236 lines
6.1 KiB
C
236 lines
6.1 KiB
C
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/*
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* linux/drivers/cpufreq/cpufreq_userspace.c
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*
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* Copyright (C) 2001 Russell King
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* (C) 2002 - 2004 Dominik Brodowski <linux@brodo.de>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/smp.h>
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#include <linux/init.h>
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#include <linux/spinlock.h>
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#include <linux/interrupt.h>
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#include <linux/cpufreq.h>
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#include <linux/cpu.h>
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#include <linux/types.h>
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#include <linux/fs.h>
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#include <linux/sysfs.h>
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#include <linux/mutex.h>
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#include <asm/uaccess.h>
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/**
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* A few values needed by the userspace governor
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*/
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static unsigned int cpu_max_freq[NR_CPUS];
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static unsigned int cpu_min_freq[NR_CPUS];
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static unsigned int cpu_cur_freq[NR_CPUS]; /* current CPU freq */
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static unsigned int cpu_set_freq[NR_CPUS]; /* CPU freq desired by userspace */
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static unsigned int cpu_is_managed[NR_CPUS];
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static DEFINE_MUTEX (userspace_mutex);
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static int cpus_using_userspace_governor;
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#define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_GOVERNOR, "userspace", msg)
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/* keep track of frequency transitions */
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static int
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userspace_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
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void *data)
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{
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struct cpufreq_freqs *freq = data;
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if (!cpu_is_managed[freq->cpu])
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return 0;
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dprintk("saving cpu_cur_freq of cpu %u to be %u kHz\n",
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freq->cpu, freq->new);
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cpu_cur_freq[freq->cpu] = freq->new;
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return 0;
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}
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static struct notifier_block userspace_cpufreq_notifier_block = {
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.notifier_call = userspace_cpufreq_notifier
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};
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/**
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* cpufreq_set - set the CPU frequency
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* @freq: target frequency in kHz
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* @cpu: CPU for which the frequency is to be set
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*
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* Sets the CPU frequency to freq.
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*/
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static int cpufreq_set(unsigned int freq, struct cpufreq_policy *policy)
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{
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int ret = -EINVAL;
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dprintk("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);
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mutex_lock(&userspace_mutex);
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if (!cpu_is_managed[policy->cpu])
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goto err;
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cpu_set_freq[policy->cpu] = freq;
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if (freq < cpu_min_freq[policy->cpu])
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freq = cpu_min_freq[policy->cpu];
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if (freq > cpu_max_freq[policy->cpu])
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freq = cpu_max_freq[policy->cpu];
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/*
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* We're safe from concurrent calls to ->target() here
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* as we hold the userspace_mutex lock. If we were calling
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* cpufreq_driver_target, a deadlock situation might occur:
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* A: cpufreq_set (lock userspace_mutex) -> cpufreq_driver_target(lock policy->lock)
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* B: cpufreq_set_policy(lock policy->lock) -> __cpufreq_governor -> cpufreq_governor_userspace (lock userspace_mutex)
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*/
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ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
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err:
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mutex_unlock(&userspace_mutex);
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return ret;
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}
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/************************** sysfs interface ************************/
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static ssize_t show_speed (struct cpufreq_policy *policy, char *buf)
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{
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return sprintf (buf, "%u\n", cpu_cur_freq[policy->cpu]);
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}
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static ssize_t
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store_speed (struct cpufreq_policy *policy, const char *buf, size_t count)
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{
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unsigned int freq = 0;
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unsigned int ret;
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ret = sscanf (buf, "%u", &freq);
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if (ret != 1)
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return -EINVAL;
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cpufreq_set(freq, policy);
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return count;
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}
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static struct freq_attr freq_attr_scaling_setspeed =
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{
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.attr = { .name = "scaling_setspeed", .mode = 0644 },
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.show = show_speed,
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.store = store_speed,
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};
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static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
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unsigned int event)
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{
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unsigned int cpu = policy->cpu;
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int rc = 0;
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switch (event) {
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case CPUFREQ_GOV_START:
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if (!cpu_online(cpu))
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return -EINVAL;
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BUG_ON(!policy->cur);
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mutex_lock(&userspace_mutex);
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rc = sysfs_create_file (&policy->kobj,
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&freq_attr_scaling_setspeed.attr);
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if (rc)
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goto start_out;
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if (cpus_using_userspace_governor == 0) {
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cpufreq_register_notifier(
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&userspace_cpufreq_notifier_block,
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CPUFREQ_TRANSITION_NOTIFIER);
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}
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cpus_using_userspace_governor++;
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cpu_is_managed[cpu] = 1;
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cpu_min_freq[cpu] = policy->min;
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cpu_max_freq[cpu] = policy->max;
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cpu_cur_freq[cpu] = policy->cur;
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cpu_set_freq[cpu] = policy->cur;
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dprintk("managing cpu %u started (%u - %u kHz, currently %u kHz)\n", cpu, cpu_min_freq[cpu], cpu_max_freq[cpu], cpu_cur_freq[cpu]);
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start_out:
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mutex_unlock(&userspace_mutex);
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break;
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case CPUFREQ_GOV_STOP:
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mutex_lock(&userspace_mutex);
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cpus_using_userspace_governor--;
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if (cpus_using_userspace_governor == 0) {
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cpufreq_unregister_notifier(
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&userspace_cpufreq_notifier_block,
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CPUFREQ_TRANSITION_NOTIFIER);
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}
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cpu_is_managed[cpu] = 0;
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cpu_min_freq[cpu] = 0;
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cpu_max_freq[cpu] = 0;
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cpu_set_freq[cpu] = 0;
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sysfs_remove_file (&policy->kobj, &freq_attr_scaling_setspeed.attr);
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dprintk("managing cpu %u stopped\n", cpu);
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mutex_unlock(&userspace_mutex);
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break;
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case CPUFREQ_GOV_LIMITS:
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mutex_lock(&userspace_mutex);
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dprintk("limit event for cpu %u: %u - %u kHz,"
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"currently %u kHz, last set to %u kHz\n",
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cpu, policy->min, policy->max,
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cpu_cur_freq[cpu], cpu_set_freq[cpu]);
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if (policy->max < cpu_set_freq[cpu]) {
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__cpufreq_driver_target(policy, policy->max,
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CPUFREQ_RELATION_H);
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}
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else if (policy->min > cpu_set_freq[cpu]) {
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__cpufreq_driver_target(policy, policy->min,
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CPUFREQ_RELATION_L);
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}
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else {
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__cpufreq_driver_target(policy, cpu_set_freq[cpu],
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CPUFREQ_RELATION_L);
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}
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cpu_min_freq[cpu] = policy->min;
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cpu_max_freq[cpu] = policy->max;
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cpu_cur_freq[cpu] = policy->cur;
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mutex_unlock(&userspace_mutex);
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break;
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}
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return rc;
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}
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struct cpufreq_governor cpufreq_gov_userspace = {
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.name = "userspace",
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.governor = cpufreq_governor_userspace,
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.owner = THIS_MODULE,
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};
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EXPORT_SYMBOL(cpufreq_gov_userspace);
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static int __init cpufreq_gov_userspace_init(void)
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{
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return cpufreq_register_governor(&cpufreq_gov_userspace);
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}
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static void __exit cpufreq_gov_userspace_exit(void)
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{
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cpufreq_unregister_governor(&cpufreq_gov_userspace);
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}
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MODULE_AUTHOR ("Dominik Brodowski <linux@brodo.de>, Russell King <rmk@arm.linux.org.uk>");
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MODULE_DESCRIPTION ("CPUfreq policy governor 'userspace'");
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MODULE_LICENSE ("GPL");
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fs_initcall(cpufreq_gov_userspace_init);
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module_exit(cpufreq_gov_userspace_exit);
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