// SPDX-License-Identifier: GPL-2.0-only
/*
 * TI LP8788 MFD - rtc driver
 *
 * Copyright 2012 Texas Instruments
 *
 * Author: Milo(Woogyom) Kim <milo.kim@ti.com>
 */

#include <linux/err.h>
#include <linux/irqdomain.h>
#include <linux/mfd/lp8788.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/slab.h>

/* register address */
#define LP8788_INTEN_3                  0x05
#define LP8788_RTC_UNLOCK               0x64
#define LP8788_RTC_SEC                  0x70
#define LP8788_ALM1_SEC                 0x77
#define LP8788_ALM1_EN                  0x7D
#define LP8788_ALM2_SEC                 0x7E
#define LP8788_ALM2_EN                  0x84

/* mask/shift bits */
#define LP8788_INT_RTC_ALM1_M           BIT(1)  /* Addr 05h */
#define LP8788_INT_RTC_ALM1_S           1
#define LP8788_INT_RTC_ALM2_M           BIT(2)  /* Addr 05h */
#define LP8788_INT_RTC_ALM2_S           2
#define LP8788_ALM_EN_M                 BIT(7)  /* Addr 7Dh or 84h */
#define LP8788_ALM_EN_S                 7

#define DEFAULT_ALARM_SEL               LP8788_ALARM_1
#define LP8788_MONTH_OFFSET             1
#define LP8788_BASE_YEAR                2000
#define MAX_WDAY_BITS                   7
#define LP8788_WDAY_SET                 1
#define RTC_UNLOCK                      0x1
#define RTC_LATCH                       0x2
#define ALARM_IRQ_FLAG                  (RTC_IRQF | RTC_AF)

enum lp8788_time {
        LPTIME_SEC,
        LPTIME_MIN,
        LPTIME_HOUR,
        LPTIME_MDAY,
        LPTIME_MON,
        LPTIME_YEAR,
        LPTIME_WDAY,
        LPTIME_MAX,
};

struct lp8788_rtc {
        struct lp8788 *lp;
        struct rtc_device *rdev;
        enum lp8788_alarm_sel alarm;
        int irq;
};

static const u8 addr_alarm_sec[LP8788_ALARM_MAX] = {
        LP8788_ALM1_SEC,
        LP8788_ALM2_SEC,
};

static const u8 addr_alarm_en[LP8788_ALARM_MAX] = {
        LP8788_ALM1_EN,
        LP8788_ALM2_EN,
};

static const u8 mask_alarm_en[LP8788_ALARM_MAX] = {
        LP8788_INT_RTC_ALM1_M,
        LP8788_INT_RTC_ALM2_M,
};

static const u8 shift_alarm_en[LP8788_ALARM_MAX] = {
        LP8788_INT_RTC_ALM1_S,
        LP8788_INT_RTC_ALM2_S,
};

static int _to_tm_wday(u8 lp8788_wday)
{
        int i;

        if (lp8788_wday == 0)
                return 0;

        /* lookup defined weekday from read register value */
        for (i = 0; i < MAX_WDAY_BITS; i++) {
                if ((lp8788_wday >> i) == LP8788_WDAY_SET)
                        break;
        }

        return i + 1;
}

static inline int _to_lp8788_wday(int tm_wday)
{
        return LP8788_WDAY_SET << (tm_wday - 1);
}

static void lp8788_rtc_unlock(struct lp8788 *lp)
{
        lp8788_write_byte(lp, LP8788_RTC_UNLOCK, RTC_UNLOCK);
        lp8788_write_byte(lp, LP8788_RTC_UNLOCK, RTC_LATCH);
}

static int lp8788_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        struct lp8788_rtc *rtc = dev_get_drvdata(dev);
        struct lp8788 *lp = rtc->lp;
        u8 data[LPTIME_MAX];
        int ret;

        lp8788_rtc_unlock(lp);

        ret = lp8788_read_multi_bytes(lp, LP8788_RTC_SEC, data, LPTIME_MAX);
        if (ret)
                return ret;

        tm->tm_sec  = data[LPTIME_SEC];
        tm->tm_min  = data[LPTIME_MIN];
        tm->tm_hour = data[LPTIME_HOUR];
        tm->tm_mday = data[LPTIME_MDAY];
        tm->tm_mon  = data[LPTIME_MON] - LP8788_MONTH_OFFSET;
        tm->tm_year = data[LPTIME_YEAR] + LP8788_BASE_YEAR - 1900;
        tm->tm_wday = _to_tm_wday(data[LPTIME_WDAY]);

        return 0;
}

static int lp8788_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        struct lp8788_rtc *rtc = dev_get_drvdata(dev);
        struct lp8788 *lp = rtc->lp;
        u8 data[LPTIME_MAX - 1];
        int ret, i, year;

        year = tm->tm_year + 1900 - LP8788_BASE_YEAR;
        if (year < 0) {
                dev_err(lp->dev, "invalid year: %d\n", year);
                return -EINVAL;
        }

        /* because rtc weekday is a readonly register, do not update */
        data[LPTIME_SEC]  = tm->tm_sec;
        data[LPTIME_MIN]  = tm->tm_min;
        data[LPTIME_HOUR] = tm->tm_hour;
        data[LPTIME_MDAY] = tm->tm_mday;
        data[LPTIME_MON]  = tm->tm_mon + LP8788_MONTH_OFFSET;
        data[LPTIME_YEAR] = year;

        for (i = 0; i < ARRAY_SIZE(data); i++) {
                ret = lp8788_write_byte(lp, LP8788_RTC_SEC + i, data[i]);
                if (ret)
                        return ret;
        }

        return 0;
}

static int lp8788_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
        struct lp8788_rtc *rtc = dev_get_drvdata(dev);
        struct lp8788 *lp = rtc->lp;
        struct rtc_time *tm = &alarm->time;
        u8 addr, data[LPTIME_MAX];
        int ret;

        addr = addr_alarm_sec[rtc->alarm];
        ret = lp8788_read_multi_bytes(lp, addr, data, LPTIME_MAX);
        if (ret)
                return ret;

        tm->tm_sec  = data[LPTIME_SEC];
        tm->tm_min  = data[LPTIME_MIN];
        tm->tm_hour = data[LPTIME_HOUR];
        tm->tm_mday = data[LPTIME_MDAY];
        tm->tm_mon  = data[LPTIME_MON] - LP8788_MONTH_OFFSET;
        tm->tm_year = data[LPTIME_YEAR] + LP8788_BASE_YEAR - 1900;
        tm->tm_wday = _to_tm_wday(data[LPTIME_WDAY]);
        alarm->enabled = data[LPTIME_WDAY] & LP8788_ALM_EN_M;

        return 0;
}

static int lp8788_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
        struct lp8788_rtc *rtc = dev_get_drvdata(dev);
        struct lp8788 *lp = rtc->lp;
        struct rtc_time *tm = &alarm->time;
        u8 addr, data[LPTIME_MAX];
        int ret, i, year;

        year = tm->tm_year + 1900 - LP8788_BASE_YEAR;
        if (year < 0) {
                dev_err(lp->dev, "invalid year: %d\n", year);
                return -EINVAL;
        }

        data[LPTIME_SEC]  = tm->tm_sec;
        data[LPTIME_MIN]  = tm->tm_min;
        data[LPTIME_HOUR] = tm->tm_hour;
        data[LPTIME_MDAY] = tm->tm_mday;
        data[LPTIME_MON]  = tm->tm_mon + LP8788_MONTH_OFFSET;
        data[LPTIME_YEAR] = year;
        data[LPTIME_WDAY] = _to_lp8788_wday(tm->tm_wday);

        for (i = 0; i < ARRAY_SIZE(data); i++) {
                addr = addr_alarm_sec[rtc->alarm] + i;
                ret = lp8788_write_byte(lp, addr, data[i]);
                if (ret)
                        return ret;
        }

        alarm->enabled = 1;
        addr = addr_alarm_en[rtc->alarm];

        return lp8788_update_bits(lp, addr, LP8788_ALM_EN_M,
                                alarm->enabled << LP8788_ALM_EN_S);
}

static int lp8788_alarm_irq_enable(struct device *dev, unsigned int enable)
{
        struct lp8788_rtc *rtc = dev_get_drvdata(dev);
        struct lp8788 *lp = rtc->lp;
        u8 mask, shift;

        if (!rtc->irq)
                return -EIO;

        mask = mask_alarm_en[rtc->alarm];
        shift = shift_alarm_en[rtc->alarm];

        return lp8788_update_bits(lp, LP8788_INTEN_3, mask, enable << shift);
}

static const struct rtc_class_ops lp8788_rtc_ops = {
        .read_time = lp8788_rtc_read_time,
        .set_time = lp8788_rtc_set_time,
        .read_alarm = lp8788_read_alarm,
        .set_alarm = lp8788_set_alarm,
        .alarm_irq_enable = lp8788_alarm_irq_enable,
};

static irqreturn_t lp8788_alarm_irq_handler(int irq, void *ptr)
{
        struct lp8788_rtc *rtc = ptr;

        rtc_update_irq(rtc->rdev, 1, ALARM_IRQ_FLAG);
        return IRQ_HANDLED;
}

static int lp8788_alarm_irq_register(struct platform_device *pdev,
                                struct lp8788_rtc *rtc)
{
        struct resource *r;
        struct lp8788 *lp = rtc->lp;
        struct irq_domain *irqdm = lp->irqdm;
        int irq;

        rtc->irq = 0;

        /* even the alarm IRQ number is not specified, rtc time should work */
        r = platform_get_resource_byname(pdev, IORESOURCE_IRQ, LP8788_ALM_IRQ);
        if (!r)
                return 0;

        if (rtc->alarm == LP8788_ALARM_1)
                irq = r->start;
        else
                irq = r->end;

        rtc->irq = irq_create_mapping(irqdm, irq);

        return devm_request_threaded_irq(&pdev->dev, rtc->irq, NULL,
                                lp8788_alarm_irq_handler,
                                0, LP8788_ALM_IRQ, rtc);
}

static int lp8788_rtc_probe(struct platform_device *pdev)
{
        struct lp8788 *lp = dev_get_drvdata(pdev->dev.parent);
        struct lp8788_rtc *rtc;
        struct device *dev = &pdev->dev;

        rtc = devm_kzalloc(dev, sizeof(struct lp8788_rtc), GFP_KERNEL);
        if (!rtc)
                return -ENOMEM;

        rtc->lp = lp;
        rtc->alarm = lp->pdata ? lp->pdata->alarm_sel : DEFAULT_ALARM_SEL;
        platform_set_drvdata(pdev, rtc);

        device_init_wakeup(dev, true);

        rtc->rdev = devm_rtc_device_register(dev, "lp8788_rtc",
                                        &lp8788_rtc_ops, THIS_MODULE);
        if (IS_ERR(rtc->rdev)) {
                dev_err(dev, "can not register rtc device\n");
                return PTR_ERR(rtc->rdev);
        }

        if (lp8788_alarm_irq_register(pdev, rtc))
                dev_warn(lp->dev, "no rtc irq handler\n");

        return 0;
}

static struct platform_driver lp8788_rtc_driver = {
        .probe = lp8788_rtc_probe,
        .driver = {
                .name = LP8788_DEV_RTC,
        },
};
module_platform_driver(lp8788_rtc_driver);

MODULE_DESCRIPTION("Texas Instruments LP8788 RTC Driver");
MODULE_AUTHOR("Milo Kim");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:lp8788-rtc");