// SPDX-License-Identifier: GPL-2.0-only
/*
 * rtc-cv1800.c: RTC driver for Sophgo cv1800 RTC
 *
 * Author: Jingbao Qiu <qiujingbao.dlmu@gmail.com>
 */

#include <linux/clk.h>
#include <linux/irq.h>
#include <linux/kernel.h>
#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/rtc.h>

#define SEC_PULSE_GEN          0x1004
#define ALARM_TIME             0x1008
#define ALARM_ENABLE           0x100C
#define SET_SEC_CNTR_VAL       0x1010
#define SET_SEC_CNTR_TRIG      0x1014
#define SEC_CNTR_VAL           0x1018

/*
 * When in VDDBKUP domain, this MACRO register
 * does not power down
 */
#define MACRO_RO_T             0x14A8
#define MACRO_RG_SET_T         0x1498

#define ALARM_ENABLE_MASK      BIT(0)
#define SEL_SEC_PULSE          BIT(31)

struct cv1800_rtc_priv {
        struct rtc_device *rtc_dev;
        struct regmap *rtc_map;
        struct clk *clk;
        int irq;
};

static bool cv1800_rtc_enabled(struct device *dev)
{
        struct cv1800_rtc_priv *info = dev_get_drvdata(dev);
        u32 reg;

        regmap_read(info->rtc_map, SEC_PULSE_GEN, &reg);

        return (reg & SEL_SEC_PULSE) == 0;
}

static void cv1800_rtc_enable(struct device *dev)
{
        struct cv1800_rtc_priv *info = dev_get_drvdata(dev);

        /* Sec pulse generated internally */
        regmap_update_bits(info->rtc_map, SEC_PULSE_GEN, SEL_SEC_PULSE, 0);
}

static int cv1800_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
        struct cv1800_rtc_priv *info = dev_get_drvdata(dev);

        regmap_write(info->rtc_map, ALARM_ENABLE, enabled);

        return 0;
}

static int cv1800_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        struct cv1800_rtc_priv *info = dev_get_drvdata(dev);
        unsigned long alarm_time;

        alarm_time = rtc_tm_to_time64(&alrm->time);

        cv1800_rtc_alarm_irq_enable(dev, 0);

        regmap_write(info->rtc_map, ALARM_TIME, alarm_time);

        cv1800_rtc_alarm_irq_enable(dev, alrm->enabled);

        return 0;
}

static int cv1800_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
        struct cv1800_rtc_priv *info = dev_get_drvdata(dev);
        u32 enabled;
        u32 time;

        if (!cv1800_rtc_enabled(dev)) {
                alarm->enabled = 0;
                return 0;
        }

        regmap_read(info->rtc_map, ALARM_ENABLE, &enabled);

        alarm->enabled = enabled & ALARM_ENABLE_MASK;

        regmap_read(info->rtc_map, ALARM_TIME, &time);

        rtc_time64_to_tm(time, &alarm->time);

        return 0;
}

static int cv1800_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        struct cv1800_rtc_priv *info = dev_get_drvdata(dev);
        u32 sec;

        if (!cv1800_rtc_enabled(dev))
                return -EINVAL;

        regmap_read(info->rtc_map, SEC_CNTR_VAL, &sec);

        rtc_time64_to_tm(sec, tm);

        return 0;
}

static int cv1800_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        struct cv1800_rtc_priv *info = dev_get_drvdata(dev);
        unsigned long sec;

        sec = rtc_tm_to_time64(tm);

        regmap_write(info->rtc_map, SET_SEC_CNTR_VAL, sec);
        regmap_write(info->rtc_map, SET_SEC_CNTR_TRIG, 1);

        regmap_write(info->rtc_map, MACRO_RG_SET_T, sec);

        cv1800_rtc_enable(dev);

        return 0;
}

static irqreturn_t cv1800_rtc_irq_handler(int irq, void *dev_id)
{
        struct cv1800_rtc_priv *info = dev_id;

        rtc_update_irq(info->rtc_dev, 1, RTC_IRQF | RTC_AF);

        regmap_write(info->rtc_map, ALARM_ENABLE, 0);

        return IRQ_HANDLED;
}

static const struct rtc_class_ops cv1800_rtc_ops = {
        .read_time = cv1800_rtc_read_time,
        .set_time = cv1800_rtc_set_time,
        .read_alarm = cv1800_rtc_read_alarm,
        .set_alarm = cv1800_rtc_set_alarm,
        .alarm_irq_enable = cv1800_rtc_alarm_irq_enable,
};

static int cv1800_rtc_probe(struct platform_device *pdev)
{
        struct cv1800_rtc_priv *rtc;
        int ret;

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

        rtc->rtc_map = device_node_to_regmap(pdev->dev.parent->of_node);
        if (IS_ERR(rtc->rtc_map))
                return dev_err_probe(&pdev->dev, PTR_ERR(rtc->rtc_map),
                                     "cannot get parent regmap\n");

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

        rtc->clk = devm_clk_get_enabled(pdev->dev.parent, "rtc");
        if (IS_ERR(rtc->clk))
                return dev_err_probe(&pdev->dev, PTR_ERR(rtc->clk),
                                     "rtc clk not found\n");

        platform_set_drvdata(pdev, rtc);

        device_init_wakeup(&pdev->dev, 1);

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

        rtc->rtc_dev->ops = &cv1800_rtc_ops;
        rtc->rtc_dev->range_max = U32_MAX;

        ret = devm_request_irq(&pdev->dev, rtc->irq, cv1800_rtc_irq_handler,
                               IRQF_TRIGGER_HIGH, "rtc alarm", rtc);
        if (ret)
                return dev_err_probe(&pdev->dev, ret,
                                     "cannot register interrupt handler\n");

        return devm_rtc_register_device(rtc->rtc_dev);
}

static const struct platform_device_id cv1800_rtc_id[] = {
        { .name = "cv1800b-rtc" },
        { /* sentinel */ },
};
MODULE_DEVICE_TABLE(platform, cv1800_rtc_id);

static struct platform_driver cv1800_rtc_driver = {
        .driver = {
                .name = "sophgo-cv1800-rtc",
        },
        .probe = cv1800_rtc_probe,
        .id_table = cv1800_rtc_id,
};

module_platform_driver(cv1800_rtc_driver);
MODULE_AUTHOR("Jingbao Qiu");
MODULE_DESCRIPTION("Sophgo cv1800 RTC Driver");
MODULE_LICENSE("GPL");