drivers/nvmem/core.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * nvmem framework core.
   4  *
   5  * Copyright (C) 2015 Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
   6  * Copyright (C) 2013 Maxime Ripard <maxime.ripard@free-electrons.com>
   7  */
   8
   9 #include <linux/device.h>
  10 #include <linux/export.h>
  11 #include <linux/fs.h>
  12 #include <linux/idr.h>
  13 #include <linux/init.h>
  14 #include <linux/kref.h>
  15 #include <linux/module.h>
  16 #include <linux/nvmem-consumer.h>
  17 #include <linux/nvmem-provider.h>
  18 #include <linux/gpio/consumer.h>
  19 #include <linux/of.h>
  20 #include <linux/slab.h>
  21
  22 struct nvmem_device {
  23         struct module           *owner;
  24         struct device           dev;
  25         int                     stride;
  26         int                     word_size;
  27         int                     id;
  28         struct kref             refcnt;
  29         size_t                  size;
  30         bool                    read_only;
  31         bool                    root_only;
  32         int                     flags;
  33         enum nvmem_type         type;
  34         struct bin_attribute    eeprom;
  35         struct device           *base_dev;
  36         struct list_head        cells;
  37         const struct nvmem_keepout *keepout;
  38         unsigned int            nkeepout;
  39         nvmem_reg_read_t        reg_read;
  40         nvmem_reg_write_t       reg_write;
  41         struct gpio_desc        *wp_gpio;
  42         void *priv;
  43 };
  44
  45 #define to_nvmem_device(d) container_of(d, struct nvmem_device, dev)
  46
  47 #define FLAG_COMPAT             BIT(0)
  48
  49 struct nvmem_cell {
  50         const char              *name;
  51         int                     offset;
  52         int                     bytes;
  53         int                     bit_offset;
  54         int                     nbits;
  55         struct device_node      *np;
  56         struct nvmem_device     *nvmem;
  57         struct list_head        node;
  58 };
  59
  60 static DEFINE_MUTEX(nvmem_mutex);
  61 static DEFINE_IDA(nvmem_ida);
  62
  63 static DEFINE_MUTEX(nvmem_cell_mutex);
  64 static LIST_HEAD(nvmem_cell_tables);
  65
  66 static DEFINE_MUTEX(nvmem_lookup_mutex);
  67 static LIST_HEAD(nvmem_lookup_list);
  68
  69 static BLOCKING_NOTIFIER_HEAD(nvmem_notifier);
  70
  71 static int __nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
  72                             void *val, size_t bytes)
  73 {
  74         if (nvmem->reg_read)
  75                 return nvmem->reg_read(nvmem->priv, offset, val, bytes);
  76
  77         return -EINVAL;
  78 }
  79
  80 static int __nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
  81                              void *val, size_t bytes)
  82 {
  83         int ret;
  84
  85         if (nvmem->reg_write) {
  86                 gpiod_set_value_cansleep(nvmem->wp_gpio, 0);
  87                 ret = nvmem->reg_write(nvmem->priv, offset, val, bytes);
  88                 gpiod_set_value_cansleep(nvmem->wp_gpio, 1);
  89                 return ret;
  90         }
  91
  92         return -EINVAL;
  93 }
  94
  95 static int nvmem_access_with_keepouts(struct nvmem_device *nvmem,
  96                                       unsigned int offset, void *val,
  97                                       size_t bytes, int write)
  98 {
  99
 100         unsigned int end = offset + bytes;
 101         unsigned int kend, ksize;
 102         const struct nvmem_keepout *keepout = nvmem->keepout;
 103         const struct nvmem_keepout *keepoutend = keepout + nvmem->nkeepout;
 104         int rc;
 105
 106         /*
 107          * Skip all keepouts before the range being accessed.
 108          * Keepouts are sorted.
 109          */
 110         while ((keepout < keepoutend) && (keepout->end <= offset))
 111                 keepout++;
 112
 113         while ((offset < end) && (keepout < keepoutend)) {
 114                 /* Access the valid portion before the keepout. */
 115                 if (offset < keepout->start) {
 116                         kend = min(end, keepout->start);
 117                         ksize = kend - offset;
 118                         if (write)
 119                                 rc = __nvmem_reg_write(nvmem, offset, val, ksize);
 120                         else
 121                                 rc = __nvmem_reg_read(nvmem, offset, val, ksize);
 122
 123                         if (rc)
 124                                 return rc;
 125
 126                         offset += ksize;
 127                         val += ksize;
 128                 }
 129
 130                 /*
 131                  * Now we're aligned to the start of this keepout zone. Go
 132                  * through it.
 133                  */
 134                 kend = min(end, keepout->end);
 135                 ksize = kend - offset;
 136                 if (!write)
 137                         memset(val, keepout->value, ksize);
 138
 139                 val += ksize;
 140                 offset += ksize;
 141                 keepout++;
 142         }
 143
 144         /*
 145          * If we ran out of keepouts but there's still stuff to do, send it
 146          * down directly
 147          */
 148         if (offset < end) {
 149                 ksize = end - offset;
 150                 if (write)
 151                         return __nvmem_reg_write(nvmem, offset, val, ksize);
 152                 else
 153                         return __nvmem_reg_read(nvmem, offset, val, ksize);
 154         }
 155
 156         return 0;
 157 }
 158
 159 static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
 160                           void *val, size_t bytes)
 161 {
 162         if (!nvmem->nkeepout)
 163                 return __nvmem_reg_read(nvmem, offset, val, bytes);
 164
 165         return nvmem_access_with_keepouts(nvmem, offset, val, bytes, false);
 166 }
 167
 168 static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
 169                            void *val, size_t bytes)
 170 {
 171         if (!nvmem->nkeepout)
 172                 return __nvmem_reg_write(nvmem, offset, val, bytes);
 173
 174         return nvmem_access_with_keepouts(nvmem, offset, val, bytes, true);
 175 }
 176
 177 #ifdef CONFIG_NVMEM_SYSFS
 178 static const char * const nvmem_type_str[] = {
 179         [NVMEM_TYPE_UNKNOWN] = "Unknown",
 180         [NVMEM_TYPE_EEPROM] = "EEPROM",
 181         [NVMEM_TYPE_OTP] = "OTP",
 182         [NVMEM_TYPE_BATTERY_BACKED] = "Battery backed",
 183         [NVMEM_TYPE_FRAM] = "FRAM",
 184 };
 185
 186 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 187 static struct lock_class_key eeprom_lock_key;
 188 #endif
 189
 190 static ssize_t type_show(struct device *dev,
 191                          struct device_attribute *attr, char *buf)
 192 {
 193         struct nvmem_device *nvmem = to_nvmem_device(dev);
 194
 195         return sprintf(buf, "%s\n", nvmem_type_str[nvmem->type]);
 196 }
 197
 198 static DEVICE_ATTR_RO(type);
 199
 200 static struct attribute *nvmem_attrs[] = {
 201         &dev_attr_type.attr,
 202         NULL,
 203 };
 204
 205 static ssize_t bin_attr_nvmem_read(struct file *filp, struct kobject *kobj,
 206                                    struct bin_attribute *attr, char *buf,
 207                                    loff_t pos, size_t count)
 208 {
 209         struct device *dev;
 210         struct nvmem_device *nvmem;
 211         int rc;
 212
 213         if (attr->private)
 214                 dev = attr->private;
 215         else
 216                 dev = kobj_to_dev(kobj);
 217         nvmem = to_nvmem_device(dev);
 218
 219         /* Stop the user from reading */
 220         if (pos >= nvmem->size)
 221                 return 0;
 222
 223         if (!IS_ALIGNED(pos, nvmem->stride))
 224                 return -EINVAL;
 225
 226         if (count < nvmem->word_size)
 227                 return -EINVAL;
 228
 229         if (pos + count > nvmem->size)
 230                 count = nvmem->size - pos;
 231
 232         count = round_down(count, nvmem->word_size);
 233
 234         if (!nvmem->reg_read)
 235                 return -EPERM;
 236
 237         rc = nvmem_reg_read(nvmem, pos, buf, count);
 238
 239         if (rc)
 240                 return rc;
 241
 242         return count;
 243 }
 244
 245 static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj,
 246                                     struct bin_attribute *attr, char *buf,
 247                                     loff_t pos, size_t count)
 248 {
 249         struct device *dev;
 250         struct nvmem_device *nvmem;
 251         int rc;
 252
 253         if (attr->private)
 254                 dev = attr->private;
 255         else
 256                 dev = kobj_to_dev(kobj);
 257         nvmem = to_nvmem_device(dev);
 258
 259         /* Stop the user from writing */
 260         if (pos >= nvmem->size)
 261                 return -EFBIG;
 262
 263         if (!IS_ALIGNED(pos, nvmem->stride))
 264                 return -EINVAL;
 265
 266         if (count < nvmem->word_size)
 267                 return -EINVAL;
 268
 269         if (pos + count > nvmem->size)
 270                 count = nvmem->size - pos;
 271
 272         count = round_down(count, nvmem->word_size);
 273
 274         if (!nvmem->reg_write)
 275                 return -EPERM;
 276
 277         rc = nvmem_reg_write(nvmem, pos, buf, count);
 278
 279         if (rc)
 280                 return rc;
 281
 282         return count;
 283 }
 284
 285 static umode_t nvmem_bin_attr_get_umode(struct nvmem_device *nvmem)
 286 {
 287         umode_t mode = 0400;
 288
 289         if (!nvmem->root_only)
 290                 mode |= 0044;
 291
 292         if (!nvmem->read_only)
 293                 mode |= 0200;
 294
 295         if (!nvmem->reg_write)
 296                 mode &= ~0200;
 297
 298         if (!nvmem->reg_read)
 299                 mode &= ~0444;
 300
 301         return mode;
 302 }
 303
 304 static umode_t nvmem_bin_attr_is_visible(struct kobject *kobj,
 305                                          struct bin_attribute *attr, int i)
 306 {
 307         struct device *dev = kobj_to_dev(kobj);
 308         struct nvmem_device *nvmem = to_nvmem_device(dev);
 309
 310         return nvmem_bin_attr_get_umode(nvmem);
 311 }
 312
 313 /* default read/write permissions */
 314 static struct bin_attribute bin_attr_rw_nvmem = {
 315         .attr   = {
 316                 .name   = "nvmem",
 317                 .mode   = 0644,
 318         },
 319         .read   = bin_attr_nvmem_read,
 320         .write  = bin_attr_nvmem_write,
 321 };
 322
 323 static struct bin_attribute *nvmem_bin_attributes[] = {
 324         &bin_attr_rw_nvmem,
 325         NULL,
 326 };
 327
 328 static const struct attribute_group nvmem_bin_group = {
 329         .bin_attrs      = nvmem_bin_attributes,
 330         .attrs          = nvmem_attrs,
 331         .is_bin_visible = nvmem_bin_attr_is_visible,
 332 };
 333
 334 static const struct attribute_group *nvmem_dev_groups[] = {
 335         &nvmem_bin_group,
 336         NULL,
 337 };
 338
 339 static struct bin_attribute bin_attr_nvmem_eeprom_compat = {
 340         .attr   = {
 341                 .name   = "eeprom",
 342         },
 343         .read   = bin_attr_nvmem_read,
 344         .write  = bin_attr_nvmem_write,
 345 };
 346
 347 /*
 348  * nvmem_setup_compat() - Create an additional binary entry in
 349  * drivers sys directory, to be backwards compatible with the older
 350  * drivers/misc/eeprom drivers.
 351  */
 352 static int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
 353                                     const struct nvmem_config *config)
 354 {
 355         int rval;
 356
 357         if (!config->compat)
 358                 return 0;
 359
 360         if (!config->base_dev)
 361                 return -EINVAL;
 362
 363         if (config->type == NVMEM_TYPE_FRAM)
 364                 bin_attr_nvmem_eeprom_compat.attr.name = "fram";
 365
 366         nvmem->eeprom = bin_attr_nvmem_eeprom_compat;
 367         nvmem->eeprom.attr.mode = nvmem_bin_attr_get_umode(nvmem);
 368         nvmem->eeprom.size = nvmem->size;
 369 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 370         nvmem->eeprom.attr.key = &eeprom_lock_key;
 371 #endif
 372         nvmem->eeprom.private = &nvmem->dev;
 373         nvmem->base_dev = config->base_dev;
 374
 375         rval = device_create_bin_file(nvmem->base_dev, &nvmem->eeprom);
 376         if (rval) {
 377                 dev_err(&nvmem->dev,
 378                         "Failed to create eeprom binary file %d\n", rval);
 379                 return rval;
 380         }
 381
 382         nvmem->flags |= FLAG_COMPAT;
 383
 384         return 0;
 385 }
 386
 387 static void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem,
 388                               const struct nvmem_config *config)
 389 {
 390         if (config->compat)
 391                 device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
 392 }
 393
 394 #else /* CONFIG_NVMEM_SYSFS */
 395
 396 static int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
 397                                     const struct nvmem_config *config)
 398 {
 399         return -ENOSYS;
 400 }
 401 static void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem,
 402                                       const struct nvmem_config *config)
 403 {
 404 }
 405
 406 #endif /* CONFIG_NVMEM_SYSFS */
 407
 408 static void nvmem_release(struct device *dev)
 409 {
 410         struct nvmem_device *nvmem = to_nvmem_device(dev);
 411
 412         ida_free(&nvmem_ida, nvmem->id);
 413         gpiod_put(nvmem->wp_gpio);
 414         kfree(nvmem);
 415 }
 416
 417 static const struct device_type nvmem_provider_type = {
 418         .release        = nvmem_release,
 419 };
 420
 421 static struct bus_type nvmem_bus_type = {
 422         .name           = "nvmem",
 423 };
 424
 425 static void nvmem_cell_drop(struct nvmem_cell *cell)
 426 {
 427         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_REMOVE, cell);
 428         mutex_lock(&nvmem_mutex);
 429         list_del(&cell->node);
 430         mutex_unlock(&nvmem_mutex);
 431         of_node_put(cell->np);
 432         kfree_const(cell->name);
 433         kfree(cell);
 434 }
 435
 436 static void nvmem_device_remove_all_cells(const struct nvmem_device *nvmem)
 437 {
 438         struct nvmem_cell *cell, *p;
 439
 440         list_for_each_entry_safe(cell, p, &nvmem->cells, node)
 441                 nvmem_cell_drop(cell);
 442 }
 443
 444 static void nvmem_cell_add(struct nvmem_cell *cell)
 445 {
 446         mutex_lock(&nvmem_mutex);
 447         list_add_tail(&cell->node, &cell->nvmem->cells);
 448         mutex_unlock(&nvmem_mutex);
 449         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_ADD, cell);
 450 }
 451
 452 static int nvmem_cell_info_to_nvmem_cell_nodup(struct nvmem_device *nvmem,
 453                                         const struct nvmem_cell_info *info,
 454                                         struct nvmem_cell *cell)
 455 {
 456         cell->nvmem = nvmem;
 457         cell->offset = info->offset;
 458         cell->bytes = info->bytes;
 459         cell->name = info->name;
 460
 461         cell->bit_offset = info->bit_offset;
 462         cell->nbits = info->nbits;
 463
 464         if (cell->nbits)
 465                 cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
 466                                            BITS_PER_BYTE);
 467
 468         if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
 469                 dev_err(&nvmem->dev,
 470                         "cell %s unaligned to nvmem stride %d\n",
 471                         cell->name ?: "<unknown>", nvmem->stride);
 472                 return -EINVAL;
 473         }
 474
 475         return 0;
 476 }
 477
 478 static int nvmem_cell_info_to_nvmem_cell(struct nvmem_device *nvmem,
 479                                 const struct nvmem_cell_info *info,
 480                                 struct nvmem_cell *cell)
 481 {
 482         int err;
 483
 484         err = nvmem_cell_info_to_nvmem_cell_nodup(nvmem, info, cell);
 485         if (err)
 486                 return err;
 487
 488         cell->name = kstrdup_const(info->name, GFP_KERNEL);
 489         if (!cell->name)
 490                 return -ENOMEM;
 491
 492         return 0;
 493 }
 494
 495 /**
 496  * nvmem_add_cells() - Add cell information to an nvmem device
 497  *
 498  * @nvmem: nvmem device to add cells to.
 499  * @info: nvmem cell info to add to the device
 500  * @ncells: number of cells in info
 501  *
 502  * Return: 0 or negative error code on failure.
 503  */
 504 static int nvmem_add_cells(struct nvmem_device *nvmem,
 505                     const struct nvmem_cell_info *info,
 506                     int ncells)
 507 {
 508         struct nvmem_cell **cells;
 509         int i, rval;
 510
 511         cells = kcalloc(ncells, sizeof(*cells), GFP_KERNEL);
 512         if (!cells)
 513                 return -ENOMEM;
 514
 515         for (i = 0; i < ncells; i++) {
 516                 cells[i] = kzalloc(sizeof(**cells), GFP_KERNEL);
 517                 if (!cells[i]) {
 518                         rval = -ENOMEM;
 519                         goto err;
 520                 }
 521
 522                 rval = nvmem_cell_info_to_nvmem_cell(nvmem, &info[i], cells[i]);
 523                 if (rval) {
 524                         kfree(cells[i]);
 525                         goto err;
 526                 }
 527
 528                 nvmem_cell_add(cells[i]);
 529         }
 530
 531         /* remove tmp array */
 532         kfree(cells);
 533
 534         return 0;
 535 err:
 536         while (i--)
 537                 nvmem_cell_drop(cells[i]);
 538
 539         kfree(cells);
 540
 541         return rval;
 542 }
 543
 544 /**
 545  * nvmem_register_notifier() - Register a notifier block for nvmem events.
 546  *
 547  * @nb: notifier block to be called on nvmem events.
 548  *
 549  * Return: 0 on success, negative error number on failure.
 550  */
 551 int nvmem_register_notifier(struct notifier_block *nb)
 552 {
 553         return blocking_notifier_chain_register(&nvmem_notifier, nb);
 554 }
 555 EXPORT_SYMBOL_GPL(nvmem_register_notifier);
 556
 557 /**
 558  * nvmem_unregister_notifier() - Unregister a notifier block for nvmem events.
 559  *
 560  * @nb: notifier block to be unregistered.
 561  *
 562  * Return: 0 on success, negative error number on failure.
 563  */
 564 int nvmem_unregister_notifier(struct notifier_block *nb)
 565 {
 566         return blocking_notifier_chain_unregister(&nvmem_notifier, nb);
 567 }
 568 EXPORT_SYMBOL_GPL(nvmem_unregister_notifier);
 569
 570 static int nvmem_add_cells_from_table(struct nvmem_device *nvmem)
 571 {
 572         const struct nvmem_cell_info *info;
 573         struct nvmem_cell_table *table;
 574         struct nvmem_cell *cell;
 575         int rval = 0, i;
 576
 577         mutex_lock(&nvmem_cell_mutex);
 578         list_for_each_entry(table, &nvmem_cell_tables, node) {
 579                 if (strcmp(nvmem_dev_name(nvmem), table->nvmem_name) == 0) {
 580                         for (i = 0; i < table->ncells; i++) {
 581                                 info = &table->cells[i];
 582
 583                                 cell = kzalloc(sizeof(*cell), GFP_KERNEL);
 584                                 if (!cell) {
 585                                         rval = -ENOMEM;
 586                                         goto out;
 587                                 }
 588
 589                                 rval = nvmem_cell_info_to_nvmem_cell(nvmem,
 590                                                                      info,
 591                                                                      cell);
 592                                 if (rval) {
 593                                         kfree(cell);
 594                                         goto out;
 595                                 }
 596
 597                                 nvmem_cell_add(cell);
 598                         }
 599                 }
 600         }
 601
 602 out:
 603         mutex_unlock(&nvmem_cell_mutex);
 604         return rval;
 605 }
 606
 607 static struct nvmem_cell *
 608 nvmem_find_cell_by_name(struct nvmem_device *nvmem, const char *cell_id)
 609 {
 610         struct nvmem_cell *iter, *cell = NULL;
 611
 612         mutex_lock(&nvmem_mutex);
 613         list_for_each_entry(iter, &nvmem->cells, node) {
 614                 if (strcmp(cell_id, iter->name) == 0) {
 615                         cell = iter;
 616                         break;
 617                 }
 618         }
 619         mutex_unlock(&nvmem_mutex);
 620
 621         return cell;
 622 }
 623
 624 static int nvmem_validate_keepouts(struct nvmem_device *nvmem)
 625 {
 626         unsigned int cur = 0;
 627         const struct nvmem_keepout *keepout = nvmem->keepout;
 628         const struct nvmem_keepout *keepoutend = keepout + nvmem->nkeepout;
 629
 630         while (keepout < keepoutend) {
 631                 /* Ensure keepouts are sorted and don't overlap. */
 632                 if (keepout->start < cur) {
 633                         dev_err(&nvmem->dev,
 634                                 "Keepout regions aren't sorted or overlap.\n");
 635
 636                         return -ERANGE;
 637                 }
 638
 639                 if (keepout->end < keepout->start) {
 640                         dev_err(&nvmem->dev,
 641                                 "Invalid keepout region.\n");
 642
 643                         return -EINVAL;
 644                 }
 645
 646                 /*
 647                  * Validate keepouts (and holes between) don't violate
 648                  * word_size constraints.
 649                  */
 650                 if ((keepout->end - keepout->start < nvmem->word_size) ||
 651                     ((keepout->start != cur) &&
 652                      (keepout->start - cur < nvmem->word_size))) {
 653
 654                         dev_err(&nvmem->dev,
 655                                 "Keepout regions violate word_size constraints.\n");
 656
 657                         return -ERANGE;
 658                 }
 659
 660                 /* Validate keepouts don't violate stride (alignment). */
 661                 if (!IS_ALIGNED(keepout->start, nvmem->stride) ||
 662                     !IS_ALIGNED(keepout->end, nvmem->stride)) {
 663
 664                         dev_err(&nvmem->dev,
 665                                 "Keepout regions violate stride.\n");
 666
 667                         return -EINVAL;
 668                 }
 669
 670                 cur = keepout->end;
 671                 keepout++;
 672         }
 673
 674         return 0;
 675 }
 676
 677 static int nvmem_add_cells_from_of(struct nvmem_device *nvmem)
 678 {
 679         struct device_node *parent, *child;
 680         struct device *dev = &nvmem->dev;
 681         struct nvmem_cell *cell;
 682         const __be32 *addr;
 683         int len;
 684
 685         parent = dev->of_node;
 686
 687         for_each_child_of_node(parent, child) {
 688                 addr = of_get_property(child, "reg", &len);
 689                 if (!addr)
 690                         continue;
 691                 if (len < 2 * sizeof(u32)) {
 692                         dev_err(dev, "nvmem: invalid reg on %pOF\n", child);
 693                         of_node_put(child);
 694                         return -EINVAL;
 695                 }
 696
 697                 cell = kzalloc(sizeof(*cell), GFP_KERNEL);
 698                 if (!cell) {
 699                         of_node_put(child);
 700                         return -ENOMEM;
 701                 }
 702
 703                 cell->nvmem = nvmem;
 704                 cell->offset = be32_to_cpup(addr++);
 705                 cell->bytes = be32_to_cpup(addr);
 706                 cell->name = kasprintf(GFP_KERNEL, "%pOFn", child);
 707
 708                 addr = of_get_property(child, "bits", &len);
 709                 if (addr && len == (2 * sizeof(u32))) {
 710                         cell->bit_offset = be32_to_cpup(addr++);
 711                         cell->nbits = be32_to_cpup(addr);
 712                 }
 713
 714                 if (cell->nbits)
 715                         cell->bytes = DIV_ROUND_UP(
 716                                         cell->nbits + cell->bit_offset,
 717                                         BITS_PER_BYTE);
 718
 719                 if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
 720                         dev_err(dev, "cell %s unaligned to nvmem stride %d\n",
 721                                 cell->name, nvmem->stride);
 722                         /* Cells already added will be freed later. */
 723                         kfree_const(cell->name);
 724                         kfree(cell);
 725                         of_node_put(child);
 726                         return -EINVAL;
 727                 }
 728
 729                 cell->np = of_node_get(child);
 730                 nvmem_cell_add(cell);
 731         }
 732
 733         return 0;
 734 }
 735
 736 /**
 737  * nvmem_register() - Register a nvmem device for given nvmem_config.
 738  * Also creates a binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
 739  *
 740  * @config: nvmem device configuration with which nvmem device is created.
 741  *
 742  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
 743  * on success.
 744  */
 745
 746 struct nvmem_device *nvmem_register(const struct nvmem_config *config)
 747 {
 748         struct nvmem_device *nvmem;
 749         int rval;
 750
 751         if (!config->dev)
 752                 return ERR_PTR(-EINVAL);
 753
 754         if (!config->reg_read && !config->reg_write)
 755                 return ERR_PTR(-EINVAL);
 756
 757         nvmem = kzalloc(sizeof(*nvmem), GFP_KERNEL);
 758         if (!nvmem)
 759                 return ERR_PTR(-ENOMEM);
 760
 761         rval  = ida_alloc(&nvmem_ida, GFP_KERNEL);
 762         if (rval < 0) {
 763                 kfree(nvmem);
 764                 return ERR_PTR(rval);
 765         }
 766
 767         if (config->wp_gpio)
 768                 nvmem->wp_gpio = config->wp_gpio;
 769         else
 770                 nvmem->wp_gpio = gpiod_get_optional(config->dev, "wp",
 771                                                     GPIOD_OUT_HIGH);
 772         if (IS_ERR(nvmem->wp_gpio)) {
 773                 ida_free(&nvmem_ida, nvmem->id);
 774                 rval = PTR_ERR(nvmem->wp_gpio);
 775                 kfree(nvmem);
 776                 return ERR_PTR(rval);
 777         }
 778
 779         kref_init(&nvmem->refcnt);
 780         INIT_LIST_HEAD(&nvmem->cells);
 781
 782         nvmem->id = rval;
 783         nvmem->owner = config->owner;
 784         if (!nvmem->owner && config->dev->driver)
 785                 nvmem->owner = config->dev->driver->owner;
 786         nvmem->stride = config->stride ?: 1;
 787         nvmem->word_size = config->word_size ?: 1;
 788         nvmem->size = config->size;
 789         nvmem->dev.type = &nvmem_provider_type;
 790         nvmem->dev.bus = &nvmem_bus_type;
 791         nvmem->dev.parent = config->dev;
 792         nvmem->root_only = config->root_only;
 793         nvmem->priv = config->priv;
 794         nvmem->type = config->type;
 795         nvmem->reg_read = config->reg_read;
 796         nvmem->reg_write = config->reg_write;
 797         nvmem->keepout = config->keepout;
 798         nvmem->nkeepout = config->nkeepout;
 799         if (config->of_node)
 800                 nvmem->dev.of_node = config->of_node;
 801         else if (!config->no_of_node)
 802                 nvmem->dev.of_node = config->dev->of_node;
 803
 804         switch (config->id) {
 805         case NVMEM_DEVID_NONE:
 806                 dev_set_name(&nvmem->dev, "%s", config->name);
 807                 break;
 808         case NVMEM_DEVID_AUTO:
 809                 dev_set_name(&nvmem->dev, "%s%d", config->name, nvmem->id);
 810                 break;
 811         default:
 812                 dev_set_name(&nvmem->dev, "%s%d",
 813                              config->name ? : "nvmem",
 814                              config->name ? config->id : nvmem->id);
 815                 break;
 816         }
 817
 818         nvmem->read_only = device_property_present(config->dev, "read-only") ||
 819                            config->read_only || !nvmem->reg_write;
 820
 821 #ifdef CONFIG_NVMEM_SYSFS
 822         nvmem->dev.groups = nvmem_dev_groups;
 823 #endif
 824
 825         if (nvmem->nkeepout) {
 826                 rval = nvmem_validate_keepouts(nvmem);
 827                 if (rval)
 828                         goto err_put_device;
 829         }
 830
 831         dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
 832
 833         rval = device_register(&nvmem->dev);
 834         if (rval)
 835                 goto err_put_device;
 836
 837         if (config->compat) {
 838                 rval = nvmem_sysfs_setup_compat(nvmem, config);
 839                 if (rval)
 840                         goto err_device_del;
 841         }
 842
 843         if (config->cells) {
 844                 rval = nvmem_add_cells(nvmem, config->cells, config->ncells);
 845                 if (rval)
 846                         goto err_teardown_compat;
 847         }
 848
 849         rval = nvmem_add_cells_from_table(nvmem);
 850         if (rval)
 851                 goto err_remove_cells;
 852
 853         rval = nvmem_add_cells_from_of(nvmem);
 854         if (rval)
 855                 goto err_remove_cells;
 856
 857         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem);
 858
 859         return nvmem;
 860
 861 err_remove_cells:
 862         nvmem_device_remove_all_cells(nvmem);
 863 err_teardown_compat:
 864         if (config->compat)
 865                 nvmem_sysfs_remove_compat(nvmem, config);
 866 err_device_del:
 867         device_del(&nvmem->dev);
 868 err_put_device:
 869         put_device(&nvmem->dev);
 870
 871         return ERR_PTR(rval);
 872 }
 873 EXPORT_SYMBOL_GPL(nvmem_register);
 874
 875 static void nvmem_device_release(struct kref *kref)
 876 {
 877         struct nvmem_device *nvmem;
 878
 879         nvmem = container_of(kref, struct nvmem_device, refcnt);
 880
 881         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_REMOVE, nvmem);
 882
 883         if (nvmem->flags & FLAG_COMPAT)
 884                 device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
 885
 886         nvmem_device_remove_all_cells(nvmem);
 887         device_unregister(&nvmem->dev);
 888 }
 889
 890 /**
 891  * nvmem_unregister() - Unregister previously registered nvmem device
 892  *
 893  * @nvmem: Pointer to previously registered nvmem device.
 894  */
 895 void nvmem_unregister(struct nvmem_device *nvmem)
 896 {
 897         kref_put(&nvmem->refcnt, nvmem_device_release);
 898 }
 899 EXPORT_SYMBOL_GPL(nvmem_unregister);
 900
 901 static void devm_nvmem_release(struct device *dev, void *res)
 902 {
 903         nvmem_unregister(*(struct nvmem_device **)res);
 904 }
 905
 906 /**
 907  * devm_nvmem_register() - Register a managed nvmem device for given
 908  * nvmem_config.
 909  * Also creates a binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
 910  *
 911  * @dev: Device that uses the nvmem device.
 912  * @config: nvmem device configuration with which nvmem device is created.
 913  *
 914  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
 915  * on success.
 916  */
 917 struct nvmem_device *devm_nvmem_register(struct device *dev,
 918                                          const struct nvmem_config *config)
 919 {
 920         struct nvmem_device **ptr, *nvmem;
 921
 922         ptr = devres_alloc(devm_nvmem_release, sizeof(*ptr), GFP_KERNEL);
 923         if (!ptr)
 924                 return ERR_PTR(-ENOMEM);
 925
 926         nvmem = nvmem_register(config);
 927
 928         if (!IS_ERR(nvmem)) {
 929                 *ptr = nvmem;
 930                 devres_add(dev, ptr);
 931         } else {
 932                 devres_free(ptr);
 933         }
 934
 935         return nvmem;
 936 }
 937 EXPORT_SYMBOL_GPL(devm_nvmem_register);
 938
 939 static int devm_nvmem_match(struct device *dev, void *res, void *data)
 940 {
 941         struct nvmem_device **r = res;
 942
 943         return *r == data;
 944 }
 945
 946 /**
 947  * devm_nvmem_unregister() - Unregister previously registered managed nvmem
 948  * device.
 949  *
 950  * @dev: Device that uses the nvmem device.
 951  * @nvmem: Pointer to previously registered nvmem device.
 952  *
 953  * Return: Will be negative on error or zero on success.
 954  */
 955 int devm_nvmem_unregister(struct device *dev, struct nvmem_device *nvmem)
 956 {
 957         return devres_release(dev, devm_nvmem_release, devm_nvmem_match, nvmem);
 958 }
 959 EXPORT_SYMBOL(devm_nvmem_unregister);
 960
 961 static struct nvmem_device *__nvmem_device_get(void *data,
 962                         int (*match)(struct device *dev, const void *data))
 963 {
 964         struct nvmem_device *nvmem = NULL;
 965         struct device *dev;
 966
 967         mutex_lock(&nvmem_mutex);
 968         dev = bus_find_device(&nvmem_bus_type, NULL, data, match);
 969         if (dev)
 970                 nvmem = to_nvmem_device(dev);
 971         mutex_unlock(&nvmem_mutex);
 972         if (!nvmem)
 973                 return ERR_PTR(-EPROBE_DEFER);
 974
 975         if (!try_module_get(nvmem->owner)) {
 976                 dev_err(&nvmem->dev,
 977                         "could not increase module refcount for cell %s\n",
 978                         nvmem_dev_name(nvmem));
 979
 980                 put_device(&nvmem->dev);
 981                 return ERR_PTR(-EINVAL);
 982         }
 983
 984         kref_get(&nvmem->refcnt);
 985
 986         return nvmem;
 987 }
 988
 989 static void __nvmem_device_put(struct nvmem_device *nvmem)
 990 {
 991         put_device(&nvmem->dev);
 992         module_put(nvmem->owner);
 993         kref_put(&nvmem->refcnt, nvmem_device_release);
 994 }
 995
 996 #if IS_ENABLED(CONFIG_OF)
 997 /**
 998  * of_nvmem_device_get() - Get nvmem device from a given id
 999  *
1000  * @np: Device tree node that uses the nvmem device.
1001  * @id: nvmem name from nvmem-names property.
1002  *
1003  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1004  * on success.
1005  */
1006 struct nvmem_device *of_nvmem_device_get(struct device_node *np, const char *id)
1007 {
1008
1009         struct device_node *nvmem_np;
1010         struct nvmem_device *nvmem;
1011         int index = 0;
1012
1013         if (id)
1014                 index = of_property_match_string(np, "nvmem-names", id);
1015
1016         nvmem_np = of_parse_phandle(np, "nvmem", index);
1017         if (!nvmem_np)
1018                 return ERR_PTR(-ENOENT);
1019
1020         nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
1021         of_node_put(nvmem_np);
1022         return nvmem;
1023 }
1024 EXPORT_SYMBOL_GPL(of_nvmem_device_get);
1025 #endif
1026
1027 /**
1028  * nvmem_device_get() - Get nvmem device from a given id
1029  *
1030  * @dev: Device that uses the nvmem device.
1031  * @dev_name: name of the requested nvmem device.
1032  *
1033  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1034  * on success.
1035  */
1036 struct nvmem_device *nvmem_device_get(struct device *dev, const char *dev_name)
1037 {
1038         if (dev->of_node) { /* try dt first */
1039                 struct nvmem_device *nvmem;
1040
1041                 nvmem = of_nvmem_device_get(dev->of_node, dev_name);
1042
1043                 if (!IS_ERR(nvmem) || PTR_ERR(nvmem) == -EPROBE_DEFER)
1044                         return nvmem;
1045
1046         }
1047
1048         return __nvmem_device_get((void *)dev_name, device_match_name);
1049 }
1050 EXPORT_SYMBOL_GPL(nvmem_device_get);
1051
1052 /**
1053  * nvmem_device_find() - Find nvmem device with matching function
1054  *
1055  * @data: Data to pass to match function
1056  * @match: Callback function to check device
1057  *
1058  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1059  * on success.
1060  */
1061 struct nvmem_device *nvmem_device_find(void *data,
1062                         int (*match)(struct device *dev, const void *data))
1063 {
1064         return __nvmem_device_get(data, match);
1065 }
1066 EXPORT_SYMBOL_GPL(nvmem_device_find);
1067
1068 static int devm_nvmem_device_match(struct device *dev, void *res, void *data)
1069 {
1070         struct nvmem_device **nvmem = res;
1071
1072         if (WARN_ON(!nvmem || !*nvmem))
1073                 return 0;
1074
1075         return *nvmem == data;
1076 }
1077
1078 static void devm_nvmem_device_release(struct device *dev, void *res)
1079 {
1080         nvmem_device_put(*(struct nvmem_device **)res);
1081 }
1082
1083 /**
1084  * devm_nvmem_device_put() - put alredy got nvmem device
1085  *
1086  * @dev: Device that uses the nvmem device.
1087  * @nvmem: pointer to nvmem device allocated by devm_nvmem_cell_get(),
1088  * that needs to be released.
1089  */
1090 void devm_nvmem_device_put(struct device *dev, struct nvmem_device *nvmem)
1091 {
1092         int ret;
1093
1094         ret = devres_release(dev, devm_nvmem_device_release,
1095                              devm_nvmem_device_match, nvmem);
1096
1097         WARN_ON(ret);
1098 }
1099 EXPORT_SYMBOL_GPL(devm_nvmem_device_put);
1100
1101 /**
1102  * nvmem_device_put() - put alredy got nvmem device
1103  *
1104  * @nvmem: pointer to nvmem device that needs to be released.
1105  */
1106 void nvmem_device_put(struct nvmem_device *nvmem)
1107 {
1108         __nvmem_device_put(nvmem);
1109 }
1110 EXPORT_SYMBOL_GPL(nvmem_device_put);
1111
1112 /**
1113  * devm_nvmem_device_get() - Get nvmem cell of device form a given id
1114  *
1115  * @dev: Device that requests the nvmem device.
1116  * @id: name id for the requested nvmem device.
1117  *
1118  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_cell
1119  * on success.  The nvmem_cell will be freed by the automatically once the
1120  * device is freed.
1121  */
1122 struct nvmem_device *devm_nvmem_device_get(struct device *dev, const char *id)
1123 {
1124         struct nvmem_device **ptr, *nvmem;
1125
1126         ptr = devres_alloc(devm_nvmem_device_release, sizeof(*ptr), GFP_KERNEL);
1127         if (!ptr)
1128                 return ERR_PTR(-ENOMEM);
1129
1130         nvmem = nvmem_device_get(dev, id);
1131         if (!IS_ERR(nvmem)) {
1132                 *ptr = nvmem;
1133                 devres_add(dev, ptr);
1134         } else {
1135                 devres_free(ptr);
1136         }
1137
1138         return nvmem;
1139 }
1140 EXPORT_SYMBOL_GPL(devm_nvmem_device_get);
1141
1142 static struct nvmem_cell *
1143 nvmem_cell_get_from_lookup(struct device *dev, const char *con_id)
1144 {
1145         struct nvmem_cell *cell = ERR_PTR(-ENOENT);
1146         struct nvmem_cell_lookup *lookup;
1147         struct nvmem_device *nvmem;
1148         const char *dev_id;
1149
1150         if (!dev)
1151                 return ERR_PTR(-EINVAL);
1152
1153         dev_id = dev_name(dev);
1154
1155         mutex_lock(&nvmem_lookup_mutex);
1156
1157         list_for_each_entry(lookup, &nvmem_lookup_list, node) {
1158                 if ((strcmp(lookup->dev_id, dev_id) == 0) &&
1159                     (strcmp(lookup->con_id, con_id) == 0)) {
1160                         /* This is the right entry. */
1161                         nvmem = __nvmem_device_get((void *)lookup->nvmem_name,
1162                                                    device_match_name);
1163                         if (IS_ERR(nvmem)) {
1164                                 /* Provider may not be registered yet. */
1165                                 cell = ERR_CAST(nvmem);
1166                                 break;
1167                         }
1168
1169                         cell = nvmem_find_cell_by_name(nvmem,
1170                                                        lookup->cell_name);
1171                         if (!cell) {
1172                                 __nvmem_device_put(nvmem);
1173                                 cell = ERR_PTR(-ENOENT);
1174                         }
1175                         break;
1176                 }
1177         }
1178
1179         mutex_unlock(&nvmem_lookup_mutex);
1180         return cell;
1181 }
1182
1183 #if IS_ENABLED(CONFIG_OF)
1184 static struct nvmem_cell *
1185 nvmem_find_cell_by_node(struct nvmem_device *nvmem, struct device_node *np)
1186 {
1187         struct nvmem_cell *iter, *cell = NULL;
1188
1189         mutex_lock(&nvmem_mutex);
1190         list_for_each_entry(iter, &nvmem->cells, node) {
1191                 if (np == iter->np) {
1192                         cell = iter;
1193                         break;
1194                 }
1195         }
1196         mutex_unlock(&nvmem_mutex);
1197
1198         return cell;
1199 }
1200
1201 /**
1202  * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
1203  *
1204  * @np: Device tree node that uses the nvmem cell.
1205  * @id: nvmem cell name from nvmem-cell-names property, or NULL
1206  *      for the cell at index 0 (the lone cell with no accompanying
1207  *      nvmem-cell-names property).
1208  *
1209  * Return: Will be an ERR_PTR() on error or a valid pointer
1210  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1211  * nvmem_cell_put().
1212  */
1213 struct nvmem_cell *of_nvmem_cell_get(struct device_node *np, const char *id)
1214 {
1215         struct device_node *cell_np, *nvmem_np;
1216         struct nvmem_device *nvmem;
1217         struct nvmem_cell *cell;
1218         int index = 0;
1219
1220         /* if cell name exists, find index to the name */
1221         if (id)
1222                 index = of_property_match_string(np, "nvmem-cell-names", id);
1223
1224         cell_np = of_parse_phandle(np, "nvmem-cells", index);
1225         if (!cell_np)
1226                 return ERR_PTR(-ENOENT);
1227
1228         nvmem_np = of_get_next_parent(cell_np);
1229         if (!nvmem_np)
1230                 return ERR_PTR(-EINVAL);
1231
1232         nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
1233         of_node_put(nvmem_np);
1234         if (IS_ERR(nvmem))
1235                 return ERR_CAST(nvmem);
1236
1237         cell = nvmem_find_cell_by_node(nvmem, cell_np);
1238         if (!cell) {
1239                 __nvmem_device_put(nvmem);
1240                 return ERR_PTR(-ENOENT);
1241         }
1242
1243         return cell;
1244 }
1245 EXPORT_SYMBOL_GPL(of_nvmem_cell_get);
1246 #endif
1247
1248 /**
1249  * nvmem_cell_get() - Get nvmem cell of device form a given cell name
1250  *
1251  * @dev: Device that requests the nvmem cell.
1252  * @id: nvmem cell name to get (this corresponds with the name from the
1253  *      nvmem-cell-names property for DT systems and with the con_id from
1254  *      the lookup entry for non-DT systems).
1255  *
1256  * Return: Will be an ERR_PTR() on error or a valid pointer
1257  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1258  * nvmem_cell_put().
1259  */
1260 struct nvmem_cell *nvmem_cell_get(struct device *dev, const char *id)
1261 {
1262         struct nvmem_cell *cell;
1263
1264         if (dev->of_node) { /* try dt first */
1265                 cell = of_nvmem_cell_get(dev->of_node, id);
1266                 if (!IS_ERR(cell) || PTR_ERR(cell) == -EPROBE_DEFER)
1267                         return cell;
1268         }
1269
1270         /* NULL cell id only allowed for device tree; invalid otherwise */
1271         if (!id)
1272                 return ERR_PTR(-EINVAL);
1273
1274         return nvmem_cell_get_from_lookup(dev, id);
1275 }
1276 EXPORT_SYMBOL_GPL(nvmem_cell_get);
1277
1278 static void devm_nvmem_cell_release(struct device *dev, void *res)
1279 {
1280         nvmem_cell_put(*(struct nvmem_cell **)res);
1281 }
1282
1283 /**
1284  * devm_nvmem_cell_get() - Get nvmem cell of device form a given id
1285  *
1286  * @dev: Device that requests the nvmem cell.
1287  * @id: nvmem cell name id to get.
1288  *
1289  * Return: Will be an ERR_PTR() on error or a valid pointer
1290  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1291  * automatically once the device is freed.
1292  */
1293 struct nvmem_cell *devm_nvmem_cell_get(struct device *dev, const char *id)
1294 {
1295         struct nvmem_cell **ptr, *cell;
1296
1297         ptr = devres_alloc(devm_nvmem_cell_release, sizeof(*ptr), GFP_KERNEL);
1298         if (!ptr)
1299                 return ERR_PTR(-ENOMEM);
1300
1301         cell = nvmem_cell_get(dev, id);
1302         if (!IS_ERR(cell)) {
1303                 *ptr = cell;
1304                 devres_add(dev, ptr);
1305         } else {
1306                 devres_free(ptr);
1307         }
1308
1309         return cell;
1310 }
1311 EXPORT_SYMBOL_GPL(devm_nvmem_cell_get);
1312
1313 static int devm_nvmem_cell_match(struct device *dev, void *res, void *data)
1314 {
1315         struct nvmem_cell **c = res;
1316
1317         if (WARN_ON(!c || !*c))
1318                 return 0;
1319
1320         return *c == data;
1321 }
1322
1323 /**
1324  * devm_nvmem_cell_put() - Release previously allocated nvmem cell
1325  * from devm_nvmem_cell_get.
1326  *
1327  * @dev: Device that requests the nvmem cell.
1328  * @cell: Previously allocated nvmem cell by devm_nvmem_cell_get().
1329  */
1330 void devm_nvmem_cell_put(struct device *dev, struct nvmem_cell *cell)
1331 {
1332         int ret;
1333
1334         ret = devres_release(dev, devm_nvmem_cell_release,
1335                                 devm_nvmem_cell_match, cell);
1336
1337         WARN_ON(ret);
1338 }
1339 EXPORT_SYMBOL(devm_nvmem_cell_put);
1340
1341 /**
1342  * nvmem_cell_put() - Release previously allocated nvmem cell.
1343  *
1344  * @cell: Previously allocated nvmem cell by nvmem_cell_get().
1345  */
1346 void nvmem_cell_put(struct nvmem_cell *cell)
1347 {
1348         struct nvmem_device *nvmem = cell->nvmem;
1349
1350         __nvmem_device_put(nvmem);
1351 }
1352 EXPORT_SYMBOL_GPL(nvmem_cell_put);
1353
1354 static void nvmem_shift_read_buffer_in_place(struct nvmem_cell *cell, void *buf)
1355 {
1356         u8 *p, *b;
1357         int i, extra, bit_offset = cell->bit_offset;
1358
1359         p = b = buf;
1360         if (bit_offset) {
1361                 /* First shift */
1362                 *b++ >>= bit_offset;
1363
1364                 /* setup rest of the bytes if any */
1365                 for (i = 1; i < cell->bytes; i++) {
1366                         /* Get bits from next byte and shift them towards msb */
1367                         *p |= *b << (BITS_PER_BYTE - bit_offset);
1368
1369                         p = b;
1370                         *b++ >>= bit_offset;
1371                 }
1372         } else {
1373                 /* point to the msb */
1374                 p += cell->bytes - 1;
1375         }
1376
1377         /* result fits in less bytes */
1378         extra = cell->bytes - DIV_ROUND_UP(cell->nbits, BITS_PER_BYTE);
1379         while (--extra >= 0)
1380                 *p-- = 0;
1381
1382         /* clear msb bits if any leftover in the last byte */
1383         *p &= GENMASK((cell->nbits%BITS_PER_BYTE) - 1, 0);
1384 }
1385
1386 static int __nvmem_cell_read(struct nvmem_device *nvmem,
1387                       struct nvmem_cell *cell,
1388                       void *buf, size_t *len)
1389 {
1390         int rc;
1391
1392         rc = nvmem_reg_read(nvmem, cell->offset, buf, cell->bytes);
1393
1394         if (rc)
1395                 return rc;
1396
1397         /* shift bits in-place */
1398         if (cell->bit_offset || cell->nbits)
1399                 nvmem_shift_read_buffer_in_place(cell, buf);
1400
1401         if (len)
1402                 *len = cell->bytes;
1403
1404         return 0;
1405 }
1406
1407 /**
1408  * nvmem_cell_read() - Read a given nvmem cell
1409  *
1410  * @cell: nvmem cell to be read.
1411  * @len: pointer to length of cell which will be populated on successful read;
1412  *       can be NULL.
1413  *
1414  * Return: ERR_PTR() on error or a valid pointer to a buffer on success. The
1415  * buffer should be freed by the consumer with a kfree().
1416  */
1417 void *nvmem_cell_read(struct nvmem_cell *cell, size_t *len)
1418 {
1419         struct nvmem_device *nvmem = cell->nvmem;
1420         u8 *buf;
1421         int rc;
1422
1423         if (!nvmem)
1424                 return ERR_PTR(-EINVAL);
1425
1426         buf = kzalloc(cell->bytes, GFP_KERNEL);
1427         if (!buf)
1428                 return ERR_PTR(-ENOMEM);
1429
1430         rc = __nvmem_cell_read(nvmem, cell, buf, len);
1431         if (rc) {
1432                 kfree(buf);
1433                 return ERR_PTR(rc);
1434         }
1435
1436         return buf;
1437 }
1438 EXPORT_SYMBOL_GPL(nvmem_cell_read);
1439
1440 static void *nvmem_cell_prepare_write_buffer(struct nvmem_cell *cell,
1441                                              u8 *_buf, int len)
1442 {
1443         struct nvmem_device *nvmem = cell->nvmem;
1444         int i, rc, nbits, bit_offset = cell->bit_offset;
1445         u8 v, *p, *buf, *b, pbyte, pbits;
1446
1447         nbits = cell->nbits;
1448         buf = kzalloc(cell->bytes, GFP_KERNEL);
1449         if (!buf)
1450                 return ERR_PTR(-ENOMEM);
1451
1452         memcpy(buf, _buf, len);
1453         p = b = buf;
1454
1455         if (bit_offset) {
1456                 pbyte = *b;
1457                 *b <<= bit_offset;
1458
1459                 /* setup the first byte with lsb bits from nvmem */
1460                 rc = nvmem_reg_read(nvmem, cell->offset, &v, 1);
1461                 if (rc)
1462                         goto err;
1463                 *b++ |= GENMASK(bit_offset - 1, 0) & v;
1464
1465                 /* setup rest of the byte if any */
1466                 for (i = 1; i < cell->bytes; i++) {
1467                         /* Get last byte bits and shift them towards lsb */
1468                         pbits = pbyte >> (BITS_PER_BYTE - 1 - bit_offset);
1469                         pbyte = *b;
1470                         p = b;
1471                         *b <<= bit_offset;
1472                         *b++ |= pbits;
1473                 }
1474         }
1475
1476         /* if it's not end on byte boundary */
1477         if ((nbits + bit_offset) % BITS_PER_BYTE) {
1478                 /* setup the last byte with msb bits from nvmem */
1479                 rc = nvmem_reg_read(nvmem,
1480                                     cell->offset + cell->bytes - 1, &v, 1);
1481                 if (rc)
1482                         goto err;
1483                 *p |= GENMASK(7, (nbits + bit_offset) % BITS_PER_BYTE) & v;
1484
1485         }
1486
1487         return buf;
1488 err:
1489         kfree(buf);
1490         return ERR_PTR(rc);
1491 }
1492
1493 /**
1494  * nvmem_cell_write() - Write to a given nvmem cell
1495  *
1496  * @cell: nvmem cell to be written.
1497  * @buf: Buffer to be written.
1498  * @len: length of buffer to be written to nvmem cell.
1499  *
1500  * Return: length of bytes written or negative on failure.
1501  */
1502 int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len)
1503 {
1504         struct nvmem_device *nvmem = cell->nvmem;
1505         int rc;
1506
1507         if (!nvmem || nvmem->read_only ||
1508             (cell->bit_offset == 0 && len != cell->bytes))
1509                 return -EINVAL;
1510
1511         if (cell->bit_offset || cell->nbits) {
1512                 buf = nvmem_cell_prepare_write_buffer(cell, buf, len);
1513                 if (IS_ERR(buf))
1514                         return PTR_ERR(buf);
1515         }
1516
1517         rc = nvmem_reg_write(nvmem, cell->offset, buf, cell->bytes);
1518
1519         /* free the tmp buffer */
1520         if (cell->bit_offset || cell->nbits)
1521                 kfree(buf);
1522
1523         if (rc)
1524                 return rc;
1525
1526         return len;
1527 }
1528 EXPORT_SYMBOL_GPL(nvmem_cell_write);
1529
1530 static int nvmem_cell_read_common(struct device *dev, const char *cell_id,
1531                                   void *val, size_t count)
1532 {
1533         struct nvmem_cell *cell;
1534         void *buf;
1535         size_t len;
1536
1537         cell = nvmem_cell_get(dev, cell_id);
1538         if (IS_ERR(cell))
1539                 return PTR_ERR(cell);
1540
1541         buf = nvmem_cell_read(cell, &len);
1542         if (IS_ERR(buf)) {
1543                 nvmem_cell_put(cell);
1544                 return PTR_ERR(buf);
1545         }
1546         if (len != count) {
1547                 kfree(buf);
1548                 nvmem_cell_put(cell);
1549                 return -EINVAL;
1550         }
1551         memcpy(val, buf, count);
1552         kfree(buf);
1553         nvmem_cell_put(cell);
1554
1555         return 0;
1556 }
1557
1558 /**
1559  * nvmem_cell_read_u8() - Read a cell value as a u8
1560  *
1561  * @dev: Device that requests the nvmem cell.
1562  * @cell_id: Name of nvmem cell to read.
1563  * @val: pointer to output value.
1564  *
1565  * Return: 0 on success or negative errno.
1566  */
1567 int nvmem_cell_read_u8(struct device *dev, const char *cell_id, u8 *val)
1568 {
1569         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1570 }
1571 EXPORT_SYMBOL_GPL(nvmem_cell_read_u8);
1572
1573 /**
1574  * nvmem_cell_read_u16() - Read a cell value as a u16
1575  *
1576  * @dev: Device that requests the nvmem cell.
1577  * @cell_id: Name of nvmem cell to read.
1578  * @val: pointer to output value.
1579  *
1580  * Return: 0 on success or negative errno.
1581  */
1582 int nvmem_cell_read_u16(struct device *dev, const char *cell_id, u16 *val)
1583 {
1584         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1585 }
1586 EXPORT_SYMBOL_GPL(nvmem_cell_read_u16);
1587
1588 /**
1589  * nvmem_cell_read_u32() - Read a cell value as a u32
1590  *
1591  * @dev: Device that requests the nvmem cell.
1592  * @cell_id: Name of nvmem cell to read.
1593  * @val: pointer to output value.
1594  *
1595  * Return: 0 on success or negative errno.
1596  */
1597 int nvmem_cell_read_u32(struct device *dev, const char *cell_id, u32 *val)
1598 {
1599         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1600 }
1601 EXPORT_SYMBOL_GPL(nvmem_cell_read_u32);
1602
1603 /**
1604  * nvmem_cell_read_u64() - Read a cell value as a u64
1605  *
1606  * @dev: Device that requests the nvmem cell.
1607  * @cell_id: Name of nvmem cell to read.
1608  * @val: pointer to output value.
1609  *
1610  * Return: 0 on success or negative errno.
1611  */
1612 int nvmem_cell_read_u64(struct device *dev, const char *cell_id, u64 *val)
1613 {
1614         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1615 }
1616 EXPORT_SYMBOL_GPL(nvmem_cell_read_u64);
1617
1618 static const void *nvmem_cell_read_variable_common(struct device *dev,
1619                                                    const char *cell_id,
1620                                                    size_t max_len, size_t *len)
1621 {
1622         struct nvmem_cell *cell;
1623         int nbits;
1624         void *buf;
1625
1626         cell = nvmem_cell_get(dev, cell_id);
1627         if (IS_ERR(cell))
1628                 return cell;
1629
1630         nbits = cell->nbits;
1631         buf = nvmem_cell_read(cell, len);
1632         nvmem_cell_put(cell);
1633         if (IS_ERR(buf))
1634                 return buf;
1635
1636         /*
1637          * If nbits is set then nvmem_cell_read() can significantly exaggerate
1638          * the length of the real data. Throw away the extra junk.
1639          */
1640         if (nbits)
1641                 *len = DIV_ROUND_UP(nbits, 8);
1642
1643         if (*len > max_len) {
1644                 kfree(buf);
1645                 return ERR_PTR(-ERANGE);
1646         }
1647
1648         return buf;
1649 }
1650
1651 /**
1652  * nvmem_cell_read_variable_le_u32() - Read up to 32-bits of data as a little endian number.
1653  *
1654  * @dev: Device that requests the nvmem cell.
1655  * @cell_id: Name of nvmem cell to read.
1656  * @val: pointer to output value.
1657  *
1658  * Return: 0 on success or negative errno.
1659  */
1660 int nvmem_cell_read_variable_le_u32(struct device *dev, const char *cell_id,
1661                                     u32 *val)
1662 {
1663         size_t len;
1664         const u8 *buf;
1665         int i;
1666
1667         buf = nvmem_cell_read_variable_common(dev, cell_id, sizeof(*val), &len);
1668         if (IS_ERR(buf))
1669                 return PTR_ERR(buf);
1670
1671         /* Copy w/ implicit endian conversion */
1672         *val = 0;
1673         for (i = 0; i < len; i++)
1674                 *val |= buf[i] << (8 * i);
1675
1676         kfree(buf);
1677
1678         return 0;
1679 }
1680 EXPORT_SYMBOL_GPL(nvmem_cell_read_variable_le_u32);
1681
1682 /**
1683  * nvmem_cell_read_variable_le_u64() - Read up to 64-bits of data as a little endian number.
1684  *
1685  * @dev: Device that requests the nvmem cell.
1686  * @cell_id: Name of nvmem cell to read.
1687  * @val: pointer to output value.
1688  *
1689  * Return: 0 on success or negative errno.
1690  */
1691 int nvmem_cell_read_variable_le_u64(struct device *dev, const char *cell_id,
1692                                     u64 *val)
1693 {
1694         size_t len;
1695         const u8 *buf;
1696         int i;
1697
1698         buf = nvmem_cell_read_variable_common(dev, cell_id, sizeof(*val), &len);
1699         if (IS_ERR(buf))
1700                 return PTR_ERR(buf);
1701
1702         /* Copy w/ implicit endian conversion */
1703         *val = 0;
1704         for (i = 0; i < len; i++)
1705                 *val |= (uint64_t)buf[i] << (8 * i);
1706
1707         kfree(buf);
1708
1709         return 0;
1710 }
1711 EXPORT_SYMBOL_GPL(nvmem_cell_read_variable_le_u64);
1712
1713 /**
1714  * nvmem_device_cell_read() - Read a given nvmem device and cell
1715  *
1716  * @nvmem: nvmem device to read from.
1717  * @info: nvmem cell info to be read.
1718  * @buf: buffer pointer which will be populated on successful read.
1719  *
1720  * Return: length of successful bytes read on success and negative
1721  * error code on error.
1722  */
1723 ssize_t nvmem_device_cell_read(struct nvmem_device *nvmem,
1724                            struct nvmem_cell_info *info, void *buf)
1725 {
1726         struct nvmem_cell cell;
1727         int rc;
1728         ssize_t len;
1729
1730         if (!nvmem)
1731                 return -EINVAL;
1732
1733         rc = nvmem_cell_info_to_nvmem_cell_nodup(nvmem, info, &cell);
1734         if (rc)
1735                 return rc;
1736
1737         rc = __nvmem_cell_read(nvmem, &cell, buf, &len);
1738         if (rc)
1739                 return rc;
1740
1741         return len;
1742 }
1743 EXPORT_SYMBOL_GPL(nvmem_device_cell_read);
1744
1745 /**
1746  * nvmem_device_cell_write() - Write cell to a given nvmem device
1747  *
1748  * @nvmem: nvmem device to be written to.
1749  * @info: nvmem cell info to be written.
1750  * @buf: buffer to be written to cell.
1751  *
1752  * Return: length of bytes written or negative error code on failure.
1753  */
1754 int nvmem_device_cell_write(struct nvmem_device *nvmem,
1755                             struct nvmem_cell_info *info, void *buf)
1756 {
1757         struct nvmem_cell cell;
1758         int rc;
1759
1760         if (!nvmem)
1761                 return -EINVAL;
1762
1763         rc = nvmem_cell_info_to_nvmem_cell_nodup(nvmem, info, &cell);
1764         if (rc)
1765                 return rc;
1766
1767         return nvmem_cell_write(&cell, buf, cell.bytes);
1768 }
1769 EXPORT_SYMBOL_GPL(nvmem_device_cell_write);
1770
1771 /**
1772  * nvmem_device_read() - Read from a given nvmem device
1773  *
1774  * @nvmem: nvmem device to read from.
1775  * @offset: offset in nvmem device.
1776  * @bytes: number of bytes to read.
1777  * @buf: buffer pointer which will be populated on successful read.
1778  *
1779  * Return: length of successful bytes read on success and negative
1780  * error code on error.
1781  */
1782 int nvmem_device_read(struct nvmem_device *nvmem,
1783                       unsigned int offset,
1784                       size_t bytes, void *buf)
1785 {
1786         int rc;
1787
1788         if (!nvmem)
1789                 return -EINVAL;
1790
1791         rc = nvmem_reg_read(nvmem, offset, buf, bytes);
1792
1793         if (rc)
1794                 return rc;
1795
1796         return bytes;
1797 }
1798 EXPORT_SYMBOL_GPL(nvmem_device_read);
1799
1800 /**
1801  * nvmem_device_write() - Write cell to a given nvmem device
1802  *
1803  * @nvmem: nvmem device to be written to.
1804  * @offset: offset in nvmem device.
1805  * @bytes: number of bytes to write.
1806  * @buf: buffer to be written.
1807  *
1808  * Return: length of bytes written or negative error code on failure.
1809  */
1810 int nvmem_device_write(struct nvmem_device *nvmem,
1811                        unsigned int offset,
1812                        size_t bytes, void *buf)
1813 {
1814         int rc;
1815
1816         if (!nvmem)
1817                 return -EINVAL;
1818
1819         rc = nvmem_reg_write(nvmem, offset, buf, bytes);
1820
1821         if (rc)
1822                 return rc;
1823
1824
1825         return bytes;
1826 }
1827 EXPORT_SYMBOL_GPL(nvmem_device_write);
1828
1829 /**
1830  * nvmem_add_cell_table() - register a table of cell info entries
1831  *
1832  * @table: table of cell info entries
1833  */
1834 void nvmem_add_cell_table(struct nvmem_cell_table *table)
1835 {
1836         mutex_lock(&nvmem_cell_mutex);
1837         list_add_tail(&table->node, &nvmem_cell_tables);
1838         mutex_unlock(&nvmem_cell_mutex);
1839 }
1840 EXPORT_SYMBOL_GPL(nvmem_add_cell_table);
1841
1842 /**
1843  * nvmem_del_cell_table() - remove a previously registered cell info table
1844  *
1845  * @table: table of cell info entries
1846  */
1847 void nvmem_del_cell_table(struct nvmem_cell_table *table)
1848 {
1849         mutex_lock(&nvmem_cell_mutex);
1850         list_del(&table->node);
1851         mutex_unlock(&nvmem_cell_mutex);
1852 }
1853 EXPORT_SYMBOL_GPL(nvmem_del_cell_table);
1854
1855 /**
1856  * nvmem_add_cell_lookups() - register a list of cell lookup entries
1857  *
1858  * @entries: array of cell lookup entries
1859  * @nentries: number of cell lookup entries in the array
1860  */
1861 void nvmem_add_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
1862 {
1863         int i;
1864
1865         mutex_lock(&nvmem_lookup_mutex);
1866         for (i = 0; i < nentries; i++)
1867                 list_add_tail(&entries[i].node, &nvmem_lookup_list);
1868         mutex_unlock(&nvmem_lookup_mutex);
1869 }
1870 EXPORT_SYMBOL_GPL(nvmem_add_cell_lookups);
1871
1872 /**
1873  * nvmem_del_cell_lookups() - remove a list of previously added cell lookup
1874  *                            entries
1875  *
1876  * @entries: array of cell lookup entries
1877  * @nentries: number of cell lookup entries in the array
1878  */
1879 void nvmem_del_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
1880 {
1881         int i;
1882
1883         mutex_lock(&nvmem_lookup_mutex);
1884         for (i = 0; i < nentries; i++)
1885                 list_del(&entries[i].node);
1886         mutex_unlock(&nvmem_lookup_mutex);
1887 }
1888 EXPORT_SYMBOL_GPL(nvmem_del_cell_lookups);
1889
1890 /**
1891  * nvmem_dev_name() - Get the name of a given nvmem device.
1892  *
1893  * @nvmem: nvmem device.
1894  *
1895  * Return: name of the nvmem device.
1896  */
1897 const char *nvmem_dev_name(struct nvmem_device *nvmem)
1898 {
1899         return dev_name(&nvmem->dev);
1900 }
1901 EXPORT_SYMBOL_GPL(nvmem_dev_name);
1902
1903 static int __init nvmem_init(void)
1904 {
1905         return bus_register(&nvmem_bus_type);
1906 }
1907
1908 static void __exit nvmem_exit(void)
1909 {
1910         bus_unregister(&nvmem_bus_type);
1911 }
1912
1913 subsys_initcall(nvmem_init);
1914 module_exit(nvmem_exit);
1915
1916 MODULE_AUTHOR("Srinivas Kandagatla <srinivas.kandagatla@linaro.org");
1917 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com");
1918 MODULE_DESCRIPTION("nvmem Driver Core");
1919 MODULE_LICENSE("GPL v2");