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 ([email protected])
   8  *            Cornelia Huck ([email protected])
   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         int ret;
 342
 343         ret = driver_set_override(dev, &sch->driver_override, buf, count);
 344         if (ret)
 345                 return ret;
 346
 347         return count;
 348 }
 349
 350 static ssize_t driver_override_show(struct device *dev,
 351                                     struct device_attribute *attr, char *buf)
 352 {
 353         struct subchannel *sch = to_subchannel(dev);
 354         ssize_t len;
 355
 356         device_lock(dev);
 357         len = snprintf(buf, PAGE_SIZE, "%s\n", sch->driver_override);
 358         device_unlock(dev);
 359         return len;
 360 }
 361 static DEVICE_ATTR_RW(driver_override);
 362
 363 static struct attribute *subch_attrs[] = {
 364         &dev_attr_type.attr,
 365         &dev_attr_modalias.attr,
 366         &dev_attr_driver_override.attr,
 367         NULL,
 368 };
 369
 370 static struct attribute_group subch_attr_group = {
 371         .attrs = subch_attrs,
 372 };
 373
 374 static const struct attribute_group *default_subch_attr_groups[] = {
 375         &subch_attr_group,
 376         NULL,
 377 };
 378
 379 static ssize_t chpids_show(struct device *dev,
 380                            struct device_attribute *attr,
 381                            char *buf)
 382 {
 383         struct subchannel *sch = to_subchannel(dev);
 384         struct chsc_ssd_info *ssd = &sch->ssd_info;
 385         ssize_t ret = 0;
 386         int mask;
 387         int chp;
 388
 389         for (chp = 0; chp < 8; chp++) {
 390                 mask = 0x80 >> chp;
 391                 if (ssd->path_mask & mask)
 392                         ret += sprintf(buf + ret, "%02x ", ssd->chpid[chp].id);
 393                 else
 394                         ret += sprintf(buf + ret, "00 ");
 395         }
 396         ret += sprintf(buf + ret, "\n");
 397         return ret;
 398 }
 399 static DEVICE_ATTR_RO(chpids);
 400
 401 static ssize_t pimpampom_show(struct device *dev,
 402                               struct device_attribute *attr,
 403                               char *buf)
 404 {
 405         struct subchannel *sch = to_subchannel(dev);
 406         struct pmcw *pmcw = &sch->schib.pmcw;
 407
 408         return sprintf(buf, "%02x %02x %02x\n",
 409                        pmcw->pim, pmcw->pam, pmcw->pom);
 410 }
 411 static DEVICE_ATTR_RO(pimpampom);
 412
 413 static ssize_t dev_busid_show(struct device *dev,
 414                               struct device_attribute *attr,
 415                               char *buf)
 416 {
 417         struct subchannel *sch = to_subchannel(dev);
 418         struct pmcw *pmcw = &sch->schib.pmcw;
 419
 420         if ((pmcw->st == SUBCHANNEL_TYPE_IO && pmcw->dnv) ||
 421             (pmcw->st == SUBCHANNEL_TYPE_MSG && pmcw->w))
 422                 return sysfs_emit(buf, "0.%x.%04x\n", sch->schid.ssid,
 423                                   pmcw->dev);
 424         else
 425                 return sysfs_emit(buf, "none\n");
 426 }
 427 static DEVICE_ATTR_RO(dev_busid);
 428
 429 static struct attribute *io_subchannel_type_attrs[] = {
 430         &dev_attr_chpids.attr,
 431         &dev_attr_pimpampom.attr,
 432         &dev_attr_dev_busid.attr,
 433         NULL,
 434 };
 435 ATTRIBUTE_GROUPS(io_subchannel_type);
 436
 437 static const struct device_type io_subchannel_type = {
 438         .groups = io_subchannel_type_groups,
 439 };
 440
 441 int css_register_subchannel(struct subchannel *sch)
 442 {
 443         int ret;
 444
 445         /* Initialize the subchannel structure */
 446         sch->dev.parent = &channel_subsystems[0]->device;
 447         sch->dev.bus = &css_bus_type;
 448         sch->dev.groups = default_subch_attr_groups;
 449
 450         if (sch->st == SUBCHANNEL_TYPE_IO)
 451                 sch->dev.type = &io_subchannel_type;
 452
 453         css_update_ssd_info(sch);
 454         /* make it known to the system */
 455         ret = css_sch_device_register(sch);
 456         if (ret) {
 457                 CIO_MSG_EVENT(0, "Could not register sch 0.%x.%04x: %d\n",
 458                               sch->schid.ssid, sch->schid.sch_no, ret);
 459                 return ret;
 460         }
 461         return ret;
 462 }
 463
 464 static int css_probe_device(struct subchannel_id schid, struct schib *schib)
 465 {
 466         struct subchannel *sch;
 467         int ret;
 468
 469         sch = css_alloc_subchannel(schid, schib);
 470         if (IS_ERR(sch))
 471                 return PTR_ERR(sch);
 472
 473         ret = css_register_subchannel(sch);
 474         if (ret)
 475                 put_device(&sch->dev);
 476
 477         return ret;
 478 }
 479
 480 static int
 481 check_subchannel(struct device *dev, const void *data)
 482 {
 483         struct subchannel *sch;
 484         struct subchannel_id *schid = (void *)data;
 485
 486         sch = to_subchannel(dev);
 487         return schid_equal(&sch->schid, schid);
 488 }
 489
 490 struct subchannel *
 491 get_subchannel_by_schid(struct subchannel_id schid)
 492 {
 493         struct device *dev;
 494
 495         dev = bus_find_device(&css_bus_type, NULL,
 496                               &schid, check_subchannel);
 497
 498         return dev ? to_subchannel(dev) : NULL;
 499 }
 500
 501 /**
 502  * css_sch_is_valid() - check if a subchannel is valid
 503  * @schib: subchannel information block for the subchannel
 504  */
 505 int css_sch_is_valid(struct schib *schib)
 506 {
 507         if ((schib->pmcw.st == SUBCHANNEL_TYPE_IO) && !schib->pmcw.dnv)
 508                 return 0;
 509         if ((schib->pmcw.st == SUBCHANNEL_TYPE_MSG) && !schib->pmcw.w)
 510                 return 0;
 511         return 1;
 512 }
 513 EXPORT_SYMBOL_GPL(css_sch_is_valid);
 514
 515 static int css_evaluate_new_subchannel(struct subchannel_id schid, int slow)
 516 {
 517         struct schib schib;
 518         int ccode;
 519
 520         if (!slow) {
 521                 /* Will be done on the slow path. */
 522                 return -EAGAIN;
 523         }
 524         /*
 525          * The first subchannel that is not-operational (ccode==3)
 526          * indicates that there aren't any more devices available.
 527          * If stsch gets an exception, it means the current subchannel set
 528          * is not valid.
 529          */
 530         ccode = stsch(schid, &schib);
 531         if (ccode)
 532                 return (ccode == 3) ? -ENXIO : ccode;
 533
 534         return css_probe_device(schid, &schib);
 535 }
 536
 537 static int css_evaluate_known_subchannel(struct subchannel *sch, int slow)
 538 {
 539         int ret = 0;
 540
 541         if (sch->driver) {
 542                 if (sch->driver->sch_event)
 543                         ret = sch->driver->sch_event(sch, slow);
 544                 else
 545                         dev_dbg(&sch->dev,
 546                                 "Got subchannel machine check but "
 547                                 "no sch_event handler provided.\n");
 548         }
 549         if (ret != 0 && ret != -EAGAIN) {
 550                 CIO_MSG_EVENT(2, "eval: sch 0.%x.%04x, rc=%d\n",
 551                               sch->schid.ssid, sch->schid.sch_no, ret);
 552         }
 553         return ret;
 554 }
 555
 556 static void css_evaluate_subchannel(struct subchannel_id schid, int slow)
 557 {
 558         struct subchannel *sch;
 559         int ret;
 560
 561         sch = get_subchannel_by_schid(schid);
 562         if (sch) {
 563                 ret = css_evaluate_known_subchannel(sch, slow);
 564                 put_device(&sch->dev);
 565         } else
 566                 ret = css_evaluate_new_subchannel(schid, slow);
 567         if (ret == -EAGAIN)
 568                 css_schedule_eval(schid);
 569 }
 570
 571 /**
 572  * css_sched_sch_todo - schedule a subchannel operation
 573  * @sch: subchannel
 574  * @todo: todo
 575  *
 576  * Schedule the operation identified by @todo to be performed on the slow path
 577  * workqueue. Do nothing if another operation with higher priority is already
 578  * scheduled. Needs to be called with subchannel lock held.
 579  */
 580 void css_sched_sch_todo(struct subchannel *sch, enum sch_todo todo)
 581 {
 582         CIO_MSG_EVENT(4, "sch_todo: sched sch=0.%x.%04x todo=%d\n",
 583                       sch->schid.ssid, sch->schid.sch_no, todo);
 584         if (sch->todo >= todo)
 585                 return;
 586         /* Get workqueue ref. */
 587         if (!get_device(&sch->dev))
 588                 return;
 589         sch->todo = todo;
 590         if (!queue_work(cio_work_q, &sch->todo_work)) {
 591                 /* Already queued, release workqueue ref. */
 592                 put_device(&sch->dev);
 593         }
 594 }
 595 EXPORT_SYMBOL_GPL(css_sched_sch_todo);
 596
 597 static void css_sch_todo(struct work_struct *work)
 598 {
 599         struct subchannel *sch;
 600         enum sch_todo todo;
 601         int ret;
 602
 603         sch = container_of(work, struct subchannel, todo_work);
 604         /* Find out todo. */
 605         spin_lock_irq(sch->lock);
 606         todo = sch->todo;
 607         CIO_MSG_EVENT(4, "sch_todo: sch=0.%x.%04x, todo=%d\n", sch->schid.ssid,
 608                       sch->schid.sch_no, todo);
 609         sch->todo = SCH_TODO_NOTHING;
 610         spin_unlock_irq(sch->lock);
 611         /* Perform todo. */
 612         switch (todo) {
 613         case SCH_TODO_NOTHING:
 614                 break;
 615         case SCH_TODO_EVAL:
 616                 ret = css_evaluate_known_subchannel(sch, 1);
 617                 if (ret == -EAGAIN) {
 618                         spin_lock_irq(sch->lock);
 619                         css_sched_sch_todo(sch, todo);
 620                         spin_unlock_irq(sch->lock);
 621                 }
 622                 break;
 623         case SCH_TODO_UNREG:
 624                 css_sch_device_unregister(sch);
 625                 break;
 626         }
 627         /* Release workqueue ref. */
 628         put_device(&sch->dev);
 629 }
 630
 631 static struct idset *slow_subchannel_set;
 632 static DEFINE_SPINLOCK(slow_subchannel_lock);
 633 static DECLARE_WAIT_QUEUE_HEAD(css_eval_wq);
 634 static atomic_t css_eval_scheduled;
 635
 636 static int __init slow_subchannel_init(void)
 637 {
 638         atomic_set(&css_eval_scheduled, 0);
 639         slow_subchannel_set = idset_sch_new();
 640         if (!slow_subchannel_set) {
 641                 CIO_MSG_EVENT(0, "could not allocate slow subchannel set\n");
 642                 return -ENOMEM;
 643         }
 644         return 0;
 645 }
 646
 647 static int slow_eval_known_fn(struct subchannel *sch, void *data)
 648 {
 649         int eval;
 650         int rc;
 651
 652         spin_lock_irq(&slow_subchannel_lock);
 653         eval = idset_sch_contains(slow_subchannel_set, sch->schid);
 654         idset_sch_del(slow_subchannel_set, sch->schid);
 655         spin_unlock_irq(&slow_subchannel_lock);
 656         if (eval) {
 657                 rc = css_evaluate_known_subchannel(sch, 1);
 658                 if (rc == -EAGAIN)
 659                         css_schedule_eval(sch->schid);
 660                 /*
 661                  * The loop might take long time for platforms with lots of
 662                  * known devices. Allow scheduling here.
 663                  */
 664                 cond_resched();
 665         }
 666         return 0;
 667 }
 668
 669 static int slow_eval_unknown_fn(struct subchannel_id schid, void *data)
 670 {
 671         int eval;
 672         int rc = 0;
 673
 674         spin_lock_irq(&slow_subchannel_lock);
 675         eval = idset_sch_contains(slow_subchannel_set, schid);
 676         idset_sch_del(slow_subchannel_set, schid);
 677         spin_unlock_irq(&slow_subchannel_lock);
 678         if (eval) {
 679                 rc = css_evaluate_new_subchannel(schid, 1);
 680                 switch (rc) {
 681                 case -EAGAIN:
 682                         css_schedule_eval(schid);
 683                         rc = 0;
 684                         break;
 685                 case -ENXIO:
 686                 case -ENOMEM:
 687                 case -EIO:
 688                         /* These should abort looping */
 689                         spin_lock_irq(&slow_subchannel_lock);
 690                         idset_sch_del_subseq(slow_subchannel_set, schid);
 691                         spin_unlock_irq(&slow_subchannel_lock);
 692                         break;
 693                 default:
 694                         rc = 0;
 695                 }
 696                 /* Allow scheduling here since the containing loop might
 697                  * take a while.  */
 698                 cond_resched();
 699         }
 700         return rc;
 701 }
 702
 703 static void css_slow_path_func(struct work_struct *unused)
 704 {
 705         unsigned long flags;
 706
 707         CIO_TRACE_EVENT(4, "slowpath");
 708         for_each_subchannel_staged(slow_eval_known_fn, slow_eval_unknown_fn,
 709                                    NULL);
 710         spin_lock_irqsave(&slow_subchannel_lock, flags);
 711         if (idset_is_empty(slow_subchannel_set)) {
 712                 atomic_set(&css_eval_scheduled, 0);
 713                 wake_up(&css_eval_wq);
 714         }
 715         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 716 }
 717
 718 static DECLARE_DELAYED_WORK(slow_path_work, css_slow_path_func);
 719 struct workqueue_struct *cio_work_q;
 720
 721 void css_schedule_eval(struct subchannel_id schid)
 722 {
 723         unsigned long flags;
 724
 725         spin_lock_irqsave(&slow_subchannel_lock, flags);
 726         idset_sch_add(slow_subchannel_set, schid);
 727         atomic_set(&css_eval_scheduled, 1);
 728         queue_delayed_work(cio_work_q, &slow_path_work, 0);
 729         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 730 }
 731
 732 void css_schedule_eval_all(void)
 733 {
 734         unsigned long flags;
 735
 736         spin_lock_irqsave(&slow_subchannel_lock, flags);
 737         idset_fill(slow_subchannel_set);
 738         atomic_set(&css_eval_scheduled, 1);
 739         queue_delayed_work(cio_work_q, &slow_path_work, 0);
 740         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 741 }
 742
 743 static int __unset_registered(struct device *dev, void *data)
 744 {
 745         struct idset *set = data;
 746         struct subchannel *sch = to_subchannel(dev);
 747
 748         idset_sch_del(set, sch->schid);
 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         struct ccw_device *cdev;
 757
 758         if (sch->st == SUBCHANNEL_TYPE_IO) {
 759                 cdev = sch_get_cdev(sch);
 760                 if (cdev && cdev->online)
 761                         idset_sch_del(set, sch->schid);
 762         }
 763
 764         return 0;
 765 }
 766
 767 void css_schedule_eval_cond(enum css_eval_cond cond, unsigned long delay)
 768 {
 769         unsigned long flags;
 770         struct idset *set;
 771
 772         /* Find unregistered subchannels. */
 773         set = idset_sch_new();
 774         if (!set) {
 775                 /* Fallback. */
 776                 css_schedule_eval_all();
 777                 return;
 778         }
 779         idset_fill(set);
 780         switch (cond) {
 781         case CSS_EVAL_UNREG:
 782                 bus_for_each_dev(&css_bus_type, NULL, set, __unset_registered);
 783                 break;
 784         case CSS_EVAL_NOT_ONLINE:
 785                 bus_for_each_dev(&css_bus_type, NULL, set, __unset_online);
 786                 break;
 787         default:
 788                 break;
 789         }
 790
 791         /* Apply to slow_subchannel_set. */
 792         spin_lock_irqsave(&slow_subchannel_lock, flags);
 793         idset_add_set(slow_subchannel_set, set);
 794         atomic_set(&css_eval_scheduled, 1);
 795         queue_delayed_work(cio_work_q, &slow_path_work, delay);
 796         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 797         idset_free(set);
 798 }
 799
 800 void css_wait_for_slow_path(void)
 801 {
 802         flush_workqueue(cio_work_q);
 803 }
 804
 805 /* Schedule reprobing of all unregistered subchannels. */
 806 void css_schedule_reprobe(void)
 807 {
 808         /* Schedule with a delay to allow merging of subsequent calls. */
 809         css_schedule_eval_cond(CSS_EVAL_UNREG, 1 * HZ);
 810 }
 811 EXPORT_SYMBOL_GPL(css_schedule_reprobe);
 812
 813 /*
 814  * Called from the machine check handler for subchannel report words.
 815  */
 816 static void css_process_crw(struct crw *crw0, struct crw *crw1, int overflow)
 817 {
 818         struct subchannel_id mchk_schid;
 819         struct subchannel *sch;
 820
 821         if (overflow) {
 822                 css_schedule_eval_all();
 823                 return;
 824         }
 825         CIO_CRW_EVENT(2, "CRW0 reports slct=%d, oflw=%d, "
 826                       "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
 827                       crw0->slct, crw0->oflw, crw0->chn, crw0->rsc, crw0->anc,
 828                       crw0->erc, crw0->rsid);
 829         if (crw1)
 830                 CIO_CRW_EVENT(2, "CRW1 reports slct=%d, oflw=%d, "
 831                               "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
 832                               crw1->slct, crw1->oflw, crw1->chn, crw1->rsc,
 833                               crw1->anc, crw1->erc, crw1->rsid);
 834         init_subchannel_id(&mchk_schid);
 835         mchk_schid.sch_no = crw0->rsid;
 836         if (crw1)
 837                 mchk_schid.ssid = (crw1->rsid >> 4) & 3;
 838
 839         if (crw0->erc == CRW_ERC_PMOD) {
 840                 sch = get_subchannel_by_schid(mchk_schid);
 841                 if (sch) {
 842                         css_update_ssd_info(sch);
 843                         put_device(&sch->dev);
 844                 }
 845         }
 846         /*
 847          * Since we are always presented with IPI in the CRW, we have to
 848          * use stsch() to find out if the subchannel in question has come
 849          * or gone.
 850          */
 851         css_evaluate_subchannel(mchk_schid, 0);
 852 }
 853
 854 static void __init
 855 css_generate_pgid(struct channel_subsystem *css, u32 tod_high)
 856 {
 857         struct cpuid cpu_id;
 858
 859         if (css_general_characteristics.mcss) {
 860                 css->global_pgid.pgid_high.ext_cssid.version = 0x80;
 861                 css->global_pgid.pgid_high.ext_cssid.cssid =
 862                         css->id_valid ? css->cssid : 0;
 863         } else {
 864                 css->global_pgid.pgid_high.cpu_addr = stap();
 865         }
 866         get_cpu_id(&cpu_id);
 867         css->global_pgid.cpu_id = cpu_id.ident;
 868         css->global_pgid.cpu_model = cpu_id.machine;
 869         css->global_pgid.tod_high = tod_high;
 870 }
 871
 872 static void channel_subsystem_release(struct device *dev)
 873 {
 874         struct channel_subsystem *css = to_css(dev);
 875
 876         mutex_destroy(&css->mutex);
 877         kfree(css);
 878 }
 879
 880 static ssize_t real_cssid_show(struct device *dev, struct device_attribute *a,
 881                                char *buf)
 882 {
 883         struct channel_subsystem *css = to_css(dev);
 884
 885         if (!css->id_valid)
 886                 return -EINVAL;
 887
 888         return sprintf(buf, "%x\n", css->cssid);
 889 }
 890 static DEVICE_ATTR_RO(real_cssid);
 891
 892 static ssize_t rescan_store(struct device *dev, struct device_attribute *a,
 893                             const char *buf, size_t count)
 894 {
 895         CIO_TRACE_EVENT(4, "usr-rescan");
 896
 897         css_schedule_eval_all();
 898         css_complete_work();
 899
 900         return count;
 901 }
 902 static DEVICE_ATTR_WO(rescan);
 903
 904 static ssize_t cm_enable_show(struct device *dev, struct device_attribute *a,
 905                               char *buf)
 906 {
 907         struct channel_subsystem *css = to_css(dev);
 908         int ret;
 909
 910         mutex_lock(&css->mutex);
 911         ret = sprintf(buf, "%x\n", css->cm_enabled);
 912         mutex_unlock(&css->mutex);
 913         return ret;
 914 }
 915
 916 static ssize_t cm_enable_store(struct device *dev, struct device_attribute *a,
 917                                const char *buf, size_t count)
 918 {
 919         struct channel_subsystem *css = to_css(dev);
 920         unsigned long val;
 921         int ret;
 922
 923         ret = kstrtoul(buf, 16, &val);
 924         if (ret)
 925                 return ret;
 926         mutex_lock(&css->mutex);
 927         switch (val) {
 928         case 0:
 929                 ret = css->cm_enabled ? chsc_secm(css, 0) : 0;
 930                 break;
 931         case 1:
 932                 ret = css->cm_enabled ? 0 : chsc_secm(css, 1);
 933                 break;
 934         default:
 935                 ret = -EINVAL;
 936         }
 937         mutex_unlock(&css->mutex);
 938         return ret < 0 ? ret : count;
 939 }
 940 static DEVICE_ATTR_RW(cm_enable);
 941
 942 static umode_t cm_enable_mode(struct kobject *kobj, struct attribute *attr,
 943                               int index)
 944 {
 945         return css_chsc_characteristics.secm ? attr->mode : 0;
 946 }
 947
 948 static struct attribute *cssdev_attrs[] = {
 949         &dev_attr_real_cssid.attr,
 950         &dev_attr_rescan.attr,
 951         NULL,
 952 };
 953
 954 static struct attribute_group cssdev_attr_group = {
 955         .attrs = cssdev_attrs,
 956 };
 957
 958 static struct attribute *cssdev_cm_attrs[] = {
 959         &dev_attr_cm_enable.attr,
 960         NULL,
 961 };
 962
 963 static struct attribute_group cssdev_cm_attr_group = {
 964         .attrs = cssdev_cm_attrs,
 965         .is_visible = cm_enable_mode,
 966 };
 967
 968 static const struct attribute_group *cssdev_attr_groups[] = {
 969         &cssdev_attr_group,
 970         &cssdev_cm_attr_group,
 971         NULL,
 972 };
 973
 974 static int __init setup_css(int nr)
 975 {
 976         struct channel_subsystem *css;
 977         int ret;
 978
 979         css = kzalloc(sizeof(*css), GFP_KERNEL);
 980         if (!css)
 981                 return -ENOMEM;
 982
 983         channel_subsystems[nr] = css;
 984         dev_set_name(&css->device, "css%x", nr);
 985         css->device.groups = cssdev_attr_groups;
 986         css->device.release = channel_subsystem_release;
 987         /*
 988          * We currently allocate notifier bits with this (using
 989          * css->device as the device argument with the DMA API)
 990          * and are fine with 64 bit addresses.
 991          */
 992         ret = dma_coerce_mask_and_coherent(&css->device, DMA_BIT_MASK(64));
 993         if (ret) {
 994                 kfree(css);
 995                 goto out_err;
 996         }
 997
 998         mutex_init(&css->mutex);
 999         ret = chsc_get_cssid_iid(nr, &css->cssid, &css->iid);
1000         if (!ret) {
1001                 css->id_valid = true;
1002                 pr_info("Partition identifier %01x.%01x\n", css->cssid,
1003                         css->iid);
1004         }
1005         css_generate_pgid(css, (u32) (get_tod_clock() >> 32));
1006
1007         ret = device_register(&css->device);
1008         if (ret) {
1009                 put_device(&css->device);
1010                 goto out_err;
1011         }
1012
1013         css->pseudo_subchannel = kzalloc(sizeof(*css->pseudo_subchannel),
1014                                          GFP_KERNEL);
1015         if (!css->pseudo_subchannel) {
1016                 device_unregister(&css->device);
1017                 ret = -ENOMEM;
1018                 goto out_err;
1019         }
1020
1021         css->pseudo_subchannel->dev.parent = &css->device;
1022         css->pseudo_subchannel->dev.release = css_subchannel_release;
1023         mutex_init(&css->pseudo_subchannel->reg_mutex);
1024         ret = css_sch_create_locks(css->pseudo_subchannel);
1025         if (ret) {
1026                 kfree(css->pseudo_subchannel);
1027                 device_unregister(&css->device);
1028                 goto out_err;
1029         }
1030
1031         dev_set_name(&css->pseudo_subchannel->dev, "defunct");
1032         ret = device_register(&css->pseudo_subchannel->dev);
1033         if (ret) {
1034                 put_device(&css->pseudo_subchannel->dev);
1035                 device_unregister(&css->device);
1036                 goto out_err;
1037         }
1038
1039         return ret;
1040 out_err:
1041         channel_subsystems[nr] = NULL;
1042         return ret;
1043 }
1044
1045 static int css_reboot_event(struct notifier_block *this,
1046                             unsigned long event,
1047                             void *ptr)
1048 {
1049         struct channel_subsystem *css;
1050         int ret;
1051
1052         ret = NOTIFY_DONE;
1053         for_each_css(css) {
1054                 mutex_lock(&css->mutex);
1055                 if (css->cm_enabled)
1056                         if (chsc_secm(css, 0))
1057                                 ret = NOTIFY_BAD;
1058                 mutex_unlock(&css->mutex);
1059         }
1060
1061         return ret;
1062 }
1063
1064 static struct notifier_block css_reboot_notifier = {
1065         .notifier_call = css_reboot_event,
1066 };
1067
1068 #define  CIO_DMA_GFP (GFP_KERNEL | __GFP_ZERO)
1069 static struct gen_pool *cio_dma_pool;
1070
1071 /* Currently cio supports only a single css */
1072 struct device *cio_get_dma_css_dev(void)
1073 {
1074         return &channel_subsystems[0]->device;
1075 }
1076
1077 struct gen_pool *cio_gp_dma_create(struct device *dma_dev, int nr_pages)
1078 {
1079         struct gen_pool *gp_dma;
1080         void *cpu_addr;
1081         dma_addr_t dma_addr;
1082         int i;
1083
1084         gp_dma = gen_pool_create(3, -1);
1085         if (!gp_dma)
1086                 return NULL;
1087         for (i = 0; i < nr_pages; ++i) {
1088                 cpu_addr = dma_alloc_coherent(dma_dev, PAGE_SIZE, &dma_addr,
1089                                               CIO_DMA_GFP);
1090                 if (!cpu_addr)
1091                         return gp_dma;
1092                 gen_pool_add_virt(gp_dma, (unsigned long) cpu_addr,
1093                                   dma_addr, PAGE_SIZE, -1);
1094         }
1095         return gp_dma;
1096 }
1097
1098 static void __gp_dma_free_dma(struct gen_pool *pool,
1099                               struct gen_pool_chunk *chunk, void *data)
1100 {
1101         size_t chunk_size = chunk->end_addr - chunk->start_addr + 1;
1102
1103         dma_free_coherent((struct device *) data, chunk_size,
1104                          (void *) chunk->start_addr,
1105                          (dma_addr_t) chunk->phys_addr);
1106 }
1107
1108 void cio_gp_dma_destroy(struct gen_pool *gp_dma, struct device *dma_dev)
1109 {
1110         if (!gp_dma)
1111                 return;
1112         /* this is quite ugly but no better idea */
1113         gen_pool_for_each_chunk(gp_dma, __gp_dma_free_dma, dma_dev);
1114         gen_pool_destroy(gp_dma);
1115 }
1116
1117 static int cio_dma_pool_init(void)
1118 {
1119         /* No need to free up the resources: compiled in */
1120         cio_dma_pool = cio_gp_dma_create(cio_get_dma_css_dev(), 1);
1121         if (!cio_dma_pool)
1122                 return -ENOMEM;
1123         return 0;
1124 }
1125
1126 void *cio_gp_dma_zalloc(struct gen_pool *gp_dma, struct device *dma_dev,
1127                         size_t size)
1128 {
1129         dma_addr_t dma_addr;
1130         unsigned long addr;
1131         size_t chunk_size;
1132
1133         if (!gp_dma)
1134                 return NULL;
1135         addr = gen_pool_alloc(gp_dma, size);
1136         while (!addr) {
1137                 chunk_size = round_up(size, PAGE_SIZE);
1138                 addr = (unsigned long) dma_alloc_coherent(dma_dev,
1139                                          chunk_size, &dma_addr, CIO_DMA_GFP);
1140                 if (!addr)
1141                         return NULL;
1142                 gen_pool_add_virt(gp_dma, addr, dma_addr, chunk_size, -1);
1143                 addr = gen_pool_alloc(gp_dma, size);
1144         }
1145         return (void *) addr;
1146 }
1147
1148 void cio_gp_dma_free(struct gen_pool *gp_dma, void *cpu_addr, size_t size)
1149 {
1150         if (!cpu_addr)
1151                 return;
1152         memset(cpu_addr, 0, size);
1153         gen_pool_free(gp_dma, (unsigned long) cpu_addr, size);
1154 }
1155
1156 /*
1157  * Allocate dma memory from the css global pool. Intended for memory not
1158  * specific to any single device within the css. The allocated memory
1159  * is not guaranteed to be 31-bit addressable.
1160  *
1161  * Caution: Not suitable for early stuff like console.
1162  */
1163 void *cio_dma_zalloc(size_t size)
1164 {
1165         return cio_gp_dma_zalloc(cio_dma_pool, cio_get_dma_css_dev(), size);
1166 }
1167
1168 void cio_dma_free(void *cpu_addr, size_t size)
1169 {
1170         cio_gp_dma_free(cio_dma_pool, cpu_addr, size);
1171 }
1172
1173 /*
1174  * Now that the driver core is running, we can setup our channel subsystem.
1175  * The struct subchannel's are created during probing.
1176  */
1177 static int __init css_bus_init(void)
1178 {
1179         int ret, i;
1180
1181         ret = chsc_init();
1182         if (ret)
1183                 return ret;
1184
1185         chsc_determine_css_characteristics();
1186         /* Try to enable MSS. */
1187         ret = chsc_enable_facility(CHSC_SDA_OC_MSS);
1188         if (ret)
1189                 max_ssid = 0;
1190         else /* Success. */
1191                 max_ssid = __MAX_SSID;
1192
1193         ret = slow_subchannel_init();
1194         if (ret)
1195                 goto out;
1196
1197         ret = crw_register_handler(CRW_RSC_SCH, css_process_crw);
1198         if (ret)
1199                 goto out;
1200
1201         if ((ret = bus_register(&css_bus_type)))
1202                 goto out;
1203
1204         /* Setup css structure. */
1205         for (i = 0; i <= MAX_CSS_IDX; i++) {
1206                 ret = setup_css(i);
1207                 if (ret)
1208                         goto out_unregister;
1209         }
1210         ret = register_reboot_notifier(&css_reboot_notifier);
1211         if (ret)
1212                 goto out_unregister;
1213         ret = cio_dma_pool_init();
1214         if (ret)
1215                 goto out_unregister_rn;
1216         airq_init();
1217         css_init_done = 1;
1218
1219         /* Enable default isc for I/O subchannels. */
1220         isc_register(IO_SCH_ISC);
1221
1222         return 0;
1223 out_unregister_rn:
1224         unregister_reboot_notifier(&css_reboot_notifier);
1225 out_unregister:
1226         while (i-- > 0) {
1227                 struct channel_subsystem *css = channel_subsystems[i];
1228                 device_unregister(&css->pseudo_subchannel->dev);
1229                 device_unregister(&css->device);
1230         }
1231         bus_unregister(&css_bus_type);
1232 out:
1233         crw_unregister_handler(CRW_RSC_SCH);
1234         idset_free(slow_subchannel_set);
1235         chsc_init_cleanup();
1236         pr_alert("The CSS device driver initialization failed with "
1237                  "errno=%d\n", ret);
1238         return ret;
1239 }
1240
1241 static void __init css_bus_cleanup(void)
1242 {
1243         struct channel_subsystem *css;
1244
1245         for_each_css(css) {
1246                 device_unregister(&css->pseudo_subchannel->dev);
1247                 device_unregister(&css->device);
1248         }
1249         bus_unregister(&css_bus_type);
1250         crw_unregister_handler(CRW_RSC_SCH);
1251         idset_free(slow_subchannel_set);
1252         chsc_init_cleanup();
1253         isc_unregister(IO_SCH_ISC);
1254 }
1255
1256 static int __init channel_subsystem_init(void)
1257 {
1258         int ret;
1259
1260         ret = css_bus_init();
1261         if (ret)
1262                 return ret;
1263         cio_work_q = create_singlethread_workqueue("cio");
1264         if (!cio_work_q) {
1265                 ret = -ENOMEM;
1266                 goto out_bus;
1267         }
1268         ret = io_subchannel_init();
1269         if (ret)
1270                 goto out_wq;
1271
1272         /* Register subchannels which are already in use. */
1273         cio_register_early_subchannels();
1274         /* Start initial subchannel evaluation. */
1275         css_schedule_eval_all();
1276
1277         return ret;
1278 out_wq:
1279         destroy_workqueue(cio_work_q);
1280 out_bus:
1281         css_bus_cleanup();
1282         return ret;
1283 }
1284 subsys_initcall(channel_subsystem_init);
1285
1286 static int css_settle(struct device_driver *drv, void *unused)
1287 {
1288         struct css_driver *cssdrv = to_cssdriver(drv);
1289
1290         if (cssdrv->settle)
1291                 return cssdrv->settle();
1292         return 0;
1293 }
1294
1295 int css_complete_work(void)
1296 {
1297         int ret;
1298
1299         /* Wait for the evaluation of subchannels to finish. */
1300         ret = wait_event_interruptible(css_eval_wq,
1301                                        atomic_read(&css_eval_scheduled) == 0);
1302         if (ret)
1303                 return -EINTR;
1304         flush_workqueue(cio_work_q);
1305         /* Wait for the subchannel type specific initialization to finish */
1306         return bus_for_each_drv(&css_bus_type, NULL, NULL, css_settle);
1307 }
1308
1309
1310 /*
1311  * Wait for the initialization of devices to finish, to make sure we are
1312  * done with our setup if the search for the root device starts.
1313  */
1314 static int __init channel_subsystem_init_sync(void)
1315 {
1316         css_complete_work();
1317         return 0;
1318 }
1319 subsys_initcall_sync(channel_subsystem_init_sync);
1320
1321 #ifdef CONFIG_PROC_FS
1322 static ssize_t cio_settle_write(struct file *file, const char __user *buf,
1323                                 size_t count, loff_t *ppos)
1324 {
1325         int ret;
1326
1327         /* Handle pending CRW's. */
1328         crw_wait_for_channel_report();
1329         ret = css_complete_work();
1330
1331         return ret ? ret : count;
1332 }
1333
1334 static const struct proc_ops cio_settle_proc_ops = {
1335         .proc_open      = nonseekable_open,
1336         .proc_write     = cio_settle_write,
1337         .proc_lseek     = no_llseek,
1338 };
1339
1340 static int __init cio_settle_init(void)
1341 {
1342         struct proc_dir_entry *entry;
1343
1344         entry = proc_create("cio_settle", S_IWUSR, NULL, &cio_settle_proc_ops);
1345         if (!entry)
1346                 return -ENOMEM;
1347         return 0;
1348 }
1349 device_initcall(cio_settle_init);
1350 #endif /*CONFIG_PROC_FS*/
1351
1352 int sch_is_pseudo_sch(struct subchannel *sch)
1353 {
1354         if (!sch->dev.parent)
1355                 return 0;
1356         return sch == to_css(sch->dev.parent)->pseudo_subchannel;
1357 }
1358
1359 static int css_bus_match(struct device *dev, struct device_driver *drv)
1360 {
1361         struct subchannel *sch = to_subchannel(dev);
1362         struct css_driver *driver = to_cssdriver(drv);
1363         struct css_device_id *id;
1364
1365         /* When driver_override is set, only bind to the matching driver */
1366         if (sch->driver_override && strcmp(sch->driver_override, drv->name))
1367                 return 0;
1368
1369         for (id = driver->subchannel_type; id->match_flags; id++) {
1370                 if (sch->st == id->type)
1371                         return 1;
1372         }
1373
1374         return 0;
1375 }
1376
1377 static int css_probe(struct device *dev)
1378 {
1379         struct subchannel *sch;
1380         int ret;
1381
1382         sch = to_subchannel(dev);
1383         sch->driver = to_cssdriver(dev->driver);
1384         ret = sch->driver->probe ? sch->driver->probe(sch) : 0;
1385         if (ret)
1386                 sch->driver = NULL;
1387         return ret;
1388 }
1389
1390 static void css_remove(struct device *dev)
1391 {
1392         struct subchannel *sch;
1393
1394         sch = to_subchannel(dev);
1395         if (sch->driver->remove)
1396                 sch->driver->remove(sch);
1397         sch->driver = NULL;
1398 }
1399
1400 static void css_shutdown(struct device *dev)
1401 {
1402         struct subchannel *sch;
1403
1404         sch = to_subchannel(dev);
1405         if (sch->driver && sch->driver->shutdown)
1406                 sch->driver->shutdown(sch);
1407 }
1408
1409 static int css_uevent(struct device *dev, struct kobj_uevent_env *env)
1410 {
1411         struct subchannel *sch = to_subchannel(dev);
1412         int ret;
1413
1414         ret = add_uevent_var(env, "ST=%01X", sch->st);
1415         if (ret)
1416                 return ret;
1417         ret = add_uevent_var(env, "MODALIAS=css:t%01X", sch->st);
1418         return ret;
1419 }
1420
1421 static struct bus_type css_bus_type = {
1422         .name     = "css",
1423         .match    = css_bus_match,
1424         .probe    = css_probe,
1425         .remove   = css_remove,
1426         .shutdown = css_shutdown,
1427         .uevent   = css_uevent,
1428 };
1429
1430 /**
1431  * css_driver_register - register a css driver
1432  * @cdrv: css driver to register
1433  *
1434  * This is mainly a wrapper around driver_register that sets name
1435  * and bus_type in the embedded struct device_driver correctly.
1436  */
1437 int css_driver_register(struct css_driver *cdrv)
1438 {
1439         cdrv->drv.bus = &css_bus_type;
1440         return driver_register(&cdrv->drv);
1441 }
1442 EXPORT_SYMBOL_GPL(css_driver_register);
1443
1444 /**
1445  * css_driver_unregister - unregister a css driver
1446  * @cdrv: css driver to unregister
1447  *
1448  * This is a wrapper around driver_unregister.
1449  */
1450 void css_driver_unregister(struct css_driver *cdrv)
1451 {
1452         driver_unregister(&cdrv->drv);
1453 }
1454 EXPORT_SYMBOL_GPL(css_driver_unregister);