13dd52f11a
This patch is a preparation for the multiple cpuidle drivers support. As the next patch will introduce the multiple drivers with the Kconfig option and we want to keep the code clean and understandable, this patch defines a set of functions for encapsulating some common parts and splits what should be done under a lock from the rest. [rjw: Modified the subject and changelog slightly.] Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> Acked-by: Peter De Schrijver <pdeschrijver@nvidia.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
142 lines
2.9 KiB
C
142 lines
2.9 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/cpuidle.h>
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#include "cpuidle.h"
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static struct cpuidle_driver *cpuidle_curr_driver;
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DEFINE_SPINLOCK(cpuidle_driver_lock);
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static void set_power_states(struct cpuidle_driver *drv)
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{
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int i;
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/*
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* cpuidle driver should set the drv->power_specified bit
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* before registering if the driver provides
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* power_usage numbers.
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*
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* If power_specified is not set,
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* we fill in power_usage with decreasing values as the
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* cpuidle code has an implicit assumption that state Cn
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* uses less power than C(n-1).
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*
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* With CONFIG_ARCH_HAS_CPU_RELAX, C0 is already assigned
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* an power value of -1. So we use -2, -3, etc, for other
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* c-states.
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*/
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for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++)
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drv->states[i].power_usage = -1 - i;
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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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drv->refcnt = 0;
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if (!drv->power_specified)
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set_power_states(drv);
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}
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static void cpuidle_set_driver(struct cpuidle_driver *drv)
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{
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cpuidle_curr_driver = drv;
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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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if (!drv || !drv->state_count)
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return -EINVAL;
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if (cpuidle_disabled())
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return -ENODEV;
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if (cpuidle_get_driver())
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return -EBUSY;
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__cpuidle_driver_init(drv);
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cpuidle_set_driver(drv);
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return 0;
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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 (drv != cpuidle_get_driver())
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return;
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if (!WARN_ON(drv->refcnt > 0))
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cpuidle_set_driver(NULL);
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}
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/**
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* cpuidle_register_driver - registers a driver
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* @drv: the driver
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*/
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int cpuidle_register_driver(struct cpuidle_driver *drv)
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{
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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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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_get_driver - return the current driver
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*/
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struct cpuidle_driver *cpuidle_get_driver(void)
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{
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return cpuidle_curr_driver;
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}
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EXPORT_SYMBOL_GPL(cpuidle_get_driver);
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/**
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* cpuidle_unregister_driver - unregisters a driver
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* @drv: the 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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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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}
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EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);
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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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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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void cpuidle_driver_unref(void)
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{
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struct cpuidle_driver *drv = cpuidle_get_driver();
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spin_lock(&cpuidle_driver_lock);
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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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