// SPDX-License-Identifier: GPL-2.0-only
/*
 * drivers/rtc/rtc-vt8500.c
 *
 *  Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
 *
 * Based on rtc-pxa.c
 */

#include <linux/module.h>
#include <linux/rtc.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/bcd.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/of.h>

/*
 * Register definitions
 */
#define VT8500_RTC_TS           0x00    /* Time set */
#define VT8500_RTC_DS           0x04    /* Date set */
#define VT8500_RTC_AS           0x08    /* Alarm set */
#define VT8500_RTC_CR           0x0c    /* Control */
#define VT8500_RTC_TR           0x10    /* Time read */
#define VT8500_RTC_DR           0x14    /* Date read */
#define VT8500_RTC_WS           0x18    /* Write status */
#define VT8500_RTC_CL           0x20    /* Calibration */
#define VT8500_RTC_IS           0x24    /* Interrupt status */
#define VT8500_RTC_ST           0x28    /* Status */

#define INVALID_TIME_BIT        (1 << 31)

#define DATE_CENTURY_S          19
#define DATE_YEAR_S             11
#define DATE_YEAR_MASK          (0xff << DATE_YEAR_S)
#define DATE_MONTH_S            6
#define DATE_MONTH_MASK         (0x1f << DATE_MONTH_S)
#define DATE_DAY_MASK           0x3f

#define TIME_DOW_S              20
#define TIME_DOW_MASK           (0x07 << TIME_DOW_S)
#define TIME_HOUR_S             14
#define TIME_HOUR_MASK          (0x3f << TIME_HOUR_S)
#define TIME_MIN_S              7
#define TIME_MIN_MASK           (0x7f << TIME_MIN_S)
#define TIME_SEC_MASK           0x7f

#define ALARM_DAY_S             20
#define ALARM_DAY_MASK          (0x3f << ALARM_DAY_S)

#define ALARM_DAY_BIT           (1 << 29)
#define ALARM_HOUR_BIT          (1 << 28)
#define ALARM_MIN_BIT           (1 << 27)
#define ALARM_SEC_BIT           (1 << 26)

#define ALARM_ENABLE_MASK       (ALARM_DAY_BIT \
                                | ALARM_HOUR_BIT \
                                | ALARM_MIN_BIT \
                                | ALARM_SEC_BIT)

#define VT8500_RTC_CR_ENABLE    (1 << 0)        /* Enable RTC */
#define VT8500_RTC_CR_12H       (1 << 1)        /* 12h time format */
#define VT8500_RTC_CR_SM_ENABLE (1 << 2)        /* Enable periodic irqs */
#define VT8500_RTC_CR_SM_SEC    (1 << 3)        /* 0: 1Hz/60, 1: 1Hz */
#define VT8500_RTC_CR_CALIB     (1 << 4)        /* Enable calibration */

#define VT8500_RTC_IS_ALARM     (1 << 0)        /* Alarm interrupt status */

struct vt8500_rtc {
        void __iomem            *regbase;
        int                     irq_alarm;
        struct rtc_device       *rtc;
        spinlock_t              lock;           /* Protects this structure */
};

static irqreturn_t vt8500_rtc_irq(int irq, void *dev_id)
{
        struct vt8500_rtc *vt8500_rtc = dev_id;
        u32 isr;
        unsigned long events = 0;

        spin_lock(&vt8500_rtc->lock);

        /* clear interrupt sources */
        isr = readl(vt8500_rtc->regbase + VT8500_RTC_IS);
        writel(isr, vt8500_rtc->regbase + VT8500_RTC_IS);

        spin_unlock(&vt8500_rtc->lock);

        if (isr & VT8500_RTC_IS_ALARM)
                events |= RTC_AF | RTC_IRQF;

        rtc_update_irq(vt8500_rtc->rtc, 1, events);

        return IRQ_HANDLED;
}

static int vt8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
        u32 date, time;

        date = readl(vt8500_rtc->regbase + VT8500_RTC_DR);
        time = readl(vt8500_rtc->regbase + VT8500_RTC_TR);

        tm->tm_sec = bcd2bin(time & TIME_SEC_MASK);
        tm->tm_min = bcd2bin((time & TIME_MIN_MASK) >> TIME_MIN_S);
        tm->tm_hour = bcd2bin((time & TIME_HOUR_MASK) >> TIME_HOUR_S);
        tm->tm_mday = bcd2bin(date & DATE_DAY_MASK);
        tm->tm_mon = bcd2bin((date & DATE_MONTH_MASK) >> DATE_MONTH_S) - 1;
        tm->tm_year = bcd2bin((date & DATE_YEAR_MASK) >> DATE_YEAR_S)
                        + ((date >> DATE_CENTURY_S) & 1 ? 200 : 100);
        tm->tm_wday = (time & TIME_DOW_MASK) >> TIME_DOW_S;

        return 0;
}

static int vt8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);

        writel((bin2bcd(tm->tm_year % 100) << DATE_YEAR_S)
                | (bin2bcd(tm->tm_mon + 1) << DATE_MONTH_S)
                | (bin2bcd(tm->tm_mday))
                | ((tm->tm_year >= 200) << DATE_CENTURY_S),
                vt8500_rtc->regbase + VT8500_RTC_DS);
        writel((bin2bcd(tm->tm_wday) << TIME_DOW_S)
                | (bin2bcd(tm->tm_hour) << TIME_HOUR_S)
                | (bin2bcd(tm->tm_min) << TIME_MIN_S)
                | (bin2bcd(tm->tm_sec)),
                vt8500_rtc->regbase + VT8500_RTC_TS);

        return 0;
}

static int vt8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
        u32 isr, alarm;

        alarm = readl(vt8500_rtc->regbase + VT8500_RTC_AS);
        isr = readl(vt8500_rtc->regbase + VT8500_RTC_IS);

        alrm->time.tm_mday = bcd2bin((alarm & ALARM_DAY_MASK) >> ALARM_DAY_S);
        alrm->time.tm_hour = bcd2bin((alarm & TIME_HOUR_MASK) >> TIME_HOUR_S);
        alrm->time.tm_min = bcd2bin((alarm & TIME_MIN_MASK) >> TIME_MIN_S);
        alrm->time.tm_sec = bcd2bin((alarm & TIME_SEC_MASK));

        alrm->enabled = (alarm & ALARM_ENABLE_MASK) ? 1 : 0;
        alrm->pending = (isr & VT8500_RTC_IS_ALARM) ? 1 : 0;

        return rtc_valid_tm(&alrm->time);
}

static int vt8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);

        writel((alrm->enabled ? ALARM_ENABLE_MASK : 0)
                | (bin2bcd(alrm->time.tm_mday) << ALARM_DAY_S)
                | (bin2bcd(alrm->time.tm_hour) << TIME_HOUR_S)
                | (bin2bcd(alrm->time.tm_min) << TIME_MIN_S)
                | (bin2bcd(alrm->time.tm_sec)),
                vt8500_rtc->regbase + VT8500_RTC_AS);

        return 0;
}

static int vt8500_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
        struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
        unsigned long tmp = readl(vt8500_rtc->regbase + VT8500_RTC_AS);

        if (enabled)
                tmp |= ALARM_ENABLE_MASK;
        else
                tmp &= ~ALARM_ENABLE_MASK;

        writel(tmp, vt8500_rtc->regbase + VT8500_RTC_AS);
        return 0;
}

static const struct rtc_class_ops vt8500_rtc_ops = {
        .read_time = vt8500_rtc_read_time,
        .set_time = vt8500_rtc_set_time,
        .read_alarm = vt8500_rtc_read_alarm,
        .set_alarm = vt8500_rtc_set_alarm,
        .alarm_irq_enable = vt8500_alarm_irq_enable,
};

static int vt8500_rtc_probe(struct platform_device *pdev)
{
        struct vt8500_rtc *vt8500_rtc;
        int ret;

        vt8500_rtc = devm_kzalloc(&pdev->dev,
                           sizeof(struct vt8500_rtc), GFP_KERNEL);
        if (!vt8500_rtc)
                return -ENOMEM;

        spin_lock_init(&vt8500_rtc->lock);
        platform_set_drvdata(pdev, vt8500_rtc);

        vt8500_rtc->irq_alarm = platform_get_irq(pdev, 0);
        if (vt8500_rtc->irq_alarm < 0)
                return vt8500_rtc->irq_alarm;

        vt8500_rtc->regbase = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(vt8500_rtc->regbase))
                return PTR_ERR(vt8500_rtc->regbase);

        /* Enable RTC and set it to 24-hour mode */
        writel(VT8500_RTC_CR_ENABLE,
               vt8500_rtc->regbase + VT8500_RTC_CR);

        vt8500_rtc->rtc = devm_rtc_allocate_device(&pdev->dev);
        if (IS_ERR(vt8500_rtc->rtc))
                return PTR_ERR(vt8500_rtc->rtc);

        vt8500_rtc->rtc->ops = &vt8500_rtc_ops;
        vt8500_rtc->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
        vt8500_rtc->rtc->range_max = RTC_TIMESTAMP_END_2199;

        ret = devm_request_irq(&pdev->dev, vt8500_rtc->irq_alarm,
                                vt8500_rtc_irq, 0, "rtc alarm", vt8500_rtc);
        if (ret < 0) {
                dev_err(&pdev->dev, "can't get irq %i, err %d\n",
                        vt8500_rtc->irq_alarm, ret);
                return ret;
        }

        return devm_rtc_register_device(vt8500_rtc->rtc);
}

static void vt8500_rtc_remove(struct platform_device *pdev)
{
        struct vt8500_rtc *vt8500_rtc = platform_get_drvdata(pdev);

        /* Disable alarm matching */
        writel(0, vt8500_rtc->regbase + VT8500_RTC_IS);
}

static const struct of_device_id wmt_dt_ids[] = {
        { .compatible = "via,vt8500-rtc", },
        {}
};
MODULE_DEVICE_TABLE(of, wmt_dt_ids);

static struct platform_driver vt8500_rtc_driver = {
        .probe          = vt8500_rtc_probe,
        .remove         = vt8500_rtc_remove,
        .driver         = {
                .name   = "vt8500-rtc",
                .of_match_table = wmt_dt_ids,
        },
};

module_platform_driver(vt8500_rtc_driver);

MODULE_AUTHOR("Alexey Charkov <alchark@gmail.com>");
MODULE_DESCRIPTION("VIA VT8500 SoC Realtime Clock Driver (RTC)");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:vt8500-rtc");