| 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 <linux/suspend.h> |
| 23 | #include <linux/tick.h> |
| 24 | #include <trace/events/power.h> |
| 25 | |
| 26 | #include "cpuidle.h" |
| 27 | |
| 28 | DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices); |
| 29 | DEFINE_PER_CPU(struct cpuidle_device, cpuidle_dev); |
| 30 | |
| 31 | DEFINE_MUTEX(cpuidle_lock); |
| 32 | LIST_HEAD(cpuidle_detected_devices); |
| 33 | |
| 34 | static int enabled_devices; |
| 35 | static int off __read_mostly; |
| 36 | static int initialized __read_mostly; |
| 37 | |
| 38 | int cpuidle_disabled(void) |
| 39 | { |
| 40 | return off; |
| 41 | } |
| 42 | void disable_cpuidle(void) |
| 43 | { |
| 44 | off = 1; |
| 45 | } |
| 46 | |
| 47 | bool cpuidle_not_available(struct cpuidle_driver *drv, |
| 48 | struct cpuidle_device *dev) |
| 49 | { |
| 50 | return off || !initialized || !drv || !dev || !dev->enabled; |
| 51 | } |
| 52 | |
| 53 | /** |
| 54 | * cpuidle_play_dead - cpu off-lining |
| 55 | * |
| 56 | * Returns in case of an error or no driver |
| 57 | */ |
| 58 | int cpuidle_play_dead(void) |
| 59 | { |
| 60 | struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices); |
| 61 | struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); |
| 62 | int i; |
| 63 | |
| 64 | if (!drv) |
| 65 | return -ENODEV; |
| 66 | |
| 67 | /* Find lowest-power state that supports long-term idle */ |
| 68 | for (i = drv->state_count - 1; i >= 0; i--) |
| 69 | if (drv->states[i].enter_dead) |
| 70 | return drv->states[i].enter_dead(dev, i); |
| 71 | |
| 72 | return -ENODEV; |
| 73 | } |
| 74 | |
| 75 | static int find_deepest_state(struct cpuidle_driver *drv, |
| 76 | struct cpuidle_device *dev, |
| 77 | unsigned int max_latency, |
| 78 | unsigned int forbidden_flags, |
| 79 | bool freeze) |
| 80 | { |
| 81 | unsigned int latency_req = 0; |
| 82 | int i, ret = 0; |
| 83 | |
| 84 | for (i = 1; i < drv->state_count; i++) { |
| 85 | struct cpuidle_state *s = &drv->states[i]; |
| 86 | struct cpuidle_state_usage *su = &dev->states_usage[i]; |
| 87 | |
| 88 | if (s->disabled || su->disable || s->exit_latency <= latency_req |
| 89 | || s->exit_latency > max_latency |
| 90 | || (s->flags & forbidden_flags) |
| 91 | || (freeze && !s->enter_freeze)) |
| 92 | continue; |
| 93 | |
| 94 | latency_req = s->exit_latency; |
| 95 | ret = i; |
| 96 | } |
| 97 | return ret; |
| 98 | } |
| 99 | |
| 100 | #ifdef CONFIG_SUSPEND |
| 101 | /** |
| 102 | * cpuidle_find_deepest_state - Find the deepest available idle state. |
| 103 | * @drv: cpuidle driver for the given CPU. |
| 104 | * @dev: cpuidle device for the given CPU. |
| 105 | */ |
| 106 | int cpuidle_find_deepest_state(struct cpuidle_driver *drv, |
| 107 | struct cpuidle_device *dev) |
| 108 | { |
| 109 | return find_deepest_state(drv, dev, UINT_MAX, 0, false); |
| 110 | } |
| 111 | |
| 112 | static void enter_freeze_proper(struct cpuidle_driver *drv, |
| 113 | struct cpuidle_device *dev, int index) |
| 114 | { |
| 115 | /* |
| 116 | * trace_suspend_resume() called by tick_freeze() for the last CPU |
| 117 | * executing it contains RCU usage regarded as invalid in the idle |
| 118 | * context, so tell RCU about that. |
| 119 | */ |
| 120 | RCU_NONIDLE(tick_freeze()); |
| 121 | /* |
| 122 | * The state used here cannot be a "coupled" one, because the "coupled" |
| 123 | * cpuidle mechanism enables interrupts and doing that with timekeeping |
| 124 | * suspended is generally unsafe. |
| 125 | */ |
| 126 | stop_critical_timings(); |
| 127 | drv->states[index].enter_freeze(dev, drv, index); |
| 128 | WARN_ON(!irqs_disabled()); |
| 129 | /* |
| 130 | * timekeeping_resume() that will be called by tick_unfreeze() for the |
| 131 | * first CPU executing it calls functions containing RCU read-side |
| 132 | * critical sections, so tell RCU about that. |
| 133 | */ |
| 134 | RCU_NONIDLE(tick_unfreeze()); |
| 135 | start_critical_timings(); |
| 136 | } |
| 137 | |
| 138 | /** |
| 139 | * cpuidle_enter_freeze - Enter an idle state suitable for suspend-to-idle. |
| 140 | * @drv: cpuidle driver for the given CPU. |
| 141 | * @dev: cpuidle device for the given CPU. |
| 142 | * |
| 143 | * If there are states with the ->enter_freeze callback, find the deepest of |
| 144 | * them and enter it with frozen tick. |
| 145 | */ |
| 146 | int cpuidle_enter_freeze(struct cpuidle_driver *drv, struct cpuidle_device *dev) |
| 147 | { |
| 148 | int index; |
| 149 | |
| 150 | /* |
| 151 | * Find the deepest state with ->enter_freeze present, which guarantees |
| 152 | * that interrupts won't be enabled when it exits and allows the tick to |
| 153 | * be frozen safely. |
| 154 | */ |
| 155 | index = find_deepest_state(drv, dev, UINT_MAX, 0, true); |
| 156 | if (index > 0) |
| 157 | enter_freeze_proper(drv, dev, index); |
| 158 | |
| 159 | return index; |
| 160 | } |
| 161 | #endif /* CONFIG_SUSPEND */ |
| 162 | |
| 163 | /** |
| 164 | * cpuidle_enter_state - enter the state and update stats |
| 165 | * @dev: cpuidle device for this cpu |
| 166 | * @drv: cpuidle driver for this cpu |
| 167 | * @index: index into the states table in @drv of the state to enter |
| 168 | */ |
| 169 | int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv, |
| 170 | int index) |
| 171 | { |
| 172 | int entered_state; |
| 173 | |
| 174 | struct cpuidle_state *target_state = &drv->states[index]; |
| 175 | bool broadcast = !!(target_state->flags & CPUIDLE_FLAG_TIMER_STOP); |
| 176 | ktime_t time_start, time_end; |
| 177 | s64 diff; |
| 178 | |
| 179 | /* |
| 180 | * Tell the time framework to switch to a broadcast timer because our |
| 181 | * local timer will be shut down. If a local timer is used from another |
| 182 | * CPU as a broadcast timer, this call may fail if it is not available. |
| 183 | */ |
| 184 | if (broadcast && tick_broadcast_enter()) { |
| 185 | index = find_deepest_state(drv, dev, target_state->exit_latency, |
| 186 | CPUIDLE_FLAG_TIMER_STOP, false); |
| 187 | if (index < 0) { |
| 188 | default_idle_call(); |
| 189 | return -EBUSY; |
| 190 | } |
| 191 | target_state = &drv->states[index]; |
| 192 | } |
| 193 | |
| 194 | /* Take note of the planned idle state. */ |
| 195 | sched_idle_set_state(target_state); |
| 196 | |
| 197 | trace_cpu_idle_rcuidle(index, dev->cpu); |
| 198 | time_start = ns_to_ktime(local_clock()); |
| 199 | |
| 200 | stop_critical_timings(); |
| 201 | entered_state = target_state->enter(dev, drv, index); |
| 202 | start_critical_timings(); |
| 203 | |
| 204 | time_end = ns_to_ktime(local_clock()); |
| 205 | trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu); |
| 206 | |
| 207 | /* The cpu is no longer idle or about to enter idle. */ |
| 208 | sched_idle_set_state(NULL); |
| 209 | |
| 210 | if (broadcast) { |
| 211 | if (WARN_ON_ONCE(!irqs_disabled())) |
| 212 | local_irq_disable(); |
| 213 | |
| 214 | tick_broadcast_exit(); |
| 215 | } |
| 216 | |
| 217 | if (!cpuidle_state_is_coupled(drv, index)) |
| 218 | local_irq_enable(); |
| 219 | |
| 220 | diff = ktime_us_delta(time_end, time_start); |
| 221 | if (diff > INT_MAX) |
| 222 | diff = INT_MAX; |
| 223 | |
| 224 | dev->last_residency = (int) diff; |
| 225 | |
| 226 | if (entered_state >= 0) { |
| 227 | /* Update cpuidle counters */ |
| 228 | /* This can be moved to within driver enter routine |
| 229 | * but that results in multiple copies of same code. |
| 230 | */ |
| 231 | dev->states_usage[entered_state].time += dev->last_residency; |
| 232 | dev->states_usage[entered_state].usage++; |
| 233 | } else { |
| 234 | dev->last_residency = 0; |
| 235 | } |
| 236 | |
| 237 | return entered_state; |
| 238 | } |
| 239 | |
| 240 | /** |
| 241 | * cpuidle_select - ask the cpuidle framework to choose an idle state |
| 242 | * |
| 243 | * @drv: the cpuidle driver |
| 244 | * @dev: the cpuidle device |
| 245 | * |
| 246 | * Returns the index of the idle state. The return value must not be negative. |
| 247 | */ |
| 248 | int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) |
| 249 | { |
| 250 | return cpuidle_curr_governor->select(drv, dev); |
| 251 | } |
| 252 | |
| 253 | /** |
| 254 | * cpuidle_enter - enter into the specified idle state |
| 255 | * |
| 256 | * @drv: the cpuidle driver tied with the cpu |
| 257 | * @dev: the cpuidle device |
| 258 | * @index: the index in the idle state table |
| 259 | * |
| 260 | * Returns the index in the idle state, < 0 in case of error. |
| 261 | * The error code depends on the backend driver |
| 262 | */ |
| 263 | int cpuidle_enter(struct cpuidle_driver *drv, struct cpuidle_device *dev, |
| 264 | int index) |
| 265 | { |
| 266 | if (cpuidle_state_is_coupled(drv, index)) |
| 267 | return cpuidle_enter_state_coupled(dev, drv, index); |
| 268 | return cpuidle_enter_state(dev, drv, index); |
| 269 | } |
| 270 | |
| 271 | /** |
| 272 | * cpuidle_reflect - tell the underlying governor what was the state |
| 273 | * we were in |
| 274 | * |
| 275 | * @dev : the cpuidle device |
| 276 | * @index: the index in the idle state table |
| 277 | * |
| 278 | */ |
| 279 | void cpuidle_reflect(struct cpuidle_device *dev, int index) |
| 280 | { |
| 281 | if (cpuidle_curr_governor->reflect && index >= 0) |
| 282 | cpuidle_curr_governor->reflect(dev, index); |
| 283 | } |
| 284 | |
| 285 | /** |
| 286 | * cpuidle_install_idle_handler - installs the cpuidle idle loop handler |
| 287 | */ |
| 288 | void cpuidle_install_idle_handler(void) |
| 289 | { |
| 290 | if (enabled_devices) { |
| 291 | /* Make sure all changes finished before we switch to new idle */ |
| 292 | smp_wmb(); |
| 293 | initialized = 1; |
| 294 | } |
| 295 | } |
| 296 | |
| 297 | /** |
| 298 | * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler |
| 299 | */ |
| 300 | void cpuidle_uninstall_idle_handler(void) |
| 301 | { |
| 302 | if (enabled_devices) { |
| 303 | initialized = 0; |
| 304 | wake_up_all_idle_cpus(); |
| 305 | } |
| 306 | |
| 307 | /* |
| 308 | * Make sure external observers (such as the scheduler) |
| 309 | * are done looking at pointed idle states. |
| 310 | */ |
| 311 | synchronize_rcu(); |
| 312 | } |
| 313 | |
| 314 | /** |
| 315 | * cpuidle_pause_and_lock - temporarily disables CPUIDLE |
| 316 | */ |
| 317 | void cpuidle_pause_and_lock(void) |
| 318 | { |
| 319 | mutex_lock(&cpuidle_lock); |
| 320 | cpuidle_uninstall_idle_handler(); |
| 321 | } |
| 322 | |
| 323 | EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock); |
| 324 | |
| 325 | /** |
| 326 | * cpuidle_resume_and_unlock - resumes CPUIDLE operation |
| 327 | */ |
| 328 | void cpuidle_resume_and_unlock(void) |
| 329 | { |
| 330 | cpuidle_install_idle_handler(); |
| 331 | mutex_unlock(&cpuidle_lock); |
| 332 | } |
| 333 | |
| 334 | EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock); |
| 335 | |
| 336 | /* Currently used in suspend/resume path to suspend cpuidle */ |
| 337 | void cpuidle_pause(void) |
| 338 | { |
| 339 | mutex_lock(&cpuidle_lock); |
| 340 | cpuidle_uninstall_idle_handler(); |
| 341 | mutex_unlock(&cpuidle_lock); |
| 342 | } |
| 343 | |
| 344 | /* Currently used in suspend/resume path to resume cpuidle */ |
| 345 | void cpuidle_resume(void) |
| 346 | { |
| 347 | mutex_lock(&cpuidle_lock); |
| 348 | cpuidle_install_idle_handler(); |
| 349 | mutex_unlock(&cpuidle_lock); |
| 350 | } |
| 351 | |
| 352 | /** |
| 353 | * cpuidle_enable_device - enables idle PM for a CPU |
| 354 | * @dev: the CPU |
| 355 | * |
| 356 | * This function must be called between cpuidle_pause_and_lock and |
| 357 | * cpuidle_resume_and_unlock when used externally. |
| 358 | */ |
| 359 | int cpuidle_enable_device(struct cpuidle_device *dev) |
| 360 | { |
| 361 | int ret; |
| 362 | struct cpuidle_driver *drv; |
| 363 | |
| 364 | if (!dev) |
| 365 | return -EINVAL; |
| 366 | |
| 367 | if (dev->enabled) |
| 368 | return 0; |
| 369 | |
| 370 | drv = cpuidle_get_cpu_driver(dev); |
| 371 | |
| 372 | if (!drv || !cpuidle_curr_governor) |
| 373 | return -EIO; |
| 374 | |
| 375 | if (!dev->registered) |
| 376 | return -EINVAL; |
| 377 | |
| 378 | ret = cpuidle_add_device_sysfs(dev); |
| 379 | if (ret) |
| 380 | return ret; |
| 381 | |
| 382 | if (cpuidle_curr_governor->enable && |
| 383 | (ret = cpuidle_curr_governor->enable(drv, dev))) |
| 384 | goto fail_sysfs; |
| 385 | |
| 386 | smp_wmb(); |
| 387 | |
| 388 | dev->enabled = 1; |
| 389 | |
| 390 | enabled_devices++; |
| 391 | return 0; |
| 392 | |
| 393 | fail_sysfs: |
| 394 | cpuidle_remove_device_sysfs(dev); |
| 395 | |
| 396 | return ret; |
| 397 | } |
| 398 | |
| 399 | EXPORT_SYMBOL_GPL(cpuidle_enable_device); |
| 400 | |
| 401 | /** |
| 402 | * cpuidle_disable_device - disables idle PM for a CPU |
| 403 | * @dev: the CPU |
| 404 | * |
| 405 | * This function must be called between cpuidle_pause_and_lock and |
| 406 | * cpuidle_resume_and_unlock when used externally. |
| 407 | */ |
| 408 | void cpuidle_disable_device(struct cpuidle_device *dev) |
| 409 | { |
| 410 | struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); |
| 411 | |
| 412 | if (!dev || !dev->enabled) |
| 413 | return; |
| 414 | |
| 415 | if (!drv || !cpuidle_curr_governor) |
| 416 | return; |
| 417 | |
| 418 | dev->enabled = 0; |
| 419 | |
| 420 | if (cpuidle_curr_governor->disable) |
| 421 | cpuidle_curr_governor->disable(drv, dev); |
| 422 | |
| 423 | cpuidle_remove_device_sysfs(dev); |
| 424 | enabled_devices--; |
| 425 | } |
| 426 | |
| 427 | EXPORT_SYMBOL_GPL(cpuidle_disable_device); |
| 428 | |
| 429 | static void __cpuidle_unregister_device(struct cpuidle_device *dev) |
| 430 | { |
| 431 | struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); |
| 432 | |
| 433 | list_del(&dev->device_list); |
| 434 | per_cpu(cpuidle_devices, dev->cpu) = NULL; |
| 435 | module_put(drv->owner); |
| 436 | |
| 437 | dev->registered = 0; |
| 438 | } |
| 439 | |
| 440 | static void __cpuidle_device_init(struct cpuidle_device *dev) |
| 441 | { |
| 442 | memset(dev->states_usage, 0, sizeof(dev->states_usage)); |
| 443 | dev->last_residency = 0; |
| 444 | } |
| 445 | |
| 446 | /** |
| 447 | * __cpuidle_register_device - internal register function called before register |
| 448 | * and enable routines |
| 449 | * @dev: the cpu |
| 450 | * |
| 451 | * cpuidle_lock mutex must be held before this is called |
| 452 | */ |
| 453 | static int __cpuidle_register_device(struct cpuidle_device *dev) |
| 454 | { |
| 455 | int ret; |
| 456 | struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); |
| 457 | |
| 458 | if (!try_module_get(drv->owner)) |
| 459 | return -EINVAL; |
| 460 | |
| 461 | per_cpu(cpuidle_devices, dev->cpu) = dev; |
| 462 | list_add(&dev->device_list, &cpuidle_detected_devices); |
| 463 | |
| 464 | ret = cpuidle_coupled_register_device(dev); |
| 465 | if (ret) |
| 466 | __cpuidle_unregister_device(dev); |
| 467 | else |
| 468 | dev->registered = 1; |
| 469 | |
| 470 | return ret; |
| 471 | } |
| 472 | |
| 473 | /** |
| 474 | * cpuidle_register_device - registers a CPU's idle PM feature |
| 475 | * @dev: the cpu |
| 476 | */ |
| 477 | int cpuidle_register_device(struct cpuidle_device *dev) |
| 478 | { |
| 479 | int ret = -EBUSY; |
| 480 | |
| 481 | if (!dev) |
| 482 | return -EINVAL; |
| 483 | |
| 484 | mutex_lock(&cpuidle_lock); |
| 485 | |
| 486 | if (dev->registered) |
| 487 | goto out_unlock; |
| 488 | |
| 489 | __cpuidle_device_init(dev); |
| 490 | |
| 491 | ret = __cpuidle_register_device(dev); |
| 492 | if (ret) |
| 493 | goto out_unlock; |
| 494 | |
| 495 | ret = cpuidle_add_sysfs(dev); |
| 496 | if (ret) |
| 497 | goto out_unregister; |
| 498 | |
| 499 | ret = cpuidle_enable_device(dev); |
| 500 | if (ret) |
| 501 | goto out_sysfs; |
| 502 | |
| 503 | cpuidle_install_idle_handler(); |
| 504 | |
| 505 | out_unlock: |
| 506 | mutex_unlock(&cpuidle_lock); |
| 507 | |
| 508 | return ret; |
| 509 | |
| 510 | out_sysfs: |
| 511 | cpuidle_remove_sysfs(dev); |
| 512 | out_unregister: |
| 513 | __cpuidle_unregister_device(dev); |
| 514 | goto out_unlock; |
| 515 | } |
| 516 | |
| 517 | EXPORT_SYMBOL_GPL(cpuidle_register_device); |
| 518 | |
| 519 | /** |
| 520 | * cpuidle_unregister_device - unregisters a CPU's idle PM feature |
| 521 | * @dev: the cpu |
| 522 | */ |
| 523 | void cpuidle_unregister_device(struct cpuidle_device *dev) |
| 524 | { |
| 525 | if (!dev || dev->registered == 0) |
| 526 | return; |
| 527 | |
| 528 | cpuidle_pause_and_lock(); |
| 529 | |
| 530 | cpuidle_disable_device(dev); |
| 531 | |
| 532 | cpuidle_remove_sysfs(dev); |
| 533 | |
| 534 | __cpuidle_unregister_device(dev); |
| 535 | |
| 536 | cpuidle_coupled_unregister_device(dev); |
| 537 | |
| 538 | cpuidle_resume_and_unlock(); |
| 539 | } |
| 540 | |
| 541 | EXPORT_SYMBOL_GPL(cpuidle_unregister_device); |
| 542 | |
| 543 | /** |
| 544 | * cpuidle_unregister: unregister a driver and the devices. This function |
| 545 | * can be used only if the driver has been previously registered through |
| 546 | * the cpuidle_register function. |
| 547 | * |
| 548 | * @drv: a valid pointer to a struct cpuidle_driver |
| 549 | */ |
| 550 | void cpuidle_unregister(struct cpuidle_driver *drv) |
| 551 | { |
| 552 | int cpu; |
| 553 | struct cpuidle_device *device; |
| 554 | |
| 555 | for_each_cpu(cpu, drv->cpumask) { |
| 556 | device = &per_cpu(cpuidle_dev, cpu); |
| 557 | cpuidle_unregister_device(device); |
| 558 | } |
| 559 | |
| 560 | cpuidle_unregister_driver(drv); |
| 561 | } |
| 562 | EXPORT_SYMBOL_GPL(cpuidle_unregister); |
| 563 | |
| 564 | /** |
| 565 | * cpuidle_register: registers the driver and the cpu devices with the |
| 566 | * coupled_cpus passed as parameter. This function is used for all common |
| 567 | * initialization pattern there are in the arch specific drivers. The |
| 568 | * devices is globally defined in this file. |
| 569 | * |
| 570 | * @drv : a valid pointer to a struct cpuidle_driver |
| 571 | * @coupled_cpus: a cpumask for the coupled states |
| 572 | * |
| 573 | * Returns 0 on success, < 0 otherwise |
| 574 | */ |
| 575 | int cpuidle_register(struct cpuidle_driver *drv, |
| 576 | const struct cpumask *const coupled_cpus) |
| 577 | { |
| 578 | int ret, cpu; |
| 579 | struct cpuidle_device *device; |
| 580 | |
| 581 | ret = cpuidle_register_driver(drv); |
| 582 | if (ret) { |
| 583 | pr_err("failed to register cpuidle driver\n"); |
| 584 | return ret; |
| 585 | } |
| 586 | |
| 587 | for_each_cpu(cpu, drv->cpumask) { |
| 588 | device = &per_cpu(cpuidle_dev, cpu); |
| 589 | device->cpu = cpu; |
| 590 | |
| 591 | #ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED |
| 592 | /* |
| 593 | * On multiplatform for ARM, the coupled idle states could be |
| 594 | * enabled in the kernel even if the cpuidle driver does not |
| 595 | * use it. Note, coupled_cpus is a struct copy. |
| 596 | */ |
| 597 | if (coupled_cpus) |
| 598 | device->coupled_cpus = *coupled_cpus; |
| 599 | #endif |
| 600 | ret = cpuidle_register_device(device); |
| 601 | if (!ret) |
| 602 | continue; |
| 603 | |
| 604 | pr_err("Failed to register cpuidle device for cpu%d\n", cpu); |
| 605 | |
| 606 | cpuidle_unregister(drv); |
| 607 | break; |
| 608 | } |
| 609 | |
| 610 | return ret; |
| 611 | } |
| 612 | EXPORT_SYMBOL_GPL(cpuidle_register); |
| 613 | |
| 614 | #ifdef CONFIG_SMP |
| 615 | |
| 616 | /* |
| 617 | * This function gets called when a part of the kernel has a new latency |
| 618 | * requirement. This means we need to get all processors out of their C-state, |
| 619 | * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that |
| 620 | * wakes them all right up. |
| 621 | */ |
| 622 | static int cpuidle_latency_notify(struct notifier_block *b, |
| 623 | unsigned long l, void *v) |
| 624 | { |
| 625 | wake_up_all_idle_cpus(); |
| 626 | return NOTIFY_OK; |
| 627 | } |
| 628 | |
| 629 | static struct notifier_block cpuidle_latency_notifier = { |
| 630 | .notifier_call = cpuidle_latency_notify, |
| 631 | }; |
| 632 | |
| 633 | static inline void latency_notifier_init(struct notifier_block *n) |
| 634 | { |
| 635 | pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n); |
| 636 | } |
| 637 | |
| 638 | #else /* CONFIG_SMP */ |
| 639 | |
| 640 | #define latency_notifier_init(x) do { } while (0) |
| 641 | |
| 642 | #endif /* CONFIG_SMP */ |
| 643 | |
| 644 | /** |
| 645 | * cpuidle_init - core initializer |
| 646 | */ |
| 647 | static int __init cpuidle_init(void) |
| 648 | { |
| 649 | int ret; |
| 650 | |
| 651 | if (cpuidle_disabled()) |
| 652 | return -ENODEV; |
| 653 | |
| 654 | ret = cpuidle_add_interface(cpu_subsys.dev_root); |
| 655 | if (ret) |
| 656 | return ret; |
| 657 | |
| 658 | latency_notifier_init(&cpuidle_latency_notifier); |
| 659 | |
| 660 | return 0; |
| 661 | } |
| 662 | |
| 663 | module_param(off, int, 0444); |
| 664 | core_initcall(cpuidle_init); |