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/*
* drivers/base/power/domain_governor.c - Governors for device PM domains.
*
* Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
*
* This file is released under the GPLv2.
*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/pm_domain.h>
#include <linux/pm_qos.h>
#include <linux/hrtimer.h>
/**
* default_stop_ok - Default PM domain governor routine for stopping devices.
* @dev: Device to check.
*/
bool default_stop_ok(struct device *dev)
{
struct gpd_timing_data *td = &dev_gpd_data(dev)->td;
dev_dbg(dev, "%s()\n", __func__);
if (dev->power.max_time_suspended_ns < 0 || td->break_even_ns == 0)
return true;
return td->stop_latency_ns + td->start_latency_ns < td->break_even_ns
&& td->break_even_ns < dev->power.max_time_suspended_ns;
}
/**
* default_power_down_ok - Default generic PM domain power off governor routine.
* @pd: PM domain to check.
*
* This routine must be executed under the PM domain's lock.
*/
static bool default_power_down_ok(struct dev_pm_domain *pd)
{
struct generic_pm_domain *genpd = pd_to_genpd(pd);
struct gpd_link *link;
struct pm_domain_data *pdd;
s64 min_dev_off_time_ns;
s64 off_on_time_ns;
ktime_t time_now = ktime_get();
off_on_time_ns = genpd->power_off_latency_ns +
genpd->power_on_latency_ns;
/*
* It doesn't make sense to remove power from the domain if saving
* the state of all devices in it and the power off/power on operations
* take too much time.
*
* All devices in this domain have been stopped already at this point.
*/
list_for_each_entry(pdd, &genpd->dev_list, list_node) {
if (pdd->dev->driver)
off_on_time_ns +=
to_gpd_data(pdd)->td.save_state_latency_ns;
}
/*
* Check if subdomains can be off for enough time.
*
* All subdomains have been powered off already at this point.
*/
list_for_each_entry(link, &genpd->master_links, master_node) {
struct generic_pm_domain *sd = link->slave;
s64 sd_max_off_ns = sd->max_off_time_ns;
if (sd_max_off_ns < 0)
continue;
sd_max_off_ns -= ktime_to_ns(ktime_sub(time_now,
sd->power_off_time));
/*
* Check if the subdomain is allowed to be off long enough for
* the current domain to turn off and on (that's how much time
* it will have to wait worst case).
*/
if (sd_max_off_ns <= off_on_time_ns)
return false;
}
/*
* Check if the devices in the domain can be off enough time.
*/
min_dev_off_time_ns = -1;
list_for_each_entry(pdd, &genpd->dev_list, list_node) {
struct gpd_timing_data *td;
struct device *dev = pdd->dev;
s64 dev_off_time_ns;
if (!dev->driver || dev->power.max_time_suspended_ns < 0)
continue;
td = &to_gpd_data(pdd)->td;
dev_off_time_ns = dev->power.max_time_suspended_ns -
(td->start_latency_ns + td->restore_state_latency_ns +
ktime_to_ns(ktime_sub(time_now,
dev->power.suspend_time)));
if (dev_off_time_ns <= off_on_time_ns)
return false;
if (min_dev_off_time_ns > dev_off_time_ns
|| min_dev_off_time_ns < 0)
min_dev_off_time_ns = dev_off_time_ns;
}
if (min_dev_off_time_ns < 0) {
/*
* There are no latency constraints, so the domain can spend
* arbitrary time in the "off" state.
*/
genpd->max_off_time_ns = -1;
return true;
}
/*
* The difference between the computed minimum delta and the time needed
* to turn the domain on is the maximum theoretical time this domain can
* spend in the "off" state.
*/
min_dev_off_time_ns -= genpd->power_on_latency_ns;
/*
* If the difference between the computed minimum delta and the time
* needed to turn the domain off and back on on is smaller than the
* domain's power break even time, removing power from the domain is not
* worth it.
*/
if (genpd->break_even_ns >
min_dev_off_time_ns - genpd->power_off_latency_ns)
return false;
genpd->max_off_time_ns = min_dev_off_time_ns;
return true;
}
struct dev_power_governor simple_qos_governor = {
.stop_ok = default_stop_ok,
.power_down_ok = default_power_down_ok,
};
static bool always_on_power_down_ok(struct dev_pm_domain *domain)
{
return false;
}
/**
* pm_genpd_gov_always_on - A governor implementing an always-on policy
*/
struct dev_power_governor pm_domain_always_on_gov = {
.power_down_ok = always_on_power_down_ok,
.stop_ok = default_stop_ok,
};
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