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 #include "idset.h"
  24 #include "chp.h"
  25
  26 int css_init_done = 0;
  27 static int need_reprobe = 0;
  28 static int max_ssid = 0;
  29
  30 struct channel_subsystem *css[__MAX_CSSID + 1];
  31
  32 int css_characteristics_avail = 0;
  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 static struct subchannel *
  54 css_alloc_subchannel(struct subchannel_id schid)
  55 {
  56         struct subchannel *sch;
  57         int ret;
  58
  59         sch = kmalloc (sizeof (*sch), GFP_KERNEL | GFP_DMA);
  60         if (sch == NULL)
  61                 return ERR_PTR(-ENOMEM);
  62         ret = cio_validate_subchannel (sch, schid);
  63         if (ret < 0) {
  64                 kfree(sch);
  65                 return ERR_PTR(ret);
  66         }
  67
  68         if (sch->st != SUBCHANNEL_TYPE_IO) {
  69                 /* For now we ignore all non-io subchannels. */
  70                 kfree(sch);
  71                 return ERR_PTR(-EINVAL);
  72         }
  73
  74         /*
  75          * Set intparm to subchannel address.
  76          * This is fine even on 64bit since the subchannel is always located
  77          * under 2G.
  78          */
  79         sch->schib.pmcw.intparm = (__u32)(unsigned long)sch;
  80         ret = cio_modify(sch);
  81         if (ret) {
  82                 kfree(sch);
  83                 return ERR_PTR(ret);
  84         }
  85         return sch;
  86 }
  87
  88 static void
  89 css_free_subchannel(struct subchannel *sch)
  90 {
  91         if (sch) {
  92                 /* Reset intparm to zeroes. */
  93                 sch->schib.pmcw.intparm = 0;
  94                 cio_modify(sch);
  95                 kfree(sch->lock);
  96                 kfree(sch);
  97         }
  98 }
  99
 100 static void
 101 css_subchannel_release(struct device *dev)
 102 {
 103         struct subchannel *sch;
 104
 105         sch = to_subchannel(dev);
 106         if (!cio_is_console(sch->schid)) {
 107                 kfree(sch->lock);
 108                 kfree(sch);
 109         }
 110 }
 111
 112 static int css_sch_device_register(struct subchannel *sch)
 113 {
 114         int ret;
 115
 116         mutex_lock(&sch->reg_mutex);
 117         ret = device_register(&sch->dev);
 118         mutex_unlock(&sch->reg_mutex);
 119         return ret;
 120 }
 121
 122 void css_sch_device_unregister(struct subchannel *sch)
 123 {
 124         mutex_lock(&sch->reg_mutex);
 125         device_unregister(&sch->dev);
 126         mutex_unlock(&sch->reg_mutex);
 127 }
 128
 129 static void ssd_from_pmcw(struct chsc_ssd_info *ssd, struct pmcw *pmcw)
 130 {
 131         int i;
 132         int mask;
 133
 134         memset(ssd, 0, sizeof(struct chsc_ssd_info));
 135         ssd->path_mask = pmcw->pim;
 136         for (i = 0; i < 8; i++) {
 137                 mask = 0x80 >> i;
 138                 if (pmcw->pim & mask) {
 139                         chp_id_init(&ssd->chpid[i]);
 140                         ssd->chpid[i].id = pmcw->chpid[i];
 141                 }
 142         }
 143 }
 144
 145 static void ssd_register_chpids(struct chsc_ssd_info *ssd)
 146 {
 147         int i;
 148         int mask;
 149
 150         for (i = 0; i < 8; i++) {
 151                 mask = 0x80 >> i;
 152                 if (ssd->path_mask & mask)
 153                         if (!chp_is_registered(ssd->chpid[i]))
 154                                 chp_new(ssd->chpid[i]);
 155         }
 156 }
 157
 158 void css_update_ssd_info(struct subchannel *sch)
 159 {
 160         int ret;
 161
 162         if (cio_is_console(sch->schid)) {
 163                 /* Console is initialized too early for functions requiring
 164                  * memory allocation. */
 165                 ssd_from_pmcw(&sch->ssd_info, &sch->schib.pmcw);
 166         } else {
 167                 ret = chsc_get_ssd_info(sch->schid, &sch->ssd_info);
 168                 if (ret)
 169                         ssd_from_pmcw(&sch->ssd_info, &sch->schib.pmcw);
 170                 ssd_register_chpids(&sch->ssd_info);
 171         }
 172 }
 173
 174 static int css_register_subchannel(struct subchannel *sch)
 175 {
 176         int ret;
 177
 178         /* Initialize the subchannel structure */
 179         sch->dev.parent = &css[0]->device;
 180         sch->dev.bus = &css_bus_type;
 181         sch->dev.release = &css_subchannel_release;
 182         sch->dev.groups = subch_attr_groups;
 183         css_update_ssd_info(sch);
 184         /* make it known to the system */
 185         ret = css_sch_device_register(sch);
 186         if (ret) {
 187                 CIO_MSG_EVENT(0, "Could not register sch 0.%x.%04x: %d\n",
 188                               sch->schid.ssid, sch->schid.sch_no, ret);
 189                 return ret;
 190         }
 191         return ret;
 192 }
 193
 194 static int css_probe_device(struct subchannel_id schid)
 195 {
 196         int ret;
 197         struct subchannel *sch;
 198
 199         sch = css_alloc_subchannel(schid);
 200         if (IS_ERR(sch))
 201                 return PTR_ERR(sch);
 202         ret = css_register_subchannel(sch);
 203         if (ret)
 204                 css_free_subchannel(sch);
 205         return ret;
 206 }
 207
 208 static int
 209 check_subchannel(struct device * dev, void * data)
 210 {
 211         struct subchannel *sch;
 212         struct subchannel_id *schid = data;
 213
 214         sch = to_subchannel(dev);
 215         return schid_equal(&sch->schid, schid);
 216 }
 217
 218 struct subchannel *
 219 get_subchannel_by_schid(struct subchannel_id schid)
 220 {
 221         struct device *dev;
 222
 223         dev = bus_find_device(&css_bus_type, NULL,
 224                               &schid, check_subchannel);
 225
 226         return dev ? to_subchannel(dev) : NULL;
 227 }
 228
 229 static int css_get_subchannel_status(struct subchannel *sch)
 230 {
 231         struct schib schib;
 232
 233         if (stsch(sch->schid, &schib) || !schib.pmcw.dnv)
 234                 return CIO_GONE;
 235         if (sch->schib.pmcw.dnv && (schib.pmcw.dev != sch->schib.pmcw.dev))
 236                 return CIO_REVALIDATE;
 237         if (!sch->lpm)
 238                 return CIO_NO_PATH;
 239         return CIO_OPER;
 240 }
 241
 242 static int css_evaluate_known_subchannel(struct subchannel *sch, int slow)
 243 {
 244         int event, ret, disc;
 245         unsigned long flags;
 246         enum { NONE, UNREGISTER, UNREGISTER_PROBE, REPROBE } action;
 247
 248         spin_lock_irqsave(sch->lock, flags);
 249         disc = device_is_disconnected(sch);
 250         if (disc && slow) {
 251                 /* Disconnected devices are evaluated directly only.*/
 252                 spin_unlock_irqrestore(sch->lock, flags);
 253                 return 0;
 254         }
 255         /* No interrupt after machine check - kill pending timers. */
 256         device_kill_pending_timer(sch);
 257         if (!disc && !slow) {
 258                 /* Non-disconnected devices are evaluated on the slow path. */
 259                 spin_unlock_irqrestore(sch->lock, flags);
 260                 return -EAGAIN;
 261         }
 262         event = css_get_subchannel_status(sch);
 263         CIO_MSG_EVENT(4, "Evaluating schid 0.%x.%04x, event %d, %s, %s path.\n",
 264                       sch->schid.ssid, sch->schid.sch_no, event,
 265                       disc ? "disconnected" : "normal",
 266                       slow ? "slow" : "fast");
 267         /* Analyze subchannel status. */
 268         action = NONE;
 269         switch (event) {
 270         case CIO_NO_PATH:
 271                 if (disc) {
 272                         /* Check if paths have become available. */
 273                         action = REPROBE;
 274                         break;
 275                 }
 276                 /* fall through */
 277         case CIO_GONE:
 278                 /* Prevent unwanted effects when opening lock. */
 279                 cio_disable_subchannel(sch);
 280                 device_set_disconnected(sch);
 281                 /* Ask driver what to do with device. */
 282                 action = UNREGISTER;
 283                 if (sch->driver && sch->driver->notify) {
 284                         spin_unlock_irqrestore(sch->lock, flags);
 285                         ret = sch->driver->notify(&sch->dev, event);
 286                         spin_lock_irqsave(sch->lock, flags);
 287                         if (ret)
 288                                 action = NONE;
 289                 }
 290                 break;
 291         case CIO_REVALIDATE:
 292                 /* Device will be removed, so no notify necessary. */
 293                 if (disc)
 294                         /* Reprobe because immediate unregister might block. */
 295                         action = REPROBE;
 296                 else
 297                         action = UNREGISTER_PROBE;
 298                 break;
 299         case CIO_OPER:
 300                 if (disc)
 301                         /* Get device operational again. */
 302                         action = REPROBE;
 303                 break;
 304         }
 305         /* Perform action. */
 306         ret = 0;
 307         switch (action) {
 308         case UNREGISTER:
 309         case UNREGISTER_PROBE:
 310                 /* Unregister device (will use subchannel lock). */
 311                 spin_unlock_irqrestore(sch->lock, flags);
 312                 css_sch_device_unregister(sch);
 313                 spin_lock_irqsave(sch->lock, flags);
 314
 315                 /* Reset intparm to zeroes. */
 316                 sch->schib.pmcw.intparm = 0;
 317                 cio_modify(sch);
 318                 break;
 319         case REPROBE:
 320                 device_trigger_reprobe(sch);
 321                 break;
 322         default:
 323                 break;
 324         }
 325         spin_unlock_irqrestore(sch->lock, flags);
 326         /* Probe if necessary. */
 327         if (action == UNREGISTER_PROBE)
 328                 ret = css_probe_device(sch->schid);
 329
 330         return ret;
 331 }
 332
 333 static int css_evaluate_new_subchannel(struct subchannel_id schid, int slow)
 334 {
 335         struct schib schib;
 336
 337         if (!slow) {
 338                 /* Will be done on the slow path. */
 339                 return -EAGAIN;
 340         }
 341         if (stsch_err(schid, &schib) || !schib.pmcw.dnv) {
 342                 /* Unusable - ignore. */
 343                 return 0;
 344         }
 345         CIO_MSG_EVENT(4, "Evaluating schid 0.%x.%04x, event %d, unknown, "
 346                          "slow path.\n", schid.ssid, schid.sch_no, CIO_OPER);
 347
 348         return css_probe_device(schid);
 349 }
 350
 351 static void css_evaluate_subchannel(struct subchannel_id schid, int slow)
 352 {
 353         struct subchannel *sch;
 354         int ret;
 355
 356         sch = get_subchannel_by_schid(schid);
 357         if (sch) {
 358                 ret = css_evaluate_known_subchannel(sch, slow);
 359                 put_device(&sch->dev);
 360         } else
 361                 ret = css_evaluate_new_subchannel(schid, slow);
 362         if (ret == -EAGAIN)
 363                 css_schedule_eval(schid);
 364 }
 365
 366 static struct idset *slow_subchannel_set;
 367 static spinlock_t slow_subchannel_lock;
 368
 369 static int __init slow_subchannel_init(void)
 370 {
 371         spin_lock_init(&slow_subchannel_lock);
 372         slow_subchannel_set = idset_sch_new();
 373         if (!slow_subchannel_set) {
 374                 CIO_MSG_EVENT(0, "could not allocate slow subchannel set\n");
 375                 return -ENOMEM;
 376         }
 377         return 0;
 378 }
 379
 380 subsys_initcall(slow_subchannel_init);
 381
 382 static void css_slow_path_func(struct work_struct *unused)
 383 {
 384         struct subchannel_id schid;
 385
 386         CIO_TRACE_EVENT(4, "slowpath");
 387         spin_lock_irq(&slow_subchannel_lock);
 388         init_subchannel_id(&schid);
 389         while (idset_sch_get_first(slow_subchannel_set, &schid)) {
 390                 idset_sch_del(slow_subchannel_set, schid);
 391                 spin_unlock_irq(&slow_subchannel_lock);
 392                 css_evaluate_subchannel(schid, 1);
 393                 spin_lock_irq(&slow_subchannel_lock);
 394         }
 395         spin_unlock_irq(&slow_subchannel_lock);
 396 }
 397
 398 static DECLARE_WORK(slow_path_work, css_slow_path_func);
 399 struct workqueue_struct *slow_path_wq;
 400
 401 void css_schedule_eval(struct subchannel_id schid)
 402 {
 403         unsigned long flags;
 404
 405         spin_lock_irqsave(&slow_subchannel_lock, flags);
 406         idset_sch_add(slow_subchannel_set, schid);
 407         queue_work(slow_path_wq, &slow_path_work);
 408         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 409 }
 410
 411 void css_schedule_eval_all(void)
 412 {
 413         unsigned long flags;
 414
 415         spin_lock_irqsave(&slow_subchannel_lock, flags);
 416         idset_fill(slow_subchannel_set);
 417         queue_work(slow_path_wq, &slow_path_work);
 418         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 419 }
 420
 421 /* Reprobe subchannel if unregistered. */
 422 static int reprobe_subchannel(struct subchannel_id schid, void *data)
 423 {
 424         struct subchannel *sch;
 425         int ret;
 426
 427         CIO_MSG_EVENT(6, "cio: reprobe 0.%x.%04x\n",
 428                       schid.ssid, schid.sch_no);
 429         if (need_reprobe)
 430                 return -EAGAIN;
 431
 432         sch = get_subchannel_by_schid(schid);
 433         if (sch) {
 434                 /* Already known. */
 435                 put_device(&sch->dev);
 436                 return 0;
 437         }
 438
 439         ret = css_probe_device(schid);
 440         switch (ret) {
 441         case 0:
 442                 break;
 443         case -ENXIO:
 444         case -ENOMEM:
 445                 /* These should abort looping */
 446                 break;
 447         default:
 448                 ret = 0;
 449         }
 450
 451         return ret;
 452 }
 453
 454 /* Work function used to reprobe all unregistered subchannels. */
 455 static void reprobe_all(struct work_struct *unused)
 456 {
 457         int ret;
 458
 459         CIO_MSG_EVENT(2, "reprobe start\n");
 460
 461         need_reprobe = 0;
 462         /* Make sure initial subchannel scan is done. */
 463         wait_event(ccw_device_init_wq,
 464                    atomic_read(&ccw_device_init_count) == 0);
 465         ret = for_each_subchannel(reprobe_subchannel, NULL);
 466
 467         CIO_MSG_EVENT(2, "reprobe done (rc=%d, need_reprobe=%d)\n", ret,
 468                       need_reprobe);
 469 }
 470
 471 static DECLARE_WORK(css_reprobe_work, reprobe_all);
 472
 473 /* Schedule reprobing of all unregistered subchannels. */
 474 void css_schedule_reprobe(void)
 475 {
 476         need_reprobe = 1;
 477         queue_work(ccw_device_work, &css_reprobe_work);
 478 }
 479
 480 EXPORT_SYMBOL_GPL(css_schedule_reprobe);
 481
 482 /*
 483  * Called from the machine check handler for subchannel report words.
 484  */
 485 void css_process_crw(int rsid1, int rsid2)
 486 {
 487         struct subchannel_id mchk_schid;
 488
 489         CIO_CRW_EVENT(2, "source is subchannel %04X, subsystem id %x\n",
 490                       rsid1, rsid2);
 491         init_subchannel_id(&mchk_schid);
 492         mchk_schid.sch_no = rsid1;
 493         if (rsid2 != 0)
 494                 mchk_schid.ssid = (rsid2 >> 8) & 3;
 495
 496         /*
 497          * Since we are always presented with IPI in the CRW, we have to
 498          * use stsch() to find out if the subchannel in question has come
 499          * or gone.
 500          */
 501         css_evaluate_subchannel(mchk_schid, 0);
 502 }
 503
 504 static int __init
 505 __init_channel_subsystem(struct subchannel_id schid, void *data)
 506 {
 507         struct subchannel *sch;
 508         int ret;
 509
 510         if (cio_is_console(schid))
 511                 sch = cio_get_console_subchannel();
 512         else {
 513                 sch = css_alloc_subchannel(schid);
 514                 if (IS_ERR(sch))
 515                         ret = PTR_ERR(sch);
 516                 else
 517                         ret = 0;
 518                 switch (ret) {
 519                 case 0:
 520                         break;
 521                 case -ENOMEM:
 522                         panic("Out of memory in init_channel_subsystem\n");
 523                 /* -ENXIO: no more subchannels. */
 524                 case -ENXIO:
 525                         return ret;
 526                 /* -EIO: this subchannel set not supported. */
 527                 case -EIO:
 528                         return ret;
 529                 default:
 530                         return 0;
 531                 }
 532         }
 533         /*
 534          * We register ALL valid subchannels in ioinfo, even those
 535          * that have been present before init_channel_subsystem.
 536          * These subchannels can't have been registered yet (kmalloc
 537          * not working) so we do it now. This is true e.g. for the
 538          * console subchannel.
 539          */
 540         css_register_subchannel(sch);
 541         return 0;
 542 }
 543
 544 static void __init
 545 css_generate_pgid(struct channel_subsystem *css, u32 tod_high)
 546 {
 547         if (css_characteristics_avail && css_general_characteristics.mcss) {
 548                 css->global_pgid.pgid_high.ext_cssid.version = 0x80;
 549                 css->global_pgid.pgid_high.ext_cssid.cssid = css->cssid;
 550         } else {
 551 #ifdef CONFIG_SMP
 552                 css->global_pgid.pgid_high.cpu_addr = hard_smp_processor_id();
 553 #else
 554                 css->global_pgid.pgid_high.cpu_addr = 0;
 555 #endif
 556         }
 557         css->global_pgid.cpu_id = ((cpuid_t *) __LC_CPUID)->ident;
 558         css->global_pgid.cpu_model = ((cpuid_t *) __LC_CPUID)->machine;
 559         css->global_pgid.tod_high = tod_high;
 560
 561 }
 562
 563 static void
 564 channel_subsystem_release(struct device *dev)
 565 {
 566         struct channel_subsystem *css;
 567
 568         css = to_css(dev);
 569         mutex_destroy(&css->mutex);
 570         kfree(css);
 571 }
 572
 573 static ssize_t
 574 css_cm_enable_show(struct device *dev, struct device_attribute *attr,
 575                    char *buf)
 576 {
 577         struct channel_subsystem *css = to_css(dev);
 578
 579         if (!css)
 580                 return 0;
 581         return sprintf(buf, "%x\n", css->cm_enabled);
 582 }
 583
 584 static ssize_t
 585 css_cm_enable_store(struct device *dev, struct device_attribute *attr,
 586                     const char *buf, size_t count)
 587 {
 588         struct channel_subsystem *css = to_css(dev);
 589         int ret;
 590
 591         switch (buf[0]) {
 592         case '0':
 593                 ret = css->cm_enabled ? chsc_secm(css, 0) : 0;
 594                 break;
 595         case '1':
 596                 ret = css->cm_enabled ? 0 : chsc_secm(css, 1);
 597                 break;
 598         default:
 599                 ret = -EINVAL;
 600         }
 601         return ret < 0 ? ret : count;
 602 }
 603
 604 static DEVICE_ATTR(cm_enable, 0644, css_cm_enable_show, css_cm_enable_store);
 605
 606 static int __init setup_css(int nr)
 607 {
 608         u32 tod_high;
 609         int ret;
 610
 611         memset(css[nr], 0, sizeof(struct channel_subsystem));
 612         css[nr]->pseudo_subchannel =
 613                 kzalloc(sizeof(*css[nr]->pseudo_subchannel), GFP_KERNEL);
 614         if (!css[nr]->pseudo_subchannel)
 615                 return -ENOMEM;
 616         css[nr]->pseudo_subchannel->dev.parent = &css[nr]->device;
 617         css[nr]->pseudo_subchannel->dev.release = css_subchannel_release;
 618         sprintf(css[nr]->pseudo_subchannel->dev.bus_id, "defunct");
 619         ret = cio_create_sch_lock(css[nr]->pseudo_subchannel);
 620         if (ret) {
 621                 kfree(css[nr]->pseudo_subchannel);
 622                 return ret;
 623         }
 624         mutex_init(&css[nr]->mutex);
 625         css[nr]->valid = 1;
 626         css[nr]->cssid = nr;
 627         sprintf(css[nr]->device.bus_id, "css%x", nr);
 628         css[nr]->device.release = channel_subsystem_release;
 629         tod_high = (u32) (get_clock() >> 32);
 630         css_generate_pgid(css[nr], tod_high);
 631         return 0;
 632 }
 633
 634 /*
 635  * Now that the driver core is running, we can setup our channel subsystem.
 636  * The struct subchannel's are created during probing (except for the
 637  * static console subchannel).
 638  */
 639 static int __init
 640 init_channel_subsystem (void)
 641 {
 642         int ret, i;
 643
 644         if (chsc_determine_css_characteristics() == 0)
 645                 css_characteristics_avail = 1;
 646
 647         if ((ret = bus_register(&css_bus_type)))
 648                 goto out;
 649
 650         /* Try to enable MSS. */
 651         ret = chsc_enable_facility(CHSC_SDA_OC_MSS);
 652         switch (ret) {
 653         case 0: /* Success. */
 654                 max_ssid = __MAX_SSID;
 655                 break;
 656         case -ENOMEM:
 657                 goto out_bus;
 658         default:
 659                 max_ssid = 0;
 660         }
 661         /* Setup css structure. */
 662         for (i = 0; i <= __MAX_CSSID; i++) {
 663                 css[i] = kmalloc(sizeof(struct channel_subsystem), GFP_KERNEL);
 664                 if (!css[i]) {
 665                         ret = -ENOMEM;
 666                         goto out_unregister;
 667                 }
 668                 ret = setup_css(i);
 669                 if (ret)
 670                         goto out_free;
 671                 ret = device_register(&css[i]->device);
 672                 if (ret)
 673                         goto out_free_all;
 674                 if (css_characteristics_avail &&
 675                     css_chsc_characteristics.secm) {
 676                         ret = device_create_file(&css[i]->device,
 677                                                  &dev_attr_cm_enable);
 678                         if (ret)
 679                                 goto out_device;
 680                 }
 681                 ret = device_register(&css[i]->pseudo_subchannel->dev);
 682                 if (ret)
 683                         goto out_file;
 684         }
 685         css_init_done = 1;
 686
 687         ctl_set_bit(6, 28);
 688
 689         for_each_subchannel(__init_channel_subsystem, NULL);
 690         return 0;
 691 out_file:
 692         device_remove_file(&css[i]->device, &dev_attr_cm_enable);
 693 out_device:
 694         device_unregister(&css[i]->device);
 695 out_free_all:
 696         kfree(css[i]->pseudo_subchannel->lock);
 697         kfree(css[i]->pseudo_subchannel);
 698 out_free:
 699         kfree(css[i]);
 700 out_unregister:
 701         while (i > 0) {
 702                 i--;
 703                 device_unregister(&css[i]->pseudo_subchannel->dev);
 704                 if (css_characteristics_avail && css_chsc_characteristics.secm)
 705                         device_remove_file(&css[i]->device,
 706                                            &dev_attr_cm_enable);
 707                 device_unregister(&css[i]->device);
 708         }
 709 out_bus:
 710         bus_unregister(&css_bus_type);
 711 out:
 712         return ret;
 713 }
 714
 715 int sch_is_pseudo_sch(struct subchannel *sch)
 716 {
 717         return sch == to_css(sch->dev.parent)->pseudo_subchannel;
 718 }
 719
 720 /*
 721  * find a driver for a subchannel. They identify by the subchannel
 722  * type with the exception that the console subchannel driver has its own
 723  * subchannel type although the device is an i/o subchannel
 724  */
 725 static int
 726 css_bus_match (struct device *dev, struct device_driver *drv)
 727 {
 728         struct subchannel *sch = container_of (dev, struct subchannel, dev);
 729         struct css_driver *driver = container_of (drv, struct css_driver, drv);
 730
 731         if (sch->st == driver->subchannel_type)
 732                 return 1;
 733
 734         return 0;
 735 }
 736
 737 static int
 738 css_probe (struct device *dev)
 739 {
 740         struct subchannel *sch;
 741
 742         sch = to_subchannel(dev);
 743         sch->driver = container_of (dev->driver, struct css_driver, drv);
 744         return (sch->driver->probe ? sch->driver->probe(sch) : 0);
 745 }
 746
 747 static int
 748 css_remove (struct device *dev)
 749 {
 750         struct subchannel *sch;
 751
 752         sch = to_subchannel(dev);
 753         return (sch->driver->remove ? sch->driver->remove(sch) : 0);
 754 }
 755
 756 static void
 757 css_shutdown (struct device *dev)
 758 {
 759         struct subchannel *sch;
 760
 761         sch = to_subchannel(dev);
 762         if (sch->driver->shutdown)
 763                 sch->driver->shutdown(sch);
 764 }
 765
 766 struct bus_type css_bus_type = {
 767         .name     = "css",
 768         .match    = css_bus_match,
 769         .probe    = css_probe,
 770         .remove   = css_remove,
 771         .shutdown = css_shutdown,
 772 };
 773
 774 subsys_initcall(init_channel_subsystem);
 775
 776 MODULE_LICENSE("GPL");
 777 EXPORT_SYMBOL(css_bus_type);
 778 EXPORT_SYMBOL_GPL(css_characteristics_avail);