/*
 * rtc-tps80031.c -- TI TPS80031/TPS80032 RTC driver
 *
 * RTC driver for TI TPS80031/TPS80032 Fully Integrated
 * Power Management with Power Path and Battery Charger
 *
 * Copyright (c) 2012, NVIDIA Corporation.
 *
 * Author: Laxman Dewangan <ldewangan@nvidia.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation version 2.
 *
 * This program is distributed "as is" WITHOUT ANY WARRANTY of any kind,
 * whether express or implied; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
 * 02111-1307, USA
 */

#include <linux/bcd.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mfd/tps80031.h>
#include <linux/platform_device.h>
#include <linux/pm.h>
#include <linux/rtc.h>
#include <linux/slab.h>

#define ENABLE_ALARM_INT			0x08
#define ALARM_INT_STATUS			0x40

/**
 * Setting bit to 1 in STOP_RTC will run the RTC and
 * setting this bit to 0 will freeze RTC.
 */
#define STOP_RTC				0x1

/* Power on reset Values of RTC registers */
#define TPS80031_RTC_POR_YEAR			0
#define TPS80031_RTC_POR_MONTH			1
#define TPS80031_RTC_POR_DAY			1

/* Numbers of registers for time and alarms */
#define TPS80031_RTC_TIME_NUM_REGS		7
#define TPS80031_RTC_ALARM_NUM_REGS		6

/**
 * PMU RTC have only 2 nibbles to store year information, so using an
 * offset of 100 to set the base year as 2000 for our driver.
 */
#define RTC_YEAR_OFFSET 100

struct tps80031_rtc {
	struct rtc_device	*rtc;
	int			irq;
};

static int tps80031_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
	u8 buff[TPS80031_RTC_TIME_NUM_REGS];
	int ret;

	ret = tps80031_reads(dev->parent, TPS80031_SLAVE_ID1,
			TPS80031_SECONDS_REG, TPS80031_RTC_TIME_NUM_REGS, buff);
	if (ret < 0) {
		dev_err(dev, "reading RTC_SECONDS_REG failed, err = %d\n", ret);
		return ret;
	}

	tm->tm_sec = bcd2bin(buff[0]);
	tm->tm_min = bcd2bin(buff[1]);
	tm->tm_hour = bcd2bin(buff[2]);
	tm->tm_mday = bcd2bin(buff[3]);
	tm->tm_mon = bcd2bin(buff[4]) - 1;
	tm->tm_year = bcd2bin(buff[5]) + RTC_YEAR_OFFSET;
	tm->tm_wday = bcd2bin(buff[6]);
	return 0;
}

static int tps80031_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
	u8 buff[7];
	int ret;

	buff[0] = bin2bcd(tm->tm_sec);
	buff[1] = bin2bcd(tm->tm_min);
	buff[2] = bin2bcd(tm->tm_hour);
	buff[3] = bin2bcd(tm->tm_mday);
	buff[4] = bin2bcd(tm->tm_mon + 1);
	buff[5] = bin2bcd(tm->tm_year % RTC_YEAR_OFFSET);
	buff[6] = bin2bcd(tm->tm_wday);

	/* Stop RTC while updating the RTC time registers */
	ret = tps80031_clr_bits(dev->parent, TPS80031_SLAVE_ID1,
				TPS80031_RTC_CTRL_REG, STOP_RTC);
	if (ret < 0) {
		dev_err(dev->parent, "Stop RTC failed, err = %d\n", ret);
		return ret;
	}

	ret = tps80031_writes(dev->parent, TPS80031_SLAVE_ID1,
			TPS80031_SECONDS_REG,
			TPS80031_RTC_TIME_NUM_REGS, buff);
	if (ret < 0) {
		dev_err(dev, "writing RTC_SECONDS_REG failed, err %d\n", ret);
		return ret;
	}

	ret = tps80031_set_bits(dev->parent, TPS80031_SLAVE_ID1,
				TPS80031_RTC_CTRL_REG, STOP_RTC);
	if (ret < 0)
		dev_err(dev->parent, "Start RTC failed, err = %d\n", ret);
	return ret;
}

static int tps80031_rtc_alarm_irq_enable(struct device *dev,
					 unsigned int enable)
{
	int ret;

	if (enable)
		ret = tps80031_set_bits(dev->parent, TPS80031_SLAVE_ID1,
				TPS80031_RTC_INTERRUPTS_REG, ENABLE_ALARM_INT);
	else
		ret = tps80031_clr_bits(dev->parent, TPS80031_SLAVE_ID1,
				TPS80031_RTC_INTERRUPTS_REG, ENABLE_ALARM_INT);
	if (ret < 0) {
		dev_err(dev, "Update on RTC_INT failed, err = %d\n", ret);
		return ret;
	}
	return 0;
}

static int tps80031_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	u8 buff[TPS80031_RTC_ALARM_NUM_REGS];
	int ret;

	buff[0] = bin2bcd(alrm->time.tm_sec);
	buff[1] = bin2bcd(alrm->time.tm_min);
	buff[2] = bin2bcd(alrm->time.tm_hour);
	buff[3] = bin2bcd(alrm->time.tm_mday);
	buff[4] = bin2bcd(alrm->time.tm_mon + 1);
	buff[5] = bin2bcd(alrm->time.tm_year % RTC_YEAR_OFFSET);
	ret = tps80031_writes(dev->parent, TPS80031_SLAVE_ID1,
			TPS80031_ALARM_SECONDS_REG,
			TPS80031_RTC_ALARM_NUM_REGS, buff);
	if (ret < 0) {
		dev_err(dev, "Writing RTC_ALARM failed, err %d\n", ret);
		return ret;
	}
	return tps80031_rtc_alarm_irq_enable(dev, alrm->enabled);
}

static int tps80031_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	u8 buff[6];
	int ret;

	ret = tps80031_reads(dev->parent, TPS80031_SLAVE_ID1,
			TPS80031_ALARM_SECONDS_REG,
			TPS80031_RTC_ALARM_NUM_REGS, buff);
	if (ret < 0) {
		dev_err(dev->parent,
			"reading RTC_ALARM failed, err = %d\n", ret);
		return ret;
	}

	alrm->time.tm_sec = bcd2bin(buff[0]);
	alrm->time.tm_min = bcd2bin(buff[1]);
	alrm->time.tm_hour = bcd2bin(buff[2]);
	alrm->time.tm_mday = bcd2bin(buff[3]);
	alrm->time.tm_mon = bcd2bin(buff[4]) - 1;
	alrm->time.tm_year = bcd2bin(buff[5]) + RTC_YEAR_OFFSET;
	return 0;
}

static int clear_alarm_int_status(struct device *dev, struct tps80031_rtc *rtc)
{
	int ret;
	u8 buf;

	/**
	 * As per datasheet, A dummy read of this  RTC_STATUS_REG register
	 * is necessary before each I2C read in order to update the status
	 * register value.
	 */
	ret = tps80031_read(dev->parent, TPS80031_SLAVE_ID1,
				TPS80031_RTC_STATUS_REG, &buf);
	if (ret < 0) {
		dev_err(dev, "reading RTC_STATUS failed. err = %d\n", ret);
		return ret;
	}

	/* clear Alarm status bits.*/
	ret = tps80031_set_bits(dev->parent, TPS80031_SLAVE_ID1,
			TPS80031_RTC_STATUS_REG, ALARM_INT_STATUS);
	if (ret < 0) {
		dev_err(dev, "clear Alarm INT failed, err = %d\n", ret);
		return ret;
	}
	return 0;
}

static irqreturn_t tps80031_rtc_irq(int irq, void *data)
{
	struct device *dev = data;
	struct tps80031_rtc *rtc = dev_get_drvdata(dev);
	int ret;

	ret = clear_alarm_int_status(dev, rtc);
	if (ret < 0)
		return ret;

	rtc_update_irq(rtc->rtc, 1, RTC_IRQF | RTC_AF);
	return IRQ_HANDLED;
}

static const struct rtc_class_ops tps80031_rtc_ops = {
	.read_time = tps80031_rtc_read_time,
	.set_time = tps80031_rtc_set_time,
	.set_alarm = tps80031_rtc_set_alarm,
	.read_alarm = tps80031_rtc_read_alarm,
	.alarm_irq_enable = tps80031_rtc_alarm_irq_enable,
};

static int tps80031_rtc_probe(struct platform_device *pdev)
{
	struct tps80031_rtc *rtc;
	struct rtc_time tm;
	int ret;

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

	rtc->irq = platform_get_irq(pdev, 0);
	platform_set_drvdata(pdev, rtc);

	/* Start RTC */
	ret = tps80031_set_bits(pdev->dev.parent, TPS80031_SLAVE_ID1,
			TPS80031_RTC_CTRL_REG, STOP_RTC);
	if (ret < 0) {
		dev_err(&pdev->dev, "failed to start RTC. err = %d\n", ret);
		return ret;
	}

	/* If RTC have POR values, set time 01:01:2000 */
	tps80031_rtc_read_time(&pdev->dev, &tm);
	if ((tm.tm_year == RTC_YEAR_OFFSET + TPS80031_RTC_POR_YEAR) &&
		(tm.tm_mon == (TPS80031_RTC_POR_MONTH - 1)) &&
		(tm.tm_mday == TPS80031_RTC_POR_DAY)) {
		tm.tm_year = 2000;
		tm.tm_mday = 1;
		tm.tm_mon = 1;
		ret = tps80031_rtc_set_time(&pdev->dev, &tm);
		if (ret < 0) {
			dev_err(&pdev->dev,
				"RTC set time failed, err = %d\n", ret);
			return ret;
		}
	}

	/* Clear alarm intretupt status if it is there */
	ret = clear_alarm_int_status(&pdev->dev, rtc);
	if (ret < 0) {
		dev_err(&pdev->dev, "Clear alarm int failed, err = %d\n", ret);
		return ret;
	}

	rtc->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
			       &tps80031_rtc_ops, THIS_MODULE);
	if (IS_ERR(rtc->rtc)) {
		ret = PTR_ERR(rtc->rtc);
		dev_err(&pdev->dev, "RTC registration failed, err %d\n", ret);
		return ret;
	}

	ret = devm_request_threaded_irq(&pdev->dev, rtc->irq, NULL,
			tps80031_rtc_irq,
			IRQF_ONESHOT | IRQF_EARLY_RESUME,
			dev_name(&pdev->dev), rtc);
	if (ret < 0) {
		dev_err(&pdev->dev, "request IRQ:%d failed, err = %d\n",
			 rtc->irq, ret);
		return ret;
	}
	device_set_wakeup_capable(&pdev->dev, 1);
	return 0;
}

static int tps80031_rtc_remove(struct platform_device *pdev)
{
	return 0;
}

#ifdef CONFIG_PM_SLEEP
static int tps80031_rtc_suspend(struct device *dev)
{
	struct tps80031_rtc *rtc = dev_get_drvdata(dev);

	if (device_may_wakeup(dev))
		enable_irq_wake(rtc->irq);
	return 0;
}

static int tps80031_rtc_resume(struct device *dev)
{
	struct tps80031_rtc *rtc = dev_get_drvdata(dev);

	if (device_may_wakeup(dev))
		disable_irq_wake(rtc->irq);
	return 0;
};
#endif

static SIMPLE_DEV_PM_OPS(tps80031_pm_ops, tps80031_rtc_suspend,
			tps80031_rtc_resume);

static struct platform_driver tps80031_rtc_driver = {
	.driver	= {
		.name	= "tps80031-rtc",
		.owner	= THIS_MODULE,
		.pm	= &tps80031_pm_ops,
	},
	.probe	= tps80031_rtc_probe,
	.remove	= tps80031_rtc_remove,
};

module_platform_driver(tps80031_rtc_driver);

MODULE_ALIAS("platform:tps80031-rtc");
MODULE_DESCRIPTION("TI TPS80031/TPS80032 RTC driver");
MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
MODULE_LICENSE("GPL v2");