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 static int cpus_using_userspace_governor;
  41
  42 #define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_GOVERNOR, "userspace", msg)
  43
  44 /* keep track of frequency transitions */
  45 static int
  46 userspace_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
  47                        void *data)
  48 {
  49         struct cpufreq_freqs *freq = data;
  50
  51         if (!cpu_is_managed[freq->cpu])
  52                 return 0;
  53
  54         dprintk("saving cpu_cur_freq of cpu %u to be %u kHz\n",
  55                         freq->cpu, freq->new);
  56         cpu_cur_freq[freq->cpu] = freq->new;
  57
  58         return 0;
  59 }
  60
  61 static struct notifier_block userspace_cpufreq_notifier_block = {
  62         .notifier_call  = userspace_cpufreq_notifier
  63 };
  64
  65
  66 /**
  67  * cpufreq_set - set the CPU frequency
  68  * @freq: target frequency in kHz
  69  * @cpu: CPU for which the frequency is to be set
  70  *
  71  * Sets the CPU frequency to freq.
  72  */
  73 static int cpufreq_set(unsigned int freq, struct cpufreq_policy *policy)
  74 {
  75         int ret = -EINVAL;
  76
  77         dprintk("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);
  78
  79         mutex_lock(&userspace_mutex);
  80         if (!cpu_is_managed[policy->cpu])
  81                 goto err;
  82
  83         cpu_set_freq[policy->cpu] = freq;
  84
  85         if (freq < cpu_min_freq[policy->cpu])
  86                 freq = cpu_min_freq[policy->cpu];
  87         if (freq > cpu_max_freq[policy->cpu])
  88                 freq = cpu_max_freq[policy->cpu];
  89
  90         /*
  91          * We're safe from concurrent calls to ->target() here
  92          * as we hold the userspace_mutex lock. If we were calling
  93          * cpufreq_driver_target, a deadlock situation might occur:
  94          * A: cpufreq_set (lock userspace_mutex) -> cpufreq_driver_target(lock policy->lock)
  95          * B: cpufreq_set_policy(lock policy->lock) -> __cpufreq_governor -> cpufreq_governor_userspace (lock userspace_mutex)
  96          */
  97         ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
  98
  99  err:
 100         mutex_unlock(&userspace_mutex);
 101         return ret;
 102 }
 103
 104
 105 /************************** sysfs interface ************************/
 106 static ssize_t show_speed (struct cpufreq_policy *policy, char *buf)
 107 {
 108         return sprintf (buf, "%u\n", cpu_cur_freq[policy->cpu]);
 109 }
 110
 111 static ssize_t
 112 store_speed (struct cpufreq_policy *policy, const char *buf, size_t count)
 113 {
 114         unsigned int freq = 0;
 115         unsigned int ret;
 116
 117         ret = sscanf (buf, "%u", &freq);
 118         if (ret != 1)
 119                 return -EINVAL;
 120
 121         cpufreq_set(freq, policy);
 122
 123         return count;
 124 }
 125
 126 static struct freq_attr freq_attr_scaling_setspeed =
 127 {
 128         .attr = { .name = "scaling_setspeed", .mode = 0644 },
 129         .show = show_speed,
 130         .store = store_speed,
 131 };
 132
 133 static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
 134                                    unsigned int event)
 135 {
 136         unsigned int cpu = policy->cpu;
 137         int rc = 0;
 138
 139         switch (event) {
 140         case CPUFREQ_GOV_START:
 141                 if (!cpu_online(cpu))
 142                         return -EINVAL;
 143                 BUG_ON(!policy->cur);
 144                 mutex_lock(&userspace_mutex);
 145                 rc = sysfs_create_file (&policy->kobj,
 146                                         &freq_attr_scaling_setspeed.attr);
 147                 if (rc)
 148                         goto start_out;
 149
 150                 if (cpus_using_userspace_governor == 0) {
 151                         cpufreq_register_notifier(
 152                                         &userspace_cpufreq_notifier_block,
 153                                         CPUFREQ_TRANSITION_NOTIFIER);
 154                 }
 155                 cpus_using_userspace_governor++;
 156
 157                 cpu_is_managed[cpu] = 1;
 158                 cpu_min_freq[cpu] = policy->min;
 159                 cpu_max_freq[cpu] = policy->max;
 160                 cpu_cur_freq[cpu] = policy->cur;
 161                 cpu_set_freq[cpu] = policy->cur;
 162                 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]);
 163 start_out:
 164                 mutex_unlock(&userspace_mutex);
 165                 break;
 166         case CPUFREQ_GOV_STOP:
 167                 mutex_lock(&userspace_mutex);
 168                 cpus_using_userspace_governor--;
 169                 if (cpus_using_userspace_governor == 0) {
 170                         cpufreq_unregister_notifier(
 171                                         &userspace_cpufreq_notifier_block,
 172                                         CPUFREQ_TRANSITION_NOTIFIER);
 173                 }
 174
 175                 cpu_is_managed[cpu] = 0;
 176                 cpu_min_freq[cpu] = 0;
 177                 cpu_max_freq[cpu] = 0;
 178                 cpu_set_freq[cpu] = 0;
 179                 sysfs_remove_file (&policy->kobj, &freq_attr_scaling_setspeed.attr);
 180                 dprintk("managing cpu %u stopped\n", cpu);
 181                 mutex_unlock(&userspace_mutex);
 182                 break;
 183         case CPUFREQ_GOV_LIMITS:
 184                 mutex_lock(&userspace_mutex);
 185                 dprintk("limit event for cpu %u: %u - %u kHz,"
 186                         "currently %u kHz, last set to %u kHz\n",
 187                         cpu, policy->min, policy->max,
 188                         cpu_cur_freq[cpu], cpu_set_freq[cpu]);
 189                 if (policy->max < cpu_set_freq[cpu]) {
 190                         __cpufreq_driver_target(policy, policy->max,
 191                                                 CPUFREQ_RELATION_H);
 192                 }
 193                 else if (policy->min > cpu_set_freq[cpu]) {
 194                         __cpufreq_driver_target(policy, policy->min,
 195                                                 CPUFREQ_RELATION_L);
 196                 }
 197                 else {
 198                         __cpufreq_driver_target(policy, cpu_set_freq[cpu],
 199                                                 CPUFREQ_RELATION_L);
 200                 }
 201                 cpu_min_freq[cpu] = policy->min;
 202                 cpu_max_freq[cpu] = policy->max;
 203                 cpu_cur_freq[cpu] = policy->cur;
 204                 mutex_unlock(&userspace_mutex);
 205                 break;
 206         }
 207         return rc;
 208 }
 209
 210
 211 struct cpufreq_governor cpufreq_gov_userspace = {
 212         .name           = "userspace",
 213         .governor       = cpufreq_governor_userspace,
 214         .owner          = THIS_MODULE,
 215 };
 216 EXPORT_SYMBOL(cpufreq_gov_userspace);
 217
 218 static int __init cpufreq_gov_userspace_init(void)
 219 {
 220         return cpufreq_register_governor(&cpufreq_gov_userspace);
 221 }
 222
 223
 224 static void __exit cpufreq_gov_userspace_exit(void)
 225 {
 226         cpufreq_unregister_governor(&cpufreq_gov_userspace);
 227 }
 228
 229
 230 MODULE_AUTHOR ("Dominik Brodowski <linux@brodo.de>, Russell King <rmk@arm.linux.org.uk>");
 231 MODULE_DESCRIPTION ("CPUfreq policy governor 'userspace'");
 232 MODULE_LICENSE ("GPL");
 233
 234 fs_initcall(cpufreq_gov_userspace_init);
 235 module_exit(cpufreq_gov_userspace_exit);