/*
* 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_params.h>
#include <linux/cpu.h>
#include <linux/cpuidle.h>
#include <linux/ktime.h>
#include <linux/hrtimer.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 void (*pm_idle_old)(void);
static int enabled_devices;
#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
*/
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
#if defined(CONFIG_ARCH_HAS_DEFAULT_IDLE)
default_idle();
#else
local_irq_enable();
#endif
return;
}
#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
/*
* Call the device's prepare function before calling the
* governor's select function. ->prepare gives the device's
* cpuidle driver a chance to update any dynamic information
* of its cpuidle states for the current idle period, e.g.
* state availability, latencies, residencies, etc.
*/
if (dev->prepare)
dev->prepare(dev);
/* ask the governor for the next state */
next_state = cpuidle_curr_governor->select(dev);
if (need_resched()) {
local_irq_enable();
return;
}
target_state = &dev->states[next_state];
/* enter the state and update stats */
dev->last_state = target_state;
dev->last_residency = target_state->enter(dev, target_state);
if (dev->last_state)
target_state = dev->last_state;
target_state->time += (unsigned long long)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);
trace_power_end(smp_processor_id());
}
/**
* 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_old && (pm_idle != pm_idle_old)) {
pm_idle = pm_idle_old;
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);
/**
* 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;
}
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_get_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);
#ifdef CONFIG_ARCH_HAS_CPU_RELAX
static int poll_idle(struct cpuidle_device *dev, struct cpuidle_state *st)
{
ktime_t t1, t2;
s64 diff;
int ret;
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;
ret = (int) diff;
return ret;
}
static void poll_idle_init(struct cpuidle_device *dev)
{
struct cpuidle_state *state = &dev->states[0];
cpuidle_set_statedata(state, NULL);
snprintf(state->name, CPUIDLE_NAME_LEN, "C0");
snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
state->exit_latency = 0;
state->target_residency = 0;
state->power_usage = -1;
state->flags = CPUIDLE_FLAG_POLL;
state->enter = poll_idle;
}
#else
static void poll_idle_init(struct cpuidle_device *dev) {}
#endif /* CONFIG_ARCH_HAS_CPU_RELAX */
/**
* __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 sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu);
struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();
if (!sys_dev)
return -EINVAL;
if (!try_module_get(cpuidle_driver->owner))
return -EINVAL;
init_completion(&dev->kobj_unregister);
poll_idle_init(dev);
/*
* cpuidle driver should set the dev->power_specified bit
* before registering the device if the driver provides
* power_usage numbers.
*
* For those devices whose ->power_specified is not set,
* we fill in power_usage with decreasing values as the
* cpuidle code has an implicit assumption that state Cn
* uses less power than C(n-1).
*
* With CONFIG_ARCH_HAS_CPU_RELAX, C0 is already assigned
* an power value of -1. So we use -2, -3, etc, for other
* c-states.
*/
if (!dev->power_specified) {
int i;
for (i = CPUIDLE_DRIVER_STATE_START; i < dev->state_count; i++)
dev->states[i].power_usage = -1 - i;
}
per_cpu(cpuidle_devices, dev->cpu) = dev;
list_add(&dev->device_list, &cpuidle_detected_devices);
if ((ret = cpuidle_add_sysfs(sys_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 sys_device *sys_dev = get_cpu_sysdev((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(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_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;
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);
