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                 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);