273 lines
7.4 KiB
C
273 lines
7.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2019 Linaro Limited.
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*
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* Author: Daniel Lezcano <daniel.lezcano@linaro.org>
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*
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*/
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#define pr_fmt(fmt) "cpuidle cooling: " fmt
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#include <linux/cpu_cooling.h>
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#include <linux/cpuidle.h>
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/idle_inject.h>
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#include <linux/of_device.h>
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#include <linux/slab.h>
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#include <linux/thermal.h>
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/**
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* struct cpuidle_cooling_device - data for the idle cooling device
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* @ii_dev: an atomic to keep track of the last task exiting the idle cycle
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* @state: a normalized integer giving the state of the cooling device
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*/
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struct cpuidle_cooling_device {
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struct idle_inject_device *ii_dev;
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unsigned long state;
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};
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/**
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* cpuidle_cooling_runtime - Running time computation
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* @idle_duration_us: CPU idle time to inject in microseconds
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* @state: a percentile based number
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*
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* The running duration is computed from the idle injection duration
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* which is fixed. If we reach 100% of idle injection ratio, that
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* means the running duration is zero. If we have a 50% ratio
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* injection, that means we have equal duration for idle and for
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* running duration.
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*
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* The formula is deduced as follows:
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*
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* running = idle x ((100 / ratio) - 1)
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*
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* For precision purpose for integer math, we use the following:
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*
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* running = (idle x 100) / ratio - idle
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*
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* For example, if we have an injected duration of 50%, then we end up
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* with 10ms of idle injection and 10ms of running duration.
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*
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* Return: An unsigned int for a usec based runtime duration.
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*/
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static unsigned int cpuidle_cooling_runtime(unsigned int idle_duration_us,
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unsigned long state)
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{
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if (!state)
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return 0;
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return ((idle_duration_us * 100) / state) - idle_duration_us;
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}
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/**
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* cpuidle_cooling_get_max_state - Get the maximum state
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* @cdev : the thermal cooling device
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* @state : a pointer to the state variable to be filled
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*
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* The function always returns 100 as the injection ratio. It is
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* percentile based for consistency accross different platforms.
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*
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* Return: The function can not fail, it is always zero
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*/
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static int cpuidle_cooling_get_max_state(struct thermal_cooling_device *cdev,
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unsigned long *state)
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{
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/*
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* Depending on the configuration or the hardware, the running
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* cycle and the idle cycle could be different. We want to
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* unify that to an 0..100 interval, so the set state
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* interface will be the same whatever the platform is.
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*
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* The state 100% will make the cluster 100% ... idle. A 0%
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* injection ratio means no idle injection at all and 50%
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* means for 10ms of idle injection, we have 10ms of running
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* time.
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*/
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*state = 100;
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return 0;
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}
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/**
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* cpuidle_cooling_get_cur_state - Get the current cooling state
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* @cdev: the thermal cooling device
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* @state: a pointer to the state
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*
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* The function just copies the state value from the private thermal
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* cooling device structure, the mapping is 1 <-> 1.
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*
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* Return: The function can not fail, it is always zero
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*/
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static int cpuidle_cooling_get_cur_state(struct thermal_cooling_device *cdev,
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unsigned long *state)
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{
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struct cpuidle_cooling_device *idle_cdev = cdev->devdata;
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*state = idle_cdev->state;
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return 0;
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}
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/**
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* cpuidle_cooling_set_cur_state - Set the current cooling state
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* @cdev: the thermal cooling device
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* @state: the target state
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*
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* The function checks first if we are initiating the mitigation which
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* in turn wakes up all the idle injection tasks belonging to the idle
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* cooling device. In any case, it updates the internal state for the
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* cooling device.
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*
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* Return: The function can not fail, it is always zero
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*/
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static int cpuidle_cooling_set_cur_state(struct thermal_cooling_device *cdev,
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unsigned long state)
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{
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struct cpuidle_cooling_device *idle_cdev = cdev->devdata;
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struct idle_inject_device *ii_dev = idle_cdev->ii_dev;
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unsigned long current_state = idle_cdev->state;
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unsigned int runtime_us, idle_duration_us;
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idle_cdev->state = state;
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idle_inject_get_duration(ii_dev, &runtime_us, &idle_duration_us);
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runtime_us = cpuidle_cooling_runtime(idle_duration_us, state);
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idle_inject_set_duration(ii_dev, runtime_us, idle_duration_us);
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if (current_state == 0 && state > 0) {
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idle_inject_start(ii_dev);
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} else if (current_state > 0 && !state) {
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idle_inject_stop(ii_dev);
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}
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return 0;
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}
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/**
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* cpuidle_cooling_ops - thermal cooling device ops
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*/
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static struct thermal_cooling_device_ops cpuidle_cooling_ops = {
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.get_max_state = cpuidle_cooling_get_max_state,
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.get_cur_state = cpuidle_cooling_get_cur_state,
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.set_cur_state = cpuidle_cooling_set_cur_state,
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};
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/**
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* __cpuidle_cooling_register: register the cooling device
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* @drv: a cpuidle driver structure pointer
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* @np: a device node structure pointer used for the thermal binding
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*
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* This function is in charge of allocating the cpuidle cooling device
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* structure, the idle injection, initialize them and register the
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* cooling device to the thermal framework.
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*
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* Return: zero on success, a negative value returned by one of the
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* underlying subsystem in case of error
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*/
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static int __cpuidle_cooling_register(struct device_node *np,
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struct cpuidle_driver *drv)
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{
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struct idle_inject_device *ii_dev;
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struct cpuidle_cooling_device *idle_cdev;
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struct thermal_cooling_device *cdev;
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struct device *dev;
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unsigned int idle_duration_us = TICK_USEC;
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unsigned int latency_us = UINT_MAX;
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char *name;
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int ret;
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idle_cdev = kzalloc(sizeof(*idle_cdev), GFP_KERNEL);
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if (!idle_cdev) {
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ret = -ENOMEM;
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goto out;
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}
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ii_dev = idle_inject_register(drv->cpumask);
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if (!ii_dev) {
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ret = -EINVAL;
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goto out_kfree;
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}
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of_property_read_u32(np, "duration-us", &idle_duration_us);
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of_property_read_u32(np, "exit-latency-us", &latency_us);
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idle_inject_set_duration(ii_dev, TICK_USEC, idle_duration_us);
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idle_inject_set_latency(ii_dev, latency_us);
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idle_cdev->ii_dev = ii_dev;
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dev = get_cpu_device(cpumask_first(drv->cpumask));
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name = kasprintf(GFP_KERNEL, "idle-%s", dev_name(dev));
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if (!name) {
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ret = -ENOMEM;
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goto out_unregister;
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}
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cdev = thermal_of_cooling_device_register(np, name, idle_cdev,
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&cpuidle_cooling_ops);
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if (IS_ERR(cdev)) {
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ret = PTR_ERR(cdev);
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goto out_kfree_name;
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}
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pr_debug("%s: Idle injection set with idle duration=%u, latency=%u\n",
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name, idle_duration_us, latency_us);
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kfree(name);
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return 0;
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out_kfree_name:
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kfree(name);
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out_unregister:
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idle_inject_unregister(ii_dev);
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out_kfree:
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kfree(idle_cdev);
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out:
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return ret;
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}
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/**
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* cpuidle_cooling_register - Idle cooling device initialization function
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* @drv: a cpuidle driver structure pointer
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*
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* This function is in charge of creating a cooling device per cpuidle
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* driver and register it to the thermal framework.
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*
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* Return: zero on success, or negative value corresponding to the
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* error detected in the underlying subsystems.
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*/
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void cpuidle_cooling_register(struct cpuidle_driver *drv)
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{
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struct device_node *cooling_node;
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struct device_node *cpu_node;
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int cpu, ret;
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for_each_cpu(cpu, drv->cpumask) {
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cpu_node = of_cpu_device_node_get(cpu);
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cooling_node = of_get_child_by_name(cpu_node, "thermal-idle");
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of_node_put(cpu_node);
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if (!cooling_node) {
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pr_debug("'thermal-idle' node not found for cpu%d\n", cpu);
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continue;
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}
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ret = __cpuidle_cooling_register(cooling_node, drv);
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of_node_put(cooling_node);
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if (ret) {
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pr_err("Failed to register the cpuidle cooling device" \
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"for cpu%d: %d\n", cpu, ret);
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break;
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}
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}
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}
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