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/types.h>
  22 #include <linux/fs.h>
  23 #include <linux/sysfs.h>
  24 #include <linux/mutex.h>
  25
  26 #include <asm/uaccess.h>
  27
  28
  29 /**
  30  * A few values needed by the userspace governor
  31  */
  32 static unsigned int     cpu_max_freq[NR_CPUS];
  33 static unsigned int     cpu_min_freq[NR_CPUS];
  34 static unsigned int     cpu_cur_freq[NR_CPUS]; /* current CPU freq */
  35 static unsigned int     cpu_set_freq[NR_CPUS]; /* CPU freq desired by userspace */
  36 static unsigned int     cpu_is_managed[NR_CPUS];
  37
  38 static DEFINE_MUTEX     (userspace_mutex);
  39
  40 #define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_GOVERNOR, "userspace", msg)
  41
  42 /* keep track of frequency transitions */
  43 static int
  44 userspace_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
  55 static 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  */
  67 static int cpufreq_set(unsigned int freq, struct cpufreq_policy *policy)
  68 {
  69         int ret = -EINVAL;
  70
  71         dprintk("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);
  72
  73         mutex_lock(&userspace_mutex);
  74         if (!cpu_is_managed[policy->cpu])
  75                 goto err;
  76
  77         cpu_set_freq[policy->cpu] = freq;
  78
  79         if (freq < cpu_min_freq[policy->cpu])
  80                 freq = cpu_min_freq[policy->cpu];
  81         if (freq > cpu_max_freq[policy->cpu])
  82                 freq = cpu_max_freq[policy->cpu];
  83
  84         /*
  85          * We're safe from concurrent calls to ->target() here
  86          * as we hold the userspace_mutex lock. If we were calling
  87          * cpufreq_driver_target, a deadlock situation might occur:
  88          * A: cpufreq_set (lock userspace_mutex) -> cpufreq_driver_target(lock policy->lock)
  89          * B: cpufreq_set_policy(lock policy->lock) -> __cpufreq_governor -> cpufreq_governor_userspace (lock userspace_mutex)
  90          */
  91         ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
  92
  93  err:
  94         mutex_unlock(&userspace_mutex);
  95         return ret;
  96 }
  97
  98
  99 /************************** sysfs interface ************************/
 100 static ssize_t show_speed (struct cpufreq_policy *policy, char *buf)
 101 {
 102         return sprintf (buf, "%u\n", cpu_cur_freq[policy->cpu]);
 103 }
 104
 105 static ssize_t
 106 store_speed (struct cpufreq_policy *policy, const char *buf, size_t count)
 107 {
 108         unsigned int freq = 0;
 109         unsigned int ret;
 110
 111         ret = sscanf (buf, "%u", &freq);
 112         if (ret != 1)
 113                 return -EINVAL;
 114
 115         cpufreq_set(freq, policy);
 116
 117         return count;
 118 }
 119
 120 static struct freq_attr freq_attr_scaling_setspeed =
 121 {
 122         .attr = { .name = "scaling_setspeed", .mode = 0644, .owner = THIS_MODULE },
 123         .show = show_speed,
 124         .store = store_speed,
 125 };
 126
 127 static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
 128                                    unsigned int event)
 129 {
 130         unsigned int cpu = policy->cpu;
 131         switch (event) {
 132         case CPUFREQ_GOV_START:
 133                 if (!cpu_online(cpu))
 134                         return -EINVAL;
 135                 BUG_ON(!policy->cur);
 136                 mutex_lock(&userspace_mutex);
 137                 cpu_is_managed[cpu] = 1;
 138                 cpu_min_freq[cpu] = policy->min;
 139                 cpu_max_freq[cpu] = policy->max;
 140                 cpu_cur_freq[cpu] = policy->cur;
 141                 cpu_set_freq[cpu] = policy->cur;
 142                 sysfs_create_file (&policy->kobj, &freq_attr_scaling_setspeed.attr);
 143                 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]);
 144                 mutex_unlock(&userspace_mutex);
 145                 break;
 146         case CPUFREQ_GOV_STOP:
 147                 mutex_lock(&userspace_mutex);
 148                 cpu_is_managed[cpu] = 0;
 149                 cpu_min_freq[cpu] = 0;
 150                 cpu_max_freq[cpu] = 0;
 151                 cpu_set_freq[cpu] = 0;
 152                 sysfs_remove_file (&policy->kobj, &freq_attr_scaling_setspeed.attr);
 153                 dprintk("managing cpu %u stopped\n", cpu);
 154                 mutex_unlock(&userspace_mutex);
 155                 break;
 156         case CPUFREQ_GOV_LIMITS:
 157                 mutex_lock(&userspace_mutex);
 158                 dprintk("limit event for cpu %u: %u - %u kHz,"
 159                         "currently %u kHz, last set to %u kHz\n",
 160                         cpu, policy->min, policy->max,
 161                         cpu_cur_freq[cpu], cpu_set_freq[cpu]);
 162                 if (policy->max < cpu_set_freq[cpu]) {
 163                         __cpufreq_driver_target(policy, policy->max,
 164                                                 CPUFREQ_RELATION_H);
 165                 }
 166                 else if (policy->min > cpu_set_freq[cpu]) {
 167                         __cpufreq_driver_target(policy, policy->min,
 168                                                 CPUFREQ_RELATION_L);
 169                 }
 170                 else {
 171                         __cpufreq_driver_target(policy, cpu_set_freq[cpu],
 172                                                 CPUFREQ_RELATION_L);
 173                 }
 174                 cpu_min_freq[cpu] = policy->min;
 175                 cpu_max_freq[cpu] = policy->max;
 176                 cpu_cur_freq[cpu] = policy->cur;
 177                 mutex_unlock(&userspace_mutex);
 178                 break;
 179         }
 180         return 0;
 181 }
 182
 183
 184 struct cpufreq_governor cpufreq_gov_userspace = {
 185         .name           = "userspace",
 186         .governor       = cpufreq_governor_userspace,
 187         .owner          = THIS_MODULE,
 188 };
 189 EXPORT_SYMBOL(cpufreq_gov_userspace);
 190
 191 static int __init cpufreq_gov_userspace_init(void)
 192 {
 193         cpufreq_register_notifier(&userspace_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER);
 194         return cpufreq_register_governor(&cpufreq_gov_userspace);
 195 }
 196
 197
 198 static void __exit cpufreq_gov_userspace_exit(void)
 199 {
 200         cpufreq_unregister_governor(&cpufreq_gov_userspace);
 201         cpufreq_unregister_notifier(&userspace_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER);
 202 }
 203
 204
 205 MODULE_AUTHOR ("Dominik Brodowski <linux@brodo.de>, Russell King <rmk@arm.linux.org.uk>");
 206 MODULE_DESCRIPTION ("CPUfreq policy governor 'userspace'");
 207 MODULE_LICENSE ("GPL");
 208
 209 fs_initcall(cpufreq_gov_userspace_init);
 210 module_exit(cpufreq_gov_userspace_exit);