// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2020 Intel Corporation
 * Author: Johannes Berg <johannes@sipsolutions.net>
 */
#include <linux/platform_device.h>
#include <linux/time-internal.h>
#include <linux/suspend.h>
#include <linux/err.h>
#include <linux/rtc.h>
#include <kern_util.h>
#include <irq_kern.h>
#include <os.h>
#include "rtc.h"

static time64_t uml_rtc_alarm_time;
static bool uml_rtc_alarm_enabled;
static struct rtc_device *uml_rtc;
static int uml_rtc_irq_fd, uml_rtc_irq;

#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT

static void uml_rtc_time_travel_alarm(struct time_travel_event *ev)
{
        uml_rtc_send_timetravel_alarm();
}

static struct time_travel_event uml_rtc_alarm_event = {
        .fn = uml_rtc_time_travel_alarm,
};
#endif

static int uml_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        struct timespec64 ts;

        /* Use this to get correct time in time-travel mode */
        read_persistent_clock64(&ts);
        rtc_time64_to_tm(timespec64_to_ktime(ts) / NSEC_PER_SEC, tm);

        return 0;
}

static int uml_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        rtc_time64_to_tm(uml_rtc_alarm_time, &alrm->time);
        alrm->enabled = uml_rtc_alarm_enabled;

        return 0;
}

static int uml_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
{
        struct timespec64 ts;
        unsigned long long secs;

        if (!enable && !uml_rtc_alarm_enabled)
                return 0;

        uml_rtc_alarm_enabled = enable;

        read_persistent_clock64(&ts);
        secs = uml_rtc_alarm_time - ts.tv_sec;

        if (time_travel_mode == TT_MODE_OFF) {
                if (!enable) {
                        uml_rtc_disable_alarm();
                        return 0;
                }

                /* enable or update */
                return uml_rtc_enable_alarm(secs);
        } else {
                time_travel_del_event(&uml_rtc_alarm_event);

                if (enable)
                        time_travel_add_event_rel(&uml_rtc_alarm_event,
                                                  secs * NSEC_PER_SEC -
                                                  ts.tv_nsec);
        }

        return 0;
}

static int uml_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        uml_rtc_alarm_irq_enable(dev, 0);
        uml_rtc_alarm_time = rtc_tm_to_time64(&alrm->time);
        uml_rtc_alarm_irq_enable(dev, alrm->enabled);

        return 0;
}

static const struct rtc_class_ops uml_rtc_ops = {
        .read_time = uml_rtc_read_time,
        .read_alarm = uml_rtc_read_alarm,
        .alarm_irq_enable = uml_rtc_alarm_irq_enable,
        .set_alarm = uml_rtc_set_alarm,
};

static irqreturn_t uml_rtc_interrupt(int irq, void *data)
{
        unsigned long long c = 0;

        /* alarm triggered, it's now off */
        uml_rtc_alarm_enabled = false;

        os_read_file(uml_rtc_irq_fd, &c, sizeof(c));
        WARN_ON(c == 0);

        pm_system_wakeup();
        rtc_update_irq(uml_rtc, 1, RTC_IRQF | RTC_AF);

        return IRQ_HANDLED;
}

static int uml_rtc_setup(void)
{
        int err;

        err = uml_rtc_start(time_travel_mode != TT_MODE_OFF);
        if (WARN(err < 0, "err = %d\n", err))
                return err;

        uml_rtc_irq_fd = err;

        err = um_request_irq(UM_IRQ_ALLOC, uml_rtc_irq_fd, IRQ_READ,
                             uml_rtc_interrupt, 0, "rtc", NULL);
        if (err < 0) {
                uml_rtc_stop(time_travel_mode != TT_MODE_OFF);
                return err;
        }

        irq_set_irq_wake(err, 1);

        uml_rtc_irq = err;
        return 0;
}

static void uml_rtc_cleanup(void)
{
        um_free_irq(uml_rtc_irq, NULL);
        uml_rtc_stop(time_travel_mode != TT_MODE_OFF);
}

static int uml_rtc_probe(struct platform_device *pdev)
{
        int err;

        err = uml_rtc_setup();
        if (err)
                return err;

        uml_rtc = devm_rtc_allocate_device(&pdev->dev);
        if (IS_ERR(uml_rtc)) {
                err = PTR_ERR(uml_rtc);
                goto cleanup;
        }

        uml_rtc->ops = &uml_rtc_ops;

        device_init_wakeup(&pdev->dev, 1);

        err = devm_rtc_register_device(uml_rtc);
        if (err)
                goto cleanup;

        return 0;
cleanup:
        uml_rtc_cleanup();
        return err;
}

static void uml_rtc_remove(struct platform_device *pdev)
{
        device_init_wakeup(&pdev->dev, 0);
        uml_rtc_cleanup();
}

static struct platform_driver uml_rtc_driver = {
        .probe = uml_rtc_probe,
        .remove = uml_rtc_remove,
        .driver = {
                .name = "uml-rtc",
        },
};

static int __init uml_rtc_init(void)
{
        struct platform_device *pdev;
        int err;

        err = platform_driver_register(&uml_rtc_driver);
        if (err)
                return err;

        pdev = platform_device_alloc("uml-rtc", 0);
        if (!pdev) {
                err = -ENOMEM;
                goto unregister;
        }

        err = platform_device_add(pdev);
        if (err)
                goto unregister;
        return 0;

unregister:
        platform_device_put(pdev);
        platform_driver_unregister(&uml_rtc_driver);
        return err;
}
device_initcall(uml_rtc_init);