drivers/s390/cio/css.c

   1 /*
   2  *  drivers/s390/cio/css.c
   3  *  driver for channel subsystem
   4  *
   5  *    Copyright IBM Corp. 2002,2008
   6  *    Author(s): Arnd Bergmann (arndb@de.ibm.com)
   7  *               Cornelia Huck (cornelia.huck@de.ibm.com)
   8  */
   9 #include <linux/module.h>
  10 #include <linux/init.h>
  11 #include <linux/device.h>
  12 #include <linux/slab.h>
  13 #include <linux/errno.h>
  14 #include <linux/list.h>
  15 #include <linux/reboot.h>
  16 #include <asm/isc.h>
  17
  18 #include "../s390mach.h"
  19 #include "css.h"
  20 #include "cio.h"
  21 #include "cio_debug.h"
  22 #include "ioasm.h"
  23 #include "chsc.h"
  24 #include "device.h"
  25 #include "idset.h"
  26 #include "chp.h"
  27
  28 int css_init_done = 0;
  29 static int need_reprobe = 0;
  30 static int max_ssid = 0;
  31
  32 struct channel_subsystem *channel_subsystems[__MAX_CSSID + 1];
  33
  34 int
  35 for_each_subchannel(int(*fn)(struct subchannel_id, void *), void *data)
  36 {
  37         struct subchannel_id schid;
  38         int ret;
  39
  40         init_subchannel_id(&schid);
  41         ret = -ENODEV;
  42         do {
  43                 do {
  44                         ret = fn(schid, data);
  45                         if (ret)
  46                                 break;
  47                 } while (schid.sch_no++ < __MAX_SUBCHANNEL);
  48                 schid.sch_no = 0;
  49         } while (schid.ssid++ < max_ssid);
  50         return ret;
  51 }
  52
  53 struct cb_data {
  54         void *data;
  55         struct idset *set;
  56         int (*fn_known_sch)(struct subchannel *, void *);
  57         int (*fn_unknown_sch)(struct subchannel_id, void *);
  58 };
  59
  60 static int call_fn_known_sch(struct device *dev, void *data)
  61 {
  62         struct subchannel *sch = to_subchannel(dev);
  63         struct cb_data *cb = data;
  64         int rc = 0;
  65
  66         idset_sch_del(cb->set, sch->schid);
  67         if (cb->fn_known_sch)
  68                 rc = cb->fn_known_sch(sch, cb->data);
  69         return rc;
  70 }
  71
  72 static int call_fn_unknown_sch(struct subchannel_id schid, void *data)
  73 {
  74         struct cb_data *cb = data;
  75         int rc = 0;
  76
  77         if (idset_sch_contains(cb->set, schid))
  78                 rc = cb->fn_unknown_sch(schid, cb->data);
  79         return rc;
  80 }
  81
  82 int for_each_subchannel_staged(int (*fn_known)(struct subchannel *, void *),
  83                                int (*fn_unknown)(struct subchannel_id,
  84                                void *), void *data)
  85 {
  86         struct cb_data cb;
  87         int rc;
  88
  89         cb.set = idset_sch_new();
  90         if (!cb.set)
  91                 return -ENOMEM;
  92         idset_fill(cb.set);
  93         cb.data = data;
  94         cb.fn_known_sch = fn_known;
  95         cb.fn_unknown_sch = fn_unknown;
  96         /* Process registered subchannels. */
  97         rc = bus_for_each_dev(&css_bus_type, NULL, &cb, call_fn_known_sch);
  98         if (rc)
  99                 goto out;
 100         /* Process unregistered subchannels. */
 101         if (fn_unknown)
 102                 rc = for_each_subchannel(call_fn_unknown_sch, &cb);
 103 out:
 104         idset_free(cb.set);
 105
 106         return rc;
 107 }
 108
 109 static struct subchannel *
 110 css_alloc_subchannel(struct subchannel_id schid)
 111 {
 112         struct subchannel *sch;
 113         int ret;
 114
 115         sch = kmalloc (sizeof (*sch), GFP_KERNEL | GFP_DMA);
 116         if (sch == NULL)
 117                 return ERR_PTR(-ENOMEM);
 118         ret = cio_validate_subchannel (sch, schid);
 119         if (ret < 0) {
 120                 kfree(sch);
 121                 return ERR_PTR(ret);
 122         }
 123         return sch;
 124 }
 125
 126 static void
 127 css_free_subchannel(struct subchannel *sch)
 128 {
 129         if (sch) {
 130                 /* Reset intparm to zeroes. */
 131                 sch->config.intparm = 0;
 132                 cio_commit_config(sch);
 133                 kfree(sch->lock);
 134                 kfree(sch);
 135         }
 136 }
 137
 138 static void
 139 css_subchannel_release(struct device *dev)
 140 {
 141         struct subchannel *sch;
 142
 143         sch = to_subchannel(dev);
 144         if (!cio_is_console(sch->schid)) {
 145                 kfree(sch->lock);
 146                 kfree(sch);
 147         }
 148 }
 149
 150 static int css_sch_device_register(struct subchannel *sch)
 151 {
 152         int ret;
 153
 154         mutex_lock(&sch->reg_mutex);
 155         ret = device_register(&sch->dev);
 156         mutex_unlock(&sch->reg_mutex);
 157         return ret;
 158 }
 159
 160 /**
 161  * css_sch_device_unregister - unregister a subchannel
 162  * @sch: subchannel to be unregistered
 163  */
 164 void css_sch_device_unregister(struct subchannel *sch)
 165 {
 166         mutex_lock(&sch->reg_mutex);
 167         if (device_is_registered(&sch->dev))
 168                 device_unregister(&sch->dev);
 169         mutex_unlock(&sch->reg_mutex);
 170 }
 171 EXPORT_SYMBOL_GPL(css_sch_device_unregister);
 172
 173 static void ssd_from_pmcw(struct chsc_ssd_info *ssd, struct pmcw *pmcw)
 174 {
 175         int i;
 176         int mask;
 177
 178         memset(ssd, 0, sizeof(struct chsc_ssd_info));
 179         ssd->path_mask = pmcw->pim;
 180         for (i = 0; i < 8; i++) {
 181                 mask = 0x80 >> i;
 182                 if (pmcw->pim & mask) {
 183                         chp_id_init(&ssd->chpid[i]);
 184                         ssd->chpid[i].id = pmcw->chpid[i];
 185                 }
 186         }
 187 }
 188
 189 static void ssd_register_chpids(struct chsc_ssd_info *ssd)
 190 {
 191         int i;
 192         int mask;
 193
 194         for (i = 0; i < 8; i++) {
 195                 mask = 0x80 >> i;
 196                 if (ssd->path_mask & mask)
 197                         if (!chp_is_registered(ssd->chpid[i]))
 198                                 chp_new(ssd->chpid[i]);
 199         }
 200 }
 201
 202 void css_update_ssd_info(struct subchannel *sch)
 203 {
 204         int ret;
 205
 206         if (cio_is_console(sch->schid)) {
 207                 /* Console is initialized too early for functions requiring
 208                  * memory allocation. */
 209                 ssd_from_pmcw(&sch->ssd_info, &sch->schib.pmcw);
 210         } else {
 211                 ret = chsc_get_ssd_info(sch->schid, &sch->ssd_info);
 212                 if (ret)
 213                         ssd_from_pmcw(&sch->ssd_info, &sch->schib.pmcw);
 214                 ssd_register_chpids(&sch->ssd_info);
 215         }
 216 }
 217
 218 static ssize_t type_show(struct device *dev, struct device_attribute *attr,
 219                          char *buf)
 220 {
 221         struct subchannel *sch = to_subchannel(dev);
 222
 223         return sprintf(buf, "%01x\n", sch->st);
 224 }
 225
 226 static DEVICE_ATTR(type, 0444, type_show, NULL);
 227
 228 static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
 229                              char *buf)
 230 {
 231         struct subchannel *sch = to_subchannel(dev);
 232
 233         return sprintf(buf, "css:t%01X\n", sch->st);
 234 }
 235
 236 static DEVICE_ATTR(modalias, 0444, modalias_show, NULL);
 237
 238 static struct attribute *subch_attrs[] = {
 239         &dev_attr_type.attr,
 240         &dev_attr_modalias.attr,
 241         NULL,
 242 };
 243
 244 static struct attribute_group subch_attr_group = {
 245         .attrs = subch_attrs,
 246 };
 247
 248 static struct attribute_group *default_subch_attr_groups[] = {
 249         &subch_attr_group,
 250         NULL,
 251 };
 252
 253 static int css_register_subchannel(struct subchannel *sch)
 254 {
 255         int ret;
 256
 257         /* Initialize the subchannel structure */
 258         sch->dev.parent = &channel_subsystems[0]->device;
 259         sch->dev.bus = &css_bus_type;
 260         sch->dev.release = &css_subchannel_release;
 261         sch->dev.groups = default_subch_attr_groups;
 262         /*
 263          * We don't want to generate uevents for I/O subchannels that don't
 264          * have a working ccw device behind them since they will be
 265          * unregistered before they can be used anyway, so we delay the add
 266          * uevent until after device recognition was successful.
 267          * Note that we suppress the uevent for all subchannel types;
 268          * the subchannel driver can decide itself when it wants to inform
 269          * userspace of its existence.
 270          */
 271         sch->dev.uevent_suppress = 1;
 272         css_update_ssd_info(sch);
 273         /* make it known to the system */
 274         ret = css_sch_device_register(sch);
 275         if (ret) {
 276                 CIO_MSG_EVENT(0, "Could not register sch 0.%x.%04x: %d\n",
 277                               sch->schid.ssid, sch->schid.sch_no, ret);
 278                 return ret;
 279         }
 280         if (!sch->driver) {
 281                 /*
 282                  * No driver matched. Generate the uevent now so that
 283                  * a fitting driver module may be loaded based on the
 284                  * modalias.
 285                  */
 286                 sch->dev.uevent_suppress = 0;
 287                 kobject_uevent(&sch->dev.kobj, KOBJ_ADD);
 288         }
 289         return ret;
 290 }
 291
 292 int css_probe_device(struct subchannel_id schid)
 293 {
 294         int ret;
 295         struct subchannel *sch;
 296
 297         sch = css_alloc_subchannel(schid);
 298         if (IS_ERR(sch))
 299                 return PTR_ERR(sch);
 300         ret = css_register_subchannel(sch);
 301         if (ret)
 302                 css_free_subchannel(sch);
 303         return ret;
 304 }
 305
 306 static int
 307 check_subchannel(struct device * dev, void * data)
 308 {
 309         struct subchannel *sch;
 310         struct subchannel_id *schid = data;
 311
 312         sch = to_subchannel(dev);
 313         return schid_equal(&sch->schid, schid);
 314 }
 315
 316 struct subchannel *
 317 get_subchannel_by_schid(struct subchannel_id schid)
 318 {
 319         struct device *dev;
 320
 321         dev = bus_find_device(&css_bus_type, NULL,
 322                               &schid, check_subchannel);
 323
 324         return dev ? to_subchannel(dev) : NULL;
 325 }
 326
 327 /**
 328  * css_sch_is_valid() - check if a subchannel is valid
 329  * @schib: subchannel information block for the subchannel
 330  */
 331 int css_sch_is_valid(struct schib *schib)
 332 {
 333         if ((schib->pmcw.st == SUBCHANNEL_TYPE_IO) && !schib->pmcw.dnv)
 334                 return 0;
 335         if ((schib->pmcw.st == SUBCHANNEL_TYPE_MSG) && !schib->pmcw.w)
 336                 return 0;
 337         return 1;
 338 }
 339 EXPORT_SYMBOL_GPL(css_sch_is_valid);
 340
 341 static int css_evaluate_new_subchannel(struct subchannel_id schid, int slow)
 342 {
 343         struct schib schib;
 344
 345         if (!slow) {
 346                 /* Will be done on the slow path. */
 347                 return -EAGAIN;
 348         }
 349         if (stsch_err(schid, &schib) || !css_sch_is_valid(&schib)) {
 350                 /* Unusable - ignore. */
 351                 return 0;
 352         }
 353         CIO_MSG_EVENT(4, "Evaluating schid 0.%x.%04x, event %d, unknown, "
 354                          "slow path.\n", schid.ssid, schid.sch_no, CIO_OPER);
 355
 356         return css_probe_device(schid);
 357 }
 358
 359 static int css_evaluate_known_subchannel(struct subchannel *sch, int slow)
 360 {
 361         int ret = 0;
 362
 363         if (sch->driver) {
 364                 if (sch->driver->sch_event)
 365                         ret = sch->driver->sch_event(sch, slow);
 366                 else
 367                         dev_dbg(&sch->dev,
 368                                 "Got subchannel machine check but "
 369                                 "no sch_event handler provided.\n");
 370         }
 371         return ret;
 372 }
 373
 374 static void css_evaluate_subchannel(struct subchannel_id schid, int slow)
 375 {
 376         struct subchannel *sch;
 377         int ret;
 378
 379         sch = get_subchannel_by_schid(schid);
 380         if (sch) {
 381                 ret = css_evaluate_known_subchannel(sch, slow);
 382                 put_device(&sch->dev);
 383         } else
 384                 ret = css_evaluate_new_subchannel(schid, slow);
 385         if (ret == -EAGAIN)
 386                 css_schedule_eval(schid);
 387 }
 388
 389 static struct idset *slow_subchannel_set;
 390 static spinlock_t slow_subchannel_lock;
 391
 392 static int __init slow_subchannel_init(void)
 393 {
 394         spin_lock_init(&slow_subchannel_lock);
 395         slow_subchannel_set = idset_sch_new();
 396         if (!slow_subchannel_set) {
 397                 CIO_MSG_EVENT(0, "could not allocate slow subchannel set\n");
 398                 return -ENOMEM;
 399         }
 400         return 0;
 401 }
 402
 403 static int slow_eval_known_fn(struct subchannel *sch, void *data)
 404 {
 405         int eval;
 406         int rc;
 407
 408         spin_lock_irq(&slow_subchannel_lock);
 409         eval = idset_sch_contains(slow_subchannel_set, sch->schid);
 410         idset_sch_del(slow_subchannel_set, sch->schid);
 411         spin_unlock_irq(&slow_subchannel_lock);
 412         if (eval) {
 413                 rc = css_evaluate_known_subchannel(sch, 1);
 414                 if (rc == -EAGAIN)
 415                         css_schedule_eval(sch->schid);
 416         }
 417         return 0;
 418 }
 419
 420 static int slow_eval_unknown_fn(struct subchannel_id schid, void *data)
 421 {
 422         int eval;
 423         int rc = 0;
 424
 425         spin_lock_irq(&slow_subchannel_lock);
 426         eval = idset_sch_contains(slow_subchannel_set, schid);
 427         idset_sch_del(slow_subchannel_set, schid);
 428         spin_unlock_irq(&slow_subchannel_lock);
 429         if (eval) {
 430                 rc = css_evaluate_new_subchannel(schid, 1);
 431                 switch (rc) {
 432                 case -EAGAIN:
 433                         css_schedule_eval(schid);
 434                         rc = 0;
 435                         break;
 436                 case -ENXIO:
 437                 case -ENOMEM:
 438                 case -EIO:
 439                         /* These should abort looping */
 440                         break;
 441                 default:
 442                         rc = 0;
 443                 }
 444         }
 445         return rc;
 446 }
 447
 448 static void css_slow_path_func(struct work_struct *unused)
 449 {
 450         CIO_TRACE_EVENT(4, "slowpath");
 451         for_each_subchannel_staged(slow_eval_known_fn, slow_eval_unknown_fn,
 452                                    NULL);
 453 }
 454
 455 static DECLARE_WORK(slow_path_work, css_slow_path_func);
 456 struct workqueue_struct *slow_path_wq;
 457
 458 void css_schedule_eval(struct subchannel_id schid)
 459 {
 460         unsigned long flags;
 461
 462         spin_lock_irqsave(&slow_subchannel_lock, flags);
 463         idset_sch_add(slow_subchannel_set, schid);
 464         queue_work(slow_path_wq, &slow_path_work);
 465         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 466 }
 467
 468 void css_schedule_eval_all(void)
 469 {
 470         unsigned long flags;
 471
 472         spin_lock_irqsave(&slow_subchannel_lock, flags);
 473         idset_fill(slow_subchannel_set);
 474         queue_work(slow_path_wq, &slow_path_work);
 475         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 476 }
 477
 478 void css_wait_for_slow_path(void)
 479 {
 480         flush_workqueue(slow_path_wq);
 481 }
 482
 483 /* Reprobe subchannel if unregistered. */
 484 static int reprobe_subchannel(struct subchannel_id schid, void *data)
 485 {
 486         int ret;
 487
 488         CIO_MSG_EVENT(6, "cio: reprobe 0.%x.%04x\n",
 489                       schid.ssid, schid.sch_no);
 490         if (need_reprobe)
 491                 return -EAGAIN;
 492
 493         ret = css_probe_device(schid);
 494         switch (ret) {
 495         case 0:
 496                 break;
 497         case -ENXIO:
 498         case -ENOMEM:
 499         case -EIO:
 500                 /* These should abort looping */
 501                 break;
 502         default:
 503                 ret = 0;
 504         }
 505
 506         return ret;
 507 }
 508
 509 /* Work function used to reprobe all unregistered subchannels. */
 510 static void reprobe_all(struct work_struct *unused)
 511 {
 512         int ret;
 513
 514         CIO_MSG_EVENT(4, "reprobe start\n");
 515
 516         need_reprobe = 0;
 517         /* Make sure initial subchannel scan is done. */
 518         wait_event(ccw_device_init_wq,
 519                    atomic_read(&ccw_device_init_count) == 0);
 520         ret = for_each_subchannel_staged(NULL, reprobe_subchannel, NULL);
 521
 522         CIO_MSG_EVENT(4, "reprobe done (rc=%d, need_reprobe=%d)\n", ret,
 523                       need_reprobe);
 524 }
 525
 526 static DECLARE_WORK(css_reprobe_work, reprobe_all);
 527
 528 /* Schedule reprobing of all unregistered subchannels. */
 529 void css_schedule_reprobe(void)
 530 {
 531         need_reprobe = 1;
 532         queue_work(slow_path_wq, &css_reprobe_work);
 533 }
 534
 535 EXPORT_SYMBOL_GPL(css_schedule_reprobe);
 536
 537 /*
 538  * Called from the machine check handler for subchannel report words.
 539  */
 540 static void css_process_crw(struct crw *crw0, struct crw *crw1, int overflow)
 541 {
 542         struct subchannel_id mchk_schid;
 543
 544         if (overflow) {
 545                 css_schedule_eval_all();
 546                 return;
 547         }
 548         CIO_CRW_EVENT(2, "CRW0 reports slct=%d, oflw=%d, "
 549                       "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
 550                       crw0->slct, crw0->oflw, crw0->chn, crw0->rsc, crw0->anc,
 551                       crw0->erc, crw0->rsid);
 552         if (crw1)
 553                 CIO_CRW_EVENT(2, "CRW1 reports slct=%d, oflw=%d, "
 554                               "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
 555                               crw1->slct, crw1->oflw, crw1->chn, crw1->rsc,
 556                               crw1->anc, crw1->erc, crw1->rsid);
 557         init_subchannel_id(&mchk_schid);
 558         mchk_schid.sch_no = crw0->rsid;
 559         if (crw1)
 560                 mchk_schid.ssid = (crw1->rsid >> 8) & 3;
 561
 562         /*
 563          * Since we are always presented with IPI in the CRW, we have to
 564          * use stsch() to find out if the subchannel in question has come
 565          * or gone.
 566          */
 567         css_evaluate_subchannel(mchk_schid, 0);
 568 }
 569
 570 static int __init
 571 __init_channel_subsystem(struct subchannel_id schid, void *data)
 572 {
 573         struct subchannel *sch;
 574         int ret;
 575
 576         if (cio_is_console(schid))
 577                 sch = cio_get_console_subchannel();
 578         else {
 579                 sch = css_alloc_subchannel(schid);
 580                 if (IS_ERR(sch))
 581                         ret = PTR_ERR(sch);
 582                 else
 583                         ret = 0;
 584                 switch (ret) {
 585                 case 0:
 586                         break;
 587                 case -ENOMEM:
 588                         panic("Out of memory in init_channel_subsystem\n");
 589                 /* -ENXIO: no more subchannels. */
 590                 case -ENXIO:
 591                         return ret;
 592                 /* -EIO: this subchannel set not supported. */
 593                 case -EIO:
 594                         return ret;
 595                 default:
 596                         return 0;
 597                 }
 598         }
 599         /*
 600          * We register ALL valid subchannels in ioinfo, even those
 601          * that have been present before init_channel_subsystem.
 602          * These subchannels can't have been registered yet (kmalloc
 603          * not working) so we do it now. This is true e.g. for the
 604          * console subchannel.
 605          */
 606         css_register_subchannel(sch);
 607         return 0;
 608 }
 609
 610 static void __init
 611 css_generate_pgid(struct channel_subsystem *css, u32 tod_high)
 612 {
 613         if (css_general_characteristics.mcss) {
 614                 css->global_pgid.pgid_high.ext_cssid.version = 0x80;
 615                 css->global_pgid.pgid_high.ext_cssid.cssid = css->cssid;
 616         } else {
 617 #ifdef CONFIG_SMP
 618                 css->global_pgid.pgid_high.cpu_addr = hard_smp_processor_id();
 619 #else
 620                 css->global_pgid.pgid_high.cpu_addr = 0;
 621 #endif
 622         }
 623         css->global_pgid.cpu_id = ((cpuid_t *) __LC_CPUID)->ident;
 624         css->global_pgid.cpu_model = ((cpuid_t *) __LC_CPUID)->machine;
 625         css->global_pgid.tod_high = tod_high;
 626
 627 }
 628
 629 static void
 630 channel_subsystem_release(struct device *dev)
 631 {
 632         struct channel_subsystem *css;
 633
 634         css = to_css(dev);
 635         mutex_destroy(&css->mutex);
 636         if (css->pseudo_subchannel) {
 637                 /* Implies that it has been generated but never registered. */
 638                 css_subchannel_release(&css->pseudo_subchannel->dev);
 639                 css->pseudo_subchannel = NULL;
 640         }
 641         kfree(css);
 642 }
 643
 644 static ssize_t
 645 css_cm_enable_show(struct device *dev, struct device_attribute *attr,
 646                    char *buf)
 647 {
 648         struct channel_subsystem *css = to_css(dev);
 649         int ret;
 650
 651         if (!css)
 652                 return 0;
 653         mutex_lock(&css->mutex);
 654         ret = sprintf(buf, "%x\n", css->cm_enabled);
 655         mutex_unlock(&css->mutex);
 656         return ret;
 657 }
 658
 659 static ssize_t
 660 css_cm_enable_store(struct device *dev, struct device_attribute *attr,
 661                     const char *buf, size_t count)
 662 {
 663         struct channel_subsystem *css = to_css(dev);
 664         int ret;
 665         unsigned long val;
 666
 667         ret = strict_strtoul(buf, 16, &val);
 668         if (ret)
 669                 return ret;
 670         mutex_lock(&css->mutex);
 671         switch (val) {
 672         case 0:
 673                 ret = css->cm_enabled ? chsc_secm(css, 0) : 0;
 674                 break;
 675         case 1:
 676                 ret = css->cm_enabled ? 0 : chsc_secm(css, 1);
 677                 break;
 678         default:
 679                 ret = -EINVAL;
 680         }
 681         mutex_unlock(&css->mutex);
 682         return ret < 0 ? ret : count;
 683 }
 684
 685 static DEVICE_ATTR(cm_enable, 0644, css_cm_enable_show, css_cm_enable_store);
 686
 687 static int __init setup_css(int nr)
 688 {
 689         u32 tod_high;
 690         int ret;
 691         struct channel_subsystem *css;
 692
 693         css = channel_subsystems[nr];
 694         memset(css, 0, sizeof(struct channel_subsystem));
 695         css->pseudo_subchannel =
 696                 kzalloc(sizeof(*css->pseudo_subchannel), GFP_KERNEL);
 697         if (!css->pseudo_subchannel)
 698                 return -ENOMEM;
 699         css->pseudo_subchannel->dev.parent = &css->device;
 700         css->pseudo_subchannel->dev.release = css_subchannel_release;
 701         dev_set_name(&css->pseudo_subchannel->dev, "defunct");
 702         ret = cio_create_sch_lock(css->pseudo_subchannel);
 703         if (ret) {
 704                 kfree(css->pseudo_subchannel);
 705                 return ret;
 706         }
 707         mutex_init(&css->mutex);
 708         css->valid = 1;
 709         css->cssid = nr;
 710         dev_set_name(&css->device, "css%x", nr);
 711         css->device.release = channel_subsystem_release;
 712         tod_high = (u32) (get_clock() >> 32);
 713         css_generate_pgid(css, tod_high);
 714         return 0;
 715 }
 716
 717 static int css_reboot_event(struct notifier_block *this,
 718                             unsigned long event,
 719                             void *ptr)
 720 {
 721         int ret, i;
 722
 723         ret = NOTIFY_DONE;
 724         for (i = 0; i <= __MAX_CSSID; i++) {
 725                 struct channel_subsystem *css;
 726
 727                 css = channel_subsystems[i];
 728                 mutex_lock(&css->mutex);
 729                 if (css->cm_enabled)
 730                         if (chsc_secm(css, 0))
 731                                 ret = NOTIFY_BAD;
 732                 mutex_unlock(&css->mutex);
 733         }
 734
 735         return ret;
 736 }
 737
 738 static struct notifier_block css_reboot_notifier = {
 739         .notifier_call = css_reboot_event,
 740 };
 741
 742 /*
 743  * Now that the driver core is running, we can setup our channel subsystem.
 744  * The struct subchannel's are created during probing (except for the
 745  * static console subchannel).
 746  */
 747 static int __init
 748 init_channel_subsystem (void)
 749 {
 750         int ret, i;
 751
 752         ret = chsc_determine_css_characteristics();
 753         if (ret == -ENOMEM)
 754                 goto out; /* No need to continue. */
 755
 756         ret = chsc_alloc_sei_area();
 757         if (ret)
 758                 goto out;
 759
 760         ret = slow_subchannel_init();
 761         if (ret)
 762                 goto out;
 763
 764         ret = s390_register_crw_handler(CRW_RSC_SCH, css_process_crw);
 765         if (ret)
 766                 goto out;
 767
 768         if ((ret = bus_register(&css_bus_type)))
 769                 goto out;
 770
 771         /* Try to enable MSS. */
 772         ret = chsc_enable_facility(CHSC_SDA_OC_MSS);
 773         switch (ret) {
 774         case 0: /* Success. */
 775                 max_ssid = __MAX_SSID;
 776                 break;
 777         case -ENOMEM:
 778                 goto out_bus;
 779         default:
 780                 max_ssid = 0;
 781         }
 782         /* Setup css structure. */
 783         for (i = 0; i <= __MAX_CSSID; i++) {
 784                 struct channel_subsystem *css;
 785
 786                 css = kmalloc(sizeof(struct channel_subsystem), GFP_KERNEL);
 787                 if (!css) {
 788                         ret = -ENOMEM;
 789                         goto out_unregister;
 790                 }
 791                 channel_subsystems[i] = css;
 792                 ret = setup_css(i);
 793                 if (ret) {
 794                         kfree(channel_subsystems[i]);
 795                         goto out_unregister;
 796                 }
 797                 ret = device_register(&css->device);
 798                 if (ret) {
 799                         put_device(&css->device);
 800                         goto out_unregister;
 801                 }
 802                 if (css_chsc_characteristics.secm) {
 803                         ret = device_create_file(&css->device,
 804                                                  &dev_attr_cm_enable);
 805                         if (ret)
 806                                 goto out_device;
 807                 }
 808                 ret = device_register(&css->pseudo_subchannel->dev);
 809                 if (ret)
 810                         goto out_file;
 811         }
 812         ret = register_reboot_notifier(&css_reboot_notifier);
 813         if (ret)
 814                 goto out_unregister;
 815         css_init_done = 1;
 816
 817         /* Enable default isc for I/O subchannels. */
 818         isc_register(IO_SCH_ISC);
 819
 820         for_each_subchannel(__init_channel_subsystem, NULL);
 821         return 0;
 822 out_file:
 823         if (css_chsc_characteristics.secm)
 824                 device_remove_file(&channel_subsystems[i]->device,
 825                                    &dev_attr_cm_enable);
 826 out_device:
 827         device_unregister(&channel_subsystems[i]->device);
 828 out_unregister:
 829         while (i > 0) {
 830                 struct channel_subsystem *css;
 831
 832                 i--;
 833                 css = channel_subsystems[i];
 834                 device_unregister(&css->pseudo_subchannel->dev);
 835                 css->pseudo_subchannel = NULL;
 836                 if (css_chsc_characteristics.secm)
 837                         device_remove_file(&css->device,
 838                                            &dev_attr_cm_enable);
 839                 device_unregister(&css->device);
 840         }
 841 out_bus:
 842         bus_unregister(&css_bus_type);
 843 out:
 844         s390_unregister_crw_handler(CRW_RSC_CSS);
 845         chsc_free_sei_area();
 846         kfree(slow_subchannel_set);
 847         printk(KERN_WARNING"cio: failed to initialize css driver (%d)!\n",
 848                ret);
 849         return ret;
 850 }
 851
 852 int sch_is_pseudo_sch(struct subchannel *sch)
 853 {
 854         return sch == to_css(sch->dev.parent)->pseudo_subchannel;
 855 }
 856
 857 static int css_bus_match(struct device *dev, struct device_driver *drv)
 858 {
 859         struct subchannel *sch = to_subchannel(dev);
 860         struct css_driver *driver = to_cssdriver(drv);
 861         struct css_device_id *id;
 862
 863         for (id = driver->subchannel_type; id->match_flags; id++) {
 864                 if (sch->st == id->type)
 865                         return 1;
 866         }
 867
 868         return 0;
 869 }
 870
 871 static int css_probe(struct device *dev)
 872 {
 873         struct subchannel *sch;
 874         int ret;
 875
 876         sch = to_subchannel(dev);
 877         sch->driver = to_cssdriver(dev->driver);
 878         ret = sch->driver->probe ? sch->driver->probe(sch) : 0;
 879         if (ret)
 880                 sch->driver = NULL;
 881         return ret;
 882 }
 883
 884 static int css_remove(struct device *dev)
 885 {
 886         struct subchannel *sch;
 887         int ret;
 888
 889         sch = to_subchannel(dev);
 890         ret = sch->driver->remove ? sch->driver->remove(sch) : 0;
 891         sch->driver = NULL;
 892         return ret;
 893 }
 894
 895 static void css_shutdown(struct device *dev)
 896 {
 897         struct subchannel *sch;
 898
 899         sch = to_subchannel(dev);
 900         if (sch->driver && sch->driver->shutdown)
 901                 sch->driver->shutdown(sch);
 902 }
 903
 904 static int css_uevent(struct device *dev, struct kobj_uevent_env *env)
 905 {
 906         struct subchannel *sch = to_subchannel(dev);
 907         int ret;
 908
 909         ret = add_uevent_var(env, "ST=%01X", sch->st);
 910         if (ret)
 911                 return ret;
 912         ret = add_uevent_var(env, "MODALIAS=css:t%01X", sch->st);
 913         return ret;
 914 }
 915
 916 struct bus_type css_bus_type = {
 917         .name     = "css",
 918         .match    = css_bus_match,
 919         .probe    = css_probe,
 920         .remove   = css_remove,
 921         .shutdown = css_shutdown,
 922         .uevent   = css_uevent,
 923 };
 924
 925 /**
 926  * css_driver_register - register a css driver
 927  * @cdrv: css driver to register
 928  *
 929  * This is mainly a wrapper around driver_register that sets name
 930  * and bus_type in the embedded struct device_driver correctly.
 931  */
 932 int css_driver_register(struct css_driver *cdrv)
 933 {
 934         cdrv->drv.name = cdrv->name;
 935         cdrv->drv.bus = &css_bus_type;
 936         cdrv->drv.owner = cdrv->owner;
 937         return driver_register(&cdrv->drv);
 938 }
 939 EXPORT_SYMBOL_GPL(css_driver_register);
 940
 941 /**
 942  * css_driver_unregister - unregister a css driver
 943  * @cdrv: css driver to unregister
 944  *
 945  * This is a wrapper around driver_unregister.
 946  */
 947 void css_driver_unregister(struct css_driver *cdrv)
 948 {
 949         driver_unregister(&cdrv->drv);
 950 }
 951 EXPORT_SYMBOL_GPL(css_driver_unregister);
 952
 953 subsys_initcall(init_channel_subsystem);
 954
 955 MODULE_LICENSE("GPL");
 956 EXPORT_SYMBOL(css_bus_type);