LXR linux-bk/drivers/cpufreq/cpufreq

   1/*
   2 *  linux/drivers/cpufreq/cpufreq_userspace.c
   3 *
   4 *  Copyright (C)  2001 Russell King
   5 *            (C)  2002 - 2004 Dominik Brodowski <linux@brodo.de>
   6 *
   7 * This program is free software; you can redistribute it and/or modify
   8 * it under the terms of the GNU General Public License version 2 as
   9 * published by the Free Software Foundation.
  10 *
  11 */
  12
  13#include <linux/config.h>
  14#include <linux/kernel.h>
  15#include <linux/module.h>
  16#include <linux/smp.h>
  17#include <linux/init.h>
  18#include <linux/spinlock.h>
  19#include <linux/interrupt.h>
  20#include <linux/cpufreq.h>
  21#include <linux/types.h>
  22#include <linux/fs.h>
  23#include <linux/sysfs.h>
  24
  25#include <asm/uaccess.h>
  26
  27
  28/**
  29 * A few values needed by the userspace governor
  30 */
  31static unsigned int     cpu_max_freq[NR_CPUS];
  32static unsigned int     cpu_min_freq[NR_CPUS];
  33static unsigned int     cpu_cur_freq[NR_CPUS]; /* current CPU freq */
  34static unsigned int     cpu_set_freq[NR_CPUS]; /* CPU freq desired by userspace */
  35static unsigned int     cpu_is_managed[NR_CPUS];
  36static struct cpufreq_policy current_policy[NR_CPUS];
  37
  38static DECLARE_MUTEX    (userspace_sem); 
  39
  40#define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_GOVERNOR, "userspace", msg)
  41
  42/* keep track of frequency transitions */
  43static int 
  44userspace_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
  45                       void *data)
  46{
  47        struct cpufreq_freqs *freq = data;
  48
  49        dprintk("saving cpu_cur_freq of cpu %u to be %u kHz\n", freq->cpu, freq->new);
  50        cpu_cur_freq[freq->cpu] = freq->new;
  51
  52        return 0;
  53}
  54
  55static struct notifier_block userspace_cpufreq_notifier_block = {
  56        .notifier_call  = userspace_cpufreq_notifier
  57};
  58
  59
  60/** 
  61 * cpufreq_set - set the CPU frequency
  62 * @freq: target frequency in kHz
  63 * @cpu: CPU for which the frequency is to be set
  64 *
  65 * Sets the CPU frequency to freq.
  66 */
  67static int cpufreq_set(unsigned int freq, unsigned int cpu)
  68{
  69        int ret = -EINVAL;
  70
  71        dprintk("cpufreq_set for cpu %u, freq %u kHz\n", cpu, freq);
  72
  73        down(&userspace_sem);
  74        if (!cpu_is_managed[cpu])
  75                goto err;
  76
  77        cpu_set_freq[cpu] = freq;
  78
  79        if (freq < cpu_min_freq[cpu])
  80                freq = cpu_min_freq[cpu];
  81        if (freq > cpu_max_freq[cpu])
  82                freq = cpu_max_freq[cpu];
  83
  84        /*
  85         * We're safe from concurrent calls to ->target() here
  86         * as we hold the userspace_sem lock. If we were calling
  87         * cpufreq_driver_target, a deadlock situation might occur:
  88         * A: cpufreq_set (lock userspace_sem) -> cpufreq_driver_target(lock policy->lock)
  89         * B: cpufreq_set_policy(lock policy->lock) -> __cpufreq_governor -> cpufreq_governor_userspace (lock userspace_sem)
  90         */
  91        ret = __cpufreq_driver_target(&current_policy[cpu], freq, 
  92              CPUFREQ_RELATION_L);
  93
  94 err:
  95        up(&userspace_sem);
  96        return ret;
  97}
  98
  99
 100/************************** sysfs interface ************************/
 101static ssize_t show_speed (struct cpufreq_policy *policy, char *buf)
 102{
 103        return sprintf (buf, "%u\n", cpu_cur_freq[policy->cpu]);
 104}
 105
 106static ssize_t 
 107store_speed (struct cpufreq_policy *policy, const char *buf, size_t count) 
 108{
 109        unsigned int freq = 0;
 110        unsigned int ret;
 111
 112        ret = sscanf (buf, "%u", &freq);
 113        if (ret != 1)
 114                return -EINVAL;
 115
 116        cpufreq_set(freq, policy->cpu);
 117
 118        return count;
 119}
 120
 121static struct freq_attr freq_attr_scaling_setspeed = 
 122{
 123        .attr = { .name = "scaling_setspeed", .mode = 0644, .owner = THIS_MODULE },
 124        .show = show_speed,
 125        .store = store_speed,
 126};
 127
 128static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
 129                                   unsigned int event)
 130{
 131        unsigned int cpu = policy->cpu;
 132        switch (event) {
 133        case CPUFREQ_GOV_START:
 134                if (!cpu_online(cpu))
 135                        return -EINVAL;
 136                BUG_ON(!policy->cur);
 137                down(&userspace_sem);
 138                cpu_is_managed[cpu] = 1;                
 139                cpu_min_freq[cpu] = policy->min;
 140                cpu_max_freq[cpu] = policy->max;
 141                cpu_cur_freq[cpu] = policy->cur;
 142                cpu_set_freq[cpu] = policy->cur;
 143                sysfs_create_file (&policy->kobj, &freq_attr_scaling_setspeed.attr);
 144                memcpy (&current_policy[cpu], policy, sizeof(struct cpufreq_policy));
 145                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]);
 146                up(&userspace_sem);
 147                break;
 148        case CPUFREQ_GOV_STOP:
 149                down(&userspace_sem);
 150                cpu_is_managed[cpu] = 0;
 151                cpu_min_freq[cpu] = 0;
 152                cpu_max_freq[cpu] = 0;
 153                cpu_set_freq[cpu] = 0;
 154                sysfs_remove_file (&policy->kobj, &freq_attr_scaling_setspeed.attr);
 155                dprintk("managing cpu %u stopped\n", cpu);
 156                up(&userspace_sem);
 157                break;
 158        case CPUFREQ_GOV_LIMITS:
 159                down(&userspace_sem);
 160                cpu_min_freq[cpu] = policy->min;
 161                cpu_max_freq[cpu] = policy->max;
 162                dprintk("limit event for cpu %u: %u - %u kHz, currently %u kHz, last set to %u kHz\n", cpu, cpu_min_freq[cpu], cpu_max_freq[cpu], cpu_cur_freq[cpu], cpu_set_freq[cpu]);
 163                if (policy->max < cpu_set_freq[cpu]) {
 164                        __cpufreq_driver_target(&current_policy[cpu], policy->max, 
 165                              CPUFREQ_RELATION_H);
 166                } else if (policy->min > cpu_set_freq[cpu]) {
 167                        __cpufreq_driver_target(&current_policy[cpu], policy->min, 
 168                              CPUFREQ_RELATION_L);
 169                } else {
 170                        __cpufreq_driver_target(&current_policy[cpu], cpu_set_freq[cpu],
 171                              CPUFREQ_RELATION_L);
 172                }
 173                memcpy (&current_policy[cpu], policy, sizeof(struct cpufreq_policy));
 174                up(&userspace_sem);
 175                break;
 176        }
 177        return 0;
 178}
 179
 180
 181struct cpufreq_governor cpufreq_gov_userspace = {
 182        .name           = "userspace",
 183        .governor       = cpufreq_governor_userspace,
 184        .owner          = THIS_MODULE,
 185};
 186EXPORT_SYMBOL(cpufreq_gov_userspace);
 187
 188static int __init cpufreq_gov_userspace_init(void)
 189{
 190        cpufreq_register_notifier(&userspace_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER);
 191        return cpufreq_register_governor(&cpufreq_gov_userspace);
 192}
 193
 194
 195static void __exit cpufreq_gov_userspace_exit(void)
 196{
 197        cpufreq_unregister_governor(&cpufreq_gov_userspace);
 198        cpufreq_unregister_notifier(&userspace_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER);
 199}
 200
 201
 202MODULE_AUTHOR ("Dominik Brodowski <linux@brodo.de>, Russell King <rmk@arm.linux.org.uk>");
 203MODULE_DESCRIPTION ("CPUfreq policy governor 'userspace'");
 204MODULE_LICENSE ("GPL");
 205
 206fs_initcall(cpufreq_gov_userspace_init);
 207module_exit(cpufreq_gov_userspace_exit);
 208