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         ranges = krealloc(dev_dax->ranges, sizeof(*ranges)
 776                         * (dev_dax->nr_range + 1), GFP_KERNEL);
 777         if (!ranges)
 778                 return -ENOMEM;
 779
 780         alloc = __request_region(res, start, size, dev_name(dev), 0);
 781         if (!alloc) {
 782                 /*
 783                  * If this was an empty set of ranges nothing else
 784                  * will release @ranges, so do it now.
 785                  */
 786                 if (!dev_dax->nr_range) {
 787                         kfree(ranges);
 788                         ranges = NULL;
 789                 }
 790                 dev_dax->ranges = ranges;
 791                 return -ENOMEM;
 792         }
 793
 794         for (i = 0; i < dev_dax->nr_range; i++)
 795                 pgoff += PHYS_PFN(range_len(&ranges[i].range));
 796         dev_dax->ranges = ranges;
 797         ranges[dev_dax->nr_range++] = (struct dev_dax_range) {
 798                 .pgoff = pgoff,
 799                 .range = {
 800                         .start = alloc->start,
 801                         .end = alloc->end,
 802                 },
 803         };
 804
 805         dev_dbg(dev, "alloc range[%d]: %pa:%pa\n", dev_dax->nr_range - 1,
 806                         &alloc->start, &alloc->end);
 807         /*
 808          * A dev_dax instance must be registered before mapping device
 809          * children can be added. Defer to devm_create_dev_dax() to add
 810          * the initial mapping device.
 811          */
 812         if (!device_is_registered(&dev_dax->dev))
 813                 return 0;
 814
 815         rc = devm_register_dax_mapping(dev_dax, dev_dax->nr_range - 1);
 816         if (rc)
 817                 trim_dev_dax_range(dev_dax);
 818
 819         return rc;
 820 }
 821
 822 static int adjust_dev_dax_range(struct dev_dax *dev_dax, struct resource *res, resource_size_t size)
 823 {
 824         int last_range = dev_dax->nr_range - 1;
 825         struct dev_dax_range *dax_range = &dev_dax->ranges[last_range];
 826         struct dax_region *dax_region = dev_dax->region;
 827         bool is_shrink = resource_size(res) > size;
 828         struct range *range = &dax_range->range;
 829         struct device *dev = &dev_dax->dev;
 830         int rc;
 831
 832         device_lock_assert(dax_region->dev);
 833
 834         if (dev_WARN_ONCE(dev, !size, "deletion is handled by dev_dax_shrink\n"))
 835                 return -EINVAL;
 836
 837         rc = adjust_resource(res, range->start, size);
 838         if (rc)
 839                 return rc;
 840
 841         *range = (struct range) {
 842                 .start = range->start,
 843                 .end = range->start + size - 1,
 844         };
 845
 846         dev_dbg(dev, "%s range[%d]: %#llx:%#llx\n", is_shrink ? "shrink" : "extend",
 847                         last_range, (unsigned long long) range->start,
 848                         (unsigned long long) range->end);
 849
 850         return 0;
 851 }
 852
 853 static ssize_t size_show(struct device *dev,
 854                 struct device_attribute *attr, char *buf)
 855 {
 856         struct dev_dax *dev_dax = to_dev_dax(dev);
 857         unsigned long long size;
 858
 859         device_lock(dev);
 860         size = dev_dax_size(dev_dax);
 861         device_unlock(dev);
 862
 863         return sprintf(buf, "%llu\n", size);
 864 }
 865
 866 static bool alloc_is_aligned(struct dev_dax *dev_dax, resource_size_t size)
 867 {
 868         /*
 869          * The minimum mapping granularity for a device instance is a
 870          * single subsection, unless the arch says otherwise.
 871          */
 872         return IS_ALIGNED(size, max_t(unsigned long, dev_dax->align, memremap_compat_align()));
 873 }
 874
 875 static int dev_dax_shrink(struct dev_dax *dev_dax, resource_size_t size)
 876 {
 877         resource_size_t to_shrink = dev_dax_size(dev_dax) - size;
 878         struct dax_region *dax_region = dev_dax->region;
 879         struct device *dev = &dev_dax->dev;
 880         int i;
 881
 882         for (i = dev_dax->nr_range - 1; i >= 0; i--) {
 883                 struct range *range = &dev_dax->ranges[i].range;
 884                 struct dax_mapping *mapping = dev_dax->ranges[i].mapping;
 885                 struct resource *adjust = NULL, *res;
 886                 resource_size_t shrink;
 887
 888                 shrink = min_t(u64, to_shrink, range_len(range));
 889                 if (shrink >= range_len(range)) {
 890                         devm_release_action(dax_region->dev,
 891                                         unregister_dax_mapping, &mapping->dev);
 892                         trim_dev_dax_range(dev_dax);
 893                         to_shrink -= shrink;
 894                         if (!to_shrink)
 895                                 break;
 896                         continue;
 897                 }
 898
 899                 for_each_dax_region_resource(dax_region, res)
 900                         if (strcmp(res->name, dev_name(dev)) == 0
 901                                         && res->start == range->start) {
 902                                 adjust = res;
 903                                 break;
 904                         }
 905
 906                 if (dev_WARN_ONCE(dev, !adjust || i != dev_dax->nr_range - 1,
 907                                         "failed to find matching resource\n"))
 908                         return -ENXIO;
 909                 return adjust_dev_dax_range(dev_dax, adjust, range_len(range)
 910                                 - shrink);
 911         }
 912         return 0;
 913 }
 914
 915 /*
 916  * Only allow adjustments that preserve the relative pgoff of existing
 917  * allocations. I.e. the dev_dax->ranges array is ordered by increasing pgoff.
 918  */
 919 static bool adjust_ok(struct dev_dax *dev_dax, struct resource *res)
 920 {
 921         struct dev_dax_range *last;
 922         int i;
 923
 924         if (dev_dax->nr_range == 0)
 925                 return false;
 926         if (strcmp(res->name, dev_name(&dev_dax->dev)) != 0)
 927                 return false;
 928         last = &dev_dax->ranges[dev_dax->nr_range - 1];
 929         if (last->range.start != res->start || last->range.end != res->end)
 930                 return false;
 931         for (i = 0; i < dev_dax->nr_range - 1; i++) {
 932                 struct dev_dax_range *dax_range = &dev_dax->ranges[i];
 933
 934                 if (dax_range->pgoff > last->pgoff)
 935                         return false;
 936         }
 937
 938         return true;
 939 }
 940
 941 static ssize_t dev_dax_resize(struct dax_region *dax_region,
 942                 struct dev_dax *dev_dax, resource_size_t size)
 943 {
 944         resource_size_t avail = dax_region_avail_size(dax_region), to_alloc;
 945         resource_size_t dev_size = dev_dax_size(dev_dax);
 946         struct resource *region_res = &dax_region->res;
 947         struct device *dev = &dev_dax->dev;
 948         struct resource *res, *first;
 949         resource_size_t alloc = 0;
 950         int rc;
 951
 952         if (dev->driver)
 953                 return -EBUSY;
 954         if (size == dev_size)
 955                 return 0;
 956         if (size > dev_size && size - dev_size > avail)
 957                 return -ENOSPC;
 958         if (size < dev_size)
 959                 return dev_dax_shrink(dev_dax, size);
 960
 961         to_alloc = size - dev_size;
 962         if (dev_WARN_ONCE(dev, !alloc_is_aligned(dev_dax, to_alloc),
 963                         "resize of %pa misaligned\n", &to_alloc))
 964                 return -ENXIO;
 965
 966         /*
 967          * Expand the device into the unused portion of the region. This
 968          * may involve adjusting the end of an existing resource, or
 969          * allocating a new resource.
 970          */
 971 retry:
 972         first = region_res->child;
 973         if (!first)
 974                 return alloc_dev_dax_range(dev_dax, dax_region->res.start, to_alloc);
 975
 976         rc = -ENOSPC;
 977         for (res = first; res; res = res->sibling) {
 978                 struct resource *next = res->sibling;
 979
 980                 /* space at the beginning of the region */
 981                 if (res == first && res->start > dax_region->res.start) {
 982                         alloc = min(res->start - dax_region->res.start, to_alloc);
 983                         rc = alloc_dev_dax_range(dev_dax, dax_region->res.start, alloc);
 984                         break;
 985                 }
 986
 987                 alloc = 0;
 988                 /* space between allocations */
 989                 if (next && next->start > res->end + 1)
 990                         alloc = min(next->start - (res->end + 1), to_alloc);
 991
 992                 /* space at the end of the region */
 993                 if (!alloc && !next && res->end < region_res->end)
 994                         alloc = min(region_res->end - res->end, to_alloc);
 995
 996                 if (!alloc)
 997                         continue;
 998
 999                 if (adjust_ok(dev_dax, res)) {
1000                         rc = adjust_dev_dax_range(dev_dax, res, resource_size(res) + alloc);
1001                         break;
1002                 }
1003                 rc = alloc_dev_dax_range(dev_dax, res->end + 1, alloc);
1004                 break;
1005         }
1006         if (rc)
1007                 return rc;
1008         to_alloc -= alloc;
1009         if (to_alloc)
1010                 goto retry;
1011         return 0;
1012 }
1013
1014 static ssize_t size_store(struct device *dev, struct device_attribute *attr,
1015                 const char *buf, size_t len)
1016 {
1017         ssize_t rc;
1018         unsigned long long val;
1019         struct dev_dax *dev_dax = to_dev_dax(dev);
1020         struct dax_region *dax_region = dev_dax->region;
1021
1022         rc = kstrtoull(buf, 0, &val);
1023         if (rc)
1024                 return rc;
1025
1026         if (!alloc_is_aligned(dev_dax, val)) {
1027                 dev_dbg(dev, "%s: size: %lld misaligned\n", __func__, val);
1028                 return -EINVAL;
1029         }
1030
1031         device_lock(dax_region->dev);
1032         if (!dax_region->dev->driver) {
1033                 device_unlock(dax_region->dev);
1034                 return -ENXIO;
1035         }
1036         device_lock(dev);
1037         rc = dev_dax_resize(dax_region, dev_dax, val);
1038         device_unlock(dev);
1039         device_unlock(dax_region->dev);
1040
1041         return rc == 0 ? len : rc;
1042 }
1043 static DEVICE_ATTR_RW(size);
1044
1045 static ssize_t range_parse(const char *opt, size_t len, struct range *range)
1046 {
1047         unsigned long long addr = 0;
1048         char *start, *end, *str;
1049         ssize_t rc = EINVAL;
1050
1051         str = kstrdup(opt, GFP_KERNEL);
1052         if (!str)
1053                 return rc;
1054
1055         end = str;
1056         start = strsep(&end, "-");
1057         if (!start || !end)
1058                 goto err;
1059
1060         rc = kstrtoull(start, 16, &addr);
1061         if (rc)
1062                 goto err;
1063         range->start = addr;
1064
1065         rc = kstrtoull(end, 16, &addr);
1066         if (rc)
1067                 goto err;
1068         range->end = addr;
1069
1070 err:
1071         kfree(str);
1072         return rc;
1073 }
1074
1075 static ssize_t mapping_store(struct device *dev, struct device_attribute *attr,
1076                 const char *buf, size_t len)
1077 {
1078         struct dev_dax *dev_dax = to_dev_dax(dev);
1079         struct dax_region *dax_region = dev_dax->region;
1080         size_t to_alloc;
1081         struct range r;
1082         ssize_t rc;
1083
1084         rc = range_parse(buf, len, &r);
1085         if (rc)
1086                 return rc;
1087
1088         rc = -ENXIO;
1089         device_lock(dax_region->dev);
1090         if (!dax_region->dev->driver) {
1091                 device_unlock(dax_region->dev);
1092                 return rc;
1093         }
1094         device_lock(dev);
1095
1096         to_alloc = range_len(&r);
1097         if (alloc_is_aligned(dev_dax, to_alloc))
1098                 rc = alloc_dev_dax_range(dev_dax, r.start, to_alloc);
1099         device_unlock(dev);
1100         device_unlock(dax_region->dev);
1101
1102         return rc == 0 ? len : rc;
1103 }
1104 static DEVICE_ATTR_WO(mapping);
1105
1106 static ssize_t align_show(struct device *dev,
1107                 struct device_attribute *attr, char *buf)
1108 {
1109         struct dev_dax *dev_dax = to_dev_dax(dev);
1110
1111         return sprintf(buf, "%d\n", dev_dax->align);
1112 }
1113
1114 static ssize_t dev_dax_validate_align(struct dev_dax *dev_dax)
1115 {
1116         struct device *dev = &dev_dax->dev;
1117         int i;
1118
1119         for (i = 0; i < dev_dax->nr_range; i++) {
1120                 size_t len = range_len(&dev_dax->ranges[i].range);
1121
1122                 if (!alloc_is_aligned(dev_dax, len)) {
1123                         dev_dbg(dev, "%s: align %u invalid for range %d\n",
1124                                 __func__, dev_dax->align, i);
1125                         return -EINVAL;
1126                 }
1127         }
1128
1129         return 0;
1130 }
1131
1132 static ssize_t align_store(struct device *dev, struct device_attribute *attr,
1133                 const char *buf, size_t len)
1134 {
1135         struct dev_dax *dev_dax = to_dev_dax(dev);
1136         struct dax_region *dax_region = dev_dax->region;
1137         unsigned long val, align_save;
1138         ssize_t rc;
1139
1140         rc = kstrtoul(buf, 0, &val);
1141         if (rc)
1142                 return -ENXIO;
1143
1144         if (!dax_align_valid(val))
1145                 return -EINVAL;
1146
1147         device_lock(dax_region->dev);
1148         if (!dax_region->dev->driver) {
1149                 device_unlock(dax_region->dev);
1150                 return -ENXIO;
1151         }
1152
1153         device_lock(dev);
1154         if (dev->driver) {
1155                 rc = -EBUSY;
1156                 goto out_unlock;
1157         }
1158
1159         align_save = dev_dax->align;
1160         dev_dax->align = val;
1161         rc = dev_dax_validate_align(dev_dax);
1162         if (rc)
1163                 dev_dax->align = align_save;
1164 out_unlock:
1165         device_unlock(dev);
1166         device_unlock(dax_region->dev);
1167         return rc == 0 ? len : rc;
1168 }
1169 static DEVICE_ATTR_RW(align);
1170
1171 static int dev_dax_target_node(struct dev_dax *dev_dax)
1172 {
1173         struct dax_region *dax_region = dev_dax->region;
1174
1175         return dax_region->target_node;
1176 }
1177
1178 static ssize_t target_node_show(struct device *dev,
1179                 struct device_attribute *attr, char *buf)
1180 {
1181         struct dev_dax *dev_dax = to_dev_dax(dev);
1182
1183         return sprintf(buf, "%d\n", dev_dax_target_node(dev_dax));
1184 }
1185 static DEVICE_ATTR_RO(target_node);
1186
1187 static ssize_t resource_show(struct device *dev,
1188                 struct device_attribute *attr, char *buf)
1189 {
1190         struct dev_dax *dev_dax = to_dev_dax(dev);
1191         struct dax_region *dax_region = dev_dax->region;
1192         unsigned long long start;
1193
1194         if (dev_dax->nr_range < 1)
1195                 start = dax_region->res.start;
1196         else
1197                 start = dev_dax->ranges[0].range.start;
1198
1199         return sprintf(buf, "%#llx\n", start);
1200 }
1201 static DEVICE_ATTR(resource, 0400, resource_show, NULL);
1202
1203 static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
1204                 char *buf)
1205 {
1206         /*
1207          * We only ever expect to handle device-dax instances, i.e. the
1208          * @type argument to MODULE_ALIAS_DAX_DEVICE() is always zero
1209          */
1210         return sprintf(buf, DAX_DEVICE_MODALIAS_FMT "\n", 0);
1211 }
1212 static DEVICE_ATTR_RO(modalias);
1213
1214 static ssize_t numa_node_show(struct device *dev,
1215                 struct device_attribute *attr, char *buf)
1216 {
1217         return sprintf(buf, "%d\n", dev_to_node(dev));
1218 }
1219 static DEVICE_ATTR_RO(numa_node);
1220
1221 static umode_t dev_dax_visible(struct kobject *kobj, struct attribute *a, int n)
1222 {
1223         struct device *dev = container_of(kobj, struct device, kobj);
1224         struct dev_dax *dev_dax = to_dev_dax(dev);
1225         struct dax_region *dax_region = dev_dax->region;
1226
1227         if (a == &dev_attr_target_node.attr && dev_dax_target_node(dev_dax) < 0)
1228                 return 0;
1229         if (a == &dev_attr_numa_node.attr && !IS_ENABLED(CONFIG_NUMA))
1230                 return 0;
1231         if (a == &dev_attr_mapping.attr && is_static(dax_region))
1232                 return 0;
1233         if ((a == &dev_attr_align.attr ||
1234              a == &dev_attr_size.attr) && is_static(dax_region))
1235                 return 0444;
1236         return a->mode;
1237 }
1238
1239 static struct attribute *dev_dax_attributes[] = {
1240         &dev_attr_modalias.attr,
1241         &dev_attr_size.attr,
1242         &dev_attr_mapping.attr,
1243         &dev_attr_target_node.attr,
1244         &dev_attr_align.attr,
1245         &dev_attr_resource.attr,
1246         &dev_attr_numa_node.attr,
1247         NULL,
1248 };
1249
1250 static const struct attribute_group dev_dax_attribute_group = {
1251         .attrs = dev_dax_attributes,
1252         .is_visible = dev_dax_visible,
1253 };
1254
1255 static const struct attribute_group *dax_attribute_groups[] = {
1256         &dev_dax_attribute_group,
1257         NULL,
1258 };
1259
1260 static void dev_dax_release(struct device *dev)
1261 {
1262         struct dev_dax *dev_dax = to_dev_dax(dev);
1263         struct dax_region *dax_region = dev_dax->region;
1264         struct dax_device *dax_dev = dev_dax->dax_dev;
1265
1266         put_dax(dax_dev);
1267         free_dev_dax_id(dev_dax);
1268         dax_region_put(dax_region);
1269         kfree(dev_dax->pgmap);
1270         kfree(dev_dax);
1271 }
1272
1273 static const struct device_type dev_dax_type = {
1274         .release = dev_dax_release,
1275         .groups = dax_attribute_groups,
1276 };
1277
1278 struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
1279 {
1280         struct dax_region *dax_region = data->dax_region;
1281         struct device *parent = dax_region->dev;
1282         struct dax_device *dax_dev;
1283         struct dev_dax *dev_dax;
1284         struct inode *inode;
1285         struct device *dev;
1286         int rc;
1287
1288         dev_dax = kzalloc(sizeof(*dev_dax), GFP_KERNEL);
1289         if (!dev_dax)
1290                 return ERR_PTR(-ENOMEM);
1291
1292         if (is_static(dax_region)) {
1293                 if (dev_WARN_ONCE(parent, data->id < 0,
1294                                 "dynamic id specified to static region\n")) {
1295                         rc = -EINVAL;
1296                         goto err_id;
1297                 }
1298
1299                 dev_dax->id = data->id;
1300         } else {
1301                 if (dev_WARN_ONCE(parent, data->id >= 0,
1302                                 "static id specified to dynamic region\n")) {
1303                         rc = -EINVAL;
1304                         goto err_id;
1305                 }
1306
1307                 rc = ida_alloc(&dax_region->ida, GFP_KERNEL);
1308                 if (rc < 0)
1309                         goto err_id;
1310                 dev_dax->id = rc;
1311         }
1312
1313         dev_dax->region = dax_region;
1314         dev = &dev_dax->dev;
1315         device_initialize(dev);
1316         dev_set_name(dev, "dax%d.%d", dax_region->id, dev_dax->id);
1317
1318         rc = alloc_dev_dax_range(dev_dax, dax_region->res.start, data->size);
1319         if (rc)
1320                 goto err_range;
1321
1322         if (data->pgmap) {
1323                 dev_WARN_ONCE(parent, !is_static(dax_region),
1324                         "custom dev_pagemap requires a static dax_region\n");
1325
1326                 dev_dax->pgmap = kmemdup(data->pgmap,
1327                                 sizeof(struct dev_pagemap), GFP_KERNEL);
1328                 if (!dev_dax->pgmap) {
1329                         rc = -ENOMEM;
1330                         goto err_pgmap;
1331                 }
1332         }
1333
1334         /*
1335          * No 'host' or dax_operations since there is no access to this
1336          * device outside of mmap of the resulting character device.
1337          */
1338         dax_dev = alloc_dax(dev_dax, NULL, NULL, DAXDEV_F_SYNC);
1339         if (IS_ERR(dax_dev)) {
1340                 rc = PTR_ERR(dax_dev);
1341                 goto err_alloc_dax;
1342         }
1343
1344         /* a device_dax instance is dead while the driver is not attached */
1345         kill_dax(dax_dev);
1346
1347         dev_dax->dax_dev = dax_dev;
1348         dev_dax->target_node = dax_region->target_node;
1349         dev_dax->align = dax_region->align;
1350         ida_init(&dev_dax->ida);
1351         kref_get(&dax_region->kref);
1352
1353         inode = dax_inode(dax_dev);
1354         dev->devt = inode->i_rdev;
1355         if (data->subsys == DEV_DAX_BUS)
1356                 dev->bus = &dax_bus_type;
1357         else
1358                 dev->class = dax_class;
1359         dev->parent = parent;
1360         dev->type = &dev_dax_type;
1361
1362         rc = device_add(dev);
1363         if (rc) {
1364                 kill_dev_dax(dev_dax);
1365                 put_device(dev);
1366                 return ERR_PTR(rc);
1367         }
1368
1369         rc = devm_add_action_or_reset(dax_region->dev, unregister_dev_dax, dev);
1370         if (rc)
1371                 return ERR_PTR(rc);
1372
1373         /* register mapping device for the initial allocation range */
1374         if (dev_dax->nr_range && range_len(&dev_dax->ranges[0].range)) {
1375                 rc = devm_register_dax_mapping(dev_dax, 0);
1376                 if (rc)
1377                         return ERR_PTR(rc);
1378         }
1379
1380         return dev_dax;
1381
1382 err_alloc_dax:
1383         kfree(dev_dax->pgmap);
1384 err_pgmap:
1385         free_dev_dax_ranges(dev_dax);
1386 err_range:
1387         free_dev_dax_id(dev_dax);
1388 err_id:
1389         kfree(dev_dax);
1390
1391         return ERR_PTR(rc);
1392 }
1393 EXPORT_SYMBOL_GPL(devm_create_dev_dax);
1394
1395 static int match_always_count;
1396
1397 int __dax_driver_register(struct dax_device_driver *dax_drv,
1398                 struct module *module, const char *mod_name)
1399 {
1400         struct device_driver *drv = &dax_drv->drv;
1401         int rc = 0;
1402
1403         INIT_LIST_HEAD(&dax_drv->ids);
1404         drv->owner = module;
1405         drv->name = mod_name;
1406         drv->mod_name = mod_name;
1407         drv->bus = &dax_bus_type;
1408
1409         /* there can only be one default driver */
1410         mutex_lock(&dax_bus_lock);
1411         match_always_count += dax_drv->match_always;
1412         if (match_always_count > 1) {
1413                 match_always_count--;
1414                 WARN_ON(1);
1415                 rc = -EINVAL;
1416         }
1417         mutex_unlock(&dax_bus_lock);
1418         if (rc)
1419                 return rc;
1420         return driver_register(drv);
1421 }
1422 EXPORT_SYMBOL_GPL(__dax_driver_register);
1423
1424 void dax_driver_unregister(struct dax_device_driver *dax_drv)
1425 {
1426         struct device_driver *drv = &dax_drv->drv;
1427         struct dax_id *dax_id, *_id;
1428
1429         mutex_lock(&dax_bus_lock);
1430         match_always_count -= dax_drv->match_always;
1431         list_for_each_entry_safe(dax_id, _id, &dax_drv->ids, list) {
1432                 list_del(&dax_id->list);
1433                 kfree(dax_id);
1434         }
1435         mutex_unlock(&dax_bus_lock);
1436         driver_unregister(drv);
1437 }
1438 EXPORT_SYMBOL_GPL(dax_driver_unregister);
1439
1440 int __init dax_bus_init(void)
1441 {
1442         int rc;
1443
1444         if (IS_ENABLED(CONFIG_DEV_DAX_PMEM_COMPAT)) {
1445                 dax_class = class_create(THIS_MODULE, "dax");
1446                 if (IS_ERR(dax_class))
1447                         return PTR_ERR(dax_class);
1448         }
1449
1450         rc = bus_register(&dax_bus_type);
1451         if (rc)
1452                 class_destroy(dax_class);
1453         return rc;
1454 }
1455
1456 void __exit dax_bus_exit(void)
1457 {
1458         bus_unregister(&dax_bus_type);
1459         class_destroy(dax_class);
1460 }