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// SPDX-License-Identifier: GPL-2.0
//
// LED Kernel Transient Trigger
//
// Transient trigger allows one shot timer activation. Please refer to
// Documentation/leds/ledtrig-transient.rst for details
// Copyright (C) 2012 Shuah Khan <shuahkhan@gmail.com>
//
// Based on Richard Purdie's ledtrig-timer.c and Atsushi Nemoto's
// ledtrig-heartbeat.c
// Design and use-case input from Jonas Bonn <jonas@southpole.se> and
// Neil Brown <neilb@suse.de>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/timer.h>
#include <linux/leds.h>
#include "../leds.h"
struct transient_trig_data {
int activate;
int state;
int restore_state;
unsigned long duration;
struct timer_list timer;
struct led_classdev *led_cdev;
};
static void transient_timer_function(struct timer_list *t)
{
struct transient_trig_data *transient_data =
from_timer(transient_data, t, timer);
struct led_classdev *led_cdev = transient_data->led_cdev;
transient_data->activate = 0;
led_set_brightness_nosleep(led_cdev, transient_data->restore_state);
}
static ssize_t transient_activate_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct transient_trig_data *transient_data =
led_trigger_get_drvdata(dev);
return sprintf(buf, "%d\n", transient_data->activate);
}
static ssize_t transient_activate_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t size)
{
struct led_classdev *led_cdev = led_trigger_get_led(dev);
struct transient_trig_data *transient_data =
led_trigger_get_drvdata(dev);
unsigned long state;
ssize_t ret;
ret = kstrtoul(buf, 10, &state);
if (ret)
return ret;
if (state != 1 && state != 0)
return -EINVAL;
/* cancel the running timer */
if (state == 0 && transient_data->activate == 1) {
del_timer(&transient_data->timer);
transient_data->activate = state;
led_set_brightness_nosleep(led_cdev,
transient_data->restore_state);
return size;
}
/* start timer if there is no active timer */
if (state == 1 && transient_data->activate == 0 &&
transient_data->duration != 0) {
transient_data->activate = state;
led_set_brightness_nosleep(led_cdev, transient_data->state);
transient_data->restore_state =
(transient_data->state == LED_FULL) ? LED_OFF : LED_FULL;
mod_timer(&transient_data->timer,
jiffies + msecs_to_jiffies(transient_data->duration));
}
/* state == 0 && transient_data->activate == 0
timer is not active - just return */
/* state == 1 && transient_data->activate == 1
timer is already active - just return */
return size;
}
static ssize_t transient_duration_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct transient_trig_data *transient_data = led_trigger_get_drvdata(dev);
return sprintf(buf, "%lu\n", transient_data->duration);
}
static ssize_t transient_duration_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t size)
{
struct transient_trig_data *transient_data =
led_trigger_get_drvdata(dev);
unsigned long state;
ssize_t ret;
ret = kstrtoul(buf, 10, &state);
if (ret)
return ret;
transient_data->duration = state;
return size;
}
static ssize_t transient_state_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct transient_trig_data *transient_data =
led_trigger_get_drvdata(dev);
int state;
state = (transient_data->state == LED_FULL) ? 1 : 0;
return sprintf(buf, "%d\n", state);
}
static ssize_t transient_state_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t size)
{
struct transient_trig_data *transient_data =
led_trigger_get_drvdata(dev);
unsigned long state;
ssize_t ret;
ret = kstrtoul(buf, 10, &state);
if (ret)
return ret;
if (state != 1 && state != 0)
return -EINVAL;
transient_data->state = (state == 1) ? LED_FULL : LED_OFF;
return size;
}
static DEVICE_ATTR(activate, 0644, transient_activate_show,
transient_activate_store);
static DEVICE_ATTR(duration, 0644, transient_duration_show,
transient_duration_store);
static DEVICE_ATTR(state, 0644, transient_state_show, transient_state_store);
static struct attribute *transient_trig_attrs[] = {
&dev_attr_activate.attr,
&dev_attr_duration.attr,
&dev_attr_state.attr,
NULL
};
ATTRIBUTE_GROUPS(transient_trig);
static int transient_trig_activate(struct led_classdev *led_cdev)
{
struct transient_trig_data *tdata;
tdata = kzalloc(sizeof(struct transient_trig_data), GFP_KERNEL);
if (!tdata)
return -ENOMEM;
led_set_trigger_data(led_cdev, tdata);
tdata->led_cdev = led_cdev;
timer_setup(&tdata->timer, transient_timer_function, 0);
return 0;
}
static void transient_trig_deactivate(struct led_classdev *led_cdev)
{
struct transient_trig_data *transient_data = led_get_trigger_data(led_cdev);
del_timer_sync(&transient_data->timer);
led_set_brightness_nosleep(led_cdev, transient_data->restore_state);
kfree(transient_data);
}
static struct led_trigger transient_trigger = {
.name = "transient",
.activate = transient_trig_activate,
.deactivate = transient_trig_deactivate,
.groups = transient_trig_groups,
};
module_led_trigger(transient_trigger);
MODULE_AUTHOR("Shuah Khan <shuahkhan@gmail.com>");
MODULE_DESCRIPTION("Transient LED trigger");
MODULE_LICENSE("GPL v2");
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