diff options
Diffstat (limited to 'arch/powerpc/platforms/cell/cpufreq_spudemand.c')
| -rw-r--r-- | arch/powerpc/platforms/cell/cpufreq_spudemand.c | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/cell/cpufreq_spudemand.c b/arch/powerpc/platforms/cell/cpufreq_spudemand.c new file mode 100644 index 000000000..ca7849e11 --- /dev/null +++ b/arch/powerpc/platforms/cell/cpufreq_spudemand.c @@ -0,0 +1,133 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * spu aware cpufreq governor for the cell processor + * + * © Copyright IBM Corporation 2006-2008 + * + * Author: Christian Krafft <krafft@de.ibm.com> + */ + +#include <linux/cpufreq.h> +#include <linux/sched.h> +#include <linux/sched/loadavg.h> +#include <linux/module.h> +#include <linux/timer.h> +#include <linux/workqueue.h> +#include <linux/atomic.h> +#include <asm/machdep.h> +#include <asm/spu.h> + +#define POLL_TIME 100000 /* in µs */ +#define EXP 753 /* exp(-1) in fixed-point */ + +struct spu_gov_info_struct { + unsigned long busy_spus; /* fixed-point */ + struct cpufreq_policy *policy; + struct delayed_work work; + unsigned int poll_int; /* µs */ +}; +static DEFINE_PER_CPU(struct spu_gov_info_struct, spu_gov_info); + +static int calc_freq(struct spu_gov_info_struct *info) +{ + int cpu; + int busy_spus; + + cpu = info->policy->cpu; + busy_spus = atomic_read(&cbe_spu_info[cpu_to_node(cpu)].busy_spus); + + info->busy_spus = calc_load(info->busy_spus, EXP, busy_spus * FIXED_1); + pr_debug("cpu %d: busy_spus=%d, info->busy_spus=%ld\n", + cpu, busy_spus, info->busy_spus); + + return info->policy->max * info->busy_spus / FIXED_1; +} + +static void spu_gov_work(struct work_struct *work) +{ + struct spu_gov_info_struct *info; + int delay; + unsigned long target_freq; + + info = container_of(work, struct spu_gov_info_struct, work.work); + + /* after cancel_delayed_work_sync we unset info->policy */ + BUG_ON(info->policy == NULL); + + target_freq = calc_freq(info); + __cpufreq_driver_target(info->policy, target_freq, CPUFREQ_RELATION_H); + + delay = usecs_to_jiffies(info->poll_int); + schedule_delayed_work_on(info->policy->cpu, &info->work, delay); +} + +static void spu_gov_init_work(struct spu_gov_info_struct *info) +{ + int delay = usecs_to_jiffies(info->poll_int); + INIT_DEFERRABLE_WORK(&info->work, spu_gov_work); + schedule_delayed_work_on(info->policy->cpu, &info->work, delay); +} + +static void spu_gov_cancel_work(struct spu_gov_info_struct *info) +{ + cancel_delayed_work_sync(&info->work); +} + +static int spu_gov_start(struct cpufreq_policy *policy) +{ + unsigned int cpu = policy->cpu; + struct spu_gov_info_struct *info = &per_cpu(spu_gov_info, cpu); + struct spu_gov_info_struct *affected_info; + int i; + + if (!cpu_online(cpu)) { + printk(KERN_ERR "cpu %d is not online\n", cpu); + return -EINVAL; + } + + if (!policy->cur) { + printk(KERN_ERR "no cpu specified in policy\n"); + return -EINVAL; + } + + /* initialize spu_gov_info for all affected cpus */ + for_each_cpu(i, policy->cpus) { + affected_info = &per_cpu(spu_gov_info, i); + affected_info->policy = policy; + } + + info->poll_int = POLL_TIME; + + /* setup timer */ + spu_gov_init_work(info); + + return 0; +} + +static void spu_gov_stop(struct cpufreq_policy *policy) +{ + unsigned int cpu = policy->cpu; + struct spu_gov_info_struct *info = &per_cpu(spu_gov_info, cpu); + int i; + + /* cancel timer */ + spu_gov_cancel_work(info); + + /* clean spu_gov_info for all affected cpus */ + for_each_cpu (i, policy->cpus) { + info = &per_cpu(spu_gov_info, i); + info->policy = NULL; + } +} + +static struct cpufreq_governor spu_governor = { + .name = "spudemand", + .start = spu_gov_start, + .stop = spu_gov_stop, + .owner = THIS_MODULE, +}; +cpufreq_governor_init(spu_governor); +cpufreq_governor_exit(spu_governor); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>"); |