/*
* driver.c - driver support
*
* (C) 2006-2007 Venkatesh Pallipadi <[email protected]>
* Shaohua Li <[email protected]>
* Adam Belay <[email protected]>
*
* This code is licenced under the GPL.
*/
#include <linux/mutex.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/sched/idle.h>
#include <linux/cpuidle.h>
#include <linux/cpumask.h>
#include <linux/tick.h>
#include <linux/cpu.h>
#include <linux/math64.h>
#include "cpuidle.h"
DEFINE_SPINLOCK(cpuidle_driver_lock);
#ifdef CONFIG_CPU_IDLE_MULTIPLE_DRIVERS
static DEFINE_PER_CPU(struct cpuidle_driver *, cpuidle_drivers);
/**
* __cpuidle_get_cpu_driver - return the cpuidle driver tied to a CPU.
* @cpu: the CPU handled by the driver
*
* Returns a pointer to struct cpuidle_driver or NULL if no driver has been
* registered for @cpu.
*/
static struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
{
return per_cpu(cpuidle_drivers, cpu);
}
/**
* __cpuidle_unset_driver - unset per CPU driver variables.
* @drv: a valid pointer to a struct cpuidle_driver
*
* For each CPU in the driver's CPU mask, unset the registered driver per CPU
* variable. If @drv is different from the registered driver, the corresponding
* variable is not cleared.
*/
static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv)
{
int cpu;
for_each_cpu(cpu, drv->cpumask) {
if (drv != __cpuidle_get_cpu_driver(cpu))
continue;
per_cpu(cpuidle_drivers, cpu) = NULL;
}
}
/**
* __cpuidle_set_driver - set per CPU driver variables for the given driver.
* @drv: a valid pointer to a struct cpuidle_driver
*
* Returns 0 on success, -EBUSY if any CPU in the cpumask have a driver
* different from drv already.
*/
static inline int __cpuidle_set_driver(struct cpuidle_driver *drv)
{
int cpu;
for_each_cpu(cpu, drv->cpumask) {
struct cpuidle_driver *old_drv;
old_drv = __cpuidle_get_cpu_driver(cpu);
if (old_drv && old_drv != drv)
return -EBUSY;
}
for_each_cpu(cpu, drv->cpumask)
per_cpu(cpuidle_drivers, cpu) = drv;
return 0;
}
#else
static struct cpuidle_driver *cpuidle_curr_driver;
/**
* __cpuidle_get_cpu_driver - return the global cpuidle driver pointer.
* @cpu: ignored without the multiple driver support
*
* Return a pointer to a struct cpuidle_driver object or NULL if no driver was
* previously registered.
*/
static inline struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
{
return cpuidle_curr_driver;
}
/**
* __cpuidle_set_driver - assign the global cpuidle driver variable.
* @drv: pointer to a struct cpuidle_driver object
*
* Returns 0 on success, -EBUSY if the driver is already registered.
*/
static inline int __cpuidle_set_driver(struct cpuidle_driver *drv)
{
if (cpuidle_curr_driver)
return -EBUSY;
cpuidle_curr_driver = drv;
return 0;
}
/**
* __cpuidle_unset_driver - unset the global cpuidle driver variable.
* @drv: a pointer to a struct cpuidle_driver
*
* Reset the global cpuidle variable to NULL. If @drv does not match the
* registered driver, do nothing.
*/
static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv)
{
if (drv == cpuidle_curr_driver)
cpuidle_curr_driver = NULL;
}
#endif
/**
* cpuidle_setup_broadcast_timer - enable/disable the broadcast timer on a cpu
* @arg: a void pointer used to match the SMP cross call API
*
* If @arg is NULL broadcast is disabled otherwise enabled
*
* This function is executed per CPU by an SMP cross call. It's not
* supposed to be called directly.
*/
static void cpuidle_setup_broadcast_timer(void *arg)
{
if (arg)
tick_broadcast_enable();
else
tick_broadcast_disable();
}
/**
* __cpuidle_driver_init - initialize the driver's internal data
* @drv: a valid pointer to a struct cpuidle_driver
*/
static void __cpuidle_driver_init(struct cpuidle_driver *drv)
{
int i;
/*
* Use all possible CPUs as the default, because if the kernel boots
* with some CPUs offline and then we online one of them, the CPU
* notifier has to know which driver to assign.
*/
if (!drv->cpumask)
drv->cpumask = (struct cpumask *)cpu_possible_mask;
for (i = 0; i < drv->state_count; i++) {
struct cpuidle_state *s = &drv->states[i];
/*
* Look for the timer stop flag in the different states and if
* it is found, indicate that the broadcast timer has to be set
* up.
*/
if (s->flags & CPUIDLE_FLAG_TIMER_STOP)
drv->bctimer = 1;
/*
* The core will use the target residency and exit latency
* values in nanoseconds, but allow drivers to provide them in
* microseconds too.
*/
if (s->target_residency > 0)
s->target_residency_ns = s->target_residency * NSEC_PER_USEC;
else if (s->target_residency_ns < 0)
s->target_residency_ns = 0;
else
s->target_residency = div_u64(s->target_residency_ns, NSEC_PER_USEC);
if (s->exit_latency > 0)
s->exit_latency_ns = mul_u32_u32(s->exit_latency, NSEC_PER_USEC);
else if (s->exit_latency_ns < 0)
s->exit_latency_ns = 0;
else
s->exit_latency = div_u64(s->exit_latency_ns, NSEC_PER_USEC);
}
}
/**
* __cpuidle_register_driver: register the driver
* @drv: a valid pointer to a struct cpuidle_driver
*
* Do some sanity checks, initialize the driver, assign the driver to the
* global cpuidle driver variable(s) and set up the broadcast timer if the
* cpuidle driver has some states that shut down the local timer.
*
* Returns 0 on success, a negative error code otherwise:
* * -EINVAL if the driver pointer is NULL or no idle states are available
* * -ENODEV if the cpuidle framework is disabled
* * -EBUSY if the driver is already assigned to the global variable(s)
*/
static int __cpuidle_register_driver(struct cpuidle_driver *drv)
{
int ret;
if (!drv || !drv->state_count)
return -EINVAL;
ret = cpuidle_coupled_state_verify(drv);
if (ret)
return ret;
if (cpuidle_disabled())
return -ENODEV;
__cpuidle_driver_init(drv);
ret = __cpuidle_set_driver(drv);
if (ret)
return ret;
if (drv->bctimer)
on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer,
(void *)1, 1);
return 0;
}
/**
* __cpuidle_unregister_driver - unregister the driver
* @drv: a valid pointer to a struct cpuidle_driver
*
* Check if the driver is no longer in use, reset the global cpuidle driver
* variable(s) and disable the timer broadcast notification mechanism if it was
* in use.
*
*/
static void __cpuidle_unregister_driver(struct cpuidle_driver *drv)
{
if (drv->bctimer) {
drv->bctimer = 0;
on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer,
NULL, 1);
}
__cpuidle_unset_driver(drv);
}
/**
* cpuidle_register_driver - registers a driver
* @drv: a pointer to a valid struct cpuidle_driver
*
* Register the driver under a lock to prevent concurrent attempts to
* [un]register the driver from occuring at the same time.
*
* Returns 0 on success, a negative error code (returned by
* __cpuidle_register_driver()) otherwise.
*/
int cpuidle_register_driver(struct cpuidle_driver *drv)
{
struct cpuidle_governor *gov;
int ret;
spin_lock(&cpuidle_driver_lock);
ret = __cpuidle_register_driver(drv);
spin_unlock(&cpuidle_driver_lock);
if (!ret && !strlen(param_governor) && drv->governor &&
(cpuidle_get_driver() == drv)) {
mutex_lock(&cpuidle_lock);
gov = cpuidle_find_governor(drv->governor);
if (gov) {
cpuidle_prev_governor = cpuidle_curr_governor;
if (cpuidle_switch_governor(gov) < 0)
cpuidle_prev_governor = NULL;
}
mutex_unlock(&cpuidle_lock);
}
return ret;
}
EXPORT_SYMBOL_GPL(cpuidle_register_driver);
/**
* cpuidle_unregister_driver - unregisters a driver
* @drv: a pointer to a valid struct cpuidle_driver
*
* Unregisters the cpuidle driver under a lock to prevent concurrent attempts
* to [un]register the driver from occuring at the same time. @drv has to
* match the currently registered driver.
*/
void cpuidle_unregister_driver(struct cpuidle_driver *drv)
{
bool enabled = (cpuidle_get_driver() == drv);
spin_lock(&cpuidle_driver_lock);
__cpuidle_unregister_driver(drv);
spin_unlock(&cpuidle_driver_lock);
if (!enabled)
return;
mutex_lock(&cpuidle_lock);
if (cpuidle_prev_governor) {
if (!cpuidle_switch_governor(cpuidle_prev_governor))
cpuidle_prev_governor = NULL;
}
mutex_unlock(&cpuidle_lock);
}
EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);
/**
* cpuidle_get_driver - return the driver tied to the current CPU.
*
* Returns a struct cpuidle_driver pointer, or NULL if no driver is registered.
*/
struct cpuidle_driver *cpuidle_get_driver(void)
{
struct cpuidle_driver *drv;
int cpu;
cpu = get_cpu();
drv = __cpuidle_get_cpu_driver(cpu);
put_cpu();
return drv;
}
EXPORT_SYMBOL_GPL(cpuidle_get_driver);
/**
* cpuidle_get_cpu_driver - return the driver registered for a CPU.
* @dev: a valid pointer to a struct cpuidle_device
*
* Returns a struct cpuidle_driver pointer, or NULL if no driver is registered
* for the CPU associated with @dev.
*/
struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev)
{
if (!dev)
return NULL;
return __cpuidle_get_cpu_driver(dev->cpu);
}
EXPORT_SYMBOL_GPL(cpuidle_get_cpu_driver);
/**
* cpuidle_driver_state_disabled - Disable or enable an idle state
* @drv: cpuidle driver owning the state
* @idx: State index
* @disable: Whether or not to disable the state
*/
void cpuidle_driver_state_disabled(struct cpuidle_driver *drv, int idx,
bool disable)
{
unsigned int cpu;
mutex_lock(&cpuidle_lock);
spin_lock(&cpuidle_driver_lock);
if (!drv->cpumask) {
drv->states[idx].flags |= CPUIDLE_FLAG_UNUSABLE;
goto unlock;
}
for_each_cpu(cpu, drv->cpumask) {
struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
if (!dev)
continue;
if (disable)
dev->states_usage[idx].disable |= CPUIDLE_STATE_DISABLED_BY_DRIVER;
else
dev->states_usage[idx].disable &= ~CPUIDLE_STATE_DISABLED_BY_DRIVER;
}
unlock:
spin_unlock(&cpuidle_driver_lock);
mutex_unlock(&cpuidle_lock);
}
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