// 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 =
                timer_container_of(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) {
                timer_delete(&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_obj(struct transient_trig_data);
        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);

        timer_shutdown_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");