diff options
Diffstat (limited to 'drivers/pmdomain/governor.c')
| -rw-r--r-- | drivers/pmdomain/governor.c | 418 |
1 files changed, 418 insertions, 0 deletions
diff --git a/drivers/pmdomain/governor.c b/drivers/pmdomain/governor.c new file mode 100644 index 0000000000..d1a10eeebd --- /dev/null +++ b/drivers/pmdomain/governor.c @@ -0,0 +1,418 @@ +// 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. + * + * Returns: true if OK to suspend, false if not OK to suspend + */ +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. + * + * Returns: true if OK to power down, false if not OK to power down + */ +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; + + /* Store the next domain_wakeup to allow consumers to use it. */ + genpd->gd->next_hrtimer = domain_wakeup; + + /* + * 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_domain_always_on_gov - A governor implementing an always-on policy + */ +struct dev_power_governor pm_domain_always_on_gov = { + .suspend_ok = default_suspend_ok, +}; |