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 };
  64
  65 static DEFINE_MUTEX(nvmem_mutex);
  66 static DEFINE_IDA(nvmem_ida);
  67
  68 static DEFINE_MUTEX(nvmem_cell_mutex);
  69 static LIST_HEAD(nvmem_cell_tables);
  70
  71 static DEFINE_MUTEX(nvmem_lookup_mutex);
  72 static LIST_HEAD(nvmem_lookup_list);
  73
  74 static BLOCKING_NOTIFIER_HEAD(nvmem_notifier);
  75
  76 static int __nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
  77                             void *val, size_t bytes)
  78 {
  79         if (nvmem->reg_read)
  80                 return nvmem->reg_read(nvmem->priv, offset, val, bytes);
  81
  82         return -EINVAL;
  83 }
  84
  85 static int __nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
  86                              void *val, size_t bytes)
  87 {
  88         int ret;
  89
  90         if (nvmem->reg_write) {
  91                 gpiod_set_value_cansleep(nvmem->wp_gpio, 0);
  92                 ret = nvmem->reg_write(nvmem->priv, offset, val, bytes);
  93                 gpiod_set_value_cansleep(nvmem->wp_gpio, 1);
  94                 return ret;
  95         }
  96
  97         return -EINVAL;
  98 }
  99
 100 static int nvmem_access_with_keepouts(struct nvmem_device *nvmem,
 101                                       unsigned int offset, void *val,
 102                                       size_t bytes, int write)
 103 {
 104
 105         unsigned int end = offset + bytes;
 106         unsigned int kend, ksize;
 107         const struct nvmem_keepout *keepout = nvmem->keepout;
 108         const struct nvmem_keepout *keepoutend = keepout + nvmem->nkeepout;
 109         int rc;
 110
 111         /*
 112          * Skip all keepouts before the range being accessed.
 113          * Keepouts are sorted.
 114          */
 115         while ((keepout < keepoutend) && (keepout->end <= offset))
 116                 keepout++;
 117
 118         while ((offset < end) && (keepout < keepoutend)) {
 119                 /* Access the valid portion before the keepout. */
 120                 if (offset < keepout->start) {
 121                         kend = min(end, keepout->start);
 122                         ksize = kend - offset;
 123                         if (write)
 124                                 rc = __nvmem_reg_write(nvmem, offset, val, ksize);
 125                         else
 126                                 rc = __nvmem_reg_read(nvmem, offset, val, ksize);
 127
 128                         if (rc)
 129                                 return rc;
 130
 131                         offset += ksize;
 132                         val += ksize;
 133                 }
 134
 135                 /*
 136                  * Now we're aligned to the start of this keepout zone. Go
 137                  * through it.
 138                  */
 139                 kend = min(end, keepout->end);
 140                 ksize = kend - offset;
 141                 if (!write)
 142                         memset(val, keepout->value, ksize);
 143
 144                 val += ksize;
 145                 offset += ksize;
 146                 keepout++;
 147         }
 148
 149         /*
 150          * If we ran out of keepouts but there's still stuff to do, send it
 151          * down directly
 152          */
 153         if (offset < end) {
 154                 ksize = end - offset;
 155                 if (write)
 156                         return __nvmem_reg_write(nvmem, offset, val, ksize);
 157                 else
 158                         return __nvmem_reg_read(nvmem, offset, val, ksize);
 159         }
 160
 161         return 0;
 162 }
 163
 164 static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
 165                           void *val, size_t bytes)
 166 {
 167         if (!nvmem->nkeepout)
 168                 return __nvmem_reg_read(nvmem, offset, val, bytes);
 169
 170         return nvmem_access_with_keepouts(nvmem, offset, val, bytes, false);
 171 }
 172
 173 static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
 174                            void *val, size_t bytes)
 175 {
 176         if (!nvmem->nkeepout)
 177                 return __nvmem_reg_write(nvmem, offset, val, bytes);
 178
 179         return nvmem_access_with_keepouts(nvmem, offset, val, bytes, true);
 180 }
 181
 182 #ifdef CONFIG_NVMEM_SYSFS
 183 static const char * const nvmem_type_str[] = {
 184         [NVMEM_TYPE_UNKNOWN] = "Unknown",
 185         [NVMEM_TYPE_EEPROM] = "EEPROM",
 186         [NVMEM_TYPE_OTP] = "OTP",
 187         [NVMEM_TYPE_BATTERY_BACKED] = "Battery backed",
 188         [NVMEM_TYPE_FRAM] = "FRAM",
 189 };
 190
 191 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 192 static struct lock_class_key eeprom_lock_key;
 193 #endif
 194
 195 static ssize_t type_show(struct device *dev,
 196                          struct device_attribute *attr, char *buf)
 197 {
 198         struct nvmem_device *nvmem = to_nvmem_device(dev);
 199
 200         return sprintf(buf, "%s\n", nvmem_type_str[nvmem->type]);
 201 }
 202
 203 static DEVICE_ATTR_RO(type);
 204
 205 static struct attribute *nvmem_attrs[] = {
 206         &dev_attr_type.attr,
 207         NULL,
 208 };
 209
 210 static ssize_t bin_attr_nvmem_read(struct file *filp, struct kobject *kobj,
 211                                    struct bin_attribute *attr, char *buf,
 212                                    loff_t pos, size_t count)
 213 {
 214         struct device *dev;
 215         struct nvmem_device *nvmem;
 216         int rc;
 217
 218         if (attr->private)
 219                 dev = attr->private;
 220         else
 221                 dev = kobj_to_dev(kobj);
 222         nvmem = to_nvmem_device(dev);
 223
 224         /* Stop the user from reading */
 225         if (pos >= nvmem->size)
 226                 return 0;
 227
 228         if (!IS_ALIGNED(pos, nvmem->stride))
 229                 return -EINVAL;
 230
 231         if (count < nvmem->word_size)
 232                 return -EINVAL;
 233
 234         if (pos + count > nvmem->size)
 235                 count = nvmem->size - pos;
 236
 237         count = round_down(count, nvmem->word_size);
 238
 239         if (!nvmem->reg_read)
 240                 return -EPERM;
 241
 242         rc = nvmem_reg_read(nvmem, pos, buf, count);
 243
 244         if (rc)
 245                 return rc;
 246
 247         return count;
 248 }
 249
 250 static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj,
 251                                     struct bin_attribute *attr, char *buf,
 252                                     loff_t pos, size_t count)
 253 {
 254         struct device *dev;
 255         struct nvmem_device *nvmem;
 256         int rc;
 257
 258         if (attr->private)
 259                 dev = attr->private;
 260         else
 261                 dev = kobj_to_dev(kobj);
 262         nvmem = to_nvmem_device(dev);
 263
 264         /* Stop the user from writing */
 265         if (pos >= nvmem->size)
 266                 return -EFBIG;
 267
 268         if (!IS_ALIGNED(pos, nvmem->stride))
 269                 return -EINVAL;
 270
 271         if (count < nvmem->word_size)
 272                 return -EINVAL;
 273
 274         if (pos + count > nvmem->size)
 275                 count = nvmem->size - pos;
 276
 277         count = round_down(count, nvmem->word_size);
 278
 279         if (!nvmem->reg_write)
 280                 return -EPERM;
 281
 282         rc = nvmem_reg_write(nvmem, pos, buf, count);
 283
 284         if (rc)
 285                 return rc;
 286
 287         return count;
 288 }
 289
 290 static umode_t nvmem_bin_attr_get_umode(struct nvmem_device *nvmem)
 291 {
 292         umode_t mode = 0400;
 293
 294         if (!nvmem->root_only)
 295                 mode |= 0044;
 296
 297         if (!nvmem->read_only)
 298                 mode |= 0200;
 299
 300         if (!nvmem->reg_write)
 301                 mode &= ~0200;
 302
 303         if (!nvmem->reg_read)
 304                 mode &= ~0444;
 305
 306         return mode;
 307 }
 308
 309 static umode_t nvmem_bin_attr_is_visible(struct kobject *kobj,
 310                                          struct bin_attribute *attr, int i)
 311 {
 312         struct device *dev = kobj_to_dev(kobj);
 313         struct nvmem_device *nvmem = to_nvmem_device(dev);
 314
 315         attr->size = nvmem->size;
 316
 317         return nvmem_bin_attr_get_umode(nvmem);
 318 }
 319
 320 /* default read/write permissions */
 321 static struct bin_attribute bin_attr_rw_nvmem = {
 322         .attr   = {
 323                 .name   = "nvmem",
 324                 .mode   = 0644,
 325         },
 326         .read   = bin_attr_nvmem_read,
 327         .write  = bin_attr_nvmem_write,
 328 };
 329
 330 static struct bin_attribute *nvmem_bin_attributes[] = {
 331         &bin_attr_rw_nvmem,
 332         NULL,
 333 };
 334
 335 static const struct attribute_group nvmem_bin_group = {
 336         .bin_attrs      = nvmem_bin_attributes,
 337         .attrs          = nvmem_attrs,
 338         .is_bin_visible = nvmem_bin_attr_is_visible,
 339 };
 340
 341 static const struct attribute_group *nvmem_dev_groups[] = {
 342         &nvmem_bin_group,
 343         NULL,
 344 };
 345
 346 static struct bin_attribute bin_attr_nvmem_eeprom_compat = {
 347         .attr   = {
 348                 .name   = "eeprom",
 349         },
 350         .read   = bin_attr_nvmem_read,
 351         .write  = bin_attr_nvmem_write,
 352 };
 353
 354 /*
 355  * nvmem_setup_compat() - Create an additional binary entry in
 356  * drivers sys directory, to be backwards compatible with the older
 357  * drivers/misc/eeprom drivers.
 358  */
 359 static int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
 360                                     const struct nvmem_config *config)
 361 {
 362         int rval;
 363
 364         if (!config->compat)
 365                 return 0;
 366
 367         if (!config->base_dev)
 368                 return -EINVAL;
 369
 370         if (config->type == NVMEM_TYPE_FRAM)
 371                 bin_attr_nvmem_eeprom_compat.attr.name = "fram";
 372
 373         nvmem->eeprom = bin_attr_nvmem_eeprom_compat;
 374         nvmem->eeprom.attr.mode = nvmem_bin_attr_get_umode(nvmem);
 375         nvmem->eeprom.size = nvmem->size;
 376 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 377         nvmem->eeprom.attr.key = &eeprom_lock_key;
 378 #endif
 379         nvmem->eeprom.private = &nvmem->dev;
 380         nvmem->base_dev = config->base_dev;
 381
 382         rval = device_create_bin_file(nvmem->base_dev, &nvmem->eeprom);
 383         if (rval) {
 384                 dev_err(&nvmem->dev,
 385                         "Failed to create eeprom binary file %d\n", rval);
 386                 return rval;
 387         }
 388
 389         nvmem->flags |= FLAG_COMPAT;
 390
 391         return 0;
 392 }
 393
 394 static void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem,
 395                               const struct nvmem_config *config)
 396 {
 397         if (config->compat)
 398                 device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
 399 }
 400
 401 #else /* CONFIG_NVMEM_SYSFS */
 402
 403 static int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
 404                                     const struct nvmem_config *config)
 405 {
 406         return -ENOSYS;
 407 }
 408 static void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem,
 409                                       const struct nvmem_config *config)
 410 {
 411 }
 412
 413 #endif /* CONFIG_NVMEM_SYSFS */
 414
 415 static void nvmem_release(struct device *dev)
 416 {
 417         struct nvmem_device *nvmem = to_nvmem_device(dev);
 418
 419         ida_free(&nvmem_ida, nvmem->id);
 420         gpiod_put(nvmem->wp_gpio);
 421         kfree(nvmem);
 422 }
 423
 424 static const struct device_type nvmem_provider_type = {
 425         .release        = nvmem_release,
 426 };
 427
 428 static struct bus_type nvmem_bus_type = {
 429         .name           = "nvmem",
 430 };
 431
 432 static void nvmem_cell_entry_drop(struct nvmem_cell_entry *cell)
 433 {
 434         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_REMOVE, cell);
 435         mutex_lock(&nvmem_mutex);
 436         list_del(&cell->node);
 437         mutex_unlock(&nvmem_mutex);
 438         of_node_put(cell->np);
 439         kfree_const(cell->name);
 440         kfree(cell);
 441 }
 442
 443 static void nvmem_device_remove_all_cells(const struct nvmem_device *nvmem)
 444 {
 445         struct nvmem_cell_entry *cell, *p;
 446
 447         list_for_each_entry_safe(cell, p, &nvmem->cells, node)
 448                 nvmem_cell_entry_drop(cell);
 449 }
 450
 451 static void nvmem_cell_entry_add(struct nvmem_cell_entry *cell)
 452 {
 453         mutex_lock(&nvmem_mutex);
 454         list_add_tail(&cell->node, &cell->nvmem->cells);
 455         mutex_unlock(&nvmem_mutex);
 456         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_ADD, cell);
 457 }
 458
 459 static int nvmem_cell_info_to_nvmem_cell_entry_nodup(struct nvmem_device *nvmem,
 460                                                      const struct nvmem_cell_info *info,
 461                                                      struct nvmem_cell_entry *cell)
 462 {
 463         cell->nvmem = nvmem;
 464         cell->offset = info->offset;
 465         cell->bytes = info->bytes;
 466         cell->name = info->name;
 467
 468         cell->bit_offset = info->bit_offset;
 469         cell->nbits = info->nbits;
 470         cell->np = info->np;
 471
 472         if (cell->nbits)
 473                 cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
 474                                            BITS_PER_BYTE);
 475
 476         if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
 477                 dev_err(&nvmem->dev,
 478                         "cell %s unaligned to nvmem stride %d\n",
 479                         cell->name ?: "<unknown>", nvmem->stride);
 480                 return -EINVAL;
 481         }
 482
 483         return 0;
 484 }
 485
 486 static int nvmem_cell_info_to_nvmem_cell_entry(struct nvmem_device *nvmem,
 487                                                const struct nvmem_cell_info *info,
 488                                                struct nvmem_cell_entry *cell)
 489 {
 490         int err;
 491
 492         err = nvmem_cell_info_to_nvmem_cell_entry_nodup(nvmem, info, cell);
 493         if (err)
 494                 return err;
 495
 496         cell->name = kstrdup_const(info->name, GFP_KERNEL);
 497         if (!cell->name)
 498                 return -ENOMEM;
 499
 500         return 0;
 501 }
 502
 503 /**
 504  * nvmem_add_cells() - Add cell information to an nvmem device
 505  *
 506  * @nvmem: nvmem device to add cells to.
 507  * @info: nvmem cell info to add to the device
 508  * @ncells: number of cells in info
 509  *
 510  * Return: 0 or negative error code on failure.
 511  */
 512 static int nvmem_add_cells(struct nvmem_device *nvmem,
 513                     const struct nvmem_cell_info *info,
 514                     int ncells)
 515 {
 516         struct nvmem_cell_entry **cells;
 517         int i, rval;
 518
 519         cells = kcalloc(ncells, sizeof(*cells), GFP_KERNEL);
 520         if (!cells)
 521                 return -ENOMEM;
 522
 523         for (i = 0; i < ncells; i++) {
 524                 cells[i] = kzalloc(sizeof(**cells), GFP_KERNEL);
 525                 if (!cells[i]) {
 526                         rval = -ENOMEM;
 527                         goto err;
 528                 }
 529
 530                 rval = nvmem_cell_info_to_nvmem_cell_entry(nvmem, &info[i], cells[i]);
 531                 if (rval) {
 532                         kfree(cells[i]);
 533                         goto err;
 534                 }
 535
 536                 nvmem_cell_entry_add(cells[i]);
 537         }
 538
 539         /* remove tmp array */
 540         kfree(cells);
 541
 542         return 0;
 543 err:
 544         while (i--)
 545                 nvmem_cell_entry_drop(cells[i]);
 546
 547         kfree(cells);
 548
 549         return rval;
 550 }
 551
 552 /**
 553  * nvmem_register_notifier() - Register a notifier block for nvmem events.
 554  *
 555  * @nb: notifier block to be called on nvmem events.
 556  *
 557  * Return: 0 on success, negative error number on failure.
 558  */
 559 int nvmem_register_notifier(struct notifier_block *nb)
 560 {
 561         return blocking_notifier_chain_register(&nvmem_notifier, nb);
 562 }
 563 EXPORT_SYMBOL_GPL(nvmem_register_notifier);
 564
 565 /**
 566  * nvmem_unregister_notifier() - Unregister a notifier block for nvmem events.
 567  *
 568  * @nb: notifier block to be unregistered.
 569  *
 570  * Return: 0 on success, negative error number on failure.
 571  */
 572 int nvmem_unregister_notifier(struct notifier_block *nb)
 573 {
 574         return blocking_notifier_chain_unregister(&nvmem_notifier, nb);
 575 }
 576 EXPORT_SYMBOL_GPL(nvmem_unregister_notifier);
 577
 578 static int nvmem_add_cells_from_table(struct nvmem_device *nvmem)
 579 {
 580         const struct nvmem_cell_info *info;
 581         struct nvmem_cell_table *table;
 582         struct nvmem_cell_entry *cell;
 583         int rval = 0, i;
 584
 585         mutex_lock(&nvmem_cell_mutex);
 586         list_for_each_entry(table, &nvmem_cell_tables, node) {
 587                 if (strcmp(nvmem_dev_name(nvmem), table->nvmem_name) == 0) {
 588                         for (i = 0; i < table->ncells; i++) {
 589                                 info = &table->cells[i];
 590
 591                                 cell = kzalloc(sizeof(*cell), GFP_KERNEL);
 592                                 if (!cell) {
 593                                         rval = -ENOMEM;
 594                                         goto out;
 595                                 }
 596
 597                                 rval = nvmem_cell_info_to_nvmem_cell_entry(nvmem, info, cell);
 598                                 if (rval) {
 599                                         kfree(cell);
 600                                         goto out;
 601                                 }
 602
 603                                 nvmem_cell_entry_add(cell);
 604                         }
 605                 }
 606         }
 607
 608 out:
 609         mutex_unlock(&nvmem_cell_mutex);
 610         return rval;
 611 }
 612
 613 static struct nvmem_cell_entry *
 614 nvmem_find_cell_entry_by_name(struct nvmem_device *nvmem, const char *cell_id)
 615 {
 616         struct nvmem_cell_entry *iter, *cell = NULL;
 617
 618         mutex_lock(&nvmem_mutex);
 619         list_for_each_entry(iter, &nvmem->cells, node) {
 620                 if (strcmp(cell_id, iter->name) == 0) {
 621                         cell = iter;
 622                         break;
 623                 }
 624         }
 625         mutex_unlock(&nvmem_mutex);
 626
 627         return cell;
 628 }
 629
 630 static int nvmem_validate_keepouts(struct nvmem_device *nvmem)
 631 {
 632         unsigned int cur = 0;
 633         const struct nvmem_keepout *keepout = nvmem->keepout;
 634         const struct nvmem_keepout *keepoutend = keepout + nvmem->nkeepout;
 635
 636         while (keepout < keepoutend) {
 637                 /* Ensure keepouts are sorted and don't overlap. */
 638                 if (keepout->start < cur) {
 639                         dev_err(&nvmem->dev,
 640                                 "Keepout regions aren't sorted or overlap.\n");
 641
 642                         return -ERANGE;
 643                 }
 644
 645                 if (keepout->end < keepout->start) {
 646                         dev_err(&nvmem->dev,
 647                                 "Invalid keepout region.\n");
 648
 649                         return -EINVAL;
 650                 }
 651
 652                 /*
 653                  * Validate keepouts (and holes between) don't violate
 654                  * word_size constraints.
 655                  */
 656                 if ((keepout->end - keepout->start < nvmem->word_size) ||
 657                     ((keepout->start != cur) &&
 658                      (keepout->start - cur < nvmem->word_size))) {
 659
 660                         dev_err(&nvmem->dev,
 661                                 "Keepout regions violate word_size constraints.\n");
 662
 663                         return -ERANGE;
 664                 }
 665
 666                 /* Validate keepouts don't violate stride (alignment). */
 667                 if (!IS_ALIGNED(keepout->start, nvmem->stride) ||
 668                     !IS_ALIGNED(keepout->end, nvmem->stride)) {
 669
 670                         dev_err(&nvmem->dev,
 671                                 "Keepout regions violate stride.\n");
 672
 673                         return -EINVAL;
 674                 }
 675
 676                 cur = keepout->end;
 677                 keepout++;
 678         }
 679
 680         return 0;
 681 }
 682
 683 static int nvmem_add_cells_from_of(struct nvmem_device *nvmem)
 684 {
 685         struct device_node *parent, *child;
 686         struct device *dev = &nvmem->dev;
 687         struct nvmem_cell_entry *cell;
 688         const __be32 *addr;
 689         int len;
 690
 691         parent = dev->of_node;
 692
 693         for_each_child_of_node(parent, child) {
 694                 addr = of_get_property(child, "reg", &len);
 695                 if (!addr)
 696                         continue;
 697                 if (len < 2 * sizeof(u32)) {
 698                         dev_err(dev, "nvmem: invalid reg on %pOF\n", child);
 699                         of_node_put(child);
 700                         return -EINVAL;
 701                 }
 702
 703                 cell = kzalloc(sizeof(*cell), GFP_KERNEL);
 704                 if (!cell) {
 705                         of_node_put(child);
 706                         return -ENOMEM;
 707                 }
 708
 709                 cell->nvmem = nvmem;
 710                 cell->offset = be32_to_cpup(addr++);
 711                 cell->bytes = be32_to_cpup(addr);
 712                 cell->name = kasprintf(GFP_KERNEL, "%pOFn", child);
 713
 714                 addr = of_get_property(child, "bits", &len);
 715                 if (addr && len == (2 * sizeof(u32))) {
 716                         cell->bit_offset = be32_to_cpup(addr++);
 717                         cell->nbits = be32_to_cpup(addr);
 718                 }
 719
 720                 if (cell->nbits)
 721                         cell->bytes = DIV_ROUND_UP(
 722                                         cell->nbits + cell->bit_offset,
 723                                         BITS_PER_BYTE);
 724
 725                 if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
 726                         dev_err(dev, "cell %s unaligned to nvmem stride %d\n",
 727                                 cell->name, nvmem->stride);
 728                         /* Cells already added will be freed later. */
 729                         kfree_const(cell->name);
 730                         kfree(cell);
 731                         of_node_put(child);
 732                         return -EINVAL;
 733                 }
 734
 735                 cell->np = of_node_get(child);
 736                 nvmem_cell_entry_add(cell);
 737         }
 738
 739         return 0;
 740 }
 741
 742 /**
 743  * nvmem_register() - Register a nvmem device for given nvmem_config.
 744  * Also creates a binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
 745  *
 746  * @config: nvmem device configuration with which nvmem device is created.
 747  *
 748  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
 749  * on success.
 750  */
 751
 752 struct nvmem_device *nvmem_register(const struct nvmem_config *config)
 753 {
 754         struct nvmem_device *nvmem;
 755         int rval;
 756
 757         if (!config->dev)
 758                 return ERR_PTR(-EINVAL);
 759
 760         if (!config->reg_read && !config->reg_write)
 761                 return ERR_PTR(-EINVAL);
 762
 763         nvmem = kzalloc(sizeof(*nvmem), GFP_KERNEL);
 764         if (!nvmem)
 765                 return ERR_PTR(-ENOMEM);
 766
 767         rval  = ida_alloc(&nvmem_ida, GFP_KERNEL);
 768         if (rval < 0) {
 769                 kfree(nvmem);
 770                 return ERR_PTR(rval);
 771         }
 772
 773         if (config->wp_gpio)
 774                 nvmem->wp_gpio = config->wp_gpio;
 775         else if (!config->ignore_wp)
 776                 nvmem->wp_gpio = gpiod_get_optional(config->dev, "wp",
 777                                                     GPIOD_OUT_HIGH);
 778         if (IS_ERR(nvmem->wp_gpio)) {
 779                 ida_free(&nvmem_ida, nvmem->id);
 780                 rval = PTR_ERR(nvmem->wp_gpio);
 781                 kfree(nvmem);
 782                 return ERR_PTR(rval);
 783         }
 784
 785         kref_init(&nvmem->refcnt);
 786         INIT_LIST_HEAD(&nvmem->cells);
 787
 788         nvmem->id = rval;
 789         nvmem->owner = config->owner;
 790         if (!nvmem->owner && config->dev->driver)
 791                 nvmem->owner = config->dev->driver->owner;
 792         nvmem->stride = config->stride ?: 1;
 793         nvmem->word_size = config->word_size ?: 1;
 794         nvmem->size = config->size;
 795         nvmem->dev.type = &nvmem_provider_type;
 796         nvmem->dev.bus = &nvmem_bus_type;
 797         nvmem->dev.parent = config->dev;
 798         nvmem->root_only = config->root_only;
 799         nvmem->priv = config->priv;
 800         nvmem->type = config->type;
 801         nvmem->reg_read = config->reg_read;
 802         nvmem->reg_write = config->reg_write;
 803         nvmem->cell_post_process = config->cell_post_process;
 804         nvmem->keepout = config->keepout;
 805         nvmem->nkeepout = config->nkeepout;
 806         if (config->of_node)
 807                 nvmem->dev.of_node = config->of_node;
 808         else if (!config->no_of_node)
 809                 nvmem->dev.of_node = config->dev->of_node;
 810
 811         switch (config->id) {
 812         case NVMEM_DEVID_NONE:
 813                 rval = dev_set_name(&nvmem->dev, "%s", config->name);
 814                 break;
 815         case NVMEM_DEVID_AUTO:
 816                 rval = dev_set_name(&nvmem->dev, "%s%d", config->name, nvmem->id);
 817                 break;
 818         default:
 819                 rval = dev_set_name(&nvmem->dev, "%s%d",
 820                              config->name ? : "nvmem",
 821                              config->name ? config->id : nvmem->id);
 822                 break;
 823         }
 824
 825         if (rval) {
 826                 ida_free(&nvmem_ida, nvmem->id);
 827                 kfree(nvmem);
 828                 return ERR_PTR(rval);
 829         }
 830
 831         nvmem->read_only = device_property_present(config->dev, "read-only") ||
 832                            config->read_only || !nvmem->reg_write;
 833
 834 #ifdef CONFIG_NVMEM_SYSFS
 835         nvmem->dev.groups = nvmem_dev_groups;
 836 #endif
 837
 838         dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
 839
 840         rval = device_register(&nvmem->dev);
 841         if (rval)
 842                 goto err_put_device;
 843
 844         if (nvmem->nkeepout) {
 845                 rval = nvmem_validate_keepouts(nvmem);
 846                 if (rval)
 847                         goto err_device_del;
 848         }
 849
 850         if (config->compat) {
 851                 rval = nvmem_sysfs_setup_compat(nvmem, config);
 852                 if (rval)
 853                         goto err_device_del;
 854         }
 855
 856         if (config->cells) {
 857                 rval = nvmem_add_cells(nvmem, config->cells, config->ncells);
 858                 if (rval)
 859                         goto err_teardown_compat;
 860         }
 861
 862         rval = nvmem_add_cells_from_table(nvmem);
 863         if (rval)
 864                 goto err_remove_cells;
 865
 866         rval = nvmem_add_cells_from_of(nvmem);
 867         if (rval)
 868                 goto err_remove_cells;
 869
 870         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem);
 871
 872         return nvmem;
 873
 874 err_remove_cells:
 875         nvmem_device_remove_all_cells(nvmem);
 876 err_teardown_compat:
 877         if (config->compat)
 878                 nvmem_sysfs_remove_compat(nvmem, config);
 879 err_device_del:
 880         device_del(&nvmem->dev);
 881 err_put_device:
 882         put_device(&nvmem->dev);
 883
 884         return ERR_PTR(rval);
 885 }
 886 EXPORT_SYMBOL_GPL(nvmem_register);
 887
 888 static void nvmem_device_release(struct kref *kref)
 889 {
 890         struct nvmem_device *nvmem;
 891
 892         nvmem = container_of(kref, struct nvmem_device, refcnt);
 893
 894         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_REMOVE, nvmem);
 895
 896         if (nvmem->flags & FLAG_COMPAT)
 897                 device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
 898
 899         nvmem_device_remove_all_cells(nvmem);
 900         device_unregister(&nvmem->dev);
 901 }
 902
 903 /**
 904  * nvmem_unregister() - Unregister previously registered nvmem device
 905  *
 906  * @nvmem: Pointer to previously registered nvmem device.
 907  */
 908 void nvmem_unregister(struct nvmem_device *nvmem)
 909 {
 910         if (nvmem)
 911                 kref_put(&nvmem->refcnt, nvmem_device_release);
 912 }
 913 EXPORT_SYMBOL_GPL(nvmem_unregister);
 914
 915 static void devm_nvmem_unregister(void *nvmem)
 916 {
 917         nvmem_unregister(nvmem);
 918 }
 919
 920 /**
 921  * devm_nvmem_register() - Register a managed nvmem device for given
 922  * nvmem_config.
 923  * Also creates a binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
 924  *
 925  * @dev: Device that uses the nvmem device.
 926  * @config: nvmem device configuration with which nvmem device is created.
 927  *
 928  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
 929  * on success.
 930  */
 931 struct nvmem_device *devm_nvmem_register(struct device *dev,
 932                                          const struct nvmem_config *config)
 933 {
 934         struct nvmem_device *nvmem;
 935         int ret;
 936
 937         nvmem = nvmem_register(config);
 938         if (IS_ERR(nvmem))
 939                 return nvmem;
 940
 941         ret = devm_add_action_or_reset(dev, devm_nvmem_unregister, nvmem);
 942         if (ret)
 943                 return ERR_PTR(ret);
 944
 945         return nvmem;
 946 }
 947 EXPORT_SYMBOL_GPL(devm_nvmem_register);
 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 *nvmem_create_cell(struct nvmem_cell_entry *entry, const char *id)
1131 {
1132         struct nvmem_cell *cell;
1133         const char *name = NULL;
1134
1135         cell = kzalloc(sizeof(*cell), GFP_KERNEL);
1136         if (!cell)
1137                 return ERR_PTR(-ENOMEM);
1138
1139         if (id) {
1140                 name = kstrdup_const(id, GFP_KERNEL);
1141                 if (!name) {
1142                         kfree(cell);
1143                         return ERR_PTR(-ENOMEM);
1144                 }
1145         }
1146
1147         cell->id = name;
1148         cell->entry = entry;
1149
1150         return cell;
1151 }
1152
1153 static struct nvmem_cell *
1154 nvmem_cell_get_from_lookup(struct device *dev, const char *con_id)
1155 {
1156         struct nvmem_cell_entry *cell_entry;
1157         struct nvmem_cell *cell = ERR_PTR(-ENOENT);
1158         struct nvmem_cell_lookup *lookup;
1159         struct nvmem_device *nvmem;
1160         const char *dev_id;
1161
1162         if (!dev)
1163                 return ERR_PTR(-EINVAL);
1164
1165         dev_id = dev_name(dev);
1166
1167         mutex_lock(&nvmem_lookup_mutex);
1168
1169         list_for_each_entry(lookup, &nvmem_lookup_list, node) {
1170                 if ((strcmp(lookup->dev_id, dev_id) == 0) &&
1171                     (strcmp(lookup->con_id, con_id) == 0)) {
1172                         /* This is the right entry. */
1173                         nvmem = __nvmem_device_get((void *)lookup->nvmem_name,
1174                                                    device_match_name);
1175                         if (IS_ERR(nvmem)) {
1176                                 /* Provider may not be registered yet. */
1177                                 cell = ERR_CAST(nvmem);
1178                                 break;
1179                         }
1180
1181                         cell_entry = nvmem_find_cell_entry_by_name(nvmem,
1182                                                                    lookup->cell_name);
1183                         if (!cell_entry) {
1184                                 __nvmem_device_put(nvmem);
1185                                 cell = ERR_PTR(-ENOENT);
1186                         } else {
1187                                 cell = nvmem_create_cell(cell_entry, con_id);
1188                                 if (IS_ERR(cell))
1189                                         __nvmem_device_put(nvmem);
1190                         }
1191                         break;
1192                 }
1193         }
1194
1195         mutex_unlock(&nvmem_lookup_mutex);
1196         return cell;
1197 }
1198
1199 #if IS_ENABLED(CONFIG_OF)
1200 static struct nvmem_cell_entry *
1201 nvmem_find_cell_entry_by_node(struct nvmem_device *nvmem, struct device_node *np)
1202 {
1203         struct nvmem_cell_entry *iter, *cell = NULL;
1204
1205         mutex_lock(&nvmem_mutex);
1206         list_for_each_entry(iter, &nvmem->cells, node) {
1207                 if (np == iter->np) {
1208                         cell = iter;
1209                         break;
1210                 }
1211         }
1212         mutex_unlock(&nvmem_mutex);
1213
1214         return cell;
1215 }
1216
1217 /**
1218  * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
1219  *
1220  * @np: Device tree node that uses the nvmem cell.
1221  * @id: nvmem cell name from nvmem-cell-names property, or NULL
1222  *      for the cell at index 0 (the lone cell with no accompanying
1223  *      nvmem-cell-names property).
1224  *
1225  * Return: Will be an ERR_PTR() on error or a valid pointer
1226  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1227  * nvmem_cell_put().
1228  */
1229 struct nvmem_cell *of_nvmem_cell_get(struct device_node *np, const char *id)
1230 {
1231         struct device_node *cell_np, *nvmem_np;
1232         struct nvmem_device *nvmem;
1233         struct nvmem_cell_entry *cell_entry;
1234         struct nvmem_cell *cell;
1235         int index = 0;
1236
1237         /* if cell name exists, find index to the name */
1238         if (id)
1239                 index = of_property_match_string(np, "nvmem-cell-names", id);
1240
1241         cell_np = of_parse_phandle(np, "nvmem-cells", index);
1242         if (!cell_np)
1243                 return ERR_PTR(-ENOENT);
1244
1245         nvmem_np = of_get_next_parent(cell_np);
1246         if (!nvmem_np)
1247                 return ERR_PTR(-EINVAL);
1248
1249         nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
1250         of_node_put(nvmem_np);
1251         if (IS_ERR(nvmem))
1252                 return ERR_CAST(nvmem);
1253
1254         cell_entry = nvmem_find_cell_entry_by_node(nvmem, cell_np);
1255         if (!cell_entry) {
1256                 __nvmem_device_put(nvmem);
1257                 return ERR_PTR(-ENOENT);
1258         }
1259
1260         cell = nvmem_create_cell(cell_entry, id);
1261         if (IS_ERR(cell))
1262                 __nvmem_device_put(nvmem);
1263
1264         return cell;
1265 }
1266 EXPORT_SYMBOL_GPL(of_nvmem_cell_get);
1267 #endif
1268
1269 /**
1270  * nvmem_cell_get() - Get nvmem cell of device form a given cell name
1271  *
1272  * @dev: Device that requests the nvmem cell.
1273  * @id: nvmem cell name to get (this corresponds with the name from the
1274  *      nvmem-cell-names property for DT systems and with the con_id from
1275  *      the lookup entry for non-DT systems).
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  * nvmem_cell_put().
1280  */
1281 struct nvmem_cell *nvmem_cell_get(struct device *dev, const char *id)
1282 {
1283         struct nvmem_cell *cell;
1284
1285         if (dev->of_node) { /* try dt first */
1286                 cell = of_nvmem_cell_get(dev->of_node, id);
1287                 if (!IS_ERR(cell) || PTR_ERR(cell) == -EPROBE_DEFER)
1288                         return cell;
1289         }
1290
1291         /* NULL cell id only allowed for device tree; invalid otherwise */
1292         if (!id)
1293                 return ERR_PTR(-EINVAL);
1294
1295         return nvmem_cell_get_from_lookup(dev, id);
1296 }
1297 EXPORT_SYMBOL_GPL(nvmem_cell_get);
1298
1299 static void devm_nvmem_cell_release(struct device *dev, void *res)
1300 {
1301         nvmem_cell_put(*(struct nvmem_cell **)res);
1302 }
1303
1304 /**
1305  * devm_nvmem_cell_get() - Get nvmem cell of device form a given id
1306  *
1307  * @dev: Device that requests the nvmem cell.
1308  * @id: nvmem cell name id to get.
1309  *
1310  * Return: Will be an ERR_PTR() on error or a valid pointer
1311  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1312  * automatically once the device is freed.
1313  */
1314 struct nvmem_cell *devm_nvmem_cell_get(struct device *dev, const char *id)
1315 {
1316         struct nvmem_cell **ptr, *cell;
1317
1318         ptr = devres_alloc(devm_nvmem_cell_release, sizeof(*ptr), GFP_KERNEL);
1319         if (!ptr)
1320                 return ERR_PTR(-ENOMEM);
1321
1322         cell = nvmem_cell_get(dev, id);
1323         if (!IS_ERR(cell)) {
1324                 *ptr = cell;
1325                 devres_add(dev, ptr);
1326         } else {
1327                 devres_free(ptr);
1328         }
1329
1330         return cell;
1331 }
1332 EXPORT_SYMBOL_GPL(devm_nvmem_cell_get);
1333
1334 static int devm_nvmem_cell_match(struct device *dev, void *res, void *data)
1335 {
1336         struct nvmem_cell **c = res;
1337
1338         if (WARN_ON(!c || !*c))
1339                 return 0;
1340
1341         return *c == data;
1342 }
1343
1344 /**
1345  * devm_nvmem_cell_put() - Release previously allocated nvmem cell
1346  * from devm_nvmem_cell_get.
1347  *
1348  * @dev: Device that requests the nvmem cell.
1349  * @cell: Previously allocated nvmem cell by devm_nvmem_cell_get().
1350  */
1351 void devm_nvmem_cell_put(struct device *dev, struct nvmem_cell *cell)
1352 {
1353         int ret;
1354
1355         ret = devres_release(dev, devm_nvmem_cell_release,
1356                                 devm_nvmem_cell_match, cell);
1357
1358         WARN_ON(ret);
1359 }
1360 EXPORT_SYMBOL(devm_nvmem_cell_put);
1361
1362 /**
1363  * nvmem_cell_put() - Release previously allocated nvmem cell.
1364  *
1365  * @cell: Previously allocated nvmem cell by nvmem_cell_get().
1366  */
1367 void nvmem_cell_put(struct nvmem_cell *cell)
1368 {
1369         struct nvmem_device *nvmem = cell->entry->nvmem;
1370
1371         if (cell->id)
1372                 kfree_const(cell->id);
1373
1374         kfree(cell);
1375         __nvmem_device_put(nvmem);
1376 }
1377 EXPORT_SYMBOL_GPL(nvmem_cell_put);
1378
1379 static void nvmem_shift_read_buffer_in_place(struct nvmem_cell_entry *cell, void *buf)
1380 {
1381         u8 *p, *b;
1382         int i, extra, bit_offset = cell->bit_offset;
1383
1384         p = b = buf;
1385         if (bit_offset) {
1386                 /* First shift */
1387                 *b++ >>= bit_offset;
1388
1389                 /* setup rest of the bytes if any */
1390                 for (i = 1; i < cell->bytes; i++) {
1391                         /* Get bits from next byte and shift them towards msb */
1392                         *p |= *b << (BITS_PER_BYTE - bit_offset);
1393
1394                         p = b;
1395                         *b++ >>= bit_offset;
1396                 }
1397         } else {
1398                 /* point to the msb */
1399                 p += cell->bytes - 1;
1400         }
1401
1402         /* result fits in less bytes */
1403         extra = cell->bytes - DIV_ROUND_UP(cell->nbits, BITS_PER_BYTE);
1404         while (--extra >= 0)
1405                 *p-- = 0;
1406
1407         /* clear msb bits if any leftover in the last byte */
1408         if (cell->nbits % BITS_PER_BYTE)
1409                 *p &= GENMASK((cell->nbits % BITS_PER_BYTE) - 1, 0);
1410 }
1411
1412 static int __nvmem_cell_read(struct nvmem_device *nvmem,
1413                       struct nvmem_cell_entry *cell,
1414                       void *buf, size_t *len, const char *id)
1415 {
1416         int rc;
1417
1418         rc = nvmem_reg_read(nvmem, cell->offset, buf, cell->bytes);
1419
1420         if (rc)
1421                 return rc;
1422
1423         /* shift bits in-place */
1424         if (cell->bit_offset || cell->nbits)
1425                 nvmem_shift_read_buffer_in_place(cell, buf);
1426
1427         if (nvmem->cell_post_process) {
1428                 rc = nvmem->cell_post_process(nvmem->priv, id,
1429                                               cell->offset, buf, cell->bytes);
1430                 if (rc)
1431                         return rc;
1432         }
1433
1434         if (len)
1435                 *len = cell->bytes;
1436
1437         return 0;
1438 }
1439
1440 /**
1441  * nvmem_cell_read() - Read a given nvmem cell
1442  *
1443  * @cell: nvmem cell to be read.
1444  * @len: pointer to length of cell which will be populated on successful read;
1445  *       can be NULL.
1446  *
1447  * Return: ERR_PTR() on error or a valid pointer to a buffer on success. The
1448  * buffer should be freed by the consumer with a kfree().
1449  */
1450 void *nvmem_cell_read(struct nvmem_cell *cell, size_t *len)
1451 {
1452         struct nvmem_device *nvmem = cell->entry->nvmem;
1453         u8 *buf;
1454         int rc;
1455
1456         if (!nvmem)
1457                 return ERR_PTR(-EINVAL);
1458
1459         buf = kzalloc(cell->entry->bytes, GFP_KERNEL);
1460         if (!buf)
1461                 return ERR_PTR(-ENOMEM);
1462
1463         rc = __nvmem_cell_read(nvmem, cell->entry, buf, len, cell->id);
1464         if (rc) {
1465                 kfree(buf);
1466                 return ERR_PTR(rc);
1467         }
1468
1469         return buf;
1470 }
1471 EXPORT_SYMBOL_GPL(nvmem_cell_read);
1472
1473 static void *nvmem_cell_prepare_write_buffer(struct nvmem_cell_entry *cell,
1474                                              u8 *_buf, int len)
1475 {
1476         struct nvmem_device *nvmem = cell->nvmem;
1477         int i, rc, nbits, bit_offset = cell->bit_offset;
1478         u8 v, *p, *buf, *b, pbyte, pbits;
1479
1480         nbits = cell->nbits;
1481         buf = kzalloc(cell->bytes, GFP_KERNEL);
1482         if (!buf)
1483                 return ERR_PTR(-ENOMEM);
1484
1485         memcpy(buf, _buf, len);
1486         p = b = buf;
1487
1488         if (bit_offset) {
1489                 pbyte = *b;
1490                 *b <<= bit_offset;
1491
1492                 /* setup the first byte with lsb bits from nvmem */
1493                 rc = nvmem_reg_read(nvmem, cell->offset, &v, 1);
1494                 if (rc)
1495                         goto err;
1496                 *b++ |= GENMASK(bit_offset - 1, 0) & v;
1497
1498                 /* setup rest of the byte if any */
1499                 for (i = 1; i < cell->bytes; i++) {
1500                         /* Get last byte bits and shift them towards lsb */
1501                         pbits = pbyte >> (BITS_PER_BYTE - 1 - bit_offset);
1502                         pbyte = *b;
1503                         p = b;
1504                         *b <<= bit_offset;
1505                         *b++ |= pbits;
1506                 }
1507         }
1508
1509         /* if it's not end on byte boundary */
1510         if ((nbits + bit_offset) % BITS_PER_BYTE) {
1511                 /* setup the last byte with msb bits from nvmem */
1512                 rc = nvmem_reg_read(nvmem,
1513                                     cell->offset + cell->bytes - 1, &v, 1);
1514                 if (rc)
1515                         goto err;
1516                 *p |= GENMASK(7, (nbits + bit_offset) % BITS_PER_BYTE) & v;
1517
1518         }
1519
1520         return buf;
1521 err:
1522         kfree(buf);
1523         return ERR_PTR(rc);
1524 }
1525
1526 static int __nvmem_cell_entry_write(struct nvmem_cell_entry *cell, void *buf, size_t len)
1527 {
1528         struct nvmem_device *nvmem = cell->nvmem;
1529         int rc;
1530
1531         if (!nvmem || nvmem->read_only ||
1532             (cell->bit_offset == 0 && len != cell->bytes))
1533                 return -EINVAL;
1534
1535         if (cell->bit_offset || cell->nbits) {
1536                 buf = nvmem_cell_prepare_write_buffer(cell, buf, len);
1537                 if (IS_ERR(buf))
1538                         return PTR_ERR(buf);
1539         }
1540
1541         rc = nvmem_reg_write(nvmem, cell->offset, buf, cell->bytes);
1542
1543         /* free the tmp buffer */
1544         if (cell->bit_offset || cell->nbits)
1545                 kfree(buf);
1546
1547         if (rc)
1548                 return rc;
1549
1550         return len;
1551 }
1552
1553 /**
1554  * nvmem_cell_write() - Write to a given nvmem cell
1555  *
1556  * @cell: nvmem cell to be written.
1557  * @buf: Buffer to be written.
1558  * @len: length of buffer to be written to nvmem cell.
1559  *
1560  * Return: length of bytes written or negative on failure.
1561  */
1562 int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len)
1563 {
1564         return __nvmem_cell_entry_write(cell->entry, buf, len);
1565 }
1566
1567 EXPORT_SYMBOL_GPL(nvmem_cell_write);
1568
1569 static int nvmem_cell_read_common(struct device *dev, const char *cell_id,
1570                                   void *val, size_t count)
1571 {
1572         struct nvmem_cell *cell;
1573         void *buf;
1574         size_t len;
1575
1576         cell = nvmem_cell_get(dev, cell_id);
1577         if (IS_ERR(cell))
1578                 return PTR_ERR(cell);
1579
1580         buf = nvmem_cell_read(cell, &len);
1581         if (IS_ERR(buf)) {
1582                 nvmem_cell_put(cell);
1583                 return PTR_ERR(buf);
1584         }
1585         if (len != count) {
1586                 kfree(buf);
1587                 nvmem_cell_put(cell);
1588                 return -EINVAL;
1589         }
1590         memcpy(val, buf, count);
1591         kfree(buf);
1592         nvmem_cell_put(cell);
1593
1594         return 0;
1595 }
1596
1597 /**
1598  * nvmem_cell_read_u8() - Read a cell value as a u8
1599  *
1600  * @dev: Device that requests the nvmem cell.
1601  * @cell_id: Name of nvmem cell to read.
1602  * @val: pointer to output value.
1603  *
1604  * Return: 0 on success or negative errno.
1605  */
1606 int nvmem_cell_read_u8(struct device *dev, const char *cell_id, u8 *val)
1607 {
1608         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1609 }
1610 EXPORT_SYMBOL_GPL(nvmem_cell_read_u8);
1611
1612 /**
1613  * nvmem_cell_read_u16() - Read a cell value as a u16
1614  *
1615  * @dev: Device that requests the nvmem cell.
1616  * @cell_id: Name of nvmem cell to read.
1617  * @val: pointer to output value.
1618  *
1619  * Return: 0 on success or negative errno.
1620  */
1621 int nvmem_cell_read_u16(struct device *dev, const char *cell_id, u16 *val)
1622 {
1623         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1624 }
1625 EXPORT_SYMBOL_GPL(nvmem_cell_read_u16);
1626
1627 /**
1628  * nvmem_cell_read_u32() - Read a cell value as a u32
1629  *
1630  * @dev: Device that requests the nvmem cell.
1631  * @cell_id: Name of nvmem cell to read.
1632  * @val: pointer to output value.
1633  *
1634  * Return: 0 on success or negative errno.
1635  */
1636 int nvmem_cell_read_u32(struct device *dev, const char *cell_id, u32 *val)
1637 {
1638         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1639 }
1640 EXPORT_SYMBOL_GPL(nvmem_cell_read_u32);
1641
1642 /**
1643  * nvmem_cell_read_u64() - Read a cell value as a u64
1644  *
1645  * @dev: Device that requests the nvmem cell.
1646  * @cell_id: Name of nvmem cell to read.
1647  * @val: pointer to output value.
1648  *
1649  * Return: 0 on success or negative errno.
1650  */
1651 int nvmem_cell_read_u64(struct device *dev, const char *cell_id, u64 *val)
1652 {
1653         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1654 }
1655 EXPORT_SYMBOL_GPL(nvmem_cell_read_u64);
1656
1657 static const void *nvmem_cell_read_variable_common(struct device *dev,
1658                                                    const char *cell_id,
1659                                                    size_t max_len, size_t *len)
1660 {
1661         struct nvmem_cell *cell;
1662         int nbits;
1663         void *buf;
1664
1665         cell = nvmem_cell_get(dev, cell_id);
1666         if (IS_ERR(cell))
1667                 return cell;
1668
1669         nbits = cell->entry->nbits;
1670         buf = nvmem_cell_read(cell, len);
1671         nvmem_cell_put(cell);
1672         if (IS_ERR(buf))
1673                 return buf;
1674
1675         /*
1676          * If nbits is set then nvmem_cell_read() can significantly exaggerate
1677          * the length of the real data. Throw away the extra junk.
1678          */
1679         if (nbits)
1680                 *len = DIV_ROUND_UP(nbits, 8);
1681
1682         if (*len > max_len) {
1683                 kfree(buf);
1684                 return ERR_PTR(-ERANGE);
1685         }
1686
1687         return buf;
1688 }
1689
1690 /**
1691  * nvmem_cell_read_variable_le_u32() - Read up to 32-bits of data as a little endian number.
1692  *
1693  * @dev: Device that requests the nvmem cell.
1694  * @cell_id: Name of nvmem cell to read.
1695  * @val: pointer to output value.
1696  *
1697  * Return: 0 on success or negative errno.
1698  */
1699 int nvmem_cell_read_variable_le_u32(struct device *dev, const char *cell_id,
1700                                     u32 *val)
1701 {
1702         size_t len;
1703         const u8 *buf;
1704         int i;
1705
1706         buf = nvmem_cell_read_variable_common(dev, cell_id, sizeof(*val), &len);
1707         if (IS_ERR(buf))
1708                 return PTR_ERR(buf);
1709
1710         /* Copy w/ implicit endian conversion */
1711         *val = 0;
1712         for (i = 0; i < len; i++)
1713                 *val |= buf[i] << (8 * i);
1714
1715         kfree(buf);
1716
1717         return 0;
1718 }
1719 EXPORT_SYMBOL_GPL(nvmem_cell_read_variable_le_u32);
1720
1721 /**
1722  * nvmem_cell_read_variable_le_u64() - Read up to 64-bits of data as a little endian number.
1723  *
1724  * @dev: Device that requests the nvmem cell.
1725  * @cell_id: Name of nvmem cell to read.
1726  * @val: pointer to output value.
1727  *
1728  * Return: 0 on success or negative errno.
1729  */
1730 int nvmem_cell_read_variable_le_u64(struct device *dev, const char *cell_id,
1731                                     u64 *val)
1732 {
1733         size_t len;
1734         const u8 *buf;
1735         int i;
1736
1737         buf = nvmem_cell_read_variable_common(dev, cell_id, sizeof(*val), &len);
1738         if (IS_ERR(buf))
1739                 return PTR_ERR(buf);
1740
1741         /* Copy w/ implicit endian conversion */
1742         *val = 0;
1743         for (i = 0; i < len; i++)
1744                 *val |= (uint64_t)buf[i] << (8 * i);
1745
1746         kfree(buf);
1747
1748         return 0;
1749 }
1750 EXPORT_SYMBOL_GPL(nvmem_cell_read_variable_le_u64);
1751
1752 /**
1753  * nvmem_device_cell_read() - Read a given nvmem device and cell
1754  *
1755  * @nvmem: nvmem device to read from.
1756  * @info: nvmem cell info to be read.
1757  * @buf: buffer pointer which will be populated on successful read.
1758  *
1759  * Return: length of successful bytes read on success and negative
1760  * error code on error.
1761  */
1762 ssize_t nvmem_device_cell_read(struct nvmem_device *nvmem,
1763                            struct nvmem_cell_info *info, void *buf)
1764 {
1765         struct nvmem_cell_entry cell;
1766         int rc;
1767         ssize_t len;
1768
1769         if (!nvmem)
1770                 return -EINVAL;
1771
1772         rc = nvmem_cell_info_to_nvmem_cell_entry_nodup(nvmem, info, &cell);
1773         if (rc)
1774                 return rc;
1775
1776         rc = __nvmem_cell_read(nvmem, &cell, buf, &len, NULL);
1777         if (rc)
1778                 return rc;
1779
1780         return len;
1781 }
1782 EXPORT_SYMBOL_GPL(nvmem_device_cell_read);
1783
1784 /**
1785  * nvmem_device_cell_write() - Write cell to a given nvmem device
1786  *
1787  * @nvmem: nvmem device to be written to.
1788  * @info: nvmem cell info to be written.
1789  * @buf: buffer to be written to cell.
1790  *
1791  * Return: length of bytes written or negative error code on failure.
1792  */
1793 int nvmem_device_cell_write(struct nvmem_device *nvmem,
1794                             struct nvmem_cell_info *info, void *buf)
1795 {
1796         struct nvmem_cell_entry cell;
1797         int rc;
1798
1799         if (!nvmem)
1800                 return -EINVAL;
1801
1802         rc = nvmem_cell_info_to_nvmem_cell_entry_nodup(nvmem, info, &cell);
1803         if (rc)
1804                 return rc;
1805
1806         return __nvmem_cell_entry_write(&cell, buf, cell.bytes);
1807 }
1808 EXPORT_SYMBOL_GPL(nvmem_device_cell_write);
1809
1810 /**
1811  * nvmem_device_read() - Read from a given nvmem device
1812  *
1813  * @nvmem: nvmem device to read from.
1814  * @offset: offset in nvmem device.
1815  * @bytes: number of bytes to read.
1816  * @buf: buffer pointer which will be populated on successful read.
1817  *
1818  * Return: length of successful bytes read on success and negative
1819  * error code on error.
1820  */
1821 int nvmem_device_read(struct nvmem_device *nvmem,
1822                       unsigned int offset,
1823                       size_t bytes, void *buf)
1824 {
1825         int rc;
1826
1827         if (!nvmem)
1828                 return -EINVAL;
1829
1830         rc = nvmem_reg_read(nvmem, offset, buf, bytes);
1831
1832         if (rc)
1833                 return rc;
1834
1835         return bytes;
1836 }
1837 EXPORT_SYMBOL_GPL(nvmem_device_read);
1838
1839 /**
1840  * nvmem_device_write() - Write cell to a given nvmem device
1841  *
1842  * @nvmem: nvmem device to be written to.
1843  * @offset: offset in nvmem device.
1844  * @bytes: number of bytes to write.
1845  * @buf: buffer to be written.
1846  *
1847  * Return: length of bytes written or negative error code on failure.
1848  */
1849 int nvmem_device_write(struct nvmem_device *nvmem,
1850                        unsigned int offset,
1851                        size_t bytes, void *buf)
1852 {
1853         int rc;
1854
1855         if (!nvmem)
1856                 return -EINVAL;
1857
1858         rc = nvmem_reg_write(nvmem, offset, buf, bytes);
1859
1860         if (rc)
1861                 return rc;
1862
1863
1864         return bytes;
1865 }
1866 EXPORT_SYMBOL_GPL(nvmem_device_write);
1867
1868 /**
1869  * nvmem_add_cell_table() - register a table of cell info entries
1870  *
1871  * @table: table of cell info entries
1872  */
1873 void nvmem_add_cell_table(struct nvmem_cell_table *table)
1874 {
1875         mutex_lock(&nvmem_cell_mutex);
1876         list_add_tail(&table->node, &nvmem_cell_tables);
1877         mutex_unlock(&nvmem_cell_mutex);
1878 }
1879 EXPORT_SYMBOL_GPL(nvmem_add_cell_table);
1880
1881 /**
1882  * nvmem_del_cell_table() - remove a previously registered cell info table
1883  *
1884  * @table: table of cell info entries
1885  */
1886 void nvmem_del_cell_table(struct nvmem_cell_table *table)
1887 {
1888         mutex_lock(&nvmem_cell_mutex);
1889         list_del(&table->node);
1890         mutex_unlock(&nvmem_cell_mutex);
1891 }
1892 EXPORT_SYMBOL_GPL(nvmem_del_cell_table);
1893
1894 /**
1895  * nvmem_add_cell_lookups() - register a list of cell lookup entries
1896  *
1897  * @entries: array of cell lookup entries
1898  * @nentries: number of cell lookup entries in the array
1899  */
1900 void nvmem_add_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
1901 {
1902         int i;
1903
1904         mutex_lock(&nvmem_lookup_mutex);
1905         for (i = 0; i < nentries; i++)
1906                 list_add_tail(&entries[i].node, &nvmem_lookup_list);
1907         mutex_unlock(&nvmem_lookup_mutex);
1908 }
1909 EXPORT_SYMBOL_GPL(nvmem_add_cell_lookups);
1910
1911 /**
1912  * nvmem_del_cell_lookups() - remove a list of previously added cell lookup
1913  *                            entries
1914  *
1915  * @entries: array of cell lookup entries
1916  * @nentries: number of cell lookup entries in the array
1917  */
1918 void nvmem_del_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
1919 {
1920         int i;
1921
1922         mutex_lock(&nvmem_lookup_mutex);
1923         for (i = 0; i < nentries; i++)
1924                 list_del(&entries[i].node);
1925         mutex_unlock(&nvmem_lookup_mutex);
1926 }
1927 EXPORT_SYMBOL_GPL(nvmem_del_cell_lookups);
1928
1929 /**
1930  * nvmem_dev_name() - Get the name of a given nvmem device.
1931  *
1932  * @nvmem: nvmem device.
1933  *
1934  * Return: name of the nvmem device.
1935  */
1936 const char *nvmem_dev_name(struct nvmem_device *nvmem)
1937 {
1938         return dev_name(&nvmem->dev);
1939 }
1940 EXPORT_SYMBOL_GPL(nvmem_dev_name);
1941
1942 static int __init nvmem_init(void)
1943 {
1944         return bus_register(&nvmem_bus_type);
1945 }
1946
1947 static void __exit nvmem_exit(void)
1948 {
1949         bus_unregister(&nvmem_bus_type);
1950 }
1951
1952 subsys_initcall(nvmem_init);
1953 module_exit(nvmem_exit);
1954
1955 MODULE_AUTHOR("Srinivas Kandagatla <srinivas.kandagatla@linaro.org");
1956 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com");
1957 MODULE_DESCRIPTION("nvmem Driver Core");
1958 MODULE_LICENSE("GPL v2");