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->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         sch->dev.groups = subch_attr_groups;
 141
 142         /* make it known to the system */
 143         ret = css_sch_device_register(sch);
 144         if (ret) {
 145                 printk (KERN_WARNING "%s: could not register %s\n",
 146                         __func__, sch->dev.bus_id);
 147                 return ret;
 148         }
 149         css_get_ssd_info(sch);
 150         return ret;
 151 }
 152
 153 int
 154 css_probe_device(struct subchannel_id schid)
 155 {
 156         int ret;
 157         struct subchannel *sch;
 158
 159         sch = css_alloc_subchannel(schid);
 160         if (IS_ERR(sch))
 161                 return PTR_ERR(sch);
 162         ret = css_register_subchannel(sch);
 163         if (ret)
 164                 css_free_subchannel(sch);
 165         return ret;
 166 }
 167
 168 static int
 169 check_subchannel(struct device * dev, void * data)
 170 {
 171         struct subchannel *sch;
 172         struct subchannel_id *schid = data;
 173
 174         sch = to_subchannel(dev);
 175         return schid_equal(&sch->schid, schid);
 176 }
 177
 178 struct subchannel *
 179 get_subchannel_by_schid(struct subchannel_id schid)
 180 {
 181         struct device *dev;
 182
 183         dev = bus_find_device(&css_bus_type, NULL,
 184                               &schid, check_subchannel);
 185
 186         return dev ? to_subchannel(dev) : NULL;
 187 }
 188
 189 static inline int css_get_subchannel_status(struct subchannel *sch)
 190 {
 191         struct schib schib;
 192
 193         if (stsch(sch->schid, &schib) || !schib.pmcw.dnv)
 194                 return CIO_GONE;
 195         if (sch->schib.pmcw.dnv && (schib.pmcw.dev != sch->schib.pmcw.dev))
 196                 return CIO_REVALIDATE;
 197         if (!sch->lpm)
 198                 return CIO_NO_PATH;
 199         return CIO_OPER;
 200 }
 201
 202 static int css_evaluate_known_subchannel(struct subchannel *sch, int slow)
 203 {
 204         int event, ret, disc;
 205         unsigned long flags;
 206         enum { NONE, UNREGISTER, UNREGISTER_PROBE, REPROBE } action;
 207
 208         spin_lock_irqsave(sch->lock, flags);
 209         disc = device_is_disconnected(sch);
 210         if (disc && slow) {
 211                 /* Disconnected devices are evaluated directly only.*/
 212                 spin_unlock_irqrestore(sch->lock, flags);
 213                 return 0;
 214         }
 215         /* No interrupt after machine check - kill pending timers. */
 216         device_kill_pending_timer(sch);
 217         if (!disc && !slow) {
 218                 /* Non-disconnected devices are evaluated on the slow path. */
 219                 spin_unlock_irqrestore(sch->lock, flags);
 220                 return -EAGAIN;
 221         }
 222         event = css_get_subchannel_status(sch);
 223         CIO_MSG_EVENT(4, "Evaluating schid 0.%x.%04x, event %d, %s, %s path.\n",
 224                       sch->schid.ssid, sch->schid.sch_no, event,
 225                       disc ? "disconnected" : "normal",
 226                       slow ? "slow" : "fast");
 227         /* Analyze subchannel status. */
 228         action = NONE;
 229         switch (event) {
 230         case CIO_NO_PATH:
 231                 if (disc) {
 232                         /* Check if paths have become available. */
 233                         action = REPROBE;
 234                         break;
 235                 }
 236                 /* fall through */
 237         case CIO_GONE:
 238                 /* Prevent unwanted effects when opening lock. */
 239                 cio_disable_subchannel(sch);
 240                 device_set_disconnected(sch);
 241                 /* Ask driver what to do with device. */
 242                 action = UNREGISTER;
 243                 if (sch->driver && sch->driver->notify) {
 244                         spin_unlock_irqrestore(sch->lock, flags);
 245                         ret = sch->driver->notify(&sch->dev, event);
 246                         spin_lock_irqsave(sch->lock, flags);
 247                         if (ret)
 248                                 action = NONE;
 249                 }
 250                 break;
 251         case CIO_REVALIDATE:
 252                 /* Device will be removed, so no notify necessary. */
 253                 if (disc)
 254                         /* Reprobe because immediate unregister might block. */
 255                         action = REPROBE;
 256                 else
 257                         action = UNREGISTER_PROBE;
 258                 break;
 259         case CIO_OPER:
 260                 if (disc)
 261                         /* Get device operational again. */
 262                         action = REPROBE;
 263                 break;
 264         }
 265         /* Perform action. */
 266         ret = 0;
 267         switch (action) {
 268         case UNREGISTER:
 269         case UNREGISTER_PROBE:
 270                 /* Unregister device (will use subchannel lock). */
 271                 spin_unlock_irqrestore(sch->lock, flags);
 272                 css_sch_device_unregister(sch);
 273                 spin_lock_irqsave(sch->lock, flags);
 274
 275                 /* Reset intparm to zeroes. */
 276                 sch->schib.pmcw.intparm = 0;
 277                 cio_modify(sch);
 278                 break;
 279         case REPROBE:
 280                 device_trigger_reprobe(sch);
 281                 break;
 282         default:
 283                 break;
 284         }
 285         spin_unlock_irqrestore(sch->lock, flags);
 286         /* Probe if necessary. */
 287         if (action == UNREGISTER_PROBE)
 288                 ret = css_probe_device(sch->schid);
 289
 290         return ret;
 291 }
 292
 293 static int css_evaluate_new_subchannel(struct subchannel_id schid, int slow)
 294 {
 295         struct schib schib;
 296
 297         if (!slow) {
 298                 /* Will be done on the slow path. */
 299                 return -EAGAIN;
 300         }
 301         if (stsch(schid, &schib) || !schib.pmcw.dnv) {
 302                 /* Unusable - ignore. */
 303                 return 0;
 304         }
 305         CIO_MSG_EVENT(4, "Evaluating schid 0.%x.%04x, event %d, unknown, "
 306                          "slow path.\n", schid.ssid, schid.sch_no, CIO_OPER);
 307
 308         return css_probe_device(schid);
 309 }
 310
 311 static int css_evaluate_subchannel(struct subchannel_id schid, int slow)
 312 {
 313         struct subchannel *sch;
 314         int ret;
 315
 316         sch = get_subchannel_by_schid(schid);
 317         if (sch) {
 318                 ret = css_evaluate_known_subchannel(sch, slow);
 319                 put_device(&sch->dev);
 320         } else
 321                 ret = css_evaluate_new_subchannel(schid, slow);
 322
 323         return ret;
 324 }
 325
 326 static int
 327 css_rescan_devices(struct subchannel_id schid, void *data)
 328 {
 329         return css_evaluate_subchannel(schid, 1);
 330 }
 331
 332 struct slow_subchannel {
 333         struct list_head slow_list;
 334         struct subchannel_id schid;
 335 };
 336
 337 static LIST_HEAD(slow_subchannels_head);
 338 static DEFINE_SPINLOCK(slow_subchannel_lock);
 339
 340 static void
 341 css_trigger_slow_path(struct work_struct *unused)
 342 {
 343         CIO_TRACE_EVENT(4, "slowpath");
 344
 345         if (need_rescan) {
 346                 need_rescan = 0;
 347                 for_each_subchannel(css_rescan_devices, NULL);
 348                 return;
 349         }
 350
 351         spin_lock_irq(&slow_subchannel_lock);
 352         while (!list_empty(&slow_subchannels_head)) {
 353                 struct slow_subchannel *slow_sch =
 354                         list_entry(slow_subchannels_head.next,
 355                                    struct slow_subchannel, slow_list);
 356
 357                 list_del_init(slow_subchannels_head.next);
 358                 spin_unlock_irq(&slow_subchannel_lock);
 359                 css_evaluate_subchannel(slow_sch->schid, 1);
 360                 spin_lock_irq(&slow_subchannel_lock);
 361                 kfree(slow_sch);
 362         }
 363         spin_unlock_irq(&slow_subchannel_lock);
 364 }
 365
 366 DECLARE_WORK(slow_path_work, css_trigger_slow_path);
 367 struct workqueue_struct *slow_path_wq;
 368
 369 /* Reprobe subchannel if unregistered. */
 370 static int reprobe_subchannel(struct subchannel_id schid, void *data)
 371 {
 372         struct subchannel *sch;
 373         int ret;
 374
 375         CIO_DEBUG(KERN_INFO, 6, "cio: reprobe 0.%x.%04x\n",
 376                   schid.ssid, schid.sch_no);
 377         if (need_reprobe)
 378                 return -EAGAIN;
 379
 380         sch = get_subchannel_by_schid(schid);
 381         if (sch) {
 382                 /* Already known. */
 383                 put_device(&sch->dev);
 384                 return 0;
 385         }
 386
 387         ret = css_probe_device(schid);
 388         switch (ret) {
 389         case 0:
 390                 break;
 391         case -ENXIO:
 392         case -ENOMEM:
 393                 /* These should abort looping */
 394                 break;
 395         default:
 396                 ret = 0;
 397         }
 398
 399         return ret;
 400 }
 401
 402 /* Work function used to reprobe all unregistered subchannels. */
 403 static void reprobe_all(struct work_struct *unused)
 404 {
 405         int ret;
 406
 407         CIO_MSG_EVENT(2, "reprobe start\n");
 408
 409         need_reprobe = 0;
 410         /* Make sure initial subchannel scan is done. */
 411         wait_event(ccw_device_init_wq,
 412                    atomic_read(&ccw_device_init_count) == 0);
 413         ret = for_each_subchannel(reprobe_subchannel, NULL);
 414
 415         CIO_MSG_EVENT(2, "reprobe done (rc=%d, need_reprobe=%d)\n", ret,
 416                       need_reprobe);
 417 }
 418
 419 DECLARE_WORK(css_reprobe_work, reprobe_all);
 420
 421 /* Schedule reprobing of all unregistered subchannels. */
 422 void css_schedule_reprobe(void)
 423 {
 424         need_reprobe = 1;
 425         queue_work(ccw_device_work, &css_reprobe_work);
 426 }
 427
 428 EXPORT_SYMBOL_GPL(css_schedule_reprobe);
 429
 430 /*
 431  * Rescan for new devices. FIXME: This is slow.
 432  * This function is called when we have lost CRWs due to overflows and we have
 433  * to do subchannel housekeeping.
 434  */
 435 void
 436 css_reiterate_subchannels(void)
 437 {
 438         css_clear_subchannel_slow_list();
 439         need_rescan = 1;
 440 }
 441
 442 /*
 443  * Called from the machine check handler for subchannel report words.
 444  */
 445 int
 446 css_process_crw(int rsid1, int rsid2)
 447 {
 448         int ret;
 449         struct subchannel_id mchk_schid;
 450
 451         CIO_CRW_EVENT(2, "source is subchannel %04X, subsystem id %x\n",
 452                       rsid1, rsid2);
 453
 454         if (need_rescan)
 455                 /* We need to iterate all subchannels anyway. */
 456                 return -EAGAIN;
 457
 458         init_subchannel_id(&mchk_schid);
 459         mchk_schid.sch_no = rsid1;
 460         if (rsid2 != 0)
 461                 mchk_schid.ssid = (rsid2 >> 8) & 3;
 462
 463         /*
 464          * Since we are always presented with IPI in the CRW, we have to
 465          * use stsch() to find out if the subchannel in question has come
 466          * or gone.
 467          */
 468         ret = css_evaluate_subchannel(mchk_schid, 0);
 469         if (ret == -EAGAIN) {
 470                 if (css_enqueue_subchannel_slow(mchk_schid)) {
 471                         css_clear_subchannel_slow_list();
 472                         need_rescan = 1;
 473                 }
 474         }
 475         return ret;
 476 }
 477
 478 static int __init
 479 __init_channel_subsystem(struct subchannel_id schid, void *data)
 480 {
 481         struct subchannel *sch;
 482         int ret;
 483
 484         if (cio_is_console(schid))
 485                 sch = cio_get_console_subchannel();
 486         else {
 487                 sch = css_alloc_subchannel(schid);
 488                 if (IS_ERR(sch))
 489                         ret = PTR_ERR(sch);
 490                 else
 491                         ret = 0;
 492                 switch (ret) {
 493                 case 0:
 494                         break;
 495                 case -ENOMEM:
 496                         panic("Out of memory in init_channel_subsystem\n");
 497                 /* -ENXIO: no more subchannels. */
 498                 case -ENXIO:
 499                         return ret;
 500                 /* -EIO: this subchannel set not supported. */
 501                 case -EIO:
 502                         return ret;
 503                 default:
 504                         return 0;
 505                 }
 506         }
 507         /*
 508          * We register ALL valid subchannels in ioinfo, even those
 509          * that have been present before init_channel_subsystem.
 510          * These subchannels can't have been registered yet (kmalloc
 511          * not working) so we do it now. This is true e.g. for the
 512          * console subchannel.
 513          */
 514         css_register_subchannel(sch);
 515         return 0;
 516 }
 517
 518 static void __init
 519 css_generate_pgid(struct channel_subsystem *css, u32 tod_high)
 520 {
 521         if (css_characteristics_avail && css_general_characteristics.mcss) {
 522                 css->global_pgid.pgid_high.ext_cssid.version = 0x80;
 523                 css->global_pgid.pgid_high.ext_cssid.cssid = css->cssid;
 524         } else {
 525 #ifdef CONFIG_SMP
 526                 css->global_pgid.pgid_high.cpu_addr = hard_smp_processor_id();
 527 #else
 528                 css->global_pgid.pgid_high.cpu_addr = 0;
 529 #endif
 530         }
 531         css->global_pgid.cpu_id = ((cpuid_t *) __LC_CPUID)->ident;
 532         css->global_pgid.cpu_model = ((cpuid_t *) __LC_CPUID)->machine;
 533         css->global_pgid.tod_high = tod_high;
 534
 535 }
 536
 537 static void
 538 channel_subsystem_release(struct device *dev)
 539 {
 540         struct channel_subsystem *css;
 541
 542         css = to_css(dev);
 543         mutex_destroy(&css->mutex);
 544         kfree(css);
 545 }
 546
 547 static ssize_t
 548 css_cm_enable_show(struct device *dev, struct device_attribute *attr,
 549                    char *buf)
 550 {
 551         struct channel_subsystem *css = to_css(dev);
 552
 553         if (!css)
 554                 return 0;
 555         return sprintf(buf, "%x\n", css->cm_enabled);
 556 }
 557
 558 static ssize_t
 559 css_cm_enable_store(struct device *dev, struct device_attribute *attr,
 560                     const char *buf, size_t count)
 561 {
 562         struct channel_subsystem *css = to_css(dev);
 563         int ret;
 564
 565         switch (buf[0]) {
 566         case '0':
 567                 ret = css->cm_enabled ? chsc_secm(css, 0) : 0;
 568                 break;
 569         case '1':
 570                 ret = css->cm_enabled ? 0 : chsc_secm(css, 1);
 571                 break;
 572         default:
 573                 ret = -EINVAL;
 574         }
 575         return ret < 0 ? ret : count;
 576 }
 577
 578 static DEVICE_ATTR(cm_enable, 0644, css_cm_enable_show, css_cm_enable_store);
 579
 580 static inline int __init setup_css(int nr)
 581 {
 582         u32 tod_high;
 583         int ret;
 584
 585         memset(css[nr], 0, sizeof(struct channel_subsystem));
 586         css[nr]->pseudo_subchannel =
 587                 kzalloc(sizeof(*css[nr]->pseudo_subchannel), GFP_KERNEL);
 588         if (!css[nr]->pseudo_subchannel)
 589                 return -ENOMEM;
 590         css[nr]->pseudo_subchannel->dev.parent = &css[nr]->device;
 591         css[nr]->pseudo_subchannel->dev.release = css_subchannel_release;
 592         sprintf(css[nr]->pseudo_subchannel->dev.bus_id, "defunct");
 593         ret = cio_create_sch_lock(css[nr]->pseudo_subchannel);
 594         if (ret) {
 595                 kfree(css[nr]->pseudo_subchannel);
 596                 return ret;
 597         }
 598         mutex_init(&css[nr]->mutex);
 599         css[nr]->valid = 1;
 600         css[nr]->cssid = nr;
 601         sprintf(css[nr]->device.bus_id, "css%x", nr);
 602         css[nr]->device.release = channel_subsystem_release;
 603         tod_high = (u32) (get_clock() >> 32);
 604         css_generate_pgid(css[nr], tod_high);
 605         return 0;
 606 }
 607
 608 /*
 609  * Now that the driver core is running, we can setup our channel subsystem.
 610  * The struct subchannel's are created during probing (except for the
 611  * static console subchannel).
 612  */
 613 static int __init
 614 init_channel_subsystem (void)
 615 {
 616         int ret, i;
 617
 618         if (chsc_determine_css_characteristics() == 0)
 619                 css_characteristics_avail = 1;
 620
 621         if ((ret = bus_register(&css_bus_type)))
 622                 goto out;
 623
 624         /* Try to enable MSS. */
 625         ret = chsc_enable_facility(CHSC_SDA_OC_MSS);
 626         switch (ret) {
 627         case 0: /* Success. */
 628                 max_ssid = __MAX_SSID;
 629                 break;
 630         case -ENOMEM:
 631                 goto out_bus;
 632         default:
 633                 max_ssid = 0;
 634         }
 635         /* Setup css structure. */
 636         for (i = 0; i <= __MAX_CSSID; i++) {
 637                 css[i] = kmalloc(sizeof(struct channel_subsystem), GFP_KERNEL);
 638                 if (!css[i]) {
 639                         ret = -ENOMEM;
 640                         goto out_unregister;
 641                 }
 642                 ret = setup_css(i);
 643                 if (ret)
 644                         goto out_free;
 645                 ret = device_register(&css[i]->device);
 646                 if (ret)
 647                         goto out_free_all;
 648                 if (css_characteristics_avail &&
 649                     css_chsc_characteristics.secm) {
 650                         ret = device_create_file(&css[i]->device,
 651                                                  &dev_attr_cm_enable);
 652                         if (ret)
 653                                 goto out_device;
 654                 }
 655                 ret = device_register(&css[i]->pseudo_subchannel->dev);
 656                 if (ret)
 657                         goto out_file;
 658         }
 659         css_init_done = 1;
 660
 661         ctl_set_bit(6, 28);
 662
 663         for_each_subchannel(__init_channel_subsystem, NULL);
 664         return 0;
 665 out_file:
 666         device_remove_file(&css[i]->device, &dev_attr_cm_enable);
 667 out_device:
 668         device_unregister(&css[i]->device);
 669 out_free_all:
 670         kfree(css[i]->pseudo_subchannel->lock);
 671         kfree(css[i]->pseudo_subchannel);
 672 out_free:
 673         kfree(css[i]);
 674 out_unregister:
 675         while (i > 0) {
 676                 i--;
 677                 device_unregister(&css[i]->pseudo_subchannel->dev);
 678                 if (css_characteristics_avail && css_chsc_characteristics.secm)
 679                         device_remove_file(&css[i]->device,
 680                                            &dev_attr_cm_enable);
 681                 device_unregister(&css[i]->device);
 682         }
 683 out_bus:
 684         bus_unregister(&css_bus_type);
 685 out:
 686         return ret;
 687 }
 688
 689 int sch_is_pseudo_sch(struct subchannel *sch)
 690 {
 691         return sch == to_css(sch->dev.parent)->pseudo_subchannel;
 692 }
 693
 694 /*
 695  * find a driver for a subchannel. They identify by the subchannel
 696  * type with the exception that the console subchannel driver has its own
 697  * subchannel type although the device is an i/o subchannel
 698  */
 699 static int
 700 css_bus_match (struct device *dev, struct device_driver *drv)
 701 {
 702         struct subchannel *sch = container_of (dev, struct subchannel, dev);
 703         struct css_driver *driver = container_of (drv, struct css_driver, drv);
 704
 705         if (sch->st == driver->subchannel_type)
 706                 return 1;
 707
 708         return 0;
 709 }
 710
 711 static int
 712 css_probe (struct device *dev)
 713 {
 714         struct subchannel *sch;
 715
 716         sch = to_subchannel(dev);
 717         sch->driver = container_of (dev->driver, struct css_driver, drv);
 718         return (sch->driver->probe ? sch->driver->probe(sch) : 0);
 719 }
 720
 721 static int
 722 css_remove (struct device *dev)
 723 {
 724         struct subchannel *sch;
 725
 726         sch = to_subchannel(dev);
 727         return (sch->driver->remove ? sch->driver->remove(sch) : 0);
 728 }
 729
 730 static void
 731 css_shutdown (struct device *dev)
 732 {
 733         struct subchannel *sch;
 734
 735         sch = to_subchannel(dev);
 736         if (sch->driver->shutdown)
 737                 sch->driver->shutdown(sch);
 738 }
 739
 740 struct bus_type css_bus_type = {
 741         .name     = "css",
 742         .match    = css_bus_match,
 743         .probe    = css_probe,
 744         .remove   = css_remove,
 745         .shutdown = css_shutdown,
 746 };
 747
 748 subsys_initcall(init_channel_subsystem);
 749
 750 int
 751 css_enqueue_subchannel_slow(struct subchannel_id schid)
 752 {
 753         struct slow_subchannel *new_slow_sch;
 754         unsigned long flags;
 755
 756         new_slow_sch = kzalloc(sizeof(struct slow_subchannel), GFP_ATOMIC);
 757         if (!new_slow_sch)
 758                 return -ENOMEM;
 759         new_slow_sch->schid = schid;
 760         spin_lock_irqsave(&slow_subchannel_lock, flags);
 761         list_add_tail(&new_slow_sch->slow_list, &slow_subchannels_head);
 762         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 763         return 0;
 764 }
 765
 766 void
 767 css_clear_subchannel_slow_list(void)
 768 {
 769         unsigned long flags;
 770
 771         spin_lock_irqsave(&slow_subchannel_lock, flags);
 772         while (!list_empty(&slow_subchannels_head)) {
 773                 struct slow_subchannel *slow_sch =
 774                         list_entry(slow_subchannels_head.next,
 775                                    struct slow_subchannel, slow_list);
 776
 777                 list_del_init(slow_subchannels_head.next);
 778                 kfree(slow_sch);
 779         }
 780         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 781 }
 782
 783
 784
 785 int
 786 css_slow_subchannels_exist(void)
 787 {
 788         return (!list_empty(&slow_subchannels_head));
 789 }
 790
 791 MODULE_LICENSE("GPL");
 792 EXPORT_SYMBOL(css_bus_type);
 793 EXPORT_SYMBOL_GPL(css_characteristics_avail);