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1// SPDX-License-Identifier: GPL-2.0-only2#include <linux/types.h>3#include <linux/errno.h>4#include <linux/kernel.h>5#include <linux/delay.h>6#include <linux/pm_qos.h>7#include <linux/slab.h>8#include <linux/init.h>9#include <linux/wait.h>10#include <linux/cpu.h>11#include <linux/cpufreq.h>12 13#include "windfarm.h"14 15#define VERSION "0.3"16 17static int clamped;18static struct wf_control *clamp_control;19static struct freq_qos_request qos_req;20static unsigned int min_freq, max_freq;21 22static int clamp_set(struct wf_control *ct, s32 value)23{24 unsigned int freq;25 26 if (value) {27 freq = min_freq;28 printk(KERN_INFO "windfarm: Clamping CPU frequency to "29 "minimum !\n");30 } else {31 freq = max_freq;32 printk(KERN_INFO "windfarm: CPU frequency unclamped !\n");33 }34 clamped = value;35 36 return freq_qos_update_request(&qos_req, freq);37}38 39static int clamp_get(struct wf_control *ct, s32 *value)40{41 *value = clamped;42 return 0;43}44 45static s32 clamp_min(struct wf_control *ct)46{47 return 0;48}49 50static s32 clamp_max(struct wf_control *ct)51{52 return 1;53}54 55static const struct wf_control_ops clamp_ops = {56 .set_value = clamp_set,57 .get_value = clamp_get,58 .get_min = clamp_min,59 .get_max = clamp_max,60 .owner = THIS_MODULE,61};62 63static int __init wf_cpufreq_clamp_init(void)64{65 struct cpufreq_policy *policy;66 struct wf_control *clamp;67 struct device *dev;68 int ret;69 70 policy = cpufreq_cpu_get(0);71 if (!policy) {72 pr_warn("%s: cpufreq policy not found cpu0\n", __func__);73 return -EPROBE_DEFER;74 }75 76 min_freq = policy->cpuinfo.min_freq;77 max_freq = policy->cpuinfo.max_freq;78 79 ret = freq_qos_add_request(&policy->constraints, &qos_req, FREQ_QOS_MAX,80 max_freq);81 82 cpufreq_cpu_put(policy);83 84 if (ret < 0) {85 pr_err("%s: Failed to add freq constraint (%d)\n", __func__,86 ret);87 return ret;88 }89 90 dev = get_cpu_device(0);91 if (unlikely(!dev)) {92 pr_warn("%s: No cpu device for cpu0\n", __func__);93 ret = -ENODEV;94 goto fail;95 }96 97 clamp = kmalloc(sizeof(struct wf_control), GFP_KERNEL);98 if (clamp == NULL) {99 ret = -ENOMEM;100 goto fail;101 }102 103 clamp->ops = &clamp_ops;104 clamp->name = "cpufreq-clamp";105 ret = wf_register_control(clamp);106 if (ret)107 goto free;108 109 clamp_control = clamp;110 return 0;111 112 free:113 kfree(clamp);114 fail:115 freq_qos_remove_request(&qos_req);116 return ret;117}118 119static void __exit wf_cpufreq_clamp_exit(void)120{121 if (clamp_control) {122 wf_unregister_control(clamp_control);123 freq_qos_remove_request(&qos_req);124 }125}126 127 128module_init(wf_cpufreq_clamp_init);129module_exit(wf_cpufreq_clamp_exit);130 131MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");132MODULE_DESCRIPTION("CPU frequency clamp for PowerMacs thermal control");133MODULE_LICENSE("GPL");134 135