/*
 * LED Kernel Transient Trigger
 *
 * 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>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */
/*
 * Transient trigger allows one shot timer activation. Please refer to
 * Documentation/leds/ledtrig-transient.txt for details
*/

#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;
};

static void transient_timer_function(unsigned long data)
{
        struct led_classdev *led_cdev = (struct led_classdev *) data;
        struct transient_trig_data *transient_data = led_cdev->trigger_data;

        transient_data->activate = 0;
        __led_set_brightness(led_cdev, transient_data->restore_state);
}

static ssize_t transient_activate_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct led_classdev *led_cdev = dev_get_drvdata(dev);
        struct transient_trig_data *transient_data = led_cdev->trigger_data;

        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 = dev_get_drvdata(dev);
        struct transient_trig_data *transient_data = led_cdev->trigger_data;
        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(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(led_cdev, transient_data->state);
                transient_data->restore_state =
                    (transient_data->state == LED_FULL) ? LED_OFF : LED_FULL;
                mod_timer(&transient_data->timer,
                          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 led_classdev *led_cdev = dev_get_drvdata(dev);
        struct transient_trig_data *transient_data = led_cdev->trigger_data;

        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 led_classdev *led_cdev = dev_get_drvdata(dev);
        struct transient_trig_data *transient_data = led_cdev->trigger_data;
        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 led_classdev *led_cdev = dev_get_drvdata(dev);
        struct transient_trig_data *transient_data = led_cdev->trigger_data;
        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 led_classdev *led_cdev = dev_get_drvdata(dev);
        struct transient_trig_data *transient_data = led_cdev->trigger_data;
        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 void transient_trig_activate(struct led_classdev *led_cdev)
{
        int rc;
        struct transient_trig_data *tdata;

        tdata = kzalloc(sizeof(struct transient_trig_data), GFP_KERNEL);
        if (!tdata) {
                dev_err(led_cdev->dev,
                        "unable to allocate transient trigger\n");
                return;
        }
        led_cdev->trigger_data = tdata;

        rc = device_create_file(led_cdev->dev, &dev_attr_activate);
        if (rc)
                goto err_out;

        rc = device_create_file(led_cdev->dev, &dev_attr_duration);
        if (rc)
                goto err_out_duration;

        rc = device_create_file(led_cdev->dev, &dev_attr_state);
        if (rc)
                goto err_out_state;

        setup_timer(&tdata->timer, transient_timer_function,
                    (unsigned long) led_cdev);
        led_cdev->activated = true;

        return;

err_out_state:
        device_remove_file(led_cdev->dev, &dev_attr_duration);
err_out_duration:
        device_remove_file(led_cdev->dev, &dev_attr_activate);
err_out:
        dev_err(led_cdev->dev, "unable to register transient trigger\n");
        led_cdev->trigger_data = NULL;
        kfree(tdata);
}

static void transient_trig_deactivate(struct led_classdev *led_cdev)
{
        struct transient_trig_data *transient_data = led_cdev->trigger_data;

        if (led_cdev->activated) {
                del_timer_sync(&transient_data->timer);
                __led_set_brightness(led_cdev, transient_data->restore_state);
                device_remove_file(led_cdev->dev, &dev_attr_activate);
                device_remove_file(led_cdev->dev, &dev_attr_duration);
                device_remove_file(led_cdev->dev, &dev_attr_state);
                led_cdev->trigger_data = NULL;
                led_cdev->activated = false;
                kfree(transient_data);
        }
}

static struct led_trigger transient_trigger = {
        .name     = "transient",
        .activate = transient_trig_activate,
        .deactivate = transient_trig_deactivate,
};

static int __init transient_trig_init(void)
{
        return led_trigger_register(&transient_trigger);
}

static void __exit transient_trig_exit(void)
{
        led_trigger_unregister(&transient_trigger);
}

module_init(transient_trig_init);
module_exit(transient_trig_exit);

MODULE_AUTHOR("Shuah Khan <shuahkhan@gmail.com>");
MODULE_DESCRIPTION("Transient LED trigger");
MODULE_LICENSE("GPL");