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 struct userspace_policy *userspace = policy->governor_data; 53 54 return sprintf(buf, "%u\n", userspace->setspeed); 55 } 56 57 static int cpufreq_userspace_policy_init(struct cpufreq_policy *policy) 58 { 59 struct userspace_policy *userspace; 60 61 userspace = kzalloc(sizeof(*userspace), GFP_KERNEL); 62 if (!userspace) 63 return -ENOMEM; 64 65 mutex_init(&userspace->mutex); 66 67 policy->governor_data = userspace; 68 return 0; 69 } 70 71 /* 72 * Any routine that writes to the policy struct will hold the "rwsem" of 73 * policy struct that means it is free to free "governor_data" here. 74 */ 75 static void cpufreq_userspace_policy_exit(struct cpufreq_policy *policy) 76 { 77 kfree(policy->governor_data); 78 policy->governor_data = NULL; 79 } 80 81 static int cpufreq_userspace_policy_start(struct cpufreq_policy *policy) 82 { 83 struct userspace_policy *userspace = policy->governor_data; 84 85 BUG_ON(!policy->cur); 86 pr_debug("started managing cpu %u\n", policy->cpu); 87 88 mutex_lock(&userspace->mutex); 89 userspace->is_managed = 1; 90 userspace->setspeed = policy->cur; 91 mutex_unlock(&userspace->mutex); 92 return 0; 93 } 94 95 static void cpufreq_userspace_policy_stop(struct cpufreq_policy *policy) 96 { 97 struct userspace_policy *userspace = policy->governor_data; 98 99 pr_debug("managing cpu %u stopped\n", policy->cpu); 100 101 mutex_lock(&userspace->mutex); 102 userspace->is_managed = 0; 103 userspace->setspeed = 0; 104 mutex_unlock(&userspace->mutex); 105 } 106 107 static void cpufreq_userspace_policy_limits(struct cpufreq_policy *policy) 108 { 109 struct userspace_policy *userspace = policy->governor_data; 110 111 mutex_lock(&userspace->mutex); 112 113 pr_debug("limit event for cpu %u: %u - %u kHz, currently %u kHz, last set to %u kHz\n", 114 policy->cpu, policy->min, policy->max, policy->cur, userspace->setspeed); 115 116 if (policy->max < userspace->setspeed) 117 __cpufreq_driver_target(policy, policy->max, 118 CPUFREQ_RELATION_H); 119 else if (policy->min > userspace->setspeed) 120 __cpufreq_driver_target(policy, policy->min, 121 CPUFREQ_RELATION_L); 122 else 123 __cpufreq_driver_target(policy, userspace->setspeed, 124 CPUFREQ_RELATION_L); 125 126 mutex_unlock(&userspace->mutex); 127 } 128 129 static struct cpufreq_governor cpufreq_gov_userspace = { 130 .name = "userspace", 131 .init = cpufreq_userspace_policy_init, 132 .exit = cpufreq_userspace_policy_exit, 133 .start = cpufreq_userspace_policy_start, 134 .stop = cpufreq_userspace_policy_stop, 135 .limits = cpufreq_userspace_policy_limits, 136 .store_setspeed = cpufreq_set, 137 .show_setspeed = show_speed, 138 .owner = THIS_MODULE, 139 .flags = CPUFREQ_GOV_STRICT_TARGET, 140 }; 141 142 MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>, " 143 "Russell King <rmk@arm.linux.org.uk>"); 144 MODULE_DESCRIPTION("CPUfreq policy governor 'userspace'"); 145 MODULE_LICENSE("GPL"); 146 147 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE 148 struct cpufreq_governor *cpufreq_default_governor(void) 149 { 150 return &cpufreq_gov_userspace; 151 } 152 #endif 153 154 cpufreq_governor_init(cpufreq_gov_userspace); 155 cpufreq_governor_exit(cpufreq_gov_userspace); 156