drivers/cpufreq/cpufreq_userspace.c

   1
   2 /*
   3  *  linux/drivers/cpufreq/cpufreq_userspace.c
   4  *
   5  *  Copyright (C)  2001 Russell King
   6  *            (C)  2002 - 2004 Dominik Brodowski <linux@brodo.de>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  *
  12  */
  13
  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/cpu.h>
  22 #include <linux/types.h>
  23 #include <linux/fs.h>
  24 #include <linux/sysfs.h>
  25 #include <linux/mutex.h>
  26
  27 #include <asm/uaccess.h>
  28
  29
  30 /**
  31  * A few values needed by the userspace governor
  32  */
  33 static unsigned int     cpu_max_freq[NR_CPUS];
  34 static unsigned int     cpu_min_freq[NR_CPUS];
  35 static unsigned int     cpu_cur_freq[NR_CPUS]; /* current CPU freq */
  36 static unsigned int     cpu_set_freq[NR_CPUS]; /* CPU freq desired by userspace */
  37 static unsigned int     cpu_is_managed[NR_CPUS];
  38
  39 static DEFINE_MUTEX     (userspace_mutex);
  40
  41 #define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_GOVERNOR, "userspace", msg)
  42
  43 /* keep track of frequency transitions */
  44 static int
  45 userspace_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
  46                        void *data)
  47 {
  48         struct cpufreq_freqs *freq = data;
  49
  50         dprintk("saving cpu_cur_freq of cpu %u to be %u kHz\n", freq->cpu, freq->new);
  51         cpu_cur_freq[freq->cpu] = freq->new;
  52
  53         return 0;
  54 }
  55
  56 static struct notifier_block userspace_cpufreq_notifier_block = {
  57         .notifier_call  = userspace_cpufreq_notifier
  58 };
  59
  60
  61 /**
  62  * cpufreq_set - set the CPU frequency
  63  * @freq: target frequency in kHz
  64  * @cpu: CPU for which the frequency is to be set
  65  *
  66  * Sets the CPU frequency to freq.
  67  */
  68 static int cpufreq_set(unsigned int freq, struct cpufreq_policy *policy)
  69 {
  70         int ret = -EINVAL;
  71
  72         dprintk("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);
  73
  74         mutex_lock(&userspace_mutex);
  75         if (!cpu_is_managed[policy->cpu])
  76                 goto err;
  77
  78         cpu_set_freq[policy->cpu] = freq;
  79
  80         if (freq < cpu_min_freq[policy->cpu])
  81                 freq = cpu_min_freq[policy->cpu];
  82         if (freq > cpu_max_freq[policy->cpu])
  83                 freq = cpu_max_freq[policy->cpu];
  84
  85         /*
  86          * We're safe from concurrent calls to ->target() here
  87          * as we hold the userspace_mutex lock. If we were calling
  88          * cpufreq_driver_target, a deadlock situation might occur:
  89          * A: cpufreq_set (lock userspace_mutex) -> cpufreq_driver_target(lock policy->lock)
  90          * B: cpufreq_set_policy(lock policy->lock) -> __cpufreq_governor -> cpufreq_governor_userspace (lock userspace_mutex)
  91          */
  92         ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
  93
  94  err:
  95         mutex_unlock(&userspace_mutex);
  96         return ret;
  97 }
  98
  99
 100 /************************** sysfs interface ************************/
 101 static ssize_t show_speed (struct cpufreq_policy *policy, char *buf)
 102 {
 103         return sprintf (buf, "%u\n", cpu_cur_freq[policy->cpu]);
 104 }
 105
 106 static ssize_t
 107 store_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);
 117
 118         return count;
 119 }
 120
 121 static 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
 128 static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
 129                                    unsigned int event)
 130 {
 131         unsigned int cpu = policy->cpu;
 132         int rc = 0;
 133
 134         switch (event) {
 135         case CPUFREQ_GOV_START:
 136                 if (!cpu_online(cpu))
 137                         return -EINVAL;
 138                 BUG_ON(!policy->cur);
 139                 mutex_lock(&userspace_mutex);
 140                 rc = sysfs_create_file (&policy->kobj,
 141                                         &freq_attr_scaling_setspeed.attr);
 142                 if (rc)
 143                         goto start_out;
 144
 145                 cpu_is_managed[cpu] = 1;
 146                 cpu_min_freq[cpu] = policy->min;
 147                 cpu_max_freq[cpu] = policy->max;
 148                 cpu_cur_freq[cpu] = policy->cur;
 149                 cpu_set_freq[cpu] = policy->cur;
 150                 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]);
 151 start_out:
 152                 mutex_unlock(&userspace_mutex);
 153                 break;
 154         case CPUFREQ_GOV_STOP:
 155                 mutex_lock(&userspace_mutex);
 156                 cpu_is_managed[cpu] = 0;
 157                 cpu_min_freq[cpu] = 0;
 158                 cpu_max_freq[cpu] = 0;
 159                 cpu_set_freq[cpu] = 0;
 160                 sysfs_remove_file (&policy->kobj, &freq_attr_scaling_setspeed.attr);
 161                 dprintk("managing cpu %u stopped\n", cpu);
 162                 mutex_unlock(&userspace_mutex);
 163                 break;
 164         case CPUFREQ_GOV_LIMITS:
 165                 mutex_lock(&userspace_mutex);
 166                 dprintk("limit event for cpu %u: %u - %u kHz,"
 167                         "currently %u kHz, last set to %u kHz\n",
 168                         cpu, policy->min, policy->max,
 169                         cpu_cur_freq[cpu], cpu_set_freq[cpu]);
 170                 if (policy->max < cpu_set_freq[cpu]) {
 171                         __cpufreq_driver_target(policy, policy->max,
 172                                                 CPUFREQ_RELATION_H);
 173                 }
 174                 else if (policy->min > cpu_set_freq[cpu]) {
 175                         __cpufreq_driver_target(policy, policy->min,
 176                                                 CPUFREQ_RELATION_L);
 177                 }
 178                 else {
 179                         __cpufreq_driver_target(policy, cpu_set_freq[cpu],
 180                                                 CPUFREQ_RELATION_L);
 181                 }
 182                 cpu_min_freq[cpu] = policy->min;
 183                 cpu_max_freq[cpu] = policy->max;
 184                 cpu_cur_freq[cpu] = policy->cur;
 185                 mutex_unlock(&userspace_mutex);
 186                 break;
 187         }
 188         return rc;
 189 }
 190
 191
 192 struct cpufreq_governor cpufreq_gov_userspace = {
 193         .name           = "userspace",
 194         .governor       = cpufreq_governor_userspace,
 195         .owner          = THIS_MODULE,
 196 };
 197 EXPORT_SYMBOL(cpufreq_gov_userspace);
 198
 199 static int __init cpufreq_gov_userspace_init(void)
 200 {
 201         cpufreq_register_notifier(&userspace_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER);
 202         return cpufreq_register_governor(&cpufreq_gov_userspace);
 203 }
 204
 205
 206 static void __exit cpufreq_gov_userspace_exit(void)
 207 {
 208         cpufreq_unregister_governor(&cpufreq_gov_userspace);
 209         cpufreq_unregister_notifier(&userspace_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER);
 210 }
 211
 212
 213 MODULE_AUTHOR ("Dominik Brodowski <linux@brodo.de>, Russell King <rmk@arm.linux.org.uk>");
 214 MODULE_DESCRIPTION ("CPUfreq policy governor 'userspace'");
 215 MODULE_LICENSE ("GPL");
 216
 217 fs_initcall(cpufreq_gov_userspace_init);
 218 module_exit(cpufreq_gov_userspace_exit);