len;
1963 }
1964 EXPORT_SYMBOL_GPL(nvmem_device_cell_read);
1965
1966 /**
1967  * nvmem_device_cell_write() - Write cell to a given nvmem device
1968  *
1969  * @nvmem: nvmem device to be written to.
1970  * @info: nvmem cell info to be written.
1971  * @buf: buffer to be written to cell.
1972  *
1973  * Return: length of bytes written or negative error code on failure.
1974  */
1975 int nvmem_device_cell_write(struct nvmem_device *nvmem,
1976                             struct nvmem_cell_info *info, void *buf)
1977 {
1978         struct nvmem_cell_entry cell;
1979         int rc;
1980
1981         if (!nvmem)
1982                 return -EINVAL;
1983
1984         rc = nvmem_cell_info_to_nvmem_cell_entry_nodup(nvmem, info, &cell);
1985         if (rc)
1986                 return rc;
1987
1988         return __nvmem_cell_entry_write(&cell, buf, cell.bytes);
1989 }
1990 EXPORT_SYMBOL_GPL(nvmem_device_cell_write);
1991
1992 /**
1993  * nvmem_device_read() - Read from a given nvmem device
1994  *
1995  * @nvmem: nvmem device to read from.
1996  * @offset: offset in nvmem device.
1997  * @bytes: number of bytes to read.
1998  * @buf: buffer pointer which will be populated on successful read.
1999  *
2000  * Return: length of successful bytes read on success and negative
2001  * error code on error.
2002  */
2003 int nvmem_device_read(struct nvmem_device *nvmem,
2004                       unsigned int offset,
2005                       size_t bytes, void *buf)
2006 {
2007         int rc;
2008
2009         if (!nvmem)
2010                 return -EINVAL;
2011
2012         rc = nvmem_reg_read(nvmem, offset, buf, bytes);
2013
2014         if (rc)
2015                 return rc;
2016
2017         return bytes;
2018 }
2019 EXPORT_SYMBOL_GPL(nvmem_device_read);
2020
2021 /**
2022  * nvmem_device_write() - Write cell to a given nvmem device
2023  *
2024  * @nvmem: nvmem device to be written to.
2025  * @offset: offset in nvmem device.
2026  * @bytes: number of bytes to write.
2027  * @buf: buffer to be written.
2028  *
2029  * Return: length of bytes written or negative error code on failure.
2030  */
2031 int nvmem_device_write(struct nvmem_device *nvmem,
2032                        unsigned int offset,
2033                        size_t bytes, void *buf)
2034 {
2035         int rc;
2036
2037         if (!nvmem)
2038                 return -EINVAL;
2039
2040         rc = nvmem_reg_write(nvmem, offset, buf, bytes);
2041
2042         if (rc)
2043                 return rc;
2044
2045
2046         return bytes;
2047 }
2048 EXPORT_SYMBOL_GPL(nvmem_device_write);
2049
2050 /**
2051  * nvmem_add_cell_table() - register a table of cell info entries
2052  *
2053  * @table: table of cell info entries
2054  */
2055 void nvmem_add_cell_table(struct nvmem_cell_table *table)
2056 {
2057         mutex_lock(&nvmem_cell_mutex);
2058         list_add_tail(&table->node, &nvmem_cell_tables);
2059         mutex_unlock(&nvmem_cell_mutex);
2060 }
2061 EXPORT_SYMBOL_GPL(nvmem_add_cell_table);
2062
2063 /**
2064  * nvmem_del_cell_table() - remove a previously registered cell info table
2065  *
2066  * @table: table of cell info entries
2067  */
2068 void nvmem_del_cell_table(struct nvmem_cell_table *table)
2069 {
2070         mutex_lock(&nvmem_cell_mutex);
2071         list_del(&table->node);
2072         mutex_unlock(&nvmem_cell_mutex);
2073 }
2074 EXPORT_SYMBOL_GPL(nvmem_del_cell_table);
2075
2076 /**
2077  * nvmem_add_cell_lookups() - register a list of cell lookup entries
2078  *
2079  * @entries: array of cell lookup entries
2080  * @nentries: number of cell lookup entries in the array
2081  */
2082 void nvmem_add_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
2083 {
2084         int i;
2085
2086         mutex_lock(&nvmem_lookup_mutex);
2087         for (i = 0; i < nentries; i++)
2088                 list_add_tail(&entries[i].node, &nvmem_lookup_list);
2089         mutex_unlock(&nvmem_lookup_mutex);
2090 }
2091 EXPORT_SYMBOL_GPL(nvmem_add_cell_lookups);
2092
2093 /**
2094  * nvmem_del_cell_lookups() - remove a list of previously added cell lookup
2095  *                            entries
2096  *
2097  * @entries: array of cell lookup entries
2098  * @nentries: number of cell lookup entries in the array
2099  */
2100 void nvmem_del_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
2101 {
2102         int i;
2103
2104         mutex_lock(&nvmem_lookup_mutex);
2105         for (i = 0; i < nentries; i++)
2106                 list_del(&entries[i].node);
2107         mutex_unlock(&nvmem_lookup_mutex);
2108 }
2109 EXPORT_SYMBOL_GPL(nvmem_del_cell_lookups);
2110
2111 /**
2112  * nvmem_dev_name() - Get the name of a given nvmem device.
2113  *
2114  * @nvmem: nvmem device.
2115  *
2116  * Return: name of the nvmem device.
2117  */
2118 const char *nvmem_dev_name(struct nvmem_device *nvmem)
2119 {
2120         return dev_name(&nvmem->dev);
2121 }
2122 EXPORT_SYMBOL_GPL(nvmem_dev_name);
2123
2124 static int __init nvmem_init(void)
2125 {
2126         return bus_register(&nvmem_bus_type);
2127 }
2128
2129 static void __exit nvmem_exit(void)
2130 {
2131         bus_unregister(&nvmem_bus_type);
2132 }
2133
2134 subsys_initcall(nvmem_init);
2135 module_exit(nvmem_exit);
2136
2137 MODULE_AUTHOR("Srinivas Kandagatla <srinivas.kandagatla@linaro.org");
2138 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com");
2139 MODULE_DESCRIPTION("nvmem Driver Core");