drivers/nvmem/core.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * nvmem framework core.
   4  *
   5  * Copyright (C) 2015 Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
   6  * Copyright (C) 2013 Maxime Ripard <maxime.ripard@free-electrons.com>
   7  */
   8
   9 #include <linux/device.h>
  10 #include <linux/export.h>
  11 #include <linux/fs.h>
  12 #include <linux/idr.h>
  13 #include <linux/init.h>
  14 #include <linux/kref.h>
  15 #include <linux/module.h>
  16 #include <linux/nvmem-consumer.h>
  17 #include <linux/nvmem-provider.h>
  18 #include <linux/gpio/consumer.h>
  19 #include <linux/of.h>
  20 #include <linux/slab.h>
  21
  22 struct nvmem_device {
  23         struct module           *owner;
  24         struct device           dev;
  25         int                     stride;
  26         int                     word_size;
  27         int                     id;
  28         struct kref             refcnt;
  29         size_t                  size;
  30         bool                    read_only;
  31         bool                    root_only;
  32         int                     flags;
  33         enum nvmem_type         type;
  34         struct bin_attribute    eeprom;
  35         struct device           *base_dev;
  36         struct list_head        cells;
  37         const struct nvmem_keepout *keepout;
  38         unsigned int            nkeepout;
  39         nvmem_reg_read_t        reg_read;
  40         nvmem_reg_write_t       reg_write;
  41         struct gpio_desc        *wp_gpio;
  42         void *priv;
  43 };
  44
  45 #define to_nvmem_device(d) container_of(d, struct nvmem_device, dev)
  46
  47 #define FLAG_COMPAT             BIT(0)
  48
  49 struct nvmem_cell {
  50         const char              *name;
  51         int                     offset;
  52         int                     bytes;
  53         int                     bit_offset;
  54         int                     nbits;
  55         struct device_node      *np;
  56         struct nvmem_device     *nvmem;
  57         struct list_head        node;
  58 };
  59
  60 static DEFINE_MUTEX(nvmem_mutex);
  61 static DEFINE_IDA(nvmem_ida);
  62
  63 static DEFINE_MUTEX(nvmem_cell_mutex);
  64 static LIST_HEAD(nvmem_cell_tables);
  65
  66 static DEFINE_MUTEX(nvmem_lookup_mutex);
  67 static LIST_HEAD(nvmem_lookup_list);
  68
  69 static BLOCKING_NOTIFIER_HEAD(nvmem_notifier);
  70
  71 static int __nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
  72                             void *val, size_t bytes)
  73 {
  74         if (nvmem->reg_read)
  75                 return nvmem->reg_read(nvmem->priv, offset, val, bytes);
  76
  77         return -EINVAL;
  78 }
  79
  80 static int __nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
  81                              void *val, size_t bytes)
  82 {
  83         int ret;
  84
  85         if (nvmem->reg_write) {
  86                 gpiod_set_value_cansleep(nvmem->wp_gpio, 0);
  87                 ret = nvmem->reg_write(nvmem->priv, offset, val, bytes);
  88                 gpiod_set_value_cansleep(nvmem->wp_gpio, 1);
  89                 return ret;
  90         }
  91
  92         return -EINVAL;
  93 }
  94
  95 static int nvmem_access_with_keepouts(struct nvmem_device *nvmem,
  96                                       unsigned int offset, void *val,
  97                                       size_t bytes, int write)
  98 {
  99
 100         unsigned int end = offset + bytes;
 101         unsigned int kend, ksize;
 102         const struct nvmem_keepout *keepout = nvmem->keepout;
 103         const struct nvmem_keepout *keepoutend = keepout + nvmem->nkeepout;
 104         int rc;
 105
 106         /*
 107          * Skip all keepouts before the range being accessed.
 108          * Keepouts are sorted.
 109          */
 110         while ((keepout < keepoutend) && (keepout->end <= offset))
 111                 keepout++;
 112
 113         while ((offset < end) && (keepout < keepoutend)) {
 114                 /* Access the valid portion before the keepout. */
 115                 if (offset < keepout->start) {
 116                         kend = min(end, keepout->start);
 117                         ksize = kend - offset;
 118                         if (write)
 119                                 rc = __nvmem_reg_write(nvmem, offset, val, ksize);
 120                         else
 121                                 rc = __nvmem_reg_read(nvmem, offset, val, ksize);
 122
 123                         if (rc)
 124                                 return rc;
 125
 126                         offset += ksize;
 127                         val += ksize;
 128                 }
 129
 130                 /*
 131                  * Now we're aligned to the start of this keepout zone. Go
 132                  * through it.
 133                  */
 134                 kend = min(end, keepout->end);
 135                 ksize = kend - offset;
 136                 if (!write)
 137                         memset(val, keepout->value, ksize);
 138
 139                 val += ksize;
 140                 offset += ksize;
 141                 keepout++;
 142         }
 143
 144         /*
 145          * If we ran out of keepouts but there's still stuff to do, send it
 146          * down directly
 147          */
 148         if (offset < end) {
 149                 ksize = end - offset;
 150                 if (write)
 151                         return __nvmem_reg_write(nvmem, offset, val, ksize);
 152                 else
 153                         return __nvmem_reg_read(nvmem, offset, val, ksize);
 154         }
 155
 156         return 0;
 157 }
 158
 159 static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
 160                           void *val, size_t bytes)
 161 {
 162         if (!nvmem->nkeepout)
 163                 return __nvmem_reg_read(nvmem, offset, val, bytes);
 164
 165         return nvmem_access_with_keepouts(nvmem, offset, val, bytes, false);
 166 }
 167
 168 static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
 169                            void *val, size_t bytes)
 170 {
 171         if (!nvmem->nkeepout)
 172                 return __nvmem_reg_write(nvmem, offset, val, bytes);
 173
 174         return nvmem_access_with_keepouts(nvmem, offset, val, bytes, true);
 175 }
 176
 177 #ifdef CONFIG_NVMEM_SYSFS
 178 static const char * const nvmem_type_str[] = {
 179         [NVMEM_TYPE_UNKNOWN] = "Unknown",
 180         [NVMEM_TYPE_EEPROM] = "EEPROM",
 181         [NVMEM_TYPE_OTP] = "OTP",
 182         [NVMEM_TYPE_BATTERY_BACKED] = "Battery backed",
 183         [NVMEM_TYPE_FRAM] = "FRAM",
 184 };
 185
 186 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 187 static struct lock_class_key eeprom_lock_key;
 188 #endif
 189
 190 static ssize_t type_show(struct device *dev,
 191                          struct device_attribute *attr, char *buf)
 192 {
 193         struct nvmem_device *nvmem = to_nvmem_device(dev);
 194
 195         return sprintf(buf, "%s\n", nvmem_type_str[nvmem->type]);
 196 }
 197
 198 static DEVICE_ATTR_RO(type);
 199
 200 static struct attribute *nvmem_attrs[] = {
 201         &dev_attr_type.attr,
 202         NULL,
 203 };
 204
 205 static ssize_t bin_attr_nvmem_read(struct file *filp, struct kobject *kobj,
 206                                    struct bin_attribute *attr, char *buf,
 207                                    loff_t pos, size_t count)
 208 {
 209         struct device *dev;
 210         struct nvmem_device *nvmem;
 211         int rc;
 212
 213         if (attr->private)
 214                 dev = attr->private;
 215         else
 216                 dev = kobj_to_dev(kobj);
 217         nvmem = to_nvmem_device(dev);
 218
 219         /* Stop the user from reading */
 220         if (pos >= nvmem->size)
 221                 return 0;
 222
 223         if (!IS_ALIGNED(pos, nvmem->stride))
 224                 return -EINVAL;
 225
 226         if (count < nvmem->word_size)
 227                 return -EINVAL;
 228
 229         if (pos + count > nvmem->size)
 230                 count = nvmem->size - pos;
 231
 232         count = round_down(count, nvmem->word_size);
 233
 234         if (!nvmem->reg_read)
 235                 return -EPERM;
 236
 237         rc = nvmem_reg_read(nvmem, pos, buf, count);
 238
 239         if (rc)
 240                 return rc;
 241
 242         return count;
 243 }
 244
 245 static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj,
 246                                     struct bin_attribute *attr, char *buf,
 247                                     loff_t pos, size_t count)
 248 {
 249         struct device *dev;
 250         struct nvmem_device *nvmem;
 251         int rc;
 252
 253         if (attr->private)
 254                 dev = attr->private;
 255         else
 256                 dev = kobj_to_dev(kobj);
 257         nvmem = to_nvmem_device(dev);
 258
 259         /* Stop the user from writing */
 260         if (pos >= nvmem->size)
 261                 return -EFBIG;
 262
 263         if (!IS_ALIGNED(pos, nvmem->stride))
 264                 return -EINVAL;
 265
 266         if (count < nvmem->word_size)
 267                 return -EINVAL;
 268
 269         if (pos + count > nvmem->size)
 270                 count = nvmem->size - pos;
 271
 272         count = round_down(count, nvmem->word_size);
 273
 274         if (!nvmem->reg_write)
 275                 return -EPERM;
 276
 277         rc = nvmem_reg_write(nvmem, pos, buf, count);
 278
 279         if (rc)
 280                 return rc;
 281
 282         return count;
 283 }
 284
 285 static umode_t nvmem_bin_attr_get_umode(struct nvmem_device *nvmem)
 286 {
 287         umode_t mode = 0400;
 288
 289         if (!nvmem->root_only)
 290                 mode |= 0044;
 291
 292         if (!nvmem->read_only)
 293                 mode |= 0200;
 294
 295         if (!nvmem->reg_write)
 296                 mode &= ~0200;
 297
 298         if (!nvmem->reg_read)
 299                 mode &= ~0444;
 300
 301         return mode;
 302 }
 303
 304 static umode_t nvmem_bin_attr_is_visible(struct kobject *kobj,
 305                                          struct bin_attribute *attr, int i)
 306 {
 307         struct device *dev = kobj_to_dev(kobj);
 308         struct nvmem_device *nvmem = to_nvmem_device(dev);
 309
 310         return nvmem_bin_attr_get_umode(nvmem);
 311 }
 312
 313 /* default read/write permissions */
 314 static struct bin_attribute bin_attr_rw_nvmem = {
 315         .attr   = {
 316                 .name   = "nvmem",
 317                 .mode   = 0644,
 318         },
 319         .read   = bin_attr_nvmem_read,
 320         .write  = bin_attr_nvmem_write,
 321 };
 322
 323 static struct bin_attribute *nvmem_bin_attributes[] = {
 324         &bin_attr_rw_nvmem,
 325         NULL,
 326 };
 327
 328 static const struct attribute_group nvmem_bin_group = {
 329         .bin_attrs      = nvmem_bin_attributes,
 330         .attrs          = nvmem_attrs,
 331         .is_bin_visible = nvmem_bin_attr_is_visible,
 332 };
 333
 334 static const struct attribute_group *nvmem_dev_groups[] = {
 335         &nvmem_bin_group,
 336         NULL,
 337 };
 338
 339 static struct bin_attribute bin_attr_nvmem_eeprom_compat = {
 340         .attr   = {
 341                 .name   = "eeprom",
 342         },
 343         .read   = bin_attr_nvmem_read,
 344         .write  = bin_attr_nvmem_write,
 345 };
 346
 347 /*
 348  * nvmem_setup_compat() - Create an additional binary entry in
 349  * drivers sys directory, to be backwards compatible with the older
 350  * drivers/misc/eeprom drivers.
 351  */
 352 static int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
 353                                     const struct nvmem_config *config)
 354 {
 355         int rval;
 356
 357         if (!config->compat)
 358                 return 0;
 359
 360         if (!config->base_dev)
 361                 return -EINVAL;
 362
 363         if (config->type == NVMEM_TYPE_FRAM)
 364                 bin_attr_nvmem_eeprom_compat.attr.name = "fram";
 365
 366         nvmem->eeprom = bin_attr_nvmem_eeprom_compat;
 367         nvmem->eeprom.attr.mode = nvmem_bin_attr_get_umode(nvmem);
 368         nvmem->eeprom.size = nvmem->size;
 369 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 370         nvmem->eeprom.attr.key = &eeprom_lock_key;
 371 #endif
 372         nvmem->eeprom.private = &nvmem->dev;
 373         nvmem->base_dev = config->base_dev;
 374
 375         rval = device_create_bin_file(nvmem->base_dev, &nvmem->eeprom);
 376         if (rval) {
 377                 dev_err(&nvmem->dev,
 378                         "Failed to create eeprom binary file %d\n", rval);
 379                 return rval;
 380         }
 381
 382         nvmem->flags |= FLAG_COMPAT;
 383
 384         return 0;
 385 }
 386
 387 static void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem,
 388                               const struct nvmem_config *config)
 389 {
 390         if (config->compat)
 391                 device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
 392 }
 393
 394 #else /* CONFIG_NVMEM_SYSFS */
 395
 396 static int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
 397                                     const struct nvmem_config *config)
 398 {
 399         return -ENOSYS;
 400 }
 401 static void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem,
 402                                       const struct nvmem_config *config)
 403 {
 404 }
 405
 406 #endif /* CONFIG_NVMEM_SYSFS */
 407
 408 static void nvmem_release(struct device *dev)
 409 {
 410         struct nvmem_device *nvmem = to_nvmem_device(dev);
 411
 412         ida_free(&nvmem_ida, nvmem->id);
 413         gpiod_put(nvmem->wp_gpio);
 414         kfree(nvmem);
 415 }
 416
 417 static const struct device_type nvmem_provider_type = {
 418         .release        = nvmem_release,
 419 };
 420
 421 static struct bus_type nvmem_bus_type = {
 422         .name           = "nvmem",
 423 };
 424
 425 static void nvmem_cell_drop(struct nvmem_cell *cell)
 426 {
 427         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_REMOVE, cell);
 428         mutex_lock(&nvmem_mutex);
 429         list_del(&cell->node);
 430         mutex_unlock(&nvmem_mutex);
 431         of_node_put(cell->np);
 432         kfree_const(cell->name);
 433         kfree(cell);
 434 }
 435
 436 static void nvmem_device_remove_all_cells(const struct nvmem_device *nvmem)
 437 {
 438         struct nvmem_cell *cell, *p;
 439
 440         list_for_each_entry_safe(cell, p, &nvmem->cells, node)
 441                 nvmem_cell_drop(cell);
 442 }
 443
 444 static void nvmem_cell_add(struct nvmem_cell *cell)
 445 {
 446         mutex_lock(&nvmem_mutex);
 447         list_add_tail(&cell->node, &cell->nvmem->cells);
 448         mutex_unlock(&nvmem_mutex);
 449         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_ADD, cell);
 450 }
 451
 452 static int nvmem_cell_info_to_nvmem_cell_nodup(struct nvmem_device *nvmem,
 453                                         const struct nvmem_cell_info *info,
 454                                         struct nvmem_cell *cell)
 455 {
 456         cell->nvmem = nvmem;
 457         cell->offset = info->offset;
 458         cell->bytes = info->bytes;
 459         cell->name = info->name;
 460
 461         cell->bit_offset = info->bit_offset;
 462         cell->nbits = info->nbits;
 463
 464         if (cell->nbits)
 465                 cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
 466                                            BITS_PER_BYTE);
 467
 468         if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
 469                 dev_err(&nvmem->dev,
 470                         "cell %s unaligned to nvmem stride %d\n",
 471                         cell->name ?: "<unknown>", nvmem->stride);
 472                 return -EINVAL;
 473         }
 474
 475         return 0;
 476 }
 477
 478 static int nvmem_cell_info_to_nvmem_cell(struct nvmem_device *nvmem,
 479                                 const struct nvmem_cell_info *info,
 480                                 struct nvmem_cell *cell)
 481 {
 482         int err;
 483
 484         err = nvmem_cell_info_to_nvmem_cell_nodup(nvmem, info, cell);
 485         if (err)
 486                 return err;
 487
 488         cell->name = kstrdup_const(info->name, GFP_KERNEL);
 489         if (!cell->name)
 490                 return -ENOMEM;
 491
 492         return 0;
 493 }
 494
 495 /**
 496  * nvmem_add_cells() - Add cell information to an nvmem device
 497  *
 498  * @nvmem: nvmem device to add cells to.
 499  * @info: nvmem cell info to add to the device
 500  * @ncells: number of cells in info
 501  *
 502  * Return: 0 or negative error code on failure.
 503  */
 504 static int nvmem_add_cells(struct nvmem_device *nvmem,
 505                     const struct nvmem_cell_info *info,
 506                     int ncells)
 507 {
 508         struct nvmem_cell **cells;
 509         int i, rval;
 510
 511         cells = kcalloc(ncells, sizeof(*cells), GFP_KERNEL);
 512         if (!cells)
 513                 return -ENOMEM;
 514
 515         for (i = 0; i < ncells; i++) {
 516                 cells[i] = kzalloc(sizeof(**cells), GFP_KERNEL);
 517                 if (!cells[i]) {
 518                         rval = -ENOMEM;
 519                         goto err;
 520                 }
 521
 522                 rval = nvmem_cell_info_to_nvmem_cell(nvmem, &info[i], cells[i]);
 523                 if (rval) {
 524                         kfree(cells[i]);
 525                         goto err;
 526                 }
 527
 528                 nvmem_cell_add(cells[i]);
 529         }
 530
 531         /* remove tmp array */
 532         kfree(cells);
 533
 534         return 0;
 535 err:
 536         while (i--)
 537                 nvmem_cell_drop(cells[i]);
 538
 539         kfree(cells);
 540
 541         return rval;
 542 }
 543
 544 /**
 545  * nvmem_register_notifier() - Register a notifier block for nvmem events.
 546  *
 547  * @nb: notifier block to be called on nvmem events.
 548  *
 549  * Return: 0 on success, negative error number on failure.
 550  */
 551 int nvmem_register_notifier(struct notifier_block *nb)
 552 {
 553         return blocking_notifier_chain_register(&nvmem_notifier, nb);
 554 }
 555 EXPORT_SYMBOL_GPL(nvmem_register_notifier);
 556
 557 /**
 558  * nvmem_unregister_notifier() - Unregister a notifier block for nvmem events.
 559  *
 560  * @nb: notifier block to be unregistered.
 561  *
 562  * Return: 0 on success, negative error number on failure.
 563  */
 564 int nvmem_unregister_notifier(struct notifier_block *nb)
 565 {
 566         return blocking_notifier_chain_unregister(&nvmem_notifier, nb);
 567 }
 568 EXPORT_SYMBOL_GPL(nvmem_unregister_notifier);
 569
 570 static int nvmem_add_cells_from_table(struct nvmem_device *nvmem)
 571 {
 572         const struct nvmem_cell_info *info;
 573         struct nvmem_cell_table *table;
 574         struct nvmem_cell *cell;
 575         int rval = 0, i;
 576
 577         mutex_lock(&nvmem_cell_mutex);
 578         list_for_each_entry(table, &nvmem_cell_tables, node) {
 579                 if (strcmp(nvmem_dev_name(nvmem), table->nvmem_name) == 0) {
 580                         for (i = 0; i < table->ncells; i++) {
 581                                 info = &table->cells[i];
 582
 583                                 cell = kzalloc(sizeof(*cell), GFP_KERNEL);
 584                                 if (!cell) {
 585                                         rval = -ENOMEM;
 586                                         goto out;
 587                                 }
 588
 589                                 rval = nvmem_cell_info_to_nvmem_cell(nvmem,
 590                                                                      info,
 591                                                                      cell);
 592                                 if (rval) {
 593                                         kfree(cell);
 594                                         goto out;
 595                                 }
 596
 597                                 nvmem_cell_add(cell);
 598                         }
 599                 }
 600         }
 601
 602 out:
 603         mutex_unlock(&nvmem_cell_mutex);
 604         return rval;
 605 }
 606
 607 static struct nvmem_cell *
 608 nvmem_find_cell_by_name(struct nvmem_device *nvmem, const char *cell_id)
 609 {
 610         struct nvmem_cell *iter, *cell = NULL;
 611
 612         mutex_lock(&nvmem_mutex);
 613         list_for_each_entry(iter, &nvmem->cells, node) {
 614                 if (strcmp(cell_id, iter->name) == 0) {
 615                         cell = iter;
 616                         break;
 617                 }
 618         }
 619         mutex_unlock(&nvmem_mutex);
 620
 621         return cell;
 622 }
 623
 624 static int nvmem_validate_keepouts(struct nvmem_device *nvmem)
 625 {
 626         unsigned int cur = 0;
 627         const struct nvmem_keepout *keepout = nvmem->keepout;
 628         const struct nvmem_keepout *keepoutend = keepout + nvmem->nkeepout;
 629
 630         while (keepout < keepoutend) {
 631                 /* Ensure keepouts are sorted and don't overlap. */
 632                 if (keepout->start < cur) {
 633                         dev_err(&nvmem->dev,
 634                                 "Keepout regions aren't sorted or overlap.\n");
 635
 636                         return -ERANGE;
 637                 }
 638
 639                 if (keepout->end < keepout->start) {
 640                         dev_err(&nvmem->dev,
 641                                 "Invalid keepout region.\n");
 642
 643                         return -EINVAL;
 644                 }
 645
 646                 /*
 647                  * Validate keepouts (and holes between) don't violate
 648                  * word_size constraints.
 649                  */
 650                 if ((keepout->end - keepout->start < nvmem->word_size) ||
 651                     ((keepout->start != cur) &&
 652                      (keepout->start - cur < nvmem->word_size))) {
 653
 654                         dev_err(&nvmem->dev,
 655                                 "Keepout regions violate word_size constraints.\n");
 656
 657                         return -ERANGE;
 658                 }
 659
 660                 /* Validate keepouts don't violate stride (alignment). */
 661                 if (!IS_ALIGNED(keepout->start, nvmem->stride) ||
 662                     !IS_ALIGNED(keepout->end, nvmem->stride)) {
 663
 664                         dev_err(&nvmem->dev,
 665                                 "Keepout regions violate stride.\n");
 666
 667                         return -EINVAL;
 668                 }
 669
 670                 cur = keepout->end;
 671                 keepout++;
 672         }
 673
 674         return 0;
 675 }
 676
 677 static int nvmem_add_cells_from_of(struct nvmem_device *nvmem)
 678 {
 679         struct device_node *parent, *child;
 680         struct device *dev = &nvmem->dev;
 681         struct nvmem_cell *cell;
 682         const __be32 *addr;
 683         int len;
 684
 685         parent = dev->of_node;
 686
 687         for_each_child_of_node(parent, child) {
 688                 addr = of_get_property(child, "reg", &len);
 689                 if (!addr)
 690                         continue;
 691                 if (len < 2 * sizeof(u32)) {
 692                         dev_err(dev, "nvmem: invalid reg on %pOF\n", child);
 693                         of_node_put(child);
 694                         return -EINVAL;
 695                 }
 696
 697                 cell = kzalloc(sizeof(*cell), GFP_KERNEL);
 698                 if (!cell) {
 699                         of_node_put(child);
 700                         return -ENOMEM;
 701                 }
 702
 703                 cell->nvmem = nvmem;
 704                 cell->offset = be32_to_cpup(addr++);
 705                 cell->bytes = be32_to_cpup(addr);
 706                 cell->name = kasprintf(GFP_KERNEL, "%pOFn", child);
 707
 708                 addr = of_get_property(child, "bits", &len);
 709                 if (addr && len == (2 * sizeof(u32))) {
 710                         cell->bit_offset = be32_to_cpup(addr++);
 711                         cell->nbits = be32_to_cpup(addr);
 712                 }
 713
 714                 if (cell->nbits)
 715                         cell->bytes = DIV_ROUND_UP(
 716                                         cell->nbits + cell->bit_offset,
 717                                         BITS_PER_BYTE);
 718
 719                 if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
 720                         dev_err(dev, "cell %s unaligned to nvmem stride %d\n",
 721                                 cell->name, nvmem->stride);
 722                         /* Cells already added will be freed later. */
 723                         kfree_const(cell->name);
 724                         kfree(cell);
 725                         of_node_put(child);
 726                         return -EINVAL;
 727                 }
 728
 729                 cell->np = of_node_get(child);
 730                 nvmem_cell_add(cell);
 731         }
 732
 733         return 0;
 734 }
 735
 736 /**
 737  * nvmem_register() - Register a nvmem device for given nvmem_config.
 738  * Also creates a binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
 739  *
 740  * @config: nvmem device configuration with which nvmem device is created.
 741  *
 742  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
 743  * on success.
 744  */
 745
 746 struct nvmem_device *nvmem_register(const struct nvmem_config *config)
 747 {
 748         struct nvmem_device *nvmem;
 749         int rval;
 750
 751         if (!config->dev)
 752                 return ERR_PTR(-EINVAL);
 753
 754         if (!config->reg_read && !config->reg_write)
 755                 return ERR_PTR(-EINVAL);
 756
 757         nvmem = kzalloc(sizeof(*nvmem), GFP_KERNEL);
 758         if (!nvmem)
 759                 return ERR_PTR(-ENOMEM);
 760
 761         rval  = ida_alloc(&nvmem_ida, GFP_KERNEL);
 762         if (rval < 0) {
 763                 kfree(nvmem);
 764                 return ERR_PTR(rval);
 765         }
 766
 767         if (config->wp_gpio)
 768                 nvmem->wp_gpio = config->wp_gpio;
 769         else
 770                 nvmem->wp_gpio = gpiod_get_optional(config->dev, "wp",
 771                                                     GPIOD_OUT_HIGH);
 772         if (IS_ERR(nvmem->wp_gpio)) {
 773                 ida_free(&nvmem_ida, nvmem->id);
 774                 rval = PTR_ERR(nvmem->wp_gpio);
 775                 kfree(nvmem);
 776                 return ERR_PTR(rval);
 777         }
 778
 779         kref_init(&nvmem->refcnt);
 780         INIT_LIST_HEAD(&nvmem->cells);
 781
 782         nvmem->id = rval;
 783         nvmem->owner = config->owner;
 784         if (!nvmem->owner && config->dev->driver)
 785                 nvmem->owner = config->dev->driver->owner;
 786         nvmem->stride = config->stride ?: 1;
 787         nvmem->word_size = config->word_size ?: 1;
 788         nvmem->size = config->size;
 789         nvmem->dev.type = &nvmem_provider_type;
 790         nvmem->dev.bus = &nvmem_bus_type;
 791         nvmem->dev.parent = config->dev;
 792         nvmem->root_only = config->root_only;
 793         nvmem->priv = config->priv;
 794         nvmem->type = config->type;
 795         nvmem->reg_read = config->reg_read;
 796         nvmem->reg_write = config->reg_write;
 797         nvmem->keepout = config->keepout;
 798         nvmem->nkeepout = config->nkeepout;
 799         if (!config->no_of_node)
 800                 nvmem->dev.of_node = config->dev->of_node;
 801
 802         switch (config->id) {
 803         case NVMEM_DEVID_NONE:
 804                 dev_set_name(&nvmem->dev, "%s", config->name);
 805                 break;
 806         case NVMEM_DEVID_AUTO:
 807                 dev_set_name(&nvmem->dev, "%s%d", config->name, nvmem->id);
 808                 break;
 809         default:
 810                 dev_set_name(&nvmem->dev, "%s%d",
 811                              config->name ? : "nvmem",
 812                              config->name ? config->id : nvmem->id);
 813                 break;
 814         }
 815
 816         nvmem->read_only = device_property_present(config->dev, "read-only") ||
 817                            config->read_only || !nvmem->reg_write;
 818
 819 #ifdef CONFIG_NVMEM_SYSFS
 820         nvmem->dev.groups = nvmem_dev_groups;
 821 #endif
 822
 823         if (nvmem->nkeepout) {
 824                 rval = nvmem_validate_keepouts(nvmem);
 825                 if (rval)
 826                         goto err_put_device;
 827         }
 828
 829         dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
 830
 831         rval = device_register(&nvmem->dev);
 832         if (rval)
 833                 goto err_put_device;
 834
 835         if (config->compat) {
 836                 rval = nvmem_sysfs_setup_compat(nvmem, config);
 837                 if (rval)
 838                         goto err_device_del;
 839         }
 840
 841         if (config->cells) {
 842                 rval = nvmem_add_cells(nvmem, config->cells, config->ncells);
 843                 if (rval)
 844                         goto err_teardown_compat;
 845         }
 846
 847         rval = nvmem_add_cells_from_table(nvmem);
 848         if (rval)
 849                 goto err_remove_cells;
 850
 851         rval = nvmem_add_cells_from_of(nvmem);
 852         if (rval)
 853                 goto err_remove_cells;
 854
 855         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem);
 856
 857         return nvmem;
 858
 859 err_remove_cells:
 860         nvmem_device_remove_all_cells(nvmem);
 861 err_teardown_compat:
 862         if (config->compat)
 863                 nvmem_sysfs_remove_compat(nvmem, config);
 864 err_device_del:
 865         device_del(&nvmem->dev);
 866 err_put_device:
 867         put_device(&nvmem->dev);
 868
 869         return ERR_PTR(rval);
 870 }
 871 EXPORT_SYMBOL_GPL(nvmem_register);
 872
 873 static void nvmem_device_release(struct kref *kref)
 874 {
 875         struct nvmem_device *nvmem;
 876
 877         nvmem = container_of(kref, struct nvmem_device, refcnt);
 878
 879         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_REMOVE, nvmem);
 880
 881         if (nvmem->flags & FLAG_COMPAT)
 882                 device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
 883
 884         nvmem_device_remove_all_cells(nvmem);
 885         device_unregister(&nvmem->dev);
 886 }
 887
 888 /**
 889  * nvmem_unregister() - Unregister previously registered nvmem device
 890  *
 891  * @nvmem: Pointer to previously registered nvmem device.
 892  */
 893 void nvmem_unregister(struct nvmem_device *nvmem)
 894 {
 895         kref_put(&nvmem->refcnt, nvmem_device_release);
 896 }
 897 EXPORT_SYMBOL_GPL(nvmem_unregister);
 898
 899 static void devm_nvmem_release(struct device *dev, void *res)
 900 {
 901         nvmem_unregister(*(struct nvmem_device **)res);
 902 }
 903
 904 /**
 905  * devm_nvmem_register() - Register a managed nvmem device for given
 906  * nvmem_config.
 907  * Also creates a binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
 908  *
 909  * @dev: Device that uses the nvmem device.
 910  * @config: nvmem device configuration with which nvmem device is created.
 911  *
 912  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
 913  * on success.
 914  */
 915 struct nvmem_device *devm_nvmem_register(struct device *dev,
 916                                          const struct nvmem_config *config)
 917 {
 918         struct nvmem_device **ptr, *nvmem;
 919
 920         ptr = devres_alloc(devm_nvmem_release, sizeof(*ptr), GFP_KERNEL);
 921         if (!ptr)
 922                 return ERR_PTR(-ENOMEM);
 923
 924         nvmem = nvmem_register(config);
 925
 926         if (!IS_ERR(nvmem)) {
 927                 *ptr = nvmem;
 928                 devres_add(dev, ptr);
 929         } else {
 930                 devres_free(ptr);
 931         }
 932
 933         return nvmem;
 934 }
 935 EXPORT_SYMBOL_GPL(devm_nvmem_register);
 936
 937 static int devm_nvmem_match(struct device *dev, void *res, void *data)
 938 {
 939         struct nvmem_device **r = res;
 940
 941         return *r == data;
 942 }
 943
 944 /**
 945  * devm_nvmem_unregister() - Unregister previously registered managed nvmem
 946  * device.
 947  *
 948  * @dev: Device that uses the nvmem device.
 949  * @nvmem: Pointer to previously registered nvmem device.
 950  *
 951  * Return: Will be negative on error or zero on success.
 952  */
 953 int devm_nvmem_unregister(struct device *dev, struct nvmem_device *nvmem)
 954 {
 955         return devres_release(dev, devm_nvmem_release, devm_nvmem_match, nvmem);
 956 }
 957 EXPORT_SYMBOL(devm_nvmem_unregister);
 958
 959 static struct nvmem_device *__nvmem_device_get(void *data,
 960                         int (*match)(struct device *dev, const void *data))
 961 {
 962         struct nvmem_device *nvmem = NULL;
 963         struct device *dev;
 964
 965         mutex_lock(&nvmem_mutex);
 966         dev = bus_find_device(&nvmem_bus_type, NULL, data, match);
 967         if (dev)
 968                 nvmem = to_nvmem_device(dev);
 969         mutex_unlock(&nvmem_mutex);
 970         if (!nvmem)
 971                 return ERR_PTR(-EPROBE_DEFER);
 972
 973         if (!try_module_get(nvmem->owner)) {
 974                 dev_err(&nvmem->dev,
 975                         "could not increase module refcount for cell %s\n",
 976                         nvmem_dev_name(nvmem));
 977
 978                 put_device(&nvmem->dev);
 979                 return ERR_PTR(-EINVAL);
 980         }
 981
 982         kref_get(&nvmem->refcnt);
 983
 984         return nvmem;
 985 }
 986
 987 static void __nvmem_device_put(struct nvmem_device *nvmem)
 988 {
 989         put_device(&nvmem->dev);
 990         module_put(nvmem->owner);
 991         kref_put(&nvmem->refcnt, nvmem_device_release);
 992 }
 993
 994 #if IS_ENABLED(CONFIG_OF)
 995 /**
 996  * of_nvmem_device_get() - Get nvmem device from a given id
 997  *
 998  * @np: Device tree node that uses the nvmem device.
 999  * @id: nvmem name from nvmem-names property.
1000  *
1001  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1002  * on success.
1003  */
1004 struct nvmem_device *of_nvmem_device_get(struct device_node *np, const char *id)
1005 {
1006
1007         struct device_node *nvmem_np;
1008         struct nvmem_device *nvmem;
1009         int index = 0;
1010
1011         if (id)
1012                 index = of_property_match_string(np, "nvmem-names", id);
1013
1014         nvmem_np = of_parse_phandle(np, "nvmem", index);
1015         if (!nvmem_np)
1016                 return ERR_PTR(-ENOENT);
1017
1018         nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
1019         of_node_put(nvmem_np);
1020         return nvmem;
1021 }
1022 EXPORT_SYMBOL_GPL(of_nvmem_device_get);
1023 #endif
1024
1025 /**
1026  * nvmem_device_get() - Get nvmem device from a given id
1027  *
1028  * @dev: Device that uses the nvmem device.
1029  * @dev_name: name of the requested nvmem device.
1030  *
1031  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1032  * on success.
1033  */
1034 struct nvmem_device *nvmem_device_get(struct device *dev, const char *dev_name)
1035 {
1036         if (dev->of_node) { /* try dt first */
1037                 struct nvmem_device *nvmem;
1038
1039                 nvmem = of_nvmem_device_get(dev->of_node, dev_name);
1040
1041                 if (!IS_ERR(nvmem) || PTR_ERR(nvmem) == -EPROBE_DEFER)
1042                         return nvmem;
1043
1044         }
1045
1046         return __nvmem_device_get((void *)dev_name, device_match_name);
1047 }
1048 EXPORT_SYMBOL_GPL(nvmem_device_get);
1049
1050 /**
1051  * nvmem_device_find() - Find nvmem device with matching function
1052  *
1053  * @data: Data to pass to match function
1054  * @match: Callback function to check device
1055  *
1056  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1057  * on success.
1058  */
1059 struct nvmem_device *nvmem_device_find(void *data,
1060                         int (*match)(struct device *dev, const void *data))
1061 {
1062         return __nvmem_device_get(data, match);
1063 }
1064 EXPORT_SYMBOL_GPL(nvmem_device_find);
1065
1066 static int devm_nvmem_device_match(struct device *dev, void *res, void *data)
1067 {
1068         struct nvmem_device **nvmem = res;
1069
1070         if (WARN_ON(!nvmem || !*nvmem))
1071                 return 0;
1072
1073         return *nvmem == data;
1074 }
1075
1076 static void devm_nvmem_device_release(struct device *dev, void *res)
1077 {
1078         nvmem_device_put(*(struct nvmem_device **)res);
1079 }
1080
1081 /**
1082  * devm_nvmem_device_put() - put alredy got nvmem device
1083  *
1084  * @dev: Device that uses the nvmem device.
1085  * @nvmem: pointer to nvmem device allocated by devm_nvmem_cell_get(),
1086  * that needs to be released.
1087  */
1088 void devm_nvmem_device_put(struct device *dev, struct nvmem_device *nvmem)
1089 {
1090         int ret;
1091
1092         ret = devres_release(dev, devm_nvmem_device_release,
1093                              devm_nvmem_device_match, nvmem);
1094
1095         WARN_ON(ret);
1096 }
1097 EXPORT_SYMBOL_GPL(devm_nvmem_device_put);
1098
1099 /**
1100  * nvmem_device_put() - put alredy got nvmem device
1101  *
1102  * @nvmem: pointer to nvmem device that needs to be released.
1103  */
1104 void nvmem_device_put(struct nvmem_device *nvmem)
1105 {
1106         __nvmem_device_put(nvmem);
1107 }
1108 EXPORT_SYMBOL_GPL(nvmem_device_put);
1109
1110 /**
1111  * devm_nvmem_device_get() - Get nvmem cell of device form a given id
1112  *
1113  * @dev: Device that requests the nvmem device.
1114  * @id: name id for the requested nvmem device.
1115  *
1116  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_cell
1117  * on success.  The nvmem_cell will be freed by the automatically once the
1118  * device is freed.
1119  */
1120 struct nvmem_device *devm_nvmem_device_get(struct device *dev, const char *id)
1121 {
1122         struct nvmem_device **ptr, *nvmem;
1123
1124         ptr = devres_alloc(devm_nvmem_device_release, sizeof(*ptr), GFP_KERNEL);
1125         if (!ptr)
1126                 return ERR_PTR(-ENOMEM);
1127
1128         nvmem = nvmem_device_get(dev, id);
1129         if (!IS_ERR(nvmem)) {
1130                 *ptr = nvmem;
1131                 devres_add(dev, ptr);
1132         } else {
1133                 devres_free(ptr);
1134         }
1135
1136         return nvmem;
1137 }
1138 EXPORT_SYMBOL_GPL(devm_nvmem_device_get);
1139
1140 static struct nvmem_cell *
1141 nvmem_cell_get_from_lookup(struct device *dev, const char *con_id)
1142 {
1143         struct nvmem_cell *cell = ERR_PTR(-ENOENT);
1144         struct nvmem_cell_lookup *lookup;
1145         struct nvmem_device *nvmem;
1146         const char *dev_id;
1147
1148         if (!dev)
1149                 return ERR_PTR(-EINVAL);
1150
1151         dev_id = dev_name(dev);
1152
1153         mutex_lock(&nvmem_lookup_mutex);
1154
1155         list_for_each_entry(lookup, &nvmem_lookup_list, node) {
1156                 if ((strcmp(lookup->dev_id, dev_id) == 0) &&
1157                     (strcmp(lookup->con_id, con_id) == 0)) {
1158                         /* This is the right entry. */
1159                         nvmem = __nvmem_device_get((void *)lookup->nvmem_name,
1160                                                    device_match_name);
1161                         if (IS_ERR(nvmem)) {
1162                                 /* Provider may not be registered yet. */
1163                                 cell = ERR_CAST(nvmem);
1164                                 break;
1165                         }
1166
1167                         cell = nvmem_find_cell_by_name(nvmem,
1168                                                        lookup->cell_name);
1169                         if (!cell) {
1170                                 __nvmem_device_put(nvmem);
1171                                 cell = ERR_PTR(-ENOENT);
1172                         }
1173                         break;
1174                 }
1175         }
1176
1177         mutex_unlock(&nvmem_lookup_mutex);
1178         return cell;
1179 }
1180
1181 #if IS_ENABLED(CONFIG_OF)
1182 static struct nvmem_cell *
1183 nvmem_find_cell_by_node(struct nvmem_device *nvmem, struct device_node *np)
1184 {
1185         struct nvmem_cell *iter, *cell = NULL;
1186
1187         mutex_lock(&nvmem_mutex);
1188         list_for_each_entry(iter, &nvmem->cells, node) {
1189                 if (np == iter->np) {
1190                         cell = iter;
1191                         break;
1192                 }
1193         }
1194         mutex_unlock(&nvmem_mutex);
1195
1196         return cell;
1197 }
1198
1199 /**
1200  * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
1201  *
1202  * @np: Device tree node that uses the nvmem cell.
1203  * @id: nvmem cell name from nvmem-cell-names property, or NULL
1204  *      for the cell at index 0 (the lone cell with no accompanying
1205  *      nvmem-cell-names property).
1206  *
1207  * Return: Will be an ERR_PTR() on error or a valid pointer
1208  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1209  * nvmem_cell_put().
1210  */
1211 struct nvmem_cell *of_nvmem_cell_get(struct device_node *np, const char *id)
1212 {
1213         struct device_node *cell_np, *nvmem_np;
1214         struct nvmem_device *nvmem;
1215         struct nvmem_cell *cell;
1216         int index = 0;
1217
1218         /* if cell name exists, find index to the name */
1219         if (id)
1220                 index = of_property_match_string(np, "nvmem-cell-names", id);
1221
1222         cell_np = of_parse_phandle(np, "nvmem-cells", index);
1223         if (!cell_np)
1224                 return ERR_PTR(-ENOENT);
1225
1226         nvmem_np = of_get_next_parent(cell_np);
1227         if (!nvmem_np)
1228                 return ERR_PTR(-EINVAL);
1229
1230         nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
1231         of_node_put(nvmem_np);
1232         if (IS_ERR(nvmem))
1233                 return ERR_CAST(nvmem);
1234
1235         cell = nvmem_find_cell_by_node(nvmem, cell_np);
1236         if (!cell) {
1237                 __nvmem_device_put(nvmem);
1238                 return ERR_PTR(-ENOENT);
1239         }
1240
1241         return cell;
1242 }
1243 EXPORT_SYMBOL_GPL(of_nvmem_cell_get);
1244 #endif
1245
1246 /**
1247  * nvmem_cell_get() - Get nvmem cell of device form a given cell name
1248  *
1249  * @dev: Device that requests the nvmem cell.
1250  * @id: nvmem cell name to get (this corresponds with the name from the
1251  *      nvmem-cell-names property for DT systems and with the con_id from
1252  *      the lookup entry for non-DT systems).
1253  *
1254  * Return: Will be an ERR_PTR() on error or a valid pointer
1255  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1256  * nvmem_cell_put().
1257  */
1258 struct nvmem_cell *nvmem_cell_get(struct device *dev, const char *id)
1259 {
1260         struct nvmem_cell *cell;
1261
1262         if (dev->of_node) { /* try dt first */
1263                 cell = of_nvmem_cell_get(dev->of_node, id);
1264                 if (!IS_ERR(cell) || PTR_ERR(cell) == -EPROBE_DEFER)
1265                         return cell;
1266         }
1267
1268         /* NULL cell id only allowed for device tree; invalid otherwise */
1269         if (!id)
1270                 return ERR_PTR(-EINVAL);
1271
1272         return nvmem_cell_get_from_lookup(dev, id);
1273 }
1274 EXPORT_SYMBOL_GPL(nvmem_cell_get);
1275
1276 static void devm_nvmem_cell_release(struct device *dev, void *res)
1277 {
1278         nvmem_cell_put(*(struct nvmem_cell **)res);
1279 }
1280
1281 /**
1282  * devm_nvmem_cell_get() - Get nvmem cell of device form a given id
1283  *
1284  * @dev: Device that requests the nvmem cell.
1285  * @id: nvmem cell name id to get.
1286  *
1287  * Return: Will be an ERR_PTR() on error or a valid pointer
1288  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1289  * automatically once the device is freed.
1290  */
1291 struct nvmem_cell *devm_nvmem_cell_get(struct device *dev, const char *id)
1292 {
1293         struct nvmem_cell **ptr, *cell;
1294
1295         ptr = devres_alloc(devm_nvmem_cell_release, sizeof(*ptr), GFP_KERNEL);
1296         if (!ptr)
1297                 return ERR_PTR(-ENOMEM);
1298
1299         cell = nvmem_cell_get(dev, id);
1300         if (!IS_ERR(cell)) {
1301                 *ptr = cell;
1302                 devres_add(dev, ptr);
1303         } else {
1304                 devres_free(ptr);
1305         }
1306
1307         return cell;
1308 }
1309 EXPORT_SYMBOL_GPL(devm_nvmem_cell_get);
1310
1311 static int devm_nvmem_cell_match(struct device *dev, void *res, void *data)
1312 {
1313         struct nvmem_cell **c = res;
1314
1315         if (WARN_ON(!c || !*c))
1316                 return 0;
1317
1318         return *c == data;
1319 }
1320
1321 /**
1322  * devm_nvmem_cell_put() - Release previously allocated nvmem cell
1323  * from devm_nvmem_cell_get.
1324  *
1325  * @dev: Device that requests the nvmem cell.
1326  * @cell: Previously allocated nvmem cell by devm_nvmem_cell_get().
1327  */
1328 void devm_nvmem_cell_put(struct device *dev, struct nvmem_cell *cell)
1329 {
1330         int ret;
1331
1332         ret = devres_release(dev, devm_nvmem_cell_release,
1333                                 devm_nvmem_cell_match, cell);
1334
1335         WARN_ON(ret);
1336 }
1337 EXPORT_SYMBOL(devm_nvmem_cell_put);
1338
1339 /**
1340  * nvmem_cell_put() - Release previously allocated nvmem cell.
1341  *
1342  * @cell: Previously allocated nvmem cell by nvmem_cell_get().
1343  */
1344 void nvmem_cell_put(struct nvmem_cell *cell)
1345 {
1346         struct nvmem_device *nvmem = cell->nvmem;
1347
1348         __nvmem_device_put(nvmem);
1349 }
1350 EXPORT_SYMBOL_GPL(nvmem_cell_put);
1351
1352 static void nvmem_shift_read_buffer_in_place(struct nvmem_cell *cell, void *buf)
1353 {
1354         u8 *p, *b;
1355         int i, extra, bit_offset = cell->bit_offset;
1356
1357         p = b = buf;
1358         if (bit_offset) {
1359                 /* First shift */
1360                 *b++ >>= bit_offset;
1361
1362                 /* setup rest of the bytes if any */
1363                 for (i = 1; i < cell->bytes; i++) {
1364                         /* Get bits from next byte and shift them towards msb */
1365                         *p |= *b << (BITS_PER_BYTE - bit_offset);
1366
1367                         p = b;
1368                         *b++ >>= bit_offset;
1369                 }
1370         } else {
1371                 /* point to the msb */
1372                 p += cell->bytes - 1;
1373         }
1374
1375         /* result fits in less bytes */
1376         extra = cell->bytes - DIV_ROUND_UP(cell->nbits, BITS_PER_BYTE);
1377         while (--extra >= 0)
1378                 *p-- = 0;
1379
1380         /* clear msb bits if any leftover in the last byte */
1381         *p &= GENMASK((cell->nbits%BITS_PER_BYTE) - 1, 0);
1382 }
1383
1384 static int __nvmem_cell_read(struct nvmem_device *nvmem,
1385                       struct nvmem_cell *cell,
1386                       void *buf, size_t *len)
1387 {
1388         int rc;
1389
1390         rc = nvmem_reg_read(nvmem, cell->offset, buf, cell->bytes);
1391
1392         if (rc)
1393                 return rc;
1394
1395         /* shift bits in-place */
1396         if (cell->bit_offset || cell->nbits)
1397                 nvmem_shift_read_buffer_in_place(cell, buf);
1398
1399         if (len)
1400                 *len = cell->bytes;
1401
1402         return 0;
1403 }
1404
1405 /**
1406  * nvmem_cell_read() - Read a given nvmem cell
1407  *
1408  * @cell: nvmem cell to be read.
1409  * @len: pointer to length of cell which will be populated on successful read;
1410  *       can be NULL.
1411  *
1412  * Return: ERR_PTR() on error or a valid pointer to a buffer on success. The
1413  * buffer should be freed by the consumer with a kfree().
1414  */
1415 void *nvmem_cell_read(struct nvmem_cell *cell, size_t *len)
1416 {
1417         struct nvmem_device *nvmem = cell->nvmem;
1418         u8 *buf;
1419         int rc;
1420
1421         if (!nvmem)
1422                 return ERR_PTR(-EINVAL);
1423
1424         buf = kzalloc(cell->bytes, GFP_KERNEL);
1425         if (!buf)
1426                 return ERR_PTR(-ENOMEM);
1427
1428         rc = __nvmem_cell_read(nvmem, cell, buf, len);
1429         if (rc) {
1430                 kfree(buf);
1431                 return ERR_PTR(rc);
1432         }
1433
1434         return buf;
1435 }
1436 EXPORT_SYMBOL_GPL(nvmem_cell_read);
1437
1438 static void *nvmem_cell_prepare_write_buffer(struct nvmem_cell *cell,
1439                                              u8 *_buf, int len)
1440 {
1441         struct nvmem_device *nvmem = cell->nvmem;
1442         int i, rc, nbits, bit_offset = cell->bit_offset;
1443         u8 v, *p, *buf, *b, pbyte, pbits;
1444
1445         nbits = cell->nbits;
1446         buf = kzalloc(cell->bytes, GFP_KERNEL);
1447         if (!buf)
1448                 return ERR_PTR(-ENOMEM);
1449
1450         memcpy(buf, _buf, len);
1451         p = b = buf;
1452
1453         if (bit_offset) {
1454                 pbyte = *b;
1455                 *b <<= bit_offset;
1456
1457                 /* setup the first byte with lsb bits from nvmem */
1458                 rc = nvmem_reg_read(nvmem, cell->offset, &v, 1);
1459                 if (rc)
1460                         goto err;
1461                 *b++ |= GENMASK(bit_offset - 1, 0) & v;
1462
1463                 /* setup rest of the byte if any */
1464                 for (i = 1; i < cell->bytes; i++) {
1465                         /* Get last byte bits and shift them towards lsb */
1466                         pbits = pbyte >> (BITS_PER_BYTE - 1 - bit_offset);
1467                         pbyte = *b;
1468                         p = b;
1469                         *b <<= bit_offset;
1470                         *b++ |= pbits;
1471                 }
1472         }
1473
1474         /* if it's not end on byte boundary */
1475         if ((nbits + bit_offset) % BITS_PER_BYTE) {
1476                 /* setup the last byte with msb bits from nvmem */
1477                 rc = nvmem_reg_read(nvmem,
1478                                     cell->offset + cell->bytes - 1, &v, 1);
1479                 if (rc)
1480                         goto err;
1481                 *p |= GENMASK(7, (nbits + bit_offset) % BITS_PER_BYTE) & v;
1482
1483         }
1484
1485         return buf;
1486 err:
1487         kfree(buf);
1488         return ERR_PTR(rc);
1489 }
1490
1491 /**
1492  * nvmem_cell_write() - Write to a given nvmem cell
1493  *
1494  * @cell: nvmem cell to be written.
1495  * @buf: Buffer to be written.
1496  * @len: length of buffer to be written to nvmem cell.
1497  *
1498  * Return: length of bytes written or negative on failure.
1499  */
1500 int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len)
1501 {
1502         struct nvmem_device *nvmem = cell->nvmem;
1503         int rc;
1504
1505         if (!nvmem || nvmem->read_only ||
1506             (cell->bit_offset == 0 && len != cell->bytes))
1507                 return -EINVAL;
1508
1509         if (cell->bit_offset || cell->nbits) {
1510                 buf = nvmem_cell_prepare_write_buffer(cell, buf, len);
1511                 if (IS_ERR(buf))
1512                         return PTR_ERR(buf);
1513         }
1514
1515         rc = nvmem_reg_write(nvmem, cell->offset, buf, cell->bytes);
1516
1517         /* free the tmp buffer */
1518         if (cell->bit_offset || cell->nbits)
1519                 kfree(buf);
1520
1521         if (rc)
1522                 return rc;
1523
1524         return len;
1525 }
1526 EXPORT_SYMBOL_GPL(nvmem_cell_write);
1527
1528 static int nvmem_cell_read_common(struct device *dev, const char *cell_id,
1529                                   void *val, size_t count)
1530 {
1531         struct nvmem_cell *cell;
1532         void *buf;
1533         size_t len;
1534
1535         cell = nvmem_cell_get(dev, cell_id);
1536         if (IS_ERR(cell))
1537                 return PTR_ERR(cell);
1538
1539         buf = nvmem_cell_read(cell, &len);
1540         if (IS_ERR(buf)) {
1541                 nvmem_cell_put(cell);
1542                 return PTR_ERR(buf);
1543         }
1544         if (len != count) {
1545                 kfree(buf);
1546                 nvmem_cell_put(cell);
1547                 return -EINVAL;
1548         }
1549         memcpy(val, buf, count);
1550         kfree(buf);
1551         nvmem_cell_put(cell);
1552
1553         return 0;
1554 }
1555
1556 /**
1557  * nvmem_cell_read_u8() - Read a cell value as a u8
1558  *
1559  * @dev: Device that requests the nvmem cell.
1560  * @cell_id: Name of nvmem cell to read.
1561  * @val: pointer to output value.
1562  *
1563  * Return: 0 on success or negative errno.
1564  */
1565 int nvmem_cell_read_u8(struct device *dev, const char *cell_id, u8 *val)
1566 {
1567         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1568 }
1569 EXPORT_SYMBOL_GPL(nvmem_cell_read_u8);
1570
1571 /**
1572  * nvmem_cell_read_u16() - Read a cell value as a u16
1573  *
1574  * @dev: Device that requests the nvmem cell.
1575  * @cell_id: Name of nvmem cell to read.
1576  * @val: pointer to output value.
1577  *
1578  * Return: 0 on success or negative errno.
1579  */
1580 int nvmem_cell_read_u16(struct device *dev, const char *cell_id, u16 *val)
1581 {
1582         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1583 }
1584 EXPORT_SYMBOL_GPL(nvmem_cell_read_u16);
1585
1586 /**
1587  * nvmem_cell_read_u32() - Read a cell value as a u32
1588  *
1589  * @dev: Device that requests the nvmem cell.
1590  * @cell_id: Name of nvmem cell to read.
1591  * @val: pointer to output value.
1592  *
1593  * Return: 0 on success or negative errno.
1594  */
1595 int nvmem_cell_read_u32(struct device *dev, const char *cell_id, u32 *val)
1596 {
1597         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1598 }
1599 EXPORT_SYMBOL_GPL(nvmem_cell_read_u32);
1600
1601 /**
1602  * nvmem_cell_read_u64() - Read a cell value as a u64
1603  *
1604  * @dev: Device that requests the nvmem cell.
1605  * @cell_id: Name of nvmem cell to read.
1606  * @val: pointer to output value.
1607  *
1608  * Return: 0 on success or negative errno.
1609  */
1610 int nvmem_cell_read_u64(struct device *dev, const char *cell_id, u64 *val)
1611 {
1612         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1613 }
1614 EXPORT_SYMBOL_GPL(nvmem_cell_read_u64);
1615
1616 static const void *nvmem_cell_read_variable_common(struct device *dev,
1617                                                    const char *cell_id,
1618                                                    size_t max_len, size_t *len)
1619 {
1620         struct nvmem_cell *cell;
1621         int nbits;
1622         void *buf;
1623
1624         cell = nvmem_cell_get(dev, cell_id);
1625         if (IS_ERR(cell))
1626                 return cell;
1627
1628         nbits = cell->nbits;
1629         buf = nvmem_cell_read(cell, len);
1630         nvmem_cell_put(cell);
1631         if (IS_ERR(buf))
1632                 return buf;
1633
1634         /*
1635          * If nbits is set then nvmem_cell_read() can significantly exaggerate
1636          * the length of the real data. Throw away the extra junk.
1637          */
1638         if (nbits)
1639                 *len = DIV_ROUND_UP(nbits, 8);
1640
1641         if (*len > max_len) {
1642                 kfree(buf);
1643                 return ERR_PTR(-ERANGE);
1644         }
1645
1646         return buf;
1647 }
1648
1649 /**
1650  * nvmem_cell_read_variable_le_u32() - Read up to 32-bits of data as a little endian number.
1651  *
1652  * @dev: Device that requests the nvmem cell.
1653  * @cell_id: Name of nvmem cell to read.
1654  * @val: pointer to output value.
1655  *
1656  * Return: 0 on success or negative errno.
1657  */
1658 int nvmem_cell_read_variable_le_u32(struct device *dev, const char *cell_id,
1659                                     u32 *val)
1660 {
1661         size_t len;
1662         const u8 *buf;
1663         int i;
1664
1665         buf = nvmem_cell_read_variable_common(dev, cell_id, sizeof(*val), &len);
1666         if (IS_ERR(buf))
1667                 return PTR_ERR(buf);
1668
1669         /* Copy w/ implicit endian conversion */
1670         *val = 0;
1671         for (i = 0; i < len; i++)
1672                 *val |= buf[i] << (8 * i);
1673
1674         kfree(buf);
1675
1676         return 0;
1677 }
1678 EXPORT_SYMBOL_GPL(nvmem_cell_read_variable_le_u32);
1679
1680 /**
1681  * nvmem_cell_read_variable_le_u64() - Read up to 64-bits of data as a little endian number.
1682  *
1683  * @dev: Device that requests the nvmem cell.
1684  * @cell_id: Name of nvmem cell to read.
1685  * @val: pointer to output value.
1686  *
1687  * Return: 0 on success or negative errno.
1688  */
1689 int nvmem_cell_read_variable_le_u64(struct device *dev, const char *cell_id,
1690                                     u64 *val)
1691 {
1692         size_t len;
1693         const u8 *buf;
1694         int i;
1695
1696         buf = nvmem_cell_read_variable_common(dev, cell_id, sizeof(*val), &len);
1697         if (IS_ERR(buf))
1698                 return PTR_ERR(buf);
1699
1700         /* Copy w/ implicit endian conversion */
1701         *val = 0;
1702         for (i = 0; i < len; i++)
1703                 *val |= (uint64_t)buf[i] << (8 * i);
1704
1705         kfree(buf);
1706
1707         return 0;
1708 }
1709 EXPORT_SYMBOL_GPL(nvmem_cell_read_variable_le_u64);
1710
1711 /**
1712  * nvmem_device_cell_read() - Read a given nvmem device and cell
1713  *
1714  * @nvmem: nvmem device to read from.
1715  * @info: nvmem cell info to be read.
1716  * @buf: buffer pointer which will be populated on successful read.
1717  *
1718  * Return: length of successful bytes read on success and negative
1719  * error code on error.
1720  */
1721 ssize_t nvmem_device_cell_read(struct nvmem_device *nvmem,
1722                            struct nvmem_cell_info *info, void *buf)
1723 {
1724         struct nvmem_cell cell;
1725         int rc;
1726         ssize_t len;
1727
1728         if (!nvmem)
1729                 return -EINVAL;
1730
1731         rc = nvmem_cell_info_to_nvmem_cell_nodup(nvmem, info, &cell);
1732         if (rc)
1733                 return rc;
1734
1735         rc = __nvmem_cell_read(nvmem, &cell, buf, &len);
1736         if (rc)
1737                 return rc;
1738
1739         return len;
1740 }
1741 EXPORT_SYMBOL_GPL(nvmem_device_cell_read);
1742
1743 /**
1744  * nvmem_device_cell_write() - Write cell to a given nvmem device
1745  *
1746  * @nvmem: nvmem device to be written to.
1747  * @info: nvmem cell info to be written.
1748  * @buf: buffer to be written to cell.
1749  *
1750  * Return: length of bytes written or negative error code on failure.
1751  */
1752 int nvmem_device_cell_write(struct nvmem_device *nvmem,
1753                             struct nvmem_cell_info *info, void *buf)
1754 {
1755         struct nvmem_cell cell;
1756         int rc;
1757
1758         if (!nvmem)
1759                 return -EINVAL;
1760
1761         rc = nvmem_cell_info_to_nvmem_cell_nodup(nvmem, info, &cell);
1762         if (rc)
1763                 return rc;
1764
1765         return nvmem_cell_write(&cell, buf, cell.bytes);
1766 }
1767 EXPORT_SYMBOL_GPL(nvmem_device_cell_write);
1768
1769 /**
1770  * nvmem_device_read() - Read from a given nvmem device
1771  *
1772  * @nvmem: nvmem device to read from.
1773  * @offset: offset in nvmem device.
1774  * @bytes: number of bytes to read.
1775  * @buf: buffer pointer which will be populated on successful read.
1776  *
1777  * Return: length of successful bytes read on success and negative
1778  * error code on error.
1779  */
1780 int nvmem_device_read(struct nvmem_device *nvmem,
1781                       unsigned int offset,
1782                       size_t bytes, void *buf)
1783 {
1784         int rc;
1785
1786         if (!nvmem)
1787                 return -EINVAL;
1788
1789         rc = nvmem_reg_read(nvmem, offset, buf, bytes);
1790
1791         if (rc)
1792                 return rc;
1793
1794         return bytes;
1795 }
1796 EXPORT_SYMBOL_GPL(nvmem_device_read);
1797
1798 /**
1799  * nvmem_device_write() - Write cell to a given nvmem device
1800  *
1801  * @nvmem: nvmem device to be written to.
1802  * @offset: offset in nvmem device.
1803  * @bytes: number of bytes to write.
1804  * @buf: buffer to be written.
1805  *
1806  * Return: length of bytes written or negative error code on failure.
1807  */
1808 int nvmem_device_write(struct nvmem_device *nvmem,
1809                        unsigned int offset,
1810                        size_t bytes, void *buf)
1811 {
1812         int rc;
1813
1814         if (!nvmem)
1815                 return -EINVAL;
1816
1817         rc = nvmem_reg_write(nvmem, offset, buf, bytes);
1818
1819         if (rc)
1820                 return rc;
1821
1822
1823         return bytes;
1824 }
1825 EXPORT_SYMBOL_GPL(nvmem_device_write);
1826
1827 /**
1828  * nvmem_add_cell_table() - register a table of cell info entries
1829  *
1830  * @table: table of cell info entries
1831  */
1832 void nvmem_add_cell_table(struct nvmem_cell_table *table)
1833 {
1834         mutex_lock(&nvmem_cell_mutex);
1835         list_add_tail(&table->node, &nvmem_cell_tables);
1836         mutex_unlock(&nvmem_cell_mutex);
1837 }
1838 EXPORT_SYMBOL_GPL(nvmem_add_cell_table);
1839
1840 /**
1841  * nvmem_del_cell_table() - remove a previously registered cell info table
1842  *
1843  * @table: table of cell info entries
1844  */
1845 void nvmem_del_cell_table(struct nvmem_cell_table *table)
1846 {
1847         mutex_lock(&nvmem_cell_mutex);
1848         list_del(&table->node);
1849         mutex_unlock(&nvmem_cell_mutex);
1850 }
1851 EXPORT_SYMBOL_GPL(nvmem_del_cell_table);
1852
1853 /**
1854  * nvmem_add_cell_lookups() - register a list of cell lookup entries
1855  *
1856  * @entries: array of cell lookup entries
1857  * @nentries: number of cell lookup entries in the array
1858  */
1859 void nvmem_add_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
1860 {
1861         int i;
1862
1863         mutex_lock(&nvmem_lookup_mutex);
1864         for (i = 0; i < nentries; i++)
1865                 list_add_tail(&entries[i].node, &nvmem_lookup_list);
1866         mutex_unlock(&nvmem_lookup_mutex);
1867 }
1868 EXPORT_SYMBOL_GPL(nvmem_add_cell_lookups);
1869
1870 /**
1871  * nvmem_del_cell_lookups() - remove a list of previously added cell lookup
1872  *                            entries
1873  *
1874  * @entries: array of cell lookup entries
1875  * @nentries: number of cell lookup entries in the array
1876  */
1877 void nvmem_del_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
1878 {
1879         int i;
1880
1881         mutex_lock(&nvmem_lookup_mutex);
1882         for (i = 0; i < nentries; i++)
1883                 list_del(&entries[i].node);
1884         mutex_unlock(&nvmem_lookup_mutex);
1885 }
1886 EXPORT_SYMBOL_GPL(nvmem_del_cell_lookups);
1887
1888 /**
1889  * nvmem_dev_name() - Get the name of a given nvmem device.
1890  *
1891  * @nvmem: nvmem device.
1892  *
1893  * Return: name of the nvmem device.
1894  */
1895 const char *nvmem_dev_name(struct nvmem_device *nvmem)
1896 {
1897         return dev_name(&nvmem->dev);
1898 }
1899 EXPORT_SYMBOL_GPL(nvmem_dev_name);
1900
1901 static int __init nvmem_init(void)
1902 {
1903         return bus_register(&nvmem_bus_type);
1904 }
1905
1906 static void __exit nvmem_exit(void)
1907 {
1908         bus_unregister(&nvmem_bus_type);
1909 }
1910
1911 subsys_initcall(nvmem_init);
1912 module_exit(nvmem_exit);
1913
1914 MODULE_AUTHOR("Srinivas Kandagatla <srinivas.kandagatla@linaro.org");
1915 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com");
1916 MODULE_DESCRIPTION("nvmem Driver Core");
1917 MODULE_LICENSE("GPL v2");