1 files changed, 473 insertions, 0 deletions
diff --git a/drivers/powercap/dtpm.c b/drivers/powercap/dtpm.c
new file mode 100644
index 000000000000..5b6857e9b064
--- /dev/null
+++ b/drivers/powercap/dtpm.c
@@ -0,0 +1,473 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2020 Linaro Limited
+ *
+ * Author: Daniel Lezcano <daniel.lezcano@linaro.org>
+ *
+ * The powercap based Dynamic Thermal Power Management framework
+ * provides to the userspace a consistent API to set the power limit
+ * on some devices.
+ *
+ * DTPM defines the functions to create a tree of constraints. Each
+ * parent node is a virtual description of the aggregation of the
+ * children. It propagates the constraints set at its level to its
+ * children and collect the children power information. The leaves of
+ * the tree are the real devices which have the ability to get their
+ * current power consumption and set their power limit.
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/dtpm.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/powercap.h>
+#include <linux/slab.h>
+#include <linux/mutex.h>
+
+#define DTPM_POWER_LIMIT_FLAG BIT(0)
+
+static const char *constraint_name[] = {
+	"Instantaneous",
+};
+
+static DEFINE_MUTEX(dtpm_lock);
+static struct powercap_control_type *pct;
+static struct dtpm *root;
+
+static int get_time_window_us(struct powercap_zone *pcz, int cid, u64 *window)
+{
+	return -ENOSYS;
+}
+
+static int set_time_window_us(struct powercap_zone *pcz, int cid, u64 window)
+{
+	return -ENOSYS;
+}
+
+static int get_max_power_range_uw(struct powercap_zone *pcz, u64 *max_power_uw)
+{
+	struct dtpm *dtpm = to_dtpm(pcz);
+
+	mutex_lock(&dtpm_lock);
+	*max_power_uw = dtpm->power_max - dtpm->power_min;
+	mutex_unlock(&dtpm_lock);
+
+	return 0;
+}
+
+static int __get_power_uw(struct dtpm *dtpm, u64 *power_uw)
+{
+	struct dtpm *child;
+	u64 power;
+	int ret = 0;
+
+	if (dtpm->ops) {
+		*power_uw = dtpm->ops->get_power_uw(dtpm);
+		return 0;
+	}
+
+	*power_uw = 0;
+
+	list_for_each_entry(child, &dtpm->children, sibling) {
+		ret = __get_power_uw(child, &power);
+		if (ret)
+			break;
+		*power_uw += power;
+	}
+
+	return ret;
+}
+
+static int get_power_uw(struct powercap_zone *pcz, u64 *power_uw)
+{
+	struct dtpm *dtpm = to_dtpm(pcz);
+	int ret;
+
+	mutex_lock(&dtpm_lock);
+	ret = __get_power_uw(dtpm, power_uw);
+	mutex_unlock(&dtpm_lock);
+
+	return ret;
+}
+
+static void __dtpm_rebalance_weight(struct dtpm *dtpm)
+{
+	struct dtpm *child;
+
+	list_for_each_entry(child, &dtpm->children, sibling) {
+
+		pr_debug("Setting weight '%d' for '%s'\n",
+			 child->weight, child->zone.name);
+
+		child->weight = DIV_ROUND_CLOSEST(child->power_max * 1024,
+						  dtpm->power_max);
+
+		__dtpm_rebalance_weight(child);
+	}
+}
+
+static void __dtpm_sub_power(struct dtpm *dtpm)
+{
+	struct dtpm *parent = dtpm->parent;
+
+	while (parent) {
+		parent->power_min -= dtpm->power_min;
+		parent->power_max -= dtpm->power_max;
+		parent->power_limit -= dtpm->power_limit;
+		parent = parent->parent;
+	}
+
+	__dtpm_rebalance_weight(root);
+}
+
+static void __dtpm_add_power(struct dtpm *dtpm)
+{
+	struct dtpm *parent = dtpm->parent;
+
+	while (parent) {
+		parent->power_min += dtpm->power_min;
+		parent->power_max += dtpm->power_max;
+		parent->power_limit += dtpm->power_limit;
+		parent = parent->parent;
+	}
+
+	__dtpm_rebalance_weight(root);
+}
+
+/**
+ * dtpm_update_power - Update the power on the dtpm
+ * @dtpm: a pointer to a dtpm structure to update
+ * @power_min: a u64 representing the new power_min value
+ * @power_max: a u64 representing the new power_max value
+ *
+ * Function to update the power values of the dtpm node specified in
+ * parameter. These new values will be propagated to the tree.
+ *
+ * Return: zero on success, -EINVAL if the values are inconsistent
+ */
+int dtpm_update_power(struct dtpm *dtpm, u64 power_min, u64 power_max)
+{
+	mutex_lock(&dtpm_lock);
+
+	if (power_min == dtpm->power_min && power_max == dtpm->power_max)
+		return 0;
+
+	if (power_max < power_min)
+		return -EINVAL;
+
+	__dtpm_sub_power(dtpm);
+
+	dtpm->power_min = power_min;
+	dtpm->power_max = power_max;
+	if (!test_bit(DTPM_POWER_LIMIT_FLAG, &dtpm->flags))
+		dtpm->power_limit = power_max;
+
+	__dtpm_add_power(dtpm);
+
+	mutex_unlock(&dtpm_lock);
+
+	return 0;
+}
+
+/**
+ * dtpm_release_zone - Cleanup when the node is released
+ * @pcz: a pointer to a powercap_zone structure
+ *
+ * Do some housecleaning and update the weight on the tree. The
+ * release will be denied if the node has children. This function must
+ * be called by the specific release callback of the different
+ * backends.
+ *
+ * Return: 0 on success, -EBUSY if there are children
+ */
+int dtpm_release_zone(struct powercap_zone *pcz)
+{
+	struct dtpm *dtpm = to_dtpm(pcz);
+	struct dtpm *parent = dtpm->parent;
+
+	mutex_lock(&dtpm_lock);
+
+	if (!list_empty(&dtpm->children))
+		return -EBUSY;
+
+	if (parent)
+		list_del(&dtpm->sibling);
+
+	__dtpm_sub_power(dtpm);
+
+	mutex_unlock(&dtpm_lock);
+
+	if (dtpm->ops)
+		dtpm->ops->release(dtpm);
+
+	kfree(dtpm);
+
+	return 0;
+}
+
+static int __get_power_limit_uw(struct dtpm *dtpm, int cid, u64 *power_limit)
+{
+	*power_limit = dtpm->power_limit;
+	return 0;
+}
+
+static int get_power_limit_uw(struct powercap_zone *pcz,
+			      int cid, u64 *power_limit)
+{
+	struct dtpm *dtpm = to_dtpm(pcz);
+	int ret;
+
+	mutex_lock(&dtpm_lock);
+	ret = __get_power_limit_uw(dtpm, cid, power_limit);
+	mutex_unlock(&dtpm_lock);
+
+	return ret;
+}
+
+/*
+ * Set the power limit on the nodes, the power limit is distributed
+ * given the weight of the children.
+ *
+ * The dtpm node lock must be held when calling this function.
+ */
+static int __set_power_limit_uw(struct dtpm *dtpm, int cid, u64 power_limit)
+{
+	struct dtpm *child;
+	int ret = 0;
+	u64 power;
+
+	/*
+	 * A max power limitation means we remove the power limit,
+	 * otherwise we set a constraint and flag the dtpm node.
+	 */
+	if (power_limit == dtpm->power_max) {
+		clear_bit(DTPM_POWER_LIMIT_FLAG, &dtpm->flags);
+	} else {
+		set_bit(DTPM_POWER_LIMIT_FLAG, &dtpm->flags);
+	}
+
+	pr_debug("Setting power limit for '%s': %llu uW\n",
+		 dtpm->zone.name, power_limit);
+
+	/*
+	 * Only leaves of the dtpm tree has ops to get/set the power
+	 */
+	if (dtpm->ops) {
+		dtpm->power_limit = dtpm->ops->set_power_uw(dtpm, power_limit);
+	} else {
+		dtpm->power_limit = 0;
+
+		list_for_each_entry(child, &dtpm->children, sibling) {
+
+			/*
+			 * Integer division rounding will inevitably
+			 * lead to a different min or max value when
+			 * set several times. In order to restore the
+			 * initial value, we force the child's min or
+			 * max power every time if the constraint is
+			 * at the boundaries.
+			 */
+			if (power_limit == dtpm->power_max) {
+				power = child->power_max;
+			} else if (power_limit == dtpm->power_min) {
+				power = child->power_min;
+			} else {
+				power = DIV_ROUND_CLOSEST(
+					power_limit * child->weight, 1024);
+			}
+
+			pr_debug("Setting power limit for '%s': %llu uW\n",
+				 child->zone.name, power);
+
+			ret = __set_power_limit_uw(child, cid, power);
+			if (!ret)
+				ret = __get_power_limit_uw(child, cid, &power);
+
+			if (ret)
+				break;
+
+			dtpm->power_limit += power;
+		}
+	}
+
+	return ret;
+}
+
+static int set_power_limit_uw(struct powercap_zone *pcz,
+			      int cid, u64 power_limit)
+{
+	struct dtpm *dtpm = to_dtpm(pcz);
+	int ret;
+
+	mutex_lock(&dtpm_lock);
+
+	/*
+	 * Don't allow values outside of the power range previously
+	 * set when initializing the power numbers.
+	 */
+	power_limit = clamp_val(power_limit, dtpm->power_min, dtpm->power_max);
+
+	ret = __set_power_limit_uw(dtpm, cid, power_limit);
+
+	pr_debug("%s: power limit: %llu uW, power max: %llu uW\n",
+		 dtpm->zone.name, dtpm->power_limit, dtpm->power_max);
+
+	mutex_unlock(&dtpm_lock);
+
+	return ret;
+}
+
+static const char *get_constraint_name(struct powercap_zone *pcz, int cid)
+{
+	return constraint_name[cid];
+}
+
+static int get_max_power_uw(struct powercap_zone *pcz, int id, u64 *max_power)
+{
+	struct dtpm *dtpm = to_dtpm(pcz);
+
+	mutex_lock(&dtpm_lock);
+	*max_power = dtpm->power_max;
+	mutex_unlock(&dtpm_lock);
+
+	return 0;
+}
+
+static struct powercap_zone_constraint_ops constraint_ops = {
+	.set_power_limit_uw = set_power_limit_uw,
+	.get_power_limit_uw = get_power_limit_uw,
+	.set_time_window_us = set_time_window_us,
+	.get_time_window_us = get_time_window_us,
+	.get_max_power_uw = get_max_power_uw,
+	.get_name = get_constraint_name,
+};
+
+static struct powercap_zone_ops zone_ops = {
+	.get_max_power_range_uw = get_max_power_range_uw,
+	.get_power_uw = get_power_uw,
+	.release = dtpm_release_zone,
+};
+
+/**
+ * dtpm_alloc - Allocate and initialize a dtpm struct
+ * @name: a string specifying the name of the node
+ *
+ * Return: a struct dtpm pointer, NULL in case of error
+ */
+struct dtpm *dtpm_alloc(struct dtpm_ops *ops)
+{
+	struct dtpm *dtpm;
+
+	dtpm = kzalloc(sizeof(*dtpm), GFP_KERNEL);
+	if (dtpm) {
+		INIT_LIST_HEAD(&dtpm->children);
+		INIT_LIST_HEAD(&dtpm->sibling);
+		dtpm->weight = 1024;
+		dtpm->ops = ops;
+	}
+
+	return dtpm;
+}
+
+/**
+ * dtpm_unregister - Unregister a dtpm node from the hierarchy tree
+ * @dtpm: a pointer to a dtpm structure corresponding to the node to be removed
+ *
+ * Call the underlying powercap unregister function. That will call
+ * the release callback of the powercap zone.
+ */
+void dtpm_unregister(struct dtpm *dtpm)
+{
+	powercap_unregister_zone(pct, &dtpm->zone);
+
+	pr_info("Unregistered dtpm node '%s'\n", dtpm->zone.name);
+}
+
+/**
+ * dtpm_register - Register a dtpm node in the hierarchy tree
+ * @name: a string specifying the name of the node
+ * @dtpm: a pointer to a dtpm structure corresponding to the new node
+ * @parent: a pointer to a dtpm structure corresponding to the parent node
+ *
+ * Create a dtpm node in the tree. If no parent is specified, the node
+ * is the root node of the hierarchy. If the root node already exists,
+ * then the registration will fail. The powercap controller must be
+ * initialized before calling this function.
+ *
+ * The dtpm structure must be initialized with the power numbers
+ * before calling this function.
+ *
+ * Return: zero on success, a negative value in case of error:
+ *  -EAGAIN: the function is called before the framework is initialized.
+ *  -EBUSY: the root node is already inserted
+ *  -EINVAL: * there is no root node yet and @parent is specified
+ *           * no all ops are defined
+ *           * parent have ops which are reserved for leaves
+ *   Other negative values are reported back from the powercap framework
+ */
+int dtpm_register(const char *name, struct dtpm *dtpm, struct dtpm *parent)
+{
+	struct powercap_zone *pcz;
+
+	if (!pct)
+		return -EAGAIN;
+
+	if (root && !parent)
+		return -EBUSY;
+
+	if (!root && parent)
+		return -EINVAL;
+
+	if (parent && parent->ops)
+		return -EINVAL;
+
+	if (!dtpm)
+		return -EINVAL;
+
+	if (dtpm->ops && !(dtpm->ops->set_power_uw &&
+			   dtpm->ops->get_power_uw &&
+			   dtpm->ops->release))
+		return -EINVAL;
+
+	pcz = powercap_register_zone(&dtpm->zone, pct, name,
+				     parent ? &parent->zone : NULL,
+				     &zone_ops, MAX_DTPM_CONSTRAINTS,
+				     &constraint_ops);
+	if (IS_ERR(pcz))
+		return PTR_ERR(pcz);
+
+	mutex_lock(&dtpm_lock);
+
+	if (parent) {
+		list_add_tail(&dtpm->sibling, &parent->children);
+		dtpm->parent = parent;
+	} else {
+		root = dtpm;
+	}
+
+	__dtpm_add_power(dtpm);
+
+	pr_info("Registered dtpm node '%s' / %llu-%llu uW, \n",
+		dtpm->zone.name, dtpm->power_min, dtpm->power_max);
+
+	mutex_unlock(&dtpm_lock);
+
+	return 0;
+}
+
+static int __init dtpm_init(void)
+{
+	struct dtpm_descr **dtpm_descr;
+
+	pct = powercap_register_control_type(NULL, "dtpm", NULL);
+	if (!pct) {
+		pr_err("Failed to register control type\n");
+		return -EINVAL;
+	}
+
+	for_each_dtpm_table(dtpm_descr)
+		(*dtpm_descr)->init(*dtpm_descr);
+
+	return 0;
+}
+late_initcall(dtpm_init);