[linux.git] / drivers / cpuidle / driver.c

/*
 * 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/cpuidle.h>

#include "cpuidle.h"

static struct cpuidle_driver *cpuidle_curr_driver;
DEFINE_SPINLOCK(cpuidle_driver_lock);

static void __cpuidle_register_driver(struct cpuidle_driver *drv)
{
	int i;
	/*
	 * cpuidle driver should set the drv->power_specified bit
	 * before registering if the driver provides
	 * power_usage numbers.
	 *
	 * If power_specified is not set,
	 * we fill in power_usage with decreasing values as the
	 * cpuidle code has an implicit assumption that state Cn
	 * uses less power than C(n-1).
	 *
	 * With CONFIG_ARCH_HAS_CPU_RELAX, C0 is already assigned
	 * an power value of -1.  So we use -2, -3, etc, for other
	 * c-states.
	 */
	if (!drv->power_specified) {
		for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++)
			drv->states[i].power_usage = -1 - i;
	}
}


/**
 * cpuidle_register_driver - registers a driver
 * @drv: the driver
 */
int cpuidle_register_driver(struct cpuidle_driver *drv)
{
	if (!drv || !drv->state_count)
		return -EINVAL;

	if (cpuidle_disabled())
		return -ENODEV;

	spin_lock(&cpuidle_driver_lock);
	if (cpuidle_curr_driver) {
		spin_unlock(&cpuidle_driver_lock);
		return -EBUSY;
	}
	__cpuidle_register_driver(drv);
	cpuidle_curr_driver = drv;
	spin_unlock(&cpuidle_driver_lock);

	return 0;
}

EXPORT_SYMBOL_GPL(cpuidle_register_driver);

/**
 * cpuidle_get_driver - return the current driver
 */
struct cpuidle_driver *cpuidle_get_driver(void)
{
	return cpuidle_curr_driver;
}
EXPORT_SYMBOL_GPL(cpuidle_get_driver);

/**
 * cpuidle_unregister_driver - unregisters a driver
 * @drv: the driver
 */
void cpuidle_unregister_driver(struct cpuidle_driver *drv)
{
	if (drv != cpuidle_curr_driver) {
		WARN(1, "invalid cpuidle_unregister_driver(%s)\n",
			drv->name);
		return;
	}

	spin_lock(&cpuidle_driver_lock);
	cpuidle_curr_driver = NULL;
	spin_unlock(&cpuidle_driver_lock);
}

EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);
Commit	Line	Data
4f86d3a8 LB	1	/*
	2	* driver.c - driver support
	3	*
	4	* (C) 2006-2007 Venkatesh Pallipadi <[email protected]>
	5	* Shaohua Li <[email protected]>
	6	* Adam Belay <[email protected]>
	7	*
	8	* This code is licenced under the GPL.
	9	*/
	10
	11	#include <linux/mutex.h>
	12	#include <linux/module.h>
	13	#include <linux/cpuidle.h>
	14
	15	#include "cpuidle.h"
	16
752138df	17	static struct cpuidle_driver *cpuidle_curr_driver;
4f86d3a8 LB	18	DEFINE_SPINLOCK(cpuidle_driver_lock);
4f86d3a8 LB	19
46bcfad7 DD	20	static void __cpuidle_register_driver(struct cpuidle_driver *drv)
	21	{
	22	int i;
	23	/*
	24	* cpuidle driver should set the drv->power_specified bit
	25	* before registering if the driver provides
	26	* power_usage numbers.
	27	*
	28	* If power_specified is not set,
	29	* we fill in power_usage with decreasing values as the
	30	* cpuidle code has an implicit assumption that state Cn
	31	* uses less power than C(n-1).
	32	*
	33	* With CONFIG_ARCH_HAS_CPU_RELAX, C0 is already assigned
	34	* an power value of -1. So we use -2, -3, etc, for other
	35	* c-states.
	36	*/
	37	if (!drv->power_specified) {
	38	for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++)
	39	drv->states[i].power_usage = -1 - i;
	40	}
	41	}
	42
	43
4f86d3a8 LB	44	/**
	45	* cpuidle_register_driver - registers a driver
	46	* @drv: the driver
	47	*/
	48	int cpuidle_register_driver(struct cpuidle_driver *drv)
	49	{
fc850f39	50	if (!drv \|\| !drv->state_count)
4f86d3a8 LB	51	return -EINVAL;
4f86d3a8 LB	52
62027aea LB	53	if (cpuidle_disabled())
	54	return -ENODEV;
	55
4f86d3a8 LB	56	spin_lock(&cpuidle_driver_lock);
	57	if (cpuidle_curr_driver) {
	58	spin_unlock(&cpuidle_driver_lock);
	59	return -EBUSY;
	60	}
46bcfad7	61	__cpuidle_register_driver(drv);
4f86d3a8 LB	62	cpuidle_curr_driver = drv;
	63	spin_unlock(&cpuidle_driver_lock);
	64
	65	return 0;
	66	}
	67
	68	EXPORT_SYMBOL_GPL(cpuidle_register_driver);
	69
752138df LB	70	/**
	71	* cpuidle_get_driver - return the current driver
	72	*/
	73	struct cpuidle_driver *cpuidle_get_driver(void)
	74	{
	75	return cpuidle_curr_driver;
	76	}
	77	EXPORT_SYMBOL_GPL(cpuidle_get_driver);
	78
4f86d3a8 LB	79	/**
	80	* cpuidle_unregister_driver - unregisters a driver
	81	* @drv: the driver
	82	*/
	83	void cpuidle_unregister_driver(struct cpuidle_driver *drv)
	84	{
c0d64cb0 LB	85	if (drv != cpuidle_curr_driver) {
	86	WARN(1, "invalid cpuidle_unregister_driver(%s)\n",
	87	drv->name);
4f86d3a8	88	return;
c0d64cb0	89	}
4f86d3a8 LB	90
	91	spin_lock(&cpuidle_driver_lock);
	92	cpuidle_curr_driver = NULL;
	93	spin_unlock(&cpuidle_driver_lock);
	94	}
	95
	96	EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);