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 || (len < 2 * sizeof(u32))) {
 686                         dev_err(dev, "nvmem: invalid reg on %pOF\n", child);
 687                         return -EINVAL;
 688                 }
 689
 690                 cell = kzalloc(sizeof(*cell), GFP_KERNEL);
 691                 if (!cell)
 692                         return -ENOMEM;
 693
 694                 cell->nvmem = nvmem;
 695                 cell->np = of_node_get(child);
 696                 cell->offset = be32_to_cpup(addr++);
 697                 cell->bytes = be32_to_cpup(addr);
 698                 cell->name = kasprintf(GFP_KERNEL, "%pOFn", child);
 699
 700                 addr = of_get_property(child, "bits", &len);
 701                 if (addr && len == (2 * sizeof(u32))) {
 702                         cell->bit_offset = be32_to_cpup(addr++);
 703                         cell->nbits = be32_to_cpup(addr);
 704                 }
 705
 706                 if (cell->nbits)
 707                         cell->bytes = DIV_ROUND_UP(
 708                                         cell->nbits + cell->bit_offset,
 709                                         BITS_PER_BYTE);
 710
 711                 if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
 712                         dev_err(dev, "cell %s unaligned to nvmem stride %d\n",
 713                                 cell->name, nvmem->stride);
 714                         /* Cells already added will be freed later. */
 715                         kfree_const(cell->name);
 716                         of_node_put(cell->np);
 717                         kfree(cell);
 718                         return -EINVAL;
 719                 }
 720
 721                 nvmem_cell_add(cell);
 722         }
 723
 724         return 0;
 725 }
 726
 727 /**
 728  * nvmem_register() - Register a nvmem device for given nvmem_config.
 729  * Also creates a binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
 730  *
 731  * @config: nvmem device configuration with which nvmem device is created.
 732  *
 733  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
 734  * on success.
 735  */
 736
 737 struct nvmem_device *nvmem_register(const struct nvmem_config *config)
 738 {
 739         struct nvmem_device *nvmem;
 740         int rval;
 741
 742         if (!config->dev)
 743                 return ERR_PTR(-EINVAL);
 744
 745         if (!config->reg_read && !config->reg_write)
 746                 return ERR_PTR(-EINVAL);
 747
 748         nvmem = kzalloc(sizeof(*nvmem), GFP_KERNEL);
 749         if (!nvmem)
 750                 return ERR_PTR(-ENOMEM);
 751
 752         rval  = ida_alloc(&nvmem_ida, GFP_KERNEL);
 753         if (rval < 0) {
 754                 kfree(nvmem);
 755                 return ERR_PTR(rval);
 756         }
 757
 758         if (config->wp_gpio)
 759                 nvmem->wp_gpio = config->wp_gpio;
 760         else
 761                 nvmem->wp_gpio = gpiod_get_optional(config->dev, "wp",
 762                                                     GPIOD_OUT_HIGH);
 763         if (IS_ERR(nvmem->wp_gpio)) {
 764                 ida_free(&nvmem_ida, nvmem->id);
 765                 rval = PTR_ERR(nvmem->wp_gpio);
 766                 kfree(nvmem);
 767                 return ERR_PTR(rval);
 768         }
 769
 770         kref_init(&nvmem->refcnt);
 771         INIT_LIST_HEAD(&nvmem->cells);
 772
 773         nvmem->id = rval;
 774         nvmem->owner = config->owner;
 775         if (!nvmem->owner && config->dev->driver)
 776                 nvmem->owner = config->dev->driver->owner;
 777         nvmem->stride = config->stride ?: 1;
 778         nvmem->word_size = config->word_size ?: 1;
 779         nvmem->size = config->size;
 780         nvmem->dev.type = &nvmem_provider_type;
 781         nvmem->dev.bus = &nvmem_bus_type;
 782         nvmem->dev.parent = config->dev;
 783         nvmem->root_only = config->root_only;
 784         nvmem->priv = config->priv;
 785         nvmem->type = config->type;
 786         nvmem->reg_read = config->reg_read;
 787         nvmem->reg_write = config->reg_write;
 788         nvmem->keepout = config->keepout;
 789         nvmem->nkeepout = config->nkeepout;
 790         if (!config->no_of_node)
 791                 nvmem->dev.of_node = config->dev->of_node;
 792
 793         switch (config->id) {
 794         case NVMEM_DEVID_NONE:
 795                 dev_set_name(&nvmem->dev, "%s", config->name);
 796                 break;
 797         case NVMEM_DEVID_AUTO:
 798                 dev_set_name(&nvmem->dev, "%s%d", config->name, nvmem->id);
 799                 break;
 800         default:
 801                 dev_set_name(&nvmem->dev, "%s%d",
 802                              config->name ? : "nvmem",
 803                              config->name ? config->id : nvmem->id);
 804                 break;
 805         }
 806
 807         nvmem->read_only = device_property_present(config->dev, "read-only") ||
 808                            config->read_only || !nvmem->reg_write;
 809
 810 #ifdef CONFIG_NVMEM_SYSFS
 811         nvmem->dev.groups = nvmem_dev_groups;
 812 #endif
 813
 814         if (nvmem->nkeepout) {
 815                 rval = nvmem_validate_keepouts(nvmem);
 816                 if (rval)
 817                         goto err_put_device;
 818         }
 819
 820         dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
 821
 822         rval = device_register(&nvmem->dev);
 823         if (rval)
 824                 goto err_put_device;
 825
 826         if (config->compat) {
 827                 rval = nvmem_sysfs_setup_compat(nvmem, config);
 828                 if (rval)
 829                         goto err_device_del;
 830         }
 831
 832         if (config->cells) {
 833                 rval = nvmem_add_cells(nvmem, config->cells, config->ncells);
 834                 if (rval)
 835                         goto err_teardown_compat;
 836         }
 837
 838         rval = nvmem_add_cells_from_table(nvmem);
 839         if (rval)
 840                 goto err_remove_cells;
 841
 842         rval = nvmem_add_cells_from_of(nvmem);
 843         if (rval)
 844                 goto err_remove_cells;
 845
 846         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem);
 847
 848         return nvmem;
 849
 850 err_remove_cells:
 851         nvmem_device_remove_all_cells(nvmem);
 852 err_teardown_compat:
 853         if (config->compat)
 854                 nvmem_sysfs_remove_compat(nvmem, config);
 855 err_device_del:
 856         device_del(&nvmem->dev);
 857 err_put_device:
 858         put_device(&nvmem->dev);
 859
 860         return ERR_PTR(rval);
 861 }
 862 EXPORT_SYMBOL_GPL(nvmem_register);
 863
 864 static void nvmem_device_release(struct kref *kref)
 865 {
 866         struct nvmem_device *nvmem;
 867
 868         nvmem = container_of(kref, struct nvmem_device, refcnt);
 869
 870         blocking_notifier_call_chain(&nvmem_notifier, NVMEM_REMOVE, nvmem);
 871
 872         if (nvmem->flags & FLAG_COMPAT)
 873                 device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
 874
 875         nvmem_device_remove_all_cells(nvmem);
 876         device_unregister(&nvmem->dev);
 877 }
 878
 879 /**
 880  * nvmem_unregister() - Unregister previously registered nvmem device
 881  *
 882  * @nvmem: Pointer to previously registered nvmem device.
 883  */
 884 void nvmem_unregister(struct nvmem_device *nvmem)
 885 {
 886         kref_put(&nvmem->refcnt, nvmem_device_release);
 887 }
 888 EXPORT_SYMBOL_GPL(nvmem_unregister);
 889
 890 static void devm_nvmem_release(struct device *dev, void *res)
 891 {
 892         nvmem_unregister(*(struct nvmem_device **)res);
 893 }
 894
 895 /**
 896  * devm_nvmem_register() - Register a managed nvmem device for given
 897  * nvmem_config.
 898  * Also creates a binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
 899  *
 900  * @dev: Device that uses the nvmem device.
 901  * @config: nvmem device configuration with which nvmem device is created.
 902  *
 903  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
 904  * on success.
 905  */
 906 struct nvmem_device *devm_nvmem_register(struct device *dev,
 907                                          const struct nvmem_config *config)
 908 {
 909         struct nvmem_device **ptr, *nvmem;
 910
 911         ptr = devres_alloc(devm_nvmem_release, sizeof(*ptr), GFP_KERNEL);
 912         if (!ptr)
 913                 return ERR_PTR(-ENOMEM);
 914
 915         nvmem = nvmem_register(config);
 916
 917         if (!IS_ERR(nvmem)) {
 918                 *ptr = nvmem;
 919                 devres_add(dev, ptr);
 920         } else {
 921                 devres_free(ptr);
 922         }
 923
 924         return nvmem;
 925 }
 926 EXPORT_SYMBOL_GPL(devm_nvmem_register);
 927
 928 static int devm_nvmem_match(struct device *dev, void *res, void *data)
 929 {
 930         struct nvmem_device **r = res;
 931
 932         return *r == data;
 933 }
 934
 935 /**
 936  * devm_nvmem_unregister() - Unregister previously registered managed nvmem
 937  * device.
 938  *
 939  * @dev: Device that uses the nvmem device.
 940  * @nvmem: Pointer to previously registered nvmem device.
 941  *
 942  * Return: Will be negative on error or zero on success.
 943  */
 944 int devm_nvmem_unregister(struct device *dev, struct nvmem_device *nvmem)
 945 {
 946         return devres_release(dev, devm_nvmem_release, devm_nvmem_match, nvmem);
 947 }
 948 EXPORT_SYMBOL(devm_nvmem_unregister);
 949
 950 static struct nvmem_device *__nvmem_device_get(void *data,
 951                         int (*match)(struct device *dev, const void *data))
 952 {
 953         struct nvmem_device *nvmem = NULL;
 954         struct device *dev;
 955
 956         mutex_lock(&nvmem_mutex);
 957         dev = bus_find_device(&nvmem_bus_type, NULL, data, match);
 958         if (dev)
 959                 nvmem = to_nvmem_device(dev);
 960         mutex_unlock(&nvmem_mutex);
 961         if (!nvmem)
 962                 return ERR_PTR(-EPROBE_DEFER);
 963
 964         if (!try_module_get(nvmem->owner)) {
 965                 dev_err(&nvmem->dev,
 966                         "could not increase module refcount for cell %s\n",
 967                         nvmem_dev_name(nvmem));
 968
 969                 put_device(&nvmem->dev);
 970                 return ERR_PTR(-EINVAL);
 971         }
 972
 973         kref_get(&nvmem->refcnt);
 974
 975         return nvmem;
 976 }
 977
 978 static void __nvmem_device_put(struct nvmem_device *nvmem)
 979 {
 980         put_device(&nvmem->dev);
 981         module_put(nvmem->owner);
 982         kref_put(&nvmem->refcnt, nvmem_device_release);
 983 }
 984
 985 #if IS_ENABLED(CONFIG_OF)
 986 /**
 987  * of_nvmem_device_get() - Get nvmem device from a given id
 988  *
 989  * @np: Device tree node that uses the nvmem device.
 990  * @id: nvmem name from nvmem-names property.
 991  *
 992  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
 993  * on success.
 994  */
 995 struct nvmem_device *of_nvmem_device_get(struct device_node *np, const char *id)
 996 {
 997
 998         struct device_node *nvmem_np;
 999         struct nvmem_device *nvmem;
1000         int index = 0;
1001
1002         if (id)
1003                 index = of_property_match_string(np, "nvmem-names", id);
1004
1005         nvmem_np = of_parse_phandle(np, "nvmem", index);
1006         if (!nvmem_np)
1007                 return ERR_PTR(-ENOENT);
1008
1009         nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
1010         of_node_put(nvmem_np);
1011         return nvmem;
1012 }
1013 EXPORT_SYMBOL_GPL(of_nvmem_device_get);
1014 #endif
1015
1016 /**
1017  * nvmem_device_get() - Get nvmem device from a given id
1018  *
1019  * @dev: Device that uses the nvmem device.
1020  * @dev_name: name of the requested nvmem device.
1021  *
1022  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1023  * on success.
1024  */
1025 struct nvmem_device *nvmem_device_get(struct device *dev, const char *dev_name)
1026 {
1027         if (dev->of_node) { /* try dt first */
1028                 struct nvmem_device *nvmem;
1029
1030                 nvmem = of_nvmem_device_get(dev->of_node, dev_name);
1031
1032                 if (!IS_ERR(nvmem) || PTR_ERR(nvmem) == -EPROBE_DEFER)
1033                         return nvmem;
1034
1035         }
1036
1037         return __nvmem_device_get((void *)dev_name, device_match_name);
1038 }
1039 EXPORT_SYMBOL_GPL(nvmem_device_get);
1040
1041 /**
1042  * nvmem_device_find() - Find nvmem device with matching function
1043  *
1044  * @data: Data to pass to match function
1045  * @match: Callback function to check device
1046  *
1047  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1048  * on success.
1049  */
1050 struct nvmem_device *nvmem_device_find(void *data,
1051                         int (*match)(struct device *dev, const void *data))
1052 {
1053         return __nvmem_device_get(data, match);
1054 }
1055 EXPORT_SYMBOL_GPL(nvmem_device_find);
1056
1057 static int devm_nvmem_device_match(struct device *dev, void *res, void *data)
1058 {
1059         struct nvmem_device **nvmem = res;
1060
1061         if (WARN_ON(!nvmem || !*nvmem))
1062                 return 0;
1063
1064         return *nvmem == data;
1065 }
1066
1067 static void devm_nvmem_device_release(struct device *dev, void *res)
1068 {
1069         nvmem_device_put(*(struct nvmem_device **)res);
1070 }
1071
1072 /**
1073  * devm_nvmem_device_put() - put alredy got nvmem device
1074  *
1075  * @dev: Device that uses the nvmem device.
1076  * @nvmem: pointer to nvmem device allocated by devm_nvmem_cell_get(),
1077  * that needs to be released.
1078  */
1079 void devm_nvmem_device_put(struct device *dev, struct nvmem_device *nvmem)
1080 {
1081         int ret;
1082
1083         ret = devres_release(dev, devm_nvmem_device_release,
1084                              devm_nvmem_device_match, nvmem);
1085
1086         WARN_ON(ret);
1087 }
1088 EXPORT_SYMBOL_GPL(devm_nvmem_device_put);
1089
1090 /**
1091  * nvmem_device_put() - put alredy got nvmem device
1092  *
1093  * @nvmem: pointer to nvmem device that needs to be released.
1094  */
1095 void nvmem_device_put(struct nvmem_device *nvmem)
1096 {
1097         __nvmem_device_put(nvmem);
1098 }
1099 EXPORT_SYMBOL_GPL(nvmem_device_put);
1100
1101 /**
1102  * devm_nvmem_device_get() - Get nvmem cell of device form a given id
1103  *
1104  * @dev: Device that requests the nvmem device.
1105  * @id: name id for the requested nvmem device.
1106  *
1107  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_cell
1108  * on success.  The nvmem_cell will be freed by the automatically once the
1109  * device is freed.
1110  */
1111 struct nvmem_device *devm_nvmem_device_get(struct device *dev, const char *id)
1112 {
1113         struct nvmem_device **ptr, *nvmem;
1114
1115         ptr = devres_alloc(devm_nvmem_device_release, sizeof(*ptr), GFP_KERNEL);
1116         if (!ptr)
1117                 return ERR_PTR(-ENOMEM);
1118
1119         nvmem = nvmem_device_get(dev, id);
1120         if (!IS_ERR(nvmem)) {
1121                 *ptr = nvmem;
1122                 devres_add(dev, ptr);
1123         } else {
1124                 devres_free(ptr);
1125         }
1126
1127         return nvmem;
1128 }
1129 EXPORT_SYMBOL_GPL(devm_nvmem_device_get);
1130
1131 static struct nvmem_cell *
1132 nvmem_cell_get_from_lookup(struct device *dev, const char *con_id)
1133 {
1134         struct nvmem_cell *cell = ERR_PTR(-ENOENT);
1135         struct nvmem_cell_lookup *lookup;
1136         struct nvmem_device *nvmem;
1137         const char *dev_id;
1138
1139         if (!dev)
1140                 return ERR_PTR(-EINVAL);
1141
1142         dev_id = dev_name(dev);
1143
1144         mutex_lock(&nvmem_lookup_mutex);
1145
1146         list_for_each_entry(lookup, &nvmem_lookup_list, node) {
1147                 if ((strcmp(lookup->dev_id, dev_id) == 0) &&
1148                     (strcmp(lookup->con_id, con_id) == 0)) {
1149                         /* This is the right entry. */
1150                         nvmem = __nvmem_device_get((void *)lookup->nvmem_name,
1151                                                    device_match_name);
1152                         if (IS_ERR(nvmem)) {
1153                                 /* Provider may not be registered yet. */
1154                                 cell = ERR_CAST(nvmem);
1155                                 break;
1156                         }
1157
1158                         cell = nvmem_find_cell_by_name(nvmem,
1159                                                        lookup->cell_name);
1160                         if (!cell) {
1161                                 __nvmem_device_put(nvmem);
1162                                 cell = ERR_PTR(-ENOENT);
1163                         }
1164                         break;
1165                 }
1166         }
1167
1168         mutex_unlock(&nvmem_lookup_mutex);
1169         return cell;
1170 }
1171
1172 #if IS_ENABLED(CONFIG_OF)
1173 static struct nvmem_cell *
1174 nvmem_find_cell_by_node(struct nvmem_device *nvmem, struct device_node *np)
1175 {
1176         struct nvmem_cell *iter, *cell = NULL;
1177
1178         mutex_lock(&nvmem_mutex);
1179         list_for_each_entry(iter, &nvmem->cells, node) {
1180                 if (np == iter->np) {
1181                         cell = iter;
1182                         break;
1183                 }
1184         }
1185         mutex_unlock(&nvmem_mutex);
1186
1187         return cell;
1188 }
1189
1190 /**
1191  * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
1192  *
1193  * @np: Device tree node that uses the nvmem cell.
1194  * @id: nvmem cell name from nvmem-cell-names property, or NULL
1195  *      for the cell at index 0 (the lone cell with no accompanying
1196  *      nvmem-cell-names property).
1197  *
1198  * Return: Will be an ERR_PTR() on error or a valid pointer
1199  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1200  * nvmem_cell_put().
1201  */
1202 struct nvmem_cell *of_nvmem_cell_get(struct device_node *np, const char *id)
1203 {
1204         struct device_node *cell_np, *nvmem_np;
1205         struct nvmem_device *nvmem;
1206         struct nvmem_cell *cell;
1207         int index = 0;
1208
1209         /* if cell name exists, find index to the name */
1210         if (id)
1211                 index = of_property_match_string(np, "nvmem-cell-names", id);
1212
1213         cell_np = of_parse_phandle(np, "nvmem-cells", index);
1214         if (!cell_np)
1215                 return ERR_PTR(-ENOENT);
1216
1217         nvmem_np = of_get_next_parent(cell_np);
1218         if (!nvmem_np)
1219                 return ERR_PTR(-EINVAL);
1220
1221         nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
1222         of_node_put(nvmem_np);
1223         if (IS_ERR(nvmem))
1224                 return ERR_CAST(nvmem);
1225
1226         cell = nvmem_find_cell_by_node(nvmem, cell_np);
1227         if (!cell) {
1228                 __nvmem_device_put(nvmem);
1229                 return ERR_PTR(-ENOENT);
1230         }
1231
1232         return cell;
1233 }
1234 EXPORT_SYMBOL_GPL(of_nvmem_cell_get);
1235 #endif
1236
1237 /**
1238  * nvmem_cell_get() - Get nvmem cell of device form a given cell name
1239  *
1240  * @dev: Device that requests the nvmem cell.
1241  * @id: nvmem cell name to get (this corresponds with the name from the
1242  *      nvmem-cell-names property for DT systems and with the con_id from
1243  *      the lookup entry for non-DT systems).
1244  *
1245  * Return: Will be an ERR_PTR() on error or a valid pointer
1246  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1247  * nvmem_cell_put().
1248  */
1249 struct nvmem_cell *nvmem_cell_get(struct device *dev, const char *id)
1250 {
1251         struct nvmem_cell *cell;
1252
1253         if (dev->of_node) { /* try dt first */
1254                 cell = of_nvmem_cell_get(dev->of_node, id);
1255                 if (!IS_ERR(cell) || PTR_ERR(cell) == -EPROBE_DEFER)
1256                         return cell;
1257         }
1258
1259         /* NULL cell id only allowed for device tree; invalid otherwise */
1260         if (!id)
1261                 return ERR_PTR(-EINVAL);
1262
1263         return nvmem_cell_get_from_lookup(dev, id);
1264 }
1265 EXPORT_SYMBOL_GPL(nvmem_cell_get);
1266
1267 static void devm_nvmem_cell_release(struct device *dev, void *res)
1268 {
1269         nvmem_cell_put(*(struct nvmem_cell **)res);
1270 }
1271
1272 /**
1273  * devm_nvmem_cell_get() - Get nvmem cell of device form a given id
1274  *
1275  * @dev: Device that requests the nvmem cell.
1276  * @id: nvmem cell name id to get.
1277  *
1278  * Return: Will be an ERR_PTR() on error or a valid pointer
1279  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1280  * automatically once the device is freed.
1281  */
1282 struct nvmem_cell *devm_nvmem_cell_get(struct device *dev, const char *id)
1283 {
1284         struct nvmem_cell **ptr, *cell;
1285
1286         ptr = devres_alloc(devm_nvmem_cell_release, sizeof(*ptr), GFP_KERNEL);
1287         if (!ptr)
1288                 return ERR_PTR(-ENOMEM);
1289
1290         cell = nvmem_cell_get(dev, id);
1291         if (!IS_ERR(cell)) {
1292                 *ptr = cell;
1293                 devres_add(dev, ptr);
1294         } else {
1295                 devres_free(ptr);
1296         }
1297
1298         return cell;
1299 }
1300 EXPORT_SYMBOL_GPL(devm_nvmem_cell_get);
1301
1302 static int devm_nvmem_cell_match(struct device *dev, void *res, void *data)
1303 {
1304         struct nvmem_cell **c = res;
1305
1306         if (WARN_ON(!c || !*c))
1307                 return 0;
1308
1309         return *c == data;
1310 }
1311
1312 /**
1313  * devm_nvmem_cell_put() - Release previously allocated nvmem cell
1314  * from devm_nvmem_cell_get.
1315  *
1316  * @dev: Device that requests the nvmem cell.
1317  * @cell: Previously allocated nvmem cell by devm_nvmem_cell_get().
1318  */
1319 void devm_nvmem_cell_put(struct device *dev, struct nvmem_cell *cell)
1320 {
1321         int ret;
1322
1323         ret = devres_release(dev, devm_nvmem_cell_release,
1324                                 devm_nvmem_cell_match, cell);
1325
1326         WARN_ON(ret);
1327 }
1328 EXPORT_SYMBOL(devm_nvmem_cell_put);
1329
1330 /**
1331  * nvmem_cell_put() - Release previously allocated nvmem cell.
1332  *
1333  * @cell: Previously allocated nvmem cell by nvmem_cell_get().
1334  */
1335 void nvmem_cell_put(struct nvmem_cell *cell)
1336 {
1337         struct nvmem_device *nvmem = cell->nvmem;
1338
1339         __nvmem_device_put(nvmem);
1340 }
1341 EXPORT_SYMBOL_GPL(nvmem_cell_put);
1342
1343 static void nvmem_shift_read_buffer_in_place(struct nvmem_cell *cell, void *buf)
1344 {
1345         u8 *p, *b;
1346         int i, extra, bit_offset = cell->bit_offset;
1347
1348         p = b = buf;
1349         if (bit_offset) {
1350                 /* First shift */
1351                 *b++ >>= bit_offset;
1352
1353                 /* setup rest of the bytes if any */
1354                 for (i = 1; i < cell->bytes; i++) {
1355                         /* Get bits from next byte and shift them towards msb */
1356                         *p |= *b << (BITS_PER_BYTE - bit_offset);
1357
1358                         p = b;
1359                         *b++ >>= bit_offset;
1360                 }
1361         } else {
1362                 /* point to the msb */
1363                 p += cell->bytes - 1;
1364         }
1365
1366         /* result fits in less bytes */
1367         extra = cell->bytes - DIV_ROUND_UP(cell->nbits, BITS_PER_BYTE);
1368         while (--extra >= 0)
1369                 *p-- = 0;
1370
1371         /* clear msb bits if any leftover in the last byte */
1372         *p &= GENMASK((cell->nbits%BITS_PER_BYTE) - 1, 0);
1373 }
1374
1375 static int __nvmem_cell_read(struct nvmem_device *nvmem,
1376                       struct nvmem_cell *cell,
1377                       void *buf, size_t *len)
1378 {
1379         int rc;
1380
1381         rc = nvmem_reg_read(nvmem, cell->offset, buf, cell->bytes);
1382
1383         if (rc)
1384                 return rc;
1385
1386         /* shift bits in-place */
1387         if (cell->bit_offset || cell->nbits)
1388                 nvmem_shift_read_buffer_in_place(cell, buf);
1389
1390         if (len)
1391                 *len = cell->bytes;
1392
1393         return 0;
1394 }
1395
1396 /**
1397  * nvmem_cell_read() - Read a given nvmem cell
1398  *
1399  * @cell: nvmem cell to be read.
1400  * @len: pointer to length of cell which will be populated on successful read;
1401  *       can be NULL.
1402  *
1403  * Return: ERR_PTR() on error or a valid pointer to a buffer on success. The
1404  * buffer should be freed by the consumer with a kfree().
1405  */
1406 void *nvmem_cell_read(struct nvmem_cell *cell, size_t *len)
1407 {
1408         struct nvmem_device *nvmem = cell->nvmem;
1409         u8 *buf;
1410         int rc;
1411
1412         if (!nvmem)
1413                 return ERR_PTR(-EINVAL);
1414
1415         buf = kzalloc(cell->bytes, GFP_KERNEL);
1416         if (!buf)
1417                 return ERR_PTR(-ENOMEM);
1418
1419         rc = __nvmem_cell_read(nvmem, cell, buf, len);
1420         if (rc) {
1421                 kfree(buf);
1422                 return ERR_PTR(rc);
1423         }
1424
1425         return buf;
1426 }
1427 EXPORT_SYMBOL_GPL(nvmem_cell_read);
1428
1429 static void *nvmem_cell_prepare_write_buffer(struct nvmem_cell *cell,
1430                                              u8 *_buf, int len)
1431 {
1432         struct nvmem_device *nvmem = cell->nvmem;
1433         int i, rc, nbits, bit_offset = cell->bit_offset;
1434         u8 v, *p, *buf, *b, pbyte, pbits;
1435
1436         nbits = cell->nbits;
1437         buf = kzalloc(cell->bytes, GFP_KERNEL);
1438         if (!buf)
1439                 return ERR_PTR(-ENOMEM);
1440
1441         memcpy(buf, _buf, len);
1442         p = b = buf;
1443
1444         if (bit_offset) {
1445                 pbyte = *b;
1446                 *b <<= bit_offset;
1447
1448                 /* setup the first byte with lsb bits from nvmem */
1449                 rc = nvmem_reg_read(nvmem, cell->offset, &v, 1);
1450                 if (rc)
1451                         goto err;
1452                 *b++ |= GENMASK(bit_offset - 1, 0) & v;
1453
1454                 /* setup rest of the byte if any */
1455                 for (i = 1; i < cell->bytes; i++) {
1456                         /* Get last byte bits and shift them towards lsb */
1457                         pbits = pbyte >> (BITS_PER_BYTE - 1 - bit_offset);
1458                         pbyte = *b;
1459                         p = b;
1460                         *b <<= bit_offset;
1461                         *b++ |= pbits;
1462                 }
1463         }
1464
1465         /* if it's not end on byte boundary */
1466         if ((nbits + bit_offset) % BITS_PER_BYTE) {
1467                 /* setup the last byte with msb bits from nvmem */
1468                 rc = nvmem_reg_read(nvmem,
1469                                     cell->offset + cell->bytes - 1, &v, 1);
1470                 if (rc)
1471                         goto err;
1472                 *p |= GENMASK(7, (nbits + bit_offset) % BITS_PER_BYTE) & v;
1473
1474         }
1475
1476         return buf;
1477 err:
1478         kfree(buf);
1479         return ERR_PTR(rc);
1480 }
1481
1482 /**
1483  * nvmem_cell_write() - Write to a given nvmem cell
1484  *
1485  * @cell: nvmem cell to be written.
1486  * @buf: Buffer to be written.
1487  * @len: length of buffer to be written to nvmem cell.
1488  *
1489  * Return: length of bytes written or negative on failure.
1490  */
1491 int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len)
1492 {
1493         struct nvmem_device *nvmem = cell->nvmem;
1494         int rc;
1495
1496         if (!nvmem || nvmem->read_only ||
1497             (cell->bit_offset == 0 && len != cell->bytes))
1498                 return -EINVAL;
1499
1500         if (cell->bit_offset || cell->nbits) {
1501                 buf = nvmem_cell_prepare_write_buffer(cell, buf, len);
1502                 if (IS_ERR(buf))
1503                         return PTR_ERR(buf);
1504         }
1505
1506         rc = nvmem_reg_write(nvmem, cell->offset, buf, cell->bytes);
1507
1508         /* free the tmp buffer */
1509         if (cell->bit_offset || cell->nbits)
1510                 kfree(buf);
1511
1512         if (rc)
1513                 return rc;
1514
1515         return len;
1516 }
1517 EXPORT_SYMBOL_GPL(nvmem_cell_write);
1518
1519 static int nvmem_cell_read_common(struct device *dev, const char *cell_id,
1520                                   void *val, size_t count)
1521 {
1522         struct nvmem_cell *cell;
1523         void *buf;
1524         size_t len;
1525
1526         cell = nvmem_cell_get(dev, cell_id);
1527         if (IS_ERR(cell))
1528                 return PTR_ERR(cell);
1529
1530         buf = nvmem_cell_read(cell, &len);
1531         if (IS_ERR(buf)) {
1532                 nvmem_cell_put(cell);
1533                 return PTR_ERR(buf);
1534         }
1535         if (len != count) {
1536                 kfree(buf);
1537                 nvmem_cell_put(cell);
1538                 return -EINVAL;
1539         }
1540         memcpy(val, buf, count);
1541         kfree(buf);
1542         nvmem_cell_put(cell);
1543
1544         return 0;
1545 }
1546
1547 /**
1548  * nvmem_cell_read_u8() - Read a cell value as a u8
1549  *
1550  * @dev: Device that requests the nvmem cell.
1551  * @cell_id: Name of nvmem cell to read.
1552  * @val: pointer to output value.
1553  *
1554  * Return: 0 on success or negative errno.
1555  */
1556 int nvmem_cell_read_u8(struct device *dev, const char *cell_id, u8 *val)
1557 {
1558         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1559 }
1560 EXPORT_SYMBOL_GPL(nvmem_cell_read_u8);
1561
1562 /**
1563  * nvmem_cell_read_u16() - Read a cell value as a u16
1564  *
1565  * @dev: Device that requests the nvmem cell.
1566  * @cell_id: Name of nvmem cell to read.
1567  * @val: pointer to output value.
1568  *
1569  * Return: 0 on success or negative errno.
1570  */
1571 int nvmem_cell_read_u16(struct device *dev, const char *cell_id, u16 *val)
1572 {
1573         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1574 }
1575 EXPORT_SYMBOL_GPL(nvmem_cell_read_u16);
1576
1577 /**
1578  * nvmem_cell_read_u32() - Read a cell value as a u32
1579  *
1580  * @dev: Device that requests the nvmem cell.
1581  * @cell_id: Name of nvmem cell to read.
1582  * @val: pointer to output value.
1583  *
1584  * Return: 0 on success or negative errno.
1585  */
1586 int nvmem_cell_read_u32(struct device *dev, const char *cell_id, u32 *val)
1587 {
1588         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1589 }
1590 EXPORT_SYMBOL_GPL(nvmem_cell_read_u32);
1591
1592 /**
1593  * nvmem_cell_read_u64() - Read a cell value as a u64
1594  *
1595  * @dev: Device that requests the nvmem cell.
1596  * @cell_id: Name of nvmem cell to read.
1597  * @val: pointer to output value.
1598  *
1599  * Return: 0 on success or negative errno.
1600  */
1601 int nvmem_cell_read_u64(struct device *dev, const char *cell_id, u64 *val)
1602 {
1603         return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1604 }
1605 EXPORT_SYMBOL_GPL(nvmem_cell_read_u64);
1606
1607 /**
1608  * nvmem_device_cell_read() - Read a given nvmem device and cell
1609  *
1610  * @nvmem: nvmem device to read from.
1611  * @info: nvmem cell info to be read.
1612  * @buf: buffer pointer which will be populated on successful read.
1613  *
1614  * Return: length of successful bytes read on success and negative
1615  * error code on error.
1616  */
1617 ssize_t nvmem_device_cell_read(struct nvmem_device *nvmem,
1618                            struct nvmem_cell_info *info, void *buf)
1619 {
1620         struct nvmem_cell cell;
1621         int rc;
1622         ssize_t len;
1623
1624         if (!nvmem)
1625                 return -EINVAL;
1626
1627         rc = nvmem_cell_info_to_nvmem_cell_nodup(nvmem, info, &cell);
1628         if (rc)
1629                 return rc;
1630
1631         rc = __nvmem_cell_read(nvmem, &cell, buf, &len);
1632         if (rc)
1633                 return rc;
1634
1635         return len;
1636 }
1637 EXPORT_SYMBOL_GPL(nvmem_device_cell_read);
1638
1639 /**
1640  * nvmem_device_cell_write() - Write cell to a given nvmem device
1641  *
1642  * @nvmem: nvmem device to be written to.
1643  * @info: nvmem cell info to be written.
1644  * @buf: buffer to be written to cell.
1645  *
1646  * Return: length of bytes written or negative error code on failure.
1647  */
1648 int nvmem_device_cell_write(struct nvmem_device *nvmem,
1649                             struct nvmem_cell_info *info, void *buf)
1650 {
1651         struct nvmem_cell cell;
1652         int rc;
1653
1654         if (!nvmem)
1655                 return -EINVAL;
1656
1657         rc = nvmem_cell_info_to_nvmem_cell_nodup(nvmem, info, &cell);
1658         if (rc)
1659                 return rc;
1660
1661         return nvmem_cell_write(&cell, buf, cell.bytes);
1662 }
1663 EXPORT_SYMBOL_GPL(nvmem_device_cell_write);
1664
1665 /**
1666  * nvmem_device_read() - Read from a given nvmem device
1667  *
1668  * @nvmem: nvmem device to read from.
1669  * @offset: offset in nvmem device.
1670  * @bytes: number of bytes to read.
1671  * @buf: buffer pointer which will be populated on successful read.
1672  *
1673  * Return: length of successful bytes read on success and negative
1674  * error code on error.
1675  */
1676 int nvmem_device_read(struct nvmem_device *nvmem,
1677                       unsigned int offset,
1678                       size_t bytes, void *buf)
1679 {
1680         int rc;
1681
1682         if (!nvmem)
1683                 return -EINVAL;
1684
1685         rc = nvmem_reg_read(nvmem, offset, buf, bytes);
1686
1687         if (rc)
1688                 return rc;
1689
1690         return bytes;
1691 }
1692 EXPORT_SYMBOL_GPL(nvmem_device_read);
1693
1694 /**
1695  * nvmem_device_write() - Write cell to a given nvmem device
1696  *
1697  * @nvmem: nvmem device to be written to.
1698  * @offset: offset in nvmem device.
1699  * @bytes: number of bytes to write.
1700  * @buf: buffer to be written.
1701  *
1702  * Return: length of bytes written or negative error code on failure.
1703  */
1704 int nvmem_device_write(struct nvmem_device *nvmem,
1705                        unsigned int offset,
1706                        size_t bytes, void *buf)
1707 {
1708         int rc;
1709
1710         if (!nvmem)
1711                 return -EINVAL;
1712
1713         rc = nvmem_reg_write(nvmem, offset, buf, bytes);
1714
1715         if (rc)
1716                 return rc;
1717
1718
1719         return bytes;
1720 }
1721 EXPORT_SYMBOL_GPL(nvmem_device_write);
1722
1723 /**
1724  * nvmem_add_cell_table() - register a table of cell info entries
1725  *
1726  * @table: table of cell info entries
1727  */
1728 void nvmem_add_cell_table(struct nvmem_cell_table *table)
1729 {
1730         mutex_lock(&nvmem_cell_mutex);
1731         list_add_tail(&table->node, &nvmem_cell_tables);
1732         mutex_unlock(&nvmem_cell_mutex);
1733 }
1734 EXPORT_SYMBOL_GPL(nvmem_add_cell_table);
1735
1736 /**
1737  * nvmem_del_cell_table() - remove a previously registered cell info table
1738  *
1739  * @table: table of cell info entries
1740  */
1741 void nvmem_del_cell_table(struct nvmem_cell_table *table)
1742 {
1743         mutex_lock(&nvmem_cell_mutex);
1744         list_del(&table->node);
1745         mutex_unlock(&nvmem_cell_mutex);
1746 }
1747 EXPORT_SYMBOL_GPL(nvmem_del_cell_table);
1748
1749 /**
1750  * nvmem_add_cell_lookups() - register a list of cell lookup entries
1751  *
1752  * @entries: array of cell lookup entries
1753  * @nentries: number of cell lookup entries in the array
1754  */
1755 void nvmem_add_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
1756 {
1757         int i;
1758
1759         mutex_lock(&nvmem_lookup_mutex);
1760         for (i = 0; i < nentries; i++)
1761                 list_add_tail(&entries[i].node, &nvmem_lookup_list);
1762         mutex_unlock(&nvmem_lookup_mutex);
1763 }
1764 EXPORT_SYMBOL_GPL(nvmem_add_cell_lookups);
1765
1766 /**
1767  * nvmem_del_cell_lookups() - remove a list of previously added cell lookup
1768  *                            entries
1769  *
1770  * @entries: array of cell lookup entries
1771  * @nentries: number of cell lookup entries in the array
1772  */
1773 void nvmem_del_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
1774 {
1775         int i;
1776
1777         mutex_lock(&nvmem_lookup_mutex);
1778         for (i = 0; i < nentries; i++)
1779                 list_del(&entries[i].node);
1780         mutex_unlock(&nvmem_lookup_mutex);
1781 }
1782 EXPORT_SYMBOL_GPL(nvmem_del_cell_lookups);
1783
1784 /**
1785  * nvmem_dev_name() - Get the name of a given nvmem device.
1786  *
1787  * @nvmem: nvmem device.
1788  *
1789  * Return: name of the nvmem device.
1790  */
1791 const char *nvmem_dev_name(struct nvmem_device *nvmem)
1792 {
1793         return dev_name(&nvmem->dev);
1794 }
1795 EXPORT_SYMBOL_GPL(nvmem_dev_name);
1796
1797 static int __init nvmem_init(void)
1798 {
1799         return bus_register(&nvmem_bus_type);
1800 }
1801
1802 static void __exit nvmem_exit(void)
1803 {
1804         bus_unregister(&nvmem_bus_type);
1805 }
1806
1807 subsys_initcall(nvmem_init);
1808 module_exit(nvmem_exit);
1809
1810 MODULE_AUTHOR("Srinivas Kandagatla <srinivas.kandagatla@linaro.org");
1811 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com");
1812 MODULE_DESCRIPTION("nvmem Driver Core");
1813 MODULE_LICENSE("GPL v2");