// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * RTC driver for NXP LPC178x/18xx/43xx Real-Time Clock (RTC)
 *
 * Copyright (C) 2011 NXP Semiconductors
 * Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com>
 */

#include <linux/clk.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>

/* LPC24xx RTC register offsets and bits */
#define LPC24XX_ILR             0x00
#define  LPC24XX_RTCCIF         BIT(0)
#define  LPC24XX_RTCALF         BIT(1)
#define LPC24XX_CTC             0x04
#define LPC24XX_CCR             0x08
#define  LPC24XX_CLKEN          BIT(0)
#define  LPC178X_CCALEN         BIT(4)
#define LPC24XX_CIIR            0x0c
#define LPC24XX_AMR             0x10
#define  LPC24XX_ALARM_DISABLE  0xff
#define LPC24XX_CTIME0          0x14
#define LPC24XX_CTIME1          0x18
#define LPC24XX_CTIME2          0x1c
#define LPC24XX_SEC             0x20
#define LPC24XX_MIN             0x24
#define LPC24XX_HOUR            0x28
#define LPC24XX_DOM             0x2c
#define LPC24XX_DOW             0x30
#define LPC24XX_DOY             0x34
#define LPC24XX_MONTH           0x38
#define LPC24XX_YEAR            0x3c
#define LPC24XX_ALSEC           0x60
#define LPC24XX_ALMIN           0x64
#define LPC24XX_ALHOUR          0x68
#define LPC24XX_ALDOM           0x6c
#define LPC24XX_ALDOW           0x70
#define LPC24XX_ALDOY           0x74
#define LPC24XX_ALMON           0x78
#define LPC24XX_ALYEAR          0x7c

/* Macros to read fields in consolidated time (CT) registers */
#define CT0_SECS(x)             (((x) >> 0)  & 0x3f)
#define CT0_MINS(x)             (((x) >> 8)  & 0x3f)
#define CT0_HOURS(x)            (((x) >> 16) & 0x1f)
#define CT0_DOW(x)              (((x) >> 24) & 0x07)
#define CT1_DOM(x)              (((x) >> 0)  & 0x1f)
#define CT1_MONTH(x)            (((x) >> 8)  & 0x0f)
#define CT1_YEAR(x)             (((x) >> 16) & 0xfff)
#define CT2_DOY(x)              (((x) >> 0)  & 0xfff)

#define rtc_readl(dev, reg)             readl((dev)->rtc_base + (reg))
#define rtc_writel(dev, reg, val)       writel((val), (dev)->rtc_base + (reg))

struct lpc24xx_rtc {
        void __iomem *rtc_base;
        struct rtc_device *rtc;
        struct clk *clk_rtc;
        struct clk *clk_reg;
};

static int lpc24xx_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);

        /* Disable RTC during update */
        rtc_writel(rtc, LPC24XX_CCR, LPC178X_CCALEN);

        rtc_writel(rtc, LPC24XX_SEC,    tm->tm_sec);
        rtc_writel(rtc, LPC24XX_MIN,    tm->tm_min);
        rtc_writel(rtc, LPC24XX_HOUR,   tm->tm_hour);
        rtc_writel(rtc, LPC24XX_DOW,    tm->tm_wday);
        rtc_writel(rtc, LPC24XX_DOM,    tm->tm_mday);
        rtc_writel(rtc, LPC24XX_DOY,    tm->tm_yday);
        rtc_writel(rtc, LPC24XX_MONTH,  tm->tm_mon);
        rtc_writel(rtc, LPC24XX_YEAR,   tm->tm_year);

        rtc_writel(rtc, LPC24XX_CCR, LPC24XX_CLKEN | LPC178X_CCALEN);

        return 0;
}

static int lpc24xx_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);
        u32 ct0, ct1, ct2;

        ct0 = rtc_readl(rtc, LPC24XX_CTIME0);
        ct1 = rtc_readl(rtc, LPC24XX_CTIME1);
        ct2 = rtc_readl(rtc, LPC24XX_CTIME2);

        tm->tm_sec  = CT0_SECS(ct0);
        tm->tm_min  = CT0_MINS(ct0);
        tm->tm_hour = CT0_HOURS(ct0);
        tm->tm_wday = CT0_DOW(ct0);
        tm->tm_mon  = CT1_MONTH(ct1);
        tm->tm_mday = CT1_DOM(ct1);
        tm->tm_year = CT1_YEAR(ct1);
        tm->tm_yday = CT2_DOY(ct2);

        return 0;
}

static int lpc24xx_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
{
        struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);
        struct rtc_time *tm = &wkalrm->time;

        tm->tm_sec  = rtc_readl(rtc, LPC24XX_ALSEC);
        tm->tm_min  = rtc_readl(rtc, LPC24XX_ALMIN);
        tm->tm_hour = rtc_readl(rtc, LPC24XX_ALHOUR);
        tm->tm_mday = rtc_readl(rtc, LPC24XX_ALDOM);
        tm->tm_wday = rtc_readl(rtc, LPC24XX_ALDOW);
        tm->tm_yday = rtc_readl(rtc, LPC24XX_ALDOY);
        tm->tm_mon  = rtc_readl(rtc, LPC24XX_ALMON);
        tm->tm_year = rtc_readl(rtc, LPC24XX_ALYEAR);

        wkalrm->enabled = rtc_readl(rtc, LPC24XX_AMR) == 0;
        wkalrm->pending = !!(rtc_readl(rtc, LPC24XX_ILR) & LPC24XX_RTCCIF);

        return rtc_valid_tm(&wkalrm->time);
}

static int lpc24xx_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
{
        struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);
        struct rtc_time *tm = &wkalrm->time;

        /* Disable alarm irq during update */
        rtc_writel(rtc, LPC24XX_AMR, LPC24XX_ALARM_DISABLE);

        rtc_writel(rtc, LPC24XX_ALSEC,  tm->tm_sec);
        rtc_writel(rtc, LPC24XX_ALMIN,  tm->tm_min);
        rtc_writel(rtc, LPC24XX_ALHOUR, tm->tm_hour);
        rtc_writel(rtc, LPC24XX_ALDOM,  tm->tm_mday);
        rtc_writel(rtc, LPC24XX_ALDOW,  tm->tm_wday);
        rtc_writel(rtc, LPC24XX_ALDOY,  tm->tm_yday);
        rtc_writel(rtc, LPC24XX_ALMON,  tm->tm_mon);
        rtc_writel(rtc, LPC24XX_ALYEAR, tm->tm_year);

        if (wkalrm->enabled)
                rtc_writel(rtc, LPC24XX_AMR, 0);

        return 0;
}

static int lpc24xx_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
{
        struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);

        if (enable)
                rtc_writel(rtc, LPC24XX_AMR, 0);
        else
                rtc_writel(rtc, LPC24XX_AMR, LPC24XX_ALARM_DISABLE);

        return 0;
}

static irqreturn_t lpc24xx_rtc_interrupt(int irq, void *data)
{
        unsigned long events = RTC_IRQF;
        struct lpc24xx_rtc *rtc = data;
        u32 rtc_iir;

        /* Check interrupt cause */
        rtc_iir = rtc_readl(rtc, LPC24XX_ILR);
        if (rtc_iir & LPC24XX_RTCALF) {
                events |= RTC_AF;
                rtc_writel(rtc, LPC24XX_AMR, LPC24XX_ALARM_DISABLE);
        }

        /* Clear interrupt status and report event */
        rtc_writel(rtc, LPC24XX_ILR, rtc_iir);
        rtc_update_irq(rtc->rtc, 1, events);

        return IRQ_HANDLED;
}

static const struct rtc_class_ops lpc24xx_rtc_ops = {
        .read_time              = lpc24xx_rtc_read_time,
        .set_time               = lpc24xx_rtc_set_time,
        .read_alarm             = lpc24xx_rtc_read_alarm,
        .set_alarm              = lpc24xx_rtc_set_alarm,
        .alarm_irq_enable       = lpc24xx_rtc_alarm_irq_enable,
};

static int lpc24xx_rtc_probe(struct platform_device *pdev)
{
        struct lpc24xx_rtc *rtc;
        int irq, ret;

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

        rtc->rtc_base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(rtc->rtc_base))
                return PTR_ERR(rtc->rtc_base);

        irq = platform_get_irq(pdev, 0);
        if (irq < 0)
                return irq;

        rtc->clk_rtc = devm_clk_get(&pdev->dev, "rtc");
        if (IS_ERR(rtc->clk_rtc)) {
                dev_err(&pdev->dev, "error getting rtc clock\n");
                return PTR_ERR(rtc->clk_rtc);
        }

        rtc->clk_reg = devm_clk_get(&pdev->dev, "reg");
        if (IS_ERR(rtc->clk_reg)) {
                dev_err(&pdev->dev, "error getting reg clock\n");
                return PTR_ERR(rtc->clk_reg);
        }

        ret = clk_prepare_enable(rtc->clk_rtc);
        if (ret) {
                dev_err(&pdev->dev, "unable to enable rtc clock\n");
                return ret;
        }

        ret = clk_prepare_enable(rtc->clk_reg);
        if (ret) {
                dev_err(&pdev->dev, "unable to enable reg clock\n");
                goto disable_rtc_clk;
        }

        platform_set_drvdata(pdev, rtc);

        /* Clear any pending interrupts */
        rtc_writel(rtc, LPC24XX_ILR, LPC24XX_RTCCIF | LPC24XX_RTCALF);

        /* Enable RTC count */
        rtc_writel(rtc, LPC24XX_CCR, LPC24XX_CLKEN | LPC178X_CCALEN);

        ret = devm_request_irq(&pdev->dev, irq, lpc24xx_rtc_interrupt, 0,
                               pdev->name, rtc);
        if (ret < 0) {
                dev_warn(&pdev->dev, "can't request interrupt\n");
                goto disable_clks;
        }

        rtc->rtc = devm_rtc_device_register(&pdev->dev, "lpc24xx-rtc",
                                            &lpc24xx_rtc_ops, THIS_MODULE);
        if (IS_ERR(rtc->rtc)) {
                dev_err(&pdev->dev, "can't register rtc device\n");
                ret = PTR_ERR(rtc->rtc);
                goto disable_clks;
        }

        return 0;

disable_clks:
        clk_disable_unprepare(rtc->clk_reg);
disable_rtc_clk:
        clk_disable_unprepare(rtc->clk_rtc);
        return ret;
}

static void lpc24xx_rtc_remove(struct platform_device *pdev)
{
        struct lpc24xx_rtc *rtc = platform_get_drvdata(pdev);

        /* Ensure all interrupt sources are masked */
        rtc_writel(rtc, LPC24XX_AMR, LPC24XX_ALARM_DISABLE);
        rtc_writel(rtc, LPC24XX_CIIR, 0);

        rtc_writel(rtc, LPC24XX_CCR, LPC178X_CCALEN);

        clk_disable_unprepare(rtc->clk_rtc);
        clk_disable_unprepare(rtc->clk_reg);
}

static const struct of_device_id lpc24xx_rtc_match[] = {
        { .compatible = "nxp,lpc1788-rtc" },
        { }
};
MODULE_DEVICE_TABLE(of, lpc24xx_rtc_match);

static struct platform_driver lpc24xx_rtc_driver = {
        .probe  = lpc24xx_rtc_probe,
        .remove = lpc24xx_rtc_remove,
        .driver = {
                .name = "lpc24xx-rtc",
                .of_match_table = lpc24xx_rtc_match,
        },
};
module_platform_driver(lpc24xx_rtc_driver);

MODULE_AUTHOR("Kevin Wells <wellsk40@gmail.com>");
MODULE_DESCRIPTION("RTC driver for the LPC178x/18xx/408x/43xx SoCs");
MODULE_LICENSE("GPL");