/* * drivers/base/power/domain_governor.c - Governors for device PM domains. * * Copyright (C) 2011 Rafael J. Wysocki , Renesas Electronics Corp. * * This file is released under the GPLv2. */ #include #include #include #include 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->start_latency_ns; if (constraint_ns == 0) return false; } td->effective_constraint_ns = constraint_ns; td->cached_stop_ok = constraint_ns > td->stop_latency_ns || 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; /* * 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; } 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; if (!pdd->dev->driver) continue; /* * 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. */ constraint_ns -= td->restore_state_latency_ns; 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, };