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 "dax-private.h"
  10 #include "bus.h"
  11
  12 static struct class *dax_class;
  13
  14 static DEFINE_MUTEX(dax_bus_lock);
  15
  16 #define DAX_NAME_LEN 30
  17 struct dax_id {
  18         struct list_head list;
  19         char dev_name[DAX_NAME_LEN];
  20 };
  21
  22 static int dax_bus_uevent(struct device *dev, struct kobj_uevent_env *env)
  23 {
  24         /*
  25          * We only ever expect to handle device-dax instances, i.e. the
  26          * @type argument to MODULE_ALIAS_DAX_DEVICE() is always zero
  27          */
  28         return add_uevent_var(env, "MODALIAS=" DAX_DEVICE_MODALIAS_FMT, 0);
  29 }
  30
  31 static struct dax_device_driver *to_dax_drv(struct device_driver *drv)
  32 {
  33         return container_of(drv, struct dax_device_driver, drv);
  34 }
  35
  36 static struct dax_id *__dax_match_id(struct dax_device_driver *dax_drv,
  37                 const char *dev_name)
  38 {
  39         struct dax_id *dax_id;
  40
  41         lockdep_assert_held(&dax_bus_lock);
  42
  43         list_for_each_entry(dax_id, &dax_drv->ids, list)
  44                 if (sysfs_streq(dax_id->dev_name, dev_name))
  45                         return dax_id;
  46         return NULL;
  47 }
  48
  49 static int dax_match_id(struct dax_device_driver *dax_drv, struct device *dev)
  50 {
  51         int match;
  52
  53         mutex_lock(&dax_bus_lock);
  54         match = !!__dax_match_id(dax_drv, dev_name(dev));
  55         mutex_unlock(&dax_bus_lock);
  56
  57         return match;
  58 }
  59
  60 enum id_action {
  61         ID_REMOVE,
  62         ID_ADD,
  63 };
  64
  65 static ssize_t do_id_store(struct device_driver *drv, const char *buf,
  66                 size_t count, enum id_action action)
  67 {
  68         struct dax_device_driver *dax_drv = to_dax_drv(drv);
  69         unsigned int region_id, id;
  70         char devname[DAX_NAME_LEN];
  71         struct dax_id *dax_id;
  72         ssize_t rc = count;
  73         int fields;
  74
  75         fields = sscanf(buf, "dax%d.%d", &region_id, &id);
  76         if (fields != 2)
  77                 return -EINVAL;
  78         sprintf(devname, "dax%d.%d", region_id, id);
  79         if (!sysfs_streq(buf, devname))
  80                 return -EINVAL;
  81
  82         mutex_lock(&dax_bus_lock);
  83         dax_id = __dax_match_id(dax_drv, buf);
  84         if (!dax_id) {
  85                 if (action == ID_ADD) {
  86                         dax_id = kzalloc(sizeof(*dax_id), GFP_KERNEL);
  87                         if (dax_id) {
  88                                 strncpy(dax_id->dev_name, buf, DAX_NAME_LEN);
  89                                 list_add(&dax_id->list, &dax_drv->ids);
  90                         } else
  91                                 rc = -ENOMEM;
  92                 } else
  93                         /* nothing to remove */;
  94         } else if (action == ID_REMOVE) {
  95                 list_del(&dax_id->list);
  96                 kfree(dax_id);
  97         } else
  98                 /* dax_id already added */;
  99         mutex_unlock(&dax_bus_lock);
 100
 101         if (rc < 0)
 102                 return rc;
 103         if (action == ID_ADD)
 104                 rc = driver_attach(drv);
 105         if (rc)
 106                 return rc;
 107         return count;
 108 }
 109
 110 static ssize_t new_id_store(struct device_driver *drv, const char *buf,
 111                 size_t count)
 112 {
 113         return do_id_store(drv, buf, count, ID_ADD);
 114 }
 115 static DRIVER_ATTR_WO(new_id);
 116
 117 static ssize_t remove_id_store(struct device_driver *drv, const char *buf,
 118                 size_t count)
 119 {
 120         return do_id_store(drv, buf, count, ID_REMOVE);
 121 }
 122 static DRIVER_ATTR_WO(remove_id);
 123
 124 static struct attribute *dax_drv_attrs[] = {
 125         &driver_attr_new_id.attr,
 126         &driver_attr_remove_id.attr,
 127         NULL,
 128 };
 129 ATTRIBUTE_GROUPS(dax_drv);
 130
 131 static int dax_bus_match(struct device *dev, struct device_driver *drv);
 132
 133 static struct bus_type dax_bus_type = {
 134         .name = "dax",
 135         .uevent = dax_bus_uevent,
 136         .match = dax_bus_match,
 137         .drv_groups = dax_drv_groups,
 138 };
 139
 140 static int dax_bus_match(struct device *dev, struct device_driver *drv)
 141 {
 142         struct dax_device_driver *dax_drv = to_dax_drv(drv);
 143
 144         /*
 145          * All but the 'device-dax' driver, which has 'match_always'
 146          * set, requires an exact id match.
 147          */
 148         if (dax_drv->match_always)
 149                 return 1;
 150
 151         return dax_match_id(dax_drv, dev);
 152 }
 153
 154 /*
 155  * Rely on the fact that drvdata is set before the attributes are
 156  * registered, and that the attributes are unregistered before drvdata
 157  * is cleared to assume that drvdata is always valid.
 158  */
 159 static ssize_t id_show(struct device *dev,
 160                 struct device_attribute *attr, char *buf)
 161 {
 162         struct dax_region *dax_region = dev_get_drvdata(dev);
 163
 164         return sprintf(buf, "%d\n", dax_region->id);
 165 }
 166 static DEVICE_ATTR_RO(id);
 167
 168 static ssize_t region_size_show(struct device *dev,
 169                 struct device_attribute *attr, char *buf)
 170 {
 171         struct dax_region *dax_region = dev_get_drvdata(dev);
 172
 173         return sprintf(buf, "%llu\n", (unsigned long long)
 174                         resource_size(&dax_region->res));
 175 }
 176 static struct device_attribute dev_attr_region_size = __ATTR(size, 0444,
 177                 region_size_show, NULL);
 178
 179 static ssize_t align_show(struct device *dev,
 180                 struct device_attribute *attr, char *buf)
 181 {
 182         struct dax_region *dax_region = dev_get_drvdata(dev);
 183
 184         return sprintf(buf, "%u\n", dax_region->align);
 185 }
 186 static DEVICE_ATTR_RO(align);
 187
 188 static struct attribute *dax_region_attributes[] = {
 189         &dev_attr_region_size.attr,
 190         &dev_attr_align.attr,
 191         &dev_attr_id.attr,
 192         NULL,
 193 };
 194
 195 static const struct attribute_group dax_region_attribute_group = {
 196         .name = "dax_region",
 197         .attrs = dax_region_attributes,
 198 };
 199
 200 static const struct attribute_group *dax_region_attribute_groups[] = {
 201         &dax_region_attribute_group,
 202         NULL,
 203 };
 204
 205 static void dax_region_free(struct kref *kref)
 206 {
 207         struct dax_region *dax_region;
 208
 209         dax_region = container_of(kref, struct dax_region, kref);
 210         kfree(dax_region);
 211 }
 212
 213 void dax_region_put(struct dax_region *dax_region)
 214 {
 215         kref_put(&dax_region->kref, dax_region_free);
 216 }
 217 EXPORT_SYMBOL_GPL(dax_region_put);
 218
 219 static void dax_region_unregister(void *region)
 220 {
 221         struct dax_region *dax_region = region;
 222
 223         sysfs_remove_groups(&dax_region->dev->kobj,
 224                         dax_region_attribute_groups);
 225         dax_region_put(dax_region);
 226 }
 227
 228 struct dax_region *alloc_dax_region(struct device *parent, int region_id,
 229                 struct resource *res, int target_node, unsigned int align,
 230                 unsigned long pfn_flags)
 231 {
 232         struct dax_region *dax_region;
 233
 234         /*
 235          * The DAX core assumes that it can store its private data in
 236          * parent->driver_data. This WARN is a reminder / safeguard for
 237          * developers of device-dax drivers.
 238          */
 239         if (dev_get_drvdata(parent)) {
 240                 dev_WARN(parent, "dax core failed to setup private data\n");
 241                 return NULL;
 242         }
 243
 244         if (!IS_ALIGNED(res->start, align)
 245                         || !IS_ALIGNED(resource_size(res), align))
 246                 return NULL;
 247
 248         dax_region = kzalloc(sizeof(*dax_region), GFP_KERNEL);
 249         if (!dax_region)
 250                 return NULL;
 251
 252         dev_set_drvdata(parent, dax_region);
 253         memcpy(&dax_region->res, res, sizeof(*res));
 254         dax_region->pfn_flags = pfn_flags;
 255         kref_init(&dax_region->kref);
 256         dax_region->id = region_id;
 257         dax_region->align = align;
 258         dax_region->dev = parent;
 259         dax_region->target_node = target_node;
 260         if (sysfs_create_groups(&parent->kobj, dax_region_attribute_groups)) {
 261                 kfree(dax_region);
 262                 return NULL;
 263         }
 264
 265         kref_get(&dax_region->kref);
 266         if (devm_add_action_or_reset(parent, dax_region_unregister, dax_region))
 267                 return NULL;
 268         return dax_region;
 269 }
 270 EXPORT_SYMBOL_GPL(alloc_dax_region);
 271
 272 static ssize_t size_show(struct device *dev,
 273                 struct device_attribute *attr, char *buf)
 274 {
 275         struct dev_dax *dev_dax = to_dev_dax(dev);
 276         unsigned long long size = resource_size(&dev_dax->region->res);
 277
 278         return sprintf(buf, "%llu\n", size);
 279 }
 280 static DEVICE_ATTR_RO(size);
 281
 282 static int dev_dax_target_node(struct dev_dax *dev_dax)
 283 {
 284         struct dax_region *dax_region = dev_dax->region;
 285
 286         return dax_region->target_node;
 287 }
 288
 289 static ssize_t target_node_show(struct device *dev,
 290                 struct device_attribute *attr, char *buf)
 291 {
 292         struct dev_dax *dev_dax = to_dev_dax(dev);
 293
 294         return sprintf(buf, "%d\n", dev_dax_target_node(dev_dax));
 295 }
 296 static DEVICE_ATTR_RO(target_node);
 297
 298 static unsigned long long dev_dax_resource(struct dev_dax *dev_dax)
 299 {
 300         struct dax_region *dax_region = dev_dax->region;
 301
 302         return dax_region->res.start;
 303 }
 304
 305 static ssize_t resource_show(struct device *dev,
 306                 struct device_attribute *attr, char *buf)
 307 {
 308         struct dev_dax *dev_dax = to_dev_dax(dev);
 309
 310         return sprintf(buf, "%#llx\n", dev_dax_resource(dev_dax));
 311 }
 312 static DEVICE_ATTR_RO(resource);
 313
 314 static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
 315                 char *buf)
 316 {
 317         /*
 318          * We only ever expect to handle device-dax instances, i.e. the
 319          * @type argument to MODULE_ALIAS_DAX_DEVICE() is always zero
 320          */
 321         return sprintf(buf, DAX_DEVICE_MODALIAS_FMT "\n", 0);
 322 }
 323 static DEVICE_ATTR_RO(modalias);
 324
 325 static umode_t dev_dax_visible(struct kobject *kobj, struct attribute *a, int n)
 326 {
 327         struct device *dev = container_of(kobj, struct device, kobj);
 328         struct dev_dax *dev_dax = to_dev_dax(dev);
 329
 330         if (a == &dev_attr_target_node.attr && dev_dax_target_node(dev_dax) < 0)
 331                 return 0;
 332         if (a == &dev_attr_resource.attr)
 333                 return 0400;
 334         return a->mode;
 335 }
 336
 337 static struct attribute *dev_dax_attributes[] = {
 338         &dev_attr_modalias.attr,
 339         &dev_attr_size.attr,
 340         &dev_attr_target_node.attr,
 341         &dev_attr_resource.attr,
 342         NULL,
 343 };
 344
 345 static const struct attribute_group dev_dax_attribute_group = {
 346         .attrs = dev_dax_attributes,
 347         .is_visible = dev_dax_visible,
 348 };
 349
 350 static const struct attribute_group *dax_attribute_groups[] = {
 351         &dev_dax_attribute_group,
 352         NULL,
 353 };
 354
 355 void kill_dev_dax(struct dev_dax *dev_dax)
 356 {
 357         struct dax_device *dax_dev = dev_dax->dax_dev;
 358         struct inode *inode = dax_inode(dax_dev);
 359
 360         kill_dax(dax_dev);
 361         unmap_mapping_range(inode->i_mapping, 0, 0, 1);
 362 }
 363 EXPORT_SYMBOL_GPL(kill_dev_dax);
 364
 365 static void dev_dax_release(struct device *dev)
 366 {
 367         struct dev_dax *dev_dax = to_dev_dax(dev);
 368         struct dax_region *dax_region = dev_dax->region;
 369         struct dax_device *dax_dev = dev_dax->dax_dev;
 370
 371         dax_region_put(dax_region);
 372         put_dax(dax_dev);
 373         kfree(dev_dax);
 374 }
 375
 376 static void unregister_dev_dax(void *dev)
 377 {
 378         struct dev_dax *dev_dax = to_dev_dax(dev);
 379
 380         dev_dbg(dev, "%s\n", __func__);
 381
 382         kill_dev_dax(dev_dax);
 383         device_del(dev);
 384         put_device(dev);
 385 }
 386
 387 struct dev_dax *__devm_create_dev_dax(struct dax_region *dax_region, int id,
 388                 struct dev_pagemap *pgmap, enum dev_dax_subsys subsys)
 389 {
 390         struct device *parent = dax_region->dev;
 391         struct dax_device *dax_dev;
 392         struct dev_dax *dev_dax;
 393         struct inode *inode;
 394         struct device *dev;
 395         int rc = -ENOMEM;
 396
 397         if (id < 0)
 398                 return ERR_PTR(-EINVAL);
 399
 400         dev_dax = kzalloc(sizeof(*dev_dax), GFP_KERNEL);
 401         if (!dev_dax)
 402                 return ERR_PTR(-ENOMEM);
 403
 404         memcpy(&dev_dax->pgmap, pgmap, sizeof(*pgmap));
 405
 406         /*
 407          * No 'host' or dax_operations since there is no access to this
 408          * device outside of mmap of the resulting character device.
 409          */
 410         dax_dev = alloc_dax(dev_dax, NULL, NULL, DAXDEV_F_SYNC);
 411         if (!dax_dev)
 412                 goto err;
 413
 414         /* a device_dax instance is dead while the driver is not attached */
 415         kill_dax(dax_dev);
 416
 417         /* from here on we're committed to teardown via dax_dev_release() */
 418         dev = &dev_dax->dev;
 419         device_initialize(dev);
 420
 421         dev_dax->dax_dev = dax_dev;
 422         dev_dax->region = dax_region;
 423         dev_dax->target_node = dax_region->target_node;
 424         kref_get(&dax_region->kref);
 425
 426         inode = dax_inode(dax_dev);
 427         dev->devt = inode->i_rdev;
 428         if (subsys == DEV_DAX_BUS)
 429                 dev->bus = &dax_bus_type;
 430         else
 431                 dev->class = dax_class;
 432         dev->parent = parent;
 433         dev->groups = dax_attribute_groups;
 434         dev->release = dev_dax_release;
 435         dev_set_name(dev, "dax%d.%d", dax_region->id, id);
 436
 437         rc = device_add(dev);
 438         if (rc) {
 439                 kill_dev_dax(dev_dax);
 440                 put_device(dev);
 441                 return ERR_PTR(rc);
 442         }
 443
 444         rc = devm_add_action_or_reset(dax_region->dev, unregister_dev_dax, dev);
 445         if (rc)
 446                 return ERR_PTR(rc);
 447
 448         return dev_dax;
 449
 450  err:
 451         kfree(dev_dax);
 452
 453         return ERR_PTR(rc);
 454 }
 455 EXPORT_SYMBOL_GPL(__devm_create_dev_dax);
 456
 457 static int match_always_count;
 458
 459 int __dax_driver_register(struct dax_device_driver *dax_drv,
 460                 struct module *module, const char *mod_name)
 461 {
 462         struct device_driver *drv = &dax_drv->drv;
 463         int rc = 0;
 464
 465         INIT_LIST_HEAD(&dax_drv->ids);
 466         drv->owner = module;
 467         drv->name = mod_name;
 468         drv->mod_name = mod_name;
 469         drv->bus = &dax_bus_type;
 470
 471         /* there can only be one default driver */
 472         mutex_lock(&dax_bus_lock);
 473         match_always_count += dax_drv->match_always;
 474         if (match_always_count > 1) {
 475                 match_always_count--;
 476                 WARN_ON(1);
 477                 rc = -EINVAL;
 478         }
 479         mutex_unlock(&dax_bus_lock);
 480         if (rc)
 481                 return rc;
 482         return driver_register(drv);
 483 }
 484 EXPORT_SYMBOL_GPL(__dax_driver_register);
 485
 486 void dax_driver_unregister(struct dax_device_driver *dax_drv)
 487 {
 488         struct device_driver *drv = &dax_drv->drv;
 489         struct dax_id *dax_id, *_id;
 490
 491         mutex_lock(&dax_bus_lock);
 492         match_always_count -= dax_drv->match_always;
 493         list_for_each_entry_safe(dax_id, _id, &dax_drv->ids, list) {
 494                 list_del(&dax_id->list);
 495                 kfree(dax_id);
 496         }
 497         mutex_unlock(&dax_bus_lock);
 498         driver_unregister(drv);
 499 }
 500 EXPORT_SYMBOL_GPL(dax_driver_unregister);
 501
 502 int __init dax_bus_init(void)
 503 {
 504         int rc;
 505
 506         if (IS_ENABLED(CONFIG_DEV_DAX_PMEM_COMPAT)) {
 507                 dax_class = class_create(THIS_MODULE, "dax");
 508                 if (IS_ERR(dax_class))
 509                         return PTR_ERR(dax_class);
 510         }
 511
 512         rc = bus_register(&dax_bus_type);
 513         if (rc)
 514                 class_destroy(dax_class);
 515         return rc;
 516 }
 517
 518 void __exit dax_bus_exit(void)
 519 {
 520         bus_unregister(&dax_bus_type);
 521         class_destroy(dax_class);
 522 }