drivers/leds/trigger/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_async(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_async(led_cdev,
  76                                         transient_data->restore_state);
  77                 return size;
  78         }
  79
  80         /* start timer if there is no active timer */
  81         if (state == 1 && transient_data->activate == 0 &&
  82             transient_data->duration != 0) {
  83                 transient_data->activate = state;
  84                 led_set_brightness_async(led_cdev, transient_data->state);
  85                 transient_data->restore_state =
  86                     (transient_data->state == LED_FULL) ? LED_OFF : LED_FULL;
  87                 mod_timer(&transient_data->timer,
  88                           jiffies + transient_data->duration);
  89         }
  90
  91         /* state == 0 && transient_data->activate == 0
  92                 timer is not active - just return */
  93         /* state == 1 && transient_data->activate == 1
  94                 timer is already active - just return */
  95
  96         return size;
  97 }
  98
  99 static ssize_t transient_duration_show(struct device *dev,
 100                 struct device_attribute *attr, char *buf)
 101 {
 102         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 103         struct transient_trig_data *transient_data = led_cdev->trigger_data;
 104
 105         return sprintf(buf, "%lu\n", transient_data->duration);
 106 }
 107
 108 static ssize_t transient_duration_store(struct device *dev,
 109                 struct device_attribute *attr, const char *buf, size_t size)
 110 {
 111         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 112         struct transient_trig_data *transient_data = led_cdev->trigger_data;
 113         unsigned long state;
 114         ssize_t ret;
 115
 116         ret = kstrtoul(buf, 10, &state);
 117         if (ret)
 118                 return ret;
 119
 120         transient_data->duration = state;
 121         return size;
 122 }
 123
 124 static ssize_t transient_state_show(struct device *dev,
 125                 struct device_attribute *attr, char *buf)
 126 {
 127         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 128         struct transient_trig_data *transient_data = led_cdev->trigger_data;
 129         int state;
 130
 131         state = (transient_data->state == LED_FULL) ? 1 : 0;
 132         return sprintf(buf, "%d\n", state);
 133 }
 134
 135 static ssize_t transient_state_store(struct device *dev,
 136                 struct device_attribute *attr, const char *buf, size_t size)
 137 {
 138         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 139         struct transient_trig_data *transient_data = led_cdev->trigger_data;
 140         unsigned long state;
 141         ssize_t ret;
 142
 143         ret = kstrtoul(buf, 10, &state);
 144         if (ret)
 145                 return ret;
 146
 147         if (state != 1 && state != 0)
 148                 return -EINVAL;
 149
 150         transient_data->state = (state == 1) ? LED_FULL : LED_OFF;
 151         return size;
 152 }
 153
 154 static DEVICE_ATTR(activate, 0644, transient_activate_show,
 155                    transient_activate_store);
 156 static DEVICE_ATTR(duration, 0644, transient_duration_show,
 157                    transient_duration_store);
 158 static DEVICE_ATTR(state, 0644, transient_state_show, transient_state_store);
 159
 160 static void transient_trig_activate(struct led_classdev *led_cdev)
 161 {
 162         int rc;
 163         struct transient_trig_data *tdata;
 164
 165         tdata = kzalloc(sizeof(struct transient_trig_data), GFP_KERNEL);
 166         if (!tdata) {
 167                 dev_err(led_cdev->dev,
 168                         "unable to allocate transient trigger\n");
 169                 return;
 170         }
 171         led_cdev->trigger_data = tdata;
 172
 173         rc = device_create_file(led_cdev->dev, &dev_attr_activate);
 174         if (rc)
 175                 goto err_out;
 176
 177         rc = device_create_file(led_cdev->dev, &dev_attr_duration);
 178         if (rc)
 179                 goto err_out_duration;
 180
 181         rc = device_create_file(led_cdev->dev, &dev_attr_state);
 182         if (rc)
 183                 goto err_out_state;
 184
 185         setup_timer(&tdata->timer, transient_timer_function,
 186                     (unsigned long) led_cdev);
 187         led_cdev->activated = true;
 188
 189         return;
 190
 191 err_out_state:
 192         device_remove_file(led_cdev->dev, &dev_attr_duration);
 193 err_out_duration:
 194         device_remove_file(led_cdev->dev, &dev_attr_activate);
 195 err_out:
 196         dev_err(led_cdev->dev, "unable to register transient trigger\n");
 197         led_cdev->trigger_data = NULL;
 198         kfree(tdata);
 199 }
 200
 201 static void transient_trig_deactivate(struct led_classdev *led_cdev)
 202 {
 203         struct transient_trig_data *transient_data = led_cdev->trigger_data;
 204
 205         if (led_cdev->activated) {
 206                 del_timer_sync(&transient_data->timer);
 207                 led_set_brightness_async(led_cdev,
 208                                         transient_data->restore_state);
 209                 device_remove_file(led_cdev->dev, &dev_attr_activate);
 210                 device_remove_file(led_cdev->dev, &dev_attr_duration);
 211                 device_remove_file(led_cdev->dev, &dev_attr_state);
 212                 led_cdev->trigger_data = NULL;
 213                 led_cdev->activated = false;
 214                 kfree(transient_data);
 215         }
 216 }
 217
 218 static struct led_trigger transient_trigger = {
 219         .name     = "transient",
 220         .activate = transient_trig_activate,
 221         .deactivate = transient_trig_deactivate,
 222 };
 223
 224 static int __init transient_trig_init(void)
 225 {
 226         return led_trigger_register(&transient_trigger);
 227 }
 228
 229 static void __exit transient_trig_exit(void)
 230 {
 231         led_trigger_unregister(&transient_trigger);
 232 }
 233
 234 module_init(transient_trig_init);
 235 module_exit(transient_trig_exit);
 236
 237 MODULE_AUTHOR("Shuah Khan <shuahkhan@gmail.com>");
 238 MODULE_DESCRIPTION("Transient LED trigger");
 239 MODULE_LICENSE("GPL");