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         if (dax_drv->remove)
 183                 dax_drv->remove(dev_dax);
 184
 185         return 0;
 186 }
 187
 188 static struct bus_type dax_bus_type = {
 189         .name = "dax",
 190         .uevent = dax_bus_uevent,
 191         .match = dax_bus_match,
 192         .probe = dax_bus_probe,
 193         .remove = dax_bus_remove,
 194         .drv_groups = dax_drv_groups,
 195 };
 196
 197 static int dax_bus_match(struct device *dev, struct device_driver *drv)
 198 {
 199         struct dax_device_driver *dax_drv = to_dax_drv(drv);
 200
 201         /*
 202          * All but the 'device-dax' driver, which has 'match_always'
 203          * set, requires an exact id match.
 204          */
 205         if (dax_drv->match_always)
 206                 return 1;
 207
 208         return dax_match_id(dax_drv, dev);
 209 }
 210
 211 /*
 212  * Rely on the fact that drvdata is set before the attributes are
 213  * registered, and that the attributes are unregistered before drvdata
 214  * is cleared to assume that drvdata is always valid.
 215  */
 216 static ssize_t id_show(struct device *dev,
 217                 struct device_attribute *attr, char *buf)
 218 {
 219         struct dax_region *dax_region = dev_get_drvdata(dev);
 220
 221         return sprintf(buf, "%d\n", dax_region->id);
 222 }
 223 static DEVICE_ATTR_RO(id);
 224
 225 static ssize_t region_size_show(struct device *dev,
 226                 struct device_attribute *attr, char *buf)
 227 {
 228         struct dax_region *dax_region = dev_get_drvdata(dev);
 229
 230         return sprintf(buf, "%llu\n", (unsigned long long)
 231                         resource_size(&dax_region->res));
 232 }
 233 static struct device_attribute dev_attr_region_size = __ATTR(size, 0444,
 234                 region_size_show, NULL);
 235
 236 static ssize_t region_align_show(struct device *dev,
 237                 struct device_attribute *attr, char *buf)
 238 {
 239         struct dax_region *dax_region = dev_get_drvdata(dev);
 240
 241         return sprintf(buf, "%u\n", dax_region->align);
 242 }
 243 static struct device_attribute dev_attr_region_align =
 244                 __ATTR(align, 0400, region_align_show, NULL);
 245
 246 #define for_each_dax_region_resource(dax_region, res) \
 247         for (res = (dax_region)->res.child; res; res = res->sibling)
 248
 249 static unsigned long long dax_region_avail_size(struct dax_region *dax_region)
 250 {
 251         resource_size_t size = resource_size(&dax_region->res);
 252         struct resource *res;
 253
 254         device_lock_assert(dax_region->dev);
 255
 256         for_each_dax_region_resource(dax_region, res)
 257                 size -= resource_size(res);
 258         return size;
 259 }
 260
 261 static ssize_t available_size_show(struct device *dev,
 262                 struct device_attribute *attr, char *buf)
 263 {
 264         struct dax_region *dax_region = dev_get_drvdata(dev);
 265         unsigned long long size;
 266
 267         device_lock(dev);
 268         size = dax_region_avail_size(dax_region);
 269         device_unlock(dev);
 270
 271         return sprintf(buf, "%llu\n", size);
 272 }
 273 static DEVICE_ATTR_RO(available_size);
 274
 275 static ssize_t seed_show(struct device *dev,
 276                 struct device_attribute *attr, char *buf)
 277 {
 278         struct dax_region *dax_region = dev_get_drvdata(dev);
 279         struct device *seed;
 280         ssize_t rc;
 281
 282         if (is_static(dax_region))
 283                 return -EINVAL;
 284
 285         device_lock(dev);
 286         seed = dax_region->seed;
 287         rc = sprintf(buf, "%s\n", seed ? dev_name(seed) : "");
 288         device_unlock(dev);
 289
 290         return rc;
 291 }
 292 static DEVICE_ATTR_RO(seed);
 293
 294 static ssize_t create_show(struct device *dev,
 295                 struct device_attribute *attr, char *buf)
 296 {
 297         struct dax_region *dax_region = dev_get_drvdata(dev);
 298         struct device *youngest;
 299         ssize_t rc;
 300
 301         if (is_static(dax_region))
 302                 return -EINVAL;
 303
 304         device_lock(dev);
 305         youngest = dax_region->youngest;
 306         rc = sprintf(buf, "%s\n", youngest ? dev_name(youngest) : "");
 307         device_unlock(dev);
 308
 309         return rc;
 310 }
 311
 312 static ssize_t create_store(struct device *dev, struct device_attribute *attr,
 313                 const char *buf, size_t len)
 314 {
 315         struct dax_region *dax_region = dev_get_drvdata(dev);
 316         unsigned long long avail;
 317         ssize_t rc;
 318         int val;
 319
 320         if (is_static(dax_region))
 321                 return -EINVAL;
 322
 323         rc = kstrtoint(buf, 0, &val);
 324         if (rc)
 325                 return rc;
 326         if (val != 1)
 327                 return -EINVAL;
 328
 329         device_lock(dev);
 330         avail = dax_region_avail_size(dax_region);
 331         if (avail == 0)
 332                 rc = -ENOSPC;
 333         else {
 334                 struct dev_dax_data data = {
 335                         .dax_region = dax_region,
 336                         .size = 0,
 337                         .id = -1,
 338                 };
 339                 struct dev_dax *dev_dax = devm_create_dev_dax(&data);
 340
 341                 if (IS_ERR(dev_dax))
 342                         rc = PTR_ERR(dev_dax);
 343                 else {
 344                         /*
 345                          * In support of crafting multiple new devices
 346                          * simultaneously multiple seeds can be created,
 347                          * but only the first one that has not been
 348                          * successfully bound is tracked as the region
 349                          * seed.
 350                          */
 351                         if (!dax_region->seed)
 352                                 dax_region->seed = &dev_dax->dev;
 353                         dax_region->youngest = &dev_dax->dev;
 354                         rc = len;
 355                 }
 356         }
 357         device_unlock(dev);
 358
 359         return rc;
 360 }
 361 static DEVICE_ATTR_RW(create);
 362
 363 void kill_dev_dax(struct dev_dax *dev_dax)
 364 {
 365         struct dax_device *dax_dev = dev_dax->dax_dev;
 366         struct inode *inode = dax_inode(dax_dev);
 367
 368         kill_dax(dax_dev);
 369         unmap_mapping_range(inode->i_mapping, 0, 0, 1);
 370 }
 371 EXPORT_SYMBOL_GPL(kill_dev_dax);
 372
 373 static void trim_dev_dax_range(struct dev_dax *dev_dax)
 374 {
 375         int i = dev_dax->nr_range - 1;
 376         struct range *range = &dev_dax->ranges[i].range;
 377         struct dax_region *dax_region = dev_dax->region;
 378
 379         device_lock_assert(dax_region->dev);
 380         dev_dbg(&dev_dax->dev, "delete range[%d]: %#llx:%#llx\n", i,
 381                 (unsigned long long)range->start,
 382                 (unsigned long long)range->end);
 383
 384         __release_region(&dax_region->res, range->start, range_len(range));
 385         if (--dev_dax->nr_range == 0) {
 386                 kfree(dev_dax->ranges);
 387                 dev_dax->ranges = NULL;
 388         }
 389 }
 390
 391 static void free_dev_dax_ranges(struct dev_dax *dev_dax)
 392 {
 393         while (dev_dax->nr_range)
 394                 trim_dev_dax_range(dev_dax);
 395 }
 396
 397 static void unregister_dev_dax(void *dev)
 398 {
 399         struct dev_dax *dev_dax = to_dev_dax(dev);
 400
 401         dev_dbg(dev, "%s\n", __func__);
 402
 403         kill_dev_dax(dev_dax);
 404         free_dev_dax_ranges(dev_dax);
 405         device_del(dev);
 406         put_device(dev);
 407 }
 408
 409 /* a return value >= 0 indicates this invocation invalidated the id */
 410 static int __free_dev_dax_id(struct dev_dax *dev_dax)
 411 {
 412         struct dax_region *dax_region = dev_dax->region;
 413         struct device *dev = &dev_dax->dev;
 414         int rc = dev_dax->id;
 415
 416         device_lock_assert(dev);
 417
 418         if (is_static(dax_region) || dev_dax->id < 0)
 419                 return -1;
 420         ida_free(&dax_region->ida, dev_dax->id);
 421         dev_dax->id = -1;
 422         return rc;
 423 }
 424
 425 static int free_dev_dax_id(struct dev_dax *dev_dax)
 426 {
 427         struct device *dev = &dev_dax->dev;
 428         int rc;
 429
 430         device_lock(dev);
 431         rc = __free_dev_dax_id(dev_dax);
 432         device_unlock(dev);
 433         return rc;
 434 }
 435
 436 static ssize_t delete_store(struct device *dev, struct device_attribute *attr,
 437                 const char *buf, size_t len)
 438 {
 439         struct dax_region *dax_region = dev_get_drvdata(dev);
 440         struct dev_dax *dev_dax;
 441         struct device *victim;
 442         bool do_del = false;
 443         int rc;
 444
 445         if (is_static(dax_region))
 446                 return -EINVAL;
 447
 448         victim = device_find_child_by_name(dax_region->dev, buf);
 449         if (!victim)
 450                 return -ENXIO;
 451
 452         device_lock(dev);
 453         device_lock(victim);
 454         dev_dax = to_dev_dax(victim);
 455         if (victim->driver || dev_dax_size(dev_dax))
 456                 rc = -EBUSY;
 457         else {
 458                 /*
 459                  * Invalidate the device so it does not become active
 460                  * again, but always preserve device-id-0 so that
 461                  * /sys/bus/dax/ is guaranteed to be populated while any
 462                  * dax_region is registered.
 463                  */
 464                 if (dev_dax->id > 0) {
 465                         do_del = __free_dev_dax_id(dev_dax) >= 0;
 466                         rc = len;
 467                         if (dax_region->seed == victim)
 468                                 dax_region->seed = NULL;
 469                         if (dax_region->youngest == victim)
 470                                 dax_region->youngest = NULL;
 471                 } else
 472                         rc = -EBUSY;
 473         }
 474         device_unlock(victim);
 475
 476         /* won the race to invalidate the device, clean it up */
 477         if (do_del)
 478                 devm_release_action(dev, unregister_dev_dax, victim);
 479         device_unlock(dev);
 480         put_device(victim);
 481
 482         return rc;
 483 }
 484 static DEVICE_ATTR_WO(delete);
 485
 486 static umode_t dax_region_visible(struct kobject *kobj, struct attribute *a,
 487                 int n)
 488 {
 489         struct device *dev = container_of(kobj, struct device, kobj);
 490         struct dax_region *dax_region = dev_get_drvdata(dev);
 491
 492         if (is_static(dax_region))
 493                 if (a == &dev_attr_available_size.attr
 494                                 || a == &dev_attr_create.attr
 495                                 || a == &dev_attr_seed.attr
 496                                 || a == &dev_attr_delete.attr)
 497                         return 0;
 498         return a->mode;
 499 }
 500
 501 static struct attribute *dax_region_attributes[] = {
 502         &dev_attr_available_size.attr,
 503         &dev_attr_region_size.attr,
 504         &dev_attr_region_align.attr,
 505         &dev_attr_create.attr,
 506         &dev_attr_seed.attr,
 507         &dev_attr_delete.attr,
 508         &dev_attr_id.attr,
 509         NULL,
 510 };
 511
 512 static const struct attribute_group dax_region_attribute_group = {
 513         .name = "dax_region",
 514         .attrs = dax_region_attributes,
 515         .is_visible = dax_region_visible,
 516 };
 517
 518 static const struct attribute_group *dax_region_attribute_groups[] = {
 519         &dax_region_attribute_group,
 520         NULL,
 521 };
 522
 523 static void dax_region_free(struct kref *kref)
 524 {
 525         struct dax_region *dax_region;
 526
 527         dax_region = container_of(kref, struct dax_region, kref);
 528         kfree(dax_region);
 529 }
 530
 531 void dax_region_put(struct dax_region *dax_region)
 532 {
 533         kref_put(&dax_region->kref, dax_region_free);
 534 }
 535 EXPORT_SYMBOL_GPL(dax_region_put);
 536
 537 static void dax_region_unregister(void *region)
 538 {
 539         struct dax_region *dax_region = region;
 540
 541         sysfs_remove_groups(&dax_region->dev->kobj,
 542                         dax_region_attribute_groups);
 543         dax_region_put(dax_region);
 544 }
 545
 546 struct dax_region *alloc_dax_region(struct device *parent, int region_id,
 547                 struct range *range, int target_node, unsigned int align,
 548                 unsigned long flags)
 549 {
 550         struct dax_region *dax_region;
 551
 552         /*
 553          * The DAX core assumes that it can store its private data in
 554          * parent->driver_data. This WARN is a reminder / safeguard for
 555          * developers of device-dax drivers.
 556          */
 557         if (dev_get_drvdata(parent)) {
 558                 dev_WARN(parent, "dax core failed to setup private data\n");
 559                 return NULL;
 560         }
 561
 562         if (!IS_ALIGNED(range->start, align)
 563                         || !IS_ALIGNED(range_len(range), align))
 564                 return NULL;
 565
 566         dax_region = kzalloc(sizeof(*dax_region), GFP_KERNEL);
 567         if (!dax_region)
 568                 return NULL;
 569
 570         dev_set_drvdata(parent, dax_region);
 571         kref_init(&dax_region->kref);
 572         dax_region->id = region_id;
 573         dax_region->align = align;
 574         dax_region->dev = parent;
 575         dax_region->target_node = target_node;
 576         ida_init(&dax_region->ida);
 577         dax_region->res = (struct resource) {
 578                 .start = range->start,
 579                 .end = range->end,
 580                 .flags = IORESOURCE_MEM | flags,
 581         };
 582
 583         if (sysfs_create_groups(&parent->kobj, dax_region_attribute_groups)) {
 584                 kfree(dax_region);
 585                 return NULL;
 586         }
 587
 588         kref_get(&dax_region->kref);
 589         if (devm_add_action_or_reset(parent, dax_region_unregister, dax_region))
 590                 return NULL;
 591         return dax_region;
 592 }
 593 EXPORT_SYMBOL_GPL(alloc_dax_region);
 594
 595 static void dax_mapping_release(struct device *dev)
 596 {
 597         struct dax_mapping *mapping = to_dax_mapping(dev);
 598         struct dev_dax *dev_dax = to_dev_dax(dev->parent);
 599
 600         ida_free(&dev_dax->ida, mapping->id);
 601         kfree(mapping);
 602 }
 603
 604 static void unregister_dax_mapping(void *data)
 605 {
 606         struct device *dev = data;
 607         struct dax_mapping *mapping = to_dax_mapping(dev);
 608         struct dev_dax *dev_dax = to_dev_dax(dev->parent);
 609         struct dax_region *dax_region = dev_dax->region;
 610
 611         dev_dbg(dev, "%s\n", __func__);
 612
 613         device_lock_assert(dax_region->dev);
 614
 615         dev_dax->ranges[mapping->range_id].mapping = NULL;
 616         mapping->range_id = -1;
 617
 618         device_del(dev);
 619         put_device(dev);
 620 }
 621
 622 static struct dev_dax_range *get_dax_range(struct device *dev)
 623 {
 624         struct dax_mapping *mapping = to_dax_mapping(dev);
 625         struct dev_dax *dev_dax = to_dev_dax(dev->parent);
 626         struct dax_region *dax_region = dev_dax->region;
 627
 628         device_lock(dax_region->dev);
 629         if (mapping->range_id < 0) {
 630                 device_unlock(dax_region->dev);
 631                 return NULL;
 632         }
 633
 634         return &dev_dax->ranges[mapping->range_id];
 635 }
 636
 637 static void put_dax_range(struct dev_dax_range *dax_range)
 638 {
 639         struct dax_mapping *mapping = dax_range->mapping;
 640         struct dev_dax *dev_dax = to_dev_dax(mapping->dev.parent);
 641         struct dax_region *dax_region = dev_dax->region;
 642
 643         device_unlock(dax_region->dev);
 644 }
 645
 646 static ssize_t start_show(struct device *dev,
 647                 struct device_attribute *attr, char *buf)
 648 {
 649         struct dev_dax_range *dax_range;
 650         ssize_t rc;
 651
 652         dax_range = get_dax_range(dev);
 653         if (!dax_range)
 654                 return -ENXIO;
 655         rc = sprintf(buf, "%#llx\n", dax_range->range.start);
 656         put_dax_range(dax_range);
 657
 658         return rc;
 659 }
 660 static DEVICE_ATTR(start, 0400, start_show, NULL);
 661
 662 static ssize_t end_show(struct device *dev,
 663                 struct device_attribute *attr, char *buf)
 664 {
 665         struct dev_dax_range *dax_range;
 666         ssize_t rc;
 667
 668         dax_range = get_dax_range(dev);
 669         if (!dax_range)
 670                 return -ENXIO;
 671         rc = sprintf(buf, "%#llx\n", dax_range->range.end);
 672         put_dax_range(dax_range);
 673
 674         return rc;
 675 }
 676 static DEVICE_ATTR(end, 0400, end_show, NULL);
 677
 678 static ssize_t pgoff_show(struct device *dev,
 679                 struct device_attribute *attr, char *buf)
 680 {
 681         struct dev_dax_range *dax_range;
 682         ssize_t rc;
 683
 684         dax_range = get_dax_range(dev);
 685         if (!dax_range)
 686                 return -ENXIO;
 687         rc = sprintf(buf, "%#lx\n", dax_range->pgoff);
 688         put_dax_range(dax_range);
 689
 690         return rc;
 691 }
 692 static DEVICE_ATTR(page_offset, 0400, pgoff_show, NULL);
 693
 694 static struct attribute *dax_mapping_attributes[] = {
 695         &dev_attr_start.attr,
 696         &dev_attr_end.attr,
 697         &dev_attr_page_offset.attr,
 698         NULL,
 699 };
 700
 701 static const struct attribute_group dax_mapping_attribute_group = {
 702         .attrs = dax_mapping_attributes,
 703 };
 704
 705 static const struct attribute_group *dax_mapping_attribute_groups[] = {
 706         &dax_mapping_attribute_group,
 707         NULL,
 708 };
 709
 710 static struct device_type dax_mapping_type = {
 711         .release = dax_mapping_release,
 712         .groups = dax_mapping_attribute_groups,
 713 };
 714
 715 static int devm_register_dax_mapping(struct dev_dax *dev_dax, int range_id)
 716 {
 717         struct dax_region *dax_region = dev_dax->region;
 718         struct dax_mapping *mapping;
 719         struct device *dev;
 720         int rc;
 721
 722         device_lock_assert(dax_region->dev);
 723
 724         if (dev_WARN_ONCE(&dev_dax->dev, !dax_region->dev->driver,
 725                                 "region disabled\n"))
 726                 return -ENXIO;
 727
 728         mapping = kzalloc(sizeof(*mapping), GFP_KERNEL);
 729         if (!mapping)
 730                 return -ENOMEM;
 731         mapping->range_id = range_id;
 732         mapping->id = ida_alloc(&dev_dax->ida, GFP_KERNEL);
 733         if (mapping->id < 0) {
 734                 kfree(mapping);
 735                 return -ENOMEM;
 736         }
 737         dev_dax->ranges[range_id].mapping = mapping;
 738         dev = &mapping->dev;
 739         device_initialize(dev);
 740         dev->parent = &dev_dax->dev;
 741         dev->type = &dax_mapping_type;
 742         dev_set_name(dev, "mapping%d", mapping->id);
 743         rc = device_add(dev);
 744         if (rc) {
 745                 put_device(dev);
 746                 return rc;
 747         }
 748
 749         rc = devm_add_action_or_reset(dax_region->dev, unregister_dax_mapping,
 750                         dev);
 751         if (rc)
 752                 return rc;
 753         return 0;
 754 }
 755
 756 static int alloc_dev_dax_range(struct dev_dax *dev_dax, u64 start,
 757                 resource_size_t size)
 758 {
 759         struct dax_region *dax_region = dev_dax->region;
 760         struct resource *res = &dax_region->res;
 761         struct device *dev = &dev_dax->dev;
 762         struct dev_dax_range *ranges;
 763         unsigned long pgoff = 0;
 764         struct resource *alloc;
 765         int i, rc;
 766
 767         device_lock_assert(dax_region->dev);
 768
 769         /* handle the seed alloc special case */
 770         if (!size) {
 771                 if (dev_WARN_ONCE(dev, dev_dax->nr_range,
 772                                         "0-size allocation must be first\n"))
 773                         return -EBUSY;
 774                 /* nr_range == 0 is elsewhere special cased as 0-size device */
 775                 return 0;
 776         }
 777
 778         alloc = __request_region(res, start, size, dev_name(dev), 0);
 779         if (!alloc)
 780                 return -ENOMEM;
 781
 782         ranges = krealloc(dev_dax->ranges, sizeof(*ranges)
 783                         * (dev_dax->nr_range + 1), GFP_KERNEL);
 784         if (!ranges) {
 785                 __release_region(res, alloc->start, resource_size(alloc));
 786                 return -ENOMEM;
 787         }
 788
 789         for (i = 0; i < dev_dax->nr_range; i++)
 790                 pgoff += PHYS_PFN(range_len(&ranges[i].range));
 791         dev_dax->ranges = ranges;
 792         ranges[dev_dax->nr_range++] = (struct dev_dax_range) {
 793                 .pgoff = pgoff,
 794                 .range = {
 795                         .start = alloc->start,
 796                         .end = alloc->end,
 797                 },
 798         };
 799
 800         dev_dbg(dev, "alloc range[%d]: %pa:%pa\n", dev_dax->nr_range - 1,
 801                         &alloc->start, &alloc->end);
 802         /*
 803          * A dev_dax instance must be registered before mapping device
 804          * children can be added. Defer to devm_create_dev_dax() to add
 805          * the initial mapping device.
 806          */
 807         if (!device_is_registered(&dev_dax->dev))
 808                 return 0;
 809
 810         rc = devm_register_dax_mapping(dev_dax, dev_dax->nr_range - 1);
 811         if (rc)
 812                 trim_dev_dax_range(dev_dax);
 813
 814         return rc;
 815 }
 816
 817 static int adjust_dev_dax_range(struct dev_dax *dev_dax, struct resource *res, resource_size_t size)
 818 {
 819         int last_range = dev_dax->nr_range - 1;
 820         struct dev_dax_range *dax_range = &dev_dax->ranges[last_range];
 821         struct dax_region *dax_region = dev_dax->region;
 822         bool is_shrink = resource_size(res) > size;
 823         struct range *range = &dax_range->range;
 824         struct device *dev = &dev_dax->dev;
 825         int rc;
 826
 827         device_lock_assert(dax_region->dev);
 828
 829         if (dev_WARN_ONCE(dev, !size, "deletion is handled by dev_dax_shrink\n"))
 830                 return -EINVAL;
 831
 832         rc = adjust_resource(res, range->start, size);
 833         if (rc)
 834                 return rc;
 835
 836         *range = (struct range) {
 837                 .start = range->start,
 838                 .end = range->start + size - 1,
 839         };
 840
 841         dev_dbg(dev, "%s range[%d]: %#llx:%#llx\n", is_shrink ? "shrink" : "extend",
 842                         last_range, (unsigned long long) range->start,
 843                         (unsigned long long) range->end);
 844
 845         return 0;
 846 }
 847
 848 static ssize_t size_show(struct device *dev,
 849                 struct device_attribute *attr, char *buf)
 850 {
 851         struct dev_dax *dev_dax = to_dev_dax(dev);
 852         unsigned long long size;
 853
 854         device_lock(dev);
 855         size = dev_dax_size(dev_dax);
 856         device_unlock(dev);
 857
 858         return sprintf(buf, "%llu\n", size);
 859 }
 860
 861 static bool alloc_is_aligned(struct dev_dax *dev_dax, resource_size_t size)
 862 {
 863         /*
 864          * The minimum mapping granularity for a device instance is a
 865          * single subsection, unless the arch says otherwise.
 866          */
 867         return IS_ALIGNED(size, max_t(unsigned long, dev_dax->align, memremap_compat_align()));
 868 }
 869
 870 static int dev_dax_shrink(struct dev_dax *dev_dax, resource_size_t size)
 871 {
 872         resource_size_t to_shrink = dev_dax_size(dev_dax) - size;
 873         struct dax_region *dax_region = dev_dax->region;
 874         struct device *dev = &dev_dax->dev;
 875         int i;
 876
 877         for (i = dev_dax->nr_range - 1; i >= 0; i--) {
 878                 struct range *range = &dev_dax->ranges[i].range;
 879                 struct dax_mapping *mapping = dev_dax->ranges[i].mapping;
 880                 struct resource *adjust = NULL, *res;
 881                 resource_size_t shrink;
 882
 883                 shrink = min_t(u64, to_shrink, range_len(range));
 884                 if (shrink >= range_len(range)) {
 885                         devm_release_action(dax_region->dev,
 886                                         unregister_dax_mapping, &mapping->dev);
 887                         trim_dev_dax_range(dev_dax);
 888                         to_shrink -= shrink;
 889                         if (!to_shrink)
 890                                 break;
 891                         continue;
 892                 }
 893
 894                 for_each_dax_region_resource(dax_region, res)
 895                         if (strcmp(res->name, dev_name(dev)) == 0
 896                                         && res->start == range->start) {
 897                                 adjust = res;
 898                                 break;
 899                         }
 900
 901                 if (dev_WARN_ONCE(dev, !adjust || i != dev_dax->nr_range - 1,
 902                                         "failed to find matching resource\n"))
 903                         return -ENXIO;
 904                 return adjust_dev_dax_range(dev_dax, adjust, range_len(range)
 905                                 - shrink);
 906         }
 907         return 0;
 908 }
 909
 910 /*
 911  * Only allow adjustments that preserve the relative pgoff of existing
 912  * allocations. I.e. the dev_dax->ranges array is ordered by increasing pgoff.
 913  */
 914 static bool adjust_ok(struct dev_dax *dev_dax, struct resource *res)
 915 {
 916         struct dev_dax_range *last;
 917         int i;
 918
 919         if (dev_dax->nr_range == 0)
 920                 return false;
 921         if (strcmp(res->name, dev_name(&dev_dax->dev)) != 0)
 922                 return false;
 923         last = &dev_dax->ranges[dev_dax->nr_range - 1];
 924         if (last->range.start != res->start || last->range.end != res->end)
 925                 return false;
 926         for (i = 0; i < dev_dax->nr_range - 1; i++) {
 927                 struct dev_dax_range *dax_range = &dev_dax->ranges[i];
 928
 929                 if (dax_range->pgoff > last->pgoff)
 930                         return false;
 931         }
 932
 933         return true;
 934 }
 935
 936 static ssize_t dev_dax_resize(struct dax_region *dax_region,
 937                 struct dev_dax *dev_dax, resource_size_t size)
 938 {
 939         resource_size_t avail = dax_region_avail_size(dax_region), to_alloc;
 940         resource_size_t dev_size = dev_dax_size(dev_dax);
 941         struct resource *region_res = &dax_region->res;
 942         struct device *dev = &dev_dax->dev;
 943         struct resource *res, *first;
 944         resource_size_t alloc = 0;
 945         int rc;
 946
 947         if (dev->driver)
 948                 return -EBUSY;
 949         if (size == dev_size)
 950                 return 0;
 951         if (size > dev_size && size - dev_size > avail)
 952                 return -ENOSPC;
 953         if (size < dev_size)
 954                 return dev_dax_shrink(dev_dax, size);
 955
 956         to_alloc = size - dev_size;
 957         if (dev_WARN_ONCE(dev, !alloc_is_aligned(dev_dax, to_alloc),
 958                         "resize of %pa misaligned\n", &to_alloc))
 959                 return -ENXIO;
 960
 961         /*
 962          * Expand the device into the unused portion of the region. This
 963          * may involve adjusting the end of an existing resource, or
 964          * allocating a new resource.
 965          */
 966 retry:
 967         first = region_res->child;
 968         if (!first)
 969                 return alloc_dev_dax_range(dev_dax, dax_region->res.start, to_alloc);
 970
 971         rc = -ENOSPC;
 972         for (res = first; res; res = res->sibling) {
 973                 struct resource *next = res->sibling;
 974
 975                 /* space at the beginning of the region */
 976                 if (res == first && res->start > dax_region->res.start) {
 977                         alloc = min(res->start - dax_region->res.start, to_alloc);
 978                         rc = alloc_dev_dax_range(dev_dax, dax_region->res.start, alloc);
 979                         break;
 980                 }
 981
 982                 alloc = 0;
 983                 /* space between allocations */
 984                 if (next && next->start > res->end + 1)
 985                         alloc = min(next->start - (res->end + 1), to_alloc);
 986
 987                 /* space at the end of the region */
 988                 if (!alloc && !next && res->end < region_res->end)
 989                         alloc = min(region_res->end - res->end, to_alloc);
 990
 991                 if (!alloc)
 992                         continue;
 993
 994                 if (adjust_ok(dev_dax, res)) {
 995                         rc = adjust_dev_dax_range(dev_dax, res, resource_size(res) + alloc);
 996                         break;
 997                 }
 998                 rc = alloc_dev_dax_range(dev_dax, res->end + 1, alloc);
 999                 break;
1000         }
1001         if (rc)
1002                 return rc;
1003         to_alloc -= alloc;
1004         if (to_alloc)
1005                 goto retry;
1006         return 0;
1007 }
1008
1009 static ssize_t size_store(struct device *dev, struct device_attribute *attr,
1010                 const char *buf, size_t len)
1011 {
1012         ssize_t rc;
1013         unsigned long long val;
1014         struct dev_dax *dev_dax = to_dev_dax(dev);
1015         struct dax_region *dax_region = dev_dax->region;
1016
1017         rc = kstrtoull(buf, 0, &val);
1018         if (rc)
1019                 return rc;
1020
1021         if (!alloc_is_aligned(dev_dax, val)) {
1022                 dev_dbg(dev, "%s: size: %lld misaligned\n", __func__, val);
1023                 return -EINVAL;
1024         }
1025
1026         device_lock(dax_region->dev);
1027         if (!dax_region->dev->driver) {
1028                 device_unlock(dax_region->dev);
1029                 return -ENXIO;
1030         }
1031         device_lock(dev);
1032         rc = dev_dax_resize(dax_region, dev_dax, val);
1033         device_unlock(dev);
1034         device_unlock(dax_region->dev);
1035
1036         return rc == 0 ? len : rc;
1037 }
1038 static DEVICE_ATTR_RW(size);
1039
1040 static ssize_t range_parse(const char *opt, size_t len, struct range *range)
1041 {
1042         unsigned long long addr = 0;
1043         char *start, *end, *str;
1044         ssize_t rc = -EINVAL;
1045
1046         str = kstrdup(opt, GFP_KERNEL);
1047         if (!str)
1048                 return rc;
1049
1050         end = str;
1051         start = strsep(&end, "-");
1052         if (!start || !end)
1053                 goto err;
1054
1055         rc = kstrtoull(start, 16, &addr);
1056         if (rc)
1057                 goto err;
1058         range->start = addr;
1059
1060         rc = kstrtoull(end, 16, &addr);
1061         if (rc)
1062                 goto err;
1063         range->end = addr;
1064
1065 err:
1066         kfree(str);
1067         return rc;
1068 }
1069
1070 static ssize_t mapping_store(struct device *dev, struct device_attribute *attr,
1071                 const char *buf, size_t len)
1072 {
1073         struct dev_dax *dev_dax = to_dev_dax(dev);
1074         struct dax_region *dax_region = dev_dax->region;
1075         size_t to_alloc;
1076         struct range r;
1077         ssize_t rc;
1078
1079         rc = range_parse(buf, len, &r);
1080         if (rc)
1081                 return rc;
1082
1083         rc = -ENXIO;
1084         device_lock(dax_region->dev);
1085         if (!dax_region->dev->driver) {
1086                 device_unlock(dax_region->dev);
1087                 return rc;
1088         }
1089         device_lock(dev);
1090
1091         to_alloc = range_len(&r);
1092         if (alloc_is_aligned(dev_dax, to_alloc))
1093                 rc = alloc_dev_dax_range(dev_dax, r.start, to_alloc);
1094         device_unlock(dev);
1095         device_unlock(dax_region->dev);
1096
1097         return rc == 0 ? len : rc;
1098 }
1099 static DEVICE_ATTR_WO(mapping);
1100
1101 static ssize_t align_show(struct device *dev,
1102                 struct device_attribute *attr, char *buf)
1103 {
1104         struct dev_dax *dev_dax = to_dev_dax(dev);
1105
1106         return sprintf(buf, "%d\n", dev_dax->align);
1107 }
1108
1109 static ssize_t dev_dax_validate_align(struct dev_dax *dev_dax)
1110 {
1111         struct device *dev = &dev_dax->dev;
1112         int i;
1113
1114         for (i = 0; i < dev_dax->nr_range; i++) {
1115                 size_t len = range_len(&dev_dax->ranges[i].range);
1116
1117                 if (!alloc_is_aligned(dev_dax, len)) {
1118                         dev_dbg(dev, "%s: align %u invalid for range %d\n",
1119                                 __func__, dev_dax->align, i);
1120                         return -EINVAL;
1121                 }
1122         }
1123
1124         return 0;
1125 }
1126
1127 static ssize_t align_store(struct device *dev, struct device_attribute *attr,
1128                 const char *buf, size_t len)
1129 {
1130         struct dev_dax *dev_dax = to_dev_dax(dev);
1131         struct dax_region *dax_region = dev_dax->region;
1132         unsigned long val, align_save;
1133         ssize_t rc;
1134
1135         rc = kstrtoul(buf, 0, &val);
1136         if (rc)
1137                 return -ENXIO;
1138
1139         if (!dax_align_valid(val))
1140                 return -EINVAL;
1141
1142         device_lock(dax_region->dev);
1143         if (!dax_region->dev->driver) {
1144                 device_unlock(dax_region->dev);
1145                 return -ENXIO;
1146         }
1147
1148         device_lock(dev);
1149         if (dev->driver) {
1150                 rc = -EBUSY;
1151                 goto out_unlock;
1152         }
1153
1154         align_save = dev_dax->align;
1155         dev_dax->align = val;
1156         rc = dev_dax_validate_align(dev_dax);
1157         if (rc)
1158                 dev_dax->align = align_save;
1159 out_unlock:
1160         device_unlock(dev);
1161         device_unlock(dax_region->dev);
1162         return rc == 0 ? len : rc;
1163 }
1164 static DEVICE_ATTR_RW(align);
1165
1166 static int dev_dax_target_node(struct dev_dax *dev_dax)
1167 {
1168         struct dax_region *dax_region = dev_dax->region;
1169
1170         return dax_region->target_node;
1171 }
1172
1173 static ssize_t target_node_show(struct device *dev,
1174                 struct device_attribute *attr, char *buf)
1175 {
1176         struct dev_dax *dev_dax = to_dev_dax(dev);
1177
1178         return sprintf(buf, "%d\n", dev_dax_target_node(dev_dax));
1179 }
1180 static DEVICE_ATTR_RO(target_node);
1181
1182 static ssize_t resource_show(struct device *dev,
1183                 struct device_attribute *attr, char *buf)
1184 {
1185         struct dev_dax *dev_dax = to_dev_dax(dev);
1186         struct dax_region *dax_region = dev_dax->region;
1187         unsigned long long start;
1188
1189         if (dev_dax->nr_range < 1)
1190                 start = dax_region->res.start;
1191         else
1192                 start = dev_dax->ranges[0].range.start;
1193
1194         return sprintf(buf, "%#llx\n", start);
1195 }
1196 static DEVICE_ATTR(resource, 0400, resource_show, NULL);
1197
1198 static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
1199                 char *buf)
1200 {
1201         /*
1202          * We only ever expect to handle device-dax instances, i.e. the
1203          * @type argument to MODULE_ALIAS_DAX_DEVICE() is always zero
1204          */
1205         return sprintf(buf, DAX_DEVICE_MODALIAS_FMT "\n", 0);
1206 }
1207 static DEVICE_ATTR_RO(modalias);
1208
1209 static ssize_t numa_node_show(struct device *dev,
1210                 struct device_attribute *attr, char *buf)
1211 {
1212         return sprintf(buf, "%d\n", dev_to_node(dev));
1213 }
1214 static DEVICE_ATTR_RO(numa_node);
1215
1216 static umode_t dev_dax_visible(struct kobject *kobj, struct attribute *a, int n)
1217 {
1218         struct device *dev = container_of(kobj, struct device, kobj);
1219         struct dev_dax *dev_dax = to_dev_dax(dev);
1220         struct dax_region *dax_region = dev_dax->region;
1221
1222         if (a == &dev_attr_target_node.attr && dev_dax_target_node(dev_dax) < 0)
1223                 return 0;
1224         if (a == &dev_attr_numa_node.attr && !IS_ENABLED(CONFIG_NUMA))
1225                 return 0;
1226         if (a == &dev_attr_mapping.attr && is_static(dax_region))
1227                 return 0;
1228         if ((a == &dev_attr_align.attr ||
1229              a == &dev_attr_size.attr) && is_static(dax_region))
1230                 return 0444;
1231         return a->mode;
1232 }
1233
1234 static struct attribute *dev_dax_attributes[] = {
1235         &dev_attr_modalias.attr,
1236         &dev_attr_size.attr,
1237         &dev_attr_mapping.attr,
1238         &dev_attr_target_node.attr,
1239         &dev_attr_align.attr,
1240         &dev_attr_resource.attr,
1241         &dev_attr_numa_node.attr,
1242         NULL,
1243 };
1244
1245 static const struct attribute_group dev_dax_attribute_group = {
1246         .attrs = dev_dax_attributes,
1247         .is_visible = dev_dax_visible,
1248 };
1249
1250 static const struct attribute_group *dax_attribute_groups[] = {
1251         &dev_dax_attribute_group,
1252         NULL,
1253 };
1254
1255 static void dev_dax_release(struct device *dev)
1256 {
1257         struct dev_dax *dev_dax = to_dev_dax(dev);
1258         struct dax_region *dax_region = dev_dax->region;
1259         struct dax_device *dax_dev = dev_dax->dax_dev;
1260
1261         put_dax(dax_dev);
1262         free_dev_dax_id(dev_dax);
1263         dax_region_put(dax_region);
1264         kfree(dev_dax->pgmap);
1265         kfree(dev_dax);
1266 }
1267
1268 static const struct device_type dev_dax_type = {
1269         .release = dev_dax_release,
1270         .groups = dax_attribute_groups,
1271 };
1272
1273 struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
1274 {
1275         struct dax_region *dax_region = data->dax_region;
1276         struct device *parent = dax_region->dev;
1277         struct dax_device *dax_dev;
1278         struct dev_dax *dev_dax;
1279         struct inode *inode;
1280         struct device *dev;
1281         int rc;
1282
1283         dev_dax = kzalloc(sizeof(*dev_dax), GFP_KERNEL);
1284         if (!dev_dax)
1285                 return ERR_PTR(-ENOMEM);
1286
1287         if (is_static(dax_region)) {
1288                 if (dev_WARN_ONCE(parent, data->id < 0,
1289                                 "dynamic id specified to static region\n")) {
1290                         rc = -EINVAL;
1291                         goto err_id;
1292                 }
1293
1294                 dev_dax->id = data->id;
1295         } else {
1296                 if (dev_WARN_ONCE(parent, data->id >= 0,
1297                                 "static id specified to dynamic region\n")) {
1298                         rc = -EINVAL;
1299                         goto err_id;
1300                 }
1301
1302                 rc = ida_alloc(&dax_region->ida, GFP_KERNEL);
1303                 if (rc < 0)
1304                         goto err_id;
1305                 dev_dax->id = rc;
1306         }
1307
1308         dev_dax->region = dax_region;
1309         dev = &dev_dax->dev;
1310         device_initialize(dev);
1311         dev_set_name(dev, "dax%d.%d", dax_region->id, dev_dax->id);
1312
1313         rc = alloc_dev_dax_range(dev_dax, dax_region->res.start, data->size);
1314         if (rc)
1315                 goto err_range;
1316
1317         if (data->pgmap) {
1318                 dev_WARN_ONCE(parent, !is_static(dax_region),
1319                         "custom dev_pagemap requires a static dax_region\n");
1320
1321                 dev_dax->pgmap = kmemdup(data->pgmap,
1322                                 sizeof(struct dev_pagemap), GFP_KERNEL);
1323                 if (!dev_dax->pgmap) {
1324                         rc = -ENOMEM;
1325                         goto err_pgmap;
1326                 }
1327         }
1328
1329         /*
1330          * No 'host' or dax_operations since there is no access to this
1331          * device outside of mmap of the resulting character device.
1332          */
1333         dax_dev = alloc_dax(dev_dax, NULL, NULL, DAXDEV_F_SYNC);
1334         if (IS_ERR(dax_dev)) {
1335                 rc = PTR_ERR(dax_dev);
1336                 goto err_alloc_dax;
1337         }
1338
1339         /* a device_dax instance is dead while the driver is not attached */
1340         kill_dax(dax_dev);
1341
1342         dev_dax->dax_dev = dax_dev;
1343         dev_dax->target_node = dax_region->target_node;
1344         dev_dax->align = dax_region->align;
1345         ida_init(&dev_dax->ida);
1346         kref_get(&dax_region->kref);
1347
1348         inode = dax_inode(dax_dev);
1349         dev->devt = inode->i_rdev;
1350         if (data->subsys == DEV_DAX_BUS)
1351                 dev->bus = &dax_bus_type;
1352         else
1353                 dev->class = dax_class;
1354         dev->parent = parent;
1355         dev->type = &dev_dax_type;
1356
1357         rc = device_add(dev);
1358         if (rc) {
1359                 kill_dev_dax(dev_dax);
1360                 put_device(dev);
1361                 return ERR_PTR(rc);
1362         }
1363
1364         rc = devm_add_action_or_reset(dax_region->dev, unregister_dev_dax, dev);
1365         if (rc)
1366                 return ERR_PTR(rc);
1367
1368         /* register mapping device for the initial allocation range */
1369         if (dev_dax->nr_range && range_len(&dev_dax->ranges[0].range)) {
1370                 rc = devm_register_dax_mapping(dev_dax, 0);
1371                 if (rc)
1372                         return ERR_PTR(rc);
1373         }
1374
1375         return dev_dax;
1376
1377 err_alloc_dax:
1378         kfree(dev_dax->pgmap);
1379 err_pgmap:
1380         free_dev_dax_ranges(dev_dax);
1381 err_range:
1382         free_dev_dax_id(dev_dax);
1383 err_id:
1384         kfree(dev_dax);
1385
1386         return ERR_PTR(rc);
1387 }
1388 EXPORT_SYMBOL_GPL(devm_create_dev_dax);
1389
1390 static int match_always_count;
1391
1392 int __dax_driver_register(struct dax_device_driver *dax_drv,
1393                 struct module *module, const char *mod_name)
1394 {
1395         struct device_driver *drv = &dax_drv->drv;
1396         int rc = 0;
1397
1398         /*
1399          * dax_bus_probe() calls dax_drv->probe() unconditionally.
1400          * So better be safe than sorry and ensure it is provided.
1401          */
1402         if (!dax_drv->probe)
1403                 return -EINVAL;
1404
1405         INIT_LIST_HEAD(&dax_drv->ids);
1406         drv->owner = module;
1407         drv->name = mod_name;
1408         drv->mod_name = mod_name;
1409         drv->bus = &dax_bus_type;
1410
1411         /* there can only be one default driver */
1412         mutex_lock(&dax_bus_lock);
1413         match_always_count += dax_drv->match_always;
1414         if (match_always_count > 1) {
1415                 match_always_count--;
1416                 WARN_ON(1);
1417                 rc = -EINVAL;
1418         }
1419         mutex_unlock(&dax_bus_lock);
1420         if (rc)
1421                 return rc;
1422
1423         rc = driver_register(drv);
1424         if (rc && dax_drv->match_always) {
1425                 mutex_lock(&dax_bus_lock);
1426                 match_always_count -= dax_drv->match_always;
1427                 mutex_unlock(&dax_bus_lock);
1428         }
1429
1430         return rc;
1431 }
1432 EXPORT_SYMBOL_GPL(__dax_driver_register);
1433
1434 void dax_driver_unregister(struct dax_device_driver *dax_drv)
1435 {
1436         struct device_driver *drv = &dax_drv->drv;
1437         struct dax_id *dax_id, *_id;
1438
1439         mutex_lock(&dax_bus_lock);
1440         match_always_count -= dax_drv->match_always;
1441         list_for_each_entry_safe(dax_id, _id, &dax_drv->ids, list) {
1442                 list_del(&dax_id->list);
1443                 kfree(dax_id);
1444         }
1445         mutex_unlock(&dax_bus_lock);
1446         driver_unregister(drv);
1447 }
1448 EXPORT_SYMBOL_GPL(dax_driver_unregister);
1449
1450 int __init dax_bus_init(void)
1451 {
1452         int rc;
1453
1454         if (IS_ENABLED(CONFIG_DEV_DAX_PMEM_COMPAT)) {
1455                 dax_class = class_create(THIS_MODULE, "dax");
1456                 if (IS_ERR(dax_class))
1457                         return PTR_ERR(dax_class);
1458         }
1459
1460         rc = bus_register(&dax_bus_type);
1461         if (rc)
1462                 class_destroy(dax_class);
1463         return rc;
1464 }
1465
1466 void __exit dax_bus_exit(void)
1467 {
1468         bus_unregister(&dax_bus_type);
1469         class_destroy(dax_class);
1470 }