// SPDX-License-Identifier: GPL-2.0-only
/* drivers/rtc/rtc-s3c.c
 *
 * Copyright (c) 2010 Samsung Electronics Co., Ltd.
 *              http://www.samsung.com/
 *
 * Copyright (c) 2004,2006 Simtec Electronics
 *      Ben Dooks, <ben@simtec.co.uk>
 *      http://armlinux.simtec.co.uk/
 *
 * S3C2410/S3C2440/S3C24XX Internal RTC Driver
*/

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/interrupt.h>
#include <linux/rtc.h>
#include <linux/bcd.h>
#include <linux/clk.h>
#include <linux/log2.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/uaccess.h>
#include <linux/io.h>

#include <asm/irq.h>
#include "rtc-s3c.h"

struct s3c_rtc {
        struct device *dev;
        struct rtc_device *rtc;

        void __iomem *base;
        struct clk *rtc_clk;
        struct clk *rtc_src_clk;
        bool alarm_enabled;

        const struct s3c_rtc_data *data;

        int irq_alarm;
        spinlock_t alarm_lock;

        bool wake_en;
};

struct s3c_rtc_data {
        bool needs_src_clk;

        void (*irq_handler) (struct s3c_rtc *info, int mask);
        void (*enable) (struct s3c_rtc *info);
        void (*disable) (struct s3c_rtc *info);
};

static int s3c_rtc_enable_clk(struct s3c_rtc *info)
{
        int ret;

        ret = clk_enable(info->rtc_clk);
        if (ret)
                return ret;

        if (info->data->needs_src_clk) {
                ret = clk_enable(info->rtc_src_clk);
                if (ret) {
                        clk_disable(info->rtc_clk);
                        return ret;
                }
        }
        return 0;
}

static void s3c_rtc_disable_clk(struct s3c_rtc *info)
{
        if (info->data->needs_src_clk)
                clk_disable(info->rtc_src_clk);
        clk_disable(info->rtc_clk);
}

/* IRQ Handler */
static irqreturn_t s3c_rtc_alarmirq(int irq, void *id)
{
        struct s3c_rtc *info = (struct s3c_rtc *)id;

        if (info->data->irq_handler)
                info->data->irq_handler(info, S3C2410_INTP_ALM);

        return IRQ_HANDLED;
}

/* Update control registers */
static int s3c_rtc_setaie(struct device *dev, unsigned int enabled)
{
        struct s3c_rtc *info = dev_get_drvdata(dev);
        unsigned long flags;
        unsigned int tmp;
        int ret;

        dev_dbg(info->dev, "%s: aie=%d\n", __func__, enabled);

        ret = s3c_rtc_enable_clk(info);
        if (ret)
                return ret;

        tmp = readb(info->base + S3C2410_RTCALM) & ~S3C2410_RTCALM_ALMEN;

        if (enabled)
                tmp |= S3C2410_RTCALM_ALMEN;

        writeb(tmp, info->base + S3C2410_RTCALM);

        spin_lock_irqsave(&info->alarm_lock, flags);

        if (info->alarm_enabled && !enabled)
                s3c_rtc_disable_clk(info);
        else if (!info->alarm_enabled && enabled)
                ret = s3c_rtc_enable_clk(info);

        info->alarm_enabled = enabled;
        spin_unlock_irqrestore(&info->alarm_lock, flags);

        s3c_rtc_disable_clk(info);

        return ret;
}

/* Read time from RTC and convert it from BCD */
static int s3c_rtc_read_time(struct s3c_rtc *info, struct rtc_time *tm)
{
        unsigned int have_retried = 0;
        int ret;

        ret = s3c_rtc_enable_clk(info);
        if (ret)
                return ret;

retry_get_time:
        tm->tm_min  = readb(info->base + S3C2410_RTCMIN);
        tm->tm_hour = readb(info->base + S3C2410_RTCHOUR);
        tm->tm_mday = readb(info->base + S3C2410_RTCDATE);
        tm->tm_mon  = readb(info->base + S3C2410_RTCMON);
        tm->tm_year = readb(info->base + S3C2410_RTCYEAR);
        tm->tm_sec  = readb(info->base + S3C2410_RTCSEC);

        /*
         * The only way to work out whether the system was mid-update
         * when we read it is to check the second counter, and if it
         * is zero, then we re-try the entire read
         */
        if (tm->tm_sec == 0 && !have_retried) {
                have_retried = 1;
                goto retry_get_time;
        }

        s3c_rtc_disable_clk(info);

        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);

        return 0;
}

/* Convert time to BCD and write it to RTC */
static int s3c_rtc_write_time(struct s3c_rtc *info, const struct rtc_time *tm)
{
        int ret;

        ret = s3c_rtc_enable_clk(info);
        if (ret)
                return ret;

        writeb(bin2bcd(tm->tm_sec),  info->base + S3C2410_RTCSEC);
        writeb(bin2bcd(tm->tm_min),  info->base + S3C2410_RTCMIN);
        writeb(bin2bcd(tm->tm_hour), info->base + S3C2410_RTCHOUR);
        writeb(bin2bcd(tm->tm_mday), info->base + S3C2410_RTCDATE);
        writeb(bin2bcd(tm->tm_mon),  info->base + S3C2410_RTCMON);
        writeb(bin2bcd(tm->tm_year), info->base + S3C2410_RTCYEAR);

        s3c_rtc_disable_clk(info);

        return 0;
}

static int s3c_rtc_gettime(struct device *dev, struct rtc_time *tm)
{
        struct s3c_rtc *info = dev_get_drvdata(dev);
        int ret;

        ret = s3c_rtc_read_time(info, tm);
        if (ret)
                return ret;

        /* Convert internal representation to actual date/time */
        tm->tm_year += 100;
        tm->tm_mon -= 1;

        dev_dbg(dev, "read time %ptR\n", tm);
        return 0;
}

static int s3c_rtc_settime(struct device *dev, struct rtc_time *tm)
{
        struct s3c_rtc *info = dev_get_drvdata(dev);
        struct rtc_time rtc_tm = *tm;

        dev_dbg(dev, "set time %ptR\n", tm);

        /*
         * Convert actual date/time to internal representation.
         * We get around Y2K by simply not supporting it.
         */
        rtc_tm.tm_year -= 100;
        rtc_tm.tm_mon += 1;

        return s3c_rtc_write_time(info, &rtc_tm);
}

static int s3c_rtc_getalarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        struct s3c_rtc *info = dev_get_drvdata(dev);
        struct rtc_time *alm_tm = &alrm->time;
        unsigned int alm_en;
        int ret;

        ret = s3c_rtc_enable_clk(info);
        if (ret)
                return ret;

        alm_tm->tm_sec  = readb(info->base + S3C2410_ALMSEC);
        alm_tm->tm_min  = readb(info->base + S3C2410_ALMMIN);
        alm_tm->tm_hour = readb(info->base + S3C2410_ALMHOUR);
        alm_tm->tm_mon  = readb(info->base + S3C2410_ALMMON);
        alm_tm->tm_mday = readb(info->base + S3C2410_ALMDATE);
        alm_tm->tm_year = readb(info->base + S3C2410_ALMYEAR);

        alm_en = readb(info->base + S3C2410_RTCALM);

        s3c_rtc_disable_clk(info);

        alrm->enabled = (alm_en & S3C2410_RTCALM_ALMEN) ? 1 : 0;

        dev_dbg(dev, "read alarm %d, %ptR\n", alm_en, alm_tm);

        /* decode the alarm enable field */
        if (alm_en & S3C2410_RTCALM_SECEN)
                alm_tm->tm_sec = bcd2bin(alm_tm->tm_sec);

        if (alm_en & S3C2410_RTCALM_MINEN)
                alm_tm->tm_min = bcd2bin(alm_tm->tm_min);

        if (alm_en & S3C2410_RTCALM_HOUREN)
                alm_tm->tm_hour = bcd2bin(alm_tm->tm_hour);

        if (alm_en & S3C2410_RTCALM_DAYEN)
                alm_tm->tm_mday = bcd2bin(alm_tm->tm_mday);

        if (alm_en & S3C2410_RTCALM_MONEN) {
                alm_tm->tm_mon = bcd2bin(alm_tm->tm_mon);
                alm_tm->tm_mon -= 1;
        }

        if (alm_en & S3C2410_RTCALM_YEAREN)
                alm_tm->tm_year = bcd2bin(alm_tm->tm_year);

        return 0;
}

static int s3c_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        struct s3c_rtc *info = dev_get_drvdata(dev);
        struct rtc_time *tm = &alrm->time;
        unsigned int alrm_en;
        int ret;

        dev_dbg(dev, "s3c_rtc_setalarm: %d, %ptR\n", alrm->enabled, tm);

        ret = s3c_rtc_enable_clk(info);
        if (ret)
                return ret;

        alrm_en = readb(info->base + S3C2410_RTCALM) & S3C2410_RTCALM_ALMEN;
        writeb(0x00, info->base + S3C2410_RTCALM);

        if (tm->tm_sec < 60 && tm->tm_sec >= 0) {
                alrm_en |= S3C2410_RTCALM_SECEN;
                writeb(bin2bcd(tm->tm_sec), info->base + S3C2410_ALMSEC);
        }

        if (tm->tm_min < 60 && tm->tm_min >= 0) {
                alrm_en |= S3C2410_RTCALM_MINEN;
                writeb(bin2bcd(tm->tm_min), info->base + S3C2410_ALMMIN);
        }

        if (tm->tm_hour < 24 && tm->tm_hour >= 0) {
                alrm_en |= S3C2410_RTCALM_HOUREN;
                writeb(bin2bcd(tm->tm_hour), info->base + S3C2410_ALMHOUR);
        }

        if (tm->tm_mon < 12 && tm->tm_mon >= 0) {
                alrm_en |= S3C2410_RTCALM_MONEN;
                writeb(bin2bcd(tm->tm_mon + 1), info->base + S3C2410_ALMMON);
        }

        if (tm->tm_mday <= 31 && tm->tm_mday >= 1) {
                alrm_en |= S3C2410_RTCALM_DAYEN;
                writeb(bin2bcd(tm->tm_mday), info->base + S3C2410_ALMDATE);
        }

        dev_dbg(dev, "setting S3C2410_RTCALM to %08x\n", alrm_en);

        writeb(alrm_en, info->base + S3C2410_RTCALM);

        s3c_rtc_setaie(dev, alrm->enabled);

        s3c_rtc_disable_clk(info);

        return 0;
}

static const struct rtc_class_ops s3c_rtcops = {
        .read_time      = s3c_rtc_gettime,
        .set_time       = s3c_rtc_settime,
        .read_alarm     = s3c_rtc_getalarm,
        .set_alarm      = s3c_rtc_setalarm,
        .alarm_irq_enable = s3c_rtc_setaie,
};

static void s3c6410_rtc_enable(struct s3c_rtc *info)
{
        unsigned int con, tmp;

        con = readw(info->base + S3C2410_RTCCON);
        /* re-enable the device, and check it is ok */
        if ((con & S3C2410_RTCCON_RTCEN) == 0) {
                dev_info(info->dev, "rtc disabled, re-enabling\n");

                tmp = readw(info->base + S3C2410_RTCCON);
                writew(tmp | S3C2410_RTCCON_RTCEN, info->base + S3C2410_RTCCON);
        }

        if (con & S3C2410_RTCCON_CNTSEL) {
                dev_info(info->dev, "removing RTCCON_CNTSEL\n");

                tmp = readw(info->base + S3C2410_RTCCON);
                writew(tmp & ~S3C2410_RTCCON_CNTSEL,
                       info->base + S3C2410_RTCCON);
        }

        if (con & S3C2410_RTCCON_CLKRST) {
                dev_info(info->dev, "removing RTCCON_CLKRST\n");

                tmp = readw(info->base + S3C2410_RTCCON);
                writew(tmp & ~S3C2410_RTCCON_CLKRST,
                       info->base + S3C2410_RTCCON);
        }
}

static void s3c6410_rtc_disable(struct s3c_rtc *info)
{
        unsigned int con;

        con = readw(info->base + S3C2410_RTCCON);
        con &= ~S3C64XX_RTCCON_TICEN;
        con &= ~S3C2410_RTCCON_RTCEN;
        writew(con, info->base + S3C2410_RTCCON);
}

static void s3c_rtc_remove(struct platform_device *pdev)
{
        struct s3c_rtc *info = platform_get_drvdata(pdev);

        s3c_rtc_setaie(info->dev, 0);

        if (info->data->needs_src_clk)
                clk_unprepare(info->rtc_src_clk);
        clk_unprepare(info->rtc_clk);
}

static int s3c_rtc_probe(struct platform_device *pdev)
{
        struct s3c_rtc *info = NULL;
        int ret;

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

        info->dev = &pdev->dev;
        info->data = of_device_get_match_data(&pdev->dev);
        if (!info->data) {
                dev_err(&pdev->dev, "failed getting s3c_rtc_data\n");
                return -EINVAL;
        }
        spin_lock_init(&info->alarm_lock);

        platform_set_drvdata(pdev, info);

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

        dev_dbg(&pdev->dev, "s3c2410_rtc: alarm irq %d\n", info->irq_alarm);

        /* get the memory region */
        info->base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(info->base))
                return PTR_ERR(info->base);

        info->rtc_clk = devm_clk_get(&pdev->dev, "rtc");
        if (IS_ERR(info->rtc_clk))
                return dev_err_probe(&pdev->dev, PTR_ERR(info->rtc_clk),
                                     "failed to find rtc clock\n");
        ret = clk_prepare_enable(info->rtc_clk);
        if (ret)
                return ret;

        if (info->data->needs_src_clk) {
                info->rtc_src_clk = devm_clk_get(&pdev->dev, "rtc_src");
                if (IS_ERR(info->rtc_src_clk)) {
                        ret = dev_err_probe(&pdev->dev, PTR_ERR(info->rtc_src_clk),
                                            "failed to find rtc source clock\n");
                        goto err_src_clk;
                }
                ret = clk_prepare_enable(info->rtc_src_clk);
                if (ret)
                        goto err_src_clk;
        }

        /* disable RTC enable bits potentially set by the bootloader */
        if (info->data->disable)
                info->data->disable(info);

        /* check to see if everything is setup correctly */
        if (info->data->enable)
                info->data->enable(info);

        dev_dbg(&pdev->dev, "s3c2410_rtc: RTCCON=%02x\n",
                readw(info->base + S3C2410_RTCCON));

        device_init_wakeup(&pdev->dev, true);

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

        info->rtc->ops = &s3c_rtcops;
        info->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
        info->rtc->range_max = RTC_TIMESTAMP_END_2099;

        ret = devm_rtc_register_device(info->rtc);
        if (ret)
                goto err_nortc;

        ret = devm_request_irq(&pdev->dev, info->irq_alarm, s3c_rtc_alarmirq,
                               0, "s3c2410-rtc alarm", info);
        if (ret) {
                dev_err(&pdev->dev, "IRQ%d error %d\n", info->irq_alarm, ret);
                goto err_nortc;
        }

        s3c_rtc_disable_clk(info);

        return 0;

err_nortc:
        if (info->data->disable)
                info->data->disable(info);

        if (info->data->needs_src_clk)
                clk_disable_unprepare(info->rtc_src_clk);
err_src_clk:
        clk_disable_unprepare(info->rtc_clk);

        return ret;
}

#ifdef CONFIG_PM_SLEEP

static int s3c_rtc_suspend(struct device *dev)
{
        struct s3c_rtc *info = dev_get_drvdata(dev);
        int ret;

        ret = s3c_rtc_enable_clk(info);
        if (ret)
                return ret;

        if (info->data->disable)
                info->data->disable(info);

        if (device_may_wakeup(dev) && !info->wake_en) {
                if (enable_irq_wake(info->irq_alarm) == 0)
                        info->wake_en = true;
                else
                        dev_err(dev, "enable_irq_wake failed\n");
        }

        return 0;
}

static int s3c_rtc_resume(struct device *dev)
{
        struct s3c_rtc *info = dev_get_drvdata(dev);

        if (info->data->enable)
                info->data->enable(info);

        s3c_rtc_disable_clk(info);

        if (device_may_wakeup(dev) && info->wake_en) {
                disable_irq_wake(info->irq_alarm);
                info->wake_en = false;
        }

        return 0;
}
#endif
static SIMPLE_DEV_PM_OPS(s3c_rtc_pm_ops, s3c_rtc_suspend, s3c_rtc_resume);

static void s3c6410_rtc_irq(struct s3c_rtc *info, int mask)
{
        rtc_update_irq(info->rtc, 1, RTC_AF | RTC_IRQF);
        writeb(mask, info->base + S3C2410_INTP);
}

static const struct s3c_rtc_data s3c6410_rtc_data = {
        .needs_src_clk          = true,
        .irq_handler            = s3c6410_rtc_irq,
        .enable                 = s3c6410_rtc_enable,
        .disable                = s3c6410_rtc_disable,
};

static const __maybe_unused struct of_device_id s3c_rtc_dt_match[] = {
        {
                .compatible = "samsung,s3c6410-rtc",
                .data = &s3c6410_rtc_data,
        }, {
                .compatible = "samsung,exynos3250-rtc",
                .data = &s3c6410_rtc_data,
        },
        { /* sentinel */ },
};
MODULE_DEVICE_TABLE(of, s3c_rtc_dt_match);

static struct platform_driver s3c_rtc_driver = {
        .probe          = s3c_rtc_probe,
        .remove         = s3c_rtc_remove,
        .driver         = {
                .name   = "s3c-rtc",
                .pm     = &s3c_rtc_pm_ops,
                .of_match_table = of_match_ptr(s3c_rtc_dt_match),
        },
};
module_platform_driver(s3c_rtc_driver);

MODULE_DESCRIPTION("Samsung S3C RTC Driver");
MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");
MODULE_LICENSE("GPL");