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
 122         if (off)
 123                 return -ENODEV;
 124
 125         if (!initialized)
 126                 return -ENODEV;
 127
 128         /* check if the device is ready */
 129         if (!dev || !dev->enabled)
 130                 return -EBUSY;
 131
 132         drv = cpuidle_get_cpu_driver(dev);
 133
 134         /* ask the governor for the next state */
 135         next_state = cpuidle_curr_governor->select(drv, dev);
 136         if (need_resched()) {
 137                 dev->last_residency = 0;
 138                 /* give the governor an opportunity to reflect on the outcome */
 139                 if (cpuidle_curr_governor->reflect)
 140                         cpuidle_curr_governor->reflect(dev, next_state);
 141                 local_irq_enable();
 142                 return 0;
 143         }
 144
 145         trace_cpu_idle_rcuidle(next_state, dev->cpu);
 146
 147         if (drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP)
 148                 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER,
 149                                    &dev->cpu);
 150
 151         if (cpuidle_state_is_coupled(dev, drv, next_state))
 152                 entered_state = cpuidle_enter_state_coupled(dev, drv,
 153                                                             next_state);
 154         else
 155                 entered_state = cpuidle_enter_state(dev, drv, next_state);
 156
 157         if (drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP)
 158                 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT,
 159                                    &dev->cpu);
 160
 161         trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
 162
 163         /* give the governor an opportunity to reflect on the outcome */
 164         if (cpuidle_curr_governor->reflect)
 165                 cpuidle_curr_governor->reflect(dev, entered_state);
 166
 167         return 0;
 168 }
 169
 170 /**
 171  * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
 172  */
 173 void cpuidle_install_idle_handler(void)
 174 {
 175         if (enabled_devices) {
 176                 /* Make sure all changes finished before we switch to new idle */
 177                 smp_wmb();
 178                 initialized = 1;
 179         }
 180 }
 181
 182 /**
 183  * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
 184  */
 185 void cpuidle_uninstall_idle_handler(void)
 186 {
 187         if (enabled_devices) {
 188                 initialized = 0;
 189                 kick_all_cpus_sync();
 190         }
 191 }
 192
 193 /**
 194  * cpuidle_pause_and_lock - temporarily disables CPUIDLE
 195  */
 196 void cpuidle_pause_and_lock(void)
 197 {
 198         mutex_lock(&cpuidle_lock);
 199         cpuidle_uninstall_idle_handler();
 200 }
 201
 202 EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
 203
 204 /**
 205  * cpuidle_resume_and_unlock - resumes CPUIDLE operation
 206  */
 207 void cpuidle_resume_and_unlock(void)
 208 {
 209         cpuidle_install_idle_handler();
 210         mutex_unlock(&cpuidle_lock);
 211 }
 212
 213 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
 214
 215 /* Currently used in suspend/resume path to suspend cpuidle */
 216 void cpuidle_pause(void)
 217 {
 218         mutex_lock(&cpuidle_lock);
 219         cpuidle_uninstall_idle_handler();
 220         mutex_unlock(&cpuidle_lock);
 221 }
 222
 223 /* Currently used in suspend/resume path to resume cpuidle */
 224 void cpuidle_resume(void)
 225 {
 226         mutex_lock(&cpuidle_lock);
 227         cpuidle_install_idle_handler();
 228         mutex_unlock(&cpuidle_lock);
 229 }
 230
 231 #ifdef CONFIG_ARCH_HAS_CPU_RELAX
 232 static int poll_idle(struct cpuidle_device *dev,
 233                 struct cpuidle_driver *drv, int index)
 234 {
 235         ktime_t t1, t2;
 236         s64 diff;
 237
 238         t1 = ktime_get();
 239         local_irq_enable();
 240         while (!need_resched())
 241                 cpu_relax();
 242
 243         t2 = ktime_get();
 244         diff = ktime_to_us(ktime_sub(t2, t1));
 245         if (diff > INT_MAX)
 246                 diff = INT_MAX;
 247
 248         dev->last_residency = (int) diff;
 249
 250         return index;
 251 }
 252
 253 static void poll_idle_init(struct cpuidle_driver *drv)
 254 {
 255         struct cpuidle_state *state = &drv->states[0];
 256
 257         snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
 258         snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
 259         state->exit_latency = 0;
 260         state->target_residency = 0;
 261         state->power_usage = -1;
 262         state->flags = 0;
 263         state->enter = poll_idle;
 264         state->disabled = false;
 265 }
 266 #else
 267 static void poll_idle_init(struct cpuidle_driver *drv) {}
 268 #endif /* CONFIG_ARCH_HAS_CPU_RELAX */
 269
 270 /**
 271  * cpuidle_enable_device - enables idle PM for a CPU
 272  * @dev: the CPU
 273  *
 274  * This function must be called between cpuidle_pause_and_lock and
 275  * cpuidle_resume_and_unlock when used externally.
 276  */
 277 int cpuidle_enable_device(struct cpuidle_device *dev)
 278 {
 279         int ret;
 280         struct cpuidle_driver *drv;
 281
 282         if (!dev)
 283                 return -EINVAL;
 284
 285         if (dev->enabled)
 286                 return 0;
 287
 288         drv = cpuidle_get_cpu_driver(dev);
 289
 290         if (!drv || !cpuidle_curr_governor)
 291                 return -EIO;
 292
 293         if (!dev->registered)
 294                 return -EINVAL;
 295
 296         if (!dev->state_count)
 297                 dev->state_count = drv->state_count;
 298
 299         poll_idle_init(drv);
 300
 301         ret = cpuidle_add_device_sysfs(dev);
 302         if (ret)
 303                 return ret;
 304
 305         if (cpuidle_curr_governor->enable &&
 306             (ret = cpuidle_curr_governor->enable(drv, dev)))
 307                 goto fail_sysfs;
 308
 309         smp_wmb();
 310
 311         dev->enabled = 1;
 312
 313         enabled_devices++;
 314         return 0;
 315
 316 fail_sysfs:
 317         cpuidle_remove_device_sysfs(dev);
 318
 319         return ret;
 320 }
 321
 322 EXPORT_SYMBOL_GPL(cpuidle_enable_device);
 323
 324 /**
 325  * cpuidle_disable_device - disables idle PM for a CPU
 326  * @dev: the CPU
 327  *
 328  * This function must be called between cpuidle_pause_and_lock and
 329  * cpuidle_resume_and_unlock when used externally.
 330  */
 331 void cpuidle_disable_device(struct cpuidle_device *dev)
 332 {
 333         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 334
 335         if (!dev || !dev->enabled)
 336                 return;
 337
 338         if (!drv || !cpuidle_curr_governor)
 339                 return;
 340
 341         dev->enabled = 0;
 342
 343         if (cpuidle_curr_governor->disable)
 344                 cpuidle_curr_governor->disable(drv, dev);
 345
 346         cpuidle_remove_device_sysfs(dev);
 347         enabled_devices--;
 348 }
 349
 350 EXPORT_SYMBOL_GPL(cpuidle_disable_device);
 351
 352 static void __cpuidle_unregister_device(struct cpuidle_device *dev)
 353 {
 354         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 355
 356         list_del(&dev->device_list);
 357         per_cpu(cpuidle_devices, dev->cpu) = NULL;
 358         module_put(drv->owner);
 359 }
 360
 361 static int __cpuidle_device_init(struct cpuidle_device *dev)
 362 {
 363         memset(dev->states_usage, 0, sizeof(dev->states_usage));
 364         dev->last_residency = 0;
 365
 366         return 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                 return ret;
 391         }
 392
 393         dev->registered = 1;
 394         return 0;
 395 }
 396
 397 /**
 398  * cpuidle_register_device - registers a CPU's idle PM feature
 399  * @dev: the cpu
 400  */
 401 int cpuidle_register_device(struct cpuidle_device *dev)
 402 {
 403         int ret = -EBUSY;
 404
 405         if (!dev)
 406                 return -EINVAL;
 407
 408         mutex_lock(&cpuidle_lock);
 409
 410         if (dev->registered)
 411                 goto out_unlock;
 412
 413         ret = __cpuidle_device_init(dev);
 414         if (ret)
 415                 goto out_unlock;
 416
 417         ret = __cpuidle_register_device(dev);
 418         if (ret)
 419                 goto out_unlock;
 420
 421         ret = cpuidle_add_sysfs(dev);
 422         if (ret)
 423                 goto out_unregister;
 424
 425         ret = cpuidle_enable_device(dev);
 426         if (ret)
 427                 goto out_sysfs;
 428
 429         cpuidle_install_idle_handler();
 430
 431 out_unlock:
 432         mutex_unlock(&cpuidle_lock);
 433
 434         return ret;
 435
 436 out_sysfs:
 437         cpuidle_remove_sysfs(dev);
 438 out_unregister:
 439         __cpuidle_unregister_device(dev);
 440         goto out_unlock;
 441 }
 442
 443 EXPORT_SYMBOL_GPL(cpuidle_register_device);
 444
 445 /**
 446  * cpuidle_unregister_device - unregisters a CPU's idle PM feature
 447  * @dev: the cpu
 448  */
 449 void cpuidle_unregister_device(struct cpuidle_device *dev)
 450 {
 451         if (!dev || dev->registered == 0)
 452                 return;
 453
 454         cpuidle_pause_and_lock();
 455
 456         cpuidle_disable_device(dev);
 457
 458         cpuidle_remove_sysfs(dev);
 459
 460         __cpuidle_unregister_device(dev);
 461
 462         cpuidle_coupled_unregister_device(dev);
 463
 464         cpuidle_resume_and_unlock();
 465 }
 466
 467 EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
 468
 469 /**
 470  * cpuidle_unregister: unregister a driver and the devices. This function
 471  * can be used only if the driver has been previously registered through
 472  * the cpuidle_register function.
 473  *
 474  * @drv: a valid pointer to a struct cpuidle_driver
 475  */
 476 void cpuidle_unregister(struct cpuidle_driver *drv)
 477 {
 478         int cpu;
 479         struct cpuidle_device *device;
 480
 481         for_each_cpu(cpu, drv->cpumask) {
 482                 device = &per_cpu(cpuidle_dev, cpu);
 483                 cpuidle_unregister_device(device);
 484         }
 485
 486         cpuidle_unregister_driver(drv);
 487 }
 488 EXPORT_SYMBOL_GPL(cpuidle_unregister);
 489
 490 /**
 491  * cpuidle_register: registers the driver and the cpu devices with the
 492  * coupled_cpus passed as parameter. This function is used for all common
 493  * initialization pattern there are in the arch specific drivers. The
 494  * devices is globally defined in this file.
 495  *
 496  * @drv         : a valid pointer to a struct cpuidle_driver
 497  * @coupled_cpus: a cpumask for the coupled states
 498  *
 499  * Returns 0 on success, < 0 otherwise
 500  */
 501 int cpuidle_register(struct cpuidle_driver *drv,
 502                      const struct cpumask *const coupled_cpus)
 503 {
 504         int ret, cpu;
 505         struct cpuidle_device *device;
 506
 507         ret = cpuidle_register_driver(drv);
 508         if (ret) {
 509                 pr_err("failed to register cpuidle driver\n");
 510                 return ret;
 511         }
 512
 513         for_each_cpu(cpu, drv->cpumask) {
 514                 device = &per_cpu(cpuidle_dev, cpu);
 515                 device->cpu = cpu;
 516
 517 #ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
 518                 /*
 519                  * On multiplatform for ARM, the coupled idle states could
 520                  * enabled in the kernel even if the cpuidle driver does not
 521                  * use it. Note, coupled_cpus is a struct copy.
 522                  */
 523                 if (coupled_cpus)
 524                         device->coupled_cpus = *coupled_cpus;
 525 #endif
 526                 ret = cpuidle_register_device(device);
 527                 if (!ret)
 528                         continue;
 529
 530                 pr_err("Failed to register cpuidle device for cpu%d\n", cpu);
 531
 532                 cpuidle_unregister(drv);
 533                 break;
 534         }
 535
 536         return ret;
 537 }
 538 EXPORT_SYMBOL_GPL(cpuidle_register);
 539
 540 #ifdef CONFIG_SMP
 541
 542 static void smp_callback(void *v)
 543 {
 544         /* we already woke the CPU up, nothing more to do */
 545 }
 546
 547 /*
 548  * This function gets called when a part of the kernel has a new latency
 549  * requirement.  This means we need to get all processors out of their C-state,
 550  * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
 551  * wakes them all right up.
 552  */
 553 static int cpuidle_latency_notify(struct notifier_block *b,
 554                 unsigned long l, void *v)
 555 {
 556         smp_call_function(smp_callback, NULL, 1);
 557         return NOTIFY_OK;
 558 }
 559
 560 static struct notifier_block cpuidle_latency_notifier = {
 561         .notifier_call = cpuidle_latency_notify,
 562 };
 563
 564 static inline void latency_notifier_init(struct notifier_block *n)
 565 {
 566         pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
 567 }
 568
 569 #else /* CONFIG_SMP */
 570
 571 #define latency_notifier_init(x) do { } while (0)
 572
 573 #endif /* CONFIG_SMP */
 574
 575 /**
 576  * cpuidle_init - core initializer
 577  */
 578 static int __init cpuidle_init(void)
 579 {
 580         int ret;
 581
 582         if (cpuidle_disabled())
 583                 return -ENODEV;
 584
 585         ret = cpuidle_add_interface(cpu_subsys.dev_root);
 586         if (ret)
 587                 return ret;
 588
 589         latency_notifier_init(&cpuidle_latency_notifier);
 590
 591         return 0;
 592 }
 593
 594 module_param(off, int, 0444);
 595 core_initcall(cpuidle_init);