diff options
Diffstat (limited to 'drivers/cpufreq/cpufreq_userspace.c')
| -rw-r--r-- | drivers/cpufreq/cpufreq_userspace.c | 222 |
1 files changed, 222 insertions, 0 deletions
diff --git a/drivers/cpufreq/cpufreq_userspace.c b/drivers/cpufreq/cpufreq_userspace.c new file mode 100644 index 00000000..bedac1aa --- /dev/null +++ b/drivers/cpufreq/cpufreq_userspace.c @@ -0,0 +1,222 @@ + +/* + * 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; + + 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: + 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); |