drivers/nvdimm/dimm_devs.c

   1 /*
   2  * Copyright(c) 2013-2015 Intel Corporation. All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of version 2 of the GNU General Public License as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  */
  13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  14 #include <linux/vmalloc.h>
  15 #include <linux/device.h>
  16 #include <linux/ndctl.h>
  17 #include <linux/slab.h>
  18 #include <linux/io.h>
  19 #include <linux/fs.h>
  20 #include <linux/mm.h>
  21 #include "nd-core.h"
  22 #include "label.h"
  23 #include "pmem.h"
  24 #include "nd.h"
  25
  26 static DEFINE_IDA(dimm_ida);
  27
  28 /*
  29  * Retrieve bus and dimm handle and return if this bus supports
  30  * get_config_data commands
  31  */
  32 int nvdimm_check_config_data(struct device *dev)
  33 {
  34         struct nvdimm *nvdimm = to_nvdimm(dev);
  35
  36         if (!nvdimm->cmd_mask ||
  37             !test_bit(ND_CMD_GET_CONFIG_DATA, &nvdimm->cmd_mask)) {
  38                 if (test_bit(NDD_ALIASING, &nvdimm->flags))
  39                         return -ENXIO;
  40                 else
  41                         return -ENOTTY;
  42         }
  43
  44         return 0;
  45 }
  46
  47 static int validate_dimm(struct nvdimm_drvdata *ndd)
  48 {
  49         int rc;
  50
  51         if (!ndd)
  52                 return -EINVAL;
  53
  54         rc = nvdimm_check_config_data(ndd->dev);
  55         if (rc)
  56                 dev_dbg(ndd->dev, "%pf: %s error: %d\n",
  57                                 __builtin_return_address(0), __func__, rc);
  58         return rc;
  59 }
  60
  61 /**
  62  * nvdimm_init_nsarea - determine the geometry of a dimm's namespace area
  63  * @nvdimm: dimm to initialize
  64  */
  65 int nvdimm_init_nsarea(struct nvdimm_drvdata *ndd)
  66 {
  67         struct nd_cmd_get_config_size *cmd = &ndd->nsarea;
  68         struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(ndd->dev);
  69         struct nvdimm_bus_descriptor *nd_desc;
  70         int rc = validate_dimm(ndd);
  71         int cmd_rc = 0;
  72
  73         if (rc)
  74                 return rc;
  75
  76         if (cmd->config_size)
  77                 return 0; /* already valid */
  78
  79         memset(cmd, 0, sizeof(*cmd));
  80         nd_desc = nvdimm_bus->nd_desc;
  81         rc = nd_desc->ndctl(nd_desc, to_nvdimm(ndd->dev),
  82                         ND_CMD_GET_CONFIG_SIZE, cmd, sizeof(*cmd), &cmd_rc);
  83         if (rc < 0)
  84                 return rc;
  85         return cmd_rc;
  86 }
  87
  88 int nvdimm_init_config_data(struct nvdimm_drvdata *ndd)
  89 {
  90         struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(ndd->dev);
  91         struct nd_cmd_get_config_data_hdr *cmd;
  92         struct nvdimm_bus_descriptor *nd_desc;
  93         int rc = validate_dimm(ndd);
  94         u32 max_cmd_size, config_size;
  95         size_t offset;
  96
  97         if (rc)
  98                 return rc;
  99
 100         if (ndd->data)
 101                 return 0;
 102
 103         if (ndd->nsarea.status || ndd->nsarea.max_xfer == 0
 104                         || ndd->nsarea.config_size < ND_LABEL_MIN_SIZE) {
 105                 dev_dbg(ndd->dev, "failed to init config data area: (%d:%d)\n",
 106                                 ndd->nsarea.max_xfer, ndd->nsarea.config_size);
 107                 return -ENXIO;
 108         }
 109
 110         ndd->data = kvmalloc(ndd->nsarea.config_size, GFP_KERNEL);
 111         if (!ndd->data)
 112                 return -ENOMEM;
 113
 114         max_cmd_size = min_t(u32, PAGE_SIZE, ndd->nsarea.max_xfer);
 115         cmd = kzalloc(max_cmd_size + sizeof(*cmd), GFP_KERNEL);
 116         if (!cmd)
 117                 return -ENOMEM;
 118
 119         nd_desc = nvdimm_bus->nd_desc;
 120         for (config_size = ndd->nsarea.config_size, offset = 0;
 121                         config_size; config_size -= cmd->in_length,
 122                         offset += cmd->in_length) {
 123                 cmd->in_length = min(config_size, max_cmd_size);
 124                 cmd->in_offset = offset;
 125                 rc = nd_desc->ndctl(nd_desc, to_nvdimm(ndd->dev),
 126                                 ND_CMD_GET_CONFIG_DATA, cmd,
 127                                 cmd->in_length + sizeof(*cmd), NULL);
 128                 if (rc || cmd->status) {
 129                         rc = -ENXIO;
 130                         break;
 131                 }
 132                 memcpy(ndd->data + offset, cmd->out_buf, cmd->in_length);
 133         }
 134         dev_dbg(ndd->dev, "%s: len: %zu rc: %d\n", __func__, offset, rc);
 135         kfree(cmd);
 136
 137         return rc;
 138 }
 139
 140 int nvdimm_set_config_data(struct nvdimm_drvdata *ndd, size_t offset,
 141                 void *buf, size_t len)
 142 {
 143         int rc = validate_dimm(ndd);
 144         size_t max_cmd_size, buf_offset;
 145         struct nd_cmd_set_config_hdr *cmd;
 146         struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(ndd->dev);
 147         struct nvdimm_bus_descriptor *nd_desc = nvdimm_bus->nd_desc;
 148
 149         if (rc)
 150                 return rc;
 151
 152         if (!ndd->data)
 153                 return -ENXIO;
 154
 155         if (offset + len > ndd->nsarea.config_size)
 156                 return -ENXIO;
 157
 158         max_cmd_size = min_t(u32, PAGE_SIZE, len);
 159         max_cmd_size = min_t(u32, max_cmd_size, ndd->nsarea.max_xfer);
 160         cmd = kzalloc(max_cmd_size + sizeof(*cmd) + sizeof(u32), GFP_KERNEL);
 161         if (!cmd)
 162                 return -ENOMEM;
 163
 164         for (buf_offset = 0; len; len -= cmd->in_length,
 165                         buf_offset += cmd->in_length) {
 166                 size_t cmd_size;
 167                 u32 *status;
 168
 169                 cmd->in_offset = offset + buf_offset;
 170                 cmd->in_length = min(max_cmd_size, len);
 171                 memcpy(cmd->in_buf, buf + buf_offset, cmd->in_length);
 172
 173                 /* status is output in the last 4-bytes of the command buffer */
 174                 cmd_size = sizeof(*cmd) + cmd->in_length + sizeof(u32);
 175                 status = ((void *) cmd) + cmd_size - sizeof(u32);
 176
 177                 rc = nd_desc->ndctl(nd_desc, to_nvdimm(ndd->dev),
 178                                 ND_CMD_SET_CONFIG_DATA, cmd, cmd_size, NULL);
 179                 if (rc || *status) {
 180                         rc = rc ? rc : -ENXIO;
 181                         break;
 182                 }
 183         }
 184         kfree(cmd);
 185
 186         return rc;
 187 }
 188
 189 void nvdimm_set_aliasing(struct device *dev)
 190 {
 191         struct nvdimm *nvdimm = to_nvdimm(dev);
 192
 193         set_bit(NDD_ALIASING, &nvdimm->flags);
 194 }
 195
 196 void nvdimm_set_locked(struct device *dev)
 197 {
 198         struct nvdimm *nvdimm = to_nvdimm(dev);
 199
 200         set_bit(NDD_LOCKED, &nvdimm->flags);
 201 }
 202
 203 static void nvdimm_release(struct device *dev)
 204 {
 205         struct nvdimm *nvdimm = to_nvdimm(dev);
 206
 207         ida_simple_remove(&dimm_ida, nvdimm->id);
 208         kfree(nvdimm);
 209 }
 210
 211 static struct device_type nvdimm_device_type = {
 212         .name = "nvdimm",
 213         .release = nvdimm_release,
 214 };
 215
 216 bool is_nvdimm(struct device *dev)
 217 {
 218         return dev->type == &nvdimm_device_type;
 219 }
 220
 221 struct nvdimm *to_nvdimm(struct device *dev)
 222 {
 223         struct nvdimm *nvdimm = container_of(dev, struct nvdimm, dev);
 224
 225         WARN_ON(!is_nvdimm(dev));
 226         return nvdimm;
 227 }
 228 EXPORT_SYMBOL_GPL(to_nvdimm);
 229
 230 struct nvdimm *nd_blk_region_to_dimm(struct nd_blk_region *ndbr)
 231 {
 232         struct nd_region *nd_region = &ndbr->nd_region;
 233         struct nd_mapping *nd_mapping = &nd_region->mapping[0];
 234
 235         return nd_mapping->nvdimm;
 236 }
 237 EXPORT_SYMBOL_GPL(nd_blk_region_to_dimm);
 238
 239 unsigned long nd_blk_memremap_flags(struct nd_blk_region *ndbr)
 240 {
 241         /* pmem mapping properties are private to libnvdimm */
 242         return ARCH_MEMREMAP_PMEM;
 243 }
 244 EXPORT_SYMBOL_GPL(nd_blk_memremap_flags);
 245
 246 struct nvdimm_drvdata *to_ndd(struct nd_mapping *nd_mapping)
 247 {
 248         struct nvdimm *nvdimm = nd_mapping->nvdimm;
 249
 250         WARN_ON_ONCE(!is_nvdimm_bus_locked(&nvdimm->dev));
 251
 252         return dev_get_drvdata(&nvdimm->dev);
 253 }
 254 EXPORT_SYMBOL(to_ndd);
 255
 256 void nvdimm_drvdata_release(struct kref *kref)
 257 {
 258         struct nvdimm_drvdata *ndd = container_of(kref, typeof(*ndd), kref);
 259         struct device *dev = ndd->dev;
 260         struct resource *res, *_r;
 261
 262         dev_dbg(dev, "%s\n", __func__);
 263
 264         nvdimm_bus_lock(dev);
 265         for_each_dpa_resource_safe(ndd, res, _r)
 266                 nvdimm_free_dpa(ndd, res);
 267         nvdimm_bus_unlock(dev);
 268
 269         kvfree(ndd->data);
 270         kfree(ndd);
 271         put_device(dev);
 272 }
 273
 274 void get_ndd(struct nvdimm_drvdata *ndd)
 275 {
 276         kref_get(&ndd->kref);
 277 }
 278
 279 void put_ndd(struct nvdimm_drvdata *ndd)
 280 {
 281         if (ndd)
 282                 kref_put(&ndd->kref, nvdimm_drvdata_release);
 283 }
 284
 285 const char *nvdimm_name(struct nvdimm *nvdimm)
 286 {
 287         return dev_name(&nvdimm->dev);
 288 }
 289 EXPORT_SYMBOL_GPL(nvdimm_name);
 290
 291 struct kobject *nvdimm_kobj(struct nvdimm *nvdimm)
 292 {
 293         return &nvdimm->dev.kobj;
 294 }
 295 EXPORT_SYMBOL_GPL(nvdimm_kobj);
 296
 297 unsigned long nvdimm_cmd_mask(struct nvdimm *nvdimm)
 298 {
 299         return nvdimm->cmd_mask;
 300 }
 301 EXPORT_SYMBOL_GPL(nvdimm_cmd_mask);
 302
 303 void *nvdimm_provider_data(struct nvdimm *nvdimm)
 304 {
 305         if (nvdimm)
 306                 return nvdimm->provider_data;
 307         return NULL;
 308 }
 309 EXPORT_SYMBOL_GPL(nvdimm_provider_data);
 310
 311 static ssize_t commands_show(struct device *dev,
 312                 struct device_attribute *attr, char *buf)
 313 {
 314         struct nvdimm *nvdimm = to_nvdimm(dev);
 315         int cmd, len = 0;
 316
 317         if (!nvdimm->cmd_mask)
 318                 return sprintf(buf, "\n");
 319
 320         for_each_set_bit(cmd, &nvdimm->cmd_mask, BITS_PER_LONG)
 321                 len += sprintf(buf + len, "%s ", nvdimm_cmd_name(cmd));
 322         len += sprintf(buf + len, "\n");
 323         return len;
 324 }
 325 static DEVICE_ATTR_RO(commands);
 326
 327 static ssize_t state_show(struct device *dev, struct device_attribute *attr,
 328                 char *buf)
 329 {
 330         struct nvdimm *nvdimm = to_nvdimm(dev);
 331
 332         /*
 333          * The state may be in the process of changing, userspace should
 334          * quiesce probing if it wants a static answer
 335          */
 336         nvdimm_bus_lock(dev);
 337         nvdimm_bus_unlock(dev);
 338         return sprintf(buf, "%s\n", atomic_read(&nvdimm->busy)
 339                         ? "active" : "idle");
 340 }
 341 static DEVICE_ATTR_RO(state);
 342
 343 static ssize_t available_slots_show(struct device *dev,
 344                 struct device_attribute *attr, char *buf)
 345 {
 346         struct nvdimm_drvdata *ndd = dev_get_drvdata(dev);
 347         ssize_t rc;
 348         u32 nfree;
 349
 350         if (!ndd)
 351                 return -ENXIO;
 352
 353         nvdimm_bus_lock(dev);
 354         nfree = nd_label_nfree(ndd);
 355         if (nfree - 1 > nfree) {
 356                 dev_WARN_ONCE(dev, 1, "we ate our last label?\n");
 357                 nfree = 0;
 358         } else
 359                 nfree--;
 360         rc = sprintf(buf, "%d\n", nfree);
 361         nvdimm_bus_unlock(dev);
 362         return rc;
 363 }
 364 static DEVICE_ATTR_RO(available_slots);
 365
 366 static struct attribute *nvdimm_attributes[] = {
 367         &dev_attr_state.attr,
 368         &dev_attr_commands.attr,
 369         &dev_attr_available_slots.attr,
 370         NULL,
 371 };
 372
 373 struct attribute_group nvdimm_attribute_group = {
 374         .attrs = nvdimm_attributes,
 375 };
 376 EXPORT_SYMBOL_GPL(nvdimm_attribute_group);
 377
 378 struct nvdimm *nvdimm_create(struct nvdimm_bus *nvdimm_bus, void *provider_data,
 379                 const struct attribute_group **groups, unsigned long flags,
 380                 unsigned long cmd_mask, int num_flush,
 381                 struct resource *flush_wpq)
 382 {
 383         struct nvdimm *nvdimm = kzalloc(sizeof(*nvdimm), GFP_KERNEL);
 384         struct device *dev;
 385
 386         if (!nvdimm)
 387                 return NULL;
 388
 389         nvdimm->id = ida_simple_get(&dimm_ida, 0, 0, GFP_KERNEL);
 390         if (nvdimm->id < 0) {
 391                 kfree(nvdimm);
 392                 return NULL;
 393         }
 394         nvdimm->provider_data = provider_data;
 395         nvdimm->flags = flags;
 396         nvdimm->cmd_mask = cmd_mask;
 397         nvdimm->num_flush = num_flush;
 398         nvdimm->flush_wpq = flush_wpq;
 399         atomic_set(&nvdimm->busy, 0);
 400         dev = &nvdimm->dev;
 401         dev_set_name(dev, "nmem%d", nvdimm->id);
 402         dev->parent = &nvdimm_bus->dev;
 403         dev->type = &nvdimm_device_type;
 404         dev->devt = MKDEV(nvdimm_major, nvdimm->id);
 405         dev->groups = groups;
 406         nd_device_register(dev);
 407
 408         return nvdimm;
 409 }
 410 EXPORT_SYMBOL_GPL(nvdimm_create);
 411
 412 int alias_dpa_busy(struct device *dev, void *data)
 413 {
 414         resource_size_t map_end, blk_start, new;
 415         struct blk_alloc_info *info = data;
 416         struct nd_mapping *nd_mapping;
 417         struct nd_region *nd_region;
 418         struct nvdimm_drvdata *ndd;
 419         struct resource *res;
 420         int i;
 421
 422         if (!is_memory(dev))
 423                 return 0;
 424
 425         nd_region = to_nd_region(dev);
 426         for (i = 0; i < nd_region->ndr_mappings; i++) {
 427                 nd_mapping  = &nd_region->mapping[i];
 428                 if (nd_mapping->nvdimm == info->nd_mapping->nvdimm)
 429                         break;
 430         }
 431
 432         if (i >= nd_region->ndr_mappings)
 433                 return 0;
 434
 435         ndd = to_ndd(nd_mapping);
 436         map_end = nd_mapping->start + nd_mapping->size - 1;
 437         blk_start = nd_mapping->start;
 438
 439         /*
 440          * In the allocation case ->res is set to free space that we are
 441          * looking to validate against PMEM aliasing collision rules
 442          * (i.e. BLK is allocated after all aliased PMEM).
 443          */
 444         if (info->res) {
 445                 if (info->res->start >= nd_mapping->start
 446                                 && info->res->start < map_end)
 447                         /* pass */;
 448                 else
 449                         return 0;
 450         }
 451
 452  retry:
 453         /*
 454          * Find the free dpa from the end of the last pmem allocation to
 455          * the end of the interleave-set mapping.
 456          */
 457         for_each_dpa_resource(ndd, res) {
 458                 if (strncmp(res->name, "pmem", 4) != 0)
 459                         continue;
 460                 if ((res->start >= blk_start && res->start < map_end)
 461                                 || (res->end >= blk_start
 462                                         && res->end <= map_end)) {
 463                         new = max(blk_start, min(map_end + 1, res->end + 1));
 464                         if (new != blk_start) {
 465                                 blk_start = new;
 466                                 goto retry;
 467                         }
 468                 }
 469         }
 470
 471         /* update the free space range with the probed blk_start */
 472         if (info->res && blk_start > info->res->start) {
 473                 info->res->start = max(info->res->start, blk_start);
 474                 if (info->res->start > info->res->end)
 475                         info->res->end = info->res->start - 1;
 476                 return 1;
 477         }
 478
 479         info->available -= blk_start - nd_mapping->start;
 480
 481         return 0;
 482 }
 483
 484 /**
 485  * nd_blk_available_dpa - account the unused dpa of BLK region
 486  * @nd_mapping: container of dpa-resource-root + labels
 487  *
 488  * Unlike PMEM, BLK namespaces can occupy discontiguous DPA ranges, but
 489  * we arrange for them to never start at an lower dpa than the last
 490  * PMEM allocation in an aliased region.
 491  */
 492 resource_size_t nd_blk_available_dpa(struct nd_region *nd_region)
 493 {
 494         struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(&nd_region->dev);
 495         struct nd_mapping *nd_mapping = &nd_region->mapping[0];
 496         struct nvdimm_drvdata *ndd = to_ndd(nd_mapping);
 497         struct blk_alloc_info info = {
 498                 .nd_mapping = nd_mapping,
 499                 .available = nd_mapping->size,
 500                 .res = NULL,
 501         };
 502         struct resource *res;
 503
 504         if (!ndd)
 505                 return 0;
 506
 507         device_for_each_child(&nvdimm_bus->dev, &info, alias_dpa_busy);
 508
 509         /* now account for busy blk allocations in unaliased dpa */
 510         for_each_dpa_resource(ndd, res) {
 511                 if (strncmp(res->name, "blk", 3) != 0)
 512                         continue;
 513                 info.available -= resource_size(res);
 514         }
 515
 516         return info.available;
 517 }
 518
 519 /**
 520  * nd_pmem_available_dpa - for the given dimm+region account unallocated dpa
 521  * @nd_mapping: container of dpa-resource-root + labels
 522  * @nd_region: constrain available space check to this reference region
 523  * @overlap: calculate available space assuming this level of overlap
 524  *
 525  * Validate that a PMEM label, if present, aligns with the start of an
 526  * interleave set and truncate the available size at the lowest BLK
 527  * overlap point.
 528  *
 529  * The expectation is that this routine is called multiple times as it
 530  * probes for the largest BLK encroachment for any single member DIMM of
 531  * the interleave set.  Once that value is determined the PMEM-limit for
 532  * the set can be established.
 533  */
 534 resource_size_t nd_pmem_available_dpa(struct nd_region *nd_region,
 535                 struct nd_mapping *nd_mapping, resource_size_t *overlap)
 536 {
 537         resource_size_t map_start, map_end, busy = 0, available, blk_start;
 538         struct nvdimm_drvdata *ndd = to_ndd(nd_mapping);
 539         struct resource *res;
 540         const char *reason;
 541
 542         if (!ndd)
 543                 return 0;
 544
 545         map_start = nd_mapping->start;
 546         map_end = map_start + nd_mapping->size - 1;
 547         blk_start = max(map_start, map_end + 1 - *overlap);
 548         for_each_dpa_resource(ndd, res) {
 549                 if (res->start >= map_start && res->start < map_end) {
 550                         if (strncmp(res->name, "blk", 3) == 0)
 551                                 blk_start = min(blk_start,
 552                                                 max(map_start, res->start));
 553                         else if (res->end > map_end) {
 554                                 reason = "misaligned to iset";
 555                                 goto err;
 556                         } else
 557                                 busy += resource_size(res);
 558                 } else if (res->end >= map_start && res->end <= map_end) {
 559                         if (strncmp(res->name, "blk", 3) == 0) {
 560                                 /*
 561                                  * If a BLK allocation overlaps the start of
 562                                  * PMEM the entire interleave set may now only
 563                                  * be used for BLK.
 564                                  */
 565                                 blk_start = map_start;
 566                         } else
 567                                 busy += resource_size(res);
 568                 } else if (map_start > res->start && map_start < res->end) {
 569                         /* total eclipse of the mapping */
 570                         busy += nd_mapping->size;
 571                         blk_start = map_start;
 572                 }
 573         }
 574
 575         *overlap = map_end + 1 - blk_start;
 576         available = blk_start - map_start;
 577         if (busy < available)
 578                 return available - busy;
 579         return 0;
 580
 581  err:
 582         nd_dbg_dpa(nd_region, ndd, res, "%s\n", reason);
 583         return 0;
 584 }
 585
 586 void nvdimm_free_dpa(struct nvdimm_drvdata *ndd, struct resource *res)
 587 {
 588         WARN_ON_ONCE(!is_nvdimm_bus_locked(ndd->dev));
 589         kfree(res->name);
 590         __release_region(&ndd->dpa, res->start, resource_size(res));
 591 }
 592
 593 struct resource *nvdimm_allocate_dpa(struct nvdimm_drvdata *ndd,
 594                 struct nd_label_id *label_id, resource_size_t start,
 595                 resource_size_t n)
 596 {
 597         char *name = kmemdup(label_id, sizeof(*label_id), GFP_KERNEL);
 598         struct resource *res;
 599
 600         if (!name)
 601                 return NULL;
 602
 603         WARN_ON_ONCE(!is_nvdimm_bus_locked(ndd->dev));
 604         res = __request_region(&ndd->dpa, start, n, name, 0);
 605         if (!res)
 606                 kfree(name);
 607         return res;
 608 }
 609
 610 /**
 611  * nvdimm_allocated_dpa - sum up the dpa currently allocated to this label_id
 612  * @nvdimm: container of dpa-resource-root + labels
 613  * @label_id: dpa resource name of the form {pmem|blk}-<human readable uuid>
 614  */
 615 resource_size_t nvdimm_allocated_dpa(struct nvdimm_drvdata *ndd,
 616                 struct nd_label_id *label_id)
 617 {
 618         resource_size_t allocated = 0;
 619         struct resource *res;
 620
 621         for_each_dpa_resource(ndd, res)
 622                 if (strcmp(res->name, label_id->id) == 0)
 623                         allocated += resource_size(res);
 624
 625         return allocated;
 626 }
 627
 628 static int count_dimms(struct device *dev, void *c)
 629 {
 630         int *count = c;
 631
 632         if (is_nvdimm(dev))
 633                 (*count)++;
 634         return 0;
 635 }
 636
 637 int nvdimm_bus_check_dimm_count(struct nvdimm_bus *nvdimm_bus, int dimm_count)
 638 {
 639         int count = 0;
 640         /* Flush any possible dimm registration failures */
 641         nd_synchronize();
 642
 643         device_for_each_child(&nvdimm_bus->dev, &count, count_dimms);
 644         dev_dbg(&nvdimm_bus->dev, "%s: count: %d\n", __func__, count);
 645         if (count != dimm_count)
 646                 return -ENXIO;
 647         return 0;
 648 }
 649 EXPORT_SYMBOL_GPL(nvdimm_bus_check_dimm_count);
 650
 651 void __exit nvdimm_devs_exit(void)
 652 {
 653         ida_destroy(&dimm_ida);
 654 }