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