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// SPDX-License-Identifier: GPL-2.0-only
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/pm_qos.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/wait.h>
#include <linux/cpu.h>
#include <linux/cpufreq.h>
#include <asm/prom.h>
#include "windfarm.h"
#define VERSION "0.3"
static int clamped;
static struct wf_control *clamp_control;
static struct dev_pm_qos_request qos_req;
static unsigned int min_freq, max_freq;
static int clamp_set(struct wf_control *ct, s32 value)
{
unsigned int freq;
if (value) {
freq = min_freq;
printk(KERN_INFO "windfarm: Clamping CPU frequency to "
"minimum !\n");
} else {
freq = max_freq;
printk(KERN_INFO "windfarm: CPU frequency unclamped !\n");
}
clamped = value;
return dev_pm_qos_update_request(&qos_req, freq);
}
static int clamp_get(struct wf_control *ct, s32 *value)
{
*value = clamped;
return 0;
}
static s32 clamp_min(struct wf_control *ct)
{
return 0;
}
static s32 clamp_max(struct wf_control *ct)
{
return 1;
}
static const struct wf_control_ops clamp_ops = {
.set_value = clamp_set,
.get_value = clamp_get,
.get_min = clamp_min,
.get_max = clamp_max,
.owner = THIS_MODULE,
};
static int __init wf_cpufreq_clamp_init(void)
{
struct cpufreq_policy *policy;
struct wf_control *clamp;
struct device *dev;
int ret;
policy = cpufreq_cpu_get(0);
if (!policy) {
pr_warn("%s: cpufreq policy not found cpu0\n", __func__);
return -EPROBE_DEFER;
}
min_freq = policy->cpuinfo.min_freq;
max_freq = policy->cpuinfo.max_freq;
cpufreq_cpu_put(policy);
dev = get_cpu_device(0);
if (unlikely(!dev)) {
pr_warn("%s: No cpu device for cpu0\n", __func__);
return -ENODEV;
}
clamp = kmalloc(sizeof(struct wf_control), GFP_KERNEL);
if (clamp == NULL)
return -ENOMEM;
ret = dev_pm_qos_add_request(dev, &qos_req, DEV_PM_QOS_MAX_FREQUENCY,
max_freq);
if (ret < 0) {
pr_err("%s: Failed to add freq constraint (%d)\n", __func__,
ret);
goto free;
}
clamp->ops = &clamp_ops;
clamp->name = "cpufreq-clamp";
ret = wf_register_control(clamp);
if (ret)
goto fail;
clamp_control = clamp;
return 0;
fail:
dev_pm_qos_remove_request(&qos_req);
free:
kfree(clamp);
return ret;
}
static void __exit wf_cpufreq_clamp_exit(void)
{
if (clamp_control) {
wf_unregister_control(clamp_control);
dev_pm_qos_remove_request(&qos_req);
}
}
module_init(wf_cpufreq_clamp_init);
module_exit(wf_cpufreq_clamp_exit);
MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
MODULE_DESCRIPTION("CPU frequency clamp for PowerMacs thermal control");
MODULE_LICENSE("GPL");
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