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