| |
| /* |
| * 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> |
| |
| /** |
| * 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; |
| |
| 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: |
| if (!cpu_online(cpu)) |
| return -EINVAL; |
| 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); |