2  * cpuidle.c - core cpuidle infrastructure
4  * (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
23 #include <linux/suspend.h>
24 #include <linux/tick.h>
51 	return off || !initialized || !drv || !dev || !dev->enabled;  in cpuidle_not_available()
55  * cpuidle_play_dead - cpu off-lining
57  * Returns in case of an error or no driver
66 		return -ENODEV;  in cpuidle_play_dead()
68 	/* Find lowest-power state that supports long-term idle */  in cpuidle_play_dead()
69 	for (i = drv->state_count - 1; i >= 0; i--)  in cpuidle_play_dead()
70 		if (drv->states[i].enter_dead)  in cpuidle_play_dead()
71 			return drv->states[i].enter_dead(dev, i);  in cpuidle_play_dead()
73 	return -ENODEV;  in cpuidle_play_dead()
85 	for (i = 1; i < drv->state_count; i++) {  in find_deepest_state()
86 		struct cpuidle_state *s = &drv->states[i];  in find_deepest_state()
87 		struct cpuidle_state_usage *su = &dev->states_usage[i];  in find_deepest_state()
89 		if (s->disabled || su->disable || s->exit_latency <= latency_req  in find_deepest_state()
90 		    || s->exit_latency > max_latency  in find_deepest_state()
91 		    || (s->flags & forbidden_flags)  in find_deepest_state()
92 		    || (s2idle && !s->enter_s2idle))  in find_deepest_state()
95 		latency_req = s->exit_latency;  in find_deepest_state()
102  * cpuidle_use_deepest_state - Set/clear governor override flag.
115 		dev->use_deepest_state = enable;  in cpuidle_use_deepest_state()
120  * cpuidle_find_deepest_state - Find the deepest available idle state.
140 	 * executing it contains RCU usage regarded as invalid in the idle  in enter_s2idle_proper()
150 	drv->states[index].enter_s2idle(dev, drv, index);  in enter_s2idle_proper()
155 	 * first CPU executing it calls functions containing RCU read-side  in enter_s2idle_proper()
163 	dev->states_usage[index].s2idle_time += ktime_us_delta(time_end, time_start);  in enter_s2idle_proper()
164 	dev->states_usage[index].s2idle_usage++;  in enter_s2idle_proper()
168  * cpuidle_enter_s2idle - Enter an idle state suitable for suspend-to-idle.
172  * If there are states with the ->enter_s2idle callback, find the deepest of
173  * them and enter it with frozen tick.
180 	 * Find the deepest state with ->enter_s2idle present, which guarantees  in cpuidle_enter_s2idle()
181 	 * that interrupts won't be enabled when it exits and allows the tick to  in cpuidle_enter_s2idle()
193  * cpuidle_enter_state - enter the state and update stats
196  * @index: index into the states table in @drv of the state to enter
203 	struct cpuidle_state *target_state = &drv->states[index];  in cpuidle_enter_state()
204 	bool broadcast = !!(target_state->flags & CPUIDLE_FLAG_TIMER_STOP);  in cpuidle_enter_state()
214 		index = find_deepest_state(drv, dev, target_state->exit_latency,  in cpuidle_enter_state()
218 			return -EBUSY;  in cpuidle_enter_state()
220 		target_state = &drv->states[index];  in cpuidle_enter_state()
227 	trace_cpu_idle_rcuidle(index, dev->cpu);  in cpuidle_enter_state()
231 	entered_state = target_state->enter(dev, drv, index);  in cpuidle_enter_state()
236 	trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);  in cpuidle_enter_state()
238 	/* The cpu is no longer idle or about to enter idle. */  in cpuidle_enter_state()
255 	dev->last_residency = (int) diff;  in cpuidle_enter_state()
260 		 * but that results in multiple copies of same code.  in cpuidle_enter_state()
262 		dev->states_usage[entered_state].time += dev->last_residency;  in cpuidle_enter_state()
263 		dev->states_usage[entered_state].usage++;  in cpuidle_enter_state()
265 		dev->last_residency = 0;  in cpuidle_enter_state()
272  * cpuidle_select - ask the cpuidle framework to choose an idle state
276  * @stop_tick: indication on whether or not to stop the tick
281  * 'false' boolean value if the scheduler tick should not be stopped before
287 	return cpuidle_curr_governor->select(drv, dev, stop_tick);  in cpuidle_select()
291  * cpuidle_enter - enter into the specified idle state
295  * @index: the index in the idle state table
297  * Returns the index in the idle state, < 0 in case of error.
309  * cpuidle_reflect - tell the underlying governor what was the state
310  * we were in
313  * @index: the index in the idle state table
318 	if (cpuidle_curr_governor->reflect && index >= 0)  in cpuidle_reflect()
319 		cpuidle_curr_governor->reflect(dev, index);  in cpuidle_reflect()
323  * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
335  * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
352  * cpuidle_pause_and_lock - temporarily disables CPUIDLE
363  * cpuidle_resume_and_unlock - resumes CPUIDLE operation
373 /* Currently used in suspend/resume path to suspend cpuidle */
381 /* Currently used in suspend/resume path to resume cpuidle */
390  * cpuidle_enable_device - enables idle PM for a CPU
402 		return -EINVAL;  in cpuidle_enable_device()
404 	if (dev->enabled)  in cpuidle_enable_device()
408 		return -EIO;  in cpuidle_enable_device()
413 		return -EIO;  in cpuidle_enable_device()
415 	if (!dev->registered)  in cpuidle_enable_device()
416 		return -EINVAL;  in cpuidle_enable_device()
422 	if (cpuidle_curr_governor->enable) {  in cpuidle_enable_device()
423 		ret = cpuidle_curr_governor->enable(drv, dev);  in cpuidle_enable_device()
430 	dev->enabled = 1;  in cpuidle_enable_device()
444  * cpuidle_disable_device - disables idle PM for a CPU
454 	if (!dev || !dev->enabled)  in cpuidle_disable_device()
460 	dev->enabled = 0;  in cpuidle_disable_device()
462 	if (cpuidle_curr_governor->disable)  in cpuidle_disable_device()
463 		cpuidle_curr_governor->disable(drv, dev);  in cpuidle_disable_device()
466 	enabled_devices--;  in cpuidle_disable_device()
475 	list_del(&dev->device_list);  in __cpuidle_unregister_device()
476 	per_cpu(cpuidle_devices, dev->cpu) = NULL;  in __cpuidle_unregister_device()
477 	module_put(drv->owner);  in __cpuidle_unregister_device()
479 	dev->registered = 0;  in __cpuidle_unregister_device()
484 	memset(dev->states_usage, 0, sizeof(dev->states_usage));  in __cpuidle_device_init()
485 	dev->last_residency = 0;  in __cpuidle_device_init()
489  * __cpuidle_register_device - internal register function called before register
500 	if (!try_module_get(drv->owner))  in __cpuidle_register_device()
501 		return -EINVAL;  in __cpuidle_register_device()
503 	per_cpu(cpuidle_devices, dev->cpu) = dev;  in __cpuidle_register_device()
504 	list_add(&dev->device_list, &cpuidle_detected_devices);  in __cpuidle_register_device()
510 		dev->registered = 1;  in __cpuidle_register_device()
516  * cpuidle_register_device - registers a CPU's idle PM feature
521 	int ret = -EBUSY;  in cpuidle_register_device()
524 		return -EINVAL;  in cpuidle_register_device()
528 	if (dev->registered)  in cpuidle_register_device()
562  * cpuidle_unregister_device - unregisters a CPU's idle PM feature
567 	if (!dev || dev->registered == 0)  in cpuidle_unregister_device()
597 	for_each_cpu(cpu, drv->cpumask) {  in cpuidle_unregister()
609  * initialization pattern there are in the arch specific drivers. The
610  * devices is globally defined in this file.
629 	for_each_cpu(cpu, drv->cpumask) {  in cpuidle_register()
631 		device->cpu = cpu;  in cpuidle_register()
636 		 * enabled in the kernel even if the cpuidle driver does not  in cpuidle_register()
640 			device->coupled_cpus = *coupled_cpus;  in cpuidle_register()
660  * requirement.  This means we need to get all processors out of their C-state,
661  * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
687  * cpuidle_init - core initializer
694 		return -ENODEV;  in cpuidle_init()