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 #include "internals.h"
  23
  24 #define to_nvmem_device(d) container_of(d, struct nvmem_device, dev)
  25
  26 #define FLAG_COMPAT             BIT(0)
  27 struct nvmem_cell_entry {
  28         const char              *name;
  29         int                     offset;
  30         size_t                  raw_len;
  31         int                     bytes;
  32         int                     bit_offset;
  33         int                     nbits;
  34         nvmem_cell_post_process_t read_post_process;
  35         void                    *priv;
  36         struct device_node      *np;
  37         struct nvmem_device     *nvmem;
  38         struct list_head        node;
  39 };
  40
  41 struct nvmem_cell {
  42         struct nvmem_cell_entry *entry;
  43         const char              *id;
  44         int                     index;
  45 };
  46
  47 static DEFINE_MUTEX(nvmem_mutex);
  48 static DEFINE_IDA(nvmem_ida);
  49
  50 static DEFINE_MUTEX(nvmem_cell_mutex);
  51 static LIST_HEAD(nvmem_cell_tables);
  52
  53 static DEFINE_MUTEX(nvmem_lookup_mutex);
  54 static LIST_HEAD(nvmem_lookup_list);
  55
  56 static BLOCKING_NOTIFIER_HEAD(nvmem_notifier);
  57
  58 static int __nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
  59                             void *val, size_t bytes)
  60 {
  61         if (nvmem->reg_read)
  62                 return nvmem->reg_read(nvmem->priv, offset, val, bytes);
  63
  64         return -EINVAL;
  65 }
  66
  67 static int __nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
  68                              void *val, size_t bytes)
  69 {
  70         int ret;
  71
  72         if (nvmem->reg_write) {
  73                 gpiod_set_value_cansleep(nvmem->wp_gpio, 0);
  74                 ret = nvmem->reg_write(nvmem->priv, offset, val, bytes);
  75                 gpiod_set_value_cansleep(nvmem->wp_gpio, 1);
  76                 return ret;
  77         }
  78
  79         return -EINVAL;
  80 }
  81
  82 static int nvmem_access_with_keepouts(struct nvmem_device *nvmem,
  83                                       unsigned int offset, void *val,
  84                                       size_t bytes, int write)
  85 {
  86
  87         unsigned int end = offset + bytes;
  88         unsigned int kend, ksize;
  89         const struct nvmem_keepout *keepout = nvmem->keepout;
  90         const struct nvmem_keepout *keepoutend = keepout + nvmem->nkeepout;
  91         int rc;
  92
  93         /*
  94          * Skip all keepouts before the range being accessed.
  95          * Keepouts are sorted.
  96          */
  97         while ((keepout < keepoutend) && (keepout->end <= offset))
  98                 keepout++;
  99
 100         while ((offset < end) && (keepout < keepoutend)) {
 101                 /* Access the valid portion before the keepout. */
 102                 if (offset < keepout->start) {
 103                         kend = min(end, keepout->start);
 104                         ksize = kend - offset;
 105                         if (write)
 106                                 rc = __nvmem_reg_write(nvmem, offset, val, ksize);
 107                         else
 108                                 rc = __nvmem_reg_read(nvmem, offset, val, ksize);
 109
 110                         if (rc)
 111                                 return rc;
 112
 113                         offset += ksize;
 114                         val += ksize;
 115                 }
 116
 117                 /*
 118                  * Now we're aligned to the start of this keepout zone. Go
 119                  * through it.
 120                  */
 121                 kend = min(end, keepout->end);
 122                 ksize = kend - offset;
 123                 if (!write)
 124                         memset(val, keepout->value, ksize);
 125
 126                 val += ksize;
 127                 offset += ksize;
 128                 keepout++;
 129         }
 130
 131         /*
 132          * If we ran out of keepouts but there's still stuff to do, send it
 133          * down directly
 134          */
 135         if (offset < end) {
 136                 ksize = end - offset;
 137                 if (write)
 138                         return __nvmem_reg_write(nvmem, offset, val, ksize);
 139                 else
 140                         return __nvmem_reg_read(nvmem, offset, val, ksize);
 141         }
 142
 143         return 0;
 144 }
 145
 146 static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
 147                           void *val, size_t bytes)
 148 {
 149         if (!nvmem->nkeepout)
 150                 return __nvmem_reg_read(nvmem, offset, val, bytes);
 151
 152         return nvmem_access_with_keepouts(nvmem, offset, val, bytes, false);
 153 }
 154
 155 static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
 156                            void *val, size_t bytes)
 157 {
 158         if (!nvmem->nkeepout)
 159                 return __nvmem_reg_write(nvmem, offset, val, bytes);
 160
 161         return nvmem_access_with_keepouts(nvmem, offset, val, bytes, true);
 162 }
 163
 164 #ifdef CONFIG_NVMEM_SYSFS
 165 static const char * const nvmem_type_str[] = {
 166         [NVMEM_TYPE_UNKNOWN] = "Unknown",
 167         [NVMEM_TYPE_EEPROM] = "EEPROM",
 168         [NVMEM_TYPE_OTP] = "OTP",
 169         [NVMEM_TYPE_BATTERY_BACKED] = "Battery backed",
 170         [NVMEM_TYPE_FRAM] = "FRAM",
 171 };
 172
 173 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 174 static struct lock_class_key eeprom_lock_key;
 175 #endif
 176
 177 static ssize_t type_show(struct device *dev,
 178                          struct device_attribute *attr, char *buf)
 179 {
 180         struct nvmem_device *nvmem = to_nvmem_device(dev);
 181
 182         return sprintf(buf, "%s\n", nvmem_type_str[nvmem->type]);
 183 }
 184
 185 static DEVICE_ATTR_RO(type);
 186
 187 static struct attribute *nvmem_attrs[] = {
 188         &dev_attr_type.attr,
 189         NULL,
 190 };
 191
 192 static ssize_t bin_attr_nvmem_read(struct file *filp, struct kobject *kobj,
 193                                    struct bin_attribute *attr, char *buf,
 194                                    loff_t pos, size_t count)
 195 {
 196         struct device *dev;
 197         struct nvmem_device *nvmem;
 198         int rc;
 199
 200         if (attr->private)
 201                 dev = attr->private;
 202         else
 203                 dev = kobj_to_dev(kobj);
 204         nvmem = to_nvmem_device(dev);
 205
 206         /* Stop the user from reading */
 207         if (pos >= nvmem->size)
 208                 return 0;
 209
 210         if (!IS_ALIGNED(pos, nvmem->stride))
 211                 return -EINVAL;
 212
 213         if (count < nvmem->word_size)
 214                 return -EINVAL;
 215
 216         if (pos + count > nvmem->size)
 217                 count = nvmem->size - pos;
 218
 219         count = round_down(count, nvmem->word_size);
 220
 221         if (!nvmem->reg_read)
 222                 return -EPERM;
 223
 224         rc = nvmem_reg_read(nvmem, pos, buf, count);
 225
 226         if (rc)
 227                 return rc;
 228
 229         return count;
 230 }
 231
 232 static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj,
 233                                     struct bin_attribute *attr, char *buf,
 234                                     loff_t pos, size_t count)
 235 {
 236         struct device *dev;
 237         struct nvmem_device *nvmem;
 238         int rc;
 239
 240         if (attr->private)
 241                 dev = attr->private;
 242         else
 243                 dev = kobj_to_dev(kobj);
 244         nvmem = to_nvmem_device(dev);
 245
 246         /* Stop the user from writing */
 247         if (pos >= nvmem->size)
 248                 return -EFBIG;
 249
 250         if (!IS_ALIGNED(pos, nvmem->stride))
 251                 return -EINVAL;
 252
 253         if (count < nvmem->word_size)
 254                 return -EINVAL;
 255
 256         if (pos + count > nvmem->size)
 257                 count = nvmem->size - pos;
 258
 259         count = round_down(count, nvmem->word_size);
 260
 261         if (!nvmem->reg_write)
 262                 return -EPERM;
 263
 264         rc = nvmem_reg_write(nvmem, pos, buf, count);
 265
 266         if (rc)
 267                 return rc;
 268
 269         return count;
 270 }
 271
 272 static umode_t nvmem_bin_attr_get_umode(struct nvmem_device *nvmem)
 273 {
 274         umode_t mode = 0400;
 275
 276         if (!nvmem->root_only)
 277                 mode |= 0044;
 278
 279         if (!nvmem->read_only)
 280                 mode |= 0200;
 281
 282         if (!nvmem->reg_write)
 283                 mode &= ~0200;
 284
 285         if (!nvmem->reg_read)
 286                 mode &= ~0444;
 287
 288         return mode;
 289 }
 290
 291 static umode_t nvmem_bin_attr_is_visible(struct kobject *kobj,
 292                                          struct bin_attribute *attr, int i)
 293 {
 294         struct device *dev = kobj_to_dev(kobj);
 295         struct nvmem_device *nvmem = to_nvmem_device(dev);
 296
 297         attr->size = nvmem->size;
 298
 299         return nvmem_bin_attr_get_umode(nvmem);
 300 }
 301
 302 static struct nvmem_cell *nvmem_create_cell(struct nvmem_cell_entry *entry,
 303                                             const char *id, int index);
 304
 305 static ssize_t nvmem_cell_attr_read(struct file *filp, struct kobject *kobj,
 306                                     struct bin_attribute *attr, char *buf,
 307                                     loff_t pos, size_t count)
 308 {
 309         struct nvmem_cell_entry *entry;
 310         struct nvmem_cell *cell = NULL;
 311         size_t cell_sz, read_len;
 312         void *content;
 313
 314         entry = attr->private;
 315         cell = nvmem_create_cell(entry, entry->name, 0);
 316         if (IS_ERR(cell))
 317                 return PTR_ERR(cell);
 318
 319         if (!cell)
 320                 return -EINVAL;
 321
 322         content = nvmem_cell_read(cell, &cell_sz);
 323         if (IS_ERR(content)) {
 324                 read_len = PTR_ERR(content);
 325                 goto destroy_cell;
 326         }
 327
 328         read_len = min_t(unsigned int, cell_sz - pos, count);
 329         memcpy(buf, content + pos, read_len);
 330         kfree(content);
 331
 332 destroy_cell:
 333         kfree_const(cell->id);
 334         kfree(cell);
 335
 336         return read_len;
 337 }
 338
 339 /* default read/write permissions */
 340 static struct bin_attribute bin_attr_rw_nvmem = {
 341         .attr   = {
 342                 .name   = "nvmem",
 343                 .mode   = 0644,
 344         },
 345         .read   = bin_attr_nvmem_read,
 346         .write  = bin_attr_nvmem_write,
 347 };
 348
 349 static struct bin_attribute *nvmem_bin_attributes[] = {
 350         &bin_attr_rw_nvmem,
 351         NULL,
 352 };
 353
 354 static const struct attribute_group nvmem_bin_group = {
 355         .bin_attrs      = nvmem_bin_attributes,
 356         .attrs          = nvmem_attrs,
 357         .is_bin_visible = nvmem_bin_attr_is_visible,
 358 };
 359
 360 /* Cell attributes will be dynamically allocated */
 361 static struct attribute_group nvmem_cells_group = {
 362         .name           = "cells",
 363 };
 364
 365 static const struct attribute_group *nvmem_dev_groups[] = {
 366         &nvmem_bin_group,
 367         NULL,
 368 };
 369
 370 static const struct attribute_group *nvmem_cells_groups[] = {
 371         &nvmem_cells_group,
 372         NULL,
 373 };
 374
 375 static struct bin_attribute bin_attr_nvmem_eeprom_compat = {
 376         .attr   = {
 377                 .name   = "eeprom",
 378         },
 379         .read   = bin_attr_nvmem_read,
 380         .write  = bin_attr_nvmem_write,
 381 };
 382
 383 /*
 384  * nvmem_setup_compat() - Create an additional binary entry in
 385  * drivers sys directory, to be backwards compatible with the older
 386  * drivers/misc/eeprom drivers.
 387  */
 388 static int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
 389                                     const struct nvmem_config *config)
 390 {
 391         int rval;
 392
 393         if (!config->compat)
 394                 return 0;
 395
 396         if (!config->base_dev)
 397                 return -EINVAL;
 398
 399         if (config->type == NVMEM_TYPE_FRAM)
 400                 bin_attr_nvmem_eeprom_compat.attr.name = "fram";
 401
 402         nvmem->eeprom = bin_attr_nvmem_eeprom_compat;
 403         nvmem->eeprom.attr.mode = nvmem_bin_attr_get_umode(nvmem);
 404         nvmem->eeprom.size = nvmem->size;
 405 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 406         nvmem->eeprom.attr.key = &eeprom_lock_key;
 407 #endif
 408         nvmem->eeprom.private = &nvmem->dev;
 409         nvmem->base_dev = config->base_dev;
 410
 411         rval = device_create_bin_file(nvmem->base_dev, &nvmem->eeprom);
 412         if (rval) {
 413                 dev_err(&nvmem->dev,
 414                         "Failed to create eeprom binary file %d\n", rval);
 415                 return rval;
 416         }
 417
 418         nvmem->flags |= FLAG_COMPAT;
 419
 420         return 0;
 421 }
 422
 423 static void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem,
 424                               const struct nvmem_config *config)
 425 {
 426         if (config->compat)
 427                 device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
 428 }
 429
 430 static int nvmem_populate_sysfs_cells(struct nvmem_device *nvmem)
 431 {
 432         struct bin_attribute **cells_attrs, *attrs;
 433         struct nvmem_cell_entry *entry;
 434         unsigned int ncells = 0, i = 0;
 435         int ret = 0;
 436
 437         mutex_lock(&nvmem_mutex);
 438
 439         if (list_empty(&nvmem->cells) || nvmem->sysfs_cells_populated) {
 440                 nvmem_cells_group.bin_attrs = NULL;
 441                 goto unlock_mutex;
 442         }
 443
 444         /* Allocate an array of attributes with a sentinel */
 445         ncells = list_count_nodes(&nvmem->cells);
 446         cells_attrs = devm_kcalloc(&nvmem->dev, ncells + 1,
 447                                    sizeof(struct bin_attribute *), GFP_KERNEL);
 448         if (!cells_attrs) {
 449                 ret = -ENOMEM;
 450                 goto unlock_mutex;
 451         }
 452
 453         attrs = devm_kcalloc(&nvmem->dev, ncells, sizeof(struct bin_attribute), GFP_KERNEL);
 454         if (!attrs) {
 455                 ret = -ENOMEM;
 456                 goto unlock_mutex;
 457         }
 458
 459         /* Initialize each attribute to take the name and size of the cell */
 460         list_for_each_entry(entry, &nvmem->cells, node) {
 461                 sysfs_bin_attr_init(&attrs[i]);
 462                 attrs[i].attr.name = devm_kasprintf(&nvmem->dev, GFP_KERNEL,
 463                                                     "%s@%x,%x", entry->name,
 464                                                     entry->offset,
 465                                                     entry->bit_offset);
 466                 attrs[i].attr.mode = 0444;
 467                 attrs[i].size = entry->bytes;
 468                 attrs[i].read = &nvmem_cell_attr_read;
 469                 attrs[i].private = entry;
 470                 if (!attrs[i].attr.name) {
 471                         ret = -ENOMEM;
 472                         goto unlock_mutex;
 473                 }
 474
 475                 cells_attrs[i] = &attrs[i];
 476                 i++;
 477         }
 478
 479         nvmem_cells_group.bin_attrs = cells_attrs;
 480
 481         ret = devm_device_add_groups(&nvmem->dev, nvmem_cells_groups);
 482         if (ret)
 483                 goto unlock_mutex;
 484
 485         nvmem->sysfs_cells_populated = true;
 486
 487 unlock_mutex:
 488         mutex_unlock(&nvmem_mutex);
 489
 490         return ret;
 491 }
 492
 493 #else /* CONFIG_NVMEM_SYSFS */
 494
 495 static int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
 496                                     const struct nvmem_config *config)
 497 {
 498         return -ENOSYS;
 499 }
 500 static void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem,
 501                                       const struct nvmem_config *config)
 502 {
 503 }
 504
 505 #endif /* CONFIG_NVMEM_SYSFS */
 506
 507 static void nvmem_release(struct device *dev)
 508 {
 509         struct nvmem_device *nvmem = to_nvmem_device(dev);
 510
 511         ida_free(&nvmem_ida, nvmem->id);
 512         gpiod_put(nvmem->wp_gpio);
 513         kfree(nvmem);
 514 }
 515
 516 static const struct device_type nvmem_provider_type = {
 517         .release        = nvmem_release,
 518 };
 519
 520 static struct bus_type nvmem_bus_type = {
 521         .name           = "nvmem",
 522 };
 523
 524 static void nvmem_cell_entry_drop(struct nvmem_cell_entry *cell)
 525 {
 526         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_REMOVE, cell);
 527         mutex_lock(&nvmem_mutex);
 528         list_del(&cell->node);
 529         mutex_unlock(&nvmem_mutex);
 530         of_node_put(cell->np);
 531         kfree_const(cell->name);
 532         kfree(cell);
 533 }
 534
 535 static void nvmem_device_remove_all_cells(const struct nvmem_device *nvmem)
 536 {
 537         struct nvmem_cell_entry *cell, *p;
 538
 539         list_for_each_entry_safe(cell, p, &nvmem->cells, node)
 540                 nvmem_cell_entry_drop(cell);
 541 }
 542
 543 static void nvmem_cell_entry_add(struct nvmem_cell_entry *cell)
 544 {
 545         mutex_lock(&nvmem_mutex);
 546         list_add_tail(&cell->node, &cell->nvmem->cells);
 547         mutex_unlock(&nvmem_mutex);
 548         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_ADD, cell);
 549 }
 550
 551 static int nvmem_cell_info_to_nvmem_cell_entry_nodup(struct nvmem_device *nvmem,
 552                                                      const struct nvmem_cell_info *info,
 553                                                      struct nvmem_cell_entry *cell)
 554 {
 555         cell->nvmem = nvmem;
 556         cell->offset = info->offset;
 557         cell->raw_len = info->raw_len ?: info->bytes;
 558         cell->bytes = info->bytes;
 559         cell->name = info->name;
 560         cell->read_post_process = info->read_post_process;
 561         cell->priv = info->priv;
 562
 563         cell->bit_offset = info->bit_offset;
 564         cell->nbits = info->nbits;
 565         cell->np = info->np;
 566
 567         if (cell->nbits)
 568                 cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
 569                                            BITS_PER_BYTE);
 570
 571         if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
 572                 dev_err(&nvmem->dev,
 573                         "cell %s unaligned to nvmem stride %d\n",
 574                         cell->name ?: "<unknown>", nvmem->stride);
 575                 return -EINVAL;
 576         }
 577
 578         return 0;
 579 }
 580
 581 static int nvmem_cell_info_to_nvmem_cell_entry(struct nvmem_device *nvmem,
 582                                                const struct nvmem_cell_info *info,
 583                                                struct nvmem_cell_entry *cell)
 584 {
 585         int err;
 586
 587         err = nvmem_cell_info_to_nvmem_cell_entry_nodup(nvmem, info, cell);
 588         if (err)
 589                 return err;
 590
 591         cell->name = kstrdup_const(info->name, GFP_KERNEL);
 592         if (!cell->name)
 593                 return -ENOMEM;
 594
 595         return 0;
 596 }
 597
 598 /**
 599  * nvmem_add_one_cell() - Add one cell information to an nvmem device
 600  *
 601  * @nvmem: nvmem device to add cells to.
 602  * @info: nvmem cell info to add to the device
 603  *
 604  * Return: 0 or negative error code on failure.
 605  */
 606 int nvmem_add_one_cell(struct nvmem_device *nvmem,
 607                        const struct nvmem_cell_info *info)
 608 {
 609         struct nvmem_cell_entry *cell;
 610         int rval;
 611
 612         cell = kzalloc(sizeof(*cell), GFP_KERNEL);
 613         if (!cell)
 614                 return -ENOMEM;
 615
 616         rval = nvmem_cell_info_to_nvmem_cell_entry(nvmem, info, cell);
 617         if (rval) {
 618                 kfree(cell);
 619                 return rval;
 620         }
 621
 622         nvmem_cell_entry_add(cell);
 623
 624         return 0;
 625 }
 626 EXPORT_SYMBOL_GPL(nvmem_add_one_cell);
 627
 628 /**
 629  * nvmem_add_cells() - Add cell information to an nvmem device
 630  *
 631  * @nvmem: nvmem device to add cells to.
 632  * @info: nvmem cell info to add to the device
 633  * @ncells: number of cells in info
 634  *
 635  * Return: 0 or negative error code on failure.
 636  */
 637 static int nvmem_add_cells(struct nvmem_device *nvmem,
 638                     const struct nvmem_cell_info *info,
 639                     int ncells)
 640 {
 641         int i, rval;
 642
 643         for (i = 0; i < ncells; i++) {
 644                 rval = nvmem_add_one_cell(nvmem, &info[i]);
 645                 if (rval)
 646                         return rval;
 647         }
 648
 649         return 0;
 650 }
 651
 652 /**
 653  * nvmem_register_notifier() - Register a notifier block for nvmem events.
 654  *
 655  * @nb: notifier block to be called on nvmem events.
 656  *
 657  * Return: 0 on success, negative error number on failure.
 658  */
 659 int nvmem_register_notifier(struct notifier_block *nb)
 660 {
 661         return blocking_notifier_chain_register(&nvmem_notifier, nb);
 662 }
 663 EXPORT_SYMBOL_GPL(nvmem_register_notifier);
 664
 665 /**
 666  * nvmem_unregister_notifier() - Unregister a notifier block for nvmem events.
 667  *
 668  * @nb: notifier block to be unregistered.
 669  *
 670  * Return: 0 on success, negative error number on failure.
 671  */
 672 int nvmem_unregister_notifier(struct notifier_block *nb)
 673 {
 674         return blocking_notifier_chain_unregister(&nvmem_notifier, nb);
 675 }
 676 EXPORT_SYMBOL_GPL(nvmem_unregister_notifier);
 677
 678 static int nvmem_add_cells_from_table(struct nvmem_device *nvmem)
 679 {
 680         const struct nvmem_cell_info *info;
 681         struct nvmem_cell_table *table;
 682         struct nvmem_cell_entry *cell;
 683         int rval = 0, i;
 684
 685         mutex_lock(&nvmem_cell_mutex);
 686         list_for_each_entry(table, &nvmem_cell_tables, node) {
 687                 if (strcmp(nvmem_dev_name(nvmem), table->nvmem_name) == 0) {
 688                         for (i = 0; i < table->ncells; i++) {
 689                                 info = &table->cells[i];
 690
 691                                 cell = kzalloc(sizeof(*cell), GFP_KERNEL);
 692                                 if (!cell) {
 693                                         rval = -ENOMEM;
 694                                         goto out;
 695                                 }
 696
 697                                 rval = nvmem_cell_info_to_nvmem_cell_entry(nvmem, info, cell);
 698                                 if (rval) {
 699                                         kfree(cell);
 700                                         goto out;
 701                                 }
 702
 703                                 nvmem_cell_entry_add(cell);
 704                         }
 705                 }
 706         }
 707
 708 out:
 709         mutex_unlock(&nvmem_cell_mutex);
 710         return rval;
 711 }
 712
 713 static struct nvmem_cell_entry *
 714 nvmem_find_cell_entry_by_name(struct nvmem_device *nvmem, const char *cell_id)
 715 {
 716         struct nvmem_cell_entry *iter, *cell = NULL;
 717
 718         mutex_lock(&nvmem_mutex);
 719         list_for_each_entry(iter, &nvmem->cells, node) {
 720                 if (strcmp(cell_id, iter->name) == 0) {
 721                         cell = iter;
 722                         break;
 723                 }
 724         }
 725         mutex_unlock(&nvmem_mutex);
 726
 727         return cell;
 728 }
 729
 730 static int nvmem_validate_keepouts(struct nvmem_device *nvmem)
 731 {
 732         unsigned int cur = 0;
 733         const struct nvmem_keepout *keepout = nvmem->keepout;
 734         const struct nvmem_keepout *keepoutend = keepout + nvmem->nkeepout;
 735
 736         while (keepout < keepoutend) {
 737                 /* Ensure keepouts are sorted and don't overlap. */
 738                 if (keepout->start < cur) {
 739                         dev_err(&nvmem->dev,
 740                                 "Keepout regions aren't sorted or overlap.\n");
 741
 742                         return -ERANGE;
 743                 }
 744
 745                 if (keepout->end < keepout->start) {
 746                         dev_err(&nvmem->dev,
 747                                 "Invalid keepout region.\n");
 748
 749                         return -EINVAL;
 750                 }
 751
 752                 /*
 753                  * Validate keepouts (and holes between) don't violate
 754                  * word_size constraints.
 755                  */
 756                 if ((keepout->end - keepout->start < nvmem->word_size) ||
 757                     ((keepout->start != cur) &&
 758                      (keepout->start - cur < nvmem->word_size))) {
 759
 760                         dev_err(&nvmem->dev,
 761                                 "Keepout regions violate word_size constraints.\n");
 762
 763                         return -ERANGE;
 764                 }
 765
 766                 /* Validate keepouts don't violate stride (alignment). */
 767                 if (!IS_ALIGNED(keepout->start, nvmem->stride) ||
 768                     !IS_ALIGNED(keepout->end, nvmem->stride)) {
 769
 770                         dev_err(&nvmem->dev,
 771                                 "Keepout regions violate stride.\n");
 772
 773                         return -EINVAL;
 774                 }
 775
 776                 cur = keepout->end;
 777                 keepout++;
 778         }
 779
 780         return 0;
 781 }
 782
 783 static int nvmem_add_cells_from_dt(struct nvmem_device *nvmem, struct device_node *np)
 784 {
 785         struct device *dev = &nvmem->dev;
 786         struct device_node *child;
 787         const __be32 *addr;
 788         int len, ret;
 789
 790         for_each_child_of_node(np, child) {
 791                 struct nvmem_cell_info info = {0};
 792
 793                 addr = of_get_property(child, "reg", &len);
 794                 if (!addr)
 795                         continue;
 796                 if (len < 2 * sizeof(u32)) {
 797                         dev_err(dev, "nvmem: invalid reg on %pOF\n", child);
 798                         of_node_put(child);
 799                         return -EINVAL;
 800                 }
 801
 802                 info.offset = be32_to_cpup(addr++);
 803                 info.bytes = be32_to_cpup(addr);
 804                 info.name = kasprintf(GFP_KERNEL, "%pOFn", child);
 805
 806                 addr = of_get_property(child, "bits", &len);
 807                 if (addr && len == (2 * sizeof(u32))) {
 808                         info.bit_offset = be32_to_cpup(addr++);
 809                         info.nbits = be32_to_cpup(addr);
 810                         if (info.bit_offset >= BITS_PER_BYTE || info.nbits < 1) {
 811                                 dev_err(dev, "nvmem: invalid bits on %pOF\n", child);
 812                                 of_node_put(child);
 813                                 return -EINVAL;
 814                         }
 815                 }
 816
 817                 info.np = of_node_get(child);
 818
 819                 if (nvmem->fixup_dt_cell_info)
 820                         nvmem->fixup_dt_cell_info(nvmem, &info);
 821
 822                 ret = nvmem_add_one_cell(nvmem, &info);
 823                 kfree(info.name);
 824                 if (ret) {
 825                         of_node_put(child);
 826                         return ret;
 827                 }
 828         }
 829
 830         return 0;
 831 }
 832
 833 static int nvmem_add_cells_from_legacy_of(struct nvmem_device *nvmem)
 834 {
 835         return nvmem_add_cells_from_dt(nvmem, nvmem->dev.of_node);
 836 }
 837
 838 static int nvmem_add_cells_from_fixed_layout(struct nvmem_device *nvmem)
 839 {
 840         struct device_node *layout_np;
 841         int err = 0;
 842
 843         layout_np = of_nvmem_layout_get_container(nvmem);
 844         if (!layout_np)
 845                 return 0;
 846
 847         if (of_device_is_compatible(layout_np, "fixed-layout"))
 848                 err = nvmem_add_cells_from_dt(nvmem, layout_np);
 849
 850         of_node_put(layout_np);
 851
 852         return err;
 853 }
 854
 855 int nvmem_layout_register(struct nvmem_layout *layout)
 856 {
 857         int ret;
 858
 859         if (!layout->add_cells)
 860                 return -EINVAL;
 861
 862         /* Populate the cells */
 863         ret = layout->add_cells(layout);
 864         if (ret)
 865                 return ret;
 866
 867 #ifdef CONFIG_NVMEM_SYSFS
 868         ret = nvmem_populate_sysfs_cells(layout->nvmem);
 869         if (ret) {
 870                 nvmem_device_remove_all_cells(layout->nvmem);
 871                 return ret;
 872         }
 873 #endif
 874
 875         return 0;
 876 }
 877 EXPORT_SYMBOL_GPL(nvmem_layout_register);
 878
 879 void nvmem_layout_unregister(struct nvmem_layout *layout)
 880 {
 881         /* Keep the API even with an empty stub in case we need it later */
 882 }
 883 EXPORT_SYMBOL_GPL(nvmem_layout_unregister);
 884
 885 /**
 886  * nvmem_register() - Register a nvmem device for given nvmem_config.
 887  * Also creates a binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
 888  *
 889  * @config: nvmem device configuration with which nvmem device is created.
 890  *
 891  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
 892  * on success.
 893  */
 894
 895 struct nvmem_device *nvmem_register(const struct nvmem_config *config)
 896 {
 897         struct nvmem_device *nvmem;
 898         int rval;
 899
 900         if (!config->dev)
 901                 return ERR_PTR(-EINVAL);
 902
 903         if (!config->reg_read && !config->reg_write)
 904                 return ERR_PTR(-EINVAL);
 905
 906         nvmem = kzalloc(sizeof(*nvmem), GFP_KERNEL);
 907         if (!nvmem)
 908                 return ERR_PTR(-ENOMEM);
 909
 910         rval = ida_alloc(&nvmem_ida, GFP_KERNEL);
 911         if (rval < 0) {
 912                 kfree(nvmem);
 913                 return ERR_PTR(rval);
 914         }
 915
 916         nvmem->id = rval;
 917
 918         nvmem->dev.type = &nvmem_provider_type;
 919         nvmem->dev.bus = &nvmem_bus_type;
 920         nvmem->dev.parent = config->dev;
 921
 922         device_initialize(&nvmem->dev);
 923
 924         if (!config->ignore_wp)
 925                 nvmem->wp_gpio = gpiod_get_optional(config->dev, "wp",
 926                                                     GPIOD_OUT_HIGH);
 927         if (IS_ERR(nvmem->wp_gpio)) {
 928                 rval = PTR_ERR(nvmem->wp_gpio);
 929                 nvmem->wp_gpio = NULL;
 930                 goto err_put_device;
 931         }
 932
 933         kref_init(&nvmem->refcnt);
 934         INIT_LIST_HEAD(&nvmem->cells);
 935         nvmem->fixup_dt_cell_info = config->fixup_dt_cell_info;
 936
 937         nvmem->owner = config->owner;
 938         if (!nvmem->owner && config->dev->driver)
 939                 nvmem->owner = config->dev->driver->owner;
 940         nvmem->stride = config->stride ?: 1;
 941         nvmem->word_size = config->word_size ?: 1;
 942         nvmem->size = config->size;
 943         nvmem->root_only = config->root_only;
 944         nvmem->priv = config->priv;
 945         nvmem->type = config->type;
 946         nvmem->reg_read = config->reg_read;
 947         nvmem->reg_write = config->reg_write;
 948         nvmem->keepout = config->keepout;
 949         nvmem->nkeepout = config->nkeepout;
 950         if (config->of_node)
 951                 nvmem->dev.of_node = config->of_node;
 952         else
 953                 nvmem->dev.of_node = config->dev->of_node;
 954
 955         switch (config->id) {
 956         case NVMEM_DEVID_NONE:
 957                 rval = dev_set_name(&nvmem->dev, "%s", config->name);
 958                 break;
 959         case NVMEM_DEVID_AUTO:
 960                 rval = dev_set_name(&nvmem->dev, "%s%d", config->name, nvmem->id);
 961                 break;
 962         default:
 963                 rval = dev_set_name(&nvmem->dev, "%s%d",
 964                              config->name ? : "nvmem",
 965                              config->name ? config->id : nvmem->id);
 966                 break;
 967         }
 968
 969         if (rval)
 970                 goto err_put_device;
 971
 972         nvmem->read_only = device_property_present(config->dev, "read-only") ||
 973                            config->read_only || !nvmem->reg_write;
 974
 975 #ifdef CONFIG_NVMEM_SYSFS
 976         nvmem->dev.groups = nvmem_dev_groups;
 977 #endif
 978
 979         if (nvmem->nkeepout) {
 980                 rval = nvmem_validate_keepouts(nvmem);
 981                 if (rval)
 982                         goto err_put_device;
 983         }
 984
 985         if (config->compat) {
 986                 rval = nvmem_sysfs_setup_compat(nvmem, config);
 987                 if (rval)
 988                         goto err_put_device;
 989         }
 990
 991         if (config->cells) {
 992                 rval = nvmem_add_cells(nvmem, config->cells, config->ncells);
 993                 if (rval)
 994                         goto err_remove_cells;
 995         }
 996
 997         rval = nvmem_add_cells_from_table(nvmem);
 998         if (rval)
 999                 goto err_remove_cells;
1000
1001         if (config->add_legacy_fixed_of_cells) {
1002                 rval = nvmem_add_cells_from_legacy_of(nvmem);
1003                 if (rval)
1004                         goto err_remove_cells;
1005         }
1006
1007         rval = nvmem_add_cells_from_fixed_layout(nvmem);
1008         if (rval)
1009                 goto err_remove_cells;
1010
1011         dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
1012
1013         rval = device_add(&nvmem->dev);
1014         if (rval)
1015                 goto err_remove_cells;
1016
1017         rval = nvmem_populate_layout(nvmem);
1018         if (rval)
1019                 goto err_remove_dev;
1020
1021 #ifdef CONFIG_NVMEM_SYSFS
1022         rval = nvmem_populate_sysfs_cells(nvmem);
1023         if (rval)
1024                 goto err_destroy_layout;
1025 #endif
1026
1027         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem);
1028
1029         return nvmem;
1030
1031 #ifdef CONFIG_NVMEM_SYSFS
1032 err_destroy_layout:
1033         nvmem_destroy_layout(nvmem);
1034 #endif
1035 err_remove_dev:
1036         device_del(&nvmem->dev);
1037 err_remove_cells:
1038         nvmem_device_remove_all_cells(nvmem);
1039         if (config->compat)
1040                 nvmem_sysfs_remove_compat(nvmem, config);
1041 err_put_device:
1042         put_device(&nvmem->dev);
1043
1044         return ERR_PTR(rval);
1045 }
1046 EXPORT_SYMBOL_GPL(nvmem_register);
1047
1048 static void nvmem_device_release(struct kref *kref)
1049 {
1050         struct nvmem_device *nvmem;
1051
1052         nvmem = container_of(kref, struct nvmem_device, refcnt);
1053
1054         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_REMOVE, nvmem);
1055
1056         if (nvmem->flags & FLAG_COMPAT)
1057                 device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
1058
1059         nvmem_device_remove_all_cells(nvmem);
1060         nvmem_destroy_layout(nvmem);
1061         device_unregister(&nvmem->dev);
1062 }
1063
1064 /**
1065  * nvmem_unregister() - Unregister previously registered nvmem device
1066  *
1067  * @nvmem: Pointer to previously registered nvmem device.
1068  */
1069 void nvmem_unregister(struct nvmem_device *nvmem)
1070 {
1071         if (nvmem)
1072                 kref_put(&nvmem->refcnt, nvmem_device_release);
1073 }
1074 EXPORT_SYMBOL_GPL(nvmem_unregister);
1075
1076 static void devm_nvmem_unregister(void *nvmem)
1077 {
1078         nvmem_unregister(nvmem);
1079 }
1080
1081 /**
1082  * devm_nvmem_register() - Register a managed nvmem device for given
1083  * nvmem_config.
1084  * Also creates a binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
1085  *
1086  * @dev: Device that uses the nvmem device.
1087  * @config: nvmem device configuration with which nvmem device is created.
1088  *
1089  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
1090  * on success.
1091  */
1092 struct nvmem_device *devm_nvmem_register(struct device *dev,
1093                                          const struct nvmem_config *config)
1094 {
1095         struct nvmem_device *nvmem;
1096         int ret;
1097
1098         nvmem = nvmem_register(config);
1099         if (IS_ERR(nvmem))
1100                 return nvmem;
1101
1102         ret = devm_add_action_or_reset(dev, devm_nvmem_unregister, nvmem);
1103         if (ret)
1104                 return ERR_PTR(ret);
1105
1106         return nvmem;
1107 }
1108 EXPORT_SYMBOL_GPL(devm_nvmem_register);
1109
1110 static struct nvmem_device *__nvmem_device_get(void *data,
1111                         int (*match)(struct device *dev, const void *data))
1112 {
1113         struct nvmem_device *nvmem = NULL;
1114         struct device *dev;
1115
1116         mutex_lock(&nvmem_mutex);
1117         dev = bus_find_device(&nvmem_bus_type, NULL, data, match);
1118         if (dev)
1119                 nvmem = to_nvmem_device(dev);
1120         mutex_unlock(&nvmem_mutex);
1121         if (!nvmem)
1122                 return ERR_PTR(-EPROBE_DEFER);
1123
1124         if (!try_module_get(nvmem->owner)) {
1125                 dev_err(&nvmem->dev,
1126                         "could not increase module refcount for cell %s\n",
1127                         nvmem_dev_name(nvmem));
1128
1129                 put_device(&nvmem->dev);
1130                 return ERR_PTR(-EINVAL);
1131         }
1132
1133         kref_get(&nvmem->refcnt);
1134
1135         return nvmem;
1136 }
1137
1138 static void __nvmem_device_put(struct nvmem_device *nvmem)
1139 {
1140         put_device(&nvmem->dev);
1141         module_put(nvmem->owner);
1142         kref_put(&nvmem->refcnt, nvmem_device_release);
1143 }
1144
1145 #if IS_ENABLED(CONFIG_OF)
1146 /**
1147  * of_nvmem_device_get() - Get nvmem device from a given id
1148  *
1149  * @np: Device tree node that uses the nvmem device.
1150  * @id: nvmem name from nvmem-names property.
1151  *
1152  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1153  * on success.
1154  */
1155 struct nvmem_device *of_nvmem_device_get(struct device_node *np, const char *id)
1156 {
1157
1158         struct device_node *nvmem_np;
1159         struct nvmem_device *nvmem;
1160         int index = 0;
1161
1162         if (id)
1163                 index = of_property_match_string(np, "nvmem-names", id);
1164
1165         nvmem_np = of_parse_phandle(np, "nvmem", index);
1166         if (!nvmem_np)
1167                 return ERR_PTR(-ENOENT);
1168
1169         nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
1170         of_node_put(nvmem_np);
1171         return nvmem;
1172 }
1173 EXPORT_SYMBOL_GPL(of_nvmem_device_get);
1174 #endif
1175
1176 /**
1177  * nvmem_device_get() - Get nvmem device from a given id
1178  *
1179  * @dev: Device that uses the nvmem device.
1180  * @dev_name: name of the requested nvmem device.
1181  *
1182  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1183  * on success.
1184  */
1185 struct nvmem_device *nvmem_device_get(struct device *dev, const char *dev_name)
1186 {
1187         if (dev->of_node) { /* try dt first */
1188                 struct nvmem_device *nvmem;
1189
1190                 nvmem = of_nvmem_device_get(dev->of_node, dev_name);
1191
1192                 if (!IS_ERR(nvmem) || PTR_ERR(nvmem) == -EPROBE_DEFER)
1193                         return nvmem;
1194
1195         }
1196
1197         return __nvmem_device_get((void *)dev_name, device_match_name);
1198 }
1199 EXPORT_SYMBOL_GPL(nvmem_device_get);
1200
1201 /**
1202  * nvmem_device_find() - Find nvmem device with matching function
1203  *
1204  * @data: Data to pass to match function
1205  * @match: Callback function to check device
1206  *
1207  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1208  * on success.
1209  */
1210 struct nvmem_device *nvmem_device_find(void *data,
1211                         int (*match)(struct device *dev, const void *data))
1212 {
1213         return __nvmem_device_get(data, match);
1214 }
1215 EXPORT_SYMBOL_GPL(nvmem_device_find);
1216
1217 static int devm_nvmem_device_match(struct device *dev, void *res, void *data)
1218 {
1219         struct nvmem_device **nvmem = res;
1220
1221         if (WARN_ON(!nvmem || !*nvmem))
1222                 return 0;
1223
1224         return *nvmem == data;
1225 }
1226
1227 static void devm_nvmem_device_release(struct device *dev, void *res)
1228 {
1229         nvmem_device_put(*(struct nvmem_device **)res);
1230 }
1231
1232 /**
1233  * devm_nvmem_device_put() - put alredy got nvmem device
1234  *
1235  * @dev: Device that uses the nvmem device.
1236  * @nvmem: pointer to nvmem device allocated by devm_nvmem_cell_get(),
1237  * that needs to be released.
1238  */
1239 void devm_nvmem_device_put(struct device *dev, struct nvmem_device *nvmem)
1240 {
1241         int ret;
1242
1243         ret = devres_release(dev, devm_nvmem_device_release,
1244                              devm_nvmem_device_match, nvmem);
1245
1246         WARN_ON(ret);
1247 }
1248 EXPORT_SYMBOL_GPL(devm_nvmem_device_put);
1249
1250 /**
1251  * nvmem_device_put() - put alredy got nvmem device
1252  *
1253  * @nvmem: pointer to nvmem device that needs to be released.
1254  */
1255 void nvmem_device_put(struct nvmem_device *nvmem)
1256 {
1257         __nvmem_device_put(nvmem);
1258 }
1259 EXPORT_SYMBOL_GPL(nvmem_device_put);
1260
1261 /**
1262  * devm_nvmem_device_get() - Get nvmem cell of device form a given id
1263  *
1264  * @dev: Device that requests the nvmem device.
1265  * @id: name id for the requested nvmem device.
1266  *
1267  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_cell
1268  * on success.  The nvmem_cell will be freed by the automatically once the
1269  * device is freed.
1270  */
1271 struct nvmem_device *devm_nvmem_device_get(struct device *dev, const char *id)
1272 {
1273         struct nvmem_device **ptr, *nvmem;
1274
1275         ptr = devres_alloc(devm_nvmem_device_release, sizeof(*ptr), GFP_KERNEL);
1276         if (!ptr)
1277                 return ERR_PTR(-ENOMEM);
1278
1279         nvmem = nvmem_device_get(dev, id);
1280         if (!IS_ERR(nvmem)) {
1281                 *ptr = nvmem;
1282                 devres_add(dev, ptr);
1283         } else {
1284                 devres_free(ptr);
1285         }
1286
1287         return nvmem;
1288 }
1289 EXPORT_SYMBOL_GPL(devm_nvmem_device_get);
1290
1291 static struct nvmem_cell *nvmem_create_cell(struct nvmem_cell_entry *entry,
1292                                             const char *id, int index)
1293 {
1294         struct nvmem_cell *cell;
1295         const char *name = NULL;
1296
1297         cell = kzalloc(sizeof(*cell), GFP_KERNEL);
1298         if (!cell)
1299                 return ERR_PTR(-ENOMEM);
1300
1301         if (id) {
1302                 name = kstrdup_const(id, GFP_KERNEL);
1303                 if (!name) {
1304                         kfree(cell);
1305                         return ERR_PTR(-ENOMEM);
1306                 }
1307         }
1308
1309         cell->id = name;
1310         cell->entry = entry;
1311         cell->index = index;
1312
1313         return cell;
1314 }
1315
1316 static struct nvmem_cell *
1317 nvmem_cell_get_from_lookup(struct device *dev, const char *con_id)
1318 {
1319         struct nvmem_cell_entry *cell_entry;
1320         struct nvmem_cell *cell = ERR_PTR(-ENOENT);
1321         struct nvmem_cell_lookup *lookup;
1322         struct nvmem_device *nvmem;
1323         const char *dev_id;
1324
1325         if (!dev)
1326                 return ERR_PTR(-EINVAL);
1327
1328         dev_id = dev_name(dev);
1329
1330         mutex_lock(&nvmem_lookup_mutex);
1331
1332         list_for_each_entry(lookup, &nvmem_lookup_list, node) {
1333                 if ((strcmp(lookup->dev_id, dev_id) == 0) &&
1334                     (strcmp(lookup->con_id, con_id) == 0)) {
1335                         /* This is the right entry. */
1336                         nvmem = __nvmem_device_get((void *)lookup->nvmem_name,
1337                                                    device_match_name);
1338                         if (IS_ERR(nvmem)) {
1339                                 /* Provider may not be registered yet. */
1340                                 cell = ERR_CAST(nvmem);
1341                                 break;
1342                         }
1343
1344                         cell_entry = nvmem_find_cell_entry_by_name(nvmem,
1345                                                                    lookup->cell_name);
1346                         if (!cell_entry) {
1347                                 __nvmem_device_put(nvmem);
1348                                 cell = ERR_PTR(-ENOENT);
1349                         } else {
1350                                 cell = nvmem_create_cell(cell_entry, con_id, 0);
1351                                 if (IS_ERR(cell))
1352                                         __nvmem_device_put(nvmem);
1353                         }
1354                         break;
1355                 }
1356         }
1357
1358         mutex_unlock(&nvmem_lookup_mutex);
1359         return cell;
1360 }
1361
1362 static void nvmem_layout_module_put(struct nvmem_device *nvmem)
1363 {
1364         if (nvmem->layout && nvmem->layout->dev.driver)
1365                 module_put(nvmem->layout->dev.driver->owner);
1366 }
1367
1368 #if IS_ENABLED(CONFIG_OF)
1369 static struct nvmem_cell_entry *
1370 nvmem_find_cell_entry_by_node(struct nvmem_device *nvmem, struct device_node *np)
1371 {
1372         struct nvmem_cell_entry *iter, *cell = NULL;
1373
1374         mutex_lock(&nvmem_mutex);
1375         list_for_each_entry(iter, &nvmem->cells, node) {
1376                 if (np == iter->np) {
1377                         cell = iter;
1378                         break;
1379                 }
1380         }
1381         mutex_unlock(&nvmem_mutex);
1382
1383         return cell;
1384 }
1385
1386 static int nvmem_layout_module_get_optional(struct nvmem_device *nvmem)
1387 {
1388         if (!nvmem->layout)
1389                 return 0;
1390
1391         if (!nvmem->layout->dev.driver ||
1392             !try_module_get(nvmem->layout->dev.driver->owner))
1393                 return -EPROBE_DEFER;
1394
1395         return 0;
1396 }
1397
1398 /**
1399  * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
1400  *
1401  * @np: Device tree node that uses the nvmem cell.
1402  * @id: nvmem cell name from nvmem-cell-names property, or NULL
1403  *      for the cell at index 0 (the lone cell with no accompanying
1404  *      nvmem-cell-names property).
1405  *
1406  * Return: Will be an ERR_PTR() on error or a valid pointer
1407  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1408  * nvmem_cell_put().
1409  */
1410 struct nvmem_cell *of_nvmem_cell_get(struct device_node *np, const char *id)
1411 {
1412         struct device_node *cell_np, *nvmem_np;
1413         struct nvmem_device *nvmem;
1414         struct nvmem_cell_entry *cell_entry;
1415         struct nvmem_cell *cell;
1416         struct of_phandle_args cell_spec;
1417         int index = 0;
1418         int cell_index = 0;
1419         int ret;
1420
1421         /* if cell name exists, find index to the name */
1422         if (id)
1423                 index = of_property_match_string(np, "nvmem-cell-names", id);
1424
1425         ret = of_parse_phandle_with_optional_args(np, "nvmem-cells",
1426                                                   "#nvmem-cell-cells",
1427                                                   index, &cell_spec);
1428         if (ret)
1429                 return ERR_PTR(-ENOENT);
1430
1431         if (cell_spec.args_count > 1)
1432                 return ERR_PTR(-EINVAL);
1433
1434         cell_np = cell_spec.np;
1435         if (cell_spec.args_count)
1436                 cell_index = cell_spec.args[0];
1437
1438         nvmem_np = of_get_parent(cell_np);
1439         if (!nvmem_np) {
1440                 of_node_put(cell_np);
1441                 return ERR_PTR(-EINVAL);
1442         }
1443
1444         /* nvmem layouts produce cells within the nvmem-layout container */
1445         if (of_node_name_eq(nvmem_np, "nvmem-layout")) {
1446                 nvmem_np = of_get_next_parent(nvmem_np);
1447                 if (!nvmem_np) {
1448                         of_node_put(cell_np);
1449                         return ERR_PTR(-EINVAL);
1450                 }
1451         }
1452
1453         nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
1454         of_node_put(nvmem_np);
1455         if (IS_ERR(nvmem)) {
1456                 of_node_put(cell_np);
1457                 return ERR_CAST(nvmem);
1458         }
1459
1460         ret = nvmem_layout_module_get_optional(nvmem);
1461         if (ret) {
1462                 of_node_put(cell_np);
1463                 __nvmem_device_put(nvmem);
1464                 return ERR_PTR(ret);
1465         }
1466
1467         cell_entry = nvmem_find_cell_entry_by_node(nvmem, cell_np);
1468         of_node_put(cell_np);
1469         if (!cell_entry) {
1470                 __nvmem_device_put(nvmem);
1471                 nvmem_layout_module_put(nvmem);
1472                 if (nvmem->layout)
1473                         return ERR_PTR(-EPROBE_DEFER);
1474                 else
1475                         return ERR_PTR(-ENOENT);
1476         }
1477
1478         cell = nvmem_create_cell(cell_entry, id, cell_index);
1479         if (IS_ERR(cell)) {
1480                 __nvmem_device_put(nvmem);
1481                 nvmem_layout_module_put(nvmem);
1482         }
1483
1484         return cell;
1485 }
1486 EXPORT_SYMBOL_GPL(of_nvmem_cell_get);
1487 #endif
1488
1489 /**
1490  * nvmem_cell_get() - Get nvmem cell of device form a given cell name
1491  *
1492  * @dev: Device that requests the nvmem cell.
1493  * @id: nvmem cell name to get (this corresponds with the name from the
1494  *      nvmem-cell-names property for DT systems and with the con_id from
1495  *      the lookup entry for non-DT systems).
1496  *
1497  * Return: Will be an ERR_PTR() on error or a valid pointer
1498  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1499  * nvmem_cell_put().
1500  */
1501 struct nvmem_cell *nvmem_cell_get(struct device *dev, const char *id)
1502 {
1503         struct nvmem_cell *cell;
1504
1505         if (dev->of_node) { /* try dt first */
1506                 cell = of_nvmem_cell_get(dev->of_node, id);
1507                 if (!IS_ERR(cell) || PTR_ERR(cell) == -EPROBE_DEFER)
1508                         return cell;
1509         }
1510
1511         /* NULL cell id only allowed for device tree; invalid otherwise */
1512         if (!id)
1513                 return ERR_PTR(-EINVAL);
1514
1515         return nvmem_cell_get_from_lookup(dev, id);
1516 }
1517 EXPORT_SYMBOL_GPL(nvmem_cell_get);
1518
1519 static void devm_nvmem_cell_release(struct device *dev, void *res)
1520 {
1521         nvmem_cell_put(*(struct nvmem_cell **)res);
1522 }
1523
1524 /**
1525  * devm_nvmem_cell_get() - Get nvmem cell of device form a given id
1526  *
1527  * @dev: Device that requests the nvmem cell.
1528  * @id: nvmem cell name id to get.
1529  *
1530  * Return: Will be an ERR_PTR() on error or a valid pointer
1531  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1532  * automatically once the device is freed.
1533  */
1534 struct nvmem_cell *devm_nvmem_cell_get(struct device *dev, const char *id)
1535 {
1536         struct nvmem_cell **ptr, *cell;
1537
1538         ptr = devres_alloc(devm_nvmem_cell_release, sizeof(*ptr), GFP_KERNEL);
1539         if (!ptr)
1540                 return ERR_PTR(-ENOMEM);
1541
1542         cell = nvmem_cell_get(dev, id);
1543         if (!IS_ERR(cell)) {
1544                 *ptr = cell;
1545                 devres_add(dev, ptr);
1546         } else {
1547                 devres_free(ptr);
1548         }
1549
1550         return cell;
1551 }
1552 EXPORT_SYMBOL_GPL(devm_nvmem_cell_get);
1553
1554 static int devm_nvmem_cell_match(struct device *dev, void *res, void *data)
1555 {
1556         struct nvmem_cell **c = res;
1557
1558         if (WARN_ON(!c || !*c))
1559                 return 0;
1560
1561         return *c == data;
1562 }
1563
1564 /**
1565  * devm_nvmem_cell_put() - Release previously allocated nvmem cell
1566  * from devm_nvmem_cell_get.
1567  *
1568  * @dev: Device that requests the nvmem cell.
1569  * @cell: Previously allocated nvmem cell by devm_nvmem_cell_get().
1570  */
1571 void devm_nvmem_cell_put(struct device *dev, struct nvmem_cell *cell)
1572 {
1573         int ret;
1574
1575         ret = devres_release(dev, devm_nvmem_cell_release,
1576                                 devm_nvmem_cell_match, cell);
1577
1578         WARN_ON(ret);
1579 }
1580 EXPORT_SYMBOL(devm_nvmem_cell_put);
1581
1582 /**
1583  * nvmem_cell_put() - Release previously allocated nvmem cell.
1584  *
1585  * @cell: Previously allocated nvmem cell by nvmem_cell_get().
1586  */
1587 void nvmem_cell_put(struct nvmem_cell *cell)
1588 {
1589         struct nvmem_device *nvmem = cell->entry->nvmem;
1590
1591         if (cell->id)
1592                 kfree_const(cell->id);
1593
1594         kfree(cell);
1595         __nvmem_device_put(nvmem);
1596         nvmem_layout_module_put(nvmem);
1597 }
1598 EXPORT_SYMBOL_GPL(nvmem_cell_put);
1599
1600 static void nvmem_shift_read_buffer_in_place(struct nvmem_cell_entry *cell, void *buf)
1601 {
1602         u8 *p, *b;
1603         int i, extra, bit_offset = cell->bit_offset;
1604
1605         p = b = buf;
1606         if (bit_offset) {
1607                 /* First shift */
1608                 *b++ >>= bit_offset;
1609
1610                 /* setup rest of the bytes if any */
1611                 for (i = 1; i < cell->bytes; i++) {
1612                         /* Get bits from next byte and shift them towards msb */
1613                         *p |= *b << (BITS_PER_BYTE - bit_offset);
1614
1615                         p = b;
1616                         *b++ >>= bit_offset;
1617                 }
1618         } else {
1619                 /* point to the msb */
1620                 p += cell->bytes - 1;
1621         }
1622
1623         /* result fits in less bytes */
1624         extra = cell->bytes - DIV_ROUND_UP(cell->nbits, BITS_PER_BYTE);
1625         while (--extra >= 0)
1626                 *p-- = 0;
1627
1628         /* clear msb bits if any leftover in the last byte */
1629         if (cell->nbits % BITS_PER_BYTE)
1630                 *p &= GENMASK((cell->nbits % BITS_PER_BYTE) - 1, 0);
1631 }
1632
1633 static int __nvmem_cell_read(struct nvmem_device *nvmem,
1634                              struct nvmem_cell_entry *cell,
1635                              void *buf, size_t *len, const char *id, int index)
1636 {
1637         int rc;
1638
1639         rc = nvmem_reg_read(nvmem, cell->offset, buf, cell->raw_len);
1640
1641         if (rc)
1642                 return rc;
1643
1644         /* shift bits in-place */
1645         if (cell->bit_offset || cell->nbits)
1646                 nvmem_shift_read_buffer_in_place(cell, buf);
1647
1648         if (cell->read_post_process) {
1649                 rc = cell->read_post_process(cell->priv, id, index,
1650                                              cell->offset, buf, cell->raw_len);
1651                 if (rc)
1652                         return rc;
1653         }
1654
1655         if (len)
1656                 *len = cell->bytes;
1657
1658         return 0;
1659 }
1660
1661 /**
1662  * nvmem_cell_read() - Read a given nvmem cell
1663  *
1664  * @cell: nvmem cell to be read.
1665  * @len: pointer to length of cell which will be populated on successful read;
1666  *       can be NULL.
1667  *
1668  * Return: ERR_PTR() on error or a valid pointer to a buffer on success. The
1669  * buffer should be freed by the consumer with a kfree().
1670  */
1671 void *nvmem_cell_read(struct nvmem_cell *cell, size_t *len)
1672 {
1673         struct nvmem_cell_entry *entry = cell->entry;
1674         struct nvmem_device *nvmem = entry->nvmem;
1675         u8 *buf;
1676         int rc;
1677
1678         if (!nvmem)
1679                 return ERR_PTR(-EINVAL);
1680
1681         buf = kzalloc(max_t(size_t, entry->raw_len, entry->bytes), GFP_KERNEL);
1682         if (!buf)
1683                 return ERR_PTR(-ENOMEM);
1684
1685         rc = __nvmem_cell_read(nvmem, cell->entry, buf, len, cell->id, cell->index);
1686         if (rc) {
1687                 kfree(buf);
1688                 return ERR_PTR(rc);
1689         }
1690
1691         return buf;
1692 }
1693 EXPORT_SYMBOL_GPL(nvmem_cell_read);
1694
1695 static void *nvmem_cell_prepare_write_buffer(struct nvmem_cell_entry *cell,
1696                                              u8 *_buf, int len)
1697 {
1698         struct nvmem_device *nvmem = cell->nvmem;
1699         int i, rc, nbits, bit_offset = cell->bit_offset;
1700         u8 v, *p, *buf, *b, pbyte, pbits;
1701
1702         nbits = cell->nbits;
1703         buf = kzalloc(cell->bytes, GFP_KERNEL);
1704         if (!buf)
1705                 return ERR_PTR(-ENOMEM);
1706
1707         memcpy(buf, _buf, len);
1708         p = b = buf;
1709
1710         if (bit_offset) {
1711                 pbyte = *b;
1712                 *b <<= bit_offset;
1713
1714                 /* setup the first byte with lsb bits from nvmem */
1715                 rc = nvmem_reg_read(nvmem, cell->offset, &v, 1);
1716                 if (rc)
1717                         goto err;
1718                 *b++ |= GENMASK(bit_offset - 1, 0) & v;
1719
1720                 /* setup rest of the byte if any */
1721                 for (i = 1; i < cell->bytes; i++) {
1722                         /* Get last byte bits and shift them towards lsb */
1723                         pbits = pbyte >> (BITS_PER_BYTE - 1 - bit_offset);
1724                         pbyte = *b;
1725                         p = b;
1726                         *b <<= bit_offset;
1727                         *b++ |= pbits;
1728                 }
1729         }
1730
1731         /* if it's not end on byte boundary */
1732         if ((nbits + bit_offset) % BITS_PER_BYTE) {
1733                 /* setup the last byte with msb bits from nvmem */
1734                 rc = nvmem_reg_read(nvmem,
1735                                     cell->offset + cell->bytes - 1, &v, 1);
1736                 if (rc)
1737                         goto err;
1738                 *p |= GENMASK(7, (nbits + bit_offset) % BITS_PER_BYTE) & v;
1739
1740         }
1741
1742         return buf;
1743 err:
1744         kfree(buf);
1745         return ERR_PTR(rc);
1746 }
1747
1748 static int __nvmem_cell_entry_write(struct nvmem_cell_entry *cell, void *buf, size_t len)
1749 {
1750         struct nvmem_device *nvmem = cell->nvmem;
1751         int rc;
1752
1753         if (!nvmem || nvmem->read_only ||
1754             (cell->bit_offset == 0 && len != cell->bytes))
1755                 return -EINVAL;
1756
1757         /*
1758          * Any cells which have a read_post_process hook are read-only because
1759          * we cannot reverse the operation and it might affect other cells,
1760          * too.
1761          */
1762         if (cell->read_post_process)
1763                 return -EINVAL;
1764
1765         if (cell->bit_offset || cell->nbits) {
1766                 buf = nvmem_cell_prepare_write_buffer(cell, buf, len);
1767                 if (IS_ERR(buf))
1768                         return PTR_ERR(buf);
1769         }
1770
1771         rc = nvmem_reg_write(nvmem, cell->offset, buf, cell->bytes);
1772
1773         /* free the tmp buffer */
1774         if (cell->bit_offset || cell->nbits)
1775                 kfree(buf);
1776
1777         if (rc)
1778                 return rc;
1779
1780         return len;
1781 }
1782
1783 /**
1784  * nvmem_cell_write() - Write to a given nvmem cell
1785  *
1786  * @cell: nvmem cell to be written.
1787  * @buf: Buffer to be written.
1788  * @len: length of buffer to be written to nvmem cell.
1789  *
1790  * Return: length of bytes written or negative on failure.
1791  */
1792 int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len)
1793 {
1794         return __nvmem_cell_entry_write(cell->entry, buf, len);
1795 }
1796
1797 EXPORT_SYMBOL_GPL(nvmem_cell_write);
1798
1799 static int nvmem_cell_read_common(struct device *dev, const char *cell_id,
1800                                   void *val, size_t count)
1801 {
1802         struct nvmem_cell *cell;
1803         void *buf;
1804         size_t len;
1805
1806         cell = nvmem_cell_get(dev, cell_id);
1807         if (IS_ERR(cell))
1808                 return PTR_ERR(cell);
1809
1810         buf = nvmem_cell_read(cell, &len);
1811         if (IS_ERR(buf)) {
1812                 nvmem_cell_put(cell);
1813                 return PTR_ERR(buf);
1814         }
1815         if (len != count) {
1816                 kfree(buf);
1817                 nvmem_cell_put(cell);
1818                 return -EINVAL;
1819         }
1820         memcpy(val, buf, count);
1821         kfree(buf);
1822         nvmem_cell_put(cell);
1823
1824         return 0;
1825 }
1826
1827 /**
1828  * nvmem_cell_read_u8() - Read a cell value as a u8
1829  *
1830  * @dev: Device that requests the nvmem cell.
1831  * @cell_id: Name of nvmem cell to read.
1832  * @val: pointer to output value.
1833  *
1834  * Return: 0 on success or negative errno.
1835  */
1836 int nvmem_cell_read_u8(struct device *dev, const char *cell_id, u8 *val)
1837 {
1838         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1839 }
1840 EXPORT_SYMBOL_GPL(nvmem_cell_read_u8);
1841
1842 /**
1843  * nvmem_cell_read_u16() - Read a cell value as a u16
1844  *
1845  * @dev: Device that requests the nvmem cell.
1846  * @cell_id: Name of nvmem cell to read.
1847  * @val: pointer to output value.
1848  *
1849  * Return: 0 on success or negative errno.
1850  */
1851 int nvmem_cell_read_u16(struct device *dev, const char *cell_id, u16 *val)
1852 {
1853         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1854 }
1855 EXPORT_SYMBOL_GPL(nvmem_cell_read_u16);
1856
1857 /**
1858  * nvmem_cell_read_u32() - Read a cell value as a u32
1859  *
1860  * @dev: Device that requests the nvmem cell.
1861  * @cell_id: Name of nvmem cell to read.
1862  * @val: pointer to output value.
1863  *
1864  * Return: 0 on success or negative errno.
1865  */
1866 int nvmem_cell_read_u32(struct device *dev, const char *cell_id, u32 *val)
1867 {
1868         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1869 }
1870 EXPORT_SYMBOL_GPL(nvmem_cell_read_u32);
1871
1872 /**
1873  * nvmem_cell_read_u64() - Read a cell value as a u64
1874  *
1875  * @dev: Device that requests the nvmem cell.
1876  * @cell_id: Name of nvmem cell to read.
1877  * @val: pointer to output value.
1878  *
1879  * Return: 0 on success or negative errno.
1880  */
1881 int nvmem_cell_read_u64(struct device *dev, const char *cell_id, u64 *val)
1882 {
1883         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1884 }
1885 EXPORT_SYMBOL_GPL(nvmem_cell_read_u64);
1886
1887 static const void *nvmem_cell_read_variable_common(struct device *dev,
1888                                                    const char *cell_id,
1889                                                    size_t max_len, size_t *len)
1890 {
1891         struct nvmem_cell *cell;
1892         int nbits;
1893         void *buf;
1894
1895         cell = nvmem_cell_get(dev, cell_id);
1896         if (IS_ERR(cell))
1897                 return cell;
1898
1899         nbits = cell->entry->nbits;
1900         buf = nvmem_cell_read(cell, len);
1901         nvmem_cell_put(cell);
1902         if (IS_ERR(buf))
1903                 return buf;
1904
1905         /*
1906          * If nbits is set then nvmem_cell_read() can significantly exaggerate
1907          * the length of the real data. Throw away the extra junk.
1908          */
1909         if (nbits)
1910                 *len = DIV_ROUND_UP(nbits, 8);
1911
1912         if (*len > max_len) {
1913                 kfree(buf);
1914                 return ERR_PTR(-ERANGE);
1915         }
1916
1917         return buf;
1918 }
1919
1920 /**
1921  * nvmem_cell_read_variable_le_u32() - Read up to 32-bits of data as a little endian number.
1922  *
1923  * @dev: Device that requests the nvmem cell.
1924  * @cell_id: Name of nvmem cell to read.
1925  * @val: pointer to output value.
1926  *
1927  * Return: 0 on success or negative errno.
1928  */
1929 int nvmem_cell_read_variable_le_u32(struct device *dev, const char *cell_id,
1930                                     u32 *val)
1931 {
1932         size_t len;
1933         const u8 *buf;
1934         int i;
1935
1936         buf = nvmem_cell_read_variable_common(dev, cell_id, sizeof(*val), &len);
1937         if (IS_ERR(buf))
1938                 return PTR_ERR(buf);
1939
1940         /* Copy w/ implicit endian conversion */
1941         *val = 0;
1942         for (i = 0; i < len; i++)
1943                 *val |= buf[i] << (8 * i);
1944
1945         kfree(buf);
1946
1947         return 0;
1948 }
1949 EXPORT_SYMBOL_GPL(nvmem_cell_read_variable_le_u32);
1950
1951 /**
1952  * nvmem_cell_read_variable_le_u64() - Read up to 64-bits of data as a little endian number.
1953  *
1954  * @dev: Device that requests the nvmem cell.
1955  * @cell_id: Name of nvmem cell to read.
1956  * @val: pointer to output value.
1957  *
1958  * Return: 0 on success or negative errno.
1959  */
1960 int nvmem_cell_read_variable_le_u64(struct device *dev, const char *cell_id,
1961                                     u64 *val)
1962 {
1963         size_t len;
1964         const u8 *buf;
1965         int i;
1966
1967         buf = nvmem_cell_read_variable_common(dev, cell_id, sizeof(*val), &len);
1968         if (IS_ERR(buf))
1969                 return PTR_ERR(buf);
1970
1971         /* Copy w/ implicit endian conversion */
1972         *val = 0;
1973         for (i = 0; i < len; i++)
1974                 *val |= (uint64_t)buf[i] << (8 * i);
1975
1976         kfree(buf);
1977
1978         return 0;
1979 }
1980 EXPORT_SYMBOL_GPL(nvmem_cell_read_variable_le_u64);
1981
1982 /**
1983  * nvmem_device_cell_read() - Read a given nvmem device and cell
1984  *
1985  * @nvmem: nvmem device to read from.
1986  * @info: nvmem cell info to be read.
1987  * @buf: buffer pointer which will be populated on successful read.
1988  *
1989  * Return: length of successful bytes read on success and negative
1990  * error code on error.
1991  */
1992 ssize_t nvmem_device_cell_read(struct nvmem_device *nvmem,
1993                            struct nvmem_cell_info *info, void *buf)
1994 {
1995         struct nvmem_cell_entry cell;
1996         int rc;
1997         ssize_t len;
1998
1999         if (!nvmem)
2000                 return -EINVAL;
2001
2002         rc = nvmem_cell_info_to_nvmem_cell_entry_nodup(nvmem, info, &cell);
2003         if (rc)
2004                 return rc;
2005
2006         rc = __nvmem_cell_read(nvmem, &cell, buf, &len, NULL, 0);
2007         if (rc)
2008                 return rc;
2009
2010         return len;
2011 }
2012 EXPORT_SYMBOL_GPL(nvmem_device_cell_read);
2013
2014 /**
2015  * nvmem_device_cell_write() - Write cell to a given nvmem device
2016  *
2017  * @nvmem: nvmem device to be written to.
2018  * @info: nvmem cell info to be written.
2019  * @buf: buffer to be written to cell.
2020  *
2021  * Return: length of bytes written or negative error code on failure.
2022  */
2023 int nvmem_device_cell_write(struct nvmem_device *nvmem,
2024                             struct nvmem_cell_info *info, void *buf)
2025 {
2026         struct nvmem_cell_entry cell;
2027         int rc;
2028
2029         if (!nvmem)
2030                 return -EINVAL;
2031
2032         rc = nvmem_cell_info_to_nvmem_cell_entry_nodup(nvmem, info, &cell);
2033         if (rc)
2034                 return rc;
2035
2036         return __nvmem_cell_entry_write(&cell, buf, cell.bytes);
2037 }
2038 EXPORT_SYMBOL_GPL(nvmem_device_cell_write);
2039
2040 /**
2041  * nvmem_device_read() - Read from a given nvmem device
2042  *
2043  * @nvmem: nvmem device to read from.
2044  * @offset: offset in nvmem device.
2045  * @bytes: number of bytes to read.
2046  * @buf: buffer pointer which will be populated on successful read.
2047  *
2048  * Return: length of successful bytes read on success and negative
2049  * error code on error.
2050  */
2051 int nvmem_device_read(struct nvmem_device *nvmem,
2052                       unsigned int offset,
2053                       size_t bytes, void *buf)
2054 {
2055         int rc;
2056
2057         if (!nvmem)
2058                 return -EINVAL;
2059
2060         rc = nvmem_reg_read(nvmem, offset, buf, bytes);
2061
2062         if (rc)
2063                 return rc;
2064
2065         return bytes;
2066 }
2067 EXPORT_SYMBOL_GPL(nvmem_device_read);
2068
2069 /**
2070  * nvmem_device_write() - Write cell to a given nvmem device
2071  *
2072  * @nvmem: nvmem device to be written to.
2073  * @offset: offset in nvmem device.
2074  * @bytes: number of bytes to write.
2075  * @buf: buffer to be written.
2076  *
2077  * Return: length of bytes written or negative error code on failure.
2078  */
2079 int nvmem_device_write(struct nvmem_device *nvmem,
2080                        unsigned int offset,
2081                        size_t bytes, void *buf)
2082 {
2083         int rc;
2084
2085         if (!nvmem)
2086                 return -EINVAL;
2087
2088         rc = nvmem_reg_write(nvmem, offset, buf, bytes);
2089
2090         if (rc)
2091                 return rc;
2092
2093
2094         return bytes;
2095 }
2096 EXPORT_SYMBOL_GPL(nvmem_device_write);
2097
2098 /**
2099  * nvmem_add_cell_table() - register a table of cell info entries
2100  *
2101  * @table: table of cell info entries
2102  */
2103 void nvmem_add_cell_table(struct nvmem_cell_table *table)
2104 {
2105         mutex_lock(&nvmem_cell_mutex);
2106         list_add_tail(&table->node, &nvmem_cell_tables);
2107         mutex_unlock(&nvmem_cell_mutex);
2108 }
2109 EXPORT_SYMBOL_GPL(nvmem_add_cell_table);
2110
2111 /**
2112  * nvmem_del_cell_table() - remove a previously registered cell info table
2113  *
2114  * @table: table of cell info entries
2115  */
2116 void nvmem_del_cell_table(struct nvmem_cell_table *table)
2117 {
2118         mutex_lock(&nvmem_cell_mutex);
2119         list_del(&table->node);
2120         mutex_unlock(&nvmem_cell_mutex);
2121 }
2122 EXPORT_SYMBOL_GPL(nvmem_del_cell_table);
2123
2124 /**
2125  * nvmem_add_cell_lookups() - register a list of cell lookup entries
2126  *
2127  * @entries: array of cell lookup entries
2128  * @nentries: number of cell lookup entries in the array
2129  */
2130 void nvmem_add_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
2131 {
2132         int i;
2133
2134         mutex_lock(&nvmem_lookup_mutex);
2135         for (i = 0; i < nentries; i++)
2136                 list_add_tail(&entries[i].node, &nvmem_lookup_list);
2137         mutex_unlock(&nvmem_lookup_mutex);
2138 }
2139 EXPORT_SYMBOL_GPL(nvmem_add_cell_lookups);
2140
2141 /**
2142  * nvmem_del_cell_lookups() - remove a list of previously added cell lookup
2143  *                            entries
2144  *
2145  * @entries: array of cell lookup entries
2146  * @nentries: number of cell lookup entries in the array
2147  */
2148 void nvmem_del_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
2149 {
2150         int i;
2151
2152         mutex_lock(&nvmem_lookup_mutex);
2153         for (i = 0; i < nentries; i++)
2154                 list_del(&entries[i].node);
2155         mutex_unlock(&nvmem_lookup_mutex);
2156 }
2157 EXPORT_SYMBOL_GPL(nvmem_del_cell_lookups);
2158
2159 /**
2160  * nvmem_dev_name() - Get the name of a given nvmem device.
2161  *
2162  * @nvmem: nvmem device.
2163  *
2164  * Return: name of the nvmem device.
2165  */
2166 const char *nvmem_dev_name(struct nvmem_device *nvmem)
2167 {
2168         return dev_name(&nvmem->dev);
2169 }
2170 EXPORT_SYMBOL_GPL(nvmem_dev_name);
2171
2172 /**
2173  * nvmem_dev_size() - Get the size of a given nvmem device.
2174  *
2175  * @nvmem: nvmem device.
2176  *
2177  * Return: size of the nvmem device.
2178  */
2179 size_t nvmem_dev_size(struct nvmem_device *nvmem)
2180 {
2181         return nvmem->size;
2182 }
2183 EXPORT_SYMBOL_GPL(nvmem_dev_size);
2184
2185 static int __init nvmem_init(void)
2186 {
2187         int ret;
2188
2189         ret = bus_register(&nvmem_bus_type);
2190         if (ret)
2191                 return ret;
2192
2193         ret = nvmem_layout_bus_register();
2194         if (ret)
2195                 bus_unregister(&nvmem_bus_type);
2196
2197         return ret;
2198 }
2199
2200 static void __exit nvmem_exit(void)
2201 {
2202         nvmem_layout_bus_unregister();
2203         bus_unregister(&nvmem_bus_type);
2204 }
2205
2206 subsys_initcall(nvmem_init);
2207 module_exit(nvmem_exit);
2208
2209 MODULE_AUTHOR("Srinivas Kandagatla <srinivas.kandagatla@linaro.org");
2210 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com");
2211 MODULE_DESCRIPTION("nvmem Driver Core");