drivers/leds/trigger/ledtrig-transient.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 //
   3 // LED Kernel Transient Trigger
   4 //
   5 // Transient trigger allows one shot timer activation. Please refer to
   6 // Documentation/leds/ledtrig-transient.txt for details
   7 // Copyright (C) 2012 Shuah Khan <shuahkhan@gmail.com>
   8 //
   9 // Based on Richard Purdie's ledtrig-timer.c and Atsushi Nemoto's
  10 // ledtrig-heartbeat.c
  11 // Design and use-case input from Jonas Bonn <jonas@southpole.se> and
  12 // Neil Brown <neilb@suse.de>
  13
  14 #include <linux/module.h>
  15 #include <linux/kernel.h>
  16 #include <linux/init.h>
  17 #include <linux/device.h>
  18 #include <linux/slab.h>
  19 #include <linux/timer.h>
  20 #include <linux/leds.h>
  21 #include "../leds.h"
  22
  23 struct transient_trig_data {
  24         int activate;
  25         int state;
  26         int restore_state;
  27         unsigned long duration;
  28         struct timer_list timer;
  29         struct led_classdev *led_cdev;
  30 };
  31
  32 static void transient_timer_function(struct timer_list *t)
  33 {
  34         struct transient_trig_data *transient_data =
  35                 from_timer(transient_data, t, timer);
  36         struct led_classdev *led_cdev = transient_data->led_cdev;
  37
  38         transient_data->activate = 0;
  39         led_set_brightness_nosleep(led_cdev, transient_data->restore_state);
  40 }
  41
  42 static ssize_t transient_activate_show(struct device *dev,
  43                 struct device_attribute *attr, char *buf)
  44 {
  45         struct led_classdev *led_cdev = dev_get_drvdata(dev);
  46         struct transient_trig_data *transient_data = led_cdev->trigger_data;
  47
  48         return sprintf(buf, "%d\n", transient_data->activate);
  49 }
  50
  51 static ssize_t transient_activate_store(struct device *dev,
  52                 struct device_attribute *attr, const char *buf, size_t size)
  53 {
  54         struct led_classdev *led_cdev = dev_get_drvdata(dev);
  55         struct transient_trig_data *transient_data = led_cdev->trigger_data;
  56         unsigned long state;
  57         ssize_t ret;
  58
  59         ret = kstrtoul(buf, 10, &state);
  60         if (ret)
  61                 return ret;
  62
  63         if (state != 1 && state != 0)
  64                 return -EINVAL;
  65
  66         /* cancel the running timer */
  67         if (state == 0 && transient_data->activate == 1) {
  68                 del_timer(&transient_data->timer);
  69                 transient_data->activate = state;
  70                 led_set_brightness_nosleep(led_cdev,
  71                                         transient_data->restore_state);
  72                 return size;
  73         }
  74
  75         /* start timer if there is no active timer */
  76         if (state == 1 && transient_data->activate == 0 &&
  77             transient_data->duration != 0) {
  78                 transient_data->activate = state;
  79                 led_set_brightness_nosleep(led_cdev, transient_data->state);
  80                 transient_data->restore_state =
  81                     (transient_data->state == LED_FULL) ? LED_OFF : LED_FULL;
  82                 mod_timer(&transient_data->timer,
  83                           jiffies + msecs_to_jiffies(transient_data->duration));
  84         }
  85
  86         /* state == 0 && transient_data->activate == 0
  87                 timer is not active - just return */
  88         /* state == 1 && transient_data->activate == 1
  89                 timer is already active - just return */
  90
  91         return size;
  92 }
  93
  94 static ssize_t transient_duration_show(struct device *dev,
  95                 struct device_attribute *attr, char *buf)
  96 {
  97         struct led_classdev *led_cdev = dev_get_drvdata(dev);
  98         struct transient_trig_data *transient_data = led_cdev->trigger_data;
  99
 100         return sprintf(buf, "%lu\n", transient_data->duration);
 101 }
 102
 103 static ssize_t transient_duration_store(struct device *dev,
 104                 struct device_attribute *attr, const char *buf, size_t size)
 105 {
 106         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 107         struct transient_trig_data *transient_data = led_cdev->trigger_data;
 108         unsigned long state;
 109         ssize_t ret;
 110
 111         ret = kstrtoul(buf, 10, &state);
 112         if (ret)
 113                 return ret;
 114
 115         transient_data->duration = state;
 116         return size;
 117 }
 118
 119 static ssize_t transient_state_show(struct device *dev,
 120                 struct device_attribute *attr, char *buf)
 121 {
 122         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 123         struct transient_trig_data *transient_data = led_cdev->trigger_data;
 124         int state;
 125
 126         state = (transient_data->state == LED_FULL) ? 1 : 0;
 127         return sprintf(buf, "%d\n", state);
 128 }
 129
 130 static ssize_t transient_state_store(struct device *dev,
 131                 struct device_attribute *attr, const char *buf, size_t size)
 132 {
 133         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 134         struct transient_trig_data *transient_data = led_cdev->trigger_data;
 135         unsigned long state;
 136         ssize_t ret;
 137
 138         ret = kstrtoul(buf, 10, &state);
 139         if (ret)
 140                 return ret;
 141
 142         if (state != 1 && state != 0)
 143                 return -EINVAL;
 144
 145         transient_data->state = (state == 1) ? LED_FULL : LED_OFF;
 146         return size;
 147 }
 148
 149 static DEVICE_ATTR(activate, 0644, transient_activate_show,
 150                    transient_activate_store);
 151 static DEVICE_ATTR(duration, 0644, transient_duration_show,
 152                    transient_duration_store);
 153 static DEVICE_ATTR(state, 0644, transient_state_show, transient_state_store);
 154
 155 static void transient_trig_activate(struct led_classdev *led_cdev)
 156 {
 157         int rc;
 158         struct transient_trig_data *tdata;
 159
 160         tdata = kzalloc(sizeof(struct transient_trig_data), GFP_KERNEL);
 161         if (!tdata) {
 162                 dev_err(led_cdev->dev,
 163                         "unable to allocate transient trigger\n");
 164                 return;
 165         }
 166         led_cdev->trigger_data = tdata;
 167         tdata->led_cdev = led_cdev;
 168
 169         rc = device_create_file(led_cdev->dev, &dev_attr_activate);
 170         if (rc)
 171                 goto err_out;
 172
 173         rc = device_create_file(led_cdev->dev, &dev_attr_duration);
 174         if (rc)
 175                 goto err_out_duration;
 176
 177         rc = device_create_file(led_cdev->dev, &dev_attr_state);
 178         if (rc)
 179                 goto err_out_state;
 180
 181         timer_setup(&tdata->timer, transient_timer_function, 0);
 182         led_cdev->activated = true;
 183
 184         return;
 185
 186 err_out_state:
 187         device_remove_file(led_cdev->dev, &dev_attr_duration);
 188 err_out_duration:
 189         device_remove_file(led_cdev->dev, &dev_attr_activate);
 190 err_out:
 191         dev_err(led_cdev->dev, "unable to register transient trigger\n");
 192         led_cdev->trigger_data = NULL;
 193         kfree(tdata);
 194 }
 195
 196 static void transient_trig_deactivate(struct led_classdev *led_cdev)
 197 {
 198         struct transient_trig_data *transient_data = led_cdev->trigger_data;
 199
 200         if (led_cdev->activated) {
 201                 del_timer_sync(&transient_data->timer);
 202                 led_set_brightness_nosleep(led_cdev,
 203                                         transient_data->restore_state);
 204                 device_remove_file(led_cdev->dev, &dev_attr_activate);
 205                 device_remove_file(led_cdev->dev, &dev_attr_duration);
 206                 device_remove_file(led_cdev->dev, &dev_attr_state);
 207                 led_cdev->trigger_data = NULL;
 208                 led_cdev->activated = false;
 209                 kfree(transient_data);
 210         }
 211 }
 212
 213 static struct led_trigger transient_trigger = {
 214         .name     = "transient",
 215         .activate = transient_trig_activate,
 216         .deactivate = transient_trig_deactivate,
 217 };
 218
 219 static int __init transient_trig_init(void)
 220 {
 221         return led_trigger_register(&transient_trigger);
 222 }
 223
 224 static void __exit transient_trig_exit(void)
 225 {
 226         led_trigger_unregister(&transient_trigger);
 227 }
 228
 229 module_init(transient_trig_init);
 230 module_exit(transient_trig_exit);
 231
 232 MODULE_AUTHOR("Shuah Khan <shuahkhan@gmail.com>");
 233 MODULE_DESCRIPTION("Transient LED trigger");
 234 MODULE_LICENSE("GPL v2");