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 #include <linux/reboot.h>
  17
  18 #include "css.h"
  19 #include "cio.h"
  20 #include "cio_debug.h"
  21 #include "ioasm.h"
  22 #include "chsc.h"
  23 #include "device.h"
  24 #include "idset.h"
  25 #include "chp.h"
  26
  27 int css_init_done = 0;
  28 static int need_reprobe = 0;
  29 static int max_ssid = 0;
  30
  31 struct channel_subsystem *channel_subsystems[__MAX_CSSID + 1];
  32
  33 int css_characteristics_avail = 0;
  34
  35 int
  36 for_each_subchannel(int(*fn)(struct subchannel_id, void *), void *data)
  37 {
  38         struct subchannel_id schid;
  39         int ret;
  40
  41         init_subchannel_id(&schid);
  42         ret = -ENODEV;
  43         do {
  44                 do {
  45                         ret = fn(schid, data);
  46                         if (ret)
  47                                 break;
  48                 } while (schid.sch_no++ < __MAX_SUBCHANNEL);
  49                 schid.sch_no = 0;
  50         } while (schid.ssid++ < max_ssid);
  51         return ret;
  52 }
  53
  54 static struct subchannel *
  55 css_alloc_subchannel(struct subchannel_id schid)
  56 {
  57         struct subchannel *sch;
  58         int ret;
  59
  60         sch = kmalloc (sizeof (*sch), GFP_KERNEL | GFP_DMA);
  61         if (sch == NULL)
  62                 return ERR_PTR(-ENOMEM);
  63         ret = cio_validate_subchannel (sch, schid);
  64         if (ret < 0) {
  65                 kfree(sch);
  66                 return ERR_PTR(ret);
  67         }
  68
  69         if (sch->st != SUBCHANNEL_TYPE_IO) {
  70                 /* For now we ignore all non-io subchannels. */
  71                 kfree(sch);
  72                 return ERR_PTR(-EINVAL);
  73         }
  74
  75         /*
  76          * Set intparm to subchannel address.
  77          * This is fine even on 64bit since the subchannel is always located
  78          * under 2G.
  79          */
  80         sch->schib.pmcw.intparm = (u32)(addr_t)sch;
  81         ret = cio_modify(sch);
  82         if (ret) {
  83                 kfree(sch->lock);
  84                 kfree(sch);
  85                 return ERR_PTR(ret);
  86         }
  87         return sch;
  88 }
  89
  90 static void
  91 css_free_subchannel(struct subchannel *sch)
  92 {
  93         if (sch) {
  94                 /* Reset intparm to zeroes. */
  95                 sch->schib.pmcw.intparm = 0;
  96                 cio_modify(sch);
  97                 kfree(sch->lock);
  98                 kfree(sch);
  99         }
 100 }
 101
 102 static void
 103 css_subchannel_release(struct device *dev)
 104 {
 105         struct subchannel *sch;
 106
 107         sch = to_subchannel(dev);
 108         if (!cio_is_console(sch->schid)) {
 109                 kfree(sch->lock);
 110                 kfree(sch);
 111         }
 112 }
 113
 114 static 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 void ssd_from_pmcw(struct chsc_ssd_info *ssd, struct pmcw *pmcw)
 132 {
 133         int i;
 134         int mask;
 135
 136         memset(ssd, 0, sizeof(struct chsc_ssd_info));
 137         ssd->path_mask = pmcw->pim;
 138         for (i = 0; i < 8; i++) {
 139                 mask = 0x80 >> i;
 140                 if (pmcw->pim & mask) {
 141                         chp_id_init(&ssd->chpid[i]);
 142                         ssd->chpid[i].id = pmcw->chpid[i];
 143                 }
 144         }
 145 }
 146
 147 static void ssd_register_chpids(struct chsc_ssd_info *ssd)
 148 {
 149         int i;
 150         int mask;
 151
 152         for (i = 0; i < 8; i++) {
 153                 mask = 0x80 >> i;
 154                 if (ssd->path_mask & mask)
 155                         if (!chp_is_registered(ssd->chpid[i]))
 156                                 chp_new(ssd->chpid[i]);
 157         }
 158 }
 159
 160 void css_update_ssd_info(struct subchannel *sch)
 161 {
 162         int ret;
 163
 164         if (cio_is_console(sch->schid)) {
 165                 /* Console is initialized too early for functions requiring
 166                  * memory allocation. */
 167                 ssd_from_pmcw(&sch->ssd_info, &sch->schib.pmcw);
 168         } else {
 169                 ret = chsc_get_ssd_info(sch->schid, &sch->ssd_info);
 170                 if (ret)
 171                         ssd_from_pmcw(&sch->ssd_info, &sch->schib.pmcw);
 172                 ssd_register_chpids(&sch->ssd_info);
 173         }
 174 }
 175
 176 static int css_register_subchannel(struct subchannel *sch)
 177 {
 178         int ret;
 179
 180         /* Initialize the subchannel structure */
 181         sch->dev.parent = &channel_subsystems[0]->device;
 182         sch->dev.bus = &css_bus_type;
 183         sch->dev.release = &css_subchannel_release;
 184         sch->dev.groups = subch_attr_groups;
 185         /*
 186          * We don't want to generate uevents for I/O subchannels that don't
 187          * have a working ccw device behind them since they will be
 188          * unregistered before they can be used anyway, so we delay the add
 189          * uevent until after device recognition was successful.
 190          */
 191         if (!cio_is_console(sch->schid))
 192                 /* Console is special, no need to suppress. */
 193                 sch->dev.uevent_suppress = 1;
 194         css_update_ssd_info(sch);
 195         /* make it known to the system */
 196         ret = css_sch_device_register(sch);
 197         if (ret) {
 198                 CIO_MSG_EVENT(0, "Could not register sch 0.%x.%04x: %d\n",
 199                               sch->schid.ssid, sch->schid.sch_no, ret);
 200                 return ret;
 201         }
 202         return ret;
 203 }
 204
 205 static int css_probe_device(struct subchannel_id schid)
 206 {
 207         int ret;
 208         struct subchannel *sch;
 209
 210         sch = css_alloc_subchannel(schid);
 211         if (IS_ERR(sch))
 212                 return PTR_ERR(sch);
 213         ret = css_register_subchannel(sch);
 214         if (ret)
 215                 css_free_subchannel(sch);
 216         return ret;
 217 }
 218
 219 static int
 220 check_subchannel(struct device * dev, void * data)
 221 {
 222         struct subchannel *sch;
 223         struct subchannel_id *schid = data;
 224
 225         sch = to_subchannel(dev);
 226         return schid_equal(&sch->schid, schid);
 227 }
 228
 229 struct subchannel *
 230 get_subchannel_by_schid(struct subchannel_id schid)
 231 {
 232         struct device *dev;
 233
 234         dev = bus_find_device(&css_bus_type, NULL,
 235                               &schid, check_subchannel);
 236
 237         return dev ? to_subchannel(dev) : NULL;
 238 }
 239
 240 /**
 241  * css_sch_is_valid() - check if a subchannel is valid
 242  * @schib: subchannel information block for the subchannel
 243  */
 244 int css_sch_is_valid(struct schib *schib)
 245 {
 246         if ((schib->pmcw.st == SUBCHANNEL_TYPE_IO) && !schib->pmcw.dnv)
 247                 return 0;
 248         return 1;
 249 }
 250 EXPORT_SYMBOL_GPL(css_sch_is_valid);
 251
 252 static int css_get_subchannel_status(struct subchannel *sch)
 253 {
 254         struct schib schib;
 255
 256         if (stsch(sch->schid, &schib))
 257                 return CIO_GONE;
 258         if (!css_sch_is_valid(&schib))
 259                 return CIO_GONE;
 260         if (sch->schib.pmcw.dnv && (schib.pmcw.dev != sch->schib.pmcw.dev))
 261                 return CIO_REVALIDATE;
 262         if (!sch->lpm)
 263                 return CIO_NO_PATH;
 264         return CIO_OPER;
 265 }
 266
 267 static int css_evaluate_known_subchannel(struct subchannel *sch, int slow)
 268 {
 269         int event, ret, disc;
 270         unsigned long flags;
 271         enum { NONE, UNREGISTER, UNREGISTER_PROBE, REPROBE } action;
 272
 273         spin_lock_irqsave(sch->lock, flags);
 274         disc = device_is_disconnected(sch);
 275         if (disc && slow) {
 276                 /* Disconnected devices are evaluated directly only.*/
 277                 spin_unlock_irqrestore(sch->lock, flags);
 278                 return 0;
 279         }
 280         /* No interrupt after machine check - kill pending timers. */
 281         device_kill_pending_timer(sch);
 282         if (!disc && !slow) {
 283                 /* Non-disconnected devices are evaluated on the slow path. */
 284                 spin_unlock_irqrestore(sch->lock, flags);
 285                 return -EAGAIN;
 286         }
 287         event = css_get_subchannel_status(sch);
 288         CIO_MSG_EVENT(4, "Evaluating schid 0.%x.%04x, event %d, %s, %s path.\n",
 289                       sch->schid.ssid, sch->schid.sch_no, event,
 290                       disc ? "disconnected" : "normal",
 291                       slow ? "slow" : "fast");
 292         /* Analyze subchannel status. */
 293         action = NONE;
 294         switch (event) {
 295         case CIO_NO_PATH:
 296                 if (disc) {
 297                         /* Check if paths have become available. */
 298                         action = REPROBE;
 299                         break;
 300                 }
 301                 /* fall through */
 302         case CIO_GONE:
 303                 /* Prevent unwanted effects when opening lock. */
 304                 cio_disable_subchannel(sch);
 305                 device_set_disconnected(sch);
 306                 /* Ask driver what to do with device. */
 307                 action = UNREGISTER;
 308                 if (sch->driver && sch->driver->notify) {
 309                         spin_unlock_irqrestore(sch->lock, flags);
 310                         ret = sch->driver->notify(sch, event);
 311                         spin_lock_irqsave(sch->lock, flags);
 312                         if (ret)
 313                                 action = NONE;
 314                 }
 315                 break;
 316         case CIO_REVALIDATE:
 317                 /* Device will be removed, so no notify necessary. */
 318                 if (disc)
 319                         /* Reprobe because immediate unregister might block. */
 320                         action = REPROBE;
 321                 else
 322                         action = UNREGISTER_PROBE;
 323                 break;
 324         case CIO_OPER:
 325                 if (disc)
 326                         /* Get device operational again. */
 327                         action = REPROBE;
 328                 break;
 329         }
 330         /* Perform action. */
 331         ret = 0;
 332         switch (action) {
 333         case UNREGISTER:
 334         case UNREGISTER_PROBE:
 335                 /* Unregister device (will use subchannel lock). */
 336                 spin_unlock_irqrestore(sch->lock, flags);
 337                 css_sch_device_unregister(sch);
 338                 spin_lock_irqsave(sch->lock, flags);
 339
 340                 /* Reset intparm to zeroes. */
 341                 sch->schib.pmcw.intparm = 0;
 342                 cio_modify(sch);
 343                 break;
 344         case REPROBE:
 345                 device_trigger_reprobe(sch);
 346                 break;
 347         default:
 348                 break;
 349         }
 350         spin_unlock_irqrestore(sch->lock, flags);
 351         /* Probe if necessary. */
 352         if (action == UNREGISTER_PROBE)
 353                 ret = css_probe_device(sch->schid);
 354
 355         return ret;
 356 }
 357
 358 static int css_evaluate_new_subchannel(struct subchannel_id schid, int slow)
 359 {
 360         struct schib schib;
 361
 362         if (!slow) {
 363                 /* Will be done on the slow path. */
 364                 return -EAGAIN;
 365         }
 366         if (stsch_err(schid, &schib) || !css_sch_is_valid(&schib)) {
 367                 /* Unusable - ignore. */
 368                 return 0;
 369         }
 370         CIO_MSG_EVENT(4, "Evaluating schid 0.%x.%04x, event %d, unknown, "
 371                          "slow path.\n", schid.ssid, schid.sch_no, CIO_OPER);
 372
 373         return css_probe_device(schid);
 374 }
 375
 376 static void css_evaluate_subchannel(struct subchannel_id schid, int slow)
 377 {
 378         struct subchannel *sch;
 379         int ret;
 380
 381         sch = get_subchannel_by_schid(schid);
 382         if (sch) {
 383                 ret = css_evaluate_known_subchannel(sch, slow);
 384                 put_device(&sch->dev);
 385         } else
 386                 ret = css_evaluate_new_subchannel(schid, slow);
 387         if (ret == -EAGAIN)
 388                 css_schedule_eval(schid);
 389 }
 390
 391 static struct idset *slow_subchannel_set;
 392 static spinlock_t slow_subchannel_lock;
 393
 394 static int __init slow_subchannel_init(void)
 395 {
 396         spin_lock_init(&slow_subchannel_lock);
 397         slow_subchannel_set = idset_sch_new();
 398         if (!slow_subchannel_set) {
 399                 CIO_MSG_EVENT(0, "could not allocate slow subchannel set\n");
 400                 return -ENOMEM;
 401         }
 402         return 0;
 403 }
 404
 405 static void css_slow_path_func(struct work_struct *unused)
 406 {
 407         struct subchannel_id schid;
 408
 409         CIO_TRACE_EVENT(4, "slowpath");
 410         spin_lock_irq(&slow_subchannel_lock);
 411         init_subchannel_id(&schid);
 412         while (idset_sch_get_first(slow_subchannel_set, &schid)) {
 413                 idset_sch_del(slow_subchannel_set, schid);
 414                 spin_unlock_irq(&slow_subchannel_lock);
 415                 css_evaluate_subchannel(schid, 1);
 416                 spin_lock_irq(&slow_subchannel_lock);
 417         }
 418         spin_unlock_irq(&slow_subchannel_lock);
 419 }
 420
 421 static DECLARE_WORK(slow_path_work, css_slow_path_func);
 422 struct workqueue_struct *slow_path_wq;
 423
 424 void css_schedule_eval(struct subchannel_id schid)
 425 {
 426         unsigned long flags;
 427
 428         spin_lock_irqsave(&slow_subchannel_lock, flags);
 429         idset_sch_add(slow_subchannel_set, schid);
 430         queue_work(slow_path_wq, &slow_path_work);
 431         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 432 }
 433
 434 void css_schedule_eval_all(void)
 435 {
 436         unsigned long flags;
 437
 438         spin_lock_irqsave(&slow_subchannel_lock, flags);
 439         idset_fill(slow_subchannel_set);
 440         queue_work(slow_path_wq, &slow_path_work);
 441         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 442 }
 443
 444 /* Reprobe subchannel if unregistered. */
 445 static int reprobe_subchannel(struct subchannel_id schid, void *data)
 446 {
 447         struct subchannel *sch;
 448         int ret;
 449
 450         CIO_MSG_EVENT(6, "cio: reprobe 0.%x.%04x\n",
 451                       schid.ssid, schid.sch_no);
 452         if (need_reprobe)
 453                 return -EAGAIN;
 454
 455         sch = get_subchannel_by_schid(schid);
 456         if (sch) {
 457                 /* Already known. */
 458                 put_device(&sch->dev);
 459                 return 0;
 460         }
 461
 462         ret = css_probe_device(schid);
 463         switch (ret) {
 464         case 0:
 465                 break;
 466         case -ENXIO:
 467         case -ENOMEM:
 468         case -EIO:
 469                 /* These should abort looping */
 470                 break;
 471         default:
 472                 ret = 0;
 473         }
 474
 475         return ret;
 476 }
 477
 478 /* Work function used to reprobe all unregistered subchannels. */
 479 static void reprobe_all(struct work_struct *unused)
 480 {
 481         int ret;
 482
 483         CIO_MSG_EVENT(2, "reprobe start\n");
 484
 485         need_reprobe = 0;
 486         /* Make sure initial subchannel scan is done. */
 487         wait_event(ccw_device_init_wq,
 488                    atomic_read(&ccw_device_init_count) == 0);
 489         ret = for_each_subchannel(reprobe_subchannel, NULL);
 490
 491         CIO_MSG_EVENT(2, "reprobe done (rc=%d, need_reprobe=%d)\n", ret,
 492                       need_reprobe);
 493 }
 494
 495 static DECLARE_WORK(css_reprobe_work, reprobe_all);
 496
 497 /* Schedule reprobing of all unregistered subchannels. */
 498 void css_schedule_reprobe(void)
 499 {
 500         need_reprobe = 1;
 501         queue_work(slow_path_wq, &css_reprobe_work);
 502 }
 503
 504 EXPORT_SYMBOL_GPL(css_schedule_reprobe);
 505
 506 /*
 507  * Called from the machine check handler for subchannel report words.
 508  */
 509 void css_process_crw(int rsid1, int rsid2)
 510 {
 511         struct subchannel_id mchk_schid;
 512
 513         CIO_CRW_EVENT(2, "source is subchannel %04X, subsystem id %x\n",
 514                       rsid1, rsid2);
 515         init_subchannel_id(&mchk_schid);
 516         mchk_schid.sch_no = rsid1;
 517         if (rsid2 != 0)
 518                 mchk_schid.ssid = (rsid2 >> 8) & 3;
 519
 520         /*
 521          * Since we are always presented with IPI in the CRW, we have to
 522          * use stsch() to find out if the subchannel in question has come
 523          * or gone.
 524          */
 525         css_evaluate_subchannel(mchk_schid, 0);
 526 }
 527
 528 static int __init
 529 __init_channel_subsystem(struct subchannel_id schid, void *data)
 530 {
 531         struct subchannel *sch;
 532         int ret;
 533
 534         if (cio_is_console(schid))
 535                 sch = cio_get_console_subchannel();
 536         else {
 537                 sch = css_alloc_subchannel(schid);
 538                 if (IS_ERR(sch))
 539                         ret = PTR_ERR(sch);
 540                 else
 541                         ret = 0;
 542                 switch (ret) {
 543                 case 0:
 544                         break;
 545                 case -ENOMEM:
 546                         panic("Out of memory in init_channel_subsystem\n");
 547                 /* -ENXIO: no more subchannels. */
 548                 case -ENXIO:
 549                         return ret;
 550                 /* -EIO: this subchannel set not supported. */
 551                 case -EIO:
 552                         return ret;
 553                 default:
 554                         return 0;
 555                 }
 556         }
 557         /*
 558          * We register ALL valid subchannels in ioinfo, even those
 559          * that have been present before init_channel_subsystem.
 560          * These subchannels can't have been registered yet (kmalloc
 561          * not working) so we do it now. This is true e.g. for the
 562          * console subchannel.
 563          */
 564         css_register_subchannel(sch);
 565         return 0;
 566 }
 567
 568 static void __init
 569 css_generate_pgid(struct channel_subsystem *css, u32 tod_high)
 570 {
 571         if (css_characteristics_avail && css_general_characteristics.mcss) {
 572                 css->global_pgid.pgid_high.ext_cssid.version = 0x80;
 573                 css->global_pgid.pgid_high.ext_cssid.cssid = css->cssid;
 574         } else {
 575 #ifdef CONFIG_SMP
 576                 css->global_pgid.pgid_high.cpu_addr = hard_smp_processor_id();
 577 #else
 578                 css->global_pgid.pgid_high.cpu_addr = 0;
 579 #endif
 580         }
 581         css->global_pgid.cpu_id = ((cpuid_t *) __LC_CPUID)->ident;
 582         css->global_pgid.cpu_model = ((cpuid_t *) __LC_CPUID)->machine;
 583         css->global_pgid.tod_high = tod_high;
 584
 585 }
 586
 587 static void
 588 channel_subsystem_release(struct device *dev)
 589 {
 590         struct channel_subsystem *css;
 591
 592         css = to_css(dev);
 593         mutex_destroy(&css->mutex);
 594         kfree(css);
 595 }
 596
 597 static ssize_t
 598 css_cm_enable_show(struct device *dev, struct device_attribute *attr,
 599                    char *buf)
 600 {
 601         struct channel_subsystem *css = to_css(dev);
 602
 603         if (!css)
 604                 return 0;
 605         return sprintf(buf, "%x\n", css->cm_enabled);
 606 }
 607
 608 static ssize_t
 609 css_cm_enable_store(struct device *dev, struct device_attribute *attr,
 610                     const char *buf, size_t count)
 611 {
 612         struct channel_subsystem *css = to_css(dev);
 613         int ret;
 614
 615         switch (buf[0]) {
 616         case '0':
 617                 ret = css->cm_enabled ? chsc_secm(css, 0) : 0;
 618                 break;
 619         case '1':
 620                 ret = css->cm_enabled ? 0 : chsc_secm(css, 1);
 621                 break;
 622         default:
 623                 ret = -EINVAL;
 624         }
 625         return ret < 0 ? ret : count;
 626 }
 627
 628 static DEVICE_ATTR(cm_enable, 0644, css_cm_enable_show, css_cm_enable_store);
 629
 630 static int __init setup_css(int nr)
 631 {
 632         u32 tod_high;
 633         int ret;
 634         struct channel_subsystem *css;
 635
 636         css = channel_subsystems[nr];
 637         memset(css, 0, sizeof(struct channel_subsystem));
 638         css->pseudo_subchannel =
 639                 kzalloc(sizeof(*css->pseudo_subchannel), GFP_KERNEL);
 640         if (!css->pseudo_subchannel)
 641                 return -ENOMEM;
 642         css->pseudo_subchannel->dev.parent = &css->device;
 643         css->pseudo_subchannel->dev.release = css_subchannel_release;
 644         sprintf(css->pseudo_subchannel->dev.bus_id, "defunct");
 645         ret = cio_create_sch_lock(css->pseudo_subchannel);
 646         if (ret) {
 647                 kfree(css->pseudo_subchannel);
 648                 return ret;
 649         }
 650         mutex_init(&css->mutex);
 651         css->valid = 1;
 652         css->cssid = nr;
 653         sprintf(css->device.bus_id, "css%x", nr);
 654         css->device.release = channel_subsystem_release;
 655         tod_high = (u32) (get_clock() >> 32);
 656         css_generate_pgid(css, tod_high);
 657         return 0;
 658 }
 659
 660 static int css_reboot_event(struct notifier_block *this,
 661                             unsigned long event,
 662                             void *ptr)
 663 {
 664         int ret, i;
 665
 666         ret = NOTIFY_DONE;
 667         for (i = 0; i <= __MAX_CSSID; i++) {
 668                 struct channel_subsystem *css;
 669
 670                 css = channel_subsystems[i];
 671                 if (css->cm_enabled)
 672                         if (chsc_secm(css, 0))
 673                                 ret = NOTIFY_BAD;
 674         }
 675
 676         return ret;
 677 }
 678
 679 static struct notifier_block css_reboot_notifier = {
 680         .notifier_call = css_reboot_event,
 681 };
 682
 683 /*
 684  * Now that the driver core is running, we can setup our channel subsystem.
 685  * The struct subchannel's are created during probing (except for the
 686  * static console subchannel).
 687  */
 688 static int __init
 689 init_channel_subsystem (void)
 690 {
 691         int ret, i;
 692
 693         ret = chsc_determine_css_characteristics();
 694         if (ret == -ENOMEM)
 695                 goto out; /* No need to continue. */
 696         if (ret == 0)
 697                 css_characteristics_avail = 1;
 698
 699         ret = chsc_alloc_sei_area();
 700         if (ret)
 701                 goto out;
 702
 703         ret = slow_subchannel_init();
 704         if (ret)
 705                 goto out;
 706
 707         if ((ret = bus_register(&css_bus_type)))
 708                 goto out;
 709
 710         /* Try to enable MSS. */
 711         ret = chsc_enable_facility(CHSC_SDA_OC_MSS);
 712         switch (ret) {
 713         case 0: /* Success. */
 714                 max_ssid = __MAX_SSID;
 715                 break;
 716         case -ENOMEM:
 717                 goto out_bus;
 718         default:
 719                 max_ssid = 0;
 720         }
 721         /* Setup css structure. */
 722         for (i = 0; i <= __MAX_CSSID; i++) {
 723                 struct channel_subsystem *css;
 724
 725                 css = kmalloc(sizeof(struct channel_subsystem), GFP_KERNEL);
 726                 if (!css) {
 727                         ret = -ENOMEM;
 728                         goto out_unregister;
 729                 }
 730                 channel_subsystems[i] = css;
 731                 ret = setup_css(i);
 732                 if (ret)
 733                         goto out_free;
 734                 ret = device_register(&css->device);
 735                 if (ret)
 736                         goto out_free_all;
 737                 if (css_characteristics_avail &&
 738                     css_chsc_characteristics.secm) {
 739                         ret = device_create_file(&css->device,
 740                                                  &dev_attr_cm_enable);
 741                         if (ret)
 742                                 goto out_device;
 743                 }
 744                 ret = device_register(&css->pseudo_subchannel->dev);
 745                 if (ret)
 746                         goto out_file;
 747         }
 748         ret = register_reboot_notifier(&css_reboot_notifier);
 749         if (ret)
 750                 goto out_pseudo;
 751         css_init_done = 1;
 752
 753         ctl_set_bit(6, 28);
 754
 755         for_each_subchannel(__init_channel_subsystem, NULL);
 756         return 0;
 757 out_pseudo:
 758         device_unregister(&channel_subsystems[i]->pseudo_subchannel->dev);
 759 out_file:
 760         device_remove_file(&channel_subsystems[i]->device,
 761                            &dev_attr_cm_enable);
 762 out_device:
 763         device_unregister(&channel_subsystems[i]->device);
 764 out_free_all:
 765         kfree(channel_subsystems[i]->pseudo_subchannel->lock);
 766         kfree(channel_subsystems[i]->pseudo_subchannel);
 767 out_free:
 768         kfree(channel_subsystems[i]);
 769 out_unregister:
 770         while (i > 0) {
 771                 struct channel_subsystem *css;
 772
 773                 i--;
 774                 css = channel_subsystems[i];
 775                 device_unregister(&css->pseudo_subchannel->dev);
 776                 if (css_characteristics_avail && css_chsc_characteristics.secm)
 777                         device_remove_file(&css->device,
 778                                            &dev_attr_cm_enable);
 779                 device_unregister(&css->device);
 780         }
 781 out_bus:
 782         bus_unregister(&css_bus_type);
 783 out:
 784         chsc_free_sei_area();
 785         kfree(slow_subchannel_set);
 786         printk(KERN_WARNING"cio: failed to initialize css driver (%d)!\n",
 787                ret);
 788         return ret;
 789 }
 790
 791 int sch_is_pseudo_sch(struct subchannel *sch)
 792 {
 793         return sch == to_css(sch->dev.parent)->pseudo_subchannel;
 794 }
 795
 796 /*
 797  * find a driver for a subchannel. They identify by the subchannel
 798  * type with the exception that the console subchannel driver has its own
 799  * subchannel type although the device is an i/o subchannel
 800  */
 801 static int
 802 css_bus_match (struct device *dev, struct device_driver *drv)
 803 {
 804         struct subchannel *sch = to_subchannel(dev);
 805         struct css_driver *driver = to_cssdriver(drv);
 806
 807         if (sch->st == driver->subchannel_type)
 808                 return 1;
 809
 810         return 0;
 811 }
 812
 813 static int css_probe(struct device *dev)
 814 {
 815         struct subchannel *sch;
 816         int ret;
 817
 818         sch = to_subchannel(dev);
 819         sch->driver = to_cssdriver(dev->driver);
 820         ret = sch->driver->probe ? sch->driver->probe(sch) : 0;
 821         if (ret)
 822                 sch->driver = NULL;
 823         return ret;
 824 }
 825
 826 static int css_remove(struct device *dev)
 827 {
 828         struct subchannel *sch;
 829         int ret;
 830
 831         sch = to_subchannel(dev);
 832         ret = sch->driver->remove ? sch->driver->remove(sch) : 0;
 833         sch->driver = NULL;
 834         return ret;
 835 }
 836
 837 static void css_shutdown(struct device *dev)
 838 {
 839         struct subchannel *sch;
 840
 841         sch = to_subchannel(dev);
 842         if (sch->driver && sch->driver->shutdown)
 843                 sch->driver->shutdown(sch);
 844 }
 845
 846 struct bus_type css_bus_type = {
 847         .name     = "css",
 848         .match    = css_bus_match,
 849         .probe    = css_probe,
 850         .remove   = css_remove,
 851         .shutdown = css_shutdown,
 852 };
 853
 854 /**
 855  * css_driver_register - register a css driver
 856  * @cdrv: css driver to register
 857  *
 858  * This is mainly a wrapper around driver_register that sets name
 859  * and bus_type in the embedded struct device_driver correctly.
 860  */
 861 int css_driver_register(struct css_driver *cdrv)
 862 {
 863         cdrv->drv.name = cdrv->name;
 864         cdrv->drv.bus = &css_bus_type;
 865         cdrv->drv.owner = cdrv->owner;
 866         return driver_register(&cdrv->drv);
 867 }
 868 EXPORT_SYMBOL_GPL(css_driver_register);
 869
 870 /**
 871  * css_driver_unregister - unregister a css driver
 872  * @cdrv: css driver to unregister
 873  *
 874  * This is a wrapper around driver_unregister.
 875  */
 876 void css_driver_unregister(struct css_driver *cdrv)
 877 {
 878         driver_unregister(&cdrv->drv);
 879 }
 880 EXPORT_SYMBOL_GPL(css_driver_unregister);
 881
 882 subsys_initcall(init_channel_subsystem);
 883
 884 MODULE_LICENSE("GPL");
 885 EXPORT_SYMBOL(css_bus_type);
 886 EXPORT_SYMBOL_GPL(css_characteristics_avail);