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 /* ask the governor for the next state */ 78 next_state = cpuidle_curr_governor->select(dev); 79 if (need_resched()) { 80 local_irq_enable(); 81 return; 82 } 83 84 target_state = &dev->states[next_state]; 85 86 /* enter the state and update stats */ 87 dev->last_state = target_state; 88 dev->last_residency = target_state->enter(dev, target_state); 89 if (dev->last_state) 90 target_state = dev->last_state; 91 92 target_state->time += (unsigned long long)dev->last_residency; 93 target_state->usage++; 94 95 /* give the governor an opportunity to reflect on the outcome */ 96 if (cpuidle_curr_governor->reflect) 97 cpuidle_curr_governor->reflect(dev); 98 trace_power_end(0); 99 } 100 101 /** 102 * cpuidle_install_idle_handler - installs the cpuidle idle loop handler 103 */ 104 void cpuidle_install_idle_handler(void) 105 { 106 if (enabled_devices && (pm_idle != cpuidle_idle_call)) { 107 /* Make sure all changes finished before we switch to new idle */ 108 smp_wmb(); 109 pm_idle = cpuidle_idle_call; 110 } 111 } 112 113 /** 114 * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler 115 */ 116 void cpuidle_uninstall_idle_handler(void) 117 { 118 if (enabled_devices && pm_idle_old && (pm_idle != pm_idle_old)) { 119 pm_idle = pm_idle_old; 120 cpuidle_kick_cpus(); 121 } 122 } 123 124 /** 125 * cpuidle_pause_and_lock - temporarily disables CPUIDLE 126 */ 127 void cpuidle_pause_and_lock(void) 128 { 129 mutex_lock(&cpuidle_lock); 130 cpuidle_uninstall_idle_handler(); 131 } 132 133 EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock); 134 135 /** 136 * cpuidle_resume_and_unlock - resumes CPUIDLE operation 137 */ 138 void cpuidle_resume_and_unlock(void) 139 { 140 cpuidle_install_idle_handler(); 141 mutex_unlock(&cpuidle_lock); 142 } 143 144 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock); 145 146 /** 147 * cpuidle_enable_device - enables idle PM for a CPU 148 * @dev: the CPU 149 * 150 * This function must be called between cpuidle_pause_and_lock and 151 * cpuidle_resume_and_unlock when used externally. 152 */ 153 int cpuidle_enable_device(struct cpuidle_device *dev) 154 { 155 int ret, i; 156 157 if (dev->enabled) 158 return 0; 159 if (!cpuidle_get_driver() || !cpuidle_curr_governor) 160 return -EIO; 161 if (!dev->state_count) 162 return -EINVAL; 163 164 if (dev->registered == 0) { 165 ret = __cpuidle_register_device(dev); 166 if (ret) 167 return ret; 168 } 169 170 if ((ret = cpuidle_add_state_sysfs(dev))) 171 return ret; 172 173 if (cpuidle_curr_governor->enable && 174 (ret = cpuidle_curr_governor->enable(dev))) 175 goto fail_sysfs; 176 177 for (i = 0; i < dev->state_count; i++) { 178 dev->states[i].usage = 0; 179 dev->states[i].time = 0; 180 } 181 dev->last_residency = 0; 182 dev->last_state = NULL; 183 184 smp_wmb(); 185 186 dev->enabled = 1; 187 188 enabled_devices++; 189 return 0; 190 191 fail_sysfs: 192 cpuidle_remove_state_sysfs(dev); 193 194 return ret; 195 } 196 197 EXPORT_SYMBOL_GPL(cpuidle_enable_device); 198 199 /** 200 * cpuidle_disable_device - disables idle PM for a CPU 201 * @dev: the CPU 202 * 203 * This function must be called between cpuidle_pause_and_lock and 204 * cpuidle_resume_and_unlock when used externally. 205 */ 206 void cpuidle_disable_device(struct cpuidle_device *dev) 207 { 208 if (!dev->enabled) 209 return; 210 if (!cpuidle_get_driver() || !cpuidle_curr_governor) 211 return; 212 213 dev->enabled = 0; 214 215 if (cpuidle_curr_governor->disable) 216 cpuidle_curr_governor->disable(dev); 217 218 cpuidle_remove_state_sysfs(dev); 219 enabled_devices--; 220 } 221 222 EXPORT_SYMBOL_GPL(cpuidle_disable_device); 223 224 #ifdef CONFIG_ARCH_HAS_CPU_RELAX 225 static int poll_idle(struct cpuidle_device *dev, struct cpuidle_state *st) 226 { 227 ktime_t t1, t2; 228 s64 diff; 229 int ret; 230 231 t1 = ktime_get(); 232 local_irq_enable(); 233 while (!need_resched()) 234 cpu_relax(); 235 236 t2 = ktime_get(); 237 diff = ktime_to_us(ktime_sub(t2, t1)); 238 if (diff > INT_MAX) 239 diff = INT_MAX; 240 241 ret = (int) diff; 242 return ret; 243 } 244 245 static void poll_idle_init(struct cpuidle_device *dev) 246 { 247 struct cpuidle_state *state = &dev->states[0]; 248 249 cpuidle_set_statedata(state, NULL); 250 251 snprintf(state->name, CPUIDLE_NAME_LEN, "C0"); 252 snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE"); 253 state->exit_latency = 0; 254 state->target_residency = 0; 255 state->power_usage = -1; 256 state->flags = CPUIDLE_FLAG_POLL; 257 state->enter = poll_idle; 258 } 259 #else 260 static void poll_idle_init(struct cpuidle_device *dev) {} 261 #endif /* CONFIG_ARCH_HAS_CPU_RELAX */ 262 263 /** 264 * __cpuidle_register_device - internal register function called before register 265 * and enable routines 266 * @dev: the cpu 267 * 268 * cpuidle_lock mutex must be held before this is called 269 */ 270 static int __cpuidle_register_device(struct cpuidle_device *dev) 271 { 272 int ret; 273 struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu); 274 struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver(); 275 276 if (!sys_dev) 277 return -EINVAL; 278 if (!try_module_get(cpuidle_driver->owner)) 279 return -EINVAL; 280 281 init_completion(&dev->kobj_unregister); 282 283 poll_idle_init(dev); 284 285 per_cpu(cpuidle_devices, dev->cpu) = dev; 286 list_add(&dev->device_list, &cpuidle_detected_devices); 287 if ((ret = cpuidle_add_sysfs(sys_dev))) { 288 module_put(cpuidle_driver->owner); 289 return ret; 290 } 291 292 dev->registered = 1; 293 return 0; 294 } 295 296 /** 297 * cpuidle_register_device - registers a CPU's idle PM feature 298 * @dev: the cpu 299 */ 300 int cpuidle_register_device(struct cpuidle_device *dev) 301 { 302 int ret; 303 304 mutex_lock(&cpuidle_lock); 305 306 if ((ret = __cpuidle_register_device(dev))) { 307 mutex_unlock(&cpuidle_lock); 308 return ret; 309 } 310 311 cpuidle_enable_device(dev); 312 cpuidle_install_idle_handler(); 313 314 mutex_unlock(&cpuidle_lock); 315 316 return 0; 317 318 } 319 320 EXPORT_SYMBOL_GPL(cpuidle_register_device); 321 322 /** 323 * cpuidle_unregister_device - unregisters a CPU's idle PM feature 324 * @dev: the cpu 325 */ 326 void cpuidle_unregister_device(struct cpuidle_device *dev) 327 { 328 struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu); 329 struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver(); 330 331 if (dev->registered == 0) 332 return; 333 334 cpuidle_pause_and_lock(); 335 336 cpuidle_disable_device(dev); 337 338 cpuidle_remove_sysfs(sys_dev); 339 list_del(&dev->device_list); 340 wait_for_completion(&dev->kobj_unregister); 341 per_cpu(cpuidle_devices, dev->cpu) = NULL; 342 343 cpuidle_resume_and_unlock(); 344 345 module_put(cpuidle_driver->owner); 346 } 347 348 EXPORT_SYMBOL_GPL(cpuidle_unregister_device); 349 350 #ifdef CONFIG_SMP 351 352 static void smp_callback(void *v) 353 { 354 /* we already woke the CPU up, nothing more to do */ 355 } 356 357 /* 358 * This function gets called when a part of the kernel has a new latency 359 * requirement. This means we need to get all processors out of their C-state, 360 * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that 361 * wakes them all right up. 362 */ 363 static int cpuidle_latency_notify(struct notifier_block *b, 364 unsigned long l, void *v) 365 { 366 smp_call_function(smp_callback, NULL, 1); 367 return NOTIFY_OK; 368 } 369 370 static struct notifier_block cpuidle_latency_notifier = { 371 .notifier_call = cpuidle_latency_notify, 372 }; 373 374 static inline void latency_notifier_init(struct notifier_block *n) 375 { 376 pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n); 377 } 378 379 #else /* CONFIG_SMP */ 380 381 #define latency_notifier_init(x) do { } while (0) 382 383 #endif /* CONFIG_SMP */ 384 385 /** 386 * cpuidle_init - core initializer 387 */ 388 static int __init cpuidle_init(void) 389 { 390 int ret; 391 392 pm_idle_old = pm_idle; 393 394 ret = cpuidle_add_class_sysfs(&cpu_sysdev_class); 395 if (ret) 396 return ret; 397 398 latency_notifier_init(&cpuidle_latency_notifier); 399 400 return 0; 401 } 402 403 core_initcall(cpuidle_init); 404