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;
  73
  74         if (!drv)
  75                 return -ENODEV;
  76
  77         /* Find lowest-power state that supports long-term idle */
  78         for (i = drv->state_count - 1; i >= CPUIDLE_DRIVER_STATE_START; i--)
  79                 if (drv->states[i].enter_dead)
  80                         return drv->states[i].enter_dead(dev, i);
  81
  82         return -ENODEV;
  83 }
  84
  85 /**
  86  * cpuidle_enter_state - enter the state and update stats
  87  * @dev: cpuidle device for this cpu
  88  * @drv: cpuidle driver for this cpu
  89  * @next_state: index into drv->states of the state to enter
  90  */
  91 int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
  92                 int next_state)
  93 {
  94         int entered_state;
  95
  96         entered_state = cpuidle_enter_ops(dev, drv, next_state);
  97
  98         if (entered_state >= 0) {
  99                 /* Update cpuidle counters */
 100                 /* This can be moved to within driver enter routine
 101                  * but that results in multiple copies of same code.
 102                  */
 103                 dev->states_usage[entered_state].time += dev->last_residency;
 104                 dev->states_usage[entered_state].usage++;
 105         } else {
 106                 dev->last_residency = 0;
 107         }
 108
 109         return entered_state;
 110 }
 111
 112 /**
 113  * cpuidle_idle_call - the main idle loop
 114  *
 115  * NOTE: no locks or semaphores should be used here
 116  * return non-zero on failure
 117  */
 118 int cpuidle_idle_call(void)
 119 {
 120         struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
 121         struct cpuidle_driver *drv;
 122         int next_state, entered_state;
 123
 124         if (off)
 125                 return -ENODEV;
 126
 127         if (!initialized)
 128                 return -ENODEV;
 129
 130         /* check if the device is ready */
 131         if (!dev || !dev->enabled)
 132                 return -EBUSY;
 133
 134         drv = cpuidle_get_cpu_driver(dev);
 135
 136         /* ask the governor for the next state */
 137         next_state = cpuidle_curr_governor->select(drv, dev);
 138         if (need_resched()) {
 139                 dev->last_residency = 0;
 140                 /* give the governor an opportunity to reflect on the outcome */
 141                 if (cpuidle_curr_governor->reflect)
 142                         cpuidle_curr_governor->reflect(dev, next_state);
 143                 local_irq_enable();
 144                 return 0;
 145         }
 146
 147         trace_cpu_idle_rcuidle(next_state, dev->cpu);
 148
 149         if (cpuidle_state_is_coupled(dev, drv, next_state))
 150                 entered_state = cpuidle_enter_state_coupled(dev, drv,
 151                                                             next_state);
 152         else
 153                 entered_state = cpuidle_enter_state(dev, drv, next_state);
 154
 155         trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
 156
 157         /* give the governor an opportunity to reflect on the outcome */
 158         if (cpuidle_curr_governor->reflect)
 159                 cpuidle_curr_governor->reflect(dev, entered_state);
 160
 161         return 0;
 162 }
 163
 164 /**
 165  * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
 166  */
 167 void cpuidle_install_idle_handler(void)
 168 {
 169         if (enabled_devices) {
 170                 /* Make sure all changes finished before we switch to new idle */
 171                 smp_wmb();
 172                 initialized = 1;
 173         }
 174 }
 175
 176 /**
 177  * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
 178  */
 179 void cpuidle_uninstall_idle_handler(void)
 180 {
 181         if (enabled_devices) {
 182                 initialized = 0;
 183                 kick_all_cpus_sync();
 184         }
 185 }
 186
 187 /**
 188  * cpuidle_pause_and_lock - temporarily disables CPUIDLE
 189  */
 190 void cpuidle_pause_and_lock(void)
 191 {
 192         mutex_lock(&cpuidle_lock);
 193         cpuidle_uninstall_idle_handler();
 194 }
 195
 196 EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
 197
 198 /**
 199  * cpuidle_resume_and_unlock - resumes CPUIDLE operation
 200  */
 201 void cpuidle_resume_and_unlock(void)
 202 {
 203         cpuidle_install_idle_handler();
 204         mutex_unlock(&cpuidle_lock);
 205 }
 206
 207 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
 208
 209 /* Currently used in suspend/resume path to suspend cpuidle */
 210 void cpuidle_pause(void)
 211 {
 212         mutex_lock(&cpuidle_lock);
 213         cpuidle_uninstall_idle_handler();
 214         mutex_unlock(&cpuidle_lock);
 215 }
 216
 217 /* Currently used in suspend/resume path to resume cpuidle */
 218 void cpuidle_resume(void)
 219 {
 220         mutex_lock(&cpuidle_lock);
 221         cpuidle_install_idle_handler();
 222         mutex_unlock(&cpuidle_lock);
 223 }
 224
 225 /**
 226  * cpuidle_wrap_enter - performs timekeeping and irqen around enter function
 227  * @dev: pointer to a valid cpuidle_device object
 228  * @drv: pointer to a valid cpuidle_driver object
 229  * @index: index of the target cpuidle state.
 230  */
 231 int cpuidle_wrap_enter(struct cpuidle_device *dev,
 232                                 struct cpuidle_driver *drv, int index,
 233                                 int (*enter)(struct cpuidle_device *dev,
 234                                         struct cpuidle_driver *drv, int index))
 235 {
 236         ktime_t time_start, time_end;
 237         s64 diff;
 238
 239         time_start = ktime_get();
 240
 241         index = enter(dev, drv, index);
 242
 243         time_end = ktime_get();
 244
 245         local_irq_enable();
 246
 247         diff = ktime_to_us(ktime_sub(time_end, time_start));
 248         if (diff > INT_MAX)
 249                 diff = INT_MAX;
 250
 251         dev->last_residency = (int) diff;
 252
 253         return index;
 254 }
 255
 256 #ifdef CONFIG_ARCH_HAS_CPU_RELAX
 257 static int poll_idle(struct cpuidle_device *dev,
 258                 struct cpuidle_driver *drv, int index)
 259 {
 260         ktime_t t1, t2;
 261         s64 diff;
 262
 263         t1 = ktime_get();
 264         local_irq_enable();
 265         while (!need_resched())
 266                 cpu_relax();
 267
 268         t2 = ktime_get();
 269         diff = ktime_to_us(ktime_sub(t2, t1));
 270         if (diff > INT_MAX)
 271                 diff = INT_MAX;
 272
 273         dev->last_residency = (int) diff;
 274
 275         return index;
 276 }
 277
 278 static void poll_idle_init(struct cpuidle_driver *drv)
 279 {
 280         struct cpuidle_state *state = &drv->states[0];
 281
 282         snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
 283         snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
 284         state->exit_latency = 0;
 285         state->target_residency = 0;
 286         state->power_usage = -1;
 287         state->flags = 0;
 288         state->enter = poll_idle;
 289         state->disabled = false;
 290 }
 291 #else
 292 static void poll_idle_init(struct cpuidle_driver *drv) {}
 293 #endif /* CONFIG_ARCH_HAS_CPU_RELAX */
 294
 295 /**
 296  * cpuidle_enable_device - enables idle PM for a CPU
 297  * @dev: the CPU
 298  *
 299  * This function must be called between cpuidle_pause_and_lock and
 300  * cpuidle_resume_and_unlock when used externally.
 301  */
 302 int cpuidle_enable_device(struct cpuidle_device *dev)
 303 {
 304         int ret, i;
 305         struct cpuidle_driver *drv;
 306
 307         if (!dev)
 308                 return -EINVAL;
 309
 310         if (dev->enabled)
 311                 return 0;
 312
 313         drv = cpuidle_get_cpu_driver(dev);
 314
 315         if (!drv || !cpuidle_curr_governor)
 316                 return -EIO;
 317
 318         if (!dev->state_count)
 319                 dev->state_count = drv->state_count;
 320
 321         if (dev->registered == 0) {
 322                 ret = __cpuidle_register_device(dev);
 323                 if (ret)
 324                         return ret;
 325         }
 326
 327         cpuidle_enter_ops = drv->en_core_tk_irqen ?
 328                 cpuidle_enter_tk : cpuidle_enter;
 329
 330         poll_idle_init(drv);
 331
 332         ret = cpuidle_add_device_sysfs(dev);
 333         if (ret)
 334                 return ret;
 335
 336         if (cpuidle_curr_governor->enable &&
 337             (ret = cpuidle_curr_governor->enable(drv, dev)))
 338                 goto fail_sysfs;
 339
 340         for (i = 0; i < dev->state_count; i++) {
 341                 dev->states_usage[i].usage = 0;
 342                 dev->states_usage[i].time = 0;
 343         }
 344         dev->last_residency = 0;
 345
 346         smp_wmb();
 347
 348         dev->enabled = 1;
 349
 350         enabled_devices++;
 351         return 0;
 352
 353 fail_sysfs:
 354         cpuidle_remove_device_sysfs(dev);
 355
 356         return ret;
 357 }
 358
 359 EXPORT_SYMBOL_GPL(cpuidle_enable_device);
 360
 361 /**
 362  * cpuidle_disable_device - disables idle PM for a CPU
 363  * @dev: the CPU
 364  *
 365  * This function must be called between cpuidle_pause_and_lock and
 366  * cpuidle_resume_and_unlock when used externally.
 367  */
 368 void cpuidle_disable_device(struct cpuidle_device *dev)
 369 {
 370         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 371
 372         if (!dev || !dev->enabled)
 373                 return;
 374
 375         if (!drv || !cpuidle_curr_governor)
 376                 return;
 377
 378         dev->enabled = 0;
 379
 380         if (cpuidle_curr_governor->disable)
 381                 cpuidle_curr_governor->disable(drv, dev);
 382
 383         cpuidle_remove_device_sysfs(dev);
 384         enabled_devices--;
 385 }
 386
 387 EXPORT_SYMBOL_GPL(cpuidle_disable_device);
 388
 389 /**
 390  * __cpuidle_register_device - internal register function called before register
 391  * and enable routines
 392  * @dev: the cpu
 393  *
 394  * cpuidle_lock mutex must be held before this is called
 395  */
 396 static int __cpuidle_register_device(struct cpuidle_device *dev)
 397 {
 398         int ret;
 399         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 400
 401         if (!try_module_get(drv->owner))
 402                 return -EINVAL;
 403
 404         per_cpu(cpuidle_devices, dev->cpu) = dev;
 405         list_add(&dev->device_list, &cpuidle_detected_devices);
 406         ret = cpuidle_add_sysfs(dev);
 407         if (ret)
 408                 goto err_sysfs;
 409
 410         ret = cpuidle_coupled_register_device(dev);
 411         if (ret)
 412                 goto err_coupled;
 413
 414         dev->registered = 1;
 415         return 0;
 416
 417 err_coupled:
 418         cpuidle_remove_sysfs(dev);
 419 err_sysfs:
 420         list_del(&dev->device_list);
 421         per_cpu(cpuidle_devices, dev->cpu) = NULL;
 422         module_put(drv->owner);
 423         return ret;
 424 }
 425
 426 /**
 427  * cpuidle_register_device - registers a CPU's idle PM feature
 428  * @dev: the cpu
 429  */
 430 int cpuidle_register_device(struct cpuidle_device *dev)
 431 {
 432         int ret;
 433
 434         if (!dev)
 435                 return -EINVAL;
 436
 437         mutex_lock(&cpuidle_lock);
 438
 439         if ((ret = __cpuidle_register_device(dev))) {
 440                 mutex_unlock(&cpuidle_lock);
 441                 return ret;
 442         }
 443
 444         cpuidle_enable_device(dev);
 445         cpuidle_install_idle_handler();
 446
 447         mutex_unlock(&cpuidle_lock);
 448
 449         return 0;
 450
 451 }
 452
 453 EXPORT_SYMBOL_GPL(cpuidle_register_device);
 454
 455 /**
 456  * cpuidle_unregister_device - unregisters a CPU's idle PM feature
 457  * @dev: the cpu
 458  */
 459 void cpuidle_unregister_device(struct cpuidle_device *dev)
 460 {
 461         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 462
 463         if (dev->registered == 0)
 464                 return;
 465
 466         cpuidle_pause_and_lock();
 467
 468         cpuidle_disable_device(dev);
 469
 470         cpuidle_remove_sysfs(dev);
 471         list_del(&dev->device_list);
 472         per_cpu(cpuidle_devices, dev->cpu) = NULL;
 473
 474         cpuidle_coupled_unregister_device(dev);
 475
 476         cpuidle_resume_and_unlock();
 477
 478         module_put(drv->owner);
 479 }
 480
 481 EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
 482
 483 #ifdef CONFIG_SMP
 484
 485 static void smp_callback(void *v)
 486 {
 487         /* we already woke the CPU up, nothing more to do */
 488 }
 489
 490 /*
 491  * This function gets called when a part of the kernel has a new latency
 492  * requirement.  This means we need to get all processors out of their C-state,
 493  * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
 494  * wakes them all right up.
 495  */
 496 static int cpuidle_latency_notify(struct notifier_block *b,
 497                 unsigned long l, void *v)
 498 {
 499         smp_call_function(smp_callback, NULL, 1);
 500         return NOTIFY_OK;
 501 }
 502
 503 static struct notifier_block cpuidle_latency_notifier = {
 504         .notifier_call = cpuidle_latency_notify,
 505 };
 506
 507 static inline void latency_notifier_init(struct notifier_block *n)
 508 {
 509         pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
 510 }
 511
 512 #else /* CONFIG_SMP */
 513
 514 #define latency_notifier_init(x) do { } while (0)
 515
 516 #endif /* CONFIG_SMP */
 517
 518 /**
 519  * cpuidle_init - core initializer
 520  */
 521 static int __init cpuidle_init(void)
 522 {
 523         int ret;
 524
 525         if (cpuidle_disabled())
 526                 return -ENODEV;
 527
 528         ret = cpuidle_add_interface(cpu_subsys.dev_root);
 529         if (ret)
 530                 return ret;
 531
 532         latency_notifier_init(&cpuidle_latency_notifier);
 533
 534         return 0;
 535 }
 536
 537 module_param(off, int, 0444);
 538 core_initcall(cpuidle_init);