1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * spu aware cpufreq governor for the cell processor
4 *
5 * �� Copyright IBM Corporation 2006-2008
6 *
7 * Author: Christian Krafft <krafft@de.ibm.com>
8 */
9
10#include <linux/cpufreq.h>
11#include <linux/sched.h>
12#include <linux/sched/loadavg.h>
13#include <linux/module.h>
14#include <linux/timer.h>
15#include <linux/workqueue.h>
16#include <linux/atomic.h>
17#include <asm/machdep.h>
18#include <asm/spu.h>
19
20#define POLL_TIME	100000		/* in ��s */
21#define EXP		753		/* exp(-1) in fixed-point */
22
23struct spu_gov_info_struct {
24	unsigned long busy_spus;	/* fixed-point */
25	struct cpufreq_policy *policy;
26	struct delayed_work work;
27	unsigned int poll_int;		/* ��s */
28};
29static DEFINE_PER_CPU(struct spu_gov_info_struct, spu_gov_info);
30
31static int calc_freq(struct spu_gov_info_struct *info)
32{
33	int cpu;
34	int busy_spus;
35
36	cpu = info->policy->cpu;
37	busy_spus = atomic_read(&cbe_spu_info[cpu_to_node(cpu)].busy_spus);
38
39	info->busy_spus = calc_load(info->busy_spus, EXP, busy_spus * FIXED_1);
40	pr_debug("cpu %d: busy_spus=%d, info->busy_spus=%ld\n",
41			cpu, busy_spus, info->busy_spus);
42
43	return info->policy->max * info->busy_spus / FIXED_1;
44}
45
46static void spu_gov_work(struct work_struct *work)
47{
48	struct spu_gov_info_struct *info;
49	int delay;
50	unsigned long target_freq;
51
52	info = container_of(work, struct spu_gov_info_struct, work.work);
53
54	/* after cancel_delayed_work_sync we unset info->policy */
55	BUG_ON(info->policy == NULL);
56
57	target_freq = calc_freq(info);
58	__cpufreq_driver_target(info->policy, target_freq, CPUFREQ_RELATION_H);
59
60	delay = usecs_to_jiffies(info->poll_int);
61	schedule_delayed_work_on(info->policy->cpu, &info->work, delay);
62}
63
64static void spu_gov_init_work(struct spu_gov_info_struct *info)
65{
66	int delay = usecs_to_jiffies(info->poll_int);
67	INIT_DEFERRABLE_WORK(&info->work, spu_gov_work);
68	schedule_delayed_work_on(info->policy->cpu, &info->work, delay);
69}
70
71static void spu_gov_cancel_work(struct spu_gov_info_struct *info)
72{
73	cancel_delayed_work_sync(&info->work);
74}
75
76static int spu_gov_start(struct cpufreq_policy *policy)
77{
78	unsigned int cpu = policy->cpu;
79	struct spu_gov_info_struct *info = &per_cpu(spu_gov_info, cpu);
80	struct spu_gov_info_struct *affected_info;
81	int i;
82
83	if (!cpu_online(cpu)) {
84		printk(KERN_ERR "cpu %d is not online\n", cpu);
85		return -EINVAL;
86	}
87
88	if (!policy->cur) {
89		printk(KERN_ERR "no cpu specified in policy\n");
90		return -EINVAL;
91	}
92
93	/* initialize spu_gov_info for all affected cpus */
94	for_each_cpu(i, policy->cpus) {
95		affected_info = &per_cpu(spu_gov_info, i);
96		affected_info->policy = policy;
97	}
98
99	info->poll_int = POLL_TIME;
100
101	/* setup timer */
102	spu_gov_init_work(info);
103
104	return 0;
105}
106
107static void spu_gov_stop(struct cpufreq_policy *policy)
108{
109	unsigned int cpu = policy->cpu;
110	struct spu_gov_info_struct *info = &per_cpu(spu_gov_info, cpu);
111	int i;
112
113	/* cancel timer */
114	spu_gov_cancel_work(info);
115
116	/* clean spu_gov_info for all affected cpus */
117	for_each_cpu (i, policy->cpus) {
118		info = &per_cpu(spu_gov_info, i);
119		info->policy = NULL;
120	}
121}
122
123static struct cpufreq_governor spu_governor = {
124	.name = "spudemand",
125	.start = spu_gov_start,
126	.stop = spu_gov_stop,
127	.owner = THIS_MODULE,
128};
129cpufreq_governor_init(spu_governor);
130cpufreq_governor_exit(spu_governor);
131
132MODULE_LICENSE("GPL");
133MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");
134