linux-imx

/*

 * devfreq-event: a framework to provide raw data and events of devfreq devices

 *

 * Copyright (C) 2015 Samsung Electronics

 * Author: Chanwoo Choi <cw00.choi@samsung.com>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 * This driver is based on drivers/devfreq/devfreq.c.

 */

​

#include <linux/devfreq-event.h>

#include <linux/kernel.h>

#include <linux/err.h>

#include <linux/init.h>

#include <linux/export.h>

#include <linux/slab.h>

#include <linux/list.h>

#include <linux/of.h>

​

static struct class *devfreq_event_class;

​

/* The list of all devfreq event list */

static LIST_HEAD(devfreq_event_list);

static DEFINE_MUTEX(devfreq_event_list_lock);

​

#define to_devfreq_event(DEV) container_of(DEV, struct devfreq_event_dev, dev)

​

/**

 * devfreq_event_enable_edev() - Enable the devfreq-event dev and increase

 *               the enable_count of devfreq-event dev.

 * @edev    : the devfreq-event device

 *

 * Note that this function increase the enable_count and enable the

 * devfreq-event device. The devfreq-event device should be enabled before

 * using it by devfreq device.

 */

int devfreq_event_enable_edev(struct devfreq_event_dev *edev)

{

    int ret = 0;

​

    if (!edev || !edev->desc)

        return -EINVAL;

​

    mutex_lock(&edev->lock);

    if (edev->desc->ops && edev->desc->ops->enable

            && edev->enable_count == 0) {

        ret = edev->desc->ops->enable(edev);

        if (ret < 0)

            goto err;

    }

    edev->enable_count++;

err:

    mutex_unlock(&edev->lock);

​

    return ret;

}

EXPORT_SYMBOL_GPL(devfreq_event_enable_edev);

​

/**

 * devfreq_event_disable_edev() - Disable the devfreq-event dev and decrease

 *                the enable_count of the devfreq-event dev.

 * @edev    : the devfreq-event device

 *

 * Note that this function decrease the enable_count and disable the

 * devfreq-event device. After the devfreq-event device is disabled,

 * devfreq device can't use the devfreq-event device for get/set/reset

 * operations.

 */

int devfreq_event_disable_edev(struct devfreq_event_dev *edev)

{

    int ret = 0;

​

    if (!edev || !edev->desc)

        return -EINVAL;

​

    mutex_lock(&edev->lock);

    if (edev->enable_count <= 0) {

        dev_warn(&edev->dev, "unbalanced enable_count\n");

        ret = -EIO;

        goto err;

    }

​

    if (edev->desc->ops && edev->desc->ops->disable

            && edev->enable_count == 1) {

        ret = edev->desc->ops->disable(edev);

        if (ret < 0)

            goto err;

    }

    edev->enable_count--;