/* * cpuidle.c - core cpuidle infrastructure * * (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> * Shaohua Li <shaohua.li@intel.com> * Adam Belay <abelay@novell.com> * * This code is licenced under the GPL. */ #include <linux/kernel.h> #include <linux/mutex.h> #include <linux/sched.h> #include <linux/notifier.h> #include <linux/pm_qos.h> #include <linux/cpu.h> #include <linux/cpuidle.h> #include <linux/ktime.h> #include <linux/hrtimer.h> #include <linux/module.h> #include <trace/events/power.h> #include "cpuidle.h" DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices); DEFINE_MUTEX(cpuidle_lock); LIST_HEAD(cpuidle_detected_devices); static int enabled_devices; static int off __read_mostly; static int initialized __read_mostly; int cpuidle_disabled(void) { return off; } void disable_cpuidle(void) { off = 1; } #if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT) static void cpuidle_kick_cpus(void) { cpu_idle_wait(); } #elif defined(CONFIG_SMP) # error "Arch needs cpu_idle_wait() equivalent here" #else /* !CONFIG_ARCH_HAS_CPU_IDLE_WAIT && !CONFIG_SMP */ static void cpuidle_kick_cpus(void) {} #endif static int __cpuidle_register_device(struct cpuidle_device *dev); /** * cpuidle_idle_call - the main idle loop * * NOTE: no locks or semaphores should be used here * return non-zero on failure */ int cpuidle_idle_call(void) { struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices); struct cpuidle_driver *drv = cpuidle_get_driver(); struct cpuidle_state *target_state; int next_state, entered_state; if (off) return -ENODEV; if (!initialized) return -ENODEV; /* check if the device is ready */ if (!dev || !dev->enabled) return -EBUSY; #if 0 /* shows regressions, re-enable for 2.6.29 */ /* * run any timers that can be run now, at this point * before calculating the idle duration etc. */ hrtimer_peek_ahead_timers(); #endif /* ask the governor for the next state */ next_state = cpuidle_curr_governor->select(drv, dev); if (need_resched()) { local_irq_enable(); return 0; } target_state = &drv->states[next_state]; trace_power_start(POWER_CSTATE, next_state, dev->cpu); trace_cpu_idle(next_state, dev->cpu); entered_state = target_state->enter(dev, drv, next_state); trace_power_end(dev->cpu); trace_cpu_idle(PWR_EVENT_EXIT, dev->cpu); if (entered_state >= 0) { /* Update cpuidle counters */ /* This can be moved to within driver enter routine * but that results in multiple copies of same code. */ dev->states_usage[entered_state].time += (unsigned long long)dev->last_residency; dev->states_usage[entered_state].usage++; } /* give the governor an opportunity to reflect on the outcome */ if (cpuidle_curr_governor->reflect) cpuidle_curr_governor->reflect(dev, entered_state); return 0; } /** * cpuidle_install_idle_handler - installs the cpuidle idle loop handler */ void cpuidle_install_idle_handler(void) { if (enabled_devices) { /* Make sure all changes finished before we switch to new idle */ smp_wmb(); initialized = 1; } } /** * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler */ void cpuidle_uninstall_idle_handler(void) { if (enabled_devices) { initialized = 0; cpuidle_kick_cpus(); } } /** * cpuidle_pause_and_lock - temporarily disables CPUIDLE */ void cpuidle_pause_and_lock(void) { mutex_lock(&cpuidle_lock); cpuidle_uninstall_idle_handler(); } EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock); /** * cpuidle_resume_and_unlock - resumes CPUIDLE operation */ void cpuidle_resume_and_unlock(void) { cpuidle_install_idle_handler(); mutex_unlock(&cpuidle_lock); } EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock); #ifdef CONFIG_ARCH_HAS_CPU_RELAX static int poll_idle(struct cpuidle_device *dev, struct cpuidle_driver *drv, int index) { ktime_t t1, t2; s64 diff; t1 = ktime_get(); local_irq_enable(); while (!need_resched()) cpu_relax(); t2 = ktime_get(); diff = ktime_to_us(ktime_sub(t2, t1)); if (diff > INT_MAX) diff = INT_MAX; dev->last_residency = (int) diff; return index; } static void poll_idle_init(struct cpuidle_driver *drv) { struct cpuidle_state *state = &drv->states[0]; snprintf(state->name, CPUIDLE_NAME_LEN, "POLL"); snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE"); state->exit_latency = 0; state->target_residency = 0; state->power_usage = -1; state->flags = 0; state->enter = poll_idle; } #else static void poll_idle_init(struct cpuidle_driver *drv) {} #endif /* CONFIG_ARCH_HAS_CPU_RELAX */ /** * cpuidle_enable_device - enables idle PM for a CPU * @dev: the CPU * * This function must be called between cpuidle_pause_and_lock and * cpuidle_resume_and_unlock when used externally. */ int cpuidle_enable_device(struct cpuidle_device *dev) { int ret, i; if (dev->enabled) return 0; if (!cpuidle_get_driver() || !cpuidle_curr_governor) return -EIO; if (!dev->state_count) return -EINVAL; if (dev->registered == 0) { ret = __cpuidle_register_device(dev); if (ret) return ret; } poll_idle_init(cpuidle_get_driver()); if ((ret = cpuidle_add_state_sysfs(dev))) return ret; if (cpuidle_curr_governor->enable && (ret = cpuidle_curr_governor->enable(cpuidle_get_driver(), dev))) goto fail_sysfs; for (i = 0; i < dev->state_count; i++) { dev->states_usage[i].usage = 0; dev->states_usage[i].time = 0; } dev->last_residency = 0; smp_wmb(); dev->enabled = 1; enabled_devices++; return 0; fail_sysfs: cpuidle_remove_state_sysfs(dev); return ret; } EXPORT_SYMBOL_GPL(cpuidle_enable_device); /** * cpuidle_disable_device - disables idle PM for a CPU * @dev: the CPU * * This function must be called between cpuidle_pause_and_lock and * cpuidle_resume_and_unlock when used externally. */ void cpuidle_disable_device(struct cpuidle_device *dev) { if (!dev->enabled) return; if (!cpuidle_get_driver() || !cpuidle_curr_governor) return; dev->enabled = 0; if (cpuidle_curr_governor->disable) cpuidle_curr_governor->disable(cpuidle_get_driver(), dev); cpuidle_remove_state_sysfs(dev); enabled_devices--; } EXPORT_SYMBOL_GPL(cpuidle_disable_device); /** * __cpuidle_register_device - internal register function called before register * and enable routines * @dev: the cpu * * cpuidle_lock mutex must be held before this is called */ static int __cpuidle_register_device(struct cpuidle_device *dev) { int ret; struct device *cpu_dev = get_cpu_device((unsigned long)dev->cpu); struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver(); if (!dev) return -EINVAL; if (!try_module_get(cpuidle_driver->owner)) return -EINVAL; init_completion(&dev->kobj_unregister); per_cpu(cpuidle_devices, dev->cpu) = dev; list_add(&dev->device_list, &cpuidle_detected_devices); if ((ret = cpuidle_add_sysfs(cpu_dev))) { module_put(cpuidle_driver->owner); return ret; } dev->registered = 1; return 0; } /** * cpuidle_register_device - registers a CPU's idle PM feature * @dev: the cpu */ int cpuidle_register_device(struct cpuidle_device *dev) { int ret; mutex_lock(&cpuidle_lock); if ((ret = __cpuidle_register_device(dev))) { mutex_unlock(&cpuidle_lock); return ret; } cpuidle_enable_device(dev); cpuidle_install_idle_handler(); mutex_unlock(&cpuidle_lock); return 0; } EXPORT_SYMBOL_GPL(cpuidle_register_device); /** * cpuidle_unregister_device - unregisters a CPU's idle PM feature * @dev: the cpu */ void cpuidle_unregister_device(struct cpuidle_device *dev) { struct device *cpu_dev = get_cpu_device((unsigned long)dev->cpu); struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver(); if (dev->registered == 0) return; cpuidle_pause_and_lock(); cpuidle_disable_device(dev); cpuidle_remove_sysfs(cpu_dev); list_del(&dev->device_list); wait_for_completion(&dev->kobj_unregister); per_cpu(cpuidle_devices, dev->cpu) = NULL; cpuidle_resume_and_unlock(); module_put(cpuidle_driver->owner); } EXPORT_SYMBOL_GPL(cpuidle_unregister_device); #ifdef CONFIG_SMP static void smp_callback(void *v) { /* we already woke the CPU up, nothing more to do */ } /* * This function gets called when a part of the kernel has a new latency * requirement. This means we need to get all processors out of their C-state, * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that * wakes them all right up. */ static int cpuidle_latency_notify(struct notifier_block *b, unsigned long l, void *v) { smp_call_function(smp_callback, NULL, 1); return NOTIFY_OK; } static struct notifier_block cpuidle_latency_notifier = { .notifier_call = cpuidle_latency_notify, }; static inline void latency_notifier_init(struct notifier_block *n) { pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n); } #else /* CONFIG_SMP */ #define latency_notifier_init(x) do { } while (0) #endif /* CONFIG_SMP */ /** * cpuidle_init - core initializer */ static int __init cpuidle_init(void) { int ret; if (cpuidle_disabled()) return -ENODEV; ret = cpuidle_add_interface(cpu_subsys.dev_root); if (ret) return ret; latency_notifier_init(&cpuidle_latency_notifier); return 0; } module_param(off, int, 0444); core_initcall(cpuidle_init);