drivers/s390/cio/css.c

   1 /*
   2  *  drivers/s390/cio/css.c
   3  *  driver for channel subsystem
   4  *
   5  *    Copyright (C) 2002 IBM Deutschland Entwicklung GmbH,
   6  *                       IBM Corporation
   7  *    Author(s): Arnd Bergmann (arndb@de.ibm.com)
   8  *               Cornelia Huck (cornelia.huck@de.ibm.com)
   9  */
  10 #include <linux/module.h>
  11 #include <linux/init.h>
  12 #include <linux/device.h>
  13 #include <linux/slab.h>
  14 #include <linux/errno.h>
  15 #include <linux/list.h>
  16
  17 #include "css.h"
  18 #include "cio.h"
  19 #include "cio_debug.h"
  20 #include "ioasm.h"
  21 #include "chsc.h"
  22 #include "device.h"
  23
  24 int need_rescan = 0;
  25 int css_init_done = 0;
  26 static int need_reprobe = 0;
  27 static int max_ssid = 0;
  28
  29 struct channel_subsystem *css[__MAX_CSSID + 1];
  30
  31 int css_characteristics_avail = 0;
  32
  33 inline int
  34 for_each_subchannel(int(*fn)(struct subchannel_id, void *), void *data)
  35 {
  36         struct subchannel_id schid;
  37         int ret;
  38
  39         init_subchannel_id(&schid);
  40         ret = -ENODEV;
  41         do {
  42                 do {
  43                         ret = fn(schid, data);
  44                         if (ret)
  45                                 break;
  46                 } while (schid.sch_no++ < __MAX_SUBCHANNEL);
  47                 schid.sch_no = 0;
  48         } while (schid.ssid++ < max_ssid);
  49         return ret;
  50 }
  51
  52 static struct subchannel *
  53 css_alloc_subchannel(struct subchannel_id schid)
  54 {
  55         struct subchannel *sch;
  56         int ret;
  57
  58         sch = kmalloc (sizeof (*sch), GFP_KERNEL | GFP_DMA);
  59         if (sch == NULL)
  60                 return ERR_PTR(-ENOMEM);
  61         ret = cio_validate_subchannel (sch, schid);
  62         if (ret < 0) {
  63                 kfree(sch);
  64                 return ERR_PTR(ret);
  65         }
  66
  67         if (sch->st != SUBCHANNEL_TYPE_IO) {
  68                 /* For now we ignore all non-io subchannels. */
  69                 kfree(sch);
  70                 return ERR_PTR(-EINVAL);
  71         }
  72
  73         /*
  74          * Set intparm to subchannel address.
  75          * This is fine even on 64bit since the subchannel is always located
  76          * under 2G.
  77          */
  78         sch->schib.pmcw.intparm = (__u32)(unsigned long)sch;
  79         ret = cio_modify(sch);
  80         if (ret) {
  81                 kfree(sch);
  82                 return ERR_PTR(ret);
  83         }
  84         return sch;
  85 }
  86
  87 static void
  88 css_free_subchannel(struct subchannel *sch)
  89 {
  90         if (sch) {
  91                 /* Reset intparm to zeroes. */
  92                 sch->schib.pmcw.intparm = 0;
  93                 cio_modify(sch);
  94                 kfree(sch->lock);
  95                 kfree(sch);
  96         }
  97 }
  98
  99 static void
 100 css_subchannel_release(struct device *dev)
 101 {
 102         struct subchannel *sch;
 103
 104         sch = to_subchannel(dev);
 105         if (!cio_is_console(sch->schid)) {
 106                 kfree(sch->lock);
 107                 kfree(sch);
 108         }
 109 }
 110
 111 extern int css_get_ssd_info(struct subchannel *sch);
 112
 113
 114 int css_sch_device_register(struct subchannel *sch)
 115 {
 116         int ret;
 117
 118         mutex_lock(&sch->reg_mutex);
 119         ret = device_register(&sch->dev);
 120         mutex_unlock(&sch->reg_mutex);
 121         return ret;
 122 }
 123
 124 void css_sch_device_unregister(struct subchannel *sch)
 125 {
 126         mutex_lock(&sch->reg_mutex);
 127         device_unregister(&sch->dev);
 128         mutex_unlock(&sch->reg_mutex);
 129 }
 130
 131 static int
 132 css_register_subchannel(struct subchannel *sch)
 133 {
 134         int ret;
 135
 136         /* Initialize the subchannel structure */
 137         sch->dev.parent = &css[0]->device;
 138         sch->dev.bus = &css_bus_type;
 139         sch->dev.release = &css_subchannel_release;
 140         sch->dev.groups = subch_attr_groups;
 141
 142         css_get_ssd_info(sch);
 143
 144         /* make it known to the system */
 145         ret = css_sch_device_register(sch);
 146         if (ret) {
 147                 printk (KERN_WARNING "%s: could not register %s\n",
 148                         __func__, sch->dev.bus_id);
 149                 return ret;
 150         }
 151         return ret;
 152 }
 153
 154 int
 155 css_probe_device(struct subchannel_id schid)
 156 {
 157         int ret;
 158         struct subchannel *sch;
 159
 160         sch = css_alloc_subchannel(schid);
 161         if (IS_ERR(sch))
 162                 return PTR_ERR(sch);
 163         ret = css_register_subchannel(sch);
 164         if (ret)
 165                 css_free_subchannel(sch);
 166         return ret;
 167 }
 168
 169 static int
 170 check_subchannel(struct device * dev, void * data)
 171 {
 172         struct subchannel *sch;
 173         struct subchannel_id *schid = data;
 174
 175         sch = to_subchannel(dev);
 176         return schid_equal(&sch->schid, schid);
 177 }
 178
 179 struct subchannel *
 180 get_subchannel_by_schid(struct subchannel_id schid)
 181 {
 182         struct device *dev;
 183
 184         dev = bus_find_device(&css_bus_type, NULL,
 185                               &schid, check_subchannel);
 186
 187         return dev ? to_subchannel(dev) : NULL;
 188 }
 189
 190 static inline int css_get_subchannel_status(struct subchannel *sch)
 191 {
 192         struct schib schib;
 193
 194         if (stsch(sch->schid, &schib) || !schib.pmcw.dnv)
 195                 return CIO_GONE;
 196         if (sch->schib.pmcw.dnv && (schib.pmcw.dev != sch->schib.pmcw.dev))
 197                 return CIO_REVALIDATE;
 198         if (!sch->lpm)
 199                 return CIO_NO_PATH;
 200         return CIO_OPER;
 201 }
 202
 203 static int css_evaluate_known_subchannel(struct subchannel *sch, int slow)
 204 {
 205         int event, ret, disc;
 206         unsigned long flags;
 207         enum { NONE, UNREGISTER, UNREGISTER_PROBE, REPROBE } action;
 208
 209         spin_lock_irqsave(sch->lock, flags);
 210         disc = device_is_disconnected(sch);
 211         if (disc && slow) {
 212                 /* Disconnected devices are evaluated directly only.*/
 213                 spin_unlock_irqrestore(sch->lock, flags);
 214                 return 0;
 215         }
 216         /* No interrupt after machine check - kill pending timers. */
 217         device_kill_pending_timer(sch);
 218         if (!disc && !slow) {
 219                 /* Non-disconnected devices are evaluated on the slow path. */
 220                 spin_unlock_irqrestore(sch->lock, flags);
 221                 return -EAGAIN;
 222         }
 223         event = css_get_subchannel_status(sch);
 224         CIO_MSG_EVENT(4, "Evaluating schid 0.%x.%04x, event %d, %s, %s path.\n",
 225                       sch->schid.ssid, sch->schid.sch_no, event,
 226                       disc ? "disconnected" : "normal",
 227                       slow ? "slow" : "fast");
 228         /* Analyze subchannel status. */
 229         action = NONE;
 230         switch (event) {
 231         case CIO_NO_PATH:
 232                 if (disc) {
 233                         /* Check if paths have become available. */
 234                         action = REPROBE;
 235                         break;
 236                 }
 237                 /* fall through */
 238         case CIO_GONE:
 239                 /* Prevent unwanted effects when opening lock. */
 240                 cio_disable_subchannel(sch);
 241                 device_set_disconnected(sch);
 242                 /* Ask driver what to do with device. */
 243                 action = UNREGISTER;
 244                 if (sch->driver && sch->driver->notify) {
 245                         spin_unlock_irqrestore(sch->lock, flags);
 246                         ret = sch->driver->notify(&sch->dev, event);
 247                         spin_lock_irqsave(sch->lock, flags);
 248                         if (ret)
 249                                 action = NONE;
 250                 }
 251                 break;
 252         case CIO_REVALIDATE:
 253                 /* Device will be removed, so no notify necessary. */
 254                 if (disc)
 255                         /* Reprobe because immediate unregister might block. */
 256                         action = REPROBE;
 257                 else
 258                         action = UNREGISTER_PROBE;
 259                 break;
 260         case CIO_OPER:
 261                 if (disc)
 262                         /* Get device operational again. */
 263                         action = REPROBE;
 264                 break;
 265         }
 266         /* Perform action. */
 267         ret = 0;
 268         switch (action) {
 269         case UNREGISTER:
 270         case UNREGISTER_PROBE:
 271                 /* Unregister device (will use subchannel lock). */
 272                 spin_unlock_irqrestore(sch->lock, flags);
 273                 css_sch_device_unregister(sch);
 274                 spin_lock_irqsave(sch->lock, flags);
 275
 276                 /* Reset intparm to zeroes. */
 277                 sch->schib.pmcw.intparm = 0;
 278                 cio_modify(sch);
 279                 break;
 280         case REPROBE:
 281                 device_trigger_reprobe(sch);
 282                 break;
 283         default:
 284                 break;
 285         }
 286         spin_unlock_irqrestore(sch->lock, flags);
 287         /* Probe if necessary. */
 288         if (action == UNREGISTER_PROBE)
 289                 ret = css_probe_device(sch->schid);
 290
 291         return ret;
 292 }
 293
 294 static int css_evaluate_new_subchannel(struct subchannel_id schid, int slow)
 295 {
 296         struct schib schib;
 297
 298         if (!slow) {
 299                 /* Will be done on the slow path. */
 300                 return -EAGAIN;
 301         }
 302         if (stsch(schid, &schib) || !schib.pmcw.dnv) {
 303                 /* Unusable - ignore. */
 304                 return 0;
 305         }
 306         CIO_MSG_EVENT(4, "Evaluating schid 0.%x.%04x, event %d, unknown, "
 307                          "slow path.\n", schid.ssid, schid.sch_no, CIO_OPER);
 308
 309         return css_probe_device(schid);
 310 }
 311
 312 static int css_evaluate_subchannel(struct subchannel_id schid, int slow)
 313 {
 314         struct subchannel *sch;
 315         int ret;
 316
 317         sch = get_subchannel_by_schid(schid);
 318         if (sch) {
 319                 ret = css_evaluate_known_subchannel(sch, slow);
 320                 put_device(&sch->dev);
 321         } else
 322                 ret = css_evaluate_new_subchannel(schid, slow);
 323
 324         return ret;
 325 }
 326
 327 static int
 328 css_rescan_devices(struct subchannel_id schid, void *data)
 329 {
 330         return css_evaluate_subchannel(schid, 1);
 331 }
 332
 333 struct slow_subchannel {
 334         struct list_head slow_list;
 335         struct subchannel_id schid;
 336 };
 337
 338 static LIST_HEAD(slow_subchannels_head);
 339 static DEFINE_SPINLOCK(slow_subchannel_lock);
 340
 341 static void
 342 css_trigger_slow_path(struct work_struct *unused)
 343 {
 344         CIO_TRACE_EVENT(4, "slowpath");
 345
 346         if (need_rescan) {
 347                 need_rescan = 0;
 348                 for_each_subchannel(css_rescan_devices, NULL);
 349                 return;
 350         }
 351
 352         spin_lock_irq(&slow_subchannel_lock);
 353         while (!list_empty(&slow_subchannels_head)) {
 354                 struct slow_subchannel *slow_sch =
 355                         list_entry(slow_subchannels_head.next,
 356                                    struct slow_subchannel, slow_list);
 357
 358                 list_del_init(slow_subchannels_head.next);
 359                 spin_unlock_irq(&slow_subchannel_lock);
 360                 css_evaluate_subchannel(slow_sch->schid, 1);
 361                 spin_lock_irq(&slow_subchannel_lock);
 362                 kfree(slow_sch);
 363         }
 364         spin_unlock_irq(&slow_subchannel_lock);
 365 }
 366
 367 DECLARE_WORK(slow_path_work, css_trigger_slow_path);
 368 struct workqueue_struct *slow_path_wq;
 369
 370 /* Reprobe subchannel if unregistered. */
 371 static int reprobe_subchannel(struct subchannel_id schid, void *data)
 372 {
 373         struct subchannel *sch;
 374         int ret;
 375
 376         CIO_DEBUG(KERN_INFO, 6, "cio: reprobe 0.%x.%04x\n",
 377                   schid.ssid, schid.sch_no);
 378         if (need_reprobe)
 379                 return -EAGAIN;
 380
 381         sch = get_subchannel_by_schid(schid);
 382         if (sch) {
 383                 /* Already known. */
 384                 put_device(&sch->dev);
 385                 return 0;
 386         }
 387
 388         ret = css_probe_device(schid);
 389         switch (ret) {
 390         case 0:
 391                 break;
 392         case -ENXIO:
 393         case -ENOMEM:
 394                 /* These should abort looping */
 395                 break;
 396         default:
 397                 ret = 0;
 398         }
 399
 400         return ret;
 401 }
 402
 403 /* Work function used to reprobe all unregistered subchannels. */
 404 static void reprobe_all(struct work_struct *unused)
 405 {
 406         int ret;
 407
 408         CIO_MSG_EVENT(2, "reprobe start\n");
 409
 410         need_reprobe = 0;
 411         /* Make sure initial subchannel scan is done. */
 412         wait_event(ccw_device_init_wq,
 413                    atomic_read(&ccw_device_init_count) == 0);
 414         ret = for_each_subchannel(reprobe_subchannel, NULL);
 415
 416         CIO_MSG_EVENT(2, "reprobe done (rc=%d, need_reprobe=%d)\n", ret,
 417                       need_reprobe);
 418 }
 419
 420 DECLARE_WORK(css_reprobe_work, reprobe_all);
 421
 422 /* Schedule reprobing of all unregistered subchannels. */
 423 void css_schedule_reprobe(void)
 424 {
 425         need_reprobe = 1;
 426         queue_work(ccw_device_work, &css_reprobe_work);
 427 }
 428
 429 EXPORT_SYMBOL_GPL(css_schedule_reprobe);
 430
 431 /*
 432  * Rescan for new devices. FIXME: This is slow.
 433  * This function is called when we have lost CRWs due to overflows and we have
 434  * to do subchannel housekeeping.
 435  */
 436 void
 437 css_reiterate_subchannels(void)
 438 {
 439         css_clear_subchannel_slow_list();
 440         need_rescan = 1;
 441 }
 442
 443 /*
 444  * Called from the machine check handler for subchannel report words.
 445  */
 446 int
 447 css_process_crw(int rsid1, int rsid2)
 448 {
 449         int ret;
 450         struct subchannel_id mchk_schid;
 451
 452         CIO_CRW_EVENT(2, "source is subchannel %04X, subsystem id %x\n",
 453                       rsid1, rsid2);
 454
 455         if (need_rescan)
 456                 /* We need to iterate all subchannels anyway. */
 457                 return -EAGAIN;
 458
 459         init_subchannel_id(&mchk_schid);
 460         mchk_schid.sch_no = rsid1;
 461         if (rsid2 != 0)
 462                 mchk_schid.ssid = (rsid2 >> 8) & 3;
 463
 464         /*
 465          * Since we are always presented with IPI in the CRW, we have to
 466          * use stsch() to find out if the subchannel in question has come
 467          * or gone.
 468          */
 469         ret = css_evaluate_subchannel(mchk_schid, 0);
 470         if (ret == -EAGAIN) {
 471                 if (css_enqueue_subchannel_slow(mchk_schid)) {
 472                         css_clear_subchannel_slow_list();
 473                         need_rescan = 1;
 474                 }
 475         }
 476         return ret;
 477 }
 478
 479 static int __init
 480 __init_channel_subsystem(struct subchannel_id schid, void *data)
 481 {
 482         struct subchannel *sch;
 483         int ret;
 484
 485         if (cio_is_console(schid))
 486                 sch = cio_get_console_subchannel();
 487         else {
 488                 sch = css_alloc_subchannel(schid);
 489                 if (IS_ERR(sch))
 490                         ret = PTR_ERR(sch);
 491                 else
 492                         ret = 0;
 493                 switch (ret) {
 494                 case 0:
 495                         break;
 496                 case -ENOMEM:
 497                         panic("Out of memory in init_channel_subsystem\n");
 498                 /* -ENXIO: no more subchannels. */
 499                 case -ENXIO:
 500                         return ret;
 501                 /* -EIO: this subchannel set not supported. */
 502                 case -EIO:
 503                         return ret;
 504                 default:
 505                         return 0;
 506                 }
 507         }
 508         /*
 509          * We register ALL valid subchannels in ioinfo, even those
 510          * that have been present before init_channel_subsystem.
 511          * These subchannels can't have been registered yet (kmalloc
 512          * not working) so we do it now. This is true e.g. for the
 513          * console subchannel.
 514          */
 515         css_register_subchannel(sch);
 516         return 0;
 517 }
 518
 519 static void __init
 520 css_generate_pgid(struct channel_subsystem *css, u32 tod_high)
 521 {
 522         if (css_characteristics_avail && css_general_characteristics.mcss) {
 523                 css->global_pgid.pgid_high.ext_cssid.version = 0x80;
 524                 css->global_pgid.pgid_high.ext_cssid.cssid = css->cssid;
 525         } else {
 526 #ifdef CONFIG_SMP
 527                 css->global_pgid.pgid_high.cpu_addr = hard_smp_processor_id();
 528 #else
 529                 css->global_pgid.pgid_high.cpu_addr = 0;
 530 #endif
 531         }
 532         css->global_pgid.cpu_id = ((cpuid_t *) __LC_CPUID)->ident;
 533         css->global_pgid.cpu_model = ((cpuid_t *) __LC_CPUID)->machine;
 534         css->global_pgid.tod_high = tod_high;
 535
 536 }
 537
 538 static void
 539 channel_subsystem_release(struct device *dev)
 540 {
 541         struct channel_subsystem *css;
 542
 543         css = to_css(dev);
 544         mutex_destroy(&css->mutex);
 545         kfree(css);
 546 }
 547
 548 static ssize_t
 549 css_cm_enable_show(struct device *dev, struct device_attribute *attr,
 550                    char *buf)
 551 {
 552         struct channel_subsystem *css = to_css(dev);
 553
 554         if (!css)
 555                 return 0;
 556         return sprintf(buf, "%x\n", css->cm_enabled);
 557 }
 558
 559 static ssize_t
 560 css_cm_enable_store(struct device *dev, struct device_attribute *attr,
 561                     const char *buf, size_t count)
 562 {
 563         struct channel_subsystem *css = to_css(dev);
 564         int ret;
 565
 566         switch (buf[0]) {
 567         case '0':
 568                 ret = css->cm_enabled ? chsc_secm(css, 0) : 0;
 569                 break;
 570         case '1':
 571                 ret = css->cm_enabled ? 0 : chsc_secm(css, 1);
 572                 break;
 573         default:
 574                 ret = -EINVAL;
 575         }
 576         return ret < 0 ? ret : count;
 577 }
 578
 579 static DEVICE_ATTR(cm_enable, 0644, css_cm_enable_show, css_cm_enable_store);
 580
 581 static inline int __init setup_css(int nr)
 582 {
 583         u32 tod_high;
 584         int ret;
 585
 586         memset(css[nr], 0, sizeof(struct channel_subsystem));
 587         css[nr]->pseudo_subchannel =
 588                 kzalloc(sizeof(*css[nr]->pseudo_subchannel), GFP_KERNEL);
 589         if (!css[nr]->pseudo_subchannel)
 590                 return -ENOMEM;
 591         css[nr]->pseudo_subchannel->dev.parent = &css[nr]->device;
 592         css[nr]->pseudo_subchannel->dev.release = css_subchannel_release;
 593         sprintf(css[nr]->pseudo_subchannel->dev.bus_id, "defunct");
 594         ret = cio_create_sch_lock(css[nr]->pseudo_subchannel);
 595         if (ret) {
 596                 kfree(css[nr]->pseudo_subchannel);
 597                 return ret;
 598         }
 599         mutex_init(&css[nr]->mutex);
 600         css[nr]->valid = 1;
 601         css[nr]->cssid = nr;
 602         sprintf(css[nr]->device.bus_id, "css%x", nr);
 603         css[nr]->device.release = channel_subsystem_release;
 604         tod_high = (u32) (get_clock() >> 32);
 605         css_generate_pgid(css[nr], tod_high);
 606         return 0;
 607 }
 608
 609 /*
 610  * Now that the driver core is running, we can setup our channel subsystem.
 611  * The struct subchannel's are created during probing (except for the
 612  * static console subchannel).
 613  */
 614 static int __init
 615 init_channel_subsystem (void)
 616 {
 617         int ret, i;
 618
 619         if (chsc_determine_css_characteristics() == 0)
 620                 css_characteristics_avail = 1;
 621
 622         if ((ret = bus_register(&css_bus_type)))
 623                 goto out;
 624
 625         /* Try to enable MSS. */
 626         ret = chsc_enable_facility(CHSC_SDA_OC_MSS);
 627         switch (ret) {
 628         case 0: /* Success. */
 629                 max_ssid = __MAX_SSID;
 630                 break;
 631         case -ENOMEM:
 632                 goto out_bus;
 633         default:
 634                 max_ssid = 0;
 635         }
 636         /* Setup css structure. */
 637         for (i = 0; i <= __MAX_CSSID; i++) {
 638                 css[i] = kmalloc(sizeof(struct channel_subsystem), GFP_KERNEL);
 639                 if (!css[i]) {
 640                         ret = -ENOMEM;
 641                         goto out_unregister;
 642                 }
 643                 ret = setup_css(i);
 644                 if (ret)
 645                         goto out_free;
 646                 ret = device_register(&css[i]->device);
 647                 if (ret)
 648                         goto out_free_all;
 649                 if (css_characteristics_avail &&
 650                     css_chsc_characteristics.secm) {
 651                         ret = device_create_file(&css[i]->device,
 652                                                  &dev_attr_cm_enable);
 653                         if (ret)
 654                                 goto out_device;
 655                 }
 656                 ret = device_register(&css[i]->pseudo_subchannel->dev);
 657                 if (ret)
 658                         goto out_file;
 659         }
 660         css_init_done = 1;
 661
 662         ctl_set_bit(6, 28);
 663
 664         for_each_subchannel(__init_channel_subsystem, NULL);
 665         return 0;
 666 out_file:
 667         device_remove_file(&css[i]->device, &dev_attr_cm_enable);
 668 out_device:
 669         device_unregister(&css[i]->device);
 670 out_free_all:
 671         kfree(css[i]->pseudo_subchannel->lock);
 672         kfree(css[i]->pseudo_subchannel);
 673 out_free:
 674         kfree(css[i]);
 675 out_unregister:
 676         while (i > 0) {
 677                 i--;
 678                 device_unregister(&css[i]->pseudo_subchannel->dev);
 679                 if (css_characteristics_avail && css_chsc_characteristics.secm)
 680                         device_remove_file(&css[i]->device,
 681                                            &dev_attr_cm_enable);
 682                 device_unregister(&css[i]->device);
 683         }
 684 out_bus:
 685         bus_unregister(&css_bus_type);
 686 out:
 687         return ret;
 688 }
 689
 690 int sch_is_pseudo_sch(struct subchannel *sch)
 691 {
 692         return sch == to_css(sch->dev.parent)->pseudo_subchannel;
 693 }
 694
 695 /*
 696  * find a driver for a subchannel. They identify by the subchannel
 697  * type with the exception that the console subchannel driver has its own
 698  * subchannel type although the device is an i/o subchannel
 699  */
 700 static int
 701 css_bus_match (struct device *dev, struct device_driver *drv)
 702 {
 703         struct subchannel *sch = container_of (dev, struct subchannel, dev);
 704         struct css_driver *driver = container_of (drv, struct css_driver, drv);
 705
 706         if (sch->st == driver->subchannel_type)
 707                 return 1;
 708
 709         return 0;
 710 }
 711
 712 static int
 713 css_probe (struct device *dev)
 714 {
 715         struct subchannel *sch;
 716
 717         sch = to_subchannel(dev);
 718         sch->driver = container_of (dev->driver, struct css_driver, drv);
 719         return (sch->driver->probe ? sch->driver->probe(sch) : 0);
 720 }
 721
 722 static int
 723 css_remove (struct device *dev)
 724 {
 725         struct subchannel *sch;
 726
 727         sch = to_subchannel(dev);
 728         return (sch->driver->remove ? sch->driver->remove(sch) : 0);
 729 }
 730
 731 static void
 732 css_shutdown (struct device *dev)
 733 {
 734         struct subchannel *sch;
 735
 736         sch = to_subchannel(dev);
 737         if (sch->driver->shutdown)
 738                 sch->driver->shutdown(sch);
 739 }
 740
 741 struct bus_type css_bus_type = {
 742         .name     = "css",
 743         .match    = css_bus_match,
 744         .probe    = css_probe,
 745         .remove   = css_remove,
 746         .shutdown = css_shutdown,
 747 };
 748
 749 subsys_initcall(init_channel_subsystem);
 750
 751 int
 752 css_enqueue_subchannel_slow(struct subchannel_id schid)
 753 {
 754         struct slow_subchannel *new_slow_sch;
 755         unsigned long flags;
 756
 757         new_slow_sch = kzalloc(sizeof(struct slow_subchannel), GFP_ATOMIC);
 758         if (!new_slow_sch)
 759                 return -ENOMEM;
 760         new_slow_sch->schid = schid;
 761         spin_lock_irqsave(&slow_subchannel_lock, flags);
 762         list_add_tail(&new_slow_sch->slow_list, &slow_subchannels_head);
 763         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 764         return 0;
 765 }
 766
 767 void
 768 css_clear_subchannel_slow_list(void)
 769 {
 770         unsigned long flags;
 771
 772         spin_lock_irqsave(&slow_subchannel_lock, flags);
 773         while (!list_empty(&slow_subchannels_head)) {
 774                 struct slow_subchannel *slow_sch =
 775                         list_entry(slow_subchannels_head.next,
 776                                    struct slow_subchannel, slow_list);
 777
 778                 list_del_init(slow_subchannels_head.next);
 779                 kfree(slow_sch);
 780         }
 781         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 782 }
 783
 784
 785
 786 int
 787 css_slow_subchannels_exist(void)
 788 {
 789         return (!list_empty(&slow_subchannels_head));
 790 }
 791
 792 MODULE_LICENSE("GPL");
 793 EXPORT_SYMBOL(css_bus_type);
 794 EXPORT_SYMBOL_GPL(css_characteristics_avail);