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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2019 Linaro Limited.
*
* Author: Daniel Lezcano <daniel.lezcano@linaro.org>
*
*/
#include <linux/cpu_cooling.h>
#include <linux/cpuidle.h>
#include <linux/err.h>
#include <linux/idle_inject.h>
#include <linux/idr.h>
#include <linux/slab.h>
#include <linux/thermal.h>
/**
* struct cpuidle_cooling_device - data for the idle cooling device
* @ii_dev: an atomic to keep track of the last task exiting the idle cycle
* @state: a normalized integer giving the state of the cooling device
*/
struct cpuidle_cooling_device {
struct idle_inject_device *ii_dev;
unsigned long state;
};
static DEFINE_IDA(cpuidle_ida);
/**
* cpuidle_cooling_runtime - Running time computation
* @idle_duration_us: the idle cooling device
* @state: a percentile based number
*
* The running duration is computed from the idle injection duration
* which is fixed. If we reach 100% of idle injection ratio, that
* means the running duration is zero. If we have a 50% ratio
* injection, that means we have equal duration for idle and for
* running duration.
*
* The formula is deduced as follows:
*
* running = idle x ((100 / ratio) - 1)
*
* For precision purpose for integer math, we use the following:
*
* running = (idle x 100) / ratio - idle
*
* For example, if we have an injected duration of 50%, then we end up
* with 10ms of idle injection and 10ms of running duration.
*
* Return: An unsigned int for a usec based runtime duration.
*/
static unsigned int cpuidle_cooling_runtime(unsigned int idle_duration_us,
unsigned long state)
{
if (!state)
return 0;
return ((idle_duration_us * 100) / state) - idle_duration_us;
}
/**
* cpuidle_cooling_get_max_state - Get the maximum state
* @cdev : the thermal cooling device
* @state : a pointer to the state variable to be filled
*
* The function always returns 100 as the injection ratio. It is
* percentile based for consistency accross different platforms.
*
* Return: The function can not fail, it is always zero
*/
static int cpuidle_cooling_get_max_state(struct thermal_cooling_device *cdev,
unsigned long *state)
{
/*
* Depending on the configuration or the hardware, the running
* cycle and the idle cycle could be different. We want to
* unify that to an 0..100 interval, so the set state
* interface will be the same whatever the platform is.
*
* The state 100% will make the cluster 100% ... idle. A 0%
* injection ratio means no idle injection at all and 50%
* means for 10ms of idle injection, we have 10ms of running
* time.
*/
*state = 100;
return 0;
}
/**
* cpuidle_cooling_get_cur_state - Get the current cooling state
* @cdev: the thermal cooling device
* @state: a pointer to the state
*
* The function just copies the state value from the private thermal
* cooling device structure, the mapping is 1 <-> 1.
*
* Return: The function can not fail, it is always zero
*/
static int cpuidle_cooling_get_cur_state(struct thermal_cooling_device *cdev,
unsigned long *state)
{
struct cpuidle_cooling_device *idle_cdev = cdev->devdata;
*state = idle_cdev->state;
return 0;
}
/**
* cpuidle_cooling_set_cur_state - Set the current cooling state
* @cdev: the thermal cooling device
* @state: the target state
*
* The function checks first if we are initiating the mitigation which
* in turn wakes up all the idle injection tasks belonging to the idle
* cooling device. In any case, it updates the internal state for the
* cooling device.
*
* Return: The function can not fail, it is always zero
*/
static int cpuidle_cooling_set_cur_state(struct thermal_cooling_device *cdev,
unsigned long state)
{
struct cpuidle_cooling_device *idle_cdev = cdev->devdata;
struct idle_inject_device *ii_dev = idle_cdev->ii_dev;
unsigned long current_state = idle_cdev->state;
unsigned int runtime_us, idle_duration_us;
idle_cdev->state = state;
idle_inject_get_duration(ii_dev, &runtime_us, &idle_duration_us);
runtime_us = cpuidle_cooling_runtime(idle_duration_us, state);
idle_inject_set_duration(ii_dev, runtime_us, idle_duration_us);
if (current_state == 0 && state > 0) {
idle_inject_start(ii_dev);
} else if (current_state > 0 && !state) {
idle_inject_stop(ii_dev);
}
return 0;
}
/**
* cpuidle_cooling_ops - thermal cooling device ops
*/
static struct thermal_cooling_device_ops cpuidle_cooling_ops = {
.get_max_state = cpuidle_cooling_get_max_state,
.get_cur_state = cpuidle_cooling_get_cur_state,
.set_cur_state = cpuidle_cooling_set_cur_state,
};
/**
* cpuidle_of_cooling_register - Idle cooling device initialization function
* @drv: a cpuidle driver structure pointer
* @np: a node pointer to a device tree cooling device node
*
* This function is in charge of creating a cooling device per cpuidle
* driver and register it to thermal framework.
*
* Return: zero on success, or negative value corresponding to the
* error detected in the underlying subsystems.
*/
int cpuidle_of_cooling_register(struct device_node *np,
struct cpuidle_driver *drv)
{
struct idle_inject_device *ii_dev;
struct cpuidle_cooling_device *idle_cdev;
struct thermal_cooling_device *cdev;
char dev_name[THERMAL_NAME_LENGTH];
int id, ret;
idle_cdev = kzalloc(sizeof(*idle_cdev), GFP_KERNEL);
if (!idle_cdev) {
ret = -ENOMEM;
goto out;
}
id = ida_simple_get(&cpuidle_ida, 0, 0, GFP_KERNEL);
if (id < 0) {
ret = id;
goto out_kfree;
}
ii_dev = idle_inject_register(drv->cpumask);
if (!ii_dev) {
ret = -EINVAL;
goto out_id;
}
idle_inject_set_duration(ii_dev, TICK_USEC, TICK_USEC);
idle_cdev->ii_dev = ii_dev;
snprintf(dev_name, sizeof(dev_name), "thermal-idle-%d", id);
cdev = thermal_of_cooling_device_register(np, dev_name, idle_cdev,
&cpuidle_cooling_ops);
if (IS_ERR(cdev)) {
ret = PTR_ERR(cdev);
goto out_unregister;
}
return 0;
out_unregister:
idle_inject_unregister(ii_dev);
out_id:
ida_simple_remove(&cpuidle_ida, id);
out_kfree:
kfree(idle_cdev);
out:
return ret;
}
/**
* cpuidle_cooling_register - Idle cooling device initialization function
* @drv: a cpuidle driver structure pointer
*
* This function is in charge of creating a cooling device per cpuidle
* driver and register it to thermal framework.
*
* Return: zero on success, or negative value corresponding to the
* error detected in the underlying subsystems.
*/
int cpuidle_cooling_register(struct cpuidle_driver *drv)
{
return cpuidle_of_cooling_register(NULL, drv);
}
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