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- // 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 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 = DIV64_U64_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)
- {
- int ret = 0;
- mutex_lock(&dtpm_lock);
- if (power_min == dtpm->power_min && power_max == dtpm->power_max)
- goto unlock;
- if (power_max < power_min) {
- ret = -EINVAL;
- goto unlock;
- }
- __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);
- unlock:
- mutex_unlock(&dtpm_lock);
- return ret;
- }
- /**
- * 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)) {
- mutex_unlock(&dtpm_lock);
- return -EBUSY;
- }
- if (parent)
- list_del(&dtpm->sibling);
- __dtpm_sub_power(dtpm);
- mutex_unlock(&dtpm_lock);
- if (dtpm->ops)
- dtpm->ops->release(dtpm);
- if (root == dtpm)
- root = NULL;
- 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_ULL(
- 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 (IS_ERR(pct)) {
- pr_err("Failed to register control type\n");
- return PTR_ERR(pct);
- }
- for_each_dtpm_table(dtpm_descr)
- (*dtpm_descr)->init(*dtpm_descr);
- return 0;
- }
- late_initcall(dtpm_init);
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