// SPDX-License-Identifier: GPL-2.0-only
/*
 * LED Heartbeat Trigger
 *
 * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
 *
 * Based on Richard Purdie's ledtrig-timer.c and some arch's
 * CONFIG_HEARTBEAT code.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/panic_notifier.h>
#include <linux/slab.h>
#include <linux/timer.h>
#include <linux/sched.h>
#include <linux/sched/loadavg.h>
#include <linux/leds.h>
#include <linux/reboot.h>
#include "../leds.h"

static int panic_heartbeats;

struct heartbeat_trig_data {
        struct led_classdev *led_cdev;
        unsigned int phase;
        unsigned int period;
        struct timer_list timer;
        unsigned int invert;
};

static void led_heartbeat_function(struct timer_list *t)
{
        struct heartbeat_trig_data *heartbeat_data =
                timer_container_of(heartbeat_data, t, timer);
        struct led_classdev *led_cdev;
        unsigned long brightness = LED_OFF;
        unsigned long delay = 0;

        led_cdev = heartbeat_data->led_cdev;

        if (unlikely(panic_heartbeats)) {
                led_set_brightness_nosleep(led_cdev, LED_OFF);
                return;
        }

        if (test_and_clear_bit(LED_BLINK_BRIGHTNESS_CHANGE, &led_cdev->work_flags))
                led_cdev->blink_brightness = led_cdev->new_blink_brightness;

        /* acts like an actual heart beat -- ie thump-thump-pause... */
        switch (heartbeat_data->phase) {
        case 0:
                /*
                 * The hyperbolic function below modifies the
                 * heartbeat period length in dependency of the
                 * current (1min) load. It goes through the points
                 * f(0)=1260, f(1)=860, f(5)=510, f(inf)->300.
                 */
                heartbeat_data->period = 300 +
                        (6720 << FSHIFT) / (5 * avenrun[0] + (7 << FSHIFT));
                heartbeat_data->period =
                        msecs_to_jiffies(heartbeat_data->period);
                delay = msecs_to_jiffies(70);
                heartbeat_data->phase++;
                if (!heartbeat_data->invert)
                        brightness = led_cdev->blink_brightness;
                break;
        case 1:
                delay = heartbeat_data->period / 4 - msecs_to_jiffies(70);
                heartbeat_data->phase++;
                if (heartbeat_data->invert)
                        brightness = led_cdev->blink_brightness;
                break;
        case 2:
                delay = msecs_to_jiffies(70);
                heartbeat_data->phase++;
                if (!heartbeat_data->invert)
                        brightness = led_cdev->blink_brightness;
                break;
        default:
                delay = heartbeat_data->period - heartbeat_data->period / 4 -
                        msecs_to_jiffies(70);
                heartbeat_data->phase = 0;
                if (heartbeat_data->invert)
                        brightness = led_cdev->blink_brightness;
                break;
        }

        led_set_brightness_nosleep(led_cdev, brightness);
        mod_timer(&heartbeat_data->timer, jiffies + delay);
}

static ssize_t led_invert_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct heartbeat_trig_data *heartbeat_data =
                led_trigger_get_drvdata(dev);

        return sprintf(buf, "%u\n", heartbeat_data->invert);
}

static ssize_t led_invert_store(struct device *dev,
                struct device_attribute *attr, const char *buf, size_t size)
{
        struct heartbeat_trig_data *heartbeat_data =
                led_trigger_get_drvdata(dev);
        unsigned long state;
        int ret;

        ret = kstrtoul(buf, 0, &state);
        if (ret)
                return ret;

        heartbeat_data->invert = !!state;

        return size;
}

static DEVICE_ATTR(invert, 0644, led_invert_show, led_invert_store);

static struct attribute *heartbeat_trig_attrs[] = {
        &dev_attr_invert.attr,
        NULL
};
ATTRIBUTE_GROUPS(heartbeat_trig);

static int heartbeat_trig_activate(struct led_classdev *led_cdev)
{
        struct heartbeat_trig_data *heartbeat_data;

        heartbeat_data = kzalloc_obj(*heartbeat_data);
        if (!heartbeat_data)
                return -ENOMEM;

        led_set_trigger_data(led_cdev, heartbeat_data);
        heartbeat_data->led_cdev = led_cdev;

        timer_setup(&heartbeat_data->timer, led_heartbeat_function, 0);
        heartbeat_data->phase = 0;
        if (!led_cdev->blink_brightness)
                led_cdev->blink_brightness = led_cdev->max_brightness;
        led_heartbeat_function(&heartbeat_data->timer);
        set_bit(LED_BLINK_SW, &led_cdev->work_flags);

        return 0;
}

static void heartbeat_trig_deactivate(struct led_classdev *led_cdev)
{
        struct heartbeat_trig_data *heartbeat_data =
                led_get_trigger_data(led_cdev);

        timer_shutdown_sync(&heartbeat_data->timer);
        kfree(heartbeat_data);
        clear_bit(LED_BLINK_SW, &led_cdev->work_flags);
}

static struct led_trigger heartbeat_led_trigger = {
        .name     = "heartbeat",
        .activate = heartbeat_trig_activate,
        .deactivate = heartbeat_trig_deactivate,
        .groups = heartbeat_trig_groups,
};

static int heartbeat_reboot_notifier(struct notifier_block *nb,
                                     unsigned long code, void *unused)
{
        led_trigger_unregister(&heartbeat_led_trigger);
        return NOTIFY_DONE;
}

static int heartbeat_panic_notifier(struct notifier_block *nb,
                                     unsigned long code, void *unused)
{
        panic_heartbeats = 1;
        return NOTIFY_DONE;
}

static struct notifier_block heartbeat_reboot_nb = {
        .notifier_call = heartbeat_reboot_notifier,
};

static struct notifier_block heartbeat_panic_nb = {
        .notifier_call = heartbeat_panic_notifier,
};

static int __init heartbeat_trig_init(void)
{
        int rc = led_trigger_register(&heartbeat_led_trigger);

        if (!rc) {
                atomic_notifier_chain_register(&panic_notifier_list,
                                               &heartbeat_panic_nb);
                register_reboot_notifier(&heartbeat_reboot_nb);
        }
        return rc;
}

static void __exit heartbeat_trig_exit(void)
{
        unregister_reboot_notifier(&heartbeat_reboot_nb);
        atomic_notifier_chain_unregister(&panic_notifier_list,
                                         &heartbeat_panic_nb);
        led_trigger_unregister(&heartbeat_led_trigger);
}

module_init(heartbeat_trig_init);
module_exit(heartbeat_trig_exit);

MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
MODULE_DESCRIPTION("Heartbeat LED trigger");
MODULE_LICENSE("GPL v2");