// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * DS1286 Real Time Clock interface for Linux
 *
 * Copyright (C) 1998, 1999, 2000 Ralf Baechle
 * Copyright (C) 2008 Thomas Bogendoerfer
 *
 * Based on code written by Paul Gortmaker.
 */

#include <linux/module.h>
#include <linux/rtc.h>
#include <linux/platform_device.h>
#include <linux/bcd.h>
#include <linux/rtc/ds1286.h>
#include <linux/io.h>
#include <linux/slab.h>

struct ds1286_priv {
        struct rtc_device *rtc;
        u32 __iomem *rtcregs;
        spinlock_t lock;
};

static inline u8 ds1286_rtc_read(struct ds1286_priv *priv, int reg)
{
        return __raw_readl(&priv->rtcregs[reg]) & 0xff;
}

static inline void ds1286_rtc_write(struct ds1286_priv *priv, u8 data, int reg)
{
        __raw_writel(data, &priv->rtcregs[reg]);
}


static int ds1286_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
        struct ds1286_priv *priv = dev_get_drvdata(dev);
        unsigned long flags;
        unsigned char val;

        /* Allow or mask alarm interrupts */
        spin_lock_irqsave(&priv->lock, flags);
        val = ds1286_rtc_read(priv, RTC_CMD);
        if (enabled)
                val &=  ~RTC_TDM;
        else
                val |=  RTC_TDM;
        ds1286_rtc_write(priv, val, RTC_CMD);
        spin_unlock_irqrestore(&priv->lock, flags);

        return 0;
}

#ifdef CONFIG_RTC_INTF_DEV

static int ds1286_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
{
        struct ds1286_priv *priv = dev_get_drvdata(dev);
        unsigned long flags;
        unsigned char val;

        switch (cmd) {
        case RTC_WIE_OFF:
                /* Mask watchdog int. enab. bit */
                spin_lock_irqsave(&priv->lock, flags);
                val = ds1286_rtc_read(priv, RTC_CMD);
                val |= RTC_WAM;
                ds1286_rtc_write(priv, val, RTC_CMD);
                spin_unlock_irqrestore(&priv->lock, flags);
                break;
        case RTC_WIE_ON:
                /* Allow watchdog interrupts.   */
                spin_lock_irqsave(&priv->lock, flags);
                val = ds1286_rtc_read(priv, RTC_CMD);
                val &= ~RTC_WAM;
                ds1286_rtc_write(priv, val, RTC_CMD);
                spin_unlock_irqrestore(&priv->lock, flags);
                break;
        default:
                return -ENOIOCTLCMD;
        }
        return 0;
}

#else
#define ds1286_ioctl    NULL
#endif

#ifdef CONFIG_PROC_FS

static int ds1286_proc(struct device *dev, struct seq_file *seq)
{
        struct ds1286_priv *priv = dev_get_drvdata(dev);
        unsigned char month, cmd, amode;
        const char *s;

        month = ds1286_rtc_read(priv, RTC_MONTH);
        seq_printf(seq,
                   "oscillator\t: %s\n"
                   "square_wave\t: %s\n",
                   (month & RTC_EOSC) ? "disabled" : "enabled",
                   (month & RTC_ESQW) ? "disabled" : "enabled");

        amode = ((ds1286_rtc_read(priv, RTC_MINUTES_ALARM) & 0x80) >> 5) |
                ((ds1286_rtc_read(priv, RTC_HOURS_ALARM) & 0x80) >> 6) |
                ((ds1286_rtc_read(priv, RTC_DAY_ALARM) & 0x80) >> 7);
        switch (amode) {
        case 7:
                s = "each minute";
                break;
        case 3:
                s = "minutes match";
                break;
        case 1:
                s = "hours and minutes match";
                break;
        case 0:
                s = "days, hours and minutes match";
                break;
        default:
                s = "invalid";
                break;
        }
        seq_printf(seq, "alarm_mode\t: %s\n", s);

        cmd = ds1286_rtc_read(priv, RTC_CMD);
        seq_printf(seq,
                   "alarm_enable\t: %s\n"
                   "wdog_alarm\t: %s\n"
                   "alarm_mask\t: %s\n"
                   "wdog_alarm_mask\t: %s\n"
                   "interrupt_mode\t: %s\n"
                   "INTB_mode\t: %s_active\n"
                   "interrupt_pins\t: %s\n",
                   (cmd & RTC_TDF) ? "yes" : "no",
                   (cmd & RTC_WAF) ? "yes" : "no",
                   (cmd & RTC_TDM) ? "disabled" : "enabled",
                   (cmd & RTC_WAM) ? "disabled" : "enabled",
                   (cmd & RTC_PU_LVL) ? "pulse" : "level",
                   (cmd & RTC_IBH_LO) ? "low" : "high",
                   (cmd & RTC_IPSW) ? "unswapped" : "swapped");
        return 0;
}

#else
#define ds1286_proc     NULL
#endif

static int ds1286_read_time(struct device *dev, struct rtc_time *tm)
{
        struct ds1286_priv *priv = dev_get_drvdata(dev);
        unsigned char save_control;
        unsigned long flags;
        unsigned long uip_watchdog = jiffies;

        /*
         * read RTC once any update in progress is done. The update
         * can take just over 2ms. We wait 10 to 20ms. There is no need to
         * to poll-wait (up to 1s - eeccch) for the falling edge of RTC_UIP.
         * If you need to know *exactly* when a second has started, enable
         * periodic update complete interrupts, (via ioctl) and then
         * immediately read /dev/rtc which will block until you get the IRQ.
         * Once the read clears, read the RTC time (again via ioctl). Easy.
         */

        if (ds1286_rtc_read(priv, RTC_CMD) & RTC_TE)
                while (time_before(jiffies, uip_watchdog + 2*HZ/100))
                        barrier();

        /*
         * Only the values that we read from the RTC are set. We leave
         * tm_wday, tm_yday and tm_isdst untouched. Even though the
         * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
         * by the RTC when initially set to a non-zero value.
         */
        spin_lock_irqsave(&priv->lock, flags);
        save_control = ds1286_rtc_read(priv, RTC_CMD);
        ds1286_rtc_write(priv, (save_control|RTC_TE), RTC_CMD);

        tm->tm_sec = ds1286_rtc_read(priv, RTC_SECONDS);
        tm->tm_min = ds1286_rtc_read(priv, RTC_MINUTES);
        tm->tm_hour = ds1286_rtc_read(priv, RTC_HOURS) & 0x3f;
        tm->tm_mday = ds1286_rtc_read(priv, RTC_DATE);
        tm->tm_mon = ds1286_rtc_read(priv, RTC_MONTH) & 0x1f;
        tm->tm_year = ds1286_rtc_read(priv, RTC_YEAR);

        ds1286_rtc_write(priv, save_control, RTC_CMD);
        spin_unlock_irqrestore(&priv->lock, flags);

        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);
        tm->tm_year = bcd2bin(tm->tm_year);

        /*
         * Account for differences between how the RTC uses the values
         * and how they are defined in a struct rtc_time;
         */
        if (tm->tm_year < 45)
                tm->tm_year += 30;
        tm->tm_year += 40;
        if (tm->tm_year < 70)
                tm->tm_year += 100;

        tm->tm_mon--;

        return 0;
}

static int ds1286_set_time(struct device *dev, struct rtc_time *tm)
{
        struct ds1286_priv *priv = dev_get_drvdata(dev);
        unsigned char mon, day, hrs, min, sec;
        unsigned char save_control;
        unsigned int yrs;
        unsigned long flags;

        yrs = tm->tm_year + 1900;
        mon = tm->tm_mon + 1;   /* tm_mon starts at zero */
        day = tm->tm_mday;
        hrs = tm->tm_hour;
        min = tm->tm_min;
        sec = tm->tm_sec;

        if (yrs < 1970)
                return -EINVAL;

        yrs -= 1940;
        if (yrs > 255)    /* They are unsigned */
                return -EINVAL;

        if (yrs >= 100)
                yrs -= 100;

        sec = bin2bcd(sec);
        min = bin2bcd(min);
        hrs = bin2bcd(hrs);
        day = bin2bcd(day);
        mon = bin2bcd(mon);
        yrs = bin2bcd(yrs);

        spin_lock_irqsave(&priv->lock, flags);
        save_control = ds1286_rtc_read(priv, RTC_CMD);
        ds1286_rtc_write(priv, (save_control|RTC_TE), RTC_CMD);

        ds1286_rtc_write(priv, yrs, RTC_YEAR);
        ds1286_rtc_write(priv, mon, RTC_MONTH);
        ds1286_rtc_write(priv, day, RTC_DATE);
        ds1286_rtc_write(priv, hrs, RTC_HOURS);
        ds1286_rtc_write(priv, min, RTC_MINUTES);
        ds1286_rtc_write(priv, sec, RTC_SECONDS);
        ds1286_rtc_write(priv, 0, RTC_HUNDREDTH_SECOND);

        ds1286_rtc_write(priv, save_control, RTC_CMD);
        spin_unlock_irqrestore(&priv->lock, flags);
        return 0;
}

static int ds1286_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
        struct ds1286_priv *priv = dev_get_drvdata(dev);
        unsigned long flags;

        /*
         * Only the values that we read from the RTC are set. That
         * means only tm_wday, tm_hour, tm_min.
         */
        spin_lock_irqsave(&priv->lock, flags);
        alm->time.tm_min = ds1286_rtc_read(priv, RTC_MINUTES_ALARM) & 0x7f;
        alm->time.tm_hour = ds1286_rtc_read(priv, RTC_HOURS_ALARM)  & 0x1f;
        alm->time.tm_wday = ds1286_rtc_read(priv, RTC_DAY_ALARM)    & 0x07;
        ds1286_rtc_read(priv, RTC_CMD);
        spin_unlock_irqrestore(&priv->lock, flags);

        alm->time.tm_min = bcd2bin(alm->time.tm_min);
        alm->time.tm_hour = bcd2bin(alm->time.tm_hour);
        alm->time.tm_sec = 0;
        return 0;
}

static int ds1286_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
        struct ds1286_priv *priv = dev_get_drvdata(dev);
        unsigned char hrs, min, sec;

        hrs = alm->time.tm_hour;
        min = alm->time.tm_min;
        sec = alm->time.tm_sec;

        if (hrs >= 24)
                hrs = 0xff;

        if (min >= 60)
                min = 0xff;

        if (sec != 0)
                return -EINVAL;

        min = bin2bcd(min);
        hrs = bin2bcd(hrs);

        spin_lock(&priv->lock);
        ds1286_rtc_write(priv, hrs, RTC_HOURS_ALARM);
        ds1286_rtc_write(priv, min, RTC_MINUTES_ALARM);
        spin_unlock(&priv->lock);

        return 0;
}

static const struct rtc_class_ops ds1286_ops = {
        .ioctl          = ds1286_ioctl,
        .proc           = ds1286_proc,
        .read_time      = ds1286_read_time,
        .set_time       = ds1286_set_time,
        .read_alarm     = ds1286_read_alarm,
        .set_alarm      = ds1286_set_alarm,
        .alarm_irq_enable = ds1286_alarm_irq_enable,
};

static int ds1286_probe(struct platform_device *pdev)
{
        struct rtc_device *rtc;
        struct ds1286_priv *priv;

        priv = devm_kzalloc(&pdev->dev, sizeof(struct ds1286_priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        priv->rtcregs = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(priv->rtcregs))
                return PTR_ERR(priv->rtcregs);

        spin_lock_init(&priv->lock);
        platform_set_drvdata(pdev, priv);
        rtc = devm_rtc_device_register(&pdev->dev, "ds1286", &ds1286_ops,
                                        THIS_MODULE);
        if (IS_ERR(rtc))
                return PTR_ERR(rtc);
        priv->rtc = rtc;
        return 0;
}

static struct platform_driver ds1286_platform_driver = {
        .driver         = {
                .name   = "rtc-ds1286",
        },
        .probe          = ds1286_probe,
};

module_platform_driver(ds1286_platform_driver);

MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
MODULE_DESCRIPTION("DS1286 RTC driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:rtc-ds1286");