1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-or-later
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * spu aware cpufreq governor for the cell processor
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * © Copyright IBM Corporation 2006-2008
6*4882a593Smuzhiyun *
7*4882a593Smuzhiyun * Author: Christian Krafft <krafft@de.ibm.com>
8*4882a593Smuzhiyun */
9*4882a593Smuzhiyun
10*4882a593Smuzhiyun #include <linux/cpufreq.h>
11*4882a593Smuzhiyun #include <linux/sched.h>
12*4882a593Smuzhiyun #include <linux/sched/loadavg.h>
13*4882a593Smuzhiyun #include <linux/module.h>
14*4882a593Smuzhiyun #include <linux/timer.h>
15*4882a593Smuzhiyun #include <linux/workqueue.h>
16*4882a593Smuzhiyun #include <linux/atomic.h>
17*4882a593Smuzhiyun #include <asm/machdep.h>
18*4882a593Smuzhiyun #include <asm/spu.h>
19*4882a593Smuzhiyun
20*4882a593Smuzhiyun #define POLL_TIME 100000 /* in µs */
21*4882a593Smuzhiyun #define EXP 753 /* exp(-1) in fixed-point */
22*4882a593Smuzhiyun
23*4882a593Smuzhiyun struct spu_gov_info_struct {
24*4882a593Smuzhiyun unsigned long busy_spus; /* fixed-point */
25*4882a593Smuzhiyun struct cpufreq_policy *policy;
26*4882a593Smuzhiyun struct delayed_work work;
27*4882a593Smuzhiyun unsigned int poll_int; /* µs */
28*4882a593Smuzhiyun };
29*4882a593Smuzhiyun static DEFINE_PER_CPU(struct spu_gov_info_struct, spu_gov_info);
30*4882a593Smuzhiyun
calc_freq(struct spu_gov_info_struct * info)31*4882a593Smuzhiyun static int calc_freq(struct spu_gov_info_struct *info)
32*4882a593Smuzhiyun {
33*4882a593Smuzhiyun int cpu;
34*4882a593Smuzhiyun int busy_spus;
35*4882a593Smuzhiyun
36*4882a593Smuzhiyun cpu = info->policy->cpu;
37*4882a593Smuzhiyun busy_spus = atomic_read(&cbe_spu_info[cpu_to_node(cpu)].busy_spus);
38*4882a593Smuzhiyun
39*4882a593Smuzhiyun info->busy_spus = calc_load(info->busy_spus, EXP, busy_spus * FIXED_1);
40*4882a593Smuzhiyun pr_debug("cpu %d: busy_spus=%d, info->busy_spus=%ld\n",
41*4882a593Smuzhiyun cpu, busy_spus, info->busy_spus);
42*4882a593Smuzhiyun
43*4882a593Smuzhiyun return info->policy->max * info->busy_spus / FIXED_1;
44*4882a593Smuzhiyun }
45*4882a593Smuzhiyun
spu_gov_work(struct work_struct * work)46*4882a593Smuzhiyun static void spu_gov_work(struct work_struct *work)
47*4882a593Smuzhiyun {
48*4882a593Smuzhiyun struct spu_gov_info_struct *info;
49*4882a593Smuzhiyun int delay;
50*4882a593Smuzhiyun unsigned long target_freq;
51*4882a593Smuzhiyun
52*4882a593Smuzhiyun info = container_of(work, struct spu_gov_info_struct, work.work);
53*4882a593Smuzhiyun
54*4882a593Smuzhiyun /* after cancel_delayed_work_sync we unset info->policy */
55*4882a593Smuzhiyun BUG_ON(info->policy == NULL);
56*4882a593Smuzhiyun
57*4882a593Smuzhiyun target_freq = calc_freq(info);
58*4882a593Smuzhiyun __cpufreq_driver_target(info->policy, target_freq, CPUFREQ_RELATION_H);
59*4882a593Smuzhiyun
60*4882a593Smuzhiyun delay = usecs_to_jiffies(info->poll_int);
61*4882a593Smuzhiyun schedule_delayed_work_on(info->policy->cpu, &info->work, delay);
62*4882a593Smuzhiyun }
63*4882a593Smuzhiyun
spu_gov_init_work(struct spu_gov_info_struct * info)64*4882a593Smuzhiyun static void spu_gov_init_work(struct spu_gov_info_struct *info)
65*4882a593Smuzhiyun {
66*4882a593Smuzhiyun int delay = usecs_to_jiffies(info->poll_int);
67*4882a593Smuzhiyun INIT_DEFERRABLE_WORK(&info->work, spu_gov_work);
68*4882a593Smuzhiyun schedule_delayed_work_on(info->policy->cpu, &info->work, delay);
69*4882a593Smuzhiyun }
70*4882a593Smuzhiyun
spu_gov_cancel_work(struct spu_gov_info_struct * info)71*4882a593Smuzhiyun static void spu_gov_cancel_work(struct spu_gov_info_struct *info)
72*4882a593Smuzhiyun {
73*4882a593Smuzhiyun cancel_delayed_work_sync(&info->work);
74*4882a593Smuzhiyun }
75*4882a593Smuzhiyun
spu_gov_start(struct cpufreq_policy * policy)76*4882a593Smuzhiyun static int spu_gov_start(struct cpufreq_policy *policy)
77*4882a593Smuzhiyun {
78*4882a593Smuzhiyun unsigned int cpu = policy->cpu;
79*4882a593Smuzhiyun struct spu_gov_info_struct *info = &per_cpu(spu_gov_info, cpu);
80*4882a593Smuzhiyun struct spu_gov_info_struct *affected_info;
81*4882a593Smuzhiyun int i;
82*4882a593Smuzhiyun
83*4882a593Smuzhiyun if (!cpu_online(cpu)) {
84*4882a593Smuzhiyun printk(KERN_ERR "cpu %d is not online\n", cpu);
85*4882a593Smuzhiyun return -EINVAL;
86*4882a593Smuzhiyun }
87*4882a593Smuzhiyun
88*4882a593Smuzhiyun if (!policy->cur) {
89*4882a593Smuzhiyun printk(KERN_ERR "no cpu specified in policy\n");
90*4882a593Smuzhiyun return -EINVAL;
91*4882a593Smuzhiyun }
92*4882a593Smuzhiyun
93*4882a593Smuzhiyun /* initialize spu_gov_info for all affected cpus */
94*4882a593Smuzhiyun for_each_cpu(i, policy->cpus) {
95*4882a593Smuzhiyun affected_info = &per_cpu(spu_gov_info, i);
96*4882a593Smuzhiyun affected_info->policy = policy;
97*4882a593Smuzhiyun }
98*4882a593Smuzhiyun
99*4882a593Smuzhiyun info->poll_int = POLL_TIME;
100*4882a593Smuzhiyun
101*4882a593Smuzhiyun /* setup timer */
102*4882a593Smuzhiyun spu_gov_init_work(info);
103*4882a593Smuzhiyun
104*4882a593Smuzhiyun return 0;
105*4882a593Smuzhiyun }
106*4882a593Smuzhiyun
spu_gov_stop(struct cpufreq_policy * policy)107*4882a593Smuzhiyun static void spu_gov_stop(struct cpufreq_policy *policy)
108*4882a593Smuzhiyun {
109*4882a593Smuzhiyun unsigned int cpu = policy->cpu;
110*4882a593Smuzhiyun struct spu_gov_info_struct *info = &per_cpu(spu_gov_info, cpu);
111*4882a593Smuzhiyun int i;
112*4882a593Smuzhiyun
113*4882a593Smuzhiyun /* cancel timer */
114*4882a593Smuzhiyun spu_gov_cancel_work(info);
115*4882a593Smuzhiyun
116*4882a593Smuzhiyun /* clean spu_gov_info for all affected cpus */
117*4882a593Smuzhiyun for_each_cpu (i, policy->cpus) {
118*4882a593Smuzhiyun info = &per_cpu(spu_gov_info, i);
119*4882a593Smuzhiyun info->policy = NULL;
120*4882a593Smuzhiyun }
121*4882a593Smuzhiyun }
122*4882a593Smuzhiyun
123*4882a593Smuzhiyun static struct cpufreq_governor spu_governor = {
124*4882a593Smuzhiyun .name = "spudemand",
125*4882a593Smuzhiyun .start = spu_gov_start,
126*4882a593Smuzhiyun .stop = spu_gov_stop,
127*4882a593Smuzhiyun .owner = THIS_MODULE,
128*4882a593Smuzhiyun };
129*4882a593Smuzhiyun cpufreq_governor_init(spu_governor);
130*4882a593Smuzhiyun cpufreq_governor_exit(spu_governor);
131*4882a593Smuzhiyun
132*4882a593Smuzhiyun MODULE_LICENSE("GPL");
133*4882a593Smuzhiyun MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");
134