// SPDX-License-Identifier: GPL-2.0-only
/*
 * Real-time clock driver for MPC5121
 *
 * Copyright 2007, Domen Puncer <domen.puncer@telargo.com>
 * Copyright 2008, Freescale Semiconductor, Inc. All rights reserved.
 * Copyright 2011, Dmitry Eremin-Solenikov
 */

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

struct mpc5121_rtc_regs {
        u8 set_time;            /* RTC + 0x00 */
        u8 hour_set;            /* RTC + 0x01 */
        u8 minute_set;          /* RTC + 0x02 */
        u8 second_set;          /* RTC + 0x03 */

        u8 set_date;            /* RTC + 0x04 */
        u8 month_set;           /* RTC + 0x05 */
        u8 weekday_set;         /* RTC + 0x06 */
        u8 date_set;            /* RTC + 0x07 */

        u8 write_sw;            /* RTC + 0x08 */
        u8 sw_set;              /* RTC + 0x09 */
        u16 year_set;           /* RTC + 0x0a */

        u8 alm_enable;          /* RTC + 0x0c */
        u8 alm_hour_set;        /* RTC + 0x0d */
        u8 alm_min_set;         /* RTC + 0x0e */
        u8 int_enable;          /* RTC + 0x0f */

        u8 reserved1;
        u8 hour;                /* RTC + 0x11 */
        u8 minute;              /* RTC + 0x12 */
        u8 second;              /* RTC + 0x13 */

        u8 month;               /* RTC + 0x14 */
        u8 wday_mday;           /* RTC + 0x15 */
        u16 year;               /* RTC + 0x16 */

        u8 int_alm;             /* RTC + 0x18 */
        u8 int_sw;              /* RTC + 0x19 */
        u8 alm_status;          /* RTC + 0x1a */
        u8 sw_minute;           /* RTC + 0x1b */

        u8 bus_error_1;         /* RTC + 0x1c */
        u8 int_day;             /* RTC + 0x1d */
        u8 int_min;             /* RTC + 0x1e */
        u8 int_sec;             /* RTC + 0x1f */

        /*
         * target_time:
         *      intended to be used for hibernation but hibernation
         *      does not work on silicon rev 1.5 so use it for non-volatile
         *      storage of offset between the actual_time register and linux
         *      time
         */
        u32 target_time;        /* RTC + 0x20 */
        /*
         * actual_time:
         *      readonly time since VBAT_RTC was last connected
         */
        u32 actual_time;        /* RTC + 0x24 */
        u32 keep_alive;         /* RTC + 0x28 */
};

struct mpc5121_rtc_data {
        unsigned irq;
        unsigned irq_periodic;
        struct mpc5121_rtc_regs __iomem *regs;
        struct rtc_device *rtc;
        struct rtc_wkalrm wkalarm;
};

/*
 * Update second/minute/hour registers.
 *
 * This is just so alarm will work.
 */
static void mpc5121_rtc_update_smh(struct mpc5121_rtc_regs __iomem *regs,
                                   struct rtc_time *tm)
{
        out_8(&regs->second_set, tm->tm_sec);
        out_8(&regs->minute_set, tm->tm_min);
        out_8(&regs->hour_set, tm->tm_hour);

        /* set time sequence */
        out_8(&regs->set_time, 0x1);
        out_8(&regs->set_time, 0x3);
        out_8(&regs->set_time, 0x1);
        out_8(&regs->set_time, 0x0);
}

static int mpc5121_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        struct mpc5121_rtc_data *rtc = dev_get_drvdata(dev);
        struct mpc5121_rtc_regs __iomem *regs = rtc->regs;
        unsigned long now;

        /*
         * linux time is actual_time plus the offset saved in target_time
         */
        now = in_be32(&regs->actual_time) + in_be32(&regs->target_time);

        rtc_time64_to_tm(now, tm);

        /*
         * update second minute hour registers
         * so alarms will work
         */
        mpc5121_rtc_update_smh(regs, tm);

        return 0;
}

static int mpc5121_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        struct mpc5121_rtc_data *rtc = dev_get_drvdata(dev);
        struct mpc5121_rtc_regs __iomem *regs = rtc->regs;
        unsigned long now;

        /*
         * The actual_time register is read only so we write the offset
         * between it and linux time to the target_time register.
         */
        now = rtc_tm_to_time64(tm);
        out_be32(&regs->target_time, now - in_be32(&regs->actual_time));

        /*
         * update second minute hour registers
         * so alarms will work
         */
        mpc5121_rtc_update_smh(regs, tm);

        return 0;
}

static int mpc5200_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        struct mpc5121_rtc_data *rtc = dev_get_drvdata(dev);
        struct mpc5121_rtc_regs __iomem *regs = rtc->regs;
        int tmp;

        tm->tm_sec = in_8(&regs->second);
        tm->tm_min = in_8(&regs->minute);

        /* 12 hour format? */
        if (in_8(&regs->hour) & 0x20)
                tm->tm_hour = (in_8(&regs->hour) >> 1) +
                        (in_8(&regs->hour) & 1 ? 12 : 0);
        else
                tm->tm_hour = in_8(&regs->hour);

        tmp = in_8(&regs->wday_mday);
        tm->tm_mday = tmp & 0x1f;
        tm->tm_mon = in_8(&regs->month) - 1;
        tm->tm_year = in_be16(&regs->year) - 1900;
        tm->tm_wday = (tmp >> 5) % 7;
        tm->tm_yday = rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year);
        tm->tm_isdst = 0;

        return 0;
}

static int mpc5200_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        struct mpc5121_rtc_data *rtc = dev_get_drvdata(dev);
        struct mpc5121_rtc_regs __iomem *regs = rtc->regs;

        mpc5121_rtc_update_smh(regs, tm);

        /* date */
        out_8(&regs->month_set, tm->tm_mon + 1);
        out_8(&regs->weekday_set, tm->tm_wday ? tm->tm_wday : 7);
        out_8(&regs->date_set, tm->tm_mday);
        out_be16(&regs->year_set, tm->tm_year + 1900);

        /* set date sequence */
        out_8(&regs->set_date, 0x1);
        out_8(&regs->set_date, 0x3);
        out_8(&regs->set_date, 0x1);
        out_8(&regs->set_date, 0x0);

        return 0;
}

static int mpc5121_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
        struct mpc5121_rtc_data *rtc = dev_get_drvdata(dev);
        struct mpc5121_rtc_regs __iomem *regs = rtc->regs;

        *alarm = rtc->wkalarm;

        alarm->pending = in_8(&regs->alm_status);

        return 0;
}

static int mpc5121_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
        struct mpc5121_rtc_data *rtc = dev_get_drvdata(dev);
        struct mpc5121_rtc_regs __iomem *regs = rtc->regs;

        alarm->time.tm_mday = -1;
        alarm->time.tm_mon = -1;
        alarm->time.tm_year = -1;

        out_8(&regs->alm_min_set, alarm->time.tm_min);
        out_8(&regs->alm_hour_set, alarm->time.tm_hour);

        out_8(&regs->alm_enable, alarm->enabled);

        rtc->wkalarm = *alarm;
        return 0;
}

static irqreturn_t mpc5121_rtc_handler(int irq, void *dev)
{
        struct mpc5121_rtc_data *rtc = dev_get_drvdata((struct device *)dev);
        struct mpc5121_rtc_regs __iomem *regs = rtc->regs;

        if (in_8(&regs->int_alm)) {
                /* acknowledge and clear status */
                out_8(&regs->int_alm, 1);
                out_8(&regs->alm_status, 1);

                rtc_update_irq(rtc->rtc, 1, RTC_IRQF | RTC_AF);
                return IRQ_HANDLED;
        }

        return IRQ_NONE;
}

static irqreturn_t mpc5121_rtc_handler_upd(int irq, void *dev)
{
        struct mpc5121_rtc_data *rtc = dev_get_drvdata((struct device *)dev);
        struct mpc5121_rtc_regs __iomem *regs = rtc->regs;

        if (in_8(&regs->int_sec) && (in_8(&regs->int_enable) & 0x1)) {
                /* acknowledge */
                out_8(&regs->int_sec, 1);

                rtc_update_irq(rtc->rtc, 1, RTC_IRQF | RTC_UF);
                return IRQ_HANDLED;
        }

        return IRQ_NONE;
}

static int mpc5121_rtc_alarm_irq_enable(struct device *dev,
                                        unsigned int enabled)
{
        struct mpc5121_rtc_data *rtc = dev_get_drvdata(dev);
        struct mpc5121_rtc_regs __iomem *regs = rtc->regs;
        int val;

        if (enabled)
                val = 1;
        else
                val = 0;

        out_8(&regs->alm_enable, val);
        rtc->wkalarm.enabled = val;

        return 0;
}

static const struct rtc_class_ops mpc5121_rtc_ops = {
        .read_time = mpc5121_rtc_read_time,
        .set_time = mpc5121_rtc_set_time,
        .read_alarm = mpc5121_rtc_read_alarm,
        .set_alarm = mpc5121_rtc_set_alarm,
        .alarm_irq_enable = mpc5121_rtc_alarm_irq_enable,
};

static const struct rtc_class_ops mpc5200_rtc_ops = {
        .read_time = mpc5200_rtc_read_time,
        .set_time = mpc5200_rtc_set_time,
        .read_alarm = mpc5121_rtc_read_alarm,
        .set_alarm = mpc5121_rtc_set_alarm,
        .alarm_irq_enable = mpc5121_rtc_alarm_irq_enable,
};

static int mpc5121_rtc_probe(struct platform_device *op)
{
        struct mpc5121_rtc_data *rtc;
        int err = 0;

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

        rtc->regs = devm_platform_ioremap_resource(op, 0);
        if (IS_ERR(rtc->regs)) {
                dev_err(&op->dev, "%s: couldn't map io space\n", __func__);
                return PTR_ERR(rtc->regs);
        }

        device_init_wakeup(&op->dev, true);

        platform_set_drvdata(op, rtc);

        rtc->irq = irq_of_parse_and_map(op->dev.of_node, 1);
        err = devm_request_irq(&op->dev, rtc->irq, mpc5121_rtc_handler, 0,
                               "mpc5121-rtc", &op->dev);
        if (err) {
                dev_err(&op->dev, "%s: could not request irq: %i\n",
                                                        __func__, rtc->irq);
                goto out_dispose;
        }

        rtc->irq_periodic = irq_of_parse_and_map(op->dev.of_node, 0);
        err = devm_request_irq(&op->dev, rtc->irq_periodic,
                               mpc5121_rtc_handler_upd, 0, "mpc5121-rtc_upd",
                               &op->dev);
        if (err) {
                dev_err(&op->dev, "%s: could not request irq: %i\n",
                                                __func__, rtc->irq_periodic);
                goto out_dispose2;
        }

        rtc->rtc = devm_rtc_allocate_device(&op->dev);
        if (IS_ERR(rtc->rtc)) {
                err = PTR_ERR(rtc->rtc);
                goto out_dispose2;
        }

        rtc->rtc->ops = &mpc5200_rtc_ops;
        set_bit(RTC_FEATURE_ALARM_RES_MINUTE, rtc->rtc->features);
        clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->rtc->features);
        rtc->rtc->range_min = RTC_TIMESTAMP_BEGIN_0000;
        rtc->rtc->range_max = 65733206399ULL; /* 4052-12-31 23:59:59 */

        if (of_device_is_compatible(op->dev.of_node, "fsl,mpc5121-rtc")) {
                u32 ka;
                ka = in_be32(&rtc->regs->keep_alive);
                if (ka & 0x02) {
                        dev_warn(&op->dev,
                                "mpc5121-rtc: Battery or oscillator failure!\n");
                        out_be32(&rtc->regs->keep_alive, ka);
                }
                rtc->rtc->ops = &mpc5121_rtc_ops;
                /*
                 * This is a limitation of the driver that abuses the target
                 * time register, the actual maximum year for the mpc5121 is
                 * also 4052.
                 */
                rtc->rtc->range_min = 0;
                rtc->rtc->range_max = U32_MAX;
        }

        err = devm_rtc_register_device(rtc->rtc);
        if (err)
                goto out_dispose2;

        return 0;

out_dispose2:
        irq_dispose_mapping(rtc->irq_periodic);
out_dispose:
        irq_dispose_mapping(rtc->irq);

        return err;
}

static void mpc5121_rtc_remove(struct platform_device *op)
{
        struct mpc5121_rtc_data *rtc = platform_get_drvdata(op);
        struct mpc5121_rtc_regs __iomem *regs = rtc->regs;

        /* disable interrupt, so there are no nasty surprises */
        out_8(&regs->alm_enable, 0);
        out_8(&regs->int_enable, in_8(&regs->int_enable) & ~0x1);

        irq_dispose_mapping(rtc->irq);
        irq_dispose_mapping(rtc->irq_periodic);
}

#ifdef CONFIG_OF
static const struct of_device_id mpc5121_rtc_match[] = {
        { .compatible = "fsl,mpc5121-rtc", },
        { .compatible = "fsl,mpc5200-rtc", },
        {},
};
MODULE_DEVICE_TABLE(of, mpc5121_rtc_match);
#endif

static struct platform_driver mpc5121_rtc_driver = {
        .driver = {
                .name = "mpc5121-rtc",
                .of_match_table = of_match_ptr(mpc5121_rtc_match),
        },
        .probe = mpc5121_rtc_probe,
        .remove = mpc5121_rtc_remove,
};

module_platform_driver(mpc5121_rtc_driver);

MODULE_DESCRIPTION("Freescale MPC5121 built-in RTC driver");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("John Rigby <jcrigby@gmail.com>");