/*
 * RTC driver for Rockchip RK808
 *
 * Copyright (c) 2014, Fuzhou Rockchip Electronics Co., Ltd
 *
 * Author: Chris Zhong <zyw@rock-chips.com>
 * Author: Zhang Qing <zhangqing@rock-chips.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/rtc.h>
#include <linux/bcd.h>
#include <linux/mfd/rk808.h>
#include <linux/platform_device.h>
#include <linux/i2c.h>

/* RTC_CTRL_REG bitfields */
#define BIT_RTC_CTRL_REG_STOP_RTC_M		BIT(0)

/* RK808 has a shadowed register for saving a "frozen" RTC time.
 * When user setting "GET_TIME" to 1, the time will save in this shadowed
 * register. If set "READSEL" to 1, user read rtc time register, actually
 * get the time of that moment. If we need the real time, clr this bit.
 */
#define BIT_RTC_CTRL_REG_RTC_GET_TIME		BIT(6)
#define BIT_RTC_CTRL_REG_RTC_READSEL_M		BIT(7)
#define BIT_RTC_INTERRUPTS_REG_IT_ALARM_M	BIT(3)
#define RTC_STATUS_MASK		0xFE

#define SECONDS_REG_MSK		0x7F
#define MINUTES_REG_MAK		0x7F
#define HOURS_REG_MSK		0x3F
#define DAYS_REG_MSK		0x3F
#define MONTHS_REG_MSK		0x1F
#define YEARS_REG_MSK		0xFF
#define WEEKS_REG_MSK		0x7

/* REG_SECONDS_REG through REG_YEARS_REG is how many registers? */

#define NUM_TIME_REGS	(RK808_WEEKS_REG - RK808_SECONDS_REG + 1)
#define NUM_ALARM_REGS	(RK808_ALARM_YEARS_REG - RK808_ALARM_SECONDS_REG + 1)

struct rk808_rtc {
	struct rk808 *rk808;
	struct rtc_device *rtc;
	int irq;
};

/*
 * The Rockchip calendar used by the RK808 counts November with 31 days. We use
 * these translation functions to convert its dates to/from the Gregorian
 * calendar used by the rest of the world. We arbitrarily define Jan 1st, 2016
 * as the day when both calendars were in sync, and treat all other dates
 * relative to that.
 * NOTE: Other system software (e.g. firmware) that reads the same hardware must
 * implement this exact same conversion algorithm, with the same anchor date.
 */
static time64_t nov2dec_transitions(struct rtc_time *tm)
{
	return (tm->tm_year + 1900) - 2016 + (tm->tm_mon + 1 > 11 ? 1 : 0);
}

static void rockchip_to_gregorian(struct rtc_time *tm)
{
	/* If it's Nov 31st, rtc_tm_to_time64() will count that like Dec 1st */
	time64_t time = rtc_tm_to_time64(tm);
	rtc_time64_to_tm(time + nov2dec_transitions(tm) * 86400, tm);
}

static void gregorian_to_rockchip(struct rtc_time *tm)
{
	time64_t extra_days = nov2dec_transitions(tm);
	time64_t time = rtc_tm_to_time64(tm);
	rtc_time64_to_tm(time - extra_days * 86400, tm);

	/* Compensate if we went back over Nov 31st (will work up to 2381) */
	if (nov2dec_transitions(tm) < extra_days) {
		if (tm->tm_mon + 1 == 11)
			tm->tm_mday++;	/* This may result in 31! */
		else
			rtc_time64_to_tm(time - (extra_days - 1) * 86400, tm);
	}
}

/* Read current time and date in RTC */
static int rk808_rtc_readtime(struct device *dev, struct rtc_time *tm)
{
	struct rk808_rtc *rk808_rtc = dev_get_drvdata(dev);
	struct rk808 *rk808 = rk808_rtc->rk808;
	u8 rtc_data[NUM_TIME_REGS];
	int ret;

	/* Force an update of the shadowed registers right now */
	ret = regmap_update_bits(rk808->regmap, RK808_RTC_CTRL_REG,
				 BIT_RTC_CTRL_REG_RTC_GET_TIME,
				 BIT_RTC_CTRL_REG_RTC_GET_TIME);
	if (ret) {
		dev_err(dev, "Failed to update bits rtc_ctrl: %d\n", ret);
		return ret;
	}

	/*
	 * After we set the GET_TIME bit, the rtc time can't be read
	 * immediately. So we should wait up to 31.25 us, about one cycle of
	 * 32khz. If we clear the GET_TIME bit here, the time of i2c transfer
	 * certainly more than 31.25us: 16 * 2.5us at 400kHz bus frequency.
	 */
	ret = regmap_update_bits(rk808->regmap, RK808_RTC_CTRL_REG,
				 BIT_RTC_CTRL_REG_RTC_GET_TIME,
				 0);
	if (ret) {
		dev_err(dev, "Failed to update bits rtc_ctrl: %d\n", ret);
		return ret;
	}

	ret = regmap_bulk_read(rk808->regmap, RK808_SECONDS_REG,
			       rtc_data, NUM_TIME_REGS);
	if (ret) {
		dev_err(dev, "Failed to bulk read rtc_data: %d\n", ret);
		return ret;
	}

	tm->tm_sec = bcd2bin(rtc_data[0] & SECONDS_REG_MSK);
	tm->tm_min = bcd2bin(rtc_data[1] & MINUTES_REG_MAK);
	tm->tm_hour = bcd2bin(rtc_data[2] & HOURS_REG_MSK);
	tm->tm_mday = bcd2bin(rtc_data[3] & DAYS_REG_MSK);
	tm->tm_mon = (bcd2bin(rtc_data[4] & MONTHS_REG_MSK)) - 1;
	tm->tm_year = (bcd2bin(rtc_data[5] & YEARS_REG_MSK)) + 100;
	tm->tm_wday = bcd2bin(rtc_data[6] & WEEKS_REG_MSK);
	rockchip_to_gregorian(tm);
	dev_dbg(dev, "RTC date/time %4d-%02d-%02d(%d) %02d:%02d:%02d\n",
		1900 + tm->tm_year, tm->tm_mon + 1, tm->tm_mday,
		tm->tm_wday, tm->tm_hour, tm->tm_min, tm->tm_sec);

	return ret;
}

/* Set current time and date in RTC */
static int rk808_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
	struct rk808_rtc *rk808_rtc = dev_get_drvdata(dev);
	struct rk808 *rk808 = rk808_rtc->rk808;
	u8 rtc_data[NUM_TIME_REGS];
	int ret;

	dev_dbg(dev, "set RTC date/time %4d-%02d-%02d(%d) %02d:%02d:%02d\n",
		1900 + tm->tm_year, tm->tm_mon + 1, tm->tm_mday,
		tm->tm_wday, tm->tm_hour, tm->tm_min, tm->tm_sec);
	gregorian_to_rockchip(tm);
	rtc_data[0] = bin2bcd(tm->tm_sec);
	rtc_data[1] = bin2bcd(tm->tm_min);
	rtc_data[2] = bin2bcd(tm->tm_hour);
	rtc_data[3] = bin2bcd(tm->tm_mday);
	rtc_data[4] = bin2bcd(tm->tm_mon + 1);
	rtc_data[5] = bin2bcd(tm->tm_year - 100);
	rtc_data[6] = bin2bcd(tm->tm_wday);

	/* Stop RTC while updating the RTC registers */
	ret = regmap_update_bits(rk808->regmap, RK808_RTC_CTRL_REG,
				 BIT_RTC_CTRL_REG_STOP_RTC_M,
				 BIT_RTC_CTRL_REG_STOP_RTC_M);
	if (ret) {
		dev_err(dev, "Failed to update RTC control: %d\n", ret);
		return ret;
	}

	ret = regmap_bulk_write(rk808->regmap, RK808_SECONDS_REG,
				rtc_data, NUM_TIME_REGS);
	if (ret) {
		dev_err(dev, "Failed to bull write rtc_data: %d\n", ret);
		return ret;
	}
	/* Start RTC again */
	ret = regmap_update_bits(rk808->regmap, RK808_RTC_CTRL_REG,
				 BIT_RTC_CTRL_REG_STOP_RTC_M, 0);
	if (ret) {
		dev_err(dev, "Failed to update RTC control: %d\n", ret);
		return ret;
	}
	return 0;
}

/* Read alarm time and date in RTC */
static int rk808_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	struct rk808_rtc *rk808_rtc = dev_get_drvdata(dev);
	struct rk808 *rk808 = rk808_rtc->rk808;
	u8 alrm_data[NUM_ALARM_REGS];
	uint32_t int_reg;
	int ret;

	ret = regmap_bulk_read(rk808->regmap, RK808_ALARM_SECONDS_REG,
			       alrm_data, NUM_ALARM_REGS);

	alrm->time.tm_sec = bcd2bin(alrm_data[0] & SECONDS_REG_MSK);
	alrm->time.tm_min = bcd2bin(alrm_data[1] & MINUTES_REG_MAK);
	alrm->time.tm_hour = bcd2bin(alrm_data[2] & HOURS_REG_MSK);
	alrm->time.tm_mday = bcd2bin(alrm_data[3] & DAYS_REG_MSK);
	alrm->time.tm_mon = (bcd2bin(alrm_data[4] & MONTHS_REG_MSK)) - 1;
	alrm->time.tm_year = (bcd2bin(alrm_data[5] & YEARS_REG_MSK)) + 100;
	rockchip_to_gregorian(&alrm->time);

	ret = regmap_read(rk808->regmap, RK808_RTC_INT_REG, &int_reg);
	if (ret) {
		dev_err(dev, "Failed to read RTC INT REG: %d\n", ret);
		return ret;
	}

	dev_dbg(dev, "alrm read RTC date/time %4d-%02d-%02d(%d) %02d:%02d:%02d\n",
		1900 + alrm->time.tm_year, alrm->time.tm_mon + 1,
		alrm->time.tm_mday, alrm->time.tm_wday, alrm->time.tm_hour,
		alrm->time.tm_min, alrm->time.tm_sec);

	alrm->enabled = (int_reg & BIT_RTC_INTERRUPTS_REG_IT_ALARM_M) ? 1 : 0;

	return 0;
}

static int rk808_rtc_stop_alarm(struct rk808_rtc *rk808_rtc)
{
	struct rk808 *rk808 = rk808_rtc->rk808;
	int ret;

	ret = regmap_update_bits(rk808->regmap, RK808_RTC_INT_REG,
				 BIT_RTC_INTERRUPTS_REG_IT_ALARM_M, 0);

	return ret;
}

static int rk808_rtc_start_alarm(struct rk808_rtc *rk808_rtc)
{
	struct rk808 *rk808 = rk808_rtc->rk808;
	int ret;

	ret = regmap_update_bits(rk808->regmap, RK808_RTC_INT_REG,
				 BIT_RTC_INTERRUPTS_REG_IT_ALARM_M,
				 BIT_RTC_INTERRUPTS_REG_IT_ALARM_M);

	return ret;
}

static int rk808_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	struct rk808_rtc *rk808_rtc = dev_get_drvdata(dev);
	struct rk808 *rk808 = rk808_rtc->rk808;
	u8 alrm_data[NUM_ALARM_REGS];
	int ret;

	ret = rk808_rtc_stop_alarm(rk808_rtc);
	if (ret) {
		dev_err(dev, "Failed to stop alarm: %d\n", ret);
		return ret;
	}
	dev_dbg(dev, "alrm set RTC date/time %4d-%02d-%02d(%d) %02d:%02d:%02d\n",
		1900 + alrm->time.tm_year, alrm->time.tm_mon + 1,
		alrm->time.tm_mday, alrm->time.tm_wday, alrm->time.tm_hour,
		alrm->time.tm_min, alrm->time.tm_sec);

	gregorian_to_rockchip(&alrm->time);
	alrm_data[0] = bin2bcd(alrm->time.tm_sec);
	alrm_data[1] = bin2bcd(alrm->time.tm_min);
	alrm_data[2] = bin2bcd(alrm->time.tm_hour);
	alrm_data[3] = bin2bcd(alrm->time.tm_mday);
	alrm_data[4] = bin2bcd(alrm->time.tm_mon + 1);
	alrm_data[5] = bin2bcd(alrm->time.tm_year - 100);

	ret = regmap_bulk_write(rk808->regmap, RK808_ALARM_SECONDS_REG,
				alrm_data, NUM_ALARM_REGS);
	if (ret) {
		dev_err(dev, "Failed to bulk write: %d\n", ret);
		return ret;
	}
	if (alrm->enabled) {
		ret = rk808_rtc_start_alarm(rk808_rtc);
		if (ret) {
			dev_err(dev, "Failed to start alarm: %d\n", ret);
			return ret;
		}
	}
	return 0;
}

static int rk808_rtc_alarm_irq_enable(struct device *dev,
				      unsigned int enabled)
{
	struct rk808_rtc *rk808_rtc = dev_get_drvdata(dev);

	if (enabled)
		return rk808_rtc_start_alarm(rk808_rtc);

	return rk808_rtc_stop_alarm(rk808_rtc);
}

/*
 * We will just handle setting the frequency and make use the framework for
 * reading the periodic interupts.
 *
 * @freq: Current periodic IRQ freq:
 * bit 0: every second
 * bit 1: every minute
 * bit 2: every hour
 * bit 3: every day
 */
static irqreturn_t rk808_alarm_irq(int irq, void *data)
{
	struct rk808_rtc *rk808_rtc = data;
	struct rk808 *rk808 = rk808_rtc->rk808;
	struct i2c_client *client = rk808->i2c;
	int ret;

	ret = regmap_write(rk808->regmap, RK808_RTC_STATUS_REG,
			   RTC_STATUS_MASK);
	if (ret) {
		dev_err(&client->dev,
			"%s:Failed to update RTC status: %d\n", __func__, ret);
		return ret;
	}

	rtc_update_irq(rk808_rtc->rtc, 1, RTC_IRQF | RTC_AF);
	dev_dbg(&client->dev,
		 "%s:irq=%d\n", __func__, irq);
	return IRQ_HANDLED;
}

static const struct rtc_class_ops rk808_rtc_ops = {
	.read_time = rk808_rtc_readtime,
	.set_time = rk808_rtc_set_time,
	.read_alarm = rk808_rtc_readalarm,
	.set_alarm = rk808_rtc_setalarm,
	.alarm_irq_enable = rk808_rtc_alarm_irq_enable,
};

#ifdef CONFIG_PM_SLEEP
/* Turn off the alarm if it should not be a wake source. */
static int rk808_rtc_suspend(struct device *dev)
{
	struct platform_device *pdev = to_platform_device(dev);
	struct rk808_rtc *rk808_rtc = dev_get_drvdata(&pdev->dev);

	if (device_may_wakeup(dev))
		enable_irq_wake(rk808_rtc->irq);

	return 0;
}

/* Enable the alarm if it should be enabled (in case it was disabled to
 * prevent use as a wake source).
 */
static int rk808_rtc_resume(struct device *dev)
{
	struct platform_device *pdev = to_platform_device(dev);
	struct rk808_rtc *rk808_rtc = dev_get_drvdata(&pdev->dev);

	if (device_may_wakeup(dev))
		disable_irq_wake(rk808_rtc->irq);

	return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(rk808_rtc_pm_ops,
	rk808_rtc_suspend, rk808_rtc_resume);

static int rk808_rtc_probe(struct platform_device *pdev)
{
	struct rk808 *rk808 = dev_get_drvdata(pdev->dev.parent);
	struct rk808_rtc *rk808_rtc;
	struct rtc_time tm;
	int ret;

	rk808_rtc = devm_kzalloc(&pdev->dev, sizeof(*rk808_rtc), GFP_KERNEL);
	if (rk808_rtc == NULL)
		return -ENOMEM;

	platform_set_drvdata(pdev, rk808_rtc);
	rk808_rtc->rk808 = rk808;

	/* start rtc running by default, and use shadowed timer. */
	ret = regmap_update_bits(rk808->regmap, RK808_RTC_CTRL_REG,
				 BIT_RTC_CTRL_REG_STOP_RTC_M |
				 BIT_RTC_CTRL_REG_RTC_READSEL_M,
				 BIT_RTC_CTRL_REG_RTC_READSEL_M);
	if (ret) {
		dev_err(&pdev->dev,
			"Failed to update RTC control: %d\n", ret);
		return ret;
	}

	ret = regmap_write(rk808->regmap, RK808_RTC_STATUS_REG,
			   RTC_STATUS_MASK);
	if (ret) {
		dev_err(&pdev->dev,
			"Failed to write RTC status: %d\n", ret);
			return ret;
	}

	/* set init time */
	ret = rk808_rtc_readtime(&pdev->dev, &tm);
	if (ret) {
		dev_err(&pdev->dev, "Failed to read RTC time\n");
		return ret;
	}
	ret = rtc_valid_tm(&tm);
	if (ret)
		dev_warn(&pdev->dev, "invalid date/time\n");

	device_init_wakeup(&pdev->dev, 1);

	rk808_rtc->rtc = devm_rtc_device_register(&pdev->dev, "rk808-rtc",
						  &rk808_rtc_ops, THIS_MODULE);
	if (IS_ERR(rk808_rtc->rtc)) {
		ret = PTR_ERR(rk808_rtc->rtc);
		return ret;
	}

	rk808_rtc->irq = platform_get_irq(pdev, 0);
	if (rk808_rtc->irq < 0) {
		if (rk808_rtc->irq != -EPROBE_DEFER)
			dev_err(&pdev->dev, "Wake up is not possible as irq = %d\n",
				rk808_rtc->irq);
		return rk808_rtc->irq;
	}

	/* request alarm irq of rk808 */
	ret = devm_request_threaded_irq(&pdev->dev, rk808_rtc->irq, NULL,
					rk808_alarm_irq, 0,
					"RTC alarm", rk808_rtc);
	if (ret) {
		dev_err(&pdev->dev, "Failed to request alarm IRQ %d: %d\n",
			rk808_rtc->irq, ret);
	}

	return ret;
}

static struct platform_driver rk808_rtc_driver = {
	.probe = rk808_rtc_probe,
	.driver = {
		.name = "rk808-rtc",
		.pm = &rk808_rtc_pm_ops,
	},
};

module_platform_driver(rk808_rtc_driver);

MODULE_DESCRIPTION("RTC driver for the rk808 series PMICs");
MODULE_AUTHOR("Chris Zhong <zyw@rock-chips.com>");
MODULE_AUTHOR("Zhang Qing <zhangqing@rock-chips.com>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:rk808-rtc");