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_enabled - check if the cpuidle framework is ready
  69  * @dev: cpuidle device for this cpu
  70  * @drv: cpuidle driver for this cpu
  71  *
  72  * Return 0 on success, otherwise:
  73  * -NODEV : the cpuidle framework is not available
  74  * -EBUSY : the cpuidle framework is not initialized
  75  */
  76 int cpuidle_enabled(struct cpuidle_driver *drv, struct cpuidle_device *dev)
  77 {
  78         if (off || !initialized)
  79                 return -ENODEV;
  80
  81         if (!drv || !dev || !dev->enabled)
  82                 return -EBUSY;
  83
  84         return 0;
  85 }
  86
  87 /**
  88  * cpuidle_enter_state - enter the state and update stats
  89  * @dev: cpuidle device for this cpu
  90  * @drv: cpuidle driver for this cpu
  91  * @next_state: index into drv->states of the state to enter
  92  */
  93 int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
  94                         int index)
  95 {
  96         int entered_state;
  97
  98         struct cpuidle_state *target_state = &drv->states[index];
  99         ktime_t time_start, time_end;
 100         s64 diff;
 101
 102         time_start = ktime_get();
 103
 104         entered_state = target_state->enter(dev, drv, index);
 105
 106         time_end = ktime_get();
 107
 108         if (!cpuidle_state_is_coupled(dev, drv, entered_state))
 109                 local_irq_enable();
 110
 111         diff = ktime_to_us(ktime_sub(time_end, time_start));
 112         if (diff > INT_MAX)
 113                 diff = INT_MAX;
 114
 115         dev->last_residency = (int) diff;
 116
 117         if (entered_state >= 0) {
 118                 /* Update cpuidle counters */
 119                 /* This can be moved to within driver enter routine
 120                  * but that results in multiple copies of same code.
 121                  */
 122                 dev->states_usage[entered_state].time += dev->last_residency;
 123                 dev->states_usage[entered_state].usage++;
 124         } else {
 125                 dev->last_residency = 0;
 126         }
 127
 128         return entered_state;
 129 }
 130
 131 /**
 132  * cpuidle_select - ask the cpuidle framework to choose an idle state
 133  *
 134  * @drv: the cpuidle driver
 135  * @dev: the cpuidle device
 136  *
 137  * Returns the index of the idle state.
 138  */
 139 int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
 140 {
 141         return cpuidle_curr_governor->select(drv, dev);
 142 }
 143
 144 /**
 145  * cpuidle_enter - enter into the specified idle state
 146  *
 147  * @drv:   the cpuidle driver tied with the cpu
 148  * @dev:   the cpuidle device
 149  * @index: the index in the idle state table
 150  *
 151  * Returns the index in the idle state, < 0 in case of error.
 152  * The error code depends on the backend driver
 153  */
 154 int cpuidle_enter(struct cpuidle_driver *drv, struct cpuidle_device *dev,
 155                   int index)
 156 {
 157         if (cpuidle_state_is_coupled(dev, drv, index))
 158                 return cpuidle_enter_state_coupled(dev, drv, index);
 159         return cpuidle_enter_state(dev, drv, index);
 160 }
 161
 162 /**
 163  * cpuidle_reflect - tell the underlying governor what was the state
 164  * we were in
 165  *
 166  * @dev  : the cpuidle device
 167  * @index: the index in the idle state table
 168  *
 169  */
 170 void cpuidle_reflect(struct cpuidle_device *dev, int index)
 171 {
 172         if (cpuidle_curr_governor->reflect)
 173                 cpuidle_curr_governor->reflect(dev, index);
 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_enable_device - enables idle PM for a CPU
 239  * @dev: the CPU
 240  *
 241  * This function must be called between cpuidle_pause_and_lock and
 242  * cpuidle_resume_and_unlock when used externally.
 243  */
 244 int cpuidle_enable_device(struct cpuidle_device *dev)
 245 {
 246         int ret;
 247         struct cpuidle_driver *drv;
 248
 249         if (!dev)
 250                 return -EINVAL;
 251
 252         if (dev->enabled)
 253                 return 0;
 254
 255         drv = cpuidle_get_cpu_driver(dev);
 256
 257         if (!drv || !cpuidle_curr_governor)
 258                 return -EIO;
 259
 260         if (!dev->registered)
 261                 return -EINVAL;
 262
 263         if (!dev->state_count)
 264                 dev->state_count = drv->state_count;
 265
 266         ret = cpuidle_add_device_sysfs(dev);
 267         if (ret)
 268                 return ret;
 269
 270         if (cpuidle_curr_governor->enable &&
 271             (ret = cpuidle_curr_governor->enable(drv, dev)))
 272                 goto fail_sysfs;
 273
 274         smp_wmb();
 275
 276         dev->enabled = 1;
 277
 278         enabled_devices++;
 279         return 0;
 280
 281 fail_sysfs:
 282         cpuidle_remove_device_sysfs(dev);
 283
 284         return ret;
 285 }
 286
 287 EXPORT_SYMBOL_GPL(cpuidle_enable_device);
 288
 289 /**
 290  * cpuidle_disable_device - disables idle PM for a CPU
 291  * @dev: the CPU
 292  *
 293  * This function must be called between cpuidle_pause_and_lock and
 294  * cpuidle_resume_and_unlock when used externally.
 295  */
 296 void cpuidle_disable_device(struct cpuidle_device *dev)
 297 {
 298         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 299
 300         if (!dev || !dev->enabled)
 301                 return;
 302
 303         if (!drv || !cpuidle_curr_governor)
 304                 return;
 305
 306         dev->enabled = 0;
 307
 308         if (cpuidle_curr_governor->disable)
 309                 cpuidle_curr_governor->disable(drv, dev);
 310
 311         cpuidle_remove_device_sysfs(dev);
 312         enabled_devices--;
 313 }
 314
 315 EXPORT_SYMBOL_GPL(cpuidle_disable_device);
 316
 317 static void __cpuidle_unregister_device(struct cpuidle_device *dev)
 318 {
 319         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 320
 321         list_del(&dev->device_list);
 322         per_cpu(cpuidle_devices, dev->cpu) = NULL;
 323         module_put(drv->owner);
 324 }
 325
 326 static void __cpuidle_device_init(struct cpuidle_device *dev)
 327 {
 328         memset(dev->states_usage, 0, sizeof(dev->states_usage));
 329         dev->last_residency = 0;
 330 }
 331
 332 /**
 333  * __cpuidle_register_device - internal register function called before register
 334  * and enable routines
 335  * @dev: the cpu
 336  *
 337  * cpuidle_lock mutex must be held before this is called
 338  */
 339 static int __cpuidle_register_device(struct cpuidle_device *dev)
 340 {
 341         int ret;
 342         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 343
 344         if (!try_module_get(drv->owner))
 345                 return -EINVAL;
 346
 347         per_cpu(cpuidle_devices, dev->cpu) = dev;
 348         list_add(&dev->device_list, &cpuidle_detected_devices);
 349
 350         ret = cpuidle_coupled_register_device(dev);
 351         if (ret)
 352                 __cpuidle_unregister_device(dev);
 353         else
 354                 dev->registered = 1;
 355
 356         return ret;
 357 }
 358
 359 /**
 360  * cpuidle_register_device - registers a CPU's idle PM feature
 361  * @dev: the cpu
 362  */
 363 int cpuidle_register_device(struct cpuidle_device *dev)
 364 {
 365         int ret = -EBUSY;
 366
 367         if (!dev)
 368                 return -EINVAL;
 369
 370         mutex_lock(&cpuidle_lock);
 371
 372         if (dev->registered)
 373                 goto out_unlock;
 374
 375         __cpuidle_device_init(dev);
 376
 377         ret = __cpuidle_register_device(dev);
 378         if (ret)
 379                 goto out_unlock;
 380
 381         ret = cpuidle_add_sysfs(dev);
 382         if (ret)
 383                 goto out_unregister;
 384
 385         ret = cpuidle_enable_device(dev);
 386         if (ret)
 387                 goto out_sysfs;
 388
 389         cpuidle_install_idle_handler();
 390
 391 out_unlock:
 392         mutex_unlock(&cpuidle_lock);
 393
 394         return ret;
 395
 396 out_sysfs:
 397         cpuidle_remove_sysfs(dev);
 398 out_unregister:
 399         __cpuidle_unregister_device(dev);
 400         goto out_unlock;
 401 }
 402
 403 EXPORT_SYMBOL_GPL(cpuidle_register_device);
 404
 405 /**
 406  * cpuidle_unregister_device - unregisters a CPU's idle PM feature
 407  * @dev: the cpu
 408  */
 409 void cpuidle_unregister_device(struct cpuidle_device *dev)
 410 {
 411         if (!dev || dev->registered == 0)
 412                 return;
 413
 414         cpuidle_pause_and_lock();
 415
 416         cpuidle_disable_device(dev);
 417
 418         cpuidle_remove_sysfs(dev);
 419
 420         __cpuidle_unregister_device(dev);
 421
 422         cpuidle_coupled_unregister_device(dev);
 423
 424         cpuidle_resume_and_unlock();
 425 }
 426
 427 EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
 428
 429 /**
 430  * cpuidle_unregister: unregister a driver and the devices. This function
 431  * can be used only if the driver has been previously registered through
 432  * the cpuidle_register function.
 433  *
 434  * @drv: a valid pointer to a struct cpuidle_driver
 435  */
 436 void cpuidle_unregister(struct cpuidle_driver *drv)
 437 {
 438         int cpu;
 439         struct cpuidle_device *device;
 440
 441         for_each_cpu(cpu, drv->cpumask) {
 442                 device = &per_cpu(cpuidle_dev, cpu);
 443                 cpuidle_unregister_device(device);
 444         }
 445
 446         cpuidle_unregister_driver(drv);
 447 }
 448 EXPORT_SYMBOL_GPL(cpuidle_unregister);
 449
 450 /**
 451  * cpuidle_register: registers the driver and the cpu devices with the
 452  * coupled_cpus passed as parameter. This function is used for all common
 453  * initialization pattern there are in the arch specific drivers. The
 454  * devices is globally defined in this file.
 455  *
 456  * @drv         : a valid pointer to a struct cpuidle_driver
 457  * @coupled_cpus: a cpumask for the coupled states
 458  *
 459  * Returns 0 on success, < 0 otherwise
 460  */
 461 int cpuidle_register(struct cpuidle_driver *drv,
 462                      const struct cpumask *const coupled_cpus)
 463 {
 464         int ret, cpu;
 465         struct cpuidle_device *device;
 466
 467         ret = cpuidle_register_driver(drv);
 468         if (ret) {
 469                 pr_err("failed to register cpuidle driver\n");
 470                 return ret;
 471         }
 472
 473         for_each_cpu(cpu, drv->cpumask) {
 474                 device = &per_cpu(cpuidle_dev, cpu);
 475                 device->cpu = cpu;
 476
 477 #ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
 478                 /*
 479                  * On multiplatform for ARM, the coupled idle states could be
 480                  * enabled in the kernel even if the cpuidle driver does not
 481                  * use it. Note, coupled_cpus is a struct copy.
 482                  */
 483                 if (coupled_cpus)
 484                         device->coupled_cpus = *coupled_cpus;
 485 #endif
 486                 ret = cpuidle_register_device(device);
 487                 if (!ret)
 488                         continue;
 489
 490                 pr_err("Failed to register cpuidle device for cpu%d\n", cpu);
 491
 492                 cpuidle_unregister(drv);
 493                 break;
 494         }
 495
 496         return ret;
 497 }
 498 EXPORT_SYMBOL_GPL(cpuidle_register);
 499
 500 #ifdef CONFIG_SMP
 501
 502 static void smp_callback(void *v)
 503 {
 504         /* we already woke the CPU up, nothing more to do */
 505 }
 506
 507 /*
 508  * This function gets called when a part of the kernel has a new latency
 509  * requirement.  This means we need to get all processors out of their C-state,
 510  * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
 511  * wakes them all right up.
 512  */
 513 static int cpuidle_latency_notify(struct notifier_block *b,
 514                 unsigned long l, void *v)
 515 {
 516         smp_call_function(smp_callback, NULL, 1);
 517         return NOTIFY_OK;
 518 }
 519
 520 static struct notifier_block cpuidle_latency_notifier = {
 521         .notifier_call = cpuidle_latency_notify,
 522 };
 523
 524 static inline void latency_notifier_init(struct notifier_block *n)
 525 {
 526         pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
 527 }
 528
 529 #else /* CONFIG_SMP */
 530
 531 #define latency_notifier_init(x) do { } while (0)
 532
 533 #endif /* CONFIG_SMP */
 534
 535 /**
 536  * cpuidle_init - core initializer
 537  */
 538 static int __init cpuidle_init(void)
 539 {
 540         int ret;
 541
 542         if (cpuidle_disabled())
 543                 return -ENODEV;
 544
 545         ret = cpuidle_add_interface(cpu_subsys.dev_root);
 546         if (ret)
 547                 return ret;
 548
 549         latency_notifier_init(&cpuidle_latency_notifier);
 550
 551         return 0;
 552 }
 553
 554 module_param(off, int, 0444);
 555 core_initcall(cpuidle_init);