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 /** 57 * cpuidle_idle_call - the main idle loop 58 * 59 * NOTE: no locks or semaphores should be used here 60 * return non-zero on failure 61 */ 62 int cpuidle_idle_call(void) 63 { 64 struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices); 65 struct cpuidle_driver *drv = cpuidle_get_driver(); 66 struct cpuidle_state *target_state; 67 int next_state, entered_state; 68 69 if (off) 70 return -ENODEV; 71 72 if (!initialized) 73 return -ENODEV; 74 75 /* check if the device is ready */ 76 if (!dev || !dev->enabled) 77 return -EBUSY; 78 79 #if 0 80 /* shows regressions, re-enable for 2.6.29 */ 81 /* 82 * run any timers that can be run now, at this point 83 * before calculating the idle duration etc. 84 */ 85 hrtimer_peek_ahead_timers(); 86 #endif 87 88 /* ask the governor for the next state */ 89 next_state = cpuidle_curr_governor->select(drv, dev); 90 if (need_resched()) { 91 local_irq_enable(); 92 return 0; 93 } 94 95 target_state = &drv->states[next_state]; 96 97 trace_power_start_rcuidle(POWER_CSTATE, next_state, dev->cpu); 98 trace_cpu_idle_rcuidle(next_state, dev->cpu); 99 100 entered_state = target_state->enter(dev, drv, next_state); 101 102 trace_power_end_rcuidle(dev->cpu); 103 trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu); 104 105 if (entered_state >= 0) { 106 /* Update cpuidle counters */ 107 /* This can be moved to within driver enter routine 108 * but that results in multiple copies of same code. 109 */ 110 dev->states_usage[entered_state].time += 111 (unsigned long long)dev->last_residency; 112 dev->states_usage[entered_state].usage++; 113 } 114 115 /* give the governor an opportunity to reflect on the outcome */ 116 if (cpuidle_curr_governor->reflect) 117 cpuidle_curr_governor->reflect(dev, entered_state); 118 119 return 0; 120 } 121 122 /** 123 * cpuidle_install_idle_handler - installs the cpuidle idle loop handler 124 */ 125 void cpuidle_install_idle_handler(void) 126 { 127 if (enabled_devices) { 128 /* Make sure all changes finished before we switch to new idle */ 129 smp_wmb(); 130 initialized = 1; 131 } 132 } 133 134 /** 135 * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler 136 */ 137 void cpuidle_uninstall_idle_handler(void) 138 { 139 if (enabled_devices) { 140 initialized = 0; 141 cpuidle_kick_cpus(); 142 } 143 } 144 145 /** 146 * cpuidle_pause_and_lock - temporarily disables CPUIDLE 147 */ 148 void cpuidle_pause_and_lock(void) 149 { 150 mutex_lock(&cpuidle_lock); 151 cpuidle_uninstall_idle_handler(); 152 } 153 154 EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock); 155 156 /** 157 * cpuidle_resume_and_unlock - resumes CPUIDLE operation 158 */ 159 void cpuidle_resume_and_unlock(void) 160 { 161 cpuidle_install_idle_handler(); 162 mutex_unlock(&cpuidle_lock); 163 } 164 165 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock); 166 167 #ifdef CONFIG_ARCH_HAS_CPU_RELAX 168 static int poll_idle(struct cpuidle_device *dev, 169 struct cpuidle_driver *drv, int index) 170 { 171 ktime_t t1, t2; 172 s64 diff; 173 174 t1 = ktime_get(); 175 local_irq_enable(); 176 while (!need_resched()) 177 cpu_relax(); 178 179 t2 = ktime_get(); 180 diff = ktime_to_us(ktime_sub(t2, t1)); 181 if (diff > INT_MAX) 182 diff = INT_MAX; 183 184 dev->last_residency = (int) diff; 185 186 return index; 187 } 188 189 static void poll_idle_init(struct cpuidle_driver *drv) 190 { 191 struct cpuidle_state *state = &drv->states[0]; 192 193 snprintf(state->name, CPUIDLE_NAME_LEN, "POLL"); 194 snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE"); 195 state->exit_latency = 0; 196 state->target_residency = 0; 197 state->power_usage = -1; 198 state->flags = 0; 199 state->enter = poll_idle; 200 } 201 #else 202 static void poll_idle_init(struct cpuidle_driver *drv) {} 203 #endif /* CONFIG_ARCH_HAS_CPU_RELAX */ 204 205 /** 206 * cpuidle_enable_device - enables idle PM for a CPU 207 * @dev: the CPU 208 * 209 * This function must be called between cpuidle_pause_and_lock and 210 * cpuidle_resume_and_unlock when used externally. 211 */ 212 int cpuidle_enable_device(struct cpuidle_device *dev) 213 { 214 int ret, i; 215 216 if (dev->enabled) 217 return 0; 218 if (!cpuidle_get_driver() || !cpuidle_curr_governor) 219 return -EIO; 220 if (!dev->state_count) 221 return -EINVAL; 222 223 if (dev->registered == 0) { 224 ret = __cpuidle_register_device(dev); 225 if (ret) 226 return ret; 227 } 228 229 poll_idle_init(cpuidle_get_driver()); 230 231 if ((ret = cpuidle_add_state_sysfs(dev))) 232 return ret; 233 234 if (cpuidle_curr_governor->enable && 235 (ret = cpuidle_curr_governor->enable(cpuidle_get_driver(), dev))) 236 goto fail_sysfs; 237 238 for (i = 0; i < dev->state_count; i++) { 239 dev->states_usage[i].usage = 0; 240 dev->states_usage[i].time = 0; 241 } 242 dev->last_residency = 0; 243 244 smp_wmb(); 245 246 dev->enabled = 1; 247 248 enabled_devices++; 249 return 0; 250 251 fail_sysfs: 252 cpuidle_remove_state_sysfs(dev); 253 254 return ret; 255 } 256 257 EXPORT_SYMBOL_GPL(cpuidle_enable_device); 258 259 /** 260 * cpuidle_disable_device - disables idle PM for a CPU 261 * @dev: the CPU 262 * 263 * This function must be called between cpuidle_pause_and_lock and 264 * cpuidle_resume_and_unlock when used externally. 265 */ 266 void cpuidle_disable_device(struct cpuidle_device *dev) 267 { 268 if (!dev->enabled) 269 return; 270 if (!cpuidle_get_driver() || !cpuidle_curr_governor) 271 return; 272 273 dev->enabled = 0; 274 275 if (cpuidle_curr_governor->disable) 276 cpuidle_curr_governor->disable(cpuidle_get_driver(), dev); 277 278 cpuidle_remove_state_sysfs(dev); 279 enabled_devices--; 280 } 281 282 EXPORT_SYMBOL_GPL(cpuidle_disable_device); 283 284 /** 285 * __cpuidle_register_device - internal register function called before register 286 * and enable routines 287 * @dev: the cpu 288 * 289 * cpuidle_lock mutex must be held before this is called 290 */ 291 static int __cpuidle_register_device(struct cpuidle_device *dev) 292 { 293 int ret; 294 struct device *cpu_dev = get_cpu_device((unsigned long)dev->cpu); 295 struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver(); 296 297 if (!dev) 298 return -EINVAL; 299 if (!try_module_get(cpuidle_driver->owner)) 300 return -EINVAL; 301 302 init_completion(&dev->kobj_unregister); 303 304 per_cpu(cpuidle_devices, dev->cpu) = dev; 305 list_add(&dev->device_list, &cpuidle_detected_devices); 306 if ((ret = cpuidle_add_sysfs(cpu_dev))) { 307 module_put(cpuidle_driver->owner); 308 return ret; 309 } 310 311 dev->registered = 1; 312 return 0; 313 } 314 315 /** 316 * cpuidle_register_device - registers a CPU's idle PM feature 317 * @dev: the cpu 318 */ 319 int cpuidle_register_device(struct cpuidle_device *dev) 320 { 321 int ret; 322 323 mutex_lock(&cpuidle_lock); 324 325 if ((ret = __cpuidle_register_device(dev))) { 326 mutex_unlock(&cpuidle_lock); 327 return ret; 328 } 329 330 cpuidle_enable_device(dev); 331 cpuidle_install_idle_handler(); 332 333 mutex_unlock(&cpuidle_lock); 334 335 return 0; 336 337 } 338 339 EXPORT_SYMBOL_GPL(cpuidle_register_device); 340 341 /** 342 * cpuidle_unregister_device - unregisters a CPU's idle PM feature 343 * @dev: the cpu 344 */ 345 void cpuidle_unregister_device(struct cpuidle_device *dev) 346 { 347 struct device *cpu_dev = get_cpu_device((unsigned long)dev->cpu); 348 struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver(); 349 350 if (dev->registered == 0) 351 return; 352 353 cpuidle_pause_and_lock(); 354 355 cpuidle_disable_device(dev); 356 357 cpuidle_remove_sysfs(cpu_dev); 358 list_del(&dev->device_list); 359 wait_for_completion(&dev->kobj_unregister); 360 per_cpu(cpuidle_devices, dev->cpu) = NULL; 361 362 cpuidle_resume_and_unlock(); 363 364 module_put(cpuidle_driver->owner); 365 } 366 367 EXPORT_SYMBOL_GPL(cpuidle_unregister_device); 368 369 #ifdef CONFIG_SMP 370 371 static void smp_callback(void *v) 372 { 373 /* we already woke the CPU up, nothing more to do */ 374 } 375 376 /* 377 * This function gets called when a part of the kernel has a new latency 378 * requirement. This means we need to get all processors out of their C-state, 379 * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that 380 * wakes them all right up. 381 */ 382 static int cpuidle_latency_notify(struct notifier_block *b, 383 unsigned long l, void *v) 384 { 385 smp_call_function(smp_callback, NULL, 1); 386 return NOTIFY_OK; 387 } 388 389 static struct notifier_block cpuidle_latency_notifier = { 390 .notifier_call = cpuidle_latency_notify, 391 }; 392 393 static inline void latency_notifier_init(struct notifier_block *n) 394 { 395 pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n); 396 } 397 398 #else /* CONFIG_SMP */ 399 400 #define latency_notifier_init(x) do { } while (0) 401 402 #endif /* CONFIG_SMP */ 403 404 /** 405 * cpuidle_init - core initializer 406 */ 407 static int __init cpuidle_init(void) 408 { 409 int ret; 410 411 if (cpuidle_disabled()) 412 return -ENODEV; 413 414 ret = cpuidle_add_interface(cpu_subsys.dev_root); 415 if (ret) 416 return ret; 417 418 latency_notifier_init(&cpuidle_latency_notifier); 419 420 return 0; 421 } 422 423 module_param(off, int, 0444); 424 core_initcall(cpuidle_init); 425