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 DEFINE_PER_CPU(unsigned int, cpu_max_freq);
  34 static DEFINE_PER_CPU(unsigned int, cpu_min_freq);
  35 static DEFINE_PER_CPU(unsigned int, cpu_cur_freq); /* current CPU freq */
  36 static DEFINE_PER_CPU(unsigned int, cpu_set_freq); /* CPU freq desired by
  37                                                         userspace */
  38 static DEFINE_PER_CPU(unsigned int, cpu_is_managed);
  39
  40 static DEFINE_MUTEX     (userspace_mutex);
  41 static int cpus_using_userspace_governor;
  42
  43 #define dprintk(msg...) \
  44         cpufreq_debug_printk(CPUFREQ_DEBUG_GOVERNOR, "userspace", msg)
  45
  46 /* keep track of frequency transitions */
  47 static int
  48 userspace_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
  49                        void *data)
  50 {
  51         struct cpufreq_freqs *freq = data;
  52
  53         if (!per_cpu(cpu_is_managed, freq->cpu))
  54                 return 0;
  55
  56         dprintk("saving cpu_cur_freq of cpu %u to be %u kHz\n",
  57                         freq->cpu, freq->new);
  58         per_cpu(cpu_cur_freq, freq->cpu) = freq->new;
  59
  60         return 0;
  61 }
  62
  63 static struct notifier_block userspace_cpufreq_notifier_block = {
  64         .notifier_call  = userspace_cpufreq_notifier
  65 };
  66
  67
  68 /**
  69  * cpufreq_set - set the CPU frequency
  70  * @policy: pointer to policy struct where freq is being set
  71  * @freq: target frequency in kHz
  72  *
  73  * Sets the CPU frequency to freq.
  74  */
  75 static int cpufreq_set(struct cpufreq_policy *policy, unsigned int freq)
  76 {
  77         int ret = -EINVAL;
  78
  79         dprintk("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);
  80
  81         mutex_lock(&userspace_mutex);
  82         if (!per_cpu(cpu_is_managed, policy->cpu))
  83                 goto err;
  84
  85         per_cpu(cpu_set_freq, policy->cpu) = freq;
  86
  87         if (freq < per_cpu(cpu_min_freq, policy->cpu))
  88                 freq = per_cpu(cpu_min_freq, policy->cpu);
  89         if (freq > per_cpu(cpu_max_freq, policy->cpu))
  90                 freq = per_cpu(cpu_max_freq, policy->cpu);
  91
  92         /*
  93          * We're safe from concurrent calls to ->target() here
  94          * as we hold the userspace_mutex lock. If we were calling
  95          * cpufreq_driver_target, a deadlock situation might occur:
  96          * A: cpufreq_set (lock userspace_mutex) -> cpufreq_driver_target(lock policy->lock)
  97          * B: cpufreq_set_policy(lock policy->lock) -> __cpufreq_governor -> cpufreq_governor_userspace (lock userspace_mutex)
  98          */
  99         ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
 100
 101  err:
 102         mutex_unlock(&userspace_mutex);
 103         return ret;
 104 }
 105
 106
 107 static ssize_t show_speed(struct cpufreq_policy *policy, char *buf)
 108 {
 109         return sprintf(buf, "%u\n", per_cpu(cpu_cur_freq, policy->cpu));
 110 }
 111
 112 static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
 113                                    unsigned int event)
 114 {
 115         unsigned int cpu = policy->cpu;
 116         int rc = 0;
 117
 118         switch (event) {
 119         case CPUFREQ_GOV_START:
 120                 if (!cpu_online(cpu))
 121                         return -EINVAL;
 122                 BUG_ON(!policy->cur);
 123                 mutex_lock(&userspace_mutex);
 124
 125                 if (cpus_using_userspace_governor == 0) {
 126                         cpufreq_register_notifier(
 127                                         &userspace_cpufreq_notifier_block,
 128                                         CPUFREQ_TRANSITION_NOTIFIER);
 129                 }
 130                 cpus_using_userspace_governor++;
 131
 132                 per_cpu(cpu_is_managed, cpu) = 1;
 133                 per_cpu(cpu_min_freq, cpu) = policy->min;
 134                 per_cpu(cpu_max_freq, cpu) = policy->max;
 135                 per_cpu(cpu_cur_freq, cpu) = policy->cur;
 136                 per_cpu(cpu_set_freq, cpu) = policy->cur;
 137                 dprintk("managing cpu %u started "
 138                         "(%u - %u kHz, currently %u kHz)\n",
 139                                 cpu,
 140                                 per_cpu(cpu_min_freq, cpu),
 141                                 per_cpu(cpu_max_freq, cpu),
 142                                 per_cpu(cpu_cur_freq, cpu));
 143
 144                 mutex_unlock(&userspace_mutex);
 145                 break;
 146         case CPUFREQ_GOV_STOP:
 147                 mutex_lock(&userspace_mutex);
 148                 cpus_using_userspace_governor--;
 149                 if (cpus_using_userspace_governor == 0) {
 150                         cpufreq_unregister_notifier(
 151                                         &userspace_cpufreq_notifier_block,
 152                                         CPUFREQ_TRANSITION_NOTIFIER);
 153                 }
 154
 155                 per_cpu(cpu_is_managed, cpu) = 0;
 156                 per_cpu(cpu_min_freq, cpu) = 0;
 157                 per_cpu(cpu_max_freq, cpu) = 0;
 158                 per_cpu(cpu_set_freq, cpu) = 0;
 159                 dprintk("managing cpu %u stopped\n", cpu);
 160                 mutex_unlock(&userspace_mutex);
 161                 break;
 162         case CPUFREQ_GOV_LIMITS:
 163                 mutex_lock(&userspace_mutex);
 164                 dprintk("limit event for cpu %u: %u - %u kHz, "
 165                         "currently %u kHz, last set to %u kHz\n",
 166                         cpu, policy->min, policy->max,
 167                         per_cpu(cpu_cur_freq, cpu),
 168                         per_cpu(cpu_set_freq, cpu));
 169                 if (policy->max < per_cpu(cpu_set_freq, cpu)) {
 170                         __cpufreq_driver_target(policy, policy->max,
 171                                                 CPUFREQ_RELATION_H);
 172                 } else if (policy->min > per_cpu(cpu_set_freq, cpu)) {
 173                         __cpufreq_driver_target(policy, policy->min,
 174                                                 CPUFREQ_RELATION_L);
 175                 } else {
 176                         __cpufreq_driver_target(policy,
 177                                                 per_cpu(cpu_set_freq, cpu),
 178                                                 CPUFREQ_RELATION_L);
 179                 }
 180                 per_cpu(cpu_min_freq, cpu) = policy->min;
 181                 per_cpu(cpu_max_freq, cpu) = policy->max;
 182                 per_cpu(cpu_cur_freq, cpu) = policy->cur;
 183                 mutex_unlock(&userspace_mutex);
 184                 break;
 185         }
 186         return rc;
 187 }
 188
 189
 190 struct cpufreq_governor cpufreq_gov_userspace = {
 191         .name           = "userspace",
 192         .governor       = cpufreq_governor_userspace,
 193         .store_setspeed = cpufreq_set,
 194         .show_setspeed  = show_speed,
 195         .owner          = THIS_MODULE,
 196 };
 197 EXPORT_SYMBOL(cpufreq_gov_userspace);
 198
 199 static int __init cpufreq_gov_userspace_init(void)
 200 {
 201         return cpufreq_register_governor(&cpufreq_gov_userspace);
 202 }
 203
 204
 205 static void __exit cpufreq_gov_userspace_exit(void)
 206 {
 207         cpufreq_unregister_governor(&cpufreq_gov_userspace);
 208 }
 209
 210
 211 MODULE_AUTHOR ("Dominik Brodowski <linux@brodo.de>, Russell King <rmk@arm.linux.org.uk>");
 212 MODULE_DESCRIPTION ("CPUfreq policy governor 'userspace'");
 213 MODULE_LICENSE ("GPL");
 214
 215 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
 216 fs_initcall(cpufreq_gov_userspace_init);
 217 #else
 218 module_init(cpufreq_gov_userspace_init);
 219 #endif
 220 module_exit(cpufreq_gov_userspace_exit);