drivers/devfreq/governor_userspace.c

   1 /*
   2  *  linux/drivers/devfreq/governor_simpleondemand.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 "governor.h"
  18
  19 struct userspace_data {
  20         unsigned long user_frequency;
  21         bool valid;
  22 };
  23
  24 static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq)
  25 {
  26         struct userspace_data *data = df->data;
  27
  28         if (data->valid) {
  29                 unsigned long adjusted_freq = data->user_frequency;
  30
  31                 if (df->max_freq && adjusted_freq > df->max_freq)
  32                         adjusted_freq = df->max_freq;
  33
  34                 if (df->min_freq && adjusted_freq < df->min_freq)
  35                         adjusted_freq = df->min_freq;
  36
  37                 *freq = adjusted_freq;
  38         } else {
  39                 *freq = df->previous_freq; /* No user freq specified yet */
  40         }
  41         return 0;
  42 }
  43
  44 static ssize_t store_freq(struct device *dev, struct device_attribute *attr,
  45                           const char *buf, size_t count)
  46 {
  47         struct devfreq *devfreq = to_devfreq(dev);
  48         struct userspace_data *data;
  49         unsigned long wanted;
  50         int err = 0;
  51
  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 struct attribute_group dev_attr_group = {
  90         .name   = "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         sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);
 115         kfree(devfreq->data);
 116         devfreq->data = NULL;
 117 }
 118
 119 const struct devfreq_governor devfreq_userspace = {
 120         .name = "userspace",
 121         .get_target_freq = devfreq_userspace_func,
 122         .init = userspace_init,
 123         .exit = userspace_exit,
 124         .no_central_polling = true,
 125 };