/* * 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. * */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #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> /** * A few values needed by the userspace governor */ static DEFINE_PER_CPU(unsigned int, cpu_max_freq); static DEFINE_PER_CPU(unsigned int, cpu_min_freq); static DEFINE_PER_CPU(unsigned int, cpu_cur_freq); /* current CPU freq */ static DEFINE_PER_CPU(unsigned int, cpu_set_freq); /* CPU freq desired by userspace */ static DEFINE_PER_CPU(unsigned int, cpu_is_managed); static DEFINE_MUTEX(userspace_mutex); static int cpus_using_userspace_governor; /* keep track of frequency transitions */ static int userspace_cpufreq_notifier(struct notifier_block *nb, unsigned long val, void *data) { struct cpufreq_freqs *freq = data; if (!per_cpu(cpu_is_managed, freq->cpu)) return 0; if (val == CPUFREQ_POSTCHANGE) { pr_debug("saving cpu_cur_freq of cpu %u to be %u kHz\n", freq->cpu, freq->new); per_cpu(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 * @policy: pointer to policy struct where freq is being set * @freq: target frequency in kHz * * Sets the CPU frequency to freq. */ static int cpufreq_set(struct cpufreq_policy *policy, unsigned int freq) { int ret = -EINVAL; pr_debug("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq); mutex_lock(&userspace_mutex); if (!per_cpu(cpu_is_managed, policy->cpu)) goto err; per_cpu(cpu_set_freq, policy->cpu) = freq; if (freq < per_cpu(cpu_min_freq, policy->cpu)) freq = per_cpu(cpu_min_freq, policy->cpu); if (freq > per_cpu(cpu_max_freq, policy->cpu)) freq = per_cpu(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; } static ssize_t show_speed(struct cpufreq_policy *policy, char *buf) { return sprintf(buf, "%u\n", per_cpu(cpu_cur_freq, policy->cpu)); } 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: BUG_ON(!policy->cur); mutex_lock(&userspace_mutex); if (cpus_using_userspace_governor == 0) { cpufreq_register_notifier( &userspace_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER); } cpus_using_userspace_governor++; per_cpu(cpu_is_managed, cpu) = 1; per_cpu(cpu_min_freq, cpu) = policy->min; per_cpu(cpu_max_freq, cpu) = policy->max; per_cpu(cpu_cur_freq, cpu) = policy->cur; per_cpu(cpu_set_freq, cpu) = policy->cur; pr_debug("managing cpu %u started " "(%u - %u kHz, currently %u kHz)\n", cpu, per_cpu(cpu_min_freq, cpu), per_cpu(cpu_max_freq, cpu), per_cpu(cpu_cur_freq, cpu)); mutex_unlock(&userspace_mutex); break; case CPUFREQ_GOV_STOP: mutex_lock(&userspace_mutex); cpus_using_userspace_governor--; if (cpus_using_userspace_governor == 0) { cpufreq_unregister_notifier( &userspace_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER); } per_cpu(cpu_is_managed, cpu) = 0; per_cpu(cpu_min_freq, cpu) = 0; per_cpu(cpu_max_freq, cpu) = 0; per_cpu(cpu_set_freq, cpu) = 0; pr_debug("managing cpu %u stopped\n", cpu); mutex_unlock(&userspace_mutex); break; case CPUFREQ_GOV_LIMITS: mutex_lock(&userspace_mutex); pr_debug("limit event for cpu %u: %u - %u kHz, " "currently %u kHz, last set to %u kHz\n", cpu, policy->min, policy->max, per_cpu(cpu_cur_freq, cpu), per_cpu(cpu_set_freq, cpu)); if (policy->max < per_cpu(cpu_set_freq, cpu)) { __cpufreq_driver_target(policy, policy->max, CPUFREQ_RELATION_H); } else if (policy->min > per_cpu(cpu_set_freq, cpu)) { __cpufreq_driver_target(policy, policy->min, CPUFREQ_RELATION_L); } else { __cpufreq_driver_target(policy, per_cpu(cpu_set_freq, cpu), CPUFREQ_RELATION_L); } per_cpu(cpu_min_freq, cpu) = policy->min; per_cpu(cpu_max_freq, cpu) = policy->max; per_cpu(cpu_cur_freq, cpu) = policy->cur; mutex_unlock(&userspace_mutex); break; } return rc; } #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE static #endif struct cpufreq_governor cpufreq_gov_userspace = { .name = "userspace", .governor = cpufreq_governor_userspace, .store_setspeed = cpufreq_set, .show_setspeed = show_speed, .owner = THIS_MODULE, }; static int __init cpufreq_gov_userspace_init(void) { return cpufreq_register_governor(&cpufreq_gov_userspace); } static void __exit cpufreq_gov_userspace_exit(void) { cpufreq_unregister_governor(&cpufreq_gov_userspace); } MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>, " "Russell King <rmk@arm.linux.org.uk>"); MODULE_DESCRIPTION("CPUfreq policy governor 'userspace'"); MODULE_LICENSE("GPL"); #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE fs_initcall(cpufreq_gov_userspace_init); #else module_init(cpufreq_gov_userspace_init); #endif module_exit(cpufreq_gov_userspace_exit);