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