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