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/pm.h> 13 #include <linux/mutex.h> 14 #include <linux/module.h> 15 #include "governor.h" 16 17 struct userspace_data { 18 unsigned long user_frequency; 19 bool valid; 20 }; 21 22 static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq) 23 { 24 struct userspace_data *data = df->data; 25 26 if (data->valid) 27 *freq = data->user_frequency; 28 else 29 *freq = df->previous_freq; /* No user freq specified yet */ 30 31 return 0; 32 } 33 34 static ssize_t store_freq(struct device *dev, struct device_attribute *attr, 35 const char *buf, size_t count) 36 { 37 struct devfreq *devfreq = to_devfreq(dev); 38 struct userspace_data *data; 39 unsigned long wanted; 40 int err = 0; 41 42 mutex_lock(&devfreq->lock); 43 data = devfreq->data; 44 45 sscanf(buf, "%lu", &wanted); 46 data->user_frequency = wanted; 47 data->valid = true; 48 err = update_devfreq(devfreq); 49 if (err == 0) 50 err = count; 51 mutex_unlock(&devfreq->lock); 52 return err; 53 } 54 55 static ssize_t show_freq(struct device *dev, struct device_attribute *attr, 56 char *buf) 57 { 58 struct devfreq *devfreq = to_devfreq(dev); 59 struct userspace_data *data; 60 int err = 0; 61 62 mutex_lock(&devfreq->lock); 63 data = devfreq->data; 64 65 if (data->valid) 66 err = sprintf(buf, "%lu\n", data->user_frequency); 67 else 68 err = sprintf(buf, "undefined\n"); 69 mutex_unlock(&devfreq->lock); 70 return err; 71 } 72 73 static DEVICE_ATTR(set_freq, 0644, show_freq, store_freq); 74 static struct attribute *dev_entries[] = { 75 &dev_attr_set_freq.attr, 76 NULL, 77 }; 78 static const struct attribute_group dev_attr_group = { 79 .name = DEVFREQ_GOV_USERSPACE, 80 .attrs = dev_entries, 81 }; 82 83 static int userspace_init(struct devfreq *devfreq) 84 { 85 int err = 0; 86 struct userspace_data *data = kzalloc(sizeof(struct userspace_data), 87 GFP_KERNEL); 88 89 if (!data) { 90 err = -ENOMEM; 91 goto out; 92 } 93 data->valid = false; 94 devfreq->data = data; 95 96 err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group); 97 out: 98 return err; 99 } 100 101 static void userspace_exit(struct devfreq *devfreq) 102 { 103 /* 104 * Remove the sysfs entry, unless this is being called after 105 * device_del(), which should have done this already via kobject_del(). 106 */ 107 if (devfreq->dev.kobj.sd) 108 sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group); 109 110 kfree(devfreq->data); 111 devfreq->data = NULL; 112 } 113 114 static int devfreq_userspace_handler(struct devfreq *devfreq, 115 unsigned int event, void *data) 116 { 117 int ret = 0; 118 119 switch (event) { 120 case DEVFREQ_GOV_START: 121 ret = userspace_init(devfreq); 122 break; 123 case DEVFREQ_GOV_STOP: 124 userspace_exit(devfreq); 125 break; 126 default: 127 break; 128 } 129 130 return ret; 131 } 132 133 static struct devfreq_governor devfreq_userspace = { 134 .name = DEVFREQ_GOV_USERSPACE, 135 .get_target_freq = devfreq_userspace_func, 136 .event_handler = devfreq_userspace_handler, 137 }; 138 139 static int __init devfreq_userspace_init(void) 140 { 141 return devfreq_add_governor(&devfreq_userspace); 142 } 143 subsys_initcall(devfreq_userspace_init); 144 145 static void __exit devfreq_userspace_exit(void) 146 { 147 int ret; 148 149 ret = devfreq_remove_governor(&devfreq_userspace); 150 if (ret) 151 pr_err("%s: failed remove governor %d\n", __func__, ret); 152 153 return; 154 } 155 module_exit(devfreq_userspace_exit); 156 MODULE_LICENSE("GPL"); 157