drivers/cpufreq/cpufreq_userspace.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2
   3 /*
   4  *  linux/drivers/cpufreq/cpufreq_userspace.c
   5  *
   6  *  Copyright (C)  2001 Russell King
   7  *            (C)  2002 - 2004 Dominik Brodowski <linux@brodo.de>
   8  */
   9
  10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11
  12 #include <linux/cpufreq.h>
  13 #include <linux/init.h>
  14 #include <linux/module.h>
  15 #include <linux/mutex.h>
  16 #include <linux/slab.h>
  17
  18 struct userspace_policy {
  19         unsigned int is_managed;
  20         unsigned int setspeed;
  21         struct mutex mutex;
  22 };
  23
  24 /**
  25  * cpufreq_set - set the CPU frequency
  26  * @policy: pointer to policy struct where freq is being set
  27  * @freq: target frequency in kHz
  28  *
  29  * Sets the CPU frequency to freq.
  30  */
  31 static int cpufreq_set(struct cpufreq_policy *policy, unsigned int freq)
  32 {
  33         int ret = -EINVAL;
  34         struct userspace_policy *userspace = policy->governor_data;
  35
  36         pr_debug("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);
  37
  38         mutex_lock(&userspace->mutex);
  39         if (!userspace->is_managed)
  40                 goto err;
  41
  42         userspace->setspeed = freq;
  43
  44         ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
  45  err:
  46         mutex_unlock(&userspace->mutex);
  47         return ret;
  48 }
  49
  50 static ssize_t show_speed(struct cpufreq_policy *policy, char *buf)
  51 {
  52         return sprintf(buf, "%u\n", policy->cur);
  53 }
  54
  55 static int cpufreq_userspace_policy_init(struct cpufreq_policy *policy)
  56 {
  57         struct userspace_policy *userspace;
  58
  59         userspace = kzalloc(sizeof(*userspace), GFP_KERNEL);
  60         if (!userspace)
  61                 return -ENOMEM;
  62
  63         mutex_init(&userspace->mutex);
  64
  65         policy->governor_data = userspace;
  66         return 0;
  67 }
  68
  69 /*
  70  * Any routine that writes to the policy struct will hold the "rwsem" of
  71  * policy struct that means it is free to free "governor_data" here.
  72  */
  73 static void cpufreq_userspace_policy_exit(struct cpufreq_policy *policy)
  74 {
  75         kfree(policy->governor_data);
  76         policy->governor_data = NULL;
  77 }
  78
  79 static int cpufreq_userspace_policy_start(struct cpufreq_policy *policy)
  80 {
  81         struct userspace_policy *userspace = policy->governor_data;
  82
  83         BUG_ON(!policy->cur);
  84         pr_debug("started managing cpu %u\n", policy->cpu);
  85
  86         mutex_lock(&userspace->mutex);
  87         userspace->is_managed = 1;
  88         userspace->setspeed = policy->cur;
  89         mutex_unlock(&userspace->mutex);
  90         return 0;
  91 }
  92
  93 static void cpufreq_userspace_policy_stop(struct cpufreq_policy *policy)
  94 {
  95         struct userspace_policy *userspace = policy->governor_data;
  96
  97         pr_debug("managing cpu %u stopped\n", policy->cpu);
  98
  99         mutex_lock(&userspace->mutex);
 100         userspace->is_managed = 0;
 101         userspace->setspeed = 0;
 102         mutex_unlock(&userspace->mutex);
 103 }
 104
 105 static void cpufreq_userspace_policy_limits(struct cpufreq_policy *policy)
 106 {
 107         struct userspace_policy *userspace = policy->governor_data;
 108
 109         mutex_lock(&userspace->mutex);
 110
 111         pr_debug("limit event for cpu %u: %u - %u kHz, currently %u kHz, last set to %u kHz\n",
 112                  policy->cpu, policy->min, policy->max, policy->cur, userspace->setspeed);
 113
 114         if (policy->max < userspace->setspeed)
 115                 __cpufreq_driver_target(policy, policy->max,
 116                                         CPUFREQ_RELATION_H);
 117         else if (policy->min > userspace->setspeed)
 118                 __cpufreq_driver_target(policy, policy->min,
 119                                         CPUFREQ_RELATION_L);
 120         else
 121                 __cpufreq_driver_target(policy, userspace->setspeed,
 122                                         CPUFREQ_RELATION_L);
 123
 124         mutex_unlock(&userspace->mutex);
 125 }
 126
 127 static struct cpufreq_governor cpufreq_gov_userspace = {
 128         .name           = "userspace",
 129         .init           = cpufreq_userspace_policy_init,
 130         .exit           = cpufreq_userspace_policy_exit,
 131         .start          = cpufreq_userspace_policy_start,
 132         .stop           = cpufreq_userspace_policy_stop,
 133         .limits         = cpufreq_userspace_policy_limits,
 134         .store_setspeed = cpufreq_set,
 135         .show_setspeed  = show_speed,
 136         .owner          = THIS_MODULE,
 137 };
 138
 139 MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>, "
 140                 "Russell King <rmk@arm.linux.org.uk>");
 141 MODULE_DESCRIPTION("CPUfreq policy governor 'userspace'");
 142 MODULE_LICENSE("GPL");
 143
 144 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
 145 struct cpufreq_governor *cpufreq_default_governor(void)
 146 {
 147         return &cpufreq_gov_userspace;
 148 }
 149 #endif
 150
 151 cpufreq_governor_init(cpufreq_gov_userspace);
 152 cpufreq_governor_exit(cpufreq_gov_userspace);