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                 *freq = df->previous_freq; /* No user freq specified yet */
  30         else
  31                 *freq = data->user_frequency;
  32         return 0;
  33 }
  34
  35 static ssize_t store_freq(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
  44         mutex_lock(&devfreq->lock);
  45         data = devfreq->data;
  46
  47         sscanf(buf, "%lu", &wanted);
  48         data->user_frequency = wanted;
  49         data->valid = true;
  50         err = update_devfreq(devfreq);
  51         if (err == 0)
  52                 err = count;
  53         mutex_unlock(&devfreq->lock);
  54         return err;
  55 }
  56
  57 static ssize_t show_freq(struct device *dev, struct device_attribute *attr,
  58                          char *buf)
  59 {
  60         struct devfreq *devfreq = to_devfreq(dev);
  61         struct userspace_data *data;
  62         int err = 0;
  63
  64         mutex_lock(&devfreq->lock);
  65         data = devfreq->data;
  66
  67         if (data->valid)
  68                 err = sprintf(buf, "%lu\n", data->user_frequency);
  69         else
  70                 err = sprintf(buf, "undefined\n");
  71         mutex_unlock(&devfreq->lock);
  72         return err;
  73 }
  74
  75 static DEVICE_ATTR(set_freq, 0644, show_freq, store_freq);
  76 static struct attribute *dev_entries[] = {
  77         &dev_attr_set_freq.attr,
  78         NULL,
  79 };
  80 static struct attribute_group dev_attr_group = {
  81         .name   = "userspace",
  82         .attrs  = dev_entries,
  83 };
  84
  85 static int userspace_init(struct devfreq *devfreq)
  86 {
  87         int err = 0;
  88         struct userspace_data *data = kzalloc(sizeof(struct userspace_data),
  89                                               GFP_KERNEL);
  90
  91         if (!data) {
  92                 err = -ENOMEM;
  93                 goto out;
  94         }
  95         data->valid = false;
  96         devfreq->data = data;
  97
  98         err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);
  99 out:
 100         return err;
 101 }
 102
 103 static void userspace_exit(struct devfreq *devfreq)
 104 {
 105         sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);
 106         kfree(devfreq->data);
 107         devfreq->data = NULL;
 108 }
 109
 110 const struct devfreq_governor devfreq_userspace = {
 111         .name = "userspace",
 112         .get_target_freq = devfreq_userspace_func,
 113         .init = userspace_init,
 114         .exit = userspace_exit,
 115         .no_central_polling = true,
 116 };