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  * @dev node: 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  * @id: nvmem name from nvmem-names property.
 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  * @nvmem: pointer to nvmem device allocated by devm_nvmem_cell_get(),
 678  * that needs to be released.
 679  */
 680 void devm_nvmem_device_put(struct device *dev, struct nvmem_device *nvmem)
 681 {
 682         int ret;
 683
 684         ret = devres_release(dev, devm_nvmem_device_release,
 685                              devm_nvmem_device_match, nvmem);
 686
 687         WARN_ON(ret);
 688 }
 689 EXPORT_SYMBOL_GPL(devm_nvmem_device_put);
 690
 691 /**
 692  * nvmem_device_put() - put alredy got nvmem device
 693  *
 694  * @nvmem: pointer to nvmem device that needs to be released.
 695  */
 696 void nvmem_device_put(struct nvmem_device *nvmem)
 697 {
 698         __nvmem_device_put(nvmem);
 699 }
 700 EXPORT_SYMBOL_GPL(nvmem_device_put);
 701
 702 /**
 703  * devm_nvmem_device_get() - Get nvmem cell of device form a given id
 704  *
 705  * @dev node: Device tree node that uses the nvmem cell
 706  * @id: nvmem name in nvmems property.
 707  *
 708  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_cell
 709  * on success.  The nvmem_cell will be freed by the automatically once the
 710  * device is freed.
 711  */
 712 struct nvmem_device *devm_nvmem_device_get(struct device *dev, const char *id)
 713 {
 714         struct nvmem_device **ptr, *nvmem;
 715
 716         ptr = devres_alloc(devm_nvmem_device_release, sizeof(*ptr), GFP_KERNEL);
 717         if (!ptr)
 718                 return ERR_PTR(-ENOMEM);
 719
 720         nvmem = nvmem_device_get(dev, id);
 721         if (!IS_ERR(nvmem)) {
 722                 *ptr = nvmem;
 723                 devres_add(dev, ptr);
 724         } else {
 725                 devres_free(ptr);
 726         }
 727
 728         return nvmem;
 729 }
 730 EXPORT_SYMBOL_GPL(devm_nvmem_device_get);
 731
 732 static struct nvmem_cell *nvmem_cell_get_from_list(const char *cell_id)
 733 {
 734         struct nvmem_cell *cell = NULL;
 735         struct nvmem_device *nvmem;
 736
 737         nvmem = __nvmem_device_get(NULL, &cell, cell_id);
 738         if (IS_ERR(nvmem))
 739                 return ERR_CAST(nvmem);
 740
 741         return cell;
 742 }
 743
 744 #if IS_ENABLED(CONFIG_NVMEM) && IS_ENABLED(CONFIG_OF)
 745 /**
 746  * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
 747  *
 748  * @dev node: Device tree node that uses the nvmem cell
 749  * @id: nvmem cell name from nvmem-cell-names property.
 750  *
 751  * Return: Will be an ERR_PTR() on error or a valid pointer
 752  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
 753  * nvmem_cell_put().
 754  */
 755 struct nvmem_cell *of_nvmem_cell_get(struct device_node *np,
 756                                             const char *name)
 757 {
 758         struct device_node *cell_np, *nvmem_np;
 759         struct nvmem_cell *cell;
 760         struct nvmem_device *nvmem;
 761         const __be32 *addr;
 762         int rval, len, index;
 763
 764         index = of_property_match_string(np, "nvmem-cell-names", name);
 765
 766         cell_np = of_parse_phandle(np, "nvmem-cells", index);
 767         if (!cell_np)
 768                 return ERR_PTR(-EINVAL);
 769
 770         nvmem_np = of_get_next_parent(cell_np);
 771         if (!nvmem_np)
 772                 return ERR_PTR(-EINVAL);
 773
 774         nvmem = __nvmem_device_get(nvmem_np, NULL, NULL);
 775         if (IS_ERR(nvmem))
 776                 return ERR_CAST(nvmem);
 777
 778         addr = of_get_property(cell_np, "reg", &len);
 779         if (!addr || (len < 2 * sizeof(u32))) {
 780                 dev_err(&nvmem->dev, "nvmem: invalid reg on %s\n",
 781                         cell_np->full_name);
 782                 rval  = -EINVAL;
 783                 goto err_mem;
 784         }
 785
 786         cell = kzalloc(sizeof(*cell), GFP_KERNEL);
 787         if (!cell) {
 788                 rval = -ENOMEM;
 789                 goto err_mem;
 790         }
 791
 792         cell->nvmem = nvmem;
 793         cell->offset = be32_to_cpup(addr++);
 794         cell->bytes = be32_to_cpup(addr);
 795         cell->name = cell_np->name;
 796
 797         addr = of_get_property(cell_np, "bits", &len);
 798         if (addr && len == (2 * sizeof(u32))) {
 799                 cell->bit_offset = be32_to_cpup(addr++);
 800                 cell->nbits = be32_to_cpup(addr);
 801         }
 802
 803         if (cell->nbits)
 804                 cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
 805                                            BITS_PER_BYTE);
 806
 807         if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
 808                         dev_err(&nvmem->dev,
 809                                 "cell %s unaligned to nvmem stride %d\n",
 810                                 cell->name, nvmem->stride);
 811                 rval  = -EINVAL;
 812                 goto err_sanity;
 813         }
 814
 815         nvmem_cell_add(cell);
 816
 817         return cell;
 818
 819 err_sanity:
 820         kfree(cell);
 821
 822 err_mem:
 823         __nvmem_device_put(nvmem);
 824
 825         return ERR_PTR(rval);
 826 }
 827 EXPORT_SYMBOL_GPL(of_nvmem_cell_get);
 828 #endif
 829
 830 /**
 831  * nvmem_cell_get() - Get nvmem cell of device form a given cell name
 832  *
 833  * @dev node: Device tree node that uses the nvmem cell
 834  * @id: nvmem cell name to get.
 835  *
 836  * Return: Will be an ERR_PTR() on error or a valid pointer
 837  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
 838  * nvmem_cell_put().
 839  */
 840 struct nvmem_cell *nvmem_cell_get(struct device *dev, const char *cell_id)
 841 {
 842         struct nvmem_cell *cell;
 843
 844         if (dev->of_node) { /* try dt first */
 845                 cell = of_nvmem_cell_get(dev->of_node, cell_id);
 846                 if (!IS_ERR(cell) || PTR_ERR(cell) == -EPROBE_DEFER)
 847                         return cell;
 848         }
 849
 850         return nvmem_cell_get_from_list(cell_id);
 851 }
 852 EXPORT_SYMBOL_GPL(nvmem_cell_get);
 853
 854 static void devm_nvmem_cell_release(struct device *dev, void *res)
 855 {
 856         nvmem_cell_put(*(struct nvmem_cell **)res);
 857 }
 858
 859 /**
 860  * devm_nvmem_cell_get() - Get nvmem cell of device form a given id
 861  *
 862  * @dev node: Device tree node that uses the nvmem cell
 863  * @id: nvmem id in nvmem-names property.
 864  *
 865  * Return: Will be an ERR_PTR() on error or a valid pointer
 866  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
 867  * automatically once the device is freed.
 868  */
 869 struct nvmem_cell *devm_nvmem_cell_get(struct device *dev, const char *id)
 870 {
 871         struct nvmem_cell **ptr, *cell;
 872
 873         ptr = devres_alloc(devm_nvmem_cell_release, sizeof(*ptr), GFP_KERNEL);
 874         if (!ptr)
 875                 return ERR_PTR(-ENOMEM);
 876
 877         cell = nvmem_cell_get(dev, id);
 878         if (!IS_ERR(cell)) {
 879                 *ptr = cell;
 880                 devres_add(dev, ptr);
 881         } else {
 882                 devres_free(ptr);
 883         }
 884
 885         return cell;
 886 }
 887 EXPORT_SYMBOL_GPL(devm_nvmem_cell_get);
 888
 889 static int devm_nvmem_cell_match(struct device *dev, void *res, void *data)
 890 {
 891         struct nvmem_cell **c = res;
 892
 893         if (WARN_ON(!c || !*c))
 894                 return 0;
 895
 896         return *c == data;
 897 }
 898
 899 /**
 900  * devm_nvmem_cell_put() - Release previously allocated nvmem cell
 901  * from devm_nvmem_cell_get.
 902  *
 903  * @cell: Previously allocated nvmem cell by devm_nvmem_cell_get()
 904  */
 905 void devm_nvmem_cell_put(struct device *dev, struct nvmem_cell *cell)
 906 {
 907         int ret;
 908
 909         ret = devres_release(dev, devm_nvmem_cell_release,
 910                                 devm_nvmem_cell_match, cell);
 911
 912         WARN_ON(ret);
 913 }
 914 EXPORT_SYMBOL(devm_nvmem_cell_put);
 915
 916 /**
 917  * nvmem_cell_put() - Release previously allocated nvmem cell.
 918  *
 919  * @cell: Previously allocated nvmem cell by nvmem_cell_get()
 920  */
 921 void nvmem_cell_put(struct nvmem_cell *cell)
 922 {
 923         struct nvmem_device *nvmem = cell->nvmem;
 924
 925         __nvmem_device_put(nvmem);
 926         nvmem_cell_drop(cell);
 927 }
 928 EXPORT_SYMBOL_GPL(nvmem_cell_put);
 929
 930 static inline void nvmem_shift_read_buffer_in_place(struct nvmem_cell *cell,
 931                                                     void *buf)
 932 {
 933         u8 *p, *b;
 934         int i, bit_offset = cell->bit_offset;
 935
 936         p = b = buf;
 937         if (bit_offset) {
 938                 /* First shift */
 939                 *b++ >>= bit_offset;
 940
 941                 /* setup rest of the bytes if any */
 942                 for (i = 1; i < cell->bytes; i++) {
 943                         /* Get bits from next byte and shift them towards msb */
 944                         *p |= *b << (BITS_PER_BYTE - bit_offset);
 945
 946                         p = b;
 947                         *b++ >>= bit_offset;
 948                 }
 949
 950                 /* result fits in less bytes */
 951                 if (cell->bytes != DIV_ROUND_UP(cell->nbits, BITS_PER_BYTE))
 952                         *p-- = 0;
 953         }
 954         /* clear msb bits if any leftover in the last byte */
 955         *p &= GENMASK((cell->nbits%BITS_PER_BYTE) - 1, 0);
 956 }
 957
 958 static int __nvmem_cell_read(struct nvmem_device *nvmem,
 959                       struct nvmem_cell *cell,
 960                       void *buf, size_t *len)
 961 {
 962         int rc;
 963
 964         rc = nvmem_reg_read(nvmem, cell->offset, buf, cell->bytes);
 965
 966         if (rc)
 967                 return rc;
 968
 969         /* shift bits in-place */
 970         if (cell->bit_offset || cell->nbits)
 971                 nvmem_shift_read_buffer_in_place(cell, buf);
 972
 973         *len = cell->bytes;
 974
 975         return 0;
 976 }
 977
 978 /**
 979  * nvmem_cell_read() - Read a given nvmem cell
 980  *
 981  * @cell: nvmem cell to be read.
 982  * @len: pointer to length of cell which will be populated on successful read.
 983  *
 984  * Return: ERR_PTR() on error or a valid pointer to a char * buffer on success.
 985  * The buffer should be freed by the consumer with a kfree().
 986  */
 987 void *nvmem_cell_read(struct nvmem_cell *cell, size_t *len)
 988 {
 989         struct nvmem_device *nvmem = cell->nvmem;
 990         u8 *buf;
 991         int rc;
 992
 993         if (!nvmem)
 994                 return ERR_PTR(-EINVAL);
 995
 996         buf = kzalloc(cell->bytes, GFP_KERNEL);
 997         if (!buf)
 998                 return ERR_PTR(-ENOMEM);
 999
1000         rc = __nvmem_cell_read(nvmem, cell, buf, len);
1001         if (rc) {
1002                 kfree(buf);
1003                 return ERR_PTR(rc);
1004         }
1005
1006         return buf;
1007 }
1008 EXPORT_SYMBOL_GPL(nvmem_cell_read);
1009
1010 static inline void *nvmem_cell_prepare_write_buffer(struct nvmem_cell *cell,
1011                                                     u8 *_buf, int len)
1012 {
1013         struct nvmem_device *nvmem = cell->nvmem;
1014         int i, rc, nbits, bit_offset = cell->bit_offset;
1015         u8 v, *p, *buf, *b, pbyte, pbits;
1016
1017         nbits = cell->nbits;
1018         buf = kzalloc(cell->bytes, GFP_KERNEL);
1019         if (!buf)
1020                 return ERR_PTR(-ENOMEM);
1021
1022         memcpy(buf, _buf, len);
1023         p = b = buf;
1024
1025         if (bit_offset) {
1026                 pbyte = *b;
1027                 *b <<= bit_offset;
1028
1029                 /* setup the first byte with lsb bits from nvmem */
1030                 rc = nvmem_reg_read(nvmem, cell->offset, &v, 1);
1031                 *b++ |= GENMASK(bit_offset - 1, 0) & v;
1032
1033                 /* setup rest of the byte if any */
1034                 for (i = 1; i < cell->bytes; i++) {
1035                         /* Get last byte bits and shift them towards lsb */
1036                         pbits = pbyte >> (BITS_PER_BYTE - 1 - bit_offset);
1037                         pbyte = *b;
1038                         p = b;
1039                         *b <<= bit_offset;
1040                         *b++ |= pbits;
1041                 }
1042         }
1043
1044         /* if it's not end on byte boundary */
1045         if ((nbits + bit_offset) % BITS_PER_BYTE) {
1046                 /* setup the last byte with msb bits from nvmem */
1047                 rc = nvmem_reg_read(nvmem,
1048                                     cell->offset + cell->bytes - 1, &v, 1);
1049                 *p |= GENMASK(7, (nbits + bit_offset) % BITS_PER_BYTE) & v;
1050
1051         }
1052
1053         return buf;
1054 }
1055
1056 /**
1057  * nvmem_cell_write() - Write to a given nvmem cell
1058  *
1059  * @cell: nvmem cell to be written.
1060  * @buf: Buffer to be written.
1061  * @len: length of buffer to be written to nvmem cell.
1062  *
1063  * Return: length of bytes written or negative on failure.
1064  */
1065 int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len)
1066 {
1067         struct nvmem_device *nvmem = cell->nvmem;
1068         int rc;
1069
1070         if (!nvmem || nvmem->read_only ||
1071             (cell->bit_offset == 0 && len != cell->bytes))
1072                 return -EINVAL;
1073
1074         if (cell->bit_offset || cell->nbits) {
1075                 buf = nvmem_cell_prepare_write_buffer(cell, buf, len);
1076                 if (IS_ERR(buf))
1077                         return PTR_ERR(buf);
1078         }
1079
1080         rc = nvmem_reg_write(nvmem, cell->offset, buf, cell->bytes);
1081
1082         /* free the tmp buffer */
1083         if (cell->bit_offset || cell->nbits)
1084                 kfree(buf);
1085
1086         if (rc)
1087                 return rc;
1088
1089         return len;
1090 }
1091 EXPORT_SYMBOL_GPL(nvmem_cell_write);
1092
1093 /**
1094  * nvmem_device_cell_read() - Read a given nvmem device and cell
1095  *
1096  * @nvmem: nvmem device to read from.
1097  * @info: nvmem cell info to be read.
1098  * @buf: buffer pointer which will be populated on successful read.
1099  *
1100  * Return: length of successful bytes read on success and negative
1101  * error code on error.
1102  */
1103 ssize_t nvmem_device_cell_read(struct nvmem_device *nvmem,
1104                            struct nvmem_cell_info *info, void *buf)
1105 {
1106         struct nvmem_cell cell;
1107         int rc;
1108         ssize_t len;
1109
1110         if (!nvmem)
1111                 return -EINVAL;
1112
1113         rc = nvmem_cell_info_to_nvmem_cell(nvmem, info, &cell);
1114         if (rc)
1115                 return rc;
1116
1117         rc = __nvmem_cell_read(nvmem, &cell, buf, &len);
1118         if (rc)
1119                 return rc;
1120
1121         return len;
1122 }
1123 EXPORT_SYMBOL_GPL(nvmem_device_cell_read);
1124
1125 /**
1126  * nvmem_device_cell_write() - Write cell to a given nvmem device
1127  *
1128  * @nvmem: nvmem device to be written to.
1129  * @info: nvmem cell info to be written
1130  * @buf: buffer to be written to cell.
1131  *
1132  * Return: length of bytes written or negative error code on failure.
1133  * */
1134 int nvmem_device_cell_write(struct nvmem_device *nvmem,
1135                             struct nvmem_cell_info *info, void *buf)
1136 {
1137         struct nvmem_cell cell;
1138         int rc;
1139
1140         if (!nvmem)
1141                 return -EINVAL;
1142
1143         rc = nvmem_cell_info_to_nvmem_cell(nvmem, info, &cell);
1144         if (rc)
1145                 return rc;
1146
1147         return nvmem_cell_write(&cell, buf, cell.bytes);
1148 }
1149 EXPORT_SYMBOL_GPL(nvmem_device_cell_write);
1150
1151 /**
1152  * nvmem_device_read() - Read from a given nvmem device
1153  *
1154  * @nvmem: nvmem device to read from.
1155  * @offset: offset in nvmem device.
1156  * @bytes: number of bytes to read.
1157  * @buf: buffer pointer which will be populated on successful read.
1158  *
1159  * Return: length of successful bytes read on success and negative
1160  * error code on error.
1161  */
1162 int nvmem_device_read(struct nvmem_device *nvmem,
1163                       unsigned int offset,
1164                       size_t bytes, void *buf)
1165 {
1166         int rc;
1167
1168         if (!nvmem)
1169                 return -EINVAL;
1170
1171         rc = nvmem_reg_read(nvmem, offset, buf, bytes);
1172
1173         if (rc)
1174                 return rc;
1175
1176         return bytes;
1177 }
1178 EXPORT_SYMBOL_GPL(nvmem_device_read);
1179
1180 /**
1181  * nvmem_device_write() - Write cell to a given nvmem device
1182  *
1183  * @nvmem: nvmem device to be written to.
1184  * @offset: offset in nvmem device.
1185  * @bytes: number of bytes to write.
1186  * @buf: buffer to be written.
1187  *
1188  * Return: length of bytes written or negative error code on failure.
1189  * */
1190 int nvmem_device_write(struct nvmem_device *nvmem,
1191                        unsigned int offset,
1192                        size_t bytes, void *buf)
1193 {
1194         int rc;
1195
1196         if (!nvmem)
1197                 return -EINVAL;
1198
1199         rc = nvmem_reg_write(nvmem, offset, buf, bytes);
1200
1201         if (rc)
1202                 return rc;
1203
1204
1205         return bytes;
1206 }
1207 EXPORT_SYMBOL_GPL(nvmem_device_write);
1208
1209 static int __init nvmem_init(void)
1210 {
1211         return bus_register(&nvmem_bus_type);
1212 }
1213
1214 static void __exit nvmem_exit(void)
1215 {
1216         bus_unregister(&nvmem_bus_type);
1217 }
1218
1219 subsys_initcall(nvmem_init);
1220 module_exit(nvmem_exit);
1221
1222 MODULE_AUTHOR("Srinivas Kandagatla <srinivas.kandagatla@linaro.org");
1223 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com");
1224 MODULE_DESCRIPTION("nvmem Driver Core");
1225 MODULE_LICENSE("GPL v2");