| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * drivers/base/power/domain_governor.c - Governors for device PM domains. |
| * |
| * Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp. |
| */ |
| #include <linux/kernel.h> |
| #include <linux/pm_domain.h> |
| #include <linux/pm_qos.h> |
| #include <linux/hrtimer.h> |
| #include <linux/cpuidle.h> |
| #include <linux/cpumask.h> |
| #include <linux/ktime.h> |
| |
| static int dev_update_qos_constraint(struct device *dev, void *data) |
| { |
| s64 *constraint_ns_p = data; |
| s64 constraint_ns; |
| |
| if (dev->power.subsys_data && dev->power.subsys_data->domain_data) { |
| struct gpd_timing_data *td = dev_gpd_data(dev)->td; |
| |
| /* |
| * Only take suspend-time QoS constraints of devices into |
| * account, because constraints updated after the device has |
| * been suspended are not guaranteed to be taken into account |
| * anyway. In order for them to take effect, the device has to |
| * be resumed and suspended again. |
| */ |
| constraint_ns = td ? td->effective_constraint_ns : |
| PM_QOS_RESUME_LATENCY_NO_CONSTRAINT_NS; |
| } else { |
| /* |
| * The child is not in a domain and there's no info on its |
| * suspend/resume latencies, so assume them to be negligible and |
| * take its current PM QoS constraint (that's the only thing |
| * known at this point anyway). |
| */ |
| constraint_ns = dev_pm_qos_read_value(dev, DEV_PM_QOS_RESUME_LATENCY); |
| constraint_ns *= NSEC_PER_USEC; |
| } |
| |
| if (constraint_ns < *constraint_ns_p) |
| *constraint_ns_p = constraint_ns; |
| |
| return 0; |
| } |
| |
| /** |
| * default_suspend_ok - Default PM domain governor routine to suspend devices. |
| * @dev: Device to check. |
| */ |
| static bool default_suspend_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_suspend_ok; |
| |
| spin_unlock_irqrestore(&dev->power.lock, flags); |
| return ret; |
| } |
| td->constraint_changed = false; |
| td->cached_suspend_ok = false; |
| td->effective_constraint_ns = 0; |
| constraint_ns = __dev_pm_qos_resume_latency(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 == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT_NS) { |
| /* "No restriction", so the device is allowed to suspend. */ |
| td->effective_constraint_ns = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT_NS; |
| td->cached_suspend_ok = true; |
| } else if (constraint_ns == 0) { |
| /* |
| * This triggers if one of the children that don't belong to a |
| * domain has a zero PM QoS constraint and it's better not to |
| * suspend then. effective_constraint_ns is zero already and |
| * cached_suspend_ok is false, so bail out. |
| */ |
| return false; |
| } else { |
| constraint_ns -= td->suspend_latency_ns + |
| td->resume_latency_ns; |
| /* |
| * effective_constraint_ns is zero already and cached_suspend_ok |
| * is false, so if the computed value is not positive, return |
| * right away. |
| */ |
| if (constraint_ns <= 0) |
| return false; |
| |
| td->effective_constraint_ns = constraint_ns; |
| td->cached_suspend_ok = true; |
| } |
| |
| /* |
| * The children have been suspended already, so we don't need to take |
| * their suspend latencies into account here. |
| */ |
| return td->cached_suspend_ok; |
| } |
| |
| static void update_domain_next_wakeup(struct generic_pm_domain *genpd, ktime_t now) |
| { |
| ktime_t domain_wakeup = KTIME_MAX; |
| ktime_t next_wakeup; |
| struct pm_domain_data *pdd; |
| struct gpd_link *link; |
| |
| if (!(genpd->flags & GENPD_FLAG_MIN_RESIDENCY)) |
| return; |
| |
| /* |
| * Devices that have a predictable wakeup pattern, may specify |
| * their next wakeup. Let's find the next wakeup from all the |
| * devices attached to this domain and from all the sub-domains. |
| * It is possible that component's a next wakeup may have become |
| * stale when we read that here. We will ignore to ensure the domain |
| * is able to enter its optimal idle state. |
| */ |
| list_for_each_entry(pdd, &genpd->dev_list, list_node) { |
| next_wakeup = to_gpd_data(pdd)->td->next_wakeup; |
| if (next_wakeup != KTIME_MAX && !ktime_before(next_wakeup, now)) |
| if (ktime_before(next_wakeup, domain_wakeup)) |
| domain_wakeup = next_wakeup; |
| } |
| |
| list_for_each_entry(link, &genpd->parent_links, parent_node) { |
| struct genpd_governor_data *cgd = link->child->gd; |
| |
| next_wakeup = cgd ? cgd->next_wakeup : KTIME_MAX; |
| if (next_wakeup != KTIME_MAX && !ktime_before(next_wakeup, now)) |
| if (ktime_before(next_wakeup, domain_wakeup)) |
| domain_wakeup = next_wakeup; |
| } |
| |
| genpd->gd->next_wakeup = domain_wakeup; |
| } |
| |
| static bool next_wakeup_allows_state(struct generic_pm_domain *genpd, |
| unsigned int state, ktime_t now) |
| { |
| ktime_t domain_wakeup = genpd->gd->next_wakeup; |
| s64 idle_time_ns, min_sleep_ns; |
| |
| min_sleep_ns = genpd->states[state].power_off_latency_ns + |
| genpd->states[state].residency_ns; |
| |
| idle_time_ns = ktime_to_ns(ktime_sub(domain_wakeup, now)); |
| |
| return idle_time_ns >= min_sleep_ns; |
| } |
| |
| static bool __default_power_down_ok(struct dev_pm_domain *pd, |
| unsigned int state) |
| { |
| 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; |
| |
| off_on_time_ns = genpd->states[state].power_off_latency_ns + |
| genpd->states[state].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->parent_links, parent_node) { |
| struct genpd_governor_data *cgd = link->child->gd; |
| |
| s64 sd_max_off_ns = cgd ? cgd->max_off_time_ns : -1; |
| |
| 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; |
| /* |
| * Zero means "no suspend at all" and this runs only when all |
| * devices in the domain are suspended, so it must be positive. |
| */ |
| if (constraint_ns == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT_NS) |
| continue; |
| |
| 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; |
| } |
| |
| /* |
| * 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->gd->max_off_time_ns = min_off_time_ns - |
| genpd->states[state].power_on_latency_ns; |
| return true; |
| } |
| |
| /** |
| * _default_power_down_ok - Default generic PM domain power off governor routine. |
| * @pd: PM domain to check. |
| * @now: current ktime. |
| * |
| * This routine must be executed under the PM domain's lock. |
| */ |
| static bool _default_power_down_ok(struct dev_pm_domain *pd, ktime_t now) |
| { |
| struct generic_pm_domain *genpd = pd_to_genpd(pd); |
| struct genpd_governor_data *gd = genpd->gd; |
| int state_idx = genpd->state_count - 1; |
| struct gpd_link *link; |
| |
| /* |
| * Find the next wakeup from devices that can determine their own wakeup |
| * to find when the domain would wakeup and do it for every device down |
| * the hierarchy. It is not worth while to sleep if the state's residency |
| * cannot be met. |
| */ |
| update_domain_next_wakeup(genpd, now); |
| if ((genpd->flags & GENPD_FLAG_MIN_RESIDENCY) && (gd->next_wakeup != KTIME_MAX)) { |
| /* Let's find out the deepest domain idle state, the devices prefer */ |
| while (state_idx >= 0) { |
| if (next_wakeup_allows_state(genpd, state_idx, now)) { |
| gd->max_off_time_changed = true; |
| break; |
| } |
| state_idx--; |
| } |
| |
| if (state_idx < 0) { |
| state_idx = 0; |
| gd->cached_power_down_ok = false; |
| goto done; |
| } |
| } |
| |
| if (!gd->max_off_time_changed) { |
| genpd->state_idx = gd->cached_power_down_state_idx; |
| return gd->cached_power_down_ok; |
| } |
| |
| /* |
| * We have to invalidate the cached results for the parents, so |
| * use the observation that default_power_down_ok() is not |
| * going to be called for any parent until this instance |
| * returns. |
| */ |
| list_for_each_entry(link, &genpd->child_links, child_node) { |
| struct genpd_governor_data *pgd = link->parent->gd; |
| |
| if (pgd) |
| pgd->max_off_time_changed = true; |
| } |
| |
| gd->max_off_time_ns = -1; |
| gd->max_off_time_changed = false; |
| gd->cached_power_down_ok = true; |
| |
| /* |
| * Find a state to power down to, starting from the state |
| * determined by the next wakeup. |
| */ |
| while (!__default_power_down_ok(pd, state_idx)) { |
| if (state_idx == 0) { |
| gd->cached_power_down_ok = false; |
| break; |
| } |
| state_idx--; |
| } |
| |
| done: |
| genpd->state_idx = state_idx; |
| gd->cached_power_down_state_idx = genpd->state_idx; |
| return gd->cached_power_down_ok; |
| } |
| |
| static bool default_power_down_ok(struct dev_pm_domain *pd) |
| { |
| return _default_power_down_ok(pd, ktime_get()); |
| } |
| |
| #ifdef CONFIG_CPU_IDLE |
| static bool cpu_power_down_ok(struct dev_pm_domain *pd) |
| { |
| struct generic_pm_domain *genpd = pd_to_genpd(pd); |
| struct cpuidle_device *dev; |
| ktime_t domain_wakeup, next_hrtimer; |
| ktime_t now = ktime_get(); |
| s64 idle_duration_ns; |
| int cpu, i; |
| |
| /* Validate dev PM QoS constraints. */ |
| if (!_default_power_down_ok(pd, now)) |
| return false; |
| |
| if (!(genpd->flags & GENPD_FLAG_CPU_DOMAIN)) |
| return true; |
| |
| /* |
| * Find the next wakeup for any of the online CPUs within the PM domain |
| * and its subdomains. Note, we only need the genpd->cpus, as it already |
| * contains a mask of all CPUs from subdomains. |
| */ |
| domain_wakeup = ktime_set(KTIME_SEC_MAX, 0); |
| for_each_cpu_and(cpu, genpd->cpus, cpu_online_mask) { |
| dev = per_cpu(cpuidle_devices, cpu); |
| if (dev) { |
| next_hrtimer = READ_ONCE(dev->next_hrtimer); |
| if (ktime_before(next_hrtimer, domain_wakeup)) |
| domain_wakeup = next_hrtimer; |
| } |
| } |
| |
| /* The minimum idle duration is from now - until the next wakeup. */ |
| idle_duration_ns = ktime_to_ns(ktime_sub(domain_wakeup, now)); |
| if (idle_duration_ns <= 0) |
| return false; |
| |
| /* |
| * Find the deepest idle state that has its residency value satisfied |
| * and by also taking into account the power off latency for the state. |
| * Start at the state picked by the dev PM QoS constraint validation. |
| */ |
| i = genpd->state_idx; |
| do { |
| if (idle_duration_ns >= (genpd->states[i].residency_ns + |
| genpd->states[i].power_off_latency_ns)) { |
| genpd->state_idx = i; |
| return true; |
| } |
| } while (--i >= 0); |
| |
| return false; |
| } |
| |
| struct dev_power_governor pm_domain_cpu_gov = { |
| .suspend_ok = default_suspend_ok, |
| .power_down_ok = cpu_power_down_ok, |
| }; |
| #endif |
| |
| struct dev_power_governor simple_qos_governor = { |
| .suspend_ok = default_suspend_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 = { |
| .suspend_ok = default_suspend_ok, |
| }; |