1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * linux/drivers/devfreq/governor_userspace.c 4 * 5 * Copyright (C) 2011 Samsung Electronics 6 * MyungJoo Ham <myungjoo.ham@samsung.com> 7 */ 8 9 #include <linux/slab.h> 10 #include <linux/device.h> 11 #include <linux/devfreq.h> 12 #include <linux/devfreq-governor.h> 13 #include <linux/kstrtox.h> 14 #include <linux/pm.h> 15 #include <linux/mutex.h> 16 #include <linux/module.h> 17 18 struct userspace_data { 19 unsigned long user_frequency; 20 bool valid; 21 }; 22 23 static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq) 24 { 25 struct userspace_data *data = df->governor_data; 26 27 if (data->valid) 28 *freq = data->user_frequency; 29 else 30 *freq = df->previous_freq; /* No user freq specified yet */ 31 32 return 0; 33 } 34 35 static ssize_t set_freq_store(struct device *dev, struct device_attribute *attr, 36 const char *buf, size_t count) 37 { 38 struct devfreq *devfreq = to_devfreq(dev); 39 struct userspace_data *data; 40 unsigned long wanted; 41 int err = 0; 42 43 err = kstrtoul(buf, 0, &wanted); 44 if (err) 45 return err; 46 47 mutex_lock(&devfreq->lock); 48 data = devfreq->governor_data; 49 50 data->user_frequency = wanted; 51 data->valid = true; 52 err = update_devfreq(devfreq); 53 if (err == 0) 54 err = count; 55 mutex_unlock(&devfreq->lock); 56 return err; 57 } 58 59 static ssize_t set_freq_show(struct device *dev, 60 struct device_attribute *attr, char *buf) 61 { 62 struct devfreq *devfreq = to_devfreq(dev); 63 struct userspace_data *data; 64 int err = 0; 65 66 mutex_lock(&devfreq->lock); 67 data = devfreq->governor_data; 68 69 if (data->valid) 70 err = sprintf(buf, "%lu\n", data->user_frequency); 71 else 72 err = sprintf(buf, "undefined\n"); 73 mutex_unlock(&devfreq->lock); 74 return err; 75 } 76 77 static DEVICE_ATTR_RW(set_freq); 78 static struct attribute *dev_entries[] = { 79 &dev_attr_set_freq.attr, 80 NULL, 81 }; 82 static const struct attribute_group dev_attr_group = { 83 .name = DEVFREQ_GOV_USERSPACE, 84 .attrs = dev_entries, 85 }; 86 87 static int userspace_init(struct devfreq *devfreq) 88 { 89 int err = 0; 90 struct userspace_data *data = kzalloc_obj(struct userspace_data); 91 92 if (!data) { 93 err = -ENOMEM; 94 goto out; 95 } 96 data->valid = false; 97 devfreq->governor_data = data; 98 99 err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group); 100 out: 101 return err; 102 } 103 104 static void userspace_exit(struct devfreq *devfreq) 105 { 106 /* 107 * Remove the sysfs entry, unless this is being called after 108 * device_del(), which should have done this already via kobject_del(). 109 */ 110 if (devfreq->dev.kobj.sd) 111 sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group); 112 113 kfree(devfreq->governor_data); 114 devfreq->governor_data = NULL; 115 } 116 117 static int devfreq_userspace_handler(struct devfreq *devfreq, 118 unsigned int event, void *data) 119 { 120 int ret = 0; 121 122 switch (event) { 123 case DEVFREQ_GOV_START: 124 ret = userspace_init(devfreq); 125 break; 126 case DEVFREQ_GOV_STOP: 127 userspace_exit(devfreq); 128 break; 129 default: 130 break; 131 } 132 133 return ret; 134 } 135 136 static struct devfreq_governor devfreq_userspace = { 137 .name = DEVFREQ_GOV_USERSPACE, 138 .get_target_freq = devfreq_userspace_func, 139 .event_handler = devfreq_userspace_handler, 140 }; 141 142 static int __init devfreq_userspace_init(void) 143 { 144 return devfreq_add_governor(&devfreq_userspace); 145 } 146 subsys_initcall(devfreq_userspace_init); 147 148 static void __exit devfreq_userspace_exit(void) 149 { 150 int ret; 151 152 ret = devfreq_remove_governor(&devfreq_userspace); 153 if (ret) 154 pr_err("%s: failed remove governor %d\n", __func__, ret); 155 156 return; 157 } 158 module_exit(devfreq_userspace_exit); 159 MODULE_DESCRIPTION("DEVFREQ Userspace governor"); 160 MODULE_LICENSE("GPL"); 161