drivers/nvmem/core.c

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