/*
 * Copyright (c) 2013 Samsung Electronics Co., Ltd
 *	http://www.samsung.com
 *
 *  Copyright (C) 2013 Google, Inc
 *
 *  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; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that 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/i2c.h>
#include <linux/slab.h>
#include <linux/bcd.h>
#include <linux/bitops.h>
#include <linux/regmap.h>
#include <linux/rtc.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/mfd/samsung/core.h>
#include <linux/mfd/samsung/irq.h>
#include <linux/mfd/samsung/rtc.h>

/*
 * Maximum number of retries for checking changes in UDR field
 * of S5M_RTC_UDR_CON register (to limit possible endless loop).
 *
 * After writing to RTC registers (setting time or alarm) read the UDR field
 * in S5M_RTC_UDR_CON register. UDR is auto-cleared when data have
 * been transferred.
 */
#define UDR_READ_RETRY_CNT	5

struct s5m_rtc_info {
	struct device *dev;
	struct i2c_client *i2c;
	struct sec_pmic_dev *s5m87xx;
	struct regmap *regmap;
	struct rtc_device *rtc_dev;
	int irq;
	int device_type;
	int rtc_24hr_mode;
	bool wtsr_smpl;
};

static const struct regmap_config s5m_rtc_regmap_config = {
	.reg_bits = 8,
	.val_bits = 8,

	.max_register = S5M_RTC_REG_MAX,
};

static const struct regmap_config s2mps14_rtc_regmap_config = {
	.reg_bits = 8,
	.val_bits = 8,

	.max_register = S2MPS_RTC_REG_MAX,
};

static void s5m8767_data_to_tm(u8 *data, struct rtc_time *tm,
			       int rtc_24hr_mode)
{
	tm->tm_sec = data[RTC_SEC] & 0x7f;
	tm->tm_min = data[RTC_MIN] & 0x7f;
	if (rtc_24hr_mode) {
		tm->tm_hour = data[RTC_HOUR] & 0x1f;
	} else {
		tm->tm_hour = data[RTC_HOUR] & 0x0f;
		if (data[RTC_HOUR] & HOUR_PM_MASK)
			tm->tm_hour += 12;
	}

	tm->tm_wday = ffs(data[RTC_WEEKDAY] & 0x7f);
	tm->tm_mday = data[RTC_DATE] & 0x1f;
	tm->tm_mon = (data[RTC_MONTH] & 0x0f) - 1;
	tm->tm_year = (data[RTC_YEAR1] & 0x7f) + 100;
	tm->tm_yday = 0;
	tm->tm_isdst = 0;
}

static int s5m8767_tm_to_data(struct rtc_time *tm, u8 *data)
{
	data[RTC_SEC] = tm->tm_sec;
	data[RTC_MIN] = tm->tm_min;

	if (tm->tm_hour >= 12)
		data[RTC_HOUR] = tm->tm_hour | HOUR_PM_MASK;
	else
		data[RTC_HOUR] = tm->tm_hour & ~HOUR_PM_MASK;

	data[RTC_WEEKDAY] = 1 << tm->tm_wday;
	data[RTC_DATE] = tm->tm_mday;
	data[RTC_MONTH] = tm->tm_mon + 1;
	data[RTC_YEAR1] = tm->tm_year > 100 ? (tm->tm_year - 100) : 0;

	if (tm->tm_year < 100) {
		pr_err("s5m8767 RTC cannot handle the year %d.\n",
		       1900 + tm->tm_year);
		return -EINVAL;
	} else {
		return 0;
	}
}

/*
 * Read RTC_UDR_CON register and wait till UDR field is cleared.
 * This indicates that time/alarm update ended.
 */
static inline int s5m8767_wait_for_udr_update(struct s5m_rtc_info *info)
{
	int ret, retry = UDR_READ_RETRY_CNT;
	unsigned int data;

	do {
		ret = regmap_read(info->regmap, S5M_RTC_UDR_CON, &data);
	} while (--retry && (data & S5M_RTC_UDR_MASK) && !ret);

	if (!retry)
		dev_err(info->dev, "waiting for UDR update, reached max number of retries\n");

	return ret;
}

static inline int s5m8767_rtc_set_time_reg(struct s5m_rtc_info *info)
{
	int ret;
	unsigned int data;

	ret = regmap_read(info->regmap, S5M_RTC_UDR_CON, &data);
	if (ret < 0) {
		dev_err(info->dev, "failed to read update reg(%d)\n", ret);
		return ret;
	}

	data |= S5M_RTC_TIME_EN_MASK;
	data |= S5M_RTC_UDR_MASK;

	ret = regmap_write(info->regmap, S5M_RTC_UDR_CON, data);
	if (ret < 0) {
		dev_err(info->dev, "failed to write update reg(%d)\n", ret);
		return ret;
	}

	ret = s5m8767_wait_for_udr_update(info);

	return ret;
}

static inline int s5m8767_rtc_set_alarm_reg(struct s5m_rtc_info *info)
{
	int ret;
	unsigned int data;

	ret = regmap_read(info->regmap, S5M_RTC_UDR_CON, &data);
	if (ret < 0) {
		dev_err(info->dev, "%s: fail to read update reg(%d)\n",
			__func__, ret);
		return ret;
	}

	data &= ~S5M_RTC_TIME_EN_MASK;
	data |= S5M_RTC_UDR_MASK;

	ret = regmap_write(info->regmap, S5M_RTC_UDR_CON, data);
	if (ret < 0) {
		dev_err(info->dev, "%s: fail to write update reg(%d)\n",
			__func__, ret);
		return ret;
	}

	ret = s5m8767_wait_for_udr_update(info);

	return ret;
}

static void s5m8763_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 s5m8763_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 s5m_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
	struct s5m_rtc_info *info = dev_get_drvdata(dev);
	u8 data[8];
	int ret;

	ret = regmap_bulk_read(info->regmap, S5M_RTC_SEC, data, 8);
	if (ret < 0)
		return ret;

	switch (info->device_type) {
	case S5M8763X:
		s5m8763_data_to_tm(data, tm);
		break;

	case S5M8767X:
		s5m8767_data_to_tm(data, tm, info->rtc_24hr_mode);
		break;

	default:
		return -EINVAL;
	}

	dev_dbg(dev, "%s: %d/%d/%d %d:%d:%d(%d)\n", __func__,
		1900 + tm->tm_year, 1 + tm->tm_mon, tm->tm_mday,
		tm->tm_hour, tm->tm_min, tm->tm_sec, tm->tm_wday);

	return rtc_valid_tm(tm);
}

static int s5m_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
	struct s5m_rtc_info *info = dev_get_drvdata(dev);
	u8 data[8];
	int ret = 0;

	switch (info->device_type) {
	case S5M8763X:
		s5m8763_tm_to_data(tm, data);
		break;
	case S5M8767X:
		ret = s5m8767_tm_to_data(tm, data);
		break;
	default:
		return -EINVAL;
	}

	if (ret < 0)
		return ret;

	dev_dbg(dev, "%s: %d/%d/%d %d:%d:%d(%d)\n", __func__,
		1900 + tm->tm_year, 1 + tm->tm_mon, tm->tm_mday,
		tm->tm_hour, tm->tm_min, tm->tm_sec, tm->tm_wday);

	ret = regmap_raw_write(info->regmap, S5M_RTC_SEC, data, 8);
	if (ret < 0)
		return ret;

	ret = s5m8767_rtc_set_time_reg(info);

	return ret;
}

static int s5m_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	struct s5m_rtc_info *info = dev_get_drvdata(dev);
	u8 data[8];
	unsigned int val;
	int ret, i;

	ret = regmap_bulk_read(info->regmap, S5M_ALARM0_SEC, data, 8);
	if (ret < 0)
		return ret;

	switch (info->device_type) {
	case S5M8763X:
		s5m8763_data_to_tm(data, &alrm->time);
		ret = regmap_read(info->regmap, S5M_ALARM0_CONF, &val);
		if (ret < 0)
			return ret;

		alrm->enabled = !!val;

		ret = regmap_read(info->regmap, S5M_RTC_STATUS, &val);
		if (ret < 0)
			return ret;

		break;

	case S5M8767X:
		s5m8767_data_to_tm(data, &alrm->time, info->rtc_24hr_mode);
		dev_dbg(dev, "%s: %d/%d/%d %d:%d:%d(%d)\n", __func__,
			1900 + alrm->time.tm_year, 1 + alrm->time.tm_mon,
			alrm->time.tm_mday, alrm->time.tm_hour,
			alrm->time.tm_min, alrm->time.tm_sec,
			alrm->time.tm_wday);

		alrm->enabled = 0;
		for (i = 0; i < 7; i++) {
			if (data[i] & ALARM_ENABLE_MASK) {
				alrm->enabled = 1;
				break;
			}
		}

		alrm->pending = 0;
		ret = regmap_read(info->regmap, S5M_RTC_STATUS, &val);
		if (ret < 0)
			return ret;
		break;

	default:
		return -EINVAL;
	}

	if (val & S5M_ALARM0_STATUS)
		alrm->pending = 1;
	else
		alrm->pending = 0;

	return 0;
}

static int s5m_rtc_stop_alarm(struct s5m_rtc_info *info)
{
	u8 data[8];
	int ret, i;
	struct rtc_time tm;

	ret = regmap_bulk_read(info->regmap, S5M_ALARM0_SEC, data, 8);
	if (ret < 0)
		return ret;

	s5m8767_data_to_tm(data, &tm, info->rtc_24hr_mode);
	dev_dbg(info->dev, "%s: %d/%d/%d %d:%d:%d(%d)\n", __func__,
		1900 + tm.tm_year, 1 + tm.tm_mon, tm.tm_mday,
		tm.tm_hour, tm.tm_min, tm.tm_sec, tm.tm_wday);

	switch (info->device_type) {
	case S5M8763X:
		ret = regmap_write(info->regmap, S5M_ALARM0_CONF, 0);
		break;

	case S5M8767X:
		for (i = 0; i < 7; i++)
			data[i] &= ~ALARM_ENABLE_MASK;

		ret = regmap_raw_write(info->regmap, S5M_ALARM0_SEC, data, 8);
		if (ret < 0)
			return ret;

		ret = s5m8767_rtc_set_alarm_reg(info);

		break;

	default:
		return -EINVAL;
	}

	return ret;
}

static int s5m_rtc_start_alarm(struct s5m_rtc_info *info)
{
	int ret;
	u8 data[8];
	u8 alarm0_conf;
	struct rtc_time tm;

	ret = regmap_bulk_read(info->regmap, S5M_ALARM0_SEC, data, 8);
	if (ret < 0)
		return ret;

	s5m8767_data_to_tm(data, &tm, info->rtc_24hr_mode);
	dev_dbg(info->dev, "%s: %d/%d/%d %d:%d:%d(%d)\n", __func__,
		1900 + tm.tm_year, 1 + tm.tm_mon, tm.tm_mday,
		tm.tm_hour, tm.tm_min, tm.tm_sec, tm.tm_wday);

	switch (info->device_type) {
	case S5M8763X:
		alarm0_conf = 0x77;
		ret = regmap_write(info->regmap, S5M_ALARM0_CONF, alarm0_conf);
		break;

	case S5M8767X:
		data[RTC_SEC] |= ALARM_ENABLE_MASK;
		data[RTC_MIN] |= ALARM_ENABLE_MASK;
		data[RTC_HOUR] |= ALARM_ENABLE_MASK;
		data[RTC_WEEKDAY] &= ~ALARM_ENABLE_MASK;
		if (data[RTC_DATE] & 0x1f)
			data[RTC_DATE] |= ALARM_ENABLE_MASK;
		if (data[RTC_MONTH] & 0xf)
			data[RTC_MONTH] |= ALARM_ENABLE_MASK;
		if (data[RTC_YEAR1] & 0x7f)
			data[RTC_YEAR1] |= ALARM_ENABLE_MASK;

		ret = regmap_raw_write(info->regmap, S5M_ALARM0_SEC, data, 8);
		if (ret < 0)
			return ret;
		ret = s5m8767_rtc_set_alarm_reg(info);

		break;

	default:
		return -EINVAL;
	}

	return ret;
}

static int s5m_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	struct s5m_rtc_info *info = dev_get_drvdata(dev);
	u8 data[8];
	int ret;

	switch (info->device_type) {
	case S5M8763X:
		s5m8763_tm_to_data(&alrm->time, data);
		break;

	case S5M8767X:
		s5m8767_tm_to_data(&alrm->time, data);
		break;

	default:
		return -EINVAL;
	}

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

	ret = s5m_rtc_stop_alarm(info);
	if (ret < 0)
		return ret;

	ret = regmap_raw_write(info->regmap, S5M_ALARM0_SEC, data, 8);
	if (ret < 0)
		return ret;

	ret = s5m8767_rtc_set_alarm_reg(info);
	if (ret < 0)
		return ret;

	if (alrm->enabled)
		ret = s5m_rtc_start_alarm(info);

	return ret;
}

static int s5m_rtc_alarm_irq_enable(struct device *dev,
				    unsigned int enabled)
{
	struct s5m_rtc_info *info = dev_get_drvdata(dev);

	if (enabled)
		return s5m_rtc_start_alarm(info);
	else
		return s5m_rtc_stop_alarm(info);
}

static irqreturn_t s5m_rtc_alarm_irq(int irq, void *data)
{
	struct s5m_rtc_info *info = data;

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

	return IRQ_HANDLED;
}

static const struct rtc_class_ops s5m_rtc_ops = {
	.read_time = s5m_rtc_read_time,
	.set_time = s5m_rtc_set_time,
	.read_alarm = s5m_rtc_read_alarm,
	.set_alarm = s5m_rtc_set_alarm,
	.alarm_irq_enable = s5m_rtc_alarm_irq_enable,
};

static void s5m_rtc_enable_wtsr(struct s5m_rtc_info *info, bool enable)
{
	int ret;
	ret = regmap_update_bits(info->regmap, S5M_WTSR_SMPL_CNTL,
				 WTSR_ENABLE_MASK,
				 enable ? WTSR_ENABLE_MASK : 0);
	if (ret < 0)
		dev_err(info->dev, "%s: fail to update WTSR reg(%d)\n",
			__func__, ret);
}

static void s5m_rtc_enable_smpl(struct s5m_rtc_info *info, bool enable)
{
	int ret;
	ret = regmap_update_bits(info->regmap, S5M_WTSR_SMPL_CNTL,
				 SMPL_ENABLE_MASK,
				 enable ? SMPL_ENABLE_MASK : 0);
	if (ret < 0)
		dev_err(info->dev, "%s: fail to update SMPL reg(%d)\n",
			__func__, ret);
}

static int s5m8767_rtc_init_reg(struct s5m_rtc_info *info)
{
	u8 data[2];
	int ret;

	/* Set RTC control register : Binary mode, 24hour mode */
	data[0] = (1 << BCD_EN_SHIFT) | (1 << MODEL24_SHIFT);
	data[1] = (0 << BCD_EN_SHIFT) | (1 << MODEL24_SHIFT);

	info->rtc_24hr_mode = 1;
	ret = regmap_raw_write(info->regmap, S5M_ALARM0_CONF, data, 2);
	if (ret < 0) {
		dev_err(info->dev, "%s: fail to write controlm reg(%d)\n",
			__func__, ret);
		return ret;
	}

	return ret;
}

static int s5m_rtc_probe(struct platform_device *pdev)
{
	struct sec_pmic_dev *s5m87xx = dev_get_drvdata(pdev->dev.parent);
	struct sec_platform_data *pdata = s5m87xx->pdata;
	struct s5m_rtc_info *info;
	const struct regmap_config *regmap_cfg;
	int ret;

	if (!pdata) {
		dev_err(pdev->dev.parent, "Platform data not supplied\n");
		return -ENODEV;
	}

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

	switch (pdata->device_type) {
	case S2MPS14X:
		regmap_cfg = &s2mps14_rtc_regmap_config;
		break;
	case S5M8763X:
		regmap_cfg = &s5m_rtc_regmap_config;
		break;
	case S5M8767X:
		regmap_cfg = &s5m_rtc_regmap_config;
		break;
	default:
		dev_err(&pdev->dev, "Device type is not supported by RTC driver\n");
		return -ENODEV;
	}

	info->i2c = i2c_new_dummy(s5m87xx->i2c->adapter, RTC_I2C_ADDR);
	if (!info->i2c) {
		dev_err(&pdev->dev, "Failed to allocate I2C for RTC\n");
		return -ENODEV;
	}

	info->regmap = devm_regmap_init_i2c(info->i2c, regmap_cfg);
	if (IS_ERR(info->regmap)) {
		ret = PTR_ERR(info->regmap);
		dev_err(&pdev->dev, "Failed to allocate RTC register map: %d\n",
				ret);
		goto err;
	}

	info->dev = &pdev->dev;
	info->s5m87xx = s5m87xx;
	info->device_type = s5m87xx->device_type;
	info->wtsr_smpl = s5m87xx->wtsr_smpl;

	switch (pdata->device_type) {
	case S5M8763X:
		info->irq = regmap_irq_get_virq(s5m87xx->irq_data,
				S5M8763_IRQ_ALARM0);
		break;

	case S5M8767X:
		info->irq = regmap_irq_get_virq(s5m87xx->irq_data,
				S5M8767_IRQ_RTCA1);
		break;

	default:
		ret = -EINVAL;
		dev_err(&pdev->dev, "Unsupported device type: %d\n", ret);
		goto err;
	}

	platform_set_drvdata(pdev, info);

	ret = s5m8767_rtc_init_reg(info);

	if (info->wtsr_smpl) {
		s5m_rtc_enable_wtsr(info, true);
		s5m_rtc_enable_smpl(info, true);
	}

	device_init_wakeup(&pdev->dev, 1);

	info->rtc_dev = devm_rtc_device_register(&pdev->dev, "s5m-rtc",
						 &s5m_rtc_ops, THIS_MODULE);

	if (IS_ERR(info->rtc_dev)) {
		ret = PTR_ERR(info->rtc_dev);
		goto err;
	}

	ret = devm_request_threaded_irq(&pdev->dev, info->irq, NULL,
					s5m_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);
		goto err;
	}

	return 0;

err:
	i2c_unregister_device(info->i2c);

	return ret;
}

static void s5m_rtc_shutdown(struct platform_device *pdev)
{
	struct s5m_rtc_info *info = platform_get_drvdata(pdev);
	int i;
	unsigned int val = 0;
	if (info->wtsr_smpl) {
		for (i = 0; i < 3; i++) {
			s5m_rtc_enable_wtsr(info, false);
			regmap_read(info->regmap, S5M_WTSR_SMPL_CNTL, &val);
			pr_debug("%s: WTSR_SMPL reg(0x%02x)\n", __func__, val);
			if (val & WTSR_ENABLE_MASK)
				pr_emerg("%s: fail to disable WTSR\n",
					 __func__);
			else {
				pr_info("%s: success to disable WTSR\n",
					__func__);
				break;
			}
		}
	}
	/* Disable SMPL when power off */
	s5m_rtc_enable_smpl(info, false);
}

static int s5m_rtc_remove(struct platform_device *pdev)
{
	struct s5m_rtc_info *info = platform_get_drvdata(pdev);

	/* Perform also all shutdown steps when removing */
	s5m_rtc_shutdown(pdev);
	i2c_unregister_device(info->i2c);

	return 0;
}

#ifdef CONFIG_PM_SLEEP
static int s5m_rtc_resume(struct device *dev)
{
	struct s5m_rtc_info *info = dev_get_drvdata(dev);
	int ret = 0;

	if (device_may_wakeup(dev))
		ret = disable_irq_wake(info->irq);

	return ret;
}

static int s5m_rtc_suspend(struct device *dev)
{
	struct s5m_rtc_info *info = dev_get_drvdata(dev);
	int ret = 0;

	if (device_may_wakeup(dev))
		ret = enable_irq_wake(info->irq);

	return ret;
}
#endif /* CONFIG_PM_SLEEP */

static SIMPLE_DEV_PM_OPS(s5m_rtc_pm_ops, s5m_rtc_suspend, s5m_rtc_resume);

static const struct platform_device_id s5m_rtc_id[] = {
	{ "s5m-rtc", 0 },
};

static struct platform_driver s5m_rtc_driver = {
	.driver		= {
		.name	= "s5m-rtc",
		.owner	= THIS_MODULE,
		.pm	= &s5m_rtc_pm_ops,
	},
	.probe		= s5m_rtc_probe,
	.remove		= s5m_rtc_remove,
	.shutdown	= s5m_rtc_shutdown,
	.id_table	= s5m_rtc_id,
};

module_platform_driver(s5m_rtc_driver);

/* Module information */
MODULE_AUTHOR("Sangbeom Kim <sbkim73@samsung.com>");
MODULE_DESCRIPTION("Samsung S5M RTC driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:s5m-rtc");