kernel/time/clockevents.c

   1 /*
   2  * linux/kernel/time/clockevents.c
   3  *
   4  * This file contains functions which manage clock event devices.
   5  *
   6  * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
   7  * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
   8  * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
   9  *
  10  * This code is licenced under the GPL version 2. For details see
  11  * kernel-base/COPYING.
  12  */
  13
  14 #include <linux/clockchips.h>
  15 #include <linux/hrtimer.h>
  16 #include <linux/init.h>
  17 #include <linux/module.h>
  18 #include <linux/smp.h>
  19 #include <linux/device.h>
  20
  21 #include "tick-internal.h"
  22
  23 /* The registered clock event devices */
  24 static LIST_HEAD(clockevent_devices);
  25 static LIST_HEAD(clockevents_released);
  26 /* Protection for the above */
  27 static DEFINE_RAW_SPINLOCK(clockevents_lock);
  28 /* Protection for unbind operations */
  29 static DEFINE_MUTEX(clockevents_mutex);
  30
  31 struct ce_unbind {
  32         struct clock_event_device *ce;
  33         int res;
  34 };
  35
  36 static u64 cev_delta2ns(unsigned long latch, struct clock_event_device *evt,
  37                         bool ismax)
  38 {
  39         u64 clc = (u64) latch << evt->shift;
  40         u64 rnd;
  41
  42         if (unlikely(!evt->mult)) {
  43                 evt->mult = 1;
  44                 WARN_ON(1);
  45         }
  46         rnd = (u64) evt->mult - 1;
  47
  48         /*
  49          * Upper bound sanity check. If the backwards conversion is
  50          * not equal latch, we know that the above shift overflowed.
  51          */
  52         if ((clc >> evt->shift) != (u64)latch)
  53                 clc = ~0ULL;
  54
  55         /*
  56          * Scaled math oddities:
  57          *
  58          * For mult <= (1 << shift) we can safely add mult - 1 to
  59          * prevent integer rounding loss. So the backwards conversion
  60          * from nsec to device ticks will be correct.
  61          *
  62          * For mult > (1 << shift), i.e. device frequency is > 1GHz we
  63          * need to be careful. Adding mult - 1 will result in a value
  64          * which when converted back to device ticks can be larger
  65          * than latch by up to (mult - 1) >> shift. For the min_delta
  66          * calculation we still want to apply this in order to stay
  67          * above the minimum device ticks limit. For the upper limit
  68          * we would end up with a latch value larger than the upper
  69          * limit of the device, so we omit the add to stay below the
  70          * device upper boundary.
  71          *
  72          * Also omit the add if it would overflow the u64 boundary.
  73          */
  74         if ((~0ULL - clc > rnd) &&
  75             (!ismax || evt->mult <= (1U << evt->shift)))
  76                 clc += rnd;
  77
  78         do_div(clc, evt->mult);
  79
  80         /* Deltas less than 1usec are pointless noise */
  81         return clc > 1000 ? clc : 1000;
  82 }
  83
  84 /**
  85  * clockevents_delta2ns - Convert a latch value (device ticks) to nanoseconds
  86  * @latch:      value to convert
  87  * @evt:        pointer to clock event device descriptor
  88  *
  89  * Math helper, returns latch value converted to nanoseconds (bound checked)
  90  */
  91 u64 clockevent_delta2ns(unsigned long latch, struct clock_event_device *evt)
  92 {
  93         return cev_delta2ns(latch, evt, false);
  94 }
  95 EXPORT_SYMBOL_GPL(clockevent_delta2ns);
  96
  97 /**
  98  * clockevents_set_mode - set the operating mode of a clock event device
  99  * @dev:        device to modify
 100  * @mode:       new mode
 101  *
 102  * Must be called with interrupts disabled !
 103  */
 104 void clockevents_set_mode(struct clock_event_device *dev,
 105                                  enum clock_event_mode mode)
 106 {
 107         if (dev->mode != mode) {
 108                 dev->set_mode(mode, dev);
 109                 dev->mode = mode;
 110
 111                 /*
 112                  * A nsec2cyc multiplicator of 0 is invalid and we'd crash
 113                  * on it, so fix it up and emit a warning:
 114                  */
 115                 if (mode == CLOCK_EVT_MODE_ONESHOT) {
 116                         if (unlikely(!dev->mult)) {
 117                                 dev->mult = 1;
 118                                 WARN_ON(1);
 119                         }
 120                 }
 121         }
 122 }
 123
 124 /**
 125  * clockevents_shutdown - shutdown the device and clear next_event
 126  * @dev:        device to shutdown
 127  */
 128 void clockevents_shutdown(struct clock_event_device *dev)
 129 {
 130         clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
 131         dev->next_event.tv64 = KTIME_MAX;
 132 }
 133
 134 #ifdef CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST
 135
 136 /* Limit min_delta to a jiffie */
 137 #define MIN_DELTA_LIMIT         (NSEC_PER_SEC / HZ)
 138
 139 /**
 140  * clockevents_increase_min_delta - raise minimum delta of a clock event device
 141  * @dev:       device to increase the minimum delta
 142  *
 143  * Returns 0 on success, -ETIME when the minimum delta reached the limit.
 144  */
 145 static int clockevents_increase_min_delta(struct clock_event_device *dev)
 146 {
 147         /* Nothing to do if we already reached the limit */
 148         if (dev->min_delta_ns >= MIN_DELTA_LIMIT) {
 149                 printk(KERN_WARNING "CE: Reprogramming failure. Giving up\n");
 150                 dev->next_event.tv64 = KTIME_MAX;
 151                 return -ETIME;
 152         }
 153
 154         if (dev->min_delta_ns < 5000)
 155                 dev->min_delta_ns = 5000;
 156         else
 157                 dev->min_delta_ns += dev->min_delta_ns >> 1;
 158
 159         if (dev->min_delta_ns > MIN_DELTA_LIMIT)
 160                 dev->min_delta_ns = MIN_DELTA_LIMIT;
 161
 162         printk(KERN_WARNING "CE: %s increased min_delta_ns to %llu nsec\n",
 163                dev->name ? dev->name : "?",
 164                (unsigned long long) dev->min_delta_ns);
 165         return 0;
 166 }
 167
 168 /**
 169  * clockevents_program_min_delta - Set clock event device to the minimum delay.
 170  * @dev:        device to program
 171  *
 172  * Returns 0 on success, -ETIME when the retry loop failed.
 173  */
 174 static int clockevents_program_min_delta(struct clock_event_device *dev)
 175 {
 176         unsigned long long clc;
 177         int64_t delta;
 178         int i;
 179
 180         for (i = 0;;) {
 181                 delta = dev->min_delta_ns;
 182                 dev->next_event = ktime_add_ns(ktime_get(), delta);
 183
 184                 if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN)
 185                         return 0;
 186
 187                 dev->retries++;
 188                 clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
 189                 if (dev->set_next_event((unsigned long) clc, dev) == 0)
 190                         return 0;
 191
 192                 if (++i > 2) {
 193                         /*
 194                          * We tried 3 times to program the device with the
 195                          * given min_delta_ns. Try to increase the minimum
 196                          * delta, if that fails as well get out of here.
 197                          */
 198                         if (clockevents_increase_min_delta(dev))
 199                                 return -ETIME;
 200                         i = 0;
 201                 }
 202         }
 203 }
 204
 205 #else  /* CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST */
 206
 207 /**
 208  * clockevents_program_min_delta - Set clock event device to the minimum delay.
 209  * @dev:        device to program
 210  *
 211  * Returns 0 on success, -ETIME when the retry loop failed.
 212  */
 213 static int clockevents_program_min_delta(struct clock_event_device *dev)
 214 {
 215         unsigned long long clc;
 216         int64_t delta;
 217
 218         delta = dev->min_delta_ns;
 219         dev->next_event = ktime_add_ns(ktime_get(), delta);
 220
 221         if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN)
 222                 return 0;
 223
 224         dev->retries++;
 225         clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
 226         return dev->set_next_event((unsigned long) clc, dev);
 227 }
 228
 229 #endif /* CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST */
 230
 231 /**
 232  * clockevents_program_event - Reprogram the clock event device.
 233  * @dev:        device to program
 234  * @expires:    absolute expiry time (monotonic clock)
 235  * @force:      program minimum delay if expires can not be set
 236  *
 237  * Returns 0 on success, -ETIME when the event is in the past.
 238  */
 239 int clockevents_program_event(struct clock_event_device *dev, ktime_t expires,
 240                               bool force)
 241 {
 242         unsigned long long clc;
 243         int64_t delta;
 244         int rc;
 245
 246         if (unlikely(expires.tv64 < 0)) {
 247                 WARN_ON_ONCE(1);
 248                 return -ETIME;
 249         }
 250
 251         dev->next_event = expires;
 252
 253         if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN)
 254                 return 0;
 255
 256         /* Shortcut for clockevent devices that can deal with ktime. */
 257         if (dev->features & CLOCK_EVT_FEAT_KTIME)
 258                 return dev->set_next_ktime(expires, dev);
 259
 260         delta = ktime_to_ns(ktime_sub(expires, ktime_get()));
 261         if (delta <= 0)
 262                 return force ? clockevents_program_min_delta(dev) : -ETIME;
 263
 264         delta = min(delta, (int64_t) dev->max_delta_ns);
 265         delta = max(delta, (int64_t) dev->min_delta_ns);
 266
 267         clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
 268         rc = dev->set_next_event((unsigned long) clc, dev);
 269
 270         return (rc && force) ? clockevents_program_min_delta(dev) : rc;
 271 }
 272
 273 /*
 274  * Called after a notify add to make devices available which were
 275  * released from the notifier call.
 276  */
 277 static void clockevents_notify_released(void)
 278 {
 279         struct clock_event_device *dev;
 280
 281         while (!list_empty(&clockevents_released)) {
 282                 dev = list_entry(clockevents_released.next,
 283                                  struct clock_event_device, list);
 284                 list_del(&dev->list);
 285                 list_add(&dev->list, &clockevent_devices);
 286                 tick_check_new_device(dev);
 287         }
 288 }
 289
 290 /*
 291  * Try to install a replacement clock event device
 292  */
 293 static int clockevents_replace(struct clock_event_device *ced)
 294 {
 295         struct clock_event_device *dev, *newdev = NULL;
 296
 297         list_for_each_entry(dev, &clockevent_devices, list) {
 298                 if (dev == ced || dev->mode != CLOCK_EVT_MODE_UNUSED)
 299                         continue;
 300
 301                 if (!tick_check_replacement(newdev, dev))
 302                         continue;
 303
 304                 if (!try_module_get(dev->owner))
 305                         continue;
 306
 307                 if (newdev)
 308                         module_put(newdev->owner);
 309                 newdev = dev;
 310         }
 311         if (newdev) {
 312                 tick_install_replacement(newdev);
 313                 list_del_init(&ced->list);
 314         }
 315         return newdev ? 0 : -EBUSY;
 316 }
 317
 318 /*
 319  * Called with clockevents_mutex and clockevents_lock held
 320  */
 321 static int __clockevents_try_unbind(struct clock_event_device *ced, int cpu)
 322 {
 323         /* Fast track. Device is unused */
 324         if (ced->mode == CLOCK_EVT_MODE_UNUSED) {
 325                 list_del_init(&ced->list);
 326                 return 0;
 327         }
 328
 329         return ced == per_cpu(tick_cpu_device, cpu).evtdev ? -EAGAIN : -EBUSY;
 330 }
 331
 332 /*
 333  * SMP function call to unbind a device
 334  */
 335 static void __clockevents_unbind(void *arg)
 336 {
 337         struct ce_unbind *cu = arg;
 338         int res;
 339
 340         raw_spin_lock(&clockevents_lock);
 341         res = __clockevents_try_unbind(cu->ce, smp_processor_id());
 342         if (res == -EAGAIN)
 343                 res = clockevents_replace(cu->ce);
 344         cu->res = res;
 345         raw_spin_unlock(&clockevents_lock);
 346 }
 347
 348 /*
 349  * Issues smp function call to unbind a per cpu device. Called with
 350  * clockevents_mutex held.
 351  */
 352 static int clockevents_unbind(struct clock_event_device *ced, int cpu)
 353 {
 354         struct ce_unbind cu = { .ce = ced, .res = -ENODEV };
 355
 356         smp_call_function_single(cpu, __clockevents_unbind, &cu, 1);
 357         return cu.res;
 358 }
 359
 360 /*
 361  * Unbind a clockevents device.
 362  */
 363 int clockevents_unbind_device(struct clock_event_device *ced, int cpu)
 364 {
 365         int ret;
 366
 367         mutex_lock(&clockevents_mutex);
 368         ret = clockevents_unbind(ced, cpu);
 369         mutex_unlock(&clockevents_mutex);
 370         return ret;
 371 }
 372 EXPORT_SYMBOL_GPL(clockevents_unbind);
 373
 374 /**
 375  * clockevents_register_device - register a clock event device
 376  * @dev:        device to register
 377  */
 378 void clockevents_register_device(struct clock_event_device *dev)
 379 {
 380         unsigned long flags;
 381
 382         BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED);
 383         if (!dev->cpumask) {
 384                 WARN_ON(num_possible_cpus() > 1);
 385                 dev->cpumask = cpumask_of(smp_processor_id());
 386         }
 387
 388         raw_spin_lock_irqsave(&clockevents_lock, flags);
 389
 390         list_add(&dev->list, &clockevent_devices);
 391         tick_check_new_device(dev);
 392         clockevents_notify_released();
 393
 394         raw_spin_unlock_irqrestore(&clockevents_lock, flags);
 395 }
 396 EXPORT_SYMBOL_GPL(clockevents_register_device);
 397
 398 void clockevents_config(struct clock_event_device *dev, u32 freq)
 399 {
 400         u64 sec;
 401
 402         if (!(dev->features & CLOCK_EVT_FEAT_ONESHOT))
 403                 return;
 404
 405         /*
 406          * Calculate the maximum number of seconds we can sleep. Limit
 407          * to 10 minutes for hardware which can program more than
 408          * 32bit ticks so we still get reasonable conversion values.
 409          */
 410         sec = dev->max_delta_ticks;
 411         do_div(sec, freq);
 412         if (!sec)
 413                 sec = 1;
 414         else if (sec > 600 && dev->max_delta_ticks > UINT_MAX)
 415                 sec = 600;
 416
 417         clockevents_calc_mult_shift(dev, freq, sec);
 418         dev->min_delta_ns = cev_delta2ns(dev->min_delta_ticks, dev, false);
 419         dev->max_delta_ns = cev_delta2ns(dev->max_delta_ticks, dev, true);
 420 }
 421
 422 /**
 423  * clockevents_config_and_register - Configure and register a clock event device
 424  * @dev:        device to register
 425  * @freq:       The clock frequency
 426  * @min_delta:  The minimum clock ticks to program in oneshot mode
 427  * @max_delta:  The maximum clock ticks to program in oneshot mode
 428  *
 429  * min/max_delta can be 0 for devices which do not support oneshot mode.
 430  */
 431 void clockevents_config_and_register(struct clock_event_device *dev,
 432                                      u32 freq, unsigned long min_delta,
 433                                      unsigned long max_delta)
 434 {
 435         dev->min_delta_ticks = min_delta;
 436         dev->max_delta_ticks = max_delta;
 437         clockevents_config(dev, freq);
 438         clockevents_register_device(dev);
 439 }
 440 EXPORT_SYMBOL_GPL(clockevents_config_and_register);
 441
 442 int __clockevents_update_freq(struct clock_event_device *dev, u32 freq)
 443 {
 444         clockevents_config(dev, freq);
 445
 446         if (dev->mode == CLOCK_EVT_MODE_ONESHOT)
 447                 return clockevents_program_event(dev, dev->next_event, false);
 448
 449         if (dev->mode == CLOCK_EVT_MODE_PERIODIC)
 450                 dev->set_mode(CLOCK_EVT_MODE_PERIODIC, dev);
 451
 452         return 0;
 453 }
 454
 455 /**
 456  * clockevents_update_freq - Update frequency and reprogram a clock event device.
 457  * @dev:        device to modify
 458  * @freq:       new device frequency
 459  *
 460  * Reconfigure and reprogram a clock event device in oneshot
 461  * mode. Must be called on the cpu for which the device delivers per
 462  * cpu timer events. If called for the broadcast device the core takes
 463  * care of serialization.
 464  *
 465  * Returns 0 on success, -ETIME when the event is in the past.
 466  */
 467 int clockevents_update_freq(struct clock_event_device *dev, u32 freq)
 468 {
 469         unsigned long flags;
 470         int ret;
 471
 472         local_irq_save(flags);
 473         ret = tick_broadcast_update_freq(dev, freq);
 474         if (ret == -ENODEV)
 475                 ret = __clockevents_update_freq(dev, freq);
 476         local_irq_restore(flags);
 477         return ret;
 478 }
 479
 480 /*
 481  * Noop handler when we shut down an event device
 482  */
 483 void clockevents_handle_noop(struct clock_event_device *dev)
 484 {
 485 }
 486
 487 /**
 488  * clockevents_exchange_device - release and request clock devices
 489  * @old:        device to release (can be NULL)
 490  * @new:        device to request (can be NULL)
 491  *
 492  * Called from the notifier chain. clockevents_lock is held already
 493  */
 494 void clockevents_exchange_device(struct clock_event_device *old,
 495                                  struct clock_event_device *new)
 496 {
 497         unsigned long flags;
 498
 499         local_irq_save(flags);
 500         /*
 501          * Caller releases a clock event device. We queue it into the
 502          * released list and do a notify add later.
 503          */
 504         if (old) {
 505                 module_put(old->owner);
 506                 clockevents_set_mode(old, CLOCK_EVT_MODE_UNUSED);
 507                 list_del(&old->list);
 508                 list_add(&old->list, &clockevents_released);
 509         }
 510
 511         if (new) {
 512                 BUG_ON(new->mode != CLOCK_EVT_MODE_UNUSED);
 513                 clockevents_shutdown(new);
 514         }
 515         local_irq_restore(flags);
 516 }
 517
 518 /**
 519  * clockevents_suspend - suspend clock devices
 520  */
 521 void clockevents_suspend(void)
 522 {
 523         struct clock_event_device *dev;
 524
 525         list_for_each_entry_reverse(dev, &clockevent_devices, list)
 526                 if (dev->suspend)
 527                         dev->suspend(dev);
 528 }
 529
 530 /**
 531  * clockevents_resume - resume clock devices
 532  */
 533 void clockevents_resume(void)
 534 {
 535         struct clock_event_device *dev;
 536
 537         list_for_each_entry(dev, &clockevent_devices, list)
 538                 if (dev->resume)
 539                         dev->resume(dev);
 540 }
 541
 542 #ifdef CONFIG_GENERIC_CLOCKEVENTS
 543 /**
 544  * clockevents_notify - notification about relevant events
 545  * Returns 0 on success, any other value on error
 546  */
 547 int clockevents_notify(unsigned long reason, void *arg)
 548 {
 549         struct clock_event_device *dev, *tmp;
 550         unsigned long flags;
 551         int cpu, ret = 0;
 552
 553         raw_spin_lock_irqsave(&clockevents_lock, flags);
 554
 555         switch (reason) {
 556         case CLOCK_EVT_NOTIFY_BROADCAST_ON:
 557         case CLOCK_EVT_NOTIFY_BROADCAST_OFF:
 558         case CLOCK_EVT_NOTIFY_BROADCAST_FORCE:
 559                 tick_broadcast_on_off(reason, arg);
 560                 break;
 561
 562         case CLOCK_EVT_NOTIFY_BROADCAST_ENTER:
 563         case CLOCK_EVT_NOTIFY_BROADCAST_EXIT:
 564                 ret = tick_broadcast_oneshot_control(reason);
 565                 break;
 566
 567         case CLOCK_EVT_NOTIFY_CPU_DYING:
 568                 tick_handover_do_timer(arg);
 569                 break;
 570
 571         case CLOCK_EVT_NOTIFY_SUSPEND:
 572                 tick_suspend();
 573                 tick_suspend_broadcast();
 574                 break;
 575
 576         case CLOCK_EVT_NOTIFY_RESUME:
 577                 tick_resume();
 578                 break;
 579
 580         case CLOCK_EVT_NOTIFY_CPU_DEAD:
 581                 tick_shutdown_broadcast_oneshot(arg);
 582                 tick_shutdown_broadcast(arg);
 583                 tick_shutdown(arg);
 584                 /*
 585                  * Unregister the clock event devices which were
 586                  * released from the users in the notify chain.
 587                  */
 588                 list_for_each_entry_safe(dev, tmp, &clockevents_released, list)
 589                         list_del(&dev->list);
 590                 /*
 591                  * Now check whether the CPU has left unused per cpu devices
 592                  */
 593                 cpu = *((int *)arg);
 594                 list_for_each_entry_safe(dev, tmp, &clockevent_devices, list) {
 595                         if (cpumask_test_cpu(cpu, dev->cpumask) &&
 596                             cpumask_weight(dev->cpumask) == 1 &&
 597                             !tick_is_broadcast_device(dev)) {
 598                                 BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED);
 599                                 list_del(&dev->list);
 600                         }
 601                 }
 602                 break;
 603         default:
 604                 break;
 605         }
 606         raw_spin_unlock_irqrestore(&clockevents_lock, flags);
 607         return ret;
 608 }
 609 EXPORT_SYMBOL_GPL(clockevents_notify);
 610
 611 #ifdef CONFIG_SYSFS
 612 struct bus_type clockevents_subsys = {
 613         .name           = "clockevents",
 614         .dev_name       = "clockevent",
 615 };
 616
 617 static DEFINE_PER_CPU(struct device, tick_percpu_dev);
 618 static struct tick_device *tick_get_tick_dev(struct device *dev);
 619
 620 static ssize_t sysfs_show_current_tick_dev(struct device *dev,
 621                                            struct device_attribute *attr,
 622                                            char *buf)
 623 {
 624         struct tick_device *td;
 625         ssize_t count = 0;
 626
 627         raw_spin_lock_irq(&clockevents_lock);
 628         td = tick_get_tick_dev(dev);
 629         if (td && td->evtdev)
 630                 count = snprintf(buf, PAGE_SIZE, "%s\n", td->evtdev->name);
 631         raw_spin_unlock_irq(&clockevents_lock);
 632         return count;
 633 }
 634 static DEVICE_ATTR(current_device, 0444, sysfs_show_current_tick_dev, NULL);
 635
 636 /* We don't support the abomination of removable broadcast devices */
 637 static ssize_t sysfs_unbind_tick_dev(struct device *dev,
 638                                      struct device_attribute *attr,
 639                                      const char *buf, size_t count)
 640 {
 641         char name[CS_NAME_LEN];
 642         ssize_t ret = sysfs_get_uname(buf, name, count);
 643         struct clock_event_device *ce;
 644
 645         if (ret < 0)
 646                 return ret;
 647
 648         ret = -ENODEV;
 649         mutex_lock(&clockevents_mutex);
 650         raw_spin_lock_irq(&clockevents_lock);
 651         list_for_each_entry(ce, &clockevent_devices, list) {
 652                 if (!strcmp(ce->name, name)) {
 653                         ret = __clockevents_try_unbind(ce, dev->id);
 654                         break;
 655                 }
 656         }
 657         raw_spin_unlock_irq(&clockevents_lock);
 658         /*
 659          * We hold clockevents_mutex, so ce can't go away
 660          */
 661         if (ret == -EAGAIN)
 662                 ret = clockevents_unbind(ce, dev->id);
 663         mutex_unlock(&clockevents_mutex);
 664         return ret ? ret : count;
 665 }
 666 static DEVICE_ATTR(unbind_device, 0200, NULL, sysfs_unbind_tick_dev);
 667
 668 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 669 static struct device tick_bc_dev = {
 670         .init_name      = "broadcast",
 671         .id             = 0,
 672         .bus            = &clockevents_subsys,
 673 };
 674
 675 static struct tick_device *tick_get_tick_dev(struct device *dev)
 676 {
 677         return dev == &tick_bc_dev ? tick_get_broadcast_device() :
 678                 &per_cpu(tick_cpu_device, dev->id);
 679 }
 680
 681 static __init int tick_broadcast_init_sysfs(void)
 682 {
 683         int err = device_register(&tick_bc_dev);
 684
 685         if (!err)
 686                 err = device_create_file(&tick_bc_dev, &dev_attr_current_device);
 687         return err;
 688 }
 689 #else
 690 static struct tick_device *tick_get_tick_dev(struct device *dev)
 691 {
 692         return &per_cpu(tick_cpu_device, dev->id);
 693 }
 694 static inline int tick_broadcast_init_sysfs(void) { return 0; }
 695 #endif
 696
 697 static int __init tick_init_sysfs(void)
 698 {
 699         int cpu;
 700
 701         for_each_possible_cpu(cpu) {
 702                 struct device *dev = &per_cpu(tick_percpu_dev, cpu);
 703                 int err;
 704
 705                 dev->id = cpu;
 706                 dev->bus = &clockevents_subsys;
 707                 err = device_register(dev);
 708                 if (!err)
 709                         err = device_create_file(dev, &dev_attr_current_device);
 710                 if (!err)
 711                         err = device_create_file(dev, &dev_attr_unbind_device);
 712                 if (err)
 713                         return err;
 714         }
 715         return tick_broadcast_init_sysfs();
 716 }
 717
 718 static int __init clockevents_init_sysfs(void)
 719 {
 720         int err = subsys_system_register(&clockevents_subsys, NULL);
 721
 722         if (!err)
 723                 err = tick_init_sysfs();
 724         return err;
 725 }
 726 device_initcall(clockevents_init_sysfs);
 727 #endif /* SYSFS */
 728
 729 #endif /* GENERIC_CLOCK_EVENTS */