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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/kernel.h>
- #include <linux/pm_domain.h>
- #include <linux/pm_qos.h>
- #include <linux/hrtimer.h>
- static int dev_update_qos_constraint(struct device *dev, void *data)
- {
- s64 *constraint_ns_p = data;
- s32 constraint_ns = -1;
- if (dev->power.subsys_data && dev->power.subsys_data->domain_data)
- constraint_ns = dev_gpd_data(dev)->td.effective_constraint_ns;
- if (constraint_ns < 0) {
- constraint_ns = dev_pm_qos_read_value(dev);
- constraint_ns *= NSEC_PER_USEC;
- }
- if (constraint_ns == 0)
- return 0;
- /*
- * constraint_ns cannot be negative here, because the device has been
- * suspended.
- */
- if (constraint_ns < *constraint_ns_p || *constraint_ns_p == 0)
- *constraint_ns_p = constraint_ns;
- return 0;
- }
- /**
- * default_stop_ok - Default PM domain governor routine for stopping devices.
- * @dev: Device to check.
- */
- static bool default_stop_ok(struct device *dev)
- {
- struct gpd_timing_data *td = &dev_gpd_data(dev)->td;
- unsigned long flags;
- s64 constraint_ns;
- dev_dbg(dev, "%s()\n", __func__);
- spin_lock_irqsave(&dev->power.lock, flags);
- if (!td->constraint_changed) {
- bool ret = td->cached_stop_ok;
- spin_unlock_irqrestore(&dev->power.lock, flags);
- return ret;
- }
- td->constraint_changed = false;
- td->cached_stop_ok = false;
- td->effective_constraint_ns = -1;
- constraint_ns = __dev_pm_qos_read_value(dev);
- spin_unlock_irqrestore(&dev->power.lock, flags);
- if (constraint_ns < 0)
- return false;
- constraint_ns *= NSEC_PER_USEC;
- /*
- * We can walk the children without any additional locking, because
- * they all have been suspended at this point and their
- * effective_constraint_ns fields won't be modified in parallel with us.
- */
- if (!dev->power.ignore_children)
- device_for_each_child(dev, &constraint_ns,
- dev_update_qos_constraint);
- if (constraint_ns > 0) {
- constraint_ns -= td->suspend_latency_ns +
- td->resume_latency_ns;
- if (constraint_ns == 0)
- return false;
- }
- td->effective_constraint_ns = constraint_ns;
- td->cached_stop_ok = constraint_ns >= 0;
- /*
- * The children have been suspended already, so we don't need to take
- * their stop latencies into account here.
- */
- return td->cached_stop_ok;
- }
- /**
- * 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_off_time_ns;
- s64 off_on_time_ns;
- if (genpd->max_off_time_changed) {
- struct gpd_link *link;
- /*
- * We have to invalidate the cached results for the masters, so
- * use the observation that default_power_down_ok() is not
- * going to be called for any master until this instance
- * returns.
- */
- list_for_each_entry(link, &genpd->slave_links, slave_node)
- link->master->max_off_time_changed = true;
- genpd->max_off_time_changed = false;
- genpd->cached_power_down_ok = false;
- genpd->max_off_time_ns = -1;
- } else {
- return genpd->cached_power_down_ok;
- }
- off_on_time_ns = genpd->power_off_latency_ns +
- genpd->power_on_latency_ns;
- min_off_time_ns = -1;
- /*
- * 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;
- /*
- * 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;
- if (min_off_time_ns > sd_max_off_ns || min_off_time_ns < 0)
- min_off_time_ns = sd_max_off_ns;
- }
- /*
- * Check if the devices in the domain can be off enough time.
- */
- list_for_each_entry(pdd, &genpd->dev_list, list_node) {
- struct gpd_timing_data *td;
- s64 constraint_ns;
- /*
- * Check if the device is allowed to be off long enough for the
- * domain to turn off and on (that's how much time it will
- * have to wait worst case).
- */
- td = &to_gpd_data(pdd)->td;
- constraint_ns = td->effective_constraint_ns;
- /* default_stop_ok() need not be called before us. */
- if (constraint_ns < 0) {
- constraint_ns = dev_pm_qos_read_value(pdd->dev);
- constraint_ns *= NSEC_PER_USEC;
- }
- if (constraint_ns == 0)
- continue;
- /*
- * constraint_ns cannot be negative here, because the device has
- * been suspended.
- */
- if (constraint_ns <= off_on_time_ns)
- return false;
- if (min_off_time_ns > constraint_ns || min_off_time_ns < 0)
- min_off_time_ns = constraint_ns;
- }
- genpd->cached_power_down_ok = true;
- /*
- * If the computed minimum device off time is negative, there are no
- * latency constraints, so the domain can spend arbitrary time in the
- * "off" state.
- */
- if (min_off_time_ns < 0)
- return true;
- /*
- * The difference between the computed minimum subdomain or device off
- * time and the time needed to turn the domain on is the maximum
- * theoretical time this domain can spend in the "off" state.
- */
- genpd->max_off_time_ns = min_off_time_ns - genpd->power_on_latency_ns;
- return true;
- }
- static bool always_on_power_down_ok(struct dev_pm_domain *domain)
- {
- return false;
- }
- struct dev_power_governor simple_qos_governor = {
- .stop_ok = default_stop_ok,
- .power_down_ok = default_power_down_ok,
- };
- /**
- * 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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