linux/drivers/cpuidle/cpuidle.c
Daniel Lezcano 82467a5a88 cpuidle: simplify multiple driver support
Commit bf4d1b5 (cpuidle: support multiple drivers) introduced support
for using multiple cpuidle drivers at the same time.  It added a
couple of new APIs to register the driver per CPU, but that led to
some unnecessary code complexity related to the kernel config options
deciding whether or not the multiple driver support is enabled.  The
code has to work as it did before when the multiple driver support is
not enabled and the multiple driver support has to be compatible with
the previously existing API.

Remove the new API, not used by any driver in the tree yet (but
needed for the HMP cpuidle drivers that will be submitted soon), and
add a new cpumask pointer to the cpuidle driver structure that will
point to the mask of CPUs handled by the given driver.  That will
allow the cpuidle_[un]register_driver() API to be used for the
multiple driver support along with the cpuidle_[un]register()
functions added recently.

[rjw: Changelog]
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-06-11 13:42:38 +02:00

584 lines
13 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/clockchips.h>
#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_PER_CPU(struct cpuidle_device, cpuidle_dev);
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);
/**
* 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 index)
{
int entered_state;
struct cpuidle_state *target_state = &drv->states[index];
ktime_t time_start, time_end;
s64 diff;
time_start = ktime_get();
entered_state = target_state->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;
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_cpu_idle_rcuidle(next_state, dev->cpu);
if (drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP)
clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER,
&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);
if (drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP)
clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT,
&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);
}
#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;
}
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);
/**
* cpuidle_unregister: unregister a driver and the devices. This function
* can be used only if the driver has been previously registered through
* the cpuidle_register function.
*
* @drv: a valid pointer to a struct cpuidle_driver
*/
void cpuidle_unregister(struct cpuidle_driver *drv)
{
int cpu;
struct cpuidle_device *device;
for_each_cpu(cpu, drv->cpumask) {
device = &per_cpu(cpuidle_dev, cpu);
cpuidle_unregister_device(device);
}
cpuidle_unregister_driver(drv);
}
EXPORT_SYMBOL_GPL(cpuidle_unregister);
/**
* cpuidle_register: registers the driver and the cpu devices with the
* coupled_cpus passed as parameter. This function is used for all common
* initialization pattern there are in the arch specific drivers. The
* devices is globally defined in this file.
*
* @drv : a valid pointer to a struct cpuidle_driver
* @coupled_cpus: a cpumask for the coupled states
*
* Returns 0 on success, < 0 otherwise
*/
int cpuidle_register(struct cpuidle_driver *drv,
const struct cpumask *const coupled_cpus)
{
int ret, cpu;
struct cpuidle_device *device;
ret = cpuidle_register_driver(drv);
if (ret) {
pr_err("failed to register cpuidle driver\n");
return ret;
}
for_each_cpu(cpu, drv->cpumask) {
device = &per_cpu(cpuidle_dev, cpu);
device->cpu = cpu;
#ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
/*
* On multiplatform for ARM, the coupled idle states could
* enabled in the kernel even if the cpuidle driver does not
* use it. Note, coupled_cpus is a struct copy.
*/
if (coupled_cpus)
device->coupled_cpus = *coupled_cpus;
#endif
ret = cpuidle_register_device(device);
if (!ret)
continue;
pr_err("Failed to register cpuidle device for cpu%d\n", cpu);
cpuidle_unregister(drv);
break;
}
return ret;
}
EXPORT_SYMBOL_GPL(cpuidle_register);
#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);