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