--- /dev/null
+/*
+ * 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,
+};
Code Review / kvmfornfv.git / blobdiff