1 files changed, 321 insertions, 0 deletions
diff --git a/drivers/base/power/domain_governor.c b/drivers/base/power/domain_governor.c
new file mode 100644
index 000000000..490ed7deb
--- /dev/null
+++ b/drivers/base/power/domain_governor.c
@@ -0,0 +1,321 @@
+// 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) {
+		/*
+		 * 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 = dev_gpd_data(dev)->td.effective_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 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 generic_pm_domain *sd = link->child;
+		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;
+
+		/*
+		 * 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->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.
+ *
+ * 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;
+
+	if (!genpd->max_off_time_changed) {
+		genpd->state_idx = genpd->cached_power_down_state_idx;
+		return genpd->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)
+		link->parent->max_off_time_changed = true;
+
+	genpd->max_off_time_ns = -1;
+	genpd->max_off_time_changed = false;
+	genpd->cached_power_down_ok = true;
+	genpd->state_idx = genpd->state_count - 1;
+
+	/* Find a state to power down to, starting from the deepest. */
+	while (!__default_power_down_ok(pd, genpd->state_idx)) {
+		if (genpd->state_idx == 0) {
+			genpd->cached_power_down_ok = false;
+			break;
+		}
+		genpd->state_idx--;
+	}
+
+	genpd->cached_power_down_state_idx = genpd->state_idx;
+	return genpd->cached_power_down_ok;
+}
+
+static bool always_on_power_down_ok(struct dev_pm_domain *domain)
+{
+	return false;
+}
+
+#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;
+	s64 idle_duration_ns;
+	int cpu, i;
+
+	/* Validate dev PM QoS constraints. */
+	if (!default_power_down_ok(pd))
+		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, ktime_get()));
+	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 = {
+	.power_down_ok = always_on_power_down_ok,
+	.suspend_ok = default_suspend_ok,
+};