// SPDX-License-Identifier: GPL-2.0-only
/*
 * drivers/rtc/rtc-spear.c
 *
 * Copyright (C) 2010 ST Microelectronics
 * Rajeev Kumar<rajeev-dlh.kumar@st.com>
 */

#include <linux/bcd.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/slab.h>
#include <linux/spinlock.h>

/* RTC registers */
#define TIME_REG                0x00
#define DATE_REG                0x04
#define ALARM_TIME_REG          0x08
#define ALARM_DATE_REG          0x0C
#define CTRL_REG                0x10
#define STATUS_REG              0x14

/* TIME_REG & ALARM_TIME_REG */
#define SECONDS_UNITS           (0xf<<0)        /* seconds units position */
#define SECONDS_TENS            (0x7<<4)        /* seconds tens position */
#define MINUTES_UNITS           (0xf<<8)        /* minutes units position */
#define MINUTES_TENS            (0x7<<12)       /* minutes tens position */
#define HOURS_UNITS             (0xf<<16)       /* hours units position */
#define HOURS_TENS              (0x3<<20)       /* hours tens position */

/* DATE_REG & ALARM_DATE_REG */
#define DAYS_UNITS              (0xf<<0)        /* days units position */
#define DAYS_TENS               (0x3<<4)        /* days tens position */
#define MONTHS_UNITS            (0xf<<8)        /* months units position */
#define MONTHS_TENS             (0x1<<12)       /* months tens position */
#define YEARS_UNITS             (0xf<<16)       /* years units position */
#define YEARS_TENS              (0xf<<20)       /* years tens position */
#define YEARS_HUNDREDS          (0xf<<24)       /* years hundereds position */
#define YEARS_MILLENIUMS        (0xf<<28)       /* years millenium position */

/* MASK SHIFT TIME_REG & ALARM_TIME_REG*/
#define SECOND_SHIFT            0x00            /* seconds units */
#define MINUTE_SHIFT            0x08            /* minutes units position */
#define HOUR_SHIFT              0x10            /* hours units position */
#define MDAY_SHIFT              0x00            /* Month day shift */
#define MONTH_SHIFT             0x08            /* Month shift */
#define YEAR_SHIFT              0x10            /* Year shift */

#define SECOND_MASK             0x7F
#define MIN_MASK                0x7F
#define HOUR_MASK               0x3F
#define DAY_MASK                0x3F
#define MONTH_MASK              0x7F
#define YEAR_MASK               0xFFFF

/* date reg equal to time reg, for debug only */
#define TIME_BYP                (1<<9)
#define INT_ENABLE              (1<<31)         /* interrupt enable */

/* STATUS_REG */
#define CLK_UNCONNECTED         (1<<0)
#define PEND_WR_TIME            (1<<2)
#define PEND_WR_DATE            (1<<3)
#define LOST_WR_TIME            (1<<4)
#define LOST_WR_DATE            (1<<5)
#define RTC_INT_MASK            (1<<31)
#define STATUS_BUSY             (PEND_WR_TIME | PEND_WR_DATE)
#define STATUS_FAIL             (LOST_WR_TIME | LOST_WR_DATE)

struct spear_rtc_config {
        struct rtc_device *rtc;
        struct clk *clk;
        spinlock_t lock;
        void __iomem *ioaddr;
        unsigned int irq_wake;
};

static inline void spear_rtc_clear_interrupt(struct spear_rtc_config *config)
{
        unsigned int val;
        unsigned long flags;

        spin_lock_irqsave(&config->lock, flags);
        val = readl(config->ioaddr + STATUS_REG);
        val |= RTC_INT_MASK;
        writel(val, config->ioaddr + STATUS_REG);
        spin_unlock_irqrestore(&config->lock, flags);
}

static inline void spear_rtc_enable_interrupt(struct spear_rtc_config *config)
{
        unsigned int val;

        val = readl(config->ioaddr + CTRL_REG);
        if (!(val & INT_ENABLE)) {
                spear_rtc_clear_interrupt(config);
                val |= INT_ENABLE;
                writel(val, config->ioaddr + CTRL_REG);
        }
}

static inline void spear_rtc_disable_interrupt(struct spear_rtc_config *config)
{
        unsigned int val;

        val = readl(config->ioaddr + CTRL_REG);
        if (val & INT_ENABLE) {
                val &= ~INT_ENABLE;
                writel(val, config->ioaddr + CTRL_REG);
        }
}

static inline int is_write_complete(struct spear_rtc_config *config)
{
        int ret = 0;
        unsigned long flags;

        spin_lock_irqsave(&config->lock, flags);
        if ((readl(config->ioaddr + STATUS_REG)) & STATUS_FAIL)
                ret = -EIO;
        spin_unlock_irqrestore(&config->lock, flags);

        return ret;
}

static void rtc_wait_not_busy(struct spear_rtc_config *config)
{
        int status, count = 0;
        unsigned long flags;

        /* Assuming BUSY may stay active for 80 msec) */
        for (count = 0; count < 80; count++) {
                spin_lock_irqsave(&config->lock, flags);
                status = readl(config->ioaddr + STATUS_REG);
                spin_unlock_irqrestore(&config->lock, flags);
                if ((status & STATUS_BUSY) == 0)
                        break;
                /* check status busy, after each msec */
                msleep(1);
        }
}

static irqreturn_t spear_rtc_irq(int irq, void *dev_id)
{
        struct spear_rtc_config *config = dev_id;
        unsigned long events = 0;
        unsigned int irq_data;

        spin_lock(&config->lock);
        irq_data = readl(config->ioaddr + STATUS_REG);
        spin_unlock(&config->lock);

        if ((irq_data & RTC_INT_MASK)) {
                spear_rtc_clear_interrupt(config);
                events = RTC_IRQF | RTC_AF;
                rtc_update_irq(config->rtc, 1, events);
                return IRQ_HANDLED;
        } else
                return IRQ_NONE;

}

static void tm2bcd(struct rtc_time *tm)
{
        tm->tm_sec = bin2bcd(tm->tm_sec);
        tm->tm_min = bin2bcd(tm->tm_min);
        tm->tm_hour = bin2bcd(tm->tm_hour);
        tm->tm_mday = bin2bcd(tm->tm_mday);
        tm->tm_mon = bin2bcd(tm->tm_mon + 1);
        tm->tm_year = bin2bcd(tm->tm_year);
}

static void bcd2tm(struct rtc_time *tm)
{
        tm->tm_sec = bcd2bin(tm->tm_sec);
        tm->tm_min = bcd2bin(tm->tm_min);
        tm->tm_hour = bcd2bin(tm->tm_hour);
        tm->tm_mday = bcd2bin(tm->tm_mday);
        tm->tm_mon = bcd2bin(tm->tm_mon) - 1;
        /* epoch == 1900 */
        tm->tm_year = bcd2bin(tm->tm_year);
}

/*
 * spear_rtc_read_time - set the time
 * @dev: rtc device in use
 * @tm: holds date and time
 *
 * This function read time and date. On success it will return 0
 * otherwise -ve error is returned.
 */
static int spear_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        struct spear_rtc_config *config = dev_get_drvdata(dev);
        unsigned int time, date;

        /* we don't report wday/yday/isdst ... */
        rtc_wait_not_busy(config);

        do {
                time = readl(config->ioaddr + TIME_REG);
                date = readl(config->ioaddr + DATE_REG);
        } while (time == readl(config->ioaddr + TIME_REG));
        tm->tm_sec = (time >> SECOND_SHIFT) & SECOND_MASK;
        tm->tm_min = (time >> MINUTE_SHIFT) & MIN_MASK;
        tm->tm_hour = (time >> HOUR_SHIFT) & HOUR_MASK;
        tm->tm_mday = (date >> MDAY_SHIFT) & DAY_MASK;
        tm->tm_mon = (date >> MONTH_SHIFT) & MONTH_MASK;
        tm->tm_year = (date >> YEAR_SHIFT) & YEAR_MASK;

        bcd2tm(tm);
        return 0;
}

/*
 * spear_rtc_set_time - set the time
 * @dev: rtc device in use
 * @tm: holds date and time
 *
 * This function set time and date. On success it will return 0
 * otherwise -ve error is returned.
 */
static int spear_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        struct spear_rtc_config *config = dev_get_drvdata(dev);
        unsigned int time, date;

        tm2bcd(tm);

        rtc_wait_not_busy(config);
        time = (tm->tm_sec << SECOND_SHIFT) | (tm->tm_min << MINUTE_SHIFT) |
                (tm->tm_hour << HOUR_SHIFT);
        date = (tm->tm_mday << MDAY_SHIFT) | (tm->tm_mon << MONTH_SHIFT) |
                (tm->tm_year << YEAR_SHIFT);
        writel(time, config->ioaddr + TIME_REG);
        writel(date, config->ioaddr + DATE_REG);

        return is_write_complete(config);
}

/*
 * spear_rtc_read_alarm - read the alarm time
 * @dev: rtc device in use
 * @alm: holds alarm date and time
 *
 * This function read alarm time and date. On success it will return 0
 * otherwise -ve error is returned.
 */
static int spear_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
        struct spear_rtc_config *config = dev_get_drvdata(dev);
        unsigned int time, date;

        rtc_wait_not_busy(config);

        time = readl(config->ioaddr + ALARM_TIME_REG);
        date = readl(config->ioaddr + ALARM_DATE_REG);
        alm->time.tm_sec = (time >> SECOND_SHIFT) & SECOND_MASK;
        alm->time.tm_min = (time >> MINUTE_SHIFT) & MIN_MASK;
        alm->time.tm_hour = (time >> HOUR_SHIFT) & HOUR_MASK;
        alm->time.tm_mday = (date >> MDAY_SHIFT) & DAY_MASK;
        alm->time.tm_mon = (date >> MONTH_SHIFT) & MONTH_MASK;
        alm->time.tm_year = (date >> YEAR_SHIFT) & YEAR_MASK;

        bcd2tm(&alm->time);
        alm->enabled = readl(config->ioaddr + CTRL_REG) & INT_ENABLE;

        return 0;
}

/*
 * spear_rtc_set_alarm - set the alarm time
 * @dev: rtc device in use
 * @alm: holds alarm date and time
 *
 * This function set alarm time and date. On success it will return 0
 * otherwise -ve error is returned.
 */
static int spear_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
        struct spear_rtc_config *config = dev_get_drvdata(dev);
        unsigned int time, date;
        int err;

        tm2bcd(&alm->time);

        rtc_wait_not_busy(config);

        time = (alm->time.tm_sec << SECOND_SHIFT) | (alm->time.tm_min <<
                        MINUTE_SHIFT) | (alm->time.tm_hour << HOUR_SHIFT);
        date = (alm->time.tm_mday << MDAY_SHIFT) | (alm->time.tm_mon <<
                        MONTH_SHIFT) | (alm->time.tm_year << YEAR_SHIFT);

        writel(time, config->ioaddr + ALARM_TIME_REG);
        writel(date, config->ioaddr + ALARM_DATE_REG);
        err = is_write_complete(config);
        if (err < 0)
                return err;

        if (alm->enabled)
                spear_rtc_enable_interrupt(config);
        else
                spear_rtc_disable_interrupt(config);

        return 0;
}

static int spear_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
        struct spear_rtc_config *config = dev_get_drvdata(dev);
        int ret = 0;

        spear_rtc_clear_interrupt(config);

        switch (enabled) {
        case 0:
                /* alarm off */
                spear_rtc_disable_interrupt(config);
                break;
        case 1:
                /* alarm on */
                spear_rtc_enable_interrupt(config);
                break;
        default:
                ret = -EINVAL;
                break;
        }

        return ret;
}

static const struct rtc_class_ops spear_rtc_ops = {
        .read_time = spear_rtc_read_time,
        .set_time = spear_rtc_set_time,
        .read_alarm = spear_rtc_read_alarm,
        .set_alarm = spear_rtc_set_alarm,
        .alarm_irq_enable = spear_alarm_irq_enable,
};

static int spear_rtc_probe(struct platform_device *pdev)
{
        struct spear_rtc_config *config;
        int status = 0;
        int irq;

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

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

        /* alarm irqs */
        irq = platform_get_irq(pdev, 0);
        if (irq < 0)
                return irq;

        status = devm_request_irq(&pdev->dev, irq, spear_rtc_irq, 0, pdev->name,
                        config);
        if (status) {
                dev_err(&pdev->dev, "Alarm interrupt IRQ%d already claimed\n",
                                irq);
                return status;
        }

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

        config->clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(config->clk))
                return PTR_ERR(config->clk);

        status = clk_prepare_enable(config->clk);
        if (status < 0)
                return status;

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

        config->rtc->ops = &spear_rtc_ops;
        config->rtc->range_min = RTC_TIMESTAMP_BEGIN_0000;
        config->rtc->range_max = RTC_TIMESTAMP_END_9999;

        status = devm_rtc_register_device(config->rtc);
        if (status)
                goto err_disable_clock;

        if (!device_can_wakeup(&pdev->dev))
                device_init_wakeup(&pdev->dev, true);

        return 0;

err_disable_clock:
        clk_disable_unprepare(config->clk);

        return status;
}

static void spear_rtc_remove(struct platform_device *pdev)
{
        struct spear_rtc_config *config = platform_get_drvdata(pdev);

        spear_rtc_disable_interrupt(config);
        clk_disable_unprepare(config->clk);
        device_init_wakeup(&pdev->dev, false);
}

#ifdef CONFIG_PM_SLEEP
static int spear_rtc_suspend(struct device *dev)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct spear_rtc_config *config = platform_get_drvdata(pdev);
        int irq;

        irq = platform_get_irq(pdev, 0);
        if (device_may_wakeup(&pdev->dev)) {
                if (!enable_irq_wake(irq))
                        config->irq_wake = 1;
        } else {
                spear_rtc_disable_interrupt(config);
                clk_disable(config->clk);
        }

        return 0;
}

static int spear_rtc_resume(struct device *dev)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct spear_rtc_config *config = platform_get_drvdata(pdev);
        int irq;

        irq = platform_get_irq(pdev, 0);

        if (device_may_wakeup(&pdev->dev)) {
                if (config->irq_wake) {
                        disable_irq_wake(irq);
                        config->irq_wake = 0;
                }
        } else {
                clk_enable(config->clk);
                spear_rtc_enable_interrupt(config);
        }

        return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(spear_rtc_pm_ops, spear_rtc_suspend, spear_rtc_resume);

static void spear_rtc_shutdown(struct platform_device *pdev)
{
        struct spear_rtc_config *config = platform_get_drvdata(pdev);

        spear_rtc_disable_interrupt(config);
        clk_disable(config->clk);
}

#ifdef CONFIG_OF
static const struct of_device_id spear_rtc_id_table[] = {
        { .compatible = "st,spear600-rtc" },
        {}
};
MODULE_DEVICE_TABLE(of, spear_rtc_id_table);
#endif

static struct platform_driver spear_rtc_driver = {
        .probe = spear_rtc_probe,
        .remove = spear_rtc_remove,
        .shutdown = spear_rtc_shutdown,
        .driver = {
                .name = "rtc-spear",
                .pm = &spear_rtc_pm_ops,
                .of_match_table = of_match_ptr(spear_rtc_id_table),
        },
};

module_platform_driver(spear_rtc_driver);

MODULE_ALIAS("platform:rtc-spear");
MODULE_AUTHOR("Rajeev Kumar <rajeev-dlh.kumar@st.com>");
MODULE_DESCRIPTION("ST SPEAr Realtime Clock Driver (RTC)");
MODULE_LICENSE("GPL");