// 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");