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                 }
 811
 812                 info.np = of_node_get(child);
 813
 814                 if (nvmem->fixup_dt_cell_info)
 815                         nvmem->fixup_dt_cell_info(nvmem, &info);
 816
 817                 ret = nvmem_add_one_cell(nvmem, &info);
 818                 kfree(info.name);
 819                 if (ret) {
 820                         of_node_put(child);
 821                         return ret;
 822                 }
 823         }
 824
 825         return 0;
 826 }
 827
 828 static int nvmem_add_cells_from_legacy_of(struct nvmem_device *nvmem)
 829 {
 830         return nvmem_add_cells_from_dt(nvmem, nvmem->dev.of_node);
 831 }
 832
 833 static int nvmem_add_cells_from_fixed_layout(struct nvmem_device *nvmem)
 834 {
 835         struct device_node *layout_np;
 836         int err = 0;
 837
 838         layout_np = of_nvmem_layout_get_container(nvmem);
 839         if (!layout_np)
 840                 return 0;
 841
 842         if (of_device_is_compatible(layout_np, "fixed-layout"))
 843                 err = nvmem_add_cells_from_dt(nvmem, layout_np);
 844
 845         of_node_put(layout_np);
 846
 847         return err;
 848 }
 849
 850 int nvmem_layout_register(struct nvmem_layout *layout)
 851 {
 852         int ret;
 853
 854         if (!layout->add_cells)
 855                 return -EINVAL;
 856
 857         /* Populate the cells */
 858         ret = layout->add_cells(layout);
 859         if (ret)
 860                 return ret;
 861
 862 #ifdef CONFIG_NVMEM_SYSFS
 863         ret = nvmem_populate_sysfs_cells(layout->nvmem);
 864         if (ret) {
 865                 nvmem_device_remove_all_cells(layout->nvmem);
 866                 return ret;
 867         }
 868 #endif
 869
 870         return 0;
 871 }
 872 EXPORT_SYMBOL_GPL(nvmem_layout_register);
 873
 874 void nvmem_layout_unregister(struct nvmem_layout *layout)
 875 {
 876         /* Keep the API even with an empty stub in case we need it later */
 877 }
 878 EXPORT_SYMBOL_GPL(nvmem_layout_unregister);
 879
 880 /**
 881  * nvmem_register() - Register a nvmem device for given nvmem_config.
 882  * Also creates a binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
 883  *
 884  * @config: nvmem device configuration with which nvmem device is created.
 885  *
 886  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
 887  * on success.
 888  */
 889
 890 struct nvmem_device *nvmem_register(const struct nvmem_config *config)
 891 {
 892         struct nvmem_device *nvmem;
 893         int rval;
 894
 895         if (!config->dev)
 896                 return ERR_PTR(-EINVAL);
 897
 898         if (!config->reg_read && !config->reg_write)
 899                 return ERR_PTR(-EINVAL);
 900
 901         nvmem = kzalloc(sizeof(*nvmem), GFP_KERNEL);
 902         if (!nvmem)
 903                 return ERR_PTR(-ENOMEM);
 904
 905         rval = ida_alloc(&nvmem_ida, GFP_KERNEL);
 906         if (rval < 0) {
 907                 kfree(nvmem);
 908                 return ERR_PTR(rval);
 909         }
 910
 911         nvmem->id = rval;
 912
 913         nvmem->dev.type = &nvmem_provider_type;
 914         nvmem->dev.bus = &nvmem_bus_type;
 915         nvmem->dev.parent = config->dev;
 916
 917         device_initialize(&nvmem->dev);
 918
 919         if (!config->ignore_wp)
 920                 nvmem->wp_gpio = gpiod_get_optional(config->dev, "wp",
 921                                                     GPIOD_OUT_HIGH);
 922         if (IS_ERR(nvmem->wp_gpio)) {
 923                 rval = PTR_ERR(nvmem->wp_gpio);
 924                 nvmem->wp_gpio = NULL;
 925                 goto err_put_device;
 926         }
 927
 928         kref_init(&nvmem->refcnt);
 929         INIT_LIST_HEAD(&nvmem->cells);
 930         nvmem->fixup_dt_cell_info = config->fixup_dt_cell_info;
 931
 932         nvmem->owner = config->owner;
 933         if (!nvmem->owner && config->dev->driver)
 934                 nvmem->owner = config->dev->driver->owner;
 935         nvmem->stride = config->stride ?: 1;
 936         nvmem->word_size = config->word_size ?: 1;
 937         nvmem->size = config->size;
 938         nvmem->root_only = config->root_only;
 939         nvmem->priv = config->priv;
 940         nvmem->type = config->type;
 941         nvmem->reg_read = config->reg_read;
 942         nvmem->reg_write = config->reg_write;
 943         nvmem->keepout = config->keepout;
 944         nvmem->nkeepout = config->nkeepout;
 945         if (config->of_node)
 946                 nvmem->dev.of_node = config->of_node;
 947         else
 948                 nvmem->dev.of_node = config->dev->of_node;
 949
 950         switch (config->id) {
 951         case NVMEM_DEVID_NONE:
 952                 rval = dev_set_name(&nvmem->dev, "%s", config->name);
 953                 break;
 954         case NVMEM_DEVID_AUTO:
 955                 rval = dev_set_name(&nvmem->dev, "%s%d", config->name, nvmem->id);
 956                 break;
 957         default:
 958                 rval = dev_set_name(&nvmem->dev, "%s%d",
 959                              config->name ? : "nvmem",
 960                              config->name ? config->id : nvmem->id);
 961                 break;
 962         }
 963
 964         if (rval)
 965                 goto err_put_device;
 966
 967         nvmem->read_only = device_property_present(config->dev, "read-only") ||
 968                            config->read_only || !nvmem->reg_write;
 969
 970 #ifdef CONFIG_NVMEM_SYSFS
 971         nvmem->dev.groups = nvmem_dev_groups;
 972 #endif
 973
 974         if (nvmem->nkeepout) {
 975                 rval = nvmem_validate_keepouts(nvmem);
 976                 if (rval)
 977                         goto err_put_device;
 978         }
 979
 980         if (config->compat) {
 981                 rval = nvmem_sysfs_setup_compat(nvmem, config);
 982                 if (rval)
 983                         goto err_put_device;
 984         }
 985
 986         if (config->cells) {
 987                 rval = nvmem_add_cells(nvmem, config->cells, config->ncells);
 988                 if (rval)
 989                         goto err_remove_cells;
 990         }
 991
 992         rval = nvmem_add_cells_from_table(nvmem);
 993         if (rval)
 994                 goto err_remove_cells;
 995
 996         if (config->add_legacy_fixed_of_cells) {
 997                 rval = nvmem_add_cells_from_legacy_of(nvmem);
 998                 if (rval)
 999                         goto err_remove_cells;
1000         }
1001
1002         rval = nvmem_add_cells_from_fixed_layout(nvmem);
1003         if (rval)
1004                 goto err_remove_cells;
1005
1006         dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
1007
1008         rval = device_add(&nvmem->dev);
1009         if (rval)
1010                 goto err_remove_cells;
1011
1012         rval = nvmem_populate_layout(nvmem);
1013         if (rval)
1014                 goto err_remove_dev;
1015
1016 #ifdef CONFIG_NVMEM_SYSFS
1017         rval = nvmem_populate_sysfs_cells(nvmem);
1018         if (rval)
1019                 goto err_destroy_layout;
1020 #endif
1021
1022         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem);
1023
1024         return nvmem;
1025
1026 #ifdef CONFIG_NVMEM_SYSFS
1027 err_destroy_layout:
1028         nvmem_destroy_layout(nvmem);
1029 #endif
1030 err_remove_dev:
1031         device_del(&nvmem->dev);
1032 err_remove_cells:
1033         nvmem_device_remove_all_cells(nvmem);
1034         if (config->compat)
1035                 nvmem_sysfs_remove_compat(nvmem, config);
1036 err_put_device:
1037         put_device(&nvmem->dev);
1038
1039         return ERR_PTR(rval);
1040 }
1041 EXPORT_SYMBOL_GPL(nvmem_register);
1042
1043 static void nvmem_device_release(struct kref *kref)
1044 {
1045         struct nvmem_device *nvmem;
1046
1047         nvmem = container_of(kref, struct nvmem_device, refcnt);
1048
1049         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_REMOVE, nvmem);
1050
1051         if (nvmem->flags & FLAG_COMPAT)
1052                 device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
1053
1054         nvmem_device_remove_all_cells(nvmem);
1055         nvmem_destroy_layout(nvmem);
1056         device_unregister(&nvmem->dev);
1057 }
1058
1059 /**
1060  * nvmem_unregister() - Unregister previously registered nvmem device
1061  *
1062  * @nvmem: Pointer to previously registered nvmem device.
1063  */
1064 void nvmem_unregister(struct nvmem_device *nvmem)
1065 {
1066         if (nvmem)
1067                 kref_put(&nvmem->refcnt, nvmem_device_release);
1068 }
1069 EXPORT_SYMBOL_GPL(nvmem_unregister);
1070
1071 static void devm_nvmem_unregister(void *nvmem)
1072 {
1073         nvmem_unregister(nvmem);
1074 }
1075
1076 /**
1077  * devm_nvmem_register() - Register a managed nvmem device for given
1078  * nvmem_config.
1079  * Also creates a binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
1080  *
1081  * @dev: Device that uses the nvmem device.
1082  * @config: nvmem device configuration with which nvmem device is created.
1083  *
1084  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
1085  * on success.
1086  */
1087 struct nvmem_device *devm_nvmem_register(struct device *dev,
1088                                          const struct nvmem_config *config)
1089 {
1090         struct nvmem_device *nvmem;
1091         int ret;
1092
1093         nvmem = nvmem_register(config);
1094         if (IS_ERR(nvmem))
1095                 return nvmem;
1096
1097         ret = devm_add_action_or_reset(dev, devm_nvmem_unregister, nvmem);
1098         if (ret)
1099                 return ERR_PTR(ret);
1100
1101         return nvmem;
1102 }
1103 EXPORT_SYMBOL_GPL(devm_nvmem_register);
1104
1105 static struct nvmem_device *__nvmem_device_get(void *data,
1106                         int (*match)(struct device *dev, const void *data))
1107 {
1108         struct nvmem_device *nvmem = NULL;
1109         struct device *dev;
1110
1111         mutex_lock(&nvmem_mutex);
1112         dev = bus_find_device(&nvmem_bus_type, NULL, data, match);
1113         if (dev)
1114                 nvmem = to_nvmem_device(dev);
1115         mutex_unlock(&nvmem_mutex);
1116         if (!nvmem)
1117                 return ERR_PTR(-EPROBE_DEFER);
1118
1119         if (!try_module_get(nvmem->owner)) {
1120                 dev_err(&nvmem->dev,
1121                         "could not increase module refcount for cell %s\n",
1122                         nvmem_dev_name(nvmem));
1123
1124                 put_device(&nvmem->dev);
1125                 return ERR_PTR(-EINVAL);
1126         }
1127
1128         kref_get(&nvmem->refcnt);
1129
1130         return nvmem;
1131 }
1132
1133 static void __nvmem_device_put(struct nvmem_device *nvmem)
1134 {
1135         put_device(&nvmem->dev);
1136         module_put(nvmem->owner);
1137         kref_put(&nvmem->refcnt, nvmem_device_release);
1138 }
1139
1140 #if IS_ENABLED(CONFIG_OF)
1141 /**
1142  * of_nvmem_device_get() - Get nvmem device from a given id
1143  *
1144  * @np: Device tree node that uses the nvmem device.
1145  * @id: nvmem name from nvmem-names property.
1146  *
1147  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1148  * on success.
1149  */
1150 struct nvmem_device *of_nvmem_device_get(struct device_node *np, const char *id)
1151 {
1152
1153         struct device_node *nvmem_np;
1154         struct nvmem_device *nvmem;
1155         int index = 0;
1156
1157         if (id)
1158                 index = of_property_match_string(np, "nvmem-names", id);
1159
1160         nvmem_np = of_parse_phandle(np, "nvmem", index);
1161         if (!nvmem_np)
1162                 return ERR_PTR(-ENOENT);
1163
1164         nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
1165         of_node_put(nvmem_np);
1166         return nvmem;
1167 }
1168 EXPORT_SYMBOL_GPL(of_nvmem_device_get);
1169 #endif
1170
1171 /**
1172  * nvmem_device_get() - Get nvmem device from a given id
1173  *
1174  * @dev: Device that uses the nvmem device.
1175  * @dev_name: name of the requested nvmem device.
1176  *
1177  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1178  * on success.
1179  */
1180 struct nvmem_device *nvmem_device_get(struct device *dev, const char *dev_name)
1181 {
1182         if (dev->of_node) { /* try dt first */
1183                 struct nvmem_device *nvmem;
1184
1185                 nvmem = of_nvmem_device_get(dev->of_node, dev_name);
1186
1187                 if (!IS_ERR(nvmem) || PTR_ERR(nvmem) == -EPROBE_DEFER)
1188                         return nvmem;
1189
1190         }
1191
1192         return __nvmem_device_get((void *)dev_name, device_match_name);
1193 }
1194 EXPORT_SYMBOL_GPL(nvmem_device_get);
1195
1196 /**
1197  * nvmem_device_find() - Find nvmem device with matching function
1198  *
1199  * @data: Data to pass to match function
1200  * @match: Callback function to check device
1201  *
1202  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1203  * on success.
1204  */
1205 struct nvmem_device *nvmem_device_find(void *data,
1206                         int (*match)(struct device *dev, const void *data))
1207 {
1208         return __nvmem_device_get(data, match);
1209 }
1210 EXPORT_SYMBOL_GPL(nvmem_device_find);
1211
1212 static int devm_nvmem_device_match(struct device *dev, void *res, void *data)
1213 {
1214         struct nvmem_device **nvmem = res;
1215
1216         if (WARN_ON(!nvmem || !*nvmem))
1217                 return 0;
1218
1219         return *nvmem == data;
1220 }
1221
1222 static void devm_nvmem_device_release(struct device *dev, void *res)
1223 {
1224         nvmem_device_put(*(struct nvmem_device **)res);
1225 }
1226
1227 /**
1228  * devm_nvmem_device_put() - put alredy got nvmem device
1229  *
1230  * @dev: Device that uses the nvmem device.
1231  * @nvmem: pointer to nvmem device allocated by devm_nvmem_cell_get(),
1232  * that needs to be released.
1233  */
1234 void devm_nvmem_device_put(struct device *dev, struct nvmem_device *nvmem)
1235 {
1236         int ret;
1237
1238         ret = devres_release(dev, devm_nvmem_device_release,
1239                              devm_nvmem_device_match, nvmem);
1240
1241         WARN_ON(ret);
1242 }
1243 EXPORT_SYMBOL_GPL(devm_nvmem_device_put);
1244
1245 /**
1246  * nvmem_device_put() - put alredy got nvmem device
1247  *
1248  * @nvmem: pointer to nvmem device that needs to be released.
1249  */
1250 void nvmem_device_put(struct nvmem_device *nvmem)
1251 {
1252         __nvmem_device_put(nvmem);
1253 }
1254 EXPORT_SYMBOL_GPL(nvmem_device_put);
1255
1256 /**
1257  * devm_nvmem_device_get() - Get nvmem cell of device form a given id
1258  *
1259  * @dev: Device that requests the nvmem device.
1260  * @id: name id for the requested nvmem device.
1261  *
1262  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_cell
1263  * on success.  The nvmem_cell will be freed by the automatically once the
1264  * device is freed.
1265  */
1266 struct nvmem_device *devm_nvmem_device_get(struct device *dev, const char *id)
1267 {
1268         struct nvmem_device **ptr, *nvmem;
1269
1270         ptr = devres_alloc(devm_nvmem_device_release, sizeof(*ptr), GFP_KERNEL);
1271         if (!ptr)
1272                 return ERR_PTR(-ENOMEM);
1273
1274         nvmem = nvmem_device_get(dev, id);
1275         if (!IS_ERR(nvmem)) {
1276                 *ptr = nvmem;
1277                 devres_add(dev, ptr);
1278         } else {
1279                 devres_free(ptr);
1280         }
1281
1282         return nvmem;
1283 }
1284 EXPORT_SYMBOL_GPL(devm_nvmem_device_get);
1285
1286 static struct nvmem_cell *nvmem_create_cell(struct nvmem_cell_entry *entry,
1287                                             const char *id, int index)
1288 {
1289         struct nvmem_cell *cell;
1290         const char *name = NULL;
1291
1292         cell = kzalloc(sizeof(*cell), GFP_KERNEL);
1293         if (!cell)
1294                 return ERR_PTR(-ENOMEM);
1295
1296         if (id) {
1297                 name = kstrdup_const(id, GFP_KERNEL);
1298                 if (!name) {
1299                         kfree(cell);
1300                         return ERR_PTR(-ENOMEM);
1301                 }
1302         }
1303
1304         cell->id = name;
1305         cell->entry = entry;
1306         cell->index = index;
1307
1308         return cell;
1309 }
1310
1311 static struct nvmem_cell *
1312 nvmem_cell_get_from_lookup(struct device *dev, const char *con_id)
1313 {
1314         struct nvmem_cell_entry *cell_entry;
1315         struct nvmem_cell *cell = ERR_PTR(-ENOENT);
1316         struct nvmem_cell_lookup *lookup;
1317         struct nvmem_device *nvmem;
1318         const char *dev_id;
1319
1320         if (!dev)
1321                 return ERR_PTR(-EINVAL);
1322
1323         dev_id = dev_name(dev);
1324
1325         mutex_lock(&nvmem_lookup_mutex);
1326
1327         list_for_each_entry(lookup, &nvmem_lookup_list, node) {
1328                 if ((strcmp(lookup->dev_id, dev_id) == 0) &&
1329                     (strcmp(lookup->con_id, con_id) == 0)) {
1330                         /* This is the right entry. */
1331                         nvmem = __nvmem_device_get((void *)lookup->nvmem_name,
1332                                                    device_match_name);
1333                         if (IS_ERR(nvmem)) {
1334                                 /* Provider may not be registered yet. */
1335                                 cell = ERR_CAST(nvmem);
1336                                 break;
1337                         }
1338
1339                         cell_entry = nvmem_find_cell_entry_by_name(nvmem,
1340                                                                    lookup->cell_name);
1341                         if (!cell_entry) {
1342                                 __nvmem_device_put(nvmem);
1343                                 cell = ERR_PTR(-ENOENT);
1344                         } else {
1345                                 cell = nvmem_create_cell(cell_entry, con_id, 0);
1346                                 if (IS_ERR(cell))
1347                                         __nvmem_device_put(nvmem);
1348                         }
1349                         break;
1350                 }
1351         }
1352
1353         mutex_unlock(&nvmem_lookup_mutex);
1354         return cell;
1355 }
1356
1357 static void nvmem_layout_module_put(struct nvmem_device *nvmem)
1358 {
1359         if (nvmem->layout && nvmem->layout->dev.driver)
1360                 module_put(nvmem->layout->dev.driver->owner);
1361 }
1362
1363 #if IS_ENABLED(CONFIG_OF)
1364 static struct nvmem_cell_entry *
1365 nvmem_find_cell_entry_by_node(struct nvmem_device *nvmem, struct device_node *np)
1366 {
1367         struct nvmem_cell_entry *iter, *cell = NULL;
1368
1369         mutex_lock(&nvmem_mutex);
1370         list_for_each_entry(iter, &nvmem->cells, node) {
1371                 if (np == iter->np) {
1372                         cell = iter;
1373                         break;
1374                 }
1375         }
1376         mutex_unlock(&nvmem_mutex);
1377
1378         return cell;
1379 }
1380
1381 static int nvmem_layout_module_get_optional(struct nvmem_device *nvmem)
1382 {
1383         if (!nvmem->layout)
1384                 return 0;
1385
1386         if (!nvmem->layout->dev.driver ||
1387             !try_module_get(nvmem->layout->dev.driver->owner))
1388                 return -EPROBE_DEFER;
1389
1390         return 0;
1391 }
1392
1393 /**
1394  * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
1395  *
1396  * @np: Device tree node that uses the nvmem cell.
1397  * @id: nvmem cell name from nvmem-cell-names property, or NULL
1398  *      for the cell at index 0 (the lone cell with no accompanying
1399  *      nvmem-cell-names property).
1400  *
1401  * Return: Will be an ERR_PTR() on error or a valid pointer
1402  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1403  * nvmem_cell_put().
1404  */
1405 struct nvmem_cell *of_nvmem_cell_get(struct device_node *np, const char *id)
1406 {
1407         struct device_node *cell_np, *nvmem_np;
1408         struct nvmem_device *nvmem;
1409         struct nvmem_cell_entry *cell_entry;
1410         struct nvmem_cell *cell;
1411         struct of_phandle_args cell_spec;
1412         int index = 0;
1413         int cell_index = 0;
1414         int ret;
1415
1416         /* if cell name exists, find index to the name */
1417         if (id)
1418                 index = of_property_match_string(np, "nvmem-cell-names", id);
1419
1420         ret = of_parse_phandle_with_optional_args(np, "nvmem-cells",
1421                                                   "#nvmem-cell-cells",
1422                                                   index, &cell_spec);
1423         if (ret)
1424                 return ERR_PTR(-ENOENT);
1425
1426         if (cell_spec.args_count > 1)
1427                 return ERR_PTR(-EINVAL);
1428
1429         cell_np = cell_spec.np;
1430         if (cell_spec.args_count)
1431                 cell_index = cell_spec.args[0];
1432
1433         nvmem_np = of_get_parent(cell_np);
1434         if (!nvmem_np) {
1435                 of_node_put(cell_np);
1436                 return ERR_PTR(-EINVAL);
1437         }
1438
1439         /* nvmem layouts produce cells within the nvmem-layout container */
1440         if (of_node_name_eq(nvmem_np, "nvmem-layout")) {
1441                 nvmem_np = of_get_next_parent(nvmem_np);
1442                 if (!nvmem_np) {
1443                         of_node_put(cell_np);
1444                         return ERR_PTR(-EINVAL);
1445                 }
1446         }
1447
1448         nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
1449         of_node_put(nvmem_np);
1450         if (IS_ERR(nvmem)) {
1451                 of_node_put(cell_np);
1452                 return ERR_CAST(nvmem);
1453         }
1454
1455         ret = nvmem_layout_module_get_optional(nvmem);
1456         if (ret) {
1457                 of_node_put(cell_np);
1458                 __nvmem_device_put(nvmem);
1459                 return ERR_PTR(ret);
1460         }
1461
1462         cell_entry = nvmem_find_cell_entry_by_node(nvmem, cell_np);
1463         of_node_put(cell_np);
1464         if (!cell_entry) {
1465                 __nvmem_device_put(nvmem);
1466                 nvmem_layout_module_put(nvmem);
1467                 if (nvmem->layout)
1468                         return ERR_PTR(-EPROBE_DEFER);
1469                 else
1470                         return ERR_PTR(-ENOENT);
1471         }
1472
1473         cell = nvmem_create_cell(cell_entry, id, cell_index);
1474         if (IS_ERR(cell)) {
1475                 __nvmem_device_put(nvmem);
1476                 nvmem_layout_module_put(nvmem);
1477         }
1478
1479         return cell;
1480 }
1481 EXPORT_SYMBOL_GPL(of_nvmem_cell_get);
1482 #endif
1483
1484 /**
1485  * nvmem_cell_get() - Get nvmem cell of device form a given cell name
1486  *
1487  * @dev: Device that requests the nvmem cell.
1488  * @id: nvmem cell name to get (this corresponds with the name from the
1489  *      nvmem-cell-names property for DT systems and with the con_id from
1490  *      the lookup entry for non-DT systems).
1491  *
1492  * Return: Will be an ERR_PTR() on error or a valid pointer
1493  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1494  * nvmem_cell_put().
1495  */
1496 struct nvmem_cell *nvmem_cell_get(struct device *dev, const char *id)
1497 {
1498         struct nvmem_cell *cell;
1499
1500         if (dev->of_node) { /* try dt first */
1501                 cell = of_nvmem_cell_get(dev->of_node, id);
1502                 if (!IS_ERR(cell) || PTR_ERR(cell) == -EPROBE_DEFER)
1503                         return cell;
1504         }
1505
1506         /* NULL cell id only allowed for device tree; invalid otherwise */
1507         if (!id)
1508                 return ERR_PTR(-EINVAL);
1509
1510         return nvmem_cell_get_from_lookup(dev, id);
1511 }
1512 EXPORT_SYMBOL_GPL(nvmem_cell_get);
1513
1514 static void devm_nvmem_cell_release(struct device *dev, void *res)
1515 {
1516         nvmem_cell_put(*(struct nvmem_cell **)res);
1517 }
1518
1519 /**
1520  * devm_nvmem_cell_get() - Get nvmem cell of device form a given id
1521  *
1522  * @dev: Device that requests the nvmem cell.
1523  * @id: nvmem cell name id to get.
1524  *
1525  * Return: Will be an ERR_PTR() on error or a valid pointer
1526  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1527  * automatically once the device is freed.
1528  */
1529 struct nvmem_cell *devm_nvmem_cell_get(struct device *dev, const char *id)
1530 {
1531         struct nvmem_cell **ptr, *cell;
1532
1533         ptr = devres_alloc(devm_nvmem_cell_release, sizeof(*ptr), GFP_KERNEL);
1534         if (!ptr)
1535                 return ERR_PTR(-ENOMEM);
1536
1537         cell = nvmem_cell_get(dev, id);
1538         if (!IS_ERR(cell)) {
1539                 *ptr = cell;
1540                 devres_add(dev, ptr);
1541         } else {
1542                 devres_free(ptr);
1543         }
1544
1545         return cell;
1546 }
1547 EXPORT_SYMBOL_GPL(devm_nvmem_cell_get);
1548
1549 static int devm_nvmem_cell_match(struct device *dev, void *res, void *data)
1550 {
1551         struct nvmem_cell **c = res;
1552
1553         if (WARN_ON(!c || !*c))
1554                 return 0;
1555
1556         return *c == data;
1557 }
1558
1559 /**
1560  * devm_nvmem_cell_put() - Release previously allocated nvmem cell
1561  * from devm_nvmem_cell_get.
1562  *
1563  * @dev: Device that requests the nvmem cell.
1564  * @cell: Previously allocated nvmem cell by devm_nvmem_cell_get().
1565  */
1566 void devm_nvmem_cell_put(struct device *dev, struct nvmem_cell *cell)
1567 {
1568         int ret;
1569
1570         ret = devres_release(dev, devm_nvmem_cell_release,
1571                                 devm_nvmem_cell_match, cell);
1572
1573         WARN_ON(ret);
1574 }
1575 EXPORT_SYMBOL(devm_nvmem_cell_put);
1576
1577 /**
1578  * nvmem_cell_put() - Release previously allocated nvmem cell.
1579  *
1580  * @cell: Previously allocated nvmem cell by nvmem_cell_get().
1581  */
1582 void nvmem_cell_put(struct nvmem_cell *cell)
1583 {
1584         struct nvmem_device *nvmem = cell->entry->nvmem;
1585
1586         if (cell->id)
1587                 kfree_const(cell->id);
1588
1589         kfree(cell);
1590         __nvmem_device_put(nvmem);
1591         nvmem_layout_module_put(nvmem);
1592 }
1593 EXPORT_SYMBOL_GPL(nvmem_cell_put);
1594
1595 static void nvmem_shift_read_buffer_in_place(struct nvmem_cell_entry *cell, void *buf)
1596 {
1597         u8 *p, *b;
1598         int i, extra, bit_offset = cell->bit_offset;
1599
1600         p = b = buf;
1601         if (bit_offset) {
1602                 /* First shift */
1603                 *b++ >>= bit_offset;
1604
1605                 /* setup rest of the bytes if any */
1606                 for (i = 1; i < cell->bytes; i++) {
1607                         /* Get bits from next byte and shift them towards msb */
1608                         *p |= *b << (BITS_PER_BYTE - bit_offset);
1609
1610                         p = b;
1611                         *b++ >>= bit_offset;
1612                 }
1613         } else {
1614                 /* point to the msb */
1615                 p += cell->bytes - 1;
1616         }
1617
1618         /* result fits in less bytes */
1619         extra = cell->bytes - DIV_ROUND_UP(cell->nbits, BITS_PER_BYTE);
1620         while (--extra >= 0)
1621                 *p-- = 0;
1622
1623         /* clear msb bits if any leftover in the last byte */
1624         if (cell->nbits % BITS_PER_BYTE)
1625                 *p &= GENMASK((cell->nbits % BITS_PER_BYTE) - 1, 0);
1626 }
1627
1628 static int __nvmem_cell_read(struct nvmem_device *nvmem,
1629                              struct nvmem_cell_entry *cell,
1630                              void *buf, size_t *len, const char *id, int index)
1631 {
1632         int rc;
1633
1634         rc = nvmem_reg_read(nvmem, cell->offset, buf, cell->raw_len);
1635
1636         if (rc)
1637                 return rc;
1638
1639         /* shift bits in-place */
1640         if (cell->bit_offset || cell->nbits)
1641                 nvmem_shift_read_buffer_in_place(cell, buf);
1642
1643         if (cell->read_post_process) {
1644                 rc = cell->read_post_process(cell->priv, id, index,
1645                                              cell->offset, buf, cell->raw_len);
1646                 if (rc)
1647                         return rc;
1648         }
1649
1650         if (len)
1651                 *len = cell->bytes;
1652
1653         return 0;
1654 }
1655
1656 /**
1657  * nvmem_cell_read() - Read a given nvmem cell
1658  *
1659  * @cell: nvmem cell to be read.
1660  * @len: pointer to length of cell which will be populated on successful read;
1661  *       can be NULL.
1662  *
1663  * Return: ERR_PTR() on error or a valid pointer to a buffer on success. The
1664  * buffer should be freed by the consumer with a kfree().
1665  */
1666 void *nvmem_cell_read(struct nvmem_cell *cell, size_t *len)
1667 {
1668         struct nvmem_cell_entry *entry = cell->entry;
1669         struct nvmem_device *nvmem = entry->nvmem;
1670         u8 *buf;
1671         int rc;
1672
1673         if (!nvmem)
1674                 return ERR_PTR(-EINVAL);
1675
1676         buf = kzalloc(max_t(size_t, entry->raw_len, entry->bytes), GFP_KERNEL);
1677         if (!buf)
1678                 return ERR_PTR(-ENOMEM);
1679
1680         rc = __nvmem_cell_read(nvmem, cell->entry, buf, len, cell->id, cell->index);
1681         if (rc) {
1682                 kfree(buf);
1683                 return ERR_PTR(rc);
1684         }
1685
1686         return buf;
1687 }
1688 EXPORT_SYMBOL_GPL(nvmem_cell_read);
1689
1690 static void *nvmem_cell_prepare_write_buffer(struct nvmem_cell_entry *cell,
1691                                              u8 *_buf, int len)
1692 {
1693         struct nvmem_device *nvmem = cell->nvmem;
1694         int i, rc, nbits, bit_offset = cell->bit_offset;
1695         u8 v, *p, *buf, *b, pbyte, pbits;
1696
1697         nbits = cell->nbits;
1698         buf = kzalloc(cell->bytes, GFP_KERNEL);
1699         if (!buf)
1700                 return ERR_PTR(-ENOMEM);
1701
1702         memcpy(buf, _buf, len);
1703         p = b = buf;
1704
1705         if (bit_offset) {
1706                 pbyte = *b;
1707                 *b <<= bit_offset;
1708
1709                 /* setup the first byte with lsb bits from nvmem */
1710                 rc = nvmem_reg_read(nvmem, cell->offset, &v, 1);
1711                 if (rc)
1712                         goto err;
1713                 *b++ |= GENMASK(bit_offset - 1, 0) & v;
1714
1715                 /* setup rest of the byte if any */
1716                 for (i = 1; i < cell->bytes; i++) {
1717                         /* Get last byte bits and shift them towards lsb */
1718                         pbits = pbyte >> (BITS_PER_BYTE - 1 - bit_offset);
1719                         pbyte = *b;
1720                         p = b;
1721                         *b <<= bit_offset;
1722                         *b++ |= pbits;
1723                 }
1724         }
1725
1726         /* if it's not end on byte boundary */
1727         if ((nbits + bit_offset) % BITS_PER_BYTE) {
1728                 /* setup the last byte with msb bits from nvmem */
1729                 rc = nvmem_reg_read(nvmem,
1730                                     cell->offset + cell->bytes - 1, &v, 1);
1731                 if (rc)
1732                         goto err;
1733                 *p |= GENMASK(7, (nbits + bit_offset) % BITS_PER_BYTE) & v;
1734
1735         }
1736
1737         return buf;
1738 err:
1739         kfree(buf);
1740         return ERR_PTR(rc);
1741 }
1742
1743 static int __nvmem_cell_entry_write(struct nvmem_cell_entry *cell, void *buf, size_t len)
1744 {
1745         struct nvmem_device *nvmem = cell->nvmem;
1746         int rc;
1747
1748         if (!nvmem || nvmem->read_only ||
1749             (cell->bit_offset == 0 && len != cell->bytes))
1750                 return -EINVAL;
1751
1752         /*
1753          * Any cells which have a read_post_process hook are read-only because
1754          * we cannot reverse the operation and it might affect other cells,
1755          * too.
1756          */
1757         if (cell->read_post_process)
1758                 return -EINVAL;
1759
1760         if (cell->bit_offset || cell->nbits) {
1761                 buf = nvmem_cell_prepare_write_buffer(cell, buf, len);
1762                 if (IS_ERR(buf))
1763                         return PTR_ERR(buf);
1764         }
1765
1766         rc = nvmem_reg_write(nvmem, cell->offset, buf, cell->bytes);
1767
1768         /* free the tmp buffer */
1769         if (cell->bit_offset || cell->nbits)
1770                 kfree(buf);
1771
1772         if (rc)
1773                 return rc;
1774
1775         return len;
1776 }
1777
1778 /**
1779  * nvmem_cell_write() - Write to a given nvmem cell
1780  *
1781  * @cell: nvmem cell to be written.
1782  * @buf: Buffer to be written.
1783  * @len: length of buffer to be written to nvmem cell.
1784  *
1785  * Return: length of bytes written or negative on failure.
1786  */
1787 int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len)
1788 {
1789         return __nvmem_cell_entry_write(cell->entry, buf, len);
1790 }
1791
1792 EXPORT_SYMBOL_GPL(nvmem_cell_write);
1793
1794 static int nvmem_cell_read_common(struct device *dev, const char *cell_id,
1795                                   void *val, size_t count)
1796 {
1797         struct nvmem_cell *cell;
1798         void *buf;
1799         size_t len;
1800
1801         cell = nvmem_cell_get(dev, cell_id);
1802         if (IS_ERR(cell))
1803                 return PTR_ERR(cell);
1804
1805         buf = nvmem_cell_read(cell, &len);
1806         if (IS_ERR(buf)) {
1807                 nvmem_cell_put(cell);
1808                 return PTR_ERR(buf);
1809         }
1810         if (len != count) {
1811                 kfree(buf);
1812                 nvmem_cell_put(cell);
1813                 return -EINVAL;
1814         }
1815         memcpy(val, buf, count);
1816         kfree(buf);
1817         nvmem_cell_put(cell);
1818
1819         return 0;
1820 }
1821
1822 /**
1823  * nvmem_cell_read_u8() - Read a cell value as a u8
1824  *
1825  * @dev: Device that requests the nvmem cell.
1826  * @cell_id: Name of nvmem cell to read.
1827  * @val: pointer to output value.
1828  *
1829  * Return: 0 on success or negative errno.
1830  */
1831 int nvmem_cell_read_u8(struct device *dev, const char *cell_id, u8 *val)
1832 {
1833         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1834 }
1835 EXPORT_SYMBOL_GPL(nvmem_cell_read_u8);
1836
1837 /**
1838  * nvmem_cell_read_u16() - Read a cell value as a u16
1839  *
1840  * @dev: Device that requests the nvmem cell.
1841  * @cell_id: Name of nvmem cell to read.
1842  * @val: pointer to output value.
1843  *
1844  * Return: 0 on success or negative errno.
1845  */
1846 int nvmem_cell_read_u16(struct device *dev, const char *cell_id, u16 *val)
1847 {
1848         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1849 }
1850 EXPORT_SYMBOL_GPL(nvmem_cell_read_u16);
1851
1852 /**
1853  * nvmem_cell_read_u32() - Read a cell value as a u32
1854  *
1855  * @dev: Device that requests the nvmem cell.
1856  * @cell_id: Name of nvmem cell to read.
1857  * @val: pointer to output value.
1858  *
1859  * Return: 0 on success or negative errno.
1860  */
1861 int nvmem_cell_read_u32(struct device *dev, const char *cell_id, u32 *val)
1862 {
1863         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1864 }
1865 EXPORT_SYMBOL_GPL(nvmem_cell_read_u32);
1866
1867 /**
1868  * nvmem_cell_read_u64() - Read a cell value as a u64
1869  *
1870  * @dev: Device that requests the nvmem cell.
1871  * @cell_id: Name of nvmem cell to read.
1872  * @val: pointer to output value.
1873  *
1874  * Return: 0 on success or negative errno.
1875  */
1876 int nvmem_cell_read_u64(struct device *dev, const char *cell_id, u64 *val)
1877 {
1878         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1879 }
1880 EXPORT_SYMBOL_GPL(nvmem_cell_read_u64);
1881
1882 static const void *nvmem_cell_read_variable_common(struct device *dev,
1883                                                    const char *cell_id,
1884                                                    size_t max_len, size_t *len)
1885 {
1886         struct nvmem_cell *cell;
1887         int nbits;
1888         void *buf;
1889
1890         cell = nvmem_cell_get(dev, cell_id);
1891         if (IS_ERR(cell))
1892                 return cell;
1893
1894         nbits = cell->entry->nbits;
1895         buf = nvmem_cell_read(cell, len);
1896         nvmem_cell_put(cell);
1897         if (IS_ERR(buf))
1898                 return buf;
1899
1900         /*
1901          * If nbits is set then nvmem_cell_read() can significantly exaggerate
1902          * the length of the real data. Throw away the extra junk.
1903          */
1904         if (nbits)
1905                 *len = DIV_ROUND_UP(nbits, 8);
1906
1907         if (*len > max_len) {
1908                 kfree(buf);
1909                 return ERR_PTR(-ERANGE);
1910         }
1911
1912         return buf;
1913 }
1914
1915 /**
1916  * nvmem_cell_read_variable_le_u32() - Read up to 32-bits of data as a little endian number.
1917  *
1918  * @dev: Device that requests the nvmem cell.
1919  * @cell_id: Name of nvmem cell to read.
1920  * @val: pointer to output value.
1921  *
1922  * Return: 0 on success or negative errno.
1923  */
1924 int nvmem_cell_read_variable_le_u32(struct device *dev, const char *cell_id,
1925                                     u32 *val)
1926 {
1927         size_t len;
1928         const u8 *buf;
1929         int i;
1930
1931         buf = nvmem_cell_read_variable_common(dev, cell_id, sizeof(*val), &len);
1932         if (IS_ERR(buf))
1933                 return PTR_ERR(buf);
1934
1935         /* Copy w/ implicit endian conversion */
1936         *val = 0;
1937         for (i = 0; i < len; i++)
1938                 *val |= buf[i] << (8 * i);
1939
1940         kfree(buf);
1941
1942         return 0;
1943 }
1944 EXPORT_SYMBOL_GPL(nvmem_cell_read_variable_le_u32);
1945
1946 /**
1947  * nvmem_cell_read_variable_le_u64() - Read up to 64-bits of data as a little endian number.
1948  *
1949  * @dev: Device that requests the nvmem cell.
1950  * @cell_id: Name of nvmem cell to read.
1951  * @val: pointer to output value.
1952  *
1953  * Return: 0 on success or negative errno.
1954  */
1955 int nvmem_cell_read_variable_le_u64(struct device *dev, const char *cell_id,
1956                                     u64 *val)
1957 {
1958         size_t len;
1959         const u8 *buf;
1960         int i;
1961
1962         buf = nvmem_cell_read_variable_common(dev, cell_id, sizeof(*val), &len);
1963         if (IS_ERR(buf))
1964                 return PTR_ERR(buf);
1965
1966         /* Copy w/ implicit endian conversion */
1967         *val = 0;
1968         for (i = 0; i < len; i++)
1969                 *val |= (uint64_t)buf[i] << (8 * i);
1970
1971         kfree(buf);
1972
1973         return 0;
1974 }
1975 EXPORT_SYMBOL_GPL(nvmem_cell_read_variable_le_u64);
1976
1977 /**
1978  * nvmem_device_cell_read() - Read a given nvmem device and cell
1979  *
1980  * @nvmem: nvmem device to read from.
1981  * @info: nvmem cell info to be read.
1982  * @buf: buffer pointer which will be populated on successful read.
1983  *
1984  * Return: length of successful bytes read on success and negative
1985  * error code on error.
1986  */
1987 ssize_t nvmem_device_cell_read(struct nvmem_device *nvmem,
1988                            struct nvmem_cell_info *info, void *buf)
1989 {
1990         struct nvmem_cell_entry cell;
1991         int rc;
1992         ssize_t len;
1993
1994         if (!nvmem)
1995                 return -EINVAL;
1996
1997         rc = nvmem_cell_info_to_nvmem_cell_entry_nodup(nvmem, info, &cell);
1998         if (rc)
1999                 return rc;
2000
2001         rc = __nvmem_cell_read(nvmem, &cell, buf, &len, NULL, 0);
2002         if (rc)
2003                 return rc;
2004
2005         return len;
2006 }
2007 EXPORT_SYMBOL_GPL(nvmem_device_cell_read);
2008
2009 /**
2010  * nvmem_device_cell_write() - Write cell to a given nvmem device
2011  *
2012  * @nvmem: nvmem device to be written to.
2013  * @info: nvmem cell info to be written.
2014  * @buf: buffer to be written to cell.
2015  *
2016  * Return: length of bytes written or negative error code on failure.
2017  */
2018 int nvmem_device_cell_write(struct nvmem_device *nvmem,
2019                             struct nvmem_cell_info *info, void *buf)
2020 {
2021         struct nvmem_cell_entry cell;
2022         int rc;
2023
2024         if (!nvmem)
2025                 return -EINVAL;
2026
2027         rc = nvmem_cell_info_to_nvmem_cell_entry_nodup(nvmem, info, &cell);
2028         if (rc)
2029                 return rc;
2030
2031         return __nvmem_cell_entry_write(&cell, buf, cell.bytes);
2032 }
2033 EXPORT_SYMBOL_GPL(nvmem_device_cell_write);
2034
2035 /**
2036  * nvmem_device_read() - Read from a given nvmem device
2037  *
2038  * @nvmem: nvmem device to read from.
2039  * @offset: offset in nvmem device.
2040  * @bytes: number of bytes to read.
2041  * @buf: buffer pointer which will be populated on successful read.
2042  *
2043  * Return: length of successful bytes read on success and negative
2044  * error code on error.
2045  */
2046 int nvmem_device_read(struct nvmem_device *nvmem,
2047                       unsigned int offset,
2048                       size_t bytes, void *buf)
2049 {
2050         int rc;
2051
2052         if (!nvmem)
2053                 return -EINVAL;
2054
2055         rc = nvmem_reg_read(nvmem, offset, buf, bytes);
2056
2057         if (rc)
2058                 return rc;
2059
2060         return bytes;
2061 }
2062 EXPORT_SYMBOL_GPL(nvmem_device_read);
2063
2064 /**
2065  * nvmem_device_write() - Write cell to a given nvmem device
2066  *
2067  * @nvmem: nvmem device to be written to.
2068  * @offset: offset in nvmem device.
2069  * @bytes: number of bytes to write.
2070  * @buf: buffer to be written.
2071  *
2072  * Return: length of bytes written or negative error code on failure.
2073  */
2074 int nvmem_device_write(struct nvmem_device *nvmem,
2075                        unsigned int offset,
2076                        size_t bytes, void *buf)
2077 {
2078         int rc;
2079
2080         if (!nvmem)
2081                 return -EINVAL;
2082
2083         rc = nvmem_reg_write(nvmem, offset, buf, bytes);
2084
2085         if (rc)
2086                 return rc;
2087
2088
2089         return bytes;
2090 }
2091 EXPORT_SYMBOL_GPL(nvmem_device_write);
2092
2093 /**
2094  * nvmem_add_cell_table() - register a table of cell info entries
2095  *
2096  * @table: table of cell info entries
2097  */
2098 void nvmem_add_cell_table(struct nvmem_cell_table *table)
2099 {
2100         mutex_lock(&nvmem_cell_mutex);
2101         list_add_tail(&table->node, &nvmem_cell_tables);
2102         mutex_unlock(&nvmem_cell_mutex);
2103 }
2104 EXPORT_SYMBOL_GPL(nvmem_add_cell_table);
2105
2106 /**
2107  * nvmem_del_cell_table() - remove a previously registered cell info table
2108  *
2109  * @table: table of cell info entries
2110  */
2111 void nvmem_del_cell_table(struct nvmem_cell_table *table)
2112 {
2113         mutex_lock(&nvmem_cell_mutex);
2114         list_del(&table->node);
2115         mutex_unlock(&nvmem_cell_mutex);
2116 }
2117 EXPORT_SYMBOL_GPL(nvmem_del_cell_table);
2118
2119 /**
2120  * nvmem_add_cell_lookups() - register a list of cell lookup entries
2121  *
2122  * @entries: array of cell lookup entries
2123  * @nentries: number of cell lookup entries in the array
2124  */
2125 void nvmem_add_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
2126 {
2127         int i;
2128
2129         mutex_lock(&nvmem_lookup_mutex);
2130         for (i = 0; i < nentries; i++)
2131                 list_add_tail(&entries[i].node, &nvmem_lookup_list);
2132         mutex_unlock(&nvmem_lookup_mutex);
2133 }
2134 EXPORT_SYMBOL_GPL(nvmem_add_cell_lookups);
2135
2136 /**
2137  * nvmem_del_cell_lookups() - remove a list of previously added cell lookup
2138  *                            entries
2139  *
2140  * @entries: array of cell lookup entries
2141  * @nentries: number of cell lookup entries in the array
2142  */
2143 void nvmem_del_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
2144 {
2145         int i;
2146
2147         mutex_lock(&nvmem_lookup_mutex);
2148         for (i = 0; i < nentries; i++)
2149                 list_del(&entries[i].node);
2150         mutex_unlock(&nvmem_lookup_mutex);
2151 }
2152 EXPORT_SYMBOL_GPL(nvmem_del_cell_lookups);
2153
2154 /**
2155  * nvmem_dev_name() - Get the name of a given nvmem device.
2156  *
2157  * @nvmem: nvmem device.
2158  *
2159  * Return: name of the nvmem device.
2160  */
2161 const char *nvmem_dev_name(struct nvmem_device *nvmem)
2162 {
2163         return dev_name(&nvmem->dev);
2164 }
2165 EXPORT_SYMBOL_GPL(nvmem_dev_name);
2166
2167 /**
2168  * nvmem_dev_size() - Get the size of a given nvmem device.
2169  *
2170  * @nvmem: nvmem device.
2171  *
2172  * Return: size of the nvmem device.
2173  */
2174 size_t nvmem_dev_size(struct nvmem_device *nvmem)
2175 {
2176         return nvmem->size;
2177 }
2178 EXPORT_SYMBOL_GPL(nvmem_dev_size);
2179
2180 static int __init nvmem_init(void)
2181 {
2182         int ret;
2183
2184         ret = bus_register(&nvmem_bus_type);
2185         if (ret)
2186                 return ret;
2187
2188         ret = nvmem_layout_bus_register();
2189         if (ret)
2190                 bus_unregister(&nvmem_bus_type);
2191
2192         return ret;
2193 }
2194
2195 static void __exit nvmem_exit(void)
2196 {
2197         nvmem_layout_bus_unregister();
2198         bus_unregister(&nvmem_bus_type);
2199 }
2200
2201 subsys_initcall(nvmem_init);
2202 module_exit(nvmem_exit);
2203
2204 MODULE_AUTHOR("Srinivas Kandagatla <srinivas.kandagatla@linaro.org");
2205 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com");
2206 MODULE_DESCRIPTION("nvmem Driver Core");