/*
 * driver.c - driver support
 *
 * (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/mutex.h>
#include <linux/module.h>
#include <linux/cpuidle.h>
#include <linux/cpumask.h>
#include <linux/clockchips.h>

#include "cpuidle.h"

DEFINE_SPINLOCK(cpuidle_driver_lock);

static void __cpuidle_set_cpu_driver(struct cpuidle_driver *drv, int cpu);
static struct cpuidle_driver * __cpuidle_get_cpu_driver(int cpu);

static void cpuidle_setup_broadcast_timer(void *arg)
{
        int cpu = smp_processor_id();
        clockevents_notify((long)(arg), &cpu);
}

static void __cpuidle_driver_init(struct cpuidle_driver *drv, int cpu)
{
        int i;

        drv->refcnt = 0;

        for (i = drv->state_count - 1; i >= 0 ; i--) {

                if (!(drv->states[i].flags & CPUIDLE_FLAG_TIMER_STOP))
                        continue;

                drv->bctimer = 1;
                on_each_cpu_mask(get_cpu_mask(cpu), cpuidle_setup_broadcast_timer,
                                 (void *)CLOCK_EVT_NOTIFY_BROADCAST_ON, 1);
                break;
        }
}

static int __cpuidle_register_driver(struct cpuidle_driver *drv, int cpu)
{
        if (!drv || !drv->state_count)
                return -EINVAL;

        if (cpuidle_disabled())
                return -ENODEV;

        if (__cpuidle_get_cpu_driver(cpu))
                return -EBUSY;

        __cpuidle_driver_init(drv, cpu);

        __cpuidle_set_cpu_driver(drv, cpu);

        return 0;
}

static void __cpuidle_unregister_driver(struct cpuidle_driver *drv, int cpu)
{
        if (drv != __cpuidle_get_cpu_driver(cpu))
                return;

        if (!WARN_ON(drv->refcnt > 0))
                __cpuidle_set_cpu_driver(NULL, cpu);

        if (drv->bctimer) {
                drv->bctimer = 0;
                on_each_cpu_mask(get_cpu_mask(cpu), cpuidle_setup_broadcast_timer,
                                 (void *)CLOCK_EVT_NOTIFY_BROADCAST_OFF, 1);
        }
}

#ifdef CONFIG_CPU_IDLE_MULTIPLE_DRIVERS

static DEFINE_PER_CPU(struct cpuidle_driver *, cpuidle_drivers);

static void __cpuidle_set_cpu_driver(struct cpuidle_driver *drv, int cpu)
{
        per_cpu(cpuidle_drivers, cpu) = drv;
}

static struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
{
        return per_cpu(cpuidle_drivers, cpu);
}

static void __cpuidle_unregister_all_cpu_driver(struct cpuidle_driver *drv)
{
        int cpu;
        for_each_present_cpu(cpu)
                __cpuidle_unregister_driver(drv, cpu);
}

static int __cpuidle_register_all_cpu_driver(struct cpuidle_driver *drv)
{
        int ret = 0;
        int i, cpu;

        for_each_present_cpu(cpu) {
                ret = __cpuidle_register_driver(drv, cpu);
                if (ret)
                        break;
        }

        if (ret)
                for_each_present_cpu(i) {
                        if (i == cpu)
                                break;
                        __cpuidle_unregister_driver(drv, i);
                }


        return ret;
}

int cpuidle_register_cpu_driver(struct cpuidle_driver *drv, int cpu)
{
        int ret;

        spin_lock(&cpuidle_driver_lock);
        ret = __cpuidle_register_driver(drv, cpu);
        spin_unlock(&cpuidle_driver_lock);

        return ret;
}

void cpuidle_unregister_cpu_driver(struct cpuidle_driver *drv, int cpu)
{
        spin_lock(&cpuidle_driver_lock);
        __cpuidle_unregister_driver(drv, cpu);
        spin_unlock(&cpuidle_driver_lock);
}

/**
 * cpuidle_register_driver - registers a driver
 * @drv: the driver
 */
int cpuidle_register_driver(struct cpuidle_driver *drv)
{
        int ret;

        spin_lock(&cpuidle_driver_lock);
        ret = __cpuidle_register_all_cpu_driver(drv);
        spin_unlock(&cpuidle_driver_lock);

        return ret;
}
EXPORT_SYMBOL_GPL(cpuidle_register_driver);

/**
 * cpuidle_unregister_driver - unregisters a driver
 * @drv: the driver
 */
void cpuidle_unregister_driver(struct cpuidle_driver *drv)
{
        spin_lock(&cpuidle_driver_lock);
        __cpuidle_unregister_all_cpu_driver(drv);
        spin_unlock(&cpuidle_driver_lock);
}
EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);

#else

static struct cpuidle_driver *cpuidle_curr_driver;

static inline void __cpuidle_set_cpu_driver(struct cpuidle_driver *drv, int cpu)
{
        cpuidle_curr_driver = drv;
}

static inline struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
{
        return cpuidle_curr_driver;
}

/**
 * cpuidle_register_driver - registers a driver
 * @drv: the driver
 */
int cpuidle_register_driver(struct cpuidle_driver *drv)
{
        int ret, cpu;

        cpu = get_cpu();
        spin_lock(&cpuidle_driver_lock);
        ret = __cpuidle_register_driver(drv, cpu);
        spin_unlock(&cpuidle_driver_lock);
        put_cpu();

        return ret;
}
EXPORT_SYMBOL_GPL(cpuidle_register_driver);

/**
 * cpuidle_unregister_driver - unregisters a driver
 * @drv: the driver
 */
void cpuidle_unregister_driver(struct cpuidle_driver *drv)
{
        int cpu;

        cpu = get_cpu();
        spin_lock(&cpuidle_driver_lock);
        __cpuidle_unregister_driver(drv, cpu);
        spin_unlock(&cpuidle_driver_lock);
        put_cpu();
}
EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);
#endif

/**
 * cpuidle_get_driver - return the current driver
 */
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 tied with a cpu
 */
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);

struct cpuidle_driver *cpuidle_driver_ref(void)
{
        struct cpuidle_driver *drv;

        spin_lock(&cpuidle_driver_lock);

        drv = cpuidle_get_driver();
        drv->refcnt++;

        spin_unlock(&cpuidle_driver_lock);
        return drv;
}

void cpuidle_driver_unref(void)
{
        struct cpuidle_driver *drv = cpuidle_get_driver();

        spin_lock(&cpuidle_driver_lock);

        if (drv && !WARN_ON(drv->refcnt <= 0))
                drv->refcnt--;

        spin_unlock(&cpuidle_driver_lock);
}