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 ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
 299                 char *buf)
 300 {
 301         /*
 302          * We only ever expect to handle device-dax instances, i.e. the
 303          * @type argument to MODULE_ALIAS_DAX_DEVICE() is always zero
 304          */
 305         return sprintf(buf, DAX_DEVICE_MODALIAS_FMT "\n", 0);
 306 }
 307 static DEVICE_ATTR_RO(modalias);
 308
 309 static umode_t dev_dax_visible(struct kobject *kobj, struct attribute *a, int n)
 310 {
 311         struct device *dev = container_of(kobj, struct device, kobj);
 312         struct dev_dax *dev_dax = to_dev_dax(dev);
 313
 314         if (a == &dev_attr_target_node.attr && dev_dax_target_node(dev_dax) < 0)
 315                 return 0;
 316         return a->mode;
 317 }
 318
 319 static struct attribute *dev_dax_attributes[] = {
 320         &dev_attr_modalias.attr,
 321         &dev_attr_size.attr,
 322         &dev_attr_target_node.attr,
 323         NULL,
 324 };
 325
 326 static const struct attribute_group dev_dax_attribute_group = {
 327         .attrs = dev_dax_attributes,
 328         .is_visible = dev_dax_visible,
 329 };
 330
 331 static const struct attribute_group *dax_attribute_groups[] = {
 332         &dev_dax_attribute_group,
 333         NULL,
 334 };
 335
 336 void kill_dev_dax(struct dev_dax *dev_dax)
 337 {
 338         struct dax_device *dax_dev = dev_dax->dax_dev;
 339         struct inode *inode = dax_inode(dax_dev);
 340
 341         kill_dax(dax_dev);
 342         unmap_mapping_range(inode->i_mapping, 0, 0, 1);
 343 }
 344 EXPORT_SYMBOL_GPL(kill_dev_dax);
 345
 346 static void dev_dax_release(struct device *dev)
 347 {
 348         struct dev_dax *dev_dax = to_dev_dax(dev);
 349         struct dax_region *dax_region = dev_dax->region;
 350         struct dax_device *dax_dev = dev_dax->dax_dev;
 351
 352         dax_region_put(dax_region);
 353         put_dax(dax_dev);
 354         kfree(dev_dax);
 355 }
 356
 357 static void unregister_dev_dax(void *dev)
 358 {
 359         struct dev_dax *dev_dax = to_dev_dax(dev);
 360
 361         dev_dbg(dev, "%s\n", __func__);
 362
 363         kill_dev_dax(dev_dax);
 364         device_del(dev);
 365         put_device(dev);
 366 }
 367
 368 struct dev_dax *__devm_create_dev_dax(struct dax_region *dax_region, int id,
 369                 struct dev_pagemap *pgmap, enum dev_dax_subsys subsys)
 370 {
 371         struct device *parent = dax_region->dev;
 372         struct dax_device *dax_dev;
 373         struct dev_dax *dev_dax;
 374         struct inode *inode;
 375         struct device *dev;
 376         int rc = -ENOMEM;
 377
 378         if (id < 0)
 379                 return ERR_PTR(-EINVAL);
 380
 381         dev_dax = kzalloc(sizeof(*dev_dax), GFP_KERNEL);
 382         if (!dev_dax)
 383                 return ERR_PTR(-ENOMEM);
 384
 385         memcpy(&dev_dax->pgmap, pgmap, sizeof(*pgmap));
 386
 387         /*
 388          * No 'host' or dax_operations since there is no access to this
 389          * device outside of mmap of the resulting character device.
 390          */
 391         dax_dev = alloc_dax(dev_dax, NULL, NULL);
 392         if (!dax_dev)
 393                 goto err;
 394
 395         /* a device_dax instance is dead while the driver is not attached */
 396         kill_dax(dax_dev);
 397
 398         /* from here on we're committed to teardown via dax_dev_release() */
 399         dev = &dev_dax->dev;
 400         device_initialize(dev);
 401
 402         dev_dax->dax_dev = dax_dev;
 403         dev_dax->region = dax_region;
 404         dev_dax->target_node = dax_region->target_node;
 405         kref_get(&dax_region->kref);
 406
 407         inode = dax_inode(dax_dev);
 408         dev->devt = inode->i_rdev;
 409         if (subsys == DEV_DAX_BUS)
 410                 dev->bus = &dax_bus_type;
 411         else
 412                 dev->class = dax_class;
 413         dev->parent = parent;
 414         dev->groups = dax_attribute_groups;
 415         dev->release = dev_dax_release;
 416         dev_set_name(dev, "dax%d.%d", dax_region->id, id);
 417
 418         rc = device_add(dev);
 419         if (rc) {
 420                 kill_dev_dax(dev_dax);
 421                 put_device(dev);
 422                 return ERR_PTR(rc);
 423         }
 424
 425         rc = devm_add_action_or_reset(dax_region->dev, unregister_dev_dax, dev);
 426         if (rc)
 427                 return ERR_PTR(rc);
 428
 429         return dev_dax;
 430
 431  err:
 432         kfree(dev_dax);
 433
 434         return ERR_PTR(rc);
 435 }
 436 EXPORT_SYMBOL_GPL(__devm_create_dev_dax);
 437
 438 static int match_always_count;
 439
 440 int __dax_driver_register(struct dax_device_driver *dax_drv,
 441                 struct module *module, const char *mod_name)
 442 {
 443         struct device_driver *drv = &dax_drv->drv;
 444         int rc = 0;
 445
 446         INIT_LIST_HEAD(&dax_drv->ids);
 447         drv->owner = module;
 448         drv->name = mod_name;
 449         drv->mod_name = mod_name;
 450         drv->bus = &dax_bus_type;
 451
 452         /* there can only be one default driver */
 453         mutex_lock(&dax_bus_lock);
 454         match_always_count += dax_drv->match_always;
 455         if (match_always_count > 1) {
 456                 match_always_count--;
 457                 WARN_ON(1);
 458                 rc = -EINVAL;
 459         }
 460         mutex_unlock(&dax_bus_lock);
 461         if (rc)
 462                 return rc;
 463         return driver_register(drv);
 464 }
 465 EXPORT_SYMBOL_GPL(__dax_driver_register);
 466
 467 void dax_driver_unregister(struct dax_device_driver *dax_drv)
 468 {
 469         struct device_driver *drv = &dax_drv->drv;
 470         struct dax_id *dax_id, *_id;
 471
 472         mutex_lock(&dax_bus_lock);
 473         match_always_count -= dax_drv->match_always;
 474         list_for_each_entry_safe(dax_id, _id, &dax_drv->ids, list) {
 475                 list_del(&dax_id->list);
 476                 kfree(dax_id);
 477         }
 478         mutex_unlock(&dax_bus_lock);
 479         driver_unregister(drv);
 480 }
 481 EXPORT_SYMBOL_GPL(dax_driver_unregister);
 482
 483 int __init dax_bus_init(void)
 484 {
 485         int rc;
 486
 487         if (IS_ENABLED(CONFIG_DEV_DAX_PMEM_COMPAT)) {
 488                 dax_class = class_create(THIS_MODULE, "dax");
 489                 if (IS_ERR(dax_class))
 490                         return PTR_ERR(dax_class);
 491         }
 492
 493         rc = bus_register(&dax_bus_type);
 494         if (rc)
 495                 class_destroy(dax_class);
 496         return rc;
 497 }
 498
 499 void __exit dax_bus_exit(void)
 500 {
 501         bus_unregister(&dax_bus_type);
 502         class_destroy(dax_class);
 503 }