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/kernel.h>
  12 #include <linux/mutex.h>
  13 #include <linux/sched.h>
  14 #include <linux/notifier.h>
  15 #include <linux/pm_qos.h>
  16 #include <linux/cpu.h>
  17 #include <linux/cpuidle.h>
  18 #include <linux/ktime.h>
  19 #include <linux/hrtimer.h>
  20 #include <linux/module.h>
  21 #include <trace/events/power.h>
  22
  23 #include "cpuidle.h"
  24
  25 DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
  26
  27 DEFINE_MUTEX(cpuidle_lock);
  28 LIST_HEAD(cpuidle_detected_devices);
  29
  30 static int enabled_devices;
  31 static int off __read_mostly;
  32 static int initialized __read_mostly;
  33
  34 int cpuidle_disabled(void)
  35 {
  36         return off;
  37 }
  38 void disable_cpuidle(void)
  39 {
  40         off = 1;
  41 }
  42
  43 static int __cpuidle_register_device(struct cpuidle_device *dev);
  44
  45 static inline int cpuidle_enter(struct cpuidle_device *dev,
  46                                 struct cpuidle_driver *drv, int index)
  47 {
  48         struct cpuidle_state *target_state = &drv->states[index];
  49         return target_state->enter(dev, drv, index);
  50 }
  51
  52 static inline int cpuidle_enter_tk(struct cpuidle_device *dev,
  53                                struct cpuidle_driver *drv, int index)
  54 {
  55         return cpuidle_wrap_enter(dev, drv, index, cpuidle_enter);
  56 }
  57
  58 typedef int (*cpuidle_enter_t)(struct cpuidle_device *dev,
  59                                struct cpuidle_driver *drv, int index);
  60
  61 static cpuidle_enter_t cpuidle_enter_ops;
  62
  63 /**
  64  * cpuidle_play_dead - cpu off-lining
  65  *
  66  * Returns in case of an error or no driver
  67  */
  68 int cpuidle_play_dead(void)
  69 {
  70         struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
  71         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
  72         int i, dead_state = -1;
  73         int power_usage = -1;
  74
  75         if (!drv)
  76                 return -ENODEV;
  77
  78         /* Find lowest-power state that supports long-term idle */
  79         for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
  80                 struct cpuidle_state *s = &drv->states[i];
  81
  82                 if (s->power_usage < power_usage && s->enter_dead) {
  83                         power_usage = s->power_usage;
  84                         dead_state = i;
  85                 }
  86         }
  87
  88         if (dead_state != -1)
  89                 return drv->states[dead_state].enter_dead(dev, dead_state);
  90
  91         return -ENODEV;
  92 }
  93
  94 /**
  95  * cpuidle_enter_state - enter the state and update stats
  96  * @dev: cpuidle device for this cpu
  97  * @drv: cpuidle driver for this cpu
  98  * @next_state: index into drv->states of the state to enter
  99  */
 100 int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
 101                 int next_state)
 102 {
 103         int entered_state;
 104
 105         entered_state = cpuidle_enter_ops(dev, drv, next_state);
 106
 107         if (entered_state >= 0) {
 108                 /* Update cpuidle counters */
 109                 /* This can be moved to within driver enter routine
 110                  * but that results in multiple copies of same code.
 111                  */
 112                 dev->states_usage[entered_state].time +=
 113                                 (unsigned long long)dev->last_residency;
 114                 dev->states_usage[entered_state].usage++;
 115         } else {
 116                 dev->last_residency = 0;
 117         }
 118
 119         return entered_state;
 120 }
 121
 122 /**
 123  * cpuidle_idle_call - the main idle loop
 124  *
 125  * NOTE: no locks or semaphores should be used here
 126  * return non-zero on failure
 127  */
 128 int cpuidle_idle_call(void)
 129 {
 130         struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
 131         struct cpuidle_driver *drv;
 132         int next_state, entered_state;
 133
 134         if (off)
 135                 return -ENODEV;
 136
 137         if (!initialized)
 138                 return -ENODEV;
 139
 140         /* check if the device is ready */
 141         if (!dev || !dev->enabled)
 142                 return -EBUSY;
 143
 144         drv = cpuidle_get_cpu_driver(dev);
 145
 146         /* ask the governor for the next state */
 147         next_state = cpuidle_curr_governor->select(drv, dev);
 148         if (need_resched()) {
 149                 dev->last_residency = 0;
 150                 /* give the governor an opportunity to reflect on the outcome */
 151                 if (cpuidle_curr_governor->reflect)
 152                         cpuidle_curr_governor->reflect(dev, next_state);
 153                 local_irq_enable();
 154                 return 0;
 155         }
 156
 157         trace_power_start_rcuidle(POWER_CSTATE, next_state, dev->cpu);
 158         trace_cpu_idle_rcuidle(next_state, dev->cpu);
 159
 160         if (cpuidle_state_is_coupled(dev, drv, next_state))
 161                 entered_state = cpuidle_enter_state_coupled(dev, drv,
 162                                                             next_state);
 163         else
 164                 entered_state = cpuidle_enter_state(dev, drv, next_state);
 165
 166         trace_power_end_rcuidle(dev->cpu);
 167         trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
 168
 169         /* give the governor an opportunity to reflect on the outcome */
 170         if (cpuidle_curr_governor->reflect)
 171                 cpuidle_curr_governor->reflect(dev, entered_state);
 172
 173         return 0;
 174 }
 175
 176 /**
 177  * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
 178  */
 179 void cpuidle_install_idle_handler(void)
 180 {
 181         if (enabled_devices) {
 182                 /* Make sure all changes finished before we switch to new idle */
 183                 smp_wmb();
 184                 initialized = 1;
 185         }
 186 }
 187
 188 /**
 189  * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
 190  */
 191 void cpuidle_uninstall_idle_handler(void)
 192 {
 193         if (enabled_devices) {
 194                 initialized = 0;
 195                 kick_all_cpus_sync();
 196         }
 197 }
 198
 199 /**
 200  * cpuidle_pause_and_lock - temporarily disables CPUIDLE
 201  */
 202 void cpuidle_pause_and_lock(void)
 203 {
 204         mutex_lock(&cpuidle_lock);
 205         cpuidle_uninstall_idle_handler();
 206 }
 207
 208 EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
 209
 210 /**
 211  * cpuidle_resume_and_unlock - resumes CPUIDLE operation
 212  */
 213 void cpuidle_resume_and_unlock(void)
 214 {
 215         cpuidle_install_idle_handler();
 216         mutex_unlock(&cpuidle_lock);
 217 }
 218
 219 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
 220
 221 /* Currently used in suspend/resume path to suspend cpuidle */
 222 void cpuidle_pause(void)
 223 {
 224         mutex_lock(&cpuidle_lock);
 225         cpuidle_uninstall_idle_handler();
 226         mutex_unlock(&cpuidle_lock);
 227 }
 228
 229 /* Currently used in suspend/resume path to resume cpuidle */
 230 void cpuidle_resume(void)
 231 {
 232         mutex_lock(&cpuidle_lock);
 233         cpuidle_install_idle_handler();
 234         mutex_unlock(&cpuidle_lock);
 235 }
 236
 237 /**
 238  * cpuidle_wrap_enter - performs timekeeping and irqen around enter function
 239  * @dev: pointer to a valid cpuidle_device object
 240  * @drv: pointer to a valid cpuidle_driver object
 241  * @index: index of the target cpuidle state.
 242  */
 243 int cpuidle_wrap_enter(struct cpuidle_device *dev,
 244                                 struct cpuidle_driver *drv, int index,
 245                                 int (*enter)(struct cpuidle_device *dev,
 246                                         struct cpuidle_driver *drv, int index))
 247 {
 248         ktime_t time_start, time_end;
 249         s64 diff;
 250
 251         time_start = ktime_get();
 252
 253         index = enter(dev, drv, index);
 254
 255         time_end = ktime_get();
 256
 257         local_irq_enable();
 258
 259         diff = ktime_to_us(ktime_sub(time_end, time_start));
 260         if (diff > INT_MAX)
 261                 diff = INT_MAX;
 262
 263         dev->last_residency = (int) diff;
 264
 265         return index;
 266 }
 267
 268 #ifdef CONFIG_ARCH_HAS_CPU_RELAX
 269 static int poll_idle(struct cpuidle_device *dev,
 270                 struct cpuidle_driver *drv, int index)
 271 {
 272         ktime_t t1, t2;
 273         s64 diff;
 274
 275         t1 = ktime_get();
 276         local_irq_enable();
 277         while (!need_resched())
 278                 cpu_relax();
 279
 280         t2 = ktime_get();
 281         diff = ktime_to_us(ktime_sub(t2, t1));
 282         if (diff > INT_MAX)
 283                 diff = INT_MAX;
 284
 285         dev->last_residency = (int) diff;
 286
 287         return index;
 288 }
 289
 290 static void poll_idle_init(struct cpuidle_driver *drv)
 291 {
 292         struct cpuidle_state *state = &drv->states[0];
 293
 294         snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
 295         snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
 296         state->exit_latency = 0;
 297         state->target_residency = 0;
 298         state->power_usage = -1;
 299         state->flags = 0;
 300         state->enter = poll_idle;
 301         state->disabled = false;
 302 }
 303 #else
 304 static void poll_idle_init(struct cpuidle_driver *drv) {}
 305 #endif /* CONFIG_ARCH_HAS_CPU_RELAX */
 306
 307 /**
 308  * cpuidle_enable_device - enables idle PM for a CPU
 309  * @dev: the CPU
 310  *
 311  * This function must be called between cpuidle_pause_and_lock and
 312  * cpuidle_resume_and_unlock when used externally.
 313  */
 314 int cpuidle_enable_device(struct cpuidle_device *dev)
 315 {
 316         int ret, i;
 317         struct cpuidle_driver *drv;
 318
 319         if (!dev)
 320                 return -EINVAL;
 321
 322         if (dev->enabled)
 323                 return 0;
 324
 325         drv = cpuidle_get_cpu_driver(dev);
 326
 327         if (!drv || !cpuidle_curr_governor)
 328                 return -EIO;
 329
 330         if (!dev->state_count)
 331                 dev->state_count = drv->state_count;
 332
 333         if (dev->registered == 0) {
 334                 ret = __cpuidle_register_device(dev);
 335                 if (ret)
 336                         return ret;
 337         }
 338
 339         cpuidle_enter_ops = drv->en_core_tk_irqen ?
 340                 cpuidle_enter_tk : cpuidle_enter;
 341
 342         poll_idle_init(drv);
 343
 344         ret = cpuidle_add_device_sysfs(dev);
 345         if (ret)
 346                 return ret;
 347
 348         if (cpuidle_curr_governor->enable &&
 349             (ret = cpuidle_curr_governor->enable(drv, dev)))
 350                 goto fail_sysfs;
 351
 352         for (i = 0; i < dev->state_count; i++) {
 353                 dev->states_usage[i].usage = 0;
 354                 dev->states_usage[i].time = 0;
 355         }
 356         dev->last_residency = 0;
 357
 358         smp_wmb();
 359
 360         dev->enabled = 1;
 361
 362         enabled_devices++;
 363         return 0;
 364
 365 fail_sysfs:
 366         cpuidle_remove_device_sysfs(dev);
 367
 368         return ret;
 369 }
 370
 371 EXPORT_SYMBOL_GPL(cpuidle_enable_device);
 372
 373 /**
 374  * cpuidle_disable_device - disables idle PM for a CPU
 375  * @dev: the CPU
 376  *
 377  * This function must be called between cpuidle_pause_and_lock and
 378  * cpuidle_resume_and_unlock when used externally.
 379  */
 380 void cpuidle_disable_device(struct cpuidle_device *dev)
 381 {
 382         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 383
 384         if (!dev || !dev->enabled)
 385                 return;
 386
 387         if (!drv || !cpuidle_curr_governor)
 388                 return;
 389
 390         dev->enabled = 0;
 391
 392         if (cpuidle_curr_governor->disable)
 393                 cpuidle_curr_governor->disable(drv, dev);
 394
 395         cpuidle_remove_device_sysfs(dev);
 396         enabled_devices--;
 397 }
 398
 399 EXPORT_SYMBOL_GPL(cpuidle_disable_device);
 400
 401 /**
 402  * __cpuidle_register_device - internal register function called before register
 403  * and enable routines
 404  * @dev: the cpu
 405  *
 406  * cpuidle_lock mutex must be held before this is called
 407  */
 408 static int __cpuidle_register_device(struct cpuidle_device *dev)
 409 {
 410         int ret;
 411         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 412
 413         if (!try_module_get(drv->owner))
 414                 return -EINVAL;
 415
 416         per_cpu(cpuidle_devices, dev->cpu) = dev;
 417         list_add(&dev->device_list, &cpuidle_detected_devices);
 418         ret = cpuidle_add_sysfs(dev);
 419         if (ret)
 420                 goto err_sysfs;
 421
 422         ret = cpuidle_coupled_register_device(dev);
 423         if (ret)
 424                 goto err_coupled;
 425
 426         dev->registered = 1;
 427         return 0;
 428
 429 err_coupled:
 430         cpuidle_remove_sysfs(dev);
 431 err_sysfs:
 432         list_del(&dev->device_list);
 433         per_cpu(cpuidle_devices, dev->cpu) = NULL;
 434         module_put(drv->owner);
 435         return ret;
 436 }
 437
 438 /**
 439  * cpuidle_register_device - registers a CPU's idle PM feature
 440  * @dev: the cpu
 441  */
 442 int cpuidle_register_device(struct cpuidle_device *dev)
 443 {
 444         int ret;
 445
 446         if (!dev)
 447                 return -EINVAL;
 448
 449         mutex_lock(&cpuidle_lock);
 450
 451         if ((ret = __cpuidle_register_device(dev))) {
 452                 mutex_unlock(&cpuidle_lock);
 453                 return ret;
 454         }
 455
 456         cpuidle_enable_device(dev);
 457         cpuidle_install_idle_handler();
 458
 459         mutex_unlock(&cpuidle_lock);
 460
 461         return 0;
 462
 463 }
 464
 465 EXPORT_SYMBOL_GPL(cpuidle_register_device);
 466
 467 /**
 468  * cpuidle_unregister_device - unregisters a CPU's idle PM feature
 469  * @dev: the cpu
 470  */
 471 void cpuidle_unregister_device(struct cpuidle_device *dev)
 472 {
 473         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 474
 475         if (dev->registered == 0)
 476                 return;
 477
 478         cpuidle_pause_and_lock();
 479
 480         cpuidle_disable_device(dev);
 481
 482         cpuidle_remove_sysfs(dev);
 483         list_del(&dev->device_list);
 484         per_cpu(cpuidle_devices, dev->cpu) = NULL;
 485
 486         cpuidle_coupled_unregister_device(dev);
 487
 488         cpuidle_resume_and_unlock();
 489
 490         module_put(drv->owner);
 491 }
 492
 493 EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
 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);