drivers/s390/cio/css.c

   1 /*
   2  *  drivers/s390/cio/css.c
   3  *  driver for channel subsystem
   4  *   $Revision: 1.77 $
   5  *
   6  *    Copyright (C) 2002 IBM Deutschland Entwicklung GmbH,
   7  *                       IBM Corporation
   8  *    Author(s): Arnd Bergmann (arndb@de.ibm.com)
   9  *               Cornelia Huck (cohuck@de.ibm.com)
  10  */
  11 #include <linux/module.h>
  12 #include <linux/init.h>
  13 #include <linux/device.h>
  14 #include <linux/slab.h>
  15 #include <linux/errno.h>
  16 #include <linux/list.h>
  17
  18 #include "css.h"
  19 #include "cio.h"
  20 #include "cio_debug.h"
  21 #include "ioasm.h"
  22
  23 unsigned int highest_subchannel;
  24 int need_rescan = 0;
  25 int css_init_done = 0;
  26
  27 struct device css_bus_device = {
  28         .bus_id = "css0",
  29 };
  30
  31 static struct subchannel *
  32 css_alloc_subchannel(int irq)
  33 {
  34         struct subchannel *sch;
  35         int ret;
  36
  37         sch = kmalloc (sizeof (*sch), GFP_KERNEL | GFP_DMA);
  38         if (sch == NULL)
  39                 return ERR_PTR(-ENOMEM);
  40         ret = cio_validate_subchannel (sch, irq);
  41         if (ret < 0) {
  42                 kfree(sch);
  43                 return ERR_PTR(ret);
  44         }
  45         if (irq > highest_subchannel)
  46                 highest_subchannel = irq;
  47
  48         if (sch->st != SUBCHANNEL_TYPE_IO) {
  49                 /* For now we ignore all non-io subchannels. */
  50                 kfree(sch);
  51                 return ERR_PTR(-EINVAL);
  52         }
  53
  54         /*
  55          * Set intparm to subchannel address.
  56          * This is fine even on 64bit since the subchannel is always located
  57          * under 2G.
  58          */
  59         sch->schib.pmcw.intparm = (__u32)(unsigned long)sch;
  60         ret = cio_modify(sch);
  61         if (ret) {
  62                 kfree(sch);
  63                 return ERR_PTR(ret);
  64         }
  65         return sch;
  66 }
  67
  68 static void
  69 css_free_subchannel(struct subchannel *sch)
  70 {
  71         if (sch) {
  72                 /* Reset intparm to zeroes. */
  73                 sch->schib.pmcw.intparm = 0;
  74                 cio_modify(sch);
  75                 kfree(sch);
  76         }
  77
  78 }
  79
  80 static void
  81 css_subchannel_release(struct device *dev)
  82 {
  83         struct subchannel *sch;
  84
  85         sch = to_subchannel(dev);
  86         if (!cio_is_console(sch->irq))
  87                 kfree(sch);
  88 }
  89
  90 extern int css_get_ssd_info(struct subchannel *sch);
  91
  92 static int
  93 css_register_subchannel(struct subchannel *sch)
  94 {
  95         int ret;
  96
  97         /* Initialize the subchannel structure */
  98         sch->dev.parent = &css_bus_device;
  99         sch->dev.bus = &css_bus_type;
 100         sch->dev.release = &css_subchannel_release;
 101
 102         /* make it known to the system */
 103         ret = device_register(&sch->dev);
 104         if (ret)
 105                 printk (KERN_WARNING "%s: could not register %s\n",
 106                         __func__, sch->dev.bus_id);
 107         else
 108                 css_get_ssd_info(sch);
 109         return ret;
 110 }
 111
 112 int
 113 css_probe_device(int irq)
 114 {
 115         int ret;
 116         struct subchannel *sch;
 117
 118         sch = css_alloc_subchannel(irq);
 119         if (IS_ERR(sch))
 120                 return PTR_ERR(sch);
 121         ret = css_register_subchannel(sch);
 122         if (ret)
 123                 css_free_subchannel(sch);
 124         return ret;
 125 }
 126
 127 struct subchannel *
 128 get_subchannel_by_schid(int irq)
 129 {
 130         struct subchannel *sch;
 131         struct list_head *entry;
 132         struct device *dev;
 133
 134         if (!get_bus(&css_bus_type))
 135                 return NULL;
 136         down_read(&css_bus_type.subsys.rwsem);
 137         sch = NULL;
 138         list_for_each(entry, &css_bus_type.devices.list) {
 139                 dev = get_device(container_of(entry,
 140                                               struct device, bus_list));
 141                 if (!dev)
 142                         continue;
 143                 sch = to_subchannel(dev);
 144                 if (sch->irq == irq)
 145                         break;
 146                 put_device(dev);
 147                 sch = NULL;
 148         }
 149         up_read(&css_bus_type.subsys.rwsem);
 150         put_bus(&css_bus_type);
 151
 152         return sch;
 153 }
 154
 155 static inline int
 156 css_get_subchannel_status(struct subchannel *sch, int schid)
 157 {
 158         struct schib schib;
 159         int cc;
 160
 161         cc = stsch(schid, &schib);
 162         if (cc)
 163                 return CIO_GONE;
 164         if (!schib.pmcw.dnv)
 165                 return CIO_GONE;
 166         if (sch && sch->schib.pmcw.dnv &&
 167             (schib.pmcw.dev != sch->schib.pmcw.dev))
 168                 return CIO_REVALIDATE;
 169         if (sch && !sch->lpm)
 170                 return CIO_NO_PATH;
 171         return CIO_OPER;
 172 }
 173
 174 static int
 175 css_evaluate_subchannel(int irq, int slow)
 176 {
 177         int event, ret, disc;
 178         struct subchannel *sch;
 179
 180         sch = get_subchannel_by_schid(irq);
 181         disc = sch ? device_is_disconnected(sch) : 0;
 182         if (disc && slow) {
 183                 if (sch)
 184                         put_device(&sch->dev);
 185                 return 0; /* Already processed. */
 186         }
 187         if (!disc && !slow) {
 188                 if (sch)
 189                         put_device(&sch->dev);
 190                 return -EAGAIN; /* Will be done on the slow path. */
 191         }
 192         event = css_get_subchannel_status(sch, irq);
 193         CIO_MSG_EVENT(4, "Evaluating schid %04x, event %d, %s, %s path.\n",
 194                       irq, event, sch?(disc?"disconnected":"normal"):"unknown",
 195                       slow?"slow":"fast");
 196         switch (event) {
 197         case CIO_NO_PATH:
 198         case CIO_GONE:
 199                 if (!sch) {
 200                         /* Never used this subchannel. Ignore. */
 201                         ret = 0;
 202                         break;
 203                 }
 204                 if (sch->driver && sch->driver->notify &&
 205                     sch->driver->notify(&sch->dev, event)) {
 206                         cio_disable_subchannel(sch);
 207                         device_set_disconnected(sch);
 208                         ret = 0;
 209                         break;
 210                 }
 211                 /*
 212                  * Unregister subchannel.
 213                  * The device will be killed automatically.
 214                  */
 215                 cio_disable_subchannel(sch);
 216                 device_unregister(&sch->dev);
 217                 /* Reset intparm to zeroes. */
 218                 sch->schib.pmcw.intparm = 0;
 219                 cio_modify(sch);
 220                 put_device(&sch->dev);
 221                 ret = 0;
 222                 break;
 223         case CIO_REVALIDATE:
 224                 /*
 225                  * Revalidation machine check. Sick.
 226                  * We don't notify the driver since we have to throw the device
 227                  * away in any case.
 228                  */
 229                 if (!disc) {
 230                         device_unregister(&sch->dev);
 231                         /* Reset intparm to zeroes. */
 232                         sch->schib.pmcw.intparm = 0;
 233                         cio_modify(sch);
 234                         put_device(&sch->dev);
 235                         ret = css_probe_device(irq);
 236                 } else {
 237                         /*
 238                          * We can't immediately deregister the disconnected
 239                          * device since it might block.
 240                          */
 241                         device_trigger_reprobe(sch);
 242                         ret = 0;
 243                 }
 244                 break;
 245         case CIO_OPER:
 246                 if (disc)
 247                         /* Get device operational again. */
 248                         device_trigger_reprobe(sch);
 249                 ret = sch ? 0 : css_probe_device(irq);
 250                 break;
 251         default:
 252                 BUG();
 253                 ret = 0;
 254         }
 255         return ret;
 256 }
 257
 258 static void
 259 css_rescan_devices(void)
 260 {
 261         int irq, ret;
 262
 263         for (irq = 0; irq <= __MAX_SUBCHANNELS; irq++) {
 264                 ret = css_evaluate_subchannel(irq, 1);
 265                 /* No more memory. It doesn't make sense to continue. No
 266                  * panic because this can happen in midflight and just
 267                  * because we can't use a new device is no reason to crash
 268                  * the system. */
 269                 if (ret == -ENOMEM)
 270                         break;
 271                 /* -ENXIO indicates that there are no more subchannels. */
 272                 if (ret == -ENXIO)
 273                         break;
 274         }
 275 }
 276
 277 struct slow_subchannel {
 278         struct list_head slow_list;
 279         unsigned long schid;
 280 };
 281
 282 static LIST_HEAD(slow_subchannels_head);
 283 static spinlock_t slow_subchannel_lock = SPIN_LOCK_UNLOCKED;
 284
 285 static void
 286 css_trigger_slow_path(void)
 287 {
 288         CIO_TRACE_EVENT(4, "slowpath");
 289
 290         if (need_rescan) {
 291                 need_rescan = 0;
 292                 css_rescan_devices();
 293                 return;
 294         }
 295
 296         spin_lock_irq(&slow_subchannel_lock);
 297         while (!list_empty(&slow_subchannels_head)) {
 298                 struct slow_subchannel *slow_sch =
 299                         list_entry(slow_subchannels_head.next,
 300                                    struct slow_subchannel, slow_list);
 301
 302                 list_del_init(slow_subchannels_head.next);
 303                 spin_unlock_irq(&slow_subchannel_lock);
 304                 css_evaluate_subchannel(slow_sch->schid, 1);
 305                 spin_lock_irq(&slow_subchannel_lock);
 306                 kfree(slow_sch);
 307         }
 308         spin_unlock_irq(&slow_subchannel_lock);
 309 }
 310
 311 typedef void (*workfunc)(void *);
 312 DECLARE_WORK(slow_path_work, (workfunc)css_trigger_slow_path, NULL);
 313 struct workqueue_struct *slow_path_wq;
 314
 315 /*
 316  * Rescan for new devices. FIXME: This is slow.
 317  * This function is called when we have lost CRWs due to overflows and we have
 318  * to do subchannel housekeeping.
 319  */
 320 void
 321 css_reiterate_subchannels(void)
 322 {
 323         css_clear_subchannel_slow_list();
 324         need_rescan = 1;
 325 }
 326
 327 /*
 328  * Called from the machine check handler for subchannel report words.
 329  */
 330 int
 331 css_process_crw(int irq)
 332 {
 333         int ret;
 334
 335         CIO_CRW_EVENT(2, "source is subchannel %04X\n", irq);
 336
 337         if (need_rescan)
 338                 /* We need to iterate all subchannels anyway. */
 339                 return -EAGAIN;
 340         /*
 341          * Since we are always presented with IPI in the CRW, we have to
 342          * use stsch() to find out if the subchannel in question has come
 343          * or gone.
 344          */
 345         ret = css_evaluate_subchannel(irq, 0);
 346         if (ret == -EAGAIN) {
 347                 if (css_enqueue_subchannel_slow(irq)) {
 348                         css_clear_subchannel_slow_list();
 349                         need_rescan = 1;
 350                 }
 351         }
 352         return ret;
 353 }
 354
 355 /*
 356  * some of the initialization has already been done from init_IRQ(),
 357  * here we do the rest now that the driver core is running.
 358  * The struct subchannel's are created during probing (except for the
 359  * static console subchannel).
 360  */
 361 static int __init
 362 init_channel_subsystem (void)
 363 {
 364         int ret, irq;
 365
 366         if ((ret = bus_register(&css_bus_type)))
 367                 goto out;
 368         if ((ret = device_register (&css_bus_device)))
 369                 goto out_bus;
 370
 371         css_init_done = 1;
 372
 373         ctl_set_bit(6, 28);
 374
 375         for (irq = 0; irq < __MAX_SUBCHANNELS; irq++) {
 376                 struct subchannel *sch;
 377
 378                 if (cio_is_console(irq))
 379                         sch = cio_get_console_subchannel();
 380                 else {
 381                         sch = css_alloc_subchannel(irq);
 382                         if (IS_ERR(sch))
 383                                 ret = PTR_ERR(sch);
 384                         else
 385                                 ret = 0;
 386                         if (ret == -ENOMEM)
 387                                 panic("Out of memory in "
 388                                       "init_channel_subsystem\n");
 389                         /* -ENXIO: no more subchannels. */
 390                         if (ret == -ENXIO)
 391                                 break;
 392                         if (ret)
 393                                 continue;
 394                 }
 395                 /*
 396                  * We register ALL valid subchannels in ioinfo, even those
 397                  * that have been present before init_channel_subsystem.
 398                  * These subchannels can't have been registered yet (kmalloc
 399                  * not working) so we do it now. This is true e.g. for the
 400                  * console subchannel.
 401                  */
 402                 css_register_subchannel(sch);
 403         }
 404         return 0;
 405
 406 out_bus:
 407         bus_unregister(&css_bus_type);
 408 out:
 409         return ret;
 410 }
 411
 412 /*
 413  * find a driver for a subchannel. They identify by the subchannel
 414  * type with the exception that the console subchannel driver has its own
 415  * subchannel type although the device is an i/o subchannel
 416  */
 417 static int
 418 css_bus_match (struct device *dev, struct device_driver *drv)
 419 {
 420         struct subchannel *sch = container_of (dev, struct subchannel, dev);
 421         struct css_driver *driver = container_of (drv, struct css_driver, drv);
 422
 423         if (sch->st == driver->subchannel_type)
 424                 return 1;
 425
 426         return 0;
 427 }
 428
 429 struct bus_type css_bus_type = {
 430         .name  = "css",
 431         .match = &css_bus_match,
 432 };
 433
 434 subsys_initcall(init_channel_subsystem);
 435
 436 /*
 437  * Register root devices for some drivers. The release function must not be
 438  * in the device drivers, so we do it here.
 439  */
 440 static void
 441 s390_root_dev_release(struct device *dev)
 442 {
 443         kfree(dev);
 444 }
 445
 446 struct device *
 447 s390_root_dev_register(const char *name)
 448 {
 449         struct device *dev;
 450         int ret;
 451
 452         if (!strlen(name))
 453                 return ERR_PTR(-EINVAL);
 454         dev = kmalloc(sizeof(struct device), GFP_KERNEL);
 455         if (!dev)
 456                 return ERR_PTR(-ENOMEM);
 457         memset(dev, 0, sizeof(struct device));
 458         strncpy(dev->bus_id, name, min(strlen(name), (size_t)BUS_ID_SIZE));
 459         dev->release = s390_root_dev_release;
 460         ret = device_register(dev);
 461         if (ret) {
 462                 kfree(dev);
 463                 return ERR_PTR(ret);
 464         }
 465         return dev;
 466 }
 467
 468 void
 469 s390_root_dev_unregister(struct device *dev)
 470 {
 471         if (dev)
 472                 device_unregister(dev);
 473 }
 474
 475 int
 476 css_enqueue_subchannel_slow(unsigned long schid)
 477 {
 478         struct slow_subchannel *new_slow_sch;
 479         unsigned long flags;
 480
 481         new_slow_sch = kmalloc(sizeof(struct slow_subchannel), GFP_ATOMIC);
 482         if (!new_slow_sch)
 483                 return -ENOMEM;
 484         new_slow_sch->schid = schid;
 485         spin_lock_irqsave(&slow_subchannel_lock, flags);
 486         list_add_tail(&new_slow_sch->slow_list, &slow_subchannels_head);
 487         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 488         return 0;
 489 }
 490
 491 void
 492 css_clear_subchannel_slow_list(void)
 493 {
 494         unsigned long flags;
 495
 496         spin_lock_irqsave(&slow_subchannel_lock, flags);
 497         while (!list_empty(&slow_subchannels_head)) {
 498                 struct slow_subchannel *slow_sch =
 499                         list_entry(slow_subchannels_head.next,
 500                                    struct slow_subchannel, slow_list);
 501
 502                 list_del_init(slow_subchannels_head.next);
 503                 kfree(slow_sch);
 504         }
 505         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 506 }
 507
 508
 509
 510 int
 511 css_slow_subchannels_exist(void)
 512 {
 513         return (!list_empty(&slow_subchannels_head));
 514 }
 515
 516 MODULE_LICENSE("GPL");
 517 EXPORT_SYMBOL(css_bus_type);
 518 EXPORT_SYMBOL(s390_root_dev_register);
 519 EXPORT_SYMBOL(s390_root_dev_unregister);