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