drivers/leds/ledtrig-transient.c

   1 /*
   2  * LED Kernel Transient Trigger
   3  *
   4  * Copyright (C) 2012 Shuah Khan <shuahkhan@gmail.com>
   5  *
   6  * Based on Richard Purdie's ledtrig-timer.c and Atsushi Nemoto's
   7  * ledtrig-heartbeat.c
   8  * Design and use-case input from Jonas Bonn <jonas@southpole.se> and
   9  * Neil Brown <neilb@suse.de>
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License version 2 as
  13  * published by the Free Software Foundation.
  14  *
  15  */
  16 /*
  17  * Transient trigger allows one shot timer activation. Please refer to
  18  * Documentation/leds/ledtrig-transient.txt for details
  19 */
  20
  21 #include <linux/module.h>
  22 #include <linux/kernel.h>
  23 #include <linux/init.h>
  24 #include <linux/device.h>
  25 #include <linux/slab.h>
  26 #include <linux/timer.h>
  27 #include <linux/leds.h>
  28 #include "leds.h"
  29
  30 struct transient_trig_data {
  31         int activate;
  32         int state;
  33         int restore_state;
  34         unsigned long duration;
  35         struct timer_list timer;
  36 };
  37
  38 static void transient_timer_function(unsigned long data)
  39 {
  40         struct led_classdev *led_cdev = (struct led_classdev *) data;
  41         struct transient_trig_data *transient_data = led_cdev->trigger_data;
  42
  43         transient_data->activate = 0;
  44         __led_set_brightness(led_cdev, transient_data->restore_state);
  45 }
  46
  47 static ssize_t transient_activate_show(struct device *dev,
  48                 struct device_attribute *attr, char *buf)
  49 {
  50         struct led_classdev *led_cdev = dev_get_drvdata(dev);
  51         struct transient_trig_data *transient_data = led_cdev->trigger_data;
  52
  53         return sprintf(buf, "%d\n", transient_data->activate);
  54 }
  55
  56 static ssize_t transient_activate_store(struct device *dev,
  57                 struct device_attribute *attr, const char *buf, size_t size)
  58 {
  59         struct led_classdev *led_cdev = dev_get_drvdata(dev);
  60         struct transient_trig_data *transient_data = led_cdev->trigger_data;
  61         unsigned long state;
  62         ssize_t ret;
  63
  64         ret = kstrtoul(buf, 10, &state);
  65         if (ret)
  66                 return ret;
  67
  68         if (state != 1 && state != 0)
  69                 return -EINVAL;
  70
  71         /* cancel the running timer */
  72         if (state == 0 && transient_data->activate == 1) {
  73                 del_timer(&transient_data->timer);
  74                 transient_data->activate = state;
  75                 __led_set_brightness(led_cdev, transient_data->restore_state);
  76                 return size;
  77         }
  78
  79         /* start timer if there is no active timer */
  80         if (state == 1 && transient_data->activate == 0 &&
  81             transient_data->duration != 0) {
  82                 transient_data->activate = state;
  83                 __led_set_brightness(led_cdev, transient_data->state);
  84                 transient_data->restore_state =
  85                     (transient_data->state == LED_FULL) ? LED_OFF : LED_FULL;
  86                 mod_timer(&transient_data->timer,
  87                           jiffies + transient_data->duration);
  88         }
  89
  90         /* state == 0 && transient_data->activate == 0
  91                 timer is not active - just return */
  92         /* state == 1 && transient_data->activate == 1
  93                 timer is already active - just return */
  94
  95         return size;
  96 }
  97
  98 static ssize_t transient_duration_show(struct device *dev,
  99                 struct device_attribute *attr, char *buf)
 100 {
 101         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 102         struct transient_trig_data *transient_data = led_cdev->trigger_data;
 103
 104         return sprintf(buf, "%lu\n", transient_data->duration);
 105 }
 106
 107 static ssize_t transient_duration_store(struct device *dev,
 108                 struct device_attribute *attr, const char *buf, size_t size)
 109 {
 110         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 111         struct transient_trig_data *transient_data = led_cdev->trigger_data;
 112         unsigned long state;
 113         ssize_t ret;
 114
 115         ret = kstrtoul(buf, 10, &state);
 116         if (ret)
 117                 return ret;
 118
 119         transient_data->duration = state;
 120         return size;
 121 }
 122
 123 static ssize_t transient_state_show(struct device *dev,
 124                 struct device_attribute *attr, char *buf)
 125 {
 126         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 127         struct transient_trig_data *transient_data = led_cdev->trigger_data;
 128         int state;
 129
 130         state = (transient_data->state == LED_FULL) ? 1 : 0;
 131         return sprintf(buf, "%d\n", state);
 132 }
 133
 134 static ssize_t transient_state_store(struct device *dev,
 135                 struct device_attribute *attr, const char *buf, size_t size)
 136 {
 137         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 138         struct transient_trig_data *transient_data = led_cdev->trigger_data;
 139         unsigned long state;
 140         ssize_t ret;
 141
 142         ret = kstrtoul(buf, 10, &state);
 143         if (ret)
 144                 return ret;
 145
 146         if (state != 1 && state != 0)
 147                 return -EINVAL;
 148
 149         transient_data->state = (state == 1) ? LED_FULL : LED_OFF;
 150         return size;
 151 }
 152
 153 static DEVICE_ATTR(activate, 0644, transient_activate_show,
 154                    transient_activate_store);
 155 static DEVICE_ATTR(duration, 0644, transient_duration_show,
 156                    transient_duration_store);
 157 static DEVICE_ATTR(state, 0644, transient_state_show, transient_state_store);
 158
 159 static void transient_trig_activate(struct led_classdev *led_cdev)
 160 {
 161         int rc;
 162         struct transient_trig_data *tdata;
 163
 164         tdata = kzalloc(sizeof(struct transient_trig_data), GFP_KERNEL);
 165         if (!tdata) {
 166                 dev_err(led_cdev->dev,
 167                         "unable to allocate transient trigger\n");
 168                 return;
 169         }
 170         led_cdev->trigger_data = tdata;
 171
 172         rc = device_create_file(led_cdev->dev, &dev_attr_activate);
 173         if (rc)
 174                 goto err_out;
 175
 176         rc = device_create_file(led_cdev->dev, &dev_attr_duration);
 177         if (rc)
 178                 goto err_out_duration;
 179
 180         rc = device_create_file(led_cdev->dev, &dev_attr_state);
 181         if (rc)
 182                 goto err_out_state;
 183
 184         setup_timer(&tdata->timer, transient_timer_function,
 185                     (unsigned long) led_cdev);
 186         led_cdev->activated = true;
 187
 188         return;
 189
 190 err_out_state:
 191         device_remove_file(led_cdev->dev, &dev_attr_duration);
 192 err_out_duration:
 193         device_remove_file(led_cdev->dev, &dev_attr_activate);
 194 err_out:
 195         dev_err(led_cdev->dev, "unable to register transient trigger\n");
 196         led_cdev->trigger_data = NULL;
 197         kfree(tdata);
 198 }
 199
 200 static void transient_trig_deactivate(struct led_classdev *led_cdev)
 201 {
 202         struct transient_trig_data *transient_data = led_cdev->trigger_data;
 203
 204         if (led_cdev->activated) {
 205                 del_timer_sync(&transient_data->timer);
 206                 __led_set_brightness(led_cdev, transient_data->restore_state);
 207                 device_remove_file(led_cdev->dev, &dev_attr_activate);
 208                 device_remove_file(led_cdev->dev, &dev_attr_duration);
 209                 device_remove_file(led_cdev->dev, &dev_attr_state);
 210                 led_cdev->trigger_data = NULL;
 211                 led_cdev->activated = false;
 212                 kfree(transient_data);
 213         }
 214 }
 215
 216 static struct led_trigger transient_trigger = {
 217         .name     = "transient",
 218         .activate = transient_trig_activate,
 219         .deactivate = transient_trig_deactivate,
 220 };
 221
 222 static int __init transient_trig_init(void)
 223 {
 224         return led_trigger_register(&transient_trigger);
 225 }
 226
 227 static void __exit transient_trig_exit(void)
 228 {
 229         led_trigger_unregister(&transient_trigger);
 230 }
 231
 232 module_init(transient_trig_init);
 233 module_exit(transient_trig_exit);
 234
 235 MODULE_AUTHOR("Shuah Khan <shuahkhan@gmail.com>");
 236 MODULE_DESCRIPTION("Transient LED trigger");
 237 MODULE_LICENSE("GPL");