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/suspend.h>
  22 #include <linux/proc_fs.h>
  23 #include <linux/genalloc.h>
  24 #include <linux/dma-mapping.h>
  25 #include <asm/isc.h>
  26 #include <asm/crw.h>
  27
  28 #include "css.h"
  29 #include "cio.h"
  30 #include "blacklist.h"
  31 #include "cio_debug.h"
  32 #include "ioasm.h"
  33 #include "chsc.h"
  34 #include "device.h"
  35 #include "idset.h"
  36 #include "chp.h"
  37
  38 int css_init_done = 0;
  39 int max_ssid;
  40
  41 #define MAX_CSS_IDX 0
  42 struct channel_subsystem *channel_subsystems[MAX_CSS_IDX + 1];
  43 static struct bus_type css_bus_type;
  44
  45 int
  46 for_each_subchannel(int(*fn)(struct subchannel_id, void *), void *data)
  47 {
  48         struct subchannel_id schid;
  49         int ret;
  50
  51         init_subchannel_id(&schid);
  52         do {
  53                 do {
  54                         ret = fn(schid, data);
  55                         if (ret)
  56                                 break;
  57                 } while (schid.sch_no++ < __MAX_SUBCHANNEL);
  58                 schid.sch_no = 0;
  59         } while (schid.ssid++ < max_ssid);
  60         return ret;
  61 }
  62
  63 struct cb_data {
  64         void *data;
  65         struct idset *set;
  66         int (*fn_known_sch)(struct subchannel *, void *);
  67         int (*fn_unknown_sch)(struct subchannel_id, void *);
  68 };
  69
  70 static int call_fn_known_sch(struct device *dev, void *data)
  71 {
  72         struct subchannel *sch = to_subchannel(dev);
  73         struct cb_data *cb = data;
  74         int rc = 0;
  75
  76         if (cb->set)
  77                 idset_sch_del(cb->set, sch->schid);
  78         if (cb->fn_known_sch)
  79                 rc = cb->fn_known_sch(sch, cb->data);
  80         return rc;
  81 }
  82
  83 static int call_fn_unknown_sch(struct subchannel_id schid, void *data)
  84 {
  85         struct cb_data *cb = data;
  86         int rc = 0;
  87
  88         if (idset_sch_contains(cb->set, schid))
  89                 rc = cb->fn_unknown_sch(schid, cb->data);
  90         return rc;
  91 }
  92
  93 static int call_fn_all_sch(struct subchannel_id schid, void *data)
  94 {
  95         struct cb_data *cb = data;
  96         struct subchannel *sch;
  97         int rc = 0;
  98
  99         sch = get_subchannel_by_schid(schid);
 100         if (sch) {
 101                 if (cb->fn_known_sch)
 102                         rc = cb->fn_known_sch(sch, cb->data);
 103                 put_device(&sch->dev);
 104         } else {
 105                 if (cb->fn_unknown_sch)
 106                         rc = cb->fn_unknown_sch(schid, cb->data);
 107         }
 108
 109         return rc;
 110 }
 111
 112 int for_each_subchannel_staged(int (*fn_known)(struct subchannel *, void *),
 113                                int (*fn_unknown)(struct subchannel_id,
 114                                void *), void *data)
 115 {
 116         struct cb_data cb;
 117         int rc;
 118
 119         cb.data = data;
 120         cb.fn_known_sch = fn_known;
 121         cb.fn_unknown_sch = fn_unknown;
 122
 123         if (fn_known && !fn_unknown) {
 124                 /* Skip idset allocation in case of known-only loop. */
 125                 cb.set = NULL;
 126                 return bus_for_each_dev(&css_bus_type, NULL, &cb,
 127                                         call_fn_known_sch);
 128         }
 129
 130         cb.set = idset_sch_new();
 131         if (!cb.set)
 132                 /* fall back to brute force scanning in case of oom */
 133                 return for_each_subchannel(call_fn_all_sch, &cb);
 134
 135         idset_fill(cb.set);
 136
 137         /* Process registered subchannels. */
 138         rc = bus_for_each_dev(&css_bus_type, NULL, &cb, call_fn_known_sch);
 139         if (rc)
 140                 goto out;
 141         /* Process unregistered subchannels. */
 142         if (fn_unknown)
 143                 rc = for_each_subchannel(call_fn_unknown_sch, &cb);
 144 out:
 145         idset_free(cb.set);
 146
 147         return rc;
 148 }
 149
 150 static void css_sch_todo(struct work_struct *work);
 151
 152 static int css_sch_create_locks(struct subchannel *sch)
 153 {
 154         sch->lock = kmalloc(sizeof(*sch->lock), GFP_KERNEL);
 155         if (!sch->lock)
 156                 return -ENOMEM;
 157
 158         spin_lock_init(sch->lock);
 159         mutex_init(&sch->reg_mutex);
 160
 161         return 0;
 162 }
 163
 164 static void css_subchannel_release(struct device *dev)
 165 {
 166         struct subchannel *sch = to_subchannel(dev);
 167
 168         sch->config.intparm = 0;
 169         cio_commit_config(sch);
 170         kfree(sch->driver_override);
 171         kfree(sch->lock);
 172         kfree(sch);
 173 }
 174
 175 static int css_validate_subchannel(struct subchannel_id schid,
 176                                    struct schib *schib)
 177 {
 178         int err;
 179
 180         switch (schib->pmcw.st) {
 181         case SUBCHANNEL_TYPE_IO:
 182         case SUBCHANNEL_TYPE_MSG:
 183                 if (!css_sch_is_valid(schib))
 184                         err = -ENODEV;
 185                 else if (is_blacklisted(schid.ssid, schib->pmcw.dev)) {
 186                         CIO_MSG_EVENT(6, "Blacklisted device detected "
 187                                       "at devno %04X, subchannel set %x\n",
 188                                       schib->pmcw.dev, schid.ssid);
 189                         err = -ENODEV;
 190                 } else
 191                         err = 0;
 192                 break;
 193         default:
 194                 err = 0;
 195         }
 196         if (err)
 197                 goto out;
 198
 199         CIO_MSG_EVENT(4, "Subchannel 0.%x.%04x reports subchannel type %04X\n",
 200                       schid.ssid, schid.sch_no, schib->pmcw.st);
 201 out:
 202         return err;
 203 }
 204
 205 struct subchannel *css_alloc_subchannel(struct subchannel_id schid,
 206                                         struct schib *schib)
 207 {
 208         struct subchannel *sch;
 209         int ret;
 210
 211         ret = css_validate_subchannel(schid, schib);
 212         if (ret < 0)
 213                 return ERR_PTR(ret);
 214
 215         sch = kzalloc(sizeof(*sch), GFP_KERNEL | GFP_DMA);
 216         if (!sch)
 217                 return ERR_PTR(-ENOMEM);
 218
 219         sch->schid = schid;
 220         sch->schib = *schib;
 221         sch->st = schib->pmcw.st;
 222
 223         ret = css_sch_create_locks(sch);
 224         if (ret)
 225                 goto err;
 226
 227         INIT_WORK(&sch->todo_work, css_sch_todo);
 228         sch->dev.release = &css_subchannel_release;
 229         device_initialize(&sch->dev);
 230         /*
 231          * The physical addresses of some the dma structures that can
 232          * belong to a subchannel need to fit 31 bit width (e.g. ccw).
 233          */
 234         sch->dev.coherent_dma_mask = DMA_BIT_MASK(31);
 235         /*
 236          * But we don't have such restrictions imposed on the stuff that
 237          * is handled by the streaming API.
 238          */
 239         sch->dma_mask = DMA_BIT_MASK(64);
 240         sch->dev.dma_mask = &sch->dma_mask;
 241         return sch;
 242
 243 err:
 244         kfree(sch);
 245         return ERR_PTR(ret);
 246 }
 247
 248 static int css_sch_device_register(struct subchannel *sch)
 249 {
 250         int ret;
 251
 252         mutex_lock(&sch->reg_mutex);
 253         dev_set_name(&sch->dev, "0.%x.%04x", sch->schid.ssid,
 254                      sch->schid.sch_no);
 255         ret = device_add(&sch->dev);
 256         mutex_unlock(&sch->reg_mutex);
 257         return ret;
 258 }
 259
 260 /**
 261  * css_sch_device_unregister - unregister a subchannel
 262  * @sch: subchannel to be unregistered
 263  */
 264 void css_sch_device_unregister(struct subchannel *sch)
 265 {
 266         mutex_lock(&sch->reg_mutex);
 267         if (device_is_registered(&sch->dev))
 268                 device_unregister(&sch->dev);
 269         mutex_unlock(&sch->reg_mutex);
 270 }
 271 EXPORT_SYMBOL_GPL(css_sch_device_unregister);
 272
 273 static void ssd_from_pmcw(struct chsc_ssd_info *ssd, struct pmcw *pmcw)
 274 {
 275         int i;
 276         int mask;
 277
 278         memset(ssd, 0, sizeof(struct chsc_ssd_info));
 279         ssd->path_mask = pmcw->pim;
 280         for (i = 0; i < 8; i++) {
 281                 mask = 0x80 >> i;
 282                 if (pmcw->pim & mask) {
 283                         chp_id_init(&ssd->chpid[i]);
 284                         ssd->chpid[i].id = pmcw->chpid[i];
 285                 }
 286         }
 287 }
 288
 289 static void ssd_register_chpids(struct chsc_ssd_info *ssd)
 290 {
 291         int i;
 292         int mask;
 293
 294         for (i = 0; i < 8; i++) {
 295                 mask = 0x80 >> i;
 296                 if (ssd->path_mask & mask)
 297                         chp_new(ssd->chpid[i]);
 298         }
 299 }
 300
 301 void css_update_ssd_info(struct subchannel *sch)
 302 {
 303         int ret;
 304
 305         ret = chsc_get_ssd_info(sch->schid, &sch->ssd_info);
 306         if (ret)
 307                 ssd_from_pmcw(&sch->ssd_info, &sch->schib.pmcw);
 308
 309         ssd_register_chpids(&sch->ssd_info);
 310 }
 311
 312 static ssize_t type_show(struct device *dev, struct device_attribute *attr,
 313                          char *buf)
 314 {
 315         struct subchannel *sch = to_subchannel(dev);
 316
 317         return sprintf(buf, "%01x\n", sch->st);
 318 }
 319
 320 static DEVICE_ATTR_RO(type);
 321
 322 static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
 323                              char *buf)
 324 {
 325         struct subchannel *sch = to_subchannel(dev);
 326
 327         return sprintf(buf, "css:t%01X\n", sch->st);
 328 }
 329
 330 static DEVICE_ATTR_RO(modalias);
 331
 332 static ssize_t driver_override_store(struct device *dev,
 333                                      struct device_attribute *attr,
 334                                      const char *buf, size_t count)
 335 {
 336         struct subchannel *sch = to_subchannel(dev);
 337         char *driver_override, *old, *cp;
 338
 339         /* We need to keep extra room for a newline */
 340         if (count >= (PAGE_SIZE - 1))
 341                 return -EINVAL;
 342
 343         driver_override = kstrndup(buf, count, GFP_KERNEL);
 344         if (!driver_override)
 345                 return -ENOMEM;
 346
 347         cp = strchr(driver_override, '\n');
 348         if (cp)
 349                 *cp = '\0';
 350
 351         device_lock(dev);
 352         old = sch->driver_override;
 353         if (strlen(driver_override)) {
 354                 sch->driver_override = driver_override;
 355         } else {
 356                 kfree(driver_override);
 357                 sch->driver_override = NULL;
 358         }
 359         device_unlock(dev);
 360
 361         kfree(old);
 362
 363         return count;
 364 }
 365
 366 static ssize_t driver_override_show(struct device *dev,
 367                                     struct device_attribute *attr, char *buf)
 368 {
 369         struct subchannel *sch = to_subchannel(dev);
 370         ssize_t len;
 371
 372         device_lock(dev);
 373         len = snprintf(buf, PAGE_SIZE, "%s\n", sch->driver_override);
 374         device_unlock(dev);
 375         return len;
 376 }
 377 static DEVICE_ATTR_RW(driver_override);
 378
 379 static struct attribute *subch_attrs[] = {
 380         &dev_attr_type.attr,
 381         &dev_attr_modalias.attr,
 382         &dev_attr_driver_override.attr,
 383         NULL,
 384 };
 385
 386 static struct attribute_group subch_attr_group = {
 387         .attrs = subch_attrs,
 388 };
 389
 390 static const struct attribute_group *default_subch_attr_groups[] = {
 391         &subch_attr_group,
 392         NULL,
 393 };
 394
 395 static ssize_t chpids_show(struct device *dev,
 396                            struct device_attribute *attr,
 397                            char *buf)
 398 {
 399         struct subchannel *sch = to_subchannel(dev);
 400         struct chsc_ssd_info *ssd = &sch->ssd_info;
 401         ssize_t ret = 0;
 402         int mask;
 403         int chp;
 404
 405         for (chp = 0; chp < 8; chp++) {
 406                 mask = 0x80 >> chp;
 407                 if (ssd->path_mask & mask)
 408                         ret += sprintf(buf + ret, "%02x ", ssd->chpid[chp].id);
 409                 else
 410                         ret += sprintf(buf + ret, "00 ");
 411         }
 412         ret += sprintf(buf + ret, "\n");
 413         return ret;
 414 }
 415 static DEVICE_ATTR_RO(chpids);
 416
 417 static ssize_t pimpampom_show(struct device *dev,
 418                               struct device_attribute *attr,
 419                               char *buf)
 420 {
 421         struct subchannel *sch = to_subchannel(dev);
 422         struct pmcw *pmcw = &sch->schib.pmcw;
 423
 424         return sprintf(buf, "%02x %02x %02x\n",
 425                        pmcw->pim, pmcw->pam, pmcw->pom);
 426 }
 427 static DEVICE_ATTR_RO(pimpampom);
 428
 429 static struct attribute *io_subchannel_type_attrs[] = {
 430         &dev_attr_chpids.attr,
 431         &dev_attr_pimpampom.attr,
 432         NULL,
 433 };
 434 ATTRIBUTE_GROUPS(io_subchannel_type);
 435
 436 static const struct device_type io_subchannel_type = {
 437         .groups = io_subchannel_type_groups,
 438 };
 439
 440 int css_register_subchannel(struct subchannel *sch)
 441 {
 442         int ret;
 443
 444         /* Initialize the subchannel structure */
 445         sch->dev.parent = &channel_subsystems[0]->device;
 446         sch->dev.bus = &css_bus_type;
 447         sch->dev.groups = default_subch_attr_groups;
 448
 449         if (sch->st == SUBCHANNEL_TYPE_IO)
 450                 sch->dev.type = &io_subchannel_type;
 451
 452         /*
 453          * We don't want to generate uevents for I/O subchannels that don't
 454          * have a working ccw device behind them since they will be
 455          * unregistered before they can be used anyway, so we delay the add
 456          * uevent until after device recognition was successful.
 457          * Note that we suppress the uevent for all subchannel types;
 458          * the subchannel driver can decide itself when it wants to inform
 459          * userspace of its existence.
 460          */
 461         dev_set_uevent_suppress(&sch->dev, 1);
 462         css_update_ssd_info(sch);
 463         /* make it known to the system */
 464         ret = css_sch_device_register(sch);
 465         if (ret) {
 466                 CIO_MSG_EVENT(0, "Could not register sch 0.%x.%04x: %d\n",
 467                               sch->schid.ssid, sch->schid.sch_no, ret);
 468                 return ret;
 469         }
 470         if (!sch->driver) {
 471                 /*
 472                  * No driver matched. Generate the uevent now so that
 473                  * a fitting driver module may be loaded based on the
 474                  * modalias.
 475                  */
 476                 dev_set_uevent_suppress(&sch->dev, 0);
 477                 kobject_uevent(&sch->dev.kobj, KOBJ_ADD);
 478         }
 479         return ret;
 480 }
 481
 482 static int css_probe_device(struct subchannel_id schid, struct schib *schib)
 483 {
 484         struct subchannel *sch;
 485         int ret;
 486
 487         sch = css_alloc_subchannel(schid, schib);
 488         if (IS_ERR(sch))
 489                 return PTR_ERR(sch);
 490
 491         ret = css_register_subchannel(sch);
 492         if (ret)
 493                 put_device(&sch->dev);
 494
 495         return ret;
 496 }
 497
 498 static int
 499 check_subchannel(struct device *dev, const void *data)
 500 {
 501         struct subchannel *sch;
 502         struct subchannel_id *schid = (void *)data;
 503
 504         sch = to_subchannel(dev);
 505         return schid_equal(&sch->schid, schid);
 506 }
 507
 508 struct subchannel *
 509 get_subchannel_by_schid(struct subchannel_id schid)
 510 {
 511         struct device *dev;
 512
 513         dev = bus_find_device(&css_bus_type, NULL,
 514                               &schid, check_subchannel);
 515
 516         return dev ? to_subchannel(dev) : NULL;
 517 }
 518
 519 /**
 520  * css_sch_is_valid() - check if a subchannel is valid
 521  * @schib: subchannel information block for the subchannel
 522  */
 523 int css_sch_is_valid(struct schib *schib)
 524 {
 525         if ((schib->pmcw.st == SUBCHANNEL_TYPE_IO) && !schib->pmcw.dnv)
 526                 return 0;
 527         if ((schib->pmcw.st == SUBCHANNEL_TYPE_MSG) && !schib->pmcw.w)
 528                 return 0;
 529         return 1;
 530 }
 531 EXPORT_SYMBOL_GPL(css_sch_is_valid);
 532
 533 static int css_evaluate_new_subchannel(struct subchannel_id schid, int slow)
 534 {
 535         struct schib schib;
 536         int ccode;
 537
 538         if (!slow) {
 539                 /* Will be done on the slow path. */
 540                 return -EAGAIN;
 541         }
 542         /*
 543          * The first subchannel that is not-operational (ccode==3)
 544          * indicates that there aren't any more devices available.
 545          * If stsch gets an exception, it means the current subchannel set
 546          * is not valid.
 547          */
 548         ccode = stsch(schid, &schib);
 549         if (ccode)
 550                 return (ccode == 3) ? -ENXIO : ccode;
 551
 552         return css_probe_device(schid, &schib);
 553 }
 554
 555 static int css_evaluate_known_subchannel(struct subchannel *sch, int slow)
 556 {
 557         int ret = 0;
 558
 559         if (sch->driver) {
 560                 if (sch->driver->sch_event)
 561                         ret = sch->driver->sch_event(sch, slow);
 562                 else
 563                         dev_dbg(&sch->dev,
 564                                 "Got subchannel machine check but "
 565                                 "no sch_event handler provided.\n");
 566         }
 567         if (ret != 0 && ret != -EAGAIN) {
 568                 CIO_MSG_EVENT(2, "eval: sch 0.%x.%04x, rc=%d\n",
 569                               sch->schid.ssid, sch->schid.sch_no, ret);
 570         }
 571         return ret;
 572 }
 573
 574 static void css_evaluate_subchannel(struct subchannel_id schid, int slow)
 575 {
 576         struct subchannel *sch;
 577         int ret;
 578
 579         sch = get_subchannel_by_schid(schid);
 580         if (sch) {
 581                 ret = css_evaluate_known_subchannel(sch, slow);
 582                 put_device(&sch->dev);
 583         } else
 584                 ret = css_evaluate_new_subchannel(schid, slow);
 585         if (ret == -EAGAIN)
 586                 css_schedule_eval(schid);
 587 }
 588
 589 /**
 590  * css_sched_sch_todo - schedule a subchannel operation
 591  * @sch: subchannel
 592  * @todo: todo
 593  *
 594  * Schedule the operation identified by @todo to be performed on the slow path
 595  * workqueue. Do nothing if another operation with higher priority is already
 596  * scheduled. Needs to be called with subchannel lock held.
 597  */
 598 void css_sched_sch_todo(struct subchannel *sch, enum sch_todo todo)
 599 {
 600         CIO_MSG_EVENT(4, "sch_todo: sched sch=0.%x.%04x todo=%d\n",
 601                       sch->schid.ssid, sch->schid.sch_no, todo);
 602         if (sch->todo >= todo)
 603                 return;
 604         /* Get workqueue ref. */
 605         if (!get_device(&sch->dev))
 606                 return;
 607         sch->todo = todo;
 608         if (!queue_work(cio_work_q, &sch->todo_work)) {
 609                 /* Already queued, release workqueue ref. */
 610                 put_device(&sch->dev);
 611         }
 612 }
 613 EXPORT_SYMBOL_GPL(css_sched_sch_todo);
 614
 615 static void css_sch_todo(struct work_struct *work)
 616 {
 617         struct subchannel *sch;
 618         enum sch_todo todo;
 619         int ret;
 620
 621         sch = container_of(work, struct subchannel, todo_work);
 622         /* Find out todo. */
 623         spin_lock_irq(sch->lock);
 624         todo = sch->todo;
 625         CIO_MSG_EVENT(4, "sch_todo: sch=0.%x.%04x, todo=%d\n", sch->schid.ssid,
 626                       sch->schid.sch_no, todo);
 627         sch->todo = SCH_TODO_NOTHING;
 628         spin_unlock_irq(sch->lock);
 629         /* Perform todo. */
 630         switch (todo) {
 631         case SCH_TODO_NOTHING:
 632                 break;
 633         case SCH_TODO_EVAL:
 634                 ret = css_evaluate_known_subchannel(sch, 1);
 635                 if (ret == -EAGAIN) {
 636                         spin_lock_irq(sch->lock);
 637                         css_sched_sch_todo(sch, todo);
 638                         spin_unlock_irq(sch->lock);
 639                 }
 640                 break;
 641         case SCH_TODO_UNREG:
 642                 css_sch_device_unregister(sch);
 643                 break;
 644         }
 645         /* Release workqueue ref. */
 646         put_device(&sch->dev);
 647 }
 648
 649 static struct idset *slow_subchannel_set;
 650 static spinlock_t slow_subchannel_lock;
 651 static wait_queue_head_t css_eval_wq;
 652 static atomic_t css_eval_scheduled;
 653
 654 static int __init slow_subchannel_init(void)
 655 {
 656         spin_lock_init(&slow_subchannel_lock);
 657         atomic_set(&css_eval_scheduled, 0);
 658         init_waitqueue_head(&css_eval_wq);
 659         slow_subchannel_set = idset_sch_new();
 660         if (!slow_subchannel_set) {
 661                 CIO_MSG_EVENT(0, "could not allocate slow subchannel set\n");
 662                 return -ENOMEM;
 663         }
 664         return 0;
 665 }
 666
 667 static int slow_eval_known_fn(struct subchannel *sch, void *data)
 668 {
 669         int eval;
 670         int rc;
 671
 672         spin_lock_irq(&slow_subchannel_lock);
 673         eval = idset_sch_contains(slow_subchannel_set, sch->schid);
 674         idset_sch_del(slow_subchannel_set, sch->schid);
 675         spin_unlock_irq(&slow_subchannel_lock);
 676         if (eval) {
 677                 rc = css_evaluate_known_subchannel(sch, 1);
 678                 if (rc == -EAGAIN)
 679                         css_schedule_eval(sch->schid);
 680         }
 681         return 0;
 682 }
 683
 684 static int slow_eval_unknown_fn(struct subchannel_id schid, void *data)
 685 {
 686         int eval;
 687         int rc = 0;
 688
 689         spin_lock_irq(&slow_subchannel_lock);
 690         eval = idset_sch_contains(slow_subchannel_set, schid);
 691         idset_sch_del(slow_subchannel_set, schid);
 692         spin_unlock_irq(&slow_subchannel_lock);
 693         if (eval) {
 694                 rc = css_evaluate_new_subchannel(schid, 1);
 695                 switch (rc) {
 696                 case -EAGAIN:
 697                         css_schedule_eval(schid);
 698                         rc = 0;
 699                         break;
 700                 case -ENXIO:
 701                 case -ENOMEM:
 702                 case -EIO:
 703                         /* These should abort looping */
 704                         spin_lock_irq(&slow_subchannel_lock);
 705                         idset_sch_del_subseq(slow_subchannel_set, schid);
 706                         spin_unlock_irq(&slow_subchannel_lock);
 707                         break;
 708                 default:
 709                         rc = 0;
 710                 }
 711                 /* Allow scheduling here since the containing loop might
 712                  * take a while.  */
 713                 cond_resched();
 714         }
 715         return rc;
 716 }
 717
 718 static void css_slow_path_func(struct work_struct *unused)
 719 {
 720         unsigned long flags;
 721
 722         CIO_TRACE_EVENT(4, "slowpath");
 723         for_each_subchannel_staged(slow_eval_known_fn, slow_eval_unknown_fn,
 724                                    NULL);
 725         spin_lock_irqsave(&slow_subchannel_lock, flags);
 726         if (idset_is_empty(slow_subchannel_set)) {
 727                 atomic_set(&css_eval_scheduled, 0);
 728                 wake_up(&css_eval_wq);
 729         }
 730         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 731 }
 732
 733 static DECLARE_DELAYED_WORK(slow_path_work, css_slow_path_func);
 734 struct workqueue_struct *cio_work_q;
 735
 736 void css_schedule_eval(struct subchannel_id schid)
 737 {
 738         unsigned long flags;
 739
 740         spin_lock_irqsave(&slow_subchannel_lock, flags);
 741         idset_sch_add(slow_subchannel_set, schid);
 742         atomic_set(&css_eval_scheduled, 1);
 743         queue_delayed_work(cio_work_q, &slow_path_work, 0);
 744         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 745 }
 746
 747 void css_schedule_eval_all(void)
 748 {
 749         unsigned long flags;
 750
 751         spin_lock_irqsave(&slow_subchannel_lock, flags);
 752         idset_fill(slow_subchannel_set);
 753         atomic_set(&css_eval_scheduled, 1);
 754         queue_delayed_work(cio_work_q, &slow_path_work, 0);
 755         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 756 }
 757
 758 static int __unset_registered(struct device *dev, void *data)
 759 {
 760         struct idset *set = data;
 761         struct subchannel *sch = to_subchannel(dev);
 762
 763         idset_sch_del(set, sch->schid);
 764         return 0;
 765 }
 766
 767 void css_schedule_eval_all_unreg(unsigned long delay)
 768 {
 769         unsigned long flags;
 770         struct idset *unreg_set;
 771
 772         /* Find unregistered subchannels. */
 773         unreg_set = idset_sch_new();
 774         if (!unreg_set) {
 775                 /* Fallback. */
 776                 css_schedule_eval_all();
 777                 return;
 778         }
 779         idset_fill(unreg_set);
 780         bus_for_each_dev(&css_bus_type, NULL, unreg_set, __unset_registered);
 781         /* Apply to slow_subchannel_set. */
 782         spin_lock_irqsave(&slow_subchannel_lock, flags);
 783         idset_add_set(slow_subchannel_set, unreg_set);
 784         atomic_set(&css_eval_scheduled, 1);
 785         queue_delayed_work(cio_work_q, &slow_path_work, delay);
 786         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 787         idset_free(unreg_set);
 788 }
 789
 790 void css_wait_for_slow_path(void)
 791 {
 792         flush_workqueue(cio_work_q);
 793 }
 794
 795 /* Schedule reprobing of all unregistered subchannels. */
 796 void css_schedule_reprobe(void)
 797 {
 798         /* Schedule with a delay to allow merging of subsequent calls. */
 799         css_schedule_eval_all_unreg(1 * HZ);
 800 }
 801 EXPORT_SYMBOL_GPL(css_schedule_reprobe);
 802
 803 /*
 804  * Called from the machine check handler for subchannel report words.
 805  */
 806 static void css_process_crw(struct crw *crw0, struct crw *crw1, int overflow)
 807 {
 808         struct subchannel_id mchk_schid;
 809         struct subchannel *sch;
 810
 811         if (overflow) {
 812                 css_schedule_eval_all();
 813                 return;
 814         }
 815         CIO_CRW_EVENT(2, "CRW0 reports slct=%d, oflw=%d, "
 816                       "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
 817                       crw0->slct, crw0->oflw, crw0->chn, crw0->rsc, crw0->anc,
 818                       crw0->erc, crw0->rsid);
 819         if (crw1)
 820                 CIO_CRW_EVENT(2, "CRW1 reports slct=%d, oflw=%d, "
 821                               "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
 822                               crw1->slct, crw1->oflw, crw1->chn, crw1->rsc,
 823                               crw1->anc, crw1->erc, crw1->rsid);
 824         init_subchannel_id(&mchk_schid);
 825         mchk_schid.sch_no = crw0->rsid;
 826         if (crw1)
 827                 mchk_schid.ssid = (crw1->rsid >> 4) & 3;
 828
 829         if (crw0->erc == CRW_ERC_PMOD) {
 830                 sch = get_subchannel_by_schid(mchk_schid);
 831                 if (sch) {
 832                         css_update_ssd_info(sch);
 833                         put_device(&sch->dev);
 834                 }
 835         }
 836         /*
 837          * Since we are always presented with IPI in the CRW, we have to
 838          * use stsch() to find out if the subchannel in question has come
 839          * or gone.
 840          */
 841         css_evaluate_subchannel(mchk_schid, 0);
 842 }
 843
 844 static void __init
 845 css_generate_pgid(struct channel_subsystem *css, u32 tod_high)
 846 {
 847         struct cpuid cpu_id;
 848
 849         if (css_general_characteristics.mcss) {
 850                 css->global_pgid.pgid_high.ext_cssid.version = 0x80;
 851                 css->global_pgid.pgid_high.ext_cssid.cssid =
 852                         (css->cssid < 0) ? 0 : css->cssid;
 853         } else {
 854                 css->global_pgid.pgid_high.cpu_addr = stap();
 855         }
 856         get_cpu_id(&cpu_id);
 857         css->global_pgid.cpu_id = cpu_id.ident;
 858         css->global_pgid.cpu_model = cpu_id.machine;
 859         css->global_pgid.tod_high = tod_high;
 860 }
 861
 862 static void channel_subsystem_release(struct device *dev)
 863 {
 864         struct channel_subsystem *css = to_css(dev);
 865
 866         mutex_destroy(&css->mutex);
 867         kfree(css);
 868 }
 869
 870 static ssize_t real_cssid_show(struct device *dev, struct device_attribute *a,
 871                                char *buf)
 872 {
 873         struct channel_subsystem *css = to_css(dev);
 874
 875         if (css->cssid < 0)
 876                 return -EINVAL;
 877
 878         return sprintf(buf, "%x\n", css->cssid);
 879 }
 880 static DEVICE_ATTR_RO(real_cssid);
 881
 882 static ssize_t cm_enable_show(struct device *dev, struct device_attribute *a,
 883                               char *buf)
 884 {
 885         struct channel_subsystem *css = to_css(dev);
 886         int ret;
 887
 888         mutex_lock(&css->mutex);
 889         ret = sprintf(buf, "%x\n", css->cm_enabled);
 890         mutex_unlock(&css->mutex);
 891         return ret;
 892 }
 893
 894 static ssize_t cm_enable_store(struct device *dev, struct device_attribute *a,
 895                                const char *buf, size_t count)
 896 {
 897         struct channel_subsystem *css = to_css(dev);
 898         unsigned long val;
 899         int ret;
 900
 901         ret = kstrtoul(buf, 16, &val);
 902         if (ret)
 903                 return ret;
 904         mutex_lock(&css->mutex);
 905         switch (val) {
 906         case 0:
 907                 ret = css->cm_enabled ? chsc_secm(css, 0) : 0;
 908                 break;
 909         case 1:
 910                 ret = css->cm_enabled ? 0 : chsc_secm(css, 1);
 911                 break;
 912         default:
 913                 ret = -EINVAL;
 914         }
 915         mutex_unlock(&css->mutex);
 916         return ret < 0 ? ret : count;
 917 }
 918 static DEVICE_ATTR_RW(cm_enable);
 919
 920 static umode_t cm_enable_mode(struct kobject *kobj, struct attribute *attr,
 921                               int index)
 922 {
 923         return css_chsc_characteristics.secm ? attr->mode : 0;
 924 }
 925
 926 static struct attribute *cssdev_attrs[] = {
 927         &dev_attr_real_cssid.attr,
 928         NULL,
 929 };
 930
 931 static struct attribute_group cssdev_attr_group = {
 932         .attrs = cssdev_attrs,
 933 };
 934
 935 static struct attribute *cssdev_cm_attrs[] = {
 936         &dev_attr_cm_enable.attr,
 937         NULL,
 938 };
 939
 940 static struct attribute_group cssdev_cm_attr_group = {
 941         .attrs = cssdev_cm_attrs,
 942         .is_visible = cm_enable_mode,
 943 };
 944
 945 static const struct attribute_group *cssdev_attr_groups[] = {
 946         &cssdev_attr_group,
 947         &cssdev_cm_attr_group,
 948         NULL,
 949 };
 950
 951 static int __init setup_css(int nr)
 952 {
 953         struct channel_subsystem *css;
 954         int ret;
 955
 956         css = kzalloc(sizeof(*css), GFP_KERNEL);
 957         if (!css)
 958                 return -ENOMEM;
 959
 960         channel_subsystems[nr] = css;
 961         dev_set_name(&css->device, "css%x", nr);
 962         css->device.groups = cssdev_attr_groups;
 963         css->device.release = channel_subsystem_release;
 964         /*
 965          * We currently allocate notifier bits with this (using
 966          * css->device as the device argument with the DMA API)
 967          * and are fine with 64 bit addresses.
 968          */
 969         css->device.coherent_dma_mask = DMA_BIT_MASK(64);
 970         css->device.dma_mask = &css->device.coherent_dma_mask;
 971
 972         mutex_init(&css->mutex);
 973         css->cssid = chsc_get_cssid(nr);
 974         css_generate_pgid(css, (u32) (get_tod_clock() >> 32));
 975
 976         ret = device_register(&css->device);
 977         if (ret) {
 978                 put_device(&css->device);
 979                 goto out_err;
 980         }
 981
 982         css->pseudo_subchannel = kzalloc(sizeof(*css->pseudo_subchannel),
 983                                          GFP_KERNEL);
 984         if (!css->pseudo_subchannel) {
 985                 device_unregister(&css->device);
 986                 ret = -ENOMEM;
 987                 goto out_err;
 988         }
 989
 990         css->pseudo_subchannel->dev.parent = &css->device;
 991         css->pseudo_subchannel->dev.release = css_subchannel_release;
 992         mutex_init(&css->pseudo_subchannel->reg_mutex);
 993         ret = css_sch_create_locks(css->pseudo_subchannel);
 994         if (ret) {
 995                 kfree(css->pseudo_subchannel);
 996                 device_unregister(&css->device);
 997                 goto out_err;
 998         }
 999
1000         dev_set_name(&css->pseudo_subchannel->dev, "defunct");
1001         ret = device_register(&css->pseudo_subchannel->dev);
1002         if (ret) {
1003                 put_device(&css->pseudo_subchannel->dev);
1004                 device_unregister(&css->device);
1005                 goto out_err;
1006         }
1007
1008         return ret;
1009 out_err:
1010         channel_subsystems[nr] = NULL;
1011         return ret;
1012 }
1013
1014 static int css_reboot_event(struct notifier_block *this,
1015                             unsigned long event,
1016                             void *ptr)
1017 {
1018         struct channel_subsystem *css;
1019         int ret;
1020
1021         ret = NOTIFY_DONE;
1022         for_each_css(css) {
1023                 mutex_lock(&css->mutex);
1024                 if (css->cm_enabled)
1025                         if (chsc_secm(css, 0))
1026                                 ret = NOTIFY_BAD;
1027                 mutex_unlock(&css->mutex);
1028         }
1029
1030         return ret;
1031 }
1032
1033 static struct notifier_block css_reboot_notifier = {
1034         .notifier_call = css_reboot_event,
1035 };
1036
1037 /*
1038  * Since the css devices are neither on a bus nor have a class
1039  * nor have a special device type, we cannot stop/restart channel
1040  * path measurements via the normal suspend/resume callbacks, but have
1041  * to use notifiers.
1042  */
1043 static int css_power_event(struct notifier_block *this, unsigned long event,
1044                            void *ptr)
1045 {
1046         struct channel_subsystem *css;
1047         int ret;
1048
1049         switch (event) {
1050         case PM_HIBERNATION_PREPARE:
1051         case PM_SUSPEND_PREPARE:
1052                 ret = NOTIFY_DONE;
1053                 for_each_css(css) {
1054                         mutex_lock(&css->mutex);
1055                         if (!css->cm_enabled) {
1056                                 mutex_unlock(&css->mutex);
1057                                 continue;
1058                         }
1059                         ret = __chsc_do_secm(css, 0);
1060                         ret = notifier_from_errno(ret);
1061                         mutex_unlock(&css->mutex);
1062                 }
1063                 break;
1064         case PM_POST_HIBERNATION:
1065         case PM_POST_SUSPEND:
1066                 ret = NOTIFY_DONE;
1067                 for_each_css(css) {
1068                         mutex_lock(&css->mutex);
1069                         if (!css->cm_enabled) {
1070                                 mutex_unlock(&css->mutex);
1071                                 continue;
1072                         }
1073                         ret = __chsc_do_secm(css, 1);
1074                         ret = notifier_from_errno(ret);
1075                         mutex_unlock(&css->mutex);
1076                 }
1077                 /* search for subchannels, which appeared during hibernation */
1078                 css_schedule_reprobe();
1079                 break;
1080         default:
1081                 ret = NOTIFY_DONE;
1082         }
1083         return ret;
1084
1085 }
1086 static struct notifier_block css_power_notifier = {
1087         .notifier_call = css_power_event,
1088 };
1089
1090 #define  CIO_DMA_GFP (GFP_KERNEL | __GFP_ZERO)
1091 static struct gen_pool *cio_dma_pool;
1092
1093 /* Currently cio supports only a single css */
1094 struct device *cio_get_dma_css_dev(void)
1095 {
1096         return &channel_subsystems[0]->device;
1097 }
1098
1099 struct gen_pool *cio_gp_dma_create(struct device *dma_dev, int nr_pages)
1100 {
1101         struct gen_pool *gp_dma;
1102         void *cpu_addr;
1103         dma_addr_t dma_addr;
1104         int i;
1105
1106         gp_dma = gen_pool_create(3, -1);
1107         if (!gp_dma)
1108                 return NULL;
1109         for (i = 0; i < nr_pages; ++i) {
1110                 cpu_addr = dma_alloc_coherent(dma_dev, PAGE_SIZE, &dma_addr,
1111                                               CIO_DMA_GFP);
1112                 if (!cpu_addr)
1113                         return gp_dma;
1114                 gen_pool_add_virt(gp_dma, (unsigned long) cpu_addr,
1115                                   dma_addr, PAGE_SIZE, -1);
1116         }
1117         return gp_dma;
1118 }
1119
1120 static void __gp_dma_free_dma(struct gen_pool *pool,
1121                               struct gen_pool_chunk *chunk, void *data)
1122 {
1123         size_t chunk_size = chunk->end_addr - chunk->start_addr + 1;
1124
1125         dma_free_coherent((struct device *) data, chunk_size,
1126                          (void *) chunk->start_addr,
1127                          (dma_addr_t) chunk->phys_addr);
1128 }
1129
1130 void cio_gp_dma_destroy(struct gen_pool *gp_dma, struct device *dma_dev)
1131 {
1132         if (!gp_dma)
1133                 return;
1134         /* this is quite ugly but no better idea */
1135         gen_pool_for_each_chunk(gp_dma, __gp_dma_free_dma, dma_dev);
1136         gen_pool_destroy(gp_dma);
1137 }
1138
1139 static int cio_dma_pool_init(void)
1140 {
1141         /* No need to free up the resources: compiled in */
1142         cio_dma_pool = cio_gp_dma_create(cio_get_dma_css_dev(), 1);
1143         if (!cio_dma_pool)
1144                 return -ENOMEM;
1145         return 0;
1146 }
1147
1148 void *cio_gp_dma_zalloc(struct gen_pool *gp_dma, struct device *dma_dev,
1149                         size_t size)
1150 {
1151         dma_addr_t dma_addr;
1152         unsigned long addr;
1153         size_t chunk_size;
1154
1155         if (!gp_dma)
1156                 return NULL;
1157         addr = gen_pool_alloc(gp_dma, size);
1158         while (!addr) {
1159                 chunk_size = round_up(size, PAGE_SIZE);
1160                 addr = (unsigned long) dma_alloc_coherent(dma_dev,
1161                                          chunk_size, &dma_addr, CIO_DMA_GFP);
1162                 if (!addr)
1163                         return NULL;
1164                 gen_pool_add_virt(gp_dma, addr, dma_addr, chunk_size, -1);
1165                 addr = gen_pool_alloc(gp_dma, size);
1166         }
1167         return (void *) addr;
1168 }
1169
1170 void cio_gp_dma_free(struct gen_pool *gp_dma, void *cpu_addr, size_t size)
1171 {
1172         if (!cpu_addr)
1173                 return;
1174         memset(cpu_addr, 0, size);
1175         gen_pool_free(gp_dma, (unsigned long) cpu_addr, size);
1176 }
1177
1178 /*
1179  * Allocate dma memory from the css global pool. Intended for memory not
1180  * specific to any single device within the css. The allocated memory
1181  * is not guaranteed to be 31-bit addressable.
1182  *
1183  * Caution: Not suitable for early stuff like console.
1184  */
1185 void *cio_dma_zalloc(size_t size)
1186 {
1187         return cio_gp_dma_zalloc(cio_dma_pool, cio_get_dma_css_dev(), size);
1188 }
1189
1190 void cio_dma_free(void *cpu_addr, size_t size)
1191 {
1192         cio_gp_dma_free(cio_dma_pool, cpu_addr, size);
1193 }
1194
1195 /*
1196  * Now that the driver core is running, we can setup our channel subsystem.
1197  * The struct subchannel's are created during probing.
1198  */
1199 static int __init css_bus_init(void)
1200 {
1201         int ret, i;
1202
1203         ret = chsc_init();
1204         if (ret)
1205                 return ret;
1206
1207         chsc_determine_css_characteristics();
1208         /* Try to enable MSS. */
1209         ret = chsc_enable_facility(CHSC_SDA_OC_MSS);
1210         if (ret)
1211                 max_ssid = 0;
1212         else /* Success. */
1213                 max_ssid = __MAX_SSID;
1214
1215         ret = slow_subchannel_init();
1216         if (ret)
1217                 goto out;
1218
1219         ret = crw_register_handler(CRW_RSC_SCH, css_process_crw);
1220         if (ret)
1221                 goto out;
1222
1223         if ((ret = bus_register(&css_bus_type)))
1224                 goto out;
1225
1226         /* Setup css structure. */
1227         for (i = 0; i <= MAX_CSS_IDX; i++) {
1228                 ret = setup_css(i);
1229                 if (ret)
1230                         goto out_unregister;
1231         }
1232         ret = register_reboot_notifier(&css_reboot_notifier);
1233         if (ret)
1234                 goto out_unregister;
1235         ret = register_pm_notifier(&css_power_notifier);
1236         if (ret)
1237                 goto out_unregister_rn;
1238         ret = cio_dma_pool_init();
1239         if (ret)
1240                 goto out_unregister_pmn;
1241         airq_init();
1242         css_init_done = 1;
1243
1244         /* Enable default isc for I/O subchannels. */
1245         isc_register(IO_SCH_ISC);
1246
1247         return 0;
1248 out_unregister_pmn:
1249         unregister_pm_notifier(&css_power_notifier);
1250 out_unregister_rn:
1251         unregister_reboot_notifier(&css_reboot_notifier);
1252 out_unregister:
1253         while (i-- > 0) {
1254                 struct channel_subsystem *css = channel_subsystems[i];
1255                 device_unregister(&css->pseudo_subchannel->dev);
1256                 device_unregister(&css->device);
1257         }
1258         bus_unregister(&css_bus_type);
1259 out:
1260         crw_unregister_handler(CRW_RSC_SCH);
1261         idset_free(slow_subchannel_set);
1262         chsc_init_cleanup();
1263         pr_alert("The CSS device driver initialization failed with "
1264                  "errno=%d\n", ret);
1265         return ret;
1266 }
1267
1268 static void __init css_bus_cleanup(void)
1269 {
1270         struct channel_subsystem *css;
1271
1272         for_each_css(css) {
1273                 device_unregister(&css->pseudo_subchannel->dev);
1274                 device_unregister(&css->device);
1275         }
1276         bus_unregister(&css_bus_type);
1277         crw_unregister_handler(CRW_RSC_SCH);
1278         idset_free(slow_subchannel_set);
1279         chsc_init_cleanup();
1280         isc_unregister(IO_SCH_ISC);
1281 }
1282
1283 static int __init channel_subsystem_init(void)
1284 {
1285         int ret;
1286
1287         ret = css_bus_init();
1288         if (ret)
1289                 return ret;
1290         cio_work_q = create_singlethread_workqueue("cio");
1291         if (!cio_work_q) {
1292                 ret = -ENOMEM;
1293                 goto out_bus;
1294         }
1295         ret = io_subchannel_init();
1296         if (ret)
1297                 goto out_wq;
1298
1299         /* Register subchannels which are already in use. */
1300         cio_register_early_subchannels();
1301         /* Start initial subchannel evaluation. */
1302         css_schedule_eval_all();
1303
1304         return ret;
1305 out_wq:
1306         destroy_workqueue(cio_work_q);
1307 out_bus:
1308         css_bus_cleanup();
1309         return ret;
1310 }
1311 subsys_initcall(channel_subsystem_init);
1312
1313 static int css_settle(struct device_driver *drv, void *unused)
1314 {
1315         struct css_driver *cssdrv = to_cssdriver(drv);
1316
1317         if (cssdrv->settle)
1318                 return cssdrv->settle();
1319         return 0;
1320 }
1321
1322 int css_complete_work(void)
1323 {
1324         int ret;
1325
1326         /* Wait for the evaluation of subchannels to finish. */
1327         ret = wait_event_interruptible(css_eval_wq,
1328                                        atomic_read(&css_eval_scheduled) == 0);
1329         if (ret)
1330                 return -EINTR;
1331         flush_workqueue(cio_work_q);
1332         /* Wait for the subchannel type specific initialization to finish */
1333         return bus_for_each_drv(&css_bus_type, NULL, NULL, css_settle);
1334 }
1335
1336
1337 /*
1338  * Wait for the initialization of devices to finish, to make sure we are
1339  * done with our setup if the search for the root device starts.
1340  */
1341 static int __init channel_subsystem_init_sync(void)
1342 {
1343         css_complete_work();
1344         return 0;
1345 }
1346 subsys_initcall_sync(channel_subsystem_init_sync);
1347
1348 void channel_subsystem_reinit(void)
1349 {
1350         struct channel_path *chp;
1351         struct chp_id chpid;
1352
1353         chsc_enable_facility(CHSC_SDA_OC_MSS);
1354         chp_id_for_each(&chpid) {
1355                 chp = chpid_to_chp(chpid);
1356                 if (chp)
1357                         chp_update_desc(chp);
1358         }
1359         cmf_reactivate();
1360 }
1361
1362 #ifdef CONFIG_PROC_FS
1363 static ssize_t cio_settle_write(struct file *file, const char __user *buf,
1364                                 size_t count, loff_t *ppos)
1365 {
1366         int ret;
1367
1368         /* Handle pending CRW's. */
1369         crw_wait_for_channel_report();
1370         ret = css_complete_work();
1371
1372         return ret ? ret : count;
1373 }
1374
1375 static const struct proc_ops cio_settle_proc_ops = {
1376         .proc_open      = nonseekable_open,
1377         .proc_write     = cio_settle_write,
1378         .proc_lseek     = no_llseek,
1379 };
1380
1381 static int __init cio_settle_init(void)
1382 {
1383         struct proc_dir_entry *entry;
1384
1385         entry = proc_create("cio_settle", S_IWUSR, NULL, &cio_settle_proc_ops);
1386         if (!entry)
1387                 return -ENOMEM;
1388         return 0;
1389 }
1390 device_initcall(cio_settle_init);
1391 #endif /*CONFIG_PROC_FS*/
1392
1393 int sch_is_pseudo_sch(struct subchannel *sch)
1394 {
1395         if (!sch->dev.parent)
1396                 return 0;
1397         return sch == to_css(sch->dev.parent)->pseudo_subchannel;
1398 }
1399
1400 static int css_bus_match(struct device *dev, struct device_driver *drv)
1401 {
1402         struct subchannel *sch = to_subchannel(dev);
1403         struct css_driver *driver = to_cssdriver(drv);
1404         struct css_device_id *id;
1405
1406         /* When driver_override is set, only bind to the matching driver */
1407         if (sch->driver_override && strcmp(sch->driver_override, drv->name))
1408                 return 0;
1409
1410         for (id = driver->subchannel_type; id->match_flags; id++) {
1411                 if (sch->st == id->type)
1412                         return 1;
1413         }
1414
1415         return 0;
1416 }
1417
1418 static int css_probe(struct device *dev)
1419 {
1420         struct subchannel *sch;
1421         int ret;
1422
1423         sch = to_subchannel(dev);
1424         sch->driver = to_cssdriver(dev->driver);
1425         ret = sch->driver->probe ? sch->driver->probe(sch) : 0;
1426         if (ret)
1427                 sch->driver = NULL;
1428         return ret;
1429 }
1430
1431 static int css_remove(struct device *dev)
1432 {
1433         struct subchannel *sch;
1434         int ret;
1435
1436         sch = to_subchannel(dev);
1437         ret = sch->driver->remove ? sch->driver->remove(sch) : 0;
1438         sch->driver = NULL;
1439         return ret;
1440 }
1441
1442 static void css_shutdown(struct device *dev)
1443 {
1444         struct subchannel *sch;
1445
1446         sch = to_subchannel(dev);
1447         if (sch->driver && sch->driver->shutdown)
1448                 sch->driver->shutdown(sch);
1449 }
1450
1451 static int css_uevent(struct device *dev, struct kobj_uevent_env *env)
1452 {
1453         struct subchannel *sch = to_subchannel(dev);
1454         int ret;
1455
1456         ret = add_uevent_var(env, "ST=%01X", sch->st);
1457         if (ret)
1458                 return ret;
1459         ret = add_uevent_var(env, "MODALIAS=css:t%01X", sch->st);
1460         return ret;
1461 }
1462
1463 static int css_pm_prepare(struct device *dev)
1464 {
1465         struct subchannel *sch = to_subchannel(dev);
1466         struct css_driver *drv;
1467
1468         if (mutex_is_locked(&sch->reg_mutex))
1469                 return -EAGAIN;
1470         if (!sch->dev.driver)
1471                 return 0;
1472         drv = to_cssdriver(sch->dev.driver);
1473         /* Notify drivers that they may not register children. */
1474         return drv->prepare ? drv->prepare(sch) : 0;
1475 }
1476
1477 static void css_pm_complete(struct device *dev)
1478 {
1479         struct subchannel *sch = to_subchannel(dev);
1480         struct css_driver *drv;
1481
1482         if (!sch->dev.driver)
1483                 return;
1484         drv = to_cssdriver(sch->dev.driver);
1485         if (drv->complete)
1486                 drv->complete(sch);
1487 }
1488
1489 static int css_pm_freeze(struct device *dev)
1490 {
1491         struct subchannel *sch = to_subchannel(dev);
1492         struct css_driver *drv;
1493
1494         if (!sch->dev.driver)
1495                 return 0;
1496         drv = to_cssdriver(sch->dev.driver);
1497         return drv->freeze ? drv->freeze(sch) : 0;
1498 }
1499
1500 static int css_pm_thaw(struct device *dev)
1501 {
1502         struct subchannel *sch = to_subchannel(dev);
1503         struct css_driver *drv;
1504
1505         if (!sch->dev.driver)
1506                 return 0;
1507         drv = to_cssdriver(sch->dev.driver);
1508         return drv->thaw ? drv->thaw(sch) : 0;
1509 }
1510
1511 static int css_pm_restore(struct device *dev)
1512 {
1513         struct subchannel *sch = to_subchannel(dev);
1514         struct css_driver *drv;
1515
1516         css_update_ssd_info(sch);
1517         if (!sch->dev.driver)
1518                 return 0;
1519         drv = to_cssdriver(sch->dev.driver);
1520         return drv->restore ? drv->restore(sch) : 0;
1521 }
1522
1523 static const struct dev_pm_ops css_pm_ops = {
1524         .prepare = css_pm_prepare,
1525         .complete = css_pm_complete,
1526         .freeze = css_pm_freeze,
1527         .thaw = css_pm_thaw,
1528         .restore = css_pm_restore,
1529 };
1530
1531 static struct bus_type css_bus_type = {
1532         .name     = "css",
1533         .match    = css_bus_match,
1534         .probe    = css_probe,
1535         .remove   = css_remove,
1536         .shutdown = css_shutdown,
1537         .uevent   = css_uevent,
1538         .pm = &css_pm_ops,
1539 };
1540
1541 /**
1542  * css_driver_register - register a css driver
1543  * @cdrv: css driver to register
1544  *
1545  * This is mainly a wrapper around driver_register that sets name
1546  * and bus_type in the embedded struct device_driver correctly.
1547  */
1548 int css_driver_register(struct css_driver *cdrv)
1549 {
1550         cdrv->drv.bus = &css_bus_type;
1551         return driver_register(&cdrv->drv);
1552 }
1553 EXPORT_SYMBOL_GPL(css_driver_register);
1554
1555 /**
1556  * css_driver_unregister - unregister a css driver
1557  * @cdrv: css driver to unregister
1558  *
1559  * This is a wrapper around driver_unregister.
1560  */
1561 void css_driver_unregister(struct css_driver *cdrv)
1562 {
1563         driver_unregister(&cdrv->drv);
1564 }
1565 EXPORT_SYMBOL_GPL(css_driver_unregister);