// SPDX-License-Identifier: GPL-2.0
/*
 * An RTC test device/driver
 * Copyright (C) 2005 Tower Technologies
 * Author: Alessandro Zummo <a.zummo@towertech.it>
 */

#include <linux/module.h>
#include <linux/err.h>
#include <linux/rtc.h>
#include <linux/platform_device.h>

#define MAX_RTC_TEST 3

struct rtc_test_data {
        struct rtc_device *rtc;
        time64_t offset;
        struct timer_list alarm;
        bool alarm_en;
};

static struct platform_device *pdev[MAX_RTC_TEST];

static int test_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        struct rtc_test_data *rtd = dev_get_drvdata(dev);
        time64_t alarm;

        alarm = (rtd->alarm.expires - jiffies) / HZ;
        alarm += ktime_get_real_seconds() + rtd->offset;

        rtc_time64_to_tm(alarm, &alrm->time);
        alrm->enabled = rtd->alarm_en;

        return 0;
}

static int test_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        struct rtc_test_data *rtd = dev_get_drvdata(dev);
        ktime_t timeout;
        u64 expires;

        timeout = rtc_tm_to_time64(&alrm->time) - ktime_get_real_seconds();
        timeout -= rtd->offset;

        timer_delete(&rtd->alarm);

        expires = jiffies + timeout * HZ;
        if (expires > U32_MAX)
                expires = U32_MAX;

        rtd->alarm.expires = expires;

        if (alrm->enabled)
                add_timer(&rtd->alarm);

        rtd->alarm_en = alrm->enabled;

        return 0;
}

static int test_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        struct rtc_test_data *rtd = dev_get_drvdata(dev);

        rtc_time64_to_tm(ktime_get_real_seconds() + rtd->offset, tm);

        return 0;
}

static int test_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        struct rtc_test_data *rtd = dev_get_drvdata(dev);

        rtd->offset = rtc_tm_to_time64(tm) - ktime_get_real_seconds();

        return 0;
}

static int test_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
{
        struct rtc_test_data *rtd = dev_get_drvdata(dev);

        rtd->alarm_en = enable;
        if (enable)
                add_timer(&rtd->alarm);
        else
                timer_delete(&rtd->alarm);

        return 0;
}

static const struct rtc_class_ops test_rtc_ops_noalm = {
        .read_time = test_rtc_read_time,
        .set_time = test_rtc_set_time,
        .alarm_irq_enable = test_rtc_alarm_irq_enable,
};

static const struct rtc_class_ops test_rtc_ops = {
        .read_time = test_rtc_read_time,
        .set_time = test_rtc_set_time,
        .read_alarm = test_rtc_read_alarm,
        .set_alarm = test_rtc_set_alarm,
        .alarm_irq_enable = test_rtc_alarm_irq_enable,
};

static void test_rtc_alarm_handler(struct timer_list *t)
{
        struct rtc_test_data *rtd = timer_container_of(rtd, t, alarm);

        rtc_update_irq(rtd->rtc, 1, RTC_AF | RTC_IRQF);
}

static int test_probe(struct platform_device *plat_dev)
{
        struct rtc_test_data *rtd;

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

        platform_set_drvdata(plat_dev, rtd);

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

        switch (plat_dev->id) {
        case 0:
                rtd->rtc->ops = &test_rtc_ops_noalm;
                break;
        default:
                rtd->rtc->ops = &test_rtc_ops;
                device_init_wakeup(&plat_dev->dev, true);
        }

        timer_setup(&rtd->alarm, test_rtc_alarm_handler, 0);
        rtd->alarm.expires = 0;

        return devm_rtc_register_device(rtd->rtc);
}

static struct platform_driver test_driver = {
        .probe  = test_probe,
        .driver = {
                .name = "rtc-test",
        },
};

static int __init test_init(void)
{
        int i, err;

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

        err = -ENOMEM;
        for (i = 0; i < MAX_RTC_TEST; i++) {
                pdev[i] = platform_device_alloc("rtc-test", i);
                if (!pdev[i])
                        goto exit_free_mem;
        }

        for (i = 0; i < MAX_RTC_TEST; i++) {
                err = platform_device_add(pdev[i]);
                if (err)
                        goto exit_device_del;
        }

        return 0;

exit_device_del:
        for (; i > 0; i--)
                platform_device_del(pdev[i - 1]);

exit_free_mem:
        for (i = 0; i < MAX_RTC_TEST; i++)
                platform_device_put(pdev[i]);

        platform_driver_unregister(&test_driver);
        return err;
}

static void __exit test_exit(void)
{
        int i;

        for (i = 0; i < MAX_RTC_TEST; i++)
                platform_device_unregister(pdev[i]);

        platform_driver_unregister(&test_driver);
}

MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
MODULE_DESCRIPTION("RTC test driver/device");
MODULE_LICENSE("GPL v2");

module_init(test_init);
module_exit(test_exit);