diff options
Diffstat (limited to 'kernel/drivers/base/power/domain_governor.c')
-rw-r--r-- | kernel/drivers/base/power/domain_governor.c | 239 |
1 files changed, 239 insertions, 0 deletions
diff --git a/kernel/drivers/base/power/domain_governor.c b/kernel/drivers/base/power/domain_governor.c new file mode 100644 index 000000000..2a4154a09 --- /dev/null +++ b/kernel/drivers/base/power/domain_governor.c @@ -0,0 +1,239 @@ +/* + * 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->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, +}; |