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_params.h> 16 #include <linux/cpu.h> 17 #include <linux/cpuidle.h> 18 #include <linux/ktime.h> 19 #include <linux/hrtimer.h> 20 #include <trace/events/power.h> 21 22 #include "cpuidle.h" 23 24 DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices); 25 26 DEFINE_MUTEX(cpuidle_lock); 27 LIST_HEAD(cpuidle_detected_devices); 28 static void (*pm_idle_old)(void); 29 30 static int enabled_devices; 31 32 #if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT) 33 static void cpuidle_kick_cpus(void) 34 { 35 cpu_idle_wait(); 36 } 37 #elif defined(CONFIG_SMP) 38 # error "Arch needs cpu_idle_wait() equivalent here" 39 #else /* !CONFIG_ARCH_HAS_CPU_IDLE_WAIT && !CONFIG_SMP */ 40 static void cpuidle_kick_cpus(void) {} 41 #endif 42 43 static int __cpuidle_register_device(struct cpuidle_device *dev); 44 45 /** 46 * cpuidle_idle_call - the main idle loop 47 * 48 * NOTE: no locks or semaphores should be used here 49 */ 50 static void cpuidle_idle_call(void) 51 { 52 struct cpuidle_device *dev = __get_cpu_var(cpuidle_devices); 53 struct cpuidle_state *target_state; 54 int next_state; 55 56 /* check if the device is ready */ 57 if (!dev || !dev->enabled) { 58 if (pm_idle_old) 59 pm_idle_old(); 60 else 61 #if defined(CONFIG_ARCH_HAS_DEFAULT_IDLE) 62 default_idle(); 63 #else 64 local_irq_enable(); 65 #endif 66 return; 67 } 68 69 #if 0 70 /* shows regressions, re-enable for 2.6.29 */ 71 /* 72 * run any timers that can be run now, at this point 73 * before calculating the idle duration etc. 74 */ 75 hrtimer_peek_ahead_timers(); 76 #endif 77 78 /* 79 * Call the device's prepare function before calling the 80 * governor's select function. ->prepare gives the device's 81 * cpuidle driver a chance to update any dynamic information 82 * of its cpuidle states for the current idle period, e.g. 83 * state availability, latencies, residencies, etc. 84 */ 85 if (dev->prepare) 86 dev->prepare(dev); 87 88 /* ask the governor for the next state */ 89 next_state = cpuidle_curr_governor->select(dev); 90 if (need_resched()) { 91 local_irq_enable(); 92 return; 93 } 94 95 target_state = &dev->states[next_state]; 96 97 /* enter the state and update stats */ 98 dev->last_state = target_state; 99 dev->last_residency = target_state->enter(dev, target_state); 100 if (dev->last_state) 101 target_state = dev->last_state; 102 103 target_state->time += (unsigned long long)dev->last_residency; 104 target_state->usage++; 105 106 /* give the governor an opportunity to reflect on the outcome */ 107 if (cpuidle_curr_governor->reflect) 108 cpuidle_curr_governor->reflect(dev); 109 trace_power_end(smp_processor_id()); 110 trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id()); 111 } 112 113 /** 114 * cpuidle_install_idle_handler - installs the cpuidle idle loop handler 115 */ 116 void cpuidle_install_idle_handler(void) 117 { 118 if (enabled_devices && (pm_idle != cpuidle_idle_call)) { 119 /* Make sure all changes finished before we switch to new idle */ 120 smp_wmb(); 121 pm_idle = cpuidle_idle_call; 122 } 123 } 124 125 /** 126 * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler 127 */ 128 void cpuidle_uninstall_idle_handler(void) 129 { 130 if (enabled_devices && pm_idle_old && (pm_idle != pm_idle_old)) { 131 pm_idle = pm_idle_old; 132 cpuidle_kick_cpus(); 133 } 134 } 135 136 /** 137 * cpuidle_pause_and_lock - temporarily disables CPUIDLE 138 */ 139 void cpuidle_pause_and_lock(void) 140 { 141 mutex_lock(&cpuidle_lock); 142 cpuidle_uninstall_idle_handler(); 143 } 144 145 EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock); 146 147 /** 148 * cpuidle_resume_and_unlock - resumes CPUIDLE operation 149 */ 150 void cpuidle_resume_and_unlock(void) 151 { 152 cpuidle_install_idle_handler(); 153 mutex_unlock(&cpuidle_lock); 154 } 155 156 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock); 157 158 /** 159 * cpuidle_enable_device - enables idle PM for a CPU 160 * @dev: the CPU 161 * 162 * This function must be called between cpuidle_pause_and_lock and 163 * cpuidle_resume_and_unlock when used externally. 164 */ 165 int cpuidle_enable_device(struct cpuidle_device *dev) 166 { 167 int ret, i; 168 169 if (dev->enabled) 170 return 0; 171 if (!cpuidle_get_driver() || !cpuidle_curr_governor) 172 return -EIO; 173 if (!dev->state_count) 174 return -EINVAL; 175 176 if (dev->registered == 0) { 177 ret = __cpuidle_register_device(dev); 178 if (ret) 179 return ret; 180 } 181 182 if ((ret = cpuidle_add_state_sysfs(dev))) 183 return ret; 184 185 if (cpuidle_curr_governor->enable && 186 (ret = cpuidle_curr_governor->enable(dev))) 187 goto fail_sysfs; 188 189 for (i = 0; i < dev->state_count; i++) { 190 dev->states[i].usage = 0; 191 dev->states[i].time = 0; 192 } 193 dev->last_residency = 0; 194 dev->last_state = NULL; 195 196 smp_wmb(); 197 198 dev->enabled = 1; 199 200 enabled_devices++; 201 return 0; 202 203 fail_sysfs: 204 cpuidle_remove_state_sysfs(dev); 205 206 return ret; 207 } 208 209 EXPORT_SYMBOL_GPL(cpuidle_enable_device); 210 211 /** 212 * cpuidle_disable_device - disables idle PM for a CPU 213 * @dev: the CPU 214 * 215 * This function must be called between cpuidle_pause_and_lock and 216 * cpuidle_resume_and_unlock when used externally. 217 */ 218 void cpuidle_disable_device(struct cpuidle_device *dev) 219 { 220 if (!dev->enabled) 221 return; 222 if (!cpuidle_get_driver() || !cpuidle_curr_governor) 223 return; 224 225 dev->enabled = 0; 226 227 if (cpuidle_curr_governor->disable) 228 cpuidle_curr_governor->disable(dev); 229 230 cpuidle_remove_state_sysfs(dev); 231 enabled_devices--; 232 } 233 234 EXPORT_SYMBOL_GPL(cpuidle_disable_device); 235 236 #ifdef CONFIG_ARCH_HAS_CPU_RELAX 237 static int poll_idle(struct cpuidle_device *dev, struct cpuidle_state *st) 238 { 239 ktime_t t1, t2; 240 s64 diff; 241 int ret; 242 243 t1 = ktime_get(); 244 local_irq_enable(); 245 while (!need_resched()) 246 cpu_relax(); 247 248 t2 = ktime_get(); 249 diff = ktime_to_us(ktime_sub(t2, t1)); 250 if (diff > INT_MAX) 251 diff = INT_MAX; 252 253 ret = (int) diff; 254 return ret; 255 } 256 257 static void poll_idle_init(struct cpuidle_device *dev) 258 { 259 struct cpuidle_state *state = &dev->states[0]; 260 261 cpuidle_set_statedata(state, NULL); 262 263 snprintf(state->name, CPUIDLE_NAME_LEN, "C0"); 264 snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE"); 265 state->exit_latency = 0; 266 state->target_residency = 0; 267 state->power_usage = -1; 268 state->flags = CPUIDLE_FLAG_POLL; 269 state->enter = poll_idle; 270 } 271 #else 272 static void poll_idle_init(struct cpuidle_device *dev) {} 273 #endif /* CONFIG_ARCH_HAS_CPU_RELAX */ 274 275 /** 276 * __cpuidle_register_device - internal register function called before register 277 * and enable routines 278 * @dev: the cpu 279 * 280 * cpuidle_lock mutex must be held before this is called 281 */ 282 static int __cpuidle_register_device(struct cpuidle_device *dev) 283 { 284 int ret; 285 struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu); 286 struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver(); 287 288 if (!sys_dev) 289 return -EINVAL; 290 if (!try_module_get(cpuidle_driver->owner)) 291 return -EINVAL; 292 293 init_completion(&dev->kobj_unregister); 294 295 poll_idle_init(dev); 296 297 /* 298 * cpuidle driver should set the dev->power_specified bit 299 * before registering the device if the driver provides 300 * power_usage numbers. 301 * 302 * For those devices whose ->power_specified is not set, 303 * we fill in power_usage with decreasing values as the 304 * cpuidle code has an implicit assumption that state Cn 305 * uses less power than C(n-1). 306 * 307 * With CONFIG_ARCH_HAS_CPU_RELAX, C0 is already assigned 308 * an power value of -1. So we use -2, -3, etc, for other 309 * c-states. 310 */ 311 if (!dev->power_specified) { 312 int i; 313 for (i = CPUIDLE_DRIVER_STATE_START; i < dev->state_count; i++) 314 dev->states[i].power_usage = -1 - i; 315 } 316 317 per_cpu(cpuidle_devices, dev->cpu) = dev; 318 list_add(&dev->device_list, &cpuidle_detected_devices); 319 if ((ret = cpuidle_add_sysfs(sys_dev))) { 320 module_put(cpuidle_driver->owner); 321 return ret; 322 } 323 324 dev->registered = 1; 325 return 0; 326 } 327 328 /** 329 * cpuidle_register_device - registers a CPU's idle PM feature 330 * @dev: the cpu 331 */ 332 int cpuidle_register_device(struct cpuidle_device *dev) 333 { 334 int ret; 335 336 mutex_lock(&cpuidle_lock); 337 338 if ((ret = __cpuidle_register_device(dev))) { 339 mutex_unlock(&cpuidle_lock); 340 return ret; 341 } 342 343 cpuidle_enable_device(dev); 344 cpuidle_install_idle_handler(); 345 346 mutex_unlock(&cpuidle_lock); 347 348 return 0; 349 350 } 351 352 EXPORT_SYMBOL_GPL(cpuidle_register_device); 353 354 /** 355 * cpuidle_unregister_device - unregisters a CPU's idle PM feature 356 * @dev: the cpu 357 */ 358 void cpuidle_unregister_device(struct cpuidle_device *dev) 359 { 360 struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu); 361 struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver(); 362 363 if (dev->registered == 0) 364 return; 365 366 cpuidle_pause_and_lock(); 367 368 cpuidle_disable_device(dev); 369 370 cpuidle_remove_sysfs(sys_dev); 371 list_del(&dev->device_list); 372 wait_for_completion(&dev->kobj_unregister); 373 per_cpu(cpuidle_devices, dev->cpu) = NULL; 374 375 cpuidle_resume_and_unlock(); 376 377 module_put(cpuidle_driver->owner); 378 } 379 380 EXPORT_SYMBOL_GPL(cpuidle_unregister_device); 381 382 #ifdef CONFIG_SMP 383 384 static void smp_callback(void *v) 385 { 386 /* we already woke the CPU up, nothing more to do */ 387 } 388 389 /* 390 * This function gets called when a part of the kernel has a new latency 391 * requirement. This means we need to get all processors out of their C-state, 392 * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that 393 * wakes them all right up. 394 */ 395 static int cpuidle_latency_notify(struct notifier_block *b, 396 unsigned long l, void *v) 397 { 398 smp_call_function(smp_callback, NULL, 1); 399 return NOTIFY_OK; 400 } 401 402 static struct notifier_block cpuidle_latency_notifier = { 403 .notifier_call = cpuidle_latency_notify, 404 }; 405 406 static inline void latency_notifier_init(struct notifier_block *n) 407 { 408 pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n); 409 } 410 411 #else /* CONFIG_SMP */ 412 413 #define latency_notifier_init(x) do { } while (0) 414 415 #endif /* CONFIG_SMP */ 416 417 /** 418 * cpuidle_init - core initializer 419 */ 420 static int __init cpuidle_init(void) 421 { 422 int ret; 423 424 pm_idle_old = pm_idle; 425 426 ret = cpuidle_add_class_sysfs(&cpu_sysdev_class); 427 if (ret) 428 return ret; 429 430 latency_notifier_init(&cpuidle_latency_notifier); 431 432 return 0; 433 } 434 435 core_initcall(cpuidle_init); 436