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         u64 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 = local_clock();
 199
 200         stop_critical_timings();
 201         entered_state = target_state->enter(dev, drv, index);
 202         start_critical_timings();
 203
 204         time_end = 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, entered_state))
 218                 local_irq_enable();
 219
 220         /*
 221          * local_clock() returns the time in nanosecond, let's shift
 222          * by 10 (divide by 1024) to have microsecond based time.
 223          */
 224         diff = (time_end - time_start) >> 10;
 225         if (diff > INT_MAX)
 226                 diff = INT_MAX;
 227
 228         dev->last_residency = (int) diff;
 229
 230         if (entered_state >= 0) {
 231                 /* Update cpuidle counters */
 232                 /* This can be moved to within driver enter routine
 233                  * but that results in multiple copies of same code.
 234                  */
 235                 dev->states_usage[entered_state].time += dev->last_residency;
 236                 dev->states_usage[entered_state].usage++;
 237         } else {
 238                 dev->last_residency = 0;
 239         }
 240
 241         return entered_state;
 242 }
 243
 244 /**
 245  * cpuidle_select - ask the cpuidle framework to choose an idle state
 246  *
 247  * @drv: the cpuidle driver
 248  * @dev: the cpuidle device
 249  *
 250  * Returns the index of the idle state.  The return value must not be negative.
 251  */
 252 int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
 253 {
 254         return cpuidle_curr_governor->select(drv, dev);
 255 }
 256
 257 /**
 258  * cpuidle_enter - enter into the specified idle state
 259  *
 260  * @drv:   the cpuidle driver tied with the cpu
 261  * @dev:   the cpuidle device
 262  * @index: the index in the idle state table
 263  *
 264  * Returns the index in the idle state, < 0 in case of error.
 265  * The error code depends on the backend driver
 266  */
 267 int cpuidle_enter(struct cpuidle_driver *drv, struct cpuidle_device *dev,
 268                   int index)
 269 {
 270         if (cpuidle_state_is_coupled(drv, index))
 271                 return cpuidle_enter_state_coupled(dev, drv, index);
 272         return cpuidle_enter_state(dev, drv, index);
 273 }
 274
 275 /**
 276  * cpuidle_reflect - tell the underlying governor what was the state
 277  * we were in
 278  *
 279  * @dev  : the cpuidle device
 280  * @index: the index in the idle state table
 281  *
 282  */
 283 void cpuidle_reflect(struct cpuidle_device *dev, int index)
 284 {
 285         if (cpuidle_curr_governor->reflect && index >= 0)
 286                 cpuidle_curr_governor->reflect(dev, index);
 287 }
 288
 289 /**
 290  * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
 291  */
 292 void cpuidle_install_idle_handler(void)
 293 {
 294         if (enabled_devices) {
 295                 /* Make sure all changes finished before we switch to new idle */
 296                 smp_wmb();
 297                 initialized = 1;
 298         }
 299 }
 300
 301 /**
 302  * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
 303  */
 304 void cpuidle_uninstall_idle_handler(void)
 305 {
 306         if (enabled_devices) {
 307                 initialized = 0;
 308                 wake_up_all_idle_cpus();
 309         }
 310
 311         /*
 312          * Make sure external observers (such as the scheduler)
 313          * are done looking at pointed idle states.
 314          */
 315         synchronize_rcu();
 316 }
 317
 318 /**
 319  * cpuidle_pause_and_lock - temporarily disables CPUIDLE
 320  */
 321 void cpuidle_pause_and_lock(void)
 322 {
 323         mutex_lock(&cpuidle_lock);
 324         cpuidle_uninstall_idle_handler();
 325 }
 326
 327 EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
 328
 329 /**
 330  * cpuidle_resume_and_unlock - resumes CPUIDLE operation
 331  */
 332 void cpuidle_resume_and_unlock(void)
 333 {
 334         cpuidle_install_idle_handler();
 335         mutex_unlock(&cpuidle_lock);
 336 }
 337
 338 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
 339
 340 /* Currently used in suspend/resume path to suspend cpuidle */
 341 void cpuidle_pause(void)
 342 {
 343         mutex_lock(&cpuidle_lock);
 344         cpuidle_uninstall_idle_handler();
 345         mutex_unlock(&cpuidle_lock);
 346 }
 347
 348 /* Currently used in suspend/resume path to resume cpuidle */
 349 void cpuidle_resume(void)
 350 {
 351         mutex_lock(&cpuidle_lock);
 352         cpuidle_install_idle_handler();
 353         mutex_unlock(&cpuidle_lock);
 354 }
 355
 356 /**
 357  * cpuidle_enable_device - enables idle PM for a CPU
 358  * @dev: the CPU
 359  *
 360  * This function must be called between cpuidle_pause_and_lock and
 361  * cpuidle_resume_and_unlock when used externally.
 362  */
 363 int cpuidle_enable_device(struct cpuidle_device *dev)
 364 {
 365         int ret;
 366         struct cpuidle_driver *drv;
 367
 368         if (!dev)
 369                 return -EINVAL;
 370
 371         if (dev->enabled)
 372                 return 0;
 373
 374         drv = cpuidle_get_cpu_driver(dev);
 375
 376         if (!drv || !cpuidle_curr_governor)
 377                 return -EIO;
 378
 379         if (!dev->registered)
 380                 return -EINVAL;
 381
 382         ret = cpuidle_add_device_sysfs(dev);
 383         if (ret)
 384                 return ret;
 385
 386         if (cpuidle_curr_governor->enable &&
 387             (ret = cpuidle_curr_governor->enable(drv, dev)))
 388                 goto fail_sysfs;
 389
 390         smp_wmb();
 391
 392         dev->enabled = 1;
 393
 394         enabled_devices++;
 395         return 0;
 396
 397 fail_sysfs:
 398         cpuidle_remove_device_sysfs(dev);
 399
 400         return ret;
 401 }
 402
 403 EXPORT_SYMBOL_GPL(cpuidle_enable_device);
 404
 405 /**
 406  * cpuidle_disable_device - disables idle PM for a CPU
 407  * @dev: the CPU
 408  *
 409  * This function must be called between cpuidle_pause_and_lock and
 410  * cpuidle_resume_and_unlock when used externally.
 411  */
 412 void cpuidle_disable_device(struct cpuidle_device *dev)
 413 {
 414         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 415
 416         if (!dev || !dev->enabled)
 417                 return;
 418
 419         if (!drv || !cpuidle_curr_governor)
 420                 return;
 421
 422         dev->enabled = 0;
 423
 424         if (cpuidle_curr_governor->disable)
 425                 cpuidle_curr_governor->disable(drv, dev);
 426
 427         cpuidle_remove_device_sysfs(dev);
 428         enabled_devices--;
 429 }
 430
 431 EXPORT_SYMBOL_GPL(cpuidle_disable_device);
 432
 433 static void __cpuidle_unregister_device(struct cpuidle_device *dev)
 434 {
 435         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 436
 437         list_del(&dev->device_list);
 438         per_cpu(cpuidle_devices, dev->cpu) = NULL;
 439         module_put(drv->owner);
 440
 441         dev->registered = 0;
 442 }
 443
 444 static void __cpuidle_device_init(struct cpuidle_device *dev)
 445 {
 446         memset(dev->states_usage, 0, sizeof(dev->states_usage));
 447         dev->last_residency = 0;
 448 }
 449
 450 /**
 451  * __cpuidle_register_device - internal register function called before register
 452  * and enable routines
 453  * @dev: the cpu
 454  *
 455  * cpuidle_lock mutex must be held before this is called
 456  */
 457 static int __cpuidle_register_device(struct cpuidle_device *dev)
 458 {
 459         int ret;
 460         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 461
 462         if (!try_module_get(drv->owner))
 463                 return -EINVAL;
 464
 465         per_cpu(cpuidle_devices, dev->cpu) = dev;
 466         list_add(&dev->device_list, &cpuidle_detected_devices);
 467
 468         ret = cpuidle_coupled_register_device(dev);
 469         if (ret)
 470                 __cpuidle_unregister_device(dev);
 471         else
 472                 dev->registered = 1;
 473
 474         return ret;
 475 }
 476
 477 /**
 478  * cpuidle_register_device - registers a CPU's idle PM feature
 479  * @dev: the cpu
 480  */
 481 int cpuidle_register_device(struct cpuidle_device *dev)
 482 {
 483         int ret = -EBUSY;
 484
 485         if (!dev)
 486                 return -EINVAL;
 487
 488         mutex_lock(&cpuidle_lock);
 489
 490         if (dev->registered)
 491                 goto out_unlock;
 492
 493         __cpuidle_device_init(dev);
 494
 495         ret = __cpuidle_register_device(dev);
 496         if (ret)
 497                 goto out_unlock;
 498
 499         ret = cpuidle_add_sysfs(dev);
 500         if (ret)
 501                 goto out_unregister;
 502
 503         ret = cpuidle_enable_device(dev);
 504         if (ret)
 505                 goto out_sysfs;
 506
 507         cpuidle_install_idle_handler();
 508
 509 out_unlock:
 510         mutex_unlock(&cpuidle_lock);
 511
 512         return ret;
 513
 514 out_sysfs:
 515         cpuidle_remove_sysfs(dev);
 516 out_unregister:
 517         __cpuidle_unregister_device(dev);
 518         goto out_unlock;
 519 }
 520
 521 EXPORT_SYMBOL_GPL(cpuidle_register_device);
 522
 523 /**
 524  * cpuidle_unregister_device - unregisters a CPU's idle PM feature
 525  * @dev: the cpu
 526  */
 527 void cpuidle_unregister_device(struct cpuidle_device *dev)
 528 {
 529         if (!dev || dev->registered == 0)
 530                 return;
 531
 532         cpuidle_pause_and_lock();
 533
 534         cpuidle_disable_device(dev);
 535
 536         cpuidle_remove_sysfs(dev);
 537
 538         __cpuidle_unregister_device(dev);
 539
 540         cpuidle_coupled_unregister_device(dev);
 541
 542         cpuidle_resume_and_unlock();
 543 }
 544
 545 EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
 546
 547 /**
 548  * cpuidle_unregister: unregister a driver and the devices. This function
 549  * can be used only if the driver has been previously registered through
 550  * the cpuidle_register function.
 551  *
 552  * @drv: a valid pointer to a struct cpuidle_driver
 553  */
 554 void cpuidle_unregister(struct cpuidle_driver *drv)
 555 {
 556         int cpu;
 557         struct cpuidle_device *device;
 558
 559         for_each_cpu(cpu, drv->cpumask) {
 560                 device = &per_cpu(cpuidle_dev, cpu);
 561                 cpuidle_unregister_device(device);
 562         }
 563
 564         cpuidle_unregister_driver(drv);
 565 }
 566 EXPORT_SYMBOL_GPL(cpuidle_unregister);
 567
 568 /**
 569  * cpuidle_register: registers the driver and the cpu devices with the
 570  * coupled_cpus passed as parameter. This function is used for all common
 571  * initialization pattern there are in the arch specific drivers. The
 572  * devices is globally defined in this file.
 573  *
 574  * @drv         : a valid pointer to a struct cpuidle_driver
 575  * @coupled_cpus: a cpumask for the coupled states
 576  *
 577  * Returns 0 on success, < 0 otherwise
 578  */
 579 int cpuidle_register(struct cpuidle_driver *drv,
 580                      const struct cpumask *const coupled_cpus)
 581 {
 582         int ret, cpu;
 583         struct cpuidle_device *device;
 584
 585         ret = cpuidle_register_driver(drv);
 586         if (ret) {
 587                 pr_err("failed to register cpuidle driver\n");
 588                 return ret;
 589         }
 590
 591         for_each_cpu(cpu, drv->cpumask) {
 592                 device = &per_cpu(cpuidle_dev, cpu);
 593                 device->cpu = cpu;
 594
 595 #ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
 596                 /*
 597                  * On multiplatform for ARM, the coupled idle states could be
 598                  * enabled in the kernel even if the cpuidle driver does not
 599                  * use it. Note, coupled_cpus is a struct copy.
 600                  */
 601                 if (coupled_cpus)
 602                         device->coupled_cpus = *coupled_cpus;
 603 #endif
 604                 ret = cpuidle_register_device(device);
 605                 if (!ret)
 606                         continue;
 607
 608                 pr_err("Failed to register cpuidle device for cpu%d\n", cpu);
 609
 610                 cpuidle_unregister(drv);
 611                 break;
 612         }
 613
 614         return ret;
 615 }
 616 EXPORT_SYMBOL_GPL(cpuidle_register);
 617
 618 #ifdef CONFIG_SMP
 619
 620 /*
 621  * This function gets called when a part of the kernel has a new latency
 622  * requirement.  This means we need to get all processors out of their C-state,
 623  * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
 624  * wakes them all right up.
 625  */
 626 static int cpuidle_latency_notify(struct notifier_block *b,
 627                 unsigned long l, void *v)
 628 {
 629         wake_up_all_idle_cpus();
 630         return NOTIFY_OK;
 631 }
 632
 633 static struct notifier_block cpuidle_latency_notifier = {
 634         .notifier_call = cpuidle_latency_notify,
 635 };
 636
 637 static inline void latency_notifier_init(struct notifier_block *n)
 638 {
 639         pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
 640 }
 641
 642 #else /* CONFIG_SMP */
 643
 644 #define latency_notifier_init(x) do { } while (0)
 645
 646 #endif /* CONFIG_SMP */
 647
 648 /**
 649  * cpuidle_init - core initializer
 650  */
 651 static int __init cpuidle_init(void)
 652 {
 653         int ret;
 654
 655         if (cpuidle_disabled())
 656                 return -ENODEV;
 657
 658         ret = cpuidle_add_interface(cpu_subsys.dev_root);
 659         if (ret)
 660                 return ret;
 661
 662         latency_notifier_init(&cpuidle_latency_notifier);
 663
 664         return 0;
 665 }
 666
 667 module_param(off, int, 0444);
 668 core_initcall(cpuidle_init);