134 lines
3.3 KiB
C
134 lines
3.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* spu aware cpufreq governor for the cell processor
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*
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* © Copyright IBM Corporation 2006-2008
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*
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* Author: Christian Krafft <krafft@de.ibm.com>
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*/
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#include <linux/cpufreq.h>
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#include <linux/sched.h>
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#include <linux/sched/loadavg.h>
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#include <linux/module.h>
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#include <linux/timer.h>
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#include <linux/workqueue.h>
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#include <linux/atomic.h>
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#include <asm/machdep.h>
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#include <asm/spu.h>
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#define POLL_TIME 100000 /* in µs */
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#define EXP 753 /* exp(-1) in fixed-point */
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struct spu_gov_info_struct {
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unsigned long busy_spus; /* fixed-point */
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struct cpufreq_policy *policy;
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struct delayed_work work;
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unsigned int poll_int; /* µs */
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};
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static DEFINE_PER_CPU(struct spu_gov_info_struct, spu_gov_info);
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static int calc_freq(struct spu_gov_info_struct *info)
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{
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int cpu;
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int busy_spus;
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cpu = info->policy->cpu;
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busy_spus = atomic_read(&cbe_spu_info[cpu_to_node(cpu)].busy_spus);
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info->busy_spus = calc_load(info->busy_spus, EXP, busy_spus * FIXED_1);
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pr_debug("cpu %d: busy_spus=%d, info->busy_spus=%ld\n",
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cpu, busy_spus, info->busy_spus);
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return info->policy->max * info->busy_spus / FIXED_1;
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}
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static void spu_gov_work(struct work_struct *work)
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{
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struct spu_gov_info_struct *info;
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int delay;
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unsigned long target_freq;
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info = container_of(work, struct spu_gov_info_struct, work.work);
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/* after cancel_delayed_work_sync we unset info->policy */
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BUG_ON(info->policy == NULL);
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target_freq = calc_freq(info);
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__cpufreq_driver_target(info->policy, target_freq, CPUFREQ_RELATION_H);
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delay = usecs_to_jiffies(info->poll_int);
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schedule_delayed_work_on(info->policy->cpu, &info->work, delay);
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}
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static void spu_gov_init_work(struct spu_gov_info_struct *info)
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{
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int delay = usecs_to_jiffies(info->poll_int);
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INIT_DEFERRABLE_WORK(&info->work, spu_gov_work);
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schedule_delayed_work_on(info->policy->cpu, &info->work, delay);
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}
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static void spu_gov_cancel_work(struct spu_gov_info_struct *info)
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{
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cancel_delayed_work_sync(&info->work);
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}
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static int spu_gov_start(struct cpufreq_policy *policy)
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{
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unsigned int cpu = policy->cpu;
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struct spu_gov_info_struct *info = &per_cpu(spu_gov_info, cpu);
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struct spu_gov_info_struct *affected_info;
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int i;
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if (!cpu_online(cpu)) {
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printk(KERN_ERR "cpu %d is not online\n", cpu);
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return -EINVAL;
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}
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if (!policy->cur) {
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printk(KERN_ERR "no cpu specified in policy\n");
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return -EINVAL;
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}
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/* initialize spu_gov_info for all affected cpus */
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for_each_cpu(i, policy->cpus) {
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affected_info = &per_cpu(spu_gov_info, i);
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affected_info->policy = policy;
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}
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info->poll_int = POLL_TIME;
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/* setup timer */
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spu_gov_init_work(info);
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return 0;
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}
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static void spu_gov_stop(struct cpufreq_policy *policy)
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{
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unsigned int cpu = policy->cpu;
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struct spu_gov_info_struct *info = &per_cpu(spu_gov_info, cpu);
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int i;
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/* cancel timer */
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spu_gov_cancel_work(info);
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/* clean spu_gov_info for all affected cpus */
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for_each_cpu (i, policy->cpus) {
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info = &per_cpu(spu_gov_info, i);
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info->policy = NULL;
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}
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}
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static struct cpufreq_governor spu_governor = {
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.name = "spudemand",
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.start = spu_gov_start,
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.stop = spu_gov_stop,
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.owner = THIS_MODULE,
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};
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cpufreq_governor_init(spu_governor);
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cpufreq_governor_exit(spu_governor);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");
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