drivers/cpuidle/cpuidle.c

   1 /*
   2  * cpuidle.c - core cpuidle infrastructure
   3  *
   4  * (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
   5  *               Shaohua Li <shaohua.li@intel.com>
   6  *               Adam Belay <abelay@novell.com>
   7  *
   8  * This code is licenced under the GPL.
   9  */
  10
  11 #include <linux/clockchips.h>
  12 #include <linux/kernel.h>
  13 #include <linux/mutex.h>
  14 #include <linux/sched.h>
  15 #include <linux/notifier.h>
  16 #include <linux/pm_qos.h>
  17 #include <linux/cpu.h>
  18 #include <linux/cpuidle.h>
  19 #include <linux/ktime.h>
  20 #include <linux/hrtimer.h>
  21 #include <linux/module.h>
  22 #include <linux/suspend.h>
  23 #include <linux/tick.h>
  24 #include <trace/events/power.h>
  25
  26 #include "cpuidle.h"
  27
  28 DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
  29 DEFINE_PER_CPU(struct cpuidle_device, cpuidle_dev);
  30
  31 DEFINE_MUTEX(cpuidle_lock);
  32 LIST_HEAD(cpuidle_detected_devices);
  33
  34 static int enabled_devices;
  35 static int off __read_mostly;
  36 static int initialized __read_mostly;
  37
  38 int cpuidle_disabled(void)
  39 {
  40         return off;
  41 }
  42 void disable_cpuidle(void)
  43 {
  44         off = 1;
  45 }
  46
  47 bool cpuidle_not_available(struct cpuidle_driver *drv,
  48                            struct cpuidle_device *dev)
  49 {
  50         return off || !initialized || !drv || !dev || !dev->enabled;
  51 }
  52
  53 /**
  54  * cpuidle_play_dead - cpu off-lining
  55  *
  56  * Returns in case of an error or no driver
  57  */
  58 int cpuidle_play_dead(void)
  59 {
  60         struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
  61         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
  62         int i;
  63
  64         if (!drv)
  65                 return -ENODEV;
  66
  67         /* Find lowest-power state that supports long-term idle */
  68         for (i = drv->state_count - 1; i >= 0; i--)
  69                 if (drv->states[i].enter_dead)
  70                         return drv->states[i].enter_dead(dev, i);
  71
  72         return -ENODEV;
  73 }
  74
  75 static int find_deepest_state(struct cpuidle_driver *drv,
  76                               struct cpuidle_device *dev,
  77                               unsigned int max_latency,
  78                               unsigned int forbidden_flags,
  79                               bool freeze)
  80 {
  81         unsigned int latency_req = 0;
  82         int i, ret = 0;
  83
  84         for (i = 1; i < drv->state_count; i++) {
  85                 struct cpuidle_state *s = &drv->states[i];
  86                 struct cpuidle_state_usage *su = &dev->states_usage[i];
  87
  88                 if (s->disabled || su->disable || s->exit_latency <= latency_req
  89                     || s->exit_latency > max_latency
  90                     || (s->flags & forbidden_flags)
  91                     || (freeze && !s->enter_freeze))
  92                         continue;
  93
  94                 latency_req = s->exit_latency;
  95                 ret = i;
  96         }
  97         return ret;
  98 }
  99
 100 #ifdef CONFIG_SUSPEND
 101 /**
 102  * cpuidle_find_deepest_state - Find the deepest available idle state.
 103  * @drv: cpuidle driver for the given CPU.
 104  * @dev: cpuidle device for the given CPU.
 105  */
 106 int cpuidle_find_deepest_state(struct cpuidle_driver *drv,
 107                                struct cpuidle_device *dev)
 108 {
 109         return find_deepest_state(drv, dev, UINT_MAX, 0, false);
 110 }
 111
 112 static void enter_freeze_proper(struct cpuidle_driver *drv,
 113                                 struct cpuidle_device *dev, int index)
 114 {
 115         /*
 116          * trace_suspend_resume() called by tick_freeze() for the last CPU
 117          * executing it contains RCU usage regarded as invalid in the idle
 118          * context, so tell RCU about that.
 119          */
 120         RCU_NONIDLE(tick_freeze());
 121         /*
 122          * The state used here cannot be a "coupled" one, because the "coupled"
 123          * cpuidle mechanism enables interrupts and doing that with timekeeping
 124          * suspended is generally unsafe.
 125          */
 126         stop_critical_timings();
 127         drv->states[index].enter_freeze(dev, drv, index);
 128         WARN_ON(!irqs_disabled());
 129         /*
 130          * timekeeping_resume() that will be called by tick_unfreeze() for the
 131          * first CPU executing it calls functions containing RCU read-side
 132          * critical sections, so tell RCU about that.
 133          */
 134         RCU_NONIDLE(tick_unfreeze());
 135         start_critical_timings();
 136 }
 137
 138 /**
 139  * cpuidle_enter_freeze - Enter an idle state suitable for suspend-to-idle.
 140  * @drv: cpuidle driver for the given CPU.
 141  * @dev: cpuidle device for the given CPU.
 142  *
 143  * If there are states with the ->enter_freeze callback, find the deepest of
 144  * them and enter it with frozen tick.
 145  */
 146 int cpuidle_enter_freeze(struct cpuidle_driver *drv, struct cpuidle_device *dev)
 147 {
 148         int index;
 149
 150         /*
 151          * Find the deepest state with ->enter_freeze present, which guarantees
 152          * that interrupts won't be enabled when it exits and allows the tick to
 153          * be frozen safely.
 154          */
 155         index = find_deepest_state(drv, dev, UINT_MAX, 0, true);
 156         if (index > 0)
 157                 enter_freeze_proper(drv, dev, index);
 158
 159         return index;
 160 }
 161 #endif /* CONFIG_SUSPEND */
 162
 163 /**
 164  * cpuidle_enter_state - enter the state and update stats
 165  * @dev: cpuidle device for this cpu
 166  * @drv: cpuidle driver for this cpu
 167  * @index: index into the states table in @drv of the state to enter
 168  */
 169 int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
 170                         int index)
 171 {
 172         int entered_state;
 173
 174         struct cpuidle_state *target_state = &drv->states[index];
 175         bool broadcast = !!(target_state->flags & CPUIDLE_FLAG_TIMER_STOP);
 176         ktime_t time_start, time_end;
 177         s64 diff;
 178
 179         /*
 180          * Tell the time framework to switch to a broadcast timer because our
 181          * local timer will be shut down.  If a local timer is used from another
 182          * CPU as a broadcast timer, this call may fail if it is not available.
 183          */
 184         if (broadcast && tick_broadcast_enter()) {
 185                 index = find_deepest_state(drv, dev, target_state->exit_latency,
 186                                            CPUIDLE_FLAG_TIMER_STOP, false);
 187                 if (index < 0) {
 188                         default_idle_call();
 189                         return -EBUSY;
 190                 }
 191                 target_state = &drv->states[index];
 192         }
 193
 194         /* Take note of the planned idle state. */
 195         sched_idle_set_state(target_state);
 196
 197         trace_cpu_idle_rcuidle(index, dev->cpu);
 198         time_start = ns_to_ktime(local_clock());
 199
 200         stop_critical_timings();
 201         entered_state = target_state->enter(dev, drv, index);
 202         start_critical_timings();
 203
 204         time_end = ns_to_ktime(local_clock());
 205         trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
 206
 207         /* The cpu is no longer idle or about to enter idle. */
 208         sched_idle_set_state(NULL);
 209
 210         if (broadcast) {
 211                 if (WARN_ON_ONCE(!irqs_disabled()))
 212                         local_irq_disable();
 213
 214                 tick_broadcast_exit();
 215         }
 216
 217         if (!cpuidle_state_is_coupled(drv, index))
 218                 local_irq_enable();
 219
 220         diff = ktime_us_delta(time_end, time_start);
 221         if (diff > INT_MAX)
 222                 diff = INT_MAX;
 223
 224         dev->last_residency = (int) diff;
 225
 226         if (entered_state >= 0) {
 227                 /* Update cpuidle counters */
 228                 /* This can be moved to within driver enter routine
 229                  * but that results in multiple copies of same code.
 230                  */
 231                 dev->states_usage[entered_state].time += dev->last_residency;
 232                 dev->states_usage[entered_state].usage++;
 233         } else {
 234                 dev->last_residency = 0;
 235         }
 236
 237         return entered_state;
 238 }
 239
 240 /**
 241  * cpuidle_select - ask the cpuidle framework to choose an idle state
 242  *
 243  * @drv: the cpuidle driver
 244  * @dev: the cpuidle device
 245  *
 246  * Returns the index of the idle state.  The return value must not be negative.
 247  */
 248 int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
 249 {
 250         return cpuidle_curr_governor->select(drv, dev);
 251 }
 252
 253 /**
 254  * cpuidle_enter - enter into the specified idle state
 255  *
 256  * @drv:   the cpuidle driver tied with the cpu
 257  * @dev:   the cpuidle device
 258  * @index: the index in the idle state table
 259  *
 260  * Returns the index in the idle state, < 0 in case of error.
 261  * The error code depends on the backend driver
 262  */
 263 int cpuidle_enter(struct cpuidle_driver *drv, struct cpuidle_device *dev,
 264                   int index)
 265 {
 266         if (cpuidle_state_is_coupled(drv, index))
 267                 return cpuidle_enter_state_coupled(dev, drv, index);
 268         return cpuidle_enter_state(dev, drv, index);
 269 }
 270
 271 /**
 272  * cpuidle_reflect - tell the underlying governor what was the state
 273  * we were in
 274  *
 275  * @dev  : the cpuidle device
 276  * @index: the index in the idle state table
 277  *
 278  */
 279 void cpuidle_reflect(struct cpuidle_device *dev, int index)
 280 {
 281         if (cpuidle_curr_governor->reflect && index >= 0)
 282                 cpuidle_curr_governor->reflect(dev, index);
 283 }
 284
 285 /**
 286  * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
 287  */
 288 void cpuidle_install_idle_handler(void)
 289 {
 290         if (enabled_devices) {
 291                 /* Make sure all changes finished before we switch to new idle */
 292                 smp_wmb();
 293                 initialized = 1;
 294         }
 295 }
 296
 297 /**
 298  * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
 299  */
 300 void cpuidle_uninstall_idle_handler(void)
 301 {
 302         if (enabled_devices) {
 303                 initialized = 0;
 304                 wake_up_all_idle_cpus();
 305         }
 306
 307         /*
 308          * Make sure external observers (such as the scheduler)
 309          * are done looking at pointed idle states.
 310          */
 311         synchronize_rcu();
 312 }
 313
 314 /**
 315  * cpuidle_pause_and_lock - temporarily disables CPUIDLE
 316  */
 317 void cpuidle_pause_and_lock(void)
 318 {
 319         mutex_lock(&cpuidle_lock);
 320         cpuidle_uninstall_idle_handler();
 321 }
 322
 323 EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
 324
 325 /**
 326  * cpuidle_resume_and_unlock - resumes CPUIDLE operation
 327  */
 328 void cpuidle_resume_and_unlock(void)
 329 {
 330         cpuidle_install_idle_handler();
 331         mutex_unlock(&cpuidle_lock);
 332 }
 333
 334 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
 335
 336 /* Currently used in suspend/resume path to suspend cpuidle */
 337 void cpuidle_pause(void)
 338 {
 339         mutex_lock(&cpuidle_lock);
 340         cpuidle_uninstall_idle_handler();
 341         mutex_unlock(&cpuidle_lock);
 342 }
 343
 344 /* Currently used in suspend/resume path to resume cpuidle */
 345 void cpuidle_resume(void)
 346 {
 347         mutex_lock(&cpuidle_lock);
 348         cpuidle_install_idle_handler();
 349         mutex_unlock(&cpuidle_lock);
 350 }
 351
 352 /**
 353  * cpuidle_enable_device - enables idle PM for a CPU
 354  * @dev: the CPU
 355  *
 356  * This function must be called between cpuidle_pause_and_lock and
 357  * cpuidle_resume_and_unlock when used externally.
 358  */
 359 int cpuidle_enable_device(struct cpuidle_device *dev)
 360 {
 361         int ret;
 362         struct cpuidle_driver *drv;
 363
 364         if (!dev)
 365                 return -EINVAL;
 366
 367         if (dev->enabled)
 368                 return 0;
 369
 370         drv = cpuidle_get_cpu_driver(dev);
 371
 372         if (!drv || !cpuidle_curr_governor)
 373                 return -EIO;
 374
 375         if (!dev->registered)
 376                 return -EINVAL;
 377
 378         ret = cpuidle_add_device_sysfs(dev);
 379         if (ret)
 380                 return ret;
 381
 382         if (cpuidle_curr_governor->enable &&
 383             (ret = cpuidle_curr_governor->enable(drv, dev)))
 384                 goto fail_sysfs;
 385
 386         smp_wmb();
 387
 388         dev->enabled = 1;
 389
 390         enabled_devices++;
 391         return 0;
 392
 393 fail_sysfs:
 394         cpuidle_remove_device_sysfs(dev);
 395
 396         return ret;
 397 }
 398
 399 EXPORT_SYMBOL_GPL(cpuidle_enable_device);
 400
 401 /**
 402  * cpuidle_disable_device - disables idle PM for a CPU
 403  * @dev: the CPU
 404  *
 405  * This function must be called between cpuidle_pause_and_lock and
 406  * cpuidle_resume_and_unlock when used externally.
 407  */
 408 void cpuidle_disable_device(struct cpuidle_device *dev)
 409 {
 410         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 411
 412         if (!dev || !dev->enabled)
 413                 return;
 414
 415         if (!drv || !cpuidle_curr_governor)
 416                 return;
 417
 418         dev->enabled = 0;
 419
 420         if (cpuidle_curr_governor->disable)
 421                 cpuidle_curr_governor->disable(drv, dev);
 422
 423         cpuidle_remove_device_sysfs(dev);
 424         enabled_devices--;
 425 }
 426
 427 EXPORT_SYMBOL_GPL(cpuidle_disable_device);
 428
 429 static void __cpuidle_unregister_device(struct cpuidle_device *dev)
 430 {
 431         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 432
 433         list_del(&dev->device_list);
 434         per_cpu(cpuidle_devices, dev->cpu) = NULL;
 435         module_put(drv->owner);
 436
 437         dev->registered = 0;
 438 }
 439
 440 static void __cpuidle_device_init(struct cpuidle_device *dev)
 441 {
 442         memset(dev->states_usage, 0, sizeof(dev->states_usage));
 443         dev->last_residency = 0;
 444 }
 445
 446 /**
 447  * __cpuidle_register_device - internal register function called before register
 448  * and enable routines
 449  * @dev: the cpu
 450  *
 451  * cpuidle_lock mutex must be held before this is called
 452  */
 453 static int __cpuidle_register_device(struct cpuidle_device *dev)
 454 {
 455         int ret;
 456         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 457
 458         if (!try_module_get(drv->owner))
 459                 return -EINVAL;
 460
 461         per_cpu(cpuidle_devices, dev->cpu) = dev;
 462         list_add(&dev->device_list, &cpuidle_detected_devices);
 463
 464         ret = cpuidle_coupled_register_device(dev);
 465         if (ret)
 466                 __cpuidle_unregister_device(dev);
 467         else
 468                 dev->registered = 1;
 469
 470         return ret;
 471 }
 472
 473 /**
 474  * cpuidle_register_device - registers a CPU's idle PM feature
 475  * @dev: the cpu
 476  */
 477 int cpuidle_register_device(struct cpuidle_device *dev)
 478 {
 479         int ret = -EBUSY;
 480
 481         if (!dev)
 482                 return -EINVAL;
 483
 484         mutex_lock(&cpuidle_lock);
 485
 486         if (dev->registered)
 487                 goto out_unlock;
 488
 489         __cpuidle_device_init(dev);
 490
 491         ret = __cpuidle_register_device(dev);
 492         if (ret)
 493                 goto out_unlock;
 494
 495         ret = cpuidle_add_sysfs(dev);
 496         if (ret)
 497                 goto out_unregister;
 498
 499         ret = cpuidle_enable_device(dev);
 500         if (ret)
 501                 goto out_sysfs;
 502
 503         cpuidle_install_idle_handler();
 504
 505 out_unlock:
 506         mutex_unlock(&cpuidle_lock);
 507
 508         return ret;
 509
 510 out_sysfs:
 511         cpuidle_remove_sysfs(dev);
 512 out_unregister:
 513         __cpuidle_unregister_device(dev);
 514         goto out_unlock;
 515 }
 516
 517 EXPORT_SYMBOL_GPL(cpuidle_register_device);
 518
 519 /**
 520  * cpuidle_unregister_device - unregisters a CPU's idle PM feature
 521  * @dev: the cpu
 522  */
 523 void cpuidle_unregister_device(struct cpuidle_device *dev)
 524 {
 525         if (!dev || dev->registered == 0)
 526                 return;
 527
 528         cpuidle_pause_and_lock();
 529
 530         cpuidle_disable_device(dev);
 531
 532         cpuidle_remove_sysfs(dev);
 533
 534         __cpuidle_unregister_device(dev);
 535
 536         cpuidle_coupled_unregister_device(dev);
 537
 538         cpuidle_resume_and_unlock();
 539 }
 540
 541 EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
 542
 543 /**
 544  * cpuidle_unregister: unregister a driver and the devices. This function
 545  * can be used only if the driver has been previously registered through
 546  * the cpuidle_register function.
 547  *
 548  * @drv: a valid pointer to a struct cpuidle_driver
 549  */
 550 void cpuidle_unregister(struct cpuidle_driver *drv)
 551 {
 552         int cpu;
 553         struct cpuidle_device *device;
 554
 555         for_each_cpu(cpu, drv->cpumask) {
 556                 device = &per_cpu(cpuidle_dev, cpu);
 557                 cpuidle_unregister_device(device);
 558         }
 559
 560         cpuidle_unregister_driver(drv);
 561 }
 562 EXPORT_SYMBOL_GPL(cpuidle_unregister);
 563
 564 /**
 565  * cpuidle_register: registers the driver and the cpu devices with the
 566  * coupled_cpus passed as parameter. This function is used for all common
 567  * initialization pattern there are in the arch specific drivers. The
 568  * devices is globally defined in this file.
 569  *
 570  * @drv         : a valid pointer to a struct cpuidle_driver
 571  * @coupled_cpus: a cpumask for the coupled states
 572  *
 573  * Returns 0 on success, < 0 otherwise
 574  */
 575 int cpuidle_register(struct cpuidle_driver *drv,
 576                      const struct cpumask *const coupled_cpus)
 577 {
 578         int ret, cpu;
 579         struct cpuidle_device *device;
 580
 581         ret = cpuidle_register_driver(drv);
 582         if (ret) {
 583                 pr_err("failed to register cpuidle driver\n");
 584                 return ret;
 585         }
 586
 587         for_each_cpu(cpu, drv->cpumask) {
 588                 device = &per_cpu(cpuidle_dev, cpu);
 589                 device->cpu = cpu;
 590
 591 #ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
 592                 /*
 593                  * On multiplatform for ARM, the coupled idle states could be
 594                  * enabled in the kernel even if the cpuidle driver does not
 595                  * use it. Note, coupled_cpus is a struct copy.
 596                  */
 597                 if (coupled_cpus)
 598                         device->coupled_cpus = *coupled_cpus;
 599 #endif
 600                 ret = cpuidle_register_device(device);
 601                 if (!ret)
 602                         continue;
 603
 604                 pr_err("Failed to register cpuidle device for cpu%d\n", cpu);
 605
 606                 cpuidle_unregister(drv);
 607                 break;
 608         }
 609
 610         return ret;
 611 }
 612 EXPORT_SYMBOL_GPL(cpuidle_register);
 613
 614 #ifdef CONFIG_SMP
 615
 616 /*
 617  * This function gets called when a part of the kernel has a new latency
 618  * requirement.  This means we need to get all processors out of their C-state,
 619  * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
 620  * wakes them all right up.
 621  */
 622 static int cpuidle_latency_notify(struct notifier_block *b,
 623                 unsigned long l, void *v)
 624 {
 625         wake_up_all_idle_cpus();
 626         return NOTIFY_OK;
 627 }
 628
 629 static struct notifier_block cpuidle_latency_notifier = {
 630         .notifier_call = cpuidle_latency_notify,
 631 };
 632
 633 static inline void latency_notifier_init(struct notifier_block *n)
 634 {
 635         pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
 636 }
 637
 638 #else /* CONFIG_SMP */
 639
 640 #define latency_notifier_init(x) do { } while (0)
 641
 642 #endif /* CONFIG_SMP */
 643
 644 /**
 645  * cpuidle_init - core initializer
 646  */
 647 static int __init cpuidle_init(void)
 648 {
 649         int ret;
 650
 651         if (cpuidle_disabled())
 652                 return -ENODEV;
 653
 654         ret = cpuidle_add_interface(cpu_subsys.dev_root);
 655         if (ret)
 656                 return ret;
 657
 658         latency_notifier_init(&cpuidle_latency_notifier);
 659
 660         return 0;
 661 }
 662
 663 module_param(off, int, 0444);
 664 core_initcall(cpuidle_init);