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