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_idle_call - the main idle loop
  96  *
  97  * NOTE: no locks or semaphores should be used here
  98  * return non-zero on failure
  99  */
 100 int cpuidle_idle_call(void)
 101 {
 102         struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
 103         struct cpuidle_driver *drv = cpuidle_get_driver();
 104         int next_state, entered_state;
 105
 106         if (off)
 107                 return -ENODEV;
 108
 109         if (!initialized)
 110                 return -ENODEV;
 111
 112         /* check if the device is ready */
 113         if (!dev || !dev->enabled)
 114                 return -EBUSY;
 115
 116 #if 0
 117         /* shows regressions, re-enable for 2.6.29 */
 118         /*
 119          * run any timers that can be run now, at this point
 120          * before calculating the idle duration etc.
 121          */
 122         hrtimer_peek_ahead_timers();
 123 #endif
 124
 125         /* ask the governor for the next state */
 126         next_state = cpuidle_curr_governor->select(drv, dev);
 127         if (need_resched()) {
 128                 local_irq_enable();
 129                 return 0;
 130         }
 131
 132         trace_power_start_rcuidle(POWER_CSTATE, next_state, dev->cpu);
 133         trace_cpu_idle_rcuidle(next_state, dev->cpu);
 134
 135         entered_state = cpuidle_enter_ops(dev, drv, next_state);
 136
 137         trace_power_end_rcuidle(dev->cpu);
 138         trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
 139
 140         if (entered_state >= 0) {
 141                 /* Update cpuidle counters */
 142                 /* This can be moved to within driver enter routine
 143                  * but that results in multiple copies of same code.
 144                  */
 145                 dev->states_usage[entered_state].time +=
 146                                 (unsigned long long)dev->last_residency;
 147                 dev->states_usage[entered_state].usage++;
 148         } else {
 149                 dev->last_residency = 0;
 150         }
 151
 152         /* give the governor an opportunity to reflect on the outcome */
 153         if (cpuidle_curr_governor->reflect)
 154                 cpuidle_curr_governor->reflect(dev, entered_state);
 155
 156         return 0;
 157 }
 158
 159 /**
 160  * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
 161  */
 162 void cpuidle_install_idle_handler(void)
 163 {
 164         if (enabled_devices) {
 165                 /* Make sure all changes finished before we switch to new idle */
 166                 smp_wmb();
 167                 initialized = 1;
 168         }
 169 }
 170
 171 /**
 172  * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
 173  */
 174 void cpuidle_uninstall_idle_handler(void)
 175 {
 176         if (enabled_devices) {
 177                 initialized = 0;
 178                 kick_all_cpus_sync();
 179         }
 180 }
 181
 182 /**
 183  * cpuidle_pause_and_lock - temporarily disables CPUIDLE
 184  */
 185 void cpuidle_pause_and_lock(void)
 186 {
 187         mutex_lock(&cpuidle_lock);
 188         cpuidle_uninstall_idle_handler();
 189 }
 190
 191 EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
 192
 193 /**
 194  * cpuidle_resume_and_unlock - resumes CPUIDLE operation
 195  */
 196 void cpuidle_resume_and_unlock(void)
 197 {
 198         cpuidle_install_idle_handler();
 199         mutex_unlock(&cpuidle_lock);
 200 }
 201
 202 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
 203
 204 /**
 205  * cpuidle_wrap_enter - performs timekeeping and irqen around enter function
 206  * @dev: pointer to a valid cpuidle_device object
 207  * @drv: pointer to a valid cpuidle_driver object
 208  * @index: index of the target cpuidle state.
 209  */
 210 int cpuidle_wrap_enter(struct cpuidle_device *dev,
 211                                 struct cpuidle_driver *drv, int index,
 212                                 int (*enter)(struct cpuidle_device *dev,
 213                                         struct cpuidle_driver *drv, int index))
 214 {
 215         ktime_t time_start, time_end;
 216         s64 diff;
 217
 218         time_start = ktime_get();
 219
 220         index = enter(dev, drv, index);
 221
 222         time_end = ktime_get();
 223
 224         local_irq_enable();
 225
 226         diff = ktime_to_us(ktime_sub(time_end, time_start));
 227         if (diff > INT_MAX)
 228                 diff = INT_MAX;
 229
 230         dev->last_residency = (int) diff;
 231
 232         return index;
 233 }
 234
 235 #ifdef CONFIG_ARCH_HAS_CPU_RELAX
 236 static int poll_idle(struct cpuidle_device *dev,
 237                 struct cpuidle_driver *drv, int index)
 238 {
 239         ktime_t t1, t2;
 240         s64 diff;
 241
 242         t1 = ktime_get();
 243         local_irq_enable();
 244         while (!need_resched())
 245                 cpu_relax();
 246
 247         t2 = ktime_get();
 248         diff = ktime_to_us(ktime_sub(t2, t1));
 249         if (diff > INT_MAX)
 250                 diff = INT_MAX;
 251
 252         dev->last_residency = (int) diff;
 253
 254         return index;
 255 }
 256
 257 static void poll_idle_init(struct cpuidle_driver *drv)
 258 {
 259         struct cpuidle_state *state = &drv->states[0];
 260
 261         snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
 262         snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
 263         state->exit_latency = 0;
 264         state->target_residency = 0;
 265         state->power_usage = -1;
 266         state->flags = 0;
 267         state->enter = poll_idle;
 268         state->disable = 0;
 269 }
 270 #else
 271 static void poll_idle_init(struct cpuidle_driver *drv) {}
 272 #endif /* CONFIG_ARCH_HAS_CPU_RELAX */
 273
 274 /**
 275  * cpuidle_enable_device - enables idle PM for a CPU
 276  * @dev: the CPU
 277  *
 278  * This function must be called between cpuidle_pause_and_lock and
 279  * cpuidle_resume_and_unlock when used externally.
 280  */
 281 int cpuidle_enable_device(struct cpuidle_device *dev)
 282 {
 283         int ret, i;
 284         struct cpuidle_driver *drv = cpuidle_get_driver();
 285
 286         if (dev->enabled)
 287                 return 0;
 288         if (!drv || !cpuidle_curr_governor)
 289                 return -EIO;
 290         if (!dev->state_count)
 291                 dev->state_count = drv->state_count;
 292
 293         if (dev->registered == 0) {
 294                 ret = __cpuidle_register_device(dev);
 295                 if (ret)
 296                         return ret;
 297         }
 298
 299         cpuidle_enter_ops = drv->en_core_tk_irqen ?
 300                 cpuidle_enter_tk : cpuidle_enter;
 301
 302         poll_idle_init(drv);
 303
 304         if ((ret = cpuidle_add_state_sysfs(dev)))
 305                 return ret;
 306
 307         if (cpuidle_curr_governor->enable &&
 308             (ret = cpuidle_curr_governor->enable(drv, dev)))
 309                 goto fail_sysfs;
 310
 311         for (i = 0; i < dev->state_count; i++) {
 312                 dev->states_usage[i].usage = 0;
 313                 dev->states_usage[i].time = 0;
 314         }
 315         dev->last_residency = 0;
 316
 317         smp_wmb();
 318
 319         dev->enabled = 1;
 320
 321         enabled_devices++;
 322         return 0;
 323
 324 fail_sysfs:
 325         cpuidle_remove_state_sysfs(dev);
 326
 327         return ret;
 328 }
 329
 330 EXPORT_SYMBOL_GPL(cpuidle_enable_device);
 331
 332 /**
 333  * cpuidle_disable_device - disables idle PM for a CPU
 334  * @dev: the CPU
 335  *
 336  * This function must be called between cpuidle_pause_and_lock and
 337  * cpuidle_resume_and_unlock when used externally.
 338  */
 339 void cpuidle_disable_device(struct cpuidle_device *dev)
 340 {
 341         if (!dev->enabled)
 342                 return;
 343         if (!cpuidle_get_driver() || !cpuidle_curr_governor)
 344                 return;
 345
 346         dev->enabled = 0;
 347
 348         if (cpuidle_curr_governor->disable)
 349                 cpuidle_curr_governor->disable(cpuidle_get_driver(), dev);
 350
 351         cpuidle_remove_state_sysfs(dev);
 352         enabled_devices--;
 353 }
 354
 355 EXPORT_SYMBOL_GPL(cpuidle_disable_device);
 356
 357 /**
 358  * __cpuidle_register_device - internal register function called before register
 359  * and enable routines
 360  * @dev: the cpu
 361  *
 362  * cpuidle_lock mutex must be held before this is called
 363  */
 364 static int __cpuidle_register_device(struct cpuidle_device *dev)
 365 {
 366         int ret;
 367         struct device *cpu_dev = get_cpu_device((unsigned long)dev->cpu);
 368         struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();
 369
 370         if (!dev)
 371                 return -EINVAL;
 372         if (!try_module_get(cpuidle_driver->owner))
 373                 return -EINVAL;
 374
 375         init_completion(&dev->kobj_unregister);
 376
 377         per_cpu(cpuidle_devices, dev->cpu) = dev;
 378         list_add(&dev->device_list, &cpuidle_detected_devices);
 379         if ((ret = cpuidle_add_sysfs(cpu_dev))) {
 380                 module_put(cpuidle_driver->owner);
 381                 return ret;
 382         }
 383
 384         dev->registered = 1;
 385         return 0;
 386 }
 387
 388 /**
 389  * cpuidle_register_device - registers a CPU's idle PM feature
 390  * @dev: the cpu
 391  */
 392 int cpuidle_register_device(struct cpuidle_device *dev)
 393 {
 394         int ret;
 395
 396         mutex_lock(&cpuidle_lock);
 397
 398         if ((ret = __cpuidle_register_device(dev))) {
 399                 mutex_unlock(&cpuidle_lock);
 400                 return ret;
 401         }
 402
 403         cpuidle_enable_device(dev);
 404         cpuidle_install_idle_handler();
 405
 406         mutex_unlock(&cpuidle_lock);
 407
 408         return 0;
 409
 410 }
 411
 412 EXPORT_SYMBOL_GPL(cpuidle_register_device);
 413
 414 /**
 415  * cpuidle_unregister_device - unregisters a CPU's idle PM feature
 416  * @dev: the cpu
 417  */
 418 void cpuidle_unregister_device(struct cpuidle_device *dev)
 419 {
 420         struct device *cpu_dev = get_cpu_device((unsigned long)dev->cpu);
 421         struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();
 422
 423         if (dev->registered == 0)
 424                 return;
 425
 426         cpuidle_pause_and_lock();
 427
 428         cpuidle_disable_device(dev);
 429
 430         cpuidle_remove_sysfs(cpu_dev);
 431         list_del(&dev->device_list);
 432         wait_for_completion(&dev->kobj_unregister);
 433         per_cpu(cpuidle_devices, dev->cpu) = NULL;
 434
 435         cpuidle_resume_and_unlock();
 436
 437         module_put(cpuidle_driver->owner);
 438 }
 439
 440 EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
 441
 442 #ifdef CONFIG_SMP
 443
 444 static void smp_callback(void *v)
 445 {
 446         /* we already woke the CPU up, nothing more to do */
 447 }
 448
 449 /*
 450  * This function gets called when a part of the kernel has a new latency
 451  * requirement.  This means we need to get all processors out of their C-state,
 452  * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
 453  * wakes them all right up.
 454  */
 455 static int cpuidle_latency_notify(struct notifier_block *b,
 456                 unsigned long l, void *v)
 457 {
 458         smp_call_function(smp_callback, NULL, 1);
 459         return NOTIFY_OK;
 460 }
 461
 462 static struct notifier_block cpuidle_latency_notifier = {
 463         .notifier_call = cpuidle_latency_notify,
 464 };
 465
 466 static inline void latency_notifier_init(struct notifier_block *n)
 467 {
 468         pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
 469 }
 470
 471 #else /* CONFIG_SMP */
 472
 473 #define latency_notifier_init(x) do { } while (0)
 474
 475 #endif /* CONFIG_SMP */
 476
 477 /**
 478  * cpuidle_init - core initializer
 479  */
 480 static int __init cpuidle_init(void)
 481 {
 482         int ret;
 483
 484         if (cpuidle_disabled())
 485                 return -ENODEV;
 486
 487         ret = cpuidle_add_interface(cpu_subsys.dev_root);
 488         if (ret)
 489                 return ret;
 490
 491         latency_notifier_init(&cpuidle_latency_notifier);
 492
 493         return 0;
 494 }
 495
 496 module_param(off, int, 0444);
 497 core_initcall(cpuidle_init);