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 #if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT) 44 static void cpuidle_kick_cpus(void) 45 { 46 cpu_idle_wait(); 47 } 48 #elif defined(CONFIG_SMP) 49 # error "Arch needs cpu_idle_wait() equivalent here" 50 #else /* !CONFIG_ARCH_HAS_CPU_IDLE_WAIT && !CONFIG_SMP */ 51 static void cpuidle_kick_cpus(void) {} 52 #endif 53 54 static int __cpuidle_register_device(struct cpuidle_device *dev); 55 56 static inline int cpuidle_enter(struct cpuidle_device *dev, 57 struct cpuidle_driver *drv, int index) 58 { 59 struct cpuidle_state *target_state = &drv->states[index]; 60 return target_state->enter(dev, drv, index); 61 } 62 63 static inline int cpuidle_enter_tk(struct cpuidle_device *dev, 64 struct cpuidle_driver *drv, int index) 65 { 66 return cpuidle_wrap_enter(dev, drv, index, cpuidle_enter); 67 } 68 69 typedef int (*cpuidle_enter_t)(struct cpuidle_device *dev, 70 struct cpuidle_driver *drv, int index); 71 72 static cpuidle_enter_t cpuidle_enter_ops; 73 74 /** 75 * cpuidle_play_dead - cpu off-lining 76 * 77 * Returns in case of an error or no driver 78 */ 79 int cpuidle_play_dead(void) 80 { 81 struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices); 82 struct cpuidle_driver *drv = cpuidle_get_driver(); 83 int i, dead_state = -1; 84 int power_usage = -1; 85 86 if (!drv) 87 return -ENODEV; 88 89 /* Find lowest-power state that supports long-term idle */ 90 for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) { 91 struct cpuidle_state *s = &drv->states[i]; 92 93 if (s->power_usage < power_usage && s->enter_dead) { 94 power_usage = s->power_usage; 95 dead_state = i; 96 } 97 } 98 99 if (dead_state != -1) 100 return drv->states[dead_state].enter_dead(dev, dead_state); 101 102 return -ENODEV; 103 } 104 105 /** 106 * cpuidle_idle_call - the main idle loop 107 * 108 * NOTE: no locks or semaphores should be used here 109 * return non-zero on failure 110 */ 111 int cpuidle_idle_call(void) 112 { 113 struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices); 114 struct cpuidle_driver *drv = cpuidle_get_driver(); 115 int next_state, entered_state; 116 117 if (off) 118 return -ENODEV; 119 120 if (!initialized) 121 return -ENODEV; 122 123 /* check if the device is ready */ 124 if (!dev || !dev->enabled) 125 return -EBUSY; 126 127 #if 0 128 /* shows regressions, re-enable for 2.6.29 */ 129 /* 130 * run any timers that can be run now, at this point 131 * before calculating the idle duration etc. 132 */ 133 hrtimer_peek_ahead_timers(); 134 #endif 135 136 /* ask the governor for the next state */ 137 next_state = cpuidle_curr_governor->select(drv, dev); 138 if (need_resched()) { 139 local_irq_enable(); 140 return 0; 141 } 142 143 trace_power_start_rcuidle(POWER_CSTATE, next_state, dev->cpu); 144 trace_cpu_idle_rcuidle(next_state, dev->cpu); 145 146 entered_state = cpuidle_enter_ops(dev, drv, next_state); 147 148 trace_power_end_rcuidle(dev->cpu); 149 trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu); 150 151 if (entered_state >= 0) { 152 /* Update cpuidle counters */ 153 /* This can be moved to within driver enter routine 154 * but that results in multiple copies of same code. 155 */ 156 dev->states_usage[entered_state].time += 157 (unsigned long long)dev->last_residency; 158 dev->states_usage[entered_state].usage++; 159 } else { 160 dev->last_residency = 0; 161 } 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 cpuidle_kick_cpus(); 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 /** 216 * cpuidle_wrap_enter - performs timekeeping and irqen around enter function 217 * @dev: pointer to a valid cpuidle_device object 218 * @drv: pointer to a valid cpuidle_driver object 219 * @index: index of the target cpuidle state. 220 */ 221 int cpuidle_wrap_enter(struct cpuidle_device *dev, 222 struct cpuidle_driver *drv, int index, 223 int (*enter)(struct cpuidle_device *dev, 224 struct cpuidle_driver *drv, int index)) 225 { 226 ktime_t time_start, time_end; 227 s64 diff; 228 229 time_start = ktime_get(); 230 231 index = enter(dev, drv, index); 232 233 time_end = ktime_get(); 234 235 local_irq_enable(); 236 237 diff = ktime_to_us(ktime_sub(time_end, time_start)); 238 if (diff > INT_MAX) 239 diff = INT_MAX; 240 241 dev->last_residency = (int) diff; 242 243 return index; 244 } 245 246 #ifdef CONFIG_ARCH_HAS_CPU_RELAX 247 static int poll_idle(struct cpuidle_device *dev, 248 struct cpuidle_driver *drv, int index) 249 { 250 ktime_t t1, t2; 251 s64 diff; 252 253 t1 = ktime_get(); 254 local_irq_enable(); 255 while (!need_resched()) 256 cpu_relax(); 257 258 t2 = ktime_get(); 259 diff = ktime_to_us(ktime_sub(t2, t1)); 260 if (diff > INT_MAX) 261 diff = INT_MAX; 262 263 dev->last_residency = (int) diff; 264 265 return index; 266 } 267 268 static void poll_idle_init(struct cpuidle_driver *drv) 269 { 270 struct cpuidle_state *state = &drv->states[0]; 271 272 snprintf(state->name, CPUIDLE_NAME_LEN, "POLL"); 273 snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE"); 274 state->exit_latency = 0; 275 state->target_residency = 0; 276 state->power_usage = -1; 277 state->flags = 0; 278 state->enter = poll_idle; 279 state->disable = 0; 280 } 281 #else 282 static void poll_idle_init(struct cpuidle_driver *drv) {} 283 #endif /* CONFIG_ARCH_HAS_CPU_RELAX */ 284 285 /** 286 * cpuidle_enable_device - enables idle PM for a CPU 287 * @dev: the CPU 288 * 289 * This function must be called between cpuidle_pause_and_lock and 290 * cpuidle_resume_and_unlock when used externally. 291 */ 292 int cpuidle_enable_device(struct cpuidle_device *dev) 293 { 294 int ret, i; 295 struct cpuidle_driver *drv = cpuidle_get_driver(); 296 297 if (dev->enabled) 298 return 0; 299 if (!drv || !cpuidle_curr_governor) 300 return -EIO; 301 if (!dev->state_count) 302 dev->state_count = drv->state_count; 303 304 if (dev->registered == 0) { 305 ret = __cpuidle_register_device(dev); 306 if (ret) 307 return ret; 308 } 309 310 cpuidle_enter_ops = drv->en_core_tk_irqen ? 311 cpuidle_enter_tk : cpuidle_enter; 312 313 poll_idle_init(drv); 314 315 if ((ret = cpuidle_add_state_sysfs(dev))) 316 return ret; 317 318 if (cpuidle_curr_governor->enable && 319 (ret = cpuidle_curr_governor->enable(drv, dev))) 320 goto fail_sysfs; 321 322 for (i = 0; i < dev->state_count; i++) { 323 dev->states_usage[i].usage = 0; 324 dev->states_usage[i].time = 0; 325 } 326 dev->last_residency = 0; 327 328 smp_wmb(); 329 330 dev->enabled = 1; 331 332 enabled_devices++; 333 return 0; 334 335 fail_sysfs: 336 cpuidle_remove_state_sysfs(dev); 337 338 return ret; 339 } 340 341 EXPORT_SYMBOL_GPL(cpuidle_enable_device); 342 343 /** 344 * cpuidle_disable_device - disables idle PM for a CPU 345 * @dev: the CPU 346 * 347 * This function must be called between cpuidle_pause_and_lock and 348 * cpuidle_resume_and_unlock when used externally. 349 */ 350 void cpuidle_disable_device(struct cpuidle_device *dev) 351 { 352 if (!dev->enabled) 353 return; 354 if (!cpuidle_get_driver() || !cpuidle_curr_governor) 355 return; 356 357 dev->enabled = 0; 358 359 if (cpuidle_curr_governor->disable) 360 cpuidle_curr_governor->disable(cpuidle_get_driver(), dev); 361 362 cpuidle_remove_state_sysfs(dev); 363 enabled_devices--; 364 } 365 366 EXPORT_SYMBOL_GPL(cpuidle_disable_device); 367 368 /** 369 * __cpuidle_register_device - internal register function called before register 370 * and enable routines 371 * @dev: the cpu 372 * 373 * cpuidle_lock mutex must be held before this is called 374 */ 375 static int __cpuidle_register_device(struct cpuidle_device *dev) 376 { 377 int ret; 378 struct device *cpu_dev = get_cpu_device((unsigned long)dev->cpu); 379 struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver(); 380 381 if (!dev) 382 return -EINVAL; 383 if (!try_module_get(cpuidle_driver->owner)) 384 return -EINVAL; 385 386 init_completion(&dev->kobj_unregister); 387 388 per_cpu(cpuidle_devices, dev->cpu) = dev; 389 list_add(&dev->device_list, &cpuidle_detected_devices); 390 if ((ret = cpuidle_add_sysfs(cpu_dev))) { 391 module_put(cpuidle_driver->owner); 392 return ret; 393 } 394 395 dev->registered = 1; 396 return 0; 397 } 398 399 /** 400 * cpuidle_register_device - registers a CPU's idle PM feature 401 * @dev: the cpu 402 */ 403 int cpuidle_register_device(struct cpuidle_device *dev) 404 { 405 int ret; 406 407 mutex_lock(&cpuidle_lock); 408 409 if ((ret = __cpuidle_register_device(dev))) { 410 mutex_unlock(&cpuidle_lock); 411 return ret; 412 } 413 414 cpuidle_enable_device(dev); 415 cpuidle_install_idle_handler(); 416 417 mutex_unlock(&cpuidle_lock); 418 419 return 0; 420 421 } 422 423 EXPORT_SYMBOL_GPL(cpuidle_register_device); 424 425 /** 426 * cpuidle_unregister_device - unregisters a CPU's idle PM feature 427 * @dev: the cpu 428 */ 429 void cpuidle_unregister_device(struct cpuidle_device *dev) 430 { 431 struct device *cpu_dev = get_cpu_device((unsigned long)dev->cpu); 432 struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver(); 433 434 if (dev->registered == 0) 435 return; 436 437 cpuidle_pause_and_lock(); 438 439 cpuidle_disable_device(dev); 440 441 cpuidle_remove_sysfs(cpu_dev); 442 list_del(&dev->device_list); 443 wait_for_completion(&dev->kobj_unregister); 444 per_cpu(cpuidle_devices, dev->cpu) = NULL; 445 446 cpuidle_resume_and_unlock(); 447 448 module_put(cpuidle_driver->owner); 449 } 450 451 EXPORT_SYMBOL_GPL(cpuidle_unregister_device); 452 453 #ifdef CONFIG_SMP 454 455 static void smp_callback(void *v) 456 { 457 /* we already woke the CPU up, nothing more to do */ 458 } 459 460 /* 461 * This function gets called when a part of the kernel has a new latency 462 * requirement. This means we need to get all processors out of their C-state, 463 * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that 464 * wakes them all right up. 465 */ 466 static int cpuidle_latency_notify(struct notifier_block *b, 467 unsigned long l, void *v) 468 { 469 smp_call_function(smp_callback, NULL, 1); 470 return NOTIFY_OK; 471 } 472 473 static struct notifier_block cpuidle_latency_notifier = { 474 .notifier_call = cpuidle_latency_notify, 475 }; 476 477 static inline void latency_notifier_init(struct notifier_block *n) 478 { 479 pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n); 480 } 481 482 #else /* CONFIG_SMP */ 483 484 #define latency_notifier_init(x) do { } while (0) 485 486 #endif /* CONFIG_SMP */ 487 488 /** 489 * cpuidle_init - core initializer 490 */ 491 static int __init cpuidle_init(void) 492 { 493 int ret; 494 495 if (cpuidle_disabled()) 496 return -ENODEV; 497 498 ret = cpuidle_add_interface(cpu_subsys.dev_root); 499 if (ret) 500 return ret; 501 502 latency_notifier_init(&cpuidle_latency_notifier); 503 504 return 0; 505 } 506 507 module_param(off, int, 0444); 508 core_initcall(cpuidle_init); 509