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   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->lock);
  95                 kfree(sch);
  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->lock);
 107                 kfree(sch);
 108         }
 109 }
 110
 111 extern int css_get_ssd_info(struct subchannel *sch);
 112
 113
 114 int css_sch_device_register(struct subchannel *sch)
 115 {
 116         int ret;
 117
 118         mutex_lock(&sch->reg_mutex);
 119         ret = device_register(&sch->dev);
 120         mutex_unlock(&sch->reg_mutex);
 121         return ret;
 122 }
 123
 124 void css_sch_device_unregister(struct subchannel *sch)
 125 {
 126         mutex_lock(&sch->reg_mutex);
 127         device_unregister(&sch->dev);
 128         mutex_unlock(&sch->reg_mutex);
 129 }
 130
 131 static int
 132 css_register_subchannel(struct subchannel *sch)
 133 {
 134         int ret;
 135
 136         /* Initialize the subchannel structure */
 137         sch->dev.parent = &css[0]->device;
 138         sch->dev.bus = &css_bus_type;
 139         sch->dev.release = &css_subchannel_release;
 140
 141         /* make it known to the system */
 142         ret = css_sch_device_register(sch);
 143         if (ret) {
 144                 printk (KERN_WARNING "%s: could not register %s\n",
 145                         __func__, sch->dev.bus_id);
 146                 return ret;
 147         }
 148         css_get_ssd_info(sch);
 149         ret = subchannel_add_files(&sch->dev);
 150         if (ret)
 151                 printk(KERN_WARNING "%s: could not add attributes to %s\n",
 152                        __func__, sch->dev.bus_id);
 153         return ret;
 154 }
 155
 156 int
 157 css_probe_device(struct subchannel_id schid)
 158 {
 159         int ret;
 160         struct subchannel *sch;
 161
 162         sch = css_alloc_subchannel(schid);
 163         if (IS_ERR(sch))
 164                 return PTR_ERR(sch);
 165         ret = css_register_subchannel(sch);
 166         if (ret)
 167                 css_free_subchannel(sch);
 168         return ret;
 169 }
 170
 171 static int
 172 check_subchannel(struct device * dev, void * data)
 173 {
 174         struct subchannel *sch;
 175         struct subchannel_id *schid = data;
 176
 177         sch = to_subchannel(dev);
 178         return schid_equal(&sch->schid, schid);
 179 }
 180
 181 struct subchannel *
 182 get_subchannel_by_schid(struct subchannel_id schid)
 183 {
 184         struct device *dev;
 185
 186         dev = bus_find_device(&css_bus_type, NULL,
 187                               &schid, check_subchannel);
 188
 189         return dev ? to_subchannel(dev) : NULL;
 190 }
 191
 192 static inline int css_get_subchannel_status(struct subchannel *sch)
 193 {
 194         struct schib schib;
 195
 196         if (stsch(sch->schid, &schib) || !schib.pmcw.dnv)
 197                 return CIO_GONE;
 198         if (sch->schib.pmcw.dnv && (schib.pmcw.dev != sch->schib.pmcw.dev))
 199                 return CIO_REVALIDATE;
 200         if (!sch->lpm)
 201                 return CIO_NO_PATH;
 202         return CIO_OPER;
 203 }
 204
 205 static int css_evaluate_known_subchannel(struct subchannel *sch, int slow)
 206 {
 207         int event, ret, disc;
 208         unsigned long flags;
 209         enum { NONE, UNREGISTER, UNREGISTER_PROBE, REPROBE } action;
 210
 211         spin_lock_irqsave(sch->lock, flags);
 212         disc = device_is_disconnected(sch);
 213         if (disc && slow) {
 214                 /* Disconnected devices are evaluated directly only.*/
 215                 spin_unlock_irqrestore(sch->lock, flags);
 216                 return 0;
 217         }
 218         /* No interrupt after machine check - kill pending timers. */
 219         device_kill_pending_timer(sch);
 220         if (!disc && !slow) {
 221                 /* Non-disconnected devices are evaluated on the slow path. */
 222                 spin_unlock_irqrestore(sch->lock, flags);
 223                 return -EAGAIN;
 224         }
 225         event = css_get_subchannel_status(sch);
 226         CIO_MSG_EVENT(4, "Evaluating schid 0.%x.%04x, event %d, %s, %s path.\n",
 227                       sch->schid.ssid, sch->schid.sch_no, event,
 228                       disc ? "disconnected" : "normal",
 229                       slow ? "slow" : "fast");
 230         /* Analyze subchannel status. */
 231         action = NONE;
 232         switch (event) {
 233         case CIO_NO_PATH:
 234                 if (disc) {
 235                         /* Check if paths have become available. */
 236                         action = REPROBE;
 237                         break;
 238                 }
 239                 /* fall through */
 240         case CIO_GONE:
 241                 /* Prevent unwanted effects when opening lock. */
 242                 cio_disable_subchannel(sch);
 243                 device_set_disconnected(sch);
 244                 /* Ask driver what to do with device. */
 245                 action = UNREGISTER;
 246                 if (sch->driver && sch->driver->notify) {
 247                         spin_unlock_irqrestore(sch->lock, flags);
 248                         ret = sch->driver->notify(&sch->dev, event);
 249                         spin_lock_irqsave(sch->lock, flags);
 250                         if (ret)
 251                                 action = NONE;
 252                 }
 253                 break;
 254         case CIO_REVALIDATE:
 255                 /* Device will be removed, so no notify necessary. */
 256                 if (disc)
 257                         /* Reprobe because immediate unregister might block. */
 258                         action = REPROBE;
 259                 else
 260                         action = UNREGISTER_PROBE;
 261                 break;
 262         case CIO_OPER:
 263                 if (disc)
 264                         /* Get device operational again. */
 265                         action = REPROBE;
 266                 break;
 267         }
 268         /* Perform action. */
 269         ret = 0;
 270         switch (action) {
 271         case UNREGISTER:
 272         case UNREGISTER_PROBE:
 273                 /* Unregister device (will use subchannel lock). */
 274                 spin_unlock_irqrestore(sch->lock, flags);
 275                 css_sch_device_unregister(sch);
 276                 spin_lock_irqsave(sch->lock, flags);
 277
 278                 /* Reset intparm to zeroes. */
 279                 sch->schib.pmcw.intparm = 0;
 280                 cio_modify(sch);
 281                 break;
 282         case REPROBE:
 283                 device_trigger_reprobe(sch);
 284                 break;
 285         default:
 286                 break;
 287         }
 288         spin_unlock_irqrestore(sch->lock, flags);
 289         /* Probe if necessary. */
 290         if (action == UNREGISTER_PROBE)
 291                 ret = css_probe_device(sch->schid);
 292
 293         return ret;
 294 }
 295
 296 static int css_evaluate_new_subchannel(struct subchannel_id schid, int slow)
 297 {
 298         struct schib schib;
 299
 300         if (!slow) {
 301                 /* Will be done on the slow path. */
 302                 return -EAGAIN;
 303         }
 304         if (stsch(schid, &schib) || !schib.pmcw.dnv) {
 305                 /* Unusable - ignore. */
 306                 return 0;
 307         }
 308         CIO_MSG_EVENT(4, "Evaluating schid 0.%x.%04x, event %d, unknown, "
 309                          "slow path.\n", schid.ssid, schid.sch_no, CIO_OPER);
 310
 311         return css_probe_device(schid);
 312 }
 313
 314 static int css_evaluate_subchannel(struct subchannel_id schid, int slow)
 315 {
 316         struct subchannel *sch;
 317         int ret;
 318
 319         sch = get_subchannel_by_schid(schid);
 320         if (sch) {
 321                 ret = css_evaluate_known_subchannel(sch, slow);
 322                 put_device(&sch->dev);
 323         } else
 324                 ret = css_evaluate_new_subchannel(schid, slow);
 325
 326         return ret;
 327 }
 328
 329 static int
 330 css_rescan_devices(struct subchannel_id schid, void *data)
 331 {
 332         return css_evaluate_subchannel(schid, 1);
 333 }
 334
 335 struct slow_subchannel {
 336         struct list_head slow_list;
 337         struct subchannel_id schid;
 338 };
 339
 340 static LIST_HEAD(slow_subchannels_head);
 341 static DEFINE_SPINLOCK(slow_subchannel_lock);
 342
 343 static void
 344 css_trigger_slow_path(struct work_struct *unused)
 345 {
 346         CIO_TRACE_EVENT(4, "slowpath");
 347
 348         if (need_rescan) {
 349                 need_rescan = 0;
 350                 for_each_subchannel(css_rescan_devices, NULL);
 351                 return;
 352         }
 353
 354         spin_lock_irq(&slow_subchannel_lock);
 355         while (!list_empty(&slow_subchannels_head)) {
 356                 struct slow_subchannel *slow_sch =
 357                         list_entry(slow_subchannels_head.next,
 358                                    struct slow_subchannel, slow_list);
 359
 360                 list_del_init(slow_subchannels_head.next);
 361                 spin_unlock_irq(&slow_subchannel_lock);
 362                 css_evaluate_subchannel(slow_sch->schid, 1);
 363                 spin_lock_irq(&slow_subchannel_lock);
 364                 kfree(slow_sch);
 365         }
 366         spin_unlock_irq(&slow_subchannel_lock);
 367 }
 368
 369 DECLARE_WORK(slow_path_work, css_trigger_slow_path);
 370 struct workqueue_struct *slow_path_wq;
 371
 372 /* Reprobe subchannel if unregistered. */
 373 static int reprobe_subchannel(struct subchannel_id schid, void *data)
 374 {
 375         struct subchannel *sch;
 376         int ret;
 377
 378         CIO_DEBUG(KERN_INFO, 6, "cio: reprobe 0.%x.%04x\n",
 379                   schid.ssid, schid.sch_no);
 380         if (need_reprobe)
 381                 return -EAGAIN;
 382
 383         sch = get_subchannel_by_schid(schid);
 384         if (sch) {
 385                 /* Already known. */
 386                 put_device(&sch->dev);
 387                 return 0;
 388         }
 389
 390         ret = css_probe_device(schid);
 391         switch (ret) {
 392         case 0:
 393                 break;
 394         case -ENXIO:
 395         case -ENOMEM:
 396                 /* These should abort looping */
 397                 break;
 398         default:
 399                 ret = 0;
 400         }
 401
 402         return ret;
 403 }
 404
 405 /* Work function used to reprobe all unregistered subchannels. */
 406 static void reprobe_all(struct work_struct *unused)
 407 {
 408         int ret;
 409
 410         CIO_MSG_EVENT(2, "reprobe start\n");
 411
 412         need_reprobe = 0;
 413         /* Make sure initial subchannel scan is done. */
 414         wait_event(ccw_device_init_wq,
 415                    atomic_read(&ccw_device_init_count) == 0);
 416         ret = for_each_subchannel(reprobe_subchannel, NULL);
 417
 418         CIO_MSG_EVENT(2, "reprobe done (rc=%d, need_reprobe=%d)\n", ret,
 419                       need_reprobe);
 420 }
 421
 422 DECLARE_WORK(css_reprobe_work, reprobe_all);
 423
 424 /* Schedule reprobing of all unregistered subchannels. */
 425 void css_schedule_reprobe(void)
 426 {
 427         need_reprobe = 1;
 428         queue_work(ccw_device_work, &css_reprobe_work);
 429 }
 430
 431 EXPORT_SYMBOL_GPL(css_schedule_reprobe);
 432
 433 /*
 434  * Rescan for new devices. FIXME: This is slow.
 435  * This function is called when we have lost CRWs due to overflows and we have
 436  * to do subchannel housekeeping.
 437  */
 438 void
 439 css_reiterate_subchannels(void)
 440 {
 441         css_clear_subchannel_slow_list();
 442         need_rescan = 1;
 443 }
 444
 445 /*
 446  * Called from the machine check handler for subchannel report words.
 447  */
 448 int
 449 css_process_crw(int rsid1, int rsid2)
 450 {
 451         int ret;
 452         struct subchannel_id mchk_schid;
 453
 454         CIO_CRW_EVENT(2, "source is subchannel %04X, subsystem id %x\n",
 455                       rsid1, rsid2);
 456
 457         if (need_rescan)
 458                 /* We need to iterate all subchannels anyway. */
 459                 return -EAGAIN;
 460
 461         init_subchannel_id(&mchk_schid);
 462         mchk_schid.sch_no = rsid1;
 463         if (rsid2 != 0)
 464                 mchk_schid.ssid = (rsid2 >> 8) & 3;
 465
 466         /*
 467          * Since we are always presented with IPI in the CRW, we have to
 468          * use stsch() to find out if the subchannel in question has come
 469          * or gone.
 470          */
 471         ret = css_evaluate_subchannel(mchk_schid, 0);
 472         if (ret == -EAGAIN) {
 473                 if (css_enqueue_subchannel_slow(mchk_schid)) {
 474                         css_clear_subchannel_slow_list();
 475                         need_rescan = 1;
 476                 }
 477         }
 478         return ret;
 479 }
 480
 481 static int __init
 482 __init_channel_subsystem(struct subchannel_id schid, void *data)
 483 {
 484         struct subchannel *sch;
 485         int ret;
 486
 487         if (cio_is_console(schid))
 488                 sch = cio_get_console_subchannel();
 489         else {
 490                 sch = css_alloc_subchannel(schid);
 491                 if (IS_ERR(sch))
 492                         ret = PTR_ERR(sch);
 493                 else
 494                         ret = 0;
 495                 switch (ret) {
 496                 case 0:
 497                         break;
 498                 case -ENOMEM:
 499                         panic("Out of memory in init_channel_subsystem\n");
 500                 /* -ENXIO: no more subchannels. */
 501                 case -ENXIO:
 502                         return ret;
 503                 /* -EIO: this subchannel set not supported. */
 504                 case -EIO:
 505                         return ret;
 506                 default:
 507                         return 0;
 508                 }
 509         }
 510         /*
 511          * We register ALL valid subchannels in ioinfo, even those
 512          * that have been present before init_channel_subsystem.
 513          * These subchannels can't have been registered yet (kmalloc
 514          * not working) so we do it now. This is true e.g. for the
 515          * console subchannel.
 516          */
 517         css_register_subchannel(sch);
 518         return 0;
 519 }
 520
 521 static void __init
 522 css_generate_pgid(struct channel_subsystem *css, u32 tod_high)
 523 {
 524         if (css_characteristics_avail && css_general_characteristics.mcss) {
 525                 css->global_pgid.pgid_high.ext_cssid.version = 0x80;
 526                 css->global_pgid.pgid_high.ext_cssid.cssid = css->cssid;
 527         } else {
 528 #ifdef CONFIG_SMP
 529                 css->global_pgid.pgid_high.cpu_addr = hard_smp_processor_id();
 530 #else
 531                 css->global_pgid.pgid_high.cpu_addr = 0;
 532 #endif
 533         }
 534         css->global_pgid.cpu_id = ((cpuid_t *) __LC_CPUID)->ident;
 535         css->global_pgid.cpu_model = ((cpuid_t *) __LC_CPUID)->machine;
 536         css->global_pgid.tod_high = tod_high;
 537
 538 }
 539
 540 static void
 541 channel_subsystem_release(struct device *dev)
 542 {
 543         struct channel_subsystem *css;
 544
 545         css = to_css(dev);
 546         mutex_destroy(&css->mutex);
 547         kfree(css);
 548 }
 549
 550 static ssize_t
 551 css_cm_enable_show(struct device *dev, struct device_attribute *attr,
 552                    char *buf)
 553 {
 554         struct channel_subsystem *css = to_css(dev);
 555
 556         if (!css)
 557                 return 0;
 558         return sprintf(buf, "%x\n", css->cm_enabled);
 559 }
 560
 561 static ssize_t
 562 css_cm_enable_store(struct device *dev, struct device_attribute *attr,
 563                     const char *buf, size_t count)
 564 {
 565         struct channel_subsystem *css = to_css(dev);
 566         int ret;
 567
 568         switch (buf[0]) {
 569         case '0':
 570                 ret = css->cm_enabled ? chsc_secm(css, 0) : 0;
 571                 break;
 572         case '1':
 573                 ret = css->cm_enabled ? 0 : chsc_secm(css, 1);
 574                 break;
 575         default:
 576                 ret = -EINVAL;
 577         }
 578         return ret < 0 ? ret : count;
 579 }
 580
 581 static DEVICE_ATTR(cm_enable, 0644, css_cm_enable_show, css_cm_enable_store);
 582
 583 static inline void __init
 584 setup_css(int nr)
 585 {
 586         u32 tod_high;
 587
 588         memset(css[nr], 0, sizeof(struct channel_subsystem));
 589         mutex_init(&css[nr]->mutex);
 590         css[nr]->valid = 1;
 591         css[nr]->cssid = nr;
 592         sprintf(css[nr]->device.bus_id, "css%x", nr);
 593         css[nr]->device.release = channel_subsystem_release;
 594         tod_high = (u32) (get_clock() >> 32);
 595         css_generate_pgid(css[nr], tod_high);
 596 }
 597
 598 /*
 599  * Now that the driver core is running, we can setup our channel subsystem.
 600  * The struct subchannel's are created during probing (except for the
 601  * static console subchannel).
 602  */
 603 static int __init
 604 init_channel_subsystem (void)
 605 {
 606         int ret, i;
 607
 608         if (chsc_determine_css_characteristics() == 0)
 609                 css_characteristics_avail = 1;
 610
 611         if ((ret = bus_register(&css_bus_type)))
 612                 goto out;
 613
 614         /* Try to enable MSS. */
 615         ret = chsc_enable_facility(CHSC_SDA_OC_MSS);
 616         switch (ret) {
 617         case 0: /* Success. */
 618                 max_ssid = __MAX_SSID;
 619                 break;
 620         case -ENOMEM:
 621                 goto out_bus;
 622         default:
 623                 max_ssid = 0;
 624         }
 625         /* Setup css structure. */
 626         for (i = 0; i <= __MAX_CSSID; i++) {
 627                 css[i] = kmalloc(sizeof(struct channel_subsystem), GFP_KERNEL);
 628                 if (!css[i]) {
 629                         ret = -ENOMEM;
 630                         goto out_unregister;
 631                 }
 632                 setup_css(i);
 633                 ret = device_register(&css[i]->device);
 634                 if (ret)
 635                         goto out_free;
 636                 if (css_characteristics_avail &&
 637                     css_chsc_characteristics.secm) {
 638                         ret = device_create_file(&css[i]->device,
 639                                                  &dev_attr_cm_enable);
 640                         if (ret)
 641                                 goto out_device;
 642                 }
 643         }
 644         css_init_done = 1;
 645
 646         ctl_set_bit(6, 28);
 647
 648         for_each_subchannel(__init_channel_subsystem, NULL);
 649         return 0;
 650 out_device:
 651         device_unregister(&css[i]->device);
 652 out_free:
 653         kfree(css[i]);
 654 out_unregister:
 655         while (i > 0) {
 656                 i--;
 657                 if (css_characteristics_avail && css_chsc_characteristics.secm)
 658                         device_remove_file(&css[i]->device,
 659                                            &dev_attr_cm_enable);
 660                 device_unregister(&css[i]->device);
 661         }
 662 out_bus:
 663         bus_unregister(&css_bus_type);
 664 out:
 665         return ret;
 666 }
 667
 668 /*
 669  * find a driver for a subchannel. They identify by the subchannel
 670  * type with the exception that the console subchannel driver has its own
 671  * subchannel type although the device is an i/o subchannel
 672  */
 673 static int
 674 css_bus_match (struct device *dev, struct device_driver *drv)
 675 {
 676         struct subchannel *sch = container_of (dev, struct subchannel, dev);
 677         struct css_driver *driver = container_of (drv, struct css_driver, drv);
 678
 679         if (sch->st == driver->subchannel_type)
 680                 return 1;
 681
 682         return 0;
 683 }
 684
 685 static int
 686 css_probe (struct device *dev)
 687 {
 688         struct subchannel *sch;
 689
 690         sch = to_subchannel(dev);
 691         sch->driver = container_of (dev->driver, struct css_driver, drv);
 692         return (sch->driver->probe ? sch->driver->probe(sch) : 0);
 693 }
 694
 695 static int
 696 css_remove (struct device *dev)
 697 {
 698         struct subchannel *sch;
 699
 700         sch = to_subchannel(dev);
 701         return (sch->driver->remove ? sch->driver->remove(sch) : 0);
 702 }
 703
 704 static void
 705 css_shutdown (struct device *dev)
 706 {
 707         struct subchannel *sch;
 708
 709         sch = to_subchannel(dev);
 710         if (sch->driver->shutdown)
 711                 sch->driver->shutdown(sch);
 712 }
 713
 714 struct bus_type css_bus_type = {
 715         .name     = "css",
 716         .match    = css_bus_match,
 717         .probe    = css_probe,
 718         .remove   = css_remove,
 719         .shutdown = css_shutdown,
 720 };
 721
 722 subsys_initcall(init_channel_subsystem);
 723
 724 int
 725 css_enqueue_subchannel_slow(struct subchannel_id schid)
 726 {
 727         struct slow_subchannel *new_slow_sch;
 728         unsigned long flags;
 729
 730         new_slow_sch = kzalloc(sizeof(struct slow_subchannel), GFP_ATOMIC);
 731         if (!new_slow_sch)
 732                 return -ENOMEM;
 733         new_slow_sch->schid = schid;
 734         spin_lock_irqsave(&slow_subchannel_lock, flags);
 735         list_add_tail(&new_slow_sch->slow_list, &slow_subchannels_head);
 736         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 737         return 0;
 738 }
 739
 740 void
 741 css_clear_subchannel_slow_list(void)
 742 {
 743         unsigned long flags;
 744
 745         spin_lock_irqsave(&slow_subchannel_lock, flags);
 746         while (!list_empty(&slow_subchannels_head)) {
 747                 struct slow_subchannel *slow_sch =
 748                         list_entry(slow_subchannels_head.next,
 749                                    struct slow_subchannel, slow_list);
 750
 751                 list_del_init(slow_subchannels_head.next);
 752                 kfree(slow_sch);
 753         }
 754         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 755 }
 756
 757
 758
 759 int
 760 css_slow_subchannels_exist(void)
 761 {
 762         return (!list_empty(&slow_subchannels_head));
 763 }
 764
 765 MODULE_LICENSE("GPL");
 766 EXPORT_SYMBOL(css_bus_type);
 767 EXPORT_SYMBOL_GPL(css_characteristics_avail);