drivers/cpuidle/cpuidle.c

   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(smp_processor_id());
  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);