drivers/misc/cxl/file.c

   1 /*
   2  * Copyright 2014 IBM Corp.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version
   7  * 2 of the License, or (at your option) any later version.
   8  */
   9
  10 #include <linux/spinlock.h>
  11 #include <linux/module.h>
  12 #include <linux/export.h>
  13 #include <linux/kernel.h>
  14 #include <linux/bitmap.h>
  15 #include <linux/sched.h>
  16 #include <linux/poll.h>
  17 #include <linux/pid.h>
  18 #include <linux/fs.h>
  19 #include <linux/mm.h>
  20 #include <linux/slab.h>
  21 #include <asm/cputable.h>
  22 #include <asm/current.h>
  23 #include <asm/copro.h>
  24
  25 #include "cxl.h"
  26 #include "trace.h"
  27
  28 #define CXL_NUM_MINORS 256 /* Total to reserve */
  29
  30 #define CXL_AFU_MINOR_D(afu) (CXL_CARD_MINOR(afu->adapter) + 1 + (3 * afu->slice))
  31 #define CXL_AFU_MINOR_M(afu) (CXL_AFU_MINOR_D(afu) + 1)
  32 #define CXL_AFU_MINOR_S(afu) (CXL_AFU_MINOR_D(afu) + 2)
  33 #define CXL_AFU_MKDEV_D(afu) MKDEV(MAJOR(cxl_dev), CXL_AFU_MINOR_D(afu))
  34 #define CXL_AFU_MKDEV_M(afu) MKDEV(MAJOR(cxl_dev), CXL_AFU_MINOR_M(afu))
  35 #define CXL_AFU_MKDEV_S(afu) MKDEV(MAJOR(cxl_dev), CXL_AFU_MINOR_S(afu))
  36
  37 #define CXL_DEVT_AFU(dev) ((MINOR(dev) % CXL_DEV_MINORS - 1) / 3)
  38
  39 #define CXL_DEVT_IS_CARD(dev) (MINOR(dev) % CXL_DEV_MINORS == 0)
  40
  41 static dev_t cxl_dev;
  42
  43 static struct class *cxl_class;
  44
  45 static int __afu_open(struct inode *inode, struct file *file, bool master)
  46 {
  47         struct cxl *adapter;
  48         struct cxl_afu *afu;
  49         struct cxl_context *ctx;
  50         int adapter_num = CXL_DEVT_ADAPTER(inode->i_rdev);
  51         int slice = CXL_DEVT_AFU(inode->i_rdev);
  52         int rc = -ENODEV;
  53
  54         pr_devel("afu_open afu%i.%i\n", slice, adapter_num);
  55
  56         if (!(adapter = get_cxl_adapter(adapter_num)))
  57                 return -ENODEV;
  58
  59         if (slice > adapter->slices)
  60                 goto err_put_adapter;
  61
  62         spin_lock(&adapter->afu_list_lock);
  63         if (!(afu = adapter->afu[slice])) {
  64                 spin_unlock(&adapter->afu_list_lock);
  65                 goto err_put_adapter;
  66         }
  67
  68         /*
  69          * taking a ref to the afu so that it doesn't go away
  70          * for rest of the function. This ref is released before
  71          * we return.
  72          */
  73         cxl_afu_get(afu);
  74         spin_unlock(&adapter->afu_list_lock);
  75
  76         if (!afu->current_mode)
  77                 goto err_put_afu;
  78
  79         if (!cxl_ops->link_ok(adapter, afu)) {
  80                 rc = -EIO;
  81                 goto err_put_afu;
  82         }
  83
  84         if (!(ctx = cxl_context_alloc())) {
  85                 rc = -ENOMEM;
  86                 goto err_put_afu;
  87         }
  88
  89         if ((rc = cxl_context_init(ctx, afu, master, inode->i_mapping)))
  90                 goto err_put_afu;
  91
  92         pr_devel("afu_open pe: %i\n", ctx->pe);
  93         file->private_data = ctx;
  94         cxl_ctx_get();
  95
  96         /* indicate success */
  97         rc = 0;
  98
  99 err_put_afu:
 100         /* release the ref taken earlier */
 101         cxl_afu_put(afu);
 102 err_put_adapter:
 103         put_device(&adapter->dev);
 104         return rc;
 105 }
 106
 107 int afu_open(struct inode *inode, struct file *file)
 108 {
 109         return __afu_open(inode, file, false);
 110 }
 111
 112 static int afu_master_open(struct inode *inode, struct file *file)
 113 {
 114         return __afu_open(inode, file, true);
 115 }
 116
 117 int afu_release(struct inode *inode, struct file *file)
 118 {
 119         struct cxl_context *ctx = file->private_data;
 120
 121         pr_devel("%s: closing cxl file descriptor. pe: %i\n",
 122                  __func__, ctx->pe);
 123         cxl_context_detach(ctx);
 124
 125
 126         /*
 127          * Delete the context's mapping pointer, unless it's created by the
 128          * kernel API, in which case leave it so it can be freed by reclaim_ctx()
 129          */
 130         if (!ctx->kernelapi) {
 131                 mutex_lock(&ctx->mapping_lock);
 132                 ctx->mapping = NULL;
 133                 mutex_unlock(&ctx->mapping_lock);
 134         }
 135
 136         /*
 137          * At this this point all bottom halfs have finished and we should be
 138          * getting no more IRQs from the hardware for this context.  Once it's
 139          * removed from the IDR (and RCU synchronised) it's safe to free the
 140          * sstp and context.
 141          */
 142         cxl_context_free(ctx);
 143
 144         return 0;
 145 }
 146
 147 static long afu_ioctl_start_work(struct cxl_context *ctx,
 148                                  struct cxl_ioctl_start_work __user *uwork)
 149 {
 150         struct cxl_ioctl_start_work work;
 151         u64 amr = 0;
 152         int rc;
 153
 154         pr_devel("%s: pe: %i\n", __func__, ctx->pe);
 155
 156         /* Do this outside the status_mutex to avoid a circular dependency with
 157          * the locking in cxl_mmap_fault() */
 158         if (copy_from_user(&work, uwork,
 159                            sizeof(struct cxl_ioctl_start_work))) {
 160                 rc = -EFAULT;
 161                 goto out;
 162         }
 163
 164         mutex_lock(&ctx->status_mutex);
 165         if (ctx->status != OPENED) {
 166                 rc = -EIO;
 167                 goto out;
 168         }
 169
 170         /*
 171          * if any of the reserved fields are set or any of the unused
 172          * flags are set it's invalid
 173          */
 174         if (work.reserved1 || work.reserved2 || work.reserved3 ||
 175             work.reserved4 || work.reserved5 || work.reserved6 ||
 176             (work.flags & ~CXL_START_WORK_ALL)) {
 177                 rc = -EINVAL;
 178                 goto out;
 179         }
 180
 181         if (!(work.flags & CXL_START_WORK_NUM_IRQS))
 182                 work.num_interrupts = ctx->afu->pp_irqs;
 183         else if ((work.num_interrupts < ctx->afu->pp_irqs) ||
 184                  (work.num_interrupts > ctx->afu->irqs_max)) {
 185                 rc =  -EINVAL;
 186                 goto out;
 187         }
 188         if ((rc = afu_register_irqs(ctx, work.num_interrupts)))
 189                 goto out;
 190
 191         if (work.flags & CXL_START_WORK_AMR)
 192                 amr = work.amr & mfspr(SPRN_UAMOR);
 193
 194         ctx->mmio_err_ff = !!(work.flags & CXL_START_WORK_ERR_FF);
 195
 196         /*
 197          * We grab the PID here and not in the file open to allow for the case
 198          * where a process (master, some daemon, etc) has opened the chardev on
 199          * behalf of another process, so the AFU's mm gets bound to the process
 200          * that performs this ioctl and not the process that opened the file.
 201          * Also we grab the PID of the group leader so that if the task that
 202          * has performed the attach operation exits the mm context of the
 203          * process is still accessible.
 204          */
 205         ctx->pid = get_task_pid(current, PIDTYPE_PID);
 206         ctx->glpid = get_task_pid(current->group_leader, PIDTYPE_PID);
 207
 208         trace_cxl_attach(ctx, work.work_element_descriptor, work.num_interrupts, amr);
 209
 210         if ((rc = cxl_ops->attach_process(ctx, false, work.work_element_descriptor,
 211                                                         amr))) {
 212                 afu_release_irqs(ctx, ctx);
 213                 goto out;
 214         }
 215
 216         ctx->status = STARTED;
 217         rc = 0;
 218 out:
 219         mutex_unlock(&ctx->status_mutex);
 220         return rc;
 221 }
 222
 223 static long afu_ioctl_process_element(struct cxl_context *ctx,
 224                                       int __user *upe)
 225 {
 226         pr_devel("%s: pe: %i\n", __func__, ctx->pe);
 227
 228         if (copy_to_user(upe, &ctx->external_pe, sizeof(__u32)))
 229                 return -EFAULT;
 230
 231         return 0;
 232 }
 233
 234 static long afu_ioctl_get_afu_id(struct cxl_context *ctx,
 235                                  struct cxl_afu_id __user *upafuid)
 236 {
 237         struct cxl_afu_id afuid = { 0 };
 238
 239         afuid.card_id = ctx->afu->adapter->adapter_num;
 240         afuid.afu_offset = ctx->afu->slice;
 241         afuid.afu_mode = ctx->afu->current_mode;
 242
 243         /* set the flag bit in case the afu is a slave */
 244         if (ctx->afu->current_mode == CXL_MODE_DIRECTED && !ctx->master)
 245                 afuid.flags |= CXL_AFUID_FLAG_SLAVE;
 246
 247         if (copy_to_user(upafuid, &afuid, sizeof(afuid)))
 248                 return -EFAULT;
 249
 250         return 0;
 251 }
 252
 253 long afu_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 254 {
 255         struct cxl_context *ctx = file->private_data;
 256
 257         if (ctx->status == CLOSED)
 258                 return -EIO;
 259
 260         if (!cxl_ops->link_ok(ctx->afu->adapter, ctx->afu))
 261                 return -EIO;
 262
 263         pr_devel("afu_ioctl\n");
 264         switch (cmd) {
 265         case CXL_IOCTL_START_WORK:
 266                 return afu_ioctl_start_work(ctx, (struct cxl_ioctl_start_work __user *)arg);
 267         case CXL_IOCTL_GET_PROCESS_ELEMENT:
 268                 return afu_ioctl_process_element(ctx, (__u32 __user *)arg);
 269         case CXL_IOCTL_GET_AFU_ID:
 270                 return afu_ioctl_get_afu_id(ctx, (struct cxl_afu_id __user *)
 271                                             arg);
 272         }
 273         return -EINVAL;
 274 }
 275
 276 static long afu_compat_ioctl(struct file *file, unsigned int cmd,
 277                              unsigned long arg)
 278 {
 279         return afu_ioctl(file, cmd, arg);
 280 }
 281
 282 int afu_mmap(struct file *file, struct vm_area_struct *vm)
 283 {
 284         struct cxl_context *ctx = file->private_data;
 285
 286         /* AFU must be started before we can MMIO */
 287         if (ctx->status != STARTED)
 288                 return -EIO;
 289
 290         if (!cxl_ops->link_ok(ctx->afu->adapter, ctx->afu))
 291                 return -EIO;
 292
 293         return cxl_context_iomap(ctx, vm);
 294 }
 295
 296 static inline bool ctx_event_pending(struct cxl_context *ctx)
 297 {
 298         if (ctx->pending_irq || ctx->pending_fault || ctx->pending_afu_err)
 299                 return true;
 300
 301         if (ctx->afu_driver_ops && atomic_read(&ctx->afu_driver_events))
 302                 return true;
 303
 304         return false;
 305 }
 306
 307 unsigned int afu_poll(struct file *file, struct poll_table_struct *poll)
 308 {
 309         struct cxl_context *ctx = file->private_data;
 310         int mask = 0;
 311         unsigned long flags;
 312
 313
 314         poll_wait(file, &ctx->wq, poll);
 315
 316         pr_devel("afu_poll wait done pe: %i\n", ctx->pe);
 317
 318         spin_lock_irqsave(&ctx->lock, flags);
 319         if (ctx_event_pending(ctx))
 320                 mask |= POLLIN | POLLRDNORM;
 321         else if (ctx->status == CLOSED)
 322                 /* Only error on closed when there are no futher events pending
 323                  */
 324                 mask |= POLLERR;
 325         spin_unlock_irqrestore(&ctx->lock, flags);
 326
 327         pr_devel("afu_poll pe: %i returning %#x\n", ctx->pe, mask);
 328
 329         return mask;
 330 }
 331
 332 static ssize_t afu_driver_event_copy(struct cxl_context *ctx,
 333                                      char __user *buf,
 334                                      struct cxl_event *event,
 335                                      struct cxl_event_afu_driver_reserved *pl)
 336 {
 337         /* Check event */
 338         if (!pl) {
 339                 ctx->afu_driver_ops->event_delivered(ctx, pl, -EINVAL);
 340                 return -EFAULT;
 341         }
 342
 343         /* Check event size */
 344         event->header.size += pl->data_size;
 345         if (event->header.size > CXL_READ_MIN_SIZE) {
 346                 ctx->afu_driver_ops->event_delivered(ctx, pl, -EINVAL);
 347                 return -EFAULT;
 348         }
 349
 350         /* Copy event header */
 351         if (copy_to_user(buf, event, sizeof(struct cxl_event_header))) {
 352                 ctx->afu_driver_ops->event_delivered(ctx, pl, -EFAULT);
 353                 return -EFAULT;
 354         }
 355
 356         /* Copy event data */
 357         buf += sizeof(struct cxl_event_header);
 358         if (copy_to_user(buf, &pl->data, pl->data_size)) {
 359                 ctx->afu_driver_ops->event_delivered(ctx, pl, -EFAULT);
 360                 return -EFAULT;
 361         }
 362
 363         ctx->afu_driver_ops->event_delivered(ctx, pl, 0); /* Success */
 364         return event->header.size;
 365 }
 366
 367 ssize_t afu_read(struct file *file, char __user *buf, size_t count,
 368                         loff_t *off)
 369 {
 370         struct cxl_context *ctx = file->private_data;
 371         struct cxl_event_afu_driver_reserved *pl = NULL;
 372         struct cxl_event event;
 373         unsigned long flags;
 374         int rc;
 375         DEFINE_WAIT(wait);
 376
 377         if (!cxl_ops->link_ok(ctx->afu->adapter, ctx->afu))
 378                 return -EIO;
 379
 380         if (count < CXL_READ_MIN_SIZE)
 381                 return -EINVAL;
 382
 383         spin_lock_irqsave(&ctx->lock, flags);
 384
 385         for (;;) {
 386                 prepare_to_wait(&ctx->wq, &wait, TASK_INTERRUPTIBLE);
 387                 if (ctx_event_pending(ctx) || (ctx->status == CLOSED))
 388                         break;
 389
 390                 if (!cxl_ops->link_ok(ctx->afu->adapter, ctx->afu)) {
 391                         rc = -EIO;
 392                         goto out;
 393                 }
 394
 395                 if (file->f_flags & O_NONBLOCK) {
 396                         rc = -EAGAIN;
 397                         goto out;
 398                 }
 399
 400                 if (signal_pending(current)) {
 401                         rc = -ERESTARTSYS;
 402                         goto out;
 403                 }
 404
 405                 spin_unlock_irqrestore(&ctx->lock, flags);
 406                 pr_devel("afu_read going to sleep...\n");
 407                 schedule();
 408                 pr_devel("afu_read woken up\n");
 409                 spin_lock_irqsave(&ctx->lock, flags);
 410         }
 411
 412         finish_wait(&ctx->wq, &wait);
 413
 414         memset(&event, 0, sizeof(event));
 415         event.header.process_element = ctx->pe;
 416         event.header.size = sizeof(struct cxl_event_header);
 417         if (ctx->afu_driver_ops && atomic_read(&ctx->afu_driver_events)) {
 418                 pr_devel("afu_read delivering AFU driver specific event\n");
 419                 pl = ctx->afu_driver_ops->fetch_event(ctx);
 420                 atomic_dec(&ctx->afu_driver_events);
 421                 event.header.type = CXL_EVENT_AFU_DRIVER;
 422         } else if (ctx->pending_irq) {
 423                 pr_devel("afu_read delivering AFU interrupt\n");
 424                 event.header.size += sizeof(struct cxl_event_afu_interrupt);
 425                 event.header.type = CXL_EVENT_AFU_INTERRUPT;
 426                 event.irq.irq = find_first_bit(ctx->irq_bitmap, ctx->irq_count) + 1;
 427                 clear_bit(event.irq.irq - 1, ctx->irq_bitmap);
 428                 if (bitmap_empty(ctx->irq_bitmap, ctx->irq_count))
 429                         ctx->pending_irq = false;
 430         } else if (ctx->pending_fault) {
 431                 pr_devel("afu_read delivering data storage fault\n");
 432                 event.header.size += sizeof(struct cxl_event_data_storage);
 433                 event.header.type = CXL_EVENT_DATA_STORAGE;
 434                 event.fault.addr = ctx->fault_addr;
 435                 event.fault.dsisr = ctx->fault_dsisr;
 436                 ctx->pending_fault = false;
 437         } else if (ctx->pending_afu_err) {
 438                 pr_devel("afu_read delivering afu error\n");
 439                 event.header.size += sizeof(struct cxl_event_afu_error);
 440                 event.header.type = CXL_EVENT_AFU_ERROR;
 441                 event.afu_error.error = ctx->afu_err;
 442                 ctx->pending_afu_err = false;
 443         } else if (ctx->status == CLOSED) {
 444                 pr_devel("afu_read fatal error\n");
 445                 spin_unlock_irqrestore(&ctx->lock, flags);
 446                 return -EIO;
 447         } else
 448                 WARN(1, "afu_read must be buggy\n");
 449
 450         spin_unlock_irqrestore(&ctx->lock, flags);
 451
 452         if (event.header.type == CXL_EVENT_AFU_DRIVER)
 453                 return afu_driver_event_copy(ctx, buf, &event, pl);
 454
 455         if (copy_to_user(buf, &event, event.header.size))
 456                 return -EFAULT;
 457         return event.header.size;
 458
 459 out:
 460         finish_wait(&ctx->wq, &wait);
 461         spin_unlock_irqrestore(&ctx->lock, flags);
 462         return rc;
 463 }
 464
 465 /*
 466  * Note: if this is updated, we need to update api.c to patch the new ones in
 467  * too
 468  */
 469 const struct file_operations afu_fops = {
 470         .owner          = THIS_MODULE,
 471         .open           = afu_open,
 472         .poll           = afu_poll,
 473         .read           = afu_read,
 474         .release        = afu_release,
 475         .unlocked_ioctl = afu_ioctl,
 476         .compat_ioctl   = afu_compat_ioctl,
 477         .mmap           = afu_mmap,
 478 };
 479
 480 static const struct file_operations afu_master_fops = {
 481         .owner          = THIS_MODULE,
 482         .open           = afu_master_open,
 483         .poll           = afu_poll,
 484         .read           = afu_read,
 485         .release        = afu_release,
 486         .unlocked_ioctl = afu_ioctl,
 487         .compat_ioctl   = afu_compat_ioctl,
 488         .mmap           = afu_mmap,
 489 };
 490
 491
 492 static char *cxl_devnode(struct device *dev, umode_t *mode)
 493 {
 494         if (cpu_has_feature(CPU_FTR_HVMODE) &&
 495             CXL_DEVT_IS_CARD(dev->devt)) {
 496                 /*
 497                  * These minor numbers will eventually be used to program the
 498                  * PSL and AFUs once we have dynamic reprogramming support
 499                  */
 500                 return NULL;
 501         }
 502         return kasprintf(GFP_KERNEL, "cxl/%s", dev_name(dev));
 503 }
 504
 505 extern struct class *cxl_class;
 506
 507 static int cxl_add_chardev(struct cxl_afu *afu, dev_t devt, struct cdev *cdev,
 508                            struct device **chardev, char *postfix, char *desc,
 509                            const struct file_operations *fops)
 510 {
 511         struct device *dev;
 512         int rc;
 513
 514         cdev_init(cdev, fops);
 515         if ((rc = cdev_add(cdev, devt, 1))) {
 516                 dev_err(&afu->dev, "Unable to add %s chardev: %i\n", desc, rc);
 517                 return rc;
 518         }
 519
 520         dev = device_create(cxl_class, &afu->dev, devt, afu,
 521                         "afu%i.%i%s", afu->adapter->adapter_num, afu->slice, postfix);
 522         if (IS_ERR(dev)) {
 523                 dev_err(&afu->dev, "Unable to create %s chardev in sysfs: %i\n", desc, rc);
 524                 rc = PTR_ERR(dev);
 525                 goto err;
 526         }
 527
 528         *chardev = dev;
 529
 530         return 0;
 531 err:
 532         cdev_del(cdev);
 533         return rc;
 534 }
 535
 536 int cxl_chardev_d_afu_add(struct cxl_afu *afu)
 537 {
 538         return cxl_add_chardev(afu, CXL_AFU_MKDEV_D(afu), &afu->afu_cdev_d,
 539                                &afu->chardev_d, "d", "dedicated",
 540                                &afu_master_fops); /* Uses master fops */
 541 }
 542
 543 int cxl_chardev_m_afu_add(struct cxl_afu *afu)
 544 {
 545         return cxl_add_chardev(afu, CXL_AFU_MKDEV_M(afu), &afu->afu_cdev_m,
 546                                &afu->chardev_m, "m", "master",
 547                                &afu_master_fops);
 548 }
 549
 550 int cxl_chardev_s_afu_add(struct cxl_afu *afu)
 551 {
 552         return cxl_add_chardev(afu, CXL_AFU_MKDEV_S(afu), &afu->afu_cdev_s,
 553                                &afu->chardev_s, "s", "shared",
 554                                &afu_fops);
 555 }
 556
 557 void cxl_chardev_afu_remove(struct cxl_afu *afu)
 558 {
 559         if (afu->chardev_d) {
 560                 cdev_del(&afu->afu_cdev_d);
 561                 device_unregister(afu->chardev_d);
 562                 afu->chardev_d = NULL;
 563         }
 564         if (afu->chardev_m) {
 565                 cdev_del(&afu->afu_cdev_m);
 566                 device_unregister(afu->chardev_m);
 567                 afu->chardev_m = NULL;
 568         }
 569         if (afu->chardev_s) {
 570                 cdev_del(&afu->afu_cdev_s);
 571                 device_unregister(afu->chardev_s);
 572                 afu->chardev_s = NULL;
 573         }
 574 }
 575
 576 int cxl_register_afu(struct cxl_afu *afu)
 577 {
 578         afu->dev.class = cxl_class;
 579
 580         return device_register(&afu->dev);
 581 }
 582
 583 int cxl_register_adapter(struct cxl *adapter)
 584 {
 585         adapter->dev.class = cxl_class;
 586
 587         /*
 588          * Future: When we support dynamically reprogramming the PSL & AFU we
 589          * will expose the interface to do that via a chardev:
 590          * adapter->dev.devt = CXL_CARD_MKDEV(adapter);
 591          */
 592
 593         return device_register(&adapter->dev);
 594 }
 595
 596 dev_t cxl_get_dev(void)
 597 {
 598         return cxl_dev;
 599 }
 600
 601 int __init cxl_file_init(void)
 602 {
 603         int rc;
 604
 605         /*
 606          * If these change we really need to update API.  Either change some
 607          * flags or update API version number CXL_API_VERSION.
 608          */
 609         BUILD_BUG_ON(CXL_API_VERSION != 3);
 610         BUILD_BUG_ON(sizeof(struct cxl_ioctl_start_work) != 64);
 611         BUILD_BUG_ON(sizeof(struct cxl_event_header) != 8);
 612         BUILD_BUG_ON(sizeof(struct cxl_event_afu_interrupt) != 8);
 613         BUILD_BUG_ON(sizeof(struct cxl_event_data_storage) != 32);
 614         BUILD_BUG_ON(sizeof(struct cxl_event_afu_error) != 16);
 615
 616         if ((rc = alloc_chrdev_region(&cxl_dev, 0, CXL_NUM_MINORS, "cxl"))) {
 617                 pr_err("Unable to allocate CXL major number: %i\n", rc);
 618                 return rc;
 619         }
 620
 621         pr_devel("CXL device allocated, MAJOR %i\n", MAJOR(cxl_dev));
 622
 623         cxl_class = class_create(THIS_MODULE, "cxl");
 624         if (IS_ERR(cxl_class)) {
 625                 pr_err("Unable to create CXL class\n");
 626                 rc = PTR_ERR(cxl_class);
 627                 goto err;
 628         }
 629         cxl_class->devnode = cxl_devnode;
 630
 631         return 0;
 632
 633 err:
 634         unregister_chrdev_region(cxl_dev, CXL_NUM_MINORS);
 635         return rc;
 636 }
 637
 638 void cxl_file_exit(void)
 639 {
 640         unregister_chrdev_region(cxl_dev, CXL_NUM_MINORS);
 641         class_destroy(cxl_class);
 642 }