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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 #include "idset.h"
  24
  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 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 int css_sch_device_register(struct subchannel *sch)
 112 {
 113         int ret;
 114
 115         mutex_lock(&sch->reg_mutex);
 116         ret = device_register(&sch->dev);
 117         mutex_unlock(&sch->reg_mutex);
 118         return ret;
 119 }
 120
 121 void css_sch_device_unregister(struct subchannel *sch)
 122 {
 123         mutex_lock(&sch->reg_mutex);
 124         device_unregister(&sch->dev);
 125         mutex_unlock(&sch->reg_mutex);
 126 }
 127
 128 static int
 129 css_register_subchannel(struct subchannel *sch)
 130 {
 131         int ret;
 132
 133         /* Initialize the subchannel structure */
 134         sch->dev.parent = &css[0]->device;
 135         sch->dev.bus = &css_bus_type;
 136         sch->dev.release = &css_subchannel_release;
 137         sch->dev.groups = subch_attr_groups;
 138
 139         css_get_ssd_info(sch);
 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         return ret;
 149 }
 150
 151 int
 152 css_probe_device(struct subchannel_id schid)
 153 {
 154         int ret;
 155         struct subchannel *sch;
 156
 157         sch = css_alloc_subchannel(schid);
 158         if (IS_ERR(sch))
 159                 return PTR_ERR(sch);
 160         ret = css_register_subchannel(sch);
 161         if (ret)
 162                 css_free_subchannel(sch);
 163         return ret;
 164 }
 165
 166 static int
 167 check_subchannel(struct device * dev, void * data)
 168 {
 169         struct subchannel *sch;
 170         struct subchannel_id *schid = data;
 171
 172         sch = to_subchannel(dev);
 173         return schid_equal(&sch->schid, schid);
 174 }
 175
 176 struct subchannel *
 177 get_subchannel_by_schid(struct subchannel_id schid)
 178 {
 179         struct device *dev;
 180
 181         dev = bus_find_device(&css_bus_type, NULL,
 182                               &schid, check_subchannel);
 183
 184         return dev ? to_subchannel(dev) : NULL;
 185 }
 186
 187 static int css_get_subchannel_status(struct subchannel *sch)
 188 {
 189         struct schib schib;
 190
 191         if (stsch(sch->schid, &schib) || !schib.pmcw.dnv)
 192                 return CIO_GONE;
 193         if (sch->schib.pmcw.dnv && (schib.pmcw.dev != sch->schib.pmcw.dev))
 194                 return CIO_REVALIDATE;
 195         if (!sch->lpm)
 196                 return CIO_NO_PATH;
 197         return CIO_OPER;
 198 }
 199
 200 static int css_evaluate_known_subchannel(struct subchannel *sch, int slow)
 201 {
 202         int event, ret, disc;
 203         unsigned long flags;
 204         enum { NONE, UNREGISTER, UNREGISTER_PROBE, REPROBE } action;
 205
 206         spin_lock_irqsave(sch->lock, flags);
 207         disc = device_is_disconnected(sch);
 208         if (disc && slow) {
 209                 /* Disconnected devices are evaluated directly only.*/
 210                 spin_unlock_irqrestore(sch->lock, flags);
 211                 return 0;
 212         }
 213         /* No interrupt after machine check - kill pending timers. */
 214         device_kill_pending_timer(sch);
 215         if (!disc && !slow) {
 216                 /* Non-disconnected devices are evaluated on the slow path. */
 217                 spin_unlock_irqrestore(sch->lock, flags);
 218                 return -EAGAIN;
 219         }
 220         event = css_get_subchannel_status(sch);
 221         CIO_MSG_EVENT(4, "Evaluating schid 0.%x.%04x, event %d, %s, %s path.\n",
 222                       sch->schid.ssid, sch->schid.sch_no, event,
 223                       disc ? "disconnected" : "normal",
 224                       slow ? "slow" : "fast");
 225         /* Analyze subchannel status. */
 226         action = NONE;
 227         switch (event) {
 228         case CIO_NO_PATH:
 229                 if (disc) {
 230                         /* Check if paths have become available. */
 231                         action = REPROBE;
 232                         break;
 233                 }
 234                 /* fall through */
 235         case CIO_GONE:
 236                 /* Prevent unwanted effects when opening lock. */
 237                 cio_disable_subchannel(sch);
 238                 device_set_disconnected(sch);
 239                 /* Ask driver what to do with device. */
 240                 action = UNREGISTER;
 241                 if (sch->driver && sch->driver->notify) {
 242                         spin_unlock_irqrestore(sch->lock, flags);
 243                         ret = sch->driver->notify(&sch->dev, event);
 244                         spin_lock_irqsave(sch->lock, flags);
 245                         if (ret)
 246                                 action = NONE;
 247                 }
 248                 break;
 249         case CIO_REVALIDATE:
 250                 /* Device will be removed, so no notify necessary. */
 251                 if (disc)
 252                         /* Reprobe because immediate unregister might block. */
 253                         action = REPROBE;
 254                 else
 255                         action = UNREGISTER_PROBE;
 256                 break;
 257         case CIO_OPER:
 258                 if (disc)
 259                         /* Get device operational again. */
 260                         action = REPROBE;
 261                 break;
 262         }
 263         /* Perform action. */
 264         ret = 0;
 265         switch (action) {
 266         case UNREGISTER:
 267         case UNREGISTER_PROBE:
 268                 /* Unregister device (will use subchannel lock). */
 269                 spin_unlock_irqrestore(sch->lock, flags);
 270                 css_sch_device_unregister(sch);
 271                 spin_lock_irqsave(sch->lock, flags);
 272
 273                 /* Reset intparm to zeroes. */
 274                 sch->schib.pmcw.intparm = 0;
 275                 cio_modify(sch);
 276                 break;
 277         case REPROBE:
 278                 device_trigger_reprobe(sch);
 279                 break;
 280         default:
 281                 break;
 282         }
 283         spin_unlock_irqrestore(sch->lock, flags);
 284         /* Probe if necessary. */
 285         if (action == UNREGISTER_PROBE)
 286                 ret = css_probe_device(sch->schid);
 287
 288         return ret;
 289 }
 290
 291 static int css_evaluate_new_subchannel(struct subchannel_id schid, int slow)
 292 {
 293         struct schib schib;
 294
 295         if (!slow) {
 296                 /* Will be done on the slow path. */
 297                 return -EAGAIN;
 298         }
 299         if (stsch_err(schid, &schib) || !schib.pmcw.dnv) {
 300                 /* Unusable - ignore. */
 301                 return 0;
 302         }
 303         CIO_MSG_EVENT(4, "Evaluating schid 0.%x.%04x, event %d, unknown, "
 304                          "slow path.\n", schid.ssid, schid.sch_no, CIO_OPER);
 305
 306         return css_probe_device(schid);
 307 }
 308
 309 static void css_evaluate_subchannel(struct subchannel_id schid, int slow)
 310 {
 311         struct subchannel *sch;
 312         int ret;
 313
 314         sch = get_subchannel_by_schid(schid);
 315         if (sch) {
 316                 ret = css_evaluate_known_subchannel(sch, slow);
 317                 put_device(&sch->dev);
 318         } else
 319                 ret = css_evaluate_new_subchannel(schid, slow);
 320         if (ret == -EAGAIN)
 321                 css_schedule_eval(schid);
 322 }
 323
 324 static struct idset *slow_subchannel_set;
 325 static spinlock_t slow_subchannel_lock;
 326
 327 static int __init slow_subchannel_init(void)
 328 {
 329         spin_lock_init(&slow_subchannel_lock);
 330         slow_subchannel_set = idset_sch_new();
 331         if (!slow_subchannel_set) {
 332                 printk(KERN_WARNING "cio: could not allocate slow subchannel "
 333                        "set\n");
 334                 return -ENOMEM;
 335         }
 336         return 0;
 337 }
 338
 339 subsys_initcall(slow_subchannel_init);
 340
 341 static void css_slow_path_func(struct work_struct *unused)
 342 {
 343         struct subchannel_id schid;
 344
 345         CIO_TRACE_EVENT(4, "slowpath");
 346         spin_lock_irq(&slow_subchannel_lock);
 347         init_subchannel_id(&schid);
 348         while (idset_sch_get_first(slow_subchannel_set, &schid)) {
 349                 idset_sch_del(slow_subchannel_set, schid);
 350                 spin_unlock_irq(&slow_subchannel_lock);
 351                 css_evaluate_subchannel(schid, 1);
 352                 spin_lock_irq(&slow_subchannel_lock);
 353         }
 354         spin_unlock_irq(&slow_subchannel_lock);
 355 }
 356
 357 static DECLARE_WORK(slow_path_work, css_slow_path_func);
 358 struct workqueue_struct *slow_path_wq;
 359
 360 void css_schedule_eval(struct subchannel_id schid)
 361 {
 362         unsigned long flags;
 363
 364         spin_lock_irqsave(&slow_subchannel_lock, flags);
 365         idset_sch_add(slow_subchannel_set, schid);
 366         queue_work(slow_path_wq, &slow_path_work);
 367         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 368 }
 369
 370 void css_schedule_eval_all(void)
 371 {
 372         unsigned long flags;
 373
 374         spin_lock_irqsave(&slow_subchannel_lock, flags);
 375         idset_fill(slow_subchannel_set);
 376         queue_work(slow_path_wq, &slow_path_work);
 377         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 378 }
 379
 380 /* Reprobe subchannel if unregistered. */
 381 static int reprobe_subchannel(struct subchannel_id schid, void *data)
 382 {
 383         struct subchannel *sch;
 384         int ret;
 385
 386         CIO_DEBUG(KERN_INFO, 6, "cio: reprobe 0.%x.%04x\n",
 387                   schid.ssid, schid.sch_no);
 388         if (need_reprobe)
 389                 return -EAGAIN;
 390
 391         sch = get_subchannel_by_schid(schid);
 392         if (sch) {
 393                 /* Already known. */
 394                 put_device(&sch->dev);
 395                 return 0;
 396         }
 397
 398         ret = css_probe_device(schid);
 399         switch (ret) {
 400         case 0:
 401                 break;
 402         case -ENXIO:
 403         case -ENOMEM:
 404                 /* These should abort looping */
 405                 break;
 406         default:
 407                 ret = 0;
 408         }
 409
 410         return ret;
 411 }
 412
 413 /* Work function used to reprobe all unregistered subchannels. */
 414 static void reprobe_all(struct work_struct *unused)
 415 {
 416         int ret;
 417
 418         CIO_MSG_EVENT(2, "reprobe start\n");
 419
 420         need_reprobe = 0;
 421         /* Make sure initial subchannel scan is done. */
 422         wait_event(ccw_device_init_wq,
 423                    atomic_read(&ccw_device_init_count) == 0);
 424         ret = for_each_subchannel(reprobe_subchannel, NULL);
 425
 426         CIO_MSG_EVENT(2, "reprobe done (rc=%d, need_reprobe=%d)\n", ret,
 427                       need_reprobe);
 428 }
 429
 430 static DECLARE_WORK(css_reprobe_work, reprobe_all);
 431
 432 /* Schedule reprobing of all unregistered subchannels. */
 433 void css_schedule_reprobe(void)
 434 {
 435         need_reprobe = 1;
 436         queue_work(ccw_device_work, &css_reprobe_work);
 437 }
 438
 439 EXPORT_SYMBOL_GPL(css_schedule_reprobe);
 440
 441 /*
 442  * Called from the machine check handler for subchannel report words.
 443  */
 444 void css_process_crw(int rsid1, int rsid2)
 445 {
 446         struct subchannel_id mchk_schid;
 447
 448         CIO_CRW_EVENT(2, "source is subchannel %04X, subsystem id %x\n",
 449                       rsid1, rsid2);
 450         init_subchannel_id(&mchk_schid);
 451         mchk_schid.sch_no = rsid1;
 452         if (rsid2 != 0)
 453                 mchk_schid.ssid = (rsid2 >> 8) & 3;
 454
 455         /*
 456          * Since we are always presented with IPI in the CRW, we have to
 457          * use stsch() to find out if the subchannel in question has come
 458          * or gone.
 459          */
 460         css_evaluate_subchannel(mchk_schid, 0);
 461 }
 462
 463 static int __init
 464 __init_channel_subsystem(struct subchannel_id schid, void *data)
 465 {
 466         struct subchannel *sch;
 467         int ret;
 468
 469         if (cio_is_console(schid))
 470                 sch = cio_get_console_subchannel();
 471         else {
 472                 sch = css_alloc_subchannel(schid);
 473                 if (IS_ERR(sch))
 474                         ret = PTR_ERR(sch);
 475                 else
 476                         ret = 0;
 477                 switch (ret) {
 478                 case 0:
 479                         break;
 480                 case -ENOMEM:
 481                         panic("Out of memory in init_channel_subsystem\n");
 482                 /* -ENXIO: no more subchannels. */
 483                 case -ENXIO:
 484                         return ret;
 485                 /* -EIO: this subchannel set not supported. */
 486                 case -EIO:
 487                         return ret;
 488                 default:
 489                         return 0;
 490                 }
 491         }
 492         /*
 493          * We register ALL valid subchannels in ioinfo, even those
 494          * that have been present before init_channel_subsystem.
 495          * These subchannels can't have been registered yet (kmalloc
 496          * not working) so we do it now. This is true e.g. for the
 497          * console subchannel.
 498          */
 499         css_register_subchannel(sch);
 500         return 0;
 501 }
 502
 503 static void __init
 504 css_generate_pgid(struct channel_subsystem *css, u32 tod_high)
 505 {
 506         if (css_characteristics_avail && css_general_characteristics.mcss) {
 507                 css->global_pgid.pgid_high.ext_cssid.version = 0x80;
 508                 css->global_pgid.pgid_high.ext_cssid.cssid = css->cssid;
 509         } else {
 510 #ifdef CONFIG_SMP
 511                 css->global_pgid.pgid_high.cpu_addr = hard_smp_processor_id();
 512 #else
 513                 css->global_pgid.pgid_high.cpu_addr = 0;
 514 #endif
 515         }
 516         css->global_pgid.cpu_id = ((cpuid_t *) __LC_CPUID)->ident;
 517         css->global_pgid.cpu_model = ((cpuid_t *) __LC_CPUID)->machine;
 518         css->global_pgid.tod_high = tod_high;
 519
 520 }
 521
 522 static void
 523 channel_subsystem_release(struct device *dev)
 524 {
 525         struct channel_subsystem *css;
 526
 527         css = to_css(dev);
 528         mutex_destroy(&css->mutex);
 529         kfree(css);
 530 }
 531
 532 static ssize_t
 533 css_cm_enable_show(struct device *dev, struct device_attribute *attr,
 534                    char *buf)
 535 {
 536         struct channel_subsystem *css = to_css(dev);
 537
 538         if (!css)
 539                 return 0;
 540         return sprintf(buf, "%x\n", css->cm_enabled);
 541 }
 542
 543 static ssize_t
 544 css_cm_enable_store(struct device *dev, struct device_attribute *attr,
 545                     const char *buf, size_t count)
 546 {
 547         struct channel_subsystem *css = to_css(dev);
 548         int ret;
 549
 550         switch (buf[0]) {
 551         case '0':
 552                 ret = css->cm_enabled ? chsc_secm(css, 0) : 0;
 553                 break;
 554         case '1':
 555                 ret = css->cm_enabled ? 0 : chsc_secm(css, 1);
 556                 break;
 557         default:
 558                 ret = -EINVAL;
 559         }
 560         return ret < 0 ? ret : count;
 561 }
 562
 563 static DEVICE_ATTR(cm_enable, 0644, css_cm_enable_show, css_cm_enable_store);
 564
 565 static int __init setup_css(int nr)
 566 {
 567         u32 tod_high;
 568         int ret;
 569
 570         memset(css[nr], 0, sizeof(struct channel_subsystem));
 571         css[nr]->pseudo_subchannel =
 572                 kzalloc(sizeof(*css[nr]->pseudo_subchannel), GFP_KERNEL);
 573         if (!css[nr]->pseudo_subchannel)
 574                 return -ENOMEM;
 575         css[nr]->pseudo_subchannel->dev.parent = &css[nr]->device;
 576         css[nr]->pseudo_subchannel->dev.release = css_subchannel_release;
 577         sprintf(css[nr]->pseudo_subchannel->dev.bus_id, "defunct");
 578         ret = cio_create_sch_lock(css[nr]->pseudo_subchannel);
 579         if (ret) {
 580                 kfree(css[nr]->pseudo_subchannel);
 581                 return ret;
 582         }
 583         mutex_init(&css[nr]->mutex);
 584         css[nr]->valid = 1;
 585         css[nr]->cssid = nr;
 586         sprintf(css[nr]->device.bus_id, "css%x", nr);
 587         css[nr]->device.release = channel_subsystem_release;
 588         tod_high = (u32) (get_clock() >> 32);
 589         css_generate_pgid(css[nr], tod_high);
 590         return 0;
 591 }
 592
 593 /*
 594  * Now that the driver core is running, we can setup our channel subsystem.
 595  * The struct subchannel's are created during probing (except for the
 596  * static console subchannel).
 597  */
 598 static int __init
 599 init_channel_subsystem (void)
 600 {
 601         int ret, i;
 602
 603         if (chsc_determine_css_characteristics() == 0)
 604                 css_characteristics_avail = 1;
 605
 606         if ((ret = bus_register(&css_bus_type)))
 607                 goto out;
 608
 609         /* Try to enable MSS. */
 610         ret = chsc_enable_facility(CHSC_SDA_OC_MSS);
 611         switch (ret) {
 612         case 0: /* Success. */
 613                 max_ssid = __MAX_SSID;
 614                 break;
 615         case -ENOMEM:
 616                 goto out_bus;
 617         default:
 618                 max_ssid = 0;
 619         }
 620         /* Setup css structure. */
 621         for (i = 0; i <= __MAX_CSSID; i++) {
 622                 css[i] = kmalloc(sizeof(struct channel_subsystem), GFP_KERNEL);
 623                 if (!css[i]) {
 624                         ret = -ENOMEM;
 625                         goto out_unregister;
 626                 }
 627                 ret = setup_css(i);
 628                 if (ret)
 629                         goto out_free;
 630                 ret = device_register(&css[i]->device);
 631                 if (ret)
 632                         goto out_free_all;
 633                 if (css_characteristics_avail &&
 634                     css_chsc_characteristics.secm) {
 635                         ret = device_create_file(&css[i]->device,
 636                                                  &dev_attr_cm_enable);
 637                         if (ret)
 638                                 goto out_device;
 639                 }
 640                 ret = device_register(&css[i]->pseudo_subchannel->dev);
 641                 if (ret)
 642                         goto out_file;
 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_file:
 651         device_remove_file(&css[i]->device, &dev_attr_cm_enable);
 652 out_device:
 653         device_unregister(&css[i]->device);
 654 out_free_all:
 655         kfree(css[i]->pseudo_subchannel->lock);
 656         kfree(css[i]->pseudo_subchannel);
 657 out_free:
 658         kfree(css[i]);
 659 out_unregister:
 660         while (i > 0) {
 661                 i--;
 662                 device_unregister(&css[i]->pseudo_subchannel->dev);
 663                 if (css_characteristics_avail && css_chsc_characteristics.secm)
 664                         device_remove_file(&css[i]->device,
 665                                            &dev_attr_cm_enable);
 666                 device_unregister(&css[i]->device);
 667         }
 668 out_bus:
 669         bus_unregister(&css_bus_type);
 670 out:
 671         return ret;
 672 }
 673
 674 int sch_is_pseudo_sch(struct subchannel *sch)
 675 {
 676         return sch == to_css(sch->dev.parent)->pseudo_subchannel;
 677 }
 678
 679 /*
 680  * find a driver for a subchannel. They identify by the subchannel
 681  * type with the exception that the console subchannel driver has its own
 682  * subchannel type although the device is an i/o subchannel
 683  */
 684 static int
 685 css_bus_match (struct device *dev, struct device_driver *drv)
 686 {
 687         struct subchannel *sch = container_of (dev, struct subchannel, dev);
 688         struct css_driver *driver = container_of (drv, struct css_driver, drv);
 689
 690         if (sch->st == driver->subchannel_type)
 691                 return 1;
 692
 693         return 0;
 694 }
 695
 696 static int
 697 css_probe (struct device *dev)
 698 {
 699         struct subchannel *sch;
 700
 701         sch = to_subchannel(dev);
 702         sch->driver = container_of (dev->driver, struct css_driver, drv);
 703         return (sch->driver->probe ? sch->driver->probe(sch) : 0);
 704 }
 705
 706 static int
 707 css_remove (struct device *dev)
 708 {
 709         struct subchannel *sch;
 710
 711         sch = to_subchannel(dev);
 712         return (sch->driver->remove ? sch->driver->remove(sch) : 0);
 713 }
 714
 715 static void
 716 css_shutdown (struct device *dev)
 717 {
 718         struct subchannel *sch;
 719
 720         sch = to_subchannel(dev);
 721         if (sch->driver->shutdown)
 722                 sch->driver->shutdown(sch);
 723 }
 724
 725 struct bus_type css_bus_type = {
 726         .name     = "css",
 727         .match    = css_bus_match,
 728         .probe    = css_probe,
 729         .remove   = css_remove,
 730         .shutdown = css_shutdown,
 731 };
 732
 733 subsys_initcall(init_channel_subsystem);
 734
 735 MODULE_LICENSE("GPL");
 736 EXPORT_SYMBOL(css_bus_type);
 737 EXPORT_SYMBOL_GPL(css_characteristics_avail);