diff options
Diffstat (limited to 'drivers/base/power/domain_governor.c')
| -rw-r--r-- | drivers/base/power/domain_governor.c | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/drivers/base/power/domain_governor.c b/drivers/base/power/domain_governor.c new file mode 100644 index 00000000000..66a265bf586 --- /dev/null +++ b/drivers/base/power/domain_governor.c @@ -0,0 +1,170 @@ +/* + * 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/init.h> +#include <linux/kernel.h> +#include <linux/pm_domain.h> +#include <linux/pm_qos.h> +#include <linux/hrtimer.h> + +#ifdef CONFIG_PM_RUNTIME + +/** + * default_stop_ok - Default PM domain governor routine for stopping devices. + * @dev: Device to check. + */ +bool default_stop_ok(struct device *dev) +{ + struct gpd_timing_data *td = &dev_gpd_data(dev)->td; + + dev_dbg(dev, "%s()\n", __func__); + + if (dev->power.max_time_suspended_ns < 0 || td->break_even_ns == 0) + return true; + + return td->stop_latency_ns + td->start_latency_ns < td->break_even_ns + && td->break_even_ns < dev->power.max_time_suspended_ns; +} + +/** + * 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_dev_off_time_ns; + s64 off_on_time_ns; + ktime_t time_now = ktime_get(); + + 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; + } + + /* + * 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; + + sd_max_off_ns -= ktime_to_ns(ktime_sub(time_now, + sd->power_off_time)); + /* + * 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; + } + + /* + * Check if the devices in the domain can be off enough time. + */ + min_dev_off_time_ns = -1; + list_for_each_entry(pdd, &genpd->dev_list, list_node) { + struct gpd_timing_data *td; + struct device *dev = pdd->dev; + s64 dev_off_time_ns; + + if (!dev->driver || dev->power.max_time_suspended_ns < 0) + continue; + + td = &to_gpd_data(pdd)->td; + dev_off_time_ns = dev->power.max_time_suspended_ns - + (td->start_latency_ns + td->restore_state_latency_ns + + ktime_to_ns(ktime_sub(time_now, + dev->power.suspend_time))); + if (dev_off_time_ns <= off_on_time_ns) + return false; + + if (min_dev_off_time_ns > dev_off_time_ns + || min_dev_off_time_ns < 0) + min_dev_off_time_ns = dev_off_time_ns; + } + + if (min_dev_off_time_ns < 0) { + /* + * There are no latency constraints, so the domain can spend + * arbitrary time in the "off" state. + */ + genpd->max_off_time_ns = -1; + return true; + } + + /* + * The difference between the computed minimum delta and the time needed + * to turn the domain on is the maximum theoretical time this domain can + * spend in the "off" state. + */ + min_dev_off_time_ns -= genpd->power_on_latency_ns; + + /* + * If the difference between the computed minimum delta and the time + * needed to turn the domain off and back on on is smaller than the + * domain's power break even time, removing power from the domain is not + * worth it. + */ + if (genpd->break_even_ns > + min_dev_off_time_ns - genpd->power_off_latency_ns) + return false; + + genpd->max_off_time_ns = min_dev_off_time_ns; + return true; +} + +static bool always_on_power_down_ok(struct dev_pm_domain *domain) +{ + return false; +} + +#else /* !CONFIG_PM_RUNTIME */ + +bool default_stop_ok(struct device *dev) +{ + return false; +} + +#define default_power_down_ok NULL +#define always_on_power_down_ok NULL + +#endif /* !CONFIG_PM_RUNTIME */ + +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, +}; |