drivers/cpufreq/cpufreq_userspace.c

   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  */
  31 static unsigned int     cpu_max_freq[NR_CPUS];
  32 static unsigned int     cpu_min_freq[NR_CPUS];
  33 static unsigned int     cpu_cur_freq[NR_CPUS]; /* current CPU freq */
  34 static unsigned int     cpu_set_freq[NR_CPUS]; /* CPU freq desired by userspace */
  35 static unsigned int     cpu_is_managed[NR_CPUS];
  36 static struct cpufreq_policy current_policy[NR_CPUS];
  37
  38 static DECLARE_MUTEX    (userspace_sem);
  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, 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 ************************/
 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->cpu);
 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         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
 181 struct cpufreq_governor cpufreq_gov_userspace = {
 182         .name           = "userspace",
 183         .governor       = cpufreq_governor_userspace,
 184         .owner          = THIS_MODULE,
 185 };
 186 EXPORT_SYMBOL(cpufreq_gov_userspace);
 187
 188 static 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
 195 static 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
 202 MODULE_AUTHOR ("Dominik Brodowski <linux@brodo.de>, Russell King <rmk@arm.linux.org.uk>");
 203 MODULE_DESCRIPTION ("CPUfreq policy governor 'userspace'");
 204 MODULE_LICENSE ("GPL");
 205
 206 fs_initcall(cpufreq_gov_userspace_init);
 207 module_exit(cpufreq_gov_userspace_exit);