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 */ 24static LIST_HEAD(clockevent_devices); 25static LIST_HEAD(clockevents_released); 26/* Protection for the above */ 27static DEFINE_RAW_SPINLOCK(clockevents_lock); 28/* Protection for unbind operations */ 29static DEFINE_MUTEX(clockevents_mutex); 30 31struct ce_unbind { 32 struct clock_event_device *ce; 33 int res; 34}; 35 36static 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 <= (1ULL << 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 */ 91u64 clockevent_delta2ns(unsigned long latch, struct clock_event_device *evt) 92{ 93 return cev_delta2ns(latch, evt, false); 94} 95EXPORT_SYMBOL_GPL(clockevent_delta2ns); 96 97static int __clockevents_set_state(struct clock_event_device *dev, 98 enum clock_event_state state) 99{ 100 /* Transition with legacy set_mode() callback */ 101 if (dev->set_mode) { 102 /* Legacy callback doesn't support new modes */ 103 if (state > CLOCK_EVT_STATE_ONESHOT) 104 return -ENOSYS; 105 /* 106 * 'clock_event_state' and 'clock_event_mode' have 1-to-1 107 * mapping until *_ONESHOT, and so a simple cast will work. 108 */ 109 dev->set_mode((enum clock_event_mode)state, dev); 110 dev->mode = (enum clock_event_mode)state; 111 return 0; 112 } 113 114 if (dev->features & CLOCK_EVT_FEAT_DUMMY) 115 return 0; 116 117 /* Transition with new state-specific callbacks */ 118 switch (state) { 119 case CLOCK_EVT_STATE_DETACHED: 120 /* The clockevent device is getting replaced. Shut it down. */ 121 122 case CLOCK_EVT_STATE_SHUTDOWN: 123 return dev->set_state_shutdown(dev); 124 125 case CLOCK_EVT_STATE_PERIODIC: 126 /* Core internal bug */ 127 if (!(dev->features & CLOCK_EVT_FEAT_PERIODIC)) 128 return -ENOSYS; 129 return dev->set_state_periodic(dev); 130 131 case CLOCK_EVT_STATE_ONESHOT: 132 /* Core internal bug */ 133 if (!(dev->features & CLOCK_EVT_FEAT_ONESHOT)) 134 return -ENOSYS; 135 return dev->set_state_oneshot(dev); 136 137 default: 138 return -ENOSYS; 139 } 140} 141 142/** 143 * clockevents_set_state - set the operating state of a clock event device 144 * @dev: device to modify 145 * @state: new state 146 * 147 * Must be called with interrupts disabled ! 148 */ 149void clockevents_set_state(struct clock_event_device *dev, 150 enum clock_event_state state) 151{ 152 if (dev->state != state) { 153 if (__clockevents_set_state(dev, state)) 154 return; 155 156 dev->state = state; 157 158 /* 159 * A nsec2cyc multiplicator of 0 is invalid and we'd crash 160 * on it, so fix it up and emit a warning: 161 */ 162 if (state == CLOCK_EVT_STATE_ONESHOT) { 163 if (unlikely(!dev->mult)) { 164 dev->mult = 1; 165 WARN_ON(1); 166 } 167 } 168 } 169} 170 171/** 172 * clockevents_shutdown - shutdown the device and clear next_event 173 * @dev: device to shutdown 174 */ 175void clockevents_shutdown(struct clock_event_device *dev) 176{ 177 clockevents_set_state(dev, CLOCK_EVT_STATE_SHUTDOWN); 178 dev->next_event.tv64 = KTIME_MAX; 179} 180 181/** 182 * clockevents_tick_resume - Resume the tick device before using it again 183 * @dev: device to resume 184 */ 185int clockevents_tick_resume(struct clock_event_device *dev) 186{ 187 int ret = 0; 188 189 if (dev->set_mode) { 190 dev->set_mode(CLOCK_EVT_MODE_RESUME, dev); 191 dev->mode = CLOCK_EVT_MODE_RESUME; 192 } else if (dev->tick_resume) { 193 ret = dev->tick_resume(dev); 194 } 195 196 return ret; 197} 198 199#ifdef CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST 200 201/* Limit min_delta to a jiffie */ 202#define MIN_DELTA_LIMIT (NSEC_PER_SEC / HZ) 203 204/** 205 * clockevents_increase_min_delta - raise minimum delta of a clock event device 206 * @dev: device to increase the minimum delta 207 * 208 * Returns 0 on success, -ETIME when the minimum delta reached the limit. 209 */ 210static int clockevents_increase_min_delta(struct clock_event_device *dev) 211{ 212 /* Nothing to do if we already reached the limit */ 213 if (dev->min_delta_ns >= MIN_DELTA_LIMIT) { 214 printk_deferred(KERN_WARNING 215 "CE: Reprogramming failure. Giving up\n"); 216 dev->next_event.tv64 = KTIME_MAX; 217 return -ETIME; 218 } 219 220 if (dev->min_delta_ns < 5000) 221 dev->min_delta_ns = 5000; 222 else 223 dev->min_delta_ns += dev->min_delta_ns >> 1; 224 225 if (dev->min_delta_ns > MIN_DELTA_LIMIT) 226 dev->min_delta_ns = MIN_DELTA_LIMIT; 227 228 printk_deferred(KERN_WARNING 229 "CE: %s increased min_delta_ns to %llu nsec\n", 230 dev->name ? dev->name : "?", 231 (unsigned long long) dev->min_delta_ns); 232 return 0; 233} 234 235/** 236 * clockevents_program_min_delta - Set clock event device to the minimum delay. 237 * @dev: device to program 238 * 239 * Returns 0 on success, -ETIME when the retry loop failed. 240 */ 241static int clockevents_program_min_delta(struct clock_event_device *dev) 242{ 243 unsigned long long clc; 244 int64_t delta; 245 int i; 246 247 for (i = 0;;) { 248 delta = dev->min_delta_ns; 249 dev->next_event = ktime_add_ns(ktime_get(), delta); 250 251 if (dev->state == CLOCK_EVT_STATE_SHUTDOWN) 252 return 0; 253 254 dev->retries++; 255 clc = ((unsigned long long) delta * dev->mult) >> dev->shift; 256 if (dev->set_next_event((unsigned long) clc, dev) == 0) 257 return 0; 258 259 if (++i > 2) { 260 /* 261 * We tried 3 times to program the device with the 262 * given min_delta_ns. Try to increase the minimum 263 * delta, if that fails as well get out of here. 264 */ 265 if (clockevents_increase_min_delta(dev)) 266 return -ETIME; 267 i = 0; 268 } 269 } 270} 271 272#else /* CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST */ 273 274/** 275 * clockevents_program_min_delta - Set clock event device to the minimum delay. 276 * @dev: device to program 277 * 278 * Returns 0 on success, -ETIME when the retry loop failed. 279 */ 280static int clockevents_program_min_delta(struct clock_event_device *dev) 281{ 282 unsigned long long clc; 283 int64_t delta; 284 285 delta = dev->min_delta_ns; 286 dev->next_event = ktime_add_ns(ktime_get(), delta); 287 288 if (dev->state == CLOCK_EVT_STATE_SHUTDOWN) 289 return 0; 290 291 dev->retries++; 292 clc = ((unsigned long long) delta * dev->mult) >> dev->shift; 293 return dev->set_next_event((unsigned long) clc, dev); 294} 295 296#endif /* CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST */ 297 298/** 299 * clockevents_program_event - Reprogram the clock event device. 300 * @dev: device to program 301 * @expires: absolute expiry time (monotonic clock) 302 * @force: program minimum delay if expires can not be set 303 * 304 * Returns 0 on success, -ETIME when the event is in the past. 305 */ 306int clockevents_program_event(struct clock_event_device *dev, ktime_t expires, 307 bool force) 308{ 309 unsigned long long clc; 310 int64_t delta; 311 int rc; 312 313 if (unlikely(expires.tv64 < 0)) { 314 WARN_ON_ONCE(1); 315 return -ETIME; 316 } 317 318 dev->next_event = expires; 319 320 if (dev->state == CLOCK_EVT_STATE_SHUTDOWN) 321 return 0; 322 323 /* Shortcut for clockevent devices that can deal with ktime. */ 324 if (dev->features & CLOCK_EVT_FEAT_KTIME) 325 return dev->set_next_ktime(expires, dev); 326 327 delta = ktime_to_ns(ktime_sub(expires, ktime_get())); 328 if (delta <= 0) 329 return force ? clockevents_program_min_delta(dev) : -ETIME; 330 331 delta = min(delta, (int64_t) dev->max_delta_ns); 332 delta = max(delta, (int64_t) dev->min_delta_ns); 333 334 clc = ((unsigned long long) delta * dev->mult) >> dev->shift; 335 rc = dev->set_next_event((unsigned long) clc, dev); 336 337 return (rc && force) ? clockevents_program_min_delta(dev) : rc; 338} 339 340/* 341 * Called after a notify add to make devices available which were 342 * released from the notifier call. 343 */ 344static void clockevents_notify_released(void) 345{ 346 struct clock_event_device *dev; 347 348 while (!list_empty(&clockevents_released)) { 349 dev = list_entry(clockevents_released.next, 350 struct clock_event_device, list); 351 list_del(&dev->list); 352 list_add(&dev->list, &clockevent_devices); 353 tick_check_new_device(dev); 354 } 355} 356 357/* 358 * Try to install a replacement clock event device 359 */ 360static int clockevents_replace(struct clock_event_device *ced) 361{ 362 struct clock_event_device *dev, *newdev = NULL; 363 364 list_for_each_entry(dev, &clockevent_devices, list) { 365 if (dev == ced || dev->state != CLOCK_EVT_STATE_DETACHED) 366 continue; 367 368 if (!tick_check_replacement(newdev, dev)) 369 continue; 370 371 if (!try_module_get(dev->owner)) 372 continue; 373 374 if (newdev) 375 module_put(newdev->owner); 376 newdev = dev; 377 } 378 if (newdev) { 379 tick_install_replacement(newdev); 380 list_del_init(&ced->list); 381 } 382 return newdev ? 0 : -EBUSY; 383} 384 385/* 386 * Called with clockevents_mutex and clockevents_lock held 387 */ 388static int __clockevents_try_unbind(struct clock_event_device *ced, int cpu) 389{ 390 /* Fast track. Device is unused */ 391 if (ced->state == CLOCK_EVT_STATE_DETACHED) { 392 list_del_init(&ced->list); 393 return 0; 394 } 395 396 return ced == per_cpu(tick_cpu_device, cpu).evtdev ? -EAGAIN : -EBUSY; 397} 398 399/* 400 * SMP function call to unbind a device 401 */ 402static void __clockevents_unbind(void *arg) 403{ 404 struct ce_unbind *cu = arg; 405 int res; 406 407 raw_spin_lock(&clockevents_lock); 408 res = __clockevents_try_unbind(cu->ce, smp_processor_id()); 409 if (res == -EAGAIN) 410 res = clockevents_replace(cu->ce); 411 cu->res = res; 412 raw_spin_unlock(&clockevents_lock); 413} 414 415/* 416 * Issues smp function call to unbind a per cpu device. Called with 417 * clockevents_mutex held. 418 */ 419static int clockevents_unbind(struct clock_event_device *ced, int cpu) 420{ 421 struct ce_unbind cu = { .ce = ced, .res = -ENODEV }; 422 423 smp_call_function_single(cpu, __clockevents_unbind, &cu, 1); 424 return cu.res; 425} 426 427/* 428 * Unbind a clockevents device. 429 */ 430int clockevents_unbind_device(struct clock_event_device *ced, int cpu) 431{ 432 int ret; 433 434 mutex_lock(&clockevents_mutex); 435 ret = clockevents_unbind(ced, cpu); 436 mutex_unlock(&clockevents_mutex); 437 return ret; 438} 439EXPORT_SYMBOL_GPL(clockevents_unbind_device); 440 441/* Sanity check of state transition callbacks */ 442static int clockevents_sanity_check(struct clock_event_device *dev) 443{ 444 /* Legacy set_mode() callback */ 445 if (dev->set_mode) { 446 /* We shouldn't be supporting new modes now */ 447 WARN_ON(dev->set_state_periodic || dev->set_state_oneshot || 448 dev->set_state_shutdown || dev->tick_resume); 449 450 BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED); 451 return 0; 452 } 453 454 if (dev->features & CLOCK_EVT_FEAT_DUMMY) 455 return 0; 456 457 /* New state-specific callbacks */ 458 if (!dev->set_state_shutdown) 459 return -EINVAL; 460 461 if ((dev->features & CLOCK_EVT_FEAT_PERIODIC) && 462 !dev->set_state_periodic) 463 return -EINVAL; 464 465 if ((dev->features & CLOCK_EVT_FEAT_ONESHOT) && 466 !dev->set_state_oneshot) 467 return -EINVAL; 468 469 return 0; 470} 471 472/** 473 * clockevents_register_device - register a clock event device 474 * @dev: device to register 475 */ 476void clockevents_register_device(struct clock_event_device *dev) 477{ 478 unsigned long flags; 479 480 BUG_ON(clockevents_sanity_check(dev)); 481 482 /* Initialize state to DETACHED */ 483 dev->state = CLOCK_EVT_STATE_DETACHED; 484 485 if (!dev->cpumask) { 486 WARN_ON(num_possible_cpus() > 1); 487 dev->cpumask = cpumask_of(smp_processor_id()); 488 } 489 490 raw_spin_lock_irqsave(&clockevents_lock, flags); 491 492 list_add(&dev->list, &clockevent_devices); 493 tick_check_new_device(dev); 494 clockevents_notify_released(); 495 496 raw_spin_unlock_irqrestore(&clockevents_lock, flags); 497} 498EXPORT_SYMBOL_GPL(clockevents_register_device); 499 500void clockevents_config(struct clock_event_device *dev, u32 freq) 501{ 502 u64 sec; 503 504 if (!(dev->features & CLOCK_EVT_FEAT_ONESHOT)) 505 return; 506 507 /* 508 * Calculate the maximum number of seconds we can sleep. Limit 509 * to 10 minutes for hardware which can program more than 510 * 32bit ticks so we still get reasonable conversion values. 511 */ 512 sec = dev->max_delta_ticks; 513 do_div(sec, freq); 514 if (!sec) 515 sec = 1; 516 else if (sec > 600 && dev->max_delta_ticks > UINT_MAX) 517 sec = 600; 518 519 clockevents_calc_mult_shift(dev, freq, sec); 520 dev->min_delta_ns = cev_delta2ns(dev->min_delta_ticks, dev, false); 521 dev->max_delta_ns = cev_delta2ns(dev->max_delta_ticks, dev, true); 522} 523 524/** 525 * clockevents_config_and_register - Configure and register a clock event device 526 * @dev: device to register 527 * @freq: The clock frequency 528 * @min_delta: The minimum clock ticks to program in oneshot mode 529 * @max_delta: The maximum clock ticks to program in oneshot mode 530 * 531 * min/max_delta can be 0 for devices which do not support oneshot mode. 532 */ 533void clockevents_config_and_register(struct clock_event_device *dev, 534 u32 freq, unsigned long min_delta, 535 unsigned long max_delta) 536{ 537 dev->min_delta_ticks = min_delta; 538 dev->max_delta_ticks = max_delta; 539 clockevents_config(dev, freq); 540 clockevents_register_device(dev); 541} 542EXPORT_SYMBOL_GPL(clockevents_config_and_register); 543 544int __clockevents_update_freq(struct clock_event_device *dev, u32 freq) 545{ 546 clockevents_config(dev, freq); 547 548 if (dev->state == CLOCK_EVT_STATE_ONESHOT) 549 return clockevents_program_event(dev, dev->next_event, false); 550 551 if (dev->state == CLOCK_EVT_STATE_PERIODIC) 552 return __clockevents_set_state(dev, CLOCK_EVT_STATE_PERIODIC); 553 554 return 0; 555} 556 557/** 558 * clockevents_update_freq - Update frequency and reprogram a clock event device. 559 * @dev: device to modify 560 * @freq: new device frequency 561 * 562 * Reconfigure and reprogram a clock event device in oneshot 563 * mode. Must be called on the cpu for which the device delivers per 564 * cpu timer events. If called for the broadcast device the core takes 565 * care of serialization. 566 * 567 * Returns 0 on success, -ETIME when the event is in the past. 568 */ 569int clockevents_update_freq(struct clock_event_device *dev, u32 freq) 570{ 571 unsigned long flags; 572 int ret; 573 574 local_irq_save(flags); 575 ret = tick_broadcast_update_freq(dev, freq); 576 if (ret == -ENODEV) 577 ret = __clockevents_update_freq(dev, freq); 578 local_irq_restore(flags); 579 return ret; 580} 581 582/* 583 * Noop handler when we shut down an event device 584 */ 585void clockevents_handle_noop(struct clock_event_device *dev) 586{ 587} 588 589/** 590 * clockevents_exchange_device - release and request clock devices 591 * @old: device to release (can be NULL) 592 * @new: device to request (can be NULL) 593 * 594 * Called from various tick functions with clockevents_lock held and 595 * interrupts disabled. 596 */ 597void clockevents_exchange_device(struct clock_event_device *old, 598 struct clock_event_device *new) 599{ 600 /* 601 * Caller releases a clock event device. We queue it into the 602 * released list and do a notify add later. 603 */ 604 if (old) { 605 module_put(old->owner); 606 clockevents_set_state(old, CLOCK_EVT_STATE_DETACHED); 607 list_del(&old->list); 608 list_add(&old->list, &clockevents_released); 609 } 610 611 if (new) { 612 BUG_ON(new->state != CLOCK_EVT_STATE_DETACHED); 613 clockevents_shutdown(new); 614 } 615} 616 617/** 618 * clockevents_suspend - suspend clock devices 619 */ 620void clockevents_suspend(void) 621{ 622 struct clock_event_device *dev; 623 624 list_for_each_entry_reverse(dev, &clockevent_devices, list) 625 if (dev->suspend) 626 dev->suspend(dev); 627} 628 629/** 630 * clockevents_resume - resume clock devices 631 */ 632void clockevents_resume(void) 633{ 634 struct clock_event_device *dev; 635 636 list_for_each_entry(dev, &clockevent_devices, list) 637 if (dev->resume) 638 dev->resume(dev); 639} 640 641#ifdef CONFIG_HOTPLUG_CPU 642/** 643 * tick_cleanup_dead_cpu - Cleanup the tick and clockevents of a dead cpu 644 */ 645void tick_cleanup_dead_cpu(int cpu) 646{ 647 struct clock_event_device *dev, *tmp; 648 unsigned long flags; 649 650 raw_spin_lock_irqsave(&clockevents_lock, flags); 651 652 tick_shutdown_broadcast_oneshot(cpu); 653 tick_shutdown_broadcast(cpu); 654 tick_shutdown(cpu); 655 /* 656 * Unregister the clock event devices which were 657 * released from the users in the notify chain. 658 */ 659 list_for_each_entry_safe(dev, tmp, &clockevents_released, list) 660 list_del(&dev->list); 661 /* 662 * Now check whether the CPU has left unused per cpu devices 663 */ 664 list_for_each_entry_safe(dev, tmp, &clockevent_devices, list) { 665 if (cpumask_test_cpu(cpu, dev->cpumask) && 666 cpumask_weight(dev->cpumask) == 1 && 667 !tick_is_broadcast_device(dev)) { 668 BUG_ON(dev->state != CLOCK_EVT_STATE_DETACHED); 669 list_del(&dev->list); 670 } 671 } 672 raw_spin_unlock_irqrestore(&clockevents_lock, flags); 673} 674#endif 675 676#ifdef CONFIG_SYSFS 677struct bus_type clockevents_subsys = { 678 .name = "clockevents", 679 .dev_name = "clockevent", 680}; 681 682static DEFINE_PER_CPU(struct device, tick_percpu_dev); 683static struct tick_device *tick_get_tick_dev(struct device *dev); 684 685static ssize_t sysfs_show_current_tick_dev(struct device *dev, 686 struct device_attribute *attr, 687 char *buf) 688{ 689 struct tick_device *td; 690 ssize_t count = 0; 691 692 raw_spin_lock_irq(&clockevents_lock); 693 td = tick_get_tick_dev(dev); 694 if (td && td->evtdev) 695 count = snprintf(buf, PAGE_SIZE, "%s\n", td->evtdev->name); 696 raw_spin_unlock_irq(&clockevents_lock); 697 return count; 698} 699static DEVICE_ATTR(current_device, 0444, sysfs_show_current_tick_dev, NULL); 700 701/* We don't support the abomination of removable broadcast devices */ 702static ssize_t sysfs_unbind_tick_dev(struct device *dev, 703 struct device_attribute *attr, 704 const char *buf, size_t count) 705{ 706 char name[CS_NAME_LEN]; 707 ssize_t ret = sysfs_get_uname(buf, name, count); 708 struct clock_event_device *ce; 709 710 if (ret < 0) 711 return ret; 712 713 ret = -ENODEV; 714 mutex_lock(&clockevents_mutex); 715 raw_spin_lock_irq(&clockevents_lock); 716 list_for_each_entry(ce, &clockevent_devices, list) { 717 if (!strcmp(ce->name, name)) { 718 ret = __clockevents_try_unbind(ce, dev->id); 719 break; 720 } 721 } 722 raw_spin_unlock_irq(&clockevents_lock); 723 /* 724 * We hold clockevents_mutex, so ce can't go away 725 */ 726 if (ret == -EAGAIN) 727 ret = clockevents_unbind(ce, dev->id); 728 mutex_unlock(&clockevents_mutex); 729 return ret ? ret : count; 730} 731static DEVICE_ATTR(unbind_device, 0200, NULL, sysfs_unbind_tick_dev); 732 733#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST 734static struct device tick_bc_dev = { 735 .init_name = "broadcast", 736 .id = 0, 737 .bus = &clockevents_subsys, 738}; 739 740static struct tick_device *tick_get_tick_dev(struct device *dev) 741{ 742 return dev == &tick_bc_dev ? tick_get_broadcast_device() : 743 &per_cpu(tick_cpu_device, dev->id); 744} 745 746static __init int tick_broadcast_init_sysfs(void) 747{ 748 int err = device_register(&tick_bc_dev); 749 750 if (!err) 751 err = device_create_file(&tick_bc_dev, &dev_attr_current_device); 752 return err; 753} 754#else 755static struct tick_device *tick_get_tick_dev(struct device *dev) 756{ 757 return &per_cpu(tick_cpu_device, dev->id); 758} 759static inline int tick_broadcast_init_sysfs(void) { return 0; } 760#endif 761 762static int __init tick_init_sysfs(void) 763{ 764 int cpu; 765 766 for_each_possible_cpu(cpu) { 767 struct device *dev = &per_cpu(tick_percpu_dev, cpu); 768 int err; 769 770 dev->id = cpu; 771 dev->bus = &clockevents_subsys; 772 err = device_register(dev); 773 if (!err) 774 err = device_create_file(dev, &dev_attr_current_device); 775 if (!err) 776 err = device_create_file(dev, &dev_attr_unbind_device); 777 if (err) 778 return err; 779 } 780 return tick_broadcast_init_sysfs(); 781} 782 783static int __init clockevents_init_sysfs(void) 784{ 785 int err = subsys_system_register(&clockevents_subsys, NULL); 786 787 if (!err) 788 err = tick_init_sysfs(); 789 return err; 790} 791device_initcall(clockevents_init_sysfs); 792#endif /* SYSFS */ 793