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380 lines
8.1 KiB
380 lines
8.1 KiB
/*
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* cpuidle.c - core cpuidle infrastructure
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*
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* (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
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* Shaohua Li <shaohua.li@intel.com>
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* Adam Belay <abelay@novell.com>
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*
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* This code is licenced under the GPL.
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*/
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#include <linux/kernel.h>
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#include <linux/mutex.h>
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#include <linux/sched.h>
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#include <linux/notifier.h>
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#include <linux/pm_qos_params.h>
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#include <linux/cpu.h>
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#include <linux/cpuidle.h>
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#include <linux/ktime.h>
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#include "cpuidle.h"
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DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
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DEFINE_MUTEX(cpuidle_lock);
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LIST_HEAD(cpuidle_detected_devices);
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static void (*pm_idle_old)(void);
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static int enabled_devices;
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#if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT)
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static void cpuidle_kick_cpus(void)
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{
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cpu_idle_wait();
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}
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#elif defined(CONFIG_SMP)
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# error "Arch needs cpu_idle_wait() equivalent here"
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#else /* !CONFIG_ARCH_HAS_CPU_IDLE_WAIT && !CONFIG_SMP */
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static void cpuidle_kick_cpus(void) {}
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#endif
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static int __cpuidle_register_device(struct cpuidle_device *dev);
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/**
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* cpuidle_idle_call - the main idle loop
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*
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* NOTE: no locks or semaphores should be used here
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*/
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static void cpuidle_idle_call(void)
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{
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struct cpuidle_device *dev = __get_cpu_var(cpuidle_devices);
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struct cpuidle_state *target_state;
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int next_state;
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/* check if the device is ready */
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if (!dev || !dev->enabled) {
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if (pm_idle_old)
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pm_idle_old();
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else
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local_irq_enable();
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return;
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}
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/* ask the governor for the next state */
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next_state = cpuidle_curr_governor->select(dev);
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if (need_resched())
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return;
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target_state = &dev->states[next_state];
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/* enter the state and update stats */
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dev->last_residency = target_state->enter(dev, target_state);
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dev->last_state = target_state;
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target_state->time += (unsigned long long)dev->last_residency;
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target_state->usage++;
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/* give the governor an opportunity to reflect on the outcome */
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if (cpuidle_curr_governor->reflect)
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cpuidle_curr_governor->reflect(dev);
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}
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/**
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* cpuidle_install_idle_handler - installs the cpuidle idle loop handler
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*/
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void cpuidle_install_idle_handler(void)
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{
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if (enabled_devices && (pm_idle != cpuidle_idle_call)) {
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/* Make sure all changes finished before we switch to new idle */
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smp_wmb();
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pm_idle = cpuidle_idle_call;
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}
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}
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/**
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* cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
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*/
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void cpuidle_uninstall_idle_handler(void)
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{
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if (enabled_devices && pm_idle_old && (pm_idle != pm_idle_old)) {
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pm_idle = pm_idle_old;
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cpuidle_kick_cpus();
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}
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}
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/**
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* cpuidle_pause_and_lock - temporarily disables CPUIDLE
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*/
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void cpuidle_pause_and_lock(void)
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{
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mutex_lock(&cpuidle_lock);
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cpuidle_uninstall_idle_handler();
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}
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EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
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/**
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* cpuidle_resume_and_unlock - resumes CPUIDLE operation
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*/
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void cpuidle_resume_and_unlock(void)
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{
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cpuidle_install_idle_handler();
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mutex_unlock(&cpuidle_lock);
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}
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EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
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/**
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* cpuidle_enable_device - enables idle PM for a CPU
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* @dev: the CPU
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*
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* This function must be called between cpuidle_pause_and_lock and
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* cpuidle_resume_and_unlock when used externally.
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*/
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int cpuidle_enable_device(struct cpuidle_device *dev)
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{
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int ret, i;
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if (dev->enabled)
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return 0;
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if (!cpuidle_curr_driver || !cpuidle_curr_governor)
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return -EIO;
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if (!dev->state_count)
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return -EINVAL;
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if (dev->registered == 0) {
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ret = __cpuidle_register_device(dev);
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if (ret)
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return ret;
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}
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if ((ret = cpuidle_add_state_sysfs(dev)))
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return ret;
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if (cpuidle_curr_governor->enable &&
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(ret = cpuidle_curr_governor->enable(dev)))
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goto fail_sysfs;
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for (i = 0; i < dev->state_count; i++) {
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dev->states[i].usage = 0;
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dev->states[i].time = 0;
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}
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dev->last_residency = 0;
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dev->last_state = NULL;
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smp_wmb();
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dev->enabled = 1;
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enabled_devices++;
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return 0;
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fail_sysfs:
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cpuidle_remove_state_sysfs(dev);
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return ret;
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}
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EXPORT_SYMBOL_GPL(cpuidle_enable_device);
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/**
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* cpuidle_disable_device - disables idle PM for a CPU
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* @dev: the CPU
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*
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* This function must be called between cpuidle_pause_and_lock and
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* cpuidle_resume_and_unlock when used externally.
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*/
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void cpuidle_disable_device(struct cpuidle_device *dev)
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{
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if (!dev->enabled)
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return;
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if (!cpuidle_curr_driver || !cpuidle_curr_governor)
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return;
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dev->enabled = 0;
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if (cpuidle_curr_governor->disable)
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cpuidle_curr_governor->disable(dev);
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cpuidle_remove_state_sysfs(dev);
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enabled_devices--;
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}
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EXPORT_SYMBOL_GPL(cpuidle_disable_device);
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#ifdef CONFIG_ARCH_HAS_CPU_RELAX
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static int poll_idle(struct cpuidle_device *dev, struct cpuidle_state *st)
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{
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ktime_t t1, t2;
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s64 diff;
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int ret;
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t1 = ktime_get();
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local_irq_enable();
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while (!need_resched())
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cpu_relax();
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t2 = ktime_get();
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diff = ktime_to_us(ktime_sub(t2, t1));
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if (diff > INT_MAX)
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diff = INT_MAX;
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ret = (int) diff;
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return ret;
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}
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static void poll_idle_init(struct cpuidle_device *dev)
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{
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struct cpuidle_state *state = &dev->states[0];
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cpuidle_set_statedata(state, NULL);
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snprintf(state->name, CPUIDLE_NAME_LEN, "C0");
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snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
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state->exit_latency = 0;
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state->target_residency = 0;
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state->power_usage = -1;
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state->flags = CPUIDLE_FLAG_POLL;
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state->enter = poll_idle;
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}
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#else
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static void poll_idle_init(struct cpuidle_device *dev) {}
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#endif /* CONFIG_ARCH_HAS_CPU_RELAX */
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/**
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* __cpuidle_register_device - internal register function called before register
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* and enable routines
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* @dev: the cpu
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*
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* cpuidle_lock mutex must be held before this is called
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*/
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static int __cpuidle_register_device(struct cpuidle_device *dev)
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{
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int ret;
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struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu);
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if (!sys_dev)
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return -EINVAL;
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if (!try_module_get(cpuidle_curr_driver->owner))
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return -EINVAL;
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init_completion(&dev->kobj_unregister);
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poll_idle_init(dev);
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per_cpu(cpuidle_devices, dev->cpu) = dev;
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list_add(&dev->device_list, &cpuidle_detected_devices);
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if ((ret = cpuidle_add_sysfs(sys_dev))) {
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module_put(cpuidle_curr_driver->owner);
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return ret;
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}
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dev->registered = 1;
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return 0;
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}
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/**
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* cpuidle_register_device - registers a CPU's idle PM feature
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* @dev: the cpu
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*/
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int cpuidle_register_device(struct cpuidle_device *dev)
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{
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int ret;
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mutex_lock(&cpuidle_lock);
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if ((ret = __cpuidle_register_device(dev))) {
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mutex_unlock(&cpuidle_lock);
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return ret;
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}
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cpuidle_enable_device(dev);
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cpuidle_install_idle_handler();
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mutex_unlock(&cpuidle_lock);
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return 0;
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}
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EXPORT_SYMBOL_GPL(cpuidle_register_device);
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/**
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* cpuidle_unregister_device - unregisters a CPU's idle PM feature
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* @dev: the cpu
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*/
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void cpuidle_unregister_device(struct cpuidle_device *dev)
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{
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struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu);
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if (dev->registered == 0)
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return;
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cpuidle_pause_and_lock();
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cpuidle_disable_device(dev);
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cpuidle_remove_sysfs(sys_dev);
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list_del(&dev->device_list);
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wait_for_completion(&dev->kobj_unregister);
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per_cpu(cpuidle_devices, dev->cpu) = NULL;
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cpuidle_resume_and_unlock();
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module_put(cpuidle_curr_driver->owner);
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}
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EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
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#ifdef CONFIG_SMP
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static void smp_callback(void *v)
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{
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/* we already woke the CPU up, nothing more to do */
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}
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/*
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* This function gets called when a part of the kernel has a new latency
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* requirement. This means we need to get all processors out of their C-state,
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* and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
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* wakes them all right up.
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*/
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static int cpuidle_latency_notify(struct notifier_block *b,
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unsigned long l, void *v)
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{
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smp_call_function(smp_callback, NULL, 1);
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return NOTIFY_OK;
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}
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static struct notifier_block cpuidle_latency_notifier = {
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.notifier_call = cpuidle_latency_notify,
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};
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static inline void latency_notifier_init(struct notifier_block *n)
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{
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pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
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}
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#else /* CONFIG_SMP */
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#define latency_notifier_init(x) do { } while (0)
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#endif /* CONFIG_SMP */
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/**
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* cpuidle_init - core initializer
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*/
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static int __init cpuidle_init(void)
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{
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int ret;
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pm_idle_old = pm_idle;
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ret = cpuidle_add_class_sysfs(&cpu_sysdev_class);
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if (ret)
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return ret;
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latency_notifier_init(&cpuidle_latency_notifier);
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return 0;
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}
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core_initcall(cpuidle_init);
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