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