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483 lines
11 KiB
483 lines
11 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Copyright 2020 Linaro Limited |
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* |
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* Author: Daniel Lezcano <[email protected]> |
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* |
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* The powercap based Dynamic Thermal Power Management framework |
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* provides to the userspace a consistent API to set the power limit |
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* on some devices. |
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* |
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* DTPM defines the functions to create a tree of constraints. Each |
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* parent node is a virtual description of the aggregation of the |
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* children. It propagates the constraints set at its level to its |
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* children and collect the children power information. The leaves of |
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* the tree are the real devices which have the ability to get their |
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* current power consumption and set their power limit. |
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*/ |
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
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#include <linux/dtpm.h> |
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#include <linux/init.h> |
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#include <linux/kernel.h> |
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#include <linux/powercap.h> |
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#include <linux/slab.h> |
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#include <linux/mutex.h> |
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#define DTPM_POWER_LIMIT_FLAG 0 |
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static const char *constraint_name[] = { |
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"Instantaneous", |
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}; |
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static DEFINE_MUTEX(dtpm_lock); |
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static struct powercap_control_type *pct; |
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static struct dtpm *root; |
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static int get_time_window_us(struct powercap_zone *pcz, int cid, u64 *window) |
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{ |
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return -ENOSYS; |
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} |
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static int set_time_window_us(struct powercap_zone *pcz, int cid, u64 window) |
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{ |
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return -ENOSYS; |
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} |
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static int get_max_power_range_uw(struct powercap_zone *pcz, u64 *max_power_uw) |
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{ |
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struct dtpm *dtpm = to_dtpm(pcz); |
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mutex_lock(&dtpm_lock); |
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*max_power_uw = dtpm->power_max - dtpm->power_min; |
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mutex_unlock(&dtpm_lock); |
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return 0; |
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} |
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static int __get_power_uw(struct dtpm *dtpm, u64 *power_uw) |
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{ |
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struct dtpm *child; |
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u64 power; |
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int ret = 0; |
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if (dtpm->ops) { |
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*power_uw = dtpm->ops->get_power_uw(dtpm); |
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return 0; |
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} |
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*power_uw = 0; |
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list_for_each_entry(child, &dtpm->children, sibling) { |
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ret = __get_power_uw(child, &power); |
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if (ret) |
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break; |
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*power_uw += power; |
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} |
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return ret; |
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} |
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static int get_power_uw(struct powercap_zone *pcz, u64 *power_uw) |
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{ |
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struct dtpm *dtpm = to_dtpm(pcz); |
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int ret; |
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mutex_lock(&dtpm_lock); |
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ret = __get_power_uw(dtpm, power_uw); |
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mutex_unlock(&dtpm_lock); |
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return ret; |
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} |
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static void __dtpm_rebalance_weight(struct dtpm *dtpm) |
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{ |
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struct dtpm *child; |
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list_for_each_entry(child, &dtpm->children, sibling) { |
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pr_debug("Setting weight '%d' for '%s'\n", |
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child->weight, child->zone.name); |
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child->weight = DIV64_U64_ROUND_CLOSEST( |
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child->power_max * 1024, dtpm->power_max); |
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__dtpm_rebalance_weight(child); |
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} |
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} |
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static void __dtpm_sub_power(struct dtpm *dtpm) |
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{ |
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struct dtpm *parent = dtpm->parent; |
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while (parent) { |
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parent->power_min -= dtpm->power_min; |
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parent->power_max -= dtpm->power_max; |
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parent->power_limit -= dtpm->power_limit; |
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parent = parent->parent; |
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} |
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__dtpm_rebalance_weight(root); |
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} |
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static void __dtpm_add_power(struct dtpm *dtpm) |
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{ |
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struct dtpm *parent = dtpm->parent; |
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while (parent) { |
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parent->power_min += dtpm->power_min; |
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parent->power_max += dtpm->power_max; |
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parent->power_limit += dtpm->power_limit; |
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parent = parent->parent; |
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} |
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__dtpm_rebalance_weight(root); |
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} |
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/** |
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* dtpm_update_power - Update the power on the dtpm |
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* @dtpm: a pointer to a dtpm structure to update |
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* @power_min: a u64 representing the new power_min value |
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* @power_max: a u64 representing the new power_max value |
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* |
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* Function to update the power values of the dtpm node specified in |
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* parameter. These new values will be propagated to the tree. |
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* |
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* Return: zero on success, -EINVAL if the values are inconsistent |
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*/ |
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int dtpm_update_power(struct dtpm *dtpm, u64 power_min, u64 power_max) |
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{ |
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int ret = 0; |
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mutex_lock(&dtpm_lock); |
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if (power_min == dtpm->power_min && power_max == dtpm->power_max) |
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goto unlock; |
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if (power_max < power_min) { |
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ret = -EINVAL; |
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goto unlock; |
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} |
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__dtpm_sub_power(dtpm); |
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dtpm->power_min = power_min; |
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dtpm->power_max = power_max; |
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if (!test_bit(DTPM_POWER_LIMIT_FLAG, &dtpm->flags)) |
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dtpm->power_limit = power_max; |
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__dtpm_add_power(dtpm); |
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unlock: |
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mutex_unlock(&dtpm_lock); |
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return ret; |
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} |
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/** |
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* dtpm_release_zone - Cleanup when the node is released |
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* @pcz: a pointer to a powercap_zone structure |
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* |
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* Do some housecleaning and update the weight on the tree. The |
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* release will be denied if the node has children. This function must |
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* be called by the specific release callback of the different |
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* backends. |
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* |
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* Return: 0 on success, -EBUSY if there are children |
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*/ |
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int dtpm_release_zone(struct powercap_zone *pcz) |
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{ |
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struct dtpm *dtpm = to_dtpm(pcz); |
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struct dtpm *parent = dtpm->parent; |
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mutex_lock(&dtpm_lock); |
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if (!list_empty(&dtpm->children)) { |
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mutex_unlock(&dtpm_lock); |
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return -EBUSY; |
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} |
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if (parent) |
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list_del(&dtpm->sibling); |
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__dtpm_sub_power(dtpm); |
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mutex_unlock(&dtpm_lock); |
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if (dtpm->ops) |
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dtpm->ops->release(dtpm); |
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if (root == dtpm) |
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root = NULL; |
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kfree(dtpm); |
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return 0; |
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} |
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static int __get_power_limit_uw(struct dtpm *dtpm, int cid, u64 *power_limit) |
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{ |
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*power_limit = dtpm->power_limit; |
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return 0; |
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} |
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static int get_power_limit_uw(struct powercap_zone *pcz, |
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int cid, u64 *power_limit) |
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{ |
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struct dtpm *dtpm = to_dtpm(pcz); |
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int ret; |
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mutex_lock(&dtpm_lock); |
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ret = __get_power_limit_uw(dtpm, cid, power_limit); |
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mutex_unlock(&dtpm_lock); |
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return ret; |
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} |
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/* |
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* Set the power limit on the nodes, the power limit is distributed |
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* given the weight of the children. |
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* |
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* The dtpm node lock must be held when calling this function. |
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*/ |
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static int __set_power_limit_uw(struct dtpm *dtpm, int cid, u64 power_limit) |
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{ |
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struct dtpm *child; |
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int ret = 0; |
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u64 power; |
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/* |
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* A max power limitation means we remove the power limit, |
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* otherwise we set a constraint and flag the dtpm node. |
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*/ |
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if (power_limit == dtpm->power_max) { |
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clear_bit(DTPM_POWER_LIMIT_FLAG, &dtpm->flags); |
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} else { |
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set_bit(DTPM_POWER_LIMIT_FLAG, &dtpm->flags); |
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} |
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pr_debug("Setting power limit for '%s': %llu uW\n", |
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dtpm->zone.name, power_limit); |
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/* |
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* Only leaves of the dtpm tree has ops to get/set the power |
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*/ |
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if (dtpm->ops) { |
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dtpm->power_limit = dtpm->ops->set_power_uw(dtpm, power_limit); |
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} else { |
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dtpm->power_limit = 0; |
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list_for_each_entry(child, &dtpm->children, sibling) { |
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/* |
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* Integer division rounding will inevitably |
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* lead to a different min or max value when |
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* set several times. In order to restore the |
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* initial value, we force the child's min or |
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* max power every time if the constraint is |
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* at the boundaries. |
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*/ |
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if (power_limit == dtpm->power_max) { |
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power = child->power_max; |
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} else if (power_limit == dtpm->power_min) { |
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power = child->power_min; |
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} else { |
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power = DIV_ROUND_CLOSEST_ULL( |
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power_limit * child->weight, 1024); |
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} |
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pr_debug("Setting power limit for '%s': %llu uW\n", |
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child->zone.name, power); |
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ret = __set_power_limit_uw(child, cid, power); |
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if (!ret) |
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ret = __get_power_limit_uw(child, cid, &power); |
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if (ret) |
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break; |
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dtpm->power_limit += power; |
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} |
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} |
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return ret; |
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} |
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static int set_power_limit_uw(struct powercap_zone *pcz, |
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int cid, u64 power_limit) |
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{ |
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struct dtpm *dtpm = to_dtpm(pcz); |
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int ret; |
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mutex_lock(&dtpm_lock); |
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/* |
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* Don't allow values outside of the power range previously |
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* set when initializing the power numbers. |
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*/ |
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power_limit = clamp_val(power_limit, dtpm->power_min, dtpm->power_max); |
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ret = __set_power_limit_uw(dtpm, cid, power_limit); |
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pr_debug("%s: power limit: %llu uW, power max: %llu uW\n", |
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dtpm->zone.name, dtpm->power_limit, dtpm->power_max); |
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mutex_unlock(&dtpm_lock); |
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return ret; |
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} |
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static const char *get_constraint_name(struct powercap_zone *pcz, int cid) |
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{ |
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return constraint_name[cid]; |
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} |
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static int get_max_power_uw(struct powercap_zone *pcz, int id, u64 *max_power) |
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{ |
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struct dtpm *dtpm = to_dtpm(pcz); |
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mutex_lock(&dtpm_lock); |
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*max_power = dtpm->power_max; |
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mutex_unlock(&dtpm_lock); |
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return 0; |
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} |
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static struct powercap_zone_constraint_ops constraint_ops = { |
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.set_power_limit_uw = set_power_limit_uw, |
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.get_power_limit_uw = get_power_limit_uw, |
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.set_time_window_us = set_time_window_us, |
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.get_time_window_us = get_time_window_us, |
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.get_max_power_uw = get_max_power_uw, |
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.get_name = get_constraint_name, |
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}; |
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static struct powercap_zone_ops zone_ops = { |
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.get_max_power_range_uw = get_max_power_range_uw, |
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.get_power_uw = get_power_uw, |
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.release = dtpm_release_zone, |
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}; |
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/** |
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* dtpm_alloc - Allocate and initialize a dtpm struct |
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* @name: a string specifying the name of the node |
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* |
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* Return: a struct dtpm pointer, NULL in case of error |
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*/ |
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struct dtpm *dtpm_alloc(struct dtpm_ops *ops) |
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{ |
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struct dtpm *dtpm; |
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dtpm = kzalloc(sizeof(*dtpm), GFP_KERNEL); |
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if (dtpm) { |
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INIT_LIST_HEAD(&dtpm->children); |
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INIT_LIST_HEAD(&dtpm->sibling); |
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dtpm->weight = 1024; |
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dtpm->ops = ops; |
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} |
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return dtpm; |
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} |
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/** |
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* dtpm_unregister - Unregister a dtpm node from the hierarchy tree |
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* @dtpm: a pointer to a dtpm structure corresponding to the node to be removed |
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* |
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* Call the underlying powercap unregister function. That will call |
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* the release callback of the powercap zone. |
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*/ |
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void dtpm_unregister(struct dtpm *dtpm) |
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{ |
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powercap_unregister_zone(pct, &dtpm->zone); |
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pr_info("Unregistered dtpm node '%s'\n", dtpm->zone.name); |
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} |
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/** |
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* dtpm_register - Register a dtpm node in the hierarchy tree |
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* @name: a string specifying the name of the node |
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* @dtpm: a pointer to a dtpm structure corresponding to the new node |
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* @parent: a pointer to a dtpm structure corresponding to the parent node |
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* |
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* Create a dtpm node in the tree. If no parent is specified, the node |
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* is the root node of the hierarchy. If the root node already exists, |
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* then the registration will fail. The powercap controller must be |
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* initialized before calling this function. |
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* |
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* The dtpm structure must be initialized with the power numbers |
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* before calling this function. |
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* |
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* Return: zero on success, a negative value in case of error: |
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* -EAGAIN: the function is called before the framework is initialized. |
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* -EBUSY: the root node is already inserted |
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* -EINVAL: * there is no root node yet and @parent is specified |
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* * no all ops are defined |
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* * parent have ops which are reserved for leaves |
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* Other negative values are reported back from the powercap framework |
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*/ |
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int dtpm_register(const char *name, struct dtpm *dtpm, struct dtpm *parent) |
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{ |
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struct powercap_zone *pcz; |
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if (!pct) |
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return -EAGAIN; |
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if (root && !parent) |
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return -EBUSY; |
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if (!root && parent) |
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return -EINVAL; |
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if (parent && parent->ops) |
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return -EINVAL; |
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if (!dtpm) |
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return -EINVAL; |
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if (dtpm->ops && !(dtpm->ops->set_power_uw && |
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dtpm->ops->get_power_uw && |
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dtpm->ops->release)) |
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return -EINVAL; |
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pcz = powercap_register_zone(&dtpm->zone, pct, name, |
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parent ? &parent->zone : NULL, |
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&zone_ops, MAX_DTPM_CONSTRAINTS, |
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&constraint_ops); |
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if (IS_ERR(pcz)) |
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return PTR_ERR(pcz); |
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mutex_lock(&dtpm_lock); |
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if (parent) { |
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list_add_tail(&dtpm->sibling, &parent->children); |
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dtpm->parent = parent; |
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} else { |
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root = dtpm; |
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} |
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__dtpm_add_power(dtpm); |
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pr_info("Registered dtpm node '%s' / %llu-%llu uW, \n", |
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dtpm->zone.name, dtpm->power_min, dtpm->power_max); |
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mutex_unlock(&dtpm_lock); |
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return 0; |
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} |
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static int __init dtpm_init(void) |
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{ |
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struct dtpm_descr **dtpm_descr; |
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pct = powercap_register_control_type(NULL, "dtpm", NULL); |
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if (IS_ERR(pct)) { |
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pr_err("Failed to register control type\n"); |
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return PTR_ERR(pct); |
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} |
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for_each_dtpm_table(dtpm_descr) |
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(*dtpm_descr)->init(*dtpm_descr); |
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return 0; |
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} |
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late_initcall(dtpm_init);
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