// SPDX-License-Identifier: GPL-2.0+
//
// Copyright 2004-2008 Freescale Semiconductor, Inc. All Rights Reserved.

#include <linux/io.h>
#include <linux/rtc.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/pm_wakeirq.h>
#include <linux/clk.h>
#include <linux/of.h>

#define RTC_INPUT_CLK_32768HZ   (0x00 << 5)
#define RTC_INPUT_CLK_32000HZ   (0x01 << 5)
#define RTC_INPUT_CLK_38400HZ   (0x02 << 5)

#define RTC_SW_BIT      (1 << 0)
#define RTC_ALM_BIT     (1 << 2)
#define RTC_1HZ_BIT     (1 << 4)
#define RTC_2HZ_BIT     (1 << 7)
#define RTC_SAM0_BIT    (1 << 8)
#define RTC_SAM1_BIT    (1 << 9)
#define RTC_SAM2_BIT    (1 << 10)
#define RTC_SAM3_BIT    (1 << 11)
#define RTC_SAM4_BIT    (1 << 12)
#define RTC_SAM5_BIT    (1 << 13)
#define RTC_SAM6_BIT    (1 << 14)
#define RTC_SAM7_BIT    (1 << 15)
#define PIT_ALL_ON      (RTC_2HZ_BIT | RTC_SAM0_BIT | RTC_SAM1_BIT | \
                         RTC_SAM2_BIT | RTC_SAM3_BIT | RTC_SAM4_BIT | \
                         RTC_SAM5_BIT | RTC_SAM6_BIT | RTC_SAM7_BIT)

#define RTC_ENABLE_BIT  (1 << 7)

#define MAX_PIE_NUM     9
#define MAX_PIE_FREQ    512

#define MXC_RTC_TIME    0
#define MXC_RTC_ALARM   1

#define RTC_HOURMIN     0x00    /*  32bit rtc hour/min counter reg */
#define RTC_SECOND      0x04    /*  32bit rtc seconds counter reg */
#define RTC_ALRM_HM     0x08    /*  32bit rtc alarm hour/min reg */
#define RTC_ALRM_SEC    0x0C    /*  32bit rtc alarm seconds reg */
#define RTC_RTCCTL      0x10    /*  32bit rtc control reg */
#define RTC_RTCISR      0x14    /*  32bit rtc interrupt status reg */
#define RTC_RTCIENR     0x18    /*  32bit rtc interrupt enable reg */
#define RTC_STPWCH      0x1C    /*  32bit rtc stopwatch min reg */
#define RTC_DAYR        0x20    /*  32bit rtc days counter reg */
#define RTC_DAYALARM    0x24    /*  32bit rtc day alarm reg */
#define RTC_TEST1       0x28    /*  32bit rtc test reg 1 */
#define RTC_TEST2       0x2C    /*  32bit rtc test reg 2 */
#define RTC_TEST3       0x30    /*  32bit rtc test reg 3 */

enum imx_rtc_type {
        IMX1_RTC,
        IMX21_RTC,
};

struct rtc_plat_data {
        struct rtc_device *rtc;
        void __iomem *ioaddr;
        int irq;
        struct clk *clk_ref;
        struct clk *clk_ipg;
        struct rtc_time g_rtc_alarm;
        enum imx_rtc_type devtype;
};

static const struct of_device_id imx_rtc_dt_ids[] = {
        { .compatible = "fsl,imx1-rtc", .data = (const void *)IMX1_RTC },
        { .compatible = "fsl,imx21-rtc", .data = (const void *)IMX21_RTC },
        {}
};
MODULE_DEVICE_TABLE(of, imx_rtc_dt_ids);

static inline int is_imx1_rtc(struct rtc_plat_data *data)
{
        return data->devtype == IMX1_RTC;
}

/*
 * This function is used to obtain the RTC time or the alarm value in
 * second.
 */
static time64_t get_alarm_or_time(struct device *dev, int time_alarm)
{
        struct rtc_plat_data *pdata = dev_get_drvdata(dev);
        void __iomem *ioaddr = pdata->ioaddr;
        u32 day = 0, hr = 0, min = 0, sec = 0, hr_min = 0;

        switch (time_alarm) {
        case MXC_RTC_TIME:
                day = readw(ioaddr + RTC_DAYR);
                hr_min = readw(ioaddr + RTC_HOURMIN);
                sec = readw(ioaddr + RTC_SECOND);
                break;
        case MXC_RTC_ALARM:
                day = readw(ioaddr + RTC_DAYALARM);
                hr_min = readw(ioaddr + RTC_ALRM_HM) & 0xffff;
                sec = readw(ioaddr + RTC_ALRM_SEC);
                break;
        }

        hr = hr_min >> 8;
        min = hr_min & 0xff;

        return ((((time64_t)day * 24 + hr) * 60) + min) * 60 + sec;
}

/*
 * This function sets the RTC alarm value or the time value.
 */
static void set_alarm_or_time(struct device *dev, int time_alarm, time64_t time)
{
        u32 tod, day, hr, min, sec, temp;
        struct rtc_plat_data *pdata = dev_get_drvdata(dev);
        void __iomem *ioaddr = pdata->ioaddr;

        day = div_s64_rem(time, 86400, &tod);

        /* time is within a day now */
        hr = tod / 3600;
        tod -= hr * 3600;

        /* time is within an hour now */
        min = tod / 60;
        sec = tod - min * 60;

        temp = (hr << 8) + min;

        switch (time_alarm) {
        case MXC_RTC_TIME:
                writew(day, ioaddr + RTC_DAYR);
                writew(sec, ioaddr + RTC_SECOND);
                writew(temp, ioaddr + RTC_HOURMIN);
                break;
        case MXC_RTC_ALARM:
                writew(day, ioaddr + RTC_DAYALARM);
                writew(sec, ioaddr + RTC_ALRM_SEC);
                writew(temp, ioaddr + RTC_ALRM_HM);
                break;
        }
}

/*
 * This function updates the RTC alarm registers and then clears all the
 * interrupt status bits.
 */
static void rtc_update_alarm(struct device *dev, struct rtc_time *alrm)
{
        time64_t time;
        struct rtc_plat_data *pdata = dev_get_drvdata(dev);
        void __iomem *ioaddr = pdata->ioaddr;

        time = rtc_tm_to_time64(alrm);

        /* clear all the interrupt status bits */
        writew(readw(ioaddr + RTC_RTCISR), ioaddr + RTC_RTCISR);
        set_alarm_or_time(dev, MXC_RTC_ALARM, time);
}

static void mxc_rtc_irq_enable(struct device *dev, unsigned int bit,
                                unsigned int enabled)
{
        struct rtc_plat_data *pdata = dev_get_drvdata(dev);
        void __iomem *ioaddr = pdata->ioaddr;
        u32 reg;
        unsigned long flags;

        spin_lock_irqsave(&pdata->rtc->irq_lock, flags);
        reg = readw(ioaddr + RTC_RTCIENR);

        if (enabled)
                reg |= bit;
        else
                reg &= ~bit;

        writew(reg, ioaddr + RTC_RTCIENR);
        spin_unlock_irqrestore(&pdata->rtc->irq_lock, flags);
}

/* This function is the RTC interrupt service routine. */
static irqreturn_t mxc_rtc_interrupt(int irq, void *dev_id)
{
        struct platform_device *pdev = dev_id;
        struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
        void __iomem *ioaddr = pdata->ioaddr;
        u32 status;
        u32 events = 0;

        spin_lock(&pdata->rtc->irq_lock);
        status = readw(ioaddr + RTC_RTCISR) & readw(ioaddr + RTC_RTCIENR);
        /* clear interrupt sources */
        writew(status, ioaddr + RTC_RTCISR);

        /* update irq data & counter */
        if (status & RTC_ALM_BIT) {
                events |= (RTC_AF | RTC_IRQF);
                /* RTC alarm should be one-shot */
                mxc_rtc_irq_enable(&pdev->dev, RTC_ALM_BIT, 0);
        }

        if (status & PIT_ALL_ON)
                events |= (RTC_PF | RTC_IRQF);

        rtc_update_irq(pdata->rtc, 1, events);
        spin_unlock(&pdata->rtc->irq_lock);

        return IRQ_HANDLED;
}

static int mxc_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
        mxc_rtc_irq_enable(dev, RTC_ALM_BIT, enabled);
        return 0;
}

/*
 * This function reads the current RTC time into tm in Gregorian date.
 */
static int mxc_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        time64_t val;

        /* Avoid roll-over from reading the different registers */
        do {
                val = get_alarm_or_time(dev, MXC_RTC_TIME);
        } while (val != get_alarm_or_time(dev, MXC_RTC_TIME));

        rtc_time64_to_tm(val, tm);

        return 0;
}

/*
 * This function sets the internal RTC time based on tm in Gregorian date.
 */
static int mxc_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        time64_t time = rtc_tm_to_time64(tm);

        /* Avoid roll-over from reading the different registers */
        do {
                set_alarm_or_time(dev, MXC_RTC_TIME, time);
        } while (time != get_alarm_or_time(dev, MXC_RTC_TIME));

        return 0;
}

/*
 * This function reads the current alarm value into the passed in 'alrm'
 * argument. It updates the alrm's pending field value based on the whether
 * an alarm interrupt occurs or not.
 */
static int mxc_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        struct rtc_plat_data *pdata = dev_get_drvdata(dev);
        void __iomem *ioaddr = pdata->ioaddr;

        rtc_time64_to_tm(get_alarm_or_time(dev, MXC_RTC_ALARM), &alrm->time);
        alrm->pending = ((readw(ioaddr + RTC_RTCISR) & RTC_ALM_BIT)) ? 1 : 0;

        return 0;
}

/*
 * This function sets the RTC alarm based on passed in alrm.
 */
static int mxc_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        struct rtc_plat_data *pdata = dev_get_drvdata(dev);

        rtc_update_alarm(dev, &alrm->time);

        memcpy(&pdata->g_rtc_alarm, &alrm->time, sizeof(struct rtc_time));
        mxc_rtc_irq_enable(dev, RTC_ALM_BIT, alrm->enabled);

        return 0;
}

/* RTC layer */
static const struct rtc_class_ops mxc_rtc_ops = {
        .read_time              = mxc_rtc_read_time,
        .set_time               = mxc_rtc_set_time,
        .read_alarm             = mxc_rtc_read_alarm,
        .set_alarm              = mxc_rtc_set_alarm,
        .alarm_irq_enable       = mxc_rtc_alarm_irq_enable,
};

static int mxc_rtc_probe(struct platform_device *pdev)
{
        struct rtc_device *rtc;
        struct rtc_plat_data *pdata = NULL;
        u32 reg;
        unsigned long rate;
        int ret;

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

        pdata->devtype = (uintptr_t)of_device_get_match_data(&pdev->dev);

        pdata->ioaddr = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(pdata->ioaddr))
                return PTR_ERR(pdata->ioaddr);

        rtc = devm_rtc_allocate_device(&pdev->dev);
        if (IS_ERR(rtc))
                return PTR_ERR(rtc);

        pdata->rtc = rtc;
        rtc->ops = &mxc_rtc_ops;
        if (is_imx1_rtc(pdata)) {
                struct rtc_time tm;

                /* 9bit days + hours minutes seconds */
                rtc->range_max = (1 << 9) * 86400 - 1;

                /*
                 * Set the start date as beginning of the current year. This can
                 * be overridden using device tree.
                 */
                rtc_time64_to_tm(ktime_get_real_seconds(), &tm);
                rtc->start_secs =  mktime64(tm.tm_year, 1, 1, 0, 0, 0);
                rtc->set_start_time = true;
        } else {
                /* 16bit days + hours minutes seconds */
                rtc->range_max = (1 << 16) * 86400ULL - 1;
        }

        pdata->clk_ipg = devm_clk_get_enabled(&pdev->dev, "ipg");
        if (IS_ERR(pdata->clk_ipg)) {
                dev_err(&pdev->dev, "unable to get ipg clock!\n");
                return PTR_ERR(pdata->clk_ipg);
        }

        pdata->clk_ref = devm_clk_get_enabled(&pdev->dev, "ref");
        if (IS_ERR(pdata->clk_ref)) {
                dev_err(&pdev->dev, "unable to get ref clock!\n");
                return PTR_ERR(pdata->clk_ref);
        }

        rate = clk_get_rate(pdata->clk_ref);

        if (rate == 32768)
                reg = RTC_INPUT_CLK_32768HZ;
        else if (rate == 32000)
                reg = RTC_INPUT_CLK_32000HZ;
        else if (rate == 38400)
                reg = RTC_INPUT_CLK_38400HZ;
        else {
                dev_err(&pdev->dev, "rtc clock is not valid (%lu)\n", rate);
                return -EINVAL;
        }

        reg |= RTC_ENABLE_BIT;
        writew(reg, (pdata->ioaddr + RTC_RTCCTL));
        if (((readw(pdata->ioaddr + RTC_RTCCTL)) & RTC_ENABLE_BIT) == 0) {
                dev_err(&pdev->dev, "hardware module can't be enabled!\n");
                return -EIO;
        }

        platform_set_drvdata(pdev, pdata);

        /* Configure and enable the RTC */
        pdata->irq = platform_get_irq(pdev, 0);

        if (pdata->irq >= 0 &&
            devm_request_irq(&pdev->dev, pdata->irq, mxc_rtc_interrupt,
                             IRQF_SHARED, pdev->name, pdev) < 0) {
                dev_warn(&pdev->dev, "interrupt not available.\n");
                pdata->irq = -1;
        }

        if (pdata->irq >= 0) {
                device_init_wakeup(&pdev->dev, true);
                ret = dev_pm_set_wake_irq(&pdev->dev, pdata->irq);
                if (ret)
                        dev_err(&pdev->dev, "failed to enable irq wake\n");
        }

        ret = devm_rtc_register_device(rtc);

        return ret;
}

static struct platform_driver mxc_rtc_driver = {
        .driver = {
                   .name        = "mxc_rtc",
                   .of_match_table = imx_rtc_dt_ids,
        },
        .probe = mxc_rtc_probe,
};

module_platform_driver(mxc_rtc_driver)

MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>");
MODULE_DESCRIPTION("RTC driver for Freescale MXC");
MODULE_LICENSE("GPL");