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