// SPDX-License-Identifier: GPL-2.0
/*
 * Real Time Clock driver for Freescale MC13XXX PMIC
 *
 * (C) 2009 Sascha Hauer, Pengutronix
 * (C) 2009 Uwe Kleine-Koenig, Pengutronix
 */

#include <linux/mfd/mc13xxx.h>
#include <linux/platform_device.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/slab.h>
#include <linux/rtc.h>

#define DRIVER_NAME "mc13xxx-rtc"

#define MC13XXX_RTCTOD  20
#define MC13XXX_RTCTODA 21
#define MC13XXX_RTCDAY  22
#define MC13XXX_RTCDAYA 23

#define SEC_PER_DAY     (24 * 60 * 60)

struct mc13xxx_rtc {
        struct rtc_device *rtc;
        struct mc13xxx *mc13xxx;
        int valid;
};

static int mc13xxx_rtc_irq_enable_unlocked(struct device *dev,
                unsigned int enabled, int irq)
{
        struct mc13xxx_rtc *priv = dev_get_drvdata(dev);
        int (*func)(struct mc13xxx *mc13xxx, int irq);

        if (!priv->valid)
                return -ENODATA;

        func = enabled ? mc13xxx_irq_unmask : mc13xxx_irq_mask;
        return func(priv->mc13xxx, irq);
}

static int mc13xxx_rtc_alarm_irq_enable(struct device *dev,
                                        unsigned int enabled)
{
        struct mc13xxx_rtc *priv = dev_get_drvdata(dev);
        int ret;

        mc13xxx_lock(priv->mc13xxx);

        ret = mc13xxx_rtc_irq_enable_unlocked(dev, enabled, MC13XXX_IRQ_TODA);

        mc13xxx_unlock(priv->mc13xxx);

        return ret;
}

static int mc13xxx_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        struct mc13xxx_rtc *priv = dev_get_drvdata(dev);
        unsigned int seconds, days1, days2;

        if (!priv->valid)
                return -ENODATA;

        do {
                int ret;

                ret = mc13xxx_reg_read(priv->mc13xxx, MC13XXX_RTCDAY, &days1);
                if (ret)
                        return ret;

                ret = mc13xxx_reg_read(priv->mc13xxx, MC13XXX_RTCTOD, &seconds);
                if (ret)
                        return ret;

                ret = mc13xxx_reg_read(priv->mc13xxx, MC13XXX_RTCDAY, &days2);
                if (ret)
                        return ret;
        } while (days1 != days2);

        rtc_time64_to_tm((time64_t)days1 * SEC_PER_DAY + seconds, tm);

        return 0;
}

static int mc13xxx_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        struct mc13xxx_rtc *priv = dev_get_drvdata(dev);
        unsigned int seconds, days;
        unsigned int alarmseconds;
        int ret;

        days = div_s64_rem(rtc_tm_to_time64(tm), SEC_PER_DAY, &seconds);

        mc13xxx_lock(priv->mc13xxx);

        /*
         * temporarily invalidate alarm to prevent triggering it when the day is
         * already updated while the time isn't yet.
         */
        ret = mc13xxx_reg_read(priv->mc13xxx, MC13XXX_RTCTODA, &alarmseconds);
        if (unlikely(ret))
                goto out;

        if (alarmseconds < SEC_PER_DAY) {
                ret = mc13xxx_reg_write(priv->mc13xxx,
                                MC13XXX_RTCTODA, 0x1ffff);
                if (unlikely(ret))
                        goto out;
        }

        /*
         * write seconds=0 to prevent a day switch between writing days
         * and seconds below
         */
        ret = mc13xxx_reg_write(priv->mc13xxx, MC13XXX_RTCTOD, 0);
        if (unlikely(ret))
                goto out;

        ret = mc13xxx_reg_write(priv->mc13xxx, MC13XXX_RTCDAY, days);
        if (unlikely(ret))
                goto out;

        ret = mc13xxx_reg_write(priv->mc13xxx, MC13XXX_RTCTOD, seconds);
        if (unlikely(ret))
                goto out;

        /* restore alarm */
        if (alarmseconds < SEC_PER_DAY) {
                ret = mc13xxx_reg_write(priv->mc13xxx,
                                MC13XXX_RTCTODA, alarmseconds);
                if (unlikely(ret))
                        goto out;
        }

        if (!priv->valid) {
                ret = mc13xxx_irq_unmask(priv->mc13xxx, MC13XXX_IRQ_RTCRST);
        }

out:
        priv->valid = !ret;

        mc13xxx_unlock(priv->mc13xxx);

        return ret;
}

static int mc13xxx_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
        struct mc13xxx_rtc *priv = dev_get_drvdata(dev);
        unsigned int seconds, days;
        time64_t s1970;
        int enabled, pending;
        int ret;

        mc13xxx_lock(priv->mc13xxx);

        ret = mc13xxx_reg_read(priv->mc13xxx, MC13XXX_RTCTODA, &seconds);
        if (unlikely(ret))
                goto out;
        if (seconds >= SEC_PER_DAY) {
                ret = -ENODATA;
                goto out;
        }

        ret = mc13xxx_reg_read(priv->mc13xxx, MC13XXX_RTCDAY, &days);
        if (unlikely(ret))
                goto out;

        ret = mc13xxx_irq_status(priv->mc13xxx, MC13XXX_IRQ_TODA,
                        &enabled, &pending);

out:
        mc13xxx_unlock(priv->mc13xxx);

        if (ret)
                return ret;

        alarm->enabled = enabled;
        alarm->pending = pending;

        s1970 = (time64_t)days * SEC_PER_DAY + seconds;

        rtc_time64_to_tm(s1970, &alarm->time);
        dev_dbg(dev, "%s: %lld\n", __func__, (long long)s1970);

        return 0;
}

static int mc13xxx_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
        struct mc13xxx_rtc *priv = dev_get_drvdata(dev);
        time64_t s1970;
        u32 seconds, days;
        int ret;

        mc13xxx_lock(priv->mc13xxx);

        /* disable alarm to prevent false triggering */
        ret = mc13xxx_reg_write(priv->mc13xxx, MC13XXX_RTCTODA, 0x1ffff);
        if (unlikely(ret))
                goto out;

        s1970 = rtc_tm_to_time64(&alarm->time);

        dev_dbg(dev, "%s: %s %lld\n", __func__, alarm->enabled ? "on" : "off",
                        (long long)s1970);

        ret = mc13xxx_rtc_irq_enable_unlocked(dev, alarm->enabled,
                        MC13XXX_IRQ_TODA);
        if (unlikely(ret))
                goto out;

        days = div_s64_rem(s1970, SEC_PER_DAY, &seconds);

        ret = mc13xxx_reg_write(priv->mc13xxx, MC13XXX_RTCDAYA, days);
        if (unlikely(ret))
                goto out;

        ret = mc13xxx_reg_write(priv->mc13xxx, MC13XXX_RTCTODA, seconds);

out:
        mc13xxx_unlock(priv->mc13xxx);

        return ret;
}

static irqreturn_t mc13xxx_rtc_alarm_handler(int irq, void *dev)
{
        struct mc13xxx_rtc *priv = dev;

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

        return IRQ_HANDLED;
}

static const struct rtc_class_ops mc13xxx_rtc_ops = {
        .read_time = mc13xxx_rtc_read_time,
        .set_time = mc13xxx_rtc_set_time,
        .read_alarm = mc13xxx_rtc_read_alarm,
        .set_alarm = mc13xxx_rtc_set_alarm,
        .alarm_irq_enable = mc13xxx_rtc_alarm_irq_enable,
};

static irqreturn_t mc13xxx_rtc_reset_handler(int irq, void *dev)
{
        struct mc13xxx_rtc *priv = dev;
        struct mc13xxx *mc13xxx = priv->mc13xxx;

        priv->valid = 0;

        mc13xxx_irq_mask(mc13xxx, irq);

        return IRQ_HANDLED;
}

static int __init mc13xxx_rtc_probe(struct platform_device *pdev)
{
        int ret;
        struct mc13xxx_rtc *priv;
        struct mc13xxx *mc13xxx;

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

        mc13xxx = dev_get_drvdata(pdev->dev.parent);
        priv->mc13xxx = mc13xxx;
        priv->valid = 1;

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

        priv->rtc->ops = &mc13xxx_rtc_ops;
        /* 15bit days + hours, minutes, seconds */
        priv->rtc->range_max = (timeu64_t)(1 << 15) * SEC_PER_DAY - 1;

        mc13xxx_lock(mc13xxx);

        ret = mc13xxx_irq_request(mc13xxx, MC13XXX_IRQ_RTCRST,
                        mc13xxx_rtc_reset_handler, DRIVER_NAME, priv);
        if (ret)
                goto err_irq_request;

        ret = mc13xxx_irq_request_nounmask(mc13xxx, MC13XXX_IRQ_TODA,
                        mc13xxx_rtc_alarm_handler, DRIVER_NAME, priv);
        if (ret)
                goto err_irq_request;

        mc13xxx_unlock(mc13xxx);

        ret = devm_rtc_register_device(priv->rtc);
        if (ret) {
                mc13xxx_lock(mc13xxx);
                goto err_irq_request;
        }

        return 0;

err_irq_request:
        mc13xxx_irq_free(mc13xxx, MC13XXX_IRQ_TODA, priv);
        mc13xxx_irq_free(mc13xxx, MC13XXX_IRQ_RTCRST, priv);

        mc13xxx_unlock(mc13xxx);

        return ret;
}

static void mc13xxx_rtc_remove(struct platform_device *pdev)
{
        struct mc13xxx_rtc *priv = platform_get_drvdata(pdev);

        mc13xxx_lock(priv->mc13xxx);

        mc13xxx_irq_free(priv->mc13xxx, MC13XXX_IRQ_TODA, priv);
        mc13xxx_irq_free(priv->mc13xxx, MC13XXX_IRQ_RTCRST, priv);

        mc13xxx_unlock(priv->mc13xxx);
}

static const struct platform_device_id mc13xxx_rtc_idtable[] = {
        {
                .name = "mc13783-rtc",
        }, {
                .name = "mc13892-rtc",
        }, {
                .name = "mc34708-rtc",
        },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(platform, mc13xxx_rtc_idtable);

static struct platform_driver mc13xxx_rtc_driver = {
        .id_table = mc13xxx_rtc_idtable,
        .remove = mc13xxx_rtc_remove,
        .driver = {
                .name = DRIVER_NAME,
        },
};

module_platform_driver_probe(mc13xxx_rtc_driver, &mc13xxx_rtc_probe);

MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");
MODULE_DESCRIPTION("RTC driver for Freescale MC13XXX PMIC");
MODULE_LICENSE("GPL v2");