drivers/s390/cio/css.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * driver for channel subsystem
   4  *
   5  * Copyright IBM Corp. 2002, 2010
   6  *
   7  * Author(s): Arnd Bergmann (arndb@de.ibm.com)
   8  *            Cornelia Huck (cornelia.huck@de.ibm.com)
   9  */
  10
  11 #define KMSG_COMPONENT "cio"
  12 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  13
  14 #include <linux/export.h>
  15 #include <linux/init.h>
  16 #include <linux/device.h>
  17 #include <linux/slab.h>
  18 #include <linux/errno.h>
  19 #include <linux/list.h>
  20 #include <linux/reboot.h>
  21 #include <linux/proc_fs.h>
  22 #include <linux/genalloc.h>
  23 #include <linux/dma-mapping.h>
  24 #include <asm/isc.h>
  25 #include <asm/crw.h>
  26
  27 #include "css.h"
  28 #include "cio.h"
  29 #include "blacklist.h"
  30 #include "cio_debug.h"
  31 #include "ioasm.h"
  32 #include "chsc.h"
  33 #include "device.h"
  34 #include "idset.h"
  35 #include "chp.h"
  36
  37 int css_init_done = 0;
  38 int max_ssid;
  39
  40 #define MAX_CSS_IDX 0
  41 struct channel_subsystem *channel_subsystems[MAX_CSS_IDX + 1];
  42 static struct bus_type css_bus_type;
  43
  44 int
  45 for_each_subchannel(int(*fn)(struct subchannel_id, void *), void *data)
  46 {
  47         struct subchannel_id schid;
  48         int ret;
  49
  50         init_subchannel_id(&schid);
  51         do {
  52                 do {
  53                         ret = fn(schid, data);
  54                         if (ret)
  55                                 break;
  56                 } while (schid.sch_no++ < __MAX_SUBCHANNEL);
  57                 schid.sch_no = 0;
  58         } while (schid.ssid++ < max_ssid);
  59         return ret;
  60 }
  61
  62 struct cb_data {
  63         void *data;
  64         struct idset *set;
  65         int (*fn_known_sch)(struct subchannel *, void *);
  66         int (*fn_unknown_sch)(struct subchannel_id, void *);
  67 };
  68
  69 static int call_fn_known_sch(struct device *dev, void *data)
  70 {
  71         struct subchannel *sch = to_subchannel(dev);
  72         struct cb_data *cb = data;
  73         int rc = 0;
  74
  75         if (cb->set)
  76                 idset_sch_del(cb->set, sch->schid);
  77         if (cb->fn_known_sch)
  78                 rc = cb->fn_known_sch(sch, cb->data);
  79         return rc;
  80 }
  81
  82 static int call_fn_unknown_sch(struct subchannel_id schid, void *data)
  83 {
  84         struct cb_data *cb = data;
  85         int rc = 0;
  86
  87         if (idset_sch_contains(cb->set, schid))
  88                 rc = cb->fn_unknown_sch(schid, cb->data);
  89         return rc;
  90 }
  91
  92 static int call_fn_all_sch(struct subchannel_id schid, void *data)
  93 {
  94         struct cb_data *cb = data;
  95         struct subchannel *sch;
  96         int rc = 0;
  97
  98         sch = get_subchannel_by_schid(schid);
  99         if (sch) {
 100                 if (cb->fn_known_sch)
 101                         rc = cb->fn_known_sch(sch, cb->data);
 102                 put_device(&sch->dev);
 103         } else {
 104                 if (cb->fn_unknown_sch)
 105                         rc = cb->fn_unknown_sch(schid, cb->data);
 106         }
 107
 108         return rc;
 109 }
 110
 111 int for_each_subchannel_staged(int (*fn_known)(struct subchannel *, void *),
 112                                int (*fn_unknown)(struct subchannel_id,
 113                                void *), void *data)
 114 {
 115         struct cb_data cb;
 116         int rc;
 117
 118         cb.data = data;
 119         cb.fn_known_sch = fn_known;
 120         cb.fn_unknown_sch = fn_unknown;
 121
 122         if (fn_known && !fn_unknown) {
 123                 /* Skip idset allocation in case of known-only loop. */
 124                 cb.set = NULL;
 125                 return bus_for_each_dev(&css_bus_type, NULL, &cb,
 126                                         call_fn_known_sch);
 127         }
 128
 129         cb.set = idset_sch_new();
 130         if (!cb.set)
 131                 /* fall back to brute force scanning in case of oom */
 132                 return for_each_subchannel(call_fn_all_sch, &cb);
 133
 134         idset_fill(cb.set);
 135
 136         /* Process registered subchannels. */
 137         rc = bus_for_each_dev(&css_bus_type, NULL, &cb, call_fn_known_sch);
 138         if (rc)
 139                 goto out;
 140         /* Process unregistered subchannels. */
 141         if (fn_unknown)
 142                 rc = for_each_subchannel(call_fn_unknown_sch, &cb);
 143 out:
 144         idset_free(cb.set);
 145
 146         return rc;
 147 }
 148
 149 static void css_sch_todo(struct work_struct *work);
 150
 151 static int css_sch_create_locks(struct subchannel *sch)
 152 {
 153         sch->lock = kmalloc(sizeof(*sch->lock), GFP_KERNEL);
 154         if (!sch->lock)
 155                 return -ENOMEM;
 156
 157         spin_lock_init(sch->lock);
 158         mutex_init(&sch->reg_mutex);
 159
 160         return 0;
 161 }
 162
 163 static void css_subchannel_release(struct device *dev)
 164 {
 165         struct subchannel *sch = to_subchannel(dev);
 166
 167         sch->config.intparm = 0;
 168         cio_commit_config(sch);
 169         kfree(sch->driver_override);
 170         kfree(sch->lock);
 171         kfree(sch);
 172 }
 173
 174 static int css_validate_subchannel(struct subchannel_id schid,
 175                                    struct schib *schib)
 176 {
 177         int err;
 178
 179         switch (schib->pmcw.st) {
 180         case SUBCHANNEL_TYPE_IO:
 181         case SUBCHANNEL_TYPE_MSG:
 182                 if (!css_sch_is_valid(schib))
 183                         err = -ENODEV;
 184                 else if (is_blacklisted(schid.ssid, schib->pmcw.dev)) {
 185                         CIO_MSG_EVENT(6, "Blacklisted device detected "
 186                                       "at devno %04X, subchannel set %x\n",
 187                                       schib->pmcw.dev, schid.ssid);
 188                         err = -ENODEV;
 189                 } else
 190                         err = 0;
 191                 break;
 192         default:
 193                 err = 0;
 194         }
 195         if (err)
 196                 goto out;
 197
 198         CIO_MSG_EVENT(4, "Subchannel 0.%x.%04x reports subchannel type %04X\n",
 199                       schid.ssid, schid.sch_no, schib->pmcw.st);
 200 out:
 201         return err;
 202 }
 203
 204 struct subchannel *css_alloc_subchannel(struct subchannel_id schid,
 205                                         struct schib *schib)
 206 {
 207         struct subchannel *sch;
 208         int ret;
 209
 210         ret = css_validate_subchannel(schid, schib);
 211         if (ret < 0)
 212                 return ERR_PTR(ret);
 213
 214         sch = kzalloc(sizeof(*sch), GFP_KERNEL | GFP_DMA);
 215         if (!sch)
 216                 return ERR_PTR(-ENOMEM);
 217
 218         sch->schid = schid;
 219         sch->schib = *schib;
 220         sch->st = schib->pmcw.st;
 221
 222         ret = css_sch_create_locks(sch);
 223         if (ret)
 224                 goto err;
 225
 226         INIT_WORK(&sch->todo_work, css_sch_todo);
 227         sch->dev.release = &css_subchannel_release;
 228         sch->dev.dma_mask = &sch->dma_mask;
 229         device_initialize(&sch->dev);
 230         /*
 231          * The physical addresses for some of the dma structures that can
 232          * belong to a subchannel need to fit 31 bit width (e.g. ccw).
 233          */
 234         ret = dma_set_coherent_mask(&sch->dev, DMA_BIT_MASK(31));
 235         if (ret)
 236                 goto err;
 237         /*
 238          * But we don't have such restrictions imposed on the stuff that
 239          * is handled by the streaming API.
 240          */
 241         ret = dma_set_mask(&sch->dev, DMA_BIT_MASK(64));
 242         if (ret)
 243                 goto err;
 244
 245         return sch;
 246
 247 err:
 248         kfree(sch);
 249         return ERR_PTR(ret);
 250 }
 251
 252 static int css_sch_device_register(struct subchannel *sch)
 253 {
 254         int ret;
 255
 256         mutex_lock(&sch->reg_mutex);
 257         dev_set_name(&sch->dev, "0.%x.%04x", sch->schid.ssid,
 258                      sch->schid.sch_no);
 259         ret = device_add(&sch->dev);
 260         mutex_unlock(&sch->reg_mutex);
 261         return ret;
 262 }
 263
 264 /**
 265  * css_sch_device_unregister - unregister a subchannel
 266  * @sch: subchannel to be unregistered
 267  */
 268 void css_sch_device_unregister(struct subchannel *sch)
 269 {
 270         mutex_lock(&sch->reg_mutex);
 271         if (device_is_registered(&sch->dev))
 272                 device_unregister(&sch->dev);
 273         mutex_unlock(&sch->reg_mutex);
 274 }
 275 EXPORT_SYMBOL_GPL(css_sch_device_unregister);
 276
 277 static void ssd_from_pmcw(struct chsc_ssd_info *ssd, struct pmcw *pmcw)
 278 {
 279         int i;
 280         int mask;
 281
 282         memset(ssd, 0, sizeof(struct chsc_ssd_info));
 283         ssd->path_mask = pmcw->pim;
 284         for (i = 0; i < 8; i++) {
 285                 mask = 0x80 >> i;
 286                 if (pmcw->pim & mask) {
 287                         chp_id_init(&ssd->chpid[i]);
 288                         ssd->chpid[i].id = pmcw->chpid[i];
 289                 }
 290         }
 291 }
 292
 293 static void ssd_register_chpids(struct chsc_ssd_info *ssd)
 294 {
 295         int i;
 296         int mask;
 297
 298         for (i = 0; i < 8; i++) {
 299                 mask = 0x80 >> i;
 300                 if (ssd->path_mask & mask)
 301                         chp_new(ssd->chpid[i]);
 302         }
 303 }
 304
 305 void css_update_ssd_info(struct subchannel *sch)
 306 {
 307         int ret;
 308
 309         ret = chsc_get_ssd_info(sch->schid, &sch->ssd_info);
 310         if (ret)
 311                 ssd_from_pmcw(&sch->ssd_info, &sch->schib.pmcw);
 312
 313         ssd_register_chpids(&sch->ssd_info);
 314 }
 315
 316 static ssize_t type_show(struct device *dev, struct device_attribute *attr,
 317                          char *buf)
 318 {
 319         struct subchannel *sch = to_subchannel(dev);
 320
 321         return sprintf(buf, "%01x\n", sch->st);
 322 }
 323
 324 static DEVICE_ATTR_RO(type);
 325
 326 static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
 327                              char *buf)
 328 {
 329         struct subchannel *sch = to_subchannel(dev);
 330
 331         return sprintf(buf, "css:t%01X\n", sch->st);
 332 }
 333
 334 static DEVICE_ATTR_RO(modalias);
 335
 336 static ssize_t driver_override_store(struct device *dev,
 337                                      struct device_attribute *attr,
 338                                      const char *buf, size_t count)
 339 {
 340         struct subchannel *sch = to_subchannel(dev);
 341         char *driver_override, *old, *cp;
 342
 343         /* We need to keep extra room for a newline */
 344         if (count >= (PAGE_SIZE - 1))
 345                 return -EINVAL;
 346
 347         driver_override = kstrndup(buf, count, GFP_KERNEL);
 348         if (!driver_override)
 349                 return -ENOMEM;
 350
 351         cp = strchr(driver_override, '\n');
 352         if (cp)
 353                 *cp = '\0';
 354
 355         device_lock(dev);
 356         old = sch->driver_override;
 357         if (strlen(driver_override)) {
 358                 sch->driver_override = driver_override;
 359         } else {
 360                 kfree(driver_override);
 361                 sch->driver_override = NULL;
 362         }
 363         device_unlock(dev);
 364
 365         kfree(old);
 366
 367         return count;
 368 }
 369
 370 static ssize_t driver_override_show(struct device *dev,
 371                                     struct device_attribute *attr, char *buf)
 372 {
 373         struct subchannel *sch = to_subchannel(dev);
 374         ssize_t len;
 375
 376         device_lock(dev);
 377         len = snprintf(buf, PAGE_SIZE, "%s\n", sch->driver_override);
 378         device_unlock(dev);
 379         return len;
 380 }
 381 static DEVICE_ATTR_RW(driver_override);
 382
 383 static struct attribute *subch_attrs[] = {
 384         &dev_attr_type.attr,
 385         &dev_attr_modalias.attr,
 386         &dev_attr_driver_override.attr,
 387         NULL,
 388 };
 389
 390 static struct attribute_group subch_attr_group = {
 391         .attrs = subch_attrs,
 392 };
 393
 394 static const struct attribute_group *default_subch_attr_groups[] = {
 395         &subch_attr_group,
 396         NULL,
 397 };
 398
 399 static ssize_t chpids_show(struct device *dev,
 400                            struct device_attribute *attr,
 401                            char *buf)
 402 {
 403         struct subchannel *sch = to_subchannel(dev);
 404         struct chsc_ssd_info *ssd = &sch->ssd_info;
 405         ssize_t ret = 0;
 406         int mask;
 407         int chp;
 408
 409         for (chp = 0; chp < 8; chp++) {
 410                 mask = 0x80 >> chp;
 411                 if (ssd->path_mask & mask)
 412                         ret += sprintf(buf + ret, "%02x ", ssd->chpid[chp].id);
 413                 else
 414                         ret += sprintf(buf + ret, "00 ");
 415         }
 416         ret += sprintf(buf + ret, "\n");
 417         return ret;
 418 }
 419 static DEVICE_ATTR_RO(chpids);
 420
 421 static ssize_t pimpampom_show(struct device *dev,
 422                               struct device_attribute *attr,
 423                               char *buf)
 424 {
 425         struct subchannel *sch = to_subchannel(dev);
 426         struct pmcw *pmcw = &sch->schib.pmcw;
 427
 428         return sprintf(buf, "%02x %02x %02x\n",
 429                        pmcw->pim, pmcw->pam, pmcw->pom);
 430 }
 431 static DEVICE_ATTR_RO(pimpampom);
 432
 433 static ssize_t dev_busid_show(struct device *dev,
 434                               struct device_attribute *attr,
 435                               char *buf)
 436 {
 437         struct subchannel *sch = to_subchannel(dev);
 438         struct pmcw *pmcw = &sch->schib.pmcw;
 439
 440         if ((pmcw->st == SUBCHANNEL_TYPE_IO ||
 441              pmcw->st == SUBCHANNEL_TYPE_MSG) && pmcw->dnv)
 442                 return sysfs_emit(buf, "0.%x.%04x\n", sch->schid.ssid,
 443                                   pmcw->dev);
 444         else
 445                 return sysfs_emit(buf, "none\n");
 446 }
 447 static DEVICE_ATTR_RO(dev_busid);
 448
 449 static struct attribute *io_subchannel_type_attrs[] = {
 450         &dev_attr_chpids.attr,
 451         &dev_attr_pimpampom.attr,
 452         &dev_attr_dev_busid.attr,
 453         NULL,
 454 };
 455 ATTRIBUTE_GROUPS(io_subchannel_type);
 456
 457 static const struct device_type io_subchannel_type = {
 458         .groups = io_subchannel_type_groups,
 459 };
 460
 461 int css_register_subchannel(struct subchannel *sch)
 462 {
 463         int ret;
 464
 465         /* Initialize the subchannel structure */
 466         sch->dev.parent = &channel_subsystems[0]->device;
 467         sch->dev.bus = &css_bus_type;
 468         sch->dev.groups = default_subch_attr_groups;
 469
 470         if (sch->st == SUBCHANNEL_TYPE_IO)
 471                 sch->dev.type = &io_subchannel_type;
 472
 473         /*
 474          * We don't want to generate uevents for I/O subchannels that don't
 475          * have a working ccw device behind them since they will be
 476          * unregistered before they can be used anyway, so we delay the add
 477          * uevent until after device recognition was successful.
 478          * Note that we suppress the uevent for all subchannel types;
 479          * the subchannel driver can decide itself when it wants to inform
 480          * userspace of its existence.
 481          */
 482         dev_set_uevent_suppress(&sch->dev, 1);
 483         css_update_ssd_info(sch);
 484         /* make it known to the system */
 485         ret = css_sch_device_register(sch);
 486         if (ret) {
 487                 CIO_MSG_EVENT(0, "Could not register sch 0.%x.%04x: %d\n",
 488                               sch->schid.ssid, sch->schid.sch_no, ret);
 489                 return ret;
 490         }
 491         if (!sch->driver) {
 492                 /*
 493                  * No driver matched. Generate the uevent now so that
 494                  * a fitting driver module may be loaded based on the
 495                  * modalias.
 496                  */
 497                 dev_set_uevent_suppress(&sch->dev, 0);
 498                 kobject_uevent(&sch->dev.kobj, KOBJ_ADD);
 499         }
 500         return ret;
 501 }
 502
 503 static int css_probe_device(struct subchannel_id schid, struct schib *schib)
 504 {
 505         struct subchannel *sch;
 506         int ret;
 507
 508         sch = css_alloc_subchannel(schid, schib);
 509         if (IS_ERR(sch))
 510                 return PTR_ERR(sch);
 511
 512         ret = css_register_subchannel(sch);
 513         if (ret)
 514                 put_device(&sch->dev);
 515
 516         return ret;
 517 }
 518
 519 static int
 520 check_subchannel(struct device *dev, const void *data)
 521 {
 522         struct subchannel *sch;
 523         struct subchannel_id *schid = (void *)data;
 524
 525         sch = to_subchannel(dev);
 526         return schid_equal(&sch->schid, schid);
 527 }
 528
 529 struct subchannel *
 530 get_subchannel_by_schid(struct subchannel_id schid)
 531 {
 532         struct device *dev;
 533
 534         dev = bus_find_device(&css_bus_type, NULL,
 535                               &schid, check_subchannel);
 536
 537         return dev ? to_subchannel(dev) : NULL;
 538 }
 539
 540 /**
 541  * css_sch_is_valid() - check if a subchannel is valid
 542  * @schib: subchannel information block for the subchannel
 543  */
 544 int css_sch_is_valid(struct schib *schib)
 545 {
 546         if ((schib->pmcw.st == SUBCHANNEL_TYPE_IO) && !schib->pmcw.dnv)
 547                 return 0;
 548         if ((schib->pmcw.st == SUBCHANNEL_TYPE_MSG) && !schib->pmcw.w)
 549                 return 0;
 550         return 1;
 551 }
 552 EXPORT_SYMBOL_GPL(css_sch_is_valid);
 553
 554 static int css_evaluate_new_subchannel(struct subchannel_id schid, int slow)
 555 {
 556         struct schib schib;
 557         int ccode;
 558
 559         if (!slow) {
 560                 /* Will be done on the slow path. */
 561                 return -EAGAIN;
 562         }
 563         /*
 564          * The first subchannel that is not-operational (ccode==3)
 565          * indicates that there aren't any more devices available.
 566          * If stsch gets an exception, it means the current subchannel set
 567          * is not valid.
 568          */
 569         ccode = stsch(schid, &schib);
 570         if (ccode)
 571                 return (ccode == 3) ? -ENXIO : ccode;
 572
 573         return css_probe_device(schid, &schib);
 574 }
 575
 576 static int css_evaluate_known_subchannel(struct subchannel *sch, int slow)
 577 {
 578         int ret = 0;
 579
 580         if (sch->driver) {
 581                 if (sch->driver->sch_event)
 582                         ret = sch->driver->sch_event(sch, slow);
 583                 else
 584                         dev_dbg(&sch->dev,
 585                                 "Got subchannel machine check but "
 586                                 "no sch_event handler provided.\n");
 587         }
 588         if (ret != 0 && ret != -EAGAIN) {
 589                 CIO_MSG_EVENT(2, "eval: sch 0.%x.%04x, rc=%d\n",
 590                               sch->schid.ssid, sch->schid.sch_no, ret);
 591         }
 592         return ret;
 593 }
 594
 595 static void css_evaluate_subchannel(struct subchannel_id schid, int slow)
 596 {
 597         struct subchannel *sch;
 598         int ret;
 599
 600         sch = get_subchannel_by_schid(schid);
 601         if (sch) {
 602                 ret = css_evaluate_known_subchannel(sch, slow);
 603                 put_device(&sch->dev);
 604         } else
 605                 ret = css_evaluate_new_subchannel(schid, slow);
 606         if (ret == -EAGAIN)
 607                 css_schedule_eval(schid);
 608 }
 609
 610 /**
 611  * css_sched_sch_todo - schedule a subchannel operation
 612  * @sch: subchannel
 613  * @todo: todo
 614  *
 615  * Schedule the operation identified by @todo to be performed on the slow path
 616  * workqueue. Do nothing if another operation with higher priority is already
 617  * scheduled. Needs to be called with subchannel lock held.
 618  */
 619 void css_sched_sch_todo(struct subchannel *sch, enum sch_todo todo)
 620 {
 621         CIO_MSG_EVENT(4, "sch_todo: sched sch=0.%x.%04x todo=%d\n",
 622                       sch->schid.ssid, sch->schid.sch_no, todo);
 623         if (sch->todo >= todo)
 624                 return;
 625         /* Get workqueue ref. */
 626         if (!get_device(&sch->dev))
 627                 return;
 628         sch->todo = todo;
 629         if (!queue_work(cio_work_q, &sch->todo_work)) {
 630                 /* Already queued, release workqueue ref. */
 631                 put_device(&sch->dev);
 632         }
 633 }
 634 EXPORT_SYMBOL_GPL(css_sched_sch_todo);
 635
 636 static void css_sch_todo(struct work_struct *work)
 637 {
 638         struct subchannel *sch;
 639         enum sch_todo todo;
 640         int ret;
 641
 642         sch = container_of(work, struct subchannel, todo_work);
 643         /* Find out todo. */
 644         spin_lock_irq(sch->lock);
 645         todo = sch->todo;
 646         CIO_MSG_EVENT(4, "sch_todo: sch=0.%x.%04x, todo=%d\n", sch->schid.ssid,
 647                       sch->schid.sch_no, todo);
 648         sch->todo = SCH_TODO_NOTHING;
 649         spin_unlock_irq(sch->lock);
 650         /* Perform todo. */
 651         switch (todo) {
 652         case SCH_TODO_NOTHING:
 653                 break;
 654         case SCH_TODO_EVAL:
 655                 ret = css_evaluate_known_subchannel(sch, 1);
 656                 if (ret == -EAGAIN) {
 657                         spin_lock_irq(sch->lock);
 658                         css_sched_sch_todo(sch, todo);
 659                         spin_unlock_irq(sch->lock);
 660                 }
 661                 break;
 662         case SCH_TODO_UNREG:
 663                 css_sch_device_unregister(sch);
 664                 break;
 665         }
 666         /* Release workqueue ref. */
 667         put_device(&sch->dev);
 668 }
 669
 670 static struct idset *slow_subchannel_set;
 671 static DEFINE_SPINLOCK(slow_subchannel_lock);
 672 static DECLARE_WAIT_QUEUE_HEAD(css_eval_wq);
 673 static atomic_t css_eval_scheduled;
 674
 675 static int __init slow_subchannel_init(void)
 676 {
 677         atomic_set(&css_eval_scheduled, 0);
 678         slow_subchannel_set = idset_sch_new();
 679         if (!slow_subchannel_set) {
 680                 CIO_MSG_EVENT(0, "could not allocate slow subchannel set\n");
 681                 return -ENOMEM;
 682         }
 683         return 0;
 684 }
 685
 686 static int slow_eval_known_fn(struct subchannel *sch, void *data)
 687 {
 688         int eval;
 689         int rc;
 690
 691         spin_lock_irq(&slow_subchannel_lock);
 692         eval = idset_sch_contains(slow_subchannel_set, sch->schid);
 693         idset_sch_del(slow_subchannel_set, sch->schid);
 694         spin_unlock_irq(&slow_subchannel_lock);
 695         if (eval) {
 696                 rc = css_evaluate_known_subchannel(sch, 1);
 697                 if (rc == -EAGAIN)
 698                         css_schedule_eval(sch->schid);
 699                 /*
 700                  * The loop might take long time for platforms with lots of
 701                  * known devices. Allow scheduling here.
 702                  */
 703                 cond_resched();
 704         }
 705         return 0;
 706 }
 707
 708 static int slow_eval_unknown_fn(struct subchannel_id schid, void *data)
 709 {
 710         int eval;
 711         int rc = 0;
 712
 713         spin_lock_irq(&slow_subchannel_lock);
 714         eval = idset_sch_contains(slow_subchannel_set, schid);
 715         idset_sch_del(slow_subchannel_set, schid);
 716         spin_unlock_irq(&slow_subchannel_lock);
 717         if (eval) {
 718                 rc = css_evaluate_new_subchannel(schid, 1);
 719                 switch (rc) {
 720                 case -EAGAIN:
 721                         css_schedule_eval(schid);
 722                         rc = 0;
 723                         break;
 724                 case -ENXIO:
 725                 case -ENOMEM:
 726                 case -EIO:
 727                         /* These should abort looping */
 728                         spin_lock_irq(&slow_subchannel_lock);
 729                         idset_sch_del_subseq(slow_subchannel_set, schid);
 730                         spin_unlock_irq(&slow_subchannel_lock);
 731                         break;
 732                 default:
 733                         rc = 0;
 734                 }
 735                 /* Allow scheduling here since the containing loop might
 736                  * take a while.  */
 737                 cond_resched();
 738         }
 739         return rc;
 740 }
 741
 742 static void css_slow_path_func(struct work_struct *unused)
 743 {
 744         unsigned long flags;
 745
 746         CIO_TRACE_EVENT(4, "slowpath");
 747         for_each_subchannel_staged(slow_eval_known_fn, slow_eval_unknown_fn,
 748                                    NULL);
 749         spin_lock_irqsave(&slow_subchannel_lock, flags);
 750         if (idset_is_empty(slow_subchannel_set)) {
 751                 atomic_set(&css_eval_scheduled, 0);
 752                 wake_up(&css_eval_wq);
 753         }
 754         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 755 }
 756
 757 static DECLARE_DELAYED_WORK(slow_path_work, css_slow_path_func);
 758 struct workqueue_struct *cio_work_q;
 759
 760 void css_schedule_eval(struct subchannel_id schid)
 761 {
 762         unsigned long flags;
 763
 764         spin_lock_irqsave(&slow_subchannel_lock, flags);
 765         idset_sch_add(slow_subchannel_set, schid);
 766         atomic_set(&css_eval_scheduled, 1);
 767         queue_delayed_work(cio_work_q, &slow_path_work, 0);
 768         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 769 }
 770
 771 void css_schedule_eval_all(void)
 772 {
 773         unsigned long flags;
 774
 775         spin_lock_irqsave(&slow_subchannel_lock, flags);
 776         idset_fill(slow_subchannel_set);
 777         atomic_set(&css_eval_scheduled, 1);
 778         queue_delayed_work(cio_work_q, &slow_path_work, 0);
 779         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 780 }
 781
 782 static int __unset_registered(struct device *dev, void *data)
 783 {
 784         struct idset *set = data;
 785         struct subchannel *sch = to_subchannel(dev);
 786
 787         idset_sch_del(set, sch->schid);
 788         return 0;
 789 }
 790
 791 void css_schedule_eval_all_unreg(unsigned long delay)
 792 {
 793         unsigned long flags;
 794         struct idset *unreg_set;
 795
 796         /* Find unregistered subchannels. */
 797         unreg_set = idset_sch_new();
 798         if (!unreg_set) {
 799                 /* Fallback. */
 800                 css_schedule_eval_all();
 801                 return;
 802         }
 803         idset_fill(unreg_set);
 804         bus_for_each_dev(&css_bus_type, NULL, unreg_set, __unset_registered);
 805         /* Apply to slow_subchannel_set. */
 806         spin_lock_irqsave(&slow_subchannel_lock, flags);
 807         idset_add_set(slow_subchannel_set, unreg_set);
 808         atomic_set(&css_eval_scheduled, 1);
 809         queue_delayed_work(cio_work_q, &slow_path_work, delay);
 810         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 811         idset_free(unreg_set);
 812 }
 813
 814 void css_wait_for_slow_path(void)
 815 {
 816         flush_workqueue(cio_work_q);
 817 }
 818
 819 /* Schedule reprobing of all unregistered subchannels. */
 820 void css_schedule_reprobe(void)
 821 {
 822         /* Schedule with a delay to allow merging of subsequent calls. */
 823         css_schedule_eval_all_unreg(1 * HZ);
 824 }
 825 EXPORT_SYMBOL_GPL(css_schedule_reprobe);
 826
 827 /*
 828  * Called from the machine check handler for subchannel report words.
 829  */
 830 static void css_process_crw(struct crw *crw0, struct crw *crw1, int overflow)
 831 {
 832         struct subchannel_id mchk_schid;
 833         struct subchannel *sch;
 834
 835         if (overflow) {
 836                 css_schedule_eval_all();
 837                 return;
 838         }
 839         CIO_CRW_EVENT(2, "CRW0 reports slct=%d, oflw=%d, "
 840                       "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
 841                       crw0->slct, crw0->oflw, crw0->chn, crw0->rsc, crw0->anc,
 842                       crw0->erc, crw0->rsid);
 843         if (crw1)
 844                 CIO_CRW_EVENT(2, "CRW1 reports slct=%d, oflw=%d, "
 845                               "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
 846                               crw1->slct, crw1->oflw, crw1->chn, crw1->rsc,
 847                               crw1->anc, crw1->erc, crw1->rsid);
 848         init_subchannel_id(&mchk_schid);
 849         mchk_schid.sch_no = crw0->rsid;
 850         if (crw1)
 851                 mchk_schid.ssid = (crw1->rsid >> 4) & 3;
 852
 853         if (crw0->erc == CRW_ERC_PMOD) {
 854                 sch = get_subchannel_by_schid(mchk_schid);
 855                 if (sch) {
 856                         css_update_ssd_info(sch);
 857                         put_device(&sch->dev);
 858                 }
 859         }
 860         /*
 861          * Since we are always presented with IPI in the CRW, we have to
 862          * use stsch() to find out if the subchannel in question has come
 863          * or gone.
 864          */
 865         css_evaluate_subchannel(mchk_schid, 0);
 866 }
 867
 868 static void __init
 869 css_generate_pgid(struct channel_subsystem *css, u32 tod_high)
 870 {
 871         struct cpuid cpu_id;
 872
 873         if (css_general_characteristics.mcss) {
 874                 css->global_pgid.pgid_high.ext_cssid.version = 0x80;
 875                 css->global_pgid.pgid_high.ext_cssid.cssid =
 876                         css->id_valid ? css->cssid : 0;
 877         } else {
 878                 css->global_pgid.pgid_high.cpu_addr = stap();
 879         }
 880         get_cpu_id(&cpu_id);
 881         css->global_pgid.cpu_id = cpu_id.ident;
 882         css->global_pgid.cpu_model = cpu_id.machine;
 883         css->global_pgid.tod_high = tod_high;
 884 }
 885
 886 static void channel_subsystem_release(struct device *dev)
 887 {
 888         struct channel_subsystem *css = to_css(dev);
 889
 890         mutex_destroy(&css->mutex);
 891         kfree(css);
 892 }
 893
 894 static ssize_t real_cssid_show(struct device *dev, struct device_attribute *a,
 895                                char *buf)
 896 {
 897         struct channel_subsystem *css = to_css(dev);
 898
 899         if (!css->id_valid)
 900                 return -EINVAL;
 901
 902         return sprintf(buf, "%x\n", css->cssid);
 903 }
 904 static DEVICE_ATTR_RO(real_cssid);
 905
 906 static ssize_t rescan_store(struct device *dev, struct device_attribute *a,
 907                             const char *buf, size_t count)
 908 {
 909         CIO_TRACE_EVENT(4, "usr-rescan");
 910
 911         css_schedule_eval_all();
 912         css_complete_work();
 913
 914         return count;
 915 }
 916 static DEVICE_ATTR_WO(rescan);
 917
 918 static ssize_t cm_enable_show(struct device *dev, struct device_attribute *a,
 919                               char *buf)
 920 {
 921         struct channel_subsystem *css = to_css(dev);
 922         int ret;
 923
 924         mutex_lock(&css->mutex);
 925         ret = sprintf(buf, "%x\n", css->cm_enabled);
 926         mutex_unlock(&css->mutex);
 927         return ret;
 928 }
 929
 930 static ssize_t cm_enable_store(struct device *dev, struct device_attribute *a,
 931                                const char *buf, size_t count)
 932 {
 933         struct channel_subsystem *css = to_css(dev);
 934         unsigned long val;
 935         int ret;
 936
 937         ret = kstrtoul(buf, 16, &val);
 938         if (ret)
 939                 return ret;
 940         mutex_lock(&css->mutex);
 941         switch (val) {
 942         case 0:
 943                 ret = css->cm_enabled ? chsc_secm(css, 0) : 0;
 944                 break;
 945         case 1:
 946                 ret = css->cm_enabled ? 0 : chsc_secm(css, 1);
 947                 break;
 948         default:
 949                 ret = -EINVAL;
 950         }
 951         mutex_unlock(&css->mutex);
 952         return ret < 0 ? ret : count;
 953 }
 954 static DEVICE_ATTR_RW(cm_enable);
 955
 956 static umode_t cm_enable_mode(struct kobject *kobj, struct attribute *attr,
 957                               int index)
 958 {
 959         return css_chsc_characteristics.secm ? attr->mode : 0;
 960 }
 961
 962 static struct attribute *cssdev_attrs[] = {
 963         &dev_attr_real_cssid.attr,
 964         &dev_attr_rescan.attr,
 965         NULL,
 966 };
 967
 968 static struct attribute_group cssdev_attr_group = {
 969         .attrs = cssdev_attrs,
 970 };
 971
 972 static struct attribute *cssdev_cm_attrs[] = {
 973         &dev_attr_cm_enable.attr,
 974         NULL,
 975 };
 976
 977 static struct attribute_group cssdev_cm_attr_group = {
 978         .attrs = cssdev_cm_attrs,
 979         .is_visible = cm_enable_mode,
 980 };
 981
 982 static const struct attribute_group *cssdev_attr_groups[] = {
 983         &cssdev_attr_group,
 984         &cssdev_cm_attr_group,
 985         NULL,
 986 };
 987
 988 static int __init setup_css(int nr)
 989 {
 990         struct channel_subsystem *css;
 991         int ret;
 992
 993         css = kzalloc(sizeof(*css), GFP_KERNEL);
 994         if (!css)
 995                 return -ENOMEM;
 996
 997         channel_subsystems[nr] = css;
 998         dev_set_name(&css->device, "css%x", nr);
 999         css->device.groups = cssdev_attr_groups;
1000         css->device.release = channel_subsystem_release;
1001         /*
1002          * We currently allocate notifier bits with this (using
1003          * css->device as the device argument with the DMA API)
1004          * and are fine with 64 bit addresses.
1005          */
1006         ret = dma_coerce_mask_and_coherent(&css->device, DMA_BIT_MASK(64));
1007         if (ret) {
1008                 kfree(css);
1009                 goto out_err;
1010         }
1011
1012         mutex_init(&css->mutex);
1013         ret = chsc_get_cssid_iid(nr, &css->cssid, &css->iid);
1014         if (!ret) {
1015                 css->id_valid = true;
1016                 pr_info("Partition identifier %01x.%01x\n", css->cssid,
1017                         css->iid);
1018         }
1019         css_generate_pgid(css, (u32) (get_tod_clock() >> 32));
1020
1021         ret = device_register(&css->device);
1022         if (ret) {
1023                 put_device(&css->device);
1024                 goto out_err;
1025         }
1026
1027         css->pseudo_subchannel = kzalloc(sizeof(*css->pseudo_subchannel),
1028                                          GFP_KERNEL);
1029         if (!css->pseudo_subchannel) {
1030                 device_unregister(&css->device);
1031                 ret = -ENOMEM;
1032                 goto out_err;
1033         }
1034
1035         css->pseudo_subchannel->dev.parent = &css->device;
1036         css->pseudo_subchannel->dev.release = css_subchannel_release;
1037         mutex_init(&css->pseudo_subchannel->reg_mutex);
1038         ret = css_sch_create_locks(css->pseudo_subchannel);
1039         if (ret) {
1040                 kfree(css->pseudo_subchannel);
1041                 device_unregister(&css->device);
1042                 goto out_err;
1043         }
1044
1045         dev_set_name(&css->pseudo_subchannel->dev, "defunct");
1046         ret = device_register(&css->pseudo_subchannel->dev);
1047         if (ret) {
1048                 put_device(&css->pseudo_subchannel->dev);
1049                 device_unregister(&css->device);
1050                 goto out_err;
1051         }
1052
1053         return ret;
1054 out_err:
1055         channel_subsystems[nr] = NULL;
1056         return ret;
1057 }
1058
1059 static int css_reboot_event(struct notifier_block *this,
1060                             unsigned long event,
1061                             void *ptr)
1062 {
1063         struct channel_subsystem *css;
1064         int ret;
1065
1066         ret = NOTIFY_DONE;
1067         for_each_css(css) {
1068                 mutex_lock(&css->mutex);
1069                 if (css->cm_enabled)
1070                         if (chsc_secm(css, 0))
1071                                 ret = NOTIFY_BAD;
1072                 mutex_unlock(&css->mutex);
1073         }
1074
1075         return ret;
1076 }
1077
1078 static struct notifier_block css_reboot_notifier = {
1079         .notifier_call = css_reboot_event,
1080 };
1081
1082 #define  CIO_DMA_GFP (GFP_KERNEL | __GFP_ZERO)
1083 static struct gen_pool *cio_dma_pool;
1084
1085 /* Currently cio supports only a single css */
1086 struct device *cio_get_dma_css_dev(void)
1087 {
1088         return &channel_subsystems[0]->device;
1089 }
1090
1091 struct gen_pool *cio_gp_dma_create(struct device *dma_dev, int nr_pages)
1092 {
1093         struct gen_pool *gp_dma;
1094         void *cpu_addr;
1095         dma_addr_t dma_addr;
1096         int i;
1097
1098         gp_dma = gen_pool_create(3, -1);
1099         if (!gp_dma)
1100                 return NULL;
1101         for (i = 0; i < nr_pages; ++i) {
1102                 cpu_addr = dma_alloc_coherent(dma_dev, PAGE_SIZE, &dma_addr,
1103                                               CIO_DMA_GFP);
1104                 if (!cpu_addr)
1105                         return gp_dma;
1106                 gen_pool_add_virt(gp_dma, (unsigned long) cpu_addr,
1107                                   dma_addr, PAGE_SIZE, -1);
1108         }
1109         return gp_dma;
1110 }
1111
1112 static void __gp_dma_free_dma(struct gen_pool *pool,
1113                               struct gen_pool_chunk *chunk, void *data)
1114 {
1115         size_t chunk_size = chunk->end_addr - chunk->start_addr + 1;
1116
1117         dma_free_coherent((struct device *) data, chunk_size,
1118                          (void *) chunk->start_addr,
1119                          (dma_addr_t) chunk->phys_addr);
1120 }
1121
1122 void cio_gp_dma_destroy(struct gen_pool *gp_dma, struct device *dma_dev)
1123 {
1124         if (!gp_dma)
1125                 return;
1126         /* this is quite ugly but no better idea */
1127         gen_pool_for_each_chunk(gp_dma, __gp_dma_free_dma, dma_dev);
1128         gen_pool_destroy(gp_dma);
1129 }
1130
1131 static int cio_dma_pool_init(void)
1132 {
1133         /* No need to free up the resources: compiled in */
1134         cio_dma_pool = cio_gp_dma_create(cio_get_dma_css_dev(), 1);
1135         if (!cio_dma_pool)
1136                 return -ENOMEM;
1137         return 0;
1138 }
1139
1140 void *cio_gp_dma_zalloc(struct gen_pool *gp_dma, struct device *dma_dev,
1141                         size_t size)
1142 {
1143         dma_addr_t dma_addr;
1144         unsigned long addr;
1145         size_t chunk_size;
1146
1147         if (!gp_dma)
1148                 return NULL;
1149         addr = gen_pool_alloc(gp_dma, size);
1150         while (!addr) {
1151                 chunk_size = round_up(size, PAGE_SIZE);
1152                 addr = (unsigned long) dma_alloc_coherent(dma_dev,
1153                                          chunk_size, &dma_addr, CIO_DMA_GFP);
1154                 if (!addr)
1155                         return NULL;
1156                 gen_pool_add_virt(gp_dma, addr, dma_addr, chunk_size, -1);
1157                 addr = gen_pool_alloc(gp_dma, size);
1158         }
1159         return (void *) addr;
1160 }
1161
1162 void cio_gp_dma_free(struct gen_pool *gp_dma, void *cpu_addr, size_t size)
1163 {
1164         if (!cpu_addr)
1165                 return;
1166         memset(cpu_addr, 0, size);
1167         gen_pool_free(gp_dma, (unsigned long) cpu_addr, size);
1168 }
1169
1170 /*
1171  * Allocate dma memory from the css global pool. Intended for memory not
1172  * specific to any single device within the css. The allocated memory
1173  * is not guaranteed to be 31-bit addressable.
1174  *
1175  * Caution: Not suitable for early stuff like console.
1176  */
1177 void *cio_dma_zalloc(size_t size)
1178 {
1179         return cio_gp_dma_zalloc(cio_dma_pool, cio_get_dma_css_dev(), size);
1180 }
1181
1182 void cio_dma_free(void *cpu_addr, size_t size)
1183 {
1184         cio_gp_dma_free(cio_dma_pool, cpu_addr, size);
1185 }
1186
1187 /*
1188  * Now that the driver core is running, we can setup our channel subsystem.
1189  * The struct subchannel's are created during probing.
1190  */
1191 static int __init css_bus_init(void)
1192 {
1193         int ret, i;
1194
1195         ret = chsc_init();
1196         if (ret)
1197                 return ret;
1198
1199         chsc_determine_css_characteristics();
1200         /* Try to enable MSS. */
1201         ret = chsc_enable_facility(CHSC_SDA_OC_MSS);
1202         if (ret)
1203                 max_ssid = 0;
1204         else /* Success. */
1205                 max_ssid = __MAX_SSID;
1206
1207         ret = slow_subchannel_init();
1208         if (ret)
1209                 goto out;
1210
1211         ret = crw_register_handler(CRW_RSC_SCH, css_process_crw);
1212         if (ret)
1213                 goto out;
1214
1215         if ((ret = bus_register(&css_bus_type)))
1216                 goto out;
1217
1218         /* Setup css structure. */
1219         for (i = 0; i <= MAX_CSS_IDX; i++) {
1220                 ret = setup_css(i);
1221                 if (ret)
1222                         goto out_unregister;
1223         }
1224         ret = register_reboot_notifier(&css_reboot_notifier);
1225         if (ret)
1226                 goto out_unregister;
1227         ret = cio_dma_pool_init();
1228         if (ret)
1229                 goto out_unregister_rn;
1230         airq_init();
1231         css_init_done = 1;
1232
1233         /* Enable default isc for I/O subchannels. */
1234         isc_register(IO_SCH_ISC);
1235
1236         return 0;
1237 out_unregister_rn:
1238         unregister_reboot_notifier(&css_reboot_notifier);
1239 out_unregister:
1240         while (i-- > 0) {
1241                 struct channel_subsystem *css = channel_subsystems[i];
1242                 device_unregister(&css->pseudo_subchannel->dev);
1243                 device_unregister(&css->device);
1244         }
1245         bus_unregister(&css_bus_type);
1246 out:
1247         crw_unregister_handler(CRW_RSC_SCH);
1248         idset_free(slow_subchannel_set);
1249         chsc_init_cleanup();
1250         pr_alert("The CSS device driver initialization failed with "
1251                  "errno=%d\n", ret);
1252         return ret;
1253 }
1254
1255 static void __init css_bus_cleanup(void)
1256 {
1257         struct channel_subsystem *css;
1258
1259         for_each_css(css) {
1260                 device_unregister(&css->pseudo_subchannel->dev);
1261                 device_unregister(&css->device);
1262         }
1263         bus_unregister(&css_bus_type);
1264         crw_unregister_handler(CRW_RSC_SCH);
1265         idset_free(slow_subchannel_set);
1266         chsc_init_cleanup();
1267         isc_unregister(IO_SCH_ISC);
1268 }
1269
1270 static int __init channel_subsystem_init(void)
1271 {
1272         int ret;
1273
1274         ret = css_bus_init();
1275         if (ret)
1276                 return ret;
1277         cio_work_q = create_singlethread_workqueue("cio");
1278         if (!cio_work_q) {
1279                 ret = -ENOMEM;
1280                 goto out_bus;
1281         }
1282         ret = io_subchannel_init();
1283         if (ret)
1284                 goto out_wq;
1285
1286         /* Register subchannels which are already in use. */
1287         cio_register_early_subchannels();
1288         /* Start initial subchannel evaluation. */
1289         css_schedule_eval_all();
1290
1291         return ret;
1292 out_wq:
1293         destroy_workqueue(cio_work_q);
1294 out_bus:
1295         css_bus_cleanup();
1296         return ret;
1297 }
1298 subsys_initcall(channel_subsystem_init);
1299
1300 static int css_settle(struct device_driver *drv, void *unused)
1301 {
1302         struct css_driver *cssdrv = to_cssdriver(drv);
1303
1304         if (cssdrv->settle)
1305                 return cssdrv->settle();
1306         return 0;
1307 }
1308
1309 int css_complete_work(void)
1310 {
1311         int ret;
1312
1313         /* Wait for the evaluation of subchannels to finish. */
1314         ret = wait_event_interruptible(css_eval_wq,
1315                                        atomic_read(&css_eval_scheduled) == 0);
1316         if (ret)
1317                 return -EINTR;
1318         flush_workqueue(cio_work_q);
1319         /* Wait for the subchannel type specific initialization to finish */
1320         return bus_for_each_drv(&css_bus_type, NULL, NULL, css_settle);
1321 }
1322
1323
1324 /*
1325  * Wait for the initialization of devices to finish, to make sure we are
1326  * done with our setup if the search for the root device starts.
1327  */
1328 static int __init channel_subsystem_init_sync(void)
1329 {
1330         css_complete_work();
1331         return 0;
1332 }
1333 subsys_initcall_sync(channel_subsystem_init_sync);
1334
1335 #ifdef CONFIG_PROC_FS
1336 static ssize_t cio_settle_write(struct file *file, const char __user *buf,
1337                                 size_t count, loff_t *ppos)
1338 {
1339         int ret;
1340
1341         /* Handle pending CRW's. */
1342         crw_wait_for_channel_report();
1343         ret = css_complete_work();
1344
1345         return ret ? ret : count;
1346 }
1347
1348 static const struct proc_ops cio_settle_proc_ops = {
1349         .proc_open      = nonseekable_open,
1350         .proc_write     = cio_settle_write,
1351         .proc_lseek     = no_llseek,
1352 };
1353
1354 static int __init cio_settle_init(void)
1355 {
1356         struct proc_dir_entry *entry;
1357
1358         entry = proc_create("cio_settle", S_IWUSR, NULL, &cio_settle_proc_ops);
1359         if (!entry)
1360                 return -ENOMEM;
1361         return 0;
1362 }
1363 device_initcall(cio_settle_init);
1364 #endif /*CONFIG_PROC_FS*/
1365
1366 int sch_is_pseudo_sch(struct subchannel *sch)
1367 {
1368         if (!sch->dev.parent)
1369                 return 0;
1370         return sch == to_css(sch->dev.parent)->pseudo_subchannel;
1371 }
1372
1373 static int css_bus_match(struct device *dev, struct device_driver *drv)
1374 {
1375         struct subchannel *sch = to_subchannel(dev);
1376         struct css_driver *driver = to_cssdriver(drv);
1377         struct css_device_id *id;
1378
1379         /* When driver_override is set, only bind to the matching driver */
1380         if (sch->driver_override && strcmp(sch->driver_override, drv->name))
1381                 return 0;
1382
1383         for (id = driver->subchannel_type; id->match_flags; id++) {
1384                 if (sch->st == id->type)
1385                         return 1;
1386         }
1387
1388         return 0;
1389 }
1390
1391 static int css_probe(struct device *dev)
1392 {
1393         struct subchannel *sch;
1394         int ret;
1395
1396         sch = to_subchannel(dev);
1397         sch->driver = to_cssdriver(dev->driver);
1398         ret = sch->driver->probe ? sch->driver->probe(sch) : 0;
1399         if (ret)
1400                 sch->driver = NULL;
1401         return ret;
1402 }
1403
1404 static void css_remove(struct device *dev)
1405 {
1406         struct subchannel *sch;
1407
1408         sch = to_subchannel(dev);
1409         if (sch->driver->remove)
1410                 sch->driver->remove(sch);
1411         sch->driver = NULL;
1412 }
1413
1414 static void css_shutdown(struct device *dev)
1415 {
1416         struct subchannel *sch;
1417
1418         sch = to_subchannel(dev);
1419         if (sch->driver && sch->driver->shutdown)
1420                 sch->driver->shutdown(sch);
1421 }
1422
1423 static int css_uevent(struct device *dev, struct kobj_uevent_env *env)
1424 {
1425         struct subchannel *sch = to_subchannel(dev);
1426         int ret;
1427
1428         ret = add_uevent_var(env, "ST=%01X", sch->st);
1429         if (ret)
1430                 return ret;
1431         ret = add_uevent_var(env, "MODALIAS=css:t%01X", sch->st);
1432         return ret;
1433 }
1434
1435 static struct bus_type css_bus_type = {
1436         .name     = "css",
1437         .match    = css_bus_match,
1438         .probe    = css_probe,
1439         .remove   = css_remove,
1440         .shutdown = css_shutdown,
1441         .uevent   = css_uevent,
1442 };
1443
1444 /**
1445  * css_driver_register - register a css driver
1446  * @cdrv: css driver to register
1447  *
1448  * This is mainly a wrapper around driver_register that sets name
1449  * and bus_type in the embedded struct device_driver correctly.
1450  */
1451 int css_driver_register(struct css_driver *cdrv)
1452 {
1453         cdrv->drv.bus = &css_bus_type;
1454         return driver_register(&cdrv->drv);
1455 }
1456 EXPORT_SYMBOL_GPL(css_driver_register);
1457
1458 /**
1459  * css_driver_unregister - unregister a css driver
1460  * @cdrv: css driver to unregister
1461  *
1462  * This is a wrapper around driver_unregister.
1463  */
1464 void css_driver_unregister(struct css_driver *cdrv)
1465 {
1466         driver_unregister(&cdrv->drv);
1467 }
1468 EXPORT_SYMBOL_GPL(css_driver_unregister);