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