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https://github.com/followmsi/android_kernel_google_msm.git
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7e6fdd4bad
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>
118 lines
2.9 KiB
C
118 lines
2.9 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/errno.h>
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#include <linux/devfreq.h>
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#include <linux/math64.h>
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#include "governor.h"
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/* Default constants for DevFreq-Simple-Ondemand (DFSO) */
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#define DFSO_UPTHRESHOLD (90)
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#define DFSO_DOWNDIFFERENCTIAL (5)
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static int devfreq_simple_ondemand_func(struct devfreq *df,
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unsigned long *freq)
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{
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struct devfreq_dev_status stat;
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int err = df->profile->get_dev_status(df->dev.parent, &stat);
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unsigned long long a, b;
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unsigned int dfso_upthreshold = DFSO_UPTHRESHOLD;
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unsigned int dfso_downdifferential = DFSO_DOWNDIFFERENCTIAL;
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struct devfreq_simple_ondemand_data *data = df->data;
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unsigned long max = (df->max_freq) ? df->max_freq : UINT_MAX;
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if (err)
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return err;
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if (data) {
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if (data->upthreshold)
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dfso_upthreshold = data->upthreshold;
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if (data->downdifferential)
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dfso_downdifferential = data->downdifferential;
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}
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if (dfso_upthreshold > 100 ||
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dfso_upthreshold < dfso_downdifferential)
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return -EINVAL;
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/* Assume MAX if it is going to be divided by zero */
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if (stat.total_time == 0) {
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*freq = max;
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return 0;
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}
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/* Prevent overflow */
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if (stat.busy_time >= (1 << 24) || stat.total_time >= (1 << 24)) {
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stat.busy_time >>= 7;
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stat.total_time >>= 7;
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}
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/* Set MAX if it's busy enough */
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if (stat.busy_time * 100 >
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stat.total_time * dfso_upthreshold) {
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*freq = max;
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return 0;
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}
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/* Set MAX if we do not know the initial frequency */
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if (stat.current_frequency == 0) {
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*freq = max;
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return 0;
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}
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/* Keep the current frequency */
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if (stat.busy_time * 100 >
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stat.total_time * (dfso_upthreshold - dfso_downdifferential)) {
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*freq = stat.current_frequency;
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return 0;
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}
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/* Set the desired frequency based on the load */
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a = stat.busy_time;
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a *= stat.current_frequency;
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b = div_u64(a, stat.total_time);
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b *= 100;
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b = div_u64(b, (dfso_upthreshold - dfso_downdifferential / 2));
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*freq = (unsigned long) b;
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if (df->min_freq && *freq < df->min_freq)
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*freq = df->min_freq;
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if (df->max_freq && *freq > df->max_freq)
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*freq = df->max_freq;
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return 0;
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}
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static int devfreq_simple_ondemand_handler(struct devfreq *devfreq,
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unsigned int event, void *data)
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{
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switch (event) {
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case DEVFREQ_GOV_START:
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devfreq_monitor_start(devfreq);
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break;
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case DEVFREQ_GOV_STOP:
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devfreq_monitor_stop(devfreq);
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break;
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case DEVFREQ_GOV_INTERVAL:
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devfreq_interval_update(devfreq, (unsigned int *)data);
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break;
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default:
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break;
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}
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return 0;
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}
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const struct devfreq_governor devfreq_simple_ondemand = {
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.name = "simple_ondemand",
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.get_target_freq = devfreq_simple_ondemand_func,
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.event_handler = devfreq_simple_ondemand_handler,
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};
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