governor_userspace.c

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/*
 *  linux/drivers/devfreq/governor_simpleondemand.c
 *
 *  Copyright (C) 2011 Samsung Electronics
 *  MyungJoo Ham <[email protected]>
 *
 * 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.
 */

#include <linux/slab.h>
#include <linux/device.h>
#include <linux/devfreq.h>
#include <linux/pm.h>
#include <linux/mutex.h>
#include "governor.h"

struct userspace_data {
    unsigned long user_frequency;
    bool valid;
};

static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq)
{
    struct userspace_data *data = df->data;

    if (data->valid) {
        unsigned long adjusted_freq = data->user_frequency;

        if (df->max_freq && adjusted_freq > df->max_freq)
            adjusted_freq = df->max_freq;

        if (df->min_freq && adjusted_freq < df->min_freq)
            adjusted_freq = df->min_freq;

        *freq = adjusted_freq;
    } else {
        *freq = df->previous_freq; /* No user freq specified yet */
    }
    return 0;
}

static ssize_t store_freq(struct device *dev, struct device_attribute *attr,
              const char *buf, size_t count)
{
    struct devfreq *devfreq = to_devfreq(dev);
    struct userspace_data *data;
    unsigned long wanted;
    int err = 0;


    mutex_lock(&devfreq->lock);
    data = devfreq->data;

    sscanf(buf, "%lu", &wanted);
    data->user_frequency = wanted;
    data->valid = true;
    err = update_devfreq(devfreq);
    if (err == 0)
        err = count;
    mutex_unlock(&devfreq->lock);
    return err;
}

static ssize_t show_freq(struct device *dev, struct device_attribute *attr,
             char *buf)
{
    struct devfreq *devfreq = to_devfreq(dev);
    struct userspace_data *data;
    int err = 0;

    mutex_lock(&devfreq->lock);
    data = devfreq->data;

    if (data->valid)
        err = sprintf(buf, "%lu\n", data->user_frequency);
    else
        err = sprintf(buf, "undefined\n");
    mutex_unlock(&devfreq->lock);
    return err;
}

static DEVICE_ATTR(set_freq, 0644, show_freq, store_freq);
static struct attribute *dev_entries[] = {
    &dev_attr_set_freq.attr,
    NULL,
};
static struct attribute_group dev_attr_group = {
    .name   = "userspace",
    .attrs  = dev_entries,
};

static int userspace_init(struct devfreq *devfreq)
{
    int err = 0;
    struct userspace_data *data = kzalloc(sizeof(struct userspace_data),
                          GFP_KERNEL);

    if (!data) {
        err = -ENOMEM;
        goto out;
    }
    data->valid = false;
    devfreq->data = data;

    err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);
out:
    return err;
}

static void userspace_exit(struct devfreq *devfreq)
{
    sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);
    kfree(devfreq->data);
    devfreq->data = NULL;
}

const struct devfreq_governor devfreq_userspace = {
    .name = "userspace",
    .get_target_freq = devfreq_userspace_func,
    .init = userspace_init,
    .exit = userspace_exit,
    .no_central_polling = true,
};