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         if (!dev->state_count)
 301                 dev->state_count = drv->state_count;
 302
 303         ret = cpuidle_add_device_sysfs(dev);
 304         if (ret)
 305                 return ret;
 306
 307         if (cpuidle_curr_governor->enable &&
 308             (ret = cpuidle_curr_governor->enable(drv, dev)))
 309                 goto fail_sysfs;
 310
 311         smp_wmb();
 312
 313         dev->enabled = 1;
 314
 315         enabled_devices++;
 316         return 0;
 317
 318 fail_sysfs:
 319         cpuidle_remove_device_sysfs(dev);
 320
 321         return ret;
 322 }
 323
 324 EXPORT_SYMBOL_GPL(cpuidle_enable_device);
 325
 326 /**
 327  * cpuidle_disable_device - disables idle PM for a CPU
 328  * @dev: the CPU
 329  *
 330  * This function must be called between cpuidle_pause_and_lock and
 331  * cpuidle_resume_and_unlock when used externally.
 332  */
 333 void cpuidle_disable_device(struct cpuidle_device *dev)
 334 {
 335         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 336
 337         if (!dev || !dev->enabled)
 338                 return;
 339
 340         if (!drv || !cpuidle_curr_governor)
 341                 return;
 342
 343         dev->enabled = 0;
 344
 345         if (cpuidle_curr_governor->disable)
 346                 cpuidle_curr_governor->disable(drv, dev);
 347
 348         cpuidle_remove_device_sysfs(dev);
 349         enabled_devices--;
 350 }
 351
 352 EXPORT_SYMBOL_GPL(cpuidle_disable_device);
 353
 354 static void __cpuidle_unregister_device(struct cpuidle_device *dev)
 355 {
 356         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 357
 358         list_del(&dev->device_list);
 359         per_cpu(cpuidle_devices, dev->cpu) = NULL;
 360         module_put(drv->owner);
 361 }
 362
 363 static void __cpuidle_device_init(struct cpuidle_device *dev)
 364 {
 365         memset(dev->states_usage, 0, sizeof(dev->states_usage));
 366         dev->last_residency = 0;
 367 }
 368
 369 /**
 370  * __cpuidle_register_device - internal register function called before register
 371  * and enable routines
 372  * @dev: the cpu
 373  *
 374  * cpuidle_lock mutex must be held before this is called
 375  */
 376 static int __cpuidle_register_device(struct cpuidle_device *dev)
 377 {
 378         int ret;
 379         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 380
 381         if (!try_module_get(drv->owner))
 382                 return -EINVAL;
 383
 384         per_cpu(cpuidle_devices, dev->cpu) = dev;
 385         list_add(&dev->device_list, &cpuidle_detected_devices);
 386
 387         ret = cpuidle_coupled_register_device(dev);
 388         if (ret)
 389                 __cpuidle_unregister_device(dev);
 390         else
 391                 dev->registered = 1;
 392
 393         return ret;
 394 }
 395
 396 /**
 397  * cpuidle_register_device - registers a CPU's idle PM feature
 398  * @dev: the cpu
 399  */
 400 int cpuidle_register_device(struct cpuidle_device *dev)
 401 {
 402         int ret = -EBUSY;
 403
 404         if (!dev)
 405                 return -EINVAL;
 406
 407         mutex_lock(&cpuidle_lock);
 408
 409         if (dev->registered)
 410                 goto out_unlock;
 411
 412         __cpuidle_device_init(dev);
 413
 414         ret = __cpuidle_register_device(dev);
 415         if (ret)
 416                 goto out_unlock;
 417
 418         ret = cpuidle_add_sysfs(dev);
 419         if (ret)
 420                 goto out_unregister;
 421
 422         ret = cpuidle_enable_device(dev);
 423         if (ret)
 424                 goto out_sysfs;
 425
 426         cpuidle_install_idle_handler();
 427
 428 out_unlock:
 429         mutex_unlock(&cpuidle_lock);
 430
 431         return ret;
 432
 433 out_sysfs:
 434         cpuidle_remove_sysfs(dev);
 435 out_unregister:
 436         __cpuidle_unregister_device(dev);
 437         goto out_unlock;
 438 }
 439
 440 EXPORT_SYMBOL_GPL(cpuidle_register_device);
 441
 442 /**
 443  * cpuidle_unregister_device - unregisters a CPU's idle PM feature
 444  * @dev: the cpu
 445  */
 446 void cpuidle_unregister_device(struct cpuidle_device *dev)
 447 {
 448         if (!dev || dev->registered == 0)
 449                 return;
 450
 451         cpuidle_pause_and_lock();
 452
 453         cpuidle_disable_device(dev);
 454
 455         cpuidle_remove_sysfs(dev);
 456
 457         __cpuidle_unregister_device(dev);
 458
 459         cpuidle_coupled_unregister_device(dev);
 460
 461         cpuidle_resume_and_unlock();
 462 }
 463
 464 EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
 465
 466 /**
 467  * cpuidle_unregister: unregister a driver and the devices. This function
 468  * can be used only if the driver has been previously registered through
 469  * the cpuidle_register function.
 470  *
 471  * @drv: a valid pointer to a struct cpuidle_driver
 472  */
 473 void cpuidle_unregister(struct cpuidle_driver *drv)
 474 {
 475         int cpu;
 476         struct cpuidle_device *device;
 477
 478         for_each_cpu(cpu, drv->cpumask) {
 479                 device = &per_cpu(cpuidle_dev, cpu);
 480                 cpuidle_unregister_device(device);
 481         }
 482
 483         cpuidle_unregister_driver(drv);
 484 }
 485 EXPORT_SYMBOL_GPL(cpuidle_unregister);
 486
 487 /**
 488  * cpuidle_register: registers the driver and the cpu devices with the
 489  * coupled_cpus passed as parameter. This function is used for all common
 490  * initialization pattern there are in the arch specific drivers. The
 491  * devices is globally defined in this file.
 492  *
 493  * @drv         : a valid pointer to a struct cpuidle_driver
 494  * @coupled_cpus: a cpumask for the coupled states
 495  *
 496  * Returns 0 on success, < 0 otherwise
 497  */
 498 int cpuidle_register(struct cpuidle_driver *drv,
 499                      const struct cpumask *const coupled_cpus)
 500 {
 501         int ret, cpu;
 502         struct cpuidle_device *device;
 503
 504         ret = cpuidle_register_driver(drv);
 505         if (ret) {
 506                 pr_err("failed to register cpuidle driver\n");
 507                 return ret;
 508         }
 509
 510         for_each_cpu(cpu, drv->cpumask) {
 511                 device = &per_cpu(cpuidle_dev, cpu);
 512                 device->cpu = cpu;
 513
 514 #ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
 515                 /*
 516                  * On multiplatform for ARM, the coupled idle states could be
 517                  * enabled in the kernel even if the cpuidle driver does not
 518                  * use it. Note, coupled_cpus is a struct copy.
 519                  */
 520                 if (coupled_cpus)
 521                         device->coupled_cpus = *coupled_cpus;
 522 #endif
 523                 ret = cpuidle_register_device(device);
 524                 if (!ret)
 525                         continue;
 526
 527                 pr_err("Failed to register cpuidle device for cpu%d\n", cpu);
 528
 529                 cpuidle_unregister(drv);
 530                 break;
 531         }
 532
 533         return ret;
 534 }
 535 EXPORT_SYMBOL_GPL(cpuidle_register);
 536
 537 #ifdef CONFIG_SMP
 538
 539 /*
 540  * This function gets called when a part of the kernel has a new latency
 541  * requirement.  This means we need to get all processors out of their C-state,
 542  * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
 543  * wakes them all right up.
 544  */
 545 static int cpuidle_latency_notify(struct notifier_block *b,
 546                 unsigned long l, void *v)
 547 {
 548         wake_up_all_idle_cpus();
 549         return NOTIFY_OK;
 550 }
 551
 552 static struct notifier_block cpuidle_latency_notifier = {
 553         .notifier_call = cpuidle_latency_notify,
 554 };
 555
 556 static inline void latency_notifier_init(struct notifier_block *n)
 557 {
 558         pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
 559 }
 560
 561 #else /* CONFIG_SMP */
 562
 563 #define latency_notifier_init(x) do { } while (0)
 564
 565 #endif /* CONFIG_SMP */
 566
 567 /**
 568  * cpuidle_init - core initializer
 569  */
 570 static int __init cpuidle_init(void)
 571 {
 572         int ret;
 573
 574         if (cpuidle_disabled())
 575                 return -ENODEV;
 576
 577         ret = cpuidle_add_interface(cpu_subsys.dev_root);
 578         if (ret)
 579                 return ret;
 580
 581         latency_notifier_init(&cpuidle_latency_notifier);
 582
 583         return 0;
 584 }
 585
 586 module_param(off, int, 0444);
 587 core_initcall(cpuidle_init);