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[linux-2.6/next.git] / arch / powerpc / platforms / cell / cpufreq_spudemand.c
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1 /*
2 * spu aware cpufreq governor for the cell processor
4 * © Copyright IBM Corporation 2006-2008
6 * Author: Christian Krafft <krafft@de.ibm.com>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2, or (at your option)
11 * any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23 #include <linux/cpufreq.h>
24 #include <linux/sched.h>
25 #include <linux/timer.h>
26 #include <linux/workqueue.h>
27 #include <asm/atomic.h>
28 #include <asm/machdep.h>
29 #include <asm/spu.h>
31 #define POLL_TIME 100000 /* in µs */
32 #define EXP 753 /* exp(-1) in fixed-point */
34 struct spu_gov_info_struct {
35 unsigned long busy_spus; /* fixed-point */
36 struct cpufreq_policy *policy;
37 struct delayed_work work;
38 unsigned int poll_int; /* µs */
40 static DEFINE_PER_CPU(struct spu_gov_info_struct, spu_gov_info);
42 static int calc_freq(struct spu_gov_info_struct *info)
44 int cpu;
45 int busy_spus;
47 cpu = info->policy->cpu;
48 busy_spus = atomic_read(&cbe_spu_info[cpu_to_node(cpu)].busy_spus);
50 CALC_LOAD(info->busy_spus, EXP, busy_spus * FIXED_1);
51 pr_debug("cpu %d: busy_spus=%d, info->busy_spus=%ld\n",
52 cpu, busy_spus, info->busy_spus);
54 return info->policy->max * info->busy_spus / FIXED_1;
57 static void spu_gov_work(struct work_struct *work)
59 struct spu_gov_info_struct *info;
60 int delay;
61 unsigned long target_freq;
63 info = container_of(work, struct spu_gov_info_struct, work.work);
65 /* after cancel_delayed_work_sync we unset info->policy */
66 BUG_ON(info->policy == NULL);
68 target_freq = calc_freq(info);
69 __cpufreq_driver_target(info->policy, target_freq, CPUFREQ_RELATION_H);
71 delay = usecs_to_jiffies(info->poll_int);
72 schedule_delayed_work_on(info->policy->cpu, &info->work, delay);
75 static void spu_gov_init_work(struct spu_gov_info_struct *info)
77 int delay = usecs_to_jiffies(info->poll_int);
78 INIT_DELAYED_WORK_DEFERRABLE(&info->work, spu_gov_work);
79 schedule_delayed_work_on(info->policy->cpu, &info->work, delay);
82 static void spu_gov_cancel_work(struct spu_gov_info_struct *info)
84 cancel_delayed_work_sync(&info->work);
87 static int spu_gov_govern(struct cpufreq_policy *policy, unsigned int event)
89 unsigned int cpu = policy->cpu;
90 struct spu_gov_info_struct *info, *affected_info;
91 int i;
92 int ret = 0;
94 info = &per_cpu(spu_gov_info, cpu);
96 switch (event) {
97 case CPUFREQ_GOV_START:
98 if (!cpu_online(cpu)) {
99 printk(KERN_ERR "cpu %d is not online\n", cpu);
100 ret = -EINVAL;
101 break;
104 if (!policy->cur) {
105 printk(KERN_ERR "no cpu specified in policy\n");
106 ret = -EINVAL;
107 break;
110 /* initialize spu_gov_info for all affected cpus */
111 for_each_cpu(i, policy->cpus) {
112 affected_info = &per_cpu(spu_gov_info, i);
113 affected_info->policy = policy;
116 info->poll_int = POLL_TIME;
118 /* setup timer */
119 spu_gov_init_work(info);
121 break;
123 case CPUFREQ_GOV_STOP:
124 /* cancel timer */
125 spu_gov_cancel_work(info);
127 /* clean spu_gov_info for all affected cpus */
128 for_each_cpu (i, policy->cpus) {
129 info = &per_cpu(spu_gov_info, i);
130 info->policy = NULL;
133 break;
136 return ret;
139 static struct cpufreq_governor spu_governor = {
140 .name = "spudemand",
141 .governor = spu_gov_govern,
142 .owner = THIS_MODULE,
146 * module init and destoy
149 static int __init spu_gov_init(void)
151 int ret;
153 ret = cpufreq_register_governor(&spu_governor);
154 if (ret)
155 printk(KERN_ERR "registration of governor failed\n");
156 return ret;
159 static void __exit spu_gov_exit(void)
161 cpufreq_unregister_governor(&spu_governor);
165 module_init(spu_gov_init);
166 module_exit(spu_gov_exit);
168 MODULE_LICENSE("GPL");
169 MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");