/* * 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/latency.h> #include <linux/cpu.h> #include <linux/cpuidle.h> #include "cpuidle.h" DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices); DEFINE_MUTEX(cpuidle_lock); LIST_HEAD(cpuidle_detected_devices); static void (*pm_idle_old)(void); static int enabled_devices; /** * cpuidle_idle_call - the main idle loop * * NOTE: no locks or semaphores should be used here */ static void cpuidle_idle_call(void) { struct cpuidle_device *dev = __get_cpu_var(cpuidle_devices); struct cpuidle_state *target_state; int next_state; /* check if the device is ready */ if (!dev || !dev->enabled) { if (pm_idle_old) pm_idle_old(); else local_irq_enable(); return; } /* ask the governor for the next state */ next_state = cpuidle_curr_governor->select(dev); if (need_resched()) return; target_state = &dev->states[next_state]; /* enter the state and update stats */ dev->last_residency = target_state->enter(dev, target_state); dev->last_state = target_state; target_state->time += dev->last_residency; target_state->usage++; /* give the governor an opportunity to reflect on the outcome */ if (cpuidle_curr_governor->reflect) cpuidle_curr_governor->reflect(dev); } /** * cpuidle_install_idle_handler - installs the cpuidle idle loop handler */ void cpuidle_install_idle_handler(void) { if (enabled_devices && (pm_idle != cpuidle_idle_call)) { /* Make sure all changes finished before we switch to new idle */ smp_wmb(); pm_idle = cpuidle_idle_call; } } /** * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler */ void cpuidle_uninstall_idle_handler(void) { if (enabled_devices && (pm_idle != pm_idle_old)) { pm_idle = pm_idle_old; cpu_idle_wait(); } } /** * 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); /** * 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_curr_driver || !cpuidle_curr_governor) return -EIO; if (!dev->state_count) return -EINVAL; if ((ret = cpuidle_add_state_sysfs(dev))) return ret; if (cpuidle_curr_governor->enable && (ret = cpuidle_curr_governor->enable(dev))) goto fail_sysfs; for (i = 0; i < dev->state_count; i++) { dev->states[i].usage = 0; dev->states[i].time = 0; } dev->last_residency = 0; dev->last_state = NULL; 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_curr_driver || !cpuidle_curr_governor) return; dev->enabled = 0; if (cpuidle_curr_governor->disable) cpuidle_curr_governor->disable(dev); cpuidle_remove_state_sysfs(dev); enabled_devices--; } EXPORT_SYMBOL_GPL(cpuidle_disable_device); /** * cpuidle_register_device - registers a CPU's idle PM feature * @dev: the cpu */ int cpuidle_register_device(struct cpuidle_device *dev) { int ret; struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu); if (!sys_dev) return -EINVAL; if (!try_module_get(cpuidle_curr_driver->owner)) return -EINVAL; init_completion(&dev->kobj_unregister); mutex_lock(&cpuidle_lock); per_cpu(cpuidle_devices, dev->cpu) = dev; list_add(&dev->device_list, &cpuidle_detected_devices); if ((ret = cpuidle_add_sysfs(sys_dev))) { mutex_unlock(&cpuidle_lock); module_put(cpuidle_curr_driver->owner); 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 sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu); cpuidle_pause_and_lock(); cpuidle_disable_device(dev); cpuidle_remove_sysfs(sys_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_curr_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, 0, 1); return NOTIFY_OK; } static struct notifier_block cpuidle_latency_notifier = { .notifier_call = cpuidle_latency_notify, }; #define latency_notifier_init(x) do { register_latency_notifier(x); } while (0) #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; pm_idle_old = pm_idle; ret = cpuidle_add_class_sysfs(&cpu_sysdev_class); if (ret) return ret; latency_notifier_init(&cpuidle_latency_notifier); return 0; } core_initcall(cpuidle_init);