// SPDX-License-Identifier: GPL-2.0
/*
 * Driver for the RTC in Marvell SoCs.
 */

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/rtc.h>
#include <linux/bcd.h>
#include <linux/bitops.h>
#include <linux/io.h>
#include <linux/platform_device.h>
#include <linux/of.h>
#include <linux/delay.h>
#include <linux/clk.h>
#include <linux/gfp.h>
#include <linux/module.h>


#define RTC_TIME_REG_OFFS       0
#define RTC_SECONDS_OFFS        0
#define RTC_MINUTES_OFFS        8
#define RTC_HOURS_OFFS          16
#define RTC_WDAY_OFFS           24
#define RTC_HOURS_12H_MODE      BIT(22) /* 12 hour mode */

#define RTC_DATE_REG_OFFS       4
#define RTC_MDAY_OFFS           0
#define RTC_MONTH_OFFS          8
#define RTC_YEAR_OFFS           16

#define RTC_ALARM_TIME_REG_OFFS 8
#define RTC_ALARM_DATE_REG_OFFS 0xc
#define RTC_ALARM_VALID         BIT(7)

#define RTC_ALARM_INTERRUPT_MASK_REG_OFFS       0x10
#define RTC_ALARM_INTERRUPT_CASUE_REG_OFFS      0x14

struct rtc_plat_data {
        struct rtc_device *rtc;
        void __iomem *ioaddr;
        int             irq;
        struct clk      *clk;
};

static int mv_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        struct rtc_plat_data *pdata = dev_get_drvdata(dev);
        void __iomem *ioaddr = pdata->ioaddr;
        u32     rtc_reg;

        rtc_reg = (bin2bcd(tm->tm_sec) << RTC_SECONDS_OFFS) |
                (bin2bcd(tm->tm_min) << RTC_MINUTES_OFFS) |
                (bin2bcd(tm->tm_hour) << RTC_HOURS_OFFS) |
                (bin2bcd(tm->tm_wday) << RTC_WDAY_OFFS);
        writel(rtc_reg, ioaddr + RTC_TIME_REG_OFFS);

        rtc_reg = (bin2bcd(tm->tm_mday) << RTC_MDAY_OFFS) |
                (bin2bcd(tm->tm_mon + 1) << RTC_MONTH_OFFS) |
                (bin2bcd(tm->tm_year - 100) << RTC_YEAR_OFFS);
        writel(rtc_reg, ioaddr + RTC_DATE_REG_OFFS);

        return 0;
}

static int mv_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        struct rtc_plat_data *pdata = dev_get_drvdata(dev);
        void __iomem *ioaddr = pdata->ioaddr;
        u32     rtc_time, rtc_date;
        unsigned int year, month, day, hour, minute, second, wday;

        rtc_time = readl(ioaddr + RTC_TIME_REG_OFFS);
        rtc_date = readl(ioaddr + RTC_DATE_REG_OFFS);

        second = rtc_time & 0x7f;
        minute = (rtc_time >> RTC_MINUTES_OFFS) & 0x7f;
        hour = (rtc_time >> RTC_HOURS_OFFS) & 0x3f; /* assume 24 hour mode */
        wday = (rtc_time >> RTC_WDAY_OFFS) & 0x7;

        day = rtc_date & 0x3f;
        month = (rtc_date >> RTC_MONTH_OFFS) & 0x3f;
        year = (rtc_date >> RTC_YEAR_OFFS) & 0xff;

        tm->tm_sec = bcd2bin(second);
        tm->tm_min = bcd2bin(minute);
        tm->tm_hour = bcd2bin(hour);
        tm->tm_mday = bcd2bin(day);
        tm->tm_wday = bcd2bin(wday);
        tm->tm_mon = bcd2bin(month) - 1;
        /* hw counts from year 2000, but tm_year is relative to 1900 */
        tm->tm_year = bcd2bin(year) + 100;

        return 0;
}

static int mv_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
        struct rtc_plat_data *pdata = dev_get_drvdata(dev);
        void __iomem *ioaddr = pdata->ioaddr;
        u32     rtc_time, rtc_date;
        unsigned int year, month, day, hour, minute, second, wday;

        rtc_time = readl(ioaddr + RTC_ALARM_TIME_REG_OFFS);
        rtc_date = readl(ioaddr + RTC_ALARM_DATE_REG_OFFS);

        second = rtc_time & 0x7f;
        minute = (rtc_time >> RTC_MINUTES_OFFS) & 0x7f;
        hour = (rtc_time >> RTC_HOURS_OFFS) & 0x3f; /* assume 24 hour mode */
        wday = (rtc_time >> RTC_WDAY_OFFS) & 0x7;

        day = rtc_date & 0x3f;
        month = (rtc_date >> RTC_MONTH_OFFS) & 0x3f;
        year = (rtc_date >> RTC_YEAR_OFFS) & 0xff;

        alm->time.tm_sec = bcd2bin(second);
        alm->time.tm_min = bcd2bin(minute);
        alm->time.tm_hour = bcd2bin(hour);
        alm->time.tm_mday = bcd2bin(day);
        alm->time.tm_wday = bcd2bin(wday);
        alm->time.tm_mon = bcd2bin(month) - 1;
        /* hw counts from year 2000, but tm_year is relative to 1900 */
        alm->time.tm_year = bcd2bin(year) + 100;

        alm->enabled = !!readl(ioaddr + RTC_ALARM_INTERRUPT_MASK_REG_OFFS);

        return rtc_valid_tm(&alm->time);
}

static int mv_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
        struct rtc_plat_data *pdata = dev_get_drvdata(dev);
        void __iomem *ioaddr = pdata->ioaddr;
        u32 rtc_reg = 0;

        if (alm->time.tm_sec >= 0)
                rtc_reg |= (RTC_ALARM_VALID | bin2bcd(alm->time.tm_sec))
                        << RTC_SECONDS_OFFS;
        if (alm->time.tm_min >= 0)
                rtc_reg |= (RTC_ALARM_VALID | bin2bcd(alm->time.tm_min))
                        << RTC_MINUTES_OFFS;
        if (alm->time.tm_hour >= 0)
                rtc_reg |= (RTC_ALARM_VALID | bin2bcd(alm->time.tm_hour))
                        << RTC_HOURS_OFFS;

        writel(rtc_reg, ioaddr + RTC_ALARM_TIME_REG_OFFS);

        if (alm->time.tm_mday >= 0)
                rtc_reg = (RTC_ALARM_VALID | bin2bcd(alm->time.tm_mday))
                        << RTC_MDAY_OFFS;
        else
                rtc_reg = 0;

        if (alm->time.tm_mon >= 0)
                rtc_reg |= (RTC_ALARM_VALID | bin2bcd(alm->time.tm_mon + 1))
                        << RTC_MONTH_OFFS;

        if (alm->time.tm_year >= 0)
                rtc_reg |= (RTC_ALARM_VALID | bin2bcd(alm->time.tm_year - 100))
                        << RTC_YEAR_OFFS;

        writel(rtc_reg, ioaddr + RTC_ALARM_DATE_REG_OFFS);
        writel(0, ioaddr + RTC_ALARM_INTERRUPT_CASUE_REG_OFFS);
        writel(alm->enabled ? 1 : 0,
               ioaddr + RTC_ALARM_INTERRUPT_MASK_REG_OFFS);

        return 0;
}

static int mv_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
        struct rtc_plat_data *pdata = dev_get_drvdata(dev);
        void __iomem *ioaddr = pdata->ioaddr;

        if (pdata->irq < 0)
                return -EINVAL; /* fall back into rtc-dev's emulation */

        if (enabled)
                writel(1, ioaddr + RTC_ALARM_INTERRUPT_MASK_REG_OFFS);
        else
                writel(0, ioaddr + RTC_ALARM_INTERRUPT_MASK_REG_OFFS);
        return 0;
}

static irqreturn_t mv_rtc_interrupt(int irq, void *data)
{
        struct rtc_plat_data *pdata = data;
        void __iomem *ioaddr = pdata->ioaddr;

        /* alarm irq? */
        if (!readl(ioaddr + RTC_ALARM_INTERRUPT_CASUE_REG_OFFS))
                return IRQ_NONE;

        /* clear interrupt */
        writel(0, ioaddr + RTC_ALARM_INTERRUPT_CASUE_REG_OFFS);
        rtc_update_irq(pdata->rtc, 1, RTC_IRQF | RTC_AF);
        return IRQ_HANDLED;
}

static const struct rtc_class_ops mv_rtc_ops = {
        .read_time      = mv_rtc_read_time,
        .set_time       = mv_rtc_set_time,
        .read_alarm     = mv_rtc_read_alarm,
        .set_alarm      = mv_rtc_set_alarm,
        .alarm_irq_enable = mv_rtc_alarm_irq_enable,
};

static int __init mv_rtc_probe(struct platform_device *pdev)
{
        struct rtc_plat_data *pdata;
        u32 rtc_time;
        int ret = 0;

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

        pdata->ioaddr = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(pdata->ioaddr))
                return PTR_ERR(pdata->ioaddr);

        pdata->clk = devm_clk_get(&pdev->dev, NULL);
        /* Not all SoCs require a clock.*/
        if (!IS_ERR(pdata->clk))
                clk_prepare_enable(pdata->clk);

        /* make sure the 24 hour mode is enabled */
        rtc_time = readl(pdata->ioaddr + RTC_TIME_REG_OFFS);
        if (rtc_time & RTC_HOURS_12H_MODE) {
                dev_err(&pdev->dev, "12 Hour mode is enabled but not supported.\n");
                ret = -EINVAL;
                goto out;
        }

        /* make sure it is actually functional */
        if (rtc_time == 0x01000000) {
                ssleep(1);
                rtc_time = readl(pdata->ioaddr + RTC_TIME_REG_OFFS);
                if (rtc_time == 0x01000000) {
                        dev_err(&pdev->dev, "internal RTC not ticking\n");
                        ret = -ENODEV;
                        goto out;
                }
        }

        pdata->irq = platform_get_irq(pdev, 0);

        platform_set_drvdata(pdev, pdata);

        pdata->rtc = devm_rtc_allocate_device(&pdev->dev);
        if (IS_ERR(pdata->rtc)) {
                ret = PTR_ERR(pdata->rtc);
                goto out;
        }

        if (pdata->irq >= 0) {
                writel(0, pdata->ioaddr + RTC_ALARM_INTERRUPT_MASK_REG_OFFS);
                if (devm_request_irq(&pdev->dev, pdata->irq, mv_rtc_interrupt,
                                     IRQF_SHARED,
                                     pdev->name, pdata) < 0) {
                        dev_warn(&pdev->dev, "interrupt not available.\n");
                        pdata->irq = -1;
                }
        }

        if (pdata->irq >= 0)
                device_init_wakeup(&pdev->dev, true);
        else
                clear_bit(RTC_FEATURE_ALARM, pdata->rtc->features);

        pdata->rtc->ops = &mv_rtc_ops;
        pdata->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
        pdata->rtc->range_max = RTC_TIMESTAMP_END_2099;

        ret = devm_rtc_register_device(pdata->rtc);
        if (!ret)
                return 0;
out:
        if (!IS_ERR(pdata->clk))
                clk_disable_unprepare(pdata->clk);

        return ret;
}

static void __exit mv_rtc_remove(struct platform_device *pdev)
{
        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

        if (pdata->irq >= 0)
                device_init_wakeup(&pdev->dev, false);

        if (!IS_ERR(pdata->clk))
                clk_disable_unprepare(pdata->clk);
}

#ifdef CONFIG_OF
static const struct of_device_id rtc_mv_of_match_table[] = {
        { .compatible = "marvell,orion-rtc", },
        {}
};
MODULE_DEVICE_TABLE(of, rtc_mv_of_match_table);
#endif

/*
 * mv_rtc_remove() lives in .exit.text. For drivers registered via
 * module_platform_driver_probe() this is ok because they cannot get unbound at
 * runtime. So mark the driver struct with __refdata to prevent modpost
 * triggering a section mismatch warning.
 */
static struct platform_driver mv_rtc_driver __refdata = {
        .remove         = __exit_p(mv_rtc_remove),
        .driver         = {
                .name   = "rtc-mv",
                .of_match_table = of_match_ptr(rtc_mv_of_match_table),
        },
};

module_platform_driver_probe(mv_rtc_driver, mv_rtc_probe);

MODULE_AUTHOR("Saeed Bishara <saeed@marvell.com>");
MODULE_DESCRIPTION("Marvell RTC driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:rtc-mv");