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 <trace/events/power.h>
  23
  24 #include "cpuidle.h"
  25
  26 DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
  27 DEFINE_PER_CPU(struct cpuidle_device, cpuidle_dev);
  28
  29 DEFINE_MUTEX(cpuidle_lock);
  30 LIST_HEAD(cpuidle_detected_devices);
  31
  32 static int enabled_devices;
  33 static int off __read_mostly;
  34 static int initialized __read_mostly;
  35 static bool use_deepest_state __read_mostly;
  36
  37 int cpuidle_disabled(void)
  38 {
  39         return off;
  40 }
  41 void disable_cpuidle(void)
  42 {
  43         off = 1;
  44 }
  45
  46 /**
  47  * cpuidle_play_dead - cpu off-lining
  48  *
  49  * Returns in case of an error or no driver
  50  */
  51 int cpuidle_play_dead(void)
  52 {
  53         struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
  54         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
  55         int i;
  56
  57         if (!drv)
  58                 return -ENODEV;
  59
  60         /* Find lowest-power state that supports long-term idle */
  61         for (i = drv->state_count - 1; i >= CPUIDLE_DRIVER_STATE_START; i--)
  62                 if (drv->states[i].enter_dead)
  63                         return drv->states[i].enter_dead(dev, i);
  64
  65         return -ENODEV;
  66 }
  67
  68 /**
  69  * cpuidle_use_deepest_state - Enable/disable the "deepest idle" mode.
  70  * @enable: Whether enable or disable the feature.
  71  *
  72  * If the "deepest idle" mode is enabled, cpuidle will ignore the governor and
  73  * always use the state with the greatest exit latency (out of the states that
  74  * are not disabled).
  75  *
  76  * This function can only be called after cpuidle_pause() to avoid races.
  77  */
  78 void cpuidle_use_deepest_state(bool enable)
  79 {
  80         use_deepest_state = enable;
  81 }
  82
  83 /**
  84  * cpuidle_find_deepest_state - Find the state of the greatest exit latency.
  85  * @drv: cpuidle driver for a given CPU.
  86  * @dev: cpuidle device for a given CPU.
  87  */
  88 static int cpuidle_find_deepest_state(struct cpuidle_driver *drv,
  89                                       struct cpuidle_device *dev)
  90 {
  91         unsigned int latency_req = 0;
  92         int i, ret = CPUIDLE_DRIVER_STATE_START - 1;
  93
  94         for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
  95                 struct cpuidle_state *s = &drv->states[i];
  96                 struct cpuidle_state_usage *su = &dev->states_usage[i];
  97
  98                 if (s->disabled || su->disable || s->exit_latency <= latency_req)
  99                         continue;
 100
 101                 latency_req = s->exit_latency;
 102                 ret = i;
 103         }
 104         return ret;
 105 }
 106
 107 /**
 108  * cpuidle_enter_state - enter the state and update stats
 109  * @dev: cpuidle device for this cpu
 110  * @drv: cpuidle driver for this cpu
 111  * @next_state: index into drv->states of the state to enter
 112  */
 113 int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
 114                         int index)
 115 {
 116         int entered_state;
 117
 118         struct cpuidle_state *target_state = &drv->states[index];
 119         ktime_t time_start, time_end;
 120         s64 diff;
 121
 122         trace_cpu_idle_rcuidle(index, dev->cpu);
 123         time_start = ktime_get();
 124
 125         entered_state = target_state->enter(dev, drv, index);
 126
 127         time_end = ktime_get();
 128         trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
 129
 130         if (!cpuidle_state_is_coupled(dev, drv, entered_state))
 131                 local_irq_enable();
 132
 133         diff = ktime_to_us(ktime_sub(time_end, time_start));
 134         if (diff > INT_MAX)
 135                 diff = INT_MAX;
 136
 137         dev->last_residency = (int) diff;
 138
 139         if (entered_state >= 0) {
 140                 /* Update cpuidle counters */
 141                 /* This can be moved to within driver enter routine
 142                  * but that results in multiple copies of same code.
 143                  */
 144                 dev->states_usage[entered_state].time += dev->last_residency;
 145                 dev->states_usage[entered_state].usage++;
 146         } else {
 147                 dev->last_residency = 0;
 148         }
 149
 150         return entered_state;
 151 }
 152
 153 /**
 154  * cpuidle_select - ask the cpuidle framework to choose an idle state
 155  *
 156  * @drv: the cpuidle driver
 157  * @dev: the cpuidle device
 158  *
 159  * Returns the index of the idle state.
 160  */
 161 int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
 162 {
 163         if (off || !initialized)
 164                 return -ENODEV;
 165
 166         if (!drv || !dev || !dev->enabled)
 167                 return -EBUSY;
 168
 169         if (unlikely(use_deepest_state))
 170                 return cpuidle_find_deepest_state(drv, dev);
 171
 172         return cpuidle_curr_governor->select(drv, dev);
 173 }
 174
 175 /**
 176  * cpuidle_enter - enter into the specified idle state
 177  *
 178  * @drv:   the cpuidle driver tied with the cpu
 179  * @dev:   the cpuidle device
 180  * @index: the index in the idle state table
 181  *
 182  * Returns the index in the idle state, < 0 in case of error.
 183  * The error code depends on the backend driver
 184  */
 185 int cpuidle_enter(struct cpuidle_driver *drv, struct cpuidle_device *dev,
 186                   int index)
 187 {
 188         if (cpuidle_state_is_coupled(dev, drv, index))
 189                 return cpuidle_enter_state_coupled(dev, drv, index);
 190         return cpuidle_enter_state(dev, drv, index);
 191 }
 192
 193 /**
 194  * cpuidle_reflect - tell the underlying governor what was the state
 195  * we were in
 196  *
 197  * @dev  : the cpuidle device
 198  * @index: the index in the idle state table
 199  *
 200  */
 201 void cpuidle_reflect(struct cpuidle_device *dev, int index)
 202 {
 203         if (cpuidle_curr_governor->reflect && !unlikely(use_deepest_state))
 204                 cpuidle_curr_governor->reflect(dev, index);
 205 }
 206
 207 /**
 208  * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
 209  */
 210 void cpuidle_install_idle_handler(void)
 211 {
 212         if (enabled_devices) {
 213                 /* Make sure all changes finished before we switch to new idle */
 214                 smp_wmb();
 215                 initialized = 1;
 216         }
 217 }
 218
 219 /**
 220  * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
 221  */
 222 void cpuidle_uninstall_idle_handler(void)
 223 {
 224         if (enabled_devices) {
 225                 initialized = 0;
 226                 wake_up_all_idle_cpus();
 227         }
 228
 229         /*
 230          * Make sure external observers (such as the scheduler)
 231          * are done looking at pointed idle states.
 232          */
 233         synchronize_rcu();
 234 }
 235
 236 /**
 237  * cpuidle_pause_and_lock - temporarily disables CPUIDLE
 238  */
 239 void cpuidle_pause_and_lock(void)
 240 {
 241         mutex_lock(&cpuidle_lock);
 242         cpuidle_uninstall_idle_handler();
 243 }
 244
 245 EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
 246
 247 /**
 248  * cpuidle_resume_and_unlock - resumes CPUIDLE operation
 249  */
 250 void cpuidle_resume_and_unlock(void)
 251 {
 252         cpuidle_install_idle_handler();
 253         mutex_unlock(&cpuidle_lock);
 254 }
 255
 256 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
 257
 258 /* Currently used in suspend/resume path to suspend cpuidle */
 259 void cpuidle_pause(void)
 260 {
 261         mutex_lock(&cpuidle_lock);
 262         cpuidle_uninstall_idle_handler();
 263         mutex_unlock(&cpuidle_lock);
 264 }
 265
 266 /* Currently used in suspend/resume path to resume cpuidle */
 267 void cpuidle_resume(void)
 268 {
 269         mutex_lock(&cpuidle_lock);
 270         cpuidle_install_idle_handler();
 271         mutex_unlock(&cpuidle_lock);
 272 }
 273
 274 /**
 275  * cpuidle_enable_device - enables idle PM for a CPU
 276  * @dev: the CPU
 277  *
 278  * This function must be called between cpuidle_pause_and_lock and
 279  * cpuidle_resume_and_unlock when used externally.
 280  */
 281 int cpuidle_enable_device(struct cpuidle_device *dev)
 282 {
 283         int ret;
 284         struct cpuidle_driver *drv;
 285
 286         if (!dev)
 287                 return -EINVAL;
 288
 289         if (dev->enabled)
 290                 return 0;
 291
 292         drv = cpuidle_get_cpu_driver(dev);
 293
 294         if (!drv || !cpuidle_curr_governor)
 295                 return -EIO;
 296
 297         if (!dev->registered)
 298                 return -EINVAL;
 299
 300         ret = cpuidle_add_device_sysfs(dev);
 301         if (ret)
 302                 return ret;
 303
 304         if (cpuidle_curr_governor->enable &&
 305             (ret = cpuidle_curr_governor->enable(drv, dev)))
 306                 goto fail_sysfs;
 307
 308         smp_wmb();
 309
 310         dev->enabled = 1;
 311
 312         enabled_devices++;
 313         return 0;
 314
 315 fail_sysfs:
 316         cpuidle_remove_device_sysfs(dev);
 317
 318         return ret;
 319 }
 320
 321 EXPORT_SYMBOL_GPL(cpuidle_enable_device);
 322
 323 /**
 324  * cpuidle_disable_device - disables idle PM for a CPU
 325  * @dev: the CPU
 326  *
 327  * This function must be called between cpuidle_pause_and_lock and
 328  * cpuidle_resume_and_unlock when used externally.
 329  */
 330 void cpuidle_disable_device(struct cpuidle_device *dev)
 331 {
 332         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 333
 334         if (!dev || !dev->enabled)
 335                 return;
 336
 337         if (!drv || !cpuidle_curr_governor)
 338                 return;
 339
 340         dev->enabled = 0;
 341
 342         if (cpuidle_curr_governor->disable)
 343                 cpuidle_curr_governor->disable(drv, dev);
 344
 345         cpuidle_remove_device_sysfs(dev);
 346         enabled_devices--;
 347 }
 348
 349 EXPORT_SYMBOL_GPL(cpuidle_disable_device);
 350
 351 static void __cpuidle_unregister_device(struct cpuidle_device *dev)
 352 {
 353         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 354
 355         list_del(&dev->device_list);
 356         per_cpu(cpuidle_devices, dev->cpu) = NULL;
 357         module_put(drv->owner);
 358 }
 359
 360 static void __cpuidle_device_init(struct cpuidle_device *dev)
 361 {
 362         memset(dev->states_usage, 0, sizeof(dev->states_usage));
 363         dev->last_residency = 0;
 364 }
 365
 366 /**
 367  * __cpuidle_register_device - internal register function called before register
 368  * and enable routines
 369  * @dev: the cpu
 370  *
 371  * cpuidle_lock mutex must be held before this is called
 372  */
 373 static int __cpuidle_register_device(struct cpuidle_device *dev)
 374 {
 375         int ret;
 376         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 377
 378         if (!try_module_get(drv->owner))
 379                 return -EINVAL;
 380
 381         per_cpu(cpuidle_devices, dev->cpu) = dev;
 382         list_add(&dev->device_list, &cpuidle_detected_devices);
 383
 384         ret = cpuidle_coupled_register_device(dev);
 385         if (ret)
 386                 __cpuidle_unregister_device(dev);
 387         else
 388                 dev->registered = 1;
 389
 390         return ret;
 391 }
 392
 393 /**
 394  * cpuidle_register_device - registers a CPU's idle PM feature
 395  * @dev: the cpu
 396  */
 397 int cpuidle_register_device(struct cpuidle_device *dev)
 398 {
 399         int ret = -EBUSY;
 400
 401         if (!dev)
 402                 return -EINVAL;
 403
 404         mutex_lock(&cpuidle_lock);
 405
 406         if (dev->registered)
 407                 goto out_unlock;
 408
 409         __cpuidle_device_init(dev);
 410
 411         ret = __cpuidle_register_device(dev);
 412         if (ret)
 413                 goto out_unlock;
 414
 415         ret = cpuidle_add_sysfs(dev);
 416         if (ret)
 417                 goto out_unregister;
 418
 419         ret = cpuidle_enable_device(dev);
 420         if (ret)
 421                 goto out_sysfs;
 422
 423         cpuidle_install_idle_handler();
 424
 425 out_unlock:
 426         mutex_unlock(&cpuidle_lock);
 427
 428         return ret;
 429
 430 out_sysfs:
 431         cpuidle_remove_sysfs(dev);
 432 out_unregister:
 433         __cpuidle_unregister_device(dev);
 434         goto out_unlock;
 435 }
 436
 437 EXPORT_SYMBOL_GPL(cpuidle_register_device);
 438
 439 /**
 440  * cpuidle_unregister_device - unregisters a CPU's idle PM feature
 441  * @dev: the cpu
 442  */
 443 void cpuidle_unregister_device(struct cpuidle_device *dev)
 444 {
 445         if (!dev || dev->registered == 0)
 446                 return;
 447
 448         cpuidle_pause_and_lock();
 449
 450         cpuidle_disable_device(dev);
 451
 452         cpuidle_remove_sysfs(dev);
 453
 454         __cpuidle_unregister_device(dev);
 455
 456         cpuidle_coupled_unregister_device(dev);
 457
 458         cpuidle_resume_and_unlock();
 459 }
 460
 461 EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
 462
 463 /**
 464  * cpuidle_unregister: unregister a driver and the devices. This function
 465  * can be used only if the driver has been previously registered through
 466  * the cpuidle_register function.
 467  *
 468  * @drv: a valid pointer to a struct cpuidle_driver
 469  */
 470 void cpuidle_unregister(struct cpuidle_driver *drv)
 471 {
 472         int cpu;
 473         struct cpuidle_device *device;
 474
 475         for_each_cpu(cpu, drv->cpumask) {
 476                 device = &per_cpu(cpuidle_dev, cpu);
 477                 cpuidle_unregister_device(device);
 478         }
 479
 480         cpuidle_unregister_driver(drv);
 481 }
 482 EXPORT_SYMBOL_GPL(cpuidle_unregister);
 483
 484 /**
 485  * cpuidle_register: registers the driver and the cpu devices with the
 486  * coupled_cpus passed as parameter. This function is used for all common
 487  * initialization pattern there are in the arch specific drivers. The
 488  * devices is globally defined in this file.
 489  *
 490  * @drv         : a valid pointer to a struct cpuidle_driver
 491  * @coupled_cpus: a cpumask for the coupled states
 492  *
 493  * Returns 0 on success, < 0 otherwise
 494  */
 495 int cpuidle_register(struct cpuidle_driver *drv,
 496                      const struct cpumask *const coupled_cpus)
 497 {
 498         int ret, cpu;
 499         struct cpuidle_device *device;
 500
 501         ret = cpuidle_register_driver(drv);
 502         if (ret) {
 503                 pr_err("failed to register cpuidle driver\n");
 504                 return ret;
 505         }
 506
 507         for_each_cpu(cpu, drv->cpumask) {
 508                 device = &per_cpu(cpuidle_dev, cpu);
 509                 device->cpu = cpu;
 510
 511 #ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
 512                 /*
 513                  * On multiplatform for ARM, the coupled idle states could be
 514                  * enabled in the kernel even if the cpuidle driver does not
 515                  * use it. Note, coupled_cpus is a struct copy.
 516                  */
 517                 if (coupled_cpus)
 518                         device->coupled_cpus = *coupled_cpus;
 519 #endif
 520                 ret = cpuidle_register_device(device);
 521                 if (!ret)
 522                         continue;
 523
 524                 pr_err("Failed to register cpuidle device for cpu%d\n", cpu);
 525
 526                 cpuidle_unregister(drv);
 527                 break;
 528         }
 529
 530         return ret;
 531 }
 532 EXPORT_SYMBOL_GPL(cpuidle_register);
 533
 534 #ifdef CONFIG_SMP
 535
 536 /*
 537  * This function gets called when a part of the kernel has a new latency
 538  * requirement.  This means we need to get all processors out of their C-state,
 539  * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
 540  * wakes them all right up.
 541  */
 542 static int cpuidle_latency_notify(struct notifier_block *b,
 543                 unsigned long l, void *v)
 544 {
 545         wake_up_all_idle_cpus();
 546         return NOTIFY_OK;
 547 }
 548
 549 static struct notifier_block cpuidle_latency_notifier = {
 550         .notifier_call = cpuidle_latency_notify,
 551 };
 552
 553 static inline void latency_notifier_init(struct notifier_block *n)
 554 {
 555         pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
 556 }
 557
 558 #else /* CONFIG_SMP */
 559
 560 #define latency_notifier_init(x) do { } while (0)
 561
 562 #endif /* CONFIG_SMP */
 563
 564 /**
 565  * cpuidle_init - core initializer
 566  */
 567 static int __init cpuidle_init(void)
 568 {
 569         int ret;
 570
 571         if (cpuidle_disabled())
 572                 return -ENODEV;
 573
 574         ret = cpuidle_add_interface(cpu_subsys.dev_root);
 575         if (ret)
 576                 return ret;
 577
 578         latency_notifier_init(&cpuidle_latency_notifier);
 579
 580         return 0;
 581 }
 582
 583 module_param(off, int, 0444);
 584 core_initcall(cpuidle_init);