1 /* 2 * linux/drivers/devfreq/governor_userspace.c 3 * 4 * Copyright (C) 2011 Samsung Electronics 5 * MyungJoo Ham <myungjoo.ham@samsung.com> 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 */ 11 12 #include <linux/slab.h> 13 #include <linux/device.h> 14 #include <linux/devfreq.h> 15 #include <linux/pm.h> 16 #include <linux/mutex.h> 17 #include <linux/module.h> 18 #include "governor.h" 19 20 struct userspace_data { 21 unsigned long user_frequency; 22 bool valid; 23 }; 24 25 static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq) 26 { 27 struct userspace_data *data = df->data; 28 29 if (data->valid) { 30 unsigned long adjusted_freq = data->user_frequency; 31 32 if (df->max_freq && adjusted_freq > df->max_freq) 33 adjusted_freq = df->max_freq; 34 35 if (df->min_freq && adjusted_freq < df->min_freq) 36 adjusted_freq = df->min_freq; 37 38 *freq = adjusted_freq; 39 } else { 40 *freq = df->previous_freq; /* No user freq specified yet */ 41 } 42 return 0; 43 } 44 45 static ssize_t store_freq(struct device *dev, struct device_attribute *attr, 46 const char *buf, size_t count) 47 { 48 struct devfreq *devfreq = to_devfreq(dev); 49 struct userspace_data *data; 50 unsigned long wanted; 51 int err = 0; 52 53 mutex_lock(&devfreq->lock); 54 data = devfreq->data; 55 56 sscanf(buf, "%lu", &wanted); 57 data->user_frequency = wanted; 58 data->valid = true; 59 err = update_devfreq(devfreq); 60 if (err == 0) 61 err = count; 62 mutex_unlock(&devfreq->lock); 63 return err; 64 } 65 66 static ssize_t show_freq(struct device *dev, struct device_attribute *attr, 67 char *buf) 68 { 69 struct devfreq *devfreq = to_devfreq(dev); 70 struct userspace_data *data; 71 int err = 0; 72 73 mutex_lock(&devfreq->lock); 74 data = devfreq->data; 75 76 if (data->valid) 77 err = sprintf(buf, "%lu\n", data->user_frequency); 78 else 79 err = sprintf(buf, "undefined\n"); 80 mutex_unlock(&devfreq->lock); 81 return err; 82 } 83 84 static DEVICE_ATTR(set_freq, 0644, show_freq, store_freq); 85 static struct attribute *dev_entries[] = { 86 &dev_attr_set_freq.attr, 87 NULL, 88 }; 89 static const struct attribute_group dev_attr_group = { 90 .name = DEVFREQ_GOV_USERSPACE, 91 .attrs = dev_entries, 92 }; 93 94 static int userspace_init(struct devfreq *devfreq) 95 { 96 int err = 0; 97 struct userspace_data *data = kzalloc(sizeof(struct userspace_data), 98 GFP_KERNEL); 99 100 if (!data) { 101 err = -ENOMEM; 102 goto out; 103 } 104 data->valid = false; 105 devfreq->data = data; 106 107 err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group); 108 out: 109 return err; 110 } 111 112 static void userspace_exit(struct devfreq *devfreq) 113 { 114 /* 115 * Remove the sysfs entry, unless this is being called after 116 * device_del(), which should have done this already via kobject_del(). 117 */ 118 if (devfreq->dev.kobj.sd) 119 sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group); 120 121 kfree(devfreq->data); 122 devfreq->data = NULL; 123 } 124 125 static int devfreq_userspace_handler(struct devfreq *devfreq, 126 unsigned int event, void *data) 127 { 128 int ret = 0; 129 130 switch (event) { 131 case DEVFREQ_GOV_START: 132 ret = userspace_init(devfreq); 133 break; 134 case DEVFREQ_GOV_STOP: 135 userspace_exit(devfreq); 136 break; 137 default: 138 break; 139 } 140 141 return ret; 142 } 143 144 static struct devfreq_governor devfreq_userspace = { 145 .name = "userspace", 146 .get_target_freq = devfreq_userspace_func, 147 .event_handler = devfreq_userspace_handler, 148 }; 149 150 static int __init devfreq_userspace_init(void) 151 { 152 return devfreq_add_governor(&devfreq_userspace); 153 } 154 subsys_initcall(devfreq_userspace_init); 155 156 static void __exit devfreq_userspace_exit(void) 157 { 158 int ret; 159 160 ret = devfreq_remove_governor(&devfreq_userspace); 161 if (ret) 162 pr_err("%s: failed remove governor %d\n", __func__, ret); 163 164 return; 165 } 166 module_exit(devfreq_userspace_exit); 167 MODULE_LICENSE("GPL"); 168