drivers/s390/cio/css.c

   1 /*
   2  *  drivers/s390/cio/css.c
   3  *  driver for channel subsystem
   4  *
   5  *    Copyright (C) 2002 IBM Deutschland Entwicklung GmbH,
   6  *                       IBM Corporation
   7  *    Author(s): Arnd Bergmann (arndb@de.ibm.com)
   8  *               Cornelia Huck (cornelia.huck@de.ibm.com)
   9  */
  10 #include <linux/module.h>
  11 #include <linux/init.h>
  12 #include <linux/device.h>
  13 #include <linux/slab.h>
  14 #include <linux/errno.h>
  15 #include <linux/list.h>
  16
  17 #include "css.h"
  18 #include "cio.h"
  19 #include "cio_debug.h"
  20 #include "ioasm.h"
  21 #include "chsc.h"
  22 #include "device.h"
  23
  24 int need_rescan = 0;
  25 int css_init_done = 0;
  26 static int need_reprobe = 0;
  27 static int max_ssid = 0;
  28
  29 struct channel_subsystem *css[__MAX_CSSID + 1];
  30
  31 int css_characteristics_avail = 0;
  32
  33 inline int
  34 for_each_subchannel(int(*fn)(struct subchannel_id, void *), void *data)
  35 {
  36         struct subchannel_id schid;
  37         int ret;
  38
  39         init_subchannel_id(&schid);
  40         ret = -ENODEV;
  41         do {
  42                 do {
  43                         ret = fn(schid, data);
  44                         if (ret)
  45                                 break;
  46                 } while (schid.sch_no++ < __MAX_SUBCHANNEL);
  47                 schid.sch_no = 0;
  48         } while (schid.ssid++ < max_ssid);
  49         return ret;
  50 }
  51
  52 static struct subchannel *
  53 css_alloc_subchannel(struct subchannel_id schid)
  54 {
  55         struct subchannel *sch;
  56         int ret;
  57
  58         sch = kmalloc (sizeof (*sch), GFP_KERNEL | GFP_DMA);
  59         if (sch == NULL)
  60                 return ERR_PTR(-ENOMEM);
  61         ret = cio_validate_subchannel (sch, schid);
  62         if (ret < 0) {
  63                 kfree(sch);
  64                 return ERR_PTR(ret);
  65         }
  66
  67         if (sch->st != SUBCHANNEL_TYPE_IO) {
  68                 /* For now we ignore all non-io subchannels. */
  69                 kfree(sch);
  70                 return ERR_PTR(-EINVAL);
  71         }
  72
  73         /*
  74          * Set intparm to subchannel address.
  75          * This is fine even on 64bit since the subchannel is always located
  76          * under 2G.
  77          */
  78         sch->schib.pmcw.intparm = (__u32)(unsigned long)sch;
  79         ret = cio_modify(sch);
  80         if (ret) {
  81                 kfree(sch);
  82                 return ERR_PTR(ret);
  83         }
  84         return sch;
  85 }
  86
  87 static void
  88 css_free_subchannel(struct subchannel *sch)
  89 {
  90         if (sch) {
  91                 /* Reset intparm to zeroes. */
  92                 sch->schib.pmcw.intparm = 0;
  93                 cio_modify(sch);
  94                 kfree(sch);
  95         }
  96
  97 }
  98
  99 static void
 100 css_subchannel_release(struct device *dev)
 101 {
 102         struct subchannel *sch;
 103
 104         sch = to_subchannel(dev);
 105         if (!cio_is_console(sch->schid))
 106                 kfree(sch);
 107 }
 108
 109 extern int css_get_ssd_info(struct subchannel *sch);
 110
 111
 112 int css_sch_device_register(struct subchannel *sch)
 113 {
 114         int ret;
 115
 116         mutex_lock(&sch->reg_mutex);
 117         ret = device_register(&sch->dev);
 118         mutex_unlock(&sch->reg_mutex);
 119         return ret;
 120 }
 121
 122 void css_sch_device_unregister(struct subchannel *sch)
 123 {
 124         mutex_lock(&sch->reg_mutex);
 125         device_unregister(&sch->dev);
 126         mutex_unlock(&sch->reg_mutex);
 127 }
 128
 129 static int
 130 css_register_subchannel(struct subchannel *sch)
 131 {
 132         int ret;
 133
 134         /* Initialize the subchannel structure */
 135         sch->dev.parent = &css[0]->device;
 136         sch->dev.bus = &css_bus_type;
 137         sch->dev.release = &css_subchannel_release;
 138
 139         /* make it known to the system */
 140         ret = css_sch_device_register(sch);
 141         if (ret)
 142                 printk (KERN_WARNING "%s: could not register %s\n",
 143                         __func__, sch->dev.bus_id);
 144         else
 145                 css_get_ssd_info(sch);
 146         return ret;
 147 }
 148
 149 int
 150 css_probe_device(struct subchannel_id schid)
 151 {
 152         int ret;
 153         struct subchannel *sch;
 154
 155         sch = css_alloc_subchannel(schid);
 156         if (IS_ERR(sch))
 157                 return PTR_ERR(sch);
 158         ret = css_register_subchannel(sch);
 159         if (ret)
 160                 css_free_subchannel(sch);
 161         return ret;
 162 }
 163
 164 static int
 165 check_subchannel(struct device * dev, void * data)
 166 {
 167         struct subchannel *sch;
 168         struct subchannel_id *schid = data;
 169
 170         sch = to_subchannel(dev);
 171         return schid_equal(&sch->schid, schid);
 172 }
 173
 174 struct subchannel *
 175 get_subchannel_by_schid(struct subchannel_id schid)
 176 {
 177         struct device *dev;
 178
 179         dev = bus_find_device(&css_bus_type, NULL,
 180                               (void *)&schid, check_subchannel);
 181
 182         return dev ? to_subchannel(dev) : NULL;
 183 }
 184
 185
 186 static inline int
 187 css_get_subchannel_status(struct subchannel *sch, struct subchannel_id schid)
 188 {
 189         struct schib schib;
 190         int cc;
 191
 192         cc = stsch(schid, &schib);
 193         if (cc)
 194                 return CIO_GONE;
 195         if (!schib.pmcw.dnv)
 196                 return CIO_GONE;
 197         if (sch && sch->schib.pmcw.dnv &&
 198             (schib.pmcw.dev != sch->schib.pmcw.dev))
 199                 return CIO_REVALIDATE;
 200         if (sch && !sch->lpm)
 201                 return CIO_NO_PATH;
 202         return CIO_OPER;
 203 }
 204
 205 static int
 206 css_evaluate_subchannel(struct subchannel_id schid, int slow)
 207 {
 208         int event, ret, disc;
 209         struct subchannel *sch;
 210         unsigned long flags;
 211
 212         sch = get_subchannel_by_schid(schid);
 213         disc = sch ? device_is_disconnected(sch) : 0;
 214         if (disc && slow) {
 215                 if (sch)
 216                         put_device(&sch->dev);
 217                 return 0; /* Already processed. */
 218         }
 219         /*
 220          * We've got a machine check, so running I/O won't get an interrupt.
 221          * Kill any pending timers.
 222          */
 223         if (sch)
 224                 device_kill_pending_timer(sch);
 225         if (!disc && !slow) {
 226                 if (sch)
 227                         put_device(&sch->dev);
 228                 return -EAGAIN; /* Will be done on the slow path. */
 229         }
 230         event = css_get_subchannel_status(sch, schid);
 231         CIO_MSG_EVENT(4, "Evaluating schid 0.%x.%04x, event %d, %s, %s path.\n",
 232                       schid.ssid, schid.sch_no, event,
 233                       sch?(disc?"disconnected":"normal"):"unknown",
 234                       slow?"slow":"fast");
 235         switch (event) {
 236         case CIO_NO_PATH:
 237         case CIO_GONE:
 238                 if (!sch) {
 239                         /* Never used this subchannel. Ignore. */
 240                         ret = 0;
 241                         break;
 242                 }
 243                 if (disc && (event == CIO_NO_PATH)) {
 244                         /*
 245                          * Uargh, hack again. Because we don't get a machine
 246                          * check on configure on, our path bookkeeping can
 247                          * be out of date here (it's fine while we only do
 248                          * logical varying or get chsc machine checks). We
 249                          * need to force reprobing or we might miss devices
 250                          * coming operational again. It won't do harm in real
 251                          * no path situations.
 252                          */
 253                         spin_lock_irqsave(&sch->lock, flags);
 254                         device_trigger_reprobe(sch);
 255                         spin_unlock_irqrestore(&sch->lock, flags);
 256                         ret = 0;
 257                         break;
 258                 }
 259                 if (sch->driver && sch->driver->notify &&
 260                     sch->driver->notify(&sch->dev, event)) {
 261                         cio_disable_subchannel(sch);
 262                         device_set_disconnected(sch);
 263                         ret = 0;
 264                         break;
 265                 }
 266                 /*
 267                  * Unregister subchannel.
 268                  * The device will be killed automatically.
 269                  */
 270                 cio_disable_subchannel(sch);
 271                 css_sch_device_unregister(sch);
 272                 /* Reset intparm to zeroes. */
 273                 sch->schib.pmcw.intparm = 0;
 274                 cio_modify(sch);
 275                 put_device(&sch->dev);
 276                 ret = 0;
 277                 break;
 278         case CIO_REVALIDATE:
 279                 /*
 280                  * Revalidation machine check. Sick.
 281                  * We don't notify the driver since we have to throw the device
 282                  * away in any case.
 283                  */
 284                 if (!disc) {
 285                         css_sch_device_unregister(sch);
 286                         /* Reset intparm to zeroes. */
 287                         sch->schib.pmcw.intparm = 0;
 288                         cio_modify(sch);
 289                         put_device(&sch->dev);
 290                         ret = css_probe_device(schid);
 291                 } else {
 292                         /*
 293                          * We can't immediately deregister the disconnected
 294                          * device since it might block.
 295                          */
 296                         spin_lock_irqsave(&sch->lock, flags);
 297                         device_trigger_reprobe(sch);
 298                         spin_unlock_irqrestore(&sch->lock, flags);
 299                         ret = 0;
 300                 }
 301                 break;
 302         case CIO_OPER:
 303                 if (disc) {
 304                         spin_lock_irqsave(&sch->lock, flags);
 305                         /* Get device operational again. */
 306                         device_trigger_reprobe(sch);
 307                         spin_unlock_irqrestore(&sch->lock, flags);
 308                 }
 309                 ret = sch ? 0 : css_probe_device(schid);
 310                 break;
 311         default:
 312                 BUG();
 313                 ret = 0;
 314         }
 315         return ret;
 316 }
 317
 318 static int
 319 css_rescan_devices(struct subchannel_id schid, void *data)
 320 {
 321         return css_evaluate_subchannel(schid, 1);
 322 }
 323
 324 struct slow_subchannel {
 325         struct list_head slow_list;
 326         struct subchannel_id schid;
 327 };
 328
 329 static LIST_HEAD(slow_subchannels_head);
 330 static DEFINE_SPINLOCK(slow_subchannel_lock);
 331
 332 static void
 333 css_trigger_slow_path(void)
 334 {
 335         CIO_TRACE_EVENT(4, "slowpath");
 336
 337         if (need_rescan) {
 338                 need_rescan = 0;
 339                 for_each_subchannel(css_rescan_devices, NULL);
 340                 return;
 341         }
 342
 343         spin_lock_irq(&slow_subchannel_lock);
 344         while (!list_empty(&slow_subchannels_head)) {
 345                 struct slow_subchannel *slow_sch =
 346                         list_entry(slow_subchannels_head.next,
 347                                    struct slow_subchannel, slow_list);
 348
 349                 list_del_init(slow_subchannels_head.next);
 350                 spin_unlock_irq(&slow_subchannel_lock);
 351                 css_evaluate_subchannel(slow_sch->schid, 1);
 352                 spin_lock_irq(&slow_subchannel_lock);
 353                 kfree(slow_sch);
 354         }
 355         spin_unlock_irq(&slow_subchannel_lock);
 356 }
 357
 358 typedef void (*workfunc)(void *);
 359 DECLARE_WORK(slow_path_work, (workfunc)css_trigger_slow_path, NULL);
 360 struct workqueue_struct *slow_path_wq;
 361
 362 /* Reprobe subchannel if unregistered. */
 363 static int reprobe_subchannel(struct subchannel_id schid, void *data)
 364 {
 365         struct subchannel *sch;
 366         int ret;
 367
 368         CIO_DEBUG(KERN_INFO, 6, "cio: reprobe 0.%x.%04x\n",
 369                   schid.ssid, schid.sch_no);
 370         if (need_reprobe)
 371                 return -EAGAIN;
 372
 373         sch = get_subchannel_by_schid(schid);
 374         if (sch) {
 375                 /* Already known. */
 376                 put_device(&sch->dev);
 377                 return 0;
 378         }
 379
 380         ret = css_probe_device(schid);
 381         switch (ret) {
 382         case 0:
 383                 break;
 384         case -ENXIO:
 385         case -ENOMEM:
 386                 /* These should abort looping */
 387                 break;
 388         default:
 389                 ret = 0;
 390         }
 391
 392         return ret;
 393 }
 394
 395 /* Work function used to reprobe all unregistered subchannels. */
 396 static void reprobe_all(void *data)
 397 {
 398         int ret;
 399
 400         CIO_MSG_EVENT(2, "reprobe start\n");
 401
 402         need_reprobe = 0;
 403         /* Make sure initial subchannel scan is done. */
 404         wait_event(ccw_device_init_wq,
 405                    atomic_read(&ccw_device_init_count) == 0);
 406         ret = for_each_subchannel(reprobe_subchannel, NULL);
 407
 408         CIO_MSG_EVENT(2, "reprobe done (rc=%d, need_reprobe=%d)\n", ret,
 409                       need_reprobe);
 410 }
 411
 412 DECLARE_WORK(css_reprobe_work, reprobe_all, NULL);
 413
 414 /* Schedule reprobing of all unregistered subchannels. */
 415 void css_schedule_reprobe(void)
 416 {
 417         need_reprobe = 1;
 418         queue_work(ccw_device_work, &css_reprobe_work);
 419 }
 420
 421 EXPORT_SYMBOL_GPL(css_schedule_reprobe);
 422
 423 /*
 424  * Rescan for new devices. FIXME: This is slow.
 425  * This function is called when we have lost CRWs due to overflows and we have
 426  * to do subchannel housekeeping.
 427  */
 428 void
 429 css_reiterate_subchannels(void)
 430 {
 431         css_clear_subchannel_slow_list();
 432         need_rescan = 1;
 433 }
 434
 435 /*
 436  * Called from the machine check handler for subchannel report words.
 437  */
 438 int
 439 css_process_crw(int rsid1, int rsid2)
 440 {
 441         int ret;
 442         struct subchannel_id mchk_schid;
 443
 444         CIO_CRW_EVENT(2, "source is subchannel %04X, subsystem id %x\n",
 445                       rsid1, rsid2);
 446
 447         if (need_rescan)
 448                 /* We need to iterate all subchannels anyway. */
 449                 return -EAGAIN;
 450
 451         init_subchannel_id(&mchk_schid);
 452         mchk_schid.sch_no = rsid1;
 453         if (rsid2 != 0)
 454                 mchk_schid.ssid = (rsid2 >> 8) & 3;
 455
 456         /*
 457          * Since we are always presented with IPI in the CRW, we have to
 458          * use stsch() to find out if the subchannel in question has come
 459          * or gone.
 460          */
 461         ret = css_evaluate_subchannel(mchk_schid, 0);
 462         if (ret == -EAGAIN) {
 463                 if (css_enqueue_subchannel_slow(mchk_schid)) {
 464                         css_clear_subchannel_slow_list();
 465                         need_rescan = 1;
 466                 }
 467         }
 468         return ret;
 469 }
 470
 471 static int __init
 472 __init_channel_subsystem(struct subchannel_id schid, void *data)
 473 {
 474         struct subchannel *sch;
 475         int ret;
 476
 477         if (cio_is_console(schid))
 478                 sch = cio_get_console_subchannel();
 479         else {
 480                 sch = css_alloc_subchannel(schid);
 481                 if (IS_ERR(sch))
 482                         ret = PTR_ERR(sch);
 483                 else
 484                         ret = 0;
 485                 switch (ret) {
 486                 case 0:
 487                         break;
 488                 case -ENOMEM:
 489                         panic("Out of memory in init_channel_subsystem\n");
 490                 /* -ENXIO: no more subchannels. */
 491                 case -ENXIO:
 492                         return ret;
 493                 /* -EIO: this subchannel set not supported. */
 494                 case -EIO:
 495                         return ret;
 496                 default:
 497                         return 0;
 498                 }
 499         }
 500         /*
 501          * We register ALL valid subchannels in ioinfo, even those
 502          * that have been present before init_channel_subsystem.
 503          * These subchannels can't have been registered yet (kmalloc
 504          * not working) so we do it now. This is true e.g. for the
 505          * console subchannel.
 506          */
 507         css_register_subchannel(sch);
 508         return 0;
 509 }
 510
 511 static void __init
 512 css_generate_pgid(struct channel_subsystem *css, u32 tod_high)
 513 {
 514         if (css_characteristics_avail && css_general_characteristics.mcss) {
 515                 css->global_pgid.pgid_high.ext_cssid.version = 0x80;
 516                 css->global_pgid.pgid_high.ext_cssid.cssid = css->cssid;
 517         } else {
 518 #ifdef CONFIG_SMP
 519                 css->global_pgid.pgid_high.cpu_addr = hard_smp_processor_id();
 520 #else
 521                 css->global_pgid.pgid_high.cpu_addr = 0;
 522 #endif
 523         }
 524         css->global_pgid.cpu_id = ((cpuid_t *) __LC_CPUID)->ident;
 525         css->global_pgid.cpu_model = ((cpuid_t *) __LC_CPUID)->machine;
 526         css->global_pgid.tod_high = tod_high;
 527
 528 }
 529
 530 static void
 531 channel_subsystem_release(struct device *dev)
 532 {
 533         struct channel_subsystem *css;
 534
 535         css = to_css(dev);
 536         mutex_destroy(&css->mutex);
 537         kfree(css);
 538 }
 539
 540 static ssize_t
 541 css_cm_enable_show(struct device *dev, struct device_attribute *attr,
 542                    char *buf)
 543 {
 544         struct channel_subsystem *css = to_css(dev);
 545
 546         if (!css)
 547                 return 0;
 548         return sprintf(buf, "%x\n", css->cm_enabled);
 549 }
 550
 551 static ssize_t
 552 css_cm_enable_store(struct device *dev, struct device_attribute *attr,
 553                     const char *buf, size_t count)
 554 {
 555         struct channel_subsystem *css = to_css(dev);
 556         int ret;
 557
 558         switch (buf[0]) {
 559         case '0':
 560                 ret = css->cm_enabled ? chsc_secm(css, 0) : 0;
 561                 break;
 562         case '1':
 563                 ret = css->cm_enabled ? 0 : chsc_secm(css, 1);
 564                 break;
 565         default:
 566                 ret = -EINVAL;
 567         }
 568         return ret < 0 ? ret : count;
 569 }
 570
 571 static DEVICE_ATTR(cm_enable, 0644, css_cm_enable_show, css_cm_enable_store);
 572
 573 static inline void __init
 574 setup_css(int nr)
 575 {
 576         u32 tod_high;
 577
 578         memset(css[nr], 0, sizeof(struct channel_subsystem));
 579         mutex_init(&css[nr]->mutex);
 580         css[nr]->valid = 1;
 581         css[nr]->cssid = nr;
 582         sprintf(css[nr]->device.bus_id, "css%x", nr);
 583         css[nr]->device.release = channel_subsystem_release;
 584         tod_high = (u32) (get_clock() >> 32);
 585         css_generate_pgid(css[nr], tod_high);
 586 }
 587
 588 /*
 589  * Now that the driver core is running, we can setup our channel subsystem.
 590  * The struct subchannel's are created during probing (except for the
 591  * static console subchannel).
 592  */
 593 static int __init
 594 init_channel_subsystem (void)
 595 {
 596         int ret, i;
 597
 598         if (chsc_determine_css_characteristics() == 0)
 599                 css_characteristics_avail = 1;
 600
 601         if ((ret = bus_register(&css_bus_type)))
 602                 goto out;
 603
 604         /* Try to enable MSS. */
 605         ret = chsc_enable_facility(CHSC_SDA_OC_MSS);
 606         switch (ret) {
 607         case 0: /* Success. */
 608                 max_ssid = __MAX_SSID;
 609                 break;
 610         case -ENOMEM:
 611                 goto out_bus;
 612         default:
 613                 max_ssid = 0;
 614         }
 615         /* Setup css structure. */
 616         for (i = 0; i <= __MAX_CSSID; i++) {
 617                 css[i] = kmalloc(sizeof(struct channel_subsystem), GFP_KERNEL);
 618                 if (!css[i]) {
 619                         ret = -ENOMEM;
 620                         goto out_unregister;
 621                 }
 622                 setup_css(i);
 623                 ret = device_register(&css[i]->device);
 624                 if (ret)
 625                         goto out_free;
 626                 if (css_characteristics_avail &&
 627                     css_chsc_characteristics.secm) {
 628                         ret = device_create_file(&css[i]->device,
 629                                                  &dev_attr_cm_enable);
 630                         if (ret)
 631                                 goto out_device;
 632                 }
 633         }
 634         css_init_done = 1;
 635
 636         ctl_set_bit(6, 28);
 637
 638         for_each_subchannel(__init_channel_subsystem, NULL);
 639         return 0;
 640 out_device:
 641         device_unregister(&css[i]->device);
 642 out_free:
 643         kfree(css[i]);
 644 out_unregister:
 645         while (i > 0) {
 646                 i--;
 647                 if (css_characteristics_avail && css_chsc_characteristics.secm)
 648                         device_remove_file(&css[i]->device,
 649                                            &dev_attr_cm_enable);
 650                 device_unregister(&css[i]->device);
 651         }
 652 out_bus:
 653         bus_unregister(&css_bus_type);
 654 out:
 655         return ret;
 656 }
 657
 658 /*
 659  * find a driver for a subchannel. They identify by the subchannel
 660  * type with the exception that the console subchannel driver has its own
 661  * subchannel type although the device is an i/o subchannel
 662  */
 663 static int
 664 css_bus_match (struct device *dev, struct device_driver *drv)
 665 {
 666         struct subchannel *sch = container_of (dev, struct subchannel, dev);
 667         struct css_driver *driver = container_of (drv, struct css_driver, drv);
 668
 669         if (sch->st == driver->subchannel_type)
 670                 return 1;
 671
 672         return 0;
 673 }
 674
 675 static int
 676 css_probe (struct device *dev)
 677 {
 678         struct subchannel *sch;
 679
 680         sch = to_subchannel(dev);
 681         sch->driver = container_of (dev->driver, struct css_driver, drv);
 682         return (sch->driver->probe ? sch->driver->probe(sch) : 0);
 683 }
 684
 685 static int
 686 css_remove (struct device *dev)
 687 {
 688         struct subchannel *sch;
 689
 690         sch = to_subchannel(dev);
 691         return (sch->driver->remove ? sch->driver->remove(sch) : 0);
 692 }
 693
 694 static void
 695 css_shutdown (struct device *dev)
 696 {
 697         struct subchannel *sch;
 698
 699         sch = to_subchannel(dev);
 700         if (sch->driver->shutdown)
 701                 sch->driver->shutdown(sch);
 702 }
 703
 704 struct bus_type css_bus_type = {
 705         .name     = "css",
 706         .match    = css_bus_match,
 707         .probe    = css_probe,
 708         .remove   = css_remove,
 709         .shutdown = css_shutdown,
 710 };
 711
 712 subsys_initcall(init_channel_subsystem);
 713
 714 int
 715 css_enqueue_subchannel_slow(struct subchannel_id schid)
 716 {
 717         struct slow_subchannel *new_slow_sch;
 718         unsigned long flags;
 719
 720         new_slow_sch = kzalloc(sizeof(struct slow_subchannel), GFP_ATOMIC);
 721         if (!new_slow_sch)
 722                 return -ENOMEM;
 723         new_slow_sch->schid = schid;
 724         spin_lock_irqsave(&slow_subchannel_lock, flags);
 725         list_add_tail(&new_slow_sch->slow_list, &slow_subchannels_head);
 726         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 727         return 0;
 728 }
 729
 730 void
 731 css_clear_subchannel_slow_list(void)
 732 {
 733         unsigned long flags;
 734
 735         spin_lock_irqsave(&slow_subchannel_lock, flags);
 736         while (!list_empty(&slow_subchannels_head)) {
 737                 struct slow_subchannel *slow_sch =
 738                         list_entry(slow_subchannels_head.next,
 739                                    struct slow_subchannel, slow_list);
 740
 741                 list_del_init(slow_subchannels_head.next);
 742                 kfree(slow_sch);
 743         }
 744         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 745 }
 746
 747
 748
 749 int
 750 css_slow_subchannels_exist(void)
 751 {
 752         return (!list_empty(&slow_subchannels_head));
 753 }
 754
 755 MODULE_LICENSE("GPL");
 756 EXPORT_SYMBOL(css_bus_type);
 757 EXPORT_SYMBOL_GPL(css_characteristics_avail);