// SPDX-License-Identifier: GPL-2.0+
//
// RTC driver for Maxim MAX8998
//
// Copyright (C) 2010 Samsung Electronics Co.Ltd
// Author: Minkyu Kang <mk7.kang@samsung.com>
// Author: Joonyoung Shim <jy0922.shim@samsung.com>

#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/slab.h>
#include <linux/bcd.h>
#include <linux/irqdomain.h>
#include <linux/rtc.h>
#include <linux/platform_device.h>
#include <linux/mfd/max8998.h>
#include <linux/mfd/max8998-private.h>
#include <linux/delay.h>

#define MAX8998_RTC_SEC                 0x00
#define MAX8998_RTC_MIN                 0x01
#define MAX8998_RTC_HOUR                0x02
#define MAX8998_RTC_WEEKDAY             0x03
#define MAX8998_RTC_DATE                0x04
#define MAX8998_RTC_MONTH               0x05
#define MAX8998_RTC_YEAR1               0x06
#define MAX8998_RTC_YEAR2               0x07
#define MAX8998_ALARM0_SEC              0x08
#define MAX8998_ALARM0_MIN              0x09
#define MAX8998_ALARM0_HOUR             0x0a
#define MAX8998_ALARM0_WEEKDAY          0x0b
#define MAX8998_ALARM0_DATE             0x0c
#define MAX8998_ALARM0_MONTH            0x0d
#define MAX8998_ALARM0_YEAR1            0x0e
#define MAX8998_ALARM0_YEAR2            0x0f
#define MAX8998_ALARM1_SEC              0x10
#define MAX8998_ALARM1_MIN              0x11
#define MAX8998_ALARM1_HOUR             0x12
#define MAX8998_ALARM1_WEEKDAY          0x13
#define MAX8998_ALARM1_DATE             0x14
#define MAX8998_ALARM1_MONTH            0x15
#define MAX8998_ALARM1_YEAR1            0x16
#define MAX8998_ALARM1_YEAR2            0x17
#define MAX8998_ALARM0_CONF             0x18
#define MAX8998_ALARM1_CONF             0x19
#define MAX8998_RTC_STATUS              0x1a
#define MAX8998_WTSR_SMPL_CNTL          0x1b
#define MAX8998_TEST                    0x1f

#define HOUR_12                         (1 << 7)
#define HOUR_PM                         (1 << 5)
#define ALARM0_STATUS                   (1 << 1)
#define ALARM1_STATUS                   (1 << 2)

enum {
        RTC_SEC = 0,
        RTC_MIN,
        RTC_HOUR,
        RTC_WEEKDAY,
        RTC_DATE,
        RTC_MONTH,
        RTC_YEAR1,
        RTC_YEAR2,
};

struct max8998_rtc_info {
        struct device           *dev;
        struct max8998_dev      *max8998;
        struct i2c_client       *rtc;
        struct rtc_device       *rtc_dev;
        int irq;
        bool lp3974_bug_workaround;
};

static void max8998_data_to_tm(u8 *data, struct rtc_time *tm)
{
        tm->tm_sec = bcd2bin(data[RTC_SEC]);
        tm->tm_min = bcd2bin(data[RTC_MIN]);
        if (data[RTC_HOUR] & HOUR_12) {
                tm->tm_hour = bcd2bin(data[RTC_HOUR] & 0x1f);
                if (data[RTC_HOUR] & HOUR_PM)
                        tm->tm_hour += 12;
        } else
                tm->tm_hour = bcd2bin(data[RTC_HOUR] & 0x3f);

        tm->tm_wday = data[RTC_WEEKDAY] & 0x07;
        tm->tm_mday = bcd2bin(data[RTC_DATE]);
        tm->tm_mon = bcd2bin(data[RTC_MONTH]);
        tm->tm_year = bcd2bin(data[RTC_YEAR1]) + bcd2bin(data[RTC_YEAR2]) * 100;
        tm->tm_year -= 1900;
}

static void max8998_tm_to_data(struct rtc_time *tm, u8 *data)
{
        data[RTC_SEC] = bin2bcd(tm->tm_sec);
        data[RTC_MIN] = bin2bcd(tm->tm_min);
        data[RTC_HOUR] = bin2bcd(tm->tm_hour);
        data[RTC_WEEKDAY] = tm->tm_wday;
        data[RTC_DATE] = bin2bcd(tm->tm_mday);
        data[RTC_MONTH] = bin2bcd(tm->tm_mon);
        data[RTC_YEAR1] = bin2bcd(tm->tm_year % 100);
        data[RTC_YEAR2] = bin2bcd((tm->tm_year + 1900) / 100);
}

static int max8998_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        struct max8998_rtc_info *info = dev_get_drvdata(dev);
        u8 data[8];
        int ret;

        ret = max8998_bulk_read(info->rtc, MAX8998_RTC_SEC, 8, data);
        if (ret < 0)
                return ret;

        max8998_data_to_tm(data, tm);

        return 0;
}

static int max8998_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        struct max8998_rtc_info *info = dev_get_drvdata(dev);
        u8 data[8];
        int ret;

        max8998_tm_to_data(tm, data);

        ret = max8998_bulk_write(info->rtc, MAX8998_RTC_SEC, 8, data);

        if (info->lp3974_bug_workaround)
                msleep(2000);

        return ret;
}

static int max8998_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        struct max8998_rtc_info *info = dev_get_drvdata(dev);
        u8 data[8];
        u8 val;
        int ret;

        ret = max8998_bulk_read(info->rtc, MAX8998_ALARM0_SEC, 8, data);
        if (ret < 0)
                return ret;

        max8998_data_to_tm(data, &alrm->time);

        ret = max8998_read_reg(info->rtc, MAX8998_ALARM0_CONF, &val);
        if (ret < 0)
                return ret;

        alrm->enabled = !!val;

        ret = max8998_read_reg(info->rtc, MAX8998_RTC_STATUS, &val);
        if (ret < 0)
                return ret;

        if (val & ALARM0_STATUS)
                alrm->pending = 1;
        else
                alrm->pending = 0;

        return 0;
}

static int max8998_rtc_stop_alarm(struct max8998_rtc_info *info)
{
        int ret = max8998_write_reg(info->rtc, MAX8998_ALARM0_CONF, 0);

        if (info->lp3974_bug_workaround)
                msleep(2000);

        return ret;
}

static int max8998_rtc_start_alarm(struct max8998_rtc_info *info)
{
        int ret;
        u8 alarm0_conf = 0x77;

        /* LP3974 with delay bug chips has rtc alarm bugs with "MONTH" field */
        if (info->lp3974_bug_workaround)
                alarm0_conf = 0x57;

        ret = max8998_write_reg(info->rtc, MAX8998_ALARM0_CONF, alarm0_conf);

        if (info->lp3974_bug_workaround)
                msleep(2000);

        return ret;
}

static int max8998_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
        struct max8998_rtc_info *info = dev_get_drvdata(dev);
        u8 data[8];
        int ret;

        max8998_tm_to_data(&alrm->time, data);

        ret = max8998_rtc_stop_alarm(info);
        if (ret < 0)
                return ret;

        ret = max8998_bulk_write(info->rtc, MAX8998_ALARM0_SEC, 8, data);
        if (ret < 0)
                return ret;

        if (info->lp3974_bug_workaround)
                msleep(2000);

        if (alrm->enabled)
                ret = max8998_rtc_start_alarm(info);

        return ret;
}

static int max8998_rtc_alarm_irq_enable(struct device *dev,
                                        unsigned int enabled)
{
        struct max8998_rtc_info *info = dev_get_drvdata(dev);

        if (enabled)
                return max8998_rtc_start_alarm(info);
        else
                return max8998_rtc_stop_alarm(info);
}

static irqreturn_t max8998_rtc_alarm_irq(int irq, void *data)
{
        struct max8998_rtc_info *info = data;

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

        return IRQ_HANDLED;
}

static const struct rtc_class_ops max8998_rtc_ops = {
        .read_time = max8998_rtc_read_time,
        .set_time = max8998_rtc_set_time,
        .read_alarm = max8998_rtc_read_alarm,
        .set_alarm = max8998_rtc_set_alarm,
        .alarm_irq_enable = max8998_rtc_alarm_irq_enable,
};

static int max8998_rtc_probe(struct platform_device *pdev)
{
        struct max8998_dev *max8998 = dev_get_drvdata(pdev->dev.parent);
        struct max8998_platform_data *pdata = max8998->pdata;
        struct max8998_rtc_info *info;
        int ret;

        info = devm_kzalloc(&pdev->dev, sizeof(struct max8998_rtc_info),
                        GFP_KERNEL);
        if (!info)
                return -ENOMEM;

        info->dev = &pdev->dev;
        info->max8998 = max8998;
        info->rtc = max8998->rtc;

        platform_set_drvdata(pdev, info);

        info->rtc_dev = devm_rtc_device_register(&pdev->dev, "max8998-rtc",
                        &max8998_rtc_ops, THIS_MODULE);

        if (IS_ERR(info->rtc_dev)) {
                ret = PTR_ERR(info->rtc_dev);
                dev_err(&pdev->dev, "Failed to register RTC device: %d\n", ret);
                return ret;
        }

        if (!max8998->irq_domain)
                goto no_irq;

        info->irq = irq_create_mapping(max8998->irq_domain, MAX8998_IRQ_ALARM0);
        if (!info->irq) {
                dev_warn(&pdev->dev, "Failed to map alarm IRQ\n");
                goto no_irq;
        }

        ret = devm_request_threaded_irq(&pdev->dev, info->irq, NULL,
                                max8998_rtc_alarm_irq, 0, "rtc-alarm0", info);

        if (ret < 0)
                dev_err(&pdev->dev, "Failed to request alarm IRQ: %d: %d\n",
                        info->irq, ret);

no_irq:
        dev_info(&pdev->dev, "RTC CHIP NAME: %s\n", pdev->id_entry->name);
        if (pdata && pdata->rtc_delay) {
                info->lp3974_bug_workaround = true;
                dev_warn(&pdev->dev, "LP3974 with RTC REGERR option."
                                " RTC updates will be extremely slow.\n");
        }

        return 0;
}

static const struct platform_device_id max8998_rtc_id[] = {
        { "max8998-rtc", TYPE_MAX8998 },
        { "lp3974-rtc", TYPE_LP3974 },
        { }
};
MODULE_DEVICE_TABLE(platform, max8998_rtc_id);

static struct platform_driver max8998_rtc_driver = {
        .driver         = {
                .name   = "max8998-rtc",
        },
        .probe          = max8998_rtc_probe,
        .id_table       = max8998_rtc_id,
};

module_platform_driver(max8998_rtc_driver);

MODULE_AUTHOR("Minkyu Kang <mk7.kang@samsung.com>");
MODULE_AUTHOR("Joonyoung Shim <jy0922.shim@samsung.com>");
MODULE_DESCRIPTION("Maxim MAX8998 RTC driver");
MODULE_LICENSE("GPL");