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         nvmem_cell_post_process_t cell_post_process;
  42         struct gpio_desc        *wp_gpio;
  43         void *priv;
  44 };
  45
  46 #define to_nvmem_device(d) container_of(d, struct nvmem_device, dev)
  47
  48 #define FLAG_COMPAT             BIT(0)
  49 struct nvmem_cell_entry {
  50         const char              *name;
  51         int                     offset;
  52         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 struct nvmem_cell {
  61         struct nvmem_cell_entry *entry;
  62         const char              *id;
  63         int                     index;
  64 };
  65
  66 static DEFINE_MUTEX(nvmem_mutex);
  67 static DEFINE_IDA(nvmem_ida);
  68
  69 static DEFINE_MUTEX(nvmem_cell_mutex);
  70 static LIST_HEAD(nvmem_cell_tables);
  71
  72 static DEFINE_MUTEX(nvmem_lookup_mutex);
  73 static LIST_HEAD(nvmem_lookup_list);
  74
  75 static BLOCKING_NOTIFIER_HEAD(nvmem_notifier);
  76
  77 static int __nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
  78                             void *val, size_t bytes)
  79 {
  80         if (nvmem->reg_read)
  81                 return nvmem->reg_read(nvmem->priv, offset, val, bytes);
  82
  83         return -EINVAL;
  84 }
  85
  86 static int __nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
  87                              void *val, size_t bytes)
  88 {
  89         int ret;
  90
  91         if (nvmem->reg_write) {
  92                 gpiod_set_value_cansleep(nvmem->wp_gpio, 0);
  93                 ret = nvmem->reg_write(nvmem->priv, offset, val, bytes);
  94                 gpiod_set_value_cansleep(nvmem->wp_gpio, 1);
  95                 return ret;
  96         }
  97
  98         return -EINVAL;
  99 }
 100
 101 static int nvmem_access_with_keepouts(struct nvmem_device *nvmem,
 102                                       unsigned int offset, void *val,
 103                                       size_t bytes, int write)
 104 {
 105
 106         unsigned int end = offset + bytes;
 107         unsigned int kend, ksize;
 108         const struct nvmem_keepout *keepout = nvmem->keepout;
 109         const struct nvmem_keepout *keepoutend = keepout + nvmem->nkeepout;
 110         int rc;
 111
 112         /*
 113          * Skip all keepouts before the range being accessed.
 114          * Keepouts are sorted.
 115          */
 116         while ((keepout < keepoutend) && (keepout->end <= offset))
 117                 keepout++;
 118
 119         while ((offset < end) && (keepout < keepoutend)) {
 120                 /* Access the valid portion before the keepout. */
 121                 if (offset < keepout->start) {
 122                         kend = min(end, keepout->start);
 123                         ksize = kend - offset;
 124                         if (write)
 125                                 rc = __nvmem_reg_write(nvmem, offset, val, ksize);
 126                         else
 127                                 rc = __nvmem_reg_read(nvmem, offset, val, ksize);
 128
 129                         if (rc)
 130                                 return rc;
 131
 132                         offset += ksize;
 133                         val += ksize;
 134                 }
 135
 136                 /*
 137                  * Now we're aligned to the start of this keepout zone. Go
 138                  * through it.
 139                  */
 140                 kend = min(end, keepout->end);
 141                 ksize = kend - offset;
 142                 if (!write)
 143                         memset(val, keepout->value, ksize);
 144
 145                 val += ksize;
 146                 offset += ksize;
 147                 keepout++;
 148         }
 149
 150         /*
 151          * If we ran out of keepouts but there's still stuff to do, send it
 152          * down directly
 153          */
 154         if (offset < end) {
 155                 ksize = end - offset;
 156                 if (write)
 157                         return __nvmem_reg_write(nvmem, offset, val, ksize);
 158                 else
 159                         return __nvmem_reg_read(nvmem, offset, val, ksize);
 160         }
 161
 162         return 0;
 163 }
 164
 165 static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
 166                           void *val, size_t bytes)
 167 {
 168         if (!nvmem->nkeepout)
 169                 return __nvmem_reg_read(nvmem, offset, val, bytes);
 170
 171         return nvmem_access_with_keepouts(nvmem, offset, val, bytes, false);
 172 }
 173
 174 static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
 175                            void *val, size_t bytes)
 176 {
 177         if (!nvmem->nkeepout)
 178                 return __nvmem_reg_write(nvmem, offset, val, bytes);
 179
 180         return nvmem_access_with_keepouts(nvmem, offset, val, bytes, true);
 181 }
 182
 183 #ifdef CONFIG_NVMEM_SYSFS
 184 static const char * const nvmem_type_str[] = {
 185         [NVMEM_TYPE_UNKNOWN] = "Unknown",
 186         [NVMEM_TYPE_EEPROM] = "EEPROM",
 187         [NVMEM_TYPE_OTP] = "OTP",
 188         [NVMEM_TYPE_BATTERY_BACKED] = "Battery backed",
 189         [NVMEM_TYPE_FRAM] = "FRAM",
 190 };
 191
 192 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 193 static struct lock_class_key eeprom_lock_key;
 194 #endif
 195
 196 static ssize_t type_show(struct device *dev,
 197                          struct device_attribute *attr, char *buf)
 198 {
 199         struct nvmem_device *nvmem = to_nvmem_device(dev);
 200
 201         return sprintf(buf, "%s\n", nvmem_type_str[nvmem->type]);
 202 }
 203
 204 static DEVICE_ATTR_RO(type);
 205
 206 static struct attribute *nvmem_attrs[] = {
 207         &dev_attr_type.attr,
 208         NULL,
 209 };
 210
 211 static ssize_t bin_attr_nvmem_read(struct file *filp, struct kobject *kobj,
 212                                    struct bin_attribute *attr, char *buf,
 213                                    loff_t pos, size_t count)
 214 {
 215         struct device *dev;
 216         struct nvmem_device *nvmem;
 217         int rc;
 218
 219         if (attr->private)
 220                 dev = attr->private;
 221         else
 222                 dev = kobj_to_dev(kobj);
 223         nvmem = to_nvmem_device(dev);
 224
 225         /* Stop the user from reading */
 226         if (pos >= nvmem->size)
 227                 return 0;
 228
 229         if (!IS_ALIGNED(pos, nvmem->stride))
 230                 return -EINVAL;
 231
 232         if (count < nvmem->word_size)
 233                 return -EINVAL;
 234
 235         if (pos + count > nvmem->size)
 236                 count = nvmem->size - pos;
 237
 238         count = round_down(count, nvmem->word_size);
 239
 240         if (!nvmem->reg_read)
 241                 return -EPERM;
 242
 243         rc = nvmem_reg_read(nvmem, pos, buf, count);
 244
 245         if (rc)
 246                 return rc;
 247
 248         return count;
 249 }
 250
 251 static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj,
 252                                     struct bin_attribute *attr, char *buf,
 253                                     loff_t pos, size_t count)
 254 {
 255         struct device *dev;
 256         struct nvmem_device *nvmem;
 257         int rc;
 258
 259         if (attr->private)
 260                 dev = attr->private;
 261         else
 262                 dev = kobj_to_dev(kobj);
 263         nvmem = to_nvmem_device(dev);
 264
 265         /* Stop the user from writing */
 266         if (pos >= nvmem->size)
 267                 return -EFBIG;
 268
 269         if (!IS_ALIGNED(pos, nvmem->stride))
 270                 return -EINVAL;
 271
 272         if (count < nvmem->word_size)
 273                 return -EINVAL;
 274
 275         if (pos + count > nvmem->size)
 276                 count = nvmem->size - pos;
 277
 278         count = round_down(count, nvmem->word_size);
 279
 280         if (!nvmem->reg_write)
 281                 return -EPERM;
 282
 283         rc = nvmem_reg_write(nvmem, pos, buf, count);
 284
 285         if (rc)
 286                 return rc;
 287
 288         return count;
 289 }
 290
 291 static umode_t nvmem_bin_attr_get_umode(struct nvmem_device *nvmem)
 292 {
 293         umode_t mode = 0400;
 294
 295         if (!nvmem->root_only)
 296                 mode |= 0044;
 297
 298         if (!nvmem->read_only)
 299                 mode |= 0200;
 300
 301         if (!nvmem->reg_write)
 302                 mode &= ~0200;
 303
 304         if (!nvmem->reg_read)
 305                 mode &= ~0444;
 306
 307         return mode;
 308 }
 309
 310 static umode_t nvmem_bin_attr_is_visible(struct kobject *kobj,
 311                                          struct bin_attribute *attr, int i)
 312 {
 313         struct device *dev = kobj_to_dev(kobj);
 314         struct nvmem_device *nvmem = to_nvmem_device(dev);
 315
 316         attr->size = nvmem->size;
 317
 318         return nvmem_bin_attr_get_umode(nvmem);
 319 }
 320
 321 /* default read/write permissions */
 322 static struct bin_attribute bin_attr_rw_nvmem = {
 323         .attr   = {
 324                 .name   = "nvmem",
 325                 .mode   = 0644,
 326         },
 327         .read   = bin_attr_nvmem_read,
 328         .write  = bin_attr_nvmem_write,
 329 };
 330
 331 static struct bin_attribute *nvmem_bin_attributes[] = {
 332         &bin_attr_rw_nvmem,
 333         NULL,
 334 };
 335
 336 static const struct attribute_group nvmem_bin_group = {
 337         .bin_attrs      = nvmem_bin_attributes,
 338         .attrs          = nvmem_attrs,
 339         .is_bin_visible = nvmem_bin_attr_is_visible,
 340 };
 341
 342 static const struct attribute_group *nvmem_dev_groups[] = {
 343         &nvmem_bin_group,
 344         NULL,
 345 };
 346
 347 static struct bin_attribute bin_attr_nvmem_eeprom_compat = {
 348         .attr   = {
 349                 .name   = "eeprom",
 350         },
 351         .read   = bin_attr_nvmem_read,
 352         .write  = bin_attr_nvmem_write,
 353 };
 354
 355 /*
 356  * nvmem_setup_compat() - Create an additional binary entry in
 357  * drivers sys directory, to be backwards compatible with the older
 358  * drivers/misc/eeprom drivers.
 359  */
 360 static int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
 361                                     const struct nvmem_config *config)
 362 {
 363         int rval;
 364
 365         if (!config->compat)
 366                 return 0;
 367
 368         if (!config->base_dev)
 369                 return -EINVAL;
 370
 371         if (config->type == NVMEM_TYPE_FRAM)
 372                 bin_attr_nvmem_eeprom_compat.attr.name = "fram";
 373
 374         nvmem->eeprom = bin_attr_nvmem_eeprom_compat;
 375         nvmem->eeprom.attr.mode = nvmem_bin_attr_get_umode(nvmem);
 376         nvmem->eeprom.size = nvmem->size;
 377 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 378         nvmem->eeprom.attr.key = &eeprom_lock_key;
 379 #endif
 380         nvmem->eeprom.private = &nvmem->dev;
 381         nvmem->base_dev = config->base_dev;
 382
 383         rval = device_create_bin_file(nvmem->base_dev, &nvmem->eeprom);
 384         if (rval) {
 385                 dev_err(&nvmem->dev,
 386                         "Failed to create eeprom binary file %d\n", rval);
 387                 return rval;
 388         }
 389
 390         nvmem->flags |= FLAG_COMPAT;
 391
 392         return 0;
 393 }
 394
 395 static void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem,
 396                               const struct nvmem_config *config)
 397 {
 398         if (config->compat)
 399                 device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
 400 }
 401
 402 #else /* CONFIG_NVMEM_SYSFS */
 403
 404 static int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
 405                                     const struct nvmem_config *config)
 406 {
 407         return -ENOSYS;
 408 }
 409 static void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem,
 410                                       const struct nvmem_config *config)
 411 {
 412 }
 413
 414 #endif /* CONFIG_NVMEM_SYSFS */
 415
 416 static void nvmem_release(struct device *dev)
 417 {
 418         struct nvmem_device *nvmem = to_nvmem_device(dev);
 419
 420         ida_free(&nvmem_ida, nvmem->id);
 421         gpiod_put(nvmem->wp_gpio);
 422         kfree(nvmem);
 423 }
 424
 425 static const struct device_type nvmem_provider_type = {
 426         .release        = nvmem_release,
 427 };
 428
 429 static struct bus_type nvmem_bus_type = {
 430         .name           = "nvmem",
 431 };
 432
 433 static void nvmem_cell_entry_drop(struct nvmem_cell_entry *cell)
 434 {
 435         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_REMOVE, cell);
 436         mutex_lock(&nvmem_mutex);
 437         list_del(&cell->node);
 438         mutex_unlock(&nvmem_mutex);
 439         of_node_put(cell->np);
 440         kfree_const(cell->name);
 441         kfree(cell);
 442 }
 443
 444 static void nvmem_device_remove_all_cells(const struct nvmem_device *nvmem)
 445 {
 446         struct nvmem_cell_entry *cell, *p;
 447
 448         list_for_each_entry_safe(cell, p, &nvmem->cells, node)
 449                 nvmem_cell_entry_drop(cell);
 450 }
 451
 452 static void nvmem_cell_entry_add(struct nvmem_cell_entry *cell)
 453 {
 454         mutex_lock(&nvmem_mutex);
 455         list_add_tail(&cell->node, &cell->nvmem->cells);
 456         mutex_unlock(&nvmem_mutex);
 457         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_ADD, cell);
 458 }
 459
 460 static int nvmem_cell_info_to_nvmem_cell_entry_nodup(struct nvmem_device *nvmem,
 461                                                      const struct nvmem_cell_info *info,
 462                                                      struct nvmem_cell_entry *cell)
 463 {
 464         cell->nvmem = nvmem;
 465         cell->offset = info->offset;
 466         cell->bytes = info->bytes;
 467         cell->name = info->name;
 468
 469         cell->bit_offset = info->bit_offset;
 470         cell->nbits = info->nbits;
 471         cell->np = info->np;
 472
 473         if (cell->nbits)
 474                 cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
 475                                            BITS_PER_BYTE);
 476
 477         if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
 478                 dev_err(&nvmem->dev,
 479                         "cell %s unaligned to nvmem stride %d\n",
 480                         cell->name ?: "<unknown>", nvmem->stride);
 481                 return -EINVAL;
 482         }
 483
 484         return 0;
 485 }
 486
 487 static int nvmem_cell_info_to_nvmem_cell_entry(struct nvmem_device *nvmem,
 488                                                const struct nvmem_cell_info *info,
 489                                                struct nvmem_cell_entry *cell)
 490 {
 491         int err;
 492
 493         err = nvmem_cell_info_to_nvmem_cell_entry_nodup(nvmem, info, cell);
 494         if (err)
 495                 return err;
 496
 497         cell->name = kstrdup_const(info->name, GFP_KERNEL);
 498         if (!cell->name)
 499                 return -ENOMEM;
 500
 501         return 0;
 502 }
 503
 504 /**
 505  * nvmem_add_one_cell() - Add one cell information to an nvmem device
 506  *
 507  * @nvmem: nvmem device to add cells to.
 508  * @info: nvmem cell info to add to the device
 509  *
 510  * Return: 0 or negative error code on failure.
 511  */
 512 int nvmem_add_one_cell(struct nvmem_device *nvmem,
 513                        const struct nvmem_cell_info *info)
 514 {
 515         struct nvmem_cell_entry *cell;
 516         int rval;
 517
 518         cell = kzalloc(sizeof(*cell), GFP_KERNEL);
 519         if (!cell)
 520                 return -ENOMEM;
 521
 522         rval = nvmem_cell_info_to_nvmem_cell_entry(nvmem, info, cell);
 523         if (rval) {
 524                 kfree(cell);
 525                 return rval;
 526         }
 527
 528         nvmem_cell_entry_add(cell);
 529
 530         return 0;
 531 }
 532 EXPORT_SYMBOL_GPL(nvmem_add_one_cell);
 533
 534 /**
 535  * nvmem_add_cells() - Add cell information to an nvmem device
 536  *
 537  * @nvmem: nvmem device to add cells to.
 538  * @info: nvmem cell info to add to the device
 539  * @ncells: number of cells in info
 540  *
 541  * Return: 0 or negative error code on failure.
 542  */
 543 static int nvmem_add_cells(struct nvmem_device *nvmem,
 544                     const struct nvmem_cell_info *info,
 545                     int ncells)
 546 {
 547         int i, rval;
 548
 549         for (i = 0; i < ncells; i++) {
 550                 rval = nvmem_add_one_cell(nvmem, &info[i]);
 551                 if (rval)
 552                         return rval;
 553         }
 554
 555         return 0;
 556 }
 557
 558 /**
 559  * nvmem_register_notifier() - Register a notifier block for nvmem events.
 560  *
 561  * @nb: notifier block to be called on nvmem events.
 562  *
 563  * Return: 0 on success, negative error number on failure.
 564  */
 565 int nvmem_register_notifier(struct notifier_block *nb)
 566 {
 567         return blocking_notifier_chain_register(&nvmem_notifier, nb);
 568 }
 569 EXPORT_SYMBOL_GPL(nvmem_register_notifier);
 570
 571 /**
 572  * nvmem_unregister_notifier() - Unregister a notifier block for nvmem events.
 573  *
 574  * @nb: notifier block to be unregistered.
 575  *
 576  * Return: 0 on success, negative error number on failure.
 577  */
 578 int nvmem_unregister_notifier(struct notifier_block *nb)
 579 {
 580         return blocking_notifier_chain_unregister(&nvmem_notifier, nb);
 581 }
 582 EXPORT_SYMBOL_GPL(nvmem_unregister_notifier);
 583
 584 static int nvmem_add_cells_from_table(struct nvmem_device *nvmem)
 585 {
 586         const struct nvmem_cell_info *info;
 587         struct nvmem_cell_table *table;
 588         struct nvmem_cell_entry *cell;
 589         int rval = 0, i;
 590
 591         mutex_lock(&nvmem_cell_mutex);
 592         list_for_each_entry(table, &nvmem_cell_tables, node) {
 593                 if (strcmp(nvmem_dev_name(nvmem), table->nvmem_name) == 0) {
 594                         for (i = 0; i < table->ncells; i++) {
 595                                 info = &table->cells[i];
 596
 597                                 cell = kzalloc(sizeof(*cell), GFP_KERNEL);
 598                                 if (!cell) {
 599                                         rval = -ENOMEM;
 600                                         goto out;
 601                                 }
 602
 603                                 rval = nvmem_cell_info_to_nvmem_cell_entry(nvmem, info, cell);
 604                                 if (rval) {
 605                                         kfree(cell);
 606                                         goto out;
 607                                 }
 608
 609                                 nvmem_cell_entry_add(cell);
 610                         }
 611                 }
 612         }
 613
 614 out:
 615         mutex_unlock(&nvmem_cell_mutex);
 616         return rval;
 617 }
 618
 619 static struct nvmem_cell_entry *
 620 nvmem_find_cell_entry_by_name(struct nvmem_device *nvmem, const char *cell_id)
 621 {
 622         struct nvmem_cell_entry *iter, *cell = NULL;
 623
 624         mutex_lock(&nvmem_mutex);
 625         list_for_each_entry(iter, &nvmem->cells, node) {
 626                 if (strcmp(cell_id, iter->name) == 0) {
 627                         cell = iter;
 628                         break;
 629                 }
 630         }
 631         mutex_unlock(&nvmem_mutex);
 632
 633         return cell;
 634 }
 635
 636 static int nvmem_validate_keepouts(struct nvmem_device *nvmem)
 637 {
 638         unsigned int cur = 0;
 639         const struct nvmem_keepout *keepout = nvmem->keepout;
 640         const struct nvmem_keepout *keepoutend = keepout + nvmem->nkeepout;
 641
 642         while (keepout < keepoutend) {
 643                 /* Ensure keepouts are sorted and don't overlap. */
 644                 if (keepout->start < cur) {
 645                         dev_err(&nvmem->dev,
 646                                 "Keepout regions aren't sorted or overlap.\n");
 647
 648                         return -ERANGE;
 649                 }
 650
 651                 if (keepout->end < keepout->start) {
 652                         dev_err(&nvmem->dev,
 653                                 "Invalid keepout region.\n");
 654
 655                         return -EINVAL;
 656                 }
 657
 658                 /*
 659                  * Validate keepouts (and holes between) don't violate
 660                  * word_size constraints.
 661                  */
 662                 if ((keepout->end - keepout->start < nvmem->word_size) ||
 663                     ((keepout->start != cur) &&
 664                      (keepout->start - cur < nvmem->word_size))) {
 665
 666                         dev_err(&nvmem->dev,
 667                                 "Keepout regions violate word_size constraints.\n");
 668
 669                         return -ERANGE;
 670                 }
 671
 672                 /* Validate keepouts don't violate stride (alignment). */
 673                 if (!IS_ALIGNED(keepout->start, nvmem->stride) ||
 674                     !IS_ALIGNED(keepout->end, nvmem->stride)) {
 675
 676                         dev_err(&nvmem->dev,
 677                                 "Keepout regions violate stride.\n");
 678
 679                         return -EINVAL;
 680                 }
 681
 682                 cur = keepout->end;
 683                 keepout++;
 684         }
 685
 686         return 0;
 687 }
 688
 689 static int nvmem_add_cells_from_of(struct nvmem_device *nvmem)
 690 {
 691         struct device *dev = &nvmem->dev;
 692         struct device_node *child;
 693         const __be32 *addr;
 694         int len, ret;
 695
 696         for_each_child_of_node(dev->of_node, child) {
 697                 struct nvmem_cell_info info = {0};
 698
 699                 addr = of_get_property(child, "reg", &len);
 700                 if (!addr)
 701                         continue;
 702                 if (len < 2 * sizeof(u32)) {
 703                         dev_err(dev, "nvmem: invalid reg on %pOF\n", child);
 704                         of_node_put(child);
 705                         return -EINVAL;
 706                 }
 707
 708                 info.offset = be32_to_cpup(addr++);
 709                 info.bytes = be32_to_cpup(addr);
 710                 info.name = kasprintf(GFP_KERNEL, "%pOFn", child);
 711
 712                 addr = of_get_property(child, "bits", &len);
 713                 if (addr && len == (2 * sizeof(u32))) {
 714                         info.bit_offset = be32_to_cpup(addr++);
 715                         info.nbits = be32_to_cpup(addr);
 716                 }
 717
 718                 info.np = of_node_get(child);
 719
 720                 ret = nvmem_add_one_cell(nvmem, &info);
 721                 kfree(info.name);
 722                 if (ret) {
 723                         of_node_put(child);
 724                         return ret;
 725                 }
 726         }
 727
 728         return 0;
 729 }
 730
 731 /**
 732  * nvmem_register() - Register a nvmem device for given nvmem_config.
 733  * Also creates a binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
 734  *
 735  * @config: nvmem device configuration with which nvmem device is created.
 736  *
 737  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
 738  * on success.
 739  */
 740
 741 struct nvmem_device *nvmem_register(const struct nvmem_config *config)
 742 {
 743         struct nvmem_device *nvmem;
 744         int rval;
 745
 746         if (!config->dev)
 747                 return ERR_PTR(-EINVAL);
 748
 749         if (!config->reg_read && !config->reg_write)
 750                 return ERR_PTR(-EINVAL);
 751
 752         nvmem = kzalloc(sizeof(*nvmem), GFP_KERNEL);
 753         if (!nvmem)
 754                 return ERR_PTR(-ENOMEM);
 755
 756         rval = ida_alloc(&nvmem_ida, GFP_KERNEL);
 757         if (rval < 0) {
 758                 kfree(nvmem);
 759                 return ERR_PTR(rval);
 760         }
 761
 762         nvmem->id = rval;
 763
 764         nvmem->dev.type = &nvmem_provider_type;
 765         nvmem->dev.bus = &nvmem_bus_type;
 766         nvmem->dev.parent = config->dev;
 767
 768         device_initialize(&nvmem->dev);
 769
 770         if (!config->ignore_wp)
 771                 nvmem->wp_gpio = gpiod_get_optional(config->dev, "wp",
 772                                                     GPIOD_OUT_HIGH);
 773         if (IS_ERR(nvmem->wp_gpio)) {
 774                 rval = PTR_ERR(nvmem->wp_gpio);
 775                 nvmem->wp_gpio = NULL;
 776                 goto err_put_device;
 777         }
 778
 779         kref_init(&nvmem->refcnt);
 780         INIT_LIST_HEAD(&nvmem->cells);
 781
 782         nvmem->owner = config->owner;
 783         if (!nvmem->owner && config->dev->driver)
 784                 nvmem->owner = config->dev->driver->owner;
 785         nvmem->stride = config->stride ?: 1;
 786         nvmem->word_size = config->word_size ?: 1;
 787         nvmem->size = config->size;
 788         nvmem->root_only = config->root_only;
 789         nvmem->priv = config->priv;
 790         nvmem->type = config->type;
 791         nvmem->reg_read = config->reg_read;
 792         nvmem->reg_write = config->reg_write;
 793         nvmem->cell_post_process = config->cell_post_process;
 794         nvmem->keepout = config->keepout;
 795         nvmem->nkeepout = config->nkeepout;
 796         if (config->of_node)
 797                 nvmem->dev.of_node = config->of_node;
 798         else if (!config->no_of_node)
 799                 nvmem->dev.of_node = config->dev->of_node;
 800
 801         switch (config->id) {
 802         case NVMEM_DEVID_NONE:
 803                 rval = dev_set_name(&nvmem->dev, "%s", config->name);
 804                 break;
 805         case NVMEM_DEVID_AUTO:
 806                 rval = dev_set_name(&nvmem->dev, "%s%d", config->name, nvmem->id);
 807                 break;
 808         default:
 809                 rval = dev_set_name(&nvmem->dev, "%s%d",
 810                              config->name ? : "nvmem",
 811                              config->name ? config->id : nvmem->id);
 812                 break;
 813         }
 814
 815         if (rval)
 816                 goto err_put_device;
 817
 818         nvmem->read_only = device_property_present(config->dev, "read-only") ||
 819                            config->read_only || !nvmem->reg_write;
 820
 821 #ifdef CONFIG_NVMEM_SYSFS
 822         nvmem->dev.groups = nvmem_dev_groups;
 823 #endif
 824
 825         if (nvmem->nkeepout) {
 826                 rval = nvmem_validate_keepouts(nvmem);
 827                 if (rval)
 828                         goto err_put_device;
 829         }
 830
 831         if (config->compat) {
 832                 rval = nvmem_sysfs_setup_compat(nvmem, config);
 833                 if (rval)
 834                         goto err_put_device;
 835         }
 836
 837         if (config->cells) {
 838                 rval = nvmem_add_cells(nvmem, config->cells, config->ncells);
 839                 if (rval)
 840                         goto err_remove_cells;
 841         }
 842
 843         rval = nvmem_add_cells_from_table(nvmem);
 844         if (rval)
 845                 goto err_remove_cells;
 846
 847         rval = nvmem_add_cells_from_of(nvmem);
 848         if (rval)
 849                 goto err_remove_cells;
 850
 851         dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
 852
 853         rval = device_add(&nvmem->dev);
 854         if (rval)
 855                 goto err_remove_cells;
 856
 857         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem);
 858
 859         return nvmem;
 860
 861 err_remove_cells:
 862         nvmem_device_remove_all_cells(nvmem);
 863         if (config->compat)
 864                 nvmem_sysfs_remove_compat(nvmem, config);
 865 err_put_device:
 866         put_device(&nvmem->dev);
 867
 868         return ERR_PTR(rval);
 869 }
 870 EXPORT_SYMBOL_GPL(nvmem_register);
 871
 872 static void nvmem_device_release(struct kref *kref)
 873 {
 874         struct nvmem_device *nvmem;
 875
 876         nvmem = container_of(kref, struct nvmem_device, refcnt);
 877
 878         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_REMOVE, nvmem);
 879
 880         if (nvmem->flags & FLAG_COMPAT)
 881                 device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
 882
 883         nvmem_device_remove_all_cells(nvmem);
 884         device_unregister(&nvmem->dev);
 885 }
 886
 887 /**
 888  * nvmem_unregister() - Unregister previously registered nvmem device
 889  *
 890  * @nvmem: Pointer to previously registered nvmem device.
 891  */
 892 void nvmem_unregister(struct nvmem_device *nvmem)
 893 {
 894         if (nvmem)
 895                 kref_put(&nvmem->refcnt, nvmem_device_release);
 896 }
 897 EXPORT_SYMBOL_GPL(nvmem_unregister);
 898
 899 static void devm_nvmem_unregister(void *nvmem)
 900 {
 901         nvmem_unregister(nvmem);
 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 *nvmem;
 919         int ret;
 920
 921         nvmem = nvmem_register(config);
 922         if (IS_ERR(nvmem))
 923                 return nvmem;
 924
 925         ret = devm_add_action_or_reset(dev, devm_nvmem_unregister, nvmem);
 926         if (ret)
 927                 return ERR_PTR(ret);
 928
 929         return nvmem;
 930 }
 931 EXPORT_SYMBOL_GPL(devm_nvmem_register);
 932
 933 static struct nvmem_device *__nvmem_device_get(void *data,
 934                         int (*match)(struct device *dev, const void *data))
 935 {
 936         struct nvmem_device *nvmem = NULL;
 937         struct device *dev;
 938
 939         mutex_lock(&nvmem_mutex);
 940         dev = bus_find_device(&nvmem_bus_type, NULL, data, match);
 941         if (dev)
 942                 nvmem = to_nvmem_device(dev);
 943         mutex_unlock(&nvmem_mutex);
 944         if (!nvmem)
 945                 return ERR_PTR(-EPROBE_DEFER);
 946
 947         if (!try_module_get(nvmem->owner)) {
 948                 dev_err(&nvmem->dev,
 949                         "could not increase module refcount for cell %s\n",
 950                         nvmem_dev_name(nvmem));
 951
 952                 put_device(&nvmem->dev);
 953                 return ERR_PTR(-EINVAL);
 954         }
 955
 956         kref_get(&nvmem->refcnt);
 957
 958         return nvmem;
 959 }
 960
 961 static void __nvmem_device_put(struct nvmem_device *nvmem)
 962 {
 963         put_device(&nvmem->dev);
 964         module_put(nvmem->owner);
 965         kref_put(&nvmem->refcnt, nvmem_device_release);
 966 }
 967
 968 #if IS_ENABLED(CONFIG_OF)
 969 /**
 970  * of_nvmem_device_get() - Get nvmem device from a given id
 971  *
 972  * @np: Device tree node that uses the nvmem device.
 973  * @id: nvmem name from nvmem-names property.
 974  *
 975  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
 976  * on success.
 977  */
 978 struct nvmem_device *of_nvmem_device_get(struct device_node *np, const char *id)
 979 {
 980
 981         struct device_node *nvmem_np;
 982         struct nvmem_device *nvmem;
 983         int index = 0;
 984
 985         if (id)
 986                 index = of_property_match_string(np, "nvmem-names", id);
 987
 988         nvmem_np = of_parse_phandle(np, "nvmem", index);
 989         if (!nvmem_np)
 990                 return ERR_PTR(-ENOENT);
 991
 992         nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
 993         of_node_put(nvmem_np);
 994         return nvmem;
 995 }
 996 EXPORT_SYMBOL_GPL(of_nvmem_device_get);
 997 #endif
 998
 999 /**
1000  * nvmem_device_get() - Get nvmem device from a given id
1001  *
1002  * @dev: Device that uses the nvmem device.
1003  * @dev_name: name of the requested nvmem device.
1004  *
1005  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1006  * on success.
1007  */
1008 struct nvmem_device *nvmem_device_get(struct device *dev, const char *dev_name)
1009 {
1010         if (dev->of_node) { /* try dt first */
1011                 struct nvmem_device *nvmem;
1012
1013                 nvmem = of_nvmem_device_get(dev->of_node, dev_name);
1014
1015                 if (!IS_ERR(nvmem) || PTR_ERR(nvmem) == -EPROBE_DEFER)
1016                         return nvmem;
1017
1018         }
1019
1020         return __nvmem_device_get((void *)dev_name, device_match_name);
1021 }
1022 EXPORT_SYMBOL_GPL(nvmem_device_get);
1023
1024 /**
1025  * nvmem_device_find() - Find nvmem device with matching function
1026  *
1027  * @data: Data to pass to match function
1028  * @match: Callback function to check device
1029  *
1030  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1031  * on success.
1032  */
1033 struct nvmem_device *nvmem_device_find(void *data,
1034                         int (*match)(struct device *dev, const void *data))
1035 {
1036         return __nvmem_device_get(data, match);
1037 }
1038 EXPORT_SYMBOL_GPL(nvmem_device_find);
1039
1040 static int devm_nvmem_device_match(struct device *dev, void *res, void *data)
1041 {
1042         struct nvmem_device **nvmem = res;
1043
1044         if (WARN_ON(!nvmem || !*nvmem))
1045                 return 0;
1046
1047         return *nvmem == data;
1048 }
1049
1050 static void devm_nvmem_device_release(struct device *dev, void *res)
1051 {
1052         nvmem_device_put(*(struct nvmem_device **)res);
1053 }
1054
1055 /**
1056  * devm_nvmem_device_put() - put alredy got nvmem device
1057  *
1058  * @dev: Device that uses the nvmem device.
1059  * @nvmem: pointer to nvmem device allocated by devm_nvmem_cell_get(),
1060  * that needs to be released.
1061  */
1062 void devm_nvmem_device_put(struct device *dev, struct nvmem_device *nvmem)
1063 {
1064         int ret;
1065
1066         ret = devres_release(dev, devm_nvmem_device_release,
1067                              devm_nvmem_device_match, nvmem);
1068
1069         WARN_ON(ret);
1070 }
1071 EXPORT_SYMBOL_GPL(devm_nvmem_device_put);
1072
1073 /**
1074  * nvmem_device_put() - put alredy got nvmem device
1075  *
1076  * @nvmem: pointer to nvmem device that needs to be released.
1077  */
1078 void nvmem_device_put(struct nvmem_device *nvmem)
1079 {
1080         __nvmem_device_put(nvmem);
1081 }
1082 EXPORT_SYMBOL_GPL(nvmem_device_put);
1083
1084 /**
1085  * devm_nvmem_device_get() - Get nvmem cell of device form a given id
1086  *
1087  * @dev: Device that requests the nvmem device.
1088  * @id: name id for the requested nvmem device.
1089  *
1090  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_cell
1091  * on success.  The nvmem_cell will be freed by the automatically once the
1092  * device is freed.
1093  */
1094 struct nvmem_device *devm_nvmem_device_get(struct device *dev, const char *id)
1095 {
1096         struct nvmem_device **ptr, *nvmem;
1097
1098         ptr = devres_alloc(devm_nvmem_device_release, sizeof(*ptr), GFP_KERNEL);
1099         if (!ptr)
1100                 return ERR_PTR(-ENOMEM);
1101
1102         nvmem = nvmem_device_get(dev, id);
1103         if (!IS_ERR(nvmem)) {
1104                 *ptr = nvmem;
1105                 devres_add(dev, ptr);
1106         } else {
1107                 devres_free(ptr);
1108         }
1109
1110         return nvmem;
1111 }
1112 EXPORT_SYMBOL_GPL(devm_nvmem_device_get);
1113
1114 static struct nvmem_cell *nvmem_create_cell(struct nvmem_cell_entry *entry,
1115                                             const char *id, int index)
1116 {
1117         struct nvmem_cell *cell;
1118         const char *name = NULL;
1119
1120         cell = kzalloc(sizeof(*cell), GFP_KERNEL);
1121         if (!cell)
1122                 return ERR_PTR(-ENOMEM);
1123
1124         if (id) {
1125                 name = kstrdup_const(id, GFP_KERNEL);
1126                 if (!name) {
1127                         kfree(cell);
1128                         return ERR_PTR(-ENOMEM);
1129                 }
1130         }
1131
1132         cell->id = name;
1133         cell->entry = entry;
1134         cell->index = index;
1135
1136         return cell;
1137 }
1138
1139 static struct nvmem_cell *
1140 nvmem_cell_get_from_lookup(struct device *dev, const char *con_id)
1141 {
1142         struct nvmem_cell_entry *cell_entry;
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_entry = nvmem_find_cell_entry_by_name(nvmem,
1168                                                                    lookup->cell_name);
1169                         if (!cell_entry) {
1170                                 __nvmem_device_put(nvmem);
1171                                 cell = ERR_PTR(-ENOENT);
1172                         } else {
1173                                 cell = nvmem_create_cell(cell_entry, con_id, 0);
1174                                 if (IS_ERR(cell))
1175                                         __nvmem_device_put(nvmem);
1176                         }
1177                         break;
1178                 }
1179         }
1180
1181         mutex_unlock(&nvmem_lookup_mutex);
1182         return cell;
1183 }
1184
1185 #if IS_ENABLED(CONFIG_OF)
1186 static struct nvmem_cell_entry *
1187 nvmem_find_cell_entry_by_node(struct nvmem_device *nvmem, struct device_node *np)
1188 {
1189         struct nvmem_cell_entry *iter, *cell = NULL;
1190
1191         mutex_lock(&nvmem_mutex);
1192         list_for_each_entry(iter, &nvmem->cells, node) {
1193                 if (np == iter->np) {
1194                         cell = iter;
1195                         break;
1196                 }
1197         }
1198         mutex_unlock(&nvmem_mutex);
1199
1200         return cell;
1201 }
1202
1203 /**
1204  * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
1205  *
1206  * @np: Device tree node that uses the nvmem cell.
1207  * @id: nvmem cell name from nvmem-cell-names property, or NULL
1208  *      for the cell at index 0 (the lone cell with no accompanying
1209  *      nvmem-cell-names property).
1210  *
1211  * Return: Will be an ERR_PTR() on error or a valid pointer
1212  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1213  * nvmem_cell_put().
1214  */
1215 struct nvmem_cell *of_nvmem_cell_get(struct device_node *np, const char *id)
1216 {
1217         struct device_node *cell_np, *nvmem_np;
1218         struct nvmem_device *nvmem;
1219         struct nvmem_cell_entry *cell_entry;
1220         struct nvmem_cell *cell;
1221         struct of_phandle_args cell_spec;
1222         int index = 0;
1223         int cell_index = 0;
1224         int ret;
1225
1226         /* if cell name exists, find index to the name */
1227         if (id)
1228                 index = of_property_match_string(np, "nvmem-cell-names", id);
1229
1230         ret = of_parse_phandle_with_optional_args(np, "nvmem-cells",
1231                                                   "#nvmem-cell-cells",
1232                                                   index, &cell_spec);
1233         if (ret)
1234                 return ERR_PTR(ret);
1235
1236         if (cell_spec.args_count > 1)
1237                 return ERR_PTR(-EINVAL);
1238
1239         cell_np = cell_spec.np;
1240         if (cell_spec.args_count)
1241                 cell_index = cell_spec.args[0];
1242
1243         nvmem_np = of_get_parent(cell_np);
1244         if (!nvmem_np) {
1245                 of_node_put(cell_np);
1246                 return ERR_PTR(-EINVAL);
1247         }
1248
1249         nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
1250         of_node_put(nvmem_np);
1251         if (IS_ERR(nvmem)) {
1252                 of_node_put(cell_np);
1253                 return ERR_CAST(nvmem);
1254         }
1255
1256         cell_entry = nvmem_find_cell_entry_by_node(nvmem, cell_np);
1257         of_node_put(cell_np);
1258         if (!cell_entry) {
1259                 __nvmem_device_put(nvmem);
1260                 return ERR_PTR(-ENOENT);
1261         }
1262
1263         cell = nvmem_create_cell(cell_entry, id, cell_index);
1264         if (IS_ERR(cell))
1265                 __nvmem_device_put(nvmem);
1266
1267         return cell;
1268 }
1269 EXPORT_SYMBOL_GPL(of_nvmem_cell_get);
1270 #endif
1271
1272 /**
1273  * nvmem_cell_get() - Get nvmem cell of device form a given cell name
1274  *
1275  * @dev: Device that requests the nvmem cell.
1276  * @id: nvmem cell name to get (this corresponds with the name from the
1277  *      nvmem-cell-names property for DT systems and with the con_id from
1278  *      the lookup entry for non-DT systems).
1279  *
1280  * Return: Will be an ERR_PTR() on error or a valid pointer
1281  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1282  * nvmem_cell_put().
1283  */
1284 struct nvmem_cell *nvmem_cell_get(struct device *dev, const char *id)
1285 {
1286         struct nvmem_cell *cell;
1287
1288         if (dev->of_node) { /* try dt first */
1289                 cell = of_nvmem_cell_get(dev->of_node, id);
1290                 if (!IS_ERR(cell) || PTR_ERR(cell) == -EPROBE_DEFER)
1291                         return cell;
1292         }
1293
1294         /* NULL cell id only allowed for device tree; invalid otherwise */
1295         if (!id)
1296                 return ERR_PTR(-EINVAL);
1297
1298         return nvmem_cell_get_from_lookup(dev, id);
1299 }
1300 EXPORT_SYMBOL_GPL(nvmem_cell_get);
1301
1302 static void devm_nvmem_cell_release(struct device *dev, void *res)
1303 {
1304         nvmem_cell_put(*(struct nvmem_cell **)res);
1305 }
1306
1307 /**
1308  * devm_nvmem_cell_get() - Get nvmem cell of device form a given id
1309  *
1310  * @dev: Device that requests the nvmem cell.
1311  * @id: nvmem cell name id to get.
1312  *
1313  * Return: Will be an ERR_PTR() on error or a valid pointer
1314  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1315  * automatically once the device is freed.
1316  */
1317 struct nvmem_cell *devm_nvmem_cell_get(struct device *dev, const char *id)
1318 {
1319         struct nvmem_cell **ptr, *cell;
1320
1321         ptr = devres_alloc(devm_nvmem_cell_release, sizeof(*ptr), GFP_KERNEL);
1322         if (!ptr)
1323                 return ERR_PTR(-ENOMEM);
1324
1325         cell = nvmem_cell_get(dev, id);
1326         if (!IS_ERR(cell)) {
1327                 *ptr = cell;
1328                 devres_add(dev, ptr);
1329         } else {
1330                 devres_free(ptr);
1331         }
1332
1333         return cell;
1334 }
1335 EXPORT_SYMBOL_GPL(devm_nvmem_cell_get);
1336
1337 static int devm_nvmem_cell_match(struct device *dev, void *res, void *data)
1338 {
1339         struct nvmem_cell **c = res;
1340
1341         if (WARN_ON(!c || !*c))
1342                 return 0;
1343
1344         return *c == data;
1345 }
1346
1347 /**
1348  * devm_nvmem_cell_put() - Release previously allocated nvmem cell
1349  * from devm_nvmem_cell_get.
1350  *
1351  * @dev: Device that requests the nvmem cell.
1352  * @cell: Previously allocated nvmem cell by devm_nvmem_cell_get().
1353  */
1354 void devm_nvmem_cell_put(struct device *dev, struct nvmem_cell *cell)
1355 {
1356         int ret;
1357
1358         ret = devres_release(dev, devm_nvmem_cell_release,
1359                                 devm_nvmem_cell_match, cell);
1360
1361         WARN_ON(ret);
1362 }
1363 EXPORT_SYMBOL(devm_nvmem_cell_put);
1364
1365 /**
1366  * nvmem_cell_put() - Release previously allocated nvmem cell.
1367  *
1368  * @cell: Previously allocated nvmem cell by nvmem_cell_get().
1369  */
1370 void nvmem_cell_put(struct nvmem_cell *cell)
1371 {
1372         struct nvmem_device *nvmem = cell->entry->nvmem;
1373
1374         if (cell->id)
1375                 kfree_const(cell->id);
1376
1377         kfree(cell);
1378         __nvmem_device_put(nvmem);
1379 }
1380 EXPORT_SYMBOL_GPL(nvmem_cell_put);
1381
1382 static void nvmem_shift_read_buffer_in_place(struct nvmem_cell_entry *cell, void *buf)
1383 {
1384         u8 *p, *b;
1385         int i, extra, bit_offset = cell->bit_offset;
1386
1387         p = b = buf;
1388         if (bit_offset) {
1389                 /* First shift */
1390                 *b++ >>= bit_offset;
1391
1392                 /* setup rest of the bytes if any */
1393                 for (i = 1; i < cell->bytes; i++) {
1394                         /* Get bits from next byte and shift them towards msb */
1395                         *p |= *b << (BITS_PER_BYTE - bit_offset);
1396
1397                         p = b;
1398                         *b++ >>= bit_offset;
1399                 }
1400         } else {
1401                 /* point to the msb */
1402                 p += cell->bytes - 1;
1403         }
1404
1405         /* result fits in less bytes */
1406         extra = cell->bytes - DIV_ROUND_UP(cell->nbits, BITS_PER_BYTE);
1407         while (--extra >= 0)
1408                 *p-- = 0;
1409
1410         /* clear msb bits if any leftover in the last byte */
1411         if (cell->nbits % BITS_PER_BYTE)
1412                 *p &= GENMASK((cell->nbits % BITS_PER_BYTE) - 1, 0);
1413 }
1414
1415 static int __nvmem_cell_read(struct nvmem_device *nvmem,
1416                              struct nvmem_cell_entry *cell,
1417                              void *buf, size_t *len, const char *id, int index)
1418 {
1419         int rc;
1420
1421         rc = nvmem_reg_read(nvmem, cell->offset, buf, cell->bytes);
1422
1423         if (rc)
1424                 return rc;
1425
1426         /* shift bits in-place */
1427         if (cell->bit_offset || cell->nbits)
1428                 nvmem_shift_read_buffer_in_place(cell, buf);
1429
1430         if (nvmem->cell_post_process) {
1431                 rc = nvmem->cell_post_process(nvmem->priv, id, index,
1432                                               cell->offset, buf, cell->bytes);
1433                 if (rc)
1434                         return rc;
1435         }
1436
1437         if (len)
1438                 *len = cell->bytes;
1439
1440         return 0;
1441 }
1442
1443 /**
1444  * nvmem_cell_read() - Read a given nvmem cell
1445  *
1446  * @cell: nvmem cell to be read.
1447  * @len: pointer to length of cell which will be populated on successful read;
1448  *       can be NULL.
1449  *
1450  * Return: ERR_PTR() on error or a valid pointer to a buffer on success. The
1451  * buffer should be freed by the consumer with a kfree().
1452  */
1453 void *nvmem_cell_read(struct nvmem_cell *cell, size_t *len)
1454 {
1455         struct nvmem_device *nvmem = cell->entry->nvmem;
1456         u8 *buf;
1457         int rc;
1458
1459         if (!nvmem)
1460                 return ERR_PTR(-EINVAL);
1461
1462         buf = kzalloc(cell->entry->bytes, GFP_KERNEL);
1463         if (!buf)
1464                 return ERR_PTR(-ENOMEM);
1465
1466         rc = __nvmem_cell_read(nvmem, cell->entry, buf, len, cell->id, cell->index);
1467         if (rc) {
1468                 kfree(buf);
1469                 return ERR_PTR(rc);
1470         }
1471
1472         return buf;
1473 }
1474 EXPORT_SYMBOL_GPL(nvmem_cell_read);
1475
1476 static void *nvmem_cell_prepare_write_buffer(struct nvmem_cell_entry *cell,
1477                                              u8 *_buf, int len)
1478 {
1479         struct nvmem_device *nvmem = cell->nvmem;
1480         int i, rc, nbits, bit_offset = cell->bit_offset;
1481         u8 v, *p, *buf, *b, pbyte, pbits;
1482
1483         nbits = cell->nbits;
1484         buf = kzalloc(cell->bytes, GFP_KERNEL);
1485         if (!buf)
1486                 return ERR_PTR(-ENOMEM);
1487
1488         memcpy(buf, _buf, len);
1489         p = b = buf;
1490
1491         if (bit_offset) {
1492                 pbyte = *b;
1493                 *b <<= bit_offset;
1494
1495                 /* setup the first byte with lsb bits from nvmem */
1496                 rc = nvmem_reg_read(nvmem, cell->offset, &v, 1);
1497                 if (rc)
1498                         goto err;
1499                 *b++ |= GENMASK(bit_offset - 1, 0) & v;
1500
1501                 /* setup rest of the byte if any */
1502                 for (i = 1; i < cell->bytes; i++) {
1503                         /* Get last byte bits and shift them towards lsb */
1504                         pbits = pbyte >> (BITS_PER_BYTE - 1 - bit_offset);
1505                         pbyte = *b;
1506                         p = b;
1507                         *b <<= bit_offset;
1508                         *b++ |= pbits;
1509                 }
1510         }
1511
1512         /* if it's not end on byte boundary */
1513         if ((nbits + bit_offset) % BITS_PER_BYTE) {
1514                 /* setup the last byte with msb bits from nvmem */
1515                 rc = nvmem_reg_read(nvmem,
1516                                     cell->offset + cell->bytes - 1, &v, 1);
1517                 if (rc)
1518                         goto err;
1519                 *p |= GENMASK(7, (nbits + bit_offset) % BITS_PER_BYTE) & v;
1520
1521         }
1522
1523         return buf;
1524 err:
1525         kfree(buf);
1526         return ERR_PTR(rc);
1527 }
1528
1529 static int __nvmem_cell_entry_write(struct nvmem_cell_entry *cell, void *buf, size_t len)
1530 {
1531         struct nvmem_device *nvmem = cell->nvmem;
1532         int rc;
1533
1534         if (!nvmem || nvmem->read_only ||
1535             (cell->bit_offset == 0 && len != cell->bytes))
1536                 return -EINVAL;
1537
1538         if (cell->bit_offset || cell->nbits) {
1539                 buf = nvmem_cell_prepare_write_buffer(cell, buf, len);
1540                 if (IS_ERR(buf))
1541                         return PTR_ERR(buf);
1542         }
1543
1544         rc = nvmem_reg_write(nvmem, cell->offset, buf, cell->bytes);
1545
1546         /* free the tmp buffer */
1547         if (cell->bit_offset || cell->nbits)
1548                 kfree(buf);
1549
1550         if (rc)
1551                 return rc;
1552
1553         return len;
1554 }
1555
1556 /**
1557  * nvmem_cell_write() - Write to a given nvmem cell
1558  *
1559  * @cell: nvmem cell to be written.
1560  * @buf: Buffer to be written.
1561  * @len: length of buffer to be written to nvmem cell.
1562  *
1563  * Return: length of bytes written or negative on failure.
1564  */
1565 int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len)
1566 {
1567         return __nvmem_cell_entry_write(cell->entry, buf, len);
1568 }
1569
1570 EXPORT_SYMBOL_GPL(nvmem_cell_write);
1571
1572 static int nvmem_cell_read_common(struct device *dev, const char *cell_id,
1573                                   void *val, size_t count)
1574 {
1575         struct nvmem_cell *cell;
1576         void *buf;
1577         size_t len;
1578
1579         cell = nvmem_cell_get(dev, cell_id);
1580         if (IS_ERR(cell))
1581                 return PTR_ERR(cell);
1582
1583         buf = nvmem_cell_read(cell, &len);
1584         if (IS_ERR(buf)) {
1585                 nvmem_cell_put(cell);
1586                 return PTR_ERR(buf);
1587         }
1588         if (len != count) {
1589                 kfree(buf);
1590                 nvmem_cell_put(cell);
1591                 return -EINVAL;
1592         }
1593         memcpy(val, buf, count);
1594         kfree(buf);
1595         nvmem_cell_put(cell);
1596
1597         return 0;
1598 }
1599
1600 /**
1601  * nvmem_cell_read_u8() - Read a cell value as a u8
1602  *
1603  * @dev: Device that requests the nvmem cell.
1604  * @cell_id: Name of nvmem cell to read.
1605  * @val: pointer to output value.
1606  *
1607  * Return: 0 on success or negative errno.
1608  */
1609 int nvmem_cell_read_u8(struct device *dev, const char *cell_id, u8 *val)
1610 {
1611         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1612 }
1613 EXPORT_SYMBOL_GPL(nvmem_cell_read_u8);
1614
1615 /**
1616  * nvmem_cell_read_u16() - Read a cell value as a u16
1617  *
1618  * @dev: Device that requests the nvmem cell.
1619  * @cell_id: Name of nvmem cell to read.
1620  * @val: pointer to output value.
1621  *
1622  * Return: 0 on success or negative errno.
1623  */
1624 int nvmem_cell_read_u16(struct device *dev, const char *cell_id, u16 *val)
1625 {
1626         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1627 }
1628 EXPORT_SYMBOL_GPL(nvmem_cell_read_u16);
1629
1630 /**
1631  * nvmem_cell_read_u32() - Read a cell value as a u32
1632  *
1633  * @dev: Device that requests the nvmem cell.
1634  * @cell_id: Name of nvmem cell to read.
1635  * @val: pointer to output value.
1636  *
1637  * Return: 0 on success or negative errno.
1638  */
1639 int nvmem_cell_read_u32(struct device *dev, const char *cell_id, u32 *val)
1640 {
1641         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1642 }
1643 EXPORT_SYMBOL_GPL(nvmem_cell_read_u32);
1644
1645 /**
1646  * nvmem_cell_read_u64() - Read a cell value as a u64
1647  *
1648  * @dev: Device that requests the nvmem cell.
1649  * @cell_id: Name of nvmem cell to read.
1650  * @val: pointer to output value.
1651  *
1652  * Return: 0 on success or negative errno.
1653  */
1654 int nvmem_cell_read_u64(struct device *dev, const char *cell_id, u64 *val)
1655 {
1656         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1657 }
1658 EXPORT_SYMBOL_GPL(nvmem_cell_read_u64);
1659
1660 static const void *nvmem_cell_read_variable_common(struct device *dev,
1661                                                    const char *cell_id,
1662                                                    size_t max_len, size_t *len)
1663 {
1664         struct nvmem_cell *cell;
1665         int nbits;
1666         void *buf;
1667
1668         cell = nvmem_cell_get(dev, cell_id);
1669         if (IS_ERR(cell))
1670                 return cell;
1671
1672         nbits = cell->entry->nbits;
1673         buf = nvmem_cell_read(cell, len);
1674         nvmem_cell_put(cell);
1675         if (IS_ERR(buf))
1676                 return buf;
1677
1678         /*
1679          * If nbits is set then nvmem_cell_read() can significantly exaggerate
1680          * the length of the real data. Throw away the extra junk.
1681          */
1682         if (nbits)
1683                 *len = DIV_ROUND_UP(nbits, 8);
1684
1685         if (*len > max_len) {
1686                 kfree(buf);
1687                 return ERR_PTR(-ERANGE);
1688         }
1689
1690         return buf;
1691 }
1692
1693 /**
1694  * nvmem_cell_read_variable_le_u32() - Read up to 32-bits of data as a little endian number.
1695  *
1696  * @dev: Device that requests the nvmem cell.
1697  * @cell_id: Name of nvmem cell to read.
1698  * @val: pointer to output value.
1699  *
1700  * Return: 0 on success or negative errno.
1701  */
1702 int nvmem_cell_read_variable_le_u32(struct device *dev, const char *cell_id,
1703                                     u32 *val)
1704 {
1705         size_t len;
1706         const u8 *buf;
1707         int i;
1708
1709         buf = nvmem_cell_read_variable_common(dev, cell_id, sizeof(*val), &len);
1710         if (IS_ERR(buf))
1711                 return PTR_ERR(buf);
1712
1713         /* Copy w/ implicit endian conversion */
1714         *val = 0;
1715         for (i = 0; i < len; i++)
1716                 *val |= buf[i] << (8 * i);
1717
1718         kfree(buf);
1719
1720         return 0;
1721 }
1722 EXPORT_SYMBOL_GPL(nvmem_cell_read_variable_le_u32);
1723
1724 /**
1725  * nvmem_cell_read_variable_le_u64() - Read up to 64-bits of data as a little endian number.
1726  *
1727  * @dev: Device that requests the nvmem cell.
1728  * @cell_id: Name of nvmem cell to read.
1729  * @val: pointer to output value.
1730  *
1731  * Return: 0 on success or negative errno.
1732  */
1733 int nvmem_cell_read_variable_le_u64(struct device *dev, const char *cell_id,
1734                                     u64 *val)
1735 {
1736         size_t len;
1737         const u8 *buf;
1738         int i;
1739
1740         buf = nvmem_cell_read_variable_common(dev, cell_id, sizeof(*val), &len);
1741         if (IS_ERR(buf))
1742                 return PTR_ERR(buf);
1743
1744         /* Copy w/ implicit endian conversion */
1745         *val = 0;
1746         for (i = 0; i < len; i++)
1747                 *val |= (uint64_t)buf[i] << (8 * i);
1748
1749         kfree(buf);
1750
1751         return 0;
1752 }
1753 EXPORT_SYMBOL_GPL(nvmem_cell_read_variable_le_u64);
1754
1755 /**
1756  * nvmem_device_cell_read() - Read a given nvmem device and cell
1757  *
1758  * @nvmem: nvmem device to read from.
1759  * @info: nvmem cell info to be read.
1760  * @buf: buffer pointer which will be populated on successful read.
1761  *
1762  * Return: length of successful bytes read on success and negative
1763  * error code on error.
1764  */
1765 ssize_t nvmem_device_cell_read(struct nvmem_device *nvmem,
1766                            struct nvmem_cell_info *info, void *buf)
1767 {
1768         struct nvmem_cell_entry cell;
1769         int rc;
1770         ssize_t len;
1771
1772         if (!nvmem)
1773                 return -EINVAL;
1774
1775         rc = nvmem_cell_info_to_nvmem_cell_entry_nodup(nvmem, info, &cell);
1776         if (rc)
1777                 return rc;
1778
1779         rc = __nvmem_cell_read(nvmem, &cell, buf, &len, NULL, 0);
1780         if (rc)
1781                 return rc;
1782
1783         return len;
1784 }
1785 EXPORT_SYMBOL_GPL(nvmem_device_cell_read);
1786
1787 /**
1788  * nvmem_device_cell_write() - Write cell to a given nvmem device
1789  *
1790  * @nvmem: nvmem device to be written to.
1791  * @info: nvmem cell info to be written.
1792  * @buf: buffer to be written to cell.
1793  *
1794  * Return: length of bytes written or negative error code on failure.
1795  */
1796 int nvmem_device_cell_write(struct nvmem_device *nvmem,
1797                             struct nvmem_cell_info *info, void *buf)
1798 {
1799         struct nvmem_cell_entry cell;
1800         int rc;
1801
1802         if (!nvmem)
1803                 return -EINVAL;
1804
1805         rc = nvmem_cell_info_to_nvmem_cell_entry_nodup(nvmem, info, &cell);
1806         if (rc)
1807                 return rc;
1808
1809         return __nvmem_cell_entry_write(&cell, buf, cell.bytes);
1810 }
1811 EXPORT_SYMBOL_GPL(nvmem_device_cell_write);
1812
1813 /**
1814  * nvmem_device_read() - Read from a given nvmem device
1815  *
1816  * @nvmem: nvmem device to read from.
1817  * @offset: offset in nvmem device.
1818  * @bytes: number of bytes to read.
1819  * @buf: buffer pointer which will be populated on successful read.
1820  *
1821  * Return: length of successful bytes read on success and negative
1822  * error code on error.
1823  */
1824 int nvmem_device_read(struct nvmem_device *nvmem,
1825                       unsigned int offset,
1826                       size_t bytes, void *buf)
1827 {
1828         int rc;
1829
1830         if (!nvmem)
1831                 return -EINVAL;
1832
1833         rc = nvmem_reg_read(nvmem, offset, buf, bytes);
1834
1835         if (rc)
1836                 return rc;
1837
1838         return bytes;
1839 }
1840 EXPORT_SYMBOL_GPL(nvmem_device_read);
1841
1842 /**
1843  * nvmem_device_write() - Write cell to a given nvmem device
1844  *
1845  * @nvmem: nvmem device to be written to.
1846  * @offset: offset in nvmem device.
1847  * @bytes: number of bytes to write.
1848  * @buf: buffer to be written.
1849  *
1850  * Return: length of bytes written or negative error code on failure.
1851  */
1852 int nvmem_device_write(struct nvmem_device *nvmem,
1853                        unsigned int offset,
1854                        size_t bytes, void *buf)
1855 {
1856         int rc;
1857
1858         if (!nvmem)
1859                 return -EINVAL;
1860
1861         rc = nvmem_reg_write(nvmem, offset, buf, bytes);
1862
1863         if (rc)
1864                 return rc;
1865
1866
1867         return bytes;
1868 }
1869 EXPORT_SYMBOL_GPL(nvmem_device_write);
1870
1871 /**
1872  * nvmem_add_cell_table() - register a table of cell info entries
1873  *
1874  * @table: table of cell info entries
1875  */
1876 void nvmem_add_cell_table(struct nvmem_cell_table *table)
1877 {
1878         mutex_lock(&nvmem_cell_mutex);
1879         list_add_tail(&table->node, &nvmem_cell_tables);
1880         mutex_unlock(&nvmem_cell_mutex);
1881 }
1882 EXPORT_SYMBOL_GPL(nvmem_add_cell_table);
1883
1884 /**
1885  * nvmem_del_cell_table() - remove a previously registered cell info table
1886  *
1887  * @table: table of cell info entries
1888  */
1889 void nvmem_del_cell_table(struct nvmem_cell_table *table)
1890 {
1891         mutex_lock(&nvmem_cell_mutex);
1892         list_del(&table->node);
1893         mutex_unlock(&nvmem_cell_mutex);
1894 }
1895 EXPORT_SYMBOL_GPL(nvmem_del_cell_table);
1896
1897 /**
1898  * nvmem_add_cell_lookups() - register a list of cell lookup entries
1899  *
1900  * @entries: array of cell lookup entries
1901  * @nentries: number of cell lookup entries in the array
1902  */
1903 void nvmem_add_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
1904 {
1905         int i;
1906
1907         mutex_lock(&nvmem_lookup_mutex);
1908         for (i = 0; i < nentries; i++)
1909                 list_add_tail(&entries[i].node, &nvmem_lookup_list);
1910         mutex_unlock(&nvmem_lookup_mutex);
1911 }
1912 EXPORT_SYMBOL_GPL(nvmem_add_cell_lookups);
1913
1914 /**
1915  * nvmem_del_cell_lookups() - remove a list of previously added cell lookup
1916  *                            entries
1917  *
1918  * @entries: array of cell lookup entries
1919  * @nentries: number of cell lookup entries in the array
1920  */
1921 void nvmem_del_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
1922 {
1923         int i;
1924
1925         mutex_lock(&nvmem_lookup_mutex);
1926         for (i = 0; i < nentries; i++)
1927                 list_del(&entries[i].node);
1928         mutex_unlock(&nvmem_lookup_mutex);
1929 }
1930 EXPORT_SYMBOL_GPL(nvmem_del_cell_lookups);
1931
1932 /**
1933  * nvmem_dev_name() - Get the name of a given nvmem device.
1934  *
1935  * @nvmem: nvmem device.
1936  *
1937  * Return: name of the nvmem device.
1938  */
1939 const char *nvmem_dev_name(struct nvmem_device *nvmem)
1940 {
1941         return dev_name(&nvmem->dev);
1942 }
1943 EXPORT_SYMBOL_GPL(nvmem_dev_name);
1944
1945 static int __init nvmem_init(void)
1946 {
1947         return bus_register(&nvmem_bus_type);
1948 }
1949
1950 static void __exit nvmem_exit(void)
1951 {
1952         bus_unregister(&nvmem_bus_type);
1953 }
1954
1955 subsys_initcall(nvmem_init);
1956 module_exit(nvmem_exit);
1957
1958 MODULE_AUTHOR("Srinivas Kandagatla <srinivas.kandagatla@linaro.org");
1959 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com");
1960 MODULE_DESCRIPTION("nvmem Driver Core");
1961 MODULE_LICENSE("GPL v2");