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
  36 int cpuidle_disabled(void)
  37 {
  38         return off;
  39 }
  40 void disable_cpuidle(void)
  41 {
  42         off = 1;
  43 }
  44
  45 static int __cpuidle_register_device(struct cpuidle_device *dev);
  46
  47 /**
  48  * cpuidle_play_dead - cpu off-lining
  49  *
  50  * Returns in case of an error or no driver
  51  */
  52 int cpuidle_play_dead(void)
  53 {
  54         struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
  55         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
  56         int i;
  57
  58         if (!drv)
  59                 return -ENODEV;
  60
  61         /* Find lowest-power state that supports long-term idle */
  62         for (i = drv->state_count - 1; i >= CPUIDLE_DRIVER_STATE_START; i--)
  63                 if (drv->states[i].enter_dead)
  64                         return drv->states[i].enter_dead(dev, i);
  65
  66         return -ENODEV;
  67 }
  68
  69 /**
  70  * cpuidle_enter_state - enter the state and update stats
  71  * @dev: cpuidle device for this cpu
  72  * @drv: cpuidle driver for this cpu
  73  * @next_state: index into drv->states of the state to enter
  74  */
  75 int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
  76                         int index)
  77 {
  78         int entered_state;
  79
  80         struct cpuidle_state *target_state = &drv->states[index];
  81         ktime_t time_start, time_end;
  82         s64 diff;
  83
  84         time_start = ktime_get();
  85
  86         entered_state = target_state->enter(dev, drv, index);
  87
  88         time_end = ktime_get();
  89
  90         local_irq_enable();
  91
  92         diff = ktime_to_us(ktime_sub(time_end, time_start));
  93         if (diff > INT_MAX)
  94                 diff = INT_MAX;
  95
  96         dev->last_residency = (int) diff;
  97
  98         if (entered_state >= 0) {
  99                 /* Update cpuidle counters */
 100                 /* This can be moved to within driver enter routine
 101                  * but that results in multiple copies of same code.
 102                  */
 103                 dev->states_usage[entered_state].time += dev->last_residency;
 104                 dev->states_usage[entered_state].usage++;
 105         } else {
 106                 dev->last_residency = 0;
 107         }
 108
 109         return entered_state;
 110 }
 111
 112 /**
 113  * cpuidle_idle_call - the main idle loop
 114  *
 115  * NOTE: no locks or semaphores should be used here
 116  * return non-zero on failure
 117  */
 118 int cpuidle_idle_call(void)
 119 {
 120         struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
 121         struct cpuidle_driver *drv;
 122         int next_state, entered_state;
 123
 124         if (off)
 125                 return -ENODEV;
 126
 127         if (!initialized)
 128                 return -ENODEV;
 129
 130         /* check if the device is ready */
 131         if (!dev || !dev->enabled)
 132                 return -EBUSY;
 133
 134         drv = cpuidle_get_cpu_driver(dev);
 135
 136         /* ask the governor for the next state */
 137         next_state = cpuidle_curr_governor->select(drv, dev);
 138         if (need_resched()) {
 139                 dev->last_residency = 0;
 140                 /* give the governor an opportunity to reflect on the outcome */
 141                 if (cpuidle_curr_governor->reflect)
 142                         cpuidle_curr_governor->reflect(dev, next_state);
 143                 local_irq_enable();
 144                 return 0;
 145         }
 146
 147         trace_cpu_idle_rcuidle(next_state, dev->cpu);
 148
 149         if (drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP)
 150                 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER,
 151                                    &dev->cpu);
 152
 153         if (cpuidle_state_is_coupled(dev, drv, next_state))
 154                 entered_state = cpuidle_enter_state_coupled(dev, drv,
 155                                                             next_state);
 156         else
 157                 entered_state = cpuidle_enter_state(dev, drv, next_state);
 158
 159         if (drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP)
 160                 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT,
 161                                    &dev->cpu);
 162
 163         trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
 164
 165         /* give the governor an opportunity to reflect on the outcome */
 166         if (cpuidle_curr_governor->reflect)
 167                 cpuidle_curr_governor->reflect(dev, entered_state);
 168
 169         return 0;
 170 }
 171
 172 /**
 173  * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
 174  */
 175 void cpuidle_install_idle_handler(void)
 176 {
 177         if (enabled_devices) {
 178                 /* Make sure all changes finished before we switch to new idle */
 179                 smp_wmb();
 180                 initialized = 1;
 181         }
 182 }
 183
 184 /**
 185  * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
 186  */
 187 void cpuidle_uninstall_idle_handler(void)
 188 {
 189         if (enabled_devices) {
 190                 initialized = 0;
 191                 kick_all_cpus_sync();
 192         }
 193 }
 194
 195 /**
 196  * cpuidle_pause_and_lock - temporarily disables CPUIDLE
 197  */
 198 void cpuidle_pause_and_lock(void)
 199 {
 200         mutex_lock(&cpuidle_lock);
 201         cpuidle_uninstall_idle_handler();
 202 }
 203
 204 EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
 205
 206 /**
 207  * cpuidle_resume_and_unlock - resumes CPUIDLE operation
 208  */
 209 void cpuidle_resume_and_unlock(void)
 210 {
 211         cpuidle_install_idle_handler();
 212         mutex_unlock(&cpuidle_lock);
 213 }
 214
 215 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
 216
 217 /* Currently used in suspend/resume path to suspend cpuidle */
 218 void cpuidle_pause(void)
 219 {
 220         mutex_lock(&cpuidle_lock);
 221         cpuidle_uninstall_idle_handler();
 222         mutex_unlock(&cpuidle_lock);
 223 }
 224
 225 /* Currently used in suspend/resume path to resume cpuidle */
 226 void cpuidle_resume(void)
 227 {
 228         mutex_lock(&cpuidle_lock);
 229         cpuidle_install_idle_handler();
 230         mutex_unlock(&cpuidle_lock);
 231 }
 232
 233 #ifdef CONFIG_ARCH_HAS_CPU_RELAX
 234 static int poll_idle(struct cpuidle_device *dev,
 235                 struct cpuidle_driver *drv, int index)
 236 {
 237         ktime_t t1, t2;
 238         s64 diff;
 239
 240         t1 = ktime_get();
 241         local_irq_enable();
 242         while (!need_resched())
 243                 cpu_relax();
 244
 245         t2 = ktime_get();
 246         diff = ktime_to_us(ktime_sub(t2, t1));
 247         if (diff > INT_MAX)
 248                 diff = INT_MAX;
 249
 250         dev->last_residency = (int) diff;
 251
 252         return index;
 253 }
 254
 255 static void poll_idle_init(struct cpuidle_driver *drv)
 256 {
 257         struct cpuidle_state *state = &drv->states[0];
 258
 259         snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
 260         snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
 261         state->exit_latency = 0;
 262         state->target_residency = 0;
 263         state->power_usage = -1;
 264         state->flags = 0;
 265         state->enter = poll_idle;
 266         state->disabled = false;
 267 }
 268 #else
 269 static void poll_idle_init(struct cpuidle_driver *drv) {}
 270 #endif /* CONFIG_ARCH_HAS_CPU_RELAX */
 271
 272 /**
 273  * cpuidle_enable_device - enables idle PM for a CPU
 274  * @dev: the CPU
 275  *
 276  * This function must be called between cpuidle_pause_and_lock and
 277  * cpuidle_resume_and_unlock when used externally.
 278  */
 279 int cpuidle_enable_device(struct cpuidle_device *dev)
 280 {
 281         int ret, i;
 282         struct cpuidle_driver *drv;
 283
 284         if (!dev)
 285                 return -EINVAL;
 286
 287         if (dev->enabled)
 288                 return 0;
 289
 290         drv = cpuidle_get_cpu_driver(dev);
 291
 292         if (!drv || !cpuidle_curr_governor)
 293                 return -EIO;
 294
 295         if (!dev->state_count)
 296                 dev->state_count = drv->state_count;
 297
 298         if (dev->registered == 0) {
 299                 ret = __cpuidle_register_device(dev);
 300                 if (ret)
 301                         return ret;
 302         }
 303
 304         poll_idle_init(drv);
 305
 306         ret = cpuidle_add_device_sysfs(dev);
 307         if (ret)
 308                 return ret;
 309
 310         if (cpuidle_curr_governor->enable &&
 311             (ret = cpuidle_curr_governor->enable(drv, dev)))
 312                 goto fail_sysfs;
 313
 314         for (i = 0; i < dev->state_count; i++) {
 315                 dev->states_usage[i].usage = 0;
 316                 dev->states_usage[i].time = 0;
 317         }
 318         dev->last_residency = 0;
 319
 320         smp_wmb();
 321
 322         dev->enabled = 1;
 323
 324         enabled_devices++;
 325         return 0;
 326
 327 fail_sysfs:
 328         cpuidle_remove_device_sysfs(dev);
 329
 330         return ret;
 331 }
 332
 333 EXPORT_SYMBOL_GPL(cpuidle_enable_device);
 334
 335 /**
 336  * cpuidle_disable_device - disables idle PM for a CPU
 337  * @dev: the CPU
 338  *
 339  * This function must be called between cpuidle_pause_and_lock and
 340  * cpuidle_resume_and_unlock when used externally.
 341  */
 342 void cpuidle_disable_device(struct cpuidle_device *dev)
 343 {
 344         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 345
 346         if (!dev || !dev->enabled)
 347                 return;
 348
 349         if (!drv || !cpuidle_curr_governor)
 350                 return;
 351
 352         dev->enabled = 0;
 353
 354         if (cpuidle_curr_governor->disable)
 355                 cpuidle_curr_governor->disable(drv, dev);
 356
 357         cpuidle_remove_device_sysfs(dev);
 358         enabled_devices--;
 359 }
 360
 361 EXPORT_SYMBOL_GPL(cpuidle_disable_device);
 362
 363 /**
 364  * __cpuidle_register_device - internal register function called before register
 365  * and enable routines
 366  * @dev: the cpu
 367  *
 368  * cpuidle_lock mutex must be held before this is called
 369  */
 370 static int __cpuidle_register_device(struct cpuidle_device *dev)
 371 {
 372         int ret;
 373         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 374
 375         if (!try_module_get(drv->owner))
 376                 return -EINVAL;
 377
 378         per_cpu(cpuidle_devices, dev->cpu) = dev;
 379         list_add(&dev->device_list, &cpuidle_detected_devices);
 380         ret = cpuidle_add_sysfs(dev);
 381         if (ret)
 382                 goto err_sysfs;
 383
 384         ret = cpuidle_coupled_register_device(dev);
 385         if (ret)
 386                 goto err_coupled;
 387
 388         dev->registered = 1;
 389         return 0;
 390
 391 err_coupled:
 392         cpuidle_remove_sysfs(dev);
 393 err_sysfs:
 394         list_del(&dev->device_list);
 395         per_cpu(cpuidle_devices, dev->cpu) = NULL;
 396         module_put(drv->owner);
 397         return ret;
 398 }
 399
 400 /**
 401  * cpuidle_register_device - registers a CPU's idle PM feature
 402  * @dev: the cpu
 403  */
 404 int cpuidle_register_device(struct cpuidle_device *dev)
 405 {
 406         int ret;
 407
 408         if (!dev)
 409                 return -EINVAL;
 410
 411         mutex_lock(&cpuidle_lock);
 412
 413         if ((ret = __cpuidle_register_device(dev))) {
 414                 mutex_unlock(&cpuidle_lock);
 415                 return ret;
 416         }
 417
 418         cpuidle_enable_device(dev);
 419         cpuidle_install_idle_handler();
 420
 421         mutex_unlock(&cpuidle_lock);
 422
 423         return 0;
 424
 425 }
 426
 427 EXPORT_SYMBOL_GPL(cpuidle_register_device);
 428
 429 /**
 430  * cpuidle_unregister_device - unregisters a CPU's idle PM feature
 431  * @dev: the cpu
 432  */
 433 void cpuidle_unregister_device(struct cpuidle_device *dev)
 434 {
 435         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 436
 437         if (dev->registered == 0)
 438                 return;
 439
 440         cpuidle_pause_and_lock();
 441
 442         cpuidle_disable_device(dev);
 443
 444         cpuidle_remove_sysfs(dev);
 445         list_del(&dev->device_list);
 446         per_cpu(cpuidle_devices, dev->cpu) = NULL;
 447
 448         cpuidle_coupled_unregister_device(dev);
 449
 450         cpuidle_resume_and_unlock();
 451
 452         module_put(drv->owner);
 453 }
 454
 455 EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
 456
 457 /**
 458  * cpuidle_unregister: unregister a driver and the devices. This function
 459  * can be used only if the driver has been previously registered through
 460  * the cpuidle_register function.
 461  *
 462  * @drv: a valid pointer to a struct cpuidle_driver
 463  */
 464 void cpuidle_unregister(struct cpuidle_driver *drv)
 465 {
 466         int cpu;
 467         struct cpuidle_device *device;
 468
 469         for_each_possible_cpu(cpu) {
 470                 device = &per_cpu(cpuidle_dev, cpu);
 471                 cpuidle_unregister_device(device);
 472         }
 473
 474         cpuidle_unregister_driver(drv);
 475 }
 476 EXPORT_SYMBOL_GPL(cpuidle_unregister);
 477
 478 /**
 479  * cpuidle_register: registers the driver and the cpu devices with the
 480  * coupled_cpus passed as parameter. This function is used for all common
 481  * initialization pattern there are in the arch specific drivers. The
 482  * devices is globally defined in this file.
 483  *
 484  * @drv         : a valid pointer to a struct cpuidle_driver
 485  * @coupled_cpus: a cpumask for the coupled states
 486  *
 487  * Returns 0 on success, < 0 otherwise
 488  */
 489 int cpuidle_register(struct cpuidle_driver *drv,
 490                      const struct cpumask *const coupled_cpus)
 491 {
 492         int ret, cpu;
 493         struct cpuidle_device *device;
 494
 495         ret = cpuidle_register_driver(drv);
 496         if (ret) {
 497                 pr_err("failed to register cpuidle driver\n");
 498                 return ret;
 499         }
 500
 501         for_each_possible_cpu(cpu) {
 502                 device = &per_cpu(cpuidle_dev, cpu);
 503                 device->cpu = cpu;
 504
 505 #ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
 506                 /*
 507                  * On multiplatform for ARM, the coupled idle states could
 508                  * enabled in the kernel even if the cpuidle driver does not
 509                  * use it. Note, coupled_cpus is a struct copy.
 510                  */
 511                 if (coupled_cpus)
 512                         device->coupled_cpus = *coupled_cpus;
 513 #endif
 514                 ret = cpuidle_register_device(device);
 515                 if (!ret)
 516                         continue;
 517
 518                 pr_err("Failed to register cpuidle device for cpu%d\n", cpu);
 519
 520                 cpuidle_unregister(drv);
 521                 break;
 522         }
 523
 524         return ret;
 525 }
 526 EXPORT_SYMBOL_GPL(cpuidle_register);
 527
 528 #ifdef CONFIG_SMP
 529
 530 static void smp_callback(void *v)
 531 {
 532         /* we already woke the CPU up, nothing more to do */
 533 }
 534
 535 /*
 536  * This function gets called when a part of the kernel has a new latency
 537  * requirement.  This means we need to get all processors out of their C-state,
 538  * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
 539  * wakes them all right up.
 540  */
 541 static int cpuidle_latency_notify(struct notifier_block *b,
 542                 unsigned long l, void *v)
 543 {
 544         smp_call_function(smp_callback, NULL, 1);
 545         return NOTIFY_OK;
 546 }
 547
 548 static struct notifier_block cpuidle_latency_notifier = {
 549         .notifier_call = cpuidle_latency_notify,
 550 };
 551
 552 static inline void latency_notifier_init(struct notifier_block *n)
 553 {
 554         pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
 555 }
 556
 557 #else /* CONFIG_SMP */
 558
 559 #define latency_notifier_init(x) do { } while (0)
 560
 561 #endif /* CONFIG_SMP */
 562
 563 /**
 564  * cpuidle_init - core initializer
 565  */
 566 static int __init cpuidle_init(void)
 567 {
 568         int ret;
 569
 570         if (cpuidle_disabled())
 571                 return -ENODEV;
 572
 573         ret = cpuidle_add_interface(cpu_subsys.dev_root);
 574         if (ret)
 575                 return ret;
 576
 577         latency_notifier_init(&cpuidle_latency_notifier);
 578
 579         return 0;
 580 }
 581
 582 module_param(off, int, 0444);
 583 core_initcall(cpuidle_init);