// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2019 BayLibre, SAS
 * Author: Neil Armstrong <narmstrong@baylibre.com>
 * Copyright (C) 2015 Amlogic, Inc. All rights reserved.
 */
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/time64.h>

struct meson_vrtc_data {
        void __iomem *io_alarm;
        unsigned long alarm_time;
        bool enabled;
};

static int meson_vrtc_read_time(struct device *dev, struct rtc_time *tm)
{
        struct timespec64 time;

        dev_dbg(dev, "%s\n", __func__);
        ktime_get_real_ts64(&time);
        rtc_time64_to_tm(time.tv_sec, tm);

        return 0;
}

static void meson_vrtc_set_wakeup_time(struct meson_vrtc_data *vrtc,
                                       unsigned long time)
{
        writel_relaxed(time, vrtc->io_alarm);
}

static int meson_vrtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
        struct meson_vrtc_data *vrtc = dev_get_drvdata(dev);

        dev_dbg(dev, "%s: alarm->enabled=%d\n", __func__, alarm->enabled);
        if (alarm->enabled)
                vrtc->alarm_time = rtc_tm_to_time64(&alarm->time);
        else
                vrtc->alarm_time = 0;

        return 0;
}

static int meson_vrtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
        struct meson_vrtc_data *vrtc = dev_get_drvdata(dev);

        vrtc->enabled = enabled;
        return 0;
}

static const struct rtc_class_ops meson_vrtc_ops = {
        .read_time = meson_vrtc_read_time,
        .set_alarm = meson_vrtc_set_alarm,
        .alarm_irq_enable = meson_vrtc_alarm_irq_enable,
};

static int meson_vrtc_probe(struct platform_device *pdev)
{
        struct meson_vrtc_data *vrtc;
        struct rtc_device *rtc;

        vrtc = devm_kzalloc(&pdev->dev, sizeof(*vrtc), GFP_KERNEL);
        if (!vrtc)
                return -ENOMEM;

        vrtc->io_alarm = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(vrtc->io_alarm))
                return PTR_ERR(vrtc->io_alarm);

        device_init_wakeup(&pdev->dev, true);

        platform_set_drvdata(pdev, vrtc);

        rtc = devm_rtc_allocate_device(&pdev->dev);
        if (IS_ERR(rtc))
                return PTR_ERR(rtc);

        rtc->ops = &meson_vrtc_ops;
        return devm_rtc_register_device(rtc);
}

static int __maybe_unused meson_vrtc_suspend(struct device *dev)
{
        struct meson_vrtc_data *vrtc = dev_get_drvdata(dev);

        dev_dbg(dev, "%s\n", __func__);
        if (vrtc->alarm_time) {
                unsigned long local_time;
                long alarm_secs;
                struct timespec64 time;

                ktime_get_real_ts64(&time);
                local_time = time.tv_sec;

                dev_dbg(dev, "alarm_time = %lus, local_time=%lus\n",
                        vrtc->alarm_time, local_time);
                alarm_secs = vrtc->alarm_time - local_time;
                if (alarm_secs > 0) {
                        meson_vrtc_set_wakeup_time(vrtc, alarm_secs);
                        dev_dbg(dev, "system will wakeup in %lds.\n",
                                alarm_secs);
                } else {
                        dev_err(dev, "alarm time already passed: %lds.\n",
                                alarm_secs);
                }
        }

        return 0;
}

static int __maybe_unused meson_vrtc_resume(struct device *dev)
{
        struct meson_vrtc_data *vrtc = dev_get_drvdata(dev);

        dev_dbg(dev, "%s\n", __func__);

        vrtc->alarm_time = 0;
        meson_vrtc_set_wakeup_time(vrtc, 0);
        return 0;
}

static SIMPLE_DEV_PM_OPS(meson_vrtc_pm_ops,
                         meson_vrtc_suspend, meson_vrtc_resume);

static const struct of_device_id meson_vrtc_dt_match[] = {
        { .compatible = "amlogic,meson-vrtc"},
        {},
};
MODULE_DEVICE_TABLE(of, meson_vrtc_dt_match);

static struct platform_driver meson_vrtc_driver = {
        .probe = meson_vrtc_probe,
        .driver = {
                .name = "meson-vrtc",
                .of_match_table = meson_vrtc_dt_match,
                .pm = &meson_vrtc_pm_ops,
        },
};

module_platform_driver(meson_vrtc_driver);

MODULE_DESCRIPTION("Amlogic Virtual Wakeup RTC Timer driver");
MODULE_LICENSE("GPL");