drivers/nvmem/core.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * nvmem framework core.
   4  *
   5  * Copyright (C) 2015 Srinivas Kandagatla <[email protected]>
   6  * Copyright (C) 2013 Maxime Ripard <[email protected]>
   7  */
   8
   9 #include <linux/device.h>
  10 #include <linux/export.h>
  11 #include <linux/fs.h>
  12 #include <linux/idr.h>
  13 #include <linux/init.h>
  14 #include <linux/kref.h>
  15 #include <linux/module.h>
  16 #include <linux/nvmem-consumer.h>
  17 #include <linux/nvmem-provider.h>
  18 #include <linux/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         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_LAYOUT_ADD, layout);
 775
 776         return 0;
 777 }
 778 EXPORT_SYMBOL_GPL(__nvmem_layout_register);
 779
 780 void nvmem_layout_unregister(struct nvmem_layout *layout)
 781 {
 782         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_LAYOUT_REMOVE, layout);
 783
 784         spin_lock(&nvmem_layout_lock);
 785         list_del(&layout->node);
 786         spin_unlock(&nvmem_layout_lock);
 787 }
 788 EXPORT_SYMBOL_GPL(nvmem_layout_unregister);
 789
 790 static struct nvmem_layout *nvmem_layout_get(struct nvmem_device *nvmem)
 791 {
 792         struct device_node *layout_np;
 793         struct nvmem_layout *l, *layout = ERR_PTR(-EPROBE_DEFER);
 794
 795         layout_np = of_nvmem_layout_get_container(nvmem);
 796         if (!layout_np)
 797                 return NULL;
 798
 799         /*
 800          * In case the nvmem device was built-in while the layout was built as a
 801          * module, we shall manually request the layout driver loading otherwise
 802          * we'll never have any match.
 803          */
 804         of_request_module(layout_np);
 805
 806         spin_lock(&nvmem_layout_lock);
 807
 808         list_for_each_entry(l, &nvmem_layouts, node) {
 809                 if (of_match_node(l->of_match_table, layout_np)) {
 810                         if (try_module_get(l->owner))
 811                                 layout = l;
 812
 813                         break;
 814                 }
 815         }
 816
 817         spin_unlock(&nvmem_layout_lock);
 818         of_node_put(layout_np);
 819
 820         return layout;
 821 }
 822
 823 static void nvmem_layout_put(struct nvmem_layout *layout)
 824 {
 825         if (layout)
 826                 module_put(layout->owner);
 827 }
 828
 829 static int nvmem_add_cells_from_layout(struct nvmem_device *nvmem)
 830 {
 831         struct nvmem_layout *layout = nvmem->layout;
 832         int ret;
 833
 834         if (layout && layout->add_cells) {
 835                 ret = layout->add_cells(&nvmem->dev, nvmem, layout);
 836                 if (ret)
 837                         return ret;
 838         }
 839
 840         return 0;
 841 }
 842
 843 #if IS_ENABLED(CONFIG_OF)
 844 /**
 845  * of_nvmem_layout_get_container() - Get OF node to layout container.
 846  *
 847  * @nvmem: nvmem device.
 848  *
 849  * Return: a node pointer with refcount incremented or NULL if no
 850  * container exists. Use of_node_put() on it when done.
 851  */
 852 struct device_node *of_nvmem_layout_get_container(struct nvmem_device *nvmem)
 853 {
 854         return of_get_child_by_name(nvmem->dev.of_node, "nvmem-layout");
 855 }
 856 EXPORT_SYMBOL_GPL(of_nvmem_layout_get_container);
 857 #endif
 858
 859 const void *nvmem_layout_get_match_data(struct nvmem_device *nvmem,
 860                                         struct nvmem_layout *layout)
 861 {
 862         struct device_node __maybe_unused *layout_np;
 863         const struct of_device_id *match;
 864
 865         layout_np = of_nvmem_layout_get_container(nvmem);
 866         match = of_match_node(layout->of_match_table, layout_np);
 867
 868         return match ? match->data : NULL;
 869 }
 870 EXPORT_SYMBOL_GPL(nvmem_layout_get_match_data);
 871
 872 /**
 873  * nvmem_register() - Register a nvmem device for given nvmem_config.
 874  * Also creates a binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
 875  *
 876  * @config: nvmem device configuration with which nvmem device is created.
 877  *
 878  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
 879  * on success.
 880  */
 881
 882 struct nvmem_device *nvmem_register(const struct nvmem_config *config)
 883 {
 884         struct nvmem_device *nvmem;
 885         int rval;
 886
 887         if (!config->dev)
 888                 return ERR_PTR(-EINVAL);
 889
 890         if (!config->reg_read && !config->reg_write)
 891                 return ERR_PTR(-EINVAL);
 892
 893         nvmem = kzalloc(sizeof(*nvmem), GFP_KERNEL);
 894         if (!nvmem)
 895                 return ERR_PTR(-ENOMEM);
 896
 897         rval = ida_alloc(&nvmem_ida, GFP_KERNEL);
 898         if (rval < 0) {
 899                 kfree(nvmem);
 900                 return ERR_PTR(rval);
 901         }
 902
 903         nvmem->id = rval;
 904
 905         nvmem->dev.type = &nvmem_provider_type;
 906         nvmem->dev.bus = &nvmem_bus_type;
 907         nvmem->dev.parent = config->dev;
 908
 909         device_initialize(&nvmem->dev);
 910
 911         if (!config->ignore_wp)
 912                 nvmem->wp_gpio = gpiod_get_optional(config->dev, "wp",
 913                                                     GPIOD_OUT_HIGH);
 914         if (IS_ERR(nvmem->wp_gpio)) {
 915                 rval = PTR_ERR(nvmem->wp_gpio);
 916                 nvmem->wp_gpio = NULL;
 917                 goto err_put_device;
 918         }
 919
 920         kref_init(&nvmem->refcnt);
 921         INIT_LIST_HEAD(&nvmem->cells);
 922
 923         nvmem->owner = config->owner;
 924         if (!nvmem->owner && config->dev->driver)
 925                 nvmem->owner = config->dev->driver->owner;
 926         nvmem->stride = config->stride ?: 1;
 927         nvmem->word_size = config->word_size ?: 1;
 928         nvmem->size = config->size;
 929         nvmem->root_only = config->root_only;
 930         nvmem->priv = config->priv;
 931         nvmem->type = config->type;
 932         nvmem->reg_read = config->reg_read;
 933         nvmem->reg_write = config->reg_write;
 934         nvmem->keepout = config->keepout;
 935         nvmem->nkeepout = config->nkeepout;
 936         if (config->of_node)
 937                 nvmem->dev.of_node = config->of_node;
 938         else
 939                 nvmem->dev.of_node = config->dev->of_node;
 940
 941         switch (config->id) {
 942         case NVMEM_DEVID_NONE:
 943                 rval = dev_set_name(&nvmem->dev, "%s", config->name);
 944                 break;
 945         case NVMEM_DEVID_AUTO:
 946                 rval = dev_set_name(&nvmem->dev, "%s%d", config->name, nvmem->id);
 947                 break;
 948         default:
 949                 rval = dev_set_name(&nvmem->dev, "%s%d",
 950                              config->name ? : "nvmem",
 951                              config->name ? config->id : nvmem->id);
 952                 break;
 953         }
 954
 955         if (rval)
 956                 goto err_put_device;
 957
 958         nvmem->read_only = device_property_present(config->dev, "read-only") ||
 959                            config->read_only || !nvmem->reg_write;
 960
 961 #ifdef CONFIG_NVMEM_SYSFS
 962         nvmem->dev.groups = nvmem_dev_groups;
 963 #endif
 964
 965         if (nvmem->nkeepout) {
 966                 rval = nvmem_validate_keepouts(nvmem);
 967                 if (rval)
 968                         goto err_put_device;
 969         }
 970
 971         if (config->compat) {
 972                 rval = nvmem_sysfs_setup_compat(nvmem, config);
 973                 if (rval)
 974                         goto err_put_device;
 975         }
 976
 977         /*
 978          * If the driver supplied a layout by config->layout, the module
 979          * pointer will be NULL and nvmem_layout_put() will be a noop.
 980          */
 981         nvmem->layout = config->layout ?: nvmem_layout_get(nvmem);
 982         if (IS_ERR(nvmem->layout)) {
 983                 rval = PTR_ERR(nvmem->layout);
 984                 nvmem->layout = NULL;
 985
 986                 if (rval == -EPROBE_DEFER)
 987                         goto err_teardown_compat;
 988         }
 989
 990         if (config->cells) {
 991                 rval = nvmem_add_cells(nvmem, config->cells, config->ncells);
 992                 if (rval)
 993                         goto err_remove_cells;
 994         }
 995
 996         rval = nvmem_add_cells_from_table(nvmem);
 997         if (rval)
 998                 goto err_remove_cells;
 999
1000         if (config->add_legacy_fixed_of_cells) {
1001                 rval = nvmem_add_cells_from_legacy_of(nvmem);
1002                 if (rval)
1003                         goto err_remove_cells;
1004         }
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         dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
1015
1016         rval = device_add(&nvmem->dev);
1017         if (rval)
1018                 goto err_remove_cells;
1019
1020         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem);
1021
1022         return nvmem;
1023
1024 err_remove_cells:
1025         nvmem_device_remove_all_cells(nvmem);
1026         nvmem_layout_put(nvmem->layout);
1027 err_teardown_compat:
1028         if (config->compat)
1029                 nvmem_sysfs_remove_compat(nvmem, config);
1030 err_put_device:
1031         put_device(&nvmem->dev);
1032
1033         return ERR_PTR(rval);
1034 }
1035 EXPORT_SYMBOL_GPL(nvmem_register);
1036
1037 static void nvmem_device_release(struct kref *kref)
1038 {
1039         struct nvmem_device *nvmem;
1040
1041         nvmem = container_of(kref, struct nvmem_device, refcnt);
1042
1043         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_REMOVE, nvmem);
1044
1045         if (nvmem->flags & FLAG_COMPAT)
1046                 device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
1047
1048         nvmem_device_remove_all_cells(nvmem);
1049         nvmem_layout_put(nvmem->layout);
1050         device_unregister(&nvmem->dev);
1051 }
1052
1053 /**
1054  * nvmem_unregister() - Unregister previously registered nvmem device
1055  *
1056  * @nvmem: Pointer to previously registered nvmem device.
1057  */
1058 void nvmem_unregister(struct nvmem_device *nvmem)
1059 {
1060         if (nvmem)
1061                 kref_put(&nvmem->refcnt, nvmem_device_release);
1062 }
1063 EXPORT_SYMBOL_GPL(nvmem_unregister);
1064
1065 static void devm_nvmem_unregister(void *nvmem)
1066 {
1067         nvmem_unregister(nvmem);
1068 }
1069
1070 /**
1071  * devm_nvmem_register() - Register a managed nvmem device for given
1072  * nvmem_config.
1073  * Also creates a binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
1074  *
1075  * @dev: Device that uses the nvmem device.
1076  * @config: nvmem device configuration with which nvmem device is created.
1077  *
1078  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
1079  * on success.
1080  */
1081 struct nvmem_device *devm_nvmem_register(struct device *dev,
1082                                          const struct nvmem_config *config)
1083 {
1084         struct nvmem_device *nvmem;
1085         int ret;
1086
1087         nvmem = nvmem_register(config);
1088         if (IS_ERR(nvmem))
1089                 return nvmem;
1090
1091         ret = devm_add_action_or_reset(dev, devm_nvmem_unregister, nvmem);
1092         if (ret)
1093                 return ERR_PTR(ret);
1094
1095         return nvmem;
1096 }
1097 EXPORT_SYMBOL_GPL(devm_nvmem_register);
1098
1099 static struct nvmem_device *__nvmem_device_get(void *data,
1100                         int (*match)(struct device *dev, const void *data))
1101 {
1102         struct nvmem_device *nvmem = NULL;
1103         struct device *dev;
1104
1105         mutex_lock(&nvmem_mutex);
1106         dev = bus_find_device(&nvmem_bus_type, NULL, data, match);
1107         if (dev)
1108                 nvmem = to_nvmem_device(dev);
1109         mutex_unlock(&nvmem_mutex);
1110         if (!nvmem)
1111                 return ERR_PTR(-EPROBE_DEFER);
1112
1113         if (!try_module_get(nvmem->owner)) {
1114                 dev_err(&nvmem->dev,
1115                         "could not increase module refcount for cell %s\n",
1116                         nvmem_dev_name(nvmem));
1117
1118                 put_device(&nvmem->dev);
1119                 return ERR_PTR(-EINVAL);
1120         }
1121
1122         kref_get(&nvmem->refcnt);
1123
1124         return nvmem;
1125 }
1126
1127 static void __nvmem_device_put(struct nvmem_device *nvmem)
1128 {
1129         put_device(&nvmem->dev);
1130         module_put(nvmem->owner);
1131         kref_put(&nvmem->refcnt, nvmem_device_release);
1132 }
1133
1134 #if IS_ENABLED(CONFIG_OF)
1135 /**
1136  * of_nvmem_device_get() - Get nvmem device from a given id
1137  *
1138  * @np: Device tree node that uses the nvmem device.
1139  * @id: nvmem name from nvmem-names property.
1140  *
1141  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1142  * on success.
1143  */
1144 struct nvmem_device *of_nvmem_device_get(struct device_node *np, const char *id)
1145 {
1146
1147         struct device_node *nvmem_np;
1148         struct nvmem_device *nvmem;
1149         int index = 0;
1150
1151         if (id)
1152                 index = of_property_match_string(np, "nvmem-names", id);
1153
1154         nvmem_np = of_parse_phandle(np, "nvmem", index);
1155         if (!nvmem_np)
1156                 return ERR_PTR(-ENOENT);
1157
1158         nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
1159         of_node_put(nvmem_np);
1160         return nvmem;
1161 }
1162 EXPORT_SYMBOL_GPL(of_nvmem_device_get);
1163 #endif
1164
1165 /**
1166  * nvmem_device_get() - Get nvmem device from a given id
1167  *
1168  * @dev: Device that uses the nvmem device.
1169  * @dev_name: name of the requested nvmem device.
1170  *
1171  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1172  * on success.
1173  */
1174 struct nvmem_device *nvmem_device_get(struct device *dev, const char *dev_name)
1175 {
1176         if (dev->of_node) { /* try dt first */
1177                 struct nvmem_device *nvmem;
1178
1179                 nvmem = of_nvmem_device_get(dev->of_node, dev_name);
1180
1181                 if (!IS_ERR(nvmem) || PTR_ERR(nvmem) == -EPROBE_DEFER)
1182                         return nvmem;
1183
1184         }
1185
1186         return __nvmem_device_get((void *)dev_name, device_match_name);
1187 }
1188 EXPORT_SYMBOL_GPL(nvmem_device_get);
1189
1190 /**
1191  * nvmem_device_find() - Find nvmem device with matching function
1192  *
1193  * @data: Data to pass to match function
1194  * @match: Callback function to check device
1195  *
1196  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1197  * on success.
1198  */
1199 struct nvmem_device *nvmem_device_find(void *data,
1200                         int (*match)(struct device *dev, const void *data))
1201 {
1202         return __nvmem_device_get(data, match);
1203 }
1204 EXPORT_SYMBOL_GPL(nvmem_device_find);
1205
1206 static int devm_nvmem_device_match(struct device *dev, void *res, void *data)
1207 {
1208         struct nvmem_device **nvmem = res;
1209
1210         if (WARN_ON(!nvmem || !*nvmem))
1211                 return 0;
1212
1213         return *nvmem == data;
1214 }
1215
1216 static void devm_nvmem_device_release(struct device *dev, void *res)
1217 {
1218         nvmem_device_put(*(struct nvmem_device **)res);
1219 }
1220
1221 /**
1222  * devm_nvmem_device_put() - put alredy got nvmem device
1223  *
1224  * @dev: Device that uses the nvmem device.
1225  * @nvmem: pointer to nvmem device allocated by devm_nvmem_cell_get(),
1226  * that needs to be released.
1227  */
1228 void devm_nvmem_device_put(struct device *dev, struct nvmem_device *nvmem)
1229 {
1230         int ret;
1231
1232         ret = devres_release(dev, devm_nvmem_device_release,
1233                              devm_nvmem_device_match, nvmem);
1234
1235         WARN_ON(ret);
1236 }
1237 EXPORT_SYMBOL_GPL(devm_nvmem_device_put);
1238
1239 /**
1240  * nvmem_device_put() - put alredy got nvmem device
1241  *
1242  * @nvmem: pointer to nvmem device that needs to be released.
1243  */
1244 void nvmem_device_put(struct nvmem_device *nvmem)
1245 {
1246         __nvmem_device_put(nvmem);
1247 }
1248 EXPORT_SYMBOL_GPL(nvmem_device_put);
1249
1250 /**
1251  * devm_nvmem_device_get() - Get nvmem cell of device form a given id
1252  *
1253  * @dev: Device that requests the nvmem device.
1254  * @id: name id for the requested nvmem device.
1255  *
1256  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_cell
1257  * on success.  The nvmem_cell will be freed by the automatically once the
1258  * device is freed.
1259  */
1260 struct nvmem_device *devm_nvmem_device_get(struct device *dev, const char *id)
1261 {
1262         struct nvmem_device **ptr, *nvmem;
1263
1264         ptr = devres_alloc(devm_nvmem_device_release, sizeof(*ptr), GFP_KERNEL);
1265         if (!ptr)
1266                 return ERR_PTR(-ENOMEM);
1267
1268         nvmem = nvmem_device_get(dev, id);
1269         if (!IS_ERR(nvmem)) {
1270                 *ptr = nvmem;
1271                 devres_add(dev, ptr);
1272         } else {
1273                 devres_free(ptr);
1274         }
1275
1276         return nvmem;
1277 }
1278 EXPORT_SYMBOL_GPL(devm_nvmem_device_get);
1279
1280 static struct nvmem_cell *nvmem_create_cell(struct nvmem_cell_entry *entry,
1281                                             const char *id, int index)
1282 {
1283         struct nvmem_cell *cell;
1284         const char *name = NULL;
1285
1286         cell = kzalloc(sizeof(*cell), GFP_KERNEL);
1287         if (!cell)
1288                 return ERR_PTR(-ENOMEM);
1289
1290         if (id) {
1291                 name = kstrdup_const(id, GFP_KERNEL);
1292                 if (!name) {
1293                         kfree(cell);
1294                         return ERR_PTR(-ENOMEM);
1295                 }
1296         }
1297
1298         cell->id = name;
1299         cell->entry = entry;
1300         cell->index = index;
1301
1302         return cell;
1303 }
1304
1305 static struct nvmem_cell *
1306 nvmem_cell_get_from_lookup(struct device *dev, const char *con_id)
1307 {
1308         struct nvmem_cell_entry *cell_entry;
1309         struct nvmem_cell *cell = ERR_PTR(-ENOENT);
1310         struct nvmem_cell_lookup *lookup;
1311         struct nvmem_device *nvmem;
1312         const char *dev_id;
1313
1314         if (!dev)
1315                 return ERR_PTR(-EINVAL);
1316
1317         dev_id = dev_name(dev);
1318
1319         mutex_lock(&nvmem_lookup_mutex);
1320
1321         list_for_each_entry(lookup, &nvmem_lookup_list, node) {
1322                 if ((strcmp(lookup->dev_id, dev_id) == 0) &&
1323                     (strcmp(lookup->con_id, con_id) == 0)) {
1324                         /* This is the right entry. */
1325                         nvmem = __nvmem_device_get((void *)lookup->nvmem_name,
1326                                                    device_match_name);
1327                         if (IS_ERR(nvmem)) {
1328                                 /* Provider may not be registered yet. */
1329                                 cell = ERR_CAST(nvmem);
1330                                 break;
1331                         }
1332
1333                         cell_entry = nvmem_find_cell_entry_by_name(nvmem,
1334                                                                    lookup->cell_name);
1335                         if (!cell_entry) {
1336                                 __nvmem_device_put(nvmem);
1337                                 cell = ERR_PTR(-ENOENT);
1338                         } else {
1339                                 cell = nvmem_create_cell(cell_entry, con_id, 0);
1340                                 if (IS_ERR(cell))
1341                                         __nvmem_device_put(nvmem);
1342                         }
1343                         break;
1344                 }
1345         }
1346
1347         mutex_unlock(&nvmem_lookup_mutex);
1348         return cell;
1349 }
1350
1351 #if IS_ENABLED(CONFIG_OF)
1352 static struct nvmem_cell_entry *
1353 nvmem_find_cell_entry_by_node(struct nvmem_device *nvmem, struct device_node *np)
1354 {
1355         struct nvmem_cell_entry *iter, *cell = NULL;
1356
1357         mutex_lock(&nvmem_mutex);
1358         list_for_each_entry(iter, &nvmem->cells, node) {
1359                 if (np == iter->np) {
1360                         cell = iter;
1361                         break;
1362                 }
1363         }
1364         mutex_unlock(&nvmem_mutex);
1365
1366         return cell;
1367 }
1368
1369 /**
1370  * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
1371  *
1372  * @np: Device tree node that uses the nvmem cell.
1373  * @id: nvmem cell name from nvmem-cell-names property, or NULL
1374  *      for the cell at index 0 (the lone cell with no accompanying
1375  *      nvmem-cell-names property).
1376  *
1377  * Return: Will be an ERR_PTR() on error or a valid pointer
1378  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1379  * nvmem_cell_put().
1380  */
1381 struct nvmem_cell *of_nvmem_cell_get(struct device_node *np, const char *id)
1382 {
1383         struct device_node *cell_np, *nvmem_np;
1384         struct nvmem_device *nvmem;
1385         struct nvmem_cell_entry *cell_entry;
1386         struct nvmem_cell *cell;
1387         struct of_phandle_args cell_spec;
1388         int index = 0;
1389         int cell_index = 0;
1390         int ret;
1391
1392         /* if cell name exists, find index to the name */
1393         if (id)
1394                 index = of_property_match_string(np, "nvmem-cell-names", id);
1395
1396         ret = of_parse_phandle_with_optional_args(np, "nvmem-cells",
1397                                                   "#nvmem-cell-cells",
1398                                                   index, &cell_spec);
1399         if (ret)
1400                 return ERR_PTR(-ENOENT);
1401
1402         if (cell_spec.args_count > 1)
1403                 return ERR_PTR(-EINVAL);
1404
1405         cell_np = cell_spec.np;
1406         if (cell_spec.args_count)
1407                 cell_index = cell_spec.args[0];
1408
1409         nvmem_np = of_get_parent(cell_np);
1410         if (!nvmem_np) {
1411                 of_node_put(cell_np);
1412                 return ERR_PTR(-EINVAL);
1413         }
1414
1415         /* nvmem layouts produce cells within the nvmem-layout container */
1416         if (of_node_name_eq(nvmem_np, "nvmem-layout")) {
1417                 nvmem_np = of_get_next_parent(nvmem_np);
1418                 if (!nvmem_np) {
1419                         of_node_put(cell_np);
1420                         return ERR_PTR(-EINVAL);
1421                 }
1422         }
1423
1424         nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
1425         of_node_put(nvmem_np);
1426         if (IS_ERR(nvmem)) {
1427                 of_node_put(cell_np);
1428                 return ERR_CAST(nvmem);
1429         }
1430
1431         cell_entry = nvmem_find_cell_entry_by_node(nvmem, cell_np);
1432         of_node_put(cell_np);
1433         if (!cell_entry) {
1434                 __nvmem_device_put(nvmem);
1435                 return ERR_PTR(-ENOENT);
1436         }
1437
1438         cell = nvmem_create_cell(cell_entry, id, cell_index);
1439         if (IS_ERR(cell))
1440                 __nvmem_device_put(nvmem);
1441
1442         return cell;
1443 }
1444 EXPORT_SYMBOL_GPL(of_nvmem_cell_get);
1445 #endif
1446
1447 /**
1448  * nvmem_cell_get() - Get nvmem cell of device form a given cell name
1449  *
1450  * @dev: Device that requests the nvmem cell.
1451  * @id: nvmem cell name to get (this corresponds with the name from the
1452  *      nvmem-cell-names property for DT systems and with the con_id from
1453  *      the lookup entry for non-DT systems).
1454  *
1455  * Return: Will be an ERR_PTR() on error or a valid pointer
1456  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1457  * nvmem_cell_put().
1458  */
1459 struct nvmem_cell *nvmem_cell_get(struct device *dev, const char *id)
1460 {
1461         struct nvmem_cell *cell;
1462
1463         if (dev->of_node) { /* try dt first */
1464                 cell = of_nvmem_cell_get(dev->of_node, id);
1465                 if (!IS_ERR(cell) || PTR_ERR(cell) == -EPROBE_DEFER)
1466                         return cell;
1467         }
1468
1469         /* NULL cell id only allowed for device tree; invalid otherwise */
1470         if (!id)
1471                 return ERR_PTR(-EINVAL);
1472
1473         return nvmem_cell_get_from_lookup(dev, id);
1474 }
1475 EXPORT_SYMBOL_GPL(nvmem_cell_get);
1476
1477 static void devm_nvmem_cell_release(struct device *dev, void *res)
1478 {
1479         nvmem_cell_put(*(struct nvmem_cell **)res);
1480 }
1481
1482 /**
1483  * devm_nvmem_cell_get() - Get nvmem cell of device form a given id
1484  *
1485  * @dev: Device that requests the nvmem cell.
1486  * @id: nvmem cell name id to get.
1487  *
1488  * Return: Will be an ERR_PTR() on error or a valid pointer
1489  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1490  * automatically once the device is freed.
1491  */
1492 struct nvmem_cell *devm_nvmem_cell_get(struct device *dev, const char *id)
1493 {
1494         struct nvmem_cell **ptr, *cell;
1495
1496         ptr = devres_alloc(devm_nvmem_cell_release, sizeof(*ptr), GFP_KERNEL);
1497         if (!ptr)
1498                 return ERR_PTR(-ENOMEM);
1499
1500         cell = nvmem_cell_get(dev, id);
1501         if (!IS_ERR(cell)) {
1502                 *ptr = cell;
1503                 devres_add(dev, ptr);
1504         } else {
1505                 devres_free(ptr);
1506         }
1507
1508         return cell;
1509 }
1510 EXPORT_SYMBOL_GPL(devm_nvmem_cell_get);
1511
1512 static int devm_nvmem_cell_match(struct device *dev, void *res, void *data)
1513 {
1514         struct nvmem_cell **c = res;
1515
1516         if (WARN_ON(!c || !*c))
1517                 return 0;
1518
1519         return *c == data;
1520 }
1521
1522 /**
1523  * devm_nvmem_cell_put() - Release previously allocated nvmem cell
1524  * from devm_nvmem_cell_get.
1525  *
1526  * @dev: Device that requests the nvmem cell.
1527  * @cell: Previously allocated nvmem cell by devm_nvmem_cell_get().
1528  */
1529 void devm_nvmem_cell_put(struct device *dev, struct nvmem_cell *cell)
1530 {
1531         int ret;
1532
1533         ret = devres_release(dev, devm_nvmem_cell_release,
1534                                 devm_nvmem_cell_match, cell);
1535
1536         WARN_ON(ret);
1537 }
1538 EXPORT_SYMBOL(devm_nvmem_cell_put);
1539
1540 /**
1541  * nvmem_cell_put() - Release previously allocated nvmem cell.
1542  *
1543  * @cell: Previously allocated nvmem cell by nvmem_cell_get().
1544  */
1545 void nvmem_cell_put(struct nvmem_cell *cell)
1546 {
1547         struct nvmem_device *nvmem = cell->entry->nvmem;
1548
1549         if (cell->id)
1550                 kfree_const(cell->id);
1551
1552         kfree(cell);
1553         __nvmem_device_put(nvmem);
1554 }
1555 EXPORT_SYMBOL_GPL(nvmem_cell_put);
1556
1557 static void nvmem_shift_read_buffer_in_place(struct nvmem_cell_entry *cell, void *buf)
1558 {
1559         u8 *p, *b;
1560         int i, extra, bit_offset = cell->bit_offset;
1561
1562         p = b = buf;
1563         if (bit_offset) {
1564                 /* First shift */
1565                 *b++ >>= bit_offset;
1566
1567                 /* setup rest of the bytes if any */
1568                 for (i = 1; i < cell->bytes; i++) {
1569                         /* Get bits from next byte and shift them towards msb */
1570                         *p |= *b << (BITS_PER_BYTE - bit_offset);
1571
1572                         p = b;
1573                         *b++ >>= bit_offset;
1574                 }
1575         } else {
1576                 /* point to the msb */
1577                 p += cell->bytes - 1;
1578         }
1579
1580         /* result fits in less bytes */
1581         extra = cell->bytes - DIV_ROUND_UP(cell->nbits, BITS_PER_BYTE);
1582         while (--extra >= 0)
1583                 *p-- = 0;
1584
1585         /* clear msb bits if any leftover in the last byte */
1586         if (cell->nbits % BITS_PER_BYTE)
1587                 *p &= GENMASK((cell->nbits % BITS_PER_BYTE) - 1, 0);
1588 }
1589
1590 static int __nvmem_cell_read(struct nvmem_device *nvmem,
1591                              struct nvmem_cell_entry *cell,
1592                              void *buf, size_t *len, const char *id, int index)
1593 {
1594         int rc;
1595
1596         rc = nvmem_reg_read(nvmem, cell->offset, buf, cell->raw_len);
1597
1598         if (rc)
1599                 return rc;
1600
1601         /* shift bits in-place */
1602         if (cell->bit_offset || cell->nbits)
1603                 nvmem_shift_read_buffer_in_place(cell, buf);
1604
1605         if (cell->read_post_process) {
1606                 rc = cell->read_post_process(cell->priv, id, index,
1607                                              cell->offset, buf, cell->raw_len);
1608                 if (rc)
1609                         return rc;
1610         }
1611
1612         if (len)
1613                 *len = cell->bytes;
1614
1615         return 0;
1616 }
1617
1618 /**
1619  * nvmem_cell_read() - Read a given nvmem cell
1620  *
1621  * @cell: nvmem cell to be read.
1622  * @len: pointer to length of cell which will be populated on successful read;
1623  *       can be NULL.
1624  *
1625  * Return: ERR_PTR() on error or a valid pointer to a buffer on success. The
1626  * buffer should be freed by the consumer with a kfree().
1627  */
1628 void *nvmem_cell_read(struct nvmem_cell *cell, size_t *len)
1629 {
1630         struct nvmem_cell_entry *entry = cell->entry;
1631         struct nvmem_device *nvmem = entry->nvmem;
1632         u8 *buf;
1633         int rc;
1634
1635         if (!nvmem)
1636                 return ERR_PTR(-EINVAL);
1637
1638         buf = kzalloc(max_t(size_t, entry->raw_len, entry->bytes), GFP_KERNEL);
1639         if (!buf)
1640                 return ERR_PTR(-ENOMEM);
1641
1642         rc = __nvmem_cell_read(nvmem, cell->entry, buf, len, cell->id, cell->index);
1643         if (rc) {
1644                 kfree(buf);
1645                 return ERR_PTR(rc);
1646         }
1647
1648         return buf;
1649 }
1650 EXPORT_SYMBOL_GPL(nvmem_cell_read);
1651
1652 static void *nvmem_cell_prepare_write_buffer(struct nvmem_cell_entry *cell,
1653                                              u8 *_buf, int len)
1654 {
1655         struct nvmem_device *nvmem = cell->nvmem;
1656         int i, rc, nbits, bit_offset = cell->bit_offset;
1657         u8 v, *p, *buf, *b, pbyte, pbits;
1658
1659         nbits = cell->nbits;
1660         buf = kzalloc(cell->bytes, GFP_KERNEL);
1661         if (!buf)
1662                 return ERR_PTR(-ENOMEM);
1663
1664         memcpy(buf, _buf, len);
1665         p = b = buf;
1666
1667         if (bit_offset) {
1668                 pbyte = *b;
1669                 *b <<= bit_offset;
1670
1671                 /* setup the first byte with lsb bits from nvmem */
1672                 rc = nvmem_reg_read(nvmem, cell->offset, &v, 1);
1673                 if (rc)
1674                         goto err;
1675                 *b++ |= GENMASK(bit_offset - 1, 0) & v;
1676
1677                 /* setup rest of the byte if any */
1678                 for (i = 1; i < cell->bytes; i++) {
1679                         /* Get last byte bits and shift them towards lsb */
1680                         pbits = pbyte >> (BITS_PER_BYTE - 1 - bit_offset);
1681                         pbyte = *b;
1682                         p = b;
1683                         *b <<= bit_offset;
1684                         *b++ |= pbits;
1685                 }
1686         }
1687
1688         /* if it's not end on byte boundary */
1689         if ((nbits + bit_offset) % BITS_PER_BYTE) {
1690                 /* setup the last byte with msb bits from nvmem */
1691                 rc = nvmem_reg_read(nvmem,
1692                                     cell->offset + cell->bytes - 1, &v, 1);
1693                 if (rc)
1694                         goto err;
1695                 *p |= GENMASK(7, (nbits + bit_offset) % BITS_PER_BYTE) & v;
1696
1697         }
1698
1699         return buf;
1700 err:
1701         kfree(buf);
1702         return ERR_PTR(rc);
1703 }
1704
1705 static int __nvmem_cell_entry_write(struct nvmem_cell_entry *cell, void *buf, size_t len)
1706 {
1707         struct nvmem_device *nvmem = cell->nvmem;
1708         int rc;
1709
1710         if (!nvmem || nvmem->read_only ||
1711             (cell->bit_offset == 0 && len != cell->bytes))
1712                 return -EINVAL;
1713
1714         /*
1715          * Any cells which have a read_post_process hook are read-only because
1716          * we cannot reverse the operation and it might affect other cells,
1717          * too.
1718          */
1719         if (cell->read_post_process)
1720                 return -EINVAL;
1721
1722         if (cell->bit_offset || cell->nbits) {
1723                 buf = nvmem_cell_prepare_write_buffer(cell, buf, len);
1724                 if (IS_ERR(buf))
1725                         return PTR_ERR(buf);
1726         }
1727
1728         rc = nvmem_reg_write(nvmem, cell->offset, buf, cell->bytes);
1729
1730         /* free the tmp buffer */
1731         if (cell->bit_offset || cell->nbits)
1732                 kfree(buf);
1733
1734         if (rc)
1735                 return rc;
1736
1737         return len;
1738 }
1739
1740 /**
1741  * nvmem_cell_write() - Write to a given nvmem cell
1742  *
1743  * @cell: nvmem cell to be written.
1744  * @buf: Buffer to be written.
1745  * @len: length of buffer to be written to nvmem cell.
1746  *
1747  * Return: length of bytes written or negative on failure.
1748  */
1749 int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len)
1750 {
1751         return __nvmem_cell_entry_write(cell->entry, buf, len);
1752 }
1753
1754 EXPORT_SYMBOL_GPL(nvmem_cell_write);
1755
1756 static int nvmem_cell_read_common(struct device *dev, const char *cell_id,
1757                                   void *val, size_t count)
1758 {
1759         struct nvmem_cell *cell;
1760         void *buf;
1761         size_t len;
1762
1763         cell = nvmem_cell_get(dev, cell_id);
1764         if (IS_ERR(cell))
1765                 return PTR_ERR(cell);
1766
1767         buf = nvmem_cell_read(cell, &len);
1768         if (IS_ERR(buf)) {
1769                 nvmem_cell_put(cell);
1770                 return PTR_ERR(buf);
1771         }
1772         if (len != count) {
1773                 kfree(buf);
1774                 nvmem_cell_put(cell);
1775                 return -EINVAL;
1776         }
1777         memcpy(val, buf, count);
1778         kfree(buf);
1779         nvmem_cell_put(cell);
1780
1781         return 0;
1782 }
1783
1784 /**
1785  * nvmem_cell_read_u8() - Read a cell value as a u8
1786  *
1787  * @dev: Device that requests the nvmem cell.
1788  * @cell_id: Name of nvmem cell to read.
1789  * @val: pointer to output value.
1790  *
1791  * Return: 0 on success or negative errno.
1792  */
1793 int nvmem_cell_read_u8(struct device *dev, const char *cell_id, u8 *val)
1794 {
1795         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1796 }
1797 EXPORT_SYMBOL_GPL(nvmem_cell_read_u8);
1798
1799 /**
1800  * nvmem_cell_read_u16() - Read a cell value as a u16
1801  *
1802  * @dev: Device that requests the nvmem cell.
1803  * @cell_id: Name of nvmem cell to read.
1804  * @val: pointer to output value.
1805  *
1806  * Return: 0 on success or negative errno.
1807  */
1808 int nvmem_cell_read_u16(struct device *dev, const char *cell_id, u16 *val)
1809 {
1810         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1811 }
1812 EXPORT_SYMBOL_GPL(nvmem_cell_read_u16);
1813
1814 /**
1815  * nvmem_cell_read_u32() - Read a cell value as a u32
1816  *
1817  * @dev: Device that requests the nvmem cell.
1818  * @cell_id: Name of nvmem cell to read.
1819  * @val: pointer to output value.
1820  *
1821  * Return: 0 on success or negative errno.
1822  */
1823 int nvmem_cell_read_u32(struct device *dev, const char *cell_id, u32 *val)
1824 {
1825         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1826 }
1827 EXPORT_SYMBOL_GPL(nvmem_cell_read_u32);
1828
1829 /**
1830  * nvmem_cell_read_u64() - Read a cell value as a u64
1831  *
1832  * @dev: Device that requests the nvmem cell.
1833  * @cell_id: Name of nvmem cell to read.
1834  * @val: pointer to output value.
1835  *
1836  * Return: 0 on success or negative errno.
1837  */
1838 int nvmem_cell_read_u64(struct device *dev, const char *cell_id, u64 *val)
1839 {
1840         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1841 }
1842 EXPORT_SYMBOL_GPL(nvmem_cell_read_u64);
1843
1844 static const void *nvmem_cell_read_variable_common(struct device *dev,
1845                                                    const char *cell_id,
1846                                                    size_t max_len, size_t *len)
1847 {
1848         struct nvmem_cell *cell;
1849         int nbits;
1850         void *buf;
1851
1852         cell = nvmem_cell_get(dev, cell_id);
1853         if (IS_ERR(cell))
1854                 return cell;
1855
1856         nbits = cell->entry->nbits;
1857         buf = nvmem_cell_read(cell, len);
1858         nvmem_cell_put(cell);
1859         if (IS_ERR(buf))
1860                 return buf;
1861
1862         /*
1863          * If nbits is set then nvmem_cell_read() can significantly exaggerate
1864          * the length of the real data. Throw away the extra junk.
1865          */
1866         if (nbits)
1867                 *len = DIV_ROUND_UP(nbits, 8);
1868
1869         if (*len > max_len) {
1870                 kfree(buf);
1871                 return ERR_PTR(-ERANGE);
1872         }
1873
1874         return buf;
1875 }
1876
1877 /**
1878  * nvmem_cell_read_variable_le_u32() - Read up to 32-bits of data as a little endian number.
1879  *
1880  * @dev: Device that requests the nvmem cell.
1881  * @cell_id: Name of nvmem cell to read.
1882  * @val: pointer to output value.
1883  *
1884  * Return: 0 on success or negative errno.
1885  */
1886 int nvmem_cell_read_variable_le_u32(struct device *dev, const char *cell_id,
1887                                     u32 *val)
1888 {
1889         size_t len;
1890         const u8 *buf;
1891         int i;
1892
1893         buf = nvmem_cell_read_variable_common(dev, cell_id, sizeof(*val), &len);
1894         if (IS_ERR(buf))
1895                 return PTR_ERR(buf);
1896
1897         /* Copy w/ implicit endian conversion */
1898         *val = 0;
1899         for (i = 0; i < len; i++)
1900                 *val |= buf[i] << (8 * i);
1901
1902         kfree(buf);
1903
1904         return 0;
1905 }
1906 EXPORT_SYMBOL_GPL(nvmem_cell_read_variable_le_u32);
1907
1908 /**
1909  * nvmem_cell_read_variable_le_u64() - Read up to 64-bits of data as a little endian number.
1910  *
1911  * @dev: Device that requests the nvmem cell.
1912  * @cell_id: Name of nvmem cell to read.
1913  * @val: pointer to output value.
1914  *
1915  * Return: 0 on success or negative errno.
1916  */
1917 int nvmem_cell_read_variable_le_u64(struct device *dev, const char *cell_id,
1918                                     u64 *val)
1919 {
1920         size_t len;
1921         const u8 *buf;
1922         int i;
1923
1924         buf = nvmem_cell_read_variable_common(dev, cell_id, sizeof(*val), &len);
1925         if (IS_ERR(buf))
1926                 return PTR_ERR(buf);
1927
1928         /* Copy w/ implicit endian conversion */
1929         *val = 0;
1930         for (i = 0; i < len; i++)
1931                 *val |= (uint64_t)buf[i] << (8 * i);
1932
1933         kfree(buf);
1934
1935         return 0;
1936 }
1937 EXPORT_SYMBOL_GPL(nvmem_cell_read_variable_le_u64);
1938
1939 /**
1940  * nvmem_device_cell_read() - Read a given nvmem device and cell
1941  *
1942  * @nvmem: nvmem device to read from.
1943  * @info: nvmem cell info to be read.
1944  * @buf: buffer pointer which will be populated on successful read.
1945  *
1946  * Return: length of successful bytes read on success and negative
1947  * error code on error.
1948  */
1949 ssize_t nvmem_device_cell_read(struct nvmem_device *nvmem,
1950                            struct nvmem_cell_info *info, void *buf)
1951 {
1952         struct nvmem_cell_entry cell;
1953         int rc;
1954         ssize_t len;
1955
1956         if (!nvmem)
1957                 return -EINVAL;
1958
1959         rc = nvmem_cell_info_to_nvmem_cell_entry_nodup(nvmem, info, &cell);
1960         if (rc)
1961                 return rc;
1962
1963         rc = __nvmem_cell_read(nvmem, &cell, buf, &len, NULL, 0);
1964         if (rc)
1965                 return rc;
1966
1967         return len;
1968 }
1969 EXPORT_SYMBOL_GPL(nvmem_device_cell_read);
1970
1971 /**
1972  * nvmem_device_cell_write() - Write cell to a given nvmem device
1973  *
1974  * @nvmem: nvmem device to be written to.
1975  * @info: nvmem cell info to be written.
1976  * @buf: buffer to be written to cell.
1977  *
1978  * Return: length of bytes written or negative error code on failure.
1979  */
1980 int nvmem_device_cell_write(struct nvmem_device *nvmem,
1981                             struct nvmem_cell_info *info, void *buf)
1982 {
1983         struct nvmem_cell_entry cell;
1984         int rc;
1985
1986         if (!nvmem)
1987                 return -EINVAL;
1988
1989         rc = nvmem_cell_info_to_nvmem_cell_entry_nodup(nvmem, info, &cell);
1990         if (rc)
1991                 return rc;
1992
1993         return __nvmem_cell_entry_write(&cell, buf, cell.bytes);
1994 }
1995 EXPORT_SYMBOL_GPL(nvmem_device_cell_write);
1996
1997 /**
1998  * nvmem_device_read() - Read from a given nvmem device
1999  *
2000  * @nvmem: nvmem device to read from.
2001  * @offset: offset in nvmem device.
2002  * @bytes: number of bytes to read.
2003  * @buf: buffer pointer which will be populated on successful read.
2004  *
2005  * Return: length of successful bytes read on success and negative
2006  * error code on error.
2007  */
2008 int nvmem_device_read(struct nvmem_device *nvmem,
2009                       unsigned int offset,
2010                       size_t bytes, void *buf)
2011 {
2012         int rc;
2013
2014         if (!nvmem)
2015                 return -EINVAL;
2016
2017         rc = nvmem_reg_read(nvmem, offset, buf, bytes);
2018
2019         if (rc)
2020                 return rc;
2021
2022         return bytes;
2023 }
2024 EXPORT_SYMBOL_GPL(nvmem_device_read);
2025
2026 /**
2027  * nvmem_device_write() - Write cell to a given nvmem device
2028  *
2029  * @nvmem: nvmem device to be written to.
2030  * @offset: offset in nvmem device.
2031  * @bytes: number of bytes to write.
2032  * @buf: buffer to be written.
2033  *
2034  * Return: length of bytes written or negative error code on failure.
2035  */
2036 int nvmem_device_write(struct nvmem_device *nvmem,
2037                        unsigned int offset,
2038                        size_t bytes, void *buf)
2039 {
2040         int rc;
2041
2042         if (!nvmem)
2043                 return -EINVAL;
2044
2045         rc = nvmem_reg_write(nvmem, offset, buf, bytes);
2046
2047         if (rc)
2048                 return rc;
2049
2050
2051         return bytes;
2052 }
2053 EXPORT_SYMBOL_GPL(nvmem_device_write);
2054
2055 /**
2056  * nvmem_add_cell_table() - register a table of cell info entries
2057  *
2058  * @table: table of cell info entries
2059  */
2060 void nvmem_add_cell_table(struct nvmem_cell_table *table)
2061 {
2062         mutex_lock(&nvmem_cell_mutex);
2063         list_add_tail(&table->node, &nvmem_cell_tables);
2064         mutex_unlock(&nvmem_cell_mutex);
2065 }
2066 EXPORT_SYMBOL_GPL(nvmem_add_cell_table);
2067
2068 /**
2069  * nvmem_del_cell_table() - remove a previously registered cell info table
2070  *
2071  * @table: table of cell info entries
2072  */
2073 void nvmem_del_cell_table(struct nvmem_cell_table *table)
2074 {
2075         mutex_lock(&nvmem_cell_mutex);
2076         list_del(&table->node);
2077         mutex_unlock(&nvmem_cell_mutex);
2078 }
2079 EXPORT_SYMBOL_GPL(nvmem_del_cell_table);
2080
2081 /**
2082  * nvmem_add_cell_lookups() - register a list of cell lookup entries
2083  *
2084  * @entries: array of cell lookup entries
2085  * @nentries: number of cell lookup entries in the array
2086  */
2087 void nvmem_add_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
2088 {
2089         int i;
2090
2091         mutex_lock(&nvmem_lookup_mutex);
2092         for (i = 0; i < nentries; i++)
2093                 list_add_tail(&entries[i].node, &nvmem_lookup_list);
2094         mutex_unlock(&nvmem_lookup_mutex);
2095 }
2096 EXPORT_SYMBOL_GPL(nvmem_add_cell_lookups);
2097
2098 /**
2099  * nvmem_del_cell_lookups() - remove a list of previously added cell lookup
2100  *                            entries
2101  *
2102  * @entries: array of cell lookup entries
2103  * @nentries: number of cell lookup entries in the array
2104  */
2105 void nvmem_del_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
2106 {
2107         int i;
2108
2109         mutex_lock(&nvmem_lookup_mutex);
2110         for (i = 0; i < nentries; i++)
2111                 list_del(&entries[i].node);
2112         mutex_unlock(&nvmem_lookup_mutex);
2113 }
2114 EXPORT_SYMBOL_GPL(nvmem_del_cell_lookups);
2115
2116 /**
2117  * nvmem_dev_name() - Get the name of a given nvmem device.
2118  *
2119  * @nvmem: nvmem device.
2120  *
2121  * Return: name of the nvmem device.
2122  */
2123 const char *nvmem_dev_name(struct nvmem_device *nvmem)
2124 {
2125         return dev_name(&nvmem->dev);
2126 }
2127 EXPORT_SYMBOL_GPL(nvmem_dev_name);
2128
2129 static int __init nvmem_init(void)
2130 {
2131         return bus_register(&nvmem_bus_type);
2132 }
2133
2134 static void __exit nvmem_exit(void)
2135 {
2136         bus_unregister(&nvmem_bus_type);
2137 }
2138
2139 subsys_initcall(nvmem_init);
2140 module_exit(nvmem_exit);
2141
2142 MODULE_AUTHOR("Srinivas Kandagatla <[email protected]");
2143 MODULE_AUTHOR("Maxime Ripard <[email protected]");
2144 MODULE_DESCRIPTION("nvmem Driver Core");