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