// SPDX-License-Identifier: GPL-2.0+
/*
 * drivers/rtc/rtc-rc5t619.c
 *
 * Real time clock driver for RICOH RC5T619 power management chip.
 *
 * Copyright (C) 2019 Andreas Kemnade
 */

#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mfd/rn5t618.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/bcd.h>
#include <linux/rtc.h>
#include <linux/slab.h>
#include <linux/irqdomain.h>

struct rc5t619_rtc {
        int                     irq;
        struct rtc_device       *rtc;
        struct rn5t618 *rn5t618;
};

#define CTRL1_ALARM_ENABLED 0x40
#define CTRL1_24HR 0x20
#define CTRL1_PERIODIC_MASK 0xf

#define CTRL2_PON 0x10
#define CTRL2_ALARM_STATUS 0x80
#define CTRL2_CTFG 0x4
#define CTRL2_CTC 0x1

#define MONTH_CENTFLAG 0x80
#define HOUR_PMFLAG 0x20
#define MDAY_DAL_EXT 0x80

static uint8_t rtc5t619_12hour_bcd2bin(uint8_t hour)
{
        if (hour & HOUR_PMFLAG) {
                hour = bcd2bin(hour & ~HOUR_PMFLAG);
                return hour == 12 ? 12 : 12 + hour;
        }

        hour = bcd2bin(hour);
        return hour == 12 ? 0 : hour;
}

static uint8_t rtc5t619_12hour_bin2bcd(uint8_t hour)
{
        if (!hour)
                return 0x12;

        if (hour < 12)
                return bin2bcd(hour);

        if (hour == 12)
                return 0x12 | HOUR_PMFLAG;

        return bin2bcd(hour - 12) | HOUR_PMFLAG;
}

static int rc5t619_rtc_periodic_disable(struct device *dev)
{
        struct rc5t619_rtc *rtc = dev_get_drvdata(dev);
        int err;

        /* disable function */
        err = regmap_update_bits(rtc->rn5t618->regmap,
                                 RN5T618_RTC_CTRL1, CTRL1_PERIODIC_MASK, 0);
        if (err < 0)
                return err;

        /* clear alarm flag and CTFG */
        err = regmap_update_bits(rtc->rn5t618->regmap, RN5T618_RTC_CTRL2,
                                 CTRL2_ALARM_STATUS | CTRL2_CTFG | CTRL2_CTC,
                                 0);
        if (err < 0)
                return err;

        return 0;
}

/* things to be done once after power on */
static int rc5t619_rtc_pon_setup(struct device *dev)
{
        struct rc5t619_rtc *rtc = dev_get_drvdata(dev);
        int err;
        unsigned int reg_data;

        err = regmap_read(rtc->rn5t618->regmap, RN5T618_RTC_CTRL2, &reg_data);
        if (err < 0)
                return err;

        /* clear VDET PON */
        reg_data &= ~(CTRL2_PON | CTRL2_CTC | 0x4a);    /* 0101-1011 */
        reg_data |= 0x20;       /* 0010-0000 */
        err = regmap_write(rtc->rn5t618->regmap, RN5T618_RTC_CTRL2, reg_data);
        if (err < 0)
                return err;

        /* clearing RTC Adjust register */
        err = regmap_write(rtc->rn5t618->regmap, RN5T618_RTC_ADJUST, 0);
        if (err)
                return err;

        return regmap_update_bits(rtc->rn5t618->regmap,
                                        RN5T618_RTC_CTRL1,
                                        CTRL1_24HR, CTRL1_24HR);
}

static int rc5t619_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        struct rc5t619_rtc *rtc = dev_get_drvdata(dev);
        u8 buff[7];
        int err;
        int cent_flag;
        unsigned int ctrl1;
        unsigned int ctrl2;

        err = regmap_read(rtc->rn5t618->regmap, RN5T618_RTC_CTRL2, &ctrl2);
        if (err < 0)
                return err;

        if (ctrl2 & CTRL2_PON)
                return -EINVAL;

        err = regmap_read(rtc->rn5t618->regmap, RN5T618_RTC_CTRL1, &ctrl1);
        if (err < 0)
                return err;

        err = regmap_bulk_read(rtc->rn5t618->regmap, RN5T618_RTC_SECONDS,
                               buff, sizeof(buff));
        if (err < 0)
                return err;

        if (buff[5] & MONTH_CENTFLAG)
                cent_flag = 1;
        else
                cent_flag = 0;

        tm->tm_sec  = bcd2bin(buff[0]);
        tm->tm_min  = bcd2bin(buff[1]);

        if (ctrl1 & CTRL1_24HR)
                tm->tm_hour = bcd2bin(buff[2]);
        else
                tm->tm_hour = rtc5t619_12hour_bcd2bin(buff[2]);

        tm->tm_wday = bcd2bin(buff[3]);
        tm->tm_mday = bcd2bin(buff[4]);
        tm->tm_mon  = bcd2bin(buff[5] & 0x1f) - 1; /* back to system 0-11 */
        tm->tm_year = bcd2bin(buff[6]) + 100 * cent_flag;

        return 0;
}

static int rc5t619_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        struct rc5t619_rtc *rtc = dev_get_drvdata(dev);
        u8 buff[7];
        int err;
        int cent_flag;
        unsigned int ctrl1;
        unsigned int ctrl2;

        err = regmap_read(rtc->rn5t618->regmap, RN5T618_RTC_CTRL2, &ctrl2);
        if (err < 0)
                return err;

        if (ctrl2 & CTRL2_PON)
                rc5t619_rtc_pon_setup(dev);

        err = regmap_read(rtc->rn5t618->regmap, RN5T618_RTC_CTRL1, &ctrl1);
        if (err < 0)
                return err;

        if (tm->tm_year >= 100)
                cent_flag = 1;
        else
                cent_flag = 0;

        buff[0] = bin2bcd(tm->tm_sec);
        buff[1] = bin2bcd(tm->tm_min);

        if (ctrl1 & CTRL1_24HR)
                buff[2] = bin2bcd(tm->tm_hour);
        else
                buff[2] = rtc5t619_12hour_bin2bcd(tm->tm_hour);

        buff[3] = bin2bcd(tm->tm_wday);
        buff[4] = bin2bcd(tm->tm_mday);
        buff[5] = bin2bcd(tm->tm_mon + 1);      /* system set 0-11 */
        buff[6] = bin2bcd(tm->tm_year - cent_flag * 100);

        if (cent_flag)
                buff[5] |= MONTH_CENTFLAG;

        err = regmap_bulk_write(rtc->rn5t618->regmap, RN5T618_RTC_SECONDS,
                                buff, sizeof(buff));
        if (err < 0) {
                dev_err(dev, "failed to program new time: %d\n", err);
                return err;
        }

        return 0;
}

/* 0-disable, 1-enable */
static int rc5t619_rtc_alarm_enable(struct device *dev, unsigned int enabled)
{
        struct rc5t619_rtc *rtc = dev_get_drvdata(dev);

        return regmap_update_bits(rtc->rn5t618->regmap,
                        RN5T618_RTC_CTRL1,
                        CTRL1_ALARM_ENABLED,
                        enabled ? CTRL1_ALARM_ENABLED : 0);
}

static int rc5t619_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        struct rc5t619_rtc *rtc = dev_get_drvdata(dev);
        u8 buff[6];
        unsigned int buff_cent;
        int err;
        int cent_flag;
        unsigned int ctrl1;

        err = regmap_read(rtc->rn5t618->regmap, RN5T618_RTC_CTRL1, &ctrl1);
        if (err)
                return err;

        err = regmap_read(rtc->rn5t618->regmap, RN5T618_RTC_MONTH, &buff_cent);
        if (err < 0) {
                dev_err(dev, "failed to read time: %d\n", err);
                return err;
        }

        if (buff_cent & MONTH_CENTFLAG)
                cent_flag = 1;
        else
                cent_flag = 0;

        err = regmap_bulk_read(rtc->rn5t618->regmap, RN5T618_RTC_ALARM_Y_SEC,
                               buff, sizeof(buff));
        if (err)
                return err;

        buff[3] = buff[3] & 0x3f;

        alrm->time.tm_sec  = bcd2bin(buff[0]);
        alrm->time.tm_min  = bcd2bin(buff[1]);

        if (ctrl1 & CTRL1_24HR)
                alrm->time.tm_hour = bcd2bin(buff[2]);
        else
                alrm->time.tm_hour = rtc5t619_12hour_bcd2bin(buff[2]);

        alrm->time.tm_mday = bcd2bin(buff[3]);
        alrm->time.tm_mon  = bcd2bin(buff[4]) - 1;
        alrm->time.tm_year = bcd2bin(buff[5]) + 100 * cent_flag;
        alrm->enabled = !!(ctrl1 & CTRL1_ALARM_ENABLED);
        dev_dbg(dev, "read alarm: %ptR\n", &alrm->time);

        return 0;
}

static int rc5t619_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        struct rc5t619_rtc *rtc = dev_get_drvdata(dev);
        u8 buff[6];
        int err;
        int cent_flag;
        unsigned int ctrl1;

        err = regmap_read(rtc->rn5t618->regmap, RN5T618_RTC_CTRL1, &ctrl1);
        if (err)
                return err;

        err = rc5t619_rtc_alarm_enable(dev, 0);
        if (err < 0)
                return err;

        if (rtc->irq == -1)
                return -EINVAL;

        if (alrm->enabled == 0)
                return 0;

        if (alrm->time.tm_year >= 100)
                cent_flag = 1;
        else
                cent_flag = 0;

        alrm->time.tm_mon += 1;
        buff[0] = bin2bcd(alrm->time.tm_sec);
        buff[1] = bin2bcd(alrm->time.tm_min);

        if (ctrl1 & CTRL1_24HR)
                buff[2] = bin2bcd(alrm->time.tm_hour);
        else
                buff[2] = rtc5t619_12hour_bin2bcd(alrm->time.tm_hour);

        buff[3] = bin2bcd(alrm->time.tm_mday);
        buff[4] = bin2bcd(alrm->time.tm_mon);
        buff[5] = bin2bcd(alrm->time.tm_year - 100 * cent_flag);
        buff[3] |= MDAY_DAL_EXT;

        err = regmap_bulk_write(rtc->rn5t618->regmap, RN5T618_RTC_ALARM_Y_SEC,
                                buff, sizeof(buff));
        if (err < 0)
                return err;

        return rc5t619_rtc_alarm_enable(dev, alrm->enabled);
}

static const struct rtc_class_ops rc5t619_rtc_ops = {
        .read_time      = rc5t619_rtc_read_time,
        .set_time       = rc5t619_rtc_set_time,
        .set_alarm      = rc5t619_rtc_set_alarm,
        .read_alarm     = rc5t619_rtc_read_alarm,
        .alarm_irq_enable = rc5t619_rtc_alarm_enable,
};

static int rc5t619_rtc_alarm_flag_clr(struct device *dev)
{
        struct rc5t619_rtc *rtc = dev_get_drvdata(dev);

        /* clear alarm-D status bits.*/
        return regmap_update_bits(rtc->rn5t618->regmap,
                                RN5T618_RTC_CTRL2,
                                CTRL2_ALARM_STATUS | CTRL2_CTC, 0);
}

static irqreturn_t rc5t619_rtc_irq(int irq, void *data)
{
        struct device *dev = data;
        struct rc5t619_rtc *rtc = dev_get_drvdata(dev);

        rc5t619_rtc_alarm_flag_clr(dev);

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

static int rc5t619_rtc_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct rn5t618 *rn5t618 = dev_get_drvdata(pdev->dev.parent);
        struct rc5t619_rtc *rtc;
        unsigned int ctrl2;
        int err;

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

        rtc->rn5t618 = rn5t618;

        dev_set_drvdata(dev, rtc);
        rtc->irq = -1;

        if (rn5t618->irq_data)
                rtc->irq = regmap_irq_get_virq(rn5t618->irq_data,
                                               RN5T618_IRQ_RTC);

        if (rtc->irq  < 0)
                rtc->irq = -1;

        err = regmap_read(rtc->rn5t618->regmap, RN5T618_RTC_CTRL2, &ctrl2);
        if (err < 0)
                return err;

        /* disable rtc periodic function */
        err = rc5t619_rtc_periodic_disable(&pdev->dev);
        if (err)
                return err;

        if (ctrl2 & CTRL2_PON) {
                err = rc5t619_rtc_alarm_flag_clr(&pdev->dev);
                if (err)
                        return err;
        }

        rtc->rtc = devm_rtc_allocate_device(&pdev->dev);
        if (IS_ERR(rtc->rtc)) {
                err = PTR_ERR(rtc->rtc);
                dev_err(dev, "RTC device register: err %d\n", err);
                return err;
        }

        rtc->rtc->ops = &rc5t619_rtc_ops;
        rtc->rtc->range_min = RTC_TIMESTAMP_BEGIN_1900;
        rtc->rtc->range_max = RTC_TIMESTAMP_END_2099;

        /* set interrupt and enable it */
        if (rtc->irq != -1) {
                err = devm_request_threaded_irq(&pdev->dev, rtc->irq, NULL,
                                                rc5t619_rtc_irq,
                                                IRQF_ONESHOT,
                                                "rtc-rc5t619",
                                                &pdev->dev);
                if (err < 0) {
                        dev_err(&pdev->dev, "request IRQ:%d fail\n", rtc->irq);
                        rtc->irq = -1;

                        err = rc5t619_rtc_alarm_enable(&pdev->dev, 0);
                        if (err)
                                return err;

                } else {
                        /* enable wake */
                        device_init_wakeup(&pdev->dev, true);
                        enable_irq_wake(rtc->irq);
                }
        } else {
                /* system don't want to using alarm interrupt, so close it */
                err = rc5t619_rtc_alarm_enable(&pdev->dev, 0);
                if (err)
                        return err;

                dev_warn(&pdev->dev, "rc5t619 interrupt is disabled\n");
        }

        return devm_rtc_register_device(rtc->rtc);
}

static const struct platform_device_id rc5t619_rtc_id[] = {
        {
                .name = "rc5t619-rtc",
        }, {
                /* sentinel */
        }
};
MODULE_DEVICE_TABLE(platform, rc5t619_rtc_id);

static struct platform_driver rc5t619_rtc_driver = {
        .driver = {
                .name   = "rc5t619-rtc",
        },
        .probe  = rc5t619_rtc_probe,
        .id_table = rc5t619_rtc_id,
};
module_platform_driver(rc5t619_rtc_driver);

MODULE_DESCRIPTION("RICOH RC5T619 RTC driver");
MODULE_LICENSE("GPL");