// 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;

	del_timer(&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
		del_timer(&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 = from_timer(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, 1);
	}

	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);