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Prepare devfreq core framework to support devices which can idle. When device idleness is detected perhaps through runtime-pm, need some mechanism to suspend devfreq load monitoring and resume back when device is online. Present code continues monitoring unless device is removed from devfreq core. This patch introduces following design changes, - use per device work instead of global work to monitor device load. This enables suspend/resume of device devfreq and reduces monitoring code complexity. - decouple delayed work based load monitoring logic from core by introducing helpers functions to be used by governors. This provides flexibility for governors either to use delayed work based monitoring functions or to implement their own mechanism. - devfreq core interacts with governors via events to perform specific actions. These events include start/stop devfreq. This sets ground for adding suspend/resume events. The devfreq apis are not modified and are kept intact. Signed-off-by: Rajagopal Venkat <rajagopal.venkat@linaro.org> Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
143 lines
3.0 KiB
C
143 lines
3.0 KiB
C
/*
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* linux/drivers/devfreq/governor_simpleondemand.c
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*
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* Copyright (C) 2011 Samsung Electronics
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* MyungJoo Ham <myungjoo.ham@samsung.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/slab.h>
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#include <linux/device.h>
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#include <linux/devfreq.h>
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#include <linux/pm.h>
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#include <linux/mutex.h>
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#include "governor.h"
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struct userspace_data {
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unsigned long user_frequency;
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bool valid;
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};
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static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq)
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{
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struct userspace_data *data = df->data;
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if (data->valid) {
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unsigned long adjusted_freq = data->user_frequency;
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if (df->max_freq && adjusted_freq > df->max_freq)
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adjusted_freq = df->max_freq;
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if (df->min_freq && adjusted_freq < df->min_freq)
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adjusted_freq = df->min_freq;
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*freq = adjusted_freq;
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} else {
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*freq = df->previous_freq; /* No user freq specified yet */
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}
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return 0;
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}
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static ssize_t store_freq(struct device *dev, struct device_attribute *attr,
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const char *buf, size_t count)
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{
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struct devfreq *devfreq = to_devfreq(dev);
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struct userspace_data *data;
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unsigned long wanted;
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int err = 0;
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mutex_lock(&devfreq->lock);
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data = devfreq->data;
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sscanf(buf, "%lu", &wanted);
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data->user_frequency = wanted;
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data->valid = true;
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err = update_devfreq(devfreq);
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if (err == 0)
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err = count;
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mutex_unlock(&devfreq->lock);
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return err;
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}
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static ssize_t show_freq(struct device *dev, struct device_attribute *attr,
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char *buf)
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{
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struct devfreq *devfreq = to_devfreq(dev);
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struct userspace_data *data;
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int err = 0;
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mutex_lock(&devfreq->lock);
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data = devfreq->data;
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if (data->valid)
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err = sprintf(buf, "%lu\n", data->user_frequency);
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else
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err = sprintf(buf, "undefined\n");
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mutex_unlock(&devfreq->lock);
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return err;
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}
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static DEVICE_ATTR(set_freq, 0644, show_freq, store_freq);
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static struct attribute *dev_entries[] = {
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&dev_attr_set_freq.attr,
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NULL,
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};
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static struct attribute_group dev_attr_group = {
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.name = "userspace",
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.attrs = dev_entries,
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};
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static int userspace_init(struct devfreq *devfreq)
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{
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int err = 0;
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struct userspace_data *data = kzalloc(sizeof(struct userspace_data),
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GFP_KERNEL);
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if (!data) {
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err = -ENOMEM;
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goto out;
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}
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data->valid = false;
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devfreq->data = data;
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err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);
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out:
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return err;
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}
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static void userspace_exit(struct devfreq *devfreq)
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{
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sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);
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kfree(devfreq->data);
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devfreq->data = NULL;
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}
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static int devfreq_userspace_handler(struct devfreq *devfreq,
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unsigned int event, void *data)
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{
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int ret = 0;
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switch (event) {
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case DEVFREQ_GOV_START:
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ret = userspace_init(devfreq);
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break;
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case DEVFREQ_GOV_STOP:
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userspace_exit(devfreq);
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break;
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default:
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break;
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}
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return ret;
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}
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const struct devfreq_governor devfreq_userspace = {
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.name = "userspace",
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.get_target_freq = devfreq_userspace_func,
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.event_handler = devfreq_userspace_handler,
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};
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