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
 471         if (cell->nbits)
 472                 cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
 473                                            BITS_PER_BYTE);
 474
 475         if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
 476                 dev_err(&nvmem->dev,
 477                         "cell %s unaligned to nvmem stride %d\n",
 478                         cell->name ?: "<unknown>", nvmem->stride);
 479                 return -EINVAL;
 480         }
 481
 482         return 0;
 483 }
 484
 485 static int nvmem_cell_info_to_nvmem_cell_entry(struct nvmem_device *nvmem,
 486                                                const struct nvmem_cell_info *info,
 487                                                struct nvmem_cell_entry *cell)
 488 {
 489         int err;
 490
 491         err = nvmem_cell_info_to_nvmem_cell_entry_nodup(nvmem, info, cell);
 492         if (err)
 493                 return err;
 494
 495         cell->name = kstrdup_const(info->name, GFP_KERNEL);
 496         if (!cell->name)
 497                 return -ENOMEM;
 498
 499         return 0;
 500 }
 501
 502 /**
 503  * nvmem_add_cells() - Add cell information to an nvmem device
 504  *
 505  * @nvmem: nvmem device to add cells to.
 506  * @info: nvmem cell info to add to the device
 507  * @ncells: number of cells in info
 508  *
 509  * Return: 0 or negative error code on failure.
 510  */
 511 static int nvmem_add_cells(struct nvmem_device *nvmem,
 512                     const struct nvmem_cell_info *info,
 513                     int ncells)
 514 {
 515         struct nvmem_cell_entry **cells;
 516         int i, rval;
 517
 518         cells = kcalloc(ncells, sizeof(*cells), GFP_KERNEL);
 519         if (!cells)
 520                 return -ENOMEM;
 521
 522         for (i = 0; i < ncells; i++) {
 523                 cells[i] = kzalloc(sizeof(**cells), GFP_KERNEL);
 524                 if (!cells[i]) {
 525                         rval = -ENOMEM;
 526                         goto err;
 527                 }
 528
 529                 rval = nvmem_cell_info_to_nvmem_cell_entry(nvmem, &info[i], cells[i]);
 530                 if (rval) {
 531                         kfree(cells[i]);
 532                         goto err;
 533                 }
 534
 535                 nvmem_cell_entry_add(cells[i]);
 536         }
 537
 538         /* remove tmp array */
 539         kfree(cells);
 540
 541         return 0;
 542 err:
 543         while (i--)
 544                 nvmem_cell_entry_drop(cells[i]);
 545
 546         kfree(cells);
 547
 548         return rval;
 549 }
 550
 551 /**
 552  * nvmem_register_notifier() - Register a notifier block for nvmem events.
 553  *
 554  * @nb: notifier block to be called on nvmem events.
 555  *
 556  * Return: 0 on success, negative error number on failure.
 557  */
 558 int nvmem_register_notifier(struct notifier_block *nb)
 559 {
 560         return blocking_notifier_chain_register(&nvmem_notifier, nb);
 561 }
 562 EXPORT_SYMBOL_GPL(nvmem_register_notifier);
 563
 564 /**
 565  * nvmem_unregister_notifier() - Unregister a notifier block for nvmem events.
 566  *
 567  * @nb: notifier block to be unregistered.
 568  *
 569  * Return: 0 on success, negative error number on failure.
 570  */
 571 int nvmem_unregister_notifier(struct notifier_block *nb)
 572 {
 573         return blocking_notifier_chain_unregister(&nvmem_notifier, nb);
 574 }
 575 EXPORT_SYMBOL_GPL(nvmem_unregister_notifier);
 576
 577 static int nvmem_add_cells_from_table(struct nvmem_device *nvmem)
 578 {
 579         const struct nvmem_cell_info *info;
 580         struct nvmem_cell_table *table;
 581         struct nvmem_cell_entry *cell;
 582         int rval = 0, i;
 583
 584         mutex_lock(&nvmem_cell_mutex);
 585         list_for_each_entry(table, &nvmem_cell_tables, node) {
 586                 if (strcmp(nvmem_dev_name(nvmem), table->nvmem_name) == 0) {
 587                         for (i = 0; i < table->ncells; i++) {
 588                                 info = &table->cells[i];
 589
 590                                 cell = kzalloc(sizeof(*cell), GFP_KERNEL);
 591                                 if (!cell) {
 592                                         rval = -ENOMEM;
 593                                         goto out;
 594                                 }
 595
 596                                 rval = nvmem_cell_info_to_nvmem_cell_entry(nvmem, info, cell);
 597                                 if (rval) {
 598                                         kfree(cell);
 599                                         goto out;
 600                                 }
 601
 602                                 nvmem_cell_entry_add(cell);
 603                         }
 604                 }
 605         }
 606
 607 out:
 608         mutex_unlock(&nvmem_cell_mutex);
 609         return rval;
 610 }
 611
 612 static struct nvmem_cell_entry *
 613 nvmem_find_cell_entry_by_name(struct nvmem_device *nvmem, const char *cell_id)
 614 {
 615         struct nvmem_cell_entry *iter, *cell = NULL;
 616
 617         mutex_lock(&nvmem_mutex);
 618         list_for_each_entry(iter, &nvmem->cells, node) {
 619                 if (strcmp(cell_id, iter->name) == 0) {
 620                         cell = iter;
 621                         break;
 622                 }
 623         }
 624         mutex_unlock(&nvmem_mutex);
 625
 626         return cell;
 627 }
 628
 629 static int nvmem_validate_keepouts(struct nvmem_device *nvmem)
 630 {
 631         unsigned int cur = 0;
 632         const struct nvmem_keepout *keepout = nvmem->keepout;
 633         const struct nvmem_keepout *keepoutend = keepout + nvmem->nkeepout;
 634
 635         while (keepout < keepoutend) {
 636                 /* Ensure keepouts are sorted and don't overlap. */
 637                 if (keepout->start < cur) {
 638                         dev_err(&nvmem->dev,
 639                                 "Keepout regions aren't sorted or overlap.\n");
 640
 641                         return -ERANGE;
 642                 }
 643
 644                 if (keepout->end < keepout->start) {
 645                         dev_err(&nvmem->dev,
 646                                 "Invalid keepout region.\n");
 647
 648                         return -EINVAL;
 649                 }
 650
 651                 /*
 652                  * Validate keepouts (and holes between) don't violate
 653                  * word_size constraints.
 654                  */
 655                 if ((keepout->end - keepout->start < nvmem->word_size) ||
 656                     ((keepout->start != cur) &&
 657                      (keepout->start - cur < nvmem->word_size))) {
 658
 659                         dev_err(&nvmem->dev,
 660                                 "Keepout regions violate word_size constraints.\n");
 661
 662                         return -ERANGE;
 663                 }
 664
 665                 /* Validate keepouts don't violate stride (alignment). */
 666                 if (!IS_ALIGNED(keepout->start, nvmem->stride) ||
 667                     !IS_ALIGNED(keepout->end, nvmem->stride)) {
 668
 669                         dev_err(&nvmem->dev,
 670                                 "Keepout regions violate stride.\n");
 671
 672                         return -EINVAL;
 673                 }
 674
 675                 cur = keepout->end;
 676                 keepout++;
 677         }
 678
 679         return 0;
 680 }
 681
 682 static int nvmem_add_cells_from_of(struct nvmem_device *nvmem)
 683 {
 684         struct device_node *parent, *child;
 685         struct device *dev = &nvmem->dev;
 686         struct nvmem_cell_entry *cell;
 687         const __be32 *addr;
 688         int len;
 689
 690         parent = dev->of_node;
 691
 692         for_each_child_of_node(parent, child) {
 693                 addr = of_get_property(child, "reg", &len);
 694                 if (!addr)
 695                         continue;
 696                 if (len < 2 * sizeof(u32)) {
 697                         dev_err(dev, "nvmem: invalid reg on %pOF\n", child);
 698                         of_node_put(child);
 699                         return -EINVAL;
 700                 }
 701
 702                 cell = kzalloc(sizeof(*cell), GFP_KERNEL);
 703                 if (!cell) {
 704                         of_node_put(child);
 705                         return -ENOMEM;
 706                 }
 707
 708                 cell->nvmem = nvmem;
 709                 cell->offset = be32_to_cpup(addr++);
 710                 cell->bytes = be32_to_cpup(addr);
 711                 cell->name = kasprintf(GFP_KERNEL, "%pOFn", child);
 712
 713                 addr = of_get_property(child, "bits", &len);
 714                 if (addr && len == (2 * sizeof(u32))) {
 715                         cell->bit_offset = be32_to_cpup(addr++);
 716                         cell->nbits = be32_to_cpup(addr);
 717                 }
 718
 719                 if (cell->nbits)
 720                         cell->bytes = DIV_ROUND_UP(
 721                                         cell->nbits + cell->bit_offset,
 722                                         BITS_PER_BYTE);
 723
 724                 if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
 725                         dev_err(dev, "cell %s unaligned to nvmem stride %d\n",
 726                                 cell->name, nvmem->stride);
 727                         /* Cells already added will be freed later. */
 728                         kfree_const(cell->name);
 729                         kfree(cell);
 730                         of_node_put(child);
 731                         return -EINVAL;
 732                 }
 733
 734                 cell->np = of_node_get(child);
 735                 nvmem_cell_entry_add(cell);
 736         }
 737
 738         return 0;
 739 }
 740
 741 /**
 742  * nvmem_register() - Register a nvmem device for given nvmem_config.
 743  * Also creates a binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
 744  *
 745  * @config: nvmem device configuration with which nvmem device is created.
 746  *
 747  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
 748  * on success.
 749  */
 750
 751 struct nvmem_device *nvmem_register(const struct nvmem_config *config)
 752 {
 753         struct nvmem_device *nvmem;
 754         int rval;
 755
 756         if (!config->dev)
 757                 return ERR_PTR(-EINVAL);
 758
 759         if (!config->reg_read && !config->reg_write)
 760                 return ERR_PTR(-EINVAL);
 761
 762         nvmem = kzalloc(sizeof(*nvmem), GFP_KERNEL);
 763         if (!nvmem)
 764                 return ERR_PTR(-ENOMEM);
 765
 766         rval  = ida_alloc(&nvmem_ida, GFP_KERNEL);
 767         if (rval < 0) {
 768                 kfree(nvmem);
 769                 return ERR_PTR(rval);
 770         }
 771
 772         if (config->wp_gpio)
 773                 nvmem->wp_gpio = config->wp_gpio;
 774         else
 775                 nvmem->wp_gpio = gpiod_get_optional(config->dev, "wp",
 776                                                     GPIOD_OUT_HIGH);
 777         if (IS_ERR(nvmem->wp_gpio)) {
 778                 ida_free(&nvmem_ida, nvmem->id);
 779                 rval = PTR_ERR(nvmem->wp_gpio);
 780                 kfree(nvmem);
 781                 return ERR_PTR(rval);
 782         }
 783
 784         kref_init(&nvmem->refcnt);
 785         INIT_LIST_HEAD(&nvmem->cells);
 786
 787         nvmem->id = rval;
 788         nvmem->owner = config->owner;
 789         if (!nvmem->owner && config->dev->driver)
 790                 nvmem->owner = config->dev->driver->owner;
 791         nvmem->stride = config->stride ?: 1;
 792         nvmem->word_size = config->word_size ?: 1;
 793         nvmem->size = config->size;
 794         nvmem->dev.type = &nvmem_provider_type;
 795         nvmem->dev.bus = &nvmem_bus_type;
 796         nvmem->dev.parent = config->dev;
 797         nvmem->root_only = config->root_only;
 798         nvmem->priv = config->priv;
 799         nvmem->type = config->type;
 800         nvmem->reg_read = config->reg_read;
 801         nvmem->reg_write = config->reg_write;
 802         nvmem->cell_post_process = config->cell_post_process;
 803         nvmem->keepout = config->keepout;
 804         nvmem->nkeepout = config->nkeepout;
 805         if (config->of_node)
 806                 nvmem->dev.of_node = config->of_node;
 807         else if (!config->no_of_node)
 808                 nvmem->dev.of_node = config->dev->of_node;
 809
 810         switch (config->id) {
 811         case NVMEM_DEVID_NONE:
 812                 dev_set_name(&nvmem->dev, "%s", config->name);
 813                 break;
 814         case NVMEM_DEVID_AUTO:
 815                 dev_set_name(&nvmem->dev, "%s%d", config->name, nvmem->id);
 816                 break;
 817         default:
 818                 dev_set_name(&nvmem->dev, "%s%d",
 819                              config->name ? : "nvmem",
 820                              config->name ? config->id : nvmem->id);
 821                 break;
 822         }
 823
 824         nvmem->read_only = device_property_present(config->dev, "read-only") ||
 825                            config->read_only || !nvmem->reg_write;
 826
 827 #ifdef CONFIG_NVMEM_SYSFS
 828         nvmem->dev.groups = nvmem_dev_groups;
 829 #endif
 830
 831         if (nvmem->nkeepout) {
 832                 rval = nvmem_validate_keepouts(nvmem);
 833                 if (rval) {
 834                         ida_free(&nvmem_ida, nvmem->id);
 835                         kfree(nvmem);
 836                         return ERR_PTR(rval);
 837                 }
 838         }
 839
 840         dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
 841
 842         rval = device_register(&nvmem->dev);
 843         if (rval)
 844                 goto err_put_device;
 845
 846         if (config->compat) {
 847                 rval = nvmem_sysfs_setup_compat(nvmem, config);
 848                 if (rval)
 849                         goto err_device_del;
 850         }
 851
 852         if (config->cells) {
 853                 rval = nvmem_add_cells(nvmem, config->cells, config->ncells);
 854                 if (rval)
 855                         goto err_teardown_compat;
 856         }
 857
 858         rval = nvmem_add_cells_from_table(nvmem);
 859         if (rval)
 860                 goto err_remove_cells;
 861
 862         rval = nvmem_add_cells_from_of(nvmem);
 863         if (rval)
 864                 goto err_remove_cells;
 865
 866         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem);
 867
 868         return nvmem;
 869
 870 err_remove_cells:
 871         nvmem_device_remove_all_cells(nvmem);
 872 err_teardown_compat:
 873         if (config->compat)
 874                 nvmem_sysfs_remove_compat(nvmem, config);
 875 err_device_del:
 876         device_del(&nvmem->dev);
 877 err_put_device:
 878         put_device(&nvmem->dev);
 879
 880         return ERR_PTR(rval);
 881 }
 882 EXPORT_SYMBOL_GPL(nvmem_register);
 883
 884 static void nvmem_device_release(struct kref *kref)
 885 {
 886         struct nvmem_device *nvmem;
 887
 888         nvmem = container_of(kref, struct nvmem_device, refcnt);
 889
 890         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_REMOVE, nvmem);
 891
 892         if (nvmem->flags & FLAG_COMPAT)
 893                 device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
 894
 895         nvmem_device_remove_all_cells(nvmem);
 896         device_unregister(&nvmem->dev);
 897 }
 898
 899 /**
 900  * nvmem_unregister() - Unregister previously registered nvmem device
 901  *
 902  * @nvmem: Pointer to previously registered nvmem device.
 903  */
 904 void nvmem_unregister(struct nvmem_device *nvmem)
 905 {
 906         if (nvmem)
 907                 kref_put(&nvmem->refcnt, nvmem_device_release);
 908 }
 909 EXPORT_SYMBOL_GPL(nvmem_unregister);
 910
 911 static void devm_nvmem_unregister(void *nvmem)
 912 {
 913         nvmem_unregister(nvmem);
 914 }
 915
 916 /**
 917  * devm_nvmem_register() - Register a managed nvmem device for given
 918  * nvmem_config.
 919  * Also creates a binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
 920  *
 921  * @dev: Device that uses the nvmem device.
 922  * @config: nvmem device configuration with which nvmem device is created.
 923  *
 924  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
 925  * on success.
 926  */
 927 struct nvmem_device *devm_nvmem_register(struct device *dev,
 928                                          const struct nvmem_config *config)
 929 {
 930         struct nvmem_device *nvmem;
 931         int ret;
 932
 933         nvmem = nvmem_register(config);
 934         if (IS_ERR(nvmem))
 935                 return nvmem;
 936
 937         ret = devm_add_action_or_reset(dev, devm_nvmem_unregister, nvmem);
 938         if (ret)
 939                 return ERR_PTR(ret);
 940
 941         return nvmem;
 942 }
 943 EXPORT_SYMBOL_GPL(devm_nvmem_register);
 944
 945 static struct nvmem_device *__nvmem_device_get(void *data,
 946                         int (*match)(struct device *dev, const void *data))
 947 {
 948         struct nvmem_device *nvmem = NULL;
 949         struct device *dev;
 950
 951         mutex_lock(&nvmem_mutex);
 952         dev = bus_find_device(&nvmem_bus_type, NULL, data, match);
 953         if (dev)
 954                 nvmem = to_nvmem_device(dev);
 955         mutex_unlock(&nvmem_mutex);
 956         if (!nvmem)
 957                 return ERR_PTR(-EPROBE_DEFER);
 958
 959         if (!try_module_get(nvmem->owner)) {
 960                 dev_err(&nvmem->dev,
 961                         "could not increase module refcount for cell %s\n",
 962                         nvmem_dev_name(nvmem));
 963
 964                 put_device(&nvmem->dev);
 965                 return ERR_PTR(-EINVAL);
 966         }
 967
 968         kref_get(&nvmem->refcnt);
 969
 970         return nvmem;
 971 }
 972
 973 static void __nvmem_device_put(struct nvmem_device *nvmem)
 974 {
 975         put_device(&nvmem->dev);
 976         module_put(nvmem->owner);
 977         kref_put(&nvmem->refcnt, nvmem_device_release);
 978 }
 979
 980 #if IS_ENABLED(CONFIG_OF)
 981 /**
 982  * of_nvmem_device_get() - Get nvmem device from a given id
 983  *
 984  * @np: Device tree node that uses the nvmem device.
 985  * @id: nvmem name from nvmem-names property.
 986  *
 987  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
 988  * on success.
 989  */
 990 struct nvmem_device *of_nvmem_device_get(struct device_node *np, const char *id)
 991 {
 992
 993         struct device_node *nvmem_np;
 994         struct nvmem_device *nvmem;
 995         int index = 0;
 996
 997         if (id)
 998                 index = of_property_match_string(np, "nvmem-names", id);
 999
1000         nvmem_np = of_parse_phandle(np, "nvmem", index);
1001         if (!nvmem_np)
1002                 return ERR_PTR(-ENOENT);
1003
1004         nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
1005         of_node_put(nvmem_np);
1006         return nvmem;
1007 }
1008 EXPORT_SYMBOL_GPL(of_nvmem_device_get);
1009 #endif
1010
1011 /**
1012  * nvmem_device_get() - Get nvmem device from a given id
1013  *
1014  * @dev: Device that uses the nvmem device.
1015  * @dev_name: name of the requested nvmem device.
1016  *
1017  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1018  * on success.
1019  */
1020 struct nvmem_device *nvmem_device_get(struct device *dev, const char *dev_name)
1021 {
1022         if (dev->of_node) { /* try dt first */
1023                 struct nvmem_device *nvmem;
1024
1025                 nvmem = of_nvmem_device_get(dev->of_node, dev_name);
1026
1027                 if (!IS_ERR(nvmem) || PTR_ERR(nvmem) == -EPROBE_DEFER)
1028                         return nvmem;
1029
1030         }
1031
1032         return __nvmem_device_get((void *)dev_name, device_match_name);
1033 }
1034 EXPORT_SYMBOL_GPL(nvmem_device_get);
1035
1036 /**
1037  * nvmem_device_find() - Find nvmem device with matching function
1038  *
1039  * @data: Data to pass to match function
1040  * @match: Callback function to check device
1041  *
1042  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1043  * on success.
1044  */
1045 struct nvmem_device *nvmem_device_find(void *data,
1046                         int (*match)(struct device *dev, const void *data))
1047 {
1048         return __nvmem_device_get(data, match);
1049 }
1050 EXPORT_SYMBOL_GPL(nvmem_device_find);
1051
1052 static int devm_nvmem_device_match(struct device *dev, void *res, void *data)
1053 {
1054         struct nvmem_device **nvmem = res;
1055
1056         if (WARN_ON(!nvmem || !*nvmem))
1057                 return 0;
1058
1059         return *nvmem == data;
1060 }
1061
1062 static void devm_nvmem_device_release(struct device *dev, void *res)
1063 {
1064         nvmem_device_put(*(struct nvmem_device **)res);
1065 }
1066
1067 /**
1068  * devm_nvmem_device_put() - put alredy got nvmem device
1069  *
1070  * @dev: Device that uses the nvmem device.
1071  * @nvmem: pointer to nvmem device allocated by devm_nvmem_cell_get(),
1072  * that needs to be released.
1073  */
1074 void devm_nvmem_device_put(struct device *dev, struct nvmem_device *nvmem)
1075 {
1076         int ret;
1077
1078         ret = devres_release(dev, devm_nvmem_device_release,
1079                              devm_nvmem_device_match, nvmem);
1080
1081         WARN_ON(ret);
1082 }
1083 EXPORT_SYMBOL_GPL(devm_nvmem_device_put);
1084
1085 /**
1086  * nvmem_device_put() - put alredy got nvmem device
1087  *
1088  * @nvmem: pointer to nvmem device that needs to be released.
1089  */
1090 void nvmem_device_put(struct nvmem_device *nvmem)
1091 {
1092         __nvmem_device_put(nvmem);
1093 }
1094 EXPORT_SYMBOL_GPL(nvmem_device_put);
1095
1096 /**
1097  * devm_nvmem_device_get() - Get nvmem cell of device form a given id
1098  *
1099  * @dev: Device that requests the nvmem device.
1100  * @id: name id for the requested nvmem device.
1101  *
1102  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_cell
1103  * on success.  The nvmem_cell will be freed by the automatically once the
1104  * device is freed.
1105  */
1106 struct nvmem_device *devm_nvmem_device_get(struct device *dev, const char *id)
1107 {
1108         struct nvmem_device **ptr, *nvmem;
1109
1110         ptr = devres_alloc(devm_nvmem_device_release, sizeof(*ptr), GFP_KERNEL);
1111         if (!ptr)
1112                 return ERR_PTR(-ENOMEM);
1113
1114         nvmem = nvmem_device_get(dev, id);
1115         if (!IS_ERR(nvmem)) {
1116                 *ptr = nvmem;
1117                 devres_add(dev, ptr);
1118         } else {
1119                 devres_free(ptr);
1120         }
1121
1122         return nvmem;
1123 }
1124 EXPORT_SYMBOL_GPL(devm_nvmem_device_get);
1125
1126 static struct nvmem_cell *nvmem_create_cell(struct nvmem_cell_entry *entry, const char *id)
1127 {
1128         struct nvmem_cell *cell;
1129         const char *name = NULL;
1130
1131         cell = kzalloc(sizeof(*cell), GFP_KERNEL);
1132         if (!cell)
1133                 return ERR_PTR(-ENOMEM);
1134
1135         if (id) {
1136                 name = kstrdup_const(id, GFP_KERNEL);
1137                 if (!name) {
1138                         kfree(cell);
1139                         return ERR_PTR(-ENOMEM);
1140                 }
1141         }
1142
1143         cell->id = name;
1144         cell->entry = entry;
1145
1146         return cell;
1147 }
1148
1149 static struct nvmem_cell *
1150 nvmem_cell_get_from_lookup(struct device *dev, const char *con_id)
1151 {
1152         struct nvmem_cell_entry *cell_entry;
1153         struct nvmem_cell *cell = ERR_PTR(-ENOENT);
1154         struct nvmem_cell_lookup *lookup;
1155         struct nvmem_device *nvmem;
1156         const char *dev_id;
1157
1158         if (!dev)
1159                 return ERR_PTR(-EINVAL);
1160
1161         dev_id = dev_name(dev);
1162
1163         mutex_lock(&nvmem_lookup_mutex);
1164
1165         list_for_each_entry(lookup, &nvmem_lookup_list, node) {
1166                 if ((strcmp(lookup->dev_id, dev_id) == 0) &&
1167                     (strcmp(lookup->con_id, con_id) == 0)) {
1168                         /* This is the right entry. */
1169                         nvmem = __nvmem_device_get((void *)lookup->nvmem_name,
1170                                                    device_match_name);
1171                         if (IS_ERR(nvmem)) {
1172                                 /* Provider may not be registered yet. */
1173                                 cell = ERR_CAST(nvmem);
1174                                 break;
1175                         }
1176
1177                         cell_entry = nvmem_find_cell_entry_by_name(nvmem,
1178                                                                    lookup->cell_name);
1179                         if (!cell_entry) {
1180                                 __nvmem_device_put(nvmem);
1181                                 cell = ERR_PTR(-ENOENT);
1182                         } else {
1183                                 cell = nvmem_create_cell(cell_entry, con_id);
1184                                 if (IS_ERR(cell))
1185                                         __nvmem_device_put(nvmem);
1186                         }
1187                         break;
1188                 }
1189         }
1190
1191         mutex_unlock(&nvmem_lookup_mutex);
1192         return cell;
1193 }
1194
1195 #if IS_ENABLED(CONFIG_OF)
1196 static struct nvmem_cell_entry *
1197 nvmem_find_cell_entry_by_node(struct nvmem_device *nvmem, struct device_node *np)
1198 {
1199         struct nvmem_cell_entry *iter, *cell = NULL;
1200
1201         mutex_lock(&nvmem_mutex);
1202         list_for_each_entry(iter, &nvmem->cells, node) {
1203                 if (np == iter->np) {
1204                         cell = iter;
1205                         break;
1206                 }
1207         }
1208         mutex_unlock(&nvmem_mutex);
1209
1210         return cell;
1211 }
1212
1213 /**
1214  * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
1215  *
1216  * @np: Device tree node that uses the nvmem cell.
1217  * @id: nvmem cell name from nvmem-cell-names property, or NULL
1218  *      for the cell at index 0 (the lone cell with no accompanying
1219  *      nvmem-cell-names property).
1220  *
1221  * Return: Will be an ERR_PTR() on error or a valid pointer
1222  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1223  * nvmem_cell_put().
1224  */
1225 struct nvmem_cell *of_nvmem_cell_get(struct device_node *np, const char *id)
1226 {
1227         struct device_node *cell_np, *nvmem_np;
1228         struct nvmem_device *nvmem;
1229         struct nvmem_cell_entry *cell_entry;
1230         struct nvmem_cell *cell;
1231         int index = 0;
1232
1233         /* if cell name exists, find index to the name */
1234         if (id)
1235                 index = of_property_match_string(np, "nvmem-cell-names", id);
1236
1237         cell_np = of_parse_phandle(np, "nvmem-cells", index);
1238         if (!cell_np)
1239                 return ERR_PTR(-ENOENT);
1240
1241         nvmem_np = of_get_next_parent(cell_np);
1242         if (!nvmem_np)
1243                 return ERR_PTR(-EINVAL);
1244
1245         nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
1246         of_node_put(nvmem_np);
1247         if (IS_ERR(nvmem))
1248                 return ERR_CAST(nvmem);
1249
1250         cell_entry = nvmem_find_cell_entry_by_node(nvmem, cell_np);
1251         if (!cell_entry) {
1252                 __nvmem_device_put(nvmem);
1253                 return ERR_PTR(-ENOENT);
1254         }
1255
1256         cell = nvmem_create_cell(cell_entry, id);
1257         if (IS_ERR(cell))
1258                 __nvmem_device_put(nvmem);
1259
1260         return cell;
1261 }
1262 EXPORT_SYMBOL_GPL(of_nvmem_cell_get);
1263 #endif
1264
1265 /**
1266  * nvmem_cell_get() - Get nvmem cell of device form a given cell name
1267  *
1268  * @dev: Device that requests the nvmem cell.
1269  * @id: nvmem cell name to get (this corresponds with the name from the
1270  *      nvmem-cell-names property for DT systems and with the con_id from
1271  *      the lookup entry for non-DT systems).
1272  *
1273  * Return: Will be an ERR_PTR() on error or a valid pointer
1274  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1275  * nvmem_cell_put().
1276  */
1277 struct nvmem_cell *nvmem_cell_get(struct device *dev, const char *id)
1278 {
1279         struct nvmem_cell *cell;
1280
1281         if (dev->of_node) { /* try dt first */
1282                 cell = of_nvmem_cell_get(dev->of_node, id);
1283                 if (!IS_ERR(cell) || PTR_ERR(cell) == -EPROBE_DEFER)
1284                         return cell;
1285         }
1286
1287         /* NULL cell id only allowed for device tree; invalid otherwise */
1288         if (!id)
1289                 return ERR_PTR(-EINVAL);
1290
1291         return nvmem_cell_get_from_lookup(dev, id);
1292 }
1293 EXPORT_SYMBOL_GPL(nvmem_cell_get);
1294
1295 static void devm_nvmem_cell_release(struct device *dev, void *res)
1296 {
1297         nvmem_cell_put(*(struct nvmem_cell **)res);
1298 }
1299
1300 /**
1301  * devm_nvmem_cell_get() - Get nvmem cell of device form a given id
1302  *
1303  * @dev: Device that requests the nvmem cell.
1304  * @id: nvmem cell name id to get.
1305  *
1306  * Return: Will be an ERR_PTR() on error or a valid pointer
1307  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1308  * automatically once the device is freed.
1309  */
1310 struct nvmem_cell *devm_nvmem_cell_get(struct device *dev, const char *id)
1311 {
1312         struct nvmem_cell **ptr, *cell;
1313
1314         ptr = devres_alloc(devm_nvmem_cell_release, sizeof(*ptr), GFP_KERNEL);
1315         if (!ptr)
1316                 return ERR_PTR(-ENOMEM);
1317
1318         cell = nvmem_cell_get(dev, id);
1319         if (!IS_ERR(cell)) {
1320                 *ptr = cell;
1321                 devres_add(dev, ptr);
1322         } else {
1323                 devres_free(ptr);
1324         }
1325
1326         return cell;
1327 }
1328 EXPORT_SYMBOL_GPL(devm_nvmem_cell_get);
1329
1330 static int devm_nvmem_cell_match(struct device *dev, void *res, void *data)
1331 {
1332         struct nvmem_cell **c = res;
1333
1334         if (WARN_ON(!c || !*c))
1335                 return 0;
1336
1337         return *c == data;
1338 }
1339
1340 /**
1341  * devm_nvmem_cell_put() - Release previously allocated nvmem cell
1342  * from devm_nvmem_cell_get.
1343  *
1344  * @dev: Device that requests the nvmem cell.
1345  * @cell: Previously allocated nvmem cell by devm_nvmem_cell_get().
1346  */
1347 void devm_nvmem_cell_put(struct device *dev, struct nvmem_cell *cell)
1348 {
1349         int ret;
1350
1351         ret = devres_release(dev, devm_nvmem_cell_release,
1352                                 devm_nvmem_cell_match, cell);
1353
1354         WARN_ON(ret);
1355 }
1356 EXPORT_SYMBOL(devm_nvmem_cell_put);
1357
1358 /**
1359  * nvmem_cell_put() - Release previously allocated nvmem cell.
1360  *
1361  * @cell: Previously allocated nvmem cell by nvmem_cell_get().
1362  */
1363 void nvmem_cell_put(struct nvmem_cell *cell)
1364 {
1365         struct nvmem_device *nvmem = cell->entry->nvmem;
1366
1367         if (cell->id)
1368                 kfree_const(cell->id);
1369
1370         kfree(cell);
1371         __nvmem_device_put(nvmem);
1372 }
1373 EXPORT_SYMBOL_GPL(nvmem_cell_put);
1374
1375 static void nvmem_shift_read_buffer_in_place(struct nvmem_cell_entry *cell, void *buf)
1376 {
1377         u8 *p, *b;
1378         int i, extra, bit_offset = cell->bit_offset;
1379
1380         p = b = buf;
1381         if (bit_offset) {
1382                 /* First shift */
1383                 *b++ >>= bit_offset;
1384
1385                 /* setup rest of the bytes if any */
1386                 for (i = 1; i < cell->bytes; i++) {
1387                         /* Get bits from next byte and shift them towards msb */
1388                         *p |= *b << (BITS_PER_BYTE - bit_offset);
1389
1390                         p = b;
1391                         *b++ >>= bit_offset;
1392                 }
1393         } else {
1394                 /* point to the msb */
1395                 p += cell->bytes - 1;
1396         }
1397
1398         /* result fits in less bytes */
1399         extra = cell->bytes - DIV_ROUND_UP(cell->nbits, BITS_PER_BYTE);
1400         while (--extra >= 0)
1401                 *p-- = 0;
1402
1403         /* clear msb bits if any leftover in the last byte */
1404         if (cell->nbits % BITS_PER_BYTE)
1405                 *p &= GENMASK((cell->nbits % BITS_PER_BYTE) - 1, 0);
1406 }
1407
1408 static int __nvmem_cell_read(struct nvmem_device *nvmem,
1409                       struct nvmem_cell_entry *cell,
1410                       void *buf, size_t *len, const char *id)
1411 {
1412         int rc;
1413
1414         rc = nvmem_reg_read(nvmem, cell->offset, buf, cell->bytes);
1415
1416         if (rc)
1417                 return rc;
1418
1419         /* shift bits in-place */
1420         if (cell->bit_offset || cell->nbits)
1421                 nvmem_shift_read_buffer_in_place(cell, buf);
1422
1423         if (nvmem->cell_post_process) {
1424                 rc = nvmem->cell_post_process(nvmem->priv, id,
1425                                               cell->offset, buf, cell->bytes);
1426                 if (rc)
1427                         return rc;
1428         }
1429
1430         if (len)
1431                 *len = cell->bytes;
1432
1433         return 0;
1434 }
1435
1436 /**
1437  * nvmem_cell_read() - Read a given nvmem cell
1438  *
1439  * @cell: nvmem cell to be read.
1440  * @len: pointer to length of cell which will be populated on successful read;
1441  *       can be NULL.
1442  *
1443  * Return: ERR_PTR() on error or a valid pointer to a buffer on success. The
1444  * buffer should be freed by the consumer with a kfree().
1445  */
1446 void *nvmem_cell_read(struct nvmem_cell *cell, size_t *len)
1447 {
1448         struct nvmem_device *nvmem = cell->entry->nvmem;
1449         u8 *buf;
1450         int rc;
1451
1452         if (!nvmem)
1453                 return ERR_PTR(-EINVAL);
1454
1455         buf = kzalloc(cell->entry->bytes, GFP_KERNEL);
1456         if (!buf)
1457                 return ERR_PTR(-ENOMEM);
1458
1459         rc = __nvmem_cell_read(nvmem, cell->entry, buf, len, cell->id);
1460         if (rc) {
1461                 kfree(buf);
1462                 return ERR_PTR(rc);
1463         }
1464
1465         return buf;
1466 }
1467 EXPORT_SYMBOL_GPL(nvmem_cell_read);
1468
1469 static void *nvmem_cell_prepare_write_buffer(struct nvmem_cell_entry *cell,
1470                                              u8 *_buf, int len)
1471 {
1472         struct nvmem_device *nvmem = cell->nvmem;
1473         int i, rc, nbits, bit_offset = cell->bit_offset;
1474         u8 v, *p, *buf, *b, pbyte, pbits;
1475
1476         nbits = cell->nbits;
1477         buf = kzalloc(cell->bytes, GFP_KERNEL);
1478         if (!buf)
1479                 return ERR_PTR(-ENOMEM);
1480
1481         memcpy(buf, _buf, len);
1482         p = b = buf;
1483
1484         if (bit_offset) {
1485                 pbyte = *b;
1486                 *b <<= bit_offset;
1487
1488                 /* setup the first byte with lsb bits from nvmem */
1489                 rc = nvmem_reg_read(nvmem, cell->offset, &v, 1);
1490                 if (rc)
1491                         goto err;
1492                 *b++ |= GENMASK(bit_offset - 1, 0) & v;
1493
1494                 /* setup rest of the byte if any */
1495                 for (i = 1; i < cell->bytes; i++) {
1496                         /* Get last byte bits and shift them towards lsb */
1497                         pbits = pbyte >> (BITS_PER_BYTE - 1 - bit_offset);
1498                         pbyte = *b;
1499                         p = b;
1500                         *b <<= bit_offset;
1501                         *b++ |= pbits;
1502                 }
1503         }
1504
1505         /* if it's not end on byte boundary */
1506         if ((nbits + bit_offset) % BITS_PER_BYTE) {
1507                 /* setup the last byte with msb bits from nvmem */
1508                 rc = nvmem_reg_read(nvmem,
1509                                     cell->offset + cell->bytes - 1, &v, 1);
1510                 if (rc)
1511                         goto err;
1512                 *p |= GENMASK(7, (nbits + bit_offset) % BITS_PER_BYTE) & v;
1513
1514         }
1515
1516         return buf;
1517 err:
1518         kfree(buf);
1519         return ERR_PTR(rc);
1520 }
1521
1522 static int __nvmem_cell_entry_write(struct nvmem_cell_entry *cell, void *buf, size_t len)
1523 {
1524         struct nvmem_device *nvmem = cell->nvmem;
1525         int rc;
1526
1527         if (!nvmem || nvmem->read_only ||
1528             (cell->bit_offset == 0 && len != cell->bytes))
1529                 return -EINVAL;
1530
1531         if (cell->bit_offset || cell->nbits) {
1532                 buf = nvmem_cell_prepare_write_buffer(cell, buf, len);
1533                 if (IS_ERR(buf))
1534                         return PTR_ERR(buf);
1535         }
1536
1537         rc = nvmem_reg_write(nvmem, cell->offset, buf, cell->bytes);
1538
1539         /* free the tmp buffer */
1540         if (cell->bit_offset || cell->nbits)
1541                 kfree(buf);
1542
1543         if (rc)
1544                 return rc;
1545
1546         return len;
1547 }
1548
1549 /**
1550  * nvmem_cell_write() - Write to a given nvmem cell
1551  *
1552  * @cell: nvmem cell to be written.
1553  * @buf: Buffer to be written.
1554  * @len: length of buffer to be written to nvmem cell.
1555  *
1556  * Return: length of bytes written or negative on failure.
1557  */
1558 int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len)
1559 {
1560         return __nvmem_cell_entry_write(cell->entry, buf, len);
1561 }
1562
1563 EXPORT_SYMBOL_GPL(nvmem_cell_write);
1564
1565 static int nvmem_cell_read_common(struct device *dev, const char *cell_id,
1566                                   void *val, size_t count)
1567 {
1568         struct nvmem_cell *cell;
1569         void *buf;
1570         size_t len;
1571
1572         cell = nvmem_cell_get(dev, cell_id);
1573         if (IS_ERR(cell))
1574                 return PTR_ERR(cell);
1575
1576         buf = nvmem_cell_read(cell, &len);
1577         if (IS_ERR(buf)) {
1578                 nvmem_cell_put(cell);
1579                 return PTR_ERR(buf);
1580         }
1581         if (len != count) {
1582                 kfree(buf);
1583                 nvmem_cell_put(cell);
1584                 return -EINVAL;
1585         }
1586         memcpy(val, buf, count);
1587         kfree(buf);
1588         nvmem_cell_put(cell);
1589
1590         return 0;
1591 }
1592
1593 /**
1594  * nvmem_cell_read_u8() - Read a cell value as a u8
1595  *
1596  * @dev: Device that requests the nvmem cell.
1597  * @cell_id: Name of nvmem cell to read.
1598  * @val: pointer to output value.
1599  *
1600  * Return: 0 on success or negative errno.
1601  */
1602 int nvmem_cell_read_u8(struct device *dev, const char *cell_id, u8 *val)
1603 {
1604         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1605 }
1606 EXPORT_SYMBOL_GPL(nvmem_cell_read_u8);
1607
1608 /**
1609  * nvmem_cell_read_u16() - Read a cell value as a u16
1610  *
1611  * @dev: Device that requests the nvmem cell.
1612  * @cell_id: Name of nvmem cell to read.
1613  * @val: pointer to output value.
1614  *
1615  * Return: 0 on success or negative errno.
1616  */
1617 int nvmem_cell_read_u16(struct device *dev, const char *cell_id, u16 *val)
1618 {
1619         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1620 }
1621 EXPORT_SYMBOL_GPL(nvmem_cell_read_u16);
1622
1623 /**
1624  * nvmem_cell_read_u32() - Read a cell value as a u32
1625  *
1626  * @dev: Device that requests the nvmem cell.
1627  * @cell_id: Name of nvmem cell to read.
1628  * @val: pointer to output value.
1629  *
1630  * Return: 0 on success or negative errno.
1631  */
1632 int nvmem_cell_read_u32(struct device *dev, const char *cell_id, u32 *val)
1633 {
1634         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1635 }
1636 EXPORT_SYMBOL_GPL(nvmem_cell_read_u32);
1637
1638 /**
1639  * nvmem_cell_read_u64() - Read a cell value as a u64
1640  *
1641  * @dev: Device that requests the nvmem cell.
1642  * @cell_id: Name of nvmem cell to read.
1643  * @val: pointer to output value.
1644  *
1645  * Return: 0 on success or negative errno.
1646  */
1647 int nvmem_cell_read_u64(struct device *dev, const char *cell_id, u64 *val)
1648 {
1649         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1650 }
1651 EXPORT_SYMBOL_GPL(nvmem_cell_read_u64);
1652
1653 static const void *nvmem_cell_read_variable_common(struct device *dev,
1654                                                    const char *cell_id,
1655                                                    size_t max_len, size_t *len)
1656 {
1657         struct nvmem_cell *cell;
1658         int nbits;
1659         void *buf;
1660
1661         cell = nvmem_cell_get(dev, cell_id);
1662         if (IS_ERR(cell))
1663                 return cell;
1664
1665         nbits = cell->entry->nbits;
1666         buf = nvmem_cell_read(cell, len);
1667         nvmem_cell_put(cell);
1668         if (IS_ERR(buf))
1669                 return buf;
1670
1671         /*
1672          * If nbits is set then nvmem_cell_read() can significantly exaggerate
1673          * the length of the real data. Throw away the extra junk.
1674          */
1675         if (nbits)
1676                 *len = DIV_ROUND_UP(nbits, 8);
1677
1678         if (*len > max_len) {
1679                 kfree(buf);
1680                 return ERR_PTR(-ERANGE);
1681         }
1682
1683         return buf;
1684 }
1685
1686 /**
1687  * nvmem_cell_read_variable_le_u32() - Read up to 32-bits of data as a little endian number.
1688  *
1689  * @dev: Device that requests the nvmem cell.
1690  * @cell_id: Name of nvmem cell to read.
1691  * @val: pointer to output value.
1692  *
1693  * Return: 0 on success or negative errno.
1694  */
1695 int nvmem_cell_read_variable_le_u32(struct device *dev, const char *cell_id,
1696                                     u32 *val)
1697 {
1698         size_t len;
1699         const u8 *buf;
1700         int i;
1701
1702         buf = nvmem_cell_read_variable_common(dev, cell_id, sizeof(*val), &len);
1703         if (IS_ERR(buf))
1704                 return PTR_ERR(buf);
1705
1706         /* Copy w/ implicit endian conversion */
1707         *val = 0;
1708         for (i = 0; i < len; i++)
1709                 *val |= buf[i] << (8 * i);
1710
1711         kfree(buf);
1712
1713         return 0;
1714 }
1715 EXPORT_SYMBOL_GPL(nvmem_cell_read_variable_le_u32);
1716
1717 /**
1718  * nvmem_cell_read_variable_le_u64() - Read up to 64-bits of data as a little endian number.
1719  *
1720  * @dev: Device that requests the nvmem cell.
1721  * @cell_id: Name of nvmem cell to read.
1722  * @val: pointer to output value.
1723  *
1724  * Return: 0 on success or negative errno.
1725  */
1726 int nvmem_cell_read_variable_le_u64(struct device *dev, const char *cell_id,
1727                                     u64 *val)
1728 {
1729         size_t len;
1730         const u8 *buf;
1731         int i;
1732
1733         buf = nvmem_cell_read_variable_common(dev, cell_id, sizeof(*val), &len);
1734         if (IS_ERR(buf))
1735                 return PTR_ERR(buf);
1736
1737         /* Copy w/ implicit endian conversion */
1738         *val = 0;
1739         for (i = 0; i < len; i++)
1740                 *val |= (uint64_t)buf[i] << (8 * i);
1741
1742         kfree(buf);
1743
1744         return 0;
1745 }
1746 EXPORT_SYMBOL_GPL(nvmem_cell_read_variable_le_u64);
1747
1748 /**
1749  * nvmem_device_cell_read() - Read a given nvmem device and cell
1750  *
1751  * @nvmem: nvmem device to read from.
1752  * @info: nvmem cell info to be read.
1753  * @buf: buffer pointer which will be populated on successful read.
1754  *
1755  * Return: length of successful bytes read on success and negative
1756  * error code on error.
1757  */
1758 ssize_t nvmem_device_cell_read(struct nvmem_device *nvmem,
1759                            struct nvmem_cell_info *info, void *buf)
1760 {
1761         struct nvmem_cell_entry cell;
1762         int rc;
1763         ssize_t len;
1764
1765         if (!nvmem)
1766                 return -EINVAL;
1767
1768         rc = nvmem_cell_info_to_nvmem_cell_entry_nodup(nvmem, info, &cell);
1769         if (rc)
1770                 return rc;
1771
1772         rc = __nvmem_cell_read(nvmem, &cell, buf, &len, NULL);
1773         if (rc)
1774                 return rc;
1775
1776         return len;
1777 }
1778 EXPORT_SYMBOL_GPL(nvmem_device_cell_read);
1779
1780 /**
1781  * nvmem_device_cell_write() - Write cell to a given nvmem device
1782  *
1783  * @nvmem: nvmem device to be written to.
1784  * @info: nvmem cell info to be written.
1785  * @buf: buffer to be written to cell.
1786  *
1787  * Return: length of bytes written or negative error code on failure.
1788  */
1789 int nvmem_device_cell_write(struct nvmem_device *nvmem,
1790                             struct nvmem_cell_info *info, void *buf)
1791 {
1792         struct nvmem_cell_entry cell;
1793         int rc;
1794
1795         if (!nvmem)
1796                 return -EINVAL;
1797
1798         rc = nvmem_cell_info_to_nvmem_cell_entry_nodup(nvmem, info, &cell);
1799         if (rc)
1800                 return rc;
1801
1802         return __nvmem_cell_entry_write(&cell, buf, cell.bytes);
1803 }
1804 EXPORT_SYMBOL_GPL(nvmem_device_cell_write);
1805
1806 /**
1807  * nvmem_device_read() - Read from a given nvmem device
1808  *
1809  * @nvmem: nvmem device to read from.
1810  * @offset: offset in nvmem device.
1811  * @bytes: number of bytes to read.
1812  * @buf: buffer pointer which will be populated on successful read.
1813  *
1814  * Return: length of successful bytes read on success and negative
1815  * error code on error.
1816  */
1817 int nvmem_device_read(struct nvmem_device *nvmem,
1818                       unsigned int offset,
1819                       size_t bytes, void *buf)
1820 {
1821         int rc;
1822
1823         if (!nvmem)
1824                 return -EINVAL;
1825
1826         rc = nvmem_reg_read(nvmem, offset, buf, bytes);
1827
1828         if (rc)
1829                 return rc;
1830
1831         return bytes;
1832 }
1833 EXPORT_SYMBOL_GPL(nvmem_device_read);
1834
1835 /**
1836  * nvmem_device_write() - Write cell to a given nvmem device
1837  *
1838  * @nvmem: nvmem device to be written to.
1839  * @offset: offset in nvmem device.
1840  * @bytes: number of bytes to write.
1841  * @buf: buffer to be written.
1842  *
1843  * Return: length of bytes written or negative error code on failure.
1844  */
1845 int nvmem_device_write(struct nvmem_device *nvmem,
1846                        unsigned int offset,
1847                        size_t bytes, void *buf)
1848 {
1849         int rc;
1850
1851         if (!nvmem)
1852                 return -EINVAL;
1853
1854         rc = nvmem_reg_write(nvmem, offset, buf, bytes);
1855
1856         if (rc)
1857                 return rc;
1858
1859
1860         return bytes;
1861 }
1862 EXPORT_SYMBOL_GPL(nvmem_device_write);
1863
1864 /**
1865  * nvmem_add_cell_table() - register a table of cell info entries
1866  *
1867  * @table: table of cell info entries
1868  */
1869 void nvmem_add_cell_table(struct nvmem_cell_table *table)
1870 {
1871         mutex_lock(&nvmem_cell_mutex);
1872         list_add_tail(&table->node, &nvmem_cell_tables);
1873         mutex_unlock(&nvmem_cell_mutex);
1874 }
1875 EXPORT_SYMBOL_GPL(nvmem_add_cell_table);
1876
1877 /**
1878  * nvmem_del_cell_table() - remove a previously registered cell info table
1879  *
1880  * @table: table of cell info entries
1881  */
1882 void nvmem_del_cell_table(struct nvmem_cell_table *table)
1883 {
1884         mutex_lock(&nvmem_cell_mutex);
1885         list_del(&table->node);
1886         mutex_unlock(&nvmem_cell_mutex);
1887 }
1888 EXPORT_SYMBOL_GPL(nvmem_del_cell_table);
1889
1890 /**
1891  * nvmem_add_cell_lookups() - register a list of cell lookup entries
1892  *
1893  * @entries: array of cell lookup entries
1894  * @nentries: number of cell lookup entries in the array
1895  */
1896 void nvmem_add_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
1897 {
1898         int i;
1899
1900         mutex_lock(&nvmem_lookup_mutex);
1901         for (i = 0; i < nentries; i++)
1902                 list_add_tail(&entries[i].node, &nvmem_lookup_list);
1903         mutex_unlock(&nvmem_lookup_mutex);
1904 }
1905 EXPORT_SYMBOL_GPL(nvmem_add_cell_lookups);
1906
1907 /**
1908  * nvmem_del_cell_lookups() - remove a list of previously added cell lookup
1909  *                            entries
1910  *
1911  * @entries: array of cell lookup entries
1912  * @nentries: number of cell lookup entries in the array
1913  */
1914 void nvmem_del_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
1915 {
1916         int i;
1917
1918         mutex_lock(&nvmem_lookup_mutex);
1919         for (i = 0; i < nentries; i++)
1920                 list_del(&entries[i].node);
1921         mutex_unlock(&nvmem_lookup_mutex);
1922 }
1923 EXPORT_SYMBOL_GPL(nvmem_del_cell_lookups);
1924
1925 /**
1926  * nvmem_dev_name() - Get the name of a given nvmem device.
1927  *
1928  * @nvmem: nvmem device.
1929  *
1930  * Return: name of the nvmem device.
1931  */
1932 const char *nvmem_dev_name(struct nvmem_device *nvmem)
1933 {
1934         return dev_name(&nvmem->dev);
1935 }
1936 EXPORT_SYMBOL_GPL(nvmem_dev_name);
1937
1938 static int __init nvmem_init(void)
1939 {
1940         return bus_register(&nvmem_bus_type);
1941 }
1942
1943 static void __exit nvmem_exit(void)
1944 {
1945         bus_unregister(&nvmem_bus_type);
1946 }
1947
1948 subsys_initcall(nvmem_init);
1949 module_exit(nvmem_exit);
1950
1951 MODULE_AUTHOR("Srinivas Kandagatla <srinivas.kandagatla@linaro.org");
1952 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com");
1953 MODULE_DESCRIPTION("nvmem Driver Core");
1954 MODULE_LICENSE("GPL v2");