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->no_of_node)
 793                 nvmem->dev.of_node = config->dev->of_node;
 794
 795         switch (config->id) {
 796         case NVMEM_DEVID_NONE:
 797                 dev_set_name(&nvmem->dev, "%s", config->name);
 798                 break;
 799         case NVMEM_DEVID_AUTO:
 800                 dev_set_name(&nvmem->dev, "%s%d", config->name, nvmem->id);
 801                 break;
 802         default:
 803                 dev_set_name(&nvmem->dev, "%s%d",
 804                              config->name ? : "nvmem",
 805                              config->name ? config->id : nvmem->id);
 806                 break;
 807         }
 808
 809         nvmem->read_only = device_property_present(config->dev, "read-only") ||
 810                            config->read_only || !nvmem->reg_write;
 811
 812 #ifdef CONFIG_NVMEM_SYSFS
 813         nvmem->dev.groups = nvmem_dev_groups;
 814 #endif
 815
 816         if (nvmem->nkeepout) {
 817                 rval = nvmem_validate_keepouts(nvmem);
 818                 if (rval)
 819                         goto err_put_device;
 820         }
 821
 822         dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
 823
 824         rval = device_register(&nvmem->dev);
 825         if (rval)
 826                 goto err_put_device;
 827
 828         if (config->compat) {
 829                 rval = nvmem_sysfs_setup_compat(nvmem, config);
 830                 if (rval)
 831                         goto err_device_del;
 832         }
 833
 834         if (config->cells) {
 835                 rval = nvmem_add_cells(nvmem, config->cells, config->ncells);
 836                 if (rval)
 837                         goto err_teardown_compat;
 838         }
 839
 840         rval = nvmem_add_cells_from_table(nvmem);
 841         if (rval)
 842                 goto err_remove_cells;
 843
 844         rval = nvmem_add_cells_from_of(nvmem);
 845         if (rval)
 846                 goto err_remove_cells;
 847
 848         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem);
 849
 850         return nvmem;
 851
 852 err_remove_cells:
 853         nvmem_device_remove_all_cells(nvmem);
 854 err_teardown_compat:
 855         if (config->compat)
 856                 nvmem_sysfs_remove_compat(nvmem, config);
 857 err_device_del:
 858         device_del(&nvmem->dev);
 859 err_put_device:
 860         put_device(&nvmem->dev);
 861
 862         return ERR_PTR(rval);
 863 }
 864 EXPORT_SYMBOL_GPL(nvmem_register);
 865
 866 static void nvmem_device_release(struct kref *kref)
 867 {
 868         struct nvmem_device *nvmem;
 869
 870         nvmem = container_of(kref, struct nvmem_device, refcnt);
 871
 872         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_REMOVE, nvmem);
 873
 874         if (nvmem->flags & FLAG_COMPAT)
 875                 device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
 876
 877         nvmem_device_remove_all_cells(nvmem);
 878         device_unregister(&nvmem->dev);
 879 }
 880
 881 /**
 882  * nvmem_unregister() - Unregister previously registered nvmem device
 883  *
 884  * @nvmem: Pointer to previously registered nvmem device.
 885  */
 886 void nvmem_unregister(struct nvmem_device *nvmem)
 887 {
 888         kref_put(&nvmem->refcnt, nvmem_device_release);
 889 }
 890 EXPORT_SYMBOL_GPL(nvmem_unregister);
 891
 892 static void devm_nvmem_release(struct device *dev, void *res)
 893 {
 894         nvmem_unregister(*(struct nvmem_device **)res);
 895 }
 896
 897 /**
 898  * devm_nvmem_register() - Register a managed nvmem device for given
 899  * nvmem_config.
 900  * Also creates a binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
 901  *
 902  * @dev: Device that uses the nvmem device.
 903  * @config: nvmem device configuration with which nvmem device is created.
 904  *
 905  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
 906  * on success.
 907  */
 908 struct nvmem_device *devm_nvmem_register(struct device *dev,
 909                                          const struct nvmem_config *config)
 910 {
 911         struct nvmem_device **ptr, *nvmem;
 912
 913         ptr = devres_alloc(devm_nvmem_release, sizeof(*ptr), GFP_KERNEL);
 914         if (!ptr)
 915                 return ERR_PTR(-ENOMEM);
 916
 917         nvmem = nvmem_register(config);
 918
 919         if (!IS_ERR(nvmem)) {
 920                 *ptr = nvmem;
 921                 devres_add(dev, ptr);
 922         } else {
 923                 devres_free(ptr);
 924         }
 925
 926         return nvmem;
 927 }
 928 EXPORT_SYMBOL_GPL(devm_nvmem_register);
 929
 930 static int devm_nvmem_match(struct device *dev, void *res, void *data)
 931 {
 932         struct nvmem_device **r = res;
 933
 934         return *r == data;
 935 }
 936
 937 /**
 938  * devm_nvmem_unregister() - Unregister previously registered managed nvmem
 939  * device.
 940  *
 941  * @dev: Device that uses the nvmem device.
 942  * @nvmem: Pointer to previously registered nvmem device.
 943  *
 944  * Return: Will be negative on error or zero on success.
 945  */
 946 int devm_nvmem_unregister(struct device *dev, struct nvmem_device *nvmem)
 947 {
 948         return devres_release(dev, devm_nvmem_release, devm_nvmem_match, nvmem);
 949 }
 950 EXPORT_SYMBOL(devm_nvmem_unregister);
 951
 952 static struct nvmem_device *__nvmem_device_get(void *data,
 953                         int (*match)(struct device *dev, const void *data))
 954 {
 955         struct nvmem_device *nvmem = NULL;
 956         struct device *dev;
 957
 958         mutex_lock(&nvmem_mutex);
 959         dev = bus_find_device(&nvmem_bus_type, NULL, data, match);
 960         if (dev)
 961                 nvmem = to_nvmem_device(dev);
 962         mutex_unlock(&nvmem_mutex);
 963         if (!nvmem)
 964                 return ERR_PTR(-EPROBE_DEFER);
 965
 966         if (!try_module_get(nvmem->owner)) {
 967                 dev_err(&nvmem->dev,
 968                         "could not increase module refcount for cell %s\n",
 969                         nvmem_dev_name(nvmem));
 970
 971                 put_device(&nvmem->dev);
 972                 return ERR_PTR(-EINVAL);
 973         }
 974
 975         kref_get(&nvmem->refcnt);
 976
 977         return nvmem;
 978 }
 979
 980 static void __nvmem_device_put(struct nvmem_device *nvmem)
 981 {
 982         put_device(&nvmem->dev);
 983         module_put(nvmem->owner);
 984         kref_put(&nvmem->refcnt, nvmem_device_release);
 985 }
 986
 987 #if IS_ENABLED(CONFIG_OF)
 988 /**
 989  * of_nvmem_device_get() - Get nvmem device from a given id
 990  *
 991  * @np: Device tree node that uses the nvmem device.
 992  * @id: nvmem name from nvmem-names property.
 993  *
 994  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
 995  * on success.
 996  */
 997 struct nvmem_device *of_nvmem_device_get(struct device_node *np, const char *id)
 998 {
 999
1000         struct device_node *nvmem_np;
1001         struct nvmem_device *nvmem;
1002         int index = 0;
1003
1004         if (id)
1005                 index = of_property_match_string(np, "nvmem-names", id);
1006
1007         nvmem_np = of_parse_phandle(np, "nvmem", index);
1008         if (!nvmem_np)
1009                 return ERR_PTR(-ENOENT);
1010
1011         nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
1012         of_node_put(nvmem_np);
1013         return nvmem;
1014 }
1015 EXPORT_SYMBOL_GPL(of_nvmem_device_get);
1016 #endif
1017
1018 /**
1019  * nvmem_device_get() - Get nvmem device from a given id
1020  *
1021  * @dev: Device that uses the nvmem device.
1022  * @dev_name: name of the requested nvmem device.
1023  *
1024  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1025  * on success.
1026  */
1027 struct nvmem_device *nvmem_device_get(struct device *dev, const char *dev_name)
1028 {
1029         if (dev->of_node) { /* try dt first */
1030                 struct nvmem_device *nvmem;
1031
1032                 nvmem = of_nvmem_device_get(dev->of_node, dev_name);
1033
1034                 if (!IS_ERR(nvmem) || PTR_ERR(nvmem) == -EPROBE_DEFER)
1035                         return nvmem;
1036
1037         }
1038
1039         return __nvmem_device_get((void *)dev_name, device_match_name);
1040 }
1041 EXPORT_SYMBOL_GPL(nvmem_device_get);
1042
1043 /**
1044  * nvmem_device_find() - Find nvmem device with matching function
1045  *
1046  * @data: Data to pass to match function
1047  * @match: Callback function to check device
1048  *
1049  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1050  * on success.
1051  */
1052 struct nvmem_device *nvmem_device_find(void *data,
1053                         int (*match)(struct device *dev, const void *data))
1054 {
1055         return __nvmem_device_get(data, match);
1056 }
1057 EXPORT_SYMBOL_GPL(nvmem_device_find);
1058
1059 static int devm_nvmem_device_match(struct device *dev, void *res, void *data)
1060 {
1061         struct nvmem_device **nvmem = res;
1062
1063         if (WARN_ON(!nvmem || !*nvmem))
1064                 return 0;
1065
1066         return *nvmem == data;
1067 }
1068
1069 static void devm_nvmem_device_release(struct device *dev, void *res)
1070 {
1071         nvmem_device_put(*(struct nvmem_device **)res);
1072 }
1073
1074 /**
1075  * devm_nvmem_device_put() - put alredy got nvmem device
1076  *
1077  * @dev: Device that uses the nvmem device.
1078  * @nvmem: pointer to nvmem device allocated by devm_nvmem_cell_get(),
1079  * that needs to be released.
1080  */
1081 void devm_nvmem_device_put(struct device *dev, struct nvmem_device *nvmem)
1082 {
1083         int ret;
1084
1085         ret = devres_release(dev, devm_nvmem_device_release,
1086                              devm_nvmem_device_match, nvmem);
1087
1088         WARN_ON(ret);
1089 }
1090 EXPORT_SYMBOL_GPL(devm_nvmem_device_put);
1091
1092 /**
1093  * nvmem_device_put() - put alredy got nvmem device
1094  *
1095  * @nvmem: pointer to nvmem device that needs to be released.
1096  */
1097 void nvmem_device_put(struct nvmem_device *nvmem)
1098 {
1099         __nvmem_device_put(nvmem);
1100 }
1101 EXPORT_SYMBOL_GPL(nvmem_device_put);
1102
1103 /**
1104  * devm_nvmem_device_get() - Get nvmem cell of device form a given id
1105  *
1106  * @dev: Device that requests the nvmem device.
1107  * @id: name id for the requested nvmem device.
1108  *
1109  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_cell
1110  * on success.  The nvmem_cell will be freed by the automatically once the
1111  * device is freed.
1112  */
1113 struct nvmem_device *devm_nvmem_device_get(struct device *dev, const char *id)
1114 {
1115         struct nvmem_device **ptr, *nvmem;
1116
1117         ptr = devres_alloc(devm_nvmem_device_release, sizeof(*ptr), GFP_KERNEL);
1118         if (!ptr)
1119                 return ERR_PTR(-ENOMEM);
1120
1121         nvmem = nvmem_device_get(dev, id);
1122         if (!IS_ERR(nvmem)) {
1123                 *ptr = nvmem;
1124                 devres_add(dev, ptr);
1125         } else {
1126                 devres_free(ptr);
1127         }
1128
1129         return nvmem;
1130 }
1131 EXPORT_SYMBOL_GPL(devm_nvmem_device_get);
1132
1133 static struct nvmem_cell *
1134 nvmem_cell_get_from_lookup(struct device *dev, const char *con_id)
1135 {
1136         struct nvmem_cell *cell = ERR_PTR(-ENOENT);
1137         struct nvmem_cell_lookup *lookup;
1138         struct nvmem_device *nvmem;
1139         const char *dev_id;
1140
1141         if (!dev)
1142                 return ERR_PTR(-EINVAL);
1143
1144         dev_id = dev_name(dev);
1145
1146         mutex_lock(&nvmem_lookup_mutex);
1147
1148         list_for_each_entry(lookup, &nvmem_lookup_list, node) {
1149                 if ((strcmp(lookup->dev_id, dev_id) == 0) &&
1150                     (strcmp(lookup->con_id, con_id) == 0)) {
1151                         /* This is the right entry. */
1152                         nvmem = __nvmem_device_get((void *)lookup->nvmem_name,
1153                                                    device_match_name);
1154                         if (IS_ERR(nvmem)) {
1155                                 /* Provider may not be registered yet. */
1156                                 cell = ERR_CAST(nvmem);
1157                                 break;
1158                         }
1159
1160                         cell = nvmem_find_cell_by_name(nvmem,
1161                                                        lookup->cell_name);
1162                         if (!cell) {
1163                                 __nvmem_device_put(nvmem);
1164                                 cell = ERR_PTR(-ENOENT);
1165                         }
1166                         break;
1167                 }
1168         }
1169
1170         mutex_unlock(&nvmem_lookup_mutex);
1171         return cell;
1172 }
1173
1174 #if IS_ENABLED(CONFIG_OF)
1175 static struct nvmem_cell *
1176 nvmem_find_cell_by_node(struct nvmem_device *nvmem, struct device_node *np)
1177 {
1178         struct nvmem_cell *iter, *cell = NULL;
1179
1180         mutex_lock(&nvmem_mutex);
1181         list_for_each_entry(iter, &nvmem->cells, node) {
1182                 if (np == iter->np) {
1183                         cell = iter;
1184                         break;
1185                 }
1186         }
1187         mutex_unlock(&nvmem_mutex);
1188
1189         return cell;
1190 }
1191
1192 /**
1193  * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
1194  *
1195  * @np: Device tree node that uses the nvmem cell.
1196  * @id: nvmem cell name from nvmem-cell-names property, or NULL
1197  *      for the cell at index 0 (the lone cell with no accompanying
1198  *      nvmem-cell-names property).
1199  *
1200  * Return: Will be an ERR_PTR() on error or a valid pointer
1201  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1202  * nvmem_cell_put().
1203  */
1204 struct nvmem_cell *of_nvmem_cell_get(struct device_node *np, const char *id)
1205 {
1206         struct device_node *cell_np, *nvmem_np;
1207         struct nvmem_device *nvmem;
1208         struct nvmem_cell *cell;
1209         int index = 0;
1210
1211         /* if cell name exists, find index to the name */
1212         if (id)
1213                 index = of_property_match_string(np, "nvmem-cell-names", id);
1214
1215         cell_np = of_parse_phandle(np, "nvmem-cells", index);
1216         if (!cell_np)
1217                 return ERR_PTR(-ENOENT);
1218
1219         nvmem_np = of_get_next_parent(cell_np);
1220         if (!nvmem_np)
1221                 return ERR_PTR(-EINVAL);
1222
1223         nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
1224         of_node_put(nvmem_np);
1225         if (IS_ERR(nvmem))
1226                 return ERR_CAST(nvmem);
1227
1228         cell = nvmem_find_cell_by_node(nvmem, cell_np);
1229         if (!cell) {
1230                 __nvmem_device_put(nvmem);
1231                 return ERR_PTR(-ENOENT);
1232         }
1233
1234         return cell;
1235 }
1236 EXPORT_SYMBOL_GPL(of_nvmem_cell_get);
1237 #endif
1238
1239 /**
1240  * nvmem_cell_get() - Get nvmem cell of device form a given cell name
1241  *
1242  * @dev: Device that requests the nvmem cell.
1243  * @id: nvmem cell name to get (this corresponds with the name from the
1244  *      nvmem-cell-names property for DT systems and with the con_id from
1245  *      the lookup entry for non-DT systems).
1246  *
1247  * Return: Will be an ERR_PTR() on error or a valid pointer
1248  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1249  * nvmem_cell_put().
1250  */
1251 struct nvmem_cell *nvmem_cell_get(struct device *dev, const char *id)
1252 {
1253         struct nvmem_cell *cell;
1254
1255         if (dev->of_node) { /* try dt first */
1256                 cell = of_nvmem_cell_get(dev->of_node, id);
1257                 if (!IS_ERR(cell) || PTR_ERR(cell) == -EPROBE_DEFER)
1258                         return cell;
1259         }
1260
1261         /* NULL cell id only allowed for device tree; invalid otherwise */
1262         if (!id)
1263                 return ERR_PTR(-EINVAL);
1264
1265         return nvmem_cell_get_from_lookup(dev, id);
1266 }
1267 EXPORT_SYMBOL_GPL(nvmem_cell_get);
1268
1269 static void devm_nvmem_cell_release(struct device *dev, void *res)
1270 {
1271         nvmem_cell_put(*(struct nvmem_cell **)res);
1272 }
1273
1274 /**
1275  * devm_nvmem_cell_get() - Get nvmem cell of device form a given id
1276  *
1277  * @dev: Device that requests the nvmem cell.
1278  * @id: nvmem cell name id to get.
1279  *
1280  * Return: Will be an ERR_PTR() on error or a valid pointer
1281  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1282  * automatically once the device is freed.
1283  */
1284 struct nvmem_cell *devm_nvmem_cell_get(struct device *dev, const char *id)
1285 {
1286         struct nvmem_cell **ptr, *cell;
1287
1288         ptr = devres_alloc(devm_nvmem_cell_release, sizeof(*ptr), GFP_KERNEL);
1289         if (!ptr)
1290                 return ERR_PTR(-ENOMEM);
1291
1292         cell = nvmem_cell_get(dev, id);
1293         if (!IS_ERR(cell)) {
1294                 *ptr = cell;
1295                 devres_add(dev, ptr);
1296         } else {
1297                 devres_free(ptr);
1298         }
1299
1300         return cell;
1301 }
1302 EXPORT_SYMBOL_GPL(devm_nvmem_cell_get);
1303
1304 static int devm_nvmem_cell_match(struct device *dev, void *res, void *data)
1305 {
1306         struct nvmem_cell **c = res;
1307
1308         if (WARN_ON(!c || !*c))
1309                 return 0;
1310
1311         return *c == data;
1312 }
1313
1314 /**
1315  * devm_nvmem_cell_put() - Release previously allocated nvmem cell
1316  * from devm_nvmem_cell_get.
1317  *
1318  * @dev: Device that requests the nvmem cell.
1319  * @cell: Previously allocated nvmem cell by devm_nvmem_cell_get().
1320  */
1321 void devm_nvmem_cell_put(struct device *dev, struct nvmem_cell *cell)
1322 {
1323         int ret;
1324
1325         ret = devres_release(dev, devm_nvmem_cell_release,
1326                                 devm_nvmem_cell_match, cell);
1327
1328         WARN_ON(ret);
1329 }
1330 EXPORT_SYMBOL(devm_nvmem_cell_put);
1331
1332 /**
1333  * nvmem_cell_put() - Release previously allocated nvmem cell.
1334  *
1335  * @cell: Previously allocated nvmem cell by nvmem_cell_get().
1336  */
1337 void nvmem_cell_put(struct nvmem_cell *cell)
1338 {
1339         struct nvmem_device *nvmem = cell->nvmem;
1340
1341         __nvmem_device_put(nvmem);
1342 }
1343 EXPORT_SYMBOL_GPL(nvmem_cell_put);
1344
1345 static void nvmem_shift_read_buffer_in_place(struct nvmem_cell *cell, void *buf)
1346 {
1347         u8 *p, *b;
1348         int i, extra, bit_offset = cell->bit_offset;
1349
1350         p = b = buf;
1351         if (bit_offset) {
1352                 /* First shift */
1353                 *b++ >>= bit_offset;
1354
1355                 /* setup rest of the bytes if any */
1356                 for (i = 1; i < cell->bytes; i++) {
1357                         /* Get bits from next byte and shift them towards msb */
1358                         *p |= *b << (BITS_PER_BYTE - bit_offset);
1359
1360                         p = b;
1361                         *b++ >>= bit_offset;
1362                 }
1363         } else {
1364                 /* point to the msb */
1365                 p += cell->bytes - 1;
1366         }
1367
1368         /* result fits in less bytes */
1369         extra = cell->bytes - DIV_ROUND_UP(cell->nbits, BITS_PER_BYTE);
1370         while (--extra >= 0)
1371                 *p-- = 0;
1372
1373         /* clear msb bits if any leftover in the last byte */
1374         *p &= GENMASK((cell->nbits%BITS_PER_BYTE) - 1, 0);
1375 }
1376
1377 static int __nvmem_cell_read(struct nvmem_device *nvmem,
1378                       struct nvmem_cell *cell,
1379                       void *buf, size_t *len)
1380 {
1381         int rc;
1382
1383         rc = nvmem_reg_read(nvmem, cell->offset, buf, cell->bytes);
1384
1385         if (rc)
1386                 return rc;
1387
1388         /* shift bits in-place */
1389         if (cell->bit_offset || cell->nbits)
1390                 nvmem_shift_read_buffer_in_place(cell, buf);
1391
1392         if (len)
1393                 *len = cell->bytes;
1394
1395         return 0;
1396 }
1397
1398 /**
1399  * nvmem_cell_read() - Read a given nvmem cell
1400  *
1401  * @cell: nvmem cell to be read.
1402  * @len: pointer to length of cell which will be populated on successful read;
1403  *       can be NULL.
1404  *
1405  * Return: ERR_PTR() on error or a valid pointer to a buffer on success. The
1406  * buffer should be freed by the consumer with a kfree().
1407  */
1408 void *nvmem_cell_read(struct nvmem_cell *cell, size_t *len)
1409 {
1410         struct nvmem_device *nvmem = cell->nvmem;
1411         u8 *buf;
1412         int rc;
1413
1414         if (!nvmem)
1415                 return ERR_PTR(-EINVAL);
1416
1417         buf = kzalloc(cell->bytes, GFP_KERNEL);
1418         if (!buf)
1419                 return ERR_PTR(-ENOMEM);
1420
1421         rc = __nvmem_cell_read(nvmem, cell, buf, len);
1422         if (rc) {
1423                 kfree(buf);
1424                 return ERR_PTR(rc);
1425         }
1426
1427         return buf;
1428 }
1429 EXPORT_SYMBOL_GPL(nvmem_cell_read);
1430
1431 static void *nvmem_cell_prepare_write_buffer(struct nvmem_cell *cell,
1432                                              u8 *_buf, int len)
1433 {
1434         struct nvmem_device *nvmem = cell->nvmem;
1435         int i, rc, nbits, bit_offset = cell->bit_offset;
1436         u8 v, *p, *buf, *b, pbyte, pbits;
1437
1438         nbits = cell->nbits;
1439         buf = kzalloc(cell->bytes, GFP_KERNEL);
1440         if (!buf)
1441                 return ERR_PTR(-ENOMEM);
1442
1443         memcpy(buf, _buf, len);
1444         p = b = buf;
1445
1446         if (bit_offset) {
1447                 pbyte = *b;
1448                 *b <<= bit_offset;
1449
1450                 /* setup the first byte with lsb bits from nvmem */
1451                 rc = nvmem_reg_read(nvmem, cell->offset, &v, 1);
1452                 if (rc)
1453                         goto err;
1454                 *b++ |= GENMASK(bit_offset - 1, 0) & v;
1455
1456                 /* setup rest of the byte if any */
1457                 for (i = 1; i < cell->bytes; i++) {
1458                         /* Get last byte bits and shift them towards lsb */
1459                         pbits = pbyte >> (BITS_PER_BYTE - 1 - bit_offset);
1460                         pbyte = *b;
1461                         p = b;
1462                         *b <<= bit_offset;
1463                         *b++ |= pbits;
1464                 }
1465         }
1466
1467         /* if it's not end on byte boundary */
1468         if ((nbits + bit_offset) % BITS_PER_BYTE) {
1469                 /* setup the last byte with msb bits from nvmem */
1470                 rc = nvmem_reg_read(nvmem,
1471                                     cell->offset + cell->bytes - 1, &v, 1);
1472                 if (rc)
1473                         goto err;
1474                 *p |= GENMASK(7, (nbits + bit_offset) % BITS_PER_BYTE) & v;
1475
1476         }
1477
1478         return buf;
1479 err:
1480         kfree(buf);
1481         return ERR_PTR(rc);
1482 }
1483
1484 /**
1485  * nvmem_cell_write() - Write to a given nvmem cell
1486  *
1487  * @cell: nvmem cell to be written.
1488  * @buf: Buffer to be written.
1489  * @len: length of buffer to be written to nvmem cell.
1490  *
1491  * Return: length of bytes written or negative on failure.
1492  */
1493 int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len)
1494 {
1495         struct nvmem_device *nvmem = cell->nvmem;
1496         int rc;
1497
1498         if (!nvmem || nvmem->read_only ||
1499             (cell->bit_offset == 0 && len != cell->bytes))
1500                 return -EINVAL;
1501
1502         if (cell->bit_offset || cell->nbits) {
1503                 buf = nvmem_cell_prepare_write_buffer(cell, buf, len);
1504                 if (IS_ERR(buf))
1505                         return PTR_ERR(buf);
1506         }
1507
1508         rc = nvmem_reg_write(nvmem, cell->offset, buf, cell->bytes);
1509
1510         /* free the tmp buffer */
1511         if (cell->bit_offset || cell->nbits)
1512                 kfree(buf);
1513
1514         if (rc)
1515                 return rc;
1516
1517         return len;
1518 }
1519 EXPORT_SYMBOL_GPL(nvmem_cell_write);
1520
1521 static int nvmem_cell_read_common(struct device *dev, const char *cell_id,
1522                                   void *val, size_t count)
1523 {
1524         struct nvmem_cell *cell;
1525         void *buf;
1526         size_t len;
1527
1528         cell = nvmem_cell_get(dev, cell_id);
1529         if (IS_ERR(cell))
1530                 return PTR_ERR(cell);
1531
1532         buf = nvmem_cell_read(cell, &len);
1533         if (IS_ERR(buf)) {
1534                 nvmem_cell_put(cell);
1535                 return PTR_ERR(buf);
1536         }
1537         if (len != count) {
1538                 kfree(buf);
1539                 nvmem_cell_put(cell);
1540                 return -EINVAL;
1541         }
1542         memcpy(val, buf, count);
1543         kfree(buf);
1544         nvmem_cell_put(cell);
1545
1546         return 0;
1547 }
1548
1549 /**
1550  * nvmem_cell_read_u8() - Read a cell value as a u8
1551  *
1552  * @dev: Device that requests the nvmem cell.
1553  * @cell_id: Name of nvmem cell to read.
1554  * @val: pointer to output value.
1555  *
1556  * Return: 0 on success or negative errno.
1557  */
1558 int nvmem_cell_read_u8(struct device *dev, const char *cell_id, u8 *val)
1559 {
1560         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1561 }
1562 EXPORT_SYMBOL_GPL(nvmem_cell_read_u8);
1563
1564 /**
1565  * nvmem_cell_read_u16() - Read a cell value as a u16
1566  *
1567  * @dev: Device that requests the nvmem cell.
1568  * @cell_id: Name of nvmem cell to read.
1569  * @val: pointer to output value.
1570  *
1571  * Return: 0 on success or negative errno.
1572  */
1573 int nvmem_cell_read_u16(struct device *dev, const char *cell_id, u16 *val)
1574 {
1575         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1576 }
1577 EXPORT_SYMBOL_GPL(nvmem_cell_read_u16);
1578
1579 /**
1580  * nvmem_cell_read_u32() - Read a cell value as a u32
1581  *
1582  * @dev: Device that requests the nvmem cell.
1583  * @cell_id: Name of nvmem cell to read.
1584  * @val: pointer to output value.
1585  *
1586  * Return: 0 on success or negative errno.
1587  */
1588 int nvmem_cell_read_u32(struct device *dev, const char *cell_id, u32 *val)
1589 {
1590         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1591 }
1592 EXPORT_SYMBOL_GPL(nvmem_cell_read_u32);
1593
1594 /**
1595  * nvmem_cell_read_u64() - Read a cell value as a u64
1596  *
1597  * @dev: Device that requests the nvmem cell.
1598  * @cell_id: Name of nvmem cell to read.
1599  * @val: pointer to output value.
1600  *
1601  * Return: 0 on success or negative errno.
1602  */
1603 int nvmem_cell_read_u64(struct device *dev, const char *cell_id, u64 *val)
1604 {
1605         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1606 }
1607 EXPORT_SYMBOL_GPL(nvmem_cell_read_u64);
1608
1609 static void *nvmem_cell_read_variable_common(struct device *dev,
1610                                              const char *cell_id,
1611                                              size_t max_len, size_t *len)
1612 {
1613         struct nvmem_cell *cell;
1614         int nbits;
1615         void *buf;
1616
1617         cell = nvmem_cell_get(dev, cell_id);
1618         if (IS_ERR(cell))
1619                 return cell;
1620
1621         nbits = cell->nbits;
1622         buf = nvmem_cell_read(cell, len);
1623         nvmem_cell_put(cell);
1624         if (IS_ERR(buf))
1625                 return buf;
1626
1627         /*
1628          * If nbits is set then nvmem_cell_read() can significantly exaggerate
1629          * the length of the real data. Throw away the extra junk.
1630          */
1631         if (nbits)
1632                 *len = DIV_ROUND_UP(nbits, 8);
1633
1634         if (*len > max_len) {
1635                 kfree(buf);
1636                 return ERR_PTR(-ERANGE);
1637         }
1638
1639         return buf;
1640 }
1641
1642 /**
1643  * nvmem_cell_read_variable_le_u32() - Read up to 32-bits of data as a little endian number.
1644  *
1645  * @dev: Device that requests the nvmem cell.
1646  * @cell_id: Name of nvmem cell to read.
1647  * @val: pointer to output value.
1648  *
1649  * Return: 0 on success or negative errno.
1650  */
1651 int nvmem_cell_read_variable_le_u32(struct device *dev, const char *cell_id,
1652                                     u32 *val)
1653 {
1654         size_t len;
1655         u8 *buf;
1656         int i;
1657
1658         buf = nvmem_cell_read_variable_common(dev, cell_id, sizeof(*val), &len);
1659         if (IS_ERR(buf))
1660                 return PTR_ERR(buf);
1661
1662         /* Copy w/ implicit endian conversion */
1663         *val = 0;
1664         for (i = 0; i < len; i++)
1665                 *val |= buf[i] << (8 * i);
1666
1667         kfree(buf);
1668
1669         return 0;
1670 }
1671 EXPORT_SYMBOL_GPL(nvmem_cell_read_variable_le_u32);
1672
1673 /**
1674  * nvmem_cell_read_variable_le_u64() - Read up to 64-bits of data as a little endian number.
1675  *
1676  * @dev: Device that requests the nvmem cell.
1677  * @cell_id: Name of nvmem cell to read.
1678  * @val: pointer to output value.
1679  *
1680  * Return: 0 on success or negative errno.
1681  */
1682 int nvmem_cell_read_variable_le_u64(struct device *dev, const char *cell_id,
1683                                     u64 *val)
1684 {
1685         size_t len;
1686         u8 *buf;
1687         int i;
1688
1689         buf = nvmem_cell_read_variable_common(dev, cell_id, sizeof(*val), &len);
1690         if (IS_ERR(buf))
1691                 return PTR_ERR(buf);
1692
1693         /* Copy w/ implicit endian conversion */
1694         *val = 0;
1695         for (i = 0; i < len; i++)
1696                 *val |= buf[i] << (8 * i);
1697
1698         kfree(buf);
1699
1700         return 0;
1701 }
1702 EXPORT_SYMBOL_GPL(nvmem_cell_read_variable_le_u64);
1703
1704 /**
1705  * nvmem_device_cell_read() - Read a given nvmem device and cell
1706  *
1707  * @nvmem: nvmem device to read from.
1708  * @info: nvmem cell info to be read.
1709  * @buf: buffer pointer which will be populated on successful read.
1710  *
1711  * Return: length of successful bytes read on success and negative
1712  * error code on error.
1713  */
1714 ssize_t nvmem_device_cell_read(struct nvmem_device *nvmem,
1715                            struct nvmem_cell_info *info, void *buf)
1716 {
1717         struct nvmem_cell cell;
1718         int rc;
1719         ssize_t len;
1720
1721         if (!nvmem)
1722                 return -EINVAL;
1723
1724         rc = nvmem_cell_info_to_nvmem_cell_nodup(nvmem, info, &cell);
1725         if (rc)
1726                 return rc;
1727
1728         rc = __nvmem_cell_read(nvmem, &cell, buf, &len);
1729         if (rc)
1730                 return rc;
1731
1732         return len;
1733 }
1734 EXPORT_SYMBOL_GPL(nvmem_device_cell_read);
1735
1736 /**
1737  * nvmem_device_cell_write() - Write cell to a given nvmem device
1738  *
1739  * @nvmem: nvmem device to be written to.
1740  * @info: nvmem cell info to be written.
1741  * @buf: buffer to be written to cell.
1742  *
1743  * Return: length of bytes written or negative error code on failure.
1744  */
1745 int nvmem_device_cell_write(struct nvmem_device *nvmem,
1746                             struct nvmem_cell_info *info, void *buf)
1747 {
1748         struct nvmem_cell cell;
1749         int rc;
1750
1751         if (!nvmem)
1752                 return -EINVAL;
1753
1754         rc = nvmem_cell_info_to_nvmem_cell_nodup(nvmem, info, &cell);
1755         if (rc)
1756                 return rc;
1757
1758         return nvmem_cell_write(&cell, buf, cell.bytes);
1759 }
1760 EXPORT_SYMBOL_GPL(nvmem_device_cell_write);
1761
1762 /**
1763  * nvmem_device_read() - Read from a given nvmem device
1764  *
1765  * @nvmem: nvmem device to read from.
1766  * @offset: offset in nvmem device.
1767  * @bytes: number of bytes to read.
1768  * @buf: buffer pointer which will be populated on successful read.
1769  *
1770  * Return: length of successful bytes read on success and negative
1771  * error code on error.
1772  */
1773 int nvmem_device_read(struct nvmem_device *nvmem,
1774                       unsigned int offset,
1775                       size_t bytes, void *buf)
1776 {
1777         int rc;
1778
1779         if (!nvmem)
1780                 return -EINVAL;
1781
1782         rc = nvmem_reg_read(nvmem, offset, buf, bytes);
1783
1784         if (rc)
1785                 return rc;
1786
1787         return bytes;
1788 }
1789 EXPORT_SYMBOL_GPL(nvmem_device_read);
1790
1791 /**
1792  * nvmem_device_write() - Write cell to a given nvmem device
1793  *
1794  * @nvmem: nvmem device to be written to.
1795  * @offset: offset in nvmem device.
1796  * @bytes: number of bytes to write.
1797  * @buf: buffer to be written.
1798  *
1799  * Return: length of bytes written or negative error code on failure.
1800  */
1801 int nvmem_device_write(struct nvmem_device *nvmem,
1802                        unsigned int offset,
1803                        size_t bytes, void *buf)
1804 {
1805         int rc;
1806
1807         if (!nvmem)
1808                 return -EINVAL;
1809
1810         rc = nvmem_reg_write(nvmem, offset, buf, bytes);
1811
1812         if (rc)
1813                 return rc;
1814
1815
1816         return bytes;
1817 }
1818 EXPORT_SYMBOL_GPL(nvmem_device_write);
1819
1820 /**
1821  * nvmem_add_cell_table() - register a table of cell info entries
1822  *
1823  * @table: table of cell info entries
1824  */
1825 void nvmem_add_cell_table(struct nvmem_cell_table *table)
1826 {
1827         mutex_lock(&nvmem_cell_mutex);
1828         list_add_tail(&table->node, &nvmem_cell_tables);
1829         mutex_unlock(&nvmem_cell_mutex);
1830 }
1831 EXPORT_SYMBOL_GPL(nvmem_add_cell_table);
1832
1833 /**
1834  * nvmem_del_cell_table() - remove a previously registered cell info table
1835  *
1836  * @table: table of cell info entries
1837  */
1838 void nvmem_del_cell_table(struct nvmem_cell_table *table)
1839 {
1840         mutex_lock(&nvmem_cell_mutex);
1841         list_del(&table->node);
1842         mutex_unlock(&nvmem_cell_mutex);
1843 }
1844 EXPORT_SYMBOL_GPL(nvmem_del_cell_table);
1845
1846 /**
1847  * nvmem_add_cell_lookups() - register a list of cell lookup entries
1848  *
1849  * @entries: array of cell lookup entries
1850  * @nentries: number of cell lookup entries in the array
1851  */
1852 void nvmem_add_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
1853 {
1854         int i;
1855
1856         mutex_lock(&nvmem_lookup_mutex);
1857         for (i = 0; i < nentries; i++)
1858                 list_add_tail(&entries[i].node, &nvmem_lookup_list);
1859         mutex_unlock(&nvmem_lookup_mutex);
1860 }
1861 EXPORT_SYMBOL_GPL(nvmem_add_cell_lookups);
1862
1863 /**
1864  * nvmem_del_cell_lookups() - remove a list of previously added cell lookup
1865  *                            entries
1866  *
1867  * @entries: array of cell lookup entries
1868  * @nentries: number of cell lookup entries in the array
1869  */
1870 void nvmem_del_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
1871 {
1872         int i;
1873
1874         mutex_lock(&nvmem_lookup_mutex);
1875         for (i = 0; i < nentries; i++)
1876                 list_del(&entries[i].node);
1877         mutex_unlock(&nvmem_lookup_mutex);
1878 }
1879 EXPORT_SYMBOL_GPL(nvmem_del_cell_lookups);
1880
1881 /**
1882  * nvmem_dev_name() - Get the name of a given nvmem device.
1883  *
1884  * @nvmem: nvmem device.
1885  *
1886  * Return: name of the nvmem device.
1887  */
1888 const char *nvmem_dev_name(struct nvmem_device *nvmem)
1889 {
1890         return dev_name(&nvmem->dev);
1891 }
1892 EXPORT_SYMBOL_GPL(nvmem_dev_name);
1893
1894 static int __init nvmem_init(void)
1895 {
1896         return bus_register(&nvmem_bus_type);
1897 }
1898
1899 static void __exit nvmem_exit(void)
1900 {
1901         bus_unregister(&nvmem_bus_type);
1902 }
1903
1904 subsys_initcall(nvmem_init);
1905 module_exit(nvmem_exit);
1906
1907 MODULE_AUTHOR("Srinivas Kandagatla <srinivas.kandagatla@linaro.org");
1908 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com");
1909 MODULE_DESCRIPTION("nvmem Driver Core");
1910 MODULE_LICENSE("GPL v2");