drivers/dax/bus.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright(c) 2017-2018 Intel Corporation. All rights reserved. */
   3 #include <linux/memremap.h>
   4 #include <linux/device.h>
   5 #include <linux/mutex.h>
   6 #include <linux/list.h>
   7 #include <linux/slab.h>
   8 #include <linux/dax.h>
   9 #include <linux/io.h>
  10 #include "dax-private.h"
  11 #include "bus.h"
  12
  13 static struct class *dax_class;
  14
  15 static DEFINE_MUTEX(dax_bus_lock);
  16
  17 #define DAX_NAME_LEN 30
  18 struct dax_id {
  19         struct list_head list;
  20         char dev_name[DAX_NAME_LEN];
  21 };
  22
  23 static int dax_bus_uevent(struct device *dev, struct kobj_uevent_env *env)
  24 {
  25         /*
  26          * We only ever expect to handle device-dax instances, i.e. the
  27          * @type argument to MODULE_ALIAS_DAX_DEVICE() is always zero
  28          */
  29         return add_uevent_var(env, "MODALIAS=" DAX_DEVICE_MODALIAS_FMT, 0);
  30 }
  31
  32 static struct dax_device_driver *to_dax_drv(struct device_driver *drv)
  33 {
  34         return container_of(drv, struct dax_device_driver, drv);
  35 }
  36
  37 static struct dax_id *__dax_match_id(struct dax_device_driver *dax_drv,
  38                 const char *dev_name)
  39 {
  40         struct dax_id *dax_id;
  41
  42         lockdep_assert_held(&dax_bus_lock);
  43
  44         list_for_each_entry(dax_id, &dax_drv->ids, list)
  45                 if (sysfs_streq(dax_id->dev_name, dev_name))
  46                         return dax_id;
  47         return NULL;
  48 }
  49
  50 static int dax_match_id(struct dax_device_driver *dax_drv, struct device *dev)
  51 {
  52         int match;
  53
  54         mutex_lock(&dax_bus_lock);
  55         match = !!__dax_match_id(dax_drv, dev_name(dev));
  56         mutex_unlock(&dax_bus_lock);
  57
  58         return match;
  59 }
  60
  61 enum id_action {
  62         ID_REMOVE,
  63         ID_ADD,
  64 };
  65
  66 static ssize_t do_id_store(struct device_driver *drv, const char *buf,
  67                 size_t count, enum id_action action)
  68 {
  69         struct dax_device_driver *dax_drv = to_dax_drv(drv);
  70         unsigned int region_id, id;
  71         char devname[DAX_NAME_LEN];
  72         struct dax_id *dax_id;
  73         ssize_t rc = count;
  74         int fields;
  75
  76         fields = sscanf(buf, "dax%d.%d", &region_id, &id);
  77         if (fields != 2)
  78                 return -EINVAL;
  79         sprintf(devname, "dax%d.%d", region_id, id);
  80         if (!sysfs_streq(buf, devname))
  81                 return -EINVAL;
  82
  83         mutex_lock(&dax_bus_lock);
  84         dax_id = __dax_match_id(dax_drv, buf);
  85         if (!dax_id) {
  86                 if (action == ID_ADD) {
  87                         dax_id = kzalloc(sizeof(*dax_id), GFP_KERNEL);
  88                         if (dax_id) {
  89                                 strncpy(dax_id->dev_name, buf, DAX_NAME_LEN);
  90                                 list_add(&dax_id->list, &dax_drv->ids);
  91                         } else
  92                                 rc = -ENOMEM;
  93                 } else
  94                         /* nothing to remove */;
  95         } else if (action == ID_REMOVE) {
  96                 list_del(&dax_id->list);
  97                 kfree(dax_id);
  98         } else
  99                 /* dax_id already added */;
 100         mutex_unlock(&dax_bus_lock);
 101
 102         if (rc < 0)
 103                 return rc;
 104         if (action == ID_ADD)
 105                 rc = driver_attach(drv);
 106         if (rc)
 107                 return rc;
 108         return count;
 109 }
 110
 111 static ssize_t new_id_store(struct device_driver *drv, const char *buf,
 112                 size_t count)
 113 {
 114         return do_id_store(drv, buf, count, ID_ADD);
 115 }
 116 static DRIVER_ATTR_WO(new_id);
 117
 118 static ssize_t remove_id_store(struct device_driver *drv, const char *buf,
 119                 size_t count)
 120 {
 121         return do_id_store(drv, buf, count, ID_REMOVE);
 122 }
 123 static DRIVER_ATTR_WO(remove_id);
 124
 125 static struct attribute *dax_drv_attrs[] = {
 126         &driver_attr_new_id.attr,
 127         &driver_attr_remove_id.attr,
 128         NULL,
 129 };
 130 ATTRIBUTE_GROUPS(dax_drv);
 131
 132 static int dax_bus_match(struct device *dev, struct device_driver *drv);
 133
 134 static bool is_static(struct dax_region *dax_region)
 135 {
 136         return (dax_region->res.flags & IORESOURCE_DAX_STATIC) != 0;
 137 }
 138
 139 static u64 dev_dax_size(struct dev_dax *dev_dax)
 140 {
 141         u64 size = 0;
 142         int i;
 143
 144         device_lock_assert(&dev_dax->dev);
 145
 146         for (i = 0; i < dev_dax->nr_range; i++)
 147                 size += range_len(&dev_dax->ranges[i].range);
 148
 149         return size;
 150 }
 151
 152 static int dax_bus_probe(struct device *dev)
 153 {
 154         struct dax_device_driver *dax_drv = to_dax_drv(dev->driver);
 155         struct dev_dax *dev_dax = to_dev_dax(dev);
 156         struct dax_region *dax_region = dev_dax->region;
 157         int rc;
 158
 159         if (dev_dax_size(dev_dax) == 0 || dev_dax->id < 0)
 160                 return -ENXIO;
 161
 162         rc = dax_drv->probe(dev_dax);
 163
 164         if (rc || is_static(dax_region))
 165                 return rc;
 166
 167         /*
 168          * Track new seed creation only after successful probe of the
 169          * previous seed.
 170          */
 171         if (dax_region->seed == dev)
 172                 dax_region->seed = NULL;
 173
 174         return 0;
 175 }
 176
 177 static int dax_bus_remove(struct device *dev)
 178 {
 179         struct dax_device_driver *dax_drv = to_dax_drv(dev->driver);
 180         struct dev_dax *dev_dax = to_dev_dax(dev);
 181
 182         return dax_drv->remove(dev_dax);
 183 }
 184
 185 static struct bus_type dax_bus_type = {
 186         .name = "dax",
 187         .uevent = dax_bus_uevent,
 188         .match = dax_bus_match,
 189         .probe = dax_bus_probe,
 190         .remove = dax_bus_remove,
 191         .drv_groups = dax_drv_groups,
 192 };
 193
 194 static int dax_bus_match(struct device *dev, struct device_driver *drv)
 195 {
 196         struct dax_device_driver *dax_drv = to_dax_drv(drv);
 197
 198         /*
 199          * All but the 'device-dax' driver, which has 'match_always'
 200          * set, requires an exact id match.
 201          */
 202         if (dax_drv->match_always)
 203                 return 1;
 204
 205         return dax_match_id(dax_drv, dev);
 206 }
 207
 208 /*
 209  * Rely on the fact that drvdata is set before the attributes are
 210  * registered, and that the attributes are unregistered before drvdata
 211  * is cleared to assume that drvdata is always valid.
 212  */
 213 static ssize_t id_show(struct device *dev,
 214                 struct device_attribute *attr, char *buf)
 215 {
 216         struct dax_region *dax_region = dev_get_drvdata(dev);
 217
 218         return sprintf(buf, "%d\n", dax_region->id);
 219 }
 220 static DEVICE_ATTR_RO(id);
 221
 222 static ssize_t region_size_show(struct device *dev,
 223                 struct device_attribute *attr, char *buf)
 224 {
 225         struct dax_region *dax_region = dev_get_drvdata(dev);
 226
 227         return sprintf(buf, "%llu\n", (unsigned long long)
 228                         resource_size(&dax_region->res));
 229 }
 230 static struct device_attribute dev_attr_region_size = __ATTR(size, 0444,
 231                 region_size_show, NULL);
 232
 233 static ssize_t region_align_show(struct device *dev,
 234                 struct device_attribute *attr, char *buf)
 235 {
 236         struct dax_region *dax_region = dev_get_drvdata(dev);
 237
 238         return sprintf(buf, "%u\n", dax_region->align);
 239 }
 240 static struct device_attribute dev_attr_region_align =
 241                 __ATTR(align, 0400, region_align_show, NULL);
 242
 243 #define for_each_dax_region_resource(dax_region, res) \
 244         for (res = (dax_region)->res.child; res; res = res->sibling)
 245
 246 static unsigned long long dax_region_avail_size(struct dax_region *dax_region)
 247 {
 248         resource_size_t size = resource_size(&dax_region->res);
 249         struct resource *res;
 250
 251         device_lock_assert(dax_region->dev);
 252
 253         for_each_dax_region_resource(dax_region, res)
 254                 size -= resource_size(res);
 255         return size;
 256 }
 257
 258 static ssize_t available_size_show(struct device *dev,
 259                 struct device_attribute *attr, char *buf)
 260 {
 261         struct dax_region *dax_region = dev_get_drvdata(dev);
 262         unsigned long long size;
 263
 264         device_lock(dev);
 265         size = dax_region_avail_size(dax_region);
 266         device_unlock(dev);
 267
 268         return sprintf(buf, "%llu\n", size);
 269 }
 270 static DEVICE_ATTR_RO(available_size);
 271
 272 static ssize_t seed_show(struct device *dev,
 273                 struct device_attribute *attr, char *buf)
 274 {
 275         struct dax_region *dax_region = dev_get_drvdata(dev);
 276         struct device *seed;
 277         ssize_t rc;
 278
 279         if (is_static(dax_region))
 280                 return -EINVAL;
 281
 282         device_lock(dev);
 283         seed = dax_region->seed;
 284         rc = sprintf(buf, "%s\n", seed ? dev_name(seed) : "");
 285         device_unlock(dev);
 286
 287         return rc;
 288 }
 289 static DEVICE_ATTR_RO(seed);
 290
 291 static ssize_t create_show(struct device *dev,
 292                 struct device_attribute *attr, char *buf)
 293 {
 294         struct dax_region *dax_region = dev_get_drvdata(dev);
 295         struct device *youngest;
 296         ssize_t rc;
 297
 298         if (is_static(dax_region))
 299                 return -EINVAL;
 300
 301         device_lock(dev);
 302         youngest = dax_region->youngest;
 303         rc = sprintf(buf, "%s\n", youngest ? dev_name(youngest) : "");
 304         device_unlock(dev);
 305
 306         return rc;
 307 }
 308
 309 static ssize_t create_store(struct device *dev, struct device_attribute *attr,
 310                 const char *buf, size_t len)
 311 {
 312         struct dax_region *dax_region = dev_get_drvdata(dev);
 313         unsigned long long avail;
 314         ssize_t rc;
 315         int val;
 316
 317         if (is_static(dax_region))
 318                 return -EINVAL;
 319
 320         rc = kstrtoint(buf, 0, &val);
 321         if (rc)
 322                 return rc;
 323         if (val != 1)
 324                 return -EINVAL;
 325
 326         device_lock(dev);
 327         avail = dax_region_avail_size(dax_region);
 328         if (avail == 0)
 329                 rc = -ENOSPC;
 330         else {
 331                 struct dev_dax_data data = {
 332                         .dax_region = dax_region,
 333                         .size = 0,
 334                         .id = -1,
 335                 };
 336                 struct dev_dax *dev_dax = devm_create_dev_dax(&data);
 337
 338                 if (IS_ERR(dev_dax))
 339                         rc = PTR_ERR(dev_dax);
 340                 else {
 341                         /*
 342                          * In support of crafting multiple new devices
 343                          * simultaneously multiple seeds can be created,
 344                          * but only the first one that has not been
 345                          * successfully bound is tracked as the region
 346                          * seed.
 347                          */
 348                         if (!dax_region->seed)
 349                                 dax_region->seed = &dev_dax->dev;
 350                         dax_region->youngest = &dev_dax->dev;
 351                         rc = len;
 352                 }
 353         }
 354         device_unlock(dev);
 355
 356         return rc;
 357 }
 358 static DEVICE_ATTR_RW(create);
 359
 360 void kill_dev_dax(struct dev_dax *dev_dax)
 361 {
 362         struct dax_device *dax_dev = dev_dax->dax_dev;
 363         struct inode *inode = dax_inode(dax_dev);
 364
 365         kill_dax(dax_dev);
 366         unmap_mapping_range(inode->i_mapping, 0, 0, 1);
 367 }
 368 EXPORT_SYMBOL_GPL(kill_dev_dax);
 369
 370 static void trim_dev_dax_range(struct dev_dax *dev_dax)
 371 {
 372         int i = dev_dax->nr_range - 1;
 373         struct range *range = &dev_dax->ranges[i].range;
 374         struct dax_region *dax_region = dev_dax->region;
 375
 376         device_lock_assert(dax_region->dev);
 377         dev_dbg(&dev_dax->dev, "delete range[%d]: %#llx:%#llx\n", i,
 378                 (unsigned long long)range->start,
 379                 (unsigned long long)range->end);
 380
 381         __release_region(&dax_region->res, range->start, range_len(range));
 382         if (--dev_dax->nr_range == 0) {
 383                 kfree(dev_dax->ranges);
 384                 dev_dax->ranges = NULL;
 385         }
 386 }
 387
 388 static void free_dev_dax_ranges(struct dev_dax *dev_dax)
 389 {
 390         while (dev_dax->nr_range)
 391                 trim_dev_dax_range(dev_dax);
 392 }
 393
 394 static void unregister_dev_dax(void *dev)
 395 {
 396         struct dev_dax *dev_dax = to_dev_dax(dev);
 397
 398         dev_dbg(dev, "%s\n", __func__);
 399
 400         kill_dev_dax(dev_dax);
 401         free_dev_dax_ranges(dev_dax);
 402         device_del(dev);
 403         put_device(dev);
 404 }
 405
 406 /* a return value >= 0 indicates this invocation invalidated the id */
 407 static int __free_dev_dax_id(struct dev_dax *dev_dax)
 408 {
 409         struct dax_region *dax_region = dev_dax->region;
 410         struct device *dev = &dev_dax->dev;
 411         int rc = dev_dax->id;
 412
 413         device_lock_assert(dev);
 414
 415         if (is_static(dax_region) || dev_dax->id < 0)
 416                 return -1;
 417         ida_free(&dax_region->ida, dev_dax->id);
 418         dev_dax->id = -1;
 419         return rc;
 420 }
 421
 422 static int free_dev_dax_id(struct dev_dax *dev_dax)
 423 {
 424         struct device *dev = &dev_dax->dev;
 425         int rc;
 426
 427         device_lock(dev);
 428         rc = __free_dev_dax_id(dev_dax);
 429         device_unlock(dev);
 430         return rc;
 431 }
 432
 433 static ssize_t delete_store(struct device *dev, struct device_attribute *attr,
 434                 const char *buf, size_t len)
 435 {
 436         struct dax_region *dax_region = dev_get_drvdata(dev);
 437         struct dev_dax *dev_dax;
 438         struct device *victim;
 439         bool do_del = false;
 440         int rc;
 441
 442         if (is_static(dax_region))
 443                 return -EINVAL;
 444
 445         victim = device_find_child_by_name(dax_region->dev, buf);
 446         if (!victim)
 447                 return -ENXIO;
 448
 449         device_lock(dev);
 450         device_lock(victim);
 451         dev_dax = to_dev_dax(victim);
 452         if (victim->driver || dev_dax_size(dev_dax))
 453                 rc = -EBUSY;
 454         else {
 455                 /*
 456                  * Invalidate the device so it does not become active
 457                  * again, but always preserve device-id-0 so that
 458                  * /sys/bus/dax/ is guaranteed to be populated while any
 459                  * dax_region is registered.
 460                  */
 461                 if (dev_dax->id > 0) {
 462                         do_del = __free_dev_dax_id(dev_dax) >= 0;
 463                         rc = len;
 464                         if (dax_region->seed == victim)
 465                                 dax_region->seed = NULL;
 466                         if (dax_region->youngest == victim)
 467                                 dax_region->youngest = NULL;
 468                 } else
 469                         rc = -EBUSY;
 470         }
 471         device_unlock(victim);
 472
 473         /* won the race to invalidate the device, clean it up */
 474         if (do_del)
 475                 devm_release_action(dev, unregister_dev_dax, victim);
 476         device_unlock(dev);
 477         put_device(victim);
 478
 479         return rc;
 480 }
 481 static DEVICE_ATTR_WO(delete);
 482
 483 static umode_t dax_region_visible(struct kobject *kobj, struct attribute *a,
 484                 int n)
 485 {
 486         struct device *dev = container_of(kobj, struct device, kobj);
 487         struct dax_region *dax_region = dev_get_drvdata(dev);
 488
 489         if (is_static(dax_region))
 490                 if (a == &dev_attr_available_size.attr
 491                                 || a == &dev_attr_create.attr
 492                                 || a == &dev_attr_seed.attr
 493                                 || a == &dev_attr_delete.attr)
 494                         return 0;
 495         return a->mode;
 496 }
 497
 498 static struct attribute *dax_region_attributes[] = {
 499         &dev_attr_available_size.attr,
 500         &dev_attr_region_size.attr,
 501         &dev_attr_region_align.attr,
 502         &dev_attr_create.attr,
 503         &dev_attr_seed.attr,
 504         &dev_attr_delete.attr,
 505         &dev_attr_id.attr,
 506         NULL,
 507 };
 508
 509 static const struct attribute_group dax_region_attribute_group = {
 510         .name = "dax_region",
 511         .attrs = dax_region_attributes,
 512         .is_visible = dax_region_visible,
 513 };
 514
 515 static const struct attribute_group *dax_region_attribute_groups[] = {
 516         &dax_region_attribute_group,
 517         NULL,
 518 };
 519
 520 static void dax_region_free(struct kref *kref)
 521 {
 522         struct dax_region *dax_region;
 523
 524         dax_region = container_of(kref, struct dax_region, kref);
 525         kfree(dax_region);
 526 }
 527
 528 void dax_region_put(struct dax_region *dax_region)
 529 {
 530         kref_put(&dax_region->kref, dax_region_free);
 531 }
 532 EXPORT_SYMBOL_GPL(dax_region_put);
 533
 534 static void dax_region_unregister(void *region)
 535 {
 536         struct dax_region *dax_region = region;
 537
 538         sysfs_remove_groups(&dax_region->dev->kobj,
 539                         dax_region_attribute_groups);
 540         dax_region_put(dax_region);
 541 }
 542
 543 struct dax_region *alloc_dax_region(struct device *parent, int region_id,
 544                 struct range *range, int target_node, unsigned int align,
 545                 unsigned long flags)
 546 {
 547         struct dax_region *dax_region;
 548
 549         /*
 550          * The DAX core assumes that it can store its private data in
 551          * parent->driver_data. This WARN is a reminder / safeguard for
 552          * developers of device-dax drivers.
 553          */
 554         if (dev_get_drvdata(parent)) {
 555                 dev_WARN(parent, "dax core failed to setup private data\n");
 556                 return NULL;
 557         }
 558
 559         if (!IS_ALIGNED(range->start, align)
 560                         || !IS_ALIGNED(range_len(range), align))
 561                 return NULL;
 562
 563         dax_region = kzalloc(sizeof(*dax_region), GFP_KERNEL);
 564         if (!dax_region)
 565                 return NULL;
 566
 567         dev_set_drvdata(parent, dax_region);
 568         kref_init(&dax_region->kref);
 569         dax_region->id = region_id;
 570         dax_region->align = align;
 571         dax_region->dev = parent;
 572         dax_region->target_node = target_node;
 573         ida_init(&dax_region->ida);
 574         dax_region->res = (struct resource) {
 575                 .start = range->start,
 576                 .end = range->end,
 577                 .flags = IORESOURCE_MEM | flags,
 578         };
 579
 580         if (sysfs_create_groups(&parent->kobj, dax_region_attribute_groups)) {
 581                 kfree(dax_region);
 582                 return NULL;
 583         }
 584
 585         kref_get(&dax_region->kref);
 586         if (devm_add_action_or_reset(parent, dax_region_unregister, dax_region))
 587                 return NULL;
 588         return dax_region;
 589 }
 590 EXPORT_SYMBOL_GPL(alloc_dax_region);
 591
 592 static void dax_mapping_release(struct device *dev)
 593 {
 594         struct dax_mapping *mapping = to_dax_mapping(dev);
 595         struct dev_dax *dev_dax = to_dev_dax(dev->parent);
 596
 597         ida_free(&dev_dax->ida, mapping->id);
 598         kfree(mapping);
 599 }
 600
 601 static void unregister_dax_mapping(void *data)
 602 {
 603         struct device *dev = data;
 604         struct dax_mapping *mapping = to_dax_mapping(dev);
 605         struct dev_dax *dev_dax = to_dev_dax(dev->parent);
 606         struct dax_region *dax_region = dev_dax->region;
 607
 608         dev_dbg(dev, "%s\n", __func__);
 609
 610         device_lock_assert(dax_region->dev);
 611
 612         dev_dax->ranges[mapping->range_id].mapping = NULL;
 613         mapping->range_id = -1;
 614
 615         device_del(dev);
 616         put_device(dev);
 617 }
 618
 619 static struct dev_dax_range *get_dax_range(struct device *dev)
 620 {
 621         struct dax_mapping *mapping = to_dax_mapping(dev);
 622         struct dev_dax *dev_dax = to_dev_dax(dev->parent);
 623         struct dax_region *dax_region = dev_dax->region;
 624
 625         device_lock(dax_region->dev);
 626         if (mapping->range_id < 0) {
 627                 device_unlock(dax_region->dev);
 628                 return NULL;
 629         }
 630
 631         return &dev_dax->ranges[mapping->range_id];
 632 }
 633
 634 static void put_dax_range(struct dev_dax_range *dax_range)
 635 {
 636         struct dax_mapping *mapping = dax_range->mapping;
 637         struct dev_dax *dev_dax = to_dev_dax(mapping->dev.parent);
 638         struct dax_region *dax_region = dev_dax->region;
 639
 640         device_unlock(dax_region->dev);
 641 }
 642
 643 static ssize_t start_show(struct device *dev,
 644                 struct device_attribute *attr, char *buf)
 645 {
 646         struct dev_dax_range *dax_range;
 647         ssize_t rc;
 648
 649         dax_range = get_dax_range(dev);
 650         if (!dax_range)
 651                 return -ENXIO;
 652         rc = sprintf(buf, "%#llx\n", dax_range->range.start);
 653         put_dax_range(dax_range);
 654
 655         return rc;
 656 }
 657 static DEVICE_ATTR(start, 0400, start_show, NULL);
 658
 659 static ssize_t end_show(struct device *dev,
 660                 struct device_attribute *attr, char *buf)
 661 {
 662         struct dev_dax_range *dax_range;
 663         ssize_t rc;
 664
 665         dax_range = get_dax_range(dev);
 666         if (!dax_range)
 667                 return -ENXIO;
 668         rc = sprintf(buf, "%#llx\n", dax_range->range.end);
 669         put_dax_range(dax_range);
 670
 671         return rc;
 672 }
 673 static DEVICE_ATTR(end, 0400, end_show, NULL);
 674
 675 static ssize_t pgoff_show(struct device *dev,
 676                 struct device_attribute *attr, char *buf)
 677 {
 678         struct dev_dax_range *dax_range;
 679         ssize_t rc;
 680
 681         dax_range = get_dax_range(dev);
 682         if (!dax_range)
 683                 return -ENXIO;
 684         rc = sprintf(buf, "%#lx\n", dax_range->pgoff);
 685         put_dax_range(dax_range);
 686
 687         return rc;
 688 }
 689 static DEVICE_ATTR(page_offset, 0400, pgoff_show, NULL);
 690
 691 static struct attribute *dax_mapping_attributes[] = {
 692         &dev_attr_start.attr,
 693         &dev_attr_end.attr,
 694         &dev_attr_page_offset.attr,
 695         NULL,
 696 };
 697
 698 static const struct attribute_group dax_mapping_attribute_group = {
 699         .attrs = dax_mapping_attributes,
 700 };
 701
 702 static const struct attribute_group *dax_mapping_attribute_groups[] = {
 703         &dax_mapping_attribute_group,
 704         NULL,
 705 };
 706
 707 static struct device_type dax_mapping_type = {
 708         .release = dax_mapping_release,
 709         .groups = dax_mapping_attribute_groups,
 710 };
 711
 712 static int devm_register_dax_mapping(struct dev_dax *dev_dax, int range_id)
 713 {
 714         struct dax_region *dax_region = dev_dax->region;
 715         struct dax_mapping *mapping;
 716         struct device *dev;
 717         int rc;
 718
 719         device_lock_assert(dax_region->dev);
 720
 721         if (dev_WARN_ONCE(&dev_dax->dev, !dax_region->dev->driver,
 722                                 "region disabled\n"))
 723                 return -ENXIO;
 724
 725         mapping = kzalloc(sizeof(*mapping), GFP_KERNEL);
 726         if (!mapping)
 727                 return -ENOMEM;
 728         mapping->range_id = range_id;
 729         mapping->id = ida_alloc(&dev_dax->ida, GFP_KERNEL);
 730         if (mapping->id < 0) {
 731                 kfree(mapping);
 732                 return -ENOMEM;
 733         }
 734         dev_dax->ranges[range_id].mapping = mapping;
 735         dev = &mapping->dev;
 736         device_initialize(dev);
 737         dev->parent = &dev_dax->dev;
 738         dev->type = &dax_mapping_type;
 739         dev_set_name(dev, "mapping%d", mapping->id);
 740         rc = device_add(dev);
 741         if (rc) {
 742                 put_device(dev);
 743                 return rc;
 744         }
 745
 746         rc = devm_add_action_or_reset(dax_region->dev, unregister_dax_mapping,
 747                         dev);
 748         if (rc)
 749                 return rc;
 750         return 0;
 751 }
 752
 753 static int alloc_dev_dax_range(struct dev_dax *dev_dax, u64 start,
 754                 resource_size_t size)
 755 {
 756         struct dax_region *dax_region = dev_dax->region;
 757         struct resource *res = &dax_region->res;
 758         struct device *dev = &dev_dax->dev;
 759         struct dev_dax_range *ranges;
 760         unsigned long pgoff = 0;
 761         struct resource *alloc;
 762         int i, rc;
 763
 764         device_lock_assert(dax_region->dev);
 765
 766         /* handle the seed alloc special case */
 767         if (!size) {
 768                 if (dev_WARN_ONCE(dev, dev_dax->nr_range,
 769                                         "0-size allocation must be first\n"))
 770                         return -EBUSY;
 771                 /* nr_range == 0 is elsewhere special cased as 0-size device */
 772                 return 0;
 773         }
 774
 775         alloc = __request_region(res, start, size, dev_name(dev), 0);
 776         if (!alloc)
 777                 return -ENOMEM;
 778
 779         ranges = krealloc(dev_dax->ranges, sizeof(*ranges)
 780                         * (dev_dax->nr_range + 1), GFP_KERNEL);
 781         if (!ranges) {
 782                 __release_region(res, alloc->start, resource_size(alloc));
 783                 return -ENOMEM;
 784         }
 785
 786         for (i = 0; i < dev_dax->nr_range; i++)
 787                 pgoff += PHYS_PFN(range_len(&ranges[i].range));
 788         dev_dax->ranges = ranges;
 789         ranges[dev_dax->nr_range++] = (struct dev_dax_range) {
 790                 .pgoff = pgoff,
 791                 .range = {
 792                         .start = alloc->start,
 793                         .end = alloc->end,
 794                 },
 795         };
 796
 797         dev_dbg(dev, "alloc range[%d]: %pa:%pa\n", dev_dax->nr_range - 1,
 798                         &alloc->start, &alloc->end);
 799         /*
 800          * A dev_dax instance must be registered before mapping device
 801          * children can be added. Defer to devm_create_dev_dax() to add
 802          * the initial mapping device.
 803          */
 804         if (!device_is_registered(&dev_dax->dev))
 805                 return 0;
 806
 807         rc = devm_register_dax_mapping(dev_dax, dev_dax->nr_range - 1);
 808         if (rc)
 809                 trim_dev_dax_range(dev_dax);
 810
 811         return rc;
 812 }
 813
 814 static int adjust_dev_dax_range(struct dev_dax *dev_dax, struct resource *res, resource_size_t size)
 815 {
 816         int last_range = dev_dax->nr_range - 1;
 817         struct dev_dax_range *dax_range = &dev_dax->ranges[last_range];
 818         struct dax_region *dax_region = dev_dax->region;
 819         bool is_shrink = resource_size(res) > size;
 820         struct range *range = &dax_range->range;
 821         struct device *dev = &dev_dax->dev;
 822         int rc;
 823
 824         device_lock_assert(dax_region->dev);
 825
 826         if (dev_WARN_ONCE(dev, !size, "deletion is handled by dev_dax_shrink\n"))
 827                 return -EINVAL;
 828
 829         rc = adjust_resource(res, range->start, size);
 830         if (rc)
 831                 return rc;
 832
 833         *range = (struct range) {
 834                 .start = range->start,
 835                 .end = range->start + size - 1,
 836         };
 837
 838         dev_dbg(dev, "%s range[%d]: %#llx:%#llx\n", is_shrink ? "shrink" : "extend",
 839                         last_range, (unsigned long long) range->start,
 840                         (unsigned long long) range->end);
 841
 842         return 0;
 843 }
 844
 845 static ssize_t size_show(struct device *dev,
 846                 struct device_attribute *attr, char *buf)
 847 {
 848         struct dev_dax *dev_dax = to_dev_dax(dev);
 849         unsigned long long size;
 850
 851         device_lock(dev);
 852         size = dev_dax_size(dev_dax);
 853         device_unlock(dev);
 854
 855         return sprintf(buf, "%llu\n", size);
 856 }
 857
 858 static bool alloc_is_aligned(struct dev_dax *dev_dax, resource_size_t size)
 859 {
 860         /*
 861          * The minimum mapping granularity for a device instance is a
 862          * single subsection, unless the arch says otherwise.
 863          */
 864         return IS_ALIGNED(size, max_t(unsigned long, dev_dax->align, memremap_compat_align()));
 865 }
 866
 867 static int dev_dax_shrink(struct dev_dax *dev_dax, resource_size_t size)
 868 {
 869         resource_size_t to_shrink = dev_dax_size(dev_dax) - size;
 870         struct dax_region *dax_region = dev_dax->region;
 871         struct device *dev = &dev_dax->dev;
 872         int i;
 873
 874         for (i = dev_dax->nr_range - 1; i >= 0; i--) {
 875                 struct range *range = &dev_dax->ranges[i].range;
 876                 struct dax_mapping *mapping = dev_dax->ranges[i].mapping;
 877                 struct resource *adjust = NULL, *res;
 878                 resource_size_t shrink;
 879
 880                 shrink = min_t(u64, to_shrink, range_len(range));
 881                 if (shrink >= range_len(range)) {
 882                         devm_release_action(dax_region->dev,
 883                                         unregister_dax_mapping, &mapping->dev);
 884                         trim_dev_dax_range(dev_dax);
 885                         to_shrink -= shrink;
 886                         if (!to_shrink)
 887                                 break;
 888                         continue;
 889                 }
 890
 891                 for_each_dax_region_resource(dax_region, res)
 892                         if (strcmp(res->name, dev_name(dev)) == 0
 893                                         && res->start == range->start) {
 894                                 adjust = res;
 895                                 break;
 896                         }
 897
 898                 if (dev_WARN_ONCE(dev, !adjust || i != dev_dax->nr_range - 1,
 899                                         "failed to find matching resource\n"))
 900                         return -ENXIO;
 901                 return adjust_dev_dax_range(dev_dax, adjust, range_len(range)
 902                                 - shrink);
 903         }
 904         return 0;
 905 }
 906
 907 /*
 908  * Only allow adjustments that preserve the relative pgoff of existing
 909  * allocations. I.e. the dev_dax->ranges array is ordered by increasing pgoff.
 910  */
 911 static bool adjust_ok(struct dev_dax *dev_dax, struct resource *res)
 912 {
 913         struct dev_dax_range *last;
 914         int i;
 915
 916         if (dev_dax->nr_range == 0)
 917                 return false;
 918         if (strcmp(res->name, dev_name(&dev_dax->dev)) != 0)
 919                 return false;
 920         last = &dev_dax->ranges[dev_dax->nr_range - 1];
 921         if (last->range.start != res->start || last->range.end != res->end)
 922                 return false;
 923         for (i = 0; i < dev_dax->nr_range - 1; i++) {
 924                 struct dev_dax_range *dax_range = &dev_dax->ranges[i];
 925
 926                 if (dax_range->pgoff > last->pgoff)
 927                         return false;
 928         }
 929
 930         return true;
 931 }
 932
 933 static ssize_t dev_dax_resize(struct dax_region *dax_region,
 934                 struct dev_dax *dev_dax, resource_size_t size)
 935 {
 936         resource_size_t avail = dax_region_avail_size(dax_region), to_alloc;
 937         resource_size_t dev_size = dev_dax_size(dev_dax);
 938         struct resource *region_res = &dax_region->res;
 939         struct device *dev = &dev_dax->dev;
 940         struct resource *res, *first;
 941         resource_size_t alloc = 0;
 942         int rc;
 943
 944         if (dev->driver)
 945                 return -EBUSY;
 946         if (size == dev_size)
 947                 return 0;
 948         if (size > dev_size && size - dev_size > avail)
 949                 return -ENOSPC;
 950         if (size < dev_size)
 951                 return dev_dax_shrink(dev_dax, size);
 952
 953         to_alloc = size - dev_size;
 954         if (dev_WARN_ONCE(dev, !alloc_is_aligned(dev_dax, to_alloc),
 955                         "resize of %pa misaligned\n", &to_alloc))
 956                 return -ENXIO;
 957
 958         /*
 959          * Expand the device into the unused portion of the region. This
 960          * may involve adjusting the end of an existing resource, or
 961          * allocating a new resource.
 962          */
 963 retry:
 964         first = region_res->child;
 965         if (!first)
 966                 return alloc_dev_dax_range(dev_dax, dax_region->res.start, to_alloc);
 967
 968         rc = -ENOSPC;
 969         for (res = first; res; res = res->sibling) {
 970                 struct resource *next = res->sibling;
 971
 972                 /* space at the beginning of the region */
 973                 if (res == first && res->start > dax_region->res.start) {
 974                         alloc = min(res->start - dax_region->res.start, to_alloc);
 975                         rc = alloc_dev_dax_range(dev_dax, dax_region->res.start, alloc);
 976                         break;
 977                 }
 978
 979                 alloc = 0;
 980                 /* space between allocations */
 981                 if (next && next->start > res->end + 1)
 982                         alloc = min(next->start - (res->end + 1), to_alloc);
 983
 984                 /* space at the end of the region */
 985                 if (!alloc && !next && res->end < region_res->end)
 986                         alloc = min(region_res->end - res->end, to_alloc);
 987
 988                 if (!alloc)
 989                         continue;
 990
 991                 if (adjust_ok(dev_dax, res)) {
 992                         rc = adjust_dev_dax_range(dev_dax, res, resource_size(res) + alloc);
 993                         break;
 994                 }
 995                 rc = alloc_dev_dax_range(dev_dax, res->end + 1, alloc);
 996                 break;
 997         }
 998         if (rc)
 999                 return rc;
1000         to_alloc -= alloc;
1001         if (to_alloc)
1002                 goto retry;
1003         return 0;
1004 }
1005
1006 static ssize_t size_store(struct device *dev, struct device_attribute *attr,
1007                 const char *buf, size_t len)
1008 {
1009         ssize_t rc;
1010         unsigned long long val;
1011         struct dev_dax *dev_dax = to_dev_dax(dev);
1012         struct dax_region *dax_region = dev_dax->region;
1013
1014         rc = kstrtoull(buf, 0, &val);
1015         if (rc)
1016                 return rc;
1017
1018         if (!alloc_is_aligned(dev_dax, val)) {
1019                 dev_dbg(dev, "%s: size: %lld misaligned\n", __func__, val);
1020                 return -EINVAL;
1021         }
1022
1023         device_lock(dax_region->dev);
1024         if (!dax_region->dev->driver) {
1025                 device_unlock(dax_region->dev);
1026                 return -ENXIO;
1027         }
1028         device_lock(dev);
1029         rc = dev_dax_resize(dax_region, dev_dax, val);
1030         device_unlock(dev);
1031         device_unlock(dax_region->dev);
1032
1033         return rc == 0 ? len : rc;
1034 }
1035 static DEVICE_ATTR_RW(size);
1036
1037 static ssize_t range_parse(const char *opt, size_t len, struct range *range)
1038 {
1039         unsigned long long addr = 0;
1040         char *start, *end, *str;
1041         ssize_t rc = EINVAL;
1042
1043         str = kstrdup(opt, GFP_KERNEL);
1044         if (!str)
1045                 return rc;
1046
1047         end = str;
1048         start = strsep(&end, "-");
1049         if (!start || !end)
1050                 goto err;
1051
1052         rc = kstrtoull(start, 16, &addr);
1053         if (rc)
1054                 goto err;
1055         range->start = addr;
1056
1057         rc = kstrtoull(end, 16, &addr);
1058         if (rc)
1059                 goto err;
1060         range->end = addr;
1061
1062 err:
1063         kfree(str);
1064         return rc;
1065 }
1066
1067 static ssize_t mapping_store(struct device *dev, struct device_attribute *attr,
1068                 const char *buf, size_t len)
1069 {
1070         struct dev_dax *dev_dax = to_dev_dax(dev);
1071         struct dax_region *dax_region = dev_dax->region;
1072         size_t to_alloc;
1073         struct range r;
1074         ssize_t rc;
1075
1076         rc = range_parse(buf, len, &r);
1077         if (rc)
1078                 return rc;
1079
1080         rc = -ENXIO;
1081         device_lock(dax_region->dev);
1082         if (!dax_region->dev->driver) {
1083                 device_unlock(dax_region->dev);
1084                 return rc;
1085         }
1086         device_lock(dev);
1087
1088         to_alloc = range_len(&r);
1089         if (alloc_is_aligned(dev_dax, to_alloc))
1090                 rc = alloc_dev_dax_range(dev_dax, r.start, to_alloc);
1091         device_unlock(dev);
1092         device_unlock(dax_region->dev);
1093
1094         return rc == 0 ? len : rc;
1095 }
1096 static DEVICE_ATTR_WO(mapping);
1097
1098 static ssize_t align_show(struct device *dev,
1099                 struct device_attribute *attr, char *buf)
1100 {
1101         struct dev_dax *dev_dax = to_dev_dax(dev);
1102
1103         return sprintf(buf, "%d\n", dev_dax->align);
1104 }
1105
1106 static ssize_t dev_dax_validate_align(struct dev_dax *dev_dax)
1107 {
1108         struct device *dev = &dev_dax->dev;
1109         int i;
1110
1111         for (i = 0; i < dev_dax->nr_range; i++) {
1112                 size_t len = range_len(&dev_dax->ranges[i].range);
1113
1114                 if (!alloc_is_aligned(dev_dax, len)) {
1115                         dev_dbg(dev, "%s: align %u invalid for range %d\n",
1116                                 __func__, dev_dax->align, i);
1117                         return -EINVAL;
1118                 }
1119         }
1120
1121         return 0;
1122 }
1123
1124 static ssize_t align_store(struct device *dev, struct device_attribute *attr,
1125                 const char *buf, size_t len)
1126 {
1127         struct dev_dax *dev_dax = to_dev_dax(dev);
1128         struct dax_region *dax_region = dev_dax->region;
1129         unsigned long val, align_save;
1130         ssize_t rc;
1131
1132         rc = kstrtoul(buf, 0, &val);
1133         if (rc)
1134                 return -ENXIO;
1135
1136         if (!dax_align_valid(val))
1137                 return -EINVAL;
1138
1139         device_lock(dax_region->dev);
1140         if (!dax_region->dev->driver) {
1141                 device_unlock(dax_region->dev);
1142                 return -ENXIO;
1143         }
1144
1145         device_lock(dev);
1146         if (dev->driver) {
1147                 rc = -EBUSY;
1148                 goto out_unlock;
1149         }
1150
1151         align_save = dev_dax->align;
1152         dev_dax->align = val;
1153         rc = dev_dax_validate_align(dev_dax);
1154         if (rc)
1155                 dev_dax->align = align_save;
1156 out_unlock:
1157         device_unlock(dev);
1158         device_unlock(dax_region->dev);
1159         return rc == 0 ? len : rc;
1160 }
1161 static DEVICE_ATTR_RW(align);
1162
1163 static int dev_dax_target_node(struct dev_dax *dev_dax)
1164 {
1165         struct dax_region *dax_region = dev_dax->region;
1166
1167         return dax_region->target_node;
1168 }
1169
1170 static ssize_t target_node_show(struct device *dev,
1171                 struct device_attribute *attr, char *buf)
1172 {
1173         struct dev_dax *dev_dax = to_dev_dax(dev);
1174
1175         return sprintf(buf, "%d\n", dev_dax_target_node(dev_dax));
1176 }
1177 static DEVICE_ATTR_RO(target_node);
1178
1179 static ssize_t resource_show(struct device *dev,
1180                 struct device_attribute *attr, char *buf)
1181 {
1182         struct dev_dax *dev_dax = to_dev_dax(dev);
1183         struct dax_region *dax_region = dev_dax->region;
1184         unsigned long long start;
1185
1186         if (dev_dax->nr_range < 1)
1187                 start = dax_region->res.start;
1188         else
1189                 start = dev_dax->ranges[0].range.start;
1190
1191         return sprintf(buf, "%#llx\n", start);
1192 }
1193 static DEVICE_ATTR(resource, 0400, resource_show, NULL);
1194
1195 static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
1196                 char *buf)
1197 {
1198         /*
1199          * We only ever expect to handle device-dax instances, i.e. the
1200          * @type argument to MODULE_ALIAS_DAX_DEVICE() is always zero
1201          */
1202         return sprintf(buf, DAX_DEVICE_MODALIAS_FMT "\n", 0);
1203 }
1204 static DEVICE_ATTR_RO(modalias);
1205
1206 static ssize_t numa_node_show(struct device *dev,
1207                 struct device_attribute *attr, char *buf)
1208 {
1209         return sprintf(buf, "%d\n", dev_to_node(dev));
1210 }
1211 static DEVICE_ATTR_RO(numa_node);
1212
1213 static umode_t dev_dax_visible(struct kobject *kobj, struct attribute *a, int n)
1214 {
1215         struct device *dev = container_of(kobj, struct device, kobj);
1216         struct dev_dax *dev_dax = to_dev_dax(dev);
1217         struct dax_region *dax_region = dev_dax->region;
1218
1219         if (a == &dev_attr_target_node.attr && dev_dax_target_node(dev_dax) < 0)
1220                 return 0;
1221         if (a == &dev_attr_numa_node.attr && !IS_ENABLED(CONFIG_NUMA))
1222                 return 0;
1223         if (a == &dev_attr_mapping.attr && is_static(dax_region))
1224                 return 0;
1225         if ((a == &dev_attr_align.attr ||
1226              a == &dev_attr_size.attr) && is_static(dax_region))
1227                 return 0444;
1228         return a->mode;
1229 }
1230
1231 static struct attribute *dev_dax_attributes[] = {
1232         &dev_attr_modalias.attr,
1233         &dev_attr_size.attr,
1234         &dev_attr_mapping.attr,
1235         &dev_attr_target_node.attr,
1236         &dev_attr_align.attr,
1237         &dev_attr_resource.attr,
1238         &dev_attr_numa_node.attr,
1239         NULL,
1240 };
1241
1242 static const struct attribute_group dev_dax_attribute_group = {
1243         .attrs = dev_dax_attributes,
1244         .is_visible = dev_dax_visible,
1245 };
1246
1247 static const struct attribute_group *dax_attribute_groups[] = {
1248         &dev_dax_attribute_group,
1249         NULL,
1250 };
1251
1252 static void dev_dax_release(struct device *dev)
1253 {
1254         struct dev_dax *dev_dax = to_dev_dax(dev);
1255         struct dax_region *dax_region = dev_dax->region;
1256         struct dax_device *dax_dev = dev_dax->dax_dev;
1257
1258         put_dax(dax_dev);
1259         free_dev_dax_id(dev_dax);
1260         dax_region_put(dax_region);
1261         kfree(dev_dax->pgmap);
1262         kfree(dev_dax);
1263 }
1264
1265 static const struct device_type dev_dax_type = {
1266         .release = dev_dax_release,
1267         .groups = dax_attribute_groups,
1268 };
1269
1270 struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
1271 {
1272         struct dax_region *dax_region = data->dax_region;
1273         struct device *parent = dax_region->dev;
1274         struct dax_device *dax_dev;
1275         struct dev_dax *dev_dax;
1276         struct inode *inode;
1277         struct device *dev;
1278         int rc;
1279
1280         dev_dax = kzalloc(sizeof(*dev_dax), GFP_KERNEL);
1281         if (!dev_dax)
1282                 return ERR_PTR(-ENOMEM);
1283
1284         if (is_static(dax_region)) {
1285                 if (dev_WARN_ONCE(parent, data->id < 0,
1286                                 "dynamic id specified to static region\n")) {
1287                         rc = -EINVAL;
1288                         goto err_id;
1289                 }
1290
1291                 dev_dax->id = data->id;
1292         } else {
1293                 if (dev_WARN_ONCE(parent, data->id >= 0,
1294                                 "static id specified to dynamic region\n")) {
1295                         rc = -EINVAL;
1296                         goto err_id;
1297                 }
1298
1299                 rc = ida_alloc(&dax_region->ida, GFP_KERNEL);
1300                 if (rc < 0)
1301                         goto err_id;
1302                 dev_dax->id = rc;
1303         }
1304
1305         dev_dax->region = dax_region;
1306         dev = &dev_dax->dev;
1307         device_initialize(dev);
1308         dev_set_name(dev, "dax%d.%d", dax_region->id, dev_dax->id);
1309
1310         rc = alloc_dev_dax_range(dev_dax, dax_region->res.start, data->size);
1311         if (rc)
1312                 goto err_range;
1313
1314         if (data->pgmap) {
1315                 dev_WARN_ONCE(parent, !is_static(dax_region),
1316                         "custom dev_pagemap requires a static dax_region\n");
1317
1318                 dev_dax->pgmap = kmemdup(data->pgmap,
1319                                 sizeof(struct dev_pagemap), GFP_KERNEL);
1320                 if (!dev_dax->pgmap) {
1321                         rc = -ENOMEM;
1322                         goto err_pgmap;
1323                 }
1324         }
1325
1326         /*
1327          * No 'host' or dax_operations since there is no access to this
1328          * device outside of mmap of the resulting character device.
1329          */
1330         dax_dev = alloc_dax(dev_dax, NULL, NULL, DAXDEV_F_SYNC);
1331         if (IS_ERR(dax_dev)) {
1332                 rc = PTR_ERR(dax_dev);
1333                 goto err_alloc_dax;
1334         }
1335
1336         /* a device_dax instance is dead while the driver is not attached */
1337         kill_dax(dax_dev);
1338
1339         dev_dax->dax_dev = dax_dev;
1340         dev_dax->target_node = dax_region->target_node;
1341         dev_dax->align = dax_region->align;
1342         ida_init(&dev_dax->ida);
1343         kref_get(&dax_region->kref);
1344
1345         inode = dax_inode(dax_dev);
1346         dev->devt = inode->i_rdev;
1347         if (data->subsys == DEV_DAX_BUS)
1348                 dev->bus = &dax_bus_type;
1349         else
1350                 dev->class = dax_class;
1351         dev->parent = parent;
1352         dev->type = &dev_dax_type;
1353
1354         rc = device_add(dev);
1355         if (rc) {
1356                 kill_dev_dax(dev_dax);
1357                 put_device(dev);
1358                 return ERR_PTR(rc);
1359         }
1360
1361         rc = devm_add_action_or_reset(dax_region->dev, unregister_dev_dax, dev);
1362         if (rc)
1363                 return ERR_PTR(rc);
1364
1365         /* register mapping device for the initial allocation range */
1366         if (dev_dax->nr_range && range_len(&dev_dax->ranges[0].range)) {
1367                 rc = devm_register_dax_mapping(dev_dax, 0);
1368                 if (rc)
1369                         return ERR_PTR(rc);
1370         }
1371
1372         return dev_dax;
1373
1374 err_alloc_dax:
1375         kfree(dev_dax->pgmap);
1376 err_pgmap:
1377         free_dev_dax_ranges(dev_dax);
1378 err_range:
1379         free_dev_dax_id(dev_dax);
1380 err_id:
1381         kfree(dev_dax);
1382
1383         return ERR_PTR(rc);
1384 }
1385 EXPORT_SYMBOL_GPL(devm_create_dev_dax);
1386
1387 static int match_always_count;
1388
1389 int __dax_driver_register(struct dax_device_driver *dax_drv,
1390                 struct module *module, const char *mod_name)
1391 {
1392         struct device_driver *drv = &dax_drv->drv;
1393         int rc = 0;
1394
1395         INIT_LIST_HEAD(&dax_drv->ids);
1396         drv->owner = module;
1397         drv->name = mod_name;
1398         drv->mod_name = mod_name;
1399         drv->bus = &dax_bus_type;
1400
1401         /* there can only be one default driver */
1402         mutex_lock(&dax_bus_lock);
1403         match_always_count += dax_drv->match_always;
1404         if (match_always_count > 1) {
1405                 match_always_count--;
1406                 WARN_ON(1);
1407                 rc = -EINVAL;
1408         }
1409         mutex_unlock(&dax_bus_lock);
1410         if (rc)
1411                 return rc;
1412         return driver_register(drv);
1413 }
1414 EXPORT_SYMBOL_GPL(__dax_driver_register);
1415
1416 void dax_driver_unregister(struct dax_device_driver *dax_drv)
1417 {
1418         struct device_driver *drv = &dax_drv->drv;
1419         struct dax_id *dax_id, *_id;
1420
1421         mutex_lock(&dax_bus_lock);
1422         match_always_count -= dax_drv->match_always;
1423         list_for_each_entry_safe(dax_id, _id, &dax_drv->ids, list) {
1424                 list_del(&dax_id->list);
1425                 kfree(dax_id);
1426         }
1427         mutex_unlock(&dax_bus_lock);
1428         driver_unregister(drv);
1429 }
1430 EXPORT_SYMBOL_GPL(dax_driver_unregister);
1431
1432 int __init dax_bus_init(void)
1433 {
1434         int rc;
1435
1436         if (IS_ENABLED(CONFIG_DEV_DAX_PMEM_COMPAT)) {
1437                 dax_class = class_create(THIS_MODULE, "dax");
1438                 if (IS_ERR(dax_class))
1439                         return PTR_ERR(dax_class);
1440         }
1441
1442         rc = bus_register(&dax_bus_type);
1443         if (rc)
1444                 class_destroy(dax_class);
1445         return rc;
1446 }
1447
1448 void __exit dax_bus_exit(void)
1449 {
1450         bus_unregister(&dax_bus_type);
1451         class_destroy(dax_class);
1452 }