// 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/slab.h> #include <linux/init.h> #include <linux/wait.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 int clamp_notifier_call(struct notifier_block *self, unsigned long event, void *data) { struct cpufreq_policy *p = data; unsigned long max_freq; if (event != CPUFREQ_ADJUST) return 0; max_freq = clamped ? (p->cpuinfo.min_freq) : (p->cpuinfo.max_freq); cpufreq_verify_within_limits(p, 0, max_freq); return 0; } static struct notifier_block clamp_notifier = { .notifier_call = clamp_notifier_call, }; static int clamp_set(struct wf_control *ct, s32 value) { if (value) printk(KERN_INFO "windfarm: Clamping CPU frequency to " "minimum !\n"); else printk(KERN_INFO "windfarm: CPU frequency unclamped !\n"); clamped = value; cpufreq_update_policy(0); return 0; } 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 wf_control *clamp; clamp = kmalloc(sizeof(struct wf_control), GFP_KERNEL); if (clamp == NULL) return -ENOMEM; cpufreq_register_notifier(&clamp_notifier, CPUFREQ_POLICY_NOTIFIER); clamp->ops = &clamp_ops; clamp->name = "cpufreq-clamp"; if (wf_register_control(clamp)) goto fail; clamp_control = clamp; return 0; fail: kfree(clamp); return -ENODEV; } static void __exit wf_cpufreq_clamp_exit(void) { if (clamp_control) wf_unregister_control(clamp_control); } 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");