linux/drivers/cpuidle/cpuidle.c

541 lines
12 KiB
C

/*
* 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;
}
static int __cpuidle_register_device(struct cpuidle_device *dev);
static inline int cpuidle_enter(struct cpuidle_device *dev,
struct cpuidle_driver *drv, int index)
{
struct cpuidle_state *target_state = &drv->states[index];
return target_state->enter(dev, drv, index);
}
static inline int cpuidle_enter_tk(struct cpuidle_device *dev,
struct cpuidle_driver *drv, int index)
{
return cpuidle_wrap_enter(dev, drv, index, cpuidle_enter);
}
typedef int (*cpuidle_enter_t)(struct cpuidle_device *dev,
struct cpuidle_driver *drv, int index);
static cpuidle_enter_t cpuidle_enter_ops;
/**
* cpuidle_play_dead - cpu off-lining
*
* Returns in case of an error or no driver
*/
int cpuidle_play_dead(void)
{
struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
int i;
if (!drv)
return -ENODEV;
/* Find lowest-power state that supports long-term idle */
for (i = drv->state_count - 1; i >= CPUIDLE_DRIVER_STATE_START; i--)
if (drv->states[i].enter_dead)
return drv->states[i].enter_dead(dev, i);
return -ENODEV;
}
/**
* cpuidle_enter_state - enter the state and update stats
* @dev: cpuidle device for this cpu
* @drv: cpuidle driver for this cpu
* @next_state: index into drv->states of the state to enter
*/
int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
int next_state)
{
int entered_state;
entered_state = cpuidle_enter_ops(dev, drv, next_state);
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 += dev->last_residency;
dev->states_usage[entered_state].usage++;
} else {
dev->last_residency = 0;
}
return entered_state;
}
/**
* 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;
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;
drv = cpuidle_get_cpu_driver(dev);
/* ask the governor for the next state */
next_state = cpuidle_curr_governor->select(drv, dev);
if (need_resched()) {
dev->last_residency = 0;
/* give the governor an opportunity to reflect on the outcome */
if (cpuidle_curr_governor->reflect)
cpuidle_curr_governor->reflect(dev, next_state);
local_irq_enable();
return 0;
}
trace_power_start_rcuidle(POWER_CSTATE, next_state, dev->cpu);
trace_cpu_idle_rcuidle(next_state, dev->cpu);
if (cpuidle_state_is_coupled(dev, drv, next_state))
entered_state = cpuidle_enter_state_coupled(dev, drv,
next_state);
else
entered_state = cpuidle_enter_state(dev, drv, next_state);
trace_power_end_rcuidle(dev->cpu);
trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
/* 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;
kick_all_cpus_sync();
}
}
/**
* 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);
/* Currently used in suspend/resume path to suspend cpuidle */
void cpuidle_pause(void)
{
mutex_lock(&cpuidle_lock);
cpuidle_uninstall_idle_handler();
mutex_unlock(&cpuidle_lock);
}
/* Currently used in suspend/resume path to resume cpuidle */
void cpuidle_resume(void)
{
mutex_lock(&cpuidle_lock);
cpuidle_install_idle_handler();
mutex_unlock(&cpuidle_lock);
}
/**
* cpuidle_wrap_enter - performs timekeeping and irqen around enter function
* @dev: pointer to a valid cpuidle_device object
* @drv: pointer to a valid cpuidle_driver object
* @index: index of the target cpuidle state.
*/
int cpuidle_wrap_enter(struct cpuidle_device *dev,
struct cpuidle_driver *drv, int index,
int (*enter)(struct cpuidle_device *dev,
struct cpuidle_driver *drv, int index))
{
ktime_t time_start, time_end;
s64 diff;
time_start = ktime_get();
index = enter(dev, drv, index);
time_end = ktime_get();
local_irq_enable();
diff = ktime_to_us(ktime_sub(time_end, time_start));
if (diff > INT_MAX)
diff = INT_MAX;
dev->last_residency = (int) diff;
return index;
}
#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;
state->disabled = false;
}
#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;
struct cpuidle_driver *drv;
if (!dev)
return -EINVAL;
if (dev->enabled)
return 0;
drv = cpuidle_get_cpu_driver(dev);
if (!drv || !cpuidle_curr_governor)
return -EIO;
if (!dev->state_count)
dev->state_count = drv->state_count;
if (dev->registered == 0) {
ret = __cpuidle_register_device(dev);
if (ret)
return ret;
}
cpuidle_enter_ops = drv->en_core_tk_irqen ?
cpuidle_enter_tk : cpuidle_enter;
poll_idle_init(drv);
ret = cpuidle_add_device_sysfs(dev);
if (ret)
return ret;
if (cpuidle_curr_governor->enable &&
(ret = cpuidle_curr_governor->enable(drv, 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_device_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)
{
struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
if (!dev || !dev->enabled)
return;
if (!drv || !cpuidle_curr_governor)
return;
dev->enabled = 0;
if (cpuidle_curr_governor->disable)
cpuidle_curr_governor->disable(drv, dev);
cpuidle_remove_device_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 cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
if (!try_module_get(drv->owner))
return -EINVAL;
per_cpu(cpuidle_devices, dev->cpu) = dev;
list_add(&dev->device_list, &cpuidle_detected_devices);
ret = cpuidle_add_sysfs(dev);
if (ret)
goto err_sysfs;
ret = cpuidle_coupled_register_device(dev);
if (ret)
goto err_coupled;
dev->registered = 1;
return 0;
err_coupled:
cpuidle_remove_sysfs(dev);
err_sysfs:
list_del(&dev->device_list);
per_cpu(cpuidle_devices, dev->cpu) = NULL;
module_put(drv->owner);
return ret;
}
/**
* cpuidle_register_device - registers a CPU's idle PM feature
* @dev: the cpu
*/
int cpuidle_register_device(struct cpuidle_device *dev)
{
int ret;
if (!dev)
return -EINVAL;
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 cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
if (dev->registered == 0)
return;
cpuidle_pause_and_lock();
cpuidle_disable_device(dev);
cpuidle_remove_sysfs(dev);
list_del(&dev->device_list);
per_cpu(cpuidle_devices, dev->cpu) = NULL;
cpuidle_coupled_unregister_device(dev);
cpuidle_resume_and_unlock();
module_put(drv->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);