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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  15
  16 #include <linux/cpufreq.h>
  17 #include <linux/init.h>
  18 #include <linux/module.h>
  19 #include <linux/mutex.h>
  20 #include <linux/slab.h>
  21
  22 static DEFINE_PER_CPU(unsigned int, cpu_is_managed);
  23 static DEFINE_MUTEX(userspace_mutex);
  24
  25 /**
  26  * cpufreq_set - set the CPU frequency
  27  * @policy: pointer to policy struct where freq is being set
  28  * @freq: target frequency in kHz
  29  *
  30  * Sets the CPU frequency to freq.
  31  */
  32 static int cpufreq_set(struct cpufreq_policy *policy, unsigned int freq)
  33 {
  34         int ret = -EINVAL;
  35         unsigned int *setspeed = policy->governor_data;
  36
  37         pr_debug("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);
  38
  39         mutex_lock(&userspace_mutex);
  40         if (!per_cpu(cpu_is_managed, policy->cpu))
  41                 goto err;
  42
  43         *setspeed = freq;
  44
  45         ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
  46  err:
  47         mutex_unlock(&userspace_mutex);
  48         return ret;
  49 }
  50
  51 static ssize_t show_speed(struct cpufreq_policy *policy, char *buf)
  52 {
  53         return sprintf(buf, "%u\n", policy->cur);
  54 }
  55
  56 static int cpufreq_userspace_policy_init(struct cpufreq_policy *policy)
  57 {
  58         unsigned int *setspeed;
  59
  60         setspeed = kzalloc(sizeof(*setspeed), GFP_KERNEL);
  61         if (!setspeed)
  62                 return -ENOMEM;
  63
  64         policy->governor_data = setspeed;
  65         return 0;
  66 }
  67
  68 static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
  69                                    unsigned int event)
  70 {
  71         unsigned int *setspeed = policy->governor_data;
  72         unsigned int cpu = policy->cpu;
  73         int rc = 0;
  74
  75         if (event == CPUFREQ_GOV_POLICY_INIT)
  76                 return cpufreq_userspace_policy_init(policy);
  77
  78         if (!setspeed)
  79                 return -EINVAL;
  80
  81         switch (event) {
  82         case CPUFREQ_GOV_POLICY_EXIT:
  83                 mutex_lock(&userspace_mutex);
  84                 policy->governor_data = NULL;
  85                 kfree(setspeed);
  86                 mutex_unlock(&userspace_mutex);
  87                 break;
  88         case CPUFREQ_GOV_START:
  89                 BUG_ON(!policy->cur);
  90                 pr_debug("started managing cpu %u\n", cpu);
  91
  92                 mutex_lock(&userspace_mutex);
  93                 per_cpu(cpu_is_managed, cpu) = 1;
  94                 *setspeed = policy->cur;
  95                 mutex_unlock(&userspace_mutex);
  96                 break;
  97         case CPUFREQ_GOV_STOP:
  98                 pr_debug("managing cpu %u stopped\n", cpu);
  99
 100                 mutex_lock(&userspace_mutex);
 101                 per_cpu(cpu_is_managed, cpu) = 0;
 102                 *setspeed = 0;
 103                 mutex_unlock(&userspace_mutex);
 104                 break;
 105         case CPUFREQ_GOV_LIMITS:
 106                 mutex_lock(&userspace_mutex);
 107                 pr_debug("limit event for cpu %u: %u - %u kHz, currently %u kHz, last set to %u kHz\n",
 108                         cpu, policy->min, policy->max, policy->cur, *setspeed);
 109
 110                 if (policy->max < *setspeed)
 111                         __cpufreq_driver_target(policy, policy->max,
 112                                                 CPUFREQ_RELATION_H);
 113                 else if (policy->min > *setspeed)
 114                         __cpufreq_driver_target(policy, policy->min,
 115                                                 CPUFREQ_RELATION_L);
 116                 else
 117                         __cpufreq_driver_target(policy, *setspeed,
 118                                                 CPUFREQ_RELATION_L);
 119                 mutex_unlock(&userspace_mutex);
 120                 break;
 121         }
 122         return rc;
 123 }
 124
 125 static struct cpufreq_governor cpufreq_gov_userspace = {
 126         .name           = "userspace",
 127         .governor       = cpufreq_governor_userspace,
 128         .store_setspeed = cpufreq_set,
 129         .show_setspeed  = show_speed,
 130         .owner          = THIS_MODULE,
 131 };
 132
 133 static int __init cpufreq_gov_userspace_init(void)
 134 {
 135         return cpufreq_register_governor(&cpufreq_gov_userspace);
 136 }
 137
 138 static void __exit cpufreq_gov_userspace_exit(void)
 139 {
 140         cpufreq_unregister_governor(&cpufreq_gov_userspace);
 141 }
 142
 143 MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>, "
 144                 "Russell King <rmk@arm.linux.org.uk>");
 145 MODULE_DESCRIPTION("CPUfreq policy governor 'userspace'");
 146 MODULE_LICENSE("GPL");
 147
 148 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
 149 struct cpufreq_governor *cpufreq_default_governor(void)
 150 {
 151         return &cpufreq_gov_userspace;
 152 }
 153
 154 fs_initcall(cpufreq_gov_userspace_init);
 155 #else
 156 module_init(cpufreq_gov_userspace_init);
 157 #endif
 158 module_exit(cpufreq_gov_userspace_exit);