drivers/nvmem/core.c

   1 /*
   2  * nvmem framework core.
   3  *
   4  * Copyright (C) 2015 Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
   5  * Copyright (C) 2013 Maxime Ripard <maxime.ripard@free-electrons.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 and
   9  * only version 2 as published by the Free Software Foundation.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  */
  16
  17 #include <linux/device.h>
  18 #include <linux/export.h>
  19 #include <linux/fs.h>
  20 #include <linux/idr.h>
  21 #include <linux/init.h>
  22 #include <linux/module.h>
  23 #include <linux/nvmem-consumer.h>
  24 #include <linux/nvmem-provider.h>
  25 #include <linux/of.h>
  26 #include <linux/slab.h>
  27
  28 struct nvmem_device {
  29         const char              *name;
  30         struct module           *owner;
  31         struct device           dev;
  32         int                     stride;
  33         int                     word_size;
  34         int                     ncells;
  35         int                     id;
  36         int                     users;
  37         size_t                  size;
  38         bool                    read_only;
  39         int                     flags;
  40         struct bin_attribute    eeprom;
  41         struct device           *base_dev;
  42         nvmem_reg_read_t        reg_read;
  43         nvmem_reg_write_t       reg_write;
  44         void *priv;
  45 };
  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 nvmem_device     *nvmem;
  56         struct list_head        node;
  57 };
  58
  59 static DEFINE_MUTEX(nvmem_mutex);
  60 static DEFINE_IDA(nvmem_ida);
  61
  62 static LIST_HEAD(nvmem_cells);
  63 static DEFINE_MUTEX(nvmem_cells_mutex);
  64
  65 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  66 static struct lock_class_key eeprom_lock_key;
  67 #endif
  68
  69 #define to_nvmem_device(d) container_of(d, struct nvmem_device, dev)
  70 static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
  71                           void *val, size_t bytes)
  72 {
  73         if (nvmem->reg_read)
  74                 return nvmem->reg_read(nvmem->priv, offset, val, bytes);
  75
  76         return -EINVAL;
  77 }
  78
  79 static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
  80                            void *val, size_t bytes)
  81 {
  82         if (nvmem->reg_write)
  83                 return nvmem->reg_write(nvmem->priv, offset, val, bytes);
  84
  85         return -EINVAL;
  86 }
  87
  88 static ssize_t bin_attr_nvmem_read(struct file *filp, struct kobject *kobj,
  89                                     struct bin_attribute *attr,
  90                                     char *buf, loff_t pos, size_t count)
  91 {
  92         struct device *dev;
  93         struct nvmem_device *nvmem;
  94         int rc;
  95
  96         if (attr->private)
  97                 dev = attr->private;
  98         else
  99                 dev = container_of(kobj, struct device, kobj);
 100         nvmem = to_nvmem_device(dev);
 101
 102         /* Stop the user from reading */
 103         if (pos >= nvmem->size)
 104                 return 0;
 105
 106         if (count < nvmem->word_size)
 107                 return -EINVAL;
 108
 109         if (pos + count > nvmem->size)
 110                 count = nvmem->size - pos;
 111
 112         count = round_down(count, nvmem->word_size);
 113
 114         rc = nvmem_reg_read(nvmem, pos, buf, count);
 115
 116         if (rc)
 117                 return rc;
 118
 119         return count;
 120 }
 121
 122 static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj,
 123                                      struct bin_attribute *attr,
 124                                      char *buf, loff_t pos, size_t count)
 125 {
 126         struct device *dev;
 127         struct nvmem_device *nvmem;
 128         int rc;
 129
 130         if (attr->private)
 131                 dev = attr->private;
 132         else
 133                 dev = container_of(kobj, struct device, kobj);
 134         nvmem = to_nvmem_device(dev);
 135
 136         /* Stop the user from writing */
 137         if (pos >= nvmem->size)
 138                 return 0;
 139
 140         if (count < nvmem->word_size)
 141                 return -EINVAL;
 142
 143         if (pos + count > nvmem->size)
 144                 count = nvmem->size - pos;
 145
 146         count = round_down(count, nvmem->word_size);
 147
 148         rc = nvmem_reg_write(nvmem, pos, buf, count);
 149
 150         if (rc)
 151                 return rc;
 152
 153         return count;
 154 }
 155
 156 /* default read/write permissions */
 157 static struct bin_attribute bin_attr_rw_nvmem = {
 158         .attr   = {
 159                 .name   = "nvmem",
 160                 .mode   = S_IWUSR | S_IRUGO,
 161         },
 162         .read   = bin_attr_nvmem_read,
 163         .write  = bin_attr_nvmem_write,
 164 };
 165
 166 static struct bin_attribute *nvmem_bin_rw_attributes[] = {
 167         &bin_attr_rw_nvmem,
 168         NULL,
 169 };
 170
 171 static const struct attribute_group nvmem_bin_rw_group = {
 172         .bin_attrs      = nvmem_bin_rw_attributes,
 173 };
 174
 175 static const struct attribute_group *nvmem_rw_dev_groups[] = {
 176         &nvmem_bin_rw_group,
 177         NULL,
 178 };
 179
 180 /* read only permission */
 181 static struct bin_attribute bin_attr_ro_nvmem = {
 182         .attr   = {
 183                 .name   = "nvmem",
 184                 .mode   = S_IRUGO,
 185         },
 186         .read   = bin_attr_nvmem_read,
 187 };
 188
 189 static struct bin_attribute *nvmem_bin_ro_attributes[] = {
 190         &bin_attr_ro_nvmem,
 191         NULL,
 192 };
 193
 194 static const struct attribute_group nvmem_bin_ro_group = {
 195         .bin_attrs      = nvmem_bin_ro_attributes,
 196 };
 197
 198 static const struct attribute_group *nvmem_ro_dev_groups[] = {
 199         &nvmem_bin_ro_group,
 200         NULL,
 201 };
 202
 203 /* default read/write permissions, root only */
 204 static struct bin_attribute bin_attr_rw_root_nvmem = {
 205         .attr   = {
 206                 .name   = "nvmem",
 207                 .mode   = S_IWUSR | S_IRUSR,
 208         },
 209         .read   = bin_attr_nvmem_read,
 210         .write  = bin_attr_nvmem_write,
 211 };
 212
 213 static struct bin_attribute *nvmem_bin_rw_root_attributes[] = {
 214         &bin_attr_rw_root_nvmem,
 215         NULL,
 216 };
 217
 218 static const struct attribute_group nvmem_bin_rw_root_group = {
 219         .bin_attrs      = nvmem_bin_rw_root_attributes,
 220 };
 221
 222 static const struct attribute_group *nvmem_rw_root_dev_groups[] = {
 223         &nvmem_bin_rw_root_group,
 224         NULL,
 225 };
 226
 227 /* read only permission, root only */
 228 static struct bin_attribute bin_attr_ro_root_nvmem = {
 229         .attr   = {
 230                 .name   = "nvmem",
 231                 .mode   = S_IRUSR,
 232         },
 233         .read   = bin_attr_nvmem_read,
 234 };
 235
 236 static struct bin_attribute *nvmem_bin_ro_root_attributes[] = {
 237         &bin_attr_ro_root_nvmem,
 238         NULL,
 239 };
 240
 241 static const struct attribute_group nvmem_bin_ro_root_group = {
 242         .bin_attrs      = nvmem_bin_ro_root_attributes,
 243 };
 244
 245 static const struct attribute_group *nvmem_ro_root_dev_groups[] = {
 246         &nvmem_bin_ro_root_group,
 247         NULL,
 248 };
 249
 250 static void nvmem_release(struct device *dev)
 251 {
 252         struct nvmem_device *nvmem = to_nvmem_device(dev);
 253
 254         ida_simple_remove(&nvmem_ida, nvmem->id);
 255         kfree(nvmem);
 256 }
 257
 258 static const struct device_type nvmem_provider_type = {
 259         .release        = nvmem_release,
 260 };
 261
 262 static struct bus_type nvmem_bus_type = {
 263         .name           = "nvmem",
 264 };
 265
 266 static int of_nvmem_match(struct device *dev, void *nvmem_np)
 267 {
 268         return dev->of_node == nvmem_np;
 269 }
 270
 271 static struct nvmem_device *of_nvmem_find(struct device_node *nvmem_np)
 272 {
 273         struct device *d;
 274
 275         if (!nvmem_np)
 276                 return NULL;
 277
 278         d = bus_find_device(&nvmem_bus_type, NULL, nvmem_np, of_nvmem_match);
 279
 280         if (!d)
 281                 return NULL;
 282
 283         return to_nvmem_device(d);
 284 }
 285
 286 static struct nvmem_cell *nvmem_find_cell(const char *cell_id)
 287 {
 288         struct nvmem_cell *p;
 289
 290         list_for_each_entry(p, &nvmem_cells, node)
 291                 if (p && !strcmp(p->name, cell_id))
 292                         return p;
 293
 294         return NULL;
 295 }
 296
 297 static void nvmem_cell_drop(struct nvmem_cell *cell)
 298 {
 299         mutex_lock(&nvmem_cells_mutex);
 300         list_del(&cell->node);
 301         mutex_unlock(&nvmem_cells_mutex);
 302         kfree(cell);
 303 }
 304
 305 static void nvmem_device_remove_all_cells(const struct nvmem_device *nvmem)
 306 {
 307         struct nvmem_cell *cell;
 308         struct list_head *p, *n;
 309
 310         list_for_each_safe(p, n, &nvmem_cells) {
 311                 cell = list_entry(p, struct nvmem_cell, node);
 312                 if (cell->nvmem == nvmem)
 313                         nvmem_cell_drop(cell);
 314         }
 315 }
 316
 317 static void nvmem_cell_add(struct nvmem_cell *cell)
 318 {
 319         mutex_lock(&nvmem_cells_mutex);
 320         list_add_tail(&cell->node, &nvmem_cells);
 321         mutex_unlock(&nvmem_cells_mutex);
 322 }
 323
 324 static int nvmem_cell_info_to_nvmem_cell(struct nvmem_device *nvmem,
 325                                    const struct nvmem_cell_info *info,
 326                                    struct nvmem_cell *cell)
 327 {
 328         cell->nvmem = nvmem;
 329         cell->offset = info->offset;
 330         cell->bytes = info->bytes;
 331         cell->name = info->name;
 332
 333         cell->bit_offset = info->bit_offset;
 334         cell->nbits = info->nbits;
 335
 336         if (cell->nbits)
 337                 cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
 338                                            BITS_PER_BYTE);
 339
 340         if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
 341                 dev_err(&nvmem->dev,
 342                         "cell %s unaligned to nvmem stride %d\n",
 343                         cell->name, nvmem->stride);
 344                 return -EINVAL;
 345         }
 346
 347         return 0;
 348 }
 349
 350 static int nvmem_add_cells(struct nvmem_device *nvmem,
 351                            const struct nvmem_config *cfg)
 352 {
 353         struct nvmem_cell **cells;
 354         const struct nvmem_cell_info *info = cfg->cells;
 355         int i, rval;
 356
 357         cells = kcalloc(cfg->ncells, sizeof(*cells), GFP_KERNEL);
 358         if (!cells)
 359                 return -ENOMEM;
 360
 361         for (i = 0; i < cfg->ncells; i++) {
 362                 cells[i] = kzalloc(sizeof(**cells), GFP_KERNEL);
 363                 if (!cells[i]) {
 364                         rval = -ENOMEM;
 365                         goto err;
 366                 }
 367
 368                 rval = nvmem_cell_info_to_nvmem_cell(nvmem, &info[i], cells[i]);
 369                 if (rval) {
 370                         kfree(cells[i]);
 371                         goto err;
 372                 }
 373
 374                 nvmem_cell_add(cells[i]);
 375         }
 376
 377         nvmem->ncells = cfg->ncells;
 378         /* remove tmp array */
 379         kfree(cells);
 380
 381         return 0;
 382 err:
 383         while (i--)
 384                 nvmem_cell_drop(cells[i]);
 385
 386         kfree(cells);
 387
 388         return rval;
 389 }
 390
 391 /*
 392  * nvmem_setup_compat() - Create an additional binary entry in
 393  * drivers sys directory, to be backwards compatible with the older
 394  * drivers/misc/eeprom drivers.
 395  */
 396 static int nvmem_setup_compat(struct nvmem_device *nvmem,
 397                               const struct nvmem_config *config)
 398 {
 399         int rval;
 400
 401         if (!config->base_dev)
 402                 return -EINVAL;
 403
 404         if (nvmem->read_only)
 405                 nvmem->eeprom = bin_attr_ro_root_nvmem;
 406         else
 407                 nvmem->eeprom = bin_attr_rw_root_nvmem;
 408         nvmem->eeprom.attr.name = "eeprom";
 409         nvmem->eeprom.size = nvmem->size;
 410 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 411         nvmem->eeprom.attr.key = &eeprom_lock_key;
 412 #endif
 413         nvmem->eeprom.private = &nvmem->dev;
 414         nvmem->base_dev = config->base_dev;
 415
 416         rval = device_create_bin_file(nvmem->base_dev, &nvmem->eeprom);
 417         if (rval) {
 418                 dev_err(&nvmem->dev,
 419                         "Failed to create eeprom binary file %d\n", rval);
 420                 return rval;
 421         }
 422
 423         nvmem->flags |= FLAG_COMPAT;
 424
 425         return 0;
 426 }
 427
 428 /**
 429  * nvmem_register() - Register a nvmem device for given nvmem_config.
 430  * Also creates an binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
 431  *
 432  * @config: nvmem device configuration with which nvmem device is created.
 433  *
 434  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
 435  * on success.
 436  */
 437
 438 struct nvmem_device *nvmem_register(const struct nvmem_config *config)
 439 {
 440         struct nvmem_device *nvmem;
 441         struct device_node *np;
 442         int rval;
 443
 444         if (!config->dev)
 445                 return ERR_PTR(-EINVAL);
 446
 447         nvmem = kzalloc(sizeof(*nvmem), GFP_KERNEL);
 448         if (!nvmem)
 449                 return ERR_PTR(-ENOMEM);
 450
 451         rval  = ida_simple_get(&nvmem_ida, 0, 0, GFP_KERNEL);
 452         if (rval < 0) {
 453                 kfree(nvmem);
 454                 return ERR_PTR(rval);
 455         }
 456
 457         nvmem->id = rval;
 458         nvmem->owner = config->owner;
 459         nvmem->stride = config->stride;
 460         nvmem->word_size = config->word_size;
 461         nvmem->size = config->size;
 462         nvmem->dev.type = &nvmem_provider_type;
 463         nvmem->dev.bus = &nvmem_bus_type;
 464         nvmem->dev.parent = config->dev;
 465         nvmem->priv = config->priv;
 466         nvmem->reg_read = config->reg_read;
 467         nvmem->reg_write = config->reg_write;
 468         np = config->dev->of_node;
 469         nvmem->dev.of_node = np;
 470         dev_set_name(&nvmem->dev, "%s%d",
 471                      config->name ? : "nvmem", config->id);
 472
 473         nvmem->read_only = of_property_read_bool(np, "read-only") |
 474                            config->read_only;
 475
 476         if (config->root_only)
 477                 nvmem->dev.groups = nvmem->read_only ?
 478                         nvmem_ro_root_dev_groups :
 479                         nvmem_rw_root_dev_groups;
 480         else
 481                 nvmem->dev.groups = nvmem->read_only ?
 482                         nvmem_ro_dev_groups :
 483                         nvmem_rw_dev_groups;
 484
 485         device_initialize(&nvmem->dev);
 486
 487         dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
 488
 489         rval = device_add(&nvmem->dev);
 490         if (rval)
 491                 goto out;
 492
 493         if (config->compat) {
 494                 rval = nvmem_setup_compat(nvmem, config);
 495                 if (rval)
 496                         goto out;
 497         }
 498
 499         if (config->cells)
 500                 nvmem_add_cells(nvmem, config);
 501
 502         return nvmem;
 503 out:
 504         ida_simple_remove(&nvmem_ida, nvmem->id);
 505         kfree(nvmem);
 506         return ERR_PTR(rval);
 507 }
 508 EXPORT_SYMBOL_GPL(nvmem_register);
 509
 510 /**
 511  * nvmem_unregister() - Unregister previously registered nvmem device
 512  *
 513  * @nvmem: Pointer to previously registered nvmem device.
 514  *
 515  * Return: Will be an negative on error or a zero on success.
 516  */
 517 int nvmem_unregister(struct nvmem_device *nvmem)
 518 {
 519         mutex_lock(&nvmem_mutex);
 520         if (nvmem->users) {
 521                 mutex_unlock(&nvmem_mutex);
 522                 return -EBUSY;
 523         }
 524         mutex_unlock(&nvmem_mutex);
 525
 526         if (nvmem->flags & FLAG_COMPAT)
 527                 device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
 528
 529         nvmem_device_remove_all_cells(nvmem);
 530         device_del(&nvmem->dev);
 531
 532         return 0;
 533 }
 534 EXPORT_SYMBOL_GPL(nvmem_unregister);
 535
 536 static struct nvmem_device *__nvmem_device_get(struct device_node *np,
 537                                                struct nvmem_cell **cellp,
 538                                                const char *cell_id)
 539 {
 540         struct nvmem_device *nvmem = NULL;
 541
 542         mutex_lock(&nvmem_mutex);
 543
 544         if (np) {
 545                 nvmem = of_nvmem_find(np);
 546                 if (!nvmem) {
 547                         mutex_unlock(&nvmem_mutex);
 548                         return ERR_PTR(-EPROBE_DEFER);
 549                 }
 550         } else {
 551                 struct nvmem_cell *cell = nvmem_find_cell(cell_id);
 552
 553                 if (cell) {
 554                         nvmem = cell->nvmem;
 555                         *cellp = cell;
 556                 }
 557
 558                 if (!nvmem) {
 559                         mutex_unlock(&nvmem_mutex);
 560                         return ERR_PTR(-ENOENT);
 561                 }
 562         }
 563
 564         nvmem->users++;
 565         mutex_unlock(&nvmem_mutex);
 566
 567         if (!try_module_get(nvmem->owner)) {
 568                 dev_err(&nvmem->dev,
 569                         "could not increase module refcount for cell %s\n",
 570                         nvmem->name);
 571
 572                 mutex_lock(&nvmem_mutex);
 573                 nvmem->users--;
 574                 mutex_unlock(&nvmem_mutex);
 575
 576                 return ERR_PTR(-EINVAL);
 577         }
 578
 579         return nvmem;
 580 }
 581
 582 static void __nvmem_device_put(struct nvmem_device *nvmem)
 583 {
 584         module_put(nvmem->owner);
 585         mutex_lock(&nvmem_mutex);
 586         nvmem->users--;
 587         mutex_unlock(&nvmem_mutex);
 588 }
 589
 590 static int nvmem_match(struct device *dev, void *data)
 591 {
 592         return !strcmp(dev_name(dev), data);
 593 }
 594
 595 static struct nvmem_device *nvmem_find(const char *name)
 596 {
 597         struct device *d;
 598
 599         d = bus_find_device(&nvmem_bus_type, NULL, (void *)name, nvmem_match);
 600
 601         if (!d)
 602                 return NULL;
 603
 604         return to_nvmem_device(d);
 605 }
 606
 607 #if IS_ENABLED(CONFIG_NVMEM) && IS_ENABLED(CONFIG_OF)
 608 /**
 609  * of_nvmem_device_get() - Get nvmem device from a given id
 610  *
 611  * @np: Device tree node that uses the nvmem device.
 612  * @id: nvmem name from nvmem-names property.
 613  *
 614  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
 615  * on success.
 616  */
 617 struct nvmem_device *of_nvmem_device_get(struct device_node *np, const char *id)
 618 {
 619
 620         struct device_node *nvmem_np;
 621         int index;
 622
 623         index = of_property_match_string(np, "nvmem-names", id);
 624
 625         nvmem_np = of_parse_phandle(np, "nvmem", index);
 626         if (!nvmem_np)
 627                 return ERR_PTR(-EINVAL);
 628
 629         return __nvmem_device_get(nvmem_np, NULL, NULL);
 630 }
 631 EXPORT_SYMBOL_GPL(of_nvmem_device_get);
 632 #endif
 633
 634 /**
 635  * nvmem_device_get() - Get nvmem device from a given id
 636  *
 637  * @dev: Device that uses the nvmem device.
 638  * @dev_name: name of the requested nvmem device.
 639  *
 640  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
 641  * on success.
 642  */
 643 struct nvmem_device *nvmem_device_get(struct device *dev, const char *dev_name)
 644 {
 645         if (dev->of_node) { /* try dt first */
 646                 struct nvmem_device *nvmem;
 647
 648                 nvmem = of_nvmem_device_get(dev->of_node, dev_name);
 649
 650                 if (!IS_ERR(nvmem) || PTR_ERR(nvmem) == -EPROBE_DEFER)
 651                         return nvmem;
 652
 653         }
 654
 655         return nvmem_find(dev_name);
 656 }
 657 EXPORT_SYMBOL_GPL(nvmem_device_get);
 658
 659 static int devm_nvmem_device_match(struct device *dev, void *res, void *data)
 660 {
 661         struct nvmem_device **nvmem = res;
 662
 663         if (WARN_ON(!nvmem || !*nvmem))
 664                 return 0;
 665
 666         return *nvmem == data;
 667 }
 668
 669 static void devm_nvmem_device_release(struct device *dev, void *res)
 670 {
 671         nvmem_device_put(*(struct nvmem_device **)res);
 672 }
 673
 674 /**
 675  * devm_nvmem_device_put() - put alredy got nvmem device
 676  *
 677  * @dev: Device that uses the nvmem device.
 678  * @nvmem: pointer to nvmem device allocated by devm_nvmem_cell_get(),
 679  * that needs to be released.
 680  */
 681 void devm_nvmem_device_put(struct device *dev, struct nvmem_device *nvmem)
 682 {
 683         int ret;
 684
 685         ret = devres_release(dev, devm_nvmem_device_release,
 686                              devm_nvmem_device_match, nvmem);
 687
 688         WARN_ON(ret);
 689 }
 690 EXPORT_SYMBOL_GPL(devm_nvmem_device_put);
 691
 692 /**
 693  * nvmem_device_put() - put alredy got nvmem device
 694  *
 695  * @nvmem: pointer to nvmem device that needs to be released.
 696  */
 697 void nvmem_device_put(struct nvmem_device *nvmem)
 698 {
 699         __nvmem_device_put(nvmem);
 700 }
 701 EXPORT_SYMBOL_GPL(nvmem_device_put);
 702
 703 /**
 704  * devm_nvmem_device_get() - Get nvmem cell of device form a given id
 705  *
 706  * @dev: Device that requests the nvmem device.
 707  * @id: name id for the requested nvmem device.
 708  *
 709  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_cell
 710  * on success.  The nvmem_cell will be freed by the automatically once the
 711  * device is freed.
 712  */
 713 struct nvmem_device *devm_nvmem_device_get(struct device *dev, const char *id)
 714 {
 715         struct nvmem_device **ptr, *nvmem;
 716
 717         ptr = devres_alloc(devm_nvmem_device_release, sizeof(*ptr), GFP_KERNEL);
 718         if (!ptr)
 719                 return ERR_PTR(-ENOMEM);
 720
 721         nvmem = nvmem_device_get(dev, id);
 722         if (!IS_ERR(nvmem)) {
 723                 *ptr = nvmem;
 724                 devres_add(dev, ptr);
 725         } else {
 726                 devres_free(ptr);
 727         }
 728
 729         return nvmem;
 730 }
 731 EXPORT_SYMBOL_GPL(devm_nvmem_device_get);
 732
 733 static struct nvmem_cell *nvmem_cell_get_from_list(const char *cell_id)
 734 {
 735         struct nvmem_cell *cell = NULL;
 736         struct nvmem_device *nvmem;
 737
 738         nvmem = __nvmem_device_get(NULL, &cell, cell_id);
 739         if (IS_ERR(nvmem))
 740                 return ERR_CAST(nvmem);
 741
 742         return cell;
 743 }
 744
 745 #if IS_ENABLED(CONFIG_NVMEM) && IS_ENABLED(CONFIG_OF)
 746 /**
 747  * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
 748  *
 749  * @np: Device tree node that uses the nvmem cell.
 750  * @name: nvmem cell name from nvmem-cell-names property, or NULL
 751  *        for the cell at index 0 (the lone cell with no accompanying
 752  *        nvmem-cell-names property).
 753  *
 754  * Return: Will be an ERR_PTR() on error or a valid pointer
 755  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
 756  * nvmem_cell_put().
 757  */
 758 struct nvmem_cell *of_nvmem_cell_get(struct device_node *np,
 759                                             const char *name)
 760 {
 761         struct device_node *cell_np, *nvmem_np;
 762         struct nvmem_cell *cell;
 763         struct nvmem_device *nvmem;
 764         const __be32 *addr;
 765         int rval, len;
 766         int index = 0;
 767
 768         /* if cell name exists, find index to the name */
 769         if (name)
 770                 index = of_property_match_string(np, "nvmem-cell-names", name);
 771
 772         cell_np = of_parse_phandle(np, "nvmem-cells", index);
 773         if (!cell_np)
 774                 return ERR_PTR(-EINVAL);
 775
 776         nvmem_np = of_get_next_parent(cell_np);
 777         if (!nvmem_np)
 778                 return ERR_PTR(-EINVAL);
 779
 780         nvmem = __nvmem_device_get(nvmem_np, NULL, NULL);
 781         if (IS_ERR(nvmem))
 782                 return ERR_CAST(nvmem);
 783
 784         addr = of_get_property(cell_np, "reg", &len);
 785         if (!addr || (len < 2 * sizeof(u32))) {
 786                 dev_err(&nvmem->dev, "nvmem: invalid reg on %s\n",
 787                         cell_np->full_name);
 788                 rval  = -EINVAL;
 789                 goto err_mem;
 790         }
 791
 792         cell = kzalloc(sizeof(*cell), GFP_KERNEL);
 793         if (!cell) {
 794                 rval = -ENOMEM;
 795                 goto err_mem;
 796         }
 797
 798         cell->nvmem = nvmem;
 799         cell->offset = be32_to_cpup(addr++);
 800         cell->bytes = be32_to_cpup(addr);
 801         cell->name = cell_np->name;
 802
 803         addr = of_get_property(cell_np, "bits", &len);
 804         if (addr && len == (2 * sizeof(u32))) {
 805                 cell->bit_offset = be32_to_cpup(addr++);
 806                 cell->nbits = be32_to_cpup(addr);
 807         }
 808
 809         if (cell->nbits)
 810                 cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
 811                                            BITS_PER_BYTE);
 812
 813         if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
 814                         dev_err(&nvmem->dev,
 815                                 "cell %s unaligned to nvmem stride %d\n",
 816                                 cell->name, nvmem->stride);
 817                 rval  = -EINVAL;
 818                 goto err_sanity;
 819         }
 820
 821         nvmem_cell_add(cell);
 822
 823         return cell;
 824
 825 err_sanity:
 826         kfree(cell);
 827
 828 err_mem:
 829         __nvmem_device_put(nvmem);
 830
 831         return ERR_PTR(rval);
 832 }
 833 EXPORT_SYMBOL_GPL(of_nvmem_cell_get);
 834 #endif
 835
 836 /**
 837  * nvmem_cell_get() - Get nvmem cell of device form a given cell name
 838  *
 839  * @dev: Device that requests the nvmem cell.
 840  * @cell_id: nvmem cell name to get.
 841  *
 842  * Return: Will be an ERR_PTR() on error or a valid pointer
 843  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
 844  * nvmem_cell_put().
 845  */
 846 struct nvmem_cell *nvmem_cell_get(struct device *dev, const char *cell_id)
 847 {
 848         struct nvmem_cell *cell;
 849
 850         if (dev->of_node) { /* try dt first */
 851                 cell = of_nvmem_cell_get(dev->of_node, cell_id);
 852                 if (!IS_ERR(cell) || PTR_ERR(cell) == -EPROBE_DEFER)
 853                         return cell;
 854         }
 855
 856         return nvmem_cell_get_from_list(cell_id);
 857 }
 858 EXPORT_SYMBOL_GPL(nvmem_cell_get);
 859
 860 static void devm_nvmem_cell_release(struct device *dev, void *res)
 861 {
 862         nvmem_cell_put(*(struct nvmem_cell **)res);
 863 }
 864
 865 /**
 866  * devm_nvmem_cell_get() - Get nvmem cell of device form a given id
 867  *
 868  * @dev: Device that requests the nvmem cell.
 869  * @id: nvmem cell name id to get.
 870  *
 871  * Return: Will be an ERR_PTR() on error or a valid pointer
 872  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
 873  * automatically once the device is freed.
 874  */
 875 struct nvmem_cell *devm_nvmem_cell_get(struct device *dev, const char *id)
 876 {
 877         struct nvmem_cell **ptr, *cell;
 878
 879         ptr = devres_alloc(devm_nvmem_cell_release, sizeof(*ptr), GFP_KERNEL);
 880         if (!ptr)
 881                 return ERR_PTR(-ENOMEM);
 882
 883         cell = nvmem_cell_get(dev, id);
 884         if (!IS_ERR(cell)) {
 885                 *ptr = cell;
 886                 devres_add(dev, ptr);
 887         } else {
 888                 devres_free(ptr);
 889         }
 890
 891         return cell;
 892 }
 893 EXPORT_SYMBOL_GPL(devm_nvmem_cell_get);
 894
 895 static int devm_nvmem_cell_match(struct device *dev, void *res, void *data)
 896 {
 897         struct nvmem_cell **c = res;
 898
 899         if (WARN_ON(!c || !*c))
 900                 return 0;
 901
 902         return *c == data;
 903 }
 904
 905 /**
 906  * devm_nvmem_cell_put() - Release previously allocated nvmem cell
 907  * from devm_nvmem_cell_get.
 908  *
 909  * @dev: Device that requests the nvmem cell.
 910  * @cell: Previously allocated nvmem cell by devm_nvmem_cell_get().
 911  */
 912 void devm_nvmem_cell_put(struct device *dev, struct nvmem_cell *cell)
 913 {
 914         int ret;
 915
 916         ret = devres_release(dev, devm_nvmem_cell_release,
 917                                 devm_nvmem_cell_match, cell);
 918
 919         WARN_ON(ret);
 920 }
 921 EXPORT_SYMBOL(devm_nvmem_cell_put);
 922
 923 /**
 924  * nvmem_cell_put() - Release previously allocated nvmem cell.
 925  *
 926  * @cell: Previously allocated nvmem cell by nvmem_cell_get().
 927  */
 928 void nvmem_cell_put(struct nvmem_cell *cell)
 929 {
 930         struct nvmem_device *nvmem = cell->nvmem;
 931
 932         __nvmem_device_put(nvmem);
 933         nvmem_cell_drop(cell);
 934 }
 935 EXPORT_SYMBOL_GPL(nvmem_cell_put);
 936
 937 static inline void nvmem_shift_read_buffer_in_place(struct nvmem_cell *cell,
 938                                                     void *buf)
 939 {
 940         u8 *p, *b;
 941         int i, bit_offset = cell->bit_offset;
 942
 943         p = b = buf;
 944         if (bit_offset) {
 945                 /* First shift */
 946                 *b++ >>= bit_offset;
 947
 948                 /* setup rest of the bytes if any */
 949                 for (i = 1; i < cell->bytes; i++) {
 950                         /* Get bits from next byte and shift them towards msb */
 951                         *p |= *b << (BITS_PER_BYTE - bit_offset);
 952
 953                         p = b;
 954                         *b++ >>= bit_offset;
 955                 }
 956
 957                 /* result fits in less bytes */
 958                 if (cell->bytes != DIV_ROUND_UP(cell->nbits, BITS_PER_BYTE))
 959                         *p-- = 0;
 960         }
 961         /* clear msb bits if any leftover in the last byte */
 962         *p &= GENMASK((cell->nbits%BITS_PER_BYTE) - 1, 0);
 963 }
 964
 965 static int __nvmem_cell_read(struct nvmem_device *nvmem,
 966                       struct nvmem_cell *cell,
 967                       void *buf, size_t *len)
 968 {
 969         int rc;
 970
 971         rc = nvmem_reg_read(nvmem, cell->offset, buf, cell->bytes);
 972
 973         if (rc)
 974                 return rc;
 975
 976         /* shift bits in-place */
 977         if (cell->bit_offset || cell->nbits)
 978                 nvmem_shift_read_buffer_in_place(cell, buf);
 979
 980         if (len)
 981                 *len = cell->bytes;
 982
 983         return 0;
 984 }
 985
 986 /**
 987  * nvmem_cell_read() - Read a given nvmem cell
 988  *
 989  * @cell: nvmem cell to be read.
 990  * @len: pointer to length of cell which will be populated on successful read;
 991  *       can be NULL.
 992  *
 993  * Return: ERR_PTR() on error or a valid pointer to a buffer on success. The
 994  * buffer should be freed by the consumer with a kfree().
 995  */
 996 void *nvmem_cell_read(struct nvmem_cell *cell, size_t *len)
 997 {
 998         struct nvmem_device *nvmem = cell->nvmem;
 999         u8 *buf;
1000         int rc;
1001
1002         if (!nvmem)
1003                 return ERR_PTR(-EINVAL);
1004
1005         buf = kzalloc(cell->bytes, GFP_KERNEL);
1006         if (!buf)
1007                 return ERR_PTR(-ENOMEM);
1008
1009         rc = __nvmem_cell_read(nvmem, cell, buf, len);
1010         if (rc) {
1011                 kfree(buf);
1012                 return ERR_PTR(rc);
1013         }
1014
1015         return buf;
1016 }
1017 EXPORT_SYMBOL_GPL(nvmem_cell_read);
1018
1019 static inline void *nvmem_cell_prepare_write_buffer(struct nvmem_cell *cell,
1020                                                     u8 *_buf, int len)
1021 {
1022         struct nvmem_device *nvmem = cell->nvmem;
1023         int i, rc, nbits, bit_offset = cell->bit_offset;
1024         u8 v, *p, *buf, *b, pbyte, pbits;
1025
1026         nbits = cell->nbits;
1027         buf = kzalloc(cell->bytes, GFP_KERNEL);
1028         if (!buf)
1029                 return ERR_PTR(-ENOMEM);
1030
1031         memcpy(buf, _buf, len);
1032         p = b = buf;
1033
1034         if (bit_offset) {
1035                 pbyte = *b;
1036                 *b <<= bit_offset;
1037
1038                 /* setup the first byte with lsb bits from nvmem */
1039                 rc = nvmem_reg_read(nvmem, cell->offset, &v, 1);
1040                 *b++ |= GENMASK(bit_offset - 1, 0) & v;
1041
1042                 /* setup rest of the byte if any */
1043                 for (i = 1; i < cell->bytes; i++) {
1044                         /* Get last byte bits and shift them towards lsb */
1045                         pbits = pbyte >> (BITS_PER_BYTE - 1 - bit_offset);
1046                         pbyte = *b;
1047                         p = b;
1048                         *b <<= bit_offset;
1049                         *b++ |= pbits;
1050                 }
1051         }
1052
1053         /* if it's not end on byte boundary */
1054         if ((nbits + bit_offset) % BITS_PER_BYTE) {
1055                 /* setup the last byte with msb bits from nvmem */
1056                 rc = nvmem_reg_read(nvmem,
1057                                     cell->offset + cell->bytes - 1, &v, 1);
1058                 *p |= GENMASK(7, (nbits + bit_offset) % BITS_PER_BYTE) & v;
1059
1060         }
1061
1062         return buf;
1063 }
1064
1065 /**
1066  * nvmem_cell_write() - Write to a given nvmem cell
1067  *
1068  * @cell: nvmem cell to be written.
1069  * @buf: Buffer to be written.
1070  * @len: length of buffer to be written to nvmem cell.
1071  *
1072  * Return: length of bytes written or negative on failure.
1073  */
1074 int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len)
1075 {
1076         struct nvmem_device *nvmem = cell->nvmem;
1077         int rc;
1078
1079         if (!nvmem || nvmem->read_only ||
1080             (cell->bit_offset == 0 && len != cell->bytes))
1081                 return -EINVAL;
1082
1083         if (cell->bit_offset || cell->nbits) {
1084                 buf = nvmem_cell_prepare_write_buffer(cell, buf, len);
1085                 if (IS_ERR(buf))
1086                         return PTR_ERR(buf);
1087         }
1088
1089         rc = nvmem_reg_write(nvmem, cell->offset, buf, cell->bytes);
1090
1091         /* free the tmp buffer */
1092         if (cell->bit_offset || cell->nbits)
1093                 kfree(buf);
1094
1095         if (rc)
1096                 return rc;
1097
1098         return len;
1099 }
1100 EXPORT_SYMBOL_GPL(nvmem_cell_write);
1101
1102 /**
1103  * nvmem_device_cell_read() - Read a given nvmem device and cell
1104  *
1105  * @nvmem: nvmem device to read from.
1106  * @info: nvmem cell info to be read.
1107  * @buf: buffer pointer which will be populated on successful read.
1108  *
1109  * Return: length of successful bytes read on success and negative
1110  * error code on error.
1111  */
1112 ssize_t nvmem_device_cell_read(struct nvmem_device *nvmem,
1113                            struct nvmem_cell_info *info, void *buf)
1114 {
1115         struct nvmem_cell cell;
1116         int rc;
1117         ssize_t len;
1118
1119         if (!nvmem)
1120                 return -EINVAL;
1121
1122         rc = nvmem_cell_info_to_nvmem_cell(nvmem, info, &cell);
1123         if (rc)
1124                 return rc;
1125
1126         rc = __nvmem_cell_read(nvmem, &cell, buf, &len);
1127         if (rc)
1128                 return rc;
1129
1130         return len;
1131 }
1132 EXPORT_SYMBOL_GPL(nvmem_device_cell_read);
1133
1134 /**
1135  * nvmem_device_cell_write() - Write cell to a given nvmem device
1136  *
1137  * @nvmem: nvmem device to be written to.
1138  * @info: nvmem cell info to be written.
1139  * @buf: buffer to be written to cell.
1140  *
1141  * Return: length of bytes written or negative error code on failure.
1142  * */
1143 int nvmem_device_cell_write(struct nvmem_device *nvmem,
1144                             struct nvmem_cell_info *info, void *buf)
1145 {
1146         struct nvmem_cell cell;
1147         int rc;
1148
1149         if (!nvmem)
1150                 return -EINVAL;
1151
1152         rc = nvmem_cell_info_to_nvmem_cell(nvmem, info, &cell);
1153         if (rc)
1154                 return rc;
1155
1156         return nvmem_cell_write(&cell, buf, cell.bytes);
1157 }
1158 EXPORT_SYMBOL_GPL(nvmem_device_cell_write);
1159
1160 /**
1161  * nvmem_device_read() - Read from a given nvmem device
1162  *
1163  * @nvmem: nvmem device to read from.
1164  * @offset: offset in nvmem device.
1165  * @bytes: number of bytes to read.
1166  * @buf: buffer pointer which will be populated on successful read.
1167  *
1168  * Return: length of successful bytes read on success and negative
1169  * error code on error.
1170  */
1171 int nvmem_device_read(struct nvmem_device *nvmem,
1172                       unsigned int offset,
1173                       size_t bytes, void *buf)
1174 {
1175         int rc;
1176
1177         if (!nvmem)
1178                 return -EINVAL;
1179
1180         rc = nvmem_reg_read(nvmem, offset, buf, bytes);
1181
1182         if (rc)
1183                 return rc;
1184
1185         return bytes;
1186 }
1187 EXPORT_SYMBOL_GPL(nvmem_device_read);
1188
1189 /**
1190  * nvmem_device_write() - Write cell to a given nvmem device
1191  *
1192  * @nvmem: nvmem device to be written to.
1193  * @offset: offset in nvmem device.
1194  * @bytes: number of bytes to write.
1195  * @buf: buffer to be written.
1196  *
1197  * Return: length of bytes written or negative error code on failure.
1198  * */
1199 int nvmem_device_write(struct nvmem_device *nvmem,
1200                        unsigned int offset,
1201                        size_t bytes, void *buf)
1202 {
1203         int rc;
1204
1205         if (!nvmem)
1206                 return -EINVAL;
1207
1208         rc = nvmem_reg_write(nvmem, offset, buf, bytes);
1209
1210         if (rc)
1211                 return rc;
1212
1213
1214         return bytes;
1215 }
1216 EXPORT_SYMBOL_GPL(nvmem_device_write);
1217
1218 static int __init nvmem_init(void)
1219 {
1220         return bus_register(&nvmem_bus_type);
1221 }
1222
1223 static void __exit nvmem_exit(void)
1224 {
1225         bus_unregister(&nvmem_bus_type);
1226 }
1227
1228 subsys_initcall(nvmem_init);
1229 module_exit(nvmem_exit);
1230
1231 MODULE_AUTHOR("Srinivas Kandagatla <srinivas.kandagatla@linaro.org");
1232 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com");
1233 MODULE_DESCRIPTION("nvmem Driver Core");
1234 MODULE_LICENSE("GPL v2");