/*
   * RTC driver for Maxim MAX77686
   *
   * Copyright (C) 2012 Samsung Electronics Co.Ltd
   *
   *  based on rtc-max8997.c
   *
   *  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.
   *
   */
  
  #include <linux/slab.h>
  #include <linux/rtc.h>
  #include <linux/delay.h>
  #include <linux/mutex.h>
  #include <linux/module.h>
  #include <linux/platform_device.h>
  #include <linux/mfd/max77686-private.h>
  #include <linux/irqdomain.h>
  #include <linux/regmap.h>
  
  /* RTC Control Register */
  #define BCD_EN_SHIFT			0

  #define BCD_EN_MASK			(1 << BCD_EN_SHIFT)

  #define MODEL24_SHIFT			1
  #define MODEL24_MASK			(1 << MODEL24_SHIFT)
  /* RTC Update Register1 */
  #define RTC_UDR_SHIFT			0
  #define RTC_UDR_MASK			(1 << RTC_UDR_SHIFT)
  #define RTC_RBUDR_SHIFT			4
  #define RTC_RBUDR_MASK			(1 << RTC_RBUDR_SHIFT)

  /* RTC Hour register */
  #define HOUR_PM_SHIFT			6
  #define HOUR_PM_MASK			(1 << HOUR_PM_SHIFT)
  /* RTC Alarm Enable */
  #define ALARM_ENABLE_SHIFT		7
  #define ALARM_ENABLE_MASK		(1 << ALARM_ENABLE_SHIFT)
  
  #define MAX77686_RTC_UPDATE_DELAY	16

  
  enum {
  	RTC_SEC = 0,
  	RTC_MIN,
  	RTC_HOUR,
  	RTC_WEEKDAY,
  	RTC_MONTH,
  	RTC_YEAR,
  	RTC_DATE,
  	RTC_NR_TIME
  };
  
  struct max77686_rtc_info {
  	struct device		*dev;
  	struct max77686_dev	*max77686;
  	struct i2c_client	*rtc;
  	struct rtc_device	*rtc_dev;
  	struct mutex		lock;
  
  	struct regmap		*regmap;
  
  	int virq;
  	int rtc_24hr_mode;
  };
  
  enum MAX77686_RTC_OP {
  	MAX77686_RTC_WRITE,
  	MAX77686_RTC_READ,
  };

  static void max77686_rtc_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;
  	}

  	/* Only a single bit is set in data[], so fls() would be equivalent */
  	tm->tm_wday = ffs(data[RTC_WEEKDAY] & 0x7f) - 1;

  	tm->tm_mday = data[RTC_DATE] & 0x1f;
  	tm->tm_mon = (data[RTC_MONTH] & 0x0f) - 1;
  	tm->tm_year = (data[RTC_YEAR] & 0x7f) + 100;
  	tm->tm_yday = 0;
  	tm->tm_isdst = 0;
  }
  
  static int max77686_rtc_tm_to_data(struct rtc_time *tm, u8 *data)
  {
  	data[RTC_SEC] = tm->tm_sec;
  	data[RTC_MIN] = tm->tm_min;
  	data[RTC_HOUR] = tm->tm_hour;
  	data[RTC_WEEKDAY] = 1 << tm->tm_wday;
  	data[RTC_DATE] = tm->tm_mday;
  	data[RTC_MONTH] = tm->tm_mon + 1;

  	data[RTC_YEAR] = tm->tm_year > 100 ? (tm->tm_year - 100) : 0;

  
  	if (tm->tm_year < 100) {
  		pr_warn("%s: MAX77686 RTC cannot handle the year %d."
  			"Assume it's 2000.
  ", __func__, 1900 + tm->tm_year);
  		return -EINVAL;
  	}
  	return 0;
  }
  
  static int max77686_rtc_update(struct max77686_rtc_info *info,
  	enum MAX77686_RTC_OP op)
  {
  	int ret;
  	unsigned int data;
  
  	if (op == MAX77686_RTC_WRITE)
  		data = 1 << RTC_UDR_SHIFT;
  	else
  		data = 1 << RTC_RBUDR_SHIFT;
  
  	ret = regmap_update_bits(info->max77686->rtc_regmap,
  				 MAX77686_RTC_UPDATE0, data, data);
  	if (ret < 0)
  		dev_err(info->dev, "%s: fail to write update reg(ret=%d, data=0x%x)
  ",
  				__func__, ret, data);
  	else {
  		/* Minimum 16ms delay required before RTC update. */
  		msleep(MAX77686_RTC_UPDATE_DELAY);
  	}
  
  	return ret;
  }
  
  static int max77686_rtc_read_time(struct device *dev, struct rtc_time *tm)
  {
  	struct max77686_rtc_info *info = dev_get_drvdata(dev);
  	u8 data[RTC_NR_TIME];
  	int ret;
  
  	mutex_lock(&info->lock);
  
  	ret = max77686_rtc_update(info, MAX77686_RTC_READ);
  	if (ret < 0)
  		goto out;
  
  	ret = regmap_bulk_read(info->max77686->rtc_regmap,
  				MAX77686_RTC_SEC, data, RTC_NR_TIME);
  	if (ret < 0) {
  		dev_err(info->dev, "%s: fail to read time reg(%d)
  ", __func__,	ret);
  		goto out;
  	}
  
  	max77686_rtc_data_to_tm(data, tm, info->rtc_24hr_mode);
  
  	ret = rtc_valid_tm(tm);
  
  out:
  	mutex_unlock(&info->lock);
  	return ret;
  }
  
  static int max77686_rtc_set_time(struct device *dev, struct rtc_time *tm)
  {
  	struct max77686_rtc_info *info = dev_get_drvdata(dev);
  	u8 data[RTC_NR_TIME];
  	int ret;
  
  	ret = max77686_rtc_tm_to_data(tm, data);
  	if (ret < 0)
  		return ret;
  
  	mutex_lock(&info->lock);
  
  	ret = regmap_bulk_write(info->max77686->rtc_regmap,
  				 MAX77686_RTC_SEC, data, RTC_NR_TIME);
  	if (ret < 0) {
  		dev_err(info->dev, "%s: fail to write time reg(%d)
  ", __func__,
  				ret);
  		goto out;
  	}
  
  	ret = max77686_rtc_update(info, MAX77686_RTC_WRITE);
  
  out:
  	mutex_unlock(&info->lock);
  	return ret;
  }
  
  static int max77686_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
  {
  	struct max77686_rtc_info *info = dev_get_drvdata(dev);
  	u8 data[RTC_NR_TIME];
  	unsigned int val;
  	int i, ret;
  
  	mutex_lock(&info->lock);
  
  	ret = max77686_rtc_update(info, MAX77686_RTC_READ);
  	if (ret < 0)
  		goto out;
  
  	ret = regmap_bulk_read(info->max77686->rtc_regmap,
  				 MAX77686_ALARM1_SEC, data, RTC_NR_TIME);
  	if (ret < 0) {
  		dev_err(info->dev, "%s:%d fail to read alarm reg(%d)
  ",
  				__func__, __LINE__, ret);
  		goto out;
  	}
  
  	max77686_rtc_data_to_tm(data, &alrm->time, info->rtc_24hr_mode);
  
  	alrm->enabled = 0;
  	for (i = 0; i < RTC_NR_TIME; i++) {
  		if (data[i] & ALARM_ENABLE_MASK) {
  			alrm->enabled = 1;
  			break;
  		}
  	}
  
  	alrm->pending = 0;

  	ret = regmap_read(info->max77686->regmap, MAX77686_REG_STATUS2, &val);

  	if (ret < 0) {

  		dev_err(info->dev, "%s:%d fail to read status2 reg(%d)
  ",

  				__func__, __LINE__, ret);
  		goto out;
  	}
  
  	if (val & (1 << 4)) /* RTCA1 */
  		alrm->pending = 1;
  
  out:
  	mutex_unlock(&info->lock);
  	return 0;
  }
  
  static int max77686_rtc_stop_alarm(struct max77686_rtc_info *info)
  {
  	u8 data[RTC_NR_TIME];
  	int ret, i;
  	struct rtc_time tm;
  
  	if (!mutex_is_locked(&info->lock))
  		dev_warn(info->dev, "%s: should have mutex locked
  ", __func__);
  
  	ret = max77686_rtc_update(info, MAX77686_RTC_READ);
  	if (ret < 0)
  		goto out;
  
  	ret = regmap_bulk_read(info->max77686->rtc_regmap,
  				 MAX77686_ALARM1_SEC, data, RTC_NR_TIME);
  	if (ret < 0) {
  		dev_err(info->dev, "%s: fail to read alarm reg(%d)
  ",
  				__func__, ret);
  		goto out;
  	}
  
  	max77686_rtc_data_to_tm(data, &tm, info->rtc_24hr_mode);
  
  	for (i = 0; i < RTC_NR_TIME; i++)
  		data[i] &= ~ALARM_ENABLE_MASK;
  
  	ret = regmap_bulk_write(info->max77686->rtc_regmap,
  				 MAX77686_ALARM1_SEC, data, RTC_NR_TIME);
  	if (ret < 0) {
  		dev_err(info->dev, "%s: fail to write alarm reg(%d)
  ",
  				__func__, ret);
  		goto out;
  	}
  
  	ret = max77686_rtc_update(info, MAX77686_RTC_WRITE);
  out:
  	return ret;
  }
  
  static int max77686_rtc_start_alarm(struct max77686_rtc_info *info)
  {
  	u8 data[RTC_NR_TIME];
  	int ret;
  	struct rtc_time tm;
  
  	if (!mutex_is_locked(&info->lock))
  		dev_warn(info->dev, "%s: should have mutex locked
  ", __func__);
  
  	ret = max77686_rtc_update(info, MAX77686_RTC_READ);
  	if (ret < 0)
  		goto out;
  
  	ret = regmap_bulk_read(info->max77686->rtc_regmap,
  				 MAX77686_ALARM1_SEC, data, RTC_NR_TIME);
  	if (ret < 0) {
  		dev_err(info->dev, "%s: fail to read alarm reg(%d)
  ",
  				__func__, ret);
  		goto out;
  	}
  
  	max77686_rtc_data_to_tm(data, &tm, info->rtc_24hr_mode);
  
  	data[RTC_SEC] |= (1 << ALARM_ENABLE_SHIFT);
  	data[RTC_MIN] |= (1 << ALARM_ENABLE_SHIFT);
  	data[RTC_HOUR] |= (1 << ALARM_ENABLE_SHIFT);
  	data[RTC_WEEKDAY] &= ~ALARM_ENABLE_MASK;
  	if (data[RTC_MONTH] & 0xf)
  		data[RTC_MONTH] |= (1 << ALARM_ENABLE_SHIFT);
  	if (data[RTC_YEAR] & 0x7f)
  		data[RTC_YEAR] |= (1 << ALARM_ENABLE_SHIFT);
  	if (data[RTC_DATE] & 0x1f)
  		data[RTC_DATE] |= (1 << ALARM_ENABLE_SHIFT);
  
  	ret = regmap_bulk_write(info->max77686->rtc_regmap,
  				 MAX77686_ALARM1_SEC, data, RTC_NR_TIME);
  	if (ret < 0) {
  		dev_err(info->dev, "%s: fail to write alarm reg(%d)
  ",
  				__func__, ret);
  		goto out;
  	}
  
  	ret = max77686_rtc_update(info, MAX77686_RTC_WRITE);
  out:
  	return ret;
  }
  
  static int max77686_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
  {
  	struct max77686_rtc_info *info = dev_get_drvdata(dev);
  	u8 data[RTC_NR_TIME];
  	int ret;
  
  	ret = max77686_rtc_tm_to_data(&alrm->time, data);
  	if (ret < 0)
  		return ret;
  
  	mutex_lock(&info->lock);
  
  	ret = max77686_rtc_stop_alarm(info);
  	if (ret < 0)
  		goto out;
  
  	ret = regmap_bulk_write(info->max77686->rtc_regmap,
  				 MAX77686_ALARM1_SEC, data, RTC_NR_TIME);
  
  	if (ret < 0) {
  		dev_err(info->dev, "%s: fail to write alarm reg(%d)
  ",
  				__func__, ret);
  		goto out;
  	}
  
  	ret = max77686_rtc_update(info, MAX77686_RTC_WRITE);
  	if (ret < 0)
  		goto out;
  
  	if (alrm->enabled)
  		ret = max77686_rtc_start_alarm(info);
  out:
  	mutex_unlock(&info->lock);
  	return ret;
  }
  
  static int max77686_rtc_alarm_irq_enable(struct device *dev,
  					unsigned int enabled)
  {
  	struct max77686_rtc_info *info = dev_get_drvdata(dev);
  	int ret;
  
  	mutex_lock(&info->lock);
  	if (enabled)
  		ret = max77686_rtc_start_alarm(info);
  	else
  		ret = max77686_rtc_stop_alarm(info);
  	mutex_unlock(&info->lock);
  
  	return ret;
  }
  
  static irqreturn_t max77686_rtc_alarm_irq(int irq, void *data)
  {
  	struct max77686_rtc_info *info = data;
  
  	dev_info(info->dev, "%s:irq(%d)
  ", __func__, irq);
  
  	rtc_update_irq(info->rtc_dev, 1, RTC_IRQF | RTC_AF);
  
  	return IRQ_HANDLED;
  }
  
  static const struct rtc_class_ops max77686_rtc_ops = {
  	.read_time = max77686_rtc_read_time,
  	.set_time = max77686_rtc_set_time,
  	.read_alarm = max77686_rtc_read_alarm,
  	.set_alarm = max77686_rtc_set_alarm,
  	.alarm_irq_enable = max77686_rtc_alarm_irq_enable,
  };

  static int max77686_rtc_init_reg(struct max77686_rtc_info *info)
  {
  	u8 data[2];
  	int ret;
  
  	/* Set RTC control register : Binary mode, 24hour mdoe */
  	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_bulk_write(info->max77686->rtc_regmap, MAX77686_RTC_CONTROLM, data, 2);
  	if (ret < 0) {
  		dev_err(info->dev, "%s: fail to write controlm reg(%d)
  ",
  				__func__, ret);
  		return ret;
  	}
  
  	ret = max77686_rtc_update(info, MAX77686_RTC_WRITE);
  	return ret;
  }

  static int max77686_rtc_probe(struct platform_device *pdev)
  {
  	struct max77686_dev *max77686 = dev_get_drvdata(pdev->dev.parent);
  	struct max77686_rtc_info *info;

  	int ret;

  	dev_info(&pdev->dev, "%s
  ", __func__);

  	info = devm_kzalloc(&pdev->dev, sizeof(struct max77686_rtc_info),
  				GFP_KERNEL);

  	if (!info)
  		return -ENOMEM;
  
  	mutex_init(&info->lock);
  	info->dev = &pdev->dev;
  	info->max77686 = max77686;
  	info->rtc = max77686->rtc;

  	platform_set_drvdata(pdev, info);
  
  	ret = max77686_rtc_init_reg(info);
  
  	if (ret < 0) {
  		dev_err(&pdev->dev, "Failed to initialize RTC reg:%d
  ", ret);
  		goto err_rtc;
  	}

  	device_init_wakeup(&pdev->dev, 1);

  	info->rtc_dev = devm_rtc_device_register(&pdev->dev, "max77686-rtc",
  					&max77686_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
  ", ret);
  		if (ret == 0)
  			ret = -EINVAL;
  		goto err_rtc;
  	}

  	if (!max77686->rtc_irq_data) {
  		ret = -EINVAL;
  		dev_err(&pdev->dev, "%s: no RTC regmap IRQ chip
  ", __func__);
  		goto err_rtc;
  	}

  	info->virq = regmap_irq_get_virq(max77686->rtc_irq_data,
  					 MAX77686_RTCIRQ_RTCA1);
  	if (!info->virq) {

  		ret = -ENXIO;

  		goto err_rtc;

  	}

  	ret = devm_request_threaded_irq(&pdev->dev, info->virq, NULL,
  				max77686_rtc_alarm_irq, 0, "rtc-alarm1", info);

  	if (ret < 0)

  		dev_err(&pdev->dev, "Failed to request alarm IRQ: %d: %d
  ",
  			info->virq, ret);

  err_rtc:

  	return ret;
  }

  #ifdef CONFIG_PM_SLEEP
  static int max77686_rtc_suspend(struct device *dev)
  {
  	if (device_may_wakeup(dev)) {
  		struct max77686_rtc_info *info = dev_get_drvdata(dev);
  
  		return enable_irq_wake(info->virq);
  	}
  
  	return 0;
  }
  
  static int max77686_rtc_resume(struct device *dev)
  {
  	if (device_may_wakeup(dev)) {
  		struct max77686_rtc_info *info = dev_get_drvdata(dev);
  
  		return disable_irq_wake(info->virq);
  	}
  
  	return 0;
  }
  #endif
  
  static SIMPLE_DEV_PM_OPS(max77686_rtc_pm_ops,
  			 max77686_rtc_suspend, max77686_rtc_resume);

  static const struct platform_device_id rtc_id[] = {
  	{ "max77686-rtc", 0 },
  	{},
  };
  
  static struct platform_driver max77686_rtc_driver = {
  	.driver		= {
  		.name	= "max77686-rtc",
  		.owner	= THIS_MODULE,

  		.pm	= &max77686_rtc_pm_ops,

  	},
  	.probe		= max77686_rtc_probe,

  	.id_table	= rtc_id,
  };

  module_platform_driver(max77686_rtc_driver);

  
  MODULE_DESCRIPTION("Maxim MAX77686 RTC driver");

  MODULE_AUTHOR("Chiwoong Byun <woong.byun@samsung.com>");

  MODULE_LICENSE("GPL");