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_driver();
  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 = cpuidle_get_driver();
 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         /* ask the governor for the next state */
 145         next_state = cpuidle_curr_governor->select(drv, dev);
 146         if (need_resched()) {
 147                 local_irq_enable();
 148                 return 0;
 149         }
 150
 151         trace_power_start_rcuidle(POWER_CSTATE, next_state, dev->cpu);
 152         trace_cpu_idle_rcuidle(next_state, dev->cpu);
 153
 154         if (cpuidle_state_is_coupled(dev, drv, next_state))
 155                 entered_state = cpuidle_enter_state_coupled(dev, drv,
 156                                                             next_state);
 157         else
 158                 entered_state = cpuidle_enter_state(dev, drv, next_state);
 159
 160         trace_power_end_rcuidle(dev->cpu);
 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 /**
 232  * cpuidle_wrap_enter - performs timekeeping and irqen around enter function
 233  * @dev: pointer to a valid cpuidle_device object
 234  * @drv: pointer to a valid cpuidle_driver object
 235  * @index: index of the target cpuidle state.
 236  */
 237 int cpuidle_wrap_enter(struct cpuidle_device *dev,
 238                                 struct cpuidle_driver *drv, int index,
 239                                 int (*enter)(struct cpuidle_device *dev,
 240                                         struct cpuidle_driver *drv, int index))
 241 {
 242         ktime_t time_start, time_end;
 243         s64 diff;
 244
 245         time_start = ktime_get();
 246
 247         index = enter(dev, drv, index);
 248
 249         time_end = ktime_get();
 250
 251         local_irq_enable();
 252
 253         diff = ktime_to_us(ktime_sub(time_end, time_start));
 254         if (diff > INT_MAX)
 255                 diff = INT_MAX;
 256
 257         dev->last_residency = (int) diff;
 258
 259         return index;
 260 }
 261
 262 #ifdef CONFIG_ARCH_HAS_CPU_RELAX
 263 static int poll_idle(struct cpuidle_device *dev,
 264                 struct cpuidle_driver *drv, int index)
 265 {
 266         ktime_t t1, t2;
 267         s64 diff;
 268
 269         t1 = ktime_get();
 270         local_irq_enable();
 271         while (!need_resched())
 272                 cpu_relax();
 273
 274         t2 = ktime_get();
 275         diff = ktime_to_us(ktime_sub(t2, t1));
 276         if (diff > INT_MAX)
 277                 diff = INT_MAX;
 278
 279         dev->last_residency = (int) diff;
 280
 281         return index;
 282 }
 283
 284 static void poll_idle_init(struct cpuidle_driver *drv)
 285 {
 286         struct cpuidle_state *state = &drv->states[0];
 287
 288         snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
 289         snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
 290         state->exit_latency = 0;
 291         state->target_residency = 0;
 292         state->power_usage = -1;
 293         state->flags = 0;
 294         state->enter = poll_idle;
 295         state->disabled = false;
 296 }
 297 #else
 298 static void poll_idle_init(struct cpuidle_driver *drv) {}
 299 #endif /* CONFIG_ARCH_HAS_CPU_RELAX */
 300
 301 /**
 302  * cpuidle_enable_device - enables idle PM for a CPU
 303  * @dev: the CPU
 304  *
 305  * This function must be called between cpuidle_pause_and_lock and
 306  * cpuidle_resume_and_unlock when used externally.
 307  */
 308 int cpuidle_enable_device(struct cpuidle_device *dev)
 309 {
 310         int ret, i;
 311         struct cpuidle_driver *drv = cpuidle_get_driver();
 312
 313         if (!dev)
 314                 return -EINVAL;
 315
 316         if (dev->enabled)
 317                 return 0;
 318         if (!drv || !cpuidle_curr_governor)
 319                 return -EIO;
 320         if (!dev->state_count)
 321                 dev->state_count = drv->state_count;
 322
 323         if (dev->registered == 0) {
 324                 ret = __cpuidle_register_device(dev);
 325                 if (ret)
 326                         return ret;
 327         }
 328
 329         cpuidle_enter_ops = drv->en_core_tk_irqen ?
 330                 cpuidle_enter_tk : cpuidle_enter;
 331
 332         poll_idle_init(drv);
 333
 334         if ((ret = cpuidle_add_state_sysfs(dev)))
 335                 return ret;
 336
 337         if (cpuidle_curr_governor->enable &&
 338             (ret = cpuidle_curr_governor->enable(drv, dev)))
 339                 goto fail_sysfs;
 340
 341         for (i = 0; i < dev->state_count; i++) {
 342                 dev->states_usage[i].usage = 0;
 343                 dev->states_usage[i].time = 0;
 344         }
 345         dev->last_residency = 0;
 346
 347         smp_wmb();
 348
 349         dev->enabled = 1;
 350
 351         enabled_devices++;
 352         return 0;
 353
 354 fail_sysfs:
 355         cpuidle_remove_state_sysfs(dev);
 356
 357         return ret;
 358 }
 359
 360 EXPORT_SYMBOL_GPL(cpuidle_enable_device);
 361
 362 /**
 363  * cpuidle_disable_device - disables idle PM for a CPU
 364  * @dev: the CPU
 365  *
 366  * This function must be called between cpuidle_pause_and_lock and
 367  * cpuidle_resume_and_unlock when used externally.
 368  */
 369 void cpuidle_disable_device(struct cpuidle_device *dev)
 370 {
 371         if (!dev || !dev->enabled)
 372                 return;
 373         if (!cpuidle_get_driver() || !cpuidle_curr_governor)
 374                 return;
 375
 376         dev->enabled = 0;
 377
 378         if (cpuidle_curr_governor->disable)
 379                 cpuidle_curr_governor->disable(cpuidle_get_driver(), dev);
 380
 381         cpuidle_remove_state_sysfs(dev);
 382         enabled_devices--;
 383 }
 384
 385 EXPORT_SYMBOL_GPL(cpuidle_disable_device);
 386
 387 /**
 388  * __cpuidle_register_device - internal register function called before register
 389  * and enable routines
 390  * @dev: the cpu
 391  *
 392  * cpuidle_lock mutex must be held before this is called
 393  */
 394 static int __cpuidle_register_device(struct cpuidle_device *dev)
 395 {
 396         int ret;
 397         struct device *cpu_dev = get_cpu_device((unsigned long)dev->cpu);
 398         struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();
 399
 400         if (!try_module_get(cpuidle_driver->owner))
 401                 return -EINVAL;
 402
 403         init_completion(&dev->kobj_unregister);
 404
 405         per_cpu(cpuidle_devices, dev->cpu) = dev;
 406         list_add(&dev->device_list, &cpuidle_detected_devices);
 407         ret = cpuidle_add_sysfs(cpu_dev);
 408         if (ret)
 409                 goto err_sysfs;
 410
 411         ret = cpuidle_coupled_register_device(dev);
 412         if (ret)
 413                 goto err_coupled;
 414
 415         dev->registered = 1;
 416         return 0;
 417
 418 err_coupled:
 419         cpuidle_remove_sysfs(cpu_dev);
 420         wait_for_completion(&dev->kobj_unregister);
 421 err_sysfs:
 422         list_del(&dev->device_list);
 423         per_cpu(cpuidle_devices, dev->cpu) = NULL;
 424         module_put(cpuidle_driver->owner);
 425         return ret;
 426 }
 427
 428 /**
 429  * cpuidle_register_device - registers a CPU's idle PM feature
 430  * @dev: the cpu
 431  */
 432 int cpuidle_register_device(struct cpuidle_device *dev)
 433 {
 434         int ret;
 435
 436         if (!dev)
 437                 return -EINVAL;
 438
 439         mutex_lock(&cpuidle_lock);
 440
 441         if ((ret = __cpuidle_register_device(dev))) {
 442                 mutex_unlock(&cpuidle_lock);
 443                 return ret;
 444         }
 445
 446         cpuidle_enable_device(dev);
 447         cpuidle_install_idle_handler();
 448
 449         mutex_unlock(&cpuidle_lock);
 450
 451         return 0;
 452
 453 }
 454
 455 EXPORT_SYMBOL_GPL(cpuidle_register_device);
 456
 457 /**
 458  * cpuidle_unregister_device - unregisters a CPU's idle PM feature
 459  * @dev: the cpu
 460  */
 461 void cpuidle_unregister_device(struct cpuidle_device *dev)
 462 {
 463         struct device *cpu_dev = get_cpu_device((unsigned long)dev->cpu);
 464         struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();
 465
 466         if (dev->registered == 0)
 467                 return;
 468
 469         cpuidle_pause_and_lock();
 470
 471         cpuidle_disable_device(dev);
 472
 473         cpuidle_remove_sysfs(cpu_dev);
 474         list_del(&dev->device_list);
 475         wait_for_completion(&dev->kobj_unregister);
 476         per_cpu(cpuidle_devices, dev->cpu) = NULL;
 477
 478         cpuidle_coupled_unregister_device(dev);
 479
 480         cpuidle_resume_and_unlock();
 481
 482         module_put(cpuidle_driver->owner);
 483 }
 484
 485 EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
 486
 487 #ifdef CONFIG_SMP
 488
 489 static void smp_callback(void *v)
 490 {
 491         /* we already woke the CPU up, nothing more to do */
 492 }
 493
 494 /*
 495  * This function gets called when a part of the kernel has a new latency
 496  * requirement.  This means we need to get all processors out of their C-state,
 497  * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
 498  * wakes them all right up.
 499  */
 500 static int cpuidle_latency_notify(struct notifier_block *b,
 501                 unsigned long l, void *v)
 502 {
 503         smp_call_function(smp_callback, NULL, 1);
 504         return NOTIFY_OK;
 505 }
 506
 507 static struct notifier_block cpuidle_latency_notifier = {
 508         .notifier_call = cpuidle_latency_notify,
 509 };
 510
 511 static inline void latency_notifier_init(struct notifier_block *n)
 512 {
 513         pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
 514 }
 515
 516 #else /* CONFIG_SMP */
 517
 518 #define latency_notifier_init(x) do { } while (0)
 519
 520 #endif /* CONFIG_SMP */
 521
 522 /**
 523  * cpuidle_init - core initializer
 524  */
 525 static int __init cpuidle_init(void)
 526 {
 527         int ret;
 528
 529         if (cpuidle_disabled())
 530                 return -ENODEV;
 531
 532         ret = cpuidle_add_interface(cpu_subsys.dev_root);
 533         if (ret)
 534                 return ret;
 535
 536         latency_notifier_init(&cpuidle_latency_notifier);
 537
 538         return 0;
 539 }
 540
 541 module_param(off, int, 0444);
 542 core_initcall(cpuidle_init);