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         device_del(dev);
 402         free_dev_dax_ranges(dev_dax);
 403         put_device(dev);
 404 }
 405
 406 static void dax_region_free(struct kref *kref)
 407 {
 408         struct dax_region *dax_region;
 409
 410         dax_region = container_of(kref, struct dax_region, kref);
 411         kfree(dax_region);
 412 }
 413
 414 void dax_region_put(struct dax_region *dax_region)
 415 {
 416         kref_put(&dax_region->kref, dax_region_free);
 417 }
 418 EXPORT_SYMBOL_GPL(dax_region_put);
 419
 420 /* a return value >= 0 indicates this invocation invalidated the id */
 421 static int __free_dev_dax_id(struct dev_dax *dev_dax)
 422 {
 423         struct device *dev = &dev_dax->dev;
 424         struct dax_region *dax_region;
 425         int rc = dev_dax->id;
 426
 427         device_lock_assert(dev);
 428
 429         if (!dev_dax->dyn_id || dev_dax->id < 0)
 430                 return -1;
 431         dax_region = dev_dax->region;
 432         ida_free(&dax_region->ida, dev_dax->id);
 433         dax_region_put(dax_region);
 434         dev_dax->id = -1;
 435         return rc;
 436 }
 437
 438 static int free_dev_dax_id(struct dev_dax *dev_dax)
 439 {
 440         struct device *dev = &dev_dax->dev;
 441         int rc;
 442
 443         device_lock(dev);
 444         rc = __free_dev_dax_id(dev_dax);
 445         device_unlock(dev);
 446         return rc;
 447 }
 448
 449 static int alloc_dev_dax_id(struct dev_dax *dev_dax)
 450 {
 451         struct dax_region *dax_region = dev_dax->region;
 452         int id;
 453
 454         id = ida_alloc(&dax_region->ida, GFP_KERNEL);
 455         if (id < 0)
 456                 return id;
 457         kref_get(&dax_region->kref);
 458         dev_dax->dyn_id = true;
 459         dev_dax->id = id;
 460         return id;
 461 }
 462
 463 static ssize_t delete_store(struct device *dev, struct device_attribute *attr,
 464                 const char *buf, size_t len)
 465 {
 466         struct dax_region *dax_region = dev_get_drvdata(dev);
 467         struct dev_dax *dev_dax;
 468         struct device *victim;
 469         bool do_del = false;
 470         int rc;
 471
 472         if (is_static(dax_region))
 473                 return -EINVAL;
 474
 475         victim = device_find_child_by_name(dax_region->dev, buf);
 476         if (!victim)
 477                 return -ENXIO;
 478
 479         device_lock(dev);
 480         device_lock(victim);
 481         dev_dax = to_dev_dax(victim);
 482         if (victim->driver || dev_dax_size(dev_dax))
 483                 rc = -EBUSY;
 484         else {
 485                 /*
 486                  * Invalidate the device so it does not become active
 487                  * again, but always preserve device-id-0 so that
 488                  * /sys/bus/dax/ is guaranteed to be populated while any
 489                  * dax_region is registered.
 490                  */
 491                 if (dev_dax->id > 0) {
 492                         do_del = __free_dev_dax_id(dev_dax) >= 0;
 493                         rc = len;
 494                         if (dax_region->seed == victim)
 495                                 dax_region->seed = NULL;
 496                         if (dax_region->youngest == victim)
 497                                 dax_region->youngest = NULL;
 498                 } else
 499                         rc = -EBUSY;
 500         }
 501         device_unlock(victim);
 502
 503         /* won the race to invalidate the device, clean it up */
 504         if (do_del)
 505                 devm_release_action(dev, unregister_dev_dax, victim);
 506         device_unlock(dev);
 507         put_device(victim);
 508
 509         return rc;
 510 }
 511 static DEVICE_ATTR_WO(delete);
 512
 513 static umode_t dax_region_visible(struct kobject *kobj, struct attribute *a,
 514                 int n)
 515 {
 516         struct device *dev = container_of(kobj, struct device, kobj);
 517         struct dax_region *dax_region = dev_get_drvdata(dev);
 518
 519         if (is_static(dax_region))
 520                 if (a == &dev_attr_available_size.attr
 521                                 || a == &dev_attr_create.attr
 522                                 || a == &dev_attr_seed.attr
 523                                 || a == &dev_attr_delete.attr)
 524                         return 0;
 525         return a->mode;
 526 }
 527
 528 static struct attribute *dax_region_attributes[] = {
 529         &dev_attr_available_size.attr,
 530         &dev_attr_region_size.attr,
 531         &dev_attr_region_align.attr,
 532         &dev_attr_create.attr,
 533         &dev_attr_seed.attr,
 534         &dev_attr_delete.attr,
 535         &dev_attr_id.attr,
 536         NULL,
 537 };
 538
 539 static const struct attribute_group dax_region_attribute_group = {
 540         .name = "dax_region",
 541         .attrs = dax_region_attributes,
 542         .is_visible = dax_region_visible,
 543 };
 544
 545 static const struct attribute_group *dax_region_attribute_groups[] = {
 546         &dax_region_attribute_group,
 547         NULL,
 548 };
 549
 550 static void dax_region_unregister(void *region)
 551 {
 552         struct dax_region *dax_region = region;
 553
 554         sysfs_remove_groups(&dax_region->dev->kobj,
 555                         dax_region_attribute_groups);
 556         dax_region_put(dax_region);
 557 }
 558
 559 struct dax_region *alloc_dax_region(struct device *parent, int region_id,
 560                 struct range *range, int target_node, unsigned int align,
 561                 unsigned long flags)
 562 {
 563         struct dax_region *dax_region;
 564
 565         /*
 566          * The DAX core assumes that it can store its private data in
 567          * parent->driver_data. This WARN is a reminder / safeguard for
 568          * developers of device-dax drivers.
 569          */
 570         if (dev_get_drvdata(parent)) {
 571                 dev_WARN(parent, "dax core failed to setup private data\n");
 572                 return NULL;
 573         }
 574
 575         if (!IS_ALIGNED(range->start, align)
 576                         || !IS_ALIGNED(range_len(range), align))
 577                 return NULL;
 578
 579         dax_region = kzalloc(sizeof(*dax_region), GFP_KERNEL);
 580         if (!dax_region)
 581                 return NULL;
 582
 583         dev_set_drvdata(parent, dax_region);
 584         kref_init(&dax_region->kref);
 585         dax_region->id = region_id;
 586         dax_region->align = align;
 587         dax_region->dev = parent;
 588         dax_region->target_node = target_node;
 589         ida_init(&dax_region->ida);
 590         dax_region->res = (struct resource) {
 591                 .start = range->start,
 592                 .end = range->end,
 593                 .flags = IORESOURCE_MEM | flags,
 594         };
 595
 596         if (sysfs_create_groups(&parent->kobj, dax_region_attribute_groups)) {
 597                 kfree(dax_region);
 598                 return NULL;
 599         }
 600
 601         kref_get(&dax_region->kref);
 602         if (devm_add_action_or_reset(parent, dax_region_unregister, dax_region))
 603                 return NULL;
 604         return dax_region;
 605 }
 606 EXPORT_SYMBOL_GPL(alloc_dax_region);
 607
 608 static void dax_mapping_release(struct device *dev)
 609 {
 610         struct dax_mapping *mapping = to_dax_mapping(dev);
 611         struct device *parent = dev->parent;
 612         struct dev_dax *dev_dax = to_dev_dax(parent);
 613
 614         ida_free(&dev_dax->ida, mapping->id);
 615         kfree(mapping);
 616         put_device(parent);
 617 }
 618
 619 static void unregister_dax_mapping(void *data)
 620 {
 621         struct device *dev = data;
 622         struct dax_mapping *mapping = to_dax_mapping(dev);
 623         struct dev_dax *dev_dax = to_dev_dax(dev->parent);
 624         struct dax_region *dax_region = dev_dax->region;
 625
 626         dev_dbg(dev, "%s\n", __func__);
 627
 628         device_lock_assert(dax_region->dev);
 629
 630         dev_dax->ranges[mapping->range_id].mapping = NULL;
 631         mapping->range_id = -1;
 632
 633         device_del(dev);
 634         put_device(dev);
 635 }
 636
 637 static struct dev_dax_range *get_dax_range(struct device *dev)
 638 {
 639         struct dax_mapping *mapping = to_dax_mapping(dev);
 640         struct dev_dax *dev_dax = to_dev_dax(dev->parent);
 641         struct dax_region *dax_region = dev_dax->region;
 642
 643         device_lock(dax_region->dev);
 644         if (mapping->range_id < 0) {
 645                 device_unlock(dax_region->dev);
 646                 return NULL;
 647         }
 648
 649         return &dev_dax->ranges[mapping->range_id];
 650 }
 651
 652 static void put_dax_range(struct dev_dax_range *dax_range)
 653 {
 654         struct dax_mapping *mapping = dax_range->mapping;
 655         struct dev_dax *dev_dax = to_dev_dax(mapping->dev.parent);
 656         struct dax_region *dax_region = dev_dax->region;
 657
 658         device_unlock(dax_region->dev);
 659 }
 660
 661 static ssize_t start_show(struct device *dev,
 662                 struct device_attribute *attr, char *buf)
 663 {
 664         struct dev_dax_range *dax_range;
 665         ssize_t rc;
 666
 667         dax_range = get_dax_range(dev);
 668         if (!dax_range)
 669                 return -ENXIO;
 670         rc = sprintf(buf, "%#llx\n", dax_range->range.start);
 671         put_dax_range(dax_range);
 672
 673         return rc;
 674 }
 675 static DEVICE_ATTR(start, 0400, start_show, NULL);
 676
 677 static ssize_t end_show(struct device *dev,
 678                 struct device_attribute *attr, char *buf)
 679 {
 680         struct dev_dax_range *dax_range;
 681         ssize_t rc;
 682
 683         dax_range = get_dax_range(dev);
 684         if (!dax_range)
 685                 return -ENXIO;
 686         rc = sprintf(buf, "%#llx\n", dax_range->range.end);
 687         put_dax_range(dax_range);
 688
 689         return rc;
 690 }
 691 static DEVICE_ATTR(end, 0400, end_show, NULL);
 692
 693 static ssize_t pgoff_show(struct device *dev,
 694                 struct device_attribute *attr, char *buf)
 695 {
 696         struct dev_dax_range *dax_range;
 697         ssize_t rc;
 698
 699         dax_range = get_dax_range(dev);
 700         if (!dax_range)
 701                 return -ENXIO;
 702         rc = sprintf(buf, "%#lx\n", dax_range->pgoff);
 703         put_dax_range(dax_range);
 704
 705         return rc;
 706 }
 707 static DEVICE_ATTR(page_offset, 0400, pgoff_show, NULL);
 708
 709 static struct attribute *dax_mapping_attributes[] = {
 710         &dev_attr_start.attr,
 711         &dev_attr_end.attr,
 712         &dev_attr_page_offset.attr,
 713         NULL,
 714 };
 715
 716 static const struct attribute_group dax_mapping_attribute_group = {
 717         .attrs = dax_mapping_attributes,
 718 };
 719
 720 static const struct attribute_group *dax_mapping_attribute_groups[] = {
 721         &dax_mapping_attribute_group,
 722         NULL,
 723 };
 724
 725 static struct device_type dax_mapping_type = {
 726         .release = dax_mapping_release,
 727         .groups = dax_mapping_attribute_groups,
 728 };
 729
 730 static int devm_register_dax_mapping(struct dev_dax *dev_dax, int range_id)
 731 {
 732         struct dax_region *dax_region = dev_dax->region;
 733         struct dax_mapping *mapping;
 734         struct device *dev;
 735         int rc;
 736
 737         device_lock_assert(dax_region->dev);
 738
 739         if (dev_WARN_ONCE(&dev_dax->dev, !dax_region->dev->driver,
 740                                 "region disabled\n"))
 741                 return -ENXIO;
 742
 743         mapping = kzalloc(sizeof(*mapping), GFP_KERNEL);
 744         if (!mapping)
 745                 return -ENOMEM;
 746         mapping->range_id = range_id;
 747         mapping->id = ida_alloc(&dev_dax->ida, GFP_KERNEL);
 748         if (mapping->id < 0) {
 749                 kfree(mapping);
 750                 return -ENOMEM;
 751         }
 752         dev_dax->ranges[range_id].mapping = mapping;
 753         dev = &mapping->dev;
 754         device_initialize(dev);
 755         dev->parent = &dev_dax->dev;
 756         get_device(dev->parent);
 757         dev->type = &dax_mapping_type;
 758         dev_set_name(dev, "mapping%d", mapping->id);
 759         rc = device_add(dev);
 760         if (rc) {
 761                 put_device(dev);
 762                 return rc;
 763         }
 764
 765         rc = devm_add_action_or_reset(dax_region->dev, unregister_dax_mapping,
 766                         dev);
 767         if (rc)
 768                 return rc;
 769         return 0;
 770 }
 771
 772 static int alloc_dev_dax_range(struct dev_dax *dev_dax, u64 start,
 773                 resource_size_t size)
 774 {
 775         struct dax_region *dax_region = dev_dax->region;
 776         struct resource *res = &dax_region->res;
 777         struct device *dev = &dev_dax->dev;
 778         struct dev_dax_range *ranges;
 779         unsigned long pgoff = 0;
 780         struct resource *alloc;
 781         int i, rc;
 782
 783         device_lock_assert(dax_region->dev);
 784
 785         /* handle the seed alloc special case */
 786         if (!size) {
 787                 if (dev_WARN_ONCE(dev, dev_dax->nr_range,
 788                                         "0-size allocation must be first\n"))
 789                         return -EBUSY;
 790                 /* nr_range == 0 is elsewhere special cased as 0-size device */
 791                 return 0;
 792         }
 793
 794         ranges = krealloc(dev_dax->ranges, sizeof(*ranges)
 795                         * (dev_dax->nr_range + 1), GFP_KERNEL);
 796         if (!ranges)
 797                 return -ENOMEM;
 798
 799         alloc = __request_region(res, start, size, dev_name(dev), 0);
 800         if (!alloc) {
 801                 /*
 802                  * If this was an empty set of ranges nothing else
 803                  * will release @ranges, so do it now.
 804                  */
 805                 if (!dev_dax->nr_range) {
 806                         kfree(ranges);
 807                         ranges = NULL;
 808                 }
 809                 dev_dax->ranges = ranges;
 810                 return -ENOMEM;
 811         }
 812
 813         for (i = 0; i < dev_dax->nr_range; i++)
 814                 pgoff += PHYS_PFN(range_len(&ranges[i].range));
 815         dev_dax->ranges = ranges;
 816         ranges[dev_dax->nr_range++] = (struct dev_dax_range) {
 817                 .pgoff = pgoff,
 818                 .range = {
 819                         .start = alloc->start,
 820                         .end = alloc->end,
 821                 },
 822         };
 823
 824         dev_dbg(dev, "alloc range[%d]: %pa:%pa\n", dev_dax->nr_range - 1,
 825                         &alloc->start, &alloc->end);
 826         /*
 827          * A dev_dax instance must be registered before mapping device
 828          * children can be added. Defer to devm_create_dev_dax() to add
 829          * the initial mapping device.
 830          */
 831         if (!device_is_registered(&dev_dax->dev))
 832                 return 0;
 833
 834         rc = devm_register_dax_mapping(dev_dax, dev_dax->nr_range - 1);
 835         if (rc)
 836                 trim_dev_dax_range(dev_dax);
 837
 838         return rc;
 839 }
 840
 841 static int adjust_dev_dax_range(struct dev_dax *dev_dax, struct resource *res, resource_size_t size)
 842 {
 843         int last_range = dev_dax->nr_range - 1;
 844         struct dev_dax_range *dax_range = &dev_dax->ranges[last_range];
 845         struct dax_region *dax_region = dev_dax->region;
 846         bool is_shrink = resource_size(res) > size;
 847         struct range *range = &dax_range->range;
 848         struct device *dev = &dev_dax->dev;
 849         int rc;
 850
 851         device_lock_assert(dax_region->dev);
 852
 853         if (dev_WARN_ONCE(dev, !size, "deletion is handled by dev_dax_shrink\n"))
 854                 return -EINVAL;
 855
 856         rc = adjust_resource(res, range->start, size);
 857         if (rc)
 858                 return rc;
 859
 860         *range = (struct range) {
 861                 .start = range->start,
 862                 .end = range->start + size - 1,
 863         };
 864
 865         dev_dbg(dev, "%s range[%d]: %#llx:%#llx\n", is_shrink ? "shrink" : "extend",
 866                         last_range, (unsigned long long) range->start,
 867                         (unsigned long long) range->end);
 868
 869         return 0;
 870 }
 871
 872 static ssize_t size_show(struct device *dev,
 873                 struct device_attribute *attr, char *buf)
 874 {
 875         struct dev_dax *dev_dax = to_dev_dax(dev);
 876         unsigned long long size;
 877
 878         device_lock(dev);
 879         size = dev_dax_size(dev_dax);
 880         device_unlock(dev);
 881
 882         return sprintf(buf, "%llu\n", size);
 883 }
 884
 885 static bool alloc_is_aligned(struct dev_dax *dev_dax, resource_size_t size)
 886 {
 887         /*
 888          * The minimum mapping granularity for a device instance is a
 889          * single subsection, unless the arch says otherwise.
 890          */
 891         return IS_ALIGNED(size, max_t(unsigned long, dev_dax->align, memremap_compat_align()));
 892 }
 893
 894 static int dev_dax_shrink(struct dev_dax *dev_dax, resource_size_t size)
 895 {
 896         resource_size_t to_shrink = dev_dax_size(dev_dax) - size;
 897         struct dax_region *dax_region = dev_dax->region;
 898         struct device *dev = &dev_dax->dev;
 899         int i;
 900
 901         for (i = dev_dax->nr_range - 1; i >= 0; i--) {
 902                 struct range *range = &dev_dax->ranges[i].range;
 903                 struct dax_mapping *mapping = dev_dax->ranges[i].mapping;
 904                 struct resource *adjust = NULL, *res;
 905                 resource_size_t shrink;
 906
 907                 shrink = min_t(u64, to_shrink, range_len(range));
 908                 if (shrink >= range_len(range)) {
 909                         devm_release_action(dax_region->dev,
 910                                         unregister_dax_mapping, &mapping->dev);
 911                         trim_dev_dax_range(dev_dax);
 912                         to_shrink -= shrink;
 913                         if (!to_shrink)
 914                                 break;
 915                         continue;
 916                 }
 917
 918                 for_each_dax_region_resource(dax_region, res)
 919                         if (strcmp(res->name, dev_name(dev)) == 0
 920                                         && res->start == range->start) {
 921                                 adjust = res;
 922                                 break;
 923                         }
 924
 925                 if (dev_WARN_ONCE(dev, !adjust || i != dev_dax->nr_range - 1,
 926                                         "failed to find matching resource\n"))
 927                         return -ENXIO;
 928                 return adjust_dev_dax_range(dev_dax, adjust, range_len(range)
 929                                 - shrink);
 930         }
 931         return 0;
 932 }
 933
 934 /*
 935  * Only allow adjustments that preserve the relative pgoff of existing
 936  * allocations. I.e. the dev_dax->ranges array is ordered by increasing pgoff.
 937  */
 938 static bool adjust_ok(struct dev_dax *dev_dax, struct resource *res)
 939 {
 940         struct dev_dax_range *last;
 941         int i;
 942
 943         if (dev_dax->nr_range == 0)
 944                 return false;
 945         if (strcmp(res->name, dev_name(&dev_dax->dev)) != 0)
 946                 return false;
 947         last = &dev_dax->ranges[dev_dax->nr_range - 1];
 948         if (last->range.start != res->start || last->range.end != res->end)
 949                 return false;
 950         for (i = 0; i < dev_dax->nr_range - 1; i++) {
 951                 struct dev_dax_range *dax_range = &dev_dax->ranges[i];
 952
 953                 if (dax_range->pgoff > last->pgoff)
 954                         return false;
 955         }
 956
 957         return true;
 958 }
 959
 960 static ssize_t dev_dax_resize(struct dax_region *dax_region,
 961                 struct dev_dax *dev_dax, resource_size_t size)
 962 {
 963         resource_size_t avail = dax_region_avail_size(dax_region), to_alloc;
 964         resource_size_t dev_size = dev_dax_size(dev_dax);
 965         struct resource *region_res = &dax_region->res;
 966         struct device *dev = &dev_dax->dev;
 967         struct resource *res, *first;
 968         resource_size_t alloc = 0;
 969         int rc;
 970
 971         if (dev->driver)
 972                 return -EBUSY;
 973         if (size == dev_size)
 974                 return 0;
 975         if (size > dev_size && size - dev_size > avail)
 976                 return -ENOSPC;
 977         if (size < dev_size)
 978                 return dev_dax_shrink(dev_dax, size);
 979
 980         to_alloc = size - dev_size;
 981         if (dev_WARN_ONCE(dev, !alloc_is_aligned(dev_dax, to_alloc),
 982                         "resize of %pa misaligned\n", &to_alloc))
 983                 return -ENXIO;
 984
 985         /*
 986          * Expand the device into the unused portion of the region. This
 987          * may involve adjusting the end of an existing resource, or
 988          * allocating a new resource.
 989          */
 990 retry:
 991         first = region_res->child;
 992         if (!first)
 993                 return alloc_dev_dax_range(dev_dax, dax_region->res.start, to_alloc);
 994
 995         rc = -ENOSPC;
 996         for (res = first; res; res = res->sibling) {
 997                 struct resource *next = res->sibling;
 998
 999                 /* space at the beginning of the region */
1000                 if (res == first && res->start > dax_region->res.start) {
1001                         alloc = min(res->start - dax_region->res.start, to_alloc);
1002                         rc = alloc_dev_dax_range(dev_dax, dax_region->res.start, alloc);
1003                         break;
1004                 }
1005
1006                 alloc = 0;
1007                 /* space between allocations */
1008                 if (next && next->start > res->end + 1)
1009                         alloc = min(next->start - (res->end + 1), to_alloc);
1010
1011                 /* space at the end of the region */
1012                 if (!alloc && !next && res->end < region_res->end)
1013                         alloc = min(region_res->end - res->end, to_alloc);
1014
1015                 if (!alloc)
1016                         continue;
1017
1018                 if (adjust_ok(dev_dax, res)) {
1019                         rc = adjust_dev_dax_range(dev_dax, res, resource_size(res) + alloc);
1020                         break;
1021                 }
1022                 rc = alloc_dev_dax_range(dev_dax, res->end + 1, alloc);
1023                 break;
1024         }
1025         if (rc)
1026                 return rc;
1027         to_alloc -= alloc;
1028         if (to_alloc)
1029                 goto retry;
1030         return 0;
1031 }
1032
1033 static ssize_t size_store(struct device *dev, struct device_attribute *attr,
1034                 const char *buf, size_t len)
1035 {
1036         ssize_t rc;
1037         unsigned long long val;
1038         struct dev_dax *dev_dax = to_dev_dax(dev);
1039         struct dax_region *dax_region = dev_dax->region;
1040
1041         rc = kstrtoull(buf, 0, &val);
1042         if (rc)
1043                 return rc;
1044
1045         if (!alloc_is_aligned(dev_dax, val)) {
1046                 dev_dbg(dev, "%s: size: %lld misaligned\n", __func__, val);
1047                 return -EINVAL;
1048         }
1049
1050         device_lock(dax_region->dev);
1051         if (!dax_region->dev->driver) {
1052                 device_unlock(dax_region->dev);
1053                 return -ENXIO;
1054         }
1055         device_lock(dev);
1056         rc = dev_dax_resize(dax_region, dev_dax, val);
1057         device_unlock(dev);
1058         device_unlock(dax_region->dev);
1059
1060         return rc == 0 ? len : rc;
1061 }
1062 static DEVICE_ATTR_RW(size);
1063
1064 static ssize_t range_parse(const char *opt, size_t len, struct range *range)
1065 {
1066         unsigned long long addr = 0;
1067         char *start, *end, *str;
1068         ssize_t rc = -EINVAL;
1069
1070         str = kstrdup(opt, GFP_KERNEL);
1071         if (!str)
1072                 return rc;
1073
1074         end = str;
1075         start = strsep(&end, "-");
1076         if (!start || !end)
1077                 goto err;
1078
1079         rc = kstrtoull(start, 16, &addr);
1080         if (rc)
1081                 goto err;
1082         range->start = addr;
1083
1084         rc = kstrtoull(end, 16, &addr);
1085         if (rc)
1086                 goto err;
1087         range->end = addr;
1088
1089 err:
1090         kfree(str);
1091         return rc;
1092 }
1093
1094 static ssize_t mapping_store(struct device *dev, struct device_attribute *attr,
1095                 const char *buf, size_t len)
1096 {
1097         struct dev_dax *dev_dax = to_dev_dax(dev);
1098         struct dax_region *dax_region = dev_dax->region;
1099         size_t to_alloc;
1100         struct range r;
1101         ssize_t rc;
1102
1103         rc = range_parse(buf, len, &r);
1104         if (rc)
1105                 return rc;
1106
1107         rc = -ENXIO;
1108         device_lock(dax_region->dev);
1109         if (!dax_region->dev->driver) {
1110                 device_unlock(dax_region->dev);
1111                 return rc;
1112         }
1113         device_lock(dev);
1114
1115         to_alloc = range_len(&r);
1116         if (alloc_is_aligned(dev_dax, to_alloc))
1117                 rc = alloc_dev_dax_range(dev_dax, r.start, to_alloc);
1118         device_unlock(dev);
1119         device_unlock(dax_region->dev);
1120
1121         return rc == 0 ? len : rc;
1122 }
1123 static DEVICE_ATTR_WO(mapping);
1124
1125 static ssize_t align_show(struct device *dev,
1126                 struct device_attribute *attr, char *buf)
1127 {
1128         struct dev_dax *dev_dax = to_dev_dax(dev);
1129
1130         return sprintf(buf, "%d\n", dev_dax->align);
1131 }
1132
1133 static ssize_t dev_dax_validate_align(struct dev_dax *dev_dax)
1134 {
1135         resource_size_t dev_size = dev_dax_size(dev_dax);
1136         struct device *dev = &dev_dax->dev;
1137         int i;
1138
1139         if (dev_size > 0 && !alloc_is_aligned(dev_dax, dev_size)) {
1140                 dev_dbg(dev, "%s: align %u invalid for size %pa\n",
1141                         __func__, dev_dax->align, &dev_size);
1142                 return -EINVAL;
1143         }
1144
1145         for (i = 0; i < dev_dax->nr_range; i++) {
1146                 size_t len = range_len(&dev_dax->ranges[i].range);
1147
1148                 if (!alloc_is_aligned(dev_dax, len)) {
1149                         dev_dbg(dev, "%s: align %u invalid for range %d\n",
1150                                 __func__, dev_dax->align, i);
1151                         return -EINVAL;
1152                 }
1153         }
1154
1155         return 0;
1156 }
1157
1158 static ssize_t align_store(struct device *dev, struct device_attribute *attr,
1159                 const char *buf, size_t len)
1160 {
1161         struct dev_dax *dev_dax = to_dev_dax(dev);
1162         struct dax_region *dax_region = dev_dax->region;
1163         unsigned long val, align_save;
1164         ssize_t rc;
1165
1166         rc = kstrtoul(buf, 0, &val);
1167         if (rc)
1168                 return -ENXIO;
1169
1170         if (!dax_align_valid(val))
1171                 return -EINVAL;
1172
1173         device_lock(dax_region->dev);
1174         if (!dax_region->dev->driver) {
1175                 device_unlock(dax_region->dev);
1176                 return -ENXIO;
1177         }
1178
1179         device_lock(dev);
1180         if (dev->driver) {
1181                 rc = -EBUSY;
1182                 goto out_unlock;
1183         }
1184
1185         align_save = dev_dax->align;
1186         dev_dax->align = val;
1187         rc = dev_dax_validate_align(dev_dax);
1188         if (rc)
1189                 dev_dax->align = align_save;
1190 out_unlock:
1191         device_unlock(dev);
1192         device_unlock(dax_region->dev);
1193         return rc == 0 ? len : rc;
1194 }
1195 static DEVICE_ATTR_RW(align);
1196
1197 static int dev_dax_target_node(struct dev_dax *dev_dax)
1198 {
1199         struct dax_region *dax_region = dev_dax->region;
1200
1201         return dax_region->target_node;
1202 }
1203
1204 static ssize_t target_node_show(struct device *dev,
1205                 struct device_attribute *attr, char *buf)
1206 {
1207         struct dev_dax *dev_dax = to_dev_dax(dev);
1208
1209         return sprintf(buf, "%d\n", dev_dax_target_node(dev_dax));
1210 }
1211 static DEVICE_ATTR_RO(target_node);
1212
1213 static ssize_t resource_show(struct device *dev,
1214                 struct device_attribute *attr, char *buf)
1215 {
1216         struct dev_dax *dev_dax = to_dev_dax(dev);
1217         struct dax_region *dax_region = dev_dax->region;
1218         unsigned long long start;
1219
1220         if (dev_dax->nr_range < 1)
1221                 start = dax_region->res.start;
1222         else
1223                 start = dev_dax->ranges[0].range.start;
1224
1225         return sprintf(buf, "%#llx\n", start);
1226 }
1227 static DEVICE_ATTR(resource, 0400, resource_show, NULL);
1228
1229 static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
1230                 char *buf)
1231 {
1232         /*
1233          * We only ever expect to handle device-dax instances, i.e. the
1234          * @type argument to MODULE_ALIAS_DAX_DEVICE() is always zero
1235          */
1236         return sprintf(buf, DAX_DEVICE_MODALIAS_FMT "\n", 0);
1237 }
1238 static DEVICE_ATTR_RO(modalias);
1239
1240 static ssize_t numa_node_show(struct device *dev,
1241                 struct device_attribute *attr, char *buf)
1242 {
1243         return sprintf(buf, "%d\n", dev_to_node(dev));
1244 }
1245 static DEVICE_ATTR_RO(numa_node);
1246
1247 static umode_t dev_dax_visible(struct kobject *kobj, struct attribute *a, int n)
1248 {
1249         struct device *dev = container_of(kobj, struct device, kobj);
1250         struct dev_dax *dev_dax = to_dev_dax(dev);
1251         struct dax_region *dax_region = dev_dax->region;
1252
1253         if (a == &dev_attr_target_node.attr && dev_dax_target_node(dev_dax) < 0)
1254                 return 0;
1255         if (a == &dev_attr_numa_node.attr && !IS_ENABLED(CONFIG_NUMA))
1256                 return 0;
1257         if (a == &dev_attr_mapping.attr && is_static(dax_region))
1258                 return 0;
1259         if ((a == &dev_attr_align.attr ||
1260              a == &dev_attr_size.attr) && is_static(dax_region))
1261                 return 0444;
1262         return a->mode;
1263 }
1264
1265 static struct attribute *dev_dax_attributes[] = {
1266         &dev_attr_modalias.attr,
1267         &dev_attr_size.attr,
1268         &dev_attr_mapping.attr,
1269         &dev_attr_target_node.attr,
1270         &dev_attr_align.attr,
1271         &dev_attr_resource.attr,
1272         &dev_attr_numa_node.attr,
1273         NULL,
1274 };
1275
1276 static const struct attribute_group dev_dax_attribute_group = {
1277         .attrs = dev_dax_attributes,
1278         .is_visible = dev_dax_visible,
1279 };
1280
1281 static const struct attribute_group *dax_attribute_groups[] = {
1282         &dev_dax_attribute_group,
1283         NULL,
1284 };
1285
1286 static void dev_dax_release(struct device *dev)
1287 {
1288         struct dev_dax *dev_dax = to_dev_dax(dev);
1289         struct dax_device *dax_dev = dev_dax->dax_dev;
1290
1291         put_dax(dax_dev);
1292         free_dev_dax_id(dev_dax);
1293         kfree(dev_dax->pgmap);
1294         kfree(dev_dax);
1295 }
1296
1297 static const struct device_type dev_dax_type = {
1298         .release = dev_dax_release,
1299         .groups = dax_attribute_groups,
1300 };
1301
1302 struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
1303 {
1304         struct dax_region *dax_region = data->dax_region;
1305         struct device *parent = dax_region->dev;
1306         struct dax_device *dax_dev;
1307         struct dev_dax *dev_dax;
1308         struct inode *inode;
1309         struct device *dev;
1310         int rc;
1311
1312         dev_dax = kzalloc(sizeof(*dev_dax), GFP_KERNEL);
1313         if (!dev_dax)
1314                 return ERR_PTR(-ENOMEM);
1315
1316         dev_dax->region = dax_region;
1317         if (is_static(dax_region)) {
1318                 if (dev_WARN_ONCE(parent, data->id < 0,
1319                                 "dynamic id specified to static region\n")) {
1320                         rc = -EINVAL;
1321                         goto err_id;
1322                 }
1323
1324                 dev_dax->id = data->id;
1325         } else {
1326                 if (dev_WARN_ONCE(parent, data->id >= 0,
1327                                 "static id specified to dynamic region\n")) {
1328                         rc = -EINVAL;
1329                         goto err_id;
1330                 }
1331
1332                 rc = alloc_dev_dax_id(dev_dax);
1333                 if (rc < 0)
1334                         goto err_id;
1335         }
1336
1337         dev = &dev_dax->dev;
1338         device_initialize(dev);
1339         dev_set_name(dev, "dax%d.%d", dax_region->id, dev_dax->id);
1340
1341         rc = alloc_dev_dax_range(dev_dax, dax_region->res.start, data->size);
1342         if (rc)
1343                 goto err_range;
1344
1345         if (data->pgmap) {
1346                 dev_WARN_ONCE(parent, !is_static(dax_region),
1347                         "custom dev_pagemap requires a static dax_region\n");
1348
1349                 dev_dax->pgmap = kmemdup(data->pgmap,
1350                                 sizeof(struct dev_pagemap), GFP_KERNEL);
1351                 if (!dev_dax->pgmap) {
1352                         rc = -ENOMEM;
1353                         goto err_pgmap;
1354                 }
1355         }
1356
1357         /*
1358          * No 'host' or dax_operations since there is no access to this
1359          * device outside of mmap of the resulting character device.
1360          */
1361         dax_dev = alloc_dax(dev_dax, NULL, NULL, DAXDEV_F_SYNC);
1362         if (IS_ERR(dax_dev)) {
1363                 rc = PTR_ERR(dax_dev);
1364                 goto err_alloc_dax;
1365         }
1366
1367         /* a device_dax instance is dead while the driver is not attached */
1368         kill_dax(dax_dev);
1369
1370         dev_dax->dax_dev = dax_dev;
1371         dev_dax->target_node = dax_region->target_node;
1372         dev_dax->align = dax_region->align;
1373         ida_init(&dev_dax->ida);
1374
1375         inode = dax_inode(dax_dev);
1376         dev->devt = inode->i_rdev;
1377         if (data->subsys == DEV_DAX_BUS)
1378                 dev->bus = &dax_bus_type;
1379         else
1380                 dev->class = dax_class;
1381         dev->parent = parent;
1382         dev->type = &dev_dax_type;
1383
1384         rc = device_add(dev);
1385         if (rc) {
1386                 kill_dev_dax(dev_dax);
1387                 put_device(dev);
1388                 return ERR_PTR(rc);
1389         }
1390
1391         rc = devm_add_action_or_reset(dax_region->dev, unregister_dev_dax, dev);
1392         if (rc)
1393                 return ERR_PTR(rc);
1394
1395         /* register mapping device for the initial allocation range */
1396         if (dev_dax->nr_range && range_len(&dev_dax->ranges[0].range)) {
1397                 rc = devm_register_dax_mapping(dev_dax, 0);
1398                 if (rc)
1399                         return ERR_PTR(rc);
1400         }
1401
1402         return dev_dax;
1403
1404 err_alloc_dax:
1405         kfree(dev_dax->pgmap);
1406 err_pgmap:
1407         free_dev_dax_ranges(dev_dax);
1408 err_range:
1409         free_dev_dax_id(dev_dax);
1410 err_id:
1411         kfree(dev_dax);
1412
1413         return ERR_PTR(rc);
1414 }
1415 EXPORT_SYMBOL_GPL(devm_create_dev_dax);
1416
1417 static int match_always_count;
1418
1419 int __dax_driver_register(struct dax_device_driver *dax_drv,
1420                 struct module *module, const char *mod_name)
1421 {
1422         struct device_driver *drv = &dax_drv->drv;
1423         int rc = 0;
1424
1425         INIT_LIST_HEAD(&dax_drv->ids);
1426         drv->owner = module;
1427         drv->name = mod_name;
1428         drv->mod_name = mod_name;
1429         drv->bus = &dax_bus_type;
1430
1431         /* there can only be one default driver */
1432         mutex_lock(&dax_bus_lock);
1433         match_always_count += dax_drv->match_always;
1434         if (match_always_count > 1) {
1435                 match_always_count--;
1436                 WARN_ON(1);
1437                 rc = -EINVAL;
1438         }
1439         mutex_unlock(&dax_bus_lock);
1440         if (rc)
1441                 return rc;
1442         return driver_register(drv);
1443 }
1444 EXPORT_SYMBOL_GPL(__dax_driver_register);
1445
1446 void dax_driver_unregister(struct dax_device_driver *dax_drv)
1447 {
1448         struct device_driver *drv = &dax_drv->drv;
1449         struct dax_id *dax_id, *_id;
1450
1451         mutex_lock(&dax_bus_lock);
1452         match_always_count -= dax_drv->match_always;
1453         list_for_each_entry_safe(dax_id, _id, &dax_drv->ids, list) {
1454                 list_del(&dax_id->list);
1455                 kfree(dax_id);
1456         }
1457         mutex_unlock(&dax_bus_lock);
1458         driver_unregister(drv);
1459 }
1460 EXPORT_SYMBOL_GPL(dax_driver_unregister);
1461
1462 int __init dax_bus_init(void)
1463 {
1464         int rc;
1465
1466         if (IS_ENABLED(CONFIG_DEV_DAX_PMEM_COMPAT)) {
1467                 dax_class = class_create(THIS_MODULE, "dax");
1468                 if (IS_ERR(dax_class))
1469                         return PTR_ERR(dax_class);
1470         }
1471
1472         rc = bus_register(&dax_bus_type);
1473         if (rc)
1474                 class_destroy(dax_class);
1475         return rc;
1476 }
1477
1478 void __exit dax_bus_exit(void)
1479 {
1480         bus_unregister(&dax_bus_type);
1481         class_destroy(dax_class);
1482 }